68 |
|
* execute other tasks while awaiting joins, which is sometimes more |
69 |
|
* efficient but only applies when all subtasks are known to be |
70 |
|
* strictly tree-structured. Method {@link #invoke} is semantically |
71 |
< |
* equivalent to {@code fork(); join()} but always attempts to |
72 |
< |
* begin execution in the current thread. The "<em>quiet</em>" forms |
73 |
< |
* of these methods do not extract results or report exceptions. These |
71 |
> |
* equivalent to {@code fork(); join()} but always attempts to begin |
72 |
> |
* execution in the current thread. The "<em>quiet</em>" forms of |
73 |
> |
* these methods do not extract results or report exceptions. These |
74 |
|
* may be useful when a set of tasks are being executed, and you need |
75 |
|
* to delay processing of results or exceptions until all complete. |
76 |
|
* Method {@code invokeAll} (available in multiple versions) |
77 |
|
* performs the most common form of parallel invocation: forking a set |
78 |
|
* of tasks and joining them all. |
79 |
|
* |
80 |
+ |
* <p>The execution status of tasks may be queried at several levels |
81 |
+ |
* of detail: {@link #isDone} is true if a task completed in any way |
82 |
+ |
* (including the case where a task was cancelled without executing); |
83 |
+ |
* {@link #isCancelled} is true if completion was due to cancellation; |
84 |
+ |
* {@link #isCompletedNormally} is true if a task completed without |
85 |
+ |
* cancellation or encountering an exception; {@link |
86 |
+ |
* #isCompletedExceptionally} is true if if the task encountered an |
87 |
+ |
* exception (in which case {@link #getException} returns the |
88 |
+ |
* exception); {@link #isCancelled} is true if the task was cancelled |
89 |
+ |
* (in which case {@link #getException} returns a {@link |
90 |
+ |
* java.util.concurrent.CancellationException}); and {@link |
91 |
+ |
* #isCompletedAbnormally} is true if a task was either cancelled or |
92 |
+ |
* encountered an exception. |
93 |
+ |
* |
94 |
|
* <p>The ForkJoinTask class is not usually directly subclassed. |
95 |
|
* Instead, you subclass one of the abstract classes that support a |
96 |
|
* particular style of fork/join processing, typically {@link |
125 |
|
* improve throughput. If too small, then memory and internal task |
126 |
|
* maintenance overhead may overwhelm processing. |
127 |
|
* |
128 |
< |
* <p>This class provides {@code adapt} methods for {@link |
129 |
< |
* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that |
130 |
< |
* may be of use when mixing execution of ForkJoinTasks with other |
131 |
< |
* kinds of tasks. When all tasks are of this form, consider using a |
132 |
< |
* pool in {@link ForkJoinPool#setAsyncMode}. |
128 |
> |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
129 |
> |
* and {@link Callable}, that may be of use when mixing execution of |
130 |
> |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks |
131 |
> |
* are of this form, consider using a pool in |
132 |
> |
* {@linkplain ForkJoinPool#setAsyncMode async mode}. |
133 |
|
* |
134 |
|
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
135 |
|
* used in extensions such as remote execution frameworks. It is |
392 |
|
|
393 |
|
/** |
394 |
|
* Returns result or throws exception using j.u.c.Future conventions. |
395 |
< |
* Only call when {@code isDone} known to be true. |
395 |
> |
* Only call when {@code isDone} known to be true or thread known |
396 |
> |
* to be interrupted. |
397 |
|
*/ |
398 |
|
private V reportFutureResult() |
399 |
< |
throws ExecutionException, InterruptedException { |
399 |
> |
throws InterruptedException, ExecutionException { |
400 |
> |
if (Thread.interrupted()) |
401 |
> |
throw new InterruptedException(); |
402 |
|
int s = status & COMPLETION_MASK; |
403 |
|
if (s < NORMAL) { |
404 |
|
Throwable ex; |
406 |
|
throw new CancellationException(); |
407 |
|
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
408 |
|
throw new ExecutionException(ex); |
392 |
– |
if (Thread.interrupted()) |
393 |
– |
throw new InterruptedException(); |
409 |
|
} |
410 |
|
return getRawResult(); |
411 |
|
} |
416 |
|
*/ |
417 |
|
private V reportTimedFutureResult() |
418 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
419 |
+ |
if (Thread.interrupted()) |
420 |
+ |
throw new InterruptedException(); |
421 |
|
Throwable ex; |
422 |
|
int s = status & COMPLETION_MASK; |
423 |
|
if (s == NORMAL) |
424 |
|
return getRawResult(); |
425 |
< |
if (s == CANCELLED) |
425 |
> |
else if (s == CANCELLED) |
426 |
|
throw new CancellationException(); |
427 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
427 |
> |
else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
428 |
|
throw new ExecutionException(ex); |
429 |
< |
if (Thread.interrupted()) |
430 |
< |
throw new InterruptedException(); |
414 |
< |
throw new TimeoutException(); |
429 |
> |
else |
430 |
> |
throw new TimeoutException(); |
431 |
|
} |
432 |
|
|
433 |
|
// internal execution methods |
545 |
|
|
546 |
|
/** |
547 |
|
* Commences performing this task, awaits its completion if |
548 |
< |
* necessary, and return its result. |
548 |
> |
* necessary, and return its result, or throws an (unchecked) |
549 |
> |
* exception if the underlying computation did so. |
550 |
|
* |
534 |
– |
* @throws Throwable (a RuntimeException, Error, or unchecked |
535 |
– |
* exception) if the underlying computation did so |
551 |
|
* @return the computed result |
552 |
|
*/ |
553 |
|
public final V invoke() { |
558 |
|
} |
559 |
|
|
560 |
|
/** |
561 |
< |
* Forks the given tasks, returning when {@code isDone} holds |
562 |
< |
* for each task or an exception is encountered. |
561 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
562 |
> |
* each task or an (unchecked) exception is encountered, in which |
563 |
> |
* case the exception is rethrown. If either task encounters an |
564 |
> |
* exception, the other one may be, but is not guaranteed to be, |
565 |
> |
* cancelled. If both tasks throw an exception, then this method |
566 |
> |
* throws one of them. The individual status of each task may be |
567 |
> |
* checked using {@link #getException()} and related methods. |
568 |
|
* |
569 |
|
* <p>This method may be invoked only from within {@code |
570 |
|
* ForkJoinTask} computations (as may be determined using method |
575 |
|
* @param t1 the first task |
576 |
|
* @param t2 the second task |
577 |
|
* @throws NullPointerException if any task is null |
558 |
– |
* @throws RuntimeException or Error if a task did so |
578 |
|
*/ |
579 |
|
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
580 |
|
t2.fork(); |
584 |
|
|
585 |
|
/** |
586 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
587 |
< |
* each task or an exception is encountered. If any task |
588 |
< |
* encounters an exception, others may be, but are not guaranteed |
589 |
< |
* to be, cancelled. |
587 |
> |
* each task or an (unchecked) exception is encountered, in which |
588 |
> |
* case the exception is rethrown. If any task encounters an |
589 |
> |
* exception, others may be, but are not guaranteed to be, |
590 |
> |
* cancelled. If more than one task encounters an exception, then |
591 |
> |
* this method throws any one of these exceptions. The individual |
592 |
> |
* status of each task may be checked using {@link #getException()} |
593 |
> |
* and related methods. |
594 |
|
* |
595 |
|
* <p>This method may be invoked only from within {@code |
596 |
|
* ForkJoinTask} computations (as may be determined using method |
599 |
|
* ClassCastException}. |
600 |
|
* |
601 |
|
* @param tasks the tasks |
602 |
< |
* @throws NullPointerException if tasks or any element are null |
580 |
< |
* @throws RuntimeException or Error if any task did so |
602 |
> |
* @throws NullPointerException if any task is null |
603 |
|
*/ |
604 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
605 |
|
Throwable ex = null; |
636 |
|
|
637 |
|
/** |
638 |
|
* Forks all tasks in the specified collection, returning when |
639 |
< |
* {@code isDone} holds for each task or an exception is |
640 |
< |
* encountered. If any task encounters an exception, others may |
641 |
< |
* be, but are not guaranteed to be, cancelled. The behavior of |
642 |
< |
* this operation is undefined if the specified collection is |
643 |
< |
* modified while the operation is in progress. |
639 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
640 |
> |
* is encountered. If any task encounters an exception, others |
641 |
> |
* may be, but are not guaranteed to be, cancelled. If more than |
642 |
> |
* one task encounters an exception, then this method throws any |
643 |
> |
* one of these exceptions. The individual status of each task |
644 |
> |
* may be checked using {@link #getException()} and related |
645 |
> |
* methods. The behavior of this operation is undefined if the |
646 |
> |
* specified collection is modified while the operation is in |
647 |
> |
* progress. |
648 |
|
* |
649 |
|
* <p>This method may be invoked only from within {@code |
650 |
|
* ForkJoinTask} computations (as may be determined using method |
655 |
|
* @param tasks the collection of tasks |
656 |
|
* @return the tasks argument, to simplify usage |
657 |
|
* @throws NullPointerException if tasks or any element are null |
632 |
– |
* @throws RuntimeException or Error if any task did so |
658 |
|
*/ |
659 |
|
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
660 |
|
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
698 |
|
} |
699 |
|
|
700 |
|
/** |
676 |
– |
* Returns {@code true} if the computation performed by this task |
677 |
– |
* has completed (or has been cancelled). |
678 |
– |
* |
679 |
– |
* @return {@code true} if this computation has completed |
680 |
– |
*/ |
681 |
– |
public final boolean isDone() { |
682 |
– |
return status < 0; |
683 |
– |
} |
684 |
– |
|
685 |
– |
/** |
686 |
– |
* Returns {@code true} if this task was cancelled. |
687 |
– |
* |
688 |
– |
* @return {@code true} if this task was cancelled |
689 |
– |
*/ |
690 |
– |
public final boolean isCancelled() { |
691 |
– |
return (status & COMPLETION_MASK) == CANCELLED; |
692 |
– |
} |
693 |
– |
|
694 |
– |
/** |
701 |
|
* Attempts to cancel execution of this task. This attempt will |
702 |
|
* fail if the task has already completed, has already been |
703 |
|
* cancelled, or could not be cancelled for some other reason. If |
726 |
|
return (status & COMPLETION_MASK) == CANCELLED; |
727 |
|
} |
728 |
|
|
729 |
+ |
public final boolean isDone() { |
730 |
+ |
return status < 0; |
731 |
+ |
} |
732 |
+ |
|
733 |
+ |
public final boolean isCancelled() { |
734 |
+ |
return (status & COMPLETION_MASK) == CANCELLED; |
735 |
+ |
} |
736 |
+ |
|
737 |
|
/** |
738 |
|
* Returns {@code true} if this task threw an exception or was cancelled. |
739 |
|
* |
744 |
|
} |
745 |
|
|
746 |
|
/** |
747 |
+ |
* Returns {@code true} if this task completed without throwing an |
748 |
+ |
* exception and was not cancelled. |
749 |
+ |
* |
750 |
+ |
* @return {@code true} if this task completed without throwing an |
751 |
+ |
* exception and was not cancelled |
752 |
+ |
*/ |
753 |
+ |
public final boolean isCompletedNormally() { |
754 |
+ |
return (status & COMPLETION_MASK) == NORMAL; |
755 |
+ |
} |
756 |
+ |
|
757 |
+ |
/** |
758 |
+ |
* Returns {@code true} if this task threw an exception. |
759 |
+ |
* |
760 |
+ |
* @return {@code true} if this task threw an exception |
761 |
+ |
*/ |
762 |
+ |
public final boolean isCompletedExceptionally() { |
763 |
+ |
return (status & COMPLETION_MASK) == EXCEPTIONAL; |
764 |
+ |
} |
765 |
+ |
|
766 |
+ |
/** |
767 |
|
* Returns the exception thrown by the base computation, or a |
768 |
|
* {@code CancellationException} if cancelled, or {@code null} if |
769 |
|
* none or if the method has not yet completed. |
772 |
|
*/ |
773 |
|
public final Throwable getException() { |
774 |
|
int s = status & COMPLETION_MASK; |
775 |
< |
if (s >= NORMAL) |
776 |
< |
return null; |
777 |
< |
if (s == CANCELLED) |
744 |
< |
return new CancellationException(); |
745 |
< |
return exceptionMap.get(this); |
775 |
> |
return ((s >= NORMAL) ? null : |
776 |
> |
(s == CANCELLED) ? new CancellationException() : |
777 |
> |
exceptionMap.get(this)); |
778 |
|
} |
779 |
|
|
780 |
|
/** |
1054 |
|
* called otherwise. The return value controls whether this task |
1055 |
|
* is considered to be done normally. It may return false in |
1056 |
|
* asynchronous actions that require explicit invocations of |
1057 |
< |
* {@link #complete} to become joinable. It may throw exceptions |
1058 |
< |
* to indicate abnormal exit. |
1057 |
> |
* {@link #complete} to become joinable. It may also throw an |
1058 |
> |
* (unchecked) exception to indicate abnormal exit. |
1059 |
|
* |
1060 |
|
* @return {@code true} if completed normally |
1029 |
– |
* @throws Error or RuntimeException if encountered during computation |
1061 |
|
*/ |
1062 |
|
protected abstract boolean exec(); |
1063 |
|
|