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Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.7 by jsr166, Mon Jul 20 21:45:06 2009 UTC vs.
Revision 1.32 by jsr166, Thu Jul 30 22:05:19 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
23	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.
24	>	* A 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
27		* submitted tasks. Otherwise, use would not usually outweigh the
#	Line 27 | Line 34 | import java.lang.reflect.*;
34		* (eventually blocking if none exist). This makes them efficient when
35		* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
36		* as the mixed execution of some plain Runnable- or Callable- based
37	<	* activities along with ForkJoinTasks. When setting
38	<	* <tt>setAsyncMode</tt>, a ForkJoinPools may also be appropriate for
39	<	* use with fine-grained tasks that are never joined. Otherwise, other
40	<	* ExecutorService implementations are typically more appropriate
41	<	* choices.
37	>	* activities along with ForkJoinTasks. When setting {@linkplain
38	>	* #setAsyncMode async mode}, a ForkJoinPool may also be appropriate
39	>	* for use with fine-grained tasks that are never joined. Otherwise,
40	>	* other ExecutorService implementations are typically more
41	>	* appropriate choices.
42		*
43		* <p>A ForkJoinPool may be constructed with a given parallelism level
44		* (target pool size), which it attempts to maintain by dynamically
45		* adding, suspending, or resuming threads, even if some tasks are
46		* waiting to join others. However, no such adjustments are performed
47		* in the face of blocked IO or other unmanaged synchronization. The
48	<	* nested <code>ManagedBlocker</code> interface enables extension of
48	>	* nested {@link ManagedBlocker} interface enables extension of
49		* the kinds of synchronization accommodated.  The target parallelism
50	<	* level may also be changed dynamically (<code>setParallelism</code>)
50	>	* level may also be changed dynamically ({@link #setParallelism})
51		* and thread construction can be limited using methods
52	<	* <code>setMaximumPoolSize</code> and/or
53	<	* <code>setMaintainsParallelism</code>.
52	>	* {@link #setMaximumPoolSize} and/or
53	>	* {@link #setMaintainsParallelism}.
54		*
55		* <p>In addition to execution and lifecycle control methods, this
56		* class provides status check methods (for example
57	<	* <code>getStealCount</code>) that are intended to aid in developing,
57	>	* {@link #getStealCount}) that are intended to aid in developing,
58		* tuning, and monitoring fork/join applications. Also, method
59	<	* <code>toString</code> returns indications of pool state in a
59	>	* {@link #toString} returns indications of pool state in a
60		* convenient form for informal monitoring.
61		*
62		* <p><b>Implementation notes</b>: This implementation restricts the
63		* maximum number of running threads to 32767. Attempts to create
64		* pools with greater than the maximum result in
65		* IllegalArgumentExceptions.
66	+	*
67	+	* @since 1.7
68	+	* @author Doug Lea
69		*/
70		public class ForkJoinPool extends AbstractExecutorService {
71
#	Line 81 | Line 91 | public class ForkJoinPool extends Abstra
91		* Returns a new worker thread operating in the given pool.
92		*
93		* @param pool the pool this thread works in
94	<	* @throws NullPointerException if pool is null;
94	>	* @throws NullPointerException if pool is null
95		*/
96		public ForkJoinWorkerThread newThread(ForkJoinPool pool);
97		}
98
99		/**
100	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
100	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
101		* new ForkJoinWorkerThread.
102		*/
103		static class  DefaultForkJoinWorkerThreadFactory
#	Line 153 | Line 163 | public class ForkJoinPool extends Abstra
163
164		/**
165		* The uncaught exception handler used when any worker
166	<	* abrupty terminates
166	>	* abruptly terminates
167		*/
168		private Thread.UncaughtExceptionHandler ueh;
169
#	Line 181 | Line 191 | public class ForkJoinPool extends Abstra
191		private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue;
192
193		/**
194	<	* Head of Treiber stack for barrier sync. See below for explanation
194	>	* Head of Treiber stack for barrier sync. See below for explanation.
195		*/
196		private volatile WaitQueueNode syncStack;
197
#	Line 216 | Line 226 | public class ForkJoinPool extends Abstra
226		* threads, packed into one int to ensure consistent snapshot when
227		* making decisions about creating and suspending spare
228		* threads. Updated only by CAS.  Note: CASes in
229	<	* updateRunningCount and preJoin running active count is in low
230	<	* word, so need to be modified if this changes
229	>	* updateRunningCount and preJoin assume that running active count
230	>	* is in low word, so need to be modified if this changes.
231		*/
232		private volatile int workerCounts;
233
#	Line 226 | Line 236 | public class ForkJoinPool extends Abstra
236		private static int workerCountsFor(int t, int r) { return (t << 16) + r; }
237
238		/**
239	<	* Add delta (which may be negative) to running count.  This must
239	>	* Adds delta (which may be negative) to running count.  This must
240		* be called before (with negative arg) and after (with positive)
241	<	* any managed synchronization (i.e., mainly, joins)
241	>	* any managed synchronization (i.e., mainly, joins).
242	>	*
243		* @param delta the number to add
244		*/
245		final void updateRunningCount(int delta) {
246		int s;
247	<	do;while (!casWorkerCounts(s = workerCounts, s + delta));
247	>	do {} while (!casWorkerCounts(s = workerCounts, s + delta));
248		}
249
250		/**
251	<	* Add delta (which may be negative) to both total and running
251	>	* Adds delta (which may be negative) to both total and running
252		* count.  This must be called upon creation and termination of
253		* worker threads.
254	+	*
255		* @param delta the number to add
256		*/
257		private void updateWorkerCount(int delta) {
258		int d = delta + (delta << 16); // add to both lo and hi parts
259		int s;
260	<	do;while (!casWorkerCounts(s = workerCounts, s + d));
260	>	do {} while (!casWorkerCounts(s = workerCounts, s + d));
261		}
262
263		/**
#	Line 271 | Line 283 | public class ForkJoinPool extends Abstra
283		private static int runControlFor(int r, int a)   { return (r << 16) + a; }
284
285		/**
286	<	* Try incrementing active count; fail on contention. Called by
287	<	* workers before/during executing tasks.
288	<	* @return true on success;
286	>	* Tries incrementing active count; fails on contention.
287	>	* Called by workers before/during executing tasks.
288	>	*
289	>	* @return true on success
290		*/
291		final boolean tryIncrementActiveCount() {
292		int c = runControl;
#	Line 281 | Line 294 | public class ForkJoinPool extends Abstra
294		}
295
296		/**
297	<	* Try decrementing active count; fail on contention.
298	<	* Possibly trigger termination on success
297	>	* Tries decrementing active count; fails on contention.
298	>	* Possibly triggers termination on success.
299		* Called by workers when they can't find tasks.
300	+	*
301		* @return true on success
302		*/
303		final boolean tryDecrementActiveCount() {
#	Line 297 | Line 311 | public class ForkJoinPool extends Abstra
311		}
312
313		/**
314	<	* Return true if argument represents zero active count and
315	<	* nonzero runstate, which is the triggering condition for
314	>	* Returns {@code true} if argument represents zero active count
315	>	* and nonzero runstate, which is the triggering condition for
316		* terminating on shutdown.
317		*/
318		private static boolean canTerminateOnShutdown(int c) {
319	<	return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit
319	>	// i.e. least bit is nonzero runState bit
320	>	return ((c & -c) >>> 16) != 0;
321		}
322
323		/**
#	Line 328 | Line 343 | public class ForkJoinPool extends Abstra
343
344		/**
345		* Creates a ForkJoinPool with a pool size equal to the number of
346	<	* processors available on the system and using the default
347	<	* ForkJoinWorkerThreadFactory,
346	>	* processors available on the system, using the default
347	>	* ForkJoinWorkerThreadFactory.
348	>	*
349		* @throws SecurityException if a security manager exists and
350		*         the caller is not permitted to modify threads
351		*         because it does not hold {@link
352	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
352	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
353		*/
354		public ForkJoinPool() {
355		this(Runtime.getRuntime().availableProcessors(),
#	Line 341 | Line 357 | public class ForkJoinPool extends Abstra
357		}
358
359		/**
360	<	* Creates a ForkJoinPool with the indicated parellelism level
361	<	* threads, and using the default ForkJoinWorkerThreadFactory,
360	>	* Creates a ForkJoinPool with the indicated parallelism level
361	>	* threads and using the default ForkJoinWorkerThreadFactory.
362	>	*
363		* @param parallelism the number of worker threads
364		* @throws IllegalArgumentException if parallelism less than or
365		* equal to zero
366		* @throws SecurityException if a security manager exists and
367		*         the caller is not permitted to modify threads
368		*         because it does not hold {@link
369	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
369	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
370		*/
371		public ForkJoinPool(int parallelism) {
372		this(parallelism, defaultForkJoinWorkerThreadFactory);
#	Line 358 | Line 375 | public class ForkJoinPool extends Abstra
375		/**
376		* Creates a ForkJoinPool with parallelism equal to the number of
377		* processors available on the system and using the given
378	<	* ForkJoinWorkerThreadFactory,
378	>	* ForkJoinWorkerThreadFactory.
379	>	*
380		* @param factory the factory for creating new threads
381		* @throws NullPointerException if factory is null
382		* @throws SecurityException if a security manager exists and
383		*         the caller is not permitted to modify threads
384		*         because it does not hold {@link
385	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
385	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
386		*/
387		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
388		this(Runtime.getRuntime().availableProcessors(), factory);
#	Line 376 | Line 394 | public class ForkJoinPool extends Abstra
394		* @param parallelism the targeted number of worker threads
395		* @param factory the factory for creating new threads
396		* @throws IllegalArgumentException if parallelism less than or
397	<	* equal to zero, or greater than implementation limit.
397	>	* equal to zero, or greater than implementation limit
398		* @throws NullPointerException if factory is null
399		* @throws SecurityException if a security manager exists and
400		*         the caller is not permitted to modify threads
401		*         because it does not hold {@link
402	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
402	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
403		*/
404		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
405		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 402 | Line 420 | public class ForkJoinPool extends Abstra
420		}
421
422		/**
423	<	* Create new worker using factory.
423	>	* Creates a new worker thread using factory.
424	>	*
425		* @param index the index to assign worker
426		* @return new worker, or null of factory failed
427		*/
#	Line 421 | Line 440 | public class ForkJoinPool extends Abstra
440		}
441
442		/**
443	<	* Return a good size for worker array given pool size.
443	>	* Returns a good size for worker array given pool size.
444		* Currently requires size to be a power of two.
445		*/
446	<	private static int arraySizeFor(int ps) {
447	<	return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1)));
446	>	private static int arraySizeFor(int poolSize) {
447	>	return (poolSize <= 1) ? 1 :
448	>	(1 << (32 - Integer.numberOfLeadingZeros(poolSize-1)));
449		}
450
451		/**
452	<	* Create or resize array if necessary to hold newLength.
453	<	* Call only under exlusion or lock
452	>	* Creates or resizes array if necessary to hold newLength.
453	>	* Call only under exclusion.
454	>	*
455		* @return the array
456		*/
457		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 444 | Line 465 | public class ForkJoinPool extends Abstra
465		}
466
467		/**
468	<	* Try to shrink workers into smaller array after one or more terminate
468	>	* Tries to shrink workers into smaller array after one or more terminate.
469		*/
470		private void tryShrinkWorkerArray() {
471		ForkJoinWorkerThread[] ws = workers;
#	Line 460 | Line 481 | public class ForkJoinPool extends Abstra
481		}
482
483		/**
484	<	* Initialize workers if necessary
484	>	* Initializes workers if necessary.
485		*/
486		final void ensureWorkerInitialization() {
487		ForkJoinWorkerThread[] ws = workers;
#	Line 527 | Line 548 | public class ForkJoinPool extends Abstra
548		* Common code for execute, invoke and submit
549		*/
550		private <T> void doSubmit(ForkJoinTask<T> task) {
551	+	if (task == null)
552	+	throw new NullPointerException();
553		if (isShutdown())
554		throw new RejectedExecutionException();
555		if (workers == null)
#	Line 536 | Line 559 | public class ForkJoinPool extends Abstra
559		}
560
561		/**
562	<	* Performs the given task; returning its result upon completion
562	>	* Performs the given task, returning its result upon completion.
563	>	*
564		* @param task the task
565		* @return the task's result
566		* @throws NullPointerException if task is null
#	Line 549 | Line 573 | public class ForkJoinPool extends Abstra
573
574		/**
575		* Arranges for (asynchronous) execution of the given task.
