| 30 |
|
* zero, and advancing when all parties reach the barrier (wrapping |
| 31 |
|
* around to zero after reaching {@code Integer.MAX_VALUE}). |
| 32 |
|
* |
| 33 |
< |
* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited. |
| 34 |
< |
* Method {@code arriveAndAwaitAdvance} has effect analogous to |
| 35 |
< |
* {@code CyclicBarrier.await}. However, Phasers separate two |
| 36 |
< |
* aspects of coordination, that may also be invoked independently: |
| 33 |
> |
* <li> Like a {@code CyclicBarrier}, a Phaser may be repeatedly |
| 34 |
> |
* awaited. Method {@link #arriveAndAwaitAdvance} has effect |
| 35 |
> |
* analogous to {@link java.util.concurrent.CyclicBarrier#await |
| 36 |
> |
* CyclicBarrier.await}. However, phasers separate two aspects of |
| 37 |
> |
* coordination, that may also be invoked independently: |
| 38 |
|
* |
| 39 |
|
* <ul> |
| 40 |
|
* |
| 41 |
< |
* <li> Arriving at a barrier. Methods {@code arrive} and |
| 42 |
< |
* {@code arriveAndDeregister} do not block, but return |
| 41 |
> |
* <li> Arriving at a barrier. Methods {@link #arrive} and |
| 42 |
> |
* {@link #arriveAndDeregister} do not block, but return |
| 43 |
|
* the phase value current upon entry to the method. |
| 44 |
|
* |
| 45 |
< |
* <li> Awaiting others. Method {@code awaitAdvance} requires an |
| 45 |
> |
* <li> Awaiting others. Method {@link #awaitAdvance} requires an |
| 46 |
|
* argument indicating the entry phase, and returns when the |
| 47 |
|
* barrier advances to a new phase. |
| 48 |
|
* </ul> |
| 50 |
|
* |
| 51 |
|
* <li> Barrier actions, performed by the task triggering a phase |
| 52 |
|
* advance while others may be waiting, are arranged by overriding |
| 53 |
< |
* method {@code onAdvance}, that also controls termination. |
| 53 |
> |
* method {@link #onAdvance}, that also controls termination. |
| 54 |
|
* Overriding this method may be used to similar but more flexible |
| 55 |
< |
* effect as providing a barrier action to a CyclicBarrier. |
| 55 |
> |
* effect as providing a barrier action to a {@code CyclicBarrier}. |
| 56 |
|
* |
| 57 |
|
* <li> Phasers may enter a <em>termination</em> state in which all |
| 58 |
|
* actions immediately return without updating phaser state or waiting |
| 59 |
|
* for advance, and indicating (via a negative phase value) that |
| 60 |
|
* execution is complete. Termination is triggered by executing the |
| 61 |
|
* overridable {@code onAdvance} method that is invoked each time the |
| 62 |
< |
* barrier is about to be tripped. When a Phaser is controlling an |
| 62 |
> |
* barrier is about to be tripped. When a phaser is controlling an |
| 63 |
|
* action with a fixed number of iterations, it is often convenient to |
| 64 |
|
* override this method to cause termination when the current phase |
| 65 |
< |
* number reaches a threshold. Method {@code forceTermination} is also |
| 65 |
> |
* number reaches a threshold. Method {@link #forceTermination} is also |
| 66 |
|
* available to abruptly release waiting threads and allow them to |
| 67 |
|
* terminate. |
| 68 |
|
* |
| 74 |
|
* |
| 75 |
|
* <li> By default, {@code awaitAdvance} continues to wait even if |
| 76 |
|
* the waiting thread is interrupted. And unlike the case in |
| 77 |
< |
* CyclicBarriers, exceptions encountered while tasks wait |
| 77 |
> |
* {@code CyclicBarrier}, exceptions encountered while tasks wait |
| 78 |
|
* interruptibly or with timeout do not change the state of the |
| 79 |
|
* barrier. If necessary, you can perform any associated recovery |
| 80 |
|
* within handlers of those exceptions, often after invoking |
| 86 |
|
* |
| 87 |
|
* <p><b>Sample usages:</b> |
| 88 |
|
* |
| 89 |
< |
* <p>A Phaser may be used instead of a {@code CountDownLatch} to control |
| 90 |
< |
* a one-shot action serving a variable number of parties. The typical |
| 91 |
< |
* idiom is for the method setting this up to first register, then |
| 92 |
< |
* start the actions, then deregister, as in: |
| 89 |
> |
* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch} |
| 90 |
> |
* to control a one-shot action serving a variable number of |
| 91 |
> |
* parties. The typical idiom is for the method setting this up to |
| 92 |
> |
* first register, then start the actions, then deregister, as in: |
| 93 |
|
* |
| 94 |
|
* <pre> {@code |
| 95 |
|
* void runTasks(List<Runnable> list) { |
| 138 |
|
* phaser.arriveAndDeregister(); // deregister self, don't wait |
| 139 |
|
* }}</pre> |
| 140 |
|
* |
| 141 |
< |
* <p> To create a set of tasks using a tree of Phasers, |
| 141 |
> |
* <p> To create a set of tasks using a tree of phasers, |
| 142 |
|
* you could use code of the following form, assuming a |
| 143 |
< |
* Task class with a constructor accepting a Phaser that |
| 143 |
> |
* Task class with a constructor accepting a phaser that |
| 144 |
|
* it registers for upon construction: |
| 145 |
|
* <pre> {@code |
| 146 |
|
* void build(Task[] actions, int lo, int hi, Phaser b) { |
| 248 |
|
private final Phaser parent; |
| 249 |
|
|
| 250 |
|
/** |
| 251 |
< |
* The root of Phaser tree. Equals this if not in a tree. Used to |
| 251 |
> |
* The root of phaser tree. Equals this if not in a tree. Used to |
| 252 |
|
* support faster state push-down. |
| 253 |
|
*/ |
| 254 |
|
private final Phaser root; |
| 299 |
|
} |
| 300 |
|
|
| 301 |
|
/** |
| 302 |
< |
* Creates a new Phaser without any initially registered parties, |
| 302 |
> |
* Creates a new phaser without any initially registered parties, |
| 303 |
|
* initial phase number 0, and no parent. Any thread using this |
| 304 |
< |
* Phaser will need to first register for it. |
| 304 |
> |
* phaser will need to first register for it. |
| 305 |
|
*/ |
| 306 |
|
public Phaser() { |
| 307 |
|
this(null); |
| 308 |
|
} |
| 309 |
|
|
| 310 |
|
/** |
| 311 |
< |
* Creates a new Phaser with the given numbers of registered |
| 311 |
> |
* Creates a new phaser with the given numbers of registered |
| 312 |
|
* unarrived parties, initial phase number 0, and no parent. |
| 313 |
|
* |
| 314 |
|
* @param parties the number of parties required to trip barrier |
| 320 |
|
} |
| 321 |
|
|
| 322 |
|
/** |
| 323 |
< |
* Creates a new Phaser with the given parent, without any |
| 323 |
> |
* Creates a new phaser with the given parent, without any |
| 324 |
|
* initially registered parties. If parent is non-null this phaser |
| 325 |
|
* is registered with the parent and its initial phase number is |
| 326 |
|
* the same as that of parent phaser. |
| 340 |
|
} |
| 341 |
|
|
| 342 |
|
/** |
| 343 |
< |
* Creates a new Phaser with the given parent and numbers of |
| 343 |
> |
* Creates a new phaser with the given parent and numbers of |
| 344 |
|
* registered unarrived parties. If parent is non-null, this phaser |
| 345 |
|
* is registered with the parent and its initial phase number is |
| 346 |
|
* the same as that of parent phaser. |
| 674 |
|
} |
| 675 |
|
|
| 676 |
|
/** |
| 677 |
< |
* Returns the parent of this phaser, or null if none. |
| 677 |
> |
* Returns the parent of this phaser, or {@code null} if none. |
| 678 |
|
* |
| 679 |
< |
* @return the parent of this phaser, or null if none |
| 679 |
> |
* @return the parent of this phaser, or {@code null} if none |
| 680 |
|
*/ |
| 681 |
|
public Phaser getParent() { |
| 682 |
|
return parent; |
| 705 |
|
* Overridable method to perform an action upon phase advance, and |
| 706 |
|
* to control termination. This method is invoked whenever the |
| 707 |
|
* barrier is tripped (and thus all other waiting parties are |
| 708 |
< |
* dormant). If it returns true, then, rather than advance the |
| 709 |
< |
* phase number, this barrier will be set to a final termination |
| 710 |
< |
* state, and subsequent calls to {@code isTerminated} will |
| 711 |
< |
* return true. |
| 708 |
> |
* dormant). If it returns {@code true}, then, rather than advance |
| 709 |
> |
* the phase number, this barrier will be set to a final |
| 710 |
> |
* termination state, and subsequent calls to {@link #isTerminated} |
| 711 |
> |
* will return true. |
| 712 |
|
* |
| 713 |
< |
* <p> The default version returns true when the number of |
| 713 |
> |
* <p> The default version returns {@code true} when the number of |
| 714 |
|
* registered parties is zero. Normally, overrides that arrange |
| 715 |
|
* termination for other reasons should also preserve this |
| 716 |
|
* property. |
| 718 |
|
* <p> You may override this method to perform an action with side |
| 719 |
|
* effects visible to participating tasks, but it is in general |
| 720 |
|
* only sensible to do so in designs where all parties register |
| 721 |
< |
* before any arrive, and all {@code awaitAdvance} at each phase. |
| 721 |
> |
* before any arrive, and all {@link #awaitAdvance} at each phase. |
| 722 |
|
* Otherwise, you cannot ensure lack of interference. In |
| 723 |
|
* particular, this method may be invoked more than once per |
| 724 |
|
* transition if other parties successfully register while the |
