ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

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

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.13 by jsr166, Wed Jul 22 01:36:51 2009 UTC vs.
Revision 1.22 by jsr166, Sat Jul 25 00:34:00 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
#	Line 90 | Line 97 | public class ForkJoinPool extends Abstra
97		}
98
99		/**
100	<	* Default ForkJoinWorkerThreadFactory implementation, creates a
100	>	* Default ForkJoinWorkerThreadFactory implementation; creates a
101		* new ForkJoinWorkerThread.
102		*/
103		static class  DefaultForkJoinWorkerThreadFactory
#	Line 184 | 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 219 | 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 232 | Line 239 | public class ForkJoinPool extends Abstra
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).
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		* 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 274 | 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.
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() {
#	Line 287 | Line 297 | public class ForkJoinPool extends Abstra
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 305 | Line 316 | public class ForkJoinPool extends Abstra
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 331 | 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")},
352	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
353		*/
354		public ForkJoinPool() {
355		this(Runtime.getRuntime().availableProcessors(),
#	Line 345 | Line 358 | public class ForkJoinPool extends Abstra
358
359		/**
360		* Creates a ForkJoinPool with the indicated parallelism level
361	<	* threads, and using the default ForkJoinWorkerThreadFactory,
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")},
369	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
370		*/
371		public ForkJoinPool(int parallelism) {
372		this(parallelism, defaultForkJoinWorkerThreadFactory);
#	Line 361 | 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")},
385	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
386		*/
387		public ForkJoinPool(ForkJoinWorkerThreadFactory factory) {
388		this(Runtime.getRuntime().availableProcessors(), factory);
#	Line 384 | Line 399 | public class ForkJoinPool extends Abstra
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")},
402	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
403		*/
404		public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) {
405		if (parallelism <= 0 || parallelism > MAX_THREADS)
#	Line 405 | 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 427 | Line 443 | public class ForkJoinPool extends Abstra
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		* Creates or resizes array if necessary to hold newLength.
453	<	* Call only under exclusion or lock.
453	>	* Call only under exclusion.
454	>	*
455		* @return the array
456		*/
457		private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) {
#	Line 447 | 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 463 | 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 539 | Line 557 | public class ForkJoinPool extends Abstra
557		}
558
559		/**
560	<	* Performs the given task; returning its result upon completion
560	>	* Performs the given task, returning its result upon completion.
561	>	*
562		* @param task the task
563		* @return the task's result
564		* @throws NullPointerException if task is null
#	Line 552 | Line 571 | public class ForkJoinPool extends Abstra
571
572		/**
573		* Arranges for (asynchronous) execution of the given task.
574	+	*
575		* @param task the task
576		* @throws NullPointerException if task is null
577		* @throws RejectedExecutionException if pool is shut down
#	Line 586 | Line 606 | public class ForkJoinPool extends Abstra
606
607		/**
608		* Adaptor for Runnables. This implements RunnableFuture
609	<	* to be compliant with AbstractExecutorService constraints
609	>	* to be compliant with AbstractExecutorService constraints.
610		*/
611		static final class AdaptedRunnable<T> extends ForkJoinTask<T>
612		implements RunnableFuture<T> {
#	Line 606 | Line 626 | public class ForkJoinPool extends Abstra
626		return true;
627		}
628		public void run() { invoke(); }
629	+	private static final long serialVersionUID = 5232453952276885070L;
630		}
631
632		/**
#	Line 634 | Line 655 | public class ForkJoinPool extends Abstra
655		}
656		}
657		public void run() { invoke(); }
658	+	private static final long serialVersionUID = 2838392045355241008L;
659		}
660
661		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
662	<	ArrayList<ForkJoinTask<T>> ts =
662	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
663		new ArrayList<ForkJoinTask<T>>(tasks.size());
664	<	for (Callable<T> c : tasks)
665	<	ts.add(new AdaptedCallable<T>(c));
666	<	invoke(new InvokeAll<T>(ts));
667	<	return (List<Future<T>>)(List)ts;
664	>	for (Callable<T> task : tasks)
665	>	forkJoinTasks.add(new AdaptedCallable<T>(task));
666	>	invoke(new InvokeAll<T>(forkJoinTasks));
667	>
668	>	@SuppressWarnings({"unchecked", "rawtypes"})
669	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
670	>	return futures;
671		}
672
673		static final class InvokeAll<T> extends RecursiveAction {
674		final ArrayList<ForkJoinTask<T>> tasks;
675		InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; }
676		public void compute() {
677	<	try { invokeAll(tasks); } catch(Exception ignore) {}
677	>	try { invokeAll(tasks); }
678	>	catch (Exception ignore) {}
679		}
680	+	private static final long serialVersionUID = -7914297376763021607L;
681		}
682
683		// Configuration and status settings and queries
684
685		/**
686	<	* Returns the factory used for constructing new workers
686	>	* Returns the factory used for constructing new workers.
687		*
688		* @return the factory used for constructing new workers
689		*/
#	Line 667 | Line 694 | public class ForkJoinPool extends Abstra
694		/**
695		* Returns the handler for internal worker threads that terminate
696		* due to unrecoverable errors encountered while executing tasks.
697	+	*
698		* @return the handler, or null if none
699		*/
700		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
#	Line 692 | Line 720 | public class ForkJoinPool extends Abstra
720		* @throws SecurityException if a security manager exists and
721		*         the caller is not permitted to modify threads
722		*         because it does not hold {@link
723	<	*         java.lang.RuntimePermission}{@code ("modifyThread")},
723	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
724		*/
725		public Thread.UncaughtExceptionHandler
726		setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) {
#	Line 720 | Line 748 | public class ForkJoinPool extends Abstra
748
749		/**
750		* Sets the target parallelism level of this pool.
751	+	*
752		* @param parallelism the target parallelism
753		* @throws IllegalArgumentException if parallelism less than or
754		* equal to zero or greater than maximum size bounds
755		* @throws SecurityException if a security manager exists and
756		*         the caller is not permitted to modify threads
757		*         because it does not hold {@link
758	<	*         java.lang.RuntimePermission}{@code ("modifyThread")},
758	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
759		*/
760		public void setParallelism(int parallelism) {
761		checkPermission();
#	Line 773 | Line 802 | public class ForkJoinPool extends Abstra
802		/**
803		* Returns the maximum number of threads allowed to exist in the
804		* pool, even if there are insufficient unblocked running threads.
805	+	*
806		* @return the maximum
807		*/
808		public int getMaximumPoolSize() {
#	Line 784 | Line 814 | public class ForkJoinPool extends Abstra
814		* pool, even if there are insufficient unblocked running threads.
815		* Setting this value has no effect on current pool size. It
816		* controls construction of new threads.
817	+	*
818		* @throws IllegalArgumentException if negative or greater then
819		* internal implementation limit
820		*/
#	Line 798 | Line 829 | public class ForkJoinPool extends Abstra
829		* Returns true if this pool dynamically maintains its target
830		* parallelism level. If false, new threads are added only to
831		* avoid possible starvation.
832	<	* This setting is by default true;
832	>	* This setting is by default true.
833	>	*
834		* @return true if maintains parallelism
835		*/
836		public boolean getMaintainsParallelism() {
#	Line 809 | Line 841 | public class ForkJoinPool extends Abstra
841		* Sets whether this pool dynamically maintains its target
842		* parallelism level. If false, new threads are added only to
843		* avoid possible starvation.
844	+	*
845		* @param enable true to maintains parallelism
846		*/
847		public void setMaintainsParallelism(boolean enable) {
#	Line 866 | Line 899 | public class ForkJoinPool extends Abstra
899		* Returns an estimate of the number of threads that are currently
900		* stealing or executing tasks. This method may overestimate the
901		* number of active threads.
902	+	*
903		* @return the number of active threads
904		*/
905		public int getActiveThreadCount() {
#	Line 876 | Line 910 | public class ForkJoinPool extends Abstra
910		* Returns an estimate of the number of threads that are currently
911		* idle waiting for tasks. This method may underestimate the
912		* number of idle threads.
913	+	*
914		* @return the number of idle threads
915		*/
916		final int getIdleThreadCount() {
917		int c = runningCountOf(workerCounts) - activeCountOf(runControl);
918	<	return (c <= 0)? 0 : c;
918	>	return (c <= 0) ? 0 : c;
919		}
920
921		/**
922		* Returns true if all worker threads are currently idle. An idle
923		* worker is one that cannot obtain a task to execute because none
924		* are available to steal from other threads, and there are no
925	<	* pending submissions to the pool. This method is conservative:
926	<	* It might not return true immediately upon idleness of all
925	>	* pending submissions to the pool. This method is conservative;
926	>	* it might not return true immediately upon idleness of all
927		* threads, but will eventually become true if threads remain
928		* inactive.
929	+	*
930		* @return true if all threads are currently idle
931		*/
932		public boolean isQuiescent() {
#	Line 902 | Line 938 | public class ForkJoinPool extends Abstra
938		* one thread's work queue by another. The reported value
939		* underestimates the actual total number of steals when the pool
940		* is not quiescent. This value may be useful for monitoring and
941	<	* tuning fork/join programs: In general, steal counts should be
941	>	* tuning fork/join programs: in general, steal counts should be
942		* high enough to keep threads busy, but low enough to avoid
943		* overhead and contention across threads.
944	+	*
945		* @return the number of steals
946		*/
947		public long getStealCount() {
#	Line 912 | Line 949 | public class ForkJoinPool extends Abstra
949		}
950
951		/**
952	<	* Accumulate steal count from a worker. Call only
953	<	* when worker known to be idle.
952	>	* Accumulates steal count from a worker.
953	>	* Call only when worker known to be idle.
954		*/
955		private void updateStealCount(ForkJoinWorkerThread w) {
956		int sc = w.getAndClearStealCount();
#	Line 928 | Line 965 | public class ForkJoinPool extends Abstra
965		* an approximation, obtained by iterating across all threads in
966		* the pool. This method may be useful for tuning task
967		* granularities.
968	+	*
969		* @return the number of queued tasks
970		*/
971		public long getQueuedTaskCount() {
#	Line 947 | Line 985 | public class ForkJoinPool extends Abstra
985		* Returns an estimate of the number tasks submitted to this pool
986		* that have not yet begun executing. This method takes time
987		* proportional to the number of submissions.
988	+	*
989		* @return the number of queued submissions
990		*/
991		public int getQueuedSubmissionCount() {
#	Line 956 | Line 995 | public class ForkJoinPool extends Abstra
995		/**
996		* Returns true if there are any tasks submitted to this pool
997		* that have not yet begun executing.
998	+	*
999		* @return {@code true} if there are any queued submissions
1000		*/
1001		public boolean hasQueuedSubmissions() {
#	Line 966 | Line 1006 | public class ForkJoinPool extends Abstra
1006		* Removes and returns the next unexecuted submission if one is
1007		* available.  This method may be useful in extensions to this
1008		* class that re-assign work in systems with multiple pools.
1009	+	*
1010		* @return the next submission, or null if none
1011		*/
1012		protected ForkJoinTask<?> pollSubmission() {
#	Line 985 | Line 1026 | public class ForkJoinPool extends Abstra
1026		* exception is thrown.  The behavior of this operation is
1027		* undefined if the specified collection is modified while the
1028		* operation is in progress.
1029	+	*
1030		* @param c the collection to transfer elements into
1031		* @return the number of elements transferred
1032		*/
#	Line 1045 | Line 1087 | public class ForkJoinPool extends Abstra
1087		* Invocation has no additional effect if already shut down.
1088		* Tasks that are in the process of being submitted concurrently
1089		* during the course of this method may or may not be rejected.
1090	+	*
1091		* @throws SecurityException if a security manager exists and
1092		*         the caller is not permitted to modify threads
1093		*         because it does not hold {@link
1094	<	*         java.lang.RuntimePermission}{@code ("modifyThread")},
1094	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1095		*/
1096		public void shutdown() {
1097		checkPermission();
#	Line 1066 | Line 1109 | public class ForkJoinPool extends Abstra
1109		* upon termination, so always returns an empty list. However, you
1110		* can use method {@code drainTasksTo} before invoking this
1111		* method to transfer unexecuted tasks to another collection.
1112	+	*
1113		* @return an empty list
1114		* @throws SecurityException if a security manager exists and
1115		*         the caller is not permitted to modify threads
1116		*         because it does not hold {@link
1117	<	*         java.lang.RuntimePermission}{@code ("modifyThread")},
1117	>	*         java.lang.RuntimePermission}{@code ("modifyThread")}
1118		*/
1119		public List<Runnable> shutdownNow() {
1120		checkPermission();
#	Line 1138 | Line 1182 | public class ForkJoinPool extends Abstra
1182		// Shutdown and termination support
1183
1184		/**
1185	<	* Callback from terminating worker. Null out the corresponding
1186	<	* workers slot, and if terminating, try to terminate, else try to
1187	<	* shrink workers array.
1185	>	* Callback from terminating worker. Nulls out the corresponding
1186	>	* workers slot, and if terminating, tries to terminate; else
1187	>	* tries to shrink workers array.
1188	>	*
1189		* @param w the worker
1190		*/
1191		final void workerTerminated(ForkJoinWorkerThread w) {
#	Line 1171 | Line 1216 | public class ForkJoinPool extends Abstra
1216		}
1217
1218		/**
1219	<	* Initiate termination.
1219	>	* Initiates termination.
1220		*/
1221		private void terminate() {
1222		if (transitionRunStateTo(TERMINATING)) {
#	Line 1348 | Line 1393 | public class ForkJoinPool extends Abstra
1393		* Ensures that no thread is waiting for count to advance from the
1394		* current value of eventCount read on entry to this method, by
1395		* releasing waiting threads if necessary.
1396	+	*
1397		* @return the count
1398		*/
1399		final long ensureSync() {
#	Line 1369 | Line 1415 | public class ForkJoinPool extends Abstra
1415		*/
1416		private void signalIdleWorkers() {
1417		long c;
1418	<	do;while (!casEventCount(c = eventCount, c+1));
1418	>	do {} while (!casEventCount(c = eventCount, c+1));
1419		ensureSync();
1420		}
1421
#	Line 1393 | Line 1439 | public class ForkJoinPool extends Abstra
1439		* Waits until event count advances from last value held by
1440		* caller, or if excess threads, caller is resumed as spare, or
1441		* caller or pool is terminating. Updates caller's event on exit.
1442	+	*
1443		* @param w the calling worker thread
1444		*/
1445		final void sync(ForkJoinWorkerThread w) {
#	Line 1423 | Line 1470 | public class ForkJoinPool extends Abstra
1470		* Returns true if worker waiting on sync can proceed:
1471		*  - on signal (thread == null)
1472		*  - on event count advance (winning race to notify vs signaller)
1473	<	*  - on Interrupt
1473	>	*  - on interrupt
1474		*  - if the first queued node, we find work available
1475		* If node was not signalled and event count not advanced on exit,
1476		* then we also help advance event count.
1477	+	*
1478		* @return true if node can be released
1479		*/
1480		final boolean syncIsReleasable(WaitQueueNode node) {
#	Line 1467 | Line 1515 | public class ForkJoinPool extends Abstra
1515		* spare thread when one is about to block (and remove or
1516		* suspend it later when unblocked -- see suspendIfSpare).
1517		* However, implementing this idea requires coping with
1518	<	* several problems: We have imperfect information about the
1518	>	* several problems: we have imperfect information about the
1519		* states of threads. Some count updates can and usually do
1520		* lag run state changes, despite arrangements to keep them
1521		* accurate (for example, when possible, updating counts
#	Line 1490 | Line 1538 | public class ForkJoinPool extends Abstra
1538		* target counts, else create only to avoid starvation
1539		* @return true if joinMe known to be done
1540		*/
1541	<	final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) {
1541	>	final boolean preJoin(ForkJoinTask<?> joinMe,
1542	>	boolean maintainParallelism) {
1543		maintainParallelism &= maintainsParallelism; // overrride
1544		boolean dec = false;  // true when running count decremented
1545		while (spareStack == null || !tryResumeSpare(dec)) {
1546		int counts = workerCounts;
1547	<	if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat
1547	>	if (dec || (dec = casWorkerCounts(counts, --counts))) {
1548	>	// CAS cheat
1549		if (!needSpare(counts, maintainParallelism))
1550		break;
1551		if (joinMe.status < 0)
#	Line 1510 | Line 1560 | public class ForkJoinPool extends Abstra
1560		/**
1561		* Same idea as preJoin
1562		*/
1563	<	final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){
1563	>	final boolean preBlock(ManagedBlocker blocker,
1564	>	boolean maintainParallelism) {
1565		maintainParallelism &= maintainsParallelism;
1566		boolean dec = false;
1567		while (spareStack == null || !tryResumeSpare(dec)) {
#	Line 1534 | Line 1585 | public class ForkJoinPool extends Abstra
1585		* there is apparently some work to do.  This self-limiting rule
1586		* means that the more threads that have already been added, the
1587		* less parallelism we will tolerate before adding another.
1588	+	*
1589		* @param counts current worker counts
1590		* @param maintainParallelism try to maintain parallelism
1591		*/
#	Line 1553 | Line 1605 | public class ForkJoinPool extends Abstra
1605		/**
1606		* Adds a spare worker if lock available and no more than the
1607		* expected numbers of threads exist.
1608	+	*
1609		* @return true if successful
1610		*/
1611		private boolean tryAddSpare(int expectedCounts) {
#	Line 1612 | Line 1665 | public class ForkJoinPool extends Abstra
1665		* the same WaitQueueNodes as barriers.  They are resumed mainly
1666		* in preJoin, but are also woken on pool events that require all
1667		* threads to check run state.
1668	+	*
1669		* @param w the caller
1670		*/
1671		private boolean suspendIfSpare(ForkJoinWorkerThread w) {
#	Line 1622 | Line 1676 | public class ForkJoinPool extends Abstra
1676		node = new WaitQueueNode(0, w);
1677		if (casWorkerCounts(s, s-1)) { // representation-dependent
1678		// push onto stack
1679	<	do;while (!casSpareStack(node.next = spareStack, node));
1679	>	do {} while (!casSpareStack(node.next = spareStack, node));
1680		// block until released by resumeSpare
1681		node.awaitSpareRelease();
1682		return true;
#	Line 1633 | Line 1687 | public class ForkJoinPool extends Abstra
1687
1688		/**
1689		* Tries to pop and resume a spare thread.
1690	+	*
1691		* @param updateCount if true, increment running count on success
1692		* @return true if successful
1693		*/
#	Line 1651 | Line 1706 | public class ForkJoinPool extends Abstra
1706
1707		/**
1708		* Pops and resumes all spare threads. Same idea as ensureSync.
1709	+	*
1710		* @return true if any spares released
1711		*/
1712		private boolean resumeAllSpares() {
#	Line 1694 | Line 1750 | public class ForkJoinPool extends Abstra
1750		* Interface for extending managed parallelism for tasks running
1751		* in ForkJoinPools. A ManagedBlocker provides two methods.
1752		* Method {@code isReleasable} must return true if blocking is not
1753	<	* necessary. Method {@code block} blocks the current thread
1754	<	* if necessary (perhaps internally invoking isReleasable before
1755	<	* actually blocking.).
