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root/jsr166/jsr166/src/jsr166y/Phaser.java

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.9 by jsr166, Mon Jan 5 09:11:26 2009 UTC vs.
Revision 1.16 by jsr166, Wed Jul 22 01:36:51 2009 UTC

#	Line 57 | Line 57 | import java.lang.reflect.*;
57		* effect as providing a barrier action to a CyclicBarrier.
58		*
59		* <li> Phasers may enter a <em>termination</em> state in which all
60	<	* await actions immediately return, indicating (via a negative phase
61	<	* value) that execution is complete.  Termination is triggered by
62	<	* executing the overridable {@code onAdvance} method that is invoked
63	<	* each time the barrier is about to be tripped. When a Phaser is
64	<	* controlling an action with a fixed number of iterations, it is
65	<	* often convenient to override this method to cause termination when
66	<	* the current phase number reaches a threshold. Method
67	<	* {@code forceTermination} is also available to abruptly release
68	<	* waiting threads and allow them to terminate.
60	>	* actions immediately return without updating phaser state or waiting
61	>	* for advance, and indicating (via a negative phase value) that
62	>	* execution is complete.  Termination is triggered by executing the
63	>	* overridable {@code onAdvance} method that is invoked each time the
64	>	* barrier is about to be tripped. When a Phaser is controlling an
65	>	* action with a fixed number of iterations, it is often convenient to
66	>	* override this method to cause termination when the current phase
67	>	* number reaches a threshold. Method {@code forceTermination} is also
68	>	* available to abruptly release waiting threads and allow them to
69	>	* terminate.
70		*
71		* <li> Phasers may be tiered to reduce contention. Phasers with large
72		* numbers of parties that would otherwise experience heavy
#	Line 81 | Line 82 | import java.lang.reflect.*;
82		* within handlers of those exceptions, often after invoking
83		* {@code forceTermination}.
84		*
85	+	* <li>Phasers ensure lack of starvation when used by ForkJoinTasks.
86	+	*
87		* </ul>
88		*
89		* <p><b>Sample usages:</b>
#	Line 90 | Line 93 | import java.lang.reflect.*;
93		* idiom is for the method setting this up to first register, then
94		* start the actions, then deregister, as in:
95		*
96	<	* <pre>
97	<	*  void runTasks(List&lt;Runnable&gt; list) {
98	<	*    final Phaser phaser = new Phaser(1); // "1" to register self
99	<	*    for (Runnable r : list) {
100	<	*      phaser.register();
101	<	*      new Thread() {
102	<	*        public void run() {
103	<	*          phaser.arriveAndAwaitAdvance(); // await all creation
104	<	*          r.run();
105	<	*          phaser.arriveAndDeregister();   // signal completion
106	<	*        }
107	<	*      }.start();
96	>	*  <pre> {@code
97	>	* void runTasks(List<Runnable> list) {
98	>	*   final Phaser phaser = new Phaser(1); // "1" to register self
99	>	*   for (Runnable r : list) {
100	>	*     phaser.register();
101	>	*     new Thread() {
102	>	*       public void run() {
103	>	*         phaser.arriveAndAwaitAdvance(); // await all creation
104	>	*         r.run();
105	>	*         phaser.arriveAndDeregister();   // signal completion
106	>	*       }
107	>	*     }.start();
108		*   }
109		*
110		*   doSomethingOnBehalfOfWorkers();
#	Line 110 | Line 113 | import java.lang.reflect.*;
113		*   p = phaser.awaitAdvance(p); // ... and await arrival
114		*   otherActions(); // do other things while tasks execute
115		*   phaser.awaitAdvance(p); // await final completion
116	<	* }
114	<	* </pre>
116	>	* }}</pre>
117		*
118		* <p>One way to cause a set of threads to repeatedly perform actions
119		* for a given number of iterations is to override {@code onAdvance}:
120		*
121	<	* <pre>
122	<	*  void startTasks(List&lt;Runnable&gt; list, final int iterations) {
123	<	*    final Phaser phaser = new Phaser() {
124	<	*       public boolean onAdvance(int phase, int registeredParties) {
125	<	*         return phase &gt;= iterations || registeredParties == 0;
121	>	*  <pre> {@code
122	>	* void startTasks(List<Runnable> list, final int iterations) {
123	>	*   final Phaser phaser = new Phaser() {
124	>	*     public boolean onAdvance(int phase, int registeredParties) {
125	>	*       return phase >= iterations || registeredParties == 0;
126	>	*     }
127	>	*   };
128	>	*   phaser.register();
129	>	*   for (Runnable r : list) {
130	>	*     phaser.register();
131	>	*     new Thread() {
132	>	*       public void run() {
133	>	*         do {
134	>	*           r.run();
135	>	*           phaser.arriveAndAwaitAdvance();
136	>	*         } while(!phaser.isTerminated();
137		*       }
138	<	*    };
126	<	*    phaser.register();
127	<	*    for (Runnable r : list) {
128	<	*      phaser.register();
129	<	*      new Thread() {
130	<	*        public void run() {
131	<	*           do {
132	<	*             r.run();
133	<	*             phaser.arriveAndAwaitAdvance();
134	<	*           } while(!phaser.isTerminated();
135	<	*        }
136	<	*      }.start();
138	>	*     }.start();
139		*   }
140		*   phaser.arriveAndDeregister(); // deregister self, don't wait
141	<	* }
140	<	* </pre>
141	>	* }}</pre>
142		*
143		* <p> To create a set of tasks using a tree of Phasers,
144		* you could use code of the following form, assuming a
145		* Task class with a constructor accepting a Phaser that
146		* it registers for upon construction:
147	<	* <pre>
148	<	*  void build(Task[] actions, int lo, int hi, Phaser b) {
149	<	*    int step = (hi - lo) / TASKS_PER_PHASER;
150	<	*    if (step &gt; 1) {
151	<	*       int i = lo;
152	<	*       while (i &lt; hi) {
153	<	*         int r = Math.min(i + step, hi);
154	<	*         build(actions, i, r, new Phaser(b));
155	<	*         i = r;
156	<	*       }
157	<	*    }
158	<	*    else {
159	<	*      for (int i = lo; i &lt; hi; ++i)
160	<	*        actions[i] = new Task(b);
161	<	*        // assumes new Task(b) performs b.register()
162	<	*    }
163	<	*  }
164	<	*  // .. initially called, for n tasks via
164	<	*  build(new Task[n], 0, n, new Phaser());
165	<	* </pre>
147	>	*  <pre> {@code
148	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
149	>	*   int step = (hi - lo) / TASKS_PER_PHASER;
150	>	*   if (step > 1) {
151	>	*     int i = lo;
152	>	*     while (i < hi) {
153	>	*       int r = Math.min(i + step, hi);
154	>	*       build(actions, i, r, new Phaser(b));
155	>	*       i = r;
156	>	*     }
157	>	*   } else {
158	>	*     for (int i = lo; i < hi; ++i)
159	>	*       actions[i] = new Task(b);
160	>	*       // assumes new Task(b) performs b.register()
161	>	*   }
162	>	* }
163	>	* // .. initially called, for n tasks via
164	>	* build(new Task[n], 0, n, new Phaser());}</pre>
165		*
166		* The best value of {@code TASKS_PER_PHASER} depends mainly on
167		* expected barrier synchronization rates. A value as low as four may
#	Line 176 | Line 175 | import java.lang.reflect.*;
175		* parties result in IllegalStateExceptions. However, you can and
176		* should create tiered phasers to accommodate arbitrarily large sets
177		* of participants.
178	+	*
179	+	* @since 1.7
180	+	* @author Doug Lea
181		*/
182		public class Phaser {
183		/*
#	Line 200 | Line 202 | public class Phaser {
202		* and encoding simple, and keeping race windows short.
203		*
204		* Note: there are some cheats in arrive() that rely on unarrived
205	<	* being lowest 16 bits.
205	>	* count being lowest 16 bits.
206		*/
207		private volatile long state;
208
209		private static final int ushortBits = 16;
210	<	private static final int ushortMask =  (1 << ushortBits) - 1;
211	<	private static final int phaseMask = 0x7fffffff;
210	>	private static final int ushortMask = 0xffff;
211	>	private static final int phaseMask  = 0x7fffffff;
212
213		private static int unarrivedOf(long s) {
214		return (int)(s & ushortMask);
215		}
216
217		private static int partiesOf(long s) {
218	<	return (int)(s & (ushortMask << 16)) >>> 16;
218	>	return ((int)s) >>> 16;
219		}
220
221		private static int phaseOf(long s) {
#	Line 225 | Line 227 | public class Phaser {
227		}
228
229		private static long stateFor(int phase, int parties, int unarrived) {
230	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
230	>	return ((((long)phase) << 32) | (((long)parties) << 16) |
231	>	(long)unarrived);
232		}
233
234		private static long trippedStateFor(int phase, int parties) {
235	<	return (((long)phase) << 32) | ((parties << 16) | parties);
235	>	long lp = (long)parties;
236	>	return (((long)phase) << 32) | (lp << 16) | lp;
237		}
238
239	<	private static IllegalStateException badBounds(int parties, int unarrived) {
240	<	return new IllegalStateException
241	<	("Attempt to set " + unarrived +
242	<	" unarrived of " + parties + " parties");
239	>	/**
240	>	* Returns message string for bad bounds exceptions.
241	>	*/
242	>	private static String badBounds(int parties, int unarrived) {
243	>	return ("Attempt to set " + unarrived +
244	>	" unarrived of " + parties + " parties");
245		}
246
247		/**
#	Line 252 | Line 258 | public class Phaser {
258		// Wait queues
259
260		/**
261	<	* Heads of Treiber stacks waiting for nonFJ threads. To eliminate
261	>	* Heads of Treiber stacks for waiting threads. To eliminate
262		* contention while releasing some threads while adding others, we
263		* use two of them, alternating across even and odd phases.
264		*/
#	Line 296 | Line 302 | public class Phaser {
302
303		/**
304		* Creates a new Phaser without any initially registered parties,
305	<	* initial phase number 0, and no parent.
305	>	* initial phase number 0, and no parent. Any thread using this
306	>	* Phaser will need to first register for it.
307		*/
308		public Phaser() {
309		this(null);
#	Line 305 | Line 312 | public class Phaser {
312		/**
313		* Creates a new Phaser with the given numbers of registered
314		* unarrived parties, initial phase number 0, and no parent.
315	<	* @param parties the number of parties required to trip barrier.
315	>	*
316	>	* @param parties the number of parties required to trip barrier
317		* @throws IllegalArgumentException if parties less than zero
318	<	* or greater than the maximum number of parties supported.
318	>	* or greater than the maximum number of parties supported
319		*/
320		public Phaser(int parties) {
321		this(null, parties);
#	Line 318 | Line 326 | public class Phaser {
326		* initially registered parties. If parent is non-null this phaser
327		* is registered with the parent and its initial phase number is
328		* the same as that of parent phaser.
329	<	* @param parent the parent phaser.
329	>	*
330	>	* @param parent the parent phaser
331		*/
332		public Phaser(Phaser parent) {
333		int phase = 0;
#	Line 334 | Line 343 | public class Phaser {
343
344		/**
345		* Creates a new Phaser with the given parent and numbers of
346	<	* registered unarrived parties. If parent is non-null this phaser
346	>	* registered unarrived parties. If parent is non-null, this phaser
347		* is registered with the parent and its initial phase number is
348		* the same as that of parent phaser.
349	<	* @param parent the parent phaser.
350	<	* @param parties the number of parties required to trip barrier.
349	>	*
350	>	* @param parent the parent phaser
351	>	* @param parties the number of parties required to trip barrier
352		* @throws IllegalArgumentException if parties less than zero
353	<	* or greater than the maximum number of parties supported.
