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Comparing jsr166/src/jsr166e/ConcurrentHashMapV8.java (file contents):
Revision 1.19 by jsr166, Sat Sep 10 01:38:28 2011 UTC vs.
Revision 1.69 by jsr166, Sun Oct 21 06:14:11 2012 UTC

# Line 6 | Line 6
6  
7   package jsr166e;
8   import jsr166e.LongAdder;
9 + import jsr166e.ForkJoinPool;
10 + import jsr166e.ForkJoinTask;
11 +
12 + import java.util.Comparator;
13 + import java.util.Arrays;
14   import java.util.Map;
15   import java.util.Set;
16   import java.util.Collection;
# Line 19 | Line 24 | import java.util.Enumeration;
24   import java.util.ConcurrentModificationException;
25   import java.util.NoSuchElementException;
26   import java.util.concurrent.ConcurrentMap;
27 + import java.util.concurrent.ThreadLocalRandom;
28 + import java.util.concurrent.locks.LockSupport;
29 + import java.util.concurrent.locks.AbstractQueuedSynchronizer;
30 + import java.util.concurrent.atomic.AtomicReference;
31 +
32   import java.io.Serializable;
33  
34   /**
# Line 37 | Line 47 | import java.io.Serializable;
47   * block, so may overlap with update operations (including {@code put}
48   * and {@code remove}). Retrievals reflect the results of the most
49   * recently <em>completed</em> update operations holding upon their
50 < * onset.  For aggregate operations such as {@code putAll} and {@code
51 < * clear}, concurrent retrievals may reflect insertion or removal of
52 < * only some entries.  Similarly, Iterators and Enumerations return
53 < * elements reflecting the state of the hash table at some point at or
54 < * since the creation of the iterator/enumeration.  They do
55 < * <em>not</em> throw {@link ConcurrentModificationException}.
56 < * However, iterators are designed to be used by only one thread at a
57 < * time.  Bear in mind that the results of aggregate status methods
58 < * including {@code size}, {@code isEmpty}, and {@code containsValue}
59 < * are typically useful only when a map is not undergoing concurrent
60 < * updates in other threads.  Otherwise the results of these methods
61 < * reflect transient states that may be adequate for monitoring
62 < * or estimation purposes, but not for program control.
50 > * onset. (More formally, an update operation for a given key bears a
51 > * <em>happens-before</em> relation with any (non-null) retrieval for
52 > * that key reporting the updated value.)  For aggregate operations
53 > * such as {@code putAll} and {@code clear}, concurrent retrievals may
54 > * reflect insertion or removal of only some entries.  Similarly,
55 > * Iterators and Enumerations return elements reflecting the state of
56 > * the hash table at some point at or since the creation of the
57 > * iterator/enumeration.  They do <em>not</em> throw {@link
58 > * ConcurrentModificationException}.  However, iterators are designed
59 > * to be used by only one thread at a time.  Bear in mind that the
60 > * results of aggregate status methods including {@code size}, {@code
61 > * isEmpty}, and {@code containsValue} are typically useful only when
62 > * a map is not undergoing concurrent updates in other threads.
63 > * Otherwise the results of these methods reflect transient states
64 > * that may be adequate for monitoring or estimation purposes, but not
65 > * for program control.
66   *
67   * <p> The table is dynamically expanded when there are too many
68   * collisions (i.e., keys that have distinct hash codes but fall into
69   * the same slot modulo the table size), with the expected average
70 < * effect of maintaining roughly two bins per mapping. There may be
71 < * much variance around this average as mappings are added and
72 < * removed, but overall, this maintains a commonly accepted time/space
73 < * tradeoff for hash tables.  However, resizing this or any other kind
74 < * of hash table may be a relatively slow operation. When possible, it
75 < * is a good idea to provide a size estimate as an optional {@code
70 > * effect of maintaining roughly two bins per mapping (corresponding
71 > * to a 0.75 load factor threshold for resizing). There may be much
72 > * variance around this average as mappings are added and removed, but
73 > * overall, this maintains a commonly accepted time/space tradeoff for
74 > * hash tables.  However, resizing this or any other kind of hash
75 > * table may be a relatively slow operation. When possible, it is a
76 > * good idea to provide a size estimate as an optional {@code
77   * initialCapacity} constructor argument. An additional optional
78   * {@code loadFactor} constructor argument provides a further means of
79   * customizing initial table capacity by specifying the table density
# Line 68 | Line 82 | import java.io.Serializable;
82   * versions of this class, constructors may optionally specify an
83   * expected {@code concurrencyLevel} as an additional hint for
84   * internal sizing.  Note that using many keys with exactly the same
85 < * {@code hashCode{}} is a sure way to slow down performance of any
85 > * {@code hashCode()} is a sure way to slow down performance of any
86   * hash table.
87   *
88   * <p>This class and its views and iterators implement all of the
# Line 83 | Line 97 | import java.io.Serializable;
97   * Java Collections Framework</a>.
98   *
99   * <p><em>jsr166e note: This class is a candidate replacement for
100 < * java.util.concurrent.ConcurrentHashMap.<em>
100 > * java.util.concurrent.ConcurrentHashMap.  During transition, this
101 > * class declares and uses nested functional interfaces with different
102 > * names but the same forms as those expected for JDK8.<em>
103   *
104 < * @since 1.8
104 > * @since 1.5
105   * @author Doug Lea
106   * @param <K> the type of keys maintained by this map
107   * @param <V> the type of mapped values
108   */
109   public class ConcurrentHashMapV8<K, V>
110 <        implements ConcurrentMap<K, V>, Serializable {
110 >    implements ConcurrentMap<K, V>, Serializable {
111      private static final long serialVersionUID = 7249069246763182397L;
112  
113      /**
114 <     * A function computing a mapping from the given key to a value,
115 <     * or {@code null} if there is no mapping. This is a place-holder
116 <     * for an upcoming JDK8 interface.
117 <     */
118 <    public static interface MappingFunction<K, V> {
119 <        /**
120 <         * Returns a value for the given key, or null if there is no
121 <         * mapping. If this function throws an (unchecked) exception,
122 <         * the exception is rethrown to its caller, and no mapping is
123 <         * recorded.  Because this function is invoked within
124 <         * atomicity control, the computation should be short and
125 <         * simple. The most common usage is to construct a new object
126 <         * serving as an initial mapped value.
114 >     * A partitionable iterator. A Spliterator can be traversed
115 >     * directly, but can also be partitioned (before traversal) by
116 >     * creating another Spliterator that covers a non-overlapping
117 >     * portion of the elements, and so may be amenable to parallel
118 >     * execution.
119 >     *
120 >     * <p> This interface exports a subset of expected JDK8
121 >     * functionality.
122 >     *
123 >     * <p>Sample usage: Here is one (of the several) ways to compute
124 >     * the sum of the values held in a map using the ForkJoin
125 >     * framework. As illustrated here, Spliterators are well suited to
126 >     * designs in which a task repeatedly splits off half its work
127 >     * into forked subtasks until small enough to process directly,
128 >     * and then joins these subtasks. Variants of this style can also
129 >     * be used in completion-based designs.
130 >     *
131 >     * <pre>
132 >     * {@code ConcurrentHashMapV8<String, Long> m = ...
133 >     * // split as if have 8 * parallelism, for load balance
134 >     * int n = m.size();
135 >     * int p = aForkJoinPool.getParallelism() * 8;
136 >     * int split = (n < p)? n : p;
137 >     * long sum = aForkJoinPool.invoke(new SumValues(m.valueSpliterator(), split, null));
138 >     * // ...
139 >     * static class SumValues extends RecursiveTask<Long> {
140 >     *   final Spliterator<Long> s;
141 >     *   final int split;             // split while > 1
142 >     *   final SumValues nextJoin;    // records forked subtasks to join
143 >     *   SumValues(Spliterator<Long> s, int depth, SumValues nextJoin) {
144 >     *     this.s = s; this.depth = depth; this.nextJoin = nextJoin;
145 >     *   }
146 >     *   public Long compute() {
147 >     *     long sum = 0;
148 >     *     SumValues subtasks = null; // fork subtasks
149 >     *     for (int s = split >>> 1; s > 0; s >>>= 1)
150 >     *       (subtasks = new SumValues(s.split(), s, subtasks)).fork();
151 >     *     while (s.hasNext())        // directly process remaining elements
152 >     *       sum += s.next();
153 >     *     for (SumValues t = subtasks; t != null; t = t.nextJoin)
154 >     *       sum += t.join();         // collect subtask results
155 >     *     return sum;
156 >     *   }
157 >     * }
158 >     * }</pre>
159 >     */
160 >    public static interface Spliterator<T> extends Iterator<T> {
161 >        /**
162 >         * Returns a Spliterator covering approximately half of the
163 >         * elements, guaranteed not to overlap with those subsequently
164 >         * returned by this Spliterator.  After invoking this method,
165 >         * the current Spliterator will <em>not</em> produce any of
166 >         * the elements of the returned Spliterator, but the two
167 >         * Spliterators together will produce all of the elements that
168 >         * would have been produced by this Spliterator had this
169 >         * method not been called. The exact number of elements
170 >         * produced by the returned Spliterator is not guaranteed, and
171 >         * may be zero (i.e., with {@code hasNext()} reporting {@code
172 >         * false}) if this Spliterator cannot be further split.
173           *
174 <         * @param key the (non-null) key
175 <         * @return a value, or null if none
174 >         * @return a Spliterator covering approximately half of the
175 >         * elements
176 >         * @throws IllegalStateException if this Spliterator has
177 >         * already commenced traversing elements
178           */
179 <        V map(K key);
179 >        Spliterator<T> split();
180      }
181  
182      /*
# Line 121 | Line 185 | public class ConcurrentHashMapV8<K, V>
185       * The primary design goal of this hash table is to maintain
186       * concurrent readability (typically method get(), but also
187       * iterators and related methods) while minimizing update
188 <     * contention.
188 >     * contention. Secondary goals are to keep space consumption about
189 >     * the same or better than java.util.HashMap, and to support high
190 >     * initial insertion rates on an empty table by many threads.
191       *
192       * Each key-value mapping is held in a Node.  Because Node fields
193       * can contain special values, they are defined using plain Object
# Line 129 | Line 195 | public class ConcurrentHashMapV8<K, V>
195       * work off Object types. And similarly, so do the internal
196       * methods of auxiliary iterator and view classes.  All public
197       * generic typed methods relay in/out of these internal methods,
198 <     * supplying null-checks and casts as needed.
198 >     * supplying null-checks and casts as needed. This also allows
199 >     * many of the public methods to be factored into a smaller number
200 >     * of internal methods (although sadly not so for the five
201 >     * variants of put-related operations). The validation-based
202 >     * approach explained below leads to a lot of code sprawl because
203 >     * retry-control precludes factoring into smaller methods.
204       *
205       * The table is lazily initialized to a power-of-two size upon the
206 <     * first insertion.  Each bin in the table contains a list of
207 <     * Nodes (most often, zero or one Node).  Table accesses require
208 <     * volatile/atomic reads, writes, and CASes.  Because there is no
209 <     * other way to arrange this without adding further indirections,
210 <     * we use intrinsics (sun.misc.Unsafe) operations.  The lists of
211 <     * nodes within bins are always accurately traversable under
212 <     * volatile reads, so long as lookups check hash code and
213 <     * non-nullness of value before checking key equality. (All valid
214 <     * hash codes are nonnegative. Negative values are reserved for
215 <     * special forwarding nodes; see below.)
206 >     * first insertion.  Each bin in the table normally contains a
207 >     * list of Nodes (most often, the list has only zero or one Node).
208 >     * Table accesses require volatile/atomic reads, writes, and
209 >     * CASes.  Because there is no other way to arrange this without
210 >     * adding further indirections, we use intrinsics
211 >     * (sun.misc.Unsafe) operations.  The lists of nodes within bins
212 >     * are always accurately traversable under volatile reads, so long
213 >     * as lookups check hash code and non-nullness of value before
214 >     * checking key equality.
215 >     *
216 >     * We use the top two bits of Node hash fields for control
217 >     * purposes -- they are available anyway because of addressing
218 >     * constraints.  As explained further below, these top bits are
219 >     * used as follows:
220 >     *  00 - Normal
221 >     *  01 - Locked
222 >     *  11 - Locked and may have a thread waiting for lock
223 >     *  10 - Node is a forwarding node
224 >     *
225 >     * The lower 30 bits of each Node's hash field contain a
226 >     * transformation of the key's hash code, except for forwarding
227 >     * nodes, for which the lower bits are zero (and so always have
228 >     * hash field == MOVED).
229       *
230 <     * Insertion (via put or putIfAbsent) of the first node in an
230 >     * Insertion (via put or its variants) of the first node in an
231       * empty bin is performed by just CASing it to the bin.  This is
232 <     * on average by far the most common case for put operations.
233 <     * Other update operations (insert, delete, and replace) require
234 <     * locks.  We do not want to waste the space required to associate
235 <     * a distinct lock object with each bin, so instead use the first
236 <     * node of a bin list itself as a lock, using plain "synchronized"
237 <     * locks. These save space and we can live with block-structured
238 <     * lock/unlock operations. Using the first node of a list as a
239 <     * lock does not by itself suffice though: When a node is locked,
240 <     * any update must first validate that it is still the first node,
241 <     * and retry if not. Because new nodes are always appended to
242 <     * lists, once a node is first in a bin, it remains first until
243 <     * deleted or the bin becomes invalidated.  However, operations
244 <     * that only conditionally update can and sometimes do inspect
245 <     * nodes until the point of update. This is a converse of sorts to
246 <     * the lazy locking technique described by Herlihy & Shavit.
232 >     * by far the most common case for put operations under most
233 >     * key/hash distributions.  Other update operations (insert,
234 >     * delete, and replace) require locks.  We do not want to waste
235 >     * the space required to associate a distinct lock object with
236 >     * each bin, so instead use the first node of a bin list itself as
237 >     * a lock. Blocking support for these locks relies on the builtin
238 >     * "synchronized" monitors.  However, we also need a tryLock
239 >     * construction, so we overlay these by using bits of the Node
240 >     * hash field for lock control (see above), and so normally use
241 >     * builtin monitors only for blocking and signalling using
242 >     * wait/notifyAll constructions. See Node.tryAwaitLock.
243 >     *
244 >     * Using the first node of a list as a lock does not by itself
245 >     * suffice though: When a node is locked, any update must first
246 >     * validate that it is still the first node after locking it, and
247 >     * retry if not. Because new nodes are always appended to lists,
248 >     * once a node is first in a bin, it remains first until deleted
249 >     * or the bin becomes invalidated (upon resizing).  However,
250 >     * operations that only conditionally update may inspect nodes
251 >     * until the point of update. This is a converse of sorts to the
252 >     * lazy locking technique described by Herlihy & Shavit.
253       *
254 <     * The main disadvantage of this approach is that most update
254 >     * The main disadvantage of per-bin locks is that other update
255       * operations on other nodes in a bin list protected by the same
256       * lock can stall, for example when user equals() or mapping
257 <     * functions take a long time.  However, statistically, this is
258 <     * not a common enough problem to outweigh the time/space overhead
259 <     * of alternatives: Under random hash codes, the frequency of
170 <     * nodes in bins follows a Poisson distribution
257 >     * functions take a long time.  However, statistically, under
258 >     * random hash codes, this is not a common problem.  Ideally, the
259 >     * frequency of nodes in bins follows a Poisson distribution
260       * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
261       * parameter of about 0.5 on average, given the resizing threshold
262       * of 0.75, although with a large variance because of resizing
263       * granularity. Ignoring variance, the expected occurrences of
264       * list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
265 <     * first few values are:
265 >     * first values are:
266       *
267 <     * 0:    0.607
268 <     * 1:    0.303
269 <     * 2:    0.076
270 <     * 3:    0.012
271 <     * more: 0.002
267 >     * 0:    0.60653066
268 >     * 1:    0.30326533
269 >     * 2:    0.07581633
270 >     * 3:    0.01263606
271 >     * 4:    0.00157952
272 >     * 5:    0.00015795
273 >     * 6:    0.00001316
274 >     * 7:    0.00000094
275 >     * 8:    0.00000006
276 >     * more: less than 1 in ten million
277       *
278       * Lock contention probability for two threads accessing distinct
279 <     * elements is roughly 1 / (8 * #elements).  Function "spread"
280 <     * performs hashCode randomization that improves the likelihood
281 <     * that these assumptions hold unless users define exactly the
282 <     * same value for too many hashCodes.
283 <     *
284 <     * The table is resized when occupancy exceeds a threshold.  Only
285 <     * a single thread performs the resize (using field "resizing", to
286 <     * arrange exclusion), but the table otherwise remains usable for
287 <     * reads and updates. Resizing proceeds by transferring bins, one
288 <     * by one, from the table to the next table.  Upon transfer, the
289 <     * old table bin contains only a special forwarding node (with
290 <     * negative hash field) that contains the next table as its
291 <     * key. On encountering a forwarding node, access and update
292 <     * operations restart, using the new table. To ensure concurrent
293 <     * readability of traversals, transfers must proceed from the last
294 <     * bin (table.length - 1) up towards the first.  Upon seeing a
295 <     * forwarding node, traversals (see class InternalIterator)
296 <     * arrange to move to the new table for the rest of the traversal
297 <     * without revisiting nodes.  This constrains bin transfers to a
298 <     * particular order, and so can block indefinitely waiting for the
299 <     * next lock, and other threads cannot help with the transfer.
300 <     * However, expected stalls are infrequent enough to not warrant
301 <     * the additional overhead of access and iteration schemes that
302 <     * could admit out-of-order or concurrent bin transfers.
303 <     *
304 <     * This traversal scheme also applies to partial traversals of
305 <     * ranges of bins (via an alternate InternalIterator constructor)
306 <     * to support partitioned aggregate operations (that are not
307 <     * otherwise implemented yet).  Also, read-only operations give up
308 <     * if ever forwarded to a null table, which provides support for
309 <     * shutdown-style clearing, which is also not currently
310 <     * implemented.
279 >     * elements is roughly 1 / (8 * #elements) under random hashes.
280 >     *
281 >     * Actual hash code distributions encountered in practice
282 >     * sometimes deviate significantly from uniform randomness.  This
283 >     * includes the case when N > (1<<30), so some keys MUST collide.
284 >     * Similarly for dumb or hostile usages in which multiple keys are
285 >     * designed to have identical hash codes. Also, although we guard
286 >     * against the worst effects of this (see method spread), sets of
287 >     * hashes may differ only in bits that do not impact their bin
288 >     * index for a given power-of-two mask.  So we use a secondary
289 >     * strategy that applies when the number of nodes in a bin exceeds
290 >     * a threshold, and at least one of the keys implements
291 >     * Comparable.  These TreeBins use a balanced tree to hold nodes
292 >     * (a specialized form of red-black trees), bounding search time
293 >     * to O(log N).  Each search step in a TreeBin is around twice as
294 >     * slow as in a regular list, but given that N cannot exceed
295 >     * (1<<64) (before running out of addresses) this bounds search
296 >     * steps, lock hold times, etc, to reasonable constants (roughly
297 >     * 100 nodes inspected per operation worst case) so long as keys
298 >     * are Comparable (which is very common -- String, Long, etc).
299 >     * TreeBin nodes (TreeNodes) also maintain the same "next"
300 >     * traversal pointers as regular nodes, so can be traversed in
301 >     * iterators in the same way.
302 >     *
303 >     * The table is resized when occupancy exceeds a percentage
304 >     * threshold (nominally, 0.75, but see below).  Only a single
305 >     * thread performs the resize (using field "sizeCtl", to arrange
306 >     * exclusion), but the table otherwise remains usable for reads
307 >     * and updates. Resizing proceeds by transferring bins, one by
308 >     * one, from the table to the next table.  Because we are using
309 >     * power-of-two expansion, the elements from each bin must either
310 >     * stay at same index, or move with a power of two offset. We
311 >     * eliminate unnecessary node creation by catching cases where old
312 >     * nodes can be reused because their next fields won't change.  On
313 >     * average, only about one-sixth of them need cloning when a table
314 >     * doubles. The nodes they replace will be garbage collectable as
315 >     * soon as they are no longer referenced by any reader thread that
316 >     * may be in the midst of concurrently traversing table.  Upon
317 >     * transfer, the old table bin contains only a special forwarding
318 >     * node (with hash field "MOVED") that contains the next table as
319 >     * its key. On encountering a forwarding node, access and update
320 >     * operations restart, using the new table.
321 >     *
322 >     * Each bin transfer requires its bin lock. However, unlike other
323 >     * cases, a transfer can skip a bin if it fails to acquire its
324 >     * lock, and revisit it later (unless it is a TreeBin). Method
325 >     * rebuild maintains a buffer of TRANSFER_BUFFER_SIZE bins that
326 >     * have been skipped because of failure to acquire a lock, and
327 >     * blocks only if none are available (i.e., only very rarely).
328 >     * The transfer operation must also ensure that all accessible
329 >     * bins in both the old and new table are usable by any traversal.
330 >     * When there are no lock acquisition failures, this is arranged
331 >     * simply by proceeding from the last bin (table.length - 1) up
332 >     * towards the first.  Upon seeing a forwarding node, traversals
333 >     * (see class Iter) arrange to move to the new table
334 >     * without revisiting nodes.  However, when any node is skipped
335 >     * during a transfer, all earlier table bins may have become
336 >     * visible, so are initialized with a reverse-forwarding node back
337 >     * to the old table until the new ones are established. (This
338 >     * sometimes requires transiently locking a forwarding node, which
339 >     * is possible under the above encoding.) These more expensive
340 >     * mechanics trigger only when necessary.
341 >     *
342 >     * The traversal scheme also applies to partial traversals of
343 >     * ranges of bins (via an alternate Traverser constructor)
344 >     * to support partitioned aggregate operations.  Also, read-only
345 >     * operations give up if ever forwarded to a null table, which
346 >     * provides support for shutdown-style clearing, which is also not
347 >     * currently implemented.
348       *
349       * Lazy table initialization minimizes footprint until first use,
350       * and also avoids resizings when the first operation is from a
351       * putAll, constructor with map argument, or deserialization.
352 <     * These cases attempt to override the targetCapacity used in
353 <     * growTable. These harmlessly fail to take effect in cases of
223 <     * races with other ongoing resizings. Uses of the threshold and
224 <     * targetCapacity during attempted initializations or resizings
225 <     * are racy but fall back on checks to preserve correctness.
352 >     * These cases attempt to override the initial capacity settings,
353 >     * but harmlessly fail to take effect in cases of races.
354       *
355       * The element count is maintained using a LongAdder, which avoids
356       * contention on updates but can encounter cache thrashing if read
357       * too frequently during concurrent access. To avoid reading so
358 <     * often, resizing is normally attempted only upon adding to a bin
359 <     * already holding two or more nodes. Under uniform hash
360 <     * distributions, the probability of this occurring at threshold
361 <     * is around 13%, meaning that only about 1 in 8 puts check
362 <     * threshold (and after resizing, many fewer do so). But this
363 <     * approximation has high variance for small table sizes, so we
364 <     * check on any collision for sizes <= 64.  Further, to increase
365 <     * the probability that a resize occurs soon enough, we offset the
366 <     * threshold (see THRESHOLD_OFFSET) by the expected number of puts
367 <     * between checks.
358 >     * often, resizing is attempted either when a bin lock is
359 >     * contended, or upon adding to a bin already holding two or more
360 >     * nodes (checked before adding in the xIfAbsent methods, after
361 >     * adding in others). Under uniform hash distributions, the
362 >     * probability of this occurring at threshold is around 13%,
363 >     * meaning that only about 1 in 8 puts check threshold (and after
364 >     * resizing, many fewer do so). But this approximation has high
365 >     * variance for small table sizes, so we check on any collision
366 >     * for sizes <= 64. The bulk putAll operation further reduces
367 >     * contention by only committing count updates upon these size
368 >     * checks.
369       *
370       * Maintaining API and serialization compatibility with previous
371       * versions of this class introduces several oddities. Mainly: We
372       * leave untouched but unused constructor arguments refering to
373 <     * concurrencyLevel. We also declare an unused "Segment" class
374 <     * that is instantiated in minimal form only when serializing.
373 >     * concurrencyLevel. We accept a loadFactor constructor argument,
374 >     * but apply it only to initial table capacity (which is the only
375 >     * time that we can guarantee to honor it.) We also declare an
376 >     * unused "Segment" class that is instantiated in minimal form
377 >     * only when serializing.
378       */
379  
380      /* ---------------- Constants -------------- */
# Line 250 | Line 382 | public class ConcurrentHashMapV8<K, V>
382      /**
383       * The largest possible table capacity.  This value must be
384       * exactly 1<<30 to stay within Java array allocation and indexing
385 <     * bounds for power of two table sizes.
385 >     * bounds for power of two table sizes, and is further required
386 >     * because the top two bits of 32bit hash fields are used for
387 >     * control purposes.
388       */
389      private static final int MAXIMUM_CAPACITY = 1 << 30;
390  
# Line 261 | Line 395 | public class ConcurrentHashMapV8<K, V>
395      private static final int DEFAULT_CAPACITY = 16;
396  
397      /**
398 <     * The load factor for this table. Overrides of this value in
399 <     * constructors affect only the initial table capacity.  The
266 <     * actual floating point value isn't normally used, because it is
267 <     * simpler to rely on the expression {@code n - (n >>> 2)} for the
268 <     * associated resizing threshold.
398 >     * The largest possible (non-power of two) array size.
399 >     * Needed by toArray and related methods.
400       */
401 <    private static final float LOAD_FACTOR = 0.75f;
401 >    static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
402  
403      /**
404 <     * The count value to offset thresholds to compensate for checking
405 <     * for the need to resize only when inserting into bins with two
275 <     * or more elements. See above for explanation.
404 >     * The default concurrency level for this table. Unused but
405 >     * defined for compatibility with previous versions of this class.
406       */
407 <    private static final int THRESHOLD_OFFSET = 8;
407 >    private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
408  
409      /**
410 <     * The default concurrency level for this table. Unused except as
411 <     * a sizing hint, but defined for compatibility with previous
412 <     * versions of this class.
410 >     * The load factor for this table. Overrides of this value in
411 >     * constructors affect only the initial table capacity.  The
412 >     * actual floating point value isn't normally used -- it is
413 >     * simpler to use expressions such as {@code n - (n >>> 2)} for
414 >     * the associated resizing threshold.
415       */
416 <    private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
285 <
286 <    /* ---------------- Nodes -------------- */
416 >    private static final float LOAD_FACTOR = 0.75f;
417  
418      /**
419 <     * Key-value entry. Note that this is never exported out as a
420 <     * user-visible Map.Entry. Nodes with a negative hash field are
421 <     * special, and do not contain user keys or values.  Otherwise,
292 <     * keys are never null, and null val fields indicate that a node
293 <     * is in the process of being deleted or created. For purposes of
294 <     * read-only, access, a key may be read before a val, but can only
295 <     * be used after checking val.  (For an update operation, when a
296 <     * lock is held on a node, order doesn't matter.)
419 >     * The buffer size for skipped bins during transfers. The
420 >     * value is arbitrary but should be large enough to avoid
421 >     * most locking stalls during resizes.
422       */
423 <    static final class Node {
299 <        final int hash;
300 <        final Object key;
301 <        volatile Object val;
302 <        volatile Node next;
303 <
304 <        Node(int hash, Object key, Object val, Node next) {
305 <            this.hash = hash;
306 <            this.key = key;
307 <            this.val = val;
308 <            this.next = next;
309 <        }
310 <    }
423 >    private static final int TRANSFER_BUFFER_SIZE = 32;
424  
425      /**
426 <     * Sign bit of node hash value indicating to use table in node.key.
426 >     * The bin count threshold for using a tree rather than list for a
427 >     * bin.  The value reflects the approximate break-even point for
428 >     * using tree-based operations.
429 >     */
430 >    private static final int TREE_THRESHOLD = 8;
431 >
432 >    /*
433 >     * Encodings for special uses of Node hash fields. See above for
434 >     * explanation.
435       */
436 <    private static final int SIGN_BIT = 0x80000000;
436 >    static final int MOVED     = 0x80000000; // hash field for forwarding nodes
437 >    static final int LOCKED    = 0x40000000; // set/tested only as a bit
438 >    static final int WAITING   = 0xc0000000; // both bits set/tested together
439 >    static final int HASH_BITS = 0x3fffffff; // usable bits of normal node hash
440  
441      /* ---------------- Fields -------------- */
442  
# Line 322 | Line 446 | public class ConcurrentHashMapV8<K, V>
446       */
447      transient volatile Node[] table;
448  
449 <    /** The counter maintaining number of elements. */
449 >    /**
450 >     * The counter maintaining number of elements.
451 >     */
452      private transient final LongAdder counter;
453 <    /** Nonzero when table is being initialized or resized. Updated via CAS. */
454 <    private transient volatile int resizing;
455 <    /** The next element count value upon which to resize the table. */
456 <    private transient int threshold;
457 <    /** The target capacity; volatile to cover initialization races. */
458 <    private transient volatile int targetCapacity;
453 >
454 >    /**
455 >     * Table initialization and resizing control.  When negative, the
456 >     * table is being initialized or resized. Otherwise, when table is
457 >     * null, holds the initial table size to use upon creation, or 0
458 >     * for default. After initialization, holds the next element count
459 >     * value upon which to resize the table.
460 >     */
461 >    private transient volatile int sizeCtl;
462  
463      // views
464      private transient KeySet<K,V> keySet;
# Line 353 | Line 482 | public class ConcurrentHashMapV8<K, V>
482       * inline assignments below.
483       */
484  
485 <    static final Node tabAt(Node[] tab, int i) { // used by InternalIterator
485 >    static final Node tabAt(Node[] tab, int i) { // used by Iter
486          return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE);
487      }
488  
# Line 365 | Line 494 | public class ConcurrentHashMapV8<K, V>
494          UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v);
495      }
496  
497 <    /* ----------------Table Initialization and Resizing -------------- */
497 >    /* ---------------- Nodes -------------- */
498  
499      /**
500 <     * Returns a power of two table size for the given desired capacity.
501 <     * See Hackers Delight, sec 3.2
500 >     * Key-value entry. Note that this is never exported out as a
501 >     * user-visible Map.Entry (see MapEntry below). Nodes with a hash
502 >     * field of MOVED are special, and do not contain user keys or
503 >     * values.  Otherwise, keys are never null, and null val fields
504 >     * indicate that a node is in the process of being deleted or
505 >     * created. For purposes of read-only access, a key may be read
506 >     * before a val, but can only be used after checking val to be
507 >     * non-null.
508       */
509 <    private static final int tableSizeFor(int c) {
510 <        int n = c - 1;
511 <        n |= n >>> 1;
512 <        n |= n >>> 2;
513 <        n |= n >>> 4;
379 <        n |= n >>> 8;
380 <        n |= n >>> 16;
381 <        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
382 <    }
509 >    static class Node {
510 >        volatile int hash;
511 >        final Object key;
512 >        volatile Object val;
513 >        volatile Node next;
514  
515 <    /**
516 <     * If not already resizing, initializes or creates next table and
517 <     * transfers bins. Initial table size uses the capacity recorded
518 <     * in targetCapacity.  Rechecks occupancy after a transfer to see
519 <     * if another resize is already needed because resizings are
520 <     * lagging additions.
521 <     *
522 <     * @return current table
523 <     */
524 <    private final Node[] growTable() {
525 <        if (resizing == 0 &&
526 <            UNSAFE.compareAndSwapInt(this, resizingOffset, 0, 1)) {
527 <            try {
528 <                for (;;) {
529 <                    Node[] tab = table;
530 <                    int n, c, m;
531 <                    if (tab == null)
532 <                        n = (c = targetCapacity) > 0 ? c : DEFAULT_CAPACITY;
533 <                    else if ((m = tab.length) < MAXIMUM_CAPACITY &&
534 <                             counter.sum() >= (long)threshold)
535 <                        n = m << 1;
536 <                    else
537 <                        break;
538 <                    threshold = n - (n >>> 2) - THRESHOLD_OFFSET;
539 <                    Node[] nextTab = new Node[n];
540 <                    if (tab != null)
541 <                        transfer(tab, nextTab,
542 <                                 new Node(SIGN_BIT, nextTab, null, null));
543 <                    table = nextTab;
544 <                    if (tab == null)
515 >        Node(int hash, Object key, Object val, Node next) {
516 >            this.hash = hash;
517 >            this.key = key;
518 >            this.val = val;
519 >            this.next = next;
520 >        }
521 >
522 >        /** CompareAndSet the hash field */
523 >        final boolean casHash(int cmp, int val) {
524 >            return UNSAFE.compareAndSwapInt(this, hashOffset, cmp, val);
525 >        }
526 >
527 >        /** The number of spins before blocking for a lock */
528 >        static final int MAX_SPINS =
529 >            Runtime.getRuntime().availableProcessors() > 1 ? 64 : 1;
530 >
531 >        /**
532 >         * Spins a while if LOCKED bit set and this node is the first
533 >         * of its bin, and then sets WAITING bits on hash field and
534 >         * blocks (once) if they are still set.  It is OK for this
535 >         * method to return even if lock is not available upon exit,
536 >         * which enables these simple single-wait mechanics.
537 >         *
538 >         * The corresponding signalling operation is performed within
539 >         * callers: Upon detecting that WAITING has been set when
540 >         * unlocking lock (via a failed CAS from non-waiting LOCKED
541 >         * state), unlockers acquire the sync lock and perform a
542 >         * notifyAll.
543 >         *
544 >         * The initial sanity check on tab and bounds is not currently
545 >         * necessary in the only usages of this method, but enables
546 >         * use in other future contexts.
547 >         */
548 >        final void tryAwaitLock(Node[] tab, int i) {
549 >            if (tab != null && i >= 0 && i < tab.length) { // sanity check
550 >                int r = ThreadLocalRandom.current().nextInt(); // randomize spins
551 >                int spins = MAX_SPINS, h;
552 >                while (tabAt(tab, i) == this && ((h = hash) & LOCKED) != 0) {
553 >                    if (spins >= 0) {
554 >                        r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
555 >                        if (r >= 0 && --spins == 0)
556 >                            Thread.yield();  // yield before block
557 >                    }
558 >                    else if (casHash(h, h | WAITING)) {
559 >                        synchronized (this) {
560 >                            if (tabAt(tab, i) == this &&
561 >                                (hash & WAITING) == WAITING) {
562 >                                try {
563 >                                    wait();
564 >                                } catch (InterruptedException ie) {
565 >                                    Thread.currentThread().interrupt();
566 >                                }
567 >                            }
568 >                            else
569 >                                notifyAll(); // possibly won race vs signaller
570 >                        }
571                          break;
572 +                    }
573                  }
416            } finally {
417                resizing = 0;
574              }
575          }
576 <        else if (table == null)
577 <            Thread.yield(); // lost initialization race; just spin
578 <        return table;
576 >
577 >        // Unsafe mechanics for casHash
578 >        private static final sun.misc.Unsafe UNSAFE;
579 >        private static final long hashOffset;
580 >
581 >        static {
582 >            try {
583 >                UNSAFE = getUnsafe();
584 >                Class<?> k = Node.class;
585 >                hashOffset = UNSAFE.objectFieldOffset
586 >                    (k.getDeclaredField("hash"));
587 >            } catch (Exception e) {
588 >                throw new Error(e);
589 >            }
590 >        }
591      }
592  
593 <    /*
594 <     * Reclassifies nodes in each bin to new table.  Because we are
595 <     * using power-of-two expansion, the elements from each bin must
596 <     * either stay at same index, or move with a power of two
429 <     * offset. We eliminate unnecessary node creation by catching
430 <     * cases where old nodes can be reused because their next fields
431 <     * won't change.  Statistically, only about one-sixth of them need
432 <     * cloning when a table doubles. The nodes they replace will be
433 <     * garbage collectable as soon as they are no longer referenced by
434 <     * any reader thread that may be in the midst of concurrently
435 <     * traversing table.
