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Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.8 by jsr166, Mon Jul 20 21:54:51 2009 UTC vs.
Revision 1.29 by jsr166, Sun Aug 2 17:19:24 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import java.io.Serializable;
9	<	import java.util.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.atomic.*;
11	<	import sun.misc.Unsafe;
12	<	import java.lang.reflect.*;
10	>
11	>	import java.io.Serializable;
12	>	import java.util.Collection;
13	>	import java.util.Collections;
14	>	import java.util.List;
15	>	import java.util.Map;
16	>	import java.util.WeakHashMap;
17
18		/**
19	<	* Abstract base class for tasks that run within a {@link
20	<	* ForkJoinPool}.  A ForkJoinTask is a thread-like entity that is much
19	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
20	>	* A {@code ForkJoinTask} is a thread-like entity that is much
21		* lighter weight than a normal thread.  Huge numbers of tasks and
22		* subtasks may be hosted by a small number of actual threads in a
23		* ForkJoinPool, at the price of some usage limitations.
24		*
25	<	* <p> A "main" ForkJoinTask begins execution when submitted to a
26	<	* {@link ForkJoinPool}. Once started, it will usually in turn start
27	<	* other subtasks.  As indicated by the name of this class, many
28	<	* programs using ForkJoinTasks employ only methods {@code fork}
29	<	* and {@code join}, or derivatives such as
30	<	* {@code invokeAll}.  However, this class also provides a number
31	<	* of other methods that can come into play in advanced usages, as
32	<	* well as extension mechanics that allow support of new forms of
33	<	* fork/join processing.
25	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
26	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
27	>	* start other subtasks.  As indicated by the name of this class,
28	>	* many programs using {@code ForkJoinTask} employ only methods
29	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
30	>	* #invokeAll}.  However, this class also provides a number of other
31	>	* methods that can come into play in advanced usages, as well as
32	>	* extension mechanics that allow support of new forms of fork/join
33	>	* processing.
34		*
35	<	* <p>A ForkJoinTask is a lightweight form of {@link Future}.  The
36	<	* efficiency of ForkJoinTasks stems from a set of restrictions (that
37	<	* are only partially statically enforceable) reflecting their
38	<	* intended use as computational tasks calculating pure functions or
39	<	* operating on purely isolated objects.  The primary coordination
40	<	* mechanisms are {@link #fork}, that arranges asynchronous execution,
41	<	* and {@link #join}, that doesn't proceed until the task's result has
42	<	* been computed.  Computations should avoid {@code synchronized}
43	<	* methods or blocks, and should minimize other blocking
44	<	* synchronization apart from joining other tasks or using
45	<	* synchronizers such as Phasers that are advertised to cooperate with
46	<	* fork/join scheduling. Tasks should also not perform blocking IO,
47	<	* and should ideally access variables that are completely independent
48	<	* of those accessed by other running tasks. Minor breaches of these
49	<	* restrictions, for example using shared output streams, may be
50	<	* tolerable in practice, but frequent use may result in poor
51	<	* performance, and the potential to indefinitely stall if the number
52	<	* of threads not waiting for IO or other external synchronization
53	<	* becomes exhausted. This usage restriction is in part enforced by
54	<	* not permitting checked exceptions such as {@code IOExceptions}
55	<	* to be thrown. However, computations may still encounter unchecked
56	<	* exceptions, that are rethrown to callers attempting join
57	<	* them. These exceptions may additionally include
58	<	* RejectedExecutionExceptions stemming from internal resource
59	<	* exhaustion such as failure to allocate internal task queues.
35	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
36	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
37	>	* restrictions (that are only partially statically enforceable)
38	>	* reflecting their intended use as computational tasks calculating
39	>	* pure functions or operating on purely isolated objects.  The
40	>	* primary coordination mechanisms are {@link #fork}, that arranges
41	>	* asynchronous execution, and {@link #join}, that doesn't proceed
42	>	* until the task's result has been computed.  Computations should
43	>	* avoid {@code synchronized} methods or blocks, and should minimize
44	>	* other blocking synchronization apart from joining other tasks or
45	>	* using synchronizers such as Phasers that are advertised to
46	>	* cooperate with fork/join scheduling. Tasks should also not perform
47	>	* blocking IO, and should ideally access variables that are
48	>	* completely independent of those accessed by other running
49	>	* tasks. Minor breaches of these restrictions, for example using
50	>	* shared output streams, may be tolerable in practice, but frequent
51	>	* use may result in poor performance, and the potential to
52	>	* indefinitely stall if the number of threads not waiting for IO or
53	>	* other external synchronization becomes exhausted. This usage
54	>	* restriction is in part enforced by not permitting checked
55	>	* exceptions such as {@code IOExceptions} to be thrown. However,
56	>	* computations may still encounter unchecked exceptions, that are
57	>	* rethrown to callers attempting join them. These exceptions may
58	>	* additionally include RejectedExecutionExceptions stemming from
59	>	* internal resource exhaustion such as failure to allocate internal
60	>	* task queues.
61		*
62		* <p>The primary method for awaiting completion and extracting
63		* results of a task is {@link #join}, but there are several variants:
#	Line 72 | Line 76 | import java.lang.reflect.*;
76		* performs the most common form of parallel invocation: forking a set
77		* of tasks and joining them all.
78		*
79	<	* <p> The ForkJoinTask class is not usually directly subclassed.
79	>	* <p>The ForkJoinTask class is not usually directly subclassed.
80		* Instead, you subclass one of the abstract classes that support a
81	<	* particular style of fork/join processing.  Normally, a concrete
81	>	* particular style of fork/join processing, typically {@link
82	>	* RecursiveAction} for computations that do not return results, or
83	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
84		* ForkJoinTask subclass declares fields comprising its parameters,
85		* established in a constructor, and then defines a {@code compute}
86		* method that somehow uses the control methods supplied by this base
87		* class. While these methods have {@code public} access (to allow
88		* instances of different task subclasses to call each others
89		* methods), some of them may only be called from within other
90	<	* ForkJoinTasks. Attempts to invoke them in other contexts result in
91	<	* exceptions or errors possibly including ClassCastException.
