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root/jsr166/jsr166/src/jsr166y/ForkJoinPool.java

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.19 by jsr166, Fri Jul 24 18:57:56 2009 UTC vs.
Revision 1.52 by dl, Sat Dec 5 11:39:03 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import java.util.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.locks.*;
11	<	import java.util.concurrent.atomic.*;
12	<	import sun.misc.Unsafe;
13	<	import java.lang.reflect.*;
10	>
11	>	import java.util.ArrayList;
12	>	import java.util.Arrays;
13	>	import java.util.Collection;
14	>	import java.util.Collections;
15	>	import java.util.List;
16	>	import java.util.concurrent.locks.Condition;
17	>	import java.util.concurrent.locks.LockSupport;
18	>	import java.util.concurrent.locks.ReentrantLock;
19	>	import java.util.concurrent.atomic.AtomicInteger;
20	>	import java.util.concurrent.atomic.AtomicLong;
21
22		/**
23	<	* An {@link ExecutorService} for running {@link ForkJoinTask}s.  A
24	<	* ForkJoinPool provides the entry point for submissions from
25	<	* non-ForkJoinTasks, as well as management and monitoring operations.
26	<	* Normally a single ForkJoinPool is used for a large number of
20	<	* submitted tasks. Otherwise, use would not usually outweigh the
21	<	* construction and bookkeeping overhead of creating a large set of
22	<	* threads.
23	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.
24	>	* A {@code ForkJoinPool} provides the entry point for submissions
25	>	* from non-{@code ForkJoinTask}s, as well as management and
26	>	* monitoring operations.
27		*
28	<	* <p>ForkJoinPools differ from other kinds of Executors mainly in
29	<	* that they provide <em>work-stealing</em>: all threads in the pool
30	<	* attempt to find and execute subtasks created by other active tasks
31	<	* (eventually blocking if none exist). This makes them efficient when
32	<	* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
33	<	* as the mixed execution of some plain Runnable- or Callable- based
34	<	* activities along with ForkJoinTasks. When setting
35	<	* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for
36	<	* use with fine-grained tasks that are never joined. Otherwise, other
37	<	* ExecutorService implementations are typically more appropriate
38	<	* choices.
28	>	* <p>A {@code ForkJoinPool} differs from other kinds of {@link
29	>	* ExecutorService} mainly by virtue of employing
30	>	* <em>work-stealing</em>: all threads in the pool attempt to find and
31	>	* execute subtasks created by other active tasks (eventually blocking
32	>	* waiting for work if none exist). This enables efficient processing
33	>	* when most tasks spawn other subtasks (as do most {@code
34	>	* ForkJoinTask}s). A {@code ForkJoinPool} may also be used for mixed
35	>	* execution of some plain {@code Runnable}- or {@code Callable}-
36	>	* based activities along with {@code ForkJoinTask}s. When setting
37	>	* {@linkplain #setAsyncMode async mode}, a {@code ForkJoinPool} may
38	>	* also be appropriate for use with fine-grained tasks of any form
39	>	* that are never joined. Otherwise, other {@code ExecutorService}
40	>	* implementations are typically more appropriate choices.
41		*
42	<	* <p>A ForkJoinPool may be constructed with a given parallelism level
43	<	* (target pool size), which it attempts to maintain by dynamically
44	<	* adding, suspending, or resuming threads, even if some tasks are
45	<	* waiting to join others. However, no such adjustments are performed
46	<	* in the face of blocked IO or other unmanaged synchronization. The
47	<	* nested {@code ManagedBlocker} interface enables extension of
48	<	* the kinds of synchronization accommodated.  The target parallelism
49	<	* level may also be changed dynamically ({@code setParallelism})
50	<	* and thread construction can be limited using methods
51	<	* {@code setMaximumPoolSize} and/or
52	<	* {@code setMaintainsParallelism}.
42	>	* <p>A {@code ForkJoinPool} is constructed with a given target
43	>	* parallelism level; by default, equal to the number of available
44	>	* processors. Unless configured otherwise via {@link
45	>	* #setMaintainsParallelism}, the pool attempts to maintain this
46	>	* number of active (or available) threads by dynamically adding,
47	>	* suspending, or resuming internal worker threads, even if some tasks
48	>	* are stalled waiting to join others. However, no such adjustments
49	>	* are performed in the face of blocked IO or other unmanaged
50	>	* synchronization. The nested {@link ManagedBlocker} interface
51	>	* enables extension of the kinds of synchronization accommodated.
52	>	* The target parallelism level may also be changed dynamically
53	>	* ({@link #setParallelism}). The total number of threads may be
54	>	* limited using method {@link #setMaximumPoolSize}, in which case it
55	>	* may become possible for the activities of a pool to stall due to
56	>	* the lack of available threads to process new tasks.
57		*
58		* <p>In addition to execution and lifecycle control methods, this
59		* class provides status check methods (for example
60	<	* {@code getStealCount}) that are intended to aid in developing,
60	>	* {@link #getStealCount}) that are intended to aid in developing,
61		* tuning, and monitoring fork/join applications. Also, method
62	<	* {@code toString} returns indications of pool state in a
62	>	* {@link #toString} returns indications of pool state in a
63		* convenient form for informal monitoring.
64		*
65	+	* <p><b>Sample Usage.</b> Normally a single {@code ForkJoinPool} is
66	+	* used for all parallel task execution in a program or subsystem.
67	+	* Otherwise, use would not usually outweigh the construction and
68	+	* bookkeeping overhead of creating a large set of threads. For
69	+	* example, a common pool could be used for the {@code SortTasks}
70	+	* illustrated in {@link RecursiveAction}. Because {@code
71	+	* ForkJoinPool} uses threads in {@linkplain java.lang.Thread#isDaemon
72	+	* daemon} mode, there is typically no need to explicitly {@link
73	+	* #shutdown} such a pool upon program exit.
74	+	*
75	+	* <pre>
76	+	* static final ForkJoinPool mainPool = new ForkJoinPool();
77	+	* ...
78	+	* public void sort(long[] array) {
79	+	*   mainPool.invoke(new SortTask(array, 0, array.length));
80	+	* }
81	+	* </pre>
82	+	*
83		* <p><b>Implementation notes</b>: This implementation restricts the
84		* maximum number of running threads to 32767. Attempts to create
85	<	* pools with greater than the maximum result in
86	<	* IllegalArgumentExceptions.
85	>	* pools with greater than the maximum number result in
86	>	* {@code IllegalArgumentException}.
87	>	*
88	>	* <p>This implementation rejects submitted tasks (that is, by throwing
89	>	* {@link RejectedExecutionException}) only when the pool is shut down.
90		*
91		* @since 1.7
92		* @author Doug Lea
#	Line 74 | Line 105 | public class ForkJoinPool extends Abstra
105		private static final int MAX_THREADS =  0x7FFF;
106
107		/**
108	<	* Factory for creating new ForkJoinWorkerThreads.  A
109	<	* ForkJoinWorkerThreadFactory must be defined and used for
110	<	* ForkJoinWorkerThread subclasses that extend base functionality
111	<	* or initialize threads with different contexts.
108	>	* Factory for creating new {@link ForkJoinWorkerThread}s.
109	>	* A {@code ForkJoinWorkerThreadFactory} must be defined and used
110	>	* for {@code ForkJoinWorkerThread} subclasses that extend base
111	>	* functionality or initialize threads with different contexts.
112		*/
113		public static interface ForkJoinWorkerThreadFactory {
114		/**
115		* Returns a new worker thread operating in the given pool.
116		*
117		* @param pool the pool this thread works in
118	<	* @throws NullPointerException if pool is null
118	>	* @throws NullPointerException if the pool is null
119		*/
120		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
121		}
#	Line 304 | Line 335 | public class ForkJoinPool extends Abstra
335		}
336
337		/**
338	<	* Returns true if argument represents zero active count and
339	<	* nonzero runstate, which is the triggering condition for
338	>	* Returns {@code true} if argument represents zero active count
339	>	* and nonzero runstate, which is the triggering condition for
340		* terminating on shutdown.
341		*/
342		private static boolean canTerminateOnShutdown(int c) {
#	Line 335 | Line 366 | public class ForkJoinPool extends Abstra
366		// Constructors
367
368		/**
369	<	* Creates a ForkJoinPool with a pool size equal to the number of
370	<	* processors available on the system, using the default
371	<	* ForkJoinWorkerThreadFactory.
369	>	* Creates a {@code ForkJoinPool} with parallelism equal to {@link
370	>	* java.lang.Runtime#availableProcessors}, and using the {@linkplain
371	>	* #defaultForkJoinWorkerThreadFactory default thread factory}.
372		*
373		* @throws SecurityException if a security manager exists and
374		*         the caller is not permitted to modify threads
#	Line 350 | Line 381 | public class ForkJoinPool extends Abstra
381		}
382
383		/**
384	<	* Creates a ForkJoinPool with the indicated parallelism level
385	<	* threads and using the default ForkJoinWorkerThreadFactory.
384	>	* Creates a {@code ForkJoinPool} with the indicated parallelism
385	>	* level and using the {@linkplain
386	>	* #defaultForkJoinWorkerThreadFactory default thread factory}.
387		*
388	<	* @param parallelism the number of worker threads
388	>	* @param parallelism the parallelism level
389		* @throws IllegalArgumentException if parallelism less than or
390	<	* equal to zero
390	>	*         equal to zero, or greater than implementation limit
391		* @throws SecurityException if a security manager exists and
392		*         the caller is not permitted to modify threads
393		*         because it does not hold {@link
#	Line 366 | Line 398 | public class ForkJoinPool extends Abstra
398		}
399
400		/**
401	<	* Creates a ForkJoinPool with parallelism equal to the number of
402	<	* processors available on the system and using the given
403	<	* ForkJoinWorkerThreadFactory.
401	>	* Creates a {@code ForkJoinPool} with parallelism equal to {@link
402	>	* java.lang.Runtime#availableProcessors}, and using the given
403	>	* thread factory.
404		*
405		* @param factory the factory for creating new threads
406	<	* @throws NullPointerException if factory is null
406	>	* @throws NullPointerException if the factory is null
407		* @throws SecurityException if a security manager exists and
408		*         the caller is not permitted to modify threads
409		*         because it does not hold {@link
#	Line 382 | Line 414 | public class ForkJoinPool extends Abstra
414		}
415
416		/**
417	<	* Creates a ForkJoinPool with the given parallelism and factory.
417	>	* Creates a {@code ForkJoinPool} with the given parallelism and
418	>	* thread factory.
419		*
420	<	* @param parallelism the targeted number of worker threads
420	>	* @param parallelism the parallelism level
421		* @param factory the factory for creating new threads
422		* @throws IllegalArgumentException if parallelism less than or
423	<	* equal to zero, or greater than implementation limit
424	<	* @throws NullPointerException if factory is null
423	>	*         equal to zero, or greater than implementation limit
424	>	* @throws NullPointerException if the factory is null
425		* @throws SecurityException if a security manager exists and
426		*         the caller is not permitted to modify threads
427		*         because it does not hold {@link
#	Line 416 | Line 449 | public class ForkJoinPool extends Abstra
449		* Creates a new worker thread using factory.
450		*
451		* @param index the index to assign worker
452	<	* @return new worker, or null of factory failed
452	>	* @return new worker, or null if factory failed
453		*/
454		private ForkJoinWorkerThread createWorker(int index) {
455		Thread.UncaughtExceptionHandler h = ueh;
#	Line 437 | Line 470 | public class ForkJoinPool extends Abstra
470		* Currently requires size to be a power of two.
471		*/
472		private static int arraySizeFor(int poolSize) {
473	<	return (poolSize <= 1) ? 1 :
474	<	(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1)));
473	>	if (poolSize <= 1)
474	>	return 1;
475	>	// See Hackers Delight, sec 3.2
476	>	int c = poolSize >= MAX_THREADS ? MAX_THREADS : (poolSize - 1);
477	>	c |= c >>>  1;
478	>	c |= c >>>  2;
479	>	c |= c >>>  4;
480	>	c |= c >>>  8;
481	>	c |= c >>> 16;
482	>	return c + 1;
483		}
484
485		/**
#	Line 485 | Line 526 | public class ForkJoinPool extends Abstra
526		ws = workers;
527		if (ws == null) {
528		int ps = parallelism;
529	+	updateWorkerCount(ps);
530		ws = ensureWorkerArrayCapacity(ps);
531		for (int i = 0; i < ps; ++i) {
532		ForkJoinWorkerThread w = createWorker(i);
533		if (w != null) {
534		ws[i] = w;
535		w.start();
494	–	updateWorkerCount(1);
536		}
537	+	else
538	+	updateWorkerCount(-1);
539		}
540		}
541		} finally {
#	Line 541 | Line 584 | public class ForkJoinPool extends Abstra
584		* Common code for execute, invoke and submit
585		*/
586		private <T> void doSubmit(ForkJoinTask<T> task) {
587	+	if (task == null)
588	+	throw new NullPointerException();
589		if (isShutdown())
590		throw new RejectedExecutionException();
591		if (workers == null)
#	Line 554 | Line 599 | public class ForkJoinPool extends Abstra
599		*
600		* @param task the task
601		* @return the task's result
602	<	* @throws NullPointerException if task is null
603	<	* @throws RejectedExecutionException if pool is shut down
602	>	* @throws NullPointerException if the task is null
603	>	* @throws RejectedExecutionException if the task cannot be
604	>	*         scheduled for execution
605		*/
606		public <T> T invoke(ForkJoinTask<T> task) {
607		doSubmit(task);
#	Line 566 | Line 612 | public class ForkJoinPool extends Abstra
612		* Arranges for (asynchronous) execution of the given task.
613		*
614		* @param task the task
615	<	* @throws NullPointerException if task is null
616	<	* @throws RejectedExecutionException if pool is shut down
615	>	* @throws NullPointerException if the task is null
616	>	* @throws RejectedExecutionException if the task cannot be
617	>	*         scheduled for execution
618		*/
619	<	public <T> void execute(ForkJoinTask<T> task) {
619	>	public void execute(ForkJoinTask<?> task) {
620		doSubmit(task);
621		}
622
623		// AbstractExecutorService methods
624
625	+	/**
626	+	* @throws NullPointerException if the task is null
627	+	* @throws RejectedExecutionException if the task cannot be
628	+	*         scheduled for execution
629	+	*/
630		public void execute(Runnable task) {
631	<	doSubmit(new AdaptedRunnable<Void>(task, null));
631	>	ForkJoinTask<?> job;
632	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
633	>	job = (ForkJoinTask<?>) task;
634	>	else
635	>	job = ForkJoinTask.adapt(task, null);
636	>	doSubmit(job);
637		}
638
639	+	/**
640	+	* @throws NullPointerException if the task is null
641	+	* @throws RejectedExecutionException if the task cannot be
642	+	*         scheduled for execution
643	+	*/
644		public <T> ForkJoinTask<T> submit(Callable<T> task) {
645	<	ForkJoinTask<T> job = new AdaptedCallable<T>(task);
645	>	ForkJoinTask<T> job = ForkJoinTask.adapt(task);
646		doSubmit(job);
647		return job;
648		}
649
650	+	/**
651	+	* @throws NullPointerException if the task is null
652	+	* @throws RejectedExecutionException if the task cannot be
653	+	*         scheduled for execution
654	+	*/
655		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
656	<	ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result);
656	>	ForkJoinTask<T> job = ForkJoinTask.adapt(task, result);
657		doSubmit(job);
658		return job;
659		}
660
661	+	/**
662	+	* @throws NullPointerException if the task is null
663	+	* @throws RejectedExecutionException if the task cannot be
664	+	*         scheduled for execution
665	+	*/
666		public ForkJoinTask<?> submit(Runnable task) {
667	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
667	>	ForkJoinTask<?> job;
668	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
669	>	job = (ForkJoinTask<?>) task;
670	>	else
671	>	job = ForkJoinTask.adapt(task, null);
672		doSubmit(job);
673		return job;
674		}
675
676		/**
677	<	* Adaptor for Runnables. This implements RunnableFuture
678	<	* to be compliant with AbstractExecutorService constraints.
677	>	* Submits a ForkJoinTask for execution.
678	>	*
679	>	* @param task the task to submit
680	>	* @return the task
681	>	* @throws NullPointerException if the task is null
682	>	* @throws RejectedExecutionException if the task cannot be
683	>	*         scheduled for execution
684		*/
685	<	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
686	<	implements RunnableFuture<T> {
687	<	final Runnable runnable;
607	<	final T resultOnCompletion;
608	<	T result;
609	<	AdaptedRunnable(Runnable runnable, T result) {
610	<	if (runnable == null) throw new NullPointerException();
611	<	this.runnable = runnable;
612	<	this.resultOnCompletion = result;
613	<	}
614	<	public T getRawResult() { return result; }
615	<	public void setRawResult(T v) { result = v; }
616	<	public boolean exec() {
617	<	runnable.run();
618	<	result = resultOnCompletion;
619	<	return true;
620	<	}
621	<	public void run() { invoke(); }
622	<	private static final long serialVersionUID = 5232453952276885070L;
685	>	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
686	>	doSubmit(task);
687	>	return task;
688		}
689
625	–	/**
626	–	* Adaptor for Callables
627	–	*/
628	–	static final class AdaptedCallable<T> extends ForkJoinTask<T>
629	–	implements RunnableFuture<T> {
630	–	final Callable<T> callable;
631	–	T result;
632	–	AdaptedCallable(Callable<T> callable) {
633	–	if (callable == null) throw new NullPointerException();
634	–	this.callable = callable;
635	–	}
636	–	public T getRawResult() { return result; }
637	–	public void setRawResult(T v) { result = v; }
638	–	public boolean exec() {
639	–	try {
640	–	result = callable.call();
641	–	return true;
642	–	} catch (Error err) {
643	–	throw err;
644	–	} catch (RuntimeException rex) {
645	–	throw rex;
646	–	} catch (Exception ex) {
647	–	throw new RuntimeException(ex);
648	–	}
649	–	}
650	–	public void run() { invoke(); }
651	–	private static final long serialVersionUID = 2838392045355241008L;
652	–	}
690
691	+	/**
692	+	* @throws NullPointerException       {@inheritDoc}
693	+	* @throws RejectedExecutionException {@inheritDoc}
694	+	*/
695		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
696	<	ArrayList<ForkJoinTask<T>> ts =
696	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
697		new ArrayList<ForkJoinTask<T>>(tasks.size());
698	<	for (Callable<T> c : tasks)
699	<	ts.add(new AdaptedCallable<T>(c));
700	<	invoke(new InvokeAll<T>(ts));
701	<	return (List<Future<T>>) (List) ts;
698	>	for (Callable<T> task : tasks)
699	>	forkJoinTasks.add(ForkJoinTask.adapt(task));
700	>	invoke(new InvokeAll<T>(forkJoinTasks));
701	>
702	>	@SuppressWarnings({"unchecked", "rawtypes"})
703	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
704	>	return futures;
705		}
706
707		static final class InvokeAll<T> extends RecursiveAction {
#	Line 685 | Line 729 | public class ForkJoinPool extends Abstra
729		* Returns the handler for internal worker threads that terminate
730		* due to unrecoverable errors encountered while executing tasks.
731		*
732	<	* @return the handler, or null if none
732	>	* @return the handler, or {@code null} if none
733		*/
734		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
735		Thread.UncaughtExceptionHandler h;
#	Line 706 | Line 750 | public class ForkJoinPool extends Abstra
750		* as handler.
751		*
752		* @param h the new handler
753	<	* @return the old handler, or null if none
753	>	* @return the old handler, or {@code null} if none
754		* @throws SecurityException if a security manager exists and
755		*         the caller is not permitted to modify threads
756		*         because it does not hold {@link
#	Line 754 | Line 798 | public class ForkJoinPool extends Abstra
798		final ReentrantLock lock = this.workerLock;
799		lock.lock();
800		try {
801	<	if (!isTerminating()) {
801	>	if (isProcessingTasks()) {
802		int p = this.parallelism;
803		this.parallelism = parallelism;
804	<	if (parallelism > p)
805	<	createAndStartAddedWorkers();
806	<	else
807	<	trimSpares();
804	>	if (workers != null) {
805	>	if (parallelism > p)
806	>	createAndStartAddedWorkers();
807	>	else
808	>	trimSpares();
809	>	}
810		}
811		} finally {
812		lock.unlock();
#	Line 769 | Line 815 | public class ForkJoinPool extends Abstra
815		}
816
817		/**
818	<	* Returns the targeted number of worker threads in this pool.
818	>	* Returns the targeted parallelism level of this pool.
819		*
820	<	* @return the targeted number of worker threads in this pool
820	>	* @return the targeted parallelism level of this pool
821		*/
822		public int getParallelism() {
823		return parallelism;
#	Line 780 | Line 826 | public class ForkJoinPool extends Abstra
826		/**
827		* Returns the number of worker threads that have started but not
828		* yet terminated.  This result returned by this method may differ
829	<	* from {@code getParallelism} when threads are created to
829	>	* from {@link #getParallelism} when threads are created to
830		* maintain parallelism when others are cooperatively blocked.
831		*
832		* @return the number of worker threads
#	Line 791 | Line 837 | public class ForkJoinPool extends Abstra
837
838		/**
839		* Returns the maximum number of threads allowed to exist in the
840	<	* pool, even if there are insufficient unblocked running threads.
840	>	* pool. Unless set using {@link #setMaximumPoolSize}, the
841	>	* maximum is an implementation-defined value designed only to
842	>	* prevent runaway growth.
843		*
844		* @return the maximum
845		*/
#	Line 801 | Line 849 | public class ForkJoinPool extends Abstra
849
850		/**
851		* Sets the maximum number of threads allowed to exist in the
852	<	* pool, even if there are insufficient unblocked running threads.
853	<	* Setting this value has no effect on current pool size. It
854	<	* controls construction of new threads.
852	>	* pool. The given value should normally be greater than or equal
853	>	* to the {@link #getParallelism parallelism} level. Setting this
854	>	* value has no effect on current pool size. It controls
855	>	* construction of new threads.
856		*
857	<	* @throws IllegalArgumentException if negative or greater then
857	>	* @throws IllegalArgumentException if negative or greater than
858		* internal implementation limit
859		*/
860		public void setMaximumPoolSize(int newMax) {
#	Line 816 | Line 865 | public class ForkJoinPool extends Abstra
865
866
867		/**
868	<	* Returns true if this pool dynamically maintains its target
869	<	* parallelism level. If false, new threads are added only to
870	<	* avoid possible starvation.
822	<	* This setting is by default true.
868	>	* Returns {@code true} if this pool dynamically maintains its
869	>	* target parallelism level. If false, new threads are added only
870	>	* to avoid possible starvation.  This setting is by default true.
871		*
872	<	* @return true if maintains parallelism
872	>	* @return {@code true} if maintains parallelism
873		*/
874		public boolean getMaintainsParallelism() {
875		return maintainsParallelism;
#	Line 832 | Line 880 | public class ForkJoinPool extends Abstra
880		* parallelism level. If false, new threads are added only to
881		* avoid possible starvation.
882		*
883	<	* @param enable true to maintains parallelism
883	>	* @param enable {@code true} to maintain parallelism
884		*/
885		public void setMaintainsParallelism(boolean enable) {
886		maintainsParallelism = enable;
#	Line 843 | Line 891 | public class ForkJoinPool extends Abstra
891		* tasks that are never joined. This mode may be more appropriate
892		* than default locally stack-based mode in applications in which
893		* worker threads only process asynchronous tasks.  This method is
894	<	* designed to be invoked only when pool is quiescent, and
894	>	* designed to be invoked only when the pool is quiescent, and
895		* typically only before any tasks are submitted. The effects of
896		* invocations at other times may be unpredictable.
897		*
898	<	* @param async if true, use locally FIFO scheduling
898	>	* @param async if {@code true}, use locally FIFO scheduling
899		* @return the previous mode
900	+	* @see #getAsyncMode
901		*/
902		public boolean setAsyncMode(boolean async) {
903		boolean oldMode = locallyFifo;
#	Line 865 | Line 914 | public class ForkJoinPool extends Abstra
914		}
915
916		/**
917	<	* Returns true if this pool uses local first-in-first-out
917	>	* Returns {@code true} if this pool uses local first-in-first-out
918		* scheduling mode for forked tasks that are never joined.
919		*
920	<	* @return true if this pool uses async mode
920	>	* @return {@code true} if this pool uses async mode
921	>	* @see #setAsyncMode
922		*/
923		public boolean getAsyncMode() {
924		return locallyFifo;
#	Line 909 | Line 959 | public class ForkJoinPool extends Abstra
959		}
960
961		/**
962	<	* Returns true if all worker threads are currently idle. An idle
963	<	* worker is one that cannot obtain a task to execute because none
964	<	* are available to steal from other threads, and there are no
965	<	* pending submissions to the pool. This method is conservative;
966	<	* it might not return true immediately upon idleness of all
967	<	* threads, but will eventually become true if threads remain
968	<	* inactive.
962	>	* Returns {@code true} if all worker threads are currently idle.
963	>	* An idle worker is one that cannot obtain a task to execute
964	>	* because none are available to steal from other threads, and
965	>	* there are no pending submissions to the pool. This method is
966	>	* conservative; it might not return {@code true} immediately upon
967	>	* idleness of all threads, but will eventually become true if
968	>	* threads remain inactive.
969		*
970	<	* @return true if all threads are currently idle
970	>	* @return {@code true} if all threads are currently idle
971		*/
972		public boolean isQuiescent() {
973		return activeCountOf(runControl) == 0;
#	Line 972 | Line 1022 | public class ForkJoinPool extends Abstra
1022		}
1023
1024		/**
1025	<	* Returns an estimate of the number tasks submitted to this pool
1026	<	* that have not yet begun executing. This method takes time
1025	>	* Returns an estimate of the number of tasks submitted to this
1026	>	* pool that have not yet begun executing.  This method takes time
1027		* proportional to the number of submissions.
