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Comparing jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java (file contents):
Revision 1.228 by jsr166, Tue Jun 18 18:39:14 2013 UTC vs.
Revision 1.263 by jsr166, Sun Jan 4 01:17:26 2015 UTC

#	Line 10 | Line 10 | import java.io.ObjectStreamField;
10		import java.io.Serializable;
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;
15	–	import java.util.Comparator;
16	–	import java.util.ConcurrentModificationException;
16		import java.util.Enumeration;
17		import java.util.HashMap;
18		import java.util.Hashtable;
#	Line 22 | Line 21 | import java.util.Map;
21		import java.util.NoSuchElementException;
22		import java.util.Set;
23		import java.util.Spliterator;
25	–	import java.util.concurrent.ConcurrentMap;
26	–	import java.util.concurrent.ForkJoinPool;
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;
32	–	import java.util.function.BinaryOperator;
29		import java.util.function.Consumer;
30		import java.util.function.DoubleBinaryOperator;
31		import java.util.function.Function;
#	Line 64 | Line 60 | import java.util.stream.Stream;
60		* that key reporting the updated value.)  For aggregate operations
61		* such as {@code putAll} and {@code clear}, concurrent retrievals may
62		* reflect insertion or removal of only some entries.  Similarly,
63	<	* Iterators and Enumerations return elements reflecting the state of
64	<	* the hash table at some point at or since the creation of the
63	>	* Iterators, Spliterators and Enumerations return elements reflecting the
64	>	* state of the hash table at some point at or since the creation of the
65		* iterator/enumeration.  They do <em>not</em> throw {@link
66	<	* ConcurrentModificationException}.  However, iterators are designed
67	<	* to be used by only one thread at a time.  Bear in mind that the
68	<	* results of aggregate status methods including {@code size}, {@code
69	<	* isEmpty}, and {@code containsValue} are typically useful only when
70	<	* a map is not undergoing concurrent updates in other threads.
66	>	* java.util.ConcurrentModificationException ConcurrentModificationException}.
67	>	* However, iterators are designed to be used by only one thread at a time.
68	>	* Bear in mind that the results of aggregate status methods including
69	>	* {@code size}, {@code isEmpty}, and {@code containsValue} are typically
70	>	* useful only when a map is not undergoing concurrent updates in other threads.
71		* Otherwise the results of these methods reflect transient states
72		* that may be adequate for monitoring or estimation purposes, but not
73		* for program control.
#	Line 104 | Line 100 | import java.util.stream.Stream;
100		* mapped values are (perhaps transiently) not used or all take the
101		* same mapping value.
102		*
103	<	* <p>A ConcurrentHashMap can be used as scalable frequency map (a
103	>	* <p>A ConcurrentHashMap can be used as a scalable frequency map (a
104		* form of histogram or multiset) by using {@link
105		* java.util.concurrent.atomic.LongAdder} values and initializing via
106		* {@link #computeIfAbsent computeIfAbsent}. For example, to add a count
107		* to a {@code ConcurrentHashMap<String,LongAdder> freqs}, you can use
108	<	* {@code freqs.computeIfAbsent(k -> new LongAdder()).increment();}
108	>	* {@code freqs.computeIfAbsent(key, k -> new LongAdder()).increment();}
109		*
110		* <p>This class and its views and iterators implement all of the
111		* <em>optional</em> methods of the {@link Map} and {@link Iterator}
#	Line 131 | Line 127 | import java.util.stream.Stream;
127		* of supplied functions should not depend on any ordering, or on any
128		* other objects or values that may transiently change while
129		* computation is in progress; and except for forEach actions, should
130	<	* ideally be side-effect-free. Bulk operations on {@link Map.Entry}
130	>	* ideally be side-effect-free. Bulk operations on {@link java.util.Map.Entry}
131		* objects do not support method {@code setValue}.
132		*
133		* <ul>
#	Line 235 | Line 231 | import java.util.stream.Stream;
231		* @param <K> the type of keys maintained by this map
232		* @param <V> the type of mapped values
233		*/
234	<	public class ConcurrentHashMap<K,V> implements ConcurrentMap<K,V>, Serializable {
234	>	public class ConcurrentHashMap<K,V> extends AbstractMap<K,V>
235	>	implements ConcurrentMap<K,V>, Serializable {
236		private static final long serialVersionUID = 7249069246763182397L;
237
238		/*
#	Line 262 | Line 259 | public class ConcurrentHashMap<K,V> impl
259		* because they have negative hash fields and null key and value
260		* fields. (These special nodes are either uncommon or transient,
261		* so the impact of carrying around some unused fields is
262	<	* insignficant.)
262	>	* insignificant.)
263		*
264		* The table is lazily initialized to a power-of-two size upon the
265		* first insertion.  Each bin in the table normally contains a
#	Line 343 | Line 340 | public class ConcurrentHashMap<K,V> impl
340		* The table is resized when occupancy exceeds a percentage
341		* threshold (nominally, 0.75, but see below).  Any thread
342		* noticing an overfull bin may assist in resizing after the
343	<	* initiating thread allocates and sets up the replacement
344	<	* array. However, rather than stalling, these other threads may
345	<	* proceed with insertions etc.  The use of TreeBins shields us
346	<	* from the worst case effects of overfilling while resizes are in
343	>	* initiating thread allocates and sets up the replacement array.
344	>	* However, rather than stalling, these other threads may proceed
345	>	* with insertions etc.  The use of TreeBins shields us from the
346	>	* worst case effects of overfilling while resizes are in
347		* progress.  Resizing proceeds by transferring bins, one by one,
348	<	* from the table to the next table. To enable concurrency, the
349	<	* next table must be (incrementally) prefilled with place-holders
350	<	* serving as reverse forwarders to the old table.  Because we are
348	>	* from the table to the next table. However, threads claim small
349	>	* blocks of indices to transfer (via field transferIndex) before
350	>	* doing so, reducing contention.  A generation stamp in field
351	>	* sizeCtl ensures that resizings do not overlap. Because we are
352		* using power-of-two expansion, the elements from each bin must
353		* either stay at same index, or move with a power of two
354		* offset. We eliminate unnecessary node creation by catching
#	Line 371 | Line 369 | public class ConcurrentHashMap<K,V> impl
369		* locks, average aggregate waits become shorter as resizing
370		* progresses.  The transfer operation must also ensure that all
371		* accessible bins in both the old and new table are usable by any
372	<	* traversal.  This is arranged by proceeding from the last bin
373	<	* (table.length - 1) up towards the first.  Upon seeing a
374	<	* forwarding node, traversals (see class Traverser) arrange to
375	<	* move to the new table without revisiting nodes.  However, to
376	<	* ensure that no intervening nodes are skipped, bin splitting can
377	<	* only begin after the associated reverse-forwarders are in
378	<	* place.
372	>	* traversal.  This is arranged in part by proceeding from the
373	>	* last bin (table.length - 1) up towards the first.  Upon seeing
374	>	* a forwarding node, traversals (see class Traverser) arrange to
375	>	* move to the new table without revisiting nodes.  To ensure that
376	>	* no intervening nodes are skipped even when moved out of order,
377	>	* a stack (see class TableStack) is created on first encounter of
378	>	* a forwarding node during a traversal, to maintain its place if
379	>	* later processing the current table. The need for these
380	>	* save/restore mechanics is relatively rare, but when one
381	>	* forwarding node is encountered, typically many more will be.
382	>	* So Traversers use a simple caching scheme to avoid creating so
383	>	* many new TableStack nodes. (Thanks to Peter Levart for
384	>	* suggesting use of a stack here.)
385		*
386		* The traversal scheme also applies to partial traversals of
387		* ranges of bins (via an alternate Traverser constructor)
#	Line 409 | Line 413 | public class ConcurrentHashMap<K,V> impl
413		* related operations (which is the main reason we cannot use
414		* existing collections such as TreeMaps). TreeBins contain
415		* Comparable elements, but may contain others, as well as
416	<	* elements that are Comparable but not necessarily Comparable
417	<	* for the same T, so we cannot invoke compareTo among them. To
418	<	* handle this, the tree is ordered primarily by hash value, then
419	<	* by Comparable.compareTo order if applicable.  On lookup at a
420	<	* node, if elements are not comparable or compare as 0 then both
421	<	* left and right children may need to be searched in the case of
422	<	* tied hash values. (This corresponds to the full list search
423	<	* that would be necessary if all elements were non-Comparable and
424	<	* had tied hashes.)  The red-black balancing code is updated from
425	<	* pre-jdk-collections
416	>	* elements that are Comparable but not necessarily Comparable for
417	>	* the same T, so we cannot invoke compareTo among them. To handle
418	>	* this, the tree is ordered primarily by hash value, then by
419	>	* Comparable.compareTo order if applicable.  On lookup at a node,
420	>	* if elements are not comparable or compare as 0 then both left
421	>	* and right children may need to be searched in the case of tied
422	>	* hash values. (This corresponds to the full list search that
423	>	* would be necessary if all elements were non-Comparable and had
424	>	* tied hashes.) On insertion, to keep a total ordering (or as
425	>	* close as is required here) across rebalancings, we compare
426	>	* classes and identityHashCodes as tie-breakers. The red-black
427	>	* balancing code is updated from pre-jdk-collections
428		* (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java)
429		* based in turn on Cormen, Leiserson, and Rivest "Introduction to
430		* Algorithms" (CLR).
431		*
432		* TreeBins also require an additional locking mechanism.  While
433		* list traversal is always possible by readers even during
434	<	* updates, tree traversal is not, mainly beause of tree-rotations
434	>	* updates, tree traversal is not, mainly because of tree-rotations
435		* that may change the root node and/or its linkages.  TreeBins
436		* include a simple read-write lock mechanism parasitic on the
437		* main bin-synchronization strategy: Structural adjustments
#	Line 448 | Line 454 | public class ConcurrentHashMap<K,V> impl
454		* unused "Segment" class that is instantiated in minimal form
455		* only when serializing.
456		*
457	+	* Also, solely for compatibility with previous versions of this
458	+	* class, it extends AbstractMap, even though all of its methods
459	+	* are overridden, so it is just useless baggage.
460	+	*
461		* This file is organized to make things a little easier to follow
462		* while reading than they might otherwise: First the main static
463		* declarations and utilities, then fields, then main public
#	Line 528 | Line 538 | public class ConcurrentHashMap<K,V> impl
538		*/
539		private static final int MIN_TRANSFER_STRIDE = 16;
540
541	+	/**
542	+	* The number of bits used for generation stamp in sizeCtl.
543	+	* Must be at least 6 for 32bit arrays.
544	+	*/
545	+	private static int RESIZE_STAMP_BITS = 16;
546	+
547	+	/**
548	+	* The maximum number of threads that can help resize.
549	+	* Must fit in 32 - RESIZE_STAMP_BITS bits.
550	+	*/
551	+	private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1;
552	+
553	+	/**
554	+	* The bit shift for recording size stamp in sizeCtl.
555	+	*/
556	+	private static final int RESIZE_STAMP_SHIFT = 32 - RESIZE_STAMP_BITS;
557	+
558		/*
559		* Encodings for Node hash fields. See above for explanation.
560		*/
561	<	static final int MOVED     = 0x8fffffff; // (-1) hash for forwarding nodes
562	<	static final int TREEBIN   = 0x80000000; // hash for heads of treea
563	<	static final int RESERVED  = 0x80000001; // hash for transient reservations
561	>	static final int MOVED     = -1; // hash for forwarding nodes
562	>	static final int TREEBIN   = -2; // hash for roots of trees
563	>	static final int RESERVED  = -3; // hash for transient reservations
564		static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash
565
566		/** Number of CPUS, to place bounds on some sizings */
#	Line 552 | Line 579 | public class ConcurrentHashMap<K,V> impl
579		* Key-value entry.  This class is never exported out as a
580		* user-mutable Map.Entry (i.e., one supporting setValue; see
581		* MapEntry below), but can be used for read-only traversals used
582	<	* in bulk tasks.  Subclasses of Node with a negativehash field
582	>	* in bulk tasks.  Subclasses of Node with a negative hash field
583		* are special, and contain null keys and values (but are never
584		* exported).  Otherwise, keys and vals are never null.
585		*/
#	Line 560 | Line 587 | public class ConcurrentHashMap<K,V> impl
587		final int hash;
588		final K key;
589		volatile V val;
590	<	Node<K,V> next;
590	>	volatile Node<K,V> next;
591
592		Node(int hash, K key, V val, Node<K,V> next) {
593		this.hash = hash;
#	Line 685 | Line 712 | public class ConcurrentHashMap<K,V> impl
712		* errors by users, these checks must operate on local variables,
713		* which accounts for some odd-looking inline assignments below.
714		* Note that calls to setTabAt always occur within locked regions,
715	<	* and so do not need full volatile semantics, but still require
716	<	* ordering to maintain concurrent readability.
715	>	* and so in principle require only release ordering, not
716	>	* full volatile semantics, but are currently coded as volatile
717	>	* writes to be conservative.
718		*/
719
720		@SuppressWarnings("unchecked")
#	Line 700 | Line 728 | public class ConcurrentHashMap<K,V> impl
728		}
729
730		static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {
731	<	U.putOrderedObject(tab, ((long)i << ASHIFT) + ABASE, v);
731	>	U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);
732		}
733
734		/* ---------------- Fields -------------- */
#	Line 739 | Line 767 | public class ConcurrentHashMap<K,V> impl
767		private transient volatile int transferIndex;
768
769		/**
742	–	* The least available table index to split while resizing.
743	–	*/
744	–	private transient volatile int transferOrigin;
745	–
746	–	/**
770		* Spinlock (locked via CAS) used when resizing and/or creating CounterCells.
771		*/
772		private transient volatile int cellsBusy;
#	Line 1000 | Line 1023 | public class ConcurrentHashMap<K,V> impl
1023		p.val = value;
1024		}
1025		}
1026	+	else if (f instanceof ReservationNode)
1027	+	throw new IllegalStateException("Recursive update");
1028		}
1029		}
1030		if (binCount != 0) {
#	Line 1102 | Line 1127 | public class ConcurrentHashMap<K,V> impl
1127		}
1128		}
1129		}
1130	+	else if (f instanceof ReservationNode)
1131	+	throw new IllegalStateException("Recursive update");
1132		}
1133		}
1134		if (validated) {
#	Line 1162 | Line 1189 | public class ConcurrentHashMap<K,V> impl
1189		* operations.  It does not support the {@code add} or
1190		* {@code addAll} operations.
1191		*
1192	<	* <p>The view's {@code iterator} is a "weakly consistent" iterator
1193	<	* that will never throw {@link ConcurrentModificationException},
1194	<	* and guarantees to traverse elements as they existed upon
1195	<	* construction of the iterator, and may (but is not guaranteed to)
1196	<	* reflect any modifications subsequent to construction.
1192	>	* <p>The view's iterators and spliterators are
1193	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1194	>	*
1195	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
1196	>	* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
1197		*
1198		* @return the set view
1199		*/
#	Line 1185 | Line 1212 | public class ConcurrentHashMap<K,V> impl
1212		* {@code retainAll}, and {@code clear} operations.  It does not
1213		* support the {@code add} or {@code addAll} operations.
1214		*
1215	<	* <p>The view's {@code iterator} is a "weakly consistent" iterator
1216	<	* that will never throw {@link ConcurrentModificationException},
1217	<	* and guarantees to traverse elements as they existed upon
1218	<	* construction of the iterator, and may (but is not guaranteed to)
1219	<	* reflect any modifications subsequent to construction.
1215	>	* <p>The view's iterators and spliterators are
1216	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1217	>	*
1218	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT}
1219	>	* and {@link Spliterator#NONNULL}.
1220		*
1221		* @return the collection view
1222		*/
#	Line 1207 | Line 1234 | public class ConcurrentHashMap<K,V> impl
1234		* {@code removeAll}, {@code retainAll}, and {@code clear}
1235		* operations.
1236		*
1237	<	* <p>The view's {@code iterator} is a "weakly consistent" iterator
1238	<	* that will never throw {@link ConcurrentModificationException},
1239	<	* and guarantees to traverse elements as they existed upon
1240	<	* construction of the iterator, and may (but is not guaranteed to)
1241	<	* reflect any modifications subsequent to construction.
1237	>	* <p>The view's iterators and spliterators are
1238	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
1239	>	*
1240	>	* <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
1241	>	* {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
1242		*
1243		* @return the set view
1244		*/
#	Line 1321 | Line 1348 | public class ConcurrentHashMap<K,V> impl
1348		* Saves the state of the {@code ConcurrentHashMap} instance to a
1349		* stream (i.e., serializes it).
1350		* @param s the stream
1351	+	* @throws java.io.IOException if an I/O error occurs
1352		* @serialData
1353		* the key (Object) and value (Object)
1354		* for each key-value mapping, followed by a null pair.
#	Line 1338 | Line 1366 | public class ConcurrentHashMap<K,V> impl
1366		}
1367		int segmentShift = 32 - sshift;
1368		int segmentMask = ssize - 1;
1369	<	@SuppressWarnings("unchecked") Segment<K,V>[] segments = (Segment<K,V>[])
1369	>	@SuppressWarnings("unchecked")
1370	>	Segment<K,V>[] segments = (Segment<K,V>[])
1371		new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL];
1372		for (int i = 0; i < segments.length; ++i)
1373		segments[i] = new Segment<K,V>(LOAD_FACTOR);
#	Line 1363 | Line 1392 | public class ConcurrentHashMap<K,V> impl
1392		/**
1393		* Reconstitutes the instance from a stream (that is, deserializes it).
1394		* @param s the stream
1395	+	* @throws ClassNotFoundException if the class of a serialized object
1396	+	*         could not be found
1397	+	* @throws java.io.IOException if an I/O error occurs
1398		*/
1399		private void readObject(java.io.ObjectInputStream s)
1400		throws java.io.IOException, ClassNotFoundException {
#	Line 1378 | Line 1410 | public class ConcurrentHashMap<K,V> impl
1410		long size = 0L;
1411		Node<K,V> p = null;
1412		for (;;) {
1413	<	@SuppressWarnings("unchecked") K k = (K) s.readObject();
1414	<	@SuppressWarnings("unchecked") V v = (V) s.readObject();
1413	>	@SuppressWarnings("unchecked")
1414	>	K k = (K) s.readObject();
1415	>	@SuppressWarnings("unchecked")
1416	>	V v = (V) s.readObject();
1417		if (k != null && v != null) {
1418		p = new Node<K,V>(spread(k.hashCode()), k, v, p);
1419		++size;
#	Line 1397 | Line 1431 | public class ConcurrentHashMap<K,V> impl
1431		int sz = (int)size;
1432		n = tableSizeFor(sz + (sz >>> 1) + 1);
1433		}
1434	<	@SuppressWarnings({"rawtypes","unchecked"})
1435	<	Node<K,V>[] tab = (Node<K,V>[])new Node[n];
1434	>	@SuppressWarnings("unchecked")
1435	>	Node<K,V>[] tab = (Node<K,V>[])new Node<?,?>[n];
1436		int mask = n - 1;
1437		long added = 0L;
1438		while (p != null) {
#	Line 1623 | Line 1657 | public class ConcurrentHashMap<K,V> impl
1657		Node<K,V> pred = e;
1658		if ((e = e.next) == null) {
1659		if ((val = mappingFunction.apply(key)) != null) {
1660	+	if (pred.next != null)
1661	+	throw new IllegalStateException("Recursive update");
1662		added = true;
1663		pred.next = new Node<K,V>(h, key, val, null);
1664		}
#	Line 1642 | Line 1678 | public class ConcurrentHashMap<K,V> impl
1678		t.putTreeVal(h, key, val);
1679		}
1680		}
1681	+	else if (f instanceof ReservationNode)
1682	+	throw new IllegalStateException("Recursive update");
1683		}
1684		}
1685		if (binCount != 0) {
#	Line 1737 | Line 1775 | public class ConcurrentHashMap<K,V> impl
1775		}
1776		}
1777		}
1778	+	else if (f instanceof ReservationNode)
1779	+	throw new IllegalStateException("Recursive update");
1780		}
1781		}
1782		if (binCount != 0)
#	Line 1828 | Line 1868 | public class ConcurrentHashMap<K,V> impl
1868		if ((e = e.next) == null) {
1869		val = remappingFunction.apply(key, null);
1870		if (val != null) {
1871	+	if (pred.next != null)
1872	+	throw new IllegalStateException("Recursive update");
1873		delta = 1;
1874		pred.next =
1875		new Node<K,V>(h, key, val, null);
#	Line 1860 | Line 1902 | public class ConcurrentHashMap<K,V> impl
1902		setTabAt(tab, i, untreeify(t.first));
1903		}
1904		}
1905	+	else if (f instanceof ReservationNode)
1906	+	throw new IllegalStateException("Recursive update");
1907		}
1908		}
1909		if (binCount != 0) {
#	Line 1969 | Line 2013 | public class ConcurrentHashMap<K,V> impl
2013		setTabAt(tab, i, untreeify(t.first));
2014		}
2015		}
2016	+	else if (f instanceof ReservationNode)
2017	+	throw new IllegalStateException("Recursive update");
2018		}
2019		}
2020		if (binCount != 0) {
#	Line 1987 | Line 2033 | public class ConcurrentHashMap<K,V> impl
2033
2034		/**
2035		* Legacy method testing if some key maps into the specified value
2036	<	* in this table.  This method is identical in functionality to
2036	>	* in this table.
2037	>	*
2038	>	* @deprecated This method is identical in functionality to
2039		* {@link #containsValue(Object)}, and exists solely to ensure
2040		* full compatibility with class {@link java.util.Hashtable},
2041		* which supported this method prior to introduction of the
#	Line 2000 | Line 2048 | public class ConcurrentHashMap<K,V> impl
2048		*         {@code false} otherwise
2049		* @throws NullPointerException if the specified value is null
2050		*/
2051	<	@Deprecated public boolean contains(Object value) {
2051	>	@Deprecated
2052	>	public boolean contains(Object value) {
2053		return containsValue(value);
2054		}
2055
#	Line 2049 | Line 2098 | public class ConcurrentHashMap<K,V> impl
2098		* Creates a new {@link Set} backed by a ConcurrentHashMap
2099		* from the given type to {@code Boolean.TRUE}.
2100		*
2101	+	* @param <K> the element type of the returned set
2102		* @return the new set
2103		* @since 1.8
2104		*/
#	Line 2063 | Line 2113 | public class ConcurrentHashMap<K,V> impl
2113		*
2114		* @param initialCapacity The implementation performs internal
2115		* sizing to accommodate this many elements.
2116	+	* @param <K> the element type of the returned set
2117	+	* @return the new set
2118		* @throws IllegalArgumentException if the initial capacity of
2119		* elements is negative
2068	–	* @return the new set
2120		* @since 1.8
2121		*/
2122		public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) {
#	Line 2103 | Line 2154 | public class ConcurrentHashMap<K,V> impl
2154		}
2155
2156		Node<K,V> find(int h, Object k) {
2157	<	Node<K,V> e; int n;
2158	<	Node<K,V>[] tab = nextTable;
2159	<	if (k != null && tab != null && (n = tab.length) > 0 &&
2160	<	(e = tabAt(tab, (n - 1) & h)) != null) {
2161	<	do {
2157	>	// loop to avoid arbitrarily deep recursion on forwarding nodes
2158	>	outer: for (Node<K,V>[] tab = nextTable;;) {
2159	>	Node<K,V> e; int n;
2160	>	if (k == null || tab == null || (n = tab.length) == 0 ||
2161	>	(e = tabAt(tab, (n - 1) & h)) == null)
2162	>	return null;
2163	>	for (;;) {
2164		int eh; K ek;
2165		if ((eh = e.hash) == h &&
2166		((ek = e.key) == k || (ek != null && k.equals(ek))))
2167		return e;
2168	<	if (eh < 0)
2169	<	return e.find(h, k);
2170	<	} while ((e = e.next) != null);
2168	>	if (eh < 0) {
2169	>	if (e instanceof ForwardingNode) {
2170	>	tab = ((ForwardingNode<K,V>)e).nextTable;
2171	>	continue outer;
2172	>	}
2173	>	else
2174	>	return e.find(h, k);
2175	>	}
2176	>	if ((e = e.next) == null)
2177	>	return null;
2178	>	}
2179		}
2119	–	return null;
2180		}
2181		}
2182
#	Line 2136 | Line 2196 | public class ConcurrentHashMap<K,V> impl
2196		/* ---------------- Table Initialization and Resizing -------------- */
2197
2198		/**
2199	+	* Returns the stamp bits for resizing a table of size n.
2200	+	* Must be negative when shifted left by RESIZE_STAMP_SHIFT.
2201	+	*/
2202	+	static final int resizeStamp(int n) {
2203	+	return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1));
2204	+	}
2205	+
2206	+	/**
2207		* Initializes table, using the size recorded in sizeCtl.
