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Revision 1.24 by dl, Fri Oct 10 23:51:28 2003 UTC vs.
Revision 1.202 by jsr166, Thu Apr 11 17:50:12 2013 UTC

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1   /*
2   * Written by Doug Lea with assistance from members of JCP JSR-166
3 < * Expert Group and released to the public domain. Use, modify, and
4 < * redistribute this code in any way without acknowledgement.
3 > * Expert Group and released to the public domain, as explained at
4 > * http://creativecommons.org/publicdomain/zero/1.0/
5   */
6  
7   package java.util.concurrent;
8 < import java.util.concurrent.locks.*;
9 < import java.util.*;
8 > import java.util.concurrent.ForkJoinPool;
9 > import java.util.concurrent.CountedCompleter;
10 > import java.util.Spliterator;
11 > import java.util.stream.Stream;
12 > import java.util.stream.Streams;
13 > import java.util.function.*;
14 > import java.util.function.Consumer;
15 > import java.util.function.Function;
16 > import java.util.function.BiFunction;
17 >
18 > import java.util.Comparator;
19 > import java.util.Arrays;
20 > import java.util.Map;
21 > import java.util.Set;
22 > import java.util.Collection;
23 > import java.util.AbstractMap;
24 > import java.util.AbstractSet;
25 > import java.util.AbstractCollection;
26 > import java.util.Hashtable;
27 > import java.util.HashMap;
28 > import java.util.Iterator;
29 > import java.util.Enumeration;
30 > import java.util.ConcurrentModificationException;
31 > import java.util.NoSuchElementException;
32 > import java.util.concurrent.ConcurrentMap;
33 > import java.util.concurrent.locks.AbstractQueuedSynchronizer;
34 > import java.util.concurrent.atomic.AtomicInteger;
35 > import java.util.concurrent.atomic.AtomicReference;
36   import java.io.Serializable;
37 < import java.io.IOException;
38 < import java.io.ObjectInputStream;
13 < import java.io.ObjectOutputStream;
37 > import java.lang.reflect.Type;
38 > import java.lang.reflect.ParameterizedType;
39  
40   /**
41   * A hash table supporting full concurrency of retrievals and
42 < * adjustable expected concurrency for updates. This class obeys the
42 > * high expected concurrency for updates. This class obeys the
43   * same functional specification as {@link java.util.Hashtable}, and
44   * includes versions of methods corresponding to each method of
45 < * <tt>Hashtable</tt> . However, even though all operations are
45 > * {@code Hashtable}. However, even though all operations are
46   * thread-safe, retrieval operations do <em>not</em> entail locking,
47   * and there is <em>not</em> any support for locking the entire table
48   * in a way that prevents all access.  This class is fully
49 < * interoperable with <tt>Hashtable</tt> in programs that rely on its
49 > * interoperable with {@code Hashtable} in programs that rely on its
50   * thread safety but not on its synchronization details.
51   *
52 < * <p> Retrieval operations (including <tt>get</tt>) ordinarily
53 < * overlap with update operations (including <tt>put</tt> and
54 < * <tt>remove</tt>). Retrievals reflect the results of the most
52 > * <p>Retrieval operations (including {@code get}) generally do not
53 > * block, so may overlap with update operations (including {@code put}
54 > * and {@code remove}). Retrievals reflect the results of the most
55   * recently <em>completed</em> update operations holding upon their
56 < * onset.  For aggregate operations such as <tt>putAll</tt> and
57 < * <tt>clear</tt>, concurrent retrievals may reflect insertion or
58 < * removal of only some entries.  Similarly, Iterators and
59 < * Enumerations return elements reflecting the state of the hash table
60 < * at some point at or since the creation of the iterator/enumeration.
61 < * They do <em>not</em> throw <tt>ConcurrentModificationException</tt>.
62 < * However, Iterators are designed to be used by only one thread at a
63 < * time.
64 < *
65 < * <p> The allowed concurrency among update operations is guided by
66 < * the optional <tt>concurrencyLevel</tt> constructor argument
67 < * (default 16), which is used as a hint for internal sizing.  The
68 < * table is internally partitioned to try to permit the indicated
69 < * number of concurrent updates without contention. Because placement
70 < * in hash tables is essentially random, the actual concurrency will
71 < * vary.  Ideally, you should choose a value to accommodate as many
72 < * threads as will ever concurrently access the table. Using a
73 < * significantly higher value than you need can waste space and time,
74 < * and a significantly lower value can lead to thread contention. But
75 < * overestimates and underestimates within an order of magnitude do
76 < * not usually have much noticeable impact.
77 < *
78 < * <p>This class implements all of the <em>optional</em> methods
79 < * of the {@link Map} and {@link Iterator} interfaces.
80 < *
81 < * <p> Like {@link java.util.Hashtable} but unlike {@link
82 < * java.util.HashMap}, this class does NOT allow <tt>null</tt> to be
83 < * used as a key or value.
56 > * onset. (More formally, an update operation for a given key bears a
57 > * <em>happens-before</em> relation with any (non-null) retrieval for
58 > * that key reporting the updated value.)  For aggregate operations
59 > * such as {@code putAll} and {@code clear}, concurrent retrievals may
60 > * reflect insertion or removal of only some entries.  Similarly,
61 > * Iterators and Enumerations return elements reflecting the state of
62 > * the hash table at some point at or since the creation of the
63 > * iterator/enumeration.  They do <em>not</em> throw {@link
64 > * ConcurrentModificationException}.  However, iterators are designed
65 > * to be used by only one thread at a time.  Bear in mind that the
66 > * results of aggregate status methods including {@code size}, {@code
67 > * isEmpty}, and {@code containsValue} are typically useful only when
68 > * a map is not undergoing concurrent updates in other threads.
69 > * Otherwise the results of these methods reflect transient states
70 > * that may be adequate for monitoring or estimation purposes, but not
71 > * for program control.
72 > *
73 > * <p>The table is dynamically expanded when there are too many
74 > * collisions (i.e., keys that have distinct hash codes but fall into
75 > * the same slot modulo the table size), with the expected average
76 > * effect of maintaining roughly two bins per mapping (corresponding
77 > * to a 0.75 load factor threshold for resizing). There may be much
78 > * variance around this average as mappings are added and removed, but
79 > * overall, this maintains a commonly accepted time/space tradeoff for
80 > * hash tables.  However, resizing this or any other kind of hash
81 > * table may be a relatively slow operation. When possible, it is a
82 > * good idea to provide a size estimate as an optional {@code
83 > * initialCapacity} constructor argument. An additional optional
84 > * {@code loadFactor} constructor argument provides a further means of
85 > * customizing initial table capacity by specifying the table density
86 > * to be used in calculating the amount of space to allocate for the
87 > * given number of elements.  Also, for compatibility with previous
88 > * versions of this class, constructors may optionally specify an
89 > * expected {@code concurrencyLevel} as an additional hint for
90 > * internal sizing.  Note that using many keys with exactly the same
91 > * {@code hashCode()} is a sure way to slow down performance of any
92 > * hash table.
93 > *
94 > * <p>A {@link Set} projection of a ConcurrentHashMap may be created
95 > * (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed
96 > * (using {@link #keySet(Object)} when only keys are of interest, and the
97 > * mapped values are (perhaps transiently) not used or all take the
98 > * same mapping value.
99 > *
100 > * <p>A ConcurrentHashMap can be used as scalable frequency map (a
101 > * form of histogram or multiset) by using {@link
102 > * java.util.concurrent.atomic.LongAdder} values and initializing via
103 > * {@link #computeIfAbsent computeIfAbsent}. For example, to add a count
104 > * to a {@code ConcurrentHashMap<String,LongAdder> freqs}, you can use
105 > * {@code freqs.computeIfAbsent(k -> new LongAdder()).increment();}
106 > *
107 > * <p>This class and its views and iterators implement all of the
108 > * <em>optional</em> methods of the {@link Map} and {@link Iterator}
109 > * interfaces.
110 > *
111 > * <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
112 > * does <em>not</em> allow {@code null} to be used as a key or value.
113 > *
114 > * <p>ConcurrentHashMaps support sequential and parallel operations
115 > * bulk operations. (Parallel forms use the {@link
116 > * ForkJoinPool#commonPool()}). Tasks that may be used in other
117 > * contexts are available in class {@link ForkJoinTasks}. These
118 > * operations are designed to be safely, and often sensibly, applied
119 > * even with maps that are being concurrently updated by other
120 > * threads; for example, when computing a snapshot summary of the
121 > * values in a shared registry.  There are three kinds of operation,
122 > * each with four forms, accepting functions with Keys, Values,
123 > * Entries, and (Key, Value) arguments and/or return values. Because
124 > * the elements of a ConcurrentHashMap are not ordered in any
125 > * particular way, and may be processed in different orders in
126 > * different parallel executions, the correctness of supplied
127 > * functions should not depend on any ordering, or on any other
128 > * objects or values that may transiently change while computation is
129 > * in progress; and except for forEach actions, should ideally be
130 > * side-effect-free.
131 > *
132 > * <ul>
133 > * <li> forEach: Perform a given action on each element.
134 > * A variant form applies a given transformation on each element
135 > * before performing the action.</li>
136 > *
137 > * <li> search: Return the first available non-null result of
138 > * applying a given function on each element; skipping further
139 > * search when a result is found.</li>
140 > *
141 > * <li> reduce: Accumulate each element.  The supplied reduction
142 > * function cannot rely on ordering (more formally, it should be
143 > * both associative and commutative).  There are five variants:
144 > *
145 > * <ul>
146 > *
147 > * <li> Plain reductions. (There is not a form of this method for
148 > * (key, value) function arguments since there is no corresponding
149 > * return type.)</li>
150 > *
151 > * <li> Mapped reductions that accumulate the results of a given
152 > * function applied to each element.</li>
153 > *
154 > * <li> Reductions to scalar doubles, longs, and ints, using a
155 > * given basis value.</li>
156 > *
157 > * </ul>
158 > * </li>
159 > * </ul>
160 > *
161 > * <p>The concurrency properties of bulk operations follow
162 > * from those of ConcurrentHashMap: Any non-null result returned
163 > * from {@code get(key)} and related access methods bears a
164 > * happens-before relation with the associated insertion or
165 > * update.  The result of any bulk operation reflects the
166 > * composition of these per-element relations (but is not
167 > * necessarily atomic with respect to the map as a whole unless it
168 > * is somehow known to be quiescent).  Conversely, because keys
169 > * and values in the map are never null, null serves as a reliable
170 > * atomic indicator of the current lack of any result.  To
171 > * maintain this property, null serves as an implicit basis for
172 > * all non-scalar reduction operations. For the double, long, and
173 > * int versions, the basis should be one that, when combined with
174 > * any other value, returns that other value (more formally, it
175 > * should be the identity element for the reduction). Most common
176 > * reductions have these properties; for example, computing a sum
177 > * with basis 0 or a minimum with basis MAX_VALUE.
178 > *
179 > * <p>Search and transformation functions provided as arguments
180 > * should similarly return null to indicate the lack of any result
181 > * (in which case it is not used). In the case of mapped
182 > * reductions, this also enables transformations to serve as
183 > * filters, returning null (or, in the case of primitive
184 > * specializations, the identity basis) if the element should not
185 > * be combined. You can create compound transformations and
186 > * filterings by composing them yourself under this "null means
187 > * there is nothing there now" rule before using them in search or
188 > * reduce operations.
189 > *
190 > * <p>Methods accepting and/or returning Entry arguments maintain
191 > * key-value associations. They may be useful for example when
192 > * finding the key for the greatest value. Note that "plain" Entry
193 > * arguments can be supplied using {@code new
194 > * AbstractMap.SimpleEntry(k,v)}.
195 > *
196 > * <p>Bulk operations may complete abruptly, throwing an
197 > * exception encountered in the application of a supplied
198 > * function. Bear in mind when handling such exceptions that other
199 > * concurrently executing functions could also have thrown
200 > * exceptions, or would have done so if the first exception had
201 > * not occurred.
202 > *
203 > * <p>Speedups for parallel compared to sequential forms are common
204 > * but not guaranteed.  Parallel operations involving brief functions
205 > * on small maps may execute more slowly than sequential forms if the
206 > * underlying work to parallelize the computation is more expensive
207 > * than the computation itself.  Similarly, parallelization may not
208 > * lead to much actual parallelism if all processors are busy
209 > * performing unrelated tasks.
210 > *
211 > * <p>All arguments to all task methods must be non-null.
212 > *
213 > * <p>This class is a member of the
214 > * <a href="{@docRoot}/../technotes/guides/collections/index.html">
215 > * Java Collections Framework</a>.
216   *
217   * @since 1.5
218   * @author Doug Lea
219 + * @param <K> the type of keys maintained by this map
220 + * @param <V> the type of mapped values
221   */
222 < public class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
223 <        implements ConcurrentMap<K, V>, Cloneable, Serializable {
222 > public class ConcurrentHashMap<K,V>
223 >    implements ConcurrentMap<K,V>, Serializable {
224      private static final long serialVersionUID = 7249069246763182397L;
225  
226      /*
227 <     * The basic strategy is to subdivide the table among Segments,
228 <     * each of which itself is a concurrently readable hash table.
227 >     * Overview:
228 >     *
229 >     * The primary design goal of this hash table is to maintain
230 >     * concurrent readability (typically method get(), but also
231 >     * iterators and related methods) while minimizing update
232 >     * contention. Secondary goals are to keep space consumption about
233 >     * the same or better than java.util.HashMap, and to support high
234 >     * initial insertion rates on an empty table by many threads.
235 >     *
236 >     * Each key-value mapping is held in a Node.  Because Node key
237 >     * fields can contain special values, they are defined using plain
238 >     * Object types (not type "K"). This leads to a lot of explicit
239 >     * casting (and many explicit warning suppressions to tell
240 >     * compilers not to complain about it). It also allows some of the
241 >     * public methods to be factored into a smaller number of internal
242 >     * methods (although sadly not so for the five variants of
243 >     * put-related operations). The validation-based approach
244 >     * explained below leads to a lot of code sprawl because
245 >     * retry-control precludes factoring into smaller methods.
246 >     *
247 >     * The table is lazily initialized to a power-of-two size upon the
248 >     * first insertion.  Each bin in the table normally contains a
249 >     * list of Nodes (most often, the list has only zero or one Node).
250 >     * Table accesses require volatile/atomic reads, writes, and
251 >     * CASes.  Because there is no other way to arrange this without
252 >     * adding further indirections, we use intrinsics
253 >     * (sun.misc.Unsafe) operations.  The lists of nodes within bins
254 >     * are always accurately traversable under volatile reads, so long
255 >     * as lookups check hash code and non-nullness of value before
256 >     * checking key equality.
257 >     *
258 >     * We use the top (sign) bit of Node hash fields for control
259 >     * purposes -- it is available anyway because of addressing
260 >     * constraints.  Nodes with negative hash fields are forwarding
261 >     * nodes to either TreeBins or resized tables.  The lower 31 bits
262 >     * of each normal Node's hash field contain a transformation of
263 >     * the key's hash code.
264 >     *
265 >     * Insertion (via put or its variants) of the first node in an
266 >     * empty bin is performed by just CASing it to the bin.  This is
267 >     * by far the most common case for put operations under most
268 >     * key/hash distributions.  Other update operations (insert,
269 >     * delete, and replace) require locks.  We do not want to waste
270 >     * the space required to associate a distinct lock object with
271 >     * each bin, so instead use the first node of a bin list itself as
272 >     * a lock. Locking support for these locks relies on builtin
273 >     * "synchronized" monitors.
274 >     *
275 >     * Using the first node of a list as a lock does not by itself
276 >     * suffice though: When a node is locked, any update must first
277 >     * validate that it is still the first node after locking it, and
278 >     * retry if not. Because new nodes are always appended to lists,
279 >     * once a node is first in a bin, it remains first until deleted
280 >     * or the bin becomes invalidated (upon resizing).  However,
281 >     * operations that only conditionally update may inspect nodes
282 >     * until the point of update. This is a converse of sorts to the
283 >     * lazy locking technique described by Herlihy & Shavit.
284 >     *
285 >     * The main disadvantage of per-bin locks is that other update
286 >     * operations on other nodes in a bin list protected by the same
287 >     * lock can stall, for example when user equals() or mapping
288 >     * functions take a long time.  However, statistically, under
289 >     * random hash codes, this is not a common problem.  Ideally, the
290 >     * frequency of nodes in bins follows a Poisson distribution
291 >     * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
292 >     * parameter of about 0.5 on average, given the resizing threshold
293 >     * of 0.75, although with a large variance because of resizing
294 >     * granularity. Ignoring variance, the expected occurrences of
295 >     * list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
296 >     * first values are:
297 >     *
298 >     * 0:    0.60653066
299 >     * 1:    0.30326533
300 >     * 2:    0.07581633
301 >     * 3:    0.01263606
302 >     * 4:    0.00157952
303 >     * 5:    0.00015795
304 >     * 6:    0.00001316
305 >     * 7:    0.00000094
306 >     * 8:    0.00000006
307 >     * more: less than 1 in ten million
308 >     *
309 >     * Lock contention probability for two threads accessing distinct
310 >     * elements is roughly 1 / (8 * #elements) under random hashes.
311 >     *
312 >     * Actual hash code distributions encountered in practice
313 >     * sometimes deviate significantly from uniform randomness.  This
314 >     * includes the case when N > (1<<30), so some keys MUST collide.
315 >     * Similarly for dumb or hostile usages in which multiple keys are
316 >     * designed to have identical hash codes. Also, although we guard
317 >     * against the worst effects of this (see method spread), sets of
318 >     * hashes may differ only in bits that do not impact their bin
319 >     * index for a given power-of-two mask.  So we use a secondary
320 >     * strategy that applies when the number of nodes in a bin exceeds
321 >     * a threshold, and at least one of the keys implements
322 >     * Comparable.  These TreeBins use a balanced tree to hold nodes
323 >     * (a specialized form of red-black trees), bounding search time
324 >     * to O(log N).  Each search step in a TreeBin is around twice as
325 >     * slow as in a regular list, but given that N cannot exceed
326 >     * (1<<64) (before running out of addresses) this bounds search
327 >     * steps, lock hold times, etc, to reasonable constants (roughly
328 >     * 100 nodes inspected per operation worst case) so long as keys
329 >     * are Comparable (which is very common -- String, Long, etc).
330 >     * TreeBin nodes (TreeNodes) also maintain the same "next"
331 >     * traversal pointers as regular nodes, so can be traversed in
332 >     * iterators in the same way.
333 >     *
334 >     * The table is resized when occupancy exceeds a percentage
335 >     * threshold (nominally, 0.75, but see below).  Any thread
336 >     * noticing an overfull bin may assist in resizing after the
337 >     * initiating thread allocates and sets up the replacement
338 >     * array. However, rather than stalling, these other threads may
339 >     * proceed with insertions etc.  The use of TreeBins shields us
340 >     * from the worst case effects of overfilling while resizes are in
341 >     * progress.  Resizing proceeds by transferring bins, one by one,
342 >     * from the table to the next table. To enable concurrency, the
343 >     * next table must be (incrementally) prefilled with place-holders
344 >     * serving as reverse forwarders to the old table.  Because we are
345 >     * using power-of-two expansion, the elements from each bin must
346 >     * either stay at same index, or move with a power of two
347 >     * offset. We eliminate unnecessary node creation by catching
348 >     * cases where old nodes can be reused because their next fields
349 >     * won't change.  On average, only about one-sixth of them need
350 >     * cloning when a table doubles. The nodes they replace will be
351 >     * garbage collectable as soon as they are no longer referenced by
352 >     * any reader thread that may be in the midst of concurrently
353 >     * traversing table.  Upon transfer, the old table bin contains
354 >     * only a special forwarding node (with hash field "MOVED") that
355 >     * contains the next table as its key. On encountering a
356 >     * forwarding node, access and update operations restart, using
357 >     * the new table.
358 >     *
359 >     * Each bin transfer requires its bin lock, which can stall
360 >     * waiting for locks while resizing. However, because other
361 >     * threads can join in and help resize rather than contend for
362 >     * locks, average aggregate waits become shorter as resizing
363 >     * progresses.  The transfer operation must also ensure that all
364 >     * accessible bins in both the old and new table are usable by any
365 >     * traversal.  This is arranged by proceeding from the last bin
366 >     * (table.length - 1) up towards the first.  Upon seeing a
367 >     * forwarding node, traversals (see class Traverser) arrange to
368 >     * move to the new table without revisiting nodes.  However, to
369 >     * ensure that no intervening nodes are skipped, bin splitting can
370 >     * only begin after the associated reverse-forwarders are in
371 >     * place.
372 >     *
373 >     * The traversal scheme also applies to partial traversals of
374 >     * ranges of bins (via an alternate Traverser constructor)
375 >     * to support partitioned aggregate operations.  Also, read-only
376 >     * operations give up if ever forwarded to a null table, which
377 >     * provides support for shutdown-style clearing, which is also not
378 >     * currently implemented.
379 >     *
380 >     * Lazy table initialization minimizes footprint until first use,
381 >     * and also avoids resizings when the first operation is from a
382 >     * putAll, constructor with map argument, or deserialization.
383 >     * These cases attempt to override the initial capacity settings,
384 >     * but harmlessly fail to take effect in cases of races.
385 >     *
386 >     * The element count is maintained using a specialization of
387 >     * LongAdder. We need to incorporate a specialization rather than
388 >     * just use a LongAdder in order to access implicit
389 >     * contention-sensing that leads to creation of multiple
390 >     * Cells.  The counter mechanics avoid contention on
391 >     * updates but can encounter cache thrashing if read too
392 >     * frequently during concurrent access. To avoid reading so often,
393 >     * resizing under contention is attempted only upon adding to a
394 >     * bin already holding two or more nodes. Under uniform hash
395 >     * distributions, the probability of this occurring at threshold
396 >     * is around 13%, meaning that only about 1 in 8 puts check
397 >     * threshold (and after resizing, many fewer do so). The bulk
398 >     * putAll operation further reduces contention by only committing
399 >     * count updates upon these size checks.
400 >     *
401 >     * Maintaining API and serialization compatibility with previous
402 >     * versions of this class introduces several oddities. Mainly: We
403 >     * leave untouched but unused constructor arguments refering to
404 >     * concurrencyLevel. We accept a loadFactor constructor argument,
405 >     * but apply it only to initial table capacity (which is the only
406 >     * time that we can guarantee to honor it.) We also declare an
407 >     * unused "Segment" class that is instantiated in minimal form
408 >     * only when serializing.
409       */
410  
411      /* ---------------- Constants -------------- */
412  
413      /**
414 <     * The default initial number of table slots for this table.
415 <     * Used when not otherwise specified in constructor.
414 >     * The largest possible table capacity.  This value must be
415 >     * exactly 1<<30 to stay within Java array allocation and indexing
416 >     * bounds for power of two table sizes, and is further required
417 >     * because the top two bits of 32bit hash fields are used for
418 >     * control purposes.
419       */
420 <    private static int DEFAULT_INITIAL_CAPACITY = 16;
420 >    private static final int MAXIMUM_CAPACITY = 1 << 30;
421  
422      /**
423 <     * The maximum capacity, used if a higher value is implicitly
424 <     * specified by either of the constructors with arguments.  MUST
83 <     * be a power of two <= 1<<30 to ensure that entries are indexible
84 <     * using ints.
423 >     * The default initial table capacity.  Must be a power of 2
424 >     * (i.e., at least 1) and at most MAXIMUM_CAPACITY.
425       */
426 <    static final int MAXIMUM_CAPACITY = 1 << 30;
426 >    private static final int DEFAULT_CAPACITY = 16;
427  
428      /**
429 <     * The default load factor for this table.  Used when not
430 <     * otherwise specified in constructor.
429 >     * The largest possible (non-power of two) array size.
430 >     * Needed by toArray and related methods.
431       */
432 <    static final float DEFAULT_LOAD_FACTOR = 0.75f;
432 >    static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
433  
434      /**
435 <     * The default number of concurrency control segments.
436 <     **/
437 <    private static final int DEFAULT_SEGMENTS = 16;
435 >     * The default concurrency level for this table. Unused but
436 >     * defined for compatibility with previous versions of this class.
437 >     */
438 >    private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
439 >
440 >    /**
441 >     * The load factor for this table. Overrides of this value in
442 >     * constructors affect only the initial table capacity.  The
443 >     * actual floating point value isn't normally used -- it is
444 >     * simpler to use expressions such as {@code n - (n >>> 2)} for
445 >     * the associated resizing threshold.
446 >     */
447 >    private static final float LOAD_FACTOR = 0.75f;
448 >
449 >    /**
450 >     * The bin count threshold for using a tree rather than list for a
451 >     * bin.  The value reflects the approximate break-even point for
452 >     * using tree-based operations.
453 >     */
454 >    private static final int TREE_THRESHOLD = 16;
455  
456      /**
457 <     * The maximum number of segments to allow; used to bound ctor arguments.
457 >     * Minimum number of rebinnings per transfer step. Ranges are
458 >     * subdivided to allow multiple resizer threads.  This value
459 >     * serves as a lower bound to avoid resizers encountering
460 >     * excessive memory contention.  The value should be at least
461 >     * DEFAULT_CAPACITY.
462 >     */
463 >    private static final int MIN_TRANSFER_STRIDE = 16;
464 >
465 >    /*
466 >     * Encodings for Node hash fields. See above for explanation.
467       */
468 <    private static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
468 >    static final int MOVED     = 0x80000000; // hash field for forwarding nodes
469 >    static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
470 >
471 >    /** Number of CPUS, to place bounds on some sizings */
472 >    static final int NCPU = Runtime.getRuntime().availableProcessors();
473 >
474 >    /* ---------------- Counters -------------- */
475 >
476 >    // Adapted from LongAdder and Striped64.
477 >    // See their internal docs for explanation.
478 >
479 >    // A padded cell for distributing counts
480 >    static final class Cell {
481 >        volatile long p0, p1, p2, p3, p4, p5, p6;
482 >        volatile long value;
483 >        volatile long q0, q1, q2, q3, q4, q5, q6;
484 >        Cell(long x) { value = x; }
485 >    }
486  
487      /* ---------------- Fields -------------- */
488  
489      /**
490 <     * Mask value for indexing into segments. The upper bits of a
491 <     * key's hash code are used to choose the segment.
492 <     **/
493 <    private final int segmentMask;
490 >     * The array of bins. Lazily initialized upon first insertion.
491 >     * Size is always a power of two. Accessed directly by iterators.
492 >     */
493 >    transient volatile Node<V>[] table;
494  
495      /**
496 <     * Shift value for indexing within segments.
497 <     **/
498 <    private final int segmentShift;
496 >     * The next table to use; non-null only while resizing.
497 >     */
498 >    private transient volatile Node<V>[] nextTable;
499  
500      /**
501 <     * The segments, each of which is a specialized hash table
501 >     * Base counter value, used mainly when there is no contention,
502 >     * but also as a fallback during table initialization
503 >     * races. Updated via CAS.
504       */
505 <    private final Segment[] segments;
505 >    private transient volatile long baseCount;
506  
507 <    private transient Set<K> keySet;
508 <    private transient Set<Map.Entry<K,V>> entrySet;
509 <    private transient Collection<V> values;
507 >    /**
508 >     * Table initialization and resizing control.  When negative, the
509 >     * table is being initialized or resized: -1 for initialization,
510 >     * else -(1 + the number of active resizing threads).  Otherwise,
511 >     * when table is null, holds the initial table size to use upon
512 >     * creation, or 0 for default. After initialization, holds the
513 >     * next element count value upon which to resize the table.
514 >     */
515 >    private transient volatile int sizeCtl;
516  
517 <    /* ---------------- Small Utilities -------------- */
517 >    /**
518 >     * The next table index (plus one) to split while resizing.
519 >     */
520 >    private transient volatile int transferIndex;
521  
522      /**
523 <     * Return a hash code for non-null Object x.
130 <     * Uses the same hash code spreader as most other j.u hash tables.
131 <     * @param x the object serving as a key
132 <     * @return the hash code
523 >     * The least available table index to split while resizing.
524       */
525 <    private static int hash(Object x) {
526 <        int h = x.hashCode();
527 <        h += ~(h << 9);
528 <        h ^=  (h >>> 14);
529 <        h +=  (h << 4);
530 <        h ^=  (h >>> 10);
531 <        return h;
525 >    private transient volatile int transferOrigin;
526 >
527 >    /**
528 >     * Spinlock (locked via CAS) used when resizing and/or creating Cells.
529 >     */
530 >    private transient volatile int cellsBusy;
531 >
532 >    /**
533 >     * Table of counter cells. When non-null, size is a power of 2.
534 >     */
535 >    private transient volatile Cell[] counterCells;
536 >
537 >    // views
538 >    private transient KeySetView<K,V> keySet;
539 >    private transient ValuesView<K,V> values;
540 >    private transient EntrySetView<K,V> entrySet;
541 >
542 >    /** For serialization compatibility. Null unless serialized; see below */
543 >    private Segment<K,V>[] segments;
544 >
545 >    /* ---------------- Table element access -------------- */
546 >
547 >    /*
548 >     * Volatile access methods are used for table elements as well as
549 >     * elements of in-progress next table while resizing.  Uses are
550 >     * null checked by callers, and implicitly bounds-checked, relying
551 >     * on the invariants that tab arrays have non-zero size, and all
552 >     * indices are masked with (tab.length - 1) which is never
553 >     * negative and always less than length. Note that, to be correct
554 >     * wrt arbitrary concurrency errors by users, bounds checks must
555 >     * operate on local variables, which accounts for some odd-looking
556 >     * inline assignments below.
557 >     */
558 >
559 >    @SuppressWarnings("unchecked") static final <V> Node<V> tabAt
560 >        (Node<V>[] tab, int i) { // used by Traverser
561 >        return (Node<V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
562      }
563  
564 +    private static final <V> boolean casTabAt
565 +        (Node<V>[] tab, int i, Node<V> c, Node<V> v) {
566 +        return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
567 +    }
568 +
569 +    private static final <V> void setTabAt
570 +        (Node<V>[] tab, int i, Node<V> v) {
571 +        U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
572 +    }
573 +
574 +    /* ---------------- Nodes -------------- */
575 +
576      /**
577 <     * Return the segment that should be used for key with given hash
577 >     * Key-value entry. Note that this is never exported out as a
578 >     * user-visible Map.Entry (see MapEntry below). Nodes with a hash
579 >     * field of MOVED are special, and do not contain user keys or
580 >     * values.  Otherwise, keys are never null, and null val fields
581 >     * indicate that a node is in the process of being deleted or
582 >     * created. For purposes of read-only access, a key may be read
583 >     * before a val, but can only be used after checking val to be
584 >     * non-null.
585       */
586 <    private Segment<K,V> segmentFor(int hash) {
587 <        return (Segment<K,V>) segments[(hash >>> segmentShift) & segmentMask];
586 >    static class Node<V> {
587 >        final int hash;
588 >        final Object key;
589 >        volatile V val;
590 >        volatile Node<V> next;
591 >
592 >        Node(int hash, Object key, V val, Node<V> next) {
593 >            this.hash = hash;
594 >            this.key = key;
595 >            this.val = val;
596 >            this.next = next;
597 >        }
598      }
599  
600 <    /* ---------------- Inner Classes -------------- */
600 >    /* ---------------- TreeBins -------------- */
601  
602      /**
603 <     * Segments are specialized versions of hash tables.  This
604 <     * subclasses from ReentrantLock opportunistically, just to
605 <     * simplify some locking and avoid separate construction.
606 <     **/
607 <    private static final class Segment<K,V> extends ReentrantLock implements Serializable {
608 <        /*
609 <         * Segments maintain a table of entry lists that are ALWAYS
610 <         * kept in a consistent state, so can be read without locking.
611 <         * Next fields of nodes are immutable (final).  All list
612 <         * additions are performed at the front of each bin. This
613 <         * makes it easy to check changes, and also fast to traverse.
614 <         * When nodes would otherwise be changed, new nodes are
615 <         * created to replace them. This works well for hash tables
616 <         * since the bin lists tend to be short. (The average length
167 <         * is less than two for the default load factor threshold.)
168 <         *
169 <         * Read operations can thus proceed without locking, but rely
170 <         * on a memory barrier to ensure that completed write
171 <         * operations performed by other threads are
172 <         * noticed. Conveniently, the "count" field, tracking the
173 <         * number of elements, can also serve as the volatile variable
174 <         * providing proper read/write barriers. This is convenient
175 <         * because this field needs to be read in many read operations
176 <         * anyway.
177 <         *
178 <         * Implementors note. The basic rules for all this are:
179 <         *
180 <         *   - All unsynchronized read operations must first read the
181 <         *     "count" field, and should not look at table entries if
182 <         *     it is 0.
183 <         *
184 <         *   - All synchronized write operations should write to
185 <         *     the "count" field after updating. The operations must not
186 <         *     take any action that could even momentarily cause
187 <         *     a concurrent read operation to see inconsistent
188 <         *     data. This is made easier by the nature of the read
189 <         *     operations in Map. For example, no operation
190 <         *     can reveal that the table has grown but the threshold
191 <         *     has not yet been updated, so there are no atomicity
192 <         *     requirements for this with respect to reads.
193 <         *
194 <         * As a guide, all critical volatile reads and writes are marked
195 <         * in code comments.
196 <         */
603 >     * Nodes for use in TreeBins
604 >     */
605 >    static final class TreeNode<V> extends Node<V> {
606 >        TreeNode<V> parent;  // red-black tree links
607 >        TreeNode<V> left;
608 >        TreeNode<V> right;
609 >        TreeNode<V> prev;    // needed to unlink next upon deletion
610 >        boolean red;
611 >
612 >        TreeNode(int hash, Object key, V val, Node<V> next, TreeNode<V> parent) {
613 >            super(hash, key, val, next);
614 >            this.parent = parent;
615 >        }
616 >    }
617  
618 +
619 +    /**
620 +     * Returns a Class for the given object of the form "class C
621 +     * implements Comparable<C>", if one exists, else null.  See below
622 +     * for explanation.
623 +     */
624 +    static Class<?> comparableClassFor(Object x) {
625 +        Class<?> c, s, cmpc; Type[] ts, as; Type t; ParameterizedType p;
626 +        if ((c = x.getClass()) == String.class) // bypass checks
627 +            return c;
628 +        if ((cmpc = Comparable.class).isAssignableFrom(c)) {
629 +            while (cmpc.isAssignableFrom(s = c.getSuperclass()))
630 +                c = s; // find topmost comparable class
631 +            if ((ts  = c.getGenericInterfaces()) != null) {
632 +                for (int i = 0; i < ts.length; ++i) {
633 +                    if (((t = ts[i]) instanceof ParameterizedType) &&
634 +                        ((p = (ParameterizedType)t).getRawType() == cmpc) &&
635 +                        (as = p.getActualTypeArguments()) != null &&
636 +                        as.length == 1 && as[0] == c) // type arg is c
637 +                        return c;
638 +                }
639 +            }
640 +        }
641 +        return null;
642 +    }
643 +
644 +    /**
645 +     * A specialized form of red-black tree for use in bins
646 +     * whose size exceeds a threshold.
647 +     *
648 +     * TreeBins use a special form of comparison for search and
649 +     * related operations (which is the main reason we cannot use
650 +     * existing collections such as TreeMaps). TreeBins contain
651 +     * Comparable elements, but may contain others, as well as
652 +     * elements that are Comparable but not necessarily Comparable<T>
653 +     * for the same T, so we cannot invoke compareTo among them. To
654 +     * handle this, the tree is ordered primarily by hash value, then
655 +     * by Comparable.compareTo order if applicable, else by class
656 +     * names if both comparable but not to each other.  On lookup at a
657 +     * node, if elements are not comparable or compare as 0 then both
658 +     * left and right children may need to be searched in the case of
659 +     * tied hash values. (This corresponds to the full list search
660 +     * that would be necessary if all elements were non-Comparable and
661 +     * had tied hashes.)  The red-black balancing code is updated from
662 +     * pre-jdk-collections
663 +     * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
664 +     * based in turn on Cormen, Leiserson, and Rivest "Introduction to
665 +     * Algorithms" (CLR).
666 +     *
667 +     * TreeBins also maintain a separate locking discipline than
668 +     * regular bins. Because they are forwarded via special MOVED
669 +     * nodes at bin heads (which can never change once established),
670 +     * we cannot use those nodes as locks. Instead, TreeBin
671 +     * extends AbstractQueuedSynchronizer to support a simple form of
672 +     * read-write lock. For update operations and table validation,
673 +     * the exclusive form of lock behaves in the same way as bin-head
674 +     * locks. However, lookups use shared read-lock mechanics to allow
675 +     * multiple readers in the absence of writers.  Additionally,
676 +     * these lookups do not ever block: While the lock is not
677 +     * available, they proceed along the slow traversal path (via
678 +     * next-pointers) until the lock becomes available or the list is
679 +     * exhausted, whichever comes first. (These cases are not fast,
680 +     * but maximize aggregate expected throughput.)  The AQS mechanics
681 +     * for doing this are straightforward.  The lock state is held as
682 +     * AQS getState().  Read counts are negative; the write count (1)
683 +     * is positive.  There are no signalling preferences among readers
684 +     * and writers. Since we don't need to export full Lock API, we
685 +     * just override the minimal AQS methods and use them directly.
686 +     */
687 +    static final class TreeBin<V> extends AbstractQueuedSynchronizer {
688          private static final long serialVersionUID = 2249069246763182397L;
689 +        transient TreeNode<V> root;  // root of tree
690 +        transient TreeNode<V> first; // head of next-pointer list
691 +
692 +        /* AQS overrides */
693 +        public final boolean isHeldExclusively() { return getState() > 0; }
694 +        public final boolean tryAcquire(int ignore) {
695 +            if (compareAndSetState(0, 1)) {
696 +                setExclusiveOwnerThread(Thread.currentThread());
697 +                return true;
698 +            }
699 +            return false;
700 +        }
701 +        public final boolean tryRelease(int ignore) {
702 +            setExclusiveOwnerThread(null);
703 +            setState(0);
704 +            return true;
705 +        }
706 +        public final int tryAcquireShared(int ignore) {
707 +            for (int c;;) {
708 +                if ((c = getState()) > 0)
709 +                    return -1;
710 +                if (compareAndSetState(c, c -1))
711 +                    return 1;
712 +            }
713 +        }
714 +        public final boolean tryReleaseShared(int ignore) {
715 +            int c;
716 +            do {} while (!compareAndSetState(c = getState(), c + 1));
717 +            return c == -1;
718 +        }
719 +
720 +        /** From CLR */
721 +        private void rotateLeft(TreeNode<V> p) {
722 +            if (p != null) {
723 +                TreeNode<V> r = p.right, pp, rl;
724 +                if ((rl = p.right = r.left) != null)
725 +                    rl.parent = p;
726 +                if ((pp = r.parent = p.parent) == null)
727 +                    root = r;
728 +                else if (pp.left == p)
729 +                    pp.left = r;
730 +                else
731 +                    pp.right = r;
732 +                r.left = p;
733 +                p.parent = r;
734 +            }
735 +        }
736 +
737 +        /** From CLR */
738 +        private void rotateRight(TreeNode<V> p) {
739 +            if (p != null) {
740 +                TreeNode<V> l = p.left, pp, lr;
741 +                if ((lr = p.left = l.right) != null)
742 +                    lr.parent = p;
743 +                if ((pp = l.parent = p.parent) == null)
744 +                    root = l;
745 +                else if (pp.right == p)
746 +                    pp.right = l;
747 +                else
748 +                    pp.left = l;
749 +                l.right = p;
750 +                p.parent = l;
751 +            }
752 +        }
753  
754          /**
755 <         * The number of elements in this segment's region.
756 <         **/
757 <        transient volatile int count;
755 >         * Compares k and x: if k's comparable class (cc) matches x's,
756 >         * uses Comparable.compareTo. Otherwise compares on comparable
757 >         * class name if either exist, else 0.