576	+	*
577		* @param task the task
578		* @throws NullPointerException if task is null
579		* @throws RejectedExecutionException if pool is shut down
#	Line 560 | Line 585 | public class ForkJoinPool extends Abstra
585		// AbstractExecutorService methods
586
587		public void execute(Runnable task) {
588	<	doSubmit(new AdaptedRunnable<Void>(task, null));
588	>	ForkJoinTask<?> job;
589	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
590	>	job = (ForkJoinTask<?>) task;
591	>	else
592	>	job = new AdaptedRunnable<Void>(task, null);
593	>	doSubmit(job);
594		}
595
596		public <T> ForkJoinTask<T> submit(Callable<T> task) {
#	Line 576 | Line 606 | public class ForkJoinPool extends Abstra
606		}
607
608		public ForkJoinTask<?> submit(Runnable task) {
609	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
609	>	ForkJoinTask<?> job;
610	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
611	>	job = (ForkJoinTask<?>) task;
612	>	else
613	>	job = new AdaptedRunnable<Void>(task, null);
614		doSubmit(job);
615		return job;
616		}
617
618		/**
619	+	* Submits a ForkJoinTask for execution.
620	+	*
621	+	* @param task the task to submit
622	+	* @return the task
623	+	* @throws RejectedExecutionException if the task cannot be
624	+	*         scheduled for execution
625	+	* @throws NullPointerException if the task is null
626	+	*/
627	+	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
628	+	doSubmit(task);
629	+	return task;
630	+	}
631	+
632	+	/**
633		* Adaptor for Runnables. This implements RunnableFuture
634	<	* to be compliant with AbstractExecutorService constraints
634	>	* to be compliant with AbstractExecutorService constraints.
635		*/
636		static final class AdaptedRunnable<T> extends ForkJoinTask<T>
637		implements RunnableFuture<T> {
#	Line 603 | Line 651 | public class ForkJoinPool extends Abstra
651		return true;
652		}
653		public void run() { invoke(); }
654	+	private static final long serialVersionUID = 5232453952276885070L;
655		}
656
657		/**
#	Line 631 | Line 680 | public class ForkJoinPool extends Abstra
680		}
681		}
682		public void run() { invoke(); }
683	+	private static final long serialVersionUID = 2838392045355241008L;
684		}
685
686		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
687	<	ArrayList<ForkJoinTask<T>> ts =
687	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
688		new ArrayList<ForkJoinTask<T>>(tasks.size());
689	<	for (Callable<T> c : tasks)
690	<	ts.add(new AdaptedCallable<T>(c));
691	<	invoke(new InvokeAll<T>(ts));
692	<	return (List<Future<T>>)(List)ts;
689	>	for (Callable<T> task : tasks)
690	>	forkJoinTasks.add(new AdaptedCallable<T>(task));
691	>	invoke(new InvokeAll<T>(forkJoinTasks));
692	>
693	>	@SuppressWarnings({"unchecked", "rawtypes"})
694	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
695	>	return futures;
696		}
697
698		static final class InvokeAll<T> extends RecursiveAction {
699		final ArrayList<ForkJoinTask<T>> tasks;
700		InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
701		public void compute() {
702	<	try { invokeAll(tasks); } catch(Exception ignore) {}
702	>	try { invokeAll(tasks); }
703	>	catch (Exception ignore) {}
704		}
705	+	private static final long serialVersionUID = -7914297376763021607L;
706		}
707
708		// Configuration and status settings and queries
709
710		/**
711	<	* Returns the factory used for constructing new workers
711	>	* Returns the factory used for constructing new workers.
712		*
713		* @return the factory used for constructing new workers
714		*/
#	Line 664 | Line 719 | public class ForkJoinPool extends Abstra
719		/**
720		* Returns the handler for internal worker threads that terminate
721		* due to unrecoverable errors encountered while executing tasks.
722	<	* @return the handler, or null if none
722	>	*
723	>	* @return the handler, or {@code null} if none
724		*/
725		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
726		Thread.UncaughtExceptionHandler h;
#	Line 685 | Line 741 | public class ForkJoinPool extends Abstra
741		* as handler.
742		*
743		* @param h the new handler
744	<	* @return the old handler, or null if none
744	>	* @return the old handler, or {@code null} if none
745		* @throws SecurityException if a security manager exists and
746		*         the caller is not permitted to modify threads
747		*         because it does not hold {@link
748	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
748	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
749		*/
750		public Thread.UncaughtExceptionHandler
751		setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
#	Line 716 | Line 772 | public class ForkJoinPool extends Abstra
772
773
774		/**
775	<	* Sets the target paralleism level of this pool.
775	>	* Sets the target parallelism level of this pool.
776	>	*
777		* @param parallelism the target parallelism
778		* @throws IllegalArgumentException if parallelism less than or
779	<	* equal to zero or greater than maximum size bounds.
779	>	* equal to zero or greater than maximum size bounds
780		* @throws SecurityException if a security manager exists and
781		*         the caller is not permitted to modify threads
782		*         because it does not hold {@link
783	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
783	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
784		*/
785		public void setParallelism(int parallelism) {
786		checkPermission();
#	Line 758 | Line 815 | public class ForkJoinPool extends Abstra
815		/**
816		* Returns the number of worker threads that have started but not
817		* yet terminated.  This result returned by this method may differ
818	<	* from <code>getParallelism</code> when threads are created to
818	>	* from {@link #getParallelism} when threads are created to
819		* maintain parallelism when others are cooperatively blocked.
820		*
821		* @return the number of worker threads
#	Line 770 | Line 827 | public class ForkJoinPool extends Abstra
827		/**
828		* Returns the maximum number of threads allowed to exist in the
829		* pool, even if there are insufficient unblocked running threads.
830	+	*
831		* @return the maximum
832		*/
833		public int getMaximumPoolSize() {
#	Line 781 | Line 839 | public class ForkJoinPool extends Abstra
839		* pool, even if there are insufficient unblocked running threads.
840		* Setting this value has no effect on current pool size. It
841		* controls construction of new threads.
842	+	*
843		* @throws IllegalArgumentException if negative or greater then
844	<	* internal implementation limit.
844	>	* internal implementation limit
845		*/
846		public void setMaximumPoolSize(int newMax) {
847		if (newMax < 0 || newMax > MAX_THREADS)
#	Line 792 | Line 851 | public class ForkJoinPool extends Abstra
851
852
853		/**
854	<	* Returns true if this pool dynamically maintains its target
855	<	* parallelism level. If false, new threads are added only to
856	<	* avoid possible starvation.
857	<	* This setting is by default true;
858	<	* @return true if maintains parallelism
854	>	* Returns {@code true} if this pool dynamically maintains its
855	>	* target parallelism level. If false, new threads are added only
856	>	* to avoid possible starvation.  This setting is by default true.
