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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.47 by dl, Sun Apr 18 12:51:18 2010 UTC vs.
Revision 1.59 by jsr166, Tue Sep 7 07:51:13 2010 UTC

#	Line 64 | Line 64 | import java.util.WeakHashMap;
64		* results of a task is {@link #join}, but there are several variants:
65		* The {@link Future#get} methods support interruptible and/or timed
66		* waits for completion and report results using {@code Future}
67	<	* 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
67	>	* conventions. Method {@link #invoke} is semantically
68		* equivalent to {@code fork(); join()} but always attempts to begin
69		* execution in the current thread. The "<em>quiet</em>" forms of
70		* these methods do not extract results or report exceptions. These
#	Line 103 | Line 100 | import java.util.WeakHashMap;
100		* ForkJoinTasks (as may be determined using method {@link
101		* #inForkJoinPool}).  Attempts to invoke them in other contexts
102		* result in exceptions or errors, possibly including
103	<	* ClassCastException.
103	>	* {@code ClassCastException}.
104		*
105		* <p>Most base support methods are {@code final}, to prevent
106		* overriding of implementations that are intrinsically tied to the
#	Line 125 | Line 122 | import java.util.WeakHashMap;
122		*
123		* <p>This class provides {@code adapt} methods for {@link Runnable}
124		* and {@link Callable}, that may be of use when mixing execution of
125	<	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
126	<	* are of this form, consider using a pool in
130	<	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
125	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
126	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
127		*
128		* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
129		* used in extensions such as remote execution frameworks. It is
#	Line 148 | Line 144 | public abstract class ForkJoinTask<V> im
144		* status maintenance (2) execution and awaiting completion (3)
145		* user-level methods that additionally report results. This is
146		* sometimes hard to see because this file orders exported methods
147	<	* in a way that flows well in javadocs.
147	>	* in a way that flows well in javadocs. In particular, most
148	>	* join mechanics are in method quietlyJoin, below.
149		*/
150
151	<	/**
152	<	* Run control status bits packed into a single int to minimize
153	<	* footprint and to ensure atomicity (via CAS).  Status is
154	<	* initially zero, and takes on nonnegative values until
155	<	* completed, upon which status holds COMPLETED. CANCELLED, or
156	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
157	<	* blocking waits by other threads have SIGNAL_MASK bits set --
158	<	* bit 15 for external (nonFJ) waits, and the rest a count of
159	<	* waiting FJ threads.  (This representation relies on
160	<	* ForkJoinPool max thread limits). Signal counts are not directly
161	<	* incremented by ForkJoinTask methods, but instead via a call to
162	<	* requestSignal within ForkJoinPool.preJoin, once their need is
163	<	* established.
164	<	*
165	<	* 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.
151	>	/*
152	>	* The status field holds run control status bits packed into a
153	>	* single int to minimize footprint and to ensure atomicity (via
154	>	* CAS).  Status is initially zero, and takes on nonnegative
155	>	* values until completed, upon which status holds value
156	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
157	>	* waits by other threads have the SIGNAL bit set.  Completion of
158	>	* a stolen task with SIGNAL set awakens any waiters via
159	>	* notifyAll. Even though suboptimal for some purposes, we use
160	>	* basic builtin wait/notify to take advantage of "monitor
161	>	* inflation" in JVMs that we would otherwise need to emulate to
162	>	* avoid adding further per-task bookkeeping overhead.  We want
163	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
164	>	* techniques, so use some odd coding idioms that tend to avoid
165	>	* them.
166		*/
167	+
168	+	/** The run status of this task */
169		volatile int status; // accessed directly by pool and workers
170
171	<	private static final int COMPLETION_MASK      = 0xe0000000;
172	<	private static final int NORMAL               = 0xe0000000; // == mask
173	<	private static final int CANCELLED            = 0xc0000000;
174	<	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;
171	>	private static final int NORMAL      = -1;
172	>	private static final int CANCELLED   = -2;
173	>	private static final int EXCEPTIONAL = -3;
174	>	private static final int SIGNAL      =  1;
175
176		/**
177		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 211 | Line 197 | public abstract class ForkJoinTask<V> im
197		int s;
198		while ((s = status) >= 0) {
199		if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
200	<	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);
200	>	if (s != 0)
201		synchronized (this) { notifyAll(); }
202	<	}
221	<	return;
202	>	break;
203		}
204		}
205		}
206
207		/**
208	<	* Record exception and set exceptional completion
208	>	* Records exception and sets exceptional completion.
209	>	*
210	>	* @return status on exit
211		*/
212	<	private void setDoneExceptionally(Throwable rex) {
212	>	private void setExceptionalCompletion(Throwable rex) {
213		exceptionMap.put(this, rex);
214		setCompletion(EXCEPTIONAL);
215		}
216
217		/**
218	<	* Main internal execution method: Unless done, calls exec and
219	<	* records completion.
220	<	*
238	<	* @return true if ran and completed normally
218	>	* Blocks a worker thread until completion. Called only by
219	>	* pool. Currently unused -- pool-based waits use timeout
220	>	* version below.
221		*/
222	<	final boolean tryExec() {
223	<	try {
224	<	if (status < 0 || !exec())
225	<	return false;
226	<	} catch (Throwable rex) {
227	<	setDoneExceptionally(rex);
228	<	return false;
222	>	final void internalAwaitDone() {
223	>	int s;         // the odd construction reduces lock bias effects
224	>	while ((s = status) >= 0) {
225	>	try {
226	>	synchronized(this) {
227	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
228	>	wait();
229	>	}
230	>	} catch (InterruptedException ie) {
231	>	cancelIfTerminating();
232	>	}
233		}
248	–	setCompletion(NORMAL); // must be outside try block
249	–	return true;
234		}
235
236		/**
237	<	* Increments internal signal count (thus requesting signal upon
238	<	* completion) unless already done.  Call only once per join.
255	<	* Used by ForkJoinPool.preJoin.
237	>	* Blocks a worker thread until completed or timed out.  Called
238	>	* only by pool.
239		*
240	<	* @return status
240	>	* @return status on exit
241		*/
242	<	final int requestSignal() {
242	>	final int internalAwaitDone(long millis) {
243		int s;
244	<	do {} while ((s = status) >= 0 &&
245	<	!UNSAFE.compareAndSwapInt(this, statusOffset, s, s + 1));
246	<	return s;
247	<	}
248	<
266	<	/**
267	<	* Sets external signal request unless already done.
268	<	*
269	<	* @return status
270	<	*/
271	<	private int requestExternalSignal() {
272	<	int s;
273	<	do {} while ((s = status) >= 0 &&
274	<	!UNSAFE.compareAndSwapInt(this, statusOffset,
275	<	s, s | EXTERNAL_SIGNAL));
276	<	return s;
277	<	}
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();
244	>	if ((s = status) >= 0) {
245	>	try {
246	>	synchronized(this) {
247	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
248	>	wait(millis, 0);
249		}
250	+	} catch (InterruptedException ie) {
251	+	cancelIfTerminating();
252		}
253	+	s = status;
254		}
255	+	return s;
256		}
257
258		/**
259	<	* Blocks a non-ForkJoin thread until this task is done.
259	>	* Blocks a non-worker-thread until completion.
260		*/
261		private void externalAwaitDone() {
262	<	if (requestExternalSignal() >= 0) {
263	<	boolean interrupted = false;
264	<	while (status >= 0) {
265	<	try {
266	<	synchronized(this) {
267	<	if (status >= 0)
262	>	int s;
263	>	while ((s = status) >= 0) {
264	>	synchronized(this) {
265	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
266	>	boolean interrupted = false;
267	>	while (status >= 0) {
268	>	try {
269		wait();
270	<	else {
271	<	notifyAll();
322	<	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;
270	>	} catch (InterruptedException ie) {
271	>	interrupted = true;
272		}
273		}
274	+	if (interrupted)
275	+	Thread.currentThread().interrupt();
276		break;
277		}
278		}
#	Line 367 | Line 280 | public abstract class ForkJoinTask<V> im
280		}
281
282		/**
283	<	* Blocks a non-ForkJoin thread until this task is done or timeout elapses
284	<	*/
285	<	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.
