ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.5 by jsr166, Thu Mar 19 05:10:42 2009 UTC vs.
Revision 1.13 by dl, Wed Jul 22 19:04:11 2009 UTC

#	Line 22 | Line 22 | import java.lang.reflect.*;
22		* <p> A "main" ForkJoinTask begins execution when submitted to a
23		* {@link ForkJoinPool}. Once started, it will usually in turn start
24		* other subtasks.  As indicated by the name of this class, many
25	<	* programs using ForkJoinTasks employ only methods <code>fork</code>
26	<	* and <code>join</code>, or derivatives such as
27	<	* <code>invokeAll</code>.  However, this class also provides a number
25	>	* programs using ForkJoinTasks employ only methods {@code fork}
26	>	* and {@code join}, or derivatives such as
27	>	* {@code invokeAll}.  However, this class also provides a number
28		* of other methods that can come into play in advanced usages, as
29		* well as extension mechanics that allow support of new forms of
30		* fork/join processing.
#	Line 36 | Line 36 | import java.lang.reflect.*;
36		* operating on purely isolated objects.  The primary coordination
37		* mechanisms are {@link #fork}, that arranges asynchronous execution,
38		* and {@link #join}, that doesn't proceed until the task's result has
39	<	* been computed.  Computations should avoid <code>synchronized</code>
39	>	* been computed.  Computations should avoid {@code synchronized}
40		* methods or blocks, and should minimize other blocking
41		* synchronization apart from joining other tasks or using
42		* synchronizers such as Phasers that are advertised to cooperate with
#	Line 48 | Line 48 | import java.lang.reflect.*;
48		* performance, and the potential to indefinitely stall if the number
49		* of threads not waiting for IO or other external synchronization
50		* becomes exhausted. This usage restriction is in part enforced by
51	<	* not permitting checked exceptions such as <code>IOExceptions</code>
51	>	* not permitting checked exceptions such as {@code IOExceptions}
52		* to be thrown. However, computations may still encounter unchecked
53		* exceptions, that are rethrown to callers attempting join
54		* them. These exceptions may additionally include
#	Line 58 | Line 58 | import java.lang.reflect.*;
58		* <p>The primary method for awaiting completion and extracting
59		* results of a task is {@link #join}, but there are several variants:
60		* The {@link Future#get} methods support interruptible and/or timed
61	<	* waits for completion and report results using <code>Future</code>
61	>	* waits for completion and report results using {@code Future}
62		* conventions. Method {@link #helpJoin} enables callers to actively
63		* execute other tasks while awaiting joins, which is sometimes more
64		* efficient but only applies when all subtasks are known to be
65		* strictly tree-structured. Method {@link #invoke} is semantically
66	<	* equivalent to <code>fork(); join()</code> but always attempts to
66	>	* equivalent to {@code fork(); join()} but always attempts to
67		* begin execution in the current thread. The "<em>quiet</em>" forms
68		* of these methods do not extract results or report exceptions. These
69		* may be useful when a set of tasks are being executed, and you need
70		* to delay processing of results or exceptions until all complete.
71	<	* Method <code>invokeAll</code> (available in multiple versions)
71	>	* Method {@code invokeAll} (available in multiple versions)
72		* performs the most common form of parallel invocation: forking a set
73		* of tasks and joining them all.
74		*
#	Line 76 | Line 76 | import java.lang.reflect.*;
76		* Instead, you subclass one of the abstract classes that support a
77		* particular style of fork/join processing.  Normally, a concrete
78		* ForkJoinTask subclass declares fields comprising its parameters,
79	<	* established in a constructor, and then defines a <code>compute</code>
79	>	* established in a constructor, and then defines a {@code compute}
80		* method that somehow uses the control methods supplied by this base
81	<	* class. While these methods have <code>public</code> access (to allow
81	>	* class. While these methods have {@code public} access (to allow
82		* instances of different task subclasses to call each others
83		* methods), some of them may only be called from within other
84	<	* ForkJoinTasks. Attempts to invoke them in other contexts result in
85	<	* exceptions or errors possibly including ClassCastException.
84	>	* ForkJoinTasks (as may be determined using method {@link
85	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
86	>	* result in exceptions or errors possibly including
87	>	* ClassCastException.
88		*
89	<	* <p>Most base support methods are <code>final</code> because their
89	>	* <p>Most base support methods are {@code final} because their
90		* implementations are intrinsically tied to the underlying
91		* lightweight task scheduling framework, and so cannot be overridden.
92		* Developers creating new basic styles of fork/join processing should
93	<	* minimally implement <code>protected</code> methods
94	<	* <code>exec</code>, <code>setRawResult</code>, and
95	<	* <code>getRawResult</code>, while also introducing an abstract
93	>	* minimally implement {@code protected} methods
94	>	* {@code exec}, {@code setRawResult}, and
95	>	* {@code getRawResult}, while also introducing an abstract
96		* computational method that can be implemented in its subclasses,
97	<	* possibly relying on other <code>protected</code> methods provided
97	>	* possibly relying on other {@code protected} methods provided
98		* by this class.
99		*
100		* <p>ForkJoinTasks should perform relatively small amounts of
101	<	* computations, othewise splitting into smaller tasks. As a very
101	>	* computations, otherwise splitting into smaller tasks. As a very
102		* rough rule of thumb, a task should perform more than 100 and less
103		* than 10000 basic computational steps. If tasks are too big, then
104	<	* parellelism cannot improve throughput. If too small, then memory
104	>	* parallelism cannot improve throughput. If too small, then memory
105		* and internal task maintenance overhead may overwhelm processing.
106		*
107	<	* <p>ForkJoinTasks are <code>Serializable</code>, which enables them
107	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them
108		* to be used in extensions such as remote execution frameworks. It is
109		* in general sensible to serialize tasks only before or after, but
110		* not during execution. Serialization is not relied on during
111		* execution itself.
112	+	*
113	+	* @since 1.7
114	+	* @author Doug Lea
115		*/
116		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
117
#	Line 128 | Line 133 | public abstract class ForkJoinTask<V> im
133		* currently unused. Also value 0x80000000 is available as spare
134		* completion value.
135		*/
136	<	volatile int status; // accessed directy by pool and workers
136	>	volatile int status; // accessed directly by pool and workers
137
138		static final int COMPLETION_MASK      = 0xe0000000;
139		static final int NORMAL               = 0xe0000000; // == mask
#	Line 141 | Line 146 | public abstract class ForkJoinTask<V> im
146		/**
147		* Table of exceptions thrown by tasks, to enable reporting by
148		* callers. Because exceptions are rare, we don't directly keep
149	<	* them with task objects, but instead us a weak ref table.  Note
149	>	* them with task objects, but instead use a weak ref table.  Note
150		* that cancellation exceptions don't appear in the table, but are
151		* instead recorded as status values.
152	<	* Todo: Use ConcurrentReferenceHashMap
152	>	* TODO: Use ConcurrentReferenceHashMap
153		*/
154		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
155		Collections.synchronizedMap
#	Line 153 | Line 158 | public abstract class ForkJoinTask<V> im
158		// within-package utilities
159
160		/**
161	<	* Get current worker thread, or null if not a worker thread
161	>	* Gets current worker thread, or null if not a worker thread.
162		*/
163		static ForkJoinWorkerThread getWorker() {
164		Thread t = Thread.currentThread();
#	Line 162 | Line 167 | public abstract class ForkJoinTask<V> im
167		}
168
169		final boolean casStatus(int cmp, int val) {
170	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
170	>	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
171		}
172
173		/**
#	Line 170 | Line 175 | public abstract class ForkJoinTask<V> im
175		*/
176		static void rethrowException(Throwable ex) {
177		if (ex != null)
178	<	_unsafe.throwException(ex);
178	>	UNSAFE.throwException(ex);
179		}
180
181		// Setting completion status
182
183		/**
184	<	* Mark completion and wake up threads waiting to join this task.
184	>	* Marks completion and wakes up threads waiting to join this task.
185	>	*
186		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
187		*/
188		final void setCompletion(int completion) {
#	Line 212 | Line 218 | public abstract class ForkJoinTask<V> im
218		final void setNormalCompletion() {
219		// Try typical fast case -- single CAS, no signal, not already done.
220		// Manually expand casStatus to improve chances of inlining it
221	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
221	>	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
222		setCompletion(NORMAL);
223		}
224
#	Line 255 | Line 261 | public abstract class ForkJoinTask<V> im
261		/**
262		* Sets status to indicate there is joiner, then waits for join,
263		* surrounded with pool notifications.
264	+	*
265		* @return status upon exit
266		*/
267		private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
#	Line 297 | Line 304 | public abstract class ForkJoinTask<V> im
304		}
305
306		/**
307	<	* Notify pool that thread is unblocked. Called by signalled
307	>	* Notifies pool that thread is unblocked. Called by signalled
308		* threads when woken by non-FJ threads (which is atypical).
309		*/
310		private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
#	Line 308 | Line 315 | public abstract class ForkJoinTask<V> im
315		}
316
317		/**
318	<	* Notify pool to adjust counts on cancelled or timed out wait
318	>	* Notifies pool to adjust counts on cancelled or timed out wait.
319		*/
320		private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
321		if (pool != null) {
#	Line 323 | Line 330 | public abstract class ForkJoinTask<V> im
330		}
331
332		/**
333	<	* Handle interruptions during waits.
333	>	* Handles interruptions during waits.
334		*/
335		private void onInterruptedWait() {
336		ForkJoinWorkerThread w = getWorker();
#	Line 342 | Line 349 | public abstract class ForkJoinTask<V> im
349		}
350
351		/**
352	<	* Throws the exception associated with status s;
352	>	* Throws the exception associated with status s.
353	>	*
354		* @throws the exception
355		*/
356		private void reportException(int s) {
#	Line 355 | Line 363 | public abstract class ForkJoinTask<V> im
363		}
364
365		/**
366	<	* Returns result or throws exception using j.u.c.Future conventions
366	>	* Returns result or throws exception using j.u.c.Future conventions.
367		* Only call when isDone known to be true.
368		*/
369		private V reportFutureResult()
#	Line 375 | Line 383 | public abstract class ForkJoinTask<V> im
383
384		/**
385		* Returns result or throws exception using j.u.c.Future conventions
386	<	* with timeouts
386	>	* with timeouts.
387		*/
388		private V reportTimedFutureResult()
389		throws InterruptedException, ExecutionException, TimeoutException {
#	Line 396 | Line 404 | public abstract class ForkJoinTask<V> im
404
405		/**
406		* Calls exec, recording completion, and rethrowing exception if
407	<	* encountered. Caller should normally check status before calling
407	>	* encountered. Caller should normally check status before calling.
408	>	*
409		* @return true if completed normally
410		*/
411		private boolean tryExec() {
#	Line 414 | Line 423 | public abstract class ForkJoinTask<V> im
423
424		/**
425		* Main execution method used by worker threads. Invokes
426	<	* base computation unless already complete
426	>	* base computation unless already complete.
427		*/
428		final void quietlyExec() {
429		if (status >= 0) {
#	Line 430 | Line 439 | public abstract class ForkJoinTask<V> im
439		}
440
441		/**
442	<	* Calls exec, recording but not rethrowing exception
443	<	* Caller should normally check status before calling
442	>	* Calls exec(), recording but not rethrowing exception.
443	>	* Caller should normally check status before calling.
444	>	*
445		* @return true if completed normally
446		*/
447		private boolean tryQuietlyInvoke() {
#	Line 447 | Line 457 | public abstract class ForkJoinTask<V> im
457		}
458
459		/**
460	<	* Cancel, ignoring any exceptions it throws
460	>	* Cancels, ignoring any exceptions it throws.
461		*/
462		final void cancelIgnoringExceptions() {
463		try {
#	Line 474 | Line 484 | public abstract class ForkJoinTask<V> im
484		* necessarily enforced, it is a usage error to fork a task more
485		* than once unless it has completed and been reinitialized.  This
486		* method may be invoked only from within ForkJoinTask
487	<	* computations. Attempts to invoke in other contexts result in
488	<	* exceptions or errors possibly including ClassCastException.
487	>	* computations (as may be determined using method {@link
488	>	* #inForkJoinPool}). Attempts to invoke in other contexts result
489	>	* in exceptions or errors possibly including ClassCastException.
490		*/
491		public final void fork() {
492		((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
#	Line 483 | Line 494 | public abstract class ForkJoinTask<V> im
494
495		/**
496		* Returns the result of the computation when it is ready.
497	<	* This method differs from <code>get</code> in that abnormal
497	>	* This method differs from {@code get} in that abnormal
498		* completion results in RuntimeExceptions or Errors, not
499		* ExecutionExceptions.
500		*
#	Line 499 | Line 510 | public abstract class ForkJoinTask<V> im
510		/**
511		* Commences performing this task, awaits its completion if
512		* necessary, and return its result.
513	+	*
514		* @throws Throwable (a RuntimeException, Error, or unchecked
515	<	* exception) if the underlying computation did so.
515	>	* exception) if the underlying computation did so
516		* @return the computed result
517		*/
518		public final V invoke() {
#	Line 511 | Line 523 | public abstract class ForkJoinTask<V> im
523		}
524
525		/**
526	<	* Forks both tasks, returning when <code>isDone</code> holds for
526	>	* Forks both tasks, returning when {@code isDone} holds for
527		* both of them or an exception is encountered. This method may be
528	<	* invoked only from within ForkJoinTask computations. Attempts to
528	>	* invoked only from within ForkJoinTask computations (as may be
529	>	* determined using method {@link #inForkJoinPool}). Attempts to
530		* invoke in other contexts result in exceptions or errors
531		* possibly including ClassCastException.
532	+	*
533		* @param t1 one task
534		* @param t2 the other task
535		* @throws NullPointerException if t1 or t2 are null
536	<	* @throws RuntimeException or Error if either task did so.
536	>	* @throws RuntimeException or Error if either task did so
537		*/
538		public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
539		t2.fork();
#	Line 528 | Line 542 | public abstract class ForkJoinTask<V> im
542		}
543
544		/**
545	<	* Forks the given tasks, returning when <code>isDone</code> holds
545	>	* Forks the given tasks, returning when {@code isDone} holds
546		* for all of them. If any task encounters an exception, others
547		* may be cancelled.  This method may be invoked only from within
548	<	* ForkJoinTask computations. Attempts to invoke in other contexts
549	<	* result in exceptions or errors possibly including ClassCastException.
548	>	* ForkJoinTask computations (as may be determined using method
549	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
550	>	* result in exceptions or errors possibly including
551	>	* ClassCastException.
552		* @param tasks the array of tasks
553	<	* @throws NullPointerException if tasks or any element are null.
554	<	* @throws RuntimeException or Error if any task did so.
553	>	* @throws NullPointerException if tasks or any element are null
554	>	* @throws RuntimeException or Error if any task did so
555		*/
556		public static void invokeAll(ForkJoinTask<?>... tasks) {
557		Throwable ex = null;
#	Line 572 | Line 588 | public abstract class ForkJoinTask<V> im
588
589		/**
590		* Forks all tasks in the collection, returning when
591	<	* <code>isDone</code> holds for all of them. If any task
591	>	* {@code isDone} holds for all of them. If any task
592		* encounters an exception, others may be cancelled.  This method
593	<	* may be invoked only from within ForkJoinTask
594	<	* computations. Attempts to invoke in other contexts resul!t in
595	<	* exceptions or errors possibly including ClassCastException.
593	>	* may be invoked only from within ForkJoinTask computations (as
594	>	* may be determined using method {@link
595	>	* #inForkJoinPool}). Attempts to invoke in other contexts resul!t
596	>	* in exceptions or errors possibly including ClassCastException.
597	>	*
598		* @param tasks the collection of tasks
599	<	* @throws NullPointerException if tasks or any element are null.
600	<	* @throws RuntimeException or Error if any task did so.
599	>	* @throws NullPointerException if tasks or any element are null
600	>	* @throws RuntimeException or Error if any task did so
601		*/
602		public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
603		if (!(tasks instanceof List)) {
#	Line 623 | Line 641 | public abstract class ForkJoinTask<V> im
641		/**
642		* Returns true if the computation performed by this task has
643		* completed (or has been cancelled).
644	+	*
645		* @return true if this computation has completed
646		*/
647		public final boolean isDone() {
#	Line 631 | Line 650 | public abstract class ForkJoinTask<V> im
650
651		/**
652		* Returns true if this task was cancelled.
653	+	*
654		* @return true if this task was cancelled
655		*/
656		public final boolean isCancelled() {
#	Line 639 | Line 659 | public abstract class ForkJoinTask<V> im
659
660		/**
661		* Asserts that the results of this task's computation will not be
662	<	* used. If a cancellation occurs before atempting to execute this
663	<	* task, then execution will be suppressed, <code>isCancelled</code>
664	<	* will report true, and <code>join</code> will result in a
665	<	* <code>CancellationException</code> being thrown. Otherwise, when
662	>	* used. If a cancellation occurs before attempting to execute this
663	>	* task, then execution will be suppressed, {@code isCancelled}
664	>	* will report true, and {@code join} will result in a
665	>	* {@code CancellationException} being thrown. Otherwise, when
666		* cancellation races with completion, there are no guarantees
667	<	* about whether <code>isCancelled</code> will report true, whether
668	<	* <code>join</code> will return normally or via an exception, or
667	>	* about whether {@code isCancelled} will report true, whether
668	>	* {@code join} will return normally or via an exception, or
669		* whether these behaviors will remain consistent upon repeated
670		* invocation.
671		*
#	Line 656 | Line 676 | public abstract class ForkJoinTask<V> im
676		* <p> This method is designed to be invoked by <em>other</em>
677		* tasks. To terminate the current task, you can just return or
678		* throw an unchecked exception from its computation method, or
679	<	* invoke <code>completeExceptionally</code>.
679	>	* invoke {@code completeExceptionally}.
680		*
681		* @param mayInterruptIfRunning this value is ignored in the
682		* default implementation because tasks are not in general
#	Line 670 | Line 690 | public abstract class ForkJoinTask<V> im
690		}
691
692		/**
693	<	* Returns true if this task threw an exception or was cancelled
693	>	* Returns true if this task threw an exception or was cancelled.
694	>	*
695		* @return true if this task threw an exception or was cancelled
696		*/
697		public final boolean isCompletedAbnormally() {
#	Line 681 | Line 702 | public abstract class ForkJoinTask<V> im
702		* Returns the exception thrown by the base computation, or a
703		* CancellationException if cancelled, or null if none or if the
704		* method has not yet completed.
705	+	*
706		* @return the exception, or null if none
707		*/
708		public final Throwable getException() {
#	Line 695 | Line 717 | public abstract class ForkJoinTask<V> im
717		/**
718		* Completes this task abnormally, and if not already aborted or
719		* cancelled, causes it to throw the given exception upon
720	<	* <code>join</code> and related operations. This method may be used
720	>	* {@code join} and related operations. This method may be used
721		* to induce exceptions in asynchronous tasks, or to force
722		* completion of tasks that would not otherwise complete.  Its use
723		* in other situations is likely to be wrong.  This method is
724	<	* overridable, but overridden versions must invoke <code>super</code>
724	>	* overridable, but overridden versions must invoke {@code super}
725		* implementation to maintain guarantees.
726		*
727		* @param ex the exception to throw. If this exception is
#	Line 714 | Line 736 | public abstract class ForkJoinTask<V> im
736
737		/**
738		* Completes this task, and if not already aborted or cancelled,
739	<	* returning a <code>null</code> result upon <code>join</code> and related
739	>	* returning a {@code null} result upon {@code join} and related
740		* operations. This method may be used to provide results for
741		* asynchronous tasks, or to provide alternative handling for
742		* tasks that would not otherwise complete normally. Its use in
743		* other situations is likely to be wrong. This method is
744	<	* overridable, but overridden versions must invoke <code>super</code>
744	>	* overridable, but overridden versions must invoke {@code super}
745		* implementation to maintain guarantees.
746		*
747	<	* @param value the result value for this task.
747	>	* @param value the result value for this task
748		*/
749		public void complete(V value) {
750		try {
#	Line 752 | Line 774 | public abstract class ForkJoinTask<V> im
774		/**
775		* Possibly executes other tasks until this task is ready, then
776		* returns the result of the computation.  This method may be more
777	<	* efficient than <code>join</code>, but is only applicable when
778	<	* there are no potemtial dependencies between continuation of the
777	>	* efficient than {@code join}, but is only applicable when
778	>	* there are no potential dependencies between continuation of the
779		* current task and that of any other task that might be executed
780		* while helping. (This usually holds for pure divide-and-conquer
781		* tasks). This method may be invoked only from within
782	<	* ForkJoinTask computations. Attempts to invoke in other contexts
783	<	* resul!t in exceptions or errors possibly including ClassCastException.
782	>	* ForkJoinTask computations (as may be determined using method
783	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
784	>	* resul!t in exceptions or errors possibly including
785	>	* ClassCastException.
786	>	*
787		* @return the computed result
788		*/
789		public final V helpJoin() {
#	Line 771 | Line 796 | public abstract class ForkJoinTask<V> im
796		/**
797		* Possibly executes other tasks until this task is ready.  This
798		* method may be invoked only from within ForkJoinTask
799	<	* computations. Attempts to invoke in other contexts resul!t in
800	<	* exceptions or errors possibly including ClassCastException.
799	>	* computations (as may be determined using method {@link
800	>	* #inForkJoinPool}). Attempts to invoke in other contexts resul!t
801	>	* in exceptions or errors possibly including ClassCastException.
802		*/
803		public final void quietlyHelpJoin() {
804		if (status >= 0) {
#	Line 822 | Line 848 | public abstract class ForkJoinTask<V> im
848
849		/**
850		* Resets the internal bookkeeping state of this task, allowing a
851	<	* subsequent <code>fork</code>. This method allows repeated reuse of
851	>	* subsequent {@code fork}. This method allows repeated reuse of
852		* this task, but only if reuse occurs when this task has either
853		* never been forked, or has been forked, then completed and all
854		* outstanding joins of this task have also completed. Effects
#	Line 838 | Line 864 | public abstract class ForkJoinTask<V> im
864
865		/**
866		* Returns the pool hosting the current task execution, or null
867	<	* if this task is executing outside of any pool.
867	>	* if this task is executing outside of any ForkJoinPool.
868	>	*
869		* @return the pool, or null if none.
870		*/
871		public static ForkJoinPool getPool() {
#	Line 848 | Line 875 | public abstract class ForkJoinTask<V> im
875		}
876
877		/**
878	+	* Returns true if the current thread is executing as a
879	+	* ForkJoinPool computation.
