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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.69 by dl, Mon Nov 22 12:24:34 2010 UTC vs.
Revision 1.70 by dl, Tue Nov 23 00:10:39 2010 UTC

#	Line 134 | Line 134 | import java.util.concurrent.TimeoutExcep
134		* computation. Large tasks should be split into smaller subtasks,
135		* usually via recursive decomposition. As a very rough rule of thumb,
136		* a task should perform more than 100 and less than 10000 basic
137	<	* computational steps. If tasks are too big, then parallelism cannot
138	<	* improve throughput. If too small, then memory and internal task
139	<	* maintenance overhead may overwhelm processing.
137	>	* computational steps, and should avoid indefinite looping. If tasks
138	>	* are too big, then parallelism cannot improve throughput. If too
139	>	* small, then memory and internal task maintenance overhead may
140	>	* overwhelm processing.
141		*
142		* <p>This class provides {@code adapt} methods for {@link Runnable}
143		* and {@link Callable}, that may be of use when mixing execution of
#	Line 233 | Line 234 | public abstract class ForkJoinTask<V> im
234		}
235
236		/**
237	<	* Blocks a worker thread until completion. Called only by
238	<	* pool. Currently unused -- pool-based waits use timeout
238	<	* version below.
237	>	* Blocks a worker thread until completed or timed out.  Called
238	>	* only by pool.
239		*/
240	<	final void internalAwaitDone() {
241	<	int s;         // the odd construction reduces lock bias effects
242	<	while ((s = status) >= 0) {
243	<	try {
240	>	final void internalAwaitDone(long millis, int nanos) {
241	>	if (status >= 0) {
242	>	try {     // the odd construction reduces lock bias effects
243		synchronized (this) {
244	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
245	<	wait();
244	>	if (status > 0 ||
245	>	UNSAFE.compareAndSwapInt(this, statusOffset,
246	>	0, SIGNAL))
247	>	wait(millis, nanos);
248		}
249		} catch (InterruptedException ie) {
250		cancelIfTerminating();
#	Line 252 | Line 253 | public abstract class ForkJoinTask<V> im
253		}
254
255		/**
256	<	* Blocks a worker thread until completed or timed out.  Called
256	<	* only by pool.
257	<	*
258	<	* @return status on exit
256	>	* Blocks a non-worker-thread until completion.
257		*/
258	<	final int internalAwaitDone(long millis, int nanos) {
259	<	int s;
260	<	if ((s = status) >= 0) {
261	<	try {
262	<	synchronized (this) {
263	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
264	<	wait(millis, nanos);
258	>	private void externalAwaitDone() {
259	>	if (status >= 0) {
260	>	boolean interrupted = false;
261	>	synchronized(this) {
262	>	int s;
263	>	while ((s = status) >= 0) {
264	>	if (s == 0 &&
265	>	!UNSAFE.compareAndSwapInt(this, statusOffset,
266	>	0, SIGNAL))
267	>	continue;
268	>	try {
269	>	wait();
270	>	} catch (InterruptedException ie) {
271	>	interrupted = true;
272	>	}
273		}
268	–	} catch (InterruptedException ie) {
269	–	cancelIfTerminating();
274		}
275	<	s = status;
275	>	if (interrupted)
276	>	Thread.currentThread().interrupt();
277		}
273	–	return s;
278		}
279
280		/**
281	<	* Blocks a non-worker-thread until completion.
281	>	* Blocks a non-worker-thread until completion or interruption or timeout
282		*/
283	<	private void externalAwaitDone() {
284	<	int s;
285	<	while ((s = status) >= 0) {
286	<	synchronized (this) {
287	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
288	<	boolean interrupted = false;
289	<	while (status >= 0) {
290	<	try {
291	<	wait();
292	<	} catch (InterruptedException ie) {
293	<	interrupted = true;
294	<	}
295	<	}
296	<	if (interrupted)
297	<	Thread.currentThread().interrupt();
298	<	break;
283	>	private void externalInterruptibleAwaitDone(boolean timed, long nanos)
284	>	throws InterruptedException {
285	>	if (Thread.interrupted())
286	>	throw new InterruptedException();
287	>	if (status >= 0) {
288	>	long startTime = timed ? System.nanoTime() : 0L;
289	>	synchronized(this) {
290	>	int s;
291	>	while ((s = status) >= 0) {
292	>	long nt;
293	>	if (s == 0 &&
294	>	!UNSAFE.compareAndSwapInt(this, statusOffset,
295	>	0, SIGNAL))
296	>	continue;
297	>	else if (!timed)
298	>	wait();
299	>	else if ((nt = nanos - (System.nanoTime()-startTime)) > 0L)
300	>	wait(nt / 1000000, (int)(nt % 1000000));
301	>	else
302	>	break;
303		}
304		}
305		}
#	Line 326 | Line 334 | public abstract class ForkJoinTask<V> im
334		* #isDone} returning {@code true}.
335		*
336		* <p>This method may be invoked only from within {@code
337	<	* ForkJoinTask} computations (as may be determined using method
337	>	* ForkJoinPool} computations (as may be determined using method
338		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
339		* result in exceptions or errors, possibly including {@code
340		* ClassCastException}.
#	Line 678 | Line 686 | public abstract class ForkJoinTask<V> im
686		* member of a ForkJoinPool and was interrupted while waiting
687		*/
688		public final V get() throws InterruptedException, ExecutionException {
689	<	int s;
690	<	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
689	>	Thread t = Thread.currentThread();
690	>	if (t instanceof ForkJoinWorkerThread)
691		quietlyJoin();
692	<	s = status;
693	<	}
694	<	else {
695	<	while ((s = status) >= 0) {
688	<	synchronized (this) { // interruptible form of awaitDone
689	<	if (UNSAFE.compareAndSwapInt(this, statusOffset,
690	<	s, SIGNAL)) {
691	<	while (status >= 0)
692	<	wait();
693	<	}
694	<	}
695	<	}
696	<	}
697	<	if (s < NORMAL) {
692	>	else
693	>	externalInterruptibleAwaitDone(false, 0L);
694	>	int s = status;
695	>	if (s != NORMAL) {
696		Throwable ex;
697		if (s == CANCELLED)
698		throw new CancellationException();
#	Line 721 | Line 719 | public abstract class ForkJoinTask<V> im
719		public final V get(long timeout, TimeUnit unit)
720		throws InterruptedException, ExecutionException, TimeoutException {
721		long nanos = unit.toNanos(timeout);
722	<	if (status >= 0) {
723	<	Thread t = Thread.currentThread();
724	<	if (t instanceof ForkJoinWorkerThread) {
725	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
726	<	boolean completed = false; // timed variant of quietlyJoin
727	<	if (w.unpushTask(this)) {
728	<	try {
731	<	completed = exec();
732	<	} catch (Throwable rex) {
733	<	setExceptionalCompletion(rex);
734	<	}
735	<	}
736	<	if (completed)
737	<	setCompletion(NORMAL);
738	<	else if (status >= 0)
739	<	w.joinTask(this, true, nanos);
740	<	}
741	<	else if (Thread.interrupted())
742	<	throw new InterruptedException();
743	<	else {
744	<	long startTime = System.nanoTime();
745	<	int s; long nt;
746	<	while ((s = status) >= 0 &&
747	<	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
748	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,
749	<	SIGNAL)) {
750	<	long ms = nt / 1000000;
751	<	int ns = (int) (nt % 1000000);
752	<	synchronized (this) {
753	<	if (status >= 0)
754	<	wait(ms, ns); // exit on IE throw
755	<	}
756	<	}
757	<	}
758	<	}
759	<	}
760	<	int es = status;
761	<	if (es != NORMAL) {
722	>	Thread t = Thread.currentThread();
723	>	if (t instanceof ForkJoinWorkerThread)
724	>	((ForkJoinWorkerThread)t).joinTask(this, true, nanos);
725	>	else
726	>	externalInterruptibleAwaitDone(true, nanos);
727	>	int s = status;
728	>	if (s != NORMAL) {
729		Throwable ex;
730	<	if (es == CANCELLED)
730	>	if (s == CANCELLED)
731		throw new CancellationException();
732	<	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
732	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
733		throw new ExecutionException(ex);
734		throw new TimeoutException();
735		}

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