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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.52 by dl, Sat Jul 24 20:28:18 2010 UTC vs.
Revision 1.72 by dl, Wed Nov 24 10:50:38 2010 UTC

#	Line 6 | Line 6
6
7		package jsr166y;
8
9	–	import java.util.concurrent.*;
10	–
9		import java.io.Serializable;
10		import java.util.Collection;
11		import java.util.Collections;
#	Line 15 | Line 13 | import java.util.List;
13		import java.util.RandomAccess;
14		import java.util.Map;
15		import java.util.WeakHashMap;
16	+	import java.util.concurrent.Callable;
17	+	import java.util.concurrent.CancellationException;
18	+	import java.util.concurrent.ExecutionException;
19	+	import java.util.concurrent.Executor;
20	+	import java.util.concurrent.ExecutorService;
21	+	import java.util.concurrent.Future;
22	+	import java.util.concurrent.RejectedExecutionException;
23	+	import java.util.concurrent.RunnableFuture;
24	+	import java.util.concurrent.TimeUnit;
25	+	import java.util.concurrent.TimeoutException;
26
27		/**
28		* Abstract base class for tasks that run within a {@link ForkJoinPool}.
#	Line 28 | Line 36 | import java.util.WeakHashMap;
36		* start other subtasks.  As indicated by the name of this class,
37		* many programs using {@code ForkJoinTask} employ only methods
38		* {@link #fork} and {@link #join}, or derivatives such as {@link
39	<	* #invokeAll}.  However, this class also provides a number of other
40	<	* methods that can come into play in advanced usages, as well as
41	<	* extension mechanics that allow support of new forms of fork/join
42	<	* processing.
39	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
40	>	* provides a number of other methods that can come into play in
41	>	* advanced usages, as well as extension mechanics that allow
42	>	* support of new forms of fork/join processing.
43		*
44		* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
45		* The efficiency of {@code ForkJoinTask}s stems from a set of
#	Line 100 | Line 108 | import java.util.WeakHashMap;
108		* ForkJoinTasks (as may be determined using method {@link
109		* #inForkJoinPool}).  Attempts to invoke them in other contexts
110		* result in exceptions or errors, possibly including
111	<	* ClassCastException.
111	>	* {@code ClassCastException}.
112	>	*
113	>	* <p>Method {@link #join} and its variants are appropriate for use
114	>	* only when completion dependencies are acyclic; that is, the
115	>	* parallel computation can be described as a directed acyclic graph
116	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
117	>	* tasks cyclically wait for each other.  However, this framework
118	>	* supports other methods and techniques (for example the use of
119	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
120	>	* may be of use in constructing custom subclasses for problems that
121	>	* are not statically structured as DAGs.
122		*
123		* <p>Most base support methods are {@code final}, to prevent
124		* overriding of implementations that are intrinsically tied to the
#	Line 116 | Line 134 | import java.util.WeakHashMap;
134		* computation. Large tasks should be split into smaller subtasks,
135		* usually via recursive decomposition. As a very rough rule of thumb,
136		* a task should perform more than 100 and less than 10000 basic
137	<	* computational steps. If tasks are too big, then parallelism cannot
138	<	* improve throughput. If too small, then memory and internal task
139	<	* maintenance overhead may overwhelm processing.
137	>	* computational steps, and should avoid indefinite looping. If tasks
138	>	* are too big, then parallelism cannot improve throughput. If too
139	>	* small, then memory and internal task maintenance overhead may
140	>	* overwhelm processing.
141		*
142		* <p>This class provides {@code adapt} methods for {@link Runnable}
143		* and {@link Callable}, that may be of use when mixing execution of
#	Line 144 | Line 163 | public abstract class ForkJoinTask<V> im
163		* status maintenance (2) execution and awaiting completion (3)
164		* user-level methods that additionally report results. This is
165		* sometimes hard to see because this file orders exported methods
166	<	* in a way that flows well in javadocs.
166	>	* in a way that flows well in javadocs. In particular, most
167	>	* join mechanics are in method quietlyJoin, below.
168		*/
169
170		/*
#	Line 152 | Line 172 | public abstract class ForkJoinTask<V> im
172		* single int to minimize footprint and to ensure atomicity (via
173		* CAS).  Status is initially zero, and takes on nonnegative
174		* values until completed, upon which status holds value
175	<	* COMPLETED. CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
175	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
176		* waits by other threads have the SIGNAL bit set.  Completion of
177		* a stolen task with SIGNAL set awakens any waiters via
178		* notifyAll. Even though suboptimal for some purposes, we use
#	Line 164 | Line 184 | public abstract class ForkJoinTask<V> im
184		* them.
185		*/
186
187	<	/** Run status of this task */
187	>	/** The run status of this task */
188		volatile int status; // accessed directly by pool and workers
189
190		private static final int NORMAL      = -1;
#	Line 191 | Line 211 | public abstract class ForkJoinTask<V> im
211		* also clearing signal request bits.
212		*
213		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
194	–	* @return status on exit
214		*/
215	<	private int setCompletion(int completion) {
215	>	private void setCompletion(int completion) {
216		int s;
217		while ((s = status) >= 0) {
218		if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
219		if (s != 0)
220		synchronized (this) { notifyAll(); }
221	<	return completion;
221	>	break;
222		}
223		}
205	–	return s;
224		}
225
226		/**
227	<	* Record exception and set exceptional completion
227	>	* Records exception and sets exceptional completion.
228	>	*
229		* @return status on exit
230		*/
231	<	private int setExceptionalCompletion(Throwable rex) {
231	>	private void setExceptionalCompletion(Throwable rex) {
232		exceptionMap.put(this, rex);
233	<	return setCompletion(EXCEPTIONAL);
233	>	setCompletion(EXCEPTIONAL);
234		}
235
236		/**
237	<	* Blocks a worker thread until completion. Called only by pool.
237	>	* Blocks a worker thread until completed or timed out.  Called
238	>	* only by pool.
239		*/
240	<	final void internalAwaitDone() {
241	<	int s;         // the odd construction reduces lock bias effects
242	<	while ((s = status) >= 0) {
243	<	try {
244	<	synchronized(this) {
245	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
246	<	wait();
240	>	final void internalAwaitDone(long millis, int nanos) {
241	>	int s = status;
242	>	if ((s == 0 &&
243	>	UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL)) ||
244	>	s > 0)  {
245	>	try {     // the odd construction reduces lock bias effects
246	>	synchronized (this) {
247	>	if (status > 0)
248	>	wait(millis, nanos);
249	>	else
250	>	notifyAll();
251		}
252		} catch (InterruptedException ie) {
253		cancelIfTerminating();
#	Line 233 | Line 257 | public abstract class ForkJoinTask<V> im
257
258		/**
259		* Blocks a non-worker-thread until completion.
236	–	* @return status on exit
260		*/
261	<	private int externalAwaitDone() {
262	<	int s;
263	<	while ((s = status) >= 0) {
261	>	private void externalAwaitDone() {
262	>	if (status >= 0) {
263	>	boolean interrupted = false;
264		synchronized(this) {
265	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
266	<	boolean interrupted = false;
267	<	while ((s = status) >= 0) {
265	>	for (;;) {
266	>	int s = status;
267	>	if (s == 0)
268	>	UNSAFE.compareAndSwapInt(this, statusOffset,
269	>	0, SIGNAL);
270	>	else if (s < 0) {
271	>	notifyAll();
272	>	break;
273	>	}
274	>	else {
275		try {
276		wait();
277		} catch (InterruptedException ie) {
278		interrupted = true;
279		}
280		}
281	<	if (interrupted)
282	<	Thread.currentThread().interrupt();
283	<	break;
281	>	}
282	>	}
283	>	if (interrupted)
284	>	Thread.currentThread().interrupt();
285	>	}
286	>	}
287	>
288	>	/**
289	>	* Blocks a non-worker-thread until completion or interruption or timeout.
290	>	*/
291	>	private void externalInterruptibleAwaitDone(boolean timed, long nanos)
292	>	throws InterruptedException {
293	>	if (Thread.interrupted())
294	>	throw new InterruptedException();
295	>	if (status >= 0) {
296	>	long startTime = timed ? System.nanoTime() : 0L;
297	>	synchronized(this) {
298	>	for (;;) {
299	>	long nt;
300	>	int s = status;
301	>	if (s == 0)
302	>	UNSAFE.compareAndSwapInt(this, statusOffset,
303	>	0, SIGNAL);
304	>	else if (s < 0) {
305	>	notifyAll();
306	>	break;
307	>	}
308	>	else if (!timed)
309	>	wait();
310	>	else if ((nt = nanos - (System.nanoTime()-startTime)) > 0L)
311	>	wait(nt / 1000000, (int)(nt % 1000000));
312	>	else
313	>	break;
314		}
315		}
316		}
257	–	return s;
317		}
318
319		/**
#	Line 262 | Line 321 | public abstract class ForkJoinTask<V> im
321		* doesn't wait for completion otherwise. Primary execution method
322		* for ForkJoinWorkerThread.
323		*/
324	<	final void tryExec() {
324	>	final void quietlyExec() {
325		try {
326		if (status < 0 || !exec())
327		return;
#	Line 273 | Line 332 | public abstract class ForkJoinTask<V> im
332		setCompletion(NORMAL); // must be outside try block
333		}
334
276	–	/**
277	–	* If not done and this task is next in worker queue, runs it,
278	–	* else waits for it.
279	–	* @return status on exit
280	–	*/
281	–	private int doJoin() {
282	–	int stat;
283	–	Thread t;
284	–	ForkJoinWorkerThread w;
285	–	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
286	–	if ((stat = status) < 0)
287	–	return stat;
288	–	if ((w = (ForkJoinWorkerThread) t).unpushTask(this)) {
289	–	boolean completed;
290	–	try {
291	–	completed = exec();
292	–	} catch (Throwable rex) {
293	–	return setExceptionalCompletion(rex);
294	–	}
295	–	if (completed)
296	–	return setCompletion(NORMAL);
297	–	}
298	–	return w.joinTask(this);
299	–	}
300	–	return externalAwaitDone();
301	–	}
302	–
303	–	/**
304	–	* Unless done, calls exec and records status if completed, or
305	–	* waits for completion otherwise.
306	–	* @return status on exit
307	–	*/
308	–	private int doInvoke() {
309	–	int stat;
310	–	if ((stat = status) >= 0) {
311	–	boolean completed;
312	–	try {
313	–	completed = exec();
314	–	} catch (Throwable rex) {
315	–	return setExceptionalCompletion(rex);
316	–	}
317	–	stat = completed ? setCompletion(NORMAL) : doJoin();
318	–	}
319	–	return stat;
320	–	}
321	–
322	–	/**
323	–	* Returns result or throws exception associated with given status.
324	–	* @param s the status
325	–	*/
326	–	private V reportResult(int s) {
327	–	Throwable ex;
328	–	if (s < NORMAL && (ex = getException()) != null)
329	–	UNSAFE.throwException(ex);
330	–	return getRawResult();
331	–	}
332	–
335		// public methods
336
337		/**
#	Line 343 | Line 345 | public abstract class ForkJoinTask<V> im
345		* #isDone} returning {@code true}.
346		*
347		* <p>This method may be invoked only from within {@code
348	<	* ForkJoinTask} computations (as may be determined using method
348	>	* ForkJoinPool} computations (as may be determined using method
349		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
350		* result in exceptions or errors, possibly including {@code
351		* ClassCastException}.
#	Line 357 | Line 359 | public abstract class ForkJoinTask<V> im
359		}
360
361		/**
362	<	* Returns the result of the computation when it {@link #isDone is done}.
363	<	* This method differs from {@link #get()} in that
362	>	* Returns the result of the computation when it {@link #isDone is
363	>	* done}.  This method differs from {@link #get()} in that
364		* abnormal completion results in {@code RuntimeException} or
365	<	* {@code Error}, not {@code ExecutionException}.
365	>	* {@code Error}, not {@code ExecutionException}, and that
366	>	* interrupts of the calling thread do <em>not</em> cause the
367	>	* method to abruptly return by throwing {@code
368	>	* InterruptedException}.