857	>	*
858	>	* @return {@code true} if maintains parallelism
859		*/
860		public boolean getMaintainsParallelism() {
861		return maintainsParallelism;
#	Line 806 | Line 865 | public class ForkJoinPool extends Abstra
865		* Sets whether this pool dynamically maintains its target
866		* parallelism level. If false, new threads are added only to
867		* avoid possible starvation.
868	<	* @param enable true to maintains parallelism
868	>	*
869	>	* @param enable {@code true} to maintain parallelism
870		*/
871		public void setMaintainsParallelism(boolean enable) {
872		maintainsParallelism = enable;
#	Line 817 | Line 877 | public class ForkJoinPool extends Abstra
877		* tasks that are never joined. This mode may be more appropriate
878		* than default locally stack-based mode in applications in which
879		* worker threads only process asynchronous tasks.  This method is
880	<	* designed to be invoked only when pool is quiescent, and
880	>	* designed to be invoked only when the pool is quiescent, and
881		* typically only before any tasks are submitted. The effects of
882	<	* invocations at ather times may be unpredictable.
882	>	* invocations at other times may be unpredictable.
883		*
884	<	* @param async if true, use locally FIFO scheduling
885	<	* @return the previous mode.
884	>	* @param async if {@code true}, use locally FIFO scheduling
885	>	* @return the previous mode
886	>	* @see #getAsyncMode
887		*/
888		public boolean setAsyncMode(boolean async) {
889		boolean oldMode = locallyFifo;
#	Line 839 | Line 900 | public class ForkJoinPool extends Abstra
900		}
901
902		/**
903	<	* Returns true if this pool uses local first-in-first-out
903	>	* Returns {@code true} if this pool uses local first-in-first-out
904		* scheduling mode for forked tasks that are never joined.
905		*
906	<	* @return true if this pool uses async mode.
906	>	* @return {@code true} if this pool uses async mode
907	>	* @see #setAsyncMode
908		*/
909		public boolean getAsyncMode() {
910		return locallyFifo;
#	Line 863 | Line 925 | public class ForkJoinPool extends Abstra
925		* Returns an estimate of the number of threads that are currently
926		* stealing or executing tasks. This method may overestimate the
927		* number of active threads.
928	<	* @return the number of active threads.
928	>	*
929	>	* @return the number of active threads
930		*/
931		public int getActiveThreadCount() {
932		return activeCountOf(runControl);
#	Line 873 | Line 936 | public class ForkJoinPool extends Abstra
936		* Returns an estimate of the number of threads that are currently
937		* idle waiting for tasks. This method may underestimate the
938		* number of idle threads.
939	<	* @return the number of idle threads.
939	>	*
940	>	* @return the number of idle threads
941		*/
942		final int getIdleThreadCount() {
943		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
944	<	return (c <= 0)? 0 : c;
944	>	return (c <= 0) ? 0 : c;
945		}
946
947		/**
948	<	* Returns true if all worker threads are currently idle. An idle
949	<	* worker is one that cannot obtain a task to execute because none
950	<	* are available to steal from other threads, and there are no
951	<	* pending submissions to the pool. This method is conservative:
952	<	* It might not return true immediately upon idleness of all
953	<	* threads, but will eventually become true if threads remain
954	<	* inactive.
955	<	* @return true if all threads are currently idle
948	>	* Returns {@code true} if all worker threads are currently idle.
949	>	* An idle worker is one that cannot obtain a task to execute
950	>	* because none are available to steal from other threads, and
951	>	* there are no pending submissions to the pool. This method is
952	>	* conservative; it might not return {@code true} immediately upon
953	>	* idleness of all threads, but will eventually become true if
954	>	* threads remain inactive.
955	>	*
956	>	* @return {@code true} if all threads are currently idle
957		*/
958		public boolean isQuiescent() {
959		return activeCountOf(runControl) == 0;
#	Line 899 | Line 964 | public class ForkJoinPool extends Abstra
964		* one thread's work queue by another. The reported value
965		* underestimates the actual total number of steals when the pool
966		* is not quiescent. This value may be useful for monitoring and
967	<	* tuning fork/join programs: In general, steal counts should be
967	>	* tuning fork/join programs: in general, steal counts should be
968		* high enough to keep threads busy, but low enough to avoid
969		* overhead and contention across threads.
970	<	* @return the number of steals.
970	>	*
971	>	* @return the number of steals
972		*/
973		public long getStealCount() {
974		return stealCount.get();
975		}
976
977		/**
978	<	* Accumulate steal count from a worker. Call only
979	<	* when worker known to be idle.
978	>	* Accumulates steal count from a worker.
979	>	* Call only when worker known to be idle.
980		*/
981		private void updateStealCount(ForkJoinWorkerThread w) {
982		int sc = w.getAndClearStealCount();
#	Line 925 | Line 991 | public class ForkJoinPool extends Abstra
991		* an approximation, obtained by iterating across all threads in
992		* the pool. This method may be useful for tuning task
993		* granularities.
994	<	* @return the number of queued tasks.
994	>	*
995	>	* @return the number of queued tasks
996		*/
997		public long getQueuedTaskCount() {
998		long count = 0;
#	Line 944 | Line 1011 | public class ForkJoinPool extends Abstra
1011		* Returns an estimate of the number tasks submitted to this pool
1012		* that have not yet begun executing. This method takes time
1013		* proportional to the number of submissions.
1014	<	* @return the number of queued submissions.
1014	>	*
1015	>	* @return the number of queued submissions
1016		*/
1017		public int getQueuedSubmissionCount() {
1018		return submissionQueue.size();
1019		}
1020
1021		/**
1022	<	* Returns true if there are any tasks submitted to this pool
1023	<	* that have not yet begun executing.
1024	<	* @return <code>true</code> if there are any queued submissions.
1022	>	* Returns {@code true} if there are any tasks submitted to this
1023	>	* pool that have not yet begun executing.
1024	>	*
1025	>	* @return {@code true} if there are any queued submissions
1026		*/
1027		public boolean hasQueuedSubmissions() {
1028		return !submissionQueue.isEmpty();
#	Line 963 | Line 1032 | public class ForkJoinPool extends Abstra
1032		* Removes and returns the next unexecuted submission if one is
1033		* available.  This method may be useful in extensions to this
1034		* class that re-assign work in systems with multiple pools.
1035	<	* @return the next submission, or null if none
1035	>	*
1036	>	* @return the next submission, or {@code null} if none
1037		*/
1038		protected ForkJoinTask<?> pollSubmission() {
1039		return submissionQueue.poll();
#	Line 973 | Line 1043 | public class ForkJoinPool extends Abstra
1043		* Removes all available unexecuted submitted and forked tasks
1044		* from scheduling queues and adds them to the given collection,
1045		* without altering their execution status. These may include
1046	<	* artifically generated or wrapped tasks. This method id designed
1046	>	* artificially generated or wrapped tasks. This method is designed
1047		* to be invoked only when the pool is known to be
1048		* quiescent. Invocations at other times may not remove all
1049		* tasks. A failure encountered while attempting to add elements
1050	<	* to collection <tt>c</tt> may result in elements being in
1050	>	* to collection {@code c} may result in elements being in
1051		* neither, either or both collections when the associated
1052		* exception is thrown.  The behavior of this operation is
1053		* undefined if the specified collection is modified while the
1054		* operation is in progress.
1055	+	*
1056		* @param c the collection to transfer elements into
1057		* @return the number of elements transferred
1058		*/
1059	<	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
1059	>	protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {
1060		int n = submissionQueue.drainTo(c);
1061		ForkJoinWorkerThread[] ws = workers;
1062		if (ws != null) {
#	Line 1042 | Line 1113 | public class ForkJoinPool extends Abstra
1113		* Invocation has no additional effect if already shut down.
1114		* Tasks that are in the process of being submitted concurrently
1115		* during the course of this method may or may not be rejected.
1116	+	*
1117		* @throws SecurityException if a security manager exists and
1118		*         the caller is not permitted to modify threads
1119		*         because it does not hold {@link
1120	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1120	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1121		*/
1122		public void shutdown() {
1123		checkPermission();
1124		transitionRunStateTo(SHUTDOWN);
1125	<	if (canTerminateOnShutdown(runControl))
1125	>	if (canTerminateOnShutdown(runControl)) {
1126	>	if (workers == null) { // shutting down before workers created
1127	>	final ReentrantLock lock = this.workerLock;
1128	>	lock.lock();
1129	>	try {
1130	>	if (workers == null) {
1131	>	terminate();
1132	>	transitionRunStateTo(TERMINATED);
1133	>	termination.signalAll();
1134	>	}
1135	>	} finally {
1136	>	lock.unlock();
1137	>	}
1138	>	}
1139		terminateOnShutdown();
1140	+	}
1141		}
1142
1143		/**
#	Line 1061 | Line 1147 | public class ForkJoinPool extends Abstra
1147		* method may or may not be rejected. Unlike some other executors,
1148		* this method cancels rather than collects non-executed tasks
1149		* upon termination, so always returns an empty list. However, you
1150	<	* can use method <code>drainTasksTo</code> before invoking this
1150	>	* can use method {@link #drainTasksTo} before invoking this
1151		* method to transfer unexecuted tasks to another collection.
1152	+	*
1153		* @return an empty list
1154		* @throws SecurityException if a security manager exists and
1155		*         the caller is not permitted to modify threads
1156		*         because it does not hold {@link
1157	<	*         java.lang.RuntimePermission}<code>("modifyThread")</code>,
1157	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1158		*/
1159		public List<Runnable> shutdownNow() {
1160		checkPermission();
#	Line 1076 | Line 1163 | public class ForkJoinPool extends Abstra
1163		}
1164
1165		/**
1166	<	* Returns <code>true</code> if all tasks have completed following shut down.
1166	>	* Returns {@code true} if all tasks have completed following shut down.
1167		*
1168	<	* @return <code>true</code> if all tasks have completed following shut down
1168	>	* @return {@code true} if all tasks have completed following shut down
1169		*/
1170		public boolean isTerminated() {
1171		return runStateOf(runControl) == TERMINATED;
1172		}
1173
1174		/**
1175	<	* Returns <code>true</code> if the process of termination has
1175	>	* Returns {@code true} if the process of termination has
1176		* commenced but possibly not yet completed.
1177		*
1178	<	* @return <code>true</code> if terminating
1178	>	* @return {@code true} if terminating
1179		*/
1180		public boolean isTerminating() {
1181		return runStateOf(runControl) >= TERMINATING;
1182		}
1183
1184		/**
1185	<	* Returns <code>true</code> if this pool has been shut down.
1185	>	* Returns {@code true} if this pool has been shut down.
1186		*
1187	<	* @return <code>true</code> if this pool has been shut down
1187	>	* @return {@code true} if this pool has been shut down
1188		*/
1189		public boolean isShutdown() {
1190		return runStateOf(runControl) >= SHUTDOWN;
#	Line 1110 | Line 1197 | public class ForkJoinPool extends Abstra
1197		*
1198		* @param timeout the maximum time to wait
1199		* @param unit the time unit of the timeout argument
1200	<	* @return <code>true</code> if this executor terminated and
1201	<	*         <code>false</code> if the timeout elapsed before termination
1200	>	* @return {@code true} if this executor terminated and
1201	>	*         {@code false} if the timeout elapsed before termination
1202		* @throws InterruptedException if interrupted while waiting
1203		*/
1204		public boolean awaitTermination(long timeout, TimeUnit unit)
#	Line 1135 | Line 1222 | public class ForkJoinPool extends Abstra
1222		// Shutdown and termination support
1223
1224		/**
1225	<	* Callback from terminating worker. Null out the corresponding
1226	<	* workers slot, and if terminating, try to terminate, else try to
1227	<	* shrink workers array.
1225	>	* Callback from terminating worker. Nulls out the corresponding
1226	>	* workers slot, and if terminating, tries to terminate; else
1227	>	* tries to shrink workers array.
1228	>	*
1229		* @param w the worker
1230		*/
1231		final void workerTerminated(ForkJoinWorkerThread w) {
#	Line 1168 | Line 1256 | public class ForkJoinPool extends Abstra
1256		}
1257
1258		/**
1259	<	* Initiate termination.
1259	>	* Initiates termination.
1260		*/
1261		private void terminate() {
1262		if (transitionRunStateTo(TERMINATING)) {
#	Line 1183 | Line 1271 | public class ForkJoinPool extends Abstra
1271		}
1272
1273		/**
1274	<	* Possibly terminate when on shutdown state
1274	>	* Possibly terminates when on shutdown state.
1275		*/
1276		private void terminateOnShutdown() {
1277		if (!hasQueuedSubmissions() && canTerminateOnShutdown(runControl))
#	Line 1191 | Line 1279 | public class ForkJoinPool extends Abstra
1279		}
1280
1281		/**
1282	<	* Clear out and cancel submissions
1282	>	* Clears out and cancels submissions.
1283		*/
1284		private void cancelQueuedSubmissions() {
1285		ForkJoinTask<?> task;
#	Line 1200 | Line 1288 | public class ForkJoinPool extends Abstra
1288		}
1289
1290		/**
1291	<	* Clean out worker queues.
1291	>	* Cleans out worker queues.
1292		*/
1293		private void cancelQueuedWorkerTasks() {
1294		final ReentrantLock lock = this.workerLock;
#	Line 1220 | Line 1308 | public class ForkJoinPool extends Abstra
1308		}
1309
1310		/**
1311	<	* Set each worker's status to terminating. Requires lock to avoid
1312	<	* conflicts with add/remove
1311	>	* Sets each worker's status to terminating. Requires lock to avoid
1312	>	* conflicts with add/remove.
1313		*/
1314		private void stopAllWorkers() {
1315		final ReentrantLock lock = this.workerLock;
#	Line 1241 | Line 1329 | public class ForkJoinPool extends Abstra
1329		}
1330
1331		/**
1332	<	* Interrupt all unterminated workers.  This is not required for
1332	>	* Interrupts all unterminated workers.  This is not required for
1333		* sake of internal control, but may help unstick user code during
1334		* shutdown.
1335		*/
#	Line 1311 | Line 1399 | public class ForkJoinPool extends Abstra
1399		}
1400
1401		/**
1402	<	* Wake up waiter, returning false if known to already
1402	>	* Wakes up waiter, returning false if known to already
1403		*/
1404		boolean signal() {
1405		ForkJoinWorkerThread t = thread;
#	Line 1323 | Line 1411 | public class ForkJoinPool extends Abstra
1411		}
1412
1413		/**
1414	<	* Await release on sync
1414	>	* Awaits release on sync.
1415		*/
1416		void awaitSyncRelease(ForkJoinPool p) {
1417		while (thread != null && !p.syncIsReleasable(this))
#	Line 1331 | Line 1419 | public class ForkJoinPool extends Abstra
1419		}
1420
1421		/**
1422	<	* Await resumption as spare
1422	>	* Awaits resumption as spare.
1423		*/
1424		void awaitSpareRelease() {
1425		while (thread != null) {
#	Line 1345 | Line 1433 | public class ForkJoinPool extends Abstra
1433		* Ensures that no thread is waiting for count to advance from the
1434		* current value of eventCount read on entry to this method, by
1435		* releasing waiting threads if necessary.
1436	+	*
1437		* @return the count
1438		*/
1439		final long ensureSync() {
#	Line 1366 | Line 1455 | public class ForkJoinPool extends Abstra
1455		*/
1456		private void signalIdleWorkers() {
1457		long c;
1458	<	do;while (!casEventCount(c = eventCount, c+1));
1458	>	do {} while (!casEventCount(c = eventCount, c+1));
1459		ensureSync();
1460		}
1461
1462		/**
1463	<	* Signal threads waiting to poll a task. Because method sync
1463	>	* Signals threads waiting to poll a task. Because method sync
1464		* rechecks availability, it is OK to only proceed if queue
1465		* appears to be non-empty, and OK to skip under contention to
1466		* increment count (since some other thread succeeded).
#	Line 1390 | Line 1479 | public class ForkJoinPool extends Abstra
1479		* Waits until event count advances from last value held by
1480		* caller, or if excess threads, caller is resumed as spare, or
1481		* caller or pool is terminating. Updates caller's event on exit.
1482	+	*
1483		* @param w the calling worker thread
1484		*/
1485		final void sync(ForkJoinWorkerThread w) {
#	Line 1417 | Line 1507 | public class ForkJoinPool extends Abstra
1507		}
1508
1509		/**
1510	<	* Returns true if worker waiting on sync can proceed:
1510	>	* Returns {@code true} if worker waiting on sync can proceed:
1511		*  - on signal (thread == null)
1512		*  - on event count advance (winning race to notify vs signaller)
1513	<	*  - on Interrupt
1513	>	*  - on interrupt
1514		*  - if the first queued node, we find work available
1515		* If node was not signalled and event count not advanced on exit,
1516		* then we also help advance event count.
1517	<	* @return true if node can be released
1517	>	*
1518	>	* @return {@code true} if node can be released
1519		*/
1520		final boolean syncIsReleasable(WaitQueueNode node) {
1521		long prev = node.count;
#	Line 1443 | Line 1534 | public class ForkJoinPool extends Abstra
1534		}
1535
1536		/**
1537	<	* Returns true if a new sync event occurred since last call to
1538	<	* sync or this method, if so, updating caller's count.
1537	>	* Returns {@code true} if a new sync event occurred since last
1538	>	* call to sync or this method, if so, updating caller's count.
1539		*/
1540		final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1541		long lc = w.lastEventCount;
#	Line 1458 | Line 1549 | public class ForkJoinPool extends Abstra
1549		//  Parallelism maintenance
1550
1551		/**
1552	<	* Decrement running count; if too low, add spare.
1552	>	* Decrements running count; if too low, adds spare.
1553		*
1554		* Conceptually, all we need to do here is add or resume a
1555		* spare thread when one is about to block (and remove or
1556		* suspend it later when unblocked -- see suspendIfSpare).
1557		* However, implementing this idea requires coping with
1558	<	* several problems: We have imperfect information about the
1558	>	* several problems: we have imperfect information about the
1559		* states of threads. Some count updates can and usually do
1560		* lag run state changes, despite arrangements to keep them
1561		* accurate (for example, when possible, updating counts
#	Line 1478 | Line 1569 | public class ForkJoinPool extends Abstra
1569		* only be suspended or removed when they are idle, not
1570		* immediately when they aren't needed. So adding threads will
1571		* raise parallelism level for longer than necessary.  Also,
1572	<	* FJ applications often enounter highly transient peaks when
1572	>	* FJ applications often encounter highly transient peaks when
1573		* many threads are blocked joining, but for less time than it
1574		* takes to create or resume spares.
1575		*
#	Line 1487 | Line 1578 | public class ForkJoinPool extends Abstra
1578		* target counts, else create only to avoid starvation
1579		* @return true if joinMe known to be done
1580		*/
1581	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1581	>	final boolean preJoin(ForkJoinTask<?> joinMe,
1582	>	boolean maintainParallelism) {
1583		maintainParallelism &= maintainsParallelism; // overrride
1584		boolean dec = false;  // true when running count decremented
1585		while (spareStack == null || !tryResumeSpare(dec)) {
1586		int counts = workerCounts;
1587	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1587	>	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1588	>	// CAS cheat
1589		if (!needSpare(counts, maintainParallelism))
1590		break;
1591		if (joinMe.status < 0)
#	Line 1507 | Line 1600 | public class ForkJoinPool extends Abstra
1600		/**
1601		* Same idea as preJoin
1602		*/
1603	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1603	>	final boolean preBlock(ManagedBlocker blocker,
1604	>	boolean maintainParallelism) {
1605		maintainParallelism &= maintainsParallelism;
1606		boolean dec = false;
1607		while (spareStack == null || !tryResumeSpare(dec)) {
#	Line 1525 | Line 1619 | public class ForkJoinPool extends Abstra
1619		}
1620
1621		/**
1622	<	* Returns true if a spare thread appears to be needed.  If
1623	<	* maintaining parallelism, returns true when the deficit in
1622	>	* Returns {@code true} if a spare thread appears to be needed.
1623	>	* If maintaining parallelism, returns true when the deficit in
1624		* running threads is more than the surplus of total threads, and
1625		* there is apparently some work to do.  This self-limiting rule
1626		* means that the more threads that have already been added, the
1627		* less parallelism we will tolerate before adding another.
1628	+	*
1629		* @param counts current worker counts
1630		* @param maintainParallelism try to maintain parallelism
1631		*/
#	Line 1548 | Line 1643 | public class ForkJoinPool extends Abstra
1643		}
1644
1645		/**
1646	<	* Add a spare worker if lock available and no more than the
1647	<	* expected numbers of threads exist
1646	>	* Adds a spare worker if lock available and no more than the
1647	>	* expected numbers of threads exist.
1648	>	*
1649		* @return true if successful
1650		*/
1651		private boolean tryAddSpare(int expectedCounts) {
#	Line 1582 | Line 1678 | public class ForkJoinPool extends Abstra
1678		}
1679
1680		/**
1681	<	* Add the kth spare worker. On entry, pool coounts are already
1681	>	* Adds the kth spare worker. On entry, pool counts are already
1682		* adjusted to reflect addition.
1683		*/
1684		private void createAndStartSpare(int k) {
#	Line 1604 | Line 1700 | public class ForkJoinPool extends Abstra
1700		}
1701
1702		/**
1703	<	* Suspend calling thread w if there are excess threads.  Called
1704	<	* only from sync.  Spares are enqueued in a Treiber stack
1705	<	* using the same WaitQueueNodes as barriers.  They are resumed
1706	<	* mainly in preJoin, but are also woken on pool events that
1707	<	* require all threads to check run state.
1703	>	* Suspends calling thread w if there are excess threads.  Called
1704	>	* only from sync.  Spares are enqueued in a Treiber stack using
1705	>	* the same WaitQueueNodes as barriers.  They are resumed mainly
1706	>	* in preJoin, but are also woken on pool events that require all
1707	>	* threads to check run state.
1708	>	*
1709		* @param w the caller
1710		*/
1711		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1619 | Line 1716 | public class ForkJoinPool extends Abstra
1716		node = new WaitQueueNode(0, w);
1717		if (casWorkerCounts(s, s-1)) { // representation-dependent
1718		// push onto stack
1719	<	do;while (!casSpareStack(node.next = spareStack, node));
1719	>	do {} while (!casSpareStack(node.next = spareStack, node));
1720		// block until released by resumeSpare
1721		node.awaitSpareRelease();
1722		return true;
#	Line 1629 | Line 1726 | public class ForkJoinPool extends Abstra
1726		}
1727
1728		/**
1729	<	* Try to pop and resume a spare thread.
1729	>	* Tries to pop and resume a spare thread.
1730	>	*
1731		* @param updateCount if true, increment running count on success
1732		* @return true if successful
1733		*/
#	Line 1647 | Line 1745 | public class ForkJoinPool extends Abstra
1745		}
1746
1747		/**
1748	<	* Pop and resume all spare threads. Same idea as ensureSync.
1748	>	* Pops and resumes all spare threads. Same idea as ensureSync.
1749	>	*
1750		* @return true if any spares released
1751		*/
1752		private boolean resumeAllSpares() {
#	Line 1665 | Line 1764 | public class ForkJoinPool extends Abstra
1764		}
1765
1766		/**
1767	<	* Pop and shutdown excessive spare threads. Call only while
1767	>	* Pops and shuts down excessive spare threads. Call only while
1768		* holding lock. This is not guaranteed to eliminate all excess
1769		* threads, only those suspended as spares, which are the ones
1770		* unlikely to be needed in the future.
#	Line 1690 | Line 1789 | public class ForkJoinPool extends Abstra
1789		/**
1790		* Interface for extending managed parallelism for tasks running
1791		* in ForkJoinPools. A ManagedBlocker provides two methods.
1792	<	* Method <code>isReleasable</code> must return true if blocking is not
1793	<	* necessary. Method <code>block</code> blocks the current thread
1794	<	* if necessary (perhaps internally invoking isReleasable before
1795	<	* actually blocking.).
1792	>	* Method {@code isReleasable} must return {@code true} if
1793	>	* blocking is not necessary. Method {@code block} blocks the
1794	>	* current thread if necessary (perhaps internally invoking
1795	>	* {@code isReleasable} before actually blocking.).
1796	>	*
1797		* <p>For example, here is a ManagedBlocker based on a
1798		* ReentrantLock:
1799	<	* <pre>
1800	<	*   class ManagedLocker implements ManagedBlocker {
1801	<	*     final ReentrantLock lock;
1802	<	*     boolean hasLock = false;
1803	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1804	<	*     public boolean block() {
1805	<	*        if (!hasLock)
1806	<	*           lock.lock();
1807	<	*        return true;
1808	<	*     }
1809	<	*     public boolean isReleasable() {
1810	<	*        return hasLock || (hasLock = lock.tryLock());
1711	<	*     }
1799	>	*  <pre> {@code
1800	>	* class ManagedLocker implements ManagedBlocker {
1801	>	*   final ReentrantLock lock;
1802	>	*   boolean hasLock = false;
1803	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1804	>	*   public boolean block() {
1805	>	*     if (!hasLock)
1806	>	*       lock.lock();
1807	>	*     return true;
1808	>	*   }
1809	>	*   public boolean isReleasable() {
1810	>	*     return hasLock || (hasLock = lock.tryLock());
1811		*   }
1812	<	* </pre>
1812	>	* }}</pre>
1813		*/
1814		public static interface ManagedBlocker {
1815		/**
1816		* Possibly blocks the current thread, for example waiting for
1817		* a lock or condition.
1818	<	* @return true if no additional blocking is necessary (i.e.,
1819	<	* if isReleasable would return true).
1818	>	*
1819	>	* @return {@code true} if no additional blocking is necessary
1820	>	* (i.e., if isReleasable would return true)
1821		* @throws InterruptedException if interrupted while waiting
1822	<	* (the method is not required to do so, but is allowe to).
1822	>	* (the method is not required to do so, but is allowed to)
1823		*/
1824		boolean block() throws InterruptedException;
1825
1826		/**
1827	<	* Returns true if blocking is unnecessary.
1827	>	* Returns {@code true} if blocking is unnecessary.
1828		*/
1829		boolean isReleasable();
1830		}
#	Line 1734 | Line 1834 | public class ForkJoinPool extends Abstra
1834		* is a ForkJoinWorkerThread, this method possibly arranges for a
1835		* spare thread to be activated if necessary to ensure parallelism
1836		* while the current thread is blocked.  If
1837	<	* <code>maintainParallelism</code> is true and the pool supports
1837	>	* {@code maintainParallelism} is {@code true} and the pool supports
1838		* it ({@link #getMaintainsParallelism}), this method attempts to
1839	<	* maintain the pool's nominal parallelism. Otherwise if activates
1839	>	* maintain the pool's nominal parallelism. Otherwise it activates
1840		* a thread only if necessary to avoid complete starvation. This
1841		* option may be preferable when blockages use timeouts, or are
1842		* almost always brief.
1843		*
1844		* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1845		* equivalent to
1846	<	* <pre>
1847	<	*   while (!blocker.isReleasable())
1848	<	*      if (blocker.block())
1849	<	*         return;
1850	<	* </pre>
1846	>	*  <pre> {@code
1847	>	* while (!blocker.isReleasable())
1848	>	*   if (blocker.block())
1849	>	*     return;
1850	>	* }</pre>
1851		* If the caller is a ForkJoinTask, then the pool may first
1852		* be expanded to ensure parallelism, and later adjusted.
1853		*
1854		* @param blocker the blocker
1855	<	* @param maintainParallelism if true and supported by this pool,
1856	<	* attempt to maintain the pool's nominal parallelism; otherwise
1857	<	* activate a thread only if necessary to avoid complete
1858	<	* starvation.
1859	<	* @throws InterruptedException if blocker.block did so.
1855	>	* @param maintainParallelism if {@code true} and supported by
1856	>	* this pool, attempt to maintain the pool's nominal parallelism;
1857	>	* otherwise activate a thread only if necessary to avoid
1858	>	* complete starvation.
1859	>	* @throws InterruptedException if blocker.block did so
1860		*/
1861		public static void managedBlock(ManagedBlocker blocker,
1862		boolean maintainParallelism)
1863		throws InterruptedException {
1864		Thread t = Thread.currentThread();
1865	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
1866	<	((ForkJoinWorkerThread)t).pool : null);
1865	>	ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
1866	>	((ForkJoinWorkerThread) t).pool : null);
1867		if (!blocker.isReleasable()) {
1868		try {
1869		if (pool == null ||
#	Line 1778 | Line 1878 | public class ForkJoinPool extends Abstra
1878
1879		private static void awaitBlocker(ManagedBlocker blocker)
1880		throws InterruptedException {
1881	<	do;while (!blocker.isReleasable() && !blocker.block());
1881	>	do {} while (!blocker.isReleasable() && !blocker.block());
1882		}
1883
1884		// AbstractExecutorService overrides
1885
1886		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1887	<	return new AdaptedRunnable(runnable, value);
1887	>	return new AdaptedRunnable<T>(runnable, value);
1888		}
1889
1890		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1891	<	return new AdaptedCallable(callable);
1792	<	}
1793	<
1794	<
1795	<	// Temporary Unsafe mechanics for preliminary release
1796	<	private static Unsafe getUnsafe() throws Throwable {
1797	<	try {
1798	<	return Unsafe.getUnsafe();
1799	<	} catch (SecurityException se) {
1800	<	try {
1801	<	return java.security.AccessController.doPrivileged
1802	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1803	<	public Unsafe run() throws Exception {
1804	<	return getUnsafePrivileged();
1805	<	}});
1806	<	} catch (java.security.PrivilegedActionException e) {
1807	<	throw e.getCause();
1808	<	}
1809	<	}
1891	>	return new AdaptedCallable<T>(callable);
1892		}
1893
1894	<	private static Unsafe getUnsafePrivileged()
1813	<	throws NoSuchFieldException, IllegalAccessException {
1814	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1815	<	f.setAccessible(true);
1816	<	return (Unsafe) f.get(null);
1817	<	}
1818	<
1819	<	private static long fieldOffset(String fieldName)
1820	<	throws NoSuchFieldException {
1821	<	return _unsafe.objectFieldOffset
1822	<	(ForkJoinPool.class.getDeclaredField(fieldName));
1823	<	}
1894	>	// Unsafe mechanics
1895
1896	<	static final Unsafe _unsafe;
1897	<	static final long eventCountOffset;
1898	<	static final long workerCountsOffset;
1899	<	static final long runControlOffset;
1900	<	static final long syncStackOffset;
1901	<	static final long spareStackOffset;
1902	<
1903	<	static {
1904	<	try {
1905	<	_unsafe = getUnsafe();
1906	<	eventCountOffset = fieldOffset("eventCount");
1836	<	workerCountsOffset = fieldOffset("workerCounts");
1837	<	runControlOffset = fieldOffset("runControl");
1838	<	syncStackOffset = fieldOffset("syncStack");
1839	<	spareStackOffset = fieldOffset("spareStack");
1840	<	} catch (Throwable e) {
1841	<	throw new RuntimeException("Could not initialize intrinsics", e);
1842	<	}
1843	<	}
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);
1909	>	return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1910		}
1911		private boolean casWorkerCounts(int cmp, int val) {
1912	<	return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1912	>	return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val);
1913		}
1914		private boolean casRunControl(int cmp, int val) {
1915	<	return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val);
1915	>	return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val);
1916		}
1917		private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) {
1918	<	return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val);
1918	>	return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val);
1919		}
1920		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1921	<	return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, 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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