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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 1.320 by jsr166, Sun Sep 8 01:11:03 2019 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.Enumeration;
17	>	import java.util.HashMap;
18	>	import java.util.Hashtable;
19	>	import java.util.Iterator;
20	>	import java.util.Map;
21	>	import java.util.NoSuchElementException;
22	>	import java.util.Set;
23	>	import java.util.Spliterator;
24	>	import java.util.concurrent.atomic.AtomicReference;
25	>	import java.util.concurrent.locks.LockSupport;
26	>	import java.util.concurrent.locks.ReentrantLock;
27	>	import java.util.function.BiConsumer;
28	>	import java.util.function.BiFunction;
29	>	import java.util.function.Consumer;
30	>	import java.util.function.DoubleBinaryOperator;
31	>	import java.util.function.Function;
32	>	import java.util.function.IntBinaryOperator;
33	>	import java.util.function.LongBinaryOperator;
34	>	import java.util.function.Predicate;
35	>	import java.util.function.ToDoubleBiFunction;
36	>	import java.util.function.ToDoubleFunction;
37	>	import java.util.function.ToIntBiFunction;
38	>	import java.util.function.ToIntFunction;
39	>	import java.util.function.ToLongBiFunction;
40	>	import java.util.function.ToLongFunction;
41	>	import java.util.stream.Stream;
42	>	import jdk.internal.misc.Unsafe;
43
44		/**
45		* A hash table supporting full concurrency of retrievals and
46	<	* adjustable expected concurrency for updates. This class obeys the
46	>	* high expected concurrency for updates. This class obeys the
47		* same functional specification as {@link java.util.Hashtable}, and
48		* includes versions of methods corresponding to each method of
49	<	* <tt>Hashtable</tt>. However, even though all operations are
49	>	* {@code Hashtable}. However, even though all operations are
50		* thread-safe, retrieval operations do <em>not</em> entail locking,
51		* and there is <em>not</em> any support for locking the entire table
52		* in a way that prevents all access.  This class is fully
53	<	* interoperable with <tt>Hashtable</tt> in programs that rely on its
53	>	* interoperable with {@code Hashtable} in programs that rely on its
54		* thread safety but not on its synchronization details.
55		*
56	<	* <p> Retrieval operations (including <tt>get</tt>) generally do not
57	<	* block, so may overlap with update operations (including
58	<	* <tt>put</tt> and <tt>remove</tt>). Retrievals reflect the results
59	<	* of the most recently <em>completed</em> update operations holding
60	<	* upon their onset.  For aggregate operations such as <tt>putAll</tt>
61	<	* and <tt>clear</tt>, concurrent retrievals may reflect insertion or
62	<	* removal of only some entries.  Similarly, Iterators and
63	<	* Enumerations return elements reflecting the state of the hash table
64	<	* at some point at or since the creation of the iterator/enumeration.
65	<	* They do <em>not</em> throw
66	<	* {@link ConcurrentModificationException}.  However, iterators are
67	<	* designed to be used by only one thread at a time.
68	<	*
69	<	* <p> The allowed concurrency among update operations is guided by
70	<	* the optional <tt>concurrencyLevel</tt> constructor argument
71	<	* (default 16), which is used as a hint for internal sizing.  The
72	<	* table is internally partitioned to try to permit the indicated
73	<	* number of concurrent updates without contention. Because placement
74	<	* in hash tables is essentially random, the actual concurrency will
75	<	* vary.  Ideally, you should choose a value to accommodate as many
76	<	* threads as will ever concurrently modify the table. Using a
77	<	* significantly higher value than you need can waste space and time,
78	<	* and a significantly lower value can lead to thread contention. But
79	<	* overestimates and underestimates within an order of magnitude do
80	<	* not usually have much noticeable impact. A value of one is
81	<	* appropriate when it is known that only one thread will modify and
82	<	* all others will only read. Also, resizing this or any other kind of
83	<	* hash table is a relatively slow operation, so, when possible, it is
84	<	* a good idea to provide estimates of expected table sizes in
85	<	* constructors.
56	>	* <p>Retrieval operations (including {@code get}) generally do not
57	>	* block, so may overlap with update operations (including {@code put}
58	>	* and {@code remove}). Retrievals reflect the results of the most
59	>	* recently <em>completed</em> update operations holding upon their
60	>	* onset. (More formally, an update operation for a given key bears a
61	>	* <em>happens-before</em> relation with any (non-null) retrieval for
62	>	* that key reporting the updated value.)  For aggregate operations
63	>	* such as {@code putAll} and {@code clear}, concurrent retrievals may
64	>	* reflect insertion or removal of only some entries.  Similarly,
65	>	* Iterators, Spliterators and Enumerations return elements reflecting the
66	>	* state of the hash table at some point at or since the creation of the
67	>	* iterator/enumeration.  They do <em>not</em> throw {@link
68	>	* java.util.ConcurrentModificationException ConcurrentModificationException}.
69	>	* However, iterators are designed to be used by only one thread at a time.
70	>	* Bear in mind that the results of aggregate status methods including
71	>	* {@code size}, {@code isEmpty}, and {@code containsValue} are typically
72	>	* useful only when a map is not undergoing concurrent updates in other threads.
73	>	* Otherwise the results of these methods reflect transient states
74	>	* that may be adequate for monitoring or estimation purposes, but not
75	>	* for program control.
76	>	*
77	>	* <p>The table is dynamically expanded when there are too many
78	>	* collisions (i.e., keys that have distinct hash codes but fall into
79	>	* the same slot modulo the table size), with the expected average
80	>	* effect of maintaining roughly two bins per mapping (corresponding
81	>	* to a 0.75 load factor threshold for resizing). There may be much
82	>	* variance around this average as mappings are added and removed, but
83	>	* overall, this maintains a commonly accepted time/space tradeoff for
84	>	* hash tables.  However, resizing this or any other kind of hash
85	>	* table may be a relatively slow operation. When possible, it is a
86	>	* good idea to provide a size estimate as an optional {@code
87	>	* initialCapacity} constructor argument. An additional optional
88	>	* {@code loadFactor} constructor argument provides a further means of
89	>	* customizing initial table capacity by specifying the table density
90	>	* to be used in calculating the amount of space to allocate for the
91	>	* given number of elements.  Also, for compatibility with previous
92	>	* versions of this class, constructors may optionally specify an
93	>	* expected {@code concurrencyLevel} as an additional hint for
94	>	* internal sizing.  Note that using many keys with exactly the same
95	>	* {@code hashCode()} is a sure way to slow down performance of any
96	>	* hash table. To ameliorate impact, when keys are {@link Comparable},
97	>	* this class may use comparison order among keys to help break ties.
98	>	*
99	>	* <p>A {@link Set} projection of a ConcurrentHashMap may be created
100	>	* (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed
101	>	* (using {@link #keySet(Object)} when only keys are of interest, and the
102	>	* mapped values are (perhaps transiently) not used or all take the
103	>	* same mapping value.
104	>	*
105	>	* <p>A ConcurrentHashMap can be used as a scalable frequency map (a
106	>	* form of histogram or multiset) by using {@link
107	>	* java.util.concurrent.atomic.LongAdder} values and initializing via
108	>	* {@link #computeIfAbsent computeIfAbsent}. For example, to add a count
109	>	* to a {@code ConcurrentHashMap<String,LongAdder> freqs}, you can use
110	>	* {@code freqs.computeIfAbsent(key, k -> new LongAdder()).increment();}
111		*
112		* <p>This class and its views and iterators implement all of the
113		* <em>optional</em> methods of the {@link Map} and {@link Iterator}
114		* interfaces.
115		*
116	<	* <p> Like {@link java.util.Hashtable} but unlike {@link
117	<	* java.util.HashMap}, this class does NOT allow <tt>null</tt> to be
118	<	* used as a key or value.
116	>	* <p>Like {@link Hashtable} but unlike {@link HashMap}, this class
117	>	* does <em>not</em> allow {@code null} to be used as a key or value.
118	>	*
119	>	* <p>ConcurrentHashMaps support a set of sequential and parallel bulk
120	>	* operations that, unlike most {@link Stream} methods, are designed
121	>	* to be safely, and often sensibly, applied even with maps that are
122	>	* being concurrently updated by other threads; for example, when
123	>	* computing a snapshot summary of the values in a shared registry.
124	>	* There are three kinds of operation, each with four forms, accepting
125	>	* functions with keys, values, entries, and (key, value) pairs as
126	>	* arguments and/or return values. Because the elements of a
127	>	* ConcurrentHashMap are not ordered in any particular way, and may be
128	>	* processed in different orders in different parallel executions, the
129	>	* correctness of supplied functions should not depend on any
130	>	* ordering, or on any other objects or values that may transiently
131	>	* change while computation is in progress; and except for forEach
132	>	* actions, should ideally be side-effect-free. Bulk operations on
133	>	* {@link Map.Entry} objects do not support method {@code setValue}.
134	>	*
135	>	* <ul>
136	>	* <li>forEach: Performs a given action on each element.
137	>	* A variant form applies a given transformation on each element
138	>	* before performing the action.
139	>	*
140	>	* <li>search: Returns the first available non-null result of
141	>	* applying a given function on each element; skipping further
142	>	* search when a result is found.
143	>	*
144	>	* <li>reduce: Accumulates each element.  The supplied reduction
145	>	* function cannot rely on ordering (more formally, it should be
146	>	* both associative and commutative).  There are five variants:
147	>	*
148	>	* <ul>
149	>	*
150	>	* <li>Plain reductions. (There is not a form of this method for
151	>	* (key, value) function arguments since there is no corresponding
152	>	* return type.)
153	>	*
154	>	* <li>Mapped reductions that accumulate the results of a given
155	>	* function applied to each element.
156	>	*
157	>	* <li>Reductions to scalar doubles, longs, and ints, using a
158	>	* given basis value.
159	>	*
160	>	* </ul>
161	>	* </ul>
162	>	*
163	>	* <p>These bulk operations accept a {@code parallelismThreshold}
164	>	* argument. Methods proceed sequentially if the current map size is
165	>	* estimated to be less than the given threshold. Using a value of
166	>	* {@code Long.MAX_VALUE} suppresses all parallelism.  Using a value
167	>	* of {@code 1} results in maximal parallelism by partitioning into
168	>	* enough subtasks to fully utilize the {@link
169	>	* ForkJoinPool#commonPool()} that is used for all parallel
170	>	* computations. Normally, you would initially choose one of these
171	>	* extreme values, and then measure performance of using in-between
172	>	* values that trade off overhead versus throughput.
173	>	*
174	>	* <p>The concurrency properties of bulk operations follow
175	>	* from those of ConcurrentHashMap: Any non-null result returned
176	>	* from {@code get(key)} and related access methods bears a
177	>	* happens-before relation with the associated insertion or
178	>	* update.  The result of any bulk operation reflects the
179	>	* composition of these per-element relations (but is not
180	>	* necessarily atomic with respect to the map as a whole unless it
181	>	* is somehow known to be quiescent).  Conversely, because keys
182	>	* and values in the map are never null, null serves as a reliable
183	>	* atomic indicator of the current lack of any result.  To
184	>	* maintain this property, null serves as an implicit basis for
185	>	* all non-scalar reduction operations. For the double, long, and
186	>	* int versions, the basis should be one that, when combined with
187	>	* any other value, returns that other value (more formally, it
188	>	* should be the identity element for the reduction). Most common
189	>	* reductions have these properties; for example, computing a sum
190	>	* with basis 0 or a minimum with basis MAX_VALUE.
191	>	*
192	>	* <p>Search and transformation functions provided as arguments
193	>	* should similarly return null to indicate the lack of any result
194	>	* (in which case it is not used). In the case of mapped
195	>	* reductions, this also enables transformations to serve as
196	>	* filters, returning null (or, in the case of primitive
197	>	* specializations, the identity basis) if the element should not
198	>	* be combined. You can create compound transformations and
199	>	* filterings by composing them yourself under this "null means
200	>	* there is nothing there now" rule before using them in search or
201	>	* reduce operations.
202	>	*
203	>	* <p>Methods accepting and/or returning Entry arguments maintain
204	>	* key-value associations. They may be useful for example when
205	>	* finding the key for the greatest value. Note that "plain" Entry
206	>	* arguments can be supplied using {@code new
207	>	* AbstractMap.SimpleEntry(k,v)}.
208	>	*
209	>	* <p>Bulk operations may complete abruptly, throwing an
210	>	* exception encountered in the application of a supplied
211	>	* function. Bear in mind when handling such exceptions that other
212	>	* concurrently executing functions could also have thrown
213	>	* exceptions, or would have done so if the first exception had
214	>	* not occurred.
215	>	*
216	>	* <p>Speedups for parallel compared to sequential forms are common
217	>	* but not guaranteed.  Parallel operations involving brief functions
218	>	* on small maps may execute more slowly than sequential forms if the
219	>	* underlying work to parallelize the computation is more expensive
220	>	* than the computation itself.  Similarly, parallelization may not
221	>	* lead to much actual parallelism if all processors are busy
222	>	* performing unrelated tasks.
223	>	*
224	>	* <p>All arguments to all task methods must be non-null.
225		*
226		* <p>This class is a member of the
227	<	* <a href="{@docRoot}/../guide/collections/index.html">
227	>	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
228		* Java Collections Framework</a>.
229		*
230		* @since 1.5
231		* @author Doug Lea
232		* @param <K> the type of keys maintained by this map
233	<	* @param <V> the type of mapped values
233	>	* @param <V> the type of mapped values
234		*/
235	<	public class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
236	<	implements ConcurrentMap<K, V>, Serializable {
235	>	public class ConcurrentHashMap<K,V> extends AbstractMap<K,V>
236	>	implements ConcurrentMap<K,V>, Serializable {
237		private static final long serialVersionUID = 7249069246763182397L;
238
239		/*
240	<	* The basic strategy is to subdivide the table among Segments,
241	<	* each of which itself is a concurrently readable hash table.
240	>	* Overview:
241	>	*
242	>	* The primary design goal of this hash table is to maintain
243	>	* concurrent readability (typically method get(), but also
244	>	* iterators and related methods) while minimizing update
245	>	* contention. Secondary goals are to keep space consumption about
246	>	* the same or better than java.util.HashMap, and to support high
247	>	* initial insertion rates on an empty table by many threads.
248	>	*
249	>	* This map usually acts as a binned (bucketed) hash table.  Each
250	>	* key-value mapping is held in a Node.  Most nodes are instances
251	>	* of the basic Node class with hash, key, value, and next
252	>	* fields. However, various subclasses exist: TreeNodes are
253	>	* arranged in balanced trees, not lists.  TreeBins hold the roots
254	>	* of sets of TreeNodes. ForwardingNodes are placed at the heads
255	>	* of bins during resizing. ReservationNodes are used as
256	>	* placeholders while establishing values in computeIfAbsent and
257	>	* related methods.  The types TreeBin, ForwardingNode, and
258	>	* ReservationNode do not hold normal user keys, values, or
259	>	* hashes, and are readily distinguishable during search etc
260	>	* because they have negative hash fields and null key and value
261	>	* fields. (These special nodes are either uncommon or transient,
262	>	* so the impact of carrying around some unused fields is
263	>	* insignificant.)
264	>	*
265	>	* The table is lazily initialized to a power-of-two size upon the
266	>	* first insertion.  Each bin in the table normally contains a
267	>	* list of Nodes (most often, the list has only zero or one Node).
268	>	* Table accesses require volatile/atomic reads, writes, and
269	>	* CASes.  Because there is no other way to arrange this without
270	>	* adding further indirections, we use intrinsics
271	>	* (jdk.internal.misc.Unsafe) operations.
272	>	*
273	>	* We use the top (sign) bit of Node hash fields for control
274	>	* purposes -- it is available anyway because of addressing
275	>	* constraints.  Nodes with negative hash fields are specially
276	>	* handled or ignored in map methods.
277	>	*
278	>	* Insertion (via put or its variants) of the first node in an
279	>	* empty bin is performed by just CASing it to the bin.  This is
280	>	* by far the most common case for put operations under most
281	>	* key/hash distributions.  Other update operations (insert,
282	>	* delete, and replace) require locks.  We do not want to waste
283	>	* the space required to associate a distinct lock object with
284	>	* each bin, so instead use the first node of a bin list itself as
285	>	* a lock. Locking support for these locks relies on builtin
286	>	* "synchronized" monitors.
287	>	*
288	>	* Using the first node of a list as a lock does not by itself
289	>	* suffice though: When a node is locked, any update must first
290	>	* validate that it is still the first node after locking it, and
291	>	* retry if not. Because new nodes are always appended to lists,
292	>	* once a node is first in a bin, it remains first until deleted
293	>	* or the bin becomes invalidated (upon resizing).
294	>	*
295	>	* The main disadvantage of per-bin locks is that other update
296	>	* operations on other nodes in a bin list protected by the same
297	>	* lock can stall, for example when user equals() or mapping
298	>	* functions take a long time.  However, statistically, under
299	>	* random hash codes, this is not a common problem.  Ideally, the
300	>	* frequency of nodes in bins follows a Poisson distribution
301	>	* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
302	>	* parameter of about 0.5 on average, given the resizing threshold
303	>	* of 0.75, although with a large variance because of resizing
304	>	* granularity. Ignoring variance, the expected occurrences of
305	>	* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
306	>	* first values are:
307	>	*
308	>	* 0:    0.60653066
309	>	* 1:    0.30326533
310	>	* 2:    0.07581633
311	>	* 3:    0.01263606
312	>	* 4:    0.00157952
313	>	* 5:    0.00015795
314	>	* 6:    0.00001316
315	>	* 7:    0.00000094
316	>	* 8:    0.00000006
317	>	* more: less than 1 in ten million
318	>	*
319	>	* Lock contention probability for two threads accessing distinct
320	>	* elements is roughly 1 / (8 * #elements) under random hashes.
321	>	*
322	>	* Actual hash code distributions encountered in practice
323	>	* sometimes deviate significantly from uniform randomness.  This
324	>	* includes the case when N > (1<<30), so some keys MUST collide.
325	>	* Similarly for dumb or hostile usages in which multiple keys are
326	>	* designed to have identical hash codes or ones that differs only
327	>	* in masked-out high bits. So we use a secondary strategy that
328	>	* applies when the number of nodes in a bin exceeds a
329	>	* threshold. These TreeBins use a balanced tree to hold nodes (a
330	>	* specialized form of red-black trees), bounding search time to
331	>	* O(log N).  Each search step in a TreeBin is at least twice as
332	>	* slow as in a regular list, but given that N cannot exceed
333	>	* (1<<64) (before running out of addresses) this bounds search
334	>	* steps, lock hold times, etc, to reasonable constants (roughly
335	>	* 100 nodes inspected per operation worst case) so long as keys
336	>	* are Comparable (which is very common -- String, Long, etc).
337	>	* TreeBin nodes (TreeNodes) also maintain the same "next"
338	>	* traversal pointers as regular nodes, so can be traversed in
339	>	* iterators in the same way.
340	>	*
341	>	* The table is resized when occupancy exceeds a percentage
342	>	* threshold (nominally, 0.75, but see below).  Any thread
343	>	* noticing an overfull bin may assist in resizing after the
344	>	* initiating thread allocates and sets up the replacement array.
345	>	* However, rather than stalling, these other threads may proceed
346	>	* with insertions etc.  The use of TreeBins shields us from the
347	>	* worst case effects of overfilling while resizes are in
348	>	* progress.  Resizing proceeds by transferring bins, one by one,
349	>	* from the table to the next table. However, threads claim small
350	>	* blocks of indices to transfer (via field transferIndex) before
351	>	* doing so, reducing contention.  A generation stamp in field
352	>	* sizeCtl ensures that resizings do not overlap. Because we are
353	>	* using power-of-two expansion, the elements from each bin must
354	>	* either stay at same index, or move with a power of two
355	>	* offset. We eliminate unnecessary node creation by catching
356	>	* cases where old nodes can be reused because their next fields
357	>	* won't change.  On average, only about one-sixth of them need
358	>	* cloning when a table doubles. The nodes they replace will be
359	>	* garbage collectible as soon as they are no longer referenced by
360	>	* any reader thread that may be in the midst of concurrently
361	>	* traversing table.  Upon transfer, the old table bin contains
362	>	* only a special forwarding node (with hash field "MOVED") that
363	>	* contains the next table as its key. On encountering a
364	>	* forwarding node, access and update operations restart, using
365	>	* the new table.
366	>	*
367	>	* Each bin transfer requires its bin lock, which can stall
368	>	* waiting for locks while resizing. However, because other
369	>	* threads can join in and help resize rather than contend for
370	>	* locks, average aggregate waits become shorter as resizing
371	>	* progresses.  The transfer operation must also ensure that all
372	>	* accessible bins in both the old and new table are usable by any
373	>	* traversal.  This is arranged in part by proceeding from the
374	>	* last bin (table.length - 1) up towards the first.  Upon seeing
375	>	* a forwarding node, traversals (see class Traverser) arrange to
376	>	* move to the new table without revisiting nodes.  To ensure that
377	>	* no intervening nodes are skipped even when moved out of order,
378	>	* a stack (see class TableStack) is created on first encounter of
379	>	* a forwarding node during a traversal, to maintain its place if
380	>	* later processing the current table. The need for these
381	>	* save/restore mechanics is relatively rare, but when one
382	>	* forwarding node is encountered, typically many more will be.
383	>	* So Traversers use a simple caching scheme to avoid creating so
384	>	* many new TableStack nodes. (Thanks to Peter Levart for
385	>	* suggesting use of a stack here.)
386	>	*
387	>	* The traversal scheme also applies to partial traversals of
388	>	* ranges of bins (via an alternate Traverser constructor)
389	>	* to support partitioned aggregate operations.  Also, read-only
390	>	* operations give up if ever forwarded to a null table, which
391	>	* provides support for shutdown-style clearing, which is also not
392	>	* currently implemented.
393	>	*
394	>	* Lazy table initialization minimizes footprint until first use,
395	>	* and also avoids resizings when the first operation is from a
396	>	* putAll, constructor with map argument, or deserialization.
397	>	* These cases attempt to override the initial capacity settings,
398	>	* but harmlessly fail to take effect in cases of races.
399	>	*
400	>	* The element count is maintained using a specialization of
401	>	* LongAdder. We need to incorporate a specialization rather than
402	>	* just use a LongAdder in order to access implicit
403	>	* contention-sensing that leads to creation of multiple
404	>	* CounterCells.  The counter mechanics avoid contention on
405	>	* updates but can encounter cache thrashing if read too
406	>	* frequently during concurrent access. To avoid reading so often,
407	>	* resizing under contention is attempted only upon adding to a
408	>	* bin already holding two or more nodes. Under uniform hash
409	>	* distributions, the probability of this occurring at threshold
410	>	* is around 13%, meaning that only about 1 in 8 puts check
411	>	* threshold (and after resizing, many fewer do so).
412	>	*
413	>	* TreeBins use a special form of comparison for search and
414	>	* related operations (which is the main reason we cannot use
415	>	* existing collections such as TreeMaps). TreeBins contain
416	>	* Comparable elements, but may contain others, as well as
417	>	* elements that are Comparable but not necessarily Comparable for
418	>	* the same T, so we cannot invoke compareTo among them. To handle
419	>	* this, the tree is ordered primarily by hash value, then by
420	>	* Comparable.compareTo order if applicable.  On lookup at a node,
421	>	* if elements are not comparable or compare as 0 then both left
422	>	* and right children may need to be searched in the case of tied
423	>	* hash values. (This corresponds to the full list search that
424	>	* would be necessary if all elements were non-Comparable and had
425	>	* tied hashes.) On insertion, to keep a total ordering (or as
426	>	* close as is required here) across rebalancings, we compare
427	>	* classes and identityHashCodes as tie-breakers. The red-black
428	>	* balancing code is updated from pre-jdk-collections
429	>	* (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
430	>	* based in turn on Cormen, Leiserson, and Rivest "Introduction to
431	>	* Algorithms" (CLR).
432	>	*
433	>	* TreeBins also require an additional locking mechanism.  While
434	>	* list traversal is always possible by readers even during
435	>	* updates, tree traversal is not, mainly because of tree-rotations
436	>	* that may change the root node and/or its linkages.  TreeBins
437	>	* include a simple read-write lock mechanism parasitic on the
438	>	* main bin-synchronization strategy: Structural adjustments
439	>	* associated with an insertion or removal are already bin-locked
440	>	* (and so cannot conflict with other writers) but must wait for
441	>	* ongoing readers to finish. Since there can be only one such
442	>	* waiter, we use a simple scheme using a single "waiter" field to
443	>	* block writers.  However, readers need never block.  If the root
444	>	* lock is held, they proceed along the slow traversal path (via
445	>	* next-pointers) until the lock becomes available or the list is
446	>	* exhausted, whichever comes first. These cases are not fast, but
447	>	* maximize aggregate expected throughput.
448	>	*
449	>	* Maintaining API and serialization compatibility with previous
450	>	* versions of this class introduces several oddities. Mainly: We
451	>	* leave untouched but unused constructor arguments referring to
452	>	* concurrencyLevel. We accept a loadFactor constructor argument,
453	>	* but apply it only to initial table capacity (which is the only
454	>	* time that we can guarantee to honor it.) We also declare an
455	>	* unused "Segment" class that is instantiated in minimal form
456	>	* only when serializing.
457	>	*
458	>	* Also, solely for compatibility with previous versions of this
459	>	* class, it extends AbstractMap, even though all of its methods
460	>	* are overridden, so it is just useless baggage.
461	>	*
462	>	* This file is organized to make things a little easier to follow
463	>	* while reading than they might otherwise: First the main static
464	>	* declarations and utilities, then fields, then main public
465	>	* methods (with a few factorings of multiple public methods into
466	>	* internal ones), then sizing methods, trees, traversers, and
467	>	* bulk operations.
468		*/
469
470		/* ---------------- Constants -------------- */
471
472		/**
473	<	* The default initial number of table slots for this table.
474	<	* Used when not otherwise specified in constructor.
473	>	* The largest possible table capacity.  This value must be
474	>	* exactly 1<<30 to stay within Java array allocation and indexing
475	>	* bounds for power of two table sizes, and is further required
476	>	* because the top two bits of 32bit hash fields are used for
477	>	* control purposes.
478		*/
479	<	static int DEFAULT_INITIAL_CAPACITY = 16;
479	>	private static final int MAXIMUM_CAPACITY = 1 << 30;
480
481		/**
482	<	* The maximum capacity, used if a higher value is implicitly
483	<	* 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.
482	>	* The default initial table capacity.  Must be a power of 2
483	>	* (i.e., at least 1) and at most MAXIMUM_CAPACITY.
484		*/
485	<	static final int MAXIMUM_CAPACITY = 1 << 30;
485	>	private static final int DEFAULT_CAPACITY = 16;
486
487		/**
488	<	* The default load factor for this table.  Used when not
489	<	* otherwise specified in constructor.
488	>	* The largest possible (non-power of two) array size.
489	>	* Needed by toArray and related methods.
490		*/
491	<	static final float DEFAULT_LOAD_FACTOR = 0.75f;
491	>	static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
492
493		/**
494	<	* The default number of concurrency control segments.
495	<	**/
496	<	static final int DEFAULT_SEGMENTS = 16;
494	>	* The default concurrency level for this table. Unused but
495	>	* defined for compatibility with previous versions of this class.
496	>	*/
497	>	private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
498
499		/**
500	<	* The maximum number of segments to allow; used to bound
501	<	* constructor arguments.
500	>	* The load factor for this table. Overrides of this value in
501	>	* constructors affect only the initial table capacity.  The
502	>	* actual floating point value isn't normally used -- it is
503	>	* simpler to use expressions such as {@code n - (n >>> 2)} for
504	>	* the associated resizing threshold.
505		*/
506	<	static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
506	>	private static final float LOAD_FACTOR = 0.75f;
507
508		/**
509	<	* Number of unsynchronized retries in size and containsValue
510	<	* methods before resorting to locking. This is used to avoid
511	<	* unbounded retries if tables undergo continuous modification
512	<	* which would make it impossible to obtain an accurate result.
509	>	* The bin count threshold for using a tree rather than list for a
510	>	* bin.  Bins are converted to trees when adding an element to a
511	>	* bin with at least this many nodes. The value must be greater
512	>	* than 2, and should be at least 8 to mesh with assumptions in
513	>	* tree removal about conversion back to plain bins upon
514	>	* shrinkage.
515		*/
516	<	static final int RETRIES_BEFORE_LOCK = 2;
124	<
125	<	/* ---------------- Fields -------------- */
516	>	static final int TREEIFY_THRESHOLD = 8;
517
518		/**
519	<	* Mask value for indexing into segments. The upper bits of a
520	<	* key's hash code are used to choose the segment.
521	<	**/
522	<	final int segmentMask;
519	>	* The bin count threshold for untreeifying a (split) bin during a
520	>	* resize operation. Should be less than TREEIFY_THRESHOLD, and at
521	>	* most 6 to mesh with shrinkage detection under removal.
522	>	*/
523	>	static final int UNTREEIFY_THRESHOLD = 6;
524
525		/**
526	<	* Shift value for indexing within segments.
527	<	**/
528	<	final int segmentShift;
526	>	* The smallest table capacity for which bins may be treeified.
527	>	* (Otherwise the table is resized if too many nodes in a bin.)
528	>	* The value should be at least 4 * TREEIFY_THRESHOLD to avoid
529	>	* conflicts between resizing and treeification thresholds.
530	>	*/
531	>	static final int MIN_TREEIFY_CAPACITY = 64;
532
533		/**
534	<	* The segments, each of which is a specialized hash table
534	>	* Minimum number of rebinnings per transfer step. Ranges are
535	>	* subdivided to allow multiple resizer threads.  This value
536	>	* serves as a lower bound to avoid resizers encountering
537	>	* excessive memory contention.  The value should be at least
538	>	* DEFAULT_CAPACITY.
539		*/
540	<	final Segment[] segments;
540	>	private static final int MIN_TRANSFER_STRIDE = 16;
541
542	<	transient Set<K> keySet;
543	<	transient Set<Map.Entry<K,V>> entrySet;
544	<	transient Collection<V> values;
542	>	/**
543	>	* The number of bits used for generation stamp in sizeCtl.
544	>	* Must be at least 6 for 32bit arrays.
545	>	*/
546	>	private static final int RESIZE_STAMP_BITS = 16;
547
548	<	/* ---------------- Small Utilities -------------- */
548	>	/**
549	>	* The maximum number of threads that can help resize.
550	>	* Must fit in 32 - RESIZE_STAMP_BITS bits.
551	>	*/
552	>	private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1;
553
554		/**
555	<	* Returns a hash code for non-null Object x.
151	<	* Uses the same hash code spreader as most other java.util hash tables.
152	<	* @param x the object serving as a key
153	<	* @return the hash code
555	>	* The bit shift for recording size stamp in sizeCtl.
556		*/
557	<	static int hash(Object x) {
558	<	int h = x.hashCode();
559	<	h += ~(h << 9);
560	<	h ^=  (h >>> 14);
561	<	h +=  (h << 4);
562	<	h ^=  (h >>> 10);
563	<	return h;
564	<	}
557	>	private static final int RESIZE_STAMP_SHIFT = 32 - RESIZE_STAMP_BITS;
558	>
559	>	/*
560	>	* Encodings for Node hash fields. See above for explanation.
561	>	*/
562	>	static final int MOVED     = -1; // hash for forwarding nodes
563	>	static final int TREEBIN   = -2; // hash for roots of trees
564	>	static final int RESERVED  = -3; // hash for transient reservations
565	>	static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
566	>
567	>	/** Number of CPUS, to place bounds on some sizings */
568	>	static final int NCPU = Runtime.getRuntime().availableProcessors();
569
570		/**
571	<	* Returns the segment that should be used for key with given hash
572	<	* @param hash the hash code for the key
573	<	* @return the segment
571	>	* Serialized pseudo-fields, provided only for jdk7 compatibility.
572	>	* @serialField segments Segment[]
573	>	*   The segments, each of which is a specialized hash table.
574	>	* @serialField segmentMask int
575	>	*   Mask value for indexing into segments. The upper bits of a
576	>	*   key's hash code are used to choose the segment.
577	>	* @serialField segmentShift int
578	>	*   Shift value for indexing within segments.
579		*/
580	<	final Segment<K,V> segmentFor(int hash) {
581	<	return (Segment<K,V>) segments[(hash >>> segmentShift) & segmentMask];
582	<	}
580	>	private static final ObjectStreamField[] serialPersistentFields = {
581	>	new ObjectStreamField("segments", Segment[].class),
582	>	new ObjectStreamField("segmentMask", Integer.TYPE),
583	>	new ObjectStreamField("segmentShift", Integer.TYPE),
584	>	};
585
586	<	/* ---------------- Inner Classes -------------- */
586	>	/* ---------------- Nodes -------------- */
587
588		/**
589	<	* ConcurrentHashMap list entry. Note that this is never exported
590	<	* out as a user-visible Map.Entry.
591	<	*
592	<	* Because the value field is volatile, not final, it is legal wrt
593	<	* the Java Memory Model for an unsynchronized reader to see null
594	<	* 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.
589	>	* Key-value entry.  This class is never exported out as a
590	>	* user-mutable Map.Entry (i.e., one supporting setValue; see
591	>	* MapEntry below), but can be used for read-only traversals used
592	>	* in bulk tasks.  Subclasses of Node with a negative hash field
593	>	* are special, and contain null keys and values (but are never
594	>	* exported).  Otherwise, keys and vals are never null.
595		*/
596	<	static final class HashEntry<K,V> {
188	<	final K key;
596	>	static class Node<K,V> implements Map.Entry<K,V> {
597		final int hash;
598	<	volatile V value;
599	<	final HashEntry<K,V> next;
598	>	final K key;
599	>	volatile V val;
600	>	volatile Node<K,V> next;
601
602	<	HashEntry(K key, int hash, HashEntry<K,V> next, V value) {
194	<	this.key = key;
602	>	Node(int hash, K key, V val) {
603		this.hash = hash;
604	+	this.key = key;
605	+	this.val = val;
606	+	}
607	+
608	+	Node(int hash, K key, V val, Node<K,V> next) {
609	+	this(hash, key, val);
610		this.next = next;
611	<	this.value = value;
611	>	}
612	>
613	>	public final K getKey()     { return key; }
614	>	public final V getValue()   { return val; }
615	>	public final int hashCode() { return key.hashCode() ^ val.hashCode(); }
616	>	public final String toString() {
617	>	return Helpers.mapEntryToString(key, val);
618	>	}
619	>	public final V setValue(V value) {
620	>	throw new UnsupportedOperationException();
621	>	}
622	>
623	>	public final boolean equals(Object o) {
624	>	Object k, v, u; Map.Entry<?,?> e;
625	>	return ((o instanceof Map.Entry) &&
626	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
627	>	(v = e.getValue()) != null &&
628	>	(k == key || k.equals(key)) &&
629	>	(v == (u = val) || v.equals(u)));
630	>	}
631	>
632	>	/**
633	>	* Virtualized support for map.get(); overridden in subclasses.
634	>	*/
635	>	Node<K,V> find(int h, Object k) {
636	>	Node<K,V> e = this;
637	>	if (k != null) {
638	>	do {
639	>	K ek;
640	>	if (e.hash == h &&
641	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
642	>	return e;
643	>	} while ((e = e.next) != null);
644	>	}
645	>	return null;
646		}
647		}
648
649	+	/* ---------------- Static utilities -------------- */
650	+
651		/**
652	<	* Segments are specialized versions of hash tables.  This
653	<	* subclasses from ReentrantLock opportunistically, just to
654	<	* simplify some locking and avoid separate construction.
655	<	**/
656	<	static final class Segment<K,V> extends ReentrantLock implements Serializable {
657	<	/*
658	<	* Segments maintain a table of entry lists that are ALWAYS
659	<	* kept in a consistent state, so can be read without locking.
660	<	* Next fields of nodes are immutable (final).  All list
661	<	* additions are performed at the front of each bin. This
662	<	* makes it easy to check changes, and also fast to traverse.
663	<	* When nodes would otherwise be changed, new nodes are
664	<	* created to replace them. This works well for hash tables
665	<	* since the bin lists tend to be short. (The average length
666	<	* is less than two for the default load factor threshold.)
667	<	*
668	<	* Read operations can thus proceed without locking, but rely
669	<	* 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	<	*/
652	>	* Spreads (XORs) higher bits of hash to lower and also forces top
653	>	* bit to 0. Because the table uses power-of-two masking, sets of
654	>	* hashes that vary only in bits above the current mask will
655	>	* always collide. (Among known examples are sets of Float keys
656	>	* holding consecutive whole numbers in small tables.)  So we
657	>	* apply a transform that spreads the impact of higher bits
658	>	* downward. There is a tradeoff between speed, utility, and
659	>	* quality of bit-spreading. Because many common sets of hashes
660	>	* are already reasonably distributed (so don't benefit from
661	>	* spreading), and because we use trees to handle large sets of
662	>	* collisions in bins, we just XOR some shifted bits in the
663	>	* cheapest possible way to reduce systematic lossage, as well as
664	>	* to incorporate impact of the highest bits that would otherwise
665	>	* never be used in index calculations because of table bounds.
666	>	*/
667	>	static final int spread(int h) {
668	>	return (h ^ (h >>> 16)) & HASH_BITS;
669	>	}
670
671	<	private static final long serialVersionUID = 2249069246763182397L;
671	>	/**
672	>	* Returns a power of two table size for the given desired capacity.
673	>	* See Hackers Delight, sec 3.2
674	>	*/
675	>	private static final int tableSizeFor(int c) {
676	>	int n = -1 >>> Integer.numberOfLeadingZeros(c - 1);
677	>	return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
678	>	}
679
680	<	/**
681	<	* The number of elements in this segment's region.
682	<	**/
683	<	transient volatile int count;
680	>	/**
681	>	* Returns x's Class if it is of the form "class C implements
682	>	* Comparable<C>", else null.
683	>	*/
684	>	static Class<?> comparableClassFor(Object x) {
685	>	if (x instanceof Comparable) {
686	>	Class<?> c; Type[] ts, as; ParameterizedType p;
687	>	if ((c = x.getClass()) == String.class) // bypass checks
688	>	return c;
689	>	if ((ts = c.getGenericInterfaces()) != null) {
690	>	for (Type t : ts) {
691	>	if ((t instanceof ParameterizedType) &&
692	>	((p = (ParameterizedType)t).getRawType() ==
693	>	Comparable.class) &&
694	>	(as = p.getActualTypeArguments()) != null &&
695	>	as.length == 1 && as[0] == c) // type arg is c
696	>	return c;
697	>	}
698	>	}
699	>	}
700	>	return null;
701	>	}
702
703	<	/**
704	<	* Number of updates that alter the size of the table. This is
705	<	* used during bulk-read methods to make sure they see a
706	<	* consistent snapshot: If modCounts change during a traversal
707	<	* of segments computing size or checking containsValue, then
708	<	* we might have an inconsistent view of state so (usually)
709	<	* must retry.
710	<	*/
711	<	transient int modCount;
703	>	/**
704	>	* Returns k.compareTo(x) if x matches kc (k's screened comparable
705	>	* class), else 0.
706	>	*/
707	>	@SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
708	>	static int compareComparables(Class<?> kc, Object k, Object x) {
709	>	return (x == null || x.getClass() != kc ? 0 :
710	>	((Comparable)k).compareTo(x));
711	>	}
712
713	<	/**
262	<	* The table is rehashed when its size exceeds this threshold.
263	<	* (The value of this field is always (int)(capacity *
264	<	* loadFactor).)
265	<	*/
266	<	transient int threshold;
713	>	/* ---------------- Table element access -------------- */
714
715	<	/**
716	<	* The per-segment table. Declared as a raw type, casted
717	<	* to HashEntry<K,V> on each use.
718	<	*/
719	<	transient volatile HashEntry[] table;
715	>	/*
716	>	* Atomic access methods are used for table elements as well as
717	>	* elements of in-progress next table while resizing.  All uses of
718	>	* the tab arguments must be null checked by callers.  All callers
719	>	* also paranoically precheck that tab's length is not zero (or an
720	>	* equivalent check), thus ensuring that any index argument taking
721	>	* the form of a hash value anded with (length - 1) is a valid
722	>	* index.  Note that, to be correct wrt arbitrary concurrency
723	>	* errors by users, these checks must operate on local variables,
724	>	* which accounts for some odd-looking inline assignments below.
725	>	* Note that calls to setTabAt always occur within locked regions,
726	>	* and so require only release ordering.
727	>	*/
728
729	<	/**
730	<	* The load factor for the hash table.  Even though this value
731	<	* is same for all segments, it is replicated to avoid needing
732	<	* links to outer object.
278	<	* @serial
279	<	*/
280	<	final float loadFactor;
729	>	@SuppressWarnings("unchecked")
730	>	static final <K,V> Node<K,V> tabAt(Node<K,V>[] tab, int i) {
731	>	return (Node<K,V>)U.getObjectAcquire(tab, ((long)i << ASHIFT) + ABASE);
732	>	}
733
734	<	Segment(int initialCapacity, float lf) {
735	<	loadFactor = lf;
736	<	setTable(new HashEntry[initialCapacity]);
737	<	}
734	>	static final <K,V> boolean casTabAt(Node<K,V>[] tab, int i,
735	>	Node<K,V> c, Node<K,V> v) {
736	>	return U.compareAndSetObject(tab, ((long)i << ASHIFT) + ABASE, c, v);
737	>	}
738
739	<	/**
740	<	* Set table to new HashEntry array.
741	<	* Call only while holding lock or in constructor.
290	<	**/
291	<	void setTable(HashEntry[] newTable) {
292	<	threshold = (int)(newTable.length * loadFactor);
293	<	table = newTable;
294	<	}
739	>	static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {
740	>	U.putObjectRelease(tab, ((long)i << ASHIFT) + ABASE, v);
741	>	}
742
743	<	/**
744	<	* Return properly casted first entry of bin for given hash
745	<	*/
746	<	HashEntry<K,V> getFirst(int hash) {
747	<	HashEntry[] tab = table;
748	<	return (HashEntry<K,V>) tab[hash & (tab.length - 1)];
743	>	/* ---------------- Fields -------------- */
744	>
745	>	/**
746	>	* The array of bins. Lazily initialized upon first insertion.
747	>	* Size is always a power of two. Accessed directly by iterators.
748	>	*/
749	>	transient volatile Node<K,V>[] table;
750	>
751	>	/**
752	>	* The next table to use; non-null only while resizing.
753	>	*/
754	>	private transient volatile Node<K,V>[] nextTable;
755	>
756	>	/**
757	>	* Base counter value, used mainly when there is no contention,
758	>	* but also as a fallback during table initialization
759	>	* races. Updated via CAS.
760	>	*/
761	>	private transient volatile long baseCount;
762	>
763	>	/**
764	>	* Table initialization and resizing control.  When negative, the
765	>	* table is being initialized or resized: -1 for initialization,
766	>	* else -(1 + the number of active resizing threads).  Otherwise,
767	>	* when table is null, holds the initial table size to use upon
768	>	* creation, or 0 for default. After initialization, holds the
769	>	* next element count value upon which to resize the table.
770	>	*/
771	>	private transient volatile int sizeCtl;
772	>
773	>	/**
774	>	* The next table index (plus one) to split while resizing.
775	>	*/
776	>	private transient volatile int transferIndex;
777	>
778	>	/**
779	>	* Spinlock (locked via CAS) used when resizing and/or creating CounterCells.
780	>	*/
781	>	private transient volatile int cellsBusy;
782	>
783	>	/**
784	>	* Table of counter cells. When non-null, size is a power of 2.
785	>	*/
786	>	private transient volatile CounterCell[] counterCells;
787	>
788	>	// views
789	>	private transient KeySetView<K,V> keySet;
790	>	private transient ValuesView<K,V> values;
791	>	private transient EntrySetView<K,V> entrySet;
792	>
793	>
794	>	/* ---------------- Public operations -------------- */
795	>
796	>	/**
797	>	* Creates a new, empty map with the default initial table size (16).
798	>	*/
799	>	public ConcurrentHashMap() {
800	>	}
801	>
802	>	/**
803	>	* Creates a new, empty map with an initial table size
804	>	* accommodating the specified number of elements without the need
805	>	* to dynamically resize.
806	>	*
807	>	* @param initialCapacity The implementation performs internal
808	>	* sizing to accommodate this many elements.
809	>	* @throws IllegalArgumentException if the initial capacity of
810	>	* elements is negative
811	>	*/
812	>	public ConcurrentHashMap(int initialCapacity) {
813	>	this(initialCapacity, LOAD_FACTOR, 1);
814	>	}
815	>
816	>	/**
817	>	* Creates a new map with the same mappings as the given map.
818	>	*
819	>	* @param m the map
820	>	*/
821	>	public ConcurrentHashMap(Map<? extends K, ? extends V> m) {
822	>	this.sizeCtl = DEFAULT_CAPACITY;
823	>	putAll(m);
824	>	}
825	>
826	>	/**
827	>	* Creates a new, empty map with an initial table size based on
828	>	* the given number of elements ({@code initialCapacity}) and
829	>	* initial table density ({@code loadFactor}).
830	>	*
831	>	* @param initialCapacity the initial capacity. The implementation
832	>	* performs internal sizing to accommodate this many elements,
833	>	* given the specified load factor.
834	>	* @param loadFactor the load factor (table density) for
835	>	* establishing the initial table size
836	>	* @throws IllegalArgumentException if the initial capacity of
837	>	* elements is negative or the load factor is nonpositive
838	>	*
839	>	* @since 1.6
840	>	*/
841	>	public ConcurrentHashMap(int initialCapacity, float loadFactor) {
842	>	this(initialCapacity, loadFactor, 1);
843	>	}
844	>
845	>	/**
846	>	* Creates a new, empty map with an initial table size based on
847	>	* the given number of elements ({@code initialCapacity}), initial
848	>	* table density ({@code loadFactor}), and number of concurrently
849	>	* updating threads ({@code concurrencyLevel}).
850	>	*
851	>	* @param initialCapacity the initial capacity. The implementation
852	>	* performs internal sizing to accommodate this many elements,
853	>	* given the specified load factor.
854	>	* @param loadFactor the load factor (table density) for
855	>	* establishing the initial table size
856	>	* @param concurrencyLevel the estimated number of concurrently
857	>	* updating threads. The implementation may use this value as
858	>	* a sizing hint.
859	>	* @throws IllegalArgumentException if the initial capacity is
860	>	* negative or the load factor or concurrencyLevel are
861	>	* nonpositive
862	>	*/
863	>	public ConcurrentHashMap(int initialCapacity,
864	>	float loadFactor, int concurrencyLevel) {
865	>	if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
866	>	throw new IllegalArgumentException();
867	>	if (initialCapacity < concurrencyLevel)   // Use at least as many bins
868	>	initialCapacity = concurrencyLevel;   // as estimated threads
869	>	long size = (long)(1.0 + (long)initialCapacity / loadFactor);
870	>	int cap = (size >= (long)MAXIMUM_CAPACITY) ?
871	>	MAXIMUM_CAPACITY : tableSizeFor((int)size);
872	>	this.sizeCtl = cap;
873	>	}
874	>
875	>	// Original (since JDK1.2) Map methods
876	>
877	>	/**
878	>	* {@inheritDoc}
879	>	*/
880	>	public int size() {
881	>	long n = sumCount();
882	>	return ((n < 0L) ? 0 :
883	>	(n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE :
884	>	(int)n);
885	>	}
886	>
887	>	/**
888	>	* {@inheritDoc}
889	>	*/
890	>	public boolean isEmpty() {
891	>	return sumCount() <= 0L; // ignore transient negative values
892	>	}
893	>
894	>	/**
895	>	* Returns the value to which the specified key is mapped,
896	>	* or {@code null} if this map contains no mapping for the key.
897	>	*
898	>	* <p>More formally, if this map contains a mapping from a key
899	>	* {@code k} to a value {@code v} such that {@code key.equals(k)},
900	>	* then this method returns {@code v}; otherwise it returns
901	>	* {@code null}.  (There can be at most one such mapping.)
902	>	*
903	>	* @throws NullPointerException if the specified key is null
904	>	*/
905	>	public V get(Object key) {
906	>	Node<K,V>[] tab; Node<K,V> e, p; int n, eh; K ek;
907	>	int h = spread(key.hashCode());
908	>	if ((tab = table) != null && (n = tab.length) > 0 &&
909	>	(e = tabAt(tab, (n - 1) & h)) != null) {
910	>	if ((eh = e.hash) == h) {
911	>	if ((ek = e.key) == key || (ek != null && key.equals(ek)))
912	>	return e.val;
913	>	}
914	>	else if (eh < 0)
915	>	return (p = e.find(h, key)) != null ? p.val : null;
916	>	while ((e = e.next) != null) {
917	>	if (e.hash == h &&
918	>	((ek = e.key) == key || (ek != null && key.equals(ek))))
919	>	return e.val;
920	>	}
921		}
922	+	return null;
923	+	}
924
925	<	/**
926	<	* Read value field of an entry under lock. Called if value
927	<	* field ever appears to be null. This is possible only if a
928	<	* compiler happens to reorder a HashEntry initialization with
929	<	* its table assignment, which is legal under memory model
930	<	* but is not known to ever occur.
931	<	*/
932	<	V readValueUnderLock(HashEntry<K,V> e) {
933	<	lock();
934	<	try {
935	<	return e.value;
936	<	} finally {
937	<	unlock();
925	>	/**
926	>	* Tests if the specified object is a key in this table.
927	>	*
928	>	* @param  key possible key
929	>	* @return {@code true} if and only if the specified object
930	>	*         is a key in this table, as determined by the
931	>	*         {@code equals} method; {@code false} otherwise
932	>	* @throws NullPointerException if the specified key is null
933	>	*/
934	>	public boolean containsKey(Object key) {
935	>	return get(key) != null;
936	>	}
937	>
938	>	/**
939	>	* Returns {@code true} if this map maps one or more keys to the
940	>	* specified value. Note: This method may require a full traversal
941	>	* of the map, and is much slower than method {@code containsKey}.
942	>	*
943	>	* @param value value whose presence in this map is to be tested
944	>	* @return {@code true} if this map maps one or more keys to the
945	>	*         specified value
946	>	* @throws NullPointerException if the specified value is null
947	>	*/
948	>	public boolean containsValue(Object value) {
949	>	if (value == null)
950	>	throw new NullPointerException();
951	>	Node<K,V>[] t;
952	>	if ((t = table) != null) {
953	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
954	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
955	>	V v;
956	>	if ((v = p.val) == value || (v != null && value.equals(v)))
957	>	return true;
958		}
959		}
960	+	return false;
961	+	}
962
963	<	/* Specialized implementations of map methods */
963	>	/**
964	>	* Maps the specified key to the specified value in this table.
965	>	* Neither the key nor the value can be null.
966	>	*
967	>	* <p>The value can be retrieved by calling the {@code get} method
968	>	* with a key that is equal to the original key.
969	>	*
970	>	* @param key key with which the specified value is to be associated
971	>	* @param value value to be associated with the specified key
972	>	* @return the previous value associated with {@code key}, or
973	>	*         {@code null} if there was no mapping for {@code key}
974	>	* @throws NullPointerException if the specified key or value is null
975	>	*/
976	>	public V put(K key, V value) {
977	>	return putVal(key, value, false);
978	>	}
979
980	<	V get(Object key, int hash) {
981	<	if (count != 0) { // read-volatile
982	<	HashEntry<K,V> e = getFirst(hash);
983	<	while (e != null) {
984	<	if (e.hash == hash && key.equals(e.key)) {
985	<	V v = e.value;
986	<	if (v != null)
987	<	return v;
988	<	return readValueUnderLock(e); // recheck
980	>	/** Implementation for put and putIfAbsent */
981	>	final V putVal(K key, V value, boolean onlyIfAbsent) {
982	>	if (key == null || value == null) throw new NullPointerException();
983	>	int hash = spread(key.hashCode());
984	>	int binCount = 0;
985	>	for (Node<K,V>[] tab = table;;) {
986	>	Node<K,V> f; int n, i, fh; K fk; V fv;
987	>	if (tab == null || (n = tab.length) == 0)
988	>	tab = initTable();
989	>	else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
990	>	if (casTabAt(tab, i, null, new Node<K,V>(hash, key, value)))
991	>	break;                   // no lock when adding to empty bin
992	>	}
993	>	else if ((fh = f.hash) == MOVED)
994	>	tab = helpTransfer(tab, f);
995	>	else if (onlyIfAbsent // check first node without acquiring lock
996	>	&& fh == hash
997	>	&& ((fk = f.key) == key || (fk != null && key.equals(fk)))
998	>	&& (fv = f.val) != null)
999	>	return fv;
1000	>	else {
1001	>	V oldVal = null;
1002	>	synchronized (f) {
1003	>	if (tabAt(tab, i) == f) {
1004	>	if (fh >= 0) {
1005	>	binCount = 1;
1006	>	for (Node<K,V> e = f;; ++binCount) {
1007	>	K ek;
1008	>	if (e.hash == hash &&
1009	>	((ek = e.key) == key ||
1010	>	(ek != null && key.equals(ek)))) {
1011	>	oldVal = e.val;
1012	>	if (!onlyIfAbsent)
1013	>	e.val = value;
1014	>	break;
1015	>	}
1016	>	Node<K,V> pred = e;
1017	>	if ((e = e.next) == null) {
1018	>	pred.next = new Node<K,V>(hash, key, value);
1019	>	break;
1020	>	}
1021	>	}
1022	>	}
1023	>	else if (f instanceof TreeBin) {
1024	>	Node<K,V> p;
1025	>	binCount = 2;
1026	>	if ((p = ((TreeBin<K,V>)f).putTreeVal(hash, key,
1027	>	value)) != null) {
1028	>	oldVal = p.val;
1029	>	if (!onlyIfAbsent)
1030	>	p.val = value;
1031	>	}
1032	>	}
1033	>	else if (f instanceof ReservationNode)
1034	>	throw new IllegalStateException("Recursive update");
1035		}
1036	<	e = e.next;
1036	>	}
1037	>	if (binCount != 0) {
1038	>	if (binCount >= TREEIFY_THRESHOLD)
1039	>	treeifyBin(tab, i);
1040	>	if (oldVal != null)
1041	>	return oldVal;
1042	>	break;
1043		}
1044		}
335	–	return null;
1045		}
1046	+	addCount(1L, binCount);
1047	+	return null;
1048	+	}
1049
1050	<	boolean containsKey(Object key, int hash) {
1051	<	if (count != 0) { // read-volatile
1052	<	HashEntry<K,V> e = getFirst(hash);
1053	<	while (e != null) {
1054	<	if (e.hash == hash && key.equals(e.key))
1055	<	return true;
1056	<	e = e.next;
1050	>	/**
1051	>	* Copies all of the mappings from the specified map to this one.
1052	>	* These mappings replace any mappings that this map had for any of the
1053	>	* keys currently in the specified map.
1054	>	*
1055	>	* @param m mappings to be stored in this map
1056	>	*/
1057	>	public void putAll(Map<? extends K, ? extends V> m) {
1058	>	tryPresize(m.size());
1059	>	for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
1060	>	putVal(e.getKey(), e.getValue(), false);
1061	>	}
1062	>
1063	>	/**
1064	>	* Removes the key (and its corresponding value) from this map.
1065	>	* This method does nothing if the key is not in the map.
1066	>	*
1067	>	* @param  key the key that needs to be removed
1068	>	* @return the previous value associated with {@code key}, or
1069	>	*         {@code null} if there was no mapping for {@code key}
1070	>	* @throws NullPointerException if the specified key is null
1071	>	*/
1072	>	public V remove(Object key) {
1073	>	return replaceNode(key, null, null);
1074	>	}
1075	>
1076	>	/**
1077	>	* Implementation for the four public remove/replace methods:
1078	>	* Replaces node value with v, conditional upon match of cv if
1079	>	* non-null.  If resulting value is null, delete.
1080	>	*/
1081	>	final V replaceNode(Object key, V value, Object cv) {
1082	>	int hash = spread(key.hashCode());
1083	>	for (Node<K,V>[] tab = table;;) {
1084	>	Node<K,V> f; int n, i, fh;
1085	>	if (tab == null || (n = tab.length) == 0 ||
1086	>	(f = tabAt(tab, i = (n - 1) & hash)) == null)
1087	>	break;
1088	>	else if ((fh = f.hash) == MOVED)
1089	>	tab = helpTransfer(tab, f);
1090	>	else {
1091	>	V oldVal = null;
1092	>	boolean validated = false;
1093	>	synchronized (f) {
1094	>	if (tabAt(tab, i) == f) {
1095	>	if (fh >= 0) {
1096	>	validated = true;
1097	>	for (Node<K,V> e = f, pred = null;;) {
1098	>	K ek;
1099	>	if (e.hash == hash &&
1100	>	((ek = e.key) == key ||
1101	>	(ek != null && key.equals(ek)))) {
1102	>	V ev = e.val;
1103	>	if (cv == null || cv == ev ||
1104	>	(ev != null && cv.equals(ev))) {
1105	>	oldVal = ev;
1106	>	if (value != null)
1107	>	e.val = value;
1108	>	else if (pred != null)
1109	>	pred.next = e.next;
1110	>	else
1111	>	setTabAt(tab, i, e.next);
1112	>	}
1113	>	break;
1114	>	}
1115	>	pred = e;
1116	>	if ((e = e.next) == null)
1117	>	break;
1118	>	}
1119	>	}
1120	>	else if (f instanceof TreeBin) {
1121	>	validated = true;
1122	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1123	>	TreeNode<K,V> r, p;
1124	>	if ((r = t.root) != null &&
1125	>	(p = r.findTreeNode(hash, key, null)) != null) {
1126	>	V pv = p.val;
1127	>	if (cv == null || cv == pv ||
1128	>	(pv != null && cv.equals(pv))) {
1129	>	oldVal = pv;
1130	>	if (value != null)
1131	>	p.val = value;
1132	>	else if (t.removeTreeNode(p))
1133	>	setTabAt(tab, i, untreeify(t.first));
1134	>	}
1135	>	}
1136	>	}
1137	>	else if (f instanceof ReservationNode)
1138	>	throw new IllegalStateException("Recursive update");
1139	>	}
1140	>	}
1141	>	if (validated) {
1142	>	if (oldVal != null) {
1143	>	if (value == null)
1144	>	addCount(-1L, -1);
1145	>	return oldVal;
1146	>	}
1147	>	break;
1148		}
1149		}
347	–	return false;
1150		}
1151	+	return null;
1152	+	}
1153
1154	<	boolean containsValue(Object value) {
1155	<	if (count != 0) { // read-volatile
1156	<	HashEntry[] tab = table;
1157	<	int len = tab.length;
1158	<	for (int i = 0 ; i < len; i++) {
1159	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i];
1160	<	e != null ;
1161	<	e = e.next) {
1162	<	V v = e.value;
1163	<	if (v == null) // recheck
1164	<	v = readValueUnderLock(e);
1165	<	if (value.equals(v))
1166	<	return true;
1154	>	/**
1155	>	* Removes all of the mappings from this map.
1156	>	*/
1157	>	public void clear() {
1158	>	long delta = 0L; // negative number of deletions
1159	>	int i = 0;
1160	>	Node<K,V>[] tab = table;
1161	>	while (tab != null && i < tab.length) {
1162	>	int fh;
1163	>	Node<K,V> f = tabAt(tab, i);
1164	>	if (f == null)
1165	>	++i;
1166	>	else if ((fh = f.hash) == MOVED) {
1167	>	tab = helpTransfer(tab, f);
1168	>	i = 0; // restart
1169	>	}
1170	>	else {
1171	>	synchronized (f) {
1172	>	if (tabAt(tab, i) == f) {
1173	>	Node<K,V> p = (fh >= 0 ? f :
1174	>	(f instanceof TreeBin) ?
1175	>	((TreeBin<K,V>)f).first : null);
1176	>	while (p != null) {
1177	>	--delta;
1178	>	p = p.next;
1179	>	}
1180	>	setTabAt(tab, i++, null);
1181		}
1182		}
1183		}
366	–	return false;
1184		}
1185	+	if (delta != 0L)
1186	+	addCount(delta, -1);
1187	+	}
1188
1189	<	boolean replace(K key, int hash, V oldValue, V newValue) {
1190	<	lock();
1191	<	try {
1192	<	HashEntry<K,V> e = getFirst(hash);
1193	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1194	<	e = e.next;
1195	<
1196	<	boolean replaced = false;
1197	<	if (e != null && oldValue.equals(e.value)) {
1198	<	replaced = true;
1199	<	e.value = newValue;
1200	<	}
1201	<	return replaced;
1202	<	} finally {
1203	<	unlock();
1189	>	/**
1190	>	* Returns a {@link Set} view of the keys contained in this map.
1191	>	* The set is backed by the map, so changes to the map are
1192	>	* reflected in the set, and vice-versa. The set supports element
1193	>	* removal, which removes the corresponding mapping from this map,
1194	>	* via the {@code Iterator.remove}, {@code Set.remove},
1195	>	* {@code removeAll}, {@code retainAll}, and {@code clear}
1196	>	* operations.  It does not support the {@code add} or
1197	>	* {@code addAll} operations.
1198	>	*
1199	>	* <p>The view's iterators and spliterators are
1200	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1201	>	*
1202	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
1203	>	* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
1204	>	*
1205	>	* @return the set view
1206	>	*/
1207	>	public KeySetView<K,V> keySet() {
1208	>	KeySetView<K,V> ks;
1209	>	if ((ks = keySet) != null) return ks;
1210	>	return keySet = new KeySetView<K,V>(this, null);
1211	>	}
1212	>
1213	>	/**
1214	>	* Returns a {@link Collection} view of the values contained in this map.
1215	>	* The collection is backed by the map, so changes to the map are
1216	>	* reflected in the collection, and vice-versa.  The collection
1217	>	* supports element removal, which removes the corresponding
1218	>	* mapping from this map, via the {@code Iterator.remove},
1219	>	* {@code Collection.remove}, {@code removeAll},
1220	>	* {@code retainAll}, and {@code clear} operations.  It does not
1221	>	* support the {@code add} or {@code addAll} operations.
1222	>	*
1223	>	* <p>The view's iterators and spliterators are
1224	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1225	>	*
1226	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT}
1227	>	* and {@link Spliterator#NONNULL}.
1228	>	*
1229	>	* @return the collection view
1230	>	*/
1231	>	public Collection<V> values() {
1232	>	ValuesView<K,V> vs;
1233	>	if ((vs = values) != null) return vs;
1234	>	return values = new ValuesView<K,V>(this);
1235	>	}
1236	>
1237	>	/**
1238	>	* Returns a {@link Set} view of the mappings contained in this map.
1239	>	* The set is backed by the map, so changes to the map are
1240	>	* reflected in the set, and vice-versa.  The set supports element
1241	>	* removal, which removes the corresponding mapping from the map,
1242	>	* via the {@code Iterator.remove}, {@code Set.remove},
1243	>	* {@code removeAll}, {@code retainAll}, and {@code clear}
1244	>	* operations.
1245	>	*
1246	>	* <p>The view's iterators and spliterators are
1247	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1248	>	*
1249	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
1250	>	* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
1251	>	*
1252	>	* @return the set view
1253	>	*/
1254	>	public Set<Map.Entry<K,V>> entrySet() {
1255	>	EntrySetView<K,V> es;
1256	>	if ((es = entrySet) != null) return es;
1257	>	return entrySet = new EntrySetView<K,V>(this);
1258	>	}
1259	>
1260	>	/**
1261	>	* Returns the hash code value for this {@link Map}, i.e.,
1262	>	* the sum of, for each key-value pair in the map,
1263	>	* {@code key.hashCode() ^ value.hashCode()}.
1264	>	*
1265	>	* @return the hash code value for this map
1266	>	*/
1267	>	public int hashCode() {
1268	>	int h = 0;
1269	>	Node<K,V>[] t;
1270	>	if ((t = table) != null) {
1271	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1272	>	for (Node<K,V> p; (p = it.advance()) != null; )
1273	>	h += p.key.hashCode() ^ p.val.hashCode();
1274	>	}
1275	>	return h;
1276	>	}
1277	>
1278	>	/**
1279	>	* Returns a string representation of this map.  The string
1280	>	* representation consists of a list of key-value mappings (in no
1281	>	* particular order) enclosed in braces ("{@code {}}").  Adjacent
1282	>	* mappings are separated by the characters {@code ", "} (comma
1283	>	* and space).  Each key-value mapping is rendered as the key
1284	>	* followed by an equals sign ("{@code =}") followed by the
1285	>	* associated value.
1286	>	*
1287	>	* @return a string representation of this map
1288	>	*/
1289	>	public String toString() {
1290	>	Node<K,V>[] t;
1291	>	int f = (t = table) == null ? 0 : t.length;
1292	>	Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1293	>	StringBuilder sb = new StringBuilder();
1294	>	sb.append('{');
1295	>	Node<K,V> p;
1296	>	if ((p = it.advance()) != null) {
1297	>	for (;;) {
1298	>	K k = p.key;
1299	>	V v = p.val;
1300	>	sb.append(k == this ? "(this Map)" : k);
1301	>	sb.append('=');
1302	>	sb.append(v == this ? "(this Map)" : v);
1303	>	if ((p = it.advance()) == null)
1304	>	break;
1305	>	sb.append(',').append(' ');
1306		}
1307		}
1308	+	return sb.append('}').toString();
1309	+	}
1310
1311	<	V replace(K key, int hash, V newValue) {
1312	<	lock();
1313	<	try {
1314	<	HashEntry<K,V> e = getFirst(hash);
1315	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1316	<	e = e.next;
1317	<
1318	<	V oldValue = null;
1319	<	if (e != null) {
1320	<	oldValue = e.value;
1321	<	e.value = newValue;
1322	<	}
1323	<	return oldValue;
1324	<	} finally {
1325	<	unlock();
1311	>	/**
1312	>	* Compares the specified object with this map for equality.
1313	>	* Returns {@code true} if the given object is a map with the same
1314	>	* mappings as this map.  This operation may return misleading
1315	>	* results if either map is concurrently modified during execution
1316	>	* of this method.
1317	>	*
1318	>	* @param o object to be compared for equality with this map
1319	>	* @return {@code true} if the specified object is equal to this map
1320	>	*/
1321	>	public boolean equals(Object o) {
1322	>	if (o != this) {
1323	>	if (!(o instanceof Map))
1324	>	return false;
1325	>	Map<?,?> m = (Map<?,?>) o;
1326	>	Node<K,V>[] t;
1327	>	int f = (t = table) == null ? 0 : t.length;
1328	>	Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
1329	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1330	>	V val = p.val;
1331	>	Object v = m.get(p.key);
1332	>	if (v == null || (v != val && !v.equals(val)))
1333	>	return false;
1334	>	}
1335	>	for (Map.Entry<?,?> e : m.entrySet()) {
1336	>	Object mk, mv, v;
1337	>	if ((mk = e.getKey()) == null ||
1338	>	(mv = e.getValue()) == null ||
1339	>	(v = get(mk)) == null ||
1340	>	(mv != v && !mv.equals(v)))
1341	>	return false;
1342		}
1343		}
1344	+	return true;
1345	+	}
1346
1347	+	/**
1348	+	* Stripped-down version of helper class used in previous version,
1349	+	* declared for the sake of serialization compatibility.
1350	+	*/
1351	+	static class Segment<K,V> extends ReentrantLock implements Serializable {
1352	+	private static final long serialVersionUID = 2249069246763182397L;
1353	+	final float loadFactor;
1354	+	Segment(float lf) { this.loadFactor = lf; }
1355	+	}
1356
1357	<	V put(K key, int hash, V value, boolean onlyIfAbsent) {
1358	<	lock();
1359	<	try {
1360	<	int c = count;
1361	<	if (c++ > threshold) // ensure capacity
1362	<	rehash();
1363	<	HashEntry[] tab = table;
1364	<	int index = hash & (tab.length - 1);
1365	<	HashEntry<K,V> first = (HashEntry<K,V>) tab[index];
1366	<	HashEntry<K,V> e = first;
1367	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1368	<	e = e.next;
1369	<
1370	<	V oldValue;
1371	<	if (e != null) {
1372	<	oldValue = e.value;
1373	<	if (!onlyIfAbsent)
1374	<	e.value = value;
1375	<	}
1357	>	/**
1358	>	* Saves this map to a stream (that is, serializes it).
1359	>	*
1360	>	* @param s the stream
1361	>	* @throws java.io.IOException if an I/O error occurs
1362	>	* @serialData
1363	>	* the serialized fields, followed by the key (Object) and value
1364	>	* (Object) for each key-value mapping, followed by a null pair.
1365	>	* The key-value mappings are emitted in no particular order.
1366	>	*/
1367	>	private void writeObject(java.io.ObjectOutputStream s)
1368	>	throws java.io.IOException {
1369	>	// For serialization compatibility
1370	>	// Emulate segment calculation from previous version of this class
1371	>	int sshift = 0;
1372	>	int ssize = 1;
1373	>	while (ssize < DEFAULT_CONCURRENCY_LEVEL) {
1374	>	++sshift;
1375	>	ssize <<= 1;
1376	>	}
1377	>	int segmentShift = 32 - sshift;
1378	>	int segmentMask = ssize - 1;
1379	>	@SuppressWarnings("unchecked")
1380	>	Segment<K,V>[] segments = (Segment<K,V>[])
1381	>	new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
1382	>	for (int i = 0; i < segments.length; ++i)
1383	>	segments[i] = new Segment<K,V>(LOAD_FACTOR);
1384	>	java.io.ObjectOutputStream.PutField streamFields = s.putFields();
1385	>	streamFields.put("segments", segments);
1386	>	streamFields.put("segmentShift", segmentShift);
1387	>	streamFields.put("segmentMask", segmentMask);
1388	>	s.writeFields();
1389	>
1390	>	Node<K,V>[] t;
1391	>	if ((t = table) != null) {
1392	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1393	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1394	>	s.writeObject(p.key);
1395	>	s.writeObject(p.val);
1396	>	}
1397	>	}
1398	>	s.writeObject(null);
1399	>	s.writeObject(null);
1400	>	}
1401	>
1402	>	/**
1403	>	* Reconstitutes this map from a stream (that is, deserializes it).
1404	>	* @param s the stream
1405	>	* @throws ClassNotFoundException if the class of a serialized object
1406	>	*         could not be found
1407	>	* @throws java.io.IOException if an I/O error occurs
1408	>	*/
1409	>	private void readObject(java.io.ObjectInputStream s)
1410	>	throws java.io.IOException, ClassNotFoundException {
1411	>	/*
1412	>	* To improve performance in typical cases, we create nodes
1413	>	* while reading, then place in table once size is known.
1414	>	* However, we must also validate uniqueness and deal with
1415	>	* overpopulated bins while doing so, which requires
1416	>	* specialized versions of putVal mechanics.
1417	>	*/
1418	>	sizeCtl = -1; // force exclusion for table construction
1419	>	s.defaultReadObject();
1420	>	long size = 0L;
1421	>	Node<K,V> p = null;
1422	>	for (;;) {
1423	>	@SuppressWarnings("unchecked")
1424	>	K k = (K) s.readObject();
1425	>	@SuppressWarnings("unchecked")
1426	>	V v = (V) s.readObject();
1427	>	if (k != null && v != null) {
1428	>	p = new Node<K,V>(spread(k.hashCode()), k, v, p);
1429	>	++size;
1430	>	}
1431	>	else
1432	>	break;
1433	>	}
1434	>	if (size == 0L)
1435	>	sizeCtl = 0;
1436	>	else {
1437	>	long ts = (long)(1.0 + size / LOAD_FACTOR);
1438	>	int n = (ts >= (long)MAXIMUM_CAPACITY) ?
1439	>	MAXIMUM_CAPACITY : tableSizeFor((int)ts);
1440	>	@SuppressWarnings("unchecked")
1441	>	Node<K,V>[] tab = (Node<K,V>[])new Node<?,?>[n];
1442	>	int mask = n - 1;
1443	>	long added = 0L;
1444	>	while (p != null) {
1445	>	boolean insertAtFront;
1446	>	Node<K,V> next = p.next, first;
1447	>	int h = p.hash, j = h & mask;
1448	>	if ((first = tabAt(tab, j)) == null)
1449	>	insertAtFront = true;
1450		else {
1451	<	oldValue = null;
1452	<	++modCount;
1453	<	tab[index] = new HashEntry<K,V>(key, hash, first, value);
1454	<	count = c; // write-volatile
1451	>	K k = p.key;
1452	>	if (first.hash < 0) {
1453	>	TreeBin<K,V> t = (TreeBin<K,V>)first;
1454	>	if (t.putTreeVal(h, k, p.val) == null)
1455	>	++added;
1456	>	insertAtFront = false;
1457	>	}
1458	>	else {
1459	>	int binCount = 0;
1460	>	insertAtFront = true;
1461	>	Node<K,V> q; K qk;
1462	>	for (q = first; q != null; q = q.next) {
1463	>	if (q.hash == h &&
1464	>	((qk = q.key) == k ||
1465	>	(qk != null && k.equals(qk)))) {
1466	>	insertAtFront = false;
1467	>	break;
1468	>	}
1469	>	++binCount;
1470	>	}
1471	>	if (insertAtFront && binCount >= TREEIFY_THRESHOLD) {
1472	>	insertAtFront = false;
1473	>	++added;
1474	>	p.next = first;
1475	>	TreeNode<K,V> hd = null, tl = null;
1476	>	for (q = p; q != null; q = q.next) {
1477	>	TreeNode<K,V> t = new TreeNode<K,V>
1478	>	(q.hash, q.key, q.val, null, null);
1479	>	if ((t.prev = tl) == null)
1480	>	hd = t;
1481	>	else
1482	>	tl.next = t;
1483	>	tl = t;
1484	>	}
1485	>	setTabAt(tab, j, new TreeBin<K,V>(hd));
1486	>	}
1487	>	}
1488		}
1489	<	return oldValue;
1490	<	} finally {
1491	<	unlock();
1489	>	if (insertAtFront) {
1490	>	++added;
1491	>	p.next = first;
1492	>	setTabAt(tab, j, p);
1493	>	}
1494	>	p = next;
1495		}
1496	+	table = tab;
1497	+	sizeCtl = n - (n >>> 2);
1498	+	baseCount = added;
1499		}
1500	+	}
1501
1502	<	void rehash() {
438	<	HashEntry[] oldTable = table;
439	<	int oldCapacity = oldTable.length;
440	<	if (oldCapacity >= MAXIMUM_CAPACITY)
441	<	return;
1502	>	// ConcurrentMap methods
1503
1504	<	/*
1505	<	* Reclassify nodes in each list to new Map.  Because we are
1506	<	* using power-of-two expansion, the elements from each bin
1507	<	* must either stay at same index, or move with a power of two
1508	<	* offset. We eliminate unnecessary node creation by catching
1509	<	* cases where old nodes can be reused because their next
1510	<	* fields won't change. Statistically, at the default
1511	<	* threshold, only about one-sixth of them need cloning when
1512	<	* a table doubles. The nodes they replace will be garbage
1513	<	* 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;
1504	>	/**
1505	>	* {@inheritDoc}
1506	>	*
1507	>	* @return the previous value associated with the specified key,
1508	>	*         or {@code null} if there was no mapping for the key
1509	>	* @throws NullPointerException if the specified key or value is null
1510	>	*/
1511	>	public V putIfAbsent(K key, V value) {
1512	>	return putVal(key, value, true);
1513	>	}
1514
1515	<	else {
1516	<	// Reuse trailing consecutive sequence at same slot
1517	<	HashEntry<K,V> lastRun = e;
1518	<	int lastIdx = idx;
1519	<	for (HashEntry<K,V> last = next;
1520	<	last != null;
1521	<	last = last.next) {
1522	<	int k = last.hash & sizeMask;
1523	<	if (k != lastIdx) {
1524	<	lastIdx = k;
1525	<	lastRun = last;
1515	>	/**
1516	>	* {@inheritDoc}
1517	>	*
1518	>	* @throws NullPointerException if the specified key is null
1519	>	*/
1520	>	public boolean remove(Object key, Object value) {
1521	>	if (key == null)
1522	>	throw new NullPointerException();
1523	>	return value != null && replaceNode(key, null, value) != null;
1524	>	}
1525	>
1526	>	/**
1527	>	* {@inheritDoc}
1528	>	*
1529	>	* @throws NullPointerException if any of the arguments are null
1530	>	*/
1531	>	public boolean replace(K key, V oldValue, V newValue) {
1532	>	if (key == null || oldValue == null || newValue == null)
1533	>	throw new NullPointerException();
1534	>	return replaceNode(key, newValue, oldValue) != null;
1535	>	}
1536	>
1537	>	/**
1538	>	* {@inheritDoc}
1539	>	*
1540	>	* @return the previous value associated with the specified key,
1541	>	*         or {@code null} if there was no mapping for the key
1542	>	* @throws NullPointerException if the specified key or value is null
1543	>	*/
1544	>	public V replace(K key, V value) {
1545	>	if (key == null || value == null)
1546	>	throw new NullPointerException();
1547	>	return replaceNode(key, value, null);
1548	>	}
1549	>
1550	>	// Overrides of JDK8+ Map extension method defaults
1551	>
1552	>	/**
1553	>	* Returns the value to which the specified key is mapped, or the
1554	>	* given default value if this map contains no mapping for the
1555	>	* key.
1556	>	*
1557	>	* @param key the key whose associated value is to be returned
1558	>	* @param defaultValue the value to return if this map contains
1559	>	* no mapping for the given key
1560	>	* @return the mapping for the key, if present; else the default value
1561	>	* @throws NullPointerException if the specified key is null
1562	>	*/
1563	>	public V getOrDefault(Object key, V defaultValue) {
1564	>	V v;
1565	>	return (v = get(key)) == null ? defaultValue : v;
1566	>	}
1567	>
1568	>	public void forEach(BiConsumer<? super K, ? super V> action) {
1569	>	if (action == null) throw new NullPointerException();
1570	>	Node<K,V>[] t;
1571	>	if ((t = table) != null) {
1572	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1573	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1574	>	action.accept(p.key, p.val);
1575	>	}
1576	>	}
1577	>	}
1578	>
1579	>	public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1580	>	if (function == null) throw new NullPointerException();
1581	>	Node<K,V>[] t;
1582	>	if ((t = table) != null) {
1583	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1584	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1585	>	V oldValue = p.val;
1586	>	for (K key = p.key;;) {
1587	>	V newValue = function.apply(key, oldValue);
1588	>	if (newValue == null)
1589	>	throw new NullPointerException();
1590	>	if (replaceNode(key, newValue, oldValue) != null ||
1591	>	(oldValue = get(key)) == null)
1592	>	break;
1593	>	}
1594	>	}
1595	>	}
1596	>	}
1597	>
1598	>	/**
1599	>	* Helper method for EntrySetView.removeIf.
1600	>	*/
1601	>	boolean removeEntryIf(Predicate<? super Entry<K,V>> function) {
1602	>	if (function == null) throw new NullPointerException();
1603	>	Node<K,V>[] t;
1604	>	boolean removed = false;
1605	>	if ((t = table) != null) {
1606	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1607	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1608	>	K k = p.key;
1609	>	V v = p.val;
1610	>	Map.Entry<K,V> e = new AbstractMap.SimpleImmutableEntry<>(k, v);
1611	>	if (function.test(e) && replaceNode(k, null, v) != null)
1612	>	removed = true;
1613	>	}
1614	>	}
1615	>	return removed;
1616	>	}
1617	>
1618	>	/**
1619	>	* Helper method for ValuesView.removeIf.
1620	>	*/
1621	>	boolean removeValueIf(Predicate<? super V> function) {
1622	>	if (function == null) throw new NullPointerException();
1623	>	Node<K,V>[] t;
1624	>	boolean removed = false;
1625	>	if ((t = table) != null) {
1626	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
1627	>	for (Node<K,V> p; (p = it.advance()) != null; ) {
1628	>	K k = p.key;
1629	>	V v = p.val;
1630	>	if (function.test(v) && replaceNode(k, null, v) != null)
1631	>	removed = true;
1632	>	}
1633	>	}
1634	>	return removed;
1635	>	}
1636	>
1637	>	/**
1638	>	* If the specified key is not already associated with a value,
1639	>	* attempts to compute its value using the given mapping function
1640	>	* and enters it into this map unless {@code null}.  The entire
1641	>	* method invocation is performed atomically, so the function is
1642	>	* applied at most once per key.  Some attempted update operations
1643	>	* on this map by other threads may be blocked while computation
1644	>	* is in progress, so the computation should be short and simple,
1645	>	* and must not attempt to update any other mappings of this map.
1646	>	*
1647	>	* @param key key with which the specified value is to be associated
1648	>	* @param mappingFunction the function to compute a value
1649	>	* @return the current (existing or computed) value associated with
1650	>	*         the specified key, or null if the computed value is null
1651	>	* @throws NullPointerException if the specified key or mappingFunction
1652	>	*         is null
1653	>	* @throws IllegalStateException if the computation detectably
1654	>	*         attempts a recursive update to this map that would
1655	>	*         otherwise never complete
1656	>	* @throws RuntimeException or Error if the mappingFunction does so,
1657	>	*         in which case the mapping is left unestablished
1658	>	*/
1659	>	public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
1660	>	if (key == null || mappingFunction == null)
1661	>	throw new NullPointerException();
1662	>	int h = spread(key.hashCode());
1663	>	V val = null;
1664	>	int binCount = 0;
1665	>	for (Node<K,V>[] tab = table;;) {
1666	>	Node<K,V> f; int n, i, fh; K fk; V fv;
1667	>	if (tab == null || (n = tab.length) == 0)
1668	>	tab = initTable();
1669	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1670	>	Node<K,V> r = new ReservationNode<K,V>();
1671	>	synchronized (r) {
1672	>	if (casTabAt(tab, i, null, r)) {
1673	>	binCount = 1;
1674	>	Node<K,V> node = null;
1675	>	try {
1676	>	if ((val = mappingFunction.apply(key)) != null)
1677	>	node = new Node<K,V>(h, key, val);
1678	>	} finally {
1679	>	setTabAt(tab, i, node);
1680	>	}
1681	>	}
1682	>	}
1683	>	if (binCount != 0)
1684	>	break;
1685	>	}
1686	>	else if ((fh = f.hash) == MOVED)
1687	>	tab = helpTransfer(tab, f);
1688	>	else if (fh == h    // check first node without acquiring lock
1689	>	&& ((fk = f.key) == key || (fk != null && key.equals(fk)))
1690	>	&& (fv = f.val) != null)
1691	>	return fv;
1692	>	else {
1693	>	boolean added = false;
1694	>	synchronized (f) {
1695	>	if (tabAt(tab, i) == f) {
1696	>	if (fh >= 0) {
1697	>	binCount = 1;
1698	>	for (Node<K,V> e = f;; ++binCount) {
1699	>	K ek;
1700	>	if (e.hash == h &&
1701	>	((ek = e.key) == key ||
1702	>	(ek != null && key.equals(ek)))) {
1703	>	val = e.val;
1704	>	break;
1705	>	}
1706	>	Node<K,V> pred = e;
1707	>	if ((e = e.next) == null) {
1708	>	if ((val = mappingFunction.apply(key)) != null) {
1709	>	if (pred.next != null)
1710	>	throw new IllegalStateException("Recursive update");
1711	>	added = true;
1712	>	pred.next = new Node<K,V>(h, key, val);
1713	>	}
1714	>	break;
1715	>	}
1716	>	}
1717	>	}
1718	>	else if (f instanceof TreeBin) {
1719	>	binCount = 2;
1720	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1721	>	TreeNode<K,V> r, p;
1722	>	if ((r = t.root) != null &&
1723	>	(p = r.findTreeNode(h, key, null)) != null)
1724	>	val = p.val;
1725	>	else if ((val = mappingFunction.apply(key)) != null) {
1726	>	added = true;
1727	>	t.putTreeVal(h, key, val);
1728		}
1729		}
1730	<	newTable[lastIdx] = lastRun;
1730	>	else if (f instanceof ReservationNode)
1731	>	throw new IllegalStateException("Recursive update");
1732	>	}
1733	>	}
1734	>	if (binCount != 0) {
1735	>	if (binCount >= TREEIFY_THRESHOLD)
1736	>	treeifyBin(tab, i);
1737	>	if (!added)
1738	>	return val;
1739	>	break;
1740	>	}
1741	>	}
1742	>	}
1743	>	if (val != null)
1744	>	addCount(1L, binCount);
1745	>	return val;
1746	>	}
1747
1748	<	// Clone all remaining nodes
1749	<	for (HashEntry<K,V> p = e; p != lastRun; p = p.next) {
1750	<	int k = p.hash & sizeMask;
1751	<	HashEntry<K,V> n = (HashEntry<K,V>)newTable[k];
1752	<	newTable[k] = new HashEntry<K,V>(p.key, p.hash,
1753	<	n, p.value);
1748	>	/**
1749	>	* If the value for the specified key is present, attempts to
1750	>	* compute a new mapping given the key and its current mapped
1751	>	* value.  The entire method invocation is performed atomically.
1752	>	* Some attempted update operations on this map by other threads
1753	>	* may be blocked while computation is in progress, so the
1754	>	* computation should be short and simple, and must not attempt to
1755	>	* update any other mappings of this map.
1756	>	*
1757	>	* @param key key with which a value may be associated
1758	>	* @param remappingFunction the function to compute a value
1759	>	* @return the new value associated with the specified key, or null if none
1760	>	* @throws NullPointerException if the specified key or remappingFunction
1761	>	*         is null
1762	>	* @throws IllegalStateException if the computation detectably
1763	>	*         attempts a recursive update to this map that would
1764	>	*         otherwise never complete
1765	>	* @throws RuntimeException or Error if the remappingFunction does so,
1766	>	*         in which case the mapping is unchanged
1767	>	*/
1768	>	public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1769	>	if (key == null || remappingFunction == null)
1770	>	throw new NullPointerException();
1771	>	int h = spread(key.hashCode());
1772	>	V val = null;
1773	>	int delta = 0;
1774	>	int binCount = 0;
1775	>	for (Node<K,V>[] tab = table;;) {
1776	>	Node<K,V> f; int n, i, fh;
1777	>	if (tab == null || (n = tab.length) == 0)
1778	>	tab = initTable();
1779	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null)
1780	>	break;
1781	>	else if ((fh = f.hash) == MOVED)
1782	>	tab = helpTransfer(tab, f);
1783	>	else {
1784	>	synchronized (f) {
1785	>	if (tabAt(tab, i) == f) {
1786	>	if (fh >= 0) {
1787	>	binCount = 1;
1788	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1789	>	K ek;
1790	>	if (e.hash == h &&
1791	>	((ek = e.key) == key ||
1792	>	(ek != null && key.equals(ek)))) {
1793	>	val = remappingFunction.apply(key, e.val);
1794	>	if (val != null)
1795	>	e.val = val;
1796	>	else {
1797	>	delta = -1;
1798	>	Node<K,V> en = e.next;
1799	>	if (pred != null)
1800	>	pred.next = en;
1801	>	else
1802	>	setTabAt(tab, i, en);
1803	>	}
1804	>	break;
1805	>	}
1806	>	pred = e;
1807	>	if ((e = e.next) == null)
1808	>	break;
1809	>	}
1810	>	}
1811	>	else if (f instanceof TreeBin) {
1812	>	binCount = 2;
1813	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1814	>	TreeNode<K,V> r, p;
1815	>	if ((r = t.root) != null &&
1816	>	(p = r.findTreeNode(h, key, null)) != null) {
1817	>	val = remappingFunction.apply(key, p.val);
1818	>	if (val != null)
1819	>	p.val = val;
1820	>	else {
1821	>	delta = -1;
1822	>	if (t.removeTreeNode(p))
1823	>	setTabAt(tab, i, untreeify(t.first));
1824	>	}
1825	>	}
1826		}
1827	+	else if (f instanceof ReservationNode)
1828	+	throw new IllegalStateException("Recursive update");
1829		}
1830		}
1831	+	if (binCount != 0)
1832	+	break;
1833		}
498	–	table = newTable;
1834		}
1835	+	if (delta != 0)
1836	+	addCount((long)delta, binCount);
1837	+	return val;
1838	+	}
1839
1840	<	/**
1841	<	* Remove; match on key only if value null, else match both.
1842	<	*/
1843	<	V remove(Object key, int hash, Object value) {
1844	<	lock();
1845	<	try {
1846	<	int c = count - 1;
1847	<	HashEntry[] tab = table;
1848	<	int index = hash & (tab.length - 1);
1849	<	HashEntry<K,V> first = (HashEntry<K,V>)tab[index];
1850	<	HashEntry<K,V> e = first;
1851	<	while (e != null && (e.hash != hash || !key.equals(e.key)))
1852	<	e = e.next;
1853	<
1854	<	V oldValue = null;
1855	<	if (e != null) {
1856	<	V v = e.value;
1857	<	if (value == null || value.equals(v)) {
1858	<	oldValue = v;
1859	<	// All entries following removed node can stay
1860	<	// in list, but all preceding ones need to be
1861	<	// cloned.
1862	<	++modCount;
1863	<	HashEntry<K,V> newFirst = e.next;
1864	<	for (HashEntry<K,V> p = first; p != e; p = p.next)
1865	<	newFirst = new HashEntry<K,V>(p.key, p.hash,
1866	<	newFirst, p.value);
1867	<	tab[index] = newFirst;
1868	<	count = c; // write-volatile
1840	>	/**
1841	>	* Attempts to compute a mapping for the specified key and its
1842	>	* current mapped value (or {@code null} if there is no current
1843	>	* mapping). The entire method invocation is performed atomically.
1844	>	* Some attempted update operations on this map by other threads
1845	>	* may be blocked while computation is in progress, so the
1846	>	* computation should be short and simple, and must not attempt to
1847	>	* update any other mappings of this Map.
1848	>	*
1849	>	* @param key key with which the specified value is to be associated
1850	>	* @param remappingFunction the function to compute a value
1851	>	* @return the new value associated with the specified key, or null if none
1852	>	* @throws NullPointerException if the specified key or remappingFunction
1853	>	*         is null
1854	>	* @throws IllegalStateException if the computation detectably
1855	>	*         attempts a recursive update to this map that would
1856	>	*         otherwise never complete
1857	>	* @throws RuntimeException or Error if the remappingFunction does so,
1858	>	*         in which case the mapping is unchanged
1859	>	*/
1860	>	public V compute(K key,
1861	>	BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1862	>	if (key == null || remappingFunction == null)
1863	>	throw new NullPointerException();
1864	>	int h = spread(key.hashCode());
1865	>	V val = null;
1866	>	int delta = 0;
1867	>	int binCount = 0;
1868	>	for (Node<K,V>[] tab = table;;) {
1869	>	Node<K,V> f; int n, i, fh;
1870	>	if (tab == null || (n = tab.length) == 0)
1871	>	tab = initTable();
1872	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
1873	>	Node<K,V> r = new ReservationNode<K,V>();
1874	>	synchronized (r) {
1875	>	if (casTabAt(tab, i, null, r)) {
1876	>	binCount = 1;
1877	>	Node<K,V> node = null;
1878	>	try {
1879	>	if ((val = remappingFunction.apply(key, null)) != null) {
1880	>	delta = 1;
1881	>	node = new Node<K,V>(h, key, val);
1882	>	}
1883	>	} finally {
1884	>	setTabAt(tab, i, node);
1885	>	}
1886		}
1887		}
1888	<	return oldValue;
1889	<	} finally {
1890	<	unlock();
1888	>	if (binCount != 0)
1889	>	break;
1890	>	}
1891	>	else if ((fh = f.hash) == MOVED)
1892	>	tab = helpTransfer(tab, f);
1893	>	else {
1894	>	synchronized (f) {
1895	>	if (tabAt(tab, i) == f) {
1896	>	if (fh >= 0) {
1897	>	binCount = 1;
1898	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
1899	>	K ek;
1900	>	if (e.hash == h &&
1901	>	((ek = e.key) == key ||
1902	>	(ek != null && key.equals(ek)))) {
1903	>	val = remappingFunction.apply(key, e.val);
1904	>	if (val != null)
1905	>	e.val = val;
1906	>	else {
1907	>	delta = -1;
1908	>	Node<K,V> en = e.next;
1909	>	if (pred != null)
1910	>	pred.next = en;
1911	>	else
1912	>	setTabAt(tab, i, en);
1913	>	}
1914	>	break;
1915	>	}
1916	>	pred = e;
1917	>	if ((e = e.next) == null) {
1918	>	val = remappingFunction.apply(key, null);
1919	>	if (val != null) {
1920	>	if (pred.next != null)
1921	>	throw new IllegalStateException("Recursive update");
1922	>	delta = 1;
1923	>	pred.next = new Node<K,V>(h, key, val);
1924	>	}
1925	>	break;
1926	>	}
1927	>	}
1928	>	}
1929	>	else if (f instanceof TreeBin) {
1930	>	binCount = 1;
1931	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
1932	>	TreeNode<K,V> r, p;
1933	>	if ((r = t.root) != null)
1934	>	p = r.findTreeNode(h, key, null);
1935	>	else
1936	>	p = null;
1937	>	V pv = (p == null) ? null : p.val;
1938	>	val = remappingFunction.apply(key, pv);
1939	>	if (val != null) {
1940	>	if (p != null)
1941	>	p.val = val;
1942	>	else {
1943	>	delta = 1;
1944	>	t.putTreeVal(h, key, val);
1945	>	}
1946	>	}
1947	>	else if (p != null) {
1948	>	delta = -1;
1949	>	if (t.removeTreeNode(p))
1950	>	setTabAt(tab, i, untreeify(t.first));
1951	>	}
1952	>	}
1953	>	else if (f instanceof ReservationNode)
1954	>	throw new IllegalStateException("Recursive update");
1955	>	}
1956	>	}
1957	>	if (binCount != 0) {
1958	>	if (binCount >= TREEIFY_THRESHOLD)
1959	>	treeifyBin(tab, i);
1960	>	break;
1961	>	}
1962		}
1963		}
1964	+	if (delta != 0)
1965	+	addCount((long)delta, binCount);
1966	+	return val;
1967	+	}
1968
1969	<	void clear() {
1970	<	if (count != 0) {
1971	<	lock();
1972	<	try {
1973	<	HashEntry[] tab = table;
1974	<	for (int i = 0; i < tab.length ; i++)
1975	<	tab[i] = null;
1976	<	++modCount;
1977	<	count = 0; // write-volatile
1978	<	} finally {
1979	<	unlock();
1969	>	/**
1970	>	* If the specified key is not already associated with a
1971	>	* (non-null) value, associates it with the given value.
1972	>	* Otherwise, replaces the value with the results of the given
1973	>	* remapping function, or removes if {@code null}. The entire
1974	>	* method invocation is performed atomically.  Some attempted
1975	>	* update operations on this map by other threads may be blocked
1976	>	* while computation is in progress, so the computation should be
1977	>	* short and simple, and must not attempt to update any other
1978	>	* mappings of this Map.
1979	>	*
1980	>	* @param key key with which the specified value is to be associated
1981	>	* @param value the value to use if absent
1982	>	* @param remappingFunction the function to recompute a value if present
1983	>	* @return the new value associated with the specified key, or null if none
1984	>	* @throws NullPointerException if the specified key or the
1985	>	*         remappingFunction is null
1986	>	* @throws RuntimeException or Error if the remappingFunction does so,
1987	>	*         in which case the mapping is unchanged
1988	>	*/
1989	>	public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1990	>	if (key == null || value == null || remappingFunction == null)
1991	>	throw new NullPointerException();
1992	>	int h = spread(key.hashCode());
1993	>	V val = null;
1994	>	int delta = 0;
1995	>	int binCount = 0;
1996	>	for (Node<K,V>[] tab = table;;) {
1997	>	Node<K,V> f; int n, i, fh;
1998	>	if (tab == null || (n = tab.length) == 0)
1999	>	tab = initTable();
2000	>	else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
2001	>	if (casTabAt(tab, i, null, new Node<K,V>(h, key, value))) {
2002	>	delta = 1;
2003	>	val = value;
2004	>	break;
2005	>	}
2006	>	}
2007	>	else if ((fh = f.hash) == MOVED)
2008	>	tab = helpTransfer(tab, f);
2009	>	else {
2010	>	synchronized (f) {
2011	>	if (tabAt(tab, i) == f) {
2012	>	if (fh >= 0) {
2013	>	binCount = 1;
2014	>	for (Node<K,V> e = f, pred = null;; ++binCount) {
2015	>	K ek;
2016	>	if (e.hash == h &&
2017	>	((ek = e.key) == key ||
2018	>	(ek != null && key.equals(ek)))) {
2019	>	val = remappingFunction.apply(e.val, value);
2020	>	if (val != null)
2021	>	e.val = val;
2022	>	else {
2023	>	delta = -1;
2024	>	Node<K,V> en = e.next;
2025	>	if (pred != null)
2026	>	pred.next = en;
2027	>	else
2028	>	setTabAt(tab, i, en);
2029	>	}
2030	>	break;
2031	>	}
2032	>	pred = e;
2033	>	if ((e = e.next) == null) {
2034	>	delta = 1;
2035	>	val = value;
2036	>	pred.next = new Node<K,V>(h, key, val);
2037	>	break;
2038	>	}
2039	>	}
2040	>	}
2041	>	else if (f instanceof TreeBin) {
2042	>	binCount = 2;
2043	>	TreeBin<K,V> t = (TreeBin<K,V>)f;
2044	>	TreeNode<K,V> r = t.root;
2045	>	TreeNode<K,V> p = (r == null) ? null :
2046	>	r.findTreeNode(h, key, null);
2047	>	val = (p == null) ? value :
2048	>	remappingFunction.apply(p.val, value);
2049	>	if (val != null) {
2050	>	if (p != null)
2051	>	p.val = val;
2052	>	else {
2053	>	delta = 1;
2054	>	t.putTreeVal(h, key, val);
2055	>	}
2056	>	}
2057	>	else if (p != null) {
2058	>	delta = -1;
2059	>	if (t.removeTreeNode(p))
2060	>	setTabAt(tab, i, untreeify(t.first));
2061	>	}
2062	>	}
2063	>	else if (f instanceof ReservationNode)
2064	>	throw new IllegalStateException("Recursive update");
2065	>	}
2066	>	}
2067	>	if (binCount != 0) {
2068	>	if (binCount >= TREEIFY_THRESHOLD)
2069	>	treeifyBin(tab, i);
2070	>	break;
2071		}
2072		}
2073		}
2074	+	if (delta != 0)
2075	+	addCount((long)delta, binCount);
2076	+	return val;
2077		}
2078
2079	+	// Hashtable legacy methods
2080
2081	+	/**
2082	+	* Tests if some key maps into the specified value in this table.
2083	+	*
2084	+	* <p>Note that this method is identical in functionality to
2085	+	* {@link #containsValue(Object)}, and exists solely to ensure
2086	+	* full compatibility with class {@link java.util.Hashtable},
2087	+	* which supported this method prior to introduction of the
2088	+	* Java Collections Framework.
2089	+	*
2090	+	* @param  value a value to search for
2091	+	* @return {@code true} if and only if some key maps to the
2092	+	*         {@code value} argument in this table as
2093	+	*         determined by the {@code equals} method;
2094	+	*         {@code false} otherwise
2095	+	* @throws NullPointerException if the specified value is null
2096	+	*/
2097	+	public boolean contains(Object value) {
2098	+	return containsValue(value);
2099	+	}
2100
2101	<	/* ---------------- Public operations -------------- */
2101	>	/**
2102	>	* Returns an enumeration of the keys in this table.
2103	>	*
2104	>	* @return an enumeration of the keys in this table
2105	>	* @see #keySet()
2106	>	*/
2107	>	public Enumeration<K> keys() {
2108	>	Node<K,V>[] t;
2109	>	int f = (t = table) == null ? 0 : t.length;
2110	>	return new KeyIterator<K,V>(t, f, 0, f, this);
2111	>	}
2112
2113		/**
2114	<	* Creates a new, empty map with the specified initial
560	<	* capacity, load factor, and concurrency level.
2114	>	* Returns an enumeration of the values in this table.
2115		*
2116	<	* @param initialCapacity the initial capacity. The implementation
2117	<	* 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.
2116	>	* @return an enumeration of the values in this table
2117	>	* @see #values()
2118		*/
2119	<	public ConcurrentHashMap(int initialCapacity,
2120	<	float loadFactor, int concurrencyLevel) {
2121	<	if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
2122	<	throw new IllegalArgumentException();
2119	>	public Enumeration<V> elements() {
2120	>	Node<K,V>[] t;
2121	>	int f = (t = table) == null ? 0 : t.length;
2122	>	return new ValueIterator<K,V>(t, f, 0, f, this);
2123	>	}
2124
2125	<	if (concurrencyLevel > MAX_SEGMENTS)
580	<	concurrencyLevel = MAX_SEGMENTS;
2125	>	// ConcurrentHashMap-only methods
2126
2127	<	// Find power-of-two sizes best matching arguments
2128	<	int sshift = 0;
2129	<	int ssize = 1;
2130	<	while (ssize < concurrencyLevel) {
2131	<	++sshift;
2132	<	ssize <<= 1;
2133	<	}
2134	<	segmentShift = 32 - sshift;
2135	<	segmentMask = ssize - 1;
2136	<	this.segments = new Segment[ssize];
2137	<
2138	<	if (initialCapacity > MAXIMUM_CAPACITY)
2139	<	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);
2127	>	/**
2128	>	* Returns the number of mappings. This method should be used
2129	>	* instead of {@link #size} because a ConcurrentHashMap may
2130	>	* contain more mappings than can be represented as an int. The
2131	>	* value returned is an estimate; the actual count may differ if
2132	>	* there are concurrent insertions or removals.
2133	>	*
2134	>	* @return the number of mappings
2135	>	* @since 1.8
2136	>	*/
2137	>	public long mappingCount() {
2138	>	long n = sumCount();
2139	>	return (n < 0L) ? 0L : n; // ignore transient negative values
2140		}
2141
2142		/**
2143	<	* Creates a new, empty map with the specified initial
2144	<	* capacity,  and with default load factor (<tt>0.75f</tt>)
609	<	* and concurrencyLevel (<tt>16</tt>).
2143	>	* Creates a new {@link Set} backed by a ConcurrentHashMap
2144	>	* from the given type to {@code Boolean.TRUE}.
2145		*
2146	<	* @param initialCapacity the initial capacity. The implementation
2147	<	* performs internal sizing to accommodate this many elements.
2146	>	* @param <K> the element type of the returned set
2147	>	* @return the new set
2148	>	* @since 1.8
2149	>	*/
2150	>	public static <K> KeySetView<K,Boolean> newKeySet() {
2151	>	return new KeySetView<K,Boolean>
2152	>	(new ConcurrentHashMap<K,Boolean>(), Boolean.TRUE);
2153	>	}
2154	>
2155	>	/**
2156	>	* Creates a new {@link Set} backed by a ConcurrentHashMap
2157	>	* from the given type to {@code Boolean.TRUE}.
2158	>	*
2159	>	* @param initialCapacity The implementation performs internal
2160	>	* sizing to accommodate this many elements.
2161	>	* @param <K> the element type of the returned set
2162	>	* @return the new set
2163		* @throws IllegalArgumentException if the initial capacity of
2164	<	* elements is negative.
2164	>	* elements is negative
2165	>	* @since 1.8
2166		*/
2167	<	public ConcurrentHashMap(int initialCapacity) {
2168	<	this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2167	>	public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
2168	>	return new KeySetView<K,Boolean>
2169	>	(new ConcurrentHashMap<K,Boolean>(initialCapacity), Boolean.TRUE);
2170		}
2171
2172		/**
2173	<	* Creates a new, empty map with a default initial capacity
2174	<	* (<tt>16</tt>), load factor (<tt>0.75f</tt>) and
2175	<	* concurrencyLevel (<tt>16</tt>).
2173	>	* Returns a {@link Set} view of the keys in this map, using the
2174	>	* given common mapped value for any additions (i.e., {@link
2175	>	* Collection#add} and {@link Collection#addAll(Collection)}).
2176	>	* This is of course only appropriate if it is acceptable to use
2177	>	* the same value for all additions from this view.
2178	>	*
2179	>	* @param mappedValue the mapped value to use for any additions
2180	>	* @return the set view
2181	>	* @throws NullPointerException if the mappedValue is null
2182		*/
2183	<	public ConcurrentHashMap() {
2184	<	this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2183	>	public KeySetView<K,V> keySet(V mappedValue) {
2184	>	if (mappedValue == null)
2185	>	throw new NullPointerException();
2186	>	return new KeySetView<K,V>(this, mappedValue);
2187		}
2188
2189	+	/* ---------------- Special Nodes -------------- */
2190	+
2191		/**
2192	<	* 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
2192	>	* A node inserted at head of bins during transfer operations.
2193		*/
2194	<	public ConcurrentHashMap(Map<? extends K, ? extends V> t) {
2195	<	this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1,
2196	<	DEFAULT_INITIAL_CAPACITY),
2197	<	DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
2198	<	putAll(t);
2194	>	static final class ForwardingNode<K,V> extends Node<K,V> {
2195	>	final Node<K,V>[] nextTable;
2196	>	ForwardingNode(Node<K,V>[] tab) {
2197	>	super(MOVED, null, null);
2198	>	this.nextTable = tab;
2199	>	}
2200	>
2201	>	Node<K,V> find(int h, Object k) {
2202	>	// loop to avoid arbitrarily deep recursion on forwarding nodes
2203	>	outer: for (Node<K,V>[] tab = nextTable;;) {
2204	>	Node<K,V> e; int n;
2205	>	if (k == null || tab == null || (n = tab.length) == 0 ||
2206	>	(e = tabAt(tab, (n - 1) & h)) == null)
2207	>	return null;
2208	>	for (;;) {
2209	>	int eh; K ek;
2210	>	if ((eh = e.hash) == h &&
2211	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
2212	>	return e;
2213	>	if (eh < 0) {
2214	>	if (e instanceof ForwardingNode) {
2215	>	tab = ((ForwardingNode<K,V>)e).nextTable;
2216	>	continue outer;
2217	>	}
2218	>	else
2219	>	return e.find(h, k);
2220	>	}
2221	>	if ((e = e.next) == null)
2222	>	return null;
2223	>	}
2224	>	}
2225	>	}
2226		}
2227
2228	<	// inherit Map javadoc
2229	<	public boolean isEmpty() {
2230	<	final Segment[] segments = this.segments;
2231	<	/*
2232	<	* We keep track of per-segment modCounts to avoid ABA
2233	<	* 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;
2228	>	/**
2229	>	* A place-holder node used in computeIfAbsent and compute.
2230	>	*/
2231	>	static final class ReservationNode<K,V> extends Node<K,V> {
2232	>	ReservationNode() {
2233	>	super(RESERVED, null, null);
2234		}
2235	<	// If mcsum happens to be zero, then we know we got a snapshot
2236	<	// before any modifications at all were made.  This is
2237	<	// probably common enough to bother tracking.
2238	<	if (mcsum != 0) {
2239	<	for (int i = 0; i < segments.length; ++i) {
2240	<	if (segments[i].count != 0 ||
2241	<	mc[i] != segments[i].modCount)
2242	<	return false;
2235	>
2236	>	Node<K,V> find(int h, Object k) {
2237	>	return null;
2238	>	}
2239	>	}
2240	>
2241	>	/* ---------------- Table Initialization and Resizing -------------- */
2242	>
2243	>	/**
2244	>	* Returns the stamp bits for resizing a table of size n.
2245	>	* Must be negative when shifted left by RESIZE_STAMP_SHIFT.
2246	>	*/
2247	>	static final int resizeStamp(int n) {
2248	>	return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1));
2249	>	}
2250	>
2251	>	/**
2252	>	* Initializes table, using the size recorded in sizeCtl.
2253	>	*/
2254	>	private final Node<K,V>[] initTable() {
2255	>	Node<K,V>[] tab; int sc;
2256	>	while ((tab = table) == null || tab.length == 0) {
2257	>	if ((sc = sizeCtl) < 0)
2258	>	Thread.yield(); // lost initialization race; just spin
2259	>	else if (U.compareAndSetInt(this, SIZECTL, sc, -1)) {
2260	>	try {
2261	>	if ((tab = table) == null || tab.length == 0) {
2262	>	int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
2263	>	@SuppressWarnings("unchecked")
2264	>	Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
2265	>	table = tab = nt;
2266	>	sc = n - (n >>> 2);
2267	>	}
2268	>	} finally {
2269	>	sizeCtl = sc;
2270	>	}
2271	>	break;
2272		}
2273		}
2274	<	return true;
2274	>	return tab;
2275		}
2276
2277	<	// inherit Map javadoc
2278	<	public int size() {
2279	<	final Segment[] segments = this.segments;
2280	<	long sum = 0;
2281	<	long check = 0;
2282	<	int[] mc = new int[segments.length];
2283	<	// Try a few times to get accurate count. On failure due to
2284	<	// continuous async changes in table, resort to locking.
