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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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|
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package jsr166y; |
75 |
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* </ul> |
76 |
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* |
77 |
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* <p> <b>Termination.</b> A phaser may enter a <em>termination</em> |
78 |
< |
* state in which all synchronization methods immediately return |
79 |
< |
* without updating phaser state or waiting for advance, and |
80 |
< |
* indicating (via a negative phase value) that execution is complete. |
78 |
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* state, that may be checked using method {@link #isTerminated}. Upon |
79 |
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* termination, all synchronization methods immediately return without |
80 |
> |
* waiting for advance, as indicated by a negative return value. |
81 |
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* Similarly, attempts to register upon termination have no effect. |
82 |
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* Termination is triggered when an invocation of {@code onAdvance} |
83 |
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* returns {@code true}. The default implementation returns {@code |
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* true} if a deregistration has caused the number of registered |
97 |
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* increase throughput even though it incurs greater per-operation |
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* overhead. |
99 |
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* |
100 |
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* <p>In a tree of tiered phasers, registration and deregistration of |
101 |
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* child phasers with their parent are managed automatically. |
102 |
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* Whenever the number of registered parties of a child phaser becomes |
103 |
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* non-zero (as established in the {@link #Phaser(Phaser,int)} |
104 |
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* constructor, {@link #register}, or {@link #bulkRegister}), the |
105 |
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* child phaser is registered with its parent. Whenever the number of |
106 |
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* registered parties becomes zero as the result of an invocation of |
107 |
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* {@link #arriveAndDeregister}, the child phaser is deregistered |
108 |
+ |
* from its parent. |
109 |
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* |
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* <p><b>Monitoring.</b> While synchronization methods may be invoked |
111 |
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* only by registered parties, the current state of a phaser may be |
112 |
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* monitored by any caller. At any given moment there are {@link |
130 |
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* void runTasks(List<Runnable> tasks) { |
131 |
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* final Phaser phaser = new Phaser(1); // "1" to register self |
132 |
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* // create and start threads |
133 |
< |
* for (Runnable task : tasks) { |
133 |
> |
* for (final Runnable task : tasks) { |
134 |
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* phaser.register(); |
135 |
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* new Thread() { |
136 |
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* public void run() { |
237 |
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*/ |
238 |
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|
239 |
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/** |
240 |
< |
* Primary state representation, holding four fields: |
240 |
> |
* Primary state representation, holding four bit-fields: |
241 |
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* |
242 |
< |
* * unarrived -- the number of parties yet to hit barrier (bits 0-15) |
243 |
< |
* * parties -- the number of parties to wait (bits 16-31) |
244 |
< |
* * phase -- the generation of the barrier (bits 32-62) |
245 |
< |
* * terminated -- set if barrier is terminated (bit 63 / sign) |
242 |
> |
* unarrived -- the number of parties yet to hit barrier (bits 0-15) |
243 |
> |
* parties -- the number of parties to wait (bits 16-31) |
244 |
> |
* phase -- the generation of the barrier (bits 32-62) |
245 |
> |
* terminated -- set if barrier is terminated (bit 63 / sign) |
246 |
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* |
247 |
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* Except that a phaser with no registered parties is |
248 |
< |
* distinguished with the otherwise illegal state of having zero |
248 |
> |
* distinguished by the otherwise illegal state of having zero |
249 |
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* parties and one unarrived parties (encoded as EMPTY below). |
250 |
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* |
251 |
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* To efficiently maintain atomicity, these values are packed into |
260 |
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* parent. |
261 |
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* |
262 |
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* The phase of a subphaser is allowed to lag that of its |
263 |
< |
* ancestors until it is actually accessed. Method reconcileState |
264 |
< |
* is usually attempted only only when the number of unarrived |
254 |
< |
* parties appears to be zero, which indicates a potential lag in |
255 |
< |
* updating phase after the root advanced. |
263 |
> |
* ancestors until it is actually accessed -- see method |
264 |
> |
* reconcileState. |
265 |
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*/ |
266 |
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private volatile long state; |
267 |
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|
268 |
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private static final int MAX_PARTIES = 0xffff; |
269 |
< |
private static final int MAX_PHASE = 0x7fffffff; |
269 |
> |
private static final int MAX_PHASE = Integer.MAX_VALUE; |
270 |
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private static final int PARTIES_SHIFT = 16; |
271 |
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private static final int PHASE_SHIFT = 32; |
272 |
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private static final int UNARRIVED_MASK = 0xffff; // to mask ints |
276 |
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// some special values |
277 |
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private static final int ONE_ARRIVAL = 1; |
278 |
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private static final int ONE_PARTY = 1 << PARTIES_SHIFT; |
279 |
+ |
private static final int ONE_DEREGISTER = ONE_ARRIVAL|ONE_PARTY; |
280 |
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private static final int EMPTY = 1; |
281 |
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|
282 |
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// The following unpacking methods are usually manually inlined |
283 |
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|
284 |
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private static int unarrivedOf(long s) { |
285 |
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int counts = (int)s; |
286 |
< |
return (counts == EMPTY) ? 0 : counts & UNARRIVED_MASK; |
286 |
> |
return (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK); |
287 |
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} |
288 |
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|
289 |
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private static int partiesOf(long s) { |
290 |
< |
int counts = (int)s; |
281 |
< |
return (counts == EMPTY) ? 0 : counts >>> PARTIES_SHIFT; |
290 |
> |
return (int)s >>> PARTIES_SHIFT; |
291 |
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} |
292 |
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|
293 |
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private static int phaseOf(long s) { |
294 |
< |
return (int) (s >>> PHASE_SHIFT); |
294 |
> |
return (int)(s >>> PHASE_SHIFT); |
295 |
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} |
296 |
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|
297 |
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private static int arrivedOf(long s) { |
344 |
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* Manually tuned to speed up and minimize race windows for the |
345 |
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* common case of just decrementing unarrived field. |
346 |
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* |
347 |
< |
* @param deregister false for arrive, true for arriveAndDeregister |
347 |
> |
* @param adjust value to subtract from state; |
348 |
> |
* ONE_ARRIVAL for arrive, |
349 |
> |
* ONE_DEREGISTER for arriveAndDeregister |
350 |
|
*/ |
351 |
< |
private int doArrive(boolean deregister) { |
352 |
< |
int adj = deregister ? ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL; |
353 |
< |
long s; |
354 |
< |
int phase; |
355 |
< |
while ((phase = (int)((s = state) >>> PHASE_SHIFT)) >= 0) { |
351 |
> |
private int doArrive(int adjust) { |
352 |
> |
final Phaser root = this.root; |
353 |
> |
for (;;) { |
354 |
> |
long s = (root == this) ? state : reconcileState(); |
355 |
> |
int phase = (int)(s >>> PHASE_SHIFT); |
356 |
> |
if (phase < 0) |
357 |
> |
return phase; |
358 |
|
int counts = (int)s; |
359 |
< |
int unarrived = counts & UNARRIVED_MASK; |
360 |
< |
if (counts == EMPTY || unarrived == 0) { |
361 |
< |
if (reconcileState() == s) |
362 |
< |
throw new IllegalStateException(badArrive(s)); |
350 |
< |
} |
351 |
< |
else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) { |
359 |
> |
int unarrived = (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK); |
360 |
> |
if (unarrived <= 0) |
361 |
> |
throw new IllegalStateException(badArrive(s)); |
362 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adjust)) { |
363 |
|
if (unarrived == 1) { |
364 |
< |
long n = s & PARTIES_MASK; // unshifted parties field |
365 |
< |
int u = ((int)n) >>> PARTIES_SHIFT; |
366 |
< |
Phaser par = parent; |
367 |
< |
if (par != null) { |
357 |
< |
par.doArrive(u == 0); |
358 |
< |
reconcileState(); |
359 |
< |
} |
360 |
< |
else { |
361 |
< |
n |= (((long)((phase+1) & MAX_PHASE)) << PHASE_SHIFT); |
362 |
< |
if (onAdvance(phase, u)) |
364 |
> |
long n = s & PARTIES_MASK; // base of next state |
365 |
> |
int nextUnarrived = (int)n >>> PARTIES_SHIFT; |
366 |
> |
if (root == this) { |
367 |
> |
if (onAdvance(phase, nextUnarrived)) |
368 |
|
n |= TERMINATION_BIT; |
369 |
< |
else if (u == 0) |
370 |
< |
n |= EMPTY; // reset to unregistered |
369 |
> |
else if (nextUnarrived == 0) |
370 |
> |
n |= EMPTY; |
371 |
|
else |
372 |
< |
n |= (long)u; // reset unarr to parties |
373 |
< |
// assert state == s || isTerminated(); |
372 |
> |
n |= nextUnarrived; |
373 |
> |
int nextPhase = (phase + 1) & MAX_PHASE; |
374 |
> |
n |= (long)nextPhase << PHASE_SHIFT; |
375 |
|
UNSAFE.compareAndSwapLong(this, stateOffset, s, n); |
376 |
|
releaseWaiters(phase); |
377 |
|
} |
378 |
+ |
else if (nextUnarrived == 0) { // propagate deregistration |
379 |
+ |
phase = parent.doArrive(ONE_DEREGISTER); |
380 |
+ |
UNSAFE.compareAndSwapLong(this, stateOffset, |
381 |
+ |
s, s | EMPTY); |
382 |
+ |
} |
383 |
+ |
else |
384 |
+ |
phase = parent.doArrive(ONE_ARRIVAL); |
385 |
|
} |
386 |
< |
break; |
386 |
> |
return phase; |
387 |
|
} |
388 |
|
} |
376 |
– |
return phase; |
389 |
|
} |
390 |
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|
391 |
|
/** |
396 |
|
*/ |
397 |
|
private int doRegister(int registrations) { |
398 |
|
// adjustment to state |
399 |
< |
long adj = ((long)registrations << PARTIES_SHIFT) | registrations; |
400 |
< |
Phaser par = parent; |
399 |
> |
long adjust = ((long)registrations << PARTIES_SHIFT) | registrations; |
400 |
> |
final Phaser parent = this.parent; |
401 |
|
int phase; |
402 |
|
for (;;) { |
403 |
< |
long s = state; |
403 |
> |
long s = (parent == null) ? state : reconcileState(); |
404 |
|
int counts = (int)s; |
405 |
|
int parties = counts >>> PARTIES_SHIFT; |
406 |
|
int unarrived = counts & UNARRIVED_MASK; |
407 |
|
if (registrations > MAX_PARTIES - parties) |
408 |
|
throw new IllegalStateException(badRegister(s)); |
409 |
< |
else if ((phase = (int)(s >>> PHASE_SHIFT)) < 0) |
409 |
> |
phase = (int)(s >>> PHASE_SHIFT); |
410 |
> |
if (phase < 0) |
411 |
|
break; |
412 |
< |
else if (counts != EMPTY) { // not 1st registration |
413 |
< |
if (par == null || reconcileState() == s) { |
412 |
> |
if (counts != EMPTY) { // not 1st registration |
413 |
> |
if (parent == null || reconcileState() == s) { |
414 |
|
if (unarrived == 0) // wait out advance |
415 |
|
root.internalAwaitAdvance(phase, null); |
416 |
|
else if (UNSAFE.compareAndSwapLong(this, stateOffset, |
417 |
< |
s, s + adj)) |
417 |
> |
s, s + adjust)) |
418 |
|
break; |
419 |
|
} |
420 |
|
} |
421 |
< |
else if (par == null) { // 1st root registration |
422 |
< |
long next = (((long) phase) << PHASE_SHIFT) | adj; |
421 |
> |
else if (parent == null) { // 1st root registration |
422 |
> |
long next = ((long)phase << PHASE_SHIFT) | adjust; |
423 |
|
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) |
424 |
|
break; |
425 |
|
} |
426 |
|
else { |
427 |
|
synchronized (this) { // 1st sub registration |
428 |
|
if (state == s) { // recheck under lock |
429 |
< |
par.doRegister(1); |
430 |
< |
do { // force current phase |
429 |
> |
phase = parent.doRegister(1); |
430 |
> |
if (phase < 0) |
431 |
> |
break; |
432 |
> |
// finish registration whenever parent registration |
433 |
> |
// succeeded, even when racing with termination, |
434 |
> |
// since these are part of the same "transaction". |
435 |
> |
while (!UNSAFE.compareAndSwapLong |
436 |
> |
(this, stateOffset, s, |
437 |
> |
((long)phase << PHASE_SHIFT) | adjust)) { |
438 |
> |
s = state; |
439 |
|
phase = (int)(root.state >>> PHASE_SHIFT); |
440 |
< |
// assert phase < 0 || (int)state == EMPTY; |
441 |
< |
} while (!UNSAFE.compareAndSwapLong |
421 |
< |
(this, stateOffset, state, |
422 |
< |
(((long) phase) << PHASE_SHIFT) | adj)); |
440 |
> |
// assert (int)s == EMPTY; |
441 |
> |
} |
442 |
|
break; |
443 |
|
} |
444 |
|
} |
449 |
|
|
450 |
|
/** |
451 |
|
* Resolves lagged phase propagation from root if necessary. |
452 |
+ |
* Reconciliation normally occurs when root has advanced but |
453 |
+ |
* subphasers have not yet done so, in which case they must finish |
454 |
+ |
* their own advance by setting unarrived to parties (or if |
455 |
+ |
* parties is zero, resetting to unregistered EMPTY state). |
456 |
+ |
* However, this method may also be called when "floating" |
457 |
+ |
* subphasers with possibly some unarrived parties are merely |
458 |
+ |
* catching up to current phase, in which case counts are |
459 |
+ |
* unaffected. |
460 |
+ |
* |
461 |
+ |
* @return reconciled state |
462 |
|
*/ |
463 |
|
private long reconcileState() { |
464 |
< |
Phaser rt = root; |
464 |
> |
final Phaser root = this.root; |
465 |
|
long s = state; |
466 |
< |
if (rt != this) { |
467 |
< |
int phase; |
468 |
< |
while ((phase = (int)(rt.state >>> PHASE_SHIFT)) != |
469 |
< |
(int)(s >>> PHASE_SHIFT)) { |
470 |
< |
// assert phase < 0 || unarrivedOf(s) == 0 |
471 |
< |
long t; // to reread s |
472 |
< |
long p = s & PARTIES_MASK; // unshifted parties field |
473 |
< |
long n = (((long) phase) << PHASE_SHIFT) | p; |
474 |
< |
if (phase >= 0) { |
475 |
< |
if (p == 0L) |
476 |
< |
n |= EMPTY; // reset to empty |
477 |
< |
else |
478 |
< |
n |= p >>> PARTIES_SHIFT; // set unarr to parties |
450 |
< |
} |
451 |
< |
if ((t = state) == s && |
452 |
< |
UNSAFE.compareAndSwapLong(this, stateOffset, s, s = n)) |
453 |
< |
break; |
454 |
< |
s = t; |
455 |
< |
} |
466 |
> |
if (root != this) { |
467 |
> |
int phase, u, p; |
468 |
> |
// CAS root phase with current parties; possibly trip unarrived |
469 |
> |
while ((phase = (int)(root.state >>> PHASE_SHIFT)) != |
470 |
> |
(int)(s >>> PHASE_SHIFT) && |
471 |
> |
!UNSAFE.compareAndSwapLong |
472 |