353	>	* or greater than the maximum number of parties supported
354		*/
355		public Phaser(Phaser parent, int parties) {
356		if (parties < 0 || parties > ushortMask)
#	Line 358 | Line 368 | public class Phaser {
368
369		/**
370		* Adds a new unarrived party to this phaser.
371	+	*
372		* @return the current barrier phase number upon registration
373		* @throws IllegalStateException if attempting to register more
374	<	* than the maximum supported number of parties.
374	>	* than the maximum supported number of parties
375		*/
376		public int register() {
377		return doRegister(1);
#	Line 368 | Line 379 | public class Phaser {
379
380		/**
381		* Adds the given number of new unarrived parties to this phaser.
382	<	* @param parties the number of parties required to trip barrier.
382	>	*
383	>	* @param parties the number of parties required to trip barrier
384		* @return the current barrier phase number upon registration
385		* @throws IllegalStateException if attempting to register more
386	<	* than the maximum supported number of parties.
386	>	* than the maximum supported number of parties
387		*/
388		public int bulkRegister(int parties) {
389		if (parties < 0)
#	Line 394 | Line 406 | public class Phaser {
406		if (phase < 0)
407		break;
408		if (parties > ushortMask || unarrived > ushortMask)
409	<	throw badBounds(parties, unarrived);
409	>	throw new IllegalStateException(badBounds(parties, unarrived));
410		if (phase == phaseOf(root.state) &&
411		casState(s, stateFor(phase, parties, unarrived)))
412		break;
#	Line 407 | Line 419 | public class Phaser {
419		* in turn wait for others via {@link #awaitAdvance}).
420		*
421		* @return the barrier phase number upon entry to this method, or a
422	<	* negative value if terminated;
422	>	* negative value if terminated
423		* @throws IllegalStateException if not terminated and the number
424	<	* of unarrived parties would become negative.
424	>	* of unarrived parties would become negative
425		*/
426		public int arrive() {
427		int phase;
428		for (;;) {
429		long s = state;
430		phase = phaseOf(s);
431	+	if (phase < 0)
432	+	break;
433		int parties = partiesOf(s);
434		int unarrived = unarrivedOf(s) - 1;
435		if (unarrived > 0) {        // Not the last arrival
#	Line 441 | Line 455 | public class Phaser {
455		}
456		}
457		}
444	–	else if (phase < 0) // Don't throw exception if terminated
445	–	break;
458		else if (phase != phaseOf(root.state)) // or if unreconciled
459		reconcileState();
460		else
461	<	throw badBounds(parties, unarrived);
461	>	throw new IllegalStateException(badBounds(parties, unarrived));
462		}
463		return phase;
464		}
#	Line 459 | Line 471 | public class Phaser {
471		* zero parties, this phaser is also deregistered from its parent.
472		*
473		* @return the current barrier phase number upon entry to
474	<	* this method, or a negative value if terminated;
474	>	* this method, or a negative value if terminated
475		* @throws IllegalStateException if not terminated and the number
476	<	* of registered or unarrived parties would become negative.
476	>	* of registered or unarrived parties would become negative
477		*/
478		public int arriveAndDeregister() {
479		// similar code to arrive, but too different to merge
#	Line 470 | Line 482 | public class Phaser {
482		for (;;) {
483		long s = state;
484		phase = phaseOf(s);
485	+	if (phase < 0)
486	+	break;
487		int parties = partiesOf(s) - 1;
488		int unarrived = unarrivedOf(s) - 1;
489		if (parties >= 0) {
#	Line 495 | Line 509 | public class Phaser {
509		}
510		continue;
511		}
498	–	if (phase < 0)
499	–	break;
512		if (par != null && phase != phaseOf(root.state)) {
513		reconcileState();
514		continue;
515		}
516		}
517	<	throw badBounds(parties, unarrived);
517	>	throw new IllegalStateException(badBounds(parties, unarrived));
518		}
519		return phase;
520		}
#	Line 512 | Line 524 | public class Phaser {
524		* to {@code awaitAdvance(arrive())}.  If you instead need to
525		* await with interruption of timeout, and/or deregister upon
526		* arrival, you can arrange them using analogous constructions.
