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Comparing jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java (file contents):
Revision 1.52 by dl, Mon Jul 12 11:01:14 2004 UTC vs.
Revision 1.240 by dl, Sat Jul 20 16:50:01 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.ConcurrentModificationException;
18	>	import java.util.Enumeration;
19	>	import java.util.HashMap;
20	>	import java.util.Hashtable;
21	>	import java.util.Iterator;
22	>	import java.util.Map;
23	>	import java.util.NoSuchElementException;
24	>	import java.util.Set;
25	>	import java.util.Spliterator;
26	>	import java.util.concurrent.ConcurrentMap;
27	>	import java.util.concurrent.ForkJoinPool;
28	>	import java.util.concurrent.atomic.AtomicReference;
29	>	import java.util.concurrent.locks.LockSupport;
30	>	import java.util.concurrent.locks.ReentrantLock;
31	>	import java.util.function.BiConsumer;
32	>	import java.util.function.BiFunction;
33	>	import java.util.function.BinaryOperator;
34	>	import java.util.function.Consumer;
35	>	import java.util.function.DoubleBinaryOperator;
36	>	import java.util.function.Function;
37	>	import java.util.function.IntBinaryOperator;
38	>	import java.util.function.LongBinaryOperator;
39	>	import java.util.function.ToDoubleBiFunction;
40	>	import java.util.function.ToDoubleFunction;
41	>	import java.util.function.ToIntBiFunction;
42	>	import java.util.function.ToIntFunction;
43	>	import java.util.function.ToLongBiFunction;
44	>	import java.util.function.ToLongFunction;
45	>	import java.util.stream.Stream;
46
47		/**
48		* A hash table supporting full concurrency of retrievals and
49	<	* adjustable expected concurrency for updates. This class obeys the
49	>	* high expected concurrency for updates. This class obeys the
50		* same functional specification as {@link java.util.Hashtable}, and
51		* includes versions of methods corresponding to each method of
52	<	* <tt>Hashtable</tt>. However, even though all operations are
52	>	* {@code Hashtable}. However, even though all operations are
53		* thread-safe, retrieval operations do <em>not</em> entail locking,
54		* and there is <em>not</em> any support for locking the entire table
55		* in a way that prevents all access.  This class is fully
56	<	* interoperable with <tt>Hashtable</tt> in programs that rely on its
56	>	* interoperable with {@code Hashtable} in programs that rely on its
57		* thread safety but not on its synchronization details.
58		*
59	<	* <p> Retrieval operations (including <tt>get</tt>) generally do not
60	<	* block, so may overlap with update operations (including
61	<	* <tt>put</tt> and <tt>remove</tt>). Retrievals reflect the results
62	<	* of the most recently <em>completed</em> update operations holding
63	<	* upon their onset.  For aggregate operations such as <tt>putAll</tt>
64	<	* and <tt>clear</tt>, concurrent retrievals may reflect insertion or
65	<	* removal of only some entries.  Similarly, Iterators and
66	<	* Enumerations return elements reflecting the state of the hash table
67	<	* at some point at or since the creation of the iterator/enumeration.
68	<	* They do <em>not</em> throw
69	<	* {@link ConcurrentModificationException}.  However, iterators are
70	<	* designed to be used by only one thread at a time.
71	<	*
72	<	* <p> The allowed concurrency among update operations is guided by
73	<	* the optional <tt>concurrencyLevel</tt> constructor argument
74	<	* (default 16), which is used as a hint for internal sizing.  The
75	<	* table is internally partitioned to try to permit the indicated
76	<	* number of concurrent updates without contention. Because placement
77	<	* in hash tables is essentially random, the actual concurrency will
78	<	* vary.  Ideally, you should choose a value to accommodate as many
79	<	* threads as will ever concurrently modify the table. Using a
80	<	* significantly higher value than you need can waste space and time,
81	<	* and a significantly lower value can lead to thread contention. But
82	<	* overestimates and underestimates within an order of magnitude do
83	<	* not usually have much noticeable impact. A value of one is
84	<	* appropriate when it is known that only one thread will modify and
85	<	* all others will only read. Also, resizing this or any other kind of
86	<	* hash table is a relatively slow operation, so, when possible, it is
87	<	* a good idea to provide estimates of expected table sizes in
88	<	* constructors.
59	>	* <p>Retrieval operations (including {@code get}) generally do not
60	>	* block, so may overlap with update operations (including {@code put}
61	>	* and {@code remove}). Retrievals reflect the results of the most
62	>	* recently <em>completed</em> update operations holding upon their
63	>	* onset. (More formally, an update operation for a given key bears a
64	>	* <em>happens-before</em> relation with any (non-null) retrieval for
65	>	* that key reporting the updated value.)  For aggregate operations
66	>	* such as {@code putAll} and {@code clear}, concurrent retrievals may
67	>	* reflect insertion or removal of only some entries.  Similarly,
68	>	* Iterators and Enumerations return elements reflecting the state of
69	>	* the hash table at some point at or since the creation of the
70	>	* iterator/enumeration.  They do <em>not</em> throw {@link
71	>	* ConcurrentModificationException}.  However, iterators are designed
72	>	* to be used by only one thread at a time.  Bear in mind that the
73	>	* results of aggregate status methods including {@code size}, {@code
74	>	* isEmpty}, and {@code containsValue} are typically useful only when
75	>	* a map is not undergoing concurrent updates in other threads.
76	>	* Otherwise the results of these methods reflect transient states
77	>	* that may be adequate for monitoring or estimation purposes, but not
78	>	* for program control.
79	>	*
80	>	* <p>The table is dynamically expanded when there are too many
81	>	* collisions (i.e., keys that have distinct hash codes but fall into
82	>	* the same slot modulo the table size), with the expected average
83	>	* effect of maintaining roughly two bins per mapping (corresponding
84	>	* to a 0.75 load factor threshold for resizing). There may be much
85	>	* variance around this average as mappings are added and removed, but
86	>	* overall, this maintains a commonly accepted time/space tradeoff for
87	>	* hash tables.  However, resizing this or any other kind of hash
88	>	* table may be a relatively slow operation. When possible, it is a
89	>	* good idea to provide a size estimate as an optional {@code
90	>	* initialCapacity} constructor argument. An additional optional
91	>	* {@code loadFactor} constructor argument provides a further means of
92	>	* customizing initial table capacity by specifying the table density
93	>	* to be used in calculating the amount of space to allocate for the
94	>	* given number of elements.  Also, for compatibility with previous
95	>	* versions of this class, constructors may optionally specify an
96	>	* expected {@code concurrencyLevel} as an additional hint for
97	>	* internal sizing.  Note that using many keys with exactly the same
98	>	* {@code hashCode()} is a sure way to slow down performance of any
99	>	* hash table. To ameliorate impact, when keys are {@link Comparable},
100	>	* this class may use comparison order among keys to help break ties.
101	>	*
102	>	* <p>A {@link Set} projection of a ConcurrentHashMap may be created
103	>	* (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed
104	>	* (using {@link #keySet(Object)} when only keys are of interest, and the
105	>	* mapped values are (perhaps transiently) not used or all take the
106	>	* same mapping value.
107	>	*
108	>	* <p>A ConcurrentHashMap can be used as scalable frequency map (a
109	>	* form of histogram or multiset) by using {@link
110	>	* java.util.concurrent.atomic.LongAdder} values and initializing via
111	>	* {@link #computeIfAbsent computeIfAbsent}. For example, to add a count
112	>	* to a {@code ConcurrentHashMap<String,LongAdder> freqs}, you can use
113	>	* {@code freqs.computeIfAbsent(k -> new LongAdder()).increment();}
114		*
115		* <p>This class and its views and iterators implement all of the
116		* <em>optional</em> methods of the {@link Map} and {@link Iterator}
117		* interfaces.
118		*
119	<	* <p> Like {@link java.util.Hashtable} but unlike {@link
120	<	* java.util.HashMap}, this class does NOT allow <tt>null</tt> to be
121	<	* used as a key or value.
119	>	* <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
120	>	* does <em>not</em> allow {@code null} to be used as a key or value.
121	>	*
122	>	* <p>ConcurrentHashMaps support a set of sequential and parallel bulk
123	>	* operations that, unlike most {@link Stream} methods, are designed
124	>	* to be safely, and often sensibly, applied even with maps that are
125	>	* being concurrently updated by other threads; for example, when
126	>	* computing a snapshot summary of the values in a shared registry.
127	>	* There are three kinds of operation, each with four forms, accepting
128	>	* functions with Keys, Values, Entries, and (Key, Value) arguments
129	>	* and/or return values. Because the elements of a ConcurrentHashMap
130	>	* are not ordered in any particular way, and may be processed in
131	>	* different orders in different parallel executions, the correctness
132	>	* of supplied functions should not depend on any ordering, or on any
133	>	* other objects or values that may transiently change while
134	>	* computation is in progress; and except for forEach actions, should
135	>	* ideally be side-effect-free. Bulk operations on {@link java.util.Map.Entry}
136	>	* objects do not support method {@code setValue}.
137	>	*
138	>	* <ul>
139	>	* <li> forEach: Perform a given action on each element.
140	>	* A variant form applies a given transformation on each element
141	>	* before performing the action.</li>
142	>	*
143	>	* <li> search: Return the first available non-null result of
144	>	* applying a given function on each element; skipping further
145	>	* search when a result is found.</li>
146	>	*
147	>	* <li> reduce: Accumulate each element.  The supplied reduction
148	>	* function cannot rely on ordering (more formally, it should be
149	>	* both associative and commutative).  There are five variants:
150	>	*
151	>	* <ul>
152	>	*
153	>	* <li> Plain reductions. (There is not a form of this method for
154	>	* (key, value) function arguments since there is no corresponding
155	>	* return type.)</li>
156	>	*
157	>	* <li> Mapped reductions that accumulate the results of a given
158	>	* function applied to each element.</li>
159	>	*
160	>	* <li> Reductions to scalar doubles, longs, and ints, using a
161	>	* given basis value.</li>
162	>	*
163	>	* </ul>
164	>	* </li>
165	>	* </ul>
166	>	*
167	>	* <p>These bulk operations accept a {@code parallelismThreshold}
168	>	* argument. Methods proceed sequentially if the current map size is
169	>	* estimated to be less than the given threshold. Using a value of
170	>	* {@code Long.MAX_VALUE} suppresses all parallelism.  Using a value
171	>	* of {@code 1} results in maximal parallelism by partitioning into
172	>	* enough subtasks to fully utilize the {@link
173	>	* ForkJoinPool#commonPool()} that is used for all parallel
174	>	* computations. Normally, you would initially choose one of these
175	>	* extreme values, and then measure performance of using in-between
176	>	* values that trade off overhead versus throughput.
177	>	*
178	>	* <p>The concurrency properties of bulk operations follow
179	>	* from those of ConcurrentHashMap: Any non-null result returned
180	>	* from {@code get(key)} and related access methods bears a
181	>	* happens-before relation with the associated insertion or
182	>	* update.  The result of any bulk operation reflects the
183	>	* composition of these per-element relations (but is not
184	>	* necessarily atomic with respect to the map as a whole unless it
185	>	* is somehow known to be quiescent).  Conversely, because keys
186	>	* and values in the map are never null, null serves as a reliable
187	>	* atomic indicator of the current lack of any result.  To
188	>	* maintain this property, null serves as an implicit basis for
189	>	* all non-scalar reduction operations. For the double, long, and
190	>	* int versions, the basis should be one that, when combined with
191	>	* any other value, returns that other value (more formally, it
192	>	* should be the identity element for the reduction). Most common
193	>	* reductions have these properties; for example, computing a sum
194	>	* with basis 0 or a minimum with basis MAX_VALUE.
195	>	*
196	>	* <p>Search and transformation functions provided as arguments
197	>	* should similarly return null to indicate the lack of any result
198	>	* (in which case it is not used). In the case of mapped
199	>	* reductions, this also enables transformations to serve as
200	>	* filters, returning null (or, in the case of primitive
201	>	* specializations, the identity basis) if the element should not
202	>	* be combined. You can create compound transformations and
203	>	* filterings by composing them yourself under this "null means
204	>	* there is nothing there now" rule before using them in search or
205	>	* reduce operations.
206	>	*
207	>	* <p>Methods accepting and/or returning Entry arguments maintain
208	>	* key-value associations. They may be useful for example when
209	>	* finding the key for the greatest value. Note that "plain" Entry
210	>	* arguments can be supplied using {@code new
211	>	* AbstractMap.SimpleEntry(k,v)}.
212	>	*
213	>	* <p>Bulk operations may complete abruptly, throwing an
214	>	* exception encountered in the application of a supplied
215	>	* function. Bear in mind when handling such exceptions that other
216	>	* concurrently executing functions could also have thrown
217	>	* exceptions, or would have done so if the first exception had
218	>	* not occurred.
219	>	*
220	>	* <p>Speedups for parallel compared to sequential forms are common
221	>	* but not guaranteed.  Parallel operations involving brief functions
222	>	* on small maps may execute more slowly than sequential forms if the
223	>	* underlying work to parallelize the computation is more expensive
224	>	* than the computation itself.  Similarly, parallelization may not
225	>	* lead to much actual parallelism if all processors are busy
226	>	* performing unrelated tasks.
227	>	*
228	>	* <p>All arguments to all task methods must be non-null.
229		*
230		* <p>This class is a member of the
231	<	* <a href="{@docRoot}/../guide/collections/index.html">
231	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
232		* Java Collections Framework</a>.
233		*
234		* @since 1.5
235		* @author Doug Lea
236		* @param <K> the type of keys maintained by this map
237	<	* @param <V> the type of mapped values
237	>	* @param <V> the type of mapped values
238		*/
239	<	public class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
240	<	implements ConcurrentMap<K, V>, Serializable {
239	>	public class ConcurrentHashMap<K,V> extends AbstractMap<K,V>
240	>	implements ConcurrentMap<K,V>, Serializable {
241		private static final long serialVersionUID = 7249069246763182397L;
242
243		/*
244	<	* The basic strategy is to subdivide the table among Segments,
245	<	* each of which itself is a concurrently readable hash table.
244	>	* Overview:
245	>	*
246	>	* The primary design goal of this hash table is to maintain
247	>	* concurrent readability (typically method get(), but also
248	>	* iterators and related methods) while minimizing update
249	>	* contention. Secondary goals are to keep space consumption about
250	>	* the same or better than java.util.HashMap, and to support high
251	>	* initial insertion rates on an empty table by many threads.
252	>	*
253	>	* This map usually acts as a binned (bucketed) hash table.  Each
254	>	* key-value mapping is held in a Node.  Most nodes are instances
255	>	* of the basic Node class with hash, key, value, and next
256	>	* fields. However, various subclasses exist: TreeNodes are
257	>	* arranged in balanced trees, not lists.  TreeBins hold the roots
258	>	* of sets of TreeNodes. ForwardingNodes are placed at the heads
259	>	* of bins during resizing. ReservationNodes are used as
260	>	* placeholders while establishing values in computeIfAbsent and
261	>	* related methods.  The types TreeBin, ForwardingNode, and
262	>	* ReservationNode do not hold normal user keys, values, or
263	>	* hashes, and are readily distinguishable during search etc
264	>	* because they have negative hash fields and null key and value
265	>	* fields. (These special nodes are either uncommon or transient,
266	>	* so the impact of carrying around some unused fields is
267	>	* insignificant.)
268	>	*
269	>	* The table is lazily initialized to a power-of-two size upon the
270	>	* first insertion.  Each bin in the table normally contains a
271	>	* list of Nodes (most often, the list has only zero or one Node).
272	>	* Table accesses require volatile/atomic reads, writes, and
273	>	* CASes.  Because there is no other way to arrange this without
274	>	* adding further indirections, we use intrinsics
275	>	* (sun.misc.Unsafe) operations.
276	>	*
277	>	* We use the top (sign) bit of Node hash fields for control
278	>	* purposes -- it is available anyway because of addressing
279	>	* constraints.  Nodes with negative hash fields are specially
280	>	* handled or ignored in map methods.
281	>	*
282	>	* Insertion (via put or its variants) of the first node in an
283	>	* empty bin is performed by just CASing it to the bin.  This is
284	>	* by far the most common case for put operations under most
285	>	* key/hash distributions.  Other update operations (insert,
286	>	* delete, and replace) require locks.  We do not want to waste
287	>	* the space required to associate a distinct lock object with
288	>	* each bin, so instead use the first node of a bin list itself as
289	>	* a lock. Locking support for these locks relies on builtin
290	>	* "synchronized" monitors.
291	>	*
292	>	* Using the first node of a list as a lock does not by itself
293	>	* suffice though: When a node is locked, any update must first
294	>	* validate that it is still the first node after locking it, and
295	>	* retry if not. Because new nodes are always appended to lists,
296	>	* once a node is first in a bin, it remains first until deleted
297	>	* or the bin becomes invalidated (upon resizing).
298	>	*
299	>	* The main disadvantage of per-bin locks is that other update
300	>	* operations on other nodes in a bin list protected by the same
301	>	* lock can stall, for example when user equals() or mapping
302	>	* functions take a long time.  However, statistically, under
303	>	* random hash codes, this is not a common problem.  Ideally, the
304	>	* frequency of nodes in bins follows a Poisson distribution
305	>	* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
306	>	* parameter of about 0.5 on average, given the resizing threshold
307	>	* of 0.75, although with a large variance because of resizing
308	>	* granularity. Ignoring variance, the expected occurrences of
309	>	* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
310	>	* first values are:
311	>	*
312	>	* 0:    0.60653066
313	>	* 1:    0.30326533
314	>	* 2:    0.07581633
315	>	* 3:    0.01263606
316	>	* 4:    0.00157952
317	>	* 5:    0.00015795
318	>	* 6:    0.00001316
319	>	* 7:    0.00000094
320	>	* 8:    0.00000006
321	>	* more: less than 1 in ten million
322	>	*
323	>	* Lock contention probability for two threads accessing distinct
324	>	* elements is roughly 1 / (8 * #elements) under random hashes.
325	>	*
326	>	* Actual hash code distributions encountered in practice
327	>	* sometimes deviate significantly from uniform randomness.  This
328	>	* includes the case when N > (1<<30), so some keys MUST collide.
329	>	* Similarly for dumb or hostile usages in which multiple keys are
330	>	* designed to have identical hash codes or ones that differs only
331	>	* in masked-out high bits. So we use a secondary strategy that
332	>	* applies when the number of nodes in a bin exceeds a
333	>	* threshold. These TreeBins use a balanced tree to hold nodes (a
334	>	* specialized form of red-black trees), bounding search time to
335	>	* O(log N).  Each search step in a TreeBin is at least twice as
336	>	* slow as in a regular list, but given that N cannot exceed
337	>	* (1<<64) (before running out of addresses) this bounds search
338	>	* steps, lock hold times, etc, to reasonable constants (roughly
339	>	* 100 nodes inspected per operation worst case) so long as keys
340	>	* are Comparable (which is very common -- String, Long, etc).
341	>	* TreeBin nodes (TreeNodes) also maintain the same "next"
342	>	* traversal pointers as regular nodes, so can be traversed in
343	>	* iterators in the same way.
344	>	*
345	>	* The table is resized when occupancy exceeds a percentage
346	>	* threshold (nominally, 0.75, but see below).  Any thread
347	>	* noticing an overfull bin may assist in resizing after the
348	>	* initiating thread allocates and sets up the replacement
349	>	* array. However, rather than stalling, these other threads may
350	>	* proceed with insertions etc.  The use of TreeBins shields us
351	>	* from the worst case effects of overfilling while resizes are in
352	>	* progress.  Resizing proceeds by transferring bins, one by one,
353	>	* from the table to the next table. To enable concurrency, the
354	>	* next table must be (incrementally) prefilled with place-holders
355	>	* serving as reverse forwarders to the old table.  Because we are
356	>	* using power-of-two expansion, the elements from each bin must
357	>	* either stay at same index, or move with a power of two
358	>	* offset. We eliminate unnecessary node creation by catching
359	>	* cases where old nodes can be reused because their next fields
360	>	* won't change.  On average, only about one-sixth of them need
361	>	* cloning when a table doubles. The nodes they replace will be
362	>	* garbage collectable as soon as they are no longer referenced by
363	>	* any reader thread that may be in the midst of concurrently
364	>	* traversing table.  Upon transfer, the old table bin contains
365	>	* only a special forwarding node (with hash field "MOVED") that
366	>	* contains the next table as its key. On encountering a
367	>	* forwarding node, access and update operations restart, using
368	>	* the new table.
369	>	*
370	>	* Each bin transfer requires its bin lock, which can stall
371	>	* waiting for locks while resizing. However, because other
372	>	* threads can join in and help resize rather than contend for
373	>	* locks, average aggregate waits become shorter as resizing
374	>	* progresses.  The transfer operation must also ensure that all
375	>	* accessible bins in both the old and new table are usable by any
376	>	* traversal.  This is arranged by proceeding from the last bin
377	>	* (table.length - 1) up towards the first.  Upon seeing a
378	>	* forwarding node, traversals (see class Traverser) arrange to
379	>	* move to the new table without revisiting nodes.  However, to
380	>	* ensure that no intervening nodes are skipped, bin splitting can
381	>	* only begin after the associated reverse-forwarders are in
382	>	* place.
383	>	*
384	>	* The traversal scheme also applies to partial traversals of
385	>	* ranges of bins (via an alternate Traverser constructor)
386	>	* to support partitioned aggregate operations.  Also, read-only
387	>	* operations give up if ever forwarded to a null table, which
388	>	* provides support for shutdown-style clearing, which is also not
389	>	* currently implemented.
390	>	*
391	>	* Lazy table initialization minimizes footprint until first use,
392	>	* and also avoids resizings when the first operation is from a
393	>	* putAll, constructor with map argument, or deserialization.
394	>	* These cases attempt to override the initial capacity settings,
395	>	* but harmlessly fail to take effect in cases of races.
396	>	*
397	>	* The element count is maintained using a specialization of
398	>	* LongAdder. We need to incorporate a specialization rather than
399	>	* just use a LongAdder in order to access implicit
400	>	* contention-sensing that leads to creation of multiple
401	>	* CounterCells.  The counter mechanics avoid contention on
402	>	* updates but can encounter cache thrashing if read too
403	>	* frequently during concurrent access. To avoid reading so often,
404	>	* resizing under contention is attempted only upon adding to a
405	>	* bin already holding two or more nodes. Under uniform hash
406	>	* distributions, the probability of this occurring at threshold
407	>	* is around 13%, meaning that only about 1 in 8 puts check
408	>	* threshold (and after resizing, many fewer do so).
409	>	*
410	>	* TreeBins use a special form of comparison for search and
411	>	* related operations (which is the main reason we cannot use
412	>	* existing collections such as TreeMaps). TreeBins contain
413	>	* Comparable elements, but may contain others, as well as
414	>	* elements that are Comparable but not necessarily Comparable for
415	>	* the same T, so we cannot invoke compareTo among them. To handle
416	>	* this, the tree is ordered primarily by hash value, then by
417	>	* Comparable.compareTo order if applicable.  On lookup at a node,
418	>	* if elements are not comparable or compare as 0 then both left
419	>	* and right children may need to be searched in the case of tied
420	>	* hash values. (This corresponds to the full list search that
421	>	* would be necessary if all elements were non-Comparable and had
422	>	* tied hashes.) On insertion, to keep a total ordering (or as
423	>	* close as is required here) across rebalancings, we compare
424	>	* classes and identityHashCodes as tie-breakers. The red-black
425	>	* balancing code is updated from pre-jdk-collections
426	>	* (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
427	>	* based in turn on Cormen, Leiserson, and Rivest "Introduction to
428	>	* Algorithms" (CLR).
429	>	*
430	>	* TreeBins also require an additional locking mechanism.  While
431	>	* list traversal is always possible by readers even during
432	>	* updates, tree traversal is not, mainly because of tree-rotations
433	>	* that may change the root node and/or its linkages.  TreeBins
434	>	* include a simple read-write lock mechanism parasitic on the
435	>	* main bin-synchronization strategy: Structural adjustments
436	>	* associated with an insertion or removal are already bin-locked
437	>	* (and so cannot conflict with other writers) but must wait for
438	>	* ongoing readers to finish. Since there can be only one such
439	>	* waiter, we use a simple scheme using a single "waiter" field to
440	>	* block writers.  However, readers need never block.  If the root
441	>	* lock is held, they proceed along the slow traversal path (via
442	>	* next-pointers) until the lock becomes available or the list is
443	>	* exhausted, whichever comes first. These cases are not fast, but
444	>	* maximize aggregate expected throughput.
445	>	*
446	>	* Maintaining API and serialization compatibility with previous
447	>	* versions of this class introduces several oddities. Mainly: We
448	>	* leave untouched but unused constructor arguments refering to
449	>	* concurrencyLevel. We accept a loadFactor constructor argument,
450	>	* but apply it only to initial table capacity (which is the only
451	>	* time that we can guarantee to honor it.) We also declare an
452	>	* unused "Segment" class that is instantiated in minimal form
453	>	* only when serializing.
454	>	*
455	>	* Also, solely for compatibility with previous versions of this
456	>	* class, it extends AbstractMap, even though all of its methods
457	>	* are overridden, so it is just useless baggage.
458	>	*
459	>	* This file is organized to make things a little easier to follow
460	>	* while reading than they might otherwise: First the main static
461	>	* declarations and utilities, then fields, then main public
462	>	* methods (with a few factorings of multiple public methods into
463	>	* internal ones), then sizing methods, trees, traversers, and
464	>	* bulk operations.
465		*/
466
467		/* ---------------- Constants -------------- */
468
469		/**
470	<	* The default initial number of table slots for this table.
471	<	* Used when not otherwise specified in constructor.
470	>	* The largest possible table capacity.  This value must be
471	>	* exactly 1<<30 to stay within Java array allocation and indexing
472	>	* bounds for power of two table sizes, and is further required
473	>	* because the top two bits of 32bit hash fields are used for
474	>	* control purposes.
475		*/
476	<	static int DEFAULT_INITIAL_CAPACITY = 16;
476	>	private static final int MAXIMUM_CAPACITY = 1 << 30;
477
478		/**
479	<	* The maximum capacity, used if a higher value is implicitly
480	<	* 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.
479	>	* The default initial table capacity.  Must be a power of 2
480	>	* (i.e., at least 1) and at most MAXIMUM_CAPACITY.
481		*/
482	<	static final int MAXIMUM_CAPACITY = 1 << 30;
482	>	private static final int DEFAULT_CAPACITY = 16;
483
484		/**
485	<	* The default load factor for this table.  Used when not
486	<	* otherwise specified in constructor.
485	>	* The largest possible (non-power of two) array size.
486	>	* Needed by toArray and related methods.
487		*/
488	<	static final float DEFAULT_LOAD_FACTOR = 0.75f;
488	>	static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
489
490		/**
491	<	* The default number of concurrency control segments.
492	<	**/
493	<	static final int DEFAULT_SEGMENTS = 16;
491	>	* The default concurrency level for this table. Unused but
492	>	* defined for compatibility with previous versions of this class.
493	>	*/
494	>	private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
495
496		/**
497	<	* The maximum number of segments to allow; used to bound
498	<	* constructor arguments.
497	>	* The load factor for this table. Overrides of this value in
498	>	* constructors affect only the initial table capacity.  The
499	>	* actual floating point value isn't normally used -- it is
500	>	* simpler to use expressions such as {@code n - (n >>> 2)} for
501	>	* the associated resizing threshold.
502		*/
503	<	static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
503	>	private static final float LOAD_FACTOR = 0.75f;
504
505		/**
506	<	* Number of unsynchronized retries in size and containsValue
507	<	* methods before resorting to locking. This is used to avoid
508	<	* unbounded retries if tables undergo continuous modification
509	<	* which would make it impossible to obtain an accurate result.
506	>	* The bin count threshold for using a tree rather than list for a
507	>	* bin.  Bins are converted to trees when adding an element to a
508	>	* bin with at least this many nodes. The value must be greater
509	>	* than 2, and should be at least 8 to mesh with assumptions in
510	>	* tree removal about conversion back to plain bins upon
511	>	* shrinkage.
512		*/
513	<	static final int RETRIES_BEFORE_LOCK = 2;
513	>	static final int TREEIFY_THRESHOLD = 8;
514
515	<	/* ---------------- Fields -------------- */
515	>	/**
516	>	* The bin count threshold for untreeifying a (split) bin during a
517	>	* resize operation. Should be less than TREEIFY_THRESHOLD, and at
518	>	* most 6 to mesh with shrinkage detection under removal.
519	>	*/
520	>	static final int UNTREEIFY_THRESHOLD = 6;
521
522		/**
523	<	* Mask value for indexing into segments. The upper bits of a
524	<	* key's hash code are used to choose the segment.
525	<	**/
526	<	final int segmentMask;
523	>	* The smallest table capacity for which bins may be treeified.
524	>	* (Otherwise the table is resized if too many nodes in a bin.)
525	>	* The value should be at least 4 * TREEIFY_THRESHOLD to avoid
526	>	* conflicts between resizing and treeification thresholds.
527	>	*/
528	>	static final int MIN_TREEIFY_CAPACITY = 64;
529
530		/**
531	<	* Shift value for indexing within segments.
532	<	**/
533	<	final int segmentShift;
531	>	* Minimum number of rebinnings per transfer step. Ranges are
532	>	* subdivided to allow multiple resizer threads.  This value
533	>	* serves as a lower bound to avoid resizers encountering
534	>	* excessive memory contention.  The value should be at least
535	>	* DEFAULT_CAPACITY.
536	>	*/
537	>	private static final int MIN_TRANSFER_STRIDE = 16;
538	>
539	>	/*
540	>	* Encodings for Node hash fields. See above for explanation.
541	>	*/
542	>	static final int MOVED     = -1; // hash for forwarding nodes
543	>	static final int TREEBIN   = -2; // hash for roots of trees
544	>	static final int RESERVED  = -3; // hash for transient reservations
545	>	static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
546	>
547	>	/** Number of CPUS, to place bounds on some sizings */
548	>	static final int NCPU = Runtime.getRuntime().availableProcessors();
549	>
550	>	/** For serialization compatibility. */
551	>	private static final ObjectStreamField[] serialPersistentFields = {
552	>	new ObjectStreamField("segments", Segment[].class),
553	>	new ObjectStreamField("segmentMask", Integer.TYPE),
554	>	new ObjectStreamField("segmentShift", Integer.TYPE)
555	>	};
556	>
557	>	/* ---------------- Nodes -------------- */
558
559		/**
560	<	* The segments, each of which is a specialized hash table
560	>	* Key-value entry.  This class is never exported out as a
561	>	* user-mutable Map.Entry (i.e., one supporting setValue; see
562	>	* MapEntry below), but can be used for read-only traversals used
563	>	* in bulk tasks.  Subclasses of Node with a negative hash field
564	>	* are special, and contain null keys and values (but are never
565	>	* exported).  Otherwise, keys and vals are never null.
566		*/
567	<	final Segment[] segments;
567	>	static class Node<K,V> implements Map.Entry<K,V> {
568	>	final int hash;
569	>	final K key;
570	>	volatile V val;
571	>	volatile Node<K,V> next;
572
573	<	transient Set<K> keySet;
574	<	transient Set<Map.Entry<K,V>> entrySet;
575	<	transient Collection<V> values;
573	>	Node(int hash, K key, V val, Node<K,V> next) {
574	>	this.hash = hash;
575	>	this.key = key;
576	>	this.val = val;
577	>	this.next = next;
578	>	}
579	>
580	>	public final K getKey()       { return key; }
581	>	public final V getValue()     { return val; }
582	>	public final int hashCode()   { return key.hashCode() ^ val.hashCode(); }
583	>	public final String toString(){ return key + "=" + val; }
584	>	public final V setValue(V value) {
585	>	throw new UnsupportedOperationException();
586	>	}
587	>
588	>	public final boolean equals(Object o) {
589	>	Object k, v, u; Map.Entry<?,?> e;
590	>	return ((o instanceof Map.Entry) &&
591	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
592	>	(v = e.getValue()) != null &&
593	>	(k == key || k.equals(key)) &&
594	>	(v == (u = val) || v.equals(u)));
595	>	}
596	>
597	>	/**
598	>	* Virtualized support for map.get(); overridden in subclasses.
599	>	*/
600	>	Node<K,V> find(int h, Object k) {
601	>	Node<K,V> e = this;
602	>	if (k != null) {
603	>	do {
604	>	K ek;
605	>	if (e.hash == h &&
606	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
607	>	return e;
608	>	} while ((e = e.next) != null);
609	>	}
610	>	return null;
611	>	}
612	>	}
613
614	<	/* ---------------- Small Utilities -------------- */
614	>	/* ---------------- Static utilities -------------- */
615
616		/**
617	<	* Returns a hash code for non-null Object x.
618	<	* Uses the same hash code spreader as most other java.util hash tables.
619	<	* @param x the object serving as a key
620	<	* @return the hash code
617	>	* Spreads (XORs) higher bits of hash to lower and also forces top
618	>	* bit to 0. Because the table uses power-of-two masking, sets of
619	>	* hashes that vary only in bits above the current mask will
620	>	* always collide. (Among known examples are sets of Float keys
621	>	* holding consecutive whole numbers in small tables.)  So we
622	>	* apply a transform that spreads the impact of higher bits
623	>	* downward. There is a tradeoff between speed, utility, and
624	>	* quality of bit-spreading. Because many common sets of hashes
625	>	* are already reasonably distributed (so don't benefit from
626	>	* spreading), and because we use trees to handle large sets of
627	>	* collisions in bins, we just XOR some shifted bits in the
628	>	* cheapest possible way to reduce systematic lossage, as well as
629	>	* to incorporate impact of the highest bits that would otherwise
630	>	* never be used in index calculations because of table bounds.
631		*/
632	<	static int hash(Object x) {
633	<	int h = x.hashCode();
157	<	h += ~(h << 9);
158	<	h ^=  (h >>> 14);
159	<	h +=  (h << 4);
160	<	h ^=  (h >>> 10);
161	<	return h;
632	>	static final int spread(int h) {
633	>	return (h ^ (h >>> 16)) & HASH_BITS;
634		}
635
636		/**
637	<	* Returns the segment that should be used for key with given hash
638	<	* @param hash the hash code for the key
167	<	* @return the segment
637	>	* Returns a power of two table size for the given desired capacity.
638	>	* See Hackers Delight, sec 3.2
639		*/
640	<	final Segment<K,V> segmentFor(int hash) {
641	<	return (Segment<K,V>) segments[(hash >>> segmentShift) & segmentMask];
640	>	private static final int tableSizeFor(int c) {
641	>	int n = c - 1;
642	>	n |= n >>> 1;
643	>	n |= n >>> 2;
644	>	n |= n >>> 4;
645	>	n |= n >>> 8;
646	>	n |= n >>> 16;
647	>	return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
648		}
649
650	<	/* ---------------- Inner Classes -------------- */
650	>	/**
651	>	* Returns x's Class if it is of the form "class C implements
652	>	* Comparable<C>", else null.
