| 17 |
|
* {@link java.util.concurrent.CountDownLatch CountDownLatch} |
| 18 |
|
* but supporting more flexible usage. |
| 19 |
|
* |
| 20 |
< |
* <p> <b>Registration.</b> Unlike the case for other barriers, the |
| 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 |
| 30 |
|
* (However, you can introduce such bookkeeping by subclassing this |
| 31 |
|
* class.) |
| 32 |
|
* |
| 33 |
< |
* <p> <b>Synchronization.</b> Like a {@code CyclicBarrier}, a {@code |
| 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 |
| 74 |
|
* |
| 75 |
|
* </ul> |
| 76 |
|
* |
| 77 |
< |
* <p> <b>Termination.</b> A phaser may enter a <em>termination</em> |
| 77 |
> |
* <p><b>Termination.</b> A phaser may enter a <em>termination</em> |
| 78 |
|
* state, that may be checked using method {@link #isTerminated}. Upon |
| 79 |
|
* termination, all synchronization methods immediately return without |
| 80 |
|
* waiting for advance, as indicated by a negative return value. |
| 89 |
|
* also available to abruptly release waiting threads and allow them |
| 90 |
|
* to terminate. |
| 91 |
|
* |
| 92 |
< |
* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., |
| 92 |
> |
* <p><b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., |
| 93 |
|
* constructed in tree structures) to reduce contention. Phasers with |
| 94 |
|
* large numbers of parties that would otherwise experience heavy |
| 95 |
|
* synchronization contention costs may instead be set up so that |
| 271 |
|
private static final int PHASE_SHIFT = 32; |
| 272 |
|
private static final int UNARRIVED_MASK = 0xffff; // to mask ints |
| 273 |
|
private static final long PARTIES_MASK = 0xffff0000L; // to mask longs |
| 274 |
+ |
private static final long COUNTS_MASK = 0xffffffffL; |
| 275 |
|
private static final long TERMINATION_BIT = 1L << 63; |
| 276 |
|
|
| 277 |
|
// some special values |
| 454 |
|
* subphasers have not yet done so, in which case they must finish |
| 455 |
|
* their own advance by setting unarrived to parties (or if |
| 456 |
|
* 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. |
| 457 |
|
* |
| 458 |
|
* @return reconciled state |
| 459 |
|
*/ |
| 461 |
|
final Phaser root = this.root; |
| 462 |
|
long s = state; |
| 463 |
|
if (root != this) { |
| 464 |
< |
int phase, u, p; |
| 465 |
< |
// CAS root phase with current parties; possibly trip unarrived |
| 464 |
> |
int phase, p; |
| 465 |
> |
// CAS to root phase with current parties, tripping unarrived |
| 466 |
|
while ((phase = (int)(root.state >>> PHASE_SHIFT)) != |
| 467 |
|
(int)(s >>> PHASE_SHIFT) && |
| 468 |
|
!UNSAFE.compareAndSwapLong |
| 469 |
|
(this, stateOffset, s, |
| 470 |
|
s = (((long)phase << PHASE_SHIFT) | |
| 471 |
< |
(s & PARTIES_MASK) | |
| 472 |
< |
((p = (int)s >>> PARTIES_SHIFT) == 0 ? EMPTY : |
| 473 |
< |
((u = (int)s & UNARRIVED_MASK) == 0 && phase >= 0) ? |
| 477 |
< |
p : u)))) |
| 471 |
> |
((phase < 0) ? (s & COUNTS_MASK) : |
| 472 |
> |
(((p = (int)s >>> PARTIES_SHIFT) == 0) ? EMPTY : |
| 473 |
> |
((s & PARTIES_MASK) | p)))))) |
| 474 |
|
s = state; |
| 475 |
|
} |
| 476 |
|
return s; |