> |
(this, stateOffset, s, |
473 |
> |
s = (((long)phase << PHASE_SHIFT) | |
474 |
> |
(s & PARTIES_MASK) | |
475 |
> |
((p = (int)s >>> PARTIES_SHIFT) == 0 ? EMPTY : |
476 |
> |
((u = (int)s & UNARRIVED_MASK) == 0 && phase >= 0) ? |
477 |
> |
p : u)))) |
478 |
> |
s = state; |
479 |
|
} |
480 |
|
return s; |
481 |
|
} |
513 |
|
|
514 |
|
/** |
515 |
|
* Creates a new phaser with the given parent and number of |
516 |
< |
* registered unarrived parties. Registration and deregistration |
517 |
< |
* of this child phaser with its parent are managed automatically. |
518 |
< |
* If the given parent is non-null, whenever this child phaser has |
496 |
< |
* any registered parties (as established in this constructor, |
497 |
< |
* {@link #register}, or {@link #bulkRegister}), this child phaser |
498 |
< |
* is registered with its parent. Whenever the number of |
499 |
< |
* registered parties becomes zero as the result of an invocation |
500 |
< |
* of {@link #arriveAndDeregister}, this child phaser is |
501 |
< |
* deregistered from its parent. |
516 |
> |
* registered unarrived parties. When the given parent is non-null |
517 |
> |
* and the given number of parties is greater than zero, this |
518 |
> |
* child phaser is registered with its parent. |
519 |
|
* |
520 |
|
* @param parent the parent phaser |
521 |
|
* @param parties the number of parties required to advance to the |
529 |
|
int phase = 0; |
530 |
|
this.parent = parent; |
531 |
|
if (parent != null) { |
532 |
< |
Phaser r = parent.root; |
533 |
< |
this.root = r; |
534 |
< |
this.evenQ = r.evenQ; |
535 |
< |
this.oddQ = r.oddQ; |
532 |
> |
final Phaser root = parent.root; |
533 |
> |
this.root = root; |
534 |
> |
this.evenQ = root.evenQ; |
535 |
> |
this.oddQ = root.oddQ; |
536 |
|
if (parties != 0) |
537 |
|
phase = parent.doRegister(1); |
538 |
|
} |
541 |
|
this.evenQ = new AtomicReference<QNode>(); |
542 |
|
this.oddQ = new AtomicReference<QNode>(); |
543 |
|
} |
544 |
< |
this.state = (parties == 0) ? ((long) EMPTY) : |
545 |
< |
((((long) phase) << PHASE_SHIFT) | |
546 |
< |
(((long) parties) << PARTIES_SHIFT) | |
547 |
< |
((long) parties)); |
544 |
> |
this.state = (parties == 0) ? (long)EMPTY : |
545 |
> |
((long)phase << PHASE_SHIFT) | |
546 |
> |
((long)parties << PARTIES_SHIFT) | |
547 |
> |
((long)parties); |
548 |
|
} |
549 |
|
|
550 |
|
/** |
552 |
|
* invocation of {@link #onAdvance} is in progress, this method |
553 |
|
* may await its completion before returning. If this phaser has |
554 |
|
* a parent, and this phaser previously had no registered parties, |
555 |
< |
* this phaser is also registered with its parent. |
556 |
< |
* |
557 |
< |
* @return the arrival phase number to which this registration applied |
555 |
> |
* this child phaser is also registered with its parent. If |
556 |
> |
* this phaser is terminated, the attempt to register has |
557 |
> |
* no effect, and a negative value is returned. |
558 |
> |
* |
559 |
> |
* @return the arrival phase number to which this registration |
560 |
> |
* applied. If this value is negative, then this phaser has |
561 |
> |
* terminated, in which case registration has no effect. |
562 |
|
* @throws IllegalStateException if attempting to register more |
563 |
|
* than the maximum supported number of parties |
564 |
|
*/ |
570 |
|
* Adds the given number of new unarrived parties to this phaser. |
571 |
|
* If an ongoing invocation of {@link #onAdvance} is in progress, |
572 |
|
* this method may await its completion before returning. If this |
573 |
< |
* phaser has a parent, and the given number of parities is |
574 |
< |
* greater than zero, and this phaser previously had no registered |
575 |
< |
* parties, this phaser is also registered with its parent. |
573 |
> |
* phaser has a parent, and the given number of parties is greater |
574 |
> |
* than zero, and this phaser previously had no registered |
575 |
> |
* parties, this child phaser is also registered with its parent. |
576 |
> |
* If this phaser is terminated, the attempt to register has no |
577 |
> |
* effect, and a negative value is returned. |
578 |
|
* |
579 |
|
* @param parties the number of additional parties required to |
580 |
|
* advance to the next phase |
581 |
< |
* @return the arrival phase number to which this registration applied |
581 |
> |
* @return the arrival phase number to which this registration |
582 |
> |
* applied. If this value is negative, then this phaser has |
583 |
> |
* terminated, in which case registration has no effect. |
584 |
|
* @throws IllegalStateException if attempting to register more |
585 |
|
* than the maximum supported number of parties |
586 |
|
* @throws IllegalArgumentException if {@code parties < 0} |
606 |
|
* of unarrived parties would become negative |
607 |
|
*/ |
608 |
|
public int arrive() { |
609 |
< |
return doArrive(false); |
609 |
> |
return doArrive(ONE_ARRIVAL); |
610 |
|
} |
611 |
|
|
612 |
|
/** |
626 |
|
* of registered or unarrived parties would become negative |
627 |
|
*/ |
628 |
|
public int arriveAndDeregister() { |
629 |
< |
return doArrive(true); |
629 |
> |
return doArrive(ONE_DEREGISTER); |
630 |
|
} |
631 |
|
|
632 |
|
/** |
642 |
|
* IllegalStateException} only upon some subsequent operation on |
643 |
|
* this phaser, if ever. |
644 |
|
* |
645 |
< |
* @return the arrival phase number, or a negative number if terminated |
645 |
> |
* @return the arrival phase number, or the (negative) |
646 |
> |
* {@linkplain #getPhase() current phase} if terminated |
647 |
|
* @throws IllegalStateException if not terminated and the number |
648 |
|
* of unarrived parties would become negative |
649 |
|
*/ |
650 |
|
public int arriveAndAwaitAdvance() { |
651 |
< |
return awaitAdvance(doArrive(false)); |
651 |
> |
// Specialization of doArrive+awaitAdvance eliminating some reads/paths |
652 |
> |
final Phaser root = this.root; |
653 |
> |
for (;;) { |
654 |
> |
long s = (root == this) ? state : reconcileState(); |
655 |
> |
int phase = (int)(s >>> PHASE_SHIFT); |
656 |
> |
if (phase < 0) |
657 |
> |
return phase; |
658 |
> |
int counts = (int)s; |
659 |
> |
int unarrived = (counts == EMPTY) ? 0 : (counts & UNARRIVED_MASK); |
660 |
> |
if (unarrived <= 0) |
661 |
> |
throw new IllegalStateException(badArrive(s)); |
662 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, |
663 |
> |
s -= ONE_ARRIVAL)) { |
664 |
> |
if (unarrived > 1) |
665 |
> |
return root.internalAwaitAdvance(phase, null); |
666 |
> |
if (root != this) |
667 |
> |
return parent.arriveAndAwaitAdvance(); |
668 |
> |
long n = s & PARTIES_MASK; // base of next state |
669 |
> |
int nextUnarrived = (int)n >>> PARTIES_SHIFT; |
670 |
> |
if (onAdvance(phase, nextUnarrived)) |
671 |
> |
n |= TERMINATION_BIT; |
672 |
> |
else if (nextUnarrived == 0) |
673 |
> |
n |= EMPTY; |
674 |
> |
else |
675 |
> |
n |= nextUnarrived; |
676 |
> |
int nextPhase = (phase + 1) & MAX_PHASE; |
677 |
> |
n |= (long)nextPhase << PHASE_SHIFT; |
678 |
> |
if (!UNSAFE.compareAndSwapLong(this, stateOffset, s, n)) |
679 |
> |
return (int)(state >>> PHASE_SHIFT); // terminated |
680 |
> |
releaseWaiters(phase); |
681 |
> |
return nextPhase; |
682 |
> |
} |
683 |
> |
} |
684 |
|
} |
685 |
|
|
686 |
|
/** |
691 |
|
* @param phase an arrival phase number, or negative value if |
692 |
|
* terminated; this argument is normally the value returned by a |
693 |
|
* previous call to {@code arrive} or {@code arriveAndDeregister}. |
694 |
< |
* @return the next arrival phase number, or a negative value |
695 |
< |
* if terminated or argument is negative |
694 |
> |
* @return the next arrival phase number, or the argument if it is |
695 |
> |
* negative, or the (negative) {@linkplain #getPhase() current phase} |
696 |
> |
* if terminated |
697 |
|
*/ |
698 |
|
public int awaitAdvance(int phase) { |
699 |
< |
Phaser rt; |
700 |
< |
int p = (int)(state >>> PHASE_SHIFT); |
699 |
> |
final Phaser root = this.root; |
700 |
> |
long s = (root == this) ? state : reconcileState(); |
701 |
> |
int p = (int)(s >>> PHASE_SHIFT); |
702 |
|
if (phase < 0) |
703 |
|
return phase; |
704 |
< |
if (p == phase) { |
705 |
< |
if ((p = (int)((rt = root).state >>> PHASE_SHIFT)) == phase) |
646 |
< |
return rt.internalAwaitAdvance(phase, null); |
647 |
< |
reconcileState(); |
648 |
< |
} |
704 |
> |
if (p == phase) |
705 |
> |
return root.internalAwaitAdvance(phase, null); |
706 |
|
return p; |
707 |
|
} |
708 |
|
|
716 |
|
* @param phase an arrival phase number, or negative value if |
717 |
|
* terminated; this argument is normally the value returned by a |
718 |
|
* previous call to {@code arrive} or {@code arriveAndDeregister}. |
719 |
< |
* @return the next arrival phase number, or a negative value |
720 |
< |
* if terminated or argument is negative |
719 |
> |
* @return the next arrival phase number, or the argument if it is |
720 |
> |
* negative, or the (negative) {@linkplain #getPhase() current phase} |
721 |
> |
* if terminated |
722 |
|
* @throws InterruptedException if thread interrupted while waiting |
723 |
|
*/ |
724 |
|
public int awaitAdvanceInterruptibly(int phase) |
725 |
|
throws InterruptedException { |
726 |
< |
Phaser rt; |
727 |
< |
int p = (int)(state >>> PHASE_SHIFT); |
726 |
> |
final Phaser root = this.root; |
727 |
> |
long s = (root == this) ? state : reconcileState(); |
728 |
> |
int p = (int)(s >>> PHASE_SHIFT); |
729 |
|
if (phase < 0) |
730 |
|
return phase; |
731 |
|
if (p == phase) { |
732 |
< |
if ((p = (int)((rt = root).state >>> PHASE_SHIFT)) == phase) { |
733 |
< |
QNode node = new QNode(this, phase, true, false, 0L); |
734 |
< |
p = rt.internalAwaitAdvance(phase, node); |
735 |
< |
if (node.wasInterrupted) |
677 |
< |
throw new InterruptedException(); |
678 |
< |
} |
679 |
< |
else |
680 |
< |
reconcileState(); |
732 |
> |
QNode node = new QNode(this, phase, true, false, 0L); |
733 |
> |
p = root.internalAwaitAdvance(phase, node); |
734 |
> |
if (node.wasInterrupted) |
735 |
> |
throw new InterruptedException(); |
736 |
|
} |
737 |
|
return p; |
738 |
|
} |
751 |
|
* {@code unit} |
752 |
|
* @param unit a {@code TimeUnit} determining how to interpret the |
753 |
|
* {@code timeout} parameter |
754 |
< |
* @return the next arrival phase number, or a negative value |
755 |
< |
* if terminated or argument is negative |
754 |
> |
* @return the next arrival phase number, or the argument if it is |
755 |
> |
* negative, or the (negative) {@linkplain #getPhase() current phase} |
756 |
> |
* if terminated |
757 |
|
* @throws InterruptedException if thread interrupted while waiting |
758 |
|
* @throws TimeoutException if timed out while waiting |
759 |
|
*/ |
761 |
|
long timeout, TimeUnit unit) |
762 |
|
throws InterruptedException, TimeoutException { |
763 |
|
long nanos = unit.toNanos(timeout); |
764 |
< |
Phaser rt; |
765 |
< |
int p = (int)(state >>> PHASE_SHIFT); |
764 |
> |
final Phaser root = this.root; |
765 |
> |
long s = (root == this) ? state : reconcileState(); |
766 |
> |
int p = (int)(s >>> PHASE_SHIFT); |
767 |
|
if (phase < 0) |
768 |
|
return phase; |
769 |
|
if (p == phase) { |
770 |
< |
if ((p = (int)((rt = root).state >>> PHASE_SHIFT)) == phase) { |
771 |
< |
QNode node = new QNode(this, phase, true, true, nanos); |
772 |
< |
p = rt.internalAwaitAdvance(phase, node); |
773 |
< |
if (node.wasInterrupted) |
774 |
< |
throw new InterruptedException(); |
775 |
< |
else if (p == phase) |
719 |
< |
throw new TimeoutException(); |
720 |
< |
} |
721 |
< |
else |
722 |
< |
reconcileState(); |
770 |
> |
QNode node = new QNode(this, phase, true, true, nanos); |
771 |
> |
p = root.internalAwaitAdvance(phase, node); |
772 |
> |
if (node.wasInterrupted) |
773 |
> |
throw new InterruptedException(); |
774 |
> |
else if (p == phase) |
775 |
> |
throw new TimeoutException(); |
776 |
|
} |
777 |
|
return p; |
778 |
|
} |
791 |
|
final Phaser root = this.root; |
792 |
|
long s; |
793 |
|
while ((s = root.state) >= 0) { |
794 |
< |
long next = (s & ~(long)(MAX_PARTIES)) | TERMINATION_BIT; |
795 |
< |
if (UNSAFE.compareAndSwapLong(root, stateOffset, s, next)) { |
796 |
< |
releaseWaiters(0); // signal all threads |
797 |
< |
releaseWaiters(1); |
794 |
> |
if (UNSAFE.compareAndSwapLong(root, stateOffset, |
795 |
> |
s, s | TERMINATION_BIT)) { |
796 |
> |
// signal all threads |
797 |
> |
releaseWaiters(0); // Waiters on evenQ |
798 |
> |
releaseWaiters(1); // Waiters on oddQ |
799 |
|
return; |
800 |
|
} |
801 |
|
} |
825 |
|
|
826 |
|
/** |
827 |
|
* Returns the number of registered parties that have arrived at |
828 |
< |
* the current phase of this phaser. |
828 |
> |
* the current phase of this phaser. If this phaser has terminated, |
829 |
> |
* the returned value is meaningless and arbitrary. |
830 |
|
* |
831 |
|
* @return the number of arrived parties |
832 |
|
*/ |
836 |
|
|
837 |
|
/** |
838 |
|
* Returns the number of registered parties that have not yet |
839 |
< |
* arrived at the current phase of this phaser. |
839 |
> |
* arrived at the current phase of this phaser. If this phaser has |
840 |
> |
* terminated, the returned value is meaningless and arbitrary. |
841 |
|
* |
842 |
|
* @return the number of unarrived parties |
843 |
|
*/ |
947 |
|
*/ |
948 |
|
private void releaseWaiters(int phase) { |
949 |
|
QNode q; // first element of queue |
894 |
– |
int p; // its phase |
950 |
|
Thread t; // its thread |
896 |
– |
// assert phase != phaseOf(root.state); |
951 |
|
AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ; |
952 |
|
while ((q = head.get()) != null && |
953 |
|
q.phase != (int)(root.state >>> PHASE_SHIFT)) { |
959 |
|
} |
960 |
|
} |
961 |
|
|
962 |
+ |
/** |
963 |
+ |
* Variant of releaseWaiters that additionally tries to remove any |
964 |
+ |
* nodes no longer waiting for advance due to timeout or |
965 |
+ |
* interrupt. Currently, nodes are removed only if they are at |
966 |
+ |
* head of queue, which suffices to reduce memory footprint in |
967 |
+ |
* most usages. |
968 |
+ |
* |
969 |
+ |
* @return current phase on exit |
970 |
+ |
*/ |
971 |
+ |
private int abortWait(int phase) { |
972 |
+ |
AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ; |
973 |
+ |
for (;;) { |
974 |
+ |
Thread t; |
975 |
+ |
QNode q = head.get(); |
976 |
+ |
int p = (int)(root.state >>> PHASE_SHIFT); |
977 |
+ |
if (q == null || ((t = q.thread) != null && q.phase == p)) |
978 |
+ |
return p; |
979 |
+ |
if (head.compareAndSet(q, q.next) && t != null) { |
980 |
+ |
q.thread = null; |
981 |
+ |
LockSupport.unpark(t); |
982 |
+ |
} |
983 |
+ |
} |
984 |
+ |
} |
985 |
+ |
|
986 |
|
/** The number of CPUs, for spin control */ |
987 |
|
private static final int NCPU = Runtime.getRuntime().availableProcessors(); |
988 |
|
|
1001 |
|
|
1002 |
|
/** |
1003 |
|
* Possibly blocks and waits for phase to advance unless aborted. |
1004 |
< |
* Call only from root node. |
1004 |
> |
* Call only on root phaser. |
1005 |
|
* |
1006 |
|
* @param phase current phase |
1007 |
|
* @param node if non-null, the wait node to track interrupt and timeout; |
1009 |
|
* @return current phase |
1010 |
|
*/ |
1011 |
|
private int internalAwaitAdvance(int phase, QNode node) { |
1012 |
+ |
// assert root == this; |
1013 |
|
releaseWaiters(phase-1); // ensure old queue clean |
1014 |
|
boolean queued = false; // true when node is enqueued |
1015 |
|
int lastUnarrived = 0; // to increase spins upon change |
1052 |
|
if (node.wasInterrupted && !node.interruptible) |
1053 |
|
Thread.currentThread().interrupt(); |
1054 |
|
if (p == phase && (p = (int)(state >>> PHASE_SHIFT)) == phase) |
1055 |
< |
return p; // recheck abort |
1055 |
> |
return abortWait(phase); // possibly clean up on abort |
1056 |
|
} |
1057 |
|
releaseWaiters(phase); |
1058 |
|
return p; |
1123 |
|
|
1124 |
|
// Unsafe mechanics |
1125 |
|
|
1126 |
< |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1127 |
< |
private static final long stateOffset = |
1128 |
< |
objectFieldOffset("state", Phaser.class); |
1050 |
< |
|
1051 |
< |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1126 |
> |
private static final sun.misc.Unsafe UNSAFE; |
1127 |
> |
private static final long stateOffset; |
1128 |
> |
static { |
1129 |
|
try { |
1130 |
< |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1131 |
< |
} catch (NoSuchFieldException e) { |
1132 |
< |
// Convert Exception to corresponding Error |
1133 |
< |
NoSuchFieldError error = new NoSuchFieldError(field); |
1134 |
< |
error.initCause(e); |
1135 |
< |
throw error; |
1130 |
> |
UNSAFE = getUnsafe(); |
1131 |
> |
Class<?> k = Phaser.class; |
1132 |
> |
stateOffset = UNSAFE.objectFieldOffset |
1133 |
> |
(k.getDeclaredField("state")); |
1134 |
> |
} catch (Exception e) { |
1135 |
> |
throw new Error(e); |
1136 |
|
} |
1137 |
|
} |
1138 |
|
|