399	<	*/
400	<	private V reportResult() {
401	<	if ((status & COMPLETION_MASK) < NORMAL) {
402	<	Throwable ex = getException();
403	<	if (ex != null)
404	<	UNSAFE.throwException(ex);
405	<	}
406	<	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.
283	>	* Unless done, calls exec and records status if completed, but
284	>	* doesn't wait for completion otherwise. Primary execution method
285	>	* for ForkJoinWorkerThread.
286		*/
287	<	private V reportFutureResult()
288	<	throws InterruptedException, ExecutionException {
289	<	if (Thread.interrupted())
290	<	throw new InterruptedException();
291	<	int s = status & COMPLETION_MASK;
292	<	if (s < NORMAL) {
293	<	Throwable ex;
421	<	if (s == CANCELLED)
422	<	throw new CancellationException();
423	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
424	<	throw new ExecutionException(ex);
287	>	final void quietlyExec() {
288	>	try {
289	>	if (status < 0 || !exec())
290	>	return;
291	>	} catch (Throwable rex) {
292	>	setExceptionalCompletion(rex);
293	>	return;
294		}
295	<	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();
295	>	setCompletion(NORMAL); // must be outside try block
296		}
297
298		// public methods
#	Line 482 | Line 331 | public abstract class ForkJoinTask<V> im
331		*/
332		public final V join() {
333		quietlyJoin();
334	<	return reportResult();
334	>	Throwable ex;
335	>	if (status < NORMAL && (ex = getException()) != null)
336	>	UNSAFE.throwException(ex);
337	>	return getRawResult();
338		}
339
340		/**
341		* Commences performing this task, awaits its completion if
342	<	* necessary, and return its result, or throws an (unchecked)
343	<	* exception if the underlying computation did so.
342	>	* necessary, and returns its result, or throws an (unchecked)
343	>	* {@code RuntimeException} or {@code Error} if the underlying
344	>	* computation did so.
345		*
346		* @return the computed result
347		*/
348		public final V invoke() {
349	<	if (!tryExec())
350	<	quietlyJoin();
351	<	return reportResult();
349	>	quietlyInvoke();
350	>	Throwable ex;
351	>	if (status < NORMAL && (ex = getException()) != null)
352	>	UNSAFE.throwException(ex);
353	>	return getRawResult();
354		}
355
356		/**
357		* Forks the given tasks, returning when {@code isDone} holds for
358		* each task or an (unchecked) exception is encountered, in which
359	<	* case the exception is rethrown.  If either task encounters an
360	<	* exception, the other one may be, but is not guaranteed to be,
361	<	* cancelled.  If both tasks throw an exception, then this method
362	<	* throws one of them.  The individual status of each task may be
363	<	* checked using {@link #getException()} and related methods.
359	>	* case the exception is rethrown. If more than one task
360	>	* encounters an exception, then this method throws any one of
361	>	* these exceptions. If any task encounters an exception, the
362	>	* other may be cancelled. However, the execution status of
363	>	* individual tasks is not guaranteed upon exceptional return. The
364	>	* status of each task may be obtained using {@link
365	>	* #getException()} and related methods to check if they have been
366	>	* cancelled, completed normally or exceptionally, or left
367	>	* unprocessed.
368		*
369		* <p>This method may be invoked only from within {@code
370		* ForkJoinTask} computations (as may be determined using method
#	Line 526 | Line 385 | public abstract class ForkJoinTask<V> im
385		/**
386		* Forks the given tasks, returning when {@code isDone} holds for
387		* each task or an (unchecked) exception is encountered, in which
388	<	* case the exception is rethrown. If any task encounters an
389	<	* exception, others may be, but are not guaranteed to be,
390	<	* cancelled.  If more than one task encounters an exception, then
391	<	* this method throws any one of these exceptions.  The individual
392	<	* status of each task may be checked using {@link #getException()}
393	<	* and related methods.