369		*
370		* @return the computed result
371		*/
372		public final V join() {
373	<	return reportResult(doJoin());
373	>	quietlyJoin();
374	>	Throwable ex;
375	>	if (status < NORMAL && (ex = getException()) != null)
376	>	UNSAFE.throwException(ex);
377	>	return getRawResult();
378		}
379
380		/**
381		* Commences performing this task, awaits its completion if
382	<	* necessary, and return its result, or throws an (unchecked)
383	<	* exception if the underlying computation did so.
382	>	* necessary, and returns its result, or throws an (unchecked)
383	>	* {@code RuntimeException} or {@code Error} if the underlying
384	>	* computation did so.
385		*
386		* @return the computed result
387		*/
388		public final V invoke() {
389	<	return reportResult(doInvoke());
389	>	quietlyInvoke();
390	>	Throwable ex;
391	>	if (status < NORMAL && (ex = getException()) != null)
392	>	UNSAFE.throwException(ex);
393	>	return getRawResult();
394		}
395
396		/**
397		* Forks the given tasks, returning when {@code isDone} holds for
398		* each task or an (unchecked) exception is encountered, in which
399	<	* case the exception is rethrown.  If either task encounters an
400	<	* exception, the other one may be, but is not guaranteed to be,
401	<	* cancelled.  If both tasks throw an exception, then this method
402	<	* throws one of them.  The individual status of each task may be
403	<	* checked using {@link #getException()} and related methods.
399	>	* case the exception is rethrown. If more than one task
400	>	* encounters an exception, then this method throws any one of
401	>	* these exceptions. If any task encounters an exception, the
402	>	* other may be cancelled. However, the execution status of
403	>	* individual tasks is not guaranteed upon exceptional return. The
404	>	* status of each task may be obtained using {@link
405	>	* #getException()} and related methods to check if they have been
406	>	* cancelled, completed normally or exceptionally, or left
407	>	* unprocessed.
408		*
409		* <p>This method may be invoked only from within {@code
410	<	* ForkJoinTask} computations (as may be determined using method
410	>	* ForkJoinPool} computations (as may be determined using method
411		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
412		* result in exceptions or errors, possibly including {@code
413		* ClassCastException}.
#	Line 407 | Line 425 | public abstract class ForkJoinTask<V> im
425		/**
426		* Forks the given tasks, returning when {@code isDone} holds for
427		* each task or an (unchecked) exception is encountered, in which
428	<	* case the exception is rethrown. If any task encounters an
429	<	* exception, others may be, but are not guaranteed to be,
430	<	* cancelled.  If more than one task encounters an exception, then
431	<	* this method throws any one of these exceptions.  The individual
432	<	* status of each task may be checked using {@link #getException()}
433	<	* and related methods.
428	>	* case the exception is rethrown. If more than one task
429	>	* encounters an exception, then this method throws any one of
430	>	* these exceptions. If any task encounters an exception, others
431	>	* may be cancelled. However, the execution status of individual
432	>	* tasks is not guaranteed upon exceptional return. The status of
433	>	* each task may be obtained using {@link #getException()} and
434	>	* related methods to check if they have been cancelled, completed
435	>	* normally or exceptionally, or left unprocessed.
436		*
437		* <p>This method may be invoked only from within {@code
438	<	* ForkJoinTask} computations (as may be determined using method
438	>	* ForkJoinPool} computations (as may be determined using method
439		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
440		* result in exceptions or errors, possibly including {@code
441		* ClassCastException}.
#	Line 434 | Line 454 | public abstract class ForkJoinTask<V> im
454		}
455		else if (i != 0)
456		t.fork();
457	<	else if (t.doInvoke() < NORMAL && ex == null)
458	<	ex = t.getException();
457	>	else {
458	>	t.quietlyInvoke();
459	>	if (ex == null && t.status < NORMAL)
460	>	ex = t.getException();
461	>	}
462		}
463		for (int i = 1; i <= last; ++i) {
464		ForkJoinTask<?> t = tasks[i];
465		if (t != null) {
466		if (ex != null)
467		t.cancel(false);
468	<	else if (t.doJoin() < NORMAL && ex == null)
469	<	ex = t.getException();
468	>	else {
469	>	t.quietlyJoin();
470	>	if (ex == null && t.status < NORMAL)
471	>	ex = t.getException();
472	>	}
473		}
474		}
475		if (ex != null)
#	Line 453 | Line 479 | public abstract class ForkJoinTask<V> im
479		/**
480		* Forks all tasks in the specified collection, returning when
481		* {@code isDone} holds for each task or an (unchecked) exception
482	<	* is encountered.  If any task encounters an exception, others
483	<	* may be, but are not guaranteed to be, cancelled.  If more than
484	<	* one task encounters an exception, then this method throws any
485	<	* one of these exceptions.  The individual status of each task
486	<	* may be checked using {@link #getException()} and related
487	<	* methods.  The behavior of this operation is undefined if the
488	<	* specified collection is modified while the operation is in
489	<	* progress.
