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Comparing jsr166/src/jsr166e/ConcurrentHashMapV8.java (file contents):
Revision 1.25 by dl, Mon Sep 19 12:31:07 2011 UTC vs.
Revision 1.37 by dl, Sun Mar 4 20:34:27 2012 UTC

#	Line 20 | Line 20 | import java.util.Enumeration;
20		import java.util.ConcurrentModificationException;
21		import java.util.NoSuchElementException;
22		import java.util.concurrent.ConcurrentMap;
23	+	import java.util.concurrent.ThreadLocalRandom;
24		import java.util.concurrent.locks.LockSupport;
25		import java.io.Serializable;
26
#	Line 71 | Line 72 | import java.io.Serializable;
72		* versions of this class, constructors may optionally specify an
73		* expected {@code concurrencyLevel} as an additional hint for
74		* internal sizing.  Note that using many keys with exactly the same
75	<	* {@code hashCode{}} is a sure way to slow down performance of any
75	>	* {@code hashCode()} is a sure way to slow down performance of any
76		* hash table.
77		*
78		* <p>This class and its views and iterators implement all of the
#	Line 98 | Line 99 | public class ConcurrentHashMapV8<K, V>
99		private static final long serialVersionUID = 7249069246763182397L;
100
101		/**
102	<	* A function computing a mapping from the given key to a value,
103	<	* or {@code null} if there is no mapping. This is a place-holder
103	<	* for an upcoming JDK8 interface.
102	>	* A function computing a mapping from the given key to a value.
103	>	* This is a place-holder for an upcoming JDK8 interface.
104		*/
105		public static interface MappingFunction<K, V> {
106		/**
107	<	* 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.
107	>	* Returns a non-null value for the given key.
108		*
109		* @param key the (non-null) key
110	<	* @return a value, or null if none
110	>	* @return a non-null value
111		*/
112		V map(K key);
113		}
114
115	+	/**
116	+	* A function computing a new mapping given a key and its current
117	+	* mapped value (or {@code null} if there is no current
118	+	* mapping). This is a place-holder for an upcoming JDK8
119	+	* interface.
120	+	*/
121	+	public static interface RemappingFunction<K, V> {
122	+	/**
123	+	* Returns a new value given a key and its current value.
124	+	*
125	+	* @param key the (non-null) key
126	+	* @param value the current value, or null if there is no mapping
127	+	* @return a non-null value
128	+	*/
129	+	V remap(K key, V value);
130	+	}
131	+
132		/*
133		* Overview:
134		*
#	Line 134 | Line 145 | public class ConcurrentHashMapV8<K, V>
145		* work off Object types. And similarly, so do the internal
146		* methods of auxiliary iterator and view classes.  All public
147		* generic typed methods relay in/out of these internal methods,
148	<	* supplying null-checks and casts as needed.
148	>	* supplying null-checks and casts as needed. This also allows
149	>	* many of the public methods to be factored into a smaller number
150	>	* of internal methods (although sadly not so for the five
151	>	* sprawling variants of put-related operations).
152		*
153		* The table is lazily initialized to a power-of-two size upon the
154		* first insertion.  Each bin in the table contains a list of
155	<	* Nodes (most often, zero or one Node).  Table accesses require
156	<	* volatile/atomic reads, writes, and CASes.  Because there is no
157	<	* other way to arrange this without adding further indirections,
158	<	* we use intrinsics (sun.misc.Unsafe) operations.  The lists of
159	<	* nodes within bins are always accurately traversable under
160	<	* volatile reads, so long as lookups check hash code and
161	<	* non-nullness of value before checking key equality.
155	>	* Nodes (most often, the list has only zero or one Node).  Table
156	>	* accesses require volatile/atomic reads, writes, and CASes.
157	>	* Because there is no other way to arrange this without adding
158	>	* further indirections, we use intrinsics (sun.misc.Unsafe)
159	>	* operations.  The lists of nodes within bins are always
160	>	* accurately traversable under volatile reads, so long as lookups
161	>	* check hash code and non-nullness of value before checking key
162	>	* equality.
163		*
164		* We use the top two bits of Node hash fields for control
165		* purposes -- they are available anyway because of addressing
166		* constraints.  As explained further below, these top bits are
167	<	* usd as follows:
167	>	* used as follows:
168		*  00 - Normal
169		*  01 - Locked
170		*  11 - Locked and may have a thread waiting for lock
#	Line 158 | Line 173 | public class ConcurrentHashMapV8<K, V>
173		* The lower 30 bits of each Node's hash field contain a
174		* transformation (for better randomization -- method "spread") of
175		* the key's hash code, except for forwarding nodes, for which the
176	<	* lower bits are zero (and so always have hash field == "MOVED").
176	>	* lower bits are zero (and so always have hash field == MOVED).
177		*
178	<	* Insertion (via put or putIfAbsent) of the first node in an
178	>	* Insertion (via put or its variants) of the first node in an
179		* empty bin is performed by just CASing it to the bin.  This is
180		* by far the most common case for put operations.  Other update
181		* operations (insert, delete, and replace) require locks.  We do
#	Line 179 | Line 194 | public class ConcurrentHashMapV8<K, V>
194		* validate that it is still the first node after locking it, and
195		* retry if not. Because new nodes are always appended to lists,
196		* once a node is first in a bin, it remains first until deleted
197	<	* or the bin becomes invalidated.  However, operations that only
198	<	* conditionally update may inspect nodes until the point of
199	<	* update. This is a converse of sorts to the lazy locking
200	<	* technique described by Herlihy & Shavit.
197	>	* or the bin becomes invalidated (upon resizing).  However,
198	>	* operations that only conditionally update may inspect nodes
199	>	* until the point of update. This is a converse of sorts to the
200	>	* lazy locking technique described by Herlihy & Shavit.
