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root/jsr166/jsr166/src/jsr166e/ForkJoinTask.java

Comparing jsr166/src/jsr166e/ForkJoinTask.java (file contents):
Revision 1.8 by jsr166, Sun Dec 30 02:05:53 2012 UTC vs.
Revision 1.18 by jsr166, Tue Oct 13 19:45:34 2015 UTC

#	Line 134 | Line 134 | import java.lang.reflect.Constructor;
134		* (DAG). Otherwise, executions may encounter a form of deadlock as
135		* tasks cyclically wait for each other.  However, this framework
136		* supports other methods and techniques (for example the use of
137	<	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
137	>	* {@link java.util.concurrent.Phaser Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
138		* may be of use in constructing custom subclasses for problems that
139	<	* are not statically structured as DAGs. To support such usages a
139	>	* are not statically structured as DAGs. To support such usages, a
140		* ForkJoinTask may be atomically <em>tagged</em> with a {@code short}
141		* value using {@link #setForkJoinTaskTag} or {@link
142		* #compareAndSetForkJoinTaskTag} and checked using {@link
#	Line 285 | Line 285 | public abstract class ForkJoinTask<V> im
285		*/
286		private int externalAwaitDone() {
287		int s;
288	<	ForkJoinPool.externalHelpJoin(this);
289	<	boolean interrupted = false;
290	<	while ((s = status) >= 0) {
291	<	if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
292	<	synchronized (this) {
293	<	if (status >= 0) {
294	<	try {
295	<	wait();
296	<	} catch (InterruptedException ie) {
297	<	interrupted = true;
288	>	ForkJoinPool cp = ForkJoinPool.common;
289	>	if ((s = status) >= 0) {
290	>	if (cp != null) {
291	>	if (this instanceof CountedCompleter)
292	>	s = cp.externalHelpComplete((CountedCompleter<?>)this);
293	>	else if (cp.tryExternalUnpush(this))
294	>	s = doExec();
295	>	}
296	>	if (s >= 0 && (s = status) >= 0) {
297	>	boolean interrupted = false;
298	>	do {
299	>	if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
300	>	synchronized (this) {
301	>	if (status >= 0) {
302	>	try {
303	>	wait();
304	>	} catch (InterruptedException ie) {
305	>	interrupted = true;
306	>	}
307	>	}
308	>	else
309	>	notifyAll();
310		}
311		}
312	<	else
313	<	notifyAll();
314	<	}
312	>	} while ((s = status) >= 0);
313	>	if (interrupted)
314	>	Thread.currentThread().interrupt();
315		}
316		}
305	–	if (interrupted)
306	–	Thread.currentThread().interrupt();
317		return s;
318		}
319
#	Line 312 | Line 322 | public abstract class ForkJoinTask<V> im
322		*/
323		private int externalInterruptibleAwaitDone() throws InterruptedException {
324		int s;
325	+	ForkJoinPool cp = ForkJoinPool.common;
326		if (Thread.interrupted())
327		throw new InterruptedException();
328	<	ForkJoinPool.externalHelpJoin(this);
328	>	if ((s = status) >= 0 && cp != null) {
329	>	if (this instanceof CountedCompleter)
330	>	cp.externalHelpComplete((CountedCompleter<?>)this);
331	>	else if (cp.tryExternalUnpush(this))
332	>	doExec();
333	>	}
334		while ((s = status) >= 0) {
335		if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
336		synchronized (this) {
#	Line 395 | Line 411 | public abstract class ForkJoinTask<V> im
411		final Throwable ex;
412		ExceptionNode next;
413		final long thrower;  // use id not ref to avoid weak cycles
414	+	final int hashCode;  // store task hashCode before weak ref disappears
415		ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
416		super(task, exceptionTableRefQueue);
417		this.ex = ex;
418		this.next = next;
419		this.thrower = Thread.currentThread().getId();
420	+	this.hashCode = System.identityHashCode(task);
421		}
422		}
423
#	Line 468 | Line 486 | public abstract class ForkJoinTask<V> im
486		}
487
488		/**
489	<	* Removes exception node and clears status
489	>	* Removes exception node and clears status.
490		*/
491		private void clearExceptionalCompletion() {
492		int h = System.identityHashCode(this);
#	Line 558 | Line 576 | public abstract class ForkJoinTask<V> im
576		/**
577		* Poll stale refs and remove them. Call only while holding lock.
578		*/
579	+	/**
580	+	* Poll stale refs and remove them. Call only while holding lock.
581	+	*/
582		private static void expungeStaleExceptions() {
583		for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
584		if (x instanceof ExceptionNode) {
585	<	ForkJoinTask<?> key = ((ExceptionNode)x).get();
585	>	int hashCode = ((ExceptionNode)x).hashCode;
586		ExceptionNode[] t = exceptionTable;
587	<	int i = System.identityHashCode(key) & (t.length - 1);
587	>	int i = hashCode & (t.length - 1);
588		ExceptionNode e = t[i];
589		ExceptionNode pred = null;
590		while (e != null) {
#	Line 600 | Line 621 | public abstract class ForkJoinTask<V> im
621		/**
622		* A version of "sneaky throw" to relay exceptions
623		*/
624	<	static void rethrow(final Throwable ex) {
625	<	if (ex != null) {
626	<	if (ex instanceof Error)
606	<	throw (Error)ex;
607	<	if (ex instanceof RuntimeException)
608	<	throw (RuntimeException)ex;
609	<	throw uncheckedThrowable(ex, RuntimeException.class);
610	<	}
624	>	static void rethrow(Throwable ex) {
625	>	if (ex != null)
626	>	ForkJoinTask.<RuntimeException>uncheckedThrow(ex);
627		}
628
629		/**
#	Line 616 | Line 632 | public abstract class ForkJoinTask<V> im
632		* unchecked exceptions
633		*/
634		@SuppressWarnings("unchecked") static <T extends Throwable>
635	<	T uncheckedThrowable(final Throwable t, final Class<T> c) {
636	<	return (T)t; // rely on vacuous cast
635	>	void uncheckedThrow(Throwable t) throws T {
636	>	throw (T)t; // rely on vacuous cast
637		}
638
639		/**
#	Line 652 | Line 668 | public abstract class ForkJoinTask<V> im
668		if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)
669		((ForkJoinWorkerThread)t).workQueue.push(this);
670		else
671	<	ForkJoinPool.commonPool.externalPush(this);
671	>	ForkJoinPool.common.externalPush(this);
672		return this;
673		}
674
#	Line 771 | Line 787 | public abstract class ForkJoinTask<V> im
787		* unprocessed.
788		*
789		* @param tasks the collection of tasks
790	+	* @param <T> the type of the values returned from the tasks
791		* @return the tasks argument, to simplify usage
792		* @throws NullPointerException if tasks or any element are null
793		*/
#	Line 828 | Line 845 | public abstract class ForkJoinTask<V> im
845		* <p>This method is designed to be invoked by <em>other</em>
846		* tasks. To terminate the current task, you can just return or
847		* throw an unchecked exception from its computation method, or
848	<	* invoke {@link #completeExceptionally}.
848	>	* invoke {@link #completeExceptionally(Throwable)}.
