19 |
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* |
20 |
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* <ul> |
21 |
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* |
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 |
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* subclassing this class.) |
33 |
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* |
34 |
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* <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 {@code CyclicBarrier}, a phaser may be repeatedly |
39 |
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* awaited. Method {@link #arriveAndAwaitAdvance} has effect |
45 |
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* |
46 |
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* <li> Arriving at a barrier. Methods {@link #arrive} and |
47 |
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* {@link #arriveAndDeregister} do not block, but return |
48 |
< |
* the phase value current upon entry to the method. |
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 the entry phase, and returns when the |
54 |
< |
* barrier advances to a new phase. |
53 |
> |
* argument indicating an arrival phase number, and returns |
54 |
> |
* when the barrier advances to a new phase. |
55 |
|
* </ul> |
56 |
|
* |
57 |
|
* |
100 |
|
* first register, then start the actions, then deregister, as in: |
101 |
|
* |
102 |
|
* <pre> {@code |
103 |
< |
* void runTasks(List<Runnable> list) { |
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 r : list) { |
106 |
> |
* for (Runnable task : tasks) { |
107 |
|
* phaser.register(); |
108 |
|
* new Thread() { |
109 |
|
* public void run() { |
110 |
|
* phaser.arriveAndAwaitAdvance(); // await all creation |
111 |
< |
* r.run(); |
111 |
> |
* task.run(); |
112 |
|
* } |
113 |
|
* }.start(); |
114 |
|
* } |
121 |
|
* for a given number of iterations is to override {@code onAdvance}: |
122 |
|
* |
123 |
|
* <pre> {@code |
124 |
< |
* void startTasks(List<Runnable> list, final int iterations) { |
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 r : list) { |
131 |
> |
* for (Runnable task : tasks) { |
132 |
|
* phaser.register(); |
133 |
|
* new Thread() { |
134 |
|
* public void run() { |
135 |
|
* do { |
136 |
< |
* r.run(); |
136 |
> |
* task.run(); |
137 |
|
* phaser.arriveAndAwaitAdvance(); |
138 |
|
* } while(!phaser.isTerminated(); |
139 |
|
* } |
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 |
|
* |
371 |
|
/** |
372 |
|
* Adds a new unarrived party to this phaser. |
373 |
|
* |
374 |
< |
* @return the current barrier phase number upon registration |
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 |
377 |
|
*/ |
383 |
|
* Adds the given number of new unarrived parties to this phaser. |
384 |
|
* |
385 |
|
* @param parties the number of parties required to trip barrier |
386 |
< |
* @return the current barrier phase number upon registration |
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 |
389 |
|
*/ |
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 |
419 |
< |
* 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 |
426 |
|
*/ |
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 |
472 |
< |
* 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 |
478 |
|
*/ |
528 |
|
* method. If instead you need to deregister upon arrival use |
529 |
|
* {@code arriveAndDeregister}. |
530 |
|
* |
531 |
< |
* @return the phase on entry to this method |
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 |
534 |
|
*/ |
542 |
|
* barrier is not equal to the given phase value or this barrier |
543 |
|
* is terminated. |
544 |
|
* |
545 |
< |
* @param phase the phase on entry to this method |
546 |
< |
* @return the phase on exit from this method |
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) |
563 |
|
|
564 |
|
/** |
565 |
|
* Awaits the phase of the barrier to advance from the given phase |
566 |
< |
* value, throwing InterruptedException if interrupted while |
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 |
569 |
> |
* is terminated. |
570 |
|
* |
571 |
< |
* @param phase the phase on entry to this method |
572 |
< |
* @return the phase on exit from this method |
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) |
590 |
|
|
591 |
|
/** |
592 |
|
* Awaits the phase of the barrier to advance from the given phase |
593 |
< |
* value or the given timeout elapses, throwing |
594 |
< |
* InterruptedException if interrupted while waiting, or returning |
595 |
< |
* immediately if the current phase of the barrier is not equal to |
596 |
< |
* the given phase value or this barrier is terminated. |
597 |
< |
* |
598 |
< |
* @param phase the phase on entry to this method |
599 |
< |
* @return the phase on exit from this method |
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 |
|
*/ |