2285	<	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
2286	<	check = 0;
2287	<	sum = 0;
2288	<	int mcsum = 0;
2289	<	for (int i = 0; i < segments.length; ++i) {
2290	<	sum += segments[i].count;
2291	<	mcsum += mc[i] = segments[i].modCount;
2292	<	}
2293	<	if (mcsum != 0) {
2294	<	for (int i = 0; i < segments.length; ++i) {
2295	<	check += segments[i].count;
2296	<	if (mc[i] != segments[i].modCount) {
2297	<	check = -1; // force retry
2277	>	/**
2278	>	* Adds to count, and if table is too small and not already
2279	>	* resizing, initiates transfer. If already resizing, helps
2280	>	* perform transfer if work is available.  Rechecks occupancy
2281	>	* after a transfer to see if another resize is already needed
2282	>	* because resizings are lagging additions.
2283	>	*
2284	>	* @param x the count to add
2285	>	* @param check if <0, don't check resize, if <= 1 only check if uncontended
2286	>	*/
2287	>	private final void addCount(long x, int check) {
2288	>	CounterCell[] cs; long b, s;
2289	>	if ((cs = counterCells) != null ||
2290	>	!U.compareAndSetLong(this, BASECOUNT, b = baseCount, s = b + x)) {
2291	>	CounterCell c; long v; int m;
2292	>	boolean uncontended = true;
2293	>	if (cs == null || (m = cs.length - 1) < 0 ||
2294	>	(c = cs[ThreadLocalRandom.getProbe() & m]) == null ||
2295	>	!(uncontended =
2296	>	U.compareAndSetLong(c, CELLVALUE, v = c.value, v + x))) {
2297	>	fullAddCount(x, uncontended);
2298	>	return;
2299	>	}
2300	>	if (check <= 1)
2301	>	return;
2302	>	s = sumCount();
2303	>	}
2304	>	if (check >= 0) {
2305	>	Node<K,V>[] tab, nt; int n, sc;
2306	>	while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
2307	>	(n = tab.length) < MAXIMUM_CAPACITY) {
2308	>	int rs = resizeStamp(n) << RESIZE_STAMP_SHIFT;
2309	>	if (sc < 0) {
2310	>	if (sc == rs + MAX_RESIZERS || sc == rs + 1 ||
2311	>	(nt = nextTable) == null || transferIndex <= 0)
2312		break;
2313	+	if (U.compareAndSetInt(this, SIZECTL, sc, sc + 1))
2314	+	transfer(tab, nt);
2315	+	}
2316	+	else if (U.compareAndSetInt(this, SIZECTL, sc, rs + 2))
2317	+	transfer(tab, null);
2318	+	s = sumCount();
2319	+	}
2320	+	}
2321	+	}
2322	+
2323	+	/**
2324	+	* Helps transfer if a resize is in progress.
2325	+	*/
2326	+	final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) {
2327	+	Node<K,V>[] nextTab; int sc;
2328	+	if (tab != null && (f instanceof ForwardingNode) &&
2329	+	(nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) {
2330	+	int rs = resizeStamp(tab.length) << RESIZE_STAMP_SHIFT;
2331	+	while (nextTab == nextTable && table == tab &&
2332	+	(sc = sizeCtl) < 0) {
2333	+	if (sc == rs + MAX_RESIZERS || sc == rs + 1 ||
2334	+	transferIndex <= 0)
2335	+	break;
2336	+	if (U.compareAndSetInt(this, SIZECTL, sc, sc + 1)) {
2337	+	transfer(tab, nextTab);
2338	+	break;
2339	+	}
2340	+	}
2341	+	return nextTab;
2342	+	}
2343	+	return table;
2344	+	}
2345	+
2346	+	/**
2347	+	* Tries to presize table to accommodate the given number of elements.
2348	+	*
2349	+	* @param size number of elements (doesn't need to be perfectly accurate)
2350	+	*/
2351	+	private final void tryPresize(int size) {
2352	+	int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
2353	+	tableSizeFor(size + (size >>> 1) + 1);
2354	+	int sc;
2355	+	while ((sc = sizeCtl) >= 0) {
2356	+	Node<K,V>[] tab = table; int n;
2357	+	if (tab == null || (n = tab.length) == 0) {
2358	+	n = (sc > c) ? sc : c;
2359	+	if (U.compareAndSetInt(this, SIZECTL, sc, -1)) {
2360	+	try {
2361	+	if (table == tab) {
2362	+	@SuppressWarnings("unchecked")
2363	+	Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
2364	+	table = nt;
2365	+	sc = n - (n >>> 2);
2366	+	}
2367	+	} finally {
2368	+	sizeCtl = sc;
2369		}
2370		}
2371		}
2372	<	if (check == sum)
2372	>	else if (c <= sc || n >= MAXIMUM_CAPACITY)
2373		break;
2374	+	else if (tab == table) {
2375	+	int rs = resizeStamp(n);
2376	+	if (U.compareAndSetInt(this, SIZECTL, sc,
2377	+	(rs << RESIZE_STAMP_SHIFT) + 2))
2378	+	transfer(tab, null);
2379	+	}
2380		}
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;
2381		}
2382
2383	+	/**
2384	+	* Moves and/or copies the nodes in each bin to new table. See
2385	+	* above for explanation.
2386	+	*/
2387	+	private final void transfer(Node<K,V>[] tab, Node<K,V>[] nextTab) {
2388	+	int n = tab.length, stride;
2389	+	if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
2390	+	stride = MIN_TRANSFER_STRIDE; // subdivide range
2391	+	if (nextTab == null) {            // initiating
2392	+	try {
2393	+	@SuppressWarnings("unchecked")
2394	+	Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n << 1];
2395	+	nextTab = nt;
2396	+	} catch (Throwable ex) {      // try to cope with OOME
2397	+	sizeCtl = Integer.MAX_VALUE;
2398	+	return;
2399	+	}
2400	+	nextTable = nextTab;
2401	+	transferIndex = n;
2402	+	}
2403	+	int nextn = nextTab.length;
2404	+	ForwardingNode<K,V> fwd = new ForwardingNode<K,V>(nextTab);
2405	+	boolean advance = true;
2406	+	boolean finishing = false; // to ensure sweep before committing nextTab
2407	+	for (int i = 0, bound = 0;;) {
2408	+	Node<K,V> f; int fh;
2409	+	while (advance) {
2410	+	int nextIndex, nextBound;
2411	+	if (--i >= bound || finishing)
2412	+	advance = false;
2413	+	else if ((nextIndex = transferIndex) <= 0) {
2414	+	i = -1;
2415	+	advance = false;
2416	+	}
2417	+	else if (U.compareAndSetInt
2418	+	(this, TRANSFERINDEX, nextIndex,
2419	+	nextBound = (nextIndex > stride ?
2420	+	nextIndex - stride : 0))) {
2421	+	bound = nextBound;
2422	+	i = nextIndex - 1;
2423	+	advance = false;
2424	+	}
2425	+	}
2426	+	if (i < 0 || i >= n || i + n >= nextn) {
2427	+	int sc;
2428	+	if (finishing) {
2429	+	nextTable = null;
2430	+	table = nextTab;
2431	+	sizeCtl = (n << 1) - (n >>> 1);
2432	+	return;
2433	+	}
2434	+	if (U.compareAndSetInt(this, SIZECTL, sc = sizeCtl, sc - 1)) {
2435	+	if ((sc - 2) != resizeStamp(n) << RESIZE_STAMP_SHIFT)
2436	+	return;
2437	+	finishing = advance = true;
2438	+	i = n; // recheck before commit
2439	+	}
2440	+	}
2441	+	else if ((f = tabAt(tab, i)) == null)
2442	+	advance = casTabAt(tab, i, null, fwd);
2443	+	else if ((fh = f.hash) == MOVED)
2444	+	advance = true; // already processed
2445	+	else {
2446	+	synchronized (f) {
2447	+	if (tabAt(tab, i) == f) {
2448	+	Node<K,V> ln, hn;
2449	+	if (fh >= 0) {
2450	+	int runBit = fh & n;
2451	+	Node<K,V> lastRun = f;
2452	+	for (Node<K,V> p = f.next; p != null; p = p.next) {
2453	+	int b = p.hash & n;
2454	+	if (b != runBit) {
2455	+	runBit = b;
2456	+	lastRun = p;
2457	+	}
2458	+	}
2459	+	if (runBit == 0) {
2460	+	ln = lastRun;
2461	+	hn = null;
2462	+	}
2463	+	else {
2464	+	hn = lastRun;
2465	+	ln = null;
2466	+	}
2467	+	for (Node<K,V> p = f; p != lastRun; p = p.next) {
2468	+	int ph = p.hash; K pk = p.key; V pv = p.val;
2469	+	if ((ph & n) == 0)
2470	+	ln = new Node<K,V>(ph, pk, pv, ln);
2471	+	else
2472	+	hn = new Node<K,V>(ph, pk, pv, hn);
2473	+	}
2474	+	setTabAt(nextTab, i, ln);
2475	+	setTabAt(nextTab, i + n, hn);
2476	+	setTabAt(tab, i, fwd);
2477	+	advance = true;
2478	+	}
2479	+	else if (f instanceof TreeBin) {
2480	+	TreeBin<K,V> t = (TreeBin<K,V>)f;
2481	+	TreeNode<K,V> lo = null, loTail = null;
2482	+	TreeNode<K,V> hi = null, hiTail = null;
2483	+	int lc = 0, hc = 0;
2484	+	for (Node<K,V> e = t.first; e != null; e = e.next) {
2485	+	int h = e.hash;
2486	+	TreeNode<K,V> p = new TreeNode<K,V>
2487	+	(h, e.key, e.val, null, null);
2488	+	if ((h & n) == 0) {
2489	+	if ((p.prev = loTail) == null)
2490	+	lo = p;
2491	+	else
2492	+	loTail.next = p;
2493	+	loTail = p;
2494	+	++lc;
2495	+	}
2496	+	else {
2497	+	if ((p.prev = hiTail) == null)
2498	+	hi = p;
2499	+	else
2500	+	hiTail.next = p;
2501	+	hiTail = p;
2502	+	++hc;
2503	+	}
2504	+	}
2505	+	ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) :
2506	+	(hc != 0) ? new TreeBin<K,V>(lo) : t;
2507	+	hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
2508	+	(lc != 0) ? new TreeBin<K,V>(hi) : t;
2509	+	setTabAt(nextTab, i, ln);
2510	+	setTabAt(nextTab, i + n, hn);
2511	+	setTabAt(tab, i, fwd);
2512	+	advance = true;
2513	+	}
2514	+	else if (f instanceof ReservationNode)
2515	+	throw new IllegalStateException("Recursive update");
2516	+	}
2517	+	}
2518	+	}
2519	+	}
2520	+	}
2521	+
2522	+	/* ---------------- Counter support -------------- */
2523
2524		/**
2525	<	* Returns the value to which the specified key is mapped in this table.
2526	<	*
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>.
2525	>	* A padded cell for distributing counts.  Adapted from LongAdder
2526	>	* and Striped64.  See their internal docs for explanation.
2527		*/
2528	<	public V get(Object key) {
2529	<	int hash = hash(key); // throws NullPointerException if key null
2530	<	return segmentFor(hash).get(key, hash);
2528	>	@jdk.internal.vm.annotation.Contended static final class CounterCell {
2529	>	volatile long value;
2530	>	CounterCell(long x) { value = x; }
2531	>	}
2532	>
2533	>	final long sumCount() {
2534	>	CounterCell[] cs = counterCells;
2535	>	long sum = baseCount;
2536	>	if (cs != null) {
2537	>	for (CounterCell c : cs)
2538	>	if (c != null)
2539	>	sum += c.value;
2540	>	}
2541	>	return sum;
2542		}
2543
2544	+	// See LongAdder version for explanation
2545	+	private final void fullAddCount(long x, boolean wasUncontended) {
2546	+	int h;
2547	+	if ((h = ThreadLocalRandom.getProbe()) == 0) {
2548	+	ThreadLocalRandom.localInit();      // force initialization
2549	+	h = ThreadLocalRandom.getProbe();
2550	+	wasUncontended = true;
2551	+	}
2552	+	boolean collide = false;                // True if last slot nonempty
2553	+	for (;;) {
2554	+	CounterCell[] cs; CounterCell c; int n; long v;
2555	+	if ((cs = counterCells) != null && (n = cs.length) > 0) {
2556	+	if ((c = cs[(n - 1) & h]) == null) {
2557	+	if (cellsBusy == 0) {            // Try to attach new Cell
2558	+	CounterCell r = new CounterCell(x); // Optimistic create
2559	+	if (cellsBusy == 0 &&
2560	+	U.compareAndSetInt(this, CELLSBUSY, 0, 1)) {
2561	+	boolean created = false;
2562	+	try {               // Recheck under lock
2563	+	CounterCell[] rs; int m, j;
2564	+	if ((rs = counterCells) != null &&
2565	+	(m = rs.length) > 0 &&
2566	+	rs[j = (m - 1) & h] == null) {
2567	+	rs[j] = r;
2568	+	created = true;
2569	+	}
2570	+	} finally {
2571	+	cellsBusy = 0;
2572	+	}
2573	+	if (created)
2574	+	break;
2575	+	continue;           // Slot is now non-empty
2576	+	}
2577	+	}
2578	+	collide = false;
2579	+	}
2580	+	else if (!wasUncontended)       // CAS already known to fail
2581	+	wasUncontended = true;      // Continue after rehash
2582	+	else if (U.compareAndSetLong(c, CELLVALUE, v = c.value, v + x))
2583	+	break;
2584	+	else if (counterCells != cs || n >= NCPU)
2585	+	collide = false;            // At max size or stale
2586	+	else if (!collide)
2587	+	collide = true;
2588	+	else if (cellsBusy == 0 &&
2589	+	U.compareAndSetInt(this, CELLSBUSY, 0, 1)) {
2590	+	try {
2591	+	if (counterCells == cs) // Expand table unless stale
2592	+	counterCells = Arrays.copyOf(cs, n << 1);
2593	+	} finally {
2594	+	cellsBusy = 0;
2595	+	}
2596	+	collide = false;
2597	+	continue;                   // Retry with expanded table
2598	+	}
2599	+	h = ThreadLocalRandom.advanceProbe(h);
2600	+	}
2601	+	else if (cellsBusy == 0 && counterCells == cs &&
2602	+	U.compareAndSetInt(this, CELLSBUSY, 0, 1)) {
2603	+	boolean init = false;
2604	+	try {                           // Initialize table
2605	+	if (counterCells == cs) {
2606	+	CounterCell[] rs = new CounterCell[2];
2607	+	rs[h & 1] = new CounterCell(x);
2608	+	counterCells = rs;
2609	+	init = true;
2610	+	}
2611	+	} finally {
2612	+	cellsBusy = 0;
2613	+	}
2614	+	if (init)
2615	+	break;
2616	+	}
2617	+	else if (U.compareAndSetLong(this, BASECOUNT, v = baseCount, v + x))
2618	+	break;                          // Fall back on using base
2619	+	}
2620	+	}
2621	+
2622	+	/* ---------------- Conversion from/to TreeBins -------------- */
2623	+
2624		/**
2625	<	* Tests if the specified object is a key in this table.
2626	<	*
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>.
2625	>	* Replaces all linked nodes in bin at given index unless table is
2626	>	* too small, in which case resizes instead.
2627		*/
2628	<	public boolean containsKey(Object key) {
2629	<	int hash = hash(key); // throws NullPointerException if key null
2630	<	return segmentFor(hash).containsKey(key, hash);
2628	>	private final void treeifyBin(Node<K,V>[] tab, int index) {
2629	>	Node<K,V> b; int n;
2630	>	if (tab != null) {
2631	>	if ((n = tab.length) < MIN_TREEIFY_CAPACITY)
2632	>	tryPresize(n << 1);
2633	>	else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
2634	>	synchronized (b) {
2635	>	if (tabAt(tab, index) == b) {
2636	>	TreeNode<K,V> hd = null, tl = null;
2637	>	for (Node<K,V> e = b; e != null; e = e.next) {
2638	>	TreeNode<K,V> p =
2639	>	new TreeNode<K,V>(e.hash, e.key, e.val,
2640	>	null, null);
2641	>	if ((p.prev = tl) == null)
2642	>	hd = p;
2643	>	else
2644	>	tl.next = p;
2645	>	tl = p;
2646	>	}
2647	>	setTabAt(tab, index, new TreeBin<K,V>(hd));
2648	>	}
2649	>	}
2650	>	}
2651	>	}
2652		}
2653
2654		/**
2655	<	* 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>.
2655	>	* Returns a list of non-TreeNodes replacing those in given list.
2656		*/
2657	<	public boolean containsValue(Object value) {
2658	<	if (value == null)
2659	<	throw new NullPointerException();
2660	<
2661	<	// See explanation of modCount use above
2657	>	static <K,V> Node<K,V> untreeify(Node<K,V> b) {
2658	>	Node<K,V> hd = null, tl = null;
2659	>	for (Node<K,V> q = b; q != null; q = q.next) {
2660	>	Node<K,V> p = new Node<K,V>(q.hash, q.key, q.val);
2661	>	if (tl == null)
2662	>	hd = p;
2663	>	else
2664	>	tl.next = p;
2665	>	tl = p;
2666	>	}
2667	>	return hd;
2668	>	}
2669
2670	<	final Segment[] segments = this.segments;
768	<	int[] mc = new int[segments.length];
2670	>	/* ---------------- TreeNodes -------------- */
2671
2672	<	// Try a few times without locking
2673	<	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
2674	<	int sum = 0;
2675	<	int mcsum = 0;
2676	<	for (int i = 0; i < segments.length; ++i) {
2677	<	int c = segments[i].count;
2678	<	mcsum += mc[i] = segments[i].modCount;
2679	<	if (segments[i].containsValue(value))
2680	<	return true;
2672	>	/**
2673	>	* Nodes for use in TreeBins.
2674	>	*/
2675	>	static final class TreeNode<K,V> extends Node<K,V> {
2676	>	TreeNode<K,V> parent;  // red-black tree links
2677	>	TreeNode<K,V> left;
2678	>	TreeNode<K,V> right;
2679	>	TreeNode<K,V> prev;    // needed to unlink next upon deletion
2680	>	boolean red;
2681	>
2682	>	TreeNode(int hash, K key, V val, Node<K,V> next,
2683	>	TreeNode<K,V> parent) {
2684	>	super(hash, key, val, next);
2685	>	this.parent = parent;
2686	>	}
2687	>
2688	>	Node<K,V> find(int h, Object k) {
2689	>	return findTreeNode(h, k, null);
2690	>	}
2691	>
2692	>	/**
2693	>	* Returns the TreeNode (or null if not found) for the given key
2694	>	* starting at given root.
2695	>	*/
2696	>	final TreeNode<K,V> findTreeNode(int h, Object k, Class<?> kc) {
2697	>	if (k != null) {
2698	>	TreeNode<K,V> p = this;
2699	>	do {
2700	>	int ph, dir; K pk; TreeNode<K,V> q;
2701	>	TreeNode<K,V> pl = p.left, pr = p.right;
2702	>	if ((ph = p.hash) > h)
2703	>	p = pl;
2704	>	else if (ph < h)
2705	>	p = pr;
2706	>	else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2707	>	return p;
2708	>	else if (pl == null)
2709	>	p = pr;
2710	>	else if (pr == null)
2711	>	p = pl;
2712	>	else if ((kc != null ||
2713	>	(kc = comparableClassFor(k)) != null) &&
2714	>	(dir = compareComparables(kc, k, pk)) != 0)
2715	>	p = (dir < 0) ? pl : pr;
2716	>	else if ((q = pr.findTreeNode(h, k, kc)) != null)
2717	>	return q;
2718	>	else
2719	>	p = pl;
2720	>	} while (p != null);
2721		}
2722	<	boolean cleanSweep = true;
2723	<	if (mcsum != 0) {
2724	<	for (int i = 0; i < segments.length; ++i) {
2725	<	int c = segments[i].count;
2726	<	if (mc[i] != segments[i].modCount) {
2727	<	cleanSweep = false;
2728	<	break;
2722	>	return null;
2723	>	}
2724	>	}
2725	>
2726	>	/* ---------------- TreeBins -------------- */
2727	>
2728	>	/**
2729	>	* TreeNodes used at the heads of bins. TreeBins do not hold user
2730	>	* keys or values, but instead point to list of TreeNodes and
2731	>	* their root. They also maintain a parasitic read-write lock
2732	>	* forcing writers (who hold bin lock) to wait for readers (who do
2733	>	* not) to complete before tree restructuring operations.
2734	>	*/
2735	>	static final class TreeBin<K,V> extends Node<K,V> {
2736	>	TreeNode<K,V> root;
2737	>	volatile TreeNode<K,V> first;
2738	>	volatile Thread waiter;
2739	>	volatile int lockState;
2740	>	// values for lockState
2741	>	static final int WRITER = 1; // set while holding write lock
2742	>	static final int WAITER = 2; // set when waiting for write lock
2743	>	static final int READER = 4; // increment value for setting read lock
2744	>
2745	>	/**
2746	>	* Tie-breaking utility for ordering insertions when equal
2747	>	* hashCodes and non-comparable. We don't require a total
2748	>	* order, just a consistent insertion rule to maintain
2749	>	* equivalence across rebalancings. Tie-breaking further than
2750	>	* necessary simplifies testing a bit.
2751	>	*/
2752	>	static int tieBreakOrder(Object a, Object b) {
2753	>	int d;
2754	>	if (a == null || b == null ||
2755	>	(d = a.getClass().getName().
2756	>	compareTo(b.getClass().getName())) == 0)
2757	>	d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
2758	>	-1 : 1);
2759	>	return d;
2760	>	}
2761	>
2762	>	/**
2763	>	* Creates bin with initial set of nodes headed by b.
2764	>	*/
2765	>	TreeBin(TreeNode<K,V> b) {
2766	>	super(TREEBIN, null, null);
2767	>	this.first = b;
2768	>	TreeNode<K,V> r = null;
2769	>	for (TreeNode<K,V> x = b, next; x != null; x = next) {
2770	>	next = (TreeNode<K,V>)x.next;
2771	>	x.left = x.right = null;
2772	>	if (r == null) {
2773	>	x.parent = null;
2774	>	x.red = false;
2775	>	r = x;
2776	>	}
2777	>	else {
2778	>	K k = x.key;
2779	>	int h = x.hash;
2780	>	Class<?> kc = null;
2781	>	for (TreeNode<K,V> p = r;;) {
2782	>	int dir, ph;
2783	>	K pk = p.key;
2784	>	if ((ph = p.hash) > h)
2785	>	dir = -1;
2786	>	else if (ph < h)
2787	>	dir = 1;
2788	>	else if ((kc == null &&
2789	>	(kc = comparableClassFor(k)) == null) ||
2790	>	(dir = compareComparables(kc, k, pk)) == 0)
2791	>	dir = tieBreakOrder(k, pk);
2792	>	TreeNode<K,V> xp = p;
2793	>	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2794	>	x.parent = xp;
2795	>	if (dir <= 0)
2796	>	xp.left = x;
2797	>	else
2798	>	xp.right = x;
2799	>	r = balanceInsertion(r, x);
2800	>	break;
2801	>	}
2802		}
2803		}
2804		}
2805	<	if (cleanSweep)
2806	<	return false;
2805	>	this.root = r;
2806	>	assert checkInvariants(root);
2807	>	}
2808	>
2809	>	/**
2810	>	* Acquires write lock for tree restructuring.
2811	>	*/
2812	>	private final void lockRoot() {
2813	>	if (!U.compareAndSetInt(this, LOCKSTATE, 0, WRITER))
2814	>	contendedLock(); // offload to separate method
2815	>	}
2816	>
2817	>	/**
2818	>	* Releases write lock for tree restructuring.
2819	>	*/
2820	>	private final void unlockRoot() {
2821	>	lockState = 0;
2822		}
2823	<	// Resort to locking all segments
2824	<	for (int i = 0; i < segments.length; ++i)
2825	<	segments[i].lock();
2826	<	boolean found = false;
2827	<	try {
2828	<	for (int i = 0; i < segments.length; ++i) {
2829	<	if (segments[i].containsValue(value)) {
2830	<	found = true;
2823	>
2824	>	/**
2825	>	* Possibly blocks awaiting root lock.
2826	>	*/
2827	>	private final void contendedLock() {
2828	>	boolean waiting = false;
2829	>	for (int s;;) {
2830	>	if (((s = lockState) & ~WAITER) == 0) {
2831	>	if (U.compareAndSetInt(this, LOCKSTATE, s, WRITER)) {
2832	>	if (waiting)
2833	>	waiter = null;
2834	>	return;
2835	>	}
2836	>	}
2837	>	else if ((s & WAITER) == 0) {
2838	>	if (U.compareAndSetInt(this, LOCKSTATE, s, s | WAITER)) {
2839	>	waiting = true;
2840	>	waiter = Thread.currentThread();
2841	>	}
2842	>	}
2843	>	else if (waiting)
2844	>	LockSupport.park(this);
2845	>	}
2846	>	}
2847	>
2848	>	/**
2849	>	* Returns matching node or null if none. Tries to search
2850	>	* using tree comparisons from root, but continues linear
2851	>	* search when lock not available.
2852	>	*/
2853	>	final Node<K,V> find(int h, Object k) {
2854	>	if (k != null) {
2855	>	for (Node<K,V> e = first; e != null; ) {
2856	>	int s; K ek;
2857	>	if (((s = lockState) & (WAITER|WRITER)) != 0) {
2858	>	if (e.hash == h &&
2859	>	((ek = e.key) == k || (ek != null && k.equals(ek))))
2860	>	return e;
2861	>	e = e.next;
2862	>	}
2863	>	else if (U.compareAndSetInt(this, LOCKSTATE, s,
2864	>	s + READER)) {
2865	>	TreeNode<K,V> r, p;
2866	>	try {
2867	>	p = ((r = root) == null ? null :
2868	>	r.findTreeNode(h, k, null));
2869	>	} finally {
2870	>	Thread w;
2871	>	if (U.getAndAddInt(this, LOCKSTATE, -READER) ==
2872	>	(READER|WAITER) && (w = waiter) != null)
2873	>	LockSupport.unpark(w);
2874	>	}
2875	>	return p;
2876	>	}
2877	>	}
2878	>	}
2879	>	return null;
2880	>	}
2881	>
2882	>	/**
2883	>	* Finds or adds a node.
2884	>	* @return null if added
2885	>	*/
2886	>	final TreeNode<K,V> putTreeVal(int h, K k, V v) {
2887	>	Class<?> kc = null;
2888	>	boolean searched = false;
2889	>	for (TreeNode<K,V> p = root;;) {
2890	>	int dir, ph; K pk;
2891	>	if (p == null) {
2892	>	first = root = new TreeNode<K,V>(h, k, v, null, null);
2893		break;
2894		}
2895	+	else if ((ph = p.hash) > h)
2896	+	dir = -1;
2897	+	else if (ph < h)
2898	+	dir = 1;
2899	+	else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2900	+	return p;
2901	+	else if ((kc == null &&
2902	+	(kc = comparableClassFor(k)) == null) ||
2903	+	(dir = compareComparables(kc, k, pk)) == 0) {
2904	+	if (!searched) {
2905	+	TreeNode<K,V> q, ch;
2906	+	searched = true;
2907	+	if (((ch = p.left) != null &&
2908	+	(q = ch.findTreeNode(h, k, kc)) != null) ||
2909	+	((ch = p.right) != null &&
2910	+	(q = ch.findTreeNode(h, k, kc)) != null))
2911	+	return q;
2912	+	}
2913	+	dir = tieBreakOrder(k, pk);
2914	+	}
2915	+
2916	+	TreeNode<K,V> xp = p;
2917	+	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2918	+	TreeNode<K,V> x, f = first;
2919	+	first = x = new TreeNode<K,V>(h, k, v, f, xp);
2920	+	if (f != null)
2921	+	f.prev = x;
2922	+	if (dir <= 0)
2923	+	xp.left = x;
2924	+	else
2925	+	xp.right = x;
2926	+	if (!xp.red)
2927	+	x.red = true;
2928	+	else {
2929	+	lockRoot();
2930	+	try {
2931	+	root = balanceInsertion(root, x);
2932	+	} finally {
2933	+	unlockRoot();
2934	+	}
2935	+	}
2936	+	break;
2937	+	}
2938	+	}
2939	+	assert checkInvariants(root);
2940	+	return null;
2941	+	}
2942	+
2943	+	/**
2944	+	* Removes the given node, that must be present before this
2945	+	* call.  This is messier than typical red-black deletion code
2946	+	* because we cannot swap the contents of an interior node
2947	+	* with a leaf successor that is pinned by "next" pointers
2948	+	* that are accessible independently of lock. So instead we
2949	+	* swap the tree linkages.
2950	+	*
2951	+	* @return true if now too small, so should be untreeified
2952	+	*/
2953	+	final boolean removeTreeNode(TreeNode<K,V> p) {
2954	+	TreeNode<K,V> next = (TreeNode<K,V>)p.next;
2955	+	TreeNode<K,V> pred = p.prev;  // unlink traversal pointers
2956	+	TreeNode<K,V> r, rl;
2957	+	if (pred == null)
2958	+	first = next;
2959	+	else
2960	+	pred.next = next;
2961	+	if (next != null)
2962	+	next.prev = pred;
2963	+	if (first == null) {
2964	+	root = null;
2965	+	return true;
2966	+	}
2967	+	if ((r = root) == null || r.right == null || // too small
2968	+	(rl = r.left) == null || rl.left == null)
2969	+	return true;
2970	+	lockRoot();
2971	+	try {
2972	+	TreeNode<K,V> replacement;
2973	+	TreeNode<K,V> pl = p.left;
2974	+	TreeNode<K,V> pr = p.right;
2975	+	if (pl != null && pr != null) {
2976	+	TreeNode<K,V> s = pr, sl;
2977	+	while ((sl = s.left) != null) // find successor
2978	+	s = sl;
2979	+	boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2980	+	TreeNode<K,V> sr = s.right;
2981	+	TreeNode<K,V> pp = p.parent;
2982	+	if (s == pr) { // p was s's direct parent
2983	+	p.parent = s;
2984	+	s.right = p;
2985	+	}
2986	+	else {
2987	+	TreeNode<K,V> sp = s.parent;
2988	+	if ((p.parent = sp) != null) {
2989	+	if (s == sp.left)
2990	+	sp.left = p;
2991	+	else
2992	+	sp.right = p;
2993	+	}
2994	+	if ((s.right = pr) != null)
2995	+	pr.parent = s;
2996	+	}
2997	+	p.left = null;
2998	+	if ((p.right = sr) != null)
2999	+	sr.parent = p;
3000	+	if ((s.left = pl) != null)
3001	+	pl.parent = s;
3002	+	if ((s.parent = pp) == null)
3003	+	r = s;
3004	+	else if (p == pp.left)
3005	+	pp.left = s;
3006	+	else
3007	+	pp.right = s;
3008	+	if (sr != null)
3009	+	replacement = sr;
3010	+	else
3011	+	replacement = p;
3012	+	}
3013	+	else if (pl != null)
3014	+	replacement = pl;
3015	+	else if (pr != null)
3016	+	replacement = pr;
3017	+	else
3018	+	replacement = p;
3019	+	if (replacement != p) {
3020	+	TreeNode<K,V> pp = replacement.parent = p.parent;
3021	+	if (pp == null)
3022	+	r = replacement;
3023	+	else if (p == pp.left)
3024	+	pp.left = replacement;
3025	+	else
3026	+	pp.right = replacement;
3027	+	p.left = p.right = p.parent = null;
3028	+	}
3029	+
3030	+	root = (p.red) ? r : balanceDeletion(r, replacement);
3031	+
3032	+	if (p == replacement) {  // detach pointers
3033	+	TreeNode<K,V> pp;
3034	+	if ((pp = p.parent) != null) {
3035	+	if (p == pp.left)
3036	+	pp.left = null;
3037	+	else if (p == pp.right)
3038	+	pp.right = null;
3039	+	p.parent = null;
3040	+	}
3041	+	}
3042	+	} finally {
3043	+	unlockRoot();
3044	+	}
3045	+	assert checkInvariants(root);
3046	+	return false;
3047	+	}
3048	+
3049	+	/* ------------------------------------------------------------ */
3050	+	// Red-black tree methods, all adapted from CLR
3051	+
3052	+	static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
3053	+	TreeNode<K,V> p) {
3054	+	TreeNode<K,V> r, pp, rl;
3055	+	if (p != null && (r = p.right) != null) {
3056	+	if ((rl = p.right = r.left) != null)
3057	+	rl.parent = p;
3058	+	if ((pp = r.parent = p.parent) == null)
3059	+	(root = r).red = false;
3060	+	else if (pp.left == p)
3061	+	pp.left = r;
3062	+	else
3063	+	pp.right = r;
3064	+	r.left = p;
3065	+	p.parent = r;
3066	+	}
3067	+	return root;
3068	+	}
3069	+
3070	+	static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
3071	+	TreeNode<K,V> p) {
3072	+	TreeNode<K,V> l, pp, lr;
3073	+	if (p != null && (l = p.left) != null) {
3074	+	if ((lr = p.left = l.right) != null)
3075	+	lr.parent = p;
3076	+	if ((pp = l.parent = p.parent) == null)
3077	+	(root = l).red = false;
3078	+	else if (pp.right == p)
3079	+	pp.right = l;
3080	+	else
3081	+	pp.left = l;
3082	+	l.right = p;
3083	+	p.parent = l;
3084	+	}
3085	+	return root;
3086	+	}
3087	+
3088	+	static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
3089	+	TreeNode<K,V> x) {
3090	+	x.red = true;
3091	+	for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
3092	+	if ((xp = x.parent) == null) {
3093	+	x.red = false;
3094	+	return x;
3095	+	}
3096	+	else if (!xp.red || (xpp = xp.parent) == null)
3097	+	return root;
3098	+	if (xp == (xppl = xpp.left)) {
3099	+	if ((xppr = xpp.right) != null && xppr.red) {
3100	+	xppr.red = false;
3101	+	xp.red = false;
3102	+	xpp.red = true;
3103	+	x = xpp;
3104	+	}
3105	+	else {
3106	+	if (x == xp.right) {
3107	+	root = rotateLeft(root, x = xp);
3108	+	xpp = (xp = x.parent) == null ? null : xp.parent;
3109	+	}
3110	+	if (xp != null) {
3111	+	xp.red = false;
3112	+	if (xpp != null) {
3113	+	xpp.red = true;
3114	+	root = rotateRight(root, xpp);
3115	+	}
3116	+	}
3117	+	}
3118	+	}
3119	+	else {
3120	+	if (xppl != null && xppl.red) {
3121	+	xppl.red = false;
3122	+	xp.red = false;
3123	+	xpp.red = true;
3124	+	x = xpp;
3125	+	}
3126	+	else {
3127	+	if (x == xp.left) {
3128	+	root = rotateRight(root, x = xp);
3129	+	xpp = (xp = x.parent) == null ? null : xp.parent;
3130	+	}
3131	+	if (xp != null) {
3132	+	xp.red = false;
3133	+	if (xpp != null) {
3134	+	xpp.red = true;
3135	+	root = rotateLeft(root, xpp);
3136	+	}
3137	+	}
3138	+	}
3139	+	}
3140	+	}
3141	+	}
3142	+
3143	+	static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
3144	+	TreeNode<K,V> x) {
3145	+	for (TreeNode<K,V> xp, xpl, xpr;;) {
3146	+	if (x == null || x == root)
3147	+	return root;
3148	+	else if ((xp = x.parent) == null) {
3149	+	x.red = false;
3150	+	return x;
3151	+	}
3152	+	else if (x.red) {
3153	+	x.red = false;
3154	+	return root;
3155	+	}
3156	+	else if ((xpl = xp.left) == x) {
3157	+	if ((xpr = xp.right) != null && xpr.red) {
3158	+	xpr.red = false;
3159	+	xp.red = true;
3160	+	root = rotateLeft(root, xp);
3161	+	xpr = (xp = x.parent) == null ? null : xp.right;
3162	+	}
3163	+	if (xpr == null)
3164	+	x = xp;
3165	+	else {
3166	+	TreeNode<K,V> sl = xpr.left, sr = xpr.right;
3167	+	if ((sr == null || !sr.red) &&
3168	+	(sl == null || !sl.red)) {
3169	+	xpr.red = true;
3170	+	x = xp;
3171	+	}
3172	+	else {
3173	+	if (sr == null || !sr.red) {
3174	+	if (sl != null)
3175	+	sl.red = false;
3176	+	xpr.red = true;
3177	+	root = rotateRight(root, xpr);
3178	+	xpr = (xp = x.parent) == null ?
3179	+	null : xp.right;
3180	+	}
3181	+	if (xpr != null) {
3182	+	xpr.red = (xp == null) ? false : xp.red;
3183	+	if ((sr = xpr.right) != null)
3184	+	sr.red = false;
3185	+	}
3186	+	if (xp != null) {
3187	+	xp.red = false;
3188	+	root = rotateLeft(root, xp);
3189	+	}
3190	+	x = root;
3191	+	}
3192	+	}
3193	+	}
3194	+	else { // symmetric
3195	+	if (xpl != null && xpl.red) {
3196	+	xpl.red = false;
3197	+	xp.red = true;
3198	+	root = rotateRight(root, xp);
3199	+	xpl = (xp = x.parent) == null ? null : xp.left;
3200	+	}
3201	+	if (xpl == null)
3202	+	x = xp;
3203	+	else {
3204	+	TreeNode<K,V> sl = xpl.left, sr = xpl.right;
3205	+	if ((sl == null || !sl.red) &&
3206	+	(sr == null || !sr.red)) {
3207	+	xpl.red = true;
3208	+	x = xp;
3209	+	}
3210	+	else {
3211	+	if (sl == null || !sl.red) {
3212	+	if (sr != null)
3213	+	sr.red = false;
3214	+	xpl.red = true;
3215	+	root = rotateLeft(root, xpl);
3216	+	xpl = (xp = x.parent) == null ?
3217	+	null : xp.left;
3218	+	}
3219	+	if (xpl != null) {
3220	+	xpl.red = (xp == null) ? false : xp.red;
3221	+	if ((sl = xpl.left) != null)
3222	+	sl.red = false;
3223	+	}
3224	+	if (xp != null) {
3225	+	xp.red = false;
3226	+	root = rotateRight(root, xp);
3227	+	}
3228	+	x = root;
3229	+	}
3230	+	}
3231	+	}
3232		}
804	–	} finally {
805	–	for (int i = 0; i < segments.length; ++i)
806	–	segments[i].unlock();
3233		}
3234	<	return found;
3234	>
3235	>	/**
3236	>	* Checks invariants recursively for the tree of Nodes rooted at t.
3237	>	*/
3238	>	static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
3239	>	TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
3240	>	tb = t.prev, tn = (TreeNode<K,V>)t.next;
3241	>	if (tb != null && tb.next != t)
3242	>	return false;
3243	>	if (tn != null && tn.prev != t)
3244	>	return false;
3245	>	if (tp != null && t != tp.left && t != tp.right)
3246	>	return false;
3247	>	if (tl != null && (tl.parent != t || tl.hash > t.hash))
3248	>	return false;
3249	>	if (tr != null && (tr.parent != t || tr.hash < t.hash))
3250	>	return false;
3251	>	if (t.red && tl != null && tl.red && tr != null && tr.red)
3252	>	return false;
3253	>	if (tl != null && !checkInvariants(tl))
3254	>	return false;
3255	>	if (tr != null && !checkInvariants(tr))
3256	>	return false;
3257	>	return true;
3258	>	}
3259	>
3260	>	private static final long LOCKSTATE
3261	>	= U.objectFieldOffset(TreeBin.class, "lockState");
3262		}
3263
3264	+	/* ----------------Table Traversal -------------- */
3265	+
3266		/**
3267	<	* Legacy method testing if some key maps into the specified value
3268	<	* in this table.  This method is identical in functionality to
3269	<	* {@link #containsValue}, and  exists solely to ensure
3270	<	* full compatibility with class {@link java.util.Hashtable},
3271	<	* which supported this method prior to introduction of the
3272	<	* Java Collections framework.
3267	>	* Records the table, its length, and current traversal index for a
3268	>	* traverser that must process a region of a forwarded table before
3269	>	* proceeding with current table.
3270	>	*/
3271	>	static final class TableStack<K,V> {
3272	>	int length;
3273	>	int index;
3274	>	Node<K,V>[] tab;
3275	>	TableStack<K,V> next;
3276	>	}
3277
3278	<	* @param      value   a value to search for.
3279	<	* @return     <tt>true</tt> if and only if some key maps to the
3280	<	*             <tt>value</tt> argument in this table as
3281	<	*             determined by the <tt>equals</tt> method;
3282	<	*             <tt>false</tt> otherwise.
3283	<	* @throws  NullPointerException  if the value is <tt>null</tt>.
3278	>	/**
3279	>	* Encapsulates traversal for methods such as containsValue; also
3280	>	* serves as a base class for other iterators and spliterators.
3281	>	*
3282	>	* Method advance visits once each still-valid node that was
3283	>	* reachable upon iterator construction. It might miss some that
3284	>	* were added to a bin after the bin was visited, which is OK wrt
3285	>	* consistency guarantees. Maintaining this property in the face
3286	>	* of possible ongoing resizes requires a fair amount of
3287	>	* bookkeeping state that is difficult to optimize away amidst
3288	>	* volatile accesses.  Even so, traversal maintains reasonable
3289	>	* throughput.
3290	>	*
3291	>	* Normally, iteration proceeds bin-by-bin traversing lists.
3292	>	* However, if the table has been resized, then all future steps
3293	>	* must traverse both the bin at the current index as well as at
3294	>	* (index + baseSize); and so on for further resizings. To
3295	>	* paranoically cope with potential sharing by users of iterators
3296	>	* across threads, iteration terminates if a bounds checks fails
3297	>	* for a table read.
3298		*/
3299	<	public boolean contains(Object value) {
3300	<	return containsValue(value);
3299	>	static class Traverser<K,V> {
3300	>	Node<K,V>[] tab;        // current table; updated if resized
3301	>	Node<K,V> next;         // the next entry to use
3302	>	TableStack<K,V> stack, spare; // to save/restore on ForwardingNodes
3303	>	int index;              // index of bin to use next
3304	>	int baseIndex;          // current index of initial table
3305	>	int baseLimit;          // index bound for initial table
3306	>	final int baseSize;     // initial table size
3307	>
3308	>	Traverser(Node<K,V>[] tab, int size, int index, int limit) {
3309	>	this.tab = tab;
3310	>	this.baseSize = size;
3311	>	this.baseIndex = this.index = index;
3312	>	this.baseLimit = limit;
3313	>	this.next = null;
3314	>	}
3315	>
3316	>	/**
3317	>	* Advances if possible, returning next valid node, or null if none.
3318	>	*/
3319	>	final Node<K,V> advance() {
3320	>	Node<K,V> e;
3321	>	if ((e = next) != null)
3322	>	e = e.next;
3323	>	for (;;) {
3324	>	Node<K,V>[] t; int i, n;  // must use locals in checks
3325	>	if (e != null)
3326	>	return next = e;
3327	>	if (baseIndex >= baseLimit || (t = tab) == null ||
3328	>	(n = t.length) <= (i = index) || i < 0)
3329	>	return next = null;
3330	>	if ((e = tabAt(t, i)) != null && e.hash < 0) {
3331	>	if (e instanceof ForwardingNode) {
3332	>	tab = ((ForwardingNode<K,V>)e).nextTable;
3333	>	e = null;
3334	>	pushState(t, i, n);
3335	>	continue;
3336	>	}
3337	>	else if (e instanceof TreeBin)
3338	>	e = ((TreeBin<K,V>)e).first;
3339	>	else
3340	>	e = null;
3341	>	}
3342	>	if (stack != null)
3343	>	recoverState(n);
3344	>	else if ((index = i + baseSize) >= n)
3345	>	index = ++baseIndex; // visit upper slots if present
3346	>	}
3347	>	}
3348	>
3349	>	/**
3350	>	* Saves traversal state upon encountering a forwarding node.
3351	>	*/
3352	>	private void pushState(Node<K,V>[] t, int i, int n) {
3353	>	TableStack<K,V> s = spare;  // reuse if possible
3354	>	if (s != null)
3355	>	spare = s.next;
3356	>	else
3357	>	s = new TableStack<K,V>();
3358	>	s.tab = t;
3359	>	s.length = n;
3360	>	s.index = i;
3361	>	s.next = stack;
3362	>	stack = s;
3363	>	}
3364	>
3365	>	/**
3366	>	* Possibly pops traversal state.
3367	>	*
3368	>	* @param n length of current table
3369	>	*/
3370	>	private void recoverState(int n) {
3371	>	TableStack<K,V> s; int len;
3372	>	while ((s = stack) != null && (index += (len = s.length)) >= n) {
3373	>	n = len;
3374	>	index = s.index;
3375	>	tab = s.tab;
3376	>	s.tab = null;
3377	>	TableStack<K,V> next = s.next;
3378	>	s.next = spare; // save for reuse
3379	>	stack = next;
3380	>	spare = s;
3381	>	}
3382	>	if (s == null && (index += baseSize) >= n)
3383	>	index = ++baseIndex;
3384	>	}
3385		}
3386
3387		/**
3388	<	* Maps the specified <tt>key</tt> to the specified
3389	<	* <tt>value</tt> in this table. Neither the key nor the
3390	<	* value can be <tt>null</tt>.
3388	>	* Base of key, value, and entry Iterators. Adds fields to
3389	>	* Traverser to support iterator.remove.
3390	>	*/
3391	>	static class BaseIterator<K,V> extends Traverser<K,V> {
3392	>	final ConcurrentHashMap<K,V> map;
3393	>	Node<K,V> lastReturned;
3394	>	BaseIterator(Node<K,V>[] tab, int size, int index, int limit,
3395	>	ConcurrentHashMap<K,V> map) {
3396	>	super(tab, size, index, limit);
3397	>	this.map = map;
3398	>	advance();
3399	>	}
3400	>
3401	>	public final boolean hasNext() { return next != null; }
3402	>	public final boolean hasMoreElements() { return next != null; }
3403	>
3404	>	public final void remove() {
3405	>	Node<K,V> p;
3406	>	if ((p = lastReturned) == null)
3407	>	throw new IllegalStateException();
3408	>	lastReturned = null;
3409	>	map.replaceNode(p.key, null, null);
3410	>	}
3411	>	}
3412	>
3413	>	static final class KeyIterator<K,V> extends BaseIterator<K,V>
3414	>	implements Iterator<K>, Enumeration<K> {
3415	>	KeyIterator(Node<K,V>[] tab, int size, int index, int limit,
3416	>	ConcurrentHashMap<K,V> map) {
3417	>	super(tab, size, index, limit, map);
3418	>	}
3419	>
3420	>	public final K next() {
3421	>	Node<K,V> p;
3422	>	if ((p = next) == null)
3423	>	throw new NoSuchElementException();
3424	>	K k = p.key;
3425	>	lastReturned = p;
3426	>	advance();
3427	>	return k;
3428	>	}
3429	>
3430	>	public final K nextElement() { return next(); }
3431	>	}
3432	>
3433	>	static final class ValueIterator<K,V> extends BaseIterator<K,V>
3434	>	implements Iterator<V>, Enumeration<V> {
3435	>	ValueIterator(Node<K,V>[] tab, int size, int index, int limit,
3436	>	ConcurrentHashMap<K,V> map) {
3437	>	super(tab, size, index, limit, map);
3438	>	}
3439	>
3440	>	public final V next() {
3441	>	Node<K,V> p;
3442	>	if ((p = next) == null)
3443	>	throw new NoSuchElementException();
3444	>	V v = p.val;
3445	>	lastReturned = p;
3446	>	advance();
3447	>	return v;
3448	>	}
3449	>
3450	>	public final V nextElement() { return next(); }
3451	>	}
3452	>
3453	>	static final class EntryIterator<K,V> extends BaseIterator<K,V>
3454	>	implements Iterator<Map.Entry<K,V>> {
3455	>	EntryIterator(Node<K,V>[] tab, int size, int index, int limit,
3456	>	ConcurrentHashMap<K,V> map) {
3457	>	super(tab, size, index, limit, map);
3458	>	}
3459	>
3460	>	public final Map.Entry<K,V> next() {
3461	>	Node<K,V> p;
3462	>	if ((p = next) == null)
3463	>	throw new NoSuchElementException();
3464	>	K k = p.key;
3465	>	V v = p.val;
3466	>	lastReturned = p;
3467	>	advance();
3468	>	return new MapEntry<K,V>(k, v, map);
3469	>	}
3470	>	}
3471	>
3472	>	/**
3473	>	* Exported Entry for EntryIterator.
3474	>	*/
3475	>	static final class MapEntry<K,V> implements Map.Entry<K,V> {
3476	>	final K key; // non-null
3477	>	V val;       // non-null
3478	>	final ConcurrentHashMap<K,V> map;
3479	>	MapEntry(K key, V val, ConcurrentHashMap<K,V> map) {
3480	>	this.key = key;
3481	>	this.val = val;
3482	>	this.map = map;
3483	>	}
3484	>	public K getKey()        { return key; }
3485	>	public V getValue()      { return val; }
3486	>	public int hashCode()    { return key.hashCode() ^ val.hashCode(); }
3487	>	public String toString() {
3488	>	return Helpers.mapEntryToString(key, val);
3489	>	}
3490	>
3491	>	public boolean equals(Object o) {
3492	>	Object k, v; Map.Entry<?,?> e;
3493	>	return ((o instanceof Map.Entry) &&
3494	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
3495	>	(v = e.getValue()) != null &&
3496	>	(k == key || k.equals(key)) &&
3497	>	(v == val || v.equals(val)));
3498	>	}
3499	>
3500	>	/**
3501	>	* Sets our entry's value and writes through to the map. The
3502	>	* value to return is somewhat arbitrary here. Since we do not
3503	>	* necessarily track asynchronous changes, the most recent
3504	>	* "previous" value could be different from what we return (or
3505	>	* could even have been removed, in which case the put will
3506	>	* re-establish). We do not and cannot guarantee more.
3507	>	*/
3508	>	public V setValue(V value) {
3509	>	if (value == null) throw new NullPointerException();
3510	>	V v = val;
3511	>	val = value;
3512	>	map.put(key, value);
3513	>	return v;
3514	>	}
3515	>	}
3516	>
3517	>	static final class KeySpliterator<K,V> extends Traverser<K,V>
3518	>	implements Spliterator<K> {
3519	>	long est;               // size estimate
3520	>	KeySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3521	>	long est) {
3522	>	super(tab, size, index, limit);
3523	>	this.est = est;
3524	>	}
3525	>
3526	>	public KeySpliterator<K,V> trySplit() {
3527	>	int i, f, h;
3528	>	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3529	>	new KeySpliterator<K,V>(tab, baseSize, baseLimit = h,
3530	>	f, est >>>= 1);
3531	>	}
3532	>
3533	>	public void forEachRemaining(Consumer<? super K> action) {
3534	>	if (action == null) throw new NullPointerException();
3535	>	for (Node<K,V> p; (p = advance()) != null;)
3536	>	action.accept(p.key);
3537	>	}
3538	>
3539	>	public boolean tryAdvance(Consumer<? super K> action) {
3540	>	if (action == null) throw new NullPointerException();
3541	>	Node<K,V> p;
3542	>	if ((p = advance()) == null)
3543	>	return false;
3544	>	action.accept(p.key);
3545	>	return true;
3546	>	}
3547	>
3548	>	public long estimateSize() { return est; }
3549	>
3550	>	public int characteristics() {
3551	>	return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3552	>	Spliterator.NONNULL;
3553	>	}
3554	>	}
3555	>
3556	>	static final class ValueSpliterator<K,V> extends Traverser<K,V>
3557	>	implements Spliterator<V> {
3558	>	long est;               // size estimate
3559	>	ValueSpliterator(Node<K,V>[] tab, int size, int index, int limit,
3560	>	long est) {
3561	>	super(tab, size, index, limit);
3562	>	this.est = est;
3563	>	}
3564	>
3565	>	public ValueSpliterator<K,V> trySplit() {
3566	>	int i, f, h;
3567	>	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3568	>	new ValueSpliterator<K,V>(tab, baseSize, baseLimit = h,
3569	>	f, est >>>= 1);
3570	>	}
3571	>
3572	>	public void forEachRemaining(Consumer<? super V> action) {
3573	>	if (action == null) throw new NullPointerException();
3574	>	for (Node<K,V> p; (p = advance()) != null;)
3575	>	action.accept(p.val);
3576	>	}
3577	>
3578	>	public boolean tryAdvance(Consumer<? super V> action) {
3579	>	if (action == null) throw new NullPointerException();
3580	>	Node<K,V> p;
3581	>	if ((p = advance()) == null)
3582	>	return false;
3583	>	action.accept(p.val);
3584	>	return true;
3585	>	}
3586	>
3587	>	public long estimateSize() { return est; }
3588	>
3589	>	public int characteristics() {
3590	>	return Spliterator.CONCURRENT | Spliterator.NONNULL;
3591	>	}
3592	>	}
3593	>
3594	>	static final class EntrySpliterator<K,V> extends Traverser<K,V>
3595	>	implements Spliterator<Map.Entry<K,V>> {
3596	>	final ConcurrentHashMap<K,V> map; // To export MapEntry
3597	>	long est;               // size estimate
3598	>	EntrySpliterator(Node<K,V>[] tab, int size, int index, int limit,
3599	>	long est, ConcurrentHashMap<K,V> map) {
3600	>	super(tab, size, index, limit);
3601	>	this.map = map;
3602	>	this.est = est;
3603	>	}
3604	>
3605	>	public EntrySpliterator<K,V> trySplit() {
3606	>	int i, f, h;
3607	>	return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null :
3608	>	new EntrySpliterator<K,V>(tab, baseSize, baseLimit = h,
3609	>	f, est >>>= 1, map);
3610	>	}
3611	>
3612	>	public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
3613	>	if (action == null) throw new NullPointerException();
3614	>	for (Node<K,V> p; (p = advance()) != null; )
3615	>	action.accept(new MapEntry<K,V>(p.key, p.val, map));
3616	>	}
3617	>
3618	>	public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
3619	>	if (action == null) throw new NullPointerException();
3620	>	Node<K,V> p;
3621	>	if ((p = advance()) == null)
3622	>	return false;
3623	>	action.accept(new MapEntry<K,V>(p.key, p.val, map));
3624	>	return true;
3625	>	}
3626	>
3627	>	public long estimateSize() { return est; }
3628	>
3629	>	public int characteristics() {
3630	>	return Spliterator.DISTINCT | Spliterator.CONCURRENT |
3631	>	Spliterator.NONNULL;
3632	>	}
3633	>	}
3634	>
3635	>	// Parallel bulk operations
3636	>
3637	>	/**
3638	>	* Computes initial batch value for bulk tasks. The returned value
3639	>	* is approximately exp2 of the number of times (minus one) to
3640	>	* split task by two before executing leaf action. This value is
3641	>	* faster to compute and more convenient to use as a guide to
3642	>	* splitting than is the depth, since it is used while dividing by
3643	>	* two anyway.
3644	>	*/
3645	>	final int batchFor(long b) {
3646	>	long n;
3647	>	if (b == Long.MAX_VALUE || (n = sumCount()) <= 1L || n < b)
3648	>	return 0;
3649	>	int sp = ForkJoinPool.getCommonPoolParallelism() << 2; // slack of 4
3650	>	return (b <= 0L || (n /= b) >= sp) ? sp : (int)n;
3651	>	}
3652	>
3653	>	/**
3654	>	* Performs the given action for each (key, value).
3655		*
3656	<	* <p> The value can be retrieved by calling the <tt>get</tt> method
3657	<	* with a key that is equal to the original key.
3656	>	* @param parallelismThreshold the (estimated) number of elements
3657	>	* needed for this operation to be executed in parallel
3658	>	* @param action the action
3659	>	* @since 1.8
3660	>	*/
3661	>	public void forEach(long parallelismThreshold,
3662	>	BiConsumer<? super K,? super V> action) {
3663	>	if (action == null) throw new NullPointerException();
3664	>	new ForEachMappingTask<K,V>
3665	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3666	>	action).invoke();
3667	>	}
3668	>
3669	>	/**
3670	>	* Performs the given action for each non-null transformation
3671	>	* of each (key, value).
3672		*
3673	<	* @param      key     the table key.
3674	<	* @param      value   the value.
3675	<	* @return     the previous value of the specified key in this table,
3676	<	*             or <tt>null</tt> if it did not have one.
3677	<	* @throws  NullPointerException  if the key or value is
3678	<	*               <tt>null</tt>.
3673	>	* @param parallelismThreshold the (estimated) number of elements
3674	>	* needed for this operation to be executed in parallel
3675	>	* @param transformer a function returning the transformation
3676	>	* for an element, or null if there is no transformation (in
3677	>	* which case the action is not applied)
3678	>	* @param action the action
3679	>	* @param <U> the return type of the transformer
3680	>	* @since 1.8
3681		*/
3682	<	public V put(K key, V value) {
3683	<	if (value == null)
3682	>	public <U> void forEach(long parallelismThreshold,
3683	>	BiFunction<? super K, ? super V, ? extends U> transformer,
3684	>	Consumer<? super U> action) {
3685	>	if (transformer == null || action == null)
3686		throw new NullPointerException();
3687	<	int hash = hash(key);
3688	<	return segmentFor(hash).put(key, hash, value, false);
3687	>	new ForEachTransformedMappingTask<K,V,U>
3688	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3689	>	transformer, action).invoke();
3690		}
3691
3692		/**
3693	<	* If the specified key is not already associated
3694	<	* with a value, associate it with the given value.
3695	<	* This is equivalent to
3696	<	* <pre>
3697	<	*   if (!map.containsKey(key))
3698	<	*      return map.put(key, value);
3699	<	*   else
3700	<	*      return map.get(key);
3701	<	* </pre>
3702	<	* Except that the action is performed atomically.
3703	<	* @param key key with which the specified value is to be associated.
3704	<	* @param value value to be associated with the specified key.
3705	<	* @return previous value associated with specified key, or <tt>null</tt>
3706	<	*         if there was no mapping for key.
867	<	* @throws NullPointerException if the specified key or value is
868	<	*            <tt>null</tt>.
3693	>	* Returns a non-null result from applying the given search
3694	>	* function on each (key, value), or null if none.  Upon
3695	>	* success, further element processing is suppressed and the
3696	>	* results of any other parallel invocations of the search
3697	>	* function are ignored.
3698	>	*
3699	>	* @param parallelismThreshold the (estimated) number of elements
3700	>	* needed for this operation to be executed in parallel
3701	>	* @param searchFunction a function returning a non-null
3702	>	* result on success, else null
3703	>	* @param <U> the return type of the search function
3704	>	* @return a non-null result from applying the given search
3705	>	* function on each (key, value), or null if none
3706	>	* @since 1.8
3707		*/
3708	<	public V putIfAbsent(K key, V value) {
3709	<	if (value == null)
3708	>	public <U> U search(long parallelismThreshold,
3709	>	BiFunction<? super K, ? super V, ? extends U> searchFunction) {
3710	>	if (searchFunction == null) throw new NullPointerException();
3711	>	return new SearchMappingsTask<K,V,U>
3712	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3713	>	searchFunction, new AtomicReference<U>()).invoke();
3714	>	}
3715	>
3716	>	/**
3717	>	* Returns the result of accumulating the given transformation
3718	>	* of all (key, value) pairs using the given reducer to
3719	>	* combine values, or null if none.
3720	>	*
3721	>	* @param parallelismThreshold the (estimated) number of elements
3722	>	* needed for this operation to be executed in parallel
3723	>	* @param transformer a function returning the transformation
3724	>	* for an element, or null if there is no transformation (in
3725	>	* which case it is not combined)
3726	>	* @param reducer a commutative associative combining function
3727	>	* @param <U> the return type of the transformer
3728	>	* @return the result of accumulating the given transformation
3729	>	* of all (key, value) pairs
3730	>	* @since 1.8
3731	>	*/
3732	>	public <U> U reduce(long parallelismThreshold,
3733	>	BiFunction<? super K, ? super V, ? extends U> transformer,
3734	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3735	>	if (transformer == null || reducer == null)
3736		throw new NullPointerException();
3737	<	int hash = hash(key);
3738	<	return segmentFor(hash).put(key, hash, value, true);
3737	>	return new MapReduceMappingsTask<K,V,U>
3738	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3739	>	null, transformer, reducer).invoke();
3740		}
3741
3742	+	/**
3743	+	* Returns the result of accumulating the given transformation
3744	+	* of all (key, value) pairs using the given reducer to
3745	+	* combine values, and the given basis as an identity value.
3746	+	*
3747	+	* @param parallelismThreshold the (estimated) number of elements
3748	+	* needed for this operation to be executed in parallel
3749	+	* @param transformer a function returning the transformation
3750	+	* for an element
3751	+	* @param basis the identity (initial default value) for the reduction
3752	+	* @param reducer a commutative associative combining function
3753	+	* @return the result of accumulating the given transformation
3754	+	* of all (key, value) pairs
3755	+	* @since 1.8
3756	+	*/
3757	+	public double reduceToDouble(long parallelismThreshold,
3758	+	ToDoubleBiFunction<? super K, ? super V> transformer,
3759	+	double basis,
3760	+	DoubleBinaryOperator reducer) {
3761	+	if (transformer == null || reducer == null)
3762	+	throw new NullPointerException();
3763	+	return new MapReduceMappingsToDoubleTask<K,V>
3764	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3765	+	null, transformer, basis, reducer).invoke();
3766	+	}
3767
3768		/**
3769	<	* Copies all of the mappings from the specified map to this one.
3769	>	* Returns the result of accumulating the given transformation
3770	>	* of all (key, value) pairs using the given reducer to
3771	>	* combine values, and the given basis as an identity value.
3772		*
3773	<	* These mappings replace any mappings that this map had for any of the
3774	<	* keys currently in the specified Map.
3773	>	* @param parallelismThreshold the (estimated) number of elements
3774	>	* needed for this operation to be executed in parallel
3775	>	* @param transformer a function returning the transformation
3776	>	* for an element
3777	>	* @param basis the identity (initial default value) for the reduction
3778	>	* @param reducer a commutative associative combining function
3779	>	* @return the result of accumulating the given transformation
3780	>	* of all (key, value) pairs
3781	>	* @since 1.8
3782	>	*/
3783	>	public long reduceToLong(long parallelismThreshold,
3784	>	ToLongBiFunction<? super K, ? super V> transformer,
3785	>	long basis,
3786	>	LongBinaryOperator reducer) {
3787	>	if (transformer == null || reducer == null)
3788	>	throw new NullPointerException();
3789	>	return new MapReduceMappingsToLongTask<K,V>
3790	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3791	>	null, transformer, basis, reducer).invoke();
3792	>	}
3793	>
3794	>	/**
3795	>	* Returns the result of accumulating the given transformation
3796	>	* of all (key, value) pairs using the given reducer to
3797	>	* combine values, and the given basis as an identity value.
3798		*
3799	<	* @param t Mappings to be stored in this map.
3799	>	* @param parallelismThreshold the (estimated) number of elements
3800	>	* needed for this operation to be executed in parallel
3801	>	* @param transformer a function returning the transformation
3802	>	* for an element
3803	>	* @param basis the identity (initial default value) for the reduction
3804	>	* @param reducer a commutative associative combining function
3805	>	* @return the result of accumulating the given transformation
3806	>	* of all (key, value) pairs
3807	>	* @since 1.8
3808		*/
3809	<	public void putAll(Map<? extends K, ? extends V> t) {
3810	<	for (Iterator<? extends Map.Entry<? extends K, ? extends V>> it = (Iterator<? extends Map.Entry<? extends K, ? extends V>>) t.entrySet().iterator(); it.hasNext(); ) {
3811	<	Entry<? extends K, ? extends V> e = it.next();
3812	<	put(e.getKey(), e.getValue());
3813	<	}
3809	>	public int reduceToInt(long parallelismThreshold,
3810	>	ToIntBiFunction<? super K, ? super V> transformer,
3811	>	int basis,
3812	>	IntBinaryOperator reducer) {
3813	>	if (transformer == null || reducer == null)
3814	>	throw new NullPointerException();
3815	>	return new MapReduceMappingsToIntTask<K,V>
3816	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3817	>	null, transformer, basis, reducer).invoke();
3818		}
3819
3820		/**
3821	<	* Removes the key (and its corresponding value) from this
895	<	* table. This method does nothing if the key is not in the table.
3821	>	* Performs the given action for each key.
3822		*
3823	<	* @param   key   the key that needs to be removed.
3824	<	* @return  the value to which the key had been mapped in this table,
3825	<	*          or <tt>null</tt> if the key did not have a mapping.
3826	<	* @throws  NullPointerException  if the key is
901	<	*               <tt>null</tt>.
3823	>	* @param parallelismThreshold the (estimated) number of elements
3824	>	* needed for this operation to be executed in parallel
3825	>	* @param action the action
3826	>	* @since 1.8
3827		*/
3828	<	public V remove(Object key) {
3829	<	int hash = hash(key);
3830	<	return segmentFor(hash).remove(key, hash, null);
3828	>	public void forEachKey(long parallelismThreshold,
3829	>	Consumer<? super K> action) {
3830	>	if (action == null) throw new NullPointerException();
3831	>	new ForEachKeyTask<K,V>
3832	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3833	>	action).invoke();
3834		}
3835
3836		/**
3837	<	* Remove entry for key only if currently mapped to given value.
3838	<	* Acts as
3839	<	* <pre>
3840	<	*  if (map.get(key).equals(value)) {
3841	<	*     map.remove(key);
3842	<	*     return true;
3843	<	* } else return false;
3844	<	* </pre>
3845	<	* except that the action is performed atomically.
3846	<	* @param key key with which the specified value is associated.
3847	<	* @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>.
3837	>	* Performs the given action for each non-null transformation
3838	>	* of each key.
3839	>	*
3840	>	* @param parallelismThreshold the (estimated) number of elements
3841	>	* needed for this operation to be executed in parallel
3842	>	* @param transformer a function returning the transformation
3843	>	* for an element, or null if there is no transformation (in
3844	>	* which case the action is not applied)
3845	>	* @param action the action
3846	>	* @param <U> the return type of the transformer
3847	>	* @since 1.8
3848		*/
3849	<	public boolean remove(Object key, Object value) {
3850	<	int hash = hash(key);
3851	<	return segmentFor(hash).remove(key, hash, value) != null;
3849	>	public <U> void forEachKey(long parallelismThreshold,
3850	>	Function<? super K, ? extends U> transformer,
3851	>	Consumer<? super U> action) {
3852	>	if (transformer == null || action == null)
3853	>	throw new NullPointerException();
3854	>	new ForEachTransformedKeyTask<K,V,U>
3855	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3856	>	transformer, action).invoke();
3857		}
3858
3859	+	/**
3860	+	* Returns a non-null result from applying the given search
3861	+	* function on each key, or null if none. Upon success,
3862	+	* further element processing is suppressed and the results of
3863	+	* any other parallel invocations of the search function are
3864	+	* ignored.
3865	+	*
3866	+	* @param parallelismThreshold the (estimated) number of elements
3867	+	* needed for this operation to be executed in parallel
3868	+	* @param searchFunction a function returning a non-null
3869	+	* result on success, else null
3870	+	* @param <U> the return type of the search function
3871	+	* @return a non-null result from applying the given search
3872	+	* function on each key, or null if none
3873	+	* @since 1.8
3874	+	*/
3875	+	public <U> U searchKeys(long parallelismThreshold,
3876	+	Function<? super K, ? extends U> searchFunction) {
3877	+	if (searchFunction == null) throw new NullPointerException();
3878	+	return new SearchKeysTask<K,V,U>
3879	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3880	+	searchFunction, new AtomicReference<U>()).invoke();
3881	+	}
3882
3883		/**
3884	<	* Replace entry for key only if currently mapped to given value.
3885	<	* Acts as
3886	<	* <pre>
3887	<	*  if (map.get(key).equals(oldValue)) {
3888	<	*     map.put(key, newValue);
3889	<	*     return true;
3890	<	* } else return false;
3891	<	* </pre>
3892	<	* 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>.
3884	>	* Returns the result of accumulating all keys using the given
3885	>	* reducer to combine values, or null if none.
3886	>	*
3887	>	* @param parallelismThreshold the (estimated) number of elements
3888	>	* needed for this operation to be executed in parallel
3889	>	* @param reducer a commutative associative combining function
3890	>	* @return the result of accumulating all keys using the given
3891	>	* reducer to combine values, or null if none
3892	>	* @since 1.8
3893		*/
3894	<	public boolean replace(K key, V oldValue, V newValue) {
3895	<	if (oldValue == null || newValue == null)
3894	>	public K reduceKeys(long parallelismThreshold,
3895	>	BiFunction<? super K, ? super K, ? extends K> reducer) {
3896	>	if (reducer == null) throw new NullPointerException();
3897	>	return new ReduceKeysTask<K,V>
3898	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3899	>	null, reducer).invoke();
3900	>	}
3901	>
3902	>	/**
3903	>	* Returns the result of accumulating the given transformation
3904	>	* of all keys using the given reducer to combine values, or
3905	>	* null if none.
3906	>	*
3907	>	* @param parallelismThreshold the (estimated) number of elements
3908	>	* needed for this operation to be executed in parallel
3909	>	* @param transformer a function returning the transformation
3910	>	* for an element, or null if there is no transformation (in
3911	>	* which case it is not combined)
3912	>	* @param reducer a commutative associative combining function
3913	>	* @param <U> the return type of the transformer
3914	>	* @return the result of accumulating the given transformation
3915	>	* of all keys
3916	>	* @since 1.8
3917	>	*/
3918	>	public <U> U reduceKeys(long parallelismThreshold,
3919	>	Function<? super K, ? extends U> transformer,
3920	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
3921	>	if (transformer == null || reducer == null)
3922		throw new NullPointerException();
3923	<	int hash = hash(key);
3924	<	return segmentFor(hash).replace(key, hash, oldValue, newValue);
3923	>	return new MapReduceKeysTask<K,V,U>
3924	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3925	>	null, transformer, reducer).invoke();
3926		}
3927
3928		/**
3929	<	* Replace entry for key only if currently mapped to some value.
3930	<	* Acts as
3931	<	* <pre>
3932	<	*  if ((map.containsKey(key)) {
3933	<	*     return map.put(key, value);
3934	<	* } else return null;
3935	<	* </pre>
3936	<	* except that the action is performed atomically.
3937	<	* @param key key with which the specified value is associated.
3938	<	* @param value value to be associated with the specified key.
3939	<	* @return previous value associated with specified key, or <tt>null</tt>
3940	<	*         if there was no mapping for key.
3941	<	* @throws NullPointerException if the specified key or value is
968	<	*            <tt>null</tt>.
3929	>	* Returns the result of accumulating the given transformation
3930	>	* of all keys using the given reducer to combine values, and
3931	>	* the given basis as an identity value.
3932	>	*
3933	>	* @param parallelismThreshold the (estimated) number of elements
3934	>	* needed for this operation to be executed in parallel
3935	>	* @param transformer a function returning the transformation
3936	>	* for an element
3937	>	* @param basis the identity (initial default value) for the reduction
3938	>	* @param reducer a commutative associative combining function
3939	>	* @return the result of accumulating the given transformation
3940	>	* of all keys
3941	>	* @since 1.8
3942		*/
3943	<	public V replace(K key, V value) {
3944	<	if (value == null)
3943	>	public double reduceKeysToDouble(long parallelismThreshold,
3944	>	ToDoubleFunction<? super K> transformer,
3945	>	double basis,
3946	>	DoubleBinaryOperator reducer) {
3947	>	if (transformer == null || reducer == null)
3948		throw new NullPointerException();
3949	<	int hash = hash(key);
3950	<	return segmentFor(hash).replace(key, hash, value);
3949	>	return new MapReduceKeysToDoubleTask<K,V>
3950	>	(null, batchFor(parallelismThreshold), 0, 0, table,
3951	>	null, transformer, basis, reducer).invoke();
3952		}
3953
3954	+	/**
3955	+	* Returns the result of accumulating the given transformation
3956	+	* of all keys using the given reducer to combine values, and
3957	+	* the given basis as an identity value.
3958	+	*
3959	+	* @param parallelismThreshold the (estimated) number of elements
3960	+	* needed for this operation to be executed in parallel
3961	+	* @param transformer a function returning the transformation
3962	+	* for an element
3963	+	* @param basis the identity (initial default value) for the reduction
3964	+	* @param reducer a commutative associative combining function
3965	+	* @return the result of accumulating the given transformation
3966	+	* of all keys
3967	+	* @since 1.8
3968	+	*/
3969	+	public long reduceKeysToLong(long parallelismThreshold,
3970	+	ToLongFunction<? super K> transformer,
3971	+	long basis,
3972	+	LongBinaryOperator reducer) {
3973	+	if (transformer == null || reducer == null)
3974	+	throw new NullPointerException();
3975	+	return new MapReduceKeysToLongTask<K,V>
3976	+	(null, batchFor(parallelismThreshold), 0, 0, table,
3977	+	null, transformer, basis, reducer).invoke();
3978	+	}
3979
3980		/**
3981	<	* Removes all mappings from this map.
3981	>	* Returns the result of accumulating the given transformation
3982	>	* of all keys using the given reducer to combine values, and
3983	>	* the given basis as an identity value.
3984	>	*
3985	>	* @param parallelismThreshold the (estimated) number of elements
3986	>	* needed for this operation to be executed in parallel
3987	>	* @param transformer a function returning the transformation
3988	>	* for an element
3989	>	* @param basis the identity (initial default value) for the reduction
3990	>	* @param reducer a commutative associative combining function
3991	>	* @return the result of accumulating the given transformation
3992	>	* of all keys
3993	>	* @since 1.8
3994		*/
3995	<	public void clear() {
3996	<	for (int i = 0; i < segments.length; ++i)
3997	<	segments[i].clear();
3995	>	public int reduceKeysToInt(long parallelismThreshold,
3996	>	ToIntFunction<? super K> transformer,
3997	>	int basis,
3998	>	IntBinaryOperator reducer) {
3999	>	if (transformer == null || reducer == null)
4000	>	throw new NullPointerException();
4001	>	return new MapReduceKeysToIntTask<K,V>
4002	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4003	>	null, transformer, basis, reducer).invoke();
4004		}
4005
4006		/**
4007	<	* Returns a set view of the keys contained in this map.  The set is
4008	<	* backed by the map, so changes to the map are reflected in the set, and
4009	<	* vice-versa.  The set supports element removal, which removes the
4010	<	* corresponding mapping from this map, via the <tt>Iterator.remove</tt>,
4011	<	* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and
4012	<	* <tt>clear</tt> operations.  It does not support the <tt>add</tt> or
4013	<	* <tt>addAll</tt> operations.
4014	<	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
4015	<	* will never throw {@link java.util.ConcurrentModificationException},
4016	<	* and guarantees to traverse elements as they existed upon
4017	<	* construction of the iterator, and may (but is not guaranteed to)
4018	<	* reflect any modifications subsequent to construction.
4019	<	*
4020	<	* @return a set view of the keys contained in this map.
1001	<	*/
1002	<	public Set<K> keySet() {
1003	<	Set<K> ks = keySet;
1004	<	return (ks != null) ? ks : (keySet = new KeySet());
4007	>	* Performs the given action for each value.
4008	>	*
4009	>	* @param parallelismThreshold the (estimated) number of elements
4010	>	* needed for this operation to be executed in parallel
4011	>	* @param action the action
4012	>	* @since 1.8
4013	>	*/
4014	>	public void forEachValue(long parallelismThreshold,
4015	>	Consumer<? super V> action) {
4016	>	if (action == null)
4017	>	throw new NullPointerException();
4018	>	new ForEachValueTask<K,V>
4019	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4020	>	action).invoke();
4021		}
4022
4023	+	/**
4024	+	* Performs the given action for each non-null transformation
4025	+	* of each value.
4026	+	*
4027	+	* @param parallelismThreshold the (estimated) number of elements
4028	+	* needed for this operation to be executed in parallel
4029	+	* @param transformer a function returning the transformation
4030	+	* for an element, or null if there is no transformation (in
4031	+	* which case the action is not applied)
4032	+	* @param action the action
4033	+	* @param <U> the return type of the transformer
4034	+	* @since 1.8
4035	+	*/
4036	+	public <U> void forEachValue(long parallelismThreshold,
4037	+	Function<? super V, ? extends U> transformer,
4038	+	Consumer<? super U> action) {
4039	+	if (transformer == null || action == null)
4040	+	throw new NullPointerException();
4041	+	new ForEachTransformedValueTask<K,V,U>
4042	+	(null, batchFor(parallelismThreshold), 0, 0, table,
4043	+	transformer, action).invoke();
4044	+	}
4045
4046		/**
4047	<	* Returns a collection view of the values contained in this map.  The
4048	<	* collection is backed by the map, so changes to the map are reflected in
4049	<	* the collection, and vice-versa.  The collection supports element
4050	<	* removal, which removes the corresponding mapping from this map, via the
4051	<	* <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.
4047	>	* Returns a non-null result from applying the given search
4048	>	* function on each value, or null if none.  Upon success,
4049	>	* further element processing is suppressed and the results of
4050	>	* any other parallel invocations of the search function are
4051	>	* ignored.
4052		*
4053	<	* @return a collection view of the values contained in this map.
4053	>	* @param parallelismThreshold the (estimated) number of elements
4054	>	* needed for this operation to be executed in parallel
4055	>	* @param searchFunction a function returning a non-null
4056	>	* result on success, else null
4057	>	* @param <U> the return type of the search function
4058	>	* @return a non-null result from applying the given search
4059	>	* function on each value, or null if none
4060	>	* @since 1.8
4061		*/
4062	<	public Collection<V> values() {
4063	<	Collection<V> vs = values;
4064	<	return (vs != null) ? vs : (values = new Values());
4062	>	public <U> U searchValues(long parallelismThreshold,
4063	>	Function<? super V, ? extends U> searchFunction) {
4064	>	if (searchFunction == null) throw new NullPointerException();
4065	>	return new SearchValuesTask<K,V,U>
4066	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4067	>	searchFunction, new AtomicReference<U>()).invoke();
4068		}
4069
4070	+	/**
4071	+	* Returns the result of accumulating all values using the
4072	+	* given reducer to combine values, or null if none.
4073	+	*
4074	+	* @param parallelismThreshold the (estimated) number of elements
4075	+	* needed for this operation to be executed in parallel
4076	+	* @param reducer a commutative associative combining function
4077	+	* @return the result of accumulating all values
4078	+	* @since 1.8
4079	+	*/
4080	+	public V reduceValues(long parallelismThreshold,
4081	+	BiFunction<? super V, ? super V, ? extends V> reducer) {
4082	+	if (reducer == null) throw new NullPointerException();
4083	+	return new ReduceValuesTask<K,V>
4084	+	(null, batchFor(parallelismThreshold), 0, 0, table,
4085	+	null, reducer).invoke();
4086	+	}
4087
4088		/**
4089	<	* Returns a collection view of the mappings contained in this map.  Each
4090	<	* element in the returned collection is a <tt>Map.Entry</tt>.  The
4091	<	* 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.
4089	>	* Returns the result of accumulating the given transformation
4090	>	* of all values using the given reducer to combine values, or
4091	>	* null if none.
4092		*
4093	<	* @return a collection view of the mappings contained in this map.
4093	>	* @param parallelismThreshold the (estimated) number of elements
4094	>	* needed for this operation to be executed in parallel
4095	>	* @param transformer a function returning the transformation
4096	>	* for an element, or null if there is no transformation (in
4097	>	* which case it is not combined)
4098	>	* @param reducer a commutative associative combining function
4099	>	* @param <U> the return type of the transformer
4100	>	* @return the result of accumulating the given transformation
4101	>	* of all values
4102	>	* @since 1.8
4103		*/
4104	<	public Set<Map.Entry<K,V>> entrySet() {
4105	<	Set<Map.Entry<K,V>> es = entrySet;
4106	<	return (es != null) ? es : (entrySet = (Set<Map.Entry<K,V>>) (Set) new EntrySet());
4104	>	public <U> U reduceValues(long parallelismThreshold,
4105	>	Function<? super V, ? extends U> transformer,
4106	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
4107	>	if (transformer == null || reducer == null)
4108	>	throw new NullPointerException();
4109	>	return new MapReduceValuesTask<K,V,U>
4110	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4111	>	null, transformer, reducer).invoke();
4112		}
4113
4114	+	/**
4115	+	* Returns the result of accumulating the given transformation
4116	+	* of all values using the given reducer to combine values,
4117	+	* and the given basis as an identity value.
4118	+	*
4119	+	* @param parallelismThreshold the (estimated) number of elements
4120	+	* needed for this operation to be executed in parallel
4121	+	* @param transformer a function returning the transformation
4122	+	* for an element
4123	+	* @param basis the identity (initial default value) for the reduction
4124	+	* @param reducer a commutative associative combining function
4125	+	* @return the result of accumulating the given transformation
4126	+	* of all values
4127	+	* @since 1.8
4128	+	*/
4129	+	public double reduceValuesToDouble(long parallelismThreshold,
4130	+	ToDoubleFunction<? super V> transformer,
4131	+	double basis,
4132	+	DoubleBinaryOperator reducer) {
4133	+	if (transformer == null || reducer == null)
4134	+	throw new NullPointerException();
4135	+	return new MapReduceValuesToDoubleTask<K,V>
4136	+	(null, batchFor(parallelismThreshold), 0, 0, table,
4137	+	null, transformer, basis, reducer).invoke();
4138	+	}
4139
4140		/**
4141	<	* Returns an enumeration of the keys in this table.
4141	>	* Returns the result of accumulating the given transformation
4142	>	* of all values using the given reducer to combine values,
4143	>	* and the given basis as an identity value.
4144		*
4145	<	* @return  an enumeration of the keys in this table.
4146	<	* @see     #keySet
4145	>	* @param parallelismThreshold the (estimated) number of elements
4146	>	* needed for this operation to be executed in parallel
4147	>	* @param transformer a function returning the transformation
4148	>	* for an element
4149	>	* @param basis the identity (initial default value) for the reduction
4150	>	* @param reducer a commutative associative combining function
4151	>	* @return the result of accumulating the given transformation
4152	>	* of all values
4153	>	* @since 1.8
4154		*/
4155	<	public Enumeration<K> keys() {
4156	<	return new KeyIterator();
4155	>	public long reduceValuesToLong(long parallelismThreshold,
4156	>	ToLongFunction<? super V> transformer,
4157	>	long basis,
4158	>	LongBinaryOperator reducer) {
4159	>	if (transformer == null || reducer == null)
4160	>	throw new NullPointerException();
4161	>	return new MapReduceValuesToLongTask<K,V>
4162	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4163	>	null, transformer, basis, reducer).invoke();
4164		}
4165
4166		/**
4167	<	* Returns an enumeration of the values in this table.
4167	>	* Returns the result of accumulating the given transformation
4168	>	* of all values using the given reducer to combine values,
4169	>	* and the given basis as an identity value.
4170		*
4171	<	* @return  an enumeration of the values in this table.
4172	<	* @see     #values
4171	>	* @param parallelismThreshold the (estimated) number of elements
4172	>	* needed for this operation to be executed in parallel
4173	>	* @param transformer a function returning the transformation
4174	>	* for an element
4175	>	* @param basis the identity (initial default value) for the reduction
4176	>	* @param reducer a commutative associative combining function
4177	>	* @return the result of accumulating the given transformation
4178	>	* of all values
4179	>	* @since 1.8
4180		*/
4181	<	public Enumeration<V> elements() {
4182	<	return new ValueIterator();
4181	>	public int reduceValuesToInt(long parallelismThreshold,
4182	>	ToIntFunction<? super V> transformer,
4183	>	int basis,
4184	>	IntBinaryOperator reducer) {
4185	>	if (transformer == null || reducer == null)
4186	>	throw new NullPointerException();
4187	>	return new MapReduceValuesToIntTask<K,V>
4188	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4189	>	null, transformer, basis, reducer).invoke();
4190		}
4191
4192	<	/* ---------------- Iterator Support -------------- */
4192	>	/**
4193	>	* Performs the given action for each entry.
4194	>	*
4195	>	* @param parallelismThreshold the (estimated) number of elements
4196	>	* needed for this operation to be executed in parallel
4197	>	* @param action the action
4198	>	* @since 1.8
4199	>	*/
4200	>	public void forEachEntry(long parallelismThreshold,
4201	>	Consumer<? super Map.Entry<K,V>> action) {
4202	>	if (action == null) throw new NullPointerException();
4203	>	new ForEachEntryTask<K,V>(null, batchFor(parallelismThreshold), 0, 0, table,
4204	>	action).invoke();
4205	>	}
4206
4207	<	abstract class HashIterator {
4208	<	int nextSegmentIndex;
4209	<	int nextTableIndex;
4210	<	HashEntry[] currentTable;
4211	<	HashEntry<K, V> nextEntry;
4212	<	HashEntry<K, V> lastReturned;
4207	>	/**
4208	>	* Performs the given action for each non-null transformation
4209	>	* of each entry.
4210	>	*
4211	>	* @param parallelismThreshold the (estimated) number of elements
4212	>	* needed for this operation to be executed in parallel
4213	>	* @param transformer a function returning the transformation
4214	>	* for an element, or null if there is no transformation (in
4215	>	* which case the action is not applied)
4216	>	* @param action the action
4217	>	* @param <U> the return type of the transformer
4218	>	* @since 1.8
4219	>	*/
4220	>	public <U> void forEachEntry(long parallelismThreshold,
4221	>	Function<Map.Entry<K,V>, ? extends U> transformer,
4222	>	Consumer<? super U> action) {
4223	>	if (transformer == null || action == null)
4224	>	throw new NullPointerException();
4225	>	new ForEachTransformedEntryTask<K,V,U>
4226	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4227	>	transformer, action).invoke();
4228	>	}
4229
4230	<	HashIterator() {
4231	<	nextSegmentIndex = segments.length - 1;
4232	<	nextTableIndex = -1;
4233	<	advance();
4234	<	}
4230	>	/**
4231	>	* Returns a non-null result from applying the given search
4232	>	* function on each entry, or null if none.  Upon success,
4233	>	* further element processing is suppressed and the results of
4234	>	* any other parallel invocations of the search function are
4235	>	* ignored.
4236	>	*
4237	>	* @param parallelismThreshold the (estimated) number of elements
4238	>	* needed for this operation to be executed in parallel
4239	>	* @param searchFunction a function returning a non-null
4240	>	* result on success, else null
4241	>	* @param <U> the return type of the search function
4242	>	* @return a non-null result from applying the given search
4243	>	* function on each entry, or null if none
4244	>	* @since 1.8
4245	>	*/
4246	>	public <U> U searchEntries(long parallelismThreshold,
4247	>	Function<Map.Entry<K,V>, ? extends U> searchFunction) {
4248	>	if (searchFunction == null) throw new NullPointerException();
4249	>	return new SearchEntriesTask<K,V,U>
4250	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4251	>	searchFunction, new AtomicReference<U>()).invoke();
4252	>	}
4253
4254	<	public boolean hasMoreElements() { return hasNext(); }
4254	>	/**
4255	>	* Returns the result of accumulating all entries using the
4256	>	* given reducer to combine values, or null if none.
4257	>	*
4258	>	* @param parallelismThreshold the (estimated) number of elements
4259	>	* needed for this operation to be executed in parallel
4260	>	* @param reducer a commutative associative combining function
4261	>	* @return the result of accumulating all entries
4262	>	* @since 1.8
4263	>	*/
4264	>	public Map.Entry<K,V> reduceEntries(long parallelismThreshold,
4265	>	BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
4266	>	if (reducer == null) throw new NullPointerException();
4267	>	return new ReduceEntriesTask<K,V>
4268	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4269	>	null, reducer).invoke();
4270	>	}
4271
4272	<	final void advance() {
4273	<	if (nextEntry != null && (nextEntry = nextEntry.next) != null)
4274	<	return;
4272	>	/**
4273	>	* Returns the result of accumulating the given transformation
4274	>	* of all entries using the given reducer to combine values,
4275	>	* or null if none.
4276	>	*
4277	>	* @param parallelismThreshold the (estimated) number of elements
4278	>	* needed for this operation to be executed in parallel
4279	>	* @param transformer a function returning the transformation
4280	>	* for an element, or null if there is no transformation (in
4281	>	* which case it is not combined)
4282	>	* @param reducer a commutative associative combining function
4283	>	* @param <U> the return type of the transformer
4284	>	* @return the result of accumulating the given transformation
4285	>	* of all entries
4286	>	* @since 1.8
4287	>	*/
4288	>	public <U> U reduceEntries(long parallelismThreshold,
4289	>	Function<Map.Entry<K,V>, ? extends U> transformer,
4290	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
4291	>	if (transformer == null || reducer == null)
4292	>	throw new NullPointerException();
4293	>	return new MapReduceEntriesTask<K,V,U>
4294	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4295	>	null, transformer, reducer).invoke();
4296	>	}
4297
4298	<	while (nextTableIndex >= 0) {
4299	<	if ( (nextEntry = (HashEntry<K,V>)currentTable[nextTableIndex--]) != null)
4300	<	return;
4298	>	/**
4299	>	* Returns the result of accumulating the given transformation
4300	>	* of all entries using the given reducer to combine values,
4301	>	* and the given basis as an identity value.
4302	>	*
4303	>	* @param parallelismThreshold the (estimated) number of elements
4304	>	* needed for this operation to be executed in parallel
4305	>	* @param transformer a function returning the transformation
4306	>	* for an element
4307	>	* @param basis the identity (initial default value) for the reduction
4308	>	* @param reducer a commutative associative combining function
4309	>	* @return the result of accumulating the given transformation
4310	>	* of all entries
4311	>	* @since 1.8
4312	>	*/
4313	>	public double reduceEntriesToDouble(long parallelismThreshold,
4314	>	ToDoubleFunction<Map.Entry<K,V>> transformer,
4315	>	double basis,
4316	>	DoubleBinaryOperator reducer) {
4317	>	if (transformer == null || reducer == null)
4318	>	throw new NullPointerException();
4319	>	return new MapReduceEntriesToDoubleTask<K,V>
4320	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4321	>	null, transformer, basis, reducer).invoke();
4322	>	}
4323	>
4324	>	/**
4325	>	* Returns the result of accumulating the given transformation
4326	>	* of all entries using the given reducer to combine values,
4327	>	* and the given basis as an identity value.
4328	>	*
4329	>	* @param parallelismThreshold the (estimated) number of elements
4330	>	* needed for this operation to be executed in parallel
4331	>	* @param transformer a function returning the transformation
4332	>	* for an element
4333	>	* @param basis the identity (initial default value) for the reduction
4334	>	* @param reducer a commutative associative combining function
4335	>	* @return the result of accumulating the given transformation
4336	>	* of all entries
4337	>	* @since 1.8
4338	>	*/
4339	>	public long reduceEntriesToLong(long parallelismThreshold,
4340	>	ToLongFunction<Map.Entry<K,V>> transformer,
4341	>	long basis,
4342	>	LongBinaryOperator reducer) {
4343	>	if (transformer == null || reducer == null)
4344	>	throw new NullPointerException();
4345	>	return new MapReduceEntriesToLongTask<K,V>
4346	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4347	>	null, transformer, basis, reducer).invoke();
4348	>	}
4349	>
4350	>	/**
4351	>	* Returns the result of accumulating the given transformation
4352	>	* of all entries using the given reducer to combine values,
4353	>	* and the given basis as an identity value.
4354	>	*
4355	>	* @param parallelismThreshold the (estimated) number of elements
4356	>	* needed for this operation to be executed in parallel
4357	>	* @param transformer a function returning the transformation
4358	>	* for an element
4359	>	* @param basis the identity (initial default value) for the reduction
4360	>	* @param reducer a commutative associative combining function
4361	>	* @return the result of accumulating the given transformation
4362	>	* of all entries
4363	>	* @since 1.8
4364	>	*/
4365	>	public int reduceEntriesToInt(long parallelismThreshold,
4366	>	ToIntFunction<Map.Entry<K,V>> transformer,
4367	>	int basis,
4368	>	IntBinaryOperator reducer) {
4369	>	if (transformer == null || reducer == null)
4370	>	throw new NullPointerException();
4371	>	return new MapReduceEntriesToIntTask<K,V>
4372	>	(null, batchFor(parallelismThreshold), 0, 0, table,
4373	>	null, transformer, basis, reducer).invoke();
4374	>	}
4375	>
4376	>
4377	>	/* ----------------Views -------------- */
4378	>
4379	>	/**
4380	>	* Base class for views.
4381	>	*/
4382	>	abstract static class CollectionView<K,V,E>
4383	>	implements Collection<E>, java.io.Serializable {
4384	>	private static final long serialVersionUID = 7249069246763182397L;
4385	>	final ConcurrentHashMap<K,V> map;
4386	>	CollectionView(ConcurrentHashMap<K,V> map)  { this.map = map; }
4387	>
4388	>	/**
4389	>	* Returns the map backing this view.
4390	>	*
4391	>	* @return the map backing this view
4392	>	*/
4393	>	public ConcurrentHashMap<K,V> getMap() { return map; }
4394	>
4395	>	/**
4396	>	* Removes all of the elements from this view, by removing all
4397	>	* the mappings from the map backing this view.
4398	>	*/
4399	>	public final void clear()      { map.clear(); }
4400	>	public final int size()        { return map.size(); }
4401	>	public final boolean isEmpty() { return map.isEmpty(); }
4402	>
4403	>	// implementations below rely on concrete classes supplying these
4404	>	// abstract methods
4405	>	/**
4406	>	* Returns an iterator over the elements in this collection.
4407	>	*
4408	>	* <p>The returned iterator is
4409	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
4410	>	*
4411	>	* @return an iterator over the elements in this collection
4412	>	*/
4413	>	public abstract Iterator<E> iterator();
4414	>	public abstract boolean contains(Object o);
4415	>	public abstract boolean remove(Object o);
4416	>
4417	>	private static final String OOME_MSG = "Required array size too large";
4418	>
4419	>	public final Object[] toArray() {
4420	>	long sz = map.mappingCount();
4421	>	if (sz > MAX_ARRAY_SIZE)
4422	>	throw new OutOfMemoryError(OOME_MSG);
4423	>	int n = (int)sz;
4424	>	Object[] r = new Object[n];
4425	>	int i = 0;
4426	>	for (E e : this) {
4427	>	if (i == n) {
4428	>	if (n >= MAX_ARRAY_SIZE)
4429	>	throw new OutOfMemoryError(OOME_MSG);
4430	>	if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4431	>	n = MAX_ARRAY_SIZE;
4432	>	else
4433	>	n += (n >>> 1) + 1;
4434	>	r = Arrays.copyOf(r, n);
4435	>	}
4436	>	r[i++] = e;
4437		}
4438	+	return (i == n) ? r : Arrays.copyOf(r, i);
4439	+	}
4440
4441	<	while (nextSegmentIndex >= 0) {
4442	<	Segment<K,V> seg = (Segment<K,V>)segments[nextSegmentIndex--];
4443	<	if (seg.count != 0) {
4444	<	currentTable = seg.table;
4445	<	for (int j = currentTable.length - 1; j >= 0; --j) {
4446	<	if ( (nextEntry = (HashEntry<K,V>)currentTable[j]) != null) {
4447	<	nextTableIndex = j - 1;
4448	<	return;
4449	<	}
4450	<	}
4441	>	@SuppressWarnings("unchecked")
4442	>	public final <T> T[] toArray(T[] a) {
4443	>	long sz = map.mappingCount();
4444	>	if (sz > MAX_ARRAY_SIZE)
4445	>	throw new OutOfMemoryError(OOME_MSG);
4446	>	int m = (int)sz;
4447	>	T[] r = (a.length >= m) ? a :
4448	>	(T[])java.lang.reflect.Array
4449	>	.newInstance(a.getClass().getComponentType(), m);
4450	>	int n = r.length;
4451	>	int i = 0;
4452	>	for (E e : this) {
4453	>	if (i == n) {
4454	>	if (n >= MAX_ARRAY_SIZE)
4455	>	throw new OutOfMemoryError(OOME_MSG);
4456	>	if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
4457	>	n = MAX_ARRAY_SIZE;
4458	>	else
4459	>	n += (n >>> 1) + 1;
4460	>	r = Arrays.copyOf(r, n);
4461		}
4462	+	r[i++] = (T)e;
4463		}
4464	+	if (a == r && i < n) {
4465	+	r[i] = null; // null-terminate
4466	+	return r;
4467	+	}
4468	+	return (i == n) ? r : Arrays.copyOf(r, i);
4469		}
4470
4471	<	public boolean hasNext() { return nextEntry != null; }
4471	>	/**
4472	>	* Returns a string representation of this collection.
4473	>	* The string representation consists of the string representations
4474	>	* of the collection's elements in the order they are returned by
4475	>	* its iterator, enclosed in square brackets ({@code "[]"}).
4476	>	* Adjacent elements are separated by the characters {@code ", "}
4477	>	* (comma and space).  Elements are converted to strings as by
4478	>	* {@link String#valueOf(Object)}.
4479	>	*
4480	>	* @return a string representation of this collection
4481	>	*/
4482	>	public final String toString() {
4483	>	StringBuilder sb = new StringBuilder();
4484	>	sb.append('[');
4485	>	Iterator<E> it = iterator();
4486	>	if (it.hasNext()) {
4487	>	for (;;) {
4488	>	Object e = it.next();
4489	>	sb.append(e == this ? "(this Collection)" : e);
4490	>	if (!it.hasNext())
4491	>	break;
4492	>	sb.append(',').append(' ');
4493	>	}
4494	>	}
4495	>	return sb.append(']').toString();
4496	>	}
4497
4498	<	HashEntry<K,V> nextEntry() {
4499	<	if (nextEntry == null)
4500	<	throw new NoSuchElementException();
4501	<	lastReturned = nextEntry;
4502	<	advance();
4503	<	return lastReturned;
4498	>	public final boolean containsAll(Collection<?> c) {
4499	>	if (c != this) {
4500	>	for (Object e : c) {
4501	>	if (e == null || !contains(e))
4502	>	return false;
4503	>	}
4504	>	}
4505	>	return true;
4506		}
4507
4508	<	public void remove() {
4509	<	if (lastReturned == null)
4510	<	throw new IllegalStateException();
4511	<	ConcurrentHashMap.this.remove(lastReturned.key);
4512	<	lastReturned = null;
4508	>	public boolean removeAll(Collection<?> c) {
4509	>	if (c == null) throw new NullPointerException();
4510	>	boolean modified = false;
4511	>	// Use (c instanceof Set) as a hint that lookup in c is as
4512	>	// efficient as this view
4513	>	Node<K,V>[] t;
4514	>	if ((t = map.table) == null) {
4515	>	return false;
4516	>	} else if (c instanceof Set<?> && c.size() > t.length) {
4517	>	for (Iterator<?> it = iterator(); it.hasNext(); ) {
4518	>	if (c.contains(it.next())) {
4519	>	it.remove();
4520	>	modified = true;
4521	>	}
4522	>	}
4523	>	} else {
4524	>	for (Object e : c)
4525	>	modified |= remove(e);
4526	>	}
4527	>	return modified;
4528		}
1129	–	}
4529
4530	<	final class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> {
4531	<	public K next() { return super.nextEntry().key; }
4532	<	public K nextElement() { return super.nextEntry().key; }
4533	<	}
4530	>	public final boolean retainAll(Collection<?> c) {
4531	>	if (c == null) throw new NullPointerException();
4532	>	boolean modified = false;
4533	>	for (Iterator<E> it = iterator(); it.hasNext();) {
4534	>	if (!c.contains(it.next())) {
4535	>	it.remove();
4536	>	modified = true;
4537	>	}
4538	>	}
4539	>	return modified;
4540	>	}
4541
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; }
4542		}
4543
1141	–
1142	–
4544		/**
4545	<	* Entry iterator. Exported Entry objects must write-through
4546	<	* changes in setValue, even if the nodes have been cloned. So we
4547	<	* cannot return internal HashEntry objects. Instead, the iterator
4548	<	* itself acts as a forwarding pseudo-entry.
4545	>	* A view of a ConcurrentHashMap as a {@link Set} of keys, in
4546	>	* which additions may optionally be enabled by mapping to a
4547	>	* common value.  This class cannot be directly instantiated.
4548	>	* See {@link #keySet() keySet()},
4549	>	* {@link #keySet(Object) keySet(V)},
4550	>	* {@link #newKeySet() newKeySet()},
4551	>	* {@link #newKeySet(int) newKeySet(int)}.
4552	>	*
4553	>	* @since 1.8
4554		*/
4555	<	final class EntryIterator extends HashIterator implements Map.Entry<K,V>, Iterator<Entry<K,V>> {
4556	<	public Map.Entry<K,V> next() {
4557	<	nextEntry();
4558	<	return this;
4555	>	public static class KeySetView<K,V> extends CollectionView<K,V,K>
4556	>	implements Set<K>, java.io.Serializable {
4557	>	private static final long serialVersionUID = 7249069246763182397L;
4558	>	private final V value;
4559	>	KeySetView(ConcurrentHashMap<K,V> map, V value) {  // non-public
4560	>	super(map);
4561	>	this.value = value;
4562		}
4563
4564	<	public K getKey() {
4565	<	if (lastReturned == null)
4566	<	throw new IllegalStateException("Entry was removed");
4567	<	return lastReturned.key;
4564	>	/**
4565	>	* Returns the default mapped value for additions,
4566	>	* or {@code null} if additions are not supported.
4567	>	*
4568	>	* @return the default mapped value for additions, or {@code null}
4569	>	* if not supported
4570	>	*/
4571	>	public V getMappedValue() { return value; }
4572	>
4573	>	/**
4574	>	* {@inheritDoc}
4575	>	* @throws NullPointerException if the specified key is null
4576	>	*/
4577	>	public boolean contains(Object o) { return map.containsKey(o); }
4578	>
4579	>	/**
4580	>	* Removes the key from this map view, by removing the key (and its
4581	>	* corresponding value) from the backing map.  This method does
4582	>	* nothing if the key is not in the map.
4583	>	*
4584	>	* @param  o the key to be removed from the backing map
4585	>	* @return {@code true} if the backing map contained the specified key
4586	>	* @throws NullPointerException if the specified key is null
4587	>	*/
4588	>	public boolean remove(Object o) { return map.remove(o) != null; }
4589	>
4590	>	/**
4591	>	* @return an iterator over the keys of the backing map
4592	>	*/
4593	>	public Iterator<K> iterator() {
4594	>	Node<K,V>[] t;
4595	>	ConcurrentHashMap<K,V> m = map;
4596	>	int f = (t = m.table) == null ? 0 : t.length;
4597	>	return new KeyIterator<K,V>(t, f, 0, f, m);
4598		}
4599
4600	<	public V getValue() {
4601	<	if (lastReturned == null)
4602	<	throw new IllegalStateException("Entry was removed");
4603	<	return ConcurrentHashMap.this.get(lastReturned.key);
4600	>	/**
4601	>	* Adds the specified key to this set view by mapping the key to
4602	>	* the default mapped value in the backing map, if defined.
4603	>	*
4604	>	* @param e key to be added
4605	>	* @return {@code true} if this set changed as a result of the call
4606	>	* @throws NullPointerException if the specified key is null
4607	>	* @throws UnsupportedOperationException if no default mapped value
4608	>	* for additions was provided
4609	>	*/
4610	>	public boolean add(K e) {
4611	>	V v;
4612	>	if ((v = value) == null)
4613	>	throw new UnsupportedOperationException();
4614	>	return map.putVal(e, v, true) == null;
4615		}
4616
4617	<	public V setValue(V value) {
4618	<	if (lastReturned == null)
4619	<	throw new IllegalStateException("Entry was removed");
4620	<	return ConcurrentHashMap.this.put(lastReturned.key, value);
4617	>	/**
4618	>	* Adds all of the elements in the specified collection to this set,
4619	>	* as if by calling {@link #add} on each one.
4620	>	*
4621	>	* @param c the elements to be inserted into this set
4622	>	* @return {@code true} if this set changed as a result of the call
4623	>	* @throws NullPointerException if the collection or any of its
4624	>	* elements are {@code null}
4625	>	* @throws UnsupportedOperationException if no default mapped value
4626	>	* for additions was provided
4627	>	*/
4628	>	public boolean addAll(Collection<? extends K> c) {
4629	>	boolean added = false;
4630	>	V v;
4631	>	if ((v = value) == null)
4632	>	throw new UnsupportedOperationException();
4633	>	for (K e : c) {
4634	>	if (map.putVal(e, v, true) == null)
4635	>	added = true;
4636	>	}
4637	>	return added;
4638	>	}
4639	>
4640	>	public int hashCode() {
4641	>	int h = 0;
4642	>	for (K e : this)
4643	>	h += e.hashCode();
4644	>	return h;
4645		}
4646
4647		public boolean equals(Object o) {
4648	<	// If not acting as entry, just use default.
4649	<	if (lastReturned == null)
4650	<	return super.equals(o);
4651	<	if (!(o instanceof Map.Entry))
4652	<	return false;
4653	<	Map.Entry e = (Map.Entry)o;
4654	<	return eq(getKey(), e.getKey()) && eq(getValue(), e.getValue());
4648	>	Set<?> c;
4649	>	return ((o instanceof Set) &&
4650	>	((c = (Set<?>)o) == this ||
4651	>	(containsAll(c) && c.containsAll(this))));
4652	>	}
4653	>
4654	>	public Spliterator<K> spliterator() {
4655	>	Node<K,V>[] t;
4656	>	ConcurrentHashMap<K,V> m = map;
4657	>	long n = m.sumCount();
4658	>	int f = (t = m.table) == null ? 0 : t.length;
4659	>	return new KeySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4660	>	}
4661	>
4662	>	public void forEach(Consumer<? super K> action) {
4663	>	if (action == null) throw new NullPointerException();
4664	>	Node<K,V>[] t;
4665	>	if ((t = map.table) != null) {
4666	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4667	>	for (Node<K,V> p; (p = it.advance()) != null; )
4668	>	action.accept(p.key);
4669	>	}
4670		}
4671	+	}
4672
4673	<	public int hashCode() {
4674	<	// If not acting as entry, just use default.
4675	<	if (lastReturned == null)
4676	<	return super.hashCode();
4677	<
4678	<	Object k = getKey();
4679	<	Object v = getValue();
4680	<	return ((k == null) ? 0 : k.hashCode()) ^
4681	<	((v == null) ? 0 : v.hashCode());
4673	>	/**
4674	>	* A view of a ConcurrentHashMap as a {@link Collection} of
4675	>	* values, in which additions are disabled. This class cannot be
4676	>	* directly instantiated. See {@link #values()}.
4677	>	*/
4678	>	static final class ValuesView<K,V> extends CollectionView<K,V,V>
4679	>	implements Collection<V>, java.io.Serializable {
4680	>	private static final long serialVersionUID = 2249069246763182397L;
4681	>	ValuesView(ConcurrentHashMap<K,V> map) { super(map); }
4682	>	public final boolean contains(Object o) {
4683	>	return map.containsValue(o);
4684		}
4685
4686	<	public String toString() {
4687	<	// If not acting as entry, just use default.
4688	<	if (lastReturned == null)
4689	<	return super.toString();
4690	<	else
4691	<	return getKey() + "=" + getValue();
4686	>	public final boolean remove(Object o) {
4687	>	if (o != null) {
4688	>	for (Iterator<V> it = iterator(); it.hasNext();) {
4689	>	if (o.equals(it.next())) {
4690	>	it.remove();
4691	>	return true;
4692	>	}
4693	>	}
4694	>	}
4695	>	return false;
4696		}
4697
4698	<	boolean eq(Object o1, Object o2) {
4699	<	return (o1 == null ? o2 == null : o1.equals(o2));
4698	>	public final Iterator<V> iterator() {
4699	>	ConcurrentHashMap<K,V> m = map;
4700	>	Node<K,V>[] t;
4701	>	int f = (t = m.table) == null ? 0 : t.length;
4702	>	return new ValueIterator<K,V>(t, f, 0, f, m);
4703	>	}
4704	>
4705	>	public final boolean add(V e) {
4706	>	throw new UnsupportedOperationException();
4707	>	}
4708	>	public final boolean addAll(Collection<? extends V> c) {
4709	>	throw new UnsupportedOperationException();
4710	>	}
4711	>
4712	>	@Override public boolean removeAll(Collection<?> c) {
4713	>	if (c == null) throw new NullPointerException();
4714	>	boolean modified = false;
4715	>	for (Iterator<V> it = iterator(); it.hasNext();) {
4716	>	if (c.contains(it.next())) {
4717	>	it.remove();
4718	>	modified = true;
4719	>	}
4720	>	}
4721	>	return modified;
4722		}
4723
4724	<	}
4724	>	public boolean removeIf(Predicate<? super V> filter) {
4725	>	return map.removeValueIf(filter);
4726	>	}
4727
4728	<	final class KeySet extends AbstractSet<K> {
4729	<	public Iterator<K> iterator() {
4730	<	return new KeyIterator();
4728	>	public Spliterator<V> spliterator() {
4729	>	Node<K,V>[] t;
4730	>	ConcurrentHashMap<K,V> m = map;
4731	>	long n = m.sumCount();
4732	>	int f = (t = m.table) == null ? 0 : t.length;
4733	>	return new ValueSpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n);
4734		}
4735	<	public int size() {
4736	<	return ConcurrentHashMap.this.size();
4735	>
4736	>	public void forEach(Consumer<? super V> action) {
4737	>	if (action == null) throw new NullPointerException();
4738	>	Node<K,V>[] t;
4739	>	if ((t = map.table) != null) {
4740	>	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4741	>	for (Node<K,V> p; (p = it.advance()) != null; )
4742	>	action.accept(p.val);
4743	>	}
4744		}
4745	+	}
4746	+
4747	+	/**
4748	+	* A view of a ConcurrentHashMap as a {@link Set} of (key, value)
4749	+	* entries.  This class cannot be directly instantiated. See
4750	+	* {@link #entrySet()}.
4751	+	*/
4752	+	static final class EntrySetView<K,V> extends CollectionView<K,V,Map.Entry<K,V>>
4753	+	implements Set<Map.Entry<K,V>>, java.io.Serializable {
4754	+	private static final long serialVersionUID = 2249069246763182397L;
4755	+	EntrySetView(ConcurrentHashMap<K,V> map) { super(map); }
4756	+
4757		public boolean contains(Object o) {
4758	<	return ConcurrentHashMap.this.containsKey(o);
4758	>	Object k, v, r; Map.Entry<?,?> e;
4759	>	return ((o instanceof Map.Entry) &&
4760	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4761	>	(r = map.get(k)) != null &&
4762	>	(v = e.getValue()) != null &&
4763	>	(v == r || v.equals(r)));
4764		}
4765	+
4766		public boolean remove(Object o) {
4767	<	return ConcurrentHashMap.this.remove(o) != null;
4767	>	Object k, v; Map.Entry<?,?> e;
4768	>	return ((o instanceof Map.Entry) &&
4769	>	(k = (e = (Map.Entry<?,?>)o).getKey()) != null &&
4770	>	(v = e.getValue()) != null &&
4771	>	map.remove(k, v));
4772		}
4773	<	public void clear() {
4774	<	ConcurrentHashMap.this.clear();
4773	>
4774	>	/**
4775	>	* @return an iterator over the entries of the backing map
4776	>	*/
4777	>	public Iterator<Map.Entry<K,V>> iterator() {
4778	>	ConcurrentHashMap<K,V> m = map;
4779	>	Node<K,V>[] t;
4780	>	int f = (t = m.table) == null ? 0 : t.length;
4781	>	return new EntryIterator<K,V>(t, f, 0, f, m);
4782		}
4783	<	public Object[] toArray() {
4784	<	Collection<K> c = new ArrayList<K>();
4785	<	for (Iterator<K> i = iterator(); i.hasNext(); )
1227	<	c.add(i.next());
1228	<	return c.toArray();
4783	>
4784	>	public boolean add(Entry<K,V> e) {
4785	>	return map.putVal(e.getKey(), e.getValue(), false) == null;
4786		}
4787	<	public <T> T[] toArray(T[] a) {
4788	<	Collection<K> c = new ArrayList<K>();
4789	<	for (Iterator<K> i = iterator(); i.hasNext(); )
4790	<	c.add(i.next());
4791	<	return c.toArray(a);
4787	>
4788	>	public boolean addAll(Collection<? extends Entry<K,V>> c) {
4789	>	boolean added = false;
4790	>	for (Entry<K,V> e : c) {
4791	>	if (add(e))
4792	>	added = true;
4793	>	}
4794	>	return added;
4795		}
4796	+
4797	+	public boolean removeIf(Predicate<? super Entry<K,V>> filter) {
4798	+	return map.removeEntryIf(filter);
4799	+	}
4800	+
4801	+	public final int hashCode() {
4802	+	int h = 0;
4803	+	Node<K,V>[] t;
4804	+	if ((t = map.table) != null) {
4805	+	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4806	+	for (Node<K,V> p; (p = it.advance()) != null; ) {
4807	+	h += p.hashCode();
4808	+	}
4809	+	}
4810	+	return h;
4811	+	}
4812	+
4813	+	public final boolean equals(Object o) {
4814	+	Set<?> c;
4815	+	return ((o instanceof Set) &&
4816	+	((c = (Set<?>)o) == this ||
4817	+	(containsAll(c) && c.containsAll(this))));
4818	+	}
4819	+
4820	+	public Spliterator<Map.Entry<K,V>> spliterator() {
4821	+	Node<K,V>[] t;
4822	+	ConcurrentHashMap<K,V> m = map;
4823	+	long n = m.sumCount();
4824	+	int f = (t = m.table) == null ? 0 : t.length;
4825	+	return new EntrySpliterator<K,V>(t, f, 0, f, n < 0L ? 0L : n, m);
4826	+	}
4827	+
4828	+	public void forEach(Consumer<? super Map.Entry<K,V>> action) {
4829	+	if (action == null) throw new NullPointerException();
4830	+	Node<K,V>[] t;
4831	+	if ((t = map.table) != null) {
4832	+	Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length);
4833	+	for (Node<K,V> p; (p = it.advance()) != null; )
4834	+	action.accept(new MapEntry<K,V>(p.key, p.val, map));
4835	+	}
4836	+	}
4837	+
4838		}
4839
4840	<	final class Values extends AbstractCollection<V> {
4841	<	public Iterator<V> iterator() {
4842	<	return new ValueIterator();
4840	>	// -------------------------------------------------------
4841	>
4842	>	/**
4843	>	* Base class for bulk tasks. Repeats some fields and code from
4844	>	* class Traverser, because we need to subclass CountedCompleter.
4845	>	*/
4846	>	@SuppressWarnings("serial")
4847	>	abstract static class BulkTask<K,V,R> extends CountedCompleter<R> {
4848	>	Node<K,V>[] tab;        // same as Traverser
4849	>	Node<K,V> next;
4850	>	TableStack<K,V> stack, spare;
4851	>	int index;
4852	>	int baseIndex;
4853	>	int baseLimit;
4854	>	final int baseSize;
4855	>	int batch;              // split control
4856	>
4857	>	BulkTask(BulkTask<K,V,?> par, int b, int i, int f, Node<K,V>[] t) {
4858	>	super(par);
4859	>	this.batch = b;
4860	>	this.index = this.baseIndex = i;
4861	>	if ((this.tab = t) == null)
4862	>	this.baseSize = this.baseLimit = 0;
4863	>	else if (par == null)
4864	>	this.baseSize = this.baseLimit = t.length;
4865	>	else {
4866	>	this.baseLimit = f;
4867	>	this.baseSize = par.baseSize;
4868	>	}
4869		}
4870	<	public int size() {
4871	<	return ConcurrentHashMap.this.size();
4870	>
4871	>	/**
4872	>	* Same as Traverser version.
4873	>	*/
4874	>	final Node<K,V> advance() {
4875	>	Node<K,V> e;
4876	>	if ((e = next) != null)
4877	>	e = e.next;
4878	>	for (;;) {
4879	>	Node<K,V>[] t; int i, n;
4880	>	if (e != null)
4881	>	return next = e;
4882	>	if (baseIndex >= baseLimit || (t = tab) == null ||
4883	>	(n = t.length) <= (i = index) || i < 0)
4884	>	return next = null;
4885	>	if ((e = tabAt(t, i)) != null && e.hash < 0) {
4886	>	if (e instanceof ForwardingNode) {
4887	>	tab = ((ForwardingNode<K,V>)e).nextTable;
4888	>	e = null;
4889	>	pushState(t, i, n);
4890	>	continue;
4891	>	}
4892	>	else if (e instanceof TreeBin)
4893	>	e = ((TreeBin<K,V>)e).first;
4894	>	else
4895	>	e = null;
4896	>	}
4897	>	if (stack != null)
4898	>	recoverState(n);
4899	>	else if ((index = i + baseSize) >= n)
4900	>	index = ++baseIndex;
4901	>	}
4902		}
4903	<	public boolean contains(Object o) {
4904	<	return ConcurrentHashMap.this.containsValue(o);
4903	>
4904	>	private void pushState(Node<K,V>[] t, int i, int n) {
4905	>	TableStack<K,V> s = spare;
4906	>	if (s != null)
4907	>	spare = s.next;
4908	>	else
4909	>	s = new TableStack<K,V>();
4910	>	s.tab = t;
4911	>	s.length = n;
4912	>	s.index = i;
4913	>	s.next = stack;
4914	>	stack = s;
4915	>	}
4916	>
4917	>	private void recoverState(int n) {
4918	>	TableStack<K,V> s; int len;
4919	>	while ((s = stack) != null && (index += (len = s.length)) >= n) {
4920	>	n = len;
4921	>	index = s.index;
4922	>	tab = s.tab;
4923	>	s.tab = null;
4924	>	TableStack<K,V> next = s.next;
4925	>	s.next = spare; // save for reuse
4926	>	stack = next;
4927	>	spare = s;
4928	>	}
4929	>	if (s == null && (index += baseSize) >= n)
4930	>	index = ++baseIndex;
4931		}
4932	<	public void clear() {
4933	<	ConcurrentHashMap.this.clear();
4932	>	}
4933	>
4934	>	/*
4935	>	* Task classes. Coded in a regular but ugly format/style to
4936	>	* simplify checks that each variant differs in the right way from
4937	>	* others. The null screenings exist because compilers cannot tell
4938	>	* that we've already null-checked task arguments, so we force
4939	>	* simplest hoisted bypass to help avoid convoluted traps.
4940	>	*/
4941	>	@SuppressWarnings("serial")
4942	>	static final class ForEachKeyTask<K,V>
4943	>	extends BulkTask<K,V,Void> {
4944	>	final Consumer<? super K> action;
4945	>	ForEachKeyTask
4946	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4947	>	Consumer<? super K> action) {
4948	>	super(p, b, i, f, t);
4949	>	this.action = action;
4950	>	}
4951	>	public final void compute() {
4952	>	final Consumer<? super K> action;
4953	>	if ((action = this.action) != null) {
4954	>	for (int i = baseIndex, f, h; batch > 0 &&
4955	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4956	>	addToPendingCount(1);
4957	>	new ForEachKeyTask<K,V>
4958	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4959	>	action).fork();
4960	>	}
4961	>	for (Node<K,V> p; (p = advance()) != null;)
4962	>	action.accept(p.key);
4963	>	propagateCompletion();
4964	>	}
4965		}
4966	<	public Object[] toArray() {
4967	<	Collection<V> c = new ArrayList<V>();
4968	<	for (Iterator<V> i = iterator(); i.hasNext(); )
4969	<	c.add(i.next());
4970	<	return c.toArray();
4966	>	}
4967	>
4968	>	@SuppressWarnings("serial")
4969	>	static final class ForEachValueTask<K,V>
4970	>	extends BulkTask<K,V,Void> {
4971	>	final Consumer<? super V> action;
4972	>	ForEachValueTask
4973	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
4974	>	Consumer<? super V> action) {
4975	>	super(p, b, i, f, t);
4976	>	this.action = action;
4977	>	}
4978	>	public final void compute() {
4979	>	final Consumer<? super V> action;
4980	>	if ((action = this.action) != null) {
4981	>	for (int i = baseIndex, f, h; batch > 0 &&
4982	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
4983	>	addToPendingCount(1);
4984	>	new ForEachValueTask<K,V>
4985	>	(this, batch >>>= 1, baseLimit = h, f, tab,
4986	>	action).fork();
4987	>	}
4988	>	for (Node<K,V> p; (p = advance()) != null;)
4989	>	action.accept(p.val);
4990	>	propagateCompletion();
4991	>	}
4992		}
4993	<	public <T> T[] toArray(T[] a) {
4994	<	Collection<V> c = new ArrayList<V>();
4995	<	for (Iterator<V> i = iterator(); i.hasNext(); )
4996	<	c.add(i.next());
4997	<	return c.toArray(a);
4993	>	}
4994	>
4995	>	@SuppressWarnings("serial")
4996	>	static final class ForEachEntryTask<K,V>
4997	>	extends BulkTask<K,V,Void> {
4998	>	final Consumer<? super Entry<K,V>> action;
4999	>	ForEachEntryTask
5000	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5001	>	Consumer<? super Entry<K,V>> action) {
5002	>	super(p, b, i, f, t);
5003	>	this.action = action;
5004	>	}
5005	>	public final void compute() {
5006	>	final Consumer<? super Entry<K,V>> action;
5007	>	if ((action = this.action) != null) {
5008	>	for (int i = baseIndex, f, h; batch > 0 &&
5009	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5010	>	addToPendingCount(1);
5011	>	new ForEachEntryTask<K,V>
5012	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5013	>	action).fork();
5014	>	}
5015	>	for (Node<K,V> p; (p = advance()) != null; )
5016	>	action.accept(p);
5017	>	propagateCompletion();
5018	>	}
5019		}
5020		}
5021
5022	<	final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
5023	<	public Iterator<Map.Entry<K,V>> iterator() {
5024	<	return new EntryIterator();
5022	>	@SuppressWarnings("serial")
5023	>	static final class ForEachMappingTask<K,V>
5024	>	extends BulkTask<K,V,Void> {
5025	>	final BiConsumer<? super K, ? super V> action;
5026	>	ForEachMappingTask
5027	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5028	>	BiConsumer<? super K,? super V> action) {
5029	>	super(p, b, i, f, t);
5030	>	this.action = action;
5031	>	}
5032	>	public final void compute() {
5033	>	final BiConsumer<? super K, ? super V> action;
5034	>	if ((action = this.action) != null) {
5035	>	for (int i = baseIndex, f, h; batch > 0 &&
5036	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5037	>	addToPendingCount(1);
5038	>	new ForEachMappingTask<K,V>
5039	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5040	>	action).fork();
5041	>	}
5042	>	for (Node<K,V> p; (p = advance()) != null; )
5043	>	action.accept(p.key, p.val);
5044	>	propagateCompletion();
5045	>	}
5046		}
5047	<	public boolean contains(Object o) {
5048	<	if (!(o instanceof Map.Entry))
5049	<	return false;
5050	<	Map.Entry<K,V> e = (Map.Entry<K,V>)o;
5051	<	V v = ConcurrentHashMap.this.get(e.getKey());
5052	<	return v != null && v.equals(e.getValue());
5047	>	}
5048	>
5049	>	@SuppressWarnings("serial")
5050	>	static final class ForEachTransformedKeyTask<K,V,U>
5051	>	extends BulkTask<K,V,Void> {
5052	>	final Function<? super K, ? extends U> transformer;
5053	>	final Consumer<? super U> action;
5054	>	ForEachTransformedKeyTask
5055	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5056	>	Function<? super K, ? extends U> transformer, Consumer<? super U> action) {
5057	>	super(p, b, i, f, t);
5058	>	this.transformer = transformer; this.action = action;
5059	>	}
5060	>	public final void compute() {
5061	>	final Function<? super K, ? extends U> transformer;
5062	>	final Consumer<? super U> action;
5063	>	if ((transformer = this.transformer) != null &&
5064	>	(action = this.action) != null) {
5065	>	for (int i = baseIndex, f, h; batch > 0 &&
5066	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5067	>	addToPendingCount(1);
5068	>	new ForEachTransformedKeyTask<K,V,U>
5069	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5070	>	transformer, action).fork();
5071	>	}
5072	>	for (Node<K,V> p; (p = advance()) != null; ) {
5073	>	U u;
5074	>	if ((u = transformer.apply(p.key)) != null)
5075	>	action.accept(u);
5076	>	}
5077	>	propagateCompletion();
5078	>	}
5079		}
5080	<	public boolean remove(Object o) {
5081	<	if (!(o instanceof Map.Entry))
5082	<	return false;
5083	<	Map.Entry<K,V> e = (Map.Entry<K,V>)o;
5084	<	return ConcurrentHashMap.this.remove(e.getKey(), e.getValue());
5080	>	}
5081	>
5082	>	@SuppressWarnings("serial")
5083	>	static final class ForEachTransformedValueTask<K,V,U>
5084	>	extends BulkTask<K,V,Void> {
5085	>	final Function<? super V, ? extends U> transformer;
5086	>	final Consumer<? super U> action;
5087	>	ForEachTransformedValueTask
5088	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5089	>	Function<? super V, ? extends U> transformer, Consumer<? super U> action) {
5090	>	super(p, b, i, f, t);
5091	>	this.transformer = transformer; this.action = action;
5092	>	}
5093	>	public final void compute() {
5094	>	final Function<? super V, ? extends U> transformer;
5095	>	final Consumer<? super U> action;
5096	>	if ((transformer = this.transformer) != null &&
5097	>	(action = this.action) != null) {
5098	>	for (int i = baseIndex, f, h; batch > 0 &&
5099	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5100	>	addToPendingCount(1);
5101	>	new ForEachTransformedValueTask<K,V,U>
5102	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5103	>	transformer, action).fork();
5104	>	}
5105	>	for (Node<K,V> p; (p = advance()) != null; ) {
5106	>	U u;
5107	>	if ((u = transformer.apply(p.val)) != null)
5108	>	action.accept(u);
5109	>	}
5110	>	propagateCompletion();
5111	>	}
5112		}
5113	<	public int size() {
5114	<	return ConcurrentHashMap.this.size();
5113	>	}
5114	>
5115	>	@SuppressWarnings("serial")
5116	>	static final class ForEachTransformedEntryTask<K,V,U>
5117	>	extends BulkTask<K,V,Void> {
5118	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5119	>	final Consumer<? super U> action;
5120	>	ForEachTransformedEntryTask
5121	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5122	>	Function<Map.Entry<K,V>, ? extends U> transformer, Consumer<? super U> action) {
5123	>	super(p, b, i, f, t);
5124	>	this.transformer = transformer; this.action = action;
5125	>	}
5126	>	public final void compute() {
5127	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5128	>	final Consumer<? super U> action;
5129	>	if ((transformer = this.transformer) != null &&
5130	>	(action = this.action) != null) {
5131	>	for (int i = baseIndex, f, h; batch > 0 &&
5132	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5133	>	addToPendingCount(1);
5134	>	new ForEachTransformedEntryTask<K,V,U>
5135	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5136	>	transformer, action).fork();
5137	>	}
5138	>	for (Node<K,V> p; (p = advance()) != null; ) {
5139	>	U u;
5140	>	if ((u = transformer.apply(p)) != null)
5141	>	action.accept(u);
5142	>	}
5143	>	propagateCompletion();
5144	>	}
5145		}
5146	<	public void clear() {
5147	<	ConcurrentHashMap.this.clear();
5146	>	}
5147	>
5148	>	@SuppressWarnings("serial")
5149	>	static final class ForEachTransformedMappingTask<K,V,U>
5150	>	extends BulkTask<K,V,Void> {
5151	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5152	>	final Consumer<? super U> action;
5153	>	ForEachTransformedMappingTask
5154	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5155	>	BiFunction<? super K, ? super V, ? extends U> transformer,
5156	>	Consumer<? super U> action) {
5157	>	super(p, b, i, f, t);
5158	>	this.transformer = transformer; this.action = action;
5159	>	}
5160	>	public final void compute() {
5161	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5162	>	final Consumer<? super U> action;
5163	>	if ((transformer = this.transformer) != null &&
5164	>	(action = this.action) != null) {
5165	>	for (int i = baseIndex, f, h; batch > 0 &&
5166	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5167	>	addToPendingCount(1);
5168	>	new ForEachTransformedMappingTask<K,V,U>
5169	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5170	>	transformer, action).fork();
5171	>	}
5172	>	for (Node<K,V> p; (p = advance()) != null; ) {
5173	>	U u;
5174	>	if ((u = transformer.apply(p.key, p.val)) != null)
5175	>	action.accept(u);
5176	>	}
5177	>	propagateCompletion();
5178	>	}
5179		}
5180	<	public Object[] toArray() {
5181	<	// Since we don't ordinarily have distinct Entry objects, we
5182	<	// must pack elements using exportable SimpleEntry
5183	<	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
5184	<	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
5185	<	c.add(new SimpleEntry<K,V>(i.next()));
5186	<	return c.toArray();
5180	>	}
5181	>
5182	>	@SuppressWarnings("serial")
5183	>	static final class SearchKeysTask<K,V,U>
5184	>	extends BulkTask<K,V,U> {
5185	>	final Function<? super K, ? extends U> searchFunction;
5186	>	final AtomicReference<U> result;
5187	>	SearchKeysTask
5188	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5189	>	Function<? super K, ? extends U> searchFunction,
5190	>	AtomicReference<U> result) {
5191	>	super(p, b, i, f, t);
5192	>	this.searchFunction = searchFunction; this.result = result;
5193	>	}
5194	>	public final U getRawResult() { return result.get(); }
5195	>	public final void compute() {
5196	>	final Function<? super K, ? extends U> searchFunction;
5197	>	final AtomicReference<U> result;
5198	>	if ((searchFunction = this.searchFunction) != null &&
5199	>	(result = this.result) != null) {
5200	>	for (int i = baseIndex, f, h; batch > 0 &&
5201	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5202	>	if (result.get() != null)
5203	>	return;
5204	>	addToPendingCount(1);
5205	>	new SearchKeysTask<K,V,U>
5206	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5207	>	searchFunction, result).fork();
5208	>	}
5209	>	while (result.get() == null) {
5210	>	U u;
5211	>	Node<K,V> p;
5212	>	if ((p = advance()) == null) {
5213	>	propagateCompletion();
5214	>	break;
5215	>	}
5216	>	if ((u = searchFunction.apply(p.key)) != null) {
5217	>	if (result.compareAndSet(null, u))
5218	>	quietlyCompleteRoot();
5219	>	break;
5220	>	}
5221	>	}
5222	>	}
5223		}
5224	<	public <T> T[] toArray(T[] a) {
5225	<	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
5226	<	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
5227	<	c.add(new SimpleEntry<K,V>(i.next()));
5228	<	return c.toArray(a);
5224	>	}
5225	>
5226	>	@SuppressWarnings("serial")
5227	>	static final class SearchValuesTask<K,V,U>
5228	>	extends BulkTask<K,V,U> {
5229	>	final Function<? super V, ? extends U> searchFunction;
5230	>	final AtomicReference<U> result;
5231	>	SearchValuesTask
5232	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5233	>	Function<? super V, ? extends U> searchFunction,
5234	>	AtomicReference<U> result) {
5235	>	super(p, b, i, f, t);
5236	>	this.searchFunction = searchFunction; this.result = result;
5237	>	}
5238	>	public final U getRawResult() { return result.get(); }
5239	>	public final void compute() {
5240	>	final Function<? super V, ? extends U> searchFunction;
5241	>	final AtomicReference<U> result;
5242	>	if ((searchFunction = this.searchFunction) != null &&
5243	>	(result = this.result) != null) {
5244	>	for (int i = baseIndex, f, h; batch > 0 &&
5245	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5246	>	if (result.get() != null)
5247	>	return;
5248	>	addToPendingCount(1);
5249	>	new SearchValuesTask<K,V,U>
5250	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5251	>	searchFunction, result).fork();
5252	>	}
5253	>	while (result.get() == null) {
5254	>	U u;
5255	>	Node<K,V> p;
5256	>	if ((p = advance()) == null) {
5257	>	propagateCompletion();
5258	>	break;
5259	>	}
5260	>	if ((u = searchFunction.apply(p.val)) != null) {
5261	>	if (result.compareAndSet(null, u))
5262	>	quietlyCompleteRoot();
5263	>	break;
5264	>	}
5265	>	}
5266	>	}
5267		}
5268	+	}
5269
5270	+	@SuppressWarnings("serial")
5271	+	static final class SearchEntriesTask<K,V,U>
5272	+	extends BulkTask<K,V,U> {
5273	+	final Function<Entry<K,V>, ? extends U> searchFunction;
5274	+	final AtomicReference<U> result;
5275	+	SearchEntriesTask
5276	+	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5277	+	Function<Entry<K,V>, ? extends U> searchFunction,
5278	+	AtomicReference<U> result) {
5279	+	super(p, b, i, f, t);
5280	+	this.searchFunction = searchFunction; this.result = result;
5281	+	}
5282	+	public final U getRawResult() { return result.get(); }
5283	+	public final void compute() {
5284	+	final Function<Entry<K,V>, ? extends U> searchFunction;
5285	+	final AtomicReference<U> result;
5286	+	if ((searchFunction = this.searchFunction) != null &&
5287	+	(result = this.result) != null) {
5288	+	for (int i = baseIndex, f, h; batch > 0 &&
5289	+	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5290	+	if (result.get() != null)
5291	+	return;
5292	+	addToPendingCount(1);
5293	+	new SearchEntriesTask<K,V,U>
5294	+	(this, batch >>>= 1, baseLimit = h, f, tab,
5295	+	searchFunction, result).fork();
5296	+	}
5297	+	while (result.get() == null) {
5298	+	U u;
5299	+	Node<K,V> p;
5300	+	if ((p = advance()) == null) {
5301	+	propagateCompletion();
5302	+	break;
5303	+	}
5304	+	if ((u = searchFunction.apply(p)) != null) {
5305	+	if (result.compareAndSet(null, u))
5306	+	quietlyCompleteRoot();
5307	+	return;
5308	+	}
5309	+	}
5310	+	}
5311	+	}
5312		}
5313
5314	<	/**
5315	<	* This duplicates java.util.AbstractMap.SimpleEntry until this class
5316	<	* is made accessible.