90	>	* ForkJoinTasks (as may be determined using method {@link
91	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
92	>	* result in exceptions or errors, possibly including
93	>	* ClassCastException.
94		*
95		* <p>Most base support methods are {@code final} because their
96		* implementations are intrinsically tied to the underlying
97		* lightweight task scheduling framework, and so cannot be overridden.
98		* Developers creating new basic styles of fork/join processing should
99		* minimally implement {@code protected} methods
100	<	* {@code exec}, {@code setRawResult}, and
101	<	* {@code getRawResult}, while also introducing an abstract
100	>	* {@link #exec}, {@link #setRawResult}, and
101	>	* {@link #getRawResult}, while also introducing an abstract
102		* computational method that can be implemented in its subclasses,
103		* possibly relying on other {@code protected} methods provided
104		* by this class.
105		*
106		* <p>ForkJoinTasks should perform relatively small amounts of
107	<	* computations, othewise splitting into smaller tasks. As a very
107	>	* computations, otherwise splitting into smaller tasks. As a very
108		* rough rule of thumb, a task should perform more than 100 and less
109		* than 10000 basic computational steps. If tasks are too big, then
110	<	* parellelism cannot improve throughput. If too small, then memory
110	>	* parallelism cannot improve throughput. If too small, then memory
111		* and internal task maintenance overhead may overwhelm processing.
112		*
113	+	* <p>This class provides {@code adapt} methods for {@link
114	+	* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that
115	+	* may be of use when mixing execution of ForkJoinTasks with other
116	+	* kinds of tasks. When all tasks are of this form, consider using a
117	+	* pool in {@link ForkJoinPool#setAsyncMode}.
118	+	*
119		* <p>ForkJoinTasks are {@code Serializable}, which enables them
120		* to be used in extensions such as remote execution frameworks. It is
121		* in general sensible to serialize tasks only before or after, but
122		* not during execution. Serialization is not relied on during
123		* execution itself.
124	+	*
125	+	* @since 1.7
126	+	* @author Doug Lea
127		*/
128		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
129
#	Line 128 | Line 145 | public abstract class ForkJoinTask<V> im
145		* currently unused. Also value 0x80000000 is available as spare
146		* completion value.
147		*/
148	<	volatile int status; // accessed directy by pool and workers
148	>	volatile int status; // accessed directly by pool and workers
149
150		static final int COMPLETION_MASK      = 0xe0000000;
151		static final int NORMAL               = 0xe0000000; // == mask
#	Line 141 | Line 158 | public abstract class ForkJoinTask<V> im
158		/**
159		* Table of exceptions thrown by tasks, to enable reporting by
160		* callers. Because exceptions are rare, we don't directly keep
161	<	* them with task objects, but instead us a weak ref table.  Note
161	>	* them with task objects, but instead use a weak ref table.  Note
162		* that cancellation exceptions don't appear in the table, but are
163		* instead recorded as status values.
164	<	* Todo: Use ConcurrentReferenceHashMap
164	>	* TODO: Use ConcurrentReferenceHashMap
165		*/
166		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
167		Collections.synchronizedMap
#	Line 153 | Line 170 | public abstract class ForkJoinTask<V> im
170		// within-package utilities
171
172		/**
173	<	* Get current worker thread, or null if not a worker thread
173	>	* Gets current worker thread, or null if not a worker thread.
174		*/
175		static ForkJoinWorkerThread getWorker() {
176		Thread t = Thread.currentThread();
177	<	return ((t instanceof ForkJoinWorkerThread)?
178	<	(ForkJoinWorkerThread)t : null);
177	>	return ((t instanceof ForkJoinWorkerThread) ?
178	>	(ForkJoinWorkerThread) t : null);
179		}
180
181		final boolean casStatus(int cmp, int val) {
182	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
182	>	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
183		}
184
185		/**
#	Line 170 | Line 187 | public abstract class ForkJoinTask<V> im
187		*/
188		static void rethrowException(Throwable ex) {
189		if (ex != null)
190	<	_unsafe.throwException(ex);
190	>	UNSAFE.throwException(ex);
191		}
192
193		// Setting completion status
194
195		/**
196	<	* Mark completion and wake up threads waiting to join this task.
196	>	* Marks completion and wakes up threads waiting to join this task.
197	>	*
198		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
199		*/
200		final void setCompletion(int completion) {
201		ForkJoinPool pool = getPool();
202		if (pool != null) {
203		int s; // Clear signal bits while setting completion status
204	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
204	>	do {} while ((s = status) >= 0 && !casStatus(s, completion));
205
206		if ((s & SIGNAL_MASK) != 0) {
207		if ((s &= INTERNAL_SIGNAL_MASK) != 0)
208		pool.updateRunningCount(s);
209	<	synchronized(this) { notifyAll(); }
209	>	synchronized (this) { notifyAll(); }
210		}
211		}
212		else
#	Line 201 | Line 219 | public abstract class ForkJoinTask<V> im
219		*/
220		private void externallySetCompletion(int completion) {
221		int s;
222	<	do;while ((s = status) >= 0 &&
223	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
224	<	synchronized(this) { notifyAll(); }
222	>	do {} while ((s = status) >= 0 &&
223	>	!casStatus(s, (s & SIGNAL_MASK) | completion));
224	>	synchronized (this) { notifyAll(); }
225		}
226
227		/**
228	<	* Sets status to indicate normal completion
228	>	* Sets status to indicate normal completion.
229		*/
230		final void setNormalCompletion() {
231		// Try typical fast case -- single CAS, no signal, not already done.
232		// Manually expand casStatus to improve chances of inlining it
233	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
233	>	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
234		setCompletion(NORMAL);
235		}
236
237		// internal waiting and notification
238
239		/**
240	<	* Performs the actual monitor wait for awaitDone
240	>	* Performs the actual monitor wait for awaitDone.
