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Revision 1.5 by dl, Tue Aug 30 11:35:39 2011 UTC vs.
Revision 1.101 by jsr166, Tue Jun 18 17:57:21 2013 UTC

# Line 5 | Line 5
5   */
6  
7   package jsr166e;
8 < import jsr166e.LongAdder;
8 >
9 > import java.util.Comparator;
10 > import java.util.Arrays;
11   import java.util.Map;
12   import java.util.Set;
13   import java.util.Collection;
# Line 19 | Line 21 | import java.util.Enumeration;
21   import java.util.ConcurrentModificationException;
22   import java.util.NoSuchElementException;
23   import java.util.concurrent.ConcurrentMap;
24 + import java.util.concurrent.locks.AbstractQueuedSynchronizer;
25 + import java.util.concurrent.atomic.AtomicInteger;
26 + import java.util.concurrent.atomic.AtomicReference;
27   import java.io.Serializable;
28  
29   /**
# Line 33 | Line 38 | import java.io.Serializable;
38   * interoperable with {@code Hashtable} in programs that rely on its
39   * thread safety but not on its synchronization details.
40   *
41 < * <p> Retrieval operations (including {@code get}) generally do not
41 > * <p>Retrieval operations (including {@code get}) generally do not
42   * block, so may overlap with update operations (including {@code put}
43   * and {@code remove}). Retrievals reflect the results of the most
44   * recently <em>completed</em> update operations holding upon their
45 < * onset.  For aggregate operations such as {@code putAll} and {@code
46 < * clear}, concurrent retrievals may reflect insertion or removal of
47 < * only some entries.  Similarly, Iterators and Enumerations return
48 < * elements reflecting the state of the hash table at some point at or
49 < * since the creation of the iterator/enumeration.  They do
50 < * <em>not</em> throw {@link ConcurrentModificationException}.
51 < * However, iterators are designed to be used by only one thread at a
52 < * time.  Bear in mind that the results of aggregate status methods
53 < * including {@code size}, {@code isEmpty}, and {@code containsValue}
54 < * are typically useful only when a map is not undergoing concurrent
55 < * updates in other threads.  Otherwise the results of these methods
56 < * reflect transient states that may be adequate for monitoring
57 < * purposes, but not for program control.
58 < *
59 < * <p> Resizing this or any other kind of hash table is a relatively
60 < * slow operation, so, when possible, it is a good idea to provide
61 < * estimates of expected table sizes in constructors. Also, for
62 < * compatability with previous versions of this class, constructors
63 < * may optionally specify an expected {@code concurrencyLevel} as an
64 < * additional hint for internal sizing.
45 > * onset. (More formally, an update operation for a given key bears a
46 > * <em>happens-before</em> relation with any (non-null) retrieval for
47 > * that key reporting the updated value.)  For aggregate operations
48 > * such as {@code putAll} and {@code clear}, concurrent retrievals may
49 > * reflect insertion or removal of only some entries.  Similarly,
50 > * Iterators and Enumerations return elements reflecting the state of
51 > * the hash table at some point at or since the creation of the
52 > * iterator/enumeration.  They do <em>not</em> throw {@link
53 > * ConcurrentModificationException}.  However, iterators are designed
54 > * to be used by only one thread at a time.  Bear in mind that the
55 > * results of aggregate status methods including {@code size}, {@code
56 > * isEmpty}, and {@code containsValue} are typically useful only when
57 > * a map is not undergoing concurrent updates in other threads.
58 > * Otherwise the results of these methods reflect transient states
59 > * that may be adequate for monitoring or estimation purposes, but not
60 > * for program control.
61 > *
62 > * <p>The table is dynamically expanded when there are too many
63 > * collisions (i.e., keys that have distinct hash codes but fall into
64 > * the same slot modulo the table size), with the expected average
65 > * effect of maintaining roughly two bins per mapping (corresponding
66 > * to a 0.75 load factor threshold for resizing). There may be much
67 > * variance around this average as mappings are added and removed, but
68 > * overall, this maintains a commonly accepted time/space tradeoff for
69 > * hash tables.  However, resizing this or any other kind of hash
70 > * table may be a relatively slow operation. When possible, it is a
71 > * good idea to provide a size estimate as an optional {@code
72 > * initialCapacity} constructor argument. An additional optional
73 > * {@code loadFactor} constructor argument provides a further means of
74 > * customizing initial table capacity by specifying the table density
75 > * to be used in calculating the amount of space to allocate for the
76 > * given number of elements.  Also, for compatibility with previous
77 > * versions of this class, constructors may optionally specify an
78 > * expected {@code concurrencyLevel} as an additional hint for
79 > * internal sizing.  Note that using many keys with exactly the same
80 > * {@code hashCode()} is a sure way to slow down performance of any
81 > * hash table.
82 > *
83 > * <p>A {@link Set} projection of a ConcurrentHashMapV8 may be created
84 > * (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed
85 > * (using {@link #keySet(Object)} when only keys are of interest, and the
86 > * mapped values are (perhaps transiently) not used or all take the
87 > * same mapping value.
88 > *
89 > * <p>A ConcurrentHashMapV8 can be used as scalable frequency map (a
90 > * form of histogram or multiset) by using {@link LongAdder} values
91 > * and initializing via {@link #computeIfAbsent}. For example, to add
92 > * a count to a {@code ConcurrentHashMapV8<String,LongAdder> freqs}, you
93 > * can use {@code freqs.computeIfAbsent(k -> new
94 > * LongAdder()).increment();}
95   *
96   * <p>This class and its views and iterators implement all of the
97   * <em>optional</em> methods of the {@link Map} and {@link Iterator}
98   * interfaces.
99   *
100 < * <p> Like {@link Hashtable} but unlike {@link HashMap}, this class
100 > * <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
101   * does <em>not</em> allow {@code null} to be used as a key or value.
102   *
103 + * <p>ConcurrentHashMapV8s support sequential and parallel operations
104 + * bulk operations. (Parallel forms use the {@link
105 + * ForkJoinPool#commonPool()}). Tasks that may be used in other
106 + * contexts are available in class {@link ForkJoinTasks}. These
107 + * operations are designed to be safely, and often sensibly, applied
108 + * even with maps that are being concurrently updated by other
109 + * threads; for example, when computing a snapshot summary of the
110 + * values in a shared registry.  There are three kinds of operation,
111 + * each with four forms, accepting functions with Keys, Values,
112 + * Entries, and (Key, Value) arguments and/or return values. Because
113 + * the elements of a ConcurrentHashMapV8 are not ordered in any
114 + * particular way, and may be processed in different orders in
115 + * different parallel executions, the correctness of supplied
116 + * functions should not depend on any ordering, or on any other
117 + * objects or values that may transiently change while computation is
118 + * in progress; and except for forEach actions, should ideally be
119 + * side-effect-free.
120 + *
121 + * <ul>
122 + * <li> forEach: Perform a given action on each element.
123 + * A variant form applies a given transformation on each element
124 + * before performing the action.</li>
125 + *
126 + * <li> search: Return the first available non-null result of
127 + * applying a given function on each element; skipping further
128 + * search when a result is found.</li>
129 + *
130 + * <li> reduce: Accumulate each element.  The supplied reduction
131 + * function cannot rely on ordering (more formally, it should be
132 + * both associative and commutative).  There are five variants:
133 + *
134 + * <ul>
135 + *
136 + * <li> Plain reductions. (There is not a form of this method for
137 + * (key, value) function arguments since there is no corresponding
138 + * return type.)</li>
139 + *
140 + * <li> Mapped reductions that accumulate the results of a given
141 + * function applied to each element.</li>
142 + *
143 + * <li> Reductions to scalar doubles, longs, and ints, using a
144 + * given basis value.</li>
145 + *
146 + * </li>
147 + * </ul>
148 + * </ul>
149 + *
150 + * <p>The concurrency properties of bulk operations follow
151 + * from those of ConcurrentHashMapV8: Any non-null result returned
152 + * from {@code get(key)} and related access methods bears a
153 + * happens-before relation with the associated insertion or
154 + * update.  The result of any bulk operation reflects the
155 + * composition of these per-element relations (but is not
156 + * necessarily atomic with respect to the map as a whole unless it
157 + * is somehow known to be quiescent).  Conversely, because keys
158 + * and values in the map are never null, null serves as a reliable
159 + * atomic indicator of the current lack of any result.  To
160 + * maintain this property, null serves as an implicit basis for
161 + * all non-scalar reduction operations. For the double, long, and
162 + * int versions, the basis should be one that, when combined with
163 + * any other value, returns that other value (more formally, it
164 + * should be the identity element for the reduction). Most common
165 + * reductions have these properties; for example, computing a sum
166 + * with basis 0 or a minimum with basis MAX_VALUE.
167 + *
168 + * <p>Search and transformation functions provided as arguments
169 + * should similarly return null to indicate the lack of any result
170 + * (in which case it is not used). In the case of mapped
171 + * reductions, this also enables transformations to serve as
172 + * filters, returning null (or, in the case of primitive
173 + * specializations, the identity basis) if the element should not
174 + * be combined. You can create compound transformations and
175 + * filterings by composing them yourself under this "null means
176 + * there is nothing there now" rule before using them in search or
177 + * reduce operations.
178 + *
179 + * <p>Methods accepting and/or returning Entry arguments maintain
180 + * key-value associations. They may be useful for example when
181 + * finding the key for the greatest value. Note that "plain" Entry
182 + * arguments can be supplied using {@code new
183 + * AbstractMap.SimpleEntry(k,v)}.
184 + *
185 + * <p>Bulk operations may complete abruptly, throwing an
186 + * exception encountered in the application of a supplied
187 + * function. Bear in mind when handling such exceptions that other
188 + * concurrently executing functions could also have thrown
189 + * exceptions, or would have done so if the first exception had
190 + * not occurred.
191 + *
192 + * <p>Speedups for parallel compared to sequential forms are common
193 + * but not guaranteed.  Parallel operations involving brief functions
194 + * on small maps may execute more slowly than sequential forms if the
195 + * underlying work to parallelize the computation is more expensive
196 + * than the computation itself.  Similarly, parallelization may not
197 + * lead to much actual parallelism if all processors are busy
198 + * performing unrelated tasks.
199 + *
200 + * <p>All arguments to all task methods must be non-null.
201 + *
202 + * <p><em>jsr166e note: During transition, this class
203 + * uses nested functional interfaces with different names but the
204 + * same forms as those expected for JDK8.</em>
205 + *
206   * <p>This class is a member of the
207   * <a href="{@docRoot}/../technotes/guides/collections/index.html">
208   * Java Collections Framework</a>.
209   *
72 * <p><em>jsr166e note: This class is a candidate replacement for
73 * java.util.concurrent.ConcurrentHashMap.<em>
74 *
210   * @since 1.5
211   * @author Doug Lea
212   * @param <K> the type of keys maintained by this map
213   * @param <V> the type of mapped values
214   */
215 < public class ConcurrentHashMapV8<K, V>
216 <        implements ConcurrentMap<K, V>, Serializable {
215 > public class ConcurrentHashMapV8<K,V>
216 >    implements ConcurrentMap<K,V>, Serializable {
217      private static final long serialVersionUID = 7249069246763182397L;
218  
219      /**
220 <     * A function computing a mapping from the given key to a value,
221 <     *  or <code>null</code> if there is no mapping. This is a
222 <     * place-holder for an upcoming JDK8 interface.
223 <     */
224 <    public static interface MappingFunction<K, V> {
225 <        /**
226 <         * Returns a value for the given key, or null if there is no
227 <         * mapping. If this function throws an (unchecked) exception,
228 <         * the exception is rethrown to its caller, and no mapping is
229 <         * recorded.  Because this function is invoked within
230 <         * atomicity control, the computation should be short and
231 <         * simple. The most common usage is to construct a new object
232 <         * serving as an initial mapped value.
220 >     * A partitionable iterator. A Spliterator can be traversed
221 >     * directly, but can also be partitioned (before traversal) by
222 >     * creating another Spliterator that covers a non-overlapping
223 >     * portion of the elements, and so may be amenable to parallel
224 >     * execution.
225 >     *
226 >     * <p>This interface exports a subset of expected JDK8
227 >     * functionality.
228 >     *
229 >     * <p>Sample usage: Here is one (of the several) ways to compute
230 >     * the sum of the values held in a map using the ForkJoin
231 >     * framework. As illustrated here, Spliterators are well suited to
232 >     * designs in which a task repeatedly splits off half its work
233 >     * into forked subtasks until small enough to process directly,
234 >     * and then joins these subtasks. Variants of this style can also
235 >     * be used in completion-based designs.
236 >     *
237 >     * <pre>
238 >     * {@code ConcurrentHashMapV8<String, Long> m = ...
239 >     * // split as if have 8 * parallelism, for load balance
240 >     * int n = m.size();
241 >     * int p = aForkJoinPool.getParallelism() * 8;
242 >     * int split = (n < p)? n : p;
243 >     * long sum = aForkJoinPool.invoke(new SumValues(m.valueSpliterator(), split, null));
244 >     * // ...
245 >     * static class SumValues extends RecursiveTask<Long> {
246 >     *   final Spliterator<Long> s;
247 >     *   final int split;             // split while > 1
248 >     *   final SumValues nextJoin;    // records forked subtasks to join
249 >     *   SumValues(Spliterator<Long> s, int depth, SumValues nextJoin) {
250 >     *     this.s = s; this.depth = depth; this.nextJoin = nextJoin;
251 >     *   }
252 >     *   public Long compute() {
253 >     *     long sum = 0;
254 >     *     SumValues subtasks = null; // fork subtasks
255 >     *     for (int s = split >>> 1; s > 0; s >>>= 1)
256 >     *       (subtasks = new SumValues(s.split(), s, subtasks)).fork();
257 >     *     while (s.hasNext())        // directly process remaining elements
258 >     *       sum += s.next();
259 >     *     for (SumValues t = subtasks; t != null; t = t.nextJoin)
260 >     *       sum += t.join();         // collect subtask results
261 >     *     return sum;
262 >     *   }
263 >     * }
264 >     * }</pre>
265 >     */
266 >    public static interface Spliterator<T> extends Iterator<T> {
267 >        /**
268 >         * Returns a Spliterator covering approximately half of the
269 >         * elements, guaranteed not to overlap with those subsequently
270 >         * returned by this Spliterator.  After invoking this method,
271 >         * the current Spliterator will <em>not</em> produce any of
272 >         * the elements of the returned Spliterator, but the two
273 >         * Spliterators together will produce all of the elements that
274 >         * would have been produced by this Spliterator had this
275 >         * method not been called. The exact number of elements
276 >         * produced by the returned Spliterator is not guaranteed, and
277 >         * may be zero (i.e., with {@code hasNext()} reporting {@code
278 >         * false}) if this Spliterator cannot be further split.
279           *
280 <         * @param key the (non-null) key
281 <         * @return a value, or null if none
280 >         * @return a Spliterator covering approximately half of the
281 >         * elements
282 >         * @throws IllegalStateException if this Spliterator has
283 >         * already commenced traversing elements
284           */
285 <        V map(K key);
285 >        Spliterator<T> split();
286      }
287  
288      /*
# Line 108 | Line 291 | public class ConcurrentHashMapV8<K, V>
291       * The primary design goal of this hash table is to maintain
292       * concurrent readability (typically method get(), but also
293       * iterators and related methods) while minimizing update
294 <     * contention.
295 <     *
296 <     * Each key-value mapping is held in a Node.  Because Node fields
297 <     * can contain special values, they are defined using plain Object
298 <     * types. Similarly in turn, all internal methods that use them
299 <     * work off Object types. All public generic-typed methods relay
300 <     * in/out of these internal methods, supplying casts as needed.
294 >     * contention. Secondary goals are to keep space consumption about
295 >     * the same or better than java.util.HashMap, and to support high
296 >     * initial insertion rates on an empty table by many threads.
297 >     *
298 >     * Each key-value mapping is held in a Node.  Because Node key
299 >     * fields can contain special values, they are defined using plain
300 >     * Object types (not type "K"). This leads to a lot of explicit
301 >     * casting (and many explicit warning suppressions to tell
302 >     * compilers not to complain about it). It also allows some of the
303 >     * public methods to be factored into a smaller number of internal
304 >     * methods (although sadly not so for the five variants of
305 >     * put-related operations). The validation-based approach
306 >     * explained below leads to a lot of code sprawl because
307 >     * retry-control precludes factoring into smaller methods.
308       *
309       * The table is lazily initialized to a power-of-two size upon the
310 <     * first insertion.  Each bin in the table contains a (typically
311 <     * short) list of Nodes.  Table accesses require volatile/atomic
312 <     * reads, writes, and CASes.  Because there is no other way to
313 <     * arrange this without adding further indirections, we use
314 <     * intrinsics (sun.misc.Unsafe) operations.  The lists of nodes
315 <     * within bins are always accurately traversable under volatile
316 <     * reads, so long as lookups check hash code and non-nullness of
317 <     * key and value before checking key equality. (All valid hash
318 <     * codes are nonnegative. Negative values are reserved for special
319 <     * forwarding nodes; see below.)
320 <     *
321 <     * A bin may be locked during update (insert, delete, and replace)
322 <     * operations.  We do not want to waste the space required to
323 <     * associate a distinct lock object with each bin, so instead use
324 <     * the first node of a bin list itself as a lock, using builtin
325 <     * "synchronized" locks. These save space and we can live with
326 <     * only plain block-structured lock/unlock operations. Using the
327 <     * first node of a list as a lock does not by itself suffice
328 <     * though: When a node is locked, any update must first validate
329 <     * that it is still the first node, and retry if not. (Because new
330 <     * nodes are always appended to lists, once a node is first in a
331 <     * bin, it remains first until deleted or the bin becomes
332 <     * invalidated.)  However, update operations can and usually do
333 <     * still traverse the bin until the point of update, which helps
334 <     * reduce cache misses on retries.  This is a converse of sorts to
335 <     * the lazy locking technique described by Herlihy & Shavit. If
336 <     * there is no existing node during a put operation, then one can
337 <     * be CAS'ed in (without need for lock except in computeIfAbsent);
338 <     * the CAS serves as validation. This is on average the most
339 <     * common case for put operations -- under random hash codes, the
340 <     * distribution of nodes in bins follows a Poisson distribution
341 <     * (see http://en.wikipedia.org/wiki/Poisson_distribution) with a
342 <     * parameter of 0.5 on average under the default loadFactor of
343 <     * 0.75.  The expected number of locks covering different elements
344 <     * (i.e., bins with 2 or more nodes) is approximately 10% at
345 <     * steady state under default settings.  Lock contention
346 <     * probability for two threads accessing arbitrary distinct
347 <     * elements is, roughly, 1 / (8 * #elements).
348 <     *
349 <     * The table is resized when occupancy exceeds a threshold.  Only
350 <     * a single thread performs the resize (using field "resizing", to
351 <     * arrange exclusion), but the table otherwise remains usable for
352 <     * both reads and updates. Resizing proceeds by transferring bins,
353 <     * one by one, from the table to the next table.  Upon transfer,
354 <     * the old table bin contains only a special forwarding node (with
355 <     * negative hash code ("MOVED")) that contains the next table as
356 <     * its key. On encountering a forwarding node, access and update
357 <     * operations restart, using the new table. To ensure concurrent
358 <     * readability of traversals, transfers must proceed from the last
359 <     * bin (table.length - 1) up towards the first.  Any traversal
360 <     * starting from the first bin can then arrange to move to the new
361 <     * table for the rest of the traversal without revisiting nodes.
362 <     * This constrains bin transfers to a particular order, and so can
363 <     * block indefinitely waiting for the next lock, and other threads
364 <     * cannot help with the transfer. However, expected stalls are
365 <     * infrequent enough to not warrant the additional overhead and
366 <     * complexity of access and iteration schemes that could admit
367 <     * out-of-order or concurrent bin transfers.
368 <     *
369 <     * A similar traversal scheme (not yet implemented) can apply to
370 <     * partial traversals during partitioned aggregate operations.
371 <     * Also, read-only operations give up if ever forwarded to a null
372 <     * table, which provides support for shutdown-style clearing,
373 <     * which is also not currently implemented.
374 <     *
375 <     * The element count is maintained using a LongAdder, which avoids
376 <     * contention on updates but can encounter cache thrashing if read
377 <     * too frequently during concurrent updates. To avoid reading so
378 <     * often, resizing is normally attempted only upon adding to a bin
379 <     * already holding two or more nodes. Under the default threshold
380 <     * (0.75), and uniform hash distributions, the probability of this
381 <     * occurring at threshold is around 13%, meaning that only about 1
382 <     * in 8 puts check threshold (and after resizing, many fewer do
383 <     * so). But this approximation has high variance for small table
384 <     * sizes, so we check on any collision for sizes <= 64.  Further,
385 <     * to increase the probablity that a resize occurs soon enough, we
386 <     * offset the threshold (see THRESHOLD_OFFSET) by the expected
387 <     * number of puts between checks. This is currently set to 8, in
388 <     * accord with the default load factor. In practice, this is
389 <     * rarely overridden, and in any case is close enough to other
390 <     * plausible values not to waste dynamic probablity computation
391 <     * for more precision.
310 >     * first insertion.  Each bin in the table normally contains a
311 >     * list of Nodes (most often, the list has only zero or one Node).
312 >     * Table accesses require volatile/atomic reads, writes, and
313 >     * CASes.  Because there is no other way to arrange this without
314 >     * adding further indirections, we use intrinsics
315 >     * (sun.misc.Unsafe) operations.  The lists of nodes within bins
316 >     * are always accurately traversable under volatile reads, so long
317 >     * as lookups check hash code and non-nullness of value before
318 >     * checking key equality.
319 >     *
320 >     * We use the top (sign) bit of Node hash fields for control
321 >     * purposes -- it is available anyway because of addressing
322 >     * constraints.  Nodes with negative hash fields are forwarding
323 >     * nodes to either TreeBins or resized tables.  The lower 31 bits
324 >     * of each normal Node's hash field contain a transformation of
325 >     * the key's hash code.
326 >     *
327 >     * Insertion (via put or its variants) of the first node in an
328 >     * empty bin is performed by just CASing it to the bin.  This is
329 >     * by far the most common case for put operations under most
330 >     * key/hash distributions.  Other update operations (insert,
331 >     * delete, and replace) require locks.  We do not want to waste
332 >     * the space required to associate a distinct lock object with
333 >     * each bin, so instead use the first node of a bin list itself as
334 >     * a lock. Locking support for these locks relies on builtin
335 >     * "synchronized" monitors.
336 >     *
337 >     * Using the first node of a list as a lock does not by itself
338 >     * suffice though: When a node is locked, any update must first
339 >     * validate that it is still the first node after locking it, and
340 >     * retry if not. Because new nodes are always appended to lists,
341 >     * once a node is first in a bin, it remains first until deleted
342 >     * or the bin becomes invalidated (upon resizing).  However,
343 >     * operations that only conditionally update may inspect nodes
344 >     * until the point of update. This is a converse of sorts to the
345 >     * lazy locking technique described by Herlihy & Shavit.
346 >     *
347 >     * The main disadvantage of per-bin locks is that other update
348 >     * operations on other nodes in a bin list protected by the same
349 >     * lock can stall, for example when user equals() or mapping
350 >     * functions take a long time.  However, statistically, under
351 >     * random hash codes, this is not a common problem.  Ideally, the
352 >     * frequency of nodes in bins follows a Poisson distribution
353 >     * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
354 >     * parameter of about 0.5 on average, given the resizing threshold
355 >     * of 0.75, although with a large variance because of resizing
356 >     * granularity. Ignoring variance, the expected occurrences of
357 >     * list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
358 >     * first values are:
359 >     *
360 >     * 0:    0.60653066
361 >     * 1:    0.30326533
362 >     * 2:    0.07581633
363 >     * 3:    0.01263606
364 >     * 4:    0.00157952
365 >     * 5:    0.00015795
366 >     * 6:    0.00001316
367 >     * 7:    0.00000094
368 >     * 8:    0.00000006
369 >     * more: less than 1 in ten million
370 >     *
371 >     * Lock contention probability for two threads accessing distinct
372 >     * elements is roughly 1 / (8 * #elements) under random hashes.
373 >     *
374 >     * Actual hash code distributions encountered in practice
375 >     * sometimes deviate significantly from uniform randomness.  This
376 >     * includes the case when N > (1<<30), so some keys MUST collide.
377 >     * Similarly for dumb or hostile usages in which multiple keys are
378 >     * designed to have identical hash codes. Also, although we guard
379 >     * against the worst effects of this (see method spread), sets of
380 >     * hashes may differ only in bits that do not impact their bin
381 >     * index for a given power-of-two mask.  So we use a secondary
382 >     * strategy that applies when the number of nodes in a bin exceeds
383 >     * a threshold, and at least one of the keys implements
384 >     * Comparable.  These TreeBins use a balanced tree to hold nodes
385 >     * (a specialized form of red-black trees), bounding search time
386 >     * to O(log N).  Each search step in a TreeBin is around twice as
387 >     * slow as in a regular list, but given that N cannot exceed
388 >     * (1<<64) (before running out of addresses) this bounds search
389 >     * steps, lock hold times, etc, to reasonable constants (roughly
390 >     * 100 nodes inspected per operation worst case) so long as keys
391 >     * are Comparable (which is very common -- String, Long, etc).
392 >     * TreeBin nodes (TreeNodes) also maintain the same "next"
393 >     * traversal pointers as regular nodes, so can be traversed in
394 >     * iterators in the same way.
395 >     *
396 >     * The table is resized when occupancy exceeds a percentage
397 >     * threshold (nominally, 0.75, but see below).  Any thread
398 >     * noticing an overfull bin may assist in resizing after the
399 >     * initiating thread allocates and sets up the replacement
400 >     * array. However, rather than stalling, these other threads may
401 >     * proceed with insertions etc.  The use of TreeBins shields us
402 >     * from the worst case effects of overfilling while resizes are in
403 >     * progress.  Resizing proceeds by transferring bins, one by one,
404 >     * from the table to the next table. To enable concurrency, the
405 >     * next table must be (incrementally) prefilled with place-holders
406 >     * serving as reverse forwarders to the old table.  Because we are
407 >     * using power-of-two expansion, the elements from each bin must
408 >     * either stay at same index, or move with a power of two
409 >     * offset. We eliminate unnecessary node creation by catching
410 >     * cases where old nodes can be reused because their next fields
411 >     * won't change.  On average, only about one-sixth of them need
412 >     * cloning when a table doubles. The nodes they replace will be
413 >     * garbage collectable as soon as they are no longer referenced by
414 >     * any reader thread that may be in the midst of concurrently
415 >     * traversing table.  Upon transfer, the old table bin contains
416 >     * only a special forwarding node (with hash field "MOVED") that
417 >     * contains the next table as its key. On encountering a
418 >     * forwarding node, access and update operations restart, using
419 >     * the new table.
420 >     *
421 >     * Each bin transfer requires its bin lock, which can stall
422 >     * waiting for locks while resizing. However, because other
423 >     * threads can join in and help resize rather than contend for
424 >     * locks, average aggregate waits become shorter as resizing
425 >     * progresses.  The transfer operation must also ensure that all
426 >     * accessible bins in both the old and new table are usable by any
427 >     * traversal.  This is arranged by proceeding from the last bin
428 >     * (table.length - 1) up towards the first.  Upon seeing a
429 >     * forwarding node, traversals (see class Traverser) arrange to
430 >     * move to the new table without revisiting nodes.  However, to
431 >     * ensure that no intervening nodes are skipped, bin splitting can
432 >     * only begin after the associated reverse-forwarders are in
433 >     * place.
434 >     *
435 >     * The traversal scheme also applies to partial traversals of
436 >     * ranges of bins (via an alternate Traverser constructor)
437 >     * to support partitioned aggregate operations.  Also, read-only
438 >     * operations give up if ever forwarded to a null table, which
439 >     * provides support for shutdown-style clearing, which is also not
440 >     * currently implemented.
441 >     *
442 >     * Lazy table initialization minimizes footprint until first use,
443 >     * and also avoids resizings when the first operation is from a
444 >     * putAll, constructor with map argument, or deserialization.
445 >     * These cases attempt to override the initial capacity settings,
446 >     * but harmlessly fail to take effect in cases of races.
447 >     *
448 >     * The element count is maintained using a specialization of
449 >     * LongAdder. We need to incorporate a specialization rather than
450 >     * just use a LongAdder in order to access implicit
451 >     * contention-sensing that leads to creation of multiple
452 >     * CounterCells.  The counter mechanics avoid contention on
453 >     * updates but can encounter cache thrashing if read too
454 >     * frequently during concurrent access. To avoid reading so often,
455 >     * resizing under contention is attempted only upon adding to a
456 >     * bin already holding two or more nodes. Under uniform hash
457 >     * distributions, the probability of this occurring at threshold
458 >     * is around 13%, meaning that only about 1 in 8 puts check
459 >     * threshold (and after resizing, many fewer do so). The bulk
460 >     * putAll operation further reduces contention by only committing
461 >     * count updates upon these size checks.
462 >     *
463 >     * Maintaining API and serialization compatibility with previous
464 >     * versions of this class introduces several oddities. Mainly: We
465 >     * leave untouched but unused constructor arguments refering to
466 >     * concurrencyLevel. We accept a loadFactor constructor argument,
467 >     * but apply it only to initial table capacity (which is the only
468 >     * time that we can guarantee to honor it.) We also declare an
469 >     * unused "Segment" class that is instantiated in minimal form
470 >     * only when serializing.
471       */
472  
473      /* ---------------- Constants -------------- */
474  
475      /**
476 <     * The smallest allowed table capacity.  Must be a power of 2, at
477 <     * least 2.
476 >     * The largest possible table capacity.  This value must be
477 >     * exactly 1<<30 to stay within Java array allocation and indexing
478 >     * bounds for power of two table sizes, and is further required
479 >     * because the top two bits of 32bit hash fields are used for
480 >     * control purposes.
481       */
482 <    static final int MINIMUM_CAPACITY = 2;
482 >    private static final int MAXIMUM_CAPACITY = 1 << 30;
483  
484      /**
485 <     * The largest allowed table capacity.  Must be a power of 2, at
486 <     * most 1<<30.
485 >     * The default initial table capacity.  Must be a power of 2
486 >     * (i.e., at least 1) and at most MAXIMUM_CAPACITY.
487       */
488 <    static final int MAXIMUM_CAPACITY = 1 << 30;
488 >    private static final int DEFAULT_CAPACITY = 16;
489  
490      /**
491 <     * The default initial table capacity.  Must be a power of 2, at
492 <     * least MINIMUM_CAPACITY and at most MAXIMUM_CAPACITY
491 >     * The largest possible (non-power of two) array size.
492 >     * Needed by toArray and related methods.
493       */
494 <    static final int DEFAULT_CAPACITY = 16;
494 >    static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
495  
496      /**
497 <     * The default load factor for this table, used when not otherwise
498 <     * specified in a constructor.
497 >     * The default concurrency level for this table. Unused but
498 >     * defined for compatibility with previous versions of this class.
499       */
500 <    static final float DEFAULT_LOAD_FACTOR = 0.75f;
500 >    private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
501  
502      /**
503 <     * The default concurrency level for this table. Unused, but
504 <     * defined for compatibility with previous versions of this class.
503 >     * The load factor for this table. Overrides of this value in
504 >     * constructors affect only the initial table capacity.  The
505 >     * actual floating point value isn't normally used -- it is
506 >     * simpler to use expressions such as {@code n - (n >>> 2)} for
507 >     * the associated resizing threshold.
508 >     */
509 >    private static final float LOAD_FACTOR = 0.75f;
510 >
511 >    /**
512 >     * The bin count threshold for using a tree rather than list for a
513 >     * bin.  The value reflects the approximate break-even point for
514 >     * using tree-based operations.
515       */
516 <    static final int DEFAULT_CONCURRENCY_LEVEL = 16;
516 >    private static final int TREE_THRESHOLD = 8;
517  
518      /**
519 <     * The count value to offset thesholds to compensate for checking
520 <     * for resizing only when inserting into bins with two or more
521 <     * elements. See above for explanation.
519 >     * Minimum number of rebinnings per transfer step. Ranges are
520 >     * subdivided to allow multiple resizer threads.  This value
521 >     * serves as a lower bound to avoid resizers encountering
522 >     * excessive memory contention.  The value should be at least
523 >     * DEFAULT_CAPACITY.
524       */
525 <    static final int THRESHOLD_OFFSET = 8;
525 >    private static final int MIN_TRANSFER_STRIDE = 16;
526 >
527 >    /*
528 >     * Encodings for Node hash fields. See above for explanation.
529 >     */
530 >    static final int MOVED     = 0x80000000; // hash field for forwarding nodes
531 >    static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
532 >
533 >    /** Number of CPUS, to place bounds on some sizings */
534 >    static final int NCPU = Runtime.getRuntime().availableProcessors();
535 >
536 >    /* ---------------- Counters -------------- */
537 >
538 >    // Adapted from LongAdder and Striped64.
539 >    // See their internal docs for explanation.
540 >
541 >    // A padded cell for distributing counts
542 >    static final class CounterCell {
543 >        volatile long p0, p1, p2, p3, p4, p5, p6;
544 >        volatile long value;
545 >        volatile long q0, q1, q2, q3, q4, q5, q6;
546 >        CounterCell(long x) { value = x; }
547 >    }
548 >
549 >    /**
550 >     * Holder for the thread-local hash code determining which
551 >     * CounterCell to use. The code is initialized via the
552 >     * counterHashCodeGenerator, but may be moved upon collisions.
553 >     */
554 >    static final class CounterHashCode {
555 >        int code;
556 >    }
557  
558      /**
559 <     * Special node hash value indicating to use table in node.key
245 <     * Must be negative.
559 >     * Generates initial value for per-thread CounterHashCodes
560       */
561 <    static final int MOVED = -1;
561 >    static final AtomicInteger counterHashCodeGenerator = new AtomicInteger();
562 >
563 >    /**
564 >     * Increment for counterHashCodeGenerator. See class ThreadLocal
565 >     * for explanation.
566 >     */
567 >    static final int SEED_INCREMENT = 0x61c88647;
568 >
569 >    /**
570 >     * Per-thread counter hash codes. Shared across all instances.
571 >     */
572 >    static final ThreadLocal<CounterHashCode> threadCounterHashCode =
573 >        new ThreadLocal<CounterHashCode>();
574  
575      /* ---------------- Fields -------------- */
576  
577      /**
578       * The array of bins. Lazily initialized upon first insertion.
579 <     * Size is always a power of two. Accessed directly by inner
254 <     * classes.
579 >     * Size is always a power of two. Accessed directly by iterators.
580       */
581 <    transient volatile Node[] table;
581 >    transient volatile Node<V>[] table;
582  
583 <    /** The counter maintaining number of elements. */
584 <    private transient final LongAdder counter;
585 <    /** Nonzero when table is being initialized or resized. Updated via CAS. */
586 <    private transient volatile int resizing;
262 <    /** The target load factor for the table. */
263 <    private transient float loadFactor;
264 <    /** The next element count value upon which to resize the table. */
265 <    private transient int threshold;
266 <    /** The initial capacity of the table. */
267 <    private transient int initCap;
583 >    /**
584 >     * The next table to use; non-null only while resizing.
585 >     */
586 >    private transient volatile Node<V>[] nextTable;
587  
588 <    // views
589 <    transient Set<K> keySet;
590 <    transient Set<Map.Entry<K,V>> entrySet;
591 <    transient Collection<V> values;
592 <
593 <    /** For serialization compatability. Null unless serialized; see below */
275 <    Segment<K,V>[] segments;
588 >    /**
589 >     * Base counter value, used mainly when there is no contention,
590 >     * but also as a fallback during table initialization
591 >     * races. Updated via CAS.
592 >     */
593 >    private transient volatile long baseCount;
594  
595      /**
596 <     * Applies a supplemental hash function to a given hashCode, which
597 <     * defends against poor quality hash functions.  The result must
598 <     * be non-negative, and for reasonable performance must have good
599 <     * avalanche properties; i.e., that each bit of the argument
600 <     * affects each bit (except sign bit) of the result.
596 >     * Table initialization and resizing control.  When negative, the
597 >     * table is being initialized or resized: -1 for initialization,
598 >     * else -(1 + the number of active resizing threads).  Otherwise,
599 >     * when table is null, holds the initial table size to use upon
600 >     * creation, or 0 for default. After initialization, holds the
601 >     * next element count value upon which to resize the table.
602       */
603 <    private static final int spread(int h) {
604 <        // Apply base step of MurmurHash; see http://code.google.com/p/smhasher/
605 <        h ^= h >>> 16;
606 <        h *= 0x85ebca6b;
607 <        h ^= h >>> 13;
608 <        h *= 0xc2b2ae35;
609 <        return (h >>> 16) ^ (h & 0x7fffffff); // mask out sign bit
603 >    private transient volatile int sizeCtl;
604 >
605 >    /**
606 >     * The next table index (plus one) to split while resizing.
607 >     */
608 >    private transient volatile int transferIndex;
609 >
610 >    /**
611 >     * The least available table index to split while resizing.
612 >     */
613 >    private transient volatile int transferOrigin;
614 >
615 >    /**
616 >     * Spinlock (locked via CAS) used when resizing and/or creating Cells.
617 >     */
618 >    private transient volatile int counterBusy;
619 >
620 >    /**
621 >     * Table of counter cells. When non-null, size is a power of 2.
622 >     */
623 >    private transient volatile CounterCell[] counterCells;
624 >
625 >    // views
626 >    private transient KeySetView<K,V> keySet;
627 >    private transient ValuesView<K,V> values;
628 >    private transient EntrySetView<K,V> entrySet;
629 >
630 >    /** For serialization compatibility. Null unless serialized; see below */
631 >    private Segment<K,V>[] segments;
632 >
633 >    /* ---------------- Table element access -------------- */
634 >
635 >    /*
636 >     * Volatile access methods are used for table elements as well as
637 >     * elements of in-progress next table while resizing.  Uses are
638 >     * null checked by callers, and implicitly bounds-checked, relying
639 >     * on the invariants that tab arrays have non-zero size, and all
640 >     * indices are masked with (tab.length - 1) which is never
641 >     * negative and always less than length. Note that, to be correct
642 >     * wrt arbitrary concurrency errors by users, bounds checks must
643 >     * operate on local variables, which accounts for some odd-looking
644 >     * inline assignments below.
645 >     */
646 >
647 >    @SuppressWarnings("unchecked") static final <V> Node<V> tabAt
648 >        (Node<V>[] tab, int i) { // used by Traverser
649 >        return (Node<V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
650 >    }
651 >
652 >    private static final <V> boolean casTabAt
653 >        (Node<V>[] tab, int i, Node<V> c, Node<V> v) {
654 >        return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
655 >    }
656 >
657 >    private static final <V> void setTabAt
658 >        (Node<V>[] tab, int i, Node<V> v) {
659 >        U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
660      }
661  
662 +    /* ---------------- Nodes -------------- */
663 +
664      /**
665       * Key-value entry. Note that this is never exported out as a
666 <     * user-visible Map.Entry.
666 >     * user-visible Map.Entry (see MapEntry below). Nodes with a hash
667 >     * field of MOVED are special, and do not contain user keys or
668 >     * values.  Otherwise, keys are never null, and null val fields
669 >     * indicate that a node is in the process of being deleted or
670 >     * created. For purposes of read-only access, a key may be read
671 >     * before a val, but can only be used after checking val to be
672 >     * non-null.
673       */
674 <    static final class Node {
674 >    static class Node<V> {
675          final int hash;
676          final Object key;
677 <        volatile Object val;
678 <        volatile Node next;
677 >        volatile V val;
678 >        volatile Node<V> next;
679  
680 <        Node(int hash, Object key, Object val, Node next) {
680 >        Node(int hash, Object key, V val, Node<V> next) {
681              this.hash = hash;
682              this.key = key;
683              this.val = val;
# Line 308 | Line 685 | public class ConcurrentHashMapV8<K, V>
685          }
686      }
687  
688 <    /*
312 <     * Volatile access nethods are used for table elements as well as
313 <     * elements of in-progress next table while resizing.  Uses in
314 <     * access and update methods are null checked by callers, and
315 <     * implicitly bounds-checked, relying on the invariants that tab
316 <     * arrays have non-zero size, and all indices are masked with
317 <     * (tab.length - 1) which is never negative and always less than
318 <     * length. The "relaxed" non-volatile forms are used only during
319 <     * table initialization. The only other usage is in
320 <     * HashIterator.advance, which performs explicit checks.
