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Revision 1.52 by dl, Mon Jul 12 11:01:14 2004 UTC vs.
Revision 1.242 by jsr166, Thu Aug 8 20:12:09 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, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
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	>
9	>	import java.io.ObjectStreamField;
10		import java.io.Serializable;
11	<	import java.io.IOException;
12	<	import java.io.ObjectInputStream;
13	<	import java.io.ObjectOutputStream;
11	>	import java.lang.reflect.ParameterizedType;
12	>	import java.lang.reflect.Type;
13	>	import java.util.AbstractMap;
14	>	import java.util.Arrays;
15	>	import java.util.Collection;
16	>	import java.util.Comparator;
17	>	import java.util.Enumeration;
18	>	import java.util.HashMap;
19	>	import java.util.Hashtable;
20	>	import java.util.Iterator;
21	>	import java.util.Map;
22	>	import java.util.NoSuchElementException;
23	>	import java.util.Set;
24	>	import java.util.Spliterator;
25	>	import java.util.concurrent.ConcurrentMap;
26	>	import java.util.concurrent.ForkJoinPool;
27	>	import java.util.concurrent.atomic.AtomicReference;
28	>	import java.util.concurrent.locks.LockSupport;
29	>	import java.util.concurrent.locks.ReentrantLock;
30	>	import java.util.function.BiConsumer;
31	>	import java.util.function.BiFunction;
32	>	import java.util.function.BinaryOperator;
33	>	import java.util.function.Consumer;
34	>	import java.util.function.DoubleBinaryOperator;
35	>	import java.util.function.Function;
36	>	import java.util.function.IntBinaryOperator;
37	>	import java.util.function.LongBinaryOperator;
38	>	import java.util.function.ToDoubleBiFunction;
39	>	import java.util.function.ToDoubleFunction;
40	>	import java.util.function.ToIntBiFunction;
41	>	import java.util.function.ToIntFunction;
42	>	import java.util.function.ToLongBiFunction;
43	>	import java.util.function.ToLongFunction;
44	>	import java.util.stream.Stream;
45
46		/**
47		* A hash table supporting full concurrency of retrievals and
48	<	* adjustable expected concurrency for updates. This class obeys the
48	>	* high expected concurrency for updates. This class obeys the
49		* same functional specification as {@link java.util.Hashtable}, and
50		* includes versions of methods corresponding to each method of
51	<	* <tt>Hashtable</tt>. However, even though all operations are
51	>	* {@code Hashtable}. However, even though all operations are
52		* thread-safe, retrieval operations do <em>not</em> entail locking,
53		* and there is <em>not</em> any support for locking the entire table
54		* in a way that prevents all access.  This class is fully
55	<	* interoperable with <tt>Hashtable</tt> in programs that rely on its
55	>	* interoperable with {@code Hashtable} in programs that rely on its
56		* thread safety but not on its synchronization details.
57		*
58	<	* <p> Retrieval operations (including <tt>get</tt>) generally do not
59	<	* block, so may overlap with update operations (including
60	<	* <tt>put</tt> and <tt>remove</tt>). Retrievals reflect the results
61	<	* of the most recently <em>completed</em> update operations holding
62	<	* upon their onset.  For aggregate operations such as <tt>putAll</tt>
63	<	* and <tt>clear</tt>, concurrent retrievals may reflect insertion or
64	<	* removal of only some entries.  Similarly, Iterators and
65	<	* Enumerations return elements reflecting the state of the hash table
66	<	* at some point at or since the creation of the iterator/enumeration.
67	<	* They do <em>not</em> throw
68	<	* {@link ConcurrentModificationException}.  However, iterators are
69	<	* designed to be used by only one thread at a time.
70	<	*
71	<	* <p> The allowed concurrency among update operations is guided by
72	<	* the optional <tt>concurrencyLevel</tt> constructor argument
73	<	* (default 16), which is used as a hint for internal sizing.  The
74	<	* table is internally partitioned to try to permit the indicated
75	<	* number of concurrent updates without contention. Because placement
76	<	* in hash tables is essentially random, the actual concurrency will
77	<	* vary.  Ideally, you should choose a value to accommodate as many
78	<	* threads as will ever concurrently modify the table. Using a
79	<	* significantly higher value than you need can waste space and time,
80	<	* and a significantly lower value can lead to thread contention. But
81	<	* overestimates and underestimates within an order of magnitude do
82	<	* not usually have much noticeable impact. A value of one is
83	<	* appropriate when it is known that only one thread will modify and
84	<	* all others will only read. Also, resizing this or any other kind of
85	<	* hash table is a relatively slow operation, so, when possible, it is
86	<	* a good idea to provide estimates of expected table sizes in
87	<	* constructors.
58	>	* <p>Retrieval operations (including {@code get}) generally do not
59	>	* block, so may overlap with update operations (including {@code put}
60	>	* and {@code remove}). Retrievals reflect the results of the most
61	>	* recently <em>completed</em> update operations holding upon their
62	>	* onset. (More formally, an update operation for a given key bears a
63	>	* <em>happens-before</em> relation with any (non-null) retrieval for
64	>	* that key reporting the updated value.)  For aggregate operations
65	>	* such as {@code putAll} and {@code clear}, concurrent retrievals may
66	>	* reflect insertion or removal of only some entries.  Similarly,
67	>	* Iterators, Spliterators and Enumerations return elements reflecting the
68	>	* state of the hash table at some point at or since the creation of the
69	>	* iterator/enumeration.  They do <em>not</em> throw {@link
70	>	* java.util.ConcurrentModificationException ConcurrentModificationException}.
71	>	* However, iterators are designed to be used by only one thread at a time.
72	>	* Bear in mind that the results of aggregate status methods including
73	>	* {@code size}, {@code isEmpty}, and {@code containsValue} are typically
74	>	* useful only when a map is not undergoing concurrent updates in other threads.
75	>	* Otherwise the results of these methods reflect transient states
76	>	* that may be adequate for monitoring or estimation purposes, but not
77	>	* for program control.
78	>	*
79	>	* <p>The table is dynamically expanded when there are too many
80	>	* collisions (i.e., keys that have distinct hash codes but fall into
81	>	* the same slot modulo the table size), with the expected average
82	>	* effect of maintaining roughly two bins per mapping (corresponding
83	>	* to a 0.75 load factor threshold for resizing). There may be much
84	>	* variance around this average as mappings are added and removed, but
85	>	* overall, this maintains a commonly accepted time/space tradeoff for
86	>	* hash tables.  However, resizing this or any other kind of hash
87	>	* table may be a relatively slow operation. When possible, it is a
88	>	* good idea to provide a size estimate as an optional {@code
89	>	* initialCapacity} constructor argument. An additional optional
90	>	* {@code loadFactor} constructor argument provides a further means of
91	>	* customizing initial table capacity by specifying the table density
92	>	* to be used in calculating the amount of space to allocate for the
93	>	* given number of elements.  Also, for compatibility with previous
94	>	* versions of this class, constructors may optionally specify an
95	>	* expected {@code concurrencyLevel} as an additional hint for
96	>	* internal sizing.  Note that using many keys with exactly the same
97	>	* {@code hashCode()} is a sure way to slow down performance of any
98	>	* hash table. To ameliorate impact, when keys are {@link Comparable},
99	>	* this class may use comparison order among keys to help break ties.
100	>	*
101	>	* <p>A {@link Set} projection of a ConcurrentHashMap may be created
102	>	* (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed
103	>	* (using {@link #keySet(Object)} when only keys are of interest, and the
104	>	* mapped values are (perhaps transiently) not used or all take the
105	>	* same mapping value.
106	>	*
107	>	* <p>A ConcurrentHashMap can be used as scalable frequency map (a
108	>	* form of histogram or multiset) by using {@link
109	>	* java.util.concurrent.atomic.LongAdder} values and initializing via
110	>	* {@link #computeIfAbsent computeIfAbsent}. For example, to add a count
111	>	* to a {@code ConcurrentHashMap<String,LongAdder> freqs}, you can use
112	>	* {@code freqs.computeIfAbsent(k -> new LongAdder()).increment();}
113		*
114		* <p>This class and its views and iterators implement all of the
115		* <em>optional</em> methods of the {@link Map} and {@link Iterator}
116		* interfaces.
117		*
118	<	* <p> Like {@link java.util.Hashtable} but unlike {@link
119	<	* java.util.HashMap}, this class does NOT allow <tt>null</tt> to be
120	<	* used as a key or value.
118	>	* <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
119	>	* does <em>not</em> allow {@code null} to be used as a key or value.
120	>	*
121	>	* <p>ConcurrentHashMaps support a set of sequential and parallel bulk
122	>	* operations that, unlike most {@link Stream} methods, are designed
123	>	* to be safely, and often sensibly, applied even with maps that are
124	>	* being concurrently updated by other threads; for example, when
125	>	* computing a snapshot summary of the values in a shared registry.
126	>	* There are three kinds of operation, each with four forms, accepting
127	>	* functions with Keys, Values, Entries, and (Key, Value) arguments
128	>	* and/or return values. Because the elements of a ConcurrentHashMap
129	>	* are not ordered in any particular way, and may be processed in
130	>	* different orders in different parallel executions, the correctness
131	>	* of supplied functions should not depend on any ordering, or on any
132	>	* other objects or values that may transiently change while
133	>	* computation is in progress; and except for forEach actions, should
134	>	* ideally be side-effect-free. Bulk operations on {@link java.util.Map.Entry}
135	>	* objects do not support method {@code setValue}.
136	>	*
137	>	* <ul>
138	>	* <li> forEach: Perform a given action on each element.
139	>	* A variant form applies a given transformation on each element
140	>	* before performing the action.</li>
141	>	*
142	>	* <li> search: Return the first available non-null result of
143	>	* applying a given function on each element; skipping further
144	>	* search when a result is found.</li>
145	>	*
146	>	* <li> reduce: Accumulate each element.  The supplied reduction
147	>	* function cannot rely on ordering (more formally, it should be
148	>	* both associative and commutative).  There are five variants:
149	>	*
150	>	* <ul>
151	>	*
152	>	* <li> Plain reductions. (There is not a form of this method for
153	>	* (key, value) function arguments since there is no corresponding
154	>	* return type.)</li>
155	>	*
156	>	* <li> Mapped reductions that accumulate the results of a given
157	>	* function applied to each element.</li>
158	>	*
159	>	* <li> Reductions to scalar doubles, longs, and ints, using a
160	>	* given basis value.</li>
161	>	*
162	>	* </ul>
163	>	* </li>
164	>	* </ul>
165	>	*
166	>	* <p>These bulk operations accept a {@code parallelismThreshold}
167	>	* argument. Methods proceed sequentially if the current map size is
168	>	* estimated to be less than the given threshold. Using a value of
169	>	* {@code Long.MAX_VALUE} suppresses all parallelism.  Using a value
170	>	* of {@code 1} results in maximal parallelism by partitioning into
171	>	* enough subtasks to fully utilize the {@link
172	>	* ForkJoinPool#commonPool()} that is used for all parallel
173	>	* computations. Normally, you would initially choose one of these
174	>	* extreme values, and then measure performance of using in-between
175	>	* values that trade off overhead versus throughput.
176	>	*
177	>	* <p>The concurrency properties of bulk operations follow
178	>	* from those of ConcurrentHashMap: Any non-null result returned
179	>	* from {@code get(key)} and related access methods bears a
180	>	* happens-before relation with the associated insertion or
181	>	* update.  The result of any bulk operation reflects the
182	>	* composition of these per-element relations (but is not
183	>	* necessarily atomic with respect to the map as a whole unless it
184	>	* is somehow known to be quiescent).  Conversely, because keys
185	>	* and values in the map are never null, null serves as a reliable
186	>	* atomic indicator of the current lack of any result.  To
187	>	* maintain this property, null serves as an implicit basis for
188	>	* all non-scalar reduction operations. For the double, long, and
189	>	* int versions, the basis should be one that, when combined with
190	>	* any other value, returns that other value (more formally, it
191	>	* should be the identity element for the reduction). Most common
192	>	* reductions have these properties; for example, computing a sum
193	>	* with basis 0 or a minimum with basis MAX_VALUE.
194	>	*
195	>	* <p>Search and transformation functions provided as arguments
196	>	* should similarly return null to indicate the lack of any result
197	>	* (in which case it is not used). In the case of mapped
198	>	* reductions, this also enables transformations to serve as
199	>	* filters, returning null (or, in the case of primitive
200	>	* specializations, the identity basis) if the element should not
201	>	* be combined. You can create compound transformations and
202	>	* filterings by composing them yourself under this "null means
203	>	* there is nothing there now" rule before using them in search or
204	>	* reduce operations.
205	>	*
206	>	* <p>Methods accepting and/or returning Entry arguments maintain
207	>	* key-value associations. They may be useful for example when
208	>	* finding the key for the greatest value. Note that "plain" Entry
209	>	* arguments can be supplied using {@code new
210	>	* AbstractMap.SimpleEntry(k,v)}.
211	>	*
212	>	* <p>Bulk operations may complete abruptly, throwing an
213	>	* exception encountered in the application of a supplied
214	>	* function. Bear in mind when handling such exceptions that other
215	>	* concurrently executing functions could also have thrown
216	>	* exceptions, or would have done so if the first exception had
217	>	* not occurred.
218	>	*
219	>	* <p>Speedups for parallel compared to sequential forms are common
220	>	* but not guaranteed.  Parallel operations involving brief functions
221	>	* on small maps may execute more slowly than sequential forms if the
222	>	* underlying work to parallelize the computation is more expensive
223	>	* than the computation itself.  Similarly, parallelization may not
224	>	* lead to much actual parallelism if all processors are busy
225	>	* performing unrelated tasks.
226	>	*
227	>	* <p>All arguments to all task methods must be non-null.
228		*
229		* <p>This class is a member of the
230	<	* <a href="{@docRoot}/../guide/collections/index.html">
230	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
231		* Java Collections Framework</a>.
232		*
233		* @since 1.5
234		* @author Doug Lea
235		* @param <K> the type of keys maintained by this map
236	<	* @param <V> the type of mapped values
236	>	* @param <V> the type of mapped values
237		*/
238	<	public class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
239	<	implements ConcurrentMap<K, V>, Serializable {
238	>	public class ConcurrentHashMap<K,V> extends AbstractMap<K,V>
239	>	implements ConcurrentMap<K,V>, Serializable {
240		private static final long serialVersionUID = 7249069246763182397L;
241
242		/*
243	<	* The basic strategy is to subdivide the table among Segments,
244	<	* each of which itself is a concurrently readable hash table.
243	>	* Overview:
244	>	*
245	>	* The primary design goal of this hash table is to maintain
246	>	* concurrent readability (typically method get(), but also
247	>	* iterators and related methods) while minimizing update
248	>	* contention. Secondary goals are to keep space consumption about
249	>	* the same or better than java.util.HashMap, and to support high
250	>	* initial insertion rates on an empty table by many threads.
251	>	*
252	>	* This map usually acts as a binned (bucketed) hash table.  Each
253	>	* key-value mapping is held in a Node.  Most nodes are instances
254	>	* of the basic Node class with hash, key, value, and next
255	>	* fields. However, various subclasses exist: TreeNodes are
256	>	* arranged in balanced trees, not lists.  TreeBins hold the roots
257	>	* of sets of TreeNodes. ForwardingNodes are placed at the heads
258	>	* of bins during resizing. ReservationNodes are used as
259	>	* placeholders while establishing values in computeIfAbsent and
260	>	* related methods.  The types TreeBin, ForwardingNode, and
261	>	* ReservationNode do not hold normal user keys, values, or
262	>	* hashes, and are readily distinguishable during search etc
263	>	* because they have negative hash fields and null key and value
264	>	* fields. (These special nodes are either uncommon or transient,
265	>	* so the impact of carrying around some unused fields is
266	>	* insignificant.)
267	>	*
268	>	* The table is lazily initialized to a power-of-two size upon the
269	>	* first insertion.  Each bin in the table normally contains a
270	>	* list of Nodes (most often, the list has only zero or one Node).
271	>	* Table accesses require volatile/atomic reads, writes, and
272	>	* CASes.  Because there is no other way to arrange this without
273	>	* adding further indirections, we use intrinsics
274	>	* (sun.misc.Unsafe) operations.
275	>	*
276	>	* We use the top (sign) bit of Node hash fields for control
277	>	* purposes -- it is available anyway because of addressing
278	>	* constraints.  Nodes with negative hash fields are specially
279	>	* handled or ignored in map methods.
280	>	*
281	>	* Insertion (via put or its variants) of the first node in an
282	>	* empty bin is performed by just CASing it to the bin.  This is
283	>	* by far the most common case for put operations under most
284	>	* key/hash distributions.  Other update operations (insert,
285	>	* delete, and replace) require locks.  We do not want to waste
286	>	* the space required to associate a distinct lock object with
287	>	* each bin, so instead use the first node of a bin list itself as
288	>	* a lock. Locking support for these locks relies on builtin
289	>	* "synchronized" monitors.
290	>	*
291	>	* Using the first node of a list as a lock does not by itself
292	>	* suffice though: When a node is locked, any update must first
293	>	* validate that it is still the first node after locking it, and
294	>	* retry if not. Because new nodes are always appended to lists,
295	>	* once a node is first in a bin, it remains first until deleted
296	>	* or the bin becomes invalidated (upon resizing).
297	>	*
298	>	* The main disadvantage of per-bin locks is that other update
299	>	* operations on other nodes in a bin list protected by the same
300	>	* lock can stall, for example when user equals() or mapping
301	>	* functions take a long time.  However, statistically, under
302	>	* random hash codes, this is not a common problem.  Ideally, the
303	>	* frequency of nodes in bins follows a Poisson distribution
304	>	* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
305	>	* parameter of about 0.5 on average, given the resizing threshold
306	>	* of 0.75, although with a large variance because of resizing
307	>	* granularity. Ignoring variance, the expected occurrences of
308	>	* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
309	>	* first values are:
310	>	*
311	>	* 0:    0.60653066
312	>	* 1:    0.30326533
313	>	* 2:    0.07581633
314	>	* 3:    0.01263606
315	>	* 4:    0.00157952
316	>	* 5:    0.00015795
317	>	* 6:    0.00001316
318	>	* 7:    0.00000094
319	>	* 8:    0.00000006
320	>	* more: less than 1 in ten million
321	>	*
322	>	* Lock contention probability for two threads accessing distinct
323	>	* elements is roughly 1 / (8 * #elements) under random hashes.
324	>	*
325	>	* Actual hash code distributions encountered in practice
326	>	* sometimes deviate significantly from uniform randomness.  This
327	>	* includes the case when N > (1<<30), so some keys MUST collide.
328	>	* Similarly for dumb or hostile usages in which multiple keys are
329	>	* designed to have identical hash codes or ones that differs only
330	>	* in masked-out high bits. So we use a secondary strategy that
331	>	* applies when the number of nodes in a bin exceeds a
332	>	* threshold. These TreeBins use a balanced tree to hold nodes (a
333	>	* specialized form of red-black trees), bounding search time to
334	>	* O(log N).  Each search step in a TreeBin is at least twice as
335	>	* slow as in a regular list, but given that N cannot exceed
336	>	* (1<<64) (before running out of addresses) this bounds search
337	>	* steps, lock hold times, etc, to reasonable constants (roughly
338	>	* 100 nodes inspected per operation worst case) so long as keys
339	>	* are Comparable (which is very common -- String, Long, etc).
340	>	* TreeBin nodes (TreeNodes) also maintain the same "next"
341	>	* traversal pointers as regular nodes, so can be traversed in
342	>	* iterators in the same way.
343	>	*
344	>	* The table is resized when occupancy exceeds a percentage
345	>	* threshold (nominally, 0.75, but see below).  Any thread
346	>	* noticing an overfull bin may assist in resizing after the
347	>	* initiating thread allocates and sets up the replacement
348	>	* array. However, rather than stalling, these other threads may
349	>	* proceed with insertions etc.  The use of TreeBins shields us
350	>	* from the worst case effects of overfilling while resizes are in
351	>	* progress.  Resizing proceeds by transferring bins, one by one,
352	>	* from the table to the next table. To enable concurrency, the
353	>	* next table must be (incrementally) prefilled with place-holders
354	>	* serving as reverse forwarders to the old table.  Because we are
355	>	* using power-of-two expansion, the elements from each bin must
356	>	* either stay at same index, or move with a power of two
357	>	* offset. We eliminate unnecessary node creation by catching
358	>	* cases where old nodes can be reused because their next fields
359	>	* won't change.  On average, only about one-sixth of them need
360	>	* cloning when a table doubles. The nodes they replace will be
361	>	* garbage collectable as soon as they are no longer referenced by
362	>	* any reader thread that may be in the midst of concurrently
363	>	* traversing table.  Upon transfer, the old table bin contains
364	>	* only a special forwarding node (with hash field "MOVED") that
365	>	* contains the next table as its key. On encountering a
366	>	* forwarding node, access and update operations restart, using
367	>	* the new table.
368	>	*
369	>	* Each bin transfer requires its bin lock, which can stall
370	>	* waiting for locks while resizing. However, because other
371	>	* threads can join in and help resize rather than contend for
372	>	* locks, average aggregate waits become shorter as resizing
373	>	* progresses.  The transfer operation must also ensure that all
374	>	* accessible bins in both the old and new table are usable by any
375	>	* traversal.  This is arranged by proceeding from the last bin
376	>	* (table.length - 1) up towards the first.  Upon seeing a
377	>	* forwarding node, traversals (see class Traverser) arrange to
378	>	* move to the new table without revisiting nodes.  However, to
379	>	* ensure that no intervening nodes are skipped, bin splitting can
380	>	* only begin after the associated reverse-forwarders are in
381	>	* place.
382	>	*
383	>	* The traversal scheme also applies to partial traversals of
384	>	* ranges of bins (via an alternate Traverser constructor)
385	>	* to support partitioned aggregate operations.  Also, read-only
386	>	* operations give up if ever forwarded to a null table, which
387	>	* provides support for shutdown-style clearing, which is also not
388	>	* currently implemented.
389	>	*
390	>	* Lazy table initialization minimizes footprint until first use,
391	>	* and also avoids resizings when the first operation is from a
392	>	* putAll, constructor with map argument, or deserialization.
393	>	* These cases attempt to override the initial capacity settings,
394	>	* but harmlessly fail to take effect in cases of races.
395	>	*
396	>	* The element count is maintained using a specialization of
397	>	* LongAdder. We need to incorporate a specialization rather than
398	>	* just use a LongAdder in order to access implicit
399	>	* contention-sensing that leads to creation of multiple
400	>	* CounterCells.  The counter mechanics avoid contention on
401	>	* updates but can encounter cache thrashing if read too
402	>	* frequently during concurrent access. To avoid reading so often,
403	>	* resizing under contention is attempted only upon adding to a
404	>	* bin already holding two or more nodes. Under uniform hash
405	>	* distributions, the probability of this occurring at threshold
406	>	* is around 13%, meaning that only about 1 in 8 puts check
407	>	* threshold (and after resizing, many fewer do so).
408	>	*
409	>	* TreeBins use a special form of comparison for search and
410	>	* related operations (which is the main reason we cannot use
411	>	* existing collections such as TreeMaps). TreeBins contain
412	>	* Comparable elements, but may contain others, as well as
413	>	* elements that are Comparable but not necessarily Comparable for
414	>	* the same T, so we cannot invoke compareTo among them. To handle
415	>	* this, the tree is ordered primarily by hash value, then by
416	>	* Comparable.compareTo order if applicable.  On lookup at a node,
417	>	* if elements are not comparable or compare as 0 then both left
418	>	* and right children may need to be searched in the case of tied
419	>	* hash values. (This corresponds to the full list search that
420	>	* would be necessary if all elements were non-Comparable and had
421	>	* tied hashes.) On insertion, to keep a total ordering (or as
422	>	* close as is required here) across rebalancings, we compare
423	>	* classes and identityHashCodes as tie-breakers. The red-black
424	>	* balancing code is updated from pre-jdk-collections
425	>	* (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
426	>	* based in turn on Cormen, Leiserson, and Rivest "Introduction to
427	>	* Algorithms" (CLR).
428	>	*
429	>	* TreeBins also require an additional locking mechanism.  While
430	>	* list traversal is always possible by readers even during
431	>	* updates, tree traversal is not, mainly because of tree-rotations
432	>	* that may change the root node and/or its linkages.  TreeBins
433	>	* include a simple read-write lock mechanism parasitic on the
434	>	* main bin-synchronization strategy: Structural adjustments
435	>	* associated with an insertion or removal are already bin-locked
436	>	* (and so cannot conflict with other writers) but must wait for
437	>	* ongoing readers to finish. Since there can be only one such
438	>	* waiter, we use a simple scheme using a single "waiter" field to
439	>	* block writers.  However, readers need never block.  If the root
440	>	* lock is held, they proceed along the slow traversal path (via
441	>	* next-pointers) until the lock becomes available or the list is
442	>	* exhausted, whichever comes first. These cases are not fast, but
443	>	* maximize aggregate expected throughput.
444	>	*
445	>	* Maintaining API and serialization compatibility with previous
446	>	* versions of this class introduces several oddities. Mainly: We
447	>	* leave untouched but unused constructor arguments refering to
448	>	* concurrencyLevel. We accept a loadFactor constructor argument,
449	>	* but apply it only to initial table capacity (which is the only
450	>	* time that we can guarantee to honor it.) We also declare an
451	>	* unused "Segment" class that is instantiated in minimal form
452	>	* only when serializing.
453	>	*
454	>	* Also, solely for compatibility with previous versions of this
455	>	* class, it extends AbstractMap, even though all of its methods
456	>	* are overridden, so it is just useless baggage.
457	>	*
458	>	* This file is organized to make things a little easier to follow
459	>	* while reading than they might otherwise: First the main static
460	>	* declarations and utilities, then fields, then main public
461	>	* methods (with a few factorings of multiple public methods into
462	>	* internal ones), then sizing methods, trees, traversers, and
463	>	* bulk operations.
464		*/
465
466		/* ---------------- Constants -------------- */
467
468		/**
469	<	* The default initial number of table slots for this table.
470	<	* Used when not otherwise specified in constructor.
469	>	* The largest possible table capacity.  This value must be
470	>	* exactly 1<<30 to stay within Java array allocation and indexing
471	>	* bounds for power of two table sizes, and is further required
472	>	* because the top two bits of 32bit hash fields are used for
473	>	* control purposes.
474		*/
475	<	static int DEFAULT_INITIAL_CAPACITY = 16;
475	>	private static final int MAXIMUM_CAPACITY = 1 << 30;
476
477		/**
478	<	* The maximum capacity, used if a higher value is implicitly
479	<	* specified by either of the constructors with arguments.  MUST
95	<	* be a power of two <= 1<<30 to ensure that entries are indexible
96	<	* using ints.
478	>	* The default initial table capacity.  Must be a power of 2
479	>	* (i.e., at least 1) and at most MAXIMUM_CAPACITY.
480		*/
481	<	static final int MAXIMUM_CAPACITY = 1 << 30;
481	>	private static final int DEFAULT_CAPACITY = 16;
482
483		/**
484	<	* The default load factor for this table.  Used when not
485	<	* otherwise specified in constructor.
484	>	* The largest possible (non-power of two) array size.
485	>	* Needed by toArray and related methods.
486		*/
487	<	static final float DEFAULT_LOAD_FACTOR = 0.75f;
487	>	static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
488
489		/**
490	<	* The default number of concurrency control segments.
491	<	**/
492	<	static final int DEFAULT_SEGMENTS = 16;
490	>	* The default concurrency level for this table. Unused but
491	>	* defined for compatibility with previous versions of this class.
492	>	*/
493	>	private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
494
495		/**
496	<	* The maximum number of segments to allow; used to bound
497	<	* constructor arguments.
496	>	* The load factor for this table. Overrides of this value in
497	>	* constructors affect only the initial table capacity.  The
498	>	* actual floating point value isn't normally used -- it is
499	>	* simpler to use expressions such as {@code n - (n >>> 2)} for
500	>	* the associated resizing threshold.
501		*/
502	<	static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
502	>	private static final float LOAD_FACTOR = 0.75f;
503
504		/**
505	<	* Number of unsynchronized retries in size and containsValue
506	<	* methods before resorting to locking. This is used to avoid
507	<	* unbounded retries if tables undergo continuous modification
508	<	* which would make it impossible to obtain an accurate result.
505	>	* The bin count threshold for using a tree rather than list for a
506	>	* bin.  Bins are converted to trees when adding an element to a
507	>	* bin with at least this many nodes. The value must be greater
508	>	* than 2, and should be at least 8 to mesh with assumptions in
509	>	* tree removal about conversion back to plain bins upon
510	>	* shrinkage.
511		*/
512	<	static final int RETRIES_BEFORE_LOCK = 2;
512	>	static final int TREEIFY_THRESHOLD = 8;
513
514	<	/* ---------------- Fields -------------- */
514	>	/**
515	>	* The bin count threshold for untreeifying a (split) bin during a
516	>	* resize operation. Should be less than TREEIFY_THRESHOLD, and at
517	>	* most 6 to mesh with shrinkage detection under removal.
518	>	*/
519	>	static final int UNTREEIFY_THRESHOLD = 6;
520
521		/**
522	<	* Mask value for indexing into segments. The upper bits of a
523	<	* key's hash code are used to choose the segment.
524	<	**/
525	<	final int segmentMask;
522	>	* The smallest table capacity for which bins may be treeified.
523	>	* (Otherwise the table is resized if too many nodes in a bin.)
524	>	* The value should be at least 4 * TREEIFY_THRESHOLD to avoid
525	>	* conflicts between resizing and treeification thresholds.
526	>	*/
527	>	static final int MIN_TREEIFY_CAPACITY = 64;
528
529		/**
530	<	* Shift value for indexing within segments.
531	<	**/
532	<	final int segmentShift;
530	>	* Minimum number of rebinnings per transfer step. Ranges are
531	>	* subdivided to allow multiple resizer threads.  This value
532	>	* serves as a lower bound to avoid resizers encountering
533	>	* excessive memory contention.  The value should be at least
534	>	* DEFAULT_CAPACITY.
535	>	*/
536	>	private static final int MIN_TRANSFER_STRIDE = 16;
537	>
538	>	/*
539	>	* Encodings for Node hash fields. See above for explanation.
540	>	*/
541	>	static final int MOVED     = -1; // hash for forwarding nodes
542	>	static final int TREEBIN   = -2; // hash for roots of trees
543	>	static final int RESERVED  = -3; // hash for transient reservations
544	>	static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
545	>
546	>	/** Number of CPUS, to place bounds on some sizings */
547	>	static final int NCPU = Runtime.getRuntime().availableProcessors();
548	>
549	>	/** For serialization compatibility. */
550	>	private static final ObjectStreamField[] serialPersistentFields = {
551	>	new ObjectStreamField("segments", Segment[].class),
552	>	new ObjectStreamField("segmentMask", Integer.TYPE),
553	>	new ObjectStreamField("segmentShift", Integer.TYPE)
554	>	};
555	>
556	>	/* ---------------- Nodes -------------- */
557
558		/**
559	<	* The segments, each of which is a specialized hash table
559	>	* Key-value entry.  This class is never exported out as a
560	>	* user-mutable Map.Entry (i.e., one supporting setValue; see
561	>	* MapEntry below), but can be used for read-only traversals used
562	>	* in bulk tasks.  Subclasses of Node with a negative hash field
563	>	* are special, and contain null keys and values (but are never
564	>	* exported).  Otherwise, keys and vals are never null.
565		*/
566	<	final Segment[] segments;
566	>	static class Node<K,V> implements Map.Entry<K,V> {
567	>	final int hash;
568	>	final K key;
569	>	volatile V val;
570	>	volatile Node<K,V> next;
571
572	<	transient Set<K> keySet;
573	<	transient Set<Map.Entry<K,V>> entrySet;
574	<	transient Collection<V> values;
572	>	Node(int hash, K key, V val, Node<K,V> next) {
573	>	this.hash = hash;
574	>	this.key = key;
575	>	this.val = val;
576	>	this.next = next;
577	>	}
578	>
579	>	public final K getKey()       { return key; }
580	>	public final V getValue()     { return val; }
581	>	public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
582	>	public final String toString(){ return key + "=" + val; }
583	>	public final V setValue(V value) {
584	>	throw new UnsupportedOperationException();
585	>	}
586	>
587	>	public final boolean equals(Object o) {
588	>	Object k, v, u; Map.Entry<?,?> e;
589	>	return ((o instanceof Map.Entry) &&
590	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
591	>	(v = e.getValue()) != null &&
592	>	(k == key || k.equals(key)) &&
593	>	(v == (u = val) || v.equals(u)));
594	>	}
595	>
596	>	/**
597	>	* Virtualized support for map.get(); overridden in subclasses.
598	>	*/
599	>	Node<K,V> find(int h, Object k) {
600	>	Node<K,V> e = this;
601	>	if (k != null) {
602	>	do {
603	>	K ek;
604	>	if (e.hash == h &&
605	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
606	>	return e;
607	>	} while ((e = e.next) != null);
608	>	}
609	>	return null;
610	>	}
611	>	}
612
613	<	/* ---------------- Small Utilities -------------- */
613	>	/* ---------------- Static utilities -------------- */
614
615		/**
616	<	* Returns a hash code for non-null Object x.
617	<	* Uses the same hash code spreader as most other java.util hash tables.
618	<	* @param x the object serving as a key
619	<	* @return the hash code
616	>	* Spreads (XORs) higher bits of hash to lower and also forces top
617	>	* bit to 0. Because the table uses power-of-two masking, sets of
618	>	* hashes that vary only in bits above the current mask will
619	>	* always collide. (Among known examples are sets of Float keys
620	>	* holding consecutive whole numbers in small tables.)  So we
621	>	* apply a transform that spreads the impact of higher bits
622	>	* downward. There is a tradeoff between speed, utility, and
623	>	* quality of bit-spreading. Because many common sets of hashes
624	>	* are already reasonably distributed (so don't benefit from
625	>	* spreading), and because we use trees to handle large sets of
626	>	* collisions in bins, we just XOR some shifted bits in the
627	>	* cheapest possible way to reduce systematic lossage, as well as
628	>	* to incorporate impact of the highest bits that would otherwise
629	>	* never be used in index calculations because of table bounds.
630		*/
631	<	static int hash(Object x) {
632	<	int h = x.hashCode();
157	<	h += ~(h << 9);
158	<	h ^=  (h >>> 14);
159	<	h +=  (h << 4);
160	<	h ^=  (h >>> 10);
161	<	return h;
631	>	static final int spread(int h) {
632	>	return (h ^ (h >>> 16)) & HASH_BITS;
633		}
634
635		/**
636	<	* Returns the segment that should be used for key with given hash
637	<	* @param hash the hash code for the key
167	<	* @return the segment
636	>	* Returns a power of two table size for the given desired capacity.
637	>	* See Hackers Delight, sec 3.2
638		*/
639	<	final Segment<K,V> segmentFor(int hash) {
640	<	return (Segment<K,V>) segments[(hash >>> segmentShift) & segmentMask];
639	>	private static final int tableSizeFor(int c) {
640	>	int n = c - 1;
641	>	n |= n >>> 1;
642	>	n |= n >>> 2;
643	>	n |= n >>> 4;
644	>	n |= n >>> 8;
645	>	n |= n >>> 16;
646	>	return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
647		}
648
649	<	/* ---------------- Inner Classes -------------- */
649	>	/**
650	>	* Returns x's Class if it is of the form "class C implements
651	>	* Comparable<C>", else null.
