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Comparing jsr166/src/jsr166e/ConcurrentHashMapV8.java (file contents):
Revision 1.48 by jsr166, Fri Jul 6 21:39:18 2012 UTC vs.
Revision 1.115 by jsr166, Fri Aug 23 20:12:21 2013 UTC

# Line 5 | Line 5
5   */
6  
7   package jsr166e;
8 < import jsr166e.LongAdder;
8 >
9 > import jsr166e.ForkJoinPool;
10 >
11 > import java.io.ObjectStreamField;
12 > import java.io.Serializable;
13 > import java.lang.reflect.ParameterizedType;
14 > import java.lang.reflect.Type;
15 > import java.util.AbstractMap;
16   import java.util.Arrays;
10 import java.util.Map;
11 import java.util.Set;
17   import java.util.Collection;
18 < import java.util.AbstractMap;
19 < import java.util.AbstractSet;
20 < import java.util.AbstractCollection;
16 < import java.util.Hashtable;
18 > import java.util.Comparator;
19 > import java.util.ConcurrentModificationException;
20 > import java.util.Enumeration;
21   import java.util.HashMap;
22 + import java.util.Hashtable;
23   import java.util.Iterator;
24 < import java.util.Enumeration;
20 < import java.util.ConcurrentModificationException;
24 > import java.util.Map;
25   import java.util.NoSuchElementException;
26 + import java.util.Set;
27   import java.util.concurrent.ConcurrentMap;
28 < import java.util.concurrent.ThreadLocalRandom;
28 > import java.util.concurrent.atomic.AtomicReference;
29 > import java.util.concurrent.atomic.AtomicInteger;
30   import java.util.concurrent.locks.LockSupport;
31 < import java.util.concurrent.locks.AbstractQueuedSynchronizer;
26 < import java.io.Serializable;
31 > import java.util.concurrent.locks.ReentrantLock;
32  
33   /**
34   * A hash table supporting full concurrency of retrievals and
# Line 37 | Line 42 | import java.io.Serializable;
42   * interoperable with {@code Hashtable} in programs that rely on its
43   * thread safety but not on its synchronization details.
44   *
45 < * <p> Retrieval operations (including {@code get}) generally do not
45 > * <p>Retrieval operations (including {@code get}) generally do not
46   * block, so may overlap with update operations (including {@code put}
47   * and {@code remove}). Retrievals reflect the results of the most
48   * recently <em>completed</em> update operations holding upon their
49 < * onset.  For aggregate operations such as {@code putAll} and {@code
50 < * clear}, concurrent retrievals may reflect insertion or removal of
51 < * only some entries.  Similarly, Iterators and Enumerations return
52 < * elements reflecting the state of the hash table at some point at or
53 < * since the creation of the iterator/enumeration.  They do
54 < * <em>not</em> throw {@link ConcurrentModificationException}.
55 < * However, iterators are designed to be used by only one thread at a
56 < * time.  Bear in mind that the results of aggregate status methods
57 < * including {@code size}, {@code isEmpty}, and {@code containsValue}
58 < * are typically useful only when a map is not undergoing concurrent
59 < * updates in other threads.  Otherwise the results of these methods
60 < * reflect transient states that may be adequate for monitoring
61 < * or estimation purposes, but not for program control.
49 > * onset. (More formally, an update operation for a given key bears a
50 > * <em>happens-before</em> relation with any (non-null) retrieval for
51 > * that key reporting the updated value.)  For aggregate operations
52 > * such as {@code putAll} and {@code clear}, concurrent retrievals may
53 > * reflect insertion or removal of only some entries.  Similarly,
54 > * Iterators and Enumerations return elements reflecting the state of
55 > * the hash table at some point at or since the creation of the
56 > * iterator/enumeration.  They do <em>not</em> throw {@link
57 > * ConcurrentModificationException}.  However, iterators are designed
58 > * to be used by only one thread at a time.  Bear in mind that the
59 > * results of aggregate status methods including {@code size}, {@code
60 > * isEmpty}, and {@code containsValue} are typically useful only when
61 > * a map is not undergoing concurrent updates in other threads.
62 > * Otherwise the results of these methods reflect transient states
63 > * that may be adequate for monitoring or estimation purposes, but not
64 > * for program control.
65   *
66 < * <p> The table is dynamically expanded when there are too many
66 > * <p>The table is dynamically expanded when there are too many
67   * collisions (i.e., keys that have distinct hash codes but fall into
68   * the same slot modulo the table size), with the expected average
69   * effect of maintaining roughly two bins per mapping (corresponding
# Line 74 | Line 82 | import java.io.Serializable;
82   * expected {@code concurrencyLevel} as an additional hint for
83   * internal sizing.  Note that using many keys with exactly the same
84   * {@code hashCode()} is a sure way to slow down performance of any
85 < * hash table.
85 > * hash table. To ameliorate impact, when keys are {@link Comparable},
86 > * this class may use comparison order among keys to help break ties.
87 > *
88 > * <p>A {@link Set} projection of a ConcurrentHashMapV8 may be created
89 > * (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed
90 > * (using {@link #keySet(Object)} when only keys are of interest, and the
91 > * mapped values are (perhaps transiently) not used or all take the
92 > * same mapping value.
93   *
94   * <p>This class and its views and iterators implement all of the
95   * <em>optional</em> methods of the {@link Map} and {@link Iterator}
96   * interfaces.
97   *
98 < * <p> Like {@link Hashtable} but unlike {@link HashMap}, this class
98 > * <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
99   * does <em>not</em> allow {@code null} to be used as a key or value.
100   *
101 + * <p>ConcurrentHashMapV8s support a set of sequential and parallel bulk
102 + * operations that are designed
103 + * to be safely, and often sensibly, applied even with maps that are
104 + * being concurrently updated by other threads; for example, when
105 + * computing a snapshot summary of the values in a shared registry.
106 + * There are three kinds of operation, each with four forms, accepting
107 + * functions with Keys, Values, Entries, and (Key, Value) arguments
108 + * and/or return values. Because the elements of a ConcurrentHashMapV8
109 + * are not ordered in any particular way, and may be processed in
110 + * different orders in different parallel executions, the correctness
111 + * of supplied functions should not depend on any ordering, or on any
112 + * other objects or values that may transiently change while
113 + * computation is in progress; and except for forEach actions, should
114 + * ideally be side-effect-free. Bulk operations on {@link java.util.Map.Entry}
115 + * objects do not support method {@code setValue}.
116 + *
117 + * <ul>
118 + * <li> forEach: Perform a given action on each element.
119 + * A variant form applies a given transformation on each element
120 + * before performing the action.</li>
121 + *
122 + * <li> search: Return the first available non-null result of
123 + * applying a given function on each element; skipping further
124 + * search when a result is found.</li>
125 + *
126 + * <li> reduce: Accumulate each element.  The supplied reduction
127 + * function cannot rely on ordering (more formally, it should be
128 + * both associative and commutative).  There are five variants:
129 + *
130 + * <ul>
131 + *
132 + * <li> Plain reductions. (There is not a form of this method for
133 + * (key, value) function arguments since there is no corresponding
134 + * return type.)</li>
135 + *
136 + * <li> Mapped reductions that accumulate the results of a given
137 + * function applied to each element.</li>
138 + *
139 + * <li> Reductions to scalar doubles, longs, and ints, using a
140 + * given basis value.</li>
141 + *
142 + * </ul>
143 + * </li>
144 + * </ul>
145 + *
146 + * <p>These bulk operations accept a {@code parallelismThreshold}
147 + * argument. Methods proceed sequentially if the current map size is
148 + * estimated to be less than the given threshold. Using a value of
149 + * {@code Long.MAX_VALUE} suppresses all parallelism.  Using a value
150 + * of {@code 1} results in maximal parallelism by partitioning into
151 + * enough subtasks to fully utilize the {@link
152 + * ForkJoinPool#commonPool()} that is used for all parallel
153 + * computations. Normally, you would initially choose one of these
154 + * extreme values, and then measure performance of using in-between
155 + * values that trade off overhead versus throughput.
156 + *
157 + * <p>The concurrency properties of bulk operations follow
158 + * from those of ConcurrentHashMapV8: Any non-null result returned
159 + * from {@code get(key)} and related access methods bears a
160 + * happens-before relation with the associated insertion or
161 + * update.  The result of any bulk operation reflects the
162 + * composition of these per-element relations (but is not
163 + * necessarily atomic with respect to the map as a whole unless it
164 + * is somehow known to be quiescent).  Conversely, because keys
165 + * and values in the map are never null, null serves as a reliable
166 + * atomic indicator of the current lack of any result.  To
167 + * maintain this property, null serves as an implicit basis for
168 + * all non-scalar reduction operations. For the double, long, and
169 + * int versions, the basis should be one that, when combined with
170 + * any other value, returns that other value (more formally, it
171 + * should be the identity element for the reduction). Most common
172 + * reductions have these properties; for example, computing a sum
173 + * with basis 0 or a minimum with basis MAX_VALUE.
174 + *
175 + * <p>Search and transformation functions provided as arguments
176 + * should similarly return null to indicate the lack of any result
177 + * (in which case it is not used). In the case of mapped
178 + * reductions, this also enables transformations to serve as
179 + * filters, returning null (or, in the case of primitive
180 + * specializations, the identity basis) if the element should not
181 + * be combined. You can create compound transformations and
182 + * filterings by composing them yourself under this "null means
183 + * there is nothing there now" rule before using them in search or
184 + * reduce operations.
185 + *
186 + * <p>Methods accepting and/or returning Entry arguments maintain
187 + * key-value associations. They may be useful for example when
188 + * finding the key for the greatest value. Note that "plain" Entry
189 + * arguments can be supplied using {@code new
190 + * AbstractMap.SimpleEntry(k,v)}.
191 + *
192 + * <p>Bulk operations may complete abruptly, throwing an
193 + * exception encountered in the application of a supplied
194 + * function. Bear in mind when handling such exceptions that other
195 + * concurrently executing functions could also have thrown
196 + * exceptions, or would have done so if the first exception had
197 + * not occurred.
198 + *
199 + * <p>Speedups for parallel compared to sequential forms are common
200 + * but not guaranteed.  Parallel operations involving brief functions
201 + * on small maps may execute more slowly than sequential forms if the
202 + * underlying work to parallelize the computation is more expensive
203 + * than the computation itself.  Similarly, parallelization may not
204 + * lead to much actual parallelism if all processors are busy
205 + * performing unrelated tasks.
206 + *
207 + * <p>All arguments to all task methods must be non-null.
208 + *
209 + * <p><em>jsr166e note: During transition, this class
210 + * uses nested functional interfaces with different names but the
211 + * same forms as those expected for JDK8.</em>
212 + *
213   * <p>This class is a member of the
214   * <a href="{@docRoot}/../technotes/guides/collections/index.html">
215   * Java Collections Framework</a>.
216   *
90 * <p><em>jsr166e note: This class is a candidate replacement for
91 * java.util.concurrent.ConcurrentHashMap.<em>
92 *
217   * @since 1.5
218   * @author Doug Lea
219   * @param <K> the type of keys maintained by this map
220   * @param <V> the type of mapped values
221   */
222 < public class ConcurrentHashMapV8<K, V>
223 <        implements ConcurrentMap<K, V>, Serializable {
222 > public class ConcurrentHashMapV8<K,V> extends AbstractMap<K,V>
223 >    implements ConcurrentMap<K,V>, Serializable {
224      private static final long serialVersionUID = 7249069246763182397L;
225  
226      /**
227 <     * A function computing a mapping from the given key to a value.
228 <     * This is a place-holder for an upcoming JDK8 interface.
227 >     * An object for traversing and partitioning elements of a source.
228 >     * This interface provides a subset of the functionality of JDK8
229 >     * java.util.Spliterator.
230       */
231 <    public static interface MappingFunction<K, V> {
231 >    public static interface ConcurrentHashMapSpliterator<T> {
232          /**
233 <         * Returns a value for the given key, or null if there is no mapping.
234 <         *
235 <         * @param key the (non-null) key
236 <         * @return a value for the key, or null if none
233 >         * If possible, returns a new spliterator covering
234 >         * approximately one half of the elements, which will not be
235 >         * covered by this spliterator. Returns null if cannot be
236 >         * split.
237           */
238 <        V map(K key);
114 <    }
115 <
116 <    /**
117 <     * A function computing a new mapping given a key and its current
118 <     * mapped value (or {@code null} if there is no current
119 <     * mapping). This is a place-holder for an upcoming JDK8
120 <     * interface.
121 <     */
122 <    public static interface RemappingFunction<K, V> {
238 >        ConcurrentHashMapSpliterator<T> trySplit();
239          /**
240 <         * Returns a new value given a key and its current value.
241 <         *
126 <         * @param key the (non-null) key
127 <         * @param value the current value, or null if there is no mapping
128 <         * @return a value for the key, or null if none
129 <         */
130 <        V remap(K key, V value);
131 <    }
132 <
133 <    /**
134 <     * A partitionable iterator. A Spliterator can be traversed
135 <     * directly, but can also be partitioned (before traversal) by
136 <     * creating another Spliterator that covers a non-overlapping
137 <     * portion of the elements, and so may be amenable to parallel
138 <     * execution.
139 <     *
140 <     * <p> This interface exports a subset of expected JDK8
141 <     * functionality.
142 <     *
143 <     * <p>Sample usage: Here is one (of the several) ways to compute
144 <     * the sum of the values held in a map using the ForkJoin
145 <     * framework. As illustrated here, Spliterators are well suited to
146 <     * designs in which a task repeatedly splits off half its work
147 <     * into forked subtasks until small enough to process directly,
148 <     * and then joins these subtasks. Variants of this style can also
149 <     * be used in completion-based designs.
150 <     *
151 <     * <pre>
152 <     * {@code ConcurrentHashMapV8<String, Long> m = ...
153 <     * // Uses parallel depth of log2 of size / (parallelism * slack of 8).
154 <     * int depth = 32 - Integer.numberOfLeadingZeros(m.size() / (aForkJoinPool.getParallelism() * 8));
155 <     * long sum = aForkJoinPool.invoke(new SumValues(m.valueSpliterator(), depth, null));
156 <     * // ...
157 <     * static class SumValues extends RecursiveTask<Long> {
158 <     *   final Spliterator<Long> s;
159 <     *   final int depth;             // number of splits before processing
160 <     *   final SumValues nextJoin;    // records forked subtasks to join
161 <     *   SumValues(Spliterator<Long> s, int depth, SumValues nextJoin) {
162 <     *     this.s = s; this.depth = depth; this.nextJoin = nextJoin;
163 <     *   }
164 <     *   public Long compute() {
165 <     *     long sum = 0;
166 <     *     SumValues subtasks = null; // fork subtasks
167 <     *     for (int d = depth - 1; d >= 0; --d)
168 <     *       (subtasks = new SumValues(s.split(), d, subtasks)).fork();
169 <     *     while (s.hasNext())        // directly process remaining elements
170 <     *       sum += s.next();
171 <     *     for (SumValues t = subtasks; t != null; t = t.nextJoin)
172 <     *       sum += t.join();         // collect subtask results
173 <     *     return sum;
174 <     *   }
175 <     * }
176 <     * }</pre>
177 <     */
178 <    public static interface Spliterator<T> extends Iterator<T> {
179 <        /**
180 <         * Returns a Spliterator covering approximately half of the
181 <         * elements, guaranteed not to overlap with those subsequently
182 <         * returned by this Spliterator.  After invoking this method,
183 <         * the current Spliterator will <em>not</em> produce any of
184 <         * the elements of the returned Spliterator, but the two
185 <         * Spliterators together will produce all of the elements that
186 <         * would have been produced by this Spliterator had this
187 <         * method not been called. The exact number of elements
188 <         * produced by the returned Spliterator is not guaranteed, and
189 <         * may be zero (i.e., with {@code hasNext()} reporting {@code
190 <         * false}) if this Spliterator cannot be further split.
191 <         *
192 <         * @return a Spliterator covering approximately half of the
193 <         * elements
194 <         * @throws IllegalStateException if this Spliterator has
195 <         * already commenced traversing elements
240 >         * Returns an estimate of the number of elements covered by
241 >         * this Spliterator.
242           */
243 <        Spliterator<T> split();
244 <    }
243 >        long estimateSize();
244 >
245 >        /** Applies the action to each untraversed element */
246 >        void forEachRemaining(Action<? super T> action);
247 >        /** If an element remains, applies the action and returns true. */
248 >        boolean tryAdvance(Action<? super T> action);
249 >    }
250 >
251 >    // Sams
252 >    /** Interface describing a void action of one argument */
253 >    public interface Action<A> { void apply(A a); }
254 >    /** Interface describing a void action of two arguments */
255 >    public interface BiAction<A,B> { void apply(A a, B b); }
256 >    /** Interface describing a function of one argument */
257 >    public interface Fun<A,T> { T apply(A a); }
258 >    /** Interface describing a function of two arguments */
259 >    public interface BiFun<A,B,T> { T apply(A a, B b); }
260 >    /** Interface describing a function mapping its argument to a double */
261 >    public interface ObjectToDouble<A> { double apply(A a); }
262 >    /** Interface describing a function mapping its argument to a long */
263 >    public interface ObjectToLong<A> { long apply(A a); }
264 >    /** Interface describing a function mapping its argument to an int */
265 >    public interface ObjectToInt<A> {int apply(A a); }
266 >    /** Interface describing a function mapping two arguments to a double */
267 >    public interface ObjectByObjectToDouble<A,B> { double apply(A a, B b); }
268 >    /** Interface describing a function mapping two arguments to a long */
269 >    public interface ObjectByObjectToLong<A,B> { long apply(A a, B b); }
270 >    /** Interface describing a function mapping two arguments to an int */
271 >    public interface ObjectByObjectToInt<A,B> {int apply(A a, B b); }
272 >    /** Interface describing a function mapping two doubles to a double */
273 >    public interface DoubleByDoubleToDouble { double apply(double a, double b); }
274 >    /** Interface describing a function mapping two longs to a long */
275 >    public interface LongByLongToLong { long apply(long a, long b); }
276 >    /** Interface describing a function mapping two ints to an int */
277 >    public interface IntByIntToInt { int apply(int a, int b); }
278  
279      /*
280       * Overview:
# Line 207 | Line 286 | public class ConcurrentHashMapV8<K, V>
286       * the same or better than java.util.HashMap, and to support high
287       * initial insertion rates on an empty table by many threads.
288       *
289 <     * Each key-value mapping is held in a Node.  Because Node fields
290 <     * can contain special values, they are defined using plain Object
291 <     * types. Similarly in turn, all internal methods that use them
292 <     * work off Object types. And similarly, so do the internal
293 <     * methods of auxiliary iterator and view classes.  All public
294 <     * generic typed methods relay in/out of these internal methods,
295 <     * supplying null-checks and casts as needed. This also allows
296 <     * many of the public methods to be factored into a smaller number
297 <     * of internal methods (although sadly not so for the five
298 <     * variants of put-related operations). The validation-based
299 <     * approach explained below leads to a lot of code sprawl because
300 <     * retry-control precludes factoring into smaller methods.
289 >     * This map usually acts as a binned (bucketed) hash table.  Each
290 >     * key-value mapping is held in a Node.  Most nodes are instances
291 >     * of the basic Node class with hash, key, value, and next
292 >     * fields. However, various subclasses exist: TreeNodes are
293 >     * arranged in balanced trees, not lists.  TreeBins hold the roots
294 >     * of sets of TreeNodes. ForwardingNodes are placed at the heads
295 >     * of bins during resizing. ReservationNodes are used as
296 >     * placeholders while establishing values in computeIfAbsent and
297 >     * related methods.  The types TreeBin, ForwardingNode, and
298 >     * ReservationNode do not hold normal user keys, values, or
299 >     * hashes, and are readily distinguishable during search etc
300 >     * because they have negative hash fields and null key and value
301 >     * fields. (These special nodes are either uncommon or transient,
302 >     * so the impact of carrying around some unused fields is
303 >     * insignificant.)
304       *
305       * The table is lazily initialized to a power-of-two size upon the
306       * first insertion.  Each bin in the table normally contains a
# Line 226 | Line 308 | public class ConcurrentHashMapV8<K, V>
308       * Table accesses require volatile/atomic reads, writes, and
309       * CASes.  Because there is no other way to arrange this without
310       * adding further indirections, we use intrinsics
311 <     * (sun.misc.Unsafe) operations.  The lists of nodes within bins
312 <     * are always accurately traversable under volatile reads, so long
313 <     * as lookups check hash code and non-nullness of value before
314 <     * checking key equality.
315 <     *
316 <     * We use the top two bits of Node hash fields for control
235 <     * purposes -- they are available anyway because of addressing
236 <     * constraints.  As explained further below, these top bits are
237 <     * used as follows:
238 <     *  00 - Normal
239 <     *  01 - Locked
240 <     *  11 - Locked and may have a thread waiting for lock
241 <     *  10 - Node is a forwarding node
242 <     *
243 <     * The lower 30 bits of each Node's hash field contain a
244 <     * transformation of the key's hash code, except for forwarding
245 <     * nodes, for which the lower bits are zero (and so always have
246 <     * hash field == MOVED).
311 >     * (sun.misc.Unsafe) operations.
312 >     *
313 >     * We use the top (sign) bit of Node hash fields for control
314 >     * purposes -- it is available anyway because of addressing
315 >     * constraints.  Nodes with negative hash fields are specially
316 >     * handled or ignored in map methods.
317       *
318       * Insertion (via put or its variants) of the first node in an
319       * empty bin is performed by just CASing it to the bin.  This is
# Line 252 | Line 322 | public class ConcurrentHashMapV8<K, V>
322       * delete, and replace) require locks.  We do not want to waste
323       * the space required to associate a distinct lock object with
324       * each bin, so instead use the first node of a bin list itself as
325 <     * a lock. Blocking support for these locks relies on the builtin
326 <     * "synchronized" monitors.  However, we also need a tryLock
257 <     * construction, so we overlay these by using bits of the Node
258 <     * hash field for lock control (see above), and so normally use
259 <     * builtin monitors only for blocking and signalling using
260 <     * wait/notifyAll constructions. See Node.tryAwaitLock.
325 >     * a lock. Locking support for these locks relies on builtin
326 >     * "synchronized" monitors.
327       *
328       * Using the first node of a list as a lock does not by itself
329       * suffice though: When a node is locked, any update must first
330       * validate that it is still the first node after locking it, and
331       * retry if not. Because new nodes are always appended to lists,
332       * once a node is first in a bin, it remains first until deleted
333 <     * or the bin becomes invalidated (upon resizing).  However,
268 <     * operations that only conditionally update may inspect nodes
269 <     * until the point of update. This is a converse of sorts to the
270 <     * lazy locking technique described by Herlihy & Shavit.
333 >     * or the bin becomes invalidated (upon resizing).
334       *
335       * The main disadvantage of per-bin locks is that other update
336       * operations on other nodes in a bin list protected by the same
# Line 300 | Line 363 | public class ConcurrentHashMapV8<K, V>
363       * sometimes deviate significantly from uniform randomness.  This
364       * includes the case when N > (1<<30), so some keys MUST collide.
365       * Similarly for dumb or hostile usages in which multiple keys are
366 <     * designed to have identical hash codes. Also, although we guard
367 <     * against the worst effects of this (see method spread), sets of
368 <     * hashes may differ only in bits that do not impact their bin
369 <     * index for a given power-of-two mask.  So we use a secondary
370 <     * strategy that applies when the number of nodes in a bin exceeds
371 <     * a threshold, and at least one of the keys implements
309 <     * Comparable.  These TreeBins use a balanced tree to hold nodes
310 <     * (a specialized form of red-black trees), bounding search time
311 <     * to O(log N).  Each search step in a TreeBin is around twice as
366 >     * designed to have identical hash codes or ones that differs only
367 >     * in masked-out high bits. So we use a secondary strategy that
368 >     * applies when the number of nodes in a bin exceeds a
369 >     * threshold. These TreeBins use a balanced tree to hold nodes (a
370 >     * specialized form of red-black trees), bounding search time to
371 >     * O(log N).  Each search step in a TreeBin is at least twice as
372       * slow as in a regular list, but given that N cannot exceed
373       * (1<<64) (before running out of addresses) this bounds search
374       * steps, lock hold times, etc, to reasonable constants (roughly
# Line 319 | Line 379 | public class ConcurrentHashMapV8<K, V>
379       * iterators in the same way.
380       *
381       * The table is resized when occupancy exceeds a percentage
382 <     * threshold (nominally, 0.75, but see below).  Only a single
383 <     * thread performs the resize (using field "sizeCtl", to arrange
384 <     * exclusion), but the table otherwise remains usable for reads
385 <     * and updates. Resizing proceeds by transferring bins, one by
386 <     * one, from the table to the next table.  Because we are using
387 <     * power-of-two expansion, the elements from each bin must either
388 <     * stay at same index, or move with a power of two offset. We
389 <     * eliminate unnecessary node creation by catching cases where old
390 <     * nodes can be reused because their next fields won't change.  On
391 <     * average, only about one-sixth of them need cloning when a table
392 <     * doubles. The nodes they replace will be garbage collectable as
393 <     * soon as they are no longer referenced by any reader thread that
394 <     * may be in the midst of concurrently traversing table.  Upon
395 <     * transfer, the old table bin contains only a special forwarding
396 <     * node (with hash field "MOVED") that contains the next table as
397 <     * its key. On encountering a forwarding node, access and update
398 <     * operations restart, using the new table.
399 <     *
400 <     * Each bin transfer requires its bin lock. However, unlike other
401 <     * cases, a transfer can skip a bin if it fails to acquire its
402 <     * lock, and revisit it later (unless it is a TreeBin). Method
403 <     * rebuild maintains a buffer of TRANSFER_BUFFER_SIZE bins that
404 <     * have been skipped because of failure to acquire a lock, and
405 <     * blocks only if none are available (i.e., only very rarely).
406 <     * The transfer operation must also ensure that all accessible
407 <     * bins in both the old and new table are usable by any traversal.
408 <     * When there are no lock acquisition failures, this is arranged
409 <     * simply by proceeding from the last bin (table.length - 1) up
410 <     * towards the first.  Upon seeing a forwarding node, traversals
411 <     * (see class InternalIterator) arrange to move to the new table
412 <     * without revisiting nodes.  However, when any node is skipped
413 <     * during a transfer, all earlier table bins may have become
414 <     * visible, so are initialized with a reverse-forwarding node back
415 <     * to the old table until the new ones are established. (This
416 <     * sometimes requires transiently locking a forwarding node, which
417 <     * is possible under the above encoding.) These more expensive
418 <     * mechanics trigger only when necessary.
382 >     * threshold (nominally, 0.75, but see below).  Any thread
383 >     * noticing an overfull bin may assist in resizing after the
384 >     * initiating thread allocates and sets up the replacement
385 >     * array. However, rather than stalling, these other threads may
386 >     * proceed with insertions etc.  The use of TreeBins shields us
387 >     * from the worst case effects of overfilling while resizes are in
388 >     * progress.  Resizing proceeds by transferring bins, one by one,
389 >     * from the table to the next table. To enable concurrency, the
390 >     * next table must be (incrementally) prefilled with place-holders
391 >     * serving as reverse forwarders to the old table.  Because we are
392 >     * using power-of-two expansion, the elements from each bin must
393 >     * either stay at same index, or move with a power of two
394 >     * offset. We eliminate unnecessary node creation by catching
395 >     * cases where old nodes can be reused because their next fields
396 >     * won't change.  On average, only about one-sixth of them need
397 >     * cloning when a table doubles. The nodes they replace will be
398 >     * garbage collectable as soon as they are no longer referenced by
399 >     * any reader thread that may be in the midst of concurrently
400 >     * traversing table.  Upon transfer, the old table bin contains
401 >     * only a special forwarding node (with hash field "MOVED") that
402 >     * contains the next table as its key. On encountering a
403 >     * forwarding node, access and update operations restart, using
404 >     * the new table.
405 >     *
406 >     * Each bin transfer requires its bin lock, which can stall
407 >     * waiting for locks while resizing. However, because other
408 >     * threads can join in and help resize rather than contend for
409 >     * locks, average aggregate waits become shorter as resizing
410 >     * progresses.  The transfer operation must also ensure that all
411 >     * accessible bins in both the old and new table are usable by any
412 >     * traversal.  This is arranged by proceeding from the last bin
413 >     * (table.length - 1) up towards the first.  Upon seeing a
414 >     * forwarding node, traversals (see class Traverser) arrange to
415 >     * move to the new table without revisiting nodes.  However, to
416 >     * ensure that no intervening nodes are skipped, bin splitting can
417 >     * only begin after the associated reverse-forwarders are in
418 >     * place.
419       *
420       * The traversal scheme also applies to partial traversals of
421 <     * ranges of bins (via an alternate InternalIterator constructor)
421 >     * ranges of bins (via an alternate Traverser constructor)
422       * to support partitioned aggregate operations.  Also, read-only
423       * operations give up if ever forwarded to a null table, which
424       * provides support for shutdown-style clearing, which is also not
# Line 370 | Line 430 | public class ConcurrentHashMapV8<K, V>
430       * These cases attempt to override the initial capacity settings,
431       * but harmlessly fail to take effect in cases of races.
432       *
433 <     * The element count is maintained using a LongAdder, which avoids
434 <     * contention on updates but can encounter cache thrashing if read
435 <     * too frequently during concurrent access. To avoid reading so
436 <     * often, resizing is attempted either when a bin lock is
437 <     * contended, or upon adding to a bin already holding two or more
438 <     * nodes (checked before adding in the xIfAbsent methods, after
439 <     * adding in others). Under uniform hash distributions, the
440 <     * probability of this occurring at threshold is around 13%,
441 <     * meaning that only about 1 in 8 puts check threshold (and after
442 <     * resizing, many fewer do so). But this approximation has high
443 <     * variance for small table sizes, so we check on any collision
444 <     * for sizes <= 64. The bulk putAll operation further reduces
445 <     * contention by only committing count updates upon these size
446 <     * checks.
433 >     * The element count is maintained using a specialization of
434 >     * LongAdder. We need to incorporate a specialization rather than
435 >     * just use a LongAdder in order to access implicit
436 >     * contention-sensing that leads to creation of multiple
437 >     * CounterCells.  The counter mechanics avoid contention on
438 >     * updates but can encounter cache thrashing if read too
439 >     * frequently during concurrent access. To avoid reading so often,
440 >     * resizing under contention is attempted only upon adding to a
441 >     * bin already holding two or more nodes. Under uniform hash
442 >     * distributions, the probability of this occurring at threshold
443 >     * is around 13%, meaning that only about 1 in 8 puts check
444 >     * threshold (and after resizing, many fewer do so).
445 >     *
446 >     * TreeBins use a special form of comparison for search and
447 >     * related operations (which is the main reason we cannot use
448 >     * existing collections such as TreeMaps). TreeBins contain
449 >     * Comparable elements, but may contain others, as well as
450 >     * elements that are Comparable but not necessarily Comparable for
451 >     * the same T, so we cannot invoke compareTo among them. To handle
452 >     * this, the tree is ordered primarily by hash value, then by
453 >     * Comparable.compareTo order if applicable.  On lookup at a node,
454 >     * if elements are not comparable or compare as 0 then both left
455 >     * and right children may need to be searched in the case of tied
456 >     * hash values. (This corresponds to the full list search that
457 >     * would be necessary if all elements were non-Comparable and had
458 >     * tied hashes.) On insertion, to keep a total ordering (or as
459 >     * close as is required here) across rebalancings, we compare
460 >     * classes and identityHashCodes as tie-breakers. The red-black
461 >     * balancing code is updated from pre-jdk-collections
462 >     * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
463 >     * based in turn on Cormen, Leiserson, and Rivest "Introduction to
464 >     * Algorithms" (CLR).
465 >     *
466 >     * TreeBins also require an additional locking mechanism.  While
467 >     * list traversal is always possible by readers even during
468 >     * updates, tree traversal is not, mainly because of tree-rotations
469 >     * that may change the root node and/or its linkages.  TreeBins
470 >     * include a simple read-write lock mechanism parasitic on the
471 >     * main bin-synchronization strategy: Structural adjustments
472 >     * associated with an insertion or removal are already bin-locked
473 >     * (and so cannot conflict with other writers) but must wait for
474 >     * ongoing readers to finish. Since there can be only one such
475 >     * waiter, we use a simple scheme using a single "waiter" field to
476 >     * block writers.  However, readers need never block.  If the root
477 >     * lock is held, they proceed along the slow traversal path (via
478 >     * next-pointers) until the lock becomes available or the list is
479 >     * exhausted, whichever comes first. These cases are not fast, but
480 >     * maximize aggregate expected throughput.
481       *
482       * Maintaining API and serialization compatibility with previous
483       * versions of this class introduces several oddities. Mainly: We
# Line 393 | Line 487 | public class ConcurrentHashMapV8<K, V>
487       * time that we can guarantee to honor it.) We also declare an
488       * unused "Segment" class that is instantiated in minimal form
489       * only when serializing.
490 +     *
491 +     * Also, solely for compatibility with previous versions of this
492 +     * class, it extends AbstractMap, even though all of its methods
493 +     * are overridden, so it is just useless baggage.
494 +     *
495 +     * This file is organized to make things a little easier to follow
496 +     * while reading than they might otherwise: First the main static
497 +     * declarations and utilities, then fields, then main public
498 +     * methods (with a few factorings of multiple public methods into
499 +     * internal ones), then sizing methods, trees, traversers, and
500 +     * bulk operations.
501       */
502  
503      /* ---------------- Constants -------------- */
# Line 434 | Line 539 | public class ConcurrentHashMapV8<K, V>
539      private static final float LOAD_FACTOR = 0.75f;
540  
541      /**
437     * The buffer size for skipped bins during transfers. The
438     * value is arbitrary but should be large enough to avoid
439     * most locking stalls during resizes.
440     */
441    private static final int TRANSFER_BUFFER_SIZE = 32;
442
443    /**
542       * The bin count threshold for using a tree rather than list for a
543 <     * bin.  The value reflects the approximate break-even point for
544 <     * using tree-based operations.
545 <     */
546 <    private static final int TREE_THRESHOLD = 8;
547 <
450 <    /*
451 <     * Encodings for special uses of Node hash fields. See above for
452 <     * explanation.
543 >     * bin.  Bins are converted to trees when adding an element to a
544 >     * bin with at least this many nodes. The value must be greater
545 >     * than 2, and should be at least 8 to mesh with assumptions in
546 >     * tree removal about conversion back to plain bins upon
547 >     * shrinkage.
548       */
549 <    static final int MOVED     = 0x80000000; // hash field for forwarding nodes
455 <    static final int LOCKED    = 0x40000000; // set/tested only as a bit
456 <    static final int WAITING   = 0xc0000000; // both bits set/tested together
457 <    static final int HASH_BITS = 0x3fffffff; // usable bits of normal node hash
458 <
459 <    /* ---------------- Fields -------------- */
549 >    static final int TREEIFY_THRESHOLD = 8;
550  
551      /**
552 <     * The array of bins. Lazily initialized upon first insertion.
553 <     * Size is always a power of two. Accessed directly by iterators.
552 >     * The bin count threshold for untreeifying a (split) bin during a
553 >     * resize operation. Should be less than TREEIFY_THRESHOLD, and at
554 >     * most 6 to mesh with shrinkage detection under removal.
555       */
556 <    transient volatile Node[] table;
556 >    static final int UNTREEIFY_THRESHOLD = 6;
557  
558      /**
559 <     * The counter maintaining number of elements.
559 >     * The smallest table capacity for which bins may be treeified.
560 >     * (Otherwise the table is resized if too many nodes in a bin.)
561 >     * The value should be at least 4 * TREEIFY_THRESHOLD to avoid
562 >     * conflicts between resizing and treeification thresholds.
563       */
564 <    private transient final LongAdder counter;
564 >    static final int MIN_TREEIFY_CAPACITY = 64;
565  
566      /**
567 <     * Table initialization and resizing control.  When negative, the
568 <     * table is being initialized or resized. Otherwise, when table is
569 <     * null, holds the initial table size to use upon creation, or 0
570 <     * for default. After initialization, holds the next element count
571 <     * value upon which to resize the table.
567 >     * Minimum number of rebinnings per transfer step. Ranges are
568 >     * subdivided to allow multiple resizer threads.  This value
569 >     * serves as a lower bound to avoid resizers encountering
570 >     * excessive memory contention.  The value should be at least
571 >     * DEFAULT_CAPACITY.
572       */
573 <    private transient volatile int sizeCtl;
480 <
481 <    // views
482 <    private transient KeySet<K,V> keySet;
483 <    private transient Values<K,V> values;
484 <    private transient EntrySet<K,V> entrySet;
485 <
486 <    /** For serialization compatibility. Null unless serialized; see below */
487 <    private Segment<K,V>[] segments;
488 <
489 <    /* ---------------- Table element access -------------- */
573 >    private static final int MIN_TRANSFER_STRIDE = 16;
574  
575      /*
576 <     * Volatile access methods are used for table elements as well as
493 <     * elements of in-progress next table while resizing.  Uses are
494 <     * null checked by callers, and implicitly bounds-checked, relying
495 <     * on the invariants that tab arrays have non-zero size, and all
496 <     * indices are masked with (tab.length - 1) which is never
497 <     * negative and always less than length. Note that, to be correct
498 <     * wrt arbitrary concurrency errors by users, bounds checks must
499 <     * operate on local variables, which accounts for some odd-looking
500 <     * inline assignments below.
576 >     * Encodings for Node hash fields. See above for explanation.
577       */
578 <
579 <    static final Node tabAt(Node[] tab, int i) { // used by InternalIterator
580 <        return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE);
581 <    }
582 <
583 <    private static final boolean casTabAt(Node[] tab, int i, Node c, Node v) {
584 <        return UNSAFE.compareAndSwapObject(tab, ((long)i<<ASHIFT)+ABASE, c, v);
585 <    }
586 <
587 <    private static final void setTabAt(Node[] tab, int i, Node v) {
588 <        UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v);
589 <    }
578 >    static final int MOVED     = -1; // hash for forwarding nodes
579 >    static final int TREEBIN   = -2; // hash for roots of trees
580 >    static final int RESERVED  = -3; // hash for transient reservations
581 >    static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
582 >
583 >    /** Number of CPUS, to place bounds on some sizings */
584 >    static final int NCPU = Runtime.getRuntime().availableProcessors();
585 >
586 >    /** For serialization compatibility. */
587 >    private static final ObjectStreamField[] serialPersistentFields = {
588 >        new ObjectStreamField("segments", Segment[].class),
589 >        new ObjectStreamField("segmentMask", Integer.TYPE),
590 >        new ObjectStreamField("segmentShift", Integer.TYPE)
591 >    };
592  
593      /* ---------------- Nodes -------------- */
594  
595      /**
596 <     * Key-value entry. Note that this is never exported out as a
597 <     * user-visible Map.Entry (see MapEntry below). Nodes with a hash
598 <     * field of MOVED are special, and do not contain user keys or
599 <     * values.  Otherwise, keys are never null, and null val fields
600 <     * indicate that a node is in the process of being deleted or
601 <     * created. For purposes of read-only access, a key may be read
602 <     * before a val, but can only be used after checking val to be
603 <     * non-null.
604 <     */
605 <    static class Node {
606 <        volatile int hash;
607 <        final Object key;
530 <        volatile Object val;
531 <        volatile Node next;
596 >     * Key-value entry.  This class is never exported out as a
597 >     * user-mutable Map.Entry (i.e., one supporting setValue; see
598 >     * MapEntry below), but can be used for read-only traversals used
599 >     * in bulk tasks.  Subclasses of Node with a negative hash field
600 >     * are special, and contain null keys and values (but are never
601 >     * exported).  Otherwise, keys and vals are never null.
602 >     */
603 >    static class Node<K,V> implements Map.Entry<K,V> {
604 >        final int hash;
605 >        final K key;
606 >        volatile V val;
607 >        volatile Node<K,V> next;
608  
609 <        Node(int hash, Object key, Object val, Node next) {
609 >        Node(int hash, K key, V val, Node<K,V> next) {
610              this.hash = hash;
611              this.key = key;
612              this.val = val;
613              this.next = next;
614          }
615  
616 <        /** CompareAndSet the hash field */
617 <        final boolean casHash(int cmp, int val) {
618 <            return UNSAFE.compareAndSwapInt(this, hashOffset, cmp, val);
619 <        }
620 <
621 <        /** The number of spins before blocking for a lock */
546 <        static final int MAX_SPINS =
547 <            Runtime.getRuntime().availableProcessors() > 1 ? 64 : 1;
548 <
549 <        /**
550 <         * Spins a while if LOCKED bit set and this node is the first
551 <         * of its bin, and then sets WAITING bits on hash field and
552 <         * blocks (once) if they are still set.  It is OK for this
553 <         * method to return even if lock is not available upon exit,
554 <         * which enables these simple single-wait mechanics.
555 <         *
556 <         * The corresponding signalling operation is performed within
557 <         * callers: Upon detecting that WAITING has been set when
558 <         * unlocking lock (via a failed CAS from non-waiting LOCKED
559 <         * state), unlockers acquire the sync lock and perform a
560 <         * notifyAll.
561 <         */
562 <        final void tryAwaitLock(Node[] tab, int i) {
563 <            if (tab != null && i >= 0 && i < tab.length) { // bounds check
564 <                int r = ThreadLocalRandom.current().nextInt(); // randomize spins
565 <                int spins = MAX_SPINS, h;
566 <                while (tabAt(tab, i) == this && ((h = hash) & LOCKED) != 0) {
567 <                    if (spins >= 0) {
568 <                        r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
569 <                        if (r >= 0 && --spins == 0)
570 <                            Thread.yield();  // yield before block
571 <                    }
572 <                    else if (casHash(h, h | WAITING)) {
573 <                        synchronized (this) {
574 <                            if (tabAt(tab, i) == this &&
575 <                                (hash & WAITING) == WAITING) {
576 <                                try {
577 <                                    wait();
578 <                                } catch (InterruptedException ie) {
579 <                                    Thread.currentThread().interrupt();
580 <                                }
581 <                            }
582 <                            else
583 <                                notifyAll(); // possibly won race vs signaller
584 <                        }
585 <                        break;
586 <                    }
587 <                }
588 <            }
589 <        }
590 <
591 <        // Unsafe mechanics for casHash
592 <        private static final sun.misc.Unsafe UNSAFE;
593 <        private static final long hashOffset;
594 <
595 <        static {
596 <            try {
597 <                UNSAFE = getUnsafe();
598 <                Class<?> k = Node.class;
599 <                hashOffset = UNSAFE.objectFieldOffset
600 <                    (k.getDeclaredField("hash"));
601 <            } catch (Exception e) {
602 <                throw new Error(e);
603 <            }
604 <        }
605 <    }
606 <
607 <    /* ---------------- TreeBins -------------- */
608 <
609 <    /**
610 <     * Nodes for use in TreeBins
611 <     */
612 <    static final class TreeNode extends Node {
613 <        TreeNode parent;  // red-black tree links
614 <        TreeNode left;
615 <        TreeNode right;
616 <        TreeNode prev;    // needed to unlink next upon deletion
617 <        boolean red;
618 <
619 <        TreeNode(int hash, Object key, Object val, Node next, TreeNode parent) {
620 <            super(hash, key, val, next);
621 <            this.parent = parent;
622 <        }
623 <    }
624 <
625 <    /**
626 <     * A specialized form of red-black tree for use in bins
627 <     * whose size exceeds a threshold.
628 <     *
629 <     * TreeBins use a special form of comparison for search and
630 <     * related operations (which is the main reason we cannot use
631 <     * existing collections such as TreeMaps). TreeBins contain
632 <     * Comparable elements, but may contain others, as well as
633 <     * elements that are Comparable but not necessarily Comparable<T>
634 <     * for the same T, so we cannot invoke compareTo among them. To
635 <     * handle this, the tree is ordered primarily by hash value, then
636 <     * by getClass().getName() order, and then by Comparator order
637 <     * among elements of the same class.  On lookup at a node, if
638 <     * elements are not comparable or compare as 0, both left and
639 <     * right children may need to be searched in the case of tied hash
640 <     * values. (This corresponds to the full list search that would be
641 <     * necessary if all elements were non-Comparable and had tied
642 <     * hashes.)  The red-black balancing code is updated from
643 <     * pre-jdk-collections
644 <     * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
645 <     * based in turn on Cormen, Leiserson, and Rivest "Introduction to
646 <     * Algorithms" (CLR).
647 <     *
648 <     * TreeBins also maintain a separate locking discipline than
649 <     * regular bins. Because they are forwarded via special MOVED
650 <     * nodes at bin heads (which can never change once established),
651 <     * we cannot use use those nodes as locks. Instead, TreeBin
652 <     * extends AbstractQueuedSynchronizer to support a simple form of
653 <     * read-write lock. For update operations and table validation,
654 <     * the exclusive form of lock behaves in the same way as bin-head
655 <     * locks. However, lookups use shared read-lock mechanics to allow
656 <     * multiple readers in the absence of writers.  Additionally,
657 <     * these lookups do not ever block: While the lock is not
658 <     * available, they proceed along the slow traversal path (via
659 <     * next-pointers) until the lock becomes available or the list is
660 <     * exhausted, whichever comes first. (These cases are not fast,
661 <     * but maximize aggregate expected throughput.)  The AQS mechanics
662 <     * for doing this are straightforward.  The lock state is held as
663 <     * AQS getState().  Read counts are negative; the write count (1)
664 <     * is positive.  There are no signalling preferences among readers
665 <     * and writers. Since we don't need to export full Lock API, we
666 <     * just override the minimal AQS methods and use them directly.
667 <     */
668 <    static final class TreeBin extends AbstractQueuedSynchronizer {
669 <        private static final long serialVersionUID = 2249069246763182397L;
670 <        transient TreeNode root;  // root of tree
671 <        transient TreeNode first; // head of next-pointer list
672 <
673 <        /* AQS overrides */
674 <        public final boolean isHeldExclusively() { return getState() > 0; }
675 <        public final boolean tryAcquire(int ignore) {
676 <            if (compareAndSetState(0, 1)) {
677 <                setExclusiveOwnerThread(Thread.currentThread());
678 <                return true;
679 <            }
680 <            return false;
681 <        }
682 <        public final boolean tryRelease(int ignore) {
683 <            setExclusiveOwnerThread(null);
684 <            setState(0);
685 <            return true;
686 <        }
687 <        public final int tryAcquireShared(int ignore) {
688 <            for (int c;;) {
689 <                if ((c = getState()) > 0)
690 <                    return -1;
691 <                if (compareAndSetState(c, c -1))
692 <                    return 1;
693 <            }
694 <        }
695 <        public final boolean tryReleaseShared(int ignore) {
696 <            int c;
697 <            do {} while (!compareAndSetState(c = getState(), c + 1));
698 <            return c == -1;
699 <        }
700 <
701 <        /** From CLR */
702 <        private void rotateLeft(TreeNode p) {
703 <            if (p != null) {
704 <                TreeNode r = p.right, pp, rl;
705 <                if ((rl = p.right = r.left) != null)
706 <                    rl.parent = p;
707 <                if ((pp = r.parent = p.parent) == null)
708 <                    root = r;
709 <                else if (pp.left == p)
710 <                    pp.left = r;
711 <                else
712 <                    pp.right = r;
713 <                r.left = p;
714 <                p.parent = r;
715 <            }
716 <        }
717 <
718 <        /** From CLR */
719 <        private void rotateRight(TreeNode p) {
720 <            if (p != null) {
721 <                TreeNode l = p.left, pp, lr;
722 <                if ((lr = p.left = l.right) != null)
723 <                    lr.parent = p;
724 <                if ((pp = l.parent = p.parent) == null)
725 <                    root = l;
726 <                else if (pp.right == p)
727 <                    pp.right = l;
728 <                else
729 <                    pp.left = l;
730 <                l.right = p;
731 <                p.parent = l;
732 <            }
733 <        }
734 <
735 <        /**
736 <         * Return the TreeNode (or null if not found) for the given key
737 <         * starting at given root.
738 <         */
739 <        @SuppressWarnings("unchecked") // suppress Comparable cast warning
740 <        final TreeNode getTreeNode(int h, Object k, TreeNode p) {
741 <            Class<?> c = k.getClass();
742 <            while (p != null) {
743 <                int dir, ph;  Object pk; Class<?> pc;
744 <                if ((ph = p.hash) == h) {
745 <                    if ((pk = p.key) == k || k.equals(pk))
746 <                        return p;
747 <                    if (c != (pc = pk.getClass()) ||
748 <                        !(k instanceof Comparable) ||
749 <                        (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
750 <                        dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName());
751 <                        TreeNode r = null, s = null, pl, pr;
752 <                        if (dir >= 0) {
753 <                            if ((pl = p.left) != null && h <= pl.hash)
754 <                                s = pl;
755 <                        }
756 <                        else if ((pr = p.right) != null && h >= pr.hash)
757 <                            s = pr;
758 <                        if (s != null && (r = getTreeNode(h, k, s)) != null)
759 <                            return r;
760 <                    }
761 <                }
762 <                else
763 <                    dir = (h < ph) ? -1 : 1;
764 <                p = (dir > 0) ? p.right : p.left;
765 <            }
766 <            return null;
616 >        public final K getKey()       { return key; }
617 >        public final V getValue()     { return val; }
618 >        public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
619 >        public final String toString(){ return key + "=" + val; }
620 >        public final V setValue(V value) {
621 >            throw new UnsupportedOperationException();
622          }
623  
624 <        /**
625 <         * Wrapper for getTreeNode used by CHM.get. Tries to obtain
626 <         * read-lock to call getTreeNode, but during failure to get
627 <         * lock, searches along next links.
628 <         */
629 <        final Object getValue(int h, Object k) {
630 <            Node r = null;
776 <            int c = getState(); // Must read lock state first
777 <            for (Node e = first; e != null; e = e.next) {
778 <                if (c <= 0 && compareAndSetState(c, c - 1)) {
779 <                    try {
780 <                        r = getTreeNode(h, k, root);
781 <                    } finally {
782 <                        releaseShared(0);
783 <                    }
784 <                    break;
785 <                }
786 <                else if ((e.hash & HASH_BITS) == h && k.equals(e.key)) {
787 <                    r = e;
788 <                    break;
789 <                }
790 <                else
791 <                    c = getState();
792 <            }
793 <            return r == null ? null : r.val;
624 >        public final boolean equals(Object o) {
625 >            Object k, v, u; Map.Entry<?,?> e;
626 >            return ((o instanceof Map.Entry) &&
627 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
628 >                    (v = e.getValue()) != null &&
629 >                    (k == key || k.equals(key)) &&
630 >                    (v == (u = val) || v.equals(u)));
631          }
632  
633          /**
634 <         * Finds or adds a node.
798 <         * @return null if added
634 >         * Virtualized support for map.get(); overridden in subclasses.
635           */
636 <        @SuppressWarnings("unchecked") // suppress Comparable cast warning
637 <        final TreeNode putTreeNode(int h, Object k, Object v) {
638 <            Class<?> c = k.getClass();
639 <            TreeNode pp = root, p = null;
640 <            int dir = 0;
641 <            while (pp != null) { // find existing node or leaf to insert at
642 <                int ph;  Object pk; Class<?> pc;
643 <                p = pp;
644 <                if ((ph = p.hash) == h) {
809 <                    if ((pk = p.key) == k || k.equals(pk))
810 <                        return p;
811 <                    if (c != (pc = pk.getClass()) ||
812 <                        !(k instanceof Comparable) ||
813 <                        (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
814 <                        dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName());
815 <                        TreeNode r = null, s = null, pl, pr;
816 <                        if (dir >= 0) {
817 <                            if ((pl = p.left) != null && h <= pl.hash)
818 <                                s = pl;
819 <                        }
820 <                        else if ((pr = p.right) != null && h >= pr.hash)
821 <                            s = pr;
822 <                        if (s != null && (r = getTreeNode(h, k, s)) != null)
823 <                            return r;
824 <                    }
825 <                }
826 <                else
827 <                    dir = (h < ph) ? -1 : 1;
828 <                pp = (dir > 0) ? p.right : p.left;
829 <            }
830 <
831 <            TreeNode f = first;
832 <            TreeNode x = first = new TreeNode(h, k, v, f, p);
833 <            if (p == null)
834 <                root = x;
835 <            else { // attach and rebalance; adapted from CLR
836 <                TreeNode xp, xpp;
837 <                if (f != null)
838 <                    f.prev = x;
839 <                if (dir <= 0)
840 <                    p.left = x;
841 <                else
842 <                    p.right = x;
843 <                x.red = true;
844 <                while (x != null && (xp = x.parent) != null && xp.red &&
845 <                       (xpp = xp.parent) != null) {
846 <                    TreeNode xppl = xpp.left;
847 <                    if (xp == xppl) {
848 <                        TreeNode y = xpp.right;
849 <                        if (y != null && y.red) {
850 <                            y.red = false;
851 <                            xp.red = false;
852 <                            xpp.red = true;
853 <                            x = xpp;
854 <                        }
855 <                        else {
856 <                            if (x == xp.right) {
857 <                                rotateLeft(x = xp);
858 <                                xpp = (xp = x.parent) == null ? null : xp.parent;
859 <                            }
860 <                            if (xp != null) {
861 <                                xp.red = false;
862 <                                if (xpp != null) {
863 <                                    xpp.red = true;
864 <                                    rotateRight(xpp);
865 <                                }
866 <                            }
867 <                        }
868 <                    }
869 <                    else {
870 <                        TreeNode y = xppl;
871 <                        if (y != null && y.red) {
872 <                            y.red = false;
873 <                            xp.red = false;
874 <                            xpp.red = true;
875 <                            x = xpp;
876 <                        }
877 <                        else {
878 <                            if (x == xp.left) {
879 <                                rotateRight(x = xp);
880 <                                xpp = (xp = x.parent) == null ? null : xp.parent;
881 <                            }
882 <                            if (xp != null) {
883 <                                xp.red = false;
884 <                                if (xpp != null) {
885 <                                    xpp.red = true;
886 <                                    rotateLeft(xpp);
887 <                                }
888 <                            }
889 <                        }
890 <                    }
891 <                }
892 <                TreeNode r = root;
893 <                if (r != null && r.red)
894 <                    r.red = false;
636 >        Node<K,V> find(int h, Object k) {
637 >            Node<K,V> e = this;
638 >            if (k != null) {
639 >                do {
640 >                    K ek;
641 >                    if (e.hash == h &&
642 >                        ((ek = e.key) == k || (ek != null && k.equals(ek))))
643 >                        return e;
644 >                } while ((e = e.next) != null);
645              }
646              return null;
647          }
898
899        /**
900         * Removes the given node, that must be present before this
901         * call.  This is messier than typical red-black deletion code
902         * because we cannot swap the contents of an interior node
903         * with a leaf successor that is pinned by "next" pointers
904         * that are accessible independently of lock. So instead we
905         * swap the tree linkages.
906         */
907        final void deleteTreeNode(TreeNode p) {
908            TreeNode next = (TreeNode)p.next; // unlink traversal pointers
909            TreeNode pred = p.prev;
910            if (pred == null)
911                first = next;
912            else
913                pred.next = next;
914            if (next != null)
915                next.prev = pred;
916            TreeNode replacement;
917            TreeNode pl = p.left;
918            TreeNode pr = p.right;
919            if (pl != null && pr != null) {
920                TreeNode s = pr, sl;
921                while ((sl = s.left) != null) // find successor
922                    s = sl;
923                boolean c = s.red; s.red = p.red; p.red = c; // swap colors
924                TreeNode sr = s.right;
925                TreeNode pp = p.parent;
926                if (s == pr) { // p was s's direct parent
927                    p.parent = s;
928                    s.right = p;
929                }
930                else {
931                    TreeNode sp = s.parent;
932                    if ((p.parent = sp) != null) {
933                        if (s == sp.left)
934                            sp.left = p;
935                        else
936                            sp.right = p;
937                    }
938                    if ((s.right = pr) != null)
939                        pr.parent = s;
940                }
941                p.left = null;
942                if ((p.right = sr) != null)
943                    sr.parent = p;
944                if ((s.left = pl) != null)
945                    pl.parent = s;
946                if ((s.parent = pp) == null)
947                    root = s;
948                else if (p == pp.left)
949                    pp.left = s;
950                else
951                    pp.right = s;
952                replacement = sr;
953            }
954            else
955                replacement = (pl != null) ? pl : pr;
956            TreeNode pp = p.parent;
957            if (replacement == null) {
958                if (pp == null) {
959                    root = null;
960                    return;
961                }
962                replacement = p;
963            }
964            else {
965                replacement.parent = pp;
966                if (pp == null)
967                    root = replacement;
968                else if (p == pp.left)
969                    pp.left = replacement;
970                else
971                    pp.right = replacement;
972                p.left = p.right = p.parent = null;
973            }
974            if (!p.red) { // rebalance, from CLR
975                TreeNode x = replacement;
976                while (x != null) {
977                    TreeNode xp, xpl;
978                    if (x.red || (xp = x.parent) == null) {
979                        x.red = false;
980                        break;
981                    }
982                    if (x == (xpl = xp.left)) {
983                        TreeNode sib = xp.right;
984                        if (sib != null && sib.red) {
985                            sib.red = false;
986                            xp.red = true;
987                            rotateLeft(xp);
988                            sib = (xp = x.parent) == null ? null : xp.right;
989                        }
990                        if (sib == null)
991                            x = xp;
992                        else {
993                            TreeNode sl = sib.left, sr = sib.right;
994                            if ((sr == null || !sr.red) &&
995                                (sl == null || !sl.red)) {
996                                sib.red = true;
997                                x = xp;
998                            }
999                            else {
1000                                if (sr == null || !sr.red) {
1001                                    if (sl != null)
1002                                        sl.red = false;
1003                                    sib.red = true;
1004                                    rotateRight(sib);
1005                                    sib = (xp = x.parent) == null ? null : xp.right;
1006                                }
1007                                if (sib != null) {
1008                                    sib.red = (xp == null) ? false : xp.red;
1009                                    if ((sr = sib.right) != null)
1010                                        sr.red = false;
1011                                }
1012                                if (xp != null) {
1013                                    xp.red = false;
1014                                    rotateLeft(xp);
1015                                }
1016                                x = root;
1017                            }
1018                        }
1019                    }
1020                    else { // symmetric
1021                        TreeNode sib = xpl;
1022                        if (sib != null && sib.red) {
1023                            sib.red = false;
1024                            xp.red = true;
1025                            rotateRight(xp);
1026                            sib = (xp = x.parent) == null ? null : xp.left;
1027                        }
1028                        if (sib == null)
1029                            x = xp;
1030                        else {
1031                            TreeNode sl = sib.left, sr = sib.right;
1032                            if ((sl == null || !sl.red) &&
1033                                (sr == null || !sr.red)) {
1034                                sib.red = true;
1035                                x = xp;
1036                            }
1037                            else {
1038                                if (sl == null || !sl.red) {
1039                                    if (sr != null)
1040                                        sr.red = false;
1041                                    sib.red = true;
1042                                    rotateLeft(sib);
1043                                    sib = (xp = x.parent) == null ? null : xp.left;
1044                                }
1045                                if (sib != null) {
1046                                    sib.red = (xp == null) ? false : xp.red;
1047                                    if ((sl = sib.left) != null)
1048                                        sl.red = false;
1049                                }
1050                                if (xp != null) {
1051                                    xp.red = false;
1052                                    rotateRight(xp);
1053                                }
1054                                x = root;
1055                            }
1056                        }
1057                    }
1058                }
1059            }
1060            if (p == replacement && (pp = p.parent) != null) {
1061                if (p == pp.left) // detach pointers
1062                    pp.left = null;
1063                else if (p == pp.right)
1064                    pp.right = null;
1065                p.parent = null;
1066            }
1067        }
648      }
649  
650 <    /* ---------------- Collision reduction methods -------------- */
650 >    /* ---------------- Static utilities -------------- */
651  
652      /**
653 <     * Spreads higher bits to lower, and also forces top 2 bits to 0.
654 <     * Because the table uses power-of-two masking, sets of hashes
655 <     * that vary only in bits above the current mask will always
656 <     * collide. (Among known examples are sets of Float keys holding
657 <     * consecutive whole numbers in small tables.)  To counter this,
658 <     * we apply a transform that spreads the impact of higher bits
653 >     * Spreads (XORs) higher bits of hash to lower and also forces top
654 >     * bit to 0. Because the table uses power-of-two masking, sets of
655 >     * hashes that vary only in bits above the current mask will
656 >     * always collide. (Among known examples are sets of Float keys
657 >     * holding consecutive whole numbers in small tables.)  So we
658 >     * apply a transform that spreads the impact of higher bits
659       * downward. There is a tradeoff between speed, utility, and
660       * quality of bit-spreading. Because many common sets of hashes
661 <     * are already reasonably distributed across bits (so don't benefit
662 <     * from spreading), and because we use trees to handle large sets
663 <     * of collisions in bins, we don't need excessively high quality.
661 >     * are already reasonably distributed (so don't benefit from
662 >     * spreading), and because we use trees to handle large sets of
663 >     * collisions in bins, we just XOR some shifted bits in the
664 >     * cheapest possible way to reduce systematic lossage, as well as
665 >     * to incorporate impact of the highest bits that would otherwise
666 >     * never be used in index calculations because of table bounds.
667       */
668 <    private static final int spread(int h) {
669 <        h ^= (h >>> 18) ^ (h >>> 12);
1087 <        return (h ^ (h >>> 10)) & HASH_BITS;
668 >    static final int spread(int h) {
669 >        return (h ^ (h >>> 16)) & HASH_BITS;
670      }
671  
672      /**
673 <     * Replaces a list bin with a tree bin. Call only when locked.
674 <     * Fails to replace if the given key is non-comparable or table
1093 <     * is, or needs, resizing.
673 >     * Returns a power of two table size for the given desired capacity.
674 >     * See Hackers Delight, sec 3.2
675       */
676 <    private final void replaceWithTreeBin(Node[] tab, int index, Object key) {
677 <        if ((key instanceof Comparable) &&
678 <            (tab.length >= MAXIMUM_CAPACITY || counter.sum() < (long)sizeCtl)) {
679 <            TreeBin t = new TreeBin();
680 <            for (Node e = tabAt(tab, index); e != null; e = e.next)
681 <                t.putTreeNode(e.hash & HASH_BITS, e.key, e.val);
682 <            setTabAt(tab, index, new Node(MOVED, t, null, null));
683 <        }
676 >    private static final int tableSizeFor(int c) {
677 >        int n = c - 1;
678 >        n |= n >>> 1;
679 >        n |= n >>> 2;
680 >        n |= n >>> 4;
681 >        n |= n >>> 8;
682 >        n |= n >>> 16;
683 >        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
684      }
685  
686 <    /* ---------------- Internal access and update methods -------------- */
687 <
688 <    /** Implementation for get and containsKey */
689 <    private final Object internalGet(Object k) {
690 <        int h = spread(k.hashCode());
691 <        retry: for (Node[] tab = table; tab != null;) {
692 <            Node e, p; Object ek, ev; int eh;      // locals to read fields once
693 <            for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) {
694 <                if ((eh = e.hash) == MOVED) {
695 <                    if ((ek = e.key) instanceof TreeBin)  // search TreeBin
696 <                        return ((TreeBin)ek).getValue(h, k);
697 <                    else {                        // restart with new table
698 <                        tab = (Node[])ek;
699 <                        continue retry;
700 <                    }
686 >    /**
687 >     * Returns x's Class if it is of the form "class C implements
688 >     * Comparable<C>", else null.
689 >     */
690 >    static Class<?> comparableClassFor(Object x) {
691 >        if (x instanceof Comparable) {
692 >            Class<?> c; Type[] ts, as; Type t; ParameterizedType p;
693 >            if ((c = x.getClass()) == String.class) // bypass checks
694 >                return c;
695 >            if ((ts = c.getGenericInterfaces()) != null) {
696 >                for (int i = 0; i < ts.length; ++i) {
697 >                    if (((t = ts[i]) instanceof ParameterizedType) &&
698 >                        ((p = (ParameterizedType)t).getRawType() ==
699 >                         Comparable.class) &&
700 >                        (as = p.getActualTypeArguments()) != null &&
701 >                        as.length == 1 && as[0] == c) // type arg is c
702 >                        return c;
703                  }
1121                else if ((eh & HASH_BITS) == h && (ev = e.val) != null &&
1122                         ((ek = e.key) == k || k.equals(ek)))
1123                    return ev;
704              }
1125            break;
705          }
706          return null;
707      }
708  
709      /**
710 <     * Implementation for the four public remove/replace methods:
711 <     * Replaces node value with v, conditional upon match of cv if
1133 <     * non-null.  If resulting value is null, delete.
710 >     * Returns k.compareTo(x) if x matches kc (k's screened comparable
711 >     * class), else 0.
712       */
713 <    private final Object internalReplace(Object k, Object v, Object cv) {
714 <        int h = spread(k.hashCode());
715 <        Object oldVal = null;
716 <        for (Node[] tab = table;;) {
1139 <            Node f; int i, fh; Object fk;
1140 <            if (tab == null ||
1141 <                (f = tabAt(tab, i = (tab.length - 1) & h)) == null)
1142 <                break;
1143 <            else if ((fh = f.hash) == MOVED) {
1144 <                if ((fk = f.key) instanceof TreeBin) {
1145 <                    TreeBin t = (TreeBin)fk;
1146 <                    boolean validated = false;
1147 <                    boolean deleted = false;
1148 <                    t.acquire(0);
1149 <                    try {
1150 <                        if (tabAt(tab, i) == f) {
1151 <                            validated = true;
1152 <                            TreeNode p = t.getTreeNode(h, k, t.root);
1153 <                            if (p != null) {
1154 <                                Object pv = p.val;
1155 <                                if (cv == null || cv == pv || cv.equals(pv)) {
1156 <                                    oldVal = pv;
1157 <                                    if ((p.val = v) == null) {
1158 <                                        deleted = true;
1159 <                                        t.deleteTreeNode(p);
1160 <                                    }
1161 <                                }
1162 <                            }
1163 <                        }
1164 <                    } finally {
1165 <                        t.release(0);
1166 <                    }
1167 <                    if (validated) {
1168 <                        if (deleted)
1169 <                            counter.add(-1L);
1170 <                        break;
1171 <                    }
1172 <                }
1173 <                else
1174 <                    tab = (Node[])fk;
1175 <            }
1176 <            else if ((fh & HASH_BITS) != h && f.next == null) // precheck
1177 <                break;                          // rules out possible existence
1178 <            else if ((fh & LOCKED) != 0) {
1179 <                checkForResize();               // try resizing if can't get lock
1180 <                f.tryAwaitLock(tab, i);
1181 <            }
1182 <            else if (f.casHash(fh, fh | LOCKED)) {
1183 <                boolean validated = false;
1184 <                boolean deleted = false;
1185 <                try {
1186 <                    if (tabAt(tab, i) == f) {
1187 <                        validated = true;
1188 <                        for (Node e = f, pred = null;;) {
1189 <                            Object ek, ev;
1190 <                            if ((e.hash & HASH_BITS) == h &&
1191 <                                ((ev = e.val) != null) &&
1192 <                                ((ek = e.key) == k || k.equals(ek))) {
1193 <                                if (cv == null || cv == ev || cv.equals(ev)) {
1194 <                                    oldVal = ev;
1195 <                                    if ((e.val = v) == null) {
1196 <                                        deleted = true;
1197 <                                        Node en = e.next;
1198 <                                        if (pred != null)
1199 <                                            pred.next = en;
1200 <                                        else
1201 <                                            setTabAt(tab, i, en);
1202 <                                    }
1203 <                                }
1204 <                                break;
1205 <                            }
1206 <                            pred = e;
1207 <                            if ((e = e.next) == null)
1208 <                                break;
1209 <                        }
1210 <                    }
1211 <                } finally {
1212 <                    if (!f.casHash(fh | LOCKED, fh)) {
1213 <                        f.hash = fh;
1214 <                        synchronized (f) { f.notifyAll(); };
1215 <                    }
1216 <                }
1217 <                if (validated) {
1218 <                    if (deleted)
1219 <                        counter.add(-1L);
1220 <                    break;
1221 <                }
1222 <            }
1223 <        }
1224 <        return oldVal;
713 >    @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
714 >    static int compareComparables(Class<?> kc, Object k, Object x) {
715 >        return (x == null || x.getClass() != kc ? 0 :
716 >                ((Comparable)k).compareTo(x));
717      }
718  
719 <    /*
1228 <     * Internal versions of the five insertion methods, each a
1229 <     * little more complicated than the last. All have
1230 <     * the same basic structure as the first (internalPut):
1231 <     *  1. If table uninitialized, create
1232 <     *  2. If bin empty, try to CAS new node
1233 <     *  3. If bin stale, use new table
1234 <     *  4. if bin converted to TreeBin, validate and relay to TreeBin methods
1235 <     *  5. Lock and validate; if valid, scan and add or update
1236 <     *
1237 <     * The others interweave other checks and/or alternative actions:
1238 <     *  * Plain put checks for and performs resize after insertion.
1239 <     *  * putIfAbsent prescans for mapping without lock (and fails to add
1240 <     *    if present), which also makes pre-emptive resize checks worthwhile.
1241 <     *  * computeIfAbsent extends form used in putIfAbsent with additional
1242 <     *    mechanics to deal with, calls, potential exceptions and null
1243 <     *    returns from function call.
1244 <     *  * compute uses the same function-call mechanics, but without
1245 <     *    the prescans
1246 <     *  * putAll attempts to pre-allocate enough table space
1247 <     *    and more lazily performs count updates and checks.
1248 <     *
1249 <     * Someday when details settle down a bit more, it might be worth
1250 <     * some factoring to reduce sprawl.
1251 <     */
1252 <
1253 <    /** Implementation for put */
1254 <    private final Object internalPut(Object k, Object v) {
1255 <        int h = spread(k.hashCode());
1256 <        int count = 0;
1257 <        for (Node[] tab = table;;) {
1258 <            int i; Node f; int fh; Object fk;
1259 <            if (tab == null)
1260 <                tab = initTable();
1261 <            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1262 <                if (casTabAt(tab, i, null, new Node(h, k, v, null)))
1263 <                    break;                   // no lock when adding to empty bin
1264 <            }
1265 <            else if ((fh = f.hash) == MOVED) {
1266 <                if ((fk = f.key) instanceof TreeBin) {
1267 <                    TreeBin t = (TreeBin)fk;
1268 <                    Object oldVal = null;
1269 <                    t.acquire(0);
1270 <                    try {
1271 <                        if (tabAt(tab, i) == f) {
1272 <                            count = 2;
1273 <                            TreeNode p = t.putTreeNode(h, k, v);
1274 <                            if (p != null) {
1275 <                                oldVal = p.val;
1276 <                                p.val = v;
1277 <                            }
1278 <                        }
1279 <                    } finally {
1280 <                        t.release(0);
1281 <                    }
1282 <                    if (count != 0) {
1283 <                        if (oldVal != null)
1284 <                            return oldVal;
1285 <                        break;
1286 <                    }
1287 <                }
1288 <                else
1289 <                    tab = (Node[])fk;
1290 <            }
1291 <            else if ((fh & LOCKED) != 0) {
1292 <                checkForResize();
1293 <                f.tryAwaitLock(tab, i);
1294 <            }
1295 <            else if (f.casHash(fh, fh | LOCKED)) {
1296 <                Object oldVal = null;
1297 <                try {                        // needed in case equals() throws
1298 <                    if (tabAt(tab, i) == f) {
1299 <                        count = 1;
1300 <                        for (Node e = f;; ++count) {
1301 <                            Object ek, ev;
1302 <                            if ((e.hash & HASH_BITS) == h &&
1303 <                                (ev = e.val) != null &&
1304 <                                ((ek = e.key) == k || k.equals(ek))) {
1305 <                                oldVal = ev;
1306 <                                e.val = v;
1307 <                                break;
1308 <                            }
1309 <                            Node last = e;
1310 <                            if ((e = e.next) == null) {
1311 <                                last.next = new Node(h, k, v, null);
1312 <                                if (count >= TREE_THRESHOLD)
1313 <                                    replaceWithTreeBin(tab, i, k);
1314 <                                break;
1315 <                            }
1316 <                        }
1317 <                    }
1318 <                } finally {                  // unlock and signal if needed
1319 <                    if (!f.casHash(fh | LOCKED, fh)) {
1320 <                        f.hash = fh;
1321 <                        synchronized (f) { f.notifyAll(); };
1322 <                    }
1323 <                }
1324 <                if (count != 0) {
1325 <                    if (oldVal != null)
1326 <                        return oldVal;
1327 <                    if (tab.length <= 64)
1328 <                        count = 2;
1329 <                    break;
1330 <                }
1331 <            }
1332 <        }
1333 <        counter.add(1L);
1334 <        if (count > 1)
1335 <            checkForResize();
1336 <        return null;
1337 <    }
719 >    /* ---------------- Table element access -------------- */
720  
721 <    /** Implementation for putIfAbsent */
722 <    private final Object internalPutIfAbsent(Object k, Object v) {
723 <        int h = spread(k.hashCode());
724 <        int count = 0;
725 <        for (Node[] tab = table;;) {
726 <            int i; Node f; int fh; Object fk, fv;
727 <            if (tab == null)
728 <                tab = initTable();
729 <            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
730 <                if (casTabAt(tab, i, null, new Node(h, k, v, null)))
731 <                    break;
732 <            }
733 <            else if ((fh = f.hash) == MOVED) {
734 <                if ((fk = f.key) instanceof TreeBin) {
735 <                    TreeBin t = (TreeBin)fk;
1354 <                    Object oldVal = null;
1355 <                    t.acquire(0);
1356 <                    try {
1357 <                        if (tabAt(tab, i) == f) {
1358 <                            count = 2;
1359 <                            TreeNode p = t.putTreeNode(h, k, v);
1360 <                            if (p != null)
1361 <                                oldVal = p.val;
1362 <                        }
1363 <                    } finally {
1364 <                        t.release(0);
1365 <                    }
1366 <                    if (count != 0) {
1367 <                        if (oldVal != null)
1368 <                            return oldVal;
1369 <                        break;
1370 <                    }
1371 <                }
1372 <                else
1373 <                    tab = (Node[])fk;
1374 <            }
1375 <            else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
1376 <                     ((fk = f.key) == k || k.equals(fk)))
1377 <                return fv;
1378 <            else {
1379 <                Node g = f.next;
1380 <                if (g != null) { // at least 2 nodes -- search and maybe resize
1381 <                    for (Node e = g;;) {
1382 <                        Object ek, ev;
1383 <                        if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
1384 <                            ((ek = e.key) == k || k.equals(ek)))
1385 <                            return ev;
1386 <                        if ((e = e.next) == null) {
1387 <                            checkForResize();
1388 <                            break;
1389 <                        }
1390 <                    }
1391 <                }
1392 <                if (((fh = f.hash) & LOCKED) != 0) {
1393 <                    checkForResize();
1394 <                    f.tryAwaitLock(tab, i);
1395 <                }
1396 <                else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1397 <                    Object oldVal = null;
1398 <                    try {
1399 <                        if (tabAt(tab, i) == f) {
1400 <                            count = 1;
1401 <                            for (Node e = f;; ++count) {
1402 <                                Object ek, ev;
1403 <                                if ((e.hash & HASH_BITS) == h &&
1404 <                                    (ev = e.val) != null &&
1405 <                                    ((ek = e.key) == k || k.equals(ek))) {
1406 <                                    oldVal = ev;
1407 <                                    break;
1408 <                                }
1409 <                                Node last = e;
1410 <                                if ((e = e.next) == null) {
1411 <                                    last.next = new Node(h, k, v, null);
1412 <                                    if (count >= TREE_THRESHOLD)
1413 <                                        replaceWithTreeBin(tab, i, k);
1414 <                                    break;
1415 <                                }
1416 <                            }
1417 <                        }
1418 <                    } finally {
1419 <                        if (!f.casHash(fh | LOCKED, fh)) {
1420 <                            f.hash = fh;
1421 <                            synchronized (f) { f.notifyAll(); };
1422 <                        }
1423 <                    }
1424 <                    if (count != 0) {
1425 <                        if (oldVal != null)
1426 <                            return oldVal;
1427 <                        if (tab.length <= 64)
1428 <                            count = 2;
1429 <                        break;
1430 <                    }
1431 <                }
1432 <            }
1433 <        }
1434 <        counter.add(1L);
1435 <        if (count > 1)
1436 <            checkForResize();
1437 <        return null;
1438 <    }
721 >    /*
722 >     * Volatile access methods are used for table elements as well as
723 >     * elements of in-progress next table while resizing.  All uses of
724 >     * the tab arguments must be null checked by callers.  All callers
725 >     * also paranoically precheck that tab's length is not zero (or an
726 >     * equivalent check), thus ensuring that any index argument taking
727 >     * the form of a hash value anded with (length - 1) is a valid
728 >     * index.  Note that, to be correct wrt arbitrary concurrency
729 >     * errors by users, these checks must operate on local variables,
730 >     * which accounts for some odd-looking inline assignments below.
731 >     * Note that calls to setTabAt always occur within locked regions,
732 >     * and so in principle require only release ordering, not need
733 >     * full volatile semantics, but are currently coded as volatile
734 >     * writes to be conservative.
735 >     */
736  
737 <    /** Implementation for computeIfAbsent */
738 <    private final Object internalComputeIfAbsent(K k,
739 <                                                 MappingFunction<? super K, ?> mf) {
1443 <        int h = spread(k.hashCode());
1444 <        Object val = null;
1445 <        int count = 0;
1446 <        for (Node[] tab = table;;) {
1447 <            Node f; int i, fh; Object fk, fv;
1448 <            if (tab == null)
1449 <                tab = initTable();
1450 <            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1451 <                Node node = new Node(fh = h | LOCKED, k, null, null);
1452 <                if (casTabAt(tab, i, null, node)) {
1453 <                    count = 1;
1454 <                    try {
1455 <                        if ((val = mf.map(k)) != null)
1456 <                            node.val = val;
1457 <                    } finally {
1458 <                        if (val == null)
1459 <                            setTabAt(tab, i, null);
1460 <                        if (!node.casHash(fh, h)) {
1461 <                            node.hash = h;
1462 <                            synchronized (node) { node.notifyAll(); };
1463 <                        }
1464 <                    }
1465 <                }
1466 <                if (count != 0)
1467 <                    break;
1468 <            }
1469 <            else if ((fh = f.hash) == MOVED) {
1470 <                if ((fk = f.key) instanceof TreeBin) {
1471 <                    TreeBin t = (TreeBin)fk;
1472 <                    boolean added = false;
1473 <                    t.acquire(0);
1474 <                    try {
1475 <                        if (tabAt(tab, i) == f) {
1476 <                            count = 1;
1477 <                            TreeNode p = t.getTreeNode(h, k, t.root);
1478 <                            if (p != null)
1479 <                                val = p.val;
1480 <                            else if ((val = mf.map(k)) != null) {
1481 <                                added = true;
1482 <                                count = 2;
1483 <                                t.putTreeNode(h, k, val);
1484 <                            }
1485 <                        }
1486 <                    } finally {
1487 <                        t.release(0);
1488 <                    }
1489 <                    if (count != 0) {
1490 <                        if (!added)
1491 <                            return val;
1492 <                        break;
1493 <                    }
1494 <                }
1495 <                else
1496 <                    tab = (Node[])fk;
1497 <            }
1498 <            else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
1499 <                     ((fk = f.key) == k || k.equals(fk)))
1500 <                return fv;
1501 <            else {
1502 <                Node g = f.next;
1503 <                if (g != null) {
1504 <                    for (Node e = g;;) {
1505 <                        Object ek, ev;
1506 <                        if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
1507 <                            ((ek = e.key) == k || k.equals(ek)))
1508 <                            return ev;
1509 <                        if ((e = e.next) == null) {
1510 <                            checkForResize();
1511 <                            break;
1512 <                        }
1513 <                    }
1514 <                }
1515 <                if (((fh = f.hash) & LOCKED) != 0) {
1516 <                    checkForResize();
1517 <                    f.tryAwaitLock(tab, i);
1518 <                }
1519 <                else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1520 <                    boolean added = false;
1521 <                    try {
1522 <                        if (tabAt(tab, i) == f) {
1523 <                            count = 1;
1524 <                            for (Node e = f;; ++count) {
1525 <                                Object ek, ev;
1526 <                                if ((e.hash & HASH_BITS) == h &&
1527 <                                    (ev = e.val) != null &&
1528 <                                    ((ek = e.key) == k || k.equals(ek))) {
1529 <                                    val = ev;
1530 <                                    break;
1531 <                                }
1532 <                                Node last = e;
1533 <                                if ((e = e.next) == null) {
1534 <                                    if ((val = mf.map(k)) != null) {
1535 <                                        added = true;
1536 <                                        last.next = new Node(h, k, val, null);
1537 <                                        if (count >= TREE_THRESHOLD)
1538 <                                            replaceWithTreeBin(tab, i, k);
1539 <                                    }
1540 <                                    break;
1541 <                                }
1542 <                            }
1543 <                        }
1544 <                    } finally {
1545 <                        if (!f.casHash(fh | LOCKED, fh)) {
1546 <                            f.hash = fh;
1547 <                            synchronized (f) { f.notifyAll(); };
1548 <                        }
1549 <                    }
1550 <                    if (count != 0) {
1551 <                        if (!added)
1552 <                            return val;
1553 <                        if (tab.length <= 64)
1554 <                            count = 2;
1555 <                        break;
1556 <                    }
1557 <                }
1558 <            }
1559 <        }
1560 <        if (val != null) {
1561 <            counter.add(1L);
1562 <            if (count > 1)
1563 <                checkForResize();
1564 <        }
1565 <        return val;
737 >    @SuppressWarnings("unchecked")
738 >    static final <K,V> Node<K,V> tabAt(Node<K,V>[] tab, int i) {
739 >        return (Node<K,V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
740      }
741  
742 <    /** Implementation for compute */
743 <    @SuppressWarnings("unchecked")
744 <    private final Object internalCompute(K k,
1571 <                                         RemappingFunction<? super K, V> mf) {
1572 <        int h = spread(k.hashCode());
1573 <        Object val = null;
1574 <        int delta = 0;
1575 <        int count = 0;
1576 <        for (Node[] tab = table;;) {
1577 <            Node f; int i, fh; Object fk;
1578 <            if (tab == null)
1579 <                tab = initTable();
1580 <            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1581 <                Node node = new Node(fh = h | LOCKED, k, null, null);
1582 <                if (casTabAt(tab, i, null, node)) {
1583 <                    try {
1584 <                        count = 1;
1585 <                        if ((val = mf.remap(k, null)) != null) {
1586 <                            node.val = val;
1587 <                            delta = 1;
1588 <                        }
1589 <                    } finally {
1590 <                        if (delta == 0)
1591 <                            setTabAt(tab, i, null);
1592 <                        if (!node.casHash(fh, h)) {
1593 <                            node.hash = h;
1594 <                            synchronized (node) { node.notifyAll(); };
1595 <                        }
1596 <                    }
1597 <                }
1598 <                if (count != 0)
1599 <                    break;
1600 <            }
1601 <            else if ((fh = f.hash) == MOVED) {
1602 <                if ((fk = f.key) instanceof TreeBin) {
1603 <                    TreeBin t = (TreeBin)fk;
1604 <                    t.acquire(0);
1605 <                    try {
1606 <                        if (tabAt(tab, i) == f) {
1607 <                            count = 1;
1608 <                            TreeNode p = t.getTreeNode(h, k, t.root);
1609 <                            Object pv = (p == null) ? null : p.val;
1610 <                            if ((val = mf.remap(k, (V)pv)) != null) {
1611 <                                if (p != null)
1612 <                                    p.val = val;
1613 <                                else {
1614 <                                    count = 2;
1615 <                                    delta = 1;
1616 <                                    t.putTreeNode(h, k, val);
1617 <                                }
1618 <                            }
1619 <                            else if (p != null) {
1620 <                                delta = -1;
1621 <                                t.deleteTreeNode(p);
1622 <                            }
1623 <                        }
1624 <                    } finally {
1625 <                        t.release(0);
1626 <                    }
1627 <                    if (count != 0)
1628 <                        break;
1629 <                }
1630 <                else
1631 <                    tab = (Node[])fk;
1632 <            }
1633 <            else if ((fh & LOCKED) != 0) {
1634 <                checkForResize();
1635 <                f.tryAwaitLock(tab, i);
1636 <            }
1637 <            else if (f.casHash(fh, fh | LOCKED)) {
1638 <                try {
1639 <                    if (tabAt(tab, i) == f) {
1640 <                        count = 1;
1641 <                        for (Node e = f, pred = null;; ++count) {
1642 <                            Object ek, ev;
1643 <                            if ((e.hash & HASH_BITS) == h &&
1644 <                                (ev = e.val) != null &&
1645 <                                ((ek = e.key) == k || k.equals(ek))) {
1646 <                                val = mf.remap(k, (V)ev);
1647 <                                if (val != null)
1648 <                                    e.val = val;
1649 <                                else {
1650 <                                    delta = -1;
1651 <                                    Node en = e.next;
1652 <                                    if (pred != null)
1653 <                                        pred.next = en;
1654 <                                    else
1655 <                                        setTabAt(tab, i, en);
1656 <                                }
1657 <                                break;
1658 <                            }
1659 <                            pred = e;
1660 <                            if ((e = e.next) == null) {
1661 <                                if ((val = mf.remap(k, null)) != null) {
1662 <                                    pred.next = new Node(h, k, val, null);
1663 <                                    delta = 1;
1664 <                                    if (count >= TREE_THRESHOLD)
1665 <                                        replaceWithTreeBin(tab, i, k);
1666 <                                }
1667 <                                break;
1668 <                            }
1669 <                        }
1670 <                    }
1671 <                } finally {
1672 <                    if (!f.casHash(fh | LOCKED, fh)) {
1673 <                        f.hash = fh;
1674 <                        synchronized (f) { f.notifyAll(); };
1675 <                    }
1676 <                }
1677 <                if (count != 0) {
1678 <                    if (tab.length <= 64)
1679 <                        count = 2;
1680 <                    break;
1681 <                }
1682 <            }
1683 <        }
1684 <        if (delta != 0) {
1685 <            counter.add((long)delta);
1686 <            if (count > 1)
1687 <                checkForResize();
1688 <        }
1689 <        return val;
742 >    static final <K,V> boolean casTabAt(Node<K,V>[] tab, int i,
743 >                                        Node<K,V> c, Node<K,V> v) {
744 >        return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
745      }
746  
747 <    /** Implementation for putAll */
748 <    private final void internalPutAll(Map<?, ?> m) {
1694 <        tryPresize(m.size());
1695 <        long delta = 0L;     // number of uncommitted additions
1696 <        boolean npe = false; // to throw exception on exit for nulls
1697 <        try {                // to clean up counts on other exceptions
1698 <            for (Map.Entry<?, ?> entry : m.entrySet()) {
1699 <                Object k, v;
1700 <                if (entry == null || (k = entry.getKey()) == null ||
1701 <                    (v = entry.getValue()) == null) {
1702 <                    npe = true;
1703 <                    break;
1704 <                }
1705 <                int h = spread(k.hashCode());
1706 <                for (Node[] tab = table;;) {
1707 <                    int i; Node f; int fh; Object fk;
1708 <                    if (tab == null)
1709 <                        tab = initTable();
1710 <                    else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
1711 <                        if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
1712 <                            ++delta;
1713 <                            break;
1714 <                        }
1715 <                    }
1716 <                    else if ((fh = f.hash) == MOVED) {
1717 <                        if ((fk = f.key) instanceof TreeBin) {
1718 <                            TreeBin t = (TreeBin)fk;
1719 <                            boolean validated = false;
1720 <                            t.acquire(0);
1721 <                            try {
1722 <                                if (tabAt(tab, i) == f) {
1723 <                                    validated = true;
1724 <                                    TreeNode p = t.getTreeNode(h, k, t.root);
1725 <                                    if (p != null)
1726 <                                        p.val = v;
1727 <                                    else {
1728 <                                        t.putTreeNode(h, k, v);
1729 <                                        ++delta;
1730 <                                    }
1731 <                                }
1732 <                            } finally {
1733 <                                t.release(0);
1734 <                            }
1735 <                            if (validated)
1736 <                                break;
1737 <                        }
1738 <                        else
1739 <                            tab = (Node[])fk;
1740 <                    }
1741 <                    else if ((fh & LOCKED) != 0) {
1742 <                        counter.add(delta);
1743 <                        delta = 0L;
1744 <                        checkForResize();
1745 <                        f.tryAwaitLock(tab, i);
1746 <                    }
1747 <                    else if (f.casHash(fh, fh | LOCKED)) {
1748 <                        int count = 0;
1749 <                        try {
1750 <                            if (tabAt(tab, i) == f) {
1751 <                                count = 1;
1752 <                                for (Node e = f;; ++count) {
1753 <                                    Object ek, ev;
1754 <                                    if ((e.hash & HASH_BITS) == h &&
1755 <                                        (ev = e.val) != null &&
1756 <                                        ((ek = e.key) == k || k.equals(ek))) {
1757 <                                        e.val = v;
1758 <                                        break;
1759 <                                    }
1760 <                                    Node last = e;
1761 <                                    if ((e = e.next) == null) {
1762 <                                        ++delta;
1763 <                                        last.next = new Node(h, k, v, null);
1764 <                                        if (count >= TREE_THRESHOLD)
1765 <                                            replaceWithTreeBin(tab, i, k);
1766 <                                        break;
1767 <                                    }
1768 <                                }
1769 <                            }
1770 <                        } finally {
1771 <                            if (!f.casHash(fh | LOCKED, fh)) {
1772 <                                f.hash = fh;
1773 <                                synchronized (f) { f.notifyAll(); };
1774 <                            }
1775 <                        }
1776 <                        if (count != 0) {
1777 <                            if (count > 1) {
1778 <                                counter.add(delta);
1779 <                                delta = 0L;
1780 <                                checkForResize();
1781 <                            }
1782 <                            break;
1783 <                        }
1784 <                    }
1785 <                }
1786 <            }
1787 <        } finally {
1788 <            if (delta != 0)
1789 <                counter.add(delta);
1790 <        }
1791 <        if (npe)
1792 <            throw new NullPointerException();
747 >    static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {
748 >        U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
749      }
750  
751 <    /* ---------------- Table Initialization and Resizing -------------- */
751 >    /* ---------------- Fields -------------- */
752  
753      /**
754 <     * Returns a power of two table size for the given desired capacity.
755 <     * See Hackers Delight, sec 3.2
754 >     * The array of bins. Lazily initialized upon first insertion.
755 >     * Size is always a power of two. Accessed directly by iterators.
756       */
757 <    private static final int tableSizeFor(int c) {
1802 <        int n = c - 1;
1803 <        n |= n >>> 1;
1804 <        n |= n >>> 2;
1805 <        n |= n >>> 4;
1806 <        n |= n >>> 8;
1807 <        n |= n >>> 16;
1808 <        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
1809 <    }
757 >    transient volatile Node<K,V>[] table;
758  
759      /**
760 <     * Initializes table, using the size recorded in sizeCtl.
760 >     * The next table to use; non-null only while resizing.
761       */
762 <    private final Node[] initTable() {
1815 <        Node[] tab; int sc;
1816 <        while ((tab = table) == null) {
1817 <            if ((sc = sizeCtl) < 0)
1818 <                Thread.yield(); // lost initialization race; just spin
1819 <            else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1820 <                try {
1821 <                    if ((tab = table) == null) {
1822 <                        int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
1823 <                        tab = table = new Node[n];
1824 <                        sc = n - (n >>> 2);
1825 <                    }
1826 <                } finally {
1827 <                    sizeCtl = sc;
1828 <                }
1829 <                break;
1830 <            }
1831 <        }
1832 <        return tab;
1833 <    }
762 >    private transient volatile Node<K,V>[] nextTable;
763  
764      /**
765 <     * If table is too small and not already resizing, creates next
766 <     * table and transfers bins.  Rechecks occupancy after a transfer
767 <     * to see if another resize is already needed because resizings
1839 <     * are lagging additions.
1840 <     */
1841 <    private final void checkForResize() {
1842 <        Node[] tab; int n, sc;
1843 <        while ((tab = table) != null &&
1844 <               (n = tab.length) < MAXIMUM_CAPACITY &&
1845 <               (sc = sizeCtl) >= 0 && counter.sum() >= (long)sc &&
1846 <               UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1847 <            try {
1848 <                if (tab == table) {
1849 <                    table = rebuild(tab);
1850 <                    sc = (n << 1) - (n >>> 1);
1851 <                }
1852 <            } finally {
1853 <                sizeCtl = sc;
1854 <            }
1855 <        }
1856 <    }
1857 <
1858 <    /**
1859 <     * Tries to presize table to accommodate the given number of elements.
1860 <     *
1861 <     * @param size number of elements (doesn't need to be perfectly accurate)
765 >     * Base counter value, used mainly when there is no contention,
766 >     * but also as a fallback during table initialization
767 >     * races. Updated via CAS.
768       */
769 <    private final void tryPresize(int size) {
1864 <        int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1865 <            tableSizeFor(size + (size >>> 1) + 1);
1866 <        int sc;
1867 <        while ((sc = sizeCtl) >= 0) {
1868 <            Node[] tab = table; int n;
1869 <            if (tab == null || (n = tab.length) == 0) {
1870 <                n = (sc > c) ? sc : c;
1871 <                if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1872 <                    try {
1873 <                        if (table == tab) {
1874 <                            table = new Node[n];
1875 <                            sc = n - (n >>> 2);
1876 <                        }
1877 <                    } finally {
1878 <                        sizeCtl = sc;
1879 <                    }
1880 <                }
1881 <            }
1882 <            else if (c <= sc || n >= MAXIMUM_CAPACITY)
1883 <                break;
1884 <            else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1885 <                try {
1886 <                    if (table == tab) {
1887 <                        table = rebuild(tab);
1888 <                        sc = (n << 1) - (n >>> 1);
1889 <                    }
1890 <                } finally {
1891 <                    sizeCtl = sc;
1892 <                }
1893 <            }
1894 <        }
1895 <    }
769 >    private transient volatile long baseCount;
770  
771 <    /*
772 <     * Moves and/or copies the nodes in each bin to new table. See
773 <     * above for explanation.
774 <     *
775 <     * @return the new table
771 >    /**
772 >     * Table initialization and resizing control.  When negative, the
773 >     * table is being initialized or resized: -1 for initialization,
774 >     * else -(1 + the number of active resizing threads).  Otherwise,
775 >     * when table is null, holds the initial table size to use upon
776 >     * creation, or 0 for default. After initialization, holds the
777 >     * next element count value upon which to resize the table.
778       */
779 <    private static final Node[] rebuild(Node[] tab) {
1904 <        int n = tab.length;
1905 <        Node[] nextTab = new Node[n << 1];
1906 <        Node fwd = new Node(MOVED, nextTab, null, null);
1907 <        int[] buffer = null;       // holds bins to revisit; null until needed
1908 <        Node rev = null;           // reverse forwarder; null until needed
1909 <        int nbuffered = 0;         // the number of bins in buffer list
1910 <        int bufferIndex = 0;       // buffer index of current buffered bin
1911 <        int bin = n - 1;           // current non-buffered bin or -1 if none
1912 <
1913 <        for (int i = bin;;) {      // start upwards sweep
1914 <            int fh; Node f;
1915 <            if ((f = tabAt(tab, i)) == null) {
1916 <                if (bin >= 0) {    // no lock needed (or available)
1917 <                    if (!casTabAt(tab, i, f, fwd))
1918 <                        continue;
1919 <                }
1920 <                else {             // transiently use a locked forwarding node
1921 <                    Node g = new Node(MOVED|LOCKED, nextTab, null, null);
1922 <                    if (!casTabAt(tab, i, f, g))
1923 <                        continue;
1924 <                    setTabAt(nextTab, i, null);
1925 <                    setTabAt(nextTab, i + n, null);
1926 <                    setTabAt(tab, i, fwd);
1927 <                    if (!g.casHash(MOVED|LOCKED, MOVED)) {
1928 <                        g.hash = MOVED;
1929 <                        synchronized (g) { g.notifyAll(); }
1930 <                    }
1931 <                }
1932 <            }
1933 <            else if ((fh = f.hash) == MOVED) {
1934 <                Object fk = f.key;
1935 <                if (fk instanceof TreeBin) {
1936 <                    TreeBin t = (TreeBin)fk;
1937 <                    boolean validated = false;
1938 <                    t.acquire(0);
1939 <                    try {
1940 <                        if (tabAt(tab, i) == f) {
1941 <                            validated = true;
1942 <                            splitTreeBin(nextTab, i, t);
1943 <                            setTabAt(tab, i, fwd);
1944 <                        }
1945 <                    } finally {
1946 <                        t.release(0);
1947 <                    }
1948 <                    if (!validated)
1949 <                        continue;
1950 <                }
1951 <            }
1952 <            else if ((fh & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) {
1953 <                boolean validated = false;
1954 <                try {              // split to lo and hi lists; copying as needed
1955 <                    if (tabAt(tab, i) == f) {
1956 <                        validated = true;
1957 <                        splitBin(nextTab, i, f);
1958 <                        setTabAt(tab, i, fwd);
1959 <                    }
1960 <                } finally {
1961 <                    if (!f.casHash(fh | LOCKED, fh)) {
1962 <                        f.hash = fh;
1963 <                        synchronized (f) { f.notifyAll(); };
1964 <                    }
1965 <                }
1966 <                if (!validated)
1967 <                    continue;
1968 <            }
1969 <            else {
1970 <                if (buffer == null) // initialize buffer for revisits
1971 <                    buffer = new int[TRANSFER_BUFFER_SIZE];
1972 <                if (bin < 0 && bufferIndex > 0) {
1973 <                    int j = buffer[--bufferIndex];
1974 <                    buffer[bufferIndex] = i;
1975 <                    i = j;         // swap with another bin
1976 <                    continue;
1977 <                }
1978 <                if (bin < 0 || nbuffered >= TRANSFER_BUFFER_SIZE) {
1979 <                    f.tryAwaitLock(tab, i);
1980 <                    continue;      // no other options -- block
1981 <                }
1982 <                if (rev == null)   // initialize reverse-forwarder
1983 <                    rev = new Node(MOVED, tab, null, null);
1984 <                if (tabAt(tab, i) != f || (f.hash & LOCKED) == 0)
1985 <                    continue;      // recheck before adding to list
1986 <                buffer[nbuffered++] = i;
1987 <                setTabAt(nextTab, i, rev);     // install place-holders
1988 <                setTabAt(nextTab, i + n, rev);
1989 <            }
1990 <
1991 <            if (bin > 0)
1992 <                i = --bin;
1993 <            else if (buffer != null && nbuffered > 0) {
1994 <                bin = -1;
1995 <                i = buffer[bufferIndex = --nbuffered];
1996 <            }
1997 <            else
1998 <                return nextTab;
1999 <        }
2000 <    }
779 >    private transient volatile int sizeCtl;
780  
781      /**
782 <     * Splits a normal bin with list headed by e into lo and hi parts;
2004 <     * installs in given table.
782 >     * The next table index (plus one) to split while resizing.
783       */
784 <    private static void splitBin(Node[] nextTab, int i, Node e) {
2007 <        int bit = nextTab.length >>> 1; // bit to split on
2008 <        int runBit = e.hash & bit;
2009 <        Node lastRun = e, lo = null, hi = null;
2010 <        for (Node p = e.next; p != null; p = p.next) {
2011 <            int b = p.hash & bit;
2012 <            if (b != runBit) {
2013 <                runBit = b;
2014 <                lastRun = p;
2015 <            }
2016 <        }
2017 <        if (runBit == 0)
2018 <            lo = lastRun;
2019 <        else
2020 <            hi = lastRun;
2021 <        for (Node p = e; p != lastRun; p = p.next) {
2022 <            int ph = p.hash & HASH_BITS;
2023 <            Object pk = p.key, pv = p.val;
2024 <            if ((ph & bit) == 0)
2025 <                lo = new Node(ph, pk, pv, lo);
2026 <            else
2027 <                hi = new Node(ph, pk, pv, hi);
2028 <        }
2029 <        setTabAt(nextTab, i, lo);
2030 <        setTabAt(nextTab, i + bit, hi);
2031 <    }
784 >    private transient volatile int transferIndex;
785  
786      /**
787 <     * Splits a tree bin into lo and hi parts; installs in given table.
787 >     * The least available table index to split while resizing.
788       */
789 <    private static void splitTreeBin(Node[] nextTab, int i, TreeBin t) {
2037 <        int bit = nextTab.length >>> 1;
2038 <        TreeBin lt = new TreeBin();
2039 <        TreeBin ht = new TreeBin();
2040 <        int lc = 0, hc = 0;
2041 <        for (Node e = t.first; e != null; e = e.next) {
2042 <            int h = e.hash & HASH_BITS;
2043 <            Object k = e.key, v = e.val;
2044 <            if ((h & bit) == 0) {
2045 <                ++lc;
2046 <                lt.putTreeNode(h, k, v);
2047 <            }
2048 <            else {
2049 <                ++hc;
2050 <                ht.putTreeNode(h, k, v);
2051 <            }
2052 <        }
2053 <        Node ln, hn; // throw away trees if too small
2054 <        if (lc <= (TREE_THRESHOLD >>> 1)) {
2055 <            ln = null;
2056 <            for (Node p = lt.first; p != null; p = p.next)
2057 <                ln = new Node(p.hash, p.key, p.val, ln);
2058 <        }
2059 <        else
2060 <            ln = new Node(MOVED, lt, null, null);
2061 <        setTabAt(nextTab, i, ln);
2062 <        if (hc <= (TREE_THRESHOLD >>> 1)) {
2063 <            hn = null;
2064 <            for (Node p = ht.first; p != null; p = p.next)
2065 <                hn = new Node(p.hash, p.key, p.val, hn);
2066 <        }
2067 <        else
2068 <            hn = new Node(MOVED, ht, null, null);
2069 <        setTabAt(nextTab, i + bit, hn);
2070 <    }
789 >    private transient volatile int transferOrigin;
790  
791      /**
792 <     * Implementation for clear. Steps through each bin, removing all
2074 <     * nodes.
792 >     * Spinlock (locked via CAS) used when resizing and/or creating CounterCells.
793       */
794 <    private final void internalClear() {
2077 <        long delta = 0L; // negative number of deletions
2078 <        int i = 0;
2079 <        Node[] tab = table;
2080 <        while (tab != null && i < tab.length) {
2081 <            int fh; Object fk;
2082 <            Node f = tabAt(tab, i);
2083 <            if (f == null)
2084 <                ++i;
2085 <            else if ((fh = f.hash) == MOVED) {
2086 <                if ((fk = f.key) instanceof TreeBin) {
2087 <                    TreeBin t = (TreeBin)fk;
2088 <                    t.acquire(0);
2089 <                    try {
2090 <                        if (tabAt(tab, i) == f) {
2091 <                            for (Node p = t.first; p != null; p = p.next) {
2092 <                                p.val = null;
2093 <                                --delta;
2094 <                            }
2095 <                            t.first = null;
2096 <                            t.root = null;
2097 <                            ++i;
2098 <                        }
2099 <                    } finally {
2100 <                        t.release(0);
2101 <                    }
2102 <                }
2103 <                else
2104 <                    tab = (Node[])fk;
2105 <            }
2106 <            else if ((fh & LOCKED) != 0) {
2107 <                counter.add(delta); // opportunistically update count
2108 <                delta = 0L;
2109 <                f.tryAwaitLock(tab, i);
2110 <            }
2111 <            else if (f.casHash(fh, fh | LOCKED)) {
2112 <                try {
2113 <                    if (tabAt(tab, i) == f) {
2114 <                        for (Node e = f; e != null; e = e.next) {
2115 <                            e.val = null;
2116 <                            --delta;
2117 <                        }
2118 <                        setTabAt(tab, i, null);
2119 <                        ++i;
2120 <                    }
2121 <                } finally {
2122 <                    if (!f.casHash(fh | LOCKED, fh)) {
2123 <                        f.hash = fh;
2124 <                        synchronized (f) { f.notifyAll(); };
2125 <                    }
2126 <                }
2127 <            }
2128 <        }
2129 <        if (delta != 0)
2130 <            counter.add(delta);
2131 <    }
2132 <
2133 <    /* ----------------Table Traversal -------------- */
794 >    private transient volatile int cellsBusy;
795  
796      /**
797 <     * Encapsulates traversal for methods such as containsValue; also
2137 <     * serves as a base class for other iterators.
2138 <     *
2139 <     * At each step, the iterator snapshots the key ("nextKey") and
2140 <     * value ("nextVal") of a valid node (i.e., one that, at point of
2141 <     * snapshot, has a non-null user value). Because val fields can
2142 <     * change (including to null, indicating deletion), field nextVal
2143 <     * might not be accurate at point of use, but still maintains the
2144 <     * weak consistency property of holding a value that was once
2145 <     * valid.
2146 <     *
2147 <     * Internal traversals directly access these fields, as in:
2148 <     * {@code while (it.advance() != null) { process(it.nextKey); }}
2149 <     *
2150 <     * Exported iterators must track whether the iterator has advanced
2151 <     * (in hasNext vs next) (by setting/checking/nulling field
2152 <     * nextVal), and then extract key, value, or key-value pairs as
2153 <     * return values of next().
2154 <     *
2155 <     * The iterator visits once each still-valid node that was
2156 <     * reachable upon iterator construction. It might miss some that
2157 <     * were added to a bin after the bin was visited, which is OK wrt
2158 <     * consistency guarantees. Maintaining this property in the face
2159 <     * of possible ongoing resizes requires a fair amount of
2160 <     * bookkeeping state that is difficult to optimize away amidst
2161 <     * volatile accesses.  Even so, traversal maintains reasonable
2162 <     * throughput.
2163 <     *
2164 <     * Normally, iteration proceeds bin-by-bin traversing lists.
2165 <     * However, if the table has been resized, then all future steps
2166 <     * must traverse both the bin at the current index as well as at
2167 <     * (index + baseSize); and so on for further resizings. To
2168 <     * paranoically cope with potential sharing by users of iterators
2169 <     * across threads, iteration terminates if a bounds checks fails
2170 <     * for a table read.
797 >     * Table of counter cells. When non-null, size is a power of 2.
798       */
799 <    static class InternalIterator<K,V> {
2173 <        final ConcurrentHashMapV8<K, V> map;
2174 <        Node next;           // the next entry to use
2175 <        Node last;           // the last entry used
2176 <        Object nextKey;      // cached key field of next
2177 <        Object nextVal;      // cached val field of next
2178 <        Node[] tab;          // current table; updated if resized
2179 <        int index;           // index of bin to use next
2180 <        int baseIndex;       // current index of initial table
2181 <        int baseLimit;       // index bound for initial table
2182 <        final int baseSize;  // initial table size
2183 <
2184 <        /** Creates iterator for all entries in the table. */
2185 <        InternalIterator(ConcurrentHashMapV8<K, V> map) {
2186 <            this.tab = (this.map = map).table;
2187 <            baseLimit = baseSize = (tab == null) ? 0 : tab.length;
2188 <        }
2189 <
2190 <        /** Creates iterator for clone() and split() methods. */
2191 <        InternalIterator(InternalIterator<K,V> it, boolean split) {
2192 <            this.map = it.map;
2193 <            this.tab = it.tab;
2194 <            this.baseSize = it.baseSize;
2195 <            int lo = it.baseIndex;
2196 <            int hi = this.baseLimit = it.baseLimit;
2197 <            this.index = this.baseIndex =
2198 <                (split) ? (it.baseLimit = (lo + hi + 1) >>> 1) : lo;
2199 <        }
2200 <
2201 <        /**
2202 <         * Advances next; returns nextVal or null if terminated.
2203 <         * See above for explanation.
2204 <         */
2205 <        final Object advance() {
2206 <            Node e = last = next;
2207 <            Object ev = null;
2208 <            outer: do {
2209 <                if (e != null)                  // advance past used/skipped node
2210 <                    e = e.next;
2211 <                while (e == null) {             // get to next non-null bin
2212 <                    Node[] t; int b, i, n; Object ek; // checks must use locals
2213 <                    if ((b = baseIndex) >= baseLimit || (i = index) < 0 ||
2214 <                        (t = tab) == null || i >= (n = t.length))
2215 <                        break outer;
2216 <                    else if ((e = tabAt(t, i)) != null && e.hash == MOVED) {
2217 <                        if ((ek = e.key) instanceof TreeBin)
2218 <                            e = ((TreeBin)ek).first;
2219 <                        else {
2220 <                            tab = (Node[])ek;
2221 <                            continue;           // restarts due to null val
2222 <                        }
2223 <                    }                           // visit upper slots if present
2224 <                    index = (i += baseSize) < n ? i : (baseIndex = b + 1);
2225 <                }
2226 <                nextKey = e.key;
2227 <            } while ((ev = e.val) == null);    // skip deleted or special nodes
2228 <            next = e;
2229 <            return nextVal = ev;
2230 <        }
799 >    private transient volatile CounterCell[] counterCells;
800  
801 <        public final void remove() {
802 <            if (nextVal == null)
803 <                advance();
804 <            Node e = last;
2236 <            if (e == null)
2237 <                throw new IllegalStateException();
2238 <            last = null;
2239 <            map.remove(e.key);
2240 <        }
2241 <
2242 <        public final boolean hasNext() {
2243 <            return nextVal != null || advance() != null;
2244 <        }
801 >    // views
802 >    private transient KeySetView<K,V> keySet;
803 >    private transient ValuesView<K,V> values;
804 >    private transient EntrySetView<K,V> entrySet;
805  
2246        public final boolean hasMoreElements() { return hasNext(); }
2247    }
806  
807      /* ---------------- Public operations -------------- */
808  
# Line 2252 | Line 810 | public class ConcurrentHashMapV8<K, V>
810       * Creates a new, empty map with the default initial table size (16).
811       */
812      public ConcurrentHashMapV8() {
2255        this.counter = new LongAdder();
813      }
814  
815      /**
# Line 2271 | Line 828 | public class ConcurrentHashMapV8<K, V>
828          int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
829                     MAXIMUM_CAPACITY :
830                     tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
2274        this.counter = new LongAdder();
831          this.sizeCtl = cap;
832      }
833  
# Line 2281 | Line 837 | public class ConcurrentHashMapV8<K, V>
837       * @param m the map
838       */
839      public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) {
2284        this.counter = new LongAdder();
840          this.sizeCtl = DEFAULT_CAPACITY;
841 <        internalPutAll(m);
841 >        putAll(m);
842      }
843  
844      /**
# Line 2324 | Line 879 | public class ConcurrentHashMapV8<K, V>
879       * nonpositive
880       */
881      public ConcurrentHashMapV8(int initialCapacity,
882 <                               float loadFactor, int concurrencyLevel) {
882 >                             float loadFactor, int concurrencyLevel) {
883          if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
884              throw new IllegalArgumentException();
885          if (initialCapacity < concurrencyLevel)   // Use at least as many bins
886              initialCapacity = concurrencyLevel;   // as estimated threads
887          long size = (long)(1.0 + (long)initialCapacity / loadFactor);
888 <        int cap = ((size >= (long)MAXIMUM_CAPACITY) ?
889 <                   MAXIMUM_CAPACITY: tableSizeFor((int)size));
2335 <        this.counter = new LongAdder();
888 >        int cap = (size >= (long)MAXIMUM_CAPACITY) ?
889 >            MAXIMUM_CAPACITY : tableSizeFor((int)size);
890          this.sizeCtl = cap;
891      }
892  
893 <    /**
2340 <     * {@inheritDoc}
2341 <     */
2342 <    public boolean isEmpty() {
2343 <        return counter.sum() <= 0L; // ignore transient negative values
2344 <    }
893 >    // Original (since JDK1.2) Map methods
894  
895      /**
896       * {@inheritDoc}
897       */
898      public int size() {
899 <        long n = counter.sum();
899 >        long n = sumCount();
900          return ((n < 0L) ? 0 :
901                  (n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
902                  (int)n);
903      }
904  
905 <    final long longSize() { // accurate version of size needed for views
906 <        long n = counter.sum();
907 <        return (n < 0L) ? 0L : n;
905 >    /**
906 >     * {@inheritDoc}
907 >     */
908 >    public boolean isEmpty() {
909 >        return sumCount() <= 0L; // ignore transient negative values
910      }
911  
912      /**
# Line 2369 | Line 920 | public class ConcurrentHashMapV8<K, V>
920       *
921       * @throws NullPointerException if the specified key is null
922       */
2372    @SuppressWarnings("unchecked")
923      public V get(Object key) {
924 <        if (key == null)
925 <            throw new NullPointerException();
926 <        return (V)internalGet(key);
924 >        Node<K,V>[] tab; Node<K,V> e, p; int n, eh; K ek;
925 >        int h = spread(key.hashCode());
926 >        if ((tab = table) != null && (n = tab.length) > 0 &&
927 >            (e = tabAt(tab, (n - 1) & h)) != null) {
928 >            if ((eh = e.hash) == h) {
929 >                if ((ek = e.key) == key || (ek != null && key.equals(ek)))
930 >                    return e.val;
931 >            }
932 >            else if (eh < 0)
933 >                return (p = e.find(h, key)) != null ? p.val : null;
934 >            while ((e = e.next) != null) {
935 >                if (e.hash == h &&
936 >                    ((ek = e.key) == key || (ek != null && key.equals(ek))))
937 >                    return e.val;
938 >            }
939 >        }
940 >        return null;
941      }
942  
943      /**
944       * Tests if the specified object is a key in this table.
945       *
946 <     * @param  key   possible key
946 >     * @param  key possible key
947       * @return {@code true} if and only if the specified object
948       *         is a key in this table, as determined by the
949       *         {@code equals} method; {@code false} otherwise
950       * @throws NullPointerException if the specified key is null
951       */
952      public boolean containsKey(Object key) {
953 <        if (key == null)
2390 <            throw new NullPointerException();
2391 <        return internalGet(key) != null;
953 >        return get(key) != null;
954      }
955  
956      /**
# Line 2404 | Line 966 | public class ConcurrentHashMapV8<K, V>
966      public boolean containsValue(Object value) {
967          if (value == null)
968              throw new NullPointerException();
969 <        Object v;
970 <        InternalIterator<K,V> it = new InternalIterator<K,V>(this);
971 <        while ((v = it.advance()) != null) {
972 <            if (v == value || value.equals(v))
973 <                return true;
969 >        Node<K,V>[] t;
970 >        if ((t = table) != null) {
971 >            Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
972 >            for (Node<K,V> p; (p = it.advance()) != null; ) {
973 >                V v;
974 >                if ((v = p.val) == value || (v != null && value.equals(v)))
975 >                    return true;
976 >            }
977          }
978          return false;
979      }
980  
981      /**
2417     * Legacy method testing if some key maps into the specified value
2418     * in this table.  This method is identical in functionality to
2419     * {@link #containsValue}, and exists solely to ensure
2420     * full compatibility with class {@link java.util.Hashtable},
2421     * which supported this method prior to introduction of the
2422     * Java Collections framework.
2423     *
2424     * @param  value a value to search for
2425     * @return {@code true} if and only if some key maps to the
2426     *         {@code value} argument in this table as
2427     *         determined by the {@code equals} method;
2428     *         {@code false} otherwise
2429     * @throws NullPointerException if the specified value is null
2430     */
2431    public boolean contains(Object value) {
2432        return containsValue(value);
2433    }
2434
2435    /**
982       * Maps the specified key to the specified value in this table.
983       * Neither the key nor the value can be null.
984       *
985 <     * <p> The value can be retrieved by calling the {@code get} method
985 >     * <p>The value can be retrieved by calling the {@code get} method
986       * with a key that is equal to the original key.
987       *
988       * @param key key with which the specified value is to be associated
# Line 2445 | Line 991 | public class ConcurrentHashMapV8<K, V>
991       *         {@code null} if there was no mapping for {@code key}
992       * @throws NullPointerException if the specified key or value is null
993       */
2448    @SuppressWarnings("unchecked")
994      public V put(K key, V value) {
995 <        if (key == null || value == null)
2451 <            throw new NullPointerException();
2452 <        return (V)internalPut(key, value);
995 >        return putVal(key, value, false);
996      }
997  
998 <    /**
999 <     * {@inheritDoc}
1000 <     *
1001 <     * @return the previous value associated with the specified key,
1002 <     *         or {@code null} if there was no mapping for the key
1003 <     * @throws NullPointerException if the specified key or value is null
1004 <     */
1005 <    @SuppressWarnings("unchecked")
1006 <    public V putIfAbsent(K key, V value) {
1007 <        if (key == null || value == null)
1008 <            throw new NullPointerException();
1009 <        return (V)internalPutIfAbsent(key, value);
998 >    /** Implementation for put and putIfAbsent */
999 >    final V putVal(K key, V value, boolean onlyIfAbsent) {
1000 >        if (key == null || value == null) throw new NullPointerException();
1001 >        int hash = spread(key.hashCode());
1002 >        int binCount = 0;
1003 >        for (Node<K,V>[] tab = table;;) {
1004 >            Node<K,V> f; int n, i, fh;
1005 >            if (tab == null || (n = tab.length) == 0)
1006 >                tab = initTable();
1007 >            else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
1008 >                if (casTabAt(tab, i, null,
1009 >                             new Node<K,V>(hash, key, value, null)))
1010 >                    break;                   // no lock when adding to empty bin
1011 >            }
1012 >            else if ((fh = f.hash) == MOVED)
1013 >                tab = helpTransfer(tab, f);
1014 >            else {
1015 >                V oldVal = null;
1016 >                synchronized (f) {
1017 >                    if (tabAt(tab, i) == f) {
1018 >                        if (fh >= 0) {
1019 >                            binCount = 1;
1020 >                            for (Node<K,V> e = f;; ++binCount) {
1021 >                                K ek;
1022 >                                if (e.hash == hash &&
1023 >                                    ((ek = e.key) == key ||
1024 >                                     (ek != null && key.equals(ek)))) {
1025 >                                    oldVal = e.val;
1026 >                                    if (!onlyIfAbsent)
1027 >                                        e.val = value;
1028 >                                    break;
1029 >                                }
1030 >                                Node<K,V> pred = e;
1031 >                                if ((e = e.next) == null) {
1032 >                                    pred.next = new Node<K,V>(hash, key,
1033 >                                                              value, null);
1034 >                                    break;
1035 >                                }
1036 >                            }
1037 >                        }
1038 >                        else if (f instanceof TreeBin) {
1039 >                            Node<K,V> p;
1040 >                            binCount = 2;
1041 >                            if ((p = ((TreeBin<K,V>)f).putTreeVal(hash, key,
1042 >                                                           value)) != null) {
1043 >                                oldVal = p.val;
1044 >                                if (!onlyIfAbsent)
1045 >                                    p.val = value;
1046 >                            }
1047 >                        }
1048 >                    }
1049 >                }
1050 >                if (binCount != 0) {
1051 >                    if (binCount >= TREEIFY_THRESHOLD)
1052 >                        treeifyBin(tab, i);
1053 >                    if (oldVal != null)
1054 >                        return oldVal;
1055 >                    break;
1056 >                }
1057 >            }
1058 >        }
1059 >        addCount(1L, binCount);
1060 >        return null;
1061      }
1062  
1063      /**
# Line 2474 | Line 1068 | public class ConcurrentHashMapV8<K, V>
1068       * @param m mappings to be stored in this map
1069       */
1070      public void putAll(Map<? extends K, ? extends V> m) {
1071 <        internalPutAll(m);
1072 <    }
1073 <
2480 <    /**
2481 <     * If the specified key is not already associated with a value,
2482 <     * computes its value using the given mappingFunction and enters
2483 <     * it into the map unless null.  This is equivalent to
2484 <     * <pre> {@code
2485 <     * if (map.containsKey(key))
2486 <     *   return map.get(key);
2487 <     * value = mappingFunction.map(key);
2488 <     * if (value != null)
2489 <     *   map.put(key, value);
2490 <     * return value;}</pre>
2491 <     *
2492 <     * except that the action is performed atomically.  If the
2493 <     * function returns {@code null} no mapping is recorded. If the
2494 <     * function itself throws an (unchecked) exception, the exception
2495 <     * is rethrown to its caller, and no mapping is recorded.  Some
2496 <     * attempted update operations on this map by other threads may be
2497 <     * blocked while computation is in progress, so the computation
2498 <     * should be short and simple, and must not attempt to update any
2499 <     * other mappings of this Map. The most appropriate usage is to
2500 <     * construct a new object serving as an initial mapped value, or
2501 <     * memoized result, as in:
2502 <     *
2503 <     *  <pre> {@code
2504 <     * map.computeIfAbsent(key, new MappingFunction<K, V>() {
2505 <     *   public V map(K k) { return new Value(f(k)); }});}</pre>
2506 <     *
2507 <     * @param key key with which the specified value is to be associated
2508 <     * @param mappingFunction the function to compute a value
2509 <     * @return the current (existing or computed) value associated with
2510 <     *         the specified key, or null if the computed value is null.
2511 <     * @throws NullPointerException if the specified key or mappingFunction
2512 <     *         is null
2513 <     * @throws IllegalStateException if the computation detectably
2514 <     *         attempts a recursive update to this map that would
2515 <     *         otherwise never complete
2516 <     * @throws RuntimeException or Error if the mappingFunction does so,
2517 <     *         in which case the mapping is left unestablished
2518 <     */
2519 <    @SuppressWarnings("unchecked")
2520 <    public V computeIfAbsent(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2521 <        if (key == null || mappingFunction == null)
2522 <            throw new NullPointerException();
2523 <        return (V)internalComputeIfAbsent(key, mappingFunction);
2524 <    }
2525 <
2526 <    /**
2527 <     * Computes a new mapping value given a key and
2528 <     * its current mapped value (or {@code null} if there is no current
2529 <     * mapping). This is equivalent to
2530 <     *  <pre> {@code
2531 <     *   value = remappingFunction.remap(key, map.get(key));
2532 <     *   if (value != null)
2533 <     *     map.put(key, value);
2534 <     *   else
2535 <     *     map.remove(key);
2536 <     * }</pre>
2537 <     *
2538 <     * except that the action is performed atomically.  If the
2539 <     * function returns {@code null}, the mapping is removed.  If the
2540 <     * function itself throws an (unchecked) exception, the exception
2541 <     * is rethrown to its caller, and the current mapping is left
2542 <     * unchanged.  Some attempted update operations on this map by
2543 <     * other threads may be blocked while computation is in progress,
2544 <     * so the computation should be short and simple, and must not
2545 <     * attempt to update any other mappings of this Map. For example,
2546 <     * to either create or append new messages to a value mapping:
2547 <     *
2548 <     * <pre> {@code
2549 <     * Map<Key, String> map = ...;
2550 <     * final String msg = ...;
2551 <     * map.compute(key, new RemappingFunction<Key, String>() {
2552 <     *   public String remap(Key k, String v) {
2553 <     *    return (v == null) ? msg : v + msg;});}}</pre>
2554 <     *
2555 <     * @param key key with which the specified value is to be associated
2556 <     * @param remappingFunction the function to compute a value
2557 <     * @return the new value associated with
2558 <     *         the specified key, or null if none.
2559 <     * @throws NullPointerException if the specified key or remappingFunction
2560 <     *         is null
2561 <     * @throws IllegalStateException if the computation detectably
2562 <     *         attempts a recursive update to this map that would
2563 <     *         otherwise never complete
2564 <     * @throws RuntimeException or Error if the remappingFunction does so,
2565 <     *         in which case the mapping is unchanged
2566 <     */
2567 <    @SuppressWarnings("unchecked")
2568 <    public V compute(K key, RemappingFunction<? super K, V> remappingFunction) {
2569 <        if (key == null || remappingFunction == null)
2570 <            throw new NullPointerException();
2571 <        return (V)internalCompute(key, remappingFunction);
1071 >        tryPresize(m.size());
1072 >        for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
1073 >            putVal(e.getKey(), e.getValue(), false);
1074      }
1075  
1076      /**
# Line 2580 | Line 1082 | public class ConcurrentHashMapV8<K, V>
1082       *         {@code null} if there was no mapping for {@code key}
1083       * @throws NullPointerException if the specified key is null
1084       */
2583    @SuppressWarnings("unchecked")
1085      public V remove(Object key) {
1086 <        if (key == null)
2586 <            throw new NullPointerException();
2587 <        return (V)internalReplace(key, null, null);
2588 <    }
2589 <
2590 <    /**
2591 <     * {@inheritDoc}
2592 <     *
2593 <     * @throws NullPointerException if the specified key is null
2594 <     */
2595 <    public boolean remove(Object key, Object value) {
2596 <        if (key == null)
2597 <            throw new NullPointerException();
2598 <        if (value == null)
2599 <            return false;
2600 <        return internalReplace(key, null, value) != null;
2601 <    }
2602 <
2603 <    /**
2604 <     * {@inheritDoc}
2605 <     *
2606 <     * @throws NullPointerException if any of the arguments are null
2607 <     */
2608 <    public boolean replace(K key, V oldValue, V newValue) {
2609 <        if (key == null || oldValue == null || newValue == null)
2610 <            throw new NullPointerException();
2611 <        return internalReplace(key, newValue, oldValue) != null;
1086 >        return replaceNode(key, null, null);
1087      }
1088  
1089      /**
1090 <     * {@inheritDoc}
1091 <     *
1092 <     * @return the previous value associated with the specified key,
2618 <     *         or {@code null} if there was no mapping for the key
2619 <     * @throws NullPointerException if the specified key or value is null
1090 >     * Implementation for the four public remove/replace methods:
1091 >     * Replaces node value with v, conditional upon match of cv if
1092 >     * non-null.  If resulting value is null, delete.
1093       */
1094 <    @SuppressWarnings("unchecked")
1095 <    public V replace(K key, V value) {
1096 <        if (key == null || value == null)
1097 <            throw new NullPointerException();
1098 <        return (V)internalReplace(key, value, null);
1094 >    final V replaceNode(Object key, V value, Object cv) {
1095 >        int hash = spread(key.hashCode());
1096 >        for (Node<K,V>[] tab = table;;) {
1097 >            Node<K,V> f; int n, i, fh;
1098 >            if (tab == null || (n = tab.length) == 0 ||
1099 >                (f = tabAt(tab, i = (n - 1) & hash)) == null)
1100 >                break;
1101 >            else if ((fh = f.hash) == MOVED)
1102 >                tab = helpTransfer(tab, f);
1103 >            else {
1104 >                V oldVal = null;
1105 >                boolean validated = false;
1106 >                synchronized (f) {
1107 >                    if (tabAt(tab, i) == f) {
1108 >                        if (fh >= 0) {
1109 >                            validated = true;
1110 >                            for (Node<K,V> e = f, pred = null;;) {
1111 >                                K ek;
1112 >                                if (e.hash == hash &&
1113 >                                    ((ek = e.key) == key ||
1114 >                                     (ek != null && key.equals(ek)))) {
1115 >                                    V ev = e.val;
1116 >                                    if (cv == null || cv == ev ||
1117 >                                        (ev != null && cv.equals(ev))) {
1118 >                                        oldVal = ev;
1119 >                                        if (value != null)
1120 >                                            e.val = value;
1121 >                                        else if (pred != null)
1122 >                                            pred.next = e.next;
1123 >                                        else
1124 >                                            setTabAt(tab, i, e.next);
1125 >                                    }
1126 >                                    break;
1127 >                                }
1128 >                                pred = e;
1129 >                                if ((e = e.next) == null)
1130 >                                    break;
1131 >                            }
1132 >                        }
1133 >                        else if (f instanceof TreeBin) {
1134 >                            validated = true;
1135 >                            TreeBin<K,V> t = (TreeBin<K,V>)f;
1136 >                            TreeNode<K,V> r, p;
1137 >                            if ((r = t.root) != null &&
1138 >                                (p = r.findTreeNode(hash, key, null)) != null) {
1139 >                                V pv = p.val;
1140 >                                if (cv == null || cv == pv ||
1141 >                                    (pv != null && cv.equals(pv))) {
1142 >                                    oldVal = pv;
1143 >                                    if (value != null)
1144 >                                        p.val = value;
1145 >                                    else if (t.removeTreeNode(p))
1146 >                                        setTabAt(tab, i, untreeify(t.first));
1147 >                                }
1148 >                            }
1149 >                        }
1150 >                    }
1151 >                }
1152 >                if (validated) {
1153 >                    if (oldVal != null) {
1154 >                        if (value == null)
1155 >                            addCount(-1L, -1);
1156 >                        return oldVal;
1157 >                    }
1158 >                    break;
1159 >                }
1160 >            }
1161 >        }
1162 >        return null;
1163      }
1164  
1165      /**
1166       * Removes all of the mappings from this map.
1167       */
1168      public void clear() {
1169 <        internalClear();
1169 >        long delta = 0L; // negative number of deletions
1170 >        int i = 0;
1171 >        Node<K,V>[] tab = table;
1172 >        while (tab != null && i < tab.length) {
1173 >            int fh;
1174 >            Node<K,V> f = tabAt(tab, i);
1175 >            if (f == null)
1176 >                ++i;
1177 >            else if ((fh = f.hash) == MOVED) {
1178 >                tab = helpTransfer(tab, f);
1179 >                i = 0; // restart
1180 >            }
1181 >            else {
1182 >                synchronized (f) {
1183 >                    if (tabAt(tab, i) == f) {
1184 >                        Node<K,V> p = (fh >= 0 ? f :
1185 >                                       (f instanceof TreeBin) ?
1186 >                                       ((TreeBin<K,V>)f).first : null);
1187 >                        while (p != null) {
1188 >                            --delta;
1189 >                            p = p.next;
1190 >                        }
1191 >                        setTabAt(tab, i++, null);
1192 >                    }
1193 >                }
1194 >            }
1195 >        }
1196 >        if (delta != 0L)
1197 >            addCount(delta, -1);
1198      }
1199  
1200      /**
1201       * Returns a {@link Set} view of the keys contained in this map.
1202       * The set is backed by the map, so changes to the map are
1203 <     * reflected in the set, and vice-versa.  The set supports element
1203 >     * reflected in the set, and vice-versa. The set supports element
1204       * removal, which removes the corresponding mapping from this map,
1205       * via the {@code Iterator.remove}, {@code Set.remove},
1206       * {@code removeAll}, {@code retainAll}, and {@code clear}
# Line 2647 | Line 1212 | public class ConcurrentHashMapV8<K, V>
1212       * and guarantees to traverse elements as they existed upon
1213       * construction of the iterator, and may (but is not guaranteed to)
1214       * reflect any modifications subsequent to construction.
1215 +     *
1216 +     * @return the set view
1217       */
1218 <    public Set<K> keySet() {
1219 <        KeySet<K,V> ks = keySet;
1220 <        return (ks != null) ? ks : (keySet = new KeySet<K,V>(this));
1218 >    public KeySetView<K,V> keySet() {
1219 >        KeySetView<K,V> ks;
1220 >        return (ks = keySet) != null ? ks : (keySet = new KeySetView<K,V>(this, null));
1221      }
1222  
1223      /**
# Line 2668 | Line 1235 | public class ConcurrentHashMapV8<K, V>
1235       * and guarantees to traverse elements as they existed upon
1236       * construction of the iterator, and may (but is not guaranteed to)
1237       * reflect any modifications subsequent to construction.
1238 +     *
1239 +     * @return the collection view
1240       */
1241      public Collection<V> values() {
1242 <        Values<K,V> vs = values;
1243 <        return (vs != null) ? vs : (values = new Values<K,V>(this));
1242 >        ValuesView<K,V> vs;
1243 >        return (vs = values) != null ? vs : (values = new ValuesView<K,V>(this));
1244      }
1245  
1246      /**
# Line 2681 | Line 1250 | public class ConcurrentHashMapV8<K, V>
1250       * removal, which removes the corresponding mapping from the map,
1251       * via the {@code Iterator.remove}, {@code Set.remove},
1252       * {@code removeAll}, {@code retainAll}, and {@code clear}
1253 <     * operations.  It does not support the {@code add} or
2685 <     * {@code addAll} operations.
1253 >     * operations.
1254       *
1255       * <p>The view's {@code iterator} is a "weakly consistent" iterator
1256       * that will never throw {@link ConcurrentModificationException},
1257       * and guarantees to traverse elements as they existed upon
1258       * construction of the iterator, and may (but is not guaranteed to)
1259       * reflect any modifications subsequent to construction.
2692     */
2693    public Set<Map.Entry<K,V>> entrySet() {
2694        EntrySet<K,V> es = entrySet;
2695        return (es != null) ? es : (entrySet = new EntrySet<K,V>(this));
2696    }
2697
2698    /**
2699     * Returns an enumeration of the keys in this table.
1260       *
1261 <     * @return an enumeration of the keys in this table
2702 <     * @see #keySet()
1261 >     * @return the set view
1262       */
1263 <    public Enumeration<K> keys() {
1264 <        return new KeyIterator<K,V>(this);
1265 <    }
2707 <
2708 <    /**
2709 <     * Returns an enumeration of the values in this table.
2710 <     *
2711 <     * @return an enumeration of the values in this table
2712 <     * @see #values()
2713 <     */
2714 <    public Enumeration<V> elements() {
2715 <        return new ValueIterator<K,V>(this);
2716 <    }
2717 <
2718 <    /**
2719 <     * Returns a partionable iterator of the keys in this map.
2720 <     *
2721 <     * @return a partionable iterator of the keys in this map
2722 <     */
2723 <    public Spliterator<K> keySpliterator() {
2724 <        return new KeyIterator<K,V>(this);
2725 <    }
2726 <
2727 <    /**
2728 <     * Returns a partionable iterator of the values in this map.
2729 <     *
2730 <     * @return a partionable iterator of the values in this map
2731 <     */
2732 <    public Spliterator<V> valueSpliterator() {
2733 <        return new ValueIterator<K,V>(this);
2734 <    }
2735 <
2736 <    /**
2737 <     * Returns a partionable iterator of the entries in this map.
2738 <     *
2739 <     * @return a partionable iterator of the entries in this map
2740 <     */
2741 <    public Spliterator<Map.Entry<K,V>> entrySpliterator() {
2742 <        return new EntryIterator<K,V>(this);
1263 >    public Set<Map.Entry<K,V>> entrySet() {
1264 >        EntrySetView<K,V> es;
1265 >        return (es = entrySet) != null ? es : (entrySet = new EntrySetView<K,V>(this));
1266      }
1267  
1268      /**
# Line 2751 | Line 1274 | public class ConcurrentHashMapV8<K, V>
1274       */
1275      public int hashCode() {
1276          int h = 0;
1277 <        InternalIterator<K,V> it = new InternalIterator<K,V>(this);
1278 <        Object v;
1279 <        while ((v = it.advance()) != null) {
1280 <            h += it.nextKey.hashCode() ^ v.hashCode();
1277 >        Node<K,V>[] t;
1278 >        if ((t = table) != null) {
1279 >            Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1280 >            for (Node<K,V> p; (p = it.advance()) != null; )
1281 >                h += p.key.hashCode() ^ p.val.hashCode();
1282          }
1283          return h;
1284      }
# Line 2771 | Line 1295 | public class ConcurrentHashMapV8<K, V>
1295       * @return a string representation of this map
1296       */
1297      public String toString() {
1298 <        InternalIterator<K,V> it = new InternalIterator<K,V>(this);
1298 >        Node<K,V>[] t;
1299 >        int f = (t = table) == null ? 0 : t.length;
1300 >        Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1301          StringBuilder sb = new StringBuilder();
1302          sb.append('{');
1303 <        Object v;
1304 <        if ((v = it.advance()) != null) {
1303 >        Node<K,V> p;
1304 >        if ((p = it.advance()) != null) {
1305              for (;;) {
1306 <                Object k = it.nextKey;
1306 >                K k = p.key;
1307 >                V v = p.val;
1308                  sb.append(k == this ? "(this Map)" : k);
1309                  sb.append('=');
1310                  sb.append(v == this ? "(this Map)" : v);
1311 <                if ((v = it.advance()) == null)
1311 >                if ((p = it.advance()) == null)
1312                      break;
1313                  sb.append(',').append(' ');
1314              }
# Line 2804 | Line 1331 | public class ConcurrentHashMapV8<K, V>
1331              if (!(o instanceof Map))
1332                  return false;
1333              Map<?,?> m = (Map<?,?>) o;
1334 <            InternalIterator<K,V> it = new InternalIterator<K,V>(this);
1335 <            Object val;
1336 <            while ((val = it.advance()) != null) {
1337 <                Object v = m.get(it.nextKey);
1334 >            Node<K,V>[] t;
1335 >            int f = (t = table) == null ? 0 : t.length;
1336 >            Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1337 >            for (Node<K,V> p; (p = it.advance()) != null; ) {
1338 >                V val = p.val;
1339 >                Object v = m.get(p.key);
1340                  if (v == null || (v != val && !v.equals(val)))
1341                      return false;
1342              }
# Line 2815 | Line 1344 | public class ConcurrentHashMapV8<K, V>
1344                  Object mk, mv, v;
1345                  if ((mk = e.getKey()) == null ||
1346                      (mv = e.getValue()) == null ||
1347 <                    (v = internalGet(mk)) == null ||
1347 >                    (v = get(mk)) == null ||
1348                      (mv != v && !mv.equals(v)))
1349                      return false;
1350              }
# Line 2823 | Line 1352 | public class ConcurrentHashMapV8<K, V>
1352          return true;
1353      }
1354  
1355 <    /* ----------------Iterators -------------- */
1355 >    /**
1356 >     * Stripped-down version of helper class used in previous version,
1357 >     * declared for the sake of serialization compatibility
1358 >     */
1359 >    static class Segment<K,V> extends ReentrantLock implements Serializable {
1360 >        private static final long serialVersionUID = 2249069246763182397L;
1361 >        final float loadFactor;
1362 >        Segment(float lf) { this.loadFactor = lf; }
1363 >    }
1364  
1365 <    static final class KeyIterator<K,V> extends InternalIterator<K,V>
1366 <        implements Spliterator<K>, Enumeration<K> {
1367 <        KeyIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
1368 <        KeyIterator(InternalIterator<K,V> it, boolean split) {
1369 <            super(it, split);
1365 >    /**
1366 >     * Saves the state of the {@code ConcurrentHashMapV8} instance to a
1367 >     * stream (i.e., serializes it).
1368 >     * @param s the stream
1369 >     * @throws java.io.IOException if an I/O error occurs
1370 >     * @serialData
1371 >     * the key (Object) and value (Object)
1372 >     * for each key-value mapping, followed by a null pair.
1373 >     * The key-value mappings are emitted in no particular order.
1374 >     */
1375 >    private void writeObject(java.io.ObjectOutputStream s)
1376 >        throws java.io.IOException {
1377 >        // For serialization compatibility
1378 >        // Emulate segment calculation from previous version of this class
1379 >        int sshift = 0;
1380 >        int ssize = 1;
1381 >        while (ssize < DEFAULT_CONCURRENCY_LEVEL) {
1382 >            ++sshift;
1383 >            ssize <<= 1;
1384 >        }
1385 >        int segmentShift = 32 - sshift;
1386 >        int segmentMask = ssize - 1;
1387 >        @SuppressWarnings("unchecked") Segment<K,V>[] segments = (Segment<K,V>[])
1388 >            new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
1389 >        for (int i = 0; i < segments.length; ++i)
1390 >            segments[i] = new Segment<K,V>(LOAD_FACTOR);
1391 >        s.putFields().put("segments", segments);
1392 >        s.putFields().put("segmentShift", segmentShift);
1393 >        s.putFields().put("segmentMask", segmentMask);
1394 >        s.writeFields();
1395 >
1396 >        Node<K,V>[] t;
1397 >        if ((t = table) != null) {
1398 >            Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1399 >            for (Node<K,V> p; (p = it.advance()) != null; ) {
1400 >                s.writeObject(p.key);
1401 >                s.writeObject(p.val);
1402 >            }
1403          }
1404 <        public KeyIterator<K,V> split() {
1405 <            if (last != null || (next != null && nextVal == null))
1406 <                throw new IllegalStateException();
1407 <            return new KeyIterator<K,V>(this, true);
1404 >        s.writeObject(null);
1405 >        s.writeObject(null);
1406 >        segments = null; // throw away
1407 >    }
1408 >
1409 >    /**
1410 >     * Reconstitutes the instance from a stream (that is, deserializes it).
1411 >     * @param s the stream
1412 >     * @throws ClassNotFoundException if the class of a serialized object
1413 >     *         could not be found
1414 >     * @throws java.io.IOException if an I/O error occurs
1415 >     */
1416 >    private void readObject(java.io.ObjectInputStream s)
1417 >        throws java.io.IOException, ClassNotFoundException {
1418 >        /*
1419 >         * To improve performance in typical cases, we create nodes
1420 >         * while reading, then place in table once size is known.
1421 >         * However, we must also validate uniqueness and deal with
1422 >         * overpopulated bins while doing so, which requires
1423 >         * specialized versions of putVal mechanics.
1424 >         */
1425 >        sizeCtl = -1; // force exclusion for table construction
1426 >        s.defaultReadObject();
1427 >        long size = 0L;
1428 >        Node<K,V> p = null;
1429 >        for (;;) {
1430 >            @SuppressWarnings("unchecked") K k = (K) s.readObject();
1431 >            @SuppressWarnings("unchecked") V v = (V) s.readObject();
1432 >            if (k != null && v != null) {
1433 >                p = new Node<K,V>(spread(k.hashCode()), k, v, p);
1434 >                ++size;
1435 >            }
1436 >            else
1437 >                break;
1438          }
1439 <        public KeyIterator<K,V> clone() {
1440 <            if (last != null || (next != null && nextVal == null))
1441 <                throw new IllegalStateException();
1442 <            return new KeyIterator<K,V>(this, false);
1439 >        if (size == 0L)
1440 >            sizeCtl = 0;
1441 >        else {
1442 >            int n;
1443 >            if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
1444 >                n = MAXIMUM_CAPACITY;
1445 >            else {
1446 >                int sz = (int)size;
1447 >                n = tableSizeFor(sz + (sz >>> 1) + 1);
1448 >            }
1449 >            @SuppressWarnings("unchecked")
1450 >                Node<K,V>[] tab = (Node<K,V>[])new Node<?,?>[n];
1451 >            int mask = n - 1;
1452 >            long added = 0L;
1453 >            while (p != null) {
1454 >                boolean insertAtFront;
1455 >                Node<K,V> next = p.next, first;
1456 >                int h = p.hash, j = h & mask;
1457 >                if ((first = tabAt(tab, j)) == null)
1458 >                    insertAtFront = true;
1459 >                else {
1460 >                    K k = p.key;
1461 >                    if (first.hash < 0) {
1462 >                        TreeBin<K,V> t = (TreeBin<K,V>)first;
1463 >                        if (t.putTreeVal(h, k, p.val) == null)
1464 >                            ++added;
1465 >                        insertAtFront = false;
1466 >                    }
1467 >                    else {
1468 >                        int binCount = 0;
1469 >                        insertAtFront = true;
1470 >                        Node<K,V> q; K qk;
1471 >                        for (q = first; q != null; q = q.next) {
1472 >                            if (q.hash == h &&
1473 >                                ((qk = q.key) == k ||
1474 >                                 (qk != null && k.equals(qk)))) {
1475 >                                insertAtFront = false;
1476 >                                break;
1477 >                            }
1478 >                            ++binCount;
1479 >                        }
1480 >                        if (insertAtFront && binCount >= TREEIFY_THRESHOLD) {
1481 >                            insertAtFront = false;
1482 >                            ++added;
1483 >                            p.next = first;
1484 >                            TreeNode<K,V> hd = null, tl = null;
1485 >                            for (q = p; q != null; q = q.next) {
1486 >                                TreeNode<K,V> t = new TreeNode<K,V>
1487 >                                    (q.hash, q.key, q.val, null, null);
1488 >                                if ((t.prev = tl) == null)
1489 >                                    hd = t;
1490 >                                else
1491 >                                    tl.next = t;
1492 >                                tl = t;
1493 >                            }
1494 >                            setTabAt(tab, j, new TreeBin<K,V>(hd));
1495 >                        }
1496 >                    }
1497 >                }
1498 >                if (insertAtFront) {
1499 >                    ++added;
1500 >                    p.next = first;
1501 >                    setTabAt(tab, j, p);
1502 >                }
1503 >                p = next;
1504 >            }
1505 >            table = tab;
1506 >            sizeCtl = n - (n >>> 2);
1507 >            baseCount = added;
1508          }
1509 +    }
1510  
1511 <        @SuppressWarnings("unchecked")
1512 <        public final K next() {
1513 <            if (nextVal == null && advance() == null)
1514 <                throw new NoSuchElementException();
1515 <            Object k = nextKey;
1516 <            nextVal = null;
1517 <            return (K) k;
1511 >    // ConcurrentMap methods
1512 >
1513 >    /**
1514 >     * {@inheritDoc}
1515 >     *
1516 >     * @return the previous value associated with the specified key,
1517 >     *         or {@code null} if there was no mapping for the key
1518 >     * @throws NullPointerException if the specified key or value is null
1519 >     */
1520 >    public V putIfAbsent(K key, V value) {
1521 >        return putVal(key, value, true);
1522 >    }
1523 >
1524 >    /**
1525 >     * {@inheritDoc}
1526 >     *
1527 >     * @throws NullPointerException if the specified key is null
1528 >     */
1529 >    public boolean remove(Object key, Object value) {
1530 >        if (key == null)
1531 >            throw new NullPointerException();
1532 >        return value != null && replaceNode(key, null, value) != null;
1533 >    }
1534 >
1535 >    /**
1536 >     * {@inheritDoc}
1537 >     *
1538 >     * @throws NullPointerException if any of the arguments are null
1539 >     */
1540 >    public boolean replace(K key, V oldValue, V newValue) {
1541 >        if (key == null || oldValue == null || newValue == null)
1542 >            throw new NullPointerException();
1543 >        return replaceNode(key, newValue, oldValue) != null;
1544 >    }
1545 >
1546 >    /**
1547 >     * {@inheritDoc}
1548 >     *
1549 >     * @return the previous value associated with the specified key,
1550 >     *         or {@code null} if there was no mapping for the key
1551 >     * @throws NullPointerException if the specified key or value is null
1552 >     */
1553 >    public V replace(K key, V value) {
1554 >        if (key == null || value == null)
1555 >            throw new NullPointerException();
1556 >        return replaceNode(key, value, null);
1557 >    }
1558 >
1559 >    // Overrides of JDK8+ Map extension method defaults
1560 >
1561 >    /**
1562 >     * Returns the value to which the specified key is mapped, or the
1563 >     * given default value if this map contains no mapping for the
1564 >     * key.
1565 >     *
1566 >     * @param key the key whose associated value is to be returned
1567 >     * @param defaultValue the value to return if this map contains
1568 >     * no mapping for the given key
1569 >     * @return the mapping for the key, if present; else the default value
1570 >     * @throws NullPointerException if the specified key is null
1571 >     */
1572 >    public V getOrDefault(Object key, V defaultValue) {
1573 >        V v;
1574 >        return (v = get(key)) == null ? defaultValue : v;
1575 >    }
1576 >
1577 >    public void forEach(BiAction<? super K, ? super V> action) {
1578 >        if (action == null) throw new NullPointerException();
1579 >        Node<K,V>[] t;
1580 >        if ((t = table) != null) {
1581 >            Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1582 >            for (Node<K,V> p; (p = it.advance()) != null; ) {
1583 >                action.apply(p.key, p.val);
1584 >            }
1585          }
1586 +    }
1587  
1588 <        public final K nextElement() { return next(); }
1588 >    public void replaceAll(BiFun<? super K, ? super V, ? extends V> function) {
1589 >        if (function == null) throw new NullPointerException();
1590 >        Node<K,V>[] t;
1591 >        if ((t = table) != null) {
1592 >            Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1593 >            for (Node<K,V> p; (p = it.advance()) != null; ) {
1594 >                V oldValue = p.val;
1595 >                for (K key = p.key;;) {
1596 >                    V newValue = function.apply(key, oldValue);
1597 >                    if (newValue == null)
1598 >                        throw new NullPointerException();
1599 >                    if (replaceNode(key, newValue, oldValue) != null ||
1600 >                        (oldValue = get(key)) == null)
1601 >                        break;
1602 >                }
1603 >            }
1604 >        }
1605      }
1606  
1607 <    static final class ValueIterator<K,V> extends InternalIterator<K,V>
1608 <        implements Spliterator<V>, Enumeration<V> {
1609 <        ValueIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
1610 <        ValueIterator(InternalIterator<K,V> it, boolean split) {
1611 <            super(it, split);
1607 >    /**
1608 >     * If the specified key is not already associated with a value,
1609 >     * attempts to compute its value using the given mapping function
1610 >     * and enters it into this map unless {@code null}.  The entire
1611 >     * method invocation is performed atomically, so the function is
1612 >     * applied at most once per key.  Some attempted update operations
1613 >     * on this map by other threads may be blocked while computation
1614 >     * is in progress, so the computation should be short and simple,
1615 >     * and must not attempt to update any other mappings of this map.
1616 >     *
1617 >     * @param key key with which the specified value is to be associated
1618 >     * @param mappingFunction the function to compute a value
1619 >     * @return the current (existing or computed) value associated with
1620 >     *         the specified key, or null if the computed value is null
1621 >     * @throws NullPointerException if the specified key or mappingFunction
1622 >     *         is null
1623 >     * @throws IllegalStateException if the computation detectably
1624 >     *         attempts a recursive update to this map that would
1625 >     *         otherwise never complete
1626 >     * @throws RuntimeException or Error if the mappingFunction does so,
1627 >     *         in which case the mapping is left unestablished
1628 >     */
1629 >    public V computeIfAbsent(K key, Fun<? super K, ? extends V> mappingFunction) {
1630 >        if (key == null || mappingFunction == null)
1631 >            throw new NullPointerException();
1632 >        int h = spread(key.hashCode());
1633 >        V val = null;
1634 >        int binCount = 0;
1635 >        for (Node<K,V>[] tab = table;;) {
1636 >            Node<K,V> f; int n, i, fh;
1637 >            if (tab == null || (n = tab.length) == 0)
1638 >                tab = initTable();
1639 >            else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1640 >                Node<K,V> r = new ReservationNode<K,V>();
1641 >                synchronized (r) {
1642 >                    if (casTabAt(tab, i, null, r)) {
1643 >                        binCount = 1;
1644 >                        Node<K,V> node = null;
1645 >                        try {
1646 >                            if ((val = mappingFunction.apply(key)) != null)
1647 >                                node = new Node<K,V>(h, key, val, null);
1648 >                        } finally {
1649 >                            setTabAt(tab, i, node);
1650 >                        }
1651 >                    }
1652 >                }
1653 >                if (binCount != 0)
1654 >                    break;
1655 >            }
1656 >            else if ((fh = f.hash) == MOVED)
1657 >                tab = helpTransfer(tab, f);
1658 >            else {
1659 >                boolean added = false;
1660 >                synchronized (f) {
1661 >                    if (tabAt(tab, i) == f) {
1662 >                        if (fh >= 0) {
1663 >                            binCount = 1;
1664 >                            for (Node<K,V> e = f;; ++binCount) {
1665 >                                K ek; V ev;
1666 >                                if (e.hash == h &&
1667 >                                    ((ek = e.key) == key ||
1668 >                                     (ek != null && key.equals(ek)))) {
1669 >                                    val = e.val;
1670 >                                    break;
1671 >                                }
1672 >                                Node<K,V> pred = e;
1673 >                                if ((e = e.next) == null) {
1674 >                                    if ((val = mappingFunction.apply(key)) != null) {
1675 >                                        added = true;
1676 >                                        pred.next = new Node<K,V>(h, key, val, null);
1677 >                                    }
1678 >                                    break;
1679 >                                }
1680 >                            }
1681 >                        }
1682 >                        else if (f instanceof TreeBin) {
1683 >                            binCount = 2;
1684 >                            TreeBin<K,V> t = (TreeBin<K,V>)f;
1685 >                            TreeNode<K,V> r, p;
1686 >                            if ((r = t.root) != null &&
1687 >                                (p = r.findTreeNode(h, key, null)) != null)
1688 >                                val = p.val;
1689 >                            else if ((val = mappingFunction.apply(key)) != null) {
1690 >                                added = true;
1691 >                                t.putTreeVal(h, key, val);
1692 >                            }
1693 >                        }
1694 >                    }
1695 >                }
1696 >                if (binCount != 0) {
1697 >                    if (binCount >= TREEIFY_THRESHOLD)
1698 >                        treeifyBin(tab, i);
1699 >                    if (!added)
1700 >                        return val;
1701 >                    break;
1702 >                }
1703 >            }
1704          }
1705 <        public ValueIterator<K,V> split() {
1706 <            if (last != null || (next != null && nextVal == null))
1707 <                throw new IllegalStateException();
1708 <            return new ValueIterator<K,V>(this, true);
1705 >        if (val != null)
1706 >            addCount(1L, binCount);
1707 >        return val;
1708 >    }
1709 >
1710 >    /**
1711 >     * If the value for the specified key is present, attempts to
1712 >     * compute a new mapping given the key and its current mapped
1713 >     * value.  The entire method invocation is performed atomically.
1714 >     * Some attempted update operations on this map by other threads
1715 >     * may be blocked while computation is in progress, so the
1716 >     * computation should be short and simple, and must not attempt to
1717 >     * update any other mappings of this map.
1718 >     *
1719 >     * @param key key with which a value may be associated
1720 >     * @param remappingFunction the function to compute a value
1721 >     * @return the new value associated with the specified key, or null if none
1722 >     * @throws NullPointerException if the specified key or remappingFunction
1723 >     *         is null
1724 >     * @throws IllegalStateException if the computation detectably
1725 >     *         attempts a recursive update to this map that would
1726 >     *         otherwise never complete
1727 >     * @throws RuntimeException or Error if the remappingFunction does so,
1728 >     *         in which case the mapping is unchanged
1729 >     */
1730 >    public V computeIfPresent(K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) {
1731 >        if (key == null || remappingFunction == null)
1732 >            throw new NullPointerException();
1733 >        int h = spread(key.hashCode());
1734 >        V val = null;
1735 >        int delta = 0;
1736 >        int binCount = 0;
1737 >        for (Node<K,V>[] tab = table;;) {
1738 >            Node<K,V> f; int n, i, fh;
1739 >            if (tab == null || (n = tab.length) == 0)
1740 >                tab = initTable();
1741 >            else if ((f = tabAt(tab, i = (n - 1) & h)) == null)
1742 >                break;
1743 >            else if ((fh = f.hash) == MOVED)
1744 >                tab = helpTransfer(tab, f);
1745 >            else {
1746 >                synchronized (f) {
1747 >                    if (tabAt(tab, i) == f) {
1748 >                        if (fh >= 0) {
1749 >                            binCount = 1;
1750 >                            for (Node<K,V> e = f, pred = null;; ++binCount) {
1751 >                                K ek;
1752 >                                if (e.hash == h &&
1753 >                                    ((ek = e.key) == key ||
1754 >                                     (ek != null && key.equals(ek)))) {
1755 >                                    val = remappingFunction.apply(key, e.val);
1756 >                                    if (val != null)
1757 >                                        e.val = val;
1758 >                                    else {
1759 >                                        delta = -1;
1760 >                                        Node<K,V> en = e.next;
1761 >                                        if (pred != null)
1762 >                                            pred.next = en;
1763 >                                        else
1764 >                                            setTabAt(tab, i, en);
1765 >                                    }
1766 >                                    break;
1767 >                                }
1768 >                                pred = e;
1769 >                                if ((e = e.next) == null)
1770 >                                    break;
1771 >                            }
1772 >                        }
1773 >                        else if (f instanceof TreeBin) {
1774 >                            binCount = 2;
1775 >                            TreeBin<K,V> t = (TreeBin<K,V>)f;
1776 >                            TreeNode<K,V> r, p;
1777 >                            if ((r = t.root) != null &&
1778 >                                (p = r.findTreeNode(h, key, null)) != null) {
1779 >                                val = remappingFunction.apply(key, p.val);
1780 >                                if (val != null)
1781 >                                    p.val = val;
1782 >                                else {
1783 >                                    delta = -1;
1784 >                                    if (t.removeTreeNode(p))
1785 >                                        setTabAt(tab, i, untreeify(t.first));
1786 >                                }
1787 >                            }
1788 >                        }
1789 >                    }
1790 >                }
1791 >                if (binCount != 0)
1792 >                    break;
1793 >            }
1794 >        }
1795 >        if (delta != 0)
1796 >            addCount((long)delta, binCount);
1797 >        return val;
1798 >    }
1799 >
1800 >    /**
1801 >     * Attempts to compute a mapping for the specified key and its
1802 >     * current mapped value (or {@code null} if there is no current
1803 >     * mapping). The entire method invocation is performed atomically.
1804 >     * Some attempted update operations on this map by other threads
1805 >     * may be blocked while computation is in progress, so the
1806 >     * computation should be short and simple, and must not attempt to
1807 >     * update any other mappings of this Map.
1808 >     *
1809 >     * @param key key with which the specified value is to be associated
1810 >     * @param remappingFunction the function to compute a value
1811 >     * @return the new value associated with the specified key, or null if none
1812 >     * @throws NullPointerException if the specified key or remappingFunction
1813 >     *         is null
1814 >     * @throws IllegalStateException if the computation detectably
1815 >     *         attempts a recursive update to this map that would
1816 >     *         otherwise never complete
1817 >     * @throws RuntimeException or Error if the remappingFunction does so,
1818 >     *         in which case the mapping is unchanged
1819 >     */
1820 >    public V compute(K key,
1821 >                     BiFun<? super K, ? super V, ? extends V> remappingFunction) {
1822 >        if (key == null || remappingFunction == null)
1823 >            throw new NullPointerException();
1824 >        int h = spread(key.hashCode());
1825 >        V val = null;
1826 >        int delta = 0;
1827 >        int binCount = 0;
1828 >        for (Node<K,V>[] tab = table;;) {
1829 >            Node<K,V> f; int n, i, fh;
1830 >            if (tab == null || (n = tab.length) == 0)
1831 >                tab = initTable();
1832 >            else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1833 >                Node<K,V> r = new ReservationNode<K,V>();
1834 >                synchronized (r) {
1835 >                    if (casTabAt(tab, i, null, r)) {
1836 >                        binCount = 1;
1837 >                        Node<K,V> node = null;
1838 >                        try {
1839 >                            if ((val = remappingFunction.apply(key, null)) != null) {
1840 >                                delta = 1;
1841 >                                node = new Node<K,V>(h, key, val, null);
1842 >                            }
1843 >                        } finally {
1844 >                            setTabAt(tab, i, node);
1845 >                        }
1846 >                    }
1847 >                }
1848 >                if (binCount != 0)
1849 >                    break;
1850 >            }
1851 >            else if ((fh = f.hash) == MOVED)
1852 >                tab = helpTransfer(tab, f);
1853 >            else {
1854 >                synchronized (f) {
1855 >                    if (tabAt(tab, i) == f) {
1856 >                        if (fh >= 0) {
1857 >                            binCount = 1;
1858 >                            for (Node<K,V> e = f, pred = null;; ++binCount) {
1859 >                                K ek;
1860 >                                if (e.hash == h &&
1861 >                                    ((ek = e.key) == key ||
1862 >                                     (ek != null && key.equals(ek)))) {
1863 >                                    val = remappingFunction.apply(key, e.val);
1864 >                                    if (val != null)
1865 >                                        e.val = val;
1866 >                                    else {
1867 >                                        delta = -1;
1868 >                                        Node<K,V> en = e.next;
1869 >                                        if (pred != null)
1870 >                                            pred.next = en;
1871 >                                        else
1872 >                                            setTabAt(tab, i, en);
1873 >                                    }
1874 >                                    break;
1875 >                                }
1876 >                                pred = e;
1877 >                                if ((e = e.next) == null) {
1878 >                                    val = remappingFunction.apply(key, null);
1879 >                                    if (val != null) {
1880 >                                        delta = 1;
1881 >                                        pred.next =
1882 >                                            new Node<K,V>(h, key, val, null);
1883 >                                    }
1884 >                                    break;
1885 >                                }
1886 >                            }
1887 >                        }
1888 >                        else if (f instanceof TreeBin) {
1889 >                            binCount = 1;
1890 >                            TreeBin<K,V> t = (TreeBin<K,V>)f;
1891 >                            TreeNode<K,V> r, p;
1892 >                            if ((r = t.root) != null)
1893 >                                p = r.findTreeNode(h, key, null);
1894 >                            else
1895 >                                p = null;
1896 >                            V pv = (p == null) ? null : p.val;
1897 >                            val = remappingFunction.apply(key, pv);
1898 >                            if (val != null) {
1899 >                                if (p != null)
1900 >                                    p.val = val;
1901 >                                else {
1902 >                                    delta = 1;
1903 >                                    t.putTreeVal(h, key, val);
1904 >                                }
1905 >                            }
1906 >                            else if (p != null) {
1907 >                                delta = -1;
1908 >                                if (t.removeTreeNode(p))
1909 >                                    setTabAt(tab, i, untreeify(t.first));
1910 >                            }
1911 >                        }
1912 >                    }
1913 >                }
1914 >                if (binCount != 0) {
1915 >                    if (binCount >= TREEIFY_THRESHOLD)
1916 >                        treeifyBin(tab, i);
1917 >                    break;
1918 >                }
1919 >            }
1920 >        }
1921 >        if (delta != 0)
1922 >            addCount((long)delta, binCount);
1923 >        return val;
1924 >    }
1925 >
1926 >    /**
1927 >     * If the specified key is not already associated with a
1928 >     * (non-null) value, associates it with the given value.
1929 >     * Otherwise, replaces the value with the results of the given
1930 >     * remapping function, or removes if {@code null}. The entire
1931 >     * method invocation is performed atomically.  Some attempted
1932 >     * update operations on this map by other threads may be blocked
1933 >     * while computation is in progress, so the computation should be
1934 >     * short and simple, and must not attempt to update any other
1935 >     * mappings of this Map.
1936 >     *
1937 >     * @param key key with which the specified value is to be associated
1938 >     * @param value the value to use if absent
1939 >     * @param remappingFunction the function to recompute a value if present
1940 >     * @return the new value associated with the specified key, or null if none
1941 >     * @throws NullPointerException if the specified key or the
1942 >     *         remappingFunction is null
1943 >     * @throws RuntimeException or Error if the remappingFunction does so,
1944 >     *         in which case the mapping is unchanged
1945 >     */
1946 >    public V merge(K key, V value, BiFun<? super V, ? super V, ? extends V> remappingFunction) {
1947 >        if (key == null || value == null || remappingFunction == null)
1948 >            throw new NullPointerException();
1949 >        int h = spread(key.hashCode());
1950 >        V val = null;
1951 >        int delta = 0;
1952 >        int binCount = 0;
1953 >        for (Node<K,V>[] tab = table;;) {
1954 >            Node<K,V> f; int n, i, fh;
1955 >            if (tab == null || (n = tab.length) == 0)
1956 >                tab = initTable();
1957 >            else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1958 >                if (casTabAt(tab, i, null, new Node<K,V>(h, key, value, null))) {
1959 >                    delta = 1;
1960 >                    val = value;
1961 >                    break;
1962 >                }
1963 >            }
1964 >            else if ((fh = f.hash) == MOVED)
1965 >                tab = helpTransfer(tab, f);
1966 >            else {
1967 >                synchronized (f) {
1968 >                    if (tabAt(tab, i) == f) {
1969 >                        if (fh >= 0) {
1970 >                            binCount = 1;
1971 >                            for (Node<K,V> e = f, pred = null;; ++binCount) {
1972 >                                K ek;
1973 >                                if (e.hash == h &&
1974 >                                    ((ek = e.key) == key ||
1975 >                                     (ek != null && key.equals(ek)))) {
1976 >                                    val = remappingFunction.apply(e.val, value);
1977 >                                    if (val != null)
1978 >                                        e.val = val;
1979 >                                    else {
1980 >                                        delta = -1;
1981 >                                        Node<K,V> en = e.next;
1982 >                                        if (pred != null)
1983 >                                            pred.next = en;
1984 >                                        else
1985 >                                            setTabAt(tab, i, en);
1986 >                                    }
1987 >                                    break;
1988 >                                }
1989 >                                pred = e;
1990 >                                if ((e = e.next) == null) {
1991 >                                    delta = 1;
1992 >                                    val = value;
1993 >                                    pred.next =
1994 >                                        new Node<K,V>(h, key, val, null);
1995 >                                    break;
1996 >                                }
1997 >                            }
1998 >                        }
1999 >                        else if (f instanceof TreeBin) {
2000 >                            binCount = 2;
2001 >                            TreeBin<K,V> t = (TreeBin<K,V>)f;
2002 >                            TreeNode<K,V> r = t.root;
2003 >                            TreeNode<K,V> p = (r == null) ? null :
2004 >                                r.findTreeNode(h, key, null);
2005 >                            val = (p == null) ? value :
2006 >                                remappingFunction.apply(p.val, value);
2007 >                            if (val != null) {
2008 >                                if (p != null)
2009 >                                    p.val = val;
2010 >                                else {
2011 >                                    delta = 1;
2012 >                                    t.putTreeVal(h, key, val);
2013 >                                }
2014 >                            }
2015 >                            else if (p != null) {
2016 >                                delta = -1;
2017 >                                if (t.removeTreeNode(p))
2018 >                                    setTabAt(tab, i, untreeify(t.first));
2019 >                            }
2020 >                        }
2021 >                    }
2022 >                }
2023 >                if (binCount != 0) {
2024 >                    if (binCount >= TREEIFY_THRESHOLD)
2025 >                        treeifyBin(tab, i);
2026 >                    break;
2027 >                }
2028 >            }
2029          }
2030 +        if (delta != 0)
2031 +            addCount((long)delta, binCount);
2032 +        return val;
2033 +    }
2034 +
2035 +    // Hashtable legacy methods
2036 +
2037 +    /**
2038 +     * Legacy method testing if some key maps into the specified value
2039 +     * in this table.  This method is identical in functionality to
2040 +     * {@link #containsValue(Object)}, and exists solely to ensure
2041 +     * full compatibility with class {@link java.util.Hashtable},
2042 +     * which supported this method prior to introduction of the
2043 +     * Java Collections framework.
2044 +     *
2045 +     * @param  value a value to search for
2046 +     * @return {@code true} if and only if some key maps to the
2047 +     *         {@code value} argument in this table as
2048 +     *         determined by the {@code equals} method;
2049 +     *         {@code false} otherwise
2050 +     * @throws NullPointerException if the specified value is null
2051 +     */
2052 +    @Deprecated public boolean contains(Object value) {
2053 +        return containsValue(value);
2054 +    }
2055  
2056 <        public ValueIterator<K,V> clone() {
2057 <            if (last != null || (next != null && nextVal == null))
2056 >    /**
2057 >     * Returns an enumeration of the keys in this table.
2058 >     *
2059 >     * @return an enumeration of the keys in this table
2060 >     * @see #keySet()
2061 >     */
2062 >    public Enumeration<K> keys() {
2063 >        Node<K,V>[] t;
2064 >        int f = (t = table) == null ? 0 : t.length;
2065 >        return new KeyIterator<K,V>(t, f, 0, f, this);
2066 >    }
2067 >
2068 >    /**
2069 >     * Returns an enumeration of the values in this table.
2070 >     *
2071 >     * @return an enumeration of the values in this table
2072 >     * @see #values()
2073 >     */
2074 >    public Enumeration<V> elements() {
2075 >        Node<K,V>[] t;
2076 >        int f = (t = table) == null ? 0 : t.length;
2077 >        return new ValueIterator<K,V>(t, f, 0, f, this);
2078 >    }
2079 >
2080 >    // ConcurrentHashMapV8-only methods
2081 >
2082 >    /**
2083 >     * Returns the number of mappings. This method should be used
2084 >     * instead of {@link #size} because a ConcurrentHashMapV8 may
2085 >     * contain more mappings than can be represented as an int. The
2086 >     * value returned is an estimate; the actual count may differ if
2087 >     * there are concurrent insertions or removals.
2088 >     *
2089 >     * @return the number of mappings
2090 >     * @since 1.8
2091 >     */
2092 >    public long mappingCount() {
2093 >        long n = sumCount();
2094 >        return (n < 0L) ? 0L : n; // ignore transient negative values
2095 >    }
2096 >
2097 >    /**
2098 >     * Creates a new {@link Set} backed by a ConcurrentHashMapV8
2099 >     * from the given type to {@code Boolean.TRUE}.
2100 >     *
2101 >     * @return the new set
2102 >     * @since 1.8
2103 >     */
2104 >    public static <K> KeySetView<K,Boolean> newKeySet() {
2105 >        return new KeySetView<K,Boolean>
2106 >            (new ConcurrentHashMapV8<K,Boolean>(), Boolean.TRUE);
2107 >    }
2108 >
2109 >    /**
2110 >     * Creates a new {@link Set} backed by a ConcurrentHashMapV8
2111 >     * from the given type to {@code Boolean.TRUE}.
2112 >     *
2113 >     * @param initialCapacity The implementation performs internal
2114 >     * sizing to accommodate this many elements.
2115 >     * @return the new set
2116 >     * @throws IllegalArgumentException if the initial capacity of
2117 >     * elements is negative
2118 >     * @since 1.8
2119 >     */
2120 >    public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
2121 >        return new KeySetView<K,Boolean>
2122 >            (new ConcurrentHashMapV8<K,Boolean>(initialCapacity), Boolean.TRUE);
2123 >    }
2124 >
2125 >    /**
2126 >     * Returns a {@link Set} view of the keys in this map, using the
2127 >     * given common mapped value for any additions (i.e., {@link
2128 >     * Collection#add} and {@link Collection#addAll(Collection)}).
2129 >     * This is of course only appropriate if it is acceptable to use
2130 >     * the same value for all additions from this view.
2131 >     *
2132 >     * @param mappedValue the mapped value to use for any additions
2133 >     * @return the set view
2134 >     * @throws NullPointerException if the mappedValue is null
2135 >     */
2136 >    public KeySetView<K,V> keySet(V mappedValue) {
2137 >        if (mappedValue == null)
2138 >            throw new NullPointerException();
2139 >        return new KeySetView<K,V>(this, mappedValue);
2140 >    }
2141 >
2142 >    /* ---------------- Special Nodes -------------- */
2143 >
2144 >    /**
2145 >     * A node inserted at head of bins during transfer operations.
2146 >     */
2147 >    static final class ForwardingNode<K,V> extends Node<K,V> {
2148 >        final Node<K,V>[] nextTable;
2149 >        ForwardingNode(Node<K,V>[] tab) {
2150 >            super(MOVED, null, null, null);
2151 >            this.nextTable = tab;
2152 >        }
2153 >
2154 >        Node<K,V> find(int h, Object k) {
2155 >            // loop to avoid arbitrarily deep recursion on forwarding nodes
2156 >            outer: for (Node<K,V>[] tab = nextTable;;) {
2157 >                Node<K,V> e; int n;
2158 >                if (k == null || tab == null || (n = tab.length) == 0 ||
2159 >                    (e = tabAt(tab, (n - 1) & h)) == null)
2160 >                    return null;
2161 >                for (;;) {
2162 >                    int eh; K ek;
2163 >                    if ((eh = e.hash) == h &&
2164 >                        ((ek = e.key) == k || (ek != null && k.equals(ek))))
2165 >                        return e;
2166 >                    if (eh < 0) {
2167 >                        if (e instanceof ForwardingNode) {
2168 >                            tab = ((ForwardingNode<K,V>)e).nextTable;
2169 >                            continue outer;
2170 >                        }
2171 >                        else
2172 >                            return e.find(h, k);
2173 >                    }
2174 >                    if ((e = e.next) == null)
2175 >                        return null;
2176 >                }
2177 >            }
2178 >        }
2179 >    }
2180 >
2181 >    /**
2182 >     * A place-holder node used in computeIfAbsent and compute
2183 >     */
2184 >    static final class ReservationNode<K,V> extends Node<K,V> {
2185 >        ReservationNode() {
2186 >            super(RESERVED, null, null, null);
2187 >        }
2188 >
2189 >        Node<K,V> find(int h, Object k) {
2190 >            return null;
2191 >        }
2192 >    }
2193 >
2194 >    /* ---------------- Table Initialization and Resizing -------------- */
2195 >
2196 >    /**
2197 >     * Initializes table, using the size recorded in sizeCtl.
2198 >     */
2199 >    private final Node<K,V>[] initTable() {
2200 >        Node<K,V>[] tab; int sc;
2201 >        while ((tab = table) == null || tab.length == 0) {
2202 >            if ((sc = sizeCtl) < 0)
2203 >                Thread.yield(); // lost initialization race; just spin
2204 >            else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2205 >                try {
2206 >                    if ((tab = table) == null || tab.length == 0) {
2207 >                        int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
2208 >                        @SuppressWarnings("unchecked")
2209 >                            Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
2210 >                        table = tab = nt;
2211 >                        sc = n - (n >>> 2);
2212 >                    }
2213 >                } finally {
2214 >                    sizeCtl = sc;
2215 >                }
2216 >                break;
2217 >            }
2218 >        }
2219 >        return tab;
2220 >    }
2221 >
2222 >    /**
2223 >     * Adds to count, and if table is too small and not already
2224 >     * resizing, initiates transfer. If already resizing, helps
2225 >     * perform transfer if work is available.  Rechecks occupancy
2226 >     * after a transfer to see if another resize is already needed
2227 >     * because resizings are lagging additions.
2228 >     *
2229 >     * @param x the count to add
2230 >     * @param check if <0, don't check resize, if <= 1 only check if uncontended
2231 >     */
2232 >    private final void addCount(long x, int check) {
2233 >        CounterCell[] as; long b, s;
2234 >        if ((as = counterCells) != null ||
2235 >            !U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
2236 >            CounterHashCode hc; CounterCell a; long v; int m;
2237 >            boolean uncontended = true;
2238 >            if ((hc = threadCounterHashCode.get()) == null ||
2239 >                as == null || (m = as.length - 1) < 0 ||
2240 >                (a = as[m & hc.code]) == null ||
2241 >                !(uncontended =
2242 >                  U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
2243 >                fullAddCount(x, hc, uncontended);
2244 >                return;
2245 >            }
2246 >            if (check <= 1)
2247 >                return;
2248 >            s = sumCount();
2249 >        }
2250 >        if (check >= 0) {
2251 >            Node<K,V>[] tab, nt; int sc;
2252 >            while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
2253 >                   tab.length < MAXIMUM_CAPACITY) {
2254 >                if (sc < 0) {
2255 >                    if (sc == -1 || transferIndex <= transferOrigin ||
2256 >                        (nt = nextTable) == null)
2257 >                        break;
2258 >                    if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2259 >                        transfer(tab, nt);
2260 >                }
2261 >                else if (U.compareAndSwapInt(this, SIZECTL, sc, -2))
2262 >                    transfer(tab, null);
2263 >                s = sumCount();
2264 >            }
2265 >        }
2266 >    }
2267 >
2268 >    /**
2269 >     * Helps transfer if a resize is in progress.
2270 >     */
2271 >    final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) {
2272 >        Node<K,V>[] nextTab; int sc;
2273 >        if ((f instanceof ForwardingNode) &&
2274 >            (nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) {
2275 >            if (nextTab == nextTable && tab == table &&
2276 >                transferIndex > transferOrigin && (sc = sizeCtl) < -1 &&
2277 >                U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2278 >                transfer(tab, nextTab);
2279 >            return nextTab;
2280 >        }
2281 >        return table;
2282 >    }
2283 >
2284 >    /**
2285 >     * Tries to presize table to accommodate the given number of elements.
2286 >     *
2287 >     * @param size number of elements (doesn't need to be perfectly accurate)
2288 >     */
2289 >    private final void tryPresize(int size) {
2290 >        int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
2291 >            tableSizeFor(size + (size >>> 1) + 1);
2292 >        int sc;
2293 >        while ((sc = sizeCtl) >= 0) {
2294 >            Node<K,V>[] tab = table; int n;
2295 >            if (tab == null || (n = tab.length) == 0) {
2296 >                n = (sc > c) ? sc : c;
2297 >                if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2298 >                    try {
2299 >                        if (table == tab) {
2300 >                            @SuppressWarnings("unchecked")
2301 >                                Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
2302 >                            table = nt;
2303 >                            sc = n - (n >>> 2);
2304 >                        }
2305 >                    } finally {
2306 >                        sizeCtl = sc;
2307 >                    }
2308 >                }
2309 >            }
2310 >            else if (c <= sc || n >= MAXIMUM_CAPACITY)
2311 >                break;
2312 >            else if (tab == table &&
2313 >                     U.compareAndSwapInt(this, SIZECTL, sc, -2))
2314 >                transfer(tab, null);
2315 >        }
2316 >    }
2317 >
2318 >    /**
2319 >     * Moves and/or copies the nodes in each bin to new table. See
2320 >     * above for explanation.
2321 >     */
2322 >    private final void transfer(Node<K,V>[] tab, Node<K,V>[] nextTab) {
2323 >        int n = tab.length, stride;
2324 >        if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
2325 >            stride = MIN_TRANSFER_STRIDE; // subdivide range
2326 >        if (nextTab == null) {            // initiating
2327 >            try {
2328 >                @SuppressWarnings("unchecked")
2329 >                    Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n << 1];
2330 >                nextTab = nt;
2331 >            } catch (Throwable ex) {      // try to cope with OOME
2332 >                sizeCtl = Integer.MAX_VALUE;
2333 >                return;
2334 >            }
2335 >            nextTable = nextTab;
2336 >            transferOrigin = n;
2337 >            transferIndex = n;
2338 >            ForwardingNode<K,V> rev = new ForwardingNode<K,V>(tab);
2339 >            for (int k = n; k > 0;) {    // progressively reveal ready slots
2340 >                int nextk = (k > stride) ? k - stride : 0;
2341 >                for (int m = nextk; m < k; ++m)
2342 >                    nextTab[m] = rev;
2343 >                for (int m = n + nextk; m < n + k; ++m)
2344 >                    nextTab[m] = rev;
2345 >                U.putOrderedInt(this, TRANSFERORIGIN, k = nextk);
2346 >            }
2347 >        }
2348 >        int nextn = nextTab.length;
2349 >        ForwardingNode<K,V> fwd = new ForwardingNode<K,V>(nextTab);
2350 >        boolean advance = true;
2351 >        boolean finishing = false; // to ensure sweep before committing nextTab
2352 >        for (int i = 0, bound = 0;;) {
2353 >            int nextIndex, nextBound, fh; Node<K,V> f;
2354 >            while (advance) {
2355 >                if (--i >= bound || finishing)
2356 >                    advance = false;
2357 >                else if ((nextIndex = transferIndex) <= transferOrigin) {
2358 >                    i = -1;
2359 >                    advance = false;
2360 >                }
2361 >                else if (U.compareAndSwapInt
2362 >                         (this, TRANSFERINDEX, nextIndex,
2363 >                          nextBound = (nextIndex > stride ?
2364 >                                       nextIndex - stride : 0))) {
2365 >                    bound = nextBound;
2366 >                    i = nextIndex - 1;
2367 >                    advance = false;
2368 >                }
2369 >            }
2370 >            if (i < 0 || i >= n || i + n >= nextn) {
2371 >                if (finishing) {
2372 >                    nextTable = null;
2373 >                    table = nextTab;
2374 >                    sizeCtl = (n << 1) - (n >>> 1);
2375 >                    return;
2376 >                }
2377 >                for (int sc;;) {
2378 >                    if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) {
2379 >                        if (sc != -1)
2380 >                            return;
2381 >                        finishing = advance = true;
2382 >                        i = n; // recheck before commit
2383 >                        break;
2384 >                    }
2385 >                }
2386 >            }
2387 >            else if ((f = tabAt(tab, i)) == null) {
2388 >                if (casTabAt(tab, i, null, fwd)) {
2389 >                    setTabAt(nextTab, i, null);
2390 >                    setTabAt(nextTab, i + n, null);
2391 >                    advance = true;
2392 >                }
2393 >            }
2394 >            else if ((fh = f.hash) == MOVED)
2395 >                advance = true; // already processed
2396 >            else {
2397 >                synchronized (f) {
2398 >                    if (tabAt(tab, i) == f) {
2399 >                        Node<K,V> ln, hn;
2400 >                        if (fh >= 0) {
2401 >                            int runBit = fh & n;
2402 >                            Node<K,V> lastRun = f;
2403 >                            for (Node<K,V> p = f.next; p != null; p = p.next) {
2404 >                                int b = p.hash & n;
2405 >                                if (b != runBit) {
2406 >                                    runBit = b;
2407 >                                    lastRun = p;
2408 >                                }
2409 >                            }
2410 >                            if (runBit == 0) {
2411 >                                ln = lastRun;
2412 >                                hn = null;
2413 >                            }
2414 >                            else {
2415 >                                hn = lastRun;
2416 >                                ln = null;
2417 >                            }
2418 >                            for (Node<K,V> p = f; p != lastRun; p = p.next) {
2419 >                                int ph = p.hash; K pk = p.key; V pv = p.val;
2420 >                                if ((ph & n) == 0)
2421 >                                    ln = new Node<K,V>(ph, pk, pv, ln);
2422 >                                else
2423 >                                    hn = new Node<K,V>(ph, pk, pv, hn);
2424 >                            }
2425 >                            setTabAt(nextTab, i, ln);
2426 >                            setTabAt(nextTab, i + n, hn);
2427 >                            setTabAt(tab, i, fwd);
2428 >                            advance = true;
2429 >                        }
2430 >                        else if (f instanceof TreeBin) {
2431 >                            TreeBin<K,V> t = (TreeBin<K,V>)f;
2432 >                            TreeNode<K,V> lo = null, loTail = null;
2433 >                            TreeNode<K,V> hi = null, hiTail = null;
2434 >                            int lc = 0, hc = 0;
2435 >                            for (Node<K,V> e = t.first; e != null; e = e.next) {
2436 >                                int h = e.hash;
2437 >                                TreeNode<K,V> p = new TreeNode<K,V>
2438 >                                    (h, e.key, e.val, null, null);
2439 >                                if ((h & n) == 0) {
2440 >                                    if ((p.prev = loTail) == null)
2441 >                                        lo = p;
2442 >                                    else
2443 >                                        loTail.next = p;
2444 >                                    loTail = p;
2445 >                                    ++lc;
2446 >                                }
2447 >                                else {
2448 >                                    if ((p.prev = hiTail) == null)
2449 >                                        hi = p;
2450 >                                    else
2451 >                                        hiTail.next = p;
2452 >                                    hiTail = p;
2453 >                                    ++hc;
2454 >                                }
2455 >                            }
2456 >                            ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) :
2457 >                                (hc != 0) ? new TreeBin<K,V>(lo) : t;
2458 >                            hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
2459 >                                (lc != 0) ? new TreeBin<K,V>(hi) : t;
2460 >                            setTabAt(nextTab, i, ln);
2461 >                            setTabAt(nextTab, i + n, hn);
2462 >                            setTabAt(tab, i, fwd);
2463 >                            advance = true;
2464 >                        }
2465 >                    }
2466 >                }
2467 >            }
2468 >        }
2469 >    }
2470 >
2471 >    /* ---------------- Conversion from/to TreeBins -------------- */
2472 >
2473 >    /**
2474 >     * Replaces all linked nodes in bin at given index unless table is
2475 >     * too small, in which case resizes instead.
2476 >     */
2477 >    private final void treeifyBin(Node<K,V>[] tab, int index) {
2478 >        Node<K,V> b; int n, sc;
2479 >        if (tab != null) {
2480 >            if ((n = tab.length) < MIN_TREEIFY_CAPACITY) {
2481 >                if (tab == table && (sc = sizeCtl) >= 0 &&
2482 >                    U.compareAndSwapInt(this, SIZECTL, sc, -2))
2483 >                    transfer(tab, null);
2484 >            }
2485 >            else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
2486 >                synchronized (b) {
2487 >                    if (tabAt(tab, index) == b) {
2488 >                        TreeNode<K,V> hd = null, tl = null;
2489 >                        for (Node<K,V> e = b; e != null; e = e.next) {
2490 >                            TreeNode<K,V> p =
2491 >                                new TreeNode<K,V>(e.hash, e.key, e.val,
2492 >                                                  null, null);
2493 >                            if ((p.prev = tl) == null)
2494 >                                hd = p;
2495 >                            else
2496 >                                tl.next = p;
2497 >                            tl = p;
2498 >                        }
2499 >                        setTabAt(tab, index, new TreeBin<K,V>(hd));
2500 >                    }
2501 >                }
2502 >            }
2503 >        }
2504 >    }
2505 >
2506 >    /**
2507 >     * Returns a list on non-TreeNodes replacing those in given list.
2508 >     */
2509 >    static <K,V> Node<K,V> untreeify(Node<K,V> b) {
2510 >        Node<K,V> hd = null, tl = null;
2511 >        for (Node<K,V> q = b; q != null; q = q.next) {
2512 >            Node<K,V> p = new Node<K,V>(q.hash, q.key, q.val, null);
2513 >            if (tl == null)
2514 >                hd = p;
2515 >            else
2516 >                tl.next = p;
2517 >            tl = p;
2518 >        }
2519 >        return hd;
2520 >    }
2521 >
2522 >    /* ---------------- TreeNodes -------------- */
2523 >
2524 >    /**
2525 >     * Nodes for use in TreeBins
2526 >     */
2527 >    static final class TreeNode<K,V> extends Node<K,V> {
2528 >        TreeNode<K,V> parent;  // red-black tree links
2529 >        TreeNode<K,V> left;
2530 >        TreeNode<K,V> right;
2531 >        TreeNode<K,V> prev;    // needed to unlink next upon deletion
2532 >        boolean red;
2533 >
2534 >        TreeNode(int hash, K key, V val, Node<K,V> next,
2535 >                 TreeNode<K,V> parent) {
2536 >            super(hash, key, val, next);
2537 >            this.parent = parent;
2538 >        }
2539 >
2540 >        Node<K,V> find(int h, Object k) {
2541 >            return findTreeNode(h, k, null);
2542 >        }
2543 >
2544 >        /**
2545 >         * Returns the TreeNode (or null if not found) for the given key
2546 >         * starting at given root.
2547 >         */
2548 >        final TreeNode<K,V> findTreeNode(int h, Object k, Class<?> kc) {
2549 >            if (k != null) {
2550 >                TreeNode<K,V> p = this;
2551 >                do  {
2552 >                    int ph, dir; K pk; TreeNode<K,V> q;
2553 >                    TreeNode<K,V> pl = p.left, pr = p.right;
2554 >                    if ((ph = p.hash) > h)
2555 >                        p = pl;
2556 >                    else if (ph < h)
2557 >                        p = pr;
2558 >                    else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2559 >                        return p;
2560 >                    else if (pl == null)
2561 >                        p = pr;
2562 >                    else if (pr == null)
2563 >                        p = pl;
2564 >                    else if ((kc != null ||
2565 >                              (kc = comparableClassFor(k)) != null) &&
2566 >                             (dir = compareComparables(kc, k, pk)) != 0)
2567 >                        p = (dir < 0) ? pl : pr;
2568 >                    else if ((q = pr.findTreeNode(h, k, kc)) != null)
2569 >                        return q;
2570 >                    else
2571 >                        p = pl;
2572 >                } while (p != null);
2573 >            }
2574 >            return null;
2575 >        }
2576 >    }
2577 >
2578 >    /* ---------------- TreeBins -------------- */
2579 >
2580 >    /**
2581 >     * TreeNodes used at the heads of bins. TreeBins do not hold user
2582 >     * keys or values, but instead point to list of TreeNodes and
2583 >     * their root. They also maintain a parasitic read-write lock
2584 >     * forcing writers (who hold bin lock) to wait for readers (who do
2585 >     * not) to complete before tree restructuring operations.
2586 >     */
2587 >    static final class TreeBin<K,V> extends Node<K,V> {
2588 >        TreeNode<K,V> root;
2589 >        volatile TreeNode<K,V> first;
2590 >        volatile Thread waiter;
2591 >        volatile int lockState;
2592 >        // values for lockState
2593 >        static final int WRITER = 1; // set while holding write lock
2594 >        static final int WAITER = 2; // set when waiting for write lock
2595 >        static final int READER = 4; // increment value for setting read lock
2596 >
2597 >        /**
2598 >         * Tie-breaking utility for ordering insertions when equal
2599 >         * hashCodes and non-comparable. We don't require a total
2600 >         * order, just a consistent insertion rule to maintain
2601 >         * equivalence across rebalancings. Tie-breaking further than
2602 >         * necessary simplifies testing a bit.
2603 >         */
2604 >        static int tieBreakOrder(Object a, Object b) {
2605 >            int d;
2606 >            if (a == null || b == null ||
2607 >                (d = a.getClass().getName().
2608 >                 compareTo(b.getClass().getName())) == 0)
2609 >                d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
2610 >                     -1 : 1);
2611 >            return d;
2612 >        }
2613 >
2614 >        /**
2615 >         * Creates bin with initial set of nodes headed by b.
2616 >         */
2617 >        TreeBin(TreeNode<K,V> b) {
2618 >            super(TREEBIN, null, null, null);
2619 >            this.first = b;
2620 >            TreeNode<K,V> r = null;
2621 >            for (TreeNode<K,V> x = b, next; x != null; x = next) {
2622 >                next = (TreeNode<K,V>)x.next;
2623 >                x.left = x.right = null;
2624 >                if (r == null) {
2625 >                    x.parent = null;
2626 >                    x.red = false;
2627 >                    r = x;
2628 >                }
2629 >                else {
2630 >                    K k = x.key;
2631 >                    int h = x.hash;
2632 >                    Class<?> kc = null;
2633 >                    for (TreeNode<K,V> p = r;;) {
2634 >                        int dir, ph;
2635 >                        K pk = p.key;
2636 >                        if ((ph = p.hash) > h)
2637 >                            dir = -1;
2638 >                        else if (ph < h)
2639 >                            dir = 1;
2640 >                        else if ((kc == null &&
2641 >                                  (kc = comparableClassFor(k)) == null) ||
2642 >                                 (dir = compareComparables(kc, k, pk)) == 0)
2643 >                            dir = tieBreakOrder(k, pk);
2644 >                            TreeNode<K,V> xp = p;
2645 >                        if ((p = (dir <= 0) ? p.left : p.right) == null) {
2646 >                            x.parent = xp;
2647 >                            if (dir <= 0)
2648 >                                xp.left = x;
2649 >                            else
2650 >                                xp.right = x;
2651 >                            r = balanceInsertion(r, x);
2652 >                            break;
2653 >                        }
2654 >                    }
2655 >                }
2656 >            }
2657 >            this.root = r;
2658 >            assert checkInvariants(root);
2659 >        }
2660 >
2661 >        /**
2662 >         * Acquires write lock for tree restructuring.
2663 >         */
2664 >        private final void lockRoot() {
2665 >            if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER))
2666 >                contendedLock(); // offload to separate method
2667 >        }
2668 >
2669 >        /**
2670 >         * Releases write lock for tree restructuring.
2671 >         */
2672 >        private final void unlockRoot() {
2673 >            lockState = 0;
2674 >        }
2675 >
2676 >        /**
2677 >         * Possibly blocks awaiting root lock.
2678 >         */
2679 >        private final void contendedLock() {
2680 >            boolean waiting = false;
2681 >            for (int s;;) {
2682 >                if (((s = lockState) & WRITER) == 0) {
2683 >                    if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
2684 >                        if (waiting)
2685 >                            waiter = null;
2686 >                        return;
2687 >                    }
2688 >                }
2689 >                else if ((s & WAITER) == 0) {
2690 >                    if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
2691 >                        waiting = true;
2692 >                        waiter = Thread.currentThread();
2693 >                    }
2694 >                }
2695 >                else if (waiting)
2696 >                    LockSupport.park(this);
2697 >            }
2698 >        }
2699 >
2700 >        /**
2701 >         * Returns matching node or null if none. Tries to search
2702 >         * using tree comparisons from root, but continues linear
2703 >         * search when lock not available.
2704 >         */
2705 > final Node<K,V> find(int h, Object k) {
2706 >            if (k != null) {
2707 >                for (Node<K,V> e = first; e != null; e = e.next) {
2708 >                    int s; K ek;
2709 >                    if (((s = lockState) & (WAITER|WRITER)) != 0) {
2710 >                        if (e.hash == h &&
2711 >                            ((ek = e.key) == k || (ek != null && k.equals(ek))))
2712 >                            return e;
2713 >                    }
2714 >                    else if (U.compareAndSwapInt(this, LOCKSTATE, s,
2715 >                                                 s + READER)) {
2716 >                        TreeNode<K,V> r, p;
2717 >                        try {
2718 >                            p = ((r = root) == null ? null :
2719 >                                 r.findTreeNode(h, k, null));
2720 >                        } finally {
2721 >                            Thread w;
2722 >                            int ls;
2723 >                            do {} while (!U.compareAndSwapInt
2724 >                                         (this, LOCKSTATE,
2725 >                                          ls = lockState, ls - READER));
2726 >                            if (ls == (READER|WAITER) && (w = waiter) != null)
2727 >                                LockSupport.unpark(w);
2728 >                        }
2729 >                        return p;
2730 >                    }
2731 >                }
2732 >            }
2733 >            return null;
2734 >        }
2735 >
2736 >        /**
2737 >         * Finds or adds a node.
2738 >         * @return null if added
2739 >         */
2740 >        final TreeNode<K,V> putTreeVal(int h, K k, V v) {
2741 >            Class<?> kc = null;
2742 >            boolean searched = false;
2743 >            for (TreeNode<K,V> p = root;;) {
2744 >                int dir, ph; K pk;
2745 >                if (p == null) {
2746 >                    first = root = new TreeNode<K,V>(h, k, v, null, null);
2747 >                    break;
2748 >                }
2749 >                else if ((ph = p.hash) > h)
2750 >                    dir = -1;
2751 >                else if (ph < h)
2752 >                    dir = 1;
2753 >                else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2754 >                    return p;
2755 >                else if ((kc == null &&
2756 >                          (kc = comparableClassFor(k)) == null) ||
2757 >                         (dir = compareComparables(kc, k, pk)) == 0) {
2758 >                    if (!searched) {
2759 >                        TreeNode<K,V> q, ch;
2760 >                        searched = true;
2761 >                        if (((ch = p.left) != null &&
2762 >                             (q = ch.findTreeNode(h, k, kc)) != null) ||
2763 >                            ((ch = p.right) != null &&
2764 >                             (q = ch.findTreeNode(h, k, kc)) != null))
2765 >                            return q;
2766 >                    }
2767 >                    dir = tieBreakOrder(k, pk);
2768 >                }
2769 >
2770 >                TreeNode<K,V> xp = p;
2771 >                if ((p = (dir <= 0) ? p.left : p.right) == null) {
2772 >                    TreeNode<K,V> x, f = first;
2773 >                    first = x = new TreeNode<K,V>(h, k, v, f, xp);
2774 >                    if (f != null)
2775 >                        f.prev = x;
2776 >                    if (dir <= 0)
2777 >                        xp.left = x;
2778 >                    else
2779 >                        xp.right = x;
2780 >                    if (!xp.red)
2781 >                        x.red = true;
2782 >                    else {
2783 >                        lockRoot();
2784 >                        try {
2785 >                            root = balanceInsertion(root, x);
2786 >                        } finally {
2787 >                            unlockRoot();
2788 >                        }
2789 >                    }
2790 >                    break;
2791 >                }
2792 >            }
2793 >            assert checkInvariants(root);
2794 >            return null;
2795 >        }
2796 >
2797 >        /**
2798 >         * Removes the given node, that must be present before this
2799 >         * call.  This is messier than typical red-black deletion code
2800 >         * because we cannot swap the contents of an interior node
2801 >         * with a leaf successor that is pinned by "next" pointers
2802 >         * that are accessible independently of lock. So instead we
2803 >         * swap the tree linkages.
2804 >         *
2805 >         * @return true if now too small, so should be untreeified
2806 >         */
2807 >        final boolean removeTreeNode(TreeNode<K,V> p) {
2808 >            TreeNode<K,V> next = (TreeNode<K,V>)p.next;
2809 >            TreeNode<K,V> pred = p.prev;  // unlink traversal pointers
2810 >            TreeNode<K,V> r, rl;
2811 >            if (pred == null)
2812 >                first = next;
2813 >            else
2814 >                pred.next = next;
2815 >            if (next != null)
2816 >                next.prev = pred;
2817 >            if (first == null) {
2818 >                root = null;
2819 >                return true;
2820 >            }
2821 >            if ((r = root) == null || r.right == null || // too small
2822 >                (rl = r.left) == null || rl.left == null)
2823 >                return true;
2824 >            lockRoot();
2825 >            try {
2826 >                TreeNode<K,V> replacement;
2827 >                TreeNode<K,V> pl = p.left;
2828 >                TreeNode<K,V> pr = p.right;
2829 >                if (pl != null && pr != null) {
2830 >                    TreeNode<K,V> s = pr, sl;
2831 >                    while ((sl = s.left) != null) // find successor
2832 >                        s = sl;
2833 >                    boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2834 >                    TreeNode<K,V> sr = s.right;
2835 >                    TreeNode<K,V> pp = p.parent;
2836 >                    if (s == pr) { // p was s's direct parent
2837 >                        p.parent = s;
2838 >                        s.right = p;
2839 >                    }
2840 >                    else {
2841 >                        TreeNode<K,V> sp = s.parent;
2842 >                        if ((p.parent = sp) != null) {
2843 >                            if (s == sp.left)
2844 >                                sp.left = p;
2845 >                            else
2846 >                                sp.right = p;
2847 >                        }
2848 >                        if ((s.right = pr) != null)
2849 >                            pr.parent = s;
2850 >                    }
2851 >                    p.left = null;
2852 >                    if ((p.right = sr) != null)
2853 >                        sr.parent = p;
2854 >                    if ((s.left = pl) != null)
2855 >                        pl.parent = s;
2856 >                    if ((s.parent = pp) == null)
2857 >                        r = s;
2858 >                    else if (p == pp.left)
2859 >                        pp.left = s;
2860 >                    else
2861 >                        pp.right = s;
2862 >                    if (sr != null)
2863 >                        replacement = sr;
2864 >                    else
2865 >                        replacement = p;
2866 >                }
2867 >                else if (pl != null)
2868 >                    replacement = pl;
2869 >                else if (pr != null)
2870 >                    replacement = pr;
2871 >                else
2872 >                    replacement = p;
2873 >                if (replacement != p) {
2874 >                    TreeNode<K,V> pp = replacement.parent = p.parent;
2875 >                    if (pp == null)
2876 >                        r = replacement;
2877 >                    else if (p == pp.left)
2878 >                        pp.left = replacement;
2879 >                    else
2880 >                        pp.right = replacement;
2881 >                    p.left = p.right = p.parent = null;
2882 >                }
2883 >
2884 >                root = (p.red) ? r : balanceDeletion(r, replacement);
2885 >
2886 >                if (p == replacement) {  // detach pointers
2887 >                    TreeNode<K,V> pp;
2888 >                    if ((pp = p.parent) != null) {
2889 >                        if (p == pp.left)
2890 >                            pp.left = null;
2891 >                        else if (p == pp.right)
2892 >                            pp.right = null;
2893 >                        p.parent = null;
2894 >                    }
2895 >                }
2896 >            } finally {
2897 >                unlockRoot();
2898 >            }
2899 >            assert checkInvariants(root);
2900 >            return false;
2901 >        }
2902 >
2903 >        /* ------------------------------------------------------------ */
2904 >        // Red-black tree methods, all adapted from CLR
2905 >
2906 >        static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2907 >                                              TreeNode<K,V> p) {
2908 >            TreeNode<K,V> r, pp, rl;
2909 >            if (p != null && (r = p.right) != null) {
2910 >                if ((rl = p.right = r.left) != null)
2911 >                    rl.parent = p;
2912 >                if ((pp = r.parent = p.parent) == null)
2913 >                    (root = r).red = false;
2914 >                else if (pp.left == p)
2915 >                    pp.left = r;
2916 >                else
2917 >                    pp.right = r;
2918 >                r.left = p;
2919 >                p.parent = r;
2920 >            }
2921 >            return root;
2922 >        }
2923 >
2924 >        static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2925 >                                               TreeNode<K,V> p) {
2926 >            TreeNode<K,V> l, pp, lr;
2927 >            if (p != null && (l = p.left) != null) {
2928 >                if ((lr = p.left = l.right) != null)
2929 >                    lr.parent = p;
2930 >                if ((pp = l.parent = p.parent) == null)
2931 >                    (root = l).red = false;
2932 >                else if (pp.right == p)
2933 >                    pp.right = l;
2934 >                else
2935 >                    pp.left = l;
2936 >                l.right = p;
2937 >                p.parent = l;
2938 >            }
2939 >            return root;
2940 >        }
2941 >
2942 >        static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2943 >                                                    TreeNode<K,V> x) {
2944 >            x.red = true;
2945 >            for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2946 >                if ((xp = x.parent) == null) {
2947 >                    x.red = false;
2948 >                    return x;
2949 >                }
2950 >                else if (!xp.red || (xpp = xp.parent) == null)
2951 >                    return root;
2952 >                if (xp == (xppl = xpp.left)) {
2953 >                    if ((xppr = xpp.right) != null && xppr.red) {
2954 >                        xppr.red = false;
2955 >                        xp.red = false;
2956 >                        xpp.red = true;
2957 >                        x = xpp;
2958 >                    }
2959 >                    else {
2960 >                        if (x == xp.right) {
2961 >                            root = rotateLeft(root, x = xp);
2962 >                            xpp = (xp = x.parent) == null ? null : xp.parent;
2963 >                        }
2964 >                        if (xp != null) {
2965 >                            xp.red = false;
2966 >                            if (xpp != null) {
2967 >                                xpp.red = true;
2968 >                                root = rotateRight(root, xpp);
2969 >                            }
2970 >                        }
2971 >                    }
2972 >                }
2973 >                else {
2974 >                    if (xppl != null && xppl.red) {
2975 >                        xppl.red = false;
2976 >                        xp.red = false;
2977 >                        xpp.red = true;
2978 >                        x = xpp;
2979 >                    }
2980 >                    else {
2981 >                        if (x == xp.left) {
2982 >                            root = rotateRight(root, x = xp);
2983 >                            xpp = (xp = x.parent) == null ? null : xp.parent;
2984 >                        }
2985 >                        if (xp != null) {
2986 >                            xp.red = false;
2987 >                            if (xpp != null) {
2988 >                                xpp.red = true;
2989 >                                root = rotateLeft(root, xpp);
2990 >                            }
2991 >                        }
2992 >                    }
2993 >                }
2994 >            }
2995 >        }
2996 >
2997 >        static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2998 >                                                   TreeNode<K,V> x) {
2999 >            for (TreeNode<K,V> xp, xpl, xpr;;)  {
3000 >                if (x == null || x == root)
3001 >                    return root;
3002 >                else if ((xp = x.parent) == null) {
3003 >                    x.red = false;
3004 >                    return x;
3005 >                }
3006 >                else if (x.red) {
3007 >                    x.red = false;
3008 >                    return root;
3009 >                }
3010 >                else if ((xpl = xp.left) == x) {
3011 >                    if ((xpr = xp.right) != null && xpr.red) {
3012 >                        xpr.red = false;
3013 >                        xp.red = true;
3014 >                        root = rotateLeft(root, xp);
3015 >                        xpr = (xp = x.parent) == null ? null : xp.right;
3016 >                    }
3017 >                    if (xpr == null)
3018 >                        x = xp;
3019 >                    else {
3020 >                        TreeNode<K,V> sl = xpr.left, sr = xpr.right;
3021 >                        if ((sr == null || !sr.red) &&
3022 >                            (sl == null || !sl.red)) {
3023 >                            xpr.red = true;
3024 >                            x = xp;
3025 >                        }
3026 >                        else {
3027 >                            if (sr == null || !sr.red) {
3028 >                                if (sl != null)
3029 >                                    sl.red = false;
3030 >                                xpr.red = true;
3031 >                                root = rotateRight(root, xpr);
3032 >                                xpr = (xp = x.parent) == null ?
3033 >                                    null : xp.right;
3034 >                            }
3035 >                            if (xpr != null) {
3036 >                                xpr.red = (xp == null) ? false : xp.red;
3037 >                                if ((sr = xpr.right) != null)
3038 >                                    sr.red = false;
3039 >                            }
3040 >                            if (xp != null) {
3041 >                                xp.red = false;
3042 >                                root = rotateLeft(root, xp);
3043 >                            }
3044 >                            x = root;
3045 >                        }
3046 >                    }
3047 >                }
3048 >                else { // symmetric
3049 >                    if (xpl != null && xpl.red) {
3050 >                        xpl.red = false;
3051 >                        xp.red = true;
3052 >                        root = rotateRight(root, xp);
3053 >                        xpl = (xp = x.parent) == null ? null : xp.left;
3054 >                    }
3055 >                    if (xpl == null)
3056 >                        x = xp;
3057 >                    else {
3058 >                        TreeNode<K,V> sl = xpl.left, sr = xpl.right;
3059 >                        if ((sl == null || !sl.red) &&
3060 >                            (sr == null || !sr.red)) {
3061 >                            xpl.red = true;
3062 >                            x = xp;
3063 >                        }
3064 >                        else {
3065 >                            if (sl == null || !sl.red) {
3066 >                                if (sr != null)
3067 >                                    sr.red = false;
3068 >                                xpl.red = true;
3069 >                                root = rotateLeft(root, xpl);
3070 >                                xpl = (xp = x.parent) == null ?
3071 >                                    null : xp.left;
3072 >                            }
3073 >                            if (xpl != null) {
3074 >                                xpl.red = (xp == null) ? false : xp.red;
3075 >                                if ((sl = xpl.left) != null)
3076 >                                    sl.red = false;
3077 >                            }
3078 >                            if (xp != null) {
3079 >                                xp.red = false;
3080 >                                root = rotateRight(root, xp);
3081 >                            }
3082 >                            x = root;
3083 >                        }
3084 >                    }
3085 >                }
3086 >            }
3087 >        }
3088 >
3089 >        /**
3090 >         * Recursive invariant check
3091 >         */
3092 >        static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
3093 >            TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
3094 >                tb = t.prev, tn = (TreeNode<K,V>)t.next;
3095 >            if (tb != null && tb.next != t)
3096 >                return false;
3097 >            if (tn != null && tn.prev != t)
3098 >                return false;
3099 >            if (tp != null && t != tp.left && t != tp.right)
3100 >                return false;
3101 >            if (tl != null && (tl.parent != t || tl.hash > t.hash))
3102 >                return false;
3103 >            if (tr != null && (tr.parent != t || tr.hash < t.hash))
3104 >                return false;
3105 >            if (t.red && tl != null && tl.red && tr != null && tr.red)
3106 >                return false;
3107 >            if (tl != null && !checkInvariants(tl))
3108 >                return false;
3109 >            if (tr != null && !checkInvariants(tr))
3110 >                return false;
3111 >            return true;
3112 >        }
3113 >
3114 >        private static final sun.misc.Unsafe U;
3115 >        private static final long LOCKSTATE;
3116 >        static {
3117 >            try {
3118 >                U = getUnsafe();
3119 >                Class<?> k = TreeBin.class;
3120 >                LOCKSTATE = U.objectFieldOffset
3121 >                    (k.getDeclaredField("lockState"));
3122 >            } catch (Exception e) {
3123 >                throw new Error(e);
3124 >            }
3125 >        }
3126 >    }
3127 >
3128 >    /* ----------------Table Traversal -------------- */
3129 >
3130 >    /**
3131 >     * Encapsulates traversal for methods such as containsValue; also
3132 >     * serves as a base class for other iterators and spliterators.
3133 >     *
3134 >     * Method advance visits once each still-valid node that was
3135 >     * reachable upon iterator construction. It might miss some that
3136 >     * were added to a bin after the bin was visited, which is OK wrt
3137 >     * consistency guarantees. Maintaining this property in the face
3138 >     * of possible ongoing resizes requires a fair amount of
3139 >     * bookkeeping state that is difficult to optimize away amidst
3140 >     * volatile accesses.  Even so, traversal maintains reasonable
3141 >     * throughput.
3142 >     *
3143 >     * Normally, iteration proceeds bin-by-bin traversing lists.
3144 >     * However, if the table has been resized, then all future steps
3145 >     * must traverse both the bin at the current index as well as at
3146 >     * (index + baseSize); and so on for further resizings. To
3147 >     * paranoically cope with potential sharing by users of iterators
3148 >     * across threads, iteration terminates if a bounds checks fails
3149 >     * for a table read.
3150 >     */
3151 >    static class Traverser<K,V> {
3152 >        Node<K,V>[] tab;        // current table; updated if resized
3153 >        Node<K,V> next;         // the next entry to use
3154 >        int index;              // index of bin to use next
3155 >        int baseIndex;          // current index of initial table
3156 >        int baseLimit;          // index bound for initial table
3157 >        final int baseSize;     // initial table size
3158 >
3159 >        Traverser(Node<K,V>[] tab, int size, int index, int limit) {
3160 >            this.tab = tab;
3161 >            this.baseSize = size;
3162 >            this.baseIndex = this.index = index;
3163 >            this.baseLimit = limit;
3164 >            this.next = null;
3165 >        }
3166 >
3167 >        /**
3168 >         * Advances if possible, returning next valid node, or null if none.
3169 >         */
3170 >        final Node<K,V> advance() {
3171 >            Node<K,V> e;
3172 >            if ((e = next) != null)
3173 >                e = e.next;
3174 >            for (;;) {
3175 >                Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
3176 >                if (e != null)
3177 >                    return next = e;
3178 >                if (baseIndex >= baseLimit || (t = tab) == null ||
3179 >                    (n = t.length) <= (i = index) || i < 0)
3180 >                    return next = null;
3181 >                if ((e = tabAt(t, index)) != null && e.hash < 0) {
3182 >                    if (e instanceof ForwardingNode) {
3183 >                        tab = ((ForwardingNode<K,V>)e).nextTable;
3184 >                        e = null;
3185 >                        continue;
3186 >                    }
3187 >                    else if (e instanceof TreeBin)
3188 >                        e = ((TreeBin<K,V>)e).first;
3189 >                    else
3190 >                        e = null;
3191 >                }
3192 >                if ((index += baseSize) >= n)
3193 >                    index = ++baseIndex;    // visit upper slots if present
3194 >            }
3195 >        }
3196 >    }
3197 >
3198 >    /**
3199 >     * Base of key, value, and entry Iterators. Adds fields to
3200 >     * Traverser to support iterator.remove.
3201 >     */
3202 >    static class BaseIterator<K,V> extends Traverser<K,V> {
3203 >        final ConcurrentHashMapV8<K,V> map;
3204 >        Node<K,V> lastReturned;
3205 >        BaseIterator(Node<K,V>[] tab, int size, int index, int limit,
3206 >                    ConcurrentHashMapV8<K,V> map) {
3207 >            super(tab, size, index, limit);
3208 >            this.map = map;
3209 >            advance();
3210 >        }
3211 >
3212 >        public final boolean hasNext() { return next != null; }
3213 >        public final boolean hasMoreElements() { return next != null; }
3214 >
3215 >        public final void remove() {
3216 >            Node<K,V> p;
3217 >            if ((p = lastReturned) == null)
3218                  throw new IllegalStateException();
3219 <            return new ValueIterator<K,V>(this, false);
3219 >            lastReturned = null;
3220 >            map.replaceNode(p.key, null, null);
3221 >        }
3222 >    }
3223 >
3224 >    static final class KeyIterator<K,V> extends BaseIterator<K,V>
3225 >        implements Iterator<K>, Enumeration<K> {
3226 >        KeyIterator(Node<K,V>[] tab, int index, int size, int limit,
3227 >                    ConcurrentHashMapV8<K,V> map) {
3228 >            super(tab, index, size, limit, map);
3229          }
3230  
3231 <        @SuppressWarnings("unchecked")
3232 <        public final V next() {
3233 <            Object v;
2878 <            if ((v = nextVal) == null && (v = advance()) == null)
3231 >        public final K next() {
3232 >            Node<K,V> p;
3233 >            if ((p = next) == null)
3234                  throw new NoSuchElementException();
3235 <            nextVal = null;
3236 <            return (V) v;
3235 >            K k = p.key;
3236 >            lastReturned = p;
3237 >            advance();
3238 >            return k;
3239          }
3240  
3241 <        public final V nextElement() { return next(); }
3241 >        public final K nextElement() { return next(); }
3242      }
3243  
3244 <    static final class EntryIterator<K,V> extends InternalIterator<K,V>
3245 <        implements Spliterator<Map.Entry<K,V>> {
3246 <        EntryIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
3247 <        EntryIterator(InternalIterator<K,V> it, boolean split) {
3248 <            super(it, split);
3244 >    static final class ValueIterator<K,V> extends BaseIterator<K,V>
3245 >        implements Iterator<V>, Enumeration<V> {
3246 >        ValueIterator(Node<K,V>[] tab, int index, int size, int limit,
3247 >                      ConcurrentHashMapV8<K,V> map) {
3248 >            super(tab, index, size, limit, map);
3249          }
3250 <        public EntryIterator<K,V> split() {
3251 <            if (last != null || (next != null && nextVal == null))
3252 <                throw new IllegalStateException();
3253 <            return new EntryIterator<K,V>(this, true);
3250 >
3251 >        public final V next() {
3252 >            Node<K,V> p;
3253 >            if ((p = next) == null)
3254 >                throw new NoSuchElementException();
3255 >            V v = p.val;
3256 >            lastReturned = p;
3257 >            advance();
3258 >            return v;
3259          }
3260 <        public EntryIterator<K,V> clone() {
3261 <            if (last != null || (next != null && nextVal == null))
3262 <                throw new IllegalStateException();
3263 <            return new EntryIterator<K,V>(this, false);
3260 >
3261 >        public final V nextElement() { return next(); }
3262 >    }
3263 >
3264 >    static final class EntryIterator<K,V> extends BaseIterator<K,V>
3265 >        implements Iterator<Map.Entry<K,V>> {
3266 >        EntryIterator(Node<K,V>[] tab, int index, int size, int limit,
3267 >                      ConcurrentHashMapV8<K,V> map) {
3268 >            super(tab, index, size, limit, map);
3269          }
3270  
2904        @SuppressWarnings("unchecked")
3271          public final Map.Entry<K,V> next() {
3272 <            Object v;
3273 <            if ((v = nextVal) == null && (v = advance()) == null)
3272 >            Node<K,V> p;
3273 >            if ((p = next) == null)
3274                  throw new NoSuchElementException();
3275 <            Object k = nextKey;
3276 <            nextVal = null;
3277 <            return new MapEntry<K,V>((K)k, (V)v, map);
3275 >            K k = p.key;
3276 >            V v = p.val;
3277 >            lastReturned = p;
3278 >            advance();
3279 >            return new MapEntry<K,V>(k, v, map);
3280          }
3281      }
3282  
3283      /**
3284 <     * Exported Entry for iterators
3284 >     * Exported Entry for EntryIterator
3285       */
3286 <    static final class MapEntry<K,V> implements Map.Entry<K, V> {
3286 >    static final class MapEntry<K,V> implements Map.Entry<K,V> {
3287          final K key; // non-null
3288          V val;       // non-null
3289 <        final ConcurrentHashMapV8<K, V> map;
3290 <        MapEntry(K key, V val, ConcurrentHashMapV8<K, V> map) {
3289 >        final ConcurrentHashMapV8<K,V> map;
3290 >        MapEntry(K key, V val, ConcurrentHashMapV8<K,V> map) {
3291              this.key = key;
3292              this.val = val;
3293              this.map = map;
3294          }
3295 <        public final K getKey()       { return key; }
3296 <        public final V getValue()     { return val; }
3297 <        public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
3298 <        public final String toString(){ return key + "=" + val; }
3295 >        public K getKey()        { return key; }
3296 >        public V getValue()      { return val; }
3297 >        public int hashCode()    { return key.hashCode() ^ val.hashCode(); }
3298 >        public String toString() { return key + "=" + val; }
3299  
3300 <        public final boolean equals(Object o) {
3300 >        public boolean equals(Object o) {
3301              Object k, v; Map.Entry<?,?> e;
3302              return ((o instanceof Map.Entry) &&
3303                      (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
# Line 2940 | Line 3308 | public class ConcurrentHashMapV8<K, V>
3308  
3309          /**
3310           * Sets our entry's value and writes through to the map. The
3311 <         * value to return is somewhat arbitrary here. Since a we do
3312 <         * not necessarily track asynchronous changes, the most recent
3311 >         * value to return is somewhat arbitrary here. Since we do not
3312 >         * necessarily track asynchronous changes, the most recent
3313           * "previous" value could be different from what we return (or
3314 <         * could even have been removed in which case the put will
3314 >         * could even have been removed, in which case the put will
3315           * re-establish). We do not and cannot guarantee more.
3316           */
3317 <        public final V setValue(V value) {
3317 >        public V setValue(V value) {
3318              if (value == null) throw new NullPointerException();
3319              V v = val;
3320              val = value;
# Line 2955 | Line 3323 | public class ConcurrentHashMapV8<K, V>
3323          }
3324      }
3325  
3326 +    static final class KeySpliterator<K,V> extends Traverser<K,V>
3327 +        implements ConcurrentHashMapSpliterator<K> {
3328 +        long est;               // size estimate
3329 +        KeySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3330 +                       long est) {
3331 +            super(tab, size, index, limit);
3332 +            this.est = est;
3333 +        }
3334 +
3335 +        public ConcurrentHashMapSpliterator<K> trySplit() {
3336 +            int i, f, h;
3337 +            return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3338 +                new KeySpliterator<K,V>(tab, baseSize, baseLimit = h,
3339 +                                        f, est >>>= 1);
3340 +        }
3341 +
3342 +        public void forEachRemaining(Action<? super K> action) {
3343 +            if (action == null) throw new NullPointerException();
3344 +            for (Node<K,V> p; (p = advance()) != null;)
3345 +                action.apply(p.key);
3346 +        }
3347 +
3348 +        public boolean tryAdvance(Action<? super K> action) {
3349 +            if (action == null) throw new NullPointerException();
3350 +            Node<K,V> p;
3351 +            if ((p = advance()) == null)
3352 +                return false;
3353 +            action.apply(p.key);
3354 +            return true;
3355 +        }
3356 +
3357 +        public long estimateSize() { return est; }
3358 +
3359 +    }
3360 +
3361 +    static final class ValueSpliterator<K,V> extends Traverser<K,V>
3362 +        implements ConcurrentHashMapSpliterator<V> {
3363 +        long est;               // size estimate
3364 +        ValueSpliterator(Node<K,V>[] tab, int size, int index, int limit,
3365 +                         long est) {
3366 +            super(tab, size, index, limit);
3367 +            this.est = est;
3368 +        }
3369 +
3370 +        public ConcurrentHashMapSpliterator<V> trySplit() {
3371 +            int i, f, h;
3372 +            return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3373 +                new ValueSpliterator<K,V>(tab, baseSize, baseLimit = h,
3374 +                                          f, est >>>= 1);
3375 +        }
3376 +
3377 +        public void forEachRemaining(Action<? super V> action) {
3378 +            if (action == null) throw new NullPointerException();
3379 +            for (Node<K,V> p; (p = advance()) != null;)
3380 +                action.apply(p.val);
3381 +        }
3382 +
3383 +        public boolean tryAdvance(Action<? super V> action) {
3384 +            if (action == null) throw new NullPointerException();
3385 +            Node<K,V> p;
3386 +            if ((p = advance()) == null)
3387 +                return false;
3388 +            action.apply(p.val);
3389 +            return true;
3390 +        }
3391 +
3392 +        public long estimateSize() { return est; }
3393 +
3394 +    }
3395 +
3396 +    static final class EntrySpliterator<K,V> extends Traverser<K,V>
3397 +        implements ConcurrentHashMapSpliterator<Map.Entry<K,V>> {
3398 +        final ConcurrentHashMapV8<K,V> map; // To export MapEntry
3399 +        long est;               // size estimate
3400 +        EntrySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3401 +                         long est, ConcurrentHashMapV8<K,V> map) {
3402 +            super(tab, size, index, limit);
3403 +            this.map = map;
3404 +            this.est = est;
3405 +        }
3406 +
3407 +        public ConcurrentHashMapSpliterator<Map.Entry<K,V>> trySplit() {
3408 +            int i, f, h;
3409 +            return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3410 +                new EntrySpliterator<K,V>(tab, baseSize, baseLimit = h,
3411 +                                          f, est >>>= 1, map);
3412 +        }
3413 +
3414 +        public void forEachRemaining(Action<? super Map.Entry<K,V>> action) {
3415 +            if (action == null) throw new NullPointerException();
3416 +            for (Node<K,V> p; (p = advance()) != null; )
3417 +                action.apply(new MapEntry<K,V>(p.key, p.val, map));
3418 +        }
3419 +
3420 +        public boolean tryAdvance(Action<? super Map.Entry<K,V>> action) {
3421 +            if (action == null) throw new NullPointerException();
3422 +            Node<K,V> p;
3423 +            if ((p = advance()) == null)
3424 +                return false;
3425 +            action.apply(new MapEntry<K,V>(p.key, p.val, map));
3426 +            return true;
3427 +        }
3428 +
3429 +        public long estimateSize() { return est; }
3430 +
3431 +    }
3432 +
3433 +    // Parallel bulk operations
3434 +
3435 +    /**
3436 +     * Computes initial batch value for bulk tasks. The returned value
3437 +     * is approximately exp2 of the number of times (minus one) to
3438 +     * split task by two before executing leaf action. This value is
3439 +     * faster to compute and more convenient to use as a guide to
3440 +     * splitting than is the depth, since it is used while dividing by
3441 +     * two anyway.
3442 +     */
3443 +    final int batchFor(long b) {
3444 +        long n;
3445 +        if (b == Long.MAX_VALUE || (n = sumCount()) <= 1L || n < b)
3446 +            return 0;
3447 +        int sp = ForkJoinPool.getCommonPoolParallelism() << 2; // slack of 4
3448 +        return (b <= 0L || (n /= b) >= sp) ? sp : (int)n;
3449 +    }
3450 +
3451 +    /**
3452 +     * Performs the given action for each (key, value).
3453 +     *
3454 +     * @param parallelismThreshold the (estimated) number of elements
3455 +     * needed for this operation to be executed in parallel
3456 +     * @param action the action
3457 +     * @since 1.8
3458 +     */
3459 +    public void forEach(long parallelismThreshold,
3460 +                        BiAction<? super K,? super V> action) {
3461 +        if (action == null) throw new NullPointerException();
3462 +        new ForEachMappingTask<K,V>
3463 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3464 +             action).invoke();
3465 +    }
3466 +
3467 +    /**
3468 +     * Performs the given action for each non-null transformation
3469 +     * of each (key, value).
3470 +     *
3471 +     * @param parallelismThreshold the (estimated) number of elements
3472 +     * needed for this operation to be executed in parallel
3473 +     * @param transformer a function returning the transformation
3474 +     * for an element, or null if there is no transformation (in
3475 +     * which case the action is not applied)
3476 +     * @param action the action
3477 +     * @since 1.8
3478 +     */
3479 +    public <U> void forEach(long parallelismThreshold,
3480 +                            BiFun<? super K, ? super V, ? extends U> transformer,
3481 +                            Action<? super U> action) {
3482 +        if (transformer == null || action == null)
3483 +            throw new NullPointerException();
3484 +        new ForEachTransformedMappingTask<K,V,U>
3485 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3486 +             transformer, action).invoke();
3487 +    }
3488 +
3489 +    /**
3490 +     * Returns a non-null result from applying the given search
3491 +     * function on each (key, value), or null if none.  Upon
3492 +     * success, further element processing is suppressed and the
3493 +     * results of any other parallel invocations of the search
3494 +     * function are ignored.
3495 +     *
3496 +     * @param parallelismThreshold the (estimated) number of elements
3497 +     * needed for this operation to be executed in parallel
3498 +     * @param searchFunction a function returning a non-null
3499 +     * result on success, else null
3500 +     * @return a non-null result from applying the given search
3501 +     * function on each (key, value), or null if none
3502 +     * @since 1.8
3503 +     */
3504 +    public <U> U search(long parallelismThreshold,
3505 +                        BiFun<? super K, ? super V, ? extends U> searchFunction) {
3506 +        if (searchFunction == null) throw new NullPointerException();
3507 +        return new SearchMappingsTask<K,V,U>
3508 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3509 +             searchFunction, new AtomicReference<U>()).invoke();
3510 +    }
3511 +
3512 +    /**
3513 +     * Returns the result of accumulating the given transformation
3514 +     * of all (key, value) pairs using the given reducer to
3515 +     * combine values, or null if none.
3516 +     *
3517 +     * @param parallelismThreshold the (estimated) number of elements
3518 +     * needed for this operation to be executed in parallel
3519 +     * @param transformer a function returning the transformation
3520 +     * for an element, or null if there is no transformation (in
3521 +     * which case it is not combined)
3522 +     * @param reducer a commutative associative combining function
3523 +     * @return the result of accumulating the given transformation
3524 +     * of all (key, value) pairs
3525 +     * @since 1.8
3526 +     */
3527 +    public <U> U reduce(long parallelismThreshold,
3528 +                        BiFun<? super K, ? super V, ? extends U> transformer,
3529 +                        BiFun<? super U, ? super U, ? extends U> reducer) {
3530 +        if (transformer == null || reducer == null)
3531 +            throw new NullPointerException();
3532 +        return new MapReduceMappingsTask<K,V,U>
3533 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3534 +             null, transformer, reducer).invoke();
3535 +    }
3536 +
3537 +    /**
3538 +     * Returns the result of accumulating the given transformation
3539 +     * of all (key, value) pairs using the given reducer to
3540 +     * combine values, and the given basis as an identity value.
3541 +     *
3542 +     * @param parallelismThreshold the (estimated) number of elements
3543 +     * needed for this operation to be executed in parallel
3544 +     * @param transformer a function returning the transformation
3545 +     * for an element
3546 +     * @param basis the identity (initial default value) for the reduction
3547 +     * @param reducer a commutative associative combining function
3548 +     * @return the result of accumulating the given transformation
3549 +     * of all (key, value) pairs
3550 +     * @since 1.8
3551 +     */
3552 +    public double reduceToDouble(long parallelismThreshold,
3553 +                                 ObjectByObjectToDouble<? super K, ? super V> transformer,
3554 +                                 double basis,
3555 +                                 DoubleByDoubleToDouble reducer) {
3556 +        if (transformer == null || reducer == null)
3557 +            throw new NullPointerException();
3558 +        return new MapReduceMappingsToDoubleTask<K,V>
3559 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3560 +             null, transformer, basis, reducer).invoke();
3561 +    }
3562 +
3563 +    /**
3564 +     * Returns the result of accumulating the given transformation
3565 +     * of all (key, value) pairs using the given reducer to
3566 +     * combine values, and the given basis as an identity value.
3567 +     *
3568 +     * @param parallelismThreshold the (estimated) number of elements
3569 +     * needed for this operation to be executed in parallel
3570 +     * @param transformer a function returning the transformation
3571 +     * for an element
3572 +     * @param basis the identity (initial default value) for the reduction
3573 +     * @param reducer a commutative associative combining function
3574 +     * @return the result of accumulating the given transformation
3575 +     * of all (key, value) pairs
3576 +     * @since 1.8
3577 +     */
3578 +    public long reduceToLong(long parallelismThreshold,
3579 +                             ObjectByObjectToLong<? super K, ? super V> transformer,
3580 +                             long basis,
3581 +                             LongByLongToLong reducer) {
3582 +        if (transformer == null || reducer == null)
3583 +            throw new NullPointerException();
3584 +        return new MapReduceMappingsToLongTask<K,V>
3585 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3586 +             null, transformer, basis, reducer).invoke();
3587 +    }
3588 +
3589 +    /**
3590 +     * Returns the result of accumulating the given transformation
3591 +     * of all (key, value) pairs using the given reducer to
3592 +     * combine values, and the given basis as an identity value.
3593 +     *
3594 +     * @param parallelismThreshold the (estimated) number of elements
3595 +     * needed for this operation to be executed in parallel
3596 +     * @param transformer a function returning the transformation
3597 +     * for an element
3598 +     * @param basis the identity (initial default value) for the reduction
3599 +     * @param reducer a commutative associative combining function
3600 +     * @return the result of accumulating the given transformation
3601 +     * of all (key, value) pairs
3602 +     * @since 1.8
3603 +     */
3604 +    public int reduceToInt(long parallelismThreshold,
3605 +                           ObjectByObjectToInt<? super K, ? super V> transformer,
3606 +                           int basis,
3607 +                           IntByIntToInt reducer) {
3608 +        if (transformer == null || reducer == null)
3609 +            throw new NullPointerException();
3610 +        return new MapReduceMappingsToIntTask<K,V>
3611 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3612 +             null, transformer, basis, reducer).invoke();
3613 +    }
3614 +
3615 +    /**
3616 +     * Performs the given action for each key.
3617 +     *
3618 +     * @param parallelismThreshold the (estimated) number of elements
3619 +     * needed for this operation to be executed in parallel
3620 +     * @param action the action
3621 +     * @since 1.8
3622 +     */
3623 +    public void forEachKey(long parallelismThreshold,
3624 +                           Action<? super K> action) {
3625 +        if (action == null) throw new NullPointerException();
3626 +        new ForEachKeyTask<K,V>
3627 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3628 +             action).invoke();
3629 +    }
3630 +
3631 +    /**
3632 +     * Performs the given action for each non-null transformation
3633 +     * of each key.
3634 +     *
3635 +     * @param parallelismThreshold the (estimated) number of elements
3636 +     * needed for this operation to be executed in parallel
3637 +     * @param transformer a function returning the transformation
3638 +     * for an element, or null if there is no transformation (in
3639 +     * which case the action is not applied)
3640 +     * @param action the action
3641 +     * @since 1.8
3642 +     */
3643 +    public <U> void forEachKey(long parallelismThreshold,
3644 +                               Fun<? super K, ? extends U> transformer,
3645 +                               Action<? super U> action) {
3646 +        if (transformer == null || action == null)
3647 +            throw new NullPointerException();
3648 +        new ForEachTransformedKeyTask<K,V,U>
3649 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3650 +             transformer, action).invoke();
3651 +    }
3652 +
3653 +    /**
3654 +     * Returns a non-null result from applying the given search
3655 +     * function on each key, or null if none. Upon success,
3656 +     * further element processing is suppressed and the results of
3657 +     * any other parallel invocations of the search function are
3658 +     * ignored.
3659 +     *
3660 +     * @param parallelismThreshold the (estimated) number of elements
3661 +     * needed for this operation to be executed in parallel
3662 +     * @param searchFunction a function returning a non-null
3663 +     * result on success, else null
3664 +     * @return a non-null result from applying the given search
3665 +     * function on each key, or null if none
3666 +     * @since 1.8
3667 +     */
3668 +    public <U> U searchKeys(long parallelismThreshold,
3669 +                            Fun<? super K, ? extends U> searchFunction) {
3670 +        if (searchFunction == null) throw new NullPointerException();
3671 +        return new SearchKeysTask<K,V,U>
3672 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3673 +             searchFunction, new AtomicReference<U>()).invoke();
3674 +    }
3675 +
3676 +    /**
3677 +     * Returns the result of accumulating all keys using the given
3678 +     * reducer to combine values, or null if none.
3679 +     *
3680 +     * @param parallelismThreshold the (estimated) number of elements
3681 +     * needed for this operation to be executed in parallel
3682 +     * @param reducer a commutative associative combining function
3683 +     * @return the result of accumulating all keys using the given
3684 +     * reducer to combine values, or null if none
3685 +     * @since 1.8
3686 +     */
3687 +    public K reduceKeys(long parallelismThreshold,
3688 +                        BiFun<? super K, ? super K, ? extends K> reducer) {
3689 +        if (reducer == null) throw new NullPointerException();
3690 +        return new ReduceKeysTask<K,V>
3691 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3692 +             null, reducer).invoke();
3693 +    }
3694 +
3695 +    /**
3696 +     * Returns the result of accumulating the given transformation
3697 +     * of all keys using the given reducer to combine values, or
3698 +     * null if none.
3699 +     *
3700 +     * @param parallelismThreshold the (estimated) number of elements
3701 +     * needed for this operation to be executed in parallel
3702 +     * @param transformer a function returning the transformation
3703 +     * for an element, or null if there is no transformation (in
3704 +     * which case it is not combined)
3705 +     * @param reducer a commutative associative combining function
3706 +     * @return the result of accumulating the given transformation
3707 +     * of all keys
3708 +     * @since 1.8
3709 +     */
3710 +    public <U> U reduceKeys(long parallelismThreshold,
3711 +                            Fun<? super K, ? extends U> transformer,
3712 +         BiFun<? super U, ? super U, ? extends U> reducer) {
3713 +        if (transformer == null || reducer == null)
3714 +            throw new NullPointerException();
3715 +        return new MapReduceKeysTask<K,V,U>
3716 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3717 +             null, transformer, reducer).invoke();
3718 +    }
3719 +
3720 +    /**
3721 +     * Returns the result of accumulating the given transformation
3722 +     * of all keys using the given reducer to combine values, and
3723 +     * the given basis as an identity value.
3724 +     *
3725 +     * @param parallelismThreshold the (estimated) number of elements
3726 +     * needed for this operation to be executed in parallel
3727 +     * @param transformer a function returning the transformation
3728 +     * for an element
3729 +     * @param basis the identity (initial default value) for the reduction
3730 +     * @param reducer a commutative associative combining function
3731 +     * @return the result of accumulating the given transformation
3732 +     * of all keys
3733 +     * @since 1.8
3734 +     */
3735 +    public double reduceKeysToDouble(long parallelismThreshold,
3736 +                                     ObjectToDouble<? super K> transformer,
3737 +                                     double basis,
3738 +                                     DoubleByDoubleToDouble reducer) {
3739 +        if (transformer == null || reducer == null)
3740 +            throw new NullPointerException();
3741 +        return new MapReduceKeysToDoubleTask<K,V>
3742 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3743 +             null, transformer, basis, reducer).invoke();
3744 +    }
3745 +
3746 +    /**
3747 +     * Returns the result of accumulating the given transformation
3748 +     * of all keys using the given reducer to combine values, and
3749 +     * the given basis as an identity value.
3750 +     *
3751 +     * @param parallelismThreshold the (estimated) number of elements
3752 +     * needed for this operation to be executed in parallel
3753 +     * @param transformer a function returning the transformation
3754 +     * for an element
3755 +     * @param basis the identity (initial default value) for the reduction
3756 +     * @param reducer a commutative associative combining function
3757 +     * @return the result of accumulating the given transformation
3758 +     * of all keys
3759 +     * @since 1.8
3760 +     */
3761 +    public long reduceKeysToLong(long parallelismThreshold,
3762 +                                 ObjectToLong<? super K> transformer,
3763 +                                 long basis,
3764 +                                 LongByLongToLong reducer) {
3765 +        if (transformer == null || reducer == null)
3766 +            throw new NullPointerException();
3767 +        return new MapReduceKeysToLongTask<K,V>
3768 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3769 +             null, transformer, basis, reducer).invoke();
3770 +    }
3771 +
3772 +    /**
3773 +     * Returns the result of accumulating the given transformation
3774 +     * of all keys using the given reducer to combine values, and
3775 +     * the given basis as an identity value.
3776 +     *
3777 +     * @param parallelismThreshold the (estimated) number of elements
3778 +     * needed for this operation to be executed in parallel
3779 +     * @param transformer a function returning the transformation
3780 +     * for an element
3781 +     * @param basis the identity (initial default value) for the reduction
3782 +     * @param reducer a commutative associative combining function
3783 +     * @return the result of accumulating the given transformation
3784 +     * of all keys
3785 +     * @since 1.8
3786 +     */
3787 +    public int reduceKeysToInt(long parallelismThreshold,
3788 +                               ObjectToInt<? super K> transformer,
3789 +                               int basis,
3790 +                               IntByIntToInt reducer) {
3791 +        if (transformer == null || reducer == null)
3792 +            throw new NullPointerException();
3793 +        return new MapReduceKeysToIntTask<K,V>
3794 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3795 +             null, transformer, basis, reducer).invoke();
3796 +    }
3797 +
3798 +    /**
3799 +     * Performs the given action for each value.
3800 +     *
3801 +     * @param parallelismThreshold the (estimated) number of elements
3802 +     * needed for this operation to be executed in parallel
3803 +     * @param action the action
3804 +     * @since 1.8
3805 +     */
3806 +    public void forEachValue(long parallelismThreshold,
3807 +                             Action<? super V> action) {
3808 +        if (action == null)
3809 +            throw new NullPointerException();
3810 +        new ForEachValueTask<K,V>
3811 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3812 +             action).invoke();
3813 +    }
3814 +
3815 +    /**
3816 +     * Performs the given action for each non-null transformation
3817 +     * of each value.
3818 +     *
3819 +     * @param parallelismThreshold the (estimated) number of elements
3820 +     * needed for this operation to be executed in parallel
3821 +     * @param transformer a function returning the transformation
3822 +     * for an element, or null if there is no transformation (in
3823 +     * which case the action is not applied)
3824 +     * @param action the action
3825 +     * @since 1.8
3826 +     */
3827 +    public <U> void forEachValue(long parallelismThreshold,
3828 +                                 Fun<? super V, ? extends U> transformer,
3829 +                                 Action<? super U> action) {
3830 +        if (transformer == null || action == null)
3831 +            throw new NullPointerException();
3832 +        new ForEachTransformedValueTask<K,V,U>
3833 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3834 +             transformer, action).invoke();
3835 +    }
3836 +
3837 +    /**
3838 +     * Returns a non-null result from applying the given search
3839 +     * function on each value, or null if none.  Upon success,
3840 +     * further element processing is suppressed and the results of
3841 +     * any other parallel invocations of the search function are
3842 +     * ignored.
3843 +     *
3844 +     * @param parallelismThreshold the (estimated) number of elements
3845 +     * needed for this operation to be executed in parallel
3846 +     * @param searchFunction a function returning a non-null
3847 +     * result on success, else null
3848 +     * @return a non-null result from applying the given search
3849 +     * function on each value, or null if none
3850 +     * @since 1.8
3851 +     */
3852 +    public <U> U searchValues(long parallelismThreshold,
3853 +                              Fun<? super V, ? extends U> searchFunction) {
3854 +        if (searchFunction == null) throw new NullPointerException();
3855 +        return new SearchValuesTask<K,V,U>
3856 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3857 +             searchFunction, new AtomicReference<U>()).invoke();
3858 +    }
3859 +
3860 +    /**
3861 +     * Returns the result of accumulating all values using the
3862 +     * given reducer to combine values, or null if none.
3863 +     *
3864 +     * @param parallelismThreshold the (estimated) number of elements
3865 +     * needed for this operation to be executed in parallel
3866 +     * @param reducer a commutative associative combining function
3867 +     * @return the result of accumulating all values
3868 +     * @since 1.8
3869 +     */
3870 +    public V reduceValues(long parallelismThreshold,
3871 +                          BiFun<? super V, ? super V, ? extends V> reducer) {
3872 +        if (reducer == null) throw new NullPointerException();
3873 +        return new ReduceValuesTask<K,V>
3874 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3875 +             null, reducer).invoke();
3876 +    }
3877 +
3878 +    /**
3879 +     * Returns the result of accumulating the given transformation
3880 +     * of all values using the given reducer to combine values, or
3881 +     * null if none.
3882 +     *
3883 +     * @param parallelismThreshold the (estimated) number of elements
3884 +     * needed for this operation to be executed in parallel
3885 +     * @param transformer a function returning the transformation
3886 +     * for an element, or null if there is no transformation (in
3887 +     * which case it is not combined)
3888 +     * @param reducer a commutative associative combining function
3889 +     * @return the result of accumulating the given transformation
3890 +     * of all values
3891 +     * @since 1.8
3892 +     */
3893 +    public <U> U reduceValues(long parallelismThreshold,
3894 +                              Fun<? super V, ? extends U> transformer,
3895 +                              BiFun<? super U, ? super U, ? extends U> reducer) {
3896 +        if (transformer == null || reducer == null)
3897 +            throw new NullPointerException();
3898 +        return new MapReduceValuesTask<K,V,U>
3899 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3900 +             null, transformer, reducer).invoke();
3901 +    }
3902 +
3903 +    /**
3904 +     * Returns the result of accumulating the given transformation
3905 +     * of all values using the given reducer to combine values,
3906 +     * and the given basis as an identity value.
3907 +     *
3908 +     * @param parallelismThreshold the (estimated) number of elements
3909 +     * needed for this operation to be executed in parallel
3910 +     * @param transformer a function returning the transformation
3911 +     * for an element
3912 +     * @param basis the identity (initial default value) for the reduction
3913 +     * @param reducer a commutative associative combining function
3914 +     * @return the result of accumulating the given transformation
3915 +     * of all values
3916 +     * @since 1.8
3917 +     */
3918 +    public double reduceValuesToDouble(long parallelismThreshold,
3919 +                                       ObjectToDouble<? super V> transformer,
3920 +                                       double basis,
3921 +                                       DoubleByDoubleToDouble reducer) {
3922 +        if (transformer == null || reducer == null)
3923 +            throw new NullPointerException();
3924 +        return new MapReduceValuesToDoubleTask<K,V>
3925 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3926 +             null, transformer, basis, reducer).invoke();
3927 +    }
3928 +
3929 +    /**
3930 +     * Returns the result of accumulating the given transformation
3931 +     * of all values using the given reducer to combine values,
3932 +     * and the given basis as an identity value.
3933 +     *
3934 +     * @param parallelismThreshold the (estimated) number of elements
3935 +     * needed for this operation to be executed in parallel
3936 +     * @param transformer a function returning the transformation
3937 +     * for an element
3938 +     * @param basis the identity (initial default value) for the reduction
3939 +     * @param reducer a commutative associative combining function
3940 +     * @return the result of accumulating the given transformation
3941 +     * of all values
3942 +     * @since 1.8
3943 +     */
3944 +    public long reduceValuesToLong(long parallelismThreshold,
3945 +                                   ObjectToLong<? super V> transformer,
3946 +                                   long basis,
3947 +                                   LongByLongToLong reducer) {
3948 +        if (transformer == null || reducer == null)
3949 +            throw new NullPointerException();
3950 +        return new MapReduceValuesToLongTask<K,V>
3951 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3952 +             null, transformer, basis, reducer).invoke();
3953 +    }
3954 +
3955 +    /**
3956 +     * Returns the result of accumulating the given transformation
3957 +     * of all values using the given reducer to combine values,
3958 +     * and the given basis as an identity value.
3959 +     *
3960 +     * @param parallelismThreshold the (estimated) number of elements
3961 +     * needed for this operation to be executed in parallel
3962 +     * @param transformer a function returning the transformation
3963 +     * for an element
3964 +     * @param basis the identity (initial default value) for the reduction
3965 +     * @param reducer a commutative associative combining function
3966 +     * @return the result of accumulating the given transformation
3967 +     * of all values
3968 +     * @since 1.8
3969 +     */
3970 +    public int reduceValuesToInt(long parallelismThreshold,
3971 +                                 ObjectToInt<? super V> transformer,
3972 +                                 int basis,
3973 +                                 IntByIntToInt reducer) {
3974 +        if (transformer == null || reducer == null)
3975 +            throw new NullPointerException();
3976 +        return new MapReduceValuesToIntTask<K,V>
3977 +            (null, batchFor(parallelismThreshold), 0, 0, table,
3978 +             null, transformer, basis, reducer).invoke();
3979 +    }
3980 +
3981 +    /**
3982 +     * Performs the given action for each entry.
3983 +     *
3984 +     * @param parallelismThreshold the (estimated) number of elements
3985 +     * needed for this operation to be executed in parallel
3986 +     * @param action the action
3987 +     * @since 1.8
3988 +     */
3989 +    public void forEachEntry(long parallelismThreshold,
3990 +                             Action<? super Map.Entry<K,V>> action) {
3991 +        if (action == null) throw new NullPointerException();
3992 +        new ForEachEntryTask<K,V>(null, batchFor(parallelismThreshold), 0, 0, table,
3993 +                                  action).invoke();
3994 +    }
3995 +
3996 +    /**
3997 +     * Performs the given action for each non-null transformation
3998 +     * of each entry.
3999 +     *
4000 +     * @param parallelismThreshold the (estimated) number of elements
4001 +     * needed for this operation to be executed in parallel
4002 +     * @param transformer a function returning the transformation
4003 +     * for an element, or null if there is no transformation (in
4004 +     * which case the action is not applied)
4005 +     * @param action the action
4006 +     * @since 1.8
4007 +     */
4008 +    public <U> void forEachEntry(long parallelismThreshold,
4009 +                                 Fun<Map.Entry<K,V>, ? extends U> transformer,
4010 +                                 Action<? super U> action) {
4011 +        if (transformer == null || action == null)
4012 +            throw new NullPointerException();
4013 +        new ForEachTransformedEntryTask<K,V,U>
4014 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4015 +             transformer, action).invoke();
4016 +    }
4017 +
4018 +    /**
4019 +     * Returns a non-null result from applying the given search
4020 +     * function on each entry, or null if none.  Upon success,
4021 +     * further element processing is suppressed and the results of
4022 +     * any other parallel invocations of the search function are
4023 +     * ignored.
4024 +     *
4025 +     * @param parallelismThreshold the (estimated) number of elements
4026 +     * needed for this operation to be executed in parallel
4027 +     * @param searchFunction a function returning a non-null
4028 +     * result on success, else null
4029 +     * @return a non-null result from applying the given search
4030 +     * function on each entry, or null if none
4031 +     * @since 1.8
4032 +     */
4033 +    public <U> U searchEntries(long parallelismThreshold,
4034 +                               Fun<Map.Entry<K,V>, ? extends U> searchFunction) {
4035 +        if (searchFunction == null) throw new NullPointerException();
4036 +        return new SearchEntriesTask<K,V,U>
4037 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4038 +             searchFunction, new AtomicReference<U>()).invoke();
4039 +    }
4040 +
4041 +    /**
4042 +     * Returns the result of accumulating all entries using the
4043 +     * given reducer to combine values, or null if none.
4044 +     *
4045 +     * @param parallelismThreshold the (estimated) number of elements
4046 +     * needed for this operation to be executed in parallel
4047 +     * @param reducer a commutative associative combining function
4048 +     * @return the result of accumulating all entries
4049 +     * @since 1.8
4050 +     */
4051 +    public Map.Entry<K,V> reduceEntries(long parallelismThreshold,
4052 +                                        BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4053 +        if (reducer == null) throw new NullPointerException();
4054 +        return new ReduceEntriesTask<K,V>
4055 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4056 +             null, reducer).invoke();
4057 +    }
4058 +
4059 +    /**
4060 +     * Returns the result of accumulating the given transformation
4061 +     * of all entries using the given reducer to combine values,
4062 +     * or null if none.
4063 +     *
4064 +     * @param parallelismThreshold the (estimated) number of elements
4065 +     * needed for this operation to be executed in parallel
4066 +     * @param transformer a function returning the transformation
4067 +     * for an element, or null if there is no transformation (in
4068 +     * which case it is not combined)
4069 +     * @param reducer a commutative associative combining function
4070 +     * @return the result of accumulating the given transformation
4071 +     * of all entries
4072 +     * @since 1.8
4073 +     */
4074 +    public <U> U reduceEntries(long parallelismThreshold,
4075 +                               Fun<Map.Entry<K,V>, ? extends U> transformer,
4076 +                               BiFun<? super U, ? super U, ? extends U> reducer) {
4077 +        if (transformer == null || reducer == null)
4078 +            throw new NullPointerException();
4079 +        return new MapReduceEntriesTask<K,V,U>
4080 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4081 +             null, transformer, reducer).invoke();
4082 +    }
4083 +
4084 +    /**
4085 +     * Returns the result of accumulating the given transformation
4086 +     * of all entries using the given reducer to combine values,
4087 +     * and the given basis as an identity value.
4088 +     *
4089 +     * @param parallelismThreshold the (estimated) number of elements
4090 +     * needed for this operation to be executed in parallel
4091 +     * @param transformer a function returning the transformation
4092 +     * for an element
4093 +     * @param basis the identity (initial default value) for the reduction
4094 +     * @param reducer a commutative associative combining function
4095 +     * @return the result of accumulating the given transformation
4096 +     * of all entries
4097 +     * @since 1.8
4098 +     */
4099 +    public double reduceEntriesToDouble(long parallelismThreshold,
4100 +                                        ObjectToDouble<Map.Entry<K,V>> transformer,
4101 +                                        double basis,
4102 +                                        DoubleByDoubleToDouble reducer) {
4103 +        if (transformer == null || reducer == null)
4104 +            throw new NullPointerException();
4105 +        return new MapReduceEntriesToDoubleTask<K,V>
4106 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4107 +             null, transformer, basis, reducer).invoke();
4108 +    }
4109 +
4110 +    /**
4111 +     * Returns the result of accumulating the given transformation
4112 +     * of all entries using the given reducer to combine values,
4113 +     * and the given basis as an identity value.
4114 +     *
4115 +     * @param parallelismThreshold the (estimated) number of elements
4116 +     * needed for this operation to be executed in parallel
4117 +     * @param transformer a function returning the transformation
4118 +     * for an element
4119 +     * @param basis the identity (initial default value) for the reduction
4120 +     * @param reducer a commutative associative combining function
4121 +     * @return the result of accumulating the given transformation
4122 +     * of all entries
4123 +     * @since 1.8
4124 +     */
4125 +    public long reduceEntriesToLong(long parallelismThreshold,
4126 +                                    ObjectToLong<Map.Entry<K,V>> transformer,
4127 +                                    long basis,
4128 +                                    LongByLongToLong reducer) {
4129 +        if (transformer == null || reducer == null)
4130 +            throw new NullPointerException();
4131 +        return new MapReduceEntriesToLongTask<K,V>
4132 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4133 +             null, transformer, basis, reducer).invoke();
4134 +    }
4135 +
4136 +    /**
4137 +     * Returns the result of accumulating the given transformation
4138 +     * of all entries using the given reducer to combine values,
4139 +     * and the given basis as an identity value.
4140 +     *
4141 +     * @param parallelismThreshold the (estimated) number of elements
4142 +     * needed for this operation to be executed in parallel
4143 +     * @param transformer a function returning the transformation
4144 +     * for an element
4145 +     * @param basis the identity (initial default value) for the reduction
4146 +     * @param reducer a commutative associative combining function
4147 +     * @return the result of accumulating the given transformation
4148 +     * of all entries
4149 +     * @since 1.8
4150 +     */
4151 +    public int reduceEntriesToInt(long parallelismThreshold,
4152 +                                  ObjectToInt<Map.Entry<K,V>> transformer,
4153 +                                  int basis,
4154 +                                  IntByIntToInt reducer) {
4155 +        if (transformer == null || reducer == null)
4156 +            throw new NullPointerException();
4157 +        return new MapReduceEntriesToIntTask<K,V>
4158 +            (null, batchFor(parallelismThreshold), 0, 0, table,
4159 +             null, transformer, basis, reducer).invoke();
4160 +    }
4161 +
4162 +
4163      /* ----------------Views -------------- */
4164  
4165      /**
4166       * Base class for views.
4167       */
4168 <    static abstract class MapView<K, V> {
4169 <        final ConcurrentHashMapV8<K, V> map;
4170 <        MapView(ConcurrentHashMapV8<K, V> map)  { this.map = map; }
4171 <        public final int size()                 { return map.size(); }
4172 <        public final boolean isEmpty()          { return map.isEmpty(); }
4173 <        public final void clear()               { map.clear(); }
4168 >    abstract static class CollectionView<K,V,E>
4169 >        implements Collection<E>, java.io.Serializable {
4170 >        private static final long serialVersionUID = 7249069246763182397L;
4171 >        final ConcurrentHashMapV8<K,V> map;
4172 >        CollectionView(ConcurrentHashMapV8<K,V> map)  { this.map = map; }
4173 >
4174 >        /**
4175 >         * Returns the map backing this view.
4176 >         *
4177 >         * @return the map backing this view
4178 >         */
4179 >        public ConcurrentHashMapV8<K,V> getMap() { return map; }
4180 >
4181 >        /**
4182 >         * Removes all of the elements from this view, by removing all
4183 >         * the mappings from the map backing this view.
4184 >         */
4185 >        public final void clear()      { map.clear(); }
4186 >        public final int size()        { return map.size(); }
4187 >        public final boolean isEmpty() { return map.isEmpty(); }
4188  
4189          // implementations below rely on concrete classes supplying these
4190 <        abstract public Iterator<?> iterator();
4191 <        abstract public boolean contains(Object o);
4192 <        abstract public boolean remove(Object o);
4190 >        // abstract methods
4191 >        /**
4192 >         * Returns a "weakly consistent" iterator that will never
4193 >         * throw {@link ConcurrentModificationException}, and
4194 >         * guarantees to traverse elements as they existed upon
4195 >         * construction of the iterator, and may (but is not
4196 >         * guaranteed to) reflect any modifications subsequent to
4197 >         * construction.
4198 >         */
4199 >        public abstract Iterator<E> iterator();
4200 >        public abstract boolean contains(Object o);
4201 >        public abstract boolean remove(Object o);
4202  
4203          private static final String oomeMsg = "Required array size too large";
4204  
4205          public final Object[] toArray() {
4206 <            long sz = map.longSize();
4207 <            if (sz > (long)(MAX_ARRAY_SIZE))
4206 >            long sz = map.mappingCount();
4207 >            if (sz > MAX_ARRAY_SIZE)
4208                  throw new OutOfMemoryError(oomeMsg);
4209              int n = (int)sz;
4210              Object[] r = new Object[n];
4211              int i = 0;
4212 <            Iterator<?> it = iterator();
2985 <            while (it.hasNext()) {
4212 >            for (E e : this) {
4213                  if (i == n) {
4214                      if (n >= MAX_ARRAY_SIZE)
4215                          throw new OutOfMemoryError(oomeMsg);
# Line 2992 | Line 4219 | public class ConcurrentHashMapV8<K, V>
4219                          n += (n >>> 1) + 1;
4220                      r = Arrays.copyOf(r, n);
4221                  }
4222 <                r[i++] = it.next();
4222 >                r[i++] = e;
4223              }
4224              return (i == n) ? r : Arrays.copyOf(r, i);
4225          }
4226  
4227          @SuppressWarnings("unchecked")
4228          public final <T> T[] toArray(T[] a) {
4229 <            long sz = map.longSize();
4230 <            if (sz > (long)(MAX_ARRAY_SIZE))
4229 >            long sz = map.mappingCount();
4230 >            if (sz > MAX_ARRAY_SIZE)
4231                  throw new OutOfMemoryError(oomeMsg);
4232              int m = (int)sz;
4233              T[] r = (a.length >= m) ? a :
# Line 3008 | Line 4235 | public class ConcurrentHashMapV8<K, V>
4235                  .newInstance(a.getClass().getComponentType(), m);
4236              int n = r.length;
4237              int i = 0;
4238 <            Iterator<?> it = iterator();
3012 <            while (it.hasNext()) {
4238 >            for (E e : this) {
4239                  if (i == n) {
4240                      if (n >= MAX_ARRAY_SIZE)
4241                          throw new OutOfMemoryError(oomeMsg);
# Line 3019 | Line 4245 | public class ConcurrentHashMapV8<K, V>
4245                          n += (n >>> 1) + 1;
4246                      r = Arrays.copyOf(r, n);
4247                  }
4248 <                r[i++] = (T)it.next();
4248 >                r[i++] = (T)e;
4249              }
4250              if (a == r && i < n) {
4251                  r[i] = null; // null-terminate
# Line 3028 | Line 4254 | public class ConcurrentHashMapV8<K, V>
4254              return (i == n) ? r : Arrays.copyOf(r, i);
4255          }
4256  
4257 <        public final int hashCode() {
4258 <            int h = 0;
4259 <            for (Iterator<?> it = iterator(); it.hasNext();)
4260 <                h += it.next().hashCode();
4261 <            return h;
4262 <        }
4263 <
4257 >        /**
4258 >         * Returns a string representation of this collection.
4259 >         * The string representation consists of the string representations
4260 >         * of the collection's elements in the order they are returned by
4261 >         * its iterator, enclosed in square brackets ({@code "[]"}).
4262 >         * Adjacent elements are separated by the characters {@code ", "}
4263 >         * (comma and space).  Elements are converted to strings as by
4264 >         * {@link String#valueOf(Object)}.
4265 >         *
4266 >         * @return a string representation of this collection
4267 >         */
4268          public final String toString() {
4269              StringBuilder sb = new StringBuilder();
4270              sb.append('[');
4271 <            Iterator<?> it = iterator();
4271 >            Iterator<E> it = iterator();
4272              if (it.hasNext()) {
4273                  for (;;) {
4274                      Object e = it.next();
# Line 3053 | Line 4283 | public class ConcurrentHashMapV8<K, V>
4283  
4284          public final boolean containsAll(Collection<?> c) {
4285              if (c != this) {
4286 <                for (Iterator<?> it = c.iterator(); it.hasNext();) {
3057 <                    Object e = it.next();
4286 >                for (Object e : c) {
4287                      if (e == null || !contains(e))
4288                          return false;
4289                  }
# Line 3064 | Line 4293 | public class ConcurrentHashMapV8<K, V>
4293  
4294          public final boolean removeAll(Collection<?> c) {
4295              boolean modified = false;
4296 <            for (Iterator<?> it = iterator(); it.hasNext();) {
4296 >            for (Iterator<E> it = iterator(); it.hasNext();) {
4297                  if (c.contains(it.next())) {
4298                      it.remove();
4299                      modified = true;
# Line 3075 | Line 4304 | public class ConcurrentHashMapV8<K, V>
4304  
4305          public final boolean retainAll(Collection<?> c) {
4306              boolean modified = false;
4307 <            for (Iterator<?> it = iterator(); it.hasNext();) {
4307 >            for (Iterator<E> it = iterator(); it.hasNext();) {
4308                  if (!c.contains(it.next())) {
4309                      it.remove();
4310                      modified = true;
# Line 3086 | Line 4315 | public class ConcurrentHashMapV8<K, V>
4315  
4316      }
4317  
4318 <    static final class KeySet<K,V> extends MapView<K,V> implements Set<K> {
4319 <        KeySet(ConcurrentHashMapV8<K, V> map)   { super(map); }
4320 <        public final boolean contains(Object o) { return map.containsKey(o); }
4321 <        public final boolean remove(Object o)   { return map.remove(o) != null; }
4322 <        public final Iterator<K> iterator() {
4323 <            return new KeyIterator<K,V>(map);
4318 >    /**
4319 >     * A view of a ConcurrentHashMapV8 as a {@link Set} of keys, in
4320 >     * which additions may optionally be enabled by mapping to a
4321 >     * common value.  This class cannot be directly instantiated.
4322 >     * See {@link #keySet() keySet()},
4323 >     * {@link #keySet(Object) keySet(V)},
4324 >     * {@link #newKeySet() newKeySet()},
4325 >     * {@link #newKeySet(int) newKeySet(int)}.
4326 >     *
4327 >     * @since 1.8
4328 >     */
4329 >    public static class KeySetView<K,V> extends CollectionView<K,V,K>
4330 >        implements Set<K>, java.io.Serializable {
4331 >        private static final long serialVersionUID = 7249069246763182397L;
4332 >        private final V value;
4333 >        KeySetView(ConcurrentHashMapV8<K,V> map, V value) {  // non-public
4334 >            super(map);
4335 >            this.value = value;
4336          }
4337 <        public final boolean add(K e) {
4338 <            throw new UnsupportedOperationException();
4337 >
4338 >        /**
4339 >         * Returns the default mapped value for additions,
4340 >         * or {@code null} if additions are not supported.
4341 >         *
4342 >         * @return the default mapped value for additions, or {@code null}
4343 >         * if not supported
4344 >         */
4345 >        public V getMappedValue() { return value; }
4346 >
4347 >        /**
4348 >         * {@inheritDoc}
4349 >         * @throws NullPointerException if the specified key is null
4350 >         */
4351 >        public boolean contains(Object o) { return map.containsKey(o); }
4352 >
4353 >        /**
4354 >         * Removes the key from this map view, by removing the key (and its
4355 >         * corresponding value) from the backing map.  This method does
4356 >         * nothing if the key is not in the map.
4357 >         *
4358 >         * @param  o the key to be removed from the backing map
4359 >         * @return {@code true} if the backing map contained the specified key
4360 >         * @throws NullPointerException if the specified key is null
4361 >         */
4362 >        public boolean remove(Object o) { return map.remove(o) != null; }
4363 >
4364 >        /**
4365 >         * @return an iterator over the keys of the backing map
4366 >         */
4367 >        public Iterator<K> iterator() {
4368 >            Node<K,V>[] t;
4369 >            ConcurrentHashMapV8<K,V> m = map;
4370 >            int f = (t = m.table) == null ? 0 : t.length;
4371 >            return new KeyIterator<K,V>(t, f, 0, f, m);
4372          }
4373 <        public final boolean addAll(Collection<? extends K> c) {
4374 <            throw new UnsupportedOperationException();
4373 >
4374 >        /**
4375 >         * Adds the specified key to this set view by mapping the key to
4376 >         * the default mapped value in the backing map, if defined.
4377 >         *
4378 >         * @param e key to be added
4379 >         * @return {@code true} if this set changed as a result of the call
4380 >         * @throws NullPointerException if the specified key is null
4381 >         * @throws UnsupportedOperationException if no default mapped value
4382 >         * for additions was provided
4383 >         */
4384 >        public boolean add(K e) {
4385 >            V v;
4386 >            if ((v = value) == null)
4387 >                throw new UnsupportedOperationException();
4388 >            return map.putVal(e, v, true) == null;
4389 >        }
4390 >
4391 >        /**
4392 >         * Adds all of the elements in the specified collection to this set,
4393 >         * as if by calling {@link #add} on each one.
4394 >         *
4395 >         * @param c the elements to be inserted into this set
4396 >         * @return {@code true} if this set changed as a result of the call
4397 >         * @throws NullPointerException if the collection or any of its
4398 >         * elements are {@code null}
4399 >         * @throws UnsupportedOperationException if no default mapped value
4400 >         * for additions was provided
4401 >         */
4402 >        public boolean addAll(Collection<? extends K> c) {
4403 >            boolean added = false;
4404 >            V v;
4405 >            if ((v = value) == null)
4406 >                throw new UnsupportedOperationException();
4407 >            for (K e : c) {
4408 >                if (map.putVal(e, v, true) == null)
4409 >                    added = true;
4410 >            }
4411 >            return added;
4412          }
4413 +
4414 +        public int hashCode() {
4415 +            int h = 0;
4416 +            for (K e : this)
4417 +                h += e.hashCode();
4418 +            return h;
4419 +        }
4420 +
4421          public boolean equals(Object o) {
4422              Set<?> c;
4423              return ((o instanceof Set) &&
4424                      ((c = (Set<?>)o) == this ||
4425                       (containsAll(c) && c.containsAll(this))));
4426          }
4427 +
4428 +        public ConcurrentHashMapSpliterator<K> spliterator() {
4429 +            Node<K,V>[] t;
4430 +            ConcurrentHashMapV8<K,V> m = map;
4431 +            long n = m.sumCount();
4432 +            int f = (t = m.table) == null ? 0 : t.length;
4433 +            return new KeySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4434 +        }
4435 +
4436 +        public void forEach(Action<? super K> action) {
4437 +            if (action == null) throw new NullPointerException();
4438 +            Node<K,V>[] t;
4439 +            if ((t = map.table) != null) {
4440 +                Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4441 +                for (Node<K,V> p; (p = it.advance()) != null; )
4442 +                    action.apply(p.key);
4443 +            }
4444 +        }
4445      }
4446  
4447 <    static final class Values<K,V> extends MapView<K,V>
4448 <        implements Collection<V> {
4449 <        Values(ConcurrentHashMapV8<K, V> map)   { super(map); }
4450 <        public final boolean contains(Object o) { return map.containsValue(o); }
4447 >    /**
4448 >     * A view of a ConcurrentHashMapV8 as a {@link Collection} of
4449 >     * values, in which additions are disabled. This class cannot be
4450 >     * directly instantiated. See {@link #values()}.
4451 >     */
4452 >    static final class ValuesView<K,V> extends CollectionView<K,V,V>
4453 >        implements Collection<V>, java.io.Serializable {
4454 >        private static final long serialVersionUID = 2249069246763182397L;
4455 >        ValuesView(ConcurrentHashMapV8<K,V> map) { super(map); }
4456 >        public final boolean contains(Object o) {
4457 >            return map.containsValue(o);
4458 >        }
4459 >
4460          public final boolean remove(Object o) {
4461              if (o != null) {
4462 <                Iterator<V> it = new ValueIterator<K,V>(map);
3117 <                while (it.hasNext()) {
4462 >                for (Iterator<V> it = iterator(); it.hasNext();) {
4463                      if (o.equals(it.next())) {
4464                          it.remove();
4465                          return true;
# Line 3123 | Line 4468 | public class ConcurrentHashMapV8<K, V>
4468              }
4469              return false;
4470          }
4471 +
4472          public final Iterator<V> iterator() {
4473 <            return new ValueIterator<K,V>(map);
4473 >            ConcurrentHashMapV8<K,V> m = map;
4474 >            Node<K,V>[] t;
4475 >            int f = (t = m.table) == null ? 0 : t.length;
4476 >            return new ValueIterator<K,V>(t, f, 0, f, m);
4477          }
4478 +
4479          public final boolean add(V e) {
4480              throw new UnsupportedOperationException();
4481          }
4482          public final boolean addAll(Collection<? extends V> c) {
4483              throw new UnsupportedOperationException();
4484          }
4485 +
4486 +        public ConcurrentHashMapSpliterator<V> spliterator() {
4487 +            Node<K,V>[] t;
4488 +            ConcurrentHashMapV8<K,V> m = map;
4489 +            long n = m.sumCount();
4490 +            int f = (t = m.table) == null ? 0 : t.length;
4491 +            return new ValueSpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4492 +        }
4493 +
4494 +        public void forEach(Action<? super V> action) {
4495 +            if (action == null) throw new NullPointerException();
4496 +            Node<K,V>[] t;
4497 +            if ((t = map.table) != null) {
4498 +                Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4499 +                for (Node<K,V> p; (p = it.advance()) != null; )
4500 +                    action.apply(p.val);
4501 +            }
4502 +        }
4503      }
4504  
4505 <    static final class EntrySet<K,V> extends MapView<K,V>
4506 <        implements Set<Map.Entry<K,V>> {
4507 <        EntrySet(ConcurrentHashMapV8<K, V> map) { super(map); }
4508 <        public final boolean contains(Object o) {
4505 >    /**
4506 >     * A view of a ConcurrentHashMapV8 as a {@link Set} of (key, value)
4507 >     * entries.  This class cannot be directly instantiated. See
4508 >     * {@link #entrySet()}.
4509 >     */
4510 >    static final class EntrySetView<K,V> extends CollectionView<K,V,Map.Entry<K,V>>
4511 >        implements Set<Map.Entry<K,V>>, java.io.Serializable {
4512 >        private static final long serialVersionUID = 2249069246763182397L;
4513 >        EntrySetView(ConcurrentHashMapV8<K,V> map) { super(map); }
4514 >
4515 >        public boolean contains(Object o) {
4516              Object k, v, r; Map.Entry<?,?> e;
4517              return ((o instanceof Map.Entry) &&
4518                      (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
# Line 3145 | Line 4520 | public class ConcurrentHashMapV8<K, V>
4520                      (v = e.getValue()) != null &&
4521                      (v == r || v.equals(r)));
4522          }
4523 <        public final boolean remove(Object o) {
4523 >
4524 >        public boolean remove(Object o) {
4525              Object k, v; Map.Entry<?,?> e;
4526              return ((o instanceof Map.Entry) &&
4527                      (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4528                      (v = e.getValue()) != null &&
4529                      map.remove(k, v));
4530          }
4531 <        public final Iterator<Map.Entry<K,V>> iterator() {
4532 <            return new EntryIterator<K,V>(map);
4531 >
4532 >        /**
4533 >         * @return an iterator over the entries of the backing map
4534 >         */
4535 >        public Iterator<Map.Entry<K,V>> iterator() {
4536 >            ConcurrentHashMapV8<K,V> m = map;
4537 >            Node<K,V>[] t;
4538 >            int f = (t = m.table) == null ? 0 : t.length;
4539 >            return new EntryIterator<K,V>(t, f, 0, f, m);
4540          }
4541 <        public final boolean add(Entry<K,V> e) {
4542 <            throw new UnsupportedOperationException();
4541 >
4542 >        public boolean add(Entry<K,V> e) {
4543 >            return map.putVal(e.getKey(), e.getValue(), false) == null;
4544          }
4545 <        public final boolean addAll(Collection<? extends Entry<K,V>> c) {
4546 <            throw new UnsupportedOperationException();
4545 >
4546 >        public boolean addAll(Collection<? extends Entry<K,V>> c) {
4547 >            boolean added = false;
4548 >            for (Entry<K,V> e : c) {
4549 >                if (add(e))
4550 >                    added = true;
4551 >            }
4552 >            return added;
4553          }
4554 <        public boolean equals(Object o) {
4554 >
4555 >        public final int hashCode() {
4556 >            int h = 0;
4557 >            Node<K,V>[] t;
4558 >            if ((t = map.table) != null) {
4559 >                Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4560 >                for (Node<K,V> p; (p = it.advance()) != null; ) {
4561 >                    h += p.hashCode();
4562 >                }
4563 >            }
4564 >            return h;
4565 >        }
4566 >
4567 >        public final boolean equals(Object o) {
4568              Set<?> c;
4569              return ((o instanceof Set) &&
4570                      ((c = (Set<?>)o) == this ||
4571                       (containsAll(c) && c.containsAll(this))));
4572          }
4573 +
4574 +        public ConcurrentHashMapSpliterator<Map.Entry<K,V>> spliterator() {
4575 +            Node<K,V>[] t;
4576 +            ConcurrentHashMapV8<K,V> m = map;
4577 +            long n = m.sumCount();
4578 +            int f = (t = m.table) == null ? 0 : t.length;
4579 +            return new EntrySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n, m);
4580 +        }
4581 +
4582 +        public void forEach(Action<? super Map.Entry<K,V>> action) {
4583 +            if (action == null) throw new NullPointerException();
4584 +            Node<K,V>[] t;
4585 +            if ((t = map.table) != null) {
4586 +                Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4587 +                for (Node<K,V> p; (p = it.advance()) != null; )
4588 +                    action.apply(new MapEntry<K,V>(p.key, p.val, map));
4589 +            }
4590 +        }
4591 +
4592      }
4593  
4594 <    /* ---------------- Serialization Support -------------- */
4594 >    // -------------------------------------------------------
4595  
4596      /**
4597 <     * Stripped-down version of helper class used in previous version,
4598 <     * declared for the sake of serialization compatibility
4597 >     * Base class for bulk tasks. Repeats some fields and code from
4598 >     * class Traverser, because we need to subclass CountedCompleter.
4599       */
4600 <    static class Segment<K,V> implements Serializable {
4601 <        private static final long serialVersionUID = 2249069246763182397L;
4602 <        final float loadFactor;
4603 <        Segment(float lf) { this.loadFactor = lf; }
4600 >    abstract static class BulkTask<K,V,R> extends CountedCompleter<R> {
4601 >        Node<K,V>[] tab;        // same as Traverser
4602 >        Node<K,V> next;
4603 >        int index;
4604 >        int baseIndex;
4605 >        int baseLimit;
4606 >        final int baseSize;
4607 >        int batch;              // split control
4608 >
4609 >        BulkTask(BulkTask<K,V,?> par, int b, int i, int f, Node<K,V>[] t) {
4610 >            super(par);
4611 >            this.batch = b;
4612 >            this.index = this.baseIndex = i;
4613 >            if ((this.tab = t) == null)
4614 >                this.baseSize = this.baseLimit = 0;
4615 >            else if (par == null)
4616 >                this.baseSize = this.baseLimit = t.length;
4617 >            else {
4618 >                this.baseLimit = f;
4619 >                this.baseSize = par.baseSize;
4620 >            }
4621 >        }
4622 >
4623 >        /**
4624 >         * Same as Traverser version
4625 >         */
4626 >        final Node<K,V> advance() {
4627 >            Node<K,V> e;
4628 >            if ((e = next) != null)
4629 >                e = e.next;
4630 >            for (;;) {
4631 >                Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
4632 >                if (e != null)
4633 >                    return next = e;
4634 >                if (baseIndex >= baseLimit || (t = tab) == null ||
4635 >                    (n = t.length) <= (i = index) || i < 0)
4636 >                    return next = null;
4637 >                if ((e = tabAt(t, index)) != null && e.hash < 0) {
4638 >                    if (e instanceof ForwardingNode) {
4639 >                        tab = ((ForwardingNode<K,V>)e).nextTable;
4640 >                        e = null;
4641 >                        continue;
4642 >                    }
4643 >                    else if (e instanceof TreeBin)
4644 >                        e = ((TreeBin<K,V>)e).first;
4645 >                    else
4646 >                        e = null;
4647 >                }
4648 >                if ((index += baseSize) >= n)
4649 >                    index = ++baseIndex;    // visit upper slots if present
4650 >            }
4651 >        }
4652      }
4653  
4654 <    /**
4655 <     * Saves the state of the {@code ConcurrentHashMapV8} instance to a
4656 <     * stream (i.e., serializes it).
4657 <     * @param s the stream
4658 <     * @serialData
4659 <     * the key (Object) and value (Object)
4660 <     * for each key-value mapping, followed by a null pair.
4661 <     * The key-value mappings are emitted in no particular order.
4662 <     */
4663 <    @SuppressWarnings("unchecked")
4664 <    private void writeObject(java.io.ObjectOutputStream s)
4665 <            throws java.io.IOException {
4666 <        if (segments == null) { // for serialization compatibility
4667 <            segments = (Segment<K,V>[])
4668 <                new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
4669 <            for (int i = 0; i < segments.length; ++i)
4670 <                segments[i] = new Segment<K,V>(LOAD_FACTOR);
4671 <        }
4672 <        s.defaultWriteObject();
4673 <        InternalIterator<K,V> it = new InternalIterator<K,V>(this);
4674 <        Object v;
4675 <        while ((v = it.advance()) != null) {
4676 <            s.writeObject(it.nextKey);
4677 <            s.writeObject(v);
4654 >    /*
4655 >     * Task classes. Coded in a regular but ugly format/style to
4656 >     * simplify checks that each variant differs in the right way from
4657 >     * others. The null screenings exist because compilers cannot tell
4658 >     * that we've already null-checked task arguments, so we force
4659 >     * simplest hoisted bypass to help avoid convoluted traps.
4660 >     */
4661 >    @SuppressWarnings("serial")
4662 >    static final class ForEachKeyTask<K,V>
4663 >        extends BulkTask<K,V,Void> {
4664 >        final Action<? super K> action;
4665 >        ForEachKeyTask
4666 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4667 >             Action<? super K> action) {
4668 >            super(p, b, i, f, t);
4669 >            this.action = action;
4670 >        }
4671 >        public final void compute() {
4672 >            final Action<? super K> action;
4673 >            if ((action = this.action) != null) {
4674 >                for (int i = baseIndex, f, h; batch > 0 &&
4675 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4676 >                    addToPendingCount(1);
4677 >                    new ForEachKeyTask<K,V>
4678 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4679 >                         action).fork();
4680 >                }
4681 >                for (Node<K,V> p; (p = advance()) != null;)
4682 >                    action.apply(p.key);
4683 >                propagateCompletion();
4684 >            }
4685 >        }
4686 >    }
4687 >
4688 >    @SuppressWarnings("serial")
4689 >    static final class ForEachValueTask<K,V>
4690 >        extends BulkTask<K,V,Void> {
4691 >        final Action<? super V> action;
4692 >        ForEachValueTask
4693 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4694 >             Action<? super V> action) {
4695 >            super(p, b, i, f, t);
4696 >            this.action = action;
4697 >        }
4698 >        public final void compute() {
4699 >            final Action<? super V> action;
4700 >            if ((action = this.action) != null) {
4701 >                for (int i = baseIndex, f, h; batch > 0 &&
4702 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4703 >                    addToPendingCount(1);
4704 >                    new ForEachValueTask<K,V>
4705 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4706 >                         action).fork();
4707 >                }
4708 >                for (Node<K,V> p; (p = advance()) != null;)
4709 >                    action.apply(p.val);
4710 >                propagateCompletion();
4711 >            }
4712 >        }
4713 >    }
4714 >
4715 >    @SuppressWarnings("serial")
4716 >    static final class ForEachEntryTask<K,V>
4717 >        extends BulkTask<K,V,Void> {
4718 >        final Action<? super Entry<K,V>> action;
4719 >        ForEachEntryTask
4720 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4721 >             Action<? super Entry<K,V>> action) {
4722 >            super(p, b, i, f, t);
4723 >            this.action = action;
4724 >        }
4725 >        public final void compute() {
4726 >            final Action<? super Entry<K,V>> action;
4727 >            if ((action = this.action) != null) {
4728 >                for (int i = baseIndex, f, h; batch > 0 &&
4729 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4730 >                    addToPendingCount(1);
4731 >                    new ForEachEntryTask<K,V>
4732 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4733 >                         action).fork();
4734 >                }
4735 >                for (Node<K,V> p; (p = advance()) != null; )
4736 >                    action.apply(p);
4737 >                propagateCompletion();
4738 >            }
4739 >        }
4740 >    }
4741 >
4742 >    @SuppressWarnings("serial")
4743 >    static final class ForEachMappingTask<K,V>
4744 >        extends BulkTask<K,V,Void> {
4745 >        final BiAction<? super K, ? super V> action;
4746 >        ForEachMappingTask
4747 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4748 >             BiAction<? super K,? super V> action) {
4749 >            super(p, b, i, f, t);
4750 >            this.action = action;
4751 >        }
4752 >        public final void compute() {
4753 >            final BiAction<? super K, ? super V> action;
4754 >            if ((action = this.action) != null) {
4755 >                for (int i = baseIndex, f, h; batch > 0 &&
4756 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4757 >                    addToPendingCount(1);
4758 >                    new ForEachMappingTask<K,V>
4759 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4760 >                         action).fork();
4761 >                }
4762 >                for (Node<K,V> p; (p = advance()) != null; )
4763 >                    action.apply(p.key, p.val);
4764 >                propagateCompletion();
4765 >            }
4766 >        }
4767 >    }
4768 >
4769 >    @SuppressWarnings("serial")
4770 >    static final class ForEachTransformedKeyTask<K,V,U>
4771 >        extends BulkTask<K,V,Void> {
4772 >        final Fun<? super K, ? extends U> transformer;
4773 >        final Action<? super U> action;
4774 >        ForEachTransformedKeyTask
4775 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4776 >             Fun<? super K, ? extends U> transformer, Action<? super U> action) {
4777 >            super(p, b, i, f, t);
4778 >            this.transformer = transformer; this.action = action;
4779 >        }
4780 >        public final void compute() {
4781 >            final Fun<? super K, ? extends U> transformer;
4782 >            final Action<? super U> action;
4783 >            if ((transformer = this.transformer) != null &&
4784 >                (action = this.action) != null) {
4785 >                for (int i = baseIndex, f, h; batch > 0 &&
4786 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4787 >                    addToPendingCount(1);
4788 >                    new ForEachTransformedKeyTask<K,V,U>
4789 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4790 >                         transformer, action).fork();
4791 >                }
4792 >                for (Node<K,V> p; (p = advance()) != null; ) {
4793 >                    U u;
4794 >                    if ((u = transformer.apply(p.key)) != null)
4795 >                        action.apply(u);
4796 >                }
4797 >                propagateCompletion();
4798 >            }
4799 >        }
4800 >    }
4801 >
4802 >    @SuppressWarnings("serial")
4803 >    static final class ForEachTransformedValueTask<K,V,U>
4804 >        extends BulkTask<K,V,Void> {
4805 >        final Fun<? super V, ? extends U> transformer;
4806 >        final Action<? super U> action;
4807 >        ForEachTransformedValueTask
4808 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4809 >             Fun<? super V, ? extends U> transformer, Action<? super U> action) {
4810 >            super(p, b, i, f, t);
4811 >            this.transformer = transformer; this.action = action;
4812 >        }
4813 >        public final void compute() {
4814 >            final Fun<? super V, ? extends U> transformer;
4815 >            final Action<? super U> action;
4816 >            if ((transformer = this.transformer) != null &&
4817 >                (action = this.action) != null) {
4818 >                for (int i = baseIndex, f, h; batch > 0 &&
4819 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4820 >                    addToPendingCount(1);
4821 >                    new ForEachTransformedValueTask<K,V,U>
4822 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4823 >                         transformer, action).fork();
4824 >                }
4825 >                for (Node<K,V> p; (p = advance()) != null; ) {
4826 >                    U u;
4827 >                    if ((u = transformer.apply(p.val)) != null)
4828 >                        action.apply(u);
4829 >                }
4830 >                propagateCompletion();
4831 >            }
4832 >        }
4833 >    }
4834 >
4835 >    @SuppressWarnings("serial")
4836 >    static final class ForEachTransformedEntryTask<K,V,U>
4837 >        extends BulkTask<K,V,Void> {
4838 >        final Fun<Map.Entry<K,V>, ? extends U> transformer;
4839 >        final Action<? super U> action;
4840 >        ForEachTransformedEntryTask
4841 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4842 >             Fun<Map.Entry<K,V>, ? extends U> transformer, Action<? super U> action) {
4843 >            super(p, b, i, f, t);
4844 >            this.transformer = transformer; this.action = action;
4845 >        }
4846 >        public final void compute() {
4847 >            final Fun<Map.Entry<K,V>, ? extends U> transformer;
4848 >            final Action<? super U> action;
4849 >            if ((transformer = this.transformer) != null &&
4850 >                (action = this.action) != null) {
4851 >                for (int i = baseIndex, f, h; batch > 0 &&
4852 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4853 >                    addToPendingCount(1);
4854 >                    new ForEachTransformedEntryTask<K,V,U>
4855 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4856 >                         transformer, action).fork();
4857 >                }
4858 >                for (Node<K,V> p; (p = advance()) != null; ) {
4859 >                    U u;
4860 >                    if ((u = transformer.apply(p)) != null)
4861 >                        action.apply(u);
4862 >                }
4863 >                propagateCompletion();
4864 >            }
4865 >        }
4866 >    }
4867 >
4868 >    @SuppressWarnings("serial")
4869 >    static final class ForEachTransformedMappingTask<K,V,U>
4870 >        extends BulkTask<K,V,Void> {
4871 >        final BiFun<? super K, ? super V, ? extends U> transformer;
4872 >        final Action<? super U> action;
4873 >        ForEachTransformedMappingTask
4874 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4875 >             BiFun<? super K, ? super V, ? extends U> transformer,
4876 >             Action<? super U> action) {
4877 >            super(p, b, i, f, t);
4878 >            this.transformer = transformer; this.action = action;
4879 >        }
4880 >        public final void compute() {
4881 >            final BiFun<? super K, ? super V, ? extends U> transformer;
4882 >            final Action<? super U> action;
4883 >            if ((transformer = this.transformer) != null &&
4884 >                (action = this.action) != null) {
4885 >                for (int i = baseIndex, f, h; batch > 0 &&
4886 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4887 >                    addToPendingCount(1);
4888 >                    new ForEachTransformedMappingTask<K,V,U>
4889 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4890 >                         transformer, action).fork();
4891 >                }
4892 >                for (Node<K,V> p; (p = advance()) != null; ) {
4893 >                    U u;
4894 >                    if ((u = transformer.apply(p.key, p.val)) != null)
4895 >                        action.apply(u);
4896 >                }
4897 >                propagateCompletion();
4898 >            }
4899 >        }
4900 >    }
4901 >
4902 >    @SuppressWarnings("serial")
4903 >    static final class SearchKeysTask<K,V,U>
4904 >        extends BulkTask<K,V,U> {
4905 >        final Fun<? super K, ? extends U> searchFunction;
4906 >        final AtomicReference<U> result;
4907 >        SearchKeysTask
4908 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4909 >             Fun<? super K, ? extends U> searchFunction,
4910 >             AtomicReference<U> result) {
4911 >            super(p, b, i, f, t);
4912 >            this.searchFunction = searchFunction; this.result = result;
4913 >        }
4914 >        public final U getRawResult() { return result.get(); }
4915 >        public final void compute() {
4916 >            final Fun<? super K, ? extends U> searchFunction;
4917 >            final AtomicReference<U> result;
4918 >            if ((searchFunction = this.searchFunction) != null &&
4919 >                (result = this.result) != null) {
4920 >                for (int i = baseIndex, f, h; batch > 0 &&
4921 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4922 >                    if (result.get() != null)
4923 >                        return;
4924 >                    addToPendingCount(1);
4925 >                    new SearchKeysTask<K,V,U>
4926 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4927 >                         searchFunction, result).fork();
4928 >                }
4929 >                while (result.get() == null) {
4930 >                    U u;
4931 >                    Node<K,V> p;
4932 >                    if ((p = advance()) == null) {
4933 >                        propagateCompletion();
4934 >                        break;
4935 >                    }
4936 >                    if ((u = searchFunction.apply(p.key)) != null) {
4937 >                        if (result.compareAndSet(null, u))
4938 >                            quietlyCompleteRoot();
4939 >                        break;
4940 >                    }
4941 >                }
4942 >            }
4943          }
3209        s.writeObject(null);
3210        s.writeObject(null);
3211        segments = null; // throw away
4944      }
4945  
4946 <    /**
4947 <     * Reconstitutes the instance from a stream (that is, deserializes it).
4948 <     * @param s the stream
4949 <     */
4950 <    @SuppressWarnings("unchecked")
4951 <    private void readObject(java.io.ObjectInputStream s)
4952 <            throws java.io.IOException, ClassNotFoundException {
4953 <        s.defaultReadObject();
4954 <        this.segments = null; // unneeded
4955 <        // initialize transient final field
4956 <        UNSAFE.putObjectVolatile(this, counterOffset, new LongAdder());
4946 >    @SuppressWarnings("serial")
4947 >    static final class SearchValuesTask<K,V,U>
4948 >        extends BulkTask<K,V,U> {
4949 >        final Fun<? super V, ? extends U> searchFunction;
4950 >        final AtomicReference<U> result;
4951 >        SearchValuesTask
4952 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4953 >             Fun<? super V, ? extends U> searchFunction,
4954 >             AtomicReference<U> result) {
4955 >            super(p, b, i, f, t);
4956 >            this.searchFunction = searchFunction; this.result = result;
4957 >        }
4958 >        public final U getRawResult() { return result.get(); }
4959 >        public final void compute() {
4960 >            final Fun<? super V, ? extends U> searchFunction;
4961 >            final AtomicReference<U> result;
4962 >            if ((searchFunction = this.searchFunction) != null &&
4963 >                (result = this.result) != null) {
4964 >                for (int i = baseIndex, f, h; batch > 0 &&
4965 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
4966 >                    if (result.get() != null)
4967 >                        return;
4968 >                    addToPendingCount(1);
4969 >                    new SearchValuesTask<K,V,U>
4970 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
4971 >                         searchFunction, result).fork();
4972 >                }
4973 >                while (result.get() == null) {
4974 >                    U u;
4975 >                    Node<K,V> p;
4976 >                    if ((p = advance()) == null) {
4977 >                        propagateCompletion();
4978 >                        break;
4979 >                    }
4980 >                    if ((u = searchFunction.apply(p.val)) != null) {
4981 >                        if (result.compareAndSet(null, u))
4982 >                            quietlyCompleteRoot();
4983 >                        break;
4984 >                    }
4985 >                }
4986 >            }
4987 >        }
4988 >    }
4989  
4990 <        // Create all nodes, then place in table once size is known
4991 <        long size = 0L;
4992 <        Node p = null;
4993 <        for (;;) {
4994 <            K k = (K) s.readObject();
4995 <            V v = (V) s.readObject();
4996 <            if (k != null && v != null) {
4997 <                int h = spread(k.hashCode());
4998 <                p = new Node(h, k, v, p);
4999 <                ++size;
4990 >    @SuppressWarnings("serial")
4991 >    static final class SearchEntriesTask<K,V,U>
4992 >        extends BulkTask<K,V,U> {
4993 >        final Fun<Entry<K,V>, ? extends U> searchFunction;
4994 >        final AtomicReference<U> result;
4995 >        SearchEntriesTask
4996 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4997 >             Fun<Entry<K,V>, ? extends U> searchFunction,
4998 >             AtomicReference<U> result) {
4999 >            super(p, b, i, f, t);
5000 >            this.searchFunction = searchFunction; this.result = result;
5001 >        }
5002 >        public final U getRawResult() { return result.get(); }
5003 >        public final void compute() {
5004 >            final Fun<Entry<K,V>, ? extends U> searchFunction;
5005 >            final AtomicReference<U> result;
5006 >            if ((searchFunction = this.searchFunction) != null &&
5007 >                (result = this.result) != null) {
5008 >                for (int i = baseIndex, f, h; batch > 0 &&
5009 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5010 >                    if (result.get() != null)
5011 >                        return;
5012 >                    addToPendingCount(1);
5013 >                    new SearchEntriesTask<K,V,U>
5014 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
5015 >                         searchFunction, result).fork();
5016 >                }
5017 >                while (result.get() == null) {
5018 >                    U u;
5019 >                    Node<K,V> p;
5020 >                    if ((p = advance()) == null) {
5021 >                        propagateCompletion();
5022 >                        break;
5023 >                    }
5024 >                    if ((u = searchFunction.apply(p)) != null) {
5025 >                        if (result.compareAndSet(null, u))
5026 >                            quietlyCompleteRoot();
5027 >                        return;
5028 >                    }
5029 >                }
5030              }
3237            else
3238                break;
5031          }
5032 <        if (p != null) {
5033 <            boolean init = false;
5034 <            int n;
5035 <            if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
5036 <                n = MAXIMUM_CAPACITY;
5037 <            else {
5038 <                int sz = (int)size;
5039 <                n = tableSizeFor(sz + (sz >>> 1) + 1);
5032 >    }
5033 >
5034 >    @SuppressWarnings("serial")
5035 >    static final class SearchMappingsTask<K,V,U>
5036 >        extends BulkTask<K,V,U> {
5037 >        final BiFun<? super K, ? super V, ? extends U> searchFunction;
5038 >        final AtomicReference<U> result;
5039 >        SearchMappingsTask
5040 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5041 >             BiFun<? super K, ? super V, ? extends U> searchFunction,
5042 >             AtomicReference<U> result) {
5043 >            super(p, b, i, f, t);
5044 >            this.searchFunction = searchFunction; this.result = result;
5045 >        }
5046 >        public final U getRawResult() { return result.get(); }
5047 >        public final void compute() {
5048 >            final BiFun<? super K, ? super V, ? extends U> searchFunction;
5049 >            final AtomicReference<U> result;
5050 >            if ((searchFunction = this.searchFunction) != null &&
5051 >                (result = this.result) != null) {
5052 >                for (int i = baseIndex, f, h; batch > 0 &&
5053 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5054 >                    if (result.get() != null)
5055 >                        return;
5056 >                    addToPendingCount(1);
5057 >                    new SearchMappingsTask<K,V,U>
5058 >                        (this, batch >>>= 1, baseLimit = h, f, tab,
5059 >                         searchFunction, result).fork();
5060 >                }
5061 >                while (result.get() == null) {
5062 >                    U u;
5063 >                    Node<K,V> p;
5064 >                    if ((p = advance()) == null) {
5065 >                        propagateCompletion();
5066 >                        break;
5067 >                    }
5068 >                    if ((u = searchFunction.apply(p.key, p.val)) != null) {
5069 >                        if (result.compareAndSet(null, u))
5070 >                            quietlyCompleteRoot();
5071 >                        break;
5072 >                    }
5073 >                }
5074              }
5075 <            int sc = sizeCtl;
5076 <            boolean collide = false;
5077 <            if (n > sc &&
5078 <                UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
5079 <                try {
5080 <                    if (table == null) {
5081 <                        init = true;
5082 <                        Node[] tab = new Node[n];
5083 <                        int mask = n - 1;
5084 <                        while (p != null) {
5085 <                            int j = p.hash & mask;
5086 <                            Node next = p.next;
5087 <                            Node q = p.next = tabAt(tab, j);
5088 <                            setTabAt(tab, j, p);
5089 <                            if (!collide && q != null && q.hash == p.hash)
5090 <                                collide = true;
5091 <                            p = next;
5075 >        }
5076 >    }
5077 >
5078 >    @SuppressWarnings("serial")
5079 >    static final class ReduceKeysTask<K,V>
5080 >        extends BulkTask<K,V,K> {
5081 >        final BiFun<? super K, ? super K, ? extends K> reducer;
5082 >        K result;
5083 >        ReduceKeysTask<K,V> rights, nextRight;
5084 >        ReduceKeysTask
5085 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5086 >             ReduceKeysTask<K,V> nextRight,
5087 >             BiFun<? super K, ? super K, ? extends K> reducer) {
5088 >            super(p, b, i, f, t); this.nextRight = nextRight;
5089 >            this.reducer = reducer;
5090 >        }
5091 >        public final K getRawResult() { return result; }
5092 >        public final void compute() {
5093 >            final BiFun<? super K, ? super K, ? extends K> reducer;
5094 >            if ((reducer = this.reducer) != null) {
5095 >                for (int i = baseIndex, f, h; batch > 0 &&
5096 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5097 >                    addToPendingCount(1);
5098 >                    (rights = new ReduceKeysTask<K,V>
5099 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5100 >                      rights, reducer)).fork();
5101 >                }
5102 >                K r = null;
5103 >                for (Node<K,V> p; (p = advance()) != null; ) {
5104 >                    K u = p.key;
5105 >                    r = (r == null) ? u : u == null ? r : reducer.apply(r, u);
5106 >                }
5107 >                result = r;
5108 >                CountedCompleter<?> c;
5109 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5110 >                    @SuppressWarnings("unchecked") ReduceKeysTask<K,V>
5111 >                        t = (ReduceKeysTask<K,V>)c,
5112 >                        s = t.rights;
5113 >                    while (s != null) {
5114 >                        K tr, sr;
5115 >                        if ((sr = s.result) != null)
5116 >                            t.result = (((tr = t.result) == null) ? sr :
5117 >                                        reducer.apply(tr, sr));
5118 >                        s = t.rights = s.nextRight;
5119 >                    }
5120 >                }
5121 >            }
5122 >        }
5123 >    }
5124 >
5125 >    @SuppressWarnings("serial")
5126 >    static final class ReduceValuesTask<K,V>
5127 >        extends BulkTask<K,V,V> {
5128 >        final BiFun<? super V, ? super V, ? extends V> reducer;
5129 >        V result;
5130 >        ReduceValuesTask<K,V> rights, nextRight;
5131 >        ReduceValuesTask
5132 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5133 >             ReduceValuesTask<K,V> nextRight,
5134 >             BiFun<? super V, ? super V, ? extends V> reducer) {
5135 >            super(p, b, i, f, t); this.nextRight = nextRight;
5136 >            this.reducer = reducer;
5137 >        }
5138 >        public final V getRawResult() { return result; }
5139 >        public final void compute() {
5140 >            final BiFun<? super V, ? super V, ? extends V> reducer;
5141 >            if ((reducer = this.reducer) != null) {
5142 >                for (int i = baseIndex, f, h; batch > 0 &&
5143 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5144 >                    addToPendingCount(1);
5145 >                    (rights = new ReduceValuesTask<K,V>
5146 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5147 >                      rights, reducer)).fork();
5148 >                }
5149 >                V r = null;
5150 >                for (Node<K,V> p; (p = advance()) != null; ) {
5151 >                    V v = p.val;
5152 >                    r = (r == null) ? v : reducer.apply(r, v);
5153 >                }
5154 >                result = r;
5155 >                CountedCompleter<?> c;
5156 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5157 >                    @SuppressWarnings("unchecked") ReduceValuesTask<K,V>
5158 >                        t = (ReduceValuesTask<K,V>)c,
5159 >                        s = t.rights;
5160 >                    while (s != null) {
5161 >                        V tr, sr;
5162 >                        if ((sr = s.result) != null)
5163 >                            t.result = (((tr = t.result) == null) ? sr :
5164 >                                        reducer.apply(tr, sr));
5165 >                        s = t.rights = s.nextRight;
5166 >                    }
5167 >                }
5168 >            }
5169 >        }
5170 >    }
5171 >
5172 >    @SuppressWarnings("serial")
5173 >    static final class ReduceEntriesTask<K,V>
5174 >        extends BulkTask<K,V,Map.Entry<K,V>> {
5175 >        final BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5176 >        Map.Entry<K,V> result;
5177 >        ReduceEntriesTask<K,V> rights, nextRight;
5178 >        ReduceEntriesTask
5179 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5180 >             ReduceEntriesTask<K,V> nextRight,
5181 >             BiFun<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5182 >            super(p, b, i, f, t); this.nextRight = nextRight;
5183 >            this.reducer = reducer;
5184 >        }
5185 >        public final Map.Entry<K,V> getRawResult() { return result; }
5186 >        public final void compute() {
5187 >            final BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5188 >            if ((reducer = this.reducer) != null) {
5189 >                for (int i = baseIndex, f, h; batch > 0 &&
5190 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5191 >                    addToPendingCount(1);
5192 >                    (rights = new ReduceEntriesTask<K,V>
5193 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5194 >                      rights, reducer)).fork();
5195 >                }
5196 >                Map.Entry<K,V> r = null;
5197 >                for (Node<K,V> p; (p = advance()) != null; )
5198 >                    r = (r == null) ? p : reducer.apply(r, p);
5199 >                result = r;
5200 >                CountedCompleter<?> c;
5201 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5202 >                    @SuppressWarnings("unchecked") ReduceEntriesTask<K,V>
5203 >                        t = (ReduceEntriesTask<K,V>)c,
5204 >                        s = t.rights;
5205 >                    while (s != null) {
5206 >                        Map.Entry<K,V> tr, sr;
5207 >                        if ((sr = s.result) != null)
5208 >                            t.result = (((tr = t.result) == null) ? sr :
5209 >                                        reducer.apply(tr, sr));
5210 >                        s = t.rights = s.nextRight;
5211 >                    }
5212 >                }
5213 >            }
5214 >        }
5215 >    }
5216 >
5217 >    @SuppressWarnings("serial")
5218 >    static final class MapReduceKeysTask<K,V,U>
5219 >        extends BulkTask<K,V,U> {
5220 >        final Fun<? super K, ? extends U> transformer;
5221 >        final BiFun<? super U, ? super U, ? extends U> reducer;
5222 >        U result;
5223 >        MapReduceKeysTask<K,V,U> rights, nextRight;
5224 >        MapReduceKeysTask
5225 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5226 >             MapReduceKeysTask<K,V,U> nextRight,
5227 >             Fun<? super K, ? extends U> transformer,
5228 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5229 >            super(p, b, i, f, t); this.nextRight = nextRight;
5230 >            this.transformer = transformer;
5231 >            this.reducer = reducer;
5232 >        }
5233 >        public final U getRawResult() { return result; }
5234 >        public final void compute() {
5235 >            final Fun<? super K, ? extends U> transformer;
5236 >            final BiFun<? super U, ? super U, ? extends U> reducer;
5237 >            if ((transformer = this.transformer) != null &&
5238 >                (reducer = this.reducer) != null) {
5239 >                for (int i = baseIndex, f, h; batch > 0 &&
5240 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5241 >                    addToPendingCount(1);
5242 >                    (rights = new MapReduceKeysTask<K,V,U>
5243 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5244 >                      rights, transformer, reducer)).fork();
5245 >                }
5246 >                U r = null;
5247 >                for (Node<K,V> p; (p = advance()) != null; ) {
5248 >                    U u;
5249 >                    if ((u = transformer.apply(p.key)) != null)
5250 >                        r = (r == null) ? u : reducer.apply(r, u);
5251 >                }
5252 >                result = r;
5253 >                CountedCompleter<?> c;
5254 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5255 >                    @SuppressWarnings("unchecked") MapReduceKeysTask<K,V,U>
5256 >                        t = (MapReduceKeysTask<K,V,U>)c,
5257 >                        s = t.rights;
5258 >                    while (s != null) {
5259 >                        U tr, sr;
5260 >                        if ((sr = s.result) != null)
5261 >                            t.result = (((tr = t.result) == null) ? sr :
5262 >                                        reducer.apply(tr, sr));
5263 >                        s = t.rights = s.nextRight;
5264 >                    }
5265 >                }
5266 >            }
5267 >        }
5268 >    }
5269 >
5270 >    @SuppressWarnings("serial")
5271 >    static final class MapReduceValuesTask<K,V,U>
5272 >        extends BulkTask<K,V,U> {
5273 >        final Fun<? super V, ? extends U> transformer;
5274 >        final BiFun<? super U, ? super U, ? extends U> reducer;
5275 >        U result;
5276 >        MapReduceValuesTask<K,V,U> rights, nextRight;
5277 >        MapReduceValuesTask
5278 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5279 >             MapReduceValuesTask<K,V,U> nextRight,
5280 >             Fun<? super V, ? extends U> transformer,
5281 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5282 >            super(p, b, i, f, t); this.nextRight = nextRight;
5283 >            this.transformer = transformer;
5284 >            this.reducer = reducer;
5285 >        }
5286 >        public final U getRawResult() { return result; }
5287 >        public final void compute() {
5288 >            final Fun<? super V, ? extends U> transformer;
5289 >            final BiFun<? super U, ? super U, ? extends U> reducer;
5290 >            if ((transformer = this.transformer) != null &&
5291 >                (reducer = this.reducer) != null) {
5292 >                for (int i = baseIndex, f, h; batch > 0 &&
5293 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5294 >                    addToPendingCount(1);
5295 >                    (rights = new MapReduceValuesTask<K,V,U>
5296 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5297 >                      rights, transformer, reducer)).fork();
5298 >                }
5299 >                U r = null;
5300 >                for (Node<K,V> p; (p = advance()) != null; ) {
5301 >                    U u;
5302 >                    if ((u = transformer.apply(p.val)) != null)
5303 >                        r = (r == null) ? u : reducer.apply(r, u);
5304 >                }
5305 >                result = r;
5306 >                CountedCompleter<?> c;
5307 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5308 >                    @SuppressWarnings("unchecked") MapReduceValuesTask<K,V,U>
5309 >                        t = (MapReduceValuesTask<K,V,U>)c,
5310 >                        s = t.rights;
5311 >                    while (s != null) {
5312 >                        U tr, sr;
5313 >                        if ((sr = s.result) != null)
5314 >                            t.result = (((tr = t.result) == null) ? sr :
5315 >                                        reducer.apply(tr, sr));
5316 >                        s = t.rights = s.nextRight;
5317 >                    }
5318 >                }
5319 >            }
5320 >        }
5321 >    }
5322 >
5323 >    @SuppressWarnings("serial")
5324 >    static final class MapReduceEntriesTask<K,V,U>
5325 >        extends BulkTask<K,V,U> {
5326 >        final Fun<Map.Entry<K,V>, ? extends U> transformer;
5327 >        final BiFun<? super U, ? super U, ? extends U> reducer;
5328 >        U result;
5329 >        MapReduceEntriesTask<K,V,U> rights, nextRight;
5330 >        MapReduceEntriesTask
5331 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5332 >             MapReduceEntriesTask<K,V,U> nextRight,
5333 >             Fun<Map.Entry<K,V>, ? extends U> transformer,
5334 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5335 >            super(p, b, i, f, t); this.nextRight = nextRight;
5336 >            this.transformer = transformer;
5337 >            this.reducer = reducer;
5338 >        }
5339 >        public final U getRawResult() { return result; }
5340 >        public final void compute() {
5341 >            final Fun<Map.Entry<K,V>, ? extends U> transformer;
5342 >            final BiFun<? super U, ? super U, ? extends U> reducer;
5343 >            if ((transformer = this.transformer) != null &&
5344 >                (reducer = this.reducer) != null) {
5345 >                for (int i = baseIndex, f, h; batch > 0 &&
5346 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5347 >                    addToPendingCount(1);
5348 >                    (rights = new MapReduceEntriesTask<K,V,U>
5349 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5350 >                      rights, transformer, reducer)).fork();
5351 >                }
5352 >                U r = null;
5353 >                for (Node<K,V> p; (p = advance()) != null; ) {
5354 >                    U u;
5355 >                    if ((u = transformer.apply(p)) != null)
5356 >                        r = (r == null) ? u : reducer.apply(r, u);
5357 >                }
5358 >                result = r;
5359 >                CountedCompleter<?> c;
5360 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5361 >                    @SuppressWarnings("unchecked") MapReduceEntriesTask<K,V,U>
5362 >                        t = (MapReduceEntriesTask<K,V,U>)c,
5363 >                        s = t.rights;
5364 >                    while (s != null) {
5365 >                        U tr, sr;
5366 >                        if ((sr = s.result) != null)
5367 >                            t.result = (((tr = t.result) == null) ? sr :
5368 >                                        reducer.apply(tr, sr));
5369 >                        s = t.rights = s.nextRight;
5370 >                    }
5371 >                }
5372 >            }
5373 >        }
5374 >    }
5375 >
5376 >    @SuppressWarnings("serial")
5377 >    static final class MapReduceMappingsTask<K,V,U>
5378 >        extends BulkTask<K,V,U> {
5379 >        final BiFun<? super K, ? super V, ? extends U> transformer;
5380 >        final BiFun<? super U, ? super U, ? extends U> reducer;
5381 >        U result;
5382 >        MapReduceMappingsTask<K,V,U> rights, nextRight;
5383 >        MapReduceMappingsTask
5384 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5385 >             MapReduceMappingsTask<K,V,U> nextRight,
5386 >             BiFun<? super K, ? super V, ? extends U> transformer,
5387 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5388 >            super(p, b, i, f, t); this.nextRight = nextRight;
5389 >            this.transformer = transformer;
5390 >            this.reducer = reducer;
5391 >        }
5392 >        public final U getRawResult() { return result; }
5393 >        public final void compute() {
5394 >            final BiFun<? super K, ? super V, ? extends U> transformer;
5395 >            final BiFun<? super U, ? super U, ? extends U> reducer;
5396 >            if ((transformer = this.transformer) != null &&
5397 >                (reducer = this.reducer) != null) {
5398 >                for (int i = baseIndex, f, h; batch > 0 &&
5399 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5400 >                    addToPendingCount(1);
5401 >                    (rights = new MapReduceMappingsTask<K,V,U>
5402 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5403 >                      rights, transformer, reducer)).fork();
5404 >                }
5405 >                U r = null;
5406 >                for (Node<K,V> p; (p = advance()) != null; ) {
5407 >                    U u;
5408 >                    if ((u = transformer.apply(p.key, p.val)) != null)
5409 >                        r = (r == null) ? u : reducer.apply(r, u);
5410 >                }
5411 >                result = r;
5412 >                CountedCompleter<?> c;
5413 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5414 >                    @SuppressWarnings("unchecked") MapReduceMappingsTask<K,V,U>
5415 >                        t = (MapReduceMappingsTask<K,V,U>)c,
5416 >                        s = t.rights;
5417 >                    while (s != null) {
5418 >                        U tr, sr;
5419 >                        if ((sr = s.result) != null)
5420 >                            t.result = (((tr = t.result) == null) ? sr :
5421 >                                        reducer.apply(tr, sr));
5422 >                        s = t.rights = s.nextRight;
5423 >                    }
5424 >                }
5425 >            }
5426 >        }
5427 >    }
5428 >
5429 >    @SuppressWarnings("serial")
5430 >    static final class MapReduceKeysToDoubleTask<K,V>
5431 >        extends BulkTask<K,V,Double> {
5432 >        final ObjectToDouble<? super K> transformer;
5433 >        final DoubleByDoubleToDouble reducer;
5434 >        final double basis;
5435 >        double result;
5436 >        MapReduceKeysToDoubleTask<K,V> rights, nextRight;
5437 >        MapReduceKeysToDoubleTask
5438 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5439 >             MapReduceKeysToDoubleTask<K,V> nextRight,
5440 >             ObjectToDouble<? super K> transformer,
5441 >             double basis,
5442 >             DoubleByDoubleToDouble reducer) {
5443 >            super(p, b, i, f, t); this.nextRight = nextRight;
5444 >            this.transformer = transformer;
5445 >            this.basis = basis; this.reducer = reducer;
5446 >        }
5447 >        public final Double getRawResult() { return result; }
5448 >        public final void compute() {
5449 >            final ObjectToDouble<? super K> transformer;
5450 >            final DoubleByDoubleToDouble reducer;
5451 >            if ((transformer = this.transformer) != null &&
5452 >                (reducer = this.reducer) != null) {
5453 >                double r = this.basis;
5454 >                for (int i = baseIndex, f, h; batch > 0 &&
5455 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5456 >                    addToPendingCount(1);
5457 >                    (rights = new MapReduceKeysToDoubleTask<K,V>
5458 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5459 >                      rights, transformer, r, reducer)).fork();
5460 >                }
5461 >                for (Node<K,V> p; (p = advance()) != null; )
5462 >                    r = reducer.apply(r, transformer.apply(p.key));
5463 >                result = r;
5464 >                CountedCompleter<?> c;
5465 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5466 >                    @SuppressWarnings("unchecked") MapReduceKeysToDoubleTask<K,V>
5467 >                        t = (MapReduceKeysToDoubleTask<K,V>)c,
5468 >                        s = t.rights;
5469 >                    while (s != null) {
5470 >                        t.result = reducer.apply(t.result, s.result);
5471 >                        s = t.rights = s.nextRight;
5472 >                    }
5473 >                }
5474 >            }
5475 >        }
5476 >    }
5477 >
5478 >    @SuppressWarnings("serial")
5479 >    static final class MapReduceValuesToDoubleTask<K,V>
5480 >        extends BulkTask<K,V,Double> {
5481 >        final ObjectToDouble<? super V> transformer;
5482 >        final DoubleByDoubleToDouble reducer;
5483 >        final double basis;
5484 >        double result;
5485 >        MapReduceValuesToDoubleTask<K,V> rights, nextRight;
5486 >        MapReduceValuesToDoubleTask
5487 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5488 >             MapReduceValuesToDoubleTask<K,V> nextRight,
5489 >             ObjectToDouble<? super V> transformer,
5490 >             double basis,
5491 >             DoubleByDoubleToDouble reducer) {
5492 >            super(p, b, i, f, t); this.nextRight = nextRight;
5493 >            this.transformer = transformer;
5494 >            this.basis = basis; this.reducer = reducer;
5495 >        }
5496 >        public final Double getRawResult() { return result; }
5497 >        public final void compute() {
5498 >            final ObjectToDouble<? super V> transformer;
5499 >            final DoubleByDoubleToDouble reducer;
5500 >            if ((transformer = this.transformer) != null &&
5501 >                (reducer = this.reducer) != null) {
5502 >                double r = this.basis;
5503 >                for (int i = baseIndex, f, h; batch > 0 &&
5504 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5505 >                    addToPendingCount(1);
5506 >                    (rights = new MapReduceValuesToDoubleTask<K,V>
5507 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5508 >                      rights, transformer, r, reducer)).fork();
5509 >                }
5510 >                for (Node<K,V> p; (p = advance()) != null; )
5511 >                    r = reducer.apply(r, transformer.apply(p.val));
5512 >                result = r;
5513 >                CountedCompleter<?> c;
5514 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5515 >                    @SuppressWarnings("unchecked") MapReduceValuesToDoubleTask<K,V>
5516 >                        t = (MapReduceValuesToDoubleTask<K,V>)c,
5517 >                        s = t.rights;
5518 >                    while (s != null) {
5519 >                        t.result = reducer.apply(t.result, s.result);
5520 >                        s = t.rights = s.nextRight;
5521 >                    }
5522 >                }
5523 >            }
5524 >        }
5525 >    }
5526 >
5527 >    @SuppressWarnings("serial")
5528 >    static final class MapReduceEntriesToDoubleTask<K,V>
5529 >        extends BulkTask<K,V,Double> {
5530 >        final ObjectToDouble<Map.Entry<K,V>> transformer;
5531 >        final DoubleByDoubleToDouble reducer;
5532 >        final double basis;
5533 >        double result;
5534 >        MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
5535 >        MapReduceEntriesToDoubleTask
5536 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5537 >             MapReduceEntriesToDoubleTask<K,V> nextRight,
5538 >             ObjectToDouble<Map.Entry<K,V>> transformer,
5539 >             double basis,
5540 >             DoubleByDoubleToDouble reducer) {
5541 >            super(p, b, i, f, t); this.nextRight = nextRight;
5542 >            this.transformer = transformer;
5543 >            this.basis = basis; this.reducer = reducer;
5544 >        }
5545 >        public final Double getRawResult() { return result; }
5546 >        public final void compute() {
5547 >            final ObjectToDouble<Map.Entry<K,V>> transformer;
5548 >            final DoubleByDoubleToDouble reducer;
5549 >            if ((transformer = this.transformer) != null &&
5550 >                (reducer = this.reducer) != null) {
5551 >                double r = this.basis;
5552 >                for (int i = baseIndex, f, h; batch > 0 &&
5553 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5554 >                    addToPendingCount(1);
5555 >                    (rights = new MapReduceEntriesToDoubleTask<K,V>
5556 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5557 >                      rights, transformer, r, reducer)).fork();
5558 >                }
5559 >                for (Node<K,V> p; (p = advance()) != null; )
5560 >                    r = reducer.apply(r, transformer.apply(p));
5561 >                result = r;
5562 >                CountedCompleter<?> c;
5563 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5564 >                    @SuppressWarnings("unchecked") MapReduceEntriesToDoubleTask<K,V>
5565 >                        t = (MapReduceEntriesToDoubleTask<K,V>)c,
5566 >                        s = t.rights;
5567 >                    while (s != null) {
5568 >                        t.result = reducer.apply(t.result, s.result);
5569 >                        s = t.rights = s.nextRight;
5570 >                    }
5571 >                }
5572 >            }
5573 >        }
5574 >    }
5575 >
5576 >    @SuppressWarnings("serial")
5577 >    static final class MapReduceMappingsToDoubleTask<K,V>
5578 >        extends BulkTask<K,V,Double> {
5579 >        final ObjectByObjectToDouble<? super K, ? super V> transformer;
5580 >        final DoubleByDoubleToDouble reducer;
5581 >        final double basis;
5582 >        double result;
5583 >        MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
5584 >        MapReduceMappingsToDoubleTask
5585 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5586 >             MapReduceMappingsToDoubleTask<K,V> nextRight,
5587 >             ObjectByObjectToDouble<? super K, ? super V> transformer,
5588 >             double basis,
5589 >             DoubleByDoubleToDouble reducer) {
5590 >            super(p, b, i, f, t); this.nextRight = nextRight;
5591 >            this.transformer = transformer;
5592 >            this.basis = basis; this.reducer = reducer;
5593 >        }
5594 >        public final Double getRawResult() { return result; }
5595 >        public final void compute() {
5596 >            final ObjectByObjectToDouble<? super K, ? super V> transformer;
5597 >            final DoubleByDoubleToDouble reducer;
5598 >            if ((transformer = this.transformer) != null &&
5599 >                (reducer = this.reducer) != null) {
5600 >                double r = this.basis;
5601 >                for (int i = baseIndex, f, h; batch > 0 &&
5602 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5603 >                    addToPendingCount(1);
5604 >                    (rights = new MapReduceMappingsToDoubleTask<K,V>
5605 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5606 >                      rights, transformer, r, reducer)).fork();
5607 >                }
5608 >                for (Node<K,V> p; (p = advance()) != null; )
5609 >                    r = reducer.apply(r, transformer.apply(p.key, p.val));
5610 >                result = r;
5611 >                CountedCompleter<?> c;
5612 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5613 >                    @SuppressWarnings("unchecked") MapReduceMappingsToDoubleTask<K,V>
5614 >                        t = (MapReduceMappingsToDoubleTask<K,V>)c,
5615 >                        s = t.rights;
5616 >                    while (s != null) {
5617 >                        t.result = reducer.apply(t.result, s.result);
5618 >                        s = t.rights = s.nextRight;
5619 >                    }
5620 >                }
5621 >            }
5622 >        }
5623 >    }
5624 >
5625 >    @SuppressWarnings("serial")
5626 >    static final class MapReduceKeysToLongTask<K,V>
5627 >        extends BulkTask<K,V,Long> {
5628 >        final ObjectToLong<? super K> transformer;
5629 >        final LongByLongToLong reducer;
5630 >        final long basis;
5631 >        long result;
5632 >        MapReduceKeysToLongTask<K,V> rights, nextRight;
5633 >        MapReduceKeysToLongTask
5634 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5635 >             MapReduceKeysToLongTask<K,V> nextRight,
5636 >             ObjectToLong<? super K> transformer,
5637 >             long basis,
5638 >             LongByLongToLong reducer) {
5639 >            super(p, b, i, f, t); this.nextRight = nextRight;
5640 >            this.transformer = transformer;
5641 >            this.basis = basis; this.reducer = reducer;
5642 >        }
5643 >        public final Long getRawResult() { return result; }
5644 >        public final void compute() {
5645 >            final ObjectToLong<? super K> transformer;
5646 >            final LongByLongToLong reducer;
5647 >            if ((transformer = this.transformer) != null &&
5648 >                (reducer = this.reducer) != null) {
5649 >                long r = this.basis;
5650 >                for (int i = baseIndex, f, h; batch > 0 &&
5651 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5652 >                    addToPendingCount(1);
5653 >                    (rights = new MapReduceKeysToLongTask<K,V>
5654 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5655 >                      rights, transformer, r, reducer)).fork();
5656 >                }
5657 >                for (Node<K,V> p; (p = advance()) != null; )
5658 >                    r = reducer.apply(r, transformer.apply(p.key));
5659 >                result = r;
5660 >                CountedCompleter<?> c;
5661 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5662 >                    @SuppressWarnings("unchecked") MapReduceKeysToLongTask<K,V>
5663 >                        t = (MapReduceKeysToLongTask<K,V>)c,
5664 >                        s = t.rights;
5665 >                    while (s != null) {
5666 >                        t.result = reducer.apply(t.result, s.result);
5667 >                        s = t.rights = s.nextRight;
5668 >                    }
5669 >                }
5670 >            }
5671 >        }
5672 >    }
5673 >
5674 >    @SuppressWarnings("serial")
5675 >    static final class MapReduceValuesToLongTask<K,V>
5676 >        extends BulkTask<K,V,Long> {
5677 >        final ObjectToLong<? super V> transformer;
5678 >        final LongByLongToLong reducer;
5679 >        final long basis;
5680 >        long result;
5681 >        MapReduceValuesToLongTask<K,V> rights, nextRight;
5682 >        MapReduceValuesToLongTask
5683 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5684 >             MapReduceValuesToLongTask<K,V> nextRight,
5685 >             ObjectToLong<? super V> transformer,
5686 >             long basis,
5687 >             LongByLongToLong reducer) {
5688 >            super(p, b, i, f, t); this.nextRight = nextRight;
5689 >            this.transformer = transformer;
5690 >            this.basis = basis; this.reducer = reducer;
5691 >        }
5692 >        public final Long getRawResult() { return result; }
5693 >        public final void compute() {
5694 >            final ObjectToLong<? super V> transformer;
5695 >            final LongByLongToLong reducer;
5696 >            if ((transformer = this.transformer) != null &&
5697 >                (reducer = this.reducer) != null) {
5698 >                long r = this.basis;
5699 >                for (int i = baseIndex, f, h; batch > 0 &&
5700 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5701 >                    addToPendingCount(1);
5702 >                    (rights = new MapReduceValuesToLongTask<K,V>
5703 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5704 >                      rights, transformer, r, reducer)).fork();
5705 >                }
5706 >                for (Node<K,V> p; (p = advance()) != null; )
5707 >                    r = reducer.apply(r, transformer.apply(p.val));
5708 >                result = r;
5709 >                CountedCompleter<?> c;
5710 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5711 >                    @SuppressWarnings("unchecked") MapReduceValuesToLongTask<K,V>
5712 >                        t = (MapReduceValuesToLongTask<K,V>)c,
5713 >                        s = t.rights;
5714 >                    while (s != null) {
5715 >                        t.result = reducer.apply(t.result, s.result);
5716 >                        s = t.rights = s.nextRight;
5717 >                    }
5718 >                }
5719 >            }
5720 >        }
5721 >    }
5722 >
5723 >    @SuppressWarnings("serial")
5724 >    static final class MapReduceEntriesToLongTask<K,V>
5725 >        extends BulkTask<K,V,Long> {
5726 >        final ObjectToLong<Map.Entry<K,V>> transformer;
5727 >        final LongByLongToLong reducer;
5728 >        final long basis;
5729 >        long result;
5730 >        MapReduceEntriesToLongTask<K,V> rights, nextRight;
5731 >        MapReduceEntriesToLongTask
5732 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5733 >             MapReduceEntriesToLongTask<K,V> nextRight,
5734 >             ObjectToLong<Map.Entry<K,V>> transformer,
5735 >             long basis,
5736 >             LongByLongToLong reducer) {
5737 >            super(p, b, i, f, t); this.nextRight = nextRight;
5738 >            this.transformer = transformer;
5739 >            this.basis = basis; this.reducer = reducer;
5740 >        }
5741 >        public final Long getRawResult() { return result; }
5742 >        public final void compute() {
5743 >            final ObjectToLong<Map.Entry<K,V>> transformer;
5744 >            final LongByLongToLong reducer;
5745 >            if ((transformer = this.transformer) != null &&
5746 >                (reducer = this.reducer) != null) {
5747 >                long r = this.basis;
5748 >                for (int i = baseIndex, f, h; batch > 0 &&
5749 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5750 >                    addToPendingCount(1);
5751 >                    (rights = new MapReduceEntriesToLongTask<K,V>
5752 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5753 >                      rights, transformer, r, reducer)).fork();
5754 >                }
5755 >                for (Node<K,V> p; (p = advance()) != null; )
5756 >                    r = reducer.apply(r, transformer.apply(p));
5757 >                result = r;
5758 >                CountedCompleter<?> c;
5759 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5760 >                    @SuppressWarnings("unchecked") MapReduceEntriesToLongTask<K,V>
5761 >                        t = (MapReduceEntriesToLongTask<K,V>)c,
5762 >                        s = t.rights;
5763 >                    while (s != null) {
5764 >                        t.result = reducer.apply(t.result, s.result);
5765 >                        s = t.rights = s.nextRight;
5766 >                    }
5767 >                }
5768 >            }
5769 >        }
5770 >    }
5771 >
5772 >    @SuppressWarnings("serial")
5773 >    static final class MapReduceMappingsToLongTask<K,V>
5774 >        extends BulkTask<K,V,Long> {
5775 >        final ObjectByObjectToLong<? super K, ? super V> transformer;
5776 >        final LongByLongToLong reducer;
5777 >        final long basis;
5778 >        long result;
5779 >        MapReduceMappingsToLongTask<K,V> rights, nextRight;
5780 >        MapReduceMappingsToLongTask
5781 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5782 >             MapReduceMappingsToLongTask<K,V> nextRight,
5783 >             ObjectByObjectToLong<? super K, ? super V> transformer,
5784 >             long basis,
5785 >             LongByLongToLong reducer) {
5786 >            super(p, b, i, f, t); this.nextRight = nextRight;
5787 >            this.transformer = transformer;
5788 >            this.basis = basis; this.reducer = reducer;
5789 >        }
5790 >        public final Long getRawResult() { return result; }
5791 >        public final void compute() {
5792 >            final ObjectByObjectToLong<? super K, ? super V> transformer;
5793 >            final LongByLongToLong reducer;
5794 >            if ((transformer = this.transformer) != null &&
5795 >                (reducer = this.reducer) != null) {
5796 >                long r = this.basis;
5797 >                for (int i = baseIndex, f, h; batch > 0 &&
5798 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5799 >                    addToPendingCount(1);
5800 >                    (rights = new MapReduceMappingsToLongTask<K,V>
5801 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5802 >                      rights, transformer, r, reducer)).fork();
5803 >                }
5804 >                for (Node<K,V> p; (p = advance()) != null; )
5805 >                    r = reducer.apply(r, transformer.apply(p.key, p.val));
5806 >                result = r;
5807 >                CountedCompleter<?> c;
5808 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5809 >                    @SuppressWarnings("unchecked") MapReduceMappingsToLongTask<K,V>
5810 >                        t = (MapReduceMappingsToLongTask<K,V>)c,
5811 >                        s = t.rights;
5812 >                    while (s != null) {
5813 >                        t.result = reducer.apply(t.result, s.result);
5814 >                        s = t.rights = s.nextRight;
5815 >                    }
5816 >                }
5817 >            }
5818 >        }
5819 >    }
5820 >
5821 >    @SuppressWarnings("serial")
5822 >    static final class MapReduceKeysToIntTask<K,V>
5823 >        extends BulkTask<K,V,Integer> {
5824 >        final ObjectToInt<? super K> transformer;
5825 >        final IntByIntToInt reducer;
5826 >        final int basis;
5827 >        int result;
5828 >        MapReduceKeysToIntTask<K,V> rights, nextRight;
5829 >        MapReduceKeysToIntTask
5830 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5831 >             MapReduceKeysToIntTask<K,V> nextRight,
5832 >             ObjectToInt<? super K> transformer,
5833 >             int basis,
5834 >             IntByIntToInt reducer) {
5835 >            super(p, b, i, f, t); this.nextRight = nextRight;
5836 >            this.transformer = transformer;
5837 >            this.basis = basis; this.reducer = reducer;
5838 >        }
5839 >        public final Integer getRawResult() { return result; }
5840 >        public final void compute() {
5841 >            final ObjectToInt<? super K> transformer;
5842 >            final IntByIntToInt reducer;
5843 >            if ((transformer = this.transformer) != null &&
5844 >                (reducer = this.reducer) != null) {
5845 >                int r = this.basis;
5846 >                for (int i = baseIndex, f, h; batch > 0 &&
5847 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5848 >                    addToPendingCount(1);
5849 >                    (rights = new MapReduceKeysToIntTask<K,V>
5850 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5851 >                      rights, transformer, r, reducer)).fork();
5852 >                }
5853 >                for (Node<K,V> p; (p = advance()) != null; )
5854 >                    r = reducer.apply(r, transformer.apply(p.key));
5855 >                result = r;
5856 >                CountedCompleter<?> c;
5857 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5858 >                    @SuppressWarnings("unchecked") MapReduceKeysToIntTask<K,V>
5859 >                        t = (MapReduceKeysToIntTask<K,V>)c,
5860 >                        s = t.rights;
5861 >                    while (s != null) {
5862 >                        t.result = reducer.apply(t.result, s.result);
5863 >                        s = t.rights = s.nextRight;
5864 >                    }
5865 >                }
5866 >            }
5867 >        }
5868 >    }
5869 >
5870 >    @SuppressWarnings("serial")
5871 >    static final class MapReduceValuesToIntTask<K,V>
5872 >        extends BulkTask<K,V,Integer> {
5873 >        final ObjectToInt<? super V> transformer;
5874 >        final IntByIntToInt reducer;
5875 >        final int basis;
5876 >        int result;
5877 >        MapReduceValuesToIntTask<K,V> rights, nextRight;
5878 >        MapReduceValuesToIntTask
5879 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5880 >             MapReduceValuesToIntTask<K,V> nextRight,
5881 >             ObjectToInt<? super V> transformer,
5882 >             int basis,
5883 >             IntByIntToInt reducer) {
5884 >            super(p, b, i, f, t); this.nextRight = nextRight;
5885 >            this.transformer = transformer;
5886 >            this.basis = basis; this.reducer = reducer;
5887 >        }
5888 >        public final Integer getRawResult() { return result; }
5889 >        public final void compute() {
5890 >            final ObjectToInt<? super V> transformer;
5891 >            final IntByIntToInt reducer;
5892 >            if ((transformer = this.transformer) != null &&
5893 >                (reducer = this.reducer) != null) {
5894 >                int r = this.basis;
5895 >                for (int i = baseIndex, f, h; batch > 0 &&
5896 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5897 >                    addToPendingCount(1);
5898 >                    (rights = new MapReduceValuesToIntTask<K,V>
5899 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5900 >                      rights, transformer, r, reducer)).fork();
5901 >                }
5902 >                for (Node<K,V> p; (p = advance()) != null; )
5903 >                    r = reducer.apply(r, transformer.apply(p.val));
5904 >                result = r;
5905 >                CountedCompleter<?> c;
5906 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5907 >                    @SuppressWarnings("unchecked") MapReduceValuesToIntTask<K,V>
5908 >                        t = (MapReduceValuesToIntTask<K,V>)c,
5909 >                        s = t.rights;
5910 >                    while (s != null) {
5911 >                        t.result = reducer.apply(t.result, s.result);
5912 >                        s = t.rights = s.nextRight;
5913 >                    }
5914 >                }
5915 >            }
5916 >        }
5917 >    }
5918 >
5919 >    @SuppressWarnings("serial")
5920 >    static final class MapReduceEntriesToIntTask<K,V>
5921 >        extends BulkTask<K,V,Integer> {
5922 >        final ObjectToInt<Map.Entry<K,V>> transformer;
5923 >        final IntByIntToInt reducer;
5924 >        final int basis;
5925 >        int result;
5926 >        MapReduceEntriesToIntTask<K,V> rights, nextRight;
5927 >        MapReduceEntriesToIntTask
5928 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5929 >             MapReduceEntriesToIntTask<K,V> nextRight,
5930 >             ObjectToInt<Map.Entry<K,V>> transformer,
5931 >             int basis,
5932 >             IntByIntToInt reducer) {
5933 >            super(p, b, i, f, t); this.nextRight = nextRight;
5934 >            this.transformer = transformer;
5935 >            this.basis = basis; this.reducer = reducer;
5936 >        }
5937 >        public final Integer getRawResult() { return result; }
5938 >        public final void compute() {
5939 >            final ObjectToInt<Map.Entry<K,V>> transformer;
5940 >            final IntByIntToInt reducer;
5941 >            if ((transformer = this.transformer) != null &&
5942 >                (reducer = this.reducer) != null) {
5943 >                int r = this.basis;
5944 >                for (int i = baseIndex, f, h; batch > 0 &&
5945 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5946 >                    addToPendingCount(1);
5947 >                    (rights = new MapReduceEntriesToIntTask<K,V>
5948 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5949 >                      rights, transformer, r, reducer)).fork();
5950 >                }
5951 >                for (Node<K,V> p; (p = advance()) != null; )
5952 >                    r = reducer.apply(r, transformer.apply(p));
5953 >                result = r;
5954 >                CountedCompleter<?> c;
5955 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5956 >                    @SuppressWarnings("unchecked") MapReduceEntriesToIntTask<K,V>
5957 >                        t = (MapReduceEntriesToIntTask<K,V>)c,
5958 >                        s = t.rights;
5959 >                    while (s != null) {
5960 >                        t.result = reducer.apply(t.result, s.result);
5961 >                        s = t.rights = s.nextRight;
5962 >                    }
5963 >                }
5964 >            }
5965 >        }
5966 >    }
5967 >
5968 >    @SuppressWarnings("serial")
5969 >    static final class MapReduceMappingsToIntTask<K,V>
5970 >        extends BulkTask<K,V,Integer> {
5971 >        final ObjectByObjectToInt<? super K, ? super V> transformer;
5972 >        final IntByIntToInt reducer;
5973 >        final int basis;
5974 >        int result;
5975 >        MapReduceMappingsToIntTask<K,V> rights, nextRight;
5976 >        MapReduceMappingsToIntTask
5977 >            (BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5978 >             MapReduceMappingsToIntTask<K,V> nextRight,
5979 >             ObjectByObjectToInt<? super K, ? super V> transformer,
5980 >             int basis,
5981 >             IntByIntToInt reducer) {
5982 >            super(p, b, i, f, t); this.nextRight = nextRight;
5983 >            this.transformer = transformer;
5984 >            this.basis = basis; this.reducer = reducer;
5985 >        }
5986 >        public final Integer getRawResult() { return result; }
5987 >        public final void compute() {
5988 >            final ObjectByObjectToInt<? super K, ? super V> transformer;
5989 >            final IntByIntToInt reducer;
5990 >            if ((transformer = this.transformer) != null &&
5991 >                (reducer = this.reducer) != null) {
5992 >                int r = this.basis;
5993 >                for (int i = baseIndex, f, h; batch > 0 &&
5994 >                         (h = ((f = baseLimit) + i) >>> 1) > i;) {
5995 >                    addToPendingCount(1);
5996 >                    (rights = new MapReduceMappingsToIntTask<K,V>
5997 >                     (this, batch >>>= 1, baseLimit = h, f, tab,
5998 >                      rights, transformer, r, reducer)).fork();
5999 >                }
6000 >                for (Node<K,V> p; (p = advance()) != null; )
6001 >                    r = reducer.apply(r, transformer.apply(p.key, p.val));
6002 >                result = r;
6003 >                CountedCompleter<?> c;
6004 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6005 >                    @SuppressWarnings("unchecked") MapReduceMappingsToIntTask<K,V>
6006 >                        t = (MapReduceMappingsToIntTask<K,V>)c,
6007 >                        s = t.rights;
6008 >                    while (s != null) {
6009 >                        t.result = reducer.apply(t.result, s.result);
6010 >                        s = t.rights = s.nextRight;
6011 >                    }
6012 >                }
6013 >            }
6014 >        }
6015 >    }
6016 >
6017 >    /* ---------------- Counters -------------- */
6018 >
6019 >    // Adapted from LongAdder and Striped64.
6020 >    // See their internal docs for explanation.
6021 >
6022 >    // A padded cell for distributing counts
6023 >    static final class CounterCell {
6024 >        volatile long p0, p1, p2, p3, p4, p5, p6;
6025 >        volatile long value;
6026 >        volatile long q0, q1, q2, q3, q4, q5, q6;
6027 >        CounterCell(long x) { value = x; }
6028 >    }
6029 >
6030 >    /**
6031 >     * Holder for the thread-local hash code determining which
6032 >     * CounterCell to use. The code is initialized via the
6033 >     * counterHashCodeGenerator, but may be moved upon collisions.
6034 >     */
6035 >    static final class CounterHashCode {
6036 >        int code;
6037 >    }
6038 >
6039 >    /**
6040 >     * Generates initial value for per-thread CounterHashCodes.
6041 >     */
6042 >    static final AtomicInteger counterHashCodeGenerator = new AtomicInteger();
6043 >
6044 >    /**
6045 >     * Increment for counterHashCodeGenerator. See class ThreadLocal
6046 >     * for explanation.
6047 >     */
6048 >    static final int SEED_INCREMENT = 0x61c88647;
6049 >
6050 >    /**
6051 >     * Per-thread counter hash codes. Shared across all instances.
6052 >     */
6053 >    static final ThreadLocal<CounterHashCode> threadCounterHashCode =
6054 >        new ThreadLocal<CounterHashCode>();
6055 >
6056 >
6057 >    final long sumCount() {
6058 >        CounterCell[] as = counterCells; CounterCell a;
6059 >        long sum = baseCount;
6060 >        if (as != null) {
6061 >            for (int i = 0; i < as.length; ++i) {
6062 >                if ((a = as[i]) != null)
6063 >                    sum += a.value;
6064 >            }
6065 >        }
6066 >        return sum;
6067 >    }
6068 >
6069 >    // See LongAdder version for explanation
6070 >    private final void fullAddCount(long x, CounterHashCode hc,
6071 >                                    boolean wasUncontended) {
6072 >        int h;
6073 >        if (hc == null) {
6074 >            hc = new CounterHashCode();
6075 >            int s = counterHashCodeGenerator.addAndGet(SEED_INCREMENT);
6076 >            h = hc.code = (s == 0) ? 1 : s; // Avoid zero
6077 >            threadCounterHashCode.set(hc);
6078 >        }
6079 >        else
6080 >            h = hc.code;
6081 >        boolean collide = false;                // True if last slot nonempty
6082 >        for (;;) {
6083 >            CounterCell[] as; CounterCell a; int n; long v;
6084 >            if ((as = counterCells) != null && (n = as.length) > 0) {
6085 >                if ((a = as[(n - 1) & h]) == null) {
6086 >                    if (cellsBusy == 0) {            // Try to attach new Cell
6087 >                        CounterCell r = new CounterCell(x); // Optimistic create
6088 >                        if (cellsBusy == 0 &&
6089 >                            U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
6090 >                            boolean created = false;
6091 >                            try {               // Recheck under lock
6092 >                                CounterCell[] rs; int m, j;
6093 >                                if ((rs = counterCells) != null &&
6094 >                                    (m = rs.length) > 0 &&
6095 >                                    rs[j = (m - 1) & h] == null) {
6096 >                                    rs[j] = r;
6097 >                                    created = true;
6098 >                                }
6099 >                            } finally {
6100 >                                cellsBusy = 0;
6101 >                            }
6102 >                            if (created)
6103 >                                break;
6104 >                            continue;           // Slot is now non-empty
6105                          }
3267                        table = tab;
3268                        counter.add(size);
3269                        sc = n - (n >>> 2);
6106                      }
6107 <                } finally {
3272 <                    sizeCtl = sc;
6107 >                    collide = false;
6108                  }
6109 <                if (collide) { // rescan and convert to TreeBins
6110 <                    Node[] tab = table;
6111 <                    for (int i = 0; i < tab.length; ++i) {
6112 <                        int c = 0;
6113 <                        for (Node e = tabAt(tab, i); e != null; e = e.next) {
6114 <                            if (++c > TREE_THRESHOLD &&
6115 <                                (e.key instanceof Comparable)) {
6116 <                                replaceWithTreeBin(tab, i, e.key);
6117 <                                break;
6118 <                            }
6109 >                else if (!wasUncontended)       // CAS already known to fail
6110 >                    wasUncontended = true;      // Continue after rehash
6111 >                else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
6112 >                    break;
6113 >                else if (counterCells != as || n >= NCPU)
6114 >                    collide = false;            // At max size or stale
6115 >                else if (!collide)
6116 >                    collide = true;
6117 >                else if (cellsBusy == 0 &&
6118 >                         U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
6119 >                    try {
6120 >                        if (counterCells == as) {// Expand table unless stale
6121 >                            CounterCell[] rs = new CounterCell[n << 1];
6122 >                            for (int i = 0; i < n; ++i)
6123 >                                rs[i] = as[i];
6124 >                            counterCells = rs;
6125                          }
6126 +                    } finally {
6127 +                        cellsBusy = 0;
6128                      }
6129 +                    collide = false;
6130 +                    continue;                   // Retry with expanded table
6131                  }
6132 <            }
6133 <            if (!init) { // Can only happen if unsafely published.
6134 <                while (p != null) {
6135 <                    internalPut(p.key, p.val);
6136 <                    p = p.next;
6132 >                h ^= h << 13;                   // Rehash
6133 >                h ^= h >>> 17;
6134 >                h ^= h << 5;
6135 >            }
6136 >            else if (cellsBusy == 0 && counterCells == as &&
6137 >                     U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
6138 >                boolean init = false;
6139 >                try {                           // Initialize table
6140 >                    if (counterCells == as) {
6141 >                        CounterCell[] rs = new CounterCell[2];
6142 >                        rs[h & 1] = new CounterCell(x);
6143 >                        counterCells = rs;
6144 >                        init = true;
6145 >                    }
6146 >                } finally {
6147 >                    cellsBusy = 0;
6148                  }
6149 +                if (init)
6150 +                    break;
6151              }
6152 +            else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
6153 +                break;                          // Fall back on using base
6154          }
6155 +        hc.code = h;                            // Record index for next time
6156      }
6157  
6158      // Unsafe mechanics
6159 <    private static final sun.misc.Unsafe UNSAFE;
6160 <    private static final long counterOffset;
6161 <    private static final long sizeCtlOffset;
6159 >    private static final sun.misc.Unsafe U;
6160 >    private static final long SIZECTL;
6161 >    private static final long TRANSFERINDEX;
6162 >    private static final long TRANSFERORIGIN;
6163 >    private static final long BASECOUNT;
6164 >    private static final long CELLSBUSY;
6165 >    private static final long CELLVALUE;
6166      private static final long ABASE;
6167      private static final int ASHIFT;
6168  
6169      static {
3305        int ss;
6170          try {
6171 <            UNSAFE = getUnsafe();
6171 >            U = getUnsafe();
6172              Class<?> k = ConcurrentHashMapV8.class;
6173 <            counterOffset = UNSAFE.objectFieldOffset
3310 <                (k.getDeclaredField("counter"));
3311 <            sizeCtlOffset = UNSAFE.objectFieldOffset
6173 >            SIZECTL = U.objectFieldOffset
6174                  (k.getDeclaredField("sizeCtl"));
6175 <            Class<?> sc = Node[].class;
6176 <            ABASE = UNSAFE.arrayBaseOffset(sc);
6177 <            ss = UNSAFE.arrayIndexScale(sc);
6175 >            TRANSFERINDEX = U.objectFieldOffset
6176 >                (k.getDeclaredField("transferIndex"));
6177 >            TRANSFERORIGIN = U.objectFieldOffset
6178 >                (k.getDeclaredField("transferOrigin"));
6179 >            BASECOUNT = U.objectFieldOffset
6180 >                (k.getDeclaredField("baseCount"));
6181 >            CELLSBUSY = U.objectFieldOffset
6182 >                (k.getDeclaredField("cellsBusy"));
6183 >            Class<?> ck = CounterCell.class;
6184 >            CELLVALUE = U.objectFieldOffset
6185 >                (ck.getDeclaredField("value"));
6186 >            Class<?> ak = Node[].class;
6187 >            ABASE = U.arrayBaseOffset(ak);
6188 >            int scale = U.arrayIndexScale(ak);
6189 >            if ((scale & (scale - 1)) != 0)
6190 >                throw new Error("data type scale not a power of two");
6191 >            ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6192          } catch (Exception e) {
6193              throw new Error(e);
6194          }
3319        if ((ss & (ss-1)) != 0)
3320            throw new Error("data type scale not a power of two");
3321        ASHIFT = 31 - Integer.numberOfLeadingZeros(ss);
6195      }
6196  
6197      /**
# Line 3331 | Line 6204 | public class ConcurrentHashMapV8<K, V>
6204      private static sun.misc.Unsafe getUnsafe() {
6205          try {
6206              return sun.misc.Unsafe.getUnsafe();
6207 <        } catch (SecurityException se) {
6208 <            try {
6209 <                return java.security.AccessController.doPrivileged
6210 <                    (new java.security
6211 <                     .PrivilegedExceptionAction<sun.misc.Unsafe>() {
6212 <                        public sun.misc.Unsafe run() throws Exception {
6213 <                            java.lang.reflect.Field f = sun.misc
6214 <                                .Unsafe.class.getDeclaredField("theUnsafe");
6215 <                            f.setAccessible(true);
6216 <                            return (sun.misc.Unsafe) f.get(null);
6217 <                        }});
6218 <            } catch (java.security.PrivilegedActionException e) {
6219 <                throw new RuntimeException("Could not initialize intrinsics",
6220 <                                           e.getCause());
6221 <            }
6207 >        } catch (SecurityException tryReflectionInstead) {}
6208 >        try {
6209 >            return java.security.AccessController.doPrivileged
6210 >            (new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
6211 >                public sun.misc.Unsafe run() throws Exception {
6212 >                    Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
6213 >                    for (java.lang.reflect.Field f : k.getDeclaredFields()) {
6214 >                        f.setAccessible(true);
6215 >                        Object x = f.get(null);
6216 >                        if (k.isInstance(x))
6217 >                            return k.cast(x);
6218 >                    }
6219 >                    throw new NoSuchFieldError("the Unsafe");
6220 >                }});
6221 >        } catch (java.security.PrivilegedActionException e) {
6222 >            throw new RuntimeException("Could not initialize intrinsics",
6223 >                                       e.getCause());
6224          }
6225      }
3351
6226   }

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