321 <     */
688 >    /* ---------------- TreeBins -------------- */
689  
690 <    static final Node tabAt(Node[] tab, int i) { // used in HashIterator
691 <        return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE);
690 >    /**
691 >     * Nodes for use in TreeBins
692 >     */
693 >    static final class TreeNode<V> extends Node<V> {
694 >        TreeNode<V> parent;  // red-black tree links
695 >        TreeNode<V> left;
696 >        TreeNode<V> right;
697 >        TreeNode<V> prev;    // needed to unlink next upon deletion
698 >        boolean red;
699 >
700 >        TreeNode(int hash, Object key, V val, Node<V> next, TreeNode<V> parent) {
701 >            super(hash, key, val, next);
702 >            this.parent = parent;
703 >        }
704      }
705  
706 <    private static final boolean casTabAt(Node[] tab, int i, Node c, Node v) {
707 <        return UNSAFE.compareAndSwapObject(tab, ((long)i<<ASHIFT)+ABASE, c, v);
708 <    }
706 >    /**
707 >     * A specialized form of red-black tree for use in bins
708 >     * whose size exceeds a threshold.
709 >     *
710 >     * TreeBins use a special form of comparison for search and
711 >     * related operations (which is the main reason we cannot use
712 >     * existing collections such as TreeMaps). TreeBins contain
713 >     * Comparable elements, but may contain others, as well as
714 >     * elements that are Comparable but not necessarily Comparable<T>
715 >     * for the same T, so we cannot invoke compareTo among them. To
716 >     * handle this, the tree is ordered primarily by hash value, then
717 >     * by getClass().getName() order, and then by Comparator order
718 >     * among elements of the same class.  On lookup at a node, if
719 >     * elements are not comparable or compare as 0, both left and
720 >     * right children may need to be searched in the case of tied hash
721 >     * values. (This corresponds to the full list search that would be
722 >     * necessary if all elements were non-Comparable and had tied
723 >     * hashes.)  The red-black balancing code is updated from
724 >     * pre-jdk-collections
725 >     * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
726 >     * based in turn on Cormen, Leiserson, and Rivest "Introduction to
727 >     * Algorithms" (CLR).
728 >     *
729 >     * TreeBins also maintain a separate locking discipline than
730 >     * regular bins. Because they are forwarded via special MOVED
731 >     * nodes at bin heads (which can never change once established),
732 >     * we cannot use those nodes as locks. Instead, TreeBin
733 >     * extends AbstractQueuedSynchronizer to support a simple form of
734 >     * read-write lock. For update operations and table validation,
735 >     * the exclusive form of lock behaves in the same way as bin-head
736 >     * locks. However, lookups use shared read-lock mechanics to allow
737 >     * multiple readers in the absence of writers.  Additionally,
738 >     * these lookups do not ever block: While the lock is not
739 >     * available, they proceed along the slow traversal path (via
740 >     * next-pointers) until the lock becomes available or the list is
741 >     * exhausted, whichever comes first. (These cases are not fast,
742 >     * but maximize aggregate expected throughput.)  The AQS mechanics
743 >     * for doing this are straightforward.  The lock state is held as
744 >     * AQS getState().  Read counts are negative; the write count (1)
745 >     * is positive.  There are no signalling preferences among readers
746 >     * and writers. Since we don't need to export full Lock API, we
747 >     * just override the minimal AQS methods and use them directly.
748 >     */
749 >    static final class TreeBin<V> extends AbstractQueuedSynchronizer {
750 >        private static final long serialVersionUID = 2249069246763182397L;
751 >        transient TreeNode<V> root;  // root of tree
752 >        transient TreeNode<V> first; // head of next-pointer list
753  
754 <    private static final void setTabAt(Node[] tab, int i, Node v) {
755 <        UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v);
756 <    }
754 >        /* AQS overrides */
755 >        public final boolean isHeldExclusively() { return getState() > 0; }
756 >        public final boolean tryAcquire(int ignore) {
757 >            if (compareAndSetState(0, 1)) {
758 >                setExclusiveOwnerThread(Thread.currentThread());
759 >                return true;
760 >            }
761 >            return false;
762 >        }
763 >        public final boolean tryRelease(int ignore) {
764 >            setExclusiveOwnerThread(null);
765 >            setState(0);
766 >            return true;
767 >        }
768 >        public final int tryAcquireShared(int ignore) {
769 >            for (int c;;) {
770 >                if ((c = getState()) > 0)
771 >                    return -1;
772 >                if (compareAndSetState(c, c -1))
773 >                    return 1;
774 >            }
775 >        }
776 >        public final boolean tryReleaseShared(int ignore) {
777 >            int c;
778 >            do {} while (!compareAndSetState(c = getState(), c + 1));
779 >            return c == -1;
780 >        }
781 >
782 >        /** From CLR */
783 >        private void rotateLeft(TreeNode<V> p) {
784 >            if (p != null) {
785 >                TreeNode<V> r = p.right, pp, rl;
786 >                if ((rl = p.right = r.left) != null)
787 >                    rl.parent = p;
788 >                if ((pp = r.parent = p.parent) == null)
789 >                    root = r;
790 >                else if (pp.left == p)
791 >                    pp.left = r;
792 >                else
793 >                    pp.right = r;
794 >                r.left = p;
795 >                p.parent = r;
796 >            }
797 >        }
798  
799 <    private static final Node relaxedTabAt(Node[] tab, int i) {
800 <        return (Node)UNSAFE.getObject(tab, ((long)i<<ASHIFT)+ABASE);
801 <    }
799 >        /** From CLR */
800 >        private void rotateRight(TreeNode<V> p) {
801 >            if (p != null) {
802 >                TreeNode<V> l = p.left, pp, lr;
803 >                if ((lr = p.left = l.right) != null)
804 >                    lr.parent = p;
805 >                if ((pp = l.parent = p.parent) == null)
806 >                    root = l;
807 >                else if (pp.right == p)
808 >                    pp.right = l;
809 >                else
810 >                    pp.left = l;
811 >                l.right = p;
812 >                p.parent = l;
813 >            }
814 >        }
815  
816 <    private static final void relaxedSetTabAt(Node[] tab, int i, Node v) {
817 <        UNSAFE.putObject(tab, ((long)i<<ASHIFT)+ABASE, v);
818 <    }
816 >        /**
817 >         * Returns the TreeNode (or null if not found) for the given key
818 >         * starting at given root.
819 >         */
820 >        @SuppressWarnings("unchecked") final TreeNode<V> getTreeNode
821 >            (int h, Object k, TreeNode<V> p) {
822 >            Class<?> c = k.getClass();
823 >            while (p != null) {
824 >                int dir, ph;  Object pk; Class<?> pc;
825 >                if ((ph = p.hash) == h) {
826 >                    if ((pk = p.key) == k || k.equals(pk))
827 >                        return p;
828 >                    if (c != (pc = pk.getClass()) ||
829 >                        !(k instanceof Comparable) ||
830 >                        (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
831 >                        if ((dir = (c == pc) ? 0 :
832 >                             c.getName().compareTo(pc.getName())) == 0) {
833 >                            TreeNode<V> r = null, pl, pr; // check both sides
834 >                            if ((pr = p.right) != null && h >= pr.hash &&
835 >                                (r = getTreeNode(h, k, pr)) != null)
836 >                                return r;
837 >                            else if ((pl = p.left) != null && h <= pl.hash)
838 >                                dir = -1;
839 >                            else // nothing there
840 >                                return null;
841 >                        }
842 >                    }
843 >                }
844 >                else
845 >                    dir = (h < ph) ? -1 : 1;
846 >                p = (dir > 0) ? p.right : p.left;
847 >            }
848 >            return null;
849 >        }
850  
851 <    /* ---------------- Access and update operations -------------- */
851 >        /**
852 >         * Wrapper for getTreeNode used by CHM.get. Tries to obtain
853 >         * read-lock to call getTreeNode, but during failure to get
854 >         * lock, searches along next links.
855 >         */
856 >        final V getValue(int h, Object k) {
857 >            Node<V> r = null;
858 >            int c = getState(); // Must read lock state first
859 >            for (Node<V> e = first; e != null; e = e.next) {
860 >                if (c <= 0 && compareAndSetState(c, c - 1)) {
861 >                    try {
862 >                        r = getTreeNode(h, k, root);
863 >                    } finally {
864 >                        releaseShared(0);
865 >                    }
866 >                    break;
867 >                }
868 >                else if (e.hash == h && k.equals(e.key)) {
869 >                    r = e;
870 >                    break;
871 >                }
872 >                else
873 >                    c = getState();
874 >            }
875 >            return r == null ? null : r.val;
876 >        }
877  
878 <    /** Implementation for get and containsKey **/
879 <    private final Object internalGet(Object k) {
880 <        int h = spread(k.hashCode());
881 <        Node[] tab = table;
882 <        retry: while (tab != null) {
883 <            Node e = tabAt(tab, (tab.length - 1) & h);
884 <            while (e != null) {
885 <                int eh = e.hash;
886 <                if (eh == h) {
887 <                    Object ek = e.key, ev = e.val;
888 <                    if (ev != null && ek != null && (k == ek || k.equals(ek)))
889 <                        return ev;
878 >        /**
879 >         * Finds or adds a node.
880 >         * @return null if added
881 >         */
882 >        @SuppressWarnings("unchecked") final TreeNode<V> putTreeNode
883 >            (int h, Object k, V v) {
884 >            Class<?> c = k.getClass();
885 >            TreeNode<V> pp = root, p = null;
886 >            int dir = 0;
887 >            while (pp != null) { // find existing node or leaf to insert at
888 >                int ph;  Object pk; Class<?> pc;
889 >                p = pp;
890 >                if ((ph = p.hash) == h) {
891 >                    if ((pk = p.key) == k || k.equals(pk))
892 >                        return p;
893 >                    if (c != (pc = pk.getClass()) ||
894 >                        !(k instanceof Comparable) ||
895 >                        (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) {
896 >                        TreeNode<V> s = null, r = null, pr;
897 >                        if ((dir = (c == pc) ? 0 :
898 >                             c.getName().compareTo(pc.getName())) == 0) {
899 >                            if ((pr = p.right) != null && h >= pr.hash &&
900 >                                (r = getTreeNode(h, k, pr)) != null)
901 >                                return r;
902 >                            else // continue left
903 >                                dir = -1;
904 >                        }
905 >                        else if ((pr = p.right) != null && h >= pr.hash)
906 >                            s = pr;
907 >                        if (s != null && (r = getTreeNode(h, k, s)) != null)
908 >                            return r;
909 >                    }
910                  }
911 <                else if (eh < 0) { // bin was moved during resize
912 <                    tab = (Node[])e.key;
913 <                    continue retry;
911 >                else
912 >                    dir = (h < ph) ? -1 : 1;
913 >                pp = (dir > 0) ? p.right : p.left;
914 >            }
915 >
916 >            TreeNode<V> f = first;
917 >            TreeNode<V> x = first = new TreeNode<V>(h, k, v, f, p);
918 >            if (p == null)
919 >                root = x;
920 >            else { // attach and rebalance; adapted from CLR
921 >                TreeNode<V> xp, xpp;
922 >                if (f != null)
923 >                    f.prev = x;
924 >                if (dir <= 0)
925 >                    p.left = x;
926 >                else
927 >                    p.right = x;
928 >                x.red = true;
929 >                while (x != null && (xp = x.parent) != null && xp.red &&
930 >                       (xpp = xp.parent) != null) {
931 >                    TreeNode<V> xppl = xpp.left;
932 >                    if (xp == xppl) {
933 >                        TreeNode<V> y = xpp.right;
934 >                        if (y != null && y.red) {
935 >                            y.red = false;
936 >                            xp.red = false;
937 >                            xpp.red = true;
938 >                            x = xpp;
939 >                        }
940 >                        else {
941 >                            if (x == xp.right) {
942 >                                rotateLeft(x = xp);
943 >                                xpp = (xp = x.parent) == null ? null : xp.parent;
944 >                            }
945 >                            if (xp != null) {
946 >                                xp.red = false;
947 >                                if (xpp != null) {
948 >                                    xpp.red = true;
949 >                                    rotateRight(xpp);
950 >                                }
951 >                            }
952 >                        }
953 >                    }
954 >                    else {
955 >                        TreeNode<V> y = xppl;
956 >                        if (y != null && y.red) {
957 >                            y.red = false;
958 >                            xp.red = false;
959 >                            xpp.red = true;
960 >                            x = xpp;
961 >                        }
962 >                        else {
963 >                            if (x == xp.left) {
964 >                                rotateRight(x = xp);
965 >                                xpp = (xp = x.parent) == null ? null : xp.parent;
966 >                            }
967 >                            if (xp != null) {
968 >                                xp.red = false;
969 >                                if (xpp != null) {
970 >                                    xpp.red = true;
971 >                                    rotateLeft(xpp);
972 >                                }
973 >                            }
974 >                        }
975 >                    }
976                  }
977 <                e = e.next;
977 >                TreeNode<V> r = root;
978 >                if (r != null && r.red)
979 >                    r.red = false;
980              }
981 <            break;
981 >            return null;
982          }
366        return null;
367    }
983  
984 <    /** Implementation for put and putIfAbsent **/
985 <    private final Object internalPut(Object k, Object v, boolean replace) {
986 <        int h = spread(k.hashCode());
987 <        Object oldVal = null;  // the previous value or null if none
988 <        Node[] tab = table;
989 <        for (;;) {
990 <            Node e; int i;
991 <            if (tab == null)
992 <                tab = grow(0);
993 <            else if ((e = tabAt(tab, i = (tab.length - 1) & h)) == null) {
994 <                if (casTabAt(tab, i, null, new Node(h, k, v, null)))
995 <                    break;
984 >        /**
985 >         * Removes the given node, that must be present before this
986 >         * call.  This is messier than typical red-black deletion code
987 >         * because we cannot swap the contents of an interior node
988 >         * with a leaf successor that is pinned by "next" pointers
989 >         * that are accessible independently of lock. So instead we
990 >         * swap the tree linkages.
991 >         */
992 >        final void deleteTreeNode(TreeNode<V> p) {
993 >            TreeNode<V> next = (TreeNode<V>)p.next; // unlink traversal pointers
994 >            TreeNode<V> pred = p.prev;
995 >            if (pred == null)
996 >                first = next;
997 >            else
998 >                pred.next = next;
999 >            if (next != null)
1000 >                next.prev = pred;
1001 >            TreeNode<V> replacement;
1002 >            TreeNode<V> pl = p.left;
1003 >            TreeNode<V> pr = p.right;
1004 >            if (pl != null && pr != null) {
1005 >                TreeNode<V> s = pr, sl;
1006 >                while ((sl = s.left) != null) // find successor
1007 >                    s = sl;
1008 >                boolean c = s.red; s.red = p.red; p.red = c; // swap colors
1009 >                TreeNode<V> sr = s.right;
1010 >                TreeNode<V> pp = p.parent;
1011 >                if (s == pr) { // p was s's direct parent
1012 >                    p.parent = s;
1013 >                    s.right = p;
1014 >                }
1015 >                else {
1016 >                    TreeNode<V> sp = s.parent;
1017 >                    if ((p.parent = sp) != null) {
1018 >                        if (s == sp.left)
1019 >                            sp.left = p;
1020 >                        else
1021 >                            sp.right = p;
1022 >                    }
1023 >                    if ((s.right = pr) != null)
1024 >                        pr.parent = s;
1025 >                }
1026 >                p.left = null;
1027 >                if ((p.right = sr) != null)
1028 >                    sr.parent = p;
1029 >                if ((s.left = pl) != null)
1030 >                    pl.parent = s;
1031 >                if ((s.parent = pp) == null)
1032 >                    root = s;
1033 >                else if (p == pp.left)
1034 >                    pp.left = s;
1035 >                else
1036 >                    pp.right = s;
1037 >                replacement = sr;
1038 >            }
1039 >            else
1040 >                replacement = (pl != null) ? pl : pr;
1041 >            TreeNode<V> pp = p.parent;
1042 >            if (replacement == null) {
1043 >                if (pp == null) {
1044 >                    root = null;
1045 >                    return;
1046 >                }
1047 >                replacement = p;
1048              }
382            else if (e.hash < 0)
383                tab = (Node[])e.key;
1049              else {
1050 <                boolean validated = false;
1051 <                boolean checkSize = false;
1052 <                synchronized (e) {
1053 <                    Node first = e;
1054 <                    for (;;) {
1055 <                        Object ek, ev;
1056 <                        if ((ev = e.val) == null)
1057 <                            break;
1058 <                        if (e.hash == h && (ek = e.key) != null &&
1059 <                            (k == ek || k.equals(ek))) {
1060 <                            if (tabAt(tab, i) == first) {
1061 <                                validated = true;
1062 <                                oldVal = ev;
1063 <                                if (replace)
1064 <                                    e.val = v;
1050 >                replacement.parent = pp;
1051 >                if (pp == null)
1052 >                    root = replacement;
1053 >                else if (p == pp.left)
1054 >                    pp.left = replacement;
1055 >                else
1056 >                    pp.right = replacement;
1057 >                p.left = p.right = p.parent = null;
1058 >            }
1059 >            if (!p.red) { // rebalance, from CLR
1060 >                TreeNode<V> x = replacement;
1061 >                while (x != null) {
1062 >                    TreeNode<V> xp, xpl;
1063 >                    if (x.red || (xp = x.parent) == null) {
1064 >                        x.red = false;
1065 >                        break;
1066 >                    }
1067 >                    if (x == (xpl = xp.left)) {
1068 >                        TreeNode<V> sib = xp.right;
1069 >                        if (sib != null && sib.red) {
1070 >                            sib.red = false;
1071 >                            xp.red = true;
1072 >                            rotateLeft(xp);
1073 >                            sib = (xp = x.parent) == null ? null : xp.right;
1074 >                        }
1075 >                        if (sib == null)
1076 >                            x = xp;
1077 >                        else {
1078 >                            TreeNode<V> sl = sib.left, sr = sib.right;
1079 >                            if ((sr == null || !sr.red) &&
1080 >                                (sl == null || !sl.red)) {
1081 >                                sib.red = true;
1082 >                                x = xp;
1083                              }
1084 <                            break;
1084 >                            else {
1085 >                                if (sr == null || !sr.red) {
1086 >                                    if (sl != null)
1087 >                                        sl.red = false;
1088 >                                    sib.red = true;
1089 >                                    rotateRight(sib);
1090 >                                    sib = (xp = x.parent) == null ?
1091 >                                        null : xp.right;
1092 >                                }
1093 >                                if (sib != null) {
1094 >                                    sib.red = (xp == null) ? false : xp.red;
1095 >                                    if ((sr = sib.right) != null)
1096 >                                        sr.red = false;
1097 >                                }
1098 >                                if (xp != null) {
1099 >                                    xp.red = false;
1100 >                                    rotateLeft(xp);
1101 >                                }
1102 >                                x = root;
1103 >                            }
1104 >                        }
1105 >                    }
1106 >                    else { // symmetric
1107 >                        TreeNode<V> sib = xpl;
1108 >                        if (sib != null && sib.red) {
1109 >                            sib.red = false;
1110 >                            xp.red = true;
1111 >                            rotateRight(xp);
1112 >                            sib = (xp = x.parent) == null ? null : xp.left;
1113                          }
1114 <                        Node last = e;
1115 <                        if ((e = e.next) == null) {
1116 <                            if (tabAt(tab, i) == first) {
1117 <                                validated = true;
1118 <                                last.next = new Node(h, k, v, null);
1119 <                                if (last != first || tab.length <= 64)
1120 <                                    checkSize = true;
1114 >                        if (sib == null)
1115 >                            x = xp;
1116 >                        else {
1117 >                            TreeNode<V> sl = sib.left, sr = sib.right;
1118 >                            if ((sl == null || !sl.red) &&
1119 >                                (sr == null || !sr.red)) {
1120 >                                sib.red = true;
1121 >                                x = xp;
1122 >                            }
1123 >                            else {
1124 >                                if (sl == null || !sl.red) {
1125 >                                    if (sr != null)
1126 >                                        sr.red = false;
1127 >                                    sib.red = true;
1128 >                                    rotateLeft(sib);
1129 >                                    sib = (xp = x.parent) == null ?
1130 >                                        null : xp.left;
1131 >                                }
1132 >                                if (sib != null) {
1133 >                                    sib.red = (xp == null) ? false : xp.red;
1134 >                                    if ((sl = sib.left) != null)
1135 >                                        sl.red = false;
1136 >                                }
1137 >                                if (xp != null) {
1138 >                                    xp.red = false;
1139 >                                    rotateRight(xp);
1140 >                                }
1141 >                                x = root;
1142                              }
411                            break;
1143                          }
1144                      }
1145                  }
1146 <                if (validated) {
1147 <                    if (checkSize && tab.length < MAXIMUM_CAPACITY &&
1148 <                        resizing == 0 && counter.sum() >= threshold)
1149 <                        grow(0);
1150 <                    break;
1146 >            }
1147 >            if (p == replacement && (pp = p.parent) != null) {
1148 >                if (p == pp.left) // detach pointers
1149 >                    pp.left = null;
1150 >                else if (p == pp.right)
1151 >                    pp.right = null;
1152 >                p.parent = null;
1153 >            }
1154 >        }
1155 >    }
1156 >
1157 >    /* ---------------- Collision reduction methods -------------- */
1158 >
1159 >    /**
1160 >     * Spreads higher bits to lower, and also forces top bit to 0.
1161 >     * Because the table uses power-of-two masking, sets of hashes
1162 >     * that vary only in bits above the current mask will always
1163 >     * collide. (Among known examples are sets of Float keys holding
1164 >     * consecutive whole numbers in small tables.)  To counter this,
1165 >     * we apply a transform that spreads the impact of higher bits
1166 >     * downward. There is a tradeoff between speed, utility, and
1167 >     * quality of bit-spreading. Because many common sets of hashes
1168 >     * are already reasonably distributed across bits (so don't benefit
1169 >     * from spreading), and because we use trees to handle large sets
1170 >     * of collisions in bins, we don't need excessively high quality.
1171 >     */
1172 >    private static final int spread(int h) {
1173 >        h ^= (h >>> 18) ^ (h >>> 12);
1174 >        return (h ^ (h >>> 10)) & HASH_BITS;
1175 >    }
1176 >
1177 >    /**
1178 >     * Replaces a list bin with a tree bin if key is comparable.  Call
1179 >     * only when locked.
1180 >     */
1181 >    private final void replaceWithTreeBin(Node<V>[] tab, int index, Object key) {
1182 >        if (key instanceof Comparable) {
1183 >            TreeBin<V> t = new TreeBin<V>();
1184 >            for (Node<V> e = tabAt(tab, index); e != null; e = e.next)
1185 >                t.putTreeNode(e.hash, e.key, e.val);
1186 >            setTabAt(tab, index, new Node<V>(MOVED, t, null, null));
1187 >        }
1188 >    }
1189 >
1190 >    /* ---------------- Internal access and update methods -------------- */
1191 >
1192 >    /** Implementation for get and containsKey */
1193 >    @SuppressWarnings("unchecked") private final V internalGet(Object k) {
1194 >        int h = spread(k.hashCode());
1195 >        retry: for (Node<V>[] tab = table; tab != null;) {
1196 >            Node<V> e; Object ek; V ev; int eh; // locals to read fields once
1197 >            for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) {
1198 >                if ((eh = e.hash) < 0) {
1199 >                    if ((ek = e.key) instanceof TreeBin)  // search TreeBin
1200 >                        return ((TreeBin<V>)ek).getValue(h, k);
1201 >                    else {                      // restart with new table
1202 >                        tab = (Node<V>[])ek;
1203 >                        continue retry;
1204 >                    }
1205                  }
1206 +                else if (eh == h && (ev = e.val) != null &&
1207 +                         ((ek = e.key) == k || k.equals(ek)))
1208 +                    return ev;
1209              }
1210 +            break;
1211          }
1212 <        if (oldVal == null)
424 <            counter.increment();
425 <        return oldVal;
1212 >        return null;
1213      }
1214  
1215      /**
1216 <     * Covers the four public remove/replace methods: Replaces node
1217 <     * value with v, conditional upon match of cv if non-null.  If
1218 <     * resulting value is null, delete.
1216 >     * Implementation for the four public remove/replace methods:
1217 >     * Replaces node value with v, conditional upon match of cv if
1218 >     * non-null.  If resulting value is null, delete.
1219       */
1220 <    private final Object internalReplace(Object k, Object v, Object cv) {
1220 >    @SuppressWarnings("unchecked") private final V internalReplace
1221 >        (Object k, V v, Object cv) {
1222          int h = spread(k.hashCode());
1223 <        Object oldVal = null;
1224 <        Node e; int i;
1225 <        Node[] tab = table;
1226 <        while (tab != null &&
1227 <               (e = tabAt(tab, i = (tab.length - 1) & h)) != null) {
1228 <            if (e.hash < 0)
1229 <                tab = (Node[])e.key;
1223 >        V oldVal = null;
1224 >        for (Node<V>[] tab = table;;) {
1225 >            Node<V> f; int i, fh; Object fk;
1226 >            if (tab == null ||
1227 >                (f = tabAt(tab, i = (tab.length - 1) & h)) == null)
1228 >                break;
1229 >            else if ((fh = f.hash) < 0) {
1230 >                if ((fk = f.key) instanceof TreeBin) {
1231 >                    TreeBin<V> t = (TreeBin<V>)fk;
1232 >                    boolean validated = false;
1233 >                    boolean deleted = false;
1234 >                    t.acquire(0);
1235 >                    try {
1236 >                        if (tabAt(tab, i) == f) {
1237 >                            validated = true;
1238 >                            TreeNode<V> p = t.getTreeNode(h, k, t.root);
1239 >                            if (p != null) {
1240 >                                V pv = p.val;
1241 >                                if (cv == null || cv == pv || cv.equals(pv)) {
1242 >                                    oldVal = pv;
1243 >                                    if ((p.val = v) == null) {
1244 >                                        deleted = true;
1245 >                                        t.deleteTreeNode(p);
1246 >                                    }
1247 >                                }
1248 >                            }
1249 >                        }
1250 >                    } finally {
1251 >                        t.release(0);
1252 >                    }
1253 >                    if (validated) {
1254 >                        if (deleted)
1255 >                            addCount(-1L, -1);
1256 >                        break;
1257 >                    }
1258 >                }
1259 >                else
1260 >                    tab = (Node<V>[])fk;
1261 >            }
1262 >            else if (fh != h && f.next == null) // precheck
1263 >                break;                          // rules out possible existence
1264              else {
1265                  boolean validated = false;
1266                  boolean deleted = false;
1267 <                synchronized (e) {
1268 <                    Node pred = null;
1269 <                    Node first = e;
1270 <                    for (;;) {
1271 <                        Object ek, ev;
1272 <                        if ((ev = e.val) == null)
1273 <                            break;
1274 <                        if (e.hash == h && (ek = e.key) != null &&
453 <                            (k == ek || k.equals(ek))) {
454 <                            if (tabAt(tab, i) == first) {
455 <                                validated = true;
1267 >                synchronized (f) {
1268 >                    if (tabAt(tab, i) == f) {
1269 >                        validated = true;
1270 >                        for (Node<V> e = f, pred = null;;) {
1271 >                            Object ek; V ev;
1272 >                            if (e.hash == h &&
1273 >                                ((ev = e.val) != null) &&
1274 >                                ((ek = e.key) == k || k.equals(ek))) {
1275                                  if (cv == null || cv == ev || cv.equals(ev)) {
1276                                      oldVal = ev;
1277                                      if ((e.val = v) == null) {
1278                                          deleted = true;
1279 <                                        Node en = e.next;
1279 >                                        Node<V> en = e.next;
1280                                          if (pred != null)
1281                                              pred.next = en;
1282                                          else
1283                                              setTabAt(tab, i, en);
1284                                      }
1285                                  }
1286 +                                break;
1287                              }
1288 <                            break;
1289 <                        }
1290 <                        pred = e;
471 <                        if ((e = e.next) == null) {
472 <                            if (tabAt(tab, i) == first)
473 <                                validated = true;
474 <                            break;
1288 >                            pred = e;
1289 >                            if ((e = e.next) == null)
1290 >                                break;
1291                          }
1292                      }
1293                  }
1294                  if (validated) {
1295                      if (deleted)
1296 <                        counter.decrement();
1296 >                        addCount(-1L, -1);
1297                      break;
1298                  }
1299              }
# Line 485 | Line 1301 | public class ConcurrentHashMapV8<K, V>
1301          return oldVal;
1302      }
1303  
1304 <    /** Implementation for computeIfAbsent and compute */
1305 <    @SuppressWarnings("unchecked")
1306 <    private final V internalCompute(K k,
1307 <                                    MappingFunction<? super K, ? extends V> f,
1308 <                                    boolean replace) {
1304 >    /*
1305 >     * Internal versions of insertion methods
1306 >     * All have the same basic structure as the first (internalPut):
1307 >     *  1. If table uninitialized, create
1308 >     *  2. If bin empty, try to CAS new node
1309 >     *  3. If bin stale, use new table
1310 >     *  4. if bin converted to TreeBin, validate and relay to TreeBin methods
1311 >     *  5. Lock and validate; if valid, scan and add or update
1312 >     *
1313 >     * The putAll method differs mainly in attempting to pre-allocate
1314 >     * enough table space, and also more lazily performs count updates
1315 >     * and checks.
1316 >     *
1317 >     * Most of the function-accepting methods can't be factored nicely
1318 >     * because they require different functional forms, so instead
1319 >     * sprawl out similar mechanics.
1320 >     */
1321 >
1322 >    /** Implementation for put and putIfAbsent */
1323 >    @SuppressWarnings("unchecked") private final V internalPut
1324 >        (K k, V v, boolean onlyIfAbsent) {
1325 >        if (k == null || v == null) throw new NullPointerException();
1326 >        int h = spread(k.hashCode());
1327 >        int len = 0;
1328 >        for (Node<V>[] tab = table;;) {
1329 >            int i, fh; Node<V> f; Object fk; V fv;
1330 >            if (tab == null)
1331 >                tab = initTable();
1332 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1333 >                if (casTabAt(tab, i, null, new Node<V>(h, k, v, null)))
1334 >                    break;                   // no lock when adding to empty bin
1335 >            }
1336 >            else if ((fh = f.hash) < 0) {
1337 >                if ((fk = f.key) instanceof TreeBin) {
1338 >                    TreeBin<V> t = (TreeBin<V>)fk;
1339 >                    V oldVal = null;
1340 >                    t.acquire(0);
1341 >                    try {
1342 >                        if (tabAt(tab, i) == f) {
1343 >                            len = 2;
1344 >                            TreeNode<V> p = t.putTreeNode(h, k, v);
1345 >                            if (p != null) {
1346 >                                oldVal = p.val;
1347 >                                if (!onlyIfAbsent)
1348 >                                    p.val = v;
1349 >                            }
1350 >                        }
1351 >                    } finally {
1352 >                        t.release(0);
1353 >                    }
1354 >                    if (len != 0) {
1355 >                        if (oldVal != null)
1356 >                            return oldVal;
1357 >                        break;
1358 >                    }
1359 >                }
1360 >                else
1361 >                    tab = (Node<V>[])fk;
1362 >            }
1363 >            else if (onlyIfAbsent && fh == h && (fv = f.val) != null &&
1364 >                     ((fk = f.key) == k || k.equals(fk))) // peek while nearby
1365 >                return fv;
1366 >            else {
1367 >                V oldVal = null;
1368 >                synchronized (f) {
1369 >                    if (tabAt(tab, i) == f) {
1370 >                        len = 1;
1371 >                        for (Node<V> e = f;; ++len) {
1372 >                            Object ek; V ev;
1373 >                            if (e.hash == h &&
1374 >                                (ev = e.val) != null &&
1375 >                                ((ek = e.key) == k || k.equals(ek))) {
1376 >                                oldVal = ev;
1377 >                                if (!onlyIfAbsent)
1378 >                                    e.val = v;
1379 >                                break;
1380 >                            }
1381 >                            Node<V> last = e;
1382 >                            if ((e = e.next) == null) {
1383 >                                last.next = new Node<V>(h, k, v, null);
1384 >                                if (len >= TREE_THRESHOLD)
1385 >                                    replaceWithTreeBin(tab, i, k);
1386 >                                break;
1387 >                            }
1388 >                        }
1389 >                    }
1390 >                }
1391 >                if (len != 0) {
1392 >                    if (oldVal != null)
1393 >                        return oldVal;
1394 >                    break;
1395 >                }
1396 >            }
1397 >        }
1398 >        addCount(1L, len);
1399 >        return null;
1400 >    }
1401 >
1402 >    /** Implementation for computeIfAbsent */
1403 >    @SuppressWarnings("unchecked") private final V internalComputeIfAbsent
1404 >        (K k, Fun<? super K, ? extends V> mf) {
1405 >        if (k == null || mf == null)
1406 >            throw new NullPointerException();
1407          int h = spread(k.hashCode());
1408          V val = null;
1409 <        boolean added = false;
1410 <        boolean validated = false;
1411 <        Node[] tab = table;
498 <        do {
499 <            Node e; int i;
1409 >        int len = 0;
1410 >        for (Node<V>[] tab = table;;) {
1411 >            Node<V> f; int i; Object fk;
1412              if (tab == null)
1413 <                tab = grow(0);
1414 <            else if ((e = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1415 <                Node node = new Node(h, k, null, null);
1413 >                tab = initTable();
1414 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1415 >                Node<V> node = new Node<V>(h, k, null, null);
1416                  synchronized (node) {
1417                      if (casTabAt(tab, i, null, node)) {
1418 <                        validated = true;
1418 >                        len = 1;
1419                          try {
1420 <                            val = f.map(k);
509 <                            if (val != null) {
1420 >                            if ((val = mf.apply(k)) != null)
1421                                  node.val = val;
511                                added = true;
512                            }
1422                          } finally {
1423 <                            if (!added)
1423 >                            if (val == null)
1424                                  setTabAt(tab, i, null);
1425                          }
1426                      }
1427                  }
1428 +                if (len != 0)
1429 +                    break;
1430              }
1431 <            else if (e.hash < 0)
1432 <                tab = (Node[])e.key;
1433 <            else if (Thread.holdsLock(e))
1434 <                throw new IllegalStateException("Recursive map computation");
1435 <            else {
1436 <                boolean checkSize = false;
1437 <                synchronized (e) {
1438 <                    Node first = e;
1439 <                    for (;;) {
1440 <                        Object ek, ev;
1441 <                        if ((ev = e.val) == null)
1442 <                            break;
1443 <                        if (e.hash == h && (ek = e.key) != null &&
1444 <                            (k == ek || k.equals(ek))) {
1445 <                            if (tabAt(tab, i) == first) {
535 <                                validated = true;
536 <                                if (replace && (ev = f.map(k)) != null)
537 <                                    e.val = ev;
538 <                                val = (V)ev;
1431 >            else if (f.hash < 0) {
1432 >                if ((fk = f.key) instanceof TreeBin) {
1433 >                    TreeBin<V> t = (TreeBin<V>)fk;
1434 >                    boolean added = false;
1435 >                    t.acquire(0);
1436 >                    try {
1437 >                        if (tabAt(tab, i) == f) {
1438 >                            len = 1;
1439 >                            TreeNode<V> p = t.getTreeNode(h, k, t.root);
1440 >                            if (p != null)
1441 >                                val = p.val;
1442 >                            else if ((val = mf.apply(k)) != null) {
1443 >                                added = true;
1444 >                                len = 2;
1445 >                                t.putTreeNode(h, k, val);
1446                              }
540                            break;
1447                          }
1448 <                        Node last = e;
1449 <                        if ((e = e.next) == null) {
1450 <                            if (tabAt(tab, i) == first) {
1451 <                                validated = true;
1452 <                                if ((val = f.map(k)) != null) {
1453 <                                    last.next = new Node(h, k, val, null);
1448 >                    } finally {
1449 >                        t.release(0);
1450 >                    }
1451 >                    if (len != 0) {
1452 >                        if (!added)
1453 >                            return val;
1454 >                        break;
1455 >                    }
1456 >                }
1457 >                else
1458 >                    tab = (Node<V>[])fk;
1459 >            }
1460 >            else {
1461 >                for (Node<V> e = f; e != null; e = e.next) { // prescan
1462 >                    Object ek; V ev;
1463 >                    if (e.hash == h && (ev = e.val) != null &&
1464 >                        ((ek = e.key) == k || k.equals(ek)))
1465 >                        return ev;
1466 >                }
1467 >                boolean added = false;
1468 >                synchronized (f) {
1469 >                    if (tabAt(tab, i) == f) {
1470 >                        len = 1;
1471 >                        for (Node<V> e = f;; ++len) {
1472 >                            Object ek; V ev;
1473 >                            if (e.hash == h &&
1474 >                                (ev = e.val) != null &&
1475 >                                ((ek = e.key) == k || k.equals(ek))) {
1476 >                                val = ev;
1477 >                                break;
1478 >                            }
1479 >                            Node<V> last = e;
1480 >                            if ((e = e.next) == null) {
1481 >                                if ((val = mf.apply(k)) != null) {
1482                                      added = true;
1483 <                                    if (last != first || tab.length <= 64)
1484 <                                        checkSize = true;
1483 >                                    last.next = new Node<V>(h, k, val, null);
1484 >                                    if (len >= TREE_THRESHOLD)
1485 >                                        replaceWithTreeBin(tab, i, k);
1486                                  }
1487 +                                break;
1488                              }
553                            break;
1489                          }
1490                      }
1491                  }
1492 <                if (checkSize && tab.length < MAXIMUM_CAPACITY &&
1493 <                    resizing == 0 && counter.sum() >= threshold)
1494 <                    grow(0);
1495 <            }
1496 <        } while (!validated);
1497 <        if (added)
1498 <            counter.increment();
1492 >                if (len != 0) {
1493 >                    if (!added)
1494 >                        return val;
1495 >                    break;
1496 >                }
1497 >            }
1498 >        }
1499 >        if (val != null)
1500 >            addCount(1L, len);
1501          return val;
1502      }
1503  
1504 <    /*
1505 <     * Reclassifies nodes in each bin to new table.  Because we are
1506 <     * using power-of-two expansion, the elements from each bin must
1507 <     * either stay at same index, or move with a power of two
1508 <     * offset. We eliminate unnecessary node creation by catching
1509 <     * cases where old nodes can be reused because their next fields
1510 <     * won't change.  Statistically, at the default threshold, only
1511 <     * about one-sixth of them need cloning when a table doubles. The
1512 <     * nodes they replace will be garbage collectable as soon as they
1513 <     * are no longer referenced by any reader thread that may be in
1514 <     * the midst of concurrently traversing table.
1515 <     *
1516 <     * Transfers are done from the bottom up to preserve iterator
1517 <     * traversability. On each step, the old bin is locked,
1518 <     * moved/copied, and then replaced with a forwarding node.
1519 <     */
1520 <    private static final void transfer(Node[] tab, Node[] nextTab) {
1521 <        int n = tab.length;
1522 <        int mask = nextTab.length - 1;
1523 <        Node fwd = new Node(MOVED, nextTab, null, null);
1524 <        for (int i = n - 1; i >= 0; --i) {
1525 <            for (Node e;;) {
1526 <                if ((e = tabAt(tab, i)) == null) {
1527 <                    if (casTabAt(tab, i, e, fwd))
1528 <                        break;
592 <                }
593 <                else {
594 <                    boolean validated = false;
595 <                    synchronized (e) {
596 <                        int idx = e.hash & mask;
597 <                        Node lastRun = e;
598 <                        for (Node p = e.next; p != null; p = p.next) {
599 <                            int j = p.hash & mask;
600 <                            if (j != idx) {
601 <                                idx = j;
602 <                                lastRun = p;
1504 >    /** Implementation for compute */
1505 >    @SuppressWarnings("unchecked") private final V internalCompute
1506 >        (K k, boolean onlyIfPresent,
1507 >         BiFun<? super K, ? super V, ? extends V> mf) {
1508 >        if (k == null || mf == null)
1509 >            throw new NullPointerException();
1510 >        int h = spread(k.hashCode());
1511 >        V val = null;
1512 >        int delta = 0;
1513 >        int len = 0;
1514 >        for (Node<V>[] tab = table;;) {
1515 >            Node<V> f; int i, fh; Object fk;
1516 >            if (tab == null)
1517 >                tab = initTable();
1518 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1519 >                if (onlyIfPresent)
1520 >                    break;
1521 >                Node<V> node = new Node<V>(h, k, null, null);
1522 >                synchronized (node) {
1523 >                    if (casTabAt(tab, i, null, node)) {
1524 >                        try {
1525 >                            len = 1;
1526 >                            if ((val = mf.apply(k, null)) != null) {
1527 >                                node.val = val;
1528 >                                delta = 1;
1529                              }
1530 +                        } finally {
1531 +                            if (delta == 0)
1532 +                                setTabAt(tab, i, null);
1533                          }
1534 <                        if (tabAt(tab, i) == e) {
1535 <                            validated = true;
1536 <                            relaxedSetTabAt(nextTab, idx, lastRun);
1537 <                            for (Node p = e; p != lastRun; p = p.next) {
1538 <                                int h = p.hash;
1539 <                                int j = h & mask;
1540 <                                Node r = relaxedTabAt(nextTab, j);
1541 <                                relaxedSetTabAt(nextTab, j,
1542 <                                                new Node(h, p.key, p.val, r));
1534 >                    }
1535 >                }
1536 >                if (len != 0)
1537 >                    break;
1538 >            }
1539 >            else if ((fh = f.hash) < 0) {
1540 >                if ((fk = f.key) instanceof TreeBin) {
1541 >                    TreeBin<V> t = (TreeBin<V>)fk;
1542 >                    t.acquire(0);
1543 >                    try {
1544 >                        if (tabAt(tab, i) == f) {
1545 >                            len = 1;
1546 >                            TreeNode<V> p = t.getTreeNode(h, k, t.root);
1547 >                            if (p == null && onlyIfPresent)
1548 >                                break;
1549 >                            V pv = (p == null) ? null : p.val;
1550 >                            if ((val = mf.apply(k, pv)) != null) {
1551 >                                if (p != null)
1552 >                                    p.val = val;
1553 >                                else {
1554 >                                    len = 2;
1555 >                                    delta = 1;
1556 >                                    t.putTreeNode(h, k, val);
1557 >                                }
1558 >                            }
1559 >                            else if (p != null) {
1560 >                                delta = -1;
1561 >                                t.deleteTreeNode(p);
1562                              }
615                            setTabAt(tab, i, fwd);
1563                          }
1564 +                    } finally {
1565 +                        t.release(0);
1566                      }
1567 <                    if (validated)
1567 >                    if (len != 0)
1568                          break;
1569                  }
1570 +                else
1571 +                    tab = (Node<V>[])fk;
1572 +            }
1573 +            else {
1574 +                synchronized (f) {
1575 +                    if (tabAt(tab, i) == f) {
1576 +                        len = 1;
1577 +                        for (Node<V> e = f, pred = null;; ++len) {
1578 +                            Object ek; V ev;
1579 +                            if (e.hash == h &&
1580 +                                (ev = e.val) != null &&
1581 +                                ((ek = e.key) == k || k.equals(ek))) {
1582 +                                val = mf.apply(k, ev);
1583 +                                if (val != null)
1584 +                                    e.val = val;
1585 +                                else {
1586 +                                    delta = -1;
1587 +                                    Node<V> en = e.next;
1588 +                                    if (pred != null)
1589 +                                        pred.next = en;
1590 +                                    else
1591 +                                        setTabAt(tab, i, en);
1592 +                                }
1593 +                                break;
1594 +                            }
1595 +                            pred = e;
1596 +                            if ((e = e.next) == null) {
1597 +                                if (!onlyIfPresent &&
1598 +                                    (val = mf.apply(k, null)) != null) {
1599 +                                    pred.next = new Node<V>(h, k, val, null);
1600 +                                    delta = 1;
1601 +                                    if (len >= TREE_THRESHOLD)
1602 +                                        replaceWithTreeBin(tab, i, k);
1603 +                                }
1604 +                                break;
1605 +                            }
1606 +                        }
1607 +                    }
1608 +                }
1609 +                if (len != 0)
1610 +                    break;
1611              }
1612          }
1613 +        if (delta != 0)
1614 +            addCount((long)delta, len);
1615 +        return val;
1616      }
1617  
1618 <    /**
1619 <     * If not already resizing, initializes or creates next table and
1620 <     * transfers bins. Rechecks occupancy after a transfer to see if
1621 <     * another resize is already needed because resizings are lagging
1622 <     * additions.
1623 <     *
1624 <     * @param sizeHint overridden capacity target (nonzero only from putAll)
1625 <     * @return current table
1626 <     */
1627 <    private final Node[] grow(int sizeHint) {
1628 <        if (resizing == 0 &&
1629 <            UNSAFE.compareAndSwapInt(this, resizingOffset, 0, 1)) {
1630 <            try {
1631 <                for (;;) {
1632 <                    int cap, n;
1633 <                    Node[] tab = table;
1634 <                    if (tab == null) {
1635 <                        int c = initCap;
1636 <                        if (c < sizeHint)
1637 <                            c = sizeHint;
1638 <                        if (c == DEFAULT_CAPACITY)
1639 <                            cap = c;
1640 <                        else if (c >= MAXIMUM_CAPACITY)
1641 <                            cap = MAXIMUM_CAPACITY;
1642 <                        else {
1643 <                            cap = MINIMUM_CAPACITY;
1644 <                            while (cap < c)
1645 <                                cap <<= 1;
1618 >    /** Implementation for merge */
1619 >    @SuppressWarnings("unchecked") private final V internalMerge
1620 >        (K k, V v, BiFun<? super V, ? super V, ? extends V> mf) {
1621 >        if (k == null || v == null || mf == null)
1622 >            throw new NullPointerException();
1623 >        int h = spread(k.hashCode());
1624 >        V val = null;
1625 >        int delta = 0;
1626 >        int len = 0;
1627 >        for (Node<V>[] tab = table;;) {
1628 >            int i; Node<V> f; Object fk; V fv;
1629 >            if (tab == null)
1630 >                tab = initTable();
1631 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1632 >                if (casTabAt(tab, i, null, new Node<V>(h, k, v, null))) {
1633 >                    delta = 1;
1634 >                    val = v;
1635 >                    break;
1636 >                }
1637 >            }
1638 >            else if (f.hash < 0) {
1639 >                if ((fk = f.key) instanceof TreeBin) {
1640 >                    TreeBin<V> t = (TreeBin<V>)fk;
1641 >                    t.acquire(0);
1642 >                    try {
1643 >                        if (tabAt(tab, i) == f) {
1644 >                            len = 1;
1645 >                            TreeNode<V> p = t.getTreeNode(h, k, t.root);
1646 >                            val = (p == null) ? v : mf.apply(p.val, v);
1647 >                            if (val != null) {
1648 >                                if (p != null)
1649 >                                    p.val = val;
1650 >                                else {
1651 >                                    len = 2;
1652 >                                    delta = 1;
1653 >                                    t.putTreeNode(h, k, val);
1654 >                                }
1655 >                            }
1656 >                            else if (p != null) {
1657 >                                delta = -1;
1658 >                                t.deleteTreeNode(p);
1659 >                            }
1660                          }
1661 +                    } finally {
1662 +                        t.release(0);
1663                      }
1664 <                    else if ((n = tab.length) < MAXIMUM_CAPACITY &&
656 <                             (sizeHint <= 0 || n < sizeHint))
657 <                        cap = n << 1;
658 <                    else
659 <                        break;
660 <                    threshold = (int)(cap * loadFactor) - THRESHOLD_OFFSET;
661 <                    Node[] nextTab = new Node[cap];
662 <                    if (tab != null)
663 <                        transfer(tab, nextTab);
664 <                    table = nextTab;
665 <                    if (tab == null || cap >= MAXIMUM_CAPACITY ||
666 <                        (sizeHint > 0 && cap >= sizeHint) ||
667 <                        counter.sum() < threshold)
1664 >                    if (len != 0)
1665                          break;
1666                  }
1667 <            } finally {
1668 <                resizing = 0;
1667 >                else
1668 >                    tab = (Node<V>[])fk;
1669 >            }
1670 >            else {
1671 >                synchronized (f) {
1672 >                    if (tabAt(tab, i) == f) {
1673 >                        len = 1;
1674 >                        for (Node<V> e = f, pred = null;; ++len) {
1675 >                            Object ek; V ev;
1676 >                            if (e.hash == h &&
1677 >                                (ev = e.val) != null &&
1678 >                                ((ek = e.key) == k || k.equals(ek))) {
1679 >                                val = mf.apply(ev, v);
1680 >                                if (val != null)
1681 >                                    e.val = val;
1682 >                                else {
1683 >                                    delta = -1;
1684 >                                    Node<V> en = e.next;
1685 >                                    if (pred != null)
1686 >                                        pred.next = en;
1687 >                                    else
1688 >                                        setTabAt(tab, i, en);
1689 >                                }
1690 >                                break;
1691 >                            }
1692 >                            pred = e;
1693 >                            if ((e = e.next) == null) {
1694 >                                val = v;
1695 >                                pred.next = new Node<V>(h, k, val, null);
1696 >                                delta = 1;
1697 >                                if (len >= TREE_THRESHOLD)
1698 >                                    replaceWithTreeBin(tab, i, k);
1699 >                                break;
1700 >                            }
1701 >                        }
1702 >                    }
1703 >                }
1704 >                if (len != 0)
1705 >                    break;
1706              }
1707          }
1708 <        else if (table == null)
1709 <            Thread.yield(); // lost initialization race; just spin
1710 <        return table;
1708 >        if (delta != 0)
1709 >            addCount((long)delta, len);
1710 >        return val;
1711      }
1712  
1713 <    /**
1714 <     * Implementation for putAll and constructor with Map
1715 <     * argument. Tries to first override initial capacity or grow
1716 <     * based on map size to pre-allocate table space.
1717 <     */
1718 <    private final void internalPutAll(Map<? extends K, ? extends V> m) {
1719 <        int s = m.size();
1720 <        grow((s >= (MAXIMUM_CAPACITY >>> 1)) ? s : s + (s >>> 1));
1721 <        for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
1722 <            Object k = e.getKey();
1723 <            Object v = e.getValue();
1724 <            if (k == null || v == null)
1725 <                throw new NullPointerException();
1726 <            internalPut(k, v, true);
1713 >    /** Implementation for putAll */
1714 >    @SuppressWarnings("unchecked") private final void internalPutAll
1715 >        (Map<? extends K, ? extends V> m) {
1716 >        tryPresize(m.size());
1717 >        long delta = 0L;     // number of uncommitted additions
1718 >        boolean npe = false; // to throw exception on exit for nulls
1719 >        try {                // to clean up counts on other exceptions
1720 >            for (Map.Entry<?, ? extends V> entry : m.entrySet()) {
1721 >                Object k; V v;
1722 >                if (entry == null || (k = entry.getKey()) == null ||
1723 >                    (v = entry.getValue()) == null) {
1724 >                    npe = true;
1725 >                    break;
1726 >                }
1727 >                int h = spread(k.hashCode());
1728 >                for (Node<V>[] tab = table;;) {
1729 >                    int i; Node<V> f; int fh; Object fk;
1730 >                    if (tab == null)
1731 >                        tab = initTable();
1732 >                    else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
1733 >                        if (casTabAt(tab, i, null, new Node<V>(h, k, v, null))) {
1734 >                            ++delta;
1735 >                            break;
1736 >                        }
1737 >                    }
1738 >                    else if ((fh = f.hash) < 0) {
1739 >                        if ((fk = f.key) instanceof TreeBin) {
1740 >                            TreeBin<V> t = (TreeBin<V>)fk;
1741 >                            boolean validated = false;
1742 >                            t.acquire(0);
1743 >                            try {
1744 >                                if (tabAt(tab, i) == f) {
1745 >                                    validated = true;
1746 >                                    TreeNode<V> p = t.getTreeNode(h, k, t.root);
1747 >                                    if (p != null)
1748 >                                        p.val = v;
1749 >                                    else {
1750 >                                        t.putTreeNode(h, k, v);
1751 >                                        ++delta;
1752 >                                    }
1753 >                                }
1754 >                            } finally {
1755 >                                t.release(0);
1756 >                            }
1757 >                            if (validated)
1758 >                                break;
1759 >                        }
1760 >                        else
1761 >                            tab = (Node<V>[])fk;
1762 >                    }
1763 >                    else {
1764 >                        int len = 0;
1765 >                        synchronized (f) {
1766 >                            if (tabAt(tab, i) == f) {
1767 >                                len = 1;
1768 >                                for (Node<V> e = f;; ++len) {
1769 >                                    Object ek; V ev;
1770 >                                    if (e.hash == h &&
1771 >                                        (ev = e.val) != null &&
1772 >                                        ((ek = e.key) == k || k.equals(ek))) {
1773 >                                        e.val = v;
1774 >                                        break;
1775 >                                    }
1776 >                                    Node<V> last = e;
1777 >                                    if ((e = e.next) == null) {
1778 >                                        ++delta;
1779 >                                        last.next = new Node<V>(h, k, v, null);
1780 >                                        if (len >= TREE_THRESHOLD)
1781 >                                            replaceWithTreeBin(tab, i, k);
1782 >                                        break;
1783 >                                    }
1784 >                                }
1785 >                            }
1786 >                        }
1787 >                        if (len != 0) {
1788 >                            if (len > 1) {
1789 >                                addCount(delta, len);
1790 >                                delta = 0L;
1791 >                            }
1792 >                            break;
1793 >                        }
1794 >                    }
1795 >                }
1796 >            }
1797 >        } finally {
1798 >            if (delta != 0L)
1799 >                addCount(delta, 2);
1800          }
1801 +        if (npe)
1802 +            throw new NullPointerException();
1803      }
1804  
1805      /**
1806 <     * Implementation for clear. Steps through each bin, removing all nodes.
1806 >     * Implementation for clear. Steps through each bin, removing all
1807 >     * nodes.
1808       */
1809 <    private final void internalClear() {
1810 <        long deletions = 0L;
1809 >    @SuppressWarnings("unchecked") private final void internalClear() {
1810 >        long delta = 0L; // negative number of deletions
1811          int i = 0;
1812 <        Node[] tab = table;
1812 >        Node<V>[] tab = table;
1813          while (tab != null && i < tab.length) {
1814 <            Node e = tabAt(tab, i);
1815 <            if (e == null)
1814 >            Node<V> f = tabAt(tab, i);
1815 >            if (f == null)
1816                  ++i;
1817 <            else if (e.hash < 0)
1818 <                tab = (Node[])e.key;
1817 >            else if (f.hash < 0) {
1818 >                Object fk;
1819 >                if ((fk = f.key) instanceof TreeBin) {
1820 >                    TreeBin<V> t = (TreeBin<V>)fk;
1821 >                    t.acquire(0);
1822 >                    try {
1823 >                        if (tabAt(tab, i) == f) {
1824 >                            for (Node<V> p = t.first; p != null; p = p.next) {
1825 >                                if (p.val != null) { // (currently always true)
1826 >                                    p.val = null;
1827 >                                    --delta;
1828 >                                }
1829 >                            }
1830 >                            t.first = null;
1831 >                            t.root = null;
1832 >                            ++i;
1833 >                        }
1834 >                    } finally {
1835 >                        t.release(0);
1836 >                    }
1837 >                }
1838 >                else
1839 >                    tab = (Node<V>[])fk;
1840 >            }
1841              else {
1842 <                boolean validated = false;
1843 <                synchronized (e) {
1844 <                    if (tabAt(tab, i) == e) {
1845 <                        validated = true;
714 <                        do {
715 <                            if (e.val != null) {
1842 >                synchronized (f) {
1843 >                    if (tabAt(tab, i) == f) {
1844 >                        for (Node<V> e = f; e != null; e = e.next) {
1845 >                            if (e.val != null) {  // (currently always true)
1846                                  e.val = null;
1847 <                                ++deletions;
1847 >                                --delta;
1848                              }
1849 <                        } while ((e = e.next) != null);
1849 >                        }
1850                          setTabAt(tab, i, null);
1851 +                        ++i;
1852                      }
1853                  }
1854 <                if (validated) {
1855 <                    ++i;
1856 <                    if (deletions > THRESHOLD_OFFSET) { // bound lag in counts
1857 <                        counter.add(-deletions);
1858 <                        deletions = 0L;
1854 >            }
1855 >        }
1856 >        if (delta != 0L)
1857 >            addCount(delta, -1);
1858 >    }
1859 >
1860 >    /* ---------------- Table Initialization and Resizing -------------- */
1861 >
1862 >    /**
1863 >     * Returns a power of two table size for the given desired capacity.
1864 >     * See Hackers Delight, sec 3.2
1865 >     */
1866 >    private static final int tableSizeFor(int c) {
1867 >        int n = c - 1;
1868 >        n |= n >>> 1;
1869 >        n |= n >>> 2;
1870 >        n |= n >>> 4;
1871 >        n |= n >>> 8;
1872 >        n |= n >>> 16;
1873 >        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
1874 >    }
1875 >
1876 >    /**
1877 >     * Initializes table, using the size recorded in sizeCtl.
1878 >     */
1879 >    @SuppressWarnings("unchecked") private final Node<V>[] initTable() {
1880 >        Node<V>[] tab; int sc;
1881 >        while ((tab = table) == null) {
1882 >            if ((sc = sizeCtl) < 0)
1883 >                Thread.yield(); // lost initialization race; just spin
1884 >            else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
1885 >                try {
1886 >                    if ((tab = table) == null) {
1887 >                        int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
1888 >                        @SuppressWarnings("rawtypes") Node[] tb = new Node[n];
1889 >                        table = tab = (Node<V>[])tb;
1890 >                        sc = n - (n >>> 2);
1891                      }
1892 +                } finally {
1893 +                    sizeCtl = sc;
1894 +                }
1895 +                break;
1896 +            }
1897 +        }
1898 +        return tab;
1899 +    }
1900 +
1901 +    /**
1902 +     * Adds to count, and if table is too small and not already
1903 +     * resizing, initiates transfer. If already resizing, helps
1904 +     * perform transfer if work is available.  Rechecks occupancy
1905 +     * after a transfer to see if another resize is already needed
1906 +     * because resizings are lagging additions.
1907 +     *
1908 +     * @param x the count to add
1909 +     * @param check if <0, don't check resize, if <= 1 only check if uncontended
1910 +     */
1911 +    private final void addCount(long x, int check) {
1912 +        CounterCell[] as; long b, s;
1913 +        if ((as = counterCells) != null ||
1914 +            !U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
1915 +            CounterHashCode hc; CounterCell a; long v; int m;
1916 +            boolean uncontended = true;
1917 +            if ((hc = threadCounterHashCode.get()) == null ||
1918 +                as == null || (m = as.length - 1) < 0 ||
1919 +                (a = as[m & hc.code]) == null ||
1920 +                !(uncontended =
1921 +                  U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
1922 +                fullAddCount(x, hc, uncontended);
1923 +                return;
1924 +            }
1925 +            if (check <= 1)
1926 +                return;
1927 +            s = sumCount();
1928 +        }
1929 +        if (check >= 0) {
1930 +            Node<V>[] tab, nt; int sc;
1931 +            while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
1932 +                   tab.length < MAXIMUM_CAPACITY) {
1933 +                if (sc < 0) {
1934 +                    if (sc == -1 || transferIndex <= transferOrigin ||
1935 +                        (nt = nextTable) == null)
1936 +                        break;
1937 +                    if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
1938 +                        transfer(tab, nt);
1939                  }
1940 +                else if (U.compareAndSwapInt(this, SIZECTL, sc, -2))
1941 +                    transfer(tab, null);
1942 +                s = sumCount();
1943              }
1944          }
732        if (deletions != 0L)
733            counter.add(-deletions);
1945      }
1946  
1947      /**
1948 <     * Base class for key, value, and entry iterators, plus internal
1949 <     * implementations of public traversal-based methods, to avoid
1950 <     * duplicating traversal code.
1948 >     * Tries to presize table to accommodate the given number of elements.
1949 >     *
1950 >     * @param size number of elements (doesn't need to be perfectly accurate)
1951       */
1952 <    class HashIterator {
1953 <        private Node next;          // the next entry to return
1954 <        private Node[] tab;         // current table; updated if resized
1955 <        private Node lastReturned;  // the last entry returned, for remove
1956 <        private Object nextVal;     // cached value of next
1957 <        private int index;          // index of bin to use next
1958 <        private int baseIndex;      // current index of initial table
1959 <        private final int baseSize; // initial table size
1952 >    @SuppressWarnings("unchecked") private final void tryPresize(int size) {
1953 >        int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1954 >            tableSizeFor(size + (size >>> 1) + 1);
1955 >        int sc;
1956 >        while ((sc = sizeCtl) >= 0) {
1957 >            Node<V>[] tab = table; int n;
1958 >            if (tab == null || (n = tab.length) == 0) {
1959 >                n = (sc > c) ? sc : c;
1960 >                if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
1961 >                    try {
1962 >                        if (table == tab) {
1963 >                            @SuppressWarnings("rawtypes") Node[] tb = new Node[n];
1964 >                            table = (Node<V>[])tb;
1965 >                            sc = n - (n >>> 2);
1966 >                        }
1967 >                    } finally {
1968 >                        sizeCtl = sc;
1969 >                    }
1970 >                }
1971 >            }
1972 >            else if (c <= sc || n >= MAXIMUM_CAPACITY)
1973 >                break;
1974 >            else if (tab == table &&
1975 >                     U.compareAndSwapInt(this, SIZECTL, sc, -2))
1976 >                transfer(tab, null);
1977 >        }
1978 >    }
1979  
1980 <        HashIterator() {
1981 <            Node[] t = tab = table;
1982 <            if (t == null)
1983 <                baseSize = 0;
1984 <            else {
1985 <                baseSize = t.length;
1986 <                advance(null);
1980 >    /**
1981 >     * Moves and/or copies the nodes in each bin to new table. See
1982 >     * above for explanation.
1983 >     */
1984 >    @SuppressWarnings("unchecked") private final void transfer
1985 >        (Node<V>[] tab, Node<V>[] nextTab) {
1986 >        int n = tab.length, stride;
1987 >        if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
1988 >            stride = MIN_TRANSFER_STRIDE; // subdivide range
1989 >        if (nextTab == null) {            // initiating
1990 >            try {
1991 >                @SuppressWarnings("rawtypes") Node[] tb = new Node[n << 1];
1992 >                nextTab = (Node<V>[])tb;
1993 >            } catch (Throwable ex) {      // try to cope with OOME
1994 >                sizeCtl = Integer.MAX_VALUE;
1995 >                return;
1996 >            }
1997 >            nextTable = nextTab;
1998 >            transferOrigin = n;
1999 >            transferIndex = n;
2000 >            Node<V> rev = new Node<V>(MOVED, tab, null, null);
2001 >            for (int k = n; k > 0;) {    // progressively reveal ready slots
2002 >                int nextk = (k > stride) ? k - stride : 0;
2003 >                for (int m = nextk; m < k; ++m)
2004 >                    nextTab[m] = rev;
2005 >                for (int m = n + nextk; m < n + k; ++m)
2006 >                    nextTab[m] = rev;
2007 >                U.putOrderedInt(this, TRANSFERORIGIN, k = nextk);
2008              }
2009          }
2010 +        int nextn = nextTab.length;
2011 +        Node<V> fwd = new Node<V>(MOVED, nextTab, null, null);
2012 +        boolean advance = true;
2013 +        for (int i = 0, bound = 0;;) {
2014 +            int nextIndex, nextBound; Node<V> f; Object fk;
2015 +            while (advance) {
2016 +                if (--i >= bound)
2017 +                    advance = false;
2018 +                else if ((nextIndex = transferIndex) <= transferOrigin) {
2019 +                    i = -1;
2020 +                    advance = false;
2021 +                }
2022 +                else if (U.compareAndSwapInt
2023 +                         (this, TRANSFERINDEX, nextIndex,
2024 +                          nextBound = (nextIndex > stride ?
2025 +                                       nextIndex - stride : 0))) {
2026 +                    bound = nextBound;
2027 +                    i = nextIndex - 1;
2028 +                    advance = false;
2029 +                }
2030 +            }
2031 +            if (i < 0 || i >= n || i + n >= nextn) {
2032 +                for (int sc;;) {
2033 +                    if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) {
2034 +                        if (sc == -1) {
2035 +                            nextTable = null;
2036 +                            table = nextTab;
2037 +                            sizeCtl = (n << 1) - (n >>> 1);
2038 +                        }
2039 +                        return;
2040 +                    }
2041 +                }
2042 +            }
2043 +            else if ((f = tabAt(tab, i)) == null) {
2044 +                if (casTabAt(tab, i, null, fwd)) {
2045 +                    setTabAt(nextTab, i, null);
2046 +                    setTabAt(nextTab, i + n, null);
2047 +                    advance = true;
2048 +                }
2049 +            }
2050 +            else if (f.hash >= 0) {
2051 +                synchronized (f) {
2052 +                    if (tabAt(tab, i) == f) {
2053 +                        int runBit = f.hash & n;
2054 +                        Node<V> lastRun = f, lo = null, hi = null;
2055 +                        for (Node<V> p = f.next; p != null; p = p.next) {
2056 +                            int b = p.hash & n;
2057 +                            if (b != runBit) {
2058 +                                runBit = b;
2059 +                                lastRun = p;
2060 +                            }
2061 +                        }
2062 +                        if (runBit == 0)
2063 +                            lo = lastRun;
2064 +                        else
2065 +                            hi = lastRun;
2066 +                        for (Node<V> p = f; p != lastRun; p = p.next) {
2067 +                            int ph = p.hash;
2068 +                            Object pk = p.key; V pv = p.val;
2069 +                            if ((ph & n) == 0)
2070 +                                lo = new Node<V>(ph, pk, pv, lo);
2071 +                            else
2072 +                                hi = new Node<V>(ph, pk, pv, hi);
2073 +                        }
2074 +                        setTabAt(nextTab, i, lo);
2075 +                        setTabAt(nextTab, i + n, hi);
2076 +                        setTabAt(tab, i, fwd);
2077 +                        advance = true;
2078 +                    }
2079 +                }
2080 +            }
2081 +            else if ((fk = f.key) instanceof TreeBin) {
2082 +                TreeBin<V> t = (TreeBin<V>)fk;
2083 +                t.acquire(0);
2084 +                try {
2085 +                    if (tabAt(tab, i) == f) {
2086 +                        TreeBin<V> lt = new TreeBin<V>();
2087 +                        TreeBin<V> ht = new TreeBin<V>();
2088 +                        int lc = 0, hc = 0;
2089 +                        for (Node<V> e = t.first; e != null; e = e.next) {
2090 +                            int h = e.hash;
2091 +                            Object k = e.key; V v = e.val;
2092 +                            if ((h & n) == 0) {
2093 +                                ++lc;
2094 +                                lt.putTreeNode(h, k, v);
2095 +                            }
2096 +                            else {
2097 +                                ++hc;
2098 +                                ht.putTreeNode(h, k, v);
2099 +                            }
2100 +                        }
2101 +                        Node<V> ln, hn; // throw away trees if too small
2102 +                        if (lc < TREE_THRESHOLD) {
2103 +                            ln = null;
2104 +                            for (Node<V> p = lt.first; p != null; p = p.next)
2105 +                                ln = new Node<V>(p.hash, p.key, p.val, ln);
2106 +                        }
2107 +                        else
2108 +                            ln = new Node<V>(MOVED, lt, null, null);
2109 +                        setTabAt(nextTab, i, ln);
2110 +                        if (hc < TREE_THRESHOLD) {
2111 +                            hn = null;
2112 +                            for (Node<V> p = ht.first; p != null; p = p.next)
2113 +                                hn = new Node<V>(p.hash, p.key, p.val, hn);
2114 +                        }
2115 +                        else
2116 +                            hn = new Node<V>(MOVED, ht, null, null);
2117 +                        setTabAt(nextTab, i + n, hn);
2118 +                        setTabAt(tab, i, fwd);
2119 +                        advance = true;
2120 +                    }
2121 +                } finally {
2122 +                    t.release(0);
2123 +                }
2124 +            }
2125 +            else
2126 +                advance = true; // already processed
2127 +        }
2128 +    }
2129  
2130 <        public final boolean hasNext()         { return next != null; }
761 <        public final boolean hasMoreElements() { return next != null; }
2130 >    /* ---------------- Counter support -------------- */
2131  
2132 <        /**
2133 <         * Advances next.  Normally, iteration proceeds bin-by-bin
2134 <         * traversing lists.  However, if the table has been resized,
2135 <         * then all future steps must traverse both the bin at the
2136 <         * current index as well as at (index + baseSize); and so on
2137 <         * for further resizings. To paranoically cope with potential
2138 <         * (improper) sharing of iterators across threads, table reads
2139 <         * are bounds-checked.
2140 <         */
2141 <        final void advance(Node e) {
2142 <            for (;;) {
2143 <                Node[] t; int i; // for bounds checks
2144 <                if (e != null) {
2145 <                    Object ek = e.key, ev = e.val;
2146 <                    if (ev != null && ek != null) {
2147 <                        nextVal = ev;
2148 <                        next = e;
2149 <                        break;
2132 >    final long sumCount() {
2133 >        CounterCell[] as = counterCells; CounterCell a;
2134 >        long sum = baseCount;
2135 >        if (as != null) {
2136 >            for (int i = 0; i < as.length; ++i) {
2137 >                if ((a = as[i]) != null)
2138 >                    sum += a.value;
2139 >            }
2140 >        }
2141 >        return sum;
2142 >    }
2143 >
2144 >    // See LongAdder version for explanation
2145 >    private final void fullAddCount(long x, CounterHashCode hc,
2146 >                                    boolean wasUncontended) {
2147 >        int h;
2148 >        if (hc == null) {
2149 >            hc = new CounterHashCode();
2150 >            int s = counterHashCodeGenerator.addAndGet(SEED_INCREMENT);
2151 >            h = hc.code = (s == 0) ? 1 : s; // Avoid zero
2152 >            threadCounterHashCode.set(hc);
2153 >        }
2154 >        else
2155 >            h = hc.code;
2156 >        boolean collide = false;                // True if last slot nonempty
2157 >        for (;;) {
2158 >            CounterCell[] as; CounterCell a; int n; long v;
2159 >            if ((as = counterCells) != null && (n = as.length) > 0) {
2160 >                if ((a = as[(n - 1) & h]) == null) {
2161 >                    if (counterBusy == 0) {            // Try to attach new Cell
2162 >                        CounterCell r = new CounterCell(x); // Optimistic create
2163 >                        if (counterBusy == 0 &&
2164 >                            U.compareAndSwapInt(this, COUNTERBUSY, 0, 1)) {
2165 >                            boolean created = false;
2166 >                            try {               // Recheck under lock
2167 >                                CounterCell[] rs; int m, j;
2168 >                                if ((rs = counterCells) != null &&
2169 >                                    (m = rs.length) > 0 &&
2170 >                                    rs[j = (m - 1) & h] == null) {
2171 >                                    rs[j] = r;
2172 >                                    created = true;
2173 >                                }
2174 >                            } finally {
2175 >                                counterBusy = 0;
2176 >                            }
2177 >                            if (created)
2178 >                                break;
2179 >                            continue;           // Slot is now non-empty
2180 >                        }
2181                      }
2182 <                    e = e.next;
2182 >                    collide = false;
2183                  }
2184 <                else if (baseIndex < baseSize && (t = tab) != null &&
2185 <                         t.length > (i = index) && i >= 0) {
2186 <                    if ((e = tabAt(t, i)) != null && e.hash < 0) {
2187 <                        tab = (Node[])e.key;
2188 <                        e = null;
2184 >                else if (!wasUncontended)       // CAS already known to fail
2185 >                    wasUncontended = true;      // Continue after rehash
2186 >                else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
2187 >                    break;
2188 >                else if (counterCells != as || n >= NCPU)
2189 >                    collide = false;            // At max size or stale
2190 >                else if (!collide)
2191 >                    collide = true;
2192 >                else if (counterBusy == 0 &&
2193 >                         U.compareAndSwapInt(this, COUNTERBUSY, 0, 1)) {
2194 >                    try {
2195 >                        if (counterCells == as) {// Expand table unless stale
2196 >                            CounterCell[] rs = new CounterCell[n << 1];
2197 >                            for (int i = 0; i < n; ++i)
2198 >                                rs[i] = as[i];
2199 >                            counterCells = rs;
2200 >                        }
2201 >                    } finally {
2202 >                        counterBusy = 0;
2203                      }
2204 <                    else if (i + baseSize < t.length)
2205 <                        index += baseSize;    // visit forwarded upper slots
792 <                    else
793 <                        index = ++baseIndex;
2204 >                    collide = false;
2205 >                    continue;                   // Retry with expanded table
2206                  }
2207 <                else {
2208 <                    next = null;
2209 <                    break;
2207 >                h ^= h << 13;                   // Rehash
2208 >                h ^= h >>> 17;
2209 >                h ^= h << 5;
2210 >            }
2211 >            else if (counterBusy == 0 && counterCells == as &&
2212 >                     U.compareAndSwapInt(this, COUNTERBUSY, 0, 1)) {
2213 >                boolean init = false;
2214 >                try {                           // Initialize table
2215 >                    if (counterCells == as) {
2216 >                        CounterCell[] rs = new CounterCell[2];
2217 >                        rs[h & 1] = new CounterCell(x);
2218 >                        counterCells = rs;
2219 >                        init = true;
2220 >                    }
2221 >                } finally {
2222 >                    counterBusy = 0;
2223                  }
2224 +                if (init)
2225 +                    break;
2226              }
2227 +            else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
2228 +                break;                          // Fall back on using base
2229          }
2230 +        hc.code = h;                            // Record index for next time
2231 +    }
2232  
2233 <        final Object nextKey() {
803 <            Node e = next;
804 <            if (e == null)
805 <                throw new NoSuchElementException();
806 <            Object k = e.key;
807 <            advance((lastReturned = e).next);
808 <            return k;
809 <        }
2233 >    /* ----------------Table Traversal -------------- */
2234  
2235 <        final Object nextValue() {
2236 <            Node e = next;
2237 <            if (e == null)
2238 <                throw new NoSuchElementException();
2239 <            Object v = nextVal;
2240 <            advance((lastReturned = e).next);
2241 <            return v;
2235 >    /**
2236 >     * Encapsulates traversal for methods such as containsValue; also
2237 >     * serves as a base class for other iterators and bulk tasks.
2238 >     *
2239 >     * At each step, the iterator snapshots the key ("nextKey") and
2240 >     * value ("nextVal") of a valid node (i.e., one that, at point of
2241 >     * snapshot, has a non-null user value). Because val fields can
2242 >     * change (including to null, indicating deletion), field nextVal
2243 >     * might not be accurate at point of use, but still maintains the
2244 >     * weak consistency property of holding a value that was once
2245 >     * valid. To support iterator.remove, the nextKey field is not
2246 >     * updated (nulled out) when the iterator cannot advance.
2247 >     *
2248 >     * Internal traversals directly access these fields, as in:
2249 >     * {@code while (it.advance() != null) { process(it.nextKey); }}
2250 >     *
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
2267 >     * must traverse both the bin at the current index as well as at
2268 >     * (index + baseSize); and so on for further resizings. To
2269 >     * paranoically cope with potential sharing by users of iterators
2270 >     * across threads, iteration terminates if a bounds checks fails
2271 >     * for a table read.
2272 >     *
2273 >     * This class extends CountedCompleter to streamline parallel
2274 >     * iteration in bulk operations. This adds only a few fields of
2275 >     * space overhead, which is small enough in cases where it is not
2276 >     * needed to not worry about it.  Because CountedCompleter is
2277 >     * Serializable, but iterators need not be, we need to add warning
2278 >     * suppressions.
2279 >     */
2280 >    @SuppressWarnings("serial") static class Traverser<K,V,R>
2281 >        extends CountedCompleter<R> {
2282 >        final ConcurrentHashMapV8<K,V> map;
2283 >        Node<V> next;        // the next entry to use
2284 >        Object nextKey;      // cached key field of next
2285 >        V nextVal;           // cached val field of next
2286 >        Node<V>[] tab;       // current table; updated if resized
2287 >        int index;           // index of bin to use next
2288 >        int baseIndex;       // current index of initial table
2289 >        int baseLimit;       // index bound for initial table
2290 >        int baseSize;        // initial table size
2291 >        int batch;           // split control
2292 >
2293 >        /** Creates iterator for all entries in the table. */
2294 >        Traverser(ConcurrentHashMapV8<K,V> map) {
2295 >            this.map = map;
2296 >        }
2297 >
2298 >        /** Creates iterator for split() methods and task constructors */
2299 >        Traverser(ConcurrentHashMapV8<K,V> map, Traverser<K,V,?> it, int batch) {
2300 >            super(it);
2301 >            this.batch = batch;
2302 >            if ((this.map = map) != null && it != null) { // split parent
2303 >                Node<V>[] t;
2304 >                if ((t = it.tab) == null &&
2305 >                    (t = it.tab = map.table) != null)
2306 >                    it.baseLimit = it.baseSize = t.length;
2307 >                this.tab = t;
2308 >                this.baseSize = it.baseSize;
2309 >                int hi = this.baseLimit = it.baseLimit;
2310 >                it.baseLimit = this.index = this.baseIndex =
2311 >                    (hi + it.baseIndex + 1) >>> 1;
2312 >            }
2313          }
2314  
2315 <        final WriteThroughEntry nextEntry() {
2316 <            Node e = next;
2317 <            if (e == null)
2318 <                throw new NoSuchElementException();
2319 <            WriteThroughEntry entry =
2320 <                new WriteThroughEntry(e.key, nextVal);
2321 <            advance((lastReturned = e).next);
2322 <            return entry;
2315 >        /**
2316 >         * Advances next; returns nextVal or null if terminated.
2317 >         * See above for explanation.
2318 >         */
2319 >        @SuppressWarnings("unchecked") final V advance() {
2320 >            Node<V> e = next;
2321 >            V ev = null;
2322 >            outer: do {
2323 >                if (e != null)                  // advance past used/skipped node
2324 >                    e = e.next;
2325 >                while (e == null) {             // get to next non-null bin
2326 >                    ConcurrentHashMapV8<K,V> m;
2327 >                    Node<V>[] t; int b, i, n; Object ek; //  must use locals
2328 >                    if ((t = tab) != null)
2329 >                        n = t.length;
2330 >                    else if ((m = map) != null && (t = tab = m.table) != null)
2331 >                        n = baseLimit = baseSize = t.length;
2332 >                    else
2333 >                        break outer;
2334 >                    if ((b = baseIndex) >= baseLimit ||
2335 >                        (i = index) < 0 || i >= n)
2336 >                        break outer;
2337 >                    if ((e = tabAt(t, i)) != null && e.hash < 0) {
2338 >                        if ((ek = e.key) instanceof TreeBin)
2339 >                            e = ((TreeBin<V>)ek).first;
2340 >                        else {
2341 >                            tab = (Node<V>[])ek;
2342 >                            continue;           // restarts due to null val
2343 >                        }
2344 >                    }                           // visit upper slots if present
2345 >                    index = (i += baseSize) < n ? i : (baseIndex = b + 1);
2346 >                }
2347 >                nextKey = e.key;
2348 >            } while ((ev = e.val) == null);    // skip deleted or special nodes
2349 >            next = e;
2350 >            return nextVal = ev;
2351          }
2352  
2353          public final void remove() {
2354 <            if (lastReturned == null)
2354 >            Object k = nextKey;
2355 >            if (k == null && (advance() == null || (k = nextKey) == null))
2356                  throw new IllegalStateException();
2357 <            ConcurrentHashMapV8.this.remove(lastReturned.key);
834 <            lastReturned = null;
2357 >            map.internalReplace(k, null, null);
2358          }
2359  
2360 <        /** Helper for serialization */
2361 <        final void writeEntries(java.io.ObjectOutputStream s)
839 <            throws java.io.IOException {
840 <            Node e;
841 <            while ((e = next) != null) {
842 <                s.writeObject(e.key);
843 <                s.writeObject(nextVal);
844 <                advance(e.next);
845 <            }
2360 >        public final boolean hasNext() {
2361 >            return nextVal != null || advance() != null;
2362          }
2363  
2364 <        /** Helper for containsValue */
849 <        final boolean containsVal(Object value) {
850 <            if (value != null) {
851 <                Node e;
852 <                while ((e = next) != null) {
853 <                    Object v = nextVal;
854 <                    if (value == v || value.equals(v))
855 <                        return true;
856 <                    advance(e.next);
857 <                }
858 <            }
859 <            return false;
860 <        }
2364 >        public final boolean hasMoreElements() { return hasNext(); }
2365  
2366 <        /** Helper for Map.hashCode */
863 <        final int mapHashCode() {
864 <            int h = 0;
865 <            Node e;
866 <            while ((e = next) != null) {
867 <                h += e.key.hashCode() ^ nextVal.hashCode();
868 <                advance(e.next);
869 <            }
870 <            return h;
871 <        }
2366 >        public void compute() { } // default no-op CountedCompleter body
2367  
2368 <        /** Helper for Map.toString */
2369 <        final String mapToString() {
2370 <            Node e = next;
2371 <            if (e == null)
2372 <                return "{}";
2373 <            StringBuilder sb = new StringBuilder();
2374 <            sb.append('{');
2375 <            for (;;) {
2376 <                sb.append(e.key   == this ? "(this Map)" : e.key);
2377 <                sb.append('=');
2378 <                sb.append(nextVal == this ? "(this Map)" : nextVal);
2379 <                advance(e.next);
2380 <                if ((e = next) != null)
2381 <                    sb.append(',').append(' ');
2382 <                else
2383 <                    return sb.append('}').toString();
2368 >        /**
2369 >         * Returns a batch value > 0 if this task should (and must) be
2370 >         * split, if so, adding to pending count, and in any case
2371 >         * updating batch value. The initial batch value is approx
2372 >         * exp2 of the number of times (minus one) to split task by
2373 >         * two before executing leaf action. This value is faster to
2374 >         * compute and more convenient to use as a guide to splitting
2375 >         * than is the depth, since it is used while dividing by two
2376 >         * anyway.
2377 >         */
2378 >        final int preSplit() {
2379 >            ConcurrentHashMapV8<K,V> m; int b; Node<V>[] t;  ForkJoinPool pool;
2380 >            if ((b = batch) < 0 && (m = map) != null) { // force initialization
2381 >                if ((t = tab) == null && (t = tab = m.table) != null)
2382 >                    baseLimit = baseSize = t.length;
2383 >                if (t != null) {
2384 >                    long n = m.sumCount();
2385 >                    int par = ((pool = getPool()) == null) ?
2386 >                        ForkJoinPool.getCommonPoolParallelism() :
2387 >                        pool.getParallelism();
2388 >                    int sp = par << 3; // slack of 8
2389 >                    b = (n <= 0L) ? 0 : (n < (long)sp) ? (int)n : sp;
2390 >                }
2391              }
2392 +            b = (b <= 1 || baseIndex == baseLimit) ? 0 : (b >>> 1);
2393 +            if ((batch = b) > 0)
2394 +                addToPendingCount(1);
2395 +            return b;
2396          }
2397 +
2398      }
2399  
2400      /* ---------------- Public operations -------------- */
2401  
2402      /**
2403 <     * Creates a new, empty map with the specified initial
897 <     * capacity, load factor and concurrency level.
898 <     *
899 <     * @param initialCapacity the initial capacity. The implementation
900 <     * performs internal sizing to accommodate this many elements.
901 <     * @param loadFactor  the load factor threshold, used to control resizing.
902 <     * Resizing may be performed when the average number of elements per
903 <     * bin exceeds this threshold.
904 <     * @param concurrencyLevel the estimated number of concurrently
905 <     * updating threads. The implementation may use this value as
906 <     * a sizing hint.
907 <     * @throws IllegalArgumentException if the initial capacity is
908 <     * negative or the load factor or concurrencyLevel are
909 <     * nonpositive.
2403 >     * Creates a new, empty map with the default initial table size (16).
2404       */
2405 <    public ConcurrentHashMapV8(int initialCapacity,
912 <                             float loadFactor, int concurrencyLevel) {
913 <        if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
914 <            throw new IllegalArgumentException();
915 <        this.initCap = initialCapacity;
916 <        this.loadFactor = loadFactor;
917 <        this.counter = new LongAdder();
2405 >    public ConcurrentHashMapV8() {
2406      }
2407  
2408      /**
2409 <     * Creates a new, empty map with the specified initial capacity
2410 <     * and load factor and with the default concurrencyLevel (16).
2409 >     * Creates a new, empty map with an initial table size
2410 >     * accommodating the specified number of elements without the need
2411 >     * to dynamically resize.
2412       *
2413       * @param initialCapacity The implementation performs internal
2414       * sizing to accommodate this many elements.
2415 <     * @param loadFactor  the load factor threshold, used to control resizing.
2416 <     * Resizing may be performed when the average number of elements per
2417 <     * bin exceeds this threshold.
2415 >     * @throws IllegalArgumentException if the initial capacity of
2416 >     * elements is negative
2417 >     */
2418 >    public ConcurrentHashMapV8(int initialCapacity) {
2419 >        if (initialCapacity < 0)
2420 >            throw new IllegalArgumentException();
2421 >        int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
2422 >                   MAXIMUM_CAPACITY :
2423 >                   tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
2424 >        this.sizeCtl = cap;
2425 >    }
2426 >
2427 >    /**
2428 >     * Creates a new map with the same mappings as the given map.
2429 >     *
2430 >     * @param m the map
2431 >     */
2432 >    public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) {
2433 >        this.sizeCtl = DEFAULT_CAPACITY;
2434 >        internalPutAll(m);
2435 >    }
2436 >
2437 >    /**
2438 >     * Creates a new, empty map with an initial table size based on
2439 >     * the given number of elements ({@code initialCapacity}) and
2440 >     * initial table density ({@code loadFactor}).
2441 >     *
2442 >     * @param initialCapacity the initial capacity. The implementation
2443 >     * performs internal sizing to accommodate this many elements,
2444 >     * given the specified load factor.
2445 >     * @param loadFactor the load factor (table density) for
2446 >     * establishing the initial table size
2447       * @throws IllegalArgumentException if the initial capacity of
2448       * elements is negative or the load factor is nonpositive
2449       *
2450       * @since 1.6
2451       */
2452      public ConcurrentHashMapV8(int initialCapacity, float loadFactor) {
2453 <        this(initialCapacity, loadFactor, DEFAULT_CONCURRENCY_LEVEL);
2453 >        this(initialCapacity, loadFactor, 1);
2454      }
2455  
2456      /**
2457 <     * Creates a new, empty map with the specified initial capacity,
2458 <     * and with default load factor (0.75) and concurrencyLevel (16).
2457 >     * Creates a new, empty map with an initial table size based on
2458 >     * the given number of elements ({@code initialCapacity}), table
2459 >     * density ({@code loadFactor}), and number of concurrently
2460 >     * updating threads ({@code concurrencyLevel}).
2461       *
2462       * @param initialCapacity the initial capacity. The implementation
2463 <     * performs internal sizing to accommodate this many elements.
2464 <     * @throws IllegalArgumentException if the initial capacity of
2465 <     * elements is negative.
2463 >     * performs internal sizing to accommodate this many elements,
2464 >     * given the specified load factor.
2465 >     * @param loadFactor the load factor (table density) for
2466 >     * establishing the initial table size
2467 >     * @param concurrencyLevel the estimated number of concurrently
2468 >     * updating threads. The implementation may use this value as
2469 >     * a sizing hint.
2470 >     * @throws IllegalArgumentException if the initial capacity is
2471 >     * negative or the load factor or concurrencyLevel are
2472 >     * nonpositive
2473       */
2474 <    public ConcurrentHashMapV8(int initialCapacity) {
2475 <        this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
2474 >    public ConcurrentHashMapV8(int initialCapacity,
2475 >                               float loadFactor, int concurrencyLevel) {
2476 >        if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
2477 >            throw new IllegalArgumentException();
2478 >        if (initialCapacity < concurrencyLevel)   // Use at least as many bins
2479 >            initialCapacity = concurrencyLevel;   // as estimated threads
2480 >        long size = (long)(1.0 + (long)initialCapacity / loadFactor);
2481 >        int cap = (size >= (long)MAXIMUM_CAPACITY) ?
2482 >            MAXIMUM_CAPACITY : tableSizeFor((int)size);
2483 >        this.sizeCtl = cap;
2484      }
2485  
2486      /**
2487 <     * Creates a new, empty map with a default initial capacity (16),
2488 <     * load factor (0.75) and concurrencyLevel (16).
2487 >     * Creates a new {@link Set} backed by a ConcurrentHashMapV8
2488 >     * from the given type to {@code Boolean.TRUE}.
2489 >     *
2490 >     * @return the new set
2491       */
2492 <    public ConcurrentHashMapV8() {
2493 <        this(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
2492 >    public static <K> KeySetView<K,Boolean> newKeySet() {
2493 >        return new KeySetView<K,Boolean>(new ConcurrentHashMapV8<K,Boolean>(),
2494 >                                      Boolean.TRUE);
2495      }
2496  
2497      /**
2498 <     * Creates a new map with the same mappings as the given map.
2499 <     * The map is created with a capacity of 1.5 times the number
962 <     * of mappings in the given map or 16 (whichever is greater),
963 <     * and a default load factor (0.75) and concurrencyLevel (16).
2498 >     * Creates a new {@link Set} backed by a ConcurrentHashMapV8
2499 >     * from the given type to {@code Boolean.TRUE}.
2500       *
2501 <     * @param m the map
2501 >     * @param initialCapacity The implementation performs internal
2502 >     * sizing to accommodate this many elements.
2503 >     * @throws IllegalArgumentException if the initial capacity of
2504 >     * elements is negative
2505 >     * @return the new set
2506       */
2507 <    public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) {
2508 <        this(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
2509 <        if (m == null)
970 <            throw new NullPointerException();
971 <        internalPutAll(m);
2507 >    public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
2508 >        return new KeySetView<K,Boolean>
2509 >            (new ConcurrentHashMapV8<K,Boolean>(initialCapacity), Boolean.TRUE);
2510      }
2511  
2512      /**
2513 <     * Returns {@code true} if this map contains no key-value mappings.
976 <     *
977 <     * @return {@code true} if this map contains no key-value mappings
2513 >     * {@inheritDoc}
2514       */
2515      public boolean isEmpty() {
2516 <        return counter.sum() <= 0L; // ignore transient negative values
2516 >        return sumCount() <= 0L; // ignore transient negative values
2517      }
2518  
2519      /**
2520 <     * Returns the number of key-value mappings in this map.  If the
985 <     * map contains more than {@code Integer.MAX_VALUE} elements, returns
986 <     * {@code Integer.MAX_VALUE}.
987 <     *
988 <     * @return the number of key-value mappings in this map
2520 >     * {@inheritDoc}
2521       */
2522      public int size() {
2523 <        long n = counter.sum();
2524 <        return (n <= 0L) ? 0 :
2525 <            (n >= Integer.MAX_VALUE) ? Integer.MAX_VALUE :
2526 <            (int)n;
2523 >        long n = sumCount();
2524 >        return ((n < 0L) ? 0 :
2525 >                (n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
2526 >                (int)n);
2527 >    }
2528 >
2529 >    /**
2530 >     * Returns the number of mappings. This method should be used
2531 >     * instead of {@link #size} because a ConcurrentHashMapV8 may
2532 >     * contain more mappings than can be represented as an int. The
2533 >     * value returned is an estimate; the actual count may differ if
2534 >     * there are concurrent insertions or removals.
2535 >     *
2536 >     * @return the number of mappings
2537 >     */
2538 >    public long mappingCount() {
2539 >        long n = sumCount();
2540 >        return (n < 0L) ? 0L : n; // ignore transient negative values
2541      }
2542  
2543      /**
# Line 1005 | Line 2551 | public class ConcurrentHashMapV8<K, V>
2551       *
2552       * @throws NullPointerException if the specified key is null
2553       */
1008    @SuppressWarnings("unchecked")
2554      public V get(Object key) {
2555 <        if (key == null)
2556 <            throw new NullPointerException();
2557 <        return (V)internalGet(key);
2555 >        return internalGet(key);
2556 >    }
2557 >
2558 >    /**
2559 >     * Returns the value to which the specified key is mapped,
2560 >     * or the given defaultValue if this map contains no mapping for the key.
2561 >     *
2562 >     * @param key the key
2563 >     * @param defaultValue the value to return if this map contains
2564 >     * no mapping for the given key
2565 >     * @return the mapping for the key, if present; else the defaultValue
2566 >     * @throws NullPointerException if the specified key is null
2567 >     */
2568 >    public V getValueOrDefault(Object key, V defaultValue) {
2569 >        V v;
2570 >        return (v = internalGet(key)) == null ? defaultValue : v;
2571      }
2572  
2573      /**
2574       * Tests if the specified object is a key in this table.
2575       *
2576 <     * @param  key   possible key
2576 >     * @param  key possible key
2577       * @return {@code true} if and only if the specified object
2578       *         is a key in this table, as determined by the
2579 <     *         {@code equals} method; {@code false} otherwise.
2579 >     *         {@code equals} method; {@code false} otherwise
2580       * @throws NullPointerException if the specified key is null
2581       */
2582      public boolean containsKey(Object key) {
1025        if (key == null)
1026            throw new NullPointerException();
2583          return internalGet(key) != null;
2584      }
2585  
2586      /**
2587       * Returns {@code true} if this map maps one or more keys to the
2588 <     * specified value. Note: This method requires a full internal
2589 <     * traversal of the hash table, and so is much slower than
1034 <     * method {@code containsKey}.
2588 >     * specified value. Note: This method may require a full traversal
2589 >     * of the map, and is much slower than method {@code containsKey}.
2590       *
2591       * @param value value whose presence in this map is to be tested
2592       * @return {@code true} if this map maps one or more keys to the
# Line 1041 | Line 2596 | public class ConcurrentHashMapV8<K, V>
2596      public boolean containsValue(Object value) {
2597          if (value == null)
2598              throw new NullPointerException();
2599 <        return new HashIterator().containsVal(value);
2599 >        V v;
2600 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
2601 >        while ((v = it.advance()) != null) {
2602 >            if (v == value || value.equals(v))
2603 >                return true;
2604 >        }
2605 >        return false;
2606      }
2607  
2608      /**
# Line 1059 | Line 2620 | public class ConcurrentHashMapV8<K, V>
2620       *         {@code false} otherwise
2621       * @throws NullPointerException if the specified value is null
2622       */
2623 <    public boolean contains(Object value) {
2623 >    @Deprecated public boolean contains(Object value) {
2624          return containsValue(value);
2625      }
2626  
# Line 1067 | Line 2628 | public class ConcurrentHashMapV8<K, V>
2628       * Maps the specified key to the specified value in this table.
2629       * Neither the key nor the value can be null.
2630       *
2631 <     * <p> The value can be retrieved by calling the {@code get} method
2631 >     * <p>The value can be retrieved by calling the {@code get} method
2632       * with a key that is equal to the original key.
2633       *
2634       * @param key key with which the specified value is to be associated
# Line 1076 | Line 2637 | public class ConcurrentHashMapV8<K, V>
2637       *         {@code null} if there was no mapping for {@code key}
2638       * @throws NullPointerException if the specified key or value is null
2639       */
1079    @SuppressWarnings("unchecked")
2640      public V put(K key, V value) {
2641 <        if (key == null || value == null)
1082 <            throw new NullPointerException();
1083 <        return (V)internalPut(key, value, true);
2641 >        return internalPut(key, value, false);
2642      }
2643  
2644      /**
# Line 1090 | Line 2648 | public class ConcurrentHashMapV8<K, V>
2648       *         or {@code null} if there was no mapping for the key
2649       * @throws NullPointerException if the specified key or value is null
2650       */
1093    @SuppressWarnings("unchecked")
2651      public V putIfAbsent(K key, V value) {
2652 <        if (key == null || value == null)
1096 <            throw new NullPointerException();
1097 <        return (V)internalPut(key, value, false);
2652 >        return internalPut(key, value, true);
2653      }
2654  
2655      /**
# Line 1105 | Line 2660 | public class ConcurrentHashMapV8<K, V>
2660       * @param m mappings to be stored in this map
2661       */
2662      public void putAll(Map<? extends K, ? extends V> m) {
1108        if (m == null)
1109            throw new NullPointerException();
2663          internalPutAll(m);
2664      }
2665  
2666      /**
2667       * If the specified key is not already associated with a value,
2668 <     * computes its value using the given mappingFunction, and if
2669 <     * non-null, enters it into the map.  This is equivalent to
2670 <     *
2671 <     * <pre>
2672 <     *   if (map.containsKey(key))
2673 <     *       return map.get(key);
2674 <     *   value = mappingFunction.map(key);
2675 <     *   if (value != null)
2676 <     *      map.put(key, value);
2677 <     *   return value;
2678 <     * </pre>
2679 <     *
2680 <     * except that the action is performed atomically.  Some attempted
2681 <     * update operations on this map by other threads may be blocked
2682 <     * while computation is in progress, so the computation should be
2683 <     * short and simple, and must not attempt to update any other
2684 <     * mappings of this Map. The most appropriate usage is to
2668 >     * computes its value using the given mappingFunction and enters
2669 >     * it into the map unless null.  This is equivalent to
2670 >     * <pre> {@code
2671 >     * if (map.containsKey(key))
2672 >     *   return map.get(key);
2673 >     * value = mappingFunction.apply(key);
2674 >     * if (value != null)
2675 >     *   map.put(key, value);
2676 >     * return value;}</pre>
2677 >     *
2678 >     * except that the action is performed atomically.  If the
2679 >     * function returns {@code null} no mapping is recorded. If the
2680 >     * function itself throws an (unchecked) exception, the exception
2681 >     * is rethrown to its caller, and no mapping is recorded.  Some
2682 >     * attempted update operations on this map by other threads may be
2683 >     * blocked while computation is in progress, so the computation
2684 >     * should be short and simple, and must not attempt to update any
2685 >     * other mappings of this Map. The most appropriate usage is to
2686       * construct a new object serving as an initial mapped value, or
2687       * memoized result, as in:
2688 <     * <pre>{@code
2689 <     * map.computeIfAbsent(key, new MappingFunction<K, V>() {
2690 <     *   public V map(K k) { return new Value(f(k)); }};
2691 <     * }</pre>
2688 >     *
2689 >     *  <pre> {@code
2690 >     * map.computeIfAbsent(key, new Fun<K,V>() {
2691 >     *   public V map(K k) { return new Value(f(k)); }});}</pre>
2692       *
2693       * @param key key with which the specified value is to be associated
2694       * @param mappingFunction the function to compute a value
2695       * @return the current (existing or computed) value associated with
2696 <     *         the specified key, or {@code null} if the computation
1143 <     *         returned {@code null}.
2696 >     *         the specified key, or null if the computed value is null
2697       * @throws NullPointerException if the specified key or mappingFunction
2698 <     *         is null,
2698 >     *         is null
2699       * @throws IllegalStateException if the computation detectably
2700       *         attempts a recursive update to this map that would
2701 <     *         otherwise never complete.
2701 >     *         otherwise never complete
2702       * @throws RuntimeException or Error if the mappingFunction does so,
2703 <     *         in which case the mapping is left unestablished.
2703 >     *         in which case the mapping is left unestablished
2704       */
2705 <    public V computeIfAbsent(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2706 <        if (key == null || mappingFunction == null)
2707 <            throw new NullPointerException();
1155 <        return internalCompute(key, mappingFunction, false);
2705 >    public V computeIfAbsent
2706 >        (K key, Fun<? super K, ? extends V> mappingFunction) {
2707 >        return internalComputeIfAbsent(key, mappingFunction);
2708      }
2709  
2710      /**
2711 <     * Computes the value associated with the given key using the given
2712 <     * mappingFunction, and if non-null, enters it into the map.  This
2713 <     * is equivalent to
2711 >     * If the given key is present, computes a new mapping value given a key and
2712 >     * its current mapped value. This is equivalent to
2713 >     *  <pre> {@code
2714 >     *   if (map.containsKey(key)) {
2715 >     *     value = remappingFunction.apply(key, map.get(key));
2716 >     *     if (value != null)
2717 >     *       map.put(key, value);
2718 >     *     else
2719 >     *       map.remove(key);
2720 >     *   }
2721 >     * }</pre>
2722       *
2723 <     * <pre>
2724 <     *   value = mappingFunction.map(key);
2723 >     * except that the action is performed atomically.  If the
2724 >     * function returns {@code null}, the mapping is removed.  If the
2725 >     * function itself throws an (unchecked) exception, the exception
2726 >     * is rethrown to its caller, and the current mapping is left
2727 >     * unchanged.  Some attempted update operations on this map by
2728 >     * other threads may be blocked while computation is in progress,
2729 >     * so the computation should be short and simple, and must not
2730 >     * attempt to update any other mappings of this Map. For example,
2731 >     * to either create or append new messages to a value mapping:
2732 >     *
2733 >     * @param key key with which the specified value is to be associated
2734 >     * @param remappingFunction the function to compute a value
2735 >     * @return the new value associated with the specified key, or null if none
2736 >     * @throws NullPointerException if the specified key or remappingFunction
2737 >     *         is null
2738 >     * @throws IllegalStateException if the computation detectably
2739 >     *         attempts a recursive update to this map that would
2740 >     *         otherwise never complete
2741 >     * @throws RuntimeException or Error if the remappingFunction does so,
2742 >     *         in which case the mapping is unchanged
2743 >     */
2744 >    public V computeIfPresent
2745 >        (K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) {
2746 >        return internalCompute(key, true, remappingFunction);
2747 >    }
2748 >
2749 >    /**
2750 >     * Computes a new mapping value given a key and
2751 >     * its current mapped value (or {@code null} if there is no current
2752 >     * mapping). This is equivalent to
2753 >     *  <pre> {@code
2754 >     *   value = remappingFunction.apply(key, map.get(key));
2755       *   if (value != null)
2756 <     *      map.put(key, value);
2756 >     *     map.put(key, value);
2757       *   else
2758 <     *      value = map.get(key);
2759 <     *   return value;
2760 <     * </pre>
2761 <     *
2762 <     * except that the action is performed atomically.  Some attempted
2763 <     * update operations on this map by other threads may be blocked
2764 <     * while computation is in progress, so the computation should be
2765 <     * short and simple, and must not attempt to update any other
2766 <     * mappings of this Map.
2758 >     *     map.remove(key);
2759 >     * }</pre>
2760 >     *
2761 >     * except that the action is performed atomically.  If the
2762 >     * function returns {@code null}, the mapping is removed.  If the
2763 >     * function itself throws an (unchecked) exception, the exception
2764 >     * is rethrown to its caller, and the current mapping is left
2765 >     * unchanged.  Some attempted update operations on this map by
2766 >     * other threads may be blocked while computation is in progress,
2767 >     * so the computation should be short and simple, and must not
2768 >     * attempt to update any other mappings of this Map. For example,
2769 >     * to either create or append new messages to a value mapping:
2770 >     *
2771 >     * <pre> {@code
2772 >     * Map<Key, String> map = ...;
2773 >     * final String msg = ...;
2774 >     * map.compute(key, new BiFun<Key, String, String>() {
2775 >     *   public String apply(Key k, String v) {
2776 >     *    return (v == null) ? msg : v + msg;});}}</pre>
2777       *
2778       * @param key key with which the specified value is to be associated
2779 <     * @param mappingFunction the function to compute a value
2780 <     * @return the current value associated with
2781 <     *         the specified key, or {@code null} if the computation
2782 <     *         returned {@code null} and the value was not otherwise present.
1183 <     * @throws NullPointerException if the specified key or mappingFunction
1184 <     *         is null,
2779 >     * @param remappingFunction the function to compute a value
2780 >     * @return the new value associated with the specified key, or null if none
2781 >     * @throws NullPointerException if the specified key or remappingFunction
2782 >     *         is null
2783       * @throws IllegalStateException if the computation detectably
2784       *         attempts a recursive update to this map that would
2785 <     *         otherwise never complete.
2786 <     * @throws RuntimeException or Error if the mappingFunction does so,
2787 <     *         in which case the mapping is unchanged.
2788 <     */
2789 <    public V compute(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2790 <        if (key == null || mappingFunction == null)
2791 <            throw new NullPointerException();
2792 <        return internalCompute(key, mappingFunction, true);
2785 >     *         otherwise never complete
2786 >     * @throws RuntimeException or Error if the remappingFunction does so,
2787 >     *         in which case the mapping is unchanged
2788 >     */
2789 >    public V compute
2790 >        (K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) {
2791 >        return internalCompute(key, false, remappingFunction);
2792 >    }
2793 >
2794 >    /**
2795 >     * If the specified key is not already associated
2796 >     * with a value, associate it with the given value.
2797 >     * Otherwise, replace the value with the results of
2798 >     * the given remapping function. This is equivalent to:
2799 >     *  <pre> {@code
2800 >     *   if (!map.containsKey(key))
2801 >     *     map.put(value);
2802 >     *   else {
2803 >     *     newValue = remappingFunction.apply(map.get(key), value);
2804 >     *     if (value != null)
2805 >     *       map.put(key, value);
2806 >     *     else
2807 >     *       map.remove(key);
2808 >     *   }
2809 >     * }</pre>
2810 >     * except that the action is performed atomically.  If the
2811 >     * function returns {@code null}, the mapping is removed.  If the
2812 >     * function itself throws an (unchecked) exception, the exception
2813 >     * is rethrown to its caller, and the current mapping is left
2814 >     * unchanged.  Some attempted update operations on this map by
2815 >     * other threads may be blocked while computation is in progress,
2816 >     * so the computation should be short and simple, and must not
2817 >     * attempt to update any other mappings of this Map.
2818 >     */
2819 >    public V merge
2820 >        (K key, V value,
2821 >         BiFun<? super V, ? super V, ? extends V> remappingFunction) {
2822 >        return internalMerge(key, value, remappingFunction);
2823      }
2824  
2825      /**
# Line 1203 | Line 2831 | public class ConcurrentHashMapV8<K, V>
2831       *         {@code null} if there was no mapping for {@code key}
2832       * @throws NullPointerException if the specified key is null
2833       */
1206    @SuppressWarnings("unchecked")
2834      public V remove(Object key) {
2835 <        if (key == null)
1209 <            throw new NullPointerException();
1210 <        return (V)internalReplace(key, null, null);
2835 >        return internalReplace(key, null, null);
2836      }
2837  
2838      /**
# Line 1216 | Line 2841 | public class ConcurrentHashMapV8<K, V>
2841       * @throws NullPointerException if the specified key is null
2842       */
2843      public boolean remove(Object key, Object value) {
2844 <        if (key == null)
1220 <            throw new NullPointerException();
1221 <        if (value == null)
1222 <            return false;
1223 <        return internalReplace(key, null, value) != null;
2844 >        return value != null && internalReplace(key, null, value) != null;
2845      }
2846  
2847      /**
# Line 1241 | Line 2862 | public class ConcurrentHashMapV8<K, V>
2862       *         or {@code null} if there was no mapping for the key
2863       * @throws NullPointerException if the specified key or value is null
2864       */
1244    @SuppressWarnings("unchecked")
2865      public V replace(K key, V value) {
2866          if (key == null || value == null)
2867              throw new NullPointerException();
2868 <        return (V)internalReplace(key, value, null);
2868 >        return internalReplace(key, value, null);
2869      }
2870  
2871      /**
# Line 1258 | Line 2878 | public class ConcurrentHashMapV8<K, V>
2878      /**
2879       * Returns a {@link Set} view of the keys contained in this map.
2880       * The set is backed by the map, so changes to the map are
2881 <     * reflected in the set, and vice-versa.  The set supports element
1262 <     * removal, which removes the corresponding mapping from this map,
1263 <     * via the {@code Iterator.remove}, {@code Set.remove},
1264 <     * {@code removeAll}, {@code retainAll}, and {@code clear}
1265 <     * operations.  It does not support the {@code add} or
1266 <     * {@code addAll} operations.
2881 >     * reflected in the set, and vice-versa.
2882       *
2883 <     * <p>The view's {@code iterator} is a "weakly consistent" iterator
2884 <     * that will never throw {@link ConcurrentModificationException},
2885 <     * and guarantees to traverse elements as they existed upon
2886 <     * construction of the iterator, and may (but is not guaranteed to)
2887 <     * reflect any modifications subsequent to construction.
2883 >     * @return the set view
2884 >     */
2885 >    public KeySetView<K,V> keySet() {
2886 >        KeySetView<K,V> ks = keySet;
2887 >        return (ks != null) ? ks : (keySet = new KeySetView<K,V>(this, null));
2888 >    }
2889 >
2890 >    /**
2891 >     * Returns a {@link Set} view of the keys in this map, using the
2892 >     * given common mapped value for any additions (i.e., {@link
2893 >     * Collection#add} and {@link Collection#addAll}). This is of
2894 >     * course only appropriate if it is acceptable to use the same
2895 >     * value for all additions from this view.
2896 >     *
2897 >     * @param mappedValue the mapped value to use for any additions
2898 >     * @return the set view
2899 >     * @throws NullPointerException if the mappedValue is null
2900       */
2901 <    public Set<K> keySet() {
2902 <        Set<K> ks = keySet;
2903 <        return (ks != null) ? ks : (keySet = new KeySet());
2901 >    public KeySetView<K,V> keySet(V mappedValue) {
2902 >        if (mappedValue == null)
2903 >            throw new NullPointerException();
2904 >        return new KeySetView<K,V>(this, mappedValue);
2905      }
2906  
2907      /**
2908       * Returns a {@link Collection} view of the values contained in this map.
2909       * The collection is backed by the map, so changes to the map are
2910 <     * reflected in the collection, and vice-versa.  The collection
1283 <     * supports element removal, which removes the corresponding
1284 <     * mapping from this map, via the {@code Iterator.remove},
1285 <     * {@code Collection.remove}, {@code removeAll},
1286 <     * {@code retainAll}, and {@code clear} operations.  It does not
1287 <     * support the {@code add} or {@code addAll} operations.
1288 <     *
1289 <     * <p>The view's {@code iterator} is a "weakly consistent" iterator
1290 <     * that will never throw {@link ConcurrentModificationException},
1291 <     * and guarantees to traverse elements as they existed upon
1292 <     * construction of the iterator, and may (but is not guaranteed to)
1293 <     * reflect any modifications subsequent to construction.
2910 >     * reflected in the collection, and vice-versa.
2911       */
2912 <    public Collection<V> values() {
2913 <        Collection<V> vs = values;
2914 <        return (vs != null) ? vs : (values = new Values());
2912 >    public ValuesView<K,V> values() {
2913 >        ValuesView<K,V> vs = values;
2914 >        return (vs != null) ? vs : (values = new ValuesView<K,V>(this));
2915      }
2916  
2917      /**
# Line 1314 | Line 2931 | public class ConcurrentHashMapV8<K, V>
2931       * reflect any modifications subsequent to construction.
2932       */
2933      public Set<Map.Entry<K,V>> entrySet() {
2934 <        Set<Map.Entry<K,V>> es = entrySet;
2935 <        return (es != null) ? es : (entrySet = new EntrySet());
2934 >        EntrySetView<K,V> es = entrySet;
2935 >        return (es != null) ? es : (entrySet = new EntrySetView<K,V>(this));
2936      }
2937  
2938      /**
# Line 1325 | Line 2942 | public class ConcurrentHashMapV8<K, V>
2942       * @see #keySet()
2943       */
2944      public Enumeration<K> keys() {
2945 <        return new KeyIterator();
2945 >        return new KeyIterator<K,V>(this);
2946      }
2947  
2948      /**
# Line 1335 | Line 2952 | public class ConcurrentHashMapV8<K, V>
2952       * @see #values()
2953       */
2954      public Enumeration<V> elements() {
2955 <        return new ValueIterator();
2955 >        return new ValueIterator<K,V>(this);
2956 >    }
2957 >
2958 >    /**
2959 >     * Returns a partitionable iterator of the keys in this map.
2960 >     *
2961 >     * @return a partitionable iterator of the keys in this map
2962 >     */
2963 >    public Spliterator<K> keySpliterator() {
2964 >        return new KeyIterator<K,V>(this);
2965 >    }
2966 >
2967 >    /**
2968 >     * Returns a partitionable iterator of the values in this map.
2969 >     *
2970 >     * @return a partitionable iterator of the values in this map
2971 >     */
2972 >    public Spliterator<V> valueSpliterator() {
2973 >        return new ValueIterator<K,V>(this);
2974 >    }
2975 >
2976 >    /**
2977 >     * Returns a partitionable iterator of the entries in this map.
2978 >     *
2979 >     * @return a partitionable iterator of the entries in this map
2980 >     */
2981 >    public Spliterator<Map.Entry<K,V>> entrySpliterator() {
2982 >        return new EntryIterator<K,V>(this);
2983      }
2984  
2985      /**
# Line 1346 | Line 2990 | public class ConcurrentHashMapV8<K, V>
2990       * @return the hash code value for this map
2991       */
2992      public int hashCode() {
2993 <        return new HashIterator().mapHashCode();
2993 >        int h = 0;
2994 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
2995 >        V v;
2996 >        while ((v = it.advance()) != null) {
2997 >            h += it.nextKey.hashCode() ^ v.hashCode();
2998 >        }
2999 >        return h;
3000      }
3001  
3002      /**
# Line 1361 | Line 3011 | public class ConcurrentHashMapV8<K, V>
3011       * @return a string representation of this map
3012       */
3013      public String toString() {
3014 <        return new HashIterator().mapToString();
3014 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3015 >        StringBuilder sb = new StringBuilder();
3016 >        sb.append('{');
3017 >        V v;
3018 >        if ((v = it.advance()) != null) {
3019 >            for (;;) {
3020 >                Object k = it.nextKey;
3021 >                sb.append(k == this ? "(this Map)" : k);
3022 >                sb.append('=');
3023 >                sb.append(v == this ? "(this Map)" : v);
3024 >                if ((v = it.advance()) == null)
3025 >                    break;
3026 >                sb.append(',').append(' ');
3027 >            }
3028 >        }
3029 >        return sb.append('}').toString();
3030      }
3031  
3032      /**
# Line 1375 | Line 3040 | public class ConcurrentHashMapV8<K, V>
3040       * @return {@code true} if the specified object is equal to this map
3041       */
3042      public boolean equals(Object o) {
3043 <        if (o == this)
3044 <            return true;
3045 <        if (!(o instanceof Map))
3046 <            return false;
3047 <        Map<?,?> m = (Map<?,?>) o;
3048 <        try {
3049 <            for (Map.Entry<K,V> e : this.entrySet())
3050 <                if (! e.getValue().equals(m.get(e.getKey())))
3043 >        if (o != this) {
3044 >            if (!(o instanceof Map))
3045 >                return false;
3046 >            Map<?,?> m = (Map<?,?>) o;
3047 >            Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3048 >            V val;
3049 >            while ((val = it.advance()) != null) {
3050 >                Object v = m.get(it.nextKey);
3051 >                if (v == null || (v != val && !v.equals(val)))
3052                      return false;
3053 +            }
3054              for (Map.Entry<?,?> e : m.entrySet()) {
3055 <                Object k = e.getKey();
3056 <                Object v = e.getValue();
3057 <                if (k == null || v == null || !v.equals(get(k)))
3055 >                Object mk, mv, v;
3056 >                if ((mk = e.getKey()) == null ||
3057 >                    (mv = e.getValue()) == null ||
3058 >                    (v = internalGet(mk)) == null ||
3059 >                    (mv != v && !mv.equals(v)))
3060                      return false;
3061              }
1393            return true;
1394        } catch (ClassCastException unused) {
1395            return false;
1396        } catch (NullPointerException unused) {
1397            return false;
3062          }
3063 +        return true;
3064      }
3065  
3066 <    /**
1402 <     * Custom Entry class used by EntryIterator.next(), that relays
1403 <     * setValue changes to the underlying map.
1404 <     */
1405 <    final class WriteThroughEntry extends AbstractMap.SimpleEntry<K,V> {
1406 <        @SuppressWarnings("unchecked")
1407 <        WriteThroughEntry(Object k, Object v) {
1408 <            super((K)k, (V)v);
1409 <        }
3066 >    /* ----------------Iterators -------------- */
3067  
3068 <        /**
3069 <         * Sets our entry's value and writes through to the map. The
3070 <         * value to return is somewhat arbitrary here. Since a
3071 <         * WriteThroughEntry does not necessarily track asynchronous
3072 <         * changes, the most recent "previous" value could be
3073 <         * different from what we return (or could even have been
3074 <         * removed in which case the put will re-establish). We do not
3075 <         * and cannot guarantee more.
3076 <         */
3077 <        public V setValue(V value) {
3078 <            if (value == null) throw new NullPointerException();
3079 <            V v = super.setValue(value);
3080 <            ConcurrentHashMapV8.this.put(getKey(), value);
3081 <            return v;
3068 >    @SuppressWarnings("serial") static final class KeyIterator<K,V>
3069 >        extends Traverser<K,V,Object>
3070 >        implements Spliterator<K>, Enumeration<K> {
3071 >        KeyIterator(ConcurrentHashMapV8<K,V> map) { super(map); }
3072 >        KeyIterator(ConcurrentHashMapV8<K,V> map, Traverser<K,V,Object> it) {
3073 >            super(map, it, -1);
3074 >        }
3075 >        public KeyIterator<K,V> split() {
3076 >            if (nextKey != null)
3077 >                throw new IllegalStateException();
3078 >            return new KeyIterator<K,V>(map, this);
3079 >        }
3080 >        @SuppressWarnings("unchecked") public final K next() {
3081 >            if (nextVal == null && advance() == null)
3082 >                throw new NoSuchElementException();
3083 >            Object k = nextKey;
3084 >            nextVal = null;
3085 >            return (K) k;
3086          }
1426    }
1427
1428    final class KeyIterator extends HashIterator
1429        implements Iterator<K>, Enumeration<K> {
1430        @SuppressWarnings("unchecked")
1431        public final K next()        { return (K)super.nextKey(); }
1432        @SuppressWarnings("unchecked")
1433        public final K nextElement() { return (K)super.nextKey(); }
1434    }
1435
1436    final class ValueIterator extends HashIterator
1437        implements Iterator<V>, Enumeration<V> {
1438        @SuppressWarnings("unchecked")
1439        public final V next()        { return (V)super.nextValue(); }
1440        @SuppressWarnings("unchecked")
1441        public final V nextElement() { return (V)super.nextValue(); }
1442    }
3087  
3088 <    final class EntryIterator extends HashIterator
1445 <        implements Iterator<Entry<K,V>> {
1446 <        public final Map.Entry<K,V> next() { return super.nextEntry(); }
3088 >        public final K nextElement() { return next(); }
3089      }
3090  
3091 <    final class KeySet extends AbstractSet<K> {
3092 <        public int size() {
3093 <            return ConcurrentHashMapV8.this.size();
3094 <        }
3095 <        public boolean isEmpty() {
3096 <            return ConcurrentHashMapV8.this.isEmpty();
1455 <        }
1456 <        public void clear() {
1457 <            ConcurrentHashMapV8.this.clear();
3091 >    @SuppressWarnings("serial") static final class ValueIterator<K,V>
3092 >        extends Traverser<K,V,Object>
3093 >        implements Spliterator<V>, Enumeration<V> {
3094 >        ValueIterator(ConcurrentHashMapV8<K,V> map) { super(map); }
3095 >        ValueIterator(ConcurrentHashMapV8<K,V> map, Traverser<K,V,Object> it) {
3096 >            super(map, it, -1);
3097          }
3098 <        public Iterator<K> iterator() {
3099 <            return new KeyIterator();
3100 <        }
3101 <        public boolean contains(Object o) {
1463 <            return ConcurrentHashMapV8.this.containsKey(o);
3098 >        public ValueIterator<K,V> split() {
3099 >            if (nextKey != null)
3100 >                throw new IllegalStateException();
3101 >            return new ValueIterator<K,V>(map, this);
3102          }
3103 <        public boolean remove(Object o) {
3104 <            return ConcurrentHashMapV8.this.remove(o) != null;
3103 >
3104 >        public final V next() {
3105 >            V v;
3106 >            if ((v = nextVal) == null && (v = advance()) == null)
3107 >                throw new NoSuchElementException();
3108 >            nextVal = null;
3109 >            return v;
3110          }
3111 +
3112 +        public final V nextElement() { return next(); }
3113      }
3114  
3115 <    final class Values extends AbstractCollection<V> {
3116 <        public int size() {
3117 <            return ConcurrentHashMapV8.this.size();
3115 >    @SuppressWarnings("serial") static final class EntryIterator<K,V>
3116 >        extends Traverser<K,V,Object>
3117 >        implements Spliterator<Map.Entry<K,V>> {
3118 >        EntryIterator(ConcurrentHashMapV8<K,V> map) { super(map); }
3119 >        EntryIterator(ConcurrentHashMapV8<K,V> map, Traverser<K,V,Object> it) {
3120 >            super(map, it, -1);
3121          }
3122 <        public boolean isEmpty() {
3123 <            return ConcurrentHashMapV8.this.isEmpty();
3124 <        }
3125 <        public void clear() {
1478 <            ConcurrentHashMapV8.this.clear();
1479 <        }
1480 <        public Iterator<V> iterator() {
1481 <            return new ValueIterator();
3122 >        public EntryIterator<K,V> split() {
3123 >            if (nextKey != null)
3124 >                throw new IllegalStateException();
3125 >            return new EntryIterator<K,V>(map, this);
3126          }
3127 <        public boolean contains(Object o) {
3128 <            return ConcurrentHashMapV8.this.containsValue(o);
3127 >
3128 >        @SuppressWarnings("unchecked") public final Map.Entry<K,V> next() {
3129 >            V v;
3130 >            if ((v = nextVal) == null && (v = advance()) == null)
3131 >                throw new NoSuchElementException();
3132 >            Object k = nextKey;
3133 >            nextVal = null;
3134 >            return new MapEntry<K,V>((K)k, v, map);
3135          }
3136      }
3137  
3138 <    final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
3139 <        public int size() {
3140 <            return ConcurrentHashMapV8.this.size();
3141 <        }
3142 <        public boolean isEmpty() {
3143 <            return ConcurrentHashMapV8.this.isEmpty();
3144 <        }
3145 <        public void clear() {
3146 <            ConcurrentHashMapV8.this.clear();
3138 >    /**
3139 >     * Exported Entry for iterators
3140 >     */
3141 >    static final class MapEntry<K,V> implements Map.Entry<K,V> {
3142 >        final K key; // non-null
3143 >        V val;       // non-null
3144 >        final ConcurrentHashMapV8<K,V> map;
3145 >        MapEntry(K key, V val, ConcurrentHashMapV8<K,V> map) {
3146 >            this.key = key;
3147 >            this.val = val;
3148 >            this.map = map;
3149          }
3150 <        public Iterator<Map.Entry<K,V>> iterator() {
3151 <            return new EntryIterator();
3150 >        public final K getKey()       { return key; }
3151 >        public final V getValue()     { return val; }
3152 >        public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
3153 >        public final String toString(){ return key + "=" + val; }
3154 >
3155 >        public final boolean equals(Object o) {
3156 >            Object k, v; Map.Entry<?,?> e;
3157 >            return ((o instanceof Map.Entry) &&
3158 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
3159 >                    (v = e.getValue()) != null &&
3160 >                    (k == key || k.equals(key)) &&
3161 >                    (v == val || v.equals(val)));
3162          }
3163 <        public boolean contains(Object o) {
3164 <            if (!(o instanceof Map.Entry))
3165 <                return false;
3166 <            Map.Entry<?,?> e = (Map.Entry<?,?>)o;
3167 <            V v = ConcurrentHashMapV8.this.get(e.getKey());
3168 <            return v != null && v.equals(e.getValue());
3169 <        }
3170 <        public boolean remove(Object o) {
3171 <            if (!(o instanceof Map.Entry))
3172 <                return false;
3173 <            Map.Entry<?,?> e = (Map.Entry<?,?>)o;
3174 <            return ConcurrentHashMapV8.this.remove(e.getKey(), e.getValue());
3163 >
3164 >        /**
3165 >         * Sets our entry's value and writes through to the map. The
3166 >         * value to return is somewhat arbitrary here. Since we do not
3167 >         * necessarily track asynchronous changes, the most recent
3168 >         * "previous" value could be different from what we return (or
3169 >         * could even have been removed in which case the put will
3170 >         * re-establish). We do not and cannot guarantee more.
3171 >         */
3172 >        public final V setValue(V value) {
3173 >            if (value == null) throw new NullPointerException();
3174 >            V v = val;
3175 >            val = value;
3176 >            map.put(key, value);
3177 >            return v;
3178          }
3179      }
3180  
3181 +    /**
3182 +     * Returns exportable snapshot entry for the given key and value
3183 +     * when write-through can't or shouldn't be used.
3184 +     */
3185 +    static <K,V> AbstractMap.SimpleEntry<K,V> entryFor(K k, V v) {
3186 +        return new AbstractMap.SimpleEntry<K,V>(k, v);
3187 +    }
3188 +
3189      /* ---------------- Serialization Support -------------- */
3190  
3191      /**
3192 <     * Helper class used in previous version, declared for the sake of
3193 <     * serialization compatibility
3192 >     * Stripped-down version of helper class used in previous version,
3193 >     * declared for the sake of serialization compatibility
3194       */
3195 <    static class Segment<K,V> extends java.util.concurrent.locks.ReentrantLock
1523 <        implements Serializable {
3195 >    static class Segment<K,V> implements Serializable {
3196          private static final long serialVersionUID = 2249069246763182397L;
3197          final float loadFactor;
3198          Segment(float lf) { this.loadFactor = lf; }
# Line 1535 | Line 3207 | public class ConcurrentHashMapV8<K, V>
3207       * for each key-value mapping, followed by a null pair.
3208       * The key-value mappings are emitted in no particular order.
3209       */
3210 <    @SuppressWarnings("unchecked")
3211 <    private void writeObject(java.io.ObjectOutputStream s)
3212 <            throws java.io.IOException {
3210 >    @SuppressWarnings("unchecked") private void writeObject
3211 >        (java.io.ObjectOutputStream s)
3212 >        throws java.io.IOException {
3213          if (segments == null) { // for serialization compatibility
3214              segments = (Segment<K,V>[])
3215                  new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
3216              for (int i = 0; i < segments.length; ++i)
3217 <                segments[i] = new Segment<K,V>(loadFactor);
3217 >                segments[i] = new Segment<K,V>(LOAD_FACTOR);
3218          }
3219          s.defaultWriteObject();
3220 <        new HashIterator().writeEntries(s);
3220 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3221 >        V v;
3222 >        while ((v = it.advance()) != null) {
3223 >            s.writeObject(it.nextKey);
3224 >            s.writeObject(v);
3225 >        }
3226          s.writeObject(null);
3227          s.writeObject(null);
3228          segments = null; // throw away
3229      }
3230  
3231      /**
3232 <     * Reconstitutes the  instance from a
1556 <     * stream (i.e., deserializes it).
3232 >     * Reconstitutes the instance from a stream (that is, deserializes it).
3233       * @param s the stream
3234       */
3235 <    @SuppressWarnings("unchecked")
3236 <    private void readObject(java.io.ObjectInputStream s)
3237 <            throws java.io.IOException, ClassNotFoundException {
3235 >    @SuppressWarnings("unchecked") private void readObject
3236 >        (java.io.ObjectInputStream s)
3237 >        throws java.io.IOException, ClassNotFoundException {
3238          s.defaultReadObject();
1563        // find load factor in a segment, if one exists
1564        if (segments != null && segments.length != 0)
1565            this.loadFactor = segments[0].loadFactor;
1566        else
1567            this.loadFactor = DEFAULT_LOAD_FACTOR;
1568        this.initCap = DEFAULT_CAPACITY;
1569        LongAdder ct = new LongAdder(); // force final field write
1570        UNSAFE.putObjectVolatile(this, counterOffset, ct);
3239          this.segments = null; // unneeded
3240  
3241 <        // Read the keys and values, and put the mappings in the table
3241 >        // Create all nodes, then place in table once size is known
3242 >        long size = 0L;
3243 >        Node<V> p = null;
3244          for (;;) {
3245 <            K key = (K) s.readObject();
3246 <            V value = (V) s.readObject();
3247 <            if (key == null)
3245 >            K k = (K) s.readObject();
3246 >            V v = (V) s.readObject();
3247 >            if (k != null && v != null) {
3248 >                int h = spread(k.hashCode());
3249 >                p = new Node<V>(h, k, v, p);
3250 >                ++size;
3251 >            }
3252 >            else
3253                  break;
3254 <            put(key, value);
3254 >        }
3255 >        if (p != null) {
3256 >            boolean init = false;
3257 >            int n;
3258 >            if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
3259 >                n = MAXIMUM_CAPACITY;
3260 >            else {
3261 >                int sz = (int)size;
3262 >                n = tableSizeFor(sz + (sz >>> 1) + 1);
3263 >            }
3264 >            int sc = sizeCtl;
3265 >            boolean collide = false;
3266 >            if (n > sc &&
3267 >                U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
3268 >                try {
3269 >                    if (table == null) {
3270 >                        init = true;
3271 >                        @SuppressWarnings("rawtypes") Node[] rt = new Node[n];
3272 >                        Node<V>[] tab = (Node<V>[])rt;
3273 >                        int mask = n - 1;
3274 >                        while (p != null) {
3275 >                            int j = p.hash & mask;
3276 >                            Node<V> next = p.next;
3277 >                            Node<V> q = p.next = tabAt(tab, j);
3278 >                            setTabAt(tab, j, p);
3279 >                            if (!collide && q != null && q.hash == p.hash)
3280 >                                collide = true;
3281 >                            p = next;
3282 >                        }
3283 >                        table = tab;
3284 >                        addCount(size, -1);
3285 >                        sc = n - (n >>> 2);
3286 >                    }
3287 >                } finally {
3288 >                    sizeCtl = sc;
3289 >                }
3290 >                if (collide) { // rescan and convert to TreeBins
3291 >                    Node<V>[] tab = table;
3292 >                    for (int i = 0; i < tab.length; ++i) {
3293 >                        int c = 0;
3294 >                        for (Node<V> e = tabAt(tab, i); e != null; e = e.next) {
3295 >                            if (++c > TREE_THRESHOLD &&
3296 >                                (e.key instanceof Comparable)) {
3297 >                                replaceWithTreeBin(tab, i, e.key);
3298 >                                break;
3299 >                            }
3300 >                        }
3301 >                    }
3302 >                }
3303 >            }
3304 >            if (!init) { // Can only happen if unsafely published.
3305 >                while (p != null) {
3306 >                    internalPut((K)p.key, p.val, false);
3307 >                    p = p.next;
3308 >                }
3309 >            }
3310 >        }
3311 >    }
3312 >
3313 >    // -------------------------------------------------------
3314 >
3315 >    // Sams
3316 >    /** Interface describing a void action of one argument */
3317 >    public interface Action<A> { void apply(A a); }
3318 >    /** Interface describing a void action of two arguments */
3319 >    public interface BiAction<A,B> { void apply(A a, B b); }
3320 >    /** Interface describing a function of one argument */
3321 >    public interface Fun<A,T> { T apply(A a); }
3322 >    /** Interface describing a function of two arguments */
3323 >    public interface BiFun<A,B,T> { T apply(A a, B b); }
3324 >    /** Interface describing a function of no arguments */
3325 >    public interface Generator<T> { T apply(); }
3326 >    /** Interface describing a function mapping its argument to a double */
3327 >    public interface ObjectToDouble<A> { double apply(A a); }
3328 >    /** Interface describing a function mapping its argument to a long */
3329 >    public interface ObjectToLong<A> { long apply(A a); }
3330 >    /** Interface describing a function mapping its argument to an int */
3331 >    public interface ObjectToInt<A> {int apply(A a); }
3332 >    /** Interface describing a function mapping two arguments to a double */
3333 >    public interface ObjectByObjectToDouble<A,B> { double apply(A a, B b); }
3334 >    /** Interface describing a function mapping two arguments to a long */
3335 >    public interface ObjectByObjectToLong<A,B> { long apply(A a, B b); }
3336 >    /** Interface describing a function mapping two arguments to an int */
3337 >    public interface ObjectByObjectToInt<A,B> {int apply(A a, B b); }
3338 >    /** Interface describing a function mapping a double to a double */
3339 >    public interface DoubleToDouble { double apply(double a); }
3340 >    /** Interface describing a function mapping a long to a long */
3341 >    public interface LongToLong { long apply(long a); }
3342 >    /** Interface describing a function mapping an int to an int */
3343 >    public interface IntToInt { int apply(int a); }
3344 >    /** Interface describing a function mapping two doubles to a double */
3345 >    public interface DoubleByDoubleToDouble { double apply(double a, double b); }
3346 >    /** Interface describing a function mapping two longs to a long */
3347 >    public interface LongByLongToLong { long apply(long a, long b); }
3348 >    /** Interface describing a function mapping two ints to an int */
3349 >    public interface IntByIntToInt { int apply(int a, int b); }
3350 >
3351 >
3352 >    // -------------------------------------------------------
3353 >
3354 >    // Sequential bulk operations
3355 >
3356 >    /**
3357 >     * Performs the given action for each (key, value).
3358 >     *
3359 >     * @param action the action
3360 >     */
3361 >    @SuppressWarnings("unchecked") public void forEachSequentially
3362 >        (BiAction<K,V> action) {
3363 >        if (action == null) throw new NullPointerException();
3364 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3365 >        V v;
3366 >        while ((v = it.advance()) != null)
3367 >            action.apply((K)it.nextKey, v);
3368 >    }
3369 >
3370 >    /**
3371 >     * Performs the given action for each non-null transformation
3372 >     * of each (key, value).
3373 >     *
3374 >     * @param transformer a function returning the transformation
3375 >     * for an element, or null if there is no transformation (in
3376 >     * which case the action is not applied)
3377 >     * @param action the action
3378 >     */
3379 >    @SuppressWarnings("unchecked") public <U> void forEachSequentially
3380 >        (BiFun<? super K, ? super V, ? extends U> transformer,
3381 >         Action<U> action) {
3382 >        if (transformer == null || action == null)
3383 >            throw new NullPointerException();
3384 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3385 >        V v; U u;
3386 >        while ((v = it.advance()) != null) {
3387 >            if ((u = transformer.apply((K)it.nextKey, v)) != null)
3388 >                action.apply(u);
3389 >        }
3390 >    }
3391 >
3392 >    /**
3393 >     * Returns a non-null result from applying the given search
3394 >     * function on each (key, value), or null if none.
3395 >     *
3396 >     * @param searchFunction a function returning a non-null
3397 >     * result on success, else null
3398 >     * @return a non-null result from applying the given search
3399 >     * function on each (key, value), or null if none
3400 >     */
3401 >    @SuppressWarnings("unchecked") public <U> U searchSequentially
3402 >        (BiFun<? super K, ? super V, ? extends U> searchFunction) {
3403 >        if (searchFunction == null) throw new NullPointerException();
3404 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3405 >        V v; U u;
3406 >        while ((v = it.advance()) != null) {
3407 >            if ((u = searchFunction.apply((K)it.nextKey, v)) != null)
3408 >                return u;
3409 >        }
3410 >        return null;
3411 >    }
3412 >
3413 >    /**
3414 >     * Returns the result of accumulating the given transformation
3415 >     * of all (key, value) pairs using the given reducer to
3416 >     * combine values, or null if none.
3417 >     *
3418 >     * @param transformer a function returning the transformation
3419 >     * for an element, or null if there is no transformation (in
3420 >     * which case it is not combined)
3421 >     * @param reducer a commutative associative combining function
3422 >     * @return the result of accumulating the given transformation
3423 >     * of all (key, value) pairs
3424 >     */
3425 >    @SuppressWarnings("unchecked") public <U> U reduceSequentially
3426 >        (BiFun<? super K, ? super V, ? extends U> transformer,
3427 >         BiFun<? super U, ? super U, ? extends U> reducer) {
3428 >        if (transformer == null || reducer == null)
3429 >            throw new NullPointerException();
3430 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3431 >        U r = null, u; V v;
3432 >        while ((v = it.advance()) != null) {
3433 >            if ((u = transformer.apply((K)it.nextKey, v)) != null)
3434 >                r = (r == null) ? u : reducer.apply(r, u);
3435 >        }
3436 >        return r;
3437 >    }
3438 >
3439 >    /**
3440 >     * Returns the result of accumulating the given transformation
3441 >     * of all (key, value) pairs using the given reducer to
3442 >     * combine values, and the given basis as an identity value.
3443 >     *
3444 >     * @param transformer a function returning the transformation
3445 >     * for an element
3446 >     * @param basis the identity (initial default value) for the reduction
3447 >     * @param reducer a commutative associative combining function
3448 >     * @return the result of accumulating the given transformation
3449 >     * of all (key, value) pairs
3450 >     */
3451 >    @SuppressWarnings("unchecked") public double reduceToDoubleSequentially
3452 >        (ObjectByObjectToDouble<? super K, ? super V> transformer,
3453 >         double basis,
3454 >         DoubleByDoubleToDouble reducer) {
3455 >        if (transformer == null || reducer == null)
3456 >            throw new NullPointerException();
3457 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3458 >        double r = basis; V v;
3459 >        while ((v = it.advance()) != null)
3460 >            r = reducer.apply(r, transformer.apply((K)it.nextKey, v));
3461 >        return r;
3462 >    }
3463 >
3464 >    /**
3465 >     * Returns the result of accumulating the given transformation
3466 >     * of all (key, value) pairs using the given reducer to
3467 >     * combine values, and the given basis as an identity value.
3468 >     *
3469 >     * @param transformer a function returning the transformation
3470 >     * for an element
3471 >     * @param basis the identity (initial default value) for the reduction
3472 >     * @param reducer a commutative associative combining function
3473 >     * @return the result of accumulating the given transformation
3474 >     * of all (key, value) pairs
3475 >     */
3476 >    @SuppressWarnings("unchecked") public long reduceToLongSequentially
3477 >        (ObjectByObjectToLong<? super K, ? super V> transformer,
3478 >         long basis,
3479 >         LongByLongToLong reducer) {
3480 >        if (transformer == null || reducer == null)
3481 >            throw new NullPointerException();
3482 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3483 >        long r = basis; V v;
3484 >        while ((v = it.advance()) != null)
3485 >            r = reducer.apply(r, transformer.apply((K)it.nextKey, v));
3486 >        return r;
3487 >    }
3488 >
3489 >    /**
3490 >     * Returns the result of accumulating the given transformation
3491 >     * of all (key, value) pairs using the given reducer to
3492 >     * combine values, and the given basis as an identity value.
3493 >     *
3494 >     * @param transformer a function returning the transformation
3495 >     * for an element
3496 >     * @param basis the identity (initial default value) for the reduction
3497 >     * @param reducer a commutative associative combining function
3498 >     * @return the result of accumulating the given transformation
3499 >     * of all (key, value) pairs
3500 >     */
3501 >    @SuppressWarnings("unchecked") public int reduceToIntSequentially
3502 >        (ObjectByObjectToInt<? super K, ? super V> transformer,
3503 >         int basis,
3504 >         IntByIntToInt reducer) {
3505 >        if (transformer == null || reducer == null)
3506 >            throw new NullPointerException();
3507 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3508 >        int r = basis; V v;
3509 >        while ((v = it.advance()) != null)
3510 >            r = reducer.apply(r, transformer.apply((K)it.nextKey, v));
3511 >        return r;
3512 >    }
3513 >
3514 >    /**
3515 >     * Performs the given action for each key.
3516 >     *
3517 >     * @param action the action
3518 >     */
3519 >    @SuppressWarnings("unchecked") public void forEachKeySequentially
3520 >        (Action<K> action) {
3521 >        if (action == null) throw new NullPointerException();
3522 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3523 >        while (it.advance() != null)
3524 >            action.apply((K)it.nextKey);
3525 >    }
3526 >
3527 >    /**
3528 >     * Performs the given action for each non-null transformation
3529 >     * of each key.
3530 >     *
3531 >     * @param transformer a function returning the transformation
3532 >     * for an element, or null if there is no transformation (in
3533 >     * which case the action is not applied)
3534 >     * @param action the action
3535 >     */
3536 >    @SuppressWarnings("unchecked") public <U> void forEachKeySequentially
3537 >        (Fun<? super K, ? extends U> transformer,
3538 >         Action<U> action) {
3539 >        if (transformer == null || action == null)
3540 >            throw new NullPointerException();
3541 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3542 >        U u;
3543 >        while (it.advance() != null) {
3544 >            if ((u = transformer.apply((K)it.nextKey)) != null)
3545 >                action.apply(u);
3546 >        }
3547 >        ForkJoinTasks.forEachKey
3548 >            (this, transformer, action).invoke();
3549 >    }
3550 >
3551 >    /**
3552 >     * Returns a non-null result from applying the given search
3553 >     * function on each key, or null if none.
3554 >     *
3555 >     * @param searchFunction a function returning a non-null
3556 >     * result on success, else null
3557 >     * @return a non-null result from applying the given search
3558 >     * function on each key, or null if none
3559 >     */
3560 >    @SuppressWarnings("unchecked") public <U> U searchKeysSequentially
3561 >        (Fun<? super K, ? extends U> searchFunction) {
3562 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3563 >        U u;
3564 >        while (it.advance() != null) {
3565 >            if ((u = searchFunction.apply((K)it.nextKey)) != null)
3566 >                return u;
3567 >        }
3568 >        return null;
3569 >    }
3570 >
3571 >    /**
3572 >     * Returns the result of accumulating all keys using the given
3573 >     * reducer to combine values, or null if none.
3574 >     *
3575 >     * @param reducer a commutative associative combining function
3576 >     * @return the result of accumulating all keys using the given
3577 >     * reducer to combine values, or null if none
3578 >     */
3579 >    @SuppressWarnings("unchecked") public K reduceKeysSequentially
3580 >        (BiFun<? super K, ? super K, ? extends K> reducer) {
3581 >        if (reducer == null) throw new NullPointerException();
3582 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3583 >        K r = null;
3584 >        while (it.advance() != null) {
3585 >            K u = (K)it.nextKey;
3586 >            r = (r == null) ? u : reducer.apply(r, u);
3587 >        }
3588 >        return r;
3589 >    }
3590 >
3591 >    /**
3592 >     * Returns the result of accumulating the given transformation
3593 >     * of all keys using the given reducer to combine values, or
3594 >     * null if none.
3595 >     *
3596 >     * @param transformer a function returning the transformation
3597 >     * for an element, or null if there is no transformation (in
3598 >     * which case it is not combined)
3599 >     * @param reducer a commutative associative combining function
3600 >     * @return the result of accumulating the given transformation
3601 >     * of all keys
3602 >     */
3603 >    @SuppressWarnings("unchecked") public <U> U reduceKeysSequentially
3604 >        (Fun<? super K, ? extends U> transformer,
3605 >         BiFun<? super U, ? super U, ? extends U> reducer) {
3606 >        if (transformer == null || reducer == null)
3607 >            throw new NullPointerException();
3608 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3609 >        U r = null, u;
3610 >        while (it.advance() != null) {
3611 >            if ((u = transformer.apply((K)it.nextKey)) != null)
3612 >                r = (r == null) ? u : reducer.apply(r, u);
3613 >        }
3614 >        return r;
3615 >    }
3616 >
3617 >    /**
3618 >     * Returns the result of accumulating the given transformation
3619 >     * of all keys using the given reducer to combine values, and
3620 >     * the given basis as an identity value.
3621 >     *
3622 >     * @param transformer a function returning the transformation
3623 >     * for an element
3624 >     * @param basis the identity (initial default value) for the reduction
3625 >     * @param reducer a commutative associative combining function
3626 >     * @return  the result of accumulating the given transformation
3627 >     * of all keys
3628 >     */
3629 >    @SuppressWarnings("unchecked") public double reduceKeysToDoubleSequentially
3630 >        (ObjectToDouble<? super K> transformer,
3631 >         double basis,
3632 >         DoubleByDoubleToDouble reducer) {
3633 >        if (transformer == null || reducer == null)
3634 >            throw new NullPointerException();
3635 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3636 >        double r = basis;
3637 >        while (it.advance() != null)
3638 >            r = reducer.apply(r, transformer.apply((K)it.nextKey));
3639 >        return r;
3640 >    }
3641 >
3642 >    /**
3643 >     * Returns the result of accumulating the given transformation
3644 >     * of all keys using the given reducer to combine values, and
3645 >     * the given basis as an identity value.
3646 >     *
3647 >     * @param transformer a function returning the transformation
3648 >     * for an element
3649 >     * @param basis the identity (initial default value) for the reduction
3650 >     * @param reducer a commutative associative combining function
3651 >     * @return the result of accumulating the given transformation
3652 >     * of all keys
3653 >     */
3654 >    @SuppressWarnings("unchecked") public long reduceKeysToLongSequentially
3655 >        (ObjectToLong<? super K> transformer,
3656 >         long basis,
3657 >         LongByLongToLong reducer) {
3658 >        if (transformer == null || reducer == null)
3659 >            throw new NullPointerException();
3660 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3661 >        long r = basis;
3662 >        while (it.advance() != null)
3663 >            r = reducer.apply(r, transformer.apply((K)it.nextKey));
3664 >        return r;
3665 >    }
3666 >
3667 >    /**
3668 >     * Returns the result of accumulating the given transformation
3669 >     * of all keys using the given reducer to combine values, and
3670 >     * the given basis as an identity value.
3671 >     *
3672 >     * @param transformer a function returning the transformation
3673 >     * for an element
3674 >     * @param basis the identity (initial default value) for the reduction
3675 >     * @param reducer a commutative associative combining function
3676 >     * @return the result of accumulating the given transformation
3677 >     * of all keys
3678 >     */
3679 >    @SuppressWarnings("unchecked") public int reduceKeysToIntSequentially
3680 >        (ObjectToInt<? super K> transformer,
3681 >         int basis,
3682 >         IntByIntToInt reducer) {
3683 >        if (transformer == null || reducer == null)
3684 >            throw new NullPointerException();
3685 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3686 >        int r = basis;
3687 >        while (it.advance() != null)
3688 >            r = reducer.apply(r, transformer.apply((K)it.nextKey));
3689 >        return r;
3690 >    }
3691 >
3692 >    /**
3693 >     * Performs the given action for each value.
3694 >     *
3695 >     * @param action the action
3696 >     */
3697 >    public void forEachValueSequentially(Action<V> action) {
3698 >        if (action == null) throw new NullPointerException();
3699 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3700 >        V v;
3701 >        while ((v = it.advance()) != null)
3702 >            action.apply(v);
3703 >    }
3704 >
3705 >    /**
3706 >     * Performs the given action for each non-null transformation
3707 >     * of each value.
3708 >     *
3709 >     * @param transformer a function returning the transformation
3710 >     * for an element, or null if there is no transformation (in
3711 >     * which case the action is not applied)
3712 >     */
3713 >    public <U> void forEachValueSequentially
3714 >        (Fun<? super V, ? extends U> transformer,
3715 >         Action<U> action) {
3716 >        if (transformer == null || action == null)
3717 >            throw new NullPointerException();
3718 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3719 >        V v; U u;
3720 >        while ((v = it.advance()) != null) {
3721 >            if ((u = transformer.apply(v)) != null)
3722 >                action.apply(u);
3723 >        }
3724 >    }
3725 >
3726 >    /**
3727 >     * Returns a non-null result from applying the given search
3728 >     * function on each value, or null if none.
3729 >     *
3730 >     * @param searchFunction a function returning a non-null
3731 >     * result on success, else null
3732 >     * @return a non-null result from applying the given search
3733 >     * function on each value, or null if none
3734 >     */
3735 >    public <U> U searchValuesSequentially
3736 >        (Fun<? super V, ? extends U> searchFunction) {
3737 >        if (searchFunction == null) throw new NullPointerException();
3738 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3739 >        V v; U u;
3740 >        while ((v = it.advance()) != null) {
3741 >            if ((u = searchFunction.apply(v)) != null)
3742 >                return u;
3743 >        }
3744 >        return null;
3745 >    }
3746 >
3747 >    /**
3748 >     * Returns the result of accumulating all values using the
3749 >     * given reducer to combine values, or null if none.
3750 >     *
3751 >     * @param reducer a commutative associative combining function
3752 >     * @return  the result of accumulating all values
3753 >     */
3754 >    public V reduceValuesSequentially
3755 >        (BiFun<? super V, ? super V, ? extends V> reducer) {
3756 >        if (reducer == null) throw new NullPointerException();
3757 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3758 >        V r = null; V v;
3759 >        while ((v = it.advance()) != null)
3760 >            r = (r == null) ? v : reducer.apply(r, v);
3761 >        return r;
3762 >    }
3763 >
3764 >    /**
3765 >     * Returns the result of accumulating the given transformation
3766 >     * of all values using the given reducer to combine values, or
3767 >     * null if none.
3768 >     *
3769 >     * @param transformer a function returning the transformation
3770 >     * for an element, or null if there is no transformation (in
3771 >     * which case it is not combined)
3772 >     * @param reducer a commutative associative combining function
3773 >     * @return the result of accumulating the given transformation
3774 >     * of all values
3775 >     */
3776 >    public <U> U reduceValuesSequentially
3777 >        (Fun<? super V, ? extends U> transformer,
3778 >         BiFun<? super U, ? super U, ? extends U> reducer) {
3779 >        if (transformer == null || reducer == null)
3780 >            throw new NullPointerException();
3781 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3782 >        U r = null, u; V v;
3783 >        while ((v = it.advance()) != null) {
3784 >            if ((u = transformer.apply(v)) != null)
3785 >                r = (r == null) ? u : reducer.apply(r, u);
3786 >        }
3787 >        return r;
3788 >    }
3789 >
3790 >    /**
3791 >     * Returns the result of accumulating the given transformation
3792 >     * of all values using the given reducer to combine values,
3793 >     * and the given basis as an identity value.
3794 >     *
3795 >     * @param transformer a function returning the transformation
3796 >     * for an element
3797 >     * @param basis the identity (initial default value) for the reduction
3798 >     * @param reducer a commutative associative combining function
3799 >     * @return the result of accumulating the given transformation
3800 >     * of all values
3801 >     */
3802 >    public double reduceValuesToDoubleSequentially
3803 >        (ObjectToDouble<? super V> transformer,
3804 >         double basis,
3805 >         DoubleByDoubleToDouble reducer) {
3806 >        if (transformer == null || reducer == null)
3807 >            throw new NullPointerException();
3808 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3809 >        double r = basis; V v;
3810 >        while ((v = it.advance()) != null)
3811 >            r = reducer.apply(r, transformer.apply(v));
3812 >        return r;
3813 >    }
3814 >
3815 >    /**
3816 >     * Returns the result of accumulating the given transformation
3817 >     * of all values using the given reducer to combine values,
3818 >     * and the given basis as an identity value.
3819 >     *
3820 >     * @param transformer a function returning the transformation
3821 >     * for an element
3822 >     * @param basis the identity (initial default value) for the reduction
3823 >     * @param reducer a commutative associative combining function
3824 >     * @return the result of accumulating the given transformation
3825 >     * of all values
3826 >     */
3827 >    public long reduceValuesToLongSequentially
3828 >        (ObjectToLong<? super V> transformer,
3829 >         long basis,
3830 >         LongByLongToLong reducer) {
3831 >        if (transformer == null || reducer == null)
3832 >            throw new NullPointerException();
3833 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3834 >        long r = basis; V v;
3835 >        while ((v = it.advance()) != null)
3836 >            r = reducer.apply(r, transformer.apply(v));
3837 >        return r;
3838 >    }
3839 >
3840 >    /**
3841 >     * Returns the result of accumulating the given transformation
3842 >     * of all values using the given reducer to combine values,
3843 >     * and the given basis as an identity value.
3844 >     *
3845 >     * @param transformer a function returning the transformation
3846 >     * for an element
3847 >     * @param basis the identity (initial default value) for the reduction
3848 >     * @param reducer a commutative associative combining function
3849 >     * @return the result of accumulating the given transformation
3850 >     * of all values
3851 >     */
3852 >    public int reduceValuesToIntSequentially
3853 >        (ObjectToInt<? super V> transformer,
3854 >         int basis,
3855 >         IntByIntToInt reducer) {
3856 >        if (transformer == null || reducer == null)
3857 >            throw new NullPointerException();
3858 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3859 >        int r = basis; V v;
3860 >        while ((v = it.advance()) != null)
3861 >            r = reducer.apply(r, transformer.apply(v));
3862 >        return r;
3863 >    }
3864 >
3865 >    /**
3866 >     * Performs the given action for each entry.
3867 >     *
3868 >     * @param action the action
3869 >     */
3870 >    @SuppressWarnings("unchecked") public void forEachEntrySequentially
3871 >        (Action<Map.Entry<K,V>> action) {
3872 >        if (action == null) throw new NullPointerException();
3873 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3874 >        V v;
3875 >        while ((v = it.advance()) != null)
3876 >            action.apply(entryFor((K)it.nextKey, v));
3877 >    }
3878 >
3879 >    /**
3880 >     * Performs the given action for each non-null transformation
3881 >     * of each entry.
3882 >     *
3883 >     * @param transformer a function returning the transformation
3884 >     * for an element, or null if there is no transformation (in
3885 >     * which case the action is not applied)
3886 >     * @param action the action
3887 >     */
3888 >    @SuppressWarnings("unchecked") public <U> void forEachEntrySequentially
3889 >        (Fun<Map.Entry<K,V>, ? extends U> transformer,
3890 >         Action<U> action) {
3891 >        if (transformer == null || action == null)
3892 >            throw new NullPointerException();
3893 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3894 >        V v; U u;
3895 >        while ((v = it.advance()) != null) {
3896 >            if ((u = transformer.apply(entryFor((K)it.nextKey, v))) != null)
3897 >                action.apply(u);
3898 >        }
3899 >    }
3900 >
3901 >    /**
3902 >     * Returns a non-null result from applying the given search
3903 >     * function on each entry, or null if none.
3904 >     *
3905 >     * @param searchFunction a function returning a non-null
3906 >     * result on success, else null
3907 >     * @return a non-null result from applying the given search
3908 >     * function on each entry, or null if none
3909 >     */
3910 >    @SuppressWarnings("unchecked") public <U> U searchEntriesSequentially
3911 >        (Fun<Map.Entry<K,V>, ? extends U> searchFunction) {
3912 >        if (searchFunction == null) throw new NullPointerException();
3913 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3914 >        V v; U u;
3915 >        while ((v = it.advance()) != null) {
3916 >            if ((u = searchFunction.apply(entryFor((K)it.nextKey, v))) != null)
3917 >                return u;
3918 >        }
3919 >        return null;
3920 >    }
3921 >
3922 >    /**
3923 >     * Returns the result of accumulating all entries using the
3924 >     * given reducer to combine values, or null if none.
3925 >     *
3926 >     * @param reducer a commutative associative combining function
3927 >     * @return the result of accumulating all entries
3928 >     */
3929 >    @SuppressWarnings("unchecked") public Map.Entry<K,V> reduceEntriesSequentially
3930 >        (BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
3931 >        if (reducer == null) throw new NullPointerException();
3932 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3933 >        Map.Entry<K,V> r = null; V v;
3934 >        while ((v = it.advance()) != null) {
3935 >            Map.Entry<K,V> u = entryFor((K)it.nextKey, v);
3936 >            r = (r == null) ? u : reducer.apply(r, u);
3937 >        }
3938 >        return r;
3939 >    }
3940 >
3941 >    /**
3942 >     * Returns the result of accumulating the given transformation
3943 >     * of all entries using the given reducer to combine values,
3944 >     * or null if none.
3945 >     *
3946 >     * @param transformer a function returning the transformation
3947 >     * for an element, or null if there is no transformation (in
3948 >     * which case it is not combined)
3949 >     * @param reducer a commutative associative combining function
3950 >     * @return the result of accumulating the given transformation
3951 >     * of all entries
3952 >     */
3953 >    @SuppressWarnings("unchecked") public <U> U reduceEntriesSequentially
3954 >        (Fun<Map.Entry<K,V>, ? extends U> transformer,
3955 >         BiFun<? super U, ? super U, ? extends U> reducer) {
3956 >        if (transformer == null || reducer == null)
3957 >            throw new NullPointerException();
3958 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3959 >        U r = null, u; V v;
3960 >        while ((v = it.advance()) != null) {
3961 >            if ((u = transformer.apply(entryFor((K)it.nextKey, v))) != null)
3962 >                r = (r == null) ? u : reducer.apply(r, u);
3963 >        }
3964 >        return r;
3965 >    }
3966 >
3967 >    /**
3968 >     * Returns the result of accumulating the given transformation
3969 >     * of all entries using the given reducer to combine values,
3970 >     * and the given basis as an identity value.
3971 >     *
3972 >     * @param transformer a function returning the transformation
3973 >     * for an element
3974 >     * @param basis the identity (initial default value) for the reduction
3975 >     * @param reducer a commutative associative combining function
3976 >     * @return the result of accumulating the given transformation
3977 >     * of all entries
3978 >     */
3979 >    @SuppressWarnings("unchecked") public double reduceEntriesToDoubleSequentially
3980 >        (ObjectToDouble<Map.Entry<K,V>> transformer,
3981 >         double basis,
3982 >         DoubleByDoubleToDouble reducer) {
3983 >        if (transformer == null || reducer == null)
3984 >            throw new NullPointerException();
3985 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3986 >        double r = basis; V v;
3987 >        while ((v = it.advance()) != null)
3988 >            r = reducer.apply(r, transformer.apply(entryFor((K)it.nextKey, v)));
3989 >        return r;
3990 >    }
3991 >
3992 >    /**
3993 >     * Returns the result of accumulating the given transformation
3994 >     * of all entries using the given reducer to combine values,
3995 >     * and the given basis as an identity value.
3996 >     *
3997 >     * @param transformer a function returning the transformation
3998 >     * for an element
3999 >     * @param basis the identity (initial default value) for the reduction
4000 >     * @param reducer a commutative associative combining function
4001 >     * @return  the result of accumulating the given transformation
4002 >     * of all entries
4003 >     */
4004 >    @SuppressWarnings("unchecked") public long reduceEntriesToLongSequentially
4005 >        (ObjectToLong<Map.Entry<K,V>> transformer,
4006 >         long basis,
4007 >         LongByLongToLong reducer) {
4008 >        if (transformer == null || reducer == null)
4009 >            throw new NullPointerException();
4010 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
4011 >        long r = basis; V v;
4012 >        while ((v = it.advance()) != null)
4013 >            r = reducer.apply(r, transformer.apply(entryFor((K)it.nextKey, v)));
4014 >        return r;
4015 >    }
4016 >
4017 >    /**
4018 >     * Returns the result of accumulating the given transformation
4019 >     * of all entries using the given reducer to combine values,
4020 >     * and the given basis as an identity value.
4021 >     *
4022 >     * @param transformer a function returning the transformation
4023 >     * for an element
4024 >     * @param basis the identity (initial default value) for the reduction
4025 >     * @param reducer a commutative associative combining function
4026 >     * @return the result of accumulating the given transformation
4027 >     * of all entries
4028 >     */
4029 >    @SuppressWarnings("unchecked") public int reduceEntriesToIntSequentially
4030 >        (ObjectToInt<Map.Entry<K,V>> transformer,
4031 >         int basis,
4032 >         IntByIntToInt reducer) {
4033 >        if (transformer == null || reducer == null)
4034 >            throw new NullPointerException();
4035 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
4036 >        int r = basis; V v;
4037 >        while ((v = it.advance()) != null)
4038 >            r = reducer.apply(r, transformer.apply(entryFor((K)it.nextKey, v)));
4039 >        return r;
4040 >    }
4041 >
4042 >    // Parallel bulk operations
4043 >
4044 >    /**
4045 >     * Performs the given action for each (key, value).
4046 >     *
4047 >     * @param action the action
4048 >     */
4049 >    public void forEachInParallel(BiAction<K,V> action) {
4050 >        ForkJoinTasks.forEach
4051 >            (this, action).invoke();
4052 >    }
4053 >
4054 >    /**
4055 >     * Performs the given action for each non-null transformation
4056 >     * of each (key, value).
4057 >     *
4058 >     * @param transformer a function returning the transformation
4059 >     * for an element, or null if there is no transformation (in
4060 >     * which case the action is not applied)
4061 >     * @param action the action
4062 >     */
4063 >    public <U> void forEachInParallel
4064 >        (BiFun<? super K, ? super V, ? extends U> transformer,
4065 >                            Action<U> action) {
4066 >        ForkJoinTasks.forEach
4067 >            (this, transformer, action).invoke();
4068 >    }
4069 >
4070 >    /**
4071 >     * Returns a non-null result from applying the given search
4072 >     * function on each (key, value), or null if none.  Upon
4073 >     * success, further element processing is suppressed and the
4074 >     * results of any other parallel invocations of the search
4075 >     * function are ignored.
4076 >     *
4077 >     * @param searchFunction a function returning a non-null
4078 >     * result on success, else null
4079 >     * @return a non-null result from applying the given search
4080 >     * function on each (key, value), or null if none
4081 >     */
4082 >    public <U> U searchInParallel
4083 >        (BiFun<? super K, ? super V, ? extends U> searchFunction) {
4084 >        return ForkJoinTasks.search
4085 >            (this, searchFunction).invoke();
4086 >    }
4087 >
4088 >    /**
4089 >     * Returns the result of accumulating the given transformation
4090 >     * of all (key, value) pairs using the given reducer to
4091 >     * combine values, 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 (key, value) pairs
4099 >     */
4100 >    public <U> U reduceInParallel
4101 >        (BiFun<? super K, ? super V, ? extends U> transformer,
4102 >         BiFun<? super U, ? super U, ? extends U> reducer) {
4103 >        return ForkJoinTasks.reduce
4104 >            (this, transformer, reducer).invoke();
4105 >    }
4106 >
4107 >    /**
4108 >     * Returns the result of accumulating the given transformation
4109 >     * of all (key, value) pairs using the given reducer to
4110 >     * combine values, and the given basis as an identity value.
4111 >     *
4112 >     * @param transformer a function returning the transformation
4113 >     * for an element
4114 >     * @param basis the identity (initial default value) for the reduction
4115 >     * @param reducer a commutative associative combining function
4116 >     * @return the result of accumulating the given transformation
4117 >     * of all (key, value) pairs
4118 >     */
4119 >    public double reduceToDoubleInParallel
4120 >        (ObjectByObjectToDouble<? super K, ? super V> transformer,
4121 >         double basis,
4122 >         DoubleByDoubleToDouble reducer) {
4123 >        return ForkJoinTasks.reduceToDouble
4124 >            (this, transformer, basis, reducer).invoke();
4125 >    }
4126 >
4127 >    /**
4128 >     * Returns the result of accumulating the given transformation
4129 >     * of all (key, value) pairs using the given reducer to
4130 >     * combine values, and the given basis as an identity value.
4131 >     *
4132 >     * @param transformer a function returning the transformation
4133 >     * for an element
4134 >     * @param basis the identity (initial default value) for the reduction
4135 >     * @param reducer a commutative associative combining function
4136 >     * @return the result of accumulating the given transformation
4137 >     * of all (key, value) pairs
4138 >     */
4139 >    public long reduceToLongInParallel
4140 >        (ObjectByObjectToLong<? super K, ? super V> transformer,
4141 >         long basis,
4142 >         LongByLongToLong reducer) {
4143 >        return ForkJoinTasks.reduceToLong
4144 >            (this, transformer, basis, reducer).invoke();
4145 >    }
4146 >
4147 >    /**
4148 >     * Returns the result of accumulating the given transformation
4149 >     * of all (key, value) pairs using the given reducer to
4150 >     * combine values, and the given basis as an identity value.
4151 >     *
4152 >     * @param transformer a function returning the transformation
4153 >     * for an element
4154 >     * @param basis the identity (initial default value) for the reduction
4155 >     * @param reducer a commutative associative combining function
4156 >     * @return the result of accumulating the given transformation
4157 >     * of all (key, value) pairs
4158 >     */
4159 >    public int reduceToIntInParallel
4160 >        (ObjectByObjectToInt<? super K, ? super V> transformer,
4161 >         int basis,
4162 >         IntByIntToInt reducer) {
4163 >        return ForkJoinTasks.reduceToInt
4164 >            (this, transformer, basis, reducer).invoke();
4165 >    }
4166 >
4167 >    /**
4168 >     * Performs the given action for each key.
4169 >     *
4170 >     * @param action the action
4171 >     */
4172 >    public void forEachKeyInParallel(Action<K> action) {
4173 >        ForkJoinTasks.forEachKey
4174 >            (this, action).invoke();
4175 >    }
4176 >
4177 >    /**
4178 >     * Performs the given action for each non-null transformation
4179 >     * of each key.
4180 >     *
4181 >     * @param transformer a function returning the transformation
4182 >     * for an element, or null if there is no transformation (in
4183 >     * which case the action is not applied)
4184 >     * @param action the action
4185 >     */
4186 >    public <U> void forEachKeyInParallel
4187 >        (Fun<? super K, ? extends U> transformer,
4188 >         Action<U> action) {
4189 >        ForkJoinTasks.forEachKey
4190 >            (this, transformer, action).invoke();
4191 >    }
4192 >
4193 >    /**
4194 >     * Returns a non-null result from applying the given search
4195 >     * function on each key, or null if none. Upon success,
4196 >     * further element processing is suppressed and the results of
4197 >     * any other parallel invocations of the search function are
4198 >     * ignored.
4199 >     *
4200 >     * @param searchFunction a function returning a non-null
4201 >     * result on success, else null
4202 >     * @return a non-null result from applying the given search
4203 >     * function on each key, or null if none
4204 >     */
4205 >    public <U> U searchKeysInParallel
4206 >        (Fun<? super K, ? extends U> searchFunction) {
4207 >        return ForkJoinTasks.searchKeys
4208 >            (this, searchFunction).invoke();
4209 >    }
4210 >
4211 >    /**
4212 >     * Returns the result of accumulating all keys using the given
4213 >     * reducer to combine values, or null if none.
4214 >     *
4215 >     * @param reducer a commutative associative combining function
4216 >     * @return the result of accumulating all keys using the given
4217 >     * reducer to combine values, or null if none
4218 >     */
4219 >    public K reduceKeysInParallel
4220 >        (BiFun<? super K, ? super K, ? extends K> reducer) {
4221 >        return ForkJoinTasks.reduceKeys
4222 >            (this, reducer).invoke();
4223 >    }
4224 >
4225 >    /**
4226 >     * Returns the result of accumulating the given transformation
4227 >     * of all keys using the given reducer to combine values, or
4228 >     * null if none.
4229 >     *
4230 >     * @param transformer a function returning the transformation
4231 >     * for an element, or null if there is no transformation (in
4232 >     * which case it is not combined)
4233 >     * @param reducer a commutative associative combining function
4234 >     * @return the result of accumulating the given transformation
4235 >     * of all keys
4236 >     */
4237 >    public <U> U reduceKeysInParallel
4238 >        (Fun<? super K, ? extends U> transformer,
4239 >         BiFun<? super U, ? super U, ? extends U> reducer) {
4240 >        return ForkJoinTasks.reduceKeys
4241 >            (this, transformer, reducer).invoke();
4242 >    }
4243 >
4244 >    /**
4245 >     * Returns the result of accumulating the given transformation
4246 >     * of all keys using the given reducer to combine values, and
4247 >     * the given basis as an identity value.
4248 >     *
4249 >     * @param transformer a function returning the transformation
4250 >     * for an element
4251 >     * @param basis the identity (initial default value) for the reduction
4252 >     * @param reducer a commutative associative combining function
4253 >     * @return  the result of accumulating the given transformation
4254 >     * of all keys
4255 >     */
4256 >    public double reduceKeysToDoubleInParallel
4257 >        (ObjectToDouble<? super K> transformer,
4258 >         double basis,
4259 >         DoubleByDoubleToDouble reducer) {
4260 >        return ForkJoinTasks.reduceKeysToDouble
4261 >            (this, transformer, basis, reducer).invoke();
4262 >    }
4263 >
4264 >    /**
4265 >     * Returns the result of accumulating the given transformation
4266 >     * of all keys using the given reducer to combine values, and
4267 >     * the given basis as an identity value.
4268 >     *
4269 >     * @param transformer a function returning the transformation
4270 >     * for an element
4271 >     * @param basis the identity (initial default value) for the reduction
4272 >     * @param reducer a commutative associative combining function
4273 >     * @return the result of accumulating the given transformation
4274 >     * of all keys
4275 >     */
4276 >    public long reduceKeysToLongInParallel
4277 >        (ObjectToLong<? super K> transformer,
4278 >         long basis,
4279 >         LongByLongToLong reducer) {
4280 >        return ForkJoinTasks.reduceKeysToLong
4281 >            (this, transformer, basis, reducer).invoke();
4282 >    }
4283 >
4284 >    /**
4285 >     * Returns the result of accumulating the given transformation
4286 >     * of all keys using the given reducer to combine values, and
4287 >     * the given basis as an identity value.
4288 >     *
4289 >     * @param transformer a function returning the transformation
4290 >     * for an element
4291 >     * @param basis the identity (initial default value) for the reduction
4292 >     * @param reducer a commutative associative combining function
4293 >     * @return the result of accumulating the given transformation
4294 >     * of all keys
4295 >     */
4296 >    public int reduceKeysToIntInParallel
4297 >        (ObjectToInt<? super K> transformer,
4298 >         int basis,
4299 >         IntByIntToInt reducer) {
4300 >        return ForkJoinTasks.reduceKeysToInt
4301 >            (this, transformer, basis, reducer).invoke();
4302 >    }
4303 >
4304 >    /**
4305 >     * Performs the given action for each value.
4306 >     *
4307 >     * @param action the action
4308 >     */
4309 >    public void forEachValueInParallel(Action<V> action) {
4310 >        ForkJoinTasks.forEachValue
4311 >            (this, action).invoke();
4312 >    }
4313 >
4314 >    /**
4315 >     * Performs the given action for each non-null transformation
4316 >     * of each value.
4317 >     *
4318 >     * @param transformer a function returning the transformation
4319 >     * for an element, or null if there is no transformation (in
4320 >     * which case the action is not applied)
4321 >     */
4322 >    public <U> void forEachValueInParallel
4323 >        (Fun<? super V, ? extends U> transformer,
4324 >         Action<U> action) {
4325 >        ForkJoinTasks.forEachValue
4326 >            (this, transformer, action).invoke();
4327 >    }
4328 >
4329 >    /**
4330 >     * Returns a non-null result from applying the given search
4331 >     * function on each value, or null if none.  Upon success,
4332 >     * further element processing is suppressed and the results of
4333 >     * any other parallel invocations of the search function are
4334 >     * ignored.
4335 >     *
4336 >     * @param searchFunction a function returning a non-null
4337 >     * result on success, else null
4338 >     * @return a non-null result from applying the given search
4339 >     * function on each value, or null if none
4340 >     */
4341 >    public <U> U searchValuesInParallel
4342 >        (Fun<? super V, ? extends U> searchFunction) {
4343 >        return ForkJoinTasks.searchValues
4344 >            (this, searchFunction).invoke();
4345 >    }
4346 >
4347 >    /**
4348 >     * Returns the result of accumulating all values using the
4349 >     * given reducer to combine values, or null if none.
4350 >     *
4351 >     * @param reducer a commutative associative combining function
4352 >     * @return  the result of accumulating all values
4353 >     */
4354 >    public V reduceValuesInParallel
4355 >        (BiFun<? super V, ? super V, ? extends V> reducer) {
4356 >        return ForkJoinTasks.reduceValues
4357 >            (this, reducer).invoke();
4358 >    }
4359 >
4360 >    /**
4361 >     * Returns the result of accumulating the given transformation
4362 >     * of all values using the given reducer to combine values, or
4363 >     * null if none.
4364 >     *
4365 >     * @param transformer a function returning the transformation
4366 >     * for an element, or null if there is no transformation (in
4367 >     * which case it is not combined)
4368 >     * @param reducer a commutative associative combining function
4369 >     * @return the result of accumulating the given transformation
4370 >     * of all values
4371 >     */
4372 >    public <U> U reduceValuesInParallel
4373 >        (Fun<? super V, ? extends U> transformer,
4374 >         BiFun<? super U, ? super U, ? extends U> reducer) {
4375 >        return ForkJoinTasks.reduceValues
4376 >            (this, transformer, reducer).invoke();
4377 >    }
4378 >
4379 >    /**
4380 >     * Returns the result of accumulating the given transformation
4381 >     * of all values using the given reducer to combine values,
4382 >     * and the given basis as an identity value.
4383 >     *
4384 >     * @param transformer a function returning the transformation
4385 >     * for an element
4386 >     * @param basis the identity (initial default value) for the reduction
4387 >     * @param reducer a commutative associative combining function
4388 >     * @return the result of accumulating the given transformation
4389 >     * of all values
4390 >     */
4391 >    public double reduceValuesToDoubleInParallel
4392 >        (ObjectToDouble<? super V> transformer,
4393 >         double basis,
4394 >         DoubleByDoubleToDouble reducer) {
4395 >        return ForkJoinTasks.reduceValuesToDouble
4396 >            (this, transformer, basis, reducer).invoke();
4397 >    }
4398 >
4399 >    /**
4400 >     * Returns the result of accumulating the given transformation
4401 >     * of all values using the given reducer to combine values,
4402 >     * and the given basis as an identity value.
4403 >     *
4404 >     * @param transformer a function returning the transformation
4405 >     * for an element
4406 >     * @param basis the identity (initial default value) for the reduction
4407 >     * @param reducer a commutative associative combining function
4408 >     * @return the result of accumulating the given transformation
4409 >     * of all values
4410 >     */
4411 >    public long reduceValuesToLongInParallel
4412 >        (ObjectToLong<? super V> transformer,
4413 >         long basis,
4414 >         LongByLongToLong reducer) {
4415 >        return ForkJoinTasks.reduceValuesToLong
4416 >            (this, transformer, basis, reducer).invoke();
4417 >    }
4418 >
4419 >    /**
4420 >     * Returns the result of accumulating the given transformation
4421 >     * of all values using the given reducer to combine values,
4422 >     * and the given basis as an identity value.
4423 >     *
4424 >     * @param transformer a function returning the transformation
4425 >     * for an element
4426 >     * @param basis the identity (initial default value) for the reduction
4427 >     * @param reducer a commutative associative combining function
4428 >     * @return the result of accumulating the given transformation
4429 >     * of all values
4430 >     */
4431 >    public int reduceValuesToIntInParallel
4432 >        (ObjectToInt<? super V> transformer,
4433 >         int basis,
4434 >         IntByIntToInt reducer) {
4435 >        return ForkJoinTasks.reduceValuesToInt
4436 >            (this, transformer, basis, reducer).invoke();
4437 >    }
4438 >
4439 >    /**
4440 >     * Performs the given action for each entry.
4441 >     *
4442 >     * @param action the action
4443 >     */
4444 >    public void forEachEntryInParallel(Action<Map.Entry<K,V>> action) {
4445 >        ForkJoinTasks.forEachEntry
4446 >            (this, action).invoke();
4447 >    }
4448 >
4449 >    /**
4450 >     * Performs the given action for each non-null transformation
4451 >     * of each entry.
4452 >     *
4453 >     * @param transformer a function returning the transformation
4454 >     * for an element, or null if there is no transformation (in
4455 >     * which case the action is not applied)
4456 >     * @param action the action
4457 >     */
4458 >    public <U> void forEachEntryInParallel
4459 >        (Fun<Map.Entry<K,V>, ? extends U> transformer,
4460 >         Action<U> action) {
4461 >        ForkJoinTasks.forEachEntry
4462 >            (this, transformer, action).invoke();
4463 >    }
4464 >
4465 >    /**
4466 >     * Returns a non-null result from applying the given search
4467 >     * function on each entry, or null if none.  Upon success,
4468 >     * further element processing is suppressed and the results of
4469 >     * any other parallel invocations of the search function are
4470 >     * ignored.
4471 >     *
4472 >     * @param searchFunction a function returning a non-null
4473 >     * result on success, else null
4474 >     * @return a non-null result from applying the given search
4475 >     * function on each entry, or null if none
4476 >     */
4477 >    public <U> U searchEntriesInParallel
4478 >        (Fun<Map.Entry<K,V>, ? extends U> searchFunction) {
4479 >        return ForkJoinTasks.searchEntries
4480 >            (this, searchFunction).invoke();
4481 >    }
4482 >
4483 >    /**
4484 >     * Returns the result of accumulating all entries using the
4485 >     * given reducer to combine values, or null if none.
4486 >     *
4487 >     * @param reducer a commutative associative combining function
4488 >     * @return the result of accumulating all entries
4489 >     */
4490 >    public Map.Entry<K,V> reduceEntriesInParallel
4491 >        (BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4492 >        return ForkJoinTasks.reduceEntries
4493 >            (this, reducer).invoke();
4494 >    }
4495 >
4496 >    /**
4497 >     * Returns the result of accumulating the given transformation
4498 >     * of all entries using the given reducer to combine values,
4499 >     * or null if none.
4500 >     *
4501 >     * @param transformer a function returning the transformation
4502 >     * for an element, or null if there is no transformation (in
4503 >     * which case it is not combined)
4504 >     * @param reducer a commutative associative combining function
4505 >     * @return the result of accumulating the given transformation
4506 >     * of all entries
4507 >     */
4508 >    public <U> U reduceEntriesInParallel
4509 >        (Fun<Map.Entry<K,V>, ? extends U> transformer,
4510 >         BiFun<? super U, ? super U, ? extends U> reducer) {
4511 >        return ForkJoinTasks.reduceEntries
4512 >            (this, transformer, reducer).invoke();
4513 >    }
4514 >
4515 >    /**
4516 >     * Returns the result of accumulating the given transformation
4517 >     * of all entries using the given reducer to combine values,
4518 >     * and the given basis as an identity value.
4519 >     *
4520 >     * @param transformer a function returning the transformation
4521 >     * for an element
4522 >     * @param basis the identity (initial default value) for the reduction
4523 >     * @param reducer a commutative associative combining function
4524 >     * @return the result of accumulating the given transformation
4525 >     * of all entries
4526 >     */
4527 >    public double reduceEntriesToDoubleInParallel
4528 >        (ObjectToDouble<Map.Entry<K,V>> transformer,
4529 >         double basis,
4530 >         DoubleByDoubleToDouble reducer) {
4531 >        return ForkJoinTasks.reduceEntriesToDouble
4532 >            (this, transformer, basis, reducer).invoke();
4533 >    }
4534 >
4535 >    /**
4536 >     * Returns the result of accumulating the given transformation
4537 >     * of all entries using the given reducer to combine values,
4538 >     * and the given basis as an identity value.
4539 >     *
4540 >     * @param transformer a function returning the transformation
4541 >     * for an element
4542 >     * @param basis the identity (initial default value) for the reduction
4543 >     * @param reducer a commutative associative combining function
4544 >     * @return  the result of accumulating the given transformation
4545 >     * of all entries
4546 >     */
4547 >    public long reduceEntriesToLongInParallel
4548 >        (ObjectToLong<Map.Entry<K,V>> transformer,
4549 >         long basis,
4550 >         LongByLongToLong reducer) {
4551 >        return ForkJoinTasks.reduceEntriesToLong
4552 >            (this, transformer, basis, reducer).invoke();
4553 >    }
4554 >
4555 >    /**
4556 >     * Returns the result of accumulating the given transformation
4557 >     * of all entries using the given reducer to combine values,
4558 >     * and the given basis as an identity value.
4559 >     *
4560 >     * @param transformer a function returning the transformation
4561 >     * for an element
4562 >     * @param basis the identity (initial default value) for the reduction
4563 >     * @param reducer a commutative associative combining function
4564 >     * @return the result of accumulating the given transformation
4565 >     * of all entries
4566 >     */
4567 >    public int reduceEntriesToIntInParallel
4568 >        (ObjectToInt<Map.Entry<K,V>> transformer,
4569 >         int basis,
4570 >         IntByIntToInt reducer) {
4571 >        return ForkJoinTasks.reduceEntriesToInt
4572 >            (this, transformer, basis, reducer).invoke();
4573 >    }
4574 >
4575 >
4576 >    /* ----------------Views -------------- */
4577 >
4578 >    /**
4579 >     * Base class for views.
4580 >     */
4581 >    abstract static class CHMView<K,V> {
4582 >        final ConcurrentHashMapV8<K,V> map;
4583 >        CHMView(ConcurrentHashMapV8<K,V> map)  { this.map = map; }
4584 >
4585 >        /**
4586 >         * Returns the map backing this view.
4587 >         *
4588 >         * @return the map backing this view
4589 >         */
4590 >        public ConcurrentHashMapV8<K,V> getMap() { return map; }
4591 >
4592 >        public final int size()                 { return map.size(); }
4593 >        public final boolean isEmpty()          { return map.isEmpty(); }
4594 >        public final void clear()               { map.clear(); }
4595 >
4596 >        // implementations below rely on concrete classes supplying these
4597 >        public abstract Iterator<?> iterator();
4598 >        public abstract boolean contains(Object o);
4599 >        public abstract boolean remove(Object o);
4600 >
4601 >        private static final String oomeMsg = "Required array size too large";
4602 >
4603 >        public final Object[] toArray() {
4604 >            long sz = map.mappingCount();
4605 >            if (sz > (long)(MAX_ARRAY_SIZE))
4606 >                throw new OutOfMemoryError(oomeMsg);
4607 >            int n = (int)sz;
4608 >            Object[] r = new Object[n];
4609 >            int i = 0;
4610 >            Iterator<?> it = iterator();
4611 >            while (it.hasNext()) {
4612 >                if (i == n) {
4613 >                    if (n >= MAX_ARRAY_SIZE)
4614 >                        throw new OutOfMemoryError(oomeMsg);
4615 >                    if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4616 >                        n = MAX_ARRAY_SIZE;
4617 >                    else
4618 >                        n += (n >>> 1) + 1;
4619 >                    r = Arrays.copyOf(r, n);
4620 >                }
4621 >                r[i++] = it.next();
4622 >            }
4623 >            return (i == n) ? r : Arrays.copyOf(r, i);
4624 >        }
4625 >
4626 >        @SuppressWarnings("unchecked") public final <T> T[] toArray(T[] a) {
4627 >            long sz = map.mappingCount();
4628 >            if (sz > (long)(MAX_ARRAY_SIZE))
4629 >                throw new OutOfMemoryError(oomeMsg);
4630 >            int m = (int)sz;
4631 >            T[] r = (a.length >= m) ? a :
4632 >                (T[])java.lang.reflect.Array
4633 >                .newInstance(a.getClass().getComponentType(), m);
4634 >            int n = r.length;
4635 >            int i = 0;
4636 >            Iterator<?> it = iterator();
4637 >            while (it.hasNext()) {
4638 >                if (i == n) {
4639 >                    if (n >= MAX_ARRAY_SIZE)
4640 >                        throw new OutOfMemoryError(oomeMsg);
4641 >                    if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4642 >                        n = MAX_ARRAY_SIZE;
4643 >                    else
4644 >                        n += (n >>> 1) + 1;
4645 >                    r = Arrays.copyOf(r, n);
4646 >                }
4647 >                r[i++] = (T)it.next();
4648 >            }
4649 >            if (a == r && i < n) {
4650 >                r[i] = null; // null-terminate
4651 >                return r;
4652 >            }
4653 >            return (i == n) ? r : Arrays.copyOf(r, i);
4654 >        }
4655 >
4656 >        public final int hashCode() {
4657 >            int h = 0;
4658 >            for (Iterator<?> it = iterator(); it.hasNext();)
4659 >                h += it.next().hashCode();
4660 >            return h;
4661 >        }
4662 >
4663 >        public final String toString() {
4664 >            StringBuilder sb = new StringBuilder();
4665 >            sb.append('[');
4666 >            Iterator<?> it = iterator();
4667 >            if (it.hasNext()) {
4668 >                for (;;) {
4669 >                    Object e = it.next();
4670 >                    sb.append(e == this ? "(this Collection)" : e);
4671 >                    if (!it.hasNext())
4672 >                        break;
4673 >                    sb.append(',').append(' ');
4674 >                }
4675 >            }
4676 >            return sb.append(']').toString();
4677 >        }
4678 >
4679 >        public final boolean containsAll(Collection<?> c) {
4680 >            if (c != this) {
4681 >                for (Iterator<?> it = c.iterator(); it.hasNext();) {
4682 >                    Object e = it.next();
4683 >                    if (e == null || !contains(e))
4684 >                        return false;
4685 >                }
4686 >            }
4687 >            return true;
4688 >        }
4689 >
4690 >        public final boolean removeAll(Collection<?> c) {
4691 >            boolean modified = false;
4692 >            for (Iterator<?> it = iterator(); it.hasNext();) {
4693 >                if (c.contains(it.next())) {
4694 >                    it.remove();
4695 >                    modified = true;
4696 >                }
4697 >            }
4698 >            return modified;
4699 >        }
4700 >
4701 >        public final boolean retainAll(Collection<?> c) {
4702 >            boolean modified = false;
4703 >            for (Iterator<?> it = iterator(); it.hasNext();) {
4704 >                if (!c.contains(it.next())) {
4705 >                    it.remove();
4706 >                    modified = true;
4707 >                }
4708 >            }
4709 >            return modified;
4710 >        }
4711 >
4712 >    }
4713 >
4714 >    /**
4715 >     * A view of a ConcurrentHashMapV8 as a {@link Set} of keys, in
4716 >     * which additions may optionally be enabled by mapping to a
4717 >     * common value.  This class cannot be directly instantiated. See
4718 >     * {@link #keySet()}, {@link #keySet(Object)}, {@link #newKeySet()},
4719 >     * {@link #newKeySet(int)}.
4720 >     */
4721 >    public static class KeySetView<K,V> extends CHMView<K,V>
4722 >        implements Set<K>, java.io.Serializable {
4723 >        private static final long serialVersionUID = 7249069246763182397L;
4724 >        private final V value;
4725 >        KeySetView(ConcurrentHashMapV8<K,V> map, V value) {  // non-public
4726 >            super(map);
4727 >            this.value = value;
4728 >        }
4729 >
4730 >        /**
4731 >         * Returns the default mapped value for additions,
4732 >         * or {@code null} if additions are not supported.
4733 >         *
4734 >         * @return the default mapped value for additions, or {@code null}
4735 >         * if not supported
4736 >         */
4737 >        public V getMappedValue() { return value; }
4738 >
4739 >        // implement Set API
4740 >
4741 >        public boolean contains(Object o) { return map.containsKey(o); }
4742 >        public boolean remove(Object o)   { return map.remove(o) != null; }
4743 >
4744 >        /**
4745 >         * Returns a "weakly consistent" iterator that will never
4746 >         * throw {@link ConcurrentModificationException}, and
4747 >         * guarantees to traverse elements as they existed upon
4748 >         * construction of the iterator, and may (but is not
4749 >         * guaranteed to) reflect any modifications subsequent to
4750 >         * construction.
4751 >         *
4752 >         * @return an iterator over the keys of this map
4753 >         */
4754 >        public Iterator<K> iterator()     { return new KeyIterator<K,V>(map); }
4755 >        public boolean add(K e) {
4756 >            V v;
4757 >            if ((v = value) == null)
4758 >                throw new UnsupportedOperationException();
4759 >            return map.internalPut(e, v, true) == null;
4760 >        }
4761 >        public boolean addAll(Collection<? extends K> c) {
4762 >            boolean added = false;
4763 >            V v;
4764 >            if ((v = value) == null)
4765 >                throw new UnsupportedOperationException();
4766 >            for (K e : c) {
4767 >                if (map.internalPut(e, v, true) == null)
4768 >                    added = true;
4769 >            }
4770 >            return added;
4771 >        }
4772 >        public boolean equals(Object o) {
4773 >            Set<?> c;
4774 >            return ((o instanceof Set) &&
4775 >                    ((c = (Set<?>)o) == this ||
4776 >                     (containsAll(c) && c.containsAll(this))));
4777 >        }
4778 >    }
4779 >
4780 >    /**
4781 >     * A view of a ConcurrentHashMapV8 as a {@link Collection} of
4782 >     * values, in which additions are disabled. This class cannot be
4783 >     * directly instantiated. See {@link #values()}.
4784 >     *
4785 >     * <p>The view's {@code iterator} is a "weakly consistent" iterator
4786 >     * that will never throw {@link ConcurrentModificationException},
4787 >     * and guarantees to traverse elements as they existed upon
4788 >     * construction of the iterator, and may (but is not guaranteed to)
4789 >     * reflect any modifications subsequent to construction.
4790 >     */
4791 >    public static final class ValuesView<K,V> extends CHMView<K,V>
4792 >        implements Collection<V> {
4793 >        ValuesView(ConcurrentHashMapV8<K,V> map)   { super(map); }
4794 >        public final boolean contains(Object o) { return map.containsValue(o); }
4795 >        public final boolean remove(Object o) {
4796 >            if (o != null) {
4797 >                Iterator<V> it = new ValueIterator<K,V>(map);
4798 >                while (it.hasNext()) {
4799 >                    if (o.equals(it.next())) {
4800 >                        it.remove();
4801 >                        return true;
4802 >                    }
4803 >                }
4804 >            }
4805 >            return false;
4806 >        }
4807 >
4808 >        /**
4809 >         * Returns a "weakly consistent" iterator that will never
4810 >         * throw {@link ConcurrentModificationException}, and
4811 >         * guarantees to traverse elements as they existed upon
4812 >         * construction of the iterator, and may (but is not
4813 >         * guaranteed to) reflect any modifications subsequent to
4814 >         * construction.
4815 >         *
4816 >         * @return an iterator over the values of this map
4817 >         */
4818 >        public final Iterator<V> iterator() {
4819 >            return new ValueIterator<K,V>(map);
4820 >        }
4821 >        public final boolean add(V e) {
4822 >            throw new UnsupportedOperationException();
4823 >        }
4824 >        public final boolean addAll(Collection<? extends V> c) {
4825 >            throw new UnsupportedOperationException();
4826 >        }
4827 >
4828 >    }
4829 >
4830 >    /**
4831 >     * A view of a ConcurrentHashMapV8 as a {@link Set} of (key, value)
4832 >     * entries.  This class cannot be directly instantiated. See
4833 >     * {@link #entrySet()}.
4834 >     */
4835 >    public static final class EntrySetView<K,V> extends CHMView<K,V>
4836 >        implements Set<Map.Entry<K,V>> {
4837 >        EntrySetView(ConcurrentHashMapV8<K,V> map) { super(map); }
4838 >        public final boolean contains(Object o) {
4839 >            Object k, v, r; Map.Entry<?,?> e;
4840 >            return ((o instanceof Map.Entry) &&
4841 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4842 >                    (r = map.get(k)) != null &&
4843 >                    (v = e.getValue()) != null &&
4844 >                    (v == r || v.equals(r)));
4845 >        }
4846 >        public final boolean remove(Object o) {
4847 >            Object k, v; Map.Entry<?,?> e;
4848 >            return ((o instanceof Map.Entry) &&
4849 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4850 >                    (v = e.getValue()) != null &&
4851 >                    map.remove(k, v));
4852 >        }
4853 >
4854 >        /**
4855 >         * Returns a "weakly consistent" iterator that will never
4856 >         * throw {@link ConcurrentModificationException}, and
4857 >         * guarantees to traverse elements as they existed upon
4858 >         * construction of the iterator, and may (but is not
4859 >         * guaranteed to) reflect any modifications subsequent to
4860 >         * construction.
4861 >         *
4862 >         * @return an iterator over the entries of this map
4863 >         */
4864 >        public final Iterator<Map.Entry<K,V>> iterator() {
4865 >            return new EntryIterator<K,V>(map);
4866 >        }
4867 >
4868 >        public final boolean add(Entry<K,V> e) {
4869 >            return map.internalPut(e.getKey(), e.getValue(), false) == null;
4870 >        }
4871 >        public final boolean addAll(Collection<? extends Entry<K,V>> c) {
4872 >            boolean added = false;
4873 >            for (Entry<K,V> e : c) {
4874 >                if (add(e))
4875 >                    added = true;
4876 >            }
4877 >            return added;
4878 >        }
4879 >        public boolean equals(Object o) {
4880 >            Set<?> c;
4881 >            return ((o instanceof Set) &&
4882 >                    ((c = (Set<?>)o) == this ||
4883 >                     (containsAll(c) && c.containsAll(this))));
4884 >        }
4885 >    }
4886 >
4887 >    // ---------------------------------------------------------------------
4888 >
4889 >    /**
4890 >     * Predefined tasks for performing bulk parallel operations on
4891 >     * ConcurrentHashMapV8s. These tasks follow the forms and rules used
4892 >     * for bulk operations. Each method has the same name, but returns
4893 >     * a task rather than invoking it. These methods may be useful in
4894 >     * custom applications such as submitting a task without waiting
4895 >     * for completion, using a custom pool, or combining with other
4896 >     * tasks.
4897 >     */
4898 >    public static class ForkJoinTasks {
4899 >        private ForkJoinTasks() {}
4900 >
4901 >        /**
4902 >         * Returns a task that when invoked, performs the given
4903 >         * action for each (key, value)
4904 >         *
4905 >         * @param map the map
4906 >         * @param action the action
4907 >         * @return the task
4908 >         */
4909 >        public static <K,V> ForkJoinTask<Void> forEach
4910 >            (ConcurrentHashMapV8<K,V> map,
4911 >             BiAction<K,V> action) {
4912 >            if (action == null) throw new NullPointerException();
4913 >            return new ForEachMappingTask<K,V>(map, null, -1, action);
4914 >        }
4915 >
4916 >        /**
4917 >         * Returns a task that when invoked, performs the given
4918 >         * action for each non-null transformation of each (key, value)
4919 >         *
4920 >         * @param map the map
4921 >         * @param transformer a function returning the transformation
4922 >         * for an element, or null if there is no transformation (in
4923 >         * which case the action is not applied)
4924 >         * @param action the action
4925 >         * @return the task
4926 >         */
4927 >        public static <K,V,U> ForkJoinTask<Void> forEach
4928 >            (ConcurrentHashMapV8<K,V> map,
4929 >             BiFun<? super K, ? super V, ? extends U> transformer,
4930 >             Action<U> action) {
4931 >            if (transformer == null || action == null)
4932 >                throw new NullPointerException();
4933 >            return new ForEachTransformedMappingTask<K,V,U>
4934 >                (map, null, -1, transformer, action);
4935 >        }
4936 >
4937 >        /**
4938 >         * Returns a task that when invoked, returns a non-null result
4939 >         * from applying the given search function on each (key,
4940 >         * value), or null if none. Upon success, further element
4941 >         * processing is suppressed and the results of any other
4942 >         * parallel invocations of the search function are ignored.
4943 >         *
4944 >         * @param map the map
4945 >         * @param searchFunction a function returning a non-null
4946 >         * result on success, else null
4947 >         * @return the task
4948 >         */
4949 >        public static <K,V,U> ForkJoinTask<U> search
4950 >            (ConcurrentHashMapV8<K,V> map,
4951 >             BiFun<? super K, ? super V, ? extends U> searchFunction) {
4952 >            if (searchFunction == null) throw new NullPointerException();
4953 >            return new SearchMappingsTask<K,V,U>
4954 >                (map, null, -1, searchFunction,
4955 >                 new AtomicReference<U>());
4956 >        }
4957 >
4958 >        /**
4959 >         * Returns a task that when invoked, returns the result of
4960 >         * accumulating the given transformation of all (key, value) pairs
4961 >         * using the given reducer to combine values, or null if none.
4962 >         *
4963 >         * @param map the map
4964 >         * @param transformer a function returning the transformation
4965 >         * for an element, or null if there is no transformation (in
4966 >         * which case it is not combined)
4967 >         * @param reducer a commutative associative combining function
4968 >         * @return the task
4969 >         */
4970 >        public static <K,V,U> ForkJoinTask<U> reduce
4971 >            (ConcurrentHashMapV8<K,V> map,
4972 >             BiFun<? super K, ? super V, ? extends U> transformer,
4973 >             BiFun<? super U, ? super U, ? extends U> reducer) {
4974 >            if (transformer == null || reducer == null)
4975 >                throw new NullPointerException();
4976 >            return new MapReduceMappingsTask<K,V,U>
4977 >                (map, null, -1, null, transformer, reducer);
4978 >        }
4979 >
4980 >        /**
4981 >         * Returns a task that when invoked, returns the result of
4982 >         * accumulating the given transformation of all (key, value) pairs
4983 >         * using the given reducer to combine values, and the given
4984 >         * basis as an identity value.
4985 >         *
4986 >         * @param map the map
4987 >         * @param transformer a function returning the transformation
4988 >         * for an element
4989 >         * @param basis the identity (initial default value) for the reduction
4990 >         * @param reducer a commutative associative combining function
4991 >         * @return the task
4992 >         */
4993 >        public static <K,V> ForkJoinTask<Double> reduceToDouble
4994 >            (ConcurrentHashMapV8<K,V> map,
4995 >             ObjectByObjectToDouble<? super K, ? super V> transformer,
4996 >             double basis,
4997 >             DoubleByDoubleToDouble reducer) {
4998 >            if (transformer == null || reducer == null)
4999 >                throw new NullPointerException();
5000 >            return new MapReduceMappingsToDoubleTask<K,V>
5001 >                (map, null, -1, null, transformer, basis, reducer);
5002 >        }
5003 >
5004 >        /**
5005 >         * Returns a task that when invoked, returns the result of
5006 >         * accumulating the given transformation of all (key, value) pairs
5007 >         * using the given reducer to combine values, and the given
5008 >         * basis as an identity value.
5009 >         *
5010 >         * @param map the map
5011 >         * @param transformer a function returning the transformation
5012 >         * for an element
5013 >         * @param basis the identity (initial default value) for the reduction
5014 >         * @param reducer a commutative associative combining function
5015 >         * @return the task
5016 >         */
5017 >        public static <K,V> ForkJoinTask<Long> reduceToLong
5018 >            (ConcurrentHashMapV8<K,V> map,
5019 >             ObjectByObjectToLong<? super K, ? super V> transformer,
5020 >             long basis,
5021 >             LongByLongToLong reducer) {
5022 >            if (transformer == null || reducer == null)
5023 >                throw new NullPointerException();
5024 >            return new MapReduceMappingsToLongTask<K,V>
5025 >                (map, null, -1, null, transformer, basis, reducer);
5026 >        }
5027 >
5028 >        /**
5029 >         * Returns a task that when invoked, returns the result of
5030 >         * accumulating the given transformation of all (key, value) pairs
5031 >         * using the given reducer to combine values, and the given
5032 >         * basis as an identity value.
5033 >         *
5034 >         * @param transformer a function returning the transformation
5035 >         * for an element
5036 >         * @param basis the identity (initial default value) for the reduction
5037 >         * @param reducer a commutative associative combining function
5038 >         * @return the task
5039 >         */
5040 >        public static <K,V> ForkJoinTask<Integer> reduceToInt
5041 >            (ConcurrentHashMapV8<K,V> map,
5042 >             ObjectByObjectToInt<? super K, ? super V> transformer,
5043 >             int basis,
5044 >             IntByIntToInt reducer) {
5045 >            if (transformer == null || reducer == null)
5046 >                throw new NullPointerException();
5047 >            return new MapReduceMappingsToIntTask<K,V>
5048 >                (map, null, -1, null, transformer, basis, reducer);
5049 >        }
5050 >
5051 >        /**
5052 >         * Returns a task that when invoked, performs the given action
5053 >         * for each key.
5054 >         *
5055 >         * @param map the map
5056 >         * @param action the action
5057 >         * @return the task
5058 >         */
5059 >        public static <K,V> ForkJoinTask<Void> forEachKey
5060 >            (ConcurrentHashMapV8<K,V> map,
5061 >             Action<K> action) {
5062 >            if (action == null) throw new NullPointerException();
5063 >            return new ForEachKeyTask<K,V>(map, null, -1, action);
5064 >        }
5065 >
5066 >        /**
5067 >         * Returns a task that when invoked, performs the given action
5068 >         * for each non-null transformation of each key.
5069 >         *
5070 >         * @param map the map
5071 >         * @param transformer a function returning the transformation
5072 >         * for an element, or null if there is no transformation (in
5073 >         * which case the action is not applied)
5074 >         * @param action the action
5075 >         * @return the task
5076 >         */
5077 >        public static <K,V,U> ForkJoinTask<Void> forEachKey
5078 >            (ConcurrentHashMapV8<K,V> map,
5079 >             Fun<? super K, ? extends U> transformer,
5080 >             Action<U> action) {
5081 >            if (transformer == null || action == null)
5082 >                throw new NullPointerException();
5083 >            return new ForEachTransformedKeyTask<K,V,U>
5084 >                (map, null, -1, transformer, action);
5085 >        }
5086 >
5087 >        /**
5088 >         * Returns a task that when invoked, returns a non-null result
5089 >         * from applying the given search function on each key, or
5090 >         * null if none.  Upon success, further element processing is
5091 >         * suppressed and the results of any other parallel
5092 >         * invocations of the search function are ignored.
5093 >         *
5094 >         * @param map the map
5095 >         * @param searchFunction a function returning a non-null
5096 >         * result on success, else null
5097 >         * @return the task
5098 >         */
5099 >        public static <K,V,U> ForkJoinTask<U> searchKeys
5100 >            (ConcurrentHashMapV8<K,V> map,
5101 >             Fun<? super K, ? extends U> searchFunction) {
5102 >            if (searchFunction == null) throw new NullPointerException();
5103 >            return new SearchKeysTask<K,V,U>
5104 >                (map, null, -1, searchFunction,
5105 >                 new AtomicReference<U>());
5106 >        }
5107 >
5108 >        /**
5109 >         * Returns a task that when invoked, returns the result of
5110 >         * accumulating all keys using the given reducer to combine
5111 >         * values, or null if none.
5112 >         *
5113 >         * @param map the map
5114 >         * @param reducer a commutative associative combining function
5115 >         * @return the task
5116 >         */
5117 >        public static <K,V> ForkJoinTask<K> reduceKeys
5118 >            (ConcurrentHashMapV8<K,V> map,
5119 >             BiFun<? super K, ? super K, ? extends K> reducer) {
5120 >            if (reducer == null) throw new NullPointerException();
5121 >            return new ReduceKeysTask<K,V>
5122 >                (map, null, -1, null, reducer);
5123 >        }
5124 >
5125 >        /**
5126 >         * Returns a task that when invoked, returns the result of
5127 >         * accumulating the given transformation of all keys using the given
5128 >         * reducer to combine values, or null if none.
5129 >         *
5130 >         * @param map the map
5131 >         * @param transformer a function returning the transformation
5132 >         * for an element, or null if there is no transformation (in
5133 >         * which case it is not combined)
5134 >         * @param reducer a commutative associative combining function
5135 >         * @return the task
5136 >         */
5137 >        public static <K,V,U> ForkJoinTask<U> reduceKeys
5138 >            (ConcurrentHashMapV8<K,V> map,
5139 >             Fun<? super K, ? extends U> transformer,
5140 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5141 >            if (transformer == null || reducer == null)
5142 >                throw new NullPointerException();
5143 >            return new MapReduceKeysTask<K,V,U>
5144 >                (map, null, -1, null, transformer, reducer);
5145 >        }
5146 >
5147 >        /**
5148 >         * Returns a task that when invoked, returns the result of
5149 >         * accumulating the given transformation of all keys using the given
5150 >         * reducer to combine values, and the given basis as an
5151 >         * identity value.
5152 >         *
5153 >         * @param map the map
5154 >         * @param transformer a function returning the transformation
5155 >         * for an element
5156 >         * @param basis the identity (initial default value) for the reduction
5157 >         * @param reducer a commutative associative combining function
5158 >         * @return the task
5159 >         */
5160 >        public static <K,V> ForkJoinTask<Double> reduceKeysToDouble
5161 >            (ConcurrentHashMapV8<K,V> map,
5162 >             ObjectToDouble<? super K> transformer,
5163 >             double basis,
5164 >             DoubleByDoubleToDouble reducer) {
5165 >            if (transformer == null || reducer == null)
5166 >                throw new NullPointerException();
5167 >            return new MapReduceKeysToDoubleTask<K,V>
5168 >                (map, null, -1, null, transformer, basis, reducer);
5169 >        }
5170 >
5171 >        /**
5172 >         * Returns a task that when invoked, returns the result of
5173 >         * accumulating the given transformation of all keys using the given
5174 >         * reducer to combine values, and the given basis as an
5175 >         * identity value.
5176 >         *
5177 >         * @param map the map
5178 >         * @param transformer a function returning the transformation
5179 >         * for an element
5180 >         * @param basis the identity (initial default value) for the reduction
5181 >         * @param reducer a commutative associative combining function
5182 >         * @return the task
5183 >         */
5184 >        public static <K,V> ForkJoinTask<Long> reduceKeysToLong
5185 >            (ConcurrentHashMapV8<K,V> map,
5186 >             ObjectToLong<? super K> transformer,
5187 >             long basis,
5188 >             LongByLongToLong reducer) {
5189 >            if (transformer == null || reducer == null)
5190 >                throw new NullPointerException();
5191 >            return new MapReduceKeysToLongTask<K,V>
5192 >                (map, null, -1, null, transformer, basis, reducer);
5193 >        }
5194 >
5195 >        /**
5196 >         * Returns a task that when invoked, returns the result of
5197 >         * accumulating the given transformation of all keys using the given
5198 >         * reducer to combine values, and the given basis as an
5199 >         * identity value.
5200 >         *
5201 >         * @param map the map
5202 >         * @param transformer a function returning the transformation
5203 >         * for an element
5204 >         * @param basis the identity (initial default value) for the reduction
5205 >         * @param reducer a commutative associative combining function
5206 >         * @return the task
5207 >         */
5208 >        public static <K,V> ForkJoinTask<Integer> reduceKeysToInt
5209 >            (ConcurrentHashMapV8<K,V> map,
5210 >             ObjectToInt<? super K> transformer,
5211 >             int basis,
5212 >             IntByIntToInt reducer) {
5213 >            if (transformer == null || reducer == null)
5214 >                throw new NullPointerException();
5215 >            return new MapReduceKeysToIntTask<K,V>
5216 >                (map, null, -1, null, transformer, basis, reducer);
5217 >        }
5218 >
5219 >        /**
5220 >         * Returns a task that when invoked, performs the given action
5221 >         * for each value.
5222 >         *
5223 >         * @param map the map
5224 >         * @param action the action
5225 >         */
5226 >        public static <K,V> ForkJoinTask<Void> forEachValue
5227 >            (ConcurrentHashMapV8<K,V> map,
5228 >             Action<V> action) {
5229 >            if (action == null) throw new NullPointerException();
5230 >            return new ForEachValueTask<K,V>(map, null, -1, action);
5231 >        }
5232 >
5233 >        /**
5234 >         * Returns a task that when invoked, performs the given action
5235 >         * for each non-null transformation of each value.
5236 >         *
5237 >         * @param map the map
5238 >         * @param transformer a function returning the transformation
5239 >         * for an element, or null if there is no transformation (in
5240 >         * which case the action is not applied)
5241 >         * @param action the action
5242 >         */
5243 >        public static <K,V,U> ForkJoinTask<Void> forEachValue
5244 >            (ConcurrentHashMapV8<K,V> map,
5245 >             Fun<? super V, ? extends U> transformer,
5246 >             Action<U> action) {
5247 >            if (transformer == null || action == null)
5248 >                throw new NullPointerException();
5249 >            return new ForEachTransformedValueTask<K,V,U>
5250 >                (map, null, -1, transformer, action);
5251 >        }
5252 >
5253 >        /**
5254 >         * Returns a task that when invoked, returns a non-null result
5255 >         * from applying the given search function on each value, or
5256 >         * null if none.  Upon success, further element processing is
5257 >         * suppressed and the results of any other parallel
5258 >         * invocations of the search function are ignored.
5259 >         *
5260 >         * @param map the map
5261 >         * @param searchFunction a function returning a non-null
5262 >         * result on success, else null
5263 >         * @return the task
5264 >         */
5265 >        public static <K,V,U> ForkJoinTask<U> searchValues
5266 >            (ConcurrentHashMapV8<K,V> map,
5267 >             Fun<? super V, ? extends U> searchFunction) {
5268 >            if (searchFunction == null) throw new NullPointerException();
5269 >            return new SearchValuesTask<K,V,U>
5270 >                (map, null, -1, searchFunction,
5271 >                 new AtomicReference<U>());
5272 >        }
5273 >
5274 >        /**
5275 >         * Returns a task that when invoked, returns the result of
5276 >         * accumulating all values using the given reducer to combine
5277 >         * values, or null if none.
5278 >         *
5279 >         * @param map the map
5280 >         * @param reducer a commutative associative combining function
5281 >         * @return the task
5282 >         */
5283 >        public static <K,V> ForkJoinTask<V> reduceValues
5284 >            (ConcurrentHashMapV8<K,V> map,
5285 >             BiFun<? super V, ? super V, ? extends V> reducer) {
5286 >            if (reducer == null) throw new NullPointerException();
5287 >            return new ReduceValuesTask<K,V>
5288 >                (map, null, -1, null, reducer);
5289 >        }
5290 >
5291 >        /**
5292 >         * Returns a task that when invoked, returns the result of
5293 >         * accumulating the given transformation of all values using the
5294 >         * given reducer to combine values, or null if none.
5295 >         *
5296 >         * @param map the map
5297 >         * @param transformer a function returning the transformation
5298 >         * for an element, or null if there is no transformation (in
5299 >         * which case it is not combined)
5300 >         * @param reducer a commutative associative combining function
5301 >         * @return the task
5302 >         */
5303 >        public static <K,V,U> ForkJoinTask<U> reduceValues
5304 >            (ConcurrentHashMapV8<K,V> map,
5305 >             Fun<? super V, ? extends U> transformer,
5306 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5307 >            if (transformer == null || reducer == null)
5308 >                throw new NullPointerException();
5309 >            return new MapReduceValuesTask<K,V,U>
5310 >                (map, null, -1, null, transformer, reducer);
5311 >        }
5312 >
5313 >        /**
5314 >         * Returns a task that when invoked, returns the result of
5315 >         * accumulating the given transformation of all values using the
5316 >         * given reducer to combine values, and the given basis as an
5317 >         * identity value.
5318 >         *
5319 >         * @param map the map
5320 >         * @param transformer a function returning the transformation
5321 >         * for an element
5322 >         * @param basis the identity (initial default value) for the reduction
5323 >         * @param reducer a commutative associative combining function
5324 >         * @return the task
5325 >         */
5326 >        public static <K,V> ForkJoinTask<Double> reduceValuesToDouble
5327 >            (ConcurrentHashMapV8<K,V> map,
5328 >             ObjectToDouble<? super V> transformer,
5329 >             double basis,
5330 >             DoubleByDoubleToDouble reducer) {
5331 >            if (transformer == null || reducer == null)
5332 >                throw new NullPointerException();
5333 >            return new MapReduceValuesToDoubleTask<K,V>
5334 >                (map, null, -1, null, transformer, basis, reducer);
5335 >        }
5336 >
5337 >        /**
5338 >         * Returns a task that when invoked, returns the result of
5339 >         * accumulating the given transformation of all values using the
5340 >         * given reducer to combine values, and the given basis as an
5341 >         * identity value.
5342 >         *
5343 >         * @param map the map
5344 >         * @param transformer a function returning the transformation
5345 >         * for an element
5346 >         * @param basis the identity (initial default value) for the reduction
5347 >         * @param reducer a commutative associative combining function
5348 >         * @return the task
5349 >         */
5350 >        public static <K,V> ForkJoinTask<Long> reduceValuesToLong
5351 >            (ConcurrentHashMapV8<K,V> map,
5352 >             ObjectToLong<? super V> transformer,
5353 >             long basis,
5354 >             LongByLongToLong reducer) {
5355 >            if (transformer == null || reducer == null)
5356 >                throw new NullPointerException();
5357 >            return new MapReduceValuesToLongTask<K,V>
5358 >                (map, null, -1, null, transformer, basis, reducer);
5359 >        }
5360 >
5361 >        /**
5362 >         * Returns a task that when invoked, returns the result of
5363 >         * accumulating the given transformation of all values using the
5364 >         * given reducer to combine values, and the given basis as an
5365 >         * identity value.
5366 >         *
5367 >         * @param map the map
5368 >         * @param transformer a function returning the transformation
5369 >         * for an element
5370 >         * @param basis the identity (initial default value) for the reduction
5371 >         * @param reducer a commutative associative combining function
5372 >         * @return the task
5373 >         */
5374 >        public static <K,V> ForkJoinTask<Integer> reduceValuesToInt
5375 >            (ConcurrentHashMapV8<K,V> map,
5376 >             ObjectToInt<? super V> transformer,
5377 >             int basis,
5378 >             IntByIntToInt reducer) {
5379 >            if (transformer == null || reducer == null)
5380 >                throw new NullPointerException();
5381 >            return new MapReduceValuesToIntTask<K,V>
5382 >                (map, null, -1, null, transformer, basis, reducer);
5383 >        }
5384 >
5385 >        /**
5386 >         * Returns a task that when invoked, perform the given action
5387 >         * for each entry.
5388 >         *
5389 >         * @param map the map
5390 >         * @param action the action
5391 >         */
5392 >        public static <K,V> ForkJoinTask<Void> forEachEntry
5393 >            (ConcurrentHashMapV8<K,V> map,
5394 >             Action<Map.Entry<K,V>> action) {
5395 >            if (action == null) throw new NullPointerException();
5396 >            return new ForEachEntryTask<K,V>(map, null, -1, action);
5397 >        }
5398 >
5399 >        /**
5400 >         * Returns a task that when invoked, perform the given action
5401 >         * for each non-null transformation of each entry.
5402 >         *
5403 >         * @param map the map
5404 >         * @param transformer a function returning the transformation
5405 >         * for an element, or null if there is no transformation (in
5406 >         * which case the action is not applied)
5407 >         * @param action the action
5408 >         */
5409 >        public static <K,V,U> ForkJoinTask<Void> forEachEntry
5410 >            (ConcurrentHashMapV8<K,V> map,
5411 >             Fun<Map.Entry<K,V>, ? extends U> transformer,
5412 >             Action<U> action) {
5413 >            if (transformer == null || action == null)
5414 >                throw new NullPointerException();
5415 >            return new ForEachTransformedEntryTask<K,V,U>
5416 >                (map, null, -1, transformer, action);
5417 >        }
5418 >
5419 >        /**
5420 >         * Returns a task that when invoked, returns a non-null result
5421 >         * from applying the given search function on each entry, or
5422 >         * null if none.  Upon success, further element processing is
5423 >         * suppressed and the results of any other parallel
5424 >         * invocations of the search function are ignored.
5425 >         *
5426 >         * @param map the map
5427 >         * @param searchFunction a function returning a non-null
5428 >         * result on success, else null
5429 >         * @return the task
5430 >         */
5431 >        public static <K,V,U> ForkJoinTask<U> searchEntries
5432 >            (ConcurrentHashMapV8<K,V> map,
5433 >             Fun<Map.Entry<K,V>, ? extends U> searchFunction) {
5434 >            if (searchFunction == null) throw new NullPointerException();
5435 >            return new SearchEntriesTask<K,V,U>
5436 >                (map, null, -1, searchFunction,
5437 >                 new AtomicReference<U>());
5438 >        }
5439 >
5440 >        /**
5441 >         * Returns a task that when invoked, returns the result of
5442 >         * accumulating all entries using the given reducer to combine
5443 >         * values, or null if none.
5444 >         *
5445 >         * @param map the map
5446 >         * @param reducer a commutative associative combining function
5447 >         * @return the task
5448 >         */
5449 >        public static <K,V> ForkJoinTask<Map.Entry<K,V>> reduceEntries
5450 >            (ConcurrentHashMapV8<K,V> map,
5451 >             BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5452 >            if (reducer == null) throw new NullPointerException();
5453 >            return new ReduceEntriesTask<K,V>
5454 >                (map, null, -1, null, reducer);
5455 >        }
5456 >
5457 >        /**
5458 >         * Returns a task that when invoked, returns the result of
5459 >         * accumulating the given transformation of all entries using the
5460 >         * given reducer to combine values, or null if none.
5461 >         *
5462 >         * @param map the map
5463 >         * @param transformer a function returning the transformation
5464 >         * for an element, or null if there is no transformation (in
5465 >         * which case it is not combined)
5466 >         * @param reducer a commutative associative combining function
5467 >         * @return the task
5468 >         */
5469 >        public static <K,V,U> ForkJoinTask<U> reduceEntries
5470 >            (ConcurrentHashMapV8<K,V> map,
5471 >             Fun<Map.Entry<K,V>, ? extends U> transformer,
5472 >             BiFun<? super U, ? super U, ? extends U> reducer) {
5473 >            if (transformer == null || reducer == null)
5474 >                throw new NullPointerException();
5475 >            return new MapReduceEntriesTask<K,V,U>
5476 >                (map, null, -1, null, transformer, reducer);
5477 >        }
5478 >
5479 >        /**
5480 >         * Returns a task that when invoked, returns the result of
5481 >         * accumulating the given transformation of all entries using the
5482 >         * given reducer to combine values, and the given basis as an
5483 >         * identity value.
5484 >         *
5485 >         * @param map the map
5486 >         * @param transformer a function returning the transformation
5487 >         * for an element
5488 >         * @param basis the identity (initial default value) for the reduction
5489 >         * @param reducer a commutative associative combining function
5490 >         * @return the task
5491 >         */
5492 >        public static <K,V> ForkJoinTask<Double> reduceEntriesToDouble
5493 >            (ConcurrentHashMapV8<K,V> map,
5494 >             ObjectToDouble<Map.Entry<K,V>> transformer,
5495 >             double basis,
5496 >             DoubleByDoubleToDouble reducer) {
5497 >            if (transformer == null || reducer == null)
5498 >                throw new NullPointerException();
5499 >            return new MapReduceEntriesToDoubleTask<K,V>
5500 >                (map, null, -1, null, transformer, basis, reducer);
5501 >        }
5502 >
5503 >        /**
5504 >         * Returns a task that when invoked, returns the result of
5505 >         * accumulating the given transformation of all entries using the
5506 >         * given reducer to combine values, and the given basis as an
5507 >         * identity value.
5508 >         *
5509 >         * @param map the map
5510 >         * @param transformer a function returning the transformation
5511 >         * for an element
5512 >         * @param basis the identity (initial default value) for the reduction
5513 >         * @param reducer a commutative associative combining function
5514 >         * @return the task
5515 >         */
5516 >        public static <K,V> ForkJoinTask<Long> reduceEntriesToLong
5517 >            (ConcurrentHashMapV8<K,V> map,
5518 >             ObjectToLong<Map.Entry<K,V>> transformer,
5519 >             long basis,
5520 >             LongByLongToLong reducer) {
5521 >            if (transformer == null || reducer == null)
5522 >                throw new NullPointerException();
5523 >            return new MapReduceEntriesToLongTask<K,V>
5524 >                (map, null, -1, null, transformer, basis, reducer);
5525 >        }
5526 >
5527 >        /**
5528 >         * Returns a task that when invoked, returns the result of
5529 >         * accumulating the given transformation of all entries using the
5530 >         * given reducer to combine values, and the given basis as an
5531 >         * identity value.
5532 >         *
5533 >         * @param map the map
5534 >         * @param transformer a function returning the transformation
5535 >         * for an element
5536 >         * @param basis the identity (initial default value) for the reduction
5537 >         * @param reducer a commutative associative combining function
5538 >         * @return the task
5539 >         */
5540 >        public static <K,V> ForkJoinTask<Integer> reduceEntriesToInt
5541 >            (ConcurrentHashMapV8<K,V> map,
5542 >             ObjectToInt<Map.Entry<K,V>> transformer,
5543 >             int basis,
5544 >             IntByIntToInt reducer) {
5545 >            if (transformer == null || reducer == null)
5546 >                throw new NullPointerException();
5547 >            return new MapReduceEntriesToIntTask<K,V>
5548 >                (map, null, -1, null, transformer, basis, reducer);
5549 >        }
5550 >    }
5551 >
5552 >    // -------------------------------------------------------
5553 >
5554 >    /*
5555 >     * Task classes. Coded in a regular but ugly format/style to
5556 >     * simplify checks that each variant differs in the right way from
5557 >     * others. The null screenings exist because compilers cannot tell
5558 >     * that we've already null-checked task arguments, so we force
5559 >     * simplest hoisted bypass to help avoid convoluted traps.
5560 >     */
5561 >
5562 >    @SuppressWarnings("serial") static final class ForEachKeyTask<K,V>
5563 >        extends Traverser<K,V,Void> {
5564 >        final Action<K> action;
5565 >        ForEachKeyTask
5566 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5567 >             Action<K> action) {
5568 >            super(m, p, b);
5569 >            this.action = action;
5570 >        }
5571 >        @SuppressWarnings("unchecked") public final void compute() {
5572 >            final Action<K> action;
5573 >            if ((action = this.action) != null) {
5574 >                for (int b; (b = preSplit()) > 0;)
5575 >                    new ForEachKeyTask<K,V>(map, this, b, action).fork();
5576 >                while (advance() != null)
5577 >                    action.apply((K)nextKey);
5578 >                propagateCompletion();
5579 >            }
5580 >        }
5581 >    }
5582 >
5583 >    @SuppressWarnings("serial") static final class ForEachValueTask<K,V>
5584 >        extends Traverser<K,V,Void> {
5585 >        final Action<V> action;
5586 >        ForEachValueTask
5587 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5588 >             Action<V> action) {
5589 >            super(m, p, b);
5590 >            this.action = action;
5591 >        }
5592 >        @SuppressWarnings("unchecked") public final void compute() {
5593 >            final Action<V> action;
5594 >            if ((action = this.action) != null) {
5595 >                for (int b; (b = preSplit()) > 0;)
5596 >                    new ForEachValueTask<K,V>(map, this, b, action).fork();
5597 >                V v;
5598 >                while ((v = advance()) != null)
5599 >                    action.apply(v);
5600 >                propagateCompletion();
5601 >            }
5602 >        }
5603 >    }
5604 >
5605 >    @SuppressWarnings("serial") static final class ForEachEntryTask<K,V>
5606 >        extends Traverser<K,V,Void> {
5607 >        final Action<Entry<K,V>> action;
5608 >        ForEachEntryTask
5609 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5610 >             Action<Entry<K,V>> action) {
5611 >            super(m, p, b);
5612 >            this.action = action;
5613 >        }
5614 >        @SuppressWarnings("unchecked") public final void compute() {
5615 >            final Action<Entry<K,V>> action;
5616 >            if ((action = this.action) != null) {
5617 >                for (int b; (b = preSplit()) > 0;)
5618 >                    new ForEachEntryTask<K,V>(map, this, b, action).fork();
5619 >                V v;
5620 >                while ((v = advance()) != null)
5621 >                    action.apply(entryFor((K)nextKey, v));
5622 >                propagateCompletion();
5623 >            }
5624 >        }
5625 >    }
5626 >
5627 >    @SuppressWarnings("serial") static final class ForEachMappingTask<K,V>
5628 >        extends Traverser<K,V,Void> {
5629 >        final BiAction<K,V> action;
5630 >        ForEachMappingTask
5631 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5632 >             BiAction<K,V> action) {
5633 >            super(m, p, b);
5634 >            this.action = action;
5635 >        }
5636 >        @SuppressWarnings("unchecked") public final void compute() {
5637 >            final BiAction<K,V> action;
5638 >            if ((action = this.action) != null) {
5639 >                for (int b; (b = preSplit()) > 0;)
5640 >                    new ForEachMappingTask<K,V>(map, this, b, action).fork();
5641 >                V v;
5642 >                while ((v = advance()) != null)
5643 >                    action.apply((K)nextKey, v);
5644 >                propagateCompletion();
5645 >            }
5646 >        }
5647 >    }
5648 >
5649 >    @SuppressWarnings("serial") static final class ForEachTransformedKeyTask<K,V,U>
5650 >        extends Traverser<K,V,Void> {
5651 >        final Fun<? super K, ? extends U> transformer;
5652 >        final Action<U> action;
5653 >        ForEachTransformedKeyTask
5654 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5655 >             Fun<? super K, ? extends U> transformer, Action<U> action) {
5656 >            super(m, p, b);
5657 >            this.transformer = transformer; this.action = action;
5658 >        }
5659 >        @SuppressWarnings("unchecked") public final void compute() {
5660 >            final Fun<? super K, ? extends U> transformer;
5661 >            final Action<U> action;
5662 >            if ((transformer = this.transformer) != null &&
5663 >                (action = this.action) != null) {
5664 >                for (int b; (b = preSplit()) > 0;)
5665 >                    new ForEachTransformedKeyTask<K,V,U>
5666 >                        (map, this, b, transformer, action).fork();
5667 >                U u;
5668 >                while (advance() != null) {
5669 >                    if ((u = transformer.apply((K)nextKey)) != null)
5670 >                        action.apply(u);
5671 >                }
5672 >                propagateCompletion();
5673 >            }
5674 >        }
5675 >    }
5676 >
5677 >    @SuppressWarnings("serial") static final class ForEachTransformedValueTask<K,V,U>
5678 >        extends Traverser<K,V,Void> {
5679 >        final Fun<? super V, ? extends U> transformer;
5680 >        final Action<U> action;
5681 >        ForEachTransformedValueTask
5682 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5683 >             Fun<? super V, ? extends U> transformer, Action<U> action) {
5684 >            super(m, p, b);
5685 >            this.transformer = transformer; this.action = action;
5686 >        }
5687 >        @SuppressWarnings("unchecked") public final void compute() {
5688 >            final Fun<? super V, ? extends U> transformer;
5689 >            final Action<U> action;
5690 >            if ((transformer = this.transformer) != null &&
5691 >                (action = this.action) != null) {
5692 >                for (int b; (b = preSplit()) > 0;)
5693 >                    new ForEachTransformedValueTask<K,V,U>
5694 >                        (map, this, b, transformer, action).fork();
5695 >                V v; U u;
5696 >                while ((v = advance()) != null) {
5697 >                    if ((u = transformer.apply(v)) != null)
5698 >                        action.apply(u);
5699 >                }
5700 >                propagateCompletion();
5701 >            }
5702 >        }
5703 >    }
5704 >
5705 >    @SuppressWarnings("serial") static final class ForEachTransformedEntryTask<K,V,U>
5706 >        extends Traverser<K,V,Void> {
5707 >        final Fun<Map.Entry<K,V>, ? extends U> transformer;
5708 >        final Action<U> action;
5709 >        ForEachTransformedEntryTask
5710 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5711 >             Fun<Map.Entry<K,V>, ? extends U> transformer, Action<U> action) {
5712 >            super(m, p, b);
5713 >            this.transformer = transformer; this.action = action;
5714 >        }
5715 >        @SuppressWarnings("unchecked") public final void compute() {
5716 >            final Fun<Map.Entry<K,V>, ? extends U> transformer;
5717 >            final Action<U> action;
5718 >            if ((transformer = this.transformer) != null &&
5719 >                (action = this.action) != null) {
5720 >                for (int b; (b = preSplit()) > 0;)
5721 >                    new ForEachTransformedEntryTask<K,V,U>
5722 >                        (map, this, b, transformer, action).fork();
5723 >                V v; U u;
5724 >                while ((v = advance()) != null) {
5725 >                    if ((u = transformer.apply(entryFor((K)nextKey,
5726 >                                                        v))) != null)
5727 >                        action.apply(u);
5728 >                }
5729 >                propagateCompletion();
5730 >            }
5731 >        }
5732 >    }
5733 >
5734 >    @SuppressWarnings("serial") static final class ForEachTransformedMappingTask<K,V,U>
5735 >        extends Traverser<K,V,Void> {
5736 >        final BiFun<? super K, ? super V, ? extends U> transformer;
5737 >        final Action<U> action;
5738 >        ForEachTransformedMappingTask
5739 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5740 >             BiFun<? super K, ? super V, ? extends U> transformer,
5741 >             Action<U> action) {
5742 >            super(m, p, b);
5743 >            this.transformer = transformer; this.action = action;
5744 >        }
5745 >        @SuppressWarnings("unchecked") public final void compute() {
5746 >            final BiFun<? super K, ? super V, ? extends U> transformer;
5747 >            final Action<U> action;
5748 >            if ((transformer = this.transformer) != null &&
5749 >                (action = this.action) != null) {
5750 >                for (int b; (b = preSplit()) > 0;)
5751 >                    new ForEachTransformedMappingTask<K,V,U>
5752 >                        (map, this, b, transformer, action).fork();
5753 >                V v; U u;
5754 >                while ((v = advance()) != null) {
5755 >                    if ((u = transformer.apply((K)nextKey, v)) != null)
5756 >                        action.apply(u);
5757 >                }
5758 >                propagateCompletion();
5759 >            }
5760 >        }
5761 >    }
5762 >
5763 >    @SuppressWarnings("serial") static final class SearchKeysTask<K,V,U>
5764 >        extends Traverser<K,V,U> {
5765 >        final Fun<? super K, ? extends U> searchFunction;
5766 >        final AtomicReference<U> result;
5767 >        SearchKeysTask
5768 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5769 >             Fun<? super K, ? extends U> searchFunction,
5770 >             AtomicReference<U> result) {
5771 >            super(m, p, b);
5772 >            this.searchFunction = searchFunction; this.result = result;
5773 >        }
5774 >        public final U getRawResult() { return result.get(); }
5775 >        @SuppressWarnings("unchecked") public final void compute() {
5776 >            final Fun<? super K, ? extends U> searchFunction;
5777 >            final AtomicReference<U> result;
5778 >            if ((searchFunction = this.searchFunction) != null &&
5779 >                (result = this.result) != null) {
5780 >                for (int b;;) {
5781 >                    if (result.get() != null)
5782 >                        return;
5783 >                    if ((b = preSplit()) <= 0)
5784 >                        break;
5785 >                    new SearchKeysTask<K,V,U>
5786 >                        (map, this, b, searchFunction, result).fork();
5787 >                }
5788 >                while (result.get() == null) {
5789 >                    U u;
5790 >                    if (advance() == null) {
5791 >                        propagateCompletion();
5792 >                        break;
5793 >                    }
5794 >                    if ((u = searchFunction.apply((K)nextKey)) != null) {
5795 >                        if (result.compareAndSet(null, u))
5796 >                            quietlyCompleteRoot();
5797 >                        break;
5798 >                    }
5799 >                }
5800 >            }
5801 >        }
5802 >    }
5803 >
5804 >    @SuppressWarnings("serial") static final class SearchValuesTask<K,V,U>
5805 >        extends Traverser<K,V,U> {
5806 >        final Fun<? super V, ? extends U> searchFunction;
5807 >        final AtomicReference<U> result;
5808 >        SearchValuesTask
5809 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5810 >             Fun<? super V, ? extends U> searchFunction,
5811 >             AtomicReference<U> result) {
5812 >            super(m, p, b);
5813 >            this.searchFunction = searchFunction; this.result = result;
5814 >        }
5815 >        public final U getRawResult() { return result.get(); }
5816 >        @SuppressWarnings("unchecked") public final void compute() {
5817 >            final Fun<? super V, ? extends U> searchFunction;
5818 >            final AtomicReference<U> result;
5819 >            if ((searchFunction = this.searchFunction) != null &&
5820 >                (result = this.result) != null) {
5821 >                for (int b;;) {
5822 >                    if (result.get() != null)
5823 >                        return;
5824 >                    if ((b = preSplit()) <= 0)
5825 >                        break;
5826 >                    new SearchValuesTask<K,V,U>
5827 >                        (map, this, b, searchFunction, result).fork();
5828 >                }
5829 >                while (result.get() == null) {
5830 >                    V v; U u;
5831 >                    if ((v = advance()) == null) {
5832 >                        propagateCompletion();
5833 >                        break;
5834 >                    }
5835 >                    if ((u = searchFunction.apply(v)) != null) {
5836 >                        if (result.compareAndSet(null, u))
5837 >                            quietlyCompleteRoot();
5838 >                        break;
5839 >                    }
5840 >                }
5841 >            }
5842 >        }
5843 >    }
5844 >
5845 >    @SuppressWarnings("serial") static final class SearchEntriesTask<K,V,U>
5846 >        extends Traverser<K,V,U> {
5847 >        final Fun<Entry<K,V>, ? extends U> searchFunction;
5848 >        final AtomicReference<U> result;
5849 >        SearchEntriesTask
5850 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5851 >             Fun<Entry<K,V>, ? extends U> searchFunction,
5852 >             AtomicReference<U> result) {
5853 >            super(m, p, b);
5854 >            this.searchFunction = searchFunction; this.result = result;
5855 >        }
5856 >        public final U getRawResult() { return result.get(); }
5857 >        @SuppressWarnings("unchecked") public final void compute() {
5858 >            final Fun<Entry<K,V>, ? extends U> searchFunction;
5859 >            final AtomicReference<U> result;
5860 >            if ((searchFunction = this.searchFunction) != null &&
5861 >                (result = this.result) != null) {
5862 >                for (int b;;) {
5863 >                    if (result.get() != null)
5864 >                        return;
5865 >                    if ((b = preSplit()) <= 0)
5866 >                        break;
5867 >                    new SearchEntriesTask<K,V,U>
5868 >                        (map, this, b, searchFunction, result).fork();
5869 >                }
5870 >                while (result.get() == null) {
5871 >                    V v; U u;
5872 >                    if ((v = advance()) == null) {
5873 >                        propagateCompletion();
5874 >                        break;
5875 >                    }
5876 >                    if ((u = searchFunction.apply(entryFor((K)nextKey,
5877 >                                                           v))) != null) {
5878 >                        if (result.compareAndSet(null, u))
5879 >                            quietlyCompleteRoot();
5880 >                        return;
5881 >                    }
5882 >                }
5883 >            }
5884 >        }
5885 >    }
5886 >
5887 >    @SuppressWarnings("serial") static final class SearchMappingsTask<K,V,U>
5888 >        extends Traverser<K,V,U> {
5889 >        final BiFun<? super K, ? super V, ? extends U> searchFunction;
5890 >        final AtomicReference<U> result;
5891 >        SearchMappingsTask
5892 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5893 >             BiFun<? super K, ? super V, ? extends U> searchFunction,
5894 >             AtomicReference<U> result) {
5895 >            super(m, p, b);
5896 >            this.searchFunction = searchFunction; this.result = result;
5897 >        }
5898 >        public final U getRawResult() { return result.get(); }
5899 >        @SuppressWarnings("unchecked") public final void compute() {
5900 >            final BiFun<? super K, ? super V, ? extends U> searchFunction;
5901 >            final AtomicReference<U> result;
5902 >            if ((searchFunction = this.searchFunction) != null &&
5903 >                (result = this.result) != null) {
5904 >                for (int b;;) {
5905 >                    if (result.get() != null)
5906 >                        return;
5907 >                    if ((b = preSplit()) <= 0)
5908 >                        break;
5909 >                    new SearchMappingsTask<K,V,U>
5910 >                        (map, this, b, searchFunction, result).fork();
5911 >                }
5912 >                while (result.get() == null) {
5913 >                    V v; U u;
5914 >                    if ((v = advance()) == null) {
5915 >                        propagateCompletion();
5916 >                        break;
5917 >                    }
5918 >                    if ((u = searchFunction.apply((K)nextKey, v)) != null) {
5919 >                        if (result.compareAndSet(null, u))
5920 >                            quietlyCompleteRoot();
5921 >                        break;
5922 >                    }
5923 >                }
5924 >            }
5925 >        }
5926 >    }
5927 >
5928 >    @SuppressWarnings("serial") static final class ReduceKeysTask<K,V>
5929 >        extends Traverser<K,V,K> {
5930 >        final BiFun<? super K, ? super K, ? extends K> reducer;
5931 >        K result;
5932 >        ReduceKeysTask<K,V> rights, nextRight;
5933 >        ReduceKeysTask
5934 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5935 >             ReduceKeysTask<K,V> nextRight,
5936 >             BiFun<? super K, ? super K, ? extends K> reducer) {
5937 >            super(m, p, b); this.nextRight = nextRight;
5938 >            this.reducer = reducer;
5939 >        }
5940 >        public final K getRawResult() { return result; }
5941 >        @SuppressWarnings("unchecked") public final void compute() {
5942 >            final BiFun<? super K, ? super K, ? extends K> reducer;
5943 >            if ((reducer = this.reducer) != null) {
5944 >                for (int b; (b = preSplit()) > 0;)
5945 >                    (rights = new ReduceKeysTask<K,V>
5946 >                     (map, this, b, rights, reducer)).fork();
5947 >                K r = null;
5948 >                while (advance() != null) {
5949 >                    K u = (K)nextKey;
5950 >                    r = (r == null) ? u : reducer.apply(r, u);
5951 >                }
5952 >                result = r;
5953 >                CountedCompleter<?> c;
5954 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5955 >                    ReduceKeysTask<K,V>
5956 >                        t = (ReduceKeysTask<K,V>)c,
5957 >                        s = t.rights;
5958 >                    while (s != null) {
5959 >                        K tr, sr;
5960 >                        if ((sr = s.result) != null)
5961 >                            t.result = (((tr = t.result) == null) ? sr :
5962 >                                        reducer.apply(tr, sr));
5963 >                        s = t.rights = s.nextRight;
5964 >                    }
5965 >                }
5966 >            }
5967 >        }
5968 >    }
5969 >
5970 >    @SuppressWarnings("serial") static final class ReduceValuesTask<K,V>
5971 >        extends Traverser<K,V,V> {
5972 >        final BiFun<? super V, ? super V, ? extends V> reducer;
5973 >        V result;
5974 >        ReduceValuesTask<K,V> rights, nextRight;
5975 >        ReduceValuesTask
5976 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
5977 >             ReduceValuesTask<K,V> nextRight,
5978 >             BiFun<? super V, ? super V, ? extends V> reducer) {
5979 >            super(m, p, b); this.nextRight = nextRight;
