298 |
|
* use two of them, alternating across even and odd phases. |
299 |
|
* Subphasers share queues with root to speed up releases. |
300 |
|
*/ |
301 |
< |
private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>(); |
302 |
< |
private final AtomicReference<QNode> oddQ = new AtomicReference<QNode>(); |
301 |
> |
private final AtomicReference<QNode> evenQ; |
302 |
> |
private final AtomicReference<QNode> oddQ; |
303 |
|
|
304 |
|
private AtomicReference<QNode> queueFor(int phase) { |
305 |
< |
Phaser r = root; |
306 |
< |
return ((phase & 1) == 0) ? r.evenQ : r.oddQ; |
305 |
> |
return ((phase & 1) == 0) ? evenQ : oddQ; |
306 |
|
} |
307 |
|
|
308 |
|
/** |
324 |
|
while ((phase = phaseOf(s)) >= 0 && |
325 |
|
(rootPhase = phaseOf(root.state)) != phase && |
326 |
|
(rootPhase < 0 || unarrivedOf(s) == 0)) { |
327 |
< |
long parentState = par.getReconciledState(); |
328 |
< |
int parentPhase = phaseOf(parentState); |
329 |
< |
int parties = partiesOf(s); |
330 |
< |
long next = trippedStateFor(parentPhase, parties); |
331 |
< |
if (phaseOf(root.state) == rootPhase && |
333 |
< |
parentPhase != phase && |
334 |
< |
state == s && casState(s, next)) { |
335 |
< |
releaseWaiters(phase); |
336 |
< |
if (parties == 0) // exit if the final deregistration |
337 |
< |
break; |
327 |
> |
int parentPhase = phaseOf(par.getReconciledState()); |
328 |
> |
if (parentPhase != phase) { |
329 |
> |
long next = trippedStateFor(parentPhase, partiesOf(s)); |
330 |
> |
if (state == s) |
331 |
> |
UNSAFE.compareAndSwapLong(this, stateOffset, s, next); |
332 |
|
} |
333 |
|
s = state; |
334 |
|
} |
342 |
|
* phaser will need to first register for it. |
343 |
|
*/ |
344 |
|
public Phaser() { |
345 |
< |
this(null); |
345 |
> |
this(null, 0); |
346 |
|
} |
347 |
|
|
348 |
|
/** |
366 |
|
* @param parent the parent phaser |
367 |
|
*/ |
368 |
|
public Phaser(Phaser parent) { |
369 |
< |
int phase = 0; |
376 |
< |
this.parent = parent; |
377 |
< |
if (parent != null) { |
378 |
< |
this.root = parent.root; |
379 |
< |
phase = parent.register(); |
380 |
< |
} |
381 |
< |
else |
382 |
< |
this.root = this; |
383 |
< |
this.state = trippedStateFor(phase, 0); |
369 |
> |
this(parent, 0); |
370 |
|
} |
371 |
|
|
372 |
|
/** |
383 |
|
public Phaser(Phaser parent, int parties) { |
384 |
|
if (parties < 0 || parties > ushortMask) |
385 |
|
throw new IllegalArgumentException("Illegal number of parties"); |
386 |
< |
int phase = 0; |
386 |
> |
int phase; |
387 |
|
this.parent = parent; |
388 |
|
if (parent != null) { |
389 |
< |
this.root = parent.root; |
389 |
> |
Phaser r = parent.root; |
390 |
> |
this.root = r; |
391 |
> |
this.evenQ = r.evenQ; |
392 |
> |
this.oddQ = r.oddQ; |
393 |
|
phase = parent.register(); |
394 |
|
} |
395 |
< |
else |
395 |
> |
else { |
396 |
|
this.root = this; |
397 |
+ |
this.evenQ = new AtomicReference<QNode>(); |
398 |
+ |
this.oddQ = new AtomicReference<QNode>(); |
399 |
+ |
phase = 0; |
400 |
+ |
} |
401 |
|
this.state = trippedStateFor(phase, parties); |
402 |
|
} |
403 |
|
|
404 |
|
/** |
405 |
|
* Adds a new unarrived party to this phaser. |
406 |
|
* If an ongoing invocation of {@link #onAdvance} is in progress, |
407 |
< |
* this method waits until its completion before registering. |
407 |
> |
* this method may wait until its completion before registering. |
408 |
|
* |
409 |
|
* @return the arrival phase number to which this registration applied |
410 |
|
* @throws IllegalStateException if attempting to register more |
417 |
|
/** |
418 |
|
* Adds the given number of new unarrived parties to this phaser. |
419 |
|
* If an ongoing invocation of {@link #onAdvance} is in progress, |
420 |
< |
* this method waits until its completion before registering. |
420 |
> |
* this method may wait until its completion before registering. |
421 |
|
* |
422 |
|
* @param parties the number of additional parties required to trip barrier |
423 |
|
* @return the arrival phase number to which this registration applied |
445 |
|
int u = unarrivedOf(s); |
446 |
|
int unarrived = u + registrations; |
447 |
|
int parties = p + registrations; |
448 |
< |
if (par == null || phase == phaseOf(root.state)) { |
449 |
< |
if (parties > ushortMask || unarrived > ushortMask) |
450 |
< |
throw new IllegalStateException(badBounds(parties, |
451 |
< |
unarrived)); |
452 |
< |
else if (p != 0 && u == 0) // back off if advancing |
453 |
< |
Thread.yield(); // not worth actually blocking |
454 |
< |
else if (casState(s, stateFor(phase, parties, unarrived))) |
448 |
> |
if (u == 0 && p != 0) // if tripped, wait for advance |
449 |
> |
untimedWait(phase); |
450 |
> |
else if (parties > ushortMask) |
451 |
> |
throw new IllegalStateException(badBounds(parties, unarrived)); |
452 |
> |
else if (par == null || phaseOf(root.state) == phase) { |
453 |
> |
long next = stateFor(phase, parties, unarrived); |
454 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) |
455 |
|
break; |
456 |
|
} |
457 |
|
} |
475 |
|
while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) { |
476 |
|
int parties = partiesOf(s); |
477 |
|
int unarrived = unarrivedOf(s) - 1; |
478 |
< |
if (parties == 0 || unarrived < 0) |
479 |
< |
throw new IllegalStateException(badBounds(parties, |
480 |
< |
unarrived)); |
488 |
< |
else if (unarrived > 0) { // Not the last arrival |
489 |
< |
if (casState(s, s - 1)) // s-1 adds one arrival |
490 |
< |
break; |
478 |
> |
if (unarrived > 0) { // Not the last arrival |
479 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s - 1)) |
480 |
> |
break; // s-1 adds one arrival |
481 |
|
} |
482 |
+ |
else if (unarrived < 0) |
483 |
+ |
throw new IllegalStateException(badBounds(parties, unarrived)); |
484 |
|
else if (par == null) { // directly trip |
485 |
< |
if (casState(s, trippedStateFor(onAdvance(phase, parties) ? -1 : |
486 |
< |
((phase + 1) & phaseMask), |
487 |
< |
parties))) { |
485 |
> |
long next = trippedStateFor(onAdvance(phase, parties) ? -1 : |
486 |
> |
((phase + 1) & phaseMask), |
487 |
> |
parties); |
488 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) { |
489 |
|
releaseWaiters(phase); |
490 |
|
break; |
491 |
|
} |
492 |
|
} |
493 |
< |
else if (phaseOf(root.state) == phase && casState(s, s - 1)) { |
493 |
> |
else if (phaseOf(root.state) == phase && |
494 |
> |
UNSAFE.compareAndSwapLong(this, stateOffset, s, s - 1)) { |
495 |
|
par.arrive(); // cascade to parent |
496 |
|
reconcileState(); |
497 |
|
break; |
521 |
|
while ((phase = phaseOf(s = par==null? state:reconcileState())) >= 0) { |
522 |
|
int parties = partiesOf(s) - 1; |
523 |
|
int unarrived = unarrivedOf(s) - 1; |
524 |
< |
if (parties < 0 || unarrived < 0) |
525 |
< |
throw new IllegalStateException(badBounds(parties, |
526 |
< |
unarrived)); |
533 |
< |
else if (unarrived > 0) { |
534 |
< |
if (casState(s, stateFor(phase, parties, unarrived))) |
524 |
> |
if (unarrived > 0) { |
525 |
> |
long next = stateFor(phase, parties, unarrived); |
526 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) |
527 |
|
break; |
528 |
|
} |
529 |
+ |
else if (unarrived < 0) |
530 |
+ |
throw new IllegalStateException(badBounds(parties, unarrived)); |
531 |
|
else if (par == null) { |
532 |
< |
if (casState(s, trippedStateFor(onAdvance(phase, parties)? -1: |
533 |
< |
(phase + 1) & phaseMask, |
534 |
< |
parties))) { |
532 |
> |
long next = trippedStateFor(onAdvance(phase, parties)? -1: |
533 |
> |
(phase + 1) & phaseMask, |
534 |
> |
parties); |
535 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) { |
536 |
|
releaseWaiters(phase); |
537 |
|
break; |
538 |
|
} |
539 |
|
} |
540 |
< |
else if (phaseOf(root.state) == phase && |
541 |
< |
casState(s, stateFor(phase, parties, 0))) { |
542 |
< |
if (parties == 0) |
543 |
< |
par.arriveAndDeregister(); |
544 |
< |
else |
545 |
< |
par.arrive(); |
546 |
< |
reconcileState(); |
547 |
< |
break; |
540 |
> |
else if (phaseOf(root.state) == phase) { |
541 |
> |
long next = stateFor(phase, parties, 0); |
542 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) { |
543 |
> |
if (parties == 0) |
544 |
> |
par.arriveAndDeregister(); |
545 |
> |
else |
546 |
> |
par.arrive(); |
547 |
> |
reconcileState(); |
548 |
> |
break; |
549 |
> |
} |
550 |
|
} |
551 |
|
} |
552 |
|
return phase; |
573 |
|
* Awaits the phase of the barrier to advance from the given phase |
574 |
|
* value, returning immediately if the current phase of the |
575 |
|
* barrier is not equal to the given phase value or this barrier |
576 |
< |
* is terminated. It is an unenforced usage error for an |
580 |
< |
* unregistered party to invoke this method. |
576 |
> |
* is terminated. |
577 |
|
* |
578 |
|
* @param phase an arrival phase number, or negative value if |
579 |
|
* terminated; this argument is normally the value returned by a |
595 |
|
* value, throwing {@code InterruptedException} if interrupted |
596 |
|
* while waiting, or returning immediately if the current phase of |
597 |
|
* the barrier is not equal to the given phase value or this |
598 |
< |
* barrier is terminated. It is an unenforced usage error for an |
603 |
< |
* unregistered party to invoke this method. |
598 |
> |
* barrier is terminated. |
599 |
|
* |
600 |
|
* @param phase an arrival phase number, or negative value if |
601 |
|
* terminated; this argument is normally the value returned by a |
620 |
|
* InterruptedException} if interrupted while waiting, or |
621 |
|
* returning immediately if the current phase of the barrier is |
622 |
|
* not equal to the given phase value or this barrier is |
623 |
< |
* terminated. It is an unenforced usage error for an |
629 |
< |
* unregistered party to invoke this method. |
623 |
> |
* terminated. |
624 |
|
* |
625 |
|
* @param phase an arrival phase number, or negative value if |
626 |
|
* terminated; this argument is normally the value returned by a |
657 |
|
Phaser r = root; // force at root then reconcile |
658 |
|
long s; |
659 |
|
while (phaseOf(s = r.state) >= 0) |
660 |
< |
r.casState(s, stateFor(-1, partiesOf(s), unarrivedOf(s))); |
660 |
> |
UNSAFE.compareAndSwapLong(r, stateOffset, s, |
661 |
> |
stateFor(-1, partiesOf(s), |
662 |
> |
unarrivedOf(s))); |
663 |
|
reconcileState(); |
664 |
|
releaseWaiters(0); // ensure wakeups on both queues |
665 |
|
releaseWaiters(1); |
746 |
|
* which case no advance occurs. |
747 |
|
* |
748 |
|
* <p>The arguments to this method provide the state of the phaser |
749 |
< |
* prevailing for the current transition. (When called from within |
750 |
< |
* an implementation of {@code onAdvance} the values returned by |
751 |
< |
* methods such as {@code getPhase} may or may not reliably |
752 |
< |
* indicate the state to which this transition applies.) |
749 |
> |
* prevailing for the current transition. The results and effects |
750 |
> |
* of invoking phase-related methods (including {@code getPhase} |
751 |
> |
* as well as arrival, registration, and waiting methods) from |
752 |
> |
* within {@code onAdvance} are unspecified and should not be |
753 |
> |
* relied on. Similarly, while it is possible to override this |
754 |
> |
* method to produce side-effects visible to participating tasks, |
755 |
> |
* it is in general safe to do so only in designs in which all |
756 |
> |
* parties register before any arrive, and all {@link |
757 |
> |
* #awaitAdvance} at each phase. |
758 |
|
* |
759 |
|
* <p>The default version returns {@code true} when the number of |
760 |
|
* registered parties is zero. Normally, overrides that arrange |
880 |
|
} |
881 |
|
|
882 |
|
/** |
883 |
+ |
* The number of times to spin before blocking waiting for advance. |
884 |
+ |
*/ |
885 |
+ |
static final int MAX_SPINS = |
886 |
+ |
Runtime.getRuntime().availableProcessors() == 1 ? 0 : 1 << 8; |
887 |
+ |
|
888 |
+ |
/** |
889 |
|
* Enqueues node and waits unless aborted or signalled. |
890 |
|
* |
891 |
|
* @return current phase |
894 |
|
QNode node = null; |
895 |
|
boolean queued = false; |
896 |
|
boolean interrupted = false; |
897 |
+ |
int spins = MAX_SPINS; |
898 |
|
int p; |
899 |
|
while ((p = getPhase()) == phase) { |
900 |
|
if (Thread.interrupted()) |
901 |
|
interrupted = true; |
902 |
+ |
else if (spins > 0) { |
903 |
+ |
if (--spins == 0) |
904 |
+ |
Thread.yield(); |
905 |
+ |
} |
906 |
|
else if (node == null) |
907 |
|
node = new QNode(this, phase, false, false, 0, 0); |
908 |
|
else if (!queued) |
926 |
|
QNode node = null; |
927 |
|
boolean queued = false; |
928 |
|
boolean interrupted = false; |
929 |
+ |
int spins = MAX_SPINS; |
930 |
|
int p; |
931 |
|
while ((p = getPhase()) == phase && !interrupted) { |
932 |
|
if (Thread.interrupted()) |
933 |
|
interrupted = true; |
934 |
+ |
else if (spins > 0) { |
935 |
+ |
if (--spins == 0) |
936 |
+ |
Thread.yield(); |
937 |
+ |
} |
938 |
|
else if (node == null) |
939 |
|
node = new QNode(this, phase, true, false, 0, 0); |
940 |
|
else if (!queued) |
961 |
|
QNode node = null; |
962 |
|
boolean queued = false; |
963 |
|
boolean interrupted = false; |
964 |
+ |
int spins = MAX_SPINS; |
965 |
|
int p; |
966 |
|
while ((p = getPhase()) == phase && !interrupted) { |
967 |
|
if (Thread.interrupted()) |
968 |
|
interrupted = true; |
969 |
|
else if (nanos - (System.nanoTime() - startTime) <= 0) |
970 |
|
break; |
971 |
+ |
else if (spins > 0) { |
972 |
+ |
if (--spins == 0) |
973 |
+ |
Thread.yield(); |
974 |
+ |
} |
975 |
|
else if (node == null) |
976 |
|
node = new QNode(this, phase, true, true, startTime, nanos); |
977 |
|
else if (!queued) |
996 |
|
private static final long stateOffset = |
997 |
|
objectFieldOffset("state", Phaser.class); |
998 |
|
|
977 |
– |
private final boolean casState(long cmp, long val) { |
978 |
– |
return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val); |
979 |
– |
} |
980 |
– |
|
999 |
|
private static long objectFieldOffset(String field, Class<?> klazz) { |
1000 |
|
try { |
1001 |
|
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |