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root/jsr166/jsr166/src/main/java/util/concurrent/ForkJoinTask.java

Comparing jsr166/src/main/java/util/concurrent/ForkJoinTask.java (file contents):
Revision 1.7 by jsr166, Tue Aug 4 01:23:41 2009 UTC vs.
Revision 1.8 by jsr166, Tue Aug 4 20:41:40 2009 UTC

#	Line 66 | Line 66 | import java.util.WeakHashMap;
66		* execute other tasks while awaiting joins, which is sometimes more
67		* efficient but only applies when all subtasks are known to be
68		* strictly tree-structured. Method {@link #invoke} is semantically
69	<	* equivalent to {@code fork(); join()} but always attempts to
70	<	* begin execution in the current thread. The "<em>quiet</em>" forms
71	<	* of these methods do not extract results or report exceptions. These
69	>	* equivalent to {@code fork(); join()} but always attempts to begin
70	>	* execution in the current thread. The "<em>quiet</em>" forms of
71	>	* these methods do not extract results or report exceptions. These
72		* may be useful when a set of tasks are being executed, and you need
73		* to delay processing of results or exceptions until all complete.
74		* Method {@code invokeAll} (available in multiple versions)
75		* performs the most common form of parallel invocation: forking a set
76		* of tasks and joining them all.
77		*
78	+	* <p>The execution status of tasks may be queried at several levels
79	+	* of detail: {@link #isDone} is true if a task completed in any way
80	+	* (including the case where a task was cancelled without executing);
81	+	* {@link #isCancelled} is true if completion was due to cancellation;
82	+	* {@link #isCompletedNormally} is true if a task completed without
83	+	* cancellation or encountering an exception; {@link
84	+	* #isCompletedExceptionally} is true if if the task encountered an
85	+	* exception (in which case {@link #getException} returns the
86	+	* exception); {@link #isCancelled} is true if the task was cancelled
87	+	* (in which case {@link #getException} returns a {@link
88	+	* java.util.concurrent.CancellationException}); and {@link
89	+	* #isCompletedAbnormally} is true if a task was either cancelled or
90	+	* encountered an exception.
91	+	*
92		* <p>The ForkJoinTask class is not usually directly subclassed.
93		* Instead, you subclass one of the abstract classes that support a
94		* particular style of fork/join processing, typically {@link
#	Line 109 | Line 123 | import java.util.WeakHashMap;
123		* improve throughput. If too small, then memory and internal task
124		* maintenance overhead may overwhelm processing.
125		*
126	<	* <p>This class provides {@code adapt} methods for {@link
127	<	* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that
128	<	* may be of use when mixing execution of ForkJoinTasks with other
129	<	* kinds of tasks. When all tasks are of this form, consider using a
130	<	* pool in {@link ForkJoinPool#setAsyncMode}.
126	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
127	>	* and {@link Callable}, that may be of use when mixing execution of
128	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
129	>	* are of this form, consider using a pool in
130	>	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
131		*
132		* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
133		* used in extensions such as remote execution frameworks. It is
#	Line 379 | Line 393 | public abstract class ForkJoinTask<V> im
393		* Only call when {@code isDone} known to be true.
394		*/
395		private V reportFutureResult()
396	<	throws ExecutionException, InterruptedException {
396	>	throws InterruptedException, ExecutionException {
397	>	if (Thread.interrupted())
398	>	throw new InterruptedException();
399		int s = status & COMPLETION_MASK;
400		if (s < NORMAL) {
401		Throwable ex;
#	Line 387 | Line 403 | public abstract class ForkJoinTask<V> im
403		throw new CancellationException();
404		if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
405		throw new ExecutionException(ex);
390	–	if (Thread.interrupted())
391	–	throw new InterruptedException();
406		}
407		return getRawResult();
408		}
#	Line 399 | Line 413 | public abstract class ForkJoinTask<V> im
413		*/
414		private V reportTimedFutureResult()
415		throws InterruptedException, ExecutionException, TimeoutException {
416	+	if (Thread.interrupted())
417	+	throw new InterruptedException();
418		Throwable ex;
419		int s = status & COMPLETION_MASK;
420		if (s == NORMAL)
421		return getRawResult();
422	<	if (s == CANCELLED)
422	>	else if (s == CANCELLED)
423		throw new CancellationException();
424	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
424	>	else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
425		throw new ExecutionException(ex);
426	<	if (Thread.interrupted())
427	<	throw new InterruptedException();
412	<	throw new TimeoutException();
426	>	else
427	>	throw new TimeoutException();
428		}
429
430		// internal execution methods
#	Line 527 | Line 542 | public abstract class ForkJoinTask<V> im
542
543		/**
544		* Commences performing this task, awaits its completion if
545	<	* necessary, and return its result.
545	>	* necessary, and return its result, or throws an (unchecked)
546	>	* exception if the underlying computation did so.
547		*
532	–	* @throws Throwable (a RuntimeException, Error, or unchecked
533	–	* exception) if the underlying computation did so
548		* @return the computed result
549		*/
550		public final V invoke() {
#	Line 541 | Line 555 | public abstract class ForkJoinTask<V> im
555		}
556
557		/**
558	<	* Forks the given tasks, returning when {@code isDone} holds
559	<	* for each task or an exception is encountered.
558	>	* Forks the given tasks, returning when {@code isDone} holds for
559	>	* each task or an (unchecked) exception is encountered, in which
560	>	* case the exception is rethrown.  If more than one task
561	>	* encounters an exception, then this method throws any one of
562	>	* these exceptions.  The individual status of each task may be
563	>	* checked using {@link #getException()} and related methods.
564		*
565		* <p>This method may be invoked only from within {@code
566		* ForkJoinTask} computations (as may be determined using method
#	Line 553 | Line 571 | public abstract class ForkJoinTask<V> im
571		* @param t1 the first task
572		* @param t2 the second task
573		* @throws NullPointerException if any task is null
556	–	* @throws RuntimeException or Error if a task did so
574		*/
575		public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
576		t2.fork();
#	Line 563 | Line 580 | public abstract class ForkJoinTask<V> im
580
581		/**
582		* Forks the given tasks, returning when {@code isDone} holds for
583	<	* each task or an exception is encountered. If any task
584	<	* encounters an exception, others may be, but are not guaranteed
585	<	* to be, cancelled.
583	>	* each task or an (unchecked) exception is encountered, in which
584	>	* case the exception is rethrown. If any task encounters an
585	>	* exception, others may be, but are not guaranteed to be,
586	>	* cancelled.  If more than one task encounters an exception, then
587	>	* this method throws any one of these exceptions.  The individual
588	>	* status of each task may be checked using {@link #getException()}
589	>	* and related methods.
590		*
591		* <p>This method may be invoked only from within {@code
592		* ForkJoinTask} computations (as may be determined using method
#	Line 574 | Line 595 | public abstract class ForkJoinTask<V> im
595		* ClassCastException}.
596		*
597		* @param tasks the tasks
598	<	* @throws NullPointerException if tasks or any element are null
578	<	* @throws RuntimeException or Error if any task did so
598	>	* @throws NullPointerException if any task is null
599		*/
600		public static void invokeAll(ForkJoinTask<?>... tasks) {
601		Throwable ex = null;
#	Line 612 | Line 632 | public abstract class ForkJoinTask<V> im
632
633		/**
634		* Forks all tasks in the specified collection, returning when
635	<	* {@code isDone} holds for each task or an exception is
636	<	* encountered.  If any task encounters an exception, others may
637	<	* be, but are not guaranteed to be, cancelled. The behavior of
638	<	* this operation is undefined if the specified collection is
639	<	* modified while the operation is in progress.
635	>	* {@code isDone} holds for each task or an (unchecked) exception
636	>	* is encountered.  If any task encounters an exception, others
637	>	* may be, but are not guaranteed to be, cancelled.  If more than
638	>	* one task encounters an exception, then this method throws any
639	>	* one of these exceptions.  The individual status of each task
640	>	* may be checked using {@link #getException()} and related
641	>	* methods.  The behavior of this operation is undefined if the
642	>	* specified collection is modified while the operation is in
643	>	* progress.
644		*
645		* <p>This method may be invoked only from within {@code
646		* ForkJoinTask} computations (as may be determined using method
#	Line 627 | Line 651 | public abstract class ForkJoinTask<V> im
651		* @param tasks the collection of tasks
652		* @return the tasks argument, to simplify usage
653		* @throws NullPointerException if tasks or any element are null
630	–	* @throws RuntimeException or Error if any task did so
654		*/
655		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
656		if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
#	Line 671 | Line 694 | public abstract class ForkJoinTask<V> im
694		}
695
696		/**
674	–	* Returns {@code true} if the computation performed by this task
675	–	* has completed (or has been cancelled).
676	–	*
677	–	* @return {@code true} if this computation has completed
678	–	*/
679	–	public final boolean isDone() {
680	–	return status < 0;
681	–	}
682	–
683	–	/**
684	–	* Returns {@code true} if this task was cancelled.
685	–	*
686	–	* @return {@code true} if this task was cancelled
687	–	*/
688	–	public final boolean isCancelled() {
689	–	return (status & COMPLETION_MASK) == CANCELLED;
690	–	}
691	–
692	–	/**
697		* Attempts to cancel execution of this task. This attempt will
698		* fail if the task has already completed, has already been
699		* cancelled, or could not be cancelled for some other reason. If
#	Line 719 | Line 723 | public abstract class ForkJoinTask<V> im
723		}
724
725		/**
726	+	* Returns {@code true} if the computation performed by this task
727	+	* has completed (or has been cancelled).
728	+	*
729	+	* @return {@code true} if this computation has completed
730	+	*/
731	+	public final boolean isDone() {
732	+	return status < 0;
733	+	}
734	+
735	+	/**
736	+	* Returns {@code true} if this task was cancelled.
737	+	*
738	+	* @return {@code true} if this task was cancelled
739	+	*/
740	+	public final boolean isCancelled() {
741	+	return (status & COMPLETION_MASK) == CANCELLED;
742	+	}
743	+
744	+	/**
745		* Returns {@code true} if this task threw an exception or was cancelled.
746		*
747		* @return {@code true} if this task threw an exception or was cancelled
#	Line 728 | Line 751 | public abstract class ForkJoinTask<V> im
751		}
752
753		/**
754	+	* Returns {@code true} if this task completed without throwing an
755	+	* exception and was not cancelled.
756	+	*
757	+	* @return {@code true} if this task completed without throwing an
758	+	* exception and was not cancelled
759	+	*/
760	+	public final boolean isCompletedNormally() {
761	+	return (status & COMPLETION_MASK) == NORMAL;
762	+	}
763	+
764	+	/**
765	+	* Returns {@code true} if this task threw an exception.
766	+	*
767	+	* @return {@code true} if this task threw an exception
768	+	*/
769	+	public final boolean isCompletedExceptionally() {
770	+	return (status & COMPLETION_MASK) == EXCEPTIONAL;
771	+	}
772	+
773	+	/**
774		* Returns the exception thrown by the base computation, or a
775		* {@code CancellationException} if cancelled, or {@code null} if
776		* none or if the method has not yet completed.
#	Line 736 | Line 779 | public abstract class ForkJoinTask<V> im
779		*/
780		public final Throwable getException() {
781		int s = status & COMPLETION_MASK;
782	<	if (s >= NORMAL)
783	<	return null;
784	<	if (s == CANCELLED)
742	<	return new CancellationException();
743	<	return exceptionMap.get(this);
782	>	return ((s >= NORMAL)    ? null :
783	>	(s == CANCELLED) ? new CancellationException() :
784	>	exceptionMap.get(this));
785		}
786
787		/**
#	Line 1020 | Line 1061 | public abstract class ForkJoinTask<V> im
1061		* called otherwise. The return value controls whether this task
1062		* is considered to be done normally. It may return false in
1063		* asynchronous actions that require explicit invocations of
1064	<	* {@link #complete} to become joinable. It may throw exceptions
1065	<	* to indicate abnormal exit.
1064	>	* {@link #complete} to become joinable. It may also throw an
1065	>	* (unchecked) exception to indicate abnormal exit.
1066		*
1067		* @return {@code true} if completed normally
1027	–	* @throws Error or RuntimeException if encountered during computation
1068		*/
1069		protected abstract boolean exec();
1070

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