5980 >            this.reducer = reducer;
5981 >        }
5982 >        public final V getRawResult() { return result; }
5983 >        @SuppressWarnings("unchecked") public final void compute() {
5984 >            final BiFun<? super V, ? super V, ? extends V> reducer;
5985 >            if ((reducer = this.reducer) != null) {
5986 >                for (int b; (b = preSplit()) > 0;)
5987 >                    (rights = new ReduceValuesTask<K,V>
5988 >                     (map, this, b, rights, reducer)).fork();
5989 >                V r = null;
5990 >                V v;
5991 >                while ((v = advance()) != null) {
5992 >                    V u = v;
5993 >                    r = (r == null) ? u : reducer.apply(r, u);
5994 >                }
5995 >                result = r;
5996 >                CountedCompleter<?> c;
5997 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
5998 >                    ReduceValuesTask<K,V>
5999 >                        t = (ReduceValuesTask<K,V>)c,
6000 >                        s = t.rights;
6001 >                    while (s != null) {
6002 >                        V tr, sr;
6003 >                        if ((sr = s.result) != null)
6004 >                            t.result = (((tr = t.result) == null) ? sr :
6005 >                                        reducer.apply(tr, sr));
6006 >                        s = t.rights = s.nextRight;
6007 >                    }
6008 >                }
6009 >            }
6010 >        }
6011 >    }
6012 >
6013 >    @SuppressWarnings("serial") static final class ReduceEntriesTask<K,V>
6014 >        extends Traverser<K,V,Map.Entry<K,V>> {
6015 >        final BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
6016 >        Map.Entry<K,V> result;
6017 >        ReduceEntriesTask<K,V> rights, nextRight;
6018 >        ReduceEntriesTask
6019 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6020 >             ReduceEntriesTask<K,V> nextRight,
6021 >             BiFun<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
6022 >            super(m, p, b); this.nextRight = nextRight;
6023 >            this.reducer = reducer;
6024 >        }
6025 >        public final Map.Entry<K,V> getRawResult() { return result; }
6026 >        @SuppressWarnings("unchecked") public final void compute() {
6027 >            final BiFun<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
6028 >            if ((reducer = this.reducer) != null) {
6029 >                for (int b; (b = preSplit()) > 0;)
6030 >                    (rights = new ReduceEntriesTask<K,V>
6031 >                     (map, this, b, rights, reducer)).fork();
6032 >                Map.Entry<K,V> r = null;
6033 >                V v;
6034 >                while ((v = advance()) != null) {
6035 >                    Map.Entry<K,V> u = entryFor((K)nextKey, v);
6036 >                    r = (r == null) ? u : reducer.apply(r, u);
6037 >                }
6038 >                result = r;
6039 >                CountedCompleter<?> c;
6040 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6041 >                    ReduceEntriesTask<K,V>
6042 >                        t = (ReduceEntriesTask<K,V>)c,
6043 >                        s = t.rights;
6044 >                    while (s != null) {
6045 >                        Map.Entry<K,V> tr, sr;
6046 >                        if ((sr = s.result) != null)
6047 >                            t.result = (((tr = t.result) == null) ? sr :
6048 >                                        reducer.apply(tr, sr));
6049 >                        s = t.rights = s.nextRight;
6050 >                    }
6051 >                }
6052 >            }
6053 >        }
6054 >    }
6055 >
6056 >    @SuppressWarnings("serial") static final class MapReduceKeysTask<K,V,U>
6057 >        extends Traverser<K,V,U> {
6058 >        final Fun<? super K, ? extends U> transformer;
6059 >        final BiFun<? super U, ? super U, ? extends U> reducer;
6060 >        U result;
6061 >        MapReduceKeysTask<K,V,U> rights, nextRight;
6062 >        MapReduceKeysTask
6063 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6064 >             MapReduceKeysTask<K,V,U> nextRight,
6065 >             Fun<? super K, ? extends U> transformer,
6066 >             BiFun<? super U, ? super U, ? extends U> reducer) {
6067 >            super(m, p, b); this.nextRight = nextRight;
6068 >            this.transformer = transformer;
6069 >            this.reducer = reducer;
6070 >        }
6071 >        public final U getRawResult() { return result; }
6072 >        @SuppressWarnings("unchecked") public final void compute() {
6073 >            final Fun<? super K, ? extends U> transformer;
6074 >            final BiFun<? super U, ? super U, ? extends U> reducer;
6075 >            if ((transformer = this.transformer) != null &&
6076 >                (reducer = this.reducer) != null) {
6077 >                for (int b; (b = preSplit()) > 0;)
6078 >                    (rights = new MapReduceKeysTask<K,V,U>
6079 >                     (map, this, b, rights, transformer, reducer)).fork();
6080 >                U r = null, u;
6081 >                while (advance() != null) {
6082 >                    if ((u = transformer.apply((K)nextKey)) != null)
6083 >                        r = (r == null) ? u : reducer.apply(r, u);
6084 >                }
6085 >                result = r;
6086 >                CountedCompleter<?> c;
6087 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6088 >                    MapReduceKeysTask<K,V,U>
6089 >                        t = (MapReduceKeysTask<K,V,U>)c,
6090 >                        s = t.rights;
6091 >                    while (s != null) {
6092 >                        U tr, sr;
6093 >                        if ((sr = s.result) != null)
6094 >                            t.result = (((tr = t.result) == null) ? sr :
6095 >                                        reducer.apply(tr, sr));
6096 >                        s = t.rights = s.nextRight;
6097 >                    }
6098 >                }
6099 >            }
6100 >        }
6101 >    }
6102 >
6103 >    @SuppressWarnings("serial") static final class MapReduceValuesTask<K,V,U>
6104 >        extends Traverser<K,V,U> {
6105 >        final Fun<? super V, ? extends U> transformer;
6106 >        final BiFun<? super U, ? super U, ? extends U> reducer;
6107 >        U result;
6108 >        MapReduceValuesTask<K,V,U> rights, nextRight;
6109 >        MapReduceValuesTask
6110 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6111 >             MapReduceValuesTask<K,V,U> nextRight,
6112 >             Fun<? super V, ? extends U> transformer,
6113 >             BiFun<? super U, ? super U, ? extends U> reducer) {
6114 >            super(m, p, b); this.nextRight = nextRight;
6115 >            this.transformer = transformer;
6116 >            this.reducer = reducer;
6117 >        }
6118 >        public final U getRawResult() { return result; }
6119 >        @SuppressWarnings("unchecked") public final void compute() {
6120 >            final Fun<? super V, ? extends U> transformer;
6121 >            final BiFun<? super U, ? super U, ? extends U> reducer;
6122 >            if ((transformer = this.transformer) != null &&
6123 >                (reducer = this.reducer) != null) {
6124 >                for (int b; (b = preSplit()) > 0;)
6125 >                    (rights = new MapReduceValuesTask<K,V,U>
6126 >                     (map, this, b, rights, transformer, reducer)).fork();
6127 >                U r = null, u;
6128 >                V v;
6129 >                while ((v = advance()) != null) {
6130 >                    if ((u = transformer.apply(v)) != null)
6131 >                        r = (r == null) ? u : reducer.apply(r, u);
6132 >                }
6133 >                result = r;
6134 >                CountedCompleter<?> c;
6135 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6136 >                    MapReduceValuesTask<K,V,U>
6137 >                        t = (MapReduceValuesTask<K,V,U>)c,
6138 >                        s = t.rights;
6139 >                    while (s != null) {
6140 >                        U tr, sr;
6141 >                        if ((sr = s.result) != null)
6142 >                            t.result = (((tr = t.result) == null) ? sr :
6143 >                                        reducer.apply(tr, sr));
6144 >                        s = t.rights = s.nextRight;
6145 >                    }
6146 >                }
6147 >            }
6148 >        }
6149 >    }
6150 >
6151 >    @SuppressWarnings("serial") static final class MapReduceEntriesTask<K,V,U>
6152 >        extends Traverser<K,V,U> {
6153 >        final Fun<Map.Entry<K,V>, ? extends U> transformer;
6154 >        final BiFun<? super U, ? super U, ? extends U> reducer;
6155 >        U result;
6156 >        MapReduceEntriesTask<K,V,U> rights, nextRight;
6157 >        MapReduceEntriesTask
6158 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6159 >             MapReduceEntriesTask<K,V,U> nextRight,
6160 >             Fun<Map.Entry<K,V>, ? extends U> transformer,
6161 >             BiFun<? super U, ? super U, ? extends U> reducer) {
6162 >            super(m, p, b); this.nextRight = nextRight;
6163 >            this.transformer = transformer;
6164 >            this.reducer = reducer;
6165 >        }
6166 >        public final U getRawResult() { return result; }
6167 >        @SuppressWarnings("unchecked") public final void compute() {
6168 >            final Fun<Map.Entry<K,V>, ? extends U> transformer;
6169 >            final BiFun<? super U, ? super U, ? extends U> reducer;
6170 >            if ((transformer = this.transformer) != null &&
6171 >                (reducer = this.reducer) != null) {
6172 >                for (int b; (b = preSplit()) > 0;)
6173 >                    (rights = new MapReduceEntriesTask<K,V,U>
6174 >                     (map, this, b, rights, transformer, reducer)).fork();
6175 >                U r = null, u;
6176 >                V v;
6177 >                while ((v = advance()) != null) {
6178 >                    if ((u = transformer.apply(entryFor((K)nextKey,
6179 >                                                        v))) != null)
6180 >                        r = (r == null) ? u : reducer.apply(r, u);
6181 >                }
6182 >                result = r;
6183 >                CountedCompleter<?> c;
6184 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6185 >                    MapReduceEntriesTask<K,V,U>
6186 >                        t = (MapReduceEntriesTask<K,V,U>)c,
6187 >                        s = t.rights;
6188 >                    while (s != null) {
6189 >                        U tr, sr;
6190 >                        if ((sr = s.result) != null)
6191 >                            t.result = (((tr = t.result) == null) ? sr :
6192 >                                        reducer.apply(tr, sr));
6193 >                        s = t.rights = s.nextRight;
6194 >                    }
6195 >                }
6196 >            }
6197 >        }
6198 >    }
6199 >
6200 >    @SuppressWarnings("serial") static final class MapReduceMappingsTask<K,V,U>
6201 >        extends Traverser<K,V,U> {
6202 >        final BiFun<? super K, ? super V, ? extends U> transformer;
6203 >        final BiFun<? super U, ? super U, ? extends U> reducer;
6204 >        U result;
6205 >        MapReduceMappingsTask<K,V,U> rights, nextRight;
6206 >        MapReduceMappingsTask
6207 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6208 >             MapReduceMappingsTask<K,V,U> nextRight,
6209 >             BiFun<? super K, ? super V, ? extends U> transformer,
6210 >             BiFun<? super U, ? super U, ? extends U> reducer) {
6211 >            super(m, p, b); this.nextRight = nextRight;
6212 >            this.transformer = transformer;
6213 >            this.reducer = reducer;
6214 >        }
6215 >        public final U getRawResult() { return result; }
6216 >        @SuppressWarnings("unchecked") public final void compute() {
6217 >            final BiFun<? super K, ? super V, ? extends U> transformer;
6218 >            final BiFun<? super U, ? super U, ? extends U> reducer;
6219 >            if ((transformer = this.transformer) != null &&
6220 >                (reducer = this.reducer) != null) {
6221 >                for (int b; (b = preSplit()) > 0;)
6222 >                    (rights = new MapReduceMappingsTask<K,V,U>
6223 >                     (map, this, b, rights, transformer, reducer)).fork();
6224 >                U r = null, u;
6225 >                V v;
6226 >                while ((v = advance()) != null) {
6227 >                    if ((u = transformer.apply((K)nextKey, v)) != null)
6228 >                        r = (r == null) ? u : reducer.apply(r, u);
6229 >                }
6230 >                result = r;
6231 >                CountedCompleter<?> c;
6232 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6233 >                    MapReduceMappingsTask<K,V,U>
6234 >                        t = (MapReduceMappingsTask<K,V,U>)c,
6235 >                        s = t.rights;
6236 >                    while (s != null) {
6237 >                        U tr, sr;
6238 >                        if ((sr = s.result) != null)
6239 >                            t.result = (((tr = t.result) == null) ? sr :
6240 >                                        reducer.apply(tr, sr));
6241 >                        s = t.rights = s.nextRight;
6242 >                    }
6243 >                }
6244 >            }
6245 >        }
6246 >    }
6247 >
6248 >    @SuppressWarnings("serial") static final class MapReduceKeysToDoubleTask<K,V>
6249 >        extends Traverser<K,V,Double> {
6250 >        final ObjectToDouble<? super K> transformer;
6251 >        final DoubleByDoubleToDouble reducer;
6252 >        final double basis;
6253 >        double result;
6254 >        MapReduceKeysToDoubleTask<K,V> rights, nextRight;
6255 >        MapReduceKeysToDoubleTask
6256 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6257 >             MapReduceKeysToDoubleTask<K,V> nextRight,
6258 >             ObjectToDouble<? super K> transformer,
6259 >             double basis,
6260 >             DoubleByDoubleToDouble reducer) {
6261 >            super(m, p, b); this.nextRight = nextRight;
6262 >            this.transformer = transformer;
6263 >            this.basis = basis; this.reducer = reducer;
6264 >        }
6265 >        public final Double getRawResult() { return result; }
6266 >        @SuppressWarnings("unchecked") public final void compute() {
6267 >            final ObjectToDouble<? super K> transformer;
6268 >            final DoubleByDoubleToDouble reducer;
6269 >            if ((transformer = this.transformer) != null &&
6270 >                (reducer = this.reducer) != null) {
6271 >                double r = this.basis;
6272 >                for (int b; (b = preSplit()) > 0;)
6273 >                    (rights = new MapReduceKeysToDoubleTask<K,V>
6274 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6275 >                while (advance() != null)
6276 >                    r = reducer.apply(r, transformer.apply((K)nextKey));
6277 >                result = r;
6278 >                CountedCompleter<?> c;
6279 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6280 >                    MapReduceKeysToDoubleTask<K,V>
6281 >                        t = (MapReduceKeysToDoubleTask<K,V>)c,
6282 >                        s = t.rights;
6283 >                    while (s != null) {
6284 >                        t.result = reducer.apply(t.result, s.result);
6285 >                        s = t.rights = s.nextRight;
6286 >                    }
6287 >                }
6288 >            }
6289 >        }
6290 >    }
6291 >
6292 >    @SuppressWarnings("serial") static final class MapReduceValuesToDoubleTask<K,V>
6293 >        extends Traverser<K,V,Double> {
6294 >        final ObjectToDouble<? super V> transformer;
6295 >        final DoubleByDoubleToDouble reducer;
6296 >        final double basis;
6297 >        double result;
6298 >        MapReduceValuesToDoubleTask<K,V> rights, nextRight;
6299 >        MapReduceValuesToDoubleTask
6300 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6301 >             MapReduceValuesToDoubleTask<K,V> nextRight,
6302 >             ObjectToDouble<? super V> transformer,
6303 >             double basis,
6304 >             DoubleByDoubleToDouble reducer) {
6305 >            super(m, p, b); this.nextRight = nextRight;
6306 >            this.transformer = transformer;
6307 >            this.basis = basis; this.reducer = reducer;
6308 >        }
6309 >        public final Double getRawResult() { return result; }
6310 >        @SuppressWarnings("unchecked") public final void compute() {
6311 >            final ObjectToDouble<? super V> transformer;
6312 >            final DoubleByDoubleToDouble reducer;
6313 >            if ((transformer = this.transformer) != null &&
6314 >                (reducer = this.reducer) != null) {
6315 >                double r = this.basis;
6316 >                for (int b; (b = preSplit()) > 0;)
6317 >                    (rights = new MapReduceValuesToDoubleTask<K,V>
6318 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6319 >                V v;
6320 >                while ((v = advance()) != null)
6321 >                    r = reducer.apply(r, transformer.apply(v));
6322 >                result = r;
6323 >                CountedCompleter<?> c;
6324 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6325 >                    MapReduceValuesToDoubleTask<K,V>
6326 >                        t = (MapReduceValuesToDoubleTask<K,V>)c,
6327 >                        s = t.rights;
6328 >                    while (s != null) {
6329 >                        t.result = reducer.apply(t.result, s.result);
6330 >                        s = t.rights = s.nextRight;
6331 >                    }
6332 >                }
6333 >            }
6334 >        }
6335 >    }
6336 >
6337 >    @SuppressWarnings("serial") static final class MapReduceEntriesToDoubleTask<K,V>
6338 >        extends Traverser<K,V,Double> {
6339 >        final ObjectToDouble<Map.Entry<K,V>> transformer;
6340 >        final DoubleByDoubleToDouble reducer;
6341 >        final double basis;
6342 >        double result;
6343 >        MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
6344 >        MapReduceEntriesToDoubleTask
6345 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6346 >             MapReduceEntriesToDoubleTask<K,V> nextRight,
6347 >             ObjectToDouble<Map.Entry<K,V>> transformer,
6348 >             double basis,
6349 >             DoubleByDoubleToDouble reducer) {
6350 >            super(m, p, b); this.nextRight = nextRight;
6351 >            this.transformer = transformer;
6352 >            this.basis = basis; this.reducer = reducer;
6353 >        }
6354 >        public final Double getRawResult() { return result; }
6355 >        @SuppressWarnings("unchecked") public final void compute() {
6356 >            final ObjectToDouble<Map.Entry<K,V>> transformer;
6357 >            final DoubleByDoubleToDouble reducer;
6358 >            if ((transformer = this.transformer) != null &&
6359 >                (reducer = this.reducer) != null) {
6360 >                double r = this.basis;
6361 >                for (int b; (b = preSplit()) > 0;)
6362 >                    (rights = new MapReduceEntriesToDoubleTask<K,V>
6363 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6364 >                V v;
6365 >                while ((v = advance()) != null)
6366 >                    r = reducer.apply(r, transformer.apply(entryFor((K)nextKey,
6367 >                                                                    v)));
6368 >                result = r;
6369 >                CountedCompleter<?> c;
6370 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6371 >                    MapReduceEntriesToDoubleTask<K,V>
6372 >                        t = (MapReduceEntriesToDoubleTask<K,V>)c,
6373 >                        s = t.rights;
6374 >                    while (s != null) {
6375 >                        t.result = reducer.apply(t.result, s.result);
6376 >                        s = t.rights = s.nextRight;
6377 >                    }
6378 >                }
6379 >            }
6380 >        }
6381 >    }
6382 >
6383 >    @SuppressWarnings("serial") static final class MapReduceMappingsToDoubleTask<K,V>
6384 >        extends Traverser<K,V,Double> {
6385 >        final ObjectByObjectToDouble<? super K, ? super V> transformer;
6386 >        final DoubleByDoubleToDouble reducer;
6387 >        final double basis;
6388 >        double result;
6389 >        MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
6390 >        MapReduceMappingsToDoubleTask
6391 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6392 >             MapReduceMappingsToDoubleTask<K,V> nextRight,
6393 >             ObjectByObjectToDouble<? super K, ? super V> transformer,
6394 >             double basis,
6395 >             DoubleByDoubleToDouble reducer) {
6396 >            super(m, p, b); this.nextRight = nextRight;
6397 >            this.transformer = transformer;
6398 >            this.basis = basis; this.reducer = reducer;
6399 >        }
6400 >        public final Double getRawResult() { return result; }
6401 >        @SuppressWarnings("unchecked") public final void compute() {
6402 >            final ObjectByObjectToDouble<? super K, ? super V> transformer;
6403 >            final DoubleByDoubleToDouble reducer;
6404 >            if ((transformer = this.transformer) != null &&
6405 >                (reducer = this.reducer) != null) {
6406 >                double r = this.basis;
6407 >                for (int b; (b = preSplit()) > 0;)
6408 >                    (rights = new MapReduceMappingsToDoubleTask<K,V>
6409 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6410 >                V v;
6411 >                while ((v = advance()) != null)
6412 >                    r = reducer.apply(r, transformer.apply((K)nextKey, v));
6413 >                result = r;
6414 >                CountedCompleter<?> c;
6415 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6416 >                    MapReduceMappingsToDoubleTask<K,V>
6417 >                        t = (MapReduceMappingsToDoubleTask<K,V>)c,
6418 >                        s = t.rights;
6419 >                    while (s != null) {
6420 >                        t.result = reducer.apply(t.result, s.result);
6421 >                        s = t.rights = s.nextRight;
6422 >                    }
6423 >                }
6424 >            }
6425 >        }
6426 >    }
6427 >
6428 >    @SuppressWarnings("serial") static final class MapReduceKeysToLongTask<K,V>
6429 >        extends Traverser<K,V,Long> {
6430 >        final ObjectToLong<? super K> transformer;
6431 >        final LongByLongToLong reducer;
6432 >        final long basis;
6433 >        long result;
6434 >        MapReduceKeysToLongTask<K,V> rights, nextRight;
6435 >        MapReduceKeysToLongTask
6436 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6437 >             MapReduceKeysToLongTask<K,V> nextRight,
6438 >             ObjectToLong<? super K> transformer,
6439 >             long basis,
6440 >             LongByLongToLong reducer) {
6441 >            super(m, p, b); this.nextRight = nextRight;
6442 >            this.transformer = transformer;
6443 >            this.basis = basis; this.reducer = reducer;
6444 >        }
6445 >        public final Long getRawResult() { return result; }
6446 >        @SuppressWarnings("unchecked") public final void compute() {
6447 >            final ObjectToLong<? super K> transformer;
6448 >            final LongByLongToLong reducer;
6449 >            if ((transformer = this.transformer) != null &&
6450 >                (reducer = this.reducer) != null) {
6451 >                long r = this.basis;
6452 >                for (int b; (b = preSplit()) > 0;)
6453 >                    (rights = new MapReduceKeysToLongTask<K,V>
6454 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6455 >                while (advance() != null)
6456 >                    r = reducer.apply(r, transformer.apply((K)nextKey));
6457 >                result = r;
6458 >                CountedCompleter<?> c;
6459 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6460 >                    MapReduceKeysToLongTask<K,V>
6461 >                        t = (MapReduceKeysToLongTask<K,V>)c,
6462 >                        s = t.rights;
6463 >                    while (s != null) {
6464 >                        t.result = reducer.apply(t.result, s.result);
6465 >                        s = t.rights = s.nextRight;
6466 >                    }
6467 >                }
6468 >            }
6469 >        }
6470 >    }
6471 >
6472 >    @SuppressWarnings("serial") static final class MapReduceValuesToLongTask<K,V>
6473 >        extends Traverser<K,V,Long> {
6474 >        final ObjectToLong<? super V> transformer;
6475 >        final LongByLongToLong reducer;
6476 >        final long basis;
6477 >        long result;
6478 >        MapReduceValuesToLongTask<K,V> rights, nextRight;
6479 >        MapReduceValuesToLongTask
6480 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6481 >             MapReduceValuesToLongTask<K,V> nextRight,
6482 >             ObjectToLong<? super V> transformer,
6483 >             long basis,
6484 >             LongByLongToLong reducer) {
6485 >            super(m, p, b); this.nextRight = nextRight;
6486 >            this.transformer = transformer;
6487 >            this.basis = basis; this.reducer = reducer;
6488 >        }
6489 >        public final Long getRawResult() { return result; }
6490 >        @SuppressWarnings("unchecked") public final void compute() {
6491 >            final ObjectToLong<? super V> transformer;
6492 >            final LongByLongToLong reducer;
6493 >            if ((transformer = this.transformer) != null &&
6494 >                (reducer = this.reducer) != null) {
6495 >                long r = this.basis;
6496 >                for (int b; (b = preSplit()) > 0;)
6497 >                    (rights = new MapReduceValuesToLongTask<K,V>
6498 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6499 >                V v;
6500 >                while ((v = advance()) != null)
6501 >                    r = reducer.apply(r, transformer.apply(v));
6502 >                result = r;
6503 >                CountedCompleter<?> c;
6504 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6505 >                    MapReduceValuesToLongTask<K,V>
6506 >                        t = (MapReduceValuesToLongTask<K,V>)c,
6507 >                        s = t.rights;
6508 >                    while (s != null) {
6509 >                        t.result = reducer.apply(t.result, s.result);
6510 >                        s = t.rights = s.nextRight;
6511 >                    }
6512 >                }
6513 >            }
6514 >        }
6515 >    }
6516 >
6517 >    @SuppressWarnings("serial") static final class MapReduceEntriesToLongTask<K,V>
6518 >        extends Traverser<K,V,Long> {
6519 >        final ObjectToLong<Map.Entry<K,V>> transformer;
6520 >        final LongByLongToLong reducer;
6521 >        final long basis;
6522 >        long result;
6523 >        MapReduceEntriesToLongTask<K,V> rights, nextRight;
6524 >        MapReduceEntriesToLongTask
6525 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6526 >             MapReduceEntriesToLongTask<K,V> nextRight,
6527 >             ObjectToLong<Map.Entry<K,V>> transformer,
6528 >             long basis,
6529 >             LongByLongToLong reducer) {
6530 >            super(m, p, b); this.nextRight = nextRight;
6531 >            this.transformer = transformer;
6532 >            this.basis = basis; this.reducer = reducer;
6533 >        }
6534 >        public final Long getRawResult() { return result; }
6535 >        @SuppressWarnings("unchecked") public final void compute() {
6536 >            final ObjectToLong<Map.Entry<K,V>> transformer;
6537 >            final LongByLongToLong reducer;
6538 >            if ((transformer = this.transformer) != null &&
6539 >                (reducer = this.reducer) != null) {
6540 >                long r = this.basis;
6541 >                for (int b; (b = preSplit()) > 0;)
6542 >                    (rights = new MapReduceEntriesToLongTask<K,V>
6543 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6544 >                V v;
6545 >                while ((v = advance()) != null)
6546 >                    r = reducer.apply(r, transformer.apply(entryFor((K)nextKey,
6547 >                                                                    v)));
6548 >                result = r;
6549 >                CountedCompleter<?> c;
6550 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6551 >                    MapReduceEntriesToLongTask<K,V>
6552 >                        t = (MapReduceEntriesToLongTask<K,V>)c,
6553 >                        s = t.rights;
6554 >                    while (s != null) {
6555 >                        t.result = reducer.apply(t.result, s.result);
6556 >                        s = t.rights = s.nextRight;
6557 >                    }
6558 >                }
6559 >            }
6560 >        }
6561 >    }
6562 >
6563 >    @SuppressWarnings("serial") static final class MapReduceMappingsToLongTask<K,V>
6564 >        extends Traverser<K,V,Long> {
6565 >        final ObjectByObjectToLong<? super K, ? super V> transformer;
6566 >        final LongByLongToLong reducer;
6567 >        final long basis;
6568 >        long result;
6569 >        MapReduceMappingsToLongTask<K,V> rights, nextRight;
6570 >        MapReduceMappingsToLongTask
6571 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6572 >             MapReduceMappingsToLongTask<K,V> nextRight,
6573 >             ObjectByObjectToLong<? super K, ? super V> transformer,
6574 >             long basis,
6575 >             LongByLongToLong reducer) {
6576 >            super(m, p, b); this.nextRight = nextRight;
6577 >            this.transformer = transformer;
6578 >            this.basis = basis; this.reducer = reducer;
6579 >        }
6580 >        public final Long getRawResult() { return result; }
6581 >        @SuppressWarnings("unchecked") public final void compute() {
6582 >            final ObjectByObjectToLong<? super K, ? super V> transformer;
6583 >            final LongByLongToLong reducer;
6584 >            if ((transformer = this.transformer) != null &&
6585 >                (reducer = this.reducer) != null) {
6586 >                long r = this.basis;
6587 >                for (int b; (b = preSplit()) > 0;)
6588 >                    (rights = new MapReduceMappingsToLongTask<K,V>
6589 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6590 >                V v;
6591 >                while ((v = advance()) != null)
6592 >                    r = reducer.apply(r, transformer.apply((K)nextKey, v));
6593 >                result = r;
6594 >                CountedCompleter<?> c;
6595 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6596 >                    MapReduceMappingsToLongTask<K,V>
6597 >                        t = (MapReduceMappingsToLongTask<K,V>)c,
6598 >                        s = t.rights;
6599 >                    while (s != null) {
6600 >                        t.result = reducer.apply(t.result, s.result);
6601 >                        s = t.rights = s.nextRight;
6602 >                    }
6603 >                }
6604 >            }
6605 >        }
6606 >    }
6607 >
6608 >    @SuppressWarnings("serial") static final class MapReduceKeysToIntTask<K,V>
6609 >        extends Traverser<K,V,Integer> {
6610 >        final ObjectToInt<? super K> transformer;
6611 >        final IntByIntToInt reducer;
6612 >        final int basis;
6613 >        int result;
6614 >        MapReduceKeysToIntTask<K,V> rights, nextRight;
6615 >        MapReduceKeysToIntTask
6616 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6617 >             MapReduceKeysToIntTask<K,V> nextRight,
6618 >             ObjectToInt<? super K> transformer,
6619 >             int basis,
6620 >             IntByIntToInt reducer) {
6621 >            super(m, p, b); this.nextRight = nextRight;
6622 >            this.transformer = transformer;
6623 >            this.basis = basis; this.reducer = reducer;
6624 >        }
6625 >        public final Integer getRawResult() { return result; }
6626 >        @SuppressWarnings("unchecked") public final void compute() {
6627 >            final ObjectToInt<? super K> transformer;
6628 >            final IntByIntToInt reducer;
6629 >            if ((transformer = this.transformer) != null &&
6630 >                (reducer = this.reducer) != null) {
6631 >                int r = this.basis;
6632 >                for (int b; (b = preSplit()) > 0;)
6633 >                    (rights = new MapReduceKeysToIntTask<K,V>
6634 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6635 >                while (advance() != null)
6636 >                    r = reducer.apply(r, transformer.apply((K)nextKey));
6637 >                result = r;
6638 >                CountedCompleter<?> c;
6639 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6640 >                    MapReduceKeysToIntTask<K,V>
6641 >                        t = (MapReduceKeysToIntTask<K,V>)c,
6642 >                        s = t.rights;
6643 >                    while (s != null) {
6644 >                        t.result = reducer.apply(t.result, s.result);
6645 >                        s = t.rights = s.nextRight;
6646 >                    }
6647 >                }
6648 >            }
6649 >        }
6650 >    }
6651 >
6652 >    @SuppressWarnings("serial") static final class MapReduceValuesToIntTask<K,V>
6653 >        extends Traverser<K,V,Integer> {
6654 >        final ObjectToInt<? super V> transformer;
6655 >        final IntByIntToInt reducer;
6656 >        final int basis;
6657 >        int result;
6658 >        MapReduceValuesToIntTask<K,V> rights, nextRight;
6659 >        MapReduceValuesToIntTask
6660 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6661 >             MapReduceValuesToIntTask<K,V> nextRight,
6662 >             ObjectToInt<? super V> transformer,
6663 >             int basis,
6664 >             IntByIntToInt reducer) {
6665 >            super(m, p, b); this.nextRight = nextRight;
6666 >            this.transformer = transformer;
6667 >            this.basis = basis; this.reducer = reducer;
6668 >        }
6669 >        public final Integer getRawResult() { return result; }
6670 >        @SuppressWarnings("unchecked") public final void compute() {
6671 >            final ObjectToInt<? super V> transformer;
6672 >            final IntByIntToInt reducer;
6673 >            if ((transformer = this.transformer) != null &&
6674 >                (reducer = this.reducer) != null) {
6675 >                int r = this.basis;
6676 >                for (int b; (b = preSplit()) > 0;)
6677 >                    (rights = new MapReduceValuesToIntTask<K,V>
6678 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6679 >                V v;
6680 >                while ((v = advance()) != null)
6681 >                    r = reducer.apply(r, transformer.apply(v));
6682 >                result = r;
6683 >                CountedCompleter<?> c;
6684 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6685 >                    MapReduceValuesToIntTask<K,V>
6686 >                        t = (MapReduceValuesToIntTask<K,V>)c,
6687 >                        s = t.rights;
6688 >                    while (s != null) {
6689 >                        t.result = reducer.apply(t.result, s.result);
6690 >                        s = t.rights = s.nextRight;
6691 >                    }
6692 >                }
6693 >            }
6694 >        }
6695 >    }
6696 >
6697 >    @SuppressWarnings("serial") static final class MapReduceEntriesToIntTask<K,V>
6698 >        extends Traverser<K,V,Integer> {
6699 >        final ObjectToInt<Map.Entry<K,V>> transformer;
6700 >        final IntByIntToInt reducer;
6701 >        final int basis;
6702 >        int result;
6703 >        MapReduceEntriesToIntTask<K,V> rights, nextRight;
6704 >        MapReduceEntriesToIntTask
6705 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6706 >             MapReduceEntriesToIntTask<K,V> nextRight,
6707 >             ObjectToInt<Map.Entry<K,V>> transformer,
6708 >             int basis,
6709 >             IntByIntToInt reducer) {
6710 >            super(m, p, b); this.nextRight = nextRight;
6711 >            this.transformer = transformer;
6712 >            this.basis = basis; this.reducer = reducer;
6713 >        }
6714 >        public final Integer getRawResult() { return result; }
6715 >        @SuppressWarnings("unchecked") public final void compute() {
6716 >            final ObjectToInt<Map.Entry<K,V>> transformer;
6717 >            final IntByIntToInt reducer;
6718 >            if ((transformer = this.transformer) != null &&
6719 >                (reducer = this.reducer) != null) {
6720 >                int r = this.basis;
6721 >                for (int b; (b = preSplit()) > 0;)
6722 >                    (rights = new MapReduceEntriesToIntTask<K,V>
6723 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6724 >                V v;
6725 >                while ((v = advance()) != null)
6726 >                    r = reducer.apply(r, transformer.apply(entryFor((K)nextKey,
6727 >                                                                    v)));
6728 >                result = r;
6729 >                CountedCompleter<?> c;
6730 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6731 >                    MapReduceEntriesToIntTask<K,V>
6732 >                        t = (MapReduceEntriesToIntTask<K,V>)c,
6733 >                        s = t.rights;
6734 >                    while (s != null) {
6735 >                        t.result = reducer.apply(t.result, s.result);
6736 >                        s = t.rights = s.nextRight;
6737 >                    }
6738 >                }
6739 >            }
6740 >        }
6741 >    }
6742 >
6743 >    @SuppressWarnings("serial") static final class MapReduceMappingsToIntTask<K,V>
6744 >        extends Traverser<K,V,Integer> {
6745 >        final ObjectByObjectToInt<? super K, ? super V> transformer;
6746 >        final IntByIntToInt reducer;
6747 >        final int basis;
6748 >        int result;
6749 >        MapReduceMappingsToIntTask<K,V> rights, nextRight;
6750 >        MapReduceMappingsToIntTask
6751 >            (ConcurrentHashMapV8<K,V> m, Traverser<K,V,?> p, int b,
6752 >             MapReduceMappingsToIntTask<K,V> nextRight,
6753 >             ObjectByObjectToInt<? super K, ? super V> transformer,
6754 >             int basis,
6755 >             IntByIntToInt reducer) {
6756 >            super(m, p, b); this.nextRight = nextRight;
6757 >            this.transformer = transformer;
6758 >            this.basis = basis; this.reducer = reducer;
6759 >        }
6760 >        public final Integer getRawResult() { return result; }
6761 >        @SuppressWarnings("unchecked") public final void compute() {
6762 >            final ObjectByObjectToInt<? super K, ? super V> transformer;
6763 >            final IntByIntToInt reducer;
6764 >            if ((transformer = this.transformer) != null &&
6765 >                (reducer = this.reducer) != null) {
6766 >                int r = this.basis;
6767 >                for (int b; (b = preSplit()) > 0;)
6768 >                    (rights = new MapReduceMappingsToIntTask<K,V>
6769 >                     (map, this, b, rights, transformer, r, reducer)).fork();
6770 >                V v;
6771 >                while ((v = advance()) != null)
6772 >                    r = reducer.apply(r, transformer.apply((K)nextKey, v));
6773 >                result = r;
6774 >                CountedCompleter<?> c;
6775 >                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6776 >                    MapReduceMappingsToIntTask<K,V>
6777 >                        t = (MapReduceMappingsToIntTask<K,V>)c,
6778 >                        s = t.rights;
6779 >                    while (s != null) {
6780 >                        t.result = reducer.apply(t.result, s.result);
6781 >                        s = t.rights = s.nextRight;
6782 >                    }
6783 >                }
6784 >            }
6785          }
6786      }
6787  
6788      // Unsafe mechanics
6789 <    private static final sun.misc.Unsafe UNSAFE;
6790 <    private static final long counterOffset;
6791 <    private static final long resizingOffset;
6789 >    private static final sun.misc.Unsafe U;
6790 >    private static final long SIZECTL;
6791 >    private static final long TRANSFERINDEX;
6792 >    private static final long TRANSFERORIGIN;
6793 >    private static final long BASECOUNT;
6794 >    private static final long COUNTERBUSY;
6795 >    private static final long CELLVALUE;
6796      private static final long ABASE;
6797      private static final int ASHIFT;
6798  
6799      static {
1591        int ss;
6800          try {
6801 <            UNSAFE = getUnsafe();
6801 >            U = getUnsafe();
6802              Class<?> k = ConcurrentHashMapV8.class;
6803 <            counterOffset = UNSAFE.objectFieldOffset
6804 <                (k.getDeclaredField("counter"));
6805 <            resizingOffset = UNSAFE.objectFieldOffset
6806 <                (k.getDeclaredField("resizing"));
6807 <            Class<?> sc = Node[].class;
6808 <            ABASE = UNSAFE.arrayBaseOffset(sc);
6809 <            ss = UNSAFE.arrayIndexScale(sc);
6803 >            SIZECTL = U.objectFieldOffset
6804 >                (k.getDeclaredField("sizeCtl"));
6805 >            TRANSFERINDEX = U.objectFieldOffset
6806 >                (k.getDeclaredField("transferIndex"));
6807 >            TRANSFERORIGIN = U.objectFieldOffset
6808 >                (k.getDeclaredField("transferOrigin"));
6809 >            BASECOUNT = U.objectFieldOffset
6810 >                (k.getDeclaredField("baseCount"));
6811 >            COUNTERBUSY = U.objectFieldOffset
6812 >                (k.getDeclaredField("counterBusy"));
6813 >            Class<?> ck = CounterCell.class;
6814 >            CELLVALUE = U.objectFieldOffset
6815 >                (ck.getDeclaredField("value"));
6816 >            Class<?> ak = Node[].class;
6817 >            ABASE = U.arrayBaseOffset(ak);
6818 >            int scale = U.arrayIndexScale(ak);
6819 >            if ((scale & (scale - 1)) != 0)
6820 >                throw new Error("data type scale not a power of two");
6821 >            ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6822          } catch (Exception e) {
6823              throw new Error(e);
6824          }
1605        if ((ss & (ss-1)) != 0)
1606            throw new Error("data type scale not a power of two");
1607        ASHIFT = 31 - Integer.numberOfLeadingZeros(ss);
6825      }
6826  
6827      /**
# Line 1617 | Line 6834 | public class ConcurrentHashMapV8<K, V>
6834      private static sun.misc.Unsafe getUnsafe() {
6835          try {
6836              return sun.misc.Unsafe.getUnsafe();
6837 <        } catch (SecurityException se) {
6838 <            try {
6839 <                return java.security.AccessController.doPrivileged
6840 <                    (new java.security
6841 <                     .PrivilegedExceptionAction<sun.misc.Unsafe>() {
6842 <                        public sun.misc.Unsafe run() throws Exception {
6843 <                            java.lang.reflect.Field f = sun.misc
6844 <                                .Unsafe.class.getDeclaredField("theUnsafe");
6845 <                            f.setAccessible(true);
6846 <                            return (sun.misc.Unsafe) f.get(null);
6847 <                        }});
6848 <            } catch (java.security.PrivilegedActionException e) {
6849 <                throw new RuntimeException("Could not initialize intrinsics",
6850 <                                           e.getCause());
6851 <            }
6837 >        } catch (SecurityException tryReflectionInstead) {}
6838 >        try {
6839 >            return java.security.AccessController.doPrivileged
6840 >            (new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
6841 >                public sun.misc.Unsafe run() throws Exception {
6842 >                    Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
6843 >                    for (java.lang.reflect.Field f : k.getDeclaredFields()) {
6844 >                        f.setAccessible(true);
6845 >                        Object x = f.get(null);
6846 >                        if (k.isInstance(x))
6847 >                            return k.cast(x);
6848 >                    }
6849 >                    throw new NoSuchFieldError("the Unsafe");
6850 >                }});
6851 >        } catch (java.security.PrivilegedActionException e) {
6852 >            throw new RuntimeException("Could not initialize intrinsics",
6853 >                                       e.getCause());
6854          }
6855      }
1637
6856   }

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