ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/jsr166/jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java
(Generate patch)

Comparing jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java (file contents):
Revision 1.24 by dl, Fri Oct 10 23:51:28 2003 UTC vs.
Revision 1.184 by jsr166, Fri Feb 15 21:45:40 2013 UTC

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

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines