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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.6 by dl, Tue Oct 28 23:03:24 2008 UTC vs.
Revision 1.11 by jsr166, Thu Mar 19 04:49:44 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	+
9		import java.util.concurrent.*;
10		import java.util.concurrent.atomic.*;
11		import java.util.concurrent.locks.LockSupport;
#	Line 13 | Line 14 | import java.lang.reflect.*;
14
15		/**
16		* A reusable synchronization barrier, similar in functionality to a
17	<	* {@link java.util.concurrent.CyclicBarrier} and {@link
18	<	* java.util.concurrent.CountDownLatch} but supporting more flexible
19	<	* usage.
17	>	* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and
18	>	* {@link java.util.concurrent.CountDownLatch CountDownLatch}
19	>	* but supporting more flexible usage.
20		*
21		* <ul>
22		*
#	Line 25 | Line 26 | import java.lang.reflect.*;
26		* basic synchronization constructs, registration and deregistration
27		* affect only internal counts; they do not establish any further
28		* internal bookkeeping, so tasks cannot query whether they are
29	<	* registered. (However, you can introduce such bookkeeping in by
29	>	* registered. (However, you can introduce such bookkeeping by
30		* subclassing this class.)
31		*
32		* <li> Each generation has an associated phase value, starting at
33		* zero, and advancing when all parties reach the barrier (wrapping
34	<	* around to zero after reaching <tt>Integer.MAX_VALUE</tt>).
34	>	* around to zero after reaching {@code Integer.MAX_VALUE}).
35		*
36		* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
37	<	* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to
38	<	* <tt>CyclicBarrier.await</tt>.  However, Phasers separate two
37	>	* Method {@code arriveAndAwaitAdvance} has effect analogous to
38	>	* {@code CyclicBarrier.await}.  However, Phasers separate two
39		* aspects of coordination, that may also be invoked independently:
40		*
41		* <ul>
42		*
43	<	*   <li> Arriving at a barrier. Methods <tt>arrive</tt> and
44	<	*       <tt>arriveAndDeregister</tt> do not block, but return
43	>	*   <li> Arriving at a barrier. Methods {@code arrive} and
44	>	*       {@code arriveAndDeregister} do not block, but return
45		*       the phase value current upon entry to the method.
46		*
47	<	*   <li> Awaiting others. Method <tt>awaitAdvance</tt> requires an
47	>	*   <li> Awaiting others. Method {@code awaitAdvance} requires an
48		*       argument indicating the entry phase, and returns when the
49		*       barrier advances to a new phase.
50		* </ul>
#	Line 51 | Line 52 | import java.lang.reflect.*;
52		*
53		* <li> Barrier actions, performed by the task triggering a phase
54		* advance while others may be waiting, are arranged by overriding
55	<	* method <tt>onAdvance</tt>, that also controls termination.
55	>	* method {@code onAdvance}, that also controls termination.
56		* Overriding this method may be used to similar but more flexible
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 <tt>onAdvance</tt> 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	<	* <tt>forceTermination</tt> 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 72 | Line 74 | import java.lang.reflect.*;
74		* This will typically greatly increase throughput even though it
75		* incurs somewhat greater per-operation overhead.
76		*
77	<	* <li> By default, <tt>awaitAdvance</tt> continues to wait even if
77	>	* <li> By default, {@code awaitAdvance} continues to wait even if
78		* the waiting thread is interrupted. And unlike the case in
79		* CyclicBarriers, exceptions encountered while tasks wait
80		* interruptibly or with timeout do not change the state of the
81		* barrier. If necessary, you can perform any associated recovery
82		* within handlers of those exceptions, often after invoking
83	<	* <tt>forceTermination</tt>.
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>
90		*
91	<	* <p>A Phaser may be used instead of a <tt>CountdownLatch</tt> to control
91	>	* <p>A Phaser may be used instead of a {@code CountDownLatch} to control
92		* a one-shot action serving a variable number of parties. The typical
93		* idiom is for the method setting this up to first register, then
94		* start the actions, then deregister, as in:
#	Line 108 | Line 112 | import java.lang.reflect.*;
112		*   int p = phaser.arriveAndDeregister(); // deregister self  ...
113		*   p = phaser.awaitAdvance(p); // ... and await arrival
114		*   otherActions(); // do other things while tasks execute
115	<	*   phaser.awaitAdvance(p); // awit final completion
115	>	*   phaser.awaitAdvance(p); // await final completion
116		* }
117		* </pre>
118		*
119		* <p>One way to cause a set of threads to repeatedly perform actions
120	<	* for a given number of iterations is to override <tt>onAdvance</tt>:
120	>	* for a given number of iterations is to override {@code onAdvance}:
121		*
122		* <pre>
123		*  void startTasks(List&lt;Runnable&gt; list, final int iterations) {
#	Line 163 | Line 167 | import java.lang.reflect.*;
167		*  build(new Task[n], 0, n, new Phaser());
168		* </pre>
169		*
170	<	* The best value of <tt>TASKS_PER_PHASER</tt> depends mainly on
170	>	* The best value of {@code TASKS_PER_PHASER} depends mainly on
171		* expected barrier synchronization rates. A value as low as four may
172		* be appropriate for extremely small per-barrier task bodies (thus
173		* high rates), or up to hundreds for extremely large ones.
#	Line 195 | Line 199 | public class Phaser {
199		* However, to efficiently maintain atomicity, these values are
200		* packed into a single (atomic) long. Termination uses the sign
201		* bit of 32 bit representation of phase, so phase is set to -1 on
202	<	* termination. Good performace relies on keeping state decoding
202	>	* termination. Good performance relies on keeping state decoding
203		* and encoding simple, and keeping race windows short.
204		*
205		* Note: there are some cheats in arrive() that rely on unarrived
206	<	* being lowest 16 bits.
206	>	* count being lowest 16 bits.
207		*/
208		private volatile long state;
209
210		private static final int ushortBits = 16;
211	<	private static final int ushortMask =  (1 << ushortBits) - 1;
212	<	private static final int phaseMask = 0x7fffffff;
211	>	private static final int ushortMask = 0xffff;
212	>	private static final int phaseMask  = 0x7fffffff;
213
214		private static int unarrivedOf(long s) {
215		return (int)(s & ushortMask);
216		}
217
218		private static int partiesOf(long s) {
219	<	return (int)(s & (ushortMask << 16)) >>> 16;
219	>	return ((int)s) >>> 16;
220		}
221
222		private static int phaseOf(long s) {
#	Line 224 | Line 228 | public class Phaser {
228		}
229
230		private static long stateFor(int phase, int parties, int unarrived) {
231	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
231	>	return ((((long)phase) << 32) | (((long)parties) << 16) |
232	>	(long)unarrived);
233		}
234
235		private static long trippedStateFor(int phase, int parties) {
236	<	return (((long)phase) << 32) | ((parties << 16) | parties);
236	>	long lp = (long)parties;
237	>	return (((long)phase) << 32) | (lp << 16) | lp;
238		}
239
240	<	private static IllegalStateException badBounds(int parties, int unarrived) {
241	<	return new IllegalStateException
242	<	("Attempt to set " + unarrived +
243	<	" unarrived of " + parties + " parties");
240	>	/**
241	>	* Returns message string for bad bounds exceptions
242	>	*/
243	>	private static String badBounds(int parties, int unarrived) {
244	>	return ("Attempt to set " + unarrived +
245	>	" unarrived of " + parties + " parties");
246		}
247
248		/**
#	Line 251 | Line 259 | public class Phaser {
259		// Wait queues
260
261		/**
262	<	* Heads of Treiber stacks waiting for nonFJ threads. To eliminate
262	>	* Heads of Treiber stacks for waiting threads. To eliminate
263		* contention while releasing some threads while adding others, we
264		* use two of them, alternating across even and odd phases.
265		*/
#	Line 295 | Line 303 | public class Phaser {
303
304		/**
305		* Creates a new Phaser without any initially registered parties,
306	<	* initial phase number 0, and no parent.
306	>	* initial phase number 0, and no parent. Any thread using this
307	>	* Phaser will need to first register for it.
308		*/
309		public Phaser() {
310		this(null);
#	Line 390 | Line 399 | public class Phaser {
399		phase = phaseOf(s);
400		int unarrived = unarrivedOf(s) + registrations;
401		int parties = partiesOf(s) + registrations;
402	<	if (phase < 0)
402	>	if (phase < 0)
403		break;
404		if (parties > ushortMask || unarrived > ushortMask)
405	<	throw badBounds(parties, unarrived);
405	>	throw new IllegalStateException(badBounds(parties, unarrived));
406		if (phase == phaseOf(root.state) &&
407		casState(s, stateFor(phase, parties, unarrived)))
408		break;
#	Line 415 | Line 424 | public class Phaser {
424		for (;;) {
425		long s = state;
426		phase = phaseOf(s);
427	+	if (phase < 0)
428	+	break;
429		int parties = partiesOf(s);
430		int unarrived = unarrivedOf(s) - 1;
431		if (unarrived > 0) {        // Not the last arrival
#	Line 440 | Line 451 | public class Phaser {
451		}
452		}
453		}
443	–	else if (phase < 0) // Don't throw exception if terminated
444	–	break;
454		else if (phase != phaseOf(root.state)) // or if unreconciled
455		reconcileState();
456		else
457	<	throw badBounds(parties, unarrived);
457	>	throw new IllegalStateException(badBounds(parties, unarrived));
458		}
459		return phase;
460		}
#	Line 469 | Line 478 | public class Phaser {
478		for (;;) {
479		long s = state;
480		phase = phaseOf(s);
481	+	if (phase < 0)
482	+	break;
483		int parties = partiesOf(s) - 1;
484		int unarrived = unarrivedOf(s) - 1;
485		if (parties >= 0) {
#	Line 494 | Line 505 | public class Phaser {
505		}
506		continue;
507		}
497	–	if (phase < 0)
498	–	break;
508		if (par != null && phase != phaseOf(root.state)) {
509		reconcileState();
510		continue;
511		}
512		}
513	<	throw badBounds(parties, unarrived);
513	>	throw new IllegalStateException(badBounds(parties, unarrived));
514		}
515		return phase;
516		}
517
518		/**
519		* Arrives at the barrier and awaits others. Equivalent in effect
520	<	* to <tt>awaitAdvance(arrive())</tt>.  If you instead need to
520	>	* to {@code awaitAdvance(arrive())}.  If you instead need to
521		* await with interruption of timeout, and/or deregister upon
522		* arrival, you can arrange them using analogous constructions.
523		* @return the phase on entry to this method
#	Line 533 | Line 542 | public class Phaser {
542		int p = phaseOf(s);
543		if (p != phase)
544		return p;
545	<	if (unarrivedOf(s) == 0)
545	>	if (unarrivedOf(s) == 0 && parent != null)
546		parent.awaitAdvance(phase);
547		// Fall here even if parent waited, to reconcile and help release
548		return untimedWait(phase);
#	Line 541 | Line 550 | public class Phaser {
550
551		/**
552		* Awaits the phase of the barrier to advance from the given
553	<	* value, or returns immediately if argumet is negative or this
553	>	* value, or returns immediately if argument is negative or this
554		* barrier is terminated, or throws InterruptedException if
555		* interrupted while waiting.
556		* @param phase the phase on entry to this method
557		* @return the phase on exit from this method
558		* @throws InterruptedException if thread interrupted while waiting
559		*/
560	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
560	>	public int awaitAdvanceInterruptibly(int phase)
561	>	throws InterruptedException {
562		if (phase < 0)
563		return phase;
564		long s = getReconciledState();
565		int p = phaseOf(s);
566		if (p != phase)
567		return p;
568	<	if (unarrivedOf(s) != 0)
568	>	if (unarrivedOf(s) == 0 && parent != null)
569		parent.awaitAdvanceInterruptibly(phase);
570		return interruptibleWait(phase);
571		}
#	Line 577 | Line 587 | public class Phaser {
587		int p = phaseOf(s);
588		if (p != phase)
589		return p;
590	<	if (unarrivedOf(s) == 0)
590	>	if (unarrivedOf(s) == 0 && parent != null)
591		parent.awaitAdvanceInterruptibly(phase, timeout, unit);
592		return timedWait(phase, unit.toNanos(timeout));
593		}
#	Line 608 | Line 618 | public class Phaser {
618
619		/**
620		* Returns the current phase number. The maximum phase number is
621	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
621	>	* {@code Integer.MAX_VALUE}, after which it restarts at
622		* zero. Upon termination, the phase number is negative.
623		* @return the phase number, or a negative value if terminated
624		*/
#	Line 617 | Line 627 | public class Phaser {
627		}
628
629		/**
630	<	* Returns true if the current phase number equals the given phase.
630	>	* Returns {@code true} if the current phase number equals the given phase.
631		* @param phase the phase
632	<	* @return true if the current phase number equals the given phase.
632	>	* @return {@code true} if the current phase number equals the given phase
633		*/
634		public final boolean hasPhase(int phase) {
635		return phaseOf(getReconciledState()) == phase;
#	Line 653 | Line 663 | public class Phaser {
663
664		/**
665		* Returns the parent of this phaser, or null if none.
666	<	* @return the parent of this phaser, or null if none.
666	>	* @return the parent of this phaser, or null if none
667		*/
668		public Phaser getParent() {
669		return parent;
#	Line 662 | Line 672 | public class Phaser {
672		/**
673		* Returns the root ancestor of this phaser, which is the same as
674		* this phaser if it has no parent.
675	<	* @return the root ancestor of this phaser.
675	>	* @return the root ancestor of this phaser
676		*/
677		public Phaser getRoot() {
678		return root;
679		}
680
681		/**
682	<	* Returns true if this barrier has been terminated.
683	<	* @return true if this barrier has been terminated
682	>	* Returns {@code true} if this barrier has been terminated.
683	>	* @return {@code true} if this barrier has been terminated
684		*/
685		public boolean isTerminated() {
686		return getPhase() < 0;
#	Line 682 | Line 692 | public class Phaser {
692		* barrier is tripped (and thus all other waiting parties are
693		* dormant). If it returns true, then, rather than advance the
694		* phase number, this barrier will be set to a final termination
695	<	* state, and subsequent calls to <tt>isTerminated</tt> will
695	>	* state, and subsequent calls to {@code isTerminated} will
696		* return true.
697		*
698		* <p> The default version returns true when the number of
#	Line 693 | Line 703 | public class Phaser {
703		* <p> You may override this method to perform an action with side
704		* effects visible to participating tasks, but it is in general
705		* only sensible to do so in designs where all parties register
706	<	* before any arrive, and all <tt>awaitAdvance</tt> at each phase.
706	>	* before any arrive, and all {@code awaitAdvance} at each phase.
707		* Otherwise, you cannot ensure lack of interference. In
708		* particular, this method may be invoked more than once per
709		* transition if other parties successfully register while the
#	Line 702 | Line 712 | public class Phaser {
712		* method.
713		*
714		* @param phase the phase number on entering the barrier
715	<	* @param registeredParties the current number of registered
716	<	* parties.
707	<	* @return true if this barrier should terminate
715	>	* @param registeredParties the current number of registered parties
716	>	* @return {@code true} if this barrier should terminate
717		*/
718		protected boolean onAdvance(int phase, int registeredParties) {
719		return registeredParties <= 0;
#	Line 713 | Line 722 | public class Phaser {
722		/**
723		* Returns a string identifying this phaser, as well as its
724		* state.  The state, in brackets, includes the String {@code
725	<	* "phase ="} followed by the phase number, {@code "parties ="}
725	>	* "phase = "} followed by the phase number, {@code "parties = "}
726		* followed by the number of registered parties, and {@code
727	<	* "arrived ="} followed by the number of arrived parties
727	>	* "arrived = "} followed by the number of arrived parties.
728		*
729		* @return a string identifying this barrier, as well as its state
730		*/
731		public String toString() {
732		long s = getReconciledState();
733	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
733	>	return super.toString() +
734	>	"[phase = " + phaseOf(s) +
735	>	" parties = " + partiesOf(s) +
736	>	" arrived = " + arrivedOf(s) + "]";
737		}
738
739		// methods for waiting
740
729	–	/** The number of CPUs, for spin control */
730	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
731	–
732	–	/**
733	–	* The number of times to spin before blocking in timed waits.
734	–	* The value is empirically derived.
735	–	*/
736	–	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
737	–
738	–	/**
739	–	* The number of times to spin before blocking in untimed waits.
740	–	* This is greater than timed value because untimed waits spin
741	–	* faster since they don't need to check times on each spin.
742	–	*/
743	–	static final int maxUntimedSpins = maxTimedSpins * 32;
744	–
741		/**
742	<	* The number of nanoseconds for which it is faster to spin
747	<	* rather than to use timed park. A rough estimate suffices.
742	>	* Wait nodes for Treiber stack representing wait queue
743		*/
744	<	static final long spinForTimeoutThreshold = 1000L;
745	<
746	<	/**
747	<	* Wait nodes for Treiber stack representing wait queue for non-FJ
748	<	* tasks.
749	<	*/
750	<	static final class QNode {
751	<	QNode next;
744	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
745	>	final Phaser phaser;
746	>	final int phase;
747	>	final long startTime;
748	>	final long nanos;
749	>	final boolean timed;
750	>	final boolean interruptible;
751	>	volatile boolean wasInterrupted = false;
752		volatile Thread thread; // nulled to cancel wait
753	<	QNode() {
753	>	QNode next;
754	>	QNode(Phaser phaser, int phase, boolean interruptible,
755	>	boolean timed, long startTime, long nanos) {
756	>	this.phaser = phaser;
757	>	this.phase = phase;
758	>	this.timed = timed;
759	>	this.interruptible = interruptible;
760	>	this.startTime = startTime;
761	>	this.nanos = nanos;
762		thread = Thread.currentThread();
763		}
764	+	public boolean isReleasable() {
765	+	return (thread == null ||
766	+	phaser.getPhase() != phase ||
767	+	(interruptible && wasInterrupted) ||
768	+	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
769	+	}
770	+	public boolean block() {
771	+	if (Thread.interrupted()) {
772	+	wasInterrupted = true;
773	+	if (interruptible)
774	+	return true;
775	+	}
776	+	if (!timed)
777	+	LockSupport.park(this);
778	+	else {
779	+	long waitTime = nanos - (System.nanoTime() - startTime);
780	+	if (waitTime <= 0)
781	+	return true;
782	+	LockSupport.parkNanos(this, waitTime);
783	+	}
784	+	return isReleasable();
785	+	}
786		void signal() {
787		Thread t = thread;
788		if (t != null) {
#	Line 765 | Line 790 | public class Phaser {
790		LockSupport.unpark(t);
791		}
792		}
793	+	boolean doWait() {
794	+	if (thread != null) {
795	+	try {
796	+	ForkJoinPool.managedBlock(this, false);
797	+	} catch (InterruptedException ie) {
798	+	}
799	+	}
800	+	return wasInterrupted;
801	+	}
802	+
803		}
804
805		/**
#	Line 780 | Line 815 | public class Phaser {
815		}
816
817		/**
818	+	* Tries to enqueue given node in the appropriate wait queue
819	+	* @return true if successful
820	+	*/
821	+	private boolean tryEnqueue(QNode node) {
822	+	AtomicReference<QNode> head = queueFor(node.phase);
823	+	return head.compareAndSet(node.next = head.get(), node);
824	+	}
825	+
826	+	/**
827		* Enqueues node and waits unless aborted or signalled.
828	+	* @return current phase
829		*/
830		private int untimedWait(int phase) {
786	–	int spins = maxUntimedSpins;
831		QNode node = null;
788	–	boolean interrupted = false;
832		boolean queued = false;
833	+	boolean interrupted = false;
834		int p;
835		while ((p = getPhase()) == phase) {
836	<	interrupted = Thread.interrupted();
837	<	if (node != null) {
838	<	if (!queued) {
839	<	AtomicReference<QNode> head = queueFor(phase);
840	<	queued = head.compareAndSet(node.next = head.get(), node);
841	<	}
798	<	else if (node.thread != null)
799	<	LockSupport.park(this);
800	<	}
801	<	else if (spins <= 0)
802	<	node = new QNode();
836	>	if (Thread.interrupted())
837	>	interrupted = true;
838	>	else if (node == null)
839	>	node = new QNode(this, phase, false, false, 0, 0);
840	>	else if (!queued)
841	>	queued = tryEnqueue(node);
842		else
843	<	--spins;
843	>	interrupted = node.doWait();
844		}
845		if (node != null)
846		node.thread = null;
847	+	releaseWaiters(phase);
848		if (interrupted)
849		Thread.currentThread().interrupt();
810	–	releaseWaiters(phase);
850		return p;
851		}
852
853		/**
854	<	* Messier interruptible version
854	>	* Interruptible version
855	>	* @return current phase
856		*/
857		private int interruptibleWait(int phase) throws InterruptedException {
818	–	int spins = maxUntimedSpins;
858		QNode node = null;
859		boolean queued = false;
860		boolean interrupted = false;
861		int p;
862	<	while ((p = getPhase()) == phase) {
863	<	if (interrupted = Thread.interrupted())
864	<	break;
865	<	if (node != null) {
866	<	if (!queued) {
867	<	AtomicReference<QNode> head = queueFor(phase);
868	<	queued = head.compareAndSet(node.next = head.get(), node);
830	<	}
831	<	else if (node.thread != null)
832	<	LockSupport.park(this);
833	<	}
834	<	else if (spins <= 0)
835	<	node = new QNode();
862	>	while ((p = getPhase()) == phase && !interrupted) {
863	>	if (Thread.interrupted())
864	>	interrupted = true;
865	>	else if (node == null)
866	>	node = new QNode(this, phase, true, false, 0, 0);
867	>	else if (!queued)
868	>	queued = tryEnqueue(node);
869		else
870	<	--spins;
870	>	interrupted = node.doWait();
871		}
872		if (node != null)
873		node.thread = null;
874	+	if (p != phase || (p = getPhase()) != phase)
875	+	releaseWaiters(phase);
876		if (interrupted)
877		throw new InterruptedException();
843	–	releaseWaiters(phase);
878		return p;
879		}
880
881		/**
882	<	* Even messier timeout version.
882	>	* Timeout version.
883	>	* @return current phase
884		*/
885		private int timedWait(int phase, long nanos)
886		throws InterruptedException, TimeoutException {
887	+	long startTime = System.nanoTime();
888	+	QNode node = null;
889	+	boolean queued = false;
890	+	boolean interrupted = false;
891		int p;
892	<	if ((p = getPhase()) == phase) {
893	<	long lastTime = System.nanoTime();
894	<	int spins = maxTimedSpins;
895	<	QNode node = null;
896	<	boolean queued = false;
897	<	boolean interrupted = false;
898	<	while ((p = getPhase()) == phase) {
899	<	if (interrupted = Thread.interrupted())
900	<	break;
901	<	long now = System.nanoTime();
902	<	if ((nanos -= now - lastTime) <= 0)
864	<	break;
865	<	lastTime = now;
866	<	if (node != null) {
867	<	if (!queued) {
868	<	AtomicReference<QNode> head = queueFor(phase);
869	<	queued = head.compareAndSet(node.next = head.get(), node);
870	<	}
871	<	else if (node.thread != null &&
872	<	nanos > spinForTimeoutThreshold) {
873	<	LockSupport.parkNanos(this, nanos);
874	<	}
875	<	}
876	<	else if (spins <= 0)
877	<	node = new QNode();
878	<	else
879	<	--spins;
880	<	}
881	<	if (node != null)
882	<	node.thread = null;
883	<	if (interrupted)
884	<	throw new InterruptedException();
885	<	if (p == phase && (p = getPhase()) == phase)
886	<	throw new TimeoutException();
892	>	while ((p = getPhase()) == phase && !interrupted) {
893	>	if (Thread.interrupted())
894	>	interrupted = true;
895	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
896	>	break;
897	>	else if (node == null)
898	>	node = new QNode(this, phase, true, true, startTime, nanos);
899	>	else if (!queued)
900	>	queued = tryEnqueue(node);
901	>	else
902	>	interrupted = node.doWait();
903		}
904	<	releaseWaiters(phase);
904	>	if (node != null)
905	>	node.thread = null;
906	>	if (p != phase || (p = getPhase()) != phase)
907	>	releaseWaiters(phase);
908	>	if (interrupted)
909	>	throw new InterruptedException();
910	>	if (p == phase)
911	>	throw new TimeoutException();
912		return p;
913		}
914
915		// Temporary Unsafe mechanics for preliminary release
916	+	private static Unsafe getUnsafe() throws Throwable {
917	+	try {
918	+	return Unsafe.getUnsafe();
919	+	} catch (SecurityException se) {
920	+	try {
921	+	return java.security.AccessController.doPrivileged
922	+	(new java.security.PrivilegedExceptionAction<Unsafe>() {
923	+	public Unsafe run() throws Exception {
924	+	return getUnsafePrivileged();
925	+	}});
926	+	} catch (java.security.PrivilegedActionException e) {
927	+	throw e.getCause();
928	+	}
929	+	}
930	+	}
931	+
932	+	private static Unsafe getUnsafePrivileged()
933	+	throws NoSuchFieldException, IllegalAccessException {
934	+	Field f = Unsafe.class.getDeclaredField("theUnsafe");
935	+	f.setAccessible(true);
936	+	return (Unsafe)f.get(null);
937	+	}
938	+
939	+	private static long fieldOffset(String fieldName)
940	+	throws NoSuchFieldException {
941	+	return _unsafe.objectFieldOffset
942	+	(Phaser.class.getDeclaredField(fieldName));
943	+	}
944
945		static final Unsafe _unsafe;
946		static final long stateOffset;
947
948		static {
949		try {
950	<	if (Phaser.class.getClassLoader() != null) {
951	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
901	<	f.setAccessible(true);
902	<	_unsafe = (Unsafe)f.get(null);
903	<	}
904	<	else
905	<	_unsafe = Unsafe.getUnsafe();
906	<	stateOffset = _unsafe.objectFieldOffset
907	<	(Phaser.class.getDeclaredField("state"));
950	>	_unsafe = getUnsafe();
951	>	stateOffset = fieldOffset("state");
952		} catch (Exception e) {
953		throw new RuntimeException("Could not initialize intrinsics", e);
954		}

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