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Comparing jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java (file contents):
Revision 1.24 by dl, Fri Oct 10 23:51:28 2003 UTC vs.
Revision 1.66 by jsr166, Mon May 2 21:51:38 2005 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3	<	* Expert Group and released to the public domain. Use, modify, and
4	<	* redistribute this code in any way without acknowledgement.
3	>	* Expert Group and released to the public domain, as explained at
4	>	* http://creativecommons.org/licenses/publicdomain
5		*/
6
7		package java.util.concurrent;
#	Line 17 | Line 17 | import java.io.ObjectOutputStream;
17		* adjustable expected concurrency for updates. This class obeys the
18		* same functional specification as {@link java.util.Hashtable}, and
19		* includes versions of methods corresponding to each method of
20	<	* <tt>Hashtable</tt> . However, even though all operations are
20	>	* <tt>Hashtable</tt>. However, even though all operations are
21		* thread-safe, retrieval operations do <em>not</em> entail locking,
22		* and there is <em>not</em> any support for locking the entire table
23		* in a way that prevents all access.  This class is fully
24		* interoperable with <tt>Hashtable</tt> in programs that rely on its
25		* thread safety but not on its synchronization details.
26		*
27	<	* <p> Retrieval operations (including <tt>get</tt>) ordinarily
28	<	* overlap with update operations (including <tt>put</tt> and
29	<	* <tt>remove</tt>). Retrievals reflect the results of the most
30	<	* recently <em>completed</em> update operations holding upon their
31	<	* onset.  For aggregate operations such as <tt>putAll</tt> and
32	<	* <tt>clear</tt>, concurrent retrievals may reflect insertion or
27	>	* <p> Retrieval operations (including <tt>get</tt>) generally do not
28	>	* block, so may overlap with update operations (including
29	>	* <tt>put</tt> and <tt>remove</tt>). Retrievals reflect the results
30	>	* of the most recently <em>completed</em> update operations holding
31	>	* upon their onset.  For aggregate operations such as <tt>putAll</tt>
32	>	* and <tt>clear</tt>, concurrent retrievals may reflect insertion or
33		* removal of only some entries.  Similarly, Iterators and
34		* Enumerations return elements reflecting the state of the hash table
35		* at some point at or since the creation of the iterator/enumeration.
36	<	* They do <em>not</em> throw <tt>ConcurrentModificationException</tt>.
37	<	* However, Iterators are designed to be used by only one thread at a
38	<	* time.
36	>	* They do <em>not</em> throw
37	>	* {@link ConcurrentModificationException}.  However, iterators are
38	>	* designed to be used by only one thread at a time.
39		*
40		* <p> The allowed concurrency among update operations is guided by
41		* the optional <tt>concurrencyLevel</tt> constructor argument
42	<	* (default 16), which is used as a hint for internal sizing.  The
42	>	* (default <tt>16</tt>), which is used as a hint for internal sizing.  The
43		* table is internally partitioned to try to permit the indicated
44		* number of concurrent updates without contention. Because placement
45		* in hash tables is essentially random, the actual concurrency will
46		* vary.  Ideally, you should choose a value to accommodate as many
47	<	* threads as will ever concurrently access the table. Using a
47	>	* threads as will ever concurrently modify the table. Using a
48		* significantly higher value than you need can waste space and time,
49		* and a significantly lower value can lead to thread contention. But
50		* overestimates and underestimates within an order of magnitude do
51	<	* not usually have much noticeable impact.
51	>	* not usually have much noticeable impact. A value of one is
52	>	* appropriate when it is known that only one thread will modify and
53	>	* all others will only read. Also, resizing this or any other kind of
54	>	* hash table is a relatively slow operation, so, when possible, it is
55	>	* a good idea to provide estimates of expected table sizes in
56	>	* constructors.
57		*
58	<	* <p>This class implements all of the <em>optional</em> methods
59	<	* of the {@link Map} and {@link Iterator} interfaces.
58	>	* <p>This class and its views and iterators implement all of the
59	>	* <em>optional</em> methods of the {@link Map} and {@link Iterator}
60	>	* interfaces.
61		*
62		* <p> Like {@link java.util.Hashtable} but unlike {@link
63		* java.util.HashMap}, this class does NOT allow <tt>null</tt> to be
64		* used as a key or value.
65		*
66	+	* <p>This class is a member of the
67	+	* <a href="{@docRoot}/../guide/collections/index.html">
68	+	* Java Collections Framework</a>.
69	+	*
70		* @since 1.5
71		* @author Doug Lea
72	+	* @param <K> the type of keys maintained by this map
73	+	* @param <V> the type of mapped values
74		*/
75		public class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
76	<	implements ConcurrentMap<K, V>, Cloneable, Serializable {
76	>	implements ConcurrentMap<K, V>, Serializable {
77		private static final long serialVersionUID = 7249069246763182397L;
78
79		/*
#	Line 72 | Line 84 | public class ConcurrentHashMap<K, V> ext
84		/* ---------------- Constants -------------- */
85
86		/**
87	<	* The default initial number of table slots for this table.
88	<	* Used when not otherwise specified in constructor.
87	>	* The default initial capacity for this table,
88	>	* used when not otherwise specified in a constructor.
89	>	*/
90	>	static final int DEFAULT_INITIAL_CAPACITY = 16;
91	>
92	>	/**
93	>	* The default load factor for this table, used when not
94	>	* otherwise specified in a constructor.
95	>	*/
96	>	static final float DEFAULT_LOAD_FACTOR = 0.75f;
97	>
98	>	/**
99	>	* The default concurrency level for this table, used when not
100	>	* otherwise specified in a constructor.
101		*/
102	<	private static int DEFAULT_INITIAL_CAPACITY = 16;
102	>	static final int DEFAULT_CONCURRENCY_LEVEL = 16;
103
104		/**
105		* The maximum capacity, used if a higher value is implicitly
#	Line 83 | Line 107 | public class ConcurrentHashMap<K, V> ext
107		* be a power of two <= 1<<30 to ensure that entries are indexible
108		* using ints.
109		*/
110	<	static final int MAXIMUM_CAPACITY = 1 << 30;
110	>	static final int MAXIMUM_CAPACITY = 1 << 30;
111
112		/**
113	<	* The default load factor for this table.  Used when not
114	<	* otherwise specified in constructor.
113	>	* The maximum number of segments to allow; used to bound
114	>	* constructor arguments.
115		*/
116	<	static final float DEFAULT_LOAD_FACTOR = 0.75f;
93	<
94	<	/**
95	<	* The default number of concurrency control segments.
96	<	**/
97	<	private static final int DEFAULT_SEGMENTS = 16;
116	>	static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
117
118		/**
119	<	* The maximum number of segments to allow; used to bound ctor arguments.
119	>	* Number of unsynchronized retries in size and containsValue
120	>	* methods before resorting to locking. This is used to avoid
121	>	* unbounded retries if tables undergo continuous modification
122	>	* which would make it impossible to obtain an accurate result.
123		*/
124	<	private static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
124	>	static final int RETRIES_BEFORE_LOCK = 2;
125
126		/* ---------------- Fields -------------- */
127
128		/**
129		* Mask value for indexing into segments. The upper bits of a
130		* key's hash code are used to choose the segment.
131	<	**/
132	<	private final int segmentMask;
131	>	*/
132	>	final int segmentMask;
133
134		/**
135		* Shift value for indexing within segments.
136	<	**/
137	<	private final int segmentShift;
136	>	*/
137	>	final int segmentShift;
138
139		/**
140		* The segments, each of which is a specialized hash table
141		*/
142	<	private final Segment[] segments;
142	>	final Segment[] segments;
143
144	<	private transient Set<K> keySet;
145	<	private transient Set<Map.Entry<K,V>> entrySet;
146	<	private transient Collection<V> values;
144	>	transient Set<K> keySet;
145	>	transient Set<Map.Entry<K,V>> entrySet;
146	>	transient Collection<V> values;
147
148		/* ---------------- Small Utilities -------------- */
149
150		/**
151	<	* Return a hash code for non-null Object x.
152	<	* Uses the same hash code spreader as most other j.u hash tables.
151	>	* Returns a hash code for non-null Object x.
152	>	* Uses the same hash code spreader as most other java.util hash tables.
153		* @param x the object serving as a key
154		* @return the hash code
155		*/
156	<	private static int hash(Object x) {
156	>	static int hash(Object x) {
157		int h = x.hashCode();
158		h += ~(h << 9);
159		h ^=  (h >>> 14);
#	Line 141 | Line 163 | public class ConcurrentHashMap<K, V> ext
163		}
164
165		/**
166	<	* Return the segment that should be used for key with given hash
166	>	* Returns the segment that should be used for key with given hash
167	>	* @param hash the hash code for the key
168	>	* @return the segment
169		*/
170	<	private Segment<K,V> segmentFor(int hash) {
170	>	final Segment<K,V> segmentFor(int hash) {
171		return (Segment<K,V>) segments[(hash >>> segmentShift) & segmentMask];
172		}
173
174		/* ---------------- Inner Classes -------------- */
175
176		/**
177	+	* ConcurrentHashMap list entry. Note that this is never exported
178	+	* out as a user-visible Map.Entry.
179	+	*
180	+	* Because the value field is volatile, not final, it is legal wrt
181	+	* the Java Memory Model for an unsynchronized reader to see null
182	+	* instead of initial value when read via a data race.  Although a
183	+	* reordering leading to this is not likely to ever actually
184	+	* occur, the Segment.readValueUnderLock method is used as a
185	+	* backup in case a null (pre-initialized) value is ever seen in
186	+	* an unsynchronized access method.
187	+	*/
188	+	static final class HashEntry<K,V> {
189	+	final K key;
190	+	final int hash;
191	+	volatile V value;
192	+	final HashEntry<K,V> next;
193	+
194	+	HashEntry(K key, int hash, HashEntry<K,V> next, V value) {
195	+	this.key = key;
196	+	this.hash = hash;
197	+	this.next = next;
198	+	this.value = value;
199	+	}
200	+	}
201	+
202	+	/**
203		* Segments are specialized versions of hash tables.  This
204		* subclasses from ReentrantLock opportunistically, just to
205		* simplify some locking and avoid separate construction.
206	<	**/
207	<	private static final class Segment<K,V> extends ReentrantLock implements Serializable {
206	>	*/
207	>	static final class Segment<K,V> extends ReentrantLock implements Serializable {
208		/*
209		* Segments maintain a table of entry lists that are ALWAYS
210		* kept in a consistent state, so can be read without locking.
#	Line 167 | Line 217 | public class ConcurrentHashMap<K, V> ext
217		* is less than two for the default load factor threshold.)
218		*
219		* Read operations can thus proceed without locking, but rely
220	<	* on a memory barrier to ensure that completed write
221	<	* operations performed by other threads are
222	<	* noticed. Conveniently, the "count" field, tracking the
223	<	* number of elements, can also serve as the volatile variable
224	<	* providing proper read/write barriers. This is convenient
225	<	* because this field needs to be read in many read operations
176	<	* anyway.
220	>	* on selected uses of volatiles to ensure that completed
221	>	* write operations performed by other threads are
222	>	* noticed. For most purposes, the "count" field, tracking the
223	>	* number of elements, serves as that volatile variable
224	>	* ensuring visibility.  This is convenient because this field
225	>	* needs to be read in many read operations anyway:
226		*
227	<	* Implementors note. The basic rules for all this are:
179	<	*
180	<	*   - All unsynchronized read operations must first read the
227	>	*   - All (unsynchronized) read operations must first read the
228		*     "count" field, and should not look at table entries if
229		*     it is 0.
230		*
231	<	*   - All synchronized write operations should write to
232	<	*     the "count" field after updating. The operations must not
233	<	*     take any action that could even momentarily cause
234	<	*     a concurrent read operation to see inconsistent
235	<	*     data. This is made easier by the nature of the read
236	<	*     operations in Map. For example, no operation
231	>	*   - All (synchronized) write operations should write to
232	>	*     the "count" field after structurally changing any bin.
233	>	*     The operations must not take any action that could even
234	>	*     momentarily cause a concurrent read operation to see
235	>	*     inconsistent data. This is made easier by the nature of
236	>	*     the read operations in Map. For example, no operation
237		*     can reveal that the table has grown but the threshold
238		*     has not yet been updated, so there are no atomicity
239		*     requirements for this with respect to reads.
240		*
241	<	* As a guide, all critical volatile reads and writes are marked
242	<	* in code comments.
241	>	* As a guide, all critical volatile reads and writes to the
242	>	* count field are marked in code comments.
243		*/
244
245		private static final long serialVersionUID = 2249069246763182397L;
246
247		/**
248		* The number of elements in this segment's region.
249	<	**/
249	>	*/
250		transient volatile int count;
251
252		/**
253	<	* Number of updates; used for checking lack of modifications
254	<	* in bulk-read methods.
253	>	* Number of updates that alter the size of the table. This is
254	>	* used during bulk-read methods to make sure they see a
255	>	* consistent snapshot: If modCounts change during a traversal
256	>	* of segments computing size or checking containsValue, then
257	>	* we might have an inconsistent view of state so (usually)
258	>	* must retry.
259		*/
260		transient int modCount;
261
#	Line 213 | Line 264 | public class ConcurrentHashMap<K, V> ext
264		* (The value of this field is always (int)(capacity *
265		* loadFactor).)
266		*/
267	<	private transient int threshold;
267	>	transient int threshold;
268
269		/**
270	<	* The per-segment table
270	>	* The per-segment table. Declared as a raw type, casted
271	>	* to HashEntry<K,V> on each use.
272		*/
273	<	transient HashEntry[] table;
273	>	transient volatile HashEntry[] table;
274
275		/**
276		* The load factor for the hash table.  Even though this value
#	Line 226 | Line 278 | public class ConcurrentHashMap<K, V> ext
278		* links to outer object.
279		* @serial
280		*/
281	<	private final float loadFactor;
281	>	final float loadFactor;
282
283		Segment(int initialCapacity, float lf) {
284		loadFactor = lf;
#	Line 234 | Line 286 | public class ConcurrentHashMap<K, V> ext
286		}
287
288		/**
289	<	* Set table to new HashEntry array.
289	>	* Sets table to new HashEntry array.
290		* Call only while holding lock or in constructor.
291	<	**/
292	<	private void setTable(HashEntry[] newTable) {
241	<	table = newTable;
291	>	*/
292	>	void setTable(HashEntry[] newTable) {
293		threshold = (int)(newTable.length * loadFactor);
294	<	count = count; // write-volatile
294	>	table = newTable;
295	>	}
296	>
297	>	/**
298	>	* Returns properly casted first entry of bin for given hash.
299	>	*/
300	>	HashEntry<K,V> getFirst(int hash) {
301	>	HashEntry[] tab = table;
302	>	return (HashEntry<K,V>) tab[hash & (tab.length - 1)];
303	>	}
304	>
305	>	/**
306	>	* Reads value field of an entry under lock. Called if value
307	>	* field ever appears to be null. This is possible only if a
308	>	* compiler happens to reorder a HashEntry initialization with
309	>	* its table assignment, which is legal under memory model
310	>	* but is not known to ever occur.
311	>	*/
312	>	V readValueUnderLock(HashEntry<K,V> e) {
313	>	lock();
314	>	try {
315	>	return e.value;
316	>	} finally {
317	>	unlock();
318	>	}
319		}
320
321		/* Specialized implementations of map methods */
322
323	<	V get(K key, int hash) {
323	>	V get(Object key, int hash) {
324		if (count != 0) { // read-volatile
325	<	HashEntry[] tab = table;
251	<	int index = hash & (tab.length - 1);
252	<	HashEntry<K,V> e = (HashEntry<K,V>) tab[index];
325	>	HashEntry<K,V> e = getFirst(hash);
326		while (e != null) {
327	<	if (e.hash == hash && key.equals(e.key))
328	<	return e.value;
327	>	if (e.hash == hash && key.equals(e.key)) {
328	>	V v = e.value;
329	>	if (v != null)
330	>	return v;
331	>	return readValueUnderLock(e); // recheck
332	>	}
333		e = e.next;
334		}
335		}
#	Line 261 | Line 338 | public class ConcurrentHashMap<K, V> ext
338
339		boolean containsKey(Object key, int hash) {
340		if (count != 0) { // read-volatile
341	<	HashEntry[] tab = table;
265	<	int index = hash & (tab.length - 1);
266	<	HashEntry<K,V> e = (HashEntry<K,V>) tab[index];
341	>	HashEntry<K,V> e = getFirst(hash);
342		while (e != null) {
343		if (e.hash == hash && key.equals(e.key))
344		return true;
#	Line 277 | Line 352 | public class ConcurrentHashMap<K, V> ext
352		if (count != 0) { // read-volatile
353		HashEntry[] tab = table;
354		int len = tab.length;
355	<	for (int i = 0 ; i < len; i++)
356	<	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i] ; e != null ; e = e.next)
357	<	if (value.equals(e.value))
355	>	for (int i = 0 ; i < len; i++) {
356	>	for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i];
357	>	e != null ;
358	>	e = e.next) {
359	>	V v = e.value;
360	>	if (v == null) // recheck
361	>	v = readValueUnderLock(e);
362	>	if (value.equals(v))
363		return true;
364	+	}
365	+	}
366		}
367		return false;
368		}
369
370	+	boolean replace(K key, int hash, V oldValue, V newValue) {
371	+	lock();
372	+	try {
373	+	HashEntry<K,V> e = getFirst(hash);
374	+	while (e != null && (e.hash != hash || !key.equals(e.key)))
375	+	e = e.next;
376	+
377	+	boolean replaced = false;
378	+	if (e != null && oldValue.equals(e.value)) {
379	+	replaced = true;
380	+	e.value = newValue;
381	+	}
382	+	return replaced;
383	+	} finally {
384	+	unlock();
385	+	}
386	+	}
387	+
388	+	V replace(K key, int hash, V newValue) {
389	+	lock();
390	+	try {
391	+	HashEntry<K,V> e = getFirst(hash);
392	+	while (e != null && (e.hash != hash || !key.equals(e.key)))
393	+	e = e.next;
394	+
395	+	V oldValue = null;
396	+	if (e != null) {
397	+	oldValue = e.value;
398	+	e.value = newValue;
399	+	}
400	+	return oldValue;
401	+	} finally {
402	+	unlock();
403	+	}
404	+	}
405	+
406	+
407		V put(K key, int hash, V value, boolean onlyIfAbsent) {
408		lock();
409		try {
410		int c = count;
411	+	if (c++ > threshold) // ensure capacity
412	+	rehash();
413		HashEntry[] tab = table;
414		int index = hash & (tab.length - 1);
415		HashEntry<K,V> first = (HashEntry<K,V>) tab[index];
416	+	HashEntry<K,V> e = first;
417	+	while (e != null && (e.hash != hash || !key.equals(e.key)))
418	+	e = e.next;
419
420	<	for (HashEntry<K,V> e = first; e != null; e = (HashEntry<K,V>) e.next) {
421	<	if (e.hash == hash && key.equals(e.key)) {
422	<	V oldValue = e.value;
423	<	if (!onlyIfAbsent)
424	<	e.value = value;
301	<	++modCount;
302	<	count = c; // write-volatile
303	<	return oldValue;
304	<	}
420	>	V oldValue;
421	>	if (e != null) {
422	>	oldValue = e.value;
423	>	if (!onlyIfAbsent)
424	>	e.value = value;
425		}
426	<
427	<	tab[index] = new HashEntry<K,V>(hash, key, value, first);
428	<	++modCount;
429	<	++c;
430	<	count = c; // write-volatile
431	<	if (c > threshold)
432	<	setTable(rehash(tab));
313	<	return null;
426	>	else {
427	>	oldValue = null;
428	>	++modCount;
429	>	tab[index] = new HashEntry<K,V>(key, hash, first, value);
430	>	count = c; // write-volatile
431	>	}
432	>	return oldValue;
433		} finally {
434		unlock();
435		}
436		}
437
438	<	private HashEntry[] rehash(HashEntry[] oldTable) {
438	>	void rehash() {
439	>	HashEntry[] oldTable = table;
440		int oldCapacity = oldTable.length;
441		if (oldCapacity >= MAXIMUM_CAPACITY)
442	<	return oldTable;
442	>	return;
443
444		/*
445		* Reclassify nodes in each list to new Map.  Because we are
#	Line 328 | Line 448 | public class ConcurrentHashMap<K, V> ext
448		* offset. We eliminate unnecessary node creation by catching
449		* cases where old nodes can be reused because their next
450		* fields won't change. Statistically, at the default
451	<	* threshhold, only about one-sixth of them need cloning when
451	>	* threshold, only about one-sixth of them need cloning when
452		* a table doubles. The nodes they replace will be garbage
453		* collectable as soon as they are no longer referenced by any
454		* reader thread that may be in the midst of traversing table
#	Line 336 | Line 456 | public class ConcurrentHashMap<K, V> ext
456		*/
457
458		HashEntry[] newTable = new HashEntry[oldCapacity << 1];
459	+	threshold = (int)(newTable.length * loadFactor);
460		int sizeMask = newTable.length - 1;
461		for (int i = 0; i < oldCapacity ; i++) {
462		// We need to guarantee that any existing reads of old Map can
#	Line 368 | Line 489 | public class ConcurrentHashMap<K, V> ext
489		// Clone all remaining nodes
490		for (HashEntry<K,V> p = e; p != lastRun; p = p.next) {
491		int k = p.hash & sizeMask;
492	<	newTable[k] = new HashEntry<K,V>(p.hash,
493	<	p.key,
494	<	p.value,
374	<	(HashEntry<K,V>) newTable[k]);
492	>	HashEntry<K,V> n = (HashEntry<K,V>)newTable[k];
493	>	newTable[k] = new HashEntry<K,V>(p.key, p.hash,
494	>	n, p.value);
495		}
496		}
497		}
498		}
499	<	return newTable;
499	>	table = newTable;
500		}
501
502		/**
#	Line 385 | Line 505 | public class ConcurrentHashMap<K, V> ext
505		V remove(Object key, int hash, Object value) {
506		lock();
507		try {
508	<	int c = count;
508	>	int c = count - 1;
509		HashEntry[] tab = table;
510		int index = hash & (tab.length - 1);
511		HashEntry<K,V> first = (HashEntry<K,V>)tab[index];
392	–
512		HashEntry<K,V> e = first;
513	<	for (;;) {
395	<	if (e == null)
396	<	return null;
397	<	if (e.hash == hash && key.equals(e.key))
398	<	break;
513	>	while (e != null && (e.hash != hash || !key.equals(e.key)))
514		e = e.next;
400	–	}
515
516	<	V oldValue = e.value;
517	<	if (value != null && !value.equals(oldValue))
518	<	return null;
519	<
520	<	// All entries following removed node can stay in list, but
521	<	// all preceeding ones need to be cloned.
522	<	HashEntry<K,V> newFirst = e.next;
523	<	for (HashEntry<K,V> p = first; p != e; p = p.next)
524	<	newFirst = new HashEntry<K,V>(p.hash, p.key,
525	<	p.value, newFirst);
526	<	tab[index] = newFirst;
527	<	++modCount;
528	<	count = c-1; // write-volatile
516	>	V oldValue = null;
517	>	if (e != null) {
518	>	V v = e.value;
519	>	if (value == null || value.equals(v)) {
520	>	oldValue = v;
521	>	// All entries following removed node can stay
522	>	// in list, but all preceding ones need to be
523	>	// cloned.
524	>	++modCount;
525	>	HashEntry<K,V> newFirst = e.next;
526	>	for (HashEntry<K,V> p = first; p != e; p = p.next)
527	>	newFirst = new HashEntry<K,V>(p.key, p.hash,
528	>	newFirst, p.value);
529	>	tab[index] = newFirst;
530	>	count = c; // write-volatile
531	>	}
532	>	}
533		return oldValue;
534		} finally {
535		unlock();
#	Line 419 | Line 537 | public class ConcurrentHashMap<K, V> ext
537		}
538
539		void clear() {
540	<	lock();
541	<	try {
542	<	HashEntry[] tab = table;
543	<	for (int i = 0; i < tab.length ; i++)
544	<	tab[i] = null;
545	<	++modCount;
546	<	count = 0; // write-volatile
547	<	} finally {
548	<	unlock();
540	>	if (count != 0) {
541	>	lock();
542	>	try {
543	>	HashEntry[] tab = table;
544	>	for (int i = 0; i < tab.length ; i++)
545	>	tab[i] = null;
546	>	++modCount;
547	>	count = 0; // write-volatile
548	>	} finally {
549	>	unlock();
550	>	}
551		}
552		}
553		}
554
435	–	/**
436	–	* ConcurrentHashMap list entry.
437	–	*/
438	–	private static class HashEntry<K,V> implements Entry<K,V> {
439	–	private final K key;
440	–	private V value;
441	–	private final int hash;
442	–	private final HashEntry<K,V> next;
443	–
444	–	HashEntry(int hash, K key, V value, HashEntry<K,V> next) {
445	–	this.value = value;
446	–	this.hash = hash;
447	–	this.key = key;
448	–	this.next = next;
449	–	}
450	–
451	–	public K getKey() {
452	–	return key;
453	–	}
454	–
455	–	public V getValue() {
456	–	return value;
457	–	}
458	–
459	–	public V setValue(V newValue) {
460	–	// We aren't required to, and don't provide any
461	–	// visibility barriers for setting value.
462	–	if (newValue == null)
463	–	throw new NullPointerException();
464	–	V oldValue = this.value;
465	–	this.value = newValue;
466	–	return oldValue;
467	–	}
468	–
469	–	public boolean equals(Object o) {
470	–	if (!(o instanceof Entry))
471	–	return false;
472	–	Entry<K,V> e = (Entry<K,V>)o;
473	–	return (key.equals(e.getKey()) && value.equals(e.getValue()));
474	–	}
475	–
476	–	public int hashCode() {
477	–	return  key.hashCode() ^ value.hashCode();
478	–	}
479	–
480	–	public String toString() {
481	–	return key + "=" + value;
482	–	}
483	–	}
555
556
557		/* ---------------- Public operations -------------- */
558
559		/**
560	<	* Constructs a new, empty map with the specified initial
561	<	* capacity and the specified load factor.
560	>	* Creates a new, empty map with the specified initial
561	>	* capacity, load factor and concurrency level.
562		*
563		* @param initialCapacity the initial capacity. The implementation
564		* performs internal sizing to accommodate this many elements.
565		* @param loadFactor  the load factor threshold, used to control resizing.
566	+	* Resizing may be performed when the average number of elements per
567	+	* bin exceeds this threshold.
568		* @param concurrencyLevel the estimated number of concurrently
569		* updating threads. The implementation performs internal sizing
570	<	* to try to accommodate this many threads.
570	>	* to try to accommodate this many threads.
571		* @throws IllegalArgumentException if the initial capacity is
572		* negative or the load factor or concurrencyLevel are
573		* nonpositive.
#	Line 532 | Line 605 | public class ConcurrentHashMap<K, V> ext
605		}
606
607		/**
608	<	* Constructs a new, empty map with the specified initial
609	<	* capacity,  and with default load factor and concurrencyLevel.
608	>	* Creates a new, empty map with the specified initial capacity
609	>	* and load factor and with the default concurrencyLevel
610	>	* (<tt>16</tt>).
611		*
612		* @param initialCapacity The implementation performs internal
613		* sizing to accommodate this many elements.
614	+	* @param loadFactor  the load factor threshold, used to control resizing.
615	+	* @throws IllegalArgumentException if the initial capacity of
616	+	* elements is negative or the load factor is nonpositive
617	+	*/
618	+	public ConcurrentHashMap(int initialCapacity, float loadFactor) {
619	+	this(initialCapacity, loadFactor, DEFAULT_CONCURRENCY_LEVEL);
620	+	}
621	+
622	+	/**
623	+	* Creates a new, empty map with the specified initial capacity,
624	+	* and with default load factor (<tt>0.75f</tt>)
625	+	* and concurrencyLevel (<tt>16</tt>).
626	+	*
627	+	* @param initialCapacity the initial capacity. The implementation
628	+	* performs internal sizing to accommodate this many elements.
629		* @throws IllegalArgumentException if the initial capacity of
630		* elements is negative.
631		*/
632		public ConcurrentHashMap(int initialCapacity) {
633	<	this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
633	>	this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
634		}
635
636		/**
637	<	* Constructs a new, empty map with a default initial capacity,
638	<	* load factor, and concurrencyLevel.
637	>	* Creates a new, empty map with a default initial capacity
638	>	* (<tt>16</tt>), load factor
639	>	* (<tt>0.75f</tt>), and concurrencyLevel
640	>	* (<tt>16</tt>).
641		*/
642		public ConcurrentHashMap() {
643	<	this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
643	>	this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
644		}
645
646		/**
647	<	* Constructs a new map with the same mappings as the given map.  The
648	<	* map is created with a capacity of twice the number of mappings in
649	<	* the given map or 11 (whichever is greater), and a default load factor.
647	>	* Creates a new map with the same mappings as the given map.  The
648	>	* map is created with a capacity of 1.5 times the number of
649	>	* mappings in the given map or <tt>16</tt>
650	>	* (whichever is greater), and a default load factor
651	>	* (<tt>0.75f</tt>) and concurrencyLevel
652	>	* (<tt>16</tt>).
653	>	* @param t the map
654		*/
655	<	public <A extends K, B extends V> ConcurrentHashMap(Map<A,B> t) {
655	>	public ConcurrentHashMap(Map<? extends K, ? extends V> t) {
656		this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1,
657	<	11),
658	<	DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS);
657	>	DEFAULT_INITIAL_CAPACITY),
658	>	DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
659		putAll(t);
660		}
661
662	<	// inherit Map javadoc
662	>	/**
663	>	* Returns <tt>true</tt> if this map contains no key-value mappings.
664	>	*
665	>	* @return <tt>true</tt> if this map contains no key-value mappings.
666	>	*/
667		public boolean isEmpty() {
668	+	final Segment[] segments = this.segments;
669		/*
670	<	* We need to keep track of per-segment modCounts to avoid ABA
670	>	* We keep track of per-segment modCounts to avoid ABA
671		* problems in which an element in one segment was added and
672		* in another removed during traversal, in which case the
673		* table was never actually empty at any point. Note the
#	Line 580 | Line 680 | public class ConcurrentHashMap<K, V> ext
680		for (int i = 0; i < segments.length; ++i) {
681		if (segments[i].count != 0)
682		return false;
683	<	else
683	>	else
684		mcsum += mc[i] = segments[i].modCount;
685		}
686		// If mcsum happens to be zero, then we know we got a snapshot
#	Line 589 | Line 689 | public class ConcurrentHashMap<K, V> ext
689		if (mcsum != 0) {
690		for (int i = 0; i < segments.length; ++i) {
691		if (segments[i].count != 0 ||
692	<	mc[i] != segments[i].modCount)
692	>	mc[i] != segments[i].modCount)
693		return false;
694		}
695		}
696		return true;
697		}
698
699	<	// inherit Map javadoc
699	>	/**
700	>	* Returns the number of key-value mappings in this map.  If the
701	>	* map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
702	>	* <tt>Integer.MAX_VALUE</tt>.
703	>	*
704	>	* @return the number of key-value mappings in this map.
705	>	*/
706		public int size() {
707	+	final Segment[] segments = this.segments;
708	+	long sum = 0;
709	+	long check = 0;
710		int[] mc = new int[segments.length];
711	<	for (;;) {
712	<	long sum = 0;
711	>	// Try a few times to get accurate count. On failure due to
712	>	// continuous async changes in table, resort to locking.
713	>	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
714	>	check = 0;
715	>	sum = 0;
716		int mcsum = 0;
717		for (int i = 0; i < segments.length; ++i) {
718		sum += segments[i].count;
719		mcsum += mc[i] = segments[i].modCount;
720		}
609	–	int check = 0;
721		if (mcsum != 0) {
722		for (int i = 0; i < segments.length; ++i) {
723		check += segments[i].count;
#	Line 616 | Line 727 | public class ConcurrentHashMap<K, V> ext
727		}
728		}
729		}
730	<	if (check == sum) {
731	<	if (sum > Integer.MAX_VALUE)
732	<	return Integer.MAX_VALUE;
733	<	else
734	<	return (int)sum;
735	<	}
730	>	if (check == sum)
731	>	break;
732	>	}
733	>	if (check != sum) { // Resort to locking all segments
734	>	sum = 0;
735	>	for (int i = 0; i < segments.length; ++i)
736	>	segments[i].lock();
737	>	for (int i = 0; i < segments.length; ++i)
738	>	sum += segments[i].count;
739	>	for (int i = 0; i < segments.length; ++i)
740	>	segments[i].unlock();
741		}
742	+	if (sum > Integer.MAX_VALUE)
743	+	return Integer.MAX_VALUE;
744	+	else
745	+	return (int)sum;
746		}
747
748
#	Line 638 | Line 758 | public class ConcurrentHashMap<K, V> ext
758		*/
759		public V get(Object key) {
760		int hash = hash(key); // throws NullPointerException if key null
761	<	return segmentFor(hash).get((K) key, hash);
761	>	return segmentFor(hash).get(key, hash);
762		}
763
764		/**
#	Line 671 | Line 791 | public class ConcurrentHashMap<K, V> ext
791		if (value == null)
792		throw new NullPointerException();
793
794	+	// See explanation of modCount use above
795	+
796	+	final Segment[] segments = this.segments;
797		int[] mc = new int[segments.length];
798	<	for (;;) {
798	>
799	>	// Try a few times without locking
800	>	for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
801		int sum = 0;
802		int mcsum = 0;
803		for (int i = 0; i < segments.length; ++i) {
#	Line 694 | Line 819 | public class ConcurrentHashMap<K, V> ext
819		if (cleanSweep)
820		return false;
821		}
822	+	// Resort to locking all segments
823	+	for (int i = 0; i < segments.length; ++i)
824	+	segments[i].lock();
825	+	boolean found = false;
826	+	try {
827	+	for (int i = 0; i < segments.length; ++i) {
828	+	if (segments[i].containsValue(value)) {
829	+	found = true;
830	+	break;
831	+	}
832	+	}
833	+	} finally {
834	+	for (int i = 0; i < segments.length; ++i)
835	+	segments[i].unlock();
836	+	}
837	+	return found;
838		}
839
840		/**
#	Line 718 | Line 859 | public class ConcurrentHashMap<K, V> ext
859		/**
860		* Maps the specified <tt>key</tt> to the specified
861		* <tt>value</tt> in this table. Neither the key nor the
862	<	* value can be <tt>null</tt>. <p>
862	>	* value can be <tt>null</tt>.
863		*
864	<	* The value can be retrieved by calling the <tt>get</tt> method
864	>	* <p> The value can be retrieved by calling the <tt>get</tt> method
865		* with a key that is equal to the original key.
866		*
867		* @param      key     the table key.
#	Line 742 | Line 883 | public class ConcurrentHashMap<K, V> ext
883		* with a value, associate it with the given value.
884		* This is equivalent to
885		* <pre>
886	<	*   if (!map.containsKey(key))
886	>	*   if (!map.containsKey(key))
887		*      return map.put(key, value);
888		*   else
889	<	*      return map.get(key);
890	<	* </pre>
750	<	* Except that the action is performed atomically.
889	>	*      return map.get(key);</pre>
890	>	* except that the action is performed atomically.
891		* @param key key with which the specified value is to be associated.
892		* @param value value to be associated with the specified key.
893		* @return previous value associated with specified key, or <tt>null</tt>
894	<	*         if there was no mapping for key.  A <tt>null</tt> return can
755	<	*         also indicate that the map previously associated <tt>null</tt>
756	<	*         with the specified key, if the implementation supports
757	<	*         <tt>null</tt> values.
758	<	*
759	<	* @throws UnsupportedOperationException if the <tt>put</tt> operation is
760	<	*            not supported by this map.
761	<	* @throws ClassCastException if the class of the specified key or value
762	<	*            prevents it from being stored in this map.
894	>	*         if there was no mapping for key.
895		* @throws NullPointerException if the specified key or value is
896		*            <tt>null</tt>.
897	<	*
766	<	**/
897	>	*/
898		public V putIfAbsent(K key, V value) {
899		if (value == null)
900		throw new NullPointerException();
#	Line 781 | Line 912 | public class ConcurrentHashMap<K, V> ext
912		* @param t Mappings to be stored in this map.
913		*/
914		public void putAll(Map<? extends K, ? extends V> t) {
915	<	for (Iterator<Map.Entry<? extends K, ? extends V>> it = (Iterator<Map.Entry<? extends K, ? extends V>>) t.entrySet().iterator(); it.hasNext(); ) {
915	>	for (Iterator<? extends Map.Entry<? extends K, ? extends V>> it = (Iterator<? extends Map.Entry<? extends K, ? extends V>>) t.entrySet().iterator(); it.hasNext(); ) {
916		Entry<? extends K, ? extends V> e = it.next();
917		put(e.getKey(), e.getValue());
918		}
#	Line 804 | Line 935 | public class ConcurrentHashMap<K, V> ext
935
936		/**
937		* Remove entry for key only if currently mapped to given value.
938	<	* Acts as
939	<	* <pre>
938	>	* This is equivalent to
939	>	* <pre>
940		*  if (map.get(key).equals(value)) {
941		*     map.remove(key);
942		*     return true;
943	<	* } else return false;
813	<	* </pre>
943	>	* } else return false;</pre>
944		* except that the action is performed atomically.
945		* @param key key with which the specified value is associated.
946		* @param value value associated with the specified key.
#	Line 823 | Line 953 | public class ConcurrentHashMap<K, V> ext
953		return segmentFor(hash).remove(key, hash, value) != null;
954		}
955
956	+
957		/**
958	<	* Removes all mappings from this map.
958	>	* Replaces entry for key only if currently mapped to given value.
959	>	* This is equivalent to
960	>	* <pre>
961	>	*  if (map.get(key).equals(oldValue)) {
962	>	*     map.put(key, newValue);
963	>	*     return true;
964	>	* } else return false;</pre>
965	>	* except that the action is performed atomically.
966	>	* @param key key with which the specified value is associated.
967	>	* @param oldValue value expected to be associated with the specified key.
968	>	* @param newValue value to be associated with the specified key.
969	>	* @return true if the value was replaced
970	>	* @throws NullPointerException if the specified key or values are
971	>	* <tt>null</tt>.
972		*/
973	<	public void clear() {
974	<	for (int i = 0; i < segments.length; ++i)
975	<	segments[i].clear();
973	>	public boolean replace(K key, V oldValue, V newValue) {
974	>	if (oldValue == null || newValue == null)
975	>	throw new NullPointerException();
976	>	int hash = hash(key);
977	>	return segmentFor(hash).replace(key, hash, oldValue, newValue);
978	>	}
979	>
980	>	/**
981	>	* Replaces entry for key only if currently mapped to some value.
982	>	* This is equivalent to
983	>	* <pre>
984	>	*  if (map.containsKey(key)) {
985	>	*     return map.put(key, value);
986	>	* } else return null;</pre>
987	>	* except that the action is performed atomically.
988	>	* @param key key with which the specified value is associated.
989	>	* @param value value to be associated with the specified key.
990	>	* @return previous value associated with specified key, or <tt>null</tt>
991	>	*         if there was no mapping for key.
992	>	* @throws NullPointerException if the specified key or value is
993	>	*            <tt>null</tt>.
994	>	*/
995	>	public V replace(K key, V value) {
996	>	if (value == null)
997	>	throw new NullPointerException();
998	>	int hash = hash(key);
999	>	return segmentFor(hash).replace(key, hash, value);
1000		}
1001
1002
1003		/**
1004	<	* Returns a shallow copy of this
837	<	* <tt>ConcurrentHashMap</tt> instance: the keys and
838	<	* values themselves are not cloned.
839	<	*
840	<	* @return a shallow copy of this map.
1004	>	* Removes all mappings from this map.
1005		*/
1006	<	public Object clone() {
1007	<	// We cannot call super.clone, since it would share final
1008	<	// segments array, and there's no way to reassign finals.
845	<
846	<	float lf = segments[0].loadFactor;
847	<	int segs = segments.length;
848	<	int cap = (int)(size() / lf);
849	<	if (cap < segs) cap = segs;
850	<	ConcurrentHashMap<K,V> t = new ConcurrentHashMap<K,V>(cap, lf, segs);
851	<	t.putAll(this);
852	<	return t;
1006	>	public void clear() {
1007	>	for (int i = 0; i < segments.length; ++i)
1008	>	segments[i].clear();
1009		}
1010
1011		/**
#	Line 860 | Line 1016 | public class ConcurrentHashMap<K, V> ext
1016		* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and
1017		* <tt>clear</tt> operations.  It does not support the <tt>add</tt> or
1018		* <tt>addAll</tt> operations.
1019	<	* The returned <tt>iterator</tt> is a "weakly consistent" iterator that
1019	>	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
1020		* will never throw {@link java.util.ConcurrentModificationException},
1021		* and guarantees to traverse elements as they existed upon
1022		* construction of the iterator, and may (but is not guaranteed to)
#	Line 882 | Line 1038 | public class ConcurrentHashMap<K, V> ext
1038		* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
1039		* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
1040		* It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
1041	<	* The returned <tt>iterator</tt> is a "weakly consistent" iterator that
1041	>	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
1042		* will never throw {@link java.util.ConcurrentModificationException},
1043		* and guarantees to traverse elements as they existed upon
1044		* construction of the iterator, and may (but is not guaranteed to)
#	Line 905 | Line 1061 | public class ConcurrentHashMap<K, V> ext
1061		* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
1062		* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
1063		* It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
1064	<	* The returned <tt>iterator</tt> is a "weakly consistent" iterator that
1064	>	* The view's returned <tt>iterator</tt> is a "weakly consistent" iterator that
1065		* will never throw {@link java.util.ConcurrentModificationException},
1066		* and guarantees to traverse elements as they existed upon
1067		* construction of the iterator, and may (but is not guaranteed to)
#	Line 915 | Line 1071 | public class ConcurrentHashMap<K, V> ext
1071		*/
1072		public Set<Map.Entry<K,V>> entrySet() {
1073		Set<Map.Entry<K,V>> es = entrySet;
1074	<	return (es != null) ? es : (entrySet = (Set<Map.Entry<K,V>>) (Set) new EntrySet());
1074	>	return (es != null) ? es : (entrySet = new EntrySet());
1075		}
1076
1077
#	Line 931 | Line 1087 | public class ConcurrentHashMap<K, V> ext
1087
1088		/**
1089		* Returns an enumeration of the values in this table.
934	–	* Use the Enumeration methods on the returned object to fetch the elements
935	–	* sequentially.
1090		*
1091		* @return  an enumeration of the values in this table.
1092		* @see     #values
#	Line 943 | Line 1097 | public class ConcurrentHashMap<K, V> ext
1097
1098		/* ---------------- Iterator Support -------------- */
1099
1100	<	private abstract class HashIterator {
1101	<	private int nextSegmentIndex;
1102	<	private int nextTableIndex;
1103	<	private HashEntry[] currentTable;
1104	<	private HashEntry<K, V> nextEntry;
1105	<	private HashEntry<K, V> lastReturned;
1100	>	abstract class HashIterator {
1101	>	int nextSegmentIndex;
1102	>	int nextTableIndex;
1103	>	HashEntry[] currentTable;
1104	>	HashEntry<K, V> nextEntry;
1105	>	HashEntry<K, V> lastReturned;
1106
1107	<	private HashIterator() {
1107	>	HashIterator() {
1108		nextSegmentIndex = segments.length - 1;
1109		nextTableIndex = -1;
1110		advance();
#	Line 958 | Line 1112 | public class ConcurrentHashMap<K, V> ext
1112
1113		public boolean hasMoreElements() { return hasNext(); }
1114
1115	<	private void advance() {
1115	>	final void advance() {
1116		if (nextEntry != null && (nextEntry = nextEntry.next) != null)
1117		return;
1118
#	Line 999 | Line 1153 | public class ConcurrentHashMap<K, V> ext
1153		}
1154		}
1155
1156	<	private class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> {
1156	>	final class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> {
1157		public K next() { return super.nextEntry().key; }
1158		public K nextElement() { return super.nextEntry().key; }
1159		}
1160
1161	<	private class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> {
1161	>	final class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> {
1162		public V next() { return super.nextEntry().value; }
1163		public V nextElement() { return super.nextEntry().value; }
1164		}
1165
1166	<	private class EntryIterator extends HashIterator implements Iterator<Entry<K,V>> {
1167	<	public Map.Entry<K,V> next() { return super.nextEntry(); }
1166	>
1167	>
1168	>	/**
1169	>	* Entry iterator. Exported Entry objects must write-through
1170	>	* changes in setValue, even if the nodes have been cloned. So we
1171	>	* cannot return internal HashEntry objects. Instead, the iterator
1172	>	* itself acts as a forwarding pseudo-entry.
1173	>	*/
1174	>	final class EntryIterator extends HashIterator implements Map.Entry<K,V>, Iterator<Entry<K,V>> {
1175	>	public Map.Entry<K,V> next() {
1176	>	nextEntry();
1177	>	return this;
1178	>	}
1179	>
1180	>	public K getKey() {
1181	>	if (lastReturned == null)
1182	>	throw new IllegalStateException("Entry was removed");
1183	>	return lastReturned.key;
1184	>	}
1185	>
1186	>	public V getValue() {
1187	>	if (lastReturned == null)
1188	>	throw new IllegalStateException("Entry was removed");
1189	>	return ConcurrentHashMap.this.get(lastReturned.key);
1190	>	}
1191	>
1192	>	public V setValue(V value) {
1193	>	if (lastReturned == null)
1194	>	throw new IllegalStateException("Entry was removed");
1195	>	return ConcurrentHashMap.this.put(lastReturned.key, value);
1196	>	}
1197	>
1198	>	public boolean equals(Object o) {
1199	>	// If not acting as entry, just use default.
1200	>	if (lastReturned == null)
1201	>	return super.equals(o);
1202	>	if (!(o instanceof Map.Entry))
1203	>	return false;
1204	>	Map.Entry e = (Map.Entry)o;
1205	>	return eq(getKey(), e.getKey()) && eq(getValue(), e.getValue());
1206	>	}
1207	>
1208	>	public int hashCode() {
1209	>	// If not acting as entry, just use default.
1210	>	if (lastReturned == null)
1211	>	return super.hashCode();
1212	>
1213	>	Object k = getKey();
1214	>	Object v = getValue();
1215	>	return ((k == null) ? 0 : k.hashCode()) ^
1216	>	((v == null) ? 0 : v.hashCode());
1217	>	}
1218	>
1219	>	public String toString() {
1220	>	// If not acting as entry, just use default.
1221	>	if (lastReturned == null)
1222	>	return super.toString();
1223	>	else
1224	>	return getKey() + "=" + getValue();
1225	>	}
1226	>
1227	>	boolean eq(Object o1, Object o2) {
1228	>	return (o1 == null ? o2 == null : o1.equals(o2));
1229	>	}
1230	>
1231		}
1232
1233	<	private class KeySet extends AbstractSet<K> {
1233	>	final class KeySet extends AbstractSet<K> {
1234		public Iterator<K> iterator() {
1235		return new KeyIterator();
1236		}
#	Line 1029 | Line 1246 | public class ConcurrentHashMap<K, V> ext
1246		public void clear() {
1247		ConcurrentHashMap.this.clear();
1248		}
1249	+	public Object[] toArray() {
1250	+	Collection<K> c = new ArrayList<K>();
1251	+	for (Iterator<K> i = iterator(); i.hasNext(); )
1252	+	c.add(i.next());
1253	+	return c.toArray();
1254	+	}
1255	+	public <T> T[] toArray(T[] a) {
1256	+	Collection<K> c = new ArrayList<K>();
1257	+	for (Iterator<K> i = iterator(); i.hasNext(); )
1258	+	c.add(i.next());
1259	+	return c.toArray(a);
1260	+	}
1261		}
1262
1263	<	private class Values extends AbstractCollection<V> {
1263	>	final class Values extends AbstractCollection<V> {
1264		public Iterator<V> iterator() {
1265		return new ValueIterator();
1266		}
#	Line 1044 | Line 1273 | public class ConcurrentHashMap<K, V> ext
1273		public void clear() {
1274		ConcurrentHashMap.this.clear();
1275		}
1276	+	public Object[] toArray() {
1277	+	Collection<V> c = new ArrayList<V>();
1278	+	for (Iterator<V> i = iterator(); i.hasNext(); )
1279	+	c.add(i.next());
1280	+	return c.toArray();
1281	+	}
1282	+	public <T> T[] toArray(T[] a) {
1283	+	Collection<V> c = new ArrayList<V>();
1284	+	for (Iterator<V> i = iterator(); i.hasNext(); )
1285	+	c.add(i.next());
1286	+	return c.toArray(a);
1287	+	}
1288		}
1289
1290	<	private class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1290	>	final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1291		public Iterator<Map.Entry<K,V>> iterator() {
1292		return new EntryIterator();
1293		}
#	Line 1069 | Line 1310 | public class ConcurrentHashMap<K, V> ext
1310		public void clear() {
1311		ConcurrentHashMap.this.clear();
1312		}
1313	+	public Object[] toArray() {
1314	+	// Since we don't ordinarily have distinct Entry objects, we
1315	+	// must pack elements using exportable SimpleEntry
1316	+	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
1317	+	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
1318	+	c.add(new AbstractMap.SimpleEntry<K,V>(i.next()));
1319	+	return c.toArray();
1320	+	}
1321	+	public <T> T[] toArray(T[] a) {
1322	+	Collection<Map.Entry<K,V>> c = new ArrayList<Map.Entry<K,V>>(size());
1323	+	for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); )
1324	+	c.add(new AbstractMap.SimpleEntry<K,V>(i.next()));
1325	+	return c.toArray(a);
1326	+	}
1327	+
1328		}
1329
1330		/* ---------------- Serialization Support -------------- */

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