758 >         */
759 >        @SuppressWarnings("unchecked")
760 >        static int cccompare(Class<?> cc, Object k, Object x) {
761 >            Class<?> cx = comparableClassFor(x);
762 >            return ((cc == null) ? ((cx == null) ? 0 : 1) :
763 >                    (cx == null) ? -1 :
764 >                    (cx == cc) ? ((Comparable<Object>)k).compareTo(x) :
765 >                    cc.getName().compareTo(cx.getName()));
766 >        }
767  
768          /**
769 <         * Number of updates; used for checking lack of modifications
770 <         * in bulk-read methods.
769 >         * Returns the TreeNode (or null if not found) for the given
770 >         * key.  A front-end for recursive version.
771           */
772 <        transient int modCount;
772 >        final TreeNode<V> getTreeNode(int h, Object k) {
773 >            return getTreeNode(h, k, root, comparableClassFor(k));
774 >        }
775  
776          /**
777 <         * The table is rehashed when its size exceeds this threshold.
778 <         * (The value of this field is always (int)(capacity *
214 <         * loadFactor).)
777 >         * Finds or adds a node. A front-end for recursive version
778 >         * @return null if added
779           */
780 <        private transient int threshold;
780 >        final TreeNode<V> putTreeNode(int h, Object k, V v) {
781 >            return putTreeNode(h, k, v, comparableClassFor(k));
782 >        }
783  
784          /**
785 <         * The per-segment table
785 >         * Returns the TreeNode (or null if not found) for the given key
786 >         * starting at given root.
787           */
788 <        transient HashEntry[] table;
788 >        @SuppressWarnings("unchecked") final TreeNode<V> getTreeNode
789 >            (int h, Object k, TreeNode<V> p, Class<?> cc) {
790 >            while (p != null) {
791 >                int dir, ph;  Object pk;
792 >                if ((ph = p.hash) != h)
793 >                    dir = (h < ph) ? -1 : 1;
794 >                else if ((pk = p.key) == k || k.equals(pk))
795 >                    return p;
796 >                else if ((dir = cccompare(cc, k, pk)) == 0) {
797 >                    TreeNode<V> r, pl, pr; // check both sides
798 >                    if ((pr = p.right) != null && h >= pr.hash &&
799 >                        (r = getTreeNode(h, k, pr, cc)) != null)
800 >                        return r;
801 >                    else if ((pl = p.left) != null && h <= pl.hash)
802 >                        dir = -1;
803 >                    else // nothing there
804 >                        break;
805 >                }
806 >                p = (dir > 0) ? p.right : p.left;
807 >            }
808 >            return null;
809 >        }
810  
811          /**
812 <         * The load factor for the hash table.  Even though this value
813 <         * is same for all segments, it is replicated to avoid needing
814 <         * links to outer object.
227 <         * @serial
812 >         * Wrapper for getTreeNode used by CHM.get. Tries to obtain
813 >         * read-lock to call getTreeNode, but during failure to get
814 >         * lock, searches along next links.
815           */
816 <        private final float loadFactor;
816 >        final V getValue(int h, Object k) {
817 >            Node<V> r = null;
818 >            int c = getState(); // Must read lock state first
819 >            for (Node<V> e = first; e != null; e = e.next) {
820 >                if (c <= 0 && compareAndSetState(c, c - 1)) {
821 >                    try {
822 >                        r = getTreeNode(h, k, root, comparableClassFor(k));
823 >                    } finally {
824 >                        releaseShared(0);
825 >                    }
826 >                    break;
827 >                }
828 >                else if (e.hash == h && k.equals(e.key)) {
829 >                    r = e;
830 >                    break;
831 >                }
832 >                else
833 >                    c = getState();
834 >            }
835 >            return r == null ? null : r.val;
836 >        }
837 >
838 >
839 >        /**
840 >         * recursive add.
841 >         * @return null if added
842 >         */
843 >        @SuppressWarnings("unchecked") final TreeNode<V> putTreeNode
844 >            (int h, Object k, V v, Class<?> cc) {
845 >            TreeNode<V> pp = root, p = null;
846 >            int dir = 0;
847 >            while (pp != null) { // find existing node or leaf to insert at
848 >                int ph;  Object pk;
849 >                p = pp;
850 >                if ((ph = p.hash) != h)
851 >                    dir = (h < ph) ? -1 : 1;
852 >                else if ((pk = p.key) == k || k.equals(pk))
853 >                    return p;
854 >                else if ((dir = cccompare(cc, k, pk)) == 0) {
855 >                    TreeNode<V> r, pr;
856 >                    if ((pr = p.right) != null && h >= pr.hash &&
857 >                        (r = getTreeNode(h, k, pr, cc)) != null)
858 >                        return r;
859 >                    else // continue left
860 >                        dir = -1;
861 >                }
862 >                pp = (dir > 0) ? p.right : p.left;
863 >            }
864  
865 <        Segment(int initialCapacity, float lf) {
866 <            loadFactor = lf;
867 <            setTable(new HashEntry[initialCapacity]);
865 >            TreeNode<V> f = first;
866 >            TreeNode<V> x = first = new TreeNode<V>(h, k, v, f, p);
867 >            if (p == null)
868 >                root = x;
869 >            else { // attach and rebalance; adapted from CLR
870 >                TreeNode<V> xp, xpp;
871 >                if (f != null)
872 >                    f.prev = x;
873 >                if (dir <= 0)
874 >                    p.left = x;
875 >                else
876 >                    p.right = x;
877 >                x.red = true;
878 >                while (x != null && (xp = x.parent) != null && xp.red &&
879 >                       (xpp = xp.parent) != null) {
880 >                    TreeNode<V> xppl = xpp.left;
881 >                    if (xp == xppl) {
882 >                        TreeNode<V> y = xpp.right;
883 >                        if (y != null && y.red) {
884 >                            y.red = false;
885 >                            xp.red = false;
886 >                            xpp.red = true;
887 >                            x = xpp;
888 >                        }
889 >                        else {
890 >                            if (x == xp.right) {
891 >                                rotateLeft(x = xp);
892 >                                xpp = (xp = x.parent) == null ? null : xp.parent;
893 >                            }
894 >                            if (xp != null) {
895 >                                xp.red = false;
896 >                                if (xpp != null) {
897 >                                    xpp.red = true;
898 >                                    rotateRight(xpp);
899 >                                }
900 >                            }
901 >                        }
902 >                    }
903 >                    else {
904 >                        TreeNode<V> y = xppl;
905 >                        if (y != null && y.red) {
906 >                            y.red = false;
907 >                            xp.red = false;
908 >                            xpp.red = true;
909 >                            x = xpp;
910 >                        }
911 >                        else {
912 >                            if (x == xp.left) {
913 >                                rotateRight(x = xp);
914 >                                xpp = (xp = x.parent) == null ? null : xp.parent;
915 >                            }
916 >                            if (xp != null) {
917 >                                xp.red = false;
918 >                                if (xpp != null) {
919 >                                    xpp.red = true;
920 >                                    rotateLeft(xpp);
921 >                                }
922 >                            }
923 >                        }
924 >                    }
925 >                }
926 >                TreeNode<V> r = root;
927 >                if (r != null && r.red)
928 >                    r.red = false;
929 >            }
930 >            return null;
931          }
932  
933          /**
934 <         * Set table to new HashEntry array.
935 <         * Call only while holding lock or in constructor.
936 <         **/
937 <        private void setTable(HashEntry[] newTable) {
938 <            table = newTable;
939 <            threshold = (int)(newTable.length * loadFactor);
940 <            count = count; // write-volatile
934 >         * Removes the given node, that must be present before this
935 >         * call.  This is messier than typical red-black deletion code
936 >         * because we cannot swap the contents of an interior node
937 >         * with a leaf successor that is pinned by "next" pointers
938 >         * that are accessible independently of lock. So instead we
939 >         * swap the tree linkages.
940 >         */
941 >        final void deleteTreeNode(TreeNode<V> p) {
942 >            TreeNode<V> next = (TreeNode<V>)p.next; // unlink traversal pointers
943 >            TreeNode<V> pred = p.prev;
944 >            if (pred == null)
945 >                first = next;
946 >            else
947 >                pred.next = next;
948 >            if (next != null)
949 >                next.prev = pred;
950 >            TreeNode<V> replacement;
951 >            TreeNode<V> pl = p.left;
952 >            TreeNode<V> pr = p.right;
953 >            if (pl != null && pr != null) {
954 >                TreeNode<V> s = pr, sl;
955 >                while ((sl = s.left) != null) // find successor
956 >                    s = sl;
957 >                boolean c = s.red; s.red = p.red; p.red = c; // swap colors
958 >                TreeNode<V> sr = s.right;
959 >                TreeNode<V> pp = p.parent;
960 >                if (s == pr) { // p was s's direct parent
961 >                    p.parent = s;
962 >                    s.right = p;
963 >                }
964 >                else {
965 >                    TreeNode<V> sp = s.parent;
966 >                    if ((p.parent = sp) != null) {
967 >                        if (s == sp.left)
968 >                            sp.left = p;
969 >                        else
970 >                            sp.right = p;
971 >                    }
972 >                    if ((s.right = pr) != null)
973 >                        pr.parent = s;
974 >                }
975 >                p.left = null;
976 >                if ((p.right = sr) != null)
977 >                    sr.parent = p;
978 >                if ((s.left = pl) != null)
979 >                    pl.parent = s;
980 >                if ((s.parent = pp) == null)
981 >                    root = s;
982 >                else if (p == pp.left)
983 >                    pp.left = s;
984 >                else
985 >                    pp.right = s;
986 >                replacement = sr;
987 >            }
988 >            else
989 >                replacement = (pl != null) ? pl : pr;
990 >            TreeNode<V> pp = p.parent;
991 >            if (replacement == null) {
992 >                if (pp == null) {
993 >                    root = null;
994 >                    return;
995 >                }
996 >                replacement = p;
997 >            }
998 >            else {
999 >                replacement.parent = pp;
1000 >                if (pp == null)
1001 >                    root = replacement;
1002 >                else if (p == pp.left)
1003 >                    pp.left = replacement;
1004 >                else
1005 >                    pp.right = replacement;
1006 >                p.left = p.right = p.parent = null;
1007 >            }
1008 >            if (!p.red) { // rebalance, from CLR
1009 >                TreeNode<V> x = replacement;
1010 >                while (x != null) {
1011 >                    TreeNode<V> xp, xpl;
1012 >                    if (x.red || (xp = x.parent) == null) {
1013 >                        x.red = false;
1014 >                        break;
1015 >                    }
1016 >                    if (x == (xpl = xp.left)) {
1017 >                        TreeNode<V> sib = xp.right;
1018 >                        if (sib != null && sib.red) {
1019 >                            sib.red = false;
1020 >                            xp.red = true;
1021 >                            rotateLeft(xp);
1022 >                            sib = (xp = x.parent) == null ? null : xp.right;
1023 >                        }
1024 >                        if (sib == null)
1025 >                            x = xp;
1026 >                        else {
1027 >                            TreeNode<V> sl = sib.left, sr = sib.right;
1028 >                            if ((sr == null || !sr.red) &&
1029 >                                (sl == null || !sl.red)) {
1030 >                                sib.red = true;
1031 >                                x = xp;
1032 >                            }
1033 >                            else {
1034 >                                if (sr == null || !sr.red) {
1035 >                                    if (sl != null)
1036 >                                        sl.red = false;
1037 >                                    sib.red = true;
1038 >                                    rotateRight(sib);
1039 >                                    sib = (xp = x.parent) == null ?
1040 >                                        null : xp.right;
1041 >                                }
1042 >                                if (sib != null) {
1043 >                                    sib.red = (xp == null) ? false : xp.red;
1044 >                                    if ((sr = sib.right) != null)
1045 >                                        sr.red = false;
1046 >                                }
1047 >                                if (xp != null) {
1048 >                                    xp.red = false;
1049 >                                    rotateLeft(xp);
1050 >                                }
1051 >                                x = root;
1052 >                            }
1053 >                        }
1054 >                    }
1055 >                    else { // symmetric
1056 >                        TreeNode<V> sib = xpl;
1057 >                        if (sib != null && sib.red) {
1058 >                            sib.red = false;
1059 >                            xp.red = true;
1060 >                            rotateRight(xp);
1061 >                            sib = (xp = x.parent) == null ? null : xp.left;
1062 >                        }
1063 >                        if (sib == null)
1064 >                            x = xp;
1065 >                        else {
1066 >                            TreeNode<V> sl = sib.left, sr = sib.right;
1067 >                            if ((sl == null || !sl.red) &&
1068 >                                (sr == null || !sr.red)) {
1069 >                                sib.red = true;
1070 >                                x = xp;
1071 >                            }
1072 >                            else {
1073 >                                if (sl == null || !sl.red) {
1074 >                                    if (sr != null)
1075 >                                        sr.red = false;
1076 >                                    sib.red = true;
1077 >                                    rotateLeft(sib);
1078 >                                    sib = (xp = x.parent) == null ?
1079 >                                        null : xp.left;
1080 >                                }
1081 >                                if (sib != null) {
1082 >                                    sib.red = (xp == null) ? false : xp.red;
1083 >                                    if ((sl = sib.left) != null)
1084 >                                        sl.red = false;
1085 >                                }
1086 >                                if (xp != null) {
1087 >                                    xp.red = false;
1088 >                                    rotateRight(xp);
1089 >                                }
1090 >                                x = root;
1091 >                            }
1092 >                        }
1093 >                    }
1094 >                }
1095 >            }
1096 >            if (p == replacement && (pp = p.parent) != null) {
1097 >                if (p == pp.left) // detach pointers
1098 >                    pp.left = null;
1099 >                else if (p == pp.right)
1100 >                    pp.right = null;
1101 >                p.parent = null;
1102 >            }
1103          }
1104 +    }
1105  
1106 <        /* Specialized implementations of map methods */
1106 >    /* ---------------- Collision reduction methods -------------- */
1107  
1108 <        V get(K key, int hash) {
1109 <            if (count != 0) { // read-volatile
1110 <                HashEntry[] tab = table;
1111 <                int index = hash & (tab.length - 1);
1112 <                HashEntry<K,V> e = (HashEntry<K,V>) tab[index];
1113 <                while (e != null) {
1114 <                    if (e.hash == hash && key.equals(e.key))
1115 <                        return e.value;
1116 <                    e = e.next;
1108 >    /**
1109 >     * Spreads higher bits to lower, and also forces top bit to 0.
1110 >     * Because the table uses power-of-two masking, sets of hashes
1111 >     * that vary only in bits above the current mask will always
1112 >     * collide. (Among known examples are sets of Float keys holding
1113 >     * consecutive whole numbers in small tables.)  To counter this,
1114 >     * we apply a transform that spreads the impact of higher bits
1115 >     * downward. There is a tradeoff between speed, utility, and
1116 >     * quality of bit-spreading. Because many common sets of hashes
1117 >     * are already reasonably distributed across bits (so don't benefit
1118 >     * from spreading), and because we use trees to handle large sets
1119 >     * of collisions in bins, we don't need excessively high quality.
1120 >     */
1121 >    private static final int spread(int h) {
1122 >        h ^= (h >>> 18) ^ (h >>> 12);
1123 >        return (h ^ (h >>> 10)) & HASH_BITS;
1124 >    }
1125 >
1126 >    /**
1127 >     * Replaces a list bin with a tree bin if key is comparable.  Call
1128 >     * only when locked.
1129 >     */
1130 >    private final void replaceWithTreeBin(Node<V>[] tab, int index, Object key) {
1131 >        if (comparableClassFor(key) != null) {
1132 >            TreeBin<V> t = new TreeBin<V>();
1133 >            for (Node<V> e = tabAt(tab, index); e != null; e = e.next)
1134 >                t.putTreeNode(e.hash, e.key, e.val);
1135 >            setTabAt(tab, index, new Node<V>(MOVED, t, null, null));
1136 >        }
1137 >    }
1138 >
1139 >    /* ---------------- Internal access and update methods -------------- */
1140 >
1141 >    /** Implementation for get and containsKey */
1142 >    @SuppressWarnings("unchecked") private final V internalGet(Object k) {
1143 >        int h = spread(k.hashCode());
1144 >        retry: for (Node<V>[] tab = table; tab != null;) {
1145 >            Node<V> e; Object ek; V ev; int eh; // locals to read fields once
1146 >            for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) {
1147 >                if ((eh = e.hash) < 0) {
1148 >                    if ((ek = e.key) instanceof TreeBin)  // search TreeBin
1149 >                        return ((TreeBin<V>)ek).getValue(h, k);
1150 >                    else {                      // restart with new table
1151 >                        tab = (Node<V>[])ek;
1152 >                        continue retry;
1153 >                    }
1154                  }
1155 +                else if (eh == h && (ev = e.val) != null &&
1156 +                         ((ek = e.key) == k || k.equals(ek)))
1157 +                    return ev;
1158              }
1159 <            return null;
1159 >            break;
1160          }
1161 +        return null;
1162 +    }
1163  
1164 <        boolean containsKey(Object key, int hash) {
1165 <            if (count != 0) { // read-volatile
1166 <                HashEntry[] tab = table;
1167 <                int index = hash & (tab.length - 1);
1168 <                HashEntry<K,V> e = (HashEntry<K,V>) tab[index];
1169 <                while (e != null) {
1170 <                    if (e.hash == hash && key.equals(e.key))
1171 <                        return true;
1172 <                    e = e.next;
1164 >    /**
1165 >     * Implementation for the four public remove/replace methods:
1166 >     * Replaces node value with v, conditional upon match of cv if
1167 >     * non-null.  If resulting value is null, delete.
1168 >     */
1169 >    @SuppressWarnings("unchecked") private final V internalReplace
1170 >        (Object k, V v, Object cv) {
1171 >        int h = spread(k.hashCode());
1172 >        V oldVal = null;
1173 >        for (Node<V>[] tab = table;;) {
1174 >            Node<V> f; int i, fh; Object fk;
1175 >            if (tab == null ||
1176 >                (f = tabAt(tab, i = (tab.length - 1) & h)) == null)
1177 >                break;
1178 >            else if ((fh = f.hash) < 0) {
1179 >                if ((fk = f.key) instanceof TreeBin) {
1180 >                    TreeBin<V> t = (TreeBin<V>)fk;
1181 >                    boolean validated = false;
1182 >                    boolean deleted = false;
1183 >                    t.acquire(0);
1184 >                    try {
1185 >                        if (tabAt(tab, i) == f) {
1186 >                            validated = true;
1187 >                            TreeNode<V> p = t.getTreeNode(h, k);
1188 >                            if (p != null) {
1189 >                                V pv = p.val;
1190 >                                if (cv == null || cv == pv || cv.equals(pv)) {
1191 >                                    oldVal = pv;
1192 >                                    if ((p.val = v) == null) {
1193 >                                        deleted = true;
1194 >                                        t.deleteTreeNode(p);
1195 >                                    }
1196 >                                }
1197 >                            }
1198 >                        }
1199 >                    } finally {
1200 >                        t.release(0);
1201 >                    }
1202 >                    if (validated) {
1203 >                        if (deleted)
1204 >                            addCount(-1L, -1);
1205 >                        break;
1206 >                    }
1207 >                }
1208 >                else
1209 >                    tab = (Node<V>[])fk;
1210 >            }
1211 >            else if (fh != h && f.next == null) // precheck
1212 >                break;                          // rules out possible existence
1213 >            else {
1214 >                boolean validated = false;
1215 >                boolean deleted = false;
1216 >                synchronized (f) {
1217 >                    if (tabAt(tab, i) == f) {
1218 >                        validated = true;
1219 >                        for (Node<V> e = f, pred = null;;) {
1220 >                            Object ek; V ev;
1221 >                            if (e.hash == h &&
1222 >                                ((ev = e.val) != null) &&
1223 >                                ((ek = e.key) == k || k.equals(ek))) {
1224 >                                if (cv == null || cv == ev || cv.equals(ev)) {
1225 >                                    oldVal = ev;
1226 >                                    if ((e.val = v) == null) {
1227 >                                        deleted = true;
1228 >                                        Node<V> en = e.next;
1229 >                                        if (pred != null)
1230 >                                            pred.next = en;
1231 >                                        else
1232 >                                            setTabAt(tab, i, en);
1233 >                                    }
1234 >                                }
1235 >                                break;
1236 >                            }
1237 >                            pred = e;
1238 >                            if ((e = e.next) == null)
1239 >                                break;
1240 >                        }
1241 >                    }
1242 >                }
1243 >                if (validated) {
1244 >                    if (deleted)
1245 >                        addCount(-1L, -1);
1246 >                    break;
1247                  }
1248              }
273            return false;
1249          }
1250 +        return oldVal;
1251 +    }
1252  
1253 <        boolean containsValue(Object value) {
1254 <            if (count != 0) { // read-volatile
1255 <                HashEntry[] tab = table;
1256 <                int len = tab.length;
1257 <                for (int i = 0 ; i < len; i++)
1258 <                    for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i] ; e != null ; e = e.next)
1259 <                        if (value.equals(e.value))
1260 <                            return true;
1253 >    /*
1254 >     * Internal versions of insertion methods
1255 >     * All have the same basic structure as the first (internalPut):
1256 >     *  1. If table uninitialized, create
1257 >     *  2. If bin empty, try to CAS new node
1258 >     *  3. If bin stale, use new table
1259 >     *  4. if bin converted to TreeBin, validate and relay to TreeBin methods
1260 >     *  5. Lock and validate; if valid, scan and add or update
1261 >     *
1262 >     * The putAll method differs mainly in attempting to pre-allocate
1263 >     * enough table space, and also more lazily performs count updates
1264 >     * and checks.
1265 >     *
1266 >     * Most of the function-accepting methods can't be factored nicely
1267 >     * because they require different functional forms, so instead
1268 >     * sprawl out similar mechanics.
1269 >     */
1270 >
1271 >    /** Implementation for put and putIfAbsent */
1272 >    @SuppressWarnings("unchecked") private final V internalPut
1273 >        (K k, V v, boolean onlyIfAbsent) {
1274 >        if (k == null || v == null) throw new NullPointerException();
1275 >        int h = spread(k.hashCode());
1276 >        int len = 0;
1277 >        for (Node<V>[] tab = table;;) {
1278 >            int i, fh; Node<V> f; Object fk; V fv;
1279 >            if (tab == null)
1280 >                tab = initTable();
1281 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1282 >                if (casTabAt(tab, i, null, new Node<V>(h, k, v, null)))
1283 >                    break;                   // no lock when adding to empty bin
1284 >            }
1285 >            else if ((fh = f.hash) < 0) {
1286 >                if ((fk = f.key) instanceof TreeBin) {
1287 >                    TreeBin<V> t = (TreeBin<V>)fk;
1288 >                    V oldVal = null;
1289 >                    t.acquire(0);
1290 >                    try {
1291 >                        if (tabAt(tab, i) == f) {
1292 >                            len = 2;
1293 >                            TreeNode<V> p = t.putTreeNode(h, k, v);
1294 >                            if (p != null) {
1295 >                                oldVal = p.val;
1296 >                                if (!onlyIfAbsent)
1297 >                                    p.val = v;
1298 >                            }
1299 >                        }
1300 >                    } finally {
1301 >                        t.release(0);
1302 >                    }
1303 >                    if (len != 0) {
1304 >                        if (oldVal != null)
1305 >                            return oldVal;
1306 >                        break;
1307 >                    }
1308 >                }
1309 >                else
1310 >                    tab = (Node<V>[])fk;
1311 >            }
1312 >            else if (onlyIfAbsent && fh == h && (fv = f.val) != null &&
1313 >                     ((fk = f.key) == k || k.equals(fk))) // peek while nearby
1314 >                return fv;
1315 >            else {
1316 >                V oldVal = null;
1317 >                synchronized (f) {
1318 >                    if (tabAt(tab, i) == f) {
1319 >                        len = 1;
1320 >                        for (Node<V> e = f;; ++len) {
1321 >                            Object ek; V ev;
1322 >                            if (e.hash == h &&
1323 >                                (ev = e.val) != null &&
1324 >                                ((ek = e.key) == k || k.equals(ek))) {
1325 >                                oldVal = ev;
1326 >                                if (!onlyIfAbsent)
1327 >                                    e.val = v;
1328 >                                break;
1329 >                            }
1330 >                            Node<V> last = e;
1331 >                            if ((e = e.next) == null) {
1332 >                                last.next = new Node<V>(h, k, v, null);
1333 >                                if (len >= TREE_THRESHOLD)
1334 >                                    replaceWithTreeBin(tab, i, k);
1335 >                                break;
1336 >                            }
1337 >                        }
1338 >                    }
1339 >                }
1340 >                if (len != 0) {
1341 >                    if (oldVal != null)
1342 >                        return oldVal;
1343 >                    break;
1344 >                }
1345              }
285            return false;
1346          }
1347 +        addCount(1L, len);
1348 +        return null;
1349 +    }
1350  
1351 <        V put(K key, int hash, V value, boolean onlyIfAbsent) {
1352 <            lock();
1353 <            try {
1354 <                int c = count;
1355 <                HashEntry[] tab = table;
1356 <                int index = hash & (tab.length - 1);
1357 <                HashEntry<K,V> first = (HashEntry<K,V>) tab[index];
1358 <
1359 <                for (HashEntry<K,V> e = first; e != null; e = (HashEntry<K,V>) e.next) {
1360 <                    if (e.hash == hash && key.equals(e.key)) {
1361 <                        V oldValue = e.value;
1362 <                        if (!onlyIfAbsent)
1363 <                            e.value = value;
1364 <                        ++modCount;
1365 <                        count = c; // write-volatile
1366 <                        return oldValue;
1351 >    /** Implementation for computeIfAbsent */
1352 >    @SuppressWarnings("unchecked") private final V internalComputeIfAbsent
1353 >        (K k, Function<? super K, ? extends V> mf) {
1354 >        if (k == null || mf == null)
1355 >            throw new NullPointerException();
1356 >        int h = spread(k.hashCode());
1357 >        V val = null;
1358 >        int len = 0;
1359 >        for (Node<V>[] tab = table;;) {
1360 >            Node<V> f; int i; Object fk;
1361 >            if (tab == null)
1362 >                tab = initTable();
1363 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1364 >                Node<V> node = new Node<V>(h, k, null, null);
1365 >                synchronized (node) {
1366 >                    if (casTabAt(tab, i, null, node)) {
1367 >                        len = 1;
1368 >                        try {
1369 >                            if ((val = mf.apply(k)) != null)
1370 >                                node.val = val;
1371 >                        } finally {
1372 >                            if (val == null)
1373 >                                setTabAt(tab, i, null);
1374 >                        }
1375 >                    }
1376 >                }
1377 >                if (len != 0)
1378 >                    break;
1379 >            }
1380 >            else if (f.hash < 0) {
1381 >                if ((fk = f.key) instanceof TreeBin) {
1382 >                    TreeBin<V> t = (TreeBin<V>)fk;
1383 >                    boolean added = false;
1384 >                    t.acquire(0);
1385 >                    try {
1386 >                        if (tabAt(tab, i) == f) {
1387 >                            len = 1;
1388 >                            TreeNode<V> p = t.getTreeNode(h, k);
1389 >                            if (p != null)
1390 >                                val = p.val;
1391 >                            else if ((val = mf.apply(k)) != null) {
1392 >                                added = true;
1393 >                                len = 2;
1394 >                                t.putTreeNode(h, k, val);
1395 >                            }
1396 >                        }
1397 >                    } finally {
1398 >                        t.release(0);
1399 >                    }
1400 >                    if (len != 0) {
1401 >                        if (!added)
1402 >                            return val;
1403 >                        break;
1404 >                    }
1405 >                }
1406 >                else
1407 >                    tab = (Node<V>[])fk;
1408 >            }
1409 >            else {
1410 >                for (Node<V> e = f; e != null; e = e.next) { // prescan
1411 >                    Object ek; V ev;
1412 >                    if (e.hash == h && (ev = e.val) != null &&
1413 >                        ((ek = e.key) == k || k.equals(ek)))
1414 >                        return ev;
1415 >                }
1416 >                boolean added = false;
1417 >                synchronized (f) {
1418 >                    if (tabAt(tab, i) == f) {
1419 >                        len = 1;
1420 >                        for (Node<V> e = f;; ++len) {
1421 >                            Object ek; V ev;
1422 >                            if (e.hash == h &&
1423 >                                (ev = e.val) != null &&
1424 >                                ((ek = e.key) == k || k.equals(ek))) {
1425 >                                val = ev;
1426 >                                break;
1427 >                            }
1428 >                            Node<V> last = e;
1429 >                            if ((e = e.next) == null) {
1430 >                                if ((val = mf.apply(k)) != null) {
1431 >                                    added = true;
1432 >                                    last.next = new Node<V>(h, k, val, null);
1433 >                                    if (len >= TREE_THRESHOLD)
1434 >                                        replaceWithTreeBin(tab, i, k);
1435 >                                }
1436 >                                break;
1437 >                            }
1438 >                        }
1439                      }
1440                  }
1441 +                if (len != 0) {
1442 +                    if (!added)
1443 +                        return val;
1444 +                    break;
1445 +                }
1446 +            }
1447 +        }
1448 +        if (val != null)
1449 +            addCount(1L, len);
1450 +        return val;
1451 +    }
1452  
1453 <                tab[index] = new HashEntry<K,V>(hash, key, value, first);
1454 <                ++modCount;
1455 <                ++c;
1456 <                count = c; // write-volatile
1457 <                if (c > threshold)
1458 <                    setTable(rehash(tab));
1459 <                return null;
1460 <            } finally {
1461 <                unlock();
1453 >    /** Implementation for compute */
1454 >    @SuppressWarnings("unchecked") private final V internalCompute
1455 >        (K k, boolean onlyIfPresent,
1456 >         BiFunction<? super K, ? super V, ? extends V> mf) {
1457 >        if (k == null || mf == null)
1458 >            throw new NullPointerException();
1459 >        int h = spread(k.hashCode());
1460 >        V val = null;
1461 >        int delta = 0;
1462 >        int len = 0;
1463 >        for (Node<V>[] tab = table;;) {
1464 >            Node<V> f; int i, fh; Object fk;
1465 >            if (tab == null)
1466 >                tab = initTable();
1467 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1468 >                if (onlyIfPresent)
1469 >                    break;
1470 >                Node<V> node = new Node<V>(h, k, null, null);
1471 >                synchronized (node) {
1472 >                    if (casTabAt(tab, i, null, node)) {
1473 >                        try {
1474 >                            len = 1;
1475 >                            if ((val = mf.apply(k, null)) != null) {
1476 >                                node.val = val;
1477 >                                delta = 1;
1478 >                            }
1479 >                        } finally {
1480 >                            if (delta == 0)
1481 >                                setTabAt(tab, i, null);
1482 >                        }
1483 >                    }
1484 >                }
1485 >                if (len != 0)
1486 >                    break;
1487 >            }
1488 >            else if ((fh = f.hash) < 0) {
1489 >                if ((fk = f.key) instanceof TreeBin) {
1490 >                    TreeBin<V> t = (TreeBin<V>)fk;
1491 >                    t.acquire(0);
1492 >                    try {
1493 >                        if (tabAt(tab, i) == f) {
1494 >                            len = 1;
1495 >                            TreeNode<V> p = t.getTreeNode(h, k);
1496 >                            if (p == null && onlyIfPresent)
1497 >                                break;
1498 >                            V pv = (p == null) ? null : p.val;
1499 >                            if ((val = mf.apply(k, pv)) != null) {
1500 >                                if (p != null)
1501 >                                    p.val = val;
1502 >                                else {
1503 >                                    len = 2;
1504 >                                    delta = 1;
1505 >                                    t.putTreeNode(h, k, val);
1506 >                                }
1507 >                            }
1508 >                            else if (p != null) {
1509 >                                delta = -1;
1510 >                                t.deleteTreeNode(p);
1511 >                            }
1512 >                        }
1513 >                    } finally {
1514 >                        t.release(0);
1515 >                    }
1516 >                    if (len != 0)
1517 >                        break;
1518 >                }
1519 >                else
1520 >                    tab = (Node<V>[])fk;
1521 >            }
1522 >            else {
1523 >                synchronized (f) {
1524 >                    if (tabAt(tab, i) == f) {
1525 >                        len = 1;
1526 >                        for (Node<V> e = f, pred = null;; ++len) {
1527 >                            Object ek; V ev;
1528 >                            if (e.hash == h &&
1529 >                                (ev = e.val) != null &&
1530 >                                ((ek = e.key) == k || k.equals(ek))) {
1531 >                                val = mf.apply(k, ev);
1532 >                                if (val != null)
1533 >                                    e.val = val;
1534 >                                else {
1535 >                                    delta = -1;
1536 >                                    Node<V> en = e.next;
1537 >                                    if (pred != null)
1538 >                                        pred.next = en;
1539 >                                    else
1540 >                                        setTabAt(tab, i, en);
1541 >                                }
1542 >                                break;
1543 >                            }
1544 >                            pred = e;
1545 >                            if ((e = e.next) == null) {
1546 >                                if (!onlyIfPresent &&
1547 >                                    (val = mf.apply(k, null)) != null) {
1548 >                                    pred.next = new Node<V>(h, k, val, null);
1549 >                                    delta = 1;
1550 >                                    if (len >= TREE_THRESHOLD)
1551 >                                        replaceWithTreeBin(tab, i, k);
1552 >                                }
1553 >                                break;
1554 >                            }
1555 >                        }
1556 >                    }
1557 >                }
1558 >                if (len != 0)
1559 >                    break;
1560              }
1561          }
1562 +        if (delta != 0)
1563 +            addCount((long)delta, len);
1564 +        return val;
1565 +    }
1566  
1567 <        private HashEntry[] rehash(HashEntry[] oldTable) {
1568 <            int oldCapacity = oldTable.length;
1569 <            if (oldCapacity >= MAXIMUM_CAPACITY)
1570 <                return oldTable;
1571 <
1572 <            /*
1573 <             * Reclassify nodes in each list to new Map.  Because we are
1574 <             * using power-of-two expansion, the elements from each bin
1575 <             * must either stay at same index, or move with a power of two
1576 <             * offset. We eliminate unnecessary node creation by catching
1577 <             * cases where old nodes can be reused because their next
1578 <             * fields won't change. Statistically, at the default
1579 <             * threshhold, only about one-sixth of them need cloning when
1580 <             * a table doubles. The nodes they replace will be garbage
1581 <             * collectable as soon as they are no longer referenced by any
1582 <             * reader thread that may be in the midst of traversing table
1583 <             * right now.
1584 <             */
1585 <
1586 <            HashEntry[] newTable = new HashEntry[oldCapacity << 1];
1587 <            int sizeMask = newTable.length - 1;
1588 <            for (int i = 0; i < oldCapacity ; i++) {
1589 <                // We need to guarantee that any existing reads of old Map can
1590 <                //  proceed. So we cannot yet null out each bin.
1591 <                HashEntry<K,V> e = (HashEntry<K,V>)oldTable[i];
1592 <
1593 <                if (e != null) {
1594 <                    HashEntry<K,V> next = e.next;
1595 <                    int idx = e.hash & sizeMask;
1596 <
1597 <                    //  Single node on list
1598 <                    if (next == null)
1599 <                        newTable[idx] = e;
1567 >    /** Implementation for merge */
1568 >    @SuppressWarnings("unchecked") private final V internalMerge
1569 >        (K k, V v, BiFunction<? super V, ? super V, ? extends V> mf) {
1570 >        if (k == null || v == null || mf == null)
1571 >            throw new NullPointerException();
1572 >        int h = spread(k.hashCode());
1573 >        V val = null;
1574 >        int delta = 0;
1575 >        int len = 0;
1576 >        for (Node<V>[] tab = table;;) {
1577 >            int i; Node<V> f; Object fk; V fv;
1578 >            if (tab == null)
1579 >                tab = initTable();
1580 >            else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1581 >                if (casTabAt(tab, i, null, new Node<V>(h, k, v, null))) {
1582 >                    delta = 1;
1583 >                    val = v;
1584 >                    break;
1585 >                }
1586 >            }
1587 >            else if (f.hash < 0) {
1588 >                if ((fk = f.key) instanceof TreeBin) {
1589 >                    TreeBin<V> t = (TreeBin<V>)fk;
1590 >                    t.acquire(0);
1591 >                    try {
1592 >                        if (tabAt(tab, i) == f) {
1593 >                            len = 1;
1594 >                            TreeNode<V> p = t.getTreeNode(h, k);
1595 >                            val = (p == null) ? v : mf.apply(p.val, v);
1596 >                            if (val != null) {
1597 >                                if (p != null)
1598 >                                    p.val = val;
1599 >                                else {
1600 >                                    len = 2;
1601 >                                    delta = 1;
1602 >                                    t.putTreeNode(h, k, val);
1603 >                                }
1604 >                            }
1605 >                            else if (p != null) {
1606 >                                delta = -1;
1607 >                                t.deleteTreeNode(p);
1608 >                            }
1609 >                        }
1610 >                    } finally {
1611 >                        t.release(0);
1612 >                    }
1613 >                    if (len != 0)
1614 >                        break;
1615 >                }
1616 >                else
1617 >                    tab = (Node<V>[])fk;
1618 >            }
1619 >            else {
1620 >                synchronized (f) {
1621 >                    if (tabAt(tab, i) == f) {
1622 >                        len = 1;
1623 >                        for (Node<V> e = f, pred = null;; ++len) {
1624 >                            Object ek; V ev;
1625 >                            if (e.hash == h &&
1626 >                                (ev = e.val) != null &&
1627 >                                ((ek = e.key) == k || k.equals(ek))) {
1628 >                                val = mf.apply(ev, v);
1629 >                                if (val != null)
1630 >                                    e.val = val;
1631 >                                else {
1632 >                                    delta = -1;
1633 >                                    Node<V> en = e.next;
1634 >                                    if (pred != null)
1635 >                                        pred.next = en;
1636 >                                    else
1637 >                                        setTabAt(tab, i, en);
1638 >                                }
1639 >                                break;
1640 >                            }
1641 >                            pred = e;
1642 >                            if ((e = e.next) == null) {
1643 >                                val = v;
1644 >                                pred.next = new Node<V>(h, k, val, null);
1645 >                                delta = 1;
1646 >                                if (len >= TREE_THRESHOLD)
1647 >                                    replaceWithTreeBin(tab, i, k);
1648 >                                break;
1649 >                            }
1650 >                        }
1651 >                    }
1652 >                }
1653 >                if (len != 0)
1654 >                    break;
1655 >            }
1656 >        }
1657 >        if (delta != 0)
1658 >            addCount((long)delta, len);
1659 >        return val;
1660 >    }
1661  
1662 +    /** Implementation for putAll */
1663 +    @SuppressWarnings("unchecked") private final void internalPutAll
1664 +        (Map<? extends K, ? extends V> m) {
1665 +        tryPresize(m.size());
1666 +        long delta = 0L;     // number of uncommitted additions
1667 +        boolean npe = false; // to throw exception on exit for nulls
1668 +        try {                // to clean up counts on other exceptions
1669 +            for (Map.Entry<?, ? extends V> entry : m.entrySet()) {
1670 +                Object k; V v;
1671 +                if (entry == null || (k = entry.getKey()) == null ||
1672 +                    (v = entry.getValue()) == null) {
1673 +                    npe = true;
1674 +                    break;
1675 +                }
1676 +                int h = spread(k.hashCode());
1677 +                for (Node<V>[] tab = table;;) {
1678 +                    int i; Node<V> f; int fh; Object fk;
1679 +                    if (tab == null)
1680 +                        tab = initTable();
1681 +                    else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
1682 +                        if (casTabAt(tab, i, null, new Node<V>(h, k, v, null))) {
1683 +                            ++delta;
1684 +                            break;
1685 +                        }
1686 +                    }
1687 +                    else if ((fh = f.hash) < 0) {
1688 +                        if ((fk = f.key) instanceof TreeBin) {
1689 +                            TreeBin<V> t = (TreeBin<V>)fk;
1690 +                            boolean validated = false;
1691 +                            t.acquire(0);
1692 +                            try {
1693 +                                if (tabAt(tab, i) == f) {
1694 +                                    validated = true;
1695 +                                    TreeNode<V> p = t.getTreeNode(h, k);
1696 +                                    if (p != null)
1697 +                                        p.val = v;
1698 +                                    else {
1699 +                                        t.putTreeNode(h, k, v);
1700 +                                        ++delta;
1701 +                                    }
1702 +                                }
1703 +                            } finally {
1704 +                                t.release(0);
1705 +                            }
1706 +                            if (validated)
1707 +                                break;
1708 +                        }
1709 +                        else
1710 +                            tab = (Node<V>[])fk;
1711 +                    }
1712                      else {
1713 <                        // Reuse trailing consecutive sequence at same slot
1714 <                        HashEntry<K,V> lastRun = e;
1715 <                        int lastIdx = idx;
1716 <                        for (HashEntry<K,V> last = next;
1717 <                             last != null;
1718 <                             last = last.next) {
1719 <                            int k = last.hash & sizeMask;
1720 <                            if (k != lastIdx) {
1721 <                                lastIdx = k;
1722 <                                lastRun = last;
1713 >                        int len = 0;
1714 >                        synchronized (f) {
1715 >                            if (tabAt(tab, i) == f) {
1716 >                                len = 1;
1717 >                                for (Node<V> e = f;; ++len) {
1718 >                                    Object ek; V ev;
1719 >                                    if (e.hash == h &&
1720 >                                        (ev = e.val) != null &&
1721 >                                        ((ek = e.key) == k || k.equals(ek))) {
1722 >                                        e.val = v;
1723 >                                        break;
1724 >                                    }
1725 >                                    Node<V> last = e;
1726 >                                    if ((e = e.next) == null) {
1727 >                                        ++delta;
1728 >                                        last.next = new Node<V>(h, k, v, null);
1729 >                                        if (len >= TREE_THRESHOLD)
1730 >                                            replaceWithTreeBin(tab, i, k);
1731 >                                        break;
1732 >                                    }
1733 >                                }
1734                              }
1735                          }
1736 <                        newTable[lastIdx] = lastRun;
1736 >                        if (len != 0) {
1737 >                            if (len > 1) {
1738 >                                addCount(delta, len);
1739 >                                delta = 0L;
1740 >                            }
1741 >                            break;
1742 >                        }
1743 >                    }
1744 >                }
1745 >            }
1746 >        } finally {
1747 >            if (delta != 0L)
1748 >                addCount(delta, 2);
1749 >        }
1750 >        if (npe)
1751 >            throw new NullPointerException();
1752 >    }
1753  
1754 <                        // Clone all remaining nodes
1755 <                        for (HashEntry<K,V> p = e; p != lastRun; p = p.next) {
1756 <                            int k = p.hash & sizeMask;
1757 <                            newTable[k] = new HashEntry<K,V>(p.hash,
1758 <                                                             p.key,
1759 <                                                             p.value,
1760 <                                                             (HashEntry<K,V>) newTable[k]);
1754 >    /**
1755 >     * Implementation for clear. Steps through each bin, removing all
1756 >     * nodes.
1757 >     */
1758 >    @SuppressWarnings("unchecked") private final void internalClear() {
1759 >        long delta = 0L; // negative number of deletions
1760 >        int i = 0;
1761 >        Node<V>[] tab = table;
1762 >        while (tab != null && i < tab.length) {
1763 >            Node<V> f = tabAt(tab, i);
1764 >            if (f == null)
1765 >                ++i;
1766 >            else if (f.hash < 0) {
1767 >                Object fk;
1768 >                if ((fk = f.key) instanceof TreeBin) {
1769 >                    TreeBin<V> t = (TreeBin<V>)fk;
1770 >                    t.acquire(0);
1771 >                    try {
1772 >                        if (tabAt(tab, i) == f) {
1773 >                            for (Node<V> p = t.first; p != null; p = p.next) {
1774 >                                if (p.val != null) { // (currently always true)
1775 >                                    p.val = null;
1776 >                                    --delta;
1777 >                                }
1778 >                            }
1779 >                            t.first = null;
1780 >                            t.root = null;
1781 >                            ++i;
1782 >                        }
1783 >                    } finally {
1784 >                        t.release(0);
1785 >                    }
1786 >                }
1787 >                else
1788 >                    tab = (Node<V>[])fk;
1789 >            }
1790 >            else {
1791 >                synchronized (f) {
1792 >                    if (tabAt(tab, i) == f) {
1793 >                        for (Node<V> e = f; e != null; e = e.next) {
1794 >                            if (e.val != null) {  // (currently always true)
1795 >                                e.val = null;
1796 >                                --delta;
1797 >                            }
1798                          }
1799 +                        setTabAt(tab, i, null);
1800 +                        ++i;
1801                      }
1802                  }
1803              }
379            return newTable;
1804          }
1805 +        if (delta != 0L)
1806 +            addCount(delta, -1);
1807 +    }
1808  
1809 <        /**
383 <         * Remove; match on key only if value null, else match both.
384 <         */
385 <        V remove(Object key, int hash, Object value) {
386 <            lock();
387 <            try {
388 <                int c = count;
389 <                HashEntry[] tab = table;
390 <                int index = hash & (tab.length - 1);
391 <                HashEntry<K,V> first = (HashEntry<K,V>)tab[index];
1809 >    /* ---------------- Table Initialization and Resizing -------------- */
1810  
1811 <                HashEntry<K,V> e = first;
1812 <                for (;;) {
1813 <                    if (e == null)
1814 <                        return null;
1815 <                    if (e.hash == hash && key.equals(e.key))
1811 >    /**
1812 >     * Returns a power of two table size for the given desired capacity.
1813 >     * See Hackers Delight, sec 3.2
1814 >     */
1815 >    private static final int tableSizeFor(int c) {
1816 >        int n = c - 1;
1817 >        n |= n >>> 1;
1818 >        n |= n >>> 2;
1819 >        n |= n >>> 4;
1820 >        n |= n >>> 8;
1821 >        n |= n >>> 16;
1822 >        return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
1823 >    }
1824 >
1825 >    /**
1826 >     * Initializes table, using the size recorded in sizeCtl.
1827 >     */
1828 >    @SuppressWarnings("unchecked") private final Node<V>[] initTable() {
1829 >        Node<V>[] tab; int sc;
1830 >        while ((tab = table) == null) {
1831 >            if ((sc = sizeCtl) < 0)
1832 >                Thread.yield(); // lost initialization race; just spin
1833 >            else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
1834 >                try {
1835 >                    if ((tab = table) == null) {
1836 >                        int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
1837 >                        @SuppressWarnings("rawtypes") Node[] tb = new Node[n];
1838 >                        table = tab = (Node<V>[])tb;
1839 >                        sc = n - (n >>> 2);
1840 >                    }
1841 >                } finally {
1842 >                    sizeCtl = sc;
1843 >                }
1844 >                break;
1845 >            }
1846 >        }
1847 >        return tab;
1848 >    }
1849 >
1850 >    /**
1851 >     * Adds to count, and if table is too small and not already
1852 >     * resizing, initiates transfer. If already resizing, helps
1853 >     * perform transfer if work is available.  Rechecks occupancy
1854 >     * after a transfer to see if another resize is already needed
1855 >     * because resizings are lagging additions.
1856 >     *
1857 >     * @param x the count to add
1858 >     * @param check if <0, don't check resize, if <= 1 only check if uncontended
1859 >     */
1860 >    private final void addCount(long x, int check) {
1861 >        Cell[] as; long b, s;
1862 >        if ((as = counterCells) != null ||
1863 >            !U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
1864 >            Cell a; long v; int m;
1865 >            boolean uncontended = true;
1866 >            if (as == null || (m = as.length - 1) < 0 ||
1867 >                (a = as[ThreadLocalRandom.getProbe() & m]) == null ||
1868 >                !(uncontended =
1869 >                  U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
1870 >                fullAddCount(x, uncontended);
1871 >                return;
1872 >            }
1873 >            if (check <= 1)
1874 >                return;
1875 >            s = sumCount();
1876 >        }
1877 >        if (check >= 0) {
1878 >            Node<V>[] tab, nt; int sc;
1879 >            while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
1880 >                   tab.length < MAXIMUM_CAPACITY) {
1881 >                if (sc < 0) {
1882 >                    if (sc == -1 || transferIndex <= transferOrigin ||
1883 >                        (nt = nextTable) == null)
1884                          break;
1885 <                    e = e.next;
1885 >                    if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
1886 >                        transfer(tab, nt);
1887                  }
1888 +                else if (U.compareAndSwapInt(this, SIZECTL, sc, -2))
1889 +                    transfer(tab, null);
1890 +                s = sumCount();
1891 +            }
1892 +        }
1893 +    }
1894  
1895 <                V oldValue = e.value;
1896 <                if (value != null && !value.equals(oldValue))
1897 <                    return null;
1898 <
1899 <                // All entries following removed node can stay in list, but
1900 <                // all preceeding ones need to be cloned.
1901 <                HashEntry<K,V> newFirst = e.next;
1902 <                for (HashEntry<K,V> p = first; p != e; p = p.next)
1903 <                    newFirst = new HashEntry<K,V>(p.hash, p.key,
1904 <                                                  p.value, newFirst);
1905 <                tab[index] = newFirst;
1906 <                ++modCount;
1907 <                count = c-1; // write-volatile
1908 <                return oldValue;
1909 <            } finally {
1910 <                unlock();
1895 >    /**
1896 >     * Tries to presize table to accommodate the given number of elements.
1897 >     *
1898 >     * @param size number of elements (doesn't need to be perfectly accurate)
1899 >     */
1900 >    @SuppressWarnings("unchecked") private final void tryPresize(int size) {
1901 >        int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1902 >            tableSizeFor(size + (size >>> 1) + 1);
1903 >        int sc;
1904 >        while ((sc = sizeCtl) >= 0) {
1905 >            Node<V>[] tab = table; int n;
1906 >            if (tab == null || (n = tab.length) == 0) {
1907 >                n = (sc > c) ? sc : c;
1908 >                if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
1909 >                    try {
1910 >                        if (table == tab) {
1911 >                            @SuppressWarnings("rawtypes") Node[] tb = new Node[n];
1912 >                            table = (Node<V>[])tb;
1913 >                            sc = n - (n >>> 2);
1914 >                        }
1915 >                    } finally {
1916 >                        sizeCtl = sc;
1917 >                    }
1918 >                }
1919              }
1920 +            else if (c <= sc || n >= MAXIMUM_CAPACITY)
1921 +                break;
1922 +            else if (tab == table &&
1923 +                     U.compareAndSwapInt(this, SIZECTL, sc, -2))
1924 +                transfer(tab, null);
1925          }
1926 +    }
1927  
1928 <        void clear() {
1929 <            lock();
1928 >    /**
1929 >     * Moves and/or copies the nodes in each bin to new table. See
1930 >     * above for explanation.
1931 >     */
1932 >    @SuppressWarnings("unchecked") private final void transfer
1933 >        (Node<V>[] tab, Node<V>[] nextTab) {
1934 >        int n = tab.length, stride;
1935 >        if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
1936 >            stride = MIN_TRANSFER_STRIDE; // subdivide range
1937 >        if (nextTab == null) {            // initiating
1938              try {
1939 <                HashEntry[] tab = table;
1940 <                for (int i = 0; i < tab.length ; i++)
1941 <                    tab[i] = null;
1942 <                ++modCount;
1943 <                count = 0; // write-volatile
1944 <            } finally {
1945 <                unlock();
1939 >                @SuppressWarnings("rawtypes") Node[] tb = new Node[n << 1];
1940 >                nextTab = (Node<V>[])tb;
1941 >            } catch (Throwable ex) {      // try to cope with OOME
1942 >                sizeCtl = Integer.MAX_VALUE;
1943 >                return;
1944 >            }
1945 >            nextTable = nextTab;
1946 >            transferOrigin = n;
1947 >            transferIndex = n;
1948 >            Node<V> rev = new Node<V>(MOVED, tab, null, null);
1949 >            for (int k = n; k > 0;) {    // progressively reveal ready slots
1950 >                int nextk = (k > stride) ? k - stride : 0;
1951 >                for (int m = nextk; m < k; ++m)
1952 >                    nextTab[m] = rev;
1953 >                for (int m = n + nextk; m < n + k; ++m)
1954 >                    nextTab[m] = rev;
1955 >                U.putOrderedInt(this, TRANSFERORIGIN, k = nextk);
1956 >            }
1957 >        }
1958 >        int nextn = nextTab.length;
1959 >        Node<V> fwd = new Node<V>(MOVED, nextTab, null, null);
1960 >        boolean advance = true;
1961 >        for (int i = 0, bound = 0;;) {
1962 >            int nextIndex, nextBound; Node<V> f; Object fk;
1963 >            while (advance) {
1964 >                if (--i >= bound)
1965 >                    advance = false;
1966 >                else if ((nextIndex = transferIndex) <= transferOrigin) {
1967 >                    i = -1;
1968 >                    advance = false;
1969 >                }
1970 >                else if (U.compareAndSwapInt
1971 >                         (this, TRANSFERINDEX, nextIndex,
1972 >                          nextBound = (nextIndex > stride ?
1973 >                                       nextIndex - stride : 0))) {
1974 >                    bound = nextBound;
1975 >                    i = nextIndex - 1;
1976 >                    advance = false;
1977 >                }
1978 >            }
1979 >            if (i < 0 || i >= n || i + n >= nextn) {
1980 >                for (int sc;;) {
1981 >                    if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) {
1982 >                        if (sc == -1) {
1983 >                            nextTable = null;
1984 >                            table = nextTab;
1985 >                            sizeCtl = (n << 1) - (n >>> 1);
1986 >                        }
1987 >                        return;
1988 >                    }
1989 >                }
1990 >            }
1991 >            else if ((f = tabAt(tab, i)) == null) {
1992 >                if (casTabAt(tab, i, null, fwd)) {
1993 >                    setTabAt(nextTab, i, null);
1994 >                    setTabAt(nextTab, i + n, null);
1995 >                    advance = true;
1996 >                }
1997 >            }
1998 >            else if (f.hash >= 0) {
1999 >                synchronized (f) {
2000 >                    if (tabAt(tab, i) == f) {
2001 >                        int runBit = f.hash & n;
2002 >                        Node<V> lastRun = f, lo = null, hi = null;
2003 >                        for (Node<V> p = f.next; p != null; p = p.next) {
2004 >                            int b = p.hash & n;
2005 >                            if (b != runBit) {
2006 >                                runBit = b;
2007 >                                lastRun = p;
2008 >                            }
2009 >                        }
2010 >                        if (runBit == 0)
2011 >                            lo = lastRun;
2012 >                        else
2013 >                            hi = lastRun;
2014 >                        for (Node<V> p = f; p != lastRun; p = p.next) {
2015 >                            int ph = p.hash;
2016 >                            Object pk = p.key; V pv = p.val;
2017 >                            if ((ph & n) == 0)
2018 >                                lo = new Node<V>(ph, pk, pv, lo);
2019 >                            else
2020 >                                hi = new Node<V>(ph, pk, pv, hi);
2021 >                        }
2022 >                        setTabAt(nextTab, i, lo);
2023 >                        setTabAt(nextTab, i + n, hi);
2024 >                        setTabAt(tab, i, fwd);
2025 >                        advance = true;
2026 >                    }
2027 >                }
2028 >            }
2029 >            else if ((fk = f.key) instanceof TreeBin) {
2030 >                TreeBin<V> t = (TreeBin<V>)fk;
2031 >                t.acquire(0);
2032 >                try {
2033 >                    if (tabAt(tab, i) == f) {
2034 >                        TreeBin<V> lt = new TreeBin<V>();
2035 >                        TreeBin<V> ht = new TreeBin<V>();
2036 >                        int lc = 0, hc = 0;
2037 >                        for (Node<V> e = t.first; e != null; e = e.next) {
2038 >                            int h = e.hash;
2039 >                            Object k = e.key; V v = e.val;
2040 >                            if ((h & n) == 0) {
2041 >                                ++lc;
2042 >                                lt.putTreeNode(h, k, v);
2043 >                            }
2044 >                            else {
2045 >                                ++hc;
2046 >                                ht.putTreeNode(h, k, v);
2047 >                            }
2048 >                        }
2049 >                        Node<V> ln, hn; // throw away trees if too small
2050 >                        if (lc < TREE_THRESHOLD) {
2051 >                            ln = null;
2052 >                            for (Node<V> p = lt.first; p != null; p = p.next)
2053 >                                ln = new Node<V>(p.hash, p.key, p.val, ln);
2054 >                        }
2055 >                        else
2056 >                            ln = new Node<V>(MOVED, lt, null, null);
2057 >                        setTabAt(nextTab, i, ln);
2058 >                        if (hc < TREE_THRESHOLD) {
2059 >                            hn = null;
2060 >                            for (Node<V> p = ht.first; p != null; p = p.next)
2061 >                                hn = new Node<V>(p.hash, p.key, p.val, hn);
2062 >                        }
2063 >                        else
2064 >                            hn = new Node<V>(MOVED, ht, null, null);
2065 >                        setTabAt(nextTab, i + n, hn);
2066 >                        setTabAt(tab, i, fwd);
2067 >                        advance = true;
2068 >                    }
2069 >                } finally {
2070 >                    t.release(0);
2071 >                }
2072              }
2073 +            else
2074 +                advance = true; // already processed
2075          }
2076      }
2077  
2078 +    /* ---------------- Counter support -------------- */
2079 +
2080 +    final long sumCount() {
2081 +        Cell[] as = counterCells; Cell a;
2082 +        long sum = baseCount;
2083 +        if (as != null) {
2084 +            for (int i = 0; i < as.length; ++i) {
2085 +                if ((a = as[i]) != null)
2086 +                    sum += a.value;
2087 +            }
2088 +        }
2089 +        return sum;
2090 +    }
2091 +
2092 +    // See LongAdder version for explanation
2093 +    private final void fullAddCount(long x, boolean wasUncontended) {
2094 +        int h;
2095 +        if ((h = ThreadLocalRandom.getProbe()) == 0) {
2096 +            ThreadLocalRandom.localInit();      // force initialization
2097 +            h = ThreadLocalRandom.getProbe();
2098 +            wasUncontended = true;
2099 +        }
2100 +        boolean collide = false;                // True if last slot nonempty
2101 +        for (;;) {
2102 +            Cell[] as; Cell a; int n; long v;
2103 +            if ((as = counterCells) != null && (n = as.length) > 0) {
2104 +                if ((a = as[(n - 1) & h]) == null) {
2105 +                    if (cellsBusy == 0) {            // Try to attach new Cell
2106 +                        Cell r = new Cell(x); // Optimistic create
2107 +                        if (cellsBusy == 0 &&
2108 +                            U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2109 +                            boolean created = false;
2110 +                            try {               // Recheck under lock
2111 +                                Cell[] rs; int m, j;
2112 +                                if ((rs = counterCells) != null &&
2113 +                                    (m = rs.length) > 0 &&
2114 +                                    rs[j = (m - 1) & h] == null) {
2115 +                                    rs[j] = r;
2116 +                                    created = true;
2117 +                                }
2118 +                            } finally {
2119 +                                cellsBusy = 0;
2120 +                            }
2121 +                            if (created)
2122 +                                break;
2123 +                            continue;           // Slot is now non-empty
2124 +                        }
2125 +                    }
2126 +                    collide = false;
2127 +                }
2128 +                else if (!wasUncontended)       // CAS already known to fail
2129 +                    wasUncontended = true;      // Continue after rehash
2130 +                else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
2131 +                    break;
2132 +                else if (counterCells != as || n >= NCPU)
2133 +                    collide = false;            // At max size or stale
2134 +                else if (!collide)
2135 +                    collide = true;
2136 +                else if (cellsBusy == 0 &&
2137 +                         U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2138 +                    try {
2139 +                        if (counterCells == as) {// Expand table unless stale
2140 +                            Cell[] rs = new Cell[n << 1];
2141 +                            for (int i = 0; i < n; ++i)
2142 +                                rs[i] = as[i];
2143 +                            counterCells = rs;
2144 +                        }
2145 +                    } finally {
2146 +                        cellsBusy = 0;
2147 +                    }
2148 +                    collide = false;
2149 +                    continue;                   // Retry with expanded table
2150 +                }
2151 +                h = ThreadLocalRandom.advanceProbe(h);
2152 +            }
2153 +            else if (cellsBusy == 0 && counterCells == as &&
2154 +                     U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2155 +                boolean init = false;
2156 +                try {                           // Initialize table
2157 +                    if (counterCells == as) {
2158 +                        Cell[] rs = new Cell[2];
2159 +                        rs[h & 1] = new Cell(x);
2160 +                        counterCells = rs;
2161 +                        init = true;
2162 +                    }
2163 +                } finally {
2164 +                    cellsBusy = 0;
2165 +                }
2166 +                if (init)
2167 +                    break;
2168 +            }
2169 +            else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
2170 +                break;                          // Fall back on using base
2171 +        }
2172 +    }
2173 +
2174 +    /* ----------------Table Traversal -------------- */
2175 +
2176      /**
2177 <     * ConcurrentHashMap list entry.
2177 >     * Encapsulates traversal for methods such as containsValue; also
2178 >     * serves as a base class for other iterators and bulk tasks.
2179 >     *
2180 >     * At each step, the iterator snapshots the key ("nextKey") and
2181 >     * value ("nextVal") of a valid node (i.e., one that, at point of
2182 >     * snapshot, has a non-null user value). Because val fields can
2183 >     * change (including to null, indicating deletion), field nextVal
2184 >     * might not be accurate at point of use, but still maintains the
2185 >     * weak consistency property of holding a value that was once
2186 >     * valid. To support iterator.remove, the nextKey field is not
2187 >     * updated (nulled out) when the iterator cannot advance.
2188 >     *
2189 >     * Exported iterators must track whether the iterator has advanced
2190 >     * (in hasNext vs next) (by setting/checking/nulling field
2191 >     * nextVal), and then extract key, value, or key-value pairs as
2192 >     * return values of next().
2193 >     *
2194 >     * Method advance visits once each still-valid node that was
2195 >     * reachable upon iterator construction. It might miss some that
2196 >     * were added to a bin after the bin was visited, which is OK wrt
2197 >     * consistency guarantees. Maintaining this property in the face
2198 >     * of possible ongoing resizes requires a fair amount of
2199 >     * bookkeeping state that is difficult to optimize away amidst
2200 >     * volatile accesses.  Even so, traversal maintains reasonable
2201 >     * throughput.
2202 >     *
2203 >     * Normally, iteration proceeds bin-by-bin traversing lists.
2204 >     * However, if the table has been resized, then all future steps
2205 >     * must traverse both the bin at the current index as well as at
2206 >     * (index + baseSize); and so on for further resizings. To
2207 >     * paranoically cope with potential sharing by users of iterators
2208 >     * across threads, iteration terminates if a bounds checks fails
2209 >     * for a table read.
2210 >     *
2211 >     * Methods advanceKey and advanceValue are specializations of the
2212 >     * common cases of advance, relaying to the full version
2213 >     * otherwise. The forEachKey and forEachValue methods further
2214 >     * specialize, bypassing all incremental field updates in most cases.
2215 >     *
2216 >     * This class supports both Spliterator-based traversal and
2217 >     * CountedCompleter-based bulk tasks. The same "batch" field is
2218 >     * used, but in slightly different ways, in the two cases.  For
2219 >     * Spliterators, it is a saturating (at Integer.MAX_VALUE)
2220 >     * estimate of element coverage. For CHM tasks, it is a pre-scaled
2221 >     * size that halves down to zero for leaf tasks, that is only
2222 >     * computed upon execution of the task. (Tasks can be submitted to
2223 >     * any pool, of any size, so we don't know scale factors until
2224 >     * running.)
2225 >     *
2226 >     * This class extends CountedCompleter to streamline parallel
2227 >     * iteration in bulk operations. This adds only a few fields of
2228 >     * space overhead, which is small enough in cases where it is not
2229 >     * needed to not worry about it.  Because CountedCompleter is
2230 >     * Serializable, but iterators need not be, we need to add warning
2231 >     * suppressions.
2232       */
2233 <    private static class HashEntry<K,V> implements Entry<K,V> {
2234 <        private final K key;
2235 <        private V value;
2236 <        private final int hash;
2237 <        private final HashEntry<K,V> next;
2233 >    @SuppressWarnings("serial") static class Traverser<K,V,R>
2234 >        extends CountedCompleter<R> {
2235 >        final ConcurrentHashMap<K,V> map;
2236 >        Node<V> next;        // the next entry to use
2237 >        K nextKey;           // cached key field of next
2238 >        V nextVal;           // cached val field of next
2239 >        Node<V>[] tab;       // current table; updated if resized
2240 >        int index;           // index of bin to use next
2241 >        int baseIndex;       // current index of initial table
2242 >        int baseLimit;       // index bound for initial table
2243 >        final int baseSize;  // initial table size
2244 >        int batch;           // split control
2245 >
2246 >        /** Creates iterator for all entries in the table. */
2247 >        Traverser(ConcurrentHashMap<K,V> map) {
2248 >            this.map = map;
2249 >            Node<V>[] t = this.tab = map.table;
2250 >            baseLimit = baseSize = (t == null) ? 0 : t.length;
2251 >        }
2252 >
2253 >        /** Task constructor */
2254 >        Traverser(ConcurrentHashMap<K,V> map, Traverser<K,V,?> it, int batch) {
2255 >            super(it);
2256 >            this.map = map;
2257 >            this.batch = batch; // -1 if unknown
2258 >            if (it == null) {
2259 >                Node<V>[] t = this.tab = map.table;
2260 >                baseLimit = baseSize = (t == null) ? 0 : t.length;
2261 >            }
2262 >            else { // split parent
2263 >                this.tab = it.tab;
2264 >                this.baseSize = it.baseSize;
2265 >                int hi = this.baseLimit = it.baseLimit;
2266 >                it.baseLimit = this.index = this.baseIndex =
2267 >                    (hi + it.baseIndex) >>> 1;
2268 >            }
2269 >        }
2270  
2271 <        HashEntry(int hash, K key, V value, HashEntry<K,V> next) {
2272 <            this.value = value;
2273 <            this.hash = hash;
2274 <            this.key = key;
2275 <            this.next = next;
2271 >        /** Spliterator constructor */
2272 >        Traverser(ConcurrentHashMap<K,V> map, Traverser<K,V,?> it) {
2273 >            super(it);
2274 >            this.map = map;
2275 >            if (it == null) {
2276 >                Node<V>[] t = this.tab = map.table;
2277 >                baseLimit = baseSize = (t == null) ? 0 : t.length;
2278 >                long n = map.sumCount();
2279 >                batch = ((n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
2280 >                         (int)n);
2281 >            }
2282 >            else {
2283 >                this.tab = it.tab;
2284 >                this.baseSize = it.baseSize;
2285 >                int hi = this.baseLimit = it.baseLimit;
2286 >                it.baseLimit = this.index = this.baseIndex =
2287 >                    (hi + it.baseIndex) >>> 1;
2288 >                this.batch = it.batch >>>= 1;
2289 >            }
2290          }
2291  
2292 <        public K getKey() {
2293 <            return key;
2292 >        /**
2293 >         * Advances if possible, returning next valid value, or null if none.
2294 >         */
2295 >        @SuppressWarnings("unchecked") final V advance() {
2296 >            for (Node<V> e = next;;) {
2297 >                if (e != null)                  // advance past used/skipped node
2298 >                    e = next = e.next;
2299 >                while (e == null) {             // get to next non-null bin
2300 >                    Node<V>[] t; int i, n;      // must use locals in checks
2301 >                    if (baseIndex >= baseLimit || (t = tab) == null ||
2302 >                        (n = t.length) <= (i = index) || i < 0)
2303 >                        return nextVal = null;
2304 >                    if ((e = next = tabAt(t, index)) != null && e.hash < 0) {
2305 >                        Object ek;
2306 >                        if ((ek = e.key) instanceof TreeBin)
2307 >                            e = ((TreeBin<V>)ek).first;
2308 >                        else {
2309 >                            tab = (Node<V>[])ek;
2310 >                            continue;           // restarts due to null val
2311 >                        }
2312 >                    }
2313 >                    if ((index += baseSize) >= n)
2314 >                        index = ++baseIndex;    // visit upper slots if present
2315 >                }
2316 >                nextKey = (K)e.key;
2317 >                if ((nextVal = e.val) != null) // skip deleted or special nodes
2318 >                    return nextVal;
2319 >            }
2320          }
2321  
2322 <        public V getValue() {
2323 <            return value;
2322 >        /**
2323 >         * Common case version for value traversal
2324 >         */
2325 >        @SuppressWarnings("unchecked") final V advanceValue() {
2326 >            outer: for (Node<V> e = next;;) {
2327 >                if (e == null || (e = e.next) == null) {
2328 >                    Node<V>[] t; int i, len, n; Object ek;
2329 >                    if ((t = tab) == null ||
2330 >                        baseSize != (len = t.length) ||
2331 >                        len < (n = baseLimit) ||
2332 >                        baseIndex != (i = index))
2333 >                        break;
2334 >                    do {
2335 >                        if (i < 0 || i >= n) {
2336 >                            index = baseIndex = n;
2337 >                            next = null;
2338 >                            return nextVal = null;
2339 >                        }
2340 >                        if ((e = tabAt(t, i)) != null && e.hash < 0) {
2341 >                            if ((ek = e.key) instanceof TreeBin)
2342 >                                e = ((TreeBin<V>)ek).first;
2343 >                            else {
2344 >                                index = baseIndex = i;
2345 >                                next = null;
2346 >                                tab = (Node<V>[])ek;
2347 >                                break outer;
2348 >                            }
2349 >                        }
2350 >                        ++i;
2351 >                    } while (e == null);
2352 >                    index = baseIndex = i;
2353 >                }
2354 >                V v;
2355 >                K k = (K)e.key;
2356 >                if ((v = e.val) != null) {
2357 >                    nextVal = v;
2358 >                    nextKey = k;
2359 >                    next = e;
2360 >                    return v;
2361 >                }
2362 >            }
2363 >            return advance();
2364          }
2365  
2366 <        public V setValue(V newValue) {
2367 <            // We aren't required to, and don't provide any
2368 <            // visibility barriers for setting value.
2369 <            if (newValue == null)
2370 <                throw new NullPointerException();
2371 <            V oldValue = this.value;
2372 <            this.value = newValue;
2373 <            return oldValue;
2366 >        /**
2367 >         * Common case version for key traversal
2368 >         */
2369 >        @SuppressWarnings("unchecked") final K advanceKey() {
2370 >            outer: for (Node<V> e = next;;) {
2371 >                if (e == null || (e = e.next) == null) {
2372 >                    Node<V>[] t; int i, len, n; Object ek;
2373 >                    if ((t = tab) == null ||
2374 >                        baseSize != (len = t.length) ||
2375 >                        len < (n = baseLimit) ||
2376 >                        baseIndex != (i = index))
2377 >                        break;
2378 >                    do {
2379 >                        if (i < 0 || i >= n) {
2380 >                            index = baseIndex = n;
2381 >                            next = null;
2382 >                            nextVal = null;
2383 >                            return null;
2384 >                        }
2385 >                        if ((e = tabAt(t, i)) != null && e.hash < 0) {
2386 >                            if ((ek = e.key) instanceof TreeBin)
2387 >                                e = ((TreeBin<V>)ek).first;
2388 >                            else {
2389 >                                index = baseIndex = i;
2390 >                                next = null;
2391 >                                tab = (Node<V>[])ek;
2392 >                                break outer;
2393 >                            }
2394 >                        }
2395 >                        ++i;
2396 >                    } while (e == null);
2397 >                    index = baseIndex = i;
2398 >                }
2399 >                V v;
2400 >                K k = (K)e.key;
2401 >                if ((v = e.val) != null) {
2402 >                    nextVal = v;
2403 >                    nextKey = k;
2404 >                    next = e;
2405 >                    return k;
2406 >                }
2407 >            }
2408 >            return (advance() == null) ? null : nextKey;
2409          }
2410  
2411 <        public boolean equals(Object o) {
2412 <            if (!(o instanceof Entry))
2413 <                return false;
2414 <            Entry<K,V> e = (Entry<K,V>)o;
2415 <            return (key.equals(e.getKey()) && value.equals(e.getValue()));
2411 >        @SuppressWarnings("unchecked") final void forEachValue(Consumer<? super V> action) {
2412 >            if (action == null) throw new NullPointerException();
2413 >            Node<V>[] t; int i, len, n;
2414 >            if ((t = tab) != null && baseSize == (len = t.length) &&
2415 >                len >= (n = baseLimit) && baseIndex == (i = index)) {
2416 >                index = baseIndex = n;
2417 >                nextVal = null;
2418 >                Node<V> e = next;
2419 >                next = null;
2420 >                if (e != null)
2421 >                    e = e.next;
2422 >                outer: for (;; e = e.next) {
2423 >                    V v; Object ek;
2424 >                    for (; e == null; ++i) {
2425 >                        if (i < 0 || i >= n)
2426 >                            return;
2427 >                        if ((e = tabAt(t, i)) != null && e.hash < 0) {
2428 >                            if ((ek = e.key) instanceof TreeBin)
2429 >                                e = ((TreeBin<V>)ek).first;
2430 >                            else {
2431 >                                index = baseIndex = i;
2432 >                                tab = (Node<V>[])ek;
2433 >                                break outer;
2434 >                            }
2435 >                        }
2436 >                    }
2437 >                    if ((v = e.val) != null)
2438 >                        action.accept(v);
2439 >                }
2440 >            }
2441 >            V v;
2442 >            while ((v = advance()) != null)
2443 >                action.accept(v);
2444          }
2445  
2446 <        public int hashCode() {
2447 <            return  key.hashCode() ^ value.hashCode();
2446 >        @SuppressWarnings("unchecked") final void forEachKey(Consumer<? super K> action) {
2447 >            if (action == null) throw new NullPointerException();
2448 >            Node<V>[] t; int i, len, n;
2449 >            if ((t = tab) != null && baseSize == (len = t.length) &&
2450 >                len >= (n = baseLimit) && baseIndex == (i = index)) {
2451 >                index = baseIndex = n;
2452 >                nextVal = null;
2453 >                Node<V> e = next;
2454 >                next = null;
2455 >                if (e != null)
2456 >                    e = e.next;
2457 >                outer: for (;; e = e.next) {
2458 >                    for (; e == null; ++i) {
2459 >                        if (i < 0 || i >= n)
2460 >                            return;
2461 >                        if ((e = tabAt(t, i)) != null && e.hash < 0) {
2462 >                            Object ek;
2463 >                            if ((ek = e.key) instanceof TreeBin)
2464 >                                e = ((TreeBin<V>)ek).first;
2465 >                            else {
2466 >                                index = baseIndex = i;
2467 >                                tab = (Node<V>[])ek;
2468 >                                break outer;
2469 >                            }
2470 >                        }
2471 >                    }
2472 >                    Object k = e.key;
2473 >                    if (e.val != null)
2474 >                        action.accept((K)k);
2475 >                }
2476 >            }
2477 >            while (advance() != null)
2478 >                action.accept(nextKey);
2479          }
2480  
2481 <        public String toString() {
2482 <            return key + "=" + value;
2481 >        public final void remove() {
2482 >            K k = nextKey;
2483 >            if (k == null && (advanceValue() == null || (k = nextKey) == null))
2484 >                throw new IllegalStateException();
2485 >            map.internalReplace(k, null, null);
2486          }
483    }
2487  
2488 +        public final boolean hasNext() {
2489 +            return nextVal != null || advanceValue() != null;
2490 +        }
2491 +
2492 +        public final boolean hasMoreElements() { return hasNext(); }
2493 +
2494 +        public void compute() { } // default no-op CountedCompleter body
2495 +
2496 +        public long estimateSize() { return batch; }
2497 +
2498 +        /**
2499 +         * Returns a batch value > 0 if this task should (and must) be
2500 +         * split, if so, adding to pending count, and in any case
2501 +         * updating batch value. The initial batch value is approx
2502 +         * exp2 of the number of times (minus one) to split task by
2503 +         * two before executing leaf action. This value is faster to
2504 +         * compute and more convenient to use as a guide to splitting
2505 +         * than is the depth, since it is used while dividing by two
2506 +         * anyway.
2507 +         */
2508 +        final int preSplit() {
2509 +            int b;  ForkJoinPool pool;
2510 +            if ((b = batch) < 0) { // force initialization
2511 +                int sp = (((pool = getPool()) == null) ?
2512 +                          ForkJoinPool.getCommonPoolParallelism() :
2513 +                          pool.getParallelism()) << 3; // slack of 8
2514 +                long n = map.sumCount();
2515 +                b = (n <= 0L) ? 0 : (n < (long)sp) ? (int)n : sp;
2516 +            }
2517 +            b = (b <= 1 || baseIndex >= baseLimit) ? 0 : (b >>> 1);
2518 +            if ((batch = b) > 0)
2519 +                addToPendingCount(1);
2520 +            return b;
2521 +        }
2522 +    }
2523  
2524      /* ---------------- Public operations -------------- */
2525  
2526      /**
2527 <     * Constructs a new, empty map with the specified initial
2528 <     * capacity and the specified load factor.
2527 >     * Creates a new, empty map with the default initial table size (16).
2528 >     */
2529 >    public ConcurrentHashMap() {
2530 >    }
2531 >
2532 >    /**
2533 >     * Creates a new, empty map with an initial table size
2534 >     * accommodating the specified number of elements without the need
2535 >     * to dynamically resize.
2536 >     *
2537 >     * @param initialCapacity The implementation performs internal
2538 >     * sizing to accommodate this many elements.
2539 >     * @throws IllegalArgumentException if the initial capacity of
2540 >     * elements is negative
2541 >     */
2542 >    public ConcurrentHashMap(int initialCapacity) {
2543 >        if (initialCapacity < 0)
2544 >            throw new IllegalArgumentException();
2545 >        int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
2546 >                   MAXIMUM_CAPACITY :
2547 >                   tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
2548 >        this.sizeCtl = cap;
2549 >    }
2550 >
2551 >    /**
2552 >     * Creates a new map with the same mappings as the given map.
2553 >     *
2554 >     * @param m the map
2555 >     */
2556 >    public ConcurrentHashMap(Map<? extends K, ? extends V> m) {
2557 >        this.sizeCtl = DEFAULT_CAPACITY;
2558 >        internalPutAll(m);
2559 >    }
2560 >
2561 >    /**
2562 >     * Creates a new, empty map with an initial table size based on
2563 >     * the given number of elements ({@code initialCapacity}) and
2564 >     * initial table density ({@code loadFactor}).
2565       *
2566       * @param initialCapacity the initial capacity. The implementation
2567 <     * performs internal sizing to accommodate this many elements.
2568 <     * @param loadFactor  the load factor threshold, used to control resizing.
2567 >     * performs internal sizing to accommodate this many elements,
2568 >     * given the specified load factor.
2569 >     * @param loadFactor the load factor (table density) for
2570 >     * establishing the initial table size
2571 >     * @throws IllegalArgumentException if the initial capacity of
2572 >     * elements is negative or the load factor is nonpositive
2573 >     *
2574 >     * @since 1.6
2575 >     */
2576 >    public ConcurrentHashMap(int initialCapacity, float loadFactor) {
2577 >        this(initialCapacity, loadFactor, 1);
2578 >    }
2579 >
2580 >    /**
2581 >     * Creates a new, empty map with an initial table size based on
2582 >     * the given number of elements ({@code initialCapacity}), table
2583 >     * density ({@code loadFactor}), and number of concurrently
2584 >     * updating threads ({@code concurrencyLevel}).
2585 >     *
2586 >     * @param initialCapacity the initial capacity. The implementation
2587 >     * performs internal sizing to accommodate this many elements,
2588 >     * given the specified load factor.
