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root/jsr166/jsr166/src/jsr166y/LinkedTransferQueue.java

Comparing jsr166/src/jsr166y/LinkedTransferQueue.java (file contents):
Revision 1.29 by jsr166, Mon Jul 27 03:21:19 2009 UTC vs.
Revision 1.33 by dl, Thu Jul 30 13:30:19 2009 UTC

#	Line 14 | Line 14 | import java.util.Iterator;
14		import java.util.NoSuchElementException;
15		import java.util.concurrent.locks.LockSupport;
16		import java.util.concurrent.atomic.AtomicReference;
17	–	import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
17
18		/**
19		* An unbounded {@linkplain TransferQueue} based on linked nodes.
#	Line 115 | Line 114 | public class LinkedTransferQueue<E> exte
114		this.isData = isData;
115		}
116
117	<	@SuppressWarnings("rawtypes")
118	<	static final AtomicReferenceFieldUpdater<Node, Node>
119	<	nextUpdater = AtomicReferenceFieldUpdater.newUpdater
120	<	(Node.class, Node.class, "next");
117	>	// Unsafe mechanics
118	>
119	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
120	>	private static final long nextOffset =
121	>	objectFieldOffset(UNSAFE, "next", Node.class);
122
123		final boolean casNext(Node<E> cmp, Node<E> val) {
124	<	return nextUpdater.compareAndSet(this, cmp, val);
124	>	return UNSAFE.compareAndSwapObject(this, nextOffset, cmp, val);
125		}
126
127		final void clearNext() {
128	<	nextUpdater.lazySet(this, this);
128	>	UNSAFE.putOrderedObject(this, nextOffset, this);
129	>	}
130	>
131	>	/**
132	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
133	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
134	>	* into a jdk.
135	>	*
136	>	* @return a sun.misc.Unsafe
137	>	*/
138	>	private static sun.misc.Unsafe getUnsafe() {
139	>	try {
140	>	return sun.misc.Unsafe.getUnsafe();
141	>	} catch (SecurityException se) {
142	>	try {
143	>	return java.security.AccessController.doPrivileged
144	>	(new java.security
145	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
146	>	public sun.misc.Unsafe run() throws Exception {
147	>	java.lang.reflect.Field f = sun.misc
148	>	.Unsafe.class.getDeclaredField("theUnsafe");
149	>	f.setAccessible(true);
150	>	return (sun.misc.Unsafe) f.get(null);
151	>	}});
152	>	} catch (java.security.PrivilegedActionException e) {
153	>	throw new RuntimeException("Could not initialize intrinsics",
154	>	e.getCause());
155	>	}
156	>	}
157		}
158
159		private static final long serialVersionUID = -3375979862319811754L;
#	Line 542 | Line 570 | public class LinkedTransferQueue<E> exte
570		}
571
572		/**
573	<	* @throws NullPointerException    {@inheritDoc}
574	<	* @throwsIllegalArgumentException {@inheritDoc}
573	>	* @throws NullPointerException     {@inheritDoc}
574	>	* @throws IllegalArgumentException {@inheritDoc}
575		*/
576		public int drainTo(Collection<? super E> c) {
577		if (c == null)
#	Line 560 | Line 588 | public class LinkedTransferQueue<E> exte
588		}
589
590		/**
591	<	* @throws NullPointerException    {@inheritDoc}
592	<	* @throwsIllegalArgumentException {@inheritDoc}
591	>	* @throws NullPointerException     {@inheritDoc}
592	>	* @throws IllegalArgumentException {@inheritDoc}
593		*/
594		public int drainTo(Collection<? super E> c, int maxElements) {
595		if (c == null)
#	Line 607 | Line 635 | public class LinkedTransferQueue<E> exte
635		}
636		}
637
610	–
638		public Iterator<E> iterator() {
639		return new Itr();
640		}
#	Line 622 | Line 649 | public class LinkedTransferQueue<E> exte
649		class Itr implements Iterator<E> {
650		Node<E> next;        // node to return next
651		Node<E> pnext;       // predecessor of next
625	–	Node<E> snext;       // successor of next
652		Node<E> curr;        // last returned node, for remove()
653		Node<E> pcurr;       // predecessor of curr, for remove()
654	<	E nextItem;        // Cache of next item, once committed to in next
654	>	E nextItem;          // Cache of next item, once committed to in next
655
656		Itr() {
657	<	findNext();
657	>	advance();
658		}
659
660		/**
661	<	* Ensures next points to next valid node, or null if none.
661	>	* Moves to next valid node and returns item to return for
662	>	* next(), or null if no such.
663		*/
664	<	void findNext() {
664	>	private E advance() {
665	>	pcurr = pnext;
666	>	curr = next;
667	>	E item = nextItem;
668	>
669		for (;;) {
670	<	Node<E> pred = pnext;
671	<	Node<E> q = next;
672	<	if (pred == null || pred == q) {
642	<	pred = traversalHead();
643	<	q = pred.next;
644	<	}
645	<	if (q == null || !q.isData) {
670	>	pnext = next == null ? traversalHead() : next;
671	>	next = pnext.next;
672	>	if (next == pnext) {
673		next = null;
674	<	return;
674	>	continue;  // restart
675		}
676	<	Object x = q.get();
677	<	Node<E> s = q.next;
678	<	if (x != null && q != x && q != s) {
676	>	if (next == null)
677	>	break;
678	>	Object x = next.get();
679	>	if (x != null && x != next) {
680		nextItem = (E) x;
681	<	snext = s;
654	<	pnext = pred;
655	<	next = q;
656	<	return;
681	>	break;
682		}
658	–	pnext = q;
659	–	next = s;
683		}
684	+	return item;
685		}
686
687		public boolean hasNext() {
#	Line 665 | Line 689 | public class LinkedTransferQueue<E> exte
689		}
690
691		public E next() {
692	<	if (next == null) throw new NoSuchElementException();
693	<	pcurr = pnext;
694	<	curr = next;
671	<	pnext = next;
672	<	next = snext;
673	<	E x = nextItem;
674	<	findNext();
675	<	return x;
692	>	if (next == null)
693	>	throw new NoSuchElementException();
694	>	return advance();
695		}
696
697		public void remove() {
#	Line 742 | Line 761 | public class LinkedTransferQueue<E> exte
761		* @return the number of elements in this queue
762		*/
763		public int size() {
764	<	int count = 0;
765	<	Node<E> h = traversalHead();
766	<	for (Node<E> p = h.next; p != null && p.isData; p = p.next) {
767	<	Object x = p.get();
768	<	if (x != null && x != p) {
769	<	if (++count == Integer.MAX_VALUE) // saturated
764	>	for (;;) {
765	>	int count = 0;
766	>	Node<E> pred = traversalHead();
767	>	for (;;) {
768	>	Node<E> q = pred.next;
769	>	if (q == pred) // restart
770		break;
771	+	if (q == null || !q.isData)
772	+	return count;
773	+	Object x = q.get();
774	+	if (x != null && x != q) {
775	+	if (++count == Integer.MAX_VALUE) // saturated
776	+	return count;
777	+	}
778	+	pred = q;
779		}
780		}
754	–	return count;
781		}
782
783		public int getWaitingConsumerCount() {
784	<	int count = 0;
785	<	Node<E> h = traversalHead();
786	<	for (Node<E> p = h.next; p != null && !p.isData; p = p.next) {
787	<	if (p.get() == null) {
788	<	if (++count == Integer.MAX_VALUE)
784	>	// converse of size -- count valid non-data nodes
785	>	for (;;) {
786	>	int count = 0;
787	>	Node<E> pred = traversalHead();
788	>	for (;;) {
789	>	Node<E> q = pred.next;
790	>	if (q == pred) // restart
791		break;
792	+	if (q == null || q.isData)
793	+	return count;
794	+	Object x = q.get();
795	+	if (x == null) {
796	+	if (++count == Integer.MAX_VALUE) // saturated
797	+	return count;
798	+	}
799	+	pred = q;
800		}
801		}
766	–	return count;
767	–	}
768	–
769	–	public int remainingCapacity() {
770	–	return Integer.MAX_VALUE;
802		}
803
804		public boolean remove(Object o) {
#	Line 777 | Line 808 | public class LinkedTransferQueue<E> exte
808		Node<E> pred = traversalHead();
809		for (;;) {
810		Node<E> q = pred.next;
780	–	if (q == null || !q.isData)
781	–	return false;
811		if (q == pred) // restart
812		break;
813	+	if (q == null || !q.isData)
814	+	return false;
815		Object x = q.get();
816		if (x != null && x != q && o.equals(x) &&
817		q.compareAndSet(x, q)) {
#	Line 792 | Line 823 | public class LinkedTransferQueue<E> exte
823		}
824		}
825
826	+	public int remainingCapacity() {
827	+	return Integer.MAX_VALUE;
828	+	}
829	+
830		/**
831		* Save the state to a stream (that is, serialize it).
832		*
#	Line 842 | Line 877 | public class LinkedTransferQueue<E> exte
877
878		private static final sun.misc.Unsafe UNSAFE = getUnsafe();
879		private static final long headOffset =
880	<	objectFieldOffset("head", LinkedTransferQueue.class);
880	>	objectFieldOffset(UNSAFE, "head", LinkedTransferQueue.class);
881		private static final long tailOffset =
882	<	objectFieldOffset("tail", LinkedTransferQueue.class);
882	>	objectFieldOffset(UNSAFE, "tail", LinkedTransferQueue.class);
883		private static final long cleanMeOffset =
884	<	objectFieldOffset("cleanMe", LinkedTransferQueue.class);
884	>	objectFieldOffset(UNSAFE, "cleanMe", LinkedTransferQueue.class);
885	>
886
887	<	private static long objectFieldOffset(String field, Class<?> klazz) {
887	>	static long objectFieldOffset(sun.misc.Unsafe UNSAFE,
888	>	String field, Class<?> klazz) {
889		try {
890		return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
891		} catch (NoSuchFieldException e) {

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