482	>	* is encountered, in which case the exception is rethrown. If
483	>	* more than one task encounters an exception, then this method
484	>	* throws any one of these exceptions. If any task encounters an
485	>	* exception, others may be cancelled. However, the execution
486	>	* status of individual tasks is not guaranteed upon exceptional
487	>	* return. The status of each task may be obtained using {@link
488	>	* #getException()} and related methods to check if they have been
489	>	* cancelled, completed normally or exceptionally, or left
490	>	* unprocessed.
491		*
492		* <p>This method may be invoked only from within {@code
493	<	* ForkJoinTask} computations (as may be determined using method
493	>	* ForkJoinPool} computations (as may be determined using method
494		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
495		* result in exceptions or errors, possibly including {@code
496		* ClassCastException}.
#	Line 490 | Line 517 | public abstract class ForkJoinTask<V> im
517		}
518		else if (i != 0)
519		t.fork();
520	<	else if (t.doInvoke() < NORMAL && ex == null)
521	<	ex = t.getException();
520	>	else {
521	>	t.quietlyInvoke();
522	>	if (ex == null && t.status < NORMAL)
523	>	ex = t.getException();
524	>	}
525		}
526		for (int i = 1; i <= last; ++i) {
527		ForkJoinTask<?> t = ts.get(i);
528		if (t != null) {
529		if (ex != null)
530		t.cancel(false);
531	<	else if (t.doJoin() < NORMAL && ex == null)
532	<	ex = t.getException();
531	>	else {
532	>	t.quietlyJoin();
533	>	if (ex == null && t.status < NORMAL)
534	>	ex = t.getException();
535	>	}
536		}
537		}
538		if (ex != null)
#	Line 509 | Line 542 | public abstract class ForkJoinTask<V> im
542
543		/**
544		* Attempts to cancel execution of this task. This attempt will
545	<	* fail if the task has already completed, has already been
546	<	* cancelled, or could not be cancelled for some other reason. If
547	<	* successful, and this task has not started when cancel is
548	<	* called, execution of this task is suppressed, {@link
549	<	* #isCancelled} will report true, and {@link #join} will result
550	<	* in a {@code CancellationException} being thrown.
545	>	* fail if the task has already completed or could not be
546	>	* cancelled for some other reason. If successful, and this task
547	>	* has not started when {@code cancel} is called, execution of
548	>	* this task is suppressed. After this method returns
549	>	* successfully, unless there is an intervening call to {@link
550	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
551	>	* {@link #isDone}, and {@code cancel} will return {@code true}
552	>	* and calls to {@link #join} and related methods will result in
553	>	* {@code CancellationException}.
554		*
555		* <p>This method may be overridden in subclasses, but if so, must
556	<	* still ensure that these minimal properties hold. In particular,
557	<	* the {@code cancel} method itself must not throw exceptions.
556	>	* still ensure that these properties hold. In particular, the
557	>	* {@code cancel} method itself must not throw exceptions.
558		*
559		* <p>This method is designed to be invoked by <em>other</em>
560		* tasks. To terminate the current task, you can just return or
561		* throw an unchecked exception from its computation method, or
562		* invoke {@link #completeExceptionally}.
563		*
564	<	* @param mayInterruptIfRunning this value is ignored in the
565	<	* default implementation because tasks are not
566	<	* cancelled via interruption
564	>	* @param mayInterruptIfRunning this value has no effect in the
565	>	* default implementation because interrupts are not used to
566	>	* control cancellation.
