[ViewVC] Diff of: jsr166/jsr166/src/jsr166y/Phaser.java

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.12 by jsr166, Thu Mar 19 05:10:42 2009 UTC vs.
Revision 1.35 by dl, Sun Aug 23 13:37:08 2009 UTC

#	Line 7 \| Line 7
7		package jsr166y;
8
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.atomic.*;
10	>
11	>	import java.util.concurrent.atomic.AtomicReference;
12		import java.util.concurrent.locks.LockSupport;
12	–	import sun.misc.Unsafe;
13	–	import java.lang.reflect.*;
13
14		/**
15		* A reusable synchronization barrier, similar in functionality to a
#	Line 20 \| Line 19 \| *import java.lang.reflect.;**
19		*
20		* <ul>
21		*
22	<	* <li> The number of parties synchronizing on a phaser may vary over
23	<	* time. A task may register to be a party at any time, and may
24	<	* deregister upon arriving at the barrier. As is the case with most
25	<	* basic synchronization constructs, registration and deregistration
26	<	* affect only internal counts; they do not establish any further
27	<	* internal bookkeeping, so tasks cannot query whether they are
22	>	* <li> The number of parties <em>registered</em> to synchronize on a
23	>	* phaser may vary over time. Tasks may be registered at any time
24	>	* (using methods {@link #register}, {@link #bulkRegister}, or forms
25	>	* of constructors establishing initial numbers of parties), and may
26	>	* optionally be deregistered upon any arrival (using {@link
27	>	* #arriveAndDeregister}). As is the case with most basic
28	>	* synchronization constructs, registration and deregistration affect
29	>	* only internal counts; they do not establish any further internal
30	>	* bookkeeping, so tasks cannot query whether they are
31		* registered. (However, you can introduce such bookkeeping by
32		* subclassing this class.)
33		*
34		* <li> Each generation has an associated phase value, starting at
35	<	* zero, and advancing when all parties reach the barrier (wrapping
36	<	* around to zero after reaching {@code Integer.MAX_VALUE}).
35	>	* zero, and advancing when all parties arrive at the barrier
36	>	* (wrapping around to zero after reaching {@code Integer.MAX_VALUE}).
37		*
38	<	* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited.
39	<	* Method {@code arriveAndAwaitAdvance} has effect analogous to
40	<	* {@code CyclicBarrier.await}. However, Phasers separate two
41	<	* aspects of coordination, that may also be invoked independently:
38	>	* <li> Like a {@code CyclicBarrier}, a phaser may be repeatedly
39	>	* awaited. Method {@link #arriveAndAwaitAdvance} has effect
40	>	* analogous to {@link java.util.concurrent.CyclicBarrier#await
41	>	* CyclicBarrier.await}. However, phasers separate two aspects of
42	>	* coordination, which may also be invoked independently:
43		*
44		* <ul>
45		*
46	<	* <li> Arriving at a barrier. Methods {@code arrive} and
47	<	* {@code arriveAndDeregister} do not block, but return
48	<	* the phase value current upon entry to the method.
49	<	*
50	<	* <li> Awaiting others. Method {@code awaitAdvance} requires an
51	<	* argument indicating the entry phase, and returns when the
52	<	* barrier advances to a new phase.
46	>	* <li> Arriving at a barrier. Methods {@link #arrive} and
47	>	* {@link #arriveAndDeregister} do not block, but return
48	>	* an associated <em>arrival phase number</em>;
49	>	* that is, the phase number of the barrier to which the
50	>	* arrival applied.
51	>	*
52	>	* <li> Awaiting others. Method {@link #awaitAdvance} requires an
53	>	* argument indicating an arrival phase number, and returns
54	>	* when the barrier advances to a new phase.
55		* </ul>
56		*
57		*
58		* <li> Barrier actions, performed by the task triggering a phase
59	<	* advance while others may be waiting, are arranged by overriding
60	<	* method {@code onAdvance}, that also controls termination.
61	<	* Overriding this method may be used to similar but more flexible
62	<	* effect as providing a barrier action to a CyclicBarrier.
59	>	* advance, are arranged by overriding method {@link #onAdvance(int,
60	>	* int)}, which also controls termination. Overriding this method is
61	>	* similar to, but more flexible than, providing a barrier action to a
62	>	* {@code CyclicBarrier}.
63		*
64		* <li> Phasers may enter a <em>termination</em> state in which all
65		* actions immediately return without updating phaser state or waiting
66		* for advance, and indicating (via a negative phase value) that
67	<	* execution is complete. Termination is triggered by executing the
68	<	* overridable {@code onAdvance} method that is invoked each time the
69	<	* barrier is about to be tripped. When a Phaser is controlling an
70	<	* action with a fixed number of iterations, it is often convenient to
71	<	* override this method to cause termination when the current phase
72	<	* number reaches a threshold. Method {@code forceTermination} is also
73	<	* available to abruptly release waiting threads and allow them to
69	<	* terminate.
67	>	* execution is complete. Termination is triggered when an invocation
68	>	* of {@code onAdvance} returns {@code true}. When a phaser is
69	>	* controlling an action with a fixed number of iterations, it is
70	>	* often convenient to override this method to cause termination when
71	>	* the current phase number reaches a threshold. Method {@link
72	>	* #forceTermination} is also available to abruptly release waiting
73	>	* threads and allow them to terminate.
74		*
75		* <li> Phasers may be tiered to reduce contention. Phasers with large
76		* numbers of parties that would otherwise experience heavy
#	Line 76 \| Line 80 \| *import java.lang.reflect.;**
80		*
81		* <li> By default, {@code awaitAdvance} continues to wait even if
82		* the waiting thread is interrupted. And unlike the case in
83	<	* CyclicBarriers, exceptions encountered while tasks wait
83	>	* {@code CyclicBarrier}, exceptions encountered while tasks wait
84		* interruptibly or with timeout do not change the state of the
85		* barrier. If necessary, you can perform any associated recovery
86		* within handlers of those exceptions, often after invoking
87		* {@code forceTermination}.
88		*
89	<	* <li>Phasers ensure lack of starvation when used by ForkJoinTasks.
89	>	* <li>Phasers may be used to coordinate tasks executing in a {@link
90	>	* ForkJoinPool}, which will ensure sufficient parallelism to execute
91	>	* tasks when others are blocked waiting for a phase to advance.
92		*
93		* </ul>
94		*
95		* <p><b>Sample usages:</b>
96		*
97	<	* <p>A Phaser may be used instead of a {@code CountDownLatch} to control
98	<	* a one-shot action serving a variable number of parties. The typical
99	<	* idiom is for the method setting this up to first register, then
100	<	* start the actions, then deregister, as in:
101	<	*
102	<	* <pre>
103	<	* void runTasks(List<Runnable> list) {
104	<	* final Phaser phaser = new Phaser(1); // "1" to register self
105	<	* for (Runnable r : list) {
106	<	* phaser.register();
107	<	* new Thread() {
108	<	* public void run() {
109	<	* phaser.arriveAndAwaitAdvance(); // await all creation
110	<	* r.run();
111	<	* phaser.arriveAndDeregister(); // signal completion
112	<	* }
113	<	* }.start();
97	>	* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch}
98	>	* to control a one-shot action serving a variable number of
99	>	* parties. The typical idiom is for the method setting this up to
100	>	* first register, then start the actions, then deregister, as in:
101	>	*
102	>	* <pre> {@code
103	>	* void runTasks(List<Runnable> tasks) {
104	>	* final Phaser phaser = new Phaser(1); // "1" to register self
105	>	* // create and start threads
106	>	* for (Runnable task : tasks) {
107	>	* phaser.register();
108	>	* new Thread() {
109	>	* public void run() {
110	>	* phaser.arriveAndAwaitAdvance(); // await all creation
111	>	* task.run();
112	>	* }
113	>	* }.start();
114		* }
115		*
116	<	* doSomethingOnBehalfOfWorkers();
117	<	* phaser.arrive(); // allow threads to start
118	<	* 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); // await final completion
116	<	* }
117	<	* </pre>
116	>	* // allow threads to start and deregister self
117	>	* phaser.arriveAndDeregister();
118	>	* }}</pre>
119		*
120		* <p>One way to cause a set of threads to repeatedly perform actions
121		* for a given number of iterations is to override {@code onAdvance}:
122		*
123	<	* <pre>
124	<	* void startTasks(List<Runnable> list, final int iterations) {
125	<	* final Phaser phaser = new Phaser() {
126	<	* public boolean onAdvance(int phase, int registeredParties) {
127	<	* return phase >= iterations \|\| registeredParties == 0;
123	>	* <pre> {@code
124	>	* void startTasks(List<Runnable> tasks, final int iterations) {
125	>	* final Phaser phaser = new Phaser() {
126	>	* public boolean onAdvance(int phase, int registeredParties) {
127	>	* return phase >= iterations \|\| registeredParties == 0;
128	>	* }
129	>	* };
130	>	* phaser.register();
131	>	* for (Runnable task : tasks) {
132	>	* phaser.register();
133	>	* new Thread() {
134	>	* public void run() {
135	>	* do {
136	>	* task.run();
137	>	* phaser.arriveAndAwaitAdvance();
138	>	* } while(!phaser.isTerminated();
139		* }
140	<	* };
129	<	* phaser.register();
130	<	* for (Runnable r : list) {
131	<	* phaser.register();
132	<	* new Thread() {
133	<	* public void run() {
134	<	* do {
135	<	* r.run();
136	<	* phaser.arriveAndAwaitAdvance();
137	<	* } while(!phaser.isTerminated();
138	<	* }
139	<	* }.start();
140	>	* }.start();
141		* }
142		* phaser.arriveAndDeregister(); // deregister self, don't wait
143	<	* }
143	<	* </pre>
143	>	* }}</pre>
144		*
145	<	* <p> To create a set of tasks using a tree of Phasers,
145	>	* <p>To create a set of tasks using a tree of phasers,
146		* you could use code of the following form, assuming a
147	<	* Task class with a constructor accepting a Phaser that
147	>	* Task class with a constructor accepting a phaser that
148		* it registers for upon construction:
149	<	* <pre>
150	<	* void build(Task[] actions, int lo, int hi, Phaser b) {
151	<	* int step = (hi - lo) / TASKS_PER_PHASER;
152	<	* if (step > 1) {
153	<	* int i = lo;
154	<	* while (i < hi) {
155	<	* int r = Math.min(i + step, hi);
156	<	* build(actions, i, r, new Phaser(b));
157	<	* i = r;
158	<	* }
159	<	* }
160	<	* else {
161	<	* for (int i = lo; i < hi; ++i)
162	<	* actions[i] = new Task(b);
163	<	* // assumes new Task(b) performs b.register()
164	<	* }
165	<	* }
166	<	* // .. initially called, for n tasks via
167	<	* build(new Task[n], 0, n, new Phaser());
168	<	* </pre>
149	>	* <pre> {@code
150	>	* void build(Task[] actions, int lo, int hi, Phaser b) {
151	>	* int step = (hi - lo) / TASKS_PER_PHASER;
152	>	* if (step > 1) {
153	>	* int i = lo;
154	>	* while (i < hi) {
155	>	* int r = Math.min(i + step, hi);
156	>	* build(actions, i, r, new Phaser(b));
157	>	* i = r;
158	>	* }
159	>	* } else {
160	>	* for (int i = lo; i < hi; ++i)
161	>	* actions[i] = new Task(b);
162	>	* // assumes new Task(b) performs b.register()
163	>	* }
164	>	* }
165	>	* // .. initially called, for n tasks via
166	>	* build(new Task[n], 0, n, new Phaser());}</pre>
167		*
168		* The best value of {@code TASKS_PER_PHASER} depends mainly on
169		* expected barrier synchronization rates. A value as low as four may
#	Line 176 \| Line 174 \| *import java.lang.reflect.;**
174		*
175		* <p><b>Implementation notes</b>: This implementation restricts the
176		* maximum number of parties to 65535. Attempts to register additional
177	<	* parties result in IllegalStateExceptions. However, you can and
177	>	* parties result in {@code IllegalStateException}. However, you can and
178		* should create tiered phasers to accommodate arbitrarily large sets
179		* of participants.
180	+	*
181	+	* @since 1.7
182	+	* @author Doug Lea
183		*/
184		public class Phaser {
185		/*
#	Line 212 \| Line 213 \| public class Phaser {
213		private static final int phaseMask = 0x7fffffff;
214
215		private static int unarrivedOf(long s) {
216	<	return (int)(s & ushortMask);
216	>	return (int) (s & ushortMask);
217		}
218
219		private static int partiesOf(long s) {
220	<	return ((int)s) >>> 16;
220	>	return ((int) s) >>> 16;
221		}
222
223		private static int phaseOf(long s) {
224	<	return (int)(s >>> 32);
224	>	return (int) (s >>> 32);
225		}
226
227		private static int arrivedOf(long s) {
#	Line 228 \| Line 229 \| public class Phaser {
229		}
230
231		private static long stateFor(int phase, int parties, int unarrived) {
232	<	return ((((long)phase) << 32) \| (((long)parties) << 16) \|
233	<	(long)unarrived);
232	>	return ((((long) phase) << 32) \| (((long) parties) << 16) \|
233	>	(long) unarrived);
234		}
235
236		private static long trippedStateFor(int phase, int parties) {
237	<	long lp = (long)parties;
238	<	return (((long)phase) << 32) \| (lp << 16) \| lp;
237	>	long lp = (long) parties;
238	>	return (((long) phase) << 32) \| (lp << 16) \| lp;
239		}
240
241		/**
242	<	* Returns message string for bad bounds exceptions
242	>	* Returns message string for bad bounds exceptions.
243		*/
244		private static String badBounds(int parties, int unarrived) {
245		return ("Attempt to set " + unarrived +
#	Line 251 \| Line 252 \| public class Phaser {
252		private final Phaser parent;
253
254		/**
255	<	* The root of Phaser tree. Equals this if not in a tree. Used to
255	>	* The root of phaser tree. Equals this if not in a tree. Used to
256		* support faster state push-down.
257		*/
258		private final Phaser root;
#	Line 267 \| Line 268 \| public class Phaser {
268		private final AtomicReference<QNode> oddQ = new AtomicReference<QNode>();
269
270		private AtomicReference<QNode> queueFor(int phase) {
271	<	return (phase & 1) == 0? evenQ : oddQ;
271	>	return ((phase & 1) == 0) ? evenQ : oddQ;
272		}
273
274		/**
#	Line 275 \| Line 276 \| public class Phaser {
276		* root if necessary.
277		*/
278		private long getReconciledState() {
279	<	return parent == null? state : reconcileState();
279	>	return (parent == null) ? state : reconcileState();
280		}
281
282		/**
#	Line 302 \| Line 303 \| public class Phaser {
303		}
304
305		/**
306	<	* Creates a new Phaser without any initially registered parties,
306	>	* Creates a new phaser without any initially registered parties,
307		* initial phase number 0, and no parent. Any thread using this
308	<	* Phaser will need to first register for it.
308	>	* phaser will need to first register for it.
309		*/
310		public Phaser() {
311		this(null);
312		}
313
314		/**
315	<	* Creates a new Phaser with the given numbers of registered
315	>	* Creates a new phaser with the given numbers of registered
316		* unarrived parties, initial phase number 0, and no parent.
317	<	* @param parties the number of parties required to trip barrier.
317	>	*
318	>	* @param parties the number of parties required to trip barrier
319		* @throws IllegalArgumentException if parties less than zero
320	<	* or greater than the maximum number of parties supported.
320	>	* or greater than the maximum number of parties supported
321		*/
322		public Phaser(int parties) {
323		this(null, parties);
324		}
325
326		/**
327	<	* Creates a new Phaser with the given parent, without any
327	>	* Creates a new phaser with the given parent, without any
328		* initially registered parties. If parent is non-null this phaser
329		* is registered with the parent and its initial phase number is
330		* the same as that of parent phaser.
331	<	* @param parent the parent phaser.
331	>	*
332	>	* @param parent the parent phaser
333		*/
334		public Phaser(Phaser parent) {
335		int phase = 0;
#	Line 341 \| Line 344 \| public class Phaser {
344		}
345
346		/**
347	<	* Creates a new Phaser with the given parent and numbers of
348	<	* registered unarrived parties. If parent is non-null this phaser
347	>	* Creates a new phaser with the given parent and numbers of
348	>	* registered unarrived parties. If parent is non-null, this phaser
349		* is registered with the parent and its initial phase number is
350		* the same as that of parent phaser.
351	<	* @param parent the parent phaser.
352	<	* @param parties the number of parties required to trip barrier.
351	>	*
352	>	* @param parent the parent phaser
353	>	* @param parties the number of parties required to trip barrier
354		* @throws IllegalArgumentException if parties less than zero
355	<	* or greater than the maximum number of parties supported.
355	>	* or greater than the maximum number of parties supported
356		*/
357		public Phaser(Phaser parent, int parties) {
358		if (parties < 0 \|\| parties > ushortMask)
#	Line 366 \| Line 370 \| public class Phaser {
370
371		/**
372		* Adds a new unarrived party to this phaser.
373	<	* @return the current barrier phase number upon registration
373	>	*
374	>	* @return the arrival phase number to which this registration applied
375		* @throws IllegalStateException if attempting to register more
376	<	* than the maximum supported number of parties.
376	>	* than the maximum supported number of parties
377		*/
378		public int register() {
379		return doRegister(1);
#	Line 376 \| Line 381 \| public class Phaser {
381
382		/**
383		* Adds the given number of new unarrived parties to this phaser.
384	<	* @param parties the number of parties required to trip barrier.
385	<	* @return the current barrier phase number upon registration
384	>	*
385	>	* @param parties the number of parties required to trip barrier
386	>	* @return the arrival phase number to which this registration applied
387		* @throws IllegalStateException if attempting to register more
388	<	* than the maximum supported number of parties.
388	>	* than the maximum supported number of parties
389		*/
390		public int bulkRegister(int parties) {
391		if (parties < 0)
#	Line 414 \| Line 420 \| public class Phaser {
420		* Arrives at the barrier, but does not wait for others. (You can
421		* in turn wait for others via {@link #awaitAdvance}).
422		*
423	<	* @return the barrier phase number upon entry to this method, or a
418	<	* negative value if terminated;
423	>	* @return the arrival phase number, or a negative value if terminated
424		* @throws IllegalStateException if not terminated and the number
425	<	* of unarrived parties would become negative.
425	>	* of unarrived parties would become negative
426		*/
427		public int arrive() {
428		int phase;
#	Line 437 \| Line 442 \| public class Phaser {
442		if (par == null) { // directly trip
443		if (casState
444		(s,
445	<	trippedStateFor(onAdvance(phase, parties)? -1 :
445	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
446		((phase + 1) & phaseMask), parties))) {
447		releaseWaiters(phase);
448		break;
#	Line 460 \| Line 465 \| public class Phaser {
465		}
466
467		/**
468	<	* Arrives at the barrier, and deregisters from it, without
469	<	* waiting for others. Deregistration reduces number of parties
468	>	* Arrives at the barrier and deregisters from it without waiting
469	>	* for others. Deregistration reduces the number of parties
470		* required to trip the barrier in future phases. If this phaser
471		* has a parent, and deregistration causes this phaser to have
472	<	* zero parties, this phaser is also deregistered from its parent.
472	>	* zero parties, this phaser also arrives at and is deregistered
473	>	* from its parent.
474		*
475	<	* @return the current barrier phase number upon entry to
470	<	* this method, or a negative value if terminated;
475	>	* @return the arrival phase number, or a negative value if terminated
476		* @throws IllegalStateException if not terminated and the number
477	<	* of registered or unarrived parties would become negative.
477	>	* of registered or unarrived parties would become negative
478		*/
479		public int arriveAndDeregister() {
480		// similar code to arrive, but too different to merge
#	Line 498 \| Line 503 \| public class Phaser {
503		if (unarrived == 0) {
504		if (casState
505		(s,
506	<	trippedStateFor(onAdvance(phase, parties)? -1 :
506	>	trippedStateFor(onAdvance(phase, parties) ? -1 :
507		((phase + 1) & phaseMask), parties))) {
508		releaseWaiters(phase);
509		break;
#	Line 517 \| Line 522 \| public class Phaser {
522
523		/**
524		* Arrives at the barrier and awaits others. Equivalent in effect
525	<	* to {@code awaitAdvance(arrive())}. If you instead need to
526	<	* await with interruption of timeout, and/or deregister upon
527	<	* arrival, you can arrange them using analogous constructions.
528	<	* @return the phase on entry to this method
525	>	* to {@code awaitAdvance(arrive())}. If you need to await with
526	>	* interruption or timeout, you can arrange this with an analogous
527	>	* construction using one of the other forms of the awaitAdvance
528	>	* method. If instead you need to deregister upon arrival use
529	>	* {@code arriveAndDeregister}.
530	>	*
531	>	* @return the arrival phase number, or a negative number if terminated
532		* @throws IllegalStateException if not terminated and the number
533	<	* of unarrived parties would become negative.
533	>	* of unarrived parties would become negative
534		*/
535		public int arriveAndAwaitAdvance() {
536		return awaitAdvance(arrive());
537		}
538
539		/**
540	<	* Awaits the phase of the barrier to advance from the given
541	<	* value, or returns immediately if argument is negative or this
542	<	* barrier is terminated.
543	<	* @param phase the phase on entry to this method
544	<	* @return the phase on exit from this method
540	>	* Awaits the phase of the barrier to advance from the given phase
541	>	* value, returning immediately if the current phase of the
542	>	* barrier is not equal to the given phase value or this barrier
543	>	* is terminated.
544	>	*
545	>	* @param phase an arrival phase number, or negative value if
546	>	* terminated; this argument is normally the value returned by a
547	>	* previous call to {@code arrive} or its variants
548	>	* @return the next arrival phase number, or a negative value
549	>	* if terminated or argument is negative
550		*/
551		public int awaitAdvance(int phase) {
552		if (phase < 0)
#	Line 549 \| Line 562 \| public class Phaser {
562		}
563
564		/**
565	<	* Awaits the phase of the barrier to advance from the given
566	<	* value, or returns immediately if argument is negative or this
567	<	* barrier is terminated, or throws InterruptedException if
568	<	* interrupted while waiting.
569	<	* @param phase the phase on entry to this method
570	<	* @return the phase on exit from this method
565	>	* Awaits the phase of the barrier to advance from the given phase
566	>	* value, throwing {@code InterruptedException} if interrupted while
567	>	* waiting, or returning immediately if the current phase of the
568	>	* barrier is not equal to the given phase value or this barrier
569	>	* is terminated.
570	>	*
571	>	* @param phase an arrival phase number, or negative value if
572	>	* terminated; this argument is normally the value returned by a
573	>	* previous call to {@code arrive} or its variants
574	>	* @return the next arrival phase number, or a negative value
575	>	* if terminated or argument is negative
576		* @throws InterruptedException if thread interrupted while waiting
577		*/
578		public int awaitAdvanceInterruptibly(int phase)
#	Line 571 \| Line 589 \| public class Phaser {
589		}
590
591		/**
592	<	* Awaits the phase of the barrier to advance from the given value
593	<	* or the given timeout elapses, or returns immediately if
594	<	* argument is negative or this barrier is terminated.
595	<	* @param phase the phase on entry to this method
596	<	* @return the phase on exit from this method
592	>	* Awaits the phase of the barrier to advance from the given phase
593	>	* value or the given timeout to elapse, throwing
594	>	* {@code InterruptedException} if interrupted while waiting, or
595	>	* returning immediately if the current phase of the barrier is not
596	>	* equal to the given phase value or this barrier is terminated.
597	>	*
598	>	* @param phase an arrival phase number, or negative value if
599	>	* terminated; this argument is normally the value returned by a
600	>	* previous call to {@code arrive} or its variants
601	>	* @param timeout how long to wait before giving up, in units of
602	>	* {@code unit}
603	>	* @param unit a {@code TimeUnit} determining how to interpret the
604	>	* {@code timeout} parameter
605	>	* @return the next arrival phase number, or a negative value
606	>	* if terminated or argument is negative
607		* @throws InterruptedException if thread interrupted while waiting
608		* @throws TimeoutException if timed out while waiting
609		*/
610	<	public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit)
610	>	public int awaitAdvanceInterruptibly(int phase,
611	>	long timeout, TimeUnit unit)
612		throws InterruptedException, TimeoutException {
613		if (phase < 0)
614		return phase;
#	Line 620 \| Line 649 \| public class Phaser {
649		* Returns the current phase number. The maximum phase number is
650		* {@code Integer.MAX_VALUE}, after which it restarts at
651		* zero. Upon termination, the phase number is negative.
652	+	*
653		* @return the phase number, or a negative value if terminated
654		*/
655		public final int getPhase() {
#	Line 627 \| Line 657 \| public class Phaser {
657		}
658
659		/**
630	–	* Returns {@code true} if the current phase number equals the given phase.
631	–	* @param phase the 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;
636	–	}
637	–
638	–	/**
660		* Returns the number of parties registered at this barrier.
661	+	*
662		* @return the number of parties
663		*/
664		public int getRegisteredParties() {
#	Line 646 \| Line 668 \| public class Phaser {
668		/**
669		* Returns the number of parties that have arrived at the current
670		* phase of this barrier.
671	+	*
672		* @return the number of arrived parties
673		*/
674		public int getArrivedParties() {
#	Line 655 \| Line 678 \| public class Phaser {
678		/**
679		* Returns the number of registered parties that have not yet
680		* arrived at the current phase of this barrier.
681	+	*
682		* @return the number of unarrived parties
683		*/
684		public int getUnarrivedParties() {
#	Line 662 \| Line 686 \| public class Phaser {
686		}
687
688		/**
689	<	* Returns the parent of this phaser, or null if none.
690	<	* @return the parent of this phaser, or null if none
689	>	* Returns the parent of this phaser, or {@code null} if none.
690	>	*
691	>	* @return the parent of this phaser, or {@code null} if none
692		*/
693		public Phaser getParent() {
694		return parent;
#	Line 672 \| Line 697 \| public class Phaser {
697		/**
698		* Returns the root ancestor of this phaser, which is the same as
699		* this phaser if it has no parent.
700	+	*
701		* @return the root ancestor of this phaser
702		*/
703		public Phaser getRoot() {
#	Line 680 \| Line 706 \| public class Phaser {
706
707		/**
708		* Returns {@code true} if this barrier has been terminated.
709	+	*
710		* @return {@code true} if this barrier has been terminated
711		*/
712		public boolean isTerminated() {
#	Line 690 \| Line 717 \| public class Phaser {
717		* Overridable method to perform an action upon phase advance, and
718		* to control termination. This method is invoked whenever the
719		* barrier is tripped (and thus all other waiting parties are
720	<	* dormant). If it returns true, then, rather than advance the
721	<	* phase number, this barrier will be set to a final termination
722	<	* state, and subsequent calls to {@code isTerminated} will
723	<	* return true.
720	>	* dormant). If it returns {@code true}, then, rather than advance
721	>	* the phase number, this barrier will be set to a final
722	>	* termination state, and subsequent calls to {@link #isTerminated}
723	>	* will return true.
724		*
725	<	* <p> The default version returns true when the number of
725	>	* <p>The default version returns {@code true} when the number of
726		* registered parties is zero. Normally, overrides that arrange
727		* termination for other reasons should also preserve this
728		* property.
729		*
730	<	* <p> You may override this method to perform an action with side
730	>	* <p>You may override this method to perform an action with side
731		* effects visible to participating tasks, but it is in general
732		* only sensible to do so in designs where all parties register
733	<	* before any arrive, and all {@code awaitAdvance} at each phase.
734	<	* Otherwise, you cannot ensure lack of interference. In
735	<	* particular, this method may be invoked more than once per
709	<	* transition if other parties successfully register while the
710	<	* invocation of this method is in progress, thus postponing the
711	<	* transition until those parties also arrive, re-triggering this
712	<	* method.
733	>	* before any arrive, and all {@link #awaitAdvance} at each phase.
734	>	* Otherwise, you cannot ensure lack of interference from other
735	>	* parties during the invocation of this method.