880	+	* @return <code>true</code> if the current thread is executing as a
881	+	* ForkJoinPool computation, or false otherwise
882	+	*/
883	+	public static boolean inForkJoinPool() {
884	+	return Thread.currentThread() instanceof ForkJoinWorkerThread;
885	+	}
886	+
887	+	/**
888		* Tries to unschedule this task for execution. This method will
889		* typically succeed if this task is the most recently forked task
890		* by the current thread, and has not commenced executing in
891		* another thread.  This method may be useful when arranging
892		* alternative local processing of tasks that could have been, but
893		* were not, stolen. This method may be invoked only from within
894	<	* ForkJoinTask computations. Attempts to invoke in other contexts
895	<	* result in exceptions or errors possibly including ClassCastException.
894	>	* ForkJoinTask computations (as may be determined using method
895	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
896	>	* result in exceptions or errors possibly including
897	>	* ClassCastException.
898	>	*
899		* @return true if unforked
900		*/
901		public boolean tryUnfork() {
#	Line 867 | Line 907 | public abstract class ForkJoinTask<V> im
907		* forked by the current worker thread but not yet executed. This
908		* value may be useful for heuristic decisions about whether to
909		* fork other tasks.
910	+	*
911		* @return the number of tasks
912		*/
913		public static int getQueuedTaskCount() {
#	Line 875 | Line 916 | public abstract class ForkJoinTask<V> im
916		}
917
918		/**
919	<	* Returns a estimate of how many more locally queued tasks are
919	>	* Returns an estimate of how many more locally queued tasks are
920		* held by the current worker thread than there are other worker
921		* threads that might steal them.  This value may be useful for
922		* heuristic decisions about whether to fork other tasks. In many
#	Line 883 | Line 924 | public abstract class ForkJoinTask<V> im
924		* aim to maintain a small constant surplus (for example, 3) of
925		* tasks, and to process computations locally if this threshold is
926		* exceeded.
927	+	*
928		* @return the surplus number of tasks, which may be negative
929		*/
930		public static int getSurplusQueuedTaskCount() {
#	Line 893 | Line 935 | public abstract class ForkJoinTask<V> im
935		// Extension methods
936
937		/**
938	<	* Returns the result that would be returned by <code>join</code>,
938	>	* Returns the result that would be returned by {@code join},
939		* even if this task completed abnormally, or null if this task is
940		* not known to have been completed.  This method is designed to
941		* aid debugging, as well as to support extensions. Its use in any
942		* other context is discouraged.
943		*
944	<	* @return the result, or null if not completed.
944	>	* @return the result, or null if not completed
945		*/
946		public abstract V getRawResult();
947
#	Line 918 | Line 960 | public abstract class ForkJoinTask<V> im
960		* called otherwise. The return value controls whether this task
961		* is considered to be done normally. It may return false in
962		* asynchronous actions that require explicit invocations of
963	<	* <code>complete</code> to become joinable. It may throw exceptions
963	>	* {@code complete} to become joinable. It may throw exceptions
964		* to indicate abnormal exit.
965	+	*
966		* @return true if completed normally
967		* @throws Error or RuntimeException if encountered during computation
968		*/
969		protected abstract boolean exec();
970
971		/**
972	<	* Returns, but does not unschedule or execute, the task most
973	<	* recently forked by the current thread but not yet executed, if
974	<	* one is available. There is no guarantee that this task will
975	<	* actually be polled or executed next.
976	<	* This method is designed primarily to support extensions,
977	<	* and is unlikely to be useful otherwise.
978	<	* This method may be invoked only from within
979	<	* ForkJoinTask computations. Attempts to invoke in other contexts
980	<	* result in exceptions or errors possibly including ClassCastException.
972	>	* Returns, but does not unschedule or execute, the task queued by
973	>	* the current thread but not yet executed, if one is
974	>	* available. There is no guarantee that this task will actually
975	>	* be polled or executed next.  This method is designed primarily
976	>	* to support extensions, and is unlikely to be useful otherwise.
977	>	* This method may be invoked only from within ForkJoinTask
978	>	* computations (as may be determined using method {@link
979	>	* #inForkJoinPool}). Attempts to invoke in other contexts result
980	>	* in exceptions or errors possibly including ClassCastException.
981		*
982		* @return the next task, or null if none are available
983		*/
#	Line 943 | Line 986 | public abstract class ForkJoinTask<V> im
986		}
987
988		/**
989	<	* Unschedules and returns, without executing, the task most
990	<	* recently forked by the current thread but not yet executed.
991	<	* This method is designed primarily to support extensions,
992	<	* and is unlikely to be useful otherwise.
993	<	* This method may be invoked only from within
994	<	* ForkJoinTask computations. Attempts to invoke in other contexts
995	<	* result in exceptions or errors possibly including ClassCastException.
989	>	* Unschedules and returns, without executing, the next task
990	>	* queued by the current thread but not yet executed.  This method
991	>	* is designed primarily to support extensions, and is unlikely to
992	>	* be useful otherwise.  This method may be invoked only from
993	>	* within ForkJoinTask computations (as may be determined using
994	>	* method {@link #inForkJoinPool}). Attempts to invoke in other
995	>	* contexts result in exceptions or errors possibly including
996	>	* ClassCastException.
997		*
998		* @return the next task, or null if none are available
999		*/
1000		protected static ForkJoinTask<?> pollNextLocalTask() {
1001	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).popTask();
1001	>	return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask();
1002		}
1003
1004		/**
1005	<	* Unschedules and returns, without executing, the task most
1006	<	* recently forked by the current thread but not yet executed, if
1007	<	* one is available, or if not available, a task that was forked
1008	<	* by some other thread, if available. Availability may be
1009	<	* transient, so a <code>null</code> result does not necessarily
1010	<	* imply quiecence of the pool this task is operating in.
1011	<	* This method is designed primarily to support extensions,
1012	<	* and is unlikely to be useful otherwise.
1013	<	* This method may be invoked only from within
1014	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1015	<	* result in exceptions or errors possibly including ClassCastException.
1005	>	* Unschedules and returns, without executing, the next task
1006	>	* queued by the current thread but not yet executed, if one is
1007	>	* available, or if not available, a task that was forked by some
1008	>	* other thread, if available. Availability may be transient, so a
1009	>	* {@code null} result does not necessarily imply quiescence
1010	>	* of the pool this task is operating in.  This method is designed
1011	>	* primarily to support extensions, and is unlikely to be useful
1012	>	* otherwise.  This method may be invoked only from within
1013	>	* ForkJoinTask computations (as may be determined using method
1014	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1015	>	* result in exceptions or errors possibly including
1016	>	* ClassCastException.
1017		*
1018		* @return a task, or null if none are available
1019		*/
#	Line 985 | Line 1030 | public abstract class ForkJoinTask<V> im
1030		* Save the state to a stream.
1031		*
1032		* @serialData the current run status and the exception thrown
1033	<	* during execution, or null if none.
1033	>	* during execution, or null if none
1034		* @param s the stream
1035		*/
1036		private void writeObject(java.io.ObjectOutputStream s)
#	Line 996 | Line 1041 | public abstract class ForkJoinTask<V> im
1041
1042		/**
1043		* Reconstitute the instance from a stream.
1044	+	*
1045		* @param s the stream
1046		*/
1047		private void readObject(java.io.ObjectInputStream s)
#	Line 1034 | Line 1080 | public abstract class ForkJoinTask<V> im
1080
1081		private static long fieldOffset(String fieldName)
1082		throws NoSuchFieldException {
1083	<	return _unsafe.objectFieldOffset
1083	>	return UNSAFE.objectFieldOffset
1084		(ForkJoinTask.class.getDeclaredField(fieldName));
1085		}
1086
1087	<	static final Unsafe _unsafe;
1087	>	static final Unsafe UNSAFE;
1088		static final long statusOffset;
1089
1090		static {
1091		try {
1092	<	_unsafe = getUnsafe();
1092	>	UNSAFE = getUnsafe();
1093		statusOffset = fieldOffset("status");
1094		} catch (Throwable e) {
1095		throw new RuntimeException("Could not initialize intrinsics", e);

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines