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

Comparing jsr166/src/jsr166y/LinkedTransferQueue.java (file contents):
Revision 1.6 by jsr166, Fri Jul 25 18:13:15 2008 UTC vs.
Revision 1.7 by dl, Wed Sep 24 10:48:43 2008 UTC

#	Line 10 | Line 10 | import java.util.concurrent.locks.*;
10		import java.util.concurrent.atomic.*;
11		import java.util.*;
12		import java.io.*;
13	+	import sun.misc.Unsafe;
14	+	import java.lang.reflect.*;
15
16		/**
17		* An unbounded {@linkplain TransferQueue} based on linked nodes.
#	Line 131 | Line 133 | public class LinkedTransferQueue<E> exte
133		}
134
135
136	<	private final QNode dummy = new QNode(null, false);
137	<	private final PaddedAtomicReference<QNode> head =
138	<	new PaddedAtomicReference<QNode>(dummy);
139	<	private final PaddedAtomicReference<QNode> tail =
138	<	new PaddedAtomicReference<QNode>(dummy);
136	>	/** head of the queue */
137	>	private transient final PaddedAtomicReference<QNode> head;
138	>	/** tail of the queue */
139	>	private transient final PaddedAtomicReference<QNode> tail;
140
141		/**
142		* Reference to a cancelled node that might not yet have been
143		* unlinked from queue because it was the last inserted node
144		* when it cancelled.
145		*/
146	<	private final PaddedAtomicReference<QNode> cleanMe =
146	<	new PaddedAtomicReference<QNode>(null);
146	>	private transient final PaddedAtomicReference<QNode> cleanMe;
147
148		/**
149		* Tries to cas nh as new head; if successful, unlink
#	Line 370 | Line 370 | public class LinkedTransferQueue<E> exte
370		* Creates an initially empty <tt>LinkedTransferQueue</tt>.
371		*/
372		public LinkedTransferQueue() {
373	+	QNode dummy = new QNode(null, false);
374	+	head = new PaddedAtomicReference<QNode>(dummy);
375	+	tail = new PaddedAtomicReference<QNode>(dummy);
376	+	cleanMe = new PaddedAtomicReference<QNode>(null);
377		}
378
379		/**
#	Line 381 | Line 385 | public class LinkedTransferQueue<E> exte
385		*         of its elements are null
386		*/
387		public LinkedTransferQueue(Collection<? extends E> c) {
388	+	this();
389		addAll(c);
390		}
391
#	Line 678 | Line 683 | public class LinkedTransferQueue<E> exte
683		private void readObject(java.io.ObjectInputStream s)
684		throws java.io.IOException, ClassNotFoundException {
685		s.defaultReadObject();
686	+	resetHeadAndTail();
687		for (;;) {
688		E item = (E)s.readObject();
689		if (item == null)
#	Line 686 | Line 692 | public class LinkedTransferQueue<E> exte
692		offer(item);
693		}
694		}
695	+
696	+
697	+	// Support for resetting head/tail while deserializing
698	+
699	+	// Temporary Unsafe mechanics for preliminary release
700	+	private static final Unsafe _unsafe;
701	+	private static final long headOffset;
702	+	private static final long tailOffset;
703	+	private static final long cleanMeOffset;
704	+	static {
705	+	try {
706	+	if (LinkedTransferQueue.class.getClassLoader() != null) {
707	+	Field f = Unsafe.class.getDeclaredField("theUnsafe");
708	+	f.setAccessible(true);
709	+	_unsafe = (Unsafe)f.get(null);
710	+	}
711	+	else
712	+	_unsafe = Unsafe.getUnsafe();
713	+	headOffset = _unsafe.objectFieldOffset
714	+	(LinkedTransferQueue.class.getDeclaredField("head"));
715	+	tailOffset = _unsafe.objectFieldOffset
716	+	(LinkedTransferQueue.class.getDeclaredField("tail"));
717	+	cleanMeOffset = _unsafe.objectFieldOffset
718	+	(LinkedTransferQueue.class.getDeclaredField("cleanMe"));
719	+	} catch (Exception e) {
720	+	throw new RuntimeException("Could not initialize intrinsics", e);
721	+	}
722	+	}
723	+
724	+	private void resetHeadAndTail() {
725	+	QNode dummy = new QNode(null, false);
726	+	_unsafe.putObjectVolatile(this, headOffset, dummy);
727	+	_unsafe.putObjectVolatile(this, tailOffset, dummy);
728	+	_unsafe.putObjectVolatile(this, cleanMeOffset,
729	+	new PaddedAtomicReference<QNode>(null));
730	+
731	+	}
732	+
733		}

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