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Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.5 by dl, Sun Sep 7 11:24:26 2008 UTC vs.
Revision 1.13 by jsr166, Mon Jul 20 22:40:09 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:
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();
111		*   phaser.arrive(); // allow threads to start
112	<	*   int p = phaser.arriveAndDeregister(); // deregister self
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); // wait for all tasks to arrive
116	<	* }
110	<	* </pre>
115	>	*   phaser.awaitAdvance(p); // await final completion
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 <tt>onAdvance</tt>:
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	<	*    };
122	<	*    phaser.register();
123	<	*    for (Runnable r : list) {
124	<	*      phaser.register();
125	<	*      new Thread() {
126	<	*        public void run() {
127	<	*           do {
128	<	*             r.run();
129	<	*             phaser.arriveAndAwaitAdvance();
130	<	*           } while(!phaser.isTerminated();
131	<	*        }
132	<	*      }.start();
138	>	*     }.start();
139		*   }
140		*   phaser.arriveAndDeregister(); // deregister self, don't wait
141	<	* }
136	<	* </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
160	<	*  build(new Task[n], 0, n, new Phaser());
161	<	* </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 <tt>TASKS_PER_PHASER</tt> depends mainly on
166	>	* The best value of {@code TASKS_PER_PHASER} depends mainly on
167		* expected barrier synchronization rates. A value as low as four may
168		* be appropriate for extremely small per-barrier task bodies (thus
169		* high rates), or up to hundreds for extremely large ones.
#	Line 192 | Line 195 | public class Phaser {
195		* However, to efficiently maintain atomicity, these values are
196		* packed into a single (atomic) long. Termination uses the sign
197		* bit of 32 bit representation of phase, so phase is set to -1 on
198	<	* termination. Good performace relies on keeping state decoding
198	>	* termination. Good performance relies on keeping state decoding
199		* and encoding simple, and keeping race windows short.
200		*
201		* Note: there are some cheats in arrive() that rely on unarrived
202	<	* being lowest 16 bits.
202	>	* count being lowest 16 bits.
203		*/
204		private volatile long state;
205
206		private static final int ushortBits = 16;
207	<	private static final int ushortMask =  (1 << ushortBits) - 1;
208	<	private static final int phaseMask = 0x7fffffff;
207	>	private static final int ushortMask = 0xffff;
208	>	private static final int phaseMask  = 0x7fffffff;
209
210		private static int unarrivedOf(long s) {
211		return (int)(s & ushortMask);
212		}
213
214		private static int partiesOf(long s) {
215	<	return (int)(s & (ushortMask << 16)) >>> 16;
215	>	return ((int)s) >>> 16;
216		}
217
218		private static int phaseOf(long s) {
#	Line 221 | Line 224 | public class Phaser {
224		}
225
226		private static long stateFor(int phase, int parties, int unarrived) {
227	<	return (((long)phase) << 32) | ((parties << 16) | unarrived);
227	>	return ((((long)phase) << 32) | (((long)parties) << 16) |
228	>	(long)unarrived);
229		}
230
231		private static long trippedStateFor(int phase, int parties) {
232	<	return (((long)phase) << 32) | ((parties << 16) | parties);
232	>	long lp = (long)parties;
233	>	return (((long)phase) << 32) | (lp << 16) | lp;
234		}
235
236	<	private static IllegalStateException badBounds(int parties, int unarrived) {
237	<	return new IllegalStateException
238	<	("Attempt to set " + unarrived +
239	<	" unarrived of " + parties + " parties");
236	>	/**
237	>	* Returns message string for bad bounds exceptions
238	>	*/
239	>	private static String badBounds(int parties, int unarrived) {
240	>	return ("Attempt to set " + unarrived +
241	>	" unarrived of " + parties + " parties");
242		}
243
244		/**
#	Line 248 | Line 255 | public class Phaser {
255		// Wait queues
256
257		/**
258	<	* Heads of Treiber stacks waiting for nonFJ threads. To eliminate
258	>	* Heads of Treiber stacks for waiting threads. To eliminate
259		* contention while releasing some threads while adding others, we
260		* use two of them, alternating across even and odd phases.