388	>	* case the exception is rethrown. If more than one task
389	>	* encounters an exception, then this method throws any one of
390	>	* these exceptions. If any task encounters an exception, others
391	>	* may be cancelled. However, the execution status of individual
392	>	* tasks is not guaranteed upon exceptional return. The status of
393	>	* each task may be obtained using {@link #getException()} and
394	>	* related methods to check if they have been cancelled, completed
395	>	* normally or exceptionally, or left unprocessed.
396		*
397		* <p>This method may be invoked only from within {@code
398		* ForkJoinTask} computations (as may be determined using method
#	Line 555 | Line 416 | public abstract class ForkJoinTask<V> im
416		t.fork();
417		else {
418		t.quietlyInvoke();
419	<	if (ex == null)
419	>	if (ex == null && t.status < NORMAL)
420		ex = t.getException();
421		}
422		}
#	Line 566 | Line 427 | public abstract class ForkJoinTask<V> im
427		t.cancel(false);
428		else {
429		t.quietlyJoin();
430	<	if (ex == null)
430	>	if (ex == null && t.status < NORMAL)
431		ex = t.getException();
432		}
433		}
#	Line 578 | Line 439 | public abstract class ForkJoinTask<V> im
439		/**
440		* Forks all tasks in the specified collection, returning when
441		* {@code isDone} holds for each task or an (unchecked) exception
442	<	* is encountered.  If any task encounters an exception, others
443	<	* may be, but are not guaranteed to be, cancelled.  If more than
444	<	* one task encounters an exception, then this method throws any
445	<	* one of these exceptions.  The individual status of each task
446	<	* may be checked using {@link #getException()} and related
447	<	* methods.  The behavior of this operation is undefined if the
448	<	* specified collection is modified while the operation is in
449	<	* progress.
442	>	* is encountered, in which case the exception is rethrown. If
443	>	* more than one task encounters an exception, then this method
444	>	* throws any one of these exceptions. If any task encounters an
445	>	* exception, others may be cancelled. However, the execution
446	>	* status of individual tasks is not guaranteed upon exceptional
447	>	* return. The status of each task may be obtained using {@link
448	>	* #getException()} and related methods to check if they have been
449	>	* cancelled, completed normally or exceptionally, or left
450	>	* unprocessed.
451		*
452		* <p>This method may be invoked only from within {@code
453		* ForkJoinTask} computations (as may be determined using method
#	Line 617 | Line 479 | public abstract class ForkJoinTask<V> im
479		t.fork();
480		else {
481		t.quietlyInvoke();
482	<	if (ex == null)
482	>	if (ex == null && t.status < NORMAL)
483		ex = t.getException();
484		}
485		}
#	Line 628 | Line 490 | public abstract class ForkJoinTask<V> im
490		t.cancel(false);
491		else {
492		t.quietlyJoin();
493	<	if (ex == null)
493	>	if (ex == null && t.status < NORMAL)
494		ex = t.getException();
495		}
496		}
#	Line 664 | Line 526 | public abstract class ForkJoinTask<V> im
526		*/
527		public boolean cancel(boolean mayInterruptIfRunning) {
528		setCompletion(CANCELLED);
529	<	return (status & COMPLETION_MASK) == CANCELLED;
529	>	return status == CANCELLED;
530		}
531
532		/**
533	<	* Cancels, ignoring any exceptions it throws. Used during worker
534	<	* and pool shutdown.
533	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
534	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
535	>	* exceptions, but if it does anyway, we have no recourse during
536	>	* shutdown, so guard against this case.
537		*/
538		final void cancelIgnoringExceptions() {
539		try {
#	Line 679 | Line 543 | public abstract class ForkJoinTask<V> im
543		}
544
545		/**
546	<	* Cancels ignoring exceptions if worker is terminating
546	>	* Cancels if current thread is a terminating worker thread,
547	>	* ignoring any exceptions thrown by cancel.
548		*/
549	<	private void cancelIfTerminating() {
549	>	final void cancelIfTerminating() {
550		Thread t = Thread.currentThread();
551		if ((t instanceof ForkJoinWorkerThread) &&
552		((ForkJoinWorkerThread) t).isTerminating()) {
#	Line 697 | Line 562 | public abstract class ForkJoinTask<V> im
562		}
563
564		public final boolean isCancelled() {
565	<	return (status & COMPLETION_MASK) == CANCELLED;
565	>	return status == CANCELLED;
566		}
567
568		/**
#	Line 706 | Line 571 | public abstract class ForkJoinTask<V> im
571		* @return {@code true} if this task threw an exception or was cancelled
572		*/
573		public final boolean isCompletedAbnormally() {
574	<	return (status & COMPLETION_MASK) < NORMAL;
574	>	return status < NORMAL;
575		}
576
577		/**
#	Line 717 | Line 582 | public abstract class ForkJoinTask<V> im
582		* exception and was not cancelled
583		*/
584		public final boolean isCompletedNormally() {
585	<	return (status & COMPLETION_MASK) == NORMAL;
585	>	return status == NORMAL;
586		}
587
588		/**
#	Line 728 | Line 593 | public abstract class ForkJoinTask<V> im
593		* @return the exception, or {@code null} if none
594		*/
595		public final Throwable getException() {
596	<	int s = status & COMPLETION_MASK;
596	>	int s = status;
597		return ((s >= NORMAL)    ? null :
598		(s == CANCELLED) ? new CancellationException() :
599		exceptionMap.get(this));
#	Line 749 | Line 614 | public abstract class ForkJoinTask<V> im
614		* thrown will be a {@code RuntimeException} with cause {@code ex}.
615		*/
616		public void completeExceptionally(Throwable ex) {
617	<	setDoneExceptionally((ex instanceof RuntimeException) ||
618	<	(ex instanceof Error) ? ex :
619	<	new RuntimeException(ex));
617	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
618	>	(ex instanceof Error) ? ex :
619	>	new RuntimeException(ex));
620		}
621
622		/**
623		* Completes this task, and if not already aborted or cancelled,
624	<	* returning a {@code null} result upon {@code join} and related
625	<	* operations. This method may be used to provide results for
626	<	* asynchronous tasks, or to provide alternative handling for
627	<	* tasks that would not otherwise complete normally. Its use in
628	<	* other situations is discouraged. This method is
629	<	* overridable, but overridden versions must invoke {@code super}
630	<	* implementation to maintain guarantees.
624	>	* returning the given value as the result of subsequent
625	>	* invocations of {@code join} and related operations. This method
626	>	* may be used to provide results for asynchronous tasks, or to
627	>	* provide alternative handling for tasks that would not otherwise
628	>	* complete normally. Its use in other situations is
629	>	* discouraged. This method is overridable, but overridden
630	>	* versions must invoke {@code super} implementation to maintain
631	>	* guarantees.
632		*
633		* @param value the result value for this task
634		*/
#	Line 770 | Line 636 | public abstract class ForkJoinTask<V> im
636		try {
637		setRawResult(value);
638		} catch (Throwable rex) {
639	<	setDoneExceptionally(rex);
639	>	setExceptionalCompletion(rex);
640		return;
641		}
642		setCompletion(NORMAL);
#	Line 778 | Line 644 | public abstract class ForkJoinTask<V> im
644
645		public final V get() throws InterruptedException, ExecutionException {
646		quietlyJoin();
647	<	return reportFutureResult();
647	>	if (Thread.interrupted())
648	>	throw new InterruptedException();
649	>	int s = status;
650	>	if (s < NORMAL) {
651	>	Throwable ex;
652	>	if (s == CANCELLED)
653	>	throw new CancellationException();
654	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
655	>	throw new ExecutionException(ex);
656	>	}
657	>	return getRawResult();
658		}
659
660		public final V get(long timeout, TimeUnit unit)
661		throws InterruptedException, ExecutionException, TimeoutException {
786	–	long nanos = unit.toNanos(timeout);
662		Thread t = Thread.currentThread();
663	+	ForkJoinPool pool;
664		if (t instanceof ForkJoinWorkerThread) {
665		ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
666	<	if (!w.unpushTask(this) || !tryExec())
667	<	timedAwaitDone(w, nanos);
666	>	if (status >= 0 && w.unpushTask(this))
667	>	quietlyExec();
668	>	pool = w.pool;
669		}
670		else
671	<	externalTimedAwaitDone(nanos);
672	<	return reportTimedFutureResult();
673	<	}
674	<
675	<	/**
676	<	* Possibly executes other tasks until this task {@link #isDone is
677	<	* done}, then returns the result of the computation.  This method
678	<	* may be more efficient than {@code join}, but is only applicable
679	<	* when there are no potential dependencies between continuation
680	<	* of the current task and that of any other task that might be
681	<	* executed while helping. (This usually holds for pure
682	<	* divide-and-conquer tasks).
683	<	*
684	<	* <p>This method may be invoked only from within {@code
685	<	* ForkJoinTask} computations (as may be determined using method
686	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
687	<	* result in exceptions or errors, possibly including {@code
688	<	* ClassCastException}.
689	<	*
690	<	* @return the computed result
691	<	*/
692	<	public final V helpJoin() {
693	<	quietlyHelpJoin();
694	<	return reportResult();
695	<	}
696	<
697	<	/**
698	<	* Possibly executes other tasks until this task {@link #isDone is
699	<	* done}.  This method may be useful when processing collections
823	<	* of tasks when some have been cancelled or otherwise known to
824	<	* have aborted.
825	<	*
826	<	* <p>This method may be invoked only from within {@code
827	<	* ForkJoinTask} computations (as may be determined using method
828	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
829	<	* result in exceptions or errors, possibly including {@code
830	<	* ClassCastException}.
831	<	*/
832	<	public final void quietlyHelpJoin() {
833	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
834	<	if (!w.unpushTask(this) || !tryExec()) {
835	<	for (;;) {
836	<	ForkJoinTask<?> t;
837	<	if (status < 0)
838	<	return;
839	<	else if ((t = w.scanWhileJoining(this)) != null)
840	<	t.tryExec();
841	<	else if (status < 0)
842	<	return;
843	<	else if (w.pool.preBlockHelpingJoin(this)) {
844	<	while (status >= 0) { // variant of awaitDone
671	>	pool = null;
672	>	/*
673	>	* Timed wait loop intermixes cases for FJ (pool != null) and
674	>	* non FJ threads. For FJ, decrement pool count but don't try
675	>	* for replacement; increment count on completion. For non-FJ,
676	>	* deal with interrupts. This is messy, but a little less so
677	>	* than is splitting the FJ and nonFJ cases.
678	>	*/
679	>	boolean interrupted = false;
680	>	boolean dec = false; // true if pool count decremented
681	>	long nanos = unit.toNanos(timeout);
682	>	for (;;) {
683	>	if (pool == null && Thread.interrupted()) {
684	>	interrupted = true;
685	>	break;
686	>	}
687	>	int s = status;
688	>	if (s < 0)
689	>	break;
690	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
691	>	long startTime = System.nanoTime();
692	>	long nt; // wait time
693	>	while (status >= 0 &&
694	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
695	>	if (pool != null && !dec)
696	>	dec = pool.tryDecrementRunningCount();
697	>	else {
698	>	long ms = nt / 1000000;
699	>	int ns = (int) (nt % 1000000);
700		try {
701		synchronized(this) {
702		if (status >= 0)
703	<	wait();
849	<	else {
850	<	notifyAll();
851	<	break;
852	<	}
703	>	wait(ms, ns);
704		}
705		} catch (InterruptedException ie) {
706	<	cancelIfTerminating();
706	>	if (pool != null)
707	>	cancelIfTerminating();
708	>	else {
709	>	interrupted = true;
710	>	break;
711	>	}
712		}
713		}
858	–	return;
714		}
715	+	break;
716		}
717		}
718	+	if (pool != null && dec)
719	+	pool.incrementRunningCount();
720	+	if (interrupted)
721	+	throw new InterruptedException();
722	+	int es = status;
723	+	if (es != NORMAL) {
724	+	Throwable ex;
725	+	if (es == CANCELLED)
726	+	throw new CancellationException();
727	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
728	+	throw new ExecutionException(ex);
729	+	throw new TimeoutException();
730	+	}
731	+	return getRawResult();
732		}
733
734		/**
735	<	* Joins this task, without returning its result or throwing an
735	>	* Joins this task, without returning its result or throwing its
736		* exception. This method may be useful when processing
737		* collections of tasks when some have been cancelled or otherwise
738		* known to have aborted.
739		*/
740		public final void quietlyJoin() {
741	<	Thread t = Thread.currentThread();
742	<	if (t instanceof ForkJoinWorkerThread) {
741	>	Thread t;
742	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
743		ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
744	<	if (!w.unpushTask(this) || !tryExec())
745	<	awaitDone(w);
744	>	if (status >= 0) {
745	>	if (w.unpushTask(this)) {
746	>	boolean completed;
747	>	try {
748	>	completed = exec();
749	>	} catch (Throwable rex) {
750	>	setExceptionalCompletion(rex);
751	>	return;
752	>	}
753	>	if (completed) {
754	>	setCompletion(NORMAL);
755	>	return;
756	>	}
757	>	}
758	>	w.joinTask(this);
759	>	}
760		}
761		else
762		externalAwaitDone();
#	Line 880 | Line 764 | public abstract class ForkJoinTask<V> im
764
765		/**
766		* Commences performing this task and awaits its completion if
767	<	* necessary, without returning its result or throwing an
768	<	* exception. This method may be useful when processing
885	<	* collections of tasks when some have been cancelled or otherwise
886	<	* known to have aborted.
767	>	* necessary, without returning its result or throwing its
768	>	* exception.
769		*/
770		public final void quietlyInvoke() {
771	<	if (!tryExec())
772	<	quietlyJoin();
771	>	if (status >= 0) {
772	>	boolean completed;
773	>	try {
774	>	completed = exec();
775	>	} catch (Throwable rex) {
776	>	setExceptionalCompletion(rex);
777	>	return;
778	>	}
779	>	if (completed)
780	>	setCompletion(NORMAL);
781	>	else
782	>	quietlyJoin();
783	>	}
784		}
785
786		/**
#	Line 919 | Line 812 | public abstract class ForkJoinTask<V> im
812		* pre-constructed trees of subtasks in loops.
813		*/
814		public void reinitialize() {
815	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
815	>	if (status == EXCEPTIONAL)
816		exceptionMap.remove(this);
817		status = 0;
818		}
#	Line 1209 | Line 1102 | public abstract class ForkJoinTask<V> im
1102		private static final long serialVersionUID = -7721805057305804111L;
1103
1104		/**
1105	<	* Saves the state to a stream.
1105	>	* Saves the state to a stream (that is, serializes it).
1106		*
1107		* @serialData the current run status and the exception thrown
1108		* during execution, or {@code null} if none
#	Line 1222 | Line 1115 | public abstract class ForkJoinTask<V> im
1115		}
1116
1117		/**
1118	<	* Reconstitutes the instance from a stream.
1118	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1119		*
1120		* @param s the stream
1121		*/
1122		private void readObject(java.io.ObjectInputStream s)
1123		throws java.io.IOException, ClassNotFoundException {
1124		s.defaultReadObject();
1232	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1233	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1125		Object ex = s.readObject();
1126		if (ex != null)
1127	<	setDoneExceptionally((Throwable) ex);
1127	>	setExceptionalCompletion((Throwable) ex);
1128		}
1129
1130		// Unsafe mechanics

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