1028		*
1029		* @return the number of queued submissions
#	Line 983 | Line 1033 | public class ForkJoinPool extends Abstra
1033		}
1034
1035		/**
1036	<	* Returns true if there are any tasks submitted to this pool
1037	<	* that have not yet begun executing.
1036	>	* Returns {@code true} if there are any tasks submitted to this
1037	>	* pool that have not yet begun executing.
1038		*
1039		* @return {@code true} if there are any queued submissions
1040		*/
#	Line 997 | Line 1047 | public class ForkJoinPool extends Abstra
1047		* available.  This method may be useful in extensions to this
1048		* class that re-assign work in systems with multiple pools.
1049		*
1050	<	* @return the next submission, or null if none
1050	>	* @return the next submission, or {@code null} if none
1051		*/
1052		protected ForkJoinTask<?> pollSubmission() {
1053		return submissionQueue.poll();
#	Line 1007 | Line 1057 | public class ForkJoinPool extends Abstra
1057		* Removes all available unexecuted submitted and forked tasks
1058		* from scheduling queues and adds them to the given collection,
1059		* without altering their execution status. These may include
1060	<	* artificially generated or wrapped tasks. This method is designed
1061	<	* to be invoked only when the pool is known to be
1060	>	* artificially generated or wrapped tasks. This method is
1061	>	* designed to be invoked only when the pool is known to be
1062		* quiescent. Invocations at other times may not remove all
1063		* tasks. A failure encountered while attempting to add elements
1064		* to collection {@code c} may result in elements being in
#	Line 1020 | Line 1070 | public class ForkJoinPool extends Abstra
1070		* @param c the collection to transfer elements into
1071		* @return the number of elements transferred
1072		*/
1073	<	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
1073	>	protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {
1074		int n = submissionQueue.drainTo(c);
1075		ForkJoinWorkerThread[] ws = workers;
1076		if (ws != null) {
#	Line 1060 | Line 1110 | public class ForkJoinPool extends Abstra
1110		}
1111
1112		private static String runStateToString(int rs) {
1113	<	switch(rs) {
1113	>	switch (rs) {
1114		case RUNNING: return "Running";
1115		case SHUTDOWN: return "Shutting down";
1116		case TERMINATING: return "Terminating";
#	Line 1086 | Line 1136 | public class ForkJoinPool extends Abstra
1136		public void shutdown() {
1137		checkPermission();
1138		transitionRunStateTo(SHUTDOWN);
1139	<	if (canTerminateOnShutdown(runControl))
1139	>	if (canTerminateOnShutdown(runControl)) {
1140	>	if (workers == null) { // shutting down before workers created
1141	>	final ReentrantLock lock = this.workerLock;
1142	>	lock.lock();
1143	>	try {
1144	>	if (workers == null) {
1145	>	terminate();
1146	>	transitionRunStateTo(TERMINATED);
1147	>	termination.signalAll();
1148	>	}
1149	>	} finally {
1150	>	lock.unlock();
1151	>	}
1152	>	}
1153		terminateOnShutdown();
1154	+	}
1155		}
1156
1157		/**
1158	<	* Attempts to stop all actively executing tasks, and cancels all
1159	<	* waiting tasks.  Tasks that are in the process of being
1160	<	* submitted or executed concurrently during the course of this
1161	<	* method may or may not be rejected. Unlike some other executors,
1162	<	* this method cancels rather than collects non-executed tasks
1163	<	* upon termination, so always returns an empty list. However, you
1164	<	* can use method {@code drainTasksTo} before invoking this
1165	<	* method to transfer unexecuted tasks to another collection.
1158	>	* Attempts to cancel and/or stop all tasks, and reject all
1159	>	* subsequently submitted tasks.  Tasks that are in the process of
1160	>	* being submitted or executed concurrently during the course of
1161	>	* this method may or may not be rejected. This method cancels
1162	>	* both existing and unexecuted tasks, in order to permit
1163	>	* termination in the presence of task dependencies. So the method
1164	>	* always returns an empty list (unlike the case for some other
1165	>	* Executors).
1166		*
1167		* @return an empty list
1168		* @throws SecurityException if a security manager exists and
#	Line 1123 | Line 1187 | public class ForkJoinPool extends Abstra
1187
1188		/**
1189		* Returns {@code true} if the process of termination has
1190	<	* commenced but possibly not yet completed.
1190	>	* commenced but not yet completed.  This method may be useful for
1191	>	* debugging. A return of {@code true} reported a sufficient
1192	>	* period after shutdown may indicate that submitted tasks have
1193	>	* ignored or suppressed interruption, causing this executor not
1194	>	* to properly terminate.
1195		*
1196	<	* @return {@code true} if terminating
1196	>	* @return {@code true} if terminating but not yet terminated
1197		*/
1198		public boolean isTerminating() {
1199	<	return runStateOf(runControl) >= TERMINATING;
1199	>	return runStateOf(runControl) == TERMINATING;
1200		}
1201
1202		/**
#	Line 1141 | Line 1209 | public class ForkJoinPool extends Abstra
1209		}
1210
1211		/**
1212	+	* Returns true if pool is not terminating or terminated.
1213	+	* Used internally to suppress execution when terminating.
1214	+	*/
1215	+	final boolean isProcessingTasks() {
1216	+	return runStateOf(runControl) < TERMINATING;
1217	+	}
1218	+
1219	+	/**
1220		* Blocks until all tasks have completed execution after a shutdown
1221		* request, or the timeout occurs, or the current thread is
1222		* interrupted, whichever happens first.
#	Line 1194 | Line 1270 | public class ForkJoinPool extends Abstra
1270		transitionRunStateTo(TERMINATED);
1271		termination.signalAll();
1272		}
1273	<	else if (!isTerminating()) {
1273	>	else if (isProcessingTasks()) {
1274		tryShrinkWorkerArray();
1275		tryResumeSpare(true); // allow replacement
1276		}
#	Line 1304 | Line 1380 | public class ForkJoinPool extends Abstra
1380		}
1381		}
1382
1307	–
1383		/*
1384		* Nodes for event barrier to manage idle threads.  Queue nodes
1385		* are basic Treiber stack nodes, also used for spare stack.
#	Line 1328 | Line 1403 | public class ForkJoinPool extends Abstra
1403		* handling: Method signalWork returns without advancing count if
1404		* the queue appears to be empty.  This would ordinarily result in
1405		* races causing some queued waiters not to be woken up. To avoid
1406	<	* this, the first worker enqueued in method sync (see
1407	<	* syncIsReleasable) rescans for tasks after being enqueued, and
1408	<	* helps signal if any are found. This works well because the
1409	<	* worker has nothing better to do, and so might as well help
1410	<	* alleviate the overhead and contention on the threads actually
1411	<	* doing work.  Also, since event counts increments on task
1412	<	* availability exist to maintain liveness (rather than to force
1413	<	* refreshes etc), it is OK for callers to exit early if
1339	<	* contending with another signaller.