261		*/
#	Line 292 | Line 299 | public class Phaser {
299
300		/**
301		* Creates a new Phaser without any initially registered parties,
302	<	* initial phase number 0, and no parent.
302	>	* initial phase number 0, and no parent. Any thread using this
303	>	* Phaser will need to first register for it.
304		*/
305		public Phaser() {
306		this(null);
#	Line 390 | Line 398 | public class Phaser {
398		if (phase < 0)
399		break;
400		if (parties > ushortMask || unarrived > ushortMask)
401	<	throw badBounds(parties, unarrived);
401	>	throw new IllegalStateException(badBounds(parties, unarrived));
402		if (phase == phaseOf(root.state) &&
403		casState(s, stateFor(phase, parties, unarrived)))
404		break;
#	Line 412 | Line 420 | public class Phaser {
420		for (;;) {
421		long s = state;
422		phase = phaseOf(s);
423	+	if (phase < 0)
424	+	break;
425		int parties = partiesOf(s);
426		int unarrived = unarrivedOf(s) - 1;
427		if (unarrived > 0) {        // Not the last arrival
#	Line 437 | Line 447 | public class Phaser {
447		}
448		}
449		}
440	–	else if (phase < 0) // Don't throw exception if terminated
441	–	break;
450		else if (phase != phaseOf(root.state)) // or if unreconciled
451		reconcileState();
452		else
453	<	throw badBounds(parties, unarrived);
453	>	throw new IllegalStateException(badBounds(parties, unarrived));
454		}
455		return phase;
456		}
#	Line 466 | Line 474 | public class Phaser {
474		for (;;) {
475		long s = state;
476		phase = phaseOf(s);
477	+	if (phase < 0)
478	+	break;
479		int parties = partiesOf(s) - 1;
480		int unarrived = unarrivedOf(s) - 1;
481		if (parties >= 0) {
#	Line 491 | Line 501 | public class Phaser {
501		}
502		continue;
503		}
494	–	if (phase < 0)
495	–	break;
504		if (par != null && phase != phaseOf(root.state)) {
505		reconcileState();
506		continue;
507		}
508		}
509	<	throw badBounds(parties, unarrived);
509	>	throw new IllegalStateException(badBounds(parties, unarrived));
510		}
511		return phase;
512		}
513
514		/**
515		* Arrives at the barrier and awaits others. Equivalent in effect
516	<	* to <tt>awaitAdvance(arrive())</tt>.  If you instead need to
516	>	* to {@code awaitAdvance(arrive())}.  If you instead need to
517		* await with interruption of timeout, and/or deregister upon
518		* arrival, you can arrange them using analogous constructions.
519		* @return the phase on entry to this method
#	Line 530 | Line 538 | public class Phaser {
538		int p = phaseOf(s);
539		if (p != phase)
540		return p;
541	<	if (unarrivedOf(s) == 0)
541	>	if (unarrivedOf(s) == 0 && parent != null)
542		parent.awaitAdvance(phase);
543		// Fall here even if parent waited, to reconcile and help release
544		return untimedWait(phase);
#	Line 538 | Line 546 | public class Phaser {
546
547		/**
548		* Awaits the phase of the barrier to advance from the given
549	<	* value, or returns immediately if argumet is negative or this
549	>	* value, or returns immediately if argument is negative or this
550		* barrier is terminated, or throws InterruptedException if
551		* interrupted while waiting.