653	>	*/
654	>	static Class<?> comparableClassFor(Object x) {
655	>	if (x instanceof Comparable) {
656	>	Class<?> c; Type[] ts, as; Type t; ParameterizedType p;
657	>	if ((c = x.getClass()) == String.class) // bypass checks
658	>	return c;
659	>	if ((ts = c.getGenericInterfaces()) != null) {
660	>	for (int i = 0; i < ts.length; ++i) {
661	>	if (((t = ts[i]) instanceof ParameterizedType) &&
662	>	((p = (ParameterizedType)t).getRawType() ==
663	>	Comparable.class) &&
664	>	(as = p.getActualTypeArguments()) != null &&
665	>	as.length == 1 && as[0] == c) // type arg is c
666	>	return c;
667	>	}
668	>	}
669	>	}
670	>	return null;
671	>	}
672
673		/**
674	<	* ConcurrentHashMap list entry. Note that this is never exported
675	<	* 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.
674	>	* Returns k.compareTo(x) if x matches kc (k's screened comparable
675	>	* class), else 0.
676		*/
677	<	static final class HashEntry<K,V> {
678	<	final K key;
679	<	final int hash;
680	<	volatile V value;
681	<	final HashEntry<K,V> next;
677	>	@SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
678	>	static int compareComparables(Class<?> kc, Object k, Object x) {
679	>	return (x == null || x.getClass() != kc ? 0 :
680	>	((Comparable)k).compareTo(x));
681	>	}
682
683	<	HashEntry(K key, int hash, HashEntry<K,V> next, V value) {
684	<	this.key = key;
685	<	this.hash = hash;
686	<	this.next = next;
687	<	this.value = value;
688	<	}
683	>	/* ---------------- Table element access -------------- */
684	>
685	>	/*
686	>	* Volatile access methods are used for table elements as well as
687	>	* elements of in-progress next table while resizing.  All uses of
688	>	* the tab arguments must be null checked by callers.  All callers
689	>	* also paranoically precheck that tab's length is not zero (or an
690	>	* equivalent check), thus ensuring that any index argument taking
691	>	* the form of a hash value anded with (length - 1) is a valid
692	>	* index.  Note that, to be correct wrt arbitrary concurrency
693	>	* errors by users, these checks must operate on local variables,
694	>	* which accounts for some odd-looking inline assignments below.
695	>	* Note that calls to setTabAt always occur within locked regions,
696	>	* and so in principle require only release ordering, not need
697	>	* full volatile semantics, but are currently coded as volatile
698	>	* writes to be conservative.
699	>	*/
700	>
701	>	@SuppressWarnings("unchecked")
702	>	static final <K,V> Node<K,V> tabAt(Node<K,V>[] tab, int i) {
703	>	return (Node<K,V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
704	>	}
705	>
706	>	static final <K,V> boolean casTabAt(Node<K,V>[] tab, int i,
707	>	Node<K,V> c, Node<K,V> v) {
708	>	return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
709		}
710
711	+	static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {
712	+	U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
713	+	}
714	+
715	+	/* ---------------- Fields -------------- */
716	+
717		/**
718	<	* Segments are specialized versions of hash tables.  This
719	<	* subclasses from ReentrantLock opportunistically, just to
720	<	* simplify some locking and avoid separate construction.
721	<	**/
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	<	*/
718	>	* The array of bins. Lazily initialized upon first insertion.
719	>	* Size is always a power of two. Accessed directly by iterators.
720	>	*/
721	>	transient volatile Node<K,V>[] table;
722
723	<	private static final long serialVersionUID = 2249069246763182397L;
723	>	/**
724	>	* The next table to use; non-null only while resizing.
725	>	*/
726	>	private transient volatile Node<K,V>[] nextTable;
727
728	<	/**
729	<	* The number of elements in this segment's region.
730	<	**/
731	<	transient volatile int count;
728	>	/**
729	>	* Base counter value, used mainly when there is no contention,
730	>	* but also as a fallback during table initialization
731	>	* races. Updated via CAS.
732	>	*/
733	>	private transient volatile long baseCount;
734
735	<	/**
736	<	* Number of updates that alter the size of the table. This is
737	<	* used during bulk-read methods to make sure they see a
738	<	* consistent snapshot: If modCounts change during a traversal
739	<	* of segments computing size or checking containsValue, then
740	<	* we might have an inconsistent view of state so (usually)
741	<	* must retry.
742	<	*/
743	<	transient int modCount;
735	>	/**
736	>	* Table initialization and resizing control.  When negative, the
737	>	* table is being initialized or resized: -1 for initialization,
738	>	* else -(1 + the number of active resizing threads).  Otherwise,
739	>	* when table is null, holds the initial table size to use upon
740	>	* creation, or 0 for default. After initialization, holds the
741	>	* next element count value upon which to resize the table.
742	>	*/
743	>	private transient volatile int sizeCtl;
744
745	<	/**
746	<	* The table is rehashed when its size exceeds this threshold.
747	<	* (The value of this field is always (int)(capacity *
748	<	* loadFactor).)
265	<	*/
266	<	transient int threshold;
745	>	/**
746	>	* The next table index (plus one) to split while resizing.
747	>	*/
748	>	private transient volatile int transferIndex;
749
750	<	/**
751	<	* The per-segment table. Declared as a raw type, casted
752	<	* to HashEntry<K,V> on each use.
753	<	*/
272	<	transient volatile HashEntry[] table;
750	>	/**
751	>	* The least available table index to split while resizing.
752	>	*/
753	>	private transient volatile int transferOrigin;
754
755	<	/**
756	<	* The load factor for the hash table.  Even though this value
757	<	* is same for all segments, it is replicated to avoid needing
758	<	* links to outer object.
278	<	* @serial
279	<	*/
280	<	final float loadFactor;
755	>	/**
756	>	* Spinlock (locked via CAS) used when resizing and/or creating CounterCells.
757	>	*/
758	>	private transient volatile int cellsBusy;
759
760	<	Segment(int initialCapacity, float lf) {
761	<	loadFactor = lf;
762	<	setTable(new HashEntry[initialCapacity]);
763	<	}
760	>	/**
761	>	* Table of counter cells. When non-null, size is a power of 2.
762	>	*/
763	>	private transient volatile CounterCell[] counterCells;
764
765	<	/**
766	<	* Set table to new HashEntry array.
767	<	* Call only while holding lock or in constructor.
768	<	**/
291	<	void setTable(HashEntry[] newTable) {
292	<	threshold = (int)(newTable.length * loadFactor);
293	<	table = newTable;
294	<	}
765	>	// views
766	>	private transient KeySetView<K,V> keySet;
767	>	private transient ValuesView<K,V> values;
768	>	private transient EntrySetView<K,V> entrySet;
769
770	<	/**
771	<	* Return properly casted first entry of bin for given hash
772	<	*/
773	<	HashEntry<K,V> getFirst(int hash) {
774	<	HashEntry[] tab = table;
775	<	return (HashEntry<K,V>) tab[hash & (tab.length - 1)];
770	>
771	>	/* ---------------- Public operations -------------- */
772	>
773	>	/**
774	>	* Creates a new, empty map with the default initial table size (16).
775	>	*/
776	>	public ConcurrentHashMap() {
777	>	}
778	>
779	>	/**
780	>	* Creates a new, empty map with an initial table size
781	>	* accommodating the specified number of elements without the need
782	>	* to dynamically resize.
783	>	*
784	>	* @param initialCapacity The implementation performs internal
785	>	* sizing to accommodate this many elements.
786	>	* @throws IllegalArgumentException if the initial capacity of
787	>	* elements is negative
788	>	*/
789	>	public ConcurrentHashMap(int initialCapacity) {
790	>	if (initialCapacity < 0)
791	>	throw new IllegalArgumentException();
792	>	int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ?
793	>	MAXIMUM_CAPACITY :
794	>	tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
795	>	this.sizeCtl = cap;
796	>	}
797	>
798	>	/**
799	>	* Creates a new map with the same mappings as the given map.
800	>	*
801	>	* @param m the map
802	>	*/
803	>	public ConcurrentHashMap(Map<? extends K, ? extends V> m) {
804	>	this.sizeCtl = DEFAULT_CAPACITY;
805	>	putAll(m);
806	>	}
807	>
808	>	/**
809	>	* Creates a new, empty map with an initial table size based on
810	>	* the given number of elements ({@code initialCapacity}) and
811	>	* initial table density ({@code loadFactor}).
812	>	*
813	>	* @param initialCapacity the initial capacity. The implementation
814	>	* performs internal sizing to accommodate this many elements,
815	>	* given the specified load factor.
816	>	* @param loadFactor the load factor (table density) for
817	>	* establishing the initial table size
818	>	* @throws IllegalArgumentException if the initial capacity of
819	>	* elements is negative or the load factor is nonpositive
820	>	*
821	>	* @since 1.6
822	>	*/
823	>	public ConcurrentHashMap(int initialCapacity, float loadFactor) {
824	>	this(initialCapacity, loadFactor, 1);
825	>	}
826	>
827	>	/**
828	>	* Creates a new, empty map with an initial table size based on
829	>	* the given number of elements ({@code initialCapacity}), table
830	>	* density ({@code loadFactor}), and number of concurrently
831	>	* updating threads ({@code concurrencyLevel}).
832	>	*
833	>	* @param initialCapacity the initial capacity. The implementation
834	>	* performs internal sizing to accommodate this many elements,
835	>	* given the specified load factor.
836	>	* @param loadFactor the load factor (table density) for
837	>	* establishing the initial table size
838	>	* @param concurrencyLevel the estimated number of concurrently
839	>	* updating threads. The implementation may use this value as
840	>	* a sizing hint.
841	>	* @throws IllegalArgumentException if the initial capacity is
842	>	* negative or the load factor or concurrencyLevel are
843	>	* nonpositive
844	>	*/
845	>	public ConcurrentHashMap(int initialCapacity,
846	>	float loadFactor, int concurrencyLevel) {
847	>	if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
848	>	throw new IllegalArgumentException();
849	>	if (initialCapacity < concurrencyLevel)   // Use at least as many bins
850	>	initialCapacity = concurrencyLevel;   // as estimated threads
851	>	long size = (long)(1.0 + (long)initialCapacity / loadFactor);
852	>	int cap = (size >= (long)MAXIMUM_CAPACITY) ?
853	>	MAXIMUM_CAPACITY : tableSizeFor((int)size);
854	>	this.sizeCtl = cap;
855	>	}
856	>
857	>	// Original (since JDK1.2) Map methods
858	>
859	>	/**
860	>	* {@inheritDoc}
861	>	*/
862	>	public int size() {
863	>	long n = sumCount();
864	>	return ((n < 0L) ? 0 :
865	>	(n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
866	>	(int)n);
867	>	}
868	>
869	>	/**
870	>	* {@inheritDoc}
871	>	*/
872	>	public boolean isEmpty() {
873	>	return sumCount() <= 0L; // ignore transient negative values
874	>	}
875	>
876	>	/**
877	>	* Returns the value to which the specified key is mapped,
878	>	* or {@code null} if this map contains no mapping for the key.
879	>	*
880	>	* <p>More formally, if this map contains a mapping from a key
881	>	* {@code k} to a value {@code v} such that {@code key.equals(k)},
882	>	* then this method returns {@code v}; otherwise it returns
883	>	* {@code null}.  (There can be at most one such mapping.)
884	>	*
885	>	* @throws NullPointerException if the specified key is null
886	>	*/
887	>	public V get(Object key) {
888	>	Node<K,V>[] tab; Node<K,V> e, p; int n, eh; K ek;
889	>	int h = spread(key.hashCode());
890	>	if ((tab = table) != null && (n = tab.length) > 0 &&
891	>	(e = tabAt(tab, (n - 1) & h)) != null) {
892	>	if ((eh = e.hash) == h) {
893	>	if ((ek = e.key) == key || (ek != null && key.equals(ek)))
894	>	return e.val;
895	>	}
896	>	else if (eh < 0)
897	>	return (p = e.find(h, key)) != null ? p.val : null;
898	>	while ((e = e.next) != null) {
899	>	if (e.hash == h &&
900	>	((ek = e.key) == key || (ek != null && key.equals(ek))))
901	>	return e.val;
902	>	}
903		}
904	+	return null;
905	+	}
906
907	<	/**
908	<	* Read value field of an entry under lock. Called if value
909	<	* field ever appears to be null. This is possible only if a
910	<	* compiler happens to reorder a HashEntry initialization with
911	<	* its table assignment, which is legal under memory model
912	<	* but is not known to ever occur.
913	<	*/
914	<	V readValueUnderLock(HashEntry<K,V> e) {
915	<	lock();
916	<	try {
917	<	return e.value;
918	<	} finally {
919	<	unlock();
907	>	/**
908	>	* Tests if the specified object is a key in this table.
909	>	*
910	>	* @param  key possible key
911	>	* @return {@code true} if and only if the specified object
912	>	*         is a key in this table, as determined by the
913	>	*         {@code equals} method; {@code false} otherwise
914	>	* @throws NullPointerException if the specified key is null
915	>	*/
916	>	public boolean containsKey(Object key) {
917	>	return get(key) != null;
918	>	}
919	>
920	>	/**
921	>	* Returns {@code true} if this map maps one or more keys to the
922	>	* specified value. Note: This method may require a full traversal
923	>	* of the map, and is much slower than method {@code containsKey}.
924	>	*
925	>	* @param value value whose presence in this map is to be tested
926	>	* @return {@code true} if this map maps one or more keys to the
927	>	*         specified value
928	>	* @throws NullPointerException if the specified value is null
929	>	*/
930	>	public boolean containsValue(Object value) {
931	>	if (value == null)
932	>	throw new NullPointerException();
933	>	Node<K,V>[] t;
934	>	if ((t = table) != null) {
935	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
936	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
937	>	V v;
938	>	if ((v = p.val) == value || (v != null && value.equals(v)))
939	>	return true;
940		}
941		}
942	+	return false;
943	+	}
944
945	<	/* Specialized implementations of map methods */
945	>	/**
946	>	* Maps the specified key to the specified value in this table.
947	>	* Neither the key nor the value can be null.
948	>	*
949	>	* <p>The value can be retrieved by calling the {@code get} method
950	>	* with a key that is equal to the original key.
951	>	*
952	>	* @param key key with which the specified value is to be associated
953	>	* @param value value to be associated with the specified key
954	>	* @return the previous value associated with {@code key}, or
955	>	*         {@code null} if there was no mapping for {@code key}
956	>	* @throws NullPointerException if the specified key or value is null
957	>	*/
958	>	public V put(K key, V value) {
959	>	return putVal(key, value, false);
960	>	}
961
962	<	V get(Object key, int hash) {
963	<	if (count != 0) { // read-volatile
964	<	HashEntry<K,V> e = getFirst(hash);
965	<	while (e != null) {
966	<	if (e.hash == hash && key.equals(e.key)) {
967	<	V v = e.value;
968	<	if (v != null)
969	<	return v;
970	<	return readValueUnderLock(e); // recheck
962	>	/** Implementation for put and putIfAbsent */
963	>	final V putVal(K key, V value, boolean onlyIfAbsent) {
964	>	if (key == null || value == null) throw new NullPointerException();
965	>	int hash = spread(key.hashCode());
966	>	int binCount = 0;
967	>	for (Node<K,V>[] tab = table;;) {
968	>	Node<K,V> f; int n, i, fh;
969	>	if (tab == null || (n = tab.length) == 0)
970	>	tab = initTable();
971	>	else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
972	>	if (casTabAt(tab, i, null,
973	>	new Node<K,V>(hash, key, value, null)))
974	>	break;                   // no lock when adding to empty bin
975	>	}
976	>	else if ((fh = f.hash) == MOVED)
977	>	tab = helpTransfer(tab, f);
978	>	else {
979	>	V oldVal = null;
980	>	synchronized (f) {
981	>	if (tabAt(tab, i) == f) {
982	>	if (fh >= 0) {
983	>	binCount = 1;
984	>	for (Node<K,V> e = f;; ++binCount) {
985	>	K ek;
986	>	if (e.hash == hash &&
987	>	((ek = e.key) == key ||
988	>	(ek != null && key.equals(ek)))) {
989	>	oldVal = e.val;
990	>	if (!onlyIfAbsent)
991	>	e.val = value;
992	>	break;
993	>	}
994	>	Node<K,V> pred = e;
995	>	if ((e = e.next) == null) {
996	>	pred.next = new Node<K,V>(hash, key,
997	>	value, null);
998	>	break;
999	>	}
1000	>	}
1001	>	}
1002	>	else if (f instanceof TreeBin) {
1003	>	Node<K,V> p;
1004	>	binCount = 2;
1005	>	if ((p = ((TreeBin<K,V>)f).putTreeVal(hash, key,
1006	>	value)) != null) {
1007	>	oldVal = p.val;
1008	>	if (!onlyIfAbsent)
1009	>	p.val = value;
1010	>	}
1011	>	}
1012		}
1013	<	e = e.next;
1013	>	}
1014	>	if (binCount != 0) {
1015	>	if (binCount >= TREEIFY_THRESHOLD)
1016	>	treeifyBin(tab, i);
1017	>	if (oldVal != null)
1018	>	return oldVal;
1019	>	break;
1020		}
1021		}
335	–	return null;
1022		}
1023	+	addCount(1L, binCount);
1024	+	return null;
1025	+	}
1026
1027	<	boolean containsKey(Object key, int hash) {
1028	<	if (count != 0) { // read-volatile
1029	<	HashEntry<K,V> e = getFirst(hash);
1030	<	while (e != null) {
1031	<	if (e.hash == hash && key.equals(e.key))
1032	<	return true;
1033	<	e = e.next;
1027	>	/**
1028	>	* Copies all of the mappings from the specified map to this one.
1029	>	* These mappings replace any mappings that this map had for any of the
1030	>	* keys currently in the specified map.
1031	>	*
1032	>	* @param m mappings to be stored in this map
1033	>	*/
1034	>	public void putAll(Map<? extends K, ? extends V> m) {
1035	>	tryPresize(m.size());
1036	>	for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
1037	>	putVal(e.getKey(), e.getValue(), false);
1038	>	}
1039	>
1040	>	/**
1041	>	* Removes the key (and its corresponding value) from this map.
1042	>	* This method does nothing if the key is not in the map.
1043	>	*
1044	>	* @param  key the key that needs to be removed
1045	>	* @return the previous value associated with {@code key}, or
1046	>	*         {@code null} if there was no mapping for {@code key}
1047	>	* @throws NullPointerException if the specified key is null
1048	>	*/
1049	>	public V remove(Object key) {
1050	>	return replaceNode(key, null, null);
1051	>	}
1052	>
1053	>	/**
1054	>	* Implementation for the four public remove/replace methods:
1055	>	* Replaces node value with v, conditional upon match of cv if
1056	>	* non-null.  If resulting value is null, delete.
1057	>	*/
1058	>	final V replaceNode(Object key, V value, Object cv) {
1059	>	int hash = spread(key.hashCode());
1060	>	for (Node<K,V>[] tab = table;;) {
1061	>	Node<K,V> f; int n, i, fh;
1062	>	if (tab == null || (n = tab.length) == 0 ||
1063	>	(f = tabAt(tab, i = (n - 1) & hash)) == null)
1064	>	break;
1065	>	else if ((fh = f.hash) == MOVED)
1066	>	tab = helpTransfer(tab, f);
1067	>	else {
1068	>	V oldVal = null;
1069	>	boolean validated = false;
1070	>	synchronized (f) {
1071	>	if (tabAt(tab, i) == f) {
1072	>	if (fh >= 0) {
1073	>	validated = true;
1074	>	for (Node<K,V> e = f, pred = null;;) {
1075	>	K ek;
1076	>	if (e.hash == hash &&
1077	>	((ek = e.key) == key ||
1078	>	(ek != null && key.equals(ek)))) {
1079	>	V ev = e.val;
1080	>	if (cv == null || cv == ev ||
1081	>	(ev != null && cv.equals(ev))) {
1082	>	oldVal = ev;
1083	>	if (value != null)
1084	>	e.val = value;
1085	>	else if (pred != null)
1086	>	pred.next = e.next;
1087	>	else
1088	>	setTabAt(tab, i, e.next);
1089	>	}
1090	>	break;
1091	>	}
1092	>	pred = e;
1093	>	if ((e = e.next) == null)
1094	>	break;
1095	>	}
1096	>	}
1097	>	else if (f instanceof TreeBin) {
1098	>	validated = true;
1099	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1100	>	TreeNode<K,V> r, p;
1101	>	if ((r = t.root) != null &&
1102	>	(p = r.findTreeNode(hash, key, null)) != null) {
1103	>	V pv = p.val;
1104	>	if (cv == null || cv == pv ||
1105	>	(pv != null && cv.equals(pv))) {
1106	>	oldVal = pv;
1107	>	if (value != null)
1108	>	p.val = value;
1109	>	else if (t.removeTreeNode(p))
1110	>	setTabAt(tab, i, untreeify(t.first));
1111	>	}
1112	>	}
1113	>	}
1114	>	}
1115	>	}
1116	>	if (validated) {
1117	>	if (oldVal != null) {
1118	>	if (value == null)
1119	>	addCount(-1L, -1);
1120	>	return oldVal;
1121	>	}
1122	>	break;
1123		}
1124		}
347	–	return false;
1125		}
1126	+	return null;
1127	+	}
1128
1129	<	boolean containsValue(Object value) {
1130	<	if (count != 0) { // read-volatile
1131	<	HashEntry[] tab = table;
1132	<	int len = tab.length;
1133	<	for (int i = 0 ; i < len; i++) {
1134	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i];
1135	<	e != null ;
1136	<	e = e.next) {
1137	<	V v = e.value;
1138	<	if (v == null) // recheck
1139	<	v = readValueUnderLock(e);
1140	<	if (value.equals(v))
1141	<	return true;
1129	>	/**
1130	>	* Removes all of the mappings from this map.
1131	>	*/
1132	>	public void clear() {
1133	>	long delta = 0L; // negative number of deletions
1134	>	int i = 0;
1135	>	Node<K,V>[] tab = table;
1136	>	while (tab != null && i < tab.length) {
1137	>	int fh;
1138	>	Node<K,V> f = tabAt(tab, i);
1139	>	if (f == null)
1140	>	++i;
1141	>	else if ((fh = f.hash) == MOVED) {
1142	>	tab = helpTransfer(tab, f);
1143	>	i = 0; // restart
1144	>	}
1145	>	else {
1146	>	synchronized (f) {
1147	>	if (tabAt(tab, i) == f) {
1148	>	Node<K,V> p = (fh >= 0 ? f :
1149	>	(f instanceof TreeBin) ?
1150	>	((TreeBin<K,V>)f).first : null);
1151	>	while (p != null) {
1152	>	--delta;
1153	>	p = p.next;
1154	>	}
1155	>	setTabAt(tab, i++, null);
1156		}
1157		}
1158		}
366	–	return false;
1159		}
1160	+	if (delta != 0L)
1161	+	addCount(delta, -1);
1162	+	}
1163
1164	<	boolean replace(K key, int hash, V oldValue, V newValue) {
1165	<	lock();
1166	<	try {
1167	<	HashEntry<K,V> e = getFirst(hash);
1168	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1169	<	e = e.next;
1170	<
1171	<	boolean replaced = false;
1172	<	if (e != null && oldValue.equals(e.value)) {
1173	<	replaced = true;
1174	<	e.value = newValue;
1175	<	}
1176	<	return replaced;
1177	<	} finally {
1178	<	unlock();
1164	>	/**
1165	>	* Returns a {@link Set} view of the keys contained in this map.
1166	>	* The set is backed by the map, so changes to the map are
1167	>	* reflected in the set, and vice-versa. The set supports element
1168	>	* removal, which removes the corresponding mapping from this map,
1169	>	* via the {@code Iterator.remove}, {@code Set.remove},
1170	>	* {@code removeAll}, {@code retainAll}, and {@code clear}
1171	>	* operations.  It does not support the {@code add} or
1172	>	* {@code addAll} operations.
1173	>	*
1174	>	* <p>The view's {@code iterator} is a "weakly consistent" iterator
1175	>	* that will never throw {@link ConcurrentModificationException},
1176	>	* and guarantees to traverse elements as they existed upon
1177	>	* construction of the iterator, and may (but is not guaranteed to)
1178	>	* reflect any modifications subsequent to construction.
1179	>	*
1180	>	* @return the set view
1181	>	*/
1182	>	public KeySetView<K,V> keySet() {
1183	>	KeySetView<K,V> ks;
1184	>	return (ks = keySet) != null ? ks : (keySet = new KeySetView<K,V>(this, null));
1185	>	}
1186	>
1187	>	/**
1188	>	* Returns a {@link Collection} view of the values contained in this map.
1189	>	* The collection is backed by the map, so changes to the map are
1190	>	* reflected in the collection, and vice-versa.  The collection
1191	>	* supports element removal, which removes the corresponding
1192	>	* mapping from this map, via the {@code Iterator.remove},
1193	>	* {@code Collection.remove}, {@code removeAll},
1194	>	* {@code retainAll}, and {@code clear} operations.  It does not
1195	>	* support the {@code add} or {@code addAll} operations.
1196	>	*
1197	>	* <p>The view's {@code iterator} is a "weakly consistent" iterator
1198	>	* that will never throw {@link ConcurrentModificationException},
1199	>	* and guarantees to traverse elements as they existed upon
1200	>	* construction of the iterator, and may (but is not guaranteed to)
1201	>	* reflect any modifications subsequent to construction.
1202	>	*
1203	>	* @return the collection view
1204	>	*/
1205	>	public Collection<V> values() {
1206	>	ValuesView<K,V> vs;
1207	>	return (vs = values) != null ? vs : (values = new ValuesView<K,V>(this));
1208	>	}
1209	>
1210	>	/**
1211	>	* Returns a {@link Set} view of the mappings contained in this map.
1212	>	* The set is backed by the map, so changes to the map are
1213	>	* reflected in the set, and vice-versa.  The set supports element
1214	>	* removal, which removes the corresponding mapping from the map,
1215	>	* via the {@code Iterator.remove}, {@code Set.remove},
1216	>	* {@code removeAll}, {@code retainAll}, and {@code clear}
1217	>	* operations.
1218	>	*
1219	>	* <p>The view's {@code iterator} is a "weakly consistent" iterator
1220	>	* that will never throw {@link ConcurrentModificationException},
1221	>	* and guarantees to traverse elements as they existed upon
1222	>	* construction of the iterator, and may (but is not guaranteed to)
1223	>	* reflect any modifications subsequent to construction.
1224	>	*
1225	>	* @return the set view
1226	>	*/
1227	>	public Set<Map.Entry<K,V>> entrySet() {
1228	>	EntrySetView<K,V> es;
1229	>	return (es = entrySet) != null ? es : (entrySet = new EntrySetView<K,V>(this));
1230	>	}
1231	>
1232	>	/**
1233	>	* Returns the hash code value for this {@link Map}, i.e.,
1234	>	* the sum of, for each key-value pair in the map,
1235	>	* {@code key.hashCode() ^ value.hashCode()}.
1236	>	*
1237	>	* @return the hash code value for this map
1238	>	*/
1239	>	public int hashCode() {
1240	>	int h = 0;
1241	>	Node<K,V>[] t;
1242	>	if ((t = table) != null) {
1243	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1244	>	for (Node<K,V> p; (p = it.advance()) != null; )
1245	>	h += p.key.hashCode() ^ p.val.hashCode();
1246	>	}
1247	>	return h;
1248	>	}
1249	>
1250	>	/**
1251	>	* Returns a string representation of this map.  The string
1252	>	* representation consists of a list of key-value mappings (in no
1253	>	* particular order) enclosed in braces ("{@code {}}").  Adjacent
1254	>	* mappings are separated by the characters {@code ", "} (comma
1255	>	* and space).  Each key-value mapping is rendered as the key
1256	>	* followed by an equals sign ("{@code =}") followed by the
1257	>	* associated value.
1258	>	*
1259	>	* @return a string representation of this map
1260	>	*/
1261	>	public String toString() {
1262	>	Node<K,V>[] t;
1263	>	int f = (t = table) == null ? 0 : t.length;
1264	>	Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1265	>	StringBuilder sb = new StringBuilder();
1266	>	sb.append('{');
1267	>	Node<K,V> p;
1268	>	if ((p = it.advance()) != null) {
1269	>	for (;;) {
1270	>	K k = p.key;
1271	>	V v = p.val;
1272	>	sb.append(k == this ? "(this Map)" : k);
1273	>	sb.append('=');
1274	>	sb.append(v == this ? "(this Map)" : v);
1275	>	if ((p = it.advance()) == null)
1276	>	break;
1277	>	sb.append(',').append(' ');
1278		}
1279		}
1280	+	return sb.append('}').toString();
1281	+	}
1282
1283	<	V replace(K key, int hash, V newValue) {
1284	<	lock();
1285	<	try {
1286	<	HashEntry<K,V> e = getFirst(hash);
1287	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1288	<	e = e.next;
1289	<
1290	<	V oldValue = null;
1291	<	if (e != null) {
1292	<	oldValue = e.value;
1293	<	e.value = newValue;
1294	<	}
1295	<	return oldValue;
1296	<	} finally {
1297	<	unlock();
1283	>	/**
1284	>	* Compares the specified object with this map for equality.
1285	>	* Returns {@code true} if the given object is a map with the same
1286	>	* mappings as this map.  This operation may return misleading
1287	>	* results if either map is concurrently modified during execution
1288	>	* of this method.
1289	>	*
1290	>	* @param o object to be compared for equality with this map
1291	>	* @return {@code true} if the specified object is equal to this map
1292	>	*/
1293	>	public boolean equals(Object o) {
1294	>	if (o != this) {
1295	>	if (!(o instanceof Map))
1296	>	return false;
1297	>	Map<?,?> m = (Map<?,?>) o;
1298	>	Node<K,V>[] t;
1299	>	int f = (t = table) == null ? 0 : t.length;
1300	>	Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1301	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1302	>	V val = p.val;
1303	>	Object v = m.get(p.key);
1304	>	if (v == null || (v != val && !v.equals(val)))
1305	>	return false;
1306	>	}
1307	>	for (Map.Entry<?,?> e : m.entrySet()) {
1308	>	Object mk, mv, v;
1309	>	if ((mk = e.getKey()) == null ||
1310	>	(mv = e.getValue()) == null ||
1311	>	(v = get(mk)) == null ||
1312	>	(mv != v && !mv.equals(v)))
1313	>	return false;
1314		}
1315		}
1316	+	return true;
1317	+	}
1318
1319	+	/**
1320	+	* Stripped-down version of helper class used in previous version,
1321	+	* declared for the sake of serialization compatibility
1322	+	*/
1323	+	static class Segment<K,V> extends ReentrantLock implements Serializable {
1324	+	private static final long serialVersionUID = 2249069246763182397L;
1325	+	final float loadFactor;
1326	+	Segment(float lf) { this.loadFactor = lf; }
1327	+	}
1328
1329	<	V put(K key, int hash, V value, boolean onlyIfAbsent) {
1330	<	lock();
1331	<	try {
1332	<	int c = count;
1333	<	if (c++ > threshold) // ensure capacity
1334	<	rehash();
1335	<	HashEntry[] tab = table;
1336	<	int index = hash & (tab.length - 1);
1337	<	HashEntry<K,V> first = (HashEntry<K,V>) tab[index];
1338	<	HashEntry<K,V> e = first;
1339	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1340	<	e = e.next;
1341	<
1342	<	V oldValue;
1343	<	if (e != null) {
1344	<	oldValue = e.value;
1345	<	if (!onlyIfAbsent)
1346	<	e.value = value;
1347	<	}
1329	>	/**
1330	>	* Saves the state of the {@code ConcurrentHashMap} instance to a
1331	>	* stream (i.e., serializes it).
1332	>	* @param s the stream
1333	>	* @throws java.io.IOException if an I/O error occurs
1334	>	* @serialData
1335	>	* the key (Object) and value (Object)
1336	>	* for each key-value mapping, followed by a null pair.
1337	>	* The key-value mappings are emitted in no particular order.
1338	>	*/
1339	>	private void writeObject(java.io.ObjectOutputStream s)
1340	>	throws java.io.IOException {
1341	>	// For serialization compatibility
1342	>	// Emulate segment calculation from previous version of this class
1343	>	int sshift = 0;
1344	>	int ssize = 1;
1345	>	while (ssize < DEFAULT_CONCURRENCY_LEVEL) {
1346	>	++sshift;
1347	>	ssize <<= 1;
1348	>	}
1349	>	int segmentShift = 32 - sshift;
1350	>	int segmentMask = ssize - 1;
1351	>	@SuppressWarnings("unchecked") Segment<K,V>[] segments = (Segment<K,V>[])
1352	>	new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
1353	>	for (int i = 0; i < segments.length; ++i)
1354	>	segments[i] = new Segment<K,V>(LOAD_FACTOR);
1355	>	s.putFields().put("segments", segments);
1356	>	s.putFields().put("segmentShift", segmentShift);
1357	>	s.putFields().put("segmentMask", segmentMask);
1358	>	s.writeFields();
1359	>
1360	>	Node<K,V>[] t;
1361	>	if ((t = table) != null) {
1362	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1363	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1364	>	s.writeObject(p.key);
1365	>	s.writeObject(p.val);
1366	>	}
1367	>	}
1368	>	s.writeObject(null);
1369	>	s.writeObject(null);
1370	>	segments = null; // throw away
1371	>	}
1372	>
1373	>	/**
1374	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1375	>	* @param s the stream
1376	>	* @throws ClassNotFoundException if the class of a serialized object
1377	>	*         could not be found
1378	>	* @throws java.io.IOException if an I/O error occurs
1379	>	*/
1380	>	private void readObject(java.io.ObjectInputStream s)
1381	>	throws java.io.IOException, ClassNotFoundException {
1382	>	/*
1383	>	* To improve performance in typical cases, we create nodes
1384	>	* while reading, then place in table once size is known.
1385	>	* However, we must also validate uniqueness and deal with
1386	>	* overpopulated bins while doing so, which requires
1387	>	* specialized versions of putVal mechanics.
1388	>	*/
1389	>	sizeCtl = -1; // force exclusion for table construction
1390	>	s.defaultReadObject();
1391	>	long size = 0L;
1392	>	Node<K,V> p = null;
1393	>	for (;;) {
1394	>	@SuppressWarnings("unchecked") K k = (K) s.readObject();
1395	>	@SuppressWarnings("unchecked") V v = (V) s.readObject();
1396	>	if (k != null && v != null) {
1397	>	p = new Node<K,V>(spread(k.hashCode()), k, v, p);
1398	>	++size;
1399	>	}
1400	>	else
1401	>	break;
1402	>	}
1403	>	if (size == 0L)
1404	>	sizeCtl = 0;
1405	>	else {
1406	>	int n;
1407	>	if (size >= (long)(MAXIMUM_CAPACITY >>> 1))
1408	>	n = MAXIMUM_CAPACITY;
1409	>	else {
1410	>	int sz = (int)size;
1411	>	n = tableSizeFor(sz + (sz >>> 1) + 1);
1412	>	}
1413	>	@SuppressWarnings({"rawtypes","unchecked"})
1414	>	Node<K,V>[] tab = (Node<K,V>[])new Node[n];
1415	>	int mask = n - 1;
1416	>	long added = 0L;
1417	>	while (p != null) {
1418	>	boolean insertAtFront;
1419	>	Node<K,V> next = p.next, first;
1420	>	int h = p.hash, j = h & mask;
1421	>	if ((first = tabAt(tab, j)) == null)
1422	>	insertAtFront = true;
1423		else {
1424	<	oldValue = null;
1425	<	++modCount;
1426	<	tab[index] = new HashEntry<K,V>(key, hash, first, value);
1427	<	count = c; // write-volatile
1424	>	K k = p.key;
1425	>	if (first.hash < 0) {
1426	>	TreeBin<K,V> t = (TreeBin<K,V>)first;
1427	>	if (t.putTreeVal(h, k, p.val) == null)
1428	>	++added;
1429	>	insertAtFront = false;
1430	>	}
1431	>	else {
1432	>	int binCount = 0;
1433	>	insertAtFront = true;
1434	>	Node<K,V> q; K qk;
1435	>	for (q = first; q != null; q = q.next) {
1436	>	if (q.hash == h &&
1437	>	((qk = q.key) == k ||
1438	>	(qk != null && k.equals(qk)))) {
1439	>	insertAtFront = false;
1440	>	break;
1441	>	}
1442	>	++binCount;
1443	>	}
1444	>	if (insertAtFront && binCount >= TREEIFY_THRESHOLD) {
1445	>	insertAtFront = false;
1446	>	++added;
1447	>	p.next = first;
1448	>	TreeNode<K,V> hd = null, tl = null;
1449	>	for (q = p; q != null; q = q.next) {
1450	>	TreeNode<K,V> t = new TreeNode<K,V>
1451	>	(q.hash, q.key, q.val, null, null);
1452	>	if ((t.prev = tl) == null)
1453	>	hd = t;
1454	>	else
1455	>	tl.next = t;
1456	>	tl = t;
1457	>	}
1458	>	setTabAt(tab, j, new TreeBin<K,V>(hd));
1459	>	}
1460	>	}
1461		}
1462	<	return oldValue;
1463	<	} finally {
1464	<	unlock();
1462	>	if (insertAtFront) {
1463	>	++added;
1464	>	p.next = first;
1465	>	setTabAt(tab, j, p);
1466	>	}
1467	>	p = next;
1468		}
1469	+	table = tab;
1470	+	sizeCtl = n - (n >>> 2);
1471	+	baseCount = added;
1472		}
1473	+	}
1474
1475	<	void rehash() {
438	<	HashEntry[] oldTable = table;
439	<	int oldCapacity = oldTable.length;
440	<	if (oldCapacity >= MAXIMUM_CAPACITY)
441	<	return;
1475	>	// ConcurrentMap methods
1476
1477	<	/*
1478	<	* Reclassify nodes in each list to new Map.  Because we are
1479	<	* using power-of-two expansion, the elements from each bin
1480	<	* must either stay at same index, or move with a power of two
1481	<	* offset. We eliminate unnecessary node creation by catching
1482	<	* cases where old nodes can be reused because their next
1483	<	* fields won't change. Statistically, at the default
1484	<	* threshold, only about one-sixth of them need cloning when
1485	<	* a table doubles. The nodes they replace will be garbage
1486	<	* 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;
1477	>	/**
1478	>	* {@inheritDoc}
1479	>	*
1480	>	* @return the previous value associated with the specified key,
1481	>	*         or {@code null} if there was no mapping for the key
1482	>	* @throws NullPointerException if the specified key or value is null
1483	>	*/
1484	>	public V putIfAbsent(K key, V value) {
1485	>	return putVal(key, value, true);
1486	>	}
1487
1488	<	else {
1489	<	// Reuse trailing consecutive sequence at same slot
1490	<	HashEntry<K,V> lastRun = e;
1491	<	int lastIdx = idx;
1492	<	for (HashEntry<K,V> last = next;
1493	<	last != null;
1494	<	last = last.next) {
1495	<	int k = last.hash & sizeMask;
1496	<	if (k != lastIdx) {
1497	<	lastIdx = k;
1498	<	lastRun = last;
1488	>	/**
1489	>	* {@inheritDoc}
1490	>	*
1491	>	* @throws NullPointerException if the specified key is null
1492	>	*/
1493	>	public boolean remove(Object key, Object value) {
1494	>	if (key == null)
1495	>	throw new NullPointerException();
1496	>	return value != null && replaceNode(key, null, value) != null;
1497	>	}
1498	>
1499	>	/**
1500	>	* {@inheritDoc}
1501	>	*
1502	>	* @throws NullPointerException if any of the arguments are null
1503	>	*/
1504	>	public boolean replace(K key, V oldValue, V newValue) {
1505	>	if (key == null || oldValue == null || newValue == null)
1506	>	throw new NullPointerException();
1507	>	return replaceNode(key, newValue, oldValue) != null;
1508	>	}
1509	>
1510	>	/**
1511	>	* {@inheritDoc}
1512	>	*
1513	>	* @return the previous value associated with the specified key,
1514	>	*         or {@code null} if there was no mapping for the key
1515	>	* @throws NullPointerException if the specified key or value is null
1516	>	*/
1517	>	public V replace(K key, V value) {
1518	>	if (key == null || value == null)
1519	>	throw new NullPointerException();
1520	>	return replaceNode(key, value, null);
1521	>	}
1522	>
1523	>	// Overrides of JDK8+ Map extension method defaults
1524	>
1525	>	/**
1526	>	* Returns the value to which the specified key is mapped, or the
1527	>	* given default value if this map contains no mapping for the
1528	>	* key.
1529	>	*
1530	>	* @param key the key whose associated value is to be returned
1531	>	* @param defaultValue the value to return if this map contains
1532	>	* no mapping for the given key
1533	>	* @return the mapping for the key, if present; else the default value
1534	>	* @throws NullPointerException if the specified key is null
1535	>	*/
1536	>	public V getOrDefault(Object key, V defaultValue) {
1537	>	V v;
1538	>	return (v = get(key)) == null ? defaultValue : v;
1539	>	}
1540	>
1541	>	public void forEach(BiConsumer<? super K, ? super V> action) {
1542	>	if (action == null) throw new NullPointerException();
1543	>	Node<K,V>[] t;
1544	>	if ((t = table) != null) {
1545	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1546	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1547	>	action.accept(p.key, p.val);
1548	>	}
1549	>	}
1550	>	}
1551	>
1552	>	public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1553	>	if (function == null) throw new NullPointerException();
1554	>	Node<K,V>[] t;
1555	>	if ((t = table) != null) {
1556	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1557	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1558	>	V oldValue = p.val;
1559	>	for (K key = p.key;;) {
1560	>	V newValue = function.apply(key, oldValue);
1561	>	if (newValue == null)
1562	>	throw new NullPointerException();
1563	>	if (replaceNode(key, newValue, oldValue) != null ||
1564	>	(oldValue = get(key)) == null)
1565	>	break;
1566	>	}
1567	>	}
1568	>	}
1569	>	}
1570	>
1571	>	/**
1572	>	* If the specified key is not already associated with a value,
1573	>	* attempts to compute its value using the given mapping function
1574	>	* and enters it into this map unless {@code null}.  The entire
1575	>	* method invocation is performed atomically, so the function is
1576	>	* applied at most once per key.  Some attempted update operations
1577	>	* on this map by other threads may be blocked while computation
1578	>	* is in progress, so the computation should be short and simple,
1579	>	* and must not attempt to update any other mappings of this map.
1580	>	*
1581	>	* @param key key with which the specified value is to be associated
1582	>	* @param mappingFunction the function to compute a value
1583	>	* @return the current (existing or computed) value associated with
1584	>	*         the specified key, or null if the computed value is null
1585	>	* @throws NullPointerException if the specified key or mappingFunction
1586	>	*         is null
1587	>	* @throws IllegalStateException if the computation detectably
1588	>	*         attempts a recursive update to this map that would
1589	>	*         otherwise never complete
1590	>	* @throws RuntimeException or Error if the mappingFunction does so,
1591	>	*         in which case the mapping is left unestablished
1592	>	*/
1593	>	public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
1594	>	if (key == null || mappingFunction == null)
1595	>	throw new NullPointerException();
1596	>	int h = spread(key.hashCode());
1597	>	V val = null;
1598	>	int binCount = 0;
1599	>	for (Node<K,V>[] tab = table;;) {
1600	>	Node<K,V> f; int n, i, fh;
1601	>	if (tab == null || (n = tab.length) == 0)
1602	>	tab = initTable();
1603	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1604	>	Node<K,V> r = new ReservationNode<K,V>();
1605	>	synchronized (r) {
1606	>	if (casTabAt(tab, i, null, r)) {
1607	>	binCount = 1;
1608	>	Node<K,V> node = null;
1609	>	try {
1610	>	if ((val = mappingFunction.apply(key)) != null)
1611	>	node = new Node<K,V>(h, key, val, null);
1612	>	} finally {
1613	>	setTabAt(tab, i, node);
1614	>	}
1615	>	}
1616	>	}
1617	>	if (binCount != 0)
1618	>	break;
1619	>	}
1620	>	else if ((fh = f.hash) == MOVED)
1621	>	tab = helpTransfer(tab, f);
1622	>	else {
1623	>	boolean added = false;
1624	>	synchronized (f) {
1625	>	if (tabAt(tab, i) == f) {
1626	>	if (fh >= 0) {
1627	>	binCount = 1;
1628	>	for (Node<K,V> e = f;; ++binCount) {
1629	>	K ek; V ev;
1630	>	if (e.hash == h &&
1631	>	((ek = e.key) == key ||
1632	>	(ek != null && key.equals(ek)))) {
1633	>	val = e.val;
1634	>	break;
1635	>	}
1636	>	Node<K,V> pred = e;
1637	>	if ((e = e.next) == null) {
1638	>	if ((val = mappingFunction.apply(key)) != null) {
1639	>	added = true;
1640	>	pred.next = new Node<K,V>(h, key, val, null);
1641	>	}
1642	>	break;
1643	>	}
1644	>	}
1645	>	}
1646	>	else if (f instanceof TreeBin) {
1647	>	binCount = 2;
1648	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1649	>	TreeNode<K,V> r, p;
1650	>	if ((r = t.root) != null &&
1651	>	(p = r.findTreeNode(h, key, null)) != null)
1652	>	val = p.val;
1653	>	else if ((val = mappingFunction.apply(key)) != null) {
1654	>	added = true;
1655	>	t.putTreeVal(h, key, val);
1656		}
1657		}
1658	<	newTable[lastIdx] = lastRun;
1658	>	}
1659	>	}
1660	>	if (binCount != 0) {
1661	>	if (binCount >= TREEIFY_THRESHOLD)
1662	>	treeifyBin(tab, i);
1663	>	if (!added)
1664	>	return val;
1665	>	break;
1666	>	}
1667	>	}
1668	>	}
1669	>	if (val != null)
1670	>	addCount(1L, binCount);
1671	>	return val;
1672	>	}
1673
1674	<	// Clone all remaining nodes
1675	<	for (HashEntry<K,V> p = e; p != lastRun; p = p.next) {
1676	<	int k = p.hash & sizeMask;
1677	<	HashEntry<K,V> n = (HashEntry<K,V>)newTable[k];
1678	<	newTable[k] = new HashEntry<K,V>(p.key, p.hash,
1679	<	n, p.value);
1674	>	/**
1675	>	* If the value for the specified key is present, attempts to
1676	>	* compute a new mapping given the key and its current mapped
1677	>	* value.  The entire method invocation is performed atomically.
1678	>	* Some attempted update operations on this map by other threads
1679	>	* may be blocked while computation is in progress, so the
1680	>	* computation should be short and simple, and must not attempt to
1681	>	* update any other mappings of this map.
1682	>	*
1683	>	* @param key key with which a value may be associated
1684	>	* @param remappingFunction the function to compute a value
1685	>	* @return the new value associated with the specified key, or null if none
1686	>	* @throws NullPointerException if the specified key or remappingFunction
1687	>	*         is null
1688	>	* @throws IllegalStateException if the computation detectably
1689	>	*         attempts a recursive update to this map that would
1690	>	*         otherwise never complete
1691	>	* @throws RuntimeException or Error if the remappingFunction does so,
1692	>	*         in which case the mapping is unchanged
1693	>	*/
1694	>	public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1695	>	if (key == null || remappingFunction == null)
1696	>	throw new NullPointerException();
1697	>	int h = spread(key.hashCode());
1698	>	V val = null;
1699	>	int delta = 0;
1700	>	int binCount = 0;
1701	>	for (Node<K,V>[] tab = table;;) {
1702	>	Node<K,V> f; int n, i, fh;
1703	>	if (tab == null || (n = tab.length) == 0)
1704	>	tab = initTable();
1705	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null)
1706	>	break;
1707	>	else if ((fh = f.hash) == MOVED)
1708	>	tab = helpTransfer(tab, f);
1709	>	else {
1710	>	synchronized (f) {
1711	>	if (tabAt(tab, i) == f) {
1712	>	if (fh >= 0) {
1713	>	binCount = 1;
1714	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1715	>	K ek;
1716	>	if (e.hash == h &&
1717	>	((ek = e.key) == key ||
1718	>	(ek != null && key.equals(ek)))) {
1719	>	val = remappingFunction.apply(key, e.val);
1720	>	if (val != null)
1721	>	e.val = val;
1722	>	else {
1723	>	delta = -1;
1724	>	Node<K,V> en = e.next;
1725	>	if (pred != null)
1726	>	pred.next = en;
1727	>	else
1728	>	setTabAt(tab, i, en);
1729	>	}
1730	>	break;
1731	>	}
1732	>	pred = e;
1733	>	if ((e = e.next) == null)
1734	>	break;
1735	>	}
1736	>	}
1737	>	else if (f instanceof TreeBin) {
1738	>	binCount = 2;
1739	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1740	>	TreeNode<K,V> r, p;
1741	>	if ((r = t.root) != null &&
1742	>	(p = r.findTreeNode(h, key, null)) != null) {
1743	>	val = remappingFunction.apply(key, p.val);
1744	>	if (val != null)
1745	>	p.val = val;
1746	>	else {
1747	>	delta = -1;
1748	>	if (t.removeTreeNode(p))
1749	>	setTabAt(tab, i, untreeify(t.first));
1750	>	}
1751	>	}
1752		}
1753		}
1754		}
1755	+	if (binCount != 0)
1756	+	break;
1757		}
498	–	table = newTable;
1758		}
1759	+	if (delta != 0)
1760	+	addCount((long)delta, binCount);
1761	+	return val;
1762	+	}
1763
1764	<	/**
1765	<	* Remove; match on key only if value null, else match both.
1766	<	*/
1767	<	V remove(Object key, int hash, Object value) {
1768	<	lock();
1769	<	try {
1770	<	int c = count - 1;
1771	<	HashEntry[] tab = table;
1772	<	int index = hash & (tab.length - 1);
1773	<	HashEntry<K,V> first = (HashEntry<K,V>)tab[index];
1774	<	HashEntry<K,V> e = first;
1775	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1776	<	e = e.next;
1777	<
1778	<	V oldValue = null;
1779	<	if (e != null) {
1780	<	V v = e.value;
1781	<	if (value == null || value.equals(v)) {
1782	<	oldValue = v;
1783	<	// All entries following removed node can stay
1784	<	// in list, but all preceding ones need to be
1785	<	// cloned.
1786	<	++modCount;
1787	<	HashEntry<K,V> newFirst = e.next;
1788	<	for (HashEntry<K,V> p = first; p != e; p = p.next)
1789	<	newFirst = new HashEntry<K,V>(p.key, p.hash,
1790	<	newFirst, p.value);
1791	<	tab[index] = newFirst;
1792	<	count = c; // write-volatile
1764	>	/**
1765	>	* Attempts to compute a mapping for the specified key and its
1766	>	* current mapped value (or {@code null} if there is no current
1767	>	* mapping). The entire method invocation is performed atomically.
1768	>	* Some attempted update operations on this map by other threads
1769	>	* may be blocked while computation is in progress, so the
1770	>	* computation should be short and simple, and must not attempt to
1771	>	* update any other mappings of this Map.
1772	>	*
1773	>	* @param key key with which the specified value is to be associated
1774	>	* @param remappingFunction the function to compute a value
1775	>	* @return the new value associated with the specified key, or null if none
1776	>	* @throws NullPointerException if the specified key or remappingFunction
1777	>	*         is null
1778	>	* @throws IllegalStateException if the computation detectably
1779	>	*         attempts a recursive update to this map that would
1780	>	*         otherwise never complete
1781	>	* @throws RuntimeException or Error if the remappingFunction does so,
1782	>	*         in which case the mapping is unchanged
1783	>	*/
1784	>	public V compute(K key,
1785	>	BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1786	>	if (key == null || remappingFunction == null)
1787	>	throw new NullPointerException();
1788	>	int h = spread(key.hashCode());
1789	>	V val = null;
1790	>	int delta = 0;
1791	>	int binCount = 0;
1792	>	for (Node<K,V>[] tab = table;;) {
1793	>	Node<K,V> f; int n, i, fh;
1794	>	if (tab == null || (n = tab.length) == 0)
1795	>	tab = initTable();
1796	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1797	>	Node<K,V> r = new ReservationNode<K,V>();
1798	>	synchronized (r) {
1799	>	if (casTabAt(tab, i, null, r)) {
1800	>	binCount = 1;
1801	>	Node<K,V> node = null;
1802	>	try {
1803	>	if ((val = remappingFunction.apply(key, null)) != null) {
1804	>	delta = 1;
1805	>	node = new Node<K,V>(h, key, val, null);
1806	>	}
1807	>	} finally {
1808	>	setTabAt(tab, i, node);
1809	>	}
1810		}
1811		}
1812	<	return oldValue;
1813	<	} finally {
1814	<	unlock();
1812	>	if (binCount != 0)
1813	>	break;
1814	>	}
1815	>	else if ((fh = f.hash) == MOVED)
1816	>	tab = helpTransfer(tab, f);
1817	>	else {
1818	>	synchronized (f) {
1819	>	if (tabAt(tab, i) == f) {
1820	>	if (fh >= 0) {
1821	>	binCount = 1;
1822	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1823	>	K ek;
1824	>	if (e.hash == h &&
1825	>	((ek = e.key) == key ||
1826	>	(ek != null && key.equals(ek)))) {
1827	>	val = remappingFunction.apply(key, e.val);
1828	>	if (val != null)
1829	>	e.val = val;
1830	>	else {
1831	>	delta = -1;
1832	>	Node<K,V> en = e.next;
1833	>	if (pred != null)
1834	>	pred.next = en;
1835	>	else
1836	>	setTabAt(tab, i, en);
1837	>	}
1838	>	break;
1839	>	}
1840	>	pred = e;
1841	>	if ((e = e.next) == null) {
1842	>	val = remappingFunction.apply(key, null);
1843	>	if (val != null) {
1844	>	delta = 1;
1845	>	pred.next =
1846	>	new Node<K,V>(h, key, val, null);
1847	>	}
1848	>	break;
1849	>	}
1850	>	}
1851	>	}
1852	>	else if (f instanceof TreeBin) {
1853	>	binCount = 1;
1854	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1855	>	TreeNode<K,V> r, p;
1856	>	if ((r = t.root) != null)
1857	>	p = r.findTreeNode(h, key, null);
1858	>	else
1859	>	p = null;
1860	>	V pv = (p == null) ? null : p.val;
1861	>	val = remappingFunction.apply(key, pv);
1862	>	if (val != null) {
1863	>	if (p != null)
1864	>	p.val = val;
1865	>	else {
1866	>	delta = 1;
1867	>	t.putTreeVal(h, key, val);
1868	>	}
1869	>	}
1870	>	else if (p != null) {
1871	>	delta = -1;
1872	>	if (t.removeTreeNode(p))
1873	>	setTabAt(tab, i, untreeify(t.first));
1874	>	}
1875	>	}
1876	>	}
1877	>	}
1878	>	if (binCount != 0) {
1879	>	if (binCount >= TREEIFY_THRESHOLD)
1880	>	treeifyBin(tab, i);
1881	>	break;
1882	>	}
1883		}
1884		}
1885	+	if (delta != 0)
1886	+	addCount((long)delta, binCount);
1887	+	return val;
1888	+	}
1889
1890	<	void clear() {
1891	<	if (count != 0) {
1892	<	lock();
1893	<	try {
1894	<	HashEntry[] tab = table;
1895	<	for (int i = 0; i < tab.length ; i++)
1896	<	tab[i] = null;
1897	<	++modCount;
1898	<	count = 0; // write-volatile
1899	<	} finally {
1900	<	unlock();
1890	>	/**
1891	>	* If the specified key is not already associated with a
1892	>	* (non-null) value, associates it with the given value.
1893	>	* Otherwise, replaces the value with the results of the given
1894	>	* remapping function, or removes if {@code null}. The entire
1895	>	* method invocation is performed atomically.  Some attempted
1896	>	* update operations on this map by other threads may be blocked
1897	>	* while computation is in progress, so the computation should be
1898	>	* short and simple, and must not attempt to update any other
1899	>	* mappings of this Map.
1900	>	*
1901	>	* @param key key with which the specified value is to be associated
1902	>	* @param value the value to use if absent
1903	>	* @param remappingFunction the function to recompute a value if present
1904	>	* @return the new value associated with the specified key, or null if none
1905	>	* @throws NullPointerException if the specified key or the
1906	>	*         remappingFunction is null
1907	>	* @throws RuntimeException or Error if the remappingFunction does so,
1908	>	*         in which case the mapping is unchanged
1909	>	*/
1910	>	public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1911	>	if (key == null || value == null || remappingFunction == null)
1912	>	throw new NullPointerException();
1913	>	int h = spread(key.hashCode());
1914	>	V val = null;
1915	>	int delta = 0;
1916	>	int binCount = 0;
1917	>	for (Node<K,V>[] tab = table;;) {
1918	>	Node<K,V> f; int n, i, fh;
1919	>	if (tab == null || (n = tab.length) == 0)
1920	>	tab = initTable();
1921	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1922	>	if (casTabAt(tab, i, null, new Node<K,V>(h, key, value, null))) {
1923	>	delta = 1;
1924	>	val = value;
1925	>	break;
1926	>	}
1927	>	}
1928	>	else if ((fh = f.hash) == MOVED)
1929	>	tab = helpTransfer(tab, f);
1930	>	else {
1931	>	synchronized (f) {
1932	>	if (tabAt(tab, i) == f) {
1933	>	if (fh >= 0) {
1934	>	binCount = 1;
1935	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1936	>	K ek;
1937	>	if (e.hash == h &&
1938	>	((ek = e.key) == key ||
1939	>	(ek != null && key.equals(ek)))) {
1940	>	val = remappingFunction.apply(e.val, value);
1941	>	if (val != null)
1942	>	e.val = val;
1943	>	else {
1944	>	delta = -1;
1945	>	Node<K,V> en = e.next;
1946	>	if (pred != null)
1947	>	pred.next = en;
1948	>	else
1949	>	setTabAt(tab, i, en);
1950	>	}
1951	>	break;
1952	>	}
1953	>	pred = e;
1954	>	if ((e = e.next) == null) {
1955	>	delta = 1;
1956	>	val = value;
1957	>	pred.next =
1958	>	new Node<K,V>(h, key, val, null);
1959	>	break;
1960	>	}
1961	>	}
1962	>	}
1963	>	else if (f instanceof TreeBin) {
1964	>	binCount = 2;
1965	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1966	>	TreeNode<K,V> r = t.root;
1967	>	TreeNode<K,V> p = (r == null) ? null :
1968	>	r.findTreeNode(h, key, null);
1969	>	val = (p == null) ? value :
1970	>	remappingFunction.apply(p.val, value);
1971	>	if (val != null) {
1972	>	if (p != null)
1973	>	p.val = val;
1974	>	else {
1975	>	delta = 1;
1976	>	t.putTreeVal(h, key, val);
1977	>	}
1978	>	}
1979	>	else if (p != null) {
1980	>	delta = -1;
1981	>	if (t.removeTreeNode(p))
1982	>	setTabAt(tab, i, untreeify(t.first));
1983	>	}
1984	>	}
1985	>	}
1986	>	}
1987	>	if (binCount != 0) {
1988	>	if (binCount >= TREEIFY_THRESHOLD)
1989	>	treeifyBin(tab, i);
1990	>	break;
1991		}
1992		}
1993		}
1994	+	if (delta != 0)
1995	+	addCount((long)delta, binCount);
1996	+	return val;
1997		}
1998
1999	+	// Hashtable legacy methods
2000
2001	+	/**
2002	+	* Legacy method testing if some key maps into the specified value
2003	+	* in this table.  This method is identical in functionality to
2004	+	* {@link #containsValue(Object)}, and exists solely to ensure
2005	+	* full compatibility with class {@link java.util.Hashtable},
2006	+	* which supported this method prior to introduction of the
2007	+	* Java Collections framework.
2008	+	*
2009	+	* @param  value a value to search for
2010	+	* @return {@code true} if and only if some key maps to the
2011	+	*         {@code value} argument in this table as
2012	+	*         determined by the {@code equals} method;
2013	+	*         {@code false} otherwise
2014	+	* @throws NullPointerException if the specified value is null
2015	+	*/
2016	+	@Deprecated public boolean contains(Object value) {
2017	+	return containsValue(value);
2018	+	}
2019
2020	<	/* ---------------- Public operations -------------- */
2020	>	/**
2021	>	* Returns an enumeration of the keys in this table.
2022	>	*
2023	>	* @return an enumeration of the keys in this table
2024	>	* @see #keySet()
2025	>	*/
2026	>	public Enumeration<K> keys() {
2027	>	Node<K,V>[] t;
2028	>	int f = (t = table) == null ? 0 : t.length;
2029	>	return new KeyIterator<K,V>(t, f, 0, f, this);
2030	>	}
2031
2032		/**
2033	<	* Creates a new, empty map with the specified initial
560	<	* capacity, load factor, and concurrency level.
2033	>	* Returns an enumeration of the values in this table.
2034		*
2035	<	* @param initialCapacity the initial capacity. The implementation
2036	<	* 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.
2035	>	* @return an enumeration of the values in this table
2036	>	* @see #values()
2037		*/
2038	<	public ConcurrentHashMap(int initialCapacity,
2039	<	float loadFactor, int concurrencyLevel) {
2040	<	if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
2041	<	throw new IllegalArgumentException();
2038	>	public Enumeration<V> elements() {
2039	>	Node<K,V>[] t;
2040	>	int f = (t = table) == null ? 0 : t.length;
2041	>	return new ValueIterator<K,V>(t, f, 0, f, this);
2042	>	}
2043
2044	<	if (concurrencyLevel > MAX_SEGMENTS)
580	<	concurrencyLevel = MAX_SEGMENTS;
2044	>	// ConcurrentHashMap-only methods
2045
2046	<	// Find power-of-two sizes best matching arguments
2047	<	int sshift = 0;
2048	<	int ssize = 1;
2049	<	while (ssize < concurrencyLevel) {
2050	<	++sshift;
2051	<	ssize <<= 1;
2052	<	}
2053	<	segmentShift = 32 - sshift;
2054	<	segmentMask = ssize - 1;
2055	<	this.segments = new Segment[ssize];
2056	<
2057	<	if (initialCapacity > MAXIMUM_CAPACITY)
2058	<	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);
2046	>	/**
2047	>	* Returns the number of mappings. This method should be used
2048	>	* instead of {@link #size} because a ConcurrentHashMap may
2049	>	* contain more mappings than can be represented as an int. The
2050	>	* value returned is an estimate; the actual count may differ if
2051	>	* there are concurrent insertions or removals.
2052	>	*
2053	>	* @return the number of mappings
2054	>	* @since 1.8
2055	>	*/
2056	>	public long mappingCount() {
2057	>	long n = sumCount();
2058	>	return (n < 0L) ? 0L : n; // ignore transient negative values
2059		}
2060
2061		/**
2062	<	* Creates a new, empty map with the specified initial
2063	<	* capacity,  and with default load factor (<tt>0.75f</tt>)
609	<	* and concurrencyLevel (<tt>16</tt>).
2062	>	* Creates a new {@link Set} backed by a ConcurrentHashMap
2063	>	* from the given type to {@code Boolean.TRUE}.
2064		*
2065	<	* @param initialCapacity the initial capacity. The implementation
2066	<	* performs internal sizing to accommodate this many elements.
2065	>	* @param <K> the element type of the returned set
2066	>	* @return the new set
2067	>	* @since 1.8
2068	>	*/
2069	>	public static <K> KeySetView<K,Boolean> newKeySet() {
2070	>	return new KeySetView<K,Boolean>
2071	>	(new ConcurrentHashMap<K,Boolean>(), Boolean.TRUE);
2072	>	}
2073	>
2074	>	/**
2075	>	* Creates a new {@link Set} backed by a ConcurrentHashMap
2076	>	* from the given type to {@code Boolean.TRUE}.
2077	>	*
2078	>	* @param initialCapacity The implementation performs internal
2079	>	* sizing to accommodate this many elements.
2080	>	* @param <K> the element type of the returned set
2081	>	* @return the new set
2082		* @throws IllegalArgumentException if the initial capacity of
2083	<	* elements is negative.
2083	>	* elements is negative
2084	>	* @since 1.8
2085		*/
2086	<	public ConcurrentHashMap(int initialCapacity) {
2087	<	this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2086	>	public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
2087	>	return new KeySetView<K,Boolean>
2088	>	(new ConcurrentHashMap<K,Boolean>(initialCapacity), Boolean.TRUE);
2089		}
2090
2091		/**
2092	<	* Creates a new, empty map with a default initial capacity
2093	<	* (<tt>16</tt>), load factor (<tt>0.75f</tt>) and
2094	<	* concurrencyLevel (<tt>16</tt>).
2092	>	* Returns a {@link Set} view of the keys in this map, using the
2093	>	* given common mapped value for any additions (i.e., {@link
2094	>	* Collection#add} and {@link Collection#addAll(Collection)}).
2095	>	* This is of course only appropriate if it is acceptable to use
2096	>	* the same value for all additions from this view.
2097	>	*
2098	>	* @param mappedValue the mapped value to use for any additions
2099	>	* @return the set view
2100	>	* @throws NullPointerException if the mappedValue is null
2101		*/
2102	<	public ConcurrentHashMap() {
2103	<	this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2102	>	public KeySetView<K,V> keySet(V mappedValue) {
2103	>	if (mappedValue == null)
2104	>	throw new NullPointerException();
2105	>	return new KeySetView<K,V>(this, mappedValue);
2106		}
2107
2108	+	/* ---------------- Special Nodes -------------- */
2109	+
2110		/**
2111	<	* 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
2111	>	* A node inserted at head of bins during transfer operations.
2112		*/
2113	<	public ConcurrentHashMap(Map<? extends K, ? extends V> t) {
2114	<	this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1,
2115	<	DEFAULT_INITIAL_CAPACITY),
2116	<	DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2117	<	putAll(t);
2113	>	static final class ForwardingNode<K,V> extends Node<K,V> {
2114	>	final Node<K,V>[] nextTable;
2115	>	ForwardingNode(Node<K,V>[] tab) {
2116	>	super(MOVED, null, null, null);
2117	>	this.nextTable = tab;
2118	>	}
2119	>
2120	>	Node<K,V> find(int h, Object k) {
2121	>	// loop to avoid arbitrarily deep recursion on forwarding nodes
2122	>	outer: for (Node<K,V>[] tab = nextTable;;) {
2123	>	Node<K,V> e; int n;
2124	>	if (k == null || tab == null || (n = tab.length) == 0 ||
2125	>	(e = tabAt(tab, (n - 1) & h)) == null)
2126	>	return null;
2127	>	for (;;) {
2128	>	int eh; K ek;
2129	>	if ((eh = e.hash) == h &&
2130	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
2131	>	return e;
2132	>	if (eh < 0) {
2133	>	if (e instanceof ForwardingNode) {
2134	>	tab = ((ForwardingNode<K,V>)e).nextTable;
2135	>	continue outer;
2136	>	}
2137	>	else
2138	>	return e.find(h, k);
2139	>	}
2140	>	if ((e = e.next) == null)
2141	>	return null;
2142	>	}
2143	>	}
2144	>	}
2145		}
2146
2147	<	// inherit Map javadoc
2148	<	public boolean isEmpty() {
2149	<	final Segment[] segments = this.segments;
2150	<	/*
2151	<	* We keep track of per-segment modCounts to avoid ABA
2152	<	* 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;
2147	>	/**
2148	>	* A place-holder node used in computeIfAbsent and compute
2149	>	*/
2150	>	static final class ReservationNode<K,V> extends Node<K,V> {
2151	>	ReservationNode() {
2152	>	super(RESERVED, null, null, null);
2153		}
2154	<	// If mcsum happens to be zero, then we know we got a snapshot
2155	<	// before any modifications at all were made.  This is
2156	<	// probably common enough to bother tracking.
2157	<	if (mcsum != 0) {
2158	<	for (int i = 0; i < segments.length; ++i) {
2159	<	if (segments[i].count != 0 ||
2160	<	mc[i] != segments[i].modCount)
2161	<	return false;
2154	>
2155	>	Node<K,V> find(int h, Object k) {
2156	>	return null;
2157	>	}
2158	>	}
2159	>
2160	>	/* ---------------- Table Initialization and Resizing -------------- */
2161	>
2162	>	/**
2163	>	* Initializes table, using the size recorded in sizeCtl.
2164	>	*/
2165	>	private final Node<K,V>[] initTable() {
2166	>	Node<K,V>[] tab; int sc;
2167	>	while ((tab = table) == null || tab.length == 0) {
2168	>	if ((sc = sizeCtl) < 0)
2169	>	Thread.yield(); // lost initialization race; just spin
2170	>	else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2171	>	try {
2172	>	if ((tab = table) == null || tab.length == 0) {
2173	>	int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
2174	>	@SuppressWarnings({"rawtypes","unchecked"})
2175	>	Node<K,V>[] nt = (Node<K,V>[])new Node[n];
2176	>	table = tab = nt;
2177	>	sc = n - (n >>> 2);
2178	>	}
2179	>	} finally {
2180	>	sizeCtl = sc;
2181	>	}
2182	>	break;
2183		}
2184		}
2185	<	return true;
2185	>	return tab;
2186		}
2187
2188	<	// inherit Map javadoc
2189	<	public int size() {
2190	<	final Segment[] segments = this.segments;
2191	<	long sum = 0;
2192	<	long check = 0;
2193	<	int[] mc = new int[segments.length];
2194	<	// Try a few times to get accurate count. On failure due to
2195	<	// continuous async changes in table, resort to locking.