241		*/
242		private void doAwaitDone() {
243		// Minimize lock bias and in/de-flation effects by maximizing
244		// chances of waiting inside sync
245		try {
246		while (status >= 0)
247	<	synchronized(this) { if (status >= 0) wait(); }
247	>	synchronized (this) { if (status >= 0) wait(); }
248		} catch (InterruptedException ie) {
249		onInterruptedWait();
250		}
251		}
252
253		/**
254	<	* Performs the actual monitor wait for awaitDone
254	>	* Performs the actual timed monitor wait for awaitDone.
255		*/
256		private void doAwaitDone(long startTime, long nanos) {
257	<	synchronized(this) {
257	>	synchronized (this) {
258		try {
259		while (status >= 0) {
260	<	long nt = nanos - System.nanoTime() - startTime;
260	>	long nt = nanos - (System.nanoTime() - startTime);
261		if (nt <= 0)
262		break;
263	<	wait(nt / 1000000, (int)(nt % 1000000));
263	>	wait(nt / 1000000, (int) (nt % 1000000));
264		}
265		} catch (InterruptedException ie) {
266		onInterruptedWait();
#	Line 255 | Line 273 | public abstract class ForkJoinTask<V> im
273		/**
274		* Sets status to indicate there is joiner, then waits for join,
275		* surrounded with pool notifications.
276	+	*
277		* @return status upon exit
278		*/
279	<	private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
280	<	ForkJoinPool pool = w == null? null : w.pool;
279	>	private int awaitDone(ForkJoinWorkerThread w,
280	>	boolean maintainParallelism) {
281	>	ForkJoinPool pool = (w == null) ? null : w.pool;
282		int s;
283		while ((s = status) >= 0) {
284	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
284	>	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
285		if (pool == null || !pool.preJoin(this, maintainParallelism))
286		doAwaitDone();
287		if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
#	Line 274 | Line 294 | public abstract class ForkJoinTask<V> im
294
295		/**
296		* Timed version of awaitDone
297	+	*
298		* @return status upon exit
299		*/
300		private int awaitDone(ForkJoinWorkerThread w, long nanos) {
301	<	ForkJoinPool pool = w == null? null : w.pool;
301	>	ForkJoinPool pool = (w == null) ? null : w.pool;
302		int s;
303		while ((s = status) >= 0) {
304	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
304	>	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
305		long startTime = System.nanoTime();
306		if (pool == null || !pool.preJoin(this, false))
307		doAwaitDone(startTime, nanos);
#	Line 297 | Line 318 | public abstract class ForkJoinTask<V> im
318		}
319
320		/**
321	<	* Notify pool that thread is unblocked. Called by signalled
321	>	* Notifies pool that thread is unblocked. Called by signalled
322		* threads when woken by non-FJ threads (which is atypical).
323		*/
324		private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
325		int s;
326	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
326	>	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
327		if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
328		pool.updateRunningCount(s);
329		}
330
331		/**
332	<	* Notify pool to adjust counts on cancelled or timed out wait
332	>	* Notifies pool to adjust counts on cancelled or timed out wait.
333		*/
334		private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
335		if (pool != null) {
#	Line 323 | Line 344 | public abstract class ForkJoinTask<V> im
344		}
345
346		/**
347	<	* Handle interruptions during waits.
347	>	* Handles interruptions during waits.
348		*/
349		private void onInterruptedWait() {
350		ForkJoinWorkerThread w = getWorker();
#	Line 342 | Line 363 | public abstract class ForkJoinTask<V> im
363		}
364
365		/**
366	<	* Throws the exception associated with status s;
366	>	* Throws the exception associated with status s.
367	>	*
368		* @throws the exception
369		*/
370		private void reportException(int s) {
#	Line 355 | Line 377 | public abstract class ForkJoinTask<V> im
377		}
378
379		/**
380	<	* Returns result or throws exception using j.u.c.Future conventions
381	<	* Only call when isDone known to be true.
380	>	* Returns result or throws exception using j.u.c.Future conventions.
381	>	* Only call when {@code isDone} known to be true.
382		*/
383		private V reportFutureResult()
384		throws ExecutionException, InterruptedException {
#	Line 375 | Line 397 | public abstract class ForkJoinTask<V> im
397
398		/**
399		* Returns result or throws exception using j.u.c.Future conventions
400	<	* with timeouts
400	>	* with timeouts.
401		*/
402		private V reportTimedFutureResult()
403		throws InterruptedException, ExecutionException, TimeoutException {
#	Line 396 | Line 418 | public abstract class ForkJoinTask<V> im
418
419		/**
420		* Calls exec, recording completion, and rethrowing exception if
421	<	* encountered. Caller should normally check status before calling
421	>	* encountered. Caller should normally check status before calling.
422	>	*
423		* @return true if completed normally
424		*/
425		private boolean tryExec() {
#	Line 414 | Line 437 | public abstract class ForkJoinTask<V> im
437
438		/**
439		* Main execution method used by worker threads. Invokes
440	<	* base computation unless already complete
440	>	* base computation unless already complete.
441		*/
442		final void quietlyExec() {
443		if (status >= 0) {
444		try {
445		if (!exec())
446		return;
447	<	} catch(Throwable rex) {
447	>	} catch (Throwable rex) {
448		setDoneExceptionally(rex);
449		return;
450		}
#	Line 430 | Line 453 | public abstract class ForkJoinTask<V> im
453		}
454
455		/**
456	<	* Calls exec, recording but not rethrowing exception
457	<	* Caller should normally check status before calling
456	>	* Calls exec(), recording but not rethrowing exception.
457	>	* Caller should normally check status before calling.
458	>	*
459		* @return true if completed normally
460		*/
461		private boolean tryQuietlyInvoke() {
#	Line 447 | Line 471 | public abstract class ForkJoinTask<V> im
471		}
472
473		/**
474	<	* Cancel, ignoring any exceptions it throws
474	>	* Cancels, ignoring any exceptions it throws.
475		*/
476		final void cancelIgnoringExceptions() {
477		try {
478		cancel(false);
479	<	} catch(Throwable ignore) {
479	>	} catch (Throwable ignore) {
480		}
481		}
482
#	Line 464 | Line 488 | public abstract class ForkJoinTask<V> im
488		ForkJoinTask<?> t;
489		while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
490		t.quietlyExec();
491	<	return (s >= 0)? awaitDone(w, false) : s; // block if no work
491	>	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
492		}
493
494		// public methods
#	Line 474 | Line 498 | public abstract class ForkJoinTask<V> im
498		* necessarily enforced, it is a usage error to fork a task more
499		* than once unless it has completed and been reinitialized.  This
500		* method may be invoked only from within ForkJoinTask
501	<	* computations. Attempts to invoke in other contexts result in
502	<	* exceptions or errors possibly including ClassCastException.
501	>	* computations (as may be determined using method {@link
502	>	* #inForkJoinPool}). Attempts to invoke in other contexts result
503	>	* in exceptions or errors, possibly including ClassCastException.
504	>	*
505	>	* @return {@code this}, to simplify usage.
506		*/
507	<	public final void fork() {
508	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
507	>	public final ForkJoinTask<V> fork() {
508	>	((ForkJoinWorkerThread) Thread.currentThread())
509	>	.pushTask(this);
510	>	return this;
511		}
512
513		/**
#	Line 499 | Line 528 | public abstract class ForkJoinTask<V> im
528		/**
529		* Commences performing this task, awaits its completion if
530		* necessary, and return its result.
531	+	*
532		* @throws Throwable (a RuntimeException, Error, or unchecked
533	<	* exception) if the underlying computation did so.
533	>	* exception) if the underlying computation did so
534		* @return the computed result
535		*/
536		public final V invoke() {
#	Line 511 | Line 541 | public abstract class ForkJoinTask<V> im
541		}
542
543		/**
544	<	* Forks both tasks, returning when {@code isDone} holds for
545	<	* both of them or an exception is encountered. This method may be
546	<	* invoked only from within ForkJoinTask computations. Attempts to
547	<	* invoke in other contexts result in exceptions or errors
544	>	* Forks the given tasks, returning when {@code isDone} holds for
545	>	* each task or an exception is encountered. This method may be
546	>	* invoked only from within ForkJoinTask computations (as may be
547	>	* determined using method {@link #inForkJoinPool}). Attempts to
548	>	* invoke in other contexts result in exceptions or errors,
549		* possibly including ClassCastException.
550	<	* @param t1 one task
551	<	* @param t2 the other task
552	<	* @throws NullPointerException if t1 or t2 are null
553	<	* @throws RuntimeException or Error if either task did so.
550	>	*
551	>	* @param t1 the first task
552	>	* @param t2 the second task
553	>	* @throws NullPointerException if any task is null
554	>	* @throws RuntimeException or Error if a task did so
555		*/
556		public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
557		t2.fork();
#	Line 528 | Line 560 | public abstract class ForkJoinTask<V> im
560		}
561
562		/**
563	<	* Forks the given tasks, returning when {@code isDone} holds
564	<	* for all of them. If any task encounters an exception, others
565	<	* may be cancelled.  This method may be invoked only from within
566	<	* ForkJoinTask computations. Attempts to invoke in other contexts
567	<	* result in exceptions or errors possibly including ClassCastException.
568	<	* @param tasks the array of tasks
569	<	* @throws NullPointerException if tasks or any element are null.
570	<	* @throws RuntimeException or Error if any task did so.
563	>	* Forks the given tasks, returning when {@code isDone} holds for
564	>	* each task or an exception is encountered. If any task
565	>	* encounters an exception, others may be, but are not guaranteed
566	>	* to be, cancelled.  This method may be invoked only from within
567	>	* ForkJoinTask computations (as may be determined using method
568	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
569	>	* result in exceptions or errors, possibly including
570	>	* ClassCastException.
571	>	*
572	>	* Overloadings of this method exist for the special cases
573	>	* of one to four arguments.
574	>	*
575	>	* @param tasks the tasks
576	>	* @throws NullPointerException if tasks or any element are null
577	>	* @throws RuntimeException or Error if any task did so
578		*/
579		public static void invokeAll(ForkJoinTask<?>... tasks) {
580		Throwable ex = null;
#	Line 571 | Line 610 | public abstract class ForkJoinTask<V> im
610		}
611
612		/**
613	<	* Forks all tasks in the collection, returning when
614	<	* {@code isDone} holds for all of them. If any task
615	<	* encounters an exception, others may be cancelled.  This method
616	<	* may be invoked only from within ForkJoinTask
617	<	* computations. Attempts to invoke in other contexts resul!t in
618	<	* exceptions or errors possibly including ClassCastException.
613	>	* Forks all tasks in the collection, returning when {@code
614	>	* isDone} holds for each task or an exception is encountered. If
615	>	* any task encounters an exception, others may be, but are not
616	>	* guaranteed to be, cancelled.  This method may be invoked only
617	>	* from within ForkJoinTask computations (as may be determined
618	>	* using method {@link #inForkJoinPool}). Attempts to invoke in
619	>	* other contexts result in exceptions or errors, possibly
620	>	* including ClassCastException.
621	>	*
622		* @param tasks the collection of tasks
623	<	* @throws NullPointerException if tasks or any element are null.
624	<	* @throws RuntimeException or Error if any task did so.
625	<	*/
626	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
627	<	if (!(tasks instanceof List)) {
628	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
629	<	return;
623	>	* @return the tasks argument, to simplify usage
624	>	* @throws NullPointerException if tasks or any element are null
625	>	* @throws RuntimeException or Error if any task did so
626	>	*/
627	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
628	>	if (!(tasks instanceof List<?>)) {
629	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
630	>	return tasks;
631		}
632	+	@SuppressWarnings("unchecked")
633		List<? extends ForkJoinTask<?>> ts =
634	<	(List<? extends ForkJoinTask<?>>)tasks;
634	>	(List<? extends ForkJoinTask<?>>) tasks;
635		Throwable ex = null;
636		int last = ts.size() - 1;
637		for (int i = last; i >= 0; --i) {
#	Line 618 | Line 662 | public abstract class ForkJoinTask<V> im
662		}
663		if (ex != null)
664		rethrowException(ex);
665	+	return tasks;
666		}
667
668		/**
669	<	* Returns true if the computation performed by this task has
670	<	* completed (or has been cancelled).
671	<	* @return true if this computation has completed
669	>	* Returns {@code true} if the computation performed by this task
670	>	* has completed (or has been cancelled).
671	>	*
672	>	* @return {@code true} if this computation has completed
673		*/
674		public final boolean isDone() {
675		return status < 0;
676		}
677
678		/**
679	<	* Returns true if this task was cancelled.
680	<	* @return true if this task was cancelled
679	>	* Returns {@code true} if this task was cancelled.
680	>	*
681	>	* @return {@code true} if this task was cancelled
682		*/
683		public final boolean isCancelled() {
684		return (status & COMPLETION_MASK) == CANCELLED;
#	Line 639 | Line 686 | public abstract class ForkJoinTask<V> im
686
687		/**
688		* Asserts that the results of this task's computation will not be
689	<	* used. If a cancellation occurs before atempting to execute this
690	<	* task, then execution will be suppressed, {@code isCancelled}
691	<	* will report true, and {@code join} will result in a
689	>	* used. If a cancellation occurs before attempting to execute this
690	>	* task, execution will be suppressed, {@link #isCancelled}
691	>	* will report true, and {@link #join} will result in a
692		* {@code CancellationException} being thrown. Otherwise, when
693		* cancellation races with completion, there are no guarantees
694	<	* about whether {@code isCancelled} will report true, whether
695	<	* {@code join} will return normally or via an exception, or
696	<	* whether these behaviors will remain consistent upon repeated
694	>	* about whether {@code isCancelled} will report {@code true},
695	>	* whether {@code join} will return normally or via an exception,
696	>	* or whether these behaviors will remain consistent upon repeated
697		* invocation.
698		*
699		* <p>This method may be overridden in subclasses, but if so, must
700		* still ensure that these minimal properties hold. In particular,
701	<	* the cancel method itself must not throw exceptions.
701	>	* the {@code cancel} method itself must not throw exceptions.
702		*
703	<	* <p> This method is designed to be invoked by <em>other</em>
703	>	* <p>This method is designed to be invoked by <em>other</em>
704		* tasks. To terminate the current task, you can just return or
705		* throw an unchecked exception from its computation method, or
706	<	* invoke {@code completeExceptionally}.
706	>	* invoke {@link #completeExceptionally}.
707		*
708		* @param mayInterruptIfRunning this value is ignored in the
709		* default implementation because tasks are not in general
710	<	* cancelled via interruption.
710	>	* cancelled via interruption
711		*
712	<	* @return true if this task is now cancelled
712	>	* @return {@code true} if this task is now cancelled
713		*/
714		public boolean cancel(boolean mayInterruptIfRunning) {
715		setCompletion(CANCELLED);
#	Line 670 | Line 717 | public abstract class ForkJoinTask<V> im
717		}
718
719		/**
720	<	* Returns true if this task threw an exception or was cancelled
721	<	* @return true if this task threw an exception or was cancelled
720	>	* Returns {@code true} if this task threw an exception or was cancelled.
721	>	*
722	>	* @return {@code true} if this task threw an exception or was cancelled
723		*/
724		public final boolean isCompletedAbnormally() {
725		return (status & COMPLETION_MASK) < NORMAL;
#	Line 679 | Line 727 | public abstract class ForkJoinTask<V> im
727
728		/**
729		* Returns the exception thrown by the base computation, or a
730	<	* CancellationException if cancelled, or null if none or if the
731	<	* method has not yet completed.
732	<	* @return the exception, or null if none
730	>	* {@code CancellationException} if cancelled, or {@code null} if
731	>	* none or if the method has not yet completed.
732	>	*
733	>	* @return the exception, or {@code null} if none
734		*/
735		public final Throwable getException() {
736		int s = status & COMPLETION_MASK;
#	Line 698 | Line 747 | public abstract class ForkJoinTask<V> im
747		* {@code join} and related operations. This method may be used
748		* to induce exceptions in asynchronous tasks, or to force
749		* completion of tasks that would not otherwise complete.  Its use
750	<	* in other situations is likely to be wrong.  This method is
750	>	* in other situations is discouraged.  This method is
751		* overridable, but overridden versions must invoke {@code super}
752		* implementation to maintain guarantees.
753		*
#	Line 708 | Line 757 | public abstract class ForkJoinTask<V> im
757		*/
758		public void completeExceptionally(Throwable ex) {
759		setDoneExceptionally((ex instanceof RuntimeException) ||
760	<	(ex instanceof Error)? ex :
760	>	(ex instanceof Error) ? ex :
761		new RuntimeException(ex));
762		}
763
#	Line 718 | Line 767 | public abstract class ForkJoinTask<V> im
767		* operations. This method may be used to provide results for
768		* asynchronous tasks, or to provide alternative handling for
769		* tasks that would not otherwise complete normally. Its use in
770	<	* other situations is likely to be wrong. This method is
770	>	* other situations is discouraged. This method is
771		* overridable, but overridden versions must invoke {@code super}
772		* implementation to maintain guarantees.
773		*
774	<	* @param value the result value for this task.
774	>	* @param value the result value for this task
775		*/
776		public void complete(V value) {
777		try {
778		setRawResult(value);
779	<	} catch(Throwable rex) {
779	>	} catch (Throwable rex) {
780		setDoneExceptionally(rex);
781		return;
782		}
#	Line 743 | Line 792 | public abstract class ForkJoinTask<V> im
792
793		public final V get(long timeout, TimeUnit unit)
794		throws InterruptedException, ExecutionException, TimeoutException {
795	+	long nanos = unit.toNanos(timeout);
796		ForkJoinWorkerThread w = getWorker();
797		if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
798	<	awaitDone(w, unit.toNanos(timeout));
798	>	awaitDone(w, nanos);
799		return reportTimedFutureResult();
800		}
801
#	Line 753 | Line 803 | public abstract class ForkJoinTask<V> im
803		* Possibly executes other tasks until this task is ready, then
804		* returns the result of the computation.  This method may be more
805		* efficient than {@code join}, but is only applicable when
806	<	* there are no potemtial dependencies between continuation of the
806	>	* there are no potential dependencies between continuation of the
807		* current task and that of any other task that might be executed
808		* while helping. (This usually holds for pure divide-and-conquer
809		* tasks). This method may be invoked only from within
810	<	* ForkJoinTask computations. Attempts to invoke in other contexts
811	<	* resul!t in exceptions or errors possibly including ClassCastException.
810	>	* ForkJoinTask computations (as may be determined using method
811	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
812	>	* result in exceptions or errors, possibly including
813	>	* ClassCastException.
814	>	*
815		* @return the computed result
816		*/
817		public final V helpJoin() {
818	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
818	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
819		if (status < 0 || !w.unpushTask(this) || !tryExec())
820		reportException(busyJoin(w));
821		return getRawResult();
#	Line 771 | Line 824 | public abstract class ForkJoinTask<V> im
824		/**
825		* Possibly executes other tasks until this task is ready.  This
826		* method may be invoked only from within ForkJoinTask
827	<	* computations. Attempts to invoke in other contexts resul!t in
828	<	* exceptions or errors possibly including ClassCastException.
827	>	* computations (as may be determined using method {@link
828	>	* #inForkJoinPool}). Attempts to invoke in other contexts result
829	>	* in exceptions or errors, possibly including ClassCastException.
830		*/
831		public final void quietlyHelpJoin() {
832		if (status >= 0) {
833		ForkJoinWorkerThread w =
834	<	(ForkJoinWorkerThread)(Thread.currentThread());
834	>	(ForkJoinWorkerThread) Thread.currentThread();
835		if (!w.unpushTask(this) || !tryQuietlyInvoke())
836		busyJoin(w);
837		}
#	Line 813 | Line 867 | public abstract class ForkJoinTask<V> im
867		* Possibly executes tasks until the pool hosting the current task
868		* {@link ForkJoinPool#isQuiescent}. This method may be of use in
869		* designs in which many tasks are forked, but none are explicitly
870	<	* joined, instead executing them until all are processed.
870	>	* joined, instead executing them until all are processed.  This
871	>	* method may be invoked only from within ForkJoinTask
872	>	* computations (as may be determined using method {@link
873	>	* #inForkJoinPool}). Attempts to invoke in other contexts result
874	>	* in exceptions or errors, possibly including ClassCastException.
875		*/
876		public static void helpQuiesce() {
877	<	((ForkJoinWorkerThread)(Thread.currentThread())).
878	<	helpQuiescePool();
877	>	((ForkJoinWorkerThread) Thread.currentThread())
878	>	.helpQuiescePool();
879		}
880
881		/**
#	Line 827 | Line 885 | public abstract class ForkJoinTask<V> im
885		* never been forked, or has been forked, then completed and all
886		* outstanding joins of this task have also completed. Effects
887		* under any other usage conditions are not guaranteed, and are
888	<	* almost surely wrong. This method may be useful when executing
888	>	* discouraged. This method may be useful when executing
889		* pre-constructed trees of subtasks in loops.
890		*/
891		public void reinitialize() {
#	Line 838 | Line 896 | public abstract class ForkJoinTask<V> im
896
897		/**
898		* Returns the pool hosting the current task execution, or null
899	<	* if this task is executing outside of any pool.
900	<	* @return the pool, or null if none.
899	>	* if this task is executing outside of any ForkJoinPool.
900	>	*
901	>	* @see #inForkJoinPool
902	>	* @return the pool, or {@code null} if none
903		*/
904		public static ForkJoinPool getPool() {
905		Thread t = Thread.currentThread();
906	<	return ((t instanceof ForkJoinWorkerThread)?
907	<	((ForkJoinWorkerThread)t).pool : null);
906	>	return (t instanceof ForkJoinWorkerThread) ?
907	>	((ForkJoinWorkerThread) t).pool : null;
908	>	}
909	>
910	>	/**
911	>	* Returns {@code true} if the current thread is executing as a
912	>	* ForkJoinPool computation.
913	>	*
914	>	* @return {@code true} if the current thread is executing as a
915	>	* ForkJoinPool computation, or false otherwise
916	>	*/
917	>	public static boolean inForkJoinPool() {
918	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
919		}
920
921		/**
#	Line 854 | Line 925 | public abstract class ForkJoinTask<V> im
925		* another thread.  This method may be useful when arranging
926		* alternative local processing of tasks that could have been, but
927		* were not, stolen. This method may be invoked only from within
928	<	* ForkJoinTask computations. Attempts to invoke in other contexts
929	<	* result in exceptions or errors possibly including ClassCastException.
930	<	* @return true if unforked
928	>	* ForkJoinTask computations (as may be determined using method
929	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
930	>	* result in exceptions or errors, possibly including
931	>	* ClassCastException.
932	>	*
933	>	* @return {@code true} if unforked
934		*/
935		public boolean tryUnfork() {
936	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
936	>	return ((ForkJoinWorkerThread) Thread.currentThread())
937	>	.unpushTask(this);
938		}
939
940		/**
941		* Returns an estimate of the number of tasks that have been
942		* forked by the current worker thread but not yet executed. This
943		* value may be useful for heuristic decisions about whether to
944	<	* fork other tasks.
944	>	* fork other tasks.  This method may be invoked only from within
945	>	* ForkJoinTask computations (as may be determined using method
946	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
947	>	* result in exceptions or errors, possibly including
948	>	* ClassCastException.
949		* @return the number of tasks
950		*/
951		public static int getQueuedTaskCount() {
952	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).
953	<	getQueueSize();
952	>	return ((ForkJoinWorkerThread) Thread.currentThread())
953	>	.getQueueSize();
954		}
955
956		/**
957	<	* Returns a estimate of how many more locally queued tasks are
957	>	* Returns an estimate of how many more locally queued tasks are
958		* held by the current worker thread than there are other worker
959		* threads that might steal them.  This value may be useful for
960		* heuristic decisions about whether to fork other tasks. In many
961		* usages of ForkJoinTasks, at steady state, each worker should
962		* aim to maintain a small constant surplus (for example, 3) of
963		* tasks, and to process computations locally if this threshold is
964	<	* exceeded.
964	>	* exceeded.  This method may be invoked only from within
965	>	* ForkJoinTask computations (as may be determined using method
966	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
967	>	* result in exceptions or errors, possibly including
968	>	* ClassCastException.  *
969		* @return the surplus number of tasks, which may be negative
970		*/
971		public static int getSurplusQueuedTaskCount() {
972	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
972	>	return ((ForkJoinWorkerThread) Thread.currentThread())
973		.getEstimatedSurplusTaskCount();
974		}
975
976		// Extension methods
977
978		/**
979	<	* Returns the result that would be returned by {@code join},
980	<	* even if this task completed abnormally, or null if this task is
981	<	* not known to have been completed.  This method is designed to
982	<	* aid debugging, as well as to support extensions. Its use in any
983	<	* other context is discouraged.
979	>	* Returns the result that would be returned by {@link #join}, even
980	>	* if this task completed abnormally, or {@code null} if this task
981	>	* is not known to have been completed.  This method is designed
982	>	* to aid debugging, as well as to support extensions. Its use in
983	>	* any other context is discouraged.
984		*
985	<	* @return the result, or null if not completed.
985	>	* @return the result, or {@code null} if not completed
986		*/
987		public abstract V getRawResult();
988
#	Line 918 | Line 1001 | public abstract class ForkJoinTask<V> im
1001		* called otherwise. The return value controls whether this task
1002		* is considered to be done normally. It may return false in
1003		* asynchronous actions that require explicit invocations of
1004	<	* {@code complete} to become joinable. It may throw exceptions
1004	>	* {@link #complete} to become joinable. It may throw exceptions
1005		* to indicate abnormal exit.
1006	<	* @return true if completed normally
1006	>	*
1007	>	* @return {@code true} if completed normally
1008		* @throws Error or RuntimeException if encountered during computation
1009		*/
1010		protected abstract boolean exec();
1011
1012		/**
1013	<	* Returns, but does not unschedule or execute, the task queued by
1014	<	* the current thread but not yet executed, if one is
1013	>	* Returns, but does not unschedule or execute, a task queued by
1014	>	* the current thread but not yet executed, if one is immediately
1015		* available. There is no guarantee that this task will actually
1016	<	* be polled or executed next.  This method is designed primarily
1017	<	* to support extensions, and is unlikely to be useful otherwise.
1018	<	* This method may be invoked only from within ForkJoinTask
1019	<	* computations. Attempts to invoke in other contexts result in
1020	<	* exceptions or errors possibly including ClassCastException.
1016	>	* be polled or executed next. Conversely, this method may return
1017	>	* null even if a task exists but cannot be accessed without
1018	>	* contention with other threads.  This method is designed
1019	>	* primarily to support extensions, and is unlikely to be useful
1020	>	* otherwise.  This method may be invoked only from within
1021	>	* ForkJoinTask computations (as may be determined using method
1022	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1023	>	* result in exceptions or errors, possibly including
1024	>	* ClassCastException.
1025		*
1026	<	* @return the next task, or null if none are available
1026	>	* @return the next task, or {@code null} if none are available
1027		*/
1028		protected static ForkJoinTask<?> peekNextLocalTask() {
1029	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask();
1029	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1030	>	.peekTask();
1031		}
1032
1033		/**
#	Line 946 | Line 1035 | public abstract class ForkJoinTask<V> im
1035		* queued by the current thread but not yet executed.  This method
1036		* is designed primarily to support extensions, and is unlikely to
1037		* be useful otherwise.  This method may be invoked only from
1038	<	* within ForkJoinTask computations. Attempts to invoke in other
1039	<	* contexts result in exceptions or errors possibly including
1038	>	* within ForkJoinTask computations (as may be determined using
1039	>	* method {@link #inForkJoinPool}). Attempts to invoke in other
1040	>	* contexts result in exceptions or errors, possibly including
1041		* ClassCastException.
1042		*
1043	<	* @return the next task, or null if none are available
1043	>	* @return the next task, or {@code null} if none are available
1044		*/
1045		protected static ForkJoinTask<?> pollNextLocalTask() {
1046	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask();
1046	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1047	>	.pollLocalTask();
1048		}
1049
1050		/**
#	Line 961 | Line 1052 | public abstract class ForkJoinTask<V> im
1052		* queued by the current thread but not yet executed, if one is
1053		* available, or if not available, a task that was forked by some
1054		* other thread, if available. Availability may be transient, so a
1055	<	* {@code null} result does not necessarily imply quiecence
1055	>	* {@code null} result does not necessarily imply quiescence
1056		* of the pool this task is operating in.  This method is designed
1057		* primarily to support extensions, and is unlikely to be useful
1058		* otherwise.  This method may be invoked only from within
1059	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1060	<	* result in exceptions or errors possibly including
1059	>	* ForkJoinTask computations (as may be determined using method
1060	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1061	>	* result in exceptions or errors, possibly including
1062		* ClassCastException.
1063		*
1064	<	* @return a task, or null if none are available
1064	>	* @return a task, or {@code null} if none are available
1065		*/
1066		protected static ForkJoinTask<?> pollTask() {
1067	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).
1068	<	pollTask();
1067	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1068	>	.pollTask();
1069	>	}
1070	>
1071	>	/**
1072	>	* Adaptor for Runnables. This implements RunnableFuture
1073	>	* to be compliant with AbstractExecutorService constraints
1074	>	* when used in ForkJoinPool.