1406	>	* this, the first worker enqueued in method sync rescans for
1407	>	* tasks after being enqueued, and helps signal if any are
1408	>	* found. This works well because the worker has nothing better to
1409	>	* do, and so might as well help alleviate the overhead and
1410	>	* contention on the threads actually doing work.  Also, since
1411	>	* event counts increments on task availability exist to maintain
1412	>	* liveness (rather than to force refreshes etc), it is OK for
1413	>	* callers to exit early if contending with another signaller.
1414		*/
1415		static final class WaitQueueNode {
1416		WaitQueueNode next; // only written before enqueued
#	Line 1349 | Line 1423 | public class ForkJoinPool extends Abstra
1423		}
1424
1425		/**
1426	<	* Wakes up waiter, returning false if known to already
1426	>	* Wakes up waiter, also clearing thread field
1427		*/
1428	<	boolean signal() {
1428	>	void signal() {
1429		ForkJoinWorkerThread t = thread;
1430	<	if (t == null)
1431	<	return false;
1432	<	thread = null;
1359	<	LockSupport.unpark(t);
1360	<	return true;
1361	<	}
1362	<
1363	<	/**
1364	<	* Awaits release on sync.
1365	<	*/
1366	<	void awaitSyncRelease(ForkJoinPool p) {
1367	<	while (thread != null && !p.syncIsReleasable(this))
1368	<	LockSupport.park(this);
1369	<	}
1370	<
1371	<	/**
1372	<	* Awaits resumption as spare.
1373	<	*/
1374	<	void awaitSpareRelease() {
1375	<	while (thread != null) {
1376	<	if (!Thread.interrupted())
1377	<	LockSupport.park(this);
1430	>	if (t != null) {
1431	>	thread = null;
1432	>	LockSupport.unpark(t);
1433		}
1434		}
1435		}
#	Line 1383 | Line 1438 | public class ForkJoinPool extends Abstra
1438		* Ensures that no thread is waiting for count to advance from the
1439		* current value of eventCount read on entry to this method, by
1440		* releasing waiting threads if necessary.
1386	–	*
1387	–	* @return the count
1441		*/
1442	<	final long ensureSync() {
1442	>	final void ensureSync() {
1443		long c = eventCount;
1444		WaitQueueNode q;
1445		while ((q = syncStack) != null && q.count < c) {
#	Line 1397 | Line 1450 | public class ForkJoinPool extends Abstra
1450		break;
1451		}
1452		}
1400	–	return c;
1453		}
1454
1455		/**
#	Line 1412 | Line 1464 | public class ForkJoinPool extends Abstra
1464		/**
1465		* Signals threads waiting to poll a task. Because method sync
1466		* rechecks availability, it is OK to only proceed if queue
1467	<	* appears to be non-empty, and OK to skip under contention to
1468	<	* increment count (since some other thread succeeded).
1467	>	* appears to be non-empty, and OK if CAS to increment count
1468	>	* fails (since some other thread succeeded).
1469		*/
1470		final void signalWork() {
1471	<	long c;
1472	<	WaitQueueNode q;
1473	<	if (syncStack != null &&
1474	<	casEventCount(c = eventCount, c+1) &&
1475	<	(((q = syncStack) != null && q.count <= c) &&
1476	<	(!casBarrierStack(q, q.next) || !q.signal())))
1477	<	ensureSync();
1471	>	if (syncStack != null) {
1472	>	long c = eventCount;
1473	>	casEventCount(c, c+1);
1474	>	WaitQueueNode q = syncStack;
1475	>	if (q != null && q.count <= c) {
1476	>	if (casBarrierStack(q, q.next))
1477	>	q.signal();
1478	>	else
1479	>	ensureSync(); // awaken all on contention
1480	>	}
1481	>	}
1482		}
1483
1484		/**
1485	<	* Waits until event count advances from last value held by
1486	<	* caller, or if excess threads, caller is resumed as spare, or
1485	>	* Possibly blocks until event count advances from last value held
1486	>	* by caller, or if excess threads, caller is resumed as spare, or
1487		* caller or pool is terminating. Updates caller's event on exit.
1488		*
1489		* @param w the calling worker thread
#	Line 1435 | Line 1491 | public class ForkJoinPool extends Abstra
1491		final void sync(ForkJoinWorkerThread w) {
1492		updateStealCount(w); // Transfer w's count while it is idle
1493
1494	<	while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) {
1494	>	if (!w.isShutdown() && isProcessingTasks() && !suspendIfSpare(w)) {
1495		long prev = w.lastEventCount;
1496		WaitQueueNode node = null;
1497		WaitQueueNode h;
1498	<	while (eventCount == prev &&
1498	>	long c;
1499	>	while ((c = eventCount) == prev &&
1500		((h = syncStack) == null || h.count == prev)) {
1501		if (node == null)
1502		node = new WaitQueueNode(prev, w);
1503		if (casBarrierStack(node.next = h, node)) {
1504	<	node.awaitSyncRelease(this);
1504	>	if (!Thread.interrupted() &&
1505	>	node.thread != null &&
1506	>	eventCount == prev &&
1507	>	(h != null || // cover signalWork race
1508	>	(!ForkJoinWorkerThread.hasQueuedTasks(workers) &&
1509	>	eventCount == prev)))
1510	>	LockSupport.park(this);
1511	>	c = eventCount;
1512	>	if (node.thread != null) { // help signal if not unparked
1513	>	node.thread = null;
1514	>	if (c == prev)
1515	>	casEventCount(prev, prev + 1);
1516	>	}
1517		break;
1518		}
1519		}
1520	<	long ec = ensureSync();
1521	<	if (ec != prev) {
1453	<	w.lastEventCount = ec;
1454	<	break;
1455	<	}
1456	<	}
1457	<	}
1458	<
1459	<	/**
1460	<	* Returns true if worker waiting on sync can proceed:
1461	<	*  - on signal (thread == null)
1462	<	*  - on event count advance (winning race to notify vs signaller)
1463	<	*  - on interrupt
1464	<	*  - if the first queued node, we find work available
1465	<	* If node was not signalled and event count not advanced on exit,
1466	<	* then we also help advance event count.
1467	<	*
1468	<	* @return true if node can be released
1469	<	*/
1470	<	final boolean syncIsReleasable(WaitQueueNode node) {
1471	<	long prev = node.count;
1472	<	if (!Thread.interrupted() && node.thread != null &&
1473	<	(node.next != null ||
1474	<	!ForkJoinWorkerThread.hasQueuedTasks(workers)) &&
1475	<	eventCount == prev)
1476	<	return false;
1477	<	if (node.thread != null) {
1478	<	node.thread = null;
1479	<	long ec = eventCount;
1480	<	if (prev <= ec) // help signal
1481	<	casEventCount(ec, ec+1);
1520	>	w.lastEventCount = c;
1521	>	ensureSync();
1522		}
1483	–	return true;
1523		}
1524
1525		/**
1526	<	* Returns true if a new sync event occurred since last call to
1527	<	* sync or this method, if so, updating caller's count.
1526	>	* Returns {@code true} if a new sync event occurred since last
1527	>	* call to sync or this method, if so, updating caller's count.
1528		*/
1529		final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1530	<	long lc = w.lastEventCount;
1531	<	long ec = ensureSync();
1532	<	if (ec == lc)
1533	<	return false;
1534	<	w.lastEventCount = ec;
1535	<	return true;
1530	>	long wc = w.lastEventCount;
1531	>	long c = eventCount;
1532	>	if (wc != c)
1533	>	w.lastEventCount = c;
1534	>	ensureSync();
1535	>	return wc != c || wc != eventCount;
1536		}
1537
1538		//  Parallelism maintenance
#	Line 1535 | Line 1574 | public class ForkJoinPool extends Abstra
1574		while (spareStack == null || !tryResumeSpare(dec)) {
1575		int counts = workerCounts;
1576		if (dec || (dec = casWorkerCounts(counts, --counts))) {
1538	–	// CAS cheat
1577		if (!needSpare(counts, maintainParallelism))
1578		break;
1579		if (joinMe.status < 0)
#	Line 1569 | Line 1607 | public class ForkJoinPool extends Abstra
1607		}
1608
1609		/**
1610	<	* Returns true if a spare thread appears to be needed.  If
1611	<	* maintaining parallelism, returns true when the deficit in
1610	>	* Returns {@code true} if a spare thread appears to be needed.
1611	>	* If maintaining parallelism, returns true when the deficit in
1612		* running threads is more than the surplus of total threads, and
1613		* there is apparently some work to do.  This self-limiting rule
1614		* means that the more threads that have already been added, the
#	Line 1640 | Line 1678 | public class ForkJoinPool extends Abstra
1678		for (k = 0; k < len && ws[k] != null; ++k)
1679		;
1680		}
1681	<	if (k < len && !isTerminating() && (w = createWorker(k)) != null) {
1681	>	if (k < len && isProcessingTasks() && (w = createWorker(k)) != null) {
1682		ws[k] = w;
1683		w.start();
1684		}
#	Line 1660 | Line 1698 | public class ForkJoinPool extends Abstra
1698		*/
1699		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
1700		WaitQueueNode node = null;
1701	<	int s;
1702	<	while (parallelism < runningCountOf(s = workerCounts)) {
1701	>	for (;;) {
1702	>	int s = workerCounts;
1703	>	int rc = runningCountOf(s);
1704	>	int tc = totalCountOf(s);
1705	>	int ps = parallelism;
1706	>	// use tc as bound if rc transiently out of sync
1707	>	if (tc <= ps || rc <= ps)
1708	>	return false; // not a spare
1709		if (node == null)
1710		node = new WaitQueueNode(0, w);
1711	<	if (casWorkerCounts(s, s-1)) { // representation-dependent
1712	<	// push onto stack
1669	<	do {} while (!casSpareStack(node.next = spareStack, node));
1670	<	// block until released by resumeSpare
1671	<	node.awaitSpareRelease();
1672	<	return true;
1673	<	}
1711	>	if (casWorkerCounts(s, workerCountsFor(tc, rc - 1)))
1712	>	break;
1713		}
1714	<	return false;
1714	>	// push onto stack
1715	>	do {} while (!casSpareStack(node.next = spareStack, node));
1716	>	// block until released by resumeSpare
1717	>	while (!Thread.interrupted() && node.thread != null)
1718	>	LockSupport.park(this);
1719	>	return true;
1720		}
1721
1722		/**
#	Line 1738 | Line 1782 | public class ForkJoinPool extends Abstra
1782
1783		/**
1784		* Interface for extending managed parallelism for tasks running
1785	<	* in ForkJoinPools. A ManagedBlocker provides two methods.
1786	<	* Method {@code isReleasable} must return true if blocking is not
1787	<	* necessary. Method {@code block} blocks the current thread if
1788	<	* necessary (perhaps internally invoking {@code isReleasable}
1789	<	* before actually blocking.).
1785	>	* in {@link ForkJoinPool}s.
1786	>	*
1787	>	* <p>A {@code ManagedBlocker} provides two methods.
1788	>	* Method {@code isReleasable} must return {@code true} if
1789	>	* blocking is not necessary. Method {@code block} blocks the
1790	>	* current thread if necessary (perhaps internally invoking
1791	>	* {@code isReleasable} before actually blocking).
1792		*
1793		* <p>For example, here is a ManagedBlocker based on a
1794		* ReentrantLock:
#	Line 1766 | Line 1812 | public class ForkJoinPool extends Abstra
1812		* Possibly blocks the current thread, for example waiting for
1813		* a lock or condition.
1814		*
1815	<	* @return true if no additional blocking is necessary (i.e.,
1816	<	* if isReleasable would return true)
1815	>	* @return {@code true} if no additional blocking is necessary
1816	>	* (i.e., if isReleasable would return true)
1817		* @throws InterruptedException if interrupted while waiting
1818		* (the method is not required to do so, but is allowed to)
1819		*/
1820		boolean block() throws InterruptedException;
1821
1822		/**
1823	<	* Returns true if blocking is unnecessary.
1823	>	* Returns {@code true} if blocking is unnecessary.
1824		*/
1825		boolean isReleasable();
1826		}
1827
1828		/**
1829		* Blocks in accord with the given blocker.  If the current thread
1830	<	* is a ForkJoinWorkerThread, this method possibly arranges for a
1831	<	* spare thread to be activated if necessary to ensure parallelism
1832	<	* while the current thread is blocked.  If
1833	<	* {@code maintainParallelism} is true and the pool supports
1834	<	* it ({@link #getMaintainsParallelism}), this method attempts to
1835	<	* maintain the pool's nominal parallelism. Otherwise it activates
1836	<	* a thread only if necessary to avoid complete starvation. This
1837	<	* option may be preferable when blockages use timeouts, or are
1838	<	* almost always brief.
1830	>	* is a {@link ForkJoinWorkerThread}, this method possibly
1831	>	* arranges for a spare thread to be activated if necessary to
1832	>	* ensure parallelism while the current thread is blocked.