2196	<	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
2197	<	check = 0;
2198	<	sum = 0;
2199	<	int mcsum = 0;
2200	<	for (int i = 0; i < segments.length; ++i) {
2201	<	sum += segments[i].count;
2202	<	mcsum += mc[i] = segments[i].modCount;
2203	<	}
2204	<	if (mcsum != 0) {
2205	<	for (int i = 0; i < segments.length; ++i) {
2206	<	check += segments[i].count;
2207	<	if (mc[i] != segments[i].modCount) {
2208	<	check = -1; // force retry
2188	>	/**
2189	>	* Adds to count, and if table is too small and not already
2190	>	* resizing, initiates transfer. If already resizing, helps
2191	>	* perform transfer if work is available.  Rechecks occupancy
2192	>	* after a transfer to see if another resize is already needed
2193	>	* because resizings are lagging additions.
2194	>	*
2195	>	* @param x the count to add
2196	>	* @param check if <0, don't check resize, if <= 1 only check if uncontended
2197	>	*/
2198	>	private final void addCount(long x, int check) {
2199	>	CounterCell[] as; long b, s;
2200	>	if ((as = counterCells) != null ||
2201	>	!U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
2202	>	CounterCell a; long v; int m;
2203	>	boolean uncontended = true;
2204	>	if (as == null || (m = as.length - 1) < 0 ||
2205	>	(a = as[ThreadLocalRandom.getProbe() & m]) == null ||
2206	>	!(uncontended =
2207	>	U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
2208	>	fullAddCount(x, uncontended);
2209	>	return;
2210	>	}
2211	>	if (check <= 1)
2212	>	return;
2213	>	s = sumCount();
2214	>	}
2215	>	if (check >= 0) {
2216	>	Node<K,V>[] tab, nt; int sc;
2217	>	while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
2218	>	tab.length < MAXIMUM_CAPACITY) {
2219	>	if (sc < 0) {
2220	>	if (sc == -1 || transferIndex <= transferOrigin ||
2221	>	(nt = nextTable) == null)
2222		break;
2223	+	if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2224	+	transfer(tab, nt);
2225	+	}
2226	+	else if (U.compareAndSwapInt(this, SIZECTL, sc, -2))
2227	+	transfer(tab, null);
2228	+	s = sumCount();
2229	+	}
2230	+	}
2231	+	}
2232	+
2233	+	/**
2234	+	* Helps transfer if a resize is in progress.
2235	+	*/
2236	+	final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) {
2237	+	Node<K,V>[] nextTab; int sc;
2238	+	if ((f instanceof ForwardingNode) &&
2239	+	(nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) {
2240	+	if (nextTab == nextTable && tab == table &&
2241	+	transferIndex > transferOrigin && (sc = sizeCtl) < -1 &&
2242	+	U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2243	+	transfer(tab, nextTab);
2244	+	return nextTab;
2245	+	}
2246	+	return table;
2247	+	}
2248	+
2249	+	/**
2250	+	* Tries to presize table to accommodate the given number of elements.
2251	+	*
2252	+	* @param size number of elements (doesn't need to be perfectly accurate)
2253	+	*/
2254	+	private final void tryPresize(int size) {
2255	+	int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
2256	+	tableSizeFor(size + (size >>> 1) + 1);
2257	+	int sc;
2258	+	while ((sc = sizeCtl) >= 0) {
2259	+	Node<K,V>[] tab = table; int n;
2260	+	if (tab == null || (n = tab.length) == 0) {
2261	+	n = (sc > c) ? sc : c;
2262	+	if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2263	+	try {
2264	+	if (table == tab) {
2265	+	@SuppressWarnings({"rawtypes","unchecked"})
2266	+	Node<K,V>[] nt = (Node<K,V>[])new Node[n];
2267	+	table = nt;
2268	+	sc = n - (n >>> 2);
2269	+	}
2270	+	} finally {
2271	+	sizeCtl = sc;
2272		}
2273		}
2274		}
2275	<	if (check == sum)
2275	>	else if (c <= sc || n >= MAXIMUM_CAPACITY)
2276		break;
2277	+	else if (tab == table &&
2278	+	U.compareAndSwapInt(this, SIZECTL, sc, -2))
2279	+	transfer(tab, null);
2280	+	}
2281	+	}
2282	+
2283	+	/**
2284	+	* Moves and/or copies the nodes in each bin to new table. See
2285	+	* above for explanation.
2286	+	*/
2287	+	private final void transfer(Node<K,V>[] tab, Node<K,V>[] nextTab) {
2288	+	int n = tab.length, stride;
2289	+	if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
2290	+	stride = MIN_TRANSFER_STRIDE; // subdivide range
2291	+	if (nextTab == null) {            // initiating
2292	+	try {
2293	+	@SuppressWarnings({"rawtypes","unchecked"})
2294	+	Node<K,V>[] nt = (Node<K,V>[])new Node[n << 1];
2295	+	nextTab = nt;
2296	+	} catch (Throwable ex) {      // try to cope with OOME
2297	+	sizeCtl = Integer.MAX_VALUE;
2298	+	return;
2299	+	}
2300	+	nextTable = nextTab;
2301	+	transferOrigin = n;
2302	+	transferIndex = n;
2303	+	ForwardingNode<K,V> rev = new ForwardingNode<K,V>(tab);
2304	+	for (int k = n; k > 0;) {    // progressively reveal ready slots
2305	+	int nextk = (k > stride) ? k - stride : 0;
2306	+	for (int m = nextk; m < k; ++m)
2307	+	nextTab[m] = rev;
2308	+	for (int m = n + nextk; m < n + k; ++m)
2309	+	nextTab[m] = rev;
2310	+	U.putOrderedInt(this, TRANSFERORIGIN, k = nextk);
2311	+	}
2312	+	}
2313	+	int nextn = nextTab.length;
2314	+	ForwardingNode<K,V> fwd = new ForwardingNode<K,V>(nextTab);
2315	+	boolean advance = true;
2316	+	boolean finishing = false; // to ensure sweep before committing nextTab
2317	+	for (int i = 0, bound = 0;;) {
2318	+	int nextIndex, nextBound, fh; Node<K,V> f;
2319	+	while (advance) {
2320	+	if (--i >= bound || finishing)
2321	+	advance = false;
2322	+	else if ((nextIndex = transferIndex) <= transferOrigin) {
2323	+	i = -1;
2324	+	advance = false;
2325	+	}
2326	+	else if (U.compareAndSwapInt
2327	+	(this, TRANSFERINDEX, nextIndex,
2328	+	nextBound = (nextIndex > stride ?
2329	+	nextIndex - stride : 0))) {
2330	+	bound = nextBound;
2331	+	i = nextIndex - 1;
2332	+	advance = false;
2333	+	}
2334	+	}
2335	+	if (i < 0 || i >= n || i + n >= nextn) {
2336	+	if (finishing) {
2337	+	nextTable = null;
2338	+	table = nextTab;
2339	+	sizeCtl = (n << 1) - (n >>> 1);
2340	+	return;
2341	+	}
2342	+	for (int sc;;) {
2343	+	if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) {
2344	+	if (sc != -1)
2345	+	return;
2346	+	finishing = advance = true;
2347	+	i = n; // recheck before commit
2348	+	break;
2349	+	}
2350	+	}
2351	+	}
2352	+	else if ((f = tabAt(tab, i)) == null) {
2353	+	if (casTabAt(tab, i, null, fwd)) {
2354	+	setTabAt(nextTab, i, null);
2355	+	setTabAt(nextTab, i + n, null);
2356	+	advance = true;
2357	+	}
2358	+	}
2359	+	else if ((fh = f.hash) == MOVED)
2360	+	advance = true; // already processed
2361	+	else {
2362	+	synchronized (f) {
2363	+	if (tabAt(tab, i) == f) {
2364	+	Node<K,V> ln, hn;
2365	+	if (fh >= 0) {
2366	+	int runBit = fh & n;
2367	+	Node<K,V> lastRun = f;
2368	+	for (Node<K,V> p = f.next; p != null; p = p.next) {
2369	+	int b = p.hash & n;
2370	+	if (b != runBit) {
2371	+	runBit = b;
2372	+	lastRun = p;
2373	+	}
2374	+	}
2375	+	if (runBit == 0) {
2376	+	ln = lastRun;
2377	+	hn = null;
2378	+	}
2379	+	else {
2380	+	hn = lastRun;
2381	+	ln = null;
2382	+	}
2383	+	for (Node<K,V> p = f; p != lastRun; p = p.next) {
2384	+	int ph = p.hash; K pk = p.key; V pv = p.val;
2385	+	if ((ph & n) == 0)
2386	+	ln = new Node<K,V>(ph, pk, pv, ln);
2387	+	else
2388	+	hn = new Node<K,V>(ph, pk, pv, hn);
2389	+	}
2390	+	setTabAt(nextTab, i, ln);
2391	+	setTabAt(nextTab, i + n, hn);
2392	+	setTabAt(tab, i, fwd);
2393	+	advance = true;
2394	+	}
2395	+	else if (f instanceof TreeBin) {
2396	+	TreeBin<K,V> t = (TreeBin<K,V>)f;
2397	+	TreeNode<K,V> lo = null, loTail = null;
2398	+	TreeNode<K,V> hi = null, hiTail = null;
2399	+	int lc = 0, hc = 0;
2400	+	for (Node<K,V> e = t.first; e != null; e = e.next) {
2401	+	int h = e.hash;
2402	+	TreeNode<K,V> p = new TreeNode<K,V>
2403	+	(h, e.key, e.val, null, null);
2404	+	if ((h & n) == 0) {
2405	+	if ((p.prev = loTail) == null)
2406	+	lo = p;
2407	+	else
2408	+	loTail.next = p;
2409	+	loTail = p;
2410	+	++lc;
2411	+	}
2412	+	else {
2413	+	if ((p.prev = hiTail) == null)
2414	+	hi = p;
2415	+	else
2416	+	hiTail.next = p;
2417	+	hiTail = p;
2418	+	++hc;
2419	+	}
2420	+	}
2421	+	ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) :
2422	+	(hc != 0) ? new TreeBin<K,V>(lo) : t;
2423	+	hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
2424	+	(lc != 0) ? new TreeBin<K,V>(hi) : t;
2425	+	setTabAt(nextTab, i, ln);
2426	+	setTabAt(nextTab, i + n, hn);
2427	+	setTabAt(tab, i, fwd);
2428	+	advance = true;
2429	+	}
2430	+	}
2431	+	}
2432	+	}
2433		}
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;
2434		}
2435
2436	+	/* ---------------- Counter support -------------- */
2437
2438		/**
2439	<	* Returns the value to which the specified key is mapped in this table.
2440	<	*
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>.
2439	>	* A padded cell for distributing counts.  Adapted from LongAdder
2440	>	* and Striped64.  See their internal docs for explanation.
2441		*/
2442	<	public V get(Object key) {
2443	<	int hash = hash(key); // throws NullPointerException if key null
2444	<	return segmentFor(hash).get(key, hash);
2442	>	@sun.misc.Contended static final class CounterCell {
2443	>	volatile long value;
2444	>	CounterCell(long x) { value = x; }
2445	>	}
2446	>
2447	>	final long sumCount() {
2448	>	CounterCell[] as = counterCells; CounterCell a;
2449	>	long sum = baseCount;
2450	>	if (as != null) {
2451	>	for (int i = 0; i < as.length; ++i) {
2452	>	if ((a = as[i]) != null)
2453	>	sum += a.value;
2454	>	}
2455	>	}
2456	>	return sum;
2457	>	}
2458	>
2459	>	// See LongAdder version for explanation
2460	>	private final void fullAddCount(long x, boolean wasUncontended) {
2461	>	int h;
2462	>	if ((h = ThreadLocalRandom.getProbe()) == 0) {
2463	>	ThreadLocalRandom.localInit();      // force initialization
2464	>	h = ThreadLocalRandom.getProbe();
2465	>	wasUncontended = true;
2466	>	}
2467	>	boolean collide = false;                // True if last slot nonempty
2468	>	for (;;) {
2469	>	CounterCell[] as; CounterCell a; int n; long v;
2470	>	if ((as = counterCells) != null && (n = as.length) > 0) {
2471	>	if ((a = as[(n - 1) & h]) == null) {
2472	>	if (cellsBusy == 0) {            // Try to attach new Cell
2473	>	CounterCell r = new CounterCell(x); // Optimistic create
2474	>	if (cellsBusy == 0 &&
2475	>	U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2476	>	boolean created = false;
2477	>	try {               // Recheck under lock
2478	>	CounterCell[] rs; int m, j;
2479	>	if ((rs = counterCells) != null &&
2480	>	(m = rs.length) > 0 &&
2481	>	rs[j = (m - 1) & h] == null) {
2482	>	rs[j] = r;
2483	>	created = true;
2484	>	}
2485	>	} finally {
2486	>	cellsBusy = 0;
2487	>	}
2488	>	if (created)
2489	>	break;
2490	>	continue;           // Slot is now non-empty
2491	>	}
2492	>	}
2493	>	collide = false;
2494	>	}
2495	>	else if (!wasUncontended)       // CAS already known to fail
2496	>	wasUncontended = true;      // Continue after rehash
2497	>	else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
2498	>	break;
2499	>	else if (counterCells != as || n >= NCPU)
2500	>	collide = false;            // At max size or stale
2501	>	else if (!collide)
2502	>	collide = true;
2503	>	else if (cellsBusy == 0 &&
2504	>	U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2505	>	try {
2506	>	if (counterCells == as) {// Expand table unless stale
2507	>	CounterCell[] rs = new CounterCell[n << 1];
2508	>	for (int i = 0; i < n; ++i)
2509	>	rs[i] = as[i];
2510	>	counterCells = rs;
2511	>	}
2512	>	} finally {
2513	>	cellsBusy = 0;
2514	>	}
2515	>	collide = false;
2516	>	continue;                   // Retry with expanded table
2517	>	}
2518	>	h = ThreadLocalRandom.advanceProbe(h);
2519	>	}
2520	>	else if (cellsBusy == 0 && counterCells == as &&
2521	>	U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
2522	>	boolean init = false;
2523	>	try {                           // Initialize table
2524	>	if (counterCells == as) {
2525	>	CounterCell[] rs = new CounterCell[2];
2526	>	rs[h & 1] = new CounterCell(x);
2527	>	counterCells = rs;
2528	>	init = true;
2529	>	}
2530	>	} finally {
2531	>	cellsBusy = 0;
2532	>	}
2533	>	if (init)
2534	>	break;
2535	>	}
2536	>	else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
2537	>	break;                          // Fall back on using base
2538	>	}
2539		}
2540
2541	+	/* ---------------- Conversion from/to TreeBins -------------- */
2542	+
2543		/**
2544	<	* Tests if the specified object is a key in this table.
2545	<	*
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>.
2544	>	* Replaces all linked nodes in bin at given index unless table is
2545	>	* too small, in which case resizes instead.
2546		*/
2547	<	public boolean containsKey(Object key) {
2548	<	int hash = hash(key); // throws NullPointerException if key null
2549	<	return segmentFor(hash).containsKey(key, hash);
2547	>	private final void treeifyBin(Node<K,V>[] tab, int index) {
2548	>	Node<K,V> b; int n, sc;
2549	>	if (tab != null) {
2550	>	if ((n = tab.length) < MIN_TREEIFY_CAPACITY) {
2551	>	if (tab == table && (sc = sizeCtl) >= 0 &&
2552	>	U.compareAndSwapInt(this, SIZECTL, sc, -2))
2553	>	transfer(tab, null);
2554	>	}
2555	>	else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
2556	>	synchronized (b) {
2557	>	if (tabAt(tab, index) == b) {
2558	>	TreeNode<K,V> hd = null, tl = null;
2559	>	for (Node<K,V> e = b; e != null; e = e.next) {
2560	>	TreeNode<K,V> p =
2561	>	new TreeNode<K,V>(e.hash, e.key, e.val,
2562	>	null, null);
2563	>	if ((p.prev = tl) == null)
2564	>	hd = p;
2565	>	else
2566	>	tl.next = p;
2567	>	tl = p;
2568	>	}
2569	>	setTabAt(tab, index, new TreeBin<K,V>(hd));
2570	>	}
2571	>	}
2572	>	}
2573	>	}
2574		}
2575
2576		/**
2577	<	* 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>.
2577	>	* Returns a list on non-TreeNodes replacing those in given list.
2578		*/
2579	<	public boolean containsValue(Object value) {
2580	<	if (value == null)
2581	<	throw new NullPointerException();
2582	<
2583	<	// See explanation of modCount use above
2579	>	static <K,V> Node<K,V> untreeify(Node<K,V> b) {
2580	>	Node<K,V> hd = null, tl = null;
2581	>	for (Node<K,V> q = b; q != null; q = q.next) {
2582	>	Node<K,V> p = new Node<K,V>(q.hash, q.key, q.val, null);
2583	>	if (tl == null)
2584	>	hd = p;
2585	>	else
2586	>	tl.next = p;
2587	>	tl = p;
2588	>	}
2589	>	return hd;
2590	>	}
2591
2592	<	final Segment[] segments = this.segments;
768	<	int[] mc = new int[segments.length];
2592	>	/* ---------------- TreeNodes -------------- */
2593
2594	<	// Try a few times without locking
2595	<	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
2596	<	int sum = 0;
2597	<	int mcsum = 0;
2598	<	for (int i = 0; i < segments.length; ++i) {
2599	<	int c = segments[i].count;
2600	<	mcsum += mc[i] = segments[i].modCount;
2601	<	if (segments[i].containsValue(value))
2602	<	return true;
2594	>	/**
2595	>	* Nodes for use in TreeBins
2596	>	*/
2597	>	static final class TreeNode<K,V> extends Node<K,V> {
2598	>	TreeNode<K,V> parent;  // red-black tree links
2599	>	TreeNode<K,V> left;
2600	>	TreeNode<K,V> right;
2601	>	TreeNode<K,V> prev;    // needed to unlink next upon deletion
2602	>	boolean red;
2603	>
2604	>	TreeNode(int hash, K key, V val, Node<K,V> next,
2605	>	TreeNode<K,V> parent) {
2606	>	super(hash, key, val, next);
2607	>	this.parent = parent;
2608	>	}
2609	>
2610	>	Node<K,V> find(int h, Object k) {
2611	>	return findTreeNode(h, k, null);
2612	>	}
2613	>
2614	>	/**
2615	>	* Returns the TreeNode (or null if not found) for the given key
2616	>	* starting at given root.
2617	>	*/
2618	>	final TreeNode<K,V> findTreeNode(int h, Object k, Class<?> kc) {
2619	>	if (k != null) {
2620	>	TreeNode<K,V> p = this;
2621	>	do  {
2622	>	int ph, dir; K pk; TreeNode<K,V> q;
2623	>	TreeNode<K,V> pl = p.left, pr = p.right;
2624	>	if ((ph = p.hash) > h)
2625	>	p = pl;
2626	>	else if (ph < h)
2627	>	p = pr;
2628	>	else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2629	>	return p;
2630	>	else if (pl == null)
2631	>	p = pr;
2632	>	else if (pr == null)
2633	>	p = pl;
2634	>	else if ((kc != null ||
2635	>	(kc = comparableClassFor(k)) != null) &&
2636	>	(dir = compareComparables(kc, k, pk)) != 0)
2637	>	p = (dir < 0) ? pl : pr;
2638	>	else if ((q = pr.findTreeNode(h, k, kc)) != null)
2639	>	return q;
2640	>	else
2641	>	p = pl;
2642	>	} while (p != null);
2643		}
2644	<	boolean cleanSweep = true;
2645	<	if (mcsum != 0) {
2646	<	for (int i = 0; i < segments.length; ++i) {
2647	<	int c = segments[i].count;
2648	<	if (mc[i] != segments[i].modCount) {
2649	<	cleanSweep = false;
2650	<	break;
2644	>	return null;
2645	>	}
2646	>	}
2647	>
2648	>	/* ---------------- TreeBins -------------- */
2649	>
2650	>	/**
2651	>	* TreeNodes used at the heads of bins. TreeBins do not hold user
2652	>	* keys or values, but instead point to list of TreeNodes and
2653	>	* their root. They also maintain a parasitic read-write lock
2654	>	* forcing writers (who hold bin lock) to wait for readers (who do
2655	>	* not) to complete before tree restructuring operations.
2656	>	*/
2657	>	static final class TreeBin<K,V> extends Node<K,V> {
2658	>	TreeNode<K,V> root;
2659	>	volatile TreeNode<K,V> first;
2660	>	volatile Thread waiter;
2661	>	volatile int lockState;
2662	>	// values for lockState
2663	>	static final int WRITER = 1; // set while holding write lock
2664	>	static final int WAITER = 2; // set when waiting for write lock
2665	>	static final int READER = 4; // increment value for setting read lock
2666	>
2667	>	/**
2668	>	* Tie-breaking utility for ordering insertions when equal
2669	>	* hashCodes and non-comparable. We don't require a total
2670	>	* order, just a consistent insertion rule to maintain
2671	>	* equivalence across rebalancings. Tie-breaking further than
2672	>	* necessary simplifies testing a bit.
2673	>	*/
2674	>	static int tieBreakOrder(Object a, Object b) {
2675	>	int d;
2676	>	if (a == null || b == null ||
2677	>	(d = a.getClass().getName().
2678	>	compareTo(b.getClass().getName())) == 0)
2679	>	d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
2680	>	-1 : 1);
2681	>	return d;
2682	>	}
2683	>
2684	>	/**
2685	>	* Creates bin with initial set of nodes headed by b.
2686	>	*/
2687	>	TreeBin(TreeNode<K,V> b) {
2688	>	super(TREEBIN, null, null, null);
2689	>	this.first = b;
2690	>	TreeNode<K,V> r = null;
2691	>	for (TreeNode<K,V> x = b, next; x != null; x = next) {
2692	>	next = (TreeNode<K,V>)x.next;
2693	>	x.left = x.right = null;
2694	>	if (r == null) {
2695	>	x.parent = null;
2696	>	x.red = false;
2697	>	r = x;
2698	>	}
2699	>	else {
2700	>	K k = x.key;
2701	>	int h = x.hash;
2702	>	Class<?> kc = null;
2703	>	for (TreeNode<K,V> p = r;;) {
2704	>	int dir, ph;
2705	>	K pk = p.key;
2706	>	if ((ph = p.hash) > h)
2707	>	dir = -1;
2708	>	else if (ph < h)
2709	>	dir = 1;
2710	>	else if ((kc == null &&
2711	>	(kc = comparableClassFor(k)) == null) ||
2712	>	(dir = compareComparables(kc, k, pk)) == 0)
2713	>	dir = tieBreakOrder(k, pk);
2714	>	TreeNode<K,V> xp = p;
2715	>	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2716	>	x.parent = xp;
2717	>	if (dir <= 0)
2718	>	xp.left = x;
2719	>	else
2720	>	xp.right = x;
2721	>	r = balanceInsertion(r, x);
2722	>	break;
2723	>	}
2724		}
2725		}
2726		}
2727	<	if (cleanSweep)
2728	<	return false;
2727	>	this.root = r;
2728	>	assert checkInvariants(root);
2729		}
2730	<	// Resort to locking all segments
2731	<	for (int i = 0; i < segments.length; ++i)
2732	<	segments[i].lock();
2733	<	boolean found = false;
2734	<	try {
2735	<	for (int i = 0; i < segments.length; ++i) {
2736	<	if (segments[i].containsValue(value)) {
2737	<	found = true;
2730	>
2731	>	/**
2732	>	* Acquires write lock for tree restructuring.
2733	>	*/
2734	>	private final void lockRoot() {
2735	>	if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER))
2736	>	contendedLock(); // offload to separate method
2737	>	}
2738	>
2739	>	/**
2740	>	* Releases write lock for tree restructuring.
2741	>	*/
2742	>	private final void unlockRoot() {
2743	>	lockState = 0;
2744	>	}
2745	>
2746	>	/**
2747	>	* Possibly blocks awaiting root lock.
2748	>	*/
2749	>	private final void contendedLock() {
2750	>	boolean waiting = false;
2751	>	for (int s;;) {
2752	>	if (((s = lockState) & WRITER) == 0) {
2753	>	if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
2754	>	if (waiting)
2755	>	waiter = null;
2756	>	return;
2757	>	}
2758	>	}
2759	>	else if ((s | WAITER) == 0) {
2760	>	if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
2761	>	waiting = true;
2762	>	waiter = Thread.currentThread();
2763	>	}
2764	>	}
2765	>	else if (waiting)
2766	>	LockSupport.park(this);
2767	>	}
2768	>	}
2769	>
2770	>	/**
2771	>	* Returns matching node or null if none. Tries to search
2772	>	* using tree comparisons from root, but continues linear
2773	>	* search when lock not available.
2774	>	*/
2775	>	final Node<K,V> find(int h, Object k) {
2776	>	if (k != null) {
2777	>	for (Node<K,V> e = first; e != null; e = e.next) {
2778	>	int s; K ek;
2779	>	if (((s = lockState) & (WAITER|WRITER)) != 0) {
2780	>	if (e.hash == h &&
2781	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
2782	>	return e;
2783	>	}
2784	>	else if (U.compareAndSwapInt(this, LOCKSTATE, s,
2785	>	s + READER)) {
2786	>	TreeNode<K,V> r, p;
2787	>	try {
2788	>	p = ((r = root) == null ? null :
2789	>	r.findTreeNode(h, k, null));
2790	>	} finally {
2791	>	Thread w;
2792	>	if (U.getAndAddInt(this, LOCKSTATE, -READER) ==
2793	>	(READER|WAITER) && (w = waiter) != null)
2794	>	LockSupport.unpark(w);
2795	>	}
2796	>	return p;
2797	>	}
2798	>	}
2799	>	}
2800	>	return null;
2801	>	}
2802	>
2803	>	/**
2804	>	* Finds or adds a node.
2805	>	* @return null if added
2806	>	*/
2807	>	final TreeNode<K,V> putTreeVal(int h, K k, V v) {
2808	>	Class<?> kc = null;
2809	>	boolean searched = false;
2810	>	for (TreeNode<K,V> p = root;;) {
2811	>	int dir, ph; K pk;
2812	>	if (p == null) {
2813	>	first = root = new TreeNode<K,V>(h, k, v, null, null);
2814	>	break;
2815	>	}
2816	>	else if ((ph = p.hash) > h)
2817	>	dir = -1;
2818	>	else if (ph < h)
2819	>	dir = 1;
2820	>	else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2821	>	return p;
2822	>	else if ((kc == null &&
2823	>	(kc = comparableClassFor(k)) == null) ||
2824	>	(dir = compareComparables(kc, k, pk)) == 0) {
2825	>	if (!searched) {
2826	>	TreeNode<K,V> q, ch;
2827	>	searched = true;
2828	>	if (((ch = p.left) != null &&
2829	>	(q = ch.findTreeNode(h, k, kc)) != null) ||
2830	>	((ch = p.right) != null &&
2831	>	(q = ch.findTreeNode(h, k, kc)) != null))
2832	>	return q;
2833	>	}
2834	>	dir = tieBreakOrder(k, pk);
2835	>	}
2836	>
2837	>	TreeNode<K,V> xp = p;
2838	>	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2839	>	TreeNode<K,V> x, f = first;
2840	>	first = x = new TreeNode<K,V>(h, k, v, f, xp);
2841	>	if (f != null)
2842	>	f.prev = x;
2843	>	if (dir <= 0)
2844	>	xp.left = x;
2845	>	else
2846	>	xp.right = x;
2847	>	if (!xp.red)
2848	>	x.red = true;
2849	>	else {
2850	>	lockRoot();
2851	>	try {
2852	>	root = balanceInsertion(root, x);
2853	>	} finally {
2854	>	unlockRoot();
2855	>	}
2856	>	}
2857		break;
2858		}
2859		}
2860	<	} finally {
2861	<	for (int i = 0; i < segments.length; ++i)
2862	<	segments[i].unlock();
2860	>	assert checkInvariants(root);
2861	>	return null;
2862	>	}
2863	>
2864	>	/**
2865	>	* Removes the given node, that must be present before this
2866	>	* call.  This is messier than typical red-black deletion code
2867	>	* because we cannot swap the contents of an interior node
2868	>	* with a leaf successor that is pinned by "next" pointers
2869	>	* that are accessible independently of lock. So instead we
2870	>	* swap the tree linkages.
2871	>	*
2872	>	* @return true if now too small, so should be untreeified
2873	>	*/
2874	>	final boolean removeTreeNode(TreeNode<K,V> p) {
2875	>	TreeNode<K,V> next = (TreeNode<K,V>)p.next;
2876	>	TreeNode<K,V> pred = p.prev;  // unlink traversal pointers
2877	>	TreeNode<K,V> r, rl;
2878	>	if (pred == null)
2879	>	first = next;
2880	>	else
2881	>	pred.next = next;
2882	>	if (next != null)
2883	>	next.prev = pred;
2884	>	if (first == null) {
2885	>	root = null;
2886	>	return true;
2887	>	}
2888	>	if ((r = root) == null || r.right == null || // too small
2889	>	(rl = r.left) == null || rl.left == null)
2890	>	return true;
2891	>	lockRoot();
2892	>	try {
2893	>	TreeNode<K,V> replacement;
2894	>	TreeNode<K,V> pl = p.left;
2895	>	TreeNode<K,V> pr = p.right;
2896	>	if (pl != null && pr != null) {
2897	>	TreeNode<K,V> s = pr, sl;
2898	>	while ((sl = s.left) != null) // find successor
2899	>	s = sl;
2900	>	boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2901	>	TreeNode<K,V> sr = s.right;
2902	>	TreeNode<K,V> pp = p.parent;
2903	>	if (s == pr) { // p was s's direct parent
2904	>	p.parent = s;
2905	>	s.right = p;
2906	>	}
2907	>	else {
2908	>	TreeNode<K,V> sp = s.parent;
2909	>	if ((p.parent = sp) != null) {
2910	>	if (s == sp.left)
2911	>	sp.left = p;
2912	>	else
2913	>	sp.right = p;
2914	>	}
2915	>	if ((s.right = pr) != null)
2916	>	pr.parent = s;
2917	>	}
2918	>	p.left = null;
2919	>	if ((p.right = sr) != null)
2920	>	sr.parent = p;
2921	>	if ((s.left = pl) != null)
2922	>	pl.parent = s;
2923	>	if ((s.parent = pp) == null)
2924	>	r = s;
2925	>	else if (p == pp.left)
2926	>	pp.left = s;
2927	>	else
2928	>	pp.right = s;
2929	>	if (sr != null)
2930	>	replacement = sr;
2931	>	else
2932	>	replacement = p;
2933	>	}
2934	>	else if (pl != null)
2935	>	replacement = pl;
2936	>	else if (pr != null)
2937	>	replacement = pr;
2938	>	else
2939	>	replacement = p;
2940	>	if (replacement != p) {
2941	>	TreeNode<K,V> pp = replacement.parent = p.parent;
2942	>	if (pp == null)
2943	>	r = replacement;
2944	>	else if (p == pp.left)
2945	>	pp.left = replacement;
2946	>	else
2947	>	pp.right = replacement;
2948	>	p.left = p.right = p.parent = null;
2949	>	}
2950	>
2951	>	root = (p.red) ? r : balanceDeletion(r, replacement);
2952	>
2953	>	if (p == replacement) {  // detach pointers
2954	>	TreeNode<K,V> pp;
2955	>	if ((pp = p.parent) != null) {
2956	>	if (p == pp.left)
2957	>	pp.left = null;
2958	>	else if (p == pp.right)
2959	>	pp.right = null;
2960	>	p.parent = null;
2961	>	}
2962	>	}
2963	>	} finally {
2964	>	unlockRoot();
2965	>	}
2966	>	assert checkInvariants(root);
2967	>	return false;
2968	>	}
2969	>
2970	>	/* ------------------------------------------------------------ */
2971	>	// Red-black tree methods, all adapted from CLR
2972	>
2973	>	static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2974	>	TreeNode<K,V> p) {
2975	>	TreeNode<K,V> r, pp, rl;
2976	>	if (p != null && (r = p.right) != null) {
2977	>	if ((rl = p.right = r.left) != null)
2978	>	rl.parent = p;
2979	>	if ((pp = r.parent = p.parent) == null)
2980	>	(root = r).red = false;
2981	>	else if (pp.left == p)
2982	>	pp.left = r;
2983	>	else
2984	>	pp.right = r;
2985	>	r.left = p;
2986	>	p.parent = r;
2987	>	}
2988	>	return root;
2989	>	}
2990	>
2991	>	static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2992	>	TreeNode<K,V> p) {
2993	>	TreeNode<K,V> l, pp, lr;
2994	>	if (p != null && (l = p.left) != null) {
2995	>	if ((lr = p.left = l.right) != null)
2996	>	lr.parent = p;
2997	>	if ((pp = l.parent = p.parent) == null)
2998	>	(root = l).red = false;
2999	>	else if (pp.right == p)
3000	>	pp.right = l;
3001	>	else
3002	>	pp.left = l;
3003	>	l.right = p;
3004	>	p.parent = l;
3005	>	}
3006	>	return root;
3007	>	}
3008	>
3009	>	static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
3010	>	TreeNode<K,V> x) {
3011	>	x.red = true;
3012	>	for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
3013	>	if ((xp = x.parent) == null) {
3014	>	x.red = false;
3015	>	return x;
3016	>	}
3017	>	else if (!xp.red || (xpp = xp.parent) == null)
3018	>	return root;
3019	>	if (xp == (xppl = xpp.left)) {
3020	>	if ((xppr = xpp.right) != null && xppr.red) {
3021	>	xppr.red = false;
3022	>	xp.red = false;
3023	>	xpp.red = true;
3024	>	x = xpp;
3025	>	}
3026	>	else {
3027	>	if (x == xp.right) {
3028	>	root = rotateLeft(root, x = xp);
3029	>	xpp = (xp = x.parent) == null ? null : xp.parent;
3030	>	}
3031	>	if (xp != null) {
3032	>	xp.red = false;
3033	>	if (xpp != null) {
3034	>	xpp.red = true;
3035	>	root = rotateRight(root, xpp);
3036	>	}
3037	>	}
3038	>	}
3039	>	}
3040	>	else {
3041	>	if (xppl != null && xppl.red) {
3042	>	xppl.red = false;
3043	>	xp.red = false;
3044	>	xpp.red = true;
3045	>	x = xpp;
3046	>	}
3047	>	else {
3048	>	if (x == xp.left) {
3049	>	root = rotateRight(root, x = xp);
3050	>	xpp = (xp = x.parent) == null ? null : xp.parent;
3051	>	}
3052	>	if (xp != null) {
3053	>	xp.red = false;
3054	>	if (xpp != null) {
3055	>	xpp.red = true;
3056	>	root = rotateLeft(root, xpp);
3057	>	}
3058	>	}
3059	>	}
3060	>	}
3061	>	}
3062	>	}
3063	>
3064	>	static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
3065	>	TreeNode<K,V> x) {
3066	>	for (TreeNode<K,V> xp, xpl, xpr;;)  {
3067	>	if (x == null || x == root)
3068	>	return root;
3069	>	else if ((xp = x.parent) == null) {
3070	>	x.red = false;
3071	>	return x;
3072	>	}
3073	>	else if (x.red) {
3074	>	x.red = false;
3075	>	return root;
3076	>	}
3077	>	else if ((xpl = xp.left) == x) {
3078	>	if ((xpr = xp.right) != null && xpr.red) {
3079	>	xpr.red = false;
3080	>	xp.red = true;
3081	>	root = rotateLeft(root, xp);
3082	>	xpr = (xp = x.parent) == null ? null : xp.right;
3083	>	}
3084	>	if (xpr == null)
3085	>	x = xp;
3086	>	else {
3087	>	TreeNode<K,V> sl = xpr.left, sr = xpr.right;
3088	>	if ((sr == null || !sr.red) &&
3089	>	(sl == null || !sl.red)) {
3090	>	xpr.red = true;
3091	>	x = xp;
3092	>	}
3093	>	else {
3094	>	if (sr == null || !sr.red) {
3095	>	if (sl != null)
3096	>	sl.red = false;
3097	>	xpr.red = true;
3098	>	root = rotateRight(root, xpr);
3099	>	xpr = (xp = x.parent) == null ?
3100	>	null : xp.right;
3101	>	}
3102	>	if (xpr != null) {
3103	>	xpr.red = (xp == null) ? false : xp.red;
3104	>	if ((sr = xpr.right) != null)
3105	>	sr.red = false;
3106	>	}
3107	>	if (xp != null) {
3108	>	xp.red = false;
3109	>	root = rotateLeft(root, xp);
3110	>	}
3111	>	x = root;
3112	>	}
3113	>	}
3114	>	}
3115	>	else { // symmetric
3116	>	if (xpl != null && xpl.red) {
3117	>	xpl.red = false;
3118	>	xp.red = true;
3119	>	root = rotateRight(root, xp);
3120	>	xpl = (xp = x.parent) == null ? null : xp.left;
3121	>	}
3122	>	if (xpl == null)
3123	>	x = xp;
3124	>	else {
3125	>	TreeNode<K,V> sl = xpl.left, sr = xpl.right;
3126	>	if ((sl == null || !sl.red) &&
3127	>	(sr == null || !sr.red)) {
3128	>	xpl.red = true;
3129	>	x = xp;
3130	>	}
3131	>	else {
3132	>	if (sl == null || !sl.red) {
3133	>	if (sr != null)
3134	>	sr.red = false;
3135	>	xpl.red = true;
3136	>	root = rotateLeft(root, xpl);
3137	>	xpl = (xp = x.parent) == null ?
3138	>	null : xp.left;
3139	>	}
3140	>	if (xpl != null) {
3141	>	xpl.red = (xp == null) ? false : xp.red;
3142	>	if ((sl = xpl.left) != null)
3143	>	sl.red = false;
3144	>	}
3145	>	if (xp != null) {
3146	>	xp.red = false;
3147	>	root = rotateRight(root, xp);
3148	>	}
3149	>	x = root;
3150	>	}
3151	>	}
3152	>	}
3153	>	}
3154	>	}
3155	>
3156	>	/**
3157	>	* Recursive invariant check
3158	>	*/
3159	>	static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
3160	>	TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
3161	>	tb = t.prev, tn = (TreeNode<K,V>)t.next;
3162	>	if (tb != null && tb.next != t)
3163	>	return false;
3164	>	if (tn != null && tn.prev != t)
3165	>	return false;
3166	>	if (tp != null && t != tp.left && t != tp.right)
3167	>	return false;
3168	>	if (tl != null && (tl.parent != t || tl.hash > t.hash))
3169	>	return false;
3170	>	if (tr != null && (tr.parent != t || tr.hash < t.hash))
3171	>	return false;
3172	>	if (t.red && tl != null && tl.red && tr != null && tr.red)
3173	>	return false;
3174	>	if (tl != null && !checkInvariants(tl))
3175	>	return false;
3176	>	if (tr != null && !checkInvariants(tr))
3177	>	return false;
3178	>	return true;
3179	>	}
3180	>
3181	>	private static final sun.misc.Unsafe U;
3182	>	private static final long LOCKSTATE;
3183	>	static {
3184	>	try {
3185	>	U = sun.misc.Unsafe.getUnsafe();
3186	>	Class<?> k = TreeBin.class;
3187	>	LOCKSTATE = U.objectFieldOffset
3188	>	(k.getDeclaredField("lockState"));
3189	>	} catch (Exception e) {
3190	>	throw new Error(e);
3191	>	}
3192		}
808	–	return found;
3193		}
3194
3195	+	/* ----------------Table Traversal -------------- */
3196	+
3197		/**
3198	<	* Legacy method testing if some key maps into the specified value
3199	<	* in this table.  This method is identical in functionality to
3200	<	* {@link #containsValue}, and  exists solely to ensure
3201	<	* full compatibility with class {@link java.util.Hashtable},
3202	<	* which supported this method prior to introduction of the
3203	<	* Java Collections framework.
3198	>	* Encapsulates traversal for methods such as containsValue; also
3199	>	* serves as a base class for other iterators and spliterators.
3200	>	*
3201	>	* Method advance visits once each still-valid node that was
3202	>	* reachable upon iterator construction. It might miss some that
3203	>	* were added to a bin after the bin was visited, which is OK wrt
3204	>	* consistency guarantees. Maintaining this property in the face
3205	>	* of possible ongoing resizes requires a fair amount of
3206	>	* bookkeeping state that is difficult to optimize away amidst
3207	>	* volatile accesses.  Even so, traversal maintains reasonable
3208	>	* throughput.
3209	>	*
3210	>	* Normally, iteration proceeds bin-by-bin traversing lists.
3211	>	* However, if the table has been resized, then all future steps
3212	>	* must traverse both the bin at the current index as well as at
3213	>	* (index + baseSize); and so on for further resizings. To
3214	>	* paranoically cope with potential sharing by users of iterators
3215	>	* across threads, iteration terminates if a bounds checks fails
3216	>	* for a table read.
3217	>	*/
3218	>	static class Traverser<K,V> {
3219	>	Node<K,V>[] tab;        // current table; updated if resized
3220	>	Node<K,V> next;         // the next entry to use
3221	>	int index;              // index of bin to use next
3222	>	int baseIndex;          // current index of initial table
3223	>	int baseLimit;          // index bound for initial table
3224	>	final int baseSize;     // initial table size
3225	>
3226	>	Traverser(Node<K,V>[] tab, int size, int index, int limit) {
3227	>	this.tab = tab;
3228	>	this.baseSize = size;
3229	>	this.baseIndex = this.index = index;
3230	>	this.baseLimit = limit;
3231	>	this.next = null;
3232	>	}
3233	>
3234	>	/**
3235	>	* Advances if possible, returning next valid node, or null if none.
3236	>	*/
3237	>	final Node<K,V> advance() {
3238	>	Node<K,V> e;
3239	>	if ((e = next) != null)
3240	>	e = e.next;
3241	>	for (;;) {
3242	>	Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
3243	>	if (e != null)
3244	>	return next = e;
3245	>	if (baseIndex >= baseLimit || (t = tab) == null ||
3246	>	(n = t.length) <= (i = index) || i < 0)
3247	>	return next = null;
3248	>	if ((e = tabAt(t, index)) != null && e.hash < 0) {
3249	>	if (e instanceof ForwardingNode) {
3250	>	tab = ((ForwardingNode<K,V>)e).nextTable;
3251	>	e = null;
3252	>	continue;
3253	>	}
3254	>	else if (e instanceof TreeBin)
3255	>	e = ((TreeBin<K,V>)e).first;
3256	>	else
3257	>	e = null;
3258	>	}
3259	>	if ((index += baseSize) >= n)
3260	>	index = ++baseIndex;    // visit upper slots if present
3261	>	}
3262	>	}
3263	>	}
3264
3265	<	* @param      value   a value to search for.
3266	<	* @return     <tt>true</tt> if and only if some key maps to the
3267	<	*             <tt>value</tt> argument in this table as
822	<	*             determined by the <tt>equals</tt> method;
823	<	*             <tt>false</tt> otherwise.
824	<	* @throws  NullPointerException  if the value is <tt>null</tt>.
3265	>	/**
3266	>	* Base of key, value, and entry Iterators. Adds fields to
3267	>	* Traverser to support iterator.remove.
3268		*/
3269	<	public boolean contains(Object value) {
3270	<	return containsValue(value);
3269	>	static class BaseIterator<K,V> extends Traverser<K,V> {
3270	>	final ConcurrentHashMap<K,V> map;
3271	>	Node<K,V> lastReturned;
3272	>	BaseIterator(Node<K,V>[] tab, int size, int index, int limit,
3273	>	ConcurrentHashMap<K,V> map) {
3274	>	super(tab, size, index, limit);
3275	>	this.map = map;
3276	>	advance();
3277	>	}
3278	>
3279	>	public final boolean hasNext() { return next != null; }
3280	>	public final boolean hasMoreElements() { return next != null; }
3281	>
3282	>	public final void remove() {
3283	>	Node<K,V> p;
3284	>	if ((p = lastReturned) == null)
3285	>	throw new IllegalStateException();
3286	>	lastReturned = null;
3287	>	map.replaceNode(p.key, null, null);
3288	>	}
3289	>	}
3290	>
3291	>	static final class KeyIterator<K,V> extends BaseIterator<K,V>
3292	>	implements Iterator<K>, Enumeration<K> {
3293	>	KeyIterator(Node<K,V>[] tab, int index, int size, int limit,
3294	>	ConcurrentHashMap<K,V> map) {
3295	>	super(tab, index, size, limit, map);
3296	>	}
3297	>
3298	>	public final K next() {
3299	>	Node<K,V> p;
3300	>	if ((p = next) == null)
3301	>	throw new NoSuchElementException();
3302	>	K k = p.key;
3303	>	lastReturned = p;
3304	>	advance();
3305	>	return k;
3306	>	}
3307	>
3308	>	public final K nextElement() { return next(); }
3309		}
3310
3311	+	static final class ValueIterator<K,V> extends BaseIterator<K,V>
3312	+	implements Iterator<V>, Enumeration<V> {
3313	+	ValueIterator(Node<K,V>[] tab, int index, int size, int limit,
3314	+	ConcurrentHashMap<K,V> map) {
3315	+	super(tab, index, size, limit, map);
3316	+	}
3317	+
3318	+	public final V next() {
3319	+	Node<K,V> p;
3320	+	if ((p = next) == null)
3321	+	throw new NoSuchElementException();
3322	+	V v = p.val;
3323	+	lastReturned = p;
3324	+	advance();
3325	+	return v;
3326	+	}
3327	+
3328	+	public final V nextElement() { return next(); }
3329	+	}
3330	+
3331	+	static final class EntryIterator<K,V> extends BaseIterator<K,V>
3332	+	implements Iterator<Map.Entry<K,V>> {
3333	+	EntryIterator(Node<K,V>[] tab, int index, int size, int limit,
3334	+	ConcurrentHashMap<K,V> map) {
3335	+	super(tab, index, size, limit, map);
3336	+	}
3337	+
3338	+	public final Map.Entry<K,V> next() {
3339	+	Node<K,V> p;
3340	+	if ((p = next) == null)
3341	+	throw new NoSuchElementException();
3342	+	K k = p.key;
3343	+	V v = p.val;
3344	+	lastReturned = p;
3345	+	advance();
3346	+	return new MapEntry<K,V>(k, v, map);
3347	+	}
3348	+	}
3349	+
3350	+	/**
3351	+	* Exported Entry for EntryIterator
3352	+	*/
3353	+	static final class MapEntry<K,V> implements Map.Entry<K,V> {
3354	+	final K key; // non-null
3355	+	V val;       // non-null
3356	+	final ConcurrentHashMap<K,V> map;
3357	+	MapEntry(K key, V val, ConcurrentHashMap<K,V> map) {
3358	+	this.key = key;
3359	+	this.val = val;
3360	+	this.map = map;
3361	+	}
3362	+	public K getKey()        { return key; }
3363	+	public V getValue()      { return val; }
3364	+	public int hashCode()    { return key.hashCode() ^ val.hashCode(); }
3365	+	public String toString() { return key + "=" + val; }
3366	+
3367	+	public boolean equals(Object o) {
3368	+	Object k, v; Map.Entry<?,?> e;
3369	+	return ((o instanceof Map.Entry) &&
3370	+	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
3371	+	(v = e.getValue()) != null &&
3372	+	(k == key || k.equals(key)) &&
3373	+	(v == val || v.equals(val)));
3374	+	}
3375	+
3376	+	/**
3377	+	* Sets our entry's value and writes through to the map. The
3378	+	* value to return is somewhat arbitrary here. Since we do not
3379	+	* necessarily track asynchronous changes, the most recent
3380	+	* "previous" value could be different from what we return (or
3381	+	* could even have been removed, in which case the put will
3382	+	* re-establish). We do not and cannot guarantee more.
3383	+	*/
3384	+	public V setValue(V value) {
3385	+	if (value == null) throw new NullPointerException();
3386	+	V v = val;
3387	+	val = value;
3388	+	map.put(key, value);
3389	+	return v;
3390	+	}
3391	+	}
3392	+
3393	+	static final class KeySpliterator<K,V> extends Traverser<K,V>
3394	+	implements Spliterator<K> {
3395	+	long est;               // size estimate
3396	+	KeySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3397	+	long est) {
3398	+	super(tab, size, index, limit);
3399	+	this.est = est;
3400	+	}
3401	+
3402	+	public Spliterator<K> trySplit() {
3403	+	int i, f, h;
3404	+	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3405	+	new KeySpliterator<K,V>(tab, baseSize, baseLimit = h,
3406	+	f, est >>>= 1);
3407	+	}
3408	+
3409	+	public void forEachRemaining(Consumer<? super K> action) {
3410	+	if (action == null) throw new NullPointerException();
3411	+	for (Node<K,V> p; (p = advance()) != null;)
3412	+	action.accept(p.key);
3413	+	}
3414	+
3415	+	public boolean tryAdvance(Consumer<? super K> action) {
3416	+	if (action == null) throw new NullPointerException();
3417	+	Node<K,V> p;
3418	+	if ((p = advance()) == null)
3419	+	return false;
3420	+	action.accept(p.key);
3421	+	return true;
3422	+	}
3423	+
3424	+	public long estimateSize() { return est; }
3425	+
3426	+	public int characteristics() {
3427	+	return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3428	+	Spliterator.NONNULL;
3429	+	}
3430	+	}
3431	+
3432	+	static final class ValueSpliterator<K,V> extends Traverser<K,V>
3433	+	implements Spliterator<V> {
3434	+	long est;               // size estimate
3435	+	ValueSpliterator(Node<K,V>[] tab, int size, int index, int limit,
3436	+	long est) {
3437	+	super(tab, size, index, limit);
3438	+	this.est = est;
3439	+	}
3440	+
3441	+	public Spliterator<V> trySplit() {
3442	+	int i, f, h;
3443	+	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3444	+	new ValueSpliterator<K,V>(tab, baseSize, baseLimit = h,
3445	+	f, est >>>= 1);
3446	+	}
3447	+
3448	+	public void forEachRemaining(Consumer<? super V> action) {
3449	+	if (action == null) throw new NullPointerException();
3450	+	for (Node<K,V> p; (p = advance()) != null;)
3451	+	action.accept(p.val);
3452	+	}
3453	+
3454	+	public boolean tryAdvance(Consumer<? super V> action) {
3455	+	if (action == null) throw new NullPointerException();
3456	+	Node<K,V> p;
3457	+	if ((p = advance()) == null)
3458	+	return false;
3459	+	action.accept(p.val);
3460	+	return true;
3461	+	}
3462	+
3463	+	public long estimateSize() { return est; }
3464	+
3465	+	public int characteristics() {
3466	+	return Spliterator.CONCURRENT | Spliterator.NONNULL;
3467	+	}
3468	+	}
3469	+
3470	+	static final class EntrySpliterator<K,V> extends Traverser<K,V>
3471	+	implements Spliterator<Map.Entry<K,V>> {
3472	+	final ConcurrentHashMap<K,V> map; // To export MapEntry
3473	+	long est;               // size estimate
3474	+	EntrySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3475	+	long est, ConcurrentHashMap<K,V> map) {
3476	+	super(tab, size, index, limit);
3477	+	this.map = map;
3478	+	this.est = est;
3479	+	}
3480	+
3481	+	public Spliterator<Map.Entry<K,V>> trySplit() {
3482	+	int i, f, h;
3483	+	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3484	+	new EntrySpliterator<K,V>(tab, baseSize, baseLimit = h,
3485	+	f, est >>>= 1, map);
3486	+	}
3487	+
3488	+	public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
3489	+	if (action == null) throw new NullPointerException();
3490	+	for (Node<K,V> p; (p = advance()) != null; )
3491	+	action.accept(new MapEntry<K,V>(p.key, p.val, map));
3492	+	}
3493	+
3494	+	public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
3495	+	if (action == null) throw new NullPointerException();
3496	+	Node<K,V> p;
3497	+	if ((p = advance()) == null)
3498	+	return false;
3499	+	action.accept(new MapEntry<K,V>(p.key, p.val, map));
3500	+	return true;
3501	+	}
3502	+
3503	+	public long estimateSize() { return est; }
3504	+
3505	+	public int characteristics() {
3506	+	return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3507	+	Spliterator.NONNULL;
3508	+	}
3509	+	}
3510	+
3511	+	// Parallel bulk operations
3512	+
3513		/**
3514	<	* Maps the specified <tt>key</tt> to the specified
3515	<	* <tt>value</tt> in this table. Neither the key nor the
3516	<	* value can be <tt>null</tt>.
3514	>	* Computes initial batch value for bulk tasks. The returned value
3515	>	* is approximately exp2 of the number of times (minus one) to
3516	>	* split task by two before executing leaf action. This value is
3517	>	* faster to compute and more convenient to use as a guide to
3518	>	* splitting than is the depth, since it is used while dividing by
3519	>	* two anyway.
3520	>	*/
3521	>	final int batchFor(long b) {
3522	>	long n;
3523	>	if (b == Long.MAX_VALUE || (n = sumCount()) <= 1L || n < b)
3524	>	return 0;
3525	>	int sp = ForkJoinPool.getCommonPoolParallelism() << 2; // slack of 4
3526	>	return (b <= 0L || (n /= b) >= sp) ? sp : (int)n;
3527	>	}
3528	>
3529	>	/**
3530	>	* Performs the given action for each (key, value).
3531		*
3532	<	* <p> The value can be retrieved by calling the <tt>get</tt> method
3533	<	* with a key that is equal to the original key.
3532	>	* @param parallelismThreshold the (estimated) number of elements
3533	>	* needed for this operation to be executed in parallel
3534	>	* @param action the action
3535	>	* @since 1.8
3536	>	*/
3537	>	public void forEach(long parallelismThreshold,
3538	>	BiConsumer<? super K,? super V> action) {
3539	>	if (action == null) throw new NullPointerException();
3540	>	new ForEachMappingTask<K,V>
3541	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3542	>	action).invoke();
3543	>	}
3544	>
3545	>	/**
3546	>	* Performs the given action for each non-null transformation
3547	>	* of each (key, value).
3548		*
3549	<	* @param      key     the table key.
3550	<	* @param      value   the value.
3551	<	* @return     the previous value of the specified key in this table,
3552	<	*             or <tt>null</tt> if it did not have one.
3553	<	* @throws  NullPointerException  if the key or value is
3554	<	*               <tt>null</tt>.
3549	>	* @param parallelismThreshold the (estimated) number of elements
3550	>	* needed for this operation to be executed in parallel
3551	>	* @param transformer a function returning the transformation
3552	>	* for an element, or null if there is no transformation (in
3553	>	* which case the action is not applied)
3554	>	* @param action the action
3555	>	* @param <U> the return type of the transformer
3556	>	* @since 1.8
3557		*/
3558	<	public V put(K key, V value) {
3559	<	if (value == null)
3558	>	public <U> void forEach(long parallelismThreshold,
3559	>	BiFunction<? super K, ? super V, ? extends U> transformer,
3560	>	Consumer<? super U> action) {
3561	>	if (transformer == null || action == null)
3562		throw new NullPointerException();
3563	<	int hash = hash(key);
3564	<	return segmentFor(hash).put(key, hash, value, false);
3563	>	new ForEachTransformedMappingTask<K,V,U>
3564	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3565	>	transformer, action).invoke();
3566		}
3567
3568		/**
3569	<	* If the specified key is not already associated
3570	<	* with a value, associate it with the given value.
3571	<	* This is equivalent to
3572	<	* <pre>
3573	<	*   if (!map.containsKey(key))
3574	<	*      return map.put(key, value);
3575	<	*   else
3576	<	*      return map.get(key);
3577	<	* </pre>
3578	<	* Except that the action is performed atomically.
3579	<	* @param key key with which the specified value is to be associated.
3580	<	* @param value value to be associated with the specified key.
3581	<	* @return previous value associated with specified key, or <tt>null</tt>
3582	<	*         if there was no mapping for key.
867	<	* @throws NullPointerException if the specified key or value is
868	<	*            <tt>null</tt>.
3569	>	* Returns a non-null result from applying the given search
3570	>	* function on each (key, value), or null if none.  Upon
3571	>	* success, further element processing is suppressed and the
3572	>	* results of any other parallel invocations of the search
3573	>	* function are ignored.
3574	>	*
3575	>	* @param parallelismThreshold the (estimated) number of elements
3576	>	* needed for this operation to be executed in parallel
3577	>	* @param searchFunction a function returning a non-null
3578	>	* result on success, else null
3579	>	* @param <U> the return type of the search function
3580	>	* @return a non-null result from applying the given search
3581	>	* function on each (key, value), or null if none
3582	>	* @since 1.8
3583		*/
3584	<	public V putIfAbsent(K key, V value) {
3585	<	if (value == null)
3584	>	public <U> U search(long parallelismThreshold,
3585	>	BiFunction<? super K, ? super V, ? extends U> searchFunction) {
3586	>	if (searchFunction == null) throw new NullPointerException();
3587	>	return new SearchMappingsTask<K,V,U>
3588	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3589	>	searchFunction, new AtomicReference<U>()).invoke();
3590	>	}
3591	>
3592	>	/**
3593	>	* Returns the result of accumulating the given transformation
3594	>	* of all (key, value) pairs using the given reducer to
3595	>	* combine values, or null if none.
3596	>	*
3597	>	* @param parallelismThreshold the (estimated) number of elements
3598	>	* needed for this operation to be executed in parallel
3599	>	* @param transformer a function returning the transformation
3600	>	* for an element, or null if there is no transformation (in
3601	>	* which case it is not combined)
3602	>	* @param reducer a commutative associative combining function
3603	>	* @param <U> the return type of the transformer
3604	>	* @return the result of accumulating the given transformation
3605	>	* of all (key, value) pairs
3606	>	* @since 1.8
3607	>	*/
3608	>	public <U> U reduce(long parallelismThreshold,
3609	>	BiFunction<? super K, ? super V, ? extends U> transformer,
3610	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3611	>	if (transformer == null || reducer == null)
3612		throw new NullPointerException();
3613	<	int hash = hash(key);
3614	<	return segmentFor(hash).put(key, hash, value, true);
3613	>	return new MapReduceMappingsTask<K,V,U>
3614	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3615	>	null, transformer, reducer).invoke();
3616		}
3617
3618	+	/**
3619	+	* Returns the result of accumulating the given transformation
3620	+	* of all (key, value) pairs using the given reducer to
3621	+	* combine values, and the given basis as an identity value.
3622	+	*
3623	+	* @param parallelismThreshold the (estimated) number of elements
3624	+	* needed for this operation to be executed in parallel
3625	+	* @param transformer a function returning the transformation
3626	+	* for an element
3627	+	* @param basis the identity (initial default value) for the reduction
3628	+	* @param reducer a commutative associative combining function
3629	+	* @return the result of accumulating the given transformation
3630	+	* of all (key, value) pairs
3631	+	* @since 1.8
3632	+	*/
3633	+	public double reduceToDouble(long parallelismThreshold,
3634	+	ToDoubleBiFunction<? super K, ? super V> transformer,
3635	+	double basis,
3636	+	DoubleBinaryOperator reducer) {
3637	+	if (transformer == null || reducer == null)
3638	+	throw new NullPointerException();
3639	+	return new MapReduceMappingsToDoubleTask<K,V>
3640	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3641	+	null, transformer, basis, reducer).invoke();
3642	+	}
3643
3644		/**
3645	<	* Copies all of the mappings from the specified map to this one.
3645	>	* Returns the result of accumulating the given transformation
3646	>	* of all (key, value) pairs using the given reducer to
3647	>	* combine values, and the given basis as an identity value.
3648		*
3649	<	* These mappings replace any mappings that this map had for any of the
3650	<	* keys currently in the specified Map.
3649	>	* @param parallelismThreshold the (estimated) number of elements
3650	>	* needed for this operation to be executed in parallel
3651	>	* @param transformer a function returning the transformation
3652	>	* for an element
3653	>	* @param basis the identity (initial default value) for the reduction
3654	>	* @param reducer a commutative associative combining function
3655	>	* @return the result of accumulating the given transformation
3656	>	* of all (key, value) pairs
3657	>	* @since 1.8
3658	>	*/
3659	>	public long reduceToLong(long parallelismThreshold,
3660	>	ToLongBiFunction<? super K, ? super V> transformer,
3661	>	long basis,
3662	>	LongBinaryOperator reducer) {
3663	>	if (transformer == null || reducer == null)
3664	>	throw new NullPointerException();
3665	>	return new MapReduceMappingsToLongTask<K,V>
3666	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3667	>	null, transformer, basis, reducer).invoke();
3668	>	}
3669	>
3670	>	/**
3671	>	* Returns the result of accumulating the given transformation
3672	>	* of all (key, value) pairs using the given reducer to
3673	>	* combine values, and the given basis as an identity value.
3674		*
3675	<	* @param t Mappings to be stored in this map.
3675	>	* @param parallelismThreshold the (estimated) number of elements
3676	>	* needed for this operation to be executed in parallel
3677	>	* @param transformer a function returning the transformation
3678	>	* for an element
3679	>	* @param basis the identity (initial default value) for the reduction
3680	>	* @param reducer a commutative associative combining function
3681	>	* @return the result of accumulating the given transformation
3682	>	* of all (key, value) pairs
3683	>	* @since 1.8
3684		*/
3685	<	public void putAll(Map<? extends K, ? extends V> t) {
3686	<	for (Iterator<? extends Map.Entry<? extends K, ? extends V>> it = (Iterator<? extends Map.Entry<? extends K, ? extends V>>) t.entrySet().iterator(); it.hasNext(); ) {
3687	<	Entry<? extends K, ? extends V> e = it.next();
3688	<	put(e.getKey(), e.getValue());
3689	<	}
3685	>	public int reduceToInt(long parallelismThreshold,
3686	>	ToIntBiFunction<? super K, ? super V> transformer,
3687	>	int basis,
3688	>	IntBinaryOperator reducer) {
3689	>	if (transformer == null || reducer == null)
3690	>	throw new NullPointerException();
3691	>	return new MapReduceMappingsToIntTask<K,V>
3692	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3693	>	null, transformer, basis, reducer).invoke();
3694		}
3695
3696		/**
3697	<	* Removes the key (and its corresponding value) from this
895	<	* table. This method does nothing if the key is not in the table.
3697	>	* Performs the given action for each key.
3698		*
3699	<	* @param   key   the key that needs to be removed.
3700	<	* @return  the value to which the key had been mapped in this table,
3701	<	*          or <tt>null</tt> if the key did not have a mapping.
3702	<	* @throws  NullPointerException  if the key is
901	<	*               <tt>null</tt>.
3699	>	* @param parallelismThreshold the (estimated) number of elements
3700	>	* needed for this operation to be executed in parallel
3701	>	* @param action the action
3702	>	* @since 1.8
3703		*/
3704	<	public V remove(Object key) {
3705	<	int hash = hash(key);
3706	<	return segmentFor(hash).remove(key, hash, null);
3704	>	public void forEachKey(long parallelismThreshold,
3705	>	Consumer<? super K> action) {
3706	>	if (action == null) throw new NullPointerException();
3707	>	new ForEachKeyTask<K,V>
3708	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3709	>	action).invoke();
3710		}
3711
3712		/**
3713	<	* Remove entry for key only if currently mapped to given value.
3714	<	* Acts as
3715	<	* <pre>
3716	<	*  if (map.get(key).equals(value)) {
3717	<	*     map.remove(key);
3718	<	*     return true;
3719	<	* } else return false;
3720	<	* </pre>
3721	<	* except that the action is performed atomically.
3722	<	* @param key key with which the specified value is associated.
3723	<	* @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>.
3713	>	* Performs the given action for each non-null transformation
3714	>	* of each key.
3715	>	*
3716	>	* @param parallelismThreshold the (estimated) number of elements
3717	>	* needed for this operation to be executed in parallel
3718	>	* @param transformer a function returning the transformation
3719	>	* for an element, or null if there is no transformation (in
3720	>	* which case the action is not applied)
3721	>	* @param action the action
3722	>	* @param <U> the return type of the transformer
3723	>	* @since 1.8
3724		*/
3725	<	public boolean remove(Object key, Object value) {
3726	<	int hash = hash(key);
3727	<	return segmentFor(hash).remove(key, hash, value) != null;
3725	>	public <U> void forEachKey(long parallelismThreshold,
3726	>	Function<? super K, ? extends U> transformer,
3727	>	Consumer<? super U> action) {
3728	>	if (transformer == null || action == null)
3729	>	throw new NullPointerException();
3730	>	new ForEachTransformedKeyTask<K,V,U>
3731	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3732	>	transformer, action).invoke();
3733		}
3734
3735	+	/**
3736	+	* Returns a non-null result from applying the given search
3737	+	* function on each key, or null if none. Upon success,
3738	+	* further element processing is suppressed and the results of
3739	+	* any other parallel invocations of the search function are
3740	+	* ignored.
3741	+	*
3742	+	* @param parallelismThreshold the (estimated) number of elements
3743	+	* needed for this operation to be executed in parallel
3744	+	* @param searchFunction a function returning a non-null
3745	+	* result on success, else null
3746	+	* @param <U> the return type of the search function
3747	+	* @return a non-null result from applying the given search
3748	+	* function on each key, or null if none
3749	+	* @since 1.8
3750	+	*/
3751	+	public <U> U searchKeys(long parallelismThreshold,
3752	+	Function<? super K, ? extends U> searchFunction) {
3753	+	if (searchFunction == null) throw new NullPointerException();
3754	+	return new SearchKeysTask<K,V,U>
3755	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3756	+	searchFunction, new AtomicReference<U>()).invoke();
3757	+	}
3758
3759		/**
3760	<	* Replace entry for key only if currently mapped to given value.
3761	<	* Acts as
3762	<	* <pre>
3763	<	*  if (map.get(key).equals(oldValue)) {
3764	<	*     map.put(key, newValue);
3765	<	*     return true;
3766	<	* } else return false;
3767	<	* </pre>
3768	<	* 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>.
3760	>	* Returns the result of accumulating all keys using the given
3761	>	* reducer to combine values, or null if none.
3762	>	*
3763	>	* @param parallelismThreshold the (estimated) number of elements
3764	>	* needed for this operation to be executed in parallel
3765	>	* @param reducer a commutative associative combining function
3766	>	* @return the result of accumulating all keys using the given
3767	>	* reducer to combine values, or null if none
3768	>	* @since 1.8
3769		*/
3770	<	public boolean replace(K key, V oldValue, V newValue) {
3771	<	if (oldValue == null || newValue == null)
3770	>	public K reduceKeys(long parallelismThreshold,
3771	>	BiFunction<? super K, ? super K, ? extends K> reducer) {
3772	>	if (reducer == null) throw new NullPointerException();
3773	>	return new ReduceKeysTask<K,V>
3774	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3775	>	null, reducer).invoke();
3776	>	}
3777	>
3778	>	/**
3779	>	* Returns the result of accumulating the given transformation
3780	>	* of all keys using the given reducer to combine values, or
3781	>	* null if none.
3782	>	*
3783	>	* @param parallelismThreshold the (estimated) number of elements
3784	>	* needed for this operation to be executed in parallel
3785	>	* @param transformer a function returning the transformation
3786	>	* for an element, or null if there is no transformation (in
3787	>	* which case it is not combined)
3788	>	* @param reducer a commutative associative combining function
3789	>	* @param <U> the return type of the transformer
3790	>	* @return the result of accumulating the given transformation
3791	>	* of all keys
3792	>	* @since 1.8
3793	>	*/
3794	>	public <U> U reduceKeys(long parallelismThreshold,
3795	>	Function<? super K, ? extends U> transformer,
3796	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3797	>	if (transformer == null || reducer == null)
3798		throw new NullPointerException();
3799	<	int hash = hash(key);
3800	<	return segmentFor(hash).replace(key, hash, oldValue, newValue);
3799	>	return new MapReduceKeysTask<K,V,U>
3800	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3801	>	null, transformer, reducer).invoke();
3802		}
3803
3804		/**
3805	<	* Replace entry for key only if currently mapped to some value.
3806	<	* Acts as
3807	<	* <pre>
3808	<	*  if ((map.containsKey(key)) {
3809	<	*     return map.put(key, value);
3810	<	* } else return null;
3811	<	* </pre>
3812	<	* except that the action is performed atomically.
3813	<	* @param key key with which the specified value is associated.
3814	<	* @param value value to be associated with the specified key.
3815	<	* @return previous value associated with specified key, or <tt>null</tt>
3816	<	*         if there was no mapping for key.
3817	<	* @throws NullPointerException if the specified key or value is
968	<	*            <tt>null</tt>.
3805	>	* Returns the result of accumulating the given transformation
3806	>	* of all keys using the given reducer to combine values, and
3807	>	* the given basis as an identity value.
3808	>	*
3809	>	* @param parallelismThreshold the (estimated) number of elements
3810	>	* needed for this operation to be executed in parallel
3811	>	* @param transformer a function returning the transformation
3812	>	* for an element
3813	>	* @param basis the identity (initial default value) for the reduction
3814	>	* @param reducer a commutative associative combining function
3815	>	* @return the result of accumulating the given transformation
3816	>	* of all keys
3817	>	* @since 1.8
3818		*/
3819	<	public V replace(K key, V value) {
3820	<	if (value == null)
3819	>	public double reduceKeysToDouble(long parallelismThreshold,
3820	>	ToDoubleFunction<? super K> transformer,
3821	>	double basis,
3822	>	DoubleBinaryOperator reducer) {
3823	>	if (transformer == null || reducer == null)
3824		throw new NullPointerException();
3825	<	int hash = hash(key);
3826	<	return segmentFor(hash).replace(key, hash, value);
3825	>	return new MapReduceKeysToDoubleTask<K,V>
3826	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3827	>	null, transformer, basis, reducer).invoke();
3828		}
3829
3830	+	/**
3831	+	* Returns the result of accumulating the given transformation
3832	+	* of all keys using the given reducer to combine values, and
3833	+	* the given basis as an identity value.
3834	+	*
3835	+	* @param parallelismThreshold the (estimated) number of elements
3836	+	* needed for this operation to be executed in parallel
3837	+	* @param transformer a function returning the transformation
3838	+	* for an element
3839	+	* @param basis the identity (initial default value) for the reduction
3840	+	* @param reducer a commutative associative combining function
3841	+	* @return the result of accumulating the given transformation
3842	+	* of all keys
3843	+	* @since 1.8
3844	+	*/
3845	+	public long reduceKeysToLong(long parallelismThreshold,
3846	+	ToLongFunction<? super K> transformer,
3847	+	long basis,
3848	+	LongBinaryOperator reducer) {
3849	+	if (transformer == null || reducer == null)
3850	+	throw new NullPointerException();
3851	+	return new MapReduceKeysToLongTask<K,V>
3852	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3853	+	null, transformer, basis, reducer).invoke();
3854	+	}
3855
3856		/**
3857	<	* Removes all mappings from this map.
3857	>	* Returns the result of accumulating the given transformation
3858	>	* of all keys using the given reducer to combine values, and
3859	>	* the given basis as an identity value.
3860	>	*
3861	>	* @param parallelismThreshold the (estimated) number of elements
3862	>	* needed for this operation to be executed in parallel
3863	>	* @param transformer a function returning the transformation
3864	>	* for an element
3865	>	* @param basis the identity (initial default value) for the reduction
3866	>	* @param reducer a commutative associative combining function
3867	>	* @return the result of accumulating the given transformation
3868	>	* of all keys
3869	>	* @since 1.8
3870		*/
3871	<	public void clear() {
3872	<	for (int i = 0; i < segments.length; ++i)
3873	<	segments[i].clear();
3871	>	public int reduceKeysToInt(long parallelismThreshold,
3872	>	ToIntFunction<? super K> transformer,
3873	>	int basis,
3874	>	IntBinaryOperator reducer) {
3875	>	if (transformer == null || reducer == null)
3876	>	throw new NullPointerException();
3877	>	return new MapReduceKeysToIntTask<K,V>
3878	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3879	>	null, transformer, basis, reducer).invoke();
3880		}
3881
3882		/**
3883	<	* Returns a set view of the keys contained in this map.  The set is
988	<	* backed by the map, so changes to the map are reflected in the set, and
989	<	* vice-versa.  The set supports element removal, which removes the
990	<	* corresponding mapping from this map, via the <tt>Iterator.remove</tt>,
991	<	* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and
992	<	* <tt>clear</tt> operations.  It does not support the <tt>add</tt> or
993	<	* <tt>addAll</tt> operations.
994	<	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
995	<	* will never throw {@link java.util.ConcurrentModificationException},
996	<	* and guarantees to traverse elements as they existed upon
997	<	* construction of the iterator, and may (but is not guaranteed to)
998	<	* reflect any modifications subsequent to construction.
3883	>	* Performs the given action for each value.
3884		*
3885	<	* @return a set view of the keys contained in this map.
3885	>	* @param parallelismThreshold the (estimated) number of elements
3886	>	* needed for this operation to be executed in parallel
3887	>	* @param action the action
3888	>	* @since 1.8
3889		*/
3890	<	public Set<K> keySet() {
3891	<	Set<K> ks = keySet;
3892	<	return (ks != null) ? ks : (keySet = new KeySet());
3890	>	public void forEachValue(long parallelismThreshold,
3891	>	Consumer<? super V> action) {
3892	>	if (action == null)
3893	>	throw new NullPointerException();
3894	>	new ForEachValueTask<K,V>
3895	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3896	>	action).invoke();
3897		}
3898
3899	+	/**
3900	+	* Performs the given action for each non-null transformation
3901	+	* of each value.
3902	+	*
3903	+	* @param parallelismThreshold the (estimated) number of elements
3904	+	* needed for this operation to be executed in parallel
3905	+	* @param transformer a function returning the transformation
3906	+	* for an element, or null if there is no transformation (in
3907	+	* which case the action is not applied)
3908	+	* @param action the action
3909	+	* @param <U> the return type of the transformer
3910	+	* @since 1.8
3911	+	*/
3912	+	public <U> void forEachValue(long parallelismThreshold,
3913	+	Function<? super V, ? extends U> transformer,
3914	+	Consumer<? super U> action) {
3915	+	if (transformer == null || action == null)
3916	+	throw new NullPointerException();
3917	+	new ForEachTransformedValueTask<K,V,U>
3918	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3919	+	transformer, action).invoke();
3920	+	}
3921
3922		/**
3923	<	* Returns a collection view of the values contained in this map.  The
3924	<	* collection is backed by the map, so changes to the map are reflected in
3925	<	* the collection, and vice-versa.  The collection supports element
3926	<	* removal, which removes the corresponding mapping from this map, via the
3927	<	* <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.
3923	>	* Returns a non-null result from applying the given search
3924	>	* function on each value, or null if none.  Upon success,
3925	>	* further element processing is suppressed and the results of
3926	>	* any other parallel invocations of the search function are
3927	>	* ignored.
3928		*
3929	<	* @return a collection view of the values contained in this map.
3929	>	* @param parallelismThreshold the (estimated) number of elements
3930	>	* needed for this operation to be executed in parallel
3931	>	* @param searchFunction a function returning a non-null
3932	>	* result on success, else null
3933	>	* @param <U> the return type of the search function
3934	>	* @return a non-null result from applying the given search
3935	>	* function on each value, or null if none
3936	>	* @since 1.8
3937		*/
3938	<	public Collection<V> values() {
3939	<	Collection<V> vs = values;
3940	<	return (vs != null) ? vs : (values = new Values());
3938	>	public <U> U searchValues(long parallelismThreshold,
3939	>	Function<? super V, ? extends U> searchFunction) {
3940	>	if (searchFunction == null) throw new NullPointerException();
3941	>	return new SearchValuesTask<K,V,U>
3942	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3943	>	searchFunction, new AtomicReference<U>()).invoke();
3944		}
3945
3946	+	/**
3947	+	* Returns the result of accumulating all values using the
3948	+	* given reducer to combine values, or null if none.
3949	+	*
3950	+	* @param parallelismThreshold the (estimated) number of elements
3951	+	* needed for this operation to be executed in parallel
3952	+	* @param reducer a commutative associative combining function
3953	+	* @return the result of accumulating all values
3954	+	* @since 1.8
3955	+	*/
3956	+	public V reduceValues(long parallelismThreshold,
3957	+	BiFunction<? super V, ? super V, ? extends V> reducer) {
3958	+	if (reducer == null) throw new NullPointerException();
3959	+	return new ReduceValuesTask<K,V>
3960	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3961	+	null, reducer).invoke();
3962	+	}
3963
3964		/**
3965	<	* Returns a collection view of the mappings contained in this map.  Each
3966	<	* element in the returned collection is a <tt>Map.Entry</tt>.  The
3967	<	* 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.
3965	>	* Returns the result of accumulating the given transformation
3966	>	* of all values using the given reducer to combine values, or
3967	>	* null if none.
3968		*
3969	<	* @return a collection view of the mappings contained in this map.
3969	>	* @param parallelismThreshold the (estimated) number of elements
3970	>	* needed for this operation to be executed in parallel
3971	>	* @param transformer a function returning the transformation
3972	>	* for an element, or null if there is no transformation (in
3973	>	* which case it is not combined)
3974	>	* @param reducer a commutative associative combining function
3975	>	* @param <U> the return type of the transformer
3976	>	* @return the result of accumulating the given transformation
3977	>	* of all values
3978	>	* @since 1.8
3979		*/
3980	<	public Set<Map.Entry<K,V>> entrySet() {
3981	<	Set<Map.Entry<K,V>> es = entrySet;
3982	<	return (es != null) ? es : (entrySet = (Set<Map.Entry<K,V>>) (Set) new EntrySet());
3980	>	public <U> U reduceValues(long parallelismThreshold,
3981	>	Function<? super V, ? extends U> transformer,
3982	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3983	>	if (transformer == null || reducer == null)
3984	>	throw new NullPointerException();
3985	>	return new MapReduceValuesTask<K,V,U>
3986	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3987	>	null, transformer, reducer).invoke();
3988		}
3989
3990	+	/**
3991	+	* Returns the result of accumulating the given transformation
3992	+	* of all values using the given reducer to combine values,
3993	+	* and the given basis as an identity value.
3994	+	*
3995	+	* @param parallelismThreshold the (estimated) number of elements
3996	+	* needed for this operation to be executed in parallel
3997	+	* @param transformer a function returning the transformation
3998	+	* for an element
3999	+	* @param basis the identity (initial default value) for the reduction
4000	+	* @param reducer a commutative associative combining function
4001	+	* @return the result of accumulating the given transformation
4002	+	* of all values
4003	+	* @since 1.8
4004	+	*/
4005	+	public double reduceValuesToDouble(long parallelismThreshold,
4006	+	ToDoubleFunction<? super V> transformer,
4007	+	double basis,
4008	+	DoubleBinaryOperator reducer) {
4009	+	if (transformer == null || reducer == null)
4010	+	throw new NullPointerException();
4011	+	return new MapReduceValuesToDoubleTask<K,V>
4012	+	(null, batchFor(parallelismThreshold), 0, 0, table,
4013	+	null, transformer, basis, reducer).invoke();
4014	+	}
4015
4016		/**
4017	<	* Returns an enumeration of the keys in this table.
4017	>	* Returns the result of accumulating the given transformation
4018	>	* of all values using the given reducer to combine values,
4019	>	* and the given basis as an identity value.
4020		*
4021	<	* @return  an enumeration of the keys in this table.
4022	<	* @see     #keySet
4021	>	* @param parallelismThreshold the (estimated) number of elements
4022	>	* needed for this operation to be executed in parallel
4023	>	* @param transformer a function returning the transformation
4024	>	* for an element
4025	>	* @param basis the identity (initial default value) for the reduction
4026	>	* @param reducer a commutative associative combining function
4027	>	* @return the result of accumulating the given transformation
4028	>	* of all values
4029	>	* @since 1.8
4030		*/
4031	<	public Enumeration<K> keys() {
4032	<	return new KeyIterator();
4031	>	public long reduceValuesToLong(long parallelismThreshold,
4032	>	ToLongFunction<? super V> transformer,
4033	>	long basis,
4034	>	LongBinaryOperator reducer) {
4035	>	if (transformer == null || reducer == null)
4036	>	throw new NullPointerException();
4037	>	return new MapReduceValuesToLongTask<K,V>
4038	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4039	>	null, transformer, basis, reducer).invoke();
4040		}
4041
4042		/**
4043	<	* Returns an enumeration of the values in this table.
4043	>	* Returns the result of accumulating the given transformation
4044	>	* of all values using the given reducer to combine values,
4045	>	* and the given basis as an identity value.
4046		*
4047	<	* @return  an enumeration of the values in this table.
4048	<	* @see     #values
4047	>	* @param parallelismThreshold the (estimated) number of elements
4048	>	* needed for this operation to be executed in parallel
4049	>	* @param transformer a function returning the transformation
4050	>	* for an element
4051	>	* @param basis the identity (initial default value) for the reduction
4052	>	* @param reducer a commutative associative combining function
4053	>	* @return the result of accumulating the given transformation
4054	>	* of all values
4055	>	* @since 1.8
4056		*/
4057	<	public Enumeration<V> elements() {
4058	<	return new ValueIterator();
4057	>	public int reduceValuesToInt(long parallelismThreshold,
4058	>	ToIntFunction<? super V> transformer,
4059	>	int basis,
4060	>	IntBinaryOperator reducer) {
4061	>	if (transformer == null || reducer == null)
4062	>	throw new NullPointerException();
4063	>	return new MapReduceValuesToIntTask<K,V>
4064	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4065	>	null, transformer, basis, reducer).invoke();
4066		}
4067
4068	<	/* ---------------- Iterator Support -------------- */
4068	>	/**
4069	>	* Performs the given action for each entry.
4070	>	*
4071	>	* @param parallelismThreshold the (estimated) number of elements
4072	>	* needed for this operation to be executed in parallel
4073	>	* @param action the action
4074	>	* @since 1.8
4075	>	*/
4076	>	public void forEachEntry(long parallelismThreshold,
4077	>	Consumer<? super Map.Entry<K,V>> action) {
4078	>	if (action == null) throw new NullPointerException();
4079	>	new ForEachEntryTask<K,V>(null, batchFor(parallelismThreshold), 0, 0, table,
4080	>	action).invoke();
4081	>	}
4082
4083	<	abstract class HashIterator {
4084	<	int nextSegmentIndex;
4085	<	int nextTableIndex;
4086	<	HashEntry[] currentTable;
4087	<	HashEntry<K, V> nextEntry;
4088	<	HashEntry<K, V> lastReturned;
4083	>	/**
4084	>	* Performs the given action for each non-null transformation
4085	>	* of each entry.
4086	>	*
4087	>	* @param parallelismThreshold the (estimated) number of elements
4088	>	* needed for this operation to be executed in parallel
4089	>	* @param transformer a function returning the transformation
4090	>	* for an element, or null if there is no transformation (in
4091	>	* which case the action is not applied)
4092	>	* @param action the action
4093	>	* @param <U> the return type of the transformer
4094	>	* @since 1.8
4095	>	*/
4096	>	public <U> void forEachEntry(long parallelismThreshold,
4097	>	Function<Map.Entry<K,V>, ? extends U> transformer,
4098	>	Consumer<? super U> action) {
4099	>	if (transformer == null || action == null)
4100	>	throw new NullPointerException();
4101	>	new ForEachTransformedEntryTask<K,V,U>
4102	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4103	>	transformer, action).invoke();
4104	>	}
4105
4106	<	HashIterator() {
4107	<	nextSegmentIndex = segments.length - 1;
4108	<	nextTableIndex = -1;
4109	<	advance();
4110	<	}
4106	>	/**
4107	>	* Returns a non-null result from applying the given search
4108	>	* function on each entry, or null if none.  Upon success,
4109	>	* further element processing is suppressed and the results of
4110	>	* any other parallel invocations of the search function are
4111	>	* ignored.
4112	>	*
4113	>	* @param parallelismThreshold the (estimated) number of elements
4114	>	* needed for this operation to be executed in parallel
4115	>	* @param searchFunction a function returning a non-null
4116	>	* result on success, else null
4117	>	* @param <U> the return type of the search function
4118	>	* @return a non-null result from applying the given search
4119	>	* function on each entry, or null if none
4120	>	* @since 1.8
4121	>	*/
4122	>	public <U> U searchEntries(long parallelismThreshold,
4123	>	Function<Map.Entry<K,V>, ? extends U> searchFunction) {
4124	>	if (searchFunction == null) throw new NullPointerException();
4125	>	return new SearchEntriesTask<K,V,U>
4126	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4127	>	searchFunction, new AtomicReference<U>()).invoke();
4128	>	}
4129	>
4130	>	/**
4131	>	* Returns the result of accumulating all entries using the
4132	>	* given reducer to combine values, or null if none.
4133	>	*
4134	>	* @param parallelismThreshold the (estimated) number of elements
4135	>	* needed for this operation to be executed in parallel
4136	>	* @param reducer a commutative associative combining function
4137	>	* @return the result of accumulating all entries
4138	>	* @since 1.8
4139	>	*/
4140	>	public Map.Entry<K,V> reduceEntries(long parallelismThreshold,
4141	>	BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4142	>	if (reducer == null) throw new NullPointerException();
4143	>	return new ReduceEntriesTask<K,V>
4144	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4145	>	null, reducer).invoke();
4146	>	}
4147
4148	<	public boolean hasMoreElements() { return hasNext(); }
4148	>	/**
4149	>	* Returns the result of accumulating the given transformation
4150	>	* of all entries using the given reducer to combine values,
4151	>	* or null if none.
4152	>	*
4153	>	* @param parallelismThreshold the (estimated) number of elements
4154	>	* needed for this operation to be executed in parallel
4155	>	* @param transformer a function returning the transformation
4156	>	* for an element, or null if there is no transformation (in
4157	>	* which case it is not combined)
4158	>	* @param reducer a commutative associative combining function
4159	>	* @param <U> the return type of the transformer
4160	>	* @return the result of accumulating the given transformation
4161	>	* of all entries
4162	>	* @since 1.8
4163	>	*/
4164	>	public <U> U reduceEntries(long parallelismThreshold,
4165	>	Function<Map.Entry<K,V>, ? extends U> transformer,
4166	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
4167	>	if (transformer == null || reducer == null)
4168	>	throw new NullPointerException();
4169	>	return new MapReduceEntriesTask<K,V,U>
4170	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4171	>	null, transformer, reducer).invoke();
4172	>	}
4173
4174	<	final void advance() {
4175	<	if (nextEntry != null && (nextEntry = nextEntry.next) != null)
4176	<	return;
4174	>	/**
4175	>	* Returns the result of accumulating the given transformation
4176	>	* of all entries using the given reducer to combine values,
4177	>	* and the given basis as an identity value.
4178	>	*
4179	>	* @param parallelismThreshold the (estimated) number of elements
4180	>	* needed for this operation to be executed in parallel
4181	>	* @param transformer a function returning the transformation
4182	>	* for an element
4183	>	* @param basis the identity (initial default value) for the reduction
4184	>	* @param reducer a commutative associative combining function
4185	>	* @return the result of accumulating the given transformation
4186	>	* of all entries
4187	>	* @since 1.8
4188	>	*/
4189	>	public double reduceEntriesToDouble(long parallelismThreshold,
4190	>	ToDoubleFunction<Map.Entry<K,V>> transformer,
4191	>	double basis,
4192	>	DoubleBinaryOperator reducer) {
4193	>	if (transformer == null || reducer == null)
4194	>	throw new NullPointerException();
4195	>	return new MapReduceEntriesToDoubleTask<K,V>
4196	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4197	>	null, transformer, basis, reducer).invoke();
4198	>	}
4199
4200	<	while (nextTableIndex >= 0) {
4201	<	if ( (nextEntry = (HashEntry<K,V>)currentTable[nextTableIndex--]) != null)
4202	<	return;
4200	>	/**
4201	>	* Returns the result of accumulating the given transformation
4202	>	* of all entries using the given reducer to combine values,
4203	>	* and the given basis as an identity value.
4204	>	*
4205	>	* @param parallelismThreshold the (estimated) number of elements
4206	>	* needed for this operation to be executed in parallel
4207	>	* @param transformer a function returning the transformation
4208	>	* for an element
4209	>	* @param basis the identity (initial default value) for the reduction
4210	>	* @param reducer a commutative associative combining function
4211	>	* @return the result of accumulating the given transformation
4212	>	* of all entries
4213	>	* @since 1.8
4214	>	*/
4215	>	public long reduceEntriesToLong(long parallelismThreshold,
4216	>	ToLongFunction<Map.Entry<K,V>> transformer,
4217	>	long basis,
4218	>	LongBinaryOperator reducer) {
4219	>	if (transformer == null || reducer == null)
4220	>	throw new NullPointerException();
4221	>	return new MapReduceEntriesToLongTask<K,V>
4222	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4223	>	null, transformer, basis, reducer).invoke();
4224	>	}
4225	>
4226	>	/**
4227	>	* Returns the result of accumulating the given transformation
4228	>	* of all entries using the given reducer to combine values,
4229	>	* and the given basis as an identity value.
4230	>	*
4231	>	* @param parallelismThreshold the (estimated) number of elements
4232	>	* needed for this operation to be executed in parallel
4233	>	* @param transformer a function returning the transformation
4234	>	* for an element
4235	>	* @param basis the identity (initial default value) for the reduction
4236	>	* @param reducer a commutative associative combining function
4237	>	* @return the result of accumulating the given transformation
4238	>	* of all entries
4239	>	* @since 1.8
4240	>	*/
4241	>	public int reduceEntriesToInt(long parallelismThreshold,
4242	>	ToIntFunction<Map.Entry<K,V>> transformer,
4243	>	int basis,
4244	>	IntBinaryOperator reducer) {
4245	>	if (transformer == null || reducer == null)
4246	>	throw new NullPointerException();
4247	>	return new MapReduceEntriesToIntTask<K,V>
4248	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4249	>	null, transformer, basis, reducer).invoke();
4250	>	}
4251	>
4252	>
4253	>	/* ----------------Views -------------- */
4254	>
4255	>	/**
4256	>	* Base class for views.
4257	>	*/
4258	>	abstract static class CollectionView<K,V,E>
4259	>	implements Collection<E>, java.io.Serializable {
4260	>	private static final long serialVersionUID = 7249069246763182397L;
4261	>	final ConcurrentHashMap<K,V> map;
4262	>	CollectionView(ConcurrentHashMap<K,V> map)  { this.map = map; }
4263	>
4264	>	/**
4265	>	* Returns the map backing this view.
4266	>	*
4267	>	* @return the map backing this view
4268	>	*/
4269	>	public ConcurrentHashMap<K,V> getMap() { return map; }
4270	>
4271	>	/**
4272	>	* Removes all of the elements from this view, by removing all
4273	>	* the mappings from the map backing this view.
4274	>	*/
4275	>	public final void clear()      { map.clear(); }
4276	>	public final int size()        { return map.size(); }
4277	>	public final boolean isEmpty() { return map.isEmpty(); }
4278	>
4279	>	// implementations below rely on concrete classes supplying these
4280	>	// abstract methods
4281	>	/**
4282	>	* Returns a "weakly consistent" iterator that will never
4283	>	* throw {@link ConcurrentModificationException}, and
4284	>	* guarantees to traverse elements as they existed upon
4285	>	* construction of the iterator, and may (but is not
4286	>	* guaranteed to) reflect any modifications subsequent to
4287	>	* construction.
4288	>	*/
4289	>	public abstract Iterator<E> iterator();
4290	>	public abstract boolean contains(Object o);
4291	>	public abstract boolean remove(Object o);
4292	>
4293	>	private static final String oomeMsg = "Required array size too large";
4294	>
4295	>	public final Object[] toArray() {
4296	>	long sz = map.mappingCount();
4297	>	if (sz > MAX_ARRAY_SIZE)
4298	>	throw new OutOfMemoryError(oomeMsg);
4299	>	int n = (int)sz;
4300	>	Object[] r = new Object[n];
4301	>	int i = 0;
4302	>	for (E e : this) {
4303	>	if (i == n) {
4304	>	if (n >= MAX_ARRAY_SIZE)
4305	>	throw new OutOfMemoryError(oomeMsg);
4306	>	if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4307	>	n = MAX_ARRAY_SIZE;
4308	>	else
4309	>	n += (n >>> 1) + 1;
4310	>	r = Arrays.copyOf(r, n);
4311	>	}
4312	>	r[i++] = e;
4313		}
4314	+	return (i == n) ? r : Arrays.copyOf(r, i);
4315	+	}
4316
4317	<	while (nextSegmentIndex >= 0) {
4318	<	Segment<K,V> seg = (Segment<K,V>)segments[nextSegmentIndex--];
4319	<	if (seg.count != 0) {
4320	<	currentTable = seg.table;
4321	<	for (int j = currentTable.length - 1; j >= 0; --j) {
4322	<	if ( (nextEntry = (HashEntry<K,V>)currentTable[j]) != null) {
4323	<	nextTableIndex = j - 1;
4324	<	return;
4325	<	}
4326	<	}
4317	>	@SuppressWarnings("unchecked")
4318	>	public final <T> T[] toArray(T[] a) {
4319	>	long sz = map.mappingCount();
4320	>	if (sz > MAX_ARRAY_SIZE)
4321	>	throw new OutOfMemoryError(oomeMsg);
4322	>	int m = (int)sz;
4323	>	T[] r = (a.length >= m) ? a :
4324	>	(T[])java.lang.reflect.Array
4325	>	.newInstance(a.getClass().getComponentType(), m);
4326	>	int n = r.length;
4327	>	int i = 0;
4328	>	for (E e : this) {
4329	>	if (i == n) {
4330	>	if (n >= MAX_ARRAY_SIZE)
4331	>	throw new OutOfMemoryError(oomeMsg);
4332	>	if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4333	>	n = MAX_ARRAY_SIZE;
4334	>	else
4335	>	n += (n >>> 1) + 1;
4336	>	r = Arrays.copyOf(r, n);
4337		}
4338	+	r[i++] = (T)e;
4339	+	}
4340	+	if (a == r && i < n) {
4341	+	r[i] = null; // null-terminate
4342	+	return r;
4343		}
4344	+	return (i == n) ? r : Arrays.copyOf(r, i);
4345		}
4346
4347	<	public boolean hasNext() { return nextEntry != null; }
4347	>	/**
4348	>	* Returns a string representation of this collection.
4349	>	* The string representation consists of the string representations
4350	>	* of the collection's elements in the order they are returned by
4351	>	* its iterator, enclosed in square brackets ({@code "[]"}).
4352	>	* Adjacent elements are separated by the characters {@code ", "}
4353	>	* (comma and space).  Elements are converted to strings as by
4354	>	* {@link String#valueOf(Object)}.
4355	>	*
4356	>	* @return a string representation of this collection
4357	>	*/
4358	>	public final String toString() {
4359	>	StringBuilder sb = new StringBuilder();
4360	>	sb.append('[');
4361	>	Iterator<E> it = iterator();
4362	>	if (it.hasNext()) {
4363	>	for (;;) {
4364	>	Object e = it.next();
4365	>	sb.append(e == this ? "(this Collection)" : e);
4366	>	if (!it.hasNext())
4367	>	break;
4368	>	sb.append(',').append(' ');
4369	>	}
4370	>	}
4371	>	return sb.append(']').toString();
4372	>	}
4373
4374	<	HashEntry<K,V> nextEntry() {
4375	<	if (nextEntry == null)
4376	<	throw new NoSuchElementException();
4377	<	lastReturned = nextEntry;
4378	<	advance();
4379	<	return lastReturned;
4374	>	public final boolean containsAll(Collection<?> c) {
4375	>	if (c != this) {
4376	>	for (Object e : c) {
4377	>	if (e == null || !contains(e))
4378	>	return false;
4379	>	}
4380	>	}
4381	>	return true;
4382		}
4383
4384	<	public void remove() {
4385	<	if (lastReturned == null)
4386	<	throw new IllegalStateException();
4387	<	ConcurrentHashMap.this.remove(lastReturned.key);
4388	<	lastReturned = null;
4384	>	public final boolean removeAll(Collection<?> c) {
4385	>	boolean modified = false;
4386	>	for (Iterator<E> it = iterator(); it.hasNext();) {
4387	>	if (c.contains(it.next())) {
4388	>	it.remove();
4389	>	modified = true;
4390	>	}
4391	>	}
4392	>	return modified;
4393		}
1129	–	}
4394
4395	<	final class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> {
4396	<	public K next() { return super.nextEntry().key; }
4397	<	public K nextElement() { return super.nextEntry().key; }
4398	<	}
4395	>	public final boolean retainAll(Collection<?> c) {
4396	>	boolean modified = false;
4397	>	for (Iterator<E> it = iterator(); it.hasNext();) {
4398	>	if (!c.contains(it.next())) {
4399	>	it.remove();
4400	>	modified = true;
4401	>	}
4402	>	}
4403	>	return modified;
4404	>	}
4405
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; }
4406		}
4407
1141	–
1142	–
4408		/**
4409	<	* Entry iterator. Exported Entry objects must write-through
4410	<	* changes in setValue, even if the nodes have been cloned. So we
4411	<	* cannot return internal HashEntry objects. Instead, the iterator
4412	<	* itself acts as a forwarding pseudo-entry.
4409	>	* A view of a ConcurrentHashMap as a {@link Set} of keys, in
4410	>	* which additions may optionally be enabled by mapping to a
4411	>	* common value.  This class cannot be directly instantiated.
4412	>	* See {@link #keySet() keySet()},
4413	>	* {@link #keySet(Object) keySet(V)},
4414	>	* {@link #newKeySet() newKeySet()},
4415	>	* {@link #newKeySet(int) newKeySet(int)}.
4416	>	*
4417	>	* @since 1.8
4418		*/
4419	<	final class EntryIterator extends HashIterator implements Map.Entry<K,V>, Iterator<Entry<K,V>> {
4420	<	public Map.Entry<K,V> next() {
4421	<	nextEntry();
4422	<	return this;
4419	>	public static class KeySetView<K,V> extends CollectionView<K,V,K>
4420	>	implements Set<K>, java.io.Serializable {
4421	>	private static final long serialVersionUID = 7249069246763182397L;
4422	>	private final V value;
4423	>	KeySetView(ConcurrentHashMap<K,V> map, V value) {  // non-public
4424	>	super(map);
4425	>	this.value = value;
4426		}
4427
4428	<	public K getKey() {
4429	<	if (lastReturned == null)
4430	<	throw new IllegalStateException("Entry was removed");
4431	<	return lastReturned.key;
4432	<	}
4428	>	/**
4429	>	* Returns the default mapped value for additions,
4430	>	* or {@code null} if additions are not supported.
4431	>	*
4432	>	* @return the default mapped value for additions, or {@code null}
4433	>	* if not supported
4434	>	*/
4435	>	public V getMappedValue() { return value; }
4436
4437	<	public V getValue() {
4438	<	if (lastReturned == null)
4439	<	throw new IllegalStateException("Entry was removed");
4440	<	return ConcurrentHashMap.this.get(lastReturned.key);
4437	>	/**
4438	>	* {@inheritDoc}
4439	>	* @throws NullPointerException if the specified key is null
4440	>	*/
4441	>	public boolean contains(Object o) { return map.containsKey(o); }
4442	>
4443	>	/**
4444	>	* Removes the key from this map view, by removing the key (and its
4445	>	* corresponding value) from the backing map.  This method does
4446	>	* nothing if the key is not in the map.
4447	>	*
4448	>	* @param  o the key to be removed from the backing map
4449	>	* @return {@code true} if the backing map contained the specified key
4450	>	* @throws NullPointerException if the specified key is null
4451	>	*/
4452	>	public boolean remove(Object o) { return map.remove(o) != null; }
4453	>
4454	>	/**
4455	>	* @return an iterator over the keys of the backing map
4456	>	*/
4457	>	public Iterator<K> iterator() {
4458	>	Node<K,V>[] t;
4459	>	ConcurrentHashMap<K,V> m = map;
4460	>	int f = (t = m.table) == null ? 0 : t.length;
4461	>	return new KeyIterator<K,V>(t, f, 0, f, m);
4462		}
4463
4464	<	public V setValue(V value) {
4465	<	if (lastReturned == null)
4466	<	throw new IllegalStateException("Entry was removed");
4467	<	return ConcurrentHashMap.this.put(lastReturned.key, value);
4464	>	/**
4465	>	* Adds the specified key to this set view by mapping the key to
4466	>	* the default mapped value in the backing map, if defined.
4467	>	*
4468	>	* @param e key to be added
4469	>	* @return {@code true} if this set changed as a result of the call
4470	>	* @throws NullPointerException if the specified key is null
4471	>	* @throws UnsupportedOperationException if no default mapped value
4472	>	* for additions was provided
4473	>	*/
4474	>	public boolean add(K e) {
4475	>	V v;
4476	>	if ((v = value) == null)
4477	>	throw new UnsupportedOperationException();
4478	>	return map.putVal(e, v, true) == null;
4479		}
4480
4481	<	public boolean equals(Object o) {
4482	<	// If not acting as entry, just use default.
4483	<	if (lastReturned == null)
4484	<	return super.equals(o);
4485	<	if (!(o instanceof Map.Entry))
4486	<	return false;
4487	<	Map.Entry e = (Map.Entry)o;
4488	<	return eq(getKey(), e.getKey()) && eq(getValue(), e.getValue());
4481	>	/**
4482	>	* Adds all of the elements in the specified collection to this set,
4483	>	* as if by calling {@link #add} on each one.
4484	>	*
4485	>	* @param c the elements to be inserted into this set
4486	>	* @return {@code true} if this set changed as a result of the call
4487	>	* @throws NullPointerException if the collection or any of its
4488	>	* elements are {@code null}
4489	>	* @throws UnsupportedOperationException if no default mapped value
4490	>	* for additions was provided
4491	>	*/
4492	>	public boolean addAll(Collection<? extends K> c) {
4493	>	boolean added = false;
4494	>	V v;
4495	>	if ((v = value) == null)
4496	>	throw new UnsupportedOperationException();
4497	>	for (K e : c) {
4498	>	if (map.putVal(e, v, true) == null)
4499	>	added = true;
4500	>	}
4501	>	return added;
4502		}
4503
4504		public int hashCode() {
4505	<	// If not acting as entry, just use default.
4506	<	if (lastReturned == null)
4507	<	return super.hashCode();
4508	<
1188	<	Object k = getKey();
1189	<	Object v = getValue();
1190	<	return ((k == null) ? 0 : k.hashCode()) ^
1191	<	((v == null) ? 0 : v.hashCode());
4505	>	int h = 0;
4506	>	for (K e : this)
4507	>	h += e.hashCode();
4508	>	return h;
4509		}
4510
4511	<	public String toString() {
4512	<	// If not acting as entry, just use default.
4513	<	if (lastReturned == null)
4514	<	return super.toString();
4515	<	else
4516	<	return getKey() + "=" + getValue();
4511	>	public boolean equals(Object o) {
4512	>	Set<?> c;
4513	>	return ((o instanceof Set) &&
4514	>	((c = (Set<?>)o) == this ||
4515	>	(containsAll(c) && c.containsAll(this))));
4516	>	}
4517	>
4518	>	public Spliterator<K> spliterator() {
4519	>	Node<K,V>[] t;
4520	>	ConcurrentHashMap<K,V> m = map;
4521	>	long n = m.sumCount();
4522	>	int f = (t = m.table) == null ? 0 : t.length;
4523	>	return new KeySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4524	>	}
4525	>
4526	>	public void forEach(Consumer<? super K> action) {
4527	>	if (action == null) throw new NullPointerException();
4528	>	Node<K,V>[] t;
4529	>	if ((t = map.table) != null) {
4530	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4531	>	for (Node<K,V> p; (p = it.advance()) != null; )
4532	>	action.accept(p.key);
4533	>	}
4534		}
4535	+	}
4536
4537	<	boolean eq(Object o1, Object o2) {
4538	<	return (o1 == null ? o2 == null : o1.equals(o2));
4537	>	/**
4538	>	* A view of a ConcurrentHashMap as a {@link Collection} of
4539	>	* values, in which additions are disabled. This class cannot be
4540	>	* directly instantiated. See {@link #values()}.