849		*
850		* @param mayInterruptIfRunning this value has no effect in the
851		* default implementation because interrupts are not used to
#	Line 980 | Line 997 | public abstract class ForkJoinTask<V> im
997		// Messy in part because we measure in nanosecs, but wait in millisecs
998		int s; long ms;
999		long ns = unit.toNanos(timeout);
1000	+	ForkJoinPool cp;
1001		if ((s = status) >= 0 && ns > 0L) {
1002		long deadline = System.nanoTime() + ns;
1003		ForkJoinPool p = null;
#	Line 991 | Line 1009 | public abstract class ForkJoinTask<V> im
1009		w = wt.workQueue;
1010		p.helpJoinOnce(w, this); // no retries on failure
1011		}
1012	<	else
1013	<	ForkJoinPool.externalHelpJoin(this);
1012	>	else if ((cp = ForkJoinPool.common) != null) {
1013	>	if (this instanceof CountedCompleter)
1014	>	cp.externalHelpComplete((CountedCompleter<?>)this);
1015	>	else if (cp.tryExternalUnpush(this))
1016	>	doExec();
1017	>	}
1018		boolean canBlock = false;
1019		boolean interrupted = false;
1020		try {
#	Line 1000 | Line 1022 | public abstract class ForkJoinTask<V> im
1022		if (w != null && w.qlock < 0)
1023		cancelIgnoringExceptions(this);
1024		else if (!canBlock) {
1025	<	if (p == null || p.tryCompensate())
1025	>	if (p == null || p.tryCompensate(p.ctl))
1026		canBlock = true;
1027		}
1028		else {
#	Line 1064 | Line 1086 | public abstract class ForkJoinTask<V> im
1086
1087		/**
1088		* Possibly executes tasks until the pool hosting the current task
1089	<	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
1090	<	* be of use in designs in which many tasks are forked, but none
1091	<	* are explicitly joined, instead executing them until all are
1092	<	* processed.
1089	>	* {@linkplain ForkJoinPool#isQuiescent is quiescent}.  This
1090	>	* method may be of use in designs in which many tasks are forked,
1091	>	* but none are explicitly joined, instead executing them until
1092	>	* all are processed.
1093		*/
1094		public static void helpQuiesce() {
1095		Thread t;
#	Line 1076 | Line 1098 | public abstract class ForkJoinTask<V> im
1098		wt.pool.helpQuiescePool(wt.workQueue);
1099		}
1100		else
1101	<	ForkJoinPool.externalHelpQuiescePool();
1101	>	ForkJoinPool.quiesceCommonPool();
1102		}
1103
1104		/**
#	Line 1141 | Line 1163 | public abstract class ForkJoinTask<V> im
1163		Thread t;
1164		return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
1165		((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) :
1166	<	ForkJoinPool.tryExternalUnpush(this));
1166	>	ForkJoinPool.common.tryExternalUnpush(this));
1167		}
1168
1169		/**
#	Line 1310 | Line 1332 | public abstract class ForkJoinTask<V> im
1332		*
1333		* @param e the expected tag value
1334		* @param tag the new tag value
1335	<	* @return true if successful; i.e., the current value was
1335	>	* @return {@code true} if successful; i.e., the current value was
1336		* equal to e and is now tag.
1337		* @since 1.8
1338		*/
#	Line 1325 | Line 1347 | public abstract class ForkJoinTask<V> im
1347		}
1348
1349		/**
1350	<	* Adaptor for Runnables. This implements RunnableFuture
1350	>	* Adapter for Runnables. This implements RunnableFuture
1351		* to be compliant with AbstractExecutorService constraints
1352		* when used in ForkJoinPool.
1353		*/
#	Line 1346 | Line 1368 | public abstract class ForkJoinTask<V> im
1368		}
1369
1370		/**
1371	<	* Adaptor for Runnables without results
1371	>	* Adapter for Runnables without results
1372		*/
1373		static final class AdaptedRunnableAction extends ForkJoinTask<Void>
1374		implements RunnableFuture<Void> {
#	Line 1363 | Line 1385 | public abstract class ForkJoinTask<V> im
1385		}
1386
1387		/**
1388	<	* Adaptor for Callables
1388	>	* Adapter for Runnables in which failure forces worker exception
1389	>	*/
1390	>	static final class RunnableExecuteAction extends ForkJoinTask<Void> {
1391	>	final Runnable runnable;
1392	>	RunnableExecuteAction(Runnable runnable) {
1393	>	if (runnable == null) throw new NullPointerException();
1394	>	this.runnable = runnable;
1395	>	}
1396	>	public final Void getRawResult() { return null; }
1397	>	public final void setRawResult(Void v) { }
1398	>	public final boolean exec() { runnable.run(); return true; }
1399	>	void internalPropagateException(Throwable ex) {
1400	>	rethrow(ex); // rethrow outside exec() catches.
