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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.50 by dl, Fri Jul 23 13:07:43 2010 UTC vs.
Revision 1.56 by jsr166, Sat Sep 4 00:21:31 2010 UTC

#	Line 144 | 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		/*
#	Line 164 | Line 165 | public abstract class ForkJoinTask<V> im
165		* them.
166		*/
167
168	<	/** Run status of this task */
168	>	/** The run status of this task */
169		volatile int status; // accessed directly by pool and workers
170
171		private static final int NORMAL      = -1;
#	Line 191 | Line 192 | public abstract class ForkJoinTask<V> im
192		* also clearing signal request bits.
193		*
194		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
194	–	* @return status on exit
195		*/
196	<	private int setCompletion(int completion) {
196	>	private void setCompletion(int completion) {
197		int s;
198		while ((s = status) >= 0) {
199		if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
200	<	if (s == SIGNAL)
200	>	if (s != 0)
201		synchronized (this) { notifyAll(); }
202	<	return completion;
202	>	break;
203		}
204		}
205	–	return s;
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 int setExceptionalCompletion(Throwable rex) {
212	>	private void setExceptionalCompletion(Throwable rex) {
213		exceptionMap.put(this, rex);
214	<	return setCompletion(EXCEPTIONAL);
214	>	setCompletion(EXCEPTIONAL);
215		}
216
217		/**
218	<	* Blocks a worker thread until completion. Called only by pool.
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 void internalAwaitDone() {
223		int s;         // the odd construction reduces lock bias effects
#	Line 232 | Line 234 | public abstract class ForkJoinTask<V> im
234		}
235
236		/**
237	<	* Blocks a non-worker-thread until completion.
237	>	* Blocks a worker thread until completed or timed out.  Called
238	>	* only by pool.
239	>	*
240		* @return status on exit
241		*/
242	<	private int externalAwaitDone() {
242	>	final int internalAwaitDone(long millis) {
243	>	int s;
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-worker-thread until completion.
260	>	*/
261	>	private void externalAwaitDone() {
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 ((s = status) >= 0) {
267	>	while (status >= 0) {
268		try {
269		wait();
270		} catch (InterruptedException ie) {
#	Line 254 | Line 277 | public abstract class ForkJoinTask<V> im
277		}
278		}
279		}
257	–	return s;
280		}
281
282		/**
#	Line 262 | Line 284 | public abstract class ForkJoinTask<V> im
284		* doesn't wait for completion otherwise. Primary execution method
285		* for ForkJoinWorkerThread.
286		*/
287	<	final void tryExec() {
287	>	final void quietlyExec() {
288		try {
289		if (status < 0 || !exec())
290		return;
#	Line 273 | Line 295 | public abstract class ForkJoinTask<V> im
295		setCompletion(NORMAL); // must be outside try block
296		}
297
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	–	if ((stat = status) < 0)
284	–	return stat;
285	–	Thread t = Thread.currentThread();
286	–	ForkJoinWorkerThread w;
287	–	if (t instanceof ForkJoinWorkerThread) {
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	–
298		// public methods
299
300		/**
#	Line 365 | Line 330 | public abstract class ForkJoinTask<V> im
330		* @return the computed result
331		*/
332		public final V join() {
333	<	return reportResult(doJoin());
333	>	quietlyJoin();
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)
342	>	* necessary, and returns its result, or throws an (unchecked)
343		* exception if the underlying computation did so.
344		*
345		* @return the computed result
346		*/
347		public final V invoke() {
348	<	return reportResult(doInvoke());
348	>	quietlyInvoke();
349	>	Throwable ex;
350	>	if (status < NORMAL && (ex = getException()) != null)
351	>	UNSAFE.throwException(ex);
352	>	return getRawResult();
353		}
354
355		/**
#	Line 434 | Line 407 | public abstract class ForkJoinTask<V> im
407		}
408		else if (i != 0)
409		t.fork();
410	<	else if (t.doInvoke() < NORMAL && ex == null)
411	<	ex = t.getException();
410	>	else {
411	>	t.quietlyInvoke();
412	>	if (ex == null && t.status < NORMAL)
413	>	ex = t.getException();
414	>	}
415		}
416		for (int i = 1; i <= last; ++i) {
417		ForkJoinTask<?> t = tasks[i];
418		if (t != null) {
419		if (ex != null)
420		t.cancel(false);
421	<	else if (t.doJoin() < NORMAL && ex == null)
422	<	ex = t.getException();
421	>	else {
422	>	t.quietlyJoin();
423	>	if (ex == null && t.status < NORMAL)
424	>	ex = t.getException();
425	>	}
426		}
427		}
428		if (ex != null)
#	Line 490 | Line 469 | public abstract class ForkJoinTask<V> im
469		}
470		else if (i != 0)
471		t.fork();
472	<	else if (t.doInvoke() < NORMAL && ex == null)
473	<	ex = t.getException();
472	>	else {
473	>	t.quietlyInvoke();
474	>	if (ex == null && t.status < NORMAL)
475	>	ex = t.getException();
476	>	}
477		}
478		for (int i = 1; i <= last; ++i) {
479		ForkJoinTask<?> t = ts.get(i);
480		if (t != null) {
481		if (ex != null)
482		t.cancel(false);
483	<	else if (t.doJoin() < NORMAL && ex == null)
484	<	ex = t.getException();
483	>	else {
484	>	t.quietlyJoin();
485	>	if (ex == null && t.status < NORMAL)
486	>	ex = t.getException();
487	>	}
488		}
489		}
490		if (ex != null)
#	Line 532 | Line 517 | public abstract class ForkJoinTask<V> im
517		* @return {@code true} if this task is now cancelled
518		*/
519		public boolean cancel(boolean mayInterruptIfRunning) {
520	<	return setCompletion(CANCELLED) == CANCELLED;
520	>	setCompletion(CANCELLED);
521	>	return status == CANCELLED;
522		}
523
524		/**
525	<	* Cancels, ignoring any exceptions it throws. Used during worker
526	<	* and pool shutdown.
525	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
526	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
527	>	* exceptions, but if it does anyway, we have no recourse during
528	>	* shutdown, so guard against this case.
529		*/
530		final void cancelIgnoringExceptions() {
531		try {
#	Line 547 | Line 535 | public abstract class ForkJoinTask<V> im
535		}
536
537		/**
538	<	* Cancels ignoring exceptions if worker is terminating
538	>	* Cancels if current thread is a terminating worker thread,
539	>	* ignoring any exceptions thrown by cancel.
540		*/
541		final void cancelIfTerminating() {
542		Thread t = Thread.currentThread();
#	Line 645 | Line 634 | public abstract class ForkJoinTask<V> im
634		}
635
636		public final V get() throws InterruptedException, ExecutionException {
637	<	int s = doJoin();
637	>	quietlyJoin();
638		if (Thread.interrupted())
639		throw new InterruptedException();
640	+	int s = status;
641		if (s < NORMAL) {
642		Throwable ex;
643		if (s == CANCELLED)
#	Line 665 | Line 655 | public abstract class ForkJoinTask<V> im
655		if (t instanceof ForkJoinWorkerThread) {
656		ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
657		if (status >= 0 && w.unpushTask(this))
658	<	tryExec();
658	>	quietlyExec();
659		pool = w.pool;
660		}
661		else
662		pool = null;
663		/*
664	<	* Timed wait loop intermixes cases for fj (pool != null) and
664	>	* Timed wait loop intermixes cases for FJ (pool != null) and
665		* non FJ threads. For FJ, decrement pool count but don't try
666		* for replacement; increment count on completion. For non-FJ,
667		* deal with interrupts. This is messy, but a little less so
#	Line 679 | Line 669 | public abstract class ForkJoinTask<V> im
669		*/
670		boolean interrupted = false;
671		boolean dec = false; // true if pool count decremented
672	+	long nanos = unit.toNanos(timeout);
673		for (;;) {
674		if (Thread.interrupted() && pool == null) {
675		interrupted = true;
#	Line 687 | Line 678 | public abstract class ForkJoinTask<V> im
678		int s = status;
679		if (s < 0)
680		break;
681	<	if (UNSAFE.compareAndSwapInt(this, statusOffset,
691	<	s, s | SIGNAL)) {
681	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
682		long startTime = System.nanoTime();
693	–	long nanos = unit.toNanos(timeout);
683		long nt; // wait time
684		while (status >= 0 &&
685		(nt = nanos - (System.nanoTime() - startTime)) > 0) {
#	Line 734 | Line 723 | public abstract class ForkJoinTask<V> im
723		}
724
725		/**
726	<	* Joins this task, without returning its result or throwing an
726	>	* Joins this task, without returning its result or throwing its
727		* exception. This method may be useful when processing
728		* collections of tasks when some have been cancelled or otherwise
729		* known to have aborted.
730		*/
731		public final void quietlyJoin() {
732	<	doJoin();
732	>	Thread t;
733	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
734	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
735	>	if (status >= 0) {
736	>	if (w.unpushTask(this)) {
737	>	boolean completed;
738	>	try {
739	>	completed = exec();
740	>	} catch (Throwable rex) {
741	>	setExceptionalCompletion(rex);
742	>	return;
743	>	}
744	>	if (completed) {
745	>	setCompletion(NORMAL);
746	>	return;
747	>	}
748	>	}
749	>	w.joinTask(this);
750	>	}
751	>	}
752	>	else
753	>	externalAwaitDone();
754		}
755
756		/**
757		* Commences performing this task and awaits its completion if
758	<	* necessary, without returning its result or throwing an
758	>	* necessary, without returning its result or throwing its
759		* exception. This method may be useful when processing
760		* collections of tasks when some have been cancelled or otherwise
761		* known to have aborted.
762		*/
763		public final void quietlyInvoke() {
764	<	doInvoke();
764	>	if (status >= 0) {
765	>	boolean completed;
766	>	try {
767	>	completed = exec();
768	>	} catch (Throwable rex) {
769	>	setExceptionalCompletion(rex);
770	>	return;
771	>	}
772	>	if (completed)
773	>	setCompletion(NORMAL);
774	>	else
775	>	quietlyJoin();
776	>	}
777		}
778
779		/**
#	Line 1073 | Line 1095 | public abstract class ForkJoinTask<V> im
1095		private static final long serialVersionUID = -7721805057305804111L;
1096
1097		/**
1098	<	* Saves the state to a stream.
1098	>	* Saves the state to a stream (that is, serializes it).
1099		*
1100		* @serialData the current run status and the exception thrown
1101		* during execution, or {@code null} if none
#	Line 1086 | Line 1108 | public abstract class ForkJoinTask<V> im
1108		}
1109
1110		/**
1111	<	* Reconstitutes the instance from a stream.
1111	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1112		*
1113		* @param s the stream
1114		*/

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