28 |
|
* start other subtasks. As indicated by the name of this class, |
29 |
|
* many programs using {@code ForkJoinTask} employ only methods |
30 |
|
* {@link #fork} and {@link #join}, or derivatives such as {@link |
31 |
< |
* #invokeAll}. However, this class also provides a number of other |
32 |
< |
* methods that can come into play in advanced usages, as well as |
33 |
< |
* extension mechanics that allow support of new forms of fork/join |
34 |
< |
* processing. |
31 |
> |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
32 |
> |
* provides a number of other methods that can come into play in |
33 |
> |
* advanced usages, as well as extension mechanics that allow |
34 |
> |
* support of new forms of fork/join processing. |
35 |
|
* |
36 |
|
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
37 |
|
* The efficiency of {@code ForkJoinTask}s stems from a set of |
153 |
|
* single int to minimize footprint and to ensure atomicity (via |
154 |
|
* CAS). Status is initially zero, and takes on nonnegative |
155 |
|
* values until completed, upon which status holds value |
156 |
< |
* NORMAL. CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
156 |
> |
* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
157 |
|
* waits by other threads have the SIGNAL bit set. Completion of |
158 |
|
* a stolen task with SIGNAL set awakens any waiters via |
159 |
|
* notifyAll. Even though suboptimal for some purposes, we use |
206 |
|
|
207 |
|
/** |
208 |
|
* Records exception and sets exceptional completion. |
209 |
< |
* |
209 |
> |
* |
210 |
|
* @return status on exit |
211 |
|
*/ |
212 |
|
private void setExceptionalCompletion(Throwable rex) { |
223 |
|
int s; // the odd construction reduces lock bias effects |
224 |
|
while ((s = status) >= 0) { |
225 |
|
try { |
226 |
< |
synchronized(this) { |
226 |
> |
synchronized (this) { |
227 |
|
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
228 |
|
wait(); |
229 |
|
} |
243 |
|
int s; |
244 |
|
if ((s = status) >= 0) { |
245 |
|
try { |
246 |
< |
synchronized(this) { |
246 |
> |
synchronized (this) { |
247 |
|
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
248 |
|
wait(millis, 0); |
249 |
|
} |
261 |
|
private void externalAwaitDone() { |
262 |
|
int s; |
263 |
|
while ((s = status) >= 0) { |
264 |
< |
synchronized(this) { |
264 |
> |
synchronized (this) { |
265 |
|
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){ |
266 |
|
boolean interrupted = false; |
267 |
|
while (status >= 0) { |
621 |
|
|
622 |
|
/** |
623 |
|
* Completes this task, and if not already aborted or cancelled, |
624 |
< |
* returning a {@code null} result upon {@code join} and related |
625 |
< |
* operations. This method may be used to provide results for |
626 |
< |
* asynchronous tasks, or to provide alternative handling for |
627 |
< |
* tasks that would not otherwise complete normally. Its use in |
628 |
< |
* other situations is discouraged. This method is |
629 |
< |
* overridable, but overridden versions must invoke {@code super} |
630 |
< |
* implementation to maintain guarantees. |
624 |
> |
* returning the given value as the result of subsequent |
625 |
> |
* invocations of {@code join} and related operations. This method |
626 |
> |
* may be used to provide results for asynchronous tasks, or to |
627 |
> |
* provide alternative handling for tasks that would not otherwise |
628 |
> |
* complete normally. Its use in other situations is |
629 |
> |
* discouraged. This method is overridable, but overridden |
630 |
> |
* versions must invoke {@code super} implementation to maintain |
631 |
> |
* guarantees. |
632 |
|
* |
633 |
|
* @param value the result value for this task |
634 |
|
*/ |
642 |
|
setCompletion(NORMAL); |
643 |
|
} |
644 |
|
|
645 |
+ |
/** |
646 |
+ |
* @throws CancellationException {@inheritDoc} |
647 |
+ |
*/ |
648 |
|
public final V get() throws InterruptedException, ExecutionException { |
649 |
< |
quietlyJoin(); |
650 |
< |
if (Thread.interrupted()) |
651 |
< |
throw new InterruptedException(); |
652 |
< |
int s = status; |
649 |
> |
int s; |
650 |
> |
if (Thread.currentThread() instanceof ForkJoinWorkerThread) { |
651 |
> |
quietlyJoin(); |
652 |
> |
s = status; |
653 |
> |
} |
654 |
> |
else { |
655 |
> |
while ((s = status) >= 0) { |
656 |
> |
synchronized (this) { // interruptible form of awaitDone |
657 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, |
658 |
> |
s, SIGNAL)) { |
659 |
> |
while (status >= 0) |
660 |
> |
wait(); |
661 |
> |
} |
662 |
> |
} |
663 |
> |
} |
664 |
> |
} |
665 |
|
if (s < NORMAL) { |
666 |
|
Throwable ex; |
667 |
|
if (s == CANCELLED) |
672 |
|
return getRawResult(); |
673 |
|
} |
674 |
|
|
675 |
+ |
/** |
676 |
+ |
* @throws CancellationException {@inheritDoc} |
677 |
+ |
*/ |
678 |
|
public final V get(long timeout, TimeUnit unit) |
679 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
680 |
|
Thread t = Thread.currentThread(); |
698 |
|
boolean dec = false; // true if pool count decremented |
699 |
|
long nanos = unit.toNanos(timeout); |
700 |
|
for (;;) { |
701 |
< |
if (Thread.interrupted() && pool == null) { |
701 |
> |
if (pool == null && Thread.interrupted()) { |
702 |
|
interrupted = true; |
703 |
|
break; |
704 |
|
} |
716 |
|
long ms = nt / 1000000; |
717 |
|
int ns = (int) (nt % 1000000); |
718 |
|
try { |
719 |
< |
synchronized(this) { |
719 |
> |
synchronized (this) { |
720 |
|
if (status >= 0) |
721 |
|
wait(ms, ns); |
722 |
|
} |
783 |
|
/** |
784 |
|
* Commences performing this task and awaits its completion if |
785 |
|
* necessary, without returning its result or throwing its |
786 |
< |
* exception. This method may be useful when processing |
768 |
< |
* collections of tasks when some have been cancelled or otherwise |
769 |
< |
* known to have aborted. |
786 |
> |
* exception. |
787 |
|
*/ |
788 |
|
public final void quietlyInvoke() { |
789 |
|
if (status >= 0) { |