1753	>	* necessary. Method {@code block} blocks the current thread if
1754	>	* necessary (perhaps internally invoking {@code isReleasable}
1755	>	* before actually blocking.).
1756	>	*
1757		* <p>For example, here is a ManagedBlocker based on a
1758		* ReentrantLock:
1759	<	* <pre>
1760	<	*   class ManagedLocker implements ManagedBlocker {
1761	<	*     final ReentrantLock lock;
1762	<	*     boolean hasLock = false;
1763	<	*     ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1764	<	*     public boolean block() {
1765	<	*        if (!hasLock)
1766	<	*           lock.lock();
1767	<	*        return true;
1768	<	*     }
1769	<	*     public boolean isReleasable() {
1770	<	*        return hasLock || (hasLock = lock.tryLock());
1714	<	*     }
1759	>	*  <pre> {@code
1760	>	* class ManagedLocker implements ManagedBlocker {
1761	>	*   final ReentrantLock lock;
1762	>	*   boolean hasLock = false;
1763	>	*   ManagedLocker(ReentrantLock lock) { this.lock = lock; }
1764	>	*   public boolean block() {
1765	>	*     if (!hasLock)
1766	>	*       lock.lock();
1767	>	*     return true;
1768	>	*   }
1769	>	*   public boolean isReleasable() {
1770	>	*     return hasLock || (hasLock = lock.tryLock());
1771		*   }
1772	<	* </pre>
1772	>	* }}</pre>
1773		*/
1774		public static interface ManagedBlocker {
1775		/**
1776		* Possibly blocks the current thread, for example waiting for
1777		* a lock or condition.
1778	+	*
1779		* @return true if no additional blocking is necessary (i.e.,
1780		* if isReleasable would return true)
1781		* @throws InterruptedException if interrupted while waiting
1782	<	* (the method is not required to do so, but is allowed to).
1782	>	* (the method is not required to do so, but is allowed to)
1783		*/
1784		boolean block() throws InterruptedException;
1785
#	Line 1739 | Line 1796 | public class ForkJoinPool extends Abstra
1796		* while the current thread is blocked.  If
1797		* {@code maintainParallelism} is true and the pool supports
1798		* it ({@link #getMaintainsParallelism}), this method attempts to
1799	<	* maintain the pool's nominal parallelism. Otherwise if activates
1799	>	* maintain the pool's nominal parallelism. Otherwise it activates
1800		* a thread only if necessary to avoid complete starvation. This
1801		* option may be preferable when blockages use timeouts, or are
1802		* almost always brief.
1803		*
1804		* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1805		* equivalent to
1806	<	* <pre>
1807	<	*   while (!blocker.isReleasable())
1808	<	*      if (blocker.block())
1809	<	*         return;
1810	<	* </pre>
1806	>	*  <pre> {@code
1807	>	* while (!blocker.isReleasable())
1808	>	*   if (blocker.block())
1809	>	*     return;
1810	>	* }</pre>
1811		* If the caller is a ForkJoinTask, then the pool may first
1812		* be expanded to ensure parallelism, and later adjusted.
1813		*
#	Line 1765 | Line 1822 | public class ForkJoinPool extends Abstra
1822		boolean maintainParallelism)
1823		throws InterruptedException {
1824		Thread t = Thread.currentThread();
1825	<	ForkJoinPool pool = (t instanceof ForkJoinWorkerThread?
1826	<	((ForkJoinWorkerThread)t).pool : null);
1825	>	ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ?
