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Comparing jsr166/src/jsr166e/ConcurrentHashMapV8.java (file contents):
Revision 1.24 by dl, Thu Sep 15 14:25:46 2011 UTC vs.
Revision 1.38 by dl, Wed Jun 6 15:41:23 2012 UTC

#	Line 4 | Line 4
4		* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7	+	// Snapshot Tue Jun  5 14:56:09 2012  Doug Lea  (dl at altair)
8	+
9		package jsr166e;
10		import jsr166e.LongAdder;
11		import java.util.Arrays;
#	Line 20 | Line 22 | import java.util.Enumeration;
22		import java.util.ConcurrentModificationException;
23		import java.util.NoSuchElementException;
24		import java.util.concurrent.ConcurrentMap;
25	+	import java.util.concurrent.ThreadLocalRandom;
26		import java.util.concurrent.locks.LockSupport;
27	+	import java.util.concurrent.locks.AbstractQueuedSynchronizer;
28		import java.io.Serializable;
29
30		/**
#	Line 71 | Line 75 | import java.io.Serializable;
75		* versions of this class, constructors may optionally specify an
76		* expected {@code concurrencyLevel} as an additional hint for
77		* internal sizing.  Note that using many keys with exactly the same
78	<	* {@code hashCode{}} is a sure way to slow down performance of any
78	>	* {@code hashCode()} is a sure way to slow down performance of any
79		* hash table.
80		*
81		* <p>This class and its views and iterators implement all of the
#	Line 98 | Line 102 | public class ConcurrentHashMapV8<K, V>
102		private static final long serialVersionUID = 7249069246763182397L;
103
104		/**
105	<	* A function computing a mapping from the given key to a value,
106	<	* or {@code null} if there is no mapping. This is a place-holder
103	<	* for an upcoming JDK8 interface.
105	>	* A function computing a mapping from the given key to a value.
106	>	* This is a place-holder for an upcoming JDK8 interface.
107		*/
108		public static interface MappingFunction<K, V> {
109		/**
110	<	* Returns a value for the given key, or null if there is no
108	<	* mapping. If this function throws an (unchecked) exception,
109	<	* the exception is rethrown to its caller, and no mapping is
110	<	* recorded.  Because this function is invoked within
111	<	* atomicity control, the computation should be short and
112	<	* simple. The most common usage is to construct a new object
113	<	* serving as an initial mapped value.
110	>	* Returns a non-null value for the given key.
111		*
112		* @param key the (non-null) key
113	<	* @return a value, or null if none
113	>	* @return a non-null value
114		*/
115		V map(K key);
116		}
117
118	+	/**
119	+	* A function computing a new mapping given a key and its current
120	+	* mapped value (or {@code null} if there is no current
121	+	* mapping). This is a place-holder for an upcoming JDK8
122	+	* interface.
123	+	*/
124	+	public static interface RemappingFunction<K, V> {
125	+	/**
126	+	* Returns a new value given a key and its current value.
127	+	*
128	+	* @param key the (non-null) key
129	+	* @param value the current value, or null if there is no mapping
130	+	* @return a non-null value
131	+	*/
132	+	V remap(K key, V value);
133	+	}
134	+
135		/*
136		* Overview:
137		*
#	Line 134 | Line 148 | public class ConcurrentHashMapV8<K, V>
148		* work off Object types. And similarly, so do the internal
149		* methods of auxiliary iterator and view classes.  All public
150		* generic typed methods relay in/out of these internal methods,
151	<	* supplying null-checks and casts as needed.
151	>	* supplying null-checks and casts as needed. This also allows
152	>	* many of the public methods to be factored into a smaller number
153	>	* of internal methods (although sadly not so for the five
154	>	* variants of put-related operations). The validation-based
155	>	* approach explained below leads to a lot of code sprawl because
156	>	* retry-control precludes factoring into smaller methods.
157		*
158		* The table is lazily initialized to a power-of-two size upon the
159	<	* first insertion.  Each bin in the table contains a list of
160	<	* Nodes (most often, zero or one Node).  Table accesses require
161	<	* volatile/atomic reads, writes, and CASes.  Because there is no
162	<	* other way to arrange this without adding further indirections,
163	<	* we use intrinsics (sun.misc.Unsafe) operations.  The lists of
164	<	* nodes within bins are always accurately traversable under
165	<	* volatile reads, so long as lookups check hash code and
166	<	* non-nullness of value before checking key equality.
159	>	* first insertion.  Each bin in the table normally contains a
160	>	* list of Nodes (most often, the list has only zero or one Node).
161	>	* Table accesses require volatile/atomic reads, writes, and
162	>	* CASes.  Because there is no other way to arrange this without
163	>	* adding further indirections, we use intrinsics
164	>	* (sun.misc.Unsafe) operations.  The lists of nodes within bins
165	>	* are always accurately traversable under volatile reads, so long
166	>	* as lookups check hash code and non-nullness of value before
167	>	* checking key equality.
168		*
169		* We use the top two bits of Node hash fields for control
170		* purposes -- they are available anyway because of addressing
171		* constraints.  As explained further below, these top bits are
172	<	* usd as follows:
172	>	* used as follows:
173		*  00 - Normal
174		*  01 - Locked
175		*  11 - Locked and may have a thread waiting for lock
176		*  10 - Node is a forwarding node
177		*
178		* The lower 30 bits of each Node's hash field contain a
179	<	* transformation (for better randomization -- method "spread") of
180	<	* the key's hash code, except for forwarding nodes, for which the
181	<	* lower bits are zero (and so always have hash field == "MOVED").
179	>	* transformation of the key's hash code, except for forwarding
180	>	* nodes, for which the lower bits are zero (and so always have
181	>	* hash field == MOVED).
182		*
183	<	* Insertion (via put or putIfAbsent) of the first node in an
183	>	* Insertion (via put or its variants) of the first node in an
184		* empty bin is performed by just CASing it to the bin.  This is
185	<	* by far the most common case for put operations.  Other update
186	<	* operations (insert, delete, and replace) require locks.  We do
187	<	* not want to waste the space required to associate a distinct
188	<	* lock object with each bin, so instead use the first node of a
189	<	* bin list itself as a lock. Blocking support for these locks
190	<	* relies on the builtin "synchronized" monitors.  However, we
191	<	* also need a tryLock construction, so we overlay these by using
192	<	* bits of the Node hash field for lock control (see above), and
193	<	* so normally use builtin monitors only for blocking and
194	<	* signalling using wait/notifyAll constructions. See
195	<	* Node.tryAwaitLock.
185	>	* by far the most common case for put operations under most
186	>	* key/hash distributions.  Other update operations (insert,
187	>	* delete, and replace) require locks.  We do not want to waste
188	>	* the space required to associate a distinct lock object with
189	>	* each bin, so instead use the first node of a bin list itself as
190	>	* a lock. Blocking support for these locks relies on the builtin
191	>	* "synchronized" monitors.  However, we also need a tryLock
192	>	* construction, so we overlay these by using bits of the Node
193	>	* hash field for lock control (see above), and so normally use
194	>	* builtin monitors only for blocking and signalling using
195	>	* wait/notifyAll constructions. See Node.tryAwaitLock.
196		*
197		* Using the first node of a list as a lock does not by itself
198		* suffice though: When a node is locked, any update must first
199		* validate that it is still the first node after locking it, and
200		* retry if not. Because new nodes are always appended to lists,
201		* once a node is first in a bin, it remains first until deleted
202	<	* or the bin becomes invalidated.  However, operations that only
203	<	* conditionally update may inspect nodes until the point of
204	<	* update. This is a converse of sorts to the lazy locking
205	<	* technique described by Herlihy & Shavit.
202	>	* or the bin becomes invalidated (upon resizing).  However,
203	>	* operations that only conditionally update may inspect nodes
204	>	* until the point of update. This is a converse of sorts to the
205	>	* lazy locking technique described by Herlihy & Shavit.
206		*
207		* The main disadvantage of per-bin locks is that other update
208		* operations on other nodes in a bin list protected by the same
209		* lock can stall, for example when user equals() or mapping
210	<	* functions take a long time.  However, statistically, this is
211	<	* not a common enough problem to outweigh the time/space overhead
212	<	* of alternatives: Under random hash codes, the frequency of
193	<	* nodes in bins follows a Poisson distribution
210	>	* functions take a long time.  However, statistically, under
211	>	* random hash codes, this is not a common problem.  Ideally, the
212	>	* frequency of nodes in bins follows a Poisson distribution
213		* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
214		* parameter of about 0.5 on average, given the resizing threshold
215		* of 0.75, although with a large variance because of resizing
216		* granularity. Ignoring variance, the expected occurrences of
217		* list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The
218	<	* first few values are:
218	>	* first values are:
219		*
220	<	* 0:    0.607
221	<	* 1:    0.303
222	<	* 2:    0.076
223	<	* 3:    0.012
224	<	* more: 0.002
220	>	* 0:    0.60653066
221	>	* 1:    0.30326533
222	>	* 2:    0.07581633
223	>	* 3:    0.01263606
224	>	* 4:    0.00157952
225	>	* 5:    0.00015795
226	>	* 6:    0.00001316
227	>	* 7:    0.00000094
228	>	* 8:    0.00000006
229	>	* more: less than 1 in ten million
230		*
231		* Lock contention probability for two threads accessing distinct
232	<	* elements is roughly 1 / (8 * #elements).  Function "spread"
209	<	* performs hashCode randomization that improves the likelihood
210	<	* that these assumptions hold unless users define exactly the
211	<	* same value for too many hashCodes.
232	>	* elements is roughly 1 / (8 * #elements) under random hashes.
233		*
234	<	* The table is resized when occupancy exceeds an occupancy
234	>	* Actual hash code distributions encountered in practice
235	>	* sometimes deviate significantly from uniform randomness.  This
236	>	* includes the case when N > (1<<30), so some keys MUST collide.
237	>	* Similarly for dumb or hostile usages in which multiple keys are
238	>	* designed to have identical hash codes. Also, although we guard
239	>	* against the worst effects of this (see method spread), sets of
240	>	* hashes may differ only in bits that do not impact their bin
241	>	* index for a given power-of-two mask.  So we use a secondary
242	>	* strategy that applies when the number of nodes in a bin exceeds
243	>	* a threshold, and at least one of the keys implements
244	>	* Comparable.  These TreeBins use a balanced tree to hold nodes
245	>	* (a specialized form of red-black trees), bounding search time
246	>	* to O(log N).  Each search step in a TreeBin is around twice as
247	>	* slow as in a regular list, but given that N cannot exceed
248	>	* (1<<64) (before running out of addresses) this bounds search
249	>	* steps, lock hold times, etc, to reasonable constants (roughly
250	>	* 100 nodes inspected per operation worst case) so long as keys
251	>	* are Comparable (which is very common -- String, Long, etc).
252	>	* TreeBin nodes (TreeNodes) also maintain the same "next"
253	>	* traversal pointers as regular nodes, so can be traversed in
254	>	* iterators in the same way.
255	>	*
256	>	* The table is resized when occupancy exceeds a percentage
257		* threshold (nominally, 0.75, but see below).  Only a single
258		* thread performs the resize (using field "sizeCtl", to arrange
259		* exclusion), but the table otherwise remains usable for reads
#	Line 231 | Line 274 | public class ConcurrentHashMapV8<K, V>
274		*
275		* Each bin transfer requires its bin lock. However, unlike other
276		* cases, a transfer can skip a bin if it fails to acquire its
277	<	* lock, and revisit it later. Method rebuild maintains a buffer
278	<	* of TRANSFER_BUFFER_SIZE bins that have been skipped because of
279	<	* failure to acquire a lock, and blocks only if none are
280	<	* available (i.e., only very rarely).  The transfer operation
281	<	* must also ensure that all accessible bins in both the old and
282	<	* new table are usable by any traversal.  When there are no lock
283	<	* acquisition failures, this is arranged simply by proceeding
284	<	* from the last bin (table.length - 1) up towards the first.
285	<	* Upon seeing a forwarding node, traversals (see class
286	<	* InternalIterator) arrange to move to the new table without
287	<	* revisiting nodes.  However, when any node is skipped during a
288	<	* transfer, all earlier table bins may have become visible, so
289	<	* are initialized with a reverse-forwarding node back to the old
290	<	* table until the new ones are established. (This sometimes
291	<	* requires transiently locking a forwarding node, which is
292	<	* possible under the above encoding.) These more expensive
277	>	* lock, and revisit it later (unless it is a TreeBin). Method
278	>	* rebuild maintains a buffer of TRANSFER_BUFFER_SIZE bins that
279	>	* have been skipped because of failure to acquire a lock, and
280	>	* blocks only if none are available (i.e., only very rarely).
281	>	* The transfer operation must also ensure that all accessible
282	>	* bins in both the old and new table are usable by any traversal.
283	>	* When there are no lock acquisition failures, this is arranged
284	>	* simply by proceeding from the last bin (table.length - 1) up
285	>	* towards the first.  Upon seeing a forwarding node, traversals
286	>	* (see class InternalIterator) arrange to move to the new table
287	>	* without revisiting nodes.  However, when any node is skipped
288	>	* during a transfer, all earlier table bins may have become
289	>	* visible, so are initialized with a reverse-forwarding node back
290	>	* to the old table until the new ones are established. (This
291	>	* sometimes requires transiently locking a forwarding node, which
292	>	* is possible under the above encoding.) These more expensive
293		* mechanics trigger only when necessary.
294		*
295		* The traversal scheme also applies to partial traversals of
#	Line 266 | Line 309 | public class ConcurrentHashMapV8<K, V>
309		* The element count is maintained using a LongAdder, which avoids
310		* contention on updates but can encounter cache thrashing if read
311		* too frequently during concurrent access. To avoid reading so
312	<	* often, resizing is normally attempted only upon adding to a bin
313	<	* already holding two or more nodes. Under uniform hash
314	<	* distributions, the probability of this occurring at threshold
315	<	* is around 13%, meaning that only about 1 in 8 puts check
316	<	* threshold (and after resizing, many fewer do so). But this
317	<	* approximation has high variance for small table sizes, so we
318	<	* check on any collision for sizes <= 64.
312	>	* often, resizing is attempted either when a bin lock is
313	>	* contended, or upon adding to a bin already holding two or more
314	>	* nodes (checked before adding in the xIfAbsent methods, after
315	>	* adding in others). Under uniform hash distributions, the
316	>	* probability of this occurring at threshold is around 13%,
317	>	* meaning that only about 1 in 8 puts check threshold (and after
318	>	* resizing, many fewer do so). But this approximation has high
319	>	* variance for small table sizes, so we check on any collision
320	>	* for sizes <= 64. The bulk putAll operation further reduces
321	>	* contention by only committing count updates upon these size
322	>	* checks.
323		*
324		* Maintaining API and serialization compatibility with previous
325		* versions of this class introduces several oddities. Mainly: We
#	Line 329 | Line 376 | public class ConcurrentHashMapV8<K, V>
376		*/
377		private static final int TRANSFER_BUFFER_SIZE = 32;
378
379	+	/**
380	+	* The bin count threshold for using a tree rather than list for a
381	+	* bin.  The value reflects the approximate break-even point for
382	+	* using tree-based operations.
383	+	*/
384	+	private static final int TREE_THRESHOLD = 8;
385	+
386		/*
387		* Encodings for special uses of Node hash fields. See above for
388		* explanation.
389		*/
390	<	static final int MOVED     = 0x80000000; // hash field for fowarding nodes
390	>	static final int MOVED     = 0x80000000; // hash field for forwarding nodes
391		static final int LOCKED    = 0x40000000; // set/tested only as a bit
392		static final int WAITING   = 0xc0000000; // both bits set/tested together
393		static final int HASH_BITS = 0x3fffffff; // usable bits of normal node hash
#	Line 368 | Line 422 | public class ConcurrentHashMapV8<K, V>
422		/** For serialization compatibility. Null unless serialized; see below */
423		private Segment<K,V>[] segments;
424
425	+	/* ---------------- Table element access -------------- */
426	+
427	+	/*
428	+	* Volatile access methods are used for table elements as well as
429	+	* elements of in-progress next table while resizing.  Uses are
430	+	* null checked by callers, and implicitly bounds-checked, relying
431	+	* on the invariants that tab arrays have non-zero size, and all
432	+	* indices are masked with (tab.length - 1) which is never
433	+	* negative and always less than length. Note that, to be correct
434	+	* wrt arbitrary concurrency errors by users, bounds checks must
435	+	* operate on local variables, which accounts for some odd-looking
436	+	* inline assignments below.
437	+	*/
438	+
439	+	static final Node tabAt(Node[] tab, int i) { // used by InternalIterator
440	+	return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE);
441	+	}
442	+
443	+	private static final boolean casTabAt(Node[] tab, int i, Node c, Node v) {
444	+	return UNSAFE.compareAndSwapObject(tab, ((long)i<<ASHIFT)+ABASE, c, v);
445	+	}
446	+
447	+	private static final void setTabAt(Node[] tab, int i, Node v) {
448	+	UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v);
449	+	}
450	+
451		/* ---------------- Nodes -------------- */
452
453		/**
454		* Key-value entry. Note that this is never exported out as a
455		* user-visible Map.Entry (see WriteThroughEntry and SnapshotEntry
456	<	* below). Nodes with a negative hash field are special, and do
456	>	* below). Nodes with a hash field of MOVED are special, and do
457		* not contain user keys or values.  Otherwise, keys are never
458		* null, and null val fields indicate that a node is in the
459		* process of being deleted or created. For purposes of read-only
460		* access, a key may be read before a val, but can only be used
461		* after checking val to be non-null.
462		*/
463	<	static final class Node {
463	>	static class Node {
464		volatile int hash;
465		final Object key;
466		volatile Object val;
#	Line 417 | Line 497 | public class ConcurrentHashMapV8<K, V>
497		*/
498		final void tryAwaitLock(Node[] tab, int i) {
499		if (tab != null && i >= 0 && i < tab.length) { // bounds check
500	+	int r = ThreadLocalRandom.current().nextInt(); // randomize spins
501		int spins = MAX_SPINS, h;
502		while (tabAt(tab, i) == this && ((h = hash) & LOCKED) != 0) {
503		if (spins >= 0) {
504	<	if (--spins == MAX_SPINS >>> 1)
505	<	Thread.yield();  // heuristically yield mid-way
504	>	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
505	>	if (r >= 0 && --spins == 0)
506	>	Thread.yield();  // yield before block
507		}
508		else if (casHash(h, h | WAITING)) {
509	<	synchronized(this) {
509	>	synchronized (this) {
510		if (tabAt(tab, i) == this &&
511		(hash & WAITING) == WAITING) {
512		try {
#	Line 458 | Line 540 | public class ConcurrentHashMapV8<K, V>
540		}
541		}
542
543	<	/* ---------------- Table element access -------------- */
543	>	/* ---------------- TreeBins -------------- */
544
545	<	/*
546	<	* Volatile access methods are used for table elements as well as
465	<	* elements of in-progress next table while resizing.  Uses are
466	<	* null checked by callers, and implicitly bounds-checked, relying
467	<	* on the invariants that tab arrays have non-zero size, and all
468	<	* indices are masked with (tab.length - 1) which is never
469	<	* negative and always less than length. Note that, to be correct
470	<	* wrt arbitrary concurrency errors by users, bounds checks must
471	<	* operate on local variables, which accounts for some odd-looking
472	<	* inline assignments below.
545	>	/**
546	>	* Nodes for use in TreeBins
547		*/
548	<
549	<	static final Node tabAt(Node[] tab, int i) { // used by InternalIterator
550	<	return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE);
548	>	static final class TreeNode extends Node {
549	>	TreeNode parent;  // red-black tree links
550	>	TreeNode left;
551	>	TreeNode right;
552	>	TreeNode prev;    // needed to unlink next upon deletion
553	>	boolean red;
554	>
555	>	TreeNode(int hash, Object key, Object val, Node next, TreeNode parent) {
556	>	super(hash, key, val, next);
557	>	this.parent = parent;
558	>	}
559		}
560
561	<	private static final boolean casTabAt(Node[] tab, int i, Node c, Node v) {
562	<	return UNSAFE.compareAndSwapObject(tab, ((long)i<<ASHIFT)+ABASE, c, v);
563	<	}
561	>	/**
562	>	* A specialized form of red-black tree for use in bins
563	>	* whose size exceeds a threshold.
564	>	*
565	>	* TreeBins use a special form of comparison for search and
566	>	* related operations (which is the main reason we cannot use
567	>	* existing collections such as TreeMaps). TreeBins contain
568	>	* Comparable elements, but may contain others, as well as
569	>	* elements that are Comparable but not necessarily Comparable<T>
570	>	* for the same T, so we cannot invoke compareTo among them. To
571	>	* handle this, the tree is ordered primarily by hash value, then
572	>	* by getClass().getName() order, and then by Comparator order
573	>	* among elements of the same class.  On lookup at a node, if
574	>	* non-Comparable, both left and right children may need to be
575	>	* searched in the case of tied hash values. (This corresponds to
576	>	* the full list search that would be necessary if all elements
577	>	* were non-Comparable and had tied hashes.)
578	>	*
579	>	* TreeBins also maintain a separate locking discipline than
580	>	* regular bins. Because they are forwarded via special MOVED
581	>	* nodes at bin heads (which can never change once established),
582	>	* we cannot use use those nodes as locks. Instead, TreeBin
583	>	* extends AbstractQueuedSynchronizer to support a simple form of
584	>	* read-write lock. For update operations and table validation,
585	>	* the exclusive form of lock behaves in the same way as bin-head
586	>	* locks. However, lookups use shared read-lock mechanics to allow
587	>	* multiple readers in the absence of writers.  Additionally,
588	>	* these lookups do not ever block: While the lock is not
589	>	* available, they proceed along the slow traversal path (via
590	>	* next-pointers) until the lock becomes available or the list is
591	>	* exhausted, whichever comes first. (These cases are not fast,
592	>	* but maximize aggregate expected throughput.)  The AQS mechanics
593	>	* for doing this are straightforward.  The lock state is held as
594	>	* AQS getState().  Read counts are negative; the write count (1)
595	>	* is positive.  There are no signalling preferences among readers
596	>	* and writers. Since we don't need to export full Lock API, we
597	>	* just override the minimal AQS methods and use them directly.
598	>	*/
599	>	static final class TreeBin extends AbstractQueuedSynchronizer {
600	>	private static final long serialVersionUID = 2249069246763182397L;
601	>	TreeNode root;  // root of tree
602	>	TreeNode first; // head of next-pointer list
603
604	<	private static final void setTabAt(Node[] tab, int i, Node v) {
605	<	UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v);
604	>	/* AQS overrides */
605	>	public final boolean isHeldExclusively() { return getState() > 0; }
606	>	public final boolean tryAcquire(int ignore) {
607	>	if (compareAndSetState(0, 1)) {
608	>	setExclusiveOwnerThread(Thread.currentThread());
609	>	return true;
610	>	}
611	>	return false;
612	>	}
613	>	public final boolean tryRelease(int ignore) {
614	>	setExclusiveOwnerThread(null);
615	>	setState(0);
616	>	return true;
617	>	}
618	>	public final int tryAcquireShared(int ignore) {
619	>	for (int c;;) {
620	>	if ((c = getState()) > 0)
621	>	return -1;
622	>	if (compareAndSetState(c, c -1))
623	>	return 1;
624	>	}
625	>	}
626	>	public final boolean tryReleaseShared(int ignore) {
627	>	int c;
628	>	do {} while (!compareAndSetState(c = getState(), c + 1));
629	>	return c == -1;
630	>	}
631	>
632	>	/**
633	>	* Return the TreeNode (or null if not found) for the given key
634	>	* starting at given root.
635	>	*/
636	>	@SuppressWarnings("unchecked") // suppress Comparable cast warning
637	>	final TreeNode getTreeNode(int h, Object k, TreeNode p) {
638	>	Class<?> c = k.getClass();
639	>	while (p != null) {
640	>	int dir, ph;  Object pk; Class<?> pc; TreeNode r;
641	>	if (h < (ph = p.hash))
642	>	dir = -1;
643	>	else if (h > ph)
644	>	dir = 1;
645	>	else if ((pk = p.key) == k || k.equals(pk))
646	>	return p;
647	>	else if (c != (pc = pk.getClass()))
648	>	dir = c.getName().compareTo(pc.getName());
649	>	else if (k instanceof Comparable)
650	>	dir = ((Comparable)k).compareTo((Comparable)pk);
651	>	else
652	>	dir = 0;
653	>	TreeNode pr = p.right;
654	>	if (dir > 0)
655	>	p = pr;
656	>	else if (dir == 0 && pr != null && h >= pr.hash &&
657	>	(r = getTreeNode(h, k, pr)) != null)
658	>	return r;
659	>	else
660	>	p = p.left;
661	>	}
662	>	return null;
663	>	}
664	>
665	>	/**
666	>	* Wrapper for getTreeNode used by CHM.get. Tries to obtain
667	>	* read-lock to call getTreeNode, but during failure to get
668	>	* lock, searches along next links.
669	>	*/
670	>	final Object getValue(int h, Object k) {
671	>	Node r = null;
672	>	int c = getState(); // Must read lock state first
673	>	for (Node e = first; e != null; e = e.next) {
674	>	if (c <= 0 && compareAndSetState(c, c - 1)) {
675	>	try {
676	>	r = getTreeNode(h, k, root);
677	>	} finally {
678	>	releaseShared(0);
679	>	}
680	>	break;
681	>	}
682	>	else if ((e.hash & HASH_BITS) == h && k.equals(e.key)) {
683	>	r = e;
684	>	break;
685	>	}
686	>	else
687	>	c = getState();
688	>	}
689	>	return r == null ? null : r.val;
690	>	}
691	>
692	>	/**
693	>	* Find or add a node
694	>	* @return null if added
695	>	*/
696	>	@SuppressWarnings("unchecked") // suppress Comparable cast warning
697	>	final TreeNode putTreeNode(int h, Object k, Object v) {
698	>	Class<?> c = k.getClass();
699	>	TreeNode p = root;
700	>	int dir = 0;
701	>	if (p != null) {
702	>	for (;;) {
703	>	int ph;  Object pk; Class<?> pc; TreeNode r;
704	>	if (h < (ph = p.hash))
705	>	dir = -1;
706	>	else if (h > ph)
707	>	dir = 1;
708	>	else if ((pk = p.key) == k || k.equals(pk))
709	>	return p;
710	>	else if (c != (pc = (pk = p.key).getClass()))
711	>	dir = c.getName().compareTo(pc.getName());
712	>	else if (k instanceof Comparable)
713	>	dir = ((Comparable)k).compareTo((Comparable)pk);
714	>	else
715	>	dir = 0;
716	>	TreeNode pr = p.right, pl;
717	>	if (dir > 0) {
718	>	if (pr == null)
719	>	break;
720	>	p = pr;
721	>	}
722	>	else if (dir == 0 && pr != null && h >= pr.hash &&
723	>	(r = getTreeNode(h, k, pr)) != null)
724	>	return r;
725	>	else if ((pl = p.left) == null)
726	>	break;
727	>	else
728	>	p = pl;
729	>	}
730	>	}
731	>	TreeNode f = first;
732	>	TreeNode r = first = new TreeNode(h, k, v, f, p);
733	>	if (p == null)
734	>	root = r;
735	>	else {
736	>	if (dir <= 0)
737	>	p.left = r;
738	>	else
739	>	p.right = r;
740	>	if (f != null)
741	>	f.prev = r;
742	>	fixAfterInsertion(r);
743	>	}
744	>	return null;
745	>	}
746	>
747	>	/**
748	>	* Removes the given node, that must be present before this
749	>	* call.  This is messier than typical red-black deletion code
750	>	* because we cannot swap the contents of an interior node
751	>	* with a leaf successor that is pinned by "next" pointers
752	>	* that are accessible independently of lock. So instead we
753	>	* swap the tree linkages.
754	>	*/
755	>	final void deleteTreeNode(TreeNode p) {
756	>	TreeNode next = (TreeNode)p.next; // unlink traversal pointers
757	>	TreeNode pred = p.prev;
758	>	if (pred == null)
759	>	first = next;
760	>	else
761	>	pred.next = next;
762	>	if (next != null)
763	>	next.prev = pred;
764	>	TreeNode replacement;
765	>	TreeNode pl = p.left;
766	>	TreeNode pr = p.right;
767	>	if (pl != null && pr != null) {
768	>	TreeNode s = pr;
769	>	while (s.left != null) // find successor
770	>	s = s.left;
771	>	boolean c = s.red; s.red = p.red; p.red = c; // swap colors
772	>	TreeNode sr = s.right;
773	>	TreeNode pp = p.parent;
774	>	if (s == pr) { // p was s's direct parent
775	>	p.parent = s;
776	>	s.right = p;
777	>	}
778	>	else {
779	>	TreeNode sp = s.parent;
780	>	if ((p.parent = sp) != null) {
781	>	if (s == sp.left)
782	>	sp.left = p;
783	>	else
784	>	sp.right = p;
785	>	}
786	>	if ((s.right = pr) != null)
787	>	pr.parent = s;
788	>	}
789	>	p.left = null;
790	>	if ((p.right = sr) != null)
791	>	sr.parent = p;
792	>	if ((s.left = pl) != null)
793	>	pl.parent = s;
794	>	if ((s.parent = pp) == null)
795	>	root = s;
796	>	else if (p == pp.left)
797	>	pp.left = s;
798	>	else
799	>	pp.right = s;
800	>	replacement = sr;
801	>	}
802	>	else
803	>	replacement = (pl != null) ? pl : pr;
804	>	TreeNode pp = p.parent;
805	>	if (replacement == null) {
806	>	if (pp == null) {
807	>	root = null;
808	>	return;
809	>	}
810	>	replacement = p;
811	>	}
812	>	else {
813	>	replacement.parent = pp;
814	>	if (pp == null)
815	>	root = replacement;
816	>	else if (p == pp.left)
817	>	pp.left = replacement;
818	>	else
819	>	pp.right = replacement;
820	>	p.left = p.right = p.parent = null;
821	>	}
822	>	if (!p.red)
823	>	fixAfterDeletion(replacement);
824	>	if (p == replacement && (pp = p.parent) != null) {
825	>	if (p == pp.left) // detach pointers
826	>	pp.left = null;
827	>	else if (p == pp.right)
828	>	pp.right = null;
829	>	p.parent = null;
830	>	}
831	>	}
832	>
833	>	// CLR code updated from pre-jdk-collections version at
834	>	// http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java
835	>
836	>	/** From CLR */
837	>	private void rotateLeft(TreeNode p) {
838	>	if (p != null) {
839	>	TreeNode r = p.right, pp, rl;
840	>	if ((rl = p.right = r.left) != null)
841	>	rl.parent = p;
842	>	if ((pp = r.parent = p.parent) == null)
843	>	root = r;
844	>	else if (pp.left == p)
845	>	pp.left = r;
846	>	else
847	>	pp.right = r;
848	>	r.left = p;
849	>	p.parent = r;
850	>	}
851	>	}
852	>
853	>	/** From CLR */
854	>	private void rotateRight(TreeNode p) {
855	>	if (p != null) {
856	>	TreeNode l = p.left, pp, lr;
857	>	if ((lr = p.left = l.right) != null)
858	>	lr.parent = p;
859	>	if ((pp = l.parent = p.parent) == null)
860	>	root = l;
861	>	else if (pp.right == p)
862	>	pp.right = l;
863	>	else
864	>	pp.left = l;
865	>	l.right = p;
866	>	p.parent = l;
867	>	}
868	>	}
869	>
870	>	/** From CLR */
871	>	private void fixAfterInsertion(TreeNode x) {
872	>	x.red = true;
873	>	TreeNode xp, xpp;
874	>	while (x != null && (xp = x.parent) != null && xp.red &&
875	>	(xpp = xp.parent) != null) {
876	>	TreeNode xppl = xpp.left;
877	>	if (xp == xppl) {
878	>	TreeNode y = xpp.right;
879	>	if (y != null && y.red) {
880	>	y.red = false;
881	>	xp.red = false;
882	>	xpp.red = true;
883	>	x = xpp;
884	>	}
885	>	else {
886	>	if (x == xp.right) {
887	>	x = xp;
888	>	rotateLeft(x);
889	>	xpp = (xp = x.parent) == null ? null : xp.parent;
890	>	}
891	>	if (xp != null) {
892	>	xp.red = false;
893	>	if (xpp != null) {
894	>	xpp.red = true;
895	>	rotateRight(xpp);
896	>	}
897	>	}
898	>	}
899	>	}
900	>	else {
901	>	TreeNode y = xppl;
902	>	if (y != null && y.red) {
903	>	y.red = false;
904	>	xp.red = false;
905	>	xpp.red = true;
906	>	x = xpp;
907	>	}
908	>	else {
909	>	if (x == xp.left) {
910	>	x = xp;
911	>	rotateRight(x);
912	>	xpp = (xp = x.parent) == null ? null : xp.parent;
913	>	}
914	>	if (xp != null) {
915	>	xp.red = false;
916	>	if (xpp != null) {
917	>	xpp.red = true;
918	>	rotateLeft(xpp);
919	>	}
920	>	}
921	>	}
922	>	}
923	>	}
924	>	TreeNode r = root;
925	>	if (r != null && r.red)
926	>	r.red = false;
927	>	}
928	>
929	>	/** From CLR */
930	>	private void fixAfterDeletion(TreeNode x) {
931	>	while (x != null) {
932	>	TreeNode xp, xpl;
933	>	if (x.red || (xp = x.parent) == null) {
934	>	x.red = false;
935	>	break;
936	>	}
937	>	if (x == (xpl = xp.left)) {
938	>	TreeNode sib = xp.right;
939	>	if (sib != null && sib.red) {
940	>	sib.red = false;
941	>	xp.red = true;
942	>	rotateLeft(xp);
943	>	sib = (xp = x.parent) == null ? null : xp.right;
944	>	}
945	>	if (sib == null)
946	>	x = xp;
947	>	else {
948	>	TreeNode sl = sib.left, sr = sib.right;
949	>	if ((sr == null || !sr.red) &&
950	>	(sl == null || !sl.red)) {
951	>	sib.red = true;
952	>	x = xp;
953	>	}
954	>	else {
955	>	if (sr == null || !sr.red) {
956	>	if (sl != null)
957	>	sl.red = false;
958	>	sib.red = true;
959	>	rotateRight(sib);
960	>	sib = (xp = x.parent) == null ? null : xp.right;
961	>	}
962	>	if (sib != null) {
963	>	sib.red = (xp == null)? false : xp.red;
964	>	if ((sr = sib.right) != null)
965	>	sr.red = false;
966	>	}
967	>	if (xp != null) {
968	>	xp.red = false;
969	>	rotateLeft(xp);
970	>	}
971	>	x = root;
972	>	}
973	>	}
974	>	}
975	>	else { // symmetric
976	>	TreeNode sib = xpl;
977	>	if (sib != null && sib.red) {
978	>	sib.red = false;
979	>	xp.red = true;
980	>	rotateRight(xp);
981	>	sib = (xp = x.parent) == null ? null : xp.left;
982	>	}
983	>	if (sib == null)
984	>	x = xp;
985	>	else {
986	>	TreeNode sl = sib.left, sr = sib.right;
987	>	if ((sl == null || !sl.red) &&
988	>	(sr == null || !sr.red)) {
989	>	sib.red = true;
990	>	x = xp;
991	>	}
992	>	else {
993	>	if (sl == null || !sl.red) {
994	>	if (sr != null)
995	>	sr.red = false;
996	>	sib.red = true;
997	>	rotateLeft(sib);
998	>	sib = (xp = x.parent) == null ? null : xp.left;
999	>	}
1000	>	if (sib != null) {
1001	>	sib.red = (xp == null)? false : xp.red;
1002	>	if ((sl = sib.left) != null)
1003	>	sl.red = false;
1004	>	}
1005	>	if (xp != null) {
1006	>	xp.red = false;
1007	>	rotateRight(xp);
1008	>	}
1009	>	x = root;
1010	>	}
1011	>	}
1012	>	}
1013	>	}
1014	>	}
1015		}
1016
1017	<	/* ---------------- Internal access and update methods -------------- */
1017	>	/* ---------------- Collision reduction methods -------------- */
1018
1019		/**
1020	<	* Applies a supplemental hash function to a given hashCode, which
1021	<	* defends against poor quality hash functions.  The result must
1022	<	* be have the top 2 bits clear. For reasonable performance, this
1023	<	* function must have good avalanche properties; i.e., that each
1024	<	* bit of the argument affects each bit of the result. (Although
1025	<	* we don't care about the unused top 2 bits.)
1020	>	* Spreads higher bits to lower, and also forces top 2 bits to 0.
1021	>	* Because the table uses power-of-two masking, sets of hashes
1022	>	* that vary only in bits above the current mask will always
1023	>	* collide. (Among known examples are sets of Float keys holding
1024	>	* consecutive whole numbers in small tables.)  To counter this,
1025	>	* we apply a transform that spreads the impact of higher bits
1026	>	* downward. There is a tradeoff between speed, utility, and
1027	>	* quality of bit-spreading. Because many common sets of hashes
1028	>	* are already reaonably distributed across bits (so don't benefit
1029	>	* from spreading), and because we use trees to handle large sets
1030	>	* of collisions in bins, we don't need excessively high quality.
1031		*/
1032		private static final int spread(int h) {
1033	<	// Apply base step of MurmurHash; see http://code.google.com/p/smhasher/
1034	<	h ^= h >>> 16;
1035	<	h *= 0x85ebca6b;
1036	<	h ^= h >>> 13;
1037	<	h *= 0xc2b2ae35;
1038	<	return ((h >>> 16) ^ h) & HASH_BITS; // mask out top bits
1033	>	h ^= (h >>> 18) ^ (h >>> 12);
1034	>	return (h ^ (h >>> 10)) & HASH_BITS;
1035	>	}
1036	>
1037	>	/**
1038	>	* Replaces a list bin with a tree bin. Call only when locked.
1039	>	* Fails to replace if the given key is non-comparable or table
1040	>	* is, or needs, resizing.
1041	>	*/
1042	>	private final void replaceWithTreeBin(Node[] tab, int index, Object key) {
1043	>	if ((key instanceof Comparable) &&
1044	>	(tab.length >= MAXIMUM_CAPACITY || counter.sum() < (long)sizeCtl)) {
1045	>	TreeBin t = new TreeBin();
1046	>	for (Node e = tabAt(tab, index); e != null; e = e.next)
1047	>	t.putTreeNode(e.hash & HASH_BITS, e.key, e.val);
1048	>	setTabAt(tab, index, new Node(MOVED, t, null, null));
1049	>	}
1050		}
1051
1052	+	/* ---------------- Internal access and update methods -------------- */
1053	+
1054		/** Implementation for get and containsKey */
1055		private final Object internalGet(Object k) {
1056		int h = spread(k.hashCode());
1057		retry: for (Node[] tab = table; tab != null;) {
1058	<	Node e; Object ek, ev; int eh;    // locals to read fields once
1058	>	Node e, p; Object ek, ev; int eh;      // locals to read fields once
1059		for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) {
1060		if ((eh = e.hash) == MOVED) {
1061	<	tab = (Node[])e.key;      // restart with new table
1062	<	continue retry;
1061	>	if ((ek = e.key) instanceof TreeBin)  // search TreeBin
1062	>	return ((TreeBin)ek).getValue(h, k);
1063	>	else {                        // restart with new table
1064	>	tab = (Node[])ek;
1065	>	continue retry;
1066	>	}
1067		}
1068	<	if ((eh & HASH_BITS) == h && (ev = e.val) != null &&
1069	<	((ek = e.key) == k || k.equals(ek)))
1068	>	else if ((eh & HASH_BITS) == h && (ev = e.val) != null &&
1069	>	((ek = e.key) == k || k.equals(ek)))
1070		return ev;
1071		}
1072		break;
#	Line 522 | Line 1074 | public class ConcurrentHashMapV8<K, V>
1074		return null;
1075		}
1076
525	–	/** Implementation for put and putIfAbsent */
526	–	private final Object internalPut(Object k, Object v, boolean replace) {
527	–	int h = spread(k.hashCode());
528	–	Object oldVal = null;               // previous value or null if none
529	–	for (Node[] tab = table;;) {
530	–	int i; Node f; int fh; Object fk, fv;
531	–	if (tab == null)
532	–	tab = initTable();
533	–	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
534	–	if (casTabAt(tab, i, null, new Node(h, k, v, null)))
535	–	break;                   // no lock when adding to empty bin
536	–	}
537	–	else if ((fh = f.hash) == MOVED)
538	–	tab = (Node[])f.key;
539	–	else if (!replace && (fh & HASH_BITS) == h && (fv = f.val) != null &&
540	–	((fk = f.key) == k || k.equals(fk))) {
541	–	oldVal = fv;                // precheck 1st node for putIfAbsent
542	–	break;
543	–	}
544	–	else if ((fh & LOCKED) != 0)
545	–	f.tryAwaitLock(tab, i);
546	–	else if (f.casHash(fh, fh | LOCKED)) {
547	–	boolean validated = false;
548	–	boolean checkSize = false;
549	–	try {
550	–	if (tabAt(tab, i) == f) {
551	–	validated = true;    // retry if 1st already deleted
552	–	for (Node e = f;;) {
553	–	Object ek, ev;
554	–	if ((e.hash & HASH_BITS) == h &&
555	–	(ev = e.val) != null &&
556	–	((ek = e.key) == k || k.equals(ek))) {
557	–	oldVal = ev;
558	–	if (replace)
559	–	e.val = v;
560	–	break;
561	–	}
562	–	Node last = e;
563	–	if ((e = e.next) == null) {
564	–	last.next = new Node(h, k, v, null);
565	–	if (last != f || tab.length <= 64)
566	–	checkSize = true;
567	–	break;
568	–	}
569	–	}
570	–	}
571	–	} finally {                  // unlock and signal if needed
572	–	if (!f.casHash(fh | LOCKED, fh)) {
573	–	f.hash = fh;
574	–	synchronized(f) { f.notifyAll(); };
575	–	}
576	–	}
577	–	if (validated) {
578	–	int sc;
579	–	if (checkSize && tab.length < MAXIMUM_CAPACITY &&
580	–	(sc = sizeCtl) >= 0 && counter.sum() >= (long)sc)
581	–	growTable();
582	–	break;
583	–	}
584	–	}
585	–	}
586	–	if (oldVal == null)
587	–	counter.increment();             // update counter outside of locks
588	–	return oldVal;
589	–	}
590	–
1077		/**
1078		* Implementation for the four public remove/replace methods:
1079		* Replaces node value with v, conditional upon match of cv if
#	Line 597 | Line 1083 | public class ConcurrentHashMapV8<K, V>
1083		int h = spread(k.hashCode());
1084		Object oldVal = null;
1085		for (Node[] tab = table;;) {
1086	<	Node f; int i, fh;
1086	>	Node f; int i, fh; Object fk;
1087		if (tab == null ||
1088		(f = tabAt(tab, i = (tab.length - 1) & h)) == null)
1089		break;
1090	<	else if ((fh = f.hash) == MOVED)
1091	<	tab = (Node[])f.key;
1090	>	else if ((fh = f.hash) == MOVED) {
1091	>	if ((fk = f.key) instanceof TreeBin) {
1092	>	TreeBin t = (TreeBin)fk;
1093	>	boolean validated = false;
1094	>	boolean deleted = false;
1095	>	t.acquire(0);
1096	>	try {
1097	>	if (tabAt(tab, i) == f) {
1098	>	validated = true;
1099	>	TreeNode p = t.getTreeNode(h, k, t.root);
1100	>	if (p != null) {
1101	>	Object pv = p.val;
1102	>	if (cv == null || cv == pv || cv.equals(pv)) {
1103	>	oldVal = pv;
1104	>	if ((p.val = v) == null) {
1105	>	deleted = true;
1106	>	t.deleteTreeNode(p);
1107	>	}
1108	>	}
1109	>	}
1110	>	}
1111	>	} finally {
1112	>	t.release(0);
1113	>	}
1114	>	if (validated) {
1115	>	if (deleted)
1116	>	counter.add(-1L);
1117	>	break;
1118	>	}
1119	>	}
1120	>	else
1121	>	tab = (Node[])fk;
1122	>	}
1123		else if ((fh & HASH_BITS) != h && f.next == null) // precheck
1124		break;                          // rules out possible existence
1125	<	else if ((fh & LOCKED) != 0)
1125	>	else if ((fh & LOCKED) != 0) {
1126	>	checkForResize();               // try resizing if can't get lock
1127		f.tryAwaitLock(tab, i);
1128	+	}
1129		else if (f.casHash(fh, fh | LOCKED)) {
1130		boolean validated = false;
1131		boolean deleted = false;
#	Line 639 | Line 1158 | public class ConcurrentHashMapV8<K, V>
1158		} finally {
1159		if (!f.casHash(fh | LOCKED, fh)) {
1160		f.hash = fh;
1161	<	synchronized(f) { f.notifyAll(); };
1161	>	synchronized (f) { f.notifyAll(); };
1162		}
1163		}
1164		if (validated) {
1165		if (deleted)
1166	<	counter.decrement();
1166	>	counter.add(-1L);
1167		break;
1168		}
1169		}
#	Line 652 | Line 1171 | public class ConcurrentHashMapV8<K, V>
1171		return oldVal;
1172		}
1173
1174	<	/** Implementation for computeIfAbsent and compute. Like put, but messier. */
1175	<	// Todo: Somehow reinstate non-termination check
1174	>	/*
1175	>	* Internal versions of the five insertion methods, each a
1176	>	* little more complicated than the last. All have
1177	>	* the same basic structure as the first (internalPut):
1178	>	*  1. If table uninitialized, create
1179	>	*  2. If bin empty, try to CAS new node
1180	>	*  3. If bin stale, use new table
1181	>	*  4. if bin converted to TreeBin, validate and relay to TreeBin methods
1182	>	*  5. Lock and validate; if valid, scan and add or update
1183	>	*
1184	>	* The others interweave other checks and/or alternative actions:
1185	>	*  * Plain put checks for and performs resize after insertion.
1186	>	*  * putIfAbsent prescans for mapping without lock (and fails to add
1187	>	*    if present), which also makes pre-emptive resize checks worthwhile.
1188	>	*  * computeIfAbsent extends form used in putIfAbsent with additional
1189	>	*    mechanics to deal with, calls, potential exceptions and null
1190	>	*    returns from function call.
1191	>	*  * compute uses the same function-call mechanics, but without
1192	>	*    the prescans
1193	>	*  * putAll attempts to pre-allocate enough table space
1194	>	*    and more lazily performs count updates and checks.
1195	>	*
1196	>	* Someday when details settle down a bit more, it might be worth
1197	>	* some factoring to reduce sprawl.
1198	>	*/
1199	>
1200	>	/** Implementation for put */
1201	>	private final Object internalPut(Object k, Object v) {
1202	>	int h = spread(k.hashCode());
1203	>	int count = 0;
1204	>	for (Node[] tab = table;;) {
1205	>	int i; Node f; int fh; Object fk;
1206	>	if (tab == null)
1207	>	tab = initTable();
1208	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1209	>	if (casTabAt(tab, i, null, new Node(h, k, v, null)))
1210	>	break;                   // no lock when adding to empty bin
1211	>	}
1212	>	else if ((fh = f.hash) == MOVED) {
1213	>	if ((fk = f.key) instanceof TreeBin) {
1214	>	TreeBin t = (TreeBin)fk;
1215	>	Object oldVal = null;
1216	>	t.acquire(0);
1217	>	try {
1218	>	if (tabAt(tab, i) == f) {
1219	>	count = 2;
1220	>	TreeNode p = t.putTreeNode(h, k, v);
1221	>	if (p != null) {
1222	>	oldVal = p.val;
1223	>	p.val = v;
1224	>	}
1225	>	}
1226	>	} finally {
1227	>	t.release(0);
1228	>	}
1229	>	if (count != 0) {
1230	>	if (oldVal != null)
1231	>	return oldVal;
1232	>	break;
1233	>	}
1234	>	}
1235	>	else
1236	>	tab = (Node[])fk;
1237	>	}
1238	>	else if ((fh & LOCKED) != 0) {
1239	>	checkForResize();
1240	>	f.tryAwaitLock(tab, i);
1241	>	}
1242	>	else if (f.casHash(fh, fh | LOCKED)) {
1243	>	Object oldVal = null;
1244	>	try {                        // needed in case equals() throws
1245	>	if (tabAt(tab, i) == f) {
1246	>	count = 1;
1247	>	for (Node e = f;; ++count) {
1248	>	Object ek, ev;
1249	>	if ((e.hash & HASH_BITS) == h &&
1250	>	(ev = e.val) != null &&
1251	>	((ek = e.key) == k || k.equals(ek))) {
1252	>	oldVal = ev;
1253	>	e.val = v;
1254	>	break;
1255	>	}
1256	>	Node last = e;
1257	>	if ((e = e.next) == null) {
1258	>	last.next = new Node(h, k, v, null);
1259	>	if (count >= TREE_THRESHOLD)
1260	>	replaceWithTreeBin(tab, i, k);
1261	>	break;
1262	>	}
1263	>	}
1264	>	}
1265	>	} finally {                  // unlock and signal if needed
1266	>	if (!f.casHash(fh | LOCKED, fh)) {
1267	>	f.hash = fh;
1268	>	synchronized (f) { f.notifyAll(); };
1269	>	}
1270	>	}
1271	>	if (count != 0) {
1272	>	if (oldVal != null)
1273	>	return oldVal;
1274	>	if (tab.length <= 64)
1275	>	count = 2;
1276	>	break;
1277	>	}
1278	>	}
1279	>	}
1280	>	counter.add(1L);
1281	>	if (count > 1)
1282	>	checkForResize();
1283	>	return null;
1284	>	}
1285	>
1286	>	/** Implementation for putIfAbsent */
1287	>	private final Object internalPutIfAbsent(Object k, Object v) {
1288	>	int h = spread(k.hashCode());
1289	>	int count = 0;
1290	>	for (Node[] tab = table;;) {
1291	>	int i; Node f; int fh; Object fk, fv;
1292	>	if (tab == null)
1293	>	tab = initTable();
1294	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1295	>	if (casTabAt(tab, i, null, new Node(h, k, v, null)))
1296	>	break;
1297	>	}
1298	>	else if ((fh = f.hash) == MOVED) {
1299	>	if ((fk = f.key) instanceof TreeBin) {
1300	>	TreeBin t = (TreeBin)fk;
1301	>	Object oldVal = null;
1302	>	t.acquire(0);
1303	>	try {
1304	>	if (tabAt(tab, i) == f) {
1305	>	count = 2;
1306	>	TreeNode p = t.putTreeNode(h, k, v);
1307	>	if (p != null)
1308	>	oldVal = p.val;
1309	>	}
1310	>	} finally {
1311	>	t.release(0);
1312	>	}
1313	>	if (count != 0) {
1314	>	if (oldVal != null)
1315	>	return oldVal;
1316	>	break;
1317	>	}
1318	>	}
1319	>	else
1320	>	tab = (Node[])fk;
1321	>	}
1322	>	else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
1323	>	((fk = f.key) == k || k.equals(fk)))
1324	>	return fv;
1325	>	else {
1326	>	Node g = f.next;
1327	>	if (g != null) { // at least 2 nodes -- search and maybe resize
1328	>	for (Node e = g;;) {
1329	>	Object ek, ev;
1330	>	if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
1331	>	((ek = e.key) == k || k.equals(ek)))
1332	>	return ev;
1333	>	if ((e = e.next) == null) {
1334	>	checkForResize();
1335	>	break;
1336	>	}
1337	>	}
1338	>	}
1339	>	if (((fh = f.hash) & LOCKED) != 0) {
1340	>	checkForResize();
1341	>	f.tryAwaitLock(tab, i);
1342	>	}
1343	>	else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1344	>	Object oldVal = null;
1345	>	try {
1346	>	if (tabAt(tab, i) == f) {
1347	>	count = 1;
1348	>	for (Node e = f;; ++count) {
1349	>	Object ek, ev;
1350	>	if ((e.hash & HASH_BITS) == h &&
1351	>	(ev = e.val) != null &&
1352	>	((ek = e.key) == k || k.equals(ek))) {
1353	>	oldVal = ev;
1354	>	break;
1355	>	}
1356	>	Node last = e;
1357	>	if ((e = e.next) == null) {
1358	>	last.next = new Node(h, k, v, null);
1359	>	if (count >= TREE_THRESHOLD)
1360	>	replaceWithTreeBin(tab, i, k);
1361	>	break;
1362	>	}
1363	>	}
1364	>	}
1365	>	} finally {
1366	>	if (!f.casHash(fh | LOCKED, fh)) {
1367	>	f.hash = fh;
1368	>	synchronized (f) { f.notifyAll(); };
1369	>	}
1370	>	}
1371	>	if (count != 0) {
1372	>	if (oldVal != null)
1373	>	return oldVal;
1374	>	if (tab.length <= 64)
1375	>	count = 2;
1376	>	break;
1377	>	}
1378	>	}
1379	>	}
1380	>	}
1381	>	counter.add(1L);
1382	>	if (count > 1)
1383	>	checkForResize();
1384	>	return null;
1385	>	}
1386	>
1387	>	/** Implementation for computeIfAbsent */
1388	>	private final Object internalComputeIfAbsent(K k,
1389	>	MappingFunction<? super K, ?> mf) {
1390	>	int h = spread(k.hashCode());
1391	>	Object val = null;
1392	>	int count = 0;
1393	>	for (Node[] tab = table;;) {
1394	>	Node f; int i, fh; Object fk, fv;
1395	>	if (tab == null)
1396	>	tab = initTable();
1397	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1398	>	Node node = new Node(fh = h | LOCKED, k, null, null);
1399	>	if (casTabAt(tab, i, null, node)) {
1400	>	count = 1;
1401	>	try {
1402	>	if ((val = mf.map(k)) != null)
1403	>	node.val = val;
1404	>	} finally {
1405	>	if (val == null)
1406	>	setTabAt(tab, i, null);
1407	>	if (!node.casHash(fh, h)) {
1408	>	node.hash = h;
1409	>	synchronized (node) { node.notifyAll(); };
1410	>	}
1411	>	}
1412	>	}
1413	>	if (count != 0)
1414	>	break;
1415	>	}
1416	>	else if ((fh = f.hash) == MOVED) {
1417	>	if ((fk = f.key) instanceof TreeBin) {
1418	>	TreeBin t = (TreeBin)fk;
1419	>	boolean added = false;
1420	>	t.acquire(0);
1421	>	try {
1422	>	if (tabAt(tab, i) == f) {
1423	>	count = 1;
1424	>	TreeNode p = t.getTreeNode(h, k, t.root);
1425	>	if (p != null)
1426	>	val = p.val;
1427	>	else if ((val = mf.map(k)) != null) {
1428	>	added = true;
1429	>	count = 2;
1430	>	t.putTreeNode(h, k, val);
1431	>	}
1432	>	}
1433	>	} finally {
1434	>	t.release(0);
1435	>	}
1436	>	if (count != 0) {
1437	>	if (!added)
1438	>	return val;
1439	>	break;
1440	>	}
1441	>	}
1442	>	else
1443	>	tab = (Node[])fk;
1444	>	}
1445	>	else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
1446	>	((fk = f.key) == k || k.equals(fk)))
1447	>	return fv;
1448	>	else {
1449	>	Node g = f.next;
1450	>	if (g != null) {
1451	>	for (Node e = g;;) {
1452	>	Object ek, ev;
1453	>	if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
1454	>	((ek = e.key) == k || k.equals(ek)))
1455	>	return ev;
1456	>	if ((e = e.next) == null) {
1457	>	checkForResize();
1458	>	break;
1459	>	}
1460	>	}
1461	>	}
1462	>	if (((fh = f.hash) & LOCKED) != 0) {
1463	>	checkForResize();
1464	>	f.tryAwaitLock(tab, i);
1465	>	}
1466	>	else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1467	>	boolean added = false;
1468	>	try {
1469	>	if (tabAt(tab, i) == f) {
1470	>	count = 1;
1471	>	for (Node e = f;; ++count) {
1472	>	Object ek, ev;
1473	>	if ((e.hash & HASH_BITS) == h &&
1474	>	(ev = e.val) != null &&
1475	>	((ek = e.key) == k || k.equals(ek))) {
1476	>	val = ev;
1477	>	break;
1478	>	}
1479	>	Node last = e;
1480	>	if ((e = e.next) == null) {
1481	>	if ((val = mf.map(k)) != null) {
1482	>	added = true;
1483	>	last.next = new Node(h, k, val, null);
1484	>	if (count >= TREE_THRESHOLD)
1485	>	replaceWithTreeBin(tab, i, k);
1486	>	}
1487	>	break;
1488	>	}
1489	>	}
1490	>	}
1491	>	} finally {
1492	>	if (!f.casHash(fh | LOCKED, fh)) {
1493	>	f.hash = fh;
1494	>	synchronized (f) { f.notifyAll(); };
1495	>	}
1496	>	}
1497	>	if (count != 0) {
1498	>	if (!added)
1499	>	return val;
1500	>	if (tab.length <= 64)
1501	>	count = 2;
1502	>	break;
1503	>	}
1504	>	}
1505	>	}
1506	>	}
1507	>	if (val == null)
1508	>	throw new NullPointerException();
1509	>	counter.add(1L);
1510	>	if (count > 1)
1511	>	checkForResize();
1512	>	return val;
1513	>	}
1514	>
1515	>	/** Implementation for compute */
1516		@SuppressWarnings("unchecked")
1517	<	private final V internalCompute(K k,
1518	<	MappingFunction<? super K, ? extends V> fn,
660	<	boolean replace) {
1517	>	private final Object internalCompute(K k,
1518	>	RemappingFunction<? super K, V> mf) {
1519		int h = spread(k.hashCode());
1520	<	V val = null;
1520	>	Object val = null;
1521		boolean added = false;
1522	<	Node[] tab = table;
1523	<	outer:for (;;) {
1524	<	Node f; int i, fh; Object fk, fv;
1522	>	int count = 0;
1523	>	for (Node[] tab = table;;) {
1524	>	Node f; int i, fh; Object fk;
1525		if (tab == null)
1526		tab = initTable();
1527		else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
1528		Node node = new Node(fh = h | LOCKED, k, null, null);
671	–	boolean validated = false;
1529		if (casTabAt(tab, i, null, node)) {
673	–	validated = true;
1530		try {
1531	<	val = fn.map(k);
1532	<	if (val != null) {
1531	>	count = 1;
1532	>	if ((val = mf.remap(k, null)) != null) {
1533		node.val = val;
1534		added = true;
1535		}
#	Line 681 | Line 1537 | public class ConcurrentHashMapV8<K, V>
1537		if (!added)
1538		setTabAt(tab, i, null);
1539		if (!node.casHash(fh, h)) {
1540	<	node.hash = fh;
1541	<	synchronized(node) { node.notifyAll(); };
1540	>	node.hash = h;
1541	>	synchronized (node) { node.notifyAll(); };
1542		}
1543		}
1544		}
1545	<	if (validated)
1545	>	if (count != 0)
1546		break;
1547		}
1548	<	else if ((fh = f.hash) == MOVED)
1549	<	tab = (Node[])f.key;
1550	<	else if (!replace && (fh & HASH_BITS) == h && (fv = f.val) != null &&
1551	<	((fk = f.key) == k || k.equals(fk))) {
1552	<	if (tabAt(tab, i) == f) {
1553	<	val = (V)fv;
1554	<	break;
1548	>	else if ((fh = f.hash) == MOVED) {
1549	>	if ((fk = f.key) instanceof TreeBin) {
1550	>	TreeBin t = (TreeBin)fk;
1551	>	t.acquire(0);
1552	>	try {
1553	>	if (tabAt(tab, i) == f) {
1554	>	count = 1;
1555	>	TreeNode p = t.getTreeNode(h, k, t.root);
1556	>	Object pv = (p == null)? null : p.val;
1557	>	if ((val = mf.remap(k, (V)pv)) != null) {
1558	>	if (p != null)
1559	>	p.val = val;
1560	>	else {
1561	>	count = 2;
1562	>	added = true;
1563	>	t.putTreeNode(h, k, val);
1564	>	}
1565	>	}
1566	>	}
1567	>	} finally {
1568	>	t.release(0);
1569	>	}
1570	>	if (count != 0)
1571	>	break;
1572		}
1573	+	else
1574	+	tab = (Node[])fk;
1575		}
1576	<	else if ((fh & LOCKED) != 0)
1576	>	else if ((fh & LOCKED) != 0) {
1577	>	checkForResize();
1578		f.tryAwaitLock(tab, i);
1579	+	}
1580		else if (f.casHash(fh, fh | LOCKED)) {
704	–	boolean validated = false;
705	–	boolean checkSize = false;
1581		try {
1582		if (tabAt(tab, i) == f) {
1583	<	validated = true;
1584	<	for (Node e = f;;) {
1585	<	Object ek, ev, v;
1583	>	count = 1;
1584	>	for (Node e = f;; ++count) {
1585	>	Object ek, ev;
1586		if ((e.hash & HASH_BITS) == h &&
1587		(ev = e.val) != null &&
1588		((ek = e.key) == k || k.equals(ek))) {
1589	<	if (replace && (v = fn.map(k)) != null)
1590	<	ev = e.val = v;
1591	<	val = (V)ev;
1589	>	val = mf.remap(k, (V)ev);
1590	>	if (val != null)
1591	>	e.val = val;
1592		break;
1593		}
1594		Node last = e;
1595		if ((e = e.next) == null) {
1596	<	if ((val = fn.map(k)) != null) {
1596	>	if ((val = mf.remap(k, null)) != null) {
1597		last.next = new Node(h, k, val, null);
1598		added = true;
1599	<	if (last != f || tab.length <= 64)
1600	<	checkSize = true;
1599	>	if (count >= TREE_THRESHOLD)
1600	>	replaceWithTreeBin(tab, i, k);
1601		}
1602		break;
1603		}
#	Line 731 | Line 1606 | public class ConcurrentHashMapV8<K, V>
1606		} finally {
1607		if (!f.casHash(fh | LOCKED, fh)) {
1608		f.hash = fh;
1609	<	synchronized(f) { f.notifyAll(); };
1609	>	synchronized (f) { f.notifyAll(); };
1610		}
1611		}
1612	<	if (validated) {
1613	<	int sc;
1614	<	if (checkSize && tab.length < MAXIMUM_CAPACITY &&
740	<	(sc = sizeCtl) >= 0 && counter.sum() >= (long)sc)
741	<	growTable();
1612	>	if (count != 0) {
1613	>	if (tab.length <= 64)
1614	>	count = 2;
1615		break;
1616		}
1617		}
1618		}
1619	<	if (added)
1620	<	counter.increment();
1619	>	if (val == null)
1620	>	throw new NullPointerException();
1621	>	if (added) {
1622	>	counter.add(1L);
1623	>	if (count > 1)
1624	>	checkForResize();
1625	>	}
1626		return val;
1627		}
1628
1629	<	/**
1630	<	* Implementation for clear. Steps through each bin, removing all nodes.
1631	<	*/
1632	<	private final void internalClear() {
1633	<	long delta = 0L; // negative number of deletions
1634	<	int i = 0;
1635	<	Node[] tab = table;
1636	<	while (tab != null && i < tab.length) {
1637	<	int fh;
1638	<	Node f = tabAt(tab, i);
1639	<	if (f == null)
1640	<	++i;
1641	<	else if ((fh = f.hash) == MOVED)
1642	<	tab = (Node[])f.key;
1643	<	else if ((fh & LOCKED) != 0)
1644	<	f.tryAwaitLock(tab, i);
1645	<	else if (f.casHash(fh, fh | LOCKED)) {
1646	<	boolean validated = false;
1647	<	try {
1648	<	if (tabAt(tab, i) == f) {
1649	<	validated = true;
1650	<	for (Node e = f; e != null; e = e.next) {
1651	<	if (e.val != null) { // currently always true
1652	<	e.val = null;
1653	<	--delta;
1629	>	/** Implementation for putAll */
1630	>	private final void internalPutAll(Map<?, ?> m) {
1631	>	tryPresize(m.size());
1632	>	long delta = 0L;     // number of uncommitted additions
1633	>	boolean npe = false; // to throw exception on exit for nulls
1634	>	try {                // to clean up counts on other exceptions
1635	>	for (Map.Entry<?, ?> entry : m.entrySet()) {
1636	>	Object k, v;
1637	>	if (entry == null || (k = entry.getKey()) == null ||
1638	>	(v = entry.getValue()) == null) {
1639	>	npe = true;
1640	>	break;
1641	>	}
1642	>	int h = spread(k.hashCode());
1643	>	for (Node[] tab = table;;) {
1644	>	int i; Node f; int fh; Object fk;
1645	>	if (tab == null)
1646	>	tab = initTable();
1647	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
1648	>	if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
1649	>	++delta;
1650	>	break;
1651	>	}
1652	>	}
1653	>	else if ((fh = f.hash) == MOVED) {
1654	>	if ((fk = f.key) instanceof TreeBin) {
1655	>	TreeBin t = (TreeBin)fk;
1656	>	boolean validated = false;
1657	>	t.acquire(0);
1658	>	try {
1659	>	if (tabAt(tab, i) == f) {
1660	>	validated = true;
1661	>	TreeNode p = t.getTreeNode(h, k, t.root);
1662	>	if (p != null)
1663	>	p.val = v;
1664	>	else {
1665	>	t.putTreeNode(h, k, v);
1666	>	++delta;
1667	>	}
1668	>	}
1669	>	} finally {
1670	>	t.release(0);
1671		}
1672	+	if (validated)
1673	+	break;
1674		}
1675	<	setTabAt(tab, i, null);
1675	>	else
1676	>	tab = (Node[])fk;
1677		}
1678	<	} finally {
1679	<	if (!f.casHash(fh | LOCKED, fh)) {
1680	<	f.hash = fh;
1681	<	synchronized(f) { f.notifyAll(); };
1678	>	else if ((fh & LOCKED) != 0) {
1679	>	counter.add(delta);
1680	>	delta = 0L;
1681	>	checkForResize();
1682	>	f.tryAwaitLock(tab, i);
1683	>	}
1684	>	else if (f.casHash(fh, fh | LOCKED)) {
1685	>	int count = 0;
1686	>	try {
1687	>	if (tabAt(tab, i) == f) {
1688	>	count = 1;
1689	>	for (Node e = f;; ++count) {
1690	>	Object ek, ev;
1691	>	if ((e.hash & HASH_BITS) == h &&
1692	>	(ev = e.val) != null &&
1693	>	((ek = e.key) == k || k.equals(ek))) {
1694	>	e.val = v;
1695	>	break;
1696	>	}
1697	>	Node last = e;
1698	>	if ((e = e.next) == null) {
1699	>	++delta;
1700	>	last.next = new Node(h, k, v, null);
1701	>	if (count >= TREE_THRESHOLD)
1702	>	replaceWithTreeBin(tab, i, k);
1703	>	break;
1704	>	}
1705	>	}
1706	>	}
1707	>	} finally {
1708	>	if (!f.casHash(fh | LOCKED, fh)) {
1709	>	f.hash = fh;
1710	>	synchronized (f) { f.notifyAll(); };
1711	>	}
1712	>	}
1713	>	if (count != 0) {
1714	>	if (count > 1) {
1715	>	counter.add(delta);
1716	>	delta = 0L;
1717	>	checkForResize();
1718	>	}
1719	>	break;
1720	>	}
1721		}
1722		}
786	–	if (validated)
787	–	++i;
1723		}
1724	+	} finally {
1725	+	if (delta != 0)
1726	+	counter.add(delta);
1727		}
1728	<	counter.add(delta);
1728	>	if (npe)
1729	>	throw new NullPointerException();
1730		}
1731
1732	<	/* ----------------Table Initialization and Resizing -------------- */
1732	>	/* ---------------- Table Initialization and Resizing -------------- */
1733
1734		/**
1735		* Returns a power of two table size for the given desired capacity.
#	Line 819 | Line 1758 | public class ConcurrentHashMapV8<K, V>
1758		if ((tab = table) == null) {
1759		int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
1760		tab = table = new Node[n];
1761	<	sc = n - (n >>> 2) - 1;
1761	>	sc = n - (n >>> 2);
1762		}
1763		} finally {
1764		sizeCtl = sc;
#	Line 831 | Line 1770 | public class ConcurrentHashMapV8<K, V>
1770		}
1771
1772		/**
1773	<	* If not already resizing, creates next table and transfers bins.
1774	<	* Rechecks occupancy after a transfer to see if another resize is
1775	<	* already needed because resizings are lagging additions.
1776	<	*/
1777	<	private final void growTable() {
1778	<	int sc = sizeCtl;
1779	<	if (sc >= 0 && UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1773	>	* If table is too small and not already resizing, creates next
1774	>	* table and transfers bins.  Rechecks occupancy after a transfer
1775	>	* to see if another resize is already needed because resizings
1776	>	* are lagging additions.
1777	>	*/
1778	>	private final void checkForResize() {
1779	>	Node[] tab; int n, sc;
1780	>	while ((tab = table) != null &&
1781	>	(n = tab.length) < MAXIMUM_CAPACITY &&
1782	>	(sc = sizeCtl) >= 0 && counter.sum() >= (long)sc &&
1783	>	UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1784		try {
1785	<	Node[] tab; int n;
843	<	while ((tab = table) != null &&
844	<	(n = tab.length) > 0 && n < MAXIMUM_CAPACITY &&
845	<	counter.sum() >= (long)sc) {
1785	>	if (tab == table) {
1786		table = rebuild(tab);
1787	<	sc = (n << 1) - (n >>> 1) - 1;
1787	>	sc = (n << 1) - (n >>> 1);
1788		}
1789		} finally {
1790		sizeCtl = sc;
#	Line 852 | Line 1792 | public class ConcurrentHashMapV8<K, V>
1792		}
1793		}
1794
1795	+	/**
1796	+	* Tries to presize table to accommodate the given number of elements.
1797	+	*
1798	+	* @param size number of elements (doesn't need to be perfectly accurate)
1799	+	*/
1800	+	private final void tryPresize(int size) {
1801	+	int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1802	+	tableSizeFor(size + (size >>> 1) + 1);
1803	+	int sc;
1804	+	while ((sc = sizeCtl) >= 0) {
1805	+	Node[] tab = table; int n;
1806	+	if (tab == null || (n = tab.length) == 0) {
1807	+	n = (sc > c) ? sc : c;
1808	+	if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1809	+	try {
1810	+	if (table == tab) {
1811	+	table = new Node[n];
1812	+	sc = n - (n >>> 2);
1813	+	}
1814	+	} finally {
1815	+	sizeCtl = sc;
1816	+	}
1817	+	}
1818	+	}
1819	+	else if (c <= sc || n >= MAXIMUM_CAPACITY)
1820	+	break;
1821	+	else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1822	+	try {
1823	+	if (table == tab) {
1824	+	table = rebuild(tab);
1825	+	sc = (n << 1) - (n >>> 1);
1826	+	}
1827	+	} finally {
1828	+	sizeCtl = sc;
1829	+	}
1830	+	}
1831	+	}
1832	+	}
1833	+
1834		/*
1835		* Moves and/or copies the nodes in each bin to new table. See
1836		* above for explanation.
#	Line 876 | Line 1855 | public class ConcurrentHashMapV8<K, V>
1855		continue;
1856		}
1857		else {             // transiently use a locked forwarding node
1858	<	Node g =  new Node(MOVED|LOCKED, nextTab, null, null);
1858	>	Node g = new Node(MOVED|LOCKED, nextTab, null, null);
1859		if (!casTabAt(tab, i, f, g))
1860		continue;
1861		setTabAt(nextTab, i, null);
#	Line 884 | Line 1863 | public class ConcurrentHashMapV8<K, V>
1863		setTabAt(tab, i, fwd);
1864		if (!g.casHash(MOVED|LOCKED, MOVED)) {
1865		g.hash = MOVED;
1866	<	synchronized(g) { g.notifyAll(); }
1866	>	synchronized (g) { g.notifyAll(); }
1867		}
1868		}
1869		}
1870	<	else if (((fh = f.hash) & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) {
1870	>	else if ((fh = f.hash) == MOVED) {
1871	>	Object fk = f.key;
1872	>	if (fk instanceof TreeBin) {
1873	>	TreeBin t = (TreeBin)fk;
1874	>	boolean validated = false;
1875	>	t.acquire(0);
1876	>	try {
1877	>	if (tabAt(tab, i) == f) {
1878	>	validated = true;
1879	>	splitTreeBin(nextTab, i, t);
1880	>	setTabAt(tab, i, fwd);
1881	>	}
1882	>	} finally {
1883	>	t.release(0);
1884	>	}
1885	>	if (!validated)
1886	>	continue;
1887	>	}
1888	>	}
1889	>	else if ((fh & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) {
1890		boolean validated = false;
1891		try {              // split to lo and hi lists; copying as needed
1892		if (tabAt(tab, i) == f) {
1893		validated = true;
1894	<	Node e = f, lastRun = f;
897	<	Node lo = null, hi = null;
898	<	int runBit = e.hash & n;
899	<	for (Node p = e.next; p != null; p = p.next) {
900	<	int b = p.hash & n;
901	<	if (b != runBit) {
902	<	runBit = b;
903	<	lastRun = p;
904	<	}
905	<	}
906	<	if (runBit == 0)
907	<	lo = lastRun;
908	<	else
909	<	hi = lastRun;
910	<	for (Node p = e; p != lastRun; p = p.next) {
911	<	int ph = p.hash & HASH_BITS;
912	<	Object pk = p.key, pv = p.val;
913	<	if ((ph & n) == 0)
914	<	lo = new Node(ph, pk, pv, lo);
915	<	else
916	<	hi = new Node(ph, pk, pv, hi);
917	<	}
918	<	setTabAt(nextTab, i, lo);
919	<	setTabAt(nextTab, i + n, hi);
1894	>	splitBin(nextTab, i, f);
1895		setTabAt(tab, i, fwd);
1896		}
1897		} finally {
1898		if (!f.casHash(fh | LOCKED, fh)) {
1899		f.hash = fh;
1900	<	synchronized(f) { f.notifyAll(); };
1900	>	synchronized (f) { f.notifyAll(); };
1901		}
1902		}
1903		if (!validated)
#	Line 961 | Line 1936 | public class ConcurrentHashMapV8<K, V>
1936		}
1937		}
1938
1939	+	/**
1940	+	* Split a normal bin with list headed by e into lo and hi parts;
1941	+	* install in given table
1942	+	*/
1943	+	private static void splitBin(Node[] nextTab, int i, Node e) {
1944	+	int bit = nextTab.length >>> 1; // bit to split on
1945	+	int runBit = e.hash & bit;
1946	+	Node lastRun = e, lo = null, hi = null;
1947	+	for (Node p = e.next; p != null; p = p.next) {
1948	+	int b = p.hash & bit;
1949	+	if (b != runBit) {
1950	+	runBit = b;
1951	+	lastRun = p;
1952	+	}
1953	+	}
1954	+	if (runBit == 0)
1955	+	lo = lastRun;
1956	+	else
1957	+	hi = lastRun;
1958	+	for (Node p = e; p != lastRun; p = p.next) {
1959	+	int ph = p.hash & HASH_BITS;
1960	+	Object pk = p.key, pv = p.val;
1961	+	if ((ph & bit) == 0)
1962	+	lo = new Node(ph, pk, pv, lo);
1963	+	else
1964	+	hi = new Node(ph, pk, pv, hi);
1965	+	}
1966	+	setTabAt(nextTab, i, lo);
1967	+	setTabAt(nextTab, i + bit, hi);
1968	+	}
1969	+
1970	+	/**
1971	+	* Split a tree bin into lo and hi parts; install in given table
1972	+	*/
1973	+	private static void splitTreeBin(Node[] nextTab, int i, TreeBin t) {
1974	+	int bit = nextTab.length >>> 1;
1975	+	TreeBin lt = new TreeBin();
1976	+	TreeBin ht = new TreeBin();
1977	+	int lc = 0, hc = 0;
1978	+	for (Node e = t.first; e != null; e = e.next) {
1979	+	int h = e.hash & HASH_BITS;
1980	+	Object k = e.key, v = e.val;
1981	+	if ((h & bit) == 0) {
1982	+	++lc;
1983	+	lt.putTreeNode(h, k, v);
1984	+	}
1985	+	else {
1986	+	++hc;
1987	+	ht.putTreeNode(h, k, v);
1988	+	}
1989	+	}
1990	+	Node ln, hn; // throw away trees if too small
1991	+	if (lc <= (TREE_THRESHOLD >>> 1)) {
1992	+	ln = null;
1993	+	for (Node p = lt.first; p != null; p = p.next)
1994	+	ln = new Node(p.hash, p.key, p.val, ln);
1995	+	}
1996	+	else
1997	+	ln = new Node(MOVED, lt, null, null);
1998	+	setTabAt(nextTab, i, ln);
1999	+	if (hc <= (TREE_THRESHOLD >>> 1)) {
2000	+	hn = null;
2001	+	for (Node p = ht.first; p != null; p = p.next)
2002	+	hn = new Node(p.hash, p.key, p.val, hn);
2003	+	}
2004	+	else
2005	+	hn = new Node(MOVED, ht, null, null);
2006	+	setTabAt(nextTab, i + bit, hn);
2007	+	}
2008	+
2009	+	/**
2010	+	* Implementation for clear. Steps through each bin, removing all
2011	+	* nodes.
2012	+	*/
2013	+	private final void internalClear() {
2014	+	long delta = 0L; // negative number of deletions
2015	+	int i = 0;
2016	+	Node[] tab = table;
2017	+	while (tab != null && i < tab.length) {
2018	+	int fh; Object fk;
2019	+	Node f = tabAt(tab, i);
2020	+	if (f == null)
2021	+	++i;
2022	+	else if ((fh = f.hash) == MOVED) {
2023	+	if ((fk = f.key) instanceof TreeBin) {
2024	+	TreeBin t = (TreeBin)fk;
2025	+	t.acquire(0);
2026	+	try {
2027	+	if (tabAt(tab, i) == f) {
2028	+	for (Node p = t.first; p != null; p = p.next) {
2029	+	p.val = null;
2030	+	--delta;
2031	+	}
2032	+	t.first = null;
2033	+	t.root = null;
2034	+	++i;
2035	+	}
2036	+	} finally {
2037	+	t.release(0);
2038	+	}
2039	+	}
2040	+	else
2041	+	tab = (Node[])fk;
2042	+	}
2043	+	else if ((fh & LOCKED) != 0) {
2044	+	counter.add(delta); // opportunistically update count
2045	+	delta = 0L;
2046	+	f.tryAwaitLock(tab, i);
2047	+	}
2048	+	else if (f.casHash(fh, fh | LOCKED)) {
2049	+	try {
2050	+	if (tabAt(tab, i) == f) {
2051	+	for (Node e = f; e != null; e = e.next) {
2052	+	e.val = null;
2053	+	--delta;
2054	+	}
2055	+	setTabAt(tab, i, null);
2056	+	++i;
2057	+	}
2058	+	} finally {
2059	+	if (!f.casHash(fh | LOCKED, fh)) {
2060	+	f.hash = fh;
2061	+	synchronized (f) { f.notifyAll(); };
2062	+	}
2063	+	}
2064	+	}
2065	+	}
2066	+	if (delta != 0)
2067	+	counter.add(delta);
2068	+	}
2069	+
2070		/* ----------------Table Traversal -------------- */
2071
2072		/**
#	Line 969 | Line 2075 | public class ConcurrentHashMapV8<K, V>
2075		*
2076		* At each step, the iterator snapshots the key ("nextKey") and
2077		* value ("nextVal") of a valid node (i.e., one that, at point of
2078	<	* snapshot, has a nonnull user value). Because val fields can
2078	>	* snapshot, has a non-null user value). Because val fields can
2079		* change (including to null, indicating deletion), field nextVal
2080		* might not be accurate at point of use, but still maintains the
2081		* weak consistency property of holding a value that was once
#	Line 982 | Line 2088 | public class ConcurrentHashMapV8<K, V>
2088		* value, or key-value pairs as return values of Iterator.next(),
2089		* and encapsulate the it.next check as hasNext();
2090		*
2091	<	* The iterator visits each valid node that was reachable upon
2092	<	* iterator construction once. It might miss some that were added
2093	<	* to a bin after the bin was visited, which is OK wrt consistency
2094	<	* guarantees. Maintaining this property in the face of possible
2095	<	* ongoing resizes requires a fair amount of bookkeeping state
2096	<	* that is difficult to optimize away amidst volatile accesses.
2097	<	* Even so, traversal maintains reasonable throughput.
2091	>	* The iterator visits once each still-valid node that was
2092	>	* reachable upon iterator construction. It might miss some that
2093	>	* were added to a bin after the bin was visited, which is OK wrt
2094	>	* consistency guarantees. Maintaining this property in the face
2095	>	* of possible ongoing resizes requires a fair amount of
2096	>	* bookkeeping state that is difficult to optimize away amidst
2097	>	* volatile accesses.  Even so, traversal maintains reasonable
2098	>	* throughput.
2099		*
2100		* Normally, iteration proceeds bin-by-bin traversing lists.
2101		* However, if the table has been resized, then all future steps
#	Line 1026 | Line 2133 | public class ConcurrentHashMapV8<K, V>
2133		this.tab = tab;
2134		baseSize = (tab == null) ? 0 : tab.length;
2135		baseLimit = (hi <= baseSize) ? hi : baseSize;
2136	<	index = baseIndex = lo;
2136	>	index = baseIndex = (lo >= 0) ? lo : 0;
2137		next = null;
2138		advance();
2139		}
#	Line 1038 | Line 2145 | public class ConcurrentHashMapV8<K, V>
2145		if (e != null)                  // advance past used/skipped node
2146		e = e.next;
2147		while (e == null) {             // get to next non-null bin
2148	<	Node[] t; int b, i, n;      // checks must use locals
2148	>	Node[] t; int b, i, n; Object ek; // checks must use locals
2149		if ((b = baseIndex) >= baseLimit || (i = index) < 0 ||
2150		(t = tab) == null || i >= (n = t.length))
2151		break outer;
2152	<	else if ((e = tabAt(t, i)) != null && e.hash == MOVED)
2153	<	tab = (Node[])e.key;    // restarts due to null val
2154	<	else                        // visit upper slots if present
2155	<	index = (i += baseSize) < n ? i : (baseIndex = b + 1);
2152	>	else if ((e = tabAt(t, i)) != null && e.hash == MOVED) {
2153	>	if ((ek = e.key) instanceof TreeBin)
2154	>	e = ((TreeBin)ek).first;
2155	>	else {
2156	>	tab = (Node[])ek;
2157	>	continue;           // restarts due to null val
2158	>	}
2159	>	}                           // visit upper slots if present
2160	>	index = (i += baseSize) < n ? i : (baseIndex = b + 1);
2161		}
2162		nextKey = e.key;
2163		} while ((nextVal = e.val) == null);// skip deleted or special nodes
#	Line 1090 | Line 2202 | public class ConcurrentHashMapV8<K, V>
2202		public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) {
2203		this.counter = new LongAdder();
2204		this.sizeCtl = DEFAULT_CAPACITY;
2205	<	putAll(m);
2205	>	internalPutAll(m);
2206		}
2207
2208		/**
#	Line 1137 | Line 2249 | public class ConcurrentHashMapV8<K, V>
2249		if (initialCapacity < concurrencyLevel)   // Use at least as many bins
2250		initialCapacity = concurrencyLevel;   // as estimated threads
2251		long size = (long)(1.0 + (long)initialCapacity / loadFactor);
2252	<	int cap =  ((size >= (long)MAXIMUM_CAPACITY) ?
2253	<	MAXIMUM_CAPACITY: tableSizeFor((int)size));
2252	>	int cap = ((size >= (long)MAXIMUM_CAPACITY) ?
2253	>	MAXIMUM_CAPACITY: tableSizeFor((int)size));
2254		this.counter = new LongAdder();
2255		this.sizeCtl = cap;
2256		}
#	Line 1257 | Line 2369 | public class ConcurrentHashMapV8<K, V>
2369		public V put(K key, V value) {
2370		if (key == null || value == null)
2371		throw new NullPointerException();
2372	<	return (V)internalPut(key, value, true);
2372	>	return (V)internalPut(key, value);
2373		}
2374
2375		/**
#	Line 1271 | Line 2383 | public class ConcurrentHashMapV8<K, V>
2383		public V putIfAbsent(K key, V value) {
2384		if (key == null || value == null)
2385		throw new NullPointerException();
2386	<	return (V)internalPut(key, value, false);
2386	>	return (V)internalPutIfAbsent(key, value);
2387		}
2388
2389		/**
#	Line 1282 | Line 2394 | public class ConcurrentHashMapV8<K, V>
2394		* @param m mappings to be stored in this map
2395		*/
2396		public void putAll(Map<? extends K, ? extends V> m) {
2397	<	if (m == null)
1286	<	throw new NullPointerException();
1287	<	/*
1288	<	* If uninitialized, try to preallocate big enough table
1289	<	*/
1290	<	if (table == null) {
1291	<	int size = m.size();
1292	<	int n = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1293	<	tableSizeFor(size + (size >>> 1) + 1);
1294	<	int sc = sizeCtl;
1295	<	if (n < sc)
1296	<	n = sc;
1297	<	if (sc >= 0 &&
1298	<	UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1299	<	try {
1300	<	if (table == null) {
1301	<	table = new Node[n];
1302	<	sc = n - (n >>> 2) - 1;
1303	<	}
1304	<	} finally {
1305	<	sizeCtl = sc;
1306	<	}
1307	<	}
1308	<	}
1309	<	for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
1310	<	Object ek = e.getKey(), ev = e.getValue();
1311	<	if (ek == null || ev == null)
1312	<	throw new NullPointerException();
1313	<	internalPut(ek, ev, true);
1314	<	}
2397	>	internalPutAll(m);
2398		}
2399
2400		/**
2401		* If the specified key is not already associated with a value,
2402	<	* computes its value using the given mappingFunction, and if
2403	<	* non-null, enters it into the map.  This is equivalent to
2404	<	*  <pre> {@code
2402	>	* computes its value using the given mappingFunction and
2403	>	* enters it into the map.  This is equivalent to
2404	>	* <pre> {@code
2405		* if (map.containsKey(key))
2406		*   return map.get(key);
2407		* value = mappingFunction.map(key);
2408	<	* if (value != null)
1326	<	*   map.put(key, value);
2408	>	* map.put(key, value);
2409		* return value;}</pre>
2410		*
2411	<	* except that the action is performed atomically.  Some attempted
2412	<	* update operations on this map by other threads may be blocked
2413	<	* while computation is in progress, so the computation should be
2414	<	* short and simple, and must not attempt to update any other
2415	<	* mappings of this Map. The most appropriate usage is to
2416	<	* construct a new object serving as an initial mapped value, or
2417	<	* memoized result, as in:
2411	>	* except that the action is performed atomically.  If the
2412	>	* function returns {@code null} (in which case a {@code
2413	>	* NullPointerException} is thrown), or the function itself throws
2414	>	* an (unchecked) exception, the exception is rethrown to its
2415	>	* caller, and no mapping is recorded.  Some attempted update
2416	>	* operations on this map by other threads may be blocked while
2417	>	* computation is in progress, so the computation should be short
2418	>	* and simple, and must not attempt to update any other mappings
2419	>	* of this Map. The most appropriate usage is to construct a new
2420	>	* object serving as an initial mapped value, or memoized result,
2421	>	* as in:
2422	>	*
2423		*  <pre> {@code
2424		* map.computeIfAbsent(key, new MappingFunction<K, V>() {
2425		*   public V map(K k) { return new Value(f(k)); }});}</pre>
#	Line 1340 | Line 2427 | public class ConcurrentHashMapV8<K, V>
2427		* @param key key with which the specified value is to be associated
2428		* @param mappingFunction the function to compute a value
2429		* @return the current (existing or computed) value associated with
2430	<	*         the specified key, or {@code null} if the computation
2431	<	*         returned {@code null}
2432	<	* @throws NullPointerException if the specified key or mappingFunction
1346	<	*         is null
2430	>	*         the specified key.
2431	>	* @throws NullPointerException if the specified key, mappingFunction,
2432	>	*         or computed value is null
2433		* @throws IllegalStateException if the computation detectably
2434		*         attempts a recursive update to this map that would
2435		*         otherwise never complete
2436		* @throws RuntimeException or Error if the mappingFunction does so,
2437		*         in which case the mapping is left unestablished
2438		*/
2439	+	@SuppressWarnings("unchecked")
2440		public V computeIfAbsent(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2441		if (key == null || mappingFunction == null)
2442		throw new NullPointerException();
2443	<	return internalCompute(key, mappingFunction, false);
2443	>	return (V)internalComputeIfAbsent(key, mappingFunction);
2444		}
2445
2446		/**
2447	<	* Computes the value associated with the given key using the given
2448	<	* mappingFunction, and if non-null, enters it into the map.  This
2449	<	* is equivalent to
2447	>	* Computes and enters a new mapping value given a key and
2448	>	* its current mapped value (or {@code null} if there is no current
2449	>	* mapping). This is equivalent to
2450		*  <pre> {@code
2451	<	* value = mappingFunction.map(key);
2452	<	* if (value != null)
1366	<	*   map.put(key, value);
1367	<	* else
1368	<	*   value = map.get(key);
1369	<	* return value;}</pre>
2451	>	*  map.put(key, remappingFunction.remap(key, map.get(key));
2452	>	* }</pre>
2453		*
2454	<	* except that the action is performed atomically.  Some attempted
2454	>	* except that the action is performed atomically.  If the
2455	>	* function returns {@code null} (in which case a {@code
2456	>	* NullPointerException} is thrown), or the function itself throws
2457	>	* an (unchecked) exception, the exception is rethrown to its
2458	>	* caller, and current mapping is left unchanged.  Some attempted
2459		* update operations on this map by other threads may be blocked
2460		* while computation is in progress, so the computation should be
2461		* short and simple, and must not attempt to update any other
2462	<	* mappings of this Map.
2462	>	* mappings of this Map. For example, to either create or
2463	>	* append new messages to a value mapping:
2464	>	*
2465	>	* <pre> {@code
2466	>	* Map<Key, String> map = ...;
2467	>	* final String msg = ...;
2468	>	* map.compute(key, new RemappingFunction<Key, String>() {
2469	>	*   public String remap(Key k, String v) {
2470	>	*    return (v == null) ? msg : v + msg;});}}</pre>
2471		*
2472		* @param key key with which the specified value is to be associated
2473	<	* @param mappingFunction the function to compute a value
2474	<	* @return the current value associated with
2475	<	*         the specified key, or {@code null} if the computation
2476	<	*         returned {@code null} and the value was not otherwise present
2477	<	* @throws NullPointerException if the specified key or mappingFunction
1383	<	*         is null
2473	>	* @param remappingFunction the function to compute a value
2474	>	* @return the new value associated with
2475	>	*         the specified key.
2476	>	* @throws NullPointerException if the specified key or remappingFunction
2477	>	*         or computed value is null
2478		* @throws IllegalStateException if the computation detectably
2479		*         attempts a recursive update to this map that would
2480		*         otherwise never complete
2481	<	* @throws RuntimeException or Error if the mappingFunction does so,
2481	>	* @throws RuntimeException or Error if the remappingFunction does so,
2482		*         in which case the mapping is unchanged
2483		*/
2484	<	public V compute(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
2485	<	if (key == null || mappingFunction == null)
2484	>	@SuppressWarnings("unchecked")
2485	>	public V compute(K key, RemappingFunction<? super K, V> remappingFunction) {
2486	>	if (key == null || remappingFunction == null)
2487		throw new NullPointerException();
2488	<	return internalCompute(key, mappingFunction, true);
2488	>	return (V)internalCompute(key, remappingFunction);
2489		}
2490
2491		/**
#	Line 1881 | Line 2976 | public class ConcurrentHashMapV8<K, V>
2976		return true;
2977		}
2978
2979	<	public final boolean removeAll(Collection c) {
2979	>	public final boolean removeAll(Collection<?> c) {
2980		boolean modified = false;
2981		for (Iterator<?> it = iter(); it.hasNext();) {
2982		if (c.contains(it.next())) {
#	Line 1931 | Line 3026 | public class ConcurrentHashMapV8<K, V>
3026		}
3027
3028		static final class Values<K,V> extends MapView<K,V>
3029	<	implements Collection<V>  {
3029	>	implements Collection<V> {
3030		Values(ConcurrentHashMapV8<K, V> map)   { super(map); }
3031		public final boolean contains(Object o) { return map.containsValue(o); }
3032
#	Line 1961 | Line 3056 | public class ConcurrentHashMapV8<K, V>
3056		}
3057		}
3058
3059	<	static final class EntrySet<K,V>  extends MapView<K,V>
3059	>	static final class EntrySet<K,V> extends MapView<K,V>
3060		implements Set<Map.Entry<K,V>> {
3061		EntrySet(ConcurrentHashMapV8<K, V> map) { super(map); }
3062
#	Line 2063 | Line 3158 | public class ConcurrentHashMapV8<K, V>
3158		K k = (K) s.readObject();
3159		V v = (V) s.readObject();
3160		if (k != null && v != null) {
3161	<	p = new Node(spread(k.hashCode()), k, v, p);
3161	>	int h = spread(k.hashCode());
3162	>	p = new Node(h, k, v, p);
3163		++size;
3164		}
3165		else
#	Line 2079 | Line 3175 | public class ConcurrentHashMapV8<K, V>
3175		n = tableSizeFor(sz + (sz >>> 1) + 1);
3176		}
3177		int sc = sizeCtl;
3178	+	boolean collide = false;
3179		if (n > sc &&
3180		UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
3181		try {
#	Line 2089 | Line 3186 | public class ConcurrentHashMapV8<K, V>
3186		while (p != null) {
3187		int j = p.hash & mask;
3188		Node next = p.next;
3189	<	p.next = tabAt(tab, j);
3189	>	Node q = p.next = tabAt(tab, j);
3190		setTabAt(tab, j, p);
3191	+	if (!collide && q != null && q.hash == p.hash)
3192	+	collide = true;
3193		p = next;
3194		}
3195		table = tab;
3196		counter.add(size);
3197	<	sc = n - (n >>> 2) - 1;
3197	>	sc = n - (n >>> 2);
3198		}
3199		} finally {
3200		sizeCtl = sc;
3201		}
3202	+	if (collide) { // rescan and convert to TreeBins
3203	+	Node[] tab = table;
3204	+	for (int i = 0; i < tab.length; ++i) {
3205	+	int c = 0;
3206	+	for (Node e = tabAt(tab, i); e != null; e = e.next) {
3207	+	if (++c > TREE_THRESHOLD &&
3208	+	(e.key instanceof Comparable)) {
3209	+	replaceWithTreeBin(tab, i, e.key);
3210	+	break;
3211	+	}
3212	+	}
3213	+	}
3214	+	}
3215		}
3216		if (!init) { // Can only happen if unsafely published.
3217		while (p != null) {
3218	<	internalPut(p.key, p.val, true);
3218	>	internalPut(p.key, p.val);
3219		p = p.next;
3220		}
3221		}
3222	+
3223		}
3224		}
3225

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