567		*
568		* @return {@code true} if this task is now cancelled
569		*/
570		public boolean cancel(boolean mayInterruptIfRunning) {
571	<	return setCompletion(CANCELLED) == CANCELLED;
571	>	setCompletion(CANCELLED);
572	>	return status == CANCELLED;
573		}
574
575		/**
#	Line 549 | Line 586 | public abstract class ForkJoinTask<V> im
586		}
587
588		/**
589	<	* Cancels ignoring exceptions if worker is terminating
589	>	* Cancels if current thread is a terminating worker thread,
590	>	* ignoring any exceptions thrown by cancel.
591		*/
592		final void cancelIfTerminating() {
593		Thread t = Thread.currentThread();
#	Line 626 | Line 664 | public abstract class ForkJoinTask<V> im
664
665		/**
666		* Completes this task, and if not already aborted or cancelled,
667	<	* returning a {@code null} result upon {@code join} and related
668	<	* operations. This method may be used to provide results for
669	<	* asynchronous tasks, or to provide alternative handling for
670	<	* tasks that would not otherwise complete normally. Its use in
671	<	* other situations is discouraged. This method is
672	<	* overridable, but overridden versions must invoke {@code super}
673	<	* implementation to maintain guarantees.
667	>	* returning the given value as the result of subsequent
668	>	* invocations of {@code join} and related operations. This method
669	>	* may be used to provide results for asynchronous tasks, or to
670	>	* provide alternative handling for tasks that would not otherwise
671	>	* complete normally. Its use in other situations is
672	>	* discouraged. This method is overridable, but overridden
673	>	* versions must invoke {@code super} implementation to maintain
674	>	* guarantees.
675		*
676		* @param value the result value for this task
677		*/
#	Line 646 | Line 685 | public abstract class ForkJoinTask<V> im
685		setCompletion(NORMAL);
686		}
687
688	+	/**
689	+	* Waits if necessary for the computation to complete, and then
690	+	* retrieves its result.
691	+	*
692	+	* @return the computed result
693	+	* @throws CancellationException if the computation was cancelled
694	+	* @throws ExecutionException if the computation threw an
695	+	* exception
696	+	* @throws InterruptedException if the current thread is not a
697	+	* member of a ForkJoinPool and was interrupted while waiting
698	+	*/
699		public final V get() throws InterruptedException, ExecutionException {
700	<	int s = doJoin();
701	<	if (Thread.interrupted())
702	<	throw new InterruptedException();
703	<	if (s < NORMAL) {
700	>	Thread t = Thread.currentThread();
701	>	if (t instanceof ForkJoinWorkerThread)
702	>	quietlyJoin();
703	>	else
704	>	externalInterruptibleAwaitDone(false, 0L);
705	>	int s = status;
706	>	if (s != NORMAL) {
707		Throwable ex;
708		if (s == CANCELLED)
709		throw new CancellationException();
#	Line 660 | Line 713 | public abstract class ForkJoinTask<V> im
713		return getRawResult();
714		}
715
716	+	/**
717	+	* Waits if necessary for at most the given time for the computation
718	+	* to complete, and then retrieves its result, if available.
719	+	*
720	+	* @param timeout the maximum time to wait
721	+	* @param unit the time unit of the timeout argument
722	+	* @return the computed result
723	+	* @throws CancellationException if the computation was cancelled
724	+	* @throws ExecutionException if the computation threw an
725	+	* exception
726	+	* @throws InterruptedException if the current thread is not a
727	+	* member of a ForkJoinPool and was interrupted while waiting
728	+	* @throws TimeoutException if the wait timed out
729	+	*/
730		public final V get(long timeout, TimeUnit unit)
731		throws InterruptedException, ExecutionException, TimeoutException {
732	+	long nanos = unit.toNanos(timeout);
733		Thread t = Thread.currentThread();
734	<	ForkJoinPool pool;
735	<	if (t instanceof ForkJoinWorkerThread) {
668	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
669	<	if (status >= 0 && w.unpushTask(this))
670	<	tryExec();
671	<	pool = w.pool;
672	<	}
734	>	if (t instanceof ForkJoinWorkerThread)
735	>	((ForkJoinWorkerThread)t).joinTask(this, true, nanos);
736		else
737	<	pool = null;
738	<	/*
739	<	* Timed wait loop intermixes cases for FJ (pool != null) and
677	<	* non FJ threads. For FJ, decrement pool count but don't try
678	<	* for replacement; increment count on completion. For non-FJ,
679	<	* deal with interrupts. This is messy, but a little less so
680	<	* than is splitting the FJ and nonFJ cases.
681	<	*/
682	<	boolean interrupted = false;
683	<	boolean dec = false; // true if pool count decremented
684	<	for (;;) {
685	<	if (Thread.interrupted() && pool == null) {
686	<	interrupted = true;
687	<	break;
688	<	}
689	<	int s = status;
690	<	if (s < 0)
691	<	break;
692	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
693	<	long startTime = System.nanoTime();
694	<	long nanos = unit.toNanos(timeout);
695	<	long nt; // wait time
696	<	while (status >= 0 &&
697	<	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
698	<	if (pool != null && !dec)
699	<	dec = pool.tryDecrementRunningCount();
700	<	else {
701	<	long ms = nt / 1000000;
702	<	int ns = (int) (nt % 1000000);
703	<	try {
704	<	synchronized(this) {
705	<	if (status >= 0)
706	<	wait(ms, ns);
707	<	}
708	<	} catch (InterruptedException ie) {
709	<	if (pool != null)
710	<	cancelIfTerminating();
711	<	else {
712	<	interrupted = true;
713	<	break;
714	<	}
715	<	}
716	<	}
717	<	}
718	<	break;
719	<	}
720	<	}
721	<	if (pool != null && dec)
722	<	pool.incrementRunningCount();
723	<	if (interrupted)
724	<	throw new InterruptedException();
725	<	int es = status;
726	<	if (es != NORMAL) {
737	>	externalInterruptibleAwaitDone(true, nanos);
738	>	int s = status;
739	>	if (s != NORMAL) {
740		Throwable ex;
741	<	if (es == CANCELLED)
741	>	if (s == CANCELLED)
742		throw new CancellationException();
743	<	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
743	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
744		throw new ExecutionException(ex);
745		throw new TimeoutException();
746		}
#	Line 735 | Line 748 | public abstract class ForkJoinTask<V> im
748		}
749
750		/**
751	<	* Joins this task, without returning its result or throwing an
751	>	* Joins this task, without returning its result or throwing its
752		* exception. This method may be useful when processing
753		* collections of tasks when some have been cancelled or otherwise
754		* known to have aborted.
755		*/
756		public final void quietlyJoin() {
757	<	doJoin();
757	>	Thread t;
758	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
759	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
760	>	if (status >= 0) {
761	>	if (w.unpushTask(this)) {
762	>	boolean completed;
763	>	try {
764	>	completed = exec();
765	>	} catch (Throwable rex) {
766	>	setExceptionalCompletion(rex);
767	>	return;
768	>	}
769	>	if (completed) {
770	>	setCompletion(NORMAL);
771	>	return;
772	>	}
773	>	}
774	>	w.joinTask(this, false, 0L);
775	>	}
776	>	}
777	>	else
778	>	externalAwaitDone();
779		}
780
781		/**
782		* Commences performing this task and awaits its completion if
783	<	* necessary, without returning its result or throwing an
784	<	* exception. This method may be useful when processing
751	<	* collections of tasks when some have been cancelled or otherwise
752	<	* known to have aborted.
783	>	* necessary, without returning its result or throwing its
784	>	* exception.
785		*/
786		public final void quietlyInvoke() {
787	<	doInvoke();
787	>	if (status >= 0) {
788	>	boolean completed;
789	>	try {
790	>	completed = exec();
791	>	} catch (Throwable rex) {
792	>	setExceptionalCompletion(rex);
793	>	return;
794	>	}
795	>	if (completed)
796	>	setCompletion(NORMAL);
797	>	else
798	>	quietlyJoin();
799	>	}
800		}
801
802		/**
#	Line 763 | Line 807 | public abstract class ForkJoinTask<V> im
807		* processed.
808		*
809		* <p>This method may be invoked only from within {@code
810	<	* ForkJoinTask} computations (as may be determined using method
810	>	* ForkJoinPool} computations (as may be determined using method
811		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
812		* result in exceptions or errors, possibly including {@code
813		* ClassCastException}.