2589 >     * @param loadFactor the load factor (table density) for
2590 >     * establishing the initial table size
2591       * @param concurrencyLevel the estimated number of concurrently
2592 <     * updating threads. The implementation performs internal sizing
2593 <     * to try to accommodate this many threads.  
2592 >     * updating threads. The implementation may use this value as
2593 >     * a sizing hint.
2594       * @throws IllegalArgumentException if the initial capacity is
2595       * negative or the load factor or concurrencyLevel are
2596 <     * nonpositive.
2596 >     * nonpositive
2597       */
2598      public ConcurrentHashMap(int initialCapacity,
2599 <                             float loadFactor, int concurrencyLevel) {
2600 <        if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
2599 >                               float loadFactor, int concurrencyLevel) {
2600 >        if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
2601              throw new IllegalArgumentException();
2602 +        if (initialCapacity < concurrencyLevel)   // Use at least as many bins
2603 +            initialCapacity = concurrencyLevel;   // as estimated threads
2604 +        long size = (long)(1.0 + (long)initialCapacity / loadFactor);
2605 +        int cap = (size >= (long)MAXIMUM_CAPACITY) ?
2606 +            MAXIMUM_CAPACITY : tableSizeFor((int)size);
2607 +        this.sizeCtl = cap;
2608 +    }
2609  
2610 <        if (concurrencyLevel > MAX_SEGMENTS)
2611 <            concurrencyLevel = MAX_SEGMENTS;
2612 <
2613 <        // Find power-of-two sizes best matching arguments
2614 <        int sshift = 0;
2615 <        int ssize = 1;
2616 <        while (ssize < concurrencyLevel) {
2617 <            ++sshift;
2618 <            ssize <<= 1;
516 <        }
517 <        segmentShift = 32 - sshift;
518 <        segmentMask = ssize - 1;
519 <        this.segments = new Segment[ssize];
520 <
521 <        if (initialCapacity > MAXIMUM_CAPACITY)
522 <            initialCapacity = MAXIMUM_CAPACITY;
523 <        int c = initialCapacity / ssize;
524 <        if (c * ssize < initialCapacity)
525 <            ++c;
526 <        int cap = 1;
527 <        while (cap < c)
528 <            cap <<= 1;
529 <
530 <        for (int i = 0; i < this.segments.length; ++i)
531 <            this.segments[i] = new Segment<K,V>(cap, loadFactor);
2610 >    /**
2611 >     * Creates a new {@link Set} backed by a ConcurrentHashMap
2612 >     * from the given type to {@code Boolean.TRUE}.
2613 >     *
2614 >     * @return the new set
2615 >     */
2616 >    public static <K> KeySetView<K,Boolean> newKeySet() {
2617 >        return new KeySetView<K,Boolean>
2618 >            (new ConcurrentHashMap<K,Boolean>(), Boolean.TRUE);
2619      }
2620  
2621      /**
2622 <     * Constructs a new, empty map with the specified initial
2623 <     * capacity,  and with default load factor and concurrencyLevel.
2622 >     * Creates a new {@link Set} backed by a ConcurrentHashMap
2623 >     * from the given type to {@code Boolean.TRUE}.
2624       *
2625       * @param initialCapacity The implementation performs internal
2626       * sizing to accommodate this many elements.
2627       * @throws IllegalArgumentException if the initial capacity of
2628 <     * elements is negative.
2628 >     * elements is negative
2629 >     * @return the new set
2630       */
2631 <    public ConcurrentHashMap(int initialCapacity) {
2632 <        this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2631 >    public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
2632 >        return new KeySetView<K,Boolean>
2633 >            (new ConcurrentHashMap<K,Boolean>(initialCapacity), Boolean.TRUE);
2634      }
2635  
2636      /**
2637 <     * Constructs a new, empty map with a default initial capacity,
549 <     * load factor, and concurrencyLevel.
2637 >     * {@inheritDoc}
2638       */
2639 <    public ConcurrentHashMap() {
2640 <        this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2639 >    public boolean isEmpty() {
2640 >        return sumCount() <= 0L; // ignore transient negative values
2641      }
2642  
2643      /**
2644 <     * Constructs a new map with the same mappings as the given map.  The
557 <     * map is created with a capacity of twice the number of mappings in
558 <     * the given map or 11 (whichever is greater), and a default load factor.
2644 >     * {@inheritDoc}
2645       */
2646 <    public <A extends K, B extends V> ConcurrentHashMap(Map<A,B> t) {
2647 <        this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1,
2648 <                      11),
2649 <             DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2650 <        putAll(t);
2646 >    public int size() {
2647 >        long n = sumCount();
2648 >        return ((n < 0L) ? 0 :
2649 >                (n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
2650 >                (int)n);
2651      }
2652  
2653 <    // inherit Map javadoc
2654 <    public boolean isEmpty() {
2655 <        /*
2656 <         * We need to keep track of per-segment modCounts to avoid ABA
2657 <         * problems in which an element in one segment was added and
2658 <         * in another removed during traversal, in which case the
2659 <         * table was never actually empty at any point. Note the
2660 <         * similar use of modCounts in the size() and containsValue()
2661 <         * methods, which are the only other methods also susceptible
2662 <         * to ABA problems.
2663 <         */
2664 <        int[] mc = new int[segments.length];
579 <        int mcsum = 0;
580 <        for (int i = 0; i < segments.length; ++i) {
581 <            if (segments[i].count != 0)
582 <                return false;
583 <            else
584 <                mcsum += mc[i] = segments[i].modCount;
585 <        }
586 <        // If mcsum happens to be zero, then we know we got a snapshot
587 <        // before any modifications at all were made.  This is
588 <        // probably common enough to bother tracking.
589 <        if (mcsum != 0) {
590 <            for (int i = 0; i < segments.length; ++i) {
591 <                if (segments[i].count != 0 ||
592 <                    mc[i] != segments[i].modCount)
593 <                    return false;
594 <            }
595 <        }
596 <        return true;
2653 >    /**
2654 >     * Returns the number of mappings. This method should be used
2655 >     * instead of {@link #size} because a ConcurrentHashMap may
2656 >     * contain more mappings than can be represented as an int. The
2657 >     * value returned is an estimate; the actual count may differ if
2658 >     * there are concurrent insertions or removals.
2659 >     *
2660 >     * @return the number of mappings
2661 >     */
2662 >    public long mappingCount() {
2663 >        long n = sumCount();
2664 >        return (n < 0L) ? 0L : n; // ignore transient negative values
2665      }
2666  
2667 <    // inherit Map javadoc
2668 <    public int size() {
2669 <        int[] mc = new int[segments.length];
2670 <        for (;;) {
2671 <            long sum = 0;
2672 <            int mcsum = 0;
2673 <            for (int i = 0; i < segments.length; ++i) {
2674 <                sum += segments[i].count;
2675 <                mcsum += mc[i] = segments[i].modCount;
2676 <            }
2677 <            int check = 0;
2678 <            if (mcsum != 0) {
2679 <                for (int i = 0; i < segments.length; ++i) {
612 <                    check += segments[i].count;
613 <                    if (mc[i] != segments[i].modCount) {
614 <                        check = -1; // force retry
615 <                        break;
616 <                    }
617 <                }
618 <            }
619 <            if (check == sum) {
620 <                if (sum > Integer.MAX_VALUE)
621 <                    return Integer.MAX_VALUE;
622 <                else
623 <                    return (int)sum;
624 <            }
625 <        }
2667 >    /**
2668 >     * Returns the value to which the specified key is mapped,
2669 >     * or {@code null} if this map contains no mapping for the key.
2670 >     *
2671 >     * <p>More formally, if this map contains a mapping from a key
2672 >     * {@code k} to a value {@code v} such that {@code key.equals(k)},
2673 >     * then this method returns {@code v}; otherwise it returns
2674 >     * {@code null}.  (There can be at most one such mapping.)
2675 >     *
2676 >     * @throws NullPointerException if the specified key is null
2677 >     */
2678 >    public V get(Object key) {
2679 >        return internalGet(key);
2680      }
2681  
628
2682      /**
2683 <     * Returns the value to which the specified key is mapped in this table.
2683 >     * Returns the value to which the specified key is mapped,
2684 >     * or the given defaultValue if this map contains no mapping for the key.
2685       *
2686 <     * @param   key   a key in the table.
2687 <     * @return  the value to which the key is mapped in this table;
2688 <     *          <tt>null</tt> if the key is not mapped to any value in
2689 <     *          this table.
2690 <     * @throws  NullPointerException  if the key is
637 <     *               <tt>null</tt>.
2686 >     * @param key the key
2687 >     * @param defaultValue the value to return if this map contains
2688 >     * no mapping for the given key
2689 >     * @return the mapping for the key, if present; else the defaultValue
2690 >     * @throws NullPointerException if the specified key is null
2691       */
2692 <    public V get(Object key) {
2693 <        int hash = hash(key); // throws NullPointerException if key null
2694 <        return segmentFor(hash).get((K) key, hash);
2692 >    public V getOrDefault(Object key, V defaultValue) {
2693 >        V v;
2694 >        return (v = internalGet(key)) == null ? defaultValue : v;
2695      }
2696  
2697      /**
2698       * Tests if the specified object is a key in this table.
2699       *
2700 <     * @param   key   possible key.
2701 <     * @return  <tt>true</tt> if and only if the specified object
2702 <     *          is a key in this table, as determined by the
2703 <     *          <tt>equals</tt> method; <tt>false</tt> otherwise.
2704 <     * @throws  NullPointerException  if the key is
652 <     *               <tt>null</tt>.
2700 >     * @param  key possible key
2701 >     * @return {@code true} if and only if the specified object
2702 >     *         is a key in this table, as determined by the
2703 >     *         {@code equals} method; {@code false} otherwise
2704 >     * @throws NullPointerException if the specified key is null
2705       */
2706      public boolean containsKey(Object key) {
2707 <        int hash = hash(key); // throws NullPointerException if key null
656 <        return segmentFor(hash).containsKey(key, hash);
2707 >        return internalGet(key) != null;
2708      }
2709  
2710      /**
2711 <     * Returns <tt>true</tt> if this map maps one or more keys to the
2712 <     * specified value. Note: This method requires a full internal
2713 <     * traversal of the hash table, and so is much slower than
663 <     * method <tt>containsKey</tt>.
2711 >     * Returns {@code true} if this map maps one or more keys to the
2712 >     * specified value. Note: This method may require a full traversal
2713 >     * of the map, and is much slower than method {@code containsKey}.
2714       *
2715 <     * @param value value whose presence in this map is to be tested.
2716 <     * @return <tt>true</tt> if this map maps one or more keys to the
2717 <     * specified value.
2718 <     * @throws  NullPointerException  if the value is <tt>null</tt>.
2715 >     * @param value value whose presence in this map is to be tested
2716 >     * @return {@code true} if this map maps one or more keys to the
2717 >     *         specified value
2718 >     * @throws NullPointerException if the specified value is null
2719       */
2720      public boolean containsValue(Object value) {
2721          if (value == null)
2722              throw new NullPointerException();
2723 <
2724 <        int[] mc = new int[segments.length];
2725 <        for (;;) {
2726 <            int sum = 0;
2727 <            int mcsum = 0;
678 <            for (int i = 0; i < segments.length; ++i) {
679 <                int c = segments[i].count;
680 <                mcsum += mc[i] = segments[i].modCount;
681 <                if (segments[i].containsValue(value))
682 <                    return true;
683 <            }
684 <            boolean cleanSweep = true;
685 <            if (mcsum != 0) {
686 <                for (int i = 0; i < segments.length; ++i) {
687 <                    int c = segments[i].count;
688 <                    if (mc[i] != segments[i].modCount) {
689 <                        cleanSweep = false;
690 <                        break;
691 <                    }
692 <                }
693 <            }
694 <            if (cleanSweep)
695 <                return false;
2723 >        V v;
2724 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
2725 >        while ((v = it.advanceValue()) != null) {
2726 >            if (v == value || value.equals(v))
2727 >                return true;
2728          }
2729 +        return false;
2730      }
2731  
2732      /**
2733       * Legacy method testing if some key maps into the specified value
2734       * in this table.  This method is identical in functionality to
2735 <     * {@link #containsValue}, and  exists solely to ensure
2735 >     * {@link #containsValue(Object)}, and exists solely to ensure
2736       * full compatibility with class {@link java.util.Hashtable},
2737       * which supported this method prior to introduction of the
2738       * Java Collections framework.
2739 <
2740 <     * @param      value   a value to search for.
2741 <     * @return     <tt>true</tt> if and only if some key maps to the
2742 <     *             <tt>value</tt> argument in this table as
2743 <     *             determined by the <tt>equals</tt> method;
2744 <     *             <tt>false</tt> otherwise.
2745 <     * @throws  NullPointerException  if the value is <tt>null</tt>.
2739 >     *
2740 >     * @param  value a value to search for
2741 >     * @return {@code true} if and only if some key maps to the
2742 >     *         {@code value} argument in this table as
2743 >     *         determined by the {@code equals} method;
2744 >     *         {@code false} otherwise
2745 >     * @throws NullPointerException if the specified value is null
2746       */
2747 <    public boolean contains(Object value) {
2747 >    @Deprecated public boolean contains(Object value) {
2748          return containsValue(value);
2749      }
2750  
2751      /**
2752 <     * Maps the specified <tt>key</tt> to the specified
2753 <     * <tt>value</tt> in this table. Neither the key nor the
721 <     * value can be <tt>null</tt>. <p>
2752 >     * Maps the specified key to the specified value in this table.
2753 >     * Neither the key nor the value can be null.
2754       *
2755 <     * The value can be retrieved by calling the <tt>get</tt> method
2755 >     * <p>The value can be retrieved by calling the {@code get} method
2756       * with a key that is equal to the original key.
2757       *
2758 <     * @param      key     the table key.
2759 <     * @param      value   the value.
2760 <     * @return     the previous value of the specified key in this table,
2761 <     *             or <tt>null</tt> if it did not have one.
2762 <     * @throws  NullPointerException  if the key or value is
731 <     *               <tt>null</tt>.
2758 >     * @param key key with which the specified value is to be associated
2759 >     * @param value value to be associated with the specified key
2760 >     * @return the previous value associated with {@code key}, or
2761 >     *         {@code null} if there was no mapping for {@code key}
2762 >     * @throws NullPointerException if the specified key or value is null
2763       */
2764      public V put(K key, V value) {
2765 <        if (value == null)
735 <            throw new NullPointerException();
736 <        int hash = hash(key);
737 <        return segmentFor(hash).put(key, hash, value, false);
2765 >        return internalPut(key, value, false);
2766      }
2767  
2768      /**
2769 <     * If the specified key is not already associated
742 <     * with a value, associate it with the given value.
743 <     * This is equivalent to
744 <     * <pre>
745 <     *   if (!map.containsKey(key))
746 <     *      return map.put(key, value);
747 <     *   else
748 <     *      return map.get(key);
749 <     * </pre>
750 <     * Except that the action is performed atomically.
751 <     * @param key key with which the specified value is to be associated.
752 <     * @param value value to be associated with the specified key.
753 <     * @return previous value associated with specified key, or <tt>null</tt>
754 <     *         if there was no mapping for key.  A <tt>null</tt> return can
755 <     *         also indicate that the map previously associated <tt>null</tt>
756 <     *         with the specified key, if the implementation supports
757 <     *         <tt>null</tt> values.
758 <     *
759 <     * @throws UnsupportedOperationException if the <tt>put</tt> operation is
760 <     *            not supported by this map.
761 <     * @throws ClassCastException if the class of the specified key or value
762 <     *            prevents it from being stored in this map.
763 <     * @throws NullPointerException if the specified key or value is
764 <     *            <tt>null</tt>.
2769 >     * {@inheritDoc}
2770       *
2771 <     **/
2771 >     * @return the previous value associated with the specified key,
2772 >     *         or {@code null} if there was no mapping for the key
2773 >     * @throws NullPointerException if the specified key or value is null
2774 >     */
2775      public V putIfAbsent(K key, V value) {
2776 <        if (value == null)
769 <            throw new NullPointerException();
770 <        int hash = hash(key);
771 <        return segmentFor(hash).put(key, hash, value, true);
2776 >        return internalPut(key, value, true);
2777      }
2778  
774
2779      /**
2780       * Copies all of the mappings from the specified map to this one.
777     *
2781       * These mappings replace any mappings that this map had for any of the
2782 <     * keys currently in the specified Map.
2782 >     * keys currently in the specified map.
2783       *
2784 <     * @param t Mappings to be stored in this map.
2784 >     * @param m mappings to be stored in this map
2785       */
2786 <    public void putAll(Map<? extends K, ? extends V> t) {
2787 <        for (Iterator<Map.Entry<? extends K, ? extends V>> it = (Iterator<Map.Entry<? extends K, ? extends V>>) t.entrySet().iterator(); it.hasNext(); ) {
785 <            Entry<? extends K, ? extends V> e = it.next();
786 <            put(e.getKey(), e.getValue());
787 <        }
2786 >    public void putAll(Map<? extends K, ? extends V> m) {
2787 >        internalPutAll(m);
2788      }
2789  
2790      /**
2791 <     * Removes the key (and its corresponding value) from this
2792 <     * table. This method does nothing if the key is not in the table.
2791 >     * If the specified key is not already associated with a value (or
2792 >     * is mapped to {@code null}), attempts to compute its value using
2793 >     * the given mapping function and enters it into this map unless
2794 >     * {@code null}. The entire method invocation is performed
2795 >     * atomically, so the function is applied at most once per key.
2796 >     * Some attempted update operations on this map by other threads
2797 >     * may be blocked while computation is in progress, so the
2798 >     * computation should be short and simple, and must not attempt to
2799 >     * update any other mappings of this Map.
2800       *
2801 <     * @param   key   the key that needs to be removed.
2802 <     * @return  the value to which the key had been mapped in this table,
2803 <     *          or <tt>null</tt> if the key did not have a mapping.
2804 <     * @throws  NullPointerException  if the key is
2805 <     *               <tt>null</tt>.
2801 >     * @param key key with which the specified value is to be associated
2802 >     * @param mappingFunction the function to compute a value
2803 >     * @return the current (existing or computed) value associated with
2804 >     *         the specified key, or null if the computed value is null
2805 >     * @throws NullPointerException if the specified key or mappingFunction
2806 >     *         is null
2807 >     * @throws IllegalStateException if the computation detectably
2808 >     *         attempts a recursive update to this map that would
2809 >     *         otherwise never complete
2810 >     * @throws RuntimeException or Error if the mappingFunction does so,
2811 >     *         in which case the mapping is left unestablished
2812       */
2813 <    public V remove(Object key) {
2814 <        int hash = hash(key);
2815 <        return segmentFor(hash).remove(key, hash, null);
2813 >    public V computeIfAbsent
2814 >        (K key, Function<? super K, ? extends V> mappingFunction) {
2815 >        return internalComputeIfAbsent(key, mappingFunction);
2816      }
2817  
2818      /**
2819 <     * Remove entry for key only if currently mapped to given value.
2820 <     * Acts as
2821 <     * <pre>
2822 <     *  if (map.get(key).equals(value)) {
2823 <     *     map.remove(key);
2824 <     *     return true;
2825 <     * } else return false;
2826 <     * </pre>
2827 <     * except that the action is performed atomically.
2828 <     * @param key key with which the specified value is associated.
2829 <     * @param value value associated with the specified key.
2830 <     * @return true if the value was removed
2831 <     * @throws NullPointerException if the specified key is
2832 <     *            <tt>null</tt>.
2819 >     * If the value for the specified key is present and non-null,
2820 >     * attempts to compute a new mapping given the key and its current
2821 >     * mapped value.  The entire method invocation is performed
2822 >     * atomically.  Some attempted update operations on this map by
2823 >     * other threads may be blocked while computation is in progress,
2824 >     * so the computation should be short and simple, and must not
2825 >     * attempt to update any other mappings of this Map.
2826 >     *
2827 >     * @param key key with which a value may be associated
2828 >     * @param remappingFunction the function to compute a value
2829 >     * @return the new value associated with the specified key, or null if none
2830 >     * @throws NullPointerException if the specified key or remappingFunction
2831 >     *         is null
2832 >     * @throws IllegalStateException if the computation detectably
2833 >     *         attempts a recursive update to this map that would
2834 >     *         otherwise never complete
2835 >     * @throws RuntimeException or Error if the remappingFunction does so,
2836 >     *         in which case the mapping is unchanged
2837       */
2838 <    public boolean remove(Object key, Object value) {
2839 <        int hash = hash(key);
2840 <        return segmentFor(hash).remove(key, hash, value) != null;
2838 >    public V computeIfPresent
2839 >        (K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
2840 >        return internalCompute(key, true, remappingFunction);
2841 >    }
2842 >
2843 >    /**
2844 >     * Attempts to compute a mapping for the specified key and its
2845 >     * current mapped value (or {@code null} if there is no current
2846 >     * mapping). The entire method invocation is performed atomically.
2847 >     * Some attempted update operations on this map by other threads
2848 >     * may be blocked while computation is in progress, so the
2849 >     * computation should be short and simple, and must not attempt to
2850 >     * update any other mappings of this Map.
2851 >     *
2852 >     * @param key key with which the specified value is to be associated
2853 >     * @param remappingFunction the function to compute a value
2854 >     * @return the new value associated with the specified key, or null if none
2855 >     * @throws NullPointerException if the specified key or remappingFunction
2856 >     *         is null
2857 >     * @throws IllegalStateException if the computation detectably
2858 >     *         attempts a recursive update to this map that would
2859 >     *         otherwise never complete
2860 >     * @throws RuntimeException or Error if the remappingFunction does so,
2861 >     *         in which case the mapping is unchanged
2862 >     */
2863 >    public V compute
2864 >        (K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
2865 >        return internalCompute(key, false, remappingFunction);
2866      }
2867  
2868      /**
2869 <     * Removes all mappings from this map.
2869 >     * If the specified key is not already associated with a
2870 >     * (non-null) value, associates it with the given value.
2871 >     * Otherwise, replaces the value with the results of the given
2872 >     * remapping function, or removes if {@code null}. The entire
2873 >     * method invocation is performed atomically.  Some attempted
2874 >     * update operations on this map by other threads may be blocked
2875 >     * while computation is in progress, so the computation should be
2876 >     * short and simple, and must not attempt to update any other
2877 >     * mappings of this Map.
2878 >     *
2879 >     * @param key key with which the specified value is to be associated
2880 >     * @param value the value to use if absent
2881 >     * @param remappingFunction the function to recompute a value if present
2882 >     * @return the new value associated with the specified key, or null if none
2883 >     * @throws NullPointerException if the specified key or the
2884 >     *         remappingFunction is null
2885 >     * @throws RuntimeException or Error if the remappingFunction does so,
2886 >     *         in which case the mapping is unchanged
2887       */
2888 <    public void clear() {
2889 <        for (int i = 0; i < segments.length; ++i)
2890 <            segments[i].clear();
2888 >    public V merge
2889 >        (K key, V value,
2890 >         BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
2891 >        return internalMerge(key, value, remappingFunction);
2892      }
2893  
2894 +    /**
2895 +     * Removes the key (and its corresponding value) from this map.
2896 +     * This method does nothing if the key is not in the map.
2897 +     *
2898 +     * @param  key the key that needs to be removed
2899 +     * @return the previous value associated with {@code key}, or
2900 +     *         {@code null} if there was no mapping for {@code key}
2901 +     * @throws NullPointerException if the specified key is null
2902 +     */
2903 +    public V remove(Object key) {
2904 +        return internalReplace(key, null, null);
2905 +    }
2906  
2907      /**
2908 <     * Returns a shallow copy of this
837 <     * <tt>ConcurrentHashMap</tt> instance: the keys and
838 <     * values themselves are not cloned.
2908 >     * {@inheritDoc}
2909       *
2910 <     * @return a shallow copy of this map.
2910 >     * @throws NullPointerException if the specified key is null
2911       */
2912 <    public Object clone() {
2913 <        // We cannot call super.clone, since it would share final
2914 <        // segments array, and there's no way to reassign finals.
2912 >    public boolean remove(Object key, Object value) {
2913 >        if (key == null)
2914 >            throw new NullPointerException();
2915 >        return value != null && internalReplace(key, null, value) != null;
2916 >    }
2917  
2918 <        float lf = segments[0].loadFactor;
2919 <        int segs = segments.length;
2920 <        int cap = (int)(size() / lf);
2921 <        if (cap < segs) cap = segs;
2922 <        ConcurrentHashMap<K,V> t = new ConcurrentHashMap<K,V>(cap, lf, segs);
2923 <        t.putAll(this);
2924 <        return t;
2918 >    /**
2919 >     * {@inheritDoc}
2920 >     *
2921 >     * @throws NullPointerException if any of the arguments are null
2922 >     */
2923 >    public boolean replace(K key, V oldValue, V newValue) {
2924 >        if (key == null || oldValue == null || newValue == null)
2925 >            throw new NullPointerException();
2926 >        return internalReplace(key, newValue, oldValue) != null;
2927      }
2928  
2929      /**
2930 <     * Returns a set view of the keys contained in this map.  The set is
857 <     * backed by the map, so changes to the map are reflected in the set, and
858 <     * vice-versa.  The set supports element removal, which removes the
859 <     * corresponding mapping from this map, via the <tt>Iterator.remove</tt>,
860 <     * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and
861 <     * <tt>clear</tt> operations.  It does not support the <tt>add</tt> or
862 <     * <tt>addAll</tt> operations.
863 <     * The returned <tt>iterator</tt> is a "weakly consistent" iterator that
864 <     * will never throw {@link java.util.ConcurrentModificationException},
865 <     * and guarantees to traverse elements as they existed upon
866 <     * construction of the iterator, and may (but is not guaranteed to)
867 <     * reflect any modifications subsequent to construction.
2930 >     * {@inheritDoc}
2931       *
2932 <     * @return a set view of the keys contained in this map.
2932 >     * @return the previous value associated with the specified key,
2933 >     *         or {@code null} if there was no mapping for the key
2934 >     * @throws NullPointerException if the specified key or value is null
2935       */
2936 <    public Set<K> keySet() {
2937 <        Set<K> ks = keySet;
2938 <        return (ks != null) ? ks : (keySet = new KeySet());
2936 >    public V replace(K key, V value) {
2937 >        if (key == null || value == null)
2938 >            throw new NullPointerException();
2939 >        return internalReplace(key, value, null);
2940      }
2941  
2942 +    /**
2943 +     * Removes all of the mappings from this map.
2944 +     */
2945 +    public void clear() {
2946 +        internalClear();
2947 +    }
2948  
2949      /**
2950 <     * Returns a collection view of the values contained in this map.  The
2951 <     * collection is backed by the map, so changes to the map are reflected in
2952 <     * the collection, and vice-versa.  The collection supports element
881 <     * removal, which removes the corresponding mapping from this map, via the
882 <     * <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
883 <     * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
884 <     * It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
885 <     * The returned <tt>iterator</tt> is a "weakly consistent" iterator that
886 <     * will never throw {@link java.util.ConcurrentModificationException},
887 <     * and guarantees to traverse elements as they existed upon
888 <     * construction of the iterator, and may (but is not guaranteed to)
889 <     * reflect any modifications subsequent to construction.
2950 >     * Returns a {@link Set} view of the keys contained in this map.
2951 >     * The set is backed by the map, so changes to the map are
2952 >     * reflected in the set, and vice-versa.
2953       *
2954 <     * @return a collection view of the values contained in this map.
2954 >     * @return the set view
2955       */
2956 <    public Collection<V> values() {
2957 <        Collection<V> vs = values;
2958 <        return (vs != null) ? vs : (values = new Values());
2956 >    public KeySetView<K,V> keySet() {
2957 >        KeySetView<K,V> ks = keySet;
2958 >        return (ks != null) ? ks : (keySet = new KeySetView<K,V>(this, null));
2959      }
2960  
2961 +    /**
2962 +     * Returns a {@link Set} view of the keys in this map, using the
2963 +     * given common mapped value for any additions (i.e., {@link
2964 +     * Collection#add} and {@link Collection#addAll(Collection)}).
2965 +     * This is of course only appropriate if it is acceptable to use
2966 +     * the same value for all additions from this view.
2967 +     *
2968 +     * @param mappedValue the mapped value to use for any additions
2969 +     * @return the set view
2970 +     * @throws NullPointerException if the mappedValue is null
2971 +     */
2972 +    public KeySetView<K,V> keySet(V mappedValue) {
2973 +        if (mappedValue == null)
2974 +            throw new NullPointerException();
2975 +        return new KeySetView<K,V>(this, mappedValue);
2976 +    }
2977  
2978      /**
2979 <     * Returns a collection view of the mappings contained in this map.  Each
2980 <     * element in the returned collection is a <tt>Map.Entry</tt>.  The
2981 <     * collection is backed by the map, so changes to the map are reflected in
2982 <     * the collection, and vice-versa.  The collection supports element
2983 <     * removal, which removes the corresponding mapping from the map, via the
2984 <     * <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
2985 <     * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
2986 <     * It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
2987 <     * The returned <tt>iterator</tt> is a "weakly consistent" iterator that
2988 <     * will never throw {@link java.util.ConcurrentModificationException},
2979 >     * Returns a {@link Collection} view of the values contained in this map.
2980 >     * The collection is backed by the map, so changes to the map are
2981 >     * reflected in the collection, and vice-versa.
2982 >     *
2983 >     * @return the collection view
2984 >     */
2985 >    public ValuesView<K,V> values() {
2986 >        ValuesView<K,V> vs = values;
2987 >        return (vs != null) ? vs : (values = new ValuesView<K,V>(this));
2988 >    }
2989 >
2990 >    /**
2991 >     * Returns a {@link Set} view of the mappings contained in this map.
2992 >     * The set is backed by the map, so changes to the map are
2993 >     * reflected in the set, and vice-versa.  The set supports element
2994 >     * removal, which removes the corresponding mapping from the map,
2995 >     * via the {@code Iterator.remove}, {@code Set.remove},
2996 >     * {@code removeAll}, {@code retainAll}, and {@code clear}
2997 >     * operations.  It does not support the {@code add} or
2998 >     * {@code addAll} operations.
2999 >     *
3000 >     * <p>The view's {@code iterator} is a "weakly consistent" iterator
3001 >     * that will never throw {@link ConcurrentModificationException},
3002       * and guarantees to traverse elements as they existed upon
3003       * construction of the iterator, and may (but is not guaranteed to)
3004       * reflect any modifications subsequent to construction.
3005       *
3006 <     * @return a collection view of the mappings contained in this map.
3006 >     * @return the set view
3007       */
3008      public Set<Map.Entry<K,V>> entrySet() {
3009 <        Set<Map.Entry<K,V>> es = entrySet;
3010 <        return (es != null) ? es : (entrySet = (Set<Map.Entry<K,V>>) (Set) new EntrySet());
3009 >        EntrySetView<K,V> es = entrySet;
3010 >        return (es != null) ? es : (entrySet = new EntrySetView<K,V>(this));
3011      }
3012  
921
3013      /**
3014       * Returns an enumeration of the keys in this table.
3015       *
3016 <     * @return  an enumeration of the keys in this table.
3017 <     * @see     #keySet
3016 >     * @return an enumeration of the keys in this table
3017 >     * @see #keySet()
3018       */
3019      public Enumeration<K> keys() {
3020 <        return new KeyIterator();
3020 >        return new KeyIterator<K,V>(this);
3021      }
3022  
3023      /**
3024       * Returns an enumeration of the values in this table.
934     * Use the Enumeration methods on the returned object to fetch the elements
935     * sequentially.
3025       *
3026 <     * @return  an enumeration of the values in this table.
3027 <     * @see     #values
3026 >     * @return an enumeration of the values in this table
3027 >     * @see #values()
3028       */
3029      public Enumeration<V> elements() {
3030 <        return new ValueIterator();
3030 >        return new ValueIterator<K,V>(this);
3031      }
3032  
3033 <    /* ---------------- Iterator Support -------------- */
3033 >    /**
3034 >     * Returns the hash code value for this {@link Map}, i.e.,
3035 >     * the sum of, for each key-value pair in the map,
3036 >     * {@code key.hashCode() ^ value.hashCode()}.
3037 >     *
3038 >     * @return the hash code value for this map
3039 >     */
3040 >    public int hashCode() {
3041 >        int h = 0;
3042 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3043 >        V v;
3044 >        while ((v = it.advanceValue()) != null) {
3045 >            h += it.nextKey.hashCode() ^ v.hashCode();
3046 >        }
3047 >        return h;
3048 >    }
3049  
3050 <    private abstract class HashIterator {
3051 <        private int nextSegmentIndex;
3052 <        private int nextTableIndex;
3053 <        private HashEntry[] currentTable;
3054 <        private HashEntry<K, V> nextEntry;
3055 <        private HashEntry<K, V> lastReturned;
3050 >    /**
3051 >     * Returns a string representation of this map.  The string
3052 >     * representation consists of a list of key-value mappings (in no
3053 >     * particular order) enclosed in braces ("{@code {}}").  Adjacent
3054 >     * mappings are separated by the characters {@code ", "} (comma
3055 >     * and space).  Each key-value mapping is rendered as the key
3056 >     * followed by an equals sign ("{@code =}") followed by the
3057 >     * associated value.
3058 >     *
3059 >     * @return a string representation of this map
3060 >     */
3061 >    public String toString() {
3062 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3063 >        StringBuilder sb = new StringBuilder();
3064 >        sb.append('{');
3065 >        V v;
3066 >        if ((v = it.advanceValue()) != null) {
3067 >            for (;;) {
3068 >                K k = it.nextKey;
3069 >                sb.append(k == this ? "(this Map)" : k);
3070 >                sb.append('=');
3071 >                sb.append(v == this ? "(this Map)" : v);
3072 >                if ((v = it.advanceValue()) == null)
3073 >                    break;
3074 >                sb.append(',').append(' ');
3075 >            }
3076 >        }
3077 >        return sb.append('}').toString();
3078 >    }
3079  
3080 <        private HashIterator() {
3081 <            nextSegmentIndex = segments.length - 1;
3082 <            nextTableIndex = -1;
3083 <            advance();
3080 >    /**
3081 >     * Compares the specified object with this map for equality.
3082 >     * Returns {@code true} if the given object is a map with the same
3083 >     * mappings as this map.  This operation may return misleading
3084 >     * results if either map is concurrently modified during execution
3085 >     * of this method.
3086 >     *
3087 >     * @param o object to be compared for equality with this map
3088 >     * @return {@code true} if the specified object is equal to this map
3089 >     */
3090 >    public boolean equals(Object o) {
3091 >        if (o != this) {
3092 >            if (!(o instanceof Map))
3093 >                return false;
3094 >            Map<?,?> m = (Map<?,?>) o;
3095 >            Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3096 >            V val;
3097 >            while ((val = it.advanceValue()) != null) {
3098 >                Object v = m.get(it.nextKey);
3099 >                if (v == null || (v != val && !v.equals(val)))
3100 >                    return false;
3101 >            }
3102 >            for (Map.Entry<?,?> e : m.entrySet()) {
3103 >                Object mk, mv, v;
3104 >                if ((mk = e.getKey()) == null ||
3105 >                    (mv = e.getValue()) == null ||
3106 >                    (v = internalGet(mk)) == null ||
3107 >                    (mv != v && !mv.equals(v)))
3108 >                    return false;
3109 >            }
3110          }
3111 +        return true;
3112 +    }
3113  
3114 <        public boolean hasMoreElements() { return hasNext(); }
3114 >    /* ----------------Iterators -------------- */
3115  
3116 <        private void advance() {
3117 <            if (nextEntry != null && (nextEntry = nextEntry.next) != null)
3118 <                return;
3116 >    @SuppressWarnings("serial") static final class KeyIterator<K,V>
3117 >        extends Traverser<K,V,Object>
3118 >        implements Spliterator<K>, Iterator<K>, Enumeration<K> {
3119 >        KeyIterator(ConcurrentHashMap<K,V> map) { super(map); }
3120 >        KeyIterator(ConcurrentHashMap<K,V> map, Traverser<K,V,Object> it) {
3121 >            super(map, it);
3122 >        }
3123 >        public Spliterator<K> trySplit() {
3124 >            return (baseLimit - baseIndex <= 1) ? null :
3125 >                new KeyIterator<K,V>(map, this);
3126 >        }
3127 >        public final K next() {
3128 >            K k;
3129 >            if ((k = (nextVal == null) ? advanceKey() : nextKey) == null)
3130 >                throw new NoSuchElementException();
3131 >            nextVal = null;
3132 >            return k;
3133 >        }
3134  
3135 <            while (nextTableIndex >= 0) {
966 <                if ( (nextEntry = (HashEntry<K,V>)currentTable[nextTableIndex--]) != null)
967 <                    return;
968 <            }
3135 >        public final K nextElement() { return next(); }
3136  
3137 <            while (nextSegmentIndex >= 0) {
3138 <                Segment<K,V> seg = (Segment<K,V>)segments[nextSegmentIndex--];
3139 <                if (seg.count != 0) {
3140 <                    currentTable = seg.table;
3141 <                    for (int j = currentTable.length - 1; j >= 0; --j) {
3142 <                        if ( (nextEntry = (HashEntry<K,V>)currentTable[j]) != null) {
3143 <                            nextTableIndex = j - 1;
3144 <                            return;
3137 >        public Iterator<K> iterator() { return this; }
3138 >
3139 >        public void forEachRemaining(Consumer<? super K> action) {
3140 >            forEachKey(action);
3141 >        }
3142 >
3143 >        public boolean tryAdvance(Consumer<? super K> block) {
3144 >            if (block == null) throw new NullPointerException();
3145 >            K k;
3146 >            if ((k = advanceKey()) == null)
3147 >                return false;
3148 >            block.accept(k);
3149 >            return true;
3150 >        }
3151 >
3152 >        public int characteristics() {
3153 >            return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3154 >                Spliterator.NONNULL;
3155 >        }
3156 >
3157 >    }
3158 >
3159 >    @SuppressWarnings("serial") static final class ValueIterator<K,V>
3160 >        extends Traverser<K,V,Object>
3161 >        implements Spliterator<V>, Iterator<V>, Enumeration<V> {
3162 >        ValueIterator(ConcurrentHashMap<K,V> map) { super(map); }
3163 >        ValueIterator(ConcurrentHashMap<K,V> map, Traverser<K,V,Object> it) {
3164 >            super(map, it);
3165 >        }
3166 >        public Spliterator<V> trySplit() {
3167 >            return (baseLimit - baseIndex <= 1) ? null :
3168 >                new ValueIterator<K,V>(map, this);
3169 >        }
3170 >
3171 >        public final V next() {
3172 >            V v;
3173 >            if ((v = nextVal) == null && (v = advanceValue()) == null)
3174 >                throw new NoSuchElementException();
3175 >            nextVal = null;
3176 >            return v;
3177 >        }
3178 >
3179 >        public final V nextElement() { return next(); }
3180 >
3181 >        public Iterator<V> iterator() { return this; }
3182 >
3183 >        public void forEachRemaining(Consumer<? super V> action) {
3184 >            forEachValue(action);
3185 >        }
3186 >
3187 >        public boolean tryAdvance(Consumer<? super V> block) {
3188 >            V v;
3189 >            if (block == null) throw new NullPointerException();
3190 >            if ((v = advanceValue()) == null)
3191 >                return false;
3192 >            block.accept(v);
3193 >            return true;
3194 >        }
3195 >
3196 >        public int characteristics() {
3197 >            return Spliterator.CONCURRENT | Spliterator.NONNULL;
3198 >        }
3199 >    }
3200 >
3201 >    @SuppressWarnings("serial") static final class EntryIterator<K,V>
3202 >        extends Traverser<K,V,Object>
3203 >        implements Spliterator<Map.Entry<K,V>>, Iterator<Map.Entry<K,V>> {
3204 >        EntryIterator(ConcurrentHashMap<K,V> map) { super(map); }
3205 >        EntryIterator(ConcurrentHashMap<K,V> map, Traverser<K,V,Object> it) {
3206 >            super(map, it);
3207 >        }
3208 >        public Spliterator<Map.Entry<K,V>> trySplit() {
3209 >            return (baseLimit - baseIndex <= 1) ? null :
3210 >                new EntryIterator<K,V>(map, this);
3211 >        }
3212 >
3213 >        public final Map.Entry<K,V> next() {
3214 >            V v;
3215 >            if ((v = nextVal) == null && (v = advanceValue()) == null)
3216 >                throw new NoSuchElementException();
3217 >            K k = nextKey;
3218 >            nextVal = null;
3219 >            return new MapEntry<K,V>(k, v, map);
3220 >        }
3221 >
3222 >        public Iterator<Map.Entry<K,V>> iterator() { return this; }
3223 >
3224 >        public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
3225 >            if (action == null) throw new NullPointerException();
3226 >            V v;
3227 >            while ((v = advanceValue()) != null)
3228 >                action.accept(entryFor(nextKey, v));
3229 >        }
3230 >
3231 >        public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> block) {
3232 >            V v;
3233 >            if (block == null) throw new NullPointerException();
3234 >            if ((v = advanceValue()) == null)
3235 >                return false;
3236 >            block.accept(entryFor(nextKey, v));
3237 >            return true;
3238 >        }
3239 >
3240 >        public int characteristics() {
3241 >            return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3242 >                Spliterator.NONNULL;
3243 >        }
3244 >    }
3245 >
3246 >    /**
3247 >     * Exported Entry for iterators
3248 >     */
3249 >    static final class MapEntry<K,V> implements Map.Entry<K,V> {
3250 >        final K key; // non-null
3251 >        V val;       // non-null
3252 >        final ConcurrentHashMap<K,V> map;
3253 >        MapEntry(K key, V val, ConcurrentHashMap<K,V> map) {
3254 >            this.key = key;
3255 >            this.val = val;
3256 >            this.map = map;
3257 >        }
3258 >        public final K getKey()       { return key; }
3259 >        public final V getValue()     { return val; }
3260 >        public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
3261 >        public final String toString(){ return key + "=" + val; }
3262 >
3263 >        public final boolean equals(Object o) {
3264 >            Object k, v; Map.Entry<?,?> e;
3265 >            return ((o instanceof Map.Entry) &&
3266 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
3267 >                    (v = e.getValue()) != null &&
3268 >                    (k == key || k.equals(key)) &&
3269 >                    (v == val || v.equals(val)));
3270 >        }
3271 >
3272 >        /**
3273 >         * Sets our entry's value and writes through to the map. The
3274 >         * value to return is somewhat arbitrary here. Since we do not
3275 >         * necessarily track asynchronous changes, the most recent
3276 >         * "previous" value could be different from what we return (or
3277 >         * could even have been removed in which case the put will
3278 >         * re-establish). We do not and cannot guarantee more.
