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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.46 by dl, Mon Apr 5 15:52:26 2010 UTC vs.
Revision 1.65 by jsr166, Sat Oct 16 16:37:30 2010 UTC

#	Line 7 | Line 7
7		package jsr166y;
8
9		import java.util.concurrent.*;
10	–
10		import java.io.Serializable;
11		import java.util.Collection;
12		import java.util.Collections;
#	Line 28 | Line 27 | import java.util.WeakHashMap;
27		* start other subtasks.  As indicated by the name of this class,
28		* many programs using {@code ForkJoinTask} employ only methods
29		* {@link #fork} and {@link #join}, or derivatives such as {@link
30	<	* #invokeAll}.  However, this class also provides a number of other
31	<	* methods that can come into play in advanced usages, as well as
32	<	* extension mechanics that allow support of new forms of fork/join
33	<	* processing.
30	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
31	>	* provides a number of other methods that can come into play in
32	>	* advanced usages, as well as extension mechanics that allow
33	>	* support of new forms of fork/join processing.
34		*
35		* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
36		* The efficiency of {@code ForkJoinTask}s stems from a set of
#	Line 64 | Line 63 | import java.util.WeakHashMap;
63		* results of a task is {@link #join}, but there are several variants:
64		* The {@link Future#get} methods support interruptible and/or timed
65		* waits for completion and report results using {@code Future}
66	<	* conventions. Method {@link #helpJoin} enables callers to actively
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
66	>	* conventions. Method {@link #invoke} is semantically
67		* equivalent to {@code fork(); join()} but always attempts to begin
68		* execution in the current thread. The "<em>quiet</em>" forms of
69		* these methods do not extract results or report exceptions. These
#	Line 103 | Line 99 | import java.util.WeakHashMap;
99		* ForkJoinTasks (as may be determined using method {@link
100		* #inForkJoinPool}).  Attempts to invoke them in other contexts
101		* result in exceptions or errors, possibly including
102	<	* ClassCastException.
102	>	* {@code ClassCastException}.
103		*
104		* <p>Most base support methods are {@code final}, to prevent
105		* overriding of implementations that are intrinsically tied to the
#	Line 125 | Line 121 | import java.util.WeakHashMap;
121		*
122		* <p>This class provides {@code adapt} methods for {@link Runnable}
123		* and {@link Callable}, that may be of use when mixing execution of
124	<	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
125	<	* are of this form, consider using a pool in
130	<	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
124	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
125	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
126		*
127		* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
128		* used in extensions such as remote execution frameworks. It is
#	Line 148 | Line 143 | public abstract class ForkJoinTask<V> im
143		* status maintenance (2) execution and awaiting completion (3)
144		* user-level methods that additionally report results. This is
145		* sometimes hard to see because this file orders exported methods
146	<	* in a way that flows well in javadocs.
146	>	* in a way that flows well in javadocs. In particular, most
147	>	* join mechanics are in method quietlyJoin, below.
148		*/
149
150	<	/**
151	<	* Run control status bits packed into a single int to minimize
152	<	* footprint and to ensure atomicity (via CAS).  Status is
153	<	* initially zero, and takes on nonnegative values until
154	<	* completed, upon which status holds COMPLETED. CANCELLED, or
155	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
156	<	* blocking waits by other threads have SIGNAL_MASK bits set --
157	<	* bit 15 for external (nonFJ) waits, and the rest a count of
158	<	* waiting FJ threads.  (This representation relies on
159	<	* ForkJoinPool max thread limits). Signal counts are not directly
160	<	* incremented by ForkJoinTask methods, but instead via a call to
161	<	* requestSignal within ForkJoinPool.preJoin, once their need is
162	<	* established.
163	<	*
164	<	* Completion of a stolen task with SIGNAL_MASK bits set awakens
169	<	* any waiters via notifyAll. Even though suboptimal for some
170	<	* purposes, we use basic builtin wait/notify to take advantage of
171	<	* "monitor inflation" in JVMs that we would otherwise need to
172	<	* emulate to avoid adding further per-task bookkeeping overhead.
173	<	* We want these monitors to be "fat", i.e., not use biasing or
174	<	* thin-lock techniques, so use some odd coding idioms that tend
175	<	* to avoid them.
176	<	*
177	<	* Note that bits 16-28 are currently unused. Also value
178	<	* 0x80000000 is available as spare completion value.
150	>	/*
151	>	* The status field holds run control status bits packed into a
152	>	* single int to minimize footprint and to ensure atomicity (via
153	>	* CAS).  Status is initially zero, and takes on nonnegative
154	>	* values until completed, upon which status holds value
155	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
156	>	* waits by other threads have the SIGNAL bit set.  Completion of
157	>	* a stolen task with SIGNAL set awakens any waiters via
158	>	* notifyAll. Even though suboptimal for some purposes, we use
159	>	* basic builtin wait/notify to take advantage of "monitor
160	>	* inflation" in JVMs that we would otherwise need to emulate to
161	>	* avoid adding further per-task bookkeeping overhead.  We want
162	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
163	>	* techniques, so use some odd coding idioms that tend to avoid
164	>	* them.
165		*/
166	+
167	+	/** The run status of this task */
168		volatile int status; // accessed directly by pool and workers
169
170	<	private static final int COMPLETION_MASK      = 0xe0000000;
171	<	private static final int NORMAL               = 0xe0000000; // == mask
172	<	private static final int CANCELLED            = 0xc0000000;
173	<	private static final int EXCEPTIONAL          = 0xa0000000;
186	<	private static final int SIGNAL_MASK          = 0x0000ffff;
187	<	private static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
188	<	private static final int EXTERNAL_SIGNAL      = 0x00008000;
170	>	private static final int NORMAL      = -1;
171	>	private static final int CANCELLED   = -2;
172	>	private static final int EXCEPTIONAL = -3;
173	>	private static final int SIGNAL      =  1;
174
175		/**
176		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 211 | Line 196 | public abstract class ForkJoinTask<V> im
196		int s;
197		while ((s = status) >= 0) {
198		if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
199	<	if ((s & SIGNAL_MASK) != 0) {
215	<	Thread t = Thread.currentThread();
216	<	if (t instanceof ForkJoinWorkerThread)
217	<	((ForkJoinWorkerThread) t).pool.updateRunningCount
218	<	(s & INTERNAL_SIGNAL_MASK);
199	>	if (s != 0)
200		synchronized (this) { notifyAll(); }
201	<	}
221	<	return;
201	>	break;
202		}
203		}
204		}
205
206		/**
207	<	* Record exception and set exceptional completion
207	>	* Records exception and sets exceptional completion.
208	>	*
209	>	* @return status on exit
210		*/
211	<	private void setDoneExceptionally(Throwable rex) {
211	>	private void setExceptionalCompletion(Throwable rex) {
212		exceptionMap.put(this, rex);
213		setCompletion(EXCEPTIONAL);
214		}
215
216		/**
217	<	* Main internal execution method: Unless done, calls exec and
218	<	* records completion.
219	<	*
238	<	* @return true if ran and completed normally
217	>	* Blocks a worker thread until completion. Called only by
218	>	* pool. Currently unused -- pool-based waits use timeout
219	>	* version below.
220		*/
221	<	final boolean tryExec() {
222	<	try {
223	<	if (status < 0 || !exec())
224	<	return false;
225	<	} catch (Throwable rex) {
226	<	setDoneExceptionally(rex);
227	<	return false;
221	>	final void internalAwaitDone() {
222	>	int s;         // the odd construction reduces lock bias effects
223	>	while ((s = status) >= 0) {
224	>	try {
225	>	synchronized (this) {
226	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
227	>	wait();
228	>	}
229	>	} catch (InterruptedException ie) {
230	>	cancelIfTerminating();
231	>	}
232		}
248	–	setCompletion(NORMAL); // must be outside try block
249	–	return true;
233		}
234
235		/**
236	<	* Increments internal signal count (thus requesting signal upon
237	<	* completion) unless already done.  Call only once per join.
255	<	* Used by ForkJoinPool.preJoin.
256	<	*
257	<	* @return status
258	<	*/
259	<	final int requestSignal() {
260	<	int s;
261	<	do {} while ((s = status) >= 0 &&
262	<	!UNSAFE.compareAndSwapInt(this, statusOffset, s, s + 1));
263	<	return s;
264	<	}
265	<
266	<	/**
267	<	* Sets external signal request unless already done.
236	>	* Blocks a worker thread until completed or timed out.  Called
237	>	* only by pool.
238		*
239	<	* @return status
239	>	* @return status on exit
240		*/
241	<	private int requestExternalSignal() {
241	>	final int internalAwaitDone(long millis) {
242		int s;
243	<	do {} while ((s = status) >= 0 &&
244	<	!UNSAFE.compareAndSwapInt(this, statusOffset,
245	<	s, s | EXTERNAL_SIGNAL));
246	<	return s;
247	<	}
278	<
279	<	/*
280	<	* Awaiting completion. The four versions, internal vs external X
281	<	* untimed vs timed, have the same overall structure but differ
282	<	* from each other enough to defy simple integration.
283	<	*/
284	<
285	<	/**
286	<	* Blocks a worker until this task is done, also maintaining pool
287	<	* and signal counts
288	<	*/
289	<	private void awaitDone(ForkJoinWorkerThread w) {
290	<	if (status >= 0) {
291	<	w.pool.preJoin(this);
292	<	while (status >= 0) {
293	<	try { // minimize lock scope
294	<	synchronized(this) {
295	<	if (status >= 0)
296	<	wait();
297	<	else { // help release; also helps avoid lock-biasing
298	<	notifyAll();
299	<	break;
300	<	}
301	<	}
302	<	} catch (InterruptedException ie) {
303	<	cancelIfTerminating();
243	>	if ((s = status) >= 0) {
244	>	try {
245	>	synchronized (this) {
246	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
247	>	wait(millis, 0);
248		}
249	+	} catch (InterruptedException ie) {
250	+	cancelIfTerminating();
251		}
252	+	s = status;
253		}
254	+	return s;
255		}
256
257		/**
258	<	* Blocks a non-ForkJoin thread until this task is done.
258	>	* Blocks a non-worker-thread until completion.
259		*/
260		private void externalAwaitDone() {
261	<	if (requestExternalSignal() >= 0) {
262	<	boolean interrupted = false;
263	<	while (status >= 0) {
264	<	try {
265	<	synchronized(this) {
266	<	if (status >= 0)
267	<	wait();
268	<	else {
269	<	notifyAll();
270	<	break;
323	<	}
324	<	}
325	<	} catch (InterruptedException ie) {
326	<	interrupted = true;
327	<	}
328	<	}
329	<	if (interrupted)
330	<	Thread.currentThread().interrupt();
331	<	}
332	<	}
333	<
334	<	/**
335	<	* Blocks a worker until this task is done or timeout elapses
336	<	*/
337	<	private void timedAwaitDone(ForkJoinWorkerThread w, long nanos) {
338	<	if (status >= 0) {
339	<	long startTime = System.nanoTime();
340	<	ForkJoinPool pool = w.pool;
341	<	pool.preJoin(this);
342	<	while (status >= 0) {
343	<	long nt = nanos - (System.nanoTime() - startTime);
344	<	if (nt > 0) {
345	<	long ms = nt / 1000000;
346	<	int ns = (int) (nt % 1000000);
347	<	try {
348	<	synchronized(this) { if (status >= 0) wait(ms, ns); }
349	<	} catch (InterruptedException ie) {
350	<	cancelIfTerminating();
351	<	}
352	<	}
353	<	else {
354	<	int s; // adjust running count on timeout
355	<	while ((s = status) >= 0 &&
356	<	(s & INTERNAL_SIGNAL_MASK) != 0) {
357	<	if (UNSAFE.compareAndSwapInt(this, statusOffset,
358	<	s, s - 1)) {
359	<	pool.updateRunningCount(1);
360	<	break;
261	>	int s;
262	>	while ((s = status) >= 0) {
263	>	synchronized (this) {
264	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
265	>	boolean interrupted = false;
266	>	while (status >= 0) {
267	>	try {
268	>	wait();
269	>	} catch (InterruptedException ie) {
270	>	interrupted = true;
271		}
272		}
273	+	if (interrupted)
274	+	Thread.currentThread().interrupt();
275		break;
276		}
277		}
#	Line 367 | Line 279 | public abstract class ForkJoinTask<V> im
279		}
280
281		/**
282	<	* Blocks a non-ForkJoin thread until this task is done or timeout elapses
283	<	*/
284	<	private void externalTimedAwaitDone(long nanos) {
373	<	if (requestExternalSignal() >= 0) {
374	<	long startTime = System.nanoTime();
375	<	boolean interrupted = false;
376	<	while (status >= 0) {
377	<	long nt = nanos - (System.nanoTime() - startTime);
378	<	if (nt <= 0)
379	<	break;
380	<	long ms = nt / 1000000;
381	<	int ns = (int) (nt % 1000000);
382	<	try {
383	<	synchronized(this) { if (status >= 0) wait(ms, ns); }
384	<	} catch (InterruptedException ie) {
385	<	interrupted = true;
386	<	}
387	<	}
388	<	if (interrupted)
389	<	Thread.currentThread().interrupt();
390	<	}
391	<	}
392	<
393	<	// reporting results
394	<
395	<	/**
396	<	* Returns result or throws the exception associated with status.
397	<	* Uses Unsafe as a workaround for javac not allowing rethrow of
398	<	* unchecked exceptions.
282	>	* Unless done, calls exec and records status if completed, but
283	>	* doesn't wait for completion otherwise. Primary execution method
284	>	* for ForkJoinWorkerThread.
285		*/
286	<	private V reportResult() {
287	<	if ((status & COMPLETION_MASK) < NORMAL) {
288	<	Throwable ex = getException();
289	<	if (ex != null)
290	<	UNSAFE.throwException(ex);
291	<	}
292	<	return getRawResult();
407	<	}
408	<
409	<	/**
410	<	* Returns result or throws exception using j.u.c.Future conventions.
411	<	* Only call when {@code isDone} known to be true or thread known
412	<	* to be interrupted.
413	<	*/
414	<	private V reportFutureResult()
415	<	throws InterruptedException, ExecutionException {
416	<	if (Thread.interrupted())
417	<	throw new InterruptedException();
418	<	int s = status & COMPLETION_MASK;
419	<	if (s < NORMAL) {
420	<	Throwable ex;
421	<	if (s == CANCELLED)
422	<	throw new CancellationException();
423	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
424	<	throw new ExecutionException(ex);
286	>	final void quietlyExec() {
287	>	try {
288	>	if (status < 0 || !exec())
289	>	return;
290	>	} catch (Throwable rex) {
291	>	setExceptionalCompletion(rex);
292	>	return;
293		}
294	<	return getRawResult();
427	<	}
428	<
429	<	/**
430	<	* Returns result or throws exception using j.u.c.Future conventions
431	<	* with timeouts.
432	<	*/
433	<	private V reportTimedFutureResult()
434	<	throws InterruptedException, ExecutionException, TimeoutException {
435	<	if (Thread.interrupted())
436	<	throw new InterruptedException();
437	<	Throwable ex;
438	<	int s = status & COMPLETION_MASK;
439	<	if (s == NORMAL)
440	<	return getRawResult();
441	<	else if (s == CANCELLED)
442	<	throw new CancellationException();
443	<	else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
444	<	throw new ExecutionException(ex);
445	<	else
446	<	throw new TimeoutException();
294	>	setCompletion(NORMAL); // must be outside try block
295		}
296
297		// public methods
#	Line 482 | Line 330 | public abstract class ForkJoinTask<V> im
330		*/
331		public final V join() {
332		quietlyJoin();
333	<	return reportResult();
333	>	Throwable ex;
334	>	if (status < NORMAL && (ex = getException()) != null)
335	>	UNSAFE.throwException(ex);
336	>	return getRawResult();
337		}
338
339		/**
340		* Commences performing this task, awaits its completion if
341	<	* necessary, and return its result, or throws an (unchecked)
342	<	* exception if the underlying computation did so.
341	>	* necessary, and returns its result, or throws an (unchecked)
342	>	* {@code RuntimeException} or {@code Error} if the underlying
343	>	* computation did so.
344		*
345		* @return the computed result
346		*/
347		public final V invoke() {
348	<	if (!tryExec())
349	<	quietlyJoin();
350	<	return reportResult();
348	>	quietlyInvoke();
349	>	Throwable ex;
350	>	if (status < NORMAL && (ex = getException()) != null)
351	>	UNSAFE.throwException(ex);
352	>	return getRawResult();
353		}
354
355		/**
356		* Forks the given tasks, returning when {@code isDone} holds for
357		* each task or an (unchecked) exception is encountered, in which
358	<	* case the exception is rethrown.  If either task encounters an
359	<	* exception, the other one may be, but is not guaranteed to be,
360	<	* cancelled.  If both tasks throw an exception, then this method
361	<	* throws one of them.  The individual status of each task may be
362	<	* checked using {@link #getException()} and related methods.
358	>	* case the exception is rethrown. If more than one task
359	>	* encounters an exception, then this method throws any one of
360	>	* these exceptions. If any task encounters an exception, the
361	>	* other may be cancelled. However, the execution status of
362	>	* individual tasks is not guaranteed upon exceptional return. The
363	>	* status of each task may be obtained using {@link
364	>	* #getException()} and related methods to check if they have been
365	>	* cancelled, completed normally or exceptionally, or left
366	>	* unprocessed.