1401	>	}
1402	>	private static final long serialVersionUID = 5232453952276885070L;
1403	>	}
1404	>
1405	>	/**
1406	>	* Adapter for Callables
1407		*/
1408		static final class AdaptedCallable<T> extends ForkJoinTask<T>
1409		implements RunnableFuture<T> {
#	Line 1410 | Line 1450 | public abstract class ForkJoinTask<V> im
1450		*
1451		* @param runnable the runnable action
1452		* @param result the result upon completion
1453	+	* @param <T> the type of the result
1454		* @return the task
1455		*/
1456		public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
#	Line 1423 | Line 1464 | public abstract class ForkJoinTask<V> im
1464		* encountered into {@code RuntimeException}.
1465		*
1466		* @param callable the callable action
1467	+	* @param <T> the type of the callable's result
1468		* @return the task
1469		*/
1470		public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
#	Line 1436 | Line 1478 | public abstract class ForkJoinTask<V> im
1478		/**
1479		* Saves this task to a stream (that is, serializes it).
1480		*
1481	+	* @param s the stream
1482	+	* @throws java.io.IOException if an I/O error occurs
1483		* @serialData the current run status and the exception thrown
1484		* during execution, or {@code null} if none
1485		*/
#	Line 1447 | Line 1491 | public abstract class ForkJoinTask<V> im
1491
1492		/**
1493		* Reconstitutes this task from a stream (that is, deserializes it).
1494	+	* @param s the stream
1495	+	* @throws ClassNotFoundException if the class of a serialized object
1496	+	*         could not be found
1497	+	* @throws java.io.IOException if an I/O error occurs
1498		*/
1499		private void readObject(java.io.ObjectInputStream s)
1500		throws java.io.IOException, ClassNotFoundException {
#	Line 1484 | Line 1532 | public abstract class ForkJoinTask<V> im
1532		private static sun.misc.Unsafe getUnsafe() {
1533		try {
1534		return sun.misc.Unsafe.getUnsafe();
1535	<	} catch (SecurityException se) {
1536	<	try {
1537	<	return java.security.AccessController.doPrivileged
1538	<	(new java.security
1539	<	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1540	<	public sun.misc.Unsafe run() throws Exception {
1541	<	java.lang.reflect.Field f = sun.misc
1542	<	.Unsafe.class.getDeclaredField("theUnsafe");
1543	<	f.setAccessible(true);
1544	<	return (sun.misc.Unsafe) f.get(null);
1545	<	}});
1546	<	} catch (java.security.PrivilegedActionException e) {
1547	<	throw new RuntimeException("Could not initialize intrinsics",
1548	<	e.getCause());
1549	<	}
1535	>	} catch (SecurityException tryReflectionInstead) {}
1536	>	try {
1537	>	return java.security.AccessController.doPrivileged
1538	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1539	>	public sun.misc.Unsafe run() throws Exception {
1540	>	Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
1541	>	for (java.lang.reflect.Field f : k.getDeclaredFields()) {
1542	>	f.setAccessible(true);
1543	>	Object x = f.get(null);
1544	>	if (k.isInstance(x))
1545	>	return k.cast(x);
1546	>	}
1547	>	throw new NoSuchFieldError("the Unsafe");
1548	>	}});
1549	>	} catch (java.security.PrivilegedActionException e) {
1550	>	throw new RuntimeException("Could not initialize intrinsics",
1551	>	e.getCause());
1552		}
1553		}
1504	–
1554		}

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