201		*
202		* The main disadvantage of per-bin locks is that other update
203		* operations on other nodes in a bin list protected by the same
#	Line 266 | Line 281 | public class ConcurrentHashMapV8<K, V>
281		* The element count is maintained using a LongAdder, which avoids
282		* contention on updates but can encounter cache thrashing if read
283		* too frequently during concurrent access. To avoid reading so
284	<	* often, resizing is normally attempted only upon adding to a bin
285	<	* already holding two or more nodes. Under uniform hash
286	<	* distributions, the probability of this occurring at threshold
287	<	* is around 13%, meaning that only about 1 in 8 puts check
288	<	* threshold (and after resizing, many fewer do so). But this
289	<	* approximation has high variance for small table sizes, so we
290	<	* check on any collision for sizes <= 64.
284	>	* often, resizing is attempted either when a bin lock is
285	>	* contended, or upon adding to a bin already holding two or more
286	>	* nodes (checked before adding in the xIfAbsent methods, after
287	>	* adding in others). Under uniform hash distributions, the
288	>	* probability of this occurring at threshold is around 13%,
289	>	* meaning that only about 1 in 8 puts check threshold (and after
290	>	* resizing, many fewer do so). But this approximation has high
291	>	* variance for small table sizes, so we check on any collision
292	>	* for sizes <= 64. The bulk putAll operation further reduces
293	>	* contention by only committing count updates upon these size
294	>	* checks.
295		*
296		* Maintaining API and serialization compatibility with previous
297		* versions of this class introduces several oddities. Mainly: We
#	Line 333 | Line 352 | public class ConcurrentHashMapV8<K, V>
352		* Encodings for special uses of Node hash fields. See above for
353		* explanation.
354		*/
355	<	static final int MOVED     = 0x80000000; // hash field for fowarding nodes
355	>	static final int MOVED     = 0x80000000; // hash field for forwarding nodes
356		static final int LOCKED    = 0x40000000; // set/tested only as a bit
357		static final int WAITING   = 0xc0000000; // both bits set/tested together
358		static final int HASH_BITS = 0x3fffffff; // usable bits of normal node hash
#	Line 373 | Line 392 | public class ConcurrentHashMapV8<K, V>
392		/**
393		* Key-value entry. Note that this is never exported out as a
394		* user-visible Map.Entry (see WriteThroughEntry and SnapshotEntry
395	<	* below). Nodes with a negative hash field are special, and do
395	>	* below). Nodes with a hash field of MOVED are special, and do
396		* not contain user keys or values.  Otherwise, keys are never
397		* null, and null val fields indicate that a node is in the
398		* process of being deleted or created. For purposes of read-only
#	Line 417 | Line 436 | public class ConcurrentHashMapV8<K, V>
436		*/
437		final void tryAwaitLock(Node[] tab, int i) {
438		if (tab != null && i >= 0 && i < tab.length) { // bounds check
439	+	int r = ThreadLocalRandom.current().nextInt(); // randomize spins
440		int spins = MAX_SPINS, h;
441		while (tabAt(tab, i) == this && ((h = hash) & LOCKED) != 0) {
442		if (spins >= 0) {
443	<	if (--spins == MAX_SPINS >>> 1)
444	<	Thread.yield();  // heuristically yield mid-way
443	>	r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift
444	>	if (r >= 0 && --spins == 0)
445	>	Thread.yield();  // yield before block
446		}
447		else if (casHash(h, h | WAITING)) {
448	<	synchronized(this) {
448	>	synchronized (this) {
449		if (tabAt(tab, i) == this &&
450		(hash & WAITING) == WAITING) {
451		try {
#	Line 496 | Line 517 | public class ConcurrentHashMapV8<K, V>
517		*/
518		private static final int spread(int h) {
519		// Apply base step of MurmurHash; see http://code.google.com/p/smhasher/
520	+	// Despite two multiplies, this is often faster than others
521	+	// with comparable bit-spread properties.
522		h ^= h >>> 16;
523		h *= 0x85ebca6b;
524		h ^= h >>> 13;
#	Line 522 | Line 545 | public class ConcurrentHashMapV8<K, V>
545		return null;
546		}
547
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	–
548		/**
549		* Implementation for the four public remove/replace methods:
550		* Replaces node value with v, conditional upon match of cv if
#	Line 605 | Line 562 | public class ConcurrentHashMapV8<K, V>
562		tab = (Node[])f.key;
563		else if ((fh & HASH_BITS) != h && f.next == null) // precheck
564		break;                          // rules out possible existence
565	<	else if ((fh & LOCKED) != 0)
565	>	else if ((fh & LOCKED) != 0) {
566	>	checkForResize();               // try resizing if can't get lock
567		f.tryAwaitLock(tab, i);
568	+	}
569		else if (f.casHash(fh, fh | LOCKED)) {
570		boolean validated = false;
571		boolean deleted = false;
#	Line 639 | Line 598 | public class ConcurrentHashMapV8<K, V>
598		} finally {
599		if (!f.casHash(fh | LOCKED, fh)) {
600		f.hash = fh;
601	<	synchronized(f) { f.notifyAll(); };
601	>	synchronized (f) { f.notifyAll(); };
602		}
603		}
604		if (validated) {
605		if (deleted)
606	<	counter.decrement();
606	>	counter.add(-1L);
607		break;
608		}
609		}
#	Line 652 | Line 611 | public class ConcurrentHashMapV8<K, V>
611		return oldVal;
612		}
613
614	<	/** Implementation for computeIfAbsent and compute. Like put, but messier. */
615	<	// Todo: Somehow reinstate non-termination check
614	>	/*
615	>	* Internal versions of the five insertion methods, each a
616	>	* little more complicated than the last. All have
617	>	* the same basic structure as the first (internalPut):
618	>	*  1. If table uninitialized, create
619	>	*  2. If bin empty, try to CAS new node
620	>	*  3. If bin stale, use new table
621	>	*  4. Lock and validate; if valid, scan and add or update
622	>	*
623	>	* The others interweave other checks and/or alternative actions:
624	>	*  * Plain put checks for and performs resize after insertion.
625	>	*  * putIfAbsent prescans for mapping without lock (and fails to add
626	>	*    if present), which also makes pre-emptive resize checks worthwhile.
627	>	*  * computeIfAbsent extends form used in putIfAbsent with additional
628	>	*    mechanics to deal with, calls, potential exceptions and null
629	>	*    returns from function call.
630	>	*  * compute uses the same function-call mechanics, but without
631	>	*    the prescans
632	>	*  * putAll attempts to pre-allocate enough table space
633	>	*    and more lazily performs count updates and checks.
634	>	*
635	>	* Someday when details settle down a bit more, it might be worth
636	>	* some factoring to reduce sprawl.
637	>	*/
638	>
639	>	/** Implementation for put */
640	>	private final Object internalPut(Object k, Object v) {
641	>	int h = spread(k.hashCode());
642	>	boolean checkSize = false;
643	>	for (Node[] tab = table;;) {
644	>	int i; Node f; int fh;
645	>	if (tab == null)
646	>	tab = initTable();
647	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
648	>	if (casTabAt(tab, i, null, new Node(h, k, v, null)))
649	>	break;                   // no lock when adding to empty bin
650	>	}
651	>	else if ((fh = f.hash) == MOVED)
652	>	tab = (Node[])f.key;
653	>	else if ((fh & LOCKED) != 0) {
654	>	checkForResize();
655	>	f.tryAwaitLock(tab, i);
656	>	}
657	>	else if (f.casHash(fh, fh | LOCKED)) {
658	>	Object oldVal = null;
659	>	boolean validated = false;
660	>	try {                        // needed in case equals() throws
661	>	if (tabAt(tab, i) == f) {
662	>	validated = true;    // retry if 1st already deleted
663	>	for (Node e = f;;) {
664	>	Object ek, ev;
665	>	if ((e.hash & HASH_BITS) == h &&
666	>	(ev = e.val) != null &&
667	>	((ek = e.key) == k || k.equals(ek))) {
668	>	oldVal = ev;
669	>	e.val = v;
670	>	break;
671	>	}
672	>	Node last = e;
673	>	if ((e = e.next) == null) {
674	>	last.next = new Node(h, k, v, null);
675	>	if (last != f || tab.length <= 64)
676	>	checkSize = true;
677	>	break;
678	>	}
679	>	}
680	>	}
681	>	} finally {                  // unlock and signal if needed
682	>	if (!f.casHash(fh | LOCKED, fh)) {
683	>	f.hash = fh;
684	>	synchronized (f) { f.notifyAll(); };
685	>	}
686	>	}
687	>	if (validated) {
688	>	if (oldVal != null)
689	>	return oldVal;
690	>	break;
691	>	}
692	>	}
693	>	}
694	>	counter.add(1L);
695	>	if (checkSize)
696	>	checkForResize();
697	>	return null;
698	>	}
699	>
700	>	/** Implementation for putIfAbsent */
701	>	private final Object internalPutIfAbsent(Object k, Object v) {
702	>	int h = spread(k.hashCode());
703	>	for (Node[] tab = table;;) {
704	>	int i; Node f; int fh; Object fk, fv;
705	>	if (tab == null)
706	>	tab = initTable();
707	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
708	>	if (casTabAt(tab, i, null, new Node(h, k, v, null)))
709	>	break;
710	>	}
711	>	else if ((fh = f.hash) == MOVED)
712	>	tab = (Node[])f.key;
713	>	else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
714	>	((fk = f.key) == k || k.equals(fk)))
715	>	return fv;
716	>	else {
717	>	Node g = f.next;
718	>	if (g != null) { // at least 2 nodes -- search and maybe resize
719	>	for (Node e = g;;) {
720	>	Object ek, ev;
721	>	if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
722	>	((ek = e.key) == k || k.equals(ek)))
723	>	return ev;
724	>	if ((e = e.next) == null) {
725	>	checkForResize();
726	>	break;
727	>	}
728	>	}
729	>	}
730	>	if (((fh = f.hash) & LOCKED) != 0) {
731	>	checkForResize();
732	>	f.tryAwaitLock(tab, i);
733	>	}
734	>	else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
735	>	Object oldVal = null;
736	>	boolean validated = false;
737	>	try {
738	>	if (tabAt(tab, i) == f) {
739	>	validated = true;
740	>	for (Node e = f;;) {
741	>	Object ek, ev;
742	>	if ((e.hash & HASH_BITS) == h &&
743	>	(ev = e.val) != null &&
744	>	((ek = e.key) == k || k.equals(ek))) {
745	>	oldVal = ev;
746	>	break;
747	>	}
748	>	Node last = e;
749	>	if ((e = e.next) == null) {
750	>	last.next = new Node(h, k, v, null);
751	>	break;
752	>	}
753	>	}
754	>	}
755	>	} finally {
756	>	if (!f.casHash(fh | LOCKED, fh)) {
757	>	f.hash = fh;
758	>	synchronized (f) { f.notifyAll(); };
759	>	}
760	>	}
761	>	if (validated) {
762	>	if (oldVal != null)
763	>	return oldVal;
764	>	break;
765	>	}
766	>	}
767	>	}
768	>	}
769	>	counter.add(1L);
770	>	return null;
771	>	}
772	>
773	>	/** Implementation for computeIfAbsent */
774	>	private final Object internalComputeIfAbsent(K k,
775	>	MappingFunction<? super K, ?> mf) {
776	>	int h = spread(k.hashCode());
777	>	Object val = null;
778	>	for (Node[] tab = table;;) {
779	>	Node f; int i, fh; Object fk, fv;
780	>	if (tab == null)
781	>	tab = initTable();
782	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
783	>	Node node = new Node(fh = h | LOCKED, k, null, null);
784	>	boolean validated = false;
785	>	if (casTabAt(tab, i, null, node)) {
786	>	validated = true;
787	>	try {
788	>	if ((val = mf.map(k)) != null)
789	>	node.val = val;
790	>	} finally {