4541	>	*/
4542	>	static final class ValuesView<K,V> extends CollectionView<K,V,V>
4543	>	implements Collection<V>, java.io.Serializable {
4544	>	private static final long serialVersionUID = 2249069246763182397L;
4545	>	ValuesView(ConcurrentHashMap<K,V> map) { super(map); }
4546	>	public final boolean contains(Object o) {
4547	>	return map.containsValue(o);
4548		}
4549
4550	<	}
4551	<
4552	<	final class KeySet extends AbstractSet<K> {
4553	<	public Iterator<K> iterator() {
4554	<	return new KeyIterator();
4550	>	public final boolean remove(Object o) {
4551	>	if (o != null) {
4552	>	for (Iterator<V> it = iterator(); it.hasNext();) {
4553	>	if (o.equals(it.next())) {
4554	>	it.remove();
4555	>	return true;
4556	>	}
4557	>	}
4558	>	}
4559	>	return false;
4560		}
4561	<	public int size() {
4562	<	return ConcurrentHashMap.this.size();
4561	>
4562	>	public final Iterator<V> iterator() {
4563	>	ConcurrentHashMap<K,V> m = map;
4564	>	Node<K,V>[] t;
4565	>	int f = (t = m.table) == null ? 0 : t.length;
4566	>	return new ValueIterator<K,V>(t, f, 0, f, m);
4567	>	}
4568	>
4569	>	public final boolean add(V e) {
4570	>	throw new UnsupportedOperationException();
4571	>	}
4572	>	public final boolean addAll(Collection<? extends V> c) {
4573	>	throw new UnsupportedOperationException();
4574	>	}
4575	>
4576	>	public Spliterator<V> spliterator() {
4577	>	Node<K,V>[] t;
4578	>	ConcurrentHashMap<K,V> m = map;
4579	>	long n = m.sumCount();
4580	>	int f = (t = m.table) == null ? 0 : t.length;
4581	>	return new ValueSpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4582	>	}
4583	>
4584	>	public void forEach(Consumer<? super V> action) {
4585	>	if (action == null) throw new NullPointerException();
4586	>	Node<K,V>[] t;
4587	>	if ((t = map.table) != null) {
4588	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4589	>	for (Node<K,V> p; (p = it.advance()) != null; )
4590	>	action.accept(p.val);
4591	>	}
4592		}
4593	+	}
4594	+
4595	+	/**
4596	+	* A view of a ConcurrentHashMap as a {@link Set} of (key, value)
4597	+	* entries.  This class cannot be directly instantiated. See
4598	+	* {@link #entrySet()}.
4599	+	*/
4600	+	static final class EntrySetView<K,V> extends CollectionView<K,V,Map.Entry<K,V>>
4601	+	implements Set<Map.Entry<K,V>>, java.io.Serializable {
4602	+	private static final long serialVersionUID = 2249069246763182397L;
4603	+	EntrySetView(ConcurrentHashMap<K,V> map) { super(map); }
4604	+
4605		public boolean contains(Object o) {
4606	<	return ConcurrentHashMap.this.containsKey(o);
4606	>	Object k, v, r; Map.Entry<?,?> e;
4607	>	return ((o instanceof Map.Entry) &&
4608	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4609	>	(r = map.get(k)) != null &&
4610	>	(v = e.getValue()) != null &&
4611	>	(v == r || v.equals(r)));
4612		}
4613	+
4614		public boolean remove(Object o) {
4615	<	return ConcurrentHashMap.this.remove(o) != null;
4615	>	Object k, v; Map.Entry<?,?> e;
4616	>	return ((o instanceof Map.Entry) &&
4617	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4618	>	(v = e.getValue()) != null &&
4619	>	map.remove(k, v));
4620	>	}
4621	>
4622	>	/**
4623	>	* @return an iterator over the entries of the backing map
4624	>	*/
4625	>	public Iterator<Map.Entry<K,V>> iterator() {
4626	>	ConcurrentHashMap<K,V> m = map;
4627	>	Node<K,V>[] t;
4628	>	int f = (t = m.table) == null ? 0 : t.length;
4629	>	return new EntryIterator<K,V>(t, f, 0, f, m);
4630		}
4631	<	public void clear() {
4632	<	ConcurrentHashMap.this.clear();
4631	>
4632	>	public boolean add(Entry<K,V> e) {
4633	>	return map.putVal(e.getKey(), e.getValue(), false) == null;
4634	>	}
4635	>
4636	>	public boolean addAll(Collection<? extends Entry<K,V>> c) {
4637	>	boolean added = false;
4638	>	for (Entry<K,V> e : c) {
4639	>	if (add(e))
4640	>	added = true;
4641	>	}
4642	>	return added;
4643		}
4644	<	public Object[] toArray() {
4645	<	Collection<K> c = new ArrayList<K>();
4646	<	for (Iterator<K> i = iterator(); i.hasNext(); )
4647	<	c.add(i.next());
4648	<	return c.toArray();
4644	>
4645	>	public final int hashCode() {
4646	>	int h = 0;
4647	>	Node<K,V>[] t;
4648	>	if ((t = map.table) != null) {
4649	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4650	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
4651	>	h += p.hashCode();
4652	>	}
4653	>	}
4654	>	return h;
4655		}
4656	<	public <T> T[] toArray(T[] a) {
4657	<	Collection<K> c = new ArrayList<K>();
4658	<	for (Iterator<K> i = iterator(); i.hasNext(); )
4659	<	c.add(i.next());
4660	<	return c.toArray(a);
4656	>
4657	>	public final boolean equals(Object o) {
4658	>	Set<?> c;
4659	>	return ((o instanceof Set) &&
4660	>	((c = (Set<?>)o) == this ||
4661	>	(containsAll(c) && c.containsAll(this))));
4662	>	}
4663	>
4664	>	public Spliterator<Map.Entry<K,V>> spliterator() {
4665	>	Node<K,V>[] t;
4666	>	ConcurrentHashMap<K,V> m = map;
4667	>	long n = m.sumCount();
4668	>	int f = (t = m.table) == null ? 0 : t.length;
4669	>	return new EntrySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n, m);
4670	>	}
4671	>
4672	>	public void forEach(Consumer<? super Map.Entry<K,V>> action) {
4673	>	if (action == null) throw new NullPointerException();
4674	>	Node<K,V>[] t;
4675	>	if ((t = map.table) != null) {
4676	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4677	>	for (Node<K,V> p; (p = it.advance()) != null; )
4678	>	action.accept(new MapEntry<K,V>(p.key, p.val, map));
4679	>	}
4680		}
4681	+
4682		}
4683
4684	<	final class Values extends AbstractCollection<V> {
4685	<	public Iterator<V> iterator() {
4686	<	return new ValueIterator();
4684	>	// -------------------------------------------------------
4685	>
4686	>	/**
4687	>	* Base class for bulk tasks. Repeats some fields and code from
4688	>	* class Traverser, because we need to subclass CountedCompleter.
4689	>	*/
4690	>	abstract static class BulkTask<K,V,R> extends CountedCompleter<R> {
4691	>	Node<K,V>[] tab;        // same as Traverser
4692	>	Node<K,V> next;
4693	>	int index;
4694	>	int baseIndex;
4695	>	int baseLimit;
4696	>	final int baseSize;
4697	>	int batch;              // split control
4698	>
4699	>	BulkTask(BulkTask<K,V,?> par, int b, int i, int f, Node<K,V>[] t) {
4700	>	super(par);
4701	>	this.batch = b;
4702	>	this.index = this.baseIndex = i;
4703	>	if ((this.tab = t) == null)
4704	>	this.baseSize = this.baseLimit = 0;
4705	>	else if (par == null)
4706	>	this.baseSize = this.baseLimit = t.length;
4707	>	else {
4708	>	this.baseLimit = f;
4709	>	this.baseSize = par.baseSize;
4710	>	}
4711		}
4712	<	public int size() {
4713	<	return ConcurrentHashMap.this.size();
4712	>
4713	>	/**
4714	>	* Same as Traverser version
4715	>	*/
4716	>	final Node<K,V> advance() {
4717	>	Node<K,V> e;
4718	>	if ((e = next) != null)
4719	>	e = e.next;
4720	>	for (;;) {
4721	>	Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
4722	>	if (e != null)
4723	>	return next = e;
4724	>	if (baseIndex >= baseLimit || (t = tab) == null ||
4725	>	(n = t.length) <= (i = index) || i < 0)
4726	>	return next = null;
4727	>	if ((e = tabAt(t, index)) != null && e.hash < 0) {
4728	>	if (e instanceof ForwardingNode) {
4729	>	tab = ((ForwardingNode<K,V>)e).nextTable;
4730	>	e = null;
4731	>	continue;
4732	>	}
4733	>	else if (e instanceof TreeBin)
4734	>	e = ((TreeBin<K,V>)e).first;
4735	>	else
4736	>	e = null;
4737	>	}
4738	>	if ((index += baseSize) >= n)
4739	>	index = ++baseIndex;    // visit upper slots if present
4740	>	}
4741		}
4742	<	public boolean contains(Object o) {
4743	<	return ConcurrentHashMap.this.containsValue(o);
4742	>	}
4743	>
4744	>	/*
4745	>	* Task classes. Coded in a regular but ugly format/style to
4746	>	* simplify checks that each variant differs in the right way from
4747	>	* others. The null screenings exist because compilers cannot tell
4748	>	* that we've already null-checked task arguments, so we force
4749	>	* simplest hoisted bypass to help avoid convoluted traps.
4750	>	*/
4751	>	@SuppressWarnings("serial")
4752	>	static final class ForEachKeyTask<K,V>
4753	>	extends BulkTask<K,V,Void> {
4754	>	final Consumer<? super K> action;
4755	>	ForEachKeyTask
4756	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4757	>	Consumer<? super K> action) {
4758	>	super(p, b, i, f, t);
4759	>	this.action = action;
4760	>	}
4761	>	public final void compute() {
4762	>	final Consumer<? super K> action;
4763	>	if ((action = this.action) != null) {
4764	>	for (int i = baseIndex, f, h; batch > 0 &&
4765	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4766	>	addToPendingCount(1);
4767	>	new ForEachKeyTask<K,V>
4768	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4769	>	action).fork();
4770	>	}
4771	>	for (Node<K,V> p; (p = advance()) != null;)
4772	>	action.accept(p.key);
4773	>	propagateCompletion();
4774	>	}
4775		}
4776	<	public void clear() {
4777	<	ConcurrentHashMap.this.clear();
4776	>	}
4777	>
4778	>	@SuppressWarnings("serial")
4779	>	static final class ForEachValueTask<K,V>
4780	>	extends BulkTask<K,V,Void> {
4781	>	final Consumer<? super V> action;
4782	>	ForEachValueTask
4783	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4784	>	Consumer<? super V> action) {
4785	>	super(p, b, i, f, t);
4786	>	this.action = action;
4787	>	}
4788	>	public final void compute() {
4789	>	final Consumer<? super V> action;
4790	>	if ((action = this.action) != null) {
4791	>	for (int i = baseIndex, f, h; batch > 0 &&
4792	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4793	>	addToPendingCount(1);
4794	>	new ForEachValueTask<K,V>
4795	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4796	>	action).fork();
4797	>	}
4798	>	for (Node<K,V> p; (p = advance()) != null;)
4799	>	action.accept(p.val);
4800	>	propagateCompletion();
4801	>	}
4802		}
4803	<	public Object[] toArray() {
4804	<	Collection<V> c = new ArrayList<V>();
4805	<	for (Iterator<V> i = iterator(); i.hasNext(); )
4806	<	c.add(i.next());
4807	<	return c.toArray();
4803	>	}
4804	>
4805	>	@SuppressWarnings("serial")
4806	>	static final class ForEachEntryTask<K,V>
4807	>	extends BulkTask<K,V,Void> {
4808	>	final Consumer<? super Entry<K,V>> action;
4809	>	ForEachEntryTask
4810	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4811	>	Consumer<? super Entry<K,V>> action) {
4812	>	super(p, b, i, f, t);
4813	>	this.action = action;
4814	>	}
4815	>	public final void compute() {
4816	>	final Consumer<? super Entry<K,V>> action;
4817	>	if ((action = this.action) != null) {
4818	>	for (int i = baseIndex, f, h; batch > 0 &&
4819	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4820	>	addToPendingCount(1);
4821	>	new ForEachEntryTask<K,V>
4822	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4823	>	action).fork();
4824	>	}
4825	>	for (Node<K,V> p; (p = advance()) != null; )
4826	>	action.accept(p);
4827	>	propagateCompletion();
4828	>	}
4829		}
4830	<	public <T> T[] toArray(T[] a) {
4831	<	Collection<V> c = new ArrayList<V>();
4832	<	for (Iterator<V> i = iterator(); i.hasNext(); )
4833	<	c.add(i.next());
4834	<	return c.toArray(a);
4830	>	}
4831	>
4832	>	@SuppressWarnings("serial")
4833	>	static final class ForEachMappingTask<K,V>
4834	>	extends BulkTask<K,V,Void> {
4835	>	final BiConsumer<? super K, ? super V> action;
4836	>	ForEachMappingTask
4837	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4838	>	BiConsumer<? super K,? super V> action) {
4839	>	super(p, b, i, f, t);
4840	>	this.action = action;
4841	>	}
4842	>	public final void compute() {
4843	>	final BiConsumer<? super K, ? super V> action;
4844	>	if ((action = this.action) != null) {
4845	>	for (int i = baseIndex, f, h; batch > 0 &&
4846	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4847	>	addToPendingCount(1);
4848	>	new ForEachMappingTask<K,V>
4849	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4850	>	action).fork();
4851	>	}
4852	>	for (Node<K,V> p; (p = advance()) != null; )
4853	>	action.accept(p.key, p.val);
4854	>	propagateCompletion();
4855	>	}
4856		}
4857		}
4858
4859	<	final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
4860	<	public Iterator<Map.Entry<K,V>> iterator() {
4861	<	return new EntryIterator();
4859	>	@SuppressWarnings("serial")
4860	>	static final class ForEachTransformedKeyTask<K,V,U>
4861	>	extends BulkTask<K,V,Void> {
4862	>	final Function<? super K, ? extends U> transformer;
4863	>	final Consumer<? super U> action;
4864	>	ForEachTransformedKeyTask
4865	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4866	>	Function<? super K, ? extends U> transformer, Consumer<? super U> action) {
4867	>	super(p, b, i, f, t);
4868	>	this.transformer = transformer; this.action = action;
4869	>	}
4870	>	public final void compute() {
4871	>	final Function<? super K, ? extends U> transformer;
4872	>	final Consumer<? super U> action;
4873	>	if ((transformer = this.transformer) != null &&
4874	>	(action = this.action) != null) {
4875	>	for (int i = baseIndex, f, h; batch > 0 &&
4876	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4877	>	addToPendingCount(1);
4878	>	new ForEachTransformedKeyTask<K,V,U>
4879	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4880	>	transformer, action).fork();
4881	>	}
4882	>	for (Node<K,V> p; (p = advance()) != null; ) {
4883	>	U u;
4884	>	if ((u = transformer.apply(p.key)) != null)
4885	>	action.accept(u);
4886	>	}
4887	>	propagateCompletion();
4888	>	}
4889		}
4890	<	public boolean contains(Object o) {
4891	<	if (!(o instanceof Map.Entry))
4892	<	return false;
4893	<	Map.Entry<K,V> e = (Map.Entry<K,V>)o;
4894	<	V v = ConcurrentHashMap.this.get(e.getKey());
4895	<	return v != null && v.equals(e.getValue());
4890	>	}
4891	>
4892	>	@SuppressWarnings("serial")
4893	>	static final class ForEachTransformedValueTask<K,V,U>
4894	>	extends BulkTask<K,V,Void> {
4895	>	final Function<? super V, ? extends U> transformer;
4896	>	final Consumer<? super U> action;
4897	>	ForEachTransformedValueTask
4898	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4899	>	Function<? super V, ? extends U> transformer, Consumer<? super U> action) {
4900	>	super(p, b, i, f, t);
4901	>	this.transformer = transformer; this.action = action;
4902	>	}
4903	>	public final void compute() {
4904	>	final Function<? super V, ? extends U> transformer;
4905	>	final Consumer<? super U> action;
4906	>	if ((transformer = this.transformer) != null &&
4907	>	(action = this.action) != null) {
4908	>	for (int i = baseIndex, f, h; batch > 0 &&
4909	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4910	>	addToPendingCount(1);
4911	>	new ForEachTransformedValueTask<K,V,U>
4912	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4913	>	transformer, action).fork();
4914	>	}
4915	>	for (Node<K,V> p; (p = advance()) != null; ) {
4916	>	U u;
4917	>	if ((u = transformer.apply(p.val)) != null)
4918	>	action.accept(u);
4919	>	}
4920	>	propagateCompletion();
4921	>	}
4922		}
4923	<	public boolean remove(Object o) {
4924	<	if (!(o instanceof Map.Entry))
4925	<	return false;
4926	<	Map.Entry<K,V> e = (Map.Entry<K,V>)o;
4927	<	return ConcurrentHashMap.this.remove(e.getKey(), e.getValue());
4923	>	}
4924	>
4925	>	@SuppressWarnings("serial")
4926	>	static final class ForEachTransformedEntryTask<K,V,U>
4927	>	extends BulkTask<K,V,Void> {
4928	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
4929	>	final Consumer<? super U> action;
4930	>	ForEachTransformedEntryTask
4931	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4932	>	Function<Map.Entry<K,V>, ? extends U> transformer, Consumer<? super U> action) {
4933	>	super(p, b, i, f, t);
4934	>	this.transformer = transformer; this.action = action;
4935	>	}
4936	>	public final void compute() {
4937	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
4938	>	final Consumer<? super U> action;
4939	>	if ((transformer = this.transformer) != null &&
4940	>	(action = this.action) != null) {
4941	>	for (int i = baseIndex, f, h; batch > 0 &&
4942	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4943	>	addToPendingCount(1);
4944	>	new ForEachTransformedEntryTask<K,V,U>
4945	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4946	>	transformer, action).fork();
4947	>	}
4948	>	for (Node<K,V> p; (p = advance()) != null; ) {
4949	>	U u;
4950	>	if ((u = transformer.apply(p)) != null)
4951	>	action.accept(u);
4952	>	}
4953	>	propagateCompletion();
4954	>	}
4955	>	}
4956	>	}
4957	>
4958	>	@SuppressWarnings("serial")
4959	>	static final class ForEachTransformedMappingTask<K,V,U>
4960	>	extends BulkTask<K,V,Void> {
4961	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
4962	>	final Consumer<? super U> action;
4963	>	ForEachTransformedMappingTask
4964	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4965	>	BiFunction<? super K, ? super V, ? extends U> transformer,
4966	>	Consumer<? super U> action) {
4967	>	super(p, b, i, f, t);
4968	>	this.transformer = transformer; this.action = action;
4969	>	}
4970	>	public final void compute() {
4971	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
4972	>	final Consumer<? super U> action;
4973	>	if ((transformer = this.transformer) != null &&
4974	>	(action = this.action) != null) {
4975	>	for (int i = baseIndex, f, h; batch > 0 &&
4976	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4977	>	addToPendingCount(1);
4978	>	new ForEachTransformedMappingTask<K,V,U>
4979	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4980	>	transformer, action).fork();
4981	>	}
4982	>	for (Node<K,V> p; (p = advance()) != null; ) {
4983	>	U u;
4984	>	if ((u = transformer.apply(p.key, p.val)) != null)
4985	>	action.accept(u);
4986	>	}
4987	>	propagateCompletion();
4988	>	}
4989	>	}
4990	>	}
4991	>
4992	>	@SuppressWarnings("serial")
4993	>	static final class SearchKeysTask<K,V,U>
4994	>	extends BulkTask<K,V,U> {
4995	>	final Function<? super K, ? extends U> searchFunction;
4996	>	final AtomicReference<U> result;
4997	>	SearchKeysTask
4998	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4999	>	Function<? super K, ? extends U> searchFunction,
5000	>	AtomicReference<U> result) {
5001	>	super(p, b, i, f, t);
5002	>	this.searchFunction = searchFunction; this.result = result;
5003	>	}
5004	>	public final U getRawResult() { return result.get(); }
5005	>	public final void compute() {
5006	>	final Function<? super K, ? extends U> searchFunction;
5007	>	final AtomicReference<U> result;
5008	>	if ((searchFunction = this.searchFunction) != null &&
5009	>	(result = this.result) != null) {
5010	>	for (int i = baseIndex, f, h; batch > 0 &&
5011	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5012	>	if (result.get() != null)
5013	>	return;
5014	>	addToPendingCount(1);
5015	>	new SearchKeysTask<K,V,U>
5016	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5017	>	searchFunction, result).fork();
5018	>	}
5019	>	while (result.get() == null) {
5020	>	U u;
5021	>	Node<K,V> p;
5022	>	if ((p = advance()) == null) {
5023	>	propagateCompletion();
5024	>	break;
5025	>	}
5026	>	if ((u = searchFunction.apply(p.key)) != null) {
5027	>	if (result.compareAndSet(null, u))
5028	>	quietlyCompleteRoot();
5029	>	break;
5030	>	}
5031	>	}
5032	>	}
5033		}
5034	<	public int size() {
5035	<	return ConcurrentHashMap.this.size();
5034	>	}
5035	>
5036	>	@SuppressWarnings("serial")
5037	>	static final class SearchValuesTask<K,V,U>
5038	>	extends BulkTask<K,V,U> {
5039	>	final Function<? super V, ? extends U> searchFunction;
5040	>	final AtomicReference<U> result;
5041	>	SearchValuesTask
5042	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5043	>	Function<? super V, ? extends U> searchFunction,
5044	>	AtomicReference<U> result) {
5045	>	super(p, b, i, f, t);
5046	>	this.searchFunction = searchFunction; this.result = result;
5047	>	}
5048	>	public final U getRawResult() { return result.get(); }
5049	>	public final void compute() {
5050	>	final Function<? super V, ? extends U> searchFunction;
5051	>	final AtomicReference<U> result;
5052	>	if ((searchFunction = this.searchFunction) != null &&
5053	>	(result = this.result) != null) {
5054	>	for (int i = baseIndex, f, h; batch > 0 &&
5055	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5056	>	if (result.get() != null)
5057	>	return;
5058	>	addToPendingCount(1);
5059	>	new SearchValuesTask<K,V,U>
5060	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5061	>	searchFunction, result).fork();
5062	>	}
5063	>	while (result.get() == null) {
5064	>	U u;
5065	>	Node<K,V> p;
5066	>	if ((p = advance()) == null) {
5067	>	propagateCompletion();
5068	>	break;
5069	>	}
5070	>	if ((u = searchFunction.apply(p.val)) != null) {
5071	>	if (result.compareAndSet(null, u))
5072	>	quietlyCompleteRoot();
5073	>	break;
5074	>	}
5075	>	}
5076	>	}
5077		}
5078	<	public void clear() {
5079	<	ConcurrentHashMap.this.clear();
5078	>	}
5079	>
5080	>	@SuppressWarnings("serial")
5081	>	static final class SearchEntriesTask<K,V,U>
5082	>	extends BulkTask<K,V,U> {
5083	>	final Function<Entry<K,V>, ? extends U> searchFunction;
5084	>	final AtomicReference<U> result;
5085	>	SearchEntriesTask
5086	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5087	>	Function<Entry<K,V>, ? extends U> searchFunction,
5088	>	AtomicReference<U> result) {
5089	>	super(p, b, i, f, t);
5090	>	this.searchFunction = searchFunction; this.result = result;
5091	>	}
5092	>	public final U getRawResult() { return result.get(); }
5093	>	public final void compute() {
5094	>	final Function<Entry<K,V>, ? extends U> searchFunction;
5095	>	final AtomicReference<U> result;
5096	>	if ((searchFunction = this.searchFunction) != null &&
5097	>	(result = this.result) != null) {
5098	>	for (int i = baseIndex, f, h; batch > 0 &&
5099	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5100	>	if (result.get() != null)
5101	>	return;
5102	>	addToPendingCount(1);
5103	>	new SearchEntriesTask<K,V,U>
5104	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5105	>	searchFunction, result).fork();
5106	>	}
5107	>	while (result.get() == null) {
5108	>	U u;
5109	>	Node<K,V> p;
5110	>	if ((p = advance()) == null) {
5111	>	propagateCompletion();
5112	>	break;
5113	>	}
5114	>	if ((u = searchFunction.apply(p)) != null) {
5115	>	if (result.compareAndSet(null, u))
5116	>	quietlyCompleteRoot();
5117	>	return;
5118	>	}
5119	>	}
5120	>	}
5121		}
5122	<	public Object[] toArray() {
5123	<	// Since we don't ordinarily have distinct Entry objects, we
5124	<	// must pack elements using exportable SimpleEntry
5125	<	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
5126	<	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
5127	<	c.add(new SimpleEntry<K,V>(i.next()));
5128	<	return c.toArray();
5122	>	}
5123	>
5124	>	@SuppressWarnings("serial")
5125	>	static final class SearchMappingsTask<K,V,U>
5126	>	extends BulkTask<K,V,U> {
5127	>	final BiFunction<? super K, ? super V, ? extends U> searchFunction;
5128	>	final AtomicReference<U> result;
5129	>	SearchMappingsTask
5130	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5131	>	BiFunction<? super K, ? super V, ? extends U> searchFunction,
5132	>	AtomicReference<U> result) {
5133	>	super(p, b, i, f, t);
5134	>	this.searchFunction = searchFunction; this.result = result;
5135	>	}
5136	>	public final U getRawResult() { return result.get(); }
5137	>	public final void compute() {
5138	>	final BiFunction<? super K, ? super V, ? extends U> searchFunction;
5139	>	final AtomicReference<U> result;
5140	>	if ((searchFunction = this.searchFunction) != null &&
5141	>	(result = this.result) != null) {
5142	>	for (int i = baseIndex, f, h; batch > 0 &&
5143	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5144	>	if (result.get() != null)
5145	>	return;
5146	>	addToPendingCount(1);
5147	>	new SearchMappingsTask<K,V,U>
5148	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5149	>	searchFunction, result).fork();
5150	>	}
5151	>	while (result.get() == null) {
5152	>	U u;
5153	>	Node<K,V> p;
5154	>	if ((p = advance()) == null) {
5155	>	propagateCompletion();
5156	>	break;
5157	>	}
5158	>	if ((u = searchFunction.apply(p.key, p.val)) != null) {
5159	>	if (result.compareAndSet(null, u))
5160	>	quietlyCompleteRoot();
5161	>	break;
5162	>	}
5163	>	}
5164	>	}
5165		}
5166	<	public <T> T[] toArray(T[] a) {
5167	<	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
5168	<	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
5169	<	c.add(new SimpleEntry<K,V>(i.next()));
5170	<	return c.toArray(a);
5166	>	}
5167	>
5168	>	@SuppressWarnings("serial")
5169	>	static final class ReduceKeysTask<K,V>
5170	>	extends BulkTask<K,V,K> {
5171	>	final BiFunction<? super K, ? super K, ? extends K> reducer;
5172	>	K result;
5173	>	ReduceKeysTask<K,V> rights, nextRight;
5174	>	ReduceKeysTask
5175	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5176	>	ReduceKeysTask<K,V> nextRight,
5177	>	BiFunction<? super K, ? super K, ? extends K> reducer) {
5178	>	super(p, b, i, f, t); this.nextRight = nextRight;
5179	>	this.reducer = reducer;
5180	>	}
5181	>	public final K getRawResult() { return result; }
5182	>	public final void compute() {
5183	>	final BiFunction<? super K, ? super K, ? extends K> reducer;
5184	>	if ((reducer = this.reducer) != null) {
5185	>	for (int i = baseIndex, f, h; batch > 0 &&
5186	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5187	>	addToPendingCount(1);
5188	>	(rights = new ReduceKeysTask<K,V>
5189	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5190	>	rights, reducer)).fork();
5191	>	}
5192	>	K r = null;
5193	>	for (Node<K,V> p; (p = advance()) != null; ) {
5194	>	K u = p.key;
5195	>	r = (r == null) ? u : u == null ? r : reducer.apply(r, u);
5196	>	}
5197	>	result = r;
5198	>	CountedCompleter<?> c;
5199	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5200	>	@SuppressWarnings("unchecked") ReduceKeysTask<K,V>
5201	>	t = (ReduceKeysTask<K,V>)c,
5202	>	s = t.rights;
5203	>	while (s != null) {
5204	>	K tr, sr;
5205	>	if ((sr = s.result) != null)
5206	>	t.result = (((tr = t.result) == null) ? sr :
5207	>	reducer.apply(tr, sr));
5208	>	s = t.rights = s.nextRight;
5209	>	}
5210	>	}
5211	>	}
5212		}
5213	+	}
5214
5215	+	@SuppressWarnings("serial")
5216	+	static final class ReduceValuesTask<K,V>
5217	+	extends BulkTask<K,V,V> {
5218	+	final BiFunction<? super V, ? super V, ? extends V> reducer;
5219	+	V result;
5220	+	ReduceValuesTask<K,V> rights, nextRight;
5221	+	ReduceValuesTask
5222	+	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5223	+	ReduceValuesTask<K,V> nextRight,
5224	+	BiFunction<? super V, ? super V, ? extends V> reducer) {
5225	+	super(p, b, i, f, t); this.nextRight = nextRight;
5226	+	this.reducer = reducer;
5227	+	}
5228	+	public final V getRawResult() { return result; }
5229	+	public final void compute() {
5230	+	final BiFunction<? super V, ? super V, ? extends V> reducer;
5231	+	if ((reducer = this.reducer) != null) {
5232	+	for (int i = baseIndex, f, h; batch > 0 &&
5233	+	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5234	+	addToPendingCount(1);
5235	+	(rights = new ReduceValuesTask<K,V>
5236	+	(this, batch >>>= 1, baseLimit = h, f, tab,
5237	+	rights, reducer)).fork();
5238	+	}
5239	+	V r = null;
5240	+	for (Node<K,V> p; (p = advance()) != null; ) {
5241	+	V v = p.val;
5242	+	r = (r == null) ? v : reducer.apply(r, v);
5243	+	}
5244	+	result = r;
5245	+	CountedCompleter<?> c;
5246	+	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5247	+	@SuppressWarnings("unchecked") ReduceValuesTask<K,V>
5248	+	t = (ReduceValuesTask<K,V>)c,
5249	+	s = t.rights;
5250	+	while (s != null) {
5251	+	V tr, sr;
5252	+	if ((sr = s.result) != null)
5253	+	t.result = (((tr = t.result) == null) ? sr :
5254	+	reducer.apply(tr, sr));
5255	+	s = t.rights = s.nextRight;
5256	+	}
5257	+	}
5258	+	}
5259	+	}
5260		}
5261
5262	<	/**
5263	<	* This duplicates java.util.AbstractMap.SimpleEntry until this class
5264	<	* is made accessible.
5265	<	*/
5266	<	static final class SimpleEntry<K,V> implements Entry<K,V> {
5267	<	K key;
5268	<	V value;
5262	>	@SuppressWarnings("serial")
5263	>	static final class ReduceEntriesTask<K,V>
5264	>	extends BulkTask<K,V,Map.Entry<K,V>> {
5265	>	final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5266	>	Map.Entry<K,V> result;
5267	>	ReduceEntriesTask<K,V> rights, nextRight;
5268	>	ReduceEntriesTask
5269	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5270	>	ReduceEntriesTask<K,V> nextRight,
5271	>	BiFunction<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5272	>	super(p, b, i, f, t); this.nextRight = nextRight;
5273	>	this.reducer = reducer;
5274	>	}
5275	>	public final Map.Entry<K,V> getRawResult() { return result; }
5276	>	public final void compute() {
5277	>	final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5278	>	if ((reducer = this.reducer) != null) {
5279	>	for (int i = baseIndex, f, h; batch > 0 &&
5280	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5281	>	addToPendingCount(1);
5282	>	(rights = new ReduceEntriesTask<K,V>
5283	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5284	>	rights, reducer)).fork();
5285	>	}
5286	>	Map.Entry<K,V> r = null;
5287	>	for (Node<K,V> p; (p = advance()) != null; )
5288	>	r = (r == null) ? p : reducer.apply(r, p);
5289	>	result = r;
5290	>	CountedCompleter<?> c;
5291	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5292	>	@SuppressWarnings("unchecked") ReduceEntriesTask<K,V>
5293	>	t = (ReduceEntriesTask<K,V>)c,
5294	>	s = t.rights;
5295	>	while (s != null) {
5296	>	Map.Entry<K,V> tr, sr;
5297	>	if ((sr = s.result) != null)
5298	>	t.result = (((tr = t.result) == null) ? sr :
5299	>	reducer.apply(tr, sr));
5300	>	s = t.rights = s.nextRight;
5301	>	}
5302	>	}
5303	>	}
5304	>	}
5305	>	}
5306
5307	<	public SimpleEntry(K key, V value) {
5308	<	this.key   = key;
5309	<	this.value = value;
5307	>	@SuppressWarnings("serial")
5308	>	static final class MapReduceKeysTask<K,V,U>
5309	>	extends BulkTask<K,V,U> {
5310	>	final Function<? super K, ? extends U> transformer;
5311	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5312	>	U result;
5313	>	MapReduceKeysTask<K,V,U> rights, nextRight;
5314	>	MapReduceKeysTask
5315	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5316	>	MapReduceKeysTask<K,V,U> nextRight,
5317	>	Function<? super K, ? extends U> transformer,
5318	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5319	>	super(p, b, i, f, t); this.nextRight = nextRight;
5320	>	this.transformer = transformer;
5321	>	this.reducer = reducer;
5322	>	}
5323	>	public final U getRawResult() { return result; }
5324	>	public final void compute() {
5325	>	final Function<? super K, ? extends U> transformer;
5326	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5327	>	if ((transformer = this.transformer) != null &&
5328	>	(reducer = this.reducer) != null) {
5329	>	for (int i = baseIndex, f, h; batch > 0 &&
5330	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5331	>	addToPendingCount(1);
5332	>	(rights = new MapReduceKeysTask<K,V,U>
5333	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5334	>	rights, transformer, reducer)).fork();
5335	>	}
5336	>	U r = null;
5337	>	for (Node<K,V> p; (p = advance()) != null; ) {
5338	>	U u;
5339	>	if ((u = transformer.apply(p.key)) != null)
5340	>	r = (r == null) ? u : reducer.apply(r, u);
5341	>	}
5342	>	result = r;
5343	>	CountedCompleter<?> c;
5344	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5345	>	@SuppressWarnings("unchecked") MapReduceKeysTask<K,V,U>
5346	>	t = (MapReduceKeysTask<K,V,U>)c,
5347	>	s = t.rights;
5348	>	while (s != null) {
5349	>	U tr, sr;
5350	>	if ((sr = s.result) != null)
5351	>	t.result = (((tr = t.result) == null) ? sr :
5352	>	reducer.apply(tr, sr));
5353	>	s = t.rights = s.nextRight;
5354	>	}
5355	>	}
5356	>	}
5357		}
5358	+	}
5359
5360	<	public SimpleEntry(Entry<K,V> e) {
5361	<	this.key   = e.getKey();
5362	<	this.value = e.getValue();
5360	>	@SuppressWarnings("serial")
5361	>	static final class MapReduceValuesTask<K,V,U>
5362	>	extends BulkTask<K,V,U> {
5363	>	final Function<? super V, ? extends U> transformer;
5364	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5365	>	U result;
5366	>	MapReduceValuesTask<K,V,U> rights, nextRight;
5367	>	MapReduceValuesTask
5368	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5369	>	MapReduceValuesTask<K,V,U> nextRight,
5370	>	Function<? super V, ? extends U> transformer,
5371	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5372	>	super(p, b, i, f, t); this.nextRight = nextRight;
5373	>	this.transformer = transformer;
5374	>	this.reducer = reducer;
5375	>	}
5376	>	public final U getRawResult() { return result; }
5377	>	public final void compute() {
5378	>	final Function<? super V, ? extends U> transformer;
5379	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5380	>	if ((transformer = this.transformer) != null &&
5381	>	(reducer = this.reducer) != null) {
5382	>	for (int i = baseIndex, f, h; batch > 0 &&
5383	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5384	>	addToPendingCount(1);
5385	>	(rights = new MapReduceValuesTask<K,V,U>
5386	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5387	>	rights, transformer, reducer)).fork();
5388	>	}
5389	>	U r = null;
5390	>	for (Node<K,V> p; (p = advance()) != null; ) {
5391	>	U u;
5392	>	if ((u = transformer.apply(p.val)) != null)
5393	>	r = (r == null) ? u : reducer.apply(r, u);
5394	>	}
5395	>	result = r;
5396	>	CountedCompleter<?> c;
5397	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5398	>	@SuppressWarnings("unchecked") MapReduceValuesTask<K,V,U>
5399	>	t = (MapReduceValuesTask<K,V,U>)c,
5400	>	s = t.rights;
5401	>	while (s != null) {
5402	>	U tr, sr;
5403	>	if ((sr = s.result) != null)
5404	>	t.result = (((tr = t.result) == null) ? sr :
5405	>	reducer.apply(tr, sr));
5406	>	s = t.rights = s.nextRight;
5407	>	}
5408	>	}
5409	>	}
5410		}
5411	+	}
5412
5413	<	public K getKey() {
5414	<	return key;
5413	>	@SuppressWarnings("serial")
5414	>	static final class MapReduceEntriesTask<K,V,U>
5415	>	extends BulkTask<K,V,U> {
5416	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5417	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5418	>	U result;
5419	>	MapReduceEntriesTask<K,V,U> rights, nextRight;
5420	>	MapReduceEntriesTask
5421	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5422	>	MapReduceEntriesTask<K,V,U> nextRight,
5423	>	Function<Map.Entry<K,V>, ? extends U> transformer,
5424	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5425	>	super(p, b, i, f, t); this.nextRight = nextRight;
5426	>	this.transformer = transformer;
5427	>	this.reducer = reducer;
5428	>	}
5429	>	public final U getRawResult() { return result; }
5430	>	public final void compute() {
5431	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5432	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5433	>	if ((transformer = this.transformer) != null &&
5434	>	(reducer = this.reducer) != null) {
5435	>	for (int i = baseIndex, f, h; batch > 0 &&
5436	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5437	>	addToPendingCount(1);
5438	>	(rights = new MapReduceEntriesTask<K,V,U>
5439	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5440	>	rights, transformer, reducer)).fork();
5441	>	}
5442	>	U r = null;
5443	>	for (Node<K,V> p; (p = advance()) != null; ) {
5444	>	U u;
5445	>	if ((u = transformer.apply(p)) != null)
5446	>	r = (r == null) ? u : reducer.apply(r, u);
5447	>	}
5448	>	result = r;
5449	>	CountedCompleter<?> c;
5450	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5451	>	@SuppressWarnings("unchecked") MapReduceEntriesTask<K,V,U>
5452	>	t = (MapReduceEntriesTask<K,V,U>)c,
5453	>	s = t.rights;
5454	>	while (s != null) {
5455	>	U tr, sr;
5456	>	if ((sr = s.result) != null)
5457	>	t.result = (((tr = t.result) == null) ? sr :
5458	>	reducer.apply(tr, sr));
5459	>	s = t.rights = s.nextRight;
5460	>	}
5461	>	}
5462	>	}
5463		}
5464	+	}
5465
5466	<	public V getValue() {
5467	<	return value;
5466	>	@SuppressWarnings("serial")
5467	>	static final class MapReduceMappingsTask<K,V,U>
5468	>	extends BulkTask<K,V,U> {
5469	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5470	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5471	>	U result;
5472	>	MapReduceMappingsTask<K,V,U> rights, nextRight;
5473	>	MapReduceMappingsTask
5474	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5475	>	MapReduceMappingsTask<K,V,U> nextRight,
5476	>	BiFunction<? super K, ? super V, ? extends U> transformer,
5477	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5478	>	super(p, b, i, f, t); this.nextRight = nextRight;
5479	>	this.transformer = transformer;
5480	>	this.reducer = reducer;
5481	>	}
5482	>	public final U getRawResult() { return result; }
5483	>	public final void compute() {
5484	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5485	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5486	>	if ((transformer = this.transformer) != null &&
5487	>	(reducer = this.reducer) != null) {
5488	>	for (int i = baseIndex, f, h; batch > 0 &&
5489	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5490	>	addToPendingCount(1);
5491	>	(rights = new MapReduceMappingsTask<K,V,U>
5492	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5493	>	rights, transformer, reducer)).fork();
5494	>	}
5495	>	U r = null;
5496	>	for (Node<K,V> p; (p = advance()) != null; ) {
5497	>	U u;
5498	>	if ((u = transformer.apply(p.key, p.val)) != null)
5499	>	r = (r == null) ? u : reducer.apply(r, u);
5500	>	}
5501	>	result = r;
5502	>	CountedCompleter<?> c;
5503	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5504	>	@SuppressWarnings("unchecked") MapReduceMappingsTask<K,V,U>
5505	>	t = (MapReduceMappingsTask<K,V,U>)c,
5506	>	s = t.rights;
5507	>	while (s != null) {
5508	>	U tr, sr;
5509	>	if ((sr = s.result) != null)
5510	>	t.result = (((tr = t.result) == null) ? sr :
5511	>	reducer.apply(tr, sr));
5512	>	s = t.rights = s.nextRight;
5513	>	}
5514	>	}
5515	>	}
5516		}
5517	+	}
5518
5519	<	public V setValue(V value) {
5520	<	V oldValue = this.value;
5521	<	this.value = value;
5522	<	return oldValue;
5519	>	@SuppressWarnings("serial")
5520	>	static final class MapReduceKeysToDoubleTask<K,V>
5521	>	extends BulkTask<K,V,Double> {
5522	>	final ToDoubleFunction<? super K> transformer;
5523	>	final DoubleBinaryOperator reducer;
5524	>	final double basis;
5525	>	double result;
5526	>	MapReduceKeysToDoubleTask<K,V> rights, nextRight;
5527	>	MapReduceKeysToDoubleTask
5528	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5529	>	MapReduceKeysToDoubleTask<K,V> nextRight,
5530	>	ToDoubleFunction<? super K> transformer,
5531	>	double basis,
5532	>	DoubleBinaryOperator reducer) {
5533	>	super(p, b, i, f, t); this.nextRight = nextRight;
5534	>	this.transformer = transformer;
5535	>	this.basis = basis; this.reducer = reducer;
5536	>	}
5537	>	public final Double getRawResult() { return result; }
5538	>	public final void compute() {
5539	>	final ToDoubleFunction<? super K> transformer;
5540	>	final DoubleBinaryOperator reducer;
5541	>	if ((transformer = this.transformer) != null &&
5542	>	(reducer = this.reducer) != null) {
5543	>	double r = this.basis;
5544	>	for (int i = baseIndex, f, h; batch > 0 &&
5545	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5546	>	addToPendingCount(1);
5547	>	(rights = new MapReduceKeysToDoubleTask<K,V>
5548	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5549	>	rights, transformer, r, reducer)).fork();
5550	>	}
5551	>	for (Node<K,V> p; (p = advance()) != null; )
5552	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key));
5553	>	result = r;
5554	>	CountedCompleter<?> c;
5555	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5556	>	@SuppressWarnings("unchecked") MapReduceKeysToDoubleTask<K,V>
5557	>	t = (MapReduceKeysToDoubleTask<K,V>)c,
5558	>	s = t.rights;
5559	>	while (s != null) {
5560	>	t.result = reducer.applyAsDouble(t.result, s.result);
5561	>	s = t.rights = s.nextRight;
5562	>	}
5563	>	}
5564	>	}
5565		}
5566	+	}
5567
5568	<	public boolean equals(Object o) {
5569	<	if (!(o instanceof Map.Entry))
5570	<	return false;
5571	<	Map.Entry e = (Map.Entry)o;
5572	<	return eq(key, e.getKey()) && eq(value, e.getValue());
5568	>	@SuppressWarnings("serial")
5569	>	static final class MapReduceValuesToDoubleTask<K,V>
5570	>	extends BulkTask<K,V,Double> {
5571	>	final ToDoubleFunction<? super V> transformer;
5572	>	final DoubleBinaryOperator reducer;
5573	>	final double basis;
5574	>	double result;
5575	>	MapReduceValuesToDoubleTask<K,V> rights, nextRight;
5576	>	MapReduceValuesToDoubleTask
5577	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5578	>	MapReduceValuesToDoubleTask<K,V> nextRight,
5579	>	ToDoubleFunction<? super V> transformer,
5580	>	double basis,
5581	>	DoubleBinaryOperator reducer) {
5582	>	super(p, b, i, f, t); this.nextRight = nextRight;
5583	>	this.transformer = transformer;
5584	>	this.basis = basis; this.reducer = reducer;
5585	>	}
5586	>	public final Double getRawResult() { return result; }
5587	>	public final void compute() {
5588	>	final ToDoubleFunction<? super V> transformer;
5589	>	final DoubleBinaryOperator reducer;
5590	>	if ((transformer = this.transformer) != null &&
5591	>	(reducer = this.reducer) != null) {
5592	>	double r = this.basis;
5593	>	for (int i = baseIndex, f, h; batch > 0 &&
5594	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5595	>	addToPendingCount(1);
5596	>	(rights = new MapReduceValuesToDoubleTask<K,V>
5597	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5598	>	rights, transformer, r, reducer)).fork();
5599	>	}
5600	>	for (Node<K,V> p; (p = advance()) != null; )
5601	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.val));
5602	>	result = r;
5603	>	CountedCompleter<?> c;
5604	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5605	>	@SuppressWarnings("unchecked") MapReduceValuesToDoubleTask<K,V>
5606	>	t = (MapReduceValuesToDoubleTask<K,V>)c,
5607	>	s = t.rights;
5608	>	while (s != null) {
5609	>	t.result = reducer.applyAsDouble(t.result, s.result);
5610	>	s = t.rights = s.nextRight;
5611	>	}
5612	>	}
5613	>	}
5614		}
5615	+	}
5616
5617	<	public int hashCode() {
5618	<	return ((key   == null)   ? 0 :   key.hashCode()) ^
5619	<	((value == null)   ? 0 : value.hashCode());
5617	>	@SuppressWarnings("serial")
5618	>	static final class MapReduceEntriesToDoubleTask<K,V>
5619	>	extends BulkTask<K,V,Double> {
5620	>	final ToDoubleFunction<Map.Entry<K,V>> transformer;
5621	>	final DoubleBinaryOperator reducer;
5622	>	final double basis;
5623	>	double result;
5624	>	MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
5625	>	MapReduceEntriesToDoubleTask
5626	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5627	>	MapReduceEntriesToDoubleTask<K,V> nextRight,
5628	>	ToDoubleFunction<Map.Entry<K,V>> transformer,
5629	>	double basis,
5630	>	DoubleBinaryOperator reducer) {
5631	>	super(p, b, i, f, t); this.nextRight = nextRight;
5632	>	this.transformer = transformer;
5633	>	this.basis = basis; this.reducer = reducer;
5634	>	}
5635	>	public final Double getRawResult() { return result; }
5636	>	public final void compute() {
5637	>	final ToDoubleFunction<Map.Entry<K,V>> transformer;
5638	>	final DoubleBinaryOperator reducer;
5639	>	if ((transformer = this.transformer) != null &&
5640	>	(reducer = this.reducer) != null) {
5641	>	double r = this.basis;
5642	>	for (int i = baseIndex, f, h; batch > 0 &&
5643	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5644	>	addToPendingCount(1);
5645	>	(rights = new MapReduceEntriesToDoubleTask<K,V>
5646	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5647	>	rights, transformer, r, reducer)).fork();
5648	>	}
5649	>	for (Node<K,V> p; (p = advance()) != null; )
5650	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p));
5651	>	result = r;
5652	>	CountedCompleter<?> c;
5653	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5654	>	@SuppressWarnings("unchecked") MapReduceEntriesToDoubleTask<K,V>
5655	>	t = (MapReduceEntriesToDoubleTask<K,V>)c,
5656	>	s = t.rights;
5657	>	while (s != null) {
5658	>	t.result = reducer.applyAsDouble(t.result, s.result);
5659	>	s = t.rights = s.nextRight;
5660	>	}
5661	>	}
5662	>	}
5663		}
5664	+	}
5665
5666	<	public String toString() {
5667	<	return key + "=" + value;
5666	>	@SuppressWarnings("serial")
5667	>	static final class MapReduceMappingsToDoubleTask<K,V>
5668	>	extends BulkTask<K,V,Double> {
5669	>	final ToDoubleBiFunction<? super K, ? super V> transformer;
5670	>	final DoubleBinaryOperator reducer;
5671	>	final double basis;
5672	>	double result;
5673	>	MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
5674	>	MapReduceMappingsToDoubleTask
5675	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5676	>	MapReduceMappingsToDoubleTask<K,V> nextRight,
5677	>	ToDoubleBiFunction<? super K, ? super V> transformer,
5678	>	double basis,
5679	>	DoubleBinaryOperator reducer) {
5680	>	super(p, b, i, f, t); this.nextRight = nextRight;
5681	>	this.transformer = transformer;
5682	>	this.basis = basis; this.reducer = reducer;
5683	>	}
5684	>	public final Double getRawResult() { return result; }
5685	>	public final void compute() {
5686	>	final ToDoubleBiFunction<? super K, ? super V> transformer;
5687	>	final DoubleBinaryOperator reducer;
5688	>	if ((transformer = this.transformer) != null &&
5689	>	(reducer = this.reducer) != null) {
5690	>	double r = this.basis;
5691	>	for (int i = baseIndex, f, h; batch > 0 &&
5692	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5693	>	addToPendingCount(1);
5694	>	(rights = new MapReduceMappingsToDoubleTask<K,V>
5695	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5696	>	rights, transformer, r, reducer)).fork();
5697	>	}
5698	>	for (Node<K,V> p; (p = advance()) != null; )
5699	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key, p.val));
5700	>	result = r;
5701	>	CountedCompleter<?> c;
5702	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5703	>	@SuppressWarnings("unchecked") MapReduceMappingsToDoubleTask<K,V>
5704	>	t = (MapReduceMappingsToDoubleTask<K,V>)c,
5705	>	s = t.rights;
5706	>	while (s != null) {
5707	>	t.result = reducer.applyAsDouble(t.result, s.result);
5708	>	s = t.rights = s.nextRight;
5709	>	}
5710	>	}
5711	>	}
5712		}
5713	+	}
5714
5715	<	static boolean eq(Object o1, Object o2) {
5716	<	return (o1 == null ? o2 == null : o1.equals(o2));
5715	>	@SuppressWarnings("serial")
5716	>	static final class MapReduceKeysToLongTask<K,V>
5717	>	extends BulkTask<K,V,Long> {
5718	>	final ToLongFunction<? super K> transformer;
5719	>	final LongBinaryOperator reducer;
5720	>	final long basis;
5721	>	long result;
5722	>	MapReduceKeysToLongTask<K,V> rights, nextRight;
5723	>	MapReduceKeysToLongTask
5724	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5725	>	MapReduceKeysToLongTask<K,V> nextRight,
5726	>	ToLongFunction<? super K> transformer,
5727	>	long basis,
5728	>	LongBinaryOperator reducer) {
5729	>	super(p, b, i, f, t); this.nextRight = nextRight;
5730	>	this.transformer = transformer;
5731	>	this.basis = basis; this.reducer = reducer;
5732	>	}
5733	>	public final Long getRawResult() { return result; }
5734	>	public final void compute() {
5735	>	final ToLongFunction<? super K> transformer;
5736	>	final LongBinaryOperator reducer;
5737	>	if ((transformer = this.transformer) != null &&
5738	>	(reducer = this.reducer) != null) {
5739	>	long r = this.basis;
5740	>	for (int i = baseIndex, f, h; batch > 0 &&
5741	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5742	>	addToPendingCount(1);
5743	>	(rights = new MapReduceKeysToLongTask<K,V>
5744	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5745	>	rights, transformer, r, reducer)).fork();
5746	>	}
5747	>	for (Node<K,V> p; (p = advance()) != null; )
5748	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.key));
5749	>	result = r;
5750	>	CountedCompleter<?> c;
5751	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5752	>	@SuppressWarnings("unchecked") MapReduceKeysToLongTask<K,V>
5753	>	t = (MapReduceKeysToLongTask<K,V>)c,
5754	>	s = t.rights;
5755	>	while (s != null) {
5756	>	t.result = reducer.applyAsLong(t.result, s.result);
5757	>	s = t.rights = s.nextRight;
5758	>	}
5759	>	}
5760	>	}
5761		}
5762		}
5763
5764	<	/* ---------------- Serialization Support -------------- */
5764	>	@SuppressWarnings("serial")
5765	>	static final class MapReduceValuesToLongTask<K,V>
5766	>	extends BulkTask<K,V,Long> {
5767	>	final ToLongFunction<? super V> transformer;
5768	>	final LongBinaryOperator reducer;
5769	>	final long basis;
5770	>	long result;
5771	>	MapReduceValuesToLongTask<K,V> rights, nextRight;
5772	>	MapReduceValuesToLongTask
5773	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5774	>	MapReduceValuesToLongTask<K,V> nextRight,
5775	>	ToLongFunction<? super V> transformer,
5776	>	long basis,
5777	>	LongBinaryOperator reducer) {
5778	>	super(p, b, i, f, t); this.nextRight = nextRight;
5779	>	this.transformer = transformer;
5780	>	this.basis = basis; this.reducer = reducer;
5781	>	}
5782	>	public final Long getRawResult() { return result; }
5783	>	public final void compute() {
5784	>	final ToLongFunction<? super V> transformer;
5785	>	final LongBinaryOperator reducer;
5786	>	if ((transformer = this.transformer) != null &&
5787	>	(reducer = this.reducer) != null) {
5788	>	long r = this.basis;
5789	>	for (int i = baseIndex, f, h; batch > 0 &&
5790	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5791	>	addToPendingCount(1);
5792	>	(rights = new MapReduceValuesToLongTask<K,V>
5793	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5794	>	rights, transformer, r, reducer)).fork();
5795	>	}
5796	>	for (Node<K,V> p; (p = advance()) != null; )
5797	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.val));
5798	>	result = r;
5799	>	CountedCompleter<?> c;
5800	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5801	>	@SuppressWarnings("unchecked") MapReduceValuesToLongTask<K,V>
5802	>	t = (MapReduceValuesToLongTask<K,V>)c,
5803	>	s = t.rights;
5804	>	while (s != null) {
5805	>	t.result = reducer.applyAsLong(t.result, s.result);
5806	>	s = t.rights = s.nextRight;
5807	>	}
5808	>	}
5809	>	}
5810	>	}
5811	>	}
5812
5813	<	/**
5814	<	* Save the state of the <tt>ConcurrentHashMap</tt>
5815	<	* instance to a stream (i.e.,
5816	<	* serialize it).
5817	<	* @param s the stream
5818	<	* @serialData
5819	<	* the key (Object) and value (Object)
5820	<	* for each key-value mapping, followed by a null pair.
5821	<	* The key-value mappings are emitted in no particular order.
5822	<	*/
5823	<	private void writeObject(java.io.ObjectOutputStream s) throws IOException  {
5824	<	s.defaultWriteObject();
5813	>	@SuppressWarnings("serial")
5814	>	static final class MapReduceEntriesToLongTask<K,V>
5815	>	extends BulkTask<K,V,Long> {
5816	>	final ToLongFunction<Map.Entry<K,V>> transformer;
5817	>	final LongBinaryOperator reducer;
5818	>	final long basis;
5819	>	long result;
5820	>	MapReduceEntriesToLongTask<K,V> rights, nextRight;
5821	>	MapReduceEntriesToLongTask
5822	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5823	>	MapReduceEntriesToLongTask<K,V> nextRight,
5824	>	ToLongFunction<Map.Entry<K,V>> transformer,
5825	>	long basis,
5826	>	LongBinaryOperator reducer) {
5827	>	super(p, b, i, f, t); this.nextRight = nextRight;
5828	>	this.transformer = transformer;
5829	>	this.basis = basis; this.reducer = reducer;
5830	>	}
5831	>	public final Long getRawResult() { return result; }
5832	>	public final void compute() {
5833	>	final ToLongFunction<Map.Entry<K,V>> transformer;
5834	>	final LongBinaryOperator reducer;
5835	>	if ((transformer = this.transformer) != null &&
5836	>	(reducer = this.reducer) != null) {
5837	>	long r = this.basis;
5838	>	for (int i = baseIndex, f, h; batch > 0 &&
5839	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5840	>	addToPendingCount(1);
5841	>	(rights = new MapReduceEntriesToLongTask<K,V>
5842	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5843	>	rights, transformer, r, reducer)).fork();
5844	>	}
5845	>	for (Node<K,V> p; (p = advance()) != null; )
5846	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p));
5847	>	result = r;
5848	>	CountedCompleter<?> c;
5849	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5850	>	@SuppressWarnings("unchecked") MapReduceEntriesToLongTask<K,V>
5851	>	t = (MapReduceEntriesToLongTask<K,V>)c,
5852	>	s = t.rights;
5853	>	while (s != null) {
5854	>	t.result = reducer.applyAsLong(t.result, s.result);
5855	>	s = t.rights = s.nextRight;
5856	>	}
5857	>	}
5858	>	}
5859	>	}
5860	>	}
5861
5862	<	for (int k = 0; k < segments.length; ++k) {
5863	<	Segment<K,V> seg = (Segment<K,V>)segments[k];
5864	<	seg.lock();
5865	<	try {
5866	<	HashEntry[] tab = seg.table;
5867	<	for (int i = 0; i < tab.length; ++i) {
5868	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i]; e != null; e = e.next) {
5869	<	s.writeObject(e.key);
5870	<	s.writeObject(e.value);
5862	>	@SuppressWarnings("serial")
5863	>	static final class MapReduceMappingsToLongTask<K,V>
5864	>	extends BulkTask<K,V,Long> {
5865	>	final ToLongBiFunction<? super K, ? super V> transformer;
5866	>	final LongBinaryOperator reducer;
5867	>	final long basis;
5868	>	long result;
5869	>	MapReduceMappingsToLongTask<K,V> rights, nextRight;
5870	>	MapReduceMappingsToLongTask
5871	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5872	>	MapReduceMappingsToLongTask<K,V> nextRight,
5873	>	ToLongBiFunction<? super K, ? super V> transformer,
5874	>	long basis,
5875	>	LongBinaryOperator reducer) {
5876	>	super(p, b, i, f, t); this.nextRight = nextRight;
5877	>	this.transformer = transformer;
5878	>	this.basis = basis; this.reducer = reducer;
5879	>	}
5880	>	public final Long getRawResult() { return result; }
5881	>	public final void compute() {
5882	>	final ToLongBiFunction<? super K, ? super V> transformer;
5883	>	final LongBinaryOperator reducer;
5884	>	if ((transformer = this.transformer) != null &&
5885	>	(reducer = this.reducer) != null) {
5886	>	long r = this.basis;
5887	>	for (int i = baseIndex, f, h; batch > 0 &&
5888	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5889	>	addToPendingCount(1);
5890	>	(rights = new MapReduceMappingsToLongTask<K,V>
5891	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5892	>	rights, transformer, r, reducer)).fork();
5893	>	}
5894	>	for (Node<K,V> p; (p = advance()) != null; )
5895	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.key, p.val));
5896	>	result = r;
5897	>	CountedCompleter<?> c;
5898	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5899	>	@SuppressWarnings("unchecked") MapReduceMappingsToLongTask<K,V>
5900	>	t = (MapReduceMappingsToLongTask<K,V>)c,
5901	>	s = t.rights;
5902	>	while (s != null) {
5903	>	t.result = reducer.applyAsLong(t.result, s.result);
5904	>	s = t.rights = s.nextRight;
5905		}
5906		}
1384	–	} finally {
1385	–	seg.unlock();
5907		}
5908		}
1388	–	s.writeObject(null);
1389	–	s.writeObject(null);
5909		}
5910
5911	<	/**
5912	<	* Reconstitute the <tt>ConcurrentHashMap</tt>
5913	<	* instance from a stream (i.e.,
5914	<	* deserialize it).
5915	<	* @param s the stream
5916	<	*/
5917	<	private void readObject(java.io.ObjectInputStream s)
5918	<	throws IOException, ClassNotFoundException  {
5919	<	s.defaultReadObject();
5911	>	@SuppressWarnings("serial")
5912	>	static final class MapReduceKeysToIntTask<K,V>
5913	>	extends BulkTask<K,V,Integer> {
5914	>	final ToIntFunction<? super K> transformer;
5915	>	final IntBinaryOperator reducer;
5916	>	final int basis;
5917	>	int result;
5918	>	MapReduceKeysToIntTask<K,V> rights, nextRight;
5919	>	MapReduceKeysToIntTask
5920	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5921	>	MapReduceKeysToIntTask<K,V> nextRight,
5922	>	ToIntFunction<? super K> transformer,
5923	>	int basis,
5924	>	IntBinaryOperator reducer) {
5925	>	super(p, b, i, f, t); this.nextRight = nextRight;
5926	>	this.transformer = transformer;
5927	>	this.basis = basis; this.reducer = reducer;
5928	>	}
5929	>	public final Integer getRawResult() { return result; }
5930	>	public final void compute() {
5931	>	final ToIntFunction<? super K> transformer;
5932	>	final IntBinaryOperator reducer;
5933	>	if ((transformer = this.transformer) != null &&
5934	>	(reducer = this.reducer) != null) {
5935	>	int r = this.basis;
5936	>	for (int i = baseIndex, f, h; batch > 0 &&
5937	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5938	>	addToPendingCount(1);
5939	>	(rights = new MapReduceKeysToIntTask<K,V>
5940	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5941	>	rights, transformer, r, reducer)).fork();
5942	>	}
5943	>	for (Node<K,V> p; (p = advance()) != null; )
5944	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.key));
5945	>	result = r;
5946	>	CountedCompleter<?> c;
5947	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5948	>	@SuppressWarnings("unchecked") MapReduceKeysToIntTask<K,V>
5949	>	t = (MapReduceKeysToIntTask<K,V>)c,
5950	>	s = t.rights;
5951	>	while (s != null) {
5952	>	t.result = reducer.applyAsInt(t.result, s.result);
5953	>	s = t.rights = s.nextRight;
5954	>	}
5955	>	}
5956	>	}
5957	>	}
5958	>	}
5959	>
5960	>	@SuppressWarnings("serial")
5961	>	static final class MapReduceValuesToIntTask<K,V>
5962	>	extends BulkTask<K,V,Integer> {
5963	>	final ToIntFunction<? super V> transformer;
5964	>	final IntBinaryOperator reducer;
5965	>	final int basis;
5966	>	int result;
5967	>	MapReduceValuesToIntTask<K,V> rights, nextRight;
5968	>	MapReduceValuesToIntTask
5969	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5970	>	MapReduceValuesToIntTask<K,V> nextRight,
5971	>	ToIntFunction<? super V> transformer,
5972	>	int basis,
5973	>	IntBinaryOperator reducer) {
5974	>	super(p, b, i, f, t); this.nextRight = nextRight;
5975	>	this.transformer = transformer;
5976	>	this.basis = basis; this.reducer = reducer;
5977	>	}
5978	>	public final Integer getRawResult() { return result; }
5979	>	public final void compute() {
5980	>	final ToIntFunction<? super V> transformer;
5981	>	final IntBinaryOperator reducer;
5982	>	if ((transformer = this.transformer) != null &&
5983	>	(reducer = this.reducer) != null) {
5984	>	int r = this.basis;
5985	>	for (int i = baseIndex, f, h; batch > 0 &&
5986	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5987	>	addToPendingCount(1);
5988	>	(rights = new MapReduceValuesToIntTask<K,V>
5989	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5990	>	rights, transformer, r, reducer)).fork();
5991	>	}
5992	>	for (Node<K,V> p; (p = advance()) != null; )
5993	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.val));
5994	>	result = r;
5995	>	CountedCompleter<?> c;
5996	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5997	>	@SuppressWarnings("unchecked") MapReduceValuesToIntTask<K,V>
5998	>	t = (MapReduceValuesToIntTask<K,V>)c,
5999	>	s = t.rights;
6000	>	while (s != null) {
6001	>	t.result = reducer.applyAsInt(t.result, s.result);
6002	>	s = t.rights = s.nextRight;
6003	>	}
6004	>	}
6005	>	}
6006	>	}
6007	>	}
6008
6009	<	// Initialize each segment to be minimally sized, and let grow.
6010	<	for (int i = 0; i < segments.length; ++i) {
6011	<	segments[i].setTable(new HashEntry[1]);
6009	>	@SuppressWarnings("serial")
6010	>	static final class MapReduceEntriesToIntTask<K,V>
6011	>	extends BulkTask<K,V,Integer> {
6012	>	final ToIntFunction<Map.Entry<K,V>> transformer;
6013	>	final IntBinaryOperator reducer;
6014	>	final int basis;
6015	>	int result;
6016	>	MapReduceEntriesToIntTask<K,V> rights, nextRight;
6017	>	MapReduceEntriesToIntTask
6018	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6019	>	MapReduceEntriesToIntTask<K,V> nextRight,
6020	>	ToIntFunction<Map.Entry<K,V>> transformer,
6021	>	int basis,
6022	>	IntBinaryOperator reducer) {
6023	>	super(p, b, i, f, t); this.nextRight = nextRight;
6024	>	this.transformer = transformer;
6025	>	this.basis = basis; this.reducer = reducer;
6026	>	}
6027	>	public final Integer getRawResult() { return result; }
6028	>	public final void compute() {
6029	>	final ToIntFunction<Map.Entry<K,V>> transformer;
6030	>	final IntBinaryOperator reducer;
6031	>	if ((transformer = this.transformer) != null &&
6032	>	(reducer = this.reducer) != null) {
6033	>	int r = this.basis;
6034	>	for (int i = baseIndex, f, h; batch > 0 &&
6035	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6036	>	addToPendingCount(1);
6037	>	(rights = new MapReduceEntriesToIntTask<K,V>
6038	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6039	>	rights, transformer, r, reducer)).fork();
6040	>	}
6041	>	for (Node<K,V> p; (p = advance()) != null; )
6042	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p));
6043	>	result = r;
6044	>	CountedCompleter<?> c;
6045	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6046	>	@SuppressWarnings("unchecked") MapReduceEntriesToIntTask<K,V>
6047	>	t = (MapReduceEntriesToIntTask<K,V>)c,
6048	>	s = t.rights;
6049	>	while (s != null) {
6050	>	t.result = reducer.applyAsInt(t.result, s.result);
6051	>	s = t.rights = s.nextRight;
6052	>	}
6053	>	}
6054	>	}
6055		}
6056	+	}
6057
6058	<	// Read the keys and values, and put the mappings in the table
6059	<	for (;;) {
6060	<	K key = (K) s.readObject();
6061	<	V value = (V) s.readObject();
6062	<	if (key == null)
6063	<	break;
6064	<	put(key, value);
6058	>	@SuppressWarnings("serial")
6059	>	static final class MapReduceMappingsToIntTask<K,V>
6060	>	extends BulkTask<K,V,Integer> {
6061	>	final ToIntBiFunction<? super K, ? super V> transformer;
6062	>	final IntBinaryOperator reducer;
6063	>	final int basis;
6064	>	int result;
6065	>	MapReduceMappingsToIntTask<K,V> rights, nextRight;
6066	>	MapReduceMappingsToIntTask
6067	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6068	>	MapReduceMappingsToIntTask<K,V> nextRight,
6069	>	ToIntBiFunction<? super K, ? super V> transformer,
6070	>	int basis,
6071	>	IntBinaryOperator reducer) {
6072	>	super(p, b, i, f, t); this.nextRight = nextRight;
6073	>	this.transformer = transformer;
6074	>	this.basis = basis; this.reducer = reducer;
6075	>	}
6076	>	public final Integer getRawResult() { return result; }
6077	>	public final void compute() {
6078	>	final ToIntBiFunction<? super K, ? super V> transformer;
6079	>	final IntBinaryOperator reducer;
6080	>	if ((transformer = this.transformer) != null &&
6081	>	(reducer = this.reducer) != null) {
6082	>	int r = this.basis;
6083	>	for (int i = baseIndex, f, h; batch > 0 &&
6084	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6085	>	addToPendingCount(1);
6086	>	(rights = new MapReduceMappingsToIntTask<K,V>
6087	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6088	>	rights, transformer, r, reducer)).fork();
6089	>	}
6090	>	for (Node<K,V> p; (p = advance()) != null; )
6091	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.key, p.val));
6092	>	result = r;
6093	>	CountedCompleter<?> c;
6094	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6095	>	@SuppressWarnings("unchecked") MapReduceMappingsToIntTask<K,V>
6096	>	t = (MapReduceMappingsToIntTask<K,V>)c,
6097	>	s = t.rights;
6098	>	while (s != null) {
6099	>	t.result = reducer.applyAsInt(t.result, s.result);
6100	>	s = t.rights = s.nextRight;
6101	>	}
6102	>	}
6103	>	}
6104		}
6105		}
1416	–	}
6106
6107	+	// Unsafe mechanics
6108	+	private static final sun.misc.Unsafe U;
6109	+	private static final long SIZECTL;
6110	+	private static final long TRANSFERINDEX;
6111	+	private static final long TRANSFERORIGIN;
6112	+	private static final long BASECOUNT;
6113	+	private static final long CELLSBUSY;
6114	+	private static final long CELLVALUE;
6115	+	private static final long ABASE;
6116	+	private static final int ASHIFT;
6117	+
6118	+	static {
6119	+	try {
6120	+	U = sun.misc.Unsafe.getUnsafe();
6121	+	Class<?> k = ConcurrentHashMap.class;
6122	+	SIZECTL = U.objectFieldOffset
6123	+	(k.getDeclaredField("sizeCtl"));
6124	+	TRANSFERINDEX = U.objectFieldOffset
6125	+	(k.getDeclaredField("transferIndex"));
6126	+	TRANSFERORIGIN = U.objectFieldOffset
6127	+	(k.getDeclaredField("transferOrigin"));
6128	+	BASECOUNT = U.objectFieldOffset
6129	+	(k.getDeclaredField("baseCount"));
6130	+	CELLSBUSY = U.objectFieldOffset
6131	+	(k.getDeclaredField("cellsBusy"));
6132	+	Class<?> ck = CounterCell.class;
6133	+	CELLVALUE = U.objectFieldOffset
6134	+	(ck.getDeclaredField("value"));
6135	+	Class<?> ak = Node[].class;
6136	+	ABASE = U.arrayBaseOffset(ak);
6137	+	int scale = U.arrayIndexScale(ak);
6138	+	if ((scale & (scale - 1)) != 0)
6139	+	throw new Error("data type scale not a power of two");
6140	+	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6141	+	} catch (Exception e) {
6142	+	throw new Error(e);
6143	+	}
6144	+	}
6145	+	}

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