367		*
368		* <p>This method may be invoked only from within {@code
369		* ForkJoinTask} computations (as may be determined using method
#	Line 526 | Line 384 | public abstract class ForkJoinTask<V> im
384		/**
385		* Forks the given tasks, returning when {@code isDone} holds for
386		* each task or an (unchecked) exception is encountered, in which
387	<	* case the exception is rethrown. If any task encounters an
388	<	* exception, others may be, but are not guaranteed to be,
389	<	* cancelled.  If more than one task encounters an exception, then
390	<	* this method throws any one of these exceptions.  The individual
391	<	* status of each task may be checked using {@link #getException()}
392	<	* and related methods.
387	>	* case the exception is rethrown. If more than one task
388	>	* encounters an exception, then this method throws any one of
389	>	* these exceptions. If any task encounters an exception, others
390	>	* may be cancelled. However, the execution status of individual
391	>	* tasks is not guaranteed upon exceptional return. The status of
392	>	* each task may be obtained using {@link #getException()} and
393	>	* related methods to check if they have been cancelled, completed
394	>	* normally or exceptionally, or left unprocessed.
395		*
396		* <p>This method may be invoked only from within {@code
397		* ForkJoinTask} computations (as may be determined using method
#	Line 555 | Line 415 | public abstract class ForkJoinTask<V> im
415		t.fork();
416		else {
417		t.quietlyInvoke();
418	<	if (ex == null)
418	>	if (ex == null && t.status < NORMAL)
419		ex = t.getException();
420		}
421		}
#	Line 566 | Line 426 | public abstract class ForkJoinTask<V> im
426		t.cancel(false);
427		else {
428		t.quietlyJoin();
429	<	if (ex == null)
429	>	if (ex == null && t.status < NORMAL)
430		ex = t.getException();
431		}
432		}
#	Line 578 | Line 438 | public abstract class ForkJoinTask<V> im
438		/**
439		* Forks all tasks in the specified collection, returning when
440		* {@code isDone} holds for each task or an (unchecked) exception
441	<	* is encountered.  If any task encounters an exception, others
442	<	* may be, but are not guaranteed to be, cancelled.  If more than
443	<	* one task encounters an exception, then this method throws any
444	<	* one of these exceptions.  The individual status of each task
445	<	* may be checked using {@link #getException()} and related
446	<	* methods.  The behavior of this operation is undefined if the
447	<	* specified collection is modified while the operation is in
448	<	* progress.
441	>	* is encountered, in which case the exception is rethrown. If
442	>	* more than one task encounters an exception, then this method
443	>	* throws any one of these exceptions. If any task encounters an
444	>	* exception, others may be cancelled. However, the execution
445	>	* status of individual tasks is not guaranteed upon exceptional
446	>	* return. The status of each task may be obtained using {@link
447	>	* #getException()} and related methods to check if they have been
448	>	* cancelled, completed normally or exceptionally, or left
449	>	* unprocessed.
450		*
451		* <p>This method may be invoked only from within {@code
452		* ForkJoinTask} computations (as may be determined using method
#	Line 617 | Line 478 | public abstract class ForkJoinTask<V> im
478		t.fork();
479		else {
480		t.quietlyInvoke();
481	<	if (ex == null)
481	>	if (ex == null && t.status < NORMAL)
482		ex = t.getException();
483		}
484		}
#	Line 628 | Line 489 | public abstract class ForkJoinTask<V> im
489		t.cancel(false);
490		else {
491		t.quietlyJoin();
492	<	if (ex == null)
492	>	if (ex == null && t.status < NORMAL)
493		ex = t.getException();
494		}
495		}
#	Line 664 | Line 525 | public abstract class ForkJoinTask<V> im
525		*/
526		public boolean cancel(boolean mayInterruptIfRunning) {
527		setCompletion(CANCELLED);
528	<	return (status & COMPLETION_MASK) == CANCELLED;
528	>	return status == CANCELLED;
529		}
530
531		/**
532	<	* Cancels, ignoring any exceptions it throws. Used during worker
533	<	* and pool shutdown.
532	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
533	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
534	>	* exceptions, but if it does anyway, we have no recourse during
535	>	* shutdown, so guard against this case.
536		*/
537		final void cancelIgnoringExceptions() {
538		try {
#	Line 679 | Line 542 | public abstract class ForkJoinTask<V> im
542		}
543
544		/**
545	<	* Cancels ignoring exceptions if worker is terminating
545	>	* Cancels if current thread is a terminating worker thread,
546	>	* ignoring any exceptions thrown by cancel.
547		*/
548	<	private void cancelIfTerminating() {
548	>	final void cancelIfTerminating() {
549		Thread t = Thread.currentThread();
550		if ((t instanceof ForkJoinWorkerThread) &&
551	<	((ForkJoinWorkerThread) t).isTerminating()) {
551	>	((ForkJoinWorkerThread) t).isTerminating()) {
552		try {
553		cancel(false);
554		} catch (Throwable ignore) {
#	Line 697 | Line 561 | public abstract class ForkJoinTask<V> im
561		}
562
563		public final boolean isCancelled() {
564	<	return (status & COMPLETION_MASK) == CANCELLED;
564	>	return status == CANCELLED;
565		}
566
567		/**
#	Line 706 | Line 570 | public abstract class ForkJoinTask<V> im
570		* @return {@code true} if this task threw an exception or was cancelled
571		*/
572		public final boolean isCompletedAbnormally() {
573	<	return (status & COMPLETION_MASK) < NORMAL;
573	>	return status < NORMAL;
574		}
575
576		/**
#	Line 717 | Line 581 | public abstract class ForkJoinTask<V> im
581		* exception and was not cancelled
582		*/
583		public final boolean isCompletedNormally() {
584	<	return (status & COMPLETION_MASK) == NORMAL;
584	>	return status == NORMAL;
585		}
586
587		/**
#	Line 728 | Line 592 | public abstract class ForkJoinTask<V> im
592		* @return the exception, or {@code null} if none
593		*/
594		public final Throwable getException() {
595	<	int s = status & COMPLETION_MASK;
595	>	int s = status;
596		return ((s >= NORMAL)    ? null :
597		(s == CANCELLED) ? new CancellationException() :
598		exceptionMap.get(this));
#	Line 749 | Line 613 | public abstract class ForkJoinTask<V> im
613		* thrown will be a {@code RuntimeException} with cause {@code ex}.
614		*/
615		public void completeExceptionally(Throwable ex) {
616	<	setDoneExceptionally((ex instanceof RuntimeException) ||
617	<	(ex instanceof Error) ? ex :
618	<	new RuntimeException(ex));
616	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
617	>	(ex instanceof Error) ? ex :
618	>	new RuntimeException(ex));
619		}
620
621		/**
622		* Completes this task, and if not already aborted or cancelled,
623	<	* returning a {@code null} result upon {@code join} and related
624	<	* operations. This method may be used to provide results for
625	<	* asynchronous tasks, or to provide alternative handling for
626	<	* tasks that would not otherwise complete normally. Its use in
627	<	* other situations is discouraged. This method is
628	<	* overridable, but overridden versions must invoke {@code super}
629	<	* implementation to maintain guarantees.
623	>	* returning the given value as the result of subsequent
624	>	* invocations of {@code join} and related operations. This method
625	>	* may be used to provide results for asynchronous tasks, or to
626	>	* provide alternative handling for tasks that would not otherwise
627	>	* complete normally. Its use in other situations is
628	>	* discouraged. This method is overridable, but overridden
629	>	* versions must invoke {@code super} implementation to maintain
630	>	* guarantees.
631		*
632		* @param value the result value for this task
633		*/
#	Line 770 | Line 635 | public abstract class ForkJoinTask<V> im
635		try {
636		setRawResult(value);
637		} catch (Throwable rex) {
638	<	setDoneExceptionally(rex);
638	>	setExceptionalCompletion(rex);
639		return;
640		}
641		setCompletion(NORMAL);
642		}
643
779	–	public final V get() throws InterruptedException, ExecutionException {
780	–	quietlyJoin();
781	–	return reportFutureResult();
782	–	}
783	–
784	–	public final V get(long timeout, TimeUnit unit)
785	–	throws InterruptedException, ExecutionException, TimeoutException {
786	–	long nanos = unit.toNanos(timeout);
787	–	Thread t = Thread.currentThread();
788	–	if (t instanceof ForkJoinWorkerThread) {
789	–	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
790	–	if (!w.unpushTask(this) || !tryExec())
791	–	timedAwaitDone(w, nanos);
792	–	}
793	–	else
794	–	externalTimedAwaitDone(nanos);
795	–	return reportTimedFutureResult();
796	–	}
797	–
644		/**
645	<	* Possibly executes other tasks until this task {@link #isDone is
646	<	* done}, then returns the result of the computation.  This method
801	<	* may be more efficient than {@code join}, but is only applicable
802	<	* when there are no potential dependencies between continuation
803	<	* of the current task and that of any other task that might be
804	<	* executed while helping. (This usually holds for pure
805	<	* divide-and-conquer tasks).