1826	>	((ForkJoinWorkerThread) t).pool : null);
1827		if (!blocker.isReleasable()) {
1828		try {
1829		if (pool == null ||
#	Line 1781 | Line 1838 | public class ForkJoinPool extends Abstra
1838
1839		private static void awaitBlocker(ManagedBlocker blocker)
1840		throws InterruptedException {
1841	<	do;while (!blocker.isReleasable() && !blocker.block());
1841	>	do {} while (!blocker.isReleasable() && !blocker.block());
1842		}
1843
1844		// AbstractExecutorService overrides
1845
1846		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1847	<	return new AdaptedRunnable(runnable, value);
1847	>	return new AdaptedRunnable<T>(runnable, value);
1848		}
1849
1850		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1851	<	return new AdaptedCallable(callable);
1851	>	return new AdaptedCallable<T>(callable);
1852		}
1853
1854
1855	<	// Temporary Unsafe mechanics for preliminary release
1856	<	private static Unsafe getUnsafe() throws Throwable {
1855	>	// Unsafe mechanics for jsr166y 3rd party package.
1856	>	private static sun.misc.Unsafe getUnsafe() {
1857		try {
1858	<	return Unsafe.getUnsafe();
1858	>	return sun.misc.Unsafe.getUnsafe();
1859		} catch (SecurityException se) {
1860		try {
1861		return java.security.AccessController.doPrivileged
1862	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1863	<	public Unsafe run() throws Exception {
1864	<	return getUnsafePrivileged();
1862	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1863	>	public sun.misc.Unsafe run() throws Exception {
1864	>	return getUnsafeByReflection();
1865		}});
1866		} catch (java.security.PrivilegedActionException e) {
1867	<	throw e.getCause();
1867	>	throw new RuntimeException("Could not initialize intrinsics",
1868	>	e.getCause());
1869		}
1870		}
1871		}
1872
1873	<	private static Unsafe getUnsafePrivileged()
1873	>	private static sun.misc.Unsafe getUnsafeByReflection()
1874		throws NoSuchFieldException, IllegalAccessException {
1875	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1875	>	java.lang.reflect.Field f =
1876	>	sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
1877		f.setAccessible(true);
1878	<	return (Unsafe) f.get(null);
1820	<	}
1821	<
1822	<	private static long fieldOffset(String fieldName)
1823	<	throws NoSuchFieldException {
1824	<	return UNSAFE.objectFieldOffset
1825	<	(ForkJoinPool.class.getDeclaredField(fieldName));
1878	>	return (sun.misc.Unsafe) f.get(null);
1879		}
1880
1881	<	static final Unsafe UNSAFE;
1829	<	static final long eventCountOffset;
1830	<	static final long workerCountsOffset;
1831	<	static final long runControlOffset;
1832	<	static final long syncStackOffset;
1833	<	static final long spareStackOffset;
1834	<
1835	<	static {
1881	>	private static long fieldOffset(String fieldName, Class<?> klazz) {
1882		try {
1883	<	UNSAFE = getUnsafe();
1884	<	eventCountOffset = fieldOffset("eventCount");
1885	<	workerCountsOffset = fieldOffset("workerCounts");
1886	<	runControlOffset = fieldOffset("runControl");
1887	<	syncStackOffset = fieldOffset("syncStack");
1888	<	spareStackOffset = fieldOffset("spareStack");
1843	<	} catch (Throwable e) {
1844	<	throw new RuntimeException("Could not initialize intrinsics", e);
1883	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName));
1884	>	} catch (NoSuchFieldException e) {
1885	>	// Convert Exception to Error
1886	>	NoSuchFieldError error = new NoSuchFieldError(fieldName);
1887	>	error.initCause(e);
1888	>	throw error;
1889		}
1890		}
1891
1892	+	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1893	+	static final long eventCountOffset =
1894	+	fieldOffset("eventCount", ForkJoinPool.class);
1895	+	static final long workerCountsOffset =
1896	+	fieldOffset("workerCounts", ForkJoinPool.class);
1897	+	static final long runControlOffset =
1898	+	fieldOffset("runControl", ForkJoinPool.class);
1899	+	static final long syncStackOffset =
1900	+	fieldOffset("syncStack",ForkJoinPool.class);
1901	+	static final long spareStackOffset =
1902	+	fieldOffset("spareStack", ForkJoinPool.class);
1903	+
1904		private boolean casEventCount(long cmp, long val) {
1905		return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
1906		}

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines