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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 1.55 by dl, Sun Aug 29 23:34:46 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
209		* @return status on exit
210		*/
211	<	private int setExceptionalCompletion(Throwable rex) {
211	>	private void setExceptionalCompletion(Throwable rex) {
212		exceptionMap.put(this, rex);
213	<	return setCompletion(EXCEPTIONAL);
213	>	setCompletion(EXCEPTIONAL);
214		}
215
216		/**
217	<	* Blocks a worker thread until completion. Called only by pool.
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 void internalAwaitDone() {
222		int s;         // the odd construction reduces lock bias effects
#	Line 232 | Line 233 | public abstract class ForkJoinTask<V> im
233		}
234
235		/**
236	<	* Blocks a non-worker-thread until completion.
236	>	* Blocks a worker thread until completed or timed out.  Called
237	>	* only by pool.
238	>	*
239		* @return status on exit
240		*/
241	<	private int externalAwaitDone() {
241	>	final int internalAwaitDone(long millis) {
242	>	int s;
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-worker-thread until completion.
259	>	*/
260	>	private void externalAwaitDone() {
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 ((s = status) >= 0) {
266	>	while (status >= 0) {
267		try {
268		wait();
269		} catch (InterruptedException ie) {
#	Line 254 | Line 276 | public abstract class ForkJoinTask<V> im
276		}
277		}
278		}
257	–	return s;
279		}
280
281		/**
#	Line 262 | Line 283 | public abstract class ForkJoinTask<V> im
283		* doesn't wait for completion otherwise. Primary execution method
284		* for ForkJoinWorkerThread.
285		*/
286	<	final void tryExec() {
286	>	final void quietlyExec() {
287		try {
288		if (status < 0 || !exec())
289		return;
#	Line 273 | Line 294 | public abstract class ForkJoinTask<V> im
294		setCompletion(NORMAL); // must be outside try block
295		}
296
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	–
297		// public methods
298
299		/**
#	Line 365 | Line 329 | public abstract class ForkJoinTask<V> im
329		* @return the computed result
330		*/
331		public final V join() {
332	<	return reportResult(doJoin());
332	>	quietlyJoin();
333	>	Throwable ex;
334	>	if (status < NORMAL && (ex = getException()) != null)
335	>	UNSAFE.throwException(ex);
336	>	return getRawResult();
337		}
338
339		/**
#	Line 376 | Line 344 | public abstract class ForkJoinTask<V> im
344		* @return the computed result
345		*/
346		public final V invoke() {
347	<	return reportResult(doInvoke());
347	>	quietlyInvoke();
348	>	Throwable ex;
349	>	if (status < NORMAL && (ex = getException()) != null)
350	>	UNSAFE.throwException(ex);
351	>	return getRawResult();
352		}
353
354		/**
#	Line 434 | Line 406 | public abstract class ForkJoinTask<V> im
406		}
407		else if (i != 0)
408		t.fork();
409	<	else if (t.doInvoke() < NORMAL && ex == null)
410	<	ex = t.getException();
409	>	else {
410	>	t.quietlyInvoke();
411	>	if (ex == null && t.status < NORMAL)
412	>	ex = t.getException();
413	>	}
414		}
415		for (int i = 1; i <= last; ++i) {
416		ForkJoinTask<?> t = tasks[i];
417		if (t != null) {
418		if (ex != null)
419		t.cancel(false);
420	<	else if (t.doJoin() < NORMAL && ex == null)
421	<	ex = t.getException();
420	>	else {
421	>	t.quietlyJoin();
422	>	if (ex == null && t.status < NORMAL)
423	>	ex = t.getException();
424	>	}
425		}
426		}
427		if (ex != null)
#	Line 490 | Line 468 | public abstract class ForkJoinTask<V> im
468		}
469		else if (i != 0)
470		t.fork();
471	<	else if (t.doInvoke() < NORMAL && ex == null)
472	<	ex = t.getException();
471	>	else {
472	>	t.quietlyInvoke();
473	>	if (ex == null && t.status < NORMAL)
474	>	ex = t.getException();
475	>	}
476		}
477		for (int i = 1; i <= last; ++i) {
478		ForkJoinTask<?> t = ts.get(i);
479		if (t != null) {
480		if (ex != null)
481		t.cancel(false);
482	<	else if (t.doJoin() < NORMAL && ex == null)
483	<	ex = t.getException();
482	>	else {
483	>	t.quietlyJoin();
484	>	if (ex == null && t.status < NORMAL)
485	>	ex = t.getException();
486	>	}
487		}
488		}
489		if (ex != null)
#	Line 532 | Line 516 | public abstract class ForkJoinTask<V> im
516		* @return {@code true} if this task is now cancelled
517		*/
518		public boolean cancel(boolean mayInterruptIfRunning) {
519	<	return setCompletion(CANCELLED) == CANCELLED;
519	>	setCompletion(CANCELLED);
520	>	return status == CANCELLED;
521		}
522
523		/**
524	<	* Cancels, ignoring any exceptions it throws. Used during worker
525	<	* and pool shutdown.
524	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
525	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
526	>	* exceptions, but if it does anyway, we have no recourse during
527	>	* shutdown, so guard against this case.
528		*/
529		final void cancelIgnoringExceptions() {
530		try {
#	Line 645 | Line 632 | public abstract class ForkJoinTask<V> im
632		}
633
634		public final V get() throws InterruptedException, ExecutionException {
635	<	int s = doJoin();
635	>	quietlyJoin();
636		if (Thread.interrupted())
637		throw new InterruptedException();
638	+	int s = status;
639		if (s < NORMAL) {
640		Throwable ex;
641		if (s == CANCELLED)
#	Line 665 | Line 653 | public abstract class ForkJoinTask<V> im
653		if (t instanceof ForkJoinWorkerThread) {
654		ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
655		if (status >= 0 && w.unpushTask(this))
656	<	tryExec();
656	>	quietlyExec();
657		pool = w.pool;
658		}
659		else
660		pool = null;
661		/*
662	<	* Timed wait loop intermixes cases for fj (pool != null) and
662	>	* Timed wait loop intermixes cases for FJ (pool != null) and
663		* non FJ threads. For FJ, decrement pool count but don't try
664		* for replacement; increment count on completion. For non-FJ,
665		* deal with interrupts. This is messy, but a little less so
#	Line 679 | Line 667 | public abstract class ForkJoinTask<V> im
667		*/
668		boolean interrupted = false;
669		boolean dec = false; // true if pool count decremented
670	+	long nanos = unit.toNanos(timeout);
671		for (;;) {
672		if (Thread.interrupted() && pool == null) {
673		interrupted = true;
#	Line 687 | Line 676 | public abstract class ForkJoinTask<V> im
676		int s = status;
677		if (s < 0)
678		break;
679	<	if (UNSAFE.compareAndSwapInt(this, statusOffset,
691	<	s, s | SIGNAL)) {
679	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
680		long startTime = System.nanoTime();
693	–	long nanos = unit.toNanos(timeout);
681		long nt; // wait time
682		while (status >= 0 &&
683		(nt = nanos - (System.nanoTime() - startTime)) > 0) {
#	Line 734 | Line 721 | public abstract class ForkJoinTask<V> im
721		}
722
723		/**
724	<	* Joins this task, without returning its result or throwing an
724	>	* Joins this task, without returning its result or throwing its
725		* exception. This method may be useful when processing
726		* collections of tasks when some have been cancelled or otherwise
727		* known to have aborted.
728		*/
729		public final void quietlyJoin() {
730	<	doJoin();
730	>	Thread t;
731	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
732	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
733	>	if (status >= 0) {
734	>	if (w.unpushTask(this)) {
735	>	boolean completed;
736	>	try {
737	>	completed = exec();
738	>	} catch (Throwable rex) {
739	>	setExceptionalCompletion(rex);
740	>	return;
741	>	}
742	>	if (completed) {
743	>	setCompletion(NORMAL);
744	>	return;
745	>	}
746	>	}
747	>	w.joinTask(this);
748	>	}
749	>	}
750	>	else
751	>	externalAwaitDone();
752		}
753
754		/**
755		* Commences performing this task and awaits its completion if
756	<	* necessary, without returning its result or throwing an
756	>	* necessary, without returning its result or throwing its
757		* exception. This method may be useful when processing
758		* collections of tasks when some have been cancelled or otherwise
759		* known to have aborted.
760		*/
761		public final void quietlyInvoke() {
762	<	doInvoke();
762	>	if (status >= 0) {
763	>	boolean completed;
764	>	try {
765	>	completed = exec();
766	>	} catch (Throwable rex) {
767	>	setExceptionalCompletion(rex);
768	>	return;
769	>	}
770	>	if (completed)
771	>	setCompletion(NORMAL);
772	>	else
773	>	quietlyJoin();
774	>	}
775		}
776
777		/**

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