652	>	*/
653	>	static Class<?> comparableClassFor(Object x) {
654	>	if (x instanceof Comparable) {
655	>	Class<?> c; Type[] ts, as; Type t; ParameterizedType p;
656	>	if ((c = x.getClass()) == String.class) // bypass checks
657	>	return c;
658	>	if ((ts = c.getGenericInterfaces()) != null) {
659	>	for (int i = 0; i < ts.length; ++i) {
660	>	if (((t = ts[i]) instanceof ParameterizedType) &&
661	>	((p = (ParameterizedType)t).getRawType() ==
662	>	Comparable.class) &&
663	>	(as = p.getActualTypeArguments()) != null &&
664	>	as.length == 1 && as[0] == c) // type arg is c
665	>	return c;
666	>	}
667	>	}
668	>	}
669	>	return null;
670	>	}
671
672		/**
673	<	* ConcurrentHashMap list entry. Note that this is never exported
674	<	* out as a user-visible Map.Entry.
178	<	*
179	<	* Because the value field is volatile, not final, it is legal wrt
180	<	* the Java Memory Model for an unsynchronized reader to see null
181	<	* instead of initial value when read via a data race.  Although a
182	<	* reordering leading to this is not likely to ever actually
183	<	* occur, the Segment.readValueUnderLock method is used as a
184	<	* backup in case a null (pre-initialized) value is ever seen in
185	<	* an unsynchronized access method.
673	>	* Returns k.compareTo(x) if x matches kc (k's screened comparable
674	>	* class), else 0.
675		*/
676	<	static final class HashEntry<K,V> {
677	<	final K key;
678	<	final int hash;
679	<	volatile V value;
680	<	final HashEntry<K,V> next;
676	>	@SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
677	>	static int compareComparables(Class<?> kc, Object k, Object x) {
678	>	return (x == null || x.getClass() != kc ? 0 :
679	>	((Comparable)k).compareTo(x));
680	>	}
681
682	<	HashEntry(K key, int hash, HashEntry<K,V> next, V value) {
683	<	this.key = key;
684	<	this.hash = hash;
685	<	this.next = next;
686	<	this.value = value;
687	<	}
682	>	/* ---------------- Table element access -------------- */
683	>
684	>	/*
685	>	* Volatile access methods are used for table elements as well as
686	>	* elements of in-progress next table while resizing.  All uses of
687	>	* the tab arguments must be null checked by callers.  All callers
688	>	* also paranoically precheck that tab's length is not zero (or an
689	>	* equivalent check), thus ensuring that any index argument taking
690	>	* the form of a hash value anded with (length - 1) is a valid
691	>	* index.  Note that, to be correct wrt arbitrary concurrency
692	>	* errors by users, these checks must operate on local variables,
693	>	* which accounts for some odd-looking inline assignments below.
694	>	* Note that calls to setTabAt always occur within locked regions,
695	>	* and so in principle require only release ordering, not need
696	>	* full volatile semantics, but are currently coded as volatile
697	>	* writes to be conservative.
698	>	*/
699	>
700	>	@SuppressWarnings("unchecked")
701	>	static final <K,V> Node<K,V> tabAt(Node<K,V>[] tab, int i) {
702	>	return (Node<K,V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
703	>	}
704	>
705	>	static final <K,V> boolean casTabAt(Node<K,V>[] tab, int i,
706	>	Node<K,V> c, Node<K,V> v) {
707	>	return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
708	>	}
709	>
710	>	static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {
711	>	U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
712		}
713
714	+	/* ---------------- Fields -------------- */
715	+
716		/**
717	<	* Segments are specialized versions of hash tables.  This
718	<	* subclasses from ReentrantLock opportunistically, just to
719	<	* simplify some locking and avoid separate construction.
720	<	**/
206	<	static final class Segment<K,V> extends ReentrantLock implements Serializable {
207	<	/*
208	<	* Segments maintain a table of entry lists that are ALWAYS
209	<	* kept in a consistent state, so can be read without locking.
210	<	* Next fields of nodes are immutable (final).  All list
211	<	* additions are performed at the front of each bin. This
212	<	* makes it easy to check changes, and also fast to traverse.
213	<	* When nodes would otherwise be changed, new nodes are
214	<	* created to replace them. This works well for hash tables
215	<	* since the bin lists tend to be short. (The average length
216	<	* is less than two for the default load factor threshold.)
217	<	*
218	<	* Read operations can thus proceed without locking, but rely
219	<	* on selected uses of volatiles to ensure that completed
220	<	* write operations performed by other threads are
221	<	* noticed. For most purposes, the "count" field, tracking the
222	<	* number of elements, serves as that volatile variable
223	<	* ensuring visibility.  This is convenient because this field
224	<	* needs to be read in many read operations anyway:
225	<	*
226	<	*   - All (unsynchronized) read operations must first read the
227	<	*     "count" field, and should not look at table entries if
228	<	*     it is 0.
229	<	*
230	<	*   - All (synchronized) write operations should write to
231	<	*     the "count" field after structurally changing any bin.
232	<	*     The operations must not take any action that could even
233	<	*     momentarily cause a concurrent read operation to see
234	<	*     inconsistent data. This is made easier by the nature of
235	<	*     the read operations in Map. For example, no operation
236	<	*     can reveal that the table has grown but the threshold
237	<	*     has not yet been updated, so there are no atomicity
238	<	*     requirements for this with respect to reads.
239	<	*
240	<	* As a guide, all critical volatile reads and writes to the
241	<	* count field are marked in code comments.
242	<	*/
717	>	* The array of bins. Lazily initialized upon first insertion.
718	>	* Size is always a power of two. Accessed directly by iterators.
719	>	*/
720	>	transient volatile Node<K,V>[] table;
721
722	<	private static final long serialVersionUID = 2249069246763182397L;
722	>	/**
723	>	* The next table to use; non-null only while resizing.
724	>	*/
725	>	private transient volatile Node<K,V>[] nextTable;
726
727	<	/**
728	<	* The number of elements in this segment's region.
729	<	**/
730	<	transient volatile int count;
727	>	/**
728	>	* Base counter value, used mainly when there is no contention,
729	>	* but also as a fallback during table initialization
730	>	* races. Updated via CAS.
731	>	*/
732	>	private transient volatile long baseCount;
733
734	<	/**
735	<	* Number of updates that alter the size of the table. This is
736	<	* used during bulk-read methods to make sure they see a
737	<	* consistent snapshot: If modCounts change during a traversal
738	<	* of segments computing size or checking containsValue, then
739	<	* we might have an inconsistent view of state so (usually)
740	<	* must retry.
741	<	*/
742	<	transient int modCount;
734	>	/**
735	>	* Table initialization and resizing control.  When negative, the
736	>	* table is being initialized or resized: -1 for initialization,
737	>	* else -(1 + the number of active resizing threads).  Otherwise,
738	>	* when table is null, holds the initial table size to use upon
739	>	* creation, or 0 for default. After initialization, holds the
740	>	* next element count value upon which to resize the table.
741	>	*/
742	>	private transient volatile int sizeCtl;
743
744	<	/**
745	<	* The table is rehashed when its size exceeds this threshold.
746	<	* (The value of this field is always (int)(capacity *
747	<	* loadFactor).)
265	<	*/
266	<	transient int threshold;
744	>	/**
745	>	* The next table index (plus one) to split while resizing.
746	>	*/
747	>	private transient volatile int transferIndex;
748
749	<	/**
750	<	* The per-segment table. Declared as a raw type, casted
751	<	* to HashEntry<K,V> on each use.
752	<	*/
272	<	transient volatile HashEntry[] table;
749	>	/**
750	>	* The least available table index to split while resizing.
751	>	*/
752	>	private transient volatile int transferOrigin;
753
754	<	/**
755	<	* The load factor for the hash table.  Even though this value
756	<	* is same for all segments, it is replicated to avoid needing
757	<	* links to outer object.
278	<	* @serial
279	<	*/
280	<	final float loadFactor;
754	>	/**
755	>	* Spinlock (locked via CAS) used when resizing and/or creating CounterCells.
756	>	*/
757	>	private transient volatile int cellsBusy;
758
759	<	Segment(int initialCapacity, float lf) {
760	<	loadFactor = lf;
761	<	setTable(new HashEntry[initialCapacity]);
762	<	}
759	>	/**
760	>	* Table of counter cells. When non-null, size is a power of 2.
761	>	*/
762	>	private transient volatile CounterCell[] counterCells;
763
764	<	/**
765	<	* Set table to new HashEntry array.
766	<	* Call only while holding lock or in constructor.
767	<	**/
291	<	void setTable(HashEntry[] newTable) {
292	<	threshold = (int)(newTable.length * loadFactor);
293	<	table = newTable;
294	<	}
764	>	// views
765	>	private transient KeySetView<K,V> keySet;
766	>	private transient ValuesView<K,V> values;
767	>	private transient EntrySetView<K,V> entrySet;
768
769	<	/**
770	<	* Return properly casted first entry of bin for given hash
771	<	*/
772	<	HashEntry<K,V> getFirst(int hash) {
773	<	HashEntry[] tab = table;
774	<	return (HashEntry<K,V>) tab[hash & (tab.length - 1)];
769	>
770	>	/* ---------------- Public operations -------------- */
771	>
772	>	/**
773	>	* Creates a new, empty map with the default initial table size (16).
774	>	*/
775	>	public ConcurrentHashMap() {
776	>	}
777	>
778	>	/**
779	>	* Creates a new, empty map with an initial table size
780	>	* accommodating the specified number of elements without the need
781	>	* to dynamically resize.
782	>	*
783	>	* @param initialCapacity The implementation performs internal
784	>	* sizing to accommodate this many elements.
785	>	* @throws IllegalArgumentException if the initial capacity of
786	>	* elements is negative
787	>	*/
788	>	public ConcurrentHashMap(int initialCapacity) {
789	>	if (initialCapacity < 0)
790	>	throw new IllegalArgumentException();
791	>	int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
792	>	MAXIMUM_CAPACITY :
793	>	tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
794	>	this.sizeCtl = cap;
795	>	}
796	>
797	>	/**
798	>	* Creates a new map with the same mappings as the given map.
799	>	*
800	>	* @param m the map
801	>	*/
802	>	public ConcurrentHashMap(Map<? extends K, ? extends V> m) {
803	>	this.sizeCtl = DEFAULT_CAPACITY;
804	>	putAll(m);
805	>	}
806	>
807	>	/**
808	>	* Creates a new, empty map with an initial table size based on
809	>	* the given number of elements ({@code initialCapacity}) and
810	>	* initial table density ({@code loadFactor}).
811	>	*
812	>	* @param initialCapacity the initial capacity. The implementation
813	>	* performs internal sizing to accommodate this many elements,
814	>	* given the specified load factor.
815	>	* @param loadFactor the load factor (table density) for
816	>	* establishing the initial table size
817	>	* @throws IllegalArgumentException if the initial capacity of
818	>	* elements is negative or the load factor is nonpositive
819	>	*
820	>	* @since 1.6
821	>	*/
822	>	public ConcurrentHashMap(int initialCapacity, float loadFactor) {
823	>	this(initialCapacity, loadFactor, 1);
824	>	}
825	>
826	>	/**
827	>	* Creates a new, empty map with an initial table size based on
828	>	* the given number of elements ({@code initialCapacity}), table
829	>	* density ({@code loadFactor}), and number of concurrently
830	>	* updating threads ({@code concurrencyLevel}).
831	>	*
832	>	* @param initialCapacity the initial capacity. The implementation
833	>	* performs internal sizing to accommodate this many elements,
834	>	* given the specified load factor.
835	>	* @param loadFactor the load factor (table density) for
836	>	* establishing the initial table size
837	>	* @param concurrencyLevel the estimated number of concurrently
838	>	* updating threads. The implementation may use this value as
839	>	* a sizing hint.
840	>	* @throws IllegalArgumentException if the initial capacity is
841	>	* negative or the load factor or concurrencyLevel are
842	>	* nonpositive
843	>	*/
844	>	public ConcurrentHashMap(int initialCapacity,
845	>	float loadFactor, int concurrencyLevel) {
846	>	if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
847	>	throw new IllegalArgumentException();
848	>	if (initialCapacity < concurrencyLevel)   // Use at least as many bins
849	>	initialCapacity = concurrencyLevel;   // as estimated threads
850	>	long size = (long)(1.0 + (long)initialCapacity / loadFactor);
851	>	int cap = (size >= (long)MAXIMUM_CAPACITY) ?
852	>	MAXIMUM_CAPACITY : tableSizeFor((int)size);
853	>	this.sizeCtl = cap;
854	>	}
855	>
856	>	// Original (since JDK1.2) Map methods
857	>
858	>	/**
859	>	* {@inheritDoc}
860	>	*/
861	>	public int size() {
862	>	long n = sumCount();
863	>	return ((n < 0L) ? 0 :
864	>	(n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
865	>	(int)n);
866	>	}
867	>
868	>	/**
869	>	* {@inheritDoc}
870	>	*/
871	>	public boolean isEmpty() {
872	>	return sumCount() <= 0L; // ignore transient negative values
873	>	}
874	>
875	>	/**
876	>	* Returns the value to which the specified key is mapped,
877	>	* or {@code null} if this map contains no mapping for the key.
878	>	*
879	>	* <p>More formally, if this map contains a mapping from a key
880	>	* {@code k} to a value {@code v} such that {@code key.equals(k)},
881	>	* then this method returns {@code v}; otherwise it returns
882	>	* {@code null}.  (There can be at most one such mapping.)
883	>	*
884	>	* @throws NullPointerException if the specified key is null
885	>	*/
886	>	public V get(Object key) {
887	>	Node<K,V>[] tab; Node<K,V> e, p; int n, eh; K ek;
888	>	int h = spread(key.hashCode());
889	>	if ((tab = table) != null && (n = tab.length) > 0 &&
890	>	(e = tabAt(tab, (n - 1) & h)) != null) {
891	>	if ((eh = e.hash) == h) {
892	>	if ((ek = e.key) == key || (ek != null && key.equals(ek)))
893	>	return e.val;
894	>	}
895	>	else if (eh < 0)
896	>	return (p = e.find(h, key)) != null ? p.val : null;
897	>	while ((e = e.next) != null) {
898	>	if (e.hash == h &&
899	>	((ek = e.key) == key || (ek != null && key.equals(ek))))
900	>	return e.val;
901	>	}
902		}
903	+	return null;
904	+	}
905
906	<	/**
907	<	* Read value field of an entry under lock. Called if value
908	<	* field ever appears to be null. This is possible only if a
909	<	* compiler happens to reorder a HashEntry initialization with
910	<	* its table assignment, which is legal under memory model
911	<	* but is not known to ever occur.
912	<	*/
913	<	V readValueUnderLock(HashEntry<K,V> e) {
914	<	lock();
915	<	try {
916	<	return e.value;
917	<	} finally {
918	<	unlock();
906	>	/**
907	>	* Tests if the specified object is a key in this table.
908	>	*
909	>	* @param  key possible key
910	>	* @return {@code true} if and only if the specified object
911	>	*         is a key in this table, as determined by the
912	>	*         {@code equals} method; {@code false} otherwise
913	>	* @throws NullPointerException if the specified key is null
914	>	*/
915	>	public boolean containsKey(Object key) {
916	>	return get(key) != null;
917	>	}
918	>
919	>	/**
920	>	* Returns {@code true} if this map maps one or more keys to the
921	>	* specified value. Note: This method may require a full traversal
922	>	* of the map, and is much slower than method {@code containsKey}.
923	>	*
924	>	* @param value value whose presence in this map is to be tested
925	>	* @return {@code true} if this map maps one or more keys to the
926	>	*         specified value
927	>	* @throws NullPointerException if the specified value is null
928	>	*/
929	>	public boolean containsValue(Object value) {
930	>	if (value == null)
931	>	throw new NullPointerException();
932	>	Node<K,V>[] t;
933	>	if ((t = table) != null) {
934	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
935	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
936	>	V v;
937	>	if ((v = p.val) == value || (v != null && value.equals(v)))
938	>	return true;
939		}
940		}
941	+	return false;
942	+	}
943
944	<	/* Specialized implementations of map methods */
944	>	/**
945	>	* Maps the specified key to the specified value in this table.
946	>	* Neither the key nor the value can be null.
947	>	*
948	>	* <p>The value can be retrieved by calling the {@code get} method
949	>	* with a key that is equal to the original key.
950	>	*
951	>	* @param key key with which the specified value is to be associated
952	>	* @param value value to be associated with the specified key
953	>	* @return the previous value associated with {@code key}, or
954	>	*         {@code null} if there was no mapping for {@code key}
955	>	* @throws NullPointerException if the specified key or value is null
956	>	*/
957	>	public V put(K key, V value) {
958	>	return putVal(key, value, false);
959	>	}
960
961	<	V get(Object key, int hash) {
962	<	if (count != 0) { // read-volatile
963	<	HashEntry<K,V> e = getFirst(hash);
964	<	while (e != null) {
965	<	if (e.hash == hash && key.equals(e.key)) {
966	<	V v = e.value;
967	<	if (v != null)
968	<	return v;
969	<	return readValueUnderLock(e); // recheck
961	>	/** Implementation for put and putIfAbsent */
962	>	final V putVal(K key, V value, boolean onlyIfAbsent) {
963	>	if (key == null || value == null) throw new NullPointerException();
964	>	int hash = spread(key.hashCode());
965	>	int binCount = 0;
966	>	for (Node<K,V>[] tab = table;;) {
967	>	Node<K,V> f; int n, i, fh;
968	>	if (tab == null || (n = tab.length) == 0)
969	>	tab = initTable();
970	>	else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
971	>	if (casTabAt(tab, i, null,
972	>	new Node<K,V>(hash, key, value, null)))
973	>	break;                   // no lock when adding to empty bin
974	>	}
975	>	else if ((fh = f.hash) == MOVED)
976	>	tab = helpTransfer(tab, f);
977	>	else {
978	>	V oldVal = null;
979	>	synchronized (f) {
980	>	if (tabAt(tab, i) == f) {
981	>	if (fh >= 0) {
982	>	binCount = 1;
983	>	for (Node<K,V> e = f;; ++binCount) {
984	>	K ek;
985	>	if (e.hash == hash &&
986	>	((ek = e.key) == key ||
987	>	(ek != null && key.equals(ek)))) {
988	>	oldVal = e.val;
989	>	if (!onlyIfAbsent)
990	>	e.val = value;
991	>	break;
992	>	}
993	>	Node<K,V> pred = e;
994	>	if ((e = e.next) == null) {
995	>	pred.next = new Node<K,V>(hash, key,
996	>	value, null);
997	>	break;
998	>	}
999	>	}
1000	>	}
1001	>	else if (f instanceof TreeBin) {
1002	>	Node<K,V> p;
1003	>	binCount = 2;
1004	>	if ((p = ((TreeBin<K,V>)f).putTreeVal(hash, key,
1005	>	value)) != null) {
1006	>	oldVal = p.val;
1007	>	if (!onlyIfAbsent)
1008	>	p.val = value;
1009	>	}
1010	>	}
1011		}
1012	<	e = e.next;
1012	>	}
1013	>	if (binCount != 0) {
1014	>	if (binCount >= TREEIFY_THRESHOLD)
1015	>	treeifyBin(tab, i);
1016	>	if (oldVal != null)
1017	>	return oldVal;
1018	>	break;
1019		}
1020		}
335	–	return null;
1021		}
1022	+	addCount(1L, binCount);
1023	+	return null;
1024	+	}
1025
1026	<	boolean containsKey(Object key, int hash) {
1027	<	if (count != 0) { // read-volatile
1028	<	HashEntry<K,V> e = getFirst(hash);
1029	<	while (e != null) {
1030	<	if (e.hash == hash && key.equals(e.key))
1031	<	return true;
1032	<	e = e.next;
1026	>	/**
1027	>	* Copies all of the mappings from the specified map to this one.
1028	>	* These mappings replace any mappings that this map had for any of the
1029	>	* keys currently in the specified map.
1030	>	*
1031	>	* @param m mappings to be stored in this map
1032	>	*/
1033	>	public void putAll(Map<? extends K, ? extends V> m) {
1034	>	tryPresize(m.size());
1035	>	for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
1036	>	putVal(e.getKey(), e.getValue(), false);
1037	>	}
1038	>
1039	>	/**
1040	>	* Removes the key (and its corresponding value) from this map.
1041	>	* This method does nothing if the key is not in the map.
1042	>	*
1043	>	* @param  key the key that needs to be removed
1044	>	* @return the previous value associated with {@code key}, or
1045	>	*         {@code null} if there was no mapping for {@code key}
1046	>	* @throws NullPointerException if the specified key is null
1047	>	*/
1048	>	public V remove(Object key) {
1049	>	return replaceNode(key, null, null);
1050	>	}
1051	>
1052	>	/**
1053	>	* Implementation for the four public remove/replace methods:
1054	>	* Replaces node value with v, conditional upon match of cv if
1055	>	* non-null.  If resulting value is null, delete.
1056	>	*/
1057	>	final V replaceNode(Object key, V value, Object cv) {
1058	>	int hash = spread(key.hashCode());
1059	>	for (Node<K,V>[] tab = table;;) {
1060	>	Node<K,V> f; int n, i, fh;
1061	>	if (tab == null || (n = tab.length) == 0 ||
1062	>	(f = tabAt(tab, i = (n - 1) & hash)) == null)
1063	>	break;
1064	>	else if ((fh = f.hash) == MOVED)
1065	>	tab = helpTransfer(tab, f);
1066	>	else {
1067	>	V oldVal = null;
1068	>	boolean validated = false;
1069	>	synchronized (f) {
1070	>	if (tabAt(tab, i) == f) {
1071	>	if (fh >= 0) {
1072	>	validated = true;
1073	>	for (Node<K,V> e = f, pred = null;;) {
1074	>	K ek;
1075	>	if (e.hash == hash &&
1076	>	((ek = e.key) == key ||
1077	>	(ek != null && key.equals(ek)))) {
1078	>	V ev = e.val;
1079	>	if (cv == null || cv == ev ||
1080	>	(ev != null && cv.equals(ev))) {
1081	>	oldVal = ev;
1082	>	if (value != null)
1083	>	e.val = value;
1084	>	else if (pred != null)
1085	>	pred.next = e.next;
1086	>	else
1087	>	setTabAt(tab, i, e.next);
1088	>	}
1089	>	break;
1090	>	}
1091	>	pred = e;
1092	>	if ((e = e.next) == null)
1093	>	break;
1094	>	}
1095	>	}
1096	>	else if (f instanceof TreeBin) {
1097	>	validated = true;
1098	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1099	>	TreeNode<K,V> r, p;
1100	>	if ((r = t.root) != null &&
1101	>	(p = r.findTreeNode(hash, key, null)) != null) {
1102	>	V pv = p.val;
1103	>	if (cv == null || cv == pv ||
1104	>	(pv != null && cv.equals(pv))) {
1105	>	oldVal = pv;
1106	>	if (value != null)
1107	>	p.val = value;
1108	>	else if (t.removeTreeNode(p))
1109	>	setTabAt(tab, i, untreeify(t.first));
1110	>	}
1111	>	}
1112	>	}
1113	>	}
1114	>	}
1115	>	if (validated) {
1116	>	if (oldVal != null) {
1117	>	if (value == null)
1118	>	addCount(-1L, -1);
1119	>	return oldVal;
1120	>	}
1121	>	break;
1122		}
1123		}
347	–	return false;
1124		}
1125	+	return null;
1126	+	}
1127
1128	<	boolean containsValue(Object value) {
1129	<	if (count != 0) { // read-volatile
1130	<	HashEntry[] tab = table;
1131	<	int len = tab.length;
1132	<	for (int i = 0 ; i < len; i++) {
1133	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i];
1134	<	e != null ;
1135	<	e = e.next) {
1136	<	V v = e.value;
1137	<	if (v == null) // recheck
1138	<	v = readValueUnderLock(e);
1139	<	if (value.equals(v))
1140	<	return true;
1128	>	/**
1129	>	* Removes all of the mappings from this map.
1130	>	*/
1131	>	public void clear() {
1132	>	long delta = 0L; // negative number of deletions
1133	>	int i = 0;
1134	>	Node<K,V>[] tab = table;
1135	>	while (tab != null && i < tab.length) {
1136	>	int fh;
1137	>	Node<K,V> f = tabAt(tab, i);
1138	>	if (f == null)
1139	>	++i;
1140	>	else if ((fh = f.hash) == MOVED) {
1141	>	tab = helpTransfer(tab, f);
1142	>	i = 0; // restart
1143	>	}
1144	>	else {
1145	>	synchronized (f) {
1146	>	if (tabAt(tab, i) == f) {
1147	>	Node<K,V> p = (fh >= 0 ? f :
1148	>	(f instanceof TreeBin) ?
1149	>	((TreeBin<K,V>)f).first : null);
1150	>	while (p != null) {
1151	>	--delta;
1152	>	p = p.next;
1153	>	}
1154	>	setTabAt(tab, i++, null);
1155		}
1156		}
1157		}
366	–	return false;
1158		}
1159	+	if (delta != 0L)
1160	+	addCount(delta, -1);
1161	+	}
1162
1163	<	boolean replace(K key, int hash, V oldValue, V newValue) {
1164	<	lock();
1165	<	try {
1166	<	HashEntry<K,V> e = getFirst(hash);
1167	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1168	<	e = e.next;
1169	<
1170	<	boolean replaced = false;
1171	<	if (e != null && oldValue.equals(e.value)) {
1172	<	replaced = true;
1173	<	e.value = newValue;
1174	<	}
1175	<	return replaced;
1176	<	} finally {
1177	<	unlock();
1163	>	/**
1164	>	* Returns a {@link Set} view of the keys contained in this map.
1165	>	* The set is backed by the map, so changes to the map are
1166	>	* reflected in the set, and vice-versa. The set supports element
1167	>	* removal, which removes the corresponding mapping from this map,
1168	>	* via the {@code Iterator.remove}, {@code Set.remove},
1169	>	* {@code removeAll}, {@code retainAll}, and {@code clear}
1170	>	* operations.  It does not support the {@code add} or
1171	>	* {@code addAll} operations.
1172	>	*
1173	>	* <p>The view's iterators and spliterators are
1174	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1175	>	*
1176	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
1177	>	* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
1178	>	*
1179	>	* @return the set view
1180	>	*/
1181	>	public KeySetView<K,V> keySet() {
1182	>	KeySetView<K,V> ks;
1183	>	return (ks = keySet) != null ? ks : (keySet = new KeySetView<K,V>(this, null));
1184	>	}
1185	>
1186	>	/**
1187	>	* Returns a {@link Collection} view of the values contained in this map.
1188	>	* The collection is backed by the map, so changes to the map are
1189	>	* reflected in the collection, and vice-versa.  The collection
1190	>	* supports element removal, which removes the corresponding
1191	>	* mapping from this map, via the {@code Iterator.remove},
1192	>	* {@code Collection.remove}, {@code removeAll},
1193	>	* {@code retainAll}, and {@code clear} operations.  It does not
1194	>	* support the {@code add} or {@code addAll} operations.
1195	>	*
1196	>	* <p>The view's iterators and spliterators are
1197	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1198	>	*
1199	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT}
1200	>	* and {@link Spliterator#NONNULL}.
1201	>	*
1202	>	* @return the collection view
1203	>	*/
1204	>	public Collection<V> values() {
1205	>	ValuesView<K,V> vs;
1206	>	return (vs = values) != null ? vs : (values = new ValuesView<K,V>(this));
1207	>	}
1208	>
1209	>	/**
1210	>	* Returns a {@link Set} view of the mappings contained in this map.
1211	>	* The set is backed by the map, so changes to the map are
1212	>	* reflected in the set, and vice-versa.  The set supports element
1213	>	* removal, which removes the corresponding mapping from the map,
1214	>	* via the {@code Iterator.remove}, {@code Set.remove},
1215	>	* {@code removeAll}, {@code retainAll}, and {@code clear}
1216	>	* operations.
1217	>	*
1218	>	* <p>The view's iterators and spliterators are
1219	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1220	>	*
1221	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
1222	>	* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
1223	>	*
1224	>	* @return the set view
1225	>	*/
1226	>	public Set<Map.Entry<K,V>> entrySet() {
1227	>	EntrySetView<K,V> es;
1228	>	return (es = entrySet) != null ? es : (entrySet = new EntrySetView<K,V>(this));
1229	>	}
1230	>
1231	>	/**
1232	>	* Returns the hash code value for this {@link Map}, i.e.,
1233	>	* the sum of, for each key-value pair in the map,
1234	>	* {@code key.hashCode() ^ value.hashCode()}.
1235	>	*
1236	>	* @return the hash code value for this map
1237	>	*/
1238	>	public int hashCode() {
1239	>	int h = 0;
1240	>	Node<K,V>[] t;
1241	>	if ((t = table) != null) {
1242	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1243	>	for (Node<K,V> p; (p = it.advance()) != null; )
1244	>	h += p.key.hashCode() ^ p.val.hashCode();
1245	>	}
1246	>	return h;
1247	>	}
1248	>
1249	>	/**
1250	>	* Returns a string representation of this map.  The string
1251	>	* representation consists of a list of key-value mappings (in no
1252	>	* particular order) enclosed in braces ("{@code {}}").  Adjacent
1253	>	* mappings are separated by the characters {@code ", "} (comma
1254	>	* and space).  Each key-value mapping is rendered as the key
1255	>	* followed by an equals sign ("{@code =}") followed by the
1256	>	* associated value.
1257	>	*
1258	>	* @return a string representation of this map
1259	>	*/
1260	>	public String toString() {
1261	>	Node<K,V>[] t;
1262	>	int f = (t = table) == null ? 0 : t.length;
1263	>	Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1264	>	StringBuilder sb = new StringBuilder();
1265	>	sb.append('{');
1266	>	Node<K,V> p;
1267	>	if ((p = it.advance()) != null) {
1268	>	for (;;) {
1269	>	K k = p.key;
1270	>	V v = p.val;
1271	>	sb.append(k == this ? "(this Map)" : k);
1272	>	sb.append('=');
1273	>	sb.append(v == this ? "(this Map)" : v);
1274	>	if ((p = it.advance()) == null)
1275	>	break;
1276	>	sb.append(',').append(' ');
1277		}
1278		}
1279	+	return sb.append('}').toString();
1280	+	}
1281
1282	<	V replace(K key, int hash, V newValue) {
1283	<	lock();
1284	<	try {
1285	<	HashEntry<K,V> e = getFirst(hash);
1286	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1287	<	e = e.next;
1288	<
1289	<	V oldValue = null;
1290	<	if (e != null) {
1291	<	oldValue = e.value;
1292	<	e.value = newValue;
1293	<	}
1294	<	return oldValue;
1295	<	} finally {
1296	<	unlock();
1282	>	/**
1283	>	* Compares the specified object with this map for equality.
1284	>	* Returns {@code true} if the given object is a map with the same
1285	>	* mappings as this map.  This operation may return misleading
1286	>	* results if either map is concurrently modified during execution
1287	>	* of this method.
1288	>	*
1289	>	* @param o object to be compared for equality with this map
1290	>	* @return {@code true} if the specified object is equal to this map
1291	>	*/
1292	>	public boolean equals(Object o) {
1293	>	if (o != this) {
1294	>	if (!(o instanceof Map))
1295	>	return false;
1296	>	Map<?,?> m = (Map<?,?>) o;
1297	>	Node<K,V>[] t;
1298	>	int f = (t = table) == null ? 0 : t.length;
1299	>	Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1300	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1301	>	V val = p.val;
1302	>	Object v = m.get(p.key);
1303	>	if (v == null || (v != val && !v.equals(val)))
1304	>	return false;
1305	>	}
1306	>	for (Map.Entry<?,?> e : m.entrySet()) {
1307	>	Object mk, mv, v;
1308	>	if ((mk = e.getKey()) == null ||
1309	>	(mv = e.getValue()) == null ||
1310	>	(v = get(mk)) == null ||
1311	>	(mv != v && !mv.equals(v)))
1312	>	return false;
1313		}
1314		}
1315	+	return true;
1316	+	}
1317
1318	+	/**
1319	+	* Stripped-down version of helper class used in previous version,
1320	+	* declared for the sake of serialization compatibility
1321	+	*/
1322	+	static class Segment<K,V> extends ReentrantLock implements Serializable {
1323	+	private static final long serialVersionUID = 2249069246763182397L;
1324	+	final float loadFactor;
1325	+	Segment(float lf) { this.loadFactor = lf; }
1326	+	}
1327
1328	<	V put(K key, int hash, V value, boolean onlyIfAbsent) {
1329	<	lock();
1330	<	try {
1331	<	int c = count;
1332	<	if (c++ > threshold) // ensure capacity
1333	<	rehash();
1334	<	HashEntry[] tab = table;
1335	<	int index = hash & (tab.length - 1);
1336	<	HashEntry<K,V> first = (HashEntry<K,V>) tab[index];
1337	<	HashEntry<K,V> e = first;
1338	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1339	<	e = e.next;
1340	<
1341	<	V oldValue;
1342	<	if (e != null) {
1343	<	oldValue = e.value;
1344	<	if (!onlyIfAbsent)
1345	<	e.value = value;
1346	<	}
1328	>	/**
1329	>	* Saves the state of the {@code ConcurrentHashMap} instance to a
1330	>	* stream (i.e., serializes it).
1331	>	* @param s the stream
1332	>	* @throws java.io.IOException if an I/O error occurs
1333	>	* @serialData
1334	>	* the key (Object) and value (Object)
1335	>	* for each key-value mapping, followed by a null pair.
1336	>	* The key-value mappings are emitted in no particular order.
1337	>	*/
1338	>	private void writeObject(java.io.ObjectOutputStream s)
1339	>	throws java.io.IOException {
1340	>	// For serialization compatibility
1341	>	// Emulate segment calculation from previous version of this class
1342	>	int sshift = 0;
1343	>	int ssize = 1;
1344	>	while (ssize < DEFAULT_CONCURRENCY_LEVEL) {
1345	>	++sshift;
1346	>	ssize <<= 1;
1347	>	}
1348	>	int segmentShift = 32 - sshift;
1349	>	int segmentMask = ssize - 1;
1350	>	@SuppressWarnings("unchecked") Segment<K,V>[] segments = (Segment<K,V>[])
1351	>	new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
1352	>	for (int i = 0; i < segments.length; ++i)
1353	>	segments[i] = new Segment<K,V>(LOAD_FACTOR);
1354	>	s.putFields().put("segments", segments);
1355	>	s.putFields().put("segmentShift", segmentShift);
1356	>	s.putFields().put("segmentMask", segmentMask);
1357	>	s.writeFields();
1358	>
1359	>	Node<K,V>[] t;
1360	>	if ((t = table) != null) {
1361	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1362	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1363	>	s.writeObject(p.key);
1364	>	s.writeObject(p.val);
1365	>	}
1366	>	}
1367	>	s.writeObject(null);
1368	>	s.writeObject(null);
1369	>	segments = null; // throw away
1370	>	}
1371	>
1372	>	/**
1373	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1374	>	* @param s the stream
1375	>	* @throws ClassNotFoundException if the class of a serialized object
1376	>	*         could not be found
1377	>	* @throws java.io.IOException if an I/O error occurs
1378	>	*/
1379	>	private void readObject(java.io.ObjectInputStream s)
1380	>	throws java.io.IOException, ClassNotFoundException {
1381	>	/*
1382	>	* To improve performance in typical cases, we create nodes
1383	>	* while reading, then place in table once size is known.
1384	>	* However, we must also validate uniqueness and deal with
1385	>	* overpopulated bins while doing so, which requires
1386	>	* specialized versions of putVal mechanics.
1387	>	*/
1388	>	sizeCtl = -1; // force exclusion for table construction
1389	>	s.defaultReadObject();
1390	>	long size = 0L;
1391	>	Node<K,V> p = null;
1392	>	for (;;) {
1393	>	@SuppressWarnings("unchecked") K k = (K) s.readObject();
1394	>	@SuppressWarnings("unchecked") V v = (V) s.readObject();
1395	>	if (k != null && v != null) {
1396	>	p = new Node<K,V>(spread(k.hashCode()), k, v, p);
1397	>	++size;
1398	>	}
1399	>	else
1400	>	break;
1401	>	}
1402	>	if (size == 0L)
1403	>	sizeCtl = 0;
1404	>	else {
1405	>	int n;
1406	>	if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
1407	>	n = MAXIMUM_CAPACITY;
1408	>	else {
1409	>	int sz = (int)size;
1410	>	n = tableSizeFor(sz + (sz >>> 1) + 1);
1411	>	}
1412	>	@SuppressWarnings({"rawtypes","unchecked"})
1413	>	Node<K,V>[] tab = (Node<K,V>[])new Node[n];
1414	>	int mask = n - 1;
1415	>	long added = 0L;
1416	>	while (p != null) {
1417	>	boolean insertAtFront;
1418	>	Node<K,V> next = p.next, first;
1419	>	int h = p.hash, j = h & mask;
1420	>	if ((first = tabAt(tab, j)) == null)
1421	>	insertAtFront = true;
1422		else {
1423	<	oldValue = null;
1424	<	++modCount;
1425	<	tab[index] = new HashEntry<K,V>(key, hash, first, value);
1426	<	count = c; // write-volatile
1423	>	K k = p.key;
1424	>	if (first.hash < 0) {
1425	>	TreeBin<K,V> t = (TreeBin<K,V>)first;
1426	>	if (t.putTreeVal(h, k, p.val) == null)
1427	>	++added;
1428	>	insertAtFront = false;
1429	>	}
1430	>	else {
1431	>	int binCount = 0;
1432	>	insertAtFront = true;
1433	>	Node<K,V> q; K qk;
1434	>	for (q = first; q != null; q = q.next) {
1435	>	if (q.hash == h &&
1436	>	((qk = q.key) == k ||
1437	>	(qk != null && k.equals(qk)))) {
1438	>	insertAtFront = false;
1439	>	break;
1440	>	}
1441	>	++binCount;
1442	>	}
1443	>	if (insertAtFront && binCount >= TREEIFY_THRESHOLD) {
1444	>	insertAtFront = false;
1445	>	++added;
1446	>	p.next = first;
1447	>	TreeNode<K,V> hd = null, tl = null;
1448	>	for (q = p; q != null; q = q.next) {
1449	>	TreeNode<K,V> t = new TreeNode<K,V>
1450	>	(q.hash, q.key, q.val, null, null);
1451	>	if ((t.prev = tl) == null)
1452	>	hd = t;
1453	>	else
1454	>	tl.next = t;
1455	>	tl = t;
1456	>	}
1457	>	setTabAt(tab, j, new TreeBin<K,V>(hd));
1458	>	}
1459	>	}
1460		}
1461	<	return oldValue;
1462	<	} finally {
1463	<	unlock();
1461	>	if (insertAtFront) {
1462	>	++added;
1463	>	p.next = first;
1464	>	setTabAt(tab, j, p);
1465	>	}
1466	>	p = next;
1467		}
1468	+	table = tab;
1469	+	sizeCtl = n - (n >>> 2);
1470	+	baseCount = added;
1471		}
1472	+	}
1473
1474	<	void rehash() {
438	<	HashEntry[] oldTable = table;
439	<	int oldCapacity = oldTable.length;
440	<	if (oldCapacity >= MAXIMUM_CAPACITY)
441	<	return;
1474	>	// ConcurrentMap methods
1475
1476	<	/*
1477	<	* Reclassify nodes in each list to new Map.  Because we are
1478	<	* using power-of-two expansion, the elements from each bin
1479	<	* must either stay at same index, or move with a power of two
1480	<	* offset. We eliminate unnecessary node creation by catching
1481	<	* cases where old nodes can be reused because their next
1482	<	* fields won't change. Statistically, at the default
1483	<	* threshold, only about one-sixth of them need cloning when
1484	<	* a table doubles. The nodes they replace will be garbage
1485	<	* collectable as soon as they are no longer referenced by any
453	<	* reader thread that may be in the midst of traversing table
454	<	* right now.
455	<	*/
456	<
457	<	HashEntry[] newTable = new HashEntry[oldCapacity << 1];
458	<	threshold = (int)(newTable.length * loadFactor);
459	<	int sizeMask = newTable.length - 1;
460	<	for (int i = 0; i < oldCapacity ; i++) {
461	<	// We need to guarantee that any existing reads of old Map can
462	<	//  proceed. So we cannot yet null out each bin.
463	<	HashEntry<K,V> e = (HashEntry<K,V>)oldTable[i];
464	<
465	<	if (e != null) {
466	<	HashEntry<K,V> next = e.next;
467	<	int idx = e.hash & sizeMask;
468	<
469	<	//  Single node on list
470	<	if (next == null)
471	<	newTable[idx] = e;
1476	>	/**
1477	>	* {@inheritDoc}
1478	>	*
1479	>	* @return the previous value associated with the specified key,
1480	>	*         or {@code null} if there was no mapping for the key
1481	>	* @throws NullPointerException if the specified key or value is null
1482	>	*/
1483	>	public V putIfAbsent(K key, V value) {
1484	>	return putVal(key, value, true);
1485	>	}
1486
1487	<	else {
1488	<	// Reuse trailing consecutive sequence at same slot
1489	<	HashEntry<K,V> lastRun = e;
1490	<	int lastIdx = idx;
1491	<	for (HashEntry<K,V> last = next;
1492	<	last != null;
1493	<	last = last.next) {
1494	<	int k = last.hash & sizeMask;
1495	<	if (k != lastIdx) {
1496	<	lastIdx = k;
1497	<	lastRun = last;
1487	>	/**
1488	>	* {@inheritDoc}
1489	>	*
1490	>	* @throws NullPointerException if the specified key is null
1491	>	*/
1492	>	public boolean remove(Object key, Object value) {
1493	>	if (key == null)
1494	>	throw new NullPointerException();
1495	>	return value != null && replaceNode(key, null, value) != null;
1496	>	}
1497	>
1498	>	/**
1499	>	* {@inheritDoc}
1500	>	*
1501	>	* @throws NullPointerException if any of the arguments are null
1502	>	*/
1503	>	public boolean replace(K key, V oldValue, V newValue) {
1504	>	if (key == null || oldValue == null || newValue == null)
1505	>	throw new NullPointerException();
1506	>	return replaceNode(key, newValue, oldValue) != null;
1507	>	}
1508	>
1509	>	/**
1510	>	* {@inheritDoc}
1511	>	*
1512	>	* @return the previous value associated with the specified key,
1513	>	*         or {@code null} if there was no mapping for the key
1514	>	* @throws NullPointerException if the specified key or value is null
1515	>	*/
1516	>	public V replace(K key, V value) {
1517	>	if (key == null || value == null)
1518	>	throw new NullPointerException();
1519	>	return replaceNode(key, value, null);
1520	>	}
1521	>
1522	>	// Overrides of JDK8+ Map extension method defaults
1523	>
1524	>	/**
1525	>	* Returns the value to which the specified key is mapped, or the
1526	>	* given default value if this map contains no mapping for the
1527	>	* key.
1528	>	*
1529	>	* @param key the key whose associated value is to be returned
1530	>	* @param defaultValue the value to return if this map contains
1531	>	* no mapping for the given key
1532	>	* @return the mapping for the key, if present; else the default value
1533	>	* @throws NullPointerException if the specified key is null
1534	>	*/
1535	>	public V getOrDefault(Object key, V defaultValue) {
1536	>	V v;
1537	>	return (v = get(key)) == null ? defaultValue : v;
1538	>	}
1539	>
1540	>	public void forEach(BiConsumer<? super K, ? super V> action) {
1541	>	if (action == null) throw new NullPointerException();
1542	>	Node<K,V>[] t;
1543	>	if ((t = table) != null) {
1544	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1545	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1546	>	action.accept(p.key, p.val);
1547	>	}
1548	>	}
1549	>	}
1550	>
1551	>	public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1552	>	if (function == null) throw new NullPointerException();
1553	>	Node<K,V>[] t;
1554	>	if ((t = table) != null) {
1555	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1556	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1557	>	V oldValue = p.val;
1558	>	for (K key = p.key;;) {
1559	>	V newValue = function.apply(key, oldValue);
1560	>	if (newValue == null)
1561	>	throw new NullPointerException();
1562	>	if (replaceNode(key, newValue, oldValue) != null ||
1563	>	(oldValue = get(key)) == null)
1564	>	break;
1565	>	}
1566	>	}
1567	>	}
1568	>	}
1569	>
1570	>	/**
1571	>	* If the specified key is not already associated with a value,
1572	>	* attempts to compute its value using the given mapping function
1573	>	* and enters it into this map unless {@code null}.  The entire
1574	>	* method invocation is performed atomically, so the function is
1575	>	* applied at most once per key.  Some attempted update operations
1576	>	* on this map by other threads may be blocked while computation
1577	>	* is in progress, so the computation should be short and simple,
1578	>	* and must not attempt to update any other mappings of this map.
1579	>	*
1580	>	* @param key key with which the specified value is to be associated
1581	>	* @param mappingFunction the function to compute a value
1582	>	* @return the current (existing or computed) value associated with
1583	>	*         the specified key, or null if the computed value is null
1584	>	* @throws NullPointerException if the specified key or mappingFunction
1585	>	*         is null
1586	>	* @throws IllegalStateException if the computation detectably
1587	>	*         attempts a recursive update to this map that would
1588	>	*         otherwise never complete
1589	>	* @throws RuntimeException or Error if the mappingFunction does so,
1590	>	*         in which case the mapping is left unestablished
1591	>	*/
1592	>	public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
1593	>	if (key == null || mappingFunction == null)
1594	>	throw new NullPointerException();
1595	>	int h = spread(key.hashCode());
1596	>	V val = null;
1597	>	int binCount = 0;
1598	>	for (Node<K,V>[] tab = table;;) {
1599	>	Node<K,V> f; int n, i, fh;
1600	>	if (tab == null || (n = tab.length) == 0)
1601	>	tab = initTable();
1602	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1603	>	Node<K,V> r = new ReservationNode<K,V>();
1604	>	synchronized (r) {
1605	>	if (casTabAt(tab, i, null, r)) {
1606	>	binCount = 1;
1607	>	Node<K,V> node = null;
1608	>	try {
1609	>	if ((val = mappingFunction.apply(key)) != null)
1610	>	node = new Node<K,V>(h, key, val, null);
1611	>	} finally {
1612	>	setTabAt(tab, i, node);
1613	>	}
1614	>	}
1615	>	}
1616	>	if (binCount != 0)
1617	>	break;
1618	>	}
1619	>	else if ((fh = f.hash) == MOVED)
1620	>	tab = helpTransfer(tab, f);
1621	>	else {
1622	>	boolean added = false;
1623	>	synchronized (f) {
1624	>	if (tabAt(tab, i) == f) {
1625	>	if (fh >= 0) {
1626	>	binCount = 1;
1627	>	for (Node<K,V> e = f;; ++binCount) {
1628	>	K ek; V ev;
1629	>	if (e.hash == h &&
1630	>	((ek = e.key) == key ||
1631	>	(ek != null && key.equals(ek)))) {
1632	>	val = e.val;
1633	>	break;
1634	>	}
1635	>	Node<K,V> pred = e;
1636	>	if ((e = e.next) == null) {
1637	>	if ((val = mappingFunction.apply(key)) != null) {
1638	>	added = true;
1639	>	pred.next = new Node<K,V>(h, key, val, null);
1640	>	}
1641	>	break;
1642	>	}
1643		}
1644		}
1645	<	newTable[lastIdx] = lastRun;
1645	>	else if (f instanceof TreeBin) {
1646	>	binCount = 2;
1647	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1648	>	TreeNode<K,V> r, p;
1649	>	if ((r = t.root) != null &&
1650	>	(p = r.findTreeNode(h, key, null)) != null)
1651	>	val = p.val;
1652	>	else if ((val = mappingFunction.apply(key)) != null) {
1653	>	added = true;
1654	>	t.putTreeVal(h, key, val);
1655	>	}
1656	>	}
1657	>	}
1658	>	}
1659	>	if (binCount != 0) {
1660	>	if (binCount >= TREEIFY_THRESHOLD)
1661	>	treeifyBin(tab, i);
1662	>	if (!added)
1663	>	return val;
1664	>	break;
1665	>	}
1666	>	}
1667	>	}
1668	>	if (val != null)
1669	>	addCount(1L, binCount);
1670	>	return val;
1671	>	}
1672
1673	<	// Clone all remaining nodes
1674	<	for (HashEntry<K,V> p = e; p != lastRun; p = p.next) {
1675	<	int k = p.hash & sizeMask;
1676	<	HashEntry<K,V> n = (HashEntry<K,V>)newTable[k];
1677	<	newTable[k] = new HashEntry<K,V>(p.key, p.hash,
1678	<	n, p.value);
1673	>	/**
1674	>	* If the value for the specified key is present, attempts to
1675	>	* compute a new mapping given the key and its current mapped
1676	>	* value.  The entire method invocation is performed atomically.
1677	>	* Some attempted update operations on this map by other threads
1678	>	* may be blocked while computation is in progress, so the
1679	>	* computation should be short and simple, and must not attempt to
1680	>	* update any other mappings of this map.
1681	>	*
1682	>	* @param key key with which a value may be associated
1683	>	* @param remappingFunction the function to compute a value
1684	>	* @return the new value associated with the specified key, or null if none
1685	>	* @throws NullPointerException if the specified key or remappingFunction
1686	>	*         is null
1687	>	* @throws IllegalStateException if the computation detectably
1688	>	*         attempts a recursive update to this map that would
1689	>	*         otherwise never complete
1690	>	* @throws RuntimeException or Error if the remappingFunction does so,
1691	>	*         in which case the mapping is unchanged
1692	>	*/
1693	>	public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1694	>	if (key == null || remappingFunction == null)
1695	>	throw new NullPointerException();
1696	>	int h = spread(key.hashCode());
1697	>	V val = null;
1698	>	int delta = 0;
1699	>	int binCount = 0;
1700	>	for (Node<K,V>[] tab = table;;) {
1701	>	Node<K,V> f; int n, i, fh;
1702	>	if (tab == null || (n = tab.length) == 0)
1703	>	tab = initTable();
1704	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null)
1705	>	break;
1706	>	else if ((fh = f.hash) == MOVED)
1707	>	tab = helpTransfer(tab, f);
1708	>	else {
1709	>	synchronized (f) {
1710	>	if (tabAt(tab, i) == f) {
1711	>	if (fh >= 0) {
1712	>	binCount = 1;
1713	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1714	>	K ek;
1715	>	if (e.hash == h &&
1716	>	((ek = e.key) == key ||
1717	>	(ek != null && key.equals(ek)))) {
1718	>	val = remappingFunction.apply(key, e.val);
1719	>	if (val != null)
1720	>	e.val = val;
1721	>	else {
1722	>	delta = -1;
1723	>	Node<K,V> en = e.next;
1724	>	if (pred != null)
1725	>	pred.next = en;
1726	>	else
1727	>	setTabAt(tab, i, en);
1728	>	}
1729	>	break;
1730	>	}
1731	>	pred = e;
1732	>	if ((e = e.next) == null)
1733	>	break;
1734	>	}
1735	>	}
1736	>	else if (f instanceof TreeBin) {
1737	>	binCount = 2;
1738	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1739	>	TreeNode<K,V> r, p;
1740	>	if ((r = t.root) != null &&
1741	>	(p = r.findTreeNode(h, key, null)) != null) {
1742	>	val = remappingFunction.apply(key, p.val);
1743	>	if (val != null)
1744	>	p.val = val;
1745	>	else {
1746	>	delta = -1;
1747	>	if (t.removeTreeNode(p))
1748	>	setTabAt(tab, i, untreeify(t.first));
1749	>	}
1750	>	}
1751		}
1752		}
1753		}
1754	+	if (binCount != 0)
1755	+	break;
1756		}
498	–	table = newTable;
1757		}
1758	+	if (delta != 0)
1759	+	addCount((long)delta, binCount);
1760	+	return val;
1761	+	}
1762
1763	<	/**
1764	<	* Remove; match on key only if value null, else match both.
1765	<	*/
1766	<	V remove(Object key, int hash, Object value) {
1767	<	lock();
1768	<	try {
1769	<	int c = count - 1;
1770	<	HashEntry[] tab = table;
1771	<	int index = hash & (tab.length - 1);
1772	<	HashEntry<K,V> first = (HashEntry<K,V>)tab[index];
1773	<	HashEntry<K,V> e = first;
1774	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1775	<	e = e.next;
1776	<
1777	<	V oldValue = null;
1778	<	if (e != null) {
1779	<	V v = e.value;
1780	<	if (value == null || value.equals(v)) {
1781	<	oldValue = v;
1782	<	// All entries following removed node can stay
1783	<	// in list, but all preceding ones need to be
1784	<	// cloned.
1785	<	++modCount;
1786	<	HashEntry<K,V> newFirst = e.next;
1787	<	for (HashEntry<K,V> p = first; p != e; p = p.next)
1788	<	newFirst = new HashEntry<K,V>(p.key, p.hash,
1789	<	newFirst, p.value);
1790	<	tab[index] = newFirst;
1791	<	count = c; // write-volatile
1763	>	/**
1764	>	* Attempts to compute a mapping for the specified key and its
1765	>	* current mapped value (or {@code null} if there is no current
1766	>	* mapping). The entire method invocation is performed atomically.
1767	>	* Some attempted update operations on this map by other threads
1768	>	* may be blocked while computation is in progress, so the
1769	>	* computation should be short and simple, and must not attempt to
1770	>	* update any other mappings of this Map.
1771	>	*
1772	>	* @param key key with which the specified value is to be associated
1773	>	* @param remappingFunction the function to compute a value
1774	>	* @return the new value associated with the specified key, or null if none
1775	>	* @throws NullPointerException if the specified key or remappingFunction
1776	>	*         is null
1777	>	* @throws IllegalStateException if the computation detectably
1778	>	*         attempts a recursive update to this map that would
1779	>	*         otherwise never complete
1780	>	* @throws RuntimeException or Error if the remappingFunction does so,
1781	>	*         in which case the mapping is unchanged
1782	>	*/
1783	>	public V compute(K key,
1784	>	BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1785	>	if (key == null || remappingFunction == null)
1786	>	throw new NullPointerException();
1787	>	int h = spread(key.hashCode());
1788	>	V val = null;
1789	>	int delta = 0;
1790	>	int binCount = 0;
1791	>	for (Node<K,V>[] tab = table;;) {
1792	>	Node<K,V> f; int n, i, fh;
1793	>	if (tab == null || (n = tab.length) == 0)
1794	>	tab = initTable();
1795	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1796	>	Node<K,V> r = new ReservationNode<K,V>();
1797	>	synchronized (r) {
1798	>	if (casTabAt(tab, i, null, r)) {
1799	>	binCount = 1;
1800	>	Node<K,V> node = null;
1801	>	try {
1802	>	if ((val = remappingFunction.apply(key, null)) != null) {
1803	>	delta = 1;
1804	>	node = new Node<K,V>(h, key, val, null);
1805	>	}
1806	>	} finally {
1807	>	setTabAt(tab, i, node);
1808	>	}
1809		}
1810		}
1811	<	return oldValue;
1812	<	} finally {
1813	<	unlock();
1811	>	if (binCount != 0)
1812	>	break;
1813	>	}
1814	>	else if ((fh = f.hash) == MOVED)
1815	>	tab = helpTransfer(tab, f);
1816	>	else {
1817	>	synchronized (f) {
1818	>	if (tabAt(tab, i) == f) {
1819	>	if (fh >= 0) {
1820	>	binCount = 1;
1821	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1822	>	K ek;
1823	>	if (e.hash == h &&
1824	>	((ek = e.key) == key ||
1825	>	(ek != null && key.equals(ek)))) {
1826	>	val = remappingFunction.apply(key, e.val);
1827	>	if (val != null)
1828	>	e.val = val;
1829	>	else {
1830	>	delta = -1;
1831	>	Node<K,V> en = e.next;
1832	>	if (pred != null)
1833	>	pred.next = en;
1834	>	else
1835	>	setTabAt(tab, i, en);
1836	>	}
1837	>	break;
1838	>	}
1839	>	pred = e;
1840	>	if ((e = e.next) == null) {
1841	>	val = remappingFunction.apply(key, null);
1842	>	if (val != null) {
1843	>	delta = 1;
1844	>	pred.next =
1845	>	new Node<K,V>(h, key, val, null);
1846	>	}
1847	>	break;
1848	>	}
1849	>	}
1850	>	}
1851	>	else if (f instanceof TreeBin) {
1852	>	binCount = 1;
1853	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1854	>	TreeNode<K,V> r, p;
1855	>	if ((r = t.root) != null)
1856	>	p = r.findTreeNode(h, key, null);
1857	>	else
1858	>	p = null;
1859	>	V pv = (p == null) ? null : p.val;
1860	>	val = remappingFunction.apply(key, pv);
1861	>	if (val != null) {
1862	>	if (p != null)
1863	>	p.val = val;
1864	>	else {
1865	>	delta = 1;
1866	>	t.putTreeVal(h, key, val);
1867	>	}
1868	>	}
1869	>	else if (p != null) {
1870	>	delta = -1;
1871	>	if (t.removeTreeNode(p))
1872	>	setTabAt(tab, i, untreeify(t.first));
1873	>	}
1874	>	}
1875	>	}
1876	>	}
1877	>	if (binCount != 0) {
1878	>	if (binCount >= TREEIFY_THRESHOLD)
1879	>	treeifyBin(tab, i);
1880	>	break;
1881	>	}
1882		}
1883		}
1884	+	if (delta != 0)
1885	+	addCount((long)delta, binCount);
1886	+	return val;
1887	+	}
1888
1889	<	void clear() {
1890	<	if (count != 0) {
1891	<	lock();
1892	<	try {
1893	<	HashEntry[] tab = table;
1894	<	for (int i = 0; i < tab.length ; i++)
1895	<	tab[i] = null;
1896	<	++modCount;
1897	<	count = 0; // write-volatile
1898	<	} finally {
1899	<	unlock();
1889	>	/**
1890	>	* If the specified key is not already associated with a
1891	>	* (non-null) value, associates it with the given value.
1892	>	* Otherwise, replaces the value with the results of the given
1893	>	* remapping function, or removes if {@code null}. The entire
1894	>	* method invocation is performed atomically.  Some attempted
1895	>	* update operations on this map by other threads may be blocked
1896	>	* while computation is in progress, so the computation should be
1897	>	* short and simple, and must not attempt to update any other
1898	>	* mappings of this Map.
1899	>	*
1900	>	* @param key key with which the specified value is to be associated
1901	>	* @param value the value to use if absent
1902	>	* @param remappingFunction the function to recompute a value if present
1903	>	* @return the new value associated with the specified key, or null if none
1904	>	* @throws NullPointerException if the specified key or the
1905	>	*         remappingFunction is null
1906	>	* @throws RuntimeException or Error if the remappingFunction does so,
1907	>	*         in which case the mapping is unchanged
1908	>	*/
1909	>	public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1910	>	if (key == null || value == null || remappingFunction == null)
1911	>	throw new NullPointerException();
1912	>	int h = spread(key.hashCode());
1913	>	V val = null;
1914	>	int delta = 0;
1915	>	int binCount = 0;
1916	>	for (Node<K,V>[] tab = table;;) {
1917	>	Node<K,V> f; int n, i, fh;
1918	>	if (tab == null || (n = tab.length) == 0)
1919	>	tab = initTable();
1920	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1921	>	if (casTabAt(tab, i, null, new Node<K,V>(h, key, value, null))) {
1922	>	delta = 1;
1923	>	val = value;
1924	>	break;
1925	>	}
1926	>	}
1927	>	else if ((fh = f.hash) == MOVED)
1928	>	tab = helpTransfer(tab, f);
1929	>	else {
1930	>	synchronized (f) {
1931	>	if (tabAt(tab, i) == f) {
1932	>	if (fh >= 0) {
1933	>	binCount = 1;
1934	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1935	>	K ek;
1936	>	if (e.hash == h &&
1937	>	((ek = e.key) == key ||
1938	>	(ek != null && key.equals(ek)))) {
1939	>	val = remappingFunction.apply(e.val, value);
1940	>	if (val != null)
1941	>	e.val = val;
1942	>	else {
1943	>	delta = -1;
1944	>	Node<K,V> en = e.next;
1945	>	if (pred != null)
1946	>	pred.next = en;
1947	>	else
1948	>	setTabAt(tab, i, en);
1949	>	}
1950	>	break;
1951	>	}
1952	>	pred = e;
1953	>	if ((e = e.next) == null) {
1954	>	delta = 1;
1955	>	val = value;
1956	>	pred.next =
1957	>	new Node<K,V>(h, key, val, null);
1958	>	break;
1959	>	}
1960	>	}
1961	>	}
1962	>	else if (f instanceof TreeBin) {
1963	>	binCount = 2;
1964	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1965	>	TreeNode<K,V> r = t.root;
1966	>	TreeNode<K,V> p = (r == null) ? null :
1967	>	r.findTreeNode(h, key, null);
1968	>	val = (p == null) ? value :
1969	>	remappingFunction.apply(p.val, value);
1970	>	if (val != null) {
1971	>	if (p != null)
1972	>	p.val = val;
1973	>	else {
1974	>	delta = 1;
1975	>	t.putTreeVal(h, key, val);
1976	>	}
1977	>	}
1978	>	else if (p != null) {
1979	>	delta = -1;
1980	>	if (t.removeTreeNode(p))
1981	>	setTabAt(tab, i, untreeify(t.first));
1982	>	}
1983	>	}
1984	>	}
1985	>	}
1986	>	if (binCount != 0) {
1987	>	if (binCount >= TREEIFY_THRESHOLD)
1988	>	treeifyBin(tab, i);
1989	>	break;
1990		}
1991		}
1992		}
1993	+	if (delta != 0)
1994	+	addCount((long)delta, binCount);
1995	+	return val;
1996		}
1997
1998	+	// Hashtable legacy methods
1999
2000	+	/**
2001	+	* Legacy method testing if some key maps into the specified value
2002	+	* in this table.  This method is identical in functionality to
2003	+	* {@link #containsValue(Object)}, and exists solely to ensure
2004	+	* full compatibility with class {@link java.util.Hashtable},
2005	+	* which supported this method prior to introduction of the
2006	+	* Java Collections framework.
2007	+	*
2008	+	* @param  value a value to search for
2009	+	* @return {@code true} if and only if some key maps to the
2010	+	*         {@code value} argument in this table as
2011	+	*         determined by the {@code equals} method;
2012	+	*         {@code false} otherwise
2013	+	* @throws NullPointerException if the specified value is null
2014	+	*/
2015	+	@Deprecated public boolean contains(Object value) {
2016	+	return containsValue(value);
2017	+	}
2018
2019	<	/* ---------------- Public operations -------------- */
2019	>	/**
2020	>	* Returns an enumeration of the keys in this table.
2021	>	*
2022	>	* @return an enumeration of the keys in this table
2023	>	* @see #keySet()
2024	>	*/
2025	>	public Enumeration<K> keys() {
2026	>	Node<K,V>[] t;
2027	>	int f = (t = table) == null ? 0 : t.length;
2028	>	return new KeyIterator<K,V>(t, f, 0, f, this);
2029	>	}
2030
2031		/**
2032	<	* Creates a new, empty map with the specified initial
560	<	* capacity, load factor, and concurrency level.
2032	>	* Returns an enumeration of the values in this table.
2033		*
2034	<	* @param initialCapacity the initial capacity. The implementation
2035	<	* performs internal sizing to accommodate this many elements.
564	<	* @param loadFactor  the load factor threshold, used to control resizing.
565	<	* Resizing may be performed when the average number of elements per
566	<	* bin exceeds this threshold.
567	<	* @param concurrencyLevel the estimated number of concurrently
568	<	* updating threads. The implementation performs internal sizing
569	<	* to try to accommodate this many threads.
570	<	* @throws IllegalArgumentException if the initial capacity is
571	<	* negative or the load factor or concurrencyLevel are
572	<	* nonpositive.
2034	>	* @return an enumeration of the values in this table
2035	>	* @see #values()
2036		*/
2037	<	public ConcurrentHashMap(int initialCapacity,
2038	<	float loadFactor, int concurrencyLevel) {
2039	<	if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
2040	<	throw new IllegalArgumentException();
2037	>	public Enumeration<V> elements() {
2038	>	Node<K,V>[] t;
2039	>	int f = (t = table) == null ? 0 : t.length;
2040	>	return new ValueIterator<K,V>(t, f, 0, f, this);
2041	>	}
2042
2043	<	if (concurrencyLevel > MAX_SEGMENTS)
580	<	concurrencyLevel = MAX_SEGMENTS;
2043	>	// ConcurrentHashMap-only methods
2044
2045	<	// Find power-of-two sizes best matching arguments
2046	<	int sshift = 0;
2047	<	int ssize = 1;
2048	<	while (ssize < concurrencyLevel) {
2049	<	++sshift;
2050	<	ssize <<= 1;
2051	<	}
2052	<	segmentShift = 32 - sshift;
2053	<	segmentMask = ssize - 1;
2054	<	this.segments = new Segment[ssize];
2055	<
2056	<	if (initialCapacity > MAXIMUM_CAPACITY)
2057	<	initialCapacity = MAXIMUM_CAPACITY;
595	<	int c = initialCapacity / ssize;
596	<	if (c * ssize < initialCapacity)
597	<	++c;
598	<	int cap = 1;
599	<	while (cap < c)
600	<	cap <<= 1;
601	<
602	<	for (int i = 0; i < this.segments.length; ++i)
603	<	this.segments[i] = new Segment<K,V>(cap, loadFactor);
2045	>	/**
2046	>	* Returns the number of mappings. This method should be used
2047	>	* instead of {@link #size} because a ConcurrentHashMap may
2048	>	* contain more mappings than can be represented as an int. The
2049	>	* value returned is an estimate; the actual count may differ if
2050	>	* there are concurrent insertions or removals.
2051	>	*
2052	>	* @return the number of mappings
2053	>	* @since 1.8
2054	>	*/
2055	>	public long mappingCount() {
2056	>	long n = sumCount();
2057	>	return (n < 0L) ? 0L : n; // ignore transient negative values
2058		}
2059
2060		/**
2061	<	* Creates a new, empty map with the specified initial
2062	<	* capacity,  and with default load factor (<tt>0.75f</tt>)
609	<	* and concurrencyLevel (<tt>16</tt>).
2061	>	* Creates a new {@link Set} backed by a ConcurrentHashMap
2062	>	* from the given type to {@code Boolean.TRUE}.
2063		*
2064	<	* @param initialCapacity the initial capacity. The implementation
2065	<	* performs internal sizing to accommodate this many elements.
2064	>	* @param <K> the element type of the returned set
2065	>	* @return the new set
2066	>	* @since 1.8
2067	>	*/
2068	>	public static <K> KeySetView<K,Boolean> newKeySet() {
2069	>	return new KeySetView<K,Boolean>
2070	>	(new ConcurrentHashMap<K,Boolean>(), Boolean.TRUE);
2071	>	}
2072	>
2073	>	/**
2074	>	* Creates a new {@link Set} backed by a ConcurrentHashMap
2075	>	* from the given type to {@code Boolean.TRUE}.
2076	>	*
2077	>	* @param initialCapacity The implementation performs internal
2078	>	* sizing to accommodate this many elements.
2079	>	* @param <K> the element type of the returned set
2080	>	* @return the new set
2081		* @throws IllegalArgumentException if the initial capacity of
2082	<	* elements is negative.
2082	>	* elements is negative
2083	>	* @since 1.8
2084		*/
2085	<	public ConcurrentHashMap(int initialCapacity) {
2086	<	this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2085	>	public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
2086	>	return new KeySetView<K,Boolean>
2087	>	(new ConcurrentHashMap<K,Boolean>(initialCapacity), Boolean.TRUE);
2088		}
2089
2090		/**
2091	<	* Creates a new, empty map with a default initial capacity
2092	<	* (<tt>16</tt>), load factor (<tt>0.75f</tt>) and
2093	<	* concurrencyLevel (<tt>16</tt>).
2091	>	* Returns a {@link Set} view of the keys in this map, using the
2092	>	* given common mapped value for any additions (i.e., {@link
2093	>	* Collection#add} and {@link Collection#addAll(Collection)}).
2094	>	* This is of course only appropriate if it is acceptable to use
2095	>	* the same value for all additions from this view.
2096	>	*
2097	>	* @param mappedValue the mapped value to use for any additions
2098	>	* @return the set view
2099	>	* @throws NullPointerException if the mappedValue is null
2100		*/
2101	<	public ConcurrentHashMap() {
2102	<	this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2101	>	public KeySetView<K,V> keySet(V mappedValue) {
2102	>	if (mappedValue == null)
2103	>	throw new NullPointerException();
2104	>	return new KeySetView<K,V>(this, mappedValue);
2105		}
2106
2107	+	/* ---------------- Special Nodes -------------- */
2108	+
2109		/**
2110	<	* Creates a new map with the same mappings as the given map.  The
631	<	* map is created with a capacity consistent with the default load
632	<	* factor (<tt>0.75f</tt>) and uses the default concurrencyLevel
633	<	* (<tt>16</tt>).
634	<	* @param t the map
2110	>	* A node inserted at head of bins during transfer operations.
2111		*/
2112	<	public ConcurrentHashMap(Map<? extends K, ? extends V> t) {
2113	<	this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1,
2114	<	DEFAULT_INITIAL_CAPACITY),
2115	<	DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2116	<	putAll(t);
2112	>	static final class ForwardingNode<K,V> extends Node<K,V> {
2113	>	final Node<K,V>[] nextTable;
2114	>	ForwardingNode(Node<K,V>[] tab) {
2115	>	super(MOVED, null, null, null);
2116	>	this.nextTable = tab;
2117	>	}
2118	>
2119	>	Node<K,V> find(int h, Object k) {
2120	>	// loop to avoid arbitrarily deep recursion on forwarding nodes
2121	>	outer: for (Node<K,V>[] tab = nextTable;;) {
2122	>	Node<K,V> e; int n;
2123	>	if (k == null || tab == null || (n = tab.length) == 0 ||
2124	>	(e = tabAt(tab, (n - 1) & h)) == null)
2125	>	return null;
2126	>	for (;;) {
2127	>	int eh; K ek;
2128	>	if ((eh = e.hash) == h &&
2129	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
2130	>	return e;
2131	>	if (eh < 0) {
2132	>	if (e instanceof ForwardingNode) {
2133	>	tab = ((ForwardingNode<K,V>)e).nextTable;
2134	>	continue outer;
2135	>	}
2136	>	else
2137	>	return e.find(h, k);
2138	>	}
2139	>	if ((e = e.next) == null)
2140	>	return null;
2141	>	}
2142	>	}
2143	>	}
2144		}
2145
2146	<	// inherit Map javadoc
2147	<	public boolean isEmpty() {
2148	<	final Segment[] segments = this.segments;
2149	<	/*
2150	<	* We keep track of per-segment modCounts to avoid ABA
2151	<	* problems in which an element in one segment was added and
649	<	* in another removed during traversal, in which case the
650	<	* table was never actually empty at any point. Note the
651	<	* similar use of modCounts in the size() and containsValue()
652	<	* methods, which are the only other methods also susceptible
653	<	* to ABA problems.
654	<	*/
655	<	int[] mc = new int[segments.length];
656	<	int mcsum = 0;
657	<	for (int i = 0; i < segments.length; ++i) {
658	<	if (segments[i].count != 0)
659	<	return false;
660	<	else
661	<	mcsum += mc[i] = segments[i].modCount;
2146	>	/**
2147	>	* A place-holder node used in computeIfAbsent and compute
2148	>	*/
2149	>	static final class ReservationNode<K,V> extends Node<K,V> {
2150	>	ReservationNode() {
2151	>	super(RESERVED, null, null, null);
2152		}
2153	<	// If mcsum happens to be zero, then we know we got a snapshot
2154	<	// before any modifications at all were made.  This is
2155	<	// probably common enough to bother tracking.
2156	<	if (mcsum != 0) {
2157	<	for (int i = 0; i < segments.length; ++i) {
2158	<	if (segments[i].count != 0 ||
2159	<	mc[i] != segments[i].modCount)
2160	<	return false;
2153	>
2154	>	Node<K,V> find(int h, Object k) {
2155	>	return null;
2156	>	}
2157	>	}
2158	>
2159	>	/* ---------------- Table Initialization and Resizing -------------- */
2160	>
2161	>	/**
2162	>	* Initializes table, using the size recorded in sizeCtl.
2163	>	*/
2164	>	private final Node<K,V>[] initTable() {
2165	>	Node<K,V>[] tab; int sc;
2166	>	while ((tab = table) == null || tab.length == 0) {
2167	>	if ((sc = sizeCtl) < 0)
2168	>	Thread.yield(); // lost initialization race; just spin
2169	>	else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2170	>	try {
2171	>	if ((tab = table) == null || tab.length == 0) {
2172	>	int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
2173	>	@SuppressWarnings({"rawtypes","unchecked"})
2174	>	Node<K,V>[] nt = (Node<K,V>[])new Node[n];
2175	>	table = tab = nt;
2176	>	sc = n - (n >>> 2);
2177	>	}
2178	>	} finally {
2179	>	sizeCtl = sc;
2180	>	}
2181	>	break;
2182		}
2183		}
2184	<	return true;
2184	>	return tab;
2185		}
2186
2187	<	// inherit Map javadoc
2188	<	public int size() {
2189	<	final Segment[] segments = this.segments;
2190	<	long sum = 0;
2191	<	long check = 0;
2192	<	int[] mc = new int[segments.length];
2193	<	// Try a few times to get accurate count. On failure due to
2194	<	// continuous async changes in table, resort to locking.
2195	<	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
2196	<	check = 0;
2197	<	sum = 0;
2198	<	int mcsum = 0;
2199	<	for (int i = 0; i < segments.length; ++i) {
2200	<	sum += segments[i].count;
2201	<	mcsum += mc[i] = segments[i].modCount;
2202	<	}
2203	<	if (mcsum != 0) {
2204	<	for (int i = 0; i < segments.length; ++i) {
2205	<	check += segments[i].count;
2206	<	if (mc[i] != segments[i].modCount) {
2207	<	check = -1; // force retry
2187	>	/**
2188	>	* Adds to count, and if table is too small and not already
2189	>	* resizing, initiates transfer. If already resizing, helps
2190	>	* perform transfer if work is available.  Rechecks occupancy
2191	>	* after a transfer to see if another resize is already needed
2192	>	* because resizings are lagging additions.
2193	>	*
2194	>	* @param x the count to add
2195	>	* @param check if <0, don't check resize, if <= 1 only check if uncontended
2196	>	*/
2197	>	private final void addCount(long x, int check) {
2198	>	CounterCell[] as; long b, s;
2199	>	if ((as = counterCells) != null ||
2200	>	!U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
2201	>	CounterCell a; long v; int m;
2202	>	boolean uncontended = true;
2203	>	if (as == null || (m = as.length - 1) < 0 ||
2204	>	(a = as[ThreadLocalRandom.getProbe() & m]) == null ||
2205	>	!(uncontended =
2206	>	U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
2207	>	fullAddCount(x, uncontended);
2208	>	return;
2209	>	}
2210	>	if (check <= 1)
2211	>	return;
2212	>	s = sumCount();
2213	>	}
2214	>	if (check >= 0) {
2215	>	Node<K,V>[] tab, nt; int sc;
2216	>	while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
2217	>	tab.length < MAXIMUM_CAPACITY) {
2218	>	if (sc < 0) {
2219	>	if (sc == -1 || transferIndex <= transferOrigin ||
2220	>	(nt = nextTable) == null)
2221		break;
2222	+	if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2223	+	transfer(tab, nt);
2224	+	}
2225	+	else if (U.compareAndSwapInt(this, SIZECTL, sc, -2))
2226	+	transfer(tab, null);
2227	+	s = sumCount();
2228	+	}
2229	+	}
2230	+	}
2231	+
2232	+	/**
2233	+	* Helps transfer if a resize is in progress.
2234	+	*/
2235	+	final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) {
2236	+	Node<K,V>[] nextTab; int sc;
2237	+	if ((f instanceof ForwardingNode) &&
2238	+	(nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) {
2239	+	if (nextTab == nextTable && tab == table &&
2240	+	transferIndex > transferOrigin && (sc = sizeCtl) < -1 &&
2241	+	U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2242	+	transfer(tab, nextTab);
2243	+	return nextTab;
2244	+	}
2245	+	return table;
2246	+	}
2247	+
2248	+	/**
2249	+	* Tries to presize table to accommodate the given number of elements.
2250	+	*
2251	+	* @param size number of elements (doesn't need to be perfectly accurate)
2252	+	*/
2253	+	private final void tryPresize(int size) {
2254	+	int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
2255	+	tableSizeFor(size + (size >>> 1) + 1);
2256	+	int sc;
2257	+	while ((sc = sizeCtl) >= 0) {
2258	+	Node<K,V>[] tab = table; int n;
2259	+	if (tab == null || (n = tab.length) == 0) {
2260	+	n = (sc > c) ? sc : c;
2261	+	if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2262	+	try {
2263	+	if (table == tab) {
2264	+	@SuppressWarnings({"rawtypes","unchecked"})
2265	+	Node<K,V>[] nt = (Node<K,V>[])new Node[n];
2266	+	table = nt;
2267	+	sc = n - (n >>> 2);
2268	+	}
2269	+	} finally {
2270	+	sizeCtl = sc;
2271		}
2272		}
2273		}
2274	<	if (check == sum)
2274	>	else if (c <= sc || n >= MAXIMUM_CAPACITY)
2275		break;
2276	+	else if (tab == table &&
2277	+	U.compareAndSwapInt(this, SIZECTL, sc, -2))
2278	+	transfer(tab, null);
2279		}
704	–	if (check != sum) { // Resort to locking all segments
705	–	sum = 0;
706	–	for (int i = 0; i < segments.length; ++i)
707	–	segments[i].lock();
708	–	for (int i = 0; i < segments.length; ++i)
709	–	sum += segments[i].count;
710	–	for (int i = 0; i < segments.length; ++i)
711	–	segments[i].unlock();
712	–	}
713	–	if (sum > Integer.MAX_VALUE)
714	–	return Integer.MAX_VALUE;
715	–	else
716	–	return (int)sum;
2280		}
2281
2282	+	/**
2283	+	* Moves and/or copies the nodes in each bin to new table. See
2284	+	* above for explanation.
2285	+	*/
2286	+	private final void transfer(Node<K,V>[] tab, Node<K,V>[] nextTab) {
2287	+	int n = tab.length, stride;
2288	+	if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
2289	+	stride = MIN_TRANSFER_STRIDE; // subdivide range
2290	+	if (nextTab == null) {            // initiating
2291	+	try {
2292	+	@SuppressWarnings({"rawtypes","unchecked"})
2293	+	Node<K,V>[] nt = (Node<K,V>[])new Node[n << 1];
2294	+	nextTab = nt;
2295	+	} catch (Throwable ex) {      // try to cope with OOME
2296	+	sizeCtl = Integer.MAX_VALUE;
2297	+	return;
2298	+	}
2299	+	nextTable = nextTab;
2300	+	transferOrigin = n;
2301	+	transferIndex = n;
2302	+	ForwardingNode<K,V> rev = new ForwardingNode<K,V>(tab);
2303	+	for (int k = n; k > 0;) {    // progressively reveal ready slots
2304	+	int nextk = (k > stride) ? k - stride : 0;
2305	+	for (int m = nextk; m < k; ++m)
2306	+	nextTab[m] = rev;
2307	+	for (int m = n + nextk; m < n + k; ++m)
2308	+	nextTab[m] = rev;
2309	+	U.putOrderedInt(this, TRANSFERORIGIN, k = nextk);
2310	+	}
2311	+	}
2312	+	int nextn = nextTab.length;
2313	+	ForwardingNode<K,V> fwd = new ForwardingNode<K,V>(nextTab);
2314	+	boolean advance = true;
2315	+	boolean finishing = false; // to ensure sweep before committing nextTab
2316	+	for (int i = 0, bound = 0;;) {
2317	+	int nextIndex, nextBound, fh; Node<K,V> f;
2318	+	while (advance) {
2319	+	if (--i >= bound || finishing)
2320	+	advance = false;
2321	+	else if ((nextIndex = transferIndex) <= transferOrigin) {
2322	+	i = -1;
2323	+	advance = false;
2324	+	}
2325	+	else if (U.compareAndSwapInt
2326	+	(this, TRANSFERINDEX, nextIndex,
2327	+	nextBound = (nextIndex > stride ?
2328	+	nextIndex - stride : 0))) {
2329	+	bound = nextBound;
2330	+	i = nextIndex - 1;
2331	+	advance = false;
2332	+	}
2333	+	}
2334	+	if (i < 0 || i >= n || i + n >= nextn) {
2335	+	if (finishing) {
2336	+	nextTable = null;
2337	+	table = nextTab;
2338	+	sizeCtl = (n << 1) - (n >>> 1);
2339	+	return;
2340	+	}
2341	+	for (int sc;;) {
2342	+	if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) {
2343	+	if (sc != -1)
2344	+	return;
2345	+	finishing = advance = true;
2346	+	i = n; // recheck before commit
2347	+	break;
2348	+	}
2349	+	}
2350	+	}
2351	+	else if ((f = tabAt(tab, i)) == null) {
2352	+	if (casTabAt(tab, i, null, fwd)) {
2353	+	setTabAt(nextTab, i, null);
2354	+	setTabAt(nextTab, i + n, null);
2355	+	advance = true;
2356	+	}
2357	+	}
2358	+	else if ((fh = f.hash) == MOVED)
2359	+	advance = true; // already processed
2360	+	else {
2361	+	synchronized (f) {
2362	+	if (tabAt(tab, i) == f) {
2363	+	Node<K,V> ln, hn;
2364	+	if (fh >= 0) {
2365	+	int runBit = fh & n;
2366	+	Node<K,V> lastRun = f;
2367	+	for (Node<K,V> p = f.next; p != null; p = p.next) {
2368	+	int b = p.hash & n;
2369	+	if (b != runBit) {
2370	+	runBit = b;
2371	+	lastRun = p;
2372	+	}
2373	+	}
2374	+	if (runBit == 0) {
2375	+	ln = lastRun;
2376	+	hn = null;
2377	+	}
2378	+	else {
2379	+	hn = lastRun;
2380	+	ln = null;
2381	+	}
2382	+	for (Node<K,V> p = f; p != lastRun; p = p.next) {
2383	+	int ph = p.hash; K pk = p.key; V pv = p.val;
2384	+	if ((ph & n) == 0)
2385	+	ln = new Node<K,V>(ph, pk, pv, ln);
2386	+	else
2387	+	hn = new Node<K,V>(ph, pk, pv, hn);
2388	+	}
2389	+	setTabAt(nextTab, i, ln);
2390	+	setTabAt(nextTab, i + n, hn);
2391	+	setTabAt(tab, i, fwd);
2392	+	advance = true;
2393	+	}
2394	+	else if (f instanceof TreeBin) {
2395	+	TreeBin<K,V> t = (TreeBin<K,V>)f;
2396	+	TreeNode<K,V> lo = null, loTail = null;
2397	+	TreeNode<K,V> hi = null, hiTail = null;
2398	+	int lc = 0, hc = 0;
2399	+	for (Node<K,V> e = t.first; e != null; e = e.next) {
2400	+	int h = e.hash;
2401	+	TreeNode<K,V> p = new TreeNode<K,V>
2402	+	(h, e.key, e.val, null, null);
2403	+	if ((h & n) == 0) {
2404	+	if ((p.prev = loTail) == null)
2405	+	lo = p;
2406	+	else
2407	+	loTail.next = p;
2408	+	loTail = p;
2409	+	++lc;
2410	+	}
2411	+	else {
2412	+	if ((p.prev = hiTail) == null)
2413	+	hi = p;
2414	+	else
2415	+	hiTail.next = p;
2416	+	hiTail = p;
2417	+	++hc;
2418	+	}
2419	+	}
2420	+	ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) :
2421	+	(hc != 0) ? new TreeBin<K,V>(lo) : t;
2422	+	hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
2423	+	(lc != 0) ? new TreeBin<K,V>(hi) : t;
2424	+	setTabAt(nextTab, i, ln);
2425	+	setTabAt(nextTab, i + n, hn);
2426	+	setTabAt(tab, i, fwd);
2427	+	advance = true;
2428	+	}
2429	+	}
2430	+	}
2431	+	}
2432	+	}
2433	+	}
2434	+
2435	+	/* ---------------- Counter support -------------- */
2436
2437		/**
2438	<	* Returns the value to which the specified key is mapped in this table.
2439	<	*
723	<	* @param   key   a key in the table.
724	<	* @return  the value to which the key is mapped in this table;
725	<	*          <tt>null</tt> if the key is not mapped to any value in
726	<	*          this table.
727	<	* @throws  NullPointerException  if the key is
728	<	*               <tt>null</tt>.
2438	>	* A padded cell for distributing counts.  Adapted from LongAdder
2439	>	* and Striped64.  See their internal docs for explanation.
2440		*/
2441	<	public V get(Object key) {
2442	<	int hash = hash(key); // throws NullPointerException if key null
2443	<	return segmentFor(hash).get(key, hash);
2441	>	@sun.misc.Contended static final class CounterCell {
2442	>	volatile long value;
2443	>	CounterCell(long x) { value = x; }
2444	>	}
2445	>
2446	>	final long sumCount() {
2447	>	CounterCell[] as = counterCells; CounterCell a;
2448	>	long sum = baseCount;
2449	>	if (as != null) {
2450	>	for (int i = 0; i < as.length; ++i) {
2451	>	if ((a = as[i]) != null)
2452	>	sum += a.value;
2453	>	}
2454	>	}
2455	>	return sum;
2456	>	}
2457	>
2458	>	// See LongAdder version for explanation
2459	>	private final void fullAddCount(long x, boolean wasUncontended) {
2460	>	int h;
2461	>	if ((h = ThreadLocalRandom.getProbe()) == 0) {
2462	>	ThreadLocalRandom.localInit();      // force initialization
2463	>	h = ThreadLocalRandom.getProbe();
2464	>	wasUncontended = true;
2465	>	}
2466	>	boolean collide = false;                // True if last slot nonempty
2467	>	for (;;) {
2468	>	CounterCell[] as; CounterCell a; int n; long v;
2469	>	if ((as = counterCells) != null && (n = as.length) > 0) {
2470	>	if ((a = as[(n - 1) & h]) == null) {
2471	>	if (cellsBusy == 0) {            // Try to attach new Cell
2472	>	CounterCell r = new CounterCell(x); // Optimistic create
2473	>	if (cellsBusy == 0 &&
2474	>	U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2475	>	boolean created = false;
2476	>	try {               // Recheck under lock
2477	>	CounterCell[] rs; int m, j;
2478	>	if ((rs = counterCells) != null &&
2479	>	(m = rs.length) > 0 &&
2480	>	rs[j = (m - 1) & h] == null) {
2481	>	rs[j] = r;
2482	>	created = true;
2483	>	}
2484	>	} finally {
2485	>	cellsBusy = 0;
2486	>	}
2487	>	if (created)
2488	>	break;
2489	>	continue;           // Slot is now non-empty
2490	>	}
2491	>	}
2492	>	collide = false;
2493	>	}
2494	>	else if (!wasUncontended)       // CAS already known to fail
2495	>	wasUncontended = true;      // Continue after rehash
2496	>	else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
2497	>	break;
2498	>	else if (counterCells != as || n >= NCPU)
2499	>	collide = false;            // At max size or stale
2500	>	else if (!collide)
2501	>	collide = true;
2502	>	else if (cellsBusy == 0 &&
2503	>	U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2504	>	try {
2505	>	if (counterCells == as) {// Expand table unless stale
2506	>	CounterCell[] rs = new CounterCell[n << 1];
2507	>	for (int i = 0; i < n; ++i)
2508	>	rs[i] = as[i];
2509	>	counterCells = rs;
2510	>	}
2511	>	} finally {
2512	>	cellsBusy = 0;
2513	>	}
2514	>	collide = false;
2515	>	continue;                   // Retry with expanded table
2516	>	}
2517	>	h = ThreadLocalRandom.advanceProbe(h);
2518	>	}
2519	>	else if (cellsBusy == 0 && counterCells == as &&
2520	>	U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2521	>	boolean init = false;
2522	>	try {                           // Initialize table
2523	>	if (counterCells == as) {
2524	>	CounterCell[] rs = new CounterCell[2];
2525	>	rs[h & 1] = new CounterCell(x);
2526	>	counterCells = rs;
2527	>	init = true;
2528	>	}
2529	>	} finally {
2530	>	cellsBusy = 0;
2531	>	}
2532	>	if (init)
2533	>	break;
2534	>	}
2535	>	else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
2536	>	break;                          // Fall back on using base
2537	>	}
2538		}
2539
2540	+	/* ---------------- Conversion from/to TreeBins -------------- */
2541	+
2542		/**
2543	<	* Tests if the specified object is a key in this table.
2544	<	*
738	<	* @param   key   possible key.
739	<	* @return  <tt>true</tt> if and only if the specified object
740	<	*          is a key in this table, as determined by the
741	<	*          <tt>equals</tt> method; <tt>false</tt> otherwise.
742	<	* @throws  NullPointerException  if the key is
743	<	*               <tt>null</tt>.
2543	>	* Replaces all linked nodes in bin at given index unless table is
2544	>	* too small, in which case resizes instead.
2545		*/
2546	<	public boolean containsKey(Object key) {
2547	<	int hash = hash(key); // throws NullPointerException if key null
2548	<	return segmentFor(hash).containsKey(key, hash);
2546	>	private final void treeifyBin(Node<K,V>[] tab, int index) {
2547	>	Node<K,V> b; int n, sc;
2548	>	if (tab != null) {
2549	>	if ((n = tab.length) < MIN_TREEIFY_CAPACITY) {
2550	>	if (tab == table && (sc = sizeCtl) >= 0 &&
2551	>	U.compareAndSwapInt(this, SIZECTL, sc, -2))
2552	>	transfer(tab, null);
2553	>	}
2554	>	else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
2555	>	synchronized (b) {
2556	>	if (tabAt(tab, index) == b) {
2557	>	TreeNode<K,V> hd = null, tl = null;
2558	>	for (Node<K,V> e = b; e != null; e = e.next) {
2559	>	TreeNode<K,V> p =
2560	>	new TreeNode<K,V>(e.hash, e.key, e.val,
2561	>	null, null);
2562	>	if ((p.prev = tl) == null)
2563	>	hd = p;
2564	>	else
2565	>	tl.next = p;
2566	>	tl = p;
2567	>	}
2568	>	setTabAt(tab, index, new TreeBin<K,V>(hd));
2569	>	}
2570	>	}
2571	>	}
2572	>	}
2573		}
2574
2575		/**
2576	<	* Returns <tt>true</tt> if this map maps one or more keys to the
752	<	* specified value. Note: This method requires a full internal
753	<	* traversal of the hash table, and so is much slower than
754	<	* method <tt>containsKey</tt>.
755	<	*
756	<	* @param value value whose presence in this map is to be tested.
757	<	* @return <tt>true</tt> if this map maps one or more keys to the
758	<	* specified value.
759	<	* @throws  NullPointerException  if the value is <tt>null</tt>.
2576	>	* Returns a list on non-TreeNodes replacing those in given list.
2577		*/
2578	<	public boolean containsValue(Object value) {
2579	<	if (value == null)
2580	<	throw new NullPointerException();
2581	<
2582	<	// See explanation of modCount use above
2578	>	static <K,V> Node<K,V> untreeify(Node<K,V> b) {
2579	>	Node<K,V> hd = null, tl = null;
2580	>	for (Node<K,V> q = b; q != null; q = q.next) {
2581	>	Node<K,V> p = new Node<K,V>(q.hash, q.key, q.val, null);
2582	>	if (tl == null)
2583	>	hd = p;
2584	>	else
2585	>	tl.next = p;
2586	>	tl = p;
2587	>	}
2588	>	return hd;
2589	>	}
2590
2591	<	final Segment[] segments = this.segments;
768	<	int[] mc = new int[segments.length];
2591	>	/* ---------------- TreeNodes -------------- */
2592
2593	<	// Try a few times without locking
2594	<	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
2595	<	int sum = 0;
2596	<	int mcsum = 0;
2597	<	for (int i = 0; i < segments.length; ++i) {
2598	<	int c = segments[i].count;
2599	<	mcsum += mc[i] = segments[i].modCount;
2600	<	if (segments[i].containsValue(value))
2601	<	return true;
2593	>	/**
2594	>	* Nodes for use in TreeBins
2595	>	*/
2596	>	static final class TreeNode<K,V> extends Node<K,V> {
2597	>	TreeNode<K,V> parent;  // red-black tree links
2598	>	TreeNode<K,V> left;
2599	>	TreeNode<K,V> right;
2600	>	TreeNode<K,V> prev;    // needed to unlink next upon deletion
2601	>	boolean red;
2602	>
2603	>	TreeNode(int hash, K key, V val, Node<K,V> next,
2604	>	TreeNode<K,V> parent) {
2605	>	super(hash, key, val, next);
2606	>	this.parent = parent;
2607	>	}
2608	>
2609	>	Node<K,V> find(int h, Object k) {
2610	>	return findTreeNode(h, k, null);
2611	>	}
2612	>
2613	>	/**
2614	>	* Returns the TreeNode (or null if not found) for the given key
2615	>	* starting at given root.
2616	>	*/
2617	>	final TreeNode<K,V> findTreeNode(int h, Object k, Class<?> kc) {
2618	>	if (k != null) {
2619	>	TreeNode<K,V> p = this;
2620	>	do  {
2621	>	int ph, dir; K pk; TreeNode<K,V> q;
2622	>	TreeNode<K,V> pl = p.left, pr = p.right;
2623	>	if ((ph = p.hash) > h)
2624	>	p = pl;
2625	>	else if (ph < h)
2626	>	p = pr;
2627	>	else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2628	>	return p;
2629	>	else if (pl == null)
2630	>	p = pr;
2631	>	else if (pr == null)
2632	>	p = pl;
2633	>	else if ((kc != null ||
2634	>	(kc = comparableClassFor(k)) != null) &&
2635	>	(dir = compareComparables(kc, k, pk)) != 0)
2636	>	p = (dir < 0) ? pl : pr;
2637	>	else if ((q = pr.findTreeNode(h, k, kc)) != null)
2638	>	return q;
2639	>	else
2640	>	p = pl;
2641	>	} while (p != null);
2642		}
2643	<	boolean cleanSweep = true;
2644	<	if (mcsum != 0) {
2645	<	for (int i = 0; i < segments.length; ++i) {
2646	<	int c = segments[i].count;
2647	<	if (mc[i] != segments[i].modCount) {
2648	<	cleanSweep = false;
2649	<	break;
2643	>	return null;
2644	>	}
2645	>	}
2646	>
2647	>	/* ---------------- TreeBins -------------- */
2648	>
2649	>	/**
2650	>	* TreeNodes used at the heads of bins. TreeBins do not hold user
2651	>	* keys or values, but instead point to list of TreeNodes and
2652	>	* their root. They also maintain a parasitic read-write lock
2653	>	* forcing writers (who hold bin lock) to wait for readers (who do
2654	>	* not) to complete before tree restructuring operations.
2655	>	*/
2656	>	static final class TreeBin<K,V> extends Node<K,V> {
2657	>	TreeNode<K,V> root;
2658	>	volatile TreeNode<K,V> first;
2659	>	volatile Thread waiter;
2660	>	volatile int lockState;
2661	>	// values for lockState
2662	>	static final int WRITER = 1; // set while holding write lock
2663	>	static final int WAITER = 2; // set when waiting for write lock
2664	>	static final int READER = 4; // increment value for setting read lock
2665	>
2666	>	/**
2667	>	* Tie-breaking utility for ordering insertions when equal
2668	>	* hashCodes and non-comparable. We don't require a total
2669	>	* order, just a consistent insertion rule to maintain
2670	>	* equivalence across rebalancings. Tie-breaking further than
2671	>	* necessary simplifies testing a bit.
2672	>	*/
2673	>	static int tieBreakOrder(Object a, Object b) {
2674	>	int d;
2675	>	if (a == null || b == null ||
2676	>	(d = a.getClass().getName().
2677	>	compareTo(b.getClass().getName())) == 0)
2678	>	d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
2679	>	-1 : 1);
2680	>	return d;
2681	>	}
2682	>
2683	>	/**
2684	>	* Creates bin with initial set of nodes headed by b.
2685	>	*/
2686	>	TreeBin(TreeNode<K,V> b) {
2687	>	super(TREEBIN, null, null, null);
2688	>	this.first = b;
2689	>	TreeNode<K,V> r = null;
2690	>	for (TreeNode<K,V> x = b, next; x != null; x = next) {
2691	>	next = (TreeNode<K,V>)x.next;
2692	>	x.left = x.right = null;
2693	>	if (r == null) {
2694	>	x.parent = null;
2695	>	x.red = false;
2696	>	r = x;
2697	>	}
2698	>	else {
2699	>	K k = x.key;
2700	>	int h = x.hash;
2701	>	Class<?> kc = null;
2702	>	for (TreeNode<K,V> p = r;;) {
2703	>	int dir, ph;
2704	>	K pk = p.key;
2705	>	if ((ph = p.hash) > h)
2706	>	dir = -1;
2707	>	else if (ph < h)
2708	>	dir = 1;
2709	>	else if ((kc == null &&
2710	>	(kc = comparableClassFor(k)) == null) ||
2711	>	(dir = compareComparables(kc, k, pk)) == 0)
2712	>	dir = tieBreakOrder(k, pk);
2713	>	TreeNode<K,V> xp = p;
2714	>	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2715	>	x.parent = xp;
2716	>	if (dir <= 0)
2717	>	xp.left = x;
2718	>	else
2719	>	xp.right = x;
2720	>	r = balanceInsertion(r, x);
2721	>	break;
2722	>	}
2723		}
2724		}
2725		}
2726	<	if (cleanSweep)
2727	<	return false;
2726	>	this.root = r;
2727	>	assert checkInvariants(root);
2728		}
2729	<	// Resort to locking all segments
2730	<	for (int i = 0; i < segments.length; ++i)
2731	<	segments[i].lock();
2732	<	boolean found = false;
2733	<	try {
2734	<	for (int i = 0; i < segments.length; ++i) {
2735	<	if (segments[i].containsValue(value)) {
2736	<	found = true;
2729	>
2730	>	/**
2731	>	* Acquires write lock for tree restructuring.
2732	>	*/
2733	>	private final void lockRoot() {
2734	>	if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER))
2735	>	contendedLock(); // offload to separate method
2736	>	}
2737	>
2738	>	/**
2739	>	* Releases write lock for tree restructuring.
2740	>	*/
2741	>	private final void unlockRoot() {
2742	>	lockState = 0;
2743	>	}
2744	>
2745	>	/**
2746	>	* Possibly blocks awaiting root lock.
2747	>	*/
2748	>	private final void contendedLock() {
2749	>	boolean waiting = false;
2750	>	for (int s;;) {
2751	>	if (((s = lockState) & WRITER) == 0) {
2752	>	if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
2753	>	if (waiting)
2754	>	waiter = null;
2755	>	return;
2756	>	}
2757	>	}
2758	>	else if ((s | WAITER) == 0) {
2759	>	if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
2760	>	waiting = true;
2761	>	waiter = Thread.currentThread();
2762	>	}
2763	>	}
2764	>	else if (waiting)
2765	>	LockSupport.park(this);
2766	>	}
2767	>	}
2768	>
2769	>	/**
2770	>	* Returns matching node or null if none. Tries to search
2771	>	* using tree comparisons from root, but continues linear
2772	>	* search when lock not available.
2773	>	*/
2774	>	final Node<K,V> find(int h, Object k) {
2775	>	if (k != null) {
2776	>	for (Node<K,V> e = first; e != null; e = e.next) {
2777	>	int s; K ek;
2778	>	if (((s = lockState) & (WAITER|WRITER)) != 0) {
2779	>	if (e.hash == h &&
2780	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
2781	>	return e;
2782	>	}
2783	>	else if (U.compareAndSwapInt(this, LOCKSTATE, s,
2784	>	s + READER)) {
2785	>	TreeNode<K,V> r, p;
2786	>	try {
2787	>	p = ((r = root) == null ? null :
2788	>	r.findTreeNode(h, k, null));
2789	>	} finally {
2790	>	Thread w;
2791	>	if (U.getAndAddInt(this, LOCKSTATE, -READER) ==
2792	>	(READER|WAITER) && (w = waiter) != null)
2793	>	LockSupport.unpark(w);
2794	>	}
2795	>	return p;
2796	>	}
2797	>	}
2798	>	}
2799	>	return null;
2800	>	}
2801	>
2802	>	/**
2803	>	* Finds or adds a node.
2804	>	* @return null if added
2805	>	*/
2806	>	final TreeNode<K,V> putTreeVal(int h, K k, V v) {
2807	>	Class<?> kc = null;
2808	>	boolean searched = false;
2809	>	for (TreeNode<K,V> p = root;;) {
2810	>	int dir, ph; K pk;
2811	>	if (p == null) {
2812	>	first = root = new TreeNode<K,V>(h, k, v, null, null);
2813		break;
2814		}
2815	+	else if ((ph = p.hash) > h)
2816	+	dir = -1;
2817	+	else if (ph < h)
2818	+	dir = 1;
2819	+	else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2820	+	return p;
2821	+	else if ((kc == null &&
2822	+	(kc = comparableClassFor(k)) == null) ||
2823	+	(dir = compareComparables(kc, k, pk)) == 0) {
2824	+	if (!searched) {
2825	+	TreeNode<K,V> q, ch;
2826	+	searched = true;
2827	+	if (((ch = p.left) != null &&
2828	+	(q = ch.findTreeNode(h, k, kc)) != null) ||
2829	+	((ch = p.right) != null &&
2830	+	(q = ch.findTreeNode(h, k, kc)) != null))
2831	+	return q;
2832	+	}
2833	+	dir = tieBreakOrder(k, pk);
2834	+	}
2835	+
2836	+	TreeNode<K,V> xp = p;
2837	+	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2838	+	TreeNode<K,V> x, f = first;
2839	+	first = x = new TreeNode<K,V>(h, k, v, f, xp);
2840	+	if (f != null)
2841	+	f.prev = x;
2842	+	if (dir <= 0)
2843	+	xp.left = x;
2844	+	else
2845	+	xp.right = x;
2846	+	if (!xp.red)
2847	+	x.red = true;
2848	+	else {
2849	+	lockRoot();
2850	+	try {
2851	+	root = balanceInsertion(root, x);
2852	+	} finally {
2853	+	unlockRoot();
2854	+	}
2855	+	}
2856	+	break;
2857	+	}
2858	+	}
2859	+	assert checkInvariants(root);
2860	+	return null;
2861	+	}
2862	+
2863	+	/**
2864	+	* Removes the given node, that must be present before this
2865	+	* call.  This is messier than typical red-black deletion code
2866	+	* because we cannot swap the contents of an interior node
2867	+	* with a leaf successor that is pinned by "next" pointers
2868	+	* that are accessible independently of lock. So instead we
2869	+	* swap the tree linkages.
2870	+	*
2871	+	* @return true if now too small, so should be untreeified
2872	+	*/
2873	+	final boolean removeTreeNode(TreeNode<K,V> p) {
2874	+	TreeNode<K,V> next = (TreeNode<K,V>)p.next;
2875	+	TreeNode<K,V> pred = p.prev;  // unlink traversal pointers
2876	+	TreeNode<K,V> r, rl;
2877	+	if (pred == null)
2878	+	first = next;
2879	+	else
2880	+	pred.next = next;
2881	+	if (next != null)
2882	+	next.prev = pred;
2883	+	if (first == null) {
2884	+	root = null;
2885	+	return true;
2886	+	}
2887	+	if ((r = root) == null || r.right == null || // too small
2888	+	(rl = r.left) == null || rl.left == null)
2889	+	return true;
2890	+	lockRoot();
2891	+	try {
2892	+	TreeNode<K,V> replacement;
2893	+	TreeNode<K,V> pl = p.left;
2894	+	TreeNode<K,V> pr = p.right;
2895	+	if (pl != null && pr != null) {
2896	+	TreeNode<K,V> s = pr, sl;
2897	+	while ((sl = s.left) != null) // find successor
2898	+	s = sl;
2899	+	boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2900	+	TreeNode<K,V> sr = s.right;
2901	+	TreeNode<K,V> pp = p.parent;
2902	+	if (s == pr) { // p was s's direct parent
2903	+	p.parent = s;
2904	+	s.right = p;
2905	+	}
2906	+	else {
2907	+	TreeNode<K,V> sp = s.parent;
2908	+	if ((p.parent = sp) != null) {
2909	+	if (s == sp.left)
2910	+	sp.left = p;
2911	+	else
2912	+	sp.right = p;
2913	+	}
2914	+	if ((s.right = pr) != null)
2915	+	pr.parent = s;
2916	+	}
2917	+	p.left = null;
2918	+	if ((p.right = sr) != null)
2919	+	sr.parent = p;
2920	+	if ((s.left = pl) != null)
2921	+	pl.parent = s;
2922	+	if ((s.parent = pp) == null)
2923	+	r = s;
2924	+	else if (p == pp.left)
2925	+	pp.left = s;
2926	+	else
2927	+	pp.right = s;
2928	+	if (sr != null)
2929	+	replacement = sr;
2930	+	else
2931	+	replacement = p;
2932	+	}
2933	+	else if (pl != null)
2934	+	replacement = pl;
2935	+	else if (pr != null)
2936	+	replacement = pr;
2937	+	else
2938	+	replacement = p;
2939	+	if (replacement != p) {
2940	+	TreeNode<K,V> pp = replacement.parent = p.parent;
2941	+	if (pp == null)
2942	+	r = replacement;
2943	+	else if (p == pp.left)
2944	+	pp.left = replacement;
2945	+	else
2946	+	pp.right = replacement;
2947	+	p.left = p.right = p.parent = null;
2948	+	}
2949	+
2950	+	root = (p.red) ? r : balanceDeletion(r, replacement);
2951	+
2952	+	if (p == replacement) {  // detach pointers
2953	+	TreeNode<K,V> pp;
2954	+	if ((pp = p.parent) != null) {
2955	+	if (p == pp.left)
2956	+	pp.left = null;
2957	+	else if (p == pp.right)
2958	+	pp.right = null;
2959	+	p.parent = null;
2960	+	}
2961	+	}
2962	+	} finally {
2963	+	unlockRoot();
2964	+	}
2965	+	assert checkInvariants(root);
2966	+	return false;
2967	+	}
2968	+
2969	+	/* ------------------------------------------------------------ */
2970	+	// Red-black tree methods, all adapted from CLR
2971	+
2972	+	static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2973	+	TreeNode<K,V> p) {
2974	+	TreeNode<K,V> r, pp, rl;
2975	+	if (p != null && (r = p.right) != null) {
2976	+	if ((rl = p.right = r.left) != null)
2977	+	rl.parent = p;
2978	+	if ((pp = r.parent = p.parent) == null)
2979	+	(root = r).red = false;
2980	+	else if (pp.left == p)
2981	+	pp.left = r;
2982	+	else
2983	+	pp.right = r;
2984	+	r.left = p;
2985	+	p.parent = r;
2986	+	}
2987	+	return root;
2988	+	}
2989	+
2990	+	static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2991	+	TreeNode<K,V> p) {
2992	+	TreeNode<K,V> l, pp, lr;
2993	+	if (p != null && (l = p.left) != null) {
2994	+	if ((lr = p.left = l.right) != null)
2995	+	lr.parent = p;
2996	+	if ((pp = l.parent = p.parent) == null)
2997	+	(root = l).red = false;
2998	+	else if (pp.right == p)
2999	+	pp.right = l;
3000	+	else
3001	+	pp.left = l;
3002	+	l.right = p;
3003	+	p.parent = l;
3004	+	}
3005	+	return root;
3006	+	}
3007	+
3008	+	static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
3009	+	TreeNode<K,V> x) {
3010	+	x.red = true;
3011	+	for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
3012	+	if ((xp = x.parent) == null) {
3013	+	x.red = false;
3014	+	return x;
3015	+	}
3016	+	else if (!xp.red || (xpp = xp.parent) == null)
3017	+	return root;
3018	+	if (xp == (xppl = xpp.left)) {
3019	+	if ((xppr = xpp.right) != null && xppr.red) {
3020	+	xppr.red = false;
3021	+	xp.red = false;
3022	+	xpp.red = true;
3023	+	x = xpp;
3024	+	}
3025	+	else {
3026	+	if (x == xp.right) {
3027	+	root = rotateLeft(root, x = xp);
3028	+	xpp = (xp = x.parent) == null ? null : xp.parent;
3029	+	}
3030	+	if (xp != null) {
3031	+	xp.red = false;
3032	+	if (xpp != null) {
3033	+	xpp.red = true;
3034	+	root = rotateRight(root, xpp);
3035	+	}
3036	+	}
3037	+	}
3038	+	}
3039	+	else {
3040	+	if (xppl != null && xppl.red) {
3041	+	xppl.red = false;
3042	+	xp.red = false;
3043	+	xpp.red = true;
3044	+	x = xpp;
3045	+	}
3046	+	else {
3047	+	if (x == xp.left) {
3048	+	root = rotateRight(root, x = xp);
3049	+	xpp = (xp = x.parent) == null ? null : xp.parent;
3050	+	}
3051	+	if (xp != null) {
3052	+	xp.red = false;
3053	+	if (xpp != null) {
3054	+	xpp.red = true;
3055	+	root = rotateLeft(root, xpp);
3056	+	}
3057	+	}
3058	+	}
3059	+	}
3060	+	}
3061	+	}
3062	+
3063	+	static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
3064	+	TreeNode<K,V> x) {
3065	+	for (TreeNode<K,V> xp, xpl, xpr;;)  {
3066	+	if (x == null || x == root)
3067	+	return root;
3068	+	else if ((xp = x.parent) == null) {
3069	+	x.red = false;
3070	+	return x;
3071	+	}
3072	+	else if (x.red) {
3073	+	x.red = false;
3074	+	return root;
3075	+	}
3076	+	else if ((xpl = xp.left) == x) {
3077	+	if ((xpr = xp.right) != null && xpr.red) {
3078	+	xpr.red = false;
3079	+	xp.red = true;
3080	+	root = rotateLeft(root, xp);
3081	+	xpr = (xp = x.parent) == null ? null : xp.right;
3082	+	}
3083	+	if (xpr == null)
3084	+	x = xp;
3085	+	else {
3086	+	TreeNode<K,V> sl = xpr.left, sr = xpr.right;
3087	+	if ((sr == null || !sr.red) &&
3088	+	(sl == null || !sl.red)) {
3089	+	xpr.red = true;
3090	+	x = xp;
3091	+	}
3092	+	else {
3093	+	if (sr == null || !sr.red) {
3094	+	if (sl != null)
3095	+	sl.red = false;
3096	+	xpr.red = true;
3097	+	root = rotateRight(root, xpr);
3098	+	xpr = (xp = x.parent) == null ?
3099	+	null : xp.right;
3100	+	}
3101	+	if (xpr != null) {
3102	+	xpr.red = (xp == null) ? false : xp.red;
3103	+	if ((sr = xpr.right) != null)
3104	+	sr.red = false;
3105	+	}
3106	+	if (xp != null) {
3107	+	xp.red = false;
3108	+	root = rotateLeft(root, xp);
3109	+	}
3110	+	x = root;
3111	+	}
3112	+	}
3113	+	}
3114	+	else { // symmetric
3115	+	if (xpl != null && xpl.red) {
3116	+	xpl.red = false;
3117	+	xp.red = true;
3118	+	root = rotateRight(root, xp);
3119	+	xpl = (xp = x.parent) == null ? null : xp.left;
3120	+	}
3121	+	if (xpl == null)
3122	+	x = xp;
3123	+	else {
3124	+	TreeNode<K,V> sl = xpl.left, sr = xpl.right;
3125	+	if ((sl == null || !sl.red) &&
3126	+	(sr == null || !sr.red)) {
3127	+	xpl.red = true;
3128	+	x = xp;
3129	+	}
3130	+	else {
3131	+	if (sl == null || !sl.red) {
3132	+	if (sr != null)
3133	+	sr.red = false;
3134	+	xpl.red = true;
3135	+	root = rotateLeft(root, xpl);
3136	+	xpl = (xp = x.parent) == null ?
3137	+	null : xp.left;
3138	+	}
3139	+	if (xpl != null) {
3140	+	xpl.red = (xp == null) ? false : xp.red;
3141	+	if ((sl = xpl.left) != null)
3142	+	sl.red = false;
3143	+	}
3144	+	if (xp != null) {
3145	+	xp.red = false;
3146	+	root = rotateRight(root, xp);
3147	+	}
3148	+	x = root;
3149	+	}
3150	+	}
3151	+	}
3152	+	}
3153	+	}
3154	+
3155	+	/**
3156	+	* Recursive invariant check
3157	+	*/
3158	+	static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
3159	+	TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
3160	+	tb = t.prev, tn = (TreeNode<K,V>)t.next;
3161	+	if (tb != null && tb.next != t)
3162	+	return false;
3163	+	if (tn != null && tn.prev != t)
3164	+	return false;
3165	+	if (tp != null && t != tp.left && t != tp.right)
3166	+	return false;
3167	+	if (tl != null && (tl.parent != t || tl.hash > t.hash))
3168	+	return false;
3169	+	if (tr != null && (tr.parent != t || tr.hash < t.hash))
3170	+	return false;
3171	+	if (t.red && tl != null && tl.red && tr != null && tr.red)
3172	+	return false;
3173	+	if (tl != null && !checkInvariants(tl))
3174	+	return false;
3175	+	if (tr != null && !checkInvariants(tr))
3176	+	return false;
3177	+	return true;
3178	+	}
3179	+
3180	+	private static final sun.misc.Unsafe U;
3181	+	private static final long LOCKSTATE;
3182	+	static {
3183	+	try {
3184	+	U = sun.misc.Unsafe.getUnsafe();
3185	+	Class<?> k = TreeBin.class;
3186	+	LOCKSTATE = U.objectFieldOffset
3187	+	(k.getDeclaredField("lockState"));
3188	+	} catch (Exception e) {
3189	+	throw new Error(e);
3190		}
804	–	} finally {
805	–	for (int i = 0; i < segments.length; ++i)
806	–	segments[i].unlock();
3191		}
808	–	return found;
3192		}
3193
3194	+	/* ----------------Table Traversal -------------- */
3195	+
3196		/**
3197	<	* Legacy method testing if some key maps into the specified value
3198	<	* in this table.  This method is identical in functionality to
3199	<	* {@link #containsValue}, and  exists solely to ensure
3200	<	* full compatibility with class {@link java.util.Hashtable},
3201	<	* which supported this method prior to introduction of the
3202	<	* Java Collections framework.
3197	>	* Encapsulates traversal for methods such as containsValue; also
3198	>	* serves as a base class for other iterators and spliterators.
3199	>	*
3200	>	* Method advance visits once each still-valid node that was
3201	>	* reachable upon iterator construction. It might miss some that
3202	>	* were added to a bin after the bin was visited, which is OK wrt
3203	>	* consistency guarantees. Maintaining this property in the face
3204	>	* of possible ongoing resizes requires a fair amount of
3205	>	* bookkeeping state that is difficult to optimize away amidst
3206	>	* volatile accesses.  Even so, traversal maintains reasonable
3207	>	* throughput.
3208	>	*
3209	>	* Normally, iteration proceeds bin-by-bin traversing lists.
3210	>	* However, if the table has been resized, then all future steps
3211	>	* must traverse both the bin at the current index as well as at
3212	>	* (index + baseSize); and so on for further resizings. To
3213	>	* paranoically cope with potential sharing by users of iterators
3214	>	* across threads, iteration terminates if a bounds checks fails
3215	>	* for a table read.
3216	>	*/
3217	>	static class Traverser<K,V> {
3218	>	Node<K,V>[] tab;        // current table; updated if resized
3219	>	Node<K,V> next;         // the next entry to use
3220	>	int index;              // index of bin to use next
3221	>	int baseIndex;          // current index of initial table
3222	>	int baseLimit;          // index bound for initial table
3223	>	final int baseSize;     // initial table size
3224	>
3225	>	Traverser(Node<K,V>[] tab, int size, int index, int limit) {
3226	>	this.tab = tab;
3227	>	this.baseSize = size;
3228	>	this.baseIndex = this.index = index;
3229	>	this.baseLimit = limit;
3230	>	this.next = null;
3231	>	}
3232
3233	<	* @param      value   a value to search for.
3234	<	* @return     <tt>true</tt> if and only if some key maps to the
3235	<	*             <tt>value</tt> argument in this table as
3236	<	*             determined by the <tt>equals</tt> method;
3237	<	*             <tt>false</tt> otherwise.
3238	<	* @throws  NullPointerException  if the value is <tt>null</tt>.
3233	>	/**
3234	>	* Advances if possible, returning next valid node, or null if none.
3235	>	*/
3236	>	final Node<K,V> advance() {
3237	>	Node<K,V> e;
3238	>	if ((e = next) != null)
3239	>	e = e.next;
3240	>	for (;;) {
3241	>	Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
3242	>	if (e != null)
3243	>	return next = e;
3244	>	if (baseIndex >= baseLimit || (t = tab) == null ||
3245	>	(n = t.length) <= (i = index) || i < 0)
3246	>	return next = null;
3247	>	if ((e = tabAt(t, index)) != null && e.hash < 0) {
3248	>	if (e instanceof ForwardingNode) {
3249	>	tab = ((ForwardingNode<K,V>)e).nextTable;
3250	>	e = null;
3251	>	continue;
3252	>	}
3253	>	else if (e instanceof TreeBin)
3254	>	e = ((TreeBin<K,V>)e).first;
3255	>	else
3256	>	e = null;
3257	>	}
3258	>	if ((index += baseSize) >= n)
3259	>	index = ++baseIndex;    // visit upper slots if present
3260	>	}
3261	>	}
3262	>	}
3263	>
3264	>	/**
3265	>	* Base of key, value, and entry Iterators. Adds fields to
3266	>	* Traverser to support iterator.remove.
3267		*/
3268	<	public boolean contains(Object value) {
3269	<	return containsValue(value);
3268	>	static class BaseIterator<K,V> extends Traverser<K,V> {
3269	>	final ConcurrentHashMap<K,V> map;
3270	>	Node<K,V> lastReturned;
3271	>	BaseIterator(Node<K,V>[] tab, int size, int index, int limit,
3272	>	ConcurrentHashMap<K,V> map) {
3273	>	super(tab, size, index, limit);
3274	>	this.map = map;
3275	>	advance();
3276	>	}
3277	>
3278	>	public final boolean hasNext() { return next != null; }
3279	>	public final boolean hasMoreElements() { return next != null; }
3280	>
3281	>	public final void remove() {
3282	>	Node<K,V> p;
3283	>	if ((p = lastReturned) == null)
3284	>	throw new IllegalStateException();
3285	>	lastReturned = null;
3286	>	map.replaceNode(p.key, null, null);
3287	>	}
3288	>	}
3289	>
3290	>	static final class KeyIterator<K,V> extends BaseIterator<K,V>
3291	>	implements Iterator<K>, Enumeration<K> {
3292	>	KeyIterator(Node<K,V>[] tab, int index, int size, int limit,
3293	>	ConcurrentHashMap<K,V> map) {
3294	>	super(tab, index, size, limit, map);
3295	>	}
3296	>
3297	>	public final K next() {
3298	>	Node<K,V> p;
3299	>	if ((p = next) == null)
3300	>	throw new NoSuchElementException();
3301	>	K k = p.key;
3302	>	lastReturned = p;
3303	>	advance();
3304	>	return k;
3305	>	}
3306	>
3307	>	public final K nextElement() { return next(); }
3308	>	}
3309	>
3310	>	static final class ValueIterator<K,V> extends BaseIterator<K,V>
3311	>	implements Iterator<V>, Enumeration<V> {
3312	>	ValueIterator(Node<K,V>[] tab, int index, int size, int limit,
3313	>	ConcurrentHashMap<K,V> map) {
3314	>	super(tab, index, size, limit, map);
3315	>	}
3316	>
3317	>	public final V next() {
3318	>	Node<K,V> p;
3319	>	if ((p = next) == null)
3320	>	throw new NoSuchElementException();
3321	>	V v = p.val;
3322	>	lastReturned = p;
3323	>	advance();
3324	>	return v;
3325	>	}
3326	>
3327	>	public final V nextElement() { return next(); }
3328	>	}
3329	>
3330	>	static final class EntryIterator<K,V> extends BaseIterator<K,V>
3331	>	implements Iterator<Map.Entry<K,V>> {
3332	>	EntryIterator(Node<K,V>[] tab, int index, int size, int limit,
3333	>	ConcurrentHashMap<K,V> map) {
3334	>	super(tab, index, size, limit, map);
3335	>	}
3336	>
3337	>	public final Map.Entry<K,V> next() {
3338	>	Node<K,V> p;
3339	>	if ((p = next) == null)
3340	>	throw new NoSuchElementException();
3341	>	K k = p.key;
3342	>	V v = p.val;
3343	>	lastReturned = p;
3344	>	advance();
3345	>	return new MapEntry<K,V>(k, v, map);
3346	>	}
3347	>	}
3348	>
3349	>	/**
3350	>	* Exported Entry for EntryIterator
3351	>	*/
3352	>	static final class MapEntry<K,V> implements Map.Entry<K,V> {
3353	>	final K key; // non-null
3354	>	V val;       // non-null
3355	>	final ConcurrentHashMap<K,V> map;
3356	>	MapEntry(K key, V val, ConcurrentHashMap<K,V> map) {
3357	>	this.key = key;
3358	>	this.val = val;
3359	>	this.map = map;
3360	>	}
3361	>	public K getKey()        { return key; }
3362	>	public V getValue()      { return val; }
3363	>	public int hashCode()    { return key.hashCode() ^ val.hashCode(); }
3364	>	public String toString() { return key + "=" + val; }
3365	>
3366	>	public boolean equals(Object o) {
3367	>	Object k, v; Map.Entry<?,?> e;
3368	>	return ((o instanceof Map.Entry) &&
3369	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
3370	>	(v = e.getValue()) != null &&
3371	>	(k == key || k.equals(key)) &&
3372	>	(v == val || v.equals(val)));
3373	>	}
3374	>
3375	>	/**
3376	>	* Sets our entry's value and writes through to the map. The
3377	>	* value to return is somewhat arbitrary here. Since we do not
3378	>	* necessarily track asynchronous changes, the most recent
3379	>	* "previous" value could be different from what we return (or
3380	>	* could even have been removed, in which case the put will
3381	>	* re-establish). We do not and cannot guarantee more.
3382	>	*/
3383	>	public V setValue(V value) {
3384	>	if (value == null) throw new NullPointerException();
3385	>	V v = val;
3386	>	val = value;
3387	>	map.put(key, value);
3388	>	return v;
3389	>	}
3390	>	}
3391	>
3392	>	static final class KeySpliterator<K,V> extends Traverser<K,V>
3393	>	implements Spliterator<K> {
3394	>	long est;               // size estimate
3395	>	KeySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3396	>	long est) {
3397	>	super(tab, size, index, limit);
3398	>	this.est = est;
3399	>	}
3400	>
3401	>	public Spliterator<K> trySplit() {
3402	>	int i, f, h;
3403	>	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3404	>	new KeySpliterator<K,V>(tab, baseSize, baseLimit = h,
3405	>	f, est >>>= 1);
3406	>	}
3407	>
3408	>	public void forEachRemaining(Consumer<? super K> action) {
3409	>	if (action == null) throw new NullPointerException();
3410	>	for (Node<K,V> p; (p = advance()) != null;)
3411	>	action.accept(p.key);
3412	>	}
3413	>
3414	>	public boolean tryAdvance(Consumer<? super K> action) {
3415	>	if (action == null) throw new NullPointerException();
3416	>	Node<K,V> p;
3417	>	if ((p = advance()) == null)
3418	>	return false;
3419	>	action.accept(p.key);
3420	>	return true;
3421	>	}
3422	>
3423	>	public long estimateSize() { return est; }
3424	>
3425	>	public int characteristics() {
3426	>	return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3427	>	Spliterator.NONNULL;
3428	>	}
3429	>	}
3430	>
3431	>	static final class ValueSpliterator<K,V> extends Traverser<K,V>
3432	>	implements Spliterator<V> {
3433	>	long est;               // size estimate
3434	>	ValueSpliterator(Node<K,V>[] tab, int size, int index, int limit,
3435	>	long est) {
3436	>	super(tab, size, index, limit);
3437	>	this.est = est;
3438	>	}
3439	>
3440	>	public Spliterator<V> trySplit() {
3441	>	int i, f, h;
3442	>	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3443	>	new ValueSpliterator<K,V>(tab, baseSize, baseLimit = h,
3444	>	f, est >>>= 1);
3445	>	}
3446	>
3447	>	public void forEachRemaining(Consumer<? super V> action) {
3448	>	if (action == null) throw new NullPointerException();
3449	>	for (Node<K,V> p; (p = advance()) != null;)
3450	>	action.accept(p.val);
3451	>	}
3452	>
3453	>	public boolean tryAdvance(Consumer<? super V> action) {
3454	>	if (action == null) throw new NullPointerException();
3455	>	Node<K,V> p;
3456	>	if ((p = advance()) == null)
3457	>	return false;
3458	>	action.accept(p.val);
3459	>	return true;
3460	>	}
3461	>
3462	>	public long estimateSize() { return est; }
3463	>
3464	>	public int characteristics() {
3465	>	return Spliterator.CONCURRENT | Spliterator.NONNULL;
3466	>	}
3467	>	}
3468	>
3469	>	static final class EntrySpliterator<K,V> extends Traverser<K,V>
3470	>	implements Spliterator<Map.Entry<K,V>> {
3471	>	final ConcurrentHashMap<K,V> map; // To export MapEntry
3472	>	long est;               // size estimate
3473	>	EntrySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3474	>	long est, ConcurrentHashMap<K,V> map) {
3475	>	super(tab, size, index, limit);
3476	>	this.map = map;
3477	>	this.est = est;
3478	>	}
3479	>
3480	>	public Spliterator<Map.Entry<K,V>> trySplit() {
3481	>	int i, f, h;
3482	>	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3483	>	new EntrySpliterator<K,V>(tab, baseSize, baseLimit = h,
3484	>	f, est >>>= 1, map);
3485	>	}
3486	>
3487	>	public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
3488	>	if (action == null) throw new NullPointerException();
3489	>	for (Node<K,V> p; (p = advance()) != null; )
3490	>	action.accept(new MapEntry<K,V>(p.key, p.val, map));
3491	>	}
3492	>
3493	>	public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
3494	>	if (action == null) throw new NullPointerException();
3495	>	Node<K,V> p;
3496	>	if ((p = advance()) == null)
3497	>	return false;
3498	>	action.accept(new MapEntry<K,V>(p.key, p.val, map));
3499	>	return true;
3500	>	}
3501	>
3502	>	public long estimateSize() { return est; }
3503	>
3504	>	public int characteristics() {
3505	>	return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3506	>	Spliterator.NONNULL;
3507	>	}
3508	>	}
3509	>
3510	>	// Parallel bulk operations
3511	>
3512	>	/**
3513	>	* Computes initial batch value for bulk tasks. The returned value
3514	>	* is approximately exp2 of the number of times (minus one) to
3515	>	* split task by two before executing leaf action. This value is
3516	>	* faster to compute and more convenient to use as a guide to
3517	>	* splitting than is the depth, since it is used while dividing by
3518	>	* two anyway.
3519	>	*/
3520	>	final int batchFor(long b) {
3521	>	long n;
3522	>	if (b == Long.MAX_VALUE || (n = sumCount()) <= 1L || n < b)
3523	>	return 0;
3524	>	int sp = ForkJoinPool.getCommonPoolParallelism() << 2; // slack of 4
3525	>	return (b <= 0L || (n /= b) >= sp) ? sp : (int)n;
3526		}
3527
3528		/**
3529	<	* Maps the specified <tt>key</tt> to the specified
832	<	* <tt>value</tt> in this table. Neither the key nor the
833	<	* value can be <tt>null</tt>.
3529	>	* Performs the given action for each (key, value).
3530		*
3531	<	* <p> The value can be retrieved by calling the <tt>get</tt> method
3532	<	* with a key that is equal to the original key.
3531	>	* @param parallelismThreshold the (estimated) number of elements
3532	>	* needed for this operation to be executed in parallel
3533	>	* @param action the action
3534	>	* @since 1.8
3535	>	*/
3536	>	public void forEach(long parallelismThreshold,
3537	>	BiConsumer<? super K,? super V> action) {
3538	>	if (action == null) throw new NullPointerException();
3539	>	new ForEachMappingTask<K,V>
3540	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3541	>	action).invoke();
3542	>	}
3543	>
3544	>	/**
3545	>	* Performs the given action for each non-null transformation
3546	>	* of each (key, value).
3547		*
3548	<	* @param      key     the table key.
3549	<	* @param      value   the value.
3550	<	* @return     the previous value of the specified key in this table,
3551	<	*             or <tt>null</tt> if it did not have one.
3552	<	* @throws  NullPointerException  if the key or value is
3553	<	*               <tt>null</tt>.
3548	>	* @param parallelismThreshold the (estimated) number of elements
3549	>	* needed for this operation to be executed in parallel
3550	>	* @param transformer a function returning the transformation
3551	>	* for an element, or null if there is no transformation (in
3552	>	* which case the action is not applied)
3553	>	* @param action the action
3554	>	* @param <U> the return type of the transformer
3555	>	* @since 1.8
3556		*/
3557	<	public V put(K key, V value) {
3558	<	if (value == null)
3557	>	public <U> void forEach(long parallelismThreshold,
3558	>	BiFunction<? super K, ? super V, ? extends U> transformer,
3559	>	Consumer<? super U> action) {
3560	>	if (transformer == null || action == null)
3561		throw new NullPointerException();
3562	<	int hash = hash(key);
3563	<	return segmentFor(hash).put(key, hash, value, false);
3562	>	new ForEachTransformedMappingTask<K,V,U>
3563	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3564	>	transformer, action).invoke();
3565		}
3566
3567		/**
3568	<	* If the specified key is not already associated
3569	<	* with a value, associate it with the given value.
3570	<	* This is equivalent to
3571	<	* <pre>
3572	<	*   if (!map.containsKey(key))
3573	<	*      return map.put(key, value);
3574	<	*   else
3575	<	*      return map.get(key);
3576	<	* </pre>
3577	<	* Except that the action is performed atomically.
3578	<	* @param key key with which the specified value is to be associated.
3579	<	* @param value value to be associated with the specified key.
3580	<	* @return previous value associated with specified key, or <tt>null</tt>
3581	<	*         if there was no mapping for key.
867	<	* @throws NullPointerException if the specified key or value is
868	<	*            <tt>null</tt>.
3568	>	* Returns a non-null result from applying the given search
3569	>	* function on each (key, value), or null if none.  Upon
3570	>	* success, further element processing is suppressed and the
3571	>	* results of any other parallel invocations of the search
3572	>	* function are ignored.
3573	>	*
3574	>	* @param parallelismThreshold the (estimated) number of elements
3575	>	* needed for this operation to be executed in parallel
3576	>	* @param searchFunction a function returning a non-null
3577	>	* result on success, else null
3578	>	* @param <U> the return type of the search function
3579	>	* @return a non-null result from applying the given search
3580	>	* function on each (key, value), or null if none
3581	>	* @since 1.8
3582		*/
3583	<	public V putIfAbsent(K key, V value) {
3584	<	if (value == null)
3583	>	public <U> U search(long parallelismThreshold,
3584	>	BiFunction<? super K, ? super V, ? extends U> searchFunction) {
3585	>	if (searchFunction == null) throw new NullPointerException();
3586	>	return new SearchMappingsTask<K,V,U>
3587	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3588	>	searchFunction, new AtomicReference<U>()).invoke();
3589	>	}
3590	>
3591	>	/**
3592	>	* Returns the result of accumulating the given transformation
3593	>	* of all (key, value) pairs using the given reducer to
3594	>	* combine values, or null if none.
3595	>	*
3596	>	* @param parallelismThreshold the (estimated) number of elements
3597	>	* needed for this operation to be executed in parallel
3598	>	* @param transformer a function returning the transformation
3599	>	* for an element, or null if there is no transformation (in
3600	>	* which case it is not combined)
3601	>	* @param reducer a commutative associative combining function
3602	>	* @param <U> the return type of the transformer
3603	>	* @return the result of accumulating the given transformation
3604	>	* of all (key, value) pairs
3605	>	* @since 1.8
3606	>	*/
3607	>	public <U> U reduce(long parallelismThreshold,
3608	>	BiFunction<? super K, ? super V, ? extends U> transformer,
3609	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3610	>	if (transformer == null || reducer == null)
3611		throw new NullPointerException();
3612	<	int hash = hash(key);
3613	<	return segmentFor(hash).put(key, hash, value, true);
3612	>	return new MapReduceMappingsTask<K,V,U>
3613	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3614	>	null, transformer, reducer).invoke();
3615		}
3616
3617	+	/**
3618	+	* Returns the result of accumulating the given transformation
3619	+	* of all (key, value) pairs using the given reducer to
3620	+	* combine values, and the given basis as an identity value.
3621	+	*
3622	+	* @param parallelismThreshold the (estimated) number of elements
3623	+	* needed for this operation to be executed in parallel
3624	+	* @param transformer a function returning the transformation
3625	+	* for an element
3626	+	* @param basis the identity (initial default value) for the reduction
3627	+	* @param reducer a commutative associative combining function
3628	+	* @return the result of accumulating the given transformation
3629	+	* of all (key, value) pairs
3630	+	* @since 1.8
3631	+	*/
3632	+	public double reduceToDouble(long parallelismThreshold,
3633	+	ToDoubleBiFunction<? super K, ? super V> transformer,
3634	+	double basis,
3635	+	DoubleBinaryOperator reducer) {
3636	+	if (transformer == null || reducer == null)
3637	+	throw new NullPointerException();
3638	+	return new MapReduceMappingsToDoubleTask<K,V>
3639	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3640	+	null, transformer, basis, reducer).invoke();
3641	+	}
3642
3643		/**
3644	<	* Copies all of the mappings from the specified map to this one.
3644	>	* Returns the result of accumulating the given transformation
3645	>	* of all (key, value) pairs using the given reducer to
3646	>	* combine values, and the given basis as an identity value.
3647		*
3648	<	* These mappings replace any mappings that this map had for any of the
3649	<	* keys currently in the specified Map.
3648	>	* @param parallelismThreshold the (estimated) number of elements
3649	>	* needed for this operation to be executed in parallel
3650	>	* @param transformer a function returning the transformation
3651	>	* for an element
3652	>	* @param basis the identity (initial default value) for the reduction
3653	>	* @param reducer a commutative associative combining function
3654	>	* @return the result of accumulating the given transformation
3655	>	* of all (key, value) pairs
3656	>	* @since 1.8
3657	>	*/
3658	>	public long reduceToLong(long parallelismThreshold,
3659	>	ToLongBiFunction<? super K, ? super V> transformer,
3660	>	long basis,
3661	>	LongBinaryOperator reducer) {
3662	>	if (transformer == null || reducer == null)
3663	>	throw new NullPointerException();
3664	>	return new MapReduceMappingsToLongTask<K,V>
3665	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3666	>	null, transformer, basis, reducer).invoke();
3667	>	}
3668	>
3669	>	/**
3670	>	* Returns the result of accumulating the given transformation
3671	>	* of all (key, value) pairs using the given reducer to
3672	>	* combine values, and the given basis as an identity value.
3673		*
3674	<	* @param t Mappings to be stored in this map.
3674	>	* @param parallelismThreshold the (estimated) number of elements
3675	>	* needed for this operation to be executed in parallel
3676	>	* @param transformer a function returning the transformation
3677	>	* for an element
3678	>	* @param basis the identity (initial default value) for the reduction
3679	>	* @param reducer a commutative associative combining function
3680	>	* @return the result of accumulating the given transformation
3681	>	* of all (key, value) pairs
3682	>	* @since 1.8
3683		*/
3684	<	public void putAll(Map<? extends K, ? extends V> t) {
3685	<	for (Iterator<? extends Map.Entry<? extends K, ? extends V>> it = (Iterator<? extends Map.Entry<? extends K, ? extends V>>) t.entrySet().iterator(); it.hasNext(); ) {
3686	<	Entry<? extends K, ? extends V> e = it.next();
3687	<	put(e.getKey(), e.getValue());
3688	<	}
3684	>	public int reduceToInt(long parallelismThreshold,
3685	>	ToIntBiFunction<? super K, ? super V> transformer,
3686	>	int basis,
3687	>	IntBinaryOperator reducer) {
3688	>	if (transformer == null || reducer == null)
3689	>	throw new NullPointerException();
3690	>	return new MapReduceMappingsToIntTask<K,V>
3691	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3692	>	null, transformer, basis, reducer).invoke();
3693		}
3694
3695		/**
3696	<	* Removes the key (and its corresponding value) from this
895	<	* table. This method does nothing if the key is not in the table.
3696	>	* Performs the given action for each key.
3697		*
3698	<	* @param   key   the key that needs to be removed.
3699	<	* @return  the value to which the key had been mapped in this table,
3700	<	*          or <tt>null</tt> if the key did not have a mapping.
3701	<	* @throws  NullPointerException  if the key is
901	<	*               <tt>null</tt>.
3698	>	* @param parallelismThreshold the (estimated) number of elements
3699	>	* needed for this operation to be executed in parallel
3700	>	* @param action the action
3701	>	* @since 1.8
3702		*/
3703	<	public V remove(Object key) {
3704	<	int hash = hash(key);
3705	<	return segmentFor(hash).remove(key, hash, null);
3703	>	public void forEachKey(long parallelismThreshold,
3704	>	Consumer<? super K> action) {
3705	>	if (action == null) throw new NullPointerException();
3706	>	new ForEachKeyTask<K,V>
3707	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3708	>	action).invoke();
3709		}
3710
3711		/**
3712	<	* Remove entry for key only if currently mapped to given value.
3713	<	* Acts as
3714	<	* <pre>
3715	<	*  if (map.get(key).equals(value)) {
3716	<	*     map.remove(key);
3717	<	*     return true;
3718	<	* } else return false;
3719	<	* </pre>
3720	<	* except that the action is performed atomically.
3721	<	* @param key key with which the specified value is associated.
3722	<	* @param value value associated with the specified key.
920	<	* @return true if the value was removed
921	<	* @throws NullPointerException if the specified key is
922	<	*            <tt>null</tt>.
3712	>	* Performs the given action for each non-null transformation
3713	>	* of each key.
3714	>	*
3715	>	* @param parallelismThreshold the (estimated) number of elements
3716	>	* needed for this operation to be executed in parallel
3717	>	* @param transformer a function returning the transformation
3718	>	* for an element, or null if there is no transformation (in
3719	>	* which case the action is not applied)
3720	>	* @param action the action
3721	>	* @param <U> the return type of the transformer
3722	>	* @since 1.8
3723		*/
3724	<	public boolean remove(Object key, Object value) {
3725	<	int hash = hash(key);
3726	<	return segmentFor(hash).remove(key, hash, value) != null;
3724	>	public <U> void forEachKey(long parallelismThreshold,
3725	>	Function<? super K, ? extends U> transformer,
3726	>	Consumer<? super U> action) {
3727	>	if (transformer == null || action == null)
3728	>	throw new NullPointerException();
3729	>	new ForEachTransformedKeyTask<K,V,U>
3730	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3731	>	transformer, action).invoke();
3732		}
3733
3734	+	/**
3735	+	* Returns a non-null result from applying the given search
3736	+	* function on each key, or null if none. Upon success,
3737	+	* further element processing is suppressed and the results of
3738	+	* any other parallel invocations of the search function are
3739	+	* ignored.
3740	+	*
3741	+	* @param parallelismThreshold the (estimated) number of elements
3742	+	* needed for this operation to be executed in parallel
3743	+	* @param searchFunction a function returning a non-null
3744	+	* result on success, else null
3745	+	* @param <U> the return type of the search function
3746	+	* @return a non-null result from applying the given search
3747	+	* function on each key, or null if none
3748	+	* @since 1.8
3749	+	*/
3750	+	public <U> U searchKeys(long parallelismThreshold,
3751	+	Function<? super K, ? extends U> searchFunction) {
3752	+	if (searchFunction == null) throw new NullPointerException();
3753	+	return new SearchKeysTask<K,V,U>
3754	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3755	+	searchFunction, new AtomicReference<U>()).invoke();
3756	+	}
3757
3758		/**
3759	<	* Replace entry for key only if currently mapped to given value.
3760	<	* Acts as
3761	<	* <pre>
3762	<	*  if (map.get(key).equals(oldValue)) {
3763	<	*     map.put(key, newValue);
3764	<	*     return true;
3765	<	* } else return false;
3766	<	* </pre>
3767	<	* except that the action is performed atomically.
940	<	* @param key key with which the specified value is associated.
941	<	* @param oldValue value expected to be associated with the specified key.
942	<	* @param newValue value to be associated with the specified key.
943	<	* @return true if the value was replaced
944	<	* @throws NullPointerException if the specified key or values are
945	<	* <tt>null</tt>.
3759	>	* Returns the result of accumulating all keys using the given
3760	>	* reducer to combine values, or null if none.
3761	>	*
3762	>	* @param parallelismThreshold the (estimated) number of elements
3763	>	* needed for this operation to be executed in parallel
3764	>	* @param reducer a commutative associative combining function
3765	>	* @return the result of accumulating all keys using the given
3766	>	* reducer to combine values, or null if none
3767	>	* @since 1.8
3768		*/
3769	<	public boolean replace(K key, V oldValue, V newValue) {
3770	<	if (oldValue == null || newValue == null)
3769	>	public K reduceKeys(long parallelismThreshold,
3770	>	BiFunction<? super K, ? super K, ? extends K> reducer) {
3771	>	if (reducer == null) throw new NullPointerException();
3772	>	return new ReduceKeysTask<K,V>
3773	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3774	>	null, reducer).invoke();
3775	>	}
3776	>
3777	>	/**
3778	>	* Returns the result of accumulating the given transformation
3779	>	* of all keys using the given reducer to combine values, or
3780	>	* null if none.
3781	>	*
3782	>	* @param parallelismThreshold the (estimated) number of elements
3783	>	* needed for this operation to be executed in parallel
3784	>	* @param transformer a function returning the transformation
3785	>	* for an element, or null if there is no transformation (in
3786	>	* which case it is not combined)
3787	>	* @param reducer a commutative associative combining function
3788	>	* @param <U> the return type of the transformer
3789	>	* @return the result of accumulating the given transformation
3790	>	* of all keys
3791	>	* @since 1.8
3792	>	*/
3793	>	public <U> U reduceKeys(long parallelismThreshold,
3794	>	Function<? super K, ? extends U> transformer,
3795	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3796	>	if (transformer == null || reducer == null)
3797		throw new NullPointerException();
3798	<	int hash = hash(key);
3799	<	return segmentFor(hash).replace(key, hash, oldValue, newValue);
3798	>	return new MapReduceKeysTask<K,V,U>
3799	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3800	>	null, transformer, reducer).invoke();
3801		}
3802
3803		/**
3804	<	* Replace entry for key only if currently mapped to some value.
3805	<	* Acts as
3806	<	* <pre>
3807	<	*  if ((map.containsKey(key)) {
3808	<	*     return map.put(key, value);
3809	<	* } else return null;
3810	<	* </pre>
3811	<	* except that the action is performed atomically.