#	Line 782 | Line 826 | public abstract class ForkJoinTask<V> im
826		* under any other usage conditions are not guaranteed.
827		* This method may be useful when executing
828		* pre-constructed trees of subtasks in loops.
829	+	*
830	+	* <p>Upon completion of this method, {@code isDone()} reports
831	+	* {@code false}, and {@code getException()} reports {@code
832	+	* null}. However, the value returned by {@code getRawResult} is
833	+	* unaffected. To clear this value, you can invoke {@code
834	+	* setRawResult(null)}.
835		*/
836		public void reinitialize() {
837		if (status == EXCEPTIONAL)
#	Line 803 | Line 853 | public abstract class ForkJoinTask<V> im
853		}
854
855		/**
856	<	* Returns {@code true} if the current thread is executing as a
857	<	* ForkJoinPool computation.
856	>	* Returns {@code true} if the current thread is a {@link
857	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
858		*
859	<	* @return {@code true} if the current thread is executing as a
860	<	* ForkJoinPool computation, or false otherwise
859	>	* @return {@code true} if the current thread is a {@link
860	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
861	>	* or {@code false} otherwise
862		*/
863		public static boolean inForkJoinPool() {
864		return Thread.currentThread() instanceof ForkJoinWorkerThread;
#	Line 822 | Line 873 | public abstract class ForkJoinTask<V> im
873		* were not, stolen.
874		*
875		* <p>This method may be invoked only from within {@code
876	<	* ForkJoinTask} computations (as may be determined using method
876	>	* ForkJoinPool} computations (as may be determined using method
877		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
878		* result in exceptions or errors, possibly including {@code
879		* ClassCastException}.
#	Line 841 | Line 892 | public abstract class ForkJoinTask<V> im
892		* fork other tasks.
893		*
894		* <p>This method may be invoked only from within {@code
895	<	* ForkJoinTask} computations (as may be determined using method
895	>	* ForkJoinPool} computations (as may be determined using method
896		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
897		* result in exceptions or errors, possibly including {@code
898		* ClassCastException}.
#	Line 864 | Line 915 | public abstract class ForkJoinTask<V> im
915		* exceeded.
916		*
917		* <p>This method may be invoked only from within {@code
918	<	* ForkJoinTask} computations (as may be determined using method
918	>	* ForkJoinPool} computations (as may be determined using method
919		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
920		* result in exceptions or errors, possibly including {@code
921		* ClassCastException}.
#	Line 922 | Line 973 | public abstract class ForkJoinTask<V> im
973		* otherwise.
974		*
975		* <p>This method may be invoked only from within {@code
976	<	* ForkJoinTask} computations (as may be determined using method
976	>	* ForkJoinPool} computations (as may be determined using method
977		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
978		* result in exceptions or errors, possibly including {@code
979		* ClassCastException}.
#	Line 941 | Line 992 | public abstract class ForkJoinTask<V> im
992		* be useful otherwise.
993		*
994		* <p>This method may be invoked only from within {@code
995	<	* ForkJoinTask} computations (as may be determined using method
995	>	* ForkJoinPool} computations (as may be determined using method
996		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
997		* result in exceptions or errors, possibly including {@code
998		* ClassCastException}.
#	Line 964 | Line 1015 | public abstract class ForkJoinTask<V> im
1015		* otherwise.
1016		*
1017		* <p>This method may be invoked only from within {@code
1018	<	* ForkJoinTask} computations (as may be determined using method
1018	>	* ForkJoinPool} computations (as may be determined using method
1019		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1020		* result in exceptions or errors, possibly including {@code
1021		* ClassCastException}.
#	Line 1074 | Line 1125 | public abstract class ForkJoinTask<V> im
1125		private static final long serialVersionUID = -7721805057305804111L;
1126
1127		/**
1128	<	* Saves the state to a stream.
1128	>	* Saves the state to a stream (that is, serializes it).
1129		*
1130		* @serialData the current run status and the exception thrown
1131		* during execution, or {@code null} if none
#	Line 1087 | Line 1138 | public abstract class ForkJoinTask<V> im
1138		}
1139
1140		/**
1141	<	* Reconstitutes the instance from a stream.
1141	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1142		*
1143		* @param s the stream
1144		*/

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