527	+	*
528		* @return the phase on entry to this method
529		* @throws IllegalStateException if not terminated and the number
530	<	* of unarrived parties would become negative.
530	>	* of unarrived parties would become negative
531		*/
532		public int arriveAndAwaitAdvance() {
533		return awaitAdvance(arrive());
#	Line 524 | Line 537 | public class Phaser {
537		* Awaits the phase of the barrier to advance from the given
538		* value, or returns immediately if argument is negative or this
539		* barrier is terminated.
540	+	*
541		* @param phase the phase on entry to this method
542		* @return the phase on exit from this method
543		*/
#	Line 534 | Line 548 | public class Phaser {
548		int p = phaseOf(s);
549		if (p != phase)
550		return p;
551	<	if (unarrivedOf(s) == 0)
551	>	if (unarrivedOf(s) == 0 && parent != null)
552		parent.awaitAdvance(phase);
553		// Fall here even if parent waited, to reconcile and help release
554		return untimedWait(phase);
#	Line 545 | Line 559 | public class Phaser {
559		* value, or returns immediately if argument is negative or this
560		* barrier is terminated, or throws InterruptedException if
561		* interrupted while waiting.
562	+	*
563		* @param phase the phase on entry to this method
564		* @return the phase on exit from this method
565		* @throws InterruptedException if thread interrupted while waiting
566		*/
567	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
567	>	public int awaitAdvanceInterruptibly(int phase)
568	>	throws InterruptedException {
569		if (phase < 0)
570		return phase;
571		long s = getReconciledState();
572		int p = phaseOf(s);
573		if (p != phase)
574		return p;
575	<	if (unarrivedOf(s) != 0)
575	>	if (unarrivedOf(s) == 0 && parent != null)
576		parent.awaitAdvanceInterruptibly(phase);
577		return interruptibleWait(phase);
578		}
#	Line 565 | Line 581 | public class Phaser {
581		* Awaits the phase of the barrier to advance from the given value
582		* or the given timeout elapses, or returns immediately if
583		* argument is negative or this barrier is terminated.
584	+	*
585		* @param phase the phase on entry to this method
586		* @return the phase on exit from this method
587		* @throws InterruptedException if thread interrupted while waiting
#	Line 578 | Line 595 | public class Phaser {
595		int p = phaseOf(s);
596		if (p != phase)
597		return p;
598	<	if (unarrivedOf(s) == 0)
598	>	if (unarrivedOf(s) == 0 && parent != null)
599		parent.awaitAdvanceInterruptibly(phase, timeout, unit);
600		return timedWait(phase, unit.toNanos(timeout));
601		}
#	Line 611 | Line 628 | public class Phaser {
628		* Returns the current phase number. The maximum phase number is
629		* {@code Integer.MAX_VALUE}, after which it restarts at
630		* zero. Upon termination, the phase number is negative.
631	+	*
632		* @return the phase number, or a negative value if terminated
633		*/
634		public final int getPhase() {
#	Line 619 | Line 637 | public class Phaser {
637
638		/**
639		* Returns {@code true} if the current phase number equals the given phase.
640	+	*
641		* @param phase the phase
642		* @return {@code true} if the current phase number equals the given phase
643		*/
#	Line 628 | Line 647 | public class Phaser {
647
648		/**
649		* Returns the number of parties registered at this barrier.
650	+	*
651		* @return the number of parties
652		*/
653		public int getRegisteredParties() {
#	Line 637 | Line 657 | public class Phaser {
657		/**
658		* Returns the number of parties that have arrived at the current
659		* phase of this barrier.
660	+	*
661		* @return the number of arrived parties
662		*/
663		public int getArrivedParties() {
#	Line 646 | Line 667 | public class Phaser {
667		/**
668		* Returns the number of registered parties that have not yet
669		* arrived at the current phase of this barrier.