791	>	if (val == null)
792	>	setTabAt(tab, i, null);
793	>	if (!node.casHash(fh, h)) {
794	>	node.hash = h;
795	>	synchronized (node) { node.notifyAll(); };
796	>	}
797	>	}
798	>	}
799	>	if (validated)
800	>	break;
801	>	}
802	>	else if ((fh = f.hash) == MOVED)
803	>	tab = (Node[])f.key;
804	>	else if ((fh & HASH_BITS) == h && (fv = f.val) != null &&
805	>	((fk = f.key) == k || k.equals(fk)))
806	>	return fv;
807	>	else {
808	>	Node g = f.next;
809	>	if (g != null) {
810	>	for (Node e = g;;) {
811	>	Object ek, ev;
812	>	if ((e.hash & HASH_BITS) == h && (ev = e.val) != null &&
813	>	((ek = e.key) == k || k.equals(ek)))
814	>	return ev;
815	>	if ((e = e.next) == null) {
816	>	checkForResize();
817	>	break;
818	>	}
819	>	}
820	>	}
821	>	if (((fh = f.hash) & LOCKED) != 0) {
822	>	checkForResize();
823	>	f.tryAwaitLock(tab, i);
824	>	}
825	>	else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
826	>	boolean validated = false;
827	>	try {
828	>	if (tabAt(tab, i) == f) {
829	>	validated = true;
830	>	for (Node e = f;;) {
831	>	Object ek, ev;
832	>	if ((e.hash & HASH_BITS) == h &&
833	>	(ev = e.val) != null &&
834	>	((ek = e.key) == k || k.equals(ek))) {
835	>	val = ev;
836	>	break;
837	>	}
838	>	Node last = e;
839	>	if ((e = e.next) == null) {
840	>	if ((val = mf.map(k)) != null)
841	>	last.next = new Node(h, k, val, null);
842	>	break;
843	>	}
844	>	}
845	>	}
846	>	} finally {
847	>	if (!f.casHash(fh | LOCKED, fh)) {
848	>	f.hash = fh;
849	>	synchronized (f) { f.notifyAll(); };
850	>	}
851	>	}
852	>	if (validated)
853	>	break;
854	>	}
855	>	}
856	>	}
857	>	if (val == null)
858	>	throw new NullPointerException();
859	>	counter.add(1L);
860	>	return val;
861	>	}
862	>
863	>	/** Implementation for compute */
864		@SuppressWarnings("unchecked")
865	<	private final V internalCompute(K k,
866	<	MappingFunction<? super K, ? extends V> fn,
660	<	boolean replace) {
865	>	private final Object internalCompute(K k,
866	>	RemappingFunction<? super K, V> mf) {
867		int h = spread(k.hashCode());
868	<	V val = null;
868	>	Object val = null;
869		boolean added = false;
870	<	Node[] tab = table;
871	<	outer:for (;;) {
872	<	Node f; int i, fh; Object fk, fv;
870	>	boolean checkSize = false;
871	>	for (Node[] tab = table;;) {
872	>	Node f; int i, fh;
873		if (tab == null)
874		tab = initTable();
875		else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) {
#	Line 672 | Line 878 | public class ConcurrentHashMapV8<K, V>
878		if (casTabAt(tab, i, null, node)) {
879		validated = true;
880		try {
881	<	val = fn.map(k);
676	<	if (val != null) {
881	>	if ((val = mf.remap(k, null)) != null) {
882		node.val = val;
883		added = true;
884		}
#	Line 682 | Line 887 | public class ConcurrentHashMapV8<K, V>
887		setTabAt(tab, i, null);
888		if (!node.casHash(fh, h)) {
889		node.hash = h;
890	<	synchronized(node) { node.notifyAll(); };
890	>	synchronized (node) { node.notifyAll(); };
891		}
892		}
893		}
#	Line 691 | Line 896 | public class ConcurrentHashMapV8<K, V>
896		}
897		else if ((fh = f.hash) == MOVED)
898		tab = (Node[])f.key;
899	<	else if (!replace && (fh & HASH_BITS) == h && (fv = f.val) != null &&
900	<	((fk = f.key) == k || k.equals(fk))) {
696	<	if (tabAt(tab, i) == f) {
697	<	val = (V)fv;
698	<	break;
699	<	}
700	<	}
701	<	else if ((fh & LOCKED) != 0)
899	>	else if ((fh & LOCKED) != 0) {
900	>	checkForResize();
901		f.tryAwaitLock(tab, i);
902	+	}
903		else if (f.casHash(fh, fh | LOCKED)) {
904		boolean validated = false;
705	–	boolean checkSize = false;
905		try {
906		if (tabAt(tab, i) == f) {
907		validated = true;
908		for (Node e = f;;) {
909	<	Object ek, ev, v;
909	>	Object ek, ev;
910		if ((e.hash & HASH_BITS) == h &&
911		(ev = e.val) != null &&
912		((ek = e.key) == k || k.equals(ek))) {
913	<	if (replace && (v = fn.map(k)) != null)
914	<	ev = e.val = v;
915	<	val = (V)ev;
913	>	val = mf.remap(k, (V)ev);
914	>	if (val != null)
915	>	e.val = val;
916		break;
917		}
918		Node last = e;
919		if ((e = e.next) == null) {
920	<	if ((val = fn.map(k)) != null) {
920	>	if ((val = mf.remap(k, null)) != null) {
921		last.next = new Node(h, k, val, null);
922		added = true;
923		if (last != f || tab.length <= 64)
#	Line 731 | Line 930 | public class ConcurrentHashMapV8<K, V>
930		} finally {
931		if (!f.casHash(fh | LOCKED, fh)) {
932		f.hash = fh;
933	<	synchronized(f) { f.notifyAll(); };
933	>	synchronized (f) { f.notifyAll(); };
934		}
935		}
936	<	if (validated) {
738	<	int sc;
739	<	if (checkSize && tab.length < MAXIMUM_CAPACITY &&
740	<	(sc = sizeCtl) >= 0 && counter.sum() >= (long)sc)
741	<	growTable();
936	>	if (validated)
937		break;
743	–	}
938		}
939		}
940	<	if (added)
941	<	counter.increment();
940	>	if (val == null)
941	>	throw new NullPointerException();
942	>	if (added) {
943	>	counter.add(1L);
944	>	if (checkSize)
945	>	checkForResize();
946	>	}
947		return val;
948		}
949
950	<	/**
951	<	* Implementation for clear. Steps through each bin, removing all nodes.