552		* @param phase the phase on entry to this method
553		* @return the phase on exit from this method
554		* @throws InterruptedException if thread interrupted while waiting
555		*/
556	<	public int awaitAdvanceInterruptibly(int phase) throws InterruptedException {
556	>	public int awaitAdvanceInterruptibly(int phase)
557	>	throws InterruptedException {
558		if (phase < 0)
559		return phase;
560		long s = getReconciledState();
561		int p = phaseOf(s);
562		if (p != phase)
563		return p;
564	<	if (unarrivedOf(s) != 0)
564	>	if (unarrivedOf(s) == 0 && parent != null)
565		parent.awaitAdvanceInterruptibly(phase);
566		return interruptibleWait(phase);
567		}
#	Line 574 | Line 583 | public class Phaser {
583		int p = phaseOf(s);
584		if (p != phase)
585		return p;
586	<	if (unarrivedOf(s) == 0)
586	>	if (unarrivedOf(s) == 0 && parent != null)
587		parent.awaitAdvanceInterruptibly(phase, timeout, unit);
588		return timedWait(phase, unit.toNanos(timeout));
589		}
#	Line 605 | Line 614 | public class Phaser {
614
615		/**
616		* Returns the current phase number. The maximum phase number is
617	<	* <tt>Integer.MAX_VALUE</tt>, after which it restarts at
617	>	* {@code Integer.MAX_VALUE}, after which it restarts at
618		* zero. Upon termination, the phase number is negative.
619		* @return the phase number, or a negative value if terminated
620		*/
#	Line 614 | Line 623 | public class Phaser {
623		}
624
625		/**
626	<	* Returns true if the current phase number equals the given phase.
626	>	* Returns {@code true} if the current phase number equals the given phase.
627		* @param phase the phase
628	<	* @return true if the current phase number equals the given phase.
628	>	* @return {@code true} if the current phase number equals the given phase
629		*/
630		public final boolean hasPhase(int phase) {
631		return phaseOf(getReconciledState()) == phase;
#	Line 650 | Line 659 | public class Phaser {
659
660		/**
661		* Returns the parent of this phaser, or null if none.
662	<	* @return the parent of this phaser, or null if none.
662	>	* @return the parent of this phaser, or null if none
663		*/
664		public Phaser getParent() {
665		return parent;
#	Line 659 | Line 668 | public class Phaser {
668		/**
669		* Returns the root ancestor of this phaser, which is the same as
670		* this phaser if it has no parent.
671	<	* @return the root ancestor of this phaser.
671	>	* @return the root ancestor of this phaser
672		*/
673		public Phaser getRoot() {
674		return root;
675		}
676
677		/**
678	<	* Returns true if this barrier has been terminated.
679	<	* @return true if this barrier has been terminated
678	>	* Returns {@code true} if this barrier has been terminated.
679	>	* @return {@code true} if this barrier has been terminated
680		*/
681		public boolean isTerminated() {
682		return getPhase() < 0;
#	Line 679 | Line 688 | public class Phaser {
688		* barrier is tripped (and thus all other waiting parties are
689		* dormant). If it returns true, then, rather than advance the
690		* phase number, this barrier will be set to a final termination
691	<	* state, and subsequent calls to <tt>isTerminated</tt> will
691	>	* state, and subsequent calls to {@code isTerminated} will
692		* return true.
693		*
694		* <p> The default version returns true when the number of
#	Line 690 | Line 699 | public class Phaser {
699		* <p> You may override this method to perform an action with side
700		* effects visible to participating tasks, but it is in general
701		* only sensible to do so in designs where all parties register
702	<	* before any arrive, and all <tt>awaitAdvance</tt> at each phase.
702	>	* before any arrive, and all {@code awaitAdvance} at each phase.
703		* Otherwise, you cannot ensure lack of interference. In
704		* particular, this method may be invoked more than once per
705		* transition if other parties successfully register while the
#	Line 699 | Line 708 | public class Phaser {
708		* method.
709		*
710		* @param phase the phase number on entering the barrier
711	<	* @param registeredParties the current number of registered
712	<	* parties.
704	<	* @return true if this barrier should terminate
711	>	* @param registeredParties the current number of registered parties
712	>	* @return {@code true} if this barrier should terminate
713		*/
714		protected boolean onAdvance(int phase, int registeredParties) {
715		return registeredParties <= 0;
#	Line 710 | Line 718 | public class Phaser {
718		/**
719		* Returns a string identifying this phaser, as well as its
720		* state.  The state, in brackets, includes the String {@code
721	<	* "phase ="} followed by the phase number, {@code "parties ="}
721	>	* "phase = "} followed by the phase number, {@code "parties = "}
722		* followed by the number of registered parties, and {@code
723	<	* "arrived ="} followed by the number of arrived parties
723	>	* "arrived = "} followed by the number of arrived parties.
724		*
725		* @return a string identifying this barrier, as well as its state
726		*/
727		public String toString() {
728		long s = getReconciledState();
729	<	return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]";
729	>	return super.toString() +
730	>	"[phase = " + phaseOf(s) +
731	>	" parties = " + partiesOf(s) +
732	>	" arrived = " + arrivedOf(s) + "]";
733		}
734
735		// methods for waiting
736
726	–	/** The number of CPUs, for spin control */
727	–	static final int NCPUS = Runtime.getRuntime().availableProcessors();
728	–
729	–	/**
730	–	* The number of times to spin before blocking in timed waits.
731	–	* The value is empirically derived.
732	–	*/
733	–	static final int maxTimedSpins = (NCPUS < 2)? 0 : 32;
734	–
735	–	/**
736	–	* The number of times to spin before blocking in untimed waits.
737	–	* This is greater than timed value because untimed waits spin
738	–	* faster since they don't need to check times on each spin.
739	–	*/
740	–	static final int maxUntimedSpins = maxTimedSpins * 32;
741	–
742	–	/**
743	–	* The number of nanoseconds for which it is faster to spin
744	–	* rather than to use timed park. A rough estimate suffices.
745	–	*/
746	–	static final long spinForTimeoutThreshold = 1000L;
747	–
737		/**
738	<	* Wait nodes for Treiber stack representing wait queue for non-FJ
750	<	* tasks.
738	>	* Wait nodes for Treiber stack representing wait queue
739		*/
740	<	static final class QNode {
741	<	QNode next;
740	>	static final class QNode implements ForkJoinPool.ManagedBlocker {
741	>	final Phaser phaser;
742	>	final int phase;
743	>	final long startTime;
744	>	final long nanos;
745	>	final boolean timed;
746	>	final boolean interruptible;
747	>	volatile boolean wasInterrupted = false;
748		volatile Thread thread; // nulled to cancel wait
749	<	QNode() {
749	>	QNode next;
750	>	QNode(Phaser phaser, int phase, boolean interruptible,
751	>	boolean timed, long startTime, long nanos) {
752	>	this.phaser = phaser;
753	>	this.phase = phase;
754	>	this.timed = timed;
755	>	this.interruptible = interruptible;
756	>	this.startTime = startTime;
757	>	this.nanos = nanos;
758		thread = Thread.currentThread();
759		}
760	+	public boolean isReleasable() {
761	+	return (thread == null ||
762	+	phaser.getPhase() != phase ||
763	+	(interruptible && wasInterrupted) ||
764	+	(timed && (nanos - (System.nanoTime() - startTime)) <= 0));
765	+	}
766	+	public boolean block() {
767	+	if (Thread.interrupted()) {
768	+	wasInterrupted = true;
769	+	if (interruptible)
770	+	return true;
771	+	}
772	+	if (!timed)
773	+	LockSupport.park(this);
774	+	else {
775	+	long waitTime = nanos - (System.nanoTime() - startTime);
776	+	if (waitTime <= 0)
777	+	return true;
778	+	LockSupport.parkNanos(this, waitTime);
779	+	}
780	+	return isReleasable();
781	+	}
782		void signal() {
783		Thread t = thread;
784		if (t != null) {
#	Line 762 | Line 786 | public class Phaser {
786		LockSupport.unpark(t);
787		}
788		}
789	+	boolean doWait() {
790	+	if (thread != null) {
791	+	try {
792	+	ForkJoinPool.managedBlock(this, false);
793	+	} catch (InterruptedException ie) {
794	+	}
795	+	}
796	+	return wasInterrupted;
797	+	}
798	+
799		}
800
801		/**
#	Line 777 | Line 811 | public class Phaser {
811		}
812
813		/**
814	+	* Tries to enqueue given node in the appropriate wait queue
815	+	* @return true if successful
816	+	*/
817	+	private boolean tryEnqueue(QNode node) {
818	+	AtomicReference<QNode> head = queueFor(node.phase);
819	+	return head.compareAndSet(node.next = head.get(), node);
820	+	}
821	+
822	+	/**
823		* Enqueues node and waits unless aborted or signalled.
824	+	* @return current phase
825		*/
826		private int untimedWait(int phase) {
783	–	int spins = maxUntimedSpins;
827		QNode node = null;
785	–	boolean interrupted = false;
828		boolean queued = false;
829	+	boolean interrupted = false;
830		int p;
831		while ((p = getPhase()) == phase) {
832	<	interrupted = Thread.interrupted();
833	<	if (node != null) {
834	<	if (!queued) {
835	<	AtomicReference<QNode> head = queueFor(phase);
836	<	queued = head.compareAndSet(node.next = head.get(), node);
837	<	}
795	<	else if (node.thread != null)
796	<	LockSupport.park(this);
797	<	}
798	<	else if (spins <= 0)
799	<	node = new QNode();
832	>	if (Thread.interrupted())
833	>	interrupted = true;
834	>	else if (node == null)
835	>	node = new QNode(this, phase, false, false, 0, 0);
836	>	else if (!queued)
837	>	queued = tryEnqueue(node);
838		else
839	<	--spins;
839	>	interrupted = node.doWait();
840		}
841		if (node != null)
842		node.thread = null;
843	+	releaseWaiters(phase);
844		if (interrupted)
845		Thread.currentThread().interrupt();
807	–	releaseWaiters(phase);
846		return p;
847		}
848
849		/**
850	<	* Messier interruptible version
850	>	* Interruptible version
851	>	* @return current phase
852		*/
853		private int interruptibleWait(int phase) throws InterruptedException {
815	–	int spins = maxUntimedSpins;
854		QNode node = null;
855		boolean queued = false;
856		boolean interrupted = false;
857		int p;
858	<	while ((p = getPhase()) == phase) {
859	<	if (interrupted = Thread.interrupted())
860	<	break;
861	<	if (node != null) {
862	<	if (!queued) {
863	<	AtomicReference<QNode> head = queueFor(phase);
864	<	queued = head.compareAndSet(node.next = head.get(), node);
827	<	}
828	<	else if (node.thread != null)
829	<	LockSupport.park(this);
830	<	}
831	<	else if (spins <= 0)
832	<	node = new QNode();
858	>	while ((p = getPhase()) == phase && !interrupted) {
859	>	if (Thread.interrupted())
860	>	interrupted = true;
861	>	else if (node == null)
862	>	node = new QNode(this, phase, true, false, 0, 0);
863	>	else if (!queued)
864	>	queued = tryEnqueue(node);
865		else
866	<	--spins;
866	>	interrupted = node.doWait();
867		}
868		if (node != null)
869		node.thread = null;
870	+	if (p != phase || (p = getPhase()) != phase)
871	+	releaseWaiters(phase);
872		if (interrupted)
873		throw new InterruptedException();
840	–	releaseWaiters(phase);
874		return p;
875		}
876
877		/**
878	<	* Even messier timeout version.
878	>	* Timeout version.
879	>	* @return current phase
880		*/
881		private int timedWait(int phase, long nanos)
882		throws InterruptedException, TimeoutException {
883	+	long startTime = System.nanoTime();
884	+	QNode node = null;
885	+	boolean queued = false;
886	+	boolean interrupted = false;
887		int p;
888	<	if ((p = getPhase()) == phase) {
889	<	long lastTime = System.nanoTime();
890	<	int spins = maxTimedSpins;
891	<	QNode node = null;
892	<	boolean queued = false;
893	<	boolean interrupted = false;
894	<	while ((p = getPhase()) == phase) {
895	<	if (interrupted = Thread.interrupted())
896	<	break;
897	<	long now = System.nanoTime();
898	<	if ((nanos -= now - lastTime) <= 0)
861	<	break;
862	<	lastTime = now;
863	<	if (node != null) {
864	<	if (!queued) {
865	<	AtomicReference<QNode> head = queueFor(phase);
866	<	queued = head.compareAndSet(node.next = head.get(), node);
867	<	}
868	<	else if (node.thread != null &&
869	<	nanos > spinForTimeoutThreshold) {
870	<	LockSupport.parkNanos(this, nanos);
871	<	}
872	<	}
873	<	else if (spins <= 0)
874	<	node = new QNode();
875	<	else
876	<	--spins;
877	<	}
878	<	if (node != null)
879	<	node.thread = null;
880	<	if (interrupted)
881	<	throw new InterruptedException();
882	<	if (p == phase && (p = getPhase()) == phase)
883	<	throw new TimeoutException();
888	>	while ((p = getPhase()) == phase && !interrupted) {
889	>	if (Thread.interrupted())
890	>	interrupted = true;
891	>	else if (nanos - (System.nanoTime() - startTime) <= 0)
892	>	break;
893	>	else if (node == null)
894	>	node = new QNode(this, phase, true, true, startTime, nanos);
895	>	else if (!queued)
896	>	queued = tryEnqueue(node);
897	>	else
898	>	interrupted = node.doWait();
899		}
900	<	releaseWaiters(phase);
900	>	if (node != null)
901	>	node.thread = null;
902	>	if (p != phase || (p = getPhase()) != phase)
903	>	releaseWaiters(phase);
904	>	if (interrupted)
905	>	throw new InterruptedException();
906	>	if (p == phase)
907	>	throw new TimeoutException();
908		return p;
909		}
910
911		// Temporary Unsafe mechanics for preliminary release
912	+	private static Unsafe getUnsafe() throws Throwable {
913	+	try {
914	+	return Unsafe.getUnsafe();
915	+	} catch (SecurityException se) {
916	+	try {
917	+	return java.security.AccessController.doPrivileged
918	+	(new java.security.PrivilegedExceptionAction<Unsafe>() {
919	+	public Unsafe run() throws Exception {
920	+	return getUnsafePrivileged();
921	+	}});
922	+	} catch (java.security.PrivilegedActionException e) {
923	+	throw e.getCause();
924	+	}
925	+	}
926	+	}
927	+
928	+	private static Unsafe getUnsafePrivileged()
929	+	throws NoSuchFieldException, IllegalAccessException {
930	+	Field f = Unsafe.class.getDeclaredField("theUnsafe");
931	+	f.setAccessible(true);
932	+	return (Unsafe) f.get(null);
933	+	}
934	+
935	+	private static long fieldOffset(String fieldName)
936	+	throws NoSuchFieldException {
937	+	return _unsafe.objectFieldOffset
938	+	(Phaser.class.getDeclaredField(fieldName));
939	+	}
940
941		static final Unsafe _unsafe;
942		static final long stateOffset;
943
944		static {
945		try {
946	<	if (Phaser.class.getClassLoader() != null) {
947	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
948	<	f.setAccessible(true);
899	<	_unsafe = (Unsafe)f.get(null);
900	<	}
901	<	else
902	<	_unsafe = Unsafe.getUnsafe();
903	<	stateOffset = _unsafe.objectFieldOffset
904	<	(Phaser.class.getDeclaredField("state"));
905	<	} catch (Exception e) {
946	>	_unsafe = getUnsafe();
947	>	stateOffset = fieldOffset("state");
948	>	} catch (Throwable e) {
949		throw new RuntimeException("Could not initialize intrinsics", e);
950		}
951		}

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