3812	<	* @param key key with which the specified value is associated.
3813	<	* @param value value to be associated with the specified key.
3814	<	* @return previous value associated with specified key, or <tt>null</tt>
3815	<	*         if there was no mapping for key.
3816	<	* @throws NullPointerException if the specified key or value is
968	<	*            <tt>null</tt>.
3804	>	* Returns the result of accumulating the given transformation
3805	>	* of all keys using the given reducer to combine values, and
3806	>	* the given basis as an identity value.
3807	>	*
3808	>	* @param parallelismThreshold the (estimated) number of elements
3809	>	* needed for this operation to be executed in parallel
3810	>	* @param transformer a function returning the transformation
3811	>	* for an element
3812	>	* @param basis the identity (initial default value) for the reduction
3813	>	* @param reducer a commutative associative combining function
3814	>	* @return the result of accumulating the given transformation
3815	>	* of all keys
3816	>	* @since 1.8
3817		*/
3818	<	public V replace(K key, V value) {
3819	<	if (value == null)
3818	>	public double reduceKeysToDouble(long parallelismThreshold,
3819	>	ToDoubleFunction<? super K> transformer,
3820	>	double basis,
3821	>	DoubleBinaryOperator reducer) {
3822	>	if (transformer == null || reducer == null)
3823		throw new NullPointerException();
3824	<	int hash = hash(key);
3825	<	return segmentFor(hash).replace(key, hash, value);
3824	>	return new MapReduceKeysToDoubleTask<K,V>
3825	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3826	>	null, transformer, basis, reducer).invoke();
3827		}
3828
3829	+	/**
3830	+	* Returns the result of accumulating the given transformation
3831	+	* of all keys using the given reducer to combine values, and
3832	+	* the given basis as an identity value.
3833	+	*
3834	+	* @param parallelismThreshold the (estimated) number of elements
3835	+	* needed for this operation to be executed in parallel
3836	+	* @param transformer a function returning the transformation
3837	+	* for an element
3838	+	* @param basis the identity (initial default value) for the reduction
3839	+	* @param reducer a commutative associative combining function
3840	+	* @return the result of accumulating the given transformation
3841	+	* of all keys
3842	+	* @since 1.8
3843	+	*/
3844	+	public long reduceKeysToLong(long parallelismThreshold,
3845	+	ToLongFunction<? super K> transformer,
3846	+	long basis,
3847	+	LongBinaryOperator reducer) {
3848	+	if (transformer == null || reducer == null)
3849	+	throw new NullPointerException();
3850	+	return new MapReduceKeysToLongTask<K,V>
3851	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3852	+	null, transformer, basis, reducer).invoke();
3853	+	}
3854
3855		/**
3856	<	* Removes all mappings from this map.
3856	>	* Returns the result of accumulating the given transformation
3857	>	* of all keys using the given reducer to combine values, and
3858	>	* the given basis as an identity value.
3859	>	*
3860	>	* @param parallelismThreshold the (estimated) number of elements
3861	>	* needed for this operation to be executed in parallel
3862	>	* @param transformer a function returning the transformation
3863	>	* for an element
3864	>	* @param basis the identity (initial default value) for the reduction
3865	>	* @param reducer a commutative associative combining function
3866	>	* @return the result of accumulating the given transformation
3867	>	* of all keys
3868	>	* @since 1.8
3869		*/
3870	<	public void clear() {
3871	<	for (int i = 0; i < segments.length; ++i)
3872	<	segments[i].clear();
3870	>	public int reduceKeysToInt(long parallelismThreshold,
3871	>	ToIntFunction<? super K> transformer,
3872	>	int basis,
3873	>	IntBinaryOperator reducer) {
3874	>	if (transformer == null || reducer == null)
3875	>	throw new NullPointerException();
3876	>	return new MapReduceKeysToIntTask<K,V>
3877	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3878	>	null, transformer, basis, reducer).invoke();
3879		}
3880
3881		/**
3882	<	* Returns a set view of the keys contained in this map.  The set is
3883	<	* backed by the map, so changes to the map are reflected in the set, and
3884	<	* vice-versa.  The set supports element removal, which removes the
3885	<	* corresponding mapping from this map, via the <tt>Iterator.remove</tt>,
3886	<	* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and
3887	<	* <tt>clear</tt> operations.  It does not support the <tt>add</tt> or
3888	<	* <tt>addAll</tt> operations.
3889	<	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
3890	<	* will never throw {@link java.util.ConcurrentModificationException},
3891	<	* and guarantees to traverse elements as they existed upon
3892	<	* construction of the iterator, and may (but is not guaranteed to)
3893	<	* reflect any modifications subsequent to construction.
3894	<	*
3895	<	* @return a set view of the keys contained in this map.
1001	<	*/
1002	<	public Set<K> keySet() {
1003	<	Set<K> ks = keySet;
1004	<	return (ks != null) ? ks : (keySet = new KeySet());
3882	>	* Performs the given action for each value.
3883	>	*
3884	>	* @param parallelismThreshold the (estimated) number of elements
3885	>	* needed for this operation to be executed in parallel
3886	>	* @param action the action
3887	>	* @since 1.8
3888	>	*/
3889	>	public void forEachValue(long parallelismThreshold,
3890	>	Consumer<? super V> action) {
3891	>	if (action == null)
3892	>	throw new NullPointerException();
3893	>	new ForEachValueTask<K,V>
3894	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3895	>	action).invoke();
3896		}
3897
3898	+	/**
3899	+	* Performs the given action for each non-null transformation
3900	+	* of each value.
3901	+	*
3902	+	* @param parallelismThreshold the (estimated) number of elements
3903	+	* needed for this operation to be executed in parallel
3904	+	* @param transformer a function returning the transformation
3905	+	* for an element, or null if there is no transformation (in
3906	+	* which case the action is not applied)
3907	+	* @param action the action
3908	+	* @param <U> the return type of the transformer
3909	+	* @since 1.8
3910	+	*/
3911	+	public <U> void forEachValue(long parallelismThreshold,
3912	+	Function<? super V, ? extends U> transformer,
3913	+	Consumer<? super U> action) {
3914	+	if (transformer == null || action == null)
3915	+	throw new NullPointerException();
3916	+	new ForEachTransformedValueTask<K,V,U>
3917	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3918	+	transformer, action).invoke();
3919	+	}
3920
3921		/**
3922	<	* Returns a collection view of the values contained in this map.  The
3923	<	* collection is backed by the map, so changes to the map are reflected in
3924	<	* the collection, and vice-versa.  The collection supports element
3925	<	* removal, which removes the corresponding mapping from this map, via the
3926	<	* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
1014	<	* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
1015	<	* It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
1016	<	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
1017	<	* will never throw {@link java.util.ConcurrentModificationException},
1018	<	* and guarantees to traverse elements as they existed upon
1019	<	* construction of the iterator, and may (but is not guaranteed to)
1020	<	* reflect any modifications subsequent to construction.
3922	>	* Returns a non-null result from applying the given search
3923	>	* function on each value, or null if none.  Upon success,
3924	>	* further element processing is suppressed and the results of
3925	>	* any other parallel invocations of the search function are
3926	>	* ignored.
3927		*
3928	<	* @return a collection view of the values contained in this map.
3928	>	* @param parallelismThreshold the (estimated) number of elements
3929	>	* needed for this operation to be executed in parallel
3930	>	* @param searchFunction a function returning a non-null
3931	>	* result on success, else null
3932	>	* @param <U> the return type of the search function
3933	>	* @return a non-null result from applying the given search
3934	>	* function on each value, or null if none
3935	>	* @since 1.8
3936		*/
3937	<	public Collection<V> values() {
3938	<	Collection<V> vs = values;
3939	<	return (vs != null) ? vs : (values = new Values());
3937	>	public <U> U searchValues(long parallelismThreshold,
3938	>	Function<? super V, ? extends U> searchFunction) {
3939	>	if (searchFunction == null) throw new NullPointerException();
3940	>	return new SearchValuesTask<K,V,U>
3941	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3942	>	searchFunction, new AtomicReference<U>()).invoke();
3943		}
3944
3945	+	/**
3946	+	* Returns the result of accumulating all values using the
3947	+	* given reducer to combine values, or null if none.
3948	+	*
3949	+	* @param parallelismThreshold the (estimated) number of elements
3950	+	* needed for this operation to be executed in parallel
3951	+	* @param reducer a commutative associative combining function
3952	+	* @return the result of accumulating all values
3953	+	* @since 1.8
3954	+	*/
3955	+	public V reduceValues(long parallelismThreshold,
3956	+	BiFunction<? super V, ? super V, ? extends V> reducer) {
3957	+	if (reducer == null) throw new NullPointerException();
3958	+	return new ReduceValuesTask<K,V>
3959	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3960	+	null, reducer).invoke();
3961	+	}
3962
3963		/**
3964	<	* Returns a collection view of the mappings contained in this map.  Each
3965	<	* element in the returned collection is a <tt>Map.Entry</tt>.  The
3966	<	* collection is backed by the map, so changes to the map are reflected in
1034	<	* the collection, and vice-versa.  The collection supports element
1035	<	* removal, which removes the corresponding mapping from the map, via the
1036	<	* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
1037	<	* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
1038	<	* It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
1039	<	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
1040	<	* will never throw {@link java.util.ConcurrentModificationException},
1041	<	* and guarantees to traverse elements as they existed upon
1042	<	* construction of the iterator, and may (but is not guaranteed to)
1043	<	* reflect any modifications subsequent to construction.
3964	>	* Returns the result of accumulating the given transformation
3965	>	* of all values using the given reducer to combine values, or
3966	>	* null if none.
3967		*
3968	<	* @return a collection view of the mappings contained in this map.
3968	>	* @param parallelismThreshold the (estimated) number of elements
3969	>	* needed for this operation to be executed in parallel
3970	>	* @param transformer a function returning the transformation
3971	>	* for an element, or null if there is no transformation (in
3972	>	* which case it is not combined)
3973	>	* @param reducer a commutative associative combining function
3974	>	* @param <U> the return type of the transformer
3975	>	* @return the result of accumulating the given transformation
3976	>	* of all values
3977	>	* @since 1.8
3978		*/
3979	<	public Set<Map.Entry<K,V>> entrySet() {
3980	<	Set<Map.Entry<K,V>> es = entrySet;
3981	<	return (es != null) ? es : (entrySet = (Set<Map.Entry<K,V>>) (Set) new EntrySet());
3979	>	public <U> U reduceValues(long parallelismThreshold,
3980	>	Function<? super V, ? extends U> transformer,
3981	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3982	>	if (transformer == null || reducer == null)
3983	>	throw new NullPointerException();
3984	>	return new MapReduceValuesTask<K,V,U>
3985	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3986	>	null, transformer, reducer).invoke();
3987		}
3988
3989	+	/**
3990	+	* Returns the result of accumulating the given transformation
3991	+	* of all values using the given reducer to combine values,
3992	+	* and the given basis as an identity value.
3993	+	*
3994	+	* @param parallelismThreshold the (estimated) number of elements
3995	+	* needed for this operation to be executed in parallel
3996	+	* @param transformer a function returning the transformation
3997	+	* for an element
3998	+	* @param basis the identity (initial default value) for the reduction
3999	+	* @param reducer a commutative associative combining function
4000	+	* @return the result of accumulating the given transformation
4001	+	* of all values
4002	+	* @since 1.8
4003	+	*/
4004	+	public double reduceValuesToDouble(long parallelismThreshold,
4005	+	ToDoubleFunction<? super V> transformer,
4006	+	double basis,
4007	+	DoubleBinaryOperator reducer) {
4008	+	if (transformer == null || reducer == null)
4009	+	throw new NullPointerException();
4010	+	return new MapReduceValuesToDoubleTask<K,V>
4011	+	(null, batchFor(parallelismThreshold), 0, 0, table,
4012	+	null, transformer, basis, reducer).invoke();
4013	+	}
4014
4015		/**
4016	<	* Returns an enumeration of the keys in this table.
4016	>	* Returns the result of accumulating the given transformation
4017	>	* of all values using the given reducer to combine values,
4018	>	* and the given basis as an identity value.
4019		*
4020	<	* @return  an enumeration of the keys in this table.
4021	<	* @see     #keySet
4020	>	* @param parallelismThreshold the (estimated) number of elements
4021	>	* needed for this operation to be executed in parallel
4022	>	* @param transformer a function returning the transformation
4023	>	* for an element
4024	>	* @param basis the identity (initial default value) for the reduction
4025	>	* @param reducer a commutative associative combining function
4026	>	* @return the result of accumulating the given transformation
4027	>	* of all values
4028	>	* @since 1.8
4029		*/
4030	<	public Enumeration<K> keys() {
4031	<	return new KeyIterator();
4030	>	public long reduceValuesToLong(long parallelismThreshold,
4031	>	ToLongFunction<? super V> transformer,
4032	>	long basis,
4033	>	LongBinaryOperator reducer) {
4034	>	if (transformer == null || reducer == null)
4035	>	throw new NullPointerException();
4036	>	return new MapReduceValuesToLongTask<K,V>
4037	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4038	>	null, transformer, basis, reducer).invoke();
4039		}
4040
4041		/**
4042	<	* Returns an enumeration of the values in this table.
4042	>	* Returns the result of accumulating the given transformation
4043	>	* of all values using the given reducer to combine values,
4044	>	* and the given basis as an identity value.
4045		*
4046	<	* @return  an enumeration of the values in this table.
4047	<	* @see     #values
4046	>	* @param parallelismThreshold the (estimated) number of elements
4047	>	* needed for this operation to be executed in parallel
4048	>	* @param transformer a function returning the transformation
4049	>	* for an element
4050	>	* @param basis the identity (initial default value) for the reduction
4051	>	* @param reducer a commutative associative combining function
4052	>	* @return the result of accumulating the given transformation
4053	>	* of all values
4054	>	* @since 1.8
4055		*/
4056	<	public Enumeration<V> elements() {
4057	<	return new ValueIterator();
4056	>	public int reduceValuesToInt(long parallelismThreshold,
4057	>	ToIntFunction<? super V> transformer,
4058	>	int basis,
4059	>	IntBinaryOperator reducer) {
4060	>	if (transformer == null || reducer == null)
4061	>	throw new NullPointerException();
4062	>	return new MapReduceValuesToIntTask<K,V>
4063	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4064	>	null, transformer, basis, reducer).invoke();
4065		}
4066
4067	<	/* ---------------- Iterator Support -------------- */
4067	>	/**
4068	>	* Performs the given action for each entry.
4069	>	*
4070	>	* @param parallelismThreshold the (estimated) number of elements
4071	>	* needed for this operation to be executed in parallel
4072	>	* @param action the action
4073	>	* @since 1.8
4074	>	*/
4075	>	public void forEachEntry(long parallelismThreshold,
4076	>	Consumer<? super Map.Entry<K,V>> action) {
4077	>	if (action == null) throw new NullPointerException();
4078	>	new ForEachEntryTask<K,V>(null, batchFor(parallelismThreshold), 0, 0, table,
4079	>	action).invoke();
4080	>	}
4081
4082	<	abstract class HashIterator {
4083	<	int nextSegmentIndex;
4084	<	int nextTableIndex;
4085	<	HashEntry[] currentTable;
4086	<	HashEntry<K, V> nextEntry;
4087	<	HashEntry<K, V> lastReturned;
4082	>	/**
4083	>	* Performs the given action for each non-null transformation
4084	>	* of each entry.
4085	>	*
4086	>	* @param parallelismThreshold the (estimated) number of elements
4087	>	* needed for this operation to be executed in parallel
4088	>	* @param transformer a function returning the transformation
4089	>	* for an element, or null if there is no transformation (in
4090	>	* which case the action is not applied)
4091	>	* @param action the action
4092	>	* @param <U> the return type of the transformer
4093	>	* @since 1.8
4094	>	*/
4095	>	public <U> void forEachEntry(long parallelismThreshold,
4096	>	Function<Map.Entry<K,V>, ? extends U> transformer,
4097	>	Consumer<? super U> action) {
4098	>	if (transformer == null || action == null)
4099	>	throw new NullPointerException();
4100	>	new ForEachTransformedEntryTask<K,V,U>
4101	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4102	>	transformer, action).invoke();
4103	>	}
4104
4105	<	HashIterator() {
4106	<	nextSegmentIndex = segments.length - 1;
4107	<	nextTableIndex = -1;
4108	<	advance();
4109	<	}
4105	>	/**
4106	>	* Returns a non-null result from applying the given search
4107	>	* function on each entry, or null if none.  Upon success,
4108	>	* further element processing is suppressed and the results of
4109	>	* any other parallel invocations of the search function are
4110	>	* ignored.
4111	>	*
4112	>	* @param parallelismThreshold the (estimated) number of elements
4113	>	* needed for this operation to be executed in parallel
4114	>	* @param searchFunction a function returning a non-null
4115	>	* result on success, else null
4116	>	* @param <U> the return type of the search function
4117	>	* @return a non-null result from applying the given search
4118	>	* function on each entry, or null if none
4119	>	* @since 1.8
4120	>	*/
4121	>	public <U> U searchEntries(long parallelismThreshold,
4122	>	Function<Map.Entry<K,V>, ? extends U> searchFunction) {
4123	>	if (searchFunction == null) throw new NullPointerException();
4124	>	return new SearchEntriesTask<K,V,U>
4125	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4126	>	searchFunction, new AtomicReference<U>()).invoke();
4127	>	}
4128
4129	<	public boolean hasMoreElements() { return hasNext(); }
4129	>	/**
4130	>	* Returns the result of accumulating all entries using the
4131	>	* given reducer to combine values, or null if none.
4132	>	*
4133	>	* @param parallelismThreshold the (estimated) number of elements
4134	>	* needed for this operation to be executed in parallel
4135	>	* @param reducer a commutative associative combining function
4136	>	* @return the result of accumulating all entries
4137	>	* @since 1.8
4138	>	*/
4139	>	public Map.Entry<K,V> reduceEntries(long parallelismThreshold,
4140	>	BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4141	>	if (reducer == null) throw new NullPointerException();
4142	>	return new ReduceEntriesTask<K,V>
4143	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4144	>	null, reducer).invoke();
4145	>	}
4146
4147	<	final void advance() {
4148	<	if (nextEntry != null && (nextEntry = nextEntry.next) != null)
4149	<	return;
4147	>	/**
4148	>	* Returns the result of accumulating the given transformation
4149	>	* of all entries using the given reducer to combine values,
4150	>	* or null if none.
4151	>	*
4152	>	* @param parallelismThreshold the (estimated) number of elements
4153	>	* needed for this operation to be executed in parallel
4154	>	* @param transformer a function returning the transformation
4155	>	* for an element, or null if there is no transformation (in
4156	>	* which case it is not combined)
4157	>	* @param reducer a commutative associative combining function
4158	>	* @param <U> the return type of the transformer
4159	>	* @return the result of accumulating the given transformation
4160	>	* of all entries
4161	>	* @since 1.8
4162	>	*/
4163	>	public <U> U reduceEntries(long parallelismThreshold,
4164	>	Function<Map.Entry<K,V>, ? extends U> transformer,
4165	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
4166	>	if (transformer == null || reducer == null)
4167	>	throw new NullPointerException();
4168	>	return new MapReduceEntriesTask<K,V,U>
4169	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4170	>	null, transformer, reducer).invoke();
4171	>	}
4172
4173	<	while (nextTableIndex >= 0) {
4174	<	if ( (nextEntry = (HashEntry<K,V>)currentTable[nextTableIndex--]) != null)
4175	<	return;
4173	>	/**
4174	>	* Returns the result of accumulating the given transformation
4175	>	* of all entries using the given reducer to combine values,
4176	>	* and the given basis as an identity value.
4177	>	*
4178	>	* @param parallelismThreshold the (estimated) number of elements
4179	>	* needed for this operation to be executed in parallel
4180	>	* @param transformer a function returning the transformation
4181	>	* for an element
4182	>	* @param basis the identity (initial default value) for the reduction
4183	>	* @param reducer a commutative associative combining function
4184	>	* @return the result of accumulating the given transformation
4185	>	* of all entries
4186	>	* @since 1.8
4187	>	*/
4188	>	public double reduceEntriesToDouble(long parallelismThreshold,
4189	>	ToDoubleFunction<Map.Entry<K,V>> transformer,
4190	>	double basis,
4191	>	DoubleBinaryOperator reducer) {
4192	>	if (transformer == null || reducer == null)
4193	>	throw new NullPointerException();
4194	>	return new MapReduceEntriesToDoubleTask<K,V>
4195	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4196	>	null, transformer, basis, reducer).invoke();
4197	>	}
4198	>
4199	>	/**
4200	>	* Returns the result of accumulating the given transformation
4201	>	* of all entries using the given reducer to combine values,
4202	>	* and the given basis as an identity value.
4203	>	*
4204	>	* @param parallelismThreshold the (estimated) number of elements
4205	>	* needed for this operation to be executed in parallel
4206	>	* @param transformer a function returning the transformation
4207	>	* for an element
4208	>	* @param basis the identity (initial default value) for the reduction
4209	>	* @param reducer a commutative associative combining function
4210	>	* @return the result of accumulating the given transformation
4211	>	* of all entries
4212	>	* @since 1.8
4213	>	*/
4214	>	public long reduceEntriesToLong(long parallelismThreshold,
4215	>	ToLongFunction<Map.Entry<K,V>> transformer,
4216	>	long basis,
4217	>	LongBinaryOperator reducer) {
4218	>	if (transformer == null || reducer == null)
4219	>	throw new NullPointerException();
4220	>	return new MapReduceEntriesToLongTask<K,V>
4221	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4222	>	null, transformer, basis, reducer).invoke();
4223	>	}
4224	>
4225	>	/**
4226	>	* Returns the result of accumulating the given transformation
4227	>	* of all entries using the given reducer to combine values,
4228	>	* and the given basis as an identity value.
4229	>	*
4230	>	* @param parallelismThreshold the (estimated) number of elements
4231	>	* needed for this operation to be executed in parallel
4232	>	* @param transformer a function returning the transformation
4233	>	* for an element
4234	>	* @param basis the identity (initial default value) for the reduction
4235	>	* @param reducer a commutative associative combining function
4236	>	* @return the result of accumulating the given transformation
4237	>	* of all entries
4238	>	* @since 1.8
4239	>	*/
4240	>	public int reduceEntriesToInt(long parallelismThreshold,
4241	>	ToIntFunction<Map.Entry<K,V>> transformer,
4242	>	int basis,
4243	>	IntBinaryOperator reducer) {
4244	>	if (transformer == null || reducer == null)
4245	>	throw new NullPointerException();
4246	>	return new MapReduceEntriesToIntTask<K,V>
4247	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4248	>	null, transformer, basis, reducer).invoke();
4249	>	}
4250	>
4251	>
4252	>	/* ----------------Views -------------- */
4253	>
4254	>	/**
4255	>	* Base class for views.
4256	>	*/
4257	>	abstract static class CollectionView<K,V,E>
4258	>	implements Collection<E>, java.io.Serializable {
4259	>	private static final long serialVersionUID = 7249069246763182397L;
4260	>	final ConcurrentHashMap<K,V> map;
4261	>	CollectionView(ConcurrentHashMap<K,V> map)  { this.map = map; }
4262	>
4263	>	/**
4264	>	* Returns the map backing this view.
4265	>	*
4266	>	* @return the map backing this view
4267	>	*/
4268	>	public ConcurrentHashMap<K,V> getMap() { return map; }
4269	>
4270	>	/**
4271	>	* Removes all of the elements from this view, by removing all
4272	>	* the mappings from the map backing this view.
4273	>	*/
4274	>	public final void clear()      { map.clear(); }
4275	>	public final int size()        { return map.size(); }
4276	>	public final boolean isEmpty() { return map.isEmpty(); }
4277	>
4278	>	// implementations below rely on concrete classes supplying these
4279	>	// abstract methods
4280	>	/**
4281	>	* Returns an iterator over the elements in this collection.
4282	>	*
4283	>	* <p>The returned iterator is
4284	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
4285	>	*
4286	>	* @return an iterator over the elements in this collection
4287	>	*/
4288	>	public abstract Iterator<E> iterator();
4289	>	public abstract boolean contains(Object o);
4290	>	public abstract boolean remove(Object o);
4291	>
4292	>	private static final String oomeMsg = "Required array size too large";
4293	>
4294	>	public final Object[] toArray() {
4295	>	long sz = map.mappingCount();
4296	>	if (sz > MAX_ARRAY_SIZE)
4297	>	throw new OutOfMemoryError(oomeMsg);
4298	>	int n = (int)sz;
4299	>	Object[] r = new Object[n];
4300	>	int i = 0;
4301	>	for (E e : this) {
4302	>	if (i == n) {
4303	>	if (n >= MAX_ARRAY_SIZE)
4304	>	throw new OutOfMemoryError(oomeMsg);
4305	>	if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4306	>	n = MAX_ARRAY_SIZE;
4307	>	else
4308	>	n += (n >>> 1) + 1;
4309	>	r = Arrays.copyOf(r, n);
4310	>	}
4311	>	r[i++] = e;
4312		}
4313	+	return (i == n) ? r : Arrays.copyOf(r, i);
4314	+	}
4315
4316	<	while (nextSegmentIndex >= 0) {
4317	<	Segment<K,V> seg = (Segment<K,V>)segments[nextSegmentIndex--];
4318	<	if (seg.count != 0) {
4319	<	currentTable = seg.table;
4320	<	for (int j = currentTable.length - 1; j >= 0; --j) {
4321	<	if ( (nextEntry = (HashEntry<K,V>)currentTable[j]) != null) {
4322	<	nextTableIndex = j - 1;
4323	<	return;
4324	<	}
4325	<	}
4316	>	@SuppressWarnings("unchecked")
4317	>	public final <T> T[] toArray(T[] a) {
4318	>	long sz = map.mappingCount();
4319	>	if (sz > MAX_ARRAY_SIZE)
4320	>	throw new OutOfMemoryError(oomeMsg);
4321	>	int m = (int)sz;
4322	>	T[] r = (a.length >= m) ? a :
4323	>	(T[])java.lang.reflect.Array
4324	>	.newInstance(a.getClass().getComponentType(), m);
4325	>	int n = r.length;
4326	>	int i = 0;
4327	>	for (E e : this) {
4328	>	if (i == n) {
4329	>	if (n >= MAX_ARRAY_SIZE)
4330	>	throw new OutOfMemoryError(oomeMsg);
4331	>	if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4332	>	n = MAX_ARRAY_SIZE;
4333	>	else
4334	>	n += (n >>> 1) + 1;
4335	>	r = Arrays.copyOf(r, n);
4336		}
4337	+	r[i++] = (T)e;
4338	+	}
4339	+	if (a == r && i < n) {
4340	+	r[i] = null; // null-terminate
4341	+	return r;
4342		}
4343	+	return (i == n) ? r : Arrays.copyOf(r, i);
4344		}
4345
4346	<	public boolean hasNext() { return nextEntry != null; }
4346	>	/**
4347	>	* Returns a string representation of this collection.
4348	>	* The string representation consists of the string representations
4349	>	* of the collection's elements in the order they are returned by
4350	>	* its iterator, enclosed in square brackets ({@code "[]"}).
4351	>	* Adjacent elements are separated by the characters {@code ", "}
4352	>	* (comma and space).  Elements are converted to strings as by
4353	>	* {@link String#valueOf(Object)}.
4354	>	*
4355	>	* @return a string representation of this collection
4356	>	*/
4357	>	public final String toString() {
4358	>	StringBuilder sb = new StringBuilder();
4359	>	sb.append('[');
4360	>	Iterator<E> it = iterator();
4361	>	if (it.hasNext()) {
4362	>	for (;;) {
4363	>	Object e = it.next();
4364	>	sb.append(e == this ? "(this Collection)" : e);
4365	>	if (!it.hasNext())
4366	>	break;
4367	>	sb.append(',').append(' ');
4368	>	}
4369	>	}
4370	>	return sb.append(']').toString();
4371	>	}
4372
4373	<	HashEntry<K,V> nextEntry() {
4374	<	if (nextEntry == null)
4375	<	throw new NoSuchElementException();
4376	<	lastReturned = nextEntry;
4377	<	advance();
4378	<	return lastReturned;
4373	>	public final boolean containsAll(Collection<?> c) {
4374	>	if (c != this) {
4375	>	for (Object e : c) {
4376	>	if (e == null || !contains(e))
4377	>	return false;
4378	>	}
4379	>	}
4380	>	return true;
4381		}
4382
4383	<	public void remove() {
4384	<	if (lastReturned == null)
4385	<	throw new IllegalStateException();
4386	<	ConcurrentHashMap.this.remove(lastReturned.key);
4387	<	lastReturned = null;
4383	>	public final boolean removeAll(Collection<?> c) {
4384	>	boolean modified = false;
4385	>	for (Iterator<E> it = iterator(); it.hasNext();) {
4386	>	if (c.contains(it.next())) {
4387	>	it.remove();
4388	>	modified = true;
4389	>	}
4390	>	}
4391	>	return modified;
4392		}
1129	–	}
4393
4394	<	final class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> {
4395	<	public K next() { return super.nextEntry().key; }
4396	<	public K nextElement() { return super.nextEntry().key; }
4397	<	}
4394	>	public final boolean retainAll(Collection<?> c) {
4395	>	boolean modified = false;
4396	>	for (Iterator<E> it = iterator(); it.hasNext();) {
4397	>	if (!c.contains(it.next())) {
4398	>	it.remove();
4399	>	modified = true;
4400	>	}
4401	>	}
4402	>	return modified;
4403	>	}
4404
1136	–	final class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> {
1137	–	public V next() { return super.nextEntry().value; }
1138	–	public V nextElement() { return super.nextEntry().value; }
4405		}
4406
1141	–
1142	–
4407		/**
4408	<	* Entry iterator. Exported Entry objects must write-through
4409	<	* changes in setValue, even if the nodes have been cloned. So we
4410	<	* cannot return internal HashEntry objects. Instead, the iterator
4411	<	* itself acts as a forwarding pseudo-entry.
4408	>	* A view of a ConcurrentHashMap as a {@link Set} of keys, in
4409	>	* which additions may optionally be enabled by mapping to a
4410	>	* common value.  This class cannot be directly instantiated.
4411	>	* See {@link #keySet() keySet()},
4412	>	* {@link #keySet(Object) keySet(V)},
4413	>	* {@link #newKeySet() newKeySet()},
4414	>	* {@link #newKeySet(int) newKeySet(int)}.
4415	>	*
4416	>	* @since 1.8
4417		*/
4418	<	final class EntryIterator extends HashIterator implements Map.Entry<K,V>, Iterator<Entry<K,V>> {
4419	<	public Map.Entry<K,V> next() {
4420	<	nextEntry();
4421	<	return this;
4418	>	public static class KeySetView<K,V> extends CollectionView<K,V,K>
4419	>	implements Set<K>, java.io.Serializable {
4420	>	private static final long serialVersionUID = 7249069246763182397L;
4421	>	private final V value;
4422	>	KeySetView(ConcurrentHashMap<K,V> map, V value) {  // non-public
4423	>	super(map);
4424	>	this.value = value;
4425		}
4426
4427	<	public K getKey() {
4428	<	if (lastReturned == null)
4429	<	throw new IllegalStateException("Entry was removed");
4430	<	return lastReturned.key;
4431	<	}
4427	>	/**
4428	>	* Returns the default mapped value for additions,
4429	>	* or {@code null} if additions are not supported.
4430	>	*
4431	>	* @return the default mapped value for additions, or {@code null}
4432	>	* if not supported
4433	>	*/
4434	>	public V getMappedValue() { return value; }
4435
4436	<	public V getValue() {
4437	<	if (lastReturned == null)
4438	<	throw new IllegalStateException("Entry was removed");
4439	<	return ConcurrentHashMap.this.get(lastReturned.key);
4436	>	/**
4437	>	* {@inheritDoc}
4438	>	* @throws NullPointerException if the specified key is null
4439	>	*/
4440	>	public boolean contains(Object o) { return map.containsKey(o); }
4441	>
4442	>	/**
4443	>	* Removes the key from this map view, by removing the key (and its
4444	>	* corresponding value) from the backing map.  This method does
4445	>	* nothing if the key is not in the map.
4446	>	*
4447	>	* @param  o the key to be removed from the backing map
4448	>	* @return {@code true} if the backing map contained the specified key
4449	>	* @throws NullPointerException if the specified key is null
4450	>	*/
4451	>	public boolean remove(Object o) { return map.remove(o) != null; }
4452	>
4453	>	/**
4454	>	* @return an iterator over the keys of the backing map
4455	>	*/
4456	>	public Iterator<K> iterator() {
4457	>	Node<K,V>[] t;
4458	>	ConcurrentHashMap<K,V> m = map;
4459	>	int f = (t = m.table) == null ? 0 : t.length;
4460	>	return new KeyIterator<K,V>(t, f, 0, f, m);
4461		}
4462
4463	<	public V setValue(V value) {
4464	<	if (lastReturned == null)
4465	<	throw new IllegalStateException("Entry was removed");
4466	<	return ConcurrentHashMap.this.put(lastReturned.key, value);
4463	>	/**
4464	>	* Adds the specified key to this set view by mapping the key to
4465	>	* the default mapped value in the backing map, if defined.
4466	>	*
4467	>	* @param e key to be added
4468	>	* @return {@code true} if this set changed as a result of the call
4469	>	* @throws NullPointerException if the specified key is null
4470	>	* @throws UnsupportedOperationException if no default mapped value
4471	>	* for additions was provided
4472	>	*/
4473	>	public boolean add(K e) {
4474	>	V v;
4475	>	if ((v = value) == null)
4476	>	throw new UnsupportedOperationException();
4477	>	return map.putVal(e, v, true) == null;
4478		}
4479
4480	<	public boolean equals(Object o) {
4481	<	// If not acting as entry, just use default.
4482	<	if (lastReturned == null)
4483	<	return super.equals(o);
4484	<	if (!(o instanceof Map.Entry))
4485	<	return false;
4486	<	Map.Entry e = (Map.Entry)o;
4487	<	return eq(getKey(), e.getKey()) && eq(getValue(), e.getValue());
4480	>	/**
4481	>	* Adds all of the elements in the specified collection to this set,
4482	>	* as if by calling {@link #add} on each one.
4483	>	*
4484	>	* @param c the elements to be inserted into this set
4485	>	* @return {@code true} if this set changed as a result of the call
4486	>	* @throws NullPointerException if the collection or any of its
4487	>	* elements are {@code null}
4488	>	* @throws UnsupportedOperationException if no default mapped value
4489	>	* for additions was provided
4490	>	*/
4491	>	public boolean addAll(Collection<? extends K> c) {
4492	>	boolean added = false;
4493	>	V v;
4494	>	if ((v = value) == null)
4495	>	throw new UnsupportedOperationException();
4496	>	for (K e : c) {
4497	>	if (map.putVal(e, v, true) == null)
4498	>	added = true;
4499	>	}
4500	>	return added;
4501		}
4502
4503		public int hashCode() {
4504	<	// If not acting as entry, just use default.
4505	<	if (lastReturned == null)
4506	<	return super.hashCode();
4507	<
1188	<	Object k = getKey();
1189	<	Object v = getValue();
1190	<	return ((k == null) ? 0 : k.hashCode()) ^
1191	<	((v == null) ? 0 : v.hashCode());
4504	>	int h = 0;
4505	>	for (K e : this)
4506	>	h += e.hashCode();
4507	>	return h;
4508		}
4509
4510	<	public String toString() {
4511	<	// If not acting as entry, just use default.
