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root/jsr166/jsr166/src/jsr166y/ForkJoinTask.java

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.33 by dl, Tue Aug 4 00:36:45 2009 UTC vs.
Revision 1.38 by dl, Tue Aug 4 22:47:08 2009 UTC

#	Line 68 | Line 68 | import java.util.WeakHashMap;
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
#	Line 111 | Line 125 | import java.util.WeakHashMap;
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
#	Line 378 | Line 392 | public abstract class ForkJoinTask<V> im
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;
#	Line 389 | Line 406 | public abstract class ForkJoinTask<V> im
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		}
#	Line 401 | Line 416 | public abstract class ForkJoinTask<V> im
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
#	Line 529 | Line 545 | public abstract class ForkJoinTask<V> im
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() {
#	Line 543 | Line 558 | public abstract class ForkJoinTask<V> im
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 more than one task
564	>	* encounters an exception, then this method throws any one of
565	>	* these exceptions.  The individual status of each task may be
566	>	* checked using {@link #getException()} and related methods.
567		*
568		* <p>This method may be invoked only from within {@code
569		* ForkJoinTask} computations (as may be determined using method
#	Line 555 | Line 574 | public abstract class ForkJoinTask<V> im
574		* @param t1 the first task
575		* @param t2 the second task
576		* @throws NullPointerException if any task is null
558	–	* @throws RuntimeException or Error if a task did so
577		*/
578		public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
579		t2.fork();
#	Line 565 | Line 583 | public abstract class ForkJoinTask<V> im
583
584		/**
585		* Forks the given tasks, returning when {@code isDone} holds for
586	<	* each task or an exception is encountered. If any task
587	<	* encounters an exception, others may be, but are not guaranteed
588	<	* to be, cancelled.
586	>	* each task or an (unchecked) exception is encountered, in which
587	>	* case the exception is rethrown. If any task encounters an
588	>	* exception, others may be, but are not guaranteed to be,
589	>	* cancelled.  If more than one task encounters an exception, then
590	>	* this method throws any one of these exceptions.  The individual
591	>	* status of each task may be checked using {@link #getException()}
592	>	* and related methods.
593		*
594		* <p>This method may be invoked only from within {@code
595		* ForkJoinTask} computations (as may be determined using method
#	Line 576 | Line 598 | public abstract class ForkJoinTask<V> im
598		* ClassCastException}.
599		*
600		* @param tasks the tasks
601	<	* @throws NullPointerException if tasks or any element are null
580	<	* @throws RuntimeException or Error if any task did so
601	>	* @throws NullPointerException if any task is null
602		*/
603		public static void invokeAll(ForkJoinTask<?>... tasks) {
604		Throwable ex = null;
#	Line 614 | Line 635 | public abstract class ForkJoinTask<V> im
635
636		/**
637		* Forks all tasks in the specified collection, returning when
638	<	* {@code isDone} holds for each task or an exception is
639	<	* encountered.  If any task encounters an exception, others may
640	<	* be, but are not guaranteed to be, cancelled. The behavior of
641	<	* this operation is undefined if the specified collection is
642	<	* modified while the operation is in progress.
638	>	* {@code isDone} holds for each task or an (unchecked) exception
639	>	* is encountered.  If any task encounters an exception, others
640	>	* may be, but are not guaranteed to be, cancelled.  If more than
641	>	* one task encounters an exception, then this method throws any
642	>	* one of these exceptions.  The individual status of each task
643	>	* may be checked using {@link #getException()} and related
644	>	* methods.  The behavior of this operation is undefined if the
645	>	* specified collection is modified while the operation is in
646	>	* progress.
647		*
648		* <p>This method may be invoked only from within {@code
649		* ForkJoinTask} computations (as may be determined using method
#	Line 629 | Line 654 | public abstract class ForkJoinTask<V> im
654		* @param tasks the collection of tasks
655		* @return the tasks argument, to simplify usage
656		* @throws NullPointerException if tasks or any element are null
632	–	* @throws RuntimeException or Error if any task did so
657		*/
658		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
659		if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
#	Line 673 | Line 697 | public abstract class ForkJoinTask<V> im
697		}
698
699		/**
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	–	/**
700		* Attempts to cancel execution of this task. This attempt will
701		* fail if the task has already completed, has already been
702		* cancelled, or could not be cancelled for some other reason. If
#	Line 721 | Line 726 | public abstract class ForkJoinTask<V> im
726		}
727
728		/**
729	+	* Returns {@code true} if the computation performed by this task
730	+	* has completed (or has been cancelled).
731	+	*
732	+	* @return {@code true} if this computation has completed
733	+	*/
734	+	public final boolean isDone() {
735	+	return status < 0;
736	+	}
737	+
738	+	/**
739	+	* Returns {@code true} if this task was cancelled.
740	+	*
741	+	* @return {@code true} if this task was cancelled
742	+	*/
743	+	public final boolean isCancelled() {
744	+	return (status & COMPLETION_MASK) == CANCELLED;
745	+	}
746	+
747	+	/**
748		* Returns {@code true} if this task threw an exception or was cancelled.
749		*
750		* @return {@code true} if this task threw an exception or was cancelled
#	Line 730 | Line 754 | public abstract class ForkJoinTask<V> im
754		}
755
756		/**
757	+	* Returns {@code true} if this task completed without throwing an
758	+	* exception and was not cancelled.
759	+	*
760	+	* @return {@code true} if this task completed without throwing an
761	+	* exception and was not cancelled
762	+	*/
763	+	public final boolean isCompletedNormally() {
764	+	return (status & COMPLETION_MASK) == NORMAL;
765	+	}
766	+
767	+	/**
768	+	* Returns {@code true} if this task threw an exception.
769	+	*
770	+	* @return {@code true} if this task threw an exception
771	+	*/
772	+	public final boolean isCompletedExceptionally() {
773	+	return (status & COMPLETION_MASK) == EXCEPTIONAL;
774	+	}
775	+
776	+	/**
777		* Returns the exception thrown by the base computation, or a
778		* {@code CancellationException} if cancelled, or {@code null} if
779		* none or if the method has not yet completed.
#	Line 738 | Line 782 | public abstract class ForkJoinTask<V> im
782		*/
783		public final Throwable getException() {
784		int s = status & COMPLETION_MASK;
785	<	if (s >= NORMAL)
786	<	return null;
787	<	if (s == CANCELLED)
744	<	return new CancellationException();
745	<	return exceptionMap.get(this);
785	>	return ((s >= NORMAL)    ? null :
786	>	(s == CANCELLED) ? new CancellationException() :
787	>	exceptionMap.get(this));
788		}
789
790		/**
#	Line 1022 | Line 1064 | public abstract class ForkJoinTask<V> im
1064		* called otherwise. The return value controls whether this task
1065		* is considered to be done normally. It may return false in
1066		* asynchronous actions that require explicit invocations of
1067	<	* {@link #complete} to become joinable. It may throw exceptions
1068	<	* to indicate abnormal exit.
1067	>	* {@link #complete} to become joinable. It may also throw an
1068	>	* (unchecked) exception to indicate abnormal exit.
1069		*
1070		* @return {@code true} if completed normally
1029	–	* @throws Error or RuntimeException if encountered during computation
1071		*/
1072		protected abstract boolean exec();
1073

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