436 <     *
437 <     * Transfers are done from the bottom up to preserve iterator
438 <     * traversability. On each step, the old bin is locked,
439 <     * moved/copied, and then replaced with a forwarding node.
593 >    /* ---------------- TreeBins -------------- */
594 >
595 >    /**
596 >     * Nodes for use in TreeBins
597       */
598 <    private static final void transfer(Node[] tab, Node[] nextTab, Node fwd) {
599 <        int n = tab.length;
600 <        Node ignore = nextTab[n + n - 1]; // force bounds check
601 <        for (int i = n - 1; i >= 0; --i) {
602 <            for (Node e;;) {
603 <                if ((e = tabAt(tab, i)) != null) {
604 <                    boolean validated = false;
605 <                    synchronized (e) {
606 <                        if (tabAt(tab, i) == e) {
607 <                            validated = true;
608 <                            Node lo = null, hi = null, lastRun = e;
609 <                            int runBit = e.hash & n;
610 <                            for (Node p = e.next; p != null; p = p.next) {
611 <                                int b = p.hash & n;
612 <                                if (b != runBit) {
613 <                                    runBit = b;
614 <                                    lastRun = p;
598 >    static final class TreeNode extends Node {
599 >        TreeNode parent;  // red-black tree links
600 >        TreeNode left;
601 >        TreeNode right;
602 >        TreeNode prev;    // needed to unlink next upon deletion
603 >        boolean red;
604 >
605 >        TreeNode(int hash, Object key, Object val, Node next, TreeNode parent) {
606 >            super(hash, key, val, next);
607 >            this.parent = parent;
608 >        }
609 >    }
610 >
611 >    /**
612 >     * A specialized form of red-black tree for use in bins
613 >     * whose size exceeds a threshold.
614 >     *
615 >     * TreeBins use a special form of comparison for search and
616 >     * related operations (which is the main reason we cannot use
617 >     * existing collections such as TreeMaps). TreeBins contain
618 >     * Comparable elements, but may contain others, as well as
619 >     * elements that are Comparable but not necessarily Comparable<T>
620 >     * for the same T, so we cannot invoke compareTo among them. To
621 >     * handle this, the tree is ordered primarily by hash value, then
622 >     * by getClass().getName() order, and then by Comparator order
623 >     * among elements of the same class.  On lookup at a node, if
624 >     * elements are not comparable or compare as 0, both left and
625 >     * right children may need to be searched in the case of tied hash
626 >     * values. (This corresponds to the full list search that would be
627 >     * necessary if all elements were non-Comparable and had tied
628 >     * hashes.)  The red-black balancing code is updated from
629 >     * pre-jdk-collections
630 >     * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
631 >     * based in turn on Cormen, Leiserson, and Rivest "Introduction to
632 >     * Algorithms" (CLR).
633 >     *
634 >     * TreeBins also maintain a separate locking discipline than
635 >     * regular bins. Because they are forwarded via special MOVED
636 >     * nodes at bin heads (which can never change once established),
637 >     * we cannot use those nodes as locks. Instead, TreeBin
638 >     * extends AbstractQueuedSynchronizer to support a simple form of
639 >     * read-write lock. For update operations and table validation,
640 >     * the exclusive form of lock behaves in the same way as bin-head
641 >     * locks. However, lookups use shared read-lock mechanics to allow
642 >     * multiple readers in the absence of writers.  Additionally,
643 >     * these lookups do not ever block: While the lock is not
644 >     * available, they proceed along the slow traversal path (via
645 >     * next-pointers) until the lock becomes available or the list is
646 >     * exhausted, whichever comes first. (These cases are not fast,
647 >     * but maximize aggregate expected throughput.)  The AQS mechanics
648 >     * for doing this are straightforward.  The lock state is held as
649 >     * AQS getState().  Read counts are negative; the write count (1)
650 >     * is positive.  There are no signalling preferences among readers
651 >     * and writers. Since we don't need to export full Lock API, we
652 >     * just override the minimal AQS methods and use them directly.
653 >     */
654 >    static final class TreeBin extends AbstractQueuedSynchronizer {
655 >        private static final long serialVersionUID = 2249069246763182397L;
656 >        transient TreeNode root;  // root of tree
657 >        transient TreeNode first; // head of next-pointer list
658 >
659 >        /* AQS overrides */
660 >        public final boolean isHeldExclusively() { return getState() > 0; }
661 >        public final boolean tryAcquire(int ignore) {
662 >            if (compareAndSetState(0, 1)) {
663 >                setExclusiveOwnerThread(Thread.currentThread());
664 >                return true;
665 >            }
666 >            return false;
667 >        }
668 >        public final boolean tryRelease(int ignore) {
669 >            setExclusiveOwnerThread(null);
670 >            setState(0);
671 >            return true;
672 >        }
673 >        public final int tryAcquireShared(int ignore) {
674 >            for (int c;;) {
675 >                if ((c = getState()) > 0)
676 >                    return -1;
677 >                if (compareAndSetState(c, c -1))
678 >                    return 1;
679 >            }
680 >        }
681 >        public final boolean tryReleaseShared(int ignore) {
682 >            int c;
683 >            do {} while (!compareAndSetState(c = getState(), c + 1));
684 >            return c == -1;
685 >        }
686 >
687 >        /** From CLR */
688 >        private void rotateLeft(TreeNode p) {
689 >            if (p != null) {
690 >                TreeNode r = p.right, pp, rl;
691 >                if ((rl = p.right = r.left) != null)
692 >                    rl.parent = p;
693 >                if ((pp = r.parent = p.parent) == null)
694 >                    root = r;
695 >                else if (pp.left == p)
696 >                    pp.left = r;
697 >                else
698 >                    pp.right = r;
699 >                r.left = p;
700 >                p.parent = r;
701 >            }
702 >        }
703 >
704 >        /** From CLR */
705 >        private void rotateRight(TreeNode p) {
706 >            if (p != null) {
707 >                TreeNode l = p.left, pp, lr;
708 >                if ((lr = p.left = l.right) != null)
709 >                    lr.parent = p;
710 >                if ((pp = l.parent = p.parent) == null)
711 >                    root = l;
712 >                else if (pp.right == p)
713 >                    pp.right = l;
714 >                else
715 >                    pp.left = l;
716 >                l.right = p;
717 >                p.parent = l;
718 >            }
719 >        }
720 >
721 >        /**
722 >         * Returns the TreeNode (or null if not found) for the given key
723 >         * starting at given root.
724 >         */
725 >        @SuppressWarnings("unchecked") final TreeNode getTreeNode
726 >            (int h, Object k, TreeNode p) {
727 >            Class<?> c = k.getClass();
728 >            while (p != null) {
729 >                int dir, ph;  Object pk; Class<?> pc;
730 >                if ((ph = p.hash) == h) {
731 >                    if ((pk = p.key) == k || k.equals(pk))
732 >                        return p;
733 >                    if (c != (pc = pk.getClass()) ||
734 >                        !(k instanceof Comparable) ||
735 >                        (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
736 >                        dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName());
737 >                        TreeNode r = null, s = null, pl, pr;
738 >                        if (dir >= 0) {
739 >                            if ((pl = p.left) != null && h <= pl.hash)
740 >                                s = pl;
741 >                        }
742 >                        else if ((pr = p.right) != null && h >= pr.hash)
743 >                            s = pr;
744 >                        if (s != null && (r = getTreeNode(h, k, s)) != null)
745 >                            return r;
746 >                    }
747 >                }
748 >                else
749 >                    dir = (h < ph) ? -1 : 1;
750 >                p = (dir > 0) ? p.right : p.left;
751 >            }
752 >            return null;
753 >        }
754 >
755 >        /**
756 >         * Wrapper for getTreeNode used by CHM.get. Tries to obtain
757 >         * read-lock to call getTreeNode, but during failure to get
758 >         * lock, searches along next links.
759 >         */
760 >        final Object getValue(int h, Object k) {
761 >            Node r = null;
762 >            int c = getState(); // Must read lock state first
763 >            for (Node e = first; e != null; e = e.next) {
764 >                if (c <= 0 && compareAndSetState(c, c - 1)) {
765 >                    try {
766 >                        r = getTreeNode(h, k, root);
767 >                    } finally {
768 >                        releaseShared(0);
769 >                    }
770 >                    break;
771 >                }
772 >                else if ((e.hash & HASH_BITS) == h && k.equals(e.key)) {
773 >                    r = e;
774 >                    break;
775 >                }
776 >                else
777 >                    c = getState();
778 >            }
779 >            return r == null ? null : r.val;
780 >        }
781 >
782 >        /**
783 >         * Finds or adds a node.
784 >         * @return null if added
785 >         */
786 >        @SuppressWarnings("unchecked") final TreeNode putTreeNode
787 >            (int h, Object k, Object v) {
788 >            Class<?> c = k.getClass();
789 >            TreeNode pp = root, p = null;
790 >            int dir = 0;
791 >            while (pp != null) { // find existing node or leaf to insert at
792 >                int ph;  Object pk; Class<?> pc;
793 >                p = pp;
794 >                if ((ph = p.hash) == h) {
795 >                    if ((pk = p.key) == k || k.equals(pk))
796 >                        return p;
797 >                    if (c != (pc = pk.getClass()) ||
798 >                        !(k instanceof Comparable) ||
799 >                        (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
800 >                        dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName());
801 >                        TreeNode r = null, s = null, pl, pr;
802 >                        if (dir >= 0) {
803 >                            if ((pl = p.left) != null && h <= pl.hash)
804 >                                s = pl;
805 >                        }
806 >                        else if ((pr = p.right) != null && h >= pr.hash)
807 >                            s = pr;
808 >                        if (s != null && (r = getTreeNode(h, k, s)) != null)
809 >                            return r;
810 >                    }
811 >                }
812 >                else
813 >                    dir = (h < ph) ? -1 : 1;
814 >                pp = (dir > 0) ? p.right : p.left;
815 >            }
816 >
817 >            TreeNode f = first;
818 >            TreeNode x = first = new TreeNode(h, k, v, f, p);
819 >            if (p == null)
820 >                root = x;
821 >            else { // attach and rebalance; adapted from CLR
822 >                TreeNode xp, xpp;
823 >                if (f != null)
824 >                    f.prev = x;
825 >                if (dir <= 0)
826 >                    p.left = x;
827 >                else
828 >                    p.right = x;
829 >                x.red = true;
830 >                while (x != null && (xp = x.parent) != null && xp.red &&
831 >                       (xpp = xp.parent) != null) {
832 >                    TreeNode xppl = xpp.left;
833 >                    if (xp == xppl) {
834 >                        TreeNode y = xpp.right;
835 >                        if (y != null && y.red) {
836 >                            y.red = false;
837 >                            xp.red = false;
838 >                            xpp.red = true;
839 >                            x = xpp;
840 >                        }
841 >                        else {
842 >                            if (x == xp.right) {
843 >                                rotateLeft(x = xp);
844 >                                xpp = (xp = x.parent) == null ? null : xp.parent;
845 >                            }
846 >                            if (xp != null) {
847 >                                xp.red = false;
848 >                                if (xpp != null) {
849 >                                    xpp.red = true;
850 >                                    rotateRight(xpp);
851                                  }
852                              }
853 <                            if (runBit == 0)
854 <                                lo = lastRun;
855 <                            else
856 <                                hi = lastRun;
857 <                            for (Node p = e; p != lastRun; p = p.next) {
858 <                                int ph = p.hash;
859 <                                Object pk = p.key, pv = p.val;
860 <                                if ((ph & n) == 0)
861 <                                    lo = new Node(ph, pk, pv, lo);
862 <                                else
863 <                                    hi = new Node(ph, pk, pv, hi);
853 >                        }
854 >                    }
855 >                    else {
856 >                        TreeNode y = xppl;
857 >                        if (y != null && y.red) {
858 >                            y.red = false;
859 >                            xp.red = false;
860 >                            xpp.red = true;
861 >                            x = xpp;
862 >                        }
863 >                        else {
864 >                            if (x == xp.left) {
865 >                                rotateRight(x = xp);
866 >                                xpp = (xp = x.parent) == null ? null : xp.parent;
867 >                            }
868 >                            if (xp != null) {
869 >                                xp.red = false;
870 >                                if (xpp != null) {
871 >                                    xpp.red = true;
872 >                                    rotateLeft(xpp);
873 >                                }
874                              }
472                            setTabAt(nextTab, i, lo);
473                            setTabAt(nextTab, i + n, hi);
474                            setTabAt(tab, i, fwd);
875                          }
876                      }
877 <                    if (validated)
877 >                }
878 >                TreeNode r = root;
879 >                if (r != null && r.red)
880 >                    r.red = false;
881 >            }
882 >            return null;
883 >        }
884 >
885 >        /**
886 >         * Removes the given node, that must be present before this
887 >         * call.  This is messier than typical red-black deletion code
888 >         * because we cannot swap the contents of an interior node
889 >         * with a leaf successor that is pinned by "next" pointers
890 >         * that are accessible independently of lock. So instead we
891 >         * swap the tree linkages.
892 >         */
893 >        final void deleteTreeNode(TreeNode p) {
894 >            TreeNode next = (TreeNode)p.next; // unlink traversal pointers
895 >            TreeNode pred = p.prev;
896 >            if (pred == null)
897 >                first = next;
898 >            else
899 >                pred.next = next;
900 >            if (next != null)
901 >                next.prev = pred;
902 >            TreeNode replacement;
903 >            TreeNode pl = p.left;
904 >            TreeNode pr = p.right;
905 >            if (pl != null && pr != null) {
906 >                TreeNode s = pr, sl;
907 >                while ((sl = s.left) != null) // find successor
908 >                    s = sl;
909 >                boolean c = s.red; s.red = p.red; p.red = c; // swap colors
910 >                TreeNode sr = s.right;
911 >                TreeNode pp = p.parent;
912 >                if (s == pr) { // p was s's direct parent
913 >                    p.parent = s;
914 >                    s.right = p;
915 >                }
916 >                else {
917 >                    TreeNode sp = s.parent;
918 >                    if ((p.parent = sp) != null) {
919 >                        if (s == sp.left)
920 >                            sp.left = p;
921 >                        else
922 >                            sp.right = p;
923 >                    }
924 >                    if ((s.right = pr) != null)
925 >                        pr.parent = s;
926 >                }
927 >                p.left = null;
928 >                if ((p.right = sr) != null)
929 >                    sr.parent = p;
930 >                if ((s.left = pl) != null)
931 >                    pl.parent = s;
932 >                if ((s.parent = pp) == null)
933 >                    root = s;
934 >                else if (p == pp.left)
935 >                    pp.left = s;
936 >                else
937 >                    pp.right = s;
938 >                replacement = sr;
939 >            }
940 >            else
941 >                replacement = (pl != null) ? pl : pr;
942 >            TreeNode pp = p.parent;
943 >            if (replacement == null) {
944 >                if (pp == null) {
945 >                    root = null;
946 >                    return;
947 >                }
948 >                replacement = p;
949 >            }
950 >            else {
951 >                replacement.parent = pp;
952 >                if (pp == null)
953 >                    root = replacement;
954 >                else if (p == pp.left)
955 >                    pp.left = replacement;
956 >                else
957 >                    pp.right = replacement;
958 >                p.left = p.right = p.parent = null;
959 >            }
960 >            if (!p.red) { // rebalance, from CLR
961 >                TreeNode x = replacement;
962 >                while (x != null) {
963 >                    TreeNode xp, xpl;
964 >                    if (x.red || (xp = x.parent) == null) {
965 >                        x.red = false;
966                          break;
967 +                    }
968 +                    if (x == (xpl = xp.left)) {
969 +                        TreeNode sib = xp.right;
970 +                        if (sib != null && sib.red) {
971 +                            sib.red = false;
972 +                            xp.red = true;
973 +                            rotateLeft(xp);
974 +                            sib = (xp = x.parent) == null ? null : xp.right;
975 +                        }
976 +                        if (sib == null)
977 +                            x = xp;
978 +                        else {
979 +                            TreeNode sl = sib.left, sr = sib.right;
980 +                            if ((sr == null || !sr.red) &&
981 +                                (sl == null || !sl.red)) {
982 +                                sib.red = true;
983 +                                x = xp;
984 +                            }
985 +                            else {
986 +                                if (sr == null || !sr.red) {
987 +                                    if (sl != null)
988 +                                        sl.red = false;
989 +                                    sib.red = true;
990 +                                    rotateRight(sib);
991 +                                    sib = (xp = x.parent) == null ? null : xp.right;
992 +                                }
993 +                                if (sib != null) {
994 +                                    sib.red = (xp == null) ? false : xp.red;
995 +                                    if ((sr = sib.right) != null)
996 +                                        sr.red = false;
997 +                                }
998 +                                if (xp != null) {
999 +                                    xp.red = false;
1000 +                                    rotateLeft(xp);
1001 +                                }
1002 +                                x = root;
1003 +                            }
1004 +                        }
1005 +                    }
1006 +                    else { // symmetric
1007 +                        TreeNode sib = xpl;
1008 +                        if (sib != null && sib.red) {
1009 +                            sib.red = false;
1010 +                            xp.red = true;
1011 +                            rotateRight(xp);
1012 +                            sib = (xp = x.parent) == null ? null : xp.left;
1013 +                        }
1014 +                        if (sib == null)
1015 +                            x = xp;
1016 +                        else {
1017 +                            TreeNode sl = sib.left, sr = sib.right;
1018 +                            if ((sl == null || !sl.red) &&
1019 +                                (sr == null || !sr.red)) {
1020 +                                sib.red = true;
1021 +                                x = xp;
1022 +                            }
1023 +                            else {
1024 +                                if (sl == null || !sl.red) {
1025 +                                    if (sr != null)
1026 +                                        sr.red = false;
1027 +                                    sib.red = true;
1028 +                                    rotateLeft(sib);
1029 +                                    sib = (xp = x.parent) == null ? null : xp.left;
1030 +                                }
1031 +                                if (sib != null) {
1032 +                                    sib.red = (xp == null) ? false : xp.red;
1033 +                                    if ((sl = sib.left) != null)
1034 +                                        sl.red = false;
1035 +                                }
1036 +                                if (xp != null) {
1037 +                                    xp.red = false;
1038 +                                    rotateRight(xp);
1039 +                                }
1040 +                                x = root;
1041 +                            }
1042 +                        }
1043 +                    }
1044                  }
1045 <                else if (casTabAt(tab, i, e, fwd))
1046 <                    break;
1045 >            }
1046 >            if (p == replacement && (pp = p.parent) != null) {
1047 >                if (p == pp.left) // detach pointers
1048 >                    pp.left = null;
1049 >                else if (p == pp.right)
1050 >                    pp.right = null;
1051 >                p.parent = null;
1052              }
1053          }
1054      }
1055  
1056 <    /* ---------------- Internal access and update methods -------------- */
1056 >    /* ---------------- Collision reduction methods -------------- */
1057  
1058      /**
1059 <     * Applies a supplemental hash function to a given hashCode, which
1060 <     * defends against poor quality hash functions.  The result must
1061 <     * be non-negative, and for reasonable performance must have good
1062 <     * avalanche properties; i.e., that each bit of the argument
1063 <     * affects each bit (except sign bit) of the result.
1059 >     * Spreads higher bits to lower, and also forces top 2 bits to 0.
1060 >     * Because the table uses power-of-two masking, sets of hashes
1061 >     * that vary only in bits above the current mask will always
1062 >     * collide. (Among known examples are sets of Float keys holding
1063 >     * consecutive whole numbers in small tables.)  To counter this,
1064 >     * we apply a transform that spreads the impact of higher bits
1065 >     * downward. There is a tradeoff between speed, utility, and
1066 >     * quality of bit-spreading. Because many common sets of hashes
1067 >     * are already reasonably distributed across bits (so don't benefit
1068 >     * from spreading), and because we use trees to handle large sets
1069 >     * of collisions in bins, we don't need excessively high quality.
1070       */
1071      private static final int spread(int h) {
1072 <        // Apply base step of MurmurHash; see http://code.google.com/p/smhasher/
1073 <        h ^= h >>> 16;
1074 <        h *= 0x85ebca6b;
1075 <        h ^= h >>> 13;
1076 <        h *= 0xc2b2ae35;
1077 <        return (h >>> 16) ^ (h & 0x7fffffff); // mask out sign bit
1072 >        h ^= (h >>> 18) ^ (h >>> 12);
1073 >        return (h ^ (h >>> 10)) & HASH_BITS;
1074 >    }
1075 >
1076 >    /**
1077 >     * Replaces a list bin with a tree bin. Call only when locked.
1078 >     * Fails to replace if the given key is non-comparable or table
1079 >     * is, or needs, resizing.
1080 >     */
1081 >    private final void replaceWithTreeBin(Node[] tab, int index, Object key) {
1082 >        if ((key instanceof Comparable) &&
1083 >            (tab.length >= MAXIMUM_CAPACITY || counter.sum() < (long)sizeCtl)) {
1084 >            TreeBin t = new TreeBin();
1085 >            for (Node e = tabAt(tab, index); e != null; e = e.next)
1086 >                t.putTreeNode(e.hash & HASH_BITS, e.key, e.val);
1087 >            setTabAt(tab, index, new Node(MOVED, t, null, null));
1088 >        }
1089      }
1090  
1091 +    /* ---------------- Internal access and update methods -------------- */
1092 +
1093      /** Implementation for get and containsKey */
1094      private final Object internalGet(Object k) {
1095          int h = spread(k.hashCode());
1096          retry: for (Node[] tab = table; tab != null;) {
1097 <            Node e; Object ek, ev; int eh;  // locals to read fields once
1097 >            Node e, p; Object ek, ev; int eh;      // locals to read fields once
1098              for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) {
1099 <                if ((eh = e.hash) == h) {
1100 <                    if ((ev = e.val) != null &&
1101 <                        ((ek = e.key) == k || k.equals(ek)))
1102 <                        return ev;
1103 <                }
1104 <                else if (eh < 0) {          // sign bit set
1105 <                    tab = (Node[])e.key;    // bin was moved during resize
517 <                    continue retry;
1099 >                if ((eh = e.hash) == MOVED) {
1100 >                    if ((ek = e.key) instanceof TreeBin)  // search TreeBin
1101 >                        return ((TreeBin)ek).getValue(h, k);
1102 >                    else {                        // restart with new table
1103 >                        tab = (Node[])ek;
1104 >                        continue retry;
1105 >                    }
1106                  }
1107 +                else if ((eh & HASH_BITS) == h && (ev = e.val) != null &&
1108 +                         ((ek = e.key) == k || k.equals(ek)))
1109 +                    return ev;
1110              }
1111              break;
1112          }
1113          return null;
1114      }
1115  
1116 <    /** Implementation for put and putIfAbsent */
1117 <    private final Object internalPut(Object k, Object v, boolean replace) {
1116 >    /**
1117 >     * Implementation for the four public remove/replace methods:
1118 >     * Replaces node value with v, conditional upon match of cv if
1119 >     * non-null.  If resulting value is null, delete.
1120 >     */
1121 >    private final Object internalReplace(Object k, Object v, Object cv) {
1122 >        int h = spread(k.hashCode());
1123 >        Object oldVal = null;
1124 >        for (Node[] tab = table;;) {
1125 >            Node f; int i, fh; Object fk;
1126 >            if (tab == null ||
1127 >                (f = tabAt(tab, i = (tab.length - 1) & h)) == null)
1128 >                break;
1129 >            else if ((fh = f.hash) == MOVED) {
1130 >                if ((fk = f.key) instanceof TreeBin) {
1131 >                    TreeBin t = (TreeBin)fk;
1132 >                    boolean validated = false;
1133 >                    boolean deleted = false;
1134 >                    t.acquire(0);
1135 >                    try {
1136 >                        if (tabAt(tab, i) == f) {
1137 >                            validated = true;
1138 >                            TreeNode p = t.getTreeNode(h, k, t.root);
1139 >                            if (p != null) {
1140 >                                Object pv = p.val;
1141 >                                if (cv == null || cv == pv || cv.equals(pv)) {
1142 >                                    oldVal = pv;
1143 >                                    if ((p.val = v) == null) {
1144 >                                        deleted = true;
1145 >                                        t.deleteTreeNode(p);
1146 >                                    }
1147 >                                }
1148 >                            }
1149 >                        }
1150 >                    } finally {
1151 >                        t.release(0);
1152 >                    }
1153 >                    if (validated) {
1154 >                        if (deleted)
1155 >                            counter.add(-1L);
1156 >                        break;
1157 >                    }
1158 >                }
1159 >                else
1160 >                    tab = (Node[])fk;
1161 >            }
1162 >            else if ((fh & HASH_BITS) != h && f.next == null) // precheck
1163 >                break;                          // rules out possible existence
1164 >            else if ((fh & LOCKED) != 0) {
1165 >                checkForResize();               // try resizing if can't get lock
1166 >                f.tryAwaitLock(tab, i);
1167 >            }
1168 >            else if (f.casHash(fh, fh | LOCKED)) {
1169 >                boolean validated = false;
1170 >                boolean deleted = false;
1171 >                try {
1172 >                    if (tabAt(tab, i) == f) {
1173 >                        validated = true;
1174 >                        for (Node e = f, pred = null;;) {
1175 >                            Object ek, ev;
1176 >                            if ((e.hash & HASH_BITS) == h &&
1177 >                                ((ev = e.val) != null) &&
1178 >                                ((ek = e.key) == k || k.equals(ek))) {
1179 >                                if (cv == null || cv == ev || cv.equals(ev)) {
1180 >                                    oldVal = ev;
1181 >                                    if ((e.val = v) == null) {
1182 >                                        deleted = true;
1183 >                                        Node en = e.next;
1184 >                                        if (pred != null)
1185 >                                            pred.next = en;
1186 >                                        else
1187 >                                            setTabAt(tab, i, en);
1188 >                                    }
1189 >                                }
1190 >                                break;
1191 >                            }
1192 >                            pred = e;
1193 >                            if ((e = e.next) == null)
1194 >                                break;
1195 >                        }
1196 >                    }
1197 >                } finally {
1198 >                    if (!f.casHash(fh | LOCKED, fh)) {
1199 >                        f.hash = fh;
1200 >                        synchronized (f) { f.notifyAll(); };
1201 >                    }
1202 >                }
1203 >                if (validated) {
1204 >                    if (deleted)
1205 >                        counter.add(-1L);
1206 >                    break;
1207 >                }
1208 >            }
1209 >        }
1210 >        return oldVal;
1211 >    }
1212 >
1213 >    /*
1214 >     * Internal versions of the six insertion methods, each a
1215 >     * little more complicated than the last. All have
1216 >     * the same basic structure as the first (internalPut):
1217 >     *  1. If table uninitialized, create
1218 >     *  2. If bin empty, try to CAS new node
1219 >     *  3. If bin stale, use new table
1220 >     *  4. if bin converted to TreeBin, validate and relay to TreeBin methods
1221 >     *  5. Lock and validate; if valid, scan and add or update
1222 >     *
1223 >     * The others interweave other checks and/or alternative actions:
1224 >     *  * Plain put checks for and performs resize after insertion.
1225 >     *  * putIfAbsent prescans for mapping without lock (and fails to add
1226 >     *    if present), which also makes pre-emptive resize checks worthwhile.
1227 >     *  * computeIfAbsent extends form used in putIfAbsent with additional
1228 >     *    mechanics to deal with, calls, potential exceptions and null
1229 >     *    returns from function call.
1230 >     *  * compute uses the same function-call mechanics, but without
1231 >     *    the prescans
1232 >     *  * merge acts as putIfAbsent in the absent case, but invokes the
1233 >     *    update function if present
1234 >     *  * putAll attempts to pre-allocate enough table space
1235 >     *    and more lazily performs count updates and checks.
1236 >     *
1237 >     * Someday when details settle down a bit more, it might be worth
1238 >     * some factoring to reduce sprawl.
1239 >     */
1240 >
1241 >    /** Implementation for put */
1242 >    private final Object internalPut(Object k, Object v) {
1243          int h = spread(k.hashCode());
1244 <        Object oldVal = null;               // previous value or null if none
1244 >        int count = 0;
1245          for (Node[] tab = table;;) {
1246 <            Node e; int i; Object ek, ev;
1246 >            int i; Node f; int fh; Object fk;
1247              if (tab == null)
1248 <                tab = growTable();
1249 <            else if ((e = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1248 >                tab = initTable();
1249 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1250                  if (casTabAt(tab, i, null, new Node(h, k, v, null)))
1251                      break;                   // no lock when adding to empty bin
1252              }
1253 <            else if (e.hash < 0)             // resized -- restart with new table
1254 <                tab = (Node[])e.key;
1255 <            else if (!replace && e.hash == h && (ev = e.val) != null &&
1256 <                     ((ek = e.key) == k || k.equals(ek))) {
1257 <                if (tabAt(tab, i) == e) {    // inspect and validate 1st node
1258 <                    oldVal = ev;             // without lock for putIfAbsent
1259 <                    break;
1253 >            else if ((fh = f.hash) == MOVED) {
1254 >                if ((fk = f.key) instanceof TreeBin) {
1255 >                    TreeBin t = (TreeBin)fk;
1256 >                    Object oldVal = null;
1257 >                    t.acquire(0);
1258 >                    try {
1259 >                        if (tabAt(tab, i) == f) {
1260 >                            count = 2;
1261 >                            TreeNode p = t.putTreeNode(h, k, v);
1262 >                            if (p != null) {
1263 >                                oldVal = p.val;
1264 >                                p.val = v;
1265 >                            }
1266 >                        }
1267 >                    } finally {
1268 >                        t.release(0);
1269 >                    }
1270 >                    if (count != 0) {
1271 >                        if (oldVal != null)
1272 >                            return oldVal;
1273 >                        break;
1274 >                    }
1275                  }
1276 +                else
1277 +                    tab = (Node[])fk;
1278              }
1279 <            else {
1280 <                boolean validated = false;
1281 <                boolean checkSize = false;
1282 <                synchronized (e) {           // lock the 1st node of bin list
1283 <                    if (tabAt(tab, i) == e) {
1284 <                        validated = true;    // retry if 1st already deleted
1285 <                        for (Node first = e;;) {
1286 <                            if (e.hash == h &&
1287 <                                ((ek = e.key) == k || k.equals(ek)) &&
1288 <                                (ev = e.val) != null) {
1279 >            else if ((fh & LOCKED) != 0) {
1280 >                checkForResize();
1281 >                f.tryAwaitLock(tab, i);
1282 >            }
1283 >            else if (f.casHash(fh, fh | LOCKED)) {
1284 >                Object oldVal = null;
1285 >                try {                        // needed in case equals() throws
1286 >                    if (tabAt(tab, i) == f) {
1287 >                        count = 1;
1288 >                        for (Node e = f;; ++count) {
1289 >                            Object ek, ev;
1290 >                            if ((e.hash & HASH_BITS) == h &&
1291 >                                (ev = e.val) != null &&
1292 >                                ((ek = e.key) == k || k.equals(ek))) {
1293                                  oldVal = ev;
1294 <                                if (replace)
558 <                                    e.val = v;
1294 >                                e.val = v;
1295                                  break;
1296                              }
1297                              Node last = e;
1298                              if ((e = e.next) == null) {
1299                                  last.next = new Node(h, k, v, null);
1300 <                                if (last != first || tab.length <= 64)
1301 <                                    checkSize = true;
1300 >                                if (count >= TREE_THRESHOLD)
1301 >                                    replaceWithTreeBin(tab, i, k);
1302                                  break;
1303                              }
1304                          }
1305                      }
1306 +                } finally {                  // unlock and signal if needed
1307 +                    if (!f.casHash(fh | LOCKED, fh)) {
1308 +                        f.hash = fh;
1309 +                        synchronized (f) { f.notifyAll(); };
1310 +                    }
1311                  }
1312 <                if (validated) {
1313 <                    if (checkSize && tab.length < MAXIMUM_CAPACITY &&
1314 <                        resizing == 0 && counter.sum() >= (long)threshold)
1315 <                        growTable();
1312 >                if (count != 0) {
1313 >                    if (oldVal != null)
1314 >                        return oldVal;
1315 >                    if (tab.length <= 64)
1316 >                        count = 2;
1317                      break;
1318                  }
1319              }
1320          }
1321 <        if (oldVal == null)
1322 <            counter.increment();             // update counter outside of locks
1323 <        return oldVal;
1321 >        counter.add(1L);
1322 >        if (count > 1)
1323 >            checkForResize();
1324 >        return null;
1325      }
1326  
1327 <    /**
1328 <     * Implementation for the four public remove/replace methods:
586 <     * Replaces node value with v, conditional upon match of cv if
587 <     * non-null.  If resulting value is null, delete.
588 <     */
589 <    private final Object internalReplace(Object k, Object v, Object cv) {
1327 >    /** Implementation for putIfAbsent */
1328 >    private final Object internalPutIfAbsent(Object k, Object v) {
1329          int h = spread(k.hashCode());
1330 +        int count = 0;
1331          for (Node[] tab = table;;) {
1332 <            Node e; int i;
1333 <            if (tab == null ||
1334 <                (e = tabAt(tab, i = (tab.length - 1) & h)) == null)
1335 <                return null;
1336 <            else if (e.hash < 0)
1337 <                tab = (Node[])e.key;
1332 >            int i; Node f; int fh; Object fk, fv;
1333 >            if (tab == null)
1334 >                tab = initTable();
1335 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1336 >                if (casTabAt(tab, i, null, new Node(h, k, v, null)))
1337 >                    break;
1338 >            }
1339 >            else if ((fh = f.hash) == MOVED) {
1340 >                if ((fk = f.key) instanceof TreeBin) {
1341 >                    TreeBin t = (TreeBin)fk;
1342 >                    Object oldVal = null;
1343 >                    t.acquire(0);
1344 >                    try {
1345 >                        if (tabAt(tab, i) == f) {
1346 >                            count = 2;
1347 >                            TreeNode p = t.putTreeNode(h, k, v);
1348 >                            if (p != null)
1349 >                                oldVal = p.val;
1350 >                        }
1351 >                    } finally {
1352 >                        t.release(0);
1353 >                    }
1354 >                    if (count != 0) {
1355 >                        if (oldVal != null)
1356 >                            return oldVal;
1357 >                        break;
1358 >                    }
1359 >                }
1360 >                else
1361 >                    tab = (Node[])fk;
1362 >            }
1363 >            else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
1364 >                     ((fk = f.key) == k || k.equals(fk)))
1365 >                return fv;
1366              else {
1367 <                Object oldVal = null;
1368 <                boolean validated = false;
1369 <                boolean deleted = false;
1370 <                synchronized (e) {
1371 <                    if (tabAt(tab, i) == e) {
1372 <                        validated = true;
1373 <                        Node pred = null;
1374 <                        do {
1375 <                            Object ek, ev;
1376 <                            if (e.hash == h &&
1377 <                                ((ek = e.key) == k || k.equals(ek)) &&
1378 <                                ((ev = e.val) != null)) {
1379 <                                if (cv == null || cv == ev || cv.equals(ev)) {
1367 >                Node g = f.next;
1368 >                if (g != null) { // at least 2 nodes -- search and maybe resize
1369 >                    for (Node e = g;;) {
1370 >                        Object ek, ev;
1371 >                        if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
1372 >                            ((ek = e.key) == k || k.equals(ek)))
1373 >                            return ev;
1374 >                        if ((e = e.next) == null) {
1375 >                            checkForResize();
1376 >                            break;
1377 >                        }
1378 >                    }
1379 >                }
1380 >                if (((fh = f.hash) & LOCKED) != 0) {
1381 >                    checkForResize();
1382 >                    f.tryAwaitLock(tab, i);
1383 >                }
1384 >                else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1385 >                    Object oldVal = null;
1386 >                    try {
1387 >                        if (tabAt(tab, i) == f) {
1388 >                            count = 1;
1389 >                            for (Node e = f;; ++count) {
1390 >                                Object ek, ev;
1391 >                                if ((e.hash & HASH_BITS) == h &&
1392 >                                    (ev = e.val) != null &&
1393 >                                    ((ek = e.key) == k || k.equals(ek))) {
1394                                      oldVal = ev;
1395 <                                    if ((e.val = v) == null) {
1396 <                                        deleted = true;
1397 <                                        Node en = e.next;
1398 <                                        if (pred != null)
1399 <                                            pred.next = en;
1400 <                                        else
1401 <                                            setTabAt(tab, i, en);
1402 <                                    }
1395 >                                    break;
1396 >                                }
1397 >                                Node last = e;
1398 >                                if ((e = e.next) == null) {
1399 >                                    last.next = new Node(h, k, v, null);
1400 >                                    if (count >= TREE_THRESHOLD)
1401 >                                        replaceWithTreeBin(tab, i, k);
1402 >                                    break;
1403                                  }
622                                break;
1404                              }
1405 <                        } while ((e = (pred = e).next) != null);
1405 >                        }
1406 >                    } finally {
1407 >                        if (!f.casHash(fh | LOCKED, fh)) {
1408 >                            f.hash = fh;
1409 >                            synchronized (f) { f.notifyAll(); };
1410 >                        }
1411 >                    }
1412 >                    if (count != 0) {
1413 >                        if (oldVal != null)
1414 >                            return oldVal;
1415 >                        if (tab.length <= 64)
1416 >                            count = 2;
1417 >                        break;
1418                      }
626                }
627                if (validated) {
628                    if (deleted)
629                        counter.decrement();
630                    return oldVal;
1419                  }
1420              }
1421          }
1422 +        counter.add(1L);
1423 +        if (count > 1)
1424 +            checkForResize();
1425 +        return null;
1426      }
1427  
1428 <    /** Implementation for computeIfAbsent and compute. Like put, but messier. */
1429 <    @SuppressWarnings("unchecked")
1430 <    private final V internalCompute(K k,
639 <                                    MappingFunction<? super K, ? extends V> f,
640 <                                    boolean replace) {
1428 >    /** Implementation for computeIfAbsent */
1429 >    private final Object internalComputeIfAbsent(K k,
1430 >                                                 Fun<? super K, ?> mf) {
1431          int h = spread(k.hashCode());
1432 <        V val = null;
1433 <        boolean added = false;
1434 <        Node[] tab = table;
1435 <        outer:for (;;) {
646 <            Node e; int i; Object ek, ev;
1432 >        Object val = null;
1433 >        int count = 0;
1434 >        for (Node[] tab = table;;) {
1435 >            Node f; int i, fh; Object fk, fv;
1436              if (tab == null)
1437 <                tab = growTable();
1438 <            else if ((e = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1439 <                Node node = new Node(h, k, null, null);
1440 <                boolean validated = false;
1441 <                synchronized (node) {  // must lock while computing value
1442 <                    if (casTabAt(tab, i, null, node)) {
1443 <                        validated = true;
1444 <                        try {
1445 <                            val = f.map(k);
1446 <                            if (val != null) {
1447 <                                node.val = val;
1437 >                tab = initTable();
1438 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1439 >                Node node = new Node(fh = h | LOCKED, k, null, null);
1440 >                if (casTabAt(tab, i, null, node)) {
1441 >                    count = 1;
1442 >                    try {
1443 >                        if ((val = mf.apply(k)) != null)
1444 >                            node.val = val;
1445 >                    } finally {
1446 >                        if (val == null)
1447 >                            setTabAt(tab, i, null);
1448 >                        if (!node.casHash(fh, h)) {
1449 >                            node.hash = h;
1450 >                            synchronized (node) { node.notifyAll(); };
1451 >                        }
1452 >                    }
1453 >                }
1454 >                if (count != 0)
1455 >                    break;
1456 >            }
1457 >            else if ((fh = f.hash) == MOVED) {
1458 >                if ((fk = f.key) instanceof TreeBin) {
1459 >                    TreeBin t = (TreeBin)fk;
1460 >                    boolean added = false;
1461 >                    t.acquire(0);
1462 >                    try {
1463 >                        if (tabAt(tab, i) == f) {
1464 >                            count = 1;
1465 >                            TreeNode p = t.getTreeNode(h, k, t.root);
1466 >                            if (p != null)
1467 >                                val = p.val;
1468 >                            else if ((val = mf.apply(k)) != null) {
1469                                  added = true;
1470 +                                count = 2;
1471 +                                t.putTreeNode(h, k, val);
1472                              }
661                        } finally {
662                            if (!added)
663                                setTabAt(tab, i, null);
1473                          }
1474 +                    } finally {
1475 +                        t.release(0);
1476 +                    }
1477 +                    if (count != 0) {
1478 +                        if (!added)
1479 +                            return val;
1480 +                        break;
1481                      }
1482                  }
1483 <                if (validated)
1484 <                    break;
1483 >                else
1484 >                    tab = (Node[])fk;
1485              }
1486 <            else if (e.hash < 0)
1487 <                tab = (Node[])e.key;
1488 <            else if (!replace && e.hash == h && (ev = e.val) != null &&
1489 <                     ((ek = e.key) == k || k.equals(ek))) {
1490 <                if (tabAt(tab, i) == e) {
1491 <                    val = (V)ev;
1486 >            else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
1487 >                     ((fk = f.key) == k || k.equals(fk)))
1488 >                return fv;
1489 >            else {
1490 >                Node g = f.next;
1491 >                if (g != null) {
1492 >                    for (Node e = g;;) {
1493 >                        Object ek, ev;
1494 >                        if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
1495 >                            ((ek = e.key) == k || k.equals(ek)))
1496 >                            return ev;
1497 >                        if ((e = e.next) == null) {
1498 >                            checkForResize();
1499 >                            break;
1500 >                        }
1501 >                    }
1502 >                }
1503 >                if (((fh = f.hash) & LOCKED) != 0) {
1504 >                    checkForResize();
1505 >                    f.tryAwaitLock(tab, i);
1506 >                }
1507 >                else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1508 >                    boolean added = false;
1509 >                    try {
1510 >                        if (tabAt(tab, i) == f) {
1511 >                            count = 1;
1512 >                            for (Node e = f;; ++count) {
1513 >                                Object ek, ev;
1514 >                                if ((e.hash & HASH_BITS) == h &&
1515 >                                    (ev = e.val) != null &&
1516 >                                    ((ek = e.key) == k || k.equals(ek))) {
1517 >                                    val = ev;
1518 >                                    break;
1519 >                                }
1520 >                                Node last = e;
1521 >                                if ((e = e.next) == null) {
1522 >                                    if ((val = mf.apply(k)) != null) {
1523 >                                        added = true;
1524 >                                        last.next = new Node(h, k, val, null);
1525 >                                        if (count >= TREE_THRESHOLD)
1526 >                                            replaceWithTreeBin(tab, i, k);
1527 >                                    }
1528 >                                    break;
1529 >                                }
1530 >                            }
1531 >                        }
1532 >                    } finally {
1533 >                        if (!f.casHash(fh | LOCKED, fh)) {
1534 >                            f.hash = fh;
1535 >                            synchronized (f) { f.notifyAll(); };
1536 >                        }
1537 >                    }
1538 >                    if (count != 0) {
1539 >                        if (!added)
1540 >                            return val;
1541 >                        if (tab.length <= 64)
1542 >                            count = 2;
1543 >                        break;
1544 >                    }
1545 >                }
1546 >            }
1547 >        }
1548 >        if (val != null) {
1549 >            counter.add(1L);
1550 >            if (count > 1)
1551 >                checkForResize();
1552 >        }
1553 >        return val;
1554 >    }
1555 >
1556 >    /** Implementation for compute */
1557 >    @SuppressWarnings("unchecked") private final Object internalCompute
1558 >        (K k, boolean onlyIfPresent, BiFun<? super K, ? super V, ? extends V> mf) {
1559 >        int h = spread(k.hashCode());
1560 >        Object val = null;
1561 >        int delta = 0;
1562 >        int count = 0;
1563 >        for (Node[] tab = table;;) {
1564 >            Node f; int i, fh; Object fk;
1565 >            if (tab == null)
1566 >                tab = initTable();
1567 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1568 >                if (onlyIfPresent)
1569                      break;
1570 +                Node node = new Node(fh = h | LOCKED, k, null, null);
1571 +                if (casTabAt(tab, i, null, node)) {
1572 +                    try {
1573 +                        count = 1;
1574 +                        if ((val = mf.apply(k, null)) != null) {
1575 +                            node.val = val;
1576 +                            delta = 1;
1577 +                        }
1578 +                    } finally {
1579 +                        if (delta == 0)
1580 +                            setTabAt(tab, i, null);
1581 +                        if (!node.casHash(fh, h)) {
1582 +                            node.hash = h;
1583 +                            synchronized (node) { node.notifyAll(); };
1584 +                        }
1585 +                    }
1586                  }
1587 +                if (count != 0)
1588 +                    break;
1589              }
1590 <            else if (Thread.holdsLock(e))
1591 <                throw new IllegalStateException("Recursive map computation");
1592 <            else {
1593 <                boolean validated = false;
1594 <                boolean checkSize = false;
1595 <                synchronized (e) {
1596 <                    if (tabAt(tab, i) == e) {
1597 <                        validated = true;
1598 <                        for (Node first = e;;) {
1599 <                            if (e.hash == h &&
1600 <                                ((ek = e.key) == k || k.equals(ek)) &&
1601 <                                ((ev = e.val) != null)) {
1602 <                                Object fv;
1603 <                                if (replace && (fv = f.map(k)) != null)
1604 <                                    ev = e.val = fv;
1605 <                                val = (V)ev;
1590 >            else if ((fh = f.hash) == MOVED) {
1591 >                if ((fk = f.key) instanceof TreeBin) {
1592 >                    TreeBin t = (TreeBin)fk;
1593 >                    t.acquire(0);
1594 >                    try {
1595 >                        if (tabAt(tab, i) == f) {
1596 >                            count = 1;
1597 >                            TreeNode p = t.getTreeNode(h, k, t.root);
1598 >                            Object pv = (p == null) ? null : p.val;
1599 >                            if ((val = mf.apply(k, (V)pv)) != null) {
1600 >                                if (p != null)
1601 >                                    p.val = val;
1602 >                                else {
1603 >                                    count = 2;
1604 >                                    delta = 1;
1605 >                                    t.putTreeNode(h, k, val);
1606 >                                }
1607 >                            }
1608 >                            else if (p != null) {
1609 >                                delta = -1;
1610 >                                t.deleteTreeNode(p);
1611 >                            }
1612 >                        }
1613 >                    } finally {
1614 >                        t.release(0);
1615 >                    }
1616 >                    if (count != 0)
1617 >                        break;
1618 >                }
1619 >                else
1620 >                    tab = (Node[])fk;
1621 >            }
1622 >            else if ((fh & LOCKED) != 0) {
1623 >                checkForResize();
1624 >                f.tryAwaitLock(tab, i);
1625 >            }
1626 >            else if (f.casHash(fh, fh | LOCKED)) {
1627 >                try {
1628 >                    if (tabAt(tab, i) == f) {
1629 >                        count = 1;
1630 >                        for (Node e = f, pred = null;; ++count) {
1631 >                            Object ek, ev;
1632 >                            if ((e.hash & HASH_BITS) == h &&
1633 >                                (ev = e.val) != null &&
1634 >                                ((ek = e.key) == k || k.equals(ek))) {
1635 >                                val = mf.apply(k, (V)ev);
1636 >                                if (val != null)
1637 >                                    e.val = val;
1638 >                                else {
1639 >                                    delta = -1;
1640 >                                    Node en = e.next;
1641 >                                    if (pred != null)
1642 >                                        pred.next = en;
1643 >                                    else
1644 >                                        setTabAt(tab, i, en);
1645 >                                }
1646                                  break;
1647                              }
1648 <                            Node last = e;
1648 >                            pred = e;
1649                              if ((e = e.next) == null) {
1650 <                                if ((val = f.map(k)) != null) {
1651 <                                    last.next = new Node(h, k, val, null);
1652 <                                    added = true;
1653 <                                    if (last != first || tab.length <= 64)
1654 <                                        checkSize = true;
1650 >                                if (!onlyIfPresent && (val = mf.apply(k, null)) != null) {
1651 >                                    pred.next = new Node(h, k, val, null);
1652 >                                    delta = 1;
1653 >                                    if (count >= TREE_THRESHOLD)
1654 >                                        replaceWithTreeBin(tab, i, k);
1655                                  }
1656                                  break;
1657                              }
1658                          }
1659                      }
1660 +                } finally {
1661 +                    if (!f.casHash(fh | LOCKED, fh)) {
1662 +                        f.hash = fh;
1663 +                        synchronized (f) { f.notifyAll(); };
1664 +                    }
1665                  }
1666 <                if (validated) {
1667 <                    if (checkSize && tab.length < MAXIMUM_CAPACITY &&
1668 <                        resizing == 0 && counter.sum() >= (long)threshold)
713 <                        growTable();
1666 >                if (count != 0) {
1667 >                    if (tab.length <= 64)
1668 >                        count = 2;
1669                      break;
1670                  }
1671              }
1672          }
1673 <        if (added)
1674 <            counter.increment();
1673 >        if (delta != 0) {
1674 >            counter.add((long)delta);
1675 >            if (count > 1)
1676 >                checkForResize();
1677 >        }
1678          return val;
1679      }
1680  
1681 +    /** Implementation for merge */
1682 +    @SuppressWarnings("unchecked") private final Object internalMerge
1683 +        (K k, V v, BiFun<? super V, ? super V, ? extends V> mf) {
1684 +        int h = spread(k.hashCode());
1685 +        Object val = null;
1686 +        int delta = 0;
1687 +        int count = 0;
1688 +        for (Node[] tab = table;;) {
1689 +            int i; Node f; int fh; Object fk, fv;
1690 +            if (tab == null)
1691 +                tab = initTable();
1692 +            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1693 +                if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
1694 +                    delta = 1;
1695 +                    val = v;
1696 +                    break;
1697 +                }
1698 +            }
1699 +            else if ((fh = f.hash) == MOVED) {
1700 +                if ((fk = f.key) instanceof TreeBin) {
1701 +                    TreeBin t = (TreeBin)fk;
1702 +                    t.acquire(0);
1703 +                    try {
1704 +                        if (tabAt(tab, i) == f) {
1705 +                            count = 1;
1706 +                            TreeNode p = t.getTreeNode(h, k, t.root);
1707 +                            val = (p == null) ? v : mf.apply((V)p.val, v);
1708 +                            if (val != null) {
1709 +                                if (p != null)
1710 +                                    p.val = val;
1711 +                                else {
1712 +                                    count = 2;
1713 +                                    delta = 1;
1714 +                                    t.putTreeNode(h, k, val);
1715 +                                }
1716 +                            }
1717 +                            else if (p != null) {
1718 +                                delta = -1;
1719 +                                t.deleteTreeNode(p);
1720 +                            }
1721 +                        }
1722 +                    } finally {
1723 +                        t.release(0);
1724 +                    }
1725 +                    if (count != 0)
1726 +                        break;
1727 +                }
1728 +                else
1729 +                    tab = (Node[])fk;
1730 +            }
1731 +            else if ((fh & LOCKED) != 0) {
1732 +                checkForResize();
1733 +                f.tryAwaitLock(tab, i);
1734 +            }
1735 +            else if (f.casHash(fh, fh | LOCKED)) {
1736 +                try {
1737 +                    if (tabAt(tab, i) == f) {
1738 +                        count = 1;
1739 +                        for (Node e = f, pred = null;; ++count) {
1740 +                            Object ek, ev;
1741 +                            if ((e.hash & HASH_BITS) == h &&
1742 +                                (ev = e.val) != null &&
1743 +                                ((ek = e.key) == k || k.equals(ek))) {
1744 +                                val = mf.apply(v, (V)ev);
1745 +                                if (val != null)
1746 +                                    e.val = val;
1747 +                                else {
1748 +                                    delta = -1;
1749 +                                    Node en = e.next;
1750 +                                    if (pred != null)
1751 +                                        pred.next = en;
1752 +                                    else
1753 +                                        setTabAt(tab, i, en);
1754 +                                }
1755 +                                break;
1756 +                            }
1757 +                            pred = e;
1758 +                            if ((e = e.next) == null) {
1759 +                                val = v;
1760 +                                pred.next = new Node(h, k, val, null);
1761 +                                delta = 1;
1762 +                                if (count >= TREE_THRESHOLD)
1763 +                                    replaceWithTreeBin(tab, i, k);
1764 +                                break;
1765 +                            }
1766 +                        }
1767 +                    }
1768 +                } finally {
1769 +                    if (!f.casHash(fh | LOCKED, fh)) {
1770 +                        f.hash = fh;
1771 +                        synchronized (f) { f.notifyAll(); };
1772 +                    }
1773 +                }
1774 +                if (count != 0) {
1775 +                    if (tab.length <= 64)
1776 +                        count = 2;
1777 +                    break;
1778 +                }
1779 +            }
1780 +        }
1781 +        if (delta != 0) {
1782 +            counter.add((long)delta);
1783 +            if (count > 1)
1784 +                checkForResize();
1785 +        }
1786 +        return val;
1787 +    }
1788 +
1789 +    /** Implementation for putAll */
1790 +    private final void internalPutAll(Map<?, ?> m) {
1791 +        tryPresize(m.size());
1792 +        long delta = 0L;     // number of uncommitted additions
1793 +        boolean npe = false; // to throw exception on exit for nulls
1794 +        try {                // to clean up counts on other exceptions
1795 +            for (Map.Entry<?, ?> entry : m.entrySet()) {
1796 +                Object k, v;
1797 +                if (entry == null || (k = entry.getKey()) == null ||
1798 +                    (v = entry.getValue()) == null) {
1799 +                    npe = true;
1800 +                    break;
1801 +                }
1802 +                int h = spread(k.hashCode());
1803 +                for (Node[] tab = table;;) {
1804 +                    int i; Node f; int fh; Object fk;
1805 +                    if (tab == null)
1806 +                        tab = initTable();
1807 +                    else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
1808 +                        if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
1809 +                            ++delta;
1810 +                            break;
1811 +                        }
1812 +                    }
1813 +                    else if ((fh = f.hash) == MOVED) {
1814 +                        if ((fk = f.key) instanceof TreeBin) {
1815 +                            TreeBin t = (TreeBin)fk;
1816 +                            boolean validated = false;
1817 +                            t.acquire(0);
1818 +                            try {
1819 +                                if (tabAt(tab, i) == f) {
1820 +                                    validated = true;
1821 +                                    TreeNode p = t.getTreeNode(h, k, t.root);
1822 +                                    if (p != null)
1823 +                                        p.val = v;
1824 +                                    else {
1825 +                                        t.putTreeNode(h, k, v);
1826 +                                        ++delta;
1827 +                                    }
1828 +                                }
1829 +                            } finally {
1830 +                                t.release(0);
1831 +                            }
1832 +                            if (validated)
1833 +                                break;
1834 +                        }
1835 +                        else
1836 +                            tab = (Node[])fk;
1837 +                    }
1838 +                    else if ((fh & LOCKED) != 0) {
1839 +                        counter.add(delta);
1840 +                        delta = 0L;
1841 +                        checkForResize();
1842 +                        f.tryAwaitLock(tab, i);
1843 +                    }
1844 +                    else if (f.casHash(fh, fh | LOCKED)) {
1845 +                        int count = 0;
1846 +                        try {
1847 +                            if (tabAt(tab, i) == f) {
1848 +                                count = 1;
1849 +                                for (Node e = f;; ++count) {
1850 +                                    Object ek, ev;
1851 +                                    if ((e.hash & HASH_BITS) == h &&
1852 +                                        (ev = e.val) != null &&
1853 +                                        ((ek = e.key) == k || k.equals(ek))) {
1854 +                                        e.val = v;
1855 +                                        break;
1856 +                                    }
1857 +                                    Node last = e;
1858 +                                    if ((e = e.next) == null) {
1859 +                                        ++delta;
1860 +                                        last.next = new Node(h, k, v, null);
1861 +                                        if (count >= TREE_THRESHOLD)
1862 +                                            replaceWithTreeBin(tab, i, k);
1863 +                                        break;
1864 +                                    }
1865 +                                }
1866 +                            }
1867 +                        } finally {
1868 +                            if (!f.casHash(fh | LOCKED, fh)) {
1869 +                                f.hash = fh;
1870 +                                synchronized (f) { f.notifyAll(); };
1871 +                            }
1872 +                        }
1873 +                        if (count != 0) {
1874 +                            if (count > 1) {
1875 +                                counter.add(delta);
1876 +                                delta = 0L;
1877 +                                checkForResize();
1878 +                            }
1879 +                            break;
1880 +                        }
1881 +                    }
1882 +                }
1883 +            }
1884 +        } finally {
1885 +            if (delta != 0)
1886 +                counter.add(delta);
1887 +        }
1888 +        if (npe)
1889 +            throw new NullPointerException();
1890 +    }
1891 +
1892 +    /* ---------------- Table Initialization and Resizing -------------- */
1893 +
1894      /**
1895 <     * Implementation for clear. Steps through each bin, removing all nodes.
1895 >     * Returns a power of two table size for the given desired capacity.
1896 >     * See Hackers Delight, sec 3.2
1897 >     */
1898 >    private static final int tableSizeFor(int c) {
1899 >        int n = c - 1;
1900 >        n |= n >>> 1;
1901 >        n |= n >>> 2;
1902 >        n |= n >>> 4;
1903 >        n |= n >>> 8;
1904 >        n |= n >>> 16;
1905 >        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
1906 >    }
1907 >
1908 >    /**
1909 >     * Initializes table, using the size recorded in sizeCtl.
1910 >     */
1911 >    private final Node[] initTable() {
1912 >        Node[] tab; int sc;
1913 >        while ((tab = table) == null) {
1914 >            if ((sc = sizeCtl) < 0)
1915 >                Thread.yield(); // lost initialization race; just spin
1916 >            else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1917 >                try {
1918 >                    if ((tab = table) == null) {
1919 >                        int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
1920 >                        tab = table = new Node[n];
1921 >                        sc = n - (n >>> 2);
1922 >                    }
1923 >                } finally {
1924 >                    sizeCtl = sc;
1925 >                }
1926 >                break;
1927 >            }
1928 >        }
1929 >        return tab;
1930 >    }
1931 >
1932 >    /**
1933 >     * If table is too small and not already resizing, creates next
1934 >     * table and transfers bins.  Rechecks occupancy after a transfer
1935 >     * to see if another resize is already needed because resizings
1936 >     * are lagging additions.
1937 >     */
1938 >    private final void checkForResize() {
1939 >        Node[] tab; int n, sc;
1940 >        while ((tab = table) != null &&
1941 >               (n = tab.length) < MAXIMUM_CAPACITY &&
1942 >               (sc = sizeCtl) >= 0 && counter.sum() >= (long)sc &&
1943 >               UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1944 >            try {
1945 >                if (tab == table) {
1946 >                    table = rebuild(tab);
1947 >                    sc = (n << 1) - (n >>> 1);
1948 >                }
1949 >            } finally {
1950 >                sizeCtl = sc;
1951 >            }
1952 >        }
1953 >    }
1954 >
1955 >    /**
1956 >     * Tries to presize table to accommodate the given number of elements.
1957 >     *
1958 >     * @param size number of elements (doesn't need to be perfectly accurate)
1959 >     */
1960 >    private final void tryPresize(int size) {
1961 >        int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1962 >            tableSizeFor(size + (size >>> 1) + 1);
1963 >        int sc;
1964 >        while ((sc = sizeCtl) >= 0) {
1965 >            Node[] tab = table; int n;
1966 >            if (tab == null || (n = tab.length) == 0) {
1967 >                n = (sc > c) ? sc : c;
1968 >                if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1969 >                    try {
1970 >                        if (table == tab) {
1971 >                            table = new Node[n];
1972 >                            sc = n - (n >>> 2);
1973 >                        }
1974 >                    } finally {
1975 >                        sizeCtl = sc;
1976 >                    }
1977 >                }
1978 >            }
1979 >            else if (c <= sc || n >= MAXIMUM_CAPACITY)
1980 >                break;
1981 >            else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1982 >                try {
1983 >                    if (table == tab) {
1984 >                        table = rebuild(tab);
1985 >                        sc = (n << 1) - (n >>> 1);
1986 >                    }
1987 >                } finally {
1988 >                    sizeCtl = sc;
1989 >                }
1990 >            }
1991 >        }
1992 >    }
1993 >
1994 >    /*
1995 >     * Moves and/or copies the nodes in each bin to new table. See
1996 >     * above for explanation.
1997 >     *
1998 >     * @return the new table
1999 >     */
2000 >    private static final Node[] rebuild(Node[] tab) {
2001 >        int n = tab.length;
2002 >        Node[] nextTab = new Node[n << 1];
2003 >        Node fwd = new Node(MOVED, nextTab, null, null);
2004 >        int[] buffer = null;       // holds bins to revisit; null until needed
2005 >        Node rev = null;           // reverse forwarder; null until needed
2006 >        int nbuffered = 0;         // the number of bins in buffer list
2007 >        int bufferIndex = 0;       // buffer index of current buffered bin
2008 >        int bin = n - 1;           // current non-buffered bin or -1 if none
2009 >
2010 >        for (int i = bin;;) {      // start upwards sweep
2011 >            int fh; Node f;
2012 >            if ((f = tabAt(tab, i)) == null) {
2013 >                if (bin >= 0) {    // Unbuffered; no lock needed (or available)
2014 >                    if (!casTabAt(tab, i, f, fwd))
2015 >                        continue;
2016 >                }
2017 >                else {             // transiently use a locked forwarding node
2018 >                    Node g = new Node(MOVED|LOCKED, nextTab, null, null);
2019 >                    if (!casTabAt(tab, i, f, g))
2020 >                        continue;
2021 >                    setTabAt(nextTab, i, null);
2022 >                    setTabAt(nextTab, i + n, null);
2023 >                    setTabAt(tab, i, fwd);
2024 >                    if (!g.casHash(MOVED|LOCKED, MOVED)) {
2025 >                        g.hash = MOVED;
2026 >                        synchronized (g) { g.notifyAll(); }
2027 >                    }
2028 >                }
2029 >            }
2030 >            else if ((fh = f.hash) == MOVED) {
2031 >                Object fk = f.key;
2032 >                if (fk instanceof TreeBin) {
2033 >                    TreeBin t = (TreeBin)fk;
2034 >                    boolean validated = false;
2035 >                    t.acquire(0);
2036 >                    try {
2037 >                        if (tabAt(tab, i) == f) {
2038 >                            validated = true;
2039 >                            splitTreeBin(nextTab, i, t);
2040 >                            setTabAt(tab, i, fwd);
2041 >                        }
2042 >                    } finally {
2043 >                        t.release(0);
2044 >                    }
2045 >                    if (!validated)
2046 >                        continue;
2047 >                }
2048 >            }
2049 >            else if ((fh & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) {
2050 >                boolean validated = false;
2051 >                try {              // split to lo and hi lists; copying as needed
2052 >                    if (tabAt(tab, i) == f) {
2053 >                        validated = true;
2054 >                        splitBin(nextTab, i, f);
2055 >                        setTabAt(tab, i, fwd);
2056 >                    }
2057 >                } finally {
2058 >                    if (!f.casHash(fh | LOCKED, fh)) {
2059 >                        f.hash = fh;
2060 >                        synchronized (f) { f.notifyAll(); };
2061 >                    }
2062 >                }
2063 >                if (!validated)
2064 >                    continue;
2065 >            }
2066 >            else {
2067 >                if (buffer == null) // initialize buffer for revisits
2068 >                    buffer = new int[TRANSFER_BUFFER_SIZE];
2069 >                if (bin < 0 && bufferIndex > 0) {
2070 >                    int j = buffer[--bufferIndex];
2071 >                    buffer[bufferIndex] = i;
2072 >                    i = j;         // swap with another bin
2073 >                    continue;
2074 >                }
2075 >                if (bin < 0 || nbuffered >= TRANSFER_BUFFER_SIZE) {
2076 >                    f.tryAwaitLock(tab, i);
2077 >                    continue;      // no other options -- block
2078 >                }
2079 >                if (rev == null)   // initialize reverse-forwarder
2080 >                    rev = new Node(MOVED, tab, null, null);
2081 >                if (tabAt(tab, i) != f || (f.hash & LOCKED) == 0)
2082 >                    continue;      // recheck before adding to list
2083 >                buffer[nbuffered++] = i;
2084 >                setTabAt(nextTab, i, rev);     // install place-holders
2085 >                setTabAt(nextTab, i + n, rev);
2086 >            }
2087 >
2088 >            if (bin > 0)
2089 >                i = --bin;
2090 >            else if (buffer != null && nbuffered > 0) {
2091 >                bin = -1;
2092 >                i = buffer[bufferIndex = --nbuffered];
2093 >            }
2094 >            else
2095 >                return nextTab;
2096 >        }
2097 >    }
2098 >
2099 >    /**
2100 >     * Splits a normal bin with list headed by e into lo and hi parts;
2101 >     * installs in given table.
2102 >     */
2103 >    private static void splitBin(Node[] nextTab, int i, Node e) {
2104 >        int bit = nextTab.length >>> 1; // bit to split on
2105 >        int runBit = e.hash & bit;
2106 >        Node lastRun = e, lo = null, hi = null;
2107 >        for (Node p = e.next; p != null; p = p.next) {
2108 >            int b = p.hash & bit;
2109 >            if (b != runBit) {
2110 >                runBit = b;
2111 >                lastRun = p;
2112 >            }
2113 >        }
2114 >        if (runBit == 0)
2115 >            lo = lastRun;
2116 >        else
2117 >            hi = lastRun;
2118 >        for (Node p = e; p != lastRun; p = p.next) {
2119 >            int ph = p.hash & HASH_BITS;
2120 >            Object pk = p.key, pv = p.val;
2121 >            if ((ph & bit) == 0)
2122 >                lo = new Node(ph, pk, pv, lo);
2123 >            else
2124 >                hi = new Node(ph, pk, pv, hi);
2125 >        }
2126 >        setTabAt(nextTab, i, lo);
2127 >        setTabAt(nextTab, i + bit, hi);
2128 >    }
2129 >
2130 >    /**
2131 >     * Splits a tree bin into lo and hi parts; installs in given table.
2132 >     */
2133 >    private static void splitTreeBin(Node[] nextTab, int i, TreeBin t) {
2134 >        int bit = nextTab.length >>> 1;
2135 >        TreeBin lt = new TreeBin();
2136 >        TreeBin ht = new TreeBin();
2137 >        int lc = 0, hc = 0;
2138 >        for (Node e = t.first; e != null; e = e.next) {
2139 >            int h = e.hash & HASH_BITS;
2140 >            Object k = e.key, v = e.val;
2141 >            if ((h & bit) == 0) {
2142 >                ++lc;
2143 >                lt.putTreeNode(h, k, v);
2144 >            }
2145 >            else {
2146 >                ++hc;
2147 >                ht.putTreeNode(h, k, v);
2148 >            }
2149 >        }
2150 >        Node ln, hn; // throw away trees if too small
2151 >        if (lc <= (TREE_THRESHOLD >>> 1)) {
2152 >            ln = null;
2153 >            for (Node p = lt.first; p != null; p = p.next)
2154 >                ln = new Node(p.hash, p.key, p.val, ln);
2155 >        }
2156 >        else
2157 >            ln = new Node(MOVED, lt, null, null);
2158 >        setTabAt(nextTab, i, ln);
2159 >        if (hc <= (TREE_THRESHOLD >>> 1)) {
2160 >            hn = null;
2161 >            for (Node p = ht.first; p != null; p = p.next)
2162 >                hn = new Node(p.hash, p.key, p.val, hn);
2163 >        }
2164 >        else
2165 >            hn = new Node(MOVED, ht, null, null);
2166 >        setTabAt(nextTab, i + bit, hn);
2167 >    }
2168 >
2169 >    /**
2170 >     * Implementation for clear. Steps through each bin, removing all
2171 >     * nodes.
2172       */
2173      private final void internalClear() {
2174          long delta = 0L; // negative number of deletions
2175          int i = 0;
2176          Node[] tab = table;
2177          while (tab != null && i < tab.length) {
2178 <            Node e = tabAt(tab, i);
2179 <            if (e == null)
2178 >            int fh; Object fk;
2179 >            Node f = tabAt(tab, i);
2180 >            if (f == null)
2181                  ++i;
2182 <            else if (e.hash < 0)
2183 <                tab = (Node[])e.key;
2184 <            else {
2185 <                boolean validated = false;
2186 <                synchronized (e) {
2187 <                    if (tabAt(tab, i) == e) {
2188 <                        validated = true;
2189 <                        Node en;
2190 <                        do {
2191 <                            en = e.next;
2192 <                            if (e.val != null) { // currently always true
2182 >            else if ((fh = f.hash) == MOVED) {
2183 >                if ((fk = f.key) instanceof TreeBin) {
2184 >                    TreeBin t = (TreeBin)fk;
2185 >                    t.acquire(0);
2186 >                    try {
2187 >                        if (tabAt(tab, i) == f) {
2188 >                            for (Node p = t.first; p != null; p = p.next) {
2189 >                                if (p.val != null) { // (currently always true)
2190 >                                    p.val = null;
2191 >                                    --delta;
2192 >                                }
2193 >                            }
2194 >                            t.first = null;
2195 >                            t.root = null;
2196 >                            ++i;
2197 >                        }
2198 >                    } finally {
2199 >                        t.release(0);
2200 >                    }
2201 >                }
2202 >                else
2203 >                    tab = (Node[])fk;
2204 >            }
2205 >            else if ((fh & LOCKED) != 0) {
2206 >                counter.add(delta); // opportunistically update count
2207 >                delta = 0L;
2208 >                f.tryAwaitLock(tab, i);
2209 >            }
2210 >            else if (f.casHash(fh, fh | LOCKED)) {
2211 >                try {
2212 >                    if (tabAt(tab, i) == f) {
2213 >                        for (Node e = f; e != null; e = e.next) {
2214 >                            if (e.val != null) {  // (currently always true)
2215                                  e.val = null;
2216                                  --delta;
2217                              }
2218 <                        } while ((e = en) != null);
2218 >                        }
2219                          setTabAt(tab, i, null);
2220 +                        ++i;
2221 +                    }
2222 +                } finally {
2223 +                    if (!f.casHash(fh | LOCKED, fh)) {
2224 +                        f.hash = fh;
2225 +                        synchronized (f) { f.notifyAll(); };
2226                      }
2227                  }
752                if (validated)
753                    ++i;
2228              }
2229          }
2230 <        counter.add(delta);
2230 >        if (delta != 0)
2231 >            counter.add(delta);
2232      }
2233  
2234      /* ----------------Table Traversal -------------- */
2235  
2236      /**
2237       * Encapsulates traversal for methods such as containsValue; also
2238 <     * serves as a base class for other iterators.
2238 >     * serves as a base class for other iterators and bulk tasks.
2239       *
2240       * At each step, the iterator snapshots the key ("nextKey") and
2241       * value ("nextVal") of a valid node (i.e., one that, at point of
2242 <     * snapshot, has a nonnull user value). Because val fields can
2242 >     * snapshot, has a non-null user value). Because val fields can
2243       * change (including to null, indicating deletion), field nextVal
2244       * might not be accurate at point of use, but still maintains the
2245       * weak consistency property of holding a value that was once
2246       * valid.
2247       *
2248       * Internal traversals directly access these fields, as in:
2249 <     * {@code while (it.next != null) { process(nextKey); it.advance(); }}
2249 >     * {@code while (it.advance() != null) { process(it.nextKey); }}
2250       *
2251 <     * Exported iterators (subclasses of ViewIterator) extract key,
2252 <     * value, or key-value pairs as return values of Iterator.next(),
2253 <     * and encapsulate the it.next check as hasNext();
2254 <     *
2255 <     * The iterator visits each valid node that was reachable upon
2256 <     * iterator construction once. It might miss some that were added
2257 <     * to a bin after the bin was visited, which is OK wrt consistency
2258 <     * guarantees. Maintaining this property in the face of possible
2259 <     * ongoing resizes requires a fair amount of bookkeeping state
2260 <     * that is difficult to optimize away amidst volatile accesses.
2261 <     * Even so, traversal maintains reasonable throughput.
2251 >     * Exported iterators must track whether the iterator has advanced
2252 >     * (in hasNext vs next) (by setting/checking/nulling field
2253 >     * nextVal), and then extract key, value, or key-value pairs as
2254 >     * return values of next().
2255 >     *
2256 >     * The iterator visits once each still-valid node that was
2257 >     * reachable upon iterator construction. It might miss some that
2258 >     * were added to a bin after the bin was visited, which is OK wrt
2259 >     * consistency guarantees. Maintaining this property in the face
2260 >     * of possible ongoing resizes requires a fair amount of
2261 >     * bookkeeping state that is difficult to optimize away amidst
2262 >     * volatile accesses.  Even so, traversal maintains reasonable
2263 >     * throughput.
2264       *
2265       * Normally, iteration proceeds bin-by-bin traversing lists.
2266       * However, if the table has been resized, then all future steps
# Line 793 | Line 2270 | public class ConcurrentHashMapV8<K, V>
2270       * across threads, iteration terminates if a bounds checks fails
2271       * for a table read.
2272       *
2273 <     * The range-based constructor enables creation of parallel
2274 <     * range-splitting traversals. (Not yet implemented.)
2273 >     * This class extends ForkJoinTask to streamline parallel
2274 >     * iteration in bulk operations (see BulkTask). This adds only an
2275 >     * int of space overhead, which is close enough to negligible in
2276 >     * cases where it is not needed to not worry about it.  Because
2277 >     * ForkJoinTask is Serializable, but iterators need not be, we
2278 >     * need to add warning suppressions.
2279       */
2280 <    static class InternalIterator {
2280 >    @SuppressWarnings("serial") static class Traverser<K,V,R> extends ForkJoinTask<R> {
2281 >        final ConcurrentHashMapV8<K, V> map;
2282          Node next;           // the next entry to use
2283          Node last;           // the last entry used
2284          Object nextKey;      // cached key field of next
# Line 804 | Line 2286 | public class ConcurrentHashMapV8<K, V>
2286          Node[] tab;          // current table; updated if resized
2287          int index;           // index of bin to use next
2288          int baseIndex;       // current index of initial table
2289 <        final int baseLimit; // index bound for initial table
2290 <        final int baseSize;  // initial table size
2289 >        int baseLimit;       // index bound for initial table
2290 >        int baseSize;        // initial table size
2291  
2292          /** Creates iterator for all entries in the table. */
2293 <        InternalIterator(Node[] tab) {
2294 <            this.tab = tab;
2295 <            baseLimit = baseSize = (tab == null) ? 0 : tab.length;
2296 <            index = baseIndex = 0;
2297 <            next = null;
2298 <            advance();
2299 <        }
2300 <
2301 <        /** Creates iterator for the given range of the table */
2302 <        InternalIterator(Node[] tab, int lo, int hi) {
2303 <            this.tab = tab;
2304 <            baseSize = (tab == null) ? 0 : tab.length;
2305 <            baseLimit = (hi <= baseSize) ? hi : baseSize;
2306 <            index = baseIndex = lo;
2307 <            next = null;
2308 <            advance();
2293 >        Traverser(ConcurrentHashMapV8<K, V> map) {
2294 >            this.map = map;
2295 >        }
2296 >
2297 >        /** Creates iterator for split() methods */
2298 >        Traverser(Traverser<K,V,?> it) {
2299 >            ConcurrentHashMapV8<K, V> m; Node[] t;
2300 >            if ((m = this.map = it.map) == null)
2301 >                t = null;
2302 >            else if ((t = it.tab) == null && // force parent tab initialization
2303 >                     (t = it.tab = m.table) != null)
2304 >                it.baseLimit = it.baseSize = t.length;
2305 >            this.tab = t;
2306 >            this.baseSize = it.baseSize;
2307 >            it.baseLimit = this.index = this.baseIndex =
2308 >                ((this.baseLimit = it.baseLimit) + it.baseIndex + 1) >>> 1;
2309          }
2310  
2311 <        /** Advances next. See above for explanation. */
2312 <        final void advance() {
2311 >        /**
2312 >         * Advances next; returns nextVal or null if terminated.
2313 >         * See above for explanation.
2314 >         */
2315 >        final Object advance() {
2316              Node e = last = next;
2317 +            Object ev = null;
2318              outer: do {
2319 <                if (e != null)                   // pass used or skipped node
2319 >                if (e != null)                  // advance past used/skipped node
2320                      e = e.next;
2321 <                while (e == null) {              // get to next non-null bin
2322 <                    Node[] t; int b, i, n;       // checks must use locals
2323 <                    if ((b = baseIndex) >= baseLimit || (i = index) < 0 ||
2324 <                        (t = tab) == null || i >= (n = t.length))
2321 >                while (e == null) {             // get to next non-null bin
2322 >                    ConcurrentHashMapV8<K, V> m;
2323 >                    Node[] t; int b, i, n; Object ek; // checks must use locals
2324 >                    if ((t = tab) != null)
2325 >                        n = t.length;
2326 >                    else if ((m = map) != null && (t = tab = m.table) != null)
2327 >                        n = baseLimit = baseSize = t.length;
2328 >                    else
2329 >                        break outer;
2330 >                    if ((b = baseIndex) >= baseLimit ||
2331 >                        (i = index) < 0 || i >= n)
2332                          break outer;
2333 <                    else if ((e = tabAt(t, i)) != null && e.hash < 0)
2334 <                        tab = (Node[])e.key;     // restarts due to null val
2335 <                    else                         // visit upper slots if present
2336 <                        index = (i += baseSize) < n ? i : (baseIndex = b + 1);
2333 >                    if ((e = tabAt(t, i)) != null && e.hash == MOVED) {
2334 >                        if ((ek = e.key) instanceof TreeBin)
2335 >                            e = ((TreeBin)ek).first;
2336 >                        else {
2337 >                            tab = (Node[])ek;
2338 >                            continue;           // restarts due to null val
2339 >                        }
2340 >                    }                           // visit upper slots if present
2341 >                    index = (i += baseSize) < n ? i : (baseIndex = b + 1);
2342                  }
2343                  nextKey = e.key;
2344 <            } while ((nextVal = e.val) == null); // skip deleted or special nodes
2344 >            } while ((ev = e.val) == null);    // skip deleted or special nodes
2345              next = e;
2346 +            return nextVal = ev;
2347 +        }
2348 +
2349 +        public final void remove() {
2350 +            if (nextVal == null && last == null)
2351 +                advance();
2352 +            Node e = last;
2353 +            if (e == null)
2354 +                throw new IllegalStateException();
2355 +            last = null;
2356 +            map.remove(e.key);
2357 +        }
2358 +
2359 +        public final boolean hasNext() {
2360 +            return nextVal != null || advance() != null;
2361          }
2362 +
2363 +        public final boolean hasMoreElements() { return hasNext(); }
2364 +        public final void setRawResult(Object x) { }
2365 +        public R getRawResult() { return null; }
2366 +        public boolean exec() { return true; }
2367      }
2368  
2369      /* ---------------- Public operations -------------- */
2370  
2371      /**
2372 <     * Creates a new, empty map with the default initial table size (16),
2372 >     * Creates a new, empty map with the default initial table size (16).
2373       */
2374      public ConcurrentHashMapV8() {
2375          this.counter = new LongAdder();
858        this.targetCapacity = DEFAULT_CAPACITY;
2376      }
2377  
2378      /**
# Line 875 | Line 2392 | public class ConcurrentHashMapV8<K, V>
2392                     MAXIMUM_CAPACITY :
2393                     tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
2394          this.counter = new LongAdder();
2395 <        this.targetCapacity = cap;
2395 >        this.sizeCtl = cap;
2396      }
2397  
2398      /**
# Line 885 | Line 2402 | public class ConcurrentHashMapV8<K, V>
2402       */
2403      public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) {
2404          this.counter = new LongAdder();
2405 <        this.targetCapacity = DEFAULT_CAPACITY;
2406 <        putAll(m);
2405 >        this.sizeCtl = DEFAULT_CAPACITY;
2406 >        internalPutAll(m);
2407      }
2408  
2409      /**
# Line 901 | Line 2418 | public class ConcurrentHashMapV8<K, V>
2418       * establishing the initial table size
2419       * @throws IllegalArgumentException if the initial capacity of
2420       * elements is negative or the load factor is nonpositive
2421 +     *
2422 +     * @since 1.6
2423       */
2424      public ConcurrentHashMapV8(int initialCapacity, float loadFactor) {
2425          this(initialCapacity, loadFactor, 1);
# Line 931 | Line 2450 | public class ConcurrentHashMapV8<K, V>
2450          if (initialCapacity < concurrencyLevel)   // Use at least as many bins
2451              initialCapacity = concurrencyLevel;   // as estimated threads
2452          long size = (long)(1.0 + (long)initialCapacity / loadFactor);
2453 <        int cap =  ((size >= (long)MAXIMUM_CAPACITY) ?
2454 <                    MAXIMUM_CAPACITY: tableSizeFor((int)size));
2453 >        int cap = (size >= (long)MAXIMUM_CAPACITY) ?
2454 >            MAXIMUM_CAPACITY : tableSizeFor((int)size);
2455          this.counter = new LongAdder();
2456 <        this.targetCapacity = cap;
2456 >        this.sizeCtl = cap;
2457      }
2458  
2459      /**
# Line 955 | Line 2474 | public class ConcurrentHashMapV8<K, V>
2474      }
2475  
2476      /**
2477 +     * Returns the number of mappings. This method should be used
2478 +     * instead of {@link #size} because a ConcurrentHashMap may
2479 +     * contain more mappings than can be represented as an int. The
2480 +     * value returned is a snapshot; the actual count may differ if
2481 +     * there are ongoing concurrent insertions or removals.
2482 +     *
2483 +     * @return the number of mappings
2484 +     */
2485 +    public long mappingCount() {
2486 +        long n = counter.sum();
2487 +        return (n < 0L) ? 0L : n; // ignore transient negative values
2488 +    }
2489 +
2490 +    /**
2491       * Returns the value to which the specified key is mapped,
2492       * or {@code null} if this map contains no mapping for the key.
2493       *
# Line 965 | Line 2498 | public class ConcurrentHashMapV8<K, V>
2498       *
2499       * @throws NullPointerException if the specified key is null
2500       */
2501 <    @SuppressWarnings("unchecked")
969 <    public V get(Object key) {
2501 >    @SuppressWarnings("unchecked") public V get(Object key) {
2502          if (key == null)
2503              throw new NullPointerException();
2504          return (V)internalGet(key);
2505      }
2506  
2507      /**
2508 +     * Returns the value to which the specified key is mapped,
2509 +     * or the given defaultValue if this map contains no mapping for the key.
2510 +     *
2511 +     * @param key the key
2512 +     * @param defaultValue the value to return if this map contains
2513 +     * no mapping for the given key
2514 +     * @return the mapping for the key, if present; else the defaultValue
2515 +     * @throws NullPointerException if the specified key is null
2516 +     */
2517 +    @SuppressWarnings("unchecked") public V getValueOrDefault(Object key, V defaultValue) {
2518 +        if (key == null)
2519 +            throw new NullPointerException();
2520 +        V v = (V) internalGet(key);
2521 +        return v == null ? defaultValue : v;
2522 +    }
2523 +
2524 +    /**
2525       * Tests if the specified object is a key in this table.
2526       *
2527       * @param  key   possible key
# Line 1001 | Line 2550 | public class ConcurrentHashMapV8<K, V>
2550          if (value == null)
2551              throw new NullPointerException();
2552          Object v;
2553 <        InternalIterator it = new InternalIterator(table);
2554 <        while (it.next != null) {
2555 <            if ((v = it.nextVal) == value || value.equals(v))
2553 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
2554 >        while ((v = it.advance()) != null) {
2555 >            if (v == value || value.equals(v))
2556                  return true;
1008            it.advance();
2557          }
2558          return false;
2559      }
# Line 1042 | Line 2590 | public class ConcurrentHashMapV8<K, V>
2590       *         {@code null} if there was no mapping for {@code key}
2591       * @throws NullPointerException if the specified key or value is null
2592       */
2593 <    @SuppressWarnings("unchecked")
1046 <    public V put(K key, V value) {
2593 >    @SuppressWarnings("unchecked") public V put(K key, V value) {
2594          if (key == null || value == null)
2595              throw new NullPointerException();
2596 <        return (V)internalPut(key, value, true);
2596 >        return (V)internalPut(key, value);
2597      }
2598  
2599      /**
# Line 1056 | Line 2603 | public class ConcurrentHashMapV8<K, V>
2603       *         or {@code null} if there was no mapping for the key
2604       * @throws NullPointerException if the specified key or value is null
2605       */
2606 <    @SuppressWarnings("unchecked")
1060 <    public V putIfAbsent(K key, V value) {
2606 >    @SuppressWarnings("unchecked") public V putIfAbsent(K key, V value) {
2607          if (key == null || value == null)
2608              throw new NullPointerException();
2609 <        return (V)internalPut(key, value, false);
2609 >        return (V)internalPutIfAbsent(key, value);
2610      }
2611  
2612      /**
# Line 1071 | Line 2617 | public class ConcurrentHashMapV8<K, V>
2617       * @param m mappings to be stored in this map
2618       */
2619      public void putAll(Map<? extends K, ? extends V> m) {
2620 <        if (m == null)
1075 <            throw new NullPointerException();
1076 <        /*
1077 <         * If uninitialized, try to adjust targetCapacity to
1078 <         * accommodate the given number of elements.
1079 <         */
1080 <        if (table == null) {
1081 <            int size = m.size();
1082 <            int cap = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1083 <                tableSizeFor(size + (size >>> 1) + 1);
1084 <            if (cap > targetCapacity)
1085 <                targetCapacity = cap;
1086 <        }
1087 <        for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
1088 <            put(e.getKey(), e.getValue());
2620 >        internalPutAll(m);
2621      }
2622  
2623      /**
2624       * If the specified key is not already associated with a value,
2625 <     * computes its value using the given mappingFunction, and if
2626 <     * non-null, enters it into the map.  This is equivalent to
2627 <     *  <pre> {@code
2625 >     * computes its value using the given mappingFunction and enters
2626 >     * it into the map unless null.  This is equivalent to
2627 >     * <pre> {@code
2628       * if (map.containsKey(key))
2629       *   return map.get(key);
2630 <     * value = mappingFunction.map(key);
2630 >     * value = mappingFunction.apply(key);
2631       * if (value != null)
2632       *   map.put(key, value);
2633       * return value;}</pre>
2634       *
2635 <     * except that the action is performed atomically.  Some attempted
2636 <     * update operations on this map by other threads may be blocked
2637 <     * while computation is in progress, so the computation should be
2638 <     * short and simple, and must not attempt to update any other
2639 <     * mappings of this Map. The most appropriate usage is to
2635 >     * except that the action is performed atomically.  If the
2636 >     * function returns {@code null} no mapping is recorded. If the
2637 >     * function itself throws an (unchecked) exception, the exception
2638 >     * is rethrown to its caller, and no mapping is recorded.  Some
2639 >     * attempted update operations on this map by other threads may be
2640 >     * blocked while computation is in progress, so the computation
2641 >     * should be short and simple, and must not attempt to update any
2642 >     * other mappings of this Map. The most appropriate usage is to
2643       * construct a new object serving as an initial mapped value, or
2644       * memoized result, as in:
2645 +     *
2646       *  <pre> {@code
2647 <     * map.computeIfAbsent(key, new MappingFunction<K, V>() {
2647 >     * map.computeIfAbsent(key, new Fun<K, V>() {
2648       *   public V map(K k) { return new Value(f(k)); }});}</pre>
2649       *
2650       * @param key key with which the specified value is to be associated
2651       * @param mappingFunction the function to compute a value
2652       * @return the current (existing or computed) value associated with
2653 <     *         the specified key, or {@code null} if the computation
1118 <     *         returned {@code null}
2653 >     *         the specified key, or null if the computed value is null
2654       * @throws NullPointerException if the specified key or mappingFunction
2655       *         is null
2656       * @throws IllegalStateException if the computation detectably
# Line 1124 | Line 2659 | public class ConcurrentHashMapV8<K, V>
2659       * @throws RuntimeException or Error if the mappingFunction does so,
2660       *         in which case the mapping is left unestablished
2661       */
2662 <    public V computeIfAbsent(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2662 >    @SuppressWarnings("unchecked") public V computeIfAbsent
2663 >        (K key, Fun<? super K, ? extends V> mappingFunction) {
2664          if (key == null || mappingFunction == null)
2665              throw new NullPointerException();
2666 <        return internalCompute(key, mappingFunction, false);
2666 >        return (V)internalComputeIfAbsent(key, mappingFunction);
2667      }
2668  
2669      /**
2670 <     * Computes the value associated with the given key using the given
2671 <     * mappingFunction, and if non-null, enters it into the map.  This
1136 <     * is equivalent to
2670 >     * If the given key is present, computes a new mapping value given a key and
2671 >     * its current mapped value. This is equivalent to
2672       *  <pre> {@code
2673 <     * value = mappingFunction.map(key);
2674 <     * if (value != null)
2675 <     *   map.put(key, value);
2676 <     * else
2677 <     *   value = map.get(key);
2678 <     * return value;}</pre>
2673 >     *   if (map.containsKey(key)) {
2674 >     *     value = remappingFunction.apply(key, map.get(key));
2675 >     *     if (value != null)
2676 >     *       map.put(key, value);
2677 >     *     else
2678 >     *       map.remove(key);
2679 >     *   }
2680 >     * }</pre>
2681 >     *
2682 >     * except that the action is performed atomically.  If the
2683 >     * function returns {@code null}, the mapping is removed.  If the
2684 >     * function itself throws an (unchecked) exception, the exception
2685 >     * is rethrown to its caller, and the current mapping is left
2686 >     * unchanged.  Some attempted update operations on this map by
2687 >     * other threads may be blocked while computation is in progress,
2688 >     * so the computation should be short and simple, and must not
2689 >     * attempt to update any other mappings of this Map. For example,
2690 >     * to either create or append new messages to a value mapping:
2691       *
2692 <     * except that the action is performed atomically.  Some attempted
2693 <     * update operations on this map by other threads may be blocked
2694 <     * while computation is in progress, so the computation should be
2695 <     * short and simple, and must not attempt to update any other
2696 <     * mappings of this Map.
2692 >     * @param key key with which the specified value is to be associated
2693 >     * @param remappingFunction the function to compute a value
2694 >     * @return the new value associated with the specified key, or null if none
2695 >     * @throws NullPointerException if the specified key or remappingFunction
2696 >     *         is null
2697 >     * @throws IllegalStateException if the computation detectably
2698 >     *         attempts a recursive update to this map that would
2699 >     *         otherwise never complete
2700 >     * @throws RuntimeException or Error if the remappingFunction does so,
2701 >     *         in which case the mapping is unchanged
2702 >     */
2703 >    @SuppressWarnings("unchecked") public V computeIfPresent
2704 >        (K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) {
2705 >        if (key == null || remappingFunction == null)
2706 >            throw new NullPointerException();
2707 >        return (V)internalCompute(key, true, remappingFunction);
2708 >    }
2709 >
2710 >    /**
2711 >     * Computes a new mapping value given a key and
2712 >     * its current mapped value (or {@code null} if there is no current
2713 >     * mapping). This is equivalent to
2714 >     *  <pre> {@code
2715 >     *   value = remappingFunction.apply(key, map.get(key));
2716 >     *   if (value != null)
2717 >     *     map.put(key, value);
2718 >     *   else
2719 >     *     map.remove(key);
2720 >     * }</pre>
2721 >     *
2722 >     * except that the action is performed atomically.  If the
2723 >     * function returns {@code null}, the mapping is removed.  If the
2724 >     * function itself throws an (unchecked) exception, the exception
2725 >     * is rethrown to its caller, and the current mapping is left
2726 >     * unchanged.  Some attempted update operations on this map by
2727 >     * other threads may be blocked while computation is in progress,
2728 >     * so the computation should be short and simple, and must not
2729 >     * attempt to update any other mappings of this Map. For example,
2730 >     * to either create or append new messages to a value mapping:
2731 >     *
2732 >     * <pre> {@code
2733 >     * Map<Key, String> map = ...;
2734 >     * final String msg = ...;
2735 >     * map.compute(key, new BiFun<Key, String, String>() {
2736 >     *   public String apply(Key k, String v) {
2737 >     *    return (v == null) ? msg : v + msg;});}}</pre>
2738       *
2739       * @param key key with which the specified value is to be associated
2740 <     * @param mappingFunction the function to compute a value
2741 <     * @return the current value associated with
2742 <     *         the specified key, or {@code null} if the computation
1155 <     *         returned {@code null} and the value was not otherwise present
1156 <     * @throws NullPointerException if the specified key or mappingFunction
2740 >     * @param remappingFunction the function to compute a value
2741 >     * @return the new value associated with the specified key, or null if none
2742 >     * @throws NullPointerException if the specified key or remappingFunction
2743       *         is null
2744       * @throws IllegalStateException if the computation detectably
2745       *         attempts a recursive update to this map that would
2746       *         otherwise never complete
2747 <     * @throws RuntimeException or Error if the mappingFunction does so,
2747 >     * @throws RuntimeException or Error if the remappingFunction does so,
2748       *         in which case the mapping is unchanged
2749       */
2750 <    public V compute(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2751 <        if (key == null || mappingFunction == null)
2750 >    @SuppressWarnings("unchecked") public V compute
2751 >        (K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) {
2752 >        if (key == null || remappingFunction == null)
2753 >            throw new NullPointerException();
2754 >        return (V)internalCompute(key, false, remappingFunction);
2755 >    }
2756 >
2757 >    /**
2758 >     * If the specified key is not already associated
2759 >     * with a value, associate it with the given value.
2760 >     * Otherwise, replace the value with the results of
2761 >     * the given remapping function. This is equivalent to:
2762 >     *  <pre> {@code
2763 >     *   if (!map.containsKey(key))
2764 >     *     map.put(value);
2765 >     *   else {
2766 >     *     newValue = remappingFunction.apply(map.get(key), value);
2767 >     *     if (value != null)
2768 >     *       map.put(key, value);
2769 >     *     else
2770 >     *       map.remove(key);
2771 >     *   }
2772 >     * }</pre>
2773 >     * except that the action is performed atomically.  If the
2774 >     * function returns {@code null}, the mapping is removed.  If the
2775 >     * function itself throws an (unchecked) exception, the exception
2776 >     * is rethrown to its caller, and the current mapping is left
2777 >     * unchanged.  Some attempted update operations on this map by
2778 >     * other threads may be blocked while computation is in progress,
2779 >     * so the computation should be short and simple, and must not
2780 >     * attempt to update any other mappings of this Map.
2781 >     */
2782 >    @SuppressWarnings("unchecked") public V merge
2783 >        (K key, V value, BiFun<? super V, ? super V, ? extends V> remappingFunction) {
2784 >        if (key == null || value == null || remappingFunction == null)
2785              throw new NullPointerException();
2786 <        return internalCompute(key, mappingFunction, true);
2786 >        return (V)internalMerge(key, value, remappingFunction);
2787      }
2788  
2789      /**
# Line 1176 | Line 2795 | public class ConcurrentHashMapV8<K, V>
2795       *         {@code null} if there was no mapping for {@code key}
2796       * @throws NullPointerException if the specified key is null
2797       */
2798 <    @SuppressWarnings("unchecked")
1180 <    public V remove(Object key) {
2798 >    @SuppressWarnings("unchecked") public V remove(Object key) {
2799          if (key == null)
2800              throw new NullPointerException();
2801          return (V)internalReplace(key, null, null);
# Line 1214 | Line 2832 | public class ConcurrentHashMapV8<K, V>
2832       *         or {@code null} if there was no mapping for the key
2833       * @throws NullPointerException if the specified key or value is null
2834       */
2835 <    @SuppressWarnings("unchecked")
1218 <    public V replace(K key, V value) {
2835 >    @SuppressWarnings("unchecked") public V replace(K key, V value) {
2836          if (key == null || value == null)
2837              throw new NullPointerException();
2838          return (V)internalReplace(key, value, null);
# Line 1312 | Line 2929 | public class ConcurrentHashMapV8<K, V>
2929      }
2930  
2931      /**
2932 +     * Returns a partitionable iterator of the keys in this map.
2933 +     *
2934 +     * @return a partitionable iterator of the keys in this map
2935 +     */
2936 +    public Spliterator<K> keySpliterator() {
2937 +        return new KeyIterator<K,V>(this);
2938 +    }
2939 +
2940 +    /**
2941 +     * Returns a partitionable iterator of the values in this map.
2942 +     *
2943 +     * @return a partitionable iterator of the values in this map
2944 +     */
2945 +    public Spliterator<V> valueSpliterator() {
2946 +        return new ValueIterator<K,V>(this);
2947 +    }
2948 +
2949 +    /**
2950 +     * Returns a partitionable iterator of the entries in this map.
2951 +     *
2952 +     * @return a partitionable iterator of the entries in this map
2953 +     */
2954 +    public Spliterator<Map.Entry<K,V>> entrySpliterator() {
2955 +        return new EntryIterator<K,V>(this);
2956 +    }
2957 +
2958 +    /**
2959       * Returns the hash code value for this {@link Map}, i.e.,
2960       * the sum of, for each key-value pair in the map,
2961       * {@code key.hashCode() ^ value.hashCode()}.
# Line 1320 | Line 2964 | public class ConcurrentHashMapV8<K, V>
2964       */
2965      public int hashCode() {
2966          int h = 0;
2967 <        InternalIterator it = new InternalIterator(table);
2968 <        while (it.next != null) {
2969 <            h += it.nextKey.hashCode() ^ it.nextVal.hashCode();
2970 <            it.advance();
2967 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
2968 >        Object v;
2969 >        while ((v = it.advance()) != null) {
2970 >            h += it.nextKey.hashCode() ^ v.hashCode();
2971          }
2972          return h;
2973      }
# Line 1340 | Line 2984 | public class ConcurrentHashMapV8<K, V>
2984       * @return a string representation of this map
2985       */
2986      public String toString() {
2987 <        InternalIterator it = new InternalIterator(table);
2987 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
2988          StringBuilder sb = new StringBuilder();
2989          sb.append('{');
2990 <        if (it.next != null) {
2990 >        Object v;
2991 >        if ((v = it.advance()) != null) {
2992              for (;;) {
2993 <                Object k = it.nextKey, v = it.nextVal;
2993 >                Object k = it.nextKey;
2994                  sb.append(k == this ? "(this Map)" : k);
2995                  sb.append('=');
2996                  sb.append(v == this ? "(this Map)" : v);
2997 <                it.advance();
1353 <                if (it.next == null)
2997 >                if ((v = it.advance()) == null)
2998                      break;
2999                  sb.append(',').append(' ');
3000              }
# Line 1373 | Line 3017 | public class ConcurrentHashMapV8<K, V>
3017              if (!(o instanceof Map))
3018                  return false;
3019              Map<?,?> m = (Map<?,?>) o;
3020 <            InternalIterator it = new InternalIterator(table);
3021 <            while (it.next != null) {
3022 <                Object val = it.nextVal;
3020 >            Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3021 >            Object val;
3022 >            while ((val = it.advance()) != null) {
3023                  Object v = m.get(it.nextKey);
3024                  if (v == null || (v != val && !v.equals(val)))
3025                      return false;
1382                it.advance();
3026              }
3027              for (Map.Entry<?,?> e : m.entrySet()) {
3028                  Object mk, mv, v;
# Line 1395 | Line 3038 | public class ConcurrentHashMapV8<K, V>
3038  
3039      /* ----------------Iterators -------------- */
3040  
3041 <    /**
3042 <     * Base class for key, value, and entry iterators.  Adds a map
3043 <     * reference to InternalIterator to support Iterator.remove.
3044 <     */
3045 <    static abstract class ViewIterator<K,V> extends InternalIterator {
1403 <        final ConcurrentHashMapV8<K, V> map;
1404 <        ViewIterator(ConcurrentHashMapV8<K, V> map) {
1405 <            super(map.table);
1406 <            this.map = map;
3041 >    @SuppressWarnings("serial") static final class KeyIterator<K,V> extends Traverser<K,V,Object>
3042 >        implements Spliterator<K>, Enumeration<K> {
3043 >        KeyIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
3044 >        KeyIterator(Traverser<K,V,Object> it) {
3045 >            super(it);
3046          }
3047 <
3048 <        public final void remove() {
1410 <            if (last == null)
3047 >        public KeyIterator<K,V> split() {
3048 >            if (last != null || (next != null && nextVal == null))
3049                  throw new IllegalStateException();
3050 <            map.remove(last.key);
1413 <            last = null;
3050 >            return new KeyIterator<K,V>(this);
3051          }
3052 <
3053 <        public final boolean hasNext()         { return next != null; }
1417 <        public final boolean hasMoreElements() { return next != null; }
1418 <    }
1419 <
1420 <    static final class KeyIterator<K,V> extends ViewIterator<K,V>
1421 <        implements Iterator<K>, Enumeration<K> {
1422 <        KeyIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
1423 <
1424 <        @SuppressWarnings("unchecked")
1425 <        public final K next() {
1426 <            if (next == null)
3052 >        @SuppressWarnings("unchecked") public final K next() {
3053 >            if (nextVal == null && advance() == null)
3054                  throw new NoSuchElementException();
3055              Object k = nextKey;
3056 <            advance();
3057 <            return (K)k;
3056 >            nextVal = null;
3057 >            return (K) k;
3058          }
3059  
3060          public final K nextElement() { return next(); }
3061      }
3062  
3063 <    static final class ValueIterator<K,V> extends ViewIterator<K,V>
3064 <        implements Iterator<V>, Enumeration<V> {
3063 >    @SuppressWarnings("serial") static final class ValueIterator<K,V> extends Traverser<K,V,Object>
3064 >        implements Spliterator<V>, Enumeration<V> {
3065          ValueIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
3066 +        ValueIterator(Traverser<K,V,Object> it) {
3067 +            super(it);
3068 +        }
3069 +        public ValueIterator<K,V> split() {
3070 +            if (last != null || (next != null && nextVal == null))
3071 +                throw new IllegalStateException();
3072 +            return new ValueIterator<K,V>(this);
3073 +        }
3074  
3075 <        @SuppressWarnings("unchecked")
3076 <        public final V next() {
3077 <            if (next == null)
3075 >        @SuppressWarnings("unchecked") public final V next() {
3076 >            Object v;
3077 >            if ((v = nextVal) == null && (v = advance()) == null)
3078                  throw new NoSuchElementException();
3079 <            Object v = nextVal;
3080 <            advance();
1446 <            return (V)v;
3079 >            nextVal = null;
3080 >            return (V) v;
3081          }
3082  
3083          public final V nextElement() { return next(); }
3084      }
3085  
3086 <    static final class EntryIterator<K,V> extends ViewIterator<K,V>
3087 <        implements Iterator<Map.Entry<K,V>> {
3086 >    @SuppressWarnings("serial") static final class EntryIterator<K,V> extends Traverser<K,V,Object>
3087 >        implements Spliterator<Map.Entry<K,V>> {
3088          EntryIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
3089 +        EntryIterator(Traverser<K,V,Object> it) {
3090 +            super(it);
3091 +        }
3092 +        public EntryIterator<K,V> split() {
3093 +            if (last != null || (next != null && nextVal == null))
3094 +                throw new IllegalStateException();
3095 +            return new EntryIterator<K,V>(this);
3096 +        }
3097  
3098 <        @SuppressWarnings("unchecked")
3099 <        public final Map.Entry<K,V> next() {
3100 <            if (next == null)
3098 >        @SuppressWarnings("unchecked") public final Map.Entry<K,V> next() {
3099 >            Object v;
3100 >            if ((v = nextVal) == null && (v = advance()) == null)
3101                  throw new NoSuchElementException();
3102              Object k = nextKey;
3103 <            Object v = nextVal;
3104 <            advance();
1463 <            return new WriteThroughEntry<K,V>(map, (K)k, (V)v);
3103 >            nextVal = null;
3104 >            return new MapEntry<K,V>((K)k, (V)v, map);
3105          }
3106      }
3107  
3108      /**
3109 <     * Custom Entry class used by EntryIterator.next(), that relays
1469 <     * setValue changes to the underlying map.
3109 >     * Exported Entry for iterators
3110       */
3111 <    static final class WriteThroughEntry<K,V> implements Map.Entry<K, V> {
1472 <        final ConcurrentHashMapV8<K, V> map;
3111 >    static final class MapEntry<K,V> implements Map.Entry<K, V> {
3112          final K key; // non-null
3113          V val;       // non-null
3114 <        WriteThroughEntry(ConcurrentHashMapV8<K, V> map, K key, V val) {
3115 <            this.map = map; this.key = key; this.val = val;
3114 >        final ConcurrentHashMapV8<K, V> map;
3115 >        MapEntry(K key, V val, ConcurrentHashMapV8<K, V> map) {
3116 >            this.key = key;
3117 >            this.val = val;
3118 >            this.map = map;
3119          }
1478
3120          public final K getKey()       { return key; }
3121          public final V getValue()     { return val; }
3122          public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
# Line 1492 | Line 3133 | public class ConcurrentHashMapV8<K, V>
3133  
3134          /**
3135           * Sets our entry's value and writes through to the map. The
3136 <         * value to return is somewhat arbitrary here. Since a
3137 <         * WriteThroughEntry does not necessarily track asynchronous
3138 <         * changes, the most recent "previous" value could be
3139 <         * different from what we return (or could even have been
3140 <         * removed in which case the put will re-establish). We do not
1500 <         * and cannot guarantee more.
3136 >         * value to return is somewhat arbitrary here. Since we do not
3137 >         * necessarily track asynchronous changes, the most recent
3138 >         * "previous" value could be different from what we return (or
3139 >         * could even have been removed in which case the put will
3140 >         * re-establish). We do not and cannot guarantee more.
3141           */
3142          public final V setValue(V value) {
3143              if (value == null) throw new NullPointerException();
# Line 1510 | Line 3150 | public class ConcurrentHashMapV8<K, V>
3150  
3151      /* ----------------Views -------------- */
3152  
3153 <    /*
3154 <     * These currently just extend java.util.AbstractX classes, but
1515 <     * may need a new custom base to support partitioned traversal.
3153 >    /**
3154 >     * Base class for views.