952	<	*/
953	<	private final void internalClear() {
954	<	long delta = 0L; // negative number of deletions
955	<	int i = 0;
956	<	Node[] tab = table;
957	<	while (tab != null && i < tab.length) {
958	<	int fh;
959	<	Node f = tabAt(tab, i);
960	<	if (f == null)
961	<	++i;
962	<	else if ((fh = f.hash) == MOVED)
963	<	tab = (Node[])f.key;
964	<	else if ((fh & LOCKED) != 0)
965	<	f.tryAwaitLock(tab, i);
966	<	else if (f.casHash(fh, fh | LOCKED)) {
967	<	boolean validated = false;
968	<	try {
969	<	if (tabAt(tab, i) == f) {
970	<	validated = true;
971	<	for (Node e = f; e != null; e = e.next) {
773	<	if (e.val != null) { // currently always true
774	<	e.val = null;
775	<	--delta;
776	<	}
950	>	/** Implementation for putAll */
951	>	private final void internalPutAll(Map<?, ?> m) {
952	>	tryPresize(m.size());
953	>	long delta = 0L;     // number of uncommitted additions
954	>	boolean npe = false; // to throw exception on exit for nulls
955	>	try {                // to clean up counts on other exceptions
956	>	for (Map.Entry<?, ?> entry : m.entrySet()) {
957	>	Object k, v;
958	>	if (entry == null || (k = entry.getKey()) == null ||
959	>	(v = entry.getValue()) == null) {
960	>	npe = true;
961	>	break;
962	>	}
963	>	int h = spread(k.hashCode());
964	>	for (Node[] tab = table;;) {
965	>	int i; Node f; int fh;
966	>	if (tab == null)
967	>	tab = initTable();
968	>	else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){
969	>	if (casTabAt(tab, i, null, new Node(h, k, v, null))) {
970	>	++delta;
971	>	break;
972		}
778	–	setTabAt(tab, i, null);
973		}
974	<	} finally {
975	<	if (!f.casHash(fh | LOCKED, fh)) {
976	<	f.hash = fh;
977	<	synchronized(f) { f.notifyAll(); };
974	>	else if ((fh = f.hash) == MOVED)
975	>	tab = (Node[])f.key;
976	>	else if ((fh & LOCKED) != 0) {
977	>	counter.add(delta);
978	>	delta = 0L;
979	>	checkForResize();
980	>	f.tryAwaitLock(tab, i);
981	>	}
982	>	else if (f.casHash(fh, fh | LOCKED)) {
983	>	boolean validated = false;
984	>	boolean tooLong = false;
985	>	try {
986	>	if (tabAt(tab, i) == f) {
987	>	validated = true;
988	>	for (Node e = f;;) {
989	>	Object ek, ev;
990	>	if ((e.hash & HASH_BITS) == h &&
991	>	(ev = e.val) != null &&
992	>	((ek = e.key) == k || k.equals(ek))) {
993	>	e.val = v;
994	>	break;
995	>	}
996	>	Node last = e;
997	>	if ((e = e.next) == null) {
998	>	++delta;
999	>	last.next = new Node(h, k, v, null);
1000	>	break;
1001	>	}
1002	>	tooLong = true;
1003	>	}
1004	>	}
1005	>	} finally {
1006	>	if (!f.casHash(fh | LOCKED, fh)) {
1007	>	f.hash = fh;
1008	>	synchronized (f) { f.notifyAll(); };
1009	>	}
1010	>	}
1011	>	if (validated) {
1012	>	if (tooLong) {
1013	>	counter.add(delta);
1014	>	delta = 0L;
1015	>	checkForResize();
1016	>	}
1017	>	break;
1018	>	}
1019		}
1020		}
786	–	if (validated)
787	–	++i;
1021		}
1022	+	} finally {
1023	+	if (delta != 0)
1024	+	counter.add(delta);
1025		}
1026	<	counter.add(delta);
1026	>	if (npe)
1027	>	throw new NullPointerException();
1028		}
1029
1030	<	/* ----------------Table Initialization and Resizing -------------- */
1030	>	/* ---------------- Table Initialization and Resizing -------------- */
1031
1032		/**
1033		* Returns a power of two table size for the given desired capacity.
#	Line 819 | Line 1056 | public class ConcurrentHashMapV8<K, V>
1056		if ((tab = table) == null) {
1057		int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
1058		tab = table = new Node[n];
1059	<	sc = n - (n >>> 2) - 1;
1059	>	sc = n - (n >>> 2);
1060		}
1061		} finally {
1062		sizeCtl = sc;
#	Line 831 | Line 1068 | public class ConcurrentHashMapV8<K, V>
1068		}
1069
1070		/**
1071	<	* If not already resizing, creates next table and transfers bins.
1072	<	* Rechecks occupancy after a transfer to see if another resize is
1073	<	* already needed because resizings are lagging additions.
1074	<	*/
1075	<	private final void growTable() {
1076	<	int sc = sizeCtl;
1077	<	if (sc >= 0 && UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1071	>	* If table is too small and not already resizing, creates next
1072	>	* table and transfers bins.  Rechecks occupancy after a transfer
1073	>	* to see if another resize is already needed because resizings
1074	>	* are lagging additions.