2208		*/
2209		private final Node<K,V>[] initTable() {
#	Line 2147 | Line 2215 | public class ConcurrentHashMap<K,V> impl
2215		try {
2216		if ((tab = table) == null || tab.length == 0) {
2217		int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
2218	<	@SuppressWarnings({"rawtypes","unchecked"})
2219	<	Node<K,V>[] nt = (Node<K,V>[])new Node[n];
2218	>	@SuppressWarnings("unchecked")
2219	>	Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
2220		table = tab = nt;
2221		sc = n - (n >>> 2);
2222		}
#	Line 2189 | Line 2257 | public class ConcurrentHashMap<K,V> impl
2257		s = sumCount();
2258		}
2259		if (check >= 0) {
2260	<	Node<K,V>[] tab, nt; int sc;
2260	>	Node<K,V>[] tab, nt; int n, sc;
2261		while (s >= (long)(sc = sizeCtl) && (tab = table) != null &&
2262	<	tab.length < MAXIMUM_CAPACITY) {
2262	>	(n = tab.length) < MAXIMUM_CAPACITY) {
2263	>	int rs = resizeStamp(n);
2264		if (sc < 0) {
2265	<	if (sc == -1 || transferIndex <= transferOrigin ||
2266	<	(nt = nextTable) == null)
2265	>	if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
2266	>	sc == rs + MAX_RESIZERS || (nt = nextTable) == null ||
2267	>	transferIndex <= 0)
2268		break;
2269	<	if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2269	>	if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1))
2270		transfer(tab, nt);
2271		}
2272	<	else if (U.compareAndSwapInt(this, SIZECTL, sc, -2))
2272	>	else if (U.compareAndSwapInt(this, SIZECTL, sc,
2273	>	(rs << RESIZE_STAMP_SHIFT) + 2))
2274		transfer(tab, null);
2275		s = sumCount();
2276		}
#	Line 2211 | Line 2282 | public class ConcurrentHashMap<K,V> impl
2282		*/
2283		final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) {
2284		Node<K,V>[] nextTab; int sc;
2285	<	if ((f instanceof ForwardingNode) &&
2285	>	if (tab != null && (f instanceof ForwardingNode) &&
2286		(nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) {
2287	<	if (nextTab == nextTable && tab == table &&
2288	<	transferIndex > transferOrigin && (sc = sizeCtl) < -1 &&
2289	<	U.compareAndSwapInt(this, SIZECTL, sc, sc - 1))
2290	<	transfer(tab, nextTab);
2287	>	int rs = resizeStamp(tab.length);
2288	>	while (nextTab == nextTable && table == tab &&
2289	>	(sc = sizeCtl) < 0) {
2290	>	if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 ||
2291	>	sc == rs + MAX_RESIZERS || transferIndex <= 0)
2292	>	break;
2293	>	if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) {
2294	>	transfer(tab, nextTab);
2295	>	break;
2296	>	}
2297	>	}
2298		return nextTab;
2299		}
2300		return table;
#	Line 2238 | Line 2316 | public class ConcurrentHashMap<K,V> impl
2316		if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
2317		try {
2318		if (table == tab) {
2319	<	@SuppressWarnings({"rawtypes","unchecked"})
2320	<	Node<K,V>[] nt = (Node<K,V>[])new Node[n];
2319	>	@SuppressWarnings("unchecked")
2320	>	Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n];
2321		table = nt;
2322		sc = n - (n >>> 2);
2323		}
#	Line 2250 | Line 2328 | public class ConcurrentHashMap<K,V> impl
2328		}
2329		else if (c <= sc || n >= MAXIMUM_CAPACITY)
2330		break;
2331	<	else if (tab == table &&
2332	<	U.compareAndSwapInt(this, SIZECTL, sc, -2))
2333	<	transfer(tab, null);
2331	>	else if (tab == table) {
2332	>	int rs = resizeStamp(n);
2333	>	if (U.compareAndSwapInt(this, SIZECTL, sc,
2334	>	(rs << RESIZE_STAMP_SHIFT) + 2))
2335	>	transfer(tab, null);
2336	>	}
2337		}
2338		}
2339
#	Line 2266 | Line 2347 | public class ConcurrentHashMap<K,V> impl
2347		stride = MIN_TRANSFER_STRIDE; // subdivide range
2348		if (nextTab == null) {            // initiating
2349		try {
2350	<	@SuppressWarnings({"rawtypes","unchecked"})
2351	<	Node<K,V>[] nt = (Node<K,V>[])new Node[n << 1];
2350	>	@SuppressWarnings("unchecked")
2351	>	Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n << 1];
2352		nextTab = nt;
2353		} catch (Throwable ex) {      // try to cope with OOME
2354		sizeCtl = Integer.MAX_VALUE;
2355		return;
2356		}
2357		nextTable = nextTab;
2277	–	transferOrigin = n;
2358		transferIndex = n;
2279	–	ForwardingNode<K,V> rev = new ForwardingNode<K,V>(tab);
2280	–	for (int k = n; k > 0;) {    // progressively reveal ready slots
2281	–	int nextk = (k > stride) ? k - stride : 0;
2282	–	for (int m = nextk; m < k; ++m)
2283	–	nextTab[m] = rev;
2284	–	for (int m = n + nextk; m < n + k; ++m)
2285	–	nextTab[m] = rev;
2286	–	U.putOrderedInt(this, TRANSFERORIGIN, k = nextk);
2287	–	}
2359		}
2360		int nextn = nextTab.length;
2361		ForwardingNode<K,V> fwd = new ForwardingNode<K,V>(nextTab);
2362		boolean advance = true;
2363	+	boolean finishing = false; // to ensure sweep before committing nextTab
2364		for (int i = 0, bound = 0;;) {
2365	<	int nextIndex, nextBound, fh; Node<K,V> f;
2365	>	Node<K,V> f; int fh;
2366		while (advance) {
2367	<	if (--i >= bound)
2367	>	int nextIndex, nextBound;
2368	>	if (--i >= bound || finishing)
2369		advance = false;
2370	<	else if ((nextIndex = transferIndex) <= transferOrigin) {
2370	>	else if ((nextIndex = transferIndex) <= 0) {
2371		i = -1;
2372		advance = false;
2373		}
#	Line 2308 | Line 2381 | public class ConcurrentHashMap<K,V> impl
2381		}
2382		}
2383		if (i < 0 || i >= n || i + n >= nextn) {
2384	<	for (int sc;;) {
2385	<	if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) {
2386	<	if (sc == -1) {
2387	<	nextTable = null;
2388	<	table = nextTab;
2389	<	sizeCtl = (n << 1) - (n >>> 1);
2317	<	}
2318	<	return;
2319	<	}
2384	>	int sc;
2385	>	if (finishing) {
2386	>	nextTable = null;
2387	>	table = nextTab;
2388	>	sizeCtl = (n << 1) - (n >>> 1);
2389	>	return;
2390		}
2391	<	}
2392	<	else if ((f = tabAt(tab, i)) == null) {
2393	<	if (casTabAt(tab, i, null, fwd)) {
2394	<	setTabAt(nextTab, i, null);
2395	<	setTabAt(nextTab, i + n, null);
2326	<	advance = true;
2391	>	if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, sc - 1)) {
2392	>	if ((sc - 2) != resizeStamp(n) << RESIZE_STAMP_SHIFT)
2393	>	return;
2394	>	finishing = advance = true;
2395	>	i = n; // recheck before commit
2396		}
2397		}
2398	+	else if ((f = tabAt(tab, i)) == null)
2399	+	advance = casTabAt(tab, i, null, fwd);
2400		else if ((fh = f.hash) == MOVED)
2401		advance = true; // already processed
2402		else {
#	Line 2357 | Line 2428 | public class ConcurrentHashMap<K,V> impl
2428		else
2429		hn = new Node<K,V>(ph, pk, pv, hn);
2430		}
2431	+	setTabAt(nextTab, i, ln);
2432	+	setTabAt(nextTab, i + n, hn);
2433	+	setTabAt(tab, i, fwd);
2434	+	advance = true;
2435		}
2436		else if (f instanceof TreeBin) {
2437		TreeBin<K,V> t = (TreeBin<K,V>)f;
#	Line 2388 | Line 2463 | public class ConcurrentHashMap<K,V> impl
2463		(hc != 0) ? new TreeBin<K,V>(lo) : t;
2464		hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) :
2465		(lc != 0) ? new TreeBin<K,V>(hi) : t;
2466	+	setTabAt(nextTab, i, ln);
2467	+	setTabAt(nextTab, i + n, hn);
2468	+	setTabAt(tab, i, fwd);
2469	+	advance = true;
2470		}
2392	–	else
2393	–	ln = hn = null;
2394	–	setTabAt(nextTab, i, ln);
2395	–	setTabAt(nextTab, i + n, hn);
2396	–	setTabAt(tab, i, fwd);
2397	–	advance = true;
2471		}
2472		}
2473		}
#	Line 2515 | Line 2588 | public class ConcurrentHashMap<K,V> impl
2588		private final void treeifyBin(Node<K,V>[] tab, int index) {
2589		Node<K,V> b; int n, sc;
2590		if (tab != null) {
2591	<	if ((n = tab.length) < MIN_TREEIFY_CAPACITY) {
2592	<	if (tab == table && (sc = sizeCtl) >= 0 &&
2593	<	U.compareAndSwapInt(this, SIZECTL, sc, -2))
2521	<	transfer(tab, null);
2522	<	}
2523	<	else if ((b = tabAt(tab, index)) != null) {
2591	>	if ((n = tab.length) < MIN_TREEIFY_CAPACITY)
2592	>	tryPresize(n << 1);
2593	>	else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
2594		synchronized (b) {
2595		if (tabAt(tab, index) == b) {
2596		TreeNode<K,V> hd = null, tl = null;
#	Line 2542 | Line 2612 | public class ConcurrentHashMap<K,V> impl
2612		}
2613
2614		/**
2615	<	* Returns a list on non-TreeNodes replacing those in given list
2615	>	* Returns a list on non-TreeNodes replacing those in given list.
2616		*/
2617		static <K,V> Node<K,V> untreeify(Node<K,V> b) {
2618		Node<K,V> hd = null, tl = null;
#	Line 2586 | Line 2656 | public class ConcurrentHashMap<K,V> impl
2656		final TreeNode<K,V> findTreeNode(int h, Object k, Class<?> kc) {
2657		if (k != null) {
2658		TreeNode<K,V> p = this;
2659	<	do  {
2659	>	do {
2660		int ph, dir; K pk; TreeNode<K,V> q;
2661		TreeNode<K,V> pl = p.left, pr = p.right;
2662		if ((ph = p.hash) > h)
#	Line 2595 | Line 2665 | public class ConcurrentHashMap<K,V> impl
2665		p = pr;
2666		else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
2667		return p;
2668	<	else if (pl == null && pr == null)
2669	<	break;
2668	>	else if (pl == null)
2669	>	p = pr;
2670	>	else if (pr == null)
2671	>	p = pl;
2672		else if ((kc != null ||
2673		(kc = comparableClassFor(k)) != null) &&
2674		(dir = compareComparables(kc, k, pk)) != 0)
2675		p = (dir < 0) ? pl : pr;
2676	<	else if (pl == null)
2605	<	p = pr;
2606	<	else if (pr == null ||
2607	<	(q = pr.findTreeNode(h, k, kc)) == null)
2608	<	p = pl;
2609	<	else
2676	>	else if ((q = pr.findTreeNode(h, k, kc)) != null)
2677		return q;
2678	+	else
2679	+	p = pl;
2680		} while (p != null);
2681		}
2682		return null;
#	Line 2634 | Line 2703 | public class ConcurrentHashMap<K,V> impl
2703		static final int READER = 4; // increment value for setting read lock
2704
2705		/**
2706	+	* Tie-breaking utility for ordering insertions when equal
2707	+	* hashCodes and non-comparable. We don't require a total
2708	+	* order, just a consistent insertion rule to maintain
2709	+	* equivalence across rebalancings. Tie-breaking further than
2710	+	* necessary simplifies testing a bit.
2711	+	*/
2712	+	static int tieBreakOrder(Object a, Object b) {
2713	+	int d;
2714	+	if (a == null || b == null ||
2715	+	(d = a.getClass().getName().
2716	+	compareTo(b.getClass().getName())) == 0)
2717	+	d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
2718	+	-1 : 1);
2719	+	return d;
2720	+	}
2721	+
2722	+	/**
2723		* Creates bin with initial set of nodes headed by b.
2724		*/
2725		TreeBin(TreeNode<K,V> b) {
#	Line 2649 | Line 2735 | public class ConcurrentHashMap<K,V> impl
2735		r = x;
2736		}
2737		else {
2738	<	Object key = x.key;
2739	<	int hash = x.hash;
2738	>	K k = x.key;
2739	>	int h = x.hash;
2740		Class<?> kc = null;
2741		for (TreeNode<K,V> p = r;;) {
2742		int dir, ph;
2743	<	if ((ph = p.hash) > hash)
2743	>	K pk = p.key;
2744	>	if ((ph = p.hash) > h)
2745		dir = -1;
2746	<	else if (ph < hash)
2746	>	else if (ph < h)
2747		dir = 1;
2748	<	else if ((kc != null ||
2749	<	(kc = comparableClassFor(key)) != null))
2750	<	dir = compareComparables(kc, key, p.key);
2751	<	else
2665	<	dir = 0;
2748	>	else if ((kc == null &&
2749	>	(kc = comparableClassFor(k)) == null) ||
2750	>	(dir = compareComparables(kc, k, pk)) == 0)
2751	>	dir = tieBreakOrder(k, pk);
2752		TreeNode<K,V> xp = p;
2753		if ((p = (dir <= 0) ? p.left : p.right) == null) {
2754		x.parent = xp;
#	Line 2677 | Line 2763 | public class ConcurrentHashMap<K,V> impl
2763		}
2764		}
2765		this.root = r;
2766	+	assert checkInvariants(root);
2767		}
2768
2769		/**
2770	<	* Acquires write lock for tree restructuring
2770	>	* Acquires write lock for tree restructuring.
2771		*/
2772		private final void lockRoot() {
2773		if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER))
#	Line 2688 | Line 2775 | public class ConcurrentHashMap<K,V> impl
2775		}
2776
2777		/**
2778	<	* Releases write lock for tree restructuring
2778	>	* Releases write lock for tree restructuring.
2779		*/
2780		private final void unlockRoot() {
2781		lockState = 0;
2782		}
2783
2784		/**
2785	<	* Possibly blocks awaiting root lock
2785	>	* Possibly blocks awaiting root lock.
2786		*/
2787		private final void contendedLock() {
2788		boolean waiting = false;
2789		for (int s;;) {
2790	<	if (((s = lockState) & WRITER) == 0) {
2790	>	if (((s = lockState) & ~WAITER) == 0) {
2791		if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
2792		if (waiting)
2793		waiter = null;
2794		return;
2795		}
2796		}
2797	<	else if ((s | WAITER) == 0) {
2797	>	else if ((s & WAITER) == 0) {
2798		if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
2799		waiting = true;
2800		waiter = Thread.currentThread();
#	Line 2720 | Line 2807 | public class ConcurrentHashMap<K,V> impl
2807
2808		/**
2809		* Returns matching node or null if none. Tries to search
2810	<	* using tree compareisons from root, but continues linear
2810	>	* using tree comparisons from root, but continues linear
2811		* search when lock not available.
2812		*/
2813		final Node<K,V> find(int h, Object k) {
2814		if (k != null) {
2815	<	for (Node<K,V> e = first; e != null; e = e.next) {
2815	>	for (Node<K,V> e = first; e != null; ) {
2816		int s; K ek;
2817		if (((s = lockState) & (WAITER|WRITER)) != 0) {
2818		if (e.hash == h &&
2819		((ek = e.key) == k || (ek != null && k.equals(ek))))
2820		return e;
2821	+	e = e.next;
2822		}
2823		else if (U.compareAndSwapInt(this, LOCKSTATE, s,
2824		s + READER)) {
#	Line 2757 | Line 2845 | public class ConcurrentHashMap<K,V> impl
2845		*/
2846		final TreeNode<K,V> putTreeVal(int h, K k, V v) {
2847		Class<?> kc = null;
2848	+	boolean searched = false;
2849		for (TreeNode<K,V> p = root;;) {
2850	<	int dir, ph; K pk; TreeNode<K,V> q, pr;
2850	>	int dir, ph; K pk;
2851		if (p == null) {
2852		first = root = new TreeNode<K,V>(h, k, v, null, null);
2853		break;
#	Line 2772 | Line 2861 | public class ConcurrentHashMap<K,V> impl
2861		else if ((kc == null &&
2862		(kc = comparableClassFor(k)) == null) ||
2863		(dir = compareComparables(kc, k, pk)) == 0) {
2864	<	if (p.left == null)
2865	<	dir = 1;
2866	<	else if ((pr = p.right) == null ||
2867	<	(q = pr.findTreeNode(h, k, kc)) == null)
2868	<	dir = -1;
2869	<	else
2870	<	return q;
2864	>	if (!searched) {
2865	>	TreeNode<K,V> q, ch;
2866	>	searched = true;
2867	>	if (((ch = p.left) != null &&
2868	>	(q = ch.findTreeNode(h, k, kc)) != null) ||
2869	>	((ch = p.right) != null &&
2870	>	(q = ch.findTreeNode(h, k, kc)) != null))
2871	>	return q;
2872	>	}
2873	>	dir = tieBreakOrder(k, pk);
2874		}
2875	+
2876		TreeNode<K,V> xp = p;
2877	<	if ((p = (dir < 0) ? p.left : p.right) == null) {
2877	>	if ((p = (dir <= 0) ? p.left : p.right) == null) {
2878		TreeNode<K,V> x, f = first;
2879		first = x = new TreeNode<K,V>(h, k, v, f, xp);
2880		if (f != null)
2881		f.prev = x;
2882	<	if (dir < 0)
2882	>	if (dir <= 0)
2883		xp.left = x;
2884		else
2885		xp.right = x;
#	Line 2815 | Line 2908 | public class ConcurrentHashMap<K,V> impl
2908		* that are accessible independently of lock. So instead we
2909		* swap the tree linkages.
2910		*
2911	<	* @return true if now too small so should be untreeified.
2911	>	* @return true if now too small, so should be untreeified
2912		*/
2913		final boolean removeTreeNode(TreeNode<K,V> p) {
2914		TreeNode<K,V> next = (TreeNode<K,V>)p.next;
#	Line 3009 | Line 3102 | public class ConcurrentHashMap<K,V> impl
3102
3103		static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
3104		TreeNode<K,V> x) {
3105	<	for (TreeNode<K,V> xp, xpl, xpr;;)  {
3105	>	for (TreeNode<K,V> xp, xpl, xpr;;) {
3106		if (x == null || x == root)
3107		return root;
3108		else if ((xp = x.parent) == null) {
#	Line 3132 | Line 3225 | public class ConcurrentHashMap<K,V> impl
3225		Class<?> k = TreeBin.class;
3226		LOCKSTATE = U.objectFieldOffset
3227		(k.getDeclaredField("lockState"));
3228	<	} catch (Exception e) {
3228	>	} catch (ReflectiveOperationException e) {
3229		throw new Error(e);
3230		}
3231		}
#	Line 3141 | Line 3234 | public class ConcurrentHashMap<K,V> impl
3234		/* ----------------Table Traversal -------------- */
3235
3236		/**
3237	+	* Records the table, its length, and current traversal index for a
3238	+	* traverser that must process a region of a forwarded table before
3239	+	* proceeding with current table.
3240	+	*/
3241	+	static final class TableStack<K,V> {
3242	+	int length;
3243	+	int index;
3244	+	Node<K,V>[] tab;
3245	+	TableStack<K,V> next;
3246	+	}
3247	+
3248	+	/**
3249		* Encapsulates traversal for methods such as containsValue; also
3250		* serves as a base class for other iterators and spliterators.
3251		*
#	Line 3164 | Line 3269 | public class ConcurrentHashMap<K,V> impl
3269		static class Traverser<K,V> {
3270		Node<K,V>[] tab;        // current table; updated if resized
3271		Node<K,V> next;         // the next entry to use
3272	+	TableStack<K,V> stack, spare; // to save/restore on ForwardingNodes
3273		int index;              // index of bin to use next
3274		int baseIndex;          // current index of initial table
3275		int baseLimit;          // index bound for initial table
#	Line 3185 | Line 3291 | public class ConcurrentHashMap<K,V> impl
3291		if ((e = next) != null)
3292		e = e.next;
3293		for (;;) {
3294	<	Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
3294	>	Node<K,V>[] t; int i, n;  // must use locals in checks
3295		if (e != null)
3296		return next = e;
3297		if (baseIndex >= baseLimit || (t = tab) == null ||
3298		(n = t.length) <= (i = index) || i < 0)
3299		return next = null;
3300	<	if ((e = tabAt(t, index)) != null && e.hash < 0) {
3300	>	if ((e = tabAt(t, i)) != null && e.hash < 0) {
3301		if (e instanceof ForwardingNode) {
3302		tab = ((ForwardingNode<K,V>)e).nextTable;
3303		e = null;
3304	+	pushState(t, i, n);
3305		continue;
3306		}
3307		else if (e instanceof TreeBin)
#	Line 3202 | Line 3309 | public class ConcurrentHashMap<K,V> impl
3309		else
3310		e = null;
3311		}
3312	<	if ((index += baseSize) >= n)
3313	<	index = ++baseIndex;    // visit upper slots if present
3312	>	if (stack != null)
3313	>	recoverState(n);
3314	>	else if ((index = i + baseSize) >= n)
3315	>	index = ++baseIndex; // visit upper slots if present
3316		}
3317		}
3318	+
3319	+	/**
3320	+	* Saves traversal state upon encountering a forwarding node.
3321	+	*/
3322	+	private void pushState(Node<K,V>[] t, int i, int n) {
3323	+	TableStack<K,V> s = spare;  // reuse if possible
3324	+	if (s != null)
3325	+	spare = s.next;
3326	+	else
3327	+	s = new TableStack<K,V>();
3328	+	s.tab = t;
3329	+	s.length = n;
3330	+	s.index = i;
3331	+	s.next = stack;
3332	+	stack = s;
3333	+	}
3334	+
3335	+	/**
3336	+	* Possibly pops traversal state.
3337	+	*
3338	+	* @param n length of current table
3339	+	*/
3340	+	private void recoverState(int n) {
3341	+	TableStack<K,V> s; int len;
3342	+	while ((s = stack) != null && (index += (len = s.length)) >= n) {
3343	+	n = len;
3344	+	index = s.index;
3345	+	tab = s.tab;
3346	+	s.tab = null;
3347	+	TableStack<K,V> next = s.next;
3348	+	s.next = spare; // save for reuse
3349	+	stack = next;
3350	+	spare = s;
3351	+	}
3352	+	if (s == null && (index += baseSize) >= n)
3353	+	index = ++baseIndex;
3354	+	}
3355		}
3356
3357		/**
3358		* Base of key, value, and entry Iterators. Adds fields to
3359	<	* Traverser to support iterator.remove
3359	>	* Traverser to support iterator.remove.
3360		*/
3361		static class BaseIterator<K,V> extends Traverser<K,V> {
3362		final ConcurrentHashMap<K,V> map;
#	Line 3498 | Line 3644 | public class ConcurrentHashMap<K,V> impl
3644		* for an element, or null if there is no transformation (in
3645		* which case the action is not applied)
3646		* @param action the action
3647	+	* @param <U> the return type of the transformer
3648		* @since 1.8
3649		*/
3650		public <U> void forEach(long parallelismThreshold,
#	Line 3521 | Line 3668 | public class ConcurrentHashMap<K,V> impl
3668		* needed for this operation to be executed in parallel
3669		* @param searchFunction a function returning a non-null
3670		* result on success, else null
3671	+	* @param <U> the return type of the search function
3672		* @return a non-null result from applying the given search
3673		* function on each (key, value), or null if none
3674		* @since 1.8
#	Line 3544 | Line 3692 | public class ConcurrentHashMap<K,V> impl
3692		* for an element, or null if there is no transformation (in
3693		* which case it is not combined)
3694		* @param reducer a commutative associative combining function
3695	+	* @param <U> the return type of the transformer
3696		* @return the result of accumulating the given transformation
3697		* of all (key, value) pairs
3698		* @since 1.8
#	Line 3573 | Line 3722 | public class ConcurrentHashMap<K,V> impl
3722		* of all (key, value) pairs
3723		* @since 1.8
3724		*/
3725	<	public double reduceToDoubleIn(long parallelismThreshold,
3726	<	ToDoubleBiFunction<? super K, ? super V> transformer,
3727	<	double basis,
3728	<	DoubleBinaryOperator reducer) {
3725	>	public double reduceToDouble(long parallelismThreshold,
3726	>	ToDoubleBiFunction<? super K, ? super V> transformer,
3727	>	double basis,
3728	>	DoubleBinaryOperator reducer) {
3729		if (transformer == null || reducer == null)
3730		throw new NullPointerException();
3731		return new MapReduceMappingsToDoubleTask<K,V>
#	Line 3662 | Line 3811 | public class ConcurrentHashMap<K,V> impl
3811		* for an element, or null if there is no transformation (in
3812		* which case the action is not applied)
3813		* @param action the action
3814	+	* @param <U> the return type of the transformer
3815		* @since 1.8
3816		*/
3817		public <U> void forEachKey(long parallelismThreshold,
#	Line 3685 | Line 3835 | public class ConcurrentHashMap<K,V> impl
3835		* needed for this operation to be executed in parallel
3836		* @param searchFunction a function returning a non-null
3837		* result on success, else null
3838	+	* @param <U> the return type of the search function
3839		* @return a non-null result from applying the given search
3840		* function on each key, or null if none
3841		* @since 1.8
#	Line 3727 | Line 3878 | public class ConcurrentHashMap<K,V> impl
3878		* for an element, or null if there is no transformation (in
3879		* which case it is not combined)
3880		* @param reducer a commutative associative combining function
3881	+	* @param <U> the return type of the transformer
3882		* @return the result of accumulating the given transformation
3883		* of all keys
3884		* @since 1.8
#	Line 3846 | Line 3998 | public class ConcurrentHashMap<K,V> impl
3998		* for an element, or null if there is no transformation (in
3999		* which case the action is not applied)
4000		* @param action the action
4001	+	* @param <U> the return type of the transformer
4002		* @since 1.8
4003		*/
4004		public <U> void forEachValue(long parallelismThreshold,
#	Line 3869 | Line 4022 | public class ConcurrentHashMap<K,V> impl
4022		* needed for this operation to be executed in parallel
4023		* @param searchFunction a function returning a non-null
4024		* result on success, else null
4025	+	* @param <U> the return type of the search function
4026		* @return a non-null result from applying the given search
4027		* function on each value, or null if none
4028		* @since 1.8
#	Line 3910 | Line 4064 | public class ConcurrentHashMap<K,V> impl
4064		* for an element, or null if there is no transformation (in
4065		* which case it is not combined)
4066		* @param reducer a commutative associative combining function
4067	+	* @param <U> the return type of the transformer
4068		* @return the result of accumulating the given transformation
4069		* of all values
4070		* @since 1.8
#	Line 4027 | Line 4182 | public class ConcurrentHashMap<K,V> impl
4182		* for an element, or null if there is no transformation (in
4183		* which case the action is not applied)
4184		* @param action the action
4185	+	* @param <U> the return type of the transformer
4186		* @since 1.8
4187		*/
4188		public <U> void forEachEntry(long parallelismThreshold,
#	Line 4050 | Line 4206 | public class ConcurrentHashMap<K,V> impl
4206		* needed for this operation to be executed in parallel
4207		* @param searchFunction a function returning a non-null
4208		* result on success, else null
4209	+	* @param <U> the return type of the search function
4210		* @return a non-null result from applying the given search
4211		* function on each entry, or null if none
4212		* @since 1.8
#	Line 4091 | Line 4248 | public class ConcurrentHashMap<K,V> impl
4248		* for an element, or null if there is no transformation (in
4249		* which case it is not combined)
4250		* @param reducer a commutative associative combining function
4251	+	* @param <U> the return type of the transformer
4252		* @return the result of accumulating the given transformation
4253		* of all entries
4254		* @since 1.8
#	Line 4213 | Line 4371 | public class ConcurrentHashMap<K,V> impl
4371		// implementations below rely on concrete classes supplying these
4372		// abstract methods
4373		/**
4374	<	* Returns a "weakly consistent" iterator that will never
4375	<	* throw {@link ConcurrentModificationException}, and
4376	<	* guarantees to traverse elements as they existed upon
4377	<	* construction of the iterator, and may (but is not
4378	<	* guaranteed to) reflect any modifications subsequent to
4379	<	* construction.
4374	>	* Returns an iterator over the elements in this collection.
4375	>	*
4376	>	* <p>The returned iterator is
4377	>	* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
4378	>	*
4379	>	* @return an iterator over the elements in this collection
4380		*/
4381		public abstract Iterator<E> iterator();
4382		public abstract boolean contains(Object o);
#	Line 4316 | Line 4474 | public class ConcurrentHashMap<K,V> impl
4474		}
4475
4476		public final boolean removeAll(Collection<?> c) {
4477	+	if (c == null) throw new NullPointerException();
4478		boolean modified = false;
4479		for (Iterator<E> it = iterator(); it.hasNext();) {
4480		if (c.contains(it.next())) {
#	Line 4327 | Line 4486 | public class ConcurrentHashMap<K,V> impl
4486		}
4487
4488		public final boolean retainAll(Collection<?> c) {
4489	+	if (c == null) throw new NullPointerException();
4490		boolean modified = false;
4491		for (Iterator<E> it = iterator(); it.hasNext();) {
4492		if (!c.contains(it.next())) {
#	Line 4621 | Line 4781 | public class ConcurrentHashMap<K,V> impl
4781		* Base class for bulk tasks. Repeats some fields and code from
4782		* class Traverser, because we need to subclass CountedCompleter.
4783		*/
4784	+	@SuppressWarnings("serial")
4785		abstract static class BulkTask<K,V,R> extends CountedCompleter<R> {
4786		Node<K,V>[] tab;        // same as Traverser
4787		Node<K,V> next;
4788	+	TableStack<K,V> stack, spare;
4789		int index;
4790		int baseIndex;
4791		int baseLimit;
#	Line 4652 | Line 4814 | public class ConcurrentHashMap<K,V> impl
4814		if ((e = next) != null)
4815		e = e.next;
4816		for (;;) {
4817	<	Node<K,V>[] t; int i, n; K ek;  // must use locals in checks
4817	>	Node<K,V>[] t; int i, n;
4818		if (e != null)
4819		return next = e;
4820		if (baseIndex >= baseLimit || (t = tab) == null ||
4821		(n = t.length) <= (i = index) || i < 0)
4822		return next = null;
4823	<	if ((e = tabAt(t, index)) != null && e.hash < 0) {
4823	>	if ((e = tabAt(t, i)) != null && e.hash < 0) {
4824		if (e instanceof ForwardingNode) {
4825		tab = ((ForwardingNode<K,V>)e).nextTable;
4826		e = null;
4827	+	pushState(t, i, n);
4828		continue;
4829		}
4830		else if (e instanceof TreeBin)
#	Line 4669 | Line 4832 | public class ConcurrentHashMap<K,V> impl
4832		else
4833		e = null;
4834		}
4835	<	if ((index += baseSize) >= n)
4836	<	index = ++baseIndex;    // visit upper slots if present
4835	>	if (stack != null)
4836	>	recoverState(n);
4837	>	else if ((index = i + baseSize) >= n)
4838	>	index = ++baseIndex;
4839	>	}
4840	>	}
4841	>
4842	>	private void pushState(Node<K,V>[] t, int i, int n) {
4843	>	TableStack<K,V> s = spare;
4844	>	if (s != null)
4845	>	spare = s.next;
4846	>	else
4847	>	s = new TableStack<K,V>();
4848	>	s.tab = t;
4849	>	s.length = n;
4850	>	s.index = i;
4851	>	s.next = stack;
4852	>	stack = s;
4853	>	}
4854	>
4855	>	private void recoverState(int n) {
4856	>	TableStack<K,V> s; int len;
4857	>	while ((s = stack) != null && (index += (len = s.length)) >= n) {
4858	>	n = len;
4859	>	index = s.index;
4860	>	tab = s.tab;
4861	>	s.tab = null;
4862	>	TableStack<K,V> next = s.next;
4863	>	s.next = spare; // save for reuse
4864	>	stack = next;
4865	>	spare = s;
4866		}
4867	+	if (s == null && (index += baseSize) >= n)
4868	+	index = ++baseIndex;
4869		}
4870		}
4871
#	Line 5131 | Line 5325 | public class ConcurrentHashMap<K,V> impl
5325		result = r;
5326		CountedCompleter<?> c;
5327		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5328	<	@SuppressWarnings("unchecked") ReduceKeysTask<K,V>
5328	>	@SuppressWarnings("unchecked")
5329	>	ReduceKeysTask<K,V>
5330		t = (ReduceKeysTask<K,V>)c,
5331		s = t.rights;
5332		while (s != null) {
#	Line 5178 | Line 5373 | public class ConcurrentHashMap<K,V> impl
5373		result = r;
5374		CountedCompleter<?> c;
5375		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5376	<	@SuppressWarnings("unchecked") ReduceValuesTask<K,V>
5376	>	@SuppressWarnings("unchecked")
5377	>	ReduceValuesTask<K,V>
5378		t = (ReduceValuesTask<K,V>)c,
5379		s = t.rights;
5380		while (s != null) {
#	Line 5223 | Line 5419 | public class ConcurrentHashMap<K,V> impl
5419		result = r;
5420		CountedCompleter<?> c;
5421		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5422	<	@SuppressWarnings("unchecked") ReduceEntriesTask<K,V>
5422	>	@SuppressWarnings("unchecked")
5423	>	ReduceEntriesTask<K,V>
5424		t = (ReduceEntriesTask<K,V>)c,
5425		s = t.rights;
5426		while (s != null) {
#	Line 5276 | Line 5473 | public class ConcurrentHashMap<K,V> impl
5473		result = r;
5474		CountedCompleter<?> c;
5475		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5476	<	@SuppressWarnings("unchecked") MapReduceKeysTask<K,V,U>
5476	>	@SuppressWarnings("unchecked")
5477	>	MapReduceKeysTask<K,V,U>
5478		t = (MapReduceKeysTask<K,V,U>)c,
5479		s = t.rights;
5480		while (s != null) {
#	Line 5329 | Line 5527 | public class ConcurrentHashMap<K,V> impl
5527		result = r;
5528		CountedCompleter<?> c;
5529		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5530	<	@SuppressWarnings("unchecked") MapReduceValuesTask<K,V,U>
5530	>	@SuppressWarnings("unchecked")
5531	>	MapReduceValuesTask<K,V,U>
5532		t = (MapReduceValuesTask<K,V,U>)c,
5533		s = t.rights;
5534		while (s != null) {
#	Line 5382 | Line 5581 | public class ConcurrentHashMap<K,V> impl
5581		result = r;
5582		CountedCompleter<?> c;
5583		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5584	<	@SuppressWarnings("unchecked") MapReduceEntriesTask<K,V,U>
5584	>	@SuppressWarnings("unchecked")
5585	>	MapReduceEntriesTask<K,V,U>
5586		t = (MapReduceEntriesTask<K,V,U>)c,
5587		s = t.rights;
5588		while (s != null) {
#	Line 5435 | Line 5635 | public class ConcurrentHashMap<K,V> impl
5635		result = r;
5636		CountedCompleter<?> c;
5637		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5638	<	@SuppressWarnings("unchecked") MapReduceMappingsTask<K,V,U>
5638	>	@SuppressWarnings("unchecked")
5639	>	MapReduceMappingsTask<K,V,U>
5640		t = (MapReduceMappingsTask<K,V,U>)c,
5641		s = t.rights;
5642		while (s != null) {
#	Line 5487 | Line 5688 | public class ConcurrentHashMap<K,V> impl
5688		result = r;
5689		CountedCompleter<?> c;
5690		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5691	<	@SuppressWarnings("unchecked") MapReduceKeysToDoubleTask<K,V>
5691	>	@SuppressWarnings("unchecked")
5692	>	MapReduceKeysToDoubleTask<K,V>
5693		t = (MapReduceKeysToDoubleTask<K,V>)c,
5694		s = t.rights;
5695		while (s != null) {
#	Line 5536 | Line 5738 | public class ConcurrentHashMap<K,V> impl
5738		result = r;
5739		CountedCompleter<?> c;
5740		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5741	<	@SuppressWarnings("unchecked") MapReduceValuesToDoubleTask<K,V>
5741	>	@SuppressWarnings("unchecked")
5742	>	MapReduceValuesToDoubleTask<K,V>
5743		t = (MapReduceValuesToDoubleTask<K,V>)c,
5744		s = t.rights;
5745		while (s != null) {
#	Line 5585 | Line 5788 | public class ConcurrentHashMap<K,V> impl
5788		result = r;
5789		CountedCompleter<?> c;
5790		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5791	<	@SuppressWarnings("unchecked") MapReduceEntriesToDoubleTask<K,V>
5791	>	@SuppressWarnings("unchecked")
5792	>	MapReduceEntriesToDoubleTask<K,V>
5793		t = (MapReduceEntriesToDoubleTask<K,V>)c,
5794		s = t.rights;
5795		while (s != null) {
#	Line 5634 | Line 5838 | public class ConcurrentHashMap<K,V> impl
5838		result = r;
5839		CountedCompleter<?> c;
5840		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5841	<	@SuppressWarnings("unchecked") MapReduceMappingsToDoubleTask<K,V>
5841	>	@SuppressWarnings("unchecked")
5842	>	MapReduceMappingsToDoubleTask<K,V>
5843		t = (MapReduceMappingsToDoubleTask<K,V>)c,
5844		s = t.rights;
5845		while (s != null) {
#	Line 5683 | Line 5888 | public class ConcurrentHashMap<K,V> impl
5888		result = r;
5889		CountedCompleter<?> c;
5890		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5891	<	@SuppressWarnings("unchecked") MapReduceKeysToLongTask<K,V>
5891	>	@SuppressWarnings("unchecked")
5892	>	MapReduceKeysToLongTask<K,V>
5893		t = (MapReduceKeysToLongTask<K,V>)c,
5894		s = t.rights;
5895		while (s != null) {
#	Line 5732 | Line 5938 | public class ConcurrentHashMap<K,V> impl
5938		result = r;
5939		CountedCompleter<?> c;
5940		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5941	<	@SuppressWarnings("unchecked") MapReduceValuesToLongTask<K,V>
5941	>	@SuppressWarnings("unchecked")
5942	>	MapReduceValuesToLongTask<K,V>
5943		t = (MapReduceValuesToLongTask<K,V>)c,
5944		s = t.rights;
5945		while (s != null) {
#	Line 5781 | Line 5988 | public class ConcurrentHashMap<K,V> impl
5988		result = r;
5989		CountedCompleter<?> c;
5990		for (c = firstComplete(); c != null; c = c.nextComplete()) {
5991	<	@SuppressWarnings("unchecked") MapReduceEntriesToLongTask<K,V>
5991	>	@SuppressWarnings("unchecked")
5992	>	MapReduceEntriesToLongTask<K,V>
5993		t = (MapReduceEntriesToLongTask<K,V>)c,
5994		s = t.rights;
5995		while (s != null) {
#	Line 5830 | Line 6038 | public class ConcurrentHashMap<K,V> impl
6038		result = r;
6039		CountedCompleter<?> c;
6040		for (c = firstComplete(); c != null; c = c.nextComplete()) {
6041	<	@SuppressWarnings("unchecked") MapReduceMappingsToLongTask<K,V>
6041	>	@SuppressWarnings("unchecked")
6042	>	MapReduceMappingsToLongTask<K,V>
6043		t = (MapReduceMappingsToLongTask<K,V>)c,
6044		s = t.rights;
6045		while (s != null) {
#	Line 5879 | Line 6088 | public class ConcurrentHashMap<K,V> impl
6088		result = r;
6089		CountedCompleter<?> c;
6090		for (c = firstComplete(); c != null; c = c.nextComplete()) {
6091	<	@SuppressWarnings("unchecked") MapReduceKeysToIntTask<K,V>
6091	>	@SuppressWarnings("unchecked")
6092	>	MapReduceKeysToIntTask<K,V>
6093		t = (MapReduceKeysToIntTask<K,V>)c,
6094		s = t.rights;
6095		while (s != null) {
#	Line 5928 | Line 6138 | public class ConcurrentHashMap<K,V> impl
6138		result = r;
6139		CountedCompleter<?> c;
6140		for (c = firstComplete(); c != null; c = c.nextComplete()) {
6141	<	@SuppressWarnings("unchecked") MapReduceValuesToIntTask<K,V>
6141	>	@SuppressWarnings("unchecked")
6142	>	MapReduceValuesToIntTask<K,V>
6143		t = (MapReduceValuesToIntTask<K,V>)c,
6144		s = t.rights;
6145		while (s != null) {
#	Line 5977 | Line 6188 | public class ConcurrentHashMap<K,V> impl
6188		result = r;
6189		CountedCompleter<?> c;
6190		for (c = firstComplete(); c != null; c = c.nextComplete()) {
6191	<	@SuppressWarnings("unchecked") MapReduceEntriesToIntTask<K,V>
6191	>	@SuppressWarnings("unchecked")
6192	>	MapReduceEntriesToIntTask<K,V>
6193		t = (MapReduceEntriesToIntTask<K,V>)c,
6194		s = t.rights;
6195		while (s != null) {
#	Line 6026 | Line 6238 | public class ConcurrentHashMap<K,V> impl
6238		result = r;
6239		CountedCompleter<?> c;
6240		for (c = firstComplete(); c != null; c = c.nextComplete()) {
6241	<	@SuppressWarnings("unchecked") MapReduceMappingsToIntTask<K,V>
6241	>	@SuppressWarnings("unchecked")
6242	>	MapReduceMappingsToIntTask<K,V>
6243		t = (MapReduceMappingsToIntTask<K,V>)c,
6244		s = t.rights;
6245		while (s != null) {
#	Line 6042 | Line 6255 | public class ConcurrentHashMap<K,V> impl
6255		private static final sun.misc.Unsafe U;
6256		private static final long SIZECTL;
6257		private static final long TRANSFERINDEX;
6045	–	private static final long TRANSFERORIGIN;
6258		private static final long BASECOUNT;
6259		private static final long CELLSBUSY;
6260		private static final long CELLVALUE;
#	Line 6057 | Line 6269 | public class ConcurrentHashMap<K,V> impl
6269		(k.getDeclaredField("sizeCtl"));
6270		TRANSFERINDEX = U.objectFieldOffset
6271		(k.getDeclaredField("transferIndex"));
6060	–	TRANSFERORIGIN = U.objectFieldOffset
6061	–	(k.getDeclaredField("transferOrigin"));
6272		BASECOUNT = U.objectFieldOffset
6273		(k.getDeclaredField("baseCount"));
6274		CELLSBUSY = U.objectFieldOffset
#	Line 6070 | Line 6280 | public class ConcurrentHashMap<K,V> impl
6280		ABASE = U.arrayBaseOffset(ak);
6281		int scale = U.arrayIndexScale(ak);
6282		if ((scale & (scale - 1)) != 0)
6283	<	throw new Error("data type scale not a power of two");
6283	>	throw new Error("array index scale not a power of two");
6284		ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
6285	<	} catch (Exception e) {
6285	>	} catch (ReflectiveOperationException e) {
6286		throw new Error(e);
6287		}
6288		}

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