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root/jsr166/jsr166/src/main/java/util/concurrent/Exchanger.java

Comparing jsr166/src/main/java/util/concurrent/Exchanger.java (file contents):
Revision 1.40 by jsr166, Mon Feb 13 08:12:10 2006 UTC vs.
Revision 1.41 by dl, Mon Feb 13 12:38:45 2006 UTC

#	Line 288 | Line 288 | public class Exchanger<V> {
288		/**
289		* The maximum slot index being used.  The value sometimes
290		* increases when a thread experiences too many CAS contentions,
291	<	* and sometimes decreases when a backoff wait elapses.  Changes
291	>	* and sometimes decreases when a spin-wait elapses.  Changes
292		* are performed only via compareAndSet, to avoid stale values
293		* when a thread happens to stall right before setting.
294		*/
#	Line 382 | Line 382 | public class Exchanger<V> {
382
383		/**
384		* Creates a new slot at given index.  Called only when the slot
385	<	* appears to be null.  Relies on double-check using builtin locks,
386	<	* since they rarely contend.
385	>	* appears to be null.  Relies on double-check using builtin
386	>	* locks, since they rarely contend. This in turn relies on the
387	>	* arena array being declared volatile.
388		*
389		* @param index the index to add slot at
390		*/
#	Line 398 | Line 399 | public class Exchanger<V> {
399		}
400
401		/**
402	<	* Try to cancel a wait for the given node waiting in the given
402	>	* Trie to cancel a wait for the given node waiting in the given
403		* slot, if so, helping clear the node from its slot to avoid
404		* garbage retention.
405		*
#	Line 409 | Line 410 | public class Exchanger<V> {
410		private static boolean tryCancel(Node node, Slot slot) {
411		if (!node.compareAndSet(null, CANCEL))
412		return false;
413	<	if (slot.get() == node)
413	>	if (slot.get() == node) // pre-check to minimize contention
414		slot.compareAndSet(node, null);
415		return true;
416		}

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