5317	<	*/
5318	<	static final class SimpleEntry<K,V> implements Entry<K,V> {
5319	<	K key;
5320	<	V value;
5314	>	@SuppressWarnings("serial")
5315	>	static final class SearchMappingsTask<K,V,U>
5316	>	extends BulkTask<K,V,U> {
5317	>	final BiFunction<? super K, ? super V, ? extends U> searchFunction;
5318	>	final AtomicReference<U> result;
5319	>	SearchMappingsTask
5320	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5321	>	BiFunction<? super K, ? super V, ? extends U> searchFunction,
5322	>	AtomicReference<U> result) {
5323	>	super(p, b, i, f, t);
5324	>	this.searchFunction = searchFunction; this.result = result;
5325	>	}
5326	>	public final U getRawResult() { return result.get(); }
5327	>	public final void compute() {
5328	>	final BiFunction<? super K, ? super V, ? extends U> searchFunction;
5329	>	final AtomicReference<U> result;
5330	>	if ((searchFunction = this.searchFunction) != null &&
5331	>	(result = this.result) != null) {
5332	>	for (int i = baseIndex, f, h; batch > 0 &&
5333	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5334	>	if (result.get() != null)
5335	>	return;
5336	>	addToPendingCount(1);
5337	>	new SearchMappingsTask<K,V,U>
5338	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5339	>	searchFunction, result).fork();
5340	>	}
5341	>	while (result.get() == null) {
5342	>	U u;
5343	>	Node<K,V> p;
5344	>	if ((p = advance()) == null) {
5345	>	propagateCompletion();
5346	>	break;
5347	>	}
5348	>	if ((u = searchFunction.apply(p.key, p.val)) != null) {
5349	>	if (result.compareAndSet(null, u))
5350	>	quietlyCompleteRoot();
5351	>	break;
5352	>	}
5353	>	}
5354	>	}
5355	>	}
5356	>	}
5357
5358	<	public SimpleEntry(K key, V value) {
5359	<	this.key   = key;
5360	<	this.value = value;
5358	>	@SuppressWarnings("serial")
5359	>	static final class ReduceKeysTask<K,V>
5360	>	extends BulkTask<K,V,K> {
5361	>	final BiFunction<? super K, ? super K, ? extends K> reducer;
5362	>	K result;
5363	>	ReduceKeysTask<K,V> rights, nextRight;
5364	>	ReduceKeysTask
5365	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5366	>	ReduceKeysTask<K,V> nextRight,
5367	>	BiFunction<? super K, ? super K, ? extends K> reducer) {
5368	>	super(p, b, i, f, t); this.nextRight = nextRight;
5369	>	this.reducer = reducer;
5370	>	}
5371	>	public final K getRawResult() { return result; }
5372	>	public final void compute() {
5373	>	final BiFunction<? super K, ? super K, ? extends K> reducer;
5374	>	if ((reducer = this.reducer) != null) {
5375	>	for (int i = baseIndex, f, h; batch > 0 &&
5376	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5377	>	addToPendingCount(1);
5378	>	(rights = new ReduceKeysTask<K,V>
5379	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5380	>	rights, reducer)).fork();
5381	>	}
5382	>	K r = null;
5383	>	for (Node<K,V> p; (p = advance()) != null; ) {
5384	>	K u = p.key;
5385	>	r = (r == null) ? u : u == null ? r : reducer.apply(r, u);
5386	>	}
5387	>	result = r;
5388	>	CountedCompleter<?> c;
5389	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5390	>	@SuppressWarnings("unchecked")
5391	>	ReduceKeysTask<K,V>
5392	>	t = (ReduceKeysTask<K,V>)c,
5393	>	s = t.rights;
5394	>	while (s != null) {
5395	>	K tr, sr;
5396	>	if ((sr = s.result) != null)
5397	>	t.result = (((tr = t.result) == null) ? sr :
5398	>	reducer.apply(tr, sr));
5399	>	s = t.rights = s.nextRight;
5400	>	}
5401	>	}
5402	>	}
5403		}
5404	+	}
5405
5406	<	public SimpleEntry(Entry<K,V> e) {
5407	<	this.key   = e.getKey();
5408	<	this.value = e.getValue();
5406	>	@SuppressWarnings("serial")
5407	>	static final class ReduceValuesTask<K,V>
5408	>	extends BulkTask<K,V,V> {
5409	>	final BiFunction<? super V, ? super V, ? extends V> reducer;
5410	>	V result;
5411	>	ReduceValuesTask<K,V> rights, nextRight;
5412	>	ReduceValuesTask
5413	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5414	>	ReduceValuesTask<K,V> nextRight,
5415	>	BiFunction<? super V, ? super V, ? extends V> reducer) {
5416	>	super(p, b, i, f, t); this.nextRight = nextRight;
5417	>	this.reducer = reducer;
5418	>	}
5419	>	public final V getRawResult() { return result; }
5420	>	public final void compute() {
5421	>	final BiFunction<? super V, ? super V, ? extends V> reducer;
5422	>	if ((reducer = this.reducer) != null) {
5423	>	for (int i = baseIndex, f, h; batch > 0 &&
5424	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5425	>	addToPendingCount(1);
5426	>	(rights = new ReduceValuesTask<K,V>
5427	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5428	>	rights, reducer)).fork();
5429	>	}
5430	>	V r = null;
5431	>	for (Node<K,V> p; (p = advance()) != null; ) {
5432	>	V v = p.val;
5433	>	r = (r == null) ? v : reducer.apply(r, v);
5434	>	}
5435	>	result = r;
5436	>	CountedCompleter<?> c;
5437	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5438	>	@SuppressWarnings("unchecked")
5439	>	ReduceValuesTask<K,V>
5440	>	t = (ReduceValuesTask<K,V>)c,
5441	>	s = t.rights;
5442	>	while (s != null) {
5443	>	V tr, sr;
5444	>	if ((sr = s.result) != null)
5445	>	t.result = (((tr = t.result) == null) ? sr :
5446	>	reducer.apply(tr, sr));
5447	>	s = t.rights = s.nextRight;
5448	>	}
5449	>	}
5450	>	}
5451		}
5452	+	}
5453
5454	<	public K getKey() {
5455	<	return key;
5454	>	@SuppressWarnings("serial")
5455	>	static final class ReduceEntriesTask<K,V>
5456	>	extends BulkTask<K,V,Map.Entry<K,V>> {
5457	>	final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5458	>	Map.Entry<K,V> result;
5459	>	ReduceEntriesTask<K,V> rights, nextRight;
5460	>	ReduceEntriesTask
5461	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5462	>	ReduceEntriesTask<K,V> nextRight,
5463	>	BiFunction<Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer) {
5464	>	super(p, b, i, f, t); this.nextRight = nextRight;
5465	>	this.reducer = reducer;
5466	>	}
5467	>	public final Map.Entry<K,V> getRawResult() { return result; }
5468	>	public final void compute() {
5469	>	final BiFunction<Map.Entry<K,V>, Map.Entry<K,V>, ? extends Map.Entry<K,V>> reducer;
5470	>	if ((reducer = this.reducer) != null) {
5471	>	for (int i = baseIndex, f, h; batch > 0 &&
5472	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5473	>	addToPendingCount(1);
5474	>	(rights = new ReduceEntriesTask<K,V>
5475	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5476	>	rights, reducer)).fork();
5477	>	}
5478	>	Map.Entry<K,V> r = null;
5479	>	for (Node<K,V> p; (p = advance()) != null; )
5480	>	r = (r == null) ? p : reducer.apply(r, p);
5481	>	result = r;
5482	>	CountedCompleter<?> c;
5483	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5484	>	@SuppressWarnings("unchecked")
5485	>	ReduceEntriesTask<K,V>
5486	>	t = (ReduceEntriesTask<K,V>)c,
5487	>	s = t.rights;
5488	>	while (s != null) {
5489	>	Map.Entry<K,V> tr, sr;
5490	>	if ((sr = s.result) != null)
5491	>	t.result = (((tr = t.result) == null) ? sr :
5492	>	reducer.apply(tr, sr));
5493	>	s = t.rights = s.nextRight;
5494	>	}
5495	>	}
5496	>	}
5497		}
5498	+	}
5499
5500	<	public V getValue() {
5501	<	return value;
5500	>	@SuppressWarnings("serial")
5501	>	static final class MapReduceKeysTask<K,V,U>
5502	>	extends BulkTask<K,V,U> {
5503	>	final Function<? super K, ? extends U> transformer;
5504	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5505	>	U result;
5506	>	MapReduceKeysTask<K,V,U> rights, nextRight;
5507	>	MapReduceKeysTask
5508	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5509	>	MapReduceKeysTask<K,V,U> nextRight,
5510	>	Function<? super K, ? extends U> transformer,
5511	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5512	>	super(p, b, i, f, t); this.nextRight = nextRight;
5513	>	this.transformer = transformer;
5514	>	this.reducer = reducer;
5515	>	}
5516	>	public final U getRawResult() { return result; }
5517	>	public final void compute() {
5518	>	final Function<? super K, ? extends U> transformer;
5519	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5520	>	if ((transformer = this.transformer) != null &&
5521	>	(reducer = this.reducer) != null) {
5522	>	for (int i = baseIndex, f, h; batch > 0 &&
5523	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5524	>	addToPendingCount(1);
5525	>	(rights = new MapReduceKeysTask<K,V,U>
5526	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5527	>	rights, transformer, reducer)).fork();
5528	>	}
5529	>	U r = null;
5530	>	for (Node<K,V> p; (p = advance()) != null; ) {
5531	>	U u;
5532	>	if ((u = transformer.apply(p.key)) != null)
5533	>	r = (r == null) ? u : reducer.apply(r, u);
5534	>	}
5535	>	result = r;
5536	>	CountedCompleter<?> c;
5537	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5538	>	@SuppressWarnings("unchecked")
5539	>	MapReduceKeysTask<K,V,U>
5540	>	t = (MapReduceKeysTask<K,V,U>)c,
5541	>	s = t.rights;
5542	>	while (s != null) {
5543	>	U tr, sr;
5544	>	if ((sr = s.result) != null)
5545	>	t.result = (((tr = t.result) == null) ? sr :
5546	>	reducer.apply(tr, sr));
5547	>	s = t.rights = s.nextRight;
5548	>	}
5549	>	}
5550	>	}
5551		}
5552	+	}
5553
5554	<	public V setValue(V value) {
5555	<	V oldValue = this.value;
5556	<	this.value = value;
5557	<	return oldValue;
5554	>	@SuppressWarnings("serial")
5555	>	static final class MapReduceValuesTask<K,V,U>
5556	>	extends BulkTask<K,V,U> {
5557	>	final Function<? super V, ? extends U> transformer;
5558	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5559	>	U result;
5560	>	MapReduceValuesTask<K,V,U> rights, nextRight;
5561	>	MapReduceValuesTask
5562	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5563	>	MapReduceValuesTask<K,V,U> nextRight,
5564	>	Function<? super V, ? extends U> transformer,
5565	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5566	>	super(p, b, i, f, t); this.nextRight = nextRight;
5567	>	this.transformer = transformer;
5568	>	this.reducer = reducer;
5569	>	}
5570	>	public final U getRawResult() { return result; }
5571	>	public final void compute() {
5572	>	final Function<? super V, ? extends U> transformer;
5573	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5574	>	if ((transformer = this.transformer) != null &&
5575	>	(reducer = this.reducer) != null) {
5576	>	for (int i = baseIndex, f, h; batch > 0 &&
5577	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5578	>	addToPendingCount(1);
5579	>	(rights = new MapReduceValuesTask<K,V,U>
5580	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5581	>	rights, transformer, reducer)).fork();
5582	>	}
5583	>	U r = null;
5584	>	for (Node<K,V> p; (p = advance()) != null; ) {
5585	>	U u;
5586	>	if ((u = transformer.apply(p.val)) != null)
5587	>	r = (r == null) ? u : reducer.apply(r, u);
5588	>	}
5589	>	result = r;
5590	>	CountedCompleter<?> c;
5591	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5592	>	@SuppressWarnings("unchecked")
5593	>	MapReduceValuesTask<K,V,U>
5594	>	t = (MapReduceValuesTask<K,V,U>)c,
5595	>	s = t.rights;
5596	>	while (s != null) {
5597	>	U tr, sr;
5598	>	if ((sr = s.result) != null)
5599	>	t.result = (((tr = t.result) == null) ? sr :
5600	>	reducer.apply(tr, sr));
5601	>	s = t.rights = s.nextRight;
5602	>	}
5603	>	}
5604	>	}
5605		}
5606	+	}
5607
5608	<	public boolean equals(Object o) {
5609	<	if (!(o instanceof Map.Entry))
5610	<	return false;
5611	<	Map.Entry e = (Map.Entry)o;
5612	<	return eq(key, e.getKey()) && eq(value, e.getValue());
5608	>	@SuppressWarnings("serial")
5609	>	static final class MapReduceEntriesTask<K,V,U>
5610	>	extends BulkTask<K,V,U> {
5611	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5612	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5613	>	U result;
5614	>	MapReduceEntriesTask<K,V,U> rights, nextRight;
5615	>	MapReduceEntriesTask
5616	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5617	>	MapReduceEntriesTask<K,V,U> nextRight,
5618	>	Function<Map.Entry<K,V>, ? extends U> transformer,
5619	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5620	>	super(p, b, i, f, t); this.nextRight = nextRight;
5621	>	this.transformer = transformer;
5622	>	this.reducer = reducer;
5623	>	}
5624	>	public final U getRawResult() { return result; }
5625	>	public final void compute() {
5626	>	final Function<Map.Entry<K,V>, ? extends U> transformer;
5627	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5628	>	if ((transformer = this.transformer) != null &&
5629	>	(reducer = this.reducer) != null) {
5630	>	for (int i = baseIndex, f, h; batch > 0 &&
5631	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5632	>	addToPendingCount(1);
5633	>	(rights = new MapReduceEntriesTask<K,V,U>
5634	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5635	>	rights, transformer, reducer)).fork();
5636	>	}
5637	>	U r = null;
5638	>	for (Node<K,V> p; (p = advance()) != null; ) {
5639	>	U u;
5640	>	if ((u = transformer.apply(p)) != null)
5641	>	r = (r == null) ? u : reducer.apply(r, u);
5642	>	}
5643	>	result = r;
5644	>	CountedCompleter<?> c;
5645	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5646	>	@SuppressWarnings("unchecked")
5647	>	MapReduceEntriesTask<K,V,U>
5648	>	t = (MapReduceEntriesTask<K,V,U>)c,
5649	>	s = t.rights;
5650	>	while (s != null) {
5651	>	U tr, sr;
5652	>	if ((sr = s.result) != null)
5653	>	t.result = (((tr = t.result) == null) ? sr :
5654	>	reducer.apply(tr, sr));
5655	>	s = t.rights = s.nextRight;
5656	>	}
5657	>	}
5658	>	}
5659		}
5660	+	}
5661
5662	<	public int hashCode() {
5663	<	return ((key   == null)   ? 0 :   key.hashCode()) ^
5664	<	((value == null)   ? 0 : value.hashCode());
5662	>	@SuppressWarnings("serial")
5663	>	static final class MapReduceMappingsTask<K,V,U>
5664	>	extends BulkTask<K,V,U> {
5665	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5666	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5667	>	U result;
5668	>	MapReduceMappingsTask<K,V,U> rights, nextRight;
5669	>	MapReduceMappingsTask
5670	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5671	>	MapReduceMappingsTask<K,V,U> nextRight,
5672	>	BiFunction<? super K, ? super V, ? extends U> transformer,
5673	>	BiFunction<? super U, ? super U, ? extends U> reducer) {
5674	>	super(p, b, i, f, t); this.nextRight = nextRight;
5675	>	this.transformer = transformer;
5676	>	this.reducer = reducer;
5677	>	}
5678	>	public final U getRawResult() { return result; }
5679	>	public final void compute() {
5680	>	final BiFunction<? super K, ? super V, ? extends U> transformer;
5681	>	final BiFunction<? super U, ? super U, ? extends U> reducer;
5682	>	if ((transformer = this.transformer) != null &&
5683	>	(reducer = this.reducer) != null) {
5684	>	for (int i = baseIndex, f, h; batch > 0 &&
5685	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5686	>	addToPendingCount(1);
5687	>	(rights = new MapReduceMappingsTask<K,V,U>
5688	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5689	>	rights, transformer, reducer)).fork();
5690	>	}
5691	>	U r = null;
5692	>	for (Node<K,V> p; (p = advance()) != null; ) {
5693	>	U u;
5694	>	if ((u = transformer.apply(p.key, p.val)) != null)
5695	>	r = (r == null) ? u : reducer.apply(r, u);
5696	>	}
5697	>	result = r;
5698	>	CountedCompleter<?> c;
5699	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5700	>	@SuppressWarnings("unchecked")
5701	>	MapReduceMappingsTask<K,V,U>
5702	>	t = (MapReduceMappingsTask<K,V,U>)c,
5703	>	s = t.rights;
5704	>	while (s != null) {
5705	>	U tr, sr;
5706	>	if ((sr = s.result) != null)
5707	>	t.result = (((tr = t.result) == null) ? sr :
5708	>	reducer.apply(tr, sr));
5709	>	s = t.rights = s.nextRight;
5710	>	}
5711	>	}
5712	>	}
5713		}
5714	+	}
5715
5716	<	public String toString() {
5717	<	return key + "=" + value;
5716	>	@SuppressWarnings("serial")
5717	>	static final class MapReduceKeysToDoubleTask<K,V>
5718	>	extends BulkTask<K,V,Double> {
5719	>	final ToDoubleFunction<? super K> transformer;
5720	>	final DoubleBinaryOperator reducer;
5721	>	final double basis;
5722	>	double result;
5723	>	MapReduceKeysToDoubleTask<K,V> rights, nextRight;
5724	>	MapReduceKeysToDoubleTask
5725	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5726	>	MapReduceKeysToDoubleTask<K,V> nextRight,
5727	>	ToDoubleFunction<? super K> transformer,
5728	>	double basis,
5729	>	DoubleBinaryOperator reducer) {
5730	>	super(p, b, i, f, t); this.nextRight = nextRight;
5731	>	this.transformer = transformer;
5732	>	this.basis = basis; this.reducer = reducer;
5733	>	}
5734	>	public final Double getRawResult() { return result; }
5735	>	public final void compute() {
5736	>	final ToDoubleFunction<? super K> transformer;
5737	>	final DoubleBinaryOperator reducer;
5738	>	if ((transformer = this.transformer) != null &&
5739	>	(reducer = this.reducer) != null) {
5740	>	double r = this.basis;
5741	>	for (int i = baseIndex, f, h; batch > 0 &&
5742	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5743	>	addToPendingCount(1);
5744	>	(rights = new MapReduceKeysToDoubleTask<K,V>
5745	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5746	>	rights, transformer, r, reducer)).fork();
5747	>	}
5748	>	for (Node<K,V> p; (p = advance()) != null; )
5749	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key));
5750	>	result = r;
5751	>	CountedCompleter<?> c;
5752	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5753	>	@SuppressWarnings("unchecked")
5754	>	MapReduceKeysToDoubleTask<K,V>
5755	>	t = (MapReduceKeysToDoubleTask<K,V>)c,
5756	>	s = t.rights;
5757	>	while (s != null) {
5758	>	t.result = reducer.applyAsDouble(t.result, s.result);
5759	>	s = t.rights = s.nextRight;
5760	>	}
5761	>	}
5762	>	}
5763		}
5764	+	}
5765
5766	<	static boolean eq(Object o1, Object o2) {
5767	<	return (o1 == null ? o2 == null : o1.equals(o2));
5766	>	@SuppressWarnings("serial")
5767	>	static final class MapReduceValuesToDoubleTask<K,V>
5768	>	extends BulkTask<K,V,Double> {
5769	>	final ToDoubleFunction<? super V> transformer;
5770	>	final DoubleBinaryOperator reducer;
5771	>	final double basis;
5772	>	double result;
5773	>	MapReduceValuesToDoubleTask<K,V> rights, nextRight;
5774	>	MapReduceValuesToDoubleTask
5775	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5776	>	MapReduceValuesToDoubleTask<K,V> nextRight,
5777	>	ToDoubleFunction<? super V> transformer,
5778	>	double basis,
5779	>	DoubleBinaryOperator reducer) {
5780	>	super(p, b, i, f, t); this.nextRight = nextRight;
5781	>	this.transformer = transformer;
5782	>	this.basis = basis; this.reducer = reducer;
5783	>	}
5784	>	public final Double getRawResult() { return result; }
5785	>	public final void compute() {
5786	>	final ToDoubleFunction<? super V> transformer;
5787	>	final DoubleBinaryOperator reducer;
5788	>	if ((transformer = this.transformer) != null &&
5789	>	(reducer = this.reducer) != null) {
5790	>	double r = this.basis;
5791	>	for (int i = baseIndex, f, h; batch > 0 &&
5792	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5793	>	addToPendingCount(1);
5794	>	(rights = new MapReduceValuesToDoubleTask<K,V>
5795	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5796	>	rights, transformer, r, reducer)).fork();
5797	>	}
5798	>	for (Node<K,V> p; (p = advance()) != null; )
5799	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.val));
5800	>	result = r;
5801	>	CountedCompleter<?> c;
5802	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5803	>	@SuppressWarnings("unchecked")
5804	>	MapReduceValuesToDoubleTask<K,V>
5805	>	t = (MapReduceValuesToDoubleTask<K,V>)c,
5806	>	s = t.rights;
5807	>	while (s != null) {
5808	>	t.result = reducer.applyAsDouble(t.result, s.result);
5809	>	s = t.rights = s.nextRight;
5810	>	}
5811	>	}
5812	>	}
5813		}
5814		}
5815
5816	<	/* ---------------- Serialization Support -------------- */
5816	>	@SuppressWarnings("serial")
5817	>	static final class MapReduceEntriesToDoubleTask<K,V>
5818	>	extends BulkTask<K,V,Double> {
5819	>	final ToDoubleFunction<Map.Entry<K,V>> transformer;
5820	>	final DoubleBinaryOperator reducer;
5821	>	final double basis;
5822	>	double result;
5823	>	MapReduceEntriesToDoubleTask<K,V> rights, nextRight;
5824	>	MapReduceEntriesToDoubleTask
5825	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5826	>	MapReduceEntriesToDoubleTask<K,V> nextRight,
5827	>	ToDoubleFunction<Map.Entry<K,V>> transformer,
5828	>	double basis,
5829	>	DoubleBinaryOperator reducer) {
5830	>	super(p, b, i, f, t); this.nextRight = nextRight;
5831	>	this.transformer = transformer;
5832	>	this.basis = basis; this.reducer = reducer;
5833	>	}
5834	>	public final Double getRawResult() { return result; }
5835	>	public final void compute() {
5836	>	final ToDoubleFunction<Map.Entry<K,V>> transformer;
5837	>	final DoubleBinaryOperator reducer;
5838	>	if ((transformer = this.transformer) != null &&
5839	>	(reducer = this.reducer) != null) {
5840	>	double r = this.basis;
5841	>	for (int i = baseIndex, f, h; batch > 0 &&
5842	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5843	>	addToPendingCount(1);
5844	>	(rights = new MapReduceEntriesToDoubleTask<K,V>
5845	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5846	>	rights, transformer, r, reducer)).fork();
5847	>	}
5848	>	for (Node<K,V> p; (p = advance()) != null; )
5849	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p));
5850	>	result = r;
5851	>	CountedCompleter<?> c;
5852	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5853	>	@SuppressWarnings("unchecked")
5854	>	MapReduceEntriesToDoubleTask<K,V>
5855	>	t = (MapReduceEntriesToDoubleTask<K,V>)c,
5856	>	s = t.rights;
5857	>	while (s != null) {
5858	>	t.result = reducer.applyAsDouble(t.result, s.result);
5859	>	s = t.rights = s.nextRight;
5860	>	}
5861	>	}
5862	>	}
5863	>	}
5864	>	}
5865
5866	<	/**
5867	<	* Save the state of the <tt>ConcurrentHashMap</tt>
5868	<	* instance to a stream (i.e.,
5869	<	* serialize it).
5870	<	* @param s the stream
5871	<	* @serialData
5872	<	* the key (Object) and value (Object)
5873	<	* for each key-value mapping, followed by a null pair.
5874	<	* The key-value mappings are emitted in no particular order.
5875	<	*/
5876	<	private void writeObject(java.io.ObjectOutputStream s) throws IOException  {
5877	<	s.defaultWriteObject();
5866	>	@SuppressWarnings("serial")
5867	>	static final class MapReduceMappingsToDoubleTask<K,V>
5868	>	extends BulkTask<K,V,Double> {
5869	>	final ToDoubleBiFunction<? super K, ? super V> transformer;
5870	>	final DoubleBinaryOperator reducer;
5871	>	final double basis;
5872	>	double result;
5873	>	MapReduceMappingsToDoubleTask<K,V> rights, nextRight;
5874	>	MapReduceMappingsToDoubleTask
5875	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5876	>	MapReduceMappingsToDoubleTask<K,V> nextRight,
5877	>	ToDoubleBiFunction<? super K, ? super V> transformer,
5878	>	double basis,
5879	>	DoubleBinaryOperator reducer) {
5880	>	super(p, b, i, f, t); this.nextRight = nextRight;
5881	>	this.transformer = transformer;
5882	>	this.basis = basis; this.reducer = reducer;
5883	>	}
5884	>	public final Double getRawResult() { return result; }
5885	>	public final void compute() {
5886	>	final ToDoubleBiFunction<? super K, ? super V> transformer;
5887	>	final DoubleBinaryOperator reducer;
5888	>	if ((transformer = this.transformer) != null &&
5889	>	(reducer = this.reducer) != null) {
5890	>	double r = this.basis;
5891	>	for (int i = baseIndex, f, h; batch > 0 &&
5892	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5893	>	addToPendingCount(1);
5894	>	(rights = new MapReduceMappingsToDoubleTask<K,V>
5895	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5896	>	rights, transformer, r, reducer)).fork();
5897	>	}
5898	>	for (Node<K,V> p; (p = advance()) != null; )
5899	>	r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key, p.val));
5900	>	result = r;
5901	>	CountedCompleter<?> c;
5902	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5903	>	@SuppressWarnings("unchecked")
5904	>	MapReduceMappingsToDoubleTask<K,V>
5905	>	t = (MapReduceMappingsToDoubleTask<K,V>)c,
5906	>	s = t.rights;
5907	>	while (s != null) {
5908	>	t.result = reducer.applyAsDouble(t.result, s.result);
5909	>	s = t.rights = s.nextRight;
5910	>	}
5911	>	}
5912	>	}
5913	>	}
5914	>	}
5915
5916	<	for (int k = 0; k < segments.length; ++k) {
5917	<	Segment<K,V> seg = (Segment<K,V>)segments[k];
5918	<	seg.lock();
5919	<	try {
5920	<	HashEntry[] tab = seg.table;
5921	<	for (int i = 0; i < tab.length; ++i) {
5922	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i]; e != null; e = e.next) {
5923	<	s.writeObject(e.key);
5924	<	s.writeObject(e.value);
5916	>	@SuppressWarnings("serial")
5917	>	static final class MapReduceKeysToLongTask<K,V>
5918	>	extends BulkTask<K,V,Long> {
5919	>	final ToLongFunction<? super K> transformer;
5920	>	final LongBinaryOperator reducer;
5921	>	final long basis;
5922	>	long result;
5923	>	MapReduceKeysToLongTask<K,V> rights, nextRight;
5924	>	MapReduceKeysToLongTask
5925	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5926	>	MapReduceKeysToLongTask<K,V> nextRight,
5927	>	ToLongFunction<? super K> transformer,
5928	>	long basis,
5929	>	LongBinaryOperator reducer) {
5930	>	super(p, b, i, f, t); this.nextRight = nextRight;
5931	>	this.transformer = transformer;
5932	>	this.basis = basis; this.reducer = reducer;
5933	>	}
5934	>	public final Long getRawResult() { return result; }
5935	>	public final void compute() {
5936	>	final ToLongFunction<? super K> transformer;
5937	>	final LongBinaryOperator reducer;
5938	>	if ((transformer = this.transformer) != null &&
5939	>	(reducer = this.reducer) != null) {
5940	>	long r = this.basis;
5941	>	for (int i = baseIndex, f, h; batch > 0 &&
5942	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5943	>	addToPendingCount(1);
5944	>	(rights = new MapReduceKeysToLongTask<K,V>
5945	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5946	>	rights, transformer, r, reducer)).fork();
5947	>	}
5948	>	for (Node<K,V> p; (p = advance()) != null; )
5949	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.key));
5950	>	result = r;
5951	>	CountedCompleter<?> c;
5952	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
5953	>	@SuppressWarnings("unchecked")
5954	>	MapReduceKeysToLongTask<K,V>
5955	>	t = (MapReduceKeysToLongTask<K,V>)c,
5956	>	s = t.rights;
5957	>	while (s != null) {
5958	>	t.result = reducer.applyAsLong(t.result, s.result);
5959	>	s = t.rights = s.nextRight;
5960		}
5961		}
1384	–	} finally {
1385	–	seg.unlock();
5962		}
5963		}
1388	–	s.writeObject(null);
1389	–	s.writeObject(null);
5964		}
5965
5966	<	/**
5967	<	* Reconstitute the <tt>ConcurrentHashMap</tt>
5968	<	* instance from a stream (i.e.,
5969	<	* deserialize it).
5970	<	* @param s the stream
5971	<	*/
5972	<	private void readObject(java.io.ObjectInputStream s)
5973	<	throws IOException, ClassNotFoundException  {
5974	<	s.defaultReadObject();
5966	>	@SuppressWarnings("serial")
5967	>	static final class MapReduceValuesToLongTask<K,V>
5968	>	extends BulkTask<K,V,Long> {
5969	>	final ToLongFunction<? super V> transformer;
5970	>	final LongBinaryOperator reducer;
5971	>	final long basis;
5972	>	long result;
5973	>	MapReduceValuesToLongTask<K,V> rights, nextRight;
5974	>	MapReduceValuesToLongTask
5975	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
5976	>	MapReduceValuesToLongTask<K,V> nextRight,
5977	>	ToLongFunction<? super V> transformer,
5978	>	long basis,
5979	>	LongBinaryOperator reducer) {
5980	>	super(p, b, i, f, t); this.nextRight = nextRight;
5981	>	this.transformer = transformer;
5982	>	this.basis = basis; this.reducer = reducer;
5983	>	}
5984	>	public final Long getRawResult() { return result; }
5985	>	public final void compute() {
5986	>	final ToLongFunction<? super V> transformer;
5987	>	final LongBinaryOperator reducer;
5988	>	if ((transformer = this.transformer) != null &&
5989	>	(reducer = this.reducer) != null) {
5990	>	long r = this.basis;
5991	>	for (int i = baseIndex, f, h; batch > 0 &&
5992	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
5993	>	addToPendingCount(1);
5994	>	(rights = new MapReduceValuesToLongTask<K,V>
5995	>	(this, batch >>>= 1, baseLimit = h, f, tab,
5996	>	rights, transformer, r, reducer)).fork();
5997	>	}
5998	>	for (Node<K,V> p; (p = advance()) != null; )
5999	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.val));
6000	>	result = r;
6001	>	CountedCompleter<?> c;
6002	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6003	>	@SuppressWarnings("unchecked")
6004	>	MapReduceValuesToLongTask<K,V>
6005	>	t = (MapReduceValuesToLongTask<K,V>)c,
6006	>	s = t.rights;
6007	>	while (s != null) {
6008	>	t.result = reducer.applyAsLong(t.result, s.result);
6009	>	s = t.rights = s.nextRight;
6010	>	}
6011	>	}
6012	>	}
6013	>	}
6014	>	}
6015
6016	<	// Initialize each segment to be minimally sized, and let grow.
6017	<	for (int i = 0; i < segments.length; ++i) {
6018	<	segments[i].setTable(new HashEntry[1]);
6016	>	@SuppressWarnings("serial")
6017	>	static final class MapReduceEntriesToLongTask<K,V>
6018	>	extends BulkTask<K,V,Long> {
6019	>	final ToLongFunction<Map.Entry<K,V>> transformer;
6020	>	final LongBinaryOperator reducer;
6021	>	final long basis;
6022	>	long result;
6023	>	MapReduceEntriesToLongTask<K,V> rights, nextRight;
6024	>	MapReduceEntriesToLongTask
6025	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6026	>	MapReduceEntriesToLongTask<K,V> nextRight,
6027	>	ToLongFunction<Map.Entry<K,V>> transformer,
6028	>	long basis,
6029	>	LongBinaryOperator reducer) {
6030	>	super(p, b, i, f, t); this.nextRight = nextRight;
6031	>	this.transformer = transformer;
6032	>	this.basis = basis; this.reducer = reducer;
6033	>	}
6034	>	public final Long getRawResult() { return result; }
6035	>	public final void compute() {
6036	>	final ToLongFunction<Map.Entry<K,V>> transformer;
6037	>	final LongBinaryOperator reducer;
6038	>	if ((transformer = this.transformer) != null &&
6039	>	(reducer = this.reducer) != null) {
6040	>	long r = this.basis;
6041	>	for (int i = baseIndex, f, h; batch > 0 &&
6042	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6043	>	addToPendingCount(1);
6044	>	(rights = new MapReduceEntriesToLongTask<K,V>
6045	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6046	>	rights, transformer, r, reducer)).fork();
6047	>	}
6048	>	for (Node<K,V> p; (p = advance()) != null; )
6049	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p));
6050	>	result = r;
6051	>	CountedCompleter<?> c;
6052	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6053	>	@SuppressWarnings("unchecked")
6054	>	MapReduceEntriesToLongTask<K,V>
6055	>	t = (MapReduceEntriesToLongTask<K,V>)c,
6056	>	s = t.rights;
6057	>	while (s != null) {
6058	>	t.result = reducer.applyAsLong(t.result, s.result);
6059	>	s = t.rights = s.nextRight;
6060	>	}
6061	>	}
6062	>	}
6063		}
6064	+	}
6065
6066	<	// Read the keys and values, and put the mappings in the table
6067	<	for (;;) {
6068	<	K key = (K) s.readObject();
6069	<	V value = (V) s.readObject();
6070	<	if (key == null)
6071	<	break;
6072	<	put(key, value);
6066	>	@SuppressWarnings("serial")
6067	>	static final class MapReduceMappingsToLongTask<K,V>
6068	>	extends BulkTask<K,V,Long> {
6069	>	final ToLongBiFunction<? super K, ? super V> transformer;
6070	>	final LongBinaryOperator reducer;
6071	>	final long basis;
6072	>	long result;
6073	>	MapReduceMappingsToLongTask<K,V> rights, nextRight;
6074	>	MapReduceMappingsToLongTask
6075	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6076	>	MapReduceMappingsToLongTask<K,V> nextRight,
6077	>	ToLongBiFunction<? super K, ? super V> transformer,
6078	>	long basis,
6079	>	LongBinaryOperator reducer) {
6080	>	super(p, b, i, f, t); this.nextRight = nextRight;
6081	>	this.transformer = transformer;
6082	>	this.basis = basis; this.reducer = reducer;
6083	>	}
6084	>	public final Long getRawResult() { return result; }
6085	>	public final void compute() {
6086	>	final ToLongBiFunction<? super K, ? super V> transformer;
6087	>	final LongBinaryOperator reducer;
6088	>	if ((transformer = this.transformer) != null &&
6089	>	(reducer = this.reducer) != null) {
6090	>	long r = this.basis;
6091	>	for (int i = baseIndex, f, h; batch > 0 &&
6092	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6093	>	addToPendingCount(1);
6094	>	(rights = new MapReduceMappingsToLongTask<K,V>
6095	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6096	>	rights, transformer, r, reducer)).fork();
6097	>	}
6098	>	for (Node<K,V> p; (p = advance()) != null; )
6099	>	r = reducer.applyAsLong(r, transformer.applyAsLong(p.key, p.val));
6100	>	result = r;
6101	>	CountedCompleter<?> c;
6102	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6103	>	@SuppressWarnings("unchecked")
6104	>	MapReduceMappingsToLongTask<K,V>
6105	>	t = (MapReduceMappingsToLongTask<K,V>)c,
6106	>	s = t.rights;
6107	>	while (s != null) {
6108	>	t.result = reducer.applyAsLong(t.result, s.result);
6109	>	s = t.rights = s.nextRight;
6110	>	}
6111	>	}
6112	>	}
6113	>	}
6114	>	}
6115	>
6116	>	@SuppressWarnings("serial")
6117	>	static final class MapReduceKeysToIntTask<K,V>
6118	>	extends BulkTask<K,V,Integer> {
6119	>	final ToIntFunction<? super K> transformer;
6120	>	final IntBinaryOperator reducer;
6121	>	final int basis;
6122	>	int result;
6123	>	MapReduceKeysToIntTask<K,V> rights, nextRight;
6124	>	MapReduceKeysToIntTask
6125	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6126	>	MapReduceKeysToIntTask<K,V> nextRight,
6127	>	ToIntFunction<? super K> transformer,
6128	>	int basis,
6129	>	IntBinaryOperator reducer) {
6130	>	super(p, b, i, f, t); this.nextRight = nextRight;
6131	>	this.transformer = transformer;
6132	>	this.basis = basis; this.reducer = reducer;
6133	>	}
6134	>	public final Integer getRawResult() { return result; }
6135	>	public final void compute() {
6136	>	final ToIntFunction<? super K> transformer;
6137	>	final IntBinaryOperator reducer;
6138	>	if ((transformer = this.transformer) != null &&
6139	>	(reducer = this.reducer) != null) {
6140	>	int r = this.basis;
6141	>	for (int i = baseIndex, f, h; batch > 0 &&
6142	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6143	>	addToPendingCount(1);
6144	>	(rights = new MapReduceKeysToIntTask<K,V>
6145	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6146	>	rights, transformer, r, reducer)).fork();
6147	>	}
6148	>	for (Node<K,V> p; (p = advance()) != null; )
6149	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.key));
6150	>	result = r;
6151	>	CountedCompleter<?> c;
6152	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6153	>	@SuppressWarnings("unchecked")
6154	>	MapReduceKeysToIntTask<K,V>
6155	>	t = (MapReduceKeysToIntTask<K,V>)c,
6156	>	s = t.rights;
6157	>	while (s != null) {
6158	>	t.result = reducer.applyAsInt(t.result, s.result);
6159	>	s = t.rights = s.nextRight;
6160	>	}
6161	>	}
6162	>	}
6163	>	}
6164	>	}
6165	>
6166	>	@SuppressWarnings("serial")
6167	>	static final class MapReduceValuesToIntTask<K,V>
6168	>	extends BulkTask<K,V,Integer> {
6169	>	final ToIntFunction<? super V> transformer;
6170	>	final IntBinaryOperator reducer;
6171	>	final int basis;
6172	>	int result;
6173	>	MapReduceValuesToIntTask<K,V> rights, nextRight;
6174	>	MapReduceValuesToIntTask
6175	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6176	>	MapReduceValuesToIntTask<K,V> nextRight,
6177	>	ToIntFunction<? super V> transformer,
6178	>	int basis,
6179	>	IntBinaryOperator reducer) {
6180	>	super(p, b, i, f, t); this.nextRight = nextRight;
6181	>	this.transformer = transformer;
6182	>	this.basis = basis; this.reducer = reducer;
6183	>	}
6184	>	public final Integer getRawResult() { return result; }
6185	>	public final void compute() {
6186	>	final ToIntFunction<? super V> transformer;
6187	>	final IntBinaryOperator reducer;
6188	>	if ((transformer = this.transformer) != null &&
6189	>	(reducer = this.reducer) != null) {
6190	>	int r = this.basis;
6191	>	for (int i = baseIndex, f, h; batch > 0 &&
6192	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6193	>	addToPendingCount(1);
6194	>	(rights = new MapReduceValuesToIntTask<K,V>
6195	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6196	>	rights, transformer, r, reducer)).fork();
6197	>	}
6198	>	for (Node<K,V> p; (p = advance()) != null; )
6199	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p.val));
6200	>	result = r;
6201	>	CountedCompleter<?> c;
6202	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6203	>	@SuppressWarnings("unchecked")
6204	>	MapReduceValuesToIntTask<K,V>
6205	>	t = (MapReduceValuesToIntTask<K,V>)c,
6206	>	s = t.rights;
6207	>	while (s != null) {
6208	>	t.result = reducer.applyAsInt(t.result, s.result);
6209	>	s = t.rights = s.nextRight;
6210	>	}
6211	>	}
6212	>	}
6213	>	}
6214	>	}
6215	>
6216	>	@SuppressWarnings("serial")
6217	>	static final class MapReduceEntriesToIntTask<K,V>
6218	>	extends BulkTask<K,V,Integer> {
6219	>	final ToIntFunction<Map.Entry<K,V>> transformer;
6220	>	final IntBinaryOperator reducer;
6221	>	final int basis;
6222	>	int result;
6223	>	MapReduceEntriesToIntTask<K,V> rights, nextRight;
6224	>	MapReduceEntriesToIntTask
6225	>	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6226	>	MapReduceEntriesToIntTask<K,V> nextRight,
6227	>	ToIntFunction<Map.Entry<K,V>> transformer,
6228	>	int basis,
6229	>	IntBinaryOperator reducer) {
6230	>	super(p, b, i, f, t); this.nextRight = nextRight;
6231	>	this.transformer = transformer;
6232	>	this.basis = basis; this.reducer = reducer;
6233	>	}
6234	>	public final Integer getRawResult() { return result; }
6235	>	public final void compute() {
6236	>	final ToIntFunction<Map.Entry<K,V>> transformer;
6237	>	final IntBinaryOperator reducer;
6238	>	if ((transformer = this.transformer) != null &&
6239	>	(reducer = this.reducer) != null) {
6240	>	int r = this.basis;
6241	>	for (int i = baseIndex, f, h; batch > 0 &&
6242	>	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6243	>	addToPendingCount(1);
6244	>	(rights = new MapReduceEntriesToIntTask<K,V>
6245	>	(this, batch >>>= 1, baseLimit = h, f, tab,
6246	>	rights, transformer, r, reducer)).fork();
6247	>	}
6248	>	for (Node<K,V> p; (p = advance()) != null; )
6249	>	r = reducer.applyAsInt(r, transformer.applyAsInt(p));
6250	>	result = r;
6251	>	CountedCompleter<?> c;
6252	>	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6253	>	@SuppressWarnings("unchecked")
6254	>	MapReduceEntriesToIntTask<K,V>
6255	>	t = (MapReduceEntriesToIntTask<K,V>)c,
6256	>	s = t.rights;
6257	>	while (s != null) {
6258	>	t.result = reducer.applyAsInt(t.result, s.result);
6259	>	s = t.rights = s.nextRight;
6260	>	}
6261	>	}
6262	>	}
6263		}
6264		}
1416	–	}
6265
6266	+	@SuppressWarnings("serial")
6267	+	static final class MapReduceMappingsToIntTask<K,V>
6268	+	extends BulkTask<K,V,Integer> {
6269	+	final ToIntBiFunction<? super K, ? super V> transformer;
6270	+	final IntBinaryOperator reducer;
6271	+	final int basis;
6272	+	int result;
6273	+	MapReduceMappingsToIntTask<K,V> rights, nextRight;
6274	+	MapReduceMappingsToIntTask
6275	+	(BulkTask<K,V,?> p, int b, int i, int f, Node<K,V>[] t,
6276	+	MapReduceMappingsToIntTask<K,V> nextRight,
6277	+	ToIntBiFunction<? super K, ? super V> transformer,
6278	+	int basis,
6279	+	IntBinaryOperator reducer) {
6280	+	super(p, b, i, f, t); this.nextRight = nextRight;
6281	+	this.transformer = transformer;
6282	+	this.basis = basis; this.reducer = reducer;
6283	+	}
6284	+	public final Integer getRawResult() { return result; }
6285	+	public final void compute() {
6286	+	final ToIntBiFunction<? super K, ? super V> transformer;
6287	+	final IntBinaryOperator reducer;
6288	+	if ((transformer = this.transformer) != null &&
6289	+	(reducer = this.reducer) != null) {
6290	+	int r = this.basis;
6291	+	for (int i = baseIndex, f, h; batch > 0 &&
6292	+	(h = ((f = baseLimit) + i) >>> 1) > i;) {
6293	+	addToPendingCount(1);
6294	+	(rights = new MapReduceMappingsToIntTask<K,V>
6295	+	(this, batch >>>= 1, baseLimit = h, f, tab,
6296	+	rights, transformer, r, reducer)).fork();
6297	+	}
6298	+	for (Node<K,V> p; (p = advance()) != null; )
6299	+	r = reducer.applyAsInt(r, transformer.applyAsInt(p.key, p.val));
6300	+	result = r;
6301	+	CountedCompleter<?> c;
6302	+	for (c = firstComplete(); c != null; c = c.nextComplete()) {
6303	+	@SuppressWarnings("unchecked")
6304	+	MapReduceMappingsToIntTask<K,V>
6305	+	t = (MapReduceMappingsToIntTask<K,V>)c,
6306	+	s = t.rights;
6307	+	while (s != null) {
6308	+	t.result = reducer.applyAsInt(t.result, s.result);
6309	+	s = t.rights = s.nextRight;
6310	+	}
6311	+	}
6312	+	}
6313	+	}
6314	+	}
6315	+
6316	+	// Unsafe mechanics
6317	+	private static final Unsafe U = Unsafe.getUnsafe();
6318	+	private static final long SIZECTL
6319	+	= U.objectFieldOffset(ConcurrentHashMap.class, "sizeCtl");
6320	+	private static final long TRANSFERINDEX
6321	+	= U.objectFieldOffset(ConcurrentHashMap.class, "transferIndex");
6322	+	private static final long BASECOUNT
6323	+	= U.objectFieldOffset(ConcurrentHashMap.class, "baseCount");
6324	+	private static final long CELLSBUSY
6325	+	= U.objectFieldOffset(ConcurrentHashMap.class, "cellsBusy");
6326	+	private static final long CELLVALUE
6327	+	= U.objectFieldOffset(CounterCell.class, "value");
6328	+	private static final int ABASE = U.arrayBaseOffset(Node[].class);
6329	+	private static final int ASHIFT;
6330	+
6331	+	static {
6332	+	int scale = U.arrayIndexScale(Node[].class);
6333	+	if ((scale & (scale - 1)) != 0)
6334	+	throw new ExceptionInInitializerError("array index scale not a power of two");
6335	+	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6336	+
6337	+	// Reduce the risk of rare disastrous classloading in first call to
6338	+	// LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773
6339	+	Class<?> ensureLoaded = LockSupport.class;
6340	+
6341	+	// Eager class load observed to help JIT during startup
6342	+	ensureLoaded = ReservationNode.class;
6343	+	}
6344	+	}

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