736		*
737		* @param phase the phase number on entering the barrier
738		* @param registeredParties the current number of registered parties
#	Line 803 \| Line 826 \| public class Phaser {
826		}
827
828		/**
829	<	* Removes and signals waiting threads from wait queue
829	>	* Removes and signals waiting threads from wait queue.
830		*/
831		private void releaseWaiters(int phase) {
832		AtomicReference<QNode> head = queueFor(phase);
#	Line 815 \| Line 838 \| public class Phaser {
838		}
839
840		/**
841	<	* Tries to enqueue given node in the appropriate wait queue
841	>	* Tries to enqueue given node in the appropriate wait queue.
842	>	*
843		* @return true if successful
844		*/
845		private boolean tryEnqueue(QNode node) {
#	Line 825 \| Line 849 \| public class Phaser {
849
850		/**
851		* Enqueues node and waits unless aborted or signalled.
852	+	*
853		* @return current phase
854		*/
855		private int untimedWait(int phase) {
#	Line 912 \| Line 937 \| public class Phaser {
937		return p;
938		}
939
940	<	// 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	<	}
940	>	// Unsafe mechanics
941
942	<	private static Unsafe getUnsafePrivileged()
943	<	throws NoSuchFieldException, IllegalAccessException {
944	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
935	<	f.setAccessible(true);
936	<	return (Unsafe) f.get(null);
937	<	}
942	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
943	>	private static final long stateOffset =
944	>	objectFieldOffset("state", Phaser.class);
945
946	<	private static long fieldOffset(String fieldName)
947	<	throws NoSuchFieldException {
941	<	return _unsafe.objectFieldOffset
942	<	(Phaser.class.getDeclaredField(fieldName));
946	>	private final boolean casState(long cmp, long val) {
947	>	return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val);
948		}
949
950	<	static final Unsafe _unsafe;
946	<	static final long stateOffset;
947	<
948	<	static {
950	>	private static long objectFieldOffset(String field, Class<?> klazz) {
951		try {
952	<	_unsafe = getUnsafe();
953	<	stateOffset = fieldOffset("state");
954	<	} catch (Throwable e) {
955	<	throw new RuntimeException("Could not initialize intrinsics", e);
952	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
953	>	} catch (NoSuchFieldException e) {
954	>	// Convert Exception to corresponding Error
955	>	NoSuchFieldError error = new NoSuchFieldError(field);
956	>	error.initCause(e);
957	>	throw error;
958		}
959		}
960
961	<	final boolean casState(long cmp, long val) {
962	<	return _unsafe.compareAndSwapLong(this, stateOffset, cmp, val);
961	>	/**
962	>	* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package.
963	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
964	>	* into a jdk.
965	>	*
966	>	* @return a sun.misc.Unsafe
967	>	*/
968	>	private static sun.misc.Unsafe getUnsafe() {
969	>	try {
970	>	return sun.misc.Unsafe.getUnsafe();
971	>	} catch (SecurityException se) {
972	>	try {
973	>	return java.security.AccessController.doPrivileged
974	>	(new java.security
975	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
976	>	public sun.misc.Unsafe run() throws Exception {
977	>	java.lang.reflect.Field f = sun.misc
978	>	.Unsafe.class.getDeclaredField("theUnsafe");
979	>	f.setAccessible(true);
980	>	return (sun.misc.Unsafe) f.get(null);
981	>	}});
982	>	} catch (java.security.PrivilegedActionException e) {
983	>	throw new RuntimeException("Could not initialize intrinsics",
984	>	e.getCause());
985	>	}
986	>	}
987		}
988		}

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Comparing jsr166/src/jsr166y/Phaser.java (file contents): Revision 1.12 by jsr166, Thu Mar 19 05:10:42 2009 UTC vs. Revision 1.35 by dl, Sun Aug 23 13:37:08 2009 UTC

Diff Legend

Comparing jsr166/src/jsr166y/Phaser.java (file contents):
Revision 1.12 by jsr166, Thu Mar 19 05:10:42 2009 UTC vs.
Revision 1.35 by dl, Sun Aug 23 13:37:08 2009 UTC