3279 >         */
3280 >        public final V setValue(V value) {
3281 >            if (value == null) throw new NullPointerException();
3282 >            V v = val;
3283 >            val = value;
3284 >            map.put(key, value);
3285 >            return v;
3286 >        }
3287 >    }
3288 >
3289 >    /**
3290 >     * Returns exportable snapshot entry for the given key and value
3291 >     * when write-through can't or shouldn't be used.
3292 >     */
3293 >    static <K,V> AbstractMap.SimpleEntry<K,V> entryFor(K k, V v) {
3294 >        return new AbstractMap.SimpleEntry<K,V>(k, v);
3295 >    }
3296 >
3297 >    /* ---------------- Serialization Support -------------- */
3298 >
3299 >    /**
3300 >     * Stripped-down version of helper class used in previous version,
3301 >     * declared for the sake of serialization compatibility
3302 >     */
3303 >    static class Segment<K,V> implements Serializable {
3304 >        private static final long serialVersionUID = 2249069246763182397L;
3305 >        final float loadFactor;
3306 >        Segment(float lf) { this.loadFactor = lf; }
3307 >    }
3308 >
3309 >    /**
3310 >     * Saves the state of the {@code ConcurrentHashMap} instance to a
3311 >     * stream (i.e., serializes it).
3312 >     * @param s the stream
3313 >     * @serialData
3314 >     * the key (Object) and value (Object)
3315 >     * for each key-value mapping, followed by a null pair.
3316 >     * The key-value mappings are emitted in no particular order.
3317 >     */
3318 >    @SuppressWarnings("unchecked") private void writeObject
3319 >        (java.io.ObjectOutputStream s)
3320 >        throws java.io.IOException {
3321 >        if (segments == null) { // for serialization compatibility
3322 >            segments = (Segment<K,V>[])
3323 >                new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
3324 >            for (int i = 0; i < segments.length; ++i)
3325 >                segments[i] = new Segment<K,V>(LOAD_FACTOR);
3326 >        }
3327 >        s.defaultWriteObject();
3328 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3329 >        V v;
3330 >        while ((v = it.advanceValue()) != null) {
3331 >            s.writeObject(it.nextKey);
3332 >            s.writeObject(v);
3333 >        }
3334 >        s.writeObject(null);
3335 >        s.writeObject(null);
3336 >        segments = null; // throw away
3337 >    }
3338 >
3339 >    /**
3340 >     * Reconstitutes the instance from a stream (that is, deserializes it).
3341 >     * @param s the stream
3342 >     */
3343 >    @SuppressWarnings("unchecked") private void readObject
3344 >        (java.io.ObjectInputStream s)
3345 >        throws java.io.IOException, ClassNotFoundException {
3346 >        s.defaultReadObject();
3347 >        this.segments = null; // unneeded
3348 >
3349 >        // Create all nodes, then place in table once size is known
3350 >        long size = 0L;
3351 >        Node<V> p = null;
3352 >        for (;;) {
3353 >            K k = (K) s.readObject();
3354 >            V v = (V) s.readObject();
3355 >            if (k != null && v != null) {
3356 >                int h = spread(k.hashCode());
3357 >                p = new Node<V>(h, k, v, p);
3358 >                ++size;
3359 >            }
3360 >            else
3361 >                break;
3362 >        }
3363 >        if (p != null) {
3364 >            boolean init = false;
3365 >            int n;
3366 >            if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
3367 >                n = MAXIMUM_CAPACITY;
3368 >            else {
3369 >                int sz = (int)size;
3370 >                n = tableSizeFor(sz + (sz >>> 1) + 1);
3371 >            }
3372 >            int sc = sizeCtl;
3373 >            boolean collide = false;
3374 >            if (n > sc &&
3375 >                U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
3376 >                try {
3377 >                    if (table == null) {
3378 >                        init = true;
3379 >                        @SuppressWarnings("rawtypes") Node[] rt = new Node[n];
3380 >                        Node<V>[] tab = (Node<V>[])rt;
3381 >                        int mask = n - 1;
3382 >                        while (p != null) {
3383 >                            int j = p.hash & mask;
3384 >                            Node<V> next = p.next;
3385 >                            Node<V> q = p.next = tabAt(tab, j);
3386 >                            setTabAt(tab, j, p);
3387 >                            if (!collide && q != null && q.hash == p.hash)
3388 >                                collide = true;
3389 >                            p = next;
3390 >                        }
3391 >                        table = tab;
3392 >                        addCount(size, -1);
3393 >                        sc = n - (n >>> 2);
3394 >                    }
3395 >                } finally {
3396 >                    sizeCtl = sc;
3397 >                }
3398 >                if (collide) { // rescan and convert to TreeBins
3399 >                    Node<V>[] tab = table;
3400 >                    for (int i = 0; i < tab.length; ++i) {
3401 >                        int c = 0;
3402 >                        for (Node<V> e = tabAt(tab, i); e != null; e = e.next) {
3403 >                            if (++c > TREE_THRESHOLD &&
3404 >                                (e.key instanceof Comparable)) {
3405 >                                replaceWithTreeBin(tab, i, e.key);
3406 >                                break;
3407 >                            }
3408                          }
3409                      }
3410                  }
3411              }
3412 +            if (!init) { // Can only happen if unsafely published.
3413 +                while (p != null) {
3414 +                    internalPut((K)p.key, p.val, false);
3415 +                    p = p.next;
3416 +                }
3417 +            }
3418          }
3419 +    }
3420  
3421 <        public boolean hasNext() { return nextEntry != null; }
3421 >    // -------------------------------------------------------
3422  
3423 <        HashEntry<K,V> nextEntry() {
3424 <            if (nextEntry == null)
3425 <                throw new NoSuchElementException();
3426 <            lastReturned = nextEntry;
3427 <            advance();
3428 <            return lastReturned;
3423 >    // Sequential bulk operations
3424 >
3425 >    /**
3426 >     * Performs the given action for each (key, value).
3427 >     *
3428 >     * @param action the action
3429 >     */
3430 >    public void forEachSequentially
3431 >        (BiConsumer<? super K, ? super V> action) {
3432 >        if (action == null) throw new NullPointerException();
3433 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3434 >        V v;
3435 >        while ((v = it.advanceValue()) != null)
3436 >            action.accept(it.nextKey, v);
3437 >    }
3438 >
3439 >    /**
3440 >     * Performs the given action for each non-null transformation
3441 >     * of each (key, value).
3442 >     *
3443 >     * @param transformer a function returning the transformation
3444 >     * for an element, or null if there is no transformation (in
3445 >     * which case the action is not applied)
3446 >     * @param action the action
3447 >     */
3448 >    public <U> void forEachSequentially
3449 >        (BiFunction<? super K, ? super V, ? extends U> transformer,
3450 >         Consumer<? super U> action) {
3451 >        if (transformer == null || action == null)
3452 >            throw new NullPointerException();
3453 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3454 >        V v; U u;
3455 >        while ((v = it.advanceValue()) != null) {
3456 >            if ((u = transformer.apply(it.nextKey, v)) != null)
3457 >                action.accept(u);
3458          }
3459 +    }
3460  
3461 <        public void remove() {
3462 <            if (lastReturned == null)
3463 <                throw new IllegalStateException();
3464 <            ConcurrentHashMap.this.remove(lastReturned.key);
3465 <            lastReturned = null;
3461 >    /**
3462 >     * Returns a non-null result from applying the given search
3463 >     * function on each (key, value), or null if none.
3464 >     *
3465 >     * @param searchFunction a function returning a non-null
3466 >     * result on success, else null
3467 >     * @return a non-null result from applying the given search
3468 >     * function on each (key, value), or null if none
3469 >     */
3470 >    public <U> U searchSequentially
3471 >        (BiFunction<? super K, ? super V, ? extends U> searchFunction) {
3472 >        if (searchFunction == null) throw new NullPointerException();
3473 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3474 >        V v; U u;
3475 >        while ((v = it.advanceValue()) != null) {
3476 >            if ((u = searchFunction.apply(it.nextKey, v)) != null)
3477 >                return u;
3478 >        }
3479 >        return null;
3480 >    }
3481 >
3482 >    /**
3483 >     * Returns the result of accumulating the given transformation
3484 >     * of all (key, value) pairs using the given reducer to
3485 >     * combine values, or null if none.
3486 >     *
3487 >     * @param transformer a function returning the transformation
3488 >     * for an element, or null if there is no transformation (in
3489 >     * which case it is not combined)
3490 >     * @param reducer a commutative associative combining function
3491 >     * @return the result of accumulating the given transformation
3492 >     * of all (key, value) pairs
3493 >     */
3494 >    public <U> U reduceSequentially
3495 >        (BiFunction<? super K, ? super V, ? extends U> transformer,
3496 >         BiFunction<? super U, ? super U, ? extends U> reducer) {
3497 >        if (transformer == null || reducer == null)
3498 >            throw new NullPointerException();
3499 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3500 >        U r = null, u; V v;
3501 >        while ((v = it.advanceValue()) != null) {
3502 >            if ((u = transformer.apply(it.nextKey, v)) != null)
3503 >                r = (r == null) ? u : reducer.apply(r, u);
3504          }
3505 +        return r;
3506 +    }
3507 +
3508 +    /**
3509 +     * Returns the result of accumulating the given transformation
3510 +     * of all (key, value) pairs using the given reducer to
3511 +     * combine values, and the given basis as an identity value.
3512 +     *
3513 +     * @param transformer a function returning the transformation
3514 +     * for an element
3515 +     * @param basis the identity (initial default value) for the reduction
3516 +     * @param reducer a commutative associative combining function
3517 +     * @return the result of accumulating the given transformation
3518 +     * of all (key, value) pairs
3519 +     */
3520 +    public double reduceToDoubleSequentially
3521 +        (ToDoubleBiFunction<? super K, ? super V> transformer,
3522 +         double basis,
3523 +         DoubleBinaryOperator reducer) {
3524 +        if (transformer == null || reducer == null)
3525 +            throw new NullPointerException();
3526 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3527 +        double r = basis; V v;
3528 +        while ((v = it.advanceValue()) != null)
3529 +            r = reducer.applyAsDouble(r, transformer.applyAsDouble(it.nextKey, v));
3530 +        return r;
3531 +    }
3532 +
3533 +    /**
3534 +     * Returns the result of accumulating the given transformation
3535 +     * of all (key, value) pairs using the given reducer to
3536 +     * combine values, and the given basis as an identity value.
3537 +     *
3538 +     * @param transformer a function returning the transformation
3539 +     * for an element
3540 +     * @param basis the identity (initial default value) for the reduction
3541 +     * @param reducer a commutative associative combining function
3542 +     * @return the result of accumulating the given transformation
3543 +     * of all (key, value) pairs
3544 +     */
3545 +    public long reduceToLongSequentially
3546 +        (ToLongBiFunction<? super K, ? super V> transformer,
3547 +         long basis,
3548 +         LongBinaryOperator reducer) {
3549 +        if (transformer == null || reducer == null)
3550 +            throw new NullPointerException();
3551 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3552 +        long r = basis; V v;
3553 +        while ((v = it.advanceValue()) != null)
3554 +            r = reducer.applyAsLong(r, transformer.applyAsLong(it.nextKey, v));
3555 +        return r;
3556 +    }
3557 +
3558 +    /**
3559 +     * Returns the result of accumulating the given transformation
3560 +     * of all (key, value) pairs using the given reducer to
3561 +     * combine values, and the given basis as an identity value.
3562 +     *
3563 +     * @param transformer a function returning the transformation
3564 +     * for an element
3565 +     * @param basis the identity (initial default value) for the reduction
3566 +     * @param reducer a commutative associative combining function
3567 +     * @return the result of accumulating the given transformation
3568 +     * of all (key, value) pairs
3569 +     */
3570 +    public int reduceToIntSequentially
3571 +        (ToIntBiFunction<? super K, ? super V> transformer,
3572 +         int basis,
3573 +         IntBinaryOperator reducer) {
3574 +        if (transformer == null || reducer == null)
3575 +            throw new NullPointerException();
3576 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3577 +        int r = basis; V v;
3578 +        while ((v = it.advanceValue()) != null)
3579 +            r = reducer.applyAsInt(r, transformer.applyAsInt(it.nextKey, v));
3580 +        return r;
3581      }
3582  
3583 <    private class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> {
3584 <        public K next() { return super.nextEntry().key; }
3585 <        public K nextElement() { return super.nextEntry().key; }
3583 >    /**
3584 >     * Performs the given action for each key.
3585 >     *
3586 >     * @param action the action
3587 >     */
3588 >    public void forEachKeySequentially
3589 >        (Consumer<? super K> action) {
3590 >        new Traverser<K,V,Object>(this).forEachKey(action);
3591      }
3592  
3593 <    private class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> {
3594 <        public V next() { return super.nextEntry().value; }
3595 <        public V nextElement() { return super.nextEntry().value; }
3593 >    /**
3594 >     * Performs the given action for each non-null transformation
3595 >     * of each key.
3596 >     *
3597 >     * @param transformer a function returning the transformation
3598 >     * for an element, or null if there is no transformation (in
3599 >     * which case the action is not applied)
3600 >     * @param action the action
3601 >     */
3602 >    public <U> void forEachKeySequentially
3603 >        (Function<? super K, ? extends U> transformer,
3604 >         Consumer<? super U> action) {
3605 >        if (transformer == null || action == null)
3606 >            throw new NullPointerException();
3607 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3608 >        K k; U u;
3609 >        while ((k = it.advanceKey()) != null) {
3610 >            if ((u = transformer.apply(k)) != null)
3611 >                action.accept(u);
3612 >        }
3613      }
3614  
3615 <    private class EntryIterator extends HashIterator implements Iterator<Entry<K,V>> {
3616 <        public Map.Entry<K,V> next() { return super.nextEntry(); }
3615 >    /**
3616 >     * Returns a non-null result from applying the given search
3617 >     * function on each key, or null if none.
3618 >     *
3619 >     * @param searchFunction a function returning a non-null
3620 >     * result on success, else null
3621 >     * @return a non-null result from applying the given search
3622 >     * function on each key, or null if none
3623 >     */
3624 >    public <U> U searchKeysSequentially
3625 >        (Function<? super K, ? extends U> searchFunction) {
3626 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3627 >        K k; U u;
3628 >        while ((k = it.advanceKey()) != null) {
3629 >            if ((u = searchFunction.apply(k)) != null)
3630 >                return u;
3631 >        }
3632 >        return null;
3633      }
3634  
3635 <    private class KeySet extends AbstractSet<K> {
3636 <        public Iterator<K> iterator() {
3637 <            return new KeyIterator();
3635 >    /**
3636 >     * Returns the result of accumulating all keys using the given
3637 >     * reducer to combine values, or null if none.
3638 >     *
3639 >     * @param reducer a commutative associative combining function
3640 >     * @return the result of accumulating all keys using the given
3641 >     * reducer to combine values, or null if none
3642 >     */
3643 >    public K reduceKeysSequentially
3644 >        (BiFunction<? super K, ? super K, ? extends K> reducer) {
3645 >        if (reducer == null) throw new NullPointerException();
3646 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3647 >        K u, r = null;
3648 >        while ((u = it.advanceKey()) != null) {
3649 >            r = (r == null) ? u : reducer.apply(r, u);
3650          }
3651 <        public int size() {
3652 <            return ConcurrentHashMap.this.size();
3651 >        return r;
3652 >    }
3653 >
3654 >    /**
3655 >     * Returns the result of accumulating the given transformation
3656 >     * of all keys using the given reducer to combine values, or
3657 >     * null if none.
3658 >     *
3659 >     * @param transformer a function returning the transformation
3660 >     * for an element, or null if there is no transformation (in
3661 >     * which case it is not combined)
3662 >     * @param reducer a commutative associative combining function
3663 >     * @return the result of accumulating the given transformation
3664 >     * of all keys
3665 >     */
3666 >    public <U> U reduceKeysSequentially
3667 >        (Function<? super K, ? extends U> transformer,
3668 >         BiFunction<? super U, ? super U, ? extends U> reducer) {
3669 >        if (transformer == null || reducer == null)
3670 >            throw new NullPointerException();
3671 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3672 >        K k; U r = null, u;
3673 >        while ((k = it.advanceKey()) != null) {
3674 >            if ((u = transformer.apply(k)) != null)
3675 >                r = (r == null) ? u : reducer.apply(r, u);
3676          }
3677 <        public boolean contains(Object o) {
3678 <            return ConcurrentHashMap.this.containsKey(o);
3677 >        return r;
3678 >    }
3679 >
3680 >    /**
3681 >     * Returns the result of accumulating the given transformation
3682 >     * of all keys using the given reducer to combine values, and
3683 >     * the given basis as an identity value.
3684 >     *
3685 >     * @param transformer a function returning the transformation
3686 >     * for an element
3687 >     * @param basis the identity (initial default value) for the reduction
3688 >     * @param reducer a commutative associative combining function
3689 >     * @return the result of accumulating the given transformation
3690 >     * of all keys
3691 >     */
3692 >    public double reduceKeysToDoubleSequentially
3693 >        (ToDoubleFunction<? super K> transformer,
3694 >         double basis,
3695 >         DoubleBinaryOperator reducer) {
3696 >        if (transformer == null || reducer == null)
3697 >            throw new NullPointerException();
3698 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3699 >        double r = basis;
3700 >        K k;
3701 >        while ((k = it.advanceKey()) != null)
3702 >            r = reducer.applyAsDouble(r, transformer.applyAsDouble(k));
3703 >        return r;
3704 >    }
3705 >
3706 >    /**
3707 >     * Returns the result of accumulating the given transformation
3708 >     * of all keys using the given reducer to combine values, and
3709 >     * the given basis as an identity value.
3710 >     *
3711 >     * @param transformer a function returning the transformation
3712 >     * for an element
3713 >     * @param basis the identity (initial default value) for the reduction
3714 >     * @param reducer a commutative associative combining function
3715 >     * @return the result of accumulating the given transformation
3716 >     * of all keys
3717 >     */
3718 >    public long reduceKeysToLongSequentially
3719 >        (ToLongFunction<? super K> transformer,
3720 >         long basis,
3721 >         LongBinaryOperator reducer) {
3722 >        if (transformer == null || reducer == null)
3723 >            throw new NullPointerException();
3724 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3725 >        long r = basis;
3726 >        K k;
3727 >        while ((k = it.advanceKey()) != null)
3728 >            r = reducer.applyAsLong(r, transformer.applyAsLong(k));
3729 >        return r;
3730 >    }
3731 >
3732 >    /**
3733 >     * Returns the result of accumulating the given transformation
3734 >     * of all keys using the given reducer to combine values, and
3735 >     * the given basis as an identity value.
3736 >     *
3737 >     * @param transformer a function returning the transformation
3738 >     * for an element
3739 >     * @param basis the identity (initial default value) for the reduction
3740 >     * @param reducer a commutative associative combining function
3741 >     * @return the result of accumulating the given transformation
3742 >     * of all keys
3743 >     */
3744 >    public int reduceKeysToIntSequentially
3745 >        (ToIntFunction<? super K> transformer,
3746 >         int basis,
3747 >         IntBinaryOperator reducer) {
3748 >        if (transformer == null || reducer == null)
3749 >            throw new NullPointerException();
3750 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3751 >        int r = basis;
3752 >        K k;
3753 >        while ((k = it.advanceKey()) != null)
3754 >            r = reducer.applyAsInt(r, transformer.applyAsInt(k));
3755 >        return r;
3756 >    }
3757 >
3758 >    /**
3759 >     * Performs the given action for each value.
3760 >     *
3761 >     * @param action the action
3762 >     */
3763 >    public void forEachValueSequentially(Consumer<? super V> action) {
3764 >        new Traverser<K,V,Object>(this).forEachValue(action);
3765 >    }
3766 >
3767 >    /**
3768 >     * Performs the given action for each non-null transformation
3769 >     * of each value.
3770 >     *
3771 >     * @param transformer a function returning the transformation
3772 >     * for an element, or null if there is no transformation (in
3773 >     * which case the action is not applied)
3774 >     * @param action the action
3775 >     */
3776 >    public <U> void forEachValueSequentially
3777 >        (Function<? super V, ? extends U> transformer,
3778 >         Consumer<? super U> action) {
3779 >        if (transformer == null || action == null)
3780 >            throw new NullPointerException();
3781 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3782 >        V v; U u;
3783 >        while ((v = it.advanceValue()) != null) {
3784 >            if ((u = transformer.apply(v)) != null)
3785 >                action.accept(u);
3786          }
3787 <        public boolean remove(Object o) {
3788 <            return ConcurrentHashMap.this.remove(o) != null;
3787 >    }
3788 >
3789 >    /**
3790 >     * Returns a non-null result from applying the given search
3791 >     * function on each value, or null if none.
3792 >     *
3793 >     * @param searchFunction a function returning a non-null
3794 >     * result on success, else null
3795 >     * @return a non-null result from applying the given search
3796 >     * function on each value, or null if none
3797 >     */
3798 >    public <U> U searchValuesSequentially
3799 >        (Function<? super V, ? extends U> searchFunction) {
3800 >        if (searchFunction == null) throw new NullPointerException();
3801 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3802 >        V v; U u;
3803 >        while ((v = it.advanceValue()) != null) {
3804 >            if ((u = searchFunction.apply(v)) != null)
3805 >                return u;
3806          }
3807 <        public void clear() {
3808 <            ConcurrentHashMap.this.clear();
3807 >        return null;
3808 >    }
3809 >
3810 >    /**
3811 >     * Returns the result of accumulating all values using the
3812 >     * given reducer to combine values, or null if none.
3813 >     *
3814 >     * @param reducer a commutative associative combining function
3815 >     * @return the result of accumulating all values
3816 >     */
3817 >    public V reduceValuesSequentially
3818 >        (BiFunction<? super V, ? super V, ? extends V> reducer) {
3819 >        if (reducer == null) throw new NullPointerException();
3820 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3821 >        V r = null; V v;
3822 >        while ((v = it.advanceValue()) != null)
3823 >            r = (r == null) ? v : reducer.apply(r, v);
3824 >        return r;
3825 >    }
3826 >
3827 >    /**
3828 >     * Returns the result of accumulating the given transformation
3829 >     * of all values using the given reducer to combine values, or
3830 >     * null if none.
3831 >     *
3832 >     * @param transformer a function returning the transformation
3833 >     * for an element, or null if there is no transformation (in
3834 >     * which case it is not combined)
3835 >     * @param reducer a commutative associative combining function
3836 >     * @return the result of accumulating the given transformation
3837 >     * of all values
3838 >     */
3839 >    public <U> U reduceValuesSequentially
3840 >        (Function<? super V, ? extends U> transformer,
3841 >         BiFunction<? super U, ? super U, ? extends U> reducer) {
3842 >        if (transformer == null || reducer == null)
3843 >            throw new NullPointerException();
3844 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3845 >        U r = null, u; V v;
3846 >        while ((v = it.advanceValue()) != null) {
3847 >            if ((u = transformer.apply(v)) != null)
3848 >                r = (r == null) ? u : reducer.apply(r, u);
3849          }
3850 +        return r;
3851 +    }
3852 +
3853 +    /**
3854 +     * Returns the result of accumulating the given transformation
3855 +     * of all values using the given reducer to combine values,
3856 +     * and the given basis as an identity value.
3857 +     *
3858 +     * @param transformer a function returning the transformation
3859 +     * for an element
3860 +     * @param basis the identity (initial default value) for the reduction
3861 +     * @param reducer a commutative associative combining function
3862 +     * @return the result of accumulating the given transformation
3863 +     * of all values
3864 +     */
3865 +    public double reduceValuesToDoubleSequentially
3866 +        (ToDoubleFunction<? super V> transformer,
3867 +         double basis,
3868 +         DoubleBinaryOperator reducer) {
3869 +        if (transformer == null || reducer == null)
3870 +            throw new NullPointerException();
3871 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3872 +        double r = basis; V v;
3873 +        while ((v = it.advanceValue()) != null)
3874 +            r = reducer.applyAsDouble(r, transformer.applyAsDouble(v));
3875 +        return r;
3876 +    }
3877 +
3878 +    /**
3879 +     * Returns the result of accumulating the given transformation
3880 +     * of all values using the given reducer to combine values,
3881 +     * and the given basis as an identity value.
3882 +     *
3883 +     * @param transformer a function returning the transformation
3884 +     * for an element
3885 +     * @param basis the identity (initial default value) for the reduction
3886 +     * @param reducer a commutative associative combining function
3887 +     * @return the result of accumulating the given transformation
3888 +     * of all values
3889 +     */
3890 +    public long reduceValuesToLongSequentially
3891 +        (ToLongFunction<? super V> transformer,
3892 +         long basis,
3893 +         LongBinaryOperator reducer) {
3894 +        if (transformer == null || reducer == null)
3895 +            throw new NullPointerException();
3896 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3897 +        long r = basis; V v;
3898 +        while ((v = it.advanceValue()) != null)
3899 +            r = reducer.applyAsLong(r, transformer.applyAsLong(v));
3900 +        return r;
3901 +    }
3902 +
3903 +    /**
3904 +     * Returns the result of accumulating the given transformation
3905 +     * of all values using the given reducer to combine values,
3906 +     * and the given basis as an identity value.
3907 +     *
3908 +     * @param transformer a function returning the transformation
3909 +     * for an element
3910 +     * @param basis the identity (initial default value) for the reduction
3911 +     * @param reducer a commutative associative combining function
3912 +     * @return the result of accumulating the given transformation
3913 +     * of all values
3914 +     */
3915 +    public int reduceValuesToIntSequentially
3916 +        (ToIntFunction<? super V> transformer,
3917 +         int basis,
3918 +         IntBinaryOperator reducer) {
3919 +        if (transformer == null || reducer == null)
3920 +            throw new NullPointerException();
3921 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3922 +        int r = basis; V v;
3923 +        while ((v = it.advanceValue()) != null)
3924 +            r = reducer.applyAsInt(r, transformer.applyAsInt(v));
3925 +        return r;
3926      }
3927  
3928 <    private class Values extends AbstractCollection<V> {
3929 <        public Iterator<V> iterator() {
3930 <            return new ValueIterator();
3928 >    /**
3929 >     * Performs the given action for each entry.
3930 >     *
3931 >     * @param action the action
3932 >     */
3933 >    public void forEachEntrySequentially
3934 >        (Consumer<? super Map.Entry<K,V>> action) {
3935 >        if (action == null) throw new NullPointerException();
3936 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3937 >        V v;
3938 >        while ((v = it.advanceValue()) != null)
3939 >            action.accept(entryFor(it.nextKey, v));
3940 >    }
3941 >
3942 >    /**
3943 >     * Performs the given action for each non-null transformation
3944 >     * of each entry.
3945 >     *
3946 >     * @param transformer a function returning the transformation
3947 >     * for an element, or null if there is no transformation (in
3948 >     * which case the action is not applied)
3949 >     * @param action the action
3950 >     */
3951 >    public <U> void forEachEntrySequentially
3952 >        (Function<Map.Entry<K,V>, ? extends U> transformer,
3953 >         Consumer<? super U> action) {
3954 >        if (transformer == null || action == null)
3955 >            throw new NullPointerException();
3956 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3957 >        V v; U u;
3958 >        while ((v = it.advanceValue()) != null) {
3959 >            if ((u = transformer.apply(entryFor(it.nextKey, v))) != null)
3960 >                action.accept(u);
3961          }
3962 <        public int size() {
3963 <            return ConcurrentHashMap.this.size();
3962 >    }
3963 >
3964 >    /**
3965 >     * Returns a non-null result from applying the given search
3966 >     * function on each entry, or null if none.
3967 >     *
3968 >     * @param searchFunction a function returning a non-null
3969 >     * result on success, else null
3970 >     * @return a non-null result from applying the given search
3971 >     * function on each entry, or null if none
3972 >     */
3973 >    public <U> U searchEntriesSequentially
3974 >        (Function<Map.Entry<K,V>, ? extends U> searchFunction) {
3975 >        if (searchFunction == null) throw new NullPointerException();
3976 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3977 >        V v; U u;
3978 >        while ((v = it.advanceValue()) != null) {
3979 >            if ((u = searchFunction.apply(entryFor(it.nextKey, v))) != null)
3980 >                return u;
3981          }
3982 <        public boolean contains(Object o) {
3983 <            return ConcurrentHashMap.this.containsValue(o);
3982 >        return null;
3983 >    }
3984 >
3985 >    /**
3986 >     * Returns the result of accumulating all entries using the
3987 >     * given reducer to combine values, or null if none.
3988 >     *
3989 >     * @param reducer a commutative associative combining function
3990 >     * @return the result of accumulating all entries
3991 >     */
3992 >    public Map.Entry<K,V> reduceEntriesSequentially
3993 >        (BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
3994 >        if (reducer == null) throw new NullPointerException();
3995 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
3996 >        Map.Entry<K,V> r = null; V v;
3997 >        while ((v = it.advanceValue()) != null) {
3998 >            Map.Entry<K,V> u = entryFor(it.nextKey, v);
3999 >            r = (r == null) ? u : reducer.apply(r, u);
4000          }
4001 <        public void clear() {
4002 <            ConcurrentHashMap.this.clear();
4001 >        return r;
4002 >    }
4003 >
4004 >    /**
4005 >     * Returns the result of accumulating the given transformation
4006 >     * of all entries using the given reducer to combine values,
4007 >     * or null if none.
4008 >     *
4009 >     * @param transformer a function returning the transformation
4010 >     * for an element, or null if there is no transformation (in
4011 >     * which case it is not combined)
4012 >     * @param reducer a commutative associative combining function
4013 >     * @return the result of accumulating the given transformation
4014 >     * of all entries
4015 >     */
4016 >    public <U> U reduceEntriesSequentially
4017 >        (Function<Map.Entry<K,V>, ? extends U> transformer,
4018 >         BiFunction<? super U, ? super U, ? extends U> reducer) {
4019 >        if (transformer == null || reducer == null)
4020 >            throw new NullPointerException();
4021 >        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
4022 >        U r = null, u; V v;
4023 >        while ((v = it.advanceValue()) != null) {
4024 >            if ((u = transformer.apply(entryFor(it.nextKey, v))) != null)
4025 >                r = (r == null) ? u : reducer.apply(r, u);
4026          }
4027 +        return r;
4028 +    }
4029 +
4030 +    /**
4031 +     * Returns the result of accumulating the given transformation
4032 +     * of all entries using the given reducer to combine values,
4033 +     * and the given basis as an identity value.
4034 +     *
4035 +     * @param transformer a function returning the transformation
4036 +     * for an element
4037 +     * @param basis the identity (initial default value) for the reduction
4038 +     * @param reducer a commutative associative combining function
4039 +     * @return the result of accumulating the given transformation
4040 +     * of all entries
4041 +     */
4042 +    public double reduceEntriesToDoubleSequentially
4043 +        (ToDoubleFunction<Map.Entry<K,V>> transformer,
4044 +         double basis,
4045 +         DoubleBinaryOperator reducer) {
4046 +        if (transformer == null || reducer == null)
4047 +            throw new NullPointerException();
4048 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
4049 +        double r = basis; V v;
4050 +        while ((v = it.advanceValue()) != null)
4051 +            r = reducer.applyAsDouble(r, transformer.applyAsDouble(entryFor(it.nextKey, v)));
4052 +        return r;
4053 +    }
4054 +
4055 +    /**
4056 +     * Returns the result of accumulating the given transformation
4057 +     * of all entries using the given reducer to combine values,
4058 +     * and the given basis as an identity value.
4059 +     *
4060 +     * @param transformer a function returning the transformation
4061 +     * for an element
4062 +     * @param basis the identity (initial default value) for the reduction
4063 +     * @param reducer a commutative associative combining function
4064 +     * @return the result of accumulating the given transformation
4065 +     * of all entries
4066 +     */
4067 +    public long reduceEntriesToLongSequentially
4068 +        (ToLongFunction<Map.Entry<K,V>> transformer,
4069 +         long basis,
4070 +         LongBinaryOperator reducer) {
4071 +        if (transformer == null || reducer == null)
4072 +            throw new NullPointerException();
4073 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
4074 +        long r = basis; V v;
4075 +        while ((v = it.advanceValue()) != null)
4076 +            r = reducer.applyAsLong(r, transformer.applyAsLong(entryFor(it.nextKey, v)));
4077 +        return r;
4078 +    }
4079 +
4080 +    /**
4081 +     * Returns the result of accumulating the given transformation
4082 +     * of all entries using the given reducer to combine values,
4083 +     * and the given basis as an identity value.
4084 +     *
4085 +     * @param transformer a function returning the transformation
4086 +     * for an element
4087 +     * @param basis the identity (initial default value) for the reduction
4088 +     * @param reducer a commutative associative combining function
4089 +     * @return the result of accumulating the given transformation
4090 +     * of all entries
4091 +     */
4092 +    public int reduceEntriesToIntSequentially
4093 +        (ToIntFunction<Map.Entry<K,V>> transformer,
4094 +         int basis,
4095 +         IntBinaryOperator reducer) {
4096 +        if (transformer == null || reducer == null)
4097 +            throw new NullPointerException();
4098 +        Traverser<K,V,Object> it = new Traverser<K,V,Object>(this);
4099 +        int r = basis; V v;
4100 +        while ((v = it.advanceValue()) != null)
4101 +            r = reducer.applyAsInt(r, transformer.applyAsInt(entryFor(it.nextKey, v)));
4102 +        return r;
4103 +    }
4104 +
4105 +    // Parallel bulk operations
4106 +
4107 +    /**
4108 +     * Performs the given action for each (key, value).
4109 +     *
4110 +     * @param action the action
4111 +     */
4112 +    public void forEachInParallel(BiConsumer<? super K,? super V> action) {
4113 +        ForkJoinTasks.forEach
4114 +            (this, action).invoke();
4115 +    }
4116 +
4117 +    /**
4118 +     * Performs the given action for each non-null transformation
4119 +     * of each (key, value).
4120 +     *
4121 +     * @param transformer a function returning the transformation
4122 +     * for an element, or null if there is no transformation (in
4123 +     * which case the action is not applied)
4124 +     * @param action the action
4125 +     */
4126 +    public <U> void forEachInParallel
4127 +        (BiFunction<? super K, ? super V, ? extends U> transformer,
4128 +                            Consumer<? super U> action) {
4129 +        ForkJoinTasks.forEach
4130 +            (this, transformer, action).invoke();
4131 +    }
4132 +
4133 +    /**
4134 +     * Returns a non-null result from applying the given search
4135 +     * function on each (key, value), or null if none.  Upon
4136 +     * success, further element processing is suppressed and the
4137 +     * results of any other parallel invocations of the search
4138 +     * function are ignored.
4139 +     *
4140 +     * @param searchFunction a function returning a non-null
4141 +     * result on success, else null
4142 +     * @return a non-null result from applying the given search
4143 +     * function on each (key, value), or null if none
4144 +     */
4145 +    public <U> U searchInParallel
4146 +        (BiFunction<? super K, ? super V, ? extends U> searchFunction) {
4147 +        return ForkJoinTasks.search
4148 +            (this, searchFunction).invoke();
4149 +    }
4150 +
4151 +    /**
4152 +     * Returns the result of accumulating the given transformation
4153 +     * of all (key, value) pairs using the given reducer to
4154 +     * combine values, or null if none.
4155 +     *
4156 +     * @param transformer a function returning the transformation
4157 +     * for an element, or null if there is no transformation (in
4158 +     * which case it is not combined)
4159 +     * @param reducer a commutative associative combining function
4160 +     * @return the result of accumulating the given transformation
4161 +     * of all (key, value) pairs
4162 +     */
4163 +    public <U> U reduceInParallel
4164 +        (BiFunction<? super K, ? super V, ? extends U> transformer,
4165 +         BiFunction<? super U, ? super U, ? extends U> reducer) {
4166 +        return ForkJoinTasks.reduce
4167 +            (this, transformer, reducer).invoke();
4168 +    }
4169 +
4170 +    /**
4171 +     * Returns the result of accumulating the given transformation
4172 +     * of all (key, value) pairs using the given reducer to
4173 +     * combine values, and the given basis as an identity value.
4174 +     *
4175 +     * @param transformer a function returning the transformation
4176 +     * for an element
4177 +     * @param basis the identity (initial default value) for the reduction
4178 +     * @param reducer a commutative associative combining function
4179 +     * @return the result of accumulating the given transformation
4180 +     * of all (key, value) pairs
4181 +     */
4182 +    public double reduceToDoubleInParallel
4183 +        (ToDoubleBiFunction<? super K, ? super V> transformer,
4184 +         double basis,
4185 +         DoubleBinaryOperator reducer) {
4186 +        return ForkJoinTasks.reduceToDouble
4187 +            (this, transformer, basis, reducer).invoke();
4188 +    }
4189 +
4190 +    /**
4191 +     * Returns the result of accumulating the given transformation
4192 +     * of all (key, value) pairs using the given reducer to
4193 +     * combine values, and the given basis as an identity value.
4194 +     *
4195 +     * @param transformer a function returning the transformation
4196 +     * for an element
4197 +     * @param basis the identity (initial default value) for the reduction
4198 +     * @param reducer a commutative associative combining function
4199 +     * @return the result of accumulating the given transformation
4200 +     * of all (key, value) pairs
4201 +     */
4202 +    public long reduceToLongInParallel
4203 +        (ToLongBiFunction<? super K, ? super V> transformer,
4204 +         long basis,
4205 +         LongBinaryOperator reducer) {
4206 +        return ForkJoinTasks.reduceToLong
4207 +            (this, transformer, basis, reducer).invoke();
4208 +    }
4209 +
4210 +    /**
4211 +     * Returns the result of accumulating the given transformation
4212 +     * of all (key, value) pairs using the given reducer to
4213 +     * combine values, and the given basis as an identity value.
4214 +     *
4215 +     * @param transformer a function returning the transformation
4216 +     * for an element
4217 +     * @param basis the identity (initial default value) for the reduction
4218 +     * @param reducer a commutative associative combining function
4219 +     * @return the result of accumulating the given transformation
4220 +     * of all (key, value) pairs
4221 +     */
4222 +    public int reduceToIntInParallel
4223 +        (ToIntBiFunction<? super K, ? super V> transformer,
4224 +         int basis,
4225 +         IntBinaryOperator reducer) {
4226 +        return ForkJoinTasks.reduceToInt
4227 +            (this, transformer, basis, reducer).invoke();
4228 +    }
4229 +
4230 +    /**
4231 +     * Performs the given action for each key.
4232 +     *
4233 +     * @param action the action
4234 +     */
4235 +    public void forEachKeyInParallel(Consumer<? super K> action) {
4236 +        ForkJoinTasks.forEachKey
4237 +            (this, action).invoke();
4238 +    }
4239 +
4240 +    /**
4241 +     * Performs the given action for each non-null transformation
4242 +     * of each key.
4243 +     *
4244 +     * @param transformer a function returning the transformation
4245 +     * for an element, or null if there is no transformation (in
4246 +     * which case the action is not applied)
4247 +     * @param action the action
4248 +     */
4249 +    public <U> void forEachKeyInParallel
4250 +        (Function<? super K, ? extends U> transformer,
4251 +         Consumer<? super U> action) {
4252 +        ForkJoinTasks.forEachKey
4253 +            (this, transformer, action).invoke();
4254 +    }
4255 +
4256 +    /**
4257 +     * Returns a non-null result from applying the given search
4258 +     * function on each key, or null if none. Upon success,
4259 +     * further element processing is suppressed and the results of
4260 +     * any other parallel invocations of the search function are
4261 +     * ignored.
4262 +     *
4263 +     * @param searchFunction a function returning a non-null
4264 +     * result on success, else null
4265 +     * @return a non-null result from applying the given search
4266 +     * function on each key, or null if none
4267 +     */
4268 +    public <U> U searchKeysInParallel
4269 +        (Function<? super K, ? extends U> searchFunction) {
4270 +        return ForkJoinTasks.searchKeys
4271 +            (this, searchFunction).invoke();
4272 +    }
4273 +
4274 +    /**
4275 +     * Returns the result of accumulating all keys using the given
4276 +     * reducer to combine values, or null if none.
4277 +     *
4278 +     * @param reducer a commutative associative combining function
4279 +     * @return the result of accumulating all keys using the given
4280 +     * reducer to combine values, or null if none
4281 +     */
4282 +    public K reduceKeysInParallel
4283 +        (BiFunction<? super K, ? super K, ? extends K> reducer) {
4284 +        return ForkJoinTasks.reduceKeys
4285 +            (this, reducer).invoke();
4286 +    }
4287 +
4288 +    /**
4289 +     * Returns the result of accumulating the given transformation
4290 +     * of all keys using the given reducer to combine values, or
4291 +     * null if none.
4292 +     *
4293 +     * @param transformer a function returning the transformation
4294 +     * for an element, or null if there is no transformation (in
4295 +     * which case it is not combined)
4296 +     * @param reducer a commutative associative combining function
4297 +     * @return the result of accumulating the given transformation
4298 +     * of all keys
4299 +     */
4300 +    public <U> U reduceKeysInParallel
4301 +        (Function<? super K, ? extends U> transformer,
4302 +         BiFunction<? super U, ? super U, ? extends U> reducer) {
4303 +        return ForkJoinTasks.reduceKeys
4304 +            (this, transformer, reducer).invoke();
4305 +    }
4306 +
4307 +    /**
4308 +     * Returns the result of accumulating the given transformation
4309 +     * of all keys using the given reducer to combine values, and
4310 +     * the given basis as an identity value.
4311 +     *
4312 +     * @param transformer a function returning the transformation
4313 +     * for an element
4314 +     * @param basis the identity (initial default value) for the reduction
4315 +     * @param reducer a commutative associative combining function
4316 +     * @return the result of accumulating the given transformation
4317 +     * of all keys
4318 +     */
4319 +    public double reduceKeysToDoubleInParallel
4320 +        (ToDoubleFunction<? super K> transformer,
4321 +         double basis,
4322 +         DoubleBinaryOperator reducer) {
4323 +        return ForkJoinTasks.reduceKeysToDouble
4324 +            (this, transformer, basis, reducer).invoke();
4325 +    }
4326 +
4327 +    /**
4328 +     * Returns the result of accumulating the given transformation
4329 +     * of all keys using the given reducer to combine values, and
4330 +     * the given basis as an identity value.
4331 +     *
4332 +     * @param transformer a function returning the transformation
4333 +     * for an element
4334 +     * @param basis the identity (initial default value) for the reduction
4335 +     * @param reducer a commutative associative combining function
4336 +     * @return the result of accumulating the given transformation
4337 +     * of all keys
4338 +     */
4339 +    public long reduceKeysToLongInParallel
4340 +        (ToLongFunction<? super K> transformer,
4341 +         long basis,
4342 +         LongBinaryOperator reducer) {
4343 +        return ForkJoinTasks.reduceKeysToLong
4344 +            (this, transformer, basis, reducer).invoke();
4345 +    }
4346 +
4347 +    /**
4348 +     * Returns the result of accumulating the given transformation
4349 +     * of all keys using the given reducer to combine values, and
4350 +     * the given basis as an identity value.
4351 +     *
4352 +     * @param transformer a function returning the transformation
4353 +     * for an element
4354 +     * @param basis the identity (initial default value) for the reduction
4355 +     * @param reducer a commutative associative combining function
4356 +     * @return the result of accumulating the given transformation
4357 +     * of all keys
4358 +     */
4359 +    public int reduceKeysToIntInParallel
4360 +        (ToIntFunction<? super K> transformer,
4361 +         int basis,
4362 +         IntBinaryOperator reducer) {
4363 +        return ForkJoinTasks.reduceKeysToInt
4364 +            (this, transformer, basis, reducer).invoke();
4365 +    }
4366 +
4367 +    /**
4368 +     * Performs the given action for each value.
4369 +     *
4370 +     * @param action the action
4371 +     */
4372 +    public void forEachValueInParallel(Consumer<? super V> action) {
4373 +        ForkJoinTasks.forEachValue
4374 +            (this, action).invoke();
4375 +    }
4376 +
4377 +    /**
4378 +     * Performs the given action for each non-null transformation
4379 +     * of each value.
4380 +     *
4381 +     * @param transformer a function returning the transformation
4382 +     * for an element, or null if there is no transformation (in
4383 +     * which case the action is not applied)
4384 +     * @param action the action
4385 +     */
4386 +    public <U> void forEachValueInParallel
4387 +        (Function<? super V, ? extends U> transformer,
4388 +         Consumer<? super U> action) {
4389 +        ForkJoinTasks.forEachValue
4390 +            (this, transformer, action).invoke();
4391 +    }
4392 +
4393 +    /**
4394 +     * Returns a non-null result from applying the given search
4395 +     * function on each value, or null if none.  Upon success,
4396 +     * further element processing is suppressed and the results of
4397 +     * any other parallel invocations of the search function are
4398 +     * ignored.
4399 +     *
4400 +     * @param searchFunction a function returning a non-null
4401 +     * result on success, else null
4402 +     * @return a non-null result from applying the given search
4403 +     * function on each value, or null if none
4404 +     */
4405 +    public <U> U searchValuesInParallel
4406 +        (Function<? super V, ? extends U> searchFunction) {
4407 +        return ForkJoinTasks.searchValues
4408 +            (this, searchFunction).invoke();
4409 +    }
4410 +
4411 +    /**
4412 +     * Returns the result of accumulating all values using the
4413 +     * given reducer to combine values, or null if none.
4414 +     *
4415 +     * @param reducer a commutative associative combining function
4416 +     * @return the result of accumulating all values
4417 +     */
4418 +    public V reduceValuesInParallel
4419 +        (BiFunction<? super V, ? super V, ? extends V> reducer) {
4420 +        return ForkJoinTasks.reduceValues
4421 +            (this, reducer).invoke();
4422 +    }
4423 +
4424 +    /**
4425 +     * Returns the result of accumulating the given transformation
4426 +     * of all values using the given reducer to combine values, or
4427 +     * null if none.
4428 +     *
4429 +     * @param transformer a function returning the transformation
4430 +     * for an element, or null if there is no transformation (in
4431 +     * which case it is not combined)
4432 +     * @param reducer a commutative associative combining function
4433 +     * @return the result of accumulating the given transformation
4434 +     * of all values
4435 +     */
4436 +    public <U> U reduceValuesInParallel
4437 +        (Function<? super V, ? extends U> transformer,
4438 +         BiFunction<? super U, ? super U, ? extends U> reducer) {
4439 +        return ForkJoinTasks.reduceValues
4440 +            (this, transformer, reducer).invoke();
4441 +    }
4442 +
4443 +    /**
4444 +     * Returns the result of accumulating the given transformation
4445 +     * of all values using the given reducer to combine values,
4446 +     * and the given basis as an identity value.
4447 +     *
4448 +     * @param transformer a function returning the transformation
4449 +     * for an element
4450 +     * @param basis the identity (initial default value) for the reduction
4451 +     * @param reducer a commutative associative combining function
4452 +     * @return the result of accumulating the given transformation
4453 +     * of all values
4454 +     */
4455 +    public double reduceValuesToDoubleInParallel
4456 +        (ToDoubleFunction<? super V> transformer,
4457 +         double basis,
4458 +         DoubleBinaryOperator reducer) {
4459 +        return ForkJoinTasks.reduceValuesToDouble
4460 +            (this, transformer, basis, reducer).invoke();
4461 +    }
4462 +
4463 +    /**
4464 +     * Returns the result of accumulating the given transformation
4465 +     * of all values using the given reducer to combine values,
4466 +     * and the given basis as an identity value.
4467 +     *
4468 +     * @param transformer a function returning the transformation
4469 +     * for an element
4470 +     * @param basis the identity (initial default value) for the reduction
4471 +     * @param reducer a commutative associative combining function
4472 +     * @return the result of accumulating the given transformation
4473 +     * of all values
4474 +     */
4475 +    public long reduceValuesToLongInParallel
4476 +        (ToLongFunction<? super V> transformer,
4477 +         long basis,
4478 +         LongBinaryOperator reducer) {
4479 +        return ForkJoinTasks.reduceValuesToLong
4480 +            (this, transformer, basis, reducer).invoke();
4481 +    }
4482 +
4483 +    /**
4484 +     * Returns the result of accumulating the given transformation
4485 +     * of all values using the given reducer to combine values,
4486 +     * and the given basis as an identity value.
4487 +     *
4488 +     * @param transformer a function returning the transformation
4489 +     * for an element
4490 +     * @param basis the identity (initial default value) for the reduction
4491 +     * @param reducer a commutative associative combining function
4492 +     * @return the result of accumulating the given transformation
4493 +     * of all values
4494 +     */
4495 +    public int reduceValuesToIntInParallel
4496 +        (ToIntFunction<? super V> transformer,
4497 +         int basis,
4498 +         IntBinaryOperator reducer) {
4499 +        return ForkJoinTasks.reduceValuesToInt
4500 +            (this, transformer, basis, reducer).invoke();
4501 +    }
4502 +
4503 +    /**
4504 +     * Performs the given action for each entry.
4505 +     *
4506 +     * @param action the action
4507 +     */
4508 +    public void forEachEntryInParallel(Consumer<? super Map.Entry<K,V>> action) {
4509 +        ForkJoinTasks.forEachEntry
4510 +            (this, action).invoke();
4511 +    }
4512 +
4513 +    /**
4514 +     * Performs the given action for each non-null transformation
4515 +     * of each entry.
4516 +     *
4517 +     * @param transformer a function returning the transformation
4518 +     * for an element, or null if there is no transformation (in
4519 +     * which case the action is not applied)
4520 +     * @param action the action
4521 +     */
4522 +    public <U> void forEachEntryInParallel
4523 +        (Function<Map.Entry<K,V>, ? extends U> transformer,
4524 +         Consumer<? super U> action) {
4525 +        ForkJoinTasks.forEachEntry
4526 +            (this, transformer, action).invoke();
4527 +    }
4528 +
4529 +    /**
4530 +     * Returns a non-null result from applying the given search
4531 +     * function on each entry, or null if none.  Upon success,
4532 +     * further element processing is suppressed and the results of
4533 +     * any other parallel invocations of the search function are
4534 +     * ignored.
4535 +     *
4536 +     * @param searchFunction a function returning a non-null
4537 +     * result on success, else null
4538 +     * @return a non-null result from applying the given search
4539 +     * function on each entry, or null if none
4540 +     */
4541 +    public <U> U searchEntriesInParallel
4542 +        (Function<Map.Entry<K,V>, ? extends U> searchFunction) {
4543 +        return ForkJoinTasks.searchEntries
4544 +            (this, searchFunction).invoke();
4545 +    }
4546 +
4547 +    /**
4548 +     * Returns the result of accumulating all entries using the
4549 +     * given reducer to combine values, or null if none.
4550 +     *
4551 +     * @param reducer a commutative associative combining function
4552 +     * @return the result of accumulating all entries
4553 +     */
4554 +    public Map.Entry<K,V> reduceEntriesInParallel
4555 +        (BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4556 +        return ForkJoinTasks.reduceEntries
4557 +            (this, reducer).invoke();
4558 +    }
4559 +
4560 +    /**
4561 +     * Returns the result of accumulating the given transformation
4562 +     * of all entries using the given reducer to combine values,
4563 +     * or null if none.
4564 +     *
4565 +     * @param transformer a function returning the transformation
4566 +     * for an element, or null if there is no transformation (in
4567 +     * which case it is not combined)
4568 +     * @param reducer a commutative associative combining function
4569 +     * @return the result of accumulating the given transformation
4570 +     * of all entries
4571 +     */
4572 +    public <U> U reduceEntriesInParallel
4573 +        (Function<Map.Entry<K,V>, ? extends U> transformer,
4574 +         BiFunction<? super U, ? super U, ? extends U> reducer) {
4575 +        return ForkJoinTasks.reduceEntries
4576 +            (this, transformer, reducer).invoke();
4577 +    }
4578 +
4579 +    /**
4580 +     * Returns the result of accumulating the given transformation
4581 +     * of all entries using the given reducer to combine values,
4582 +     * and the given basis as an identity value.
4583 +     *
4584 +     * @param transformer a function returning the transformation
4585 +     * for an element
4586 +     * @param basis the identity (initial default value) for the reduction
4587 +     * @param reducer a commutative associative combining function
4588 +     * @return the result of accumulating the given transformation
4589 +     * of all entries
4590 +     */
4591 +    public double reduceEntriesToDoubleInParallel
4592 +        (ToDoubleFunction<Map.Entry<K,V>> transformer,
4593 +         double basis,
4594 +         DoubleBinaryOperator reducer) {
4595 +        return ForkJoinTasks.reduceEntriesToDouble
4596 +            (this, transformer, basis, reducer).invoke();
4597      }
4598  
4599 <    private class EntrySet extends AbstractSet<Map.Entry<K,V>> {
4600 <        public Iterator<Map.Entry<K,V>> iterator() {
4601 <            return new EntryIterator();
4599 >    /**
4600 >     * Returns the result of accumulating the given transformation
4601 >     * of all entries using the given reducer to combine values,
4602 >     * and the given basis as an identity value.
4603 >     *
4604 >     * @param transformer a function returning the transformation
4605 >     * for an element
4606 >     * @param basis the identity (initial default value) for the reduction
4607 >     * @param reducer a commutative associative combining function
4608 >     * @return the result of accumulating the given transformation
4609 >     * of all entries
4610 >     */
4611 >    public long reduceEntriesToLongInParallel
4612 >        (ToLongFunction<Map.Entry<K,V>> transformer,
4613 >         long basis,
4614 >         LongBinaryOperator reducer) {
4615 >        return ForkJoinTasks.reduceEntriesToLong
4616 >            (this, transformer, basis, reducer).invoke();
4617 >    }
4618 >
4619 >    /**
4620 >     * Returns the result of accumulating the given transformation
4621 >     * of all entries using the given reducer to combine values,
4622 >     * and the given basis as an identity value.
4623 >     *
4624 >     * @param transformer a function returning the transformation
4625 >     * for an element
4626 >     * @param basis the identity (initial default value) for the reduction
4627 >     * @param reducer a commutative associative combining function
4628 >     * @return the result of accumulating the given transformation
4629 >     * of all entries
4630 >     */
4631 >    public int reduceEntriesToIntInParallel
4632 >        (ToIntFunction<Map.Entry<K,V>> transformer,
4633 >         int basis,
4634 >         IntBinaryOperator reducer) {
4635 >        return ForkJoinTasks.reduceEntriesToInt
4636 >            (this, transformer, basis, reducer).invoke();
4637 >    }
4638 >
4639 >
4640 >    /* ----------------Views -------------- */
4641 >
4642 >    /**
4643 >     * Base class for views.
4644 >     */
4645 >    abstract static class CHMCollectionView<K,V,E>
4646 >            implements Collection<E>, java.io.Serializable {
4647 >        private static final long serialVersionUID = 7249069246763182397L;
4648 >        final ConcurrentHashMap<K,V> map;
4649 >        CHMCollectionView(ConcurrentHashMap<K,V> map)  { this.map = map; }
4650 >
4651 >        /**
4652 >         * Returns the map backing this view.
4653 >         *
4654 >         * @return the map backing this view
4655 >         */
4656 >        public ConcurrentHashMap<K,V> getMap() { return map; }
4657 >
4658 >        /**
4659 >         * Removes all of the elements from this view, by removing all
4660 >         * the mappings from the map backing this view.
4661 >         */
4662 >        public final void clear()      { map.clear(); }
4663 >        public final int size()        { return map.size(); }
4664 >        public final boolean isEmpty() { return map.isEmpty(); }
4665 >
4666 >        // implementations below rely on concrete classes supplying these
4667 >        // abstract methods
4668 >        /**
4669 >         * Returns a "weakly consistent" iterator that will never
4670 >         * throw {@link ConcurrentModificationException}, and
4671 >         * guarantees to traverse elements as they existed upon
4672 >         * construction of the iterator, and may (but is not
4673 >         * guaranteed to) reflect any modifications subsequent to
4674 >         * construction.
4675 >         */
4676 >        public abstract Iterator<E> iterator();
4677 >        public abstract boolean contains(Object o);
4678 >        public abstract boolean remove(Object o);
4679 >
4680 >        private static final String oomeMsg = "Required array size too large";
4681 >
4682 >        public final Object[] toArray() {
4683 >            long sz = map.mappingCount();
4684 >            if (sz > MAX_ARRAY_SIZE)
4685 >                throw new OutOfMemoryError(oomeMsg);
4686 >            int n = (int)sz;
4687 >            Object[] r = new Object[n];
4688 >            int i = 0;
4689 >            for (E e : this) {
4690 >                if (i == n) {
4691 >                    if (n >= MAX_ARRAY_SIZE)
4692 >                        throw new OutOfMemoryError(oomeMsg);
4693 >                    if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4694 >                        n = MAX_ARRAY_SIZE;
4695 >                    else
4696 >                        n += (n >>> 1) + 1;
4697 >                    r = Arrays.copyOf(r, n);
4698 >                }
4699 >                r[i++] = e;
4700 >            }
4701 >            return (i == n) ? r : Arrays.copyOf(r, i);
4702          }
4703 <        public boolean contains(Object o) {
4704 <            if (!(o instanceof Map.Entry))
4705 <                return false;
4706 <            Map.Entry<K,V> e = (Map.Entry<K,V>)o;
4707 <            V v = ConcurrentHashMap.this.get(e.getKey());
4708 <            return v != null && v.equals(e.getValue());
4703 >
4704 >        @SuppressWarnings("unchecked")
4705 >        public final <T> T[] toArray(T[] a) {
4706 >            long sz = map.mappingCount();
4707 >            if (sz > MAX_ARRAY_SIZE)
4708 >                throw new OutOfMemoryError(oomeMsg);
4709 >            int m = (int)sz;
4710 >            T[] r = (a.length >= m) ? a :
4711 >                (T[])java.lang.reflect.Array
4712 >                .newInstance(a.getClass().getComponentType(), m);
4713 >            int n = r.length;
4714 >            int i = 0;
4715 >            for (E e : this) {
4716 >                if (i == n) {
4717 >                    if (n >= MAX_ARRAY_SIZE)
4718 >                        throw new OutOfMemoryError(oomeMsg);
4719 >                    if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4720 >                        n = MAX_ARRAY_SIZE;
4721 >                    else
4722 >                        n += (n >>> 1) + 1;
4723 >                    r = Arrays.copyOf(r, n);
4724 >                }
4725 >                r[i++] = (T)e;
4726 >            }
4727 >            if (a == r && i < n) {
4728 >                r[i] = null; // null-terminate
4729 >                return r;
4730 >            }
4731 >            return (i == n) ? r : Arrays.copyOf(r, i);
4732          }
4733 <        public boolean remove(Object o) {
4734 <            if (!(o instanceof Map.Entry))
4735 <                return false;
4736 <            Map.Entry<K,V> e = (Map.Entry<K,V>)o;
4737 <            return ConcurrentHashMap.this.remove(e.getKey(), e.getValue());
4733 >
4734 >        /**
4735 >         * Returns a string representation of this collection.
4736 >         * The string representation consists of the string representations
4737 >         * of the collection's elements in the order they are returned by
4738 >         * its iterator, enclosed in square brackets ({@code "[]"}).
4739 >         * Adjacent elements are separated by the characters {@code ", "}
4740 >         * (comma and space).  Elements are converted to strings as by
4741 >         * {@link String#valueOf(Object)}.
4742 >         *
4743 >         * @return a string representation of this collection
4744 >         */
4745 >        public final String toString() {
4746 >            StringBuilder sb = new StringBuilder();
4747 >            sb.append('[');
4748 >            Iterator<E> it = iterator();
4749 >            if (it.hasNext()) {
4750 >                for (;;) {
4751 >                    Object e = it.next();
4752 >                    sb.append(e == this ? "(this Collection)" : e);
4753 >                    if (!it.hasNext())
4754 >                        break;
4755 >                    sb.append(',').append(' ');
4756 >                }
4757 >            }
4758 >            return sb.append(']').toString();
4759          }
4760 <        public int size() {
4761 <            return ConcurrentHashMap.this.size();
4760 >
4761 >        public final boolean containsAll(Collection<?> c) {
4762 >            if (c != this) {
4763 >                for (Object e : c) {
4764 >                    if (e == null || !contains(e))
4765 >                        return false;
4766 >                }
4767 >            }
4768 >            return true;
4769          }
4770 <        public void clear() {
4771 <            ConcurrentHashMap.this.clear();
4770 >
4771 >        public final boolean removeAll(Collection<?> c) {
4772 >            boolean modified = false;
4773 >            for (Iterator<E> it = iterator(); it.hasNext();) {
4774 >                if (c.contains(it.next())) {
4775 >                    it.remove();
4776 >                    modified = true;
4777 >                }
4778 >            }
4779 >            return modified;
4780          }
4781 +
4782 +        public final boolean retainAll(Collection<?> c) {
4783 +            boolean modified = false;
4784 +            for (Iterator<E> it = iterator(); it.hasNext();) {
4785 +                if (!c.contains(it.next())) {
4786 +                    it.remove();
4787 +                    modified = true;
4788 +                }
4789 +            }
4790 +            return modified;
4791 +        }
4792 +
4793      }
4794  
4795 <    /* ---------------- Serialization Support -------------- */
4795 >    abstract static class CHMSetView<K,V,E>
4796 >            extends CHMCollectionView<K,V,E>
4797 >            implements Set<E>, java.io.Serializable {
4798 >        private static final long serialVersionUID = 7249069246763182397L;
4799 >        CHMSetView(ConcurrentHashMap<K,V> map) { super(map); }
4800 >
4801 >        // Implement Set API
4802 >
4803 >        /**
4804 >         * Implements {@link Set#hashCode()}.
4805 >         * @return the hash code value for this set
4806 >         */
4807 >        public final int hashCode() {
4808 >            int h = 0;
4809 >            for (E e : this)
4810 >                h += e.hashCode();
4811 >            return h;
4812 >        }
4813 >
4814 >        /**
4815 >         * Implements {@link Set#equals(Object)}.
4816 >         * @param o object to be compared for equality with this set
4817 >         * @return {@code true} if the specified object is equal to this set
4818 >        */
4819 >        public final boolean equals(Object o) {
4820 >            Set<?> c;
4821 >            return ((o instanceof Set) &&
4822 >                    ((c = (Set<?>)o) == this ||
4823 >                     (containsAll(c) && c.containsAll(this))));
4824 >        }
4825 >    }
4826  
4827      /**
4828 <     * Save the state of the <tt>ConcurrentHashMap</tt>
4829 <     * instance to a stream (i.e.,
4830 <     * serialize it).
4831 <     * @param s the stream
4832 <     * @serialData
4833 <     * the key (Object) and value (Object)
4834 <     * for each key-value mapping, followed by a null pair.
1084 <     * The key-value mappings are emitted in no particular order.
4828 >     * A view of a ConcurrentHashMap as a {@link Set} of keys, in
4829 >     * which additions may optionally be enabled by mapping to a
4830 >     * common value.  This class cannot be directly instantiated.
4831 >     * See {@link #keySet() keySet()},
4832 >     * {@link #keySet(Object) keySet(V)},
4833 >     * {@link #newKeySet() newKeySet()},
4834 >     * {@link #newKeySet(int) newKeySet(int)}.
4835       */
4836 <    private void writeObject(java.io.ObjectOutputStream s) throws IOException  {
4837 <        s.defaultWriteObject();
4836 >    public static class KeySetView<K,V>
4837 >            extends CHMSetView<K,V,K>
4838 >            implements Set<K>, java.io.Serializable {
4839 >        private static final long serialVersionUID = 7249069246763182397L;
4840 >        private final V value;
4841 >        KeySetView(ConcurrentHashMap<K,V> map, V value) {  // non-public
4842 >            super(map);
4843 >            this.value = value;
4844 >        }
4845  
4846 <        for (int k = 0; k < segments.length; ++k) {
4847 <            Segment<K,V> seg = (Segment<K,V>)segments[k];
4848 <            seg.lock();
4849 <            try {
4850 <                HashEntry[] tab = seg.table;
4851 <                for (int i = 0; i < tab.length; ++i) {
4852 <                    for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i]; e != null; e = e.next) {
4853 <                        s.writeObject(e.key);
4854 <                        s.writeObject(e.value);
4846 >        /**
4847 >         * Returns the default mapped value for additions,
4848 >         * or {@code null} if additions are not supported.
4849 >         *
4850 >         * @return the default mapped value for additions, or {@code null}
4851 >         * if not supported
4852 >         */
4853 >        public V getMappedValue() { return value; }
4854 >
4855 >        /**
4856 >         * {@inheritDoc}
4857 >         * @throws NullPointerException if the specified key is null
4858 >         */
4859 >        public boolean contains(Object o) { return map.containsKey(o); }
4860 >
4861 >        /**
4862 >         * Removes the key from this map view, by removing the key (and its
4863 >         * corresponding value) from the backing map.  This method does
4864 >         * nothing if the key is not in the map.
4865 >         *
4866 >         * @param  o the key to be removed from the backing map
4867 >         * @return {@code true} if the backing map contained the specified key
4868 >         * @throws NullPointerException if the specified key is null
4869 >         */
4870 >        public boolean remove(Object o) { return map.remove(o) != null; }
4871 >
4872 >        /**
4873 >         * @return an iterator over the keys of the backing map
4874 >         */
4875 >        public Iterator<K> iterator() { return new KeyIterator<K,V>(map); }
4876 >
4877 >        /**
4878 >         * Adds the specified key to this set view by mapping the key to
4879 >         * the default mapped value in the backing map, if defined.
4880 >         *
4881 >         * @param e key to be added
4882 >         * @return {@code true} if this set changed as a result of the call
4883 >         * @throws NullPointerException if the specified key is null
4884 >         * @throws UnsupportedOperationException if no default mapped value
4885 >         * for additions was provided
4886 >         */
4887 >        public boolean add(K e) {
4888 >            V v;
4889 >            if ((v = value) == null)
4890 >                throw new UnsupportedOperationException();
4891 >            return map.internalPut(e, v, true) == null;
4892 >        }
4893 >
4894 >        /**
4895 >         * Adds all of the elements in the specified collection to this set,
4896 >         * as if by calling {@link #add} on each one.
4897 >         *
4898 >         * @param c the elements to be inserted into this set
4899 >         * @return {@code true} if this set changed as a result of the call
4900 >         * @throws NullPointerException if the collection or any of its
4901 >         * elements are {@code null}
4902 >         * @throws UnsupportedOperationException if no default mapped value
4903 >         * for additions was provided
4904 >         */
4905 >        public boolean addAll(Collection<? extends K> c) {
4906 >            boolean added = false;
4907 >            V v;
4908 >            if ((v = value) == null)
4909 >                throw new UnsupportedOperationException();
4910 >            for (K e : c) {
4911 >                if (map.internalPut(e, v, true) == null)
4912 >                    added = true;
4913 >            }
4914 >            return added;
4915 >        }
4916 >
4917 >        public Spliterator<K> spliterator() {
4918 >            return new KeyIterator<>(map, null);
4919 >        }
4920 >
4921 >    }
4922 >
4923 >    /**
4924 >     * A view of a ConcurrentHashMap as a {@link Collection} of
4925 >     * values, in which additions are disabled. This class cannot be
4926 >     * directly instantiated. See {@link #values()}.
4927 >     *
4928 >     * <p>The view's {@code iterator} is a "weakly consistent" iterator
4929 >     * that will never throw {@link ConcurrentModificationException},
4930 >     * and guarantees to traverse elements as they existed upon
4931 >     * construction of the iterator, and may (but is not guaranteed to)
4932 >     * reflect any modifications subsequent to construction.
4933 >     */
4934 >    public static final class ValuesView<K,V>
4935 >            extends CHMCollectionView<K,V,V>
4936 >            implements Collection<V>, java.io.Serializable {
4937 >        private static final long serialVersionUID = 2249069246763182397L;
4938 >        ValuesView(ConcurrentHashMap<K,V> map) { super(map); }
4939 >        public final boolean contains(Object o) {
4940 >            return map.containsValue(o);
4941 >        }
4942 >        public final boolean remove(Object o) {
4943 >            if (o != null) {
4944 >                for (Iterator<V> it = iterator(); it.hasNext();) {
4945 >                    if (o.equals(it.next())) {
4946 >                        it.remove();
4947 >                        return true;
4948                      }
4949                  }
1100            } finally {
1101                seg.unlock();
4950              }
4951 +            return false;
4952          }
4953 <        s.writeObject(null);
4954 <        s.writeObject(null);
4953 >
4954 >        /**
4955 >         * @return an iterator over the values of the backing map
4956 >         */
4957 >        public final Iterator<V> iterator() {
4958 >            return new ValueIterator<K,V>(map);
4959 >        }
4960 >
4961 >        /** Always throws {@link UnsupportedOperationException}. */
4962 >        public final boolean add(V e) {
4963 >            throw new UnsupportedOperationException();
4964 >        }
4965 >        /** Always throws {@link UnsupportedOperationException}. */
4966 >        public final boolean addAll(Collection<? extends V> c) {
4967 >            throw new UnsupportedOperationException();
4968 >        }
4969 >
4970 >        public Spliterator<V> spliterator() {
4971 >            return new ValueIterator<K,V>(map, null);
4972 >        }
4973 >
4974      }
4975  
4976      /**
4977 <     * Reconstitute the <tt>ConcurrentHashMap</tt>
4978 <     * instance from a stream (i.e.,
4979 <     * deserialize it).
1112 <     * @param s the stream
4977 >     * A view of a ConcurrentHashMap as a {@link Set} of (key, value)
4978 >     * entries.  This class cannot be directly instantiated. See
4979 >     * {@link #entrySet()}.
4980       */
4981 <    private void readObject(java.io.ObjectInputStream s)
4982 <        throws IOException, ClassNotFoundException  {
4983 <        s.defaultReadObject();
4981 >    public static final class EntrySetView<K,V>
4982 >            extends CHMSetView<K,V,Map.Entry<K,V>>
4983 >            implements Set<Map.Entry<K,V>>, java.io.Serializable {
4984 >        private static final long serialVersionUID = 2249069246763182397L;
4985 >        EntrySetView(ConcurrentHashMap<K,V> map) { super(map); }
4986  
4987 <        // Initialize each segment to be minimally sized, and let grow.
4988 <        for (int i = 0; i < segments.length; ++i) {
4989 <            segments[i].setTable(new HashEntry[1]);
4987 >        public final boolean contains(Object o) {
4988 >            Object k, v, r; Map.Entry<?,?> e;
4989 >            return ((o instanceof Map.Entry) &&
4990 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4991 >                    (r = map.get(k)) != null &&
4992 >                    (v = e.getValue()) != null &&
4993 >                    (v == r || v.equals(r)));
4994 >        }
4995 >        public final boolean remove(Object o) {
4996 >            Object k, v; Map.Entry<?,?> e;
4997 >            return ((o instanceof Map.Entry) &&
4998 >                    (k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4999 >                    (v = e.getValue()) != null &&
5000 >                    map.remove(k, v));
5001          }
5002  
5003 <        // Read the keys and values, and put the mappings in the table
5004 <        for (;;) {
5005 <            K key = (K) s.readObject();
5006 <            V value = (V) s.readObject();
5007 <            if (key == null)
5008 <                break;
5009 <            put(key, value);
5003 >        /**
5004 >         * @return an iterator over the entries of the backing map
5005 >         */
5006 >        public final Iterator<Map.Entry<K,V>> iterator() {
5007 >            return new EntryIterator<K,V>(map);
5008 >        }
5009 >
5010 >        /**
5011 >         * Adds the specified mapping to this view.
5012 >         *
5013 >         * @param e mapping to be added
5014 >         * @return {@code true} if this set changed as a result of the call
5015 >         * @throws NullPointerException if the entry, its key, or its
5016 >         * value is null
5017 >         */
5018 >        public final boolean add(Entry<K,V> e) {
5019 >            return map.internalPut(e.getKey(), e.getValue(), false) == null;
5020 >        }
5021 >
5022 >        /**
5023 >         * Adds all of the mappings in the specified collection to this
5024 >         * set, as if by calling {@link #add(Map.Entry)} on each one.
5025 >         * @param c the mappings to be inserted into this set
5026 >         * @return {@code true} if this set changed as a result of the call
5027 >         * @throws NullPointerException if the collection or any of its
5028 >         * entries, keys, or values are null
5029 >         */
5030 >        public final boolean addAll(Collection<? extends Entry<K,V>> c) {
5031 >            boolean added = false;
5032 >            for (Entry<K,V> e : c) {
5033 >                if (add(e))
5034 >                    added = true;
5035 >            }
5036 >            return added;
5037 >        }
5038 >
5039 >        public Spliterator<Map.Entry<K,V>> spliterator() {
5040 >            return new EntryIterator<K,V>(map, null);
5041          }
5042 +
5043      }
1132 }
5044  
5045 +    // ---------------------------------------------------------------------
5046 +
5047 +    /**
5048 +     * Predefined tasks for performing bulk parallel operations on
5049 +     * ConcurrentHashMaps. These tasks follow the forms and rules used
5050 +     * for bulk operations. Each method has the same name, but returns
5051 +     * a task rather than invoking it. These methods may be useful in
5052 +     * custom applications such as submitting a task without waiting
5053 +     * for completion, using a custom pool, or combining with other
5054 +     * tasks.
5055 +     */
5056 +    public static class ForkJoinTasks {
5057 +        private ForkJoinTasks() {}
5058 +
5059 +        /**
5060 +         * Returns a task that when invoked, performs the given
5061 +         * action for each (key, value)
5062 +         *
5063 +         * @param map the map
5064 +         * @param action the action
5065 +         * @return the task
5066 +         */
5067 +        public static <K,V> ForkJoinTask<Void> forEach
5068 +            (ConcurrentHashMap<K,V> map,
5069 +             BiConsumer<? super K, ? super V> action) {
5070 +            if (action == null) throw new NullPointerException();
5071 +            return new ForEachMappingTask<K,V>(map, null, -1, action);
5072 +        }
5073 +
5074 +        /**
5075 +         * Returns a task that when invoked, performs the given
5076 +         * action for each non-null transformation of each (key, value)
5077 +         *
5078 +         * @param map the map
5079 +         * @param transformer a function returning the transformation
5080 +         * for an element, or null if there is no transformation (in
5081 +         * which case the action is not applied)
5082 +         * @param action the action
5083 +         * @return the task
5084 +         */
5085 +        public static <K,V,U> ForkJoinTask<Void> forEach
5086 +            (ConcurrentHashMap<K,V> map,
5087 +             BiFunction<? super K, ? super V, ? extends U> transformer,
5088 +             Consumer<? super U> action) {
5089 +            if (transformer == null || action == null)
5090 +                throw new NullPointerException();
5091 +            return new ForEachTransformedMappingTask<K,V,U>
5092 +                (map, null, -1, transformer, action);
5093 +        }
5094 +
5095 +        /**
5096 +         * Returns a task that when invoked, returns a non-null result
5097 +         * from applying the given search function on each (key,
5098 +         * value), or null if none. Upon success, further element
5099 +         * processing is suppressed and the results of any other
5100 +         * parallel invocations of the search function are ignored.
5101 +         *
5102 +         * @param map the map
5103 +         * @param searchFunction a function returning a non-null
5104 +         * result on success, else null
5105 +         * @return the task
5106 +         */
5107 +        public static <K,V,U> ForkJoinTask<U> search
5108 +            (ConcurrentHashMap<K,V> map,
5109 +             BiFunction<? super K, ? super V, ? extends U> searchFunction) {
5110 +            if (searchFunction == null) throw new NullPointerException();
5111 +            return new SearchMappingsTask<K,V,U>
5112 +                (map, null, -1, searchFunction,
5113 +                 new AtomicReference<U>());
5114 +        }
5115 +
5116 +        /**
5117 +         * Returns a task that when invoked, returns the result of
5118 +         * accumulating the given transformation of all (key, value) pairs
5119 +         * using the given reducer to combine values, or null if none.
5120 +         *
5121 +         * @param map the map
5122 +         * @param transformer a function returning the transformation
5123 +         * for an element, or null if there is no transformation (in
5124 +         * which case it is not combined)
5125 +         * @param reducer a commutative associative combining function
5126 +         * @return the task
5127 +         */
5128 +        public static <K,V,U> ForkJoinTask<U> reduce
5129 +            (ConcurrentHashMap<K,V> map,
5130 +             BiFunction<? super K, ? super V, ? extends U> transformer,
5131 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
5132 +            if (transformer == null || reducer == null)
5133 +                throw new NullPointerException();
5134 +            return new MapReduceMappingsTask<K,V,U>
5135 +                (map, null, -1, null, transformer, reducer);
5136 +        }
5137 +
5138 +        /**
5139 +         * Returns a task that when invoked, returns the result of
5140 +         * accumulating the given transformation of all (key, value) pairs
5141 +         * using the given reducer to combine values, and the given
5142 +         * basis as an identity value.
5143 +         *
5144 +         * @param map the map
5145 +         * @param transformer a function returning the transformation
5146 +         * for an element
5147 +         * @param basis the identity (initial default value) for the reduction
5148 +         * @param reducer a commutative associative combining function
5149 +         * @return the task
5150 +         */
5151 +        public static <K,V> ForkJoinTask<Double> reduceToDouble
5152 +            (ConcurrentHashMap<K,V> map,
5153 +             ToDoubleBiFunction<? super K, ? super V> transformer,
5154 +             double basis,
5155 +             DoubleBinaryOperator reducer) {
5156 +            if (transformer == null || reducer == null)
5157 +                throw new NullPointerException();
5158 +            return new MapReduceMappingsToDoubleTask<K,V>
5159 +                (map, null, -1, null, transformer, basis, reducer);
5160 +        }
5161 +
5162 +        /**
5163 +         * Returns a task that when invoked, returns the result of
5164 +         * accumulating the given transformation of all (key, value) pairs
5165 +         * using the given reducer to combine values, and the given
5166 +         * basis as an identity value.
5167 +         *
5168 +         * @param map the map
5169 +         * @param transformer a function returning the transformation
5170 +         * for an element
5171 +         * @param basis the identity (initial default value) for the reduction
5172 +         * @param reducer a commutative associative combining function
5173 +         * @return the task
5174 +         */
5175 +        public static <K,V> ForkJoinTask<Long> reduceToLong
5176 +            (ConcurrentHashMap<K,V> map,
5177 +             ToLongBiFunction<? super K, ? super V> transformer,
5178 +             long basis,
5179 +             LongBinaryOperator reducer) {
5180 +            if (transformer == null || reducer == null)
5181 +                throw new NullPointerException();
5182 +            return new MapReduceMappingsToLongTask<K,V>
5183 +                (map, null, -1, null, transformer, basis, reducer);
5184 +        }
5185 +
5186 +        /**
5187 +         * Returns a task that when invoked, returns the result of
5188 +         * accumulating the given transformation of all (key, value) pairs
5189 +         * using the given reducer to combine values, and the given
5190 +         * basis as an identity value.
5191 +         *
5192 +         * @param map the map
5193 +         * @param transformer a function returning the transformation
5194 +         * for an element
5195 +         * @param basis the identity (initial default value) for the reduction
5196 +         * @param reducer a commutative associative combining function
5197 +         * @return the task
5198 +         */
5199 +        public static <K,V> ForkJoinTask<Integer> reduceToInt
5200 +            (ConcurrentHashMap<K,V> map,
5201 +             ToIntBiFunction<? super K, ? super V> transformer,
5202 +             int basis,
5203 +             IntBinaryOperator reducer) {
5204 +            if (transformer == null || reducer == null)
5205 +                throw new NullPointerException();
5206 +            return new MapReduceMappingsToIntTask<K,V>
5207 +                (map, null, -1, null, transformer, basis, reducer);
5208 +        }
5209 +
5210 +        /**
5211 +         * Returns a task that when invoked, performs the given action
5212 +         * for each key.
5213 +         *
5214 +         * @param map the map
5215 +         * @param action the action
5216 +         * @return the task
5217 +         */
5218 +        public static <K,V> ForkJoinTask<Void> forEachKey
5219 +            (ConcurrentHashMap<K,V> map,
5220 +             Consumer<? super K> action) {
5221 +            if (action == null) throw new NullPointerException();
5222 +            return new ForEachKeyTask<K,V>(map, null, -1, action);
5223 +        }
5224 +
5225 +        /**
5226 +         * Returns a task that when invoked, performs the given action
5227 +         * for each non-null transformation of each key.
5228 +         *
5229 +         * @param map the map
5230 +         * @param transformer a function returning the transformation
5231 +         * for an element, or null if there is no transformation (in
5232 +         * which case the action is not applied)
5233 +         * @param action the action
5234 +         * @return the task
5235 +         */
5236 +        public static <K,V,U> ForkJoinTask<Void> forEachKey
5237 +            (ConcurrentHashMap<K,V> map,
5238 +             Function<? super K, ? extends U> transformer,
5239 +             Consumer<? super U> action) {
5240 +            if (transformer == null || action == null)
5241 +                throw new NullPointerException();
5242 +            return new ForEachTransformedKeyTask<K,V,U>
5243 +                (map, null, -1, transformer, action);
5244 +        }
5245 +
5246 +        /**
5247 +         * Returns a task that when invoked, returns a non-null result
5248 +         * from applying the given search function on each key, or
5249 +         * null if none.  Upon success, further element processing is
5250 +         * suppressed and the results of any other parallel
5251 +         * invocations of the search function are ignored.
5252 +         *
5253 +         * @param map the map
5254 +         * @param searchFunction a function returning a non-null
5255 +         * result on success, else null
5256 +         * @return the task
5257 +         */
5258 +        public static <K,V,U> ForkJoinTask<U> searchKeys
5259 +            (ConcurrentHashMap<K,V> map,
5260 +             Function<? super K, ? extends U> searchFunction) {
5261 +            if (searchFunction == null) throw new NullPointerException();
5262 +            return new SearchKeysTask<K,V,U>
5263 +                (map, null, -1, searchFunction,
5264 +                 new AtomicReference<U>());
5265 +        }
5266 +
5267 +        /**
5268 +         * Returns a task that when invoked, returns the result of
5269 +         * accumulating all keys using the given reducer to combine
5270 +         * values, or null if none.
5271 +         *
5272 +         * @param map the map
5273 +         * @param reducer a commutative associative combining function
5274 +         * @return the task
5275 +         */
5276 +        public static <K,V> ForkJoinTask<K> reduceKeys
5277 +            (ConcurrentHashMap<K,V> map,
5278 +             BiFunction<? super K, ? super K, ? extends K> reducer) {
5279 +            if (reducer == null) throw new NullPointerException();
5280 +            return new ReduceKeysTask<K,V>
5281 +                (map, null, -1, null, reducer);
5282 +        }
5283 +
5284 +        /**
5285 +         * Returns a task that when invoked, returns the result of
5286 +         * accumulating the given transformation of all keys using the given
5287 +         * reducer to combine values, or null if none.
5288 +         *
5289 +         * @param map the map
5290 +         * @param transformer a function returning the transformation
5291 +         * for an element, or null if there is no transformation (in
5292 +         * which case it is not combined)
5293 +         * @param reducer a commutative associative combining function
5294 +         * @return the task
5295 +         */
5296 +        public static <K,V,U> ForkJoinTask<U> reduceKeys
5297 +            (ConcurrentHashMap<K,V> map,
5298 +             Function<? super K, ? extends U> transformer,
5299 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
5300 +            if (transformer == null || reducer == null)
5301 +                throw new NullPointerException();
5302 +            return new MapReduceKeysTask<K,V,U>
5303 +                (map, null, -1, null, transformer, reducer);
5304 +        }
5305 +
5306 +        /**
5307 +         * Returns a task that when invoked, returns the result of
5308 +         * accumulating the given transformation of all keys using the given
5309 +         * reducer to combine values, and the given basis as an
5310 +         * identity value.
5311 +         *
5312 +         * @param map the map
5313 +         * @param transformer a function returning the transformation
5314 +         * for an element
5315 +         * @param basis the identity (initial default value) for the reduction
5316 +         * @param reducer a commutative associative combining function
5317 +         * @return the task
5318 +         */
5319 +        public static <K,V> ForkJoinTask<Double> reduceKeysToDouble
5320 +            (ConcurrentHashMap<K,V> map,
5321 +             ToDoubleFunction<? super K> transformer,
5322 +             double basis,
5323 +             DoubleBinaryOperator reducer) {
5324 +            if (transformer == null || reducer == null)
5325 +                throw new NullPointerException();
5326 +            return new MapReduceKeysToDoubleTask<K,V>
5327 +                (map, null, -1, null, transformer, basis, reducer);
5328 +        }
5329 +
5330 +        /**
5331 +         * Returns a task that when invoked, returns the result of
5332 +         * accumulating the given transformation of all keys using the given
5333 +         * reducer to combine values, and the given basis as an
5334 +         * identity value.
5335 +         *
5336 +         * @param map the map
5337 +         * @param transformer a function returning the transformation
5338 +         * for an element
5339 +         * @param basis the identity (initial default value) for the reduction
5340 +         * @param reducer a commutative associative combining function
5341 +         * @return the task
5342 +         */
5343 +        public static <K,V> ForkJoinTask<Long> reduceKeysToLong
5344 +            (ConcurrentHashMap<K,V> map,
5345 +             ToLongFunction<? super K> transformer,
5346 +             long basis,
5347 +             LongBinaryOperator reducer) {
5348 +            if (transformer == null || reducer == null)
5349 +                throw new NullPointerException();
5350 +            return new MapReduceKeysToLongTask<K,V>
5351 +                (map, null, -1, null, transformer, basis, reducer);
5352 +        }
5353 +
5354 +        /**
5355 +         * Returns a task that when invoked, returns the result of
5356 +         * accumulating the given transformation of all keys using the given
5357 +         * reducer to combine values, and the given basis as an
5358 +         * identity value.
5359 +         *
5360 +         * @param map the map
5361 +         * @param transformer a function returning the transformation
5362 +         * for an element
5363 +         * @param basis the identity (initial default value) for the reduction
5364 +         * @param reducer a commutative associative combining function
5365 +         * @return the task
5366 +         */
5367 +        public static <K,V> ForkJoinTask<Integer> reduceKeysToInt
5368 +            (ConcurrentHashMap<K,V> map,
5369 +             ToIntFunction<? super K> transformer,
5370 +             int basis,
5371 +             IntBinaryOperator reducer) {
5372 +            if (transformer == null || reducer == null)
5373 +                throw new NullPointerException();
5374 +            return new MapReduceKeysToIntTask<K,V>
5375 +                (map, null, -1, null, transformer, basis, reducer);
5376 +        }
5377 +
5378 +        /**
5379 +         * Returns a task that when invoked, performs the given action
5380 +         * for each value.
5381 +         *
5382 +         * @param map the map
5383 +         * @param action the action
5384 +         * @return the task
5385 +         */
5386 +        public static <K,V> ForkJoinTask<Void> forEachValue
5387 +            (ConcurrentHashMap<K,V> map,
5388 +             Consumer<? super V> action) {
5389 +            if (action == null) throw new NullPointerException();
5390 +            return new ForEachValueTask<K,V>(map, null, -1, action);
5391 +        }
5392 +
5393 +        /**
5394 +         * Returns a task that when invoked, performs the given action
5395 +         * for each non-null transformation of each value.
5396 +         *
5397 +         * @param map the map
5398 +         * @param transformer a function returning the transformation
5399 +         * for an element, or null if there is no transformation (in
5400 +         * which case the action is not applied)
5401 +         * @param action the action
5402 +         * @return the task
5403 +         */
5404 +        public static <K,V,U> ForkJoinTask<Void> forEachValue
5405 +            (ConcurrentHashMap<K,V> map,
5406 +             Function<? super V, ? extends U> transformer,
5407 +             Consumer<? super U> action) {
5408 +            if (transformer == null || action == null)
5409 +                throw new NullPointerException();
5410 +            return new ForEachTransformedValueTask<K,V,U>
5411 +                (map, null, -1, transformer, action);
5412 +        }
5413 +
5414 +        /**
5415 +         * Returns a task that when invoked, returns a non-null result
5416 +         * from applying the given search function on each value, or
5417 +         * null if none.  Upon success, further element processing is
5418 +         * suppressed and the results of any other parallel
5419 +         * invocations of the search function are ignored.
5420 +         *
5421 +         * @param map the map
5422 +         * @param searchFunction a function returning a non-null
5423 +         * result on success, else null
5424 +         * @return the task
5425 +         */
5426 +        public static <K,V,U> ForkJoinTask<U> searchValues
5427 +            (ConcurrentHashMap<K,V> map,
5428 +             Function<? super V, ? extends U> searchFunction) {
5429 +            if (searchFunction == null) throw new NullPointerException();
5430 +            return new SearchValuesTask<K,V,U>
5431 +                (map, null, -1, searchFunction,
5432 +                 new AtomicReference<U>());
5433 +        }
5434 +
5435 +        /**
5436 +         * Returns a task that when invoked, returns the result of
5437 +         * accumulating all values using the given reducer to combine
5438 +         * values, or null if none.
5439 +         *
5440 +         * @param map the map
5441 +         * @param reducer a commutative associative combining function
5442 +         * @return the task
5443 +         */
5444 +        public static <K,V> ForkJoinTask<V> reduceValues
5445 +            (ConcurrentHashMap<K,V> map,
5446 +             BiFunction<? super V, ? super V, ? extends V> reducer) {
5447 +            if (reducer == null) throw new NullPointerException();
5448 +            return new ReduceValuesTask<K,V>
5449 +                (map, null, -1, null, reducer);
5450 +        }
5451 +
5452 +        /**
5453 +         * Returns a task that when invoked, returns the result of
5454 +         * accumulating the given transformation of all values using the
5455 +         * given reducer to combine values, or null if none.
5456 +         *
5457 +         * @param map the map
5458 +         * @param transformer a function returning the transformation
5459 +         * for an element, or null if there is no transformation (in
5460 +         * which case it is not combined)
5461 +         * @param reducer a commutative associative combining function
5462 +         * @return the task
5463 +         */
5464 +        public static <K,V,U> ForkJoinTask<U> reduceValues
5465 +            (ConcurrentHashMap<K,V> map,
5466 +             Function<? super V, ? extends U> transformer,
5467 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
5468 +            if (transformer == null || reducer == null)
5469 +                throw new NullPointerException();
5470 +            return new MapReduceValuesTask<K,V,U>
5471 +                (map, null, -1, null, transformer, reducer);
5472 +        }
5473 +
5474 +        /**
5475 +         * Returns a task that when invoked, returns the result of
5476 +         * accumulating the given transformation of all values using the
5477 +         * given reducer to combine values, and the given basis as an
5478 +         * identity value.
5479 +         *
5480 +         * @param map the map
5481 +         * @param transformer a function returning the transformation
5482 +         * for an element
5483 +         * @param basis the identity (initial default value) for the reduction
5484 +         * @param reducer a commutative associative combining function
5485 +         * @return the task
5486 +         */
5487 +        public static <K,V> ForkJoinTask<Double> reduceValuesToDouble
5488 +            (ConcurrentHashMap<K,V> map,
5489 +             ToDoubleFunction<? super V> transformer,
5490 +             double basis,
5491 +             DoubleBinaryOperator reducer) {
5492 +            if (transformer == null || reducer == null)
5493 +                throw new NullPointerException();
5494 +            return new MapReduceValuesToDoubleTask<K,V>
5495 +                (map, null, -1, null, transformer, basis, reducer);
5496 +        }
5497 +
5498 +        /**
5499 +         * Returns a task that when invoked, returns the result of
5500 +         * accumulating the given transformation of all values using the
5501 +         * given reducer to combine values, and the given basis as an
5502 +         * identity value.
5503 +         *
5504 +         * @param map the map
5505 +         * @param transformer a function returning the transformation
5506 +         * for an element
5507 +         * @param basis the identity (initial default value) for the reduction
5508 +         * @param reducer a commutative associative combining function
5509 +         * @return the task
5510 +         */
5511 +        public static <K,V> ForkJoinTask<Long> reduceValuesToLong
5512 +            (ConcurrentHashMap<K,V> map,
5513 +             ToLongFunction<? super V> transformer,
5514 +             long basis,
5515 +             LongBinaryOperator reducer) {
5516 +            if (transformer == null || reducer == null)
5517 +                throw new NullPointerException();
5518 +            return new MapReduceValuesToLongTask<K,V>
5519 +                (map, null, -1, null, transformer, basis, reducer);
5520 +        }
5521 +
5522 +        /**
5523 +         * Returns a task that when invoked, returns the result of
5524 +         * accumulating the given transformation of all values using the
5525 +         * given reducer to combine values, and the given basis as an
5526 +         * identity value.
5527 +         *
5528 +         * @param map the map
5529 +         * @param transformer a function returning the transformation
5530 +         * for an element
5531 +         * @param basis the identity (initial default value) for the reduction
5532 +         * @param reducer a commutative associative combining function
5533 +         * @return the task
5534 +         */
5535 +        public static <K,V> ForkJoinTask<Integer> reduceValuesToInt
5536 +            (ConcurrentHashMap<K,V> map,
5537 +             ToIntFunction<? super V> transformer,
5538 +             int basis,
5539 +             IntBinaryOperator reducer) {
5540 +            if (transformer == null || reducer == null)
5541 +                throw new NullPointerException();
5542 +            return new MapReduceValuesToIntTask<K,V>
5543 +                (map, null, -1, null, transformer, basis, reducer);
5544 +        }
5545 +
5546 +        /**
5547 +         * Returns a task that when invoked, perform the given action
5548 +         * for each entry.
5549 +         *
5550 +         * @param map the map
5551 +         * @param action the action
5552 +         * @return the task
5553 +         */
5554 +        public static <K,V> ForkJoinTask<Void> forEachEntry
5555 +            (ConcurrentHashMap<K,V> map,
5556 +             Consumer<? super Map.Entry<K,V>> action) {
5557 +            if (action == null) throw new NullPointerException();
5558 +            return new ForEachEntryTask<K,V>(map, null, -1, action);
5559 +        }
5560 +
5561 +        /**
5562 +         * Returns a task that when invoked, perform the given action
5563 +         * for each non-null transformation of each entry.
5564 +         *
5565 +         * @param map the map
5566 +         * @param transformer a function returning the transformation
5567 +         * for an element, or null if there is no transformation (in
5568 +         * which case the action is not applied)
5569 +         * @param action the action
5570 +         * @return the task
5571 +         */
5572 +        public static <K,V,U> ForkJoinTask<Void> forEachEntry
5573 +            (ConcurrentHashMap<K,V> map,
5574 +             Function<Map.Entry<K,V>, ? extends U> transformer,
5575 +             Consumer<? super U> action) {
5576 +            if (transformer == null || action == null)
5577 +                throw new NullPointerException();
5578 +            return new ForEachTransformedEntryTask<K,V,U>
5579 +                (map, null, -1, transformer, action);
5580 +        }
5581 +
5582 +        /**
5583 +         * Returns a task that when invoked, returns a non-null result
5584 +         * from applying the given search function on each entry, or
5585 +         * null if none.  Upon success, further element processing is
5586 +         * suppressed and the results of any other parallel
5587 +         * invocations of the search function are ignored.
5588 +         *
5589 +         * @param map the map
5590 +         * @param searchFunction a function returning a non-null
5591 +         * result on success, else null
5592 +         * @return the task
5593 +         */
5594 +        public static <K,V,U> ForkJoinTask<U> searchEntries
5595 +            (ConcurrentHashMap<K,V> map,
5596 +             Function<Map.Entry<K,V>, ? extends U> searchFunction) {
5597 +            if (searchFunction == null) throw new NullPointerException();
5598 +            return new SearchEntriesTask<K,V,U>
5599 +                (map, null, -1, searchFunction,
5600 +                 new AtomicReference<U>());
5601 +        }
5602 +
5603 +        /**
5604 +         * Returns a task that when invoked, returns the result of
5605 +         * accumulating all entries using the given reducer to combine
5606 +         * values, or null if none.
5607 +         *
5608 +         * @param map the map
5609 +         * @param reducer a commutative associative combining function
5610 +         * @return the task
5611 +         */
5612 +        public static <K,V> ForkJoinTask<Map.Entry<K,V>> reduceEntries
5613 +            (ConcurrentHashMap<K,V> map,
5614 +             BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5615 +            if (reducer == null) throw new NullPointerException();
5616 +            return new ReduceEntriesTask<K,V>
5617 +                (map, null, -1, null, reducer);
5618 +        }
5619 +
5620 +        /**
5621 +         * Returns a task that when invoked, returns the result of
5622 +         * accumulating the given transformation of all entries using the
5623 +         * given reducer to combine values, or null if none.
5624 +         *
5625 +         * @param map the map
5626 +         * @param transformer a function returning the transformation
5627 +         * for an element, or null if there is no transformation (in
5628 +         * which case it is not combined)
5629 +         * @param reducer a commutative associative combining function
5630 +         * @return the task
5631 +         */
5632 +        public static <K,V,U> ForkJoinTask<U> reduceEntries
5633 +            (ConcurrentHashMap<K,V> map,
5634 +             Function<Map.Entry<K,V>, ? extends U> transformer,
5635 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
5636 +            if (transformer == null || reducer == null)
5637 +                throw new NullPointerException();
5638 +            return new MapReduceEntriesTask<K,V,U>
5639 +                (map, null, -1, null, transformer, reducer);
5640 +        }
5641 +
5642 +        /**
5643 +         * Returns a task that when invoked, returns the result of
5644 +         * accumulating the given transformation of all entries using the
5645 +         * given reducer to combine values, and the given basis as an
5646 +         * identity value.
5647 +         *
5648 +         * @param map the map
5649 +         * @param transformer a function returning the transformation
5650 +         * for an element
5651 +         * @param basis the identity (initial default value) for the reduction
5652 +         * @param reducer a commutative associative combining function
5653 +         * @return the task
5654 +         */
5655 +        public static <K,V> ForkJoinTask<Double> reduceEntriesToDouble
5656 +            (ConcurrentHashMap<K,V> map,
5657 +             ToDoubleFunction<Map.Entry<K,V>> transformer,
5658 +             double basis,
5659 +             DoubleBinaryOperator reducer) {
5660 +            if (transformer == null || reducer == null)
5661 +                throw new NullPointerException();
5662 +            return new MapReduceEntriesToDoubleTask<K,V>
5663 +                (map, null, -1, null, transformer, basis, reducer);
5664 +        }
5665 +
5666 +        /**
5667 +         * Returns a task that when invoked, returns the result of
5668 +         * accumulating the given transformation of all entries using the
5669 +         * given reducer to combine values, and the given basis as an
5670 +         * identity value.
5671 +         *
5672 +         * @param map the map
5673 +         * @param transformer a function returning the transformation
5674 +         * for an element
5675 +         * @param basis the identity (initial default value) for the reduction
5676 +         * @param reducer a commutative associative combining function
5677 +         * @return the task
5678 +         */
5679 +        public static <K,V> ForkJoinTask<Long> reduceEntriesToLong
5680 +            (ConcurrentHashMap<K,V> map,
5681 +             ToLongFunction<Map.Entry<K,V>> transformer,
5682 +             long basis,
5683 +             LongBinaryOperator reducer) {
5684 +            if (transformer == null || reducer == null)
5685 +                throw new NullPointerException();
5686 +            return new MapReduceEntriesToLongTask<K,V>
5687 +                (map, null, -1, null, transformer, basis, reducer);
5688 +        }
5689 +
5690 +        /**
5691 +         * Returns a task that when invoked, returns the result of
5692 +         * accumulating the given transformation of all entries using the
5693 +         * given reducer to combine values, and the given basis as an
5694 +         * identity value.
5695 +         *
5696 +         * @param map the map
5697 +         * @param transformer a function returning the transformation
5698 +         * for an element
5699 +         * @param basis the identity (initial default value) for the reduction
5700 +         * @param reducer a commutative associative combining function
5701 +         * @return the task
5702 +         */
5703 +        public static <K,V> ForkJoinTask<Integer> reduceEntriesToInt
5704 +            (ConcurrentHashMap<K,V> map,
5705 +             ToIntFunction<Map.Entry<K,V>> transformer,
5706 +             int basis,
5707 +             IntBinaryOperator reducer) {
5708 +            if (transformer == null || reducer == null)
5709 +                throw new NullPointerException();
5710 +            return new MapReduceEntriesToIntTask<K,V>
5711 +                (map, null, -1, null, transformer, basis, reducer);
5712 +        }
5713 +    }
5714 +
5715 +    // -------------------------------------------------------
5716 +
5717 +    /*
5718 +     * Task classes. Coded in a regular but ugly format/style to
5719 +     * simplify checks that each variant differs in the right way from
5720 +     * others. The null screenings exist because compilers cannot tell
5721 +     * that we've already null-checked task arguments, so we force
5722 +     * simplest hoisted bypass to help avoid convoluted traps.
5723 +     */
5724 +
5725 +    @SuppressWarnings("serial") static final class ForEachKeyTask<K,V>
5726 +        extends Traverser<K,V,Void> {
5727 +        final Consumer<? super K> action;
5728 +        ForEachKeyTask
5729 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5730 +             Consumer<? super K> action) {
5731 +            super(m, p, b);
5732 +            this.action = action;
5733 +        }
5734 +        public final void compute() {
5735 +            final Consumer<? super K> action;
5736 +            if ((action = this.action) != null) {
5737 +                for (int b; (b = preSplit()) > 0;)
5738 +                    new ForEachKeyTask<K,V>(map, this, b, action).fork();
5739 +                forEachKey(action);
5740 +                propagateCompletion();
5741 +            }
5742 +        }
5743 +    }
5744 +
5745 +    @SuppressWarnings("serial") static final class ForEachValueTask<K,V>
5746 +        extends Traverser<K,V,Void> {
5747 +        final Consumer<? super V> action;
5748 +        ForEachValueTask
5749 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5750 +             Consumer<? super V> action) {
5751 +            super(m, p, b);
5752 +            this.action = action;
5753 +        }
5754 +        public final void compute() {
5755 +            final Consumer<? super V> action;
5756 +            if ((action = this.action) != null) {
5757 +                for (int b; (b = preSplit()) > 0;)
5758 +                    new ForEachValueTask<K,V>(map, this, b, action).fork();
5759 +                forEachValue(action);
5760 +                propagateCompletion();
5761 +            }
5762 +        }
5763 +    }
5764 +
5765 +    @SuppressWarnings("serial") static final class ForEachEntryTask<K,V>
5766 +        extends Traverser<K,V,Void> {
5767 +        final Consumer<? super Entry<K,V>> action;
5768 +        ForEachEntryTask
5769 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5770 +             Consumer<? super Entry<K,V>> action) {
5771 +            super(m, p, b);
5772 +            this.action = action;
5773 +        }
5774 +        public final void compute() {
5775 +            final Consumer<? super Entry<K,V>> action;
5776 +            if ((action = this.action) != null) {
5777 +                for (int b; (b = preSplit()) > 0;)
5778 +                    new ForEachEntryTask<K,V>(map, this, b, action).fork();
5779 +                V v;
5780 +                while ((v = advanceValue()) != null)
5781 +                    action.accept(entryFor(nextKey, v));
5782 +                propagateCompletion();
5783 +            }
5784 +        }
5785 +    }
5786 +
5787 +    @SuppressWarnings("serial") static final class ForEachMappingTask<K,V>
5788 +        extends Traverser<K,V,Void> {
5789 +        final BiConsumer<? super K, ? super V> action;
5790 +        ForEachMappingTask
5791 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5792 +             BiConsumer<? super K,? super V> action) {
5793 +            super(m, p, b);
5794 +            this.action = action;
5795 +        }
5796 +        public final void compute() {
5797 +            final BiConsumer<? super K, ? super V> action;
5798 +            if ((action = this.action) != null) {
5799 +                for (int b; (b = preSplit()) > 0;)
5800 +                    new ForEachMappingTask<K,V>(map, this, b, action).fork();
5801 +                V v;
5802 +                while ((v = advanceValue()) != null)
5803 +                    action.accept(nextKey, v);
5804 +                propagateCompletion();
5805 +            }
5806 +        }
5807 +    }
5808 +
5809 +    @SuppressWarnings("serial") static final class ForEachTransformedKeyTask<K,V,U>
5810 +        extends Traverser<K,V,Void> {
5811 +        final Function<? super K, ? extends U> transformer;
5812 +        final Consumer<? super U> action;
5813 +        ForEachTransformedKeyTask
5814 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5815 +             Function<? super K, ? extends U> transformer, Consumer<? super U> action) {
5816 +            super(m, p, b);
5817 +            this.transformer = transformer; this.action = action;
5818 +        }
5819 +        public final void compute() {
5820 +            final Function<? super K, ? extends U> transformer;
5821 +            final Consumer<? super U> action;
5822 +            if ((transformer = this.transformer) != null &&
5823 +                (action = this.action) != null) {
5824 +                for (int b; (b = preSplit()) > 0;)
5825 +                    new ForEachTransformedKeyTask<K,V,U>
5826 +                        (map, this, b, transformer, action).fork();
5827 +                K k; U u;
5828 +                while ((k = advanceKey()) != null) {
5829 +                    if ((u = transformer.apply(k)) != null)
5830 +                        action.accept(u);
5831 +                }
5832 +                propagateCompletion();
5833 +            }
5834 +        }
5835 +    }
5836 +
5837 +    @SuppressWarnings("serial") static final class ForEachTransformedValueTask<K,V,U>
5838 +        extends Traverser<K,V,Void> {
5839 +        final Function<? super V, ? extends U> transformer;
5840 +        final Consumer<? super U> action;
5841 +        ForEachTransformedValueTask
5842 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5843 +             Function<? super V, ? extends U> transformer, Consumer<? super U> action) {
5844 +            super(m, p, b);
5845 +            this.transformer = transformer; this.action = action;
5846 +        }
5847 +        public final void compute() {
5848 +            final Function<? super V, ? extends U> transformer;
5849 +            final Consumer<? super U> action;
5850 +            if ((transformer = this.transformer) != null &&
5851 +                (action = this.action) != null) {
5852 +                for (int b; (b = preSplit()) > 0;)
5853 +                    new ForEachTransformedValueTask<K,V,U>
5854 +                        (map, this, b, transformer, action).fork();
5855 +                V v; U u;
5856 +                while ((v = advanceValue()) != null) {
5857 +                    if ((u = transformer.apply(v)) != null)
5858 +                        action.accept(u);
5859 +                }
5860 +                propagateCompletion();
5861 +            }
5862 +        }
5863 +    }
5864 +
5865 +    @SuppressWarnings("serial") static final class ForEachTransformedEntryTask<K,V,U>
5866 +        extends Traverser<K,V,Void> {
5867 +        final Function<Map.Entry<K,V>, ? extends U> transformer;
5868 +        final Consumer<? super U> action;
5869 +        ForEachTransformedEntryTask
5870 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5871 +             Function<Map.Entry<K,V>, ? extends U> transformer, Consumer<? super U> action) {
5872 +            super(m, p, b);
5873 +            this.transformer = transformer; this.action = action;
5874 +        }
5875 +        public final void compute() {
5876 +            final Function<Map.Entry<K,V>, ? extends U> transformer;
5877 +            final Consumer<? super U> action;
5878 +            if ((transformer = this.transformer) != null &&
5879 +                (action = this.action) != null) {
5880 +                for (int b; (b = preSplit()) > 0;)
5881 +                    new ForEachTransformedEntryTask<K,V,U>
5882 +                        (map, this, b, transformer, action).fork();
5883 +                V v; U u;
5884 +                while ((v = advanceValue()) != null) {
5885 +                    if ((u = transformer.apply(entryFor(nextKey,
5886 +                                                        v))) != null)
5887 +                        action.accept(u);
5888 +                }
5889 +                propagateCompletion();
5890 +            }
5891 +        }
5892 +    }
5893 +
5894 +    @SuppressWarnings("serial") static final class ForEachTransformedMappingTask<K,V,U>
5895 +        extends Traverser<K,V,Void> {
5896 +        final BiFunction<? super K, ? super V, ? extends U> transformer;
5897 +        final Consumer<? super U> action;
5898 +        ForEachTransformedMappingTask
5899 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5900 +             BiFunction<? super K, ? super V, ? extends U> transformer,
5901 +             Consumer<? super U> action) {
5902 +            super(m, p, b);
5903 +            this.transformer = transformer; this.action = action;
5904 +        }
5905 +        public final void compute() {
5906 +            final BiFunction<? super K, ? super V, ? extends U> transformer;
5907 +            final Consumer<? super U> action;
5908 +            if ((transformer = this.transformer) != null &&
5909 +                (action = this.action) != null) {
5910 +                for (int b; (b = preSplit()) > 0;)
5911 +                    new ForEachTransformedMappingTask<K,V,U>
5912 +                        (map, this, b, transformer, action).fork();
5913 +                V v; U u;
5914 +                while ((v = advanceValue()) != null) {
5915 +                    if ((u = transformer.apply(nextKey, v)) != null)
5916 +                        action.accept(u);
5917 +                }
5918 +                propagateCompletion();
5919 +            }
5920 +        }
5921 +    }
5922 +
5923 +    @SuppressWarnings("serial") static final class SearchKeysTask<K,V,U>
5924 +        extends Traverser<K,V,U> {
5925 +        final Function<? super K, ? extends U> searchFunction;
5926 +        final AtomicReference<U> result;
5927 +        SearchKeysTask
5928 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5929 +             Function<? super K, ? extends U> searchFunction,
5930 +             AtomicReference<U> result) {
5931 +            super(m, p, b);
5932 +            this.searchFunction = searchFunction; this.result = result;
5933 +        }
5934 +        public final U getRawResult() { return result.get(); }
5935 +        public final void compute() {
5936 +            final Function<? super K, ? extends U> searchFunction;
5937 +            final AtomicReference<U> result;
5938 +            if ((searchFunction = this.searchFunction) != null &&
5939 +                (result = this.result) != null) {
5940 +                for (int b;;) {
5941 +                    if (result.get() != null)
5942 +                        return;
5943 +                    if ((b = preSplit()) <= 0)
5944 +                        break;
5945 +                    new SearchKeysTask<K,V,U>
5946 +                        (map, this, b, searchFunction, result).fork();
5947 +                }
5948 +                while (result.get() == null) {
5949 +                    K k; U u;
5950 +                    if ((k = advanceKey()) == null) {
5951 +                        propagateCompletion();
5952 +                        break;
5953 +                    }
5954 +                    if ((u = searchFunction.apply(k)) != null) {
5955 +                        if (result.compareAndSet(null, u))
5956 +                            quietlyCompleteRoot();
5957 +                        break;
5958 +                    }
5959 +                }
5960 +            }
5961 +        }
5962 +    }
5963 +
5964 +    @SuppressWarnings("serial") static final class SearchValuesTask<K,V,U>
5965 +        extends Traverser<K,V,U> {
5966 +        final Function<? super V, ? extends U> searchFunction;
5967 +        final AtomicReference<U> result;
5968 +        SearchValuesTask
5969 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
5970 +             Function<? super V, ? extends U> searchFunction,
5971 +             AtomicReference<U> result) {
5972 +            super(m, p, b);
5973 +            this.searchFunction = searchFunction; this.result = result;
5974 +        }
5975 +        public final U getRawResult() { return result.get(); }
5976 +        public final void compute() {
5977 +            final Function<? super V, ? extends U> searchFunction;
5978 +            final AtomicReference<U> result;
5979 +            if ((searchFunction = this.searchFunction) != null &&
5980 +                (result = this.result) != null) {
5981 +                for (int b;;) {
5982 +                    if (result.get() != null)
5983 +                        return;
5984 +                    if ((b = preSplit()) <= 0)
5985 +                        break;
5986 +                    new SearchValuesTask<K,V,U>
5987 +                        (map, this, b, searchFunction, result).fork();
5988 +                }
5989 +                while (result.get() == null) {
5990 +                    V v; U u;
5991 +                    if ((v = advanceValue()) == null) {
5992 +                        propagateCompletion();
5993 +                        break;
5994 +                    }
5995 +                    if ((u = searchFunction.apply(v)) != null) {
5996 +                        if (result.compareAndSet(null, u))
5997 +                            quietlyCompleteRoot();
5998 +                        break;
5999 +                    }
6000 +                }
6001 +            }
6002 +        }
6003 +    }
6004 +
6005 +    @SuppressWarnings("serial") static final class SearchEntriesTask<K,V,U>
6006 +        extends Traverser<K,V,U> {
6007 +        final Function<Entry<K,V>, ? extends U> searchFunction;
6008 +        final AtomicReference<U> result;
6009 +        SearchEntriesTask
6010 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6011 +             Function<Entry<K,V>, ? extends U> searchFunction,
6012 +             AtomicReference<U> result) {
6013 +            super(m, p, b);
6014 +            this.searchFunction = searchFunction; this.result = result;
6015 +        }
6016 +        public final U getRawResult() { return result.get(); }
6017 +        public final void compute() {
6018 +            final Function<Entry<K,V>, ? extends U> searchFunction;
6019 +            final AtomicReference<U> result;
6020 +            if ((searchFunction = this.searchFunction) != null &&
6021 +                (result = this.result) != null) {
6022 +                for (int b;;) {
6023 +                    if (result.get() != null)
6024 +                        return;
6025 +                    if ((b = preSplit()) <= 0)
6026 +                        break;
6027 +                    new SearchEntriesTask<K,V,U>
6028 +                        (map, this, b, searchFunction, result).fork();
6029 +                }
6030 +                while (result.get() == null) {
6031 +                    V v; U u;
6032 +                    if ((v = advanceValue()) == null) {
6033 +                        propagateCompletion();
6034 +                        break;
6035 +                    }
6036 +                    if ((u = searchFunction.apply(entryFor(nextKey,
6037 +                                                           v))) != null) {
6038 +                        if (result.compareAndSet(null, u))
6039 +                            quietlyCompleteRoot();
6040 +                        return;
6041 +                    }
6042 +                }
6043 +            }
6044 +        }
6045 +    }
6046 +
6047 +    @SuppressWarnings("serial") static final class SearchMappingsTask<K,V,U>
6048 +        extends Traverser<K,V,U> {
6049 +        final BiFunction<? super K, ? super V, ? extends U> searchFunction;
6050 +        final AtomicReference<U> result;
6051 +        SearchMappingsTask
6052 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6053 +             BiFunction<? super K, ? super V, ? extends U> searchFunction,
6054 +             AtomicReference<U> result) {
6055 +            super(m, p, b);
6056 +            this.searchFunction = searchFunction; this.result = result;
6057 +        }
6058 +        public final U getRawResult() { return result.get(); }
6059 +        public final void compute() {
6060 +            final BiFunction<? super K, ? super V, ? extends U> searchFunction;
6061 +            final AtomicReference<U> result;
6062 +            if ((searchFunction = this.searchFunction) != null &&
6063 +                (result = this.result) != null) {
6064 +                for (int b;;) {
6065 +                    if (result.get() != null)
6066 +                        return;
6067 +                    if ((b = preSplit()) <= 0)
6068 +                        break;
6069 +                    new SearchMappingsTask<K,V,U>
6070 +                        (map, this, b, searchFunction, result).fork();
6071 +                }
6072 +                while (result.get() == null) {
6073 +                    V v; U u;
6074 +                    if ((v = advanceValue()) == null) {
6075 +                        propagateCompletion();
6076 +                        break;
6077 +                    }
6078 +                    if ((u = searchFunction.apply(nextKey, v)) != null) {
6079 +                        if (result.compareAndSet(null, u))
6080 +                            quietlyCompleteRoot();
6081 +                        break;
6082 +                    }
6083 +                }
6084 +            }
6085 +        }
6086 +    }
6087 +
6088 +    @SuppressWarnings("serial") static final class ReduceKeysTask<K,V>
6089 +        extends Traverser<K,V,K> {
6090 +        final BiFunction<? super K, ? super K, ? extends K> reducer;
6091 +        K result;
6092 +        ReduceKeysTask<K,V> rights, nextRight;
6093 +        ReduceKeysTask
6094 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6095 +             ReduceKeysTask<K,V> nextRight,
6096 +             BiFunction<? super K, ? super K, ? extends K> reducer) {
6097 +            super(m, p, b); this.nextRight = nextRight;
6098 +            this.reducer = reducer;
6099 +        }
6100 +        public final K getRawResult() { return result; }
6101 +        @SuppressWarnings("unchecked") public final void compute() {
6102 +            final BiFunction<? super K, ? super K, ? extends K> reducer;
6103 +            if ((reducer = this.reducer) != null) {
6104 +                for (int b; (b = preSplit()) > 0;)
6105 +                    (rights = new ReduceKeysTask<K,V>
6106 +                     (map, this, b, rights, reducer)).fork();
6107 +                K u, r = null;
6108 +                while ((u = advanceKey()) != null) {
6109 +                    r = (r == null) ? u : u == null ? r : reducer.apply(r, u);
6110 +                }
6111 +                result = r;
6112 +                CountedCompleter<?> c;
6113 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6114 +                    ReduceKeysTask<K,V>
6115 +                        t = (ReduceKeysTask<K,V>)c,
6116 +                        s = t.rights;
6117 +                    while (s != null) {
6118 +                        K tr, sr;
6119 +                        if ((sr = s.result) != null)
6120 +                            t.result = (((tr = t.result) == null) ? sr :
6121 +                                        reducer.apply(tr, sr));
6122 +                        s = t.rights = s.nextRight;
6123 +                    }
6124 +                }
6125 +            }
6126 +        }
6127 +    }
6128 +
6129 +    @SuppressWarnings("serial") static final class ReduceValuesTask<K,V>
6130 +        extends Traverser<K,V,V> {
6131 +        final BiFunction<? super V, ? super V, ? extends V> reducer;
6132 +        V result;
6133 +        ReduceValuesTask<K,V> rights, nextRight;
6134 +        ReduceValuesTask
6135 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6136 +             ReduceValuesTask<K,V> nextRight,
6137 +             BiFunction<? super V, ? super V, ? extends V> reducer) {
6138 +            super(m, p, b); this.nextRight = nextRight;
6139 +            this.reducer = reducer;
6140 +        }
6141 +        public final V getRawResult() { return result; }
6142 +        @SuppressWarnings("unchecked") public final void compute() {
6143 +            final BiFunction<? super V, ? super V, ? extends V> reducer;
6144 +            if ((reducer = this.reducer) != null) {
6145 +                for (int b; (b = preSplit()) > 0;)
6146 +                    (rights = new ReduceValuesTask<K,V>
6147 +                     (map, this, b, rights, reducer)).fork();
6148 +                V r = null, v;
6149 +                while ((v = advanceValue()) != null)
6150 +                    r = (r == null) ? v : reducer.apply(r, v);
6151 +                result = r;
6152 +                CountedCompleter<?> c;
6153 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6154 +                    ReduceValuesTask<K,V>
6155 +                        t = (ReduceValuesTask<K,V>)c,
6156 +                        s = t.rights;
6157 +                    while (s != null) {
6158 +                        V tr, sr;
6159 +                        if ((sr = s.result) != null)
6160 +                            t.result = (((tr = t.result) == null) ? sr :
6161 +                                        reducer.apply(tr, sr));
6162 +                        s = t.rights = s.nextRight;
6163 +                    }
6164 +                }
6165 +            }
6166 +        }
6167 +    }
6168 +
6169 +    @SuppressWarnings("serial") static final class ReduceEntriesTask<K,V>
6170 +        extends Traverser<K,V,Map.Entry<K,V>> {
6171 +        final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
6172 +        Map.Entry<K,V> result;
6173 +        ReduceEntriesTask<K,V> rights, nextRight;
6174 +        ReduceEntriesTask
6175 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6176 +             ReduceEntriesTask<K,V> nextRight,
6177 +             BiFunction<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
6178 +            super(m, p, b); this.nextRight = nextRight;
6179 +            this.reducer = reducer;
6180 +        }
6181 +        public final Map.Entry<K,V> getRawResult() { return result; }
6182 +        @SuppressWarnings("unchecked") public final void compute() {
6183 +            final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
6184 +            if ((reducer = this.reducer) != null) {
6185 +                for (int b; (b = preSplit()) > 0;)
6186 +                    (rights = new ReduceEntriesTask<K,V>
6187 +                     (map, this, b, rights, reducer)).fork();
6188 +                Map.Entry<K,V> r = null;
6189 +                V v;
6190 +                while ((v = advanceValue()) != null) {
6191 +                    Map.Entry<K,V> u = entryFor(nextKey, v);
6192 +                    r = (r == null) ? u : reducer.apply(r, u);
6193 +                }
6194 +                result = r;
6195 +                CountedCompleter<?> c;
6196 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6197 +                    ReduceEntriesTask<K,V>
6198 +                        t = (ReduceEntriesTask<K,V>)c,
6199 +                        s = t.rights;
6200 +                    while (s != null) {
6201 +                        Map.Entry<K,V> tr, sr;
6202 +                        if ((sr = s.result) != null)
6203 +                            t.result = (((tr = t.result) == null) ? sr :
6204 +                                        reducer.apply(tr, sr));
6205 +                        s = t.rights = s.nextRight;
6206 +                    }
6207 +                }
6208 +            }
6209 +        }
6210 +    }
6211 +
6212 +    @SuppressWarnings("serial") static final class MapReduceKeysTask<K,V,U>
6213 +        extends Traverser<K,V,U> {
6214 +        final Function<? super K, ? extends U> transformer;
6215 +        final BiFunction<? super U, ? super U, ? extends U> reducer;
6216 +        U result;
6217 +        MapReduceKeysTask<K,V,U> rights, nextRight;
6218 +        MapReduceKeysTask
6219 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6220 +             MapReduceKeysTask<K,V,U> nextRight,
6221 +             Function<? super K, ? extends U> transformer,
6222 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
6223 +            super(m, p, b); this.nextRight = nextRight;
6224 +            this.transformer = transformer;
6225 +            this.reducer = reducer;
6226 +        }
6227 +        public final U getRawResult() { return result; }
6228 +        @SuppressWarnings("unchecked") public final void compute() {
6229 +            final Function<? super K, ? extends U> transformer;
6230 +            final BiFunction<? super U, ? super U, ? extends U> reducer;
6231 +            if ((transformer = this.transformer) != null &&
6232 +                (reducer = this.reducer) != null) {
6233 +                for (int b; (b = preSplit()) > 0;)
6234 +                    (rights = new MapReduceKeysTask<K,V,U>
6235 +                     (map, this, b, rights, transformer, reducer)).fork();
6236 +                K k; U r = null, u;
6237 +                while ((k = advanceKey()) != null) {
6238 +                    if ((u = transformer.apply(k)) != null)
6239 +                        r = (r == null) ? u : reducer.apply(r, u);
6240 +                }
6241 +                result = r;
6242 +                CountedCompleter<?> c;
6243 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6244 +                    MapReduceKeysTask<K,V,U>
6245 +                        t = (MapReduceKeysTask<K,V,U>)c,
6246 +                        s = t.rights;
6247 +                    while (s != null) {
6248 +                        U tr, sr;
6249 +                        if ((sr = s.result) != null)
6250 +                            t.result = (((tr = t.result) == null) ? sr :
6251 +                                        reducer.apply(tr, sr));
6252 +                        s = t.rights = s.nextRight;
6253 +                    }
6254 +                }
6255 +            }
6256 +        }
6257 +    }
6258 +
6259 +    @SuppressWarnings("serial") static final class MapReduceValuesTask<K,V,U>
6260 +        extends Traverser<K,V,U> {
6261 +        final Function<? super V, ? extends U> transformer;
6262 +        final BiFunction<? super U, ? super U, ? extends U> reducer;
6263 +        U result;
6264 +        MapReduceValuesTask<K,V,U> rights, nextRight;
6265 +        MapReduceValuesTask
6266 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6267 +             MapReduceValuesTask<K,V,U> nextRight,
6268 +             Function<? super V, ? extends U> transformer,
6269 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
6270 +            super(m, p, b); this.nextRight = nextRight;
6271 +            this.transformer = transformer;
6272 +            this.reducer = reducer;
6273 +        }
6274 +        public final U getRawResult() { return result; }
6275 +        @SuppressWarnings("unchecked") public final void compute() {
6276 +            final Function<? super V, ? extends U> transformer;
6277 +            final BiFunction<? super U, ? super U, ? extends U> reducer;
6278 +            if ((transformer = this.transformer) != null &&
6279 +                (reducer = this.reducer) != null) {
6280 +                for (int b; (b = preSplit()) > 0;)
6281 +                    (rights = new MapReduceValuesTask<K,V,U>
6282 +                     (map, this, b, rights, transformer, reducer)).fork();
6283 +                U r = null, u;
6284 +                V v;
6285 +                while ((v = advanceValue()) != null) {
6286 +                    if ((u = transformer.apply(v)) != null)
6287 +                        r = (r == null) ? u : reducer.apply(r, u);
6288 +                }
6289 +                result = r;
6290 +                CountedCompleter<?> c;
6291 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6292 +                    MapReduceValuesTask<K,V,U>
6293 +                        t = (MapReduceValuesTask<K,V,U>)c,
6294 +                        s = t.rights;
6295 +                    while (s != null) {
6296 +                        U tr, sr;
6297 +                        if ((sr = s.result) != null)
6298 +                            t.result = (((tr = t.result) == null) ? sr :
6299 +                                        reducer.apply(tr, sr));
6300 +                        s = t.rights = s.nextRight;
6301 +                    }
6302 +                }
6303 +            }
6304 +        }
6305 +    }
6306 +
6307 +    @SuppressWarnings("serial") static final class MapReduceEntriesTask<K,V,U>
6308 +        extends Traverser<K,V,U> {
6309 +        final Function<Map.Entry<K,V>, ? extends U> transformer;
6310 +        final BiFunction<? super U, ? super U, ? extends U> reducer;
6311 +        U result;
6312 +        MapReduceEntriesTask<K,V,U> rights, nextRight;
6313 +        MapReduceEntriesTask
6314 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6315 +             MapReduceEntriesTask<K,V,U> nextRight,
6316 +             Function<Map.Entry<K,V>, ? extends U> transformer,
6317 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
6318 +            super(m, p, b); this.nextRight = nextRight;
6319 +            this.transformer = transformer;
6320 +            this.reducer = reducer;
6321 +        }
6322 +        public final U getRawResult() { return result; }
6323 +        @SuppressWarnings("unchecked") public final void compute() {
6324 +            final Function<Map.Entry<K,V>, ? extends U> transformer;
6325 +            final BiFunction<? super U, ? super U, ? extends U> reducer;
6326 +            if ((transformer = this.transformer) != null &&
6327 +                (reducer = this.reducer) != null) {
6328 +                for (int b; (b = preSplit()) > 0;)
6329 +                    (rights = new MapReduceEntriesTask<K,V,U>
6330 +                     (map, this, b, rights, transformer, reducer)).fork();
6331 +                U r = null, u;
6332 +                V v;
6333 +                while ((v = advanceValue()) != null) {
6334 +                    if ((u = transformer.apply(entryFor(nextKey,
6335 +                                                        v))) != null)
6336 +                        r = (r == null) ? u : reducer.apply(r, u);
6337 +                }
6338 +                result = r;
6339 +                CountedCompleter<?> c;
6340 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6341 +                    MapReduceEntriesTask<K,V,U>
6342 +                        t = (MapReduceEntriesTask<K,V,U>)c,
6343 +                        s = t.rights;
6344 +                    while (s != null) {
6345 +                        U tr, sr;
6346 +                        if ((sr = s.result) != null)
6347 +                            t.result = (((tr = t.result) == null) ? sr :
6348 +                                        reducer.apply(tr, sr));
6349 +                        s = t.rights = s.nextRight;
6350 +                    }
6351 +                }
6352 +            }
6353 +        }
6354 +    }
6355 +
6356 +    @SuppressWarnings("serial") static final class MapReduceMappingsTask<K,V,U>
6357 +        extends Traverser<K,V,U> {
6358 +        final BiFunction<? super K, ? super V, ? extends U> transformer;
6359 +        final BiFunction<? super U, ? super U, ? extends U> reducer;
6360 +        U result;
6361 +        MapReduceMappingsTask<K,V,U> rights, nextRight;
6362 +        MapReduceMappingsTask
6363 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6364 +             MapReduceMappingsTask<K,V,U> nextRight,
6365 +             BiFunction<? super K, ? super V, ? extends U> transformer,
6366 +             BiFunction<? super U, ? super U, ? extends U> reducer) {
6367 +            super(m, p, b); this.nextRight = nextRight;
6368 +            this.transformer = transformer;
6369 +            this.reducer = reducer;
6370 +        }
6371 +        public final U getRawResult() { return result; }
6372 +        @SuppressWarnings("unchecked") public final void compute() {
6373 +            final BiFunction<? super K, ? super V, ? extends U> transformer;
6374 +            final BiFunction<? super U, ? super U, ? extends U> reducer;
6375 +            if ((transformer = this.transformer) != null &&
6376 +                (reducer = this.reducer) != null) {
6377 +                for (int b; (b = preSplit()) > 0;)
6378 +                    (rights = new MapReduceMappingsTask<K,V,U>
6379 +                     (map, this, b, rights, transformer, reducer)).fork();
6380 +                U r = null, u;
6381 +                V v;
6382 +                while ((v = advanceValue()) != null) {
6383 +                    if ((u = transformer.apply(nextKey, v)) != null)
6384 +                        r = (r == null) ? u : reducer.apply(r, u);
6385 +                }
6386 +                result = r;
6387 +                CountedCompleter<?> c;
6388 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6389 +                    MapReduceMappingsTask<K,V,U>
6390 +                        t = (MapReduceMappingsTask<K,V,U>)c,
6391 +                        s = t.rights;
6392 +                    while (s != null) {
6393 +                        U tr, sr;
6394 +                        if ((sr = s.result) != null)
6395 +                            t.result = (((tr = t.result) == null) ? sr :
6396 +                                        reducer.apply(tr, sr));
6397 +                        s = t.rights = s.nextRight;
6398 +                    }
6399 +                }
6400 +            }
6401 +        }
6402 +    }
6403 +
6404 +    @SuppressWarnings("serial") static final class MapReduceKeysToDoubleTask<K,V>
6405 +        extends Traverser<K,V,Double> {
6406 +        final ToDoubleFunction<? super K> transformer;
6407 +        final DoubleBinaryOperator reducer;
6408 +        final double basis;
6409 +        double result;
6410 +        MapReduceKeysToDoubleTask<K,V> rights, nextRight;
6411 +        MapReduceKeysToDoubleTask
6412 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6413 +             MapReduceKeysToDoubleTask<K,V> nextRight,
6414 +             ToDoubleFunction<? super K> transformer,
6415 +             double basis,
6416 +             DoubleBinaryOperator reducer) {
6417 +            super(m, p, b); this.nextRight = nextRight;
6418 +            this.transformer = transformer;
6419 +            this.basis = basis; this.reducer = reducer;
6420 +        }
6421 +        public final Double getRawResult() { return result; }
6422 +        @SuppressWarnings("unchecked") public final void compute() {
6423 +            final ToDoubleFunction<? super K> transformer;
6424 +            final DoubleBinaryOperator reducer;
6425 +            if ((transformer = this.transformer) != null &&
6426 +                (reducer = this.reducer) != null) {
6427 +                double r = this.basis;
6428 +                for (int b; (b = preSplit()) > 0;)
6429 +                    (rights = new MapReduceKeysToDoubleTask<K,V>
6430 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6431 +                K k;
6432 +                while ((k = advanceKey()) != null)
6433 +                    r = reducer.applyAsDouble(r, transformer.applyAsDouble(k));
6434 +                result = r;
6435 +                CountedCompleter<?> c;
6436 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6437 +                    MapReduceKeysToDoubleTask<K,V>
6438 +                        t = (MapReduceKeysToDoubleTask<K,V>)c,
6439 +                        s = t.rights;
6440 +                    while (s != null) {
6441 +                        t.result = reducer.applyAsDouble(t.result, s.result);
6442 +                        s = t.rights = s.nextRight;
6443 +                    }
6444 +                }
6445 +            }
6446 +        }
6447 +    }
6448 +
6449 +    @SuppressWarnings("serial") static final class MapReduceValuesToDoubleTask<K,V>
6450 +        extends Traverser<K,V,Double> {
6451 +        final ToDoubleFunction<? super V> transformer;
6452 +        final DoubleBinaryOperator reducer;
6453 +        final double basis;
6454 +        double result;
6455 +        MapReduceValuesToDoubleTask<K,V> rights, nextRight;
6456 +        MapReduceValuesToDoubleTask
6457 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6458 +             MapReduceValuesToDoubleTask<K,V> nextRight,
6459 +             ToDoubleFunction<? super V> transformer,
6460 +             double basis,
6461 +             DoubleBinaryOperator reducer) {
6462 +            super(m, p, b); this.nextRight = nextRight;
6463 +            this.transformer = transformer;
6464 +            this.basis = basis; this.reducer = reducer;
6465 +        }
6466 +        public final Double getRawResult() { return result; }
6467 +        @SuppressWarnings("unchecked") public final void compute() {
6468 +            final ToDoubleFunction<? super V> transformer;
6469 +            final DoubleBinaryOperator reducer;
6470 +            if ((transformer = this.transformer) != null &&
6471 +                (reducer = this.reducer) != null) {
6472 +                double r = this.basis;
6473 +                for (int b; (b = preSplit()) > 0;)
6474 +                    (rights = new MapReduceValuesToDoubleTask<K,V>
6475 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6476 +                V v;
6477 +                while ((v = advanceValue()) != null)
6478 +                    r = reducer.applyAsDouble(r, transformer.applyAsDouble(v));
6479 +                result = r;
6480 +                CountedCompleter<?> c;
6481 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6482 +                    MapReduceValuesToDoubleTask<K,V>
6483 +                        t = (MapReduceValuesToDoubleTask<K,V>)c,
6484 +                        s = t.rights;
6485 +                    while (s != null) {
6486 +                        t.result = reducer.applyAsDouble(t.result, s.result);
6487 +                        s = t.rights = s.nextRight;
6488 +                    }
6489 +                }
6490 +            }
6491 +        }
6492 +    }
6493 +
6494 +    @SuppressWarnings("serial") static final class MapReduceEntriesToDoubleTask<K,V>
6495 +        extends Traverser<K,V,Double> {
6496 +        final ToDoubleFunction<Map.Entry<K,V>> transformer;
6497 +        final DoubleBinaryOperator reducer;
6498 +        final double basis;
6499 +        double result;
6500 +        MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
6501 +        MapReduceEntriesToDoubleTask
6502 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6503 +             MapReduceEntriesToDoubleTask<K,V> nextRight,
6504 +             ToDoubleFunction<Map.Entry<K,V>> transformer,
6505 +             double basis,
6506 +             DoubleBinaryOperator reducer) {
6507 +            super(m, p, b); this.nextRight = nextRight;
6508 +            this.transformer = transformer;
6509 +            this.basis = basis; this.reducer = reducer;
6510 +        }
6511 +        public final Double getRawResult() { return result; }
6512 +        @SuppressWarnings("unchecked") public final void compute() {
6513 +            final ToDoubleFunction<Map.Entry<K,V>> transformer;
6514 +            final DoubleBinaryOperator reducer;
6515 +            if ((transformer = this.transformer) != null &&
6516 +                (reducer = this.reducer) != null) {
6517 +                double r = this.basis;
6518 +                for (int b; (b = preSplit()) > 0;)
6519 +                    (rights = new MapReduceEntriesToDoubleTask<K,V>
6520 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6521 +                V v;
6522 +                while ((v = advanceValue()) != null)
6523 +                    r = reducer.applyAsDouble(r, transformer.applyAsDouble(entryFor(nextKey,
6524 +                                                                    v)));
6525 +                result = r;
6526 +                CountedCompleter<?> c;
6527 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6528 +                    MapReduceEntriesToDoubleTask<K,V>
6529 +                        t = (MapReduceEntriesToDoubleTask<K,V>)c,
6530 +                        s = t.rights;
6531 +                    while (s != null) {
6532 +                        t.result = reducer.applyAsDouble(t.result, s.result);
6533 +                        s = t.rights = s.nextRight;
6534 +                    }
6535 +                }
6536 +            }
6537 +        }
6538 +    }
6539 +
6540 +    @SuppressWarnings("serial") static final class MapReduceMappingsToDoubleTask<K,V>
6541 +        extends Traverser<K,V,Double> {
6542 +        final ToDoubleBiFunction<? super K, ? super V> transformer;
6543 +        final DoubleBinaryOperator reducer;
6544 +        final double basis;
6545 +        double result;
6546 +        MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
6547 +        MapReduceMappingsToDoubleTask
6548 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6549 +             MapReduceMappingsToDoubleTask<K,V> nextRight,
6550 +             ToDoubleBiFunction<? super K, ? super V> transformer,
6551 +             double basis,
6552 +             DoubleBinaryOperator reducer) {
6553 +            super(m, p, b); this.nextRight = nextRight;
6554 +            this.transformer = transformer;
6555 +            this.basis = basis; this.reducer = reducer;
6556 +        }
6557 +        public final Double getRawResult() { return result; }
6558 +        @SuppressWarnings("unchecked") public final void compute() {
6559 +            final ToDoubleBiFunction<? super K, ? super V> transformer;
6560 +            final DoubleBinaryOperator reducer;
6561 +            if ((transformer = this.transformer) != null &&
6562 +                (reducer = this.reducer) != null) {
6563 +                double r = this.basis;
6564 +                for (int b; (b = preSplit()) > 0;)
6565 +                    (rights = new MapReduceMappingsToDoubleTask<K,V>
6566 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6567 +                V v;
6568 +                while ((v = advanceValue()) != null)
6569 +                    r = reducer.applyAsDouble(r, transformer.applyAsDouble(nextKey, v));
6570 +                result = r;
6571 +                CountedCompleter<?> c;
6572 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6573 +                    MapReduceMappingsToDoubleTask<K,V>
6574 +                        t = (MapReduceMappingsToDoubleTask<K,V>)c,
6575 +                        s = t.rights;
6576 +                    while (s != null) {
6577 +                        t.result = reducer.applyAsDouble(t.result, s.result);
6578 +                        s = t.rights = s.nextRight;
6579 +                    }
6580 +                }
6581 +            }
6582 +        }
6583 +    }
6584 +
6585 +    @SuppressWarnings("serial") static final class MapReduceKeysToLongTask<K,V>
6586 +        extends Traverser<K,V,Long> {
6587 +        final ToLongFunction<? super K> transformer;
6588 +        final LongBinaryOperator reducer;
6589 +        final long basis;
6590 +        long result;
6591 +        MapReduceKeysToLongTask<K,V> rights, nextRight;
6592 +        MapReduceKeysToLongTask
6593 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6594 +             MapReduceKeysToLongTask<K,V> nextRight,
6595 +             ToLongFunction<? super K> transformer,
6596 +             long basis,
6597 +             LongBinaryOperator reducer) {
6598 +            super(m, p, b); this.nextRight = nextRight;
6599 +            this.transformer = transformer;
6600 +            this.basis = basis; this.reducer = reducer;
6601 +        }
6602 +        public final Long getRawResult() { return result; }
6603 +        @SuppressWarnings("unchecked") public final void compute() {
6604 +            final ToLongFunction<? super K> transformer;
6605 +            final LongBinaryOperator reducer;
6606 +            if ((transformer = this.transformer) != null &&
6607 +                (reducer = this.reducer) != null) {
6608 +                long r = this.basis;
6609 +                for (int b; (b = preSplit()) > 0;)
6610 +                    (rights = new MapReduceKeysToLongTask<K,V>
6611 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6612 +                K k;
6613 +                while ((k = advanceKey()) != null)
6614 +                    r = reducer.applyAsLong(r, transformer.applyAsLong(k));
6615 +                result = r;
6616 +                CountedCompleter<?> c;
6617 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6618 +                    MapReduceKeysToLongTask<K,V>
6619 +                        t = (MapReduceKeysToLongTask<K,V>)c,
6620 +                        s = t.rights;
6621 +                    while (s != null) {
6622 +                        t.result = reducer.applyAsLong(t.result, s.result);
6623 +                        s = t.rights = s.nextRight;
6624 +                    }
6625 +                }
6626 +            }
6627 +        }
6628 +    }
6629 +
6630 +    @SuppressWarnings("serial") static final class MapReduceValuesToLongTask<K,V>
6631 +        extends Traverser<K,V,Long> {
6632 +        final ToLongFunction<? super V> transformer;
6633 +        final LongBinaryOperator reducer;
6634 +        final long basis;
6635 +        long result;
6636 +        MapReduceValuesToLongTask<K,V> rights, nextRight;
6637 +        MapReduceValuesToLongTask
6638 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6639 +             MapReduceValuesToLongTask<K,V> nextRight,
6640 +             ToLongFunction<? super V> transformer,
6641 +             long basis,
6642 +             LongBinaryOperator reducer) {
6643 +            super(m, p, b); this.nextRight = nextRight;
6644 +            this.transformer = transformer;
6645 +            this.basis = basis; this.reducer = reducer;
6646 +        }
6647 +        public final Long getRawResult() { return result; }
6648 +        @SuppressWarnings("unchecked") public final void compute() {
6649 +            final ToLongFunction<? super V> transformer;
6650 +            final LongBinaryOperator reducer;
6651 +            if ((transformer = this.transformer) != null &&
6652 +                (reducer = this.reducer) != null) {
6653 +                long r = this.basis;
6654 +                for (int b; (b = preSplit()) > 0;)
6655 +                    (rights = new MapReduceValuesToLongTask<K,V>
6656 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6657 +                V v;
6658 +                while ((v = advanceValue()) != null)
6659 +                    r = reducer.applyAsLong(r, transformer.applyAsLong(v));
6660 +                result = r;
6661 +                CountedCompleter<?> c;
6662 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6663 +                    MapReduceValuesToLongTask<K,V>
6664 +                        t = (MapReduceValuesToLongTask<K,V>)c,
6665 +                        s = t.rights;
6666 +                    while (s != null) {
6667 +                        t.result = reducer.applyAsLong(t.result, s.result);
6668 +                        s = t.rights = s.nextRight;
6669 +                    }
6670 +                }
6671 +            }
6672 +        }
6673 +    }
6674 +
6675 +    @SuppressWarnings("serial") static final class MapReduceEntriesToLongTask<K,V>
6676 +        extends Traverser<K,V,Long> {
6677 +        final ToLongFunction<Map.Entry<K,V>> transformer;
6678 +        final LongBinaryOperator reducer;
6679 +        final long basis;
6680 +        long result;
6681 +        MapReduceEntriesToLongTask<K,V> rights, nextRight;
6682 +        MapReduceEntriesToLongTask
6683 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6684 +             MapReduceEntriesToLongTask<K,V> nextRight,
6685 +             ToLongFunction<Map.Entry<K,V>> transformer,
6686 +             long basis,
6687 +             LongBinaryOperator reducer) {
6688 +            super(m, p, b); this.nextRight = nextRight;
6689 +            this.transformer = transformer;
6690 +            this.basis = basis; this.reducer = reducer;
6691 +        }
6692 +        public final Long getRawResult() { return result; }
6693 +        @SuppressWarnings("unchecked") public final void compute() {
6694 +            final ToLongFunction<Map.Entry<K,V>> transformer;
6695 +            final LongBinaryOperator reducer;
6696 +            if ((transformer = this.transformer) != null &&
6697 +                (reducer = this.reducer) != null) {
6698 +                long r = this.basis;
6699 +                for (int b; (b = preSplit()) > 0;)
6700 +                    (rights = new MapReduceEntriesToLongTask<K,V>
6701 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6702 +                V v;
6703 +                while ((v = advanceValue()) != null)
6704 +                    r = reducer.applyAsLong(r, transformer.applyAsLong(entryFor(nextKey, v)));
6705 +                result = r;
6706 +                CountedCompleter<?> c;
6707 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6708 +                    MapReduceEntriesToLongTask<K,V>
6709 +                        t = (MapReduceEntriesToLongTask<K,V>)c,
6710 +                        s = t.rights;
6711 +                    while (s != null) {
6712 +                        t.result = reducer.applyAsLong(t.result, s.result);
6713 +                        s = t.rights = s.nextRight;
6714 +                    }
6715 +                }
6716 +            }
6717 +        }
6718 +    }
6719 +
6720 +    @SuppressWarnings("serial") static final class MapReduceMappingsToLongTask<K,V>
6721 +        extends Traverser<K,V,Long> {
6722 +        final ToLongBiFunction<? super K, ? super V> transformer;
6723 +        final LongBinaryOperator reducer;
6724 +        final long basis;
6725 +        long result;
6726 +        MapReduceMappingsToLongTask<K,V> rights, nextRight;
6727 +        MapReduceMappingsToLongTask
6728 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6729 +             MapReduceMappingsToLongTask<K,V> nextRight,
6730 +             ToLongBiFunction<? super K, ? super V> transformer,
6731 +             long basis,
6732 +             LongBinaryOperator reducer) {
6733 +            super(m, p, b); this.nextRight = nextRight;
6734 +            this.transformer = transformer;
6735 +            this.basis = basis; this.reducer = reducer;
6736 +        }
6737 +        public final Long getRawResult() { return result; }
6738 +        @SuppressWarnings("unchecked") public final void compute() {
6739 +            final ToLongBiFunction<? super K, ? super V> transformer;
6740 +            final LongBinaryOperator reducer;
6741 +            if ((transformer = this.transformer) != null &&
6742 +                (reducer = this.reducer) != null) {
6743 +                long r = this.basis;
6744 +                for (int b; (b = preSplit()) > 0;)
6745 +                    (rights = new MapReduceMappingsToLongTask<K,V>
6746 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6747 +                V v;
6748 +                while ((v = advanceValue()) != null)
6749 +                    r = reducer.applyAsLong(r, transformer.applyAsLong(nextKey, v));
6750 +                result = r;
6751 +                CountedCompleter<?> c;
6752 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6753 +                    MapReduceMappingsToLongTask<K,V>
6754 +                        t = (MapReduceMappingsToLongTask<K,V>)c,
6755 +                        s = t.rights;
6756 +                    while (s != null) {
6757 +                        t.result = reducer.applyAsLong(t.result, s.result);
6758 +                        s = t.rights = s.nextRight;
6759 +                    }
6760 +                }
6761 +            }
6762 +        }
6763 +    }
6764 +
6765 +    @SuppressWarnings("serial") static final class MapReduceKeysToIntTask<K,V>
6766 +        extends Traverser<K,V,Integer> {
6767 +        final ToIntFunction<? super K> transformer;
6768 +        final IntBinaryOperator reducer;
6769 +        final int basis;
6770 +        int result;
6771 +        MapReduceKeysToIntTask<K,V> rights, nextRight;
6772 +        MapReduceKeysToIntTask
6773 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6774 +             MapReduceKeysToIntTask<K,V> nextRight,
6775 +             ToIntFunction<? super K> transformer,
6776 +             int basis,
6777 +             IntBinaryOperator reducer) {
6778 +            super(m, p, b); this.nextRight = nextRight;
6779 +            this.transformer = transformer;
6780 +            this.basis = basis; this.reducer = reducer;
6781 +        }
6782 +        public final Integer getRawResult() { return result; }
6783 +        @SuppressWarnings("unchecked") public final void compute() {
6784 +            final ToIntFunction<? super K> transformer;
6785 +            final IntBinaryOperator reducer;
6786 +            if ((transformer = this.transformer) != null &&
6787 +                (reducer = this.reducer) != null) {
6788 +                int r = this.basis;
6789 +                for (int b; (b = preSplit()) > 0;)
6790 +                    (rights = new MapReduceKeysToIntTask<K,V>
6791 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6792 +                K k;
6793 +                while ((k = advanceKey()) != null)
6794 +                    r = reducer.applyAsInt(r, transformer.applyAsInt(k));
6795 +                result = r;
6796 +                CountedCompleter<?> c;
6797 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6798 +                    MapReduceKeysToIntTask<K,V>
6799 +                        t = (MapReduceKeysToIntTask<K,V>)c,
6800 +                        s = t.rights;
6801 +                    while (s != null) {
6802 +                        t.result = reducer.applyAsInt(t.result, s.result);
6803 +                        s = t.rights = s.nextRight;
6804 +                    }
6805 +                }
6806 +            }
6807 +        }
6808 +    }
6809 +
6810 +    @SuppressWarnings("serial") static final class MapReduceValuesToIntTask<K,V>
6811 +        extends Traverser<K,V,Integer> {
6812 +        final ToIntFunction<? super V> transformer;
6813 +        final IntBinaryOperator reducer;
6814 +        final int basis;
6815 +        int result;
6816 +        MapReduceValuesToIntTask<K,V> rights, nextRight;
6817 +        MapReduceValuesToIntTask
6818 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6819 +             MapReduceValuesToIntTask<K,V> nextRight,
6820 +             ToIntFunction<? super V> transformer,
6821 +             int basis,
6822 +             IntBinaryOperator reducer) {
6823 +            super(m, p, b); this.nextRight = nextRight;
6824 +            this.transformer = transformer;
6825 +            this.basis = basis; this.reducer = reducer;
6826 +        }
6827 +        public final Integer getRawResult() { return result; }
6828 +        @SuppressWarnings("unchecked") public final void compute() {
6829 +            final ToIntFunction<? super V> transformer;
6830 +            final IntBinaryOperator reducer;
6831 +            if ((transformer = this.transformer) != null &&
6832 +                (reducer = this.reducer) != null) {
6833 +                int r = this.basis;
6834 +                for (int b; (b = preSplit()) > 0;)
6835 +                    (rights = new MapReduceValuesToIntTask<K,V>
6836 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6837 +                V v;
6838 +                while ((v = advanceValue()) != null)
6839 +                    r = reducer.applyAsInt(r, transformer.applyAsInt(v));
6840 +                result = r;
6841 +                CountedCompleter<?> c;
6842 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6843 +                    MapReduceValuesToIntTask<K,V>
6844 +                        t = (MapReduceValuesToIntTask<K,V>)c,
6845 +                        s = t.rights;
6846 +                    while (s != null) {
6847 +                        t.result = reducer.applyAsInt(t.result, s.result);
6848 +                        s = t.rights = s.nextRight;
6849 +                    }
6850 +                }
6851 +            }
6852 +        }
6853 +    }
6854 +
6855 +    @SuppressWarnings("serial") static final class MapReduceEntriesToIntTask<K,V>
6856 +        extends Traverser<K,V,Integer> {
6857 +        final ToIntFunction<Map.Entry<K,V>> transformer;
6858 +        final IntBinaryOperator reducer;
6859 +        final int basis;
6860 +        int result;
6861 +        MapReduceEntriesToIntTask<K,V> rights, nextRight;
6862 +        MapReduceEntriesToIntTask
6863 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6864 +             MapReduceEntriesToIntTask<K,V> nextRight,
6865 +             ToIntFunction<Map.Entry<K,V>> transformer,
6866 +             int basis,
6867 +             IntBinaryOperator reducer) {
6868 +            super(m, p, b); this.nextRight = nextRight;
6869 +            this.transformer = transformer;
6870 +            this.basis = basis; this.reducer = reducer;
6871 +        }
6872 +        public final Integer getRawResult() { return result; }
6873 +        @SuppressWarnings("unchecked") public final void compute() {
6874 +            final ToIntFunction<Map.Entry<K,V>> transformer;
6875 +            final IntBinaryOperator reducer;
6876 +            if ((transformer = this.transformer) != null &&
6877 +                (reducer = this.reducer) != null) {
6878 +                int r = this.basis;
6879 +                for (int b; (b = preSplit()) > 0;)
6880 +                    (rights = new MapReduceEntriesToIntTask<K,V>
6881 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6882 +                V v;
6883 +                while ((v = advanceValue()) != null)
6884 +                    r = reducer.applyAsInt(r, transformer.applyAsInt(entryFor(nextKey,
6885 +                                                                    v)));
6886 +                result = r;
6887 +                CountedCompleter<?> c;
6888 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6889 +                    MapReduceEntriesToIntTask<K,V>
6890 +                        t = (MapReduceEntriesToIntTask<K,V>)c,
6891 +                        s = t.rights;
6892 +                    while (s != null) {
6893 +                        t.result = reducer.applyAsInt(t.result, s.result);
6894 +                        s = t.rights = s.nextRight;
6895 +                    }
6896 +                }
6897 +            }
6898 +        }
6899 +    }
6900 +
6901 +    @SuppressWarnings("serial") static final class MapReduceMappingsToIntTask<K,V>
6902 +        extends Traverser<K,V,Integer> {
6903 +        final ToIntBiFunction<? super K, ? super V> transformer;
6904 +        final IntBinaryOperator reducer;
6905 +        final int basis;
6906 +        int result;
6907 +        MapReduceMappingsToIntTask<K,V> rights, nextRight;
6908 +        MapReduceMappingsToIntTask
6909 +            (ConcurrentHashMap<K,V> m, Traverser<K,V,?> p, int b,
6910 +             MapReduceMappingsToIntTask<K,V> nextRight,
6911 +             ToIntBiFunction<? super K, ? super V> transformer,
6912 +             int basis,
6913 +             IntBinaryOperator reducer) {
6914 +            super(m, p, b); this.nextRight = nextRight;
6915 +            this.transformer = transformer;
6916 +            this.basis = basis; this.reducer = reducer;
6917 +        }
6918 +        public final Integer getRawResult() { return result; }
6919 +        @SuppressWarnings("unchecked") public final void compute() {
6920 +            final ToIntBiFunction<? super K, ? super V> transformer;
6921 +            final IntBinaryOperator reducer;
6922 +            if ((transformer = this.transformer) != null &&
6923 +                (reducer = this.reducer) != null) {
6924 +                int r = this.basis;
6925 +                for (int b; (b = preSplit()) > 0;)
6926 +                    (rights = new MapReduceMappingsToIntTask<K,V>
6927 +                     (map, this, b, rights, transformer, r, reducer)).fork();
6928 +                V v;
6929 +                while ((v = advanceValue()) != null)
6930 +                    r = reducer.applyAsInt(r, transformer.applyAsInt(nextKey, v));
6931 +                result = r;
6932 +                CountedCompleter<?> c;
6933 +                for (c = firstComplete(); c != null; c = c.nextComplete()) {
6934 +                    MapReduceMappingsToIntTask<K,V>
6935 +                        t = (MapReduceMappingsToIntTask<K,V>)c,
6936 +                        s = t.rights;
6937 +                    while (s != null) {
6938 +                        t.result = reducer.applyAsInt(t.result, s.result);
6939 +                        s = t.rights = s.nextRight;
6940 +                    }
6941 +                }
6942 +            }
6943 +        }
6944 +    }
6945 +
6946 +    // Unsafe mechanics
6947 +    private static final sun.misc.Unsafe U;
6948 +    private static final long SIZECTL;
6949 +    private static final long TRANSFERINDEX;
6950 +    private static final long TRANSFERORIGIN;
6951 +    private static final long BASECOUNT;
6952 +    private static final long CELLSBUSY;
6953 +    private static final long CELLVALUE;
6954 +    private static final long ABASE;
6955 +    private static final int ASHIFT;
6956 +
6957 +    static {
6958 +        try {
6959 +            U = sun.misc.Unsafe.getUnsafe();
6960 +            Class<?> k = ConcurrentHashMap.class;
6961 +            SIZECTL = U.objectFieldOffset
6962 +                (k.getDeclaredField("sizeCtl"));
6963 +            TRANSFERINDEX = U.objectFieldOffset
6964 +                (k.getDeclaredField("transferIndex"));
6965 +            TRANSFERORIGIN = U.objectFieldOffset
6966 +                (k.getDeclaredField("transferOrigin"));
6967 +            BASECOUNT = U.objectFieldOffset
6968 +                (k.getDeclaredField("baseCount"));
6969 +            CELLSBUSY = U.objectFieldOffset
6970 +                (k.getDeclaredField("cellsBusy"));
6971 +            Class<?> ck = Cell.class;
6972 +            CELLVALUE = U.objectFieldOffset
6973 +                (ck.getDeclaredField("value"));
6974 +            Class<?> sc = Node[].class;
6975 +            ABASE = U.arrayBaseOffset(sc);
6976 +            int scale = U.arrayIndexScale(sc);
6977 +            if ((scale & (scale - 1)) != 0)
6978 +                throw new Error("data type scale not a power of two");
6979 +            ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6980 +        } catch (Exception e) {
6981 +            throw new Error(e);
6982 +        }
6983 +    }
6984 +
6985 + }

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