1075	>	*/
1076	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1077	>	implements RunnableFuture<T> {
1078	>	final Runnable runnable;
1079	>	final T resultOnCompletion;
1080	>	T result;
1081	>	AdaptedRunnable(Runnable runnable, T result) {
1082	>	if (runnable == null) throw new NullPointerException();
1083	>	this.runnable = runnable;
1084	>	this.resultOnCompletion = result;
1085	>	}
1086	>	public T getRawResult() { return result; }
1087	>	public void setRawResult(T v) { result = v; }
1088	>	public boolean exec() {
1089	>	runnable.run();
1090	>	result = resultOnCompletion;
1091	>	return true;
1092	>	}
1093	>	public void run() { invoke(); }
1094	>	private static final long serialVersionUID = 5232453952276885070L;
1095	>	}
1096	>
1097	>	/**
1098	>	* Adaptor for Callables
1099	>	*/
1100	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1101	>	implements RunnableFuture<T> {
1102	>	final Callable<? extends T> callable;
1103	>	T result;
1104	>	AdaptedCallable(Callable<? extends T> callable) {
1105	>	if (callable == null) throw new NullPointerException();
1106	>	this.callable = callable;
1107	>	}
1108	>	public T getRawResult() { return result; }
1109	>	public void setRawResult(T v) { result = v; }
1110	>	public boolean exec() {
1111	>	try {
1112	>	result = callable.call();
1113	>	return true;
1114	>	} catch (Error err) {
1115	>	throw err;
1116	>	} catch (RuntimeException rex) {
1117	>	throw rex;
1118	>	} catch (Exception ex) {
1119	>	throw new RuntimeException(ex);
1120	>	}
1121	>	}
1122	>	public void run() { invoke(); }
1123	>	private static final long serialVersionUID = 2838392045355241008L;
1124	>	}
1125	>
1126	>	/**
1127	>	* Returns a new ForkJoinTask that performs the {@code run}
1128	>	* method of the given Runnable as its action, and returns a null
1129	>	* result upon {@code join}.
1130	>	*
1131	>	* @param runnable the runnable action
1132	>	* @return the task
1133	>	*/
1134	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1135	>	return new AdaptedRunnable<Void>(runnable, null);
1136	>	}
1137	>
1138	>	/**
1139	>	* Returns a new ForkJoinTask that performs the {@code run}
1140	>	* method of the given Runnable as its action, and returns the
1141	>	* given result upon {@code join}.
1142	>	*
1143	>	* @param runnable the runnable action
1144	>	* @param result the result upon completion
1145	>	* @return the task
1146	>	*/
1147	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1148	>	return new AdaptedRunnable<T>(runnable, result);
1149	>	}
1150	>
1151	>	/**
1152	>	* Returns a new ForkJoinTask that performs the {@code call}
1153	>	* method of the given Callable as its action, and returns its
1154	>	* result upon {@code join}, translating any checked
1155	>	* exceptions encountered into {@code RuntimeException}.
1156	>	*
1157	>	* @param callable the callable action
1158	>	* @return the task
1159	>	*/
1160	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1161	>	return new AdaptedCallable<T>(callable);
1162		}
1163
1164		// Serialization support
#	Line 984 | Line 1169 | public abstract class ForkJoinTask<V> im
1169		* Save the state to a stream.
1170		*
1171		* @serialData the current run status and the exception thrown
1172	<	* during execution, or null if none.
1172	>	* during execution, or {@code null} if none
1173		* @param s the stream
1174		*/
1175		private void writeObject(java.io.ObjectOutputStream s)
#	Line 995 | Line 1180 | public abstract class ForkJoinTask<V> im
1180
1181		/**
1182		* Reconstitute the instance from a stream.
1183	+	*
1184		* @param s the stream
1185		*/
1186		private void readObject(java.io.ObjectInputStream s)
#	Line 1004 | Line 1190 | public abstract class ForkJoinTask<V> im
1190		status |= EXTERNAL_SIGNAL; // conservatively set external signal
1191		Object ex = s.readObject();
1192		if (ex != null)
1193	<	setDoneExceptionally((Throwable)ex);
1193	>	setDoneExceptionally((Throwable) ex);
1194		}
1195
1196	<	// Temporary Unsafe mechanics for preliminary release
1197	<	private static Unsafe getUnsafe() throws Throwable {
1196	>	// Unsafe mechanics
1197	>
1198	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1199	>	private static final long statusOffset =
1200	>	objectFieldOffset("status", ForkJoinTask.class);
1201	>
1202	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1203	>	try {
1204	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1205	>	} catch (NoSuchFieldException e) {
1206	>	// Convert Exception to corresponding Error
1207	>	NoSuchFieldError error = new NoSuchFieldError(field);
1208	>	error.initCause(e);
1209	>	throw error;
1210	>	}
1211	>	}
1212	>
1213	>	/**
1214	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1215	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1216	>	* into a jdk.
1217	>	*
1218	>	* @return a sun.misc.Unsafe
1219	>	*/
1220	>	private static sun.misc.Unsafe getUnsafe() {
1221		try {
1222	<	return Unsafe.getUnsafe();
1222	>	return sun.misc.Unsafe.getUnsafe();
1223		} catch (SecurityException se) {
1224		try {
1225		return java.security.AccessController.doPrivileged
1226	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1227	<	public Unsafe run() throws Exception {
1228	<	return getUnsafePrivileged();
1226	>	(new java.security
1227	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1228	>	public sun.misc.Unsafe run() throws Exception {
1229	>	java.lang.reflect.Field f = sun.misc
1230	>	.Unsafe.class.getDeclaredField("theUnsafe");
1231	>	f.setAccessible(true);
1232	>	return (sun.misc.Unsafe) f.get(null);
1233		}});
1234		} catch (java.security.PrivilegedActionException e) {
1235	<	throw e.getCause();
1235	>	throw new RuntimeException("Could not initialize intrinsics",
1236	>	e.getCause());
1237		}
1238		}
1239		}
1026	–
1027	–	private static Unsafe getUnsafePrivileged()
1028	–	throws NoSuchFieldException, IllegalAccessException {
1029	–	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1030	–	f.setAccessible(true);
1031	–	return (Unsafe) f.get(null);
1032	–	}
1033	–
1034	–	private static long fieldOffset(String fieldName)
1035	–	throws NoSuchFieldException {
1036	–	return _unsafe.objectFieldOffset
1037	–	(ForkJoinTask.class.getDeclaredField(fieldName));
1038	–	}
1039	–
1040	–	static final Unsafe _unsafe;
1041	–	static final long statusOffset;
1042	–
1043	–	static {
1044	–	try {
1045	–	_unsafe = getUnsafe();
1046	–	statusOffset = fieldOffset("status");
1047	–	} catch (Throwable e) {
1048	–	throw new RuntimeException("Could not initialize intrinsics", e);
1049	–	}
1050	–	}
1051	–
1240		}

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