670	+	*
671		* @return the number of unarrived parties
672		*/
673		public int getUnarrivedParties() {
#	Line 654 | Line 676 | public class Phaser {
676
677		/**
678		* Returns the parent of this phaser, or null if none.
679	+	*
680		* @return the parent of this phaser, or null if none
681		*/
682		public Phaser getParent() {
#	Line 663 | Line 686 | public class Phaser {
686		/**
687		* Returns the root ancestor of this phaser, which is the same as
688		* this phaser if it has no parent.
689	+	*
690		* @return the root ancestor of this phaser
691		*/
692		public Phaser getRoot() {
#	Line 671 | Line 695 | public class Phaser {
695
696		/**
697		* Returns {@code true} if this barrier has been terminated.
698	+	*
699		* @return {@code true} if this barrier has been terminated
700		*/
701		public boolean isTerminated() {
#	Line 729 | Line 754 | public class Phaser {
754
755		// methods for waiting
756
732	–	/** The number of CPUs, for spin control */
733	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
734	–
757		/**
758	<	* The number of times to spin before blocking in timed waits.
737	<	* The value is empirically derived.
758	>	* Wait nodes for Treiber stack representing wait queue
759		*/
760	<	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
761	<
762	<	/**
763	<	* The number of times to spin before blocking in untimed waits.
764	<	* This is greater than timed value because untimed waits spin
765	<	* faster since they don't need to check times on each spin.
766	<	*/
767	<	static final int maxUntimedSpins = maxTimedSpins * 32;
747	<
748	<	/**
749	<	* The number of nanoseconds for which it is faster to spin
750	<	* rather than to use timed park. A rough estimate suffices.
751	<	*/
752	<	static final long spinForTimeoutThreshold = 1000L;
753	<
754	<	/**
755	<	* Wait nodes for Treiber stack representing wait queue for non-FJ
756	<	* tasks.
757	<	*/
758	<	static final class QNode {
759	<	QNode next;
760	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
761	>	final Phaser phaser;
762	>	final int phase;
763	>	final long startTime;
764	>	final long nanos;
765	>	final boolean timed;
766	>	final boolean interruptible;
767	>	volatile boolean wasInterrupted = false;
768		volatile Thread thread; // nulled to cancel wait
769	<	QNode() {
769	>	QNode next;
770	>	QNode(Phaser phaser, int phase, boolean interruptible,
771	>	boolean timed, long startTime, long nanos) {
772	>	this.phaser = phaser;
773	>	this.phase = phase;
774	>	this.timed = timed;
775	>	this.interruptible = interruptible;
776	>	this.startTime = startTime;
777	>	this.nanos = nanos;
778		thread = Thread.currentThread();
779		}
780	+	public boolean isReleasable() {
781	+	return (thread == null ||
782	+	phaser.getPhase() != phase ||
783	+	(interruptible && wasInterrupted) ||
784	+	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
785	+	}
786	+	public boolean block() {
787	+	if (Thread.interrupted()) {
788	+	wasInterrupted = true;
789	+	if (interruptible)
790	+	return true;
791	+	}
792	+	if (!timed)
793	+	LockSupport.park(this);
794	+	else {
795	+	long waitTime = nanos - (System.nanoTime() - startTime);
796	+	if (waitTime <= 0)
797	+	return true;
798	+	LockSupport.parkNanos(this, waitTime);
799	+	}
800	+	return isReleasable();
801	+	}
802		void signal() {
803		Thread t = thread;
804		if (t != null) {
#	Line 768 | Line 806 | public class Phaser {
806		LockSupport.unpark(t);
807		}
808		}
809	+	boolean doWait() {
810	+	if (thread != null) {
811	+	try {
812	+	ForkJoinPool.managedBlock(this, false);
813	+	} catch (InterruptedException ie) {
814	+	}
815	+	}
816	+	return wasInterrupted;
817	+	}
818	+
819		}
820
821		/**
822	<	* Removes and signals waiting threads from wait queue
822	>	* Removes and signals waiting threads from wait queue.
823		*/
824		private void releaseWaiters(int phase) {
825		AtomicReference<QNode> head = queueFor(phase);
#	Line 783 | Line 831 | public class Phaser {
831		}
832
833		/**
834	+	* Tries to enqueue given node in the appropriate wait queue.
835	+	*
836	+	* @return true if successful
837	+	*/
838	+	private boolean tryEnqueue(QNode node) {
839	+	AtomicReference<QNode> head = queueFor(node.phase);
840	+	return head.compareAndSet(node.next = head.get(), node);
841	+	}
842	+
843	+	/**
844		* Enqueues node and waits unless aborted or signalled.
845	+	*
846	+	* @return current phase
847		*/
848		private int untimedWait(int phase) {
789	–	int spins = maxUntimedSpins;
849		QNode node = null;
791	–	boolean interrupted = false;
850		boolean queued = false;
851	+	boolean interrupted = false;
852		int p;
853		while ((p = getPhase()) == phase) {
854	<	interrupted = Thread.interrupted();
855	<	if (node != null) {
856	<	if (!queued) {
857	<	AtomicReference<QNode> head = queueFor(phase);
858	<	queued = head.compareAndSet(node.next = head.get(), node);
859	<	}
801	<	else if (node.thread != null)
802	<	LockSupport.park(this);
803	<	}
804	<	else if (spins <= 0)
805	<	node = new QNode();
854	>	if (Thread.interrupted())
855	>	interrupted = true;
856	>	else if (node == null)
857	>	node = new QNode(this, phase, false, false, 0, 0);
858	>	else if (!queued)
859	>	queued = tryEnqueue(node);
860		else
861	<	--spins;
861	>	interrupted = node.doWait();
862		}
863		if (node != null)
864		node.thread = null;
865	+	releaseWaiters(phase);
866		if (interrupted)
867		Thread.currentThread().interrupt();
813	–	releaseWaiters(phase);
868		return p;
869		}
870
871		/**
872	<	* Messier interruptible version
872	>	* Interruptible version
873	>	* @return current phase
874		*/
875		private int interruptibleWait(int phase) throws InterruptedException {
821	–	int spins = maxUntimedSpins;
876		QNode node = null;
877		boolean queued = false;
878		boolean interrupted = false;
879		int p;
880	<	while ((p = getPhase()) == phase) {
881	<	if (interrupted = Thread.interrupted())
882	<	break;
883	<	if (node != null) {
884	<	if (!queued) {
885	<	AtomicReference<QNode> head = queueFor(phase);
886	<	queued = head.compareAndSet(node.next = head.get(), node);
833	<	}
834	<	else if (node.thread != null)
835	<	LockSupport.park(this);
836	<	}
837	<	else if (spins <= 0)
838	<	node = new QNode();
880	>	while ((p = getPhase()) == phase && !interrupted) {
881	>	if (Thread.interrupted())
882	>	interrupted = true;
883	>	else if (node == null)
884	>	node = new QNode(this, phase, true, false, 0, 0);
885	>	else if (!queued)
886	>	queued = tryEnqueue(node);
887		else
888	<	--spins;
888	>	interrupted = node.doWait();
889		}
890		if (node != null)
891		node.thread = null;
892	+	if (p != phase || (p = getPhase()) != phase)
893	+	releaseWaiters(phase);
894		if (interrupted)
895		throw new InterruptedException();
846	–	releaseWaiters(phase);
896		return p;
897		}
898
899		/**
900	<	* Even messier timeout version.
900	>	* Timeout version.
901	>	* @return current phase
902		*/
903		private int timedWait(int phase, long nanos)
904		throws InterruptedException, TimeoutException {
905	+	long startTime = System.nanoTime();
906	+	QNode node = null;
907	+	boolean queued = false;
908	+	boolean interrupted = false;
909		int p;
910	<	if ((p = getPhase()) == phase) {
911	<	long lastTime = System.nanoTime();
912	<	int spins = maxTimedSpins;
913	<	QNode node = null;
914	<	boolean queued = false;
915	<	boolean interrupted = false;
916	<	while ((p = getPhase()) == phase) {
917	<	if (interrupted = Thread.interrupted())
918	<	break;
919	<	long now = System.nanoTime();
920	<	if ((nanos -= now - lastTime) <= 0)
867	<	break;
868	<	lastTime = now;
869	<	if (node != null) {
870	<	if (!queued) {
871	<	AtomicReference<QNode> head = queueFor(phase);
872	<	queued = head.compareAndSet(node.next = head.get(), node);
873	<	}
874	<	else if (node.thread != null &&
875	<	nanos > spinForTimeoutThreshold) {
876	<	LockSupport.parkNanos(this, nanos);
877	<	}
878	<	}
879	<	else if (spins <= 0)
880	<	node = new QNode();
881	<	else
882	<	--spins;
883	<	}
884	<	if (node != null)
885	<	node.thread = null;
886	<	if (interrupted)
887	<	throw new InterruptedException();
888	<	if (p == phase && (p = getPhase()) == phase)
889	<	throw new TimeoutException();
910	>	while ((p = getPhase()) == phase && !interrupted) {
911	>	if (Thread.interrupted())
912	>	interrupted = true;
913	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
914	>	break;
915	>	else if (node == null)
916	>	node = new QNode(this, phase, true, true, startTime, nanos);
917	>	else if (!queued)
918	>	queued = tryEnqueue(node);
919	>	else
920	>	interrupted = node.doWait();
921		}
922	<	releaseWaiters(phase);
922	>	if (node != null)
923	>	node.thread = null;
924	>	if (p != phase || (p = getPhase()) != phase)
925	>	releaseWaiters(phase);
926	>	if (interrupted)
927	>	throw new InterruptedException();
928	>	if (p == phase)
929	>	throw new TimeoutException();
930		return p;
931		}
932
933		// Temporary Unsafe mechanics for preliminary release
934	+	private static Unsafe getUnsafe() throws Throwable {
935	+	try {
936	+	return Unsafe.getUnsafe();
937	+	} catch (SecurityException se) {
938	+	try {
939	+	return java.security.AccessController.doPrivileged
940	+	(new java.security.PrivilegedExceptionAction<Unsafe>() {
941	+	public Unsafe run() throws Exception {
942	+	return getUnsafePrivileged();
943	+	}});
944	+	} catch (java.security.PrivilegedActionException e) {
945	+	throw e.getCause();
946	+	}
947	+	}
948	+	}
949
950	<	static final Unsafe _unsafe;
950	>	private static Unsafe getUnsafePrivileged()
951	>	throws NoSuchFieldException, IllegalAccessException {
952	>	Field f = Unsafe.class.getDeclaredField("theUnsafe");
953	>	f.setAccessible(true);
954	>	return (Unsafe) f.get(null);
955	>	}
956	>
957	>	private static long fieldOffset(String fieldName)
958	>	throws NoSuchFieldException {
959	>	return UNSAFE.objectFieldOffset
960	>	(Phaser.class.getDeclaredField(fieldName));
961	>	}
962	>
963	>	static final Unsafe UNSAFE;
964		static final long stateOffset;
965
966		static {
967		try {
968	<	if (Phaser.class.getClassLoader() != null) {
969	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
970	<	f.setAccessible(true);
905	<	_unsafe = (Unsafe)f.get(null);
906	<	}
907	<	else
908	<	_unsafe = Unsafe.getUnsafe();
909	<	stateOffset = _unsafe.objectFieldOffset
910	<	(Phaser.class.getDeclaredField("state"));
911	<	} catch (Exception e) {
968	>	UNSAFE = getUnsafe();
969	>	stateOffset = fieldOffset("state");
970	>	} catch (Throwable e) {
971		throw new RuntimeException("Could not initialize intrinsics", e);
972		}
973		}
974
975		final boolean casState(long cmp, long val) {
976	<	return _unsafe.compareAndSwapLong(this, stateOffset, cmp, val);
976	>	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
977		}
978		}

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