806	<	*
807	<	* <p>This method may be invoked only from within {@code
808	<	* ForkJoinTask} computations (as may be determined using method
809	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
810	<	* result in exceptions or errors, possibly including {@code
811	<	* ClassCastException}.
645	>	* Waits if necessary for the computation to complete, and then
646	>	* retrieves its result.
647		*
648		* @return the computed result
649	+	* @throws CancellationException if the computation was cancelled
650	+	* @throws ExecutionException if the computation threw an
651	+	* exception
652	+	* @throws InterruptedException if the current thread is not a
653	+	* member of a ForkJoinPool and was interrupted while waiting
654		*/
655	<	public final V helpJoin() {
656	<	quietlyHelpJoin();
657	<	return reportResult();
655	>	public final V get() throws InterruptedException, ExecutionException {
656	>	int s;
657	>	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
658	>	quietlyJoin();
659	>	s = status;
660	>	}
661	>	else {
662	>	while ((s = status) >= 0) {
663	>	synchronized (this) { // interruptible form of awaitDone
664	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
665	>	s, SIGNAL)) {
666	>	while (status >= 0)
667	>	wait();
668	>	}
669	>	}
670	>	}
671	>	}
672	>	if (s < NORMAL) {
673	>	Throwable ex;
674	>	if (s == CANCELLED)
675	>	throw new CancellationException();
676	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
677	>	throw new ExecutionException(ex);
678	>	}
679	>	return getRawResult();
680		}
681
682		/**
683	<	* Possibly executes other tasks until this task {@link #isDone is
684	<	* done}.  This method may be useful when processing collections
823	<	* of tasks when some have been cancelled or otherwise known to
824	<	* have aborted.
683	>	* Waits if necessary for at most the given time for the computation
684	>	* to complete, and then retrieves its result, if available.
685		*
686	<	* <p>This method may be invoked only from within {@code
687	<	* ForkJoinTask} computations (as may be determined using method
688	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
689	<	* result in exceptions or errors, possibly including {@code
690	<	* ClassCastException}.
686	>	* @param timeout the maximum time to wait
687	>	* @param unit the time unit of the timeout argument
688	>	* @return the computed result
689	>	* @throws CancellationException if the computation was cancelled
690	>	* @throws ExecutionException if the computation threw an
691	>	* exception
692	>	* @throws InterruptedException if the current thread is not a
693	>	* member of a ForkJoinPool and was interrupted while waiting
694	>	* @throws TimeoutException if the wait timed out
695		*/
696	<	public final void quietlyHelpJoin() {
697	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
698	<	if (!w.unpushTask(this) || !tryExec()) {
699	<	while (status >= 0) {
700	<	ForkJoinTask<?> t = w.scanWhileJoining(this);
701	<	if (t == null) {
702	<	if (status >= 0)
703	<	awaitDone(w);
704	<	break;
696	>	public final V get(long timeout, TimeUnit unit)
697	>	throws InterruptedException, ExecutionException, TimeoutException {
698	>	Thread t = Thread.currentThread();
699	>	ForkJoinPool pool;
700	>	if (t instanceof ForkJoinWorkerThread) {
701	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
702	>	if (status >= 0 && w.unpushTask(this))
703	>	quietlyExec();
704	>	pool = w.pool;
705	>	}
706	>	else
707	>	pool = null;
708	>	/*
709	>	* Timed wait loop intermixes cases for FJ (pool != null) and
710	>	* non FJ threads. For FJ, decrement pool count but don't try
711	>	* for replacement; increment count on completion. For non-FJ,
712	>	* deal with interrupts. This is messy, but a little less so
713	>	* than is splitting the FJ and nonFJ cases.
714	>	*/
715	>	boolean interrupted = false;
716	>	boolean dec = false; // true if pool count decremented
717	>	long nanos = unit.toNanos(timeout);
718	>	for (;;) {
719	>	if (pool == null && Thread.interrupted()) {
720	>	interrupted = true;
721	>	break;
722	>	}
723	>	int s = status;
724	>	if (s < 0)
725	>	break;
726	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
727	>	long startTime = System.nanoTime();
728	>	long nt; // wait time
729	>	while (status >= 0 &&
730	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
731	>	if (pool != null && !dec)
732	>	dec = pool.tryDecrementRunningCount();
733	>	else {
734	>	long ms = nt / 1000000;
735	>	int ns = (int) (nt % 1000000);
736	>	try {
737	>	synchronized (this) {
738	>	if (status >= 0)
739	>	wait(ms, ns);
740	>	}
741	>	} catch (InterruptedException ie) {
742	>	if (pool != null)
743	>	cancelIfTerminating();
744	>	else {
745	>	interrupted = true;
746	>	break;
747	>	}
748	>	}
749	>	}
750		}
751	<	t.tryExec();
751	>	break;
752		}
753		}
754	+	if (pool != null && dec)
755	+	pool.incrementRunningCount();
756	+	if (interrupted)
757	+	throw new InterruptedException();
758	+	int es = status;
759	+	if (es != NORMAL) {
760	+	Throwable ex;
761	+	if (es == CANCELLED)
762	+	throw new CancellationException();
763	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
764	+	throw new ExecutionException(ex);
765	+	throw new TimeoutException();
766	+	}
767	+	return getRawResult();
768		}
769
770		/**
771	<	* Joins this task, without returning its result or throwing an
771	>	* Joins this task, without returning its result or throwing its
772		* exception. This method may be useful when processing
773		* collections of tasks when some have been cancelled or otherwise
774		* known to have aborted.
775		*/
776		public final void quietlyJoin() {
777	<	Thread t = Thread.currentThread();
778	<	if (t instanceof ForkJoinWorkerThread) {
777	>	Thread t;
778	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
779		ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
780	<	if (!w.unpushTask(this) || !tryExec())
781	<	awaitDone(w);
780	>	if (status >= 0) {
781	>	if (w.unpushTask(this)) {
782	>	boolean completed;
783	>	try {
784	>	completed = exec();
785	>	} catch (Throwable rex) {
786	>	setExceptionalCompletion(rex);
787	>	return;
788	>	}
789	>	if (completed) {
790	>	setCompletion(NORMAL);
791	>	return;
792	>	}
793	>	}
794	>	w.joinTask(this);
795	>	}
796		}
797		else
798		externalAwaitDone();
#	Line 863 | Line 800 | public abstract class ForkJoinTask<V> im
800
801		/**
802		* Commences performing this task and awaits its completion if
803	<	* necessary, without returning its result or throwing an
804	<	* exception. This method may be useful when processing
868	<	* collections of tasks when some have been cancelled or otherwise
869	<	* known to have aborted.
803	>	* necessary, without returning its result or throwing its
804	>	* exception.
805		*/
806		public final void quietlyInvoke() {
807	<	if (!tryExec())
808	<	quietlyJoin();
807	>	if (status >= 0) {
808	>	boolean completed;
809	>	try {
810	>	completed = exec();
811	>	} catch (Throwable rex) {
812	>	setExceptionalCompletion(rex);
813	>	return;
814	>	}
815	>	if (completed)
816	>	setCompletion(NORMAL);
817	>	else
818	>	quietlyJoin();
819	>	}
820		}
821
822		/**
#	Line 902 | Line 848 | public abstract class ForkJoinTask<V> im
848		* pre-constructed trees of subtasks in loops.
849		*/
850		public void reinitialize() {
851	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
851	>	if (status == EXCEPTIONAL)
852		exceptionMap.remove(this);
853		status = 0;
854		}
#	Line 1192 | Line 1138 | public abstract class ForkJoinTask<V> im
1138		private static final long serialVersionUID = -7721805057305804111L;
1139
1140		/**
1141	<	* Saves the state to a stream.
1141	>	* Saves the state to a stream (that is, serializes it).
1142		*
1143		* @serialData the current run status and the exception thrown
1144		* during execution, or {@code null} if none
#	Line 1205 | Line 1151 | public abstract class ForkJoinTask<V> im
1151		}
1152
1153		/**
1154	<	* Reconstitutes the instance from a stream.
1154	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1155		*
1156		* @param s the stream
1157		*/
1158		private void readObject(java.io.ObjectInputStream s)
1159		throws java.io.IOException, ClassNotFoundException {
1160		s.defaultReadObject();
1215	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1216	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1161		Object ex = s.readObject();
1162		if (ex != null)
1163	<	setDoneExceptionally((Throwable) ex);
1163	>	setExceptionalCompletion((Throwable) ex);
1164		}
1165
1166		// Unsafe mechanics

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