1075	>	*/
1076	>	private final void checkForResize() {
1077	>	Node[] tab; int n, sc;
1078	>	while ((tab = table) != null &&
1079	>	(n = tab.length) < MAXIMUM_CAPACITY &&
1080	>	(sc = sizeCtl) >= 0 && counter.sum() >= (long)sc &&
1081	>	UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1082		try {
1083	<	Node[] tab; int n;
843	<	while ((tab = table) != null &&
844	<	(n = tab.length) > 0 && n < MAXIMUM_CAPACITY &&
845	<	counter.sum() >= (long)sc) {
1083	>	if (tab == table) {
1084		table = rebuild(tab);
1085	<	sc = (n << 1) - (n >>> 1) - 1;
1085	>	sc = (n << 1) - (n >>> 1);
1086		}
1087		} finally {
1088		sizeCtl = sc;
#	Line 852 | Line 1090 | public class ConcurrentHashMapV8<K, V>
1090		}
1091		}
1092
1093	+	/**
1094	+	* Tries to presize table to accommodate the given number of elements.
1095	+	*
1096	+	* @param size number of elements (doesn't need to be perfectly accurate)
1097	+	*/
1098	+	private final void tryPresize(int size) {
1099	+	int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY :
1100	+	tableSizeFor(size + (size >>> 1) + 1);
1101	+	int sc;
1102	+	while ((sc = sizeCtl) >= 0) {
1103	+	Node[] tab = table; int n;
1104	+	if (tab == null || (n = tab.length) == 0) {
1105	+	n = (sc > c) ? sc : c;
1106	+	if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1107	+	try {
1108	+	if (table == tab) {
1109	+	table = new Node[n];
1110	+	sc = n - (n >>> 2);
1111	+	}
1112	+	} finally {
1113	+	sizeCtl = sc;
1114	+	}
1115	+	}
1116	+	}
1117	+	else if (c <= sc || n >= MAXIMUM_CAPACITY)
1118	+	break;
1119	+	else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) {
1120	+	try {
1121	+	if (table == tab) {
1122	+	table = rebuild(tab);
1123	+	sc = (n << 1) - (n >>> 1);
1124	+	}
1125	+	} finally {
1126	+	sizeCtl = sc;
1127	+	}
1128	+	}
1129	+	}
1130	+	}
1131	+
1132		/*
1133		* Moves and/or copies the nodes in each bin to new table. See
1134		* above for explanation.
#	Line 876 | Line 1153 | public class ConcurrentHashMapV8<K, V>
1153		continue;
1154		}
1155		else {             // transiently use a locked forwarding node
1156	<	Node g =  new Node(MOVED|LOCKED, nextTab, null, null);
1156	>	Node g = new Node(MOVED|LOCKED, nextTab, null, null);
1157		if (!casTabAt(tab, i, f, g))
1158		continue;
1159		setTabAt(nextTab, i, null);
#	Line 884 | Line 1161 | public class ConcurrentHashMapV8<K, V>
1161		setTabAt(tab, i, fwd);
1162		if (!g.casHash(MOVED|LOCKED, MOVED)) {
1163		g.hash = MOVED;
1164	<	synchronized(g) { g.notifyAll(); }
1164	>	synchronized (g) { g.notifyAll(); }
1165		}
1166		}
1167		}
#	Line 922 | Line 1199 | public class ConcurrentHashMapV8<K, V>
1199		} finally {
1200		if (!f.casHash(fh | LOCKED, fh)) {
1201		f.hash = fh;
1202	<	synchronized(f) { f.notifyAll(); };
1202	>	synchronized (f) { f.notifyAll(); };
1203		}
1204		}
1205		if (!validated)
#	Line 961 | Line 1238 | public class ConcurrentHashMapV8<K, V>
1238		}
1239		}
1240
1241	+	/**
1242	+	* Implementation for clear. Steps through each bin, removing all
1243	+	* nodes.
1244	+	*/
1245	+	private final void internalClear() {
1246	+	long delta = 0L; // negative number of deletions
1247	+	int i = 0;
1248	+	Node[] tab = table;
1249	+	while (tab != null && i < tab.length) {
1250	+	int fh;
1251	+	Node f = tabAt(tab, i);
1252	+	if (f == null)
1253	+	++i;
1254	+	else if ((fh = f.hash) == MOVED)
1255	+	tab = (Node[])f.key;
1256	+	else if ((fh & LOCKED) != 0) {
1257	+	counter.add(delta); // opportunistically update count
1258	+	delta = 0L;
1259	+	f.tryAwaitLock(tab, i);
1260	+	}
1261	+	else if (f.casHash(fh, fh | LOCKED)) {
1262	+	boolean validated = false;
1263	+	try {
1264	+	if (tabAt(tab, i) == f) {
1265	+	validated = true;
1266	+	for (Node e = f; e != null; e = e.next) {
1267	+	if (e.val != null) { // currently always true
1268	+	e.val = null;
1269	+	--delta;
1270	+	}
1271	+	}
1272	+	setTabAt(tab, i, null);
1273	+	}
1274	+	} finally {
1275	+	if (!f.casHash(fh | LOCKED, fh)) {
1276	+	f.hash = fh;
1277	+	synchronized (f) { f.notifyAll(); };
1278	+	}
1279	+	}
1280	+	if (validated)
1281	+	++i;
1282	+	}
1283	+	}
1284	+	if (delta != 0)
1285	+	counter.add(delta);
1286	+	}
1287	+
1288	+
1289		/* ----------------Table Traversal -------------- */
1290
1291		/**
#	Line 969 | Line 1294 | public class ConcurrentHashMapV8<K, V>
1294		*
1295		* At each step, the iterator snapshots the key ("nextKey") and
1296		* value ("nextVal") of a valid node (i.e., one that, at point of
1297	<	* snapshot, has a nonnull user value). Because val fields can
1297	>	* snapshot, has a non-null user value). Because val fields can
1298		* change (including to null, indicating deletion), field nextVal
1299		* might not be accurate at point of use, but still maintains the
1300		* weak consistency property of holding a value that was once
#	Line 982 | Line 1307 | public class ConcurrentHashMapV8<K, V>
1307		* value, or key-value pairs as return values of Iterator.next(),
1308		* and encapsulate the it.next check as hasNext();
1309		*
1310	<	* The iterator visits each valid node that was reachable upon
1311	<	* iterator construction once. It might miss some that were added
1312	<	* to a bin after the bin was visited, which is OK wrt consistency
1313	<	* guarantees. Maintaining this property in the face of possible
1314	<	* ongoing resizes requires a fair amount of bookkeeping state
1315	<	* that is difficult to optimize away amidst volatile accesses.
1316	<	* Even so, traversal maintains reasonable throughput.
1310	>	* The iterator visits once each still-valid node that was
1311	>	* reachable upon iterator construction. It might miss some that
1312	>	* were added to a bin after the bin was visited, which is OK wrt
1313	>	* consistency guarantees. Maintaining this property in the face
1314	>	* of possible ongoing resizes requires a fair amount of
1315	>	* bookkeeping state that is difficult to optimize away amidst
1316	>	* volatile accesses.  Even so, traversal maintains reasonable
1317	>	* throughput.
1318		*
1319		* Normally, iteration proceeds bin-by-bin traversing lists.
1320		* However, if the table has been resized, then all future steps
#	Line 1026 | Line 1352 | public class ConcurrentHashMapV8<K, V>
1352		this.tab = tab;
1353		baseSize = (tab == null) ? 0 : tab.length;
1354		baseLimit = (hi <= baseSize) ? hi : baseSize;
1355	<	index = baseIndex = lo;
1355	>	index = baseIndex = (lo >= 0) ? lo : 0;
1356		next = null;
1357		advance();
1358		}
#	Line 1090 | Line 1416 | public class ConcurrentHashMapV8<K, V>
1416		public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) {
1417		this.counter = new LongAdder();
1418		this.sizeCtl = DEFAULT_CAPACITY;
1419	<	putAll(m);
1419	>	internalPutAll(m);
1420		}
1421
1422		/**
#	Line 1137 | Line 1463 | public class ConcurrentHashMapV8<K, V>
1463		if (initialCapacity < concurrencyLevel)   // Use at least as many bins
1464		initialCapacity = concurrencyLevel;   // as estimated threads
1465		long size = (long)(1.0 + (long)initialCapacity / loadFactor);
1466	<	int cap =  ((size >= (long)MAXIMUM_CAPACITY) ?
1467	<	MAXIMUM_CAPACITY: tableSizeFor((int)size));
1466	>	int cap = ((size >= (long)MAXIMUM_CAPACITY) ?
1467	>	MAXIMUM_CAPACITY: tableSizeFor((int)size));
1468		this.counter = new LongAdder();
1469		this.sizeCtl = cap;
1470		}
#	Line 1257 | Line 1583 | public class ConcurrentHashMapV8<K, V>
1583		public V put(K key, V value) {
1584		if (key == null || value == null)
1585		throw new NullPointerException();
1586	<	return (V)internalPut(key, value, true);
1586	>	return (V)internalPut(key, value);
1587		}
1588
1589		/**
#	Line 1271 | Line 1597 | public class ConcurrentHashMapV8<K, V>
1597		public V putIfAbsent(K key, V value) {
1598		if (key == null || value == null)
1599		throw new NullPointerException();
1600	<	return (V)internalPut(key, value, false);
1600	>	return (V)internalPutIfAbsent(key, value);
1601		}
1602
1603		/**
#	Line 1282 | Line 1608 | public class ConcurrentHashMapV8<K, V>
1608		* @param m mappings to be stored in this map
1609		*/
1610		public void putAll(Map<? extends K, ? extends V> m) {
1611	<	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	<	}
1611	>	internalPutAll(m);
1612		}
1613
1614		/**
1615		* If the specified key is not already associated with a value,
1616	<	* computes its value using the given mappingFunction, and if
1617	<	* non-null, enters it into the map.  This is equivalent to
1618	<	*  <pre> {@code
1616	>	* computes its value using the given mappingFunction and
1617	>	* enters it into the map.  This is equivalent to
1618	>	* <pre> {@code
1619		* if (map.containsKey(key))
1620		*   return map.get(key);
1621		* value = mappingFunction.map(key);
1622	<	* if (value != null)
1326	<	*   map.put(key, value);
1622	>	* map.put(key, value);
1623		* return value;}</pre>
1624		*
1625	<	* except that the action is performed atomically.  Some attempted
1626	<	* update operations on this map by other threads may be blocked
1627	<	* while computation is in progress, so the computation should be
1628	<	* short and simple, and must not attempt to update any other
1629	<	* mappings of this Map. The most appropriate usage is to
1630	<	* construct a new object serving as an initial mapped value, or
1631	<	* memoized result, as in:
1625	>	* except that the action is performed atomically.  If the
1626	>	* function returns {@code null} (in which case a {@code
1627	>	* NullPointerException} is thrown), or the function itself throws
1628	>	* an (unchecked) exception, the exception is rethrown to its
1629	>	* caller, and no mapping is recorded.  Some attempted update
1630	>	* operations on this map by other threads may be blocked while
1631	>	* computation is in progress, so the computation should be short
1632	>	* and simple, and must not attempt to update any other mappings
1633	>	* of this Map. The most appropriate usage is to construct a new
1634	>	* object serving as an initial mapped value, or memoized result,
1635	>	* as in:
1636	>	*
1637		*  <pre> {@code
1638		* map.computeIfAbsent(key, new MappingFunction<K, V>() {
1639		*   public V map(K k) { return new Value(f(k)); }});}</pre>
#	Line 1340 | Line 1641 | public class ConcurrentHashMapV8<K, V>
1641		* @param key key with which the specified value is to be associated
1642		* @param mappingFunction the function to compute a value
1643		* @return the current (existing or computed) value associated with
1644	<	*         the specified key, or {@code null} if the computation
1645	<	*         returned {@code null}
1646	<	* @throws NullPointerException if the specified key or mappingFunction
1346	<	*         is null
1644	>	*         the specified key.
1645	>	* @throws NullPointerException if the specified key, mappingFunction,
1646	>	*         or computed value is null
1647		* @throws IllegalStateException if the computation detectably
1648		*         attempts a recursive update to this map that would
1649		*         otherwise never complete
1650		* @throws RuntimeException or Error if the mappingFunction does so,
1651		*         in which case the mapping is left unestablished
1652		*/
1653	+	@SuppressWarnings("unchecked")
1654		public V computeIfAbsent(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
1655		if (key == null || mappingFunction == null)
1656		throw new NullPointerException();
1657	<	return internalCompute(key, mappingFunction, false);
1657	>	return (V)internalComputeIfAbsent(key, mappingFunction);
1658		}
1659
1660		/**
1661	<	* Computes the value associated with the given key using the given
1662	<	* mappingFunction, and if non-null, enters it into the map.  This
1663	<	* is equivalent to
1661	>	* Computes and enters a new mapping value given a key and
1662	>	* its current mapped value (or {@code null} if there is no current
1663	>	* mapping). This is equivalent to
1664		*  <pre> {@code
1665	<	* value = mappingFunction.map(key);
1666	<	* if (value != null)
1366	<	*   map.put(key, value);
1367	<	* else
1368	<	*   value = map.get(key);
1369	<	* return value;}</pre>
1665	>	*  map.put(key, remappingFunction.remap(key, map.get(key));
1666	>	* }</pre>
1667		*
1668	<	* except that the action is performed atomically.  Some attempted
1668	>	* except that the action is performed atomically.  If the
1669	>	* function returns {@code null} (in which case a {@code
1670	>	* NullPointerException} is thrown), or the function itself throws
1671	>	* an (unchecked) exception, the exception is rethrown to its
1672	>	* caller, and current mapping is left unchanged.  Some attempted
1673		* update operations on this map by other threads may be blocked
1674		* while computation is in progress, so the computation should be
1675		* short and simple, and must not attempt to update any other
1676	<	* mappings of this Map.
1676	>	* mappings of this Map. For example, to either create or
1677	>	* append new messages to a value mapping:
1678	>	*
1679	>	* <pre> {@code
1680	>	* Map<Key, String> map = ...;
1681	>	* final String msg = ...;
1682	>	* map.compute(key, new RemappingFunction<Key, String>() {
1683	>	*   public String remap(Key k, String v) {
1684	>	*    return (v == null) ? msg : v + msg;});}}</pre>
1685		*
1686		* @param key key with which the specified value is to be associated
1687	<	* @param mappingFunction the function to compute a value
1688	<	* @return the current value associated with
1689	<	*         the specified key, or {@code null} if the computation
1690	<	*         returned {@code null} and the value was not otherwise present
1691	<	* @throws NullPointerException if the specified key or mappingFunction
1383	<	*         is null
1687	>	* @param remappingFunction the function to compute a value
1688	>	* @return the new value associated with
1689	>	*         the specified key.
1690	>	* @throws NullPointerException if the specified key or remappingFunction
1691	>	*         or computed value is null
1692		* @throws IllegalStateException if the computation detectably
1693		*         attempts a recursive update to this map that would
1694		*         otherwise never complete
1695	<	* @throws RuntimeException or Error if the mappingFunction does so,
1695	>	* @throws RuntimeException or Error if the remappingFunction does so,
1696		*         in which case the mapping is unchanged
1697		*/
1698	<	public V compute(K key, MappingFunction<? super K, ? extends V> mappingFunction) {
1699	<	if (key == null || mappingFunction == null)
1698	>	@SuppressWarnings("unchecked")
1699	>	public V compute(K key, RemappingFunction<? super K, V> remappingFunction) {
1700	>	if (key == null || remappingFunction == null)
1701		throw new NullPointerException();
1702	<	return internalCompute(key, mappingFunction, true);
1702	>	return (V)internalCompute(key, remappingFunction);
1703		}
1704
1705		/**
#	Line 1881 | Line 2190 | public class ConcurrentHashMapV8<K, V>
2190		return true;
2191		}
2192
2193	<	public final boolean removeAll(Collection c) {
2193	>	public final boolean removeAll(Collection<?> c) {
2194		boolean modified = false;
2195		for (Iterator<?> it = iter(); it.hasNext();) {
2196		if (c.contains(it.next())) {
#	Line 1931 | Line 2240 | public class ConcurrentHashMapV8<K, V>
2240		}
2241
2242		static final class Values<K,V> extends MapView<K,V>
2243	<	implements Collection<V>  {
2243	>	implements Collection<V> {
2244		Values(ConcurrentHashMapV8<K, V> map)   { super(map); }
2245		public final boolean contains(Object o) { return map.containsValue(o); }
2246
#	Line 1961 | Line 2270 | public class ConcurrentHashMapV8<K, V>
2270		}
2271		}
2272
2273	<	static final class EntrySet<K,V>  extends MapView<K,V>
2273	>	static final class EntrySet<K,V> extends MapView<K,V>
2274		implements Set<Map.Entry<K,V>> {
2275		EntrySet(ConcurrentHashMapV8<K, V> map) { super(map); }
2276
#	Line 2095 | Line 2404 | public class ConcurrentHashMapV8<K, V>
2404		}
2405		table = tab;
2406		counter.add(size);
2407	<	sc = n - (n >>> 2) - 1;
2407	>	sc = n - (n >>> 2);
2408		}
2409		} finally {
2410		sizeCtl = sc;
#	Line 2103 | Line 2412 | public class ConcurrentHashMapV8<K, V>
2412		}
2413		if (!init) { // Can only happen if unsafely published.
2414		while (p != null) {
2415	<	internalPut(p.key, p.val, true);
2415	>	internalPut(p.key, p.val);
2416		p = p.next;
2417		}
2418		}

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