4512	<	if (lastReturned == null)
4513	<	return super.toString();
4514	<	else
4515	<	return getKey() + "=" + getValue();
4510	>	public boolean equals(Object o) {
4511	>	Set<?> c;
4512	>	return ((o instanceof Set) &&
4513	>	((c = (Set<?>)o) == this ||
4514	>	(containsAll(c) && c.containsAll(this))));
4515	>	}
4516	>
4517	>	public Spliterator<K> spliterator() {
4518	>	Node<K,V>[] t;
4519	>	ConcurrentHashMap<K,V> m = map;
4520	>	long n = m.sumCount();
4521	>	int f = (t = m.table) == null ? 0 : t.length;
4522	>	return new KeySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4523	>	}
4524	>
4525	>	public void forEach(Consumer<? super K> action) {
4526	>	if (action == null) throw new NullPointerException();
4527	>	Node<K,V>[] t;
4528	>	if ((t = map.table) != null) {
4529	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4530	>	for (Node<K,V> p; (p = it.advance()) != null; )
4531	>	action.accept(p.key);
4532	>	}
4533		}
4534	+	}
4535
4536	<	boolean eq(Object o1, Object o2) {
4537	<	return (o1 == null ? o2 == null : o1.equals(o2));
4536	>	/**
4537	>	* A view of a ConcurrentHashMap as a {@link Collection} of
4538	>	* values, in which additions are disabled. This class cannot be
4539	>	* directly instantiated. See {@link #values()}.
4540	>	*/
4541	>	static final class ValuesView<K,V> extends CollectionView<K,V,V>
4542	>	implements Collection<V>, java.io.Serializable {
4543	>	private static final long serialVersionUID = 2249069246763182397L;
4544	>	ValuesView(ConcurrentHashMap<K,V> map) { super(map); }
4545	>	public final boolean contains(Object o) {
4546	>	return map.containsValue(o);
4547		}
4548
4549	<	}
4550	<
4551	<	final class KeySet extends AbstractSet<K> {
4552	<	public Iterator<K> iterator() {
4553	<	return new KeyIterator();
4549	>	public final boolean remove(Object o) {
4550	>	if (o != null) {
4551	>	for (Iterator<V> it = iterator(); it.hasNext();) {
4552	>	if (o.equals(it.next())) {
4553	>	it.remove();
4554	>	return true;
4555	>	}
4556	>	}
4557	>	}
4558	>	return false;
4559		}
4560	<	public int size() {
4561	<	return ConcurrentHashMap.this.size();
4560	>
4561	>	public final Iterator<V> iterator() {
4562	>	ConcurrentHashMap<K,V> m = map;
4563	>	Node<K,V>[] t;
4564	>	int f = (t = m.table) == null ? 0 : t.length;
4565	>	return new ValueIterator<K,V>(t, f, 0, f, m);
4566	>	}
4567	>
4568	>	public final boolean add(V e) {
4569	>	throw new UnsupportedOperationException();
4570	>	}
4571	>	public final boolean addAll(Collection<? extends V> c) {
4572	>	throw new UnsupportedOperationException();
4573	>	}
4574	>
4575	>	public Spliterator<V> spliterator() {
4576	>	Node<K,V>[] t;
4577	>	ConcurrentHashMap<K,V> m = map;
4578	>	long n = m.sumCount();
4579	>	int f = (t = m.table) == null ? 0 : t.length;
4580	>	return new ValueSpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4581	>	}
4582	>
4583	>	public void forEach(Consumer<? super V> action) {
4584	>	if (action == null) throw new NullPointerException();
4585	>	Node<K,V>[] t;
4586	>	if ((t = map.table) != null) {
4587	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4588	>	for (Node<K,V> p; (p = it.advance()) != null; )
4589	>	action.accept(p.val);
4590	>	}
4591		}
4592	+	}
4593	+
4594	+	/**
4595	+	* A view of a ConcurrentHashMap as a {@link Set} of (key, value)
4596	+	* entries.  This class cannot be directly instantiated. See
4597	+	* {@link #entrySet()}.
4598	+	*/
4599	+	static final class EntrySetView<K,V> extends CollectionView<K,V,Map.Entry<K,V>>
4600	+	implements Set<Map.Entry<K,V>>, java.io.Serializable {
4601	+	private static final long serialVersionUID = 2249069246763182397L;
4602	+	EntrySetView(ConcurrentHashMap<K,V> map) { super(map); }
4603	+
4604		public boolean contains(Object o) {
4605	<	return ConcurrentHashMap.this.containsKey(o);
4605	>	Object k, v, r; Map.Entry<?,?> e;
4606	>	return ((o instanceof Map.Entry) &&
4607	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4608	>	(r = map.get(k)) != null &&
4609	>	(v = e.getValue()) != null &&
4610	>	(v == r || v.equals(r)));
4611		}
4612	+
4613		public boolean remove(Object o) {
4614	<	return ConcurrentHashMap.this.remove(o) != null;
4614	>	Object k, v; Map.Entry<?,?> e;
4615	>	return ((o instanceof Map.Entry) &&
4616	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4617	>	(v = e.getValue()) != null &&
4618	>	map.remove(k, v));
4619		}
4620	<	public void clear() {
4621	<	ConcurrentHashMap.this.clear();
4620	>
4621	>	/**
4622	>	* @return an iterator over the entries of the backing map
4623	>	*/
4624	>	public Iterator<Map.Entry<K,V>> iterator() {
4625	>	ConcurrentHashMap<K,V> m = map;
4626	>	Node<K,V>[] t;
4627	>	int f = (t = m.table) == null ? 0 : t.length;
4628	>	return new EntryIterator<K,V>(t, f, 0, f, m);
4629	>	}
4630	>
4631	>	public boolean add(Entry<K,V> e) {
4632	>	return map.putVal(e.getKey(), e.getValue(), false) == null;
4633		}
4634	<	public Object[] toArray() {
4635	<	Collection<K> c = new ArrayList<K>();
4636	<	for (Iterator<K> i = iterator(); i.hasNext(); )
4637	<	c.add(i.next());
4638	<	return c.toArray();
4634	>
4635	>	public boolean addAll(Collection<? extends Entry<K,V>> c) {
4636	>	boolean added = false;
4637	>	for (Entry<K,V> e : c) {
4638	>	if (add(e))
4639	>	added = true;
4640	>	}
4641	>	return added;
4642	>	}
4643	>
4644	>	public final int hashCode() {
4645	>	int h = 0;
4646	>	Node<K,V>[] t;
4647	>	if ((t = map.table) != null) {
4648	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4649	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
4650	>	h += p.hashCode();
4651	>	}
4652	>	}
4653	>	return h;
4654		}
4655	<	public <T> T[] toArray(T[] a) {
4656	<	Collection<K> c = new ArrayList<K>();
4657	<	for (Iterator<K> i = iterator(); i.hasNext(); )
4658	<	c.add(i.next());
4659	<	return c.toArray(a);
4655	>
4656	>	public final boolean equals(Object o) {
4657	>	Set<?> c;
4658	>	return ((o instanceof Set) &&
4659	>	((c = (Set<?>)o) == this ||
4660	>	(containsAll(c) && c.containsAll(this))));
4661	>	}
4662	>
4663	>	public Spliterator<Map.Entry<K,V>> spliterator() {
4664	>	Node<K,V>[] t;
4665	>	ConcurrentHashMap<K,V> m = map;
4666	>	long n = m.sumCount();
4667	>	int f = (t = m.table) == null ? 0 : t.length;
4668	>	return new EntrySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n, m);
4669	>	}
4670	>
4671	>	public void forEach(Consumer<? super Map.Entry<K,V>> action) {
4672	>	if (action == null) throw new NullPointerException();
4673	>	Node<K,V>[] t;
4674	>	if ((t = map.table) != null) {
4675	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4676	>	for (Node<K,V> p; (p = it.advance()) != null; )
4677	>	action.accept(new MapEntry<K,V>(p.key, p.val, map));
4678	>	}
4679		}
4680	+
4681		}
4682
4683	<	final class Values extends AbstractCollection<V> {
4684	<	public Iterator<V> iterator() {
4685	<	return new ValueIterator();
4683	>	// -------------------------------------------------------
4684	>
4685	>	/**
4686	>	* Base class for bulk tasks. Repeats some fields and code from
4687	>	* class Traverser, because we need to subclass CountedCompleter.
4688	>	*/
4689	>	abstract static class BulkTask<K,V,R> extends CountedCompleter<R> {
4690	>	Node<K,V>[] tab;        // same as Traverser
4691	>	Node<K,V> next;
4692	>	int index;
4693	>	int baseIndex;
4694	>	int baseLimit;
4695	>	final int baseSize;
4696	>	int batch;              // split control
4697	>
4698	>	BulkTask(BulkTask<K,V,?> par, int b, int i, int f, Node<K,V>[] t) {
4699	>	super(par);
4700	>	this.batch = b;
4701	>	this.index = this.baseIndex = i;
4702	>	if ((this.tab = t) == null)
4703	>	this.baseSize = this.baseLimit = 0;
4704	>	else if (par == null)
4705	>	this.baseSize = this.baseLimit = t.length;
4706	>	else {
4707	>	this.baseLimit = f;
4708	>	this.baseSize = par.baseSize;
4709	>	}
4710		}
4711	<	public int size() {
4712	<	return ConcurrentHashMap.this.size();
4711	>
4712	>	/**
4713	>	* Same as Traverser version
4714	>	*/
4715	>	final Node<K,V> advance() {
4716	>	Node<K,V> e;
4717	>	if ((e = next) != null)
4718	>	e = e.next;
4719	>	for (;;) {
4720	>	Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
4721	>	if (e != null)
4722	>	return next = e;
4723	>	if (baseIndex >= baseLimit || (t = tab) == null ||
4724	>	(n = t.length) <= (i = index) || i < 0)
4725	>	return next = null;
4726	>	if ((e = tabAt(t, index)) != null && e.hash < 0) {
4727	>	if (e instanceof ForwardingNode) {
4728	>	tab = ((ForwardingNode<K,V>)e).nextTable;
4729	>	e = null;
4730	>	continue;
4731	>	}
4732	>	else if (e instanceof TreeBin)
4733	>	e = ((TreeBin<K,V>)e).first;
4734	>	else
4735	>	e = null;
4736	>	}
4737	>	if ((index += baseSize) >= n)
4738	>	index = ++baseIndex;    // visit upper slots if present
4739	>	}
4740		}
4741	<	public boolean contains(Object o) {
4742	<	return ConcurrentHashMap.this.containsValue(o);
4741	>	}
4742	>
4743	>	/*
4744	>	* Task classes. Coded in a regular but ugly format/style to
4745	>	* simplify checks that each variant differs in the right way from
4746	>	* others. The null screenings exist because compilers cannot tell
4747	>	* that we've already null-checked task arguments, so we force
4748	>	* simplest hoisted bypass to help avoid convoluted traps.
4749	>	*/
4750	>	@SuppressWarnings("serial")
4751	>	static final class ForEachKeyTask<K,V>
4752	>	extends BulkTask<K,V,Void> {
4753	>	final Consumer<? super K> action;
4754	>	ForEachKeyTask
4755	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4756	>	Consumer<? super K> action) {
4757	>	super(p, b, i, f, t);
4758	>	this.action = action;
4759	>	}
4760	>	public final void compute() {
4761	>	final Consumer<? super K> action;
4762	>	if ((action = this.action) != null) {
4763	>	for (int i = baseIndex, f, h; batch > 0 &&
4764	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4765	>	addToPendingCount(1);
4766	>	new ForEachKeyTask<K,V>
4767	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4768	>	action).fork();
4769	>	}
4770	>	for (Node<K,V> p; (p = advance()) != null;)
4771	>	action.accept(p.key);
4772	>	propagateCompletion();
4773	>	}
4774		}
4775	<	public void clear() {
4776	<	ConcurrentHashMap.this.clear();
4775	>	}
4776	>
4777	>	@SuppressWarnings("serial")
4778	>	static final class ForEachValueTask<K,V>
4779	>	extends BulkTask<K,V,Void> {
4780	>	final Consumer<? super V> action;
4781	>	ForEachValueTask
4782	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4783	>	Consumer<? super V> action) {
4784	>	super(p, b, i, f, t);
4785	>	this.action = action;
4786	>	}
4787	>	public final void compute() {
4788	>	final Consumer<? super V> action;
4789	>	if ((action = this.action) != null) {
4790	>	for (int i = baseIndex, f, h; batch > 0 &&
4791	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4792	>	addToPendingCount(1);
4793	>	new ForEachValueTask<K,V>
4794	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4795	>	action).fork();
4796	>	}
4797	>	for (Node<K,V> p; (p = advance()) != null;)
4798	>	action.accept(p.val);
4799	>	propagateCompletion();
4800	>	}
4801		}
4802	<	public Object[] toArray() {
4803	<	Collection<V> c = new ArrayList<V>();
4804	<	for (Iterator<V> i = iterator(); i.hasNext(); )
4805	<	c.add(i.next());
4806	<	return c.toArray();
4802	>	}
4803	>
4804	>	@SuppressWarnings("serial")
4805	>	static final class ForEachEntryTask<K,V>
4806	>	extends BulkTask<K,V,Void> {
4807	>	final Consumer<? super Entry<K,V>> action;
4808	>	ForEachEntryTask
4809	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4810	>	Consumer<? super Entry<K,V>> action) {
4811	>	super(p, b, i, f, t);
4812	>	this.action = action;
4813	>	}
4814	>	public final void compute() {
4815	>	final Consumer<? super Entry<K,V>> action;
4816	>	if ((action = this.action) != null) {
4817	>	for (int i = baseIndex, f, h; batch > 0 &&
4818	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4819	>	addToPendingCount(1);
4820	>	new ForEachEntryTask<K,V>
4821	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4822	>	action).fork();
4823	>	}
4824	>	for (Node<K,V> p; (p = advance()) != null; )
4825	>	action.accept(p);
4826	>	propagateCompletion();
4827	>	}
4828		}
4829	<	public <T> T[] toArray(T[] a) {
4830	<	Collection<V> c = new ArrayList<V>();
4831	<	for (Iterator<V> i = iterator(); i.hasNext(); )
4832	<	c.add(i.next());
4833	<	return c.toArray(a);
4829	>	}
4830	>
4831	>	@SuppressWarnings("serial")
4832	>	static final class ForEachMappingTask<K,V>
4833	>	extends BulkTask<K,V,Void> {
4834	>	final BiConsumer<? super K, ? super V> action;
4835	>	ForEachMappingTask
4836	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4837	>	BiConsumer<? super K,? super V> action) {
4838	>	super(p, b, i, f, t);
4839	>	this.action = action;
4840	>	}
4841	>	public final void compute() {
4842	>	final BiConsumer<? super K, ? super V> action;
4843	>	if ((action = this.action) != null) {
4844	>	for (int i = baseIndex, f, h; batch > 0 &&
4845	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4846	>	addToPendingCount(1);
4847	>	new ForEachMappingTask<K,V>
4848	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4849	>	action).fork();
4850	>	}
4851	>	for (Node<K,V> p; (p = advance()) != null; )
4852	>	action.accept(p.key, p.val);
4853	>	propagateCompletion();
4854	>	}
4855		}
4856		}
4857
4858	<	final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
4859	<	public Iterator<Map.Entry<K,V>> iterator() {
4860	<	return new EntryIterator();
4858	>	@SuppressWarnings("serial")
4859	>	static final class ForEachTransformedKeyTask<K,V,U>
4860	>	extends BulkTask<K,V,Void> {
4861	>	final Function<? super K, ? extends U> transformer;
4862	>	final Consumer<? super U> action;
4863	>	ForEachTransformedKeyTask
4864	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4865	>	Function<? super K, ? extends U> transformer, Consumer<? super U> action) {
4866	>	super(p, b, i, f, t);
4867	>	this.transformer = transformer; this.action = action;
4868	>	}
4869	>	public final void compute() {
4870	>	final Function<? super K, ? extends U> transformer;
4871	>	final Consumer<? super U> action;
4872	>	if ((transformer = this.transformer) != null &&
4873	>	(action = this.action) != null) {
4874	>	for (int i = baseIndex, f, h; batch > 0 &&
4875	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4876	>	addToPendingCount(1);
4877	>	new ForEachTransformedKeyTask<K,V,U>
4878	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4879	>	transformer, action).fork();
4880	>	}
4881	>	for (Node<K,V> p; (p = advance()) != null; ) {
4882	>	U u;
4883	>	if ((u = transformer.apply(p.key)) != null)
4884	>	action.accept(u);
4885	>	}
4886	>	propagateCompletion();
4887	>	}
4888		}
4889	<	public boolean contains(Object o) {
4890	<	if (!(o instanceof Map.Entry))
4891	<	return false;
4892	<	Map.Entry<K,V> e = (Map.Entry<K,V>)o;
4893	<	V v = ConcurrentHashMap.this.get(e.getKey());
4894	<	return v != null && v.equals(e.getValue());
4889	>	}
4890	>
4891	>	@SuppressWarnings("serial")
4892	>	static final class ForEachTransformedValueTask<K,V,U>
4893	>	extends BulkTask<K,V,Void> {
4894	>	final Function<? super V, ? extends U> transformer;
4895	>	final Consumer<? super U> action;
4896	>	ForEachTransformedValueTask
4897	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4898	>	Function<? super V, ? extends U> transformer, Consumer<? super U> action) {
4899	>	super(p, b, i, f, t);
4900	>	this.transformer = transformer; this.action = action;
4901	>	}
4902	>	public final void compute() {
4903	>	final Function<? super V, ? extends U> transformer;
4904	>	final Consumer<? super U> action;
4905	>	if ((transformer = this.transformer) != null &&
4906	>	(action = this.action) != null) {
4907	>	for (int i = baseIndex, f, h; batch > 0 &&
4908	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4909	>	addToPendingCount(1);
4910	>	new ForEachTransformedValueTask<K,V,U>
4911	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4912	>	transformer, action).fork();
4913	>	}
4914	>	for (Node<K,V> p; (p = advance()) != null; ) {
4915	>	U u;
4916	>	if ((u = transformer.apply(p.val)) != null)
4917	>	action.accept(u);
4918	>	}
4919	>	propagateCompletion();
4920	>	}
4921		}
4922	<	public boolean remove(Object o) {
4923	<	if (!(o instanceof Map.Entry))
4924	<	return false;
4925	<	Map.Entry<K,V> e = (Map.Entry<K,V>)o;
4926	<	return ConcurrentHashMap.this.remove(e.getKey(), e.getValue());
4922	>	}
4923	>
4924	>	@SuppressWarnings("serial")
4925	>	static final class ForEachTransformedEntryTask<K,V,U>
4926	>	extends BulkTask<K,V,Void> {
4927	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
4928	>	final Consumer<? super U> action;
4929	>	ForEachTransformedEntryTask
4930	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4931	>	Function<Map.Entry<K,V>, ? extends U> transformer, Consumer<? super U> action) {
4932	>	super(p, b, i, f, t);
4933	>	this.transformer = transformer; this.action = action;
4934	>	}
4935	>	public final void compute() {
4936	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
4937	>	final Consumer<? super U> action;
4938	>	if ((transformer = this.transformer) != null &&
4939	>	(action = this.action) != null) {
4940	>	for (int i = baseIndex, f, h; batch > 0 &&
4941	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4942	>	addToPendingCount(1);
4943	>	new ForEachTransformedEntryTask<K,V,U>
4944	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4945	>	transformer, action).fork();
4946	>	}
4947	>	for (Node<K,V> p; (p = advance()) != null; ) {
4948	>	U u;
4949	>	if ((u = transformer.apply(p)) != null)
4950	>	action.accept(u);
4951	>	}
4952	>	propagateCompletion();
4953	>	}
4954	>	}
4955	>	}
4956	>
4957	>	@SuppressWarnings("serial")
4958	>	static final class ForEachTransformedMappingTask<K,V,U>
4959	>	extends BulkTask<K,V,Void> {
4960	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
4961	>	final Consumer<? super U> action;
4962	>	ForEachTransformedMappingTask
4963	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4964	>	BiFunction<? super K, ? super V, ? extends U> transformer,
4965	>	Consumer<? super U> action) {
4966	>	super(p, b, i, f, t);
4967	>	this.transformer = transformer; this.action = action;
4968	>	}
4969	>	public final void compute() {
4970	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
4971	>	final Consumer<? super U> action;
4972	>	if ((transformer = this.transformer) != null &&
4973	>	(action = this.action) != null) {
4974	>	for (int i = baseIndex, f, h; batch > 0 &&
4975	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4976	>	addToPendingCount(1);
4977	>	new ForEachTransformedMappingTask<K,V,U>
4978	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4979	>	transformer, action).fork();
4980	>	}
4981	>	for (Node<K,V> p; (p = advance()) != null; ) {
4982	>	U u;
4983	>	if ((u = transformer.apply(p.key, p.val)) != null)
4984	>	action.accept(u);
4985	>	}
4986	>	propagateCompletion();
4987	>	}
4988	>	}
4989	>	}
4990	>
4991	>	@SuppressWarnings("serial")
4992	>	static final class SearchKeysTask<K,V,U>
4993	>	extends BulkTask<K,V,U> {
4994	>	final Function<? super K, ? extends U> searchFunction;
4995	>	final AtomicReference<U> result;
4996	>	SearchKeysTask
4997	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4998	>	Function<? super K, ? extends U> searchFunction,
4999	>	AtomicReference<U> result) {
5000	>	super(p, b, i, f, t);
5001	>	this.searchFunction = searchFunction; this.result = result;
5002	>	}
5003	>	public final U getRawResult() { return result.get(); }
5004	>	public final void compute() {
5005	>	final Function<? super K, ? extends U> searchFunction;
5006	>	final AtomicReference<U> result;
5007	>	if ((searchFunction = this.searchFunction) != null &&
5008	>	(result = this.result) != null) {
5009	>	for (int i = baseIndex, f, h; batch > 0 &&
5010	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5011	>	if (result.get() != null)
5012	>	return;
5013	>	addToPendingCount(1);
5014	>	new SearchKeysTask<K,V,U>
5015	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5016	>	searchFunction, result).fork();
5017	>	}
5018	>	while (result.get() == null) {
5019	>	U u;
5020	>	Node<K,V> p;
5021	>	if ((p = advance()) == null) {
5022	>	propagateCompletion();
5023	>	break;
5024	>	}
5025	>	if ((u = searchFunction.apply(p.key)) != null) {
5026	>	if (result.compareAndSet(null, u))
5027	>	quietlyCompleteRoot();
5028	>	break;
5029	>	}
5030	>	}
5031	>	}
5032		}
5033	<	public int size() {
5034	<	return ConcurrentHashMap.this.size();
5033	>	}
5034	>
5035	>	@SuppressWarnings("serial")
5036	>	static final class SearchValuesTask<K,V,U>
5037	>	extends BulkTask<K,V,U> {
5038	>	final Function<? super V, ? extends U> searchFunction;
5039	>	final AtomicReference<U> result;
5040	>	SearchValuesTask
5041	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5042	>	Function<? super V, ? extends U> searchFunction,
5043	>	AtomicReference<U> result) {
5044	>	super(p, b, i, f, t);
5045	>	this.searchFunction = searchFunction; this.result = result;
5046	>	}
5047	>	public final U getRawResult() { return result.get(); }
5048	>	public final void compute() {
5049	>	final Function<? super V, ? extends U> searchFunction;
5050	>	final AtomicReference<U> result;
5051	>	if ((searchFunction = this.searchFunction) != null &&
5052	>	(result = this.result) != null) {
5053	>	for (int i = baseIndex, f, h; batch > 0 &&
5054	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5055	>	if (result.get() != null)
5056	>	return;
5057	>	addToPendingCount(1);
5058	>	new SearchValuesTask<K,V,U>
5059	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5060	>	searchFunction, result).fork();
5061	>	}
5062	>	while (result.get() == null) {
5063	>	U u;
5064	>	Node<K,V> p;
5065	>	if ((p = advance()) == null) {
5066	>	propagateCompletion();
5067	>	break;
5068	>	}
5069	>	if ((u = searchFunction.apply(p.val)) != null) {
5070	>	if (result.compareAndSet(null, u))
5071	>	quietlyCompleteRoot();
5072	>	break;
5073	>	}
5074	>	}
5075	>	}
5076		}
5077	<	public void clear() {
5078	<	ConcurrentHashMap.this.clear();
5077	>	}
5078	>
5079	>	@SuppressWarnings("serial")
5080	>	static final class SearchEntriesTask<K,V,U>
5081	>	extends BulkTask<K,V,U> {
5082	>	final Function<Entry<K,V>, ? extends U> searchFunction;
5083	>	final AtomicReference<U> result;
5084	>	SearchEntriesTask
5085	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5086	>	Function<Entry<K,V>, ? extends U> searchFunction,
5087	>	AtomicReference<U> result) {
5088	>	super(p, b, i, f, t);
5089	>	this.searchFunction = searchFunction; this.result = result;
5090	>	}
5091	>	public final U getRawResult() { return result.get(); }
5092	>	public final void compute() {
5093	>	final Function<Entry<K,V>, ? extends U> searchFunction;
5094	>	final AtomicReference<U> result;
5095	>	if ((searchFunction = this.searchFunction) != null &&
5096	>	(result = this.result) != null) {
5097	>	for (int i = baseIndex, f, h; batch > 0 &&
5098	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5099	>	if (result.get() != null)
5100	>	return;
5101	>	addToPendingCount(1);
5102	>	new SearchEntriesTask<K,V,U>
5103	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5104	>	searchFunction, result).fork();
5105	>	}
5106	>	while (result.get() == null) {
5107	>	U u;
5108	>	Node<K,V> p;
5109	>	if ((p = advance()) == null) {
5110	>	propagateCompletion();
5111	>	break;
5112	>	}
5113	>	if ((u = searchFunction.apply(p)) != null) {
5114	>	if (result.compareAndSet(null, u))
5115	>	quietlyCompleteRoot();
5116	>	return;
5117	>	}
5118	>	}
5119	>	}
5120		}
5121	<	public Object[] toArray() {
5122	<	// Since we don't ordinarily have distinct Entry objects, we
5123	<	// must pack elements using exportable SimpleEntry
5124	<	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
5125	<	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
5126	<	c.add(new SimpleEntry<K,V>(i.next()));
5127	<	return c.toArray();
5121	>	}
5122	>
5123	>	@SuppressWarnings("serial")
5124	>	static final class SearchMappingsTask<K,V,U>
5125	>	extends BulkTask<K,V,U> {
5126	>	final BiFunction<? super K, ? super V, ? extends U> searchFunction;
5127	>	final AtomicReference<U> result;
5128	>	SearchMappingsTask
5129	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5130	>	BiFunction<? super K, ? super V, ? extends U> searchFunction,
5131	>	AtomicReference<U> result) {
5132	>	super(p, b, i, f, t);
5133	>	this.searchFunction = searchFunction; this.result = result;
5134	>	}
5135	>	public final U getRawResult() { return result.get(); }
5136	>	public final void compute() {
5137	>	final BiFunction<? super K, ? super V, ? extends U> searchFunction;
5138	>	final AtomicReference<U> result;
5139	>	if ((searchFunction = this.searchFunction) != null &&
5140	>	(result = this.result) != null) {
5141	>	for (int i = baseIndex, f, h; batch > 0 &&
5142	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5143	>	if (result.get() != null)
5144	>	return;
5145	>	addToPendingCount(1);
5146	>	new SearchMappingsTask<K,V,U>
5147	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5148	>	searchFunction, result).fork();
5149	>	}
5150	>	while (result.get() == null) {
5151	>	U u;
5152	>	Node<K,V> p;
5153	>	if ((p = advance()) == null) {
5154	>	propagateCompletion();
5155	>	break;
5156	>	}
5157	>	if ((u = searchFunction.apply(p.key, p.val)) != null) {
5158	>	if (result.compareAndSet(null, u))
5159	>	quietlyCompleteRoot();
5160	>	break;
5161	>	}
5162	>	}
5163	>	}
5164		}
5165	<	public <T> T[] toArray(T[] a) {
5166	<	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
5167	<	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
5168	<	c.add(new SimpleEntry<K,V>(i.next()));
5169	<	return c.toArray(a);
5165	>	}
5166	>
5167	>	@SuppressWarnings("serial")
5168	>	static final class ReduceKeysTask<K,V>
5169	>	extends BulkTask<K,V,K> {
5170	>	final BiFunction<? super K, ? super K, ? extends K> reducer;
5171	>	K result;
5172	>	ReduceKeysTask<K,V> rights, nextRight;
5173	>	ReduceKeysTask
5174	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5175	>	ReduceKeysTask<K,V> nextRight,
5176	>	BiFunction<? super K, ? super K, ? extends K> reducer) {
5177	>	super(p, b, i, f, t); this.nextRight = nextRight;
5178	>	this.reducer = reducer;
5179	>	}
5180	>	public final K getRawResult() { return result; }
5181	>	public final void compute() {
5182	>	final BiFunction<? super K, ? super K, ? extends K> reducer;
5183	>	if ((reducer = this.reducer) != null) {
5184	>	for (int i = baseIndex, f, h; batch > 0 &&
5185	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5186	>	addToPendingCount(1);
5187	>	(rights = new ReduceKeysTask<K,V>
5188	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5189	>	rights, reducer)).fork();
5190	>	}
5191	>	K r = null;
5192	>	for (Node<K,V> p; (p = advance()) != null; ) {
5193	>	K u = p.key;
5194	>	r = (r == null) ? u : u == null ? r : reducer.apply(r, u);
5195	>	}
5196	>	result = r;
5197	>	CountedCompleter<?> c;
5198	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5199	>	@SuppressWarnings("unchecked") ReduceKeysTask<K,V>
5200	>	t = (ReduceKeysTask<K,V>)c,
5201	>	s = t.rights;
5202	>	while (s != null) {
5203	>	K tr, sr;
5204	>	if ((sr = s.result) != null)
5205	>	t.result = (((tr = t.result) == null) ? sr :
5206	>	reducer.apply(tr, sr));
5207	>	s = t.rights = s.nextRight;
5208	>	}
5209	>	}
5210	>	}
5211		}
5212	+	}
5213
5214	+	@SuppressWarnings("serial")
5215	+	static final class ReduceValuesTask<K,V>
5216	+	extends BulkTask<K,V,V> {
5217	+	final BiFunction<? super V, ? super V, ? extends V> reducer;
5218	+	V result;
5219	+	ReduceValuesTask<K,V> rights, nextRight;
5220	+	ReduceValuesTask
5221	+	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5222	+	ReduceValuesTask<K,V> nextRight,
5223	+	BiFunction<? super V, ? super V, ? extends V> reducer) {
5224	+	super(p, b, i, f, t); this.nextRight = nextRight;
5225	+	this.reducer = reducer;
5226	+	}
5227	+	public final V getRawResult() { return result; }
5228	+	public final void compute() {
5229	+	final BiFunction<? super V, ? super V, ? extends V> reducer;
5230	+	if ((reducer = this.reducer) != null) {
5231	+	for (int i = baseIndex, f, h; batch > 0 &&
5232	+	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5233	+	addToPendingCount(1);
5234	+	(rights = new ReduceValuesTask<K,V>
5235	+	(this, batch >>>= 1, baseLimit = h, f, tab,
5236	+	rights, reducer)).fork();
5237	+	}
5238	+	V r = null;
5239	+	for (Node<K,V> p; (p = advance()) != null; ) {
5240	+	V v = p.val;
5241	+	r = (r == null) ? v : reducer.apply(r, v);
5242	+	}
5243	+	result = r;
5244	+	CountedCompleter<?> c;
5245	+	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5246	+	@SuppressWarnings("unchecked") ReduceValuesTask<K,V>
5247	+	t = (ReduceValuesTask<K,V>)c,
5248	+	s = t.rights;
5249	+	while (s != null) {
5250	+	V tr, sr;
5251	+	if ((sr = s.result) != null)
5252	+	t.result = (((tr = t.result) == null) ? sr :
5253	+	reducer.apply(tr, sr));
5254	+	s = t.rights = s.nextRight;
5255	+	}
5256	+	}
5257	+	}
5258	+	}
5259		}
5260
5261	<	/**
5262	<	* This duplicates java.util.AbstractMap.SimpleEntry until this class
5263	<	* is made accessible.
5264	<	*/
5265	<	static final class SimpleEntry<K,V> implements Entry<K,V> {
5266	<	K key;
5267	<	V value;
5261	>	@SuppressWarnings("serial")
5262	>	static final class ReduceEntriesTask<K,V>
5263	>	extends BulkTask<K,V,Map.Entry<K,V>> {
5264	>	final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5265	>	Map.Entry<K,V> result;
5266	>	ReduceEntriesTask<K,V> rights, nextRight;
5267	>	ReduceEntriesTask
5268	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5269	>	ReduceEntriesTask<K,V> nextRight,
5270	>	BiFunction<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5271	>	super(p, b, i, f, t); this.nextRight = nextRight;
5272	>	this.reducer = reducer;
5273	>	}
5274	>	public final Map.Entry<K,V> getRawResult() { return result; }
5275	>	public final void compute() {
5276	>	final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5277	>	if ((reducer = this.reducer) != null) {
5278	>	for (int i = baseIndex, f, h; batch > 0 &&
5279	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5280	>	addToPendingCount(1);
5281	>	(rights = new ReduceEntriesTask<K,V>
5282	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5283	>	rights, reducer)).fork();
5284	>	}
5285	>	Map.Entry<K,V> r = null;
5286	>	for (Node<K,V> p; (p = advance()) != null; )
5287	>	r = (r == null) ? p : reducer.apply(r, p);
5288	>	result = r;
5289	>	CountedCompleter<?> c;
5290	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5291	>	@SuppressWarnings("unchecked") ReduceEntriesTask<K,V>
5292	>	t = (ReduceEntriesTask<K,V>)c,
5293	>	s = t.rights;
5294	>	while (s != null) {
5295	>	Map.Entry<K,V> tr, sr;
5296	>	if ((sr = s.result) != null)
5297	>	t.result = (((tr = t.result) == null) ? sr :
5298	>	reducer.apply(tr, sr));
5299	>	s = t.rights = s.nextRight;
5300	>	}
5301	>	}
5302	>	}
5303	>	}
5304	>	}
5305
5306	<	public SimpleEntry(K key, V value) {
5307	<	this.key   = key;
5308	<	this.value = value;
5306	>	@SuppressWarnings("serial")
5307	>	static final class MapReduceKeysTask<K,V,U>
5308	>	extends BulkTask<K,V,U> {
5309	>	final Function<? super K, ? extends U> transformer;
5310	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5311	>	U result;
5312	>	MapReduceKeysTask<K,V,U> rights, nextRight;
5313	>	MapReduceKeysTask
5314	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5315	>	MapReduceKeysTask<K,V,U> nextRight,
5316	>	Function<? super K, ? extends U> transformer,
5317	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5318	>	super(p, b, i, f, t); this.nextRight = nextRight;
5319	>	this.transformer = transformer;
5320	>	this.reducer = reducer;
5321	>	}
5322	>	public final U getRawResult() { return result; }
5323	>	public final void compute() {
5324	>	final Function<? super K, ? extends U> transformer;
5325	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5326	>	if ((transformer = this.transformer) != null &&
5327	>	(reducer = this.reducer) != null) {
5328	>	for (int i = baseIndex, f, h; batch > 0 &&
5329	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5330	>	addToPendingCount(1);
5331	>	(rights = new MapReduceKeysTask<K,V,U>
5332	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5333	>	rights, transformer, reducer)).fork();
5334	>	}
5335	>	U r = null;
5336	>	for (Node<K,V> p; (p = advance()) != null; ) {
5337	>	U u;
5338	>	if ((u = transformer.apply(p.key)) != null)
5339	>	r = (r == null) ? u : reducer.apply(r, u);
5340	>	}
5341	>	result = r;
5342	>	CountedCompleter<?> c;
5343	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5344	>	@SuppressWarnings("unchecked") MapReduceKeysTask<K,V,U>
5345	>	t = (MapReduceKeysTask<K,V,U>)c,
5346	>	s = t.rights;
5347	>	while (s != null) {
5348	>	U tr, sr;
5349	>	if ((sr = s.result) != null)
5350	>	t.result = (((tr = t.result) == null) ? sr :
5351	>	reducer.apply(tr, sr));
5352	>	s = t.rights = s.nextRight;
5353	>	}
5354	>	}
5355	>	}
5356		}
5357	+	}
5358
5359	<	public SimpleEntry(Entry<K,V> e) {
5360	<	this.key   = e.getKey();
5361	<	this.value = e.getValue();
5359	>	@SuppressWarnings("serial")
5360	>	static final class MapReduceValuesTask<K,V,U>
5361	>	extends BulkTask<K,V,U> {
5362	>	final Function<? super V, ? extends U> transformer;
5363	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5364	>	U result;
5365	>	MapReduceValuesTask<K,V,U> rights, nextRight;
5366	>	MapReduceValuesTask
5367	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5368	>	MapReduceValuesTask<K,V,U> nextRight,
5369	>	Function<? super V, ? extends U> transformer,
5370	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5371	>	super(p, b, i, f, t); this.nextRight = nextRight;
5372	>	this.transformer = transformer;
5373	>	this.reducer = reducer;
5374	>	}
5375	>	public final U getRawResult() { return result; }
5376	>	public final void compute() {
5377	>	final Function<? super V, ? extends U> transformer;
5378	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5379	>	if ((transformer = this.transformer) != null &&
5380	>	(reducer = this.reducer) != null) {
5381	>	for (int i = baseIndex, f, h; batch > 0 &&
5382	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5383	>	addToPendingCount(1);
5384	>	(rights = new MapReduceValuesTask<K,V,U>
5385	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5386	>	rights, transformer, reducer)).fork();
5387	>	}
5388	>	U r = null;
5389	>	for (Node<K,V> p; (p = advance()) != null; ) {
5390	>	U u;
5391	>	if ((u = transformer.apply(p.val)) != null)
5392	>	r = (r == null) ? u : reducer.apply(r, u);
5393	>	}
5394	>	result = r;
5395	>	CountedCompleter<?> c;
5396	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5397	>	@SuppressWarnings("unchecked") MapReduceValuesTask<K,V,U>
5398	>	t = (MapReduceValuesTask<K,V,U>)c,
5399	>	s = t.rights;
5400	>	while (s != null) {
5401	>	U tr, sr;
5402	>	if ((sr = s.result) != null)
5403	>	t.result = (((tr = t.result) == null) ? sr :
5404	>	reducer.apply(tr, sr));
5405	>	s = t.rights = s.nextRight;
5406	>	}
5407	>	}
5408	>	}
5409		}
5410	+	}
5411
5412	<	public K getKey() {
5413	<	return key;
5412	>	@SuppressWarnings("serial")
5413	>	static final class MapReduceEntriesTask<K,V,U>
5414	>	extends BulkTask<K,V,U> {
5415	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5416	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5417	>	U result;
5418	>	MapReduceEntriesTask<K,V,U> rights, nextRight;
5419	>	MapReduceEntriesTask
5420	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5421	>	MapReduceEntriesTask<K,V,U> nextRight,
5422	>	Function<Map.Entry<K,V>, ? extends U> transformer,
5423	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5424	>	super(p, b, i, f, t); this.nextRight = nextRight;
5425	>	this.transformer = transformer;
5426	>	this.reducer = reducer;
5427	>	}
5428	>	public final U getRawResult() { return result; }
5429	>	public final void compute() {
5430	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5431	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5432	>	if ((transformer = this.transformer) != null &&
5433	>	(reducer = this.reducer) != null) {
5434	>	for (int i = baseIndex, f, h; batch > 0 &&
5435	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5436	>	addToPendingCount(1);
5437	>	(rights = new MapReduceEntriesTask<K,V,U>
5438	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5439	>	rights, transformer, reducer)).fork();
5440	>	}
5441	>	U r = null;
5442	>	for (Node<K,V> p; (p = advance()) != null; ) {
5443	>	U u;
5444	>	if ((u = transformer.apply(p)) != null)
5445	>	r = (r == null) ? u : reducer.apply(r, u);
5446	>	}
5447	>	result = r;
5448	>	CountedCompleter<?> c;
5449	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5450	>	@SuppressWarnings("unchecked") MapReduceEntriesTask<K,V,U>
5451	>	t = (MapReduceEntriesTask<K,V,U>)c,
5452	>	s = t.rights;
5453	>	while (s != null) {
5454	>	U tr, sr;
5455	>	if ((sr = s.result) != null)
5456	>	t.result = (((tr = t.result) == null) ? sr :
5457	>	reducer.apply(tr, sr));
5458	>	s = t.rights = s.nextRight;
5459	>	}
5460	>	}
5461	>	}
5462		}
5463	+	}
5464
5465	<	public V getValue() {
5466	<	return value;
5465	>	@SuppressWarnings("serial")
5466	>	static final class MapReduceMappingsTask<K,V,U>
5467	>	extends BulkTask<K,V,U> {
5468	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5469	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5470	>	U result;
5471	>	MapReduceMappingsTask<K,V,U> rights, nextRight;
5472	>	MapReduceMappingsTask
5473	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5474	>	MapReduceMappingsTask<K,V,U> nextRight,
5475	>	BiFunction<? super K, ? super V, ? extends U> transformer,
5476	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5477	>	super(p, b, i, f, t); this.nextRight = nextRight;
5478	>	this.transformer = transformer;
5479	>	this.reducer = reducer;
5480	>	}
5481	>	public final U getRawResult() { return result; }
5482	>	public final void compute() {
5483	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5484	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5485	>	if ((transformer = this.transformer) != null &&
5486	>	(reducer = this.reducer) != null) {
5487	>	for (int i = baseIndex, f, h; batch > 0 &&
5488	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5489	>	addToPendingCount(1);
5490	>	(rights = new MapReduceMappingsTask<K,V,U>
5491	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5492	>	rights, transformer, reducer)).fork();
5493	>	}
5494	>	U r = null;
5495	>	for (Node<K,V> p; (p = advance()) != null; ) {
5496	>	U u;
5497	>	if ((u = transformer.apply(p.key, p.val)) != null)
5498	>	r = (r == null) ? u : reducer.apply(r, u);
5499	>	}
5500	>	result = r;
5501	>	CountedCompleter<?> c;
5502	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5503	>	@SuppressWarnings("unchecked") MapReduceMappingsTask<K,V,U>
5504	>	t = (MapReduceMappingsTask<K,V,U>)c,
5505	>	s = t.rights;
5506	>	while (s != null) {
5507	>	U tr, sr;
5508	>	if ((sr = s.result) != null)
5509	>	t.result = (((tr = t.result) == null) ? sr :
5510	>	reducer.apply(tr, sr));
5511	>	s = t.rights = s.nextRight;
5512	>	}
5513	>	}
5514	>	}
5515		}
5516	+	}
5517
5518	<	public V setValue(V value) {
5519	<	V oldValue = this.value;
5520	<	this.value = value;
5521	<	return oldValue;
5518	>	@SuppressWarnings("serial")
5519	>	static final class MapReduceKeysToDoubleTask<K,V>
5520	>	extends BulkTask<K,V,Double> {
5521	>	final ToDoubleFunction<? super K> transformer;
5522	>	final DoubleBinaryOperator reducer;
5523	>	final double basis;
5524	>	double result;
5525	>	MapReduceKeysToDoubleTask<K,V> rights, nextRight;
5526	>	MapReduceKeysToDoubleTask
5527	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5528	>	MapReduceKeysToDoubleTask<K,V> nextRight,
5529	>	ToDoubleFunction<? super K> transformer,
5530	>	double basis,
5531	>	DoubleBinaryOperator reducer) {
5532	>	super(p, b, i, f, t); this.nextRight = nextRight;
5533	>	this.transformer = transformer;
5534	>	this.basis = basis; this.reducer = reducer;
5535	>	}
5536	>	public final Double getRawResult() { return result; }
5537	>	public final void compute() {
5538	>	final ToDoubleFunction<? super K> transformer;
5539	>	final DoubleBinaryOperator reducer;
5540	>	if ((transformer = this.transformer) != null &&
5541	>	(reducer = this.reducer) != null) {
5542	>	double r = this.basis;
5543	>	for (int i = baseIndex, f, h; batch > 0 &&
5544	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5545	>	addToPendingCount(1);
5546	>	(rights = new MapReduceKeysToDoubleTask<K,V>
5547	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5548	>	rights, transformer, r, reducer)).fork();
5549	>	}
5550	>	for (Node<K,V> p; (p = advance()) != null; )
5551	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key));
5552	>	result = r;
5553	>	CountedCompleter<?> c;
5554	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5555	>	@SuppressWarnings("unchecked") MapReduceKeysToDoubleTask<K,V>
5556	>	t = (MapReduceKeysToDoubleTask<K,V>)c,
5557	>	s = t.rights;
5558	>	while (s != null) {
5559	>	t.result = reducer.applyAsDouble(t.result, s.result);
5560	>	s = t.rights = s.nextRight;
5561	>	}
5562	>	}
5563	>	}
5564		}
5565	+	}
5566
5567	<	public boolean equals(Object o) {
5568	<	if (!(o instanceof Map.Entry))
5569	<	return false;
5570	<	Map.Entry e = (Map.Entry)o;
5571	<	return eq(key, e.getKey()) && eq(value, e.getValue());
5567	>	@SuppressWarnings("serial")
5568	>	static final class MapReduceValuesToDoubleTask<K,V>
5569	>	extends BulkTask<K,V,Double> {
5570	>	final ToDoubleFunction<? super V> transformer;
5571	>	final DoubleBinaryOperator reducer;
5572	>	final double basis;
5573	>	double result;
5574	>	MapReduceValuesToDoubleTask<K,V> rights, nextRight;
5575	>	MapReduceValuesToDoubleTask
5576	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5577	>	MapReduceValuesToDoubleTask<K,V> nextRight,
5578	>	ToDoubleFunction<? super V> transformer,
5579	>	double basis,
5580	>	DoubleBinaryOperator reducer) {
5581	>	super(p, b, i, f, t); this.nextRight = nextRight;
5582	>	this.transformer = transformer;
5583	>	this.basis = basis; this.reducer = reducer;
5584	>	}
5585	>	public final Double getRawResult() { return result; }
5586	>	public final void compute() {
5587	>	final ToDoubleFunction<? super V> transformer;
5588	>	final DoubleBinaryOperator reducer;
5589	>	if ((transformer = this.transformer) != null &&
5590	>	(reducer = this.reducer) != null) {
5591	>	double r = this.basis;
5592	>	for (int i = baseIndex, f, h; batch > 0 &&
5593	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5594	>	addToPendingCount(1);
5595	>	(rights = new MapReduceValuesToDoubleTask<K,V>
5596	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5597	>	rights, transformer, r, reducer)).fork();
5598	>	}
5599	>	for (Node<K,V> p; (p = advance()) != null; )
5600	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.val));
5601	>	result = r;
5602	>	CountedCompleter<?> c;
5603	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5604	>	@SuppressWarnings("unchecked") MapReduceValuesToDoubleTask<K,V>
5605	>	t = (MapReduceValuesToDoubleTask<K,V>)c,
5606	>	s = t.rights;
5607	>	while (s != null) {
5608	>	t.result = reducer.applyAsDouble(t.result, s.result);
5609	>	s = t.rights = s.nextRight;
5610	>	}
5611	>	}
5612	>	}
5613		}
5614	+	}
5615
5616	<	public int hashCode() {
5617	<	return ((key   == null)   ? 0 :   key.hashCode()) ^
5618	<	((value == null)   ? 0 : value.hashCode());
5616	>	@SuppressWarnings("serial")
5617	>	static final class MapReduceEntriesToDoubleTask<K,V>
5618	>	extends BulkTask<K,V,Double> {
5619	>	final ToDoubleFunction<Map.Entry<K,V>> transformer;
5620	>	final DoubleBinaryOperator reducer;
5621	>	final double basis;
5622	>	double result;
5623	>	MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
5624	>	MapReduceEntriesToDoubleTask
5625	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5626	>	MapReduceEntriesToDoubleTask<K,V> nextRight,
5627	>	ToDoubleFunction<Map.Entry<K,V>> transformer,
5628	>	double basis,
5629	>	DoubleBinaryOperator reducer) {
5630	>	super(p, b, i, f, t); this.nextRight = nextRight;
5631	>	this.transformer = transformer;
5632	>	this.basis = basis; this.reducer = reducer;
5633	>	}
5634	>	public final Double getRawResult() { return result; }
5635	>	public final void compute() {
5636	>	final ToDoubleFunction<Map.Entry<K,V>> transformer;
5637	>	final DoubleBinaryOperator reducer;
5638	>	if ((transformer = this.transformer) != null &&
5639	>	(reducer = this.reducer) != null) {
5640	>	double r = this.basis;
5641	>	for (int i = baseIndex, f, h; batch > 0 &&
5642	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5643	>	addToPendingCount(1);
5644	>	(rights = new MapReduceEntriesToDoubleTask<K,V>
5645	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5646	>	rights, transformer, r, reducer)).fork();
5647	>	}
5648	>	for (Node<K,V> p; (p = advance()) != null; )
5649	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p));
5650	>	result = r;
5651	>	CountedCompleter<?> c;
5652	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5653	>	@SuppressWarnings("unchecked") MapReduceEntriesToDoubleTask<K,V>
5654	>	t = (MapReduceEntriesToDoubleTask<K,V>)c,
5655	>	s = t.rights;
5656	>	while (s != null) {
5657	>	t.result = reducer.applyAsDouble(t.result, s.result);
5658	>	s = t.rights = s.nextRight;
5659	>	}
5660	>	}
5661	>	}
5662		}
5663	+	}
5664
5665	<	public String toString() {
5666	<	return key + "=" + value;
5665	>	@SuppressWarnings("serial")
5666	>	static final class MapReduceMappingsToDoubleTask<K,V>
5667	>	extends BulkTask<K,V,Double> {
5668	>	final ToDoubleBiFunction<? super K, ? super V> transformer;
5669	>	final DoubleBinaryOperator reducer;
5670	>	final double basis;
5671	>	double result;
5672	>	MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
5673	>	MapReduceMappingsToDoubleTask
5674	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5675	>	MapReduceMappingsToDoubleTask<K,V> nextRight,
5676	>	ToDoubleBiFunction<? super K, ? super V> transformer,
5677	>	double basis,
5678	>	DoubleBinaryOperator reducer) {
5679	>	super(p, b, i, f, t); this.nextRight = nextRight;
5680	>	this.transformer = transformer;
5681	>	this.basis = basis; this.reducer = reducer;
5682	>	}
5683	>	public final Double getRawResult() { return result; }
5684	>	public final void compute() {
5685	>	final ToDoubleBiFunction<? super K, ? super V> transformer;
5686	>	final DoubleBinaryOperator reducer;
5687	>	if ((transformer = this.transformer) != null &&
5688	>	(reducer = this.reducer) != null) {
5689	>	double r = this.basis;
5690	>	for (int i = baseIndex, f, h; batch > 0 &&
5691	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5692	>	addToPendingCount(1);
5693	>	(rights = new MapReduceMappingsToDoubleTask<K,V>
5694	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5695	>	rights, transformer, r, reducer)).fork();
5696	>	}
5697	>	for (Node<K,V> p; (p = advance()) != null; )
5698	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key, p.val));
5699	>	result = r;
5700	>	CountedCompleter<?> c;
5701	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5702	>	@SuppressWarnings("unchecked") MapReduceMappingsToDoubleTask<K,V>
5703	>	t = (MapReduceMappingsToDoubleTask<K,V>)c,
5704	>	s = t.rights;
5705	>	while (s != null) {
5706	>	t.result = reducer.applyAsDouble(t.result, s.result);
5707	>	s = t.rights = s.nextRight;
5708	>	}
5709	>	}
5710	>	}
5711		}
5712	+	}
5713
5714	<	static boolean eq(Object o1, Object o2) {
5715	<	return (o1 == null ? o2 == null : o1.equals(o2));
5714	>	@SuppressWarnings("serial")
5715	>	static final class MapReduceKeysToLongTask<K,V>
5716	>	extends BulkTask<K,V,Long> {
5717	>	final ToLongFunction<? super K> transformer;
5718	>	final LongBinaryOperator reducer;
5719	>	final long basis;
5720	>	long result;
5721	>	MapReduceKeysToLongTask<K,V> rights, nextRight;
5722	>	MapReduceKeysToLongTask
5723	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5724	>	MapReduceKeysToLongTask<K,V> nextRight,
5725	>	ToLongFunction<? super K> transformer,
5726	>	long basis,
5727	>	LongBinaryOperator reducer) {
5728	>	super(p, b, i, f, t); this.nextRight = nextRight;
5729	>	this.transformer = transformer;
5730	>	this.basis = basis; this.reducer = reducer;
5731	>	}
5732	>	public final Long getRawResult() { return result; }
5733	>	public final void compute() {
5734	>	final ToLongFunction<? super K> transformer;
5735	>	final LongBinaryOperator reducer;
5736	>	if ((transformer = this.transformer) != null &&
5737	>	(reducer = this.reducer) != null) {
5738	>	long r = this.basis;
5739	>	for (int i = baseIndex, f, h; batch > 0 &&
5740	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5741	>	addToPendingCount(1);
5742	>	(rights = new MapReduceKeysToLongTask<K,V>
5743	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5744	>	rights, transformer, r, reducer)).fork();
5745	>	}
5746	>	for (Node<K,V> p; (p = advance()) != null; )
5747	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.key));
5748	>	result = r;
5749	>	CountedCompleter<?> c;
5750	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5751	>	@SuppressWarnings("unchecked") MapReduceKeysToLongTask<K,V>
5752	>	t = (MapReduceKeysToLongTask<K,V>)c,
5753	>	s = t.rights;
5754	>	while (s != null) {
5755	>	t.result = reducer.applyAsLong(t.result, s.result);
5756	>	s = t.rights = s.nextRight;
5757	>	}
5758	>	}
5759	>	}
5760		}
5761		}
5762
5763	<	/* ---------------- Serialization Support -------------- */
5763	>	@SuppressWarnings("serial")
5764	>	static final class MapReduceValuesToLongTask<K,V>
5765	>	extends BulkTask<K,V,Long> {
5766	>	final ToLongFunction<? super V> transformer;
5767	>	final LongBinaryOperator reducer;
5768	>	final long basis;
5769	>	long result;
5770	>	MapReduceValuesToLongTask<K,V> rights, nextRight;
5771	>	MapReduceValuesToLongTask
5772	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5773	>	MapReduceValuesToLongTask<K,V> nextRight,
5774	>	ToLongFunction<? super V> transformer,
5775	>	long basis,
5776	>	LongBinaryOperator reducer) {
5777	>	super(p, b, i, f, t); this.nextRight = nextRight;
5778	>	this.transformer = transformer;
5779	>	this.basis = basis; this.reducer = reducer;
5780	>	}
5781	>	public final Long getRawResult() { return result; }
5782	>	public final void compute() {
5783	>	final ToLongFunction<? super V> transformer;
5784	>	final LongBinaryOperator reducer;
5785	>	if ((transformer = this.transformer) != null &&
5786	>	(reducer = this.reducer) != null) {
5787	>	long r = this.basis;
5788	>	for (int i = baseIndex, f, h; batch > 0 &&
5789	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5790	>	addToPendingCount(1);
5791	>	(rights = new MapReduceValuesToLongTask<K,V>
5792	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5793	>	rights, transformer, r, reducer)).fork();
5794	>	}
5795	>	for (Node<K,V> p; (p = advance()) != null; )
5796	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.val));
5797	>	result = r;
5798	>	CountedCompleter<?> c;
5799	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5800	>	@SuppressWarnings("unchecked") MapReduceValuesToLongTask<K,V>
5801	>	t = (MapReduceValuesToLongTask<K,V>)c,
5802	>	s = t.rights;
5803	>	while (s != null) {
5804	>	t.result = reducer.applyAsLong(t.result, s.result);
5805	>	s = t.rights = s.nextRight;
5806	>	}
5807	>	}
5808	>	}
5809	>	}
5810	>	}
5811
5812	<	/**
5813	<	* Save the state of the <tt>ConcurrentHashMap</tt>
5814	<	* instance to a stream (i.e.,
5815	<	* serialize it).
5816	<	* @param s the stream
5817	<	* @serialData
5818	<	* the key (Object) and value (Object)
5819	<	* for each key-value mapping, followed by a null pair.
5820	<	* The key-value mappings are emitted in no particular order.
5821	<	*/
5822	<	private void writeObject(java.io.ObjectOutputStream s) throws IOException  {
5823	<	s.defaultWriteObject();
5812	>	@SuppressWarnings("serial")
5813	>	static final class MapReduceEntriesToLongTask<K,V>
5814	>	extends BulkTask<K,V,Long> {
5815	>	final ToLongFunction<Map.Entry<K,V>> transformer;
5816	>	final LongBinaryOperator reducer;
5817	>	final long basis;
5818	>	long result;
5819	>	MapReduceEntriesToLongTask<K,V> rights, nextRight;
5820	>	MapReduceEntriesToLongTask
5821	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5822	>	MapReduceEntriesToLongTask<K,V> nextRight,
5823	>	ToLongFunction<Map.Entry<K,V>> transformer,
5824	>	long basis,
5825	>	LongBinaryOperator reducer) {
5826	>	super(p, b, i, f, t); this.nextRight = nextRight;
5827	>	this.transformer = transformer;
5828	>	this.basis = basis; this.reducer = reducer;
5829	>	}
5830	>	public final Long getRawResult() { return result; }
5831	>	public final void compute() {
5832	>	final ToLongFunction<Map.Entry<K,V>> transformer;
5833	>	final LongBinaryOperator reducer;
5834	>	if ((transformer = this.transformer) != null &&
5835	>	(reducer = this.reducer) != null) {
5836	>	long r = this.basis;
5837	>	for (int i = baseIndex, f, h; batch > 0 &&
5838	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5839	>	addToPendingCount(1);
5840	>	(rights = new MapReduceEntriesToLongTask<K,V>
5841	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5842	>	rights, transformer, r, reducer)).fork();
5843	>	}
5844	>	for (Node<K,V> p; (p = advance()) != null; )
5845	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p));
5846	>	result = r;
5847	>	CountedCompleter<?> c;
5848	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5849	>	@SuppressWarnings("unchecked") MapReduceEntriesToLongTask<K,V>
5850	>	t = (MapReduceEntriesToLongTask<K,V>)c,
5851	>	s = t.rights;
5852	>	while (s != null) {
5853	>	t.result = reducer.applyAsLong(t.result, s.result);
5854	>	s = t.rights = s.nextRight;
5855	>	}
5856	>	}
5857	>	}
5858	>	}
5859	>	}
5860
5861	<	for (int k = 0; k < segments.length; ++k) {
5862	<	Segment<K,V> seg = (Segment<K,V>)segments[k];
5863	<	seg.lock();
5864	<	try {
5865	<	HashEntry[] tab = seg.table;
5866	<	for (int i = 0; i < tab.length; ++i) {
5867	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i]; e != null; e = e.next) {
5868	<	s.writeObject(e.key);
5869	<	s.writeObject(e.value);
5861	>	@SuppressWarnings("serial")
5862	>	static final class MapReduceMappingsToLongTask<K,V>
5863	>	extends BulkTask<K,V,Long> {
5864	>	final ToLongBiFunction<? super K, ? super V> transformer;
5865	>	final LongBinaryOperator reducer;
5866	>	final long basis;
5867	>	long result;
5868	>	MapReduceMappingsToLongTask<K,V> rights, nextRight;
5869	>	MapReduceMappingsToLongTask
5870	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5871	>	MapReduceMappingsToLongTask<K,V> nextRight,
5872	>	ToLongBiFunction<? super K, ? super V> transformer,
5873	>	long basis,
5874	>	LongBinaryOperator reducer) {
5875	>	super(p, b, i, f, t); this.nextRight = nextRight;
5876	>	this.transformer = transformer;
5877	>	this.basis = basis; this.reducer = reducer;
5878	>	}
5879	>	public final Long getRawResult() { return result; }
5880	>	public final void compute() {
5881	>	final ToLongBiFunction<? super K, ? super V> transformer;
5882	>	final LongBinaryOperator reducer;
5883	>	if ((transformer = this.transformer) != null &&
5884	>	(reducer = this.reducer) != null) {
5885	>	long r = this.basis;
5886	>	for (int i = baseIndex, f, h; batch > 0 &&
5887	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5888	>	addToPendingCount(1);
5889	>	(rights = new MapReduceMappingsToLongTask<K,V>
5890	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5891	>	rights, transformer, r, reducer)).fork();
5892	>	}
5893	>	for (Node<K,V> p; (p = advance()) != null; )
5894	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.key, p.val));
5895	>	result = r;
5896	>	CountedCompleter<?> c;
5897	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5898	>	@SuppressWarnings("unchecked") MapReduceMappingsToLongTask<K,V>
5899	>	t = (MapReduceMappingsToLongTask<K,V>)c,
5900	>	s = t.rights;
5901	>	while (s != null) {
5902	>	t.result = reducer.applyAsLong(t.result, s.result);
5903	>	s = t.rights = s.nextRight;
5904		}
5905		}
1384	–	} finally {
1385	–	seg.unlock();
5906		}
5907		}
1388	–	s.writeObject(null);
1389	–	s.writeObject(null);
5908		}
5909
5910	<	/**
5911	<	* Reconstitute the <tt>ConcurrentHashMap</tt>
5912	<	* instance from a stream (i.e.,
5913	<	* deserialize it).
5914	<	* @param s the stream
5915	<	*/
5916	<	private void readObject(java.io.ObjectInputStream s)
5917	<	throws IOException, ClassNotFoundException  {
5918	<	s.defaultReadObject();
5910	>	@SuppressWarnings("serial")
5911	>	static final class MapReduceKeysToIntTask<K,V>
5912	>	extends BulkTask<K,V,Integer> {
5913	>	final ToIntFunction<? super K> transformer;
5914	>	final IntBinaryOperator reducer;
5915	>	final int basis;
5916	>	int result;
5917	>	MapReduceKeysToIntTask<K,V> rights, nextRight;
5918	>	MapReduceKeysToIntTask
5919	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5920	>	MapReduceKeysToIntTask<K,V> nextRight,
5921	>	ToIntFunction<? super K> transformer,
5922	>	int basis,
5923	>	IntBinaryOperator reducer) {
5924	>	super(p, b, i, f, t); this.nextRight = nextRight;
5925	>	this.transformer = transformer;
5926	>	this.basis = basis; this.reducer = reducer;
5927	>	}
5928	>	public final Integer getRawResult() { return result; }
5929	>	public final void compute() {
5930	>	final ToIntFunction<? super K> transformer;
5931	>	final IntBinaryOperator reducer;
5932	>	if ((transformer = this.transformer) != null &&
5933	>	(reducer = this.reducer) != null) {
5934	>	int r = this.basis;
5935	>	for (int i = baseIndex, f, h; batch > 0 &&
5936	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5937	>	addToPendingCount(1);
5938	>	(rights = new MapReduceKeysToIntTask<K,V>
5939	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5940	>	rights, transformer, r, reducer)).fork();
5941	>	}
5942	>	for (Node<K,V> p; (p = advance()) != null; )
5943	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.key));
5944	>	result = r;
5945	>	CountedCompleter<?> c;
5946	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5947	>	@SuppressWarnings("unchecked") MapReduceKeysToIntTask<K,V>
5948	>	t = (MapReduceKeysToIntTask<K,V>)c,
5949	>	s = t.rights;
5950	>	while (s != null) {
5951	>	t.result = reducer.applyAsInt(t.result, s.result);
5952	>	s = t.rights = s.nextRight;
5953	>	}
5954	>	}
5955	>	}
5956	>	}
5957	>	}
5958
5959	<	// Initialize each segment to be minimally sized, and let grow.
5960	<	for (int i = 0; i < segments.length; ++i) {
5961	<	segments[i].setTable(new HashEntry[1]);
5959	>	@SuppressWarnings("serial")
5960	>	static final class MapReduceValuesToIntTask<K,V>
5961	>	extends BulkTask<K,V,Integer> {
5962	>	final ToIntFunction<? super V> transformer;
5963	>	final IntBinaryOperator reducer;
5964	>	final int basis;
5965	>	int result;
5966	>	MapReduceValuesToIntTask<K,V> rights, nextRight;
5967	>	MapReduceValuesToIntTask
5968	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5969	>	MapReduceValuesToIntTask<K,V> nextRight,
5970	>	ToIntFunction<? super V> transformer,
5971	>	int basis,
5972	>	IntBinaryOperator reducer) {
5973	>	super(p, b, i, f, t); this.nextRight = nextRight;
5974	>	this.transformer = transformer;
5975	>	this.basis = basis; this.reducer = reducer;
5976	>	}
5977	>	public final Integer getRawResult() { return result; }
5978	>	public final void compute() {
5979	>	final ToIntFunction<? super V> transformer;
5980	>	final IntBinaryOperator reducer;
5981	>	if ((transformer = this.transformer) != null &&
5982	>	(reducer = this.reducer) != null) {
5983	>	int r = this.basis;
5984	>	for (int i = baseIndex, f, h; batch > 0 &&
5985	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5986	>	addToPendingCount(1);
5987	>	(rights = new MapReduceValuesToIntTask<K,V>
5988	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5989	>	rights, transformer, r, reducer)).fork();
5990	>	}
5991	>	for (Node<K,V> p; (p = advance()) != null; )
5992	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.val));
5993	>	result = r;
5994	>	CountedCompleter<?> c;
5995	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5996	>	@SuppressWarnings("unchecked") MapReduceValuesToIntTask<K,V>
5997	>	t = (MapReduceValuesToIntTask<K,V>)c,
5998	>	s = t.rights;
5999	>	while (s != null) {
6000	>	t.result = reducer.applyAsInt(t.result, s.result);
6001	>	s = t.rights = s.nextRight;
6002	>	}
6003	>	}
6004	>	}
6005		}
6006	+	}
6007
6008	<	// Read the keys and values, and put the mappings in the table
6009	<	for (;;) {
6010	<	K key = (K) s.readObject();
6011	<	V value = (V) s.readObject();
6012	<	if (key == null)
6013	<	break;
6014	<	put(key, value);
6008	>	@SuppressWarnings("serial")
6009	>	static final class MapReduceEntriesToIntTask<K,V>
6010	>	extends BulkTask<K,V,Integer> {
6011	>	final ToIntFunction<Map.Entry<K,V>> transformer;
6012	>	final IntBinaryOperator reducer;
6013	>	final int basis;
6014	>	int result;
6015	>	MapReduceEntriesToIntTask<K,V> rights, nextRight;
6016	>	MapReduceEntriesToIntTask
6017	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6018	>	MapReduceEntriesToIntTask<K,V> nextRight,
6019	>	ToIntFunction<Map.Entry<K,V>> transformer,
6020	>	int basis,
6021	>	IntBinaryOperator reducer) {
6022	>	super(p, b, i, f, t); this.nextRight = nextRight;
6023	>	this.transformer = transformer;
6024	>	this.basis = basis; this.reducer = reducer;
6025	>	}
6026	>	public final Integer getRawResult() { return result; }
6027	>	public final void compute() {
6028	>	final ToIntFunction<Map.Entry<K,V>> transformer;
6029	>	final IntBinaryOperator reducer;
6030	>	if ((transformer = this.transformer) != null &&
6031	>	(reducer = this.reducer) != null) {
6032	>	int r = this.basis;
6033	>	for (int i = baseIndex, f, h; batch > 0 &&
6034	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6035	>	addToPendingCount(1);
6036	>	(rights = new MapReduceEntriesToIntTask<K,V>
6037	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6038	>	rights, transformer, r, reducer)).fork();
6039	>	}
6040	>	for (Node<K,V> p; (p = advance()) != null; )
6041	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p));
6042	>	result = r;
6043	>	CountedCompleter<?> c;
6044	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6045	>	@SuppressWarnings("unchecked") MapReduceEntriesToIntTask<K,V>
6046	>	t = (MapReduceEntriesToIntTask<K,V>)c,
6047	>	s = t.rights;
6048	>	while (s != null) {
6049	>	t.result = reducer.applyAsInt(t.result, s.result);
6050	>	s = t.rights = s.nextRight;
6051	>	}
6052	>	}
6053	>	}
6054	>	}
6055	>	}
6056	>
6057	>	@SuppressWarnings("serial")
6058	>	static final class MapReduceMappingsToIntTask<K,V>
6059	>	extends BulkTask<K,V,Integer> {
6060	>	final ToIntBiFunction<? super K, ? super V> transformer;
6061	>	final IntBinaryOperator reducer;
6062	>	final int basis;
6063	>	int result;
6064	>	MapReduceMappingsToIntTask<K,V> rights, nextRight;
6065	>	MapReduceMappingsToIntTask
6066	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6067	>	MapReduceMappingsToIntTask<K,V> nextRight,
6068	>	ToIntBiFunction<? super K, ? super V> transformer,
6069	>	int basis,
6070	>	IntBinaryOperator reducer) {
6071	>	super(p, b, i, f, t); this.nextRight = nextRight;
6072	>	this.transformer = transformer;
6073	>	this.basis = basis; this.reducer = reducer;
6074	>	}
6075	>	public final Integer getRawResult() { return result; }
6076	>	public final void compute() {
6077	>	final ToIntBiFunction<? super K, ? super V> transformer;
6078	>	final IntBinaryOperator reducer;
6079	>	if ((transformer = this.transformer) != null &&
6080	>	(reducer = this.reducer) != null) {
6081	>	int r = this.basis;
6082	>	for (int i = baseIndex, f, h; batch > 0 &&
6083	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6084	>	addToPendingCount(1);
6085	>	(rights = new MapReduceMappingsToIntTask<K,V>
6086	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6087	>	rights, transformer, r, reducer)).fork();
6088	>	}
6089	>	for (Node<K,V> p; (p = advance()) != null; )
6090	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.key, p.val));
6091	>	result = r;
6092	>	CountedCompleter<?> c;
6093	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6094	>	@SuppressWarnings("unchecked") MapReduceMappingsToIntTask<K,V>
6095	>	t = (MapReduceMappingsToIntTask<K,V>)c,
6096	>	s = t.rights;
6097	>	while (s != null) {
6098	>	t.result = reducer.applyAsInt(t.result, s.result);
6099	>	s = t.rights = s.nextRight;
6100	>	}
6101	>	}
6102	>	}
6103		}
6104		}
1416	–	}
6105
6106	+	// Unsafe mechanics
6107	+	private static final sun.misc.Unsafe U;
6108	+	private static final long SIZECTL;
6109	+	private static final long TRANSFERINDEX;
6110	+	private static final long TRANSFERORIGIN;
6111	+	private static final long BASECOUNT;
6112	+	private static final long CELLSBUSY;
6113	+	private static final long CELLVALUE;
6114	+	private static final long ABASE;
6115	+	private static final int ASHIFT;
6116	+
6117	+	static {
6118	+	try {
6119	+	U = sun.misc.Unsafe.getUnsafe();
6120	+	Class<?> k = ConcurrentHashMap.class;
6121	+	SIZECTL = U.objectFieldOffset
6122	+	(k.getDeclaredField("sizeCtl"));
6123	+	TRANSFERINDEX = U.objectFieldOffset
6124	+	(k.getDeclaredField("transferIndex"));
6125	+	TRANSFERORIGIN = U.objectFieldOffset
6126	+	(k.getDeclaredField("transferOrigin"));
6127	+	BASECOUNT = U.objectFieldOffset
6128	+	(k.getDeclaredField("baseCount"));
6129	+	CELLSBUSY = U.objectFieldOffset
6130	+	(k.getDeclaredField("cellsBusy"));
6131	+	Class<?> ck = CounterCell.class;
6132	+	CELLVALUE = U.objectFieldOffset
6133	+	(ck.getDeclaredField("value"));
6134	+	Class<?> ak = Node[].class;
6135	+	ABASE = U.arrayBaseOffset(ak);
6136	+	int scale = U.arrayIndexScale(ak);
6137	+	if ((scale & (scale - 1)) != 0)
6138	+	throw new Error("data type scale not a power of two");
6139	+	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6140	+	} catch (Exception e) {
6141	+	throw new Error(e);
6142	+	}
6143	+	}
6144	+	}

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