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 |
15 |
> |
* A reusable synchronization barrier, similar in functionality to |
16 |
|
* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and |
17 |
|
* {@link java.util.concurrent.CountDownLatch CountDownLatch} |
18 |
|
* but supporting more flexible usage. |
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 |
28 |
< |
* registered. (However, you can introduce such bookkeeping by |
29 |
< |
* subclassing this class.) |
30 |
< |
* |
31 |
< |
* <li> Each generation has an associated phase value, starting at |
32 |
< |
* zero, and advancing when all parties reach the barrier (wrapping |
33 |
< |
* around to zero after reaching {@code Integer.MAX_VALUE}). |
34 |
< |
* |
35 |
< |
* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited. |
36 |
< |
* Method {@code arriveAndAwaitAdvance} has effect analogous to |
37 |
< |
* {@code CyclicBarrier.await}. However, Phasers separate two |
38 |
< |
* aspects of coordination, that may also be invoked independently: |
20 |
> |
* <p> <b>Registration.</b> Unlike the case for other barriers, the |
21 |
> |
* number of parties <em>registered</em> to synchronize on a phaser |
22 |
> |
* may vary over time. Tasks may be registered at any time (using |
23 |
> |
* methods {@link #register}, {@link #bulkRegister}, or forms of |
24 |
> |
* constructors establishing initial numbers of parties), and |
25 |
> |
* optionally deregistered upon any arrival (using {@link |
26 |
> |
* #arriveAndDeregister}). As is the case with most basic |
27 |
> |
* synchronization constructs, registration and deregistration affect |
28 |
> |
* only internal counts; they do not establish any further internal |
29 |
> |
* bookkeeping, so tasks cannot query whether they are registered. |
30 |
> |
* (However, you can introduce such bookkeeping by subclassing this |
31 |
> |
* class.) |
32 |
> |
* |
33 |
> |
* <p> <b>Synchronization.</b> Like a {@code CyclicBarrier}, a {@code |
34 |
> |
* Phaser} may be repeatedly awaited. Method {@link |
35 |
> |
* #arriveAndAwaitAdvance} has effect analogous to {@link |
36 |
> |
* java.util.concurrent.CyclicBarrier#await CyclicBarrier.await}. Each |
37 |
> |
* generation of a {@code Phaser} has an associated phase number. The |
38 |
> |
* phase number starts at zero, and advances when all parties arrive |
39 |
> |
* at the barrier, wrapping around to zero after reaching {@code |
40 |
> |
* Integer.MAX_VALUE}. The use of phase numbers enables independent |
41 |
> |
* control of actions upon arrival at a barrier and upon awaiting |
42 |
> |
* others, via two kinds of methods that may be invoked by any |
43 |
> |
* registered party: |
44 |
|
* |
45 |
|
* <ul> |
46 |
|
* |
47 |
< |
* <li> Arriving at a barrier. Methods {@code arrive} and |
48 |
< |
* {@code arriveAndDeregister} do not block, but return |
49 |
< |
* the phase value current upon entry to the method. |
50 |
< |
* |
51 |
< |
* <li> Awaiting others. Method {@code awaitAdvance} requires an |
52 |
< |
* argument indicating the entry phase, and returns when the |
53 |
< |
* barrier advances to a new phase. |
54 |
< |
* </ul> |
47 |
> |
* <li> <b>Arrival.</b> Methods {@link #arrive} and |
48 |
> |
* {@link #arriveAndDeregister} record arrival at a |
49 |
> |
* barrier. These methods do not block, but return an associated |
50 |
> |
* <em>arrival phase number</em>; that is, the phase number of |
51 |
> |
* the barrier to which the arrival applied. When the final |
52 |
> |
* party for a given phase arrives, an optional barrier action |
53 |
> |
* is performed and the phase advances. Barrier actions, |
54 |
> |
* performed by the party triggering a phase advance, are |
55 |
> |
* arranged by overriding method {@link #onAdvance(int, int)}, |
56 |
> |
* which also controls termination. Overriding this method is |
57 |
> |
* similar to, but more flexible than, providing a barrier |
58 |
> |
* action to a {@code CyclicBarrier}. |
59 |
> |
* |
60 |
> |
* <li> <b>Waiting.</b> Method {@link #awaitAdvance} requires an |
61 |
> |
* argument indicating an arrival phase number, and returns when |
62 |
> |
* the barrier advances to (or is already at) a different phase. |
63 |
> |
* Unlike similar constructions using {@code CyclicBarrier}, |
64 |
> |
* method {@code awaitAdvance} continues to wait even if the |
65 |
> |
* waiting thread is interrupted. Interruptible and timeout |
66 |
> |
* versions are also available, but exceptions encountered while |
67 |
> |
* tasks wait interruptibly or with timeout do not change the |
68 |
> |
* state of the barrier. If necessary, you can perform any |
69 |
> |
* associated recovery within handlers of those exceptions, |
70 |
> |
* often after invoking {@code forceTermination}. Phasers may |
71 |
> |
* also be used by tasks executing in a {@link ForkJoinPool}, |
72 |
> |
* which will ensure sufficient parallelism to execute tasks |
73 |
> |
* when others are blocked waiting for a phase to advance. |
74 |
|
* |
75 |
+ |
* </ul> |
76 |
|
* |
77 |
< |
* <li> Barrier actions, performed by the task triggering a phase |
78 |
< |
* advance while others may be waiting, are arranged by overriding |
79 |
< |
* method {@code onAdvance}, that also controls termination. |
80 |
< |
* Overriding this method may be used to similar but more flexible |
81 |
< |
* effect as providing a barrier action to a CyclicBarrier. |
82 |
< |
* |
83 |
< |
* <li> Phasers may enter a <em>termination</em> state in which all |
84 |
< |
* actions immediately return without updating phaser state or waiting |
85 |
< |
* for advance, and indicating (via a negative phase value) that |
86 |
< |
* execution is complete. Termination is triggered by executing the |
87 |
< |
* 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. |
77 |
> |
* <p> <b>Termination.</b> A {@code Phaser} may enter a |
78 |
> |
* <em>termination</em> state in which all synchronization methods |
79 |
> |
* immediately return without updating phaser state or waiting for |
80 |
> |
* advance, and indicating (via a negative phase value) that execution |
81 |
> |
* is complete. Termination is triggered when an invocation of {@code |
82 |
> |
* onAdvance} returns {@code true}. As illustrated below, when |
83 |
> |
* phasers control actions with a fixed number of iterations, it is |
84 |
> |
* often convenient to override this method to cause termination when |
85 |
> |
* the current phase number reaches a threshold. Method {@link |
86 |
> |
* #forceTermination} is also available to abruptly release waiting |
87 |
> |
* threads and allow them to terminate. |
88 |
|
* |
89 |
< |
* <li> Phasers may be tiered to reduce contention. Phasers with large |
89 |
> |
* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., arranged |
90 |
> |
* in tree structures) to reduce contention. Phasers with large |
91 |
|
* numbers of parties that would otherwise experience heavy |
92 |
< |
* synchronization contention costs may instead be arranged in trees. |
93 |
< |
* This will typically greatly increase throughput even though it |
94 |
< |
* incurs somewhat greater per-operation overhead. |
95 |
< |
* |
96 |
< |
* <li> By default, {@code awaitAdvance} continues to wait even if |
97 |
< |
* the waiting thread is interrupted. And unlike the case in |
98 |
< |
* CyclicBarriers, exceptions encountered while tasks wait |
99 |
< |
* interruptibly or with timeout do not change the state of the |
100 |
< |
* barrier. If necessary, you can perform any associated recovery |
101 |
< |
* within handlers of those exceptions, often after invoking |
102 |
< |
* {@code forceTermination}. |
103 |
< |
* |
104 |
< |
* <li>Phasers ensure lack of starvation when used by ForkJoinTasks. |
86 |
< |
* |
87 |
< |
* </ul> |
92 |
> |
* synchronization contention costs may instead be set up so that |
93 |
> |
* groups of sub-phasers share a common parent. This may greatly |
94 |
> |
* increase throughput even though it incurs greater per-operation |
95 |
> |
* overhead. |
96 |
> |
* |
97 |
> |
* <p><b>Monitoring.</b> While synchronization methods may be invoked |
98 |
> |
* only by registered parties, the current state of a phaser may be |
99 |
> |
* monitored by any caller. At any given moment there are {@link |
100 |
> |
* #getRegisteredParties}, where {@link #getArrivedParties} have |
101 |
> |
* arrived at the current phase ({@link #getPhase}). When the |
102 |
> |
* remaining {@link #getUnarrivedParties}) arrive, the phase |
103 |
> |
* advances. Method {@link #toString} returns snapshots of these state |
104 |
> |
* queries in a form convenient for informal monitoring. |
105 |
|
* |
106 |
|
* <p><b>Sample usages:</b> |
107 |
|
* |
108 |
< |
* <p>A Phaser may be used instead of a {@code CountDownLatch} to control |
109 |
< |
* a one-shot action serving a variable number of parties. The typical |
110 |
< |
* idiom is for the method setting this up to first register, then |
111 |
< |
* start the actions, then deregister, as in: |
108 |
> |
* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch} |
109 |
> |
* to control a one-shot action serving a variable number of |
110 |
> |
* parties. The typical idiom is for the method setting this up to |
111 |
> |
* first register, then start the actions, then deregister, as in: |
112 |
|
* |
113 |
|
* <pre> {@code |
114 |
< |
* void runTasks(List<Runnable> list) { |
114 |
> |
* void runTasks(List<Runnable> tasks) { |
115 |
|
* final Phaser phaser = new Phaser(1); // "1" to register self |
116 |
< |
* for (Runnable r : list) { |
116 |
> |
* // create and start threads |
117 |
> |
* for (Runnable task : tasks) { |
118 |
|
* phaser.register(); |
119 |
|
* new Thread() { |
120 |
|
* public void run() { |
121 |
|
* phaser.arriveAndAwaitAdvance(); // await all creation |
122 |
< |
* r.run(); |
105 |
< |
* phaser.arriveAndDeregister(); // signal completion |
122 |
> |
* task.run(); |
123 |
|
* } |
124 |
|
* }.start(); |
125 |
|
* } |
126 |
|
* |
127 |
< |
* doSomethingOnBehalfOfWorkers(); |
128 |
< |
* phaser.arrive(); // allow threads to start |
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); // await final completion |
127 |
> |
* // allow threads to start and deregister self |
128 |
> |
* phaser.arriveAndDeregister(); |
129 |
|
* }}</pre> |
130 |
|
* |
131 |
|
* <p>One way to cause a set of threads to repeatedly perform actions |
132 |
|
* for a given number of iterations is to override {@code onAdvance}: |
133 |
|
* |
134 |
|
* <pre> {@code |
135 |
< |
* void startTasks(List<Runnable> list, final int iterations) { |
135 |
> |
* void startTasks(List<Runnable> tasks, final int iterations) { |
136 |
|
* final Phaser phaser = new Phaser() { |
137 |
< |
* public boolean onAdvance(int phase, int registeredParties) { |
137 |
> |
* protected boolean onAdvance(int phase, int registeredParties) { |
138 |
|
* return phase >= iterations || registeredParties == 0; |
139 |
|
* } |
140 |
|
* }; |
141 |
|
* phaser.register(); |
142 |
< |
* for (Runnable r : list) { |
142 |
> |
* for (Runnable task : tasks) { |
143 |
|
* phaser.register(); |
144 |
|
* new Thread() { |
145 |
|
* public void run() { |
146 |
|
* do { |
147 |
< |
* r.run(); |
147 |
> |
* task.run(); |
148 |
|
* phaser.arriveAndAwaitAdvance(); |
149 |
|
* } while(!phaser.isTerminated(); |
150 |
|
* } |
153 |
|
* phaser.arriveAndDeregister(); // deregister self, don't wait |
154 |
|
* }}</pre> |
155 |
|
* |
156 |
< |
* <p> To create a set of tasks using a tree of Phasers, |
156 |
> |
* If the main task must later await termination, it |
157 |
> |
* may re-register and then execute a similar loop: |
158 |
> |
* <pre> {@code |
159 |
> |
* // ... |
160 |
> |
* phaser.register(); |
161 |
> |
* while (!phaser.isTerminated()) |
162 |
> |
* phaser.arriveAndAwaitAdvance(); |
163 |
> |
* }</pre> |
164 |
> |
* |
165 |
> |
* Related constructions may be used to await particular phase numbers |
166 |
> |
* in contexts where you are sure that the phase will never wrap around |
167 |
> |
* {@code Integer.MAX_VALUE}. For example: |
168 |
> |
* |
169 |
> |
* <pre> {@code |
170 |
> |
* void awaitPhase(Phaser phaser, int phase) { |
171 |
> |
* int p = phaser.register(); // assumes caller not already registered |
172 |
> |
* while (p < phase) { |
173 |
> |
* if (phaser.isTerminated()) |
174 |
> |
* // ... deal with unexpected termination |
175 |
> |
* else |
176 |
> |
* p = phaser.arriveAndAwaitAdvance(); |
177 |
> |
* } |
178 |
> |
* phaser.arriveAndDeregister(); |
179 |
> |
* } |
180 |
> |
* }</pre> |
181 |
> |
* |
182 |
> |
* |
183 |
> |
* <p>To create a set of tasks using a tree of phasers, |
184 |
|
* you could use code of the following form, assuming a |
185 |
< |
* Task class with a constructor accepting a Phaser that |
185 |
> |
* Task class with a constructor accepting a phaser that |
186 |
|
* it registers for upon construction: |
187 |
|
* <pre> {@code |
188 |
|
* void build(Task[] actions, int lo, int hi, Phaser b) { |
212 |
|
* |
213 |
|
* <p><b>Implementation notes</b>: This implementation restricts the |
214 |
|
* maximum number of parties to 65535. Attempts to register additional |
215 |
< |
* parties result in IllegalStateExceptions. However, you can and |
215 |
> |
* parties result in {@code IllegalStateException}. However, you can and |
216 |
|
* should create tiered phasers to accommodate arbitrarily large sets |
217 |
|
* of participants. |
218 |
|
* |
251 |
|
private static final int phaseMask = 0x7fffffff; |
252 |
|
|
253 |
|
private static int unarrivedOf(long s) { |
254 |
< |
return (int)(s & ushortMask); |
254 |
> |
return (int) (s & ushortMask); |
255 |
|
} |
256 |
|
|
257 |
|
private static int partiesOf(long s) { |
290 |
|
private final Phaser parent; |
291 |
|
|
292 |
|
/** |
293 |
< |
* The root of Phaser tree. Equals this if not in a tree. Used to |
293 |
> |
* The root of phaser tree. Equals this if not in a tree. Used to |
294 |
|
* support faster state push-down. |
295 |
|
*/ |
296 |
|
private final Phaser root; |
306 |
|
private final AtomicReference<QNode> oddQ = new AtomicReference<QNode>(); |
307 |
|
|
308 |
|
private AtomicReference<QNode> queueFor(int phase) { |
309 |
< |
return (phase & 1) == 0? evenQ : oddQ; |
309 |
> |
return ((phase & 1) == 0) ? evenQ : oddQ; |
310 |
|
} |
311 |
|
|
312 |
|
/** |
314 |
|
* root if necessary. |
315 |
|
*/ |
316 |
|
private long getReconciledState() { |
317 |
< |
return parent == null? state : reconcileState(); |
317 |
> |
return (parent == null) ? state : reconcileState(); |
318 |
|
} |
319 |
|
|
320 |
|
/** |
341 |
|
} |
342 |
|
|
343 |
|
/** |
344 |
< |
* Creates a new Phaser without any initially registered parties, |
344 |
> |
* Creates a new phaser without any initially registered parties, |
345 |
|
* initial phase number 0, and no parent. Any thread using this |
346 |
< |
* Phaser will need to first register for it. |
346 |
> |
* phaser will need to first register for it. |
347 |
|
*/ |
348 |
|
public Phaser() { |
349 |
|
this(null); |
350 |
|
} |
351 |
|
|
352 |
|
/** |
353 |
< |
* Creates a new Phaser with the given numbers of registered |
353 |
> |
* Creates a new phaser with the given numbers of registered |
354 |
|
* unarrived parties, initial phase number 0, and no parent. |
355 |
|
* |
356 |
|
* @param parties the number of parties required to trip barrier |
362 |
|
} |
363 |
|
|
364 |
|
/** |
365 |
< |
* Creates a new Phaser with the given parent, without any |
365 |
> |
* Creates a new phaser with the given parent, without any |
366 |
|
* initially registered parties. If parent is non-null this phaser |
367 |
|
* is registered with the parent and its initial phase number is |
368 |
|
* the same as that of parent phaser. |
382 |
|
} |
383 |
|
|
384 |
|
/** |
385 |
< |
* Creates a new Phaser with the given parent and numbers of |
385 |
> |
* Creates a new phaser with the given parent and numbers of |
386 |
|
* registered unarrived parties. If parent is non-null, this phaser |
387 |
|
* is registered with the parent and its initial phase number is |
388 |
|
* the same as that of parent phaser. |
409 |
|
/** |
410 |
|
* Adds a new unarrived party to this phaser. |
411 |
|
* |
412 |
< |
* @return the current barrier phase number upon registration |
412 |
> |
* @return the arrival phase number to which this registration applied |
413 |
|
* @throws IllegalStateException if attempting to register more |
414 |
|
* than the maximum supported number of parties |
415 |
|
*/ |
421 |
|
* Adds the given number of new unarrived parties to this phaser. |
422 |
|
* |
423 |
|
* @param parties the number of parties required to trip barrier |
424 |
< |
* @return the current barrier phase number upon registration |
424 |
> |
* @return the arrival phase number to which this registration applied |
425 |
|
* @throws IllegalStateException if attempting to register more |
426 |
|
* than the maximum supported number of parties |
427 |
|
*/ |
456 |
|
|
457 |
|
/** |
458 |
|
* Arrives at the barrier, but does not wait for others. (You can |
459 |
< |
* in turn wait for others via {@link #awaitAdvance}). |
459 |
> |
* in turn wait for others via {@link #awaitAdvance}). It is an |
460 |
> |
* unenforced usage error for an unregistered party to invoke this |
461 |
> |
* method. |
462 |
|
* |
463 |
< |
* @return the barrier phase number upon entry to this method, or a |
422 |
< |
* negative value if terminated |
463 |
> |
* @return the arrival phase number, or a negative value if terminated |
464 |
|
* @throws IllegalStateException if not terminated and the number |
465 |
|
* of unarrived parties would become negative |
466 |
|
*/ |
482 |
|
if (par == null) { // directly trip |
483 |
|
if (casState |
484 |
|
(s, |
485 |
< |
trippedStateFor(onAdvance(phase, parties)? -1 : |
485 |
> |
trippedStateFor(onAdvance(phase, parties) ? -1 : |
486 |
|
((phase + 1) & phaseMask), parties))) { |
487 |
|
releaseWaiters(phase); |
488 |
|
break; |
505 |
|
} |
506 |
|
|
507 |
|
/** |
508 |
< |
* Arrives at the barrier, and deregisters from it, without |
509 |
< |
* waiting for others. Deregistration reduces number of parties |
508 |
> |
* Arrives at the barrier and deregisters from it without waiting |
509 |
> |
* for others. Deregistration reduces the number of parties |
510 |
|
* required to trip the barrier in future phases. If this phaser |
511 |
|
* has a parent, and deregistration causes this phaser to have |
512 |
< |
* zero parties, this phaser is also deregistered from its parent. |
512 |
> |
* zero parties, this phaser also arrives at and is deregistered |
513 |
> |
* from its parent. It is an unenforced usage error for an |
514 |
> |
* unregistered party to invoke this method. |
515 |
|
* |
516 |
< |
* @return the current barrier phase number upon entry to |
474 |
< |
* this method, or a negative value if terminated |
516 |
> |
* @return the arrival phase number, or a negative value if terminated |
517 |
|
* @throws IllegalStateException if not terminated and the number |
518 |
|
* of registered or unarrived parties would become negative |
519 |
|
*/ |
544 |
|
if (unarrived == 0) { |
545 |
|
if (casState |
546 |
|
(s, |
547 |
< |
trippedStateFor(onAdvance(phase, parties)? -1 : |
547 |
> |
trippedStateFor(onAdvance(phase, parties) ? -1 : |
548 |
|
((phase + 1) & phaseMask), parties))) { |
549 |
|
releaseWaiters(phase); |
550 |
|
break; |
563 |
|
|
564 |
|
/** |
565 |
|
* Arrives at the barrier and awaits others. Equivalent in effect |
566 |
< |
* to {@code awaitAdvance(arrive())}. If you instead need to |
567 |
< |
* await with interruption of timeout, and/or deregister upon |
568 |
< |
* arrival, you can arrange them using analogous constructions. |
566 |
> |
* to {@code awaitAdvance(arrive())}. If you need to await with |
567 |
> |
* interruption or timeout, you can arrange this with an analogous |
568 |
> |
* construction using one of the other forms of the awaitAdvance |
569 |
> |
* method. If instead you need to deregister upon arrival use |
570 |
> |
* {@code arriveAndDeregister}. It is an unenforced usage error |
571 |
> |
* for an unregistered party to invoke this method. |
572 |
|
* |
573 |
< |
* @return the phase on entry to this method |
573 |
> |
* @return the arrival phase number, or a negative number if terminated |
574 |
|
* @throws IllegalStateException if not terminated and the number |
575 |
|
* of unarrived parties would become negative |
576 |
|
*/ |
579 |
|
} |
580 |
|
|
581 |
|
/** |
582 |
< |
* Awaits the phase of the barrier to advance from the given |
583 |
< |
* value, or returns immediately if argument is negative or this |
584 |
< |
* barrier is terminated. |
585 |
< |
* |
586 |
< |
* @param phase the phase on entry to this method |
587 |
< |
* @return the phase on exit from this method |
582 |
> |
* Awaits the phase of the barrier to advance from the given phase |
583 |
> |
* value, returning immediately if the current phase of the |
584 |
> |
* barrier is not equal to the given phase value or this barrier |
585 |
> |
* is terminated. It is an unenforced usage error for an |
586 |
> |
* unregistered party to invoke this method. |
587 |
> |
* |
588 |
> |
* @param phase an arrival phase number, or negative value if |
589 |
> |
* terminated; this argument is normally the value returned by a |
590 |
> |
* previous call to {@code arrive} or its variants |
591 |
> |
* @return the next arrival phase number, or a negative value |
592 |
> |
* if terminated or argument is negative |
593 |
|
*/ |
594 |
|
public int awaitAdvance(int phase) { |
595 |
|
if (phase < 0) |
605 |
|
} |
606 |
|
|
607 |
|
/** |
608 |
< |
* Awaits the phase of the barrier to advance from the given |
609 |
< |
* value, or returns immediately if argument is negative or this |
610 |
< |
* barrier is terminated, or throws InterruptedException if |
611 |
< |
* interrupted while waiting. |
612 |
< |
* |
613 |
< |
* @param phase the phase on entry to this method |
614 |
< |
* @return the phase on exit from this method |
608 |
> |
* Awaits the phase of the barrier to advance from the given phase |
609 |
> |
* value, throwing {@code InterruptedException} if interrupted |
610 |
> |
* while waiting, or returning immediately if the current phase of |
611 |
> |
* the barrier is not equal to the given phase value or this |
612 |
> |
* barrier is terminated. It is an unenforced usage error for an |
613 |
> |
* unregistered party to invoke this method. |
614 |
> |
* |
615 |
> |
* @param phase an arrival phase number, or negative value if |
616 |
> |
* terminated; this argument is normally the value returned by a |
617 |
> |
* previous call to {@code arrive} or its variants |
618 |
> |
* @return the next arrival phase number, or a negative value |
619 |
> |
* if terminated or argument is negative |
620 |
|
* @throws InterruptedException if thread interrupted while waiting |
621 |
|
*/ |
622 |
|
public int awaitAdvanceInterruptibly(int phase) |
633 |
|
} |
634 |
|
|
635 |
|
/** |
636 |
< |
* Awaits the phase of the barrier to advance from the given value |
637 |
< |
* or the given timeout elapses, or returns immediately if |
638 |
< |
* argument is negative or this barrier is terminated. |
639 |
< |
* |
640 |
< |
* @param phase the phase on entry to this method |
641 |
< |
* @return the phase on exit from this method |
636 |
> |
* Awaits the phase of the barrier to advance from the given phase |
637 |
> |
* value or the given timeout to elapse, throwing {@code |
638 |
> |
* InterruptedException} if interrupted while waiting, or |
639 |
> |
* returning immediately if the current phase of the barrier is |
640 |
> |
* not equal to the given phase value or this barrier is |
641 |
> |
* terminated. It is an unenforced usage error for an |
642 |
> |
* unregistered party to invoke this method. |
643 |
> |
* |
644 |
> |
* @param phase an arrival phase number, or negative value if |
645 |
> |
* terminated; this argument is normally the value returned by a |
646 |
> |
* previous call to {@code arrive} or its variants |
647 |
> |
* @param timeout how long to wait before giving up, in units of |
648 |
> |
* {@code unit} |
649 |
> |
* @param unit a {@code TimeUnit} determining how to interpret the |
650 |
> |
* {@code timeout} parameter |
651 |
> |
* @return the next arrival phase number, or a negative value |
652 |
> |
* if terminated or argument is negative |
653 |
|
* @throws InterruptedException if thread interrupted while waiting |
654 |
|
* @throws TimeoutException if timed out while waiting |
655 |
|
*/ |
656 |
< |
public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit) |
656 |
> |
public int awaitAdvanceInterruptibly(int phase, |
657 |
> |
long timeout, TimeUnit unit) |
658 |
|
throws InterruptedException, TimeoutException { |
659 |
|
if (phase < 0) |
660 |
|
return phase; |
703 |
|
} |
704 |
|
|
705 |
|
/** |
639 |
– |
* Returns {@code true} if the current phase number equals the given phase. |
640 |
– |
* |
641 |
– |
* @param phase the phase |
642 |
– |
* @return {@code true} if the current phase number equals the given phase |
643 |
– |
*/ |
644 |
– |
public final boolean hasPhase(int phase) { |
645 |
– |
return phaseOf(getReconciledState()) == phase; |
646 |
– |
} |
647 |
– |
|
648 |
– |
/** |
706 |
|
* Returns the number of parties registered at this barrier. |
707 |
|
* |
708 |
|
* @return the number of parties |
712 |
|
} |
713 |
|
|
714 |
|
/** |
715 |
< |
* Returns the number of parties that have arrived at the current |
716 |
< |
* phase of this barrier. |
715 |
> |
* Returns the number of registered parties that have arrived at |
716 |
> |
* the current phase of this barrier. |
717 |
|
* |
718 |
|
* @return the number of arrived parties |
719 |
|
*/ |
732 |
|
} |
733 |
|
|
734 |
|
/** |
735 |
< |
* Returns the parent of this phaser, or null if none. |
735 |
> |
* Returns the parent of this phaser, or {@code null} if none. |
736 |
|
* |
737 |
< |
* @return the parent of this phaser, or null if none |
737 |
> |
* @return the parent of this phaser, or {@code null} if none |
738 |
|
*/ |
739 |
|
public Phaser getParent() { |
740 |
|
return parent; |
763 |
|
* Overridable method to perform an action upon phase advance, and |
764 |
|
* to control termination. This method is invoked whenever the |
765 |
|
* barrier is tripped (and thus all other waiting parties are |
766 |
< |
* dormant). If it returns true, then, rather than advance the |
767 |
< |
* phase number, this barrier will be set to a final termination |
768 |
< |
* state, and subsequent calls to {@code isTerminated} will |
769 |
< |
* return true. |
766 |
> |
* dormant). If it returns {@code true}, then, rather than advance |
767 |
> |
* the phase number, this barrier will be set to a final |
768 |
> |
* termination state, and subsequent calls to {@link #isTerminated} |
769 |
> |
* will return true. |
770 |
|
* |
771 |
< |
* <p> The default version returns true when the number of |
771 |
> |
* <p>The default version returns {@code true} when the number of |
772 |
|
* registered parties is zero. Normally, overrides that arrange |
773 |
|
* termination for other reasons should also preserve this |
774 |
|
* property. |
775 |
|
* |
776 |
< |
* <p> You may override this method to perform an action with side |
776 |
> |
* <p>You may override this method to perform an action with side |
777 |
|
* effects visible to participating tasks, but it is in general |
778 |
|
* only sensible to do so in designs where all parties register |
779 |
< |
* before any arrive, and all {@code awaitAdvance} at each phase. |
780 |
< |
* Otherwise, you cannot ensure lack of interference. In |
781 |
< |
* particular, this method may be invoked more than once per |
725 |
< |
* transition if other parties successfully register while the |
726 |
< |
* invocation of this method is in progress, thus postponing the |
727 |
< |
* transition until those parties also arrive, re-triggering this |
728 |
< |
* method. |
779 |
> |
* before any arrive, and all {@link #awaitAdvance} at each phase. |
780 |
> |
* Otherwise, you cannot ensure lack of interference from other |
781 |
> |
* parties during the invocation of this method. |
782 |
|
* |
783 |
|
* @param phase the phase number on entering the barrier |
784 |
|
* @param registeredParties the current number of registered parties |
983 |
|
return p; |
984 |
|
} |
985 |
|
|
986 |
< |
// Temporary Unsafe mechanics for preliminary release |
934 |
< |
private static Unsafe getUnsafe() throws Throwable { |
935 |
< |
try { |
936 |
< |
return Unsafe.getUnsafe(); |
937 |
< |
} catch (SecurityException se) { |
938 |
< |
try { |
939 |
< |
return java.security.AccessController.doPrivileged |
940 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
941 |
< |
public Unsafe run() throws Exception { |
942 |
< |
return getUnsafePrivileged(); |
943 |
< |
}}); |
944 |
< |
} catch (java.security.PrivilegedActionException e) { |
945 |
< |
throw e.getCause(); |
946 |
< |
} |
947 |
< |
} |
948 |
< |
} |
986 |
> |
// Unsafe mechanics |
987 |
|
|
988 |
< |
private static Unsafe getUnsafePrivileged() |
989 |
< |
throws NoSuchFieldException, IllegalAccessException { |
990 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
953 |
< |
f.setAccessible(true); |
954 |
< |
return (Unsafe) f.get(null); |
955 |
< |
} |
988 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
989 |
> |
private static final long stateOffset = |
990 |
> |
objectFieldOffset("state", Phaser.class); |
991 |
|
|
992 |
< |
private static long fieldOffset(String fieldName) |
993 |
< |
throws NoSuchFieldException { |
959 |
< |
return UNSAFE.objectFieldOffset |
960 |
< |
(Phaser.class.getDeclaredField(fieldName)); |
992 |
> |
private final boolean casState(long cmp, long val) { |
993 |
> |
return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val); |
994 |
|
} |
995 |
|
|
996 |
< |
static final Unsafe UNSAFE; |
964 |
< |
static final long stateOffset; |
965 |
< |
|
966 |
< |
static { |
996 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
997 |
|
try { |
998 |
< |
UNSAFE = getUnsafe(); |
999 |
< |
stateOffset = fieldOffset("state"); |
1000 |
< |
} catch (Throwable e) { |
1001 |
< |
throw new RuntimeException("Could not initialize intrinsics", e); |
998 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
999 |
> |
} catch (NoSuchFieldException e) { |
1000 |
> |
// Convert Exception to corresponding Error |
1001 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1002 |
> |
error.initCause(e); |
1003 |
> |
throw error; |
1004 |
|
} |
1005 |
|
} |
1006 |
|
|
1007 |
< |
final boolean casState(long cmp, long val) { |
1008 |
< |
return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val); |
1007 |
> |
/** |
1008 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1009 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1010 |
> |
* into a jdk. |
1011 |
> |
* |
1012 |
> |
* @return a sun.misc.Unsafe |
1013 |
> |
*/ |
1014 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1015 |
> |
try { |
1016 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1017 |
> |
} catch (SecurityException se) { |
1018 |
> |
try { |
1019 |
> |
return java.security.AccessController.doPrivileged |
1020 |
> |
(new java.security |
1021 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1022 |
> |
public sun.misc.Unsafe run() throws Exception { |
1023 |
> |
java.lang.reflect.Field f = sun.misc |
1024 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1025 |
> |
f.setAccessible(true); |
1026 |
> |
return (sun.misc.Unsafe) f.get(null); |
1027 |
> |
}}); |
1028 |
> |
} catch (java.security.PrivilegedActionException e) { |
1029 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1030 |
> |
e.getCause()); |
1031 |
> |
} |
1032 |
> |
} |
1033 |
|
} |
1034 |
|
} |