3155       */
3156 <
1518 <    static final class KeySet<K,V> extends AbstractSet<K> {
3156 >    static abstract class CHMView<K, V> {
3157          final ConcurrentHashMapV8<K, V> map;
3158 <        KeySet(ConcurrentHashMapV8<K, V> map)   { this.map = map; }
1521 <
3158 >        CHMView(ConcurrentHashMapV8<K, V> map)  { this.map = map; }
3159          public final int size()                 { return map.size(); }
3160          public final boolean isEmpty()          { return map.isEmpty(); }
3161          public final void clear()               { map.clear(); }
3162 +
3163 +        // implementations below rely on concrete classes supplying these
3164 +        abstract public Iterator<?> iterator();
3165 +        abstract public boolean contains(Object o);
3166 +        abstract public boolean remove(Object o);
3167 +
3168 +        private static final String oomeMsg = "Required array size too large";
3169 +
3170 +        public final Object[] toArray() {
3171 +            long sz = map.mappingCount();
3172 +            if (sz > (long)(MAX_ARRAY_SIZE))
3173 +                throw new OutOfMemoryError(oomeMsg);
3174 +            int n = (int)sz;
3175 +            Object[] r = new Object[n];
3176 +            int i = 0;
3177 +            Iterator<?> it = iterator();
3178 +            while (it.hasNext()) {
3179 +                if (i == n) {
3180 +                    if (n >= MAX_ARRAY_SIZE)
3181 +                        throw new OutOfMemoryError(oomeMsg);
3182 +                    if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
3183 +                        n = MAX_ARRAY_SIZE;
3184 +                    else
3185 +                        n += (n >>> 1) + 1;
3186 +                    r = Arrays.copyOf(r, n);
3187 +                }
3188 +                r[i++] = it.next();
3189 +            }
3190 +            return (i == n) ? r : Arrays.copyOf(r, i);
3191 +        }
3192 +
3193 +        @SuppressWarnings("unchecked") public final <T> T[] toArray(T[] a) {
3194 +            long sz = map.mappingCount();
3195 +            if (sz > (long)(MAX_ARRAY_SIZE))
3196 +                throw new OutOfMemoryError(oomeMsg);
3197 +            int m = (int)sz;
3198 +            T[] r = (a.length >= m) ? a :
3199 +                (T[])java.lang.reflect.Array
3200 +                .newInstance(a.getClass().getComponentType(), m);
3201 +            int n = r.length;
3202 +            int i = 0;
3203 +            Iterator<?> it = iterator();
3204 +            while (it.hasNext()) {
3205 +                if (i == n) {
3206 +                    if (n >= MAX_ARRAY_SIZE)
3207 +                        throw new OutOfMemoryError(oomeMsg);
3208 +                    if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
3209 +                        n = MAX_ARRAY_SIZE;
3210 +                    else
3211 +                        n += (n >>> 1) + 1;
3212 +                    r = Arrays.copyOf(r, n);
3213 +                }
3214 +                r[i++] = (T)it.next();
3215 +            }
3216 +            if (a == r && i < n) {
3217 +                r[i] = null; // null-terminate
3218 +                return r;
3219 +            }
3220 +            return (i == n) ? r : Arrays.copyOf(r, i);
3221 +        }
3222 +
3223 +        public final int hashCode() {
3224 +            int h = 0;
3225 +            for (Iterator<?> it = iterator(); it.hasNext();)
3226 +                h += it.next().hashCode();
3227 +            return h;
3228 +        }
3229 +
3230 +        public final String toString() {
3231 +            StringBuilder sb = new StringBuilder();
3232 +            sb.append('[');
3233 +            Iterator<?> it = iterator();
3234 +            if (it.hasNext()) {
3235 +                for (;;) {
3236 +                    Object e = it.next();
3237 +                    sb.append(e == this ? "(this Collection)" : e);
3238 +                    if (!it.hasNext())
3239 +                        break;
3240 +                    sb.append(',').append(' ');
3241 +                }
3242 +            }
3243 +            return sb.append(']').toString();
3244 +        }
3245 +
3246 +        public final boolean containsAll(Collection<?> c) {
3247 +            if (c != this) {
3248 +                for (Iterator<?> it = c.iterator(); it.hasNext();) {
3249 +                    Object e = it.next();
3250 +                    if (e == null || !contains(e))
3251 +                        return false;
3252 +                }
3253 +            }
3254 +            return true;
3255 +        }
3256 +
3257 +        public final boolean removeAll(Collection<?> c) {
3258 +            boolean modified = false;
3259 +            for (Iterator<?> it = iterator(); it.hasNext();) {
3260 +                if (c.contains(it.next())) {
3261 +                    it.remove();
3262 +                    modified = true;
3263 +                }
3264 +            }
3265 +            return modified;
3266 +        }
3267 +
3268 +        public final boolean retainAll(Collection<?> c) {
3269 +            boolean modified = false;
3270 +            for (Iterator<?> it = iterator(); it.hasNext();) {
3271 +                if (!c.contains(it.next())) {
3272 +                    it.remove();
3273 +                    modified = true;
3274 +                }
3275 +            }
3276 +            return modified;
3277 +        }
3278 +
3279 +    }
3280 +
3281 +    static final class KeySet<K,V> extends CHMView<K,V> implements Set<K> {
3282 +        KeySet(ConcurrentHashMapV8<K, V> map)  {
3283 +            super(map);
3284 +        }
3285          public final boolean contains(Object o) { return map.containsKey(o); }
3286          public final boolean remove(Object o)   { return map.remove(o) != null; }
3287          public final Iterator<K> iterator() {
3288              return new KeyIterator<K,V>(map);
3289          }
3290 +        public final boolean add(K e) {
3291 +            throw new UnsupportedOperationException();
3292 +        }
3293 +        public final boolean addAll(Collection<? extends K> c) {
3294 +            throw new UnsupportedOperationException();
3295 +        }
3296 +        public boolean equals(Object o) {
3297 +            Set<?> c;
3298 +            return ((o instanceof Set) &&
3299 +                    ((c = (Set<?>)o) == this ||
3300 +                     (containsAll(c) && c.containsAll(this))));
3301 +        }
3302      }
3303  
1532    static final class Values<K,V> extends AbstractCollection<V> {
1533        final ConcurrentHashMapV8<K, V> map;
1534        Values(ConcurrentHashMapV8<K, V> map)   { this.map = map; }
3304  
3305 <        public final int size()                 { return map.size(); }
3306 <        public final boolean isEmpty()          { return map.isEmpty(); }
3307 <        public final void clear()               { map.clear(); }
3305 >    static final class Values<K,V> extends CHMView<K,V>
3306 >        implements Collection<V> {
3307 >        Values(ConcurrentHashMapV8<K, V> map)   { super(map); }
3308          public final boolean contains(Object o) { return map.containsValue(o); }
3309 +        public final boolean remove(Object o) {
3310 +            if (o != null) {
3311 +                Iterator<V> it = new ValueIterator<K,V>(map);
3312 +                while (it.hasNext()) {
3313 +                    if (o.equals(it.next())) {
3314 +                        it.remove();
3315 +                        return true;
3316 +                    }
3317 +                }
3318 +            }
3319 +            return false;
3320 +        }
3321          public final Iterator<V> iterator() {
3322              return new ValueIterator<K,V>(map);
3323          }
3324 <    }
3325 <
3326 <    static final class EntrySet<K,V> extends AbstractSet<Map.Entry<K,V>> {
3327 <        final ConcurrentHashMapV8<K, V> map;
3328 <        EntrySet(ConcurrentHashMapV8<K, V> map) { this.map = map; }
1548 <
1549 <        public final int size()                 { return map.size(); }
1550 <        public final boolean isEmpty()          { return map.isEmpty(); }
1551 <        public final void clear()               { map.clear(); }
1552 <        public final Iterator<Map.Entry<K,V>> iterator() {
1553 <            return new EntryIterator<K,V>(map);
3324 >        public final boolean add(V e) {
3325 >            throw new UnsupportedOperationException();
3326 >        }
3327 >        public final boolean addAll(Collection<? extends V> c) {
3328 >            throw new UnsupportedOperationException();
3329          }
3330  
3331 +    }
3332 +
3333 +    static final class EntrySet<K,V> extends CHMView<K,V>
3334 +        implements Set<Map.Entry<K,V>> {
3335 +        EntrySet(ConcurrentHashMapV8<K, V> map) { super(map); }
3336          public final boolean contains(Object o) {
3337              Object k, v, r; Map.Entry<?,?> e;
3338              return ((o instanceof Map.Entry) &&
# Line 1561 | Line 3341 | public class ConcurrentHashMapV8<K, V>
3341                      (v = e.getValue()) != null &&
3342                      (v == r || v.equals(r)));
3343          }
1564
3344          public final boolean remove(Object o) {
3345              Object k, v; Map.Entry<?,?> e;
3346              return ((o instanceof Map.Entry) &&
# Line 1569 | Line 3348 | public class ConcurrentHashMapV8<K, V>
3348                      (v = e.getValue()) != null &&
3349                      map.remove(k, v));
3350          }
3351 +        public final Iterator<Map.Entry<K,V>> iterator() {
3352 +            return new EntryIterator<K,V>(map);
3353 +        }
3354 +        public final boolean add(Entry<K,V> e) {
3355 +            throw new UnsupportedOperationException();
3356 +        }
3357 +        public final boolean addAll(Collection<? extends Entry<K,V>> c) {
3358 +            throw new UnsupportedOperationException();
3359 +        }
3360 +        public boolean equals(Object o) {
3361 +            Set<?> c;
3362 +            return ((o instanceof Set) &&
3363 +                    ((c = (Set<?>)o) == this ||
3364 +                     (containsAll(c) && c.containsAll(this))));
3365 +        }
3366      }
3367  
3368      /* ---------------- Serialization Support -------------- */
# Line 1592 | Line 3386 | public class ConcurrentHashMapV8<K, V>
3386       * for each key-value mapping, followed by a null pair.
3387       * The key-value mappings are emitted in no particular order.
3388       */
3389 <    @SuppressWarnings("unchecked")
3390 <    private void writeObject(java.io.ObjectOutputStream s)
1597 <            throws java.io.IOException {
3389 >    @SuppressWarnings("unchecked") private void writeObject(java.io.ObjectOutputStream s)
3390 >        throws java.io.IOException {
3391          if (segments == null) { // for serialization compatibility
3392              segments = (Segment<K,V>[])
3393                  new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
# Line 1602 | Line 3395 | public class ConcurrentHashMapV8<K, V>
3395                  segments[i] = new Segment<K,V>(LOAD_FACTOR);
3396          }
3397          s.defaultWriteObject();
3398 <        InternalIterator it = new InternalIterator(table);
3399 <        while (it.next != null) {
3398 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3399 >        Object v;
3400 >        while ((v = it.advance()) != null) {
3401              s.writeObject(it.nextKey);
3402 <            s.writeObject(it.nextVal);
1609 <            it.advance();
3402 >            s.writeObject(v);
3403          }
3404          s.writeObject(null);
3405          s.writeObject(null);
# Line 1617 | Line 3410 | public class ConcurrentHashMapV8<K, V>
3410       * Reconstitutes the instance from a stream (that is, deserializes it).
3411       * @param s the stream
3412       */
3413 <    @SuppressWarnings("unchecked")
3414 <    private void readObject(java.io.ObjectInputStream s)
1622 <            throws java.io.IOException, ClassNotFoundException {
3413 >    @SuppressWarnings("unchecked") private void readObject(java.io.ObjectInputStream s)
3414 >        throws java.io.IOException, ClassNotFoundException {
3415          s.defaultReadObject();
3416          this.segments = null; // unneeded
3417 <        // initalize transient final field
3417 >        // initialize transient final field
3418          UNSAFE.putObjectVolatile(this, counterOffset, new LongAdder());
1627        this.targetCapacity = DEFAULT_CAPACITY;
3419  
3420          // Create all nodes, then place in table once size is known
3421          long size = 0L;
# Line 1633 | Line 3424 | public class ConcurrentHashMapV8<K, V>
3424              K k = (K) s.readObject();
3425              V v = (V) s.readObject();
3426              if (k != null && v != null) {
3427 <                p = new Node(spread(k.hashCode()), k, v, p);
3427 >                int h = spread(k.hashCode());
3428 >                p = new Node(h, k, v, p);
3429                  ++size;
3430              }
3431              else
# Line 1641 | Line 3433 | public class ConcurrentHashMapV8<K, V>
3433          }
3434          if (p != null) {
3435              boolean init = false;
3436 <            if (resizing == 0 &&
3437 <                UNSAFE.compareAndSwapInt(this, resizingOffset, 0, 1)) {
3436 >            int n;
3437 >            if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
3438 >                n = MAXIMUM_CAPACITY;
3439 >            else {
3440 >                int sz = (int)size;
3441 >                n = tableSizeFor(sz + (sz >>> 1) + 1);
3442 >            }
3443 >            int sc = sizeCtl;
3444 >            boolean collide = false;
3445 >            if (n > sc &&
3446 >                UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
3447                  try {
3448                      if (table == null) {
3449                          init = true;
1649                        int n;
1650                        if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
1651                            n = MAXIMUM_CAPACITY;
1652                        else {
1653                            int sz = (int)size;
1654                            n = tableSizeFor(sz + (sz >>> 1) + 1);
1655                        }
1656                        threshold = n - (n >>> 2) - THRESHOLD_OFFSET;
3450                          Node[] tab = new Node[n];
3451                          int mask = n - 1;
3452                          while (p != null) {
3453                              int j = p.hash & mask;
3454                              Node next = p.next;
3455 <                            p.next = tabAt(tab, j);
3455 >                            Node q = p.next = tabAt(tab, j);
3456                              setTabAt(tab, j, p);
3457 +                            if (!collide && q != null && q.hash == p.hash)
3458 +                                collide = true;
3459                              p = next;
3460                          }
3461                          table = tab;
3462                          counter.add(size);
3463 +                        sc = n - (n >>> 2);
3464                      }
3465                  } finally {
3466 <                    resizing = 0;
3466 >                    sizeCtl = sc;
3467 >                }
3468 >                if (collide) { // rescan and convert to TreeBins
3469 >                    Node[] tab = table;
3470 >                    for (int i = 0; i < tab.length; ++i) {
3471 >                        int c = 0;
3472 >                        for (Node e = tabAt(tab, i); e != null; e = e.next) {
3473 >                            if (++c > TREE_THRESHOLD &&
3474 >                                (e.key instanceof Comparable)) {
3475 >                                replaceWithTreeBin(tab, i, e.key);
3476 >                                break;
3477 >                            }
3478 >                        }
3479 >                    }
3480                  }
3481              }
3482              if (!init) { // Can only happen if unsafely published.
3483                  while (p != null) {
3484 <                    internalPut(p.key, p.val, true);
3484 >                    internalPut(p.key, p.val);
3485                      p = p.next;
3486                  }
3487              }
3488          }
3489      }
3490  
3491 +
3492 +    // -------------------------------------------------------
3493 +
3494 +    // Sams
3495 +    /** Interface describing a void action of one argument */
3496 +    public interface Action<A> { void apply(A a); }
3497 +    /** Interface describing a void action of two arguments */
3498 +    public interface BiAction<A,B> { void apply(A a, B b); }
3499 +    /** Interface describing a function of one argument */
3500 +    public interface Fun<A,T> { T apply(A a); }
3501 +    /** Interface describing a function of two arguments */
3502 +    public interface BiFun<A,B,T> { T apply(A a, B b); }
3503 +    /** Interface describing a function of no arguments */
3504 +    public interface Generator<T> { T apply(); }
3505 +    /** Interface describing a function mapping its argument to a double */
3506 +    public interface ObjectToDouble<A> { double apply(A a); }
3507 +    /** Interface describing a function mapping its argument to a long */
3508 +    public interface ObjectToLong<A> { long apply(A a); }
3509 +    /** Interface describing a function mapping its argument to an int */
3510 +    public interface ObjectToInt<A> {int apply(A a); }
3511 +    /** Interface describing a function mapping two arguments to a double */
3512 +    public interface ObjectByObjectToDouble<A,B> { double apply(A a, B b); }
3513 +    /** Interface describing a function mapping two arguments to a long */
3514 +    public interface ObjectByObjectToLong<A,B> { long apply(A a, B b); }
3515 +    /** Interface describing a function mapping two arguments to an int */
3516 +    public interface ObjectByObjectToInt<A,B> {int apply(A a, B b); }
3517 +    /** Interface describing a function mapping a double to a double */
3518 +    public interface DoubleToDouble { double apply(double a); }
3519 +    /** Interface describing a function mapping a long to a long */
3520 +    public interface LongToLong { long apply(long a); }
3521 +    /** Interface describing a function mapping an int to an int */
3522 +    public interface IntToInt { int apply(int a); }
3523 +    /** Interface describing a function mapping two doubles to a double */
3524 +    public interface DoubleByDoubleToDouble { double apply(double a, double b); }
3525 +    /** Interface describing a function mapping two longs to a long */
3526 +    public interface LongByLongToLong { long apply(long a, long b); }
3527 +    /** Interface describing a function mapping two ints to an int */
3528 +    public interface IntByIntToInt { int apply(int a, int b); }
3529 +
3530 +
3531 +    // -------------------------------------------------------
3532 +
3533 +    /**
3534 +     * Returns an extended {@link Parallel} view of this map using the
3535 +     * given executor for bulk parallel operations.
3536 +     *
3537 +     * @param executor the executor
3538 +     * @return a parallel view
3539 +     */
3540 +    public Parallel parallel(ForkJoinPool executor)  {
3541 +        return new Parallel(executor);
3542 +    }
3543 +
3544 +    /**
3545 +     * An extended view of a ConcurrentHashMap supporting bulk
3546 +     * parallel operations. These operations are designed to be
3547 +     * safely, and often sensibly, applied even with maps that are
3548 +     * being concurrently updated by other threads; for example, when
3549 +     * computing a snapshot summary of the values in a shared
3550 +     * registry.  There are three kinds of operation, each with four
3551 +     * forms, accepting functions with Keys, Values, Entries, and
3552 +     * (Key, Value) arguments and/or return values. Because the
3553 +     * elements of a ConcurrentHashMap are not ordered in any
3554 +     * particular way, and may be processed in different orders in
3555 +     * different parallel executions, the correctness of supplied
3556 +     * functions should not depend on any ordering, or on any other
3557 +     * objects or values that may transiently change while computation
3558 +     * is in progress; and except for forEach actions, should ideally
3559 +     * be side-effect-free.
3560 +     *
3561 +     * <ul>
3562 +     * <li> forEach: Perform a given action on each element.
3563 +     * A variant form applies a given transformation on each element
3564 +     * before performing the action.</li>
3565 +     *
3566 +     * <li> search: Return the first available non-null result of
3567 +     * applying a given function on each element; skipping further
3568 +     * search when a result is found.</li>
3569 +     *
3570 +     * <li> reduce: Accumulate each element.  The supplied reduction
3571 +     * function cannot rely on ordering (more formally, it should be
3572 +     * both associative and commutative).  There are five variants:
3573 +     *
3574 +     * <ul>
3575 +     *
3576 +     * <li> Plain reductions. (There is not a form of this method for
3577 +     * (key, value) function arguments since there is no corresponding
3578 +     * return type.)</li>
3579 +     *
3580 +     * <li> Mapped reductions that accumulate the results of a given
3581 +     * function applied to each element.</li>
3582 +     *
3583 +     * <li> Reductions to scalar doubles, longs, and ints, using a
3584 +     * given basis value.</li>
3585 +     *
3586 +     * </li>
3587 +     * </ul>
3588 +     * </ul>
3589 +     *
3590 +     * <p>The concurrency properties of the bulk operations follow
3591 +     * from those of ConcurrentHashMap: Any non-null result returned
3592 +     * from {@code get(key)} and related access methods bears a
3593 +     * happens-before relation with the associated insertion or
3594 +     * update.  The result of any bulk operation reflects the
3595 +     * composition of these per-element relations (but is not
3596 +     * necessarily atomic with respect to the map as a whole unless it
3597 +     * is somehow known to be quiescent).  Conversely, because keys
3598 +     * and values in the map are never null, null serves as a reliable
3599 +     * atomic indicator of the current lack of any result.  To
3600 +     * maintain this property, null serves as an implicit basis for
3601 +     * all non-scalar reduction operations. For the double, long, and
3602 +     * int versions, the basis should be one that, when combined with
3603 +     * any other value, returns that other value (more formally, it
3604 +     * should be the identity element for the reduction). Most common
3605 +     * reductions have these properties; for example, computing a sum
3606 +     * with basis 0 or a minimum with basis MAX_VALUE.
3607 +     *
3608 +     * <p>Search and transformation functions provided as arguments
3609 +     * should similarly return null to indicate the lack of any result
3610 +     * (in which case it is not used). In the case of mapped
3611 +     * reductions, this also enables transformations to serve as
3612 +     * filters, returning null (or, in the case of primitive
3613 +     * specializations, the identity basis) if the element should not
3614 +     * be combined. You can create compound transformations and
3615 +     * filterings by composing them yourself under this "null means
3616 +     * there is nothing there now" rule before using them in search or
3617 +     * reduce operations.
3618 +     *
3619 +     * <p>Methods accepting and/or returning Entry arguments maintain
3620 +     * key-value associations. They may be useful for example when
3621 +     * finding the key for the greatest value. Note that "plain" Entry
3622 +     * arguments can be supplied using {@code new
3623 +     * AbstractMap.SimpleEntry(k,v)}.
3624 +     *
3625 +     * <p> Bulk operations may complete abruptly, throwing an
3626 +     * exception encountered in the application of a supplied
3627 +     * function. Bear in mind when handling such exceptions that other
3628 +     * concurrently executing functions could also have thrown
3629 +     * exceptions, or would have done so if the first exception had
3630 +     * not occurred.
3631 +     *
3632 +     * <p>Parallel speedups compared to sequential processing are
3633 +     * common but not guaranteed.  Operations involving brief
3634 +     * functions on small maps may execute more slowly than sequential
3635 +     * loops if the underlying work to parallelize the computation is
3636 +     * more expensive than the computation itself. Similarly,
3637 +     * parallelization may not lead to much actual parallelism if all
3638 +     * processors are busy performing unrelated tasks.
3639 +     *
3640 +     * <p> All arguments to all task methods must be non-null.
3641 +     *
3642 +     * <p><em>jsr166e note: During transition, this class
3643 +     * uses nested functional interfaces with different names but the
3644 +     * same forms as those expected for JDK8.<em>
3645 +     */
3646 +    public class Parallel {
3647 +        final ForkJoinPool fjp;
3648 +
3649 +        /**
3650 +         * Returns an extended view of this map using the given
3651 +         * executor for bulk parallel operations.
3652 +         *
3653 +         * @param executor the executor
3654 +         */
3655 +        public Parallel(ForkJoinPool executor)  {
3656 +            this.fjp = executor;
3657 +        }
3658 +
3659 +        /**
3660 +         * Performs the given action for each (key, value).
3661 +         *
3662 +         * @param action the action
3663 +         */
3664 +        public void forEach(BiAction<K,V> action) {
3665 +            fjp.invoke(ForkJoinTasks.forEach
3666 +                       (ConcurrentHashMapV8.this, action));
3667 +        }
3668 +
3669 +        /**
3670 +         * Performs the given action for each non-null transformation
3671 +         * of each (key, value).
3672 +         *
3673 +         * @param transformer a function returning the transformation
3674 +         * for an element, or null if there is no transformation (in
3675 +         * which case the action is not applied)
3676 +         * @param action the action
3677 +         */
3678 +        public <U> void forEach(BiFun<? super K, ? super V, ? extends U> transformer,
3679 +                                Action<U> action) {
3680 +            fjp.invoke(ForkJoinTasks.forEach
3681 +                       (ConcurrentHashMapV8.this, transformer, action));
3682 +        }
3683 +
3684 +        /**
3685 +         * Returns a non-null result from applying the given search
3686 +         * function on each (key, value), or null if none.  Upon
3687 +         * success, further element processing is suppressed and the
3688 +         * results of any other parallel invocations of the search
3689 +         * function are ignored.
3690 +         *
3691 +         * @param searchFunction a function returning a non-null
3692 +         * result on success, else null
3693 +         * @return a non-null result from applying the given search
3694 +         * function on each (key, value), or null if none
3695 +         */
3696 +        public <U> U search(BiFun<? super K, ? super V, ? extends U> searchFunction) {
3697 +            return fjp.invoke(ForkJoinTasks.search
3698 +                              (ConcurrentHashMapV8.this, searchFunction));
3699 +        }
3700 +
3701 +        /**
3702 +         * Returns the result of accumulating the given transformation
3703 +         * of all (key, value) pairs using the given reducer to
3704 +         * combine values, or null if none.
3705 +         *
3706 +         * @param transformer a function returning the transformation
3707 +         * for an element, or null if there is no transformation (in
3708 +         * which case it is not combined)
3709 +         * @param reducer a commutative associative combining function
3710 +         * @return the result of accumulating the given transformation
3711 +         * of all (key, value) pairs
3712 +         */
3713 +        public <U> U reduce(BiFun<? super K, ? super V, ? extends U> transformer,
3714 +                            BiFun<? super U, ? super U, ? extends U> reducer) {
3715 +            return fjp.invoke(ForkJoinTasks.reduce
3716 +                              (ConcurrentHashMapV8.this, transformer, reducer));
3717 +        }
3718 +
3719 +        /**
3720 +         * Returns the result of accumulating the given transformation
3721 +         * of all (key, value) pairs using the given reducer to
3722 +         * combine values, and the given basis as an identity value.
3723 +         *
3724 +         * @param transformer a function returning the transformation
3725 +         * for an element
3726 +         * @param basis the identity (initial default value) for the reduction
3727 +         * @param reducer a commutative associative combining function
3728 +         * @return the result of accumulating the given transformation
3729 +         * of all (key, value) pairs
3730 +         */
3731 +        public double reduceToDouble(ObjectByObjectToDouble<? super K, ? super V> transformer,
3732 +                                     double basis,
3733 +                                     DoubleByDoubleToDouble reducer) {
3734 +            return fjp.invoke(ForkJoinTasks.reduceToDouble
3735 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3736 +        }
3737 +
3738 +        /**
3739 +         * Returns the result of accumulating the given transformation
3740 +         * of all (key, value) pairs using the given reducer to
3741 +         * combine values, and the given basis as an identity value.
3742 +         *
3743 +         * @param transformer a function returning the transformation
3744 +         * for an element
3745 +         * @param basis the identity (initial default value) for the reduction
3746 +         * @param reducer a commutative associative combining function
3747 +         * @return the result of accumulating the given transformation
3748 +         * of all (key, value) pairs
3749 +         */
3750 +        public long reduceToLong(ObjectByObjectToLong<? super K, ? super V> transformer,
3751 +                                 long basis,
3752 +                                 LongByLongToLong reducer) {
3753 +            return fjp.invoke(ForkJoinTasks.reduceToLong
3754 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3755 +        }
3756 +
3757 +        /**
3758 +         * Returns the result of accumulating the given transformation
3759 +         * of all (key, value) pairs using the given reducer to
3760 +         * combine values, and the given basis as an identity value.
3761 +         *
3762 +         * @param transformer a function returning the transformation
3763 +         * for an element
3764 +         * @param basis the identity (initial default value) for the reduction
3765 +         * @param reducer a commutative associative combining function
3766 +         * @return the result of accumulating the given transformation
3767 +         * of all (key, value) pairs
3768 +         */
3769 +        public int reduceToInt(ObjectByObjectToInt<? super K, ? super V> transformer,
3770 +                               int basis,
3771 +                               IntByIntToInt reducer) {
3772 +            return fjp.invoke(ForkJoinTasks.reduceToInt
3773 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3774 +        }
3775 +
3776 +        /**
3777 +         * Performs the given action for each key.
3778 +         *
3779 +         * @param action the action
3780 +         */
3781 +        public void forEachKey(Action<K> action) {
3782 +            fjp.invoke(ForkJoinTasks.forEachKey
3783 +                       (ConcurrentHashMapV8.this, action));
3784 +        }
3785 +
3786 +        /**
3787 +         * Performs the given action for each non-null transformation
3788 +         * of each key.
3789 +         *
3790 +         * @param transformer a function returning the transformation
3791 +         * for an element, or null if there is no transformation (in
3792 +         * which case the action is not applied)
3793 +         * @param action the action
3794 +         */
3795 +        public <U> void forEachKey(Fun<? super K, ? extends U> transformer,
3796 +                                   Action<U> action) {
3797 +            fjp.invoke(ForkJoinTasks.forEachKey
3798 +                       (ConcurrentHashMapV8.this, transformer, action));
3799 +        }
3800 +
3801 +        /**
3802 +         * Returns a non-null result from applying the given search
3803 +         * function on each key, or null if none. Upon success,
3804 +         * further element processing is suppressed and the results of
3805 +         * any other parallel invocations of the search function are
3806 +         * ignored.
3807 +         *
3808 +         * @param searchFunction a function returning a non-null
3809 +         * result on success, else null
3810 +         * @return a non-null result from applying the given search
3811 +         * function on each key, or null if none
3812 +         */
3813 +        public <U> U searchKeys(Fun<? super K, ? extends U> searchFunction) {
3814 +            return fjp.invoke(ForkJoinTasks.searchKeys
3815 +                              (ConcurrentHashMapV8.this, searchFunction));
3816 +        }
3817 +
3818 +        /**
3819 +         * Returns the result of accumulating all keys using the given
3820 +         * reducer to combine values, or null if none.
3821 +         *
3822 +         * @param reducer a commutative associative combining function
3823 +         * @return the result of accumulating all keys using the given
3824 +         * reducer to combine values, or null if none
3825 +         */
3826 +        public K reduceKeys(BiFun<? super K, ? super K, ? extends K> reducer) {
3827 +            return fjp.invoke(ForkJoinTasks.reduceKeys
3828 +                              (ConcurrentHashMapV8.this, reducer));
3829 +        }
3830 +
3831 +        /**
3832 +         * Returns the result of accumulating the given transformation
3833 +         * of all keys using the given reducer to combine values, or
3834 +         * null if none.
3835 +         *
3836 +         * @param transformer a function returning the transformation
3837 +         * for an element, or null if there is no transformation (in
3838 +         * which case it is not combined)
3839 +         * @param reducer a commutative associative combining function
3840 +         * @return the result of accumulating the given transformation
3841 +         * of all keys
3842 +         */
3843 +        public <U> U reduceKeys(Fun<? super K, ? extends U> transformer,
3844 +                                BiFun<? super U, ? super U, ? extends U> reducer) {
3845 +            return fjp.invoke(ForkJoinTasks.reduceKeys
3846 +                              (ConcurrentHashMapV8.this, transformer, reducer));
3847 +        }
3848 +
3849 +        /**
3850 +         * Returns the result of accumulating the given transformation
3851 +         * of all keys using the given reducer to combine values, and
3852 +         * the given basis as an identity value.
3853 +         *
3854 +         * @param transformer a function returning the transformation
3855 +         * for an element
3856 +         * @param basis the identity (initial default value) for the reduction
3857 +         * @param reducer a commutative associative combining function
3858 +         * @return  the result of accumulating the given transformation
3859 +         * of all keys
3860 +         */
3861 +        public double reduceKeysToDouble(ObjectToDouble<? super K> transformer,
3862 +                                         double basis,
3863 +                                         DoubleByDoubleToDouble reducer) {
3864 +            return fjp.invoke(ForkJoinTasks.reduceKeysToDouble
3865 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3866 +        }
3867 +
3868 +        /**
3869 +         * Returns the result of accumulating the given transformation
3870 +         * of all keys using the given reducer to combine values, and
3871 +         * the given basis as an identity value.
3872 +         *
3873 +         * @param transformer a function returning the transformation
3874 +         * for an element
3875 +         * @param basis the identity (initial default value) for the reduction
3876 +         * @param reducer a commutative associative combining function
3877 +         * @return the result of accumulating the given transformation
3878 +         * of all keys
3879 +         */
3880 +        public long reduceKeysToLong(ObjectToLong<? super K> transformer,
3881 +                                     long basis,
3882 +                                     LongByLongToLong reducer) {
3883 +            return fjp.invoke(ForkJoinTasks.reduceKeysToLong
3884 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3885 +        }
3886 +
3887 +        /**
3888 +         * Returns the result of accumulating the given transformation
3889 +         * of all keys using the given reducer to combine values, and
3890 +         * the given basis as an identity value.
3891 +         *
3892 +         * @param transformer a function returning the transformation
3893 +         * for an element
3894 +         * @param basis the identity (initial default value) for the reduction
3895 +         * @param reducer a commutative associative combining function
3896 +         * @return the result of accumulating the given transformation
3897 +         * of all keys
3898 +         */
3899 +        public int reduceKeysToInt(ObjectToInt<? super K> transformer,
3900 +                                   int basis,
3901 +                                   IntByIntToInt reducer) {
3902 +            return fjp.invoke(ForkJoinTasks.reduceKeysToInt
3903 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3904 +        }
3905 +
3906 +        /**
3907 +         * Performs the given action for each value.
3908 +         *
3909 +         * @param action the action
3910 +         */
3911 +        public void forEachValue(Action<V> action) {
3912 +            fjp.invoke(ForkJoinTasks.forEachValue
3913 +                       (ConcurrentHashMapV8.this, action));
3914 +        }
3915 +
3916 +        /**
3917 +         * Performs the given action for each non-null transformation
3918 +         * of each value.
3919 +         *
3920 +         * @param transformer a function returning the transformation
3921 +         * for an element, or null if there is no transformation (in
3922 +         * which case the action is not applied)
3923 +         */
3924 +        public <U> void forEachValue(Fun<? super V, ? extends U> transformer,
3925 +                                     Action<U> action) {
3926 +            fjp.invoke(ForkJoinTasks.forEachValue
3927 +                       (ConcurrentHashMapV8.this, transformer, action));
3928 +        }
3929 +
3930 +        /**
3931 +         * Returns a non-null result from applying the given search
3932 +         * function on each value, or null if none.  Upon success,
3933 +         * further element processing is suppressed and the results of
3934 +         * any other parallel invocations of the search function are
3935 +         * ignored.
3936 +         *
3937 +         * @param searchFunction a function returning a non-null
3938 +         * result on success, else null
3939 +         * @return a non-null result from applying the given search
3940 +         * function on each value, or null if none
3941 +         */
3942 +        public <U> U searchValues(Fun<? super V, ? extends U> searchFunction) {
3943 +            return fjp.invoke(ForkJoinTasks.searchValues
3944 +                              (ConcurrentHashMapV8.this, searchFunction));
3945 +        }
3946 +
3947 +        /**
3948 +         * Returns the result of accumulating all values using the
3949 +         * given reducer to combine values, or null if none.
3950 +         *
3951 +         * @param reducer a commutative associative combining function
3952 +         * @return  the result of accumulating all values
3953 +         */
3954 +        public V reduceValues(BiFun<? super V, ? super V, ? extends V> reducer) {
3955 +            return fjp.invoke(ForkJoinTasks.reduceValues
3956 +                              (ConcurrentHashMapV8.this, reducer));
3957 +        }
3958 +
3959 +        /**
3960 +         * Returns the result of accumulating the given transformation
3961 +         * of all values using the given reducer to combine values, or
3962 +         * null if none.
3963 +         *
3964 +         * @param transformer a function returning the transformation
3965 +         * for an element, or null if there is no transformation (in
3966 +         * which case it is not combined)
3967 +         * @param reducer a commutative associative combining function
3968 +         * @return the result of accumulating the given transformation
3969 +         * of all values
3970 +         */
3971 +        public <U> U reduceValues(Fun<? super V, ? extends U> transformer,
3972 +                                  BiFun<? super U, ? super U, ? extends U> reducer) {
3973 +            return fjp.invoke(ForkJoinTasks.reduceValues
3974 +                              (ConcurrentHashMapV8.this, transformer, reducer));
3975 +        }
3976 +
3977 +        /**
3978 +         * Returns the result of accumulating the given transformation
3979 +         * of all values using the given reducer to combine values,
3980 +         * and the given basis as an identity value.
3981 +         *
3982 +         * @param transformer a function returning the transformation
3983 +         * for an element
3984 +         * @param basis the identity (initial default value) for the reduction
3985 +         * @param reducer a commutative associative combining function
3986 +         * @return the result of accumulating the given transformation
3987 +         * of all values
3988 +         */
3989 +        public double reduceValuesToDouble(ObjectToDouble<? super V> transformer,
3990 +                                           double basis,
3991 +                                           DoubleByDoubleToDouble reducer) {
3992 +            return fjp.invoke(ForkJoinTasks.reduceValuesToDouble
3993 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
3994 +        }
3995 +
3996 +        /**
3997 +         * Returns the result of accumulating the given transformation
3998 +         * of all values using the given reducer to combine values,
3999 +         * and the given basis as an identity value.
4000 +         *
4001 +         * @param transformer a function returning the transformation
4002 +         * for an element
4003 +         * @param basis the identity (initial default value) for the reduction
4004 +         * @param reducer a commutative associative combining function
4005 +         * @return the result of accumulating the given transformation
4006 +         * of all values
4007 +         */
4008 +        public long reduceValuesToLong(ObjectToLong<? super V> transformer,
4009 +                                       long basis,
4010 +                                       LongByLongToLong reducer) {
4011 +            return fjp.invoke(ForkJoinTasks.reduceValuesToLong
4012 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
4013 +        }
4014 +
4015 +        /**
4016 +         * Returns the result of accumulating the given transformation
4017 +         * of all values using the given reducer to combine values,
4018 +         * and the given basis as an identity value.
4019 +         *
4020 +         * @param transformer a function returning the transformation
4021 +         * for an element
4022 +         * @param basis the identity (initial default value) for the reduction
4023 +         * @param reducer a commutative associative combining function
4024 +         * @return the result of accumulating the given transformation
4025 +         * of all values
4026 +         */
4027 +        public int reduceValuesToInt(ObjectToInt<? super V> transformer,
4028 +                                     int basis,
4029 +                                     IntByIntToInt reducer) {
4030 +            return fjp.invoke(ForkJoinTasks.reduceValuesToInt
4031 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
4032 +        }
4033 +
4034 +        /**
4035 +         * Performs the given action for each entry.
4036 +         *
4037 +         * @param action the action
4038 +         */
4039 +        public void forEachEntry(Action<Map.Entry<K,V>> action) {
4040 +            fjp.invoke(ForkJoinTasks.forEachEntry
4041 +                       (ConcurrentHashMapV8.this, action));
4042 +        }
4043 +
4044 +        /**
4045 +         * Performs the given action for each non-null transformation
4046 +         * of each entry.
4047 +         *
4048 +         * @param transformer a function returning the transformation
4049 +         * for an element, or null if there is no transformation (in
4050 +         * which case the action is not applied)
4051 +         * @param action the action
4052 +         */
4053 +        public <U> void forEachEntry(Fun<Map.Entry<K,V>, ? extends U> transformer,
4054 +                                     Action<U> action) {
4055 +            fjp.invoke(ForkJoinTasks.forEachEntry
4056 +                       (ConcurrentHashMapV8.this, transformer, action));
4057 +        }
4058 +
4059 +        /**
4060 +         * Returns a non-null result from applying the given search
4061 +         * function on each entry, or null if none.  Upon success,
4062 +         * further element processing is suppressed and the results of
4063 +         * any other parallel invocations of the search function are
4064 +         * ignored.
4065 +         *
4066 +         * @param searchFunction a function returning a non-null
4067 +         * result on success, else null
4068 +         * @return a non-null result from applying the given search
4069 +         * function on each entry, or null if none
4070 +         */
4071 +        public <U> U searchEntries(Fun<Map.Entry<K,V>, ? extends U> searchFunction) {
4072 +            return fjp.invoke(ForkJoinTasks.searchEntries
4073 +                              (ConcurrentHashMapV8.this, searchFunction));
4074 +        }
4075 +
4076 +        /**
4077 +         * Returns the result of accumulating all entries using the
4078 +         * given reducer to combine values, or null if none.
4079 +         *
4080 +         * @param reducer a commutative associative combining function
4081 +         * @return the result of accumulating all entries
4082 +         */
4083 +        public Map.Entry<K,V> reduceEntries(BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4084 +            return fjp.invoke(ForkJoinTasks.reduceEntries
4085 +                              (ConcurrentHashMapV8.this, reducer));
4086 +        }
4087 +
4088 +        /**
4089 +         * Returns the result of accumulating the given transformation
4090 +         * of all entries using the given reducer to combine values,
4091 +         * or null if none.
4092 +         *
4093 +         * @param transformer a function returning the transformation
4094 +         * for an element, or null if there is no transformation (in
4095 +         * which case it is not combined).
4096 +         * @param reducer a commutative associative combining function
4097 +         * @return the result of accumulating the given transformation
4098 +         * of all entries
4099 +         */
4100 +        public <U> U reduceEntries(Fun<Map.Entry<K,V>, ? extends U> transformer,
4101 +                                   BiFun<? super U, ? super U, ? extends U> reducer) {
4102 +            return fjp.invoke(ForkJoinTasks.reduceEntries
4103 +                              (ConcurrentHashMapV8.this, transformer, reducer));
4104 +        }
4105 +
4106 +        /**
4107 +         * Returns the result of accumulating the given transformation
4108 +         * of all entries using the given reducer to combine values,
4109 +         * and the given basis as an identity value.
4110 +         *
4111 +         * @param transformer a function returning the transformation
4112 +         * for an element
4113 +         * @param basis the identity (initial default value) for the reduction
4114 +         * @param reducer a commutative associative combining function
4115 +         * @return the result of accumulating the given transformation
4116 +         * of all entries
4117 +         */
4118 +        public double reduceEntriesToDouble(ObjectToDouble<Map.Entry<K,V>> transformer,
4119 +                                            double basis,
4120 +                                            DoubleByDoubleToDouble reducer) {
4121 +            return fjp.invoke(ForkJoinTasks.reduceEntriesToDouble
4122 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
4123 +        }
4124 +
4125 +        /**
4126 +         * Returns the result of accumulating the given transformation
4127 +         * of all entries using the given reducer to combine values,
4128 +         * and the given basis as an identity value.
4129 +         *
4130 +         * @param transformer a function returning the transformation
4131 +         * for an element
4132 +         * @param basis the identity (initial default value) for the reduction
4133 +         * @param reducer a commutative associative combining function
4134 +         * @return  the result of accumulating the given transformation
4135 +         * of all entries
4136 +         */
4137 +        public long reduceEntriesToLong(ObjectToLong<Map.Entry<K,V>> transformer,
4138 +                                        long basis,
4139 +                                        LongByLongToLong reducer) {
4140 +            return fjp.invoke(ForkJoinTasks.reduceEntriesToLong
4141 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
4142 +        }
4143 +
4144 +        /**
4145 +         * Returns the result of accumulating the given transformation
4146 +         * of all entries using the given reducer to combine values,
4147 +         * and the given basis as an identity value.
4148 +         *
4149 +         * @param transformer a function returning the transformation
4150 +         * for an element
4151 +         * @param basis the identity (initial default value) for the reduction
4152 +         * @param reducer a commutative associative combining function
4153 +         * @return the result of accumulating the given transformation
4154 +         * of all entries
4155 +         */
4156 +        public int reduceEntriesToInt(ObjectToInt<Map.Entry<K,V>> transformer,
4157 +                                      int basis,
4158 +                                      IntByIntToInt reducer) {
4159 +            return fjp.invoke(ForkJoinTasks.reduceEntriesToInt
4160 +                              (ConcurrentHashMapV8.this, transformer, basis, reducer));
4161 +        }
4162 +    }
4163 +
4164 +    // ---------------------------------------------------------------------
4165 +
4166 +    /**
4167 +     * Predefined tasks for performing bulk parallel operations on
4168 +     * ConcurrentHashMaps. These tasks follow the forms and rules used
4169 +     * in class {@link Parallel}. Each method has the same name, but
4170 +     * returns a task rather than invoking it. These methods may be
4171 +     * useful in custom applications such as submitting a task without
4172 +     * waiting for completion, or combining with other tasks.
4173 +     */
4174 +    public static class ForkJoinTasks {
4175 +        private ForkJoinTasks() {}
4176 +
4177 +        /**
4178 +         * Returns a task that when invoked, performs the given
4179 +         * action for each (key, value)
4180 +         *
4181 +         * @param map the map
4182 +         * @param action the action
4183 +         * @return the task
4184 +         */
4185 +        public static <K,V> ForkJoinTask<Void> forEach
4186 +            (ConcurrentHashMapV8<K,V> map,
4187 +             BiAction<K,V> action) {
4188 +            if (action == null) throw new NullPointerException();
4189 +            return new ForEachMappingTask<K,V>(map, null, -1, action);
4190 +        }
4191 +
4192 +        /**
4193 +         * Returns a task that when invoked, performs the given
4194 +         * action for each non-null transformation of each (key, value)
4195 +         *
4196 +         * @param map the map
4197 +         * @param transformer a function returning the transformation
4198 +         * for an element, or null if there is no transformation (in
4199 +         * which case the action is not applied)
4200 +         * @param action the action
4201 +         * @return the task
4202 +         */
4203 +        public static <K,V,U> ForkJoinTask<Void> forEach
4204 +            (ConcurrentHashMapV8<K,V> map,
4205 +             BiFun<? super K, ? super V, ? extends U> transformer,
4206 +             Action<U> action) {
4207 +            if (transformer == null || action == null)
4208 +                throw new NullPointerException();
4209 +            return new ForEachTransformedMappingTask<K,V,U>
4210 +                (map, null, -1, transformer, action);
4211 +        }
4212 +
4213 +        /**
4214 +         * Returns a task that when invoked, returns a non-null result
4215 +         * from applying the given search function on each (key,
4216 +         * value), or null if none. Upon success, further element
4217 +         * processing is suppressed and the results of any other
4218 +         * parallel invocations of the search function are ignored.
4219 +         *
4220 +         * @param map the map
4221 +         * @param searchFunction a function returning a non-null
4222 +         * result on success, else null
4223 +         * @return the task
4224 +         */
4225 +        public static <K,V,U> ForkJoinTask<U> search
4226 +            (ConcurrentHashMapV8<K,V> map,
4227 +             BiFun<? super K, ? super V, ? extends U> searchFunction) {
4228 +            if (searchFunction == null) throw new NullPointerException();
4229 +            return new SearchMappingsTask<K,V,U>
4230 +                (map, null, -1, searchFunction,
4231 +                 new AtomicReference<U>());
4232 +        }
4233 +
4234 +        /**
4235 +         * Returns a task that when invoked, returns the result of
4236 +         * accumulating the given transformation of all (key, value) pairs
4237 +         * using the given reducer to combine values, or null if none.
4238 +         *
4239 +         * @param map the map
4240 +         * @param transformer a function returning the transformation
4241 +         * for an element, or null if there is no transformation (in
4242 +         * which case it is not combined).
4243 +         * @param reducer a commutative associative combining function
4244 +         * @return the task
4245 +         */
4246 +        public static <K,V,U> ForkJoinTask<U> reduce
4247 +            (ConcurrentHashMapV8<K,V> map,
4248 +             BiFun<? super K, ? super V, ? extends U> transformer,
4249 +             BiFun<? super U, ? super U, ? extends U> reducer) {
4250 +            if (transformer == null || reducer == null)
4251 +                throw new NullPointerException();
4252 +            return new MapReduceMappingsTask<K,V,U>
4253 +                (map, null, -1, null, transformer, reducer);
4254 +        }
4255 +
4256 +        /**
4257 +         * Returns a task that when invoked, returns the result of
4258 +         * accumulating the given transformation of all (key, value) pairs
4259 +         * using the given reducer to combine values, and the given
4260 +         * basis as an identity value.
4261 +         *
4262 +         * @param map the map
4263 +         * @param transformer a function returning the transformation
4264 +         * for an element
4265 +         * @param basis the identity (initial default value) for the reduction
4266 +         * @param reducer a commutative associative combining function
4267 +         * @return the task
4268 +         */
4269 +        public static <K,V> ForkJoinTask<Double> reduceToDouble
4270 +            (ConcurrentHashMapV8<K,V> map,
4271 +             ObjectByObjectToDouble<? super K, ? super V> transformer,
4272 +             double basis,
4273 +             DoubleByDoubleToDouble reducer) {
4274 +            if (transformer == null || reducer == null)
4275 +                throw new NullPointerException();
4276 +            return new MapReduceMappingsToDoubleTask<K,V>
4277 +                (map, null, -1, null, transformer, basis, reducer);
4278 +        }
4279 +
4280 +        /**
4281 +         * Returns a task that when invoked, returns the result of
4282 +         * accumulating the given transformation of all (key, value) pairs
4283 +         * using the given reducer to combine values, and the given
4284 +         * basis as an identity value.
4285 +         *
4286 +         * @param map the map
4287 +         * @param transformer a function returning the transformation
4288 +         * for an element
4289 +         * @param basis the identity (initial default value) for the reduction
4290 +         * @param reducer a commutative associative combining function
4291 +         * @return the task
4292 +         */
4293 +        public static <K,V> ForkJoinTask<Long> reduceToLong
4294 +            (ConcurrentHashMapV8<K,V> map,
4295 +             ObjectByObjectToLong<? super K, ? super V> transformer,
4296 +             long basis,
4297 +             LongByLongToLong reducer) {
4298 +            if (transformer == null || reducer == null)
4299 +                throw new NullPointerException();
4300 +            return new MapReduceMappingsToLongTask<K,V>
4301 +                (map, null, -1, null, transformer, basis, reducer);
4302 +        }
4303 +
4304 +        /**
4305 +         * Returns a task that when invoked, returns the result of
4306 +         * accumulating the given transformation of all (key, value) pairs
4307 +         * using the given reducer to combine values, and the given
4308 +         * basis as an identity value.
4309 +         *
4310 +         * @param transformer a function returning the transformation
4311 +         * for an element
4312 +         * @param basis the identity (initial default value) for the reduction
4313 +         * @param reducer a commutative associative combining function
4314 +         * @return the task
4315 +         */
4316 +        public static <K,V> ForkJoinTask<Integer> reduceToInt
4317 +            (ConcurrentHashMapV8<K,V> map,
4318 +             ObjectByObjectToInt<? super K, ? super V> transformer,
4319 +             int basis,
4320 +             IntByIntToInt reducer) {
4321 +            if (transformer == null || reducer == null)
4322 +                throw new NullPointerException();
4323 +            return new MapReduceMappingsToIntTask<K,V>
4324 +                (map, null, -1, null, transformer, basis, reducer);
4325 +        }
4326 +
4327 +        /**
4328 +         * Returns a task that when invoked, performs the given action
4329 +         * for each key.
4330 +         *
4331 +         * @param map the map
4332 +         * @param action the action
4333 +         * @return the task
4334 +         */
4335 +        public static <K,V> ForkJoinTask<Void> forEachKey
4336 +            (ConcurrentHashMapV8<K,V> map,
4337 +             Action<K> action) {
4338 +            if (action == null) throw new NullPointerException();
4339 +            return new ForEachKeyTask<K,V>(map, null, -1, action);
4340 +        }
4341 +
4342 +        /**
4343 +         * Returns a task that when invoked, performs the given action
4344 +         * for each non-null transformation of each key.
4345 +         *
4346 +         * @param map the map
4347 +         * @param transformer a function returning the transformation
4348 +         * for an element, or null if there is no transformation (in
4349 +         * which case the action is not applied)
4350 +         * @param action the action
4351 +         * @return the task
4352 +         */
4353 +        public static <K,V,U> ForkJoinTask<Void> forEachKey
4354 +            (ConcurrentHashMapV8<K,V> map,
4355 +             Fun<? super K, ? extends U> transformer,
4356 +             Action<U> action) {
4357 +            if (transformer == null || action == null)
4358 +                throw new NullPointerException();
4359 +            return new ForEachTransformedKeyTask<K,V,U>
4360 +                (map, null, -1, transformer, action);
4361 +        }
4362 +
4363 +        /**
4364 +         * Returns a task that when invoked, returns a non-null result
4365 +         * from applying the given search function on each key, or
4366 +         * null if none.  Upon success, further element processing is
4367 +         * suppressed and the results of any other parallel
4368 +         * invocations of the search function are ignored.
4369 +         *
4370 +         * @param map the map
4371 +         * @param searchFunction a function returning a non-null
4372 +         * result on success, else null
4373 +         * @return the task
4374 +         */
4375 +        public static <K,V,U> ForkJoinTask<U> searchKeys
4376 +            (ConcurrentHashMapV8<K,V> map,
4377 +             Fun<? super K, ? extends U> searchFunction) {
4378 +            if (searchFunction == null) throw new NullPointerException();
4379 +            return new SearchKeysTask<K,V,U>
4380 +                (map, null, -1, searchFunction,
4381 +                 new AtomicReference<U>());
4382 +        }
4383 +
4384 +        /**
4385 +         * Returns a task that when invoked, returns the result of
4386 +         * accumulating all keys using the given reducer to combine
4387 +         * values, or null if none.
4388 +         *
4389 +         * @param map the map
4390 +         * @param reducer a commutative associative combining function
4391 +         * @return the task
4392 +         */
4393 +        public static <K,V> ForkJoinTask<K> reduceKeys
4394 +            (ConcurrentHashMapV8<K,V> map,
4395 +             BiFun<? super K, ? super K, ? extends K> reducer) {
4396 +            if (reducer == null) throw new NullPointerException();
4397 +            return new ReduceKeysTask<K,V>
4398 +                (map, null, -1, null, reducer);
4399 +        }
4400 +
4401 +        /**
4402 +         * Returns a task that when invoked, returns the result of
4403 +         * accumulating the given transformation of all keys using the given
4404 +         * reducer to combine values, or null if none.
4405 +         *
4406 +         * @param map the map
4407 +         * @param transformer a function returning the transformation
4408 +         * for an element, or null if there is no transformation (in
4409 +         * which case it is not combined).
4410 +         * @param reducer a commutative associative combining function
4411 +         * @return the task
4412 +         */
4413 +        public static <K,V,U> ForkJoinTask<U> reduceKeys
4414 +            (ConcurrentHashMapV8<K,V> map,
4415 +             Fun<? super K, ? extends U> transformer,
4416 +             BiFun<? super U, ? super U, ? extends U> reducer) {
4417 +            if (transformer == null || reducer == null)
4418 +                throw new NullPointerException();
4419 +            return new MapReduceKeysTask<K,V,U>
4420 +                (map, null, -1, null, transformer, reducer);
4421 +        }
4422 +
4423 +        /**
4424 +         * Returns a task that when invoked, returns the result of
4425 +         * accumulating the given transformation of all keys using the given
4426 +         * reducer to combine values, and the given basis as an
4427 +         * identity value.
4428 +         *
4429 +         * @param map the map
4430 +         * @param transformer a function returning the transformation
4431 +         * for an element
4432 +         * @param basis the identity (initial default value) for the reduction
4433 +         * @param reducer a commutative associative combining function
4434 +         * @return the task
4435 +         */
4436 +        public static <K,V> ForkJoinTask<Double> reduceKeysToDouble
4437 +            (ConcurrentHashMapV8<K,V> map,
4438 +             ObjectToDouble<? super K> transformer,
4439 +             double basis,
4440 +             DoubleByDoubleToDouble reducer) {
4441 +            if (transformer == null || reducer == null)
4442 +                throw new NullPointerException();
4443 +            return new MapReduceKeysToDoubleTask<K,V>
4444 +                (map, null, -1, null, transformer, basis, reducer);
4445 +        }
4446 +
4447 +        /**
4448 +         * Returns a task that when invoked, returns the result of
4449 +         * accumulating the given transformation of all keys using the given
4450 +         * reducer to combine values, and the given basis as an
4451 +         * identity value.
4452 +         *
4453 +         * @param map the map
4454 +         * @param transformer a function returning the transformation
4455 +         * for an element
4456 +         * @param basis the identity (initial default value) for the reduction
4457 +         * @param reducer a commutative associative combining function
4458 +         * @return the task
4459 +         */
4460 +        public static <K,V> ForkJoinTask<Long> reduceKeysToLong
4461 +            (ConcurrentHashMapV8<K,V> map,
4462 +             ObjectToLong<? super K> transformer,
4463 +             long basis,
4464 +             LongByLongToLong reducer) {
4465 +            if (transformer == null || reducer == null)
4466 +                throw new NullPointerException();
4467 +            return new MapReduceKeysToLongTask<K,V>
4468 +                (map, null, -1, null, transformer, basis, reducer);
4469 +        }
4470 +
4471 +        /**
4472 +         * Returns a task that when invoked, returns the result of
4473 +         * accumulating the given transformation of all keys using the given
4474 +         * reducer to combine values, and the given basis as an
4475 +         * identity value.
4476 +         *
4477 +         * @param map the map
4478 +         * @param transformer a function returning the transformation
4479 +         * for an element
4480 +         * @param basis the identity (initial default value) for the reduction
4481 +         * @param reducer a commutative associative combining function
4482 +         * @return the task
4483 +         */
4484 +        public static <K,V> ForkJoinTask<Integer> reduceKeysToInt
4485 +            (ConcurrentHashMapV8<K,V> map,
4486 +             ObjectToInt<? super K> transformer,
4487 +             int basis,
4488 +             IntByIntToInt reducer) {
4489 +            if (transformer == null || reducer == null)
4490 +                throw new NullPointerException();
4491 +            return new MapReduceKeysToIntTask<K,V>
4492 +                (map, null, -1, null, transformer, basis, reducer);
4493 +        }
4494 +
4495 +        /**
4496 +         * Returns a task that when invoked, performs the given action
4497 +         * for each value.
4498 +         *
4499 +         * @param map the map
4500 +         * @param action the action
4501 +         */
4502 +        public static <K,V> ForkJoinTask<Void> forEachValue
4503 +            (ConcurrentHashMapV8<K,V> map,
4504 +             Action<V> action) {
4505 +            if (action == null) throw new NullPointerException();
4506 +            return new ForEachValueTask<K,V>(map, null, -1, action);
4507 +        }
4508 +
4509 +        /**
4510 +         * Returns a task that when invoked, performs the given action
4511 +         * for each non-null transformation of each value.
4512 +         *
4513 +         * @param map the map
4514 +         * @param transformer a function returning the transformation
4515 +         * for an element, or null if there is no transformation (in
4516 +         * which case the action is not applied)
4517 +         * @param action the action
4518 +         */
4519 +        public static <K,V,U> ForkJoinTask<Void> forEachValue
4520 +            (ConcurrentHashMapV8<K,V> map,
4521 +             Fun<? super V, ? extends U> transformer,
4522 +             Action<U> action) {
4523 +            if (transformer == null || action == null)
4524 +                throw new NullPointerException();
4525 +            return new ForEachTransformedValueTask<K,V,U>
4526 +                (map, null, -1, transformer, action);
4527 +        }
4528 +
4529 +        /**
4530 +         * Returns a task that when invoked, returns a non-null result
4531 +         * from applying the given search function on each value, or
4532 +         * null if none.  Upon success, further element processing is
4533 +         * suppressed and the results of any other parallel
4534 +         * invocations of the search function are ignored.
4535 +         *
4536 +         * @param map the map
4537 +         * @param searchFunction a function returning a non-null
4538 +         * result on success, else null
4539 +         * @return the task
4540 +         */
4541 +        public static <K,V,U> ForkJoinTask<U> searchValues
4542 +            (ConcurrentHashMapV8<K,V> map,
4543 +             Fun<? super V, ? extends U> searchFunction) {
4544 +            if (searchFunction == null) throw new NullPointerException();
4545 +            return new SearchValuesTask<K,V,U>
4546 +                (map, null, -1, searchFunction,
4547 +                 new AtomicReference<U>());
4548 +        }
4549 +
4550 +        /**
4551 +         * Returns a task that when invoked, returns the result of
4552 +         * accumulating all values using the given reducer to combine
4553 +         * values, or null if none.
4554 +         *
4555 +         * @param map the map
4556 +         * @param reducer a commutative associative combining function
4557 +         * @return the task
4558 +         */
4559 +        public static <K,V> ForkJoinTask<V> reduceValues
4560 +            (ConcurrentHashMapV8<K,V> map,
4561 +             BiFun<? super V, ? super V, ? extends V> reducer) {
4562 +            if (reducer == null) throw new NullPointerException();
4563 +            return new ReduceValuesTask<K,V>
4564 +                (map, null, -1, null, reducer);
4565 +        }
4566 +
4567 +        /**
4568 +         * Returns a task that when invoked, returns the result of
4569 +         * accumulating the given transformation of all values using the
4570 +         * given reducer to combine values, or null if none.
4571 +         *
4572 +         * @param map the map
4573 +         * @param transformer a function returning the transformation
4574 +         * for an element, or null if there is no transformation (in
4575 +         * which case it is not combined).
4576 +         * @param reducer a commutative associative combining function
4577 +         * @return the task
4578 +         */
4579 +        public static <K,V,U> ForkJoinTask<U> reduceValues
4580 +            (ConcurrentHashMapV8<K,V> map,
4581 +             Fun<? super V, ? extends U> transformer,
4582 +             BiFun<? super U, ? super U, ? extends U> reducer) {
4583 +            if (transformer == null || reducer == null)
4584 +                throw new NullPointerException();
4585 +            return new MapReduceValuesTask<K,V,U>
4586 +                (map, null, -1, null, transformer, reducer);
4587 +        }
4588 +
4589 +        /**
4590 +         * Returns a task that when invoked, returns the result of
4591 +         * accumulating the given transformation of all values using the
4592 +         * given reducer to combine values, and the given basis as an
4593 +         * identity value.
4594 +         *
4595 +         * @param map the map
4596 +         * @param transformer a function returning the transformation
4597 +         * for an element
4598 +         * @param basis the identity (initial default value) for the reduction
4599 +         * @param reducer a commutative associative combining function
4600 +         * @return the task
4601 +         */
4602 +        public static <K,V> ForkJoinTask<Double> reduceValuesToDouble
4603 +            (ConcurrentHashMapV8<K,V> map,
4604 +             ObjectToDouble<? super V> transformer,
4605 +             double basis,
4606 +             DoubleByDoubleToDouble reducer) {
4607 +            if (transformer == null || reducer == null)
4608 +                throw new NullPointerException();
4609 +            return new MapReduceValuesToDoubleTask<K,V>
4610 +                (map, null, -1, null, transformer, basis, reducer);
4611 +        }
4612 +
4613 +        /**
4614 +         * Returns a task that when invoked, returns the result of
4615 +         * accumulating the given transformation of all values using the
4616 +         * given reducer to combine values, and the given basis as an
4617 +         * identity value.
4618 +         *
4619 +         * @param map the map
4620 +         * @param transformer a function returning the transformation
4621 +         * for an element
4622 +         * @param basis the identity (initial default value) for the reduction
4623 +         * @param reducer a commutative associative combining function
4624 +         * @return the task
4625 +         */
4626 +        public static <K,V> ForkJoinTask<Long> reduceValuesToLong
4627 +            (ConcurrentHashMapV8<K,V> map,
4628 +             ObjectToLong<? super V> transformer,
4629 +             long basis,
4630 +             LongByLongToLong reducer) {
4631 +            if (transformer == null || reducer == null)
4632 +                throw new NullPointerException();
4633 +            return new MapReduceValuesToLongTask<K,V>
4634 +                (map, null, -1, null, transformer, basis, reducer);
4635 +        }
4636 +
4637 +        /**
4638 +         * Returns a task that when invoked, returns the result of
4639 +         * accumulating the given transformation of all values using the
4640 +         * given reducer to combine values, and the given basis as an
4641 +         * identity value.
4642 +         *
4643 +         * @param map the map
4644 +         * @param transformer a function returning the transformation
4645 +         * for an element
4646 +         * @param basis the identity (initial default value) for the reduction
4647 +         * @param reducer a commutative associative combining function
4648 +         * @return the task
4649 +         */
4650 +        public static <K,V> ForkJoinTask<Integer> reduceValuesToInt
4651 +            (ConcurrentHashMapV8<K,V> map,
4652 +             ObjectToInt<? super V> transformer,
4653 +             int basis,
4654 +             IntByIntToInt reducer) {
4655 +            if (transformer == null || reducer == null)
4656 +                throw new NullPointerException();
4657 +            return new MapReduceValuesToIntTask<K,V>
4658 +                (map, null, -1, null, transformer, basis, reducer);
4659 +        }
4660 +
4661 +        /**
4662 +         * Returns a task that when invoked, perform the given action
4663 +         * for each entry.
4664 +         *
4665 +         * @param map the map
4666 +         * @param action the action
4667 +         */
4668 +        public static <K,V> ForkJoinTask<Void> forEachEntry
4669 +            (ConcurrentHashMapV8<K,V> map,
4670 +             Action<Map.Entry<K,V>> action) {
4671 +            if (action == null) throw new NullPointerException();
4672 +            return new ForEachEntryTask<K,V>(map, null, -1, action);
4673 +        }
4674 +
4675 +        /**
4676 +         * Returns a task that when invoked, perform the given action
4677 +         * for each non-null transformation of each entry.
4678 +         *
4679 +         * @param map the map
4680 +         * @param transformer a function returning the transformation
4681 +         * for an element, or null if there is no transformation (in
4682 +         * which case the action is not applied)
4683 +         * @param action the action
4684 +         */
4685 +        public static <K,V,U> ForkJoinTask<Void> forEachEntry
4686 +            (ConcurrentHashMapV8<K,V> map,
4687 +             Fun<Map.Entry<K,V>, ? extends U> transformer,
4688 +             Action<U> action) {
4689 +            if (transformer == null || action == null)
4690 +                throw new NullPointerException();
4691 +            return new ForEachTransformedEntryTask<K,V,U>
4692 +                (map, null, -1, transformer, action);
4693 +        }
4694 +
4695 +        /**
4696 +         * Returns a task that when invoked, returns a non-null result
4697 +         * from applying the given search function on each entry, or
4698 +         * null if none.  Upon success, further element processing is
4699 +         * suppressed and the results of any other parallel
4700 +         * invocations of the search function are ignored.
4701 +         *
4702 +         * @param map the map
4703 +         * @param searchFunction a function returning a non-null
4704 +         * result on success, else null
4705 +         * @return the task
4706 +         */
4707 +        public static <K,V,U> ForkJoinTask<U> searchEntries
4708 +            (ConcurrentHashMapV8<K,V> map,
4709 +             Fun<Map.Entry<K,V>, ? extends U> searchFunction) {
4710 +            if (searchFunction == null) throw new NullPointerException();
4711 +            return new SearchEntriesTask<K,V,U>
4712 +                (map, null, -1, searchFunction,
4713 +                 new AtomicReference<U>());
4714 +        }
4715 +
4716 +        /**
4717 +         * Returns a task that when invoked, returns the result of
4718 +         * accumulating all entries using the given reducer to combine
4719 +         * values, or null if none.
4720 +         *
4721 +         * @param map the map
4722 +         * @param reducer a commutative associative combining function
4723 +         * @return the task
4724 +         */
4725 +        public static <K,V> ForkJoinTask<Map.Entry<K,V>> reduceEntries
4726 +            (ConcurrentHashMapV8<K,V> map,
4727 +             BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4728 +            if (reducer == null) throw new NullPointerException();
4729 +            return new ReduceEntriesTask<K,V>
4730 +                (map, null, -1, null, reducer);
4731 +        }
4732 +
4733 +        /**
4734 +         * Returns a task that when invoked, returns the result of
4735 +         * accumulating the given transformation of all entries using the
4736 +         * given reducer to combine values, or null if none.
4737 +         *
4738 +         * @param map the map
4739 +         * @param transformer a function returning the transformation
4740 +         * for an element, or null if there is no transformation (in
4741 +         * which case it is not combined).
4742 +         * @param reducer a commutative associative combining function
4743 +         * @return the task
4744 +         */
4745 +        public static <K,V,U> ForkJoinTask<U> reduceEntries
4746 +            (ConcurrentHashMapV8<K,V> map,
4747 +             Fun<Map.Entry<K,V>, ? extends U> transformer,
4748 +             BiFun<? super U, ? super U, ? extends U> reducer) {
4749 +            if (transformer == null || reducer == null)
4750 +                throw new NullPointerException();
4751 +            return new MapReduceEntriesTask<K,V,U>
4752 +                (map, null, -1, null, transformer, reducer);
4753 +        }
4754 +
4755 +        /**
4756 +         * Returns a task that when invoked, returns the result of
4757 +         * accumulating the given transformation of all entries using the
4758 +         * given reducer to combine values, and the given basis as an
4759 +         * identity value.
4760 +         *
4761 +         * @param map the map
4762 +         * @param transformer a function returning the transformation
4763 +         * for an element
4764 +         * @param basis the identity (initial default value) for the reduction
4765 +         * @param reducer a commutative associative combining function
4766 +         * @return the task
4767 +         */
4768 +        public static <K,V> ForkJoinTask<Double> reduceEntriesToDouble
4769 +            (ConcurrentHashMapV8<K,V> map,
4770 +             ObjectToDouble<Map.Entry<K,V>> transformer,
4771 +             double basis,
4772 +             DoubleByDoubleToDouble reducer) {
4773 +            if (transformer == null || reducer == null)
4774 +                throw new NullPointerException();
4775 +            return new MapReduceEntriesToDoubleTask<K,V>
4776 +                (map, null, -1, null, transformer, basis, reducer);
4777 +        }
4778 +
4779 +        /**
4780 +         * Returns a task that when invoked, returns the result of
4781 +         * accumulating the given transformation of all entries using the
4782 +         * given reducer to combine values, and the given basis as an
4783 +         * identity value.
4784 +         *
4785 +         * @param map the map
4786 +         * @param transformer a function returning the transformation
4787 +         * for an element
4788 +         * @param basis the identity (initial default value) for the reduction
4789 +         * @param reducer a commutative associative combining function
4790 +         * @return the task
4791 +         */
4792 +        public static <K,V> ForkJoinTask<Long> reduceEntriesToLong
4793 +            (ConcurrentHashMapV8<K,V> map,
4794 +             ObjectToLong<Map.Entry<K,V>> transformer,
4795 +             long basis,
4796 +             LongByLongToLong reducer) {
4797 +            if (transformer == null || reducer == null)
4798 +                throw new NullPointerException();
4799 +            return new MapReduceEntriesToLongTask<K,V>
4800 +                (map, null, -1, null, transformer, basis, reducer);
4801 +        }
4802 +
4803 +        /**
4804 +         * Returns a task that when invoked, returns the result of
4805 +         * accumulating the given transformation of all entries using the
4806 +         * given reducer to combine values, and the given basis as an
4807 +         * identity value.
4808 +         *
4809 +         * @param map the map
4810 +         * @param transformer a function returning the transformation
4811 +         * for an element
4812 +         * @param basis the identity (initial default value) for the reduction
4813 +         * @param reducer a commutative associative combining function
4814 +         * @return the task
4815 +         */
4816 +        public static <K,V> ForkJoinTask<Integer> reduceEntriesToInt
4817 +            (ConcurrentHashMapV8<K,V> map,
4818 +             ObjectToInt<Map.Entry<K,V>> transformer,
4819 +             int basis,
4820 +             IntByIntToInt reducer) {
4821 +            if (transformer == null || reducer == null)
4822 +                throw new NullPointerException();
4823 +            return new MapReduceEntriesToIntTask<K,V>
4824 +                (map, null, -1, null, transformer, basis, reducer);
4825 +        }
4826 +    }
4827 +
4828 +    // -------------------------------------------------------
4829 +
4830 +    /**
4831 +     * Base for FJ tasks for bulk operations. This adds a variant of
4832 +     * CountedCompleters and some split and merge bookkeeping to
4833 +     * iterator functionality. The forEach and reduce methods are
4834 +     * similar to those illustrated in CountedCompleter documentation,
4835 +     * except that bottom-up reduction completions perform them within
4836 +     * their compute methods. The search methods are like forEach
4837 +     * except they continually poll for success and exit early.  Also,
4838 +     * exceptions are handled in a simpler manner, by just trying to
4839 +     * complete root task exceptionally.
4840 +     */
4841 +    @SuppressWarnings("serial") static abstract class BulkTask<K,V,R> extends Traverser<K,V,R> {
4842 +        final BulkTask<K,V,?> parent;  // completion target
4843 +        int batch;                     // split control; -1 for unknown
4844 +        int pending;                   // completion control
4845 +
4846 +        BulkTask(ConcurrentHashMapV8<K,V> map, BulkTask<K,V,?> parent,
4847 +                 int batch) {
4848 +            super(map);
4849 +            this.parent = parent;
4850 +            this.batch = batch;
4851 +            if (parent != null && map != null) { // split parent
4852 +                Node[] t;
4853 +                if ((t = parent.tab) == null &&
4854 +                    (t = parent.tab = map.table) != null)
4855 +                    parent.baseLimit = parent.baseSize = t.length;
4856 +                this.tab = t;
4857 +                this.baseSize = parent.baseSize;
4858 +                int hi = this.baseLimit = parent.baseLimit;
4859 +                parent.baseLimit = this.index = this.baseIndex =
4860 +                    (hi + parent.baseIndex + 1) >>> 1;
4861 +            }
4862 +        }
4863 +
4864 +        // FJ methods
4865 +
4866 +        /**
4867 +         * Propagates completion. Note that all reduce actions
4868 +         * bypass this method to combine while completing.
4869 +         */
4870 +        final void tryComplete() {
4871 +            BulkTask<K,V,?> a = this, s = a;
4872 +            for (int c;;) {
4873 +                if ((c = a.pending) == 0) {
4874 +                    if ((a = (s = a).parent) == null) {
4875 +                        s.quietlyComplete();
4876 +                        break;
4877 +                    }
4878 +                }
4879 +                else if (U.compareAndSwapInt(a, PENDING, c, c - 1))
4880 +                    break;
4881 +            }
4882 +        }
4883 +
4884 +        /**
4885 +         * Forces root task to complete.
4886 +         * @param ex if null, complete normally, else exceptionally
4887 +         * @return false to simplify use
4888 +         */
4889 +        final boolean tryCompleteComputation(Throwable ex) {
4890 +            for (BulkTask<K,V,?> a = this;;) {
4891 +                BulkTask<K,V,?> p = a.parent;
4892 +                if (p == null) {
4893 +                    if (ex != null)
4894 +                        a.completeExceptionally(ex);
4895 +                    else
4896 +                        a.quietlyComplete();
4897 +                    return false;
4898 +                }
4899 +                a = p;
4900 +            }
4901 +        }
4902 +
4903 +        /**
4904 +         * Version of tryCompleteComputation for function screening checks
4905 +         */
4906 +        final boolean abortOnNullFunction() {
4907 +            return tryCompleteComputation(new Error("Unexpected null function"));
4908 +        }
4909 +
4910 +        // utilities
4911 +
4912 +        /** CompareAndSet pending count */
4913 +        final boolean casPending(int cmp, int val) {
4914 +            return U.compareAndSwapInt(this, PENDING, cmp, val);
4915 +        }
4916 +
4917 +        /**
4918 +         * Returns approx exp2 of the number of times (minus one) to
4919 +         * split task by two before executing leaf action. This value
4920 +         * is faster to compute and more convenient to use as a guide
4921 +         * to splitting than is the depth, since it is used while
4922 +         * dividing by two anyway.
4923 +         */
4924 +        final int batch() {
4925 +            ConcurrentHashMapV8<K, V> m; int b; Node[] t;
4926 +            if ((b = batch) < 0 && (m = map) != null) { // force initialization
4927 +                if ((t = tab) == null && (t = tab = m.table) != null)
4928 +                    baseLimit = baseSize = t.length;
4929 +                if (t != null) {
4930 +                    long n = m.counter.sum();
4931 +                    int sp = getPool().getParallelism() << 3; // slack of 8
4932 +                    b = batch = (n <= 0L) ? 0 : (n < (long)sp) ? (int)n : sp;
4933 +                }
4934 +            }
4935 +            return b;
4936 +        }
4937 +
4938 +        /**
4939 +         * Returns exportable snapshot entry.
4940 +         */
4941 +        static <K,V> AbstractMap.SimpleEntry<K,V> entryFor(K k, V v) {
4942 +            return new AbstractMap.SimpleEntry<K,V>(k, v);
4943 +        }
4944 +
4945 +        // Unsafe mechanics
4946 +        private static final sun.misc.Unsafe U;
4947 +        private static final long PENDING;
4948 +        static {
4949 +            try {
4950 +                U = getUnsafe();
4951 +                PENDING = U.objectFieldOffset
4952 +                    (BulkTask.class.getDeclaredField("pending"));
4953 +            } catch (Exception e) {
4954 +                throw new Error(e);
4955 +            }
4956 +        }
4957 +    }
4958 +
4959 +    /*
4960 +     * Task classes. Coded in a regular but ugly format/style to
4961 +     * simplify checks that each variant differs in the right way from
4962 +     * others.
4963 +     */
4964 +
4965 +    @SuppressWarnings("serial") static final class ForEachKeyTask<K,V>
4966 +        extends BulkTask<K,V,Void> {
4967 +        final Action<K> action;
4968 +        ForEachKeyTask
4969 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
4970 +             Action<K> action) {
4971 +            super(m, p, b);
4972 +            this.action = action;
4973 +        }
4974 +        @SuppressWarnings("unchecked") public final boolean exec() {
4975 +            final Action<K> action = this.action;
4976 +            if (action == null)
4977 +                return abortOnNullFunction();
4978 +            try {
4979 +                int b = batch(), c;
4980 +                while (b > 1 && baseIndex != baseLimit) {
4981 +                    do {} while (!casPending(c = pending, c+1));
4982 +                    new ForEachKeyTask<K,V>(map, this, b >>>= 1, action).fork();
4983 +                }
4984 +                while (advance() != null)
4985 +                    action.apply((K)nextKey);
4986 +                tryComplete();
4987 +            } catch (Throwable ex) {
4988 +                return tryCompleteComputation(ex);
4989 +            }
4990 +            return false;
4991 +        }
4992 +    }
4993 +
4994 +    @SuppressWarnings("serial") static final class ForEachValueTask<K,V>
4995 +        extends BulkTask<K,V,Void> {
4996 +        final Action<V> action;
4997 +        ForEachValueTask
4998 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
4999 +             Action<V> action) {
5000 +            super(m, p, b);
5001 +            this.action = action;
5002 +        }
5003 +        @SuppressWarnings("unchecked") public final boolean exec() {
5004 +            final Action<V> action = this.action;
5005 +            if (action == null)
5006 +                return abortOnNullFunction();
5007 +            try {
5008 +                int b = batch(), c;
5009 +                while (b > 1 && baseIndex != baseLimit) {
5010 +                    do {} while (!casPending(c = pending, c+1));
5011 +                    new ForEachValueTask<K,V>(map, this, b >>>= 1, action).fork();
5012 +                }
5013 +                Object v;
5014 +                while ((v = advance()) != null)
5015 +                    action.apply((V)v);
5016 +                tryComplete();
5017 +            } catch (Throwable ex) {
5018 +                return tryCompleteComputation(ex);
5019 +            }
5020 +            return false;
5021 +        }
5022 +    }
5023 +
5024 +    @SuppressWarnings("serial") static final class ForEachEntryTask<K,V>
5025 +        extends BulkTask<K,V,Void> {
5026 +        final Action<Entry<K,V>> action;
5027 +        ForEachEntryTask
5028 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5029 +             Action<Entry<K,V>> action) {
5030 +            super(m, p, b);
5031 +            this.action = action;
5032 +        }
5033 +        @SuppressWarnings("unchecked") public final boolean exec() {
5034 +            final Action<Entry<K,V>> action = this.action;
5035 +            if (action == null)
5036 +                return abortOnNullFunction();
5037 +            try {
5038 +                int b = batch(), c;
5039 +                while (b > 1 && baseIndex != baseLimit) {
5040 +                    do {} while (!casPending(c = pending, c+1));
5041 +                    new ForEachEntryTask<K,V>(map, this, b >>>= 1, action).fork();
5042 +                }
5043 +                Object v;
5044 +                while ((v = advance()) != null)
5045 +                    action.apply(entryFor((K)nextKey, (V)v));
5046 +                tryComplete();
5047 +            } catch (Throwable ex) {
5048 +                return tryCompleteComputation(ex);
5049 +            }
5050 +            return false;
5051 +        }
5052 +    }
5053 +
5054 +    @SuppressWarnings("serial") static final class ForEachMappingTask<K,V>
5055 +        extends BulkTask<K,V,Void> {
5056 +        final BiAction<K,V> action;
5057 +        ForEachMappingTask
5058 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5059 +             BiAction<K,V> action) {
5060 +            super(m, p, b);
5061 +            this.action = action;
5062 +        }
5063 +        @SuppressWarnings("unchecked") public final boolean exec() {
5064 +            final BiAction<K,V> action = this.action;
5065 +            if (action == null)
5066 +                return abortOnNullFunction();
5067 +            try {
5068 +                int b = batch(), c;
5069 +                while (b > 1 && baseIndex != baseLimit) {
5070 +                    do {} while (!casPending(c = pending, c+1));
5071 +                    new ForEachMappingTask<K,V>(map, this, b >>>= 1,
5072 +                                                action).fork();
5073 +                }
5074 +                Object v;
5075 +                while ((v = advance()) != null)
5076 +                    action.apply((K)nextKey, (V)v);
5077 +                tryComplete();
5078 +            } catch (Throwable ex) {
5079 +                return tryCompleteComputation(ex);
5080 +            }
5081 +            return false;
5082 +        }
5083 +    }
5084 +
5085 +    @SuppressWarnings("serial") static final class ForEachTransformedKeyTask<K,V,U>
5086 +        extends BulkTask<K,V,Void> {
5087 +        final Fun<? super K, ? extends U> transformer;
5088 +        final Action<U> action;
5089 +        ForEachTransformedKeyTask
5090 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5091 +             Fun<? super K, ? extends U> transformer,
5092 +             Action<U> action) {
5093 +            super(m, p, b);
5094 +            this.transformer = transformer;
5095 +            this.action = action;
5096 +
5097 +        }
5098 +        @SuppressWarnings("unchecked") public final boolean exec() {
5099 +            final Fun<? super K, ? extends U> transformer =
5100 +                this.transformer;
5101 +            final Action<U> action = this.action;
5102 +            if (transformer == null || action == null)
5103 +                return abortOnNullFunction();
5104 +            try {
5105 +                int b = batch(), c;
5106 +                while (b > 1 && baseIndex != baseLimit) {
5107 +                    do {} while (!casPending(c = pending, c+1));
5108 +                    new ForEachTransformedKeyTask<K,V,U>
5109 +                        (map, this, b >>>= 1, transformer, action).fork();
5110 +                }
5111 +                U u;
5112 +                while (advance() != null) {
5113 +                    if ((u = transformer.apply((K)nextKey)) != null)
5114 +                        action.apply(u);
5115 +                }
5116 +                tryComplete();
5117 +            } catch (Throwable ex) {
5118 +                return tryCompleteComputation(ex);
5119 +            }
5120 +            return false;
5121 +        }
5122 +    }
5123 +
5124 +    @SuppressWarnings("serial") static final class ForEachTransformedValueTask<K,V,U>
5125 +        extends BulkTask<K,V,Void> {
5126 +        final Fun<? super V, ? extends U> transformer;
5127 +        final Action<U> action;
5128 +        ForEachTransformedValueTask
5129 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5130 +             Fun<? super V, ? extends U> transformer,
5131 +             Action<U> action) {
5132 +            super(m, p, b);
5133 +            this.transformer = transformer;
5134 +            this.action = action;
5135 +
5136 +        }
5137 +        @SuppressWarnings("unchecked") public final boolean exec() {
5138 +            final Fun<? super V, ? extends U> transformer =
5139 +                this.transformer;
5140 +            final Action<U> action = this.action;
5141 +            if (transformer == null || action == null)
5142 +                return abortOnNullFunction();
5143 +            try {
5144 +                int b = batch(), c;
5145 +                while (b > 1 && baseIndex != baseLimit) {
5146 +                    do {} while (!casPending(c = pending, c+1));
5147 +                    new ForEachTransformedValueTask<K,V,U>
5148 +                        (map, this, b >>>= 1, transformer, action).fork();
5149 +                }
5150 +                Object v; U u;
5151 +                while ((v = advance()) != null) {
5152 +                    if ((u = transformer.apply((V)v)) != null)
5153 +                        action.apply(u);
5154 +                }
5155 +                tryComplete();
5156 +            } catch (Throwable ex) {
5157 +                return tryCompleteComputation(ex);
5158 +            }
5159 +            return false;
5160 +        }
5161 +    }
5162 +
5163 +    @SuppressWarnings("serial") static final class ForEachTransformedEntryTask<K,V,U>
5164 +        extends BulkTask<K,V,Void> {
5165 +        final Fun<Map.Entry<K,V>, ? extends U> transformer;
5166 +        final Action<U> action;
5167 +        ForEachTransformedEntryTask
5168 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5169 +             Fun<Map.Entry<K,V>, ? extends U> transformer,
5170 +             Action<U> action) {
5171 +            super(m, p, b);
5172 +            this.transformer = transformer;
5173 +            this.action = action;
5174 +
5175 +        }
5176 +        @SuppressWarnings("unchecked") public final boolean exec() {
5177 +            final Fun<Map.Entry<K,V>, ? extends U> transformer =
5178 +                this.transformer;
5179 +            final Action<U> action = this.action;
5180 +            if (transformer == null || action == null)
5181 +                return abortOnNullFunction();
5182 +            try {
5183 +                int b = batch(), c;
5184 +                while (b > 1 && baseIndex != baseLimit) {
5185 +                    do {} while (!casPending(c = pending, c+1));
5186 +                    new ForEachTransformedEntryTask<K,V,U>
5187 +                        (map, this, b >>>= 1, transformer, action).fork();
5188 +                }
5189 +                Object v; U u;
5190 +                while ((v = advance()) != null) {
5191 +                    if ((u = transformer.apply(entryFor((K)nextKey, (V)v))) != null)
5192 +                        action.apply(u);
5193 +                }
5194 +                tryComplete();
5195 +            } catch (Throwable ex) {
5196 +                return tryCompleteComputation(ex);
5197 +            }
5198 +            return false;
5199 +        }
5200 +    }
5201 +
5202 +    @SuppressWarnings("serial") static final class ForEachTransformedMappingTask<K,V,U>
5203 +        extends BulkTask<K,V,Void> {
5204 +        final BiFun<? super K, ? super V, ? extends U> transformer;
5205 +        final Action<U> action;
5206 +        ForEachTransformedMappingTask
5207 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5208 +             BiFun<? super K, ? super V, ? extends U> transformer,
5209 +             Action<U> action) {
5210 +            super(m, p, b);
5211 +            this.transformer = transformer;
5212 +            this.action = action;
5213 +
5214 +        }
5215 +        @SuppressWarnings("unchecked") public final boolean exec() {
5216 +            final BiFun<? super K, ? super V, ? extends U> transformer =
5217 +                this.transformer;
5218 +            final Action<U> action = this.action;
5219 +            if (transformer == null || action == null)
5220 +                return abortOnNullFunction();
5221 +            try {
5222 +                int b = batch(), c;
5223 +                while (b > 1 && baseIndex != baseLimit) {
5224 +                    do {} while (!casPending(c = pending, c+1));
5225 +                    new ForEachTransformedMappingTask<K,V,U>
5226 +                        (map, this, b >>>= 1, transformer, action).fork();
5227 +                }
5228 +                Object v; U u;
5229 +                while ((v = advance()) != null) {
5230 +                    if ((u = transformer.apply((K)nextKey, (V)v)) != null)
5231 +                        action.apply(u);
5232 +                }
5233 +                tryComplete();
5234 +            } catch (Throwable ex) {
5235 +                return tryCompleteComputation(ex);
5236 +            }
5237 +            return false;
5238 +        }
5239 +    }
5240 +
5241 +    @SuppressWarnings("serial") static final class SearchKeysTask<K,V,U>
5242 +        extends BulkTask<K,V,U> {
5243 +        final Fun<? super K, ? extends U> searchFunction;
5244 +        final AtomicReference<U> result;
5245 +        SearchKeysTask
5246 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5247 +             Fun<? super K, ? extends U> searchFunction,
5248 +             AtomicReference<U> result) {
5249 +            super(m, p, b);
5250 +            this.searchFunction = searchFunction; this.result = result;
5251 +        }
5252 +        @SuppressWarnings("unchecked") public final boolean exec() {
5253 +            AtomicReference<U> result = this.result;
5254 +            final Fun<? super K, ? extends U> searchFunction =
5255 +                this.searchFunction;
5256 +            if (searchFunction == null || result == null)
5257 +                return abortOnNullFunction();
5258 +            try {
5259 +                int b = batch(), c;
5260 +                while (b > 1 && baseIndex != baseLimit && result.get() == null) {
5261 +                    do {} while (!casPending(c = pending, c+1));
5262 +                    new SearchKeysTask<K,V,U>(map, this, b >>>= 1,
5263 +                                              searchFunction, result).fork();
5264 +                }
5265 +                U u;
5266 +                while (result.get() == null && advance() != null) {
5267 +                    if ((u = searchFunction.apply((K)nextKey)) != null) {
5268 +                        if (result.compareAndSet(null, u))
5269 +                            tryCompleteComputation(null);
5270 +                        break;
5271 +                    }
5272 +                }
5273 +                tryComplete();
5274 +            } catch (Throwable ex) {
5275 +                return tryCompleteComputation(ex);
5276 +            }
5277 +            return false;
5278 +        }
5279 +        public final U getRawResult() { return result.get(); }
5280 +    }
5281 +
5282 +    @SuppressWarnings("serial") static final class SearchValuesTask<K,V,U>
5283 +        extends BulkTask<K,V,U> {
5284 +        final Fun<? super V, ? extends U> searchFunction;
5285 +        final AtomicReference<U> result;
5286 +        SearchValuesTask
5287 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5288 +             Fun<? super V, ? extends U> searchFunction,
5289 +             AtomicReference<U> result) {
5290 +            super(m, p, b);
5291 +            this.searchFunction = searchFunction; this.result = result;
5292 +        }
5293 +        @SuppressWarnings("unchecked") public final boolean exec() {
5294 +            AtomicReference<U> result = this.result;
5295 +            final Fun<? super V, ? extends U> searchFunction =
5296 +                this.searchFunction;
5297 +            if (searchFunction == null || result == null)
5298 +                return abortOnNullFunction();
5299 +            try {
5300 +                int b = batch(), c;
5301 +                while (b > 1 && baseIndex != baseLimit && result.get() == null) {
5302 +                    do {} while (!casPending(c = pending, c+1));
5303 +                    new SearchValuesTask<K,V,U>(map, this, b >>>= 1,
5304 +                                                searchFunction, result).fork();
5305 +                }
5306 +                Object v; U u;
5307 +                while (result.get() == null && (v = advance()) != null) {
5308 +                    if ((u = searchFunction.apply((V)v)) != null) {
5309 +                        if (result.compareAndSet(null, u))
5310 +                            tryCompleteComputation(null);
5311 +                        break;
5312 +                    }
5313 +                }
5314 +                tryComplete();
5315 +            } catch (Throwable ex) {
5316 +                return tryCompleteComputation(ex);
5317 +            }
5318 +            return false;
5319 +        }
5320 +        public final U getRawResult() { return result.get(); }
5321 +    }
5322 +
5323 +    @SuppressWarnings("serial") static final class SearchEntriesTask<K,V,U>
5324 +        extends BulkTask<K,V,U> {
5325 +        final Fun<Entry<K,V>, ? extends U> searchFunction;
5326 +        final AtomicReference<U> result;
5327 +        SearchEntriesTask
5328 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5329 +             Fun<Entry<K,V>, ? extends U> searchFunction,
5330 +             AtomicReference<U> result) {
5331 +            super(m, p, b);
5332 +            this.searchFunction = searchFunction; this.result = result;
5333 +        }
5334 +        @SuppressWarnings("unchecked") public final boolean exec() {
5335 +            AtomicReference<U> result = this.result;
5336 +            final Fun<Entry<K,V>, ? extends U> searchFunction =
5337 +                this.searchFunction;
5338 +            if (searchFunction == null || result == null)
5339 +                return abortOnNullFunction();
5340 +            try {
5341 +                int b = batch(), c;
5342 +                while (b > 1 && baseIndex != baseLimit && result.get() == null) {
5343 +                    do {} while (!casPending(c = pending, c+1));
5344 +                    new SearchEntriesTask<K,V,U>(map, this, b >>>= 1,
5345 +                                                 searchFunction, result).fork();
5346 +                }
5347 +                Object v; U u;
5348 +                while (result.get() == null && (v = advance()) != null) {
5349 +                    if ((u = searchFunction.apply(entryFor((K)nextKey, (V)v))) != null) {
5350 +                        if (result.compareAndSet(null, u))
5351 +                            tryCompleteComputation(null);
5352 +                        break;
5353 +                    }
5354 +                }
5355 +                tryComplete();
5356 +            } catch (Throwable ex) {
5357 +                return tryCompleteComputation(ex);
5358 +            }
5359 +            return false;
5360 +        }
5361 +        public final U getRawResult() { return result.get(); }
5362 +    }
5363 +
5364 +    @SuppressWarnings("serial") static final class SearchMappingsTask<K,V,U>
5365 +        extends BulkTask<K,V,U> {
5366 +        final BiFun<? super K, ? super V, ? extends U> searchFunction;
5367 +        final AtomicReference<U> result;
5368 +        SearchMappingsTask
5369 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5370 +             BiFun<? super K, ? super V, ? extends U> searchFunction,
5371 +             AtomicReference<U> result) {
5372 +            super(m, p, b);
5373 +            this.searchFunction = searchFunction; this.result = result;
5374 +        }
5375 +        @SuppressWarnings("unchecked") public final boolean exec() {
5376 +            AtomicReference<U> result = this.result;
5377 +            final BiFun<? super K, ? super V, ? extends U> searchFunction =
5378 +                this.searchFunction;
5379 +            if (searchFunction == null || result == null)
5380 +                return abortOnNullFunction();
5381 +            try {
5382 +                int b = batch(), c;
5383 +                while (b > 1 && baseIndex != baseLimit && result.get() == null) {
5384 +                    do {} while (!casPending(c = pending, c+1));
5385 +                    new SearchMappingsTask<K,V,U>(map, this, b >>>= 1,
5386 +                                                  searchFunction, result).fork();
5387 +                }
5388 +                Object v; U u;
5389 +                while (result.get() == null && (v = advance()) != null) {
5390 +                    if ((u = searchFunction.apply((K)nextKey, (V)v)) != null) {
5391 +                        if (result.compareAndSet(null, u))
5392 +                            tryCompleteComputation(null);
5393 +                        break;
5394 +                    }
5395 +                }
5396 +                tryComplete();
5397 +            } catch (Throwable ex) {
5398 +                return tryCompleteComputation(ex);
5399 +            }
5400 +            return false;
5401 +        }
5402 +        public final U getRawResult() { return result.get(); }
5403 +    }
5404 +
5405 +    @SuppressWarnings("serial") static final class ReduceKeysTask<K,V>
5406 +        extends BulkTask<K,V,K> {
5407 +        final BiFun<? super K, ? super K, ? extends K> reducer;
5408 +        K result;
5409 +        ReduceKeysTask<K,V> rights, nextRight;
5410 +        ReduceKeysTask
5411 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5412 +             ReduceKeysTask<K,V> nextRight,
5413 +             BiFun<? super K, ? super K, ? extends K> reducer) {
5414 +            super(m, p, b); this.nextRight = nextRight;
5415 +            this.reducer = reducer;
5416 +        }
5417 +        @SuppressWarnings("unchecked") public final boolean exec() {
5418 +            final BiFun<? super K, ? super K, ? extends K> reducer =
5419 +                this.reducer;
5420 +            if (reducer == null)
5421 +                return abortOnNullFunction();
5422 +            try {
5423 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5424 +                    do {} while (!casPending(c = pending, c+1));
5425 +                    (rights = new ReduceKeysTask<K,V>
5426 +                     (map, this, b >>>= 1, rights, reducer)).fork();
5427 +                }
5428 +                K r = null;
5429 +                while (advance() != null) {
5430 +                    K u = (K)nextKey;
5431 +                    r = (r == null) ? u : reducer.apply(r, u);
5432 +                }
5433 +                result = r;
5434 +                for (ReduceKeysTask<K,V> t = this, s;;) {
5435 +                    int c; BulkTask<K,V,?> par; K tr, sr;
5436 +                    if ((c = t.pending) == 0) {
5437 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5438 +                            if ((sr = s.result) != null)
5439 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5440 +                        }
5441 +                        if ((par = t.parent) == null ||
5442 +                            !(par instanceof ReduceKeysTask)) {
5443 +                            t.quietlyComplete();
5444 +                            break;
5445 +                        }
5446 +                        t = (ReduceKeysTask<K,V>)par;
5447 +                    }
5448 +                    else if (t.casPending(c, c - 1))
5449 +                        break;
5450 +                }
5451 +            } catch (Throwable ex) {
5452 +                return tryCompleteComputation(ex);
5453 +            }
5454 +            return false;
5455 +        }
5456 +        public final K getRawResult() { return result; }
5457 +    }
5458 +
5459 +    @SuppressWarnings("serial") static final class ReduceValuesTask<K,V>
5460 +        extends BulkTask<K,V,V> {
5461 +        final BiFun<? super V, ? super V, ? extends V> reducer;
5462 +        V result;
5463 +        ReduceValuesTask<K,V> rights, nextRight;
5464 +        ReduceValuesTask
5465 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5466 +             ReduceValuesTask<K,V> nextRight,
5467 +             BiFun<? super V, ? super V, ? extends V> reducer) {
5468 +            super(m, p, b); this.nextRight = nextRight;
5469 +            this.reducer = reducer;
5470 +        }
5471 +        @SuppressWarnings("unchecked") public final boolean exec() {
5472 +            final BiFun<? super V, ? super V, ? extends V> reducer =
5473 +                this.reducer;
5474 +            if (reducer == null)
5475 +                return abortOnNullFunction();
5476 +            try {
5477 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5478 +                    do {} while (!casPending(c = pending, c+1));
5479 +                    (rights = new ReduceValuesTask<K,V>
5480 +                     (map, this, b >>>= 1, rights, reducer)).fork();
5481 +                }
5482 +                V r = null;
5483 +                Object v;
5484 +                while ((v = advance()) != null) {
5485 +                    V u = (V)v;
5486 +                    r = (r == null) ? u : reducer.apply(r, u);
5487 +                }
5488 +                result = r;
5489 +                for (ReduceValuesTask<K,V> t = this, s;;) {
5490 +                    int c; BulkTask<K,V,?> par; V tr, sr;
5491 +                    if ((c = t.pending) == 0) {
5492 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5493 +                            if ((sr = s.result) != null)
5494 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5495 +                        }
5496 +                        if ((par = t.parent) == null ||
5497 +                            !(par instanceof ReduceValuesTask)) {
5498 +                            t.quietlyComplete();
5499 +                            break;
5500 +                        }
5501 +                        t = (ReduceValuesTask<K,V>)par;
5502 +                    }
5503 +                    else if (t.casPending(c, c - 1))
5504 +                        break;
5505 +                }
5506 +            } catch (Throwable ex) {
5507 +                return tryCompleteComputation(ex);
5508 +            }
5509 +            return false;
5510 +        }
5511 +        public final V getRawResult() { return result; }
5512 +    }
5513 +
5514 +    @SuppressWarnings("serial") static final class ReduceEntriesTask<K,V>
5515 +        extends BulkTask<K,V,Map.Entry<K,V>> {
5516 +        final BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5517 +        Map.Entry<K,V> result;
5518 +        ReduceEntriesTask<K,V> rights, nextRight;
5519 +        ReduceEntriesTask
5520 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5521 +             ReduceEntriesTask<K,V> nextRight,
5522 +             BiFun<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5523 +            super(m, p, b); this.nextRight = nextRight;
5524 +            this.reducer = reducer;
5525 +        }
5526 +        @SuppressWarnings("unchecked") public final boolean exec() {
5527 +            final BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer =
5528 +                this.reducer;
5529 +            if (reducer == null)
5530 +                return abortOnNullFunction();
5531 +            try {
5532 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5533 +                    do {} while (!casPending(c = pending, c+1));
5534 +                    (rights = new ReduceEntriesTask<K,V>
5535 +                     (map, this, b >>>= 1, rights, reducer)).fork();
5536 +                }
5537 +                Map.Entry<K,V> r = null;
5538 +                Object v;
5539 +                while ((v = advance()) != null) {
5540 +                    Map.Entry<K,V> u = entryFor((K)nextKey, (V)v);
5541 +                    r = (r == null) ? u : reducer.apply(r, u);
5542 +                }
5543 +                result = r;
5544 +                for (ReduceEntriesTask<K,V> t = this, s;;) {
5545 +                    int c; BulkTask<K,V,?> par; Map.Entry<K,V> tr, sr;
5546 +                    if ((c = t.pending) == 0) {
5547 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5548 +                            if ((sr = s.result) != null)
5549 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5550 +                        }
5551 +                        if ((par = t.parent) == null ||
5552 +                            !(par instanceof ReduceEntriesTask)) {
5553 +                            t.quietlyComplete();
5554 +                            break;
5555 +                        }
5556 +                        t = (ReduceEntriesTask<K,V>)par;
5557 +                    }
5558 +                    else if (t.casPending(c, c - 1))
5559 +                        break;
5560 +                }
5561 +            } catch (Throwable ex) {
5562 +                return tryCompleteComputation(ex);
5563 +            }
5564 +            return false;
5565 +        }
5566 +        public final Map.Entry<K,V> getRawResult() { return result; }
5567 +    }
5568 +
5569 +    @SuppressWarnings("serial") static final class MapReduceKeysTask<K,V,U>
5570 +        extends BulkTask<K,V,U> {
5571 +        final Fun<? super K, ? extends U> transformer;
5572 +        final BiFun<? super U, ? super U, ? extends U> reducer;
5573 +        U result;
5574 +        MapReduceKeysTask<K,V,U> rights, nextRight;
5575 +        MapReduceKeysTask
5576 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5577 +             MapReduceKeysTask<K,V,U> nextRight,
5578 +             Fun<? super K, ? extends U> transformer,
5579 +             BiFun<? super U, ? super U, ? extends U> reducer) {
5580 +            super(m, p, b); this.nextRight = nextRight;
5581 +            this.transformer = transformer;
5582 +            this.reducer = reducer;
5583 +        }
5584 +        @SuppressWarnings("unchecked") public final boolean exec() {
5585 +            final Fun<? super K, ? extends U> transformer =
5586 +                this.transformer;
5587 +            final BiFun<? super U, ? super U, ? extends U> reducer =
5588 +                this.reducer;
5589 +            if (transformer == null || reducer == null)
5590 +                return abortOnNullFunction();
5591 +            try {
5592 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5593 +                    do {} while (!casPending(c = pending, c+1));
5594 +                    (rights = new MapReduceKeysTask<K,V,U>
5595 +                     (map, this, b >>>= 1, rights, transformer, reducer)).fork();
5596 +                }
5597 +                U r = null, u;
5598 +                while (advance() != null) {
5599 +                    if ((u = transformer.apply((K)nextKey)) != null)
5600 +                        r = (r == null) ? u : reducer.apply(r, u);
5601 +                }
5602 +                result = r;
5603 +                for (MapReduceKeysTask<K,V,U> t = this, s;;) {
5604 +                    int c; BulkTask<K,V,?> par; U tr, sr;
5605 +                    if ((c = t.pending) == 0) {
5606 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5607 +                            if ((sr = s.result) != null)
5608 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5609 +                        }
5610 +                        if ((par = t.parent) == null ||
5611 +                            !(par instanceof MapReduceKeysTask)) {
5612 +                            t.quietlyComplete();
5613 +                            break;
5614 +                        }
5615 +                        t = (MapReduceKeysTask<K,V,U>)par;
5616 +                    }
5617 +                    else if (t.casPending(c, c - 1))
5618 +                        break;
5619 +                }
5620 +            } catch (Throwable ex) {
5621 +                return tryCompleteComputation(ex);
5622 +            }
5623 +            return false;
5624 +        }
5625 +        public final U getRawResult() { return result; }
5626 +    }
5627 +
5628 +    @SuppressWarnings("serial") static final class MapReduceValuesTask<K,V,U>
5629 +        extends BulkTask<K,V,U> {
5630 +        final Fun<? super V, ? extends U> transformer;
5631 +        final BiFun<? super U, ? super U, ? extends U> reducer;
5632 +        U result;
5633 +        MapReduceValuesTask<K,V,U> rights, nextRight;
5634 +        MapReduceValuesTask
5635 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5636 +             MapReduceValuesTask<K,V,U> nextRight,
5637 +             Fun<? super V, ? extends U> transformer,
5638 +             BiFun<? super U, ? super U, ? extends U> reducer) {
5639 +            super(m, p, b); this.nextRight = nextRight;
5640 +            this.transformer = transformer;
5641 +            this.reducer = reducer;
5642 +        }
5643 +        @SuppressWarnings("unchecked") public final boolean exec() {
5644 +            final Fun<? super V, ? extends U> transformer =
5645 +                this.transformer;
5646 +            final BiFun<? super U, ? super U, ? extends U> reducer =
5647 +                this.reducer;
5648 +            if (transformer == null || reducer == null)
5649 +                return abortOnNullFunction();
5650 +            try {
5651 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5652 +                    do {} while (!casPending(c = pending, c+1));
5653 +                    (rights = new MapReduceValuesTask<K,V,U>
5654 +                     (map, this, b >>>= 1, rights, transformer, reducer)).fork();
5655 +                }
5656 +                U r = null, u;
5657 +                Object v;
5658 +                while ((v = advance()) != null) {
5659 +                    if ((u = transformer.apply((V)v)) != null)
5660 +                        r = (r == null) ? u : reducer.apply(r, u);
5661 +                }
5662 +                result = r;
5663 +                for (MapReduceValuesTask<K,V,U> t = this, s;;) {
5664 +                    int c; BulkTask<K,V,?> par; U tr, sr;
5665 +                    if ((c = t.pending) == 0) {
5666 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5667 +                            if ((sr = s.result) != null)
5668 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5669 +                        }
5670 +                        if ((par = t.parent) == null ||
5671 +                            !(par instanceof MapReduceValuesTask)) {
5672 +                            t.quietlyComplete();
5673 +                            break;
5674 +                        }
5675 +                        t = (MapReduceValuesTask<K,V,U>)par;
5676 +                    }
5677 +                    else if (t.casPending(c, c - 1))
5678 +                        break;
5679 +                }
5680 +            } catch (Throwable ex) {
5681 +                return tryCompleteComputation(ex);
5682 +            }
5683 +            return false;
5684 +        }
5685 +        public final U getRawResult() { return result; }
5686 +    }
5687 +
5688 +    @SuppressWarnings("serial") static final class MapReduceEntriesTask<K,V,U>
5689 +        extends BulkTask<K,V,U> {
5690 +        final Fun<Map.Entry<K,V>, ? extends U> transformer;
5691 +        final BiFun<? super U, ? super U, ? extends U> reducer;
5692 +        U result;
5693 +        MapReduceEntriesTask<K,V,U> rights, nextRight;
5694 +        MapReduceEntriesTask
5695 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5696 +             MapReduceEntriesTask<K,V,U> nextRight,
5697 +             Fun<Map.Entry<K,V>, ? extends U> transformer,
5698 +             BiFun<? super U, ? super U, ? extends U> reducer) {
5699 +            super(m, p, b); this.nextRight = nextRight;
5700 +            this.transformer = transformer;
5701 +            this.reducer = reducer;
5702 +        }
5703 +        @SuppressWarnings("unchecked") public final boolean exec() {
5704 +            final Fun<Map.Entry<K,V>, ? extends U> transformer =
5705 +                this.transformer;
5706 +            final BiFun<? super U, ? super U, ? extends U> reducer =
5707 +                this.reducer;
5708 +            if (transformer == null || reducer == null)
5709 +                return abortOnNullFunction();
5710 +            try {
5711 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5712 +                    do {} while (!casPending(c = pending, c+1));
5713 +                    (rights = new MapReduceEntriesTask<K,V,U>
5714 +                     (map, this, b >>>= 1, rights, transformer, reducer)).fork();
5715 +                }
5716 +                U r = null, u;
5717 +                Object v;
5718 +                while ((v = advance()) != null) {
5719 +                    if ((u = transformer.apply(entryFor((K)nextKey, (V)v))) != null)
5720 +                        r = (r == null) ? u : reducer.apply(r, u);
5721 +                }
5722 +                result = r;
5723 +                for (MapReduceEntriesTask<K,V,U> t = this, s;;) {
5724 +                    int c; BulkTask<K,V,?> par; U tr, sr;
5725 +                    if ((c = t.pending) == 0) {
5726 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5727 +                            if ((sr = s.result) != null)
5728 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5729 +                        }
5730 +                        if ((par = t.parent) == null ||
5731 +                            !(par instanceof MapReduceEntriesTask)) {
5732 +                            t.quietlyComplete();
5733 +                            break;
5734 +                        }
5735 +                        t = (MapReduceEntriesTask<K,V,U>)par;
5736 +                    }
5737 +                    else if (t.casPending(c, c - 1))
5738 +                        break;
5739 +                }
5740 +            } catch (Throwable ex) {
5741 +                return tryCompleteComputation(ex);
5742 +            }
5743 +            return false;
5744 +        }
5745 +        public final U getRawResult() { return result; }
5746 +    }
5747 +
5748 +    @SuppressWarnings("serial") static final class MapReduceMappingsTask<K,V,U>
5749 +        extends BulkTask<K,V,U> {
5750 +        final BiFun<? super K, ? super V, ? extends U> transformer;
5751 +        final BiFun<? super U, ? super U, ? extends U> reducer;
5752 +        U result;
5753 +        MapReduceMappingsTask<K,V,U> rights, nextRight;
5754 +        MapReduceMappingsTask
5755 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5756 +             MapReduceMappingsTask<K,V,U> nextRight,
5757 +             BiFun<? super K, ? super V, ? extends U> transformer,
5758 +             BiFun<? super U, ? super U, ? extends U> reducer) {
5759 +            super(m, p, b); this.nextRight = nextRight;
5760 +            this.transformer = transformer;
5761 +            this.reducer = reducer;
5762 +        }
5763 +        @SuppressWarnings("unchecked") public final boolean exec() {
5764 +            final BiFun<? super K, ? super V, ? extends U> transformer =
5765 +                this.transformer;
5766 +            final BiFun<? super U, ? super U, ? extends U> reducer =
5767 +                this.reducer;
5768 +            if (transformer == null || reducer == null)
5769 +                return abortOnNullFunction();
5770 +            try {
5771 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5772 +                    do {} while (!casPending(c = pending, c+1));
5773 +                    (rights = new MapReduceMappingsTask<K,V,U>
5774 +                     (map, this, b >>>= 1, rights, transformer, reducer)).fork();
5775 +                }
5776 +                U r = null, u;
5777 +                Object v;
5778 +                while ((v = advance()) != null) {
5779 +                    if ((u = transformer.apply((K)nextKey, (V)v)) != null)
5780 +                        r = (r == null) ? u : reducer.apply(r, u);
5781 +                }
5782 +                result = r;
5783 +                for (MapReduceMappingsTask<K,V,U> t = this, s;;) {
5784 +                    int c; BulkTask<K,V,?> par; U tr, sr;
5785 +                    if ((c = t.pending) == 0) {
5786 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5787 +                            if ((sr = s.result) != null)
5788 +                                t.result = ((tr = t.result) == null) ? sr : reducer.apply(tr, sr);
5789 +                        }
5790 +                        if ((par = t.parent) == null ||
5791 +                            !(par instanceof MapReduceMappingsTask)) {
5792 +                            t.quietlyComplete();
5793 +                            break;
5794 +                        }
5795 +                        t = (MapReduceMappingsTask<K,V,U>)par;
5796 +                    }
5797 +                    else if (t.casPending(c, c - 1))
5798 +                        break;
5799 +                }
5800 +            } catch (Throwable ex) {
5801 +                return tryCompleteComputation(ex);
5802 +            }
5803 +            return false;
5804 +        }
5805 +        public final U getRawResult() { return result; }
5806 +    }
5807 +
5808 +    @SuppressWarnings("serial") static final class MapReduceKeysToDoubleTask<K,V>
5809 +        extends BulkTask<K,V,Double> {
5810 +        final ObjectToDouble<? super K> transformer;
5811 +        final DoubleByDoubleToDouble reducer;
5812 +        final double basis;
5813 +        double result;
5814 +        MapReduceKeysToDoubleTask<K,V> rights, nextRight;
5815 +        MapReduceKeysToDoubleTask
5816 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5817 +             MapReduceKeysToDoubleTask<K,V> nextRight,
5818 +             ObjectToDouble<? super K> transformer,
5819 +             double basis,
5820 +             DoubleByDoubleToDouble reducer) {
5821 +            super(m, p, b); this.nextRight = nextRight;
5822 +            this.transformer = transformer;
5823 +            this.basis = basis; this.reducer = reducer;
5824 +        }
5825 +        @SuppressWarnings("unchecked") public final boolean exec() {
5826 +            final ObjectToDouble<? super K> transformer =
5827 +                this.transformer;
5828 +            final DoubleByDoubleToDouble reducer = this.reducer;
5829 +            if (transformer == null || reducer == null)
5830 +                return abortOnNullFunction();
5831 +            try {
5832 +                final double id = this.basis;
5833 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5834 +                    do {} while (!casPending(c = pending, c+1));
5835 +                    (rights = new MapReduceKeysToDoubleTask<K,V>
5836 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
5837 +                }
5838 +                double r = id;
5839 +                while (advance() != null)
5840 +                    r = reducer.apply(r, transformer.apply((K)nextKey));
5841 +                result = r;
5842 +                for (MapReduceKeysToDoubleTask<K,V> t = this, s;;) {
5843 +                    int c; BulkTask<K,V,?> par;
5844 +                    if ((c = t.pending) == 0) {
5845 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5846 +                            t.result = reducer.apply(t.result, s.result);
5847 +                        }
5848 +                        if ((par = t.parent) == null ||
5849 +                            !(par instanceof MapReduceKeysToDoubleTask)) {
5850 +                            t.quietlyComplete();
5851 +                            break;
5852 +                        }
5853 +                        t = (MapReduceKeysToDoubleTask<K,V>)par;
5854 +                    }
5855 +                    else if (t.casPending(c, c - 1))
5856 +                        break;
5857 +                }
5858 +            } catch (Throwable ex) {
5859 +                return tryCompleteComputation(ex);
5860 +            }
5861 +            return false;
5862 +        }
5863 +        public final Double getRawResult() { return result; }
5864 +    }
5865 +
5866 +    @SuppressWarnings("serial") static final class MapReduceValuesToDoubleTask<K,V>
5867 +        extends BulkTask<K,V,Double> {
5868 +        final ObjectToDouble<? super V> transformer;
5869 +        final DoubleByDoubleToDouble reducer;
5870 +        final double basis;
5871 +        double result;
5872 +        MapReduceValuesToDoubleTask<K,V> rights, nextRight;
5873 +        MapReduceValuesToDoubleTask
5874 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5875 +             MapReduceValuesToDoubleTask<K,V> nextRight,
5876 +             ObjectToDouble<? super V> transformer,
5877 +             double basis,
5878 +             DoubleByDoubleToDouble reducer) {
5879 +            super(m, p, b); this.nextRight = nextRight;
5880 +            this.transformer = transformer;
5881 +            this.basis = basis; this.reducer = reducer;
5882 +        }
5883 +        @SuppressWarnings("unchecked") public final boolean exec() {
5884 +            final ObjectToDouble<? super V> transformer =
5885 +                this.transformer;
5886 +            final DoubleByDoubleToDouble reducer = this.reducer;
5887 +            if (transformer == null || reducer == null)
5888 +                return abortOnNullFunction();
5889 +            try {
5890 +                final double id = this.basis;
5891 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5892 +                    do {} while (!casPending(c = pending, c+1));
5893 +                    (rights = new MapReduceValuesToDoubleTask<K,V>
5894 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
5895 +                }
5896 +                double r = id;
5897 +                Object v;
5898 +                while ((v = advance()) != null)
5899 +                    r = reducer.apply(r, transformer.apply((V)v));
5900 +                result = r;
5901 +                for (MapReduceValuesToDoubleTask<K,V> t = this, s;;) {
5902 +                    int c; BulkTask<K,V,?> par;
5903 +                    if ((c = t.pending) == 0) {
5904 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5905 +                            t.result = reducer.apply(t.result, s.result);
5906 +                        }
5907 +                        if ((par = t.parent) == null ||
5908 +                            !(par instanceof MapReduceValuesToDoubleTask)) {
5909 +                            t.quietlyComplete();
5910 +                            break;
5911 +                        }
5912 +                        t = (MapReduceValuesToDoubleTask<K,V>)par;
5913 +                    }
5914 +                    else if (t.casPending(c, c - 1))
5915 +                        break;
5916 +                }
5917 +            } catch (Throwable ex) {
5918 +                return tryCompleteComputation(ex);
5919 +            }
5920 +            return false;
5921 +        }
5922 +        public final Double getRawResult() { return result; }
5923 +    }
5924 +
5925 +    @SuppressWarnings("serial") static final class MapReduceEntriesToDoubleTask<K,V>
5926 +        extends BulkTask<K,V,Double> {
5927 +        final ObjectToDouble<Map.Entry<K,V>> transformer;
5928 +        final DoubleByDoubleToDouble reducer;
5929 +        final double basis;
5930 +        double result;
5931 +        MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
5932 +        MapReduceEntriesToDoubleTask
5933 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5934 +             MapReduceEntriesToDoubleTask<K,V> nextRight,
5935 +             ObjectToDouble<Map.Entry<K,V>> transformer,
5936 +             double basis,
5937 +             DoubleByDoubleToDouble reducer) {
5938 +            super(m, p, b); this.nextRight = nextRight;
5939 +            this.transformer = transformer;
5940 +            this.basis = basis; this.reducer = reducer;
5941 +        }
5942 +        @SuppressWarnings("unchecked") public final boolean exec() {
5943 +            final ObjectToDouble<Map.Entry<K,V>> transformer =
5944 +                this.transformer;
5945 +            final DoubleByDoubleToDouble reducer = this.reducer;
5946 +            if (transformer == null || reducer == null)
5947 +                return abortOnNullFunction();
5948 +            try {
5949 +                final double id = this.basis;
5950 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
5951 +                    do {} while (!casPending(c = pending, c+1));
5952 +                    (rights = new MapReduceEntriesToDoubleTask<K,V>
5953 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
5954 +                }
5955 +                double r = id;
5956 +                Object v;
5957 +                while ((v = advance()) != null)
5958 +                    r = reducer.apply(r, transformer.apply(entryFor((K)nextKey, (V)v)));
5959 +                result = r;
5960 +                for (MapReduceEntriesToDoubleTask<K,V> t = this, s;;) {
5961 +                    int c; BulkTask<K,V,?> par;
5962 +                    if ((c = t.pending) == 0) {
5963 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
5964 +                            t.result = reducer.apply(t.result, s.result);
5965 +                        }
5966 +                        if ((par = t.parent) == null ||
5967 +                            !(par instanceof MapReduceEntriesToDoubleTask)) {
5968 +                            t.quietlyComplete();
5969 +                            break;
5970 +                        }
5971 +                        t = (MapReduceEntriesToDoubleTask<K,V>)par;
5972 +                    }
5973 +                    else if (t.casPending(c, c - 1))
5974 +                        break;
5975 +                }
5976 +            } catch (Throwable ex) {
5977 +                return tryCompleteComputation(ex);
5978 +            }
5979 +            return false;
5980 +        }
5981 +        public final Double getRawResult() { return result; }
5982 +    }
5983 +
5984 +    @SuppressWarnings("serial") static final class MapReduceMappingsToDoubleTask<K,V>
5985 +        extends BulkTask<K,V,Double> {
5986 +        final ObjectByObjectToDouble<? super K, ? super V> transformer;
5987 +        final DoubleByDoubleToDouble reducer;
5988 +        final double basis;
5989 +        double result;
5990 +        MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
5991 +        MapReduceMappingsToDoubleTask
5992 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
5993 +             MapReduceMappingsToDoubleTask<K,V> nextRight,
5994 +             ObjectByObjectToDouble<? super K, ? super V> transformer,
5995 +             double basis,
5996 +             DoubleByDoubleToDouble reducer) {
5997 +            super(m, p, b); this.nextRight = nextRight;
5998 +            this.transformer = transformer;
5999 +            this.basis = basis; this.reducer = reducer;
6000 +        }
6001 +        @SuppressWarnings("unchecked") public final boolean exec() {
6002 +            final ObjectByObjectToDouble<? super K, ? super V> transformer =
6003 +                this.transformer;
6004 +            final DoubleByDoubleToDouble reducer = this.reducer;
6005 +            if (transformer == null || reducer == null)
6006 +                return abortOnNullFunction();
6007 +            try {
6008 +                final double id = this.basis;
6009 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6010 +                    do {} while (!casPending(c = pending, c+1));
6011 +                    (rights = new MapReduceMappingsToDoubleTask<K,V>
6012 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6013 +                }
6014 +                double r = id;
6015 +                Object v;
6016 +                while ((v = advance()) != null)
6017 +                    r = reducer.apply(r, transformer.apply((K)nextKey, (V)v));
6018 +                result = r;
6019 +                for (MapReduceMappingsToDoubleTask<K,V> t = this, s;;) {
6020 +                    int c; BulkTask<K,V,?> par;
6021 +                    if ((c = t.pending) == 0) {
6022 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6023 +                            t.result = reducer.apply(t.result, s.result);
6024 +                        }
6025 +                        if ((par = t.parent) == null ||
6026 +                            !(par instanceof MapReduceMappingsToDoubleTask)) {
6027 +                            t.quietlyComplete();
6028 +                            break;
6029 +                        }
6030 +                        t = (MapReduceMappingsToDoubleTask<K,V>)par;
6031 +                    }
6032 +                    else if (t.casPending(c, c - 1))
6033 +                        break;
6034 +                }
6035 +            } catch (Throwable ex) {
6036 +                return tryCompleteComputation(ex);
6037 +            }
6038 +            return false;
6039 +        }
6040 +        public final Double getRawResult() { return result; }
6041 +    }
6042 +
6043 +    @SuppressWarnings("serial") static final class MapReduceKeysToLongTask<K,V>
6044 +        extends BulkTask<K,V,Long> {
6045 +        final ObjectToLong<? super K> transformer;
6046 +        final LongByLongToLong reducer;
6047 +        final long basis;
6048 +        long result;
6049 +        MapReduceKeysToLongTask<K,V> rights, nextRight;
6050 +        MapReduceKeysToLongTask
6051 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6052 +             MapReduceKeysToLongTask<K,V> nextRight,
6053 +             ObjectToLong<? super K> transformer,
6054 +             long basis,
6055 +             LongByLongToLong reducer) {
6056 +            super(m, p, b); this.nextRight = nextRight;
6057 +            this.transformer = transformer;
6058 +            this.basis = basis; this.reducer = reducer;
6059 +        }
6060 +        @SuppressWarnings("unchecked") public final boolean exec() {
6061 +            final ObjectToLong<? super K> transformer =
6062 +                this.transformer;
6063 +            final LongByLongToLong reducer = this.reducer;
6064 +            if (transformer == null || reducer == null)
6065 +                return abortOnNullFunction();
6066 +            try {
6067 +                final long id = this.basis;
6068 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6069 +                    do {} while (!casPending(c = pending, c+1));
6070 +                    (rights = new MapReduceKeysToLongTask<K,V>
6071 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6072 +                }
6073 +                long r = id;
6074 +                while (advance() != null)
6075 +                    r = reducer.apply(r, transformer.apply((K)nextKey));
6076 +                result = r;
6077 +                for (MapReduceKeysToLongTask<K,V> t = this, s;;) {
6078 +                    int c; BulkTask<K,V,?> par;
6079 +                    if ((c = t.pending) == 0) {
6080 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6081 +                            t.result = reducer.apply(t.result, s.result);
6082 +                        }
6083 +                        if ((par = t.parent) == null ||
6084 +                            !(par instanceof MapReduceKeysToLongTask)) {
6085 +                            t.quietlyComplete();
6086 +                            break;
6087 +                        }
6088 +                        t = (MapReduceKeysToLongTask<K,V>)par;
6089 +                    }
6090 +                    else if (t.casPending(c, c - 1))
6091 +                        break;
6092 +                }
6093 +            } catch (Throwable ex) {
6094 +                return tryCompleteComputation(ex);
6095 +            }
6096 +            return false;
6097 +        }
6098 +        public final Long getRawResult() { return result; }
6099 +    }
6100 +
6101 +    @SuppressWarnings("serial") static final class MapReduceValuesToLongTask<K,V>
6102 +        extends BulkTask<K,V,Long> {
6103 +        final ObjectToLong<? super V> transformer;
6104 +        final LongByLongToLong reducer;
6105 +        final long basis;
6106 +        long result;
6107 +        MapReduceValuesToLongTask<K,V> rights, nextRight;
6108 +        MapReduceValuesToLongTask
6109 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6110 +             MapReduceValuesToLongTask<K,V> nextRight,
6111 +             ObjectToLong<? super V> transformer,
6112 +             long basis,
6113 +             LongByLongToLong reducer) {
6114 +            super(m, p, b); this.nextRight = nextRight;
6115 +            this.transformer = transformer;
6116 +            this.basis = basis; this.reducer = reducer;
6117 +        }
6118 +        @SuppressWarnings("unchecked") public final boolean exec() {
6119 +            final ObjectToLong<? super V> transformer =
6120 +                this.transformer;
6121 +            final LongByLongToLong reducer = this.reducer;
6122 +            if (transformer == null || reducer == null)
6123 +                return abortOnNullFunction();
6124 +            try {
6125 +                final long id = this.basis;
6126 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6127 +                    do {} while (!casPending(c = pending, c+1));
6128 +                    (rights = new MapReduceValuesToLongTask<K,V>
6129 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6130 +                }
6131 +                long r = id;
6132 +                Object v;
6133 +                while ((v = advance()) != null)
6134 +                    r = reducer.apply(r, transformer.apply((V)v));
6135 +                result = r;
6136 +                for (MapReduceValuesToLongTask<K,V> t = this, s;;) {
6137 +                    int c; BulkTask<K,V,?> par;
6138 +                    if ((c = t.pending) == 0) {
6139 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6140 +                            t.result = reducer.apply(t.result, s.result);
6141 +                        }
6142 +                        if ((par = t.parent) == null ||
6143 +                            !(par instanceof MapReduceValuesToLongTask)) {
6144 +                            t.quietlyComplete();
6145 +                            break;
6146 +                        }
6147 +                        t = (MapReduceValuesToLongTask<K,V>)par;
6148 +                    }
6149 +                    else if (t.casPending(c, c - 1))
6150 +                        break;
6151 +                }
6152 +            } catch (Throwable ex) {
6153 +                return tryCompleteComputation(ex);
6154 +            }
6155 +            return false;
6156 +        }
6157 +        public final Long getRawResult() { return result; }
6158 +    }
6159 +
6160 +    @SuppressWarnings("serial") static final class MapReduceEntriesToLongTask<K,V>
6161 +        extends BulkTask<K,V,Long> {
6162 +        final ObjectToLong<Map.Entry<K,V>> transformer;
6163 +        final LongByLongToLong reducer;
6164 +        final long basis;
6165 +        long result;
6166 +        MapReduceEntriesToLongTask<K,V> rights, nextRight;
6167 +        MapReduceEntriesToLongTask
6168 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6169 +             MapReduceEntriesToLongTask<K,V> nextRight,
6170 +             ObjectToLong<Map.Entry<K,V>> transformer,
6171 +             long basis,
6172 +             LongByLongToLong reducer) {
6173 +            super(m, p, b); this.nextRight = nextRight;
6174 +            this.transformer = transformer;
6175 +            this.basis = basis; this.reducer = reducer;
6176 +        }
6177 +        @SuppressWarnings("unchecked") public final boolean exec() {
6178 +            final ObjectToLong<Map.Entry<K,V>> transformer =
6179 +                this.transformer;
6180 +            final LongByLongToLong reducer = this.reducer;
6181 +            if (transformer == null || reducer == null)
6182 +                return abortOnNullFunction();
6183 +            try {
6184 +                final long id = this.basis;
6185 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6186 +                    do {} while (!casPending(c = pending, c+1));
6187 +                    (rights = new MapReduceEntriesToLongTask<K,V>
6188 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6189 +                }
6190 +                long r = id;
6191 +                Object v;
6192 +                while ((v = advance()) != null)
6193 +                    r = reducer.apply(r, transformer.apply(entryFor((K)nextKey, (V)v)));
6194 +                result = r;
6195 +                for (MapReduceEntriesToLongTask<K,V> t = this, s;;) {
6196 +                    int c; BulkTask<K,V,?> par;
6197 +                    if ((c = t.pending) == 0) {
6198 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6199 +                            t.result = reducer.apply(t.result, s.result);
6200 +                        }
6201 +                        if ((par = t.parent) == null ||
6202 +                            !(par instanceof MapReduceEntriesToLongTask)) {
6203 +                            t.quietlyComplete();
6204 +                            break;
6205 +                        }
6206 +                        t = (MapReduceEntriesToLongTask<K,V>)par;
6207 +                    }
6208 +                    else if (t.casPending(c, c - 1))
6209 +                        break;
6210 +                }
6211 +            } catch (Throwable ex) {
6212 +                return tryCompleteComputation(ex);
6213 +            }
6214 +            return false;
6215 +        }
6216 +        public final Long getRawResult() { return result; }
6217 +    }
6218 +
6219 +    @SuppressWarnings("serial") static final class MapReduceMappingsToLongTask<K,V>
6220 +        extends BulkTask<K,V,Long> {
6221 +        final ObjectByObjectToLong<? super K, ? super V> transformer;
6222 +        final LongByLongToLong reducer;
6223 +        final long basis;
6224 +        long result;
6225 +        MapReduceMappingsToLongTask<K,V> rights, nextRight;
6226 +        MapReduceMappingsToLongTask
6227 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6228 +             MapReduceMappingsToLongTask<K,V> nextRight,
6229 +             ObjectByObjectToLong<? super K, ? super V> transformer,
6230 +             long basis,
6231 +             LongByLongToLong reducer) {
6232 +            super(m, p, b); this.nextRight = nextRight;
6233 +            this.transformer = transformer;
6234 +            this.basis = basis; this.reducer = reducer;
6235 +        }
6236 +        @SuppressWarnings("unchecked") public final boolean exec() {
6237 +            final ObjectByObjectToLong<? super K, ? super V> transformer =
6238 +                this.transformer;
6239 +            final LongByLongToLong reducer = this.reducer;
6240 +            if (transformer == null || reducer == null)
6241 +                return abortOnNullFunction();
6242 +            try {
6243 +                final long id = this.basis;
6244 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6245 +                    do {} while (!casPending(c = pending, c+1));
6246 +                    (rights = new MapReduceMappingsToLongTask<K,V>
6247 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6248 +                }
6249 +                long r = id;
6250 +                Object v;
6251 +                while ((v = advance()) != null)
6252 +                    r = reducer.apply(r, transformer.apply((K)nextKey, (V)v));
6253 +                result = r;
6254 +                for (MapReduceMappingsToLongTask<K,V> t = this, s;;) {
6255 +                    int c; BulkTask<K,V,?> par;
6256 +                    if ((c = t.pending) == 0) {
6257 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6258 +                            t.result = reducer.apply(t.result, s.result);
6259 +                        }
6260 +                        if ((par = t.parent) == null ||
6261 +                            !(par instanceof MapReduceMappingsToLongTask)) {
6262 +                            t.quietlyComplete();
6263 +                            break;
6264 +                        }
6265 +                        t = (MapReduceMappingsToLongTask<K,V>)par;
6266 +                    }
6267 +                    else if (t.casPending(c, c - 1))
6268 +                        break;
6269 +                }
6270 +            } catch (Throwable ex) {
6271 +                return tryCompleteComputation(ex);
6272 +            }
6273 +            return false;
6274 +        }
6275 +        public final Long getRawResult() { return result; }
6276 +    }
6277 +
6278 +    @SuppressWarnings("serial") static final class MapReduceKeysToIntTask<K,V>
6279 +        extends BulkTask<K,V,Integer> {
6280 +        final ObjectToInt<? super K> transformer;
6281 +        final IntByIntToInt reducer;
6282 +        final int basis;
6283 +        int result;
6284 +        MapReduceKeysToIntTask<K,V> rights, nextRight;
6285 +        MapReduceKeysToIntTask
6286 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6287 +             MapReduceKeysToIntTask<K,V> nextRight,
6288 +             ObjectToInt<? super K> transformer,
6289 +             int basis,
6290 +             IntByIntToInt reducer) {
6291 +            super(m, p, b); this.nextRight = nextRight;
6292 +            this.transformer = transformer;
6293 +            this.basis = basis; this.reducer = reducer;
6294 +        }
6295 +        @SuppressWarnings("unchecked") public final boolean exec() {
6296 +            final ObjectToInt<? super K> transformer =
6297 +                this.transformer;
6298 +            final IntByIntToInt reducer = this.reducer;
6299 +            if (transformer == null || reducer == null)
6300 +                return abortOnNullFunction();
6301 +            try {
6302 +                final int id = this.basis;
6303 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6304 +                    do {} while (!casPending(c = pending, c+1));
6305 +                    (rights = new MapReduceKeysToIntTask<K,V>
6306 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6307 +                }
6308 +                int r = id;
6309 +                while (advance() != null)
6310 +                    r = reducer.apply(r, transformer.apply((K)nextKey));
6311 +                result = r;
6312 +                for (MapReduceKeysToIntTask<K,V> t = this, s;;) {
6313 +                    int c; BulkTask<K,V,?> par;
6314 +                    if ((c = t.pending) == 0) {
6315 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6316 +                            t.result = reducer.apply(t.result, s.result);
6317 +                        }
6318 +                        if ((par = t.parent) == null ||
6319 +                            !(par instanceof MapReduceKeysToIntTask)) {
6320 +                            t.quietlyComplete();
6321 +                            break;
6322 +                        }
6323 +                        t = (MapReduceKeysToIntTask<K,V>)par;
6324 +                    }
6325 +                    else if (t.casPending(c, c - 1))
6326 +                        break;
6327 +                }
6328 +            } catch (Throwable ex) {
6329 +                return tryCompleteComputation(ex);
6330 +            }
6331 +            return false;
6332 +        }
6333 +        public final Integer getRawResult() { return result; }
6334 +    }
6335 +
6336 +    @SuppressWarnings("serial") static final class MapReduceValuesToIntTask<K,V>
6337 +        extends BulkTask<K,V,Integer> {
6338 +        final ObjectToInt<? super V> transformer;
6339 +        final IntByIntToInt reducer;
6340 +        final int basis;
6341 +        int result;
6342 +        MapReduceValuesToIntTask<K,V> rights, nextRight;
6343 +        MapReduceValuesToIntTask
6344 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6345 +             MapReduceValuesToIntTask<K,V> nextRight,
6346 +             ObjectToInt<? super V> transformer,
6347 +             int basis,
6348 +             IntByIntToInt reducer) {
6349 +            super(m, p, b); this.nextRight = nextRight;
6350 +            this.transformer = transformer;
6351 +            this.basis = basis; this.reducer = reducer;
6352 +        }
6353 +        @SuppressWarnings("unchecked") public final boolean exec() {
6354 +            final ObjectToInt<? super V> transformer =
6355 +                this.transformer;
6356 +            final IntByIntToInt reducer = this.reducer;
6357 +            if (transformer == null || reducer == null)
6358 +                return abortOnNullFunction();
6359 +            try {
6360 +                final int id = this.basis;
6361 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6362 +                    do {} while (!casPending(c = pending, c+1));
6363 +                    (rights = new MapReduceValuesToIntTask<K,V>
6364 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6365 +                }
6366 +                int r = id;
6367 +                Object v;
6368 +                while ((v = advance()) != null)
6369 +                    r = reducer.apply(r, transformer.apply((V)v));
6370 +                result = r;
6371 +                for (MapReduceValuesToIntTask<K,V> t = this, s;;) {
6372 +                    int c; BulkTask<K,V,?> par;
6373 +                    if ((c = t.pending) == 0) {
6374 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6375 +                            t.result = reducer.apply(t.result, s.result);
6376 +                        }
6377 +                        if ((par = t.parent) == null ||
6378 +                            !(par instanceof MapReduceValuesToIntTask)) {
6379 +                            t.quietlyComplete();
6380 +                            break;
6381 +                        }
6382 +                        t = (MapReduceValuesToIntTask<K,V>)par;
6383 +                    }
6384 +                    else if (t.casPending(c, c - 1))
6385 +                        break;
6386 +                }
6387 +            } catch (Throwable ex) {
6388 +                return tryCompleteComputation(ex);
6389 +            }
6390 +            return false;
6391 +        }
6392 +        public final Integer getRawResult() { return result; }
6393 +    }
6394 +
6395 +    @SuppressWarnings("serial") static final class MapReduceEntriesToIntTask<K,V>
6396 +        extends BulkTask<K,V,Integer> {
6397 +        final ObjectToInt<Map.Entry<K,V>> transformer;
6398 +        final IntByIntToInt reducer;
6399 +        final int basis;
6400 +        int result;
6401 +        MapReduceEntriesToIntTask<K,V> rights, nextRight;
6402 +        MapReduceEntriesToIntTask
6403 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6404 +             MapReduceEntriesToIntTask<K,V> nextRight,
6405 +             ObjectToInt<Map.Entry<K,V>> transformer,
6406 +             int basis,
6407 +             IntByIntToInt reducer) {
6408 +            super(m, p, b); this.nextRight = nextRight;
6409 +            this.transformer = transformer;
6410 +            this.basis = basis; this.reducer = reducer;
6411 +        }
6412 +        @SuppressWarnings("unchecked") public final boolean exec() {
6413 +            final ObjectToInt<Map.Entry<K,V>> transformer =
6414 +                this.transformer;
6415 +            final IntByIntToInt reducer = this.reducer;
6416 +            if (transformer == null || reducer == null)
6417 +                return abortOnNullFunction();
6418 +            try {
6419 +                final int id = this.basis;
6420 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6421 +                    do {} while (!casPending(c = pending, c+1));
6422 +                    (rights = new MapReduceEntriesToIntTask<K,V>
6423 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6424 +                }
6425 +                int r = id;
6426 +                Object v;
6427 +                while ((v = advance()) != null)
6428 +                    r = reducer.apply(r, transformer.apply(entryFor((K)nextKey, (V)v)));
6429 +                result = r;
6430 +                for (MapReduceEntriesToIntTask<K,V> t = this, s;;) {
6431 +                    int c; BulkTask<K,V,?> par;
6432 +                    if ((c = t.pending) == 0) {
6433 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6434 +                            t.result = reducer.apply(t.result, s.result);
6435 +                        }
6436 +                        if ((par = t.parent) == null ||
6437 +                            !(par instanceof MapReduceEntriesToIntTask)) {
6438 +                            t.quietlyComplete();
6439 +                            break;
6440 +                        }
6441 +                        t = (MapReduceEntriesToIntTask<K,V>)par;
6442 +                    }
6443 +                    else if (t.casPending(c, c - 1))
6444 +                        break;
6445 +                }
6446 +            } catch (Throwable ex) {
6447 +                return tryCompleteComputation(ex);
6448 +            }
6449 +            return false;
6450 +        }
6451 +        public final Integer getRawResult() { return result; }
6452 +    }
6453 +
6454 +    @SuppressWarnings("serial") static final class MapReduceMappingsToIntTask<K,V>
6455 +        extends BulkTask<K,V,Integer> {
6456 +        final ObjectByObjectToInt<? super K, ? super V> transformer;
6457 +        final IntByIntToInt reducer;
6458 +        final int basis;
6459 +        int result;
6460 +        MapReduceMappingsToIntTask<K,V> rights, nextRight;
6461 +        MapReduceMappingsToIntTask
6462 +            (ConcurrentHashMapV8<K,V> m, BulkTask<K,V,?> p, int b,
6463 +             MapReduceMappingsToIntTask<K,V> rights,
6464 +             ObjectByObjectToInt<? super K, ? super V> transformer,
6465 +             int basis,
6466 +             IntByIntToInt reducer) {
6467 +            super(m, p, b); this.nextRight = nextRight;
6468 +            this.transformer = transformer;
6469 +            this.basis = basis; this.reducer = reducer;
6470 +        }
6471 +        @SuppressWarnings("unchecked") public final boolean exec() {
6472 +            final ObjectByObjectToInt<? super K, ? super V> transformer =
6473 +                this.transformer;
6474 +            final IntByIntToInt reducer = this.reducer;
6475 +            if (transformer == null || reducer == null)
6476 +                return abortOnNullFunction();
6477 +            try {
6478 +                final int id = this.basis;
6479 +                for (int c, b = batch(); b > 1 && baseIndex != baseLimit;) {
6480 +                    do {} while (!casPending(c = pending, c+1));
6481 +                    (rights = new MapReduceMappingsToIntTask<K,V>
6482 +                     (map, this, b >>>= 1, rights, transformer, id, reducer)).fork();
6483 +                }
6484 +                int r = id;
6485 +                Object v;
6486 +                while ((v = advance()) != null)
6487 +                    r = reducer.apply(r, transformer.apply((K)nextKey, (V)v));
6488 +                result = r;
6489 +                for (MapReduceMappingsToIntTask<K,V> t = this, s;;) {
6490 +                    int c; BulkTask<K,V,?> par;
6491 +                    if ((c = t.pending) == 0) {
6492 +                        for (s = t.rights; s != null; s = t.rights = s.nextRight) {
6493 +                            t.result = reducer.apply(t.result, s.result);
6494 +                        }
6495 +                        if ((par = t.parent) == null ||
6496 +                            !(par instanceof MapReduceMappingsToIntTask)) {
6497 +                            t.quietlyComplete();
6498 +                            break;
6499 +                        }
6500 +                        t = (MapReduceMappingsToIntTask<K,V>)par;
6501 +                    }
6502 +                    else if (t.casPending(c, c - 1))
6503 +                        break;
6504 +                }
6505 +            } catch (Throwable ex) {
6506 +                return tryCompleteComputation(ex);
6507 +            }
6508 +            return false;
6509 +        }
6510 +        public final Integer getRawResult() { return result; }
6511 +    }
6512 +
6513 +
6514      // Unsafe mechanics
6515      private static final sun.misc.Unsafe UNSAFE;
6516      private static final long counterOffset;
6517 <    private static final long resizingOffset;
6517 >    private static final long sizeCtlOffset;
6518      private static final long ABASE;
6519      private static final int ASHIFT;
6520  
# Line 1693 | Line 6525 | public class ConcurrentHashMapV8<K, V>
6525              Class<?> k = ConcurrentHashMapV8.class;
6526              counterOffset = UNSAFE.objectFieldOffset
6527                  (k.getDeclaredField("counter"));
6528 <            resizingOffset = UNSAFE.objectFieldOffset
6529 <                (k.getDeclaredField("resizing"));
6528 >            sizeCtlOffset = UNSAFE.objectFieldOffset
6529 >                (k.getDeclaredField("sizeCtl"));
6530              Class<?> sc = Node[].class;
6531              ABASE = UNSAFE.arrayBaseOffset(sc);
6532              ss = UNSAFE.arrayIndexScale(sc);
# Line 1733 | Line 6565 | public class ConcurrentHashMapV8<K, V>
6565              }
6566          }
6567      }
1736
6568   }

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