1833	>	*
1834	>	* <p>If {@code maintainParallelism} is {@code true} and the pool
1835	>	* supports it ({@link #getMaintainsParallelism}), this method
1836	>	* attempts to maintain the pool's nominal parallelism. Otherwise
1837	>	* it activates a thread only if necessary to avoid complete
1838	>	* starvation. This option may be preferable when blockages use
1839	>	* timeouts, or are almost always brief.
1840		*
1841	<	* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1842	<	* equivalent to
1841	>	* <p>If the caller is not a {@link ForkJoinTask}, this method is
1842	>	* behaviorally equivalent to
1843		*  <pre> {@code
1844		* while (!blocker.isReleasable())
1845		*   if (blocker.block())
1846		*     return;
1847		* }</pre>
1848	<	* If the caller is a ForkJoinTask, then the pool may first
1849	<	* be expanded to ensure parallelism, and later adjusted.
1848	>	*
1849	>	* If the caller is a {@code ForkJoinTask}, then the pool may
1850	>	* first be expanded to ensure parallelism, and later adjusted.
1851		*
1852		* @param blocker the blocker
1853	<	* @param maintainParallelism if true and supported by this pool,
1854	<	* attempt to maintain the pool's nominal parallelism; otherwise
1855	<	* activate a thread only if necessary to avoid complete
1856	<	* starvation.
1853	>	* @param maintainParallelism if {@code true} and supported by
1854	>	* this pool, attempt to maintain the pool's nominal parallelism;
1855	>	* otherwise activate a thread only if necessary to avoid
1856	>	* complete starvation.
1857		* @throws InterruptedException if blocker.block did so
1858		*/
1859		public static void managedBlock(ManagedBlocker blocker,
#	Line 1831 | Line 1879 | public class ForkJoinPool extends Abstra
1879		do {} while (!blocker.isReleasable() && !blocker.block());
1880		}
1881
1882	<	// AbstractExecutorService overrides
1882	>	// AbstractExecutorService overrides.  These rely on undocumented
1883	>	// fact that ForkJoinTask.adapt returns ForkJoinTasks that also
1884	>	// implement RunnableFuture.
1885
1886		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1887	<	return new AdaptedRunnable<T>(runnable, value);
1887	>	return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value);
1888		}
1889
1890		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1891	<	return new AdaptedCallable<T>(callable);
1891	>	return (RunnableFuture<T>) ForkJoinTask.adapt(callable);
1892		}
1893
1894	+	// Unsafe mechanics
1895
1896	<	// Temporary Unsafe mechanics for preliminary release
1897	<	private static Unsafe getUnsafe() throws Throwable {
1898	<	try {
1899	<	return Unsafe.getUnsafe();
1900	<	} catch (SecurityException se) {
1901	<	try {
1902	<	return java.security.AccessController.doPrivileged
1903	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1904	<	public Unsafe run() throws Exception {
1905	<	return getUnsafePrivileged();
1906	<	}});
1856	<	} catch (java.security.PrivilegedActionException e) {
1857	<	throw e.getCause();
1858	<	}
1859	<	}
1860	<	}
1861	<
1862	<	private static Unsafe getUnsafePrivileged()
1863	<	throws NoSuchFieldException, IllegalAccessException {
1864	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1865	<	f.setAccessible(true);
1866	<	return (Unsafe) f.get(null);
1867	<	}
1868	<
1869	<	private static long fieldOffset(String fieldName)
1870	<	throws NoSuchFieldException {
1871	<	return UNSAFE.objectFieldOffset
1872	<	(ForkJoinPool.class.getDeclaredField(fieldName));
1873	<	}
1874	<
1875	<	static final Unsafe UNSAFE;
1876	<	static final long eventCountOffset;
1877	<	static final long workerCountsOffset;
1878	<	static final long runControlOffset;
1879	<	static final long syncStackOffset;
1880	<	static final long spareStackOffset;
1881	<
1882	<	static {
1883	<	try {
1884	<	UNSAFE = getUnsafe();
1885	<	eventCountOffset = fieldOffset("eventCount");
1886	<	workerCountsOffset = fieldOffset("workerCounts");
1887	<	runControlOffset = fieldOffset("runControl");
1888	<	syncStackOffset = fieldOffset("syncStack");
1889	<	spareStackOffset = fieldOffset("spareStack");
1890	<	} catch (Throwable e) {
1891	<	throw new RuntimeException("Could not initialize intrinsics", e);
1892	<	}
1893	<	}
1896	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1897	>	private static final long eventCountOffset =
1898	>	objectFieldOffset("eventCount", ForkJoinPool.class);
1899	>	private static final long workerCountsOffset =
1900	>	objectFieldOffset("workerCounts", ForkJoinPool.class);
1901	>	private static final long runControlOffset =
1902	>	objectFieldOffset("runControl", ForkJoinPool.class);
1903	>	private static final long syncStackOffset =
1904	>	objectFieldOffset("syncStack",ForkJoinPool.class);
1905	>	private static final long spareStackOffset =
1906	>	objectFieldOffset("spareStack", ForkJoinPool.class);
1907
1908		private boolean casEventCount(long cmp, long val) {
1909		return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
#	Line 1907 | Line 1920 | public class ForkJoinPool extends Abstra
1920		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1921		return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1922		}
1923	+
1924	+	private static long objectFieldOffset(String field, Class<?> klazz) {
1925	+	try {
1926	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1927	+	} catch (NoSuchFieldException e) {
1928	+	// Convert Exception to corresponding Error
1929	+	NoSuchFieldError error = new NoSuchFieldError(field);
1930	+	error.initCause(e);
1931	+	throw error;
1932	+	}
1933	+	}
1934	+
1935	+	/**
1936	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1937	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1938	+	* into a jdk.
1939	+	*
1940	+	* @return a sun.misc.Unsafe
1941	+	*/
1942	+	private static sun.misc.Unsafe getUnsafe() {
1943	+	try {
1944	+	return sun.misc.Unsafe.getUnsafe();
1945	+	} catch (SecurityException se) {
1946	+	try {
1947	+	return java.security.AccessController.doPrivileged
1948	+	(new java.security
1949	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1950	+	public sun.misc.Unsafe run() throws Exception {
1951	+	java.lang.reflect.Field f = sun.misc
1952	+	.Unsafe.class.getDeclaredField("theUnsafe");
1953	+	f.setAccessible(true);
1954	+	return (sun.misc.Unsafe) f.get(null);
1955	+	}});
1956	+	} catch (java.security.PrivilegedActionException e) {
1957	+	throw new RuntimeException("Could not initialize intrinsics",
1958	+	e.getCause());
1959	+	}
1960	+	}
1961	+	}
1962		}

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