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Comparing jsr166/src/jsr166e/ConcurrentHashMapV8.java (file contents):
Revision 1.37 by dl, Sun Mar 4 20:34:27 2012 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 22 | Line 24 | 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 148 | Line 151 | public class ConcurrentHashMapV8<K, V>
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	<	* sprawling variants of put-related operations).
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, the list has only zero or one Node).  Table
161	<	* accesses require volatile/atomic reads, writes, and CASes.
162	<	* Because there is no other way to arrange this without adding
163	<	* further indirections, we use intrinsics (sun.misc.Unsafe)
164	<	* operations.  The lists of nodes within bins are always
165	<	* accurately traversable under volatile reads, so long as lookups
166	<	* check hash code and non-nullness of value before checking key
167	<	* 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
#	Line 171 | Line 176 | public class ConcurrentHashMapV8<K, V>
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 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
#	Line 202 | Line 207 | public class ConcurrentHashMapV8<K, V>
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
208	<	* 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"
233	<	* performs hashCode randomization that improves the likelihood
234	<	* that these assumptions hold unless users define exactly the
235	<	* same value for too many hashCodes.
232	>	* elements is roughly 1 / (8 * #elements) under random hashes.
233	>	*
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 an occupancy
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 246 | 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 348 | 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.
#	Line 387 | 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		/**
#	Line 399 | Line 460 | public class ConcurrentHashMapV8<K, V>
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 479 | 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
486	<	* elements of in-progress next table while resizing.  Uses are
487	<	* null checked by callers, and implicitly bounds-checked, relying
488	<	* on the invariants that tab arrays have non-zero size, and all
489	<	* indices are masked with (tab.length - 1) which is never
490	<	* negative and always less than length. Note that, to be correct
491	<	* wrt arbitrary concurrency errors by users, bounds checks must
492	<	* operate on local variables, which accounts for some odd-looking
493	<	* 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	<	// Despite two multiplies, this is often faster than others
1035	<	// with comparable bit-spread properties.
1036	<	h ^= h >>> 16;
1037	<	h *= 0x85ebca6b;
1038	<	h ^= h >>> 13;
1039	<	h *= 0xc2b2ae35;
1040	<	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 554 | 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) {
#	Line 618 | Line 1178 | public class ConcurrentHashMapV8<K, V>
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. Lock and validate; if valid, scan and add or update
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.
#	Line 639 | Line 1200 | public class ConcurrentHashMapV8<K, V>
1200		/** Implementation for put */
1201		private final Object internalPut(Object k, Object v) {
1202		int h = spread(k.hashCode());
1203	<	boolean checkSize = false;
1203	>	int count = 0;
1204		for (Node[] tab = table;;) {
1205	<	int i; Node f; int fh;
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	<	tab = (Node[])f.key;
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;
659	–	boolean validated = false;
1244		try {                        // needed in case equals() throws
1245		if (tabAt(tab, i) == f) {
1246	<	validated = true;    // retry if 1st already deleted
1247	<	for (Node e = 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 &&
#	Line 672 | Line 1256 | public class ConcurrentHashMapV8<K, V>
1256		Node last = e;
1257		if ((e = e.next) == null) {
1258		last.next = new Node(h, k, v, null);
1259	<	if (last != f || tab.length <= 64)
1260	<	checkSize = true;
1259	>	if (count >= TREE_THRESHOLD)
1260	>	replaceWithTreeBin(tab, i, k);
1261		break;
1262		}
1263		}
#	Line 684 | Line 1268 | public class ConcurrentHashMapV8<K, V>
1268		synchronized (f) { f.notifyAll(); };
1269		}
1270		}
1271	<	if (validated) {
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 (checkSize)
1281	>	if (count > 1)
1282		checkForResize();
1283		return null;
1284		}
#	Line 700 | Line 1286 | public class ConcurrentHashMapV8<K, V>
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)
#	Line 708 | Line 1295 | public class ConcurrentHashMapV8<K, V>
1295		if (casTabAt(tab, i, null, new Node(h, k, v, null)))
1296		break;
1297		}
1298	<	else if ((fh = f.hash) == MOVED)
1299	<	tab = (Node[])f.key;
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;
#	Line 733 | Line 1342 | public class ConcurrentHashMapV8<K, V>
1342		}
1343		else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1344		Object oldVal = null;
736	–	boolean validated = false;
1345		try {
1346		if (tabAt(tab, i) == f) {
1347	<	validated = true;
1348	<	for (Node e = 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 &&
#	Line 748 | Line 1356 | public class ConcurrentHashMapV8<K, V>
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		}
#	Line 758 | Line 1368 | public class ConcurrentHashMapV8<K, V>
1368		synchronized (f) { f.notifyAll(); };
1369		}
1370		}
1371	<	if (validated) {
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
#	Line 775 | Line 1389 | public class ConcurrentHashMapV8<K, V>
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);
784	–	boolean validated = false;
1399		if (casTabAt(tab, i, null, node)) {
1400	<	validated = true;
1400	>	count = 1;
1401		try {
1402		if ((val = mf.map(k)) != null)
1403		node.val = val;
#	Line 796 | Line 1410 | public class ConcurrentHashMapV8<K, V>
1410		}
1411		}
1412		}
1413	<	if (validated)
1413	>	if (count != 0)
1414		break;
1415		}
1416	<	else if ((fh = f.hash) == MOVED)
1417	<	tab = (Node[])f.key;
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;
#	Line 823 | Line 1464 | public class ConcurrentHashMapV8<K, V>
1464		f.tryAwaitLock(tab, i);
1465		}
1466		else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) {
1467	<	boolean validated = false;
1467	>	boolean added = false;
1468		try {
1469		if (tabAt(tab, i) == f) {
1470	<	validated = true;
1471	<	for (Node e = 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 &&
#	Line 837 | Line 1478 | public class ConcurrentHashMapV8<K, V>
1478		}
1479		Node last = e;
1480		if ((e = e.next) == null) {
1481	<	if ((val = mf.map(k)) != 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		}
#	Line 849 | Line 1494 | public class ConcurrentHashMapV8<K, V>
1494		synchronized (f) { f.notifyAll(); };
1495		}
1496		}
1497	<	if (validated)
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
#	Line 867 | Line 1519 | public class ConcurrentHashMapV8<K, V>
1519		int h = spread(k.hashCode());
1520		Object val = null;
1521		boolean added = false;
1522	<	boolean checkSize = false;
1522	>	int count = 0;
1523		for (Node[] tab = table;;) {
1524	<	Node f; int i, fh;
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);
877	–	boolean validated = false;
1529		if (casTabAt(tab, i, null, node)) {
879	–	validated = true;
1530		try {
1531	+	count = 1;
1532		if ((val = mf.remap(k, null)) != null) {
1533		node.val = val;
1534		added = true;
#	Line 891 | Line 1542 | public class ConcurrentHashMapV8<K, V>
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;
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) {
1577		checkForResize();
1578		f.tryAwaitLock(tab, i);
1579		}
1580		else if (f.casHash(fh, fh | LOCKED)) {
904	–	boolean validated = false;
1581		try {
1582		if (tabAt(tab, i) == f) {
1583	<	validated = true;
1584	<	for (Node e = f;;) {
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 &&
#	Line 920 | Line 1596 | public class ConcurrentHashMapV8<K, V>
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 933 | Line 1609 | public class ConcurrentHashMapV8<K, V>
1609		synchronized (f) { f.notifyAll(); };
1610		}
1611		}
1612	<	if (validated)
1612	>	if (count != 0) {
1613	>	if (tab.length <= 64)
1614	>	count = 2;
1615		break;
1616	+	}
1617		}
1618		}
1619		if (val == null)
1620		throw new NullPointerException();
1621		if (added) {
1622		counter.add(1L);
1623	<	if (checkSize)
1623	>	if (count > 1)
1624		checkForResize();
1625		}
1626		return val;
#	Line 962 | Line 1641 | public class ConcurrentHashMapV8<K, V>
1641		}
1642		int h = spread(k.hashCode());
1643		for (Node[] tab = table;;) {
1644	<	int i; Node f; int fh;
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){
#	Line 971 | Line 1650 | public class ConcurrentHashMapV8<K, V>
1650		break;
1651		}
1652		}
1653	<	else if ((fh = f.hash) == MOVED)
1654	<	tab = (Node[])f.key;
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	>	else
1676	>	tab = (Node[])fk;
1677	>	}
1678		else if ((fh & LOCKED) != 0) {
1679		counter.add(delta);
1680		delta = 0L;
#	Line 980 | Line 1682 | public class ConcurrentHashMapV8<K, V>
1682		f.tryAwaitLock(tab, i);
1683		}
1684		else if (f.casHash(fh, fh | LOCKED)) {
1685	<	boolean validated = false;
984	<	boolean tooLong = false;
1685	>	int count = 0;
1686		try {
1687		if (tabAt(tab, i) == f) {
1688	<	validated = true;
1689	<	for (Node e = 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 &&
#	Line 997 | Line 1698 | public class ConcurrentHashMapV8<K, V>
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		}
1002	–	tooLong = true;
1705		}
1706		}
1707		} finally {
#	Line 1008 | Line 1710 | public class ConcurrentHashMapV8<K, V>
1710		synchronized (f) { f.notifyAll(); };
1711		}
1712		}
1713	<	if (validated) {
1714	<	if (tooLong) {
1713	>	if (count != 0) {
1714	>	if (count > 1) {
1715		counter.add(delta);
1716		delta = 0L;
1717		checkForResize();
#	Line 1165 | Line 1867 | public class ConcurrentHashMapV8<K, V>
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;
1174	<	Node lo = null, hi = null;
1175	<	int runBit = e.hash & n;
1176	<	for (Node p = e.next; p != null; p = p.next) {
1177	<	int b = p.hash & n;
1178	<	if (b != runBit) {
1179	<	runBit = b;
1180	<	lastRun = p;
1181	<	}
1182	<	}
1183	<	if (runBit == 0)
1184	<	lo = lastRun;
1185	<	else
1186	<	hi = lastRun;
1187	<	for (Node p = e; p != lastRun; p = p.next) {
1188	<	int ph = p.hash & HASH_BITS;
1189	<	Object pk = p.key, pv = p.val;
1190	<	if ((ph & n) == 0)
1191	<	lo = new Node(ph, pk, pv, lo);
1192	<	else
1193	<	hi = new Node(ph, pk, pv, hi);
1194	<	}
1195	<	setTabAt(nextTab, i, lo);
1196	<	setTabAt(nextTab, i + n, hi);
1894	>	splitBin(nextTab, i, f);
1895		setTabAt(tab, i, fwd);
1896		}
1897		} finally {
#	Line 1239 | Line 1937 | public class ConcurrentHashMapV8<K, V>
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		*/
#	Line 1247 | Line 2015 | public class ConcurrentHashMapV8<K, V>
2015		int i = 0;
2016		Node[] tab = table;
2017		while (tab != null && i < tab.length) {
2018	<	int fh;
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	<	tab = (Node[])f.key;
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)) {
1262	–	boolean validated = false;
2049		try {
2050		if (tabAt(tab, i) == f) {
1265	–	validated = true;
2051		for (Node e = f; e != null; e = e.next) {
2052	<	if (e.val != null) { // currently always true
2053	<	e.val = null;
1269	<	--delta;
1270	<	}
2052	>	e.val = null;
2053	>	--delta;
2054		}
2055		setTabAt(tab, i, null);
2056	+	++i;
2057		}
2058		} finally {
2059		if (!f.casHash(fh | LOCKED, fh)) {
#	Line 1277 | Line 2061 | public class ConcurrentHashMapV8<K, V>
2061		synchronized (f) { f.notifyAll(); };
2062		}
2063		}
1280	–	if (validated)
1281	–	++i;
2064		}
2065		}
2066		if (delta != 0)
2067		counter.add(delta);
2068		}
2069
1288	–
2070		/* ----------------Table Traversal -------------- */
2071
2072		/**
#	Line 1364 | 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 2372 | 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 2388 | 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 2398 | 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;
#	Line 2409 | Line 3199 | public class ConcurrentHashMapV8<K, V>
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) {
#	Line 2416 | Line 3219 | public class ConcurrentHashMapV8<K, V>
3219		p = p.next;
3220		}
3221		}
3222	+
3223		}
3224		}
3225

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