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root/jsr166/jsr166/src/jsr166y/ForkJoinTask.java

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.37 by jsr166, Tue Aug 4 20:24:54 2009 UTC vs.
Revision 1.73 by jsr166, Sun Nov 28 21:21:03 2010 UTC

#	Line 6 | Line 6
6
7		package jsr166y;
8
9	–	import java.util.concurrent.*;
10	–
9		import java.io.Serializable;
10		import java.util.Collection;
11		import java.util.Collections;
#	Line 15 | Line 13 | import java.util.List;
13		import java.util.RandomAccess;
14		import java.util.Map;
15		import java.util.WeakHashMap;
16	+	import java.util.concurrent.Callable;
17	+	import java.util.concurrent.CancellationException;
18	+	import java.util.concurrent.ExecutionException;
19	+	import java.util.concurrent.Executor;
20	+	import java.util.concurrent.ExecutorService;
21	+	import java.util.concurrent.Future;
22	+	import java.util.concurrent.RejectedExecutionException;
23	+	import java.util.concurrent.RunnableFuture;
24	+	import java.util.concurrent.TimeUnit;
25	+	import java.util.concurrent.TimeoutException;
26
27		/**
28		* Abstract base class for tasks that run within a {@link ForkJoinPool}.
#	Line 28 | Line 36 | import java.util.WeakHashMap;
36		* start other subtasks.  As indicated by the name of this class,
37		* many programs using {@code ForkJoinTask} employ only methods
38		* {@link #fork} and {@link #join}, or derivatives such as {@link
39	<	* #invokeAll}.  However, this class also provides a number of other
40	<	* methods that can come into play in advanced usages, as well as
41	<	* extension mechanics that allow support of new forms of fork/join
42	<	* processing.
39	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
40	>	* provides a number of other methods that can come into play in
41	>	* advanced usages, as well as extension mechanics that allow
42	>	* support of new forms of fork/join processing.
43		*
44		* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
45		* The efficiency of {@code ForkJoinTask}s stems from a set of
#	Line 56 | Line 64 | import java.util.WeakHashMap;
64		* exceptions such as {@code IOExceptions} to be thrown. However,
65		* computations may still encounter unchecked exceptions, that are
66		* rethrown to callers attempting to join them. These exceptions may
67	<	* additionally include RejectedExecutionExceptions stemming from
68	<	* internal resource exhaustion such as failure to allocate internal
69	<	* task queues.
67	>	* additionally include {@link RejectedExecutionException} stemming
68	>	* from internal resource exhaustion, such as failure to allocate
69	>	* internal task queues.
70		*
71		* <p>The primary method for awaiting completion and extracting
72		* results of a task is {@link #join}, but there are several variants:
73		* The {@link Future#get} methods support interruptible and/or timed
74		* waits for completion and report results using {@code Future}
75	<	* conventions. Method {@link #helpJoin} enables callers to actively
68	<	* execute other tasks while awaiting joins, which is sometimes more
69	<	* efficient but only applies when all subtasks are known to be
70	<	* strictly tree-structured. Method {@link #invoke} is semantically
75	>	* conventions. Method {@link #invoke} is semantically
76		* equivalent to {@code fork(); join()} but always attempts to begin
77		* execution in the current thread. The "<em>quiet</em>" forms of
78		* these methods do not extract results or report exceptions. These
#	Line 80 | Line 85 | import java.util.WeakHashMap;
85		* <p>The execution status of tasks may be queried at several levels
86		* of detail: {@link #isDone} is true if a task completed in any way
87		* (including the case where a task was cancelled without executing);
83	–	* {@link #isCancelled} is true if completion was due to cancellation;
88		* {@link #isCompletedNormally} is true if a task completed without
89	<	* cancellation or encountering an exception; {@link
90	<	* #isCompletedExceptionally} is true if if the task encountered an
91	<	* exception (in which case {@link #getException} returns the
92	<	* exception); {@link #isCancelled} is true if the task was cancelled
93	<	* (in which case {@link #getException} returns a {@link
94	<	* java.util.concurrent.CancellationException}); and {@link
95	<	* #isCompletedAbnormally} is true if a task was either cancelled or
92	<	* encountered an exception.
89	>	* cancellation or encountering an exception; {@link #isCancelled} is
90	>	* true if the task was cancelled (in which case {@link #getException}
91	>	* returns a {@link java.util.concurrent.CancellationException}); and
92	>	* {@link #isCompletedAbnormally} is true if a task was either
93	>	* cancelled or encountered an exception, in which case {@link
94	>	* #getException} will return either the encountered exception or
95	>	* {@link java.util.concurrent.CancellationException}.
96		*
97		* <p>The ForkJoinTask class is not usually directly subclassed.
98		* Instead, you subclass one of the abstract classes that support a
#	Line 105 | Line 108 | import java.util.WeakHashMap;
108		* ForkJoinTasks (as may be determined using method {@link
109		* #inForkJoinPool}).  Attempts to invoke them in other contexts
110		* result in exceptions or errors, possibly including
111	<	* ClassCastException.
111	>	* {@code ClassCastException}.
112	>	*
113	>	* <p>Method {@link #join} and its variants are appropriate for use
114	>	* only when completion dependencies are acyclic; that is, the
115	>	* parallel computation can be described as a directed acyclic graph
116	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
117	>	* tasks cyclically wait for each other.  However, this framework
118	>	* supports other methods and techniques (for example the use of
119	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
120	>	* may be of use in constructing custom subclasses for problems that
121	>	* are not statically structured as DAGs.
122		*
123		* <p>Most base support methods are {@code final}, to prevent
124		* overriding of implementations that are intrinsically tied to the
#	Line 121 | Line 134 | import java.util.WeakHashMap;
134		* computation. Large tasks should be split into smaller subtasks,
135		* usually via recursive decomposition. As a very rough rule of thumb,
136		* a task should perform more than 100 and less than 10000 basic
137	<	* computational steps. If tasks are too big, then parallelism cannot
138	<	* improve throughput. If too small, then memory and internal task
139	<	* maintenance overhead may overwhelm processing.
137	>	* computational steps, and should avoid indefinite looping. If tasks
138	>	* are too big, then parallelism cannot improve throughput. If too
139	>	* small, then memory and internal task maintenance overhead may
140	>	* overwhelm processing.
141		*
142		* <p>This class provides {@code adapt} methods for {@link Runnable}
143		* and {@link Callable}, that may be of use when mixing execution of
144	<	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
145	<	* are of this form, consider using a pool in
132	<	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
144	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
145	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
146		*
147		* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
148		* used in extensions such as remote execution frameworks. It is
#	Line 141 | Line 154 | import java.util.WeakHashMap;
154		*/
155		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
156
157	<	/**
158	<	* Run control status bits packed into a single int to minimize
159	<	* footprint and to ensure atomicity (via CAS).  Status is
160	<	* initially zero, and takes on nonnegative values until
161	<	* completed, upon which status holds COMPLETED. CANCELLED, or
162	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
163	<	* blocking waits by other threads have SIGNAL_MASK bits set --
164	<	* bit 15 for external (nonFJ) waits, and the rest a count of
165	<	* waiting FJ threads.  (This representation relies on
166	<	* ForkJoinPool max thread limits). Completion of a stolen task
167	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
168	<	* though suboptimal for some purposes, we use basic builtin
169	<	* wait/notify to take advantage of "monitor inflation" in JVMs
170	<	* that we would otherwise need to emulate to avoid adding further
171	<	* per-task bookkeeping overhead. Note that bits 16-28 are
172	<	* currently unused. Also value 0x80000000 is available as spare
173	<	* completion value.
157	>	/*
158	>	* See the internal documentation of class ForkJoinPool for a
159	>	* general implementation overview.  ForkJoinTasks are mainly
160	>	* responsible for maintaining their "status" field amidst relays
161	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
162	>	* methods of this class are more-or-less layered into (1) basic
163	>	* status maintenance (2) execution and awaiting completion (3)
164	>	* user-level methods that additionally report results. This is
165	>	* sometimes hard to see because this file orders exported methods
166	>	* in a way that flows well in javadocs. In particular, most
167	>	* join mechanics are in method quietlyJoin, below.
168	>	*/
169	>
170	>	/*
171	>	* The status field holds run control status bits packed into a
172	>	* single int to minimize footprint and to ensure atomicity (via
173	>	* CAS).  Status is initially zero, and takes on nonnegative
174	>	* values until completed, upon which status holds value
175	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
176	>	* waits by other threads have the SIGNAL bit set.  Completion of
177	>	* a stolen task with SIGNAL set awakens any waiters via
178	>	* notifyAll. Even though suboptimal for some purposes, we use
179	>	* basic builtin wait/notify to take advantage of "monitor
180	>	* inflation" in JVMs that we would otherwise need to emulate to
181	>	* avoid adding further per-task bookkeeping overhead.  We want
182	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
183	>	* techniques, so use some odd coding idioms that tend to avoid
184	>	* them.
185		*/
186	+
187	+	/** The run status of this task */
188		volatile int status; // accessed directly by pool and workers
189
190	<	static final int COMPLETION_MASK      = 0xe0000000;
191	<	static final int NORMAL               = 0xe0000000; // == mask
192	<	static final int CANCELLED            = 0xc0000000;
193	<	static final int EXCEPTIONAL          = 0xa0000000;
168	<	static final int SIGNAL_MASK          = 0x0000ffff;
169	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
170	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
190	>	private static final int NORMAL      = -1;
191	>	private static final int CANCELLED   = -2;
192	>	private static final int EXCEPTIONAL = -3;
193	>	private static final int SIGNAL      =  1;
194
195		/**
196		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 181 | Line 204 | public abstract class ForkJoinTask<V> im
204		Collections.synchronizedMap
205		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
206
207	<	// within-package utilities
207	>	// Maintaining completion status
208
209		/**
210	<	* Gets current worker thread, or null if not a worker thread.
211	<	*/
189	<	static ForkJoinWorkerThread getWorker() {
190	<	Thread t = Thread.currentThread();
191	<	return ((t instanceof ForkJoinWorkerThread) ?
192	<	(ForkJoinWorkerThread) t : null);
193	<	}
194	<
195	<	final boolean casStatus(int cmp, int val) {
196	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
197	<	}
198	<
199	<	/**
200	<	* Workaround for not being able to rethrow unchecked exceptions.
201	<	*/
202	<	static void rethrowException(Throwable ex) {
203	<	if (ex != null)
204	<	UNSAFE.throwException(ex);
205	<	}
206	<
207	<	// Setting completion status
208	<
209	<	/**
210	<	* Marks completion and wakes up threads waiting to join this task.
210	>	* Marks completion and wakes up threads waiting to join this task,
211	>	* also clearing signal request bits.
212		*
213		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
214		*/
215	<	final void setCompletion(int completion) {
215	<	ForkJoinPool pool = getPool();
216	<	if (pool != null) {
217	<	int s; // Clear signal bits while setting completion status
218	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
219	<
220	<	if ((s & SIGNAL_MASK) != 0) {
221	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
222	<	pool.updateRunningCount(s);
223	<	synchronized (this) { notifyAll(); }
224	<	}
225	<	}
226	<	else
227	<	externallySetCompletion(completion);
228	<	}
229	<
230	<	/**
231	<	* Version of setCompletion for non-FJ threads.  Leaves signal
232	<	* bits for unblocked threads to adjust, and always notifies.
233	<	*/
234	<	private void externallySetCompletion(int completion) {
235	<	int s;
236	<	do {} while ((s = status) >= 0 &&
237	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
238	<	synchronized (this) { notifyAll(); }
239	<	}
240	<
241	<	/**
242	<	* Sets status to indicate normal completion.
243	<	*/
244	<	final void setNormalCompletion() {
245	<	// Try typical fast case -- single CAS, no signal, not already done.
246	<	// Manually expand casStatus to improve chances of inlining it
247	<	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
248	<	setCompletion(NORMAL);
249	<	}
250	<
251	<	// internal waiting and notification
252	<
253	<	/**
254	<	* Performs the actual monitor wait for awaitDone.
255	<	*/
256	<	private void doAwaitDone() {
257	<	// Minimize lock bias and in/de-flation effects by maximizing
258	<	// chances of waiting inside sync
259	<	try {
260	<	while (status >= 0)
261	<	synchronized (this) { if (status >= 0) wait(); }
262	<	} catch (InterruptedException ie) {
263	<	onInterruptedWait();
264	<	}
265	<	}
266	<
267	<	/**
268	<	* Performs the actual timed monitor wait for awaitDone.
269	<	*/
270	<	private void doAwaitDone(long startTime, long nanos) {
271	<	synchronized (this) {
272	<	try {
273	<	while (status >= 0) {
274	<	long nt = nanos - (System.nanoTime() - startTime);
275	<	if (nt <= 0)
276	<	break;
277	<	wait(nt / 1000000, (int) (nt % 1000000));
278	<	}
279	<	} catch (InterruptedException ie) {
280	<	onInterruptedWait();
281	<	}
282	<	}
283	<	}
284	<
285	<	// Awaiting completion
286	<
287	<	/**
288	<	* Sets status to indicate there is joiner, then waits for join,
289	<	* surrounded with pool notifications.
290	<	*
291	<	* @return status upon exit
292	<	*/
293	<	private int awaitDone(ForkJoinWorkerThread w,
294	<	boolean maintainParallelism) {
295	<	ForkJoinPool pool = (w == null) ? null : w.pool;
215	>	private void setCompletion(int completion) {
216		int s;
217		while ((s = status) >= 0) {
218	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
219	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
220	<	doAwaitDone();
301	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
302	<	adjustPoolCountsOnUnblock(pool);
218	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
219	>	if (s != 0)
220	>	synchronized (this) { notifyAll(); }
221		break;
222		}
223		}
306	–	return s;
224		}
225
226		/**
227	<	* Timed version of awaitDone
227	>	* Records exception and sets exceptional completion.
228		*
229	<	* @return status upon exit
313	<	*/
314	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
315	<	ForkJoinPool pool = (w == null) ? null : w.pool;
316	<	int s;
317	<	while ((s = status) >= 0) {
318	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
319	<	long startTime = System.nanoTime();
320	<	if (pool == null || !pool.preJoin(this, false))
321	<	doAwaitDone(startTime, nanos);
322	<	if ((s = status) >= 0) {
323	<	adjustPoolCountsOnCancelledWait(pool);
324	<	s = status;
325	<	}
326	<	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
327	<	adjustPoolCountsOnUnblock(pool);
328	<	break;
329	<	}
330	<	}
331	<	return s;
332	<	}
333	<
334	<	/**
335	<	* Notifies pool that thread is unblocked. Called by signalled
336	<	* threads when woken by non-FJ threads (which is atypical).
229	>	* @return status on exit
230		*/
231	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
339	<	int s;
340	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
341	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
342	<	pool.updateRunningCount(s);
343	<	}
344	<
345	<	/**
346	<	* Notifies pool to adjust counts on cancelled or timed out wait.
347	<	*/
348	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
349	<	if (pool != null) {
350	<	int s;
351	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
352	<	if (casStatus(s, s - 1)) {
353	<	pool.updateRunningCount(1);
354	<	break;
355	<	}
356	<	}
357	<	}
358	<	}
359	<
360	<	/**
361	<	* Handles interruptions during waits.
362	<	*/
363	<	private void onInterruptedWait() {
364	<	ForkJoinWorkerThread w = getWorker();
365	<	if (w == null)
366	<	Thread.currentThread().interrupt(); // re-interrupt
367	<	else if (w.isTerminating())
368	<	cancelIgnoringExceptions();
369	<	// else if FJworker, ignore interrupt
370	<	}
371	<
372	<	// Recording and reporting exceptions
373	<
374	<	private void setDoneExceptionally(Throwable rex) {
231	>	private void setExceptionalCompletion(Throwable rex) {
232		exceptionMap.put(this, rex);
233		setCompletion(EXCEPTIONAL);
234		}
235
236		/**
237	<	* Throws the exception associated with status s.
238	<	*
382	<	* @throws the exception
237	>	* Blocks a worker thread until completed or timed out.  Called
238	>	* only by pool.
239		*/
240	<	private void reportException(int s) {
241	<	if ((s &= COMPLETION_MASK) < NORMAL) {
242	<	if (s == CANCELLED)
243	<	throw new CancellationException();
244	<	else
245	<	rethrowException(exceptionMap.get(this));
240	>	final void internalAwaitDone(long millis, int nanos) {
241	>	int s = status;
242	>	if ((s == 0 &&
243	>	UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL)) ||
244	>	s > 0)  {
245	>	try {     // the odd construction reduces lock bias effects
246	>	synchronized (this) {
247	>	if (status > 0)
248	>	wait(millis, nanos);
249	>	else
250	>	notifyAll();
251	>	}
252	>	} catch (InterruptedException ie) {
253	>	cancelIfTerminating();
254	>	}
255		}
256		}
257
258		/**
259	<	* Returns result or throws exception using j.u.c.Future conventions.
395	<	* Only call when {@code isDone} known to be true.
259	>	* Blocks a non-worker-thread until completion.
260		*/
261	<	private V reportFutureResult()
262	<	throws InterruptedException, ExecutionException {
263	<	if (Thread.interrupted())
264	<	throw new InterruptedException();
265	<	int s = status & COMPLETION_MASK;
266	<	if (s < NORMAL) {
267	<	Throwable ex;
268	<	if (s == CANCELLED)
269	<	throw new CancellationException();
270	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
271	<	throw new ExecutionException(ex);
261	>	private void externalAwaitDone() {
262	>	if (status >= 0) {
263	>	boolean interrupted = false;
264	>	synchronized (this) {
265	>	for (;;) {
266	>	int s = status;
267	>	if (s == 0)
268	>	UNSAFE.compareAndSwapInt(this, statusOffset,
269	>	0, SIGNAL);
270	>	else if (s < 0) {
271	>	notifyAll();
272	>	break;
273	>	}
274	>	else {
275	>	try {
276	>	wait();
277	>	} catch (InterruptedException ie) {
278	>	interrupted = true;
279	>	}
280	>	}
281	>	}
282	>	}
283	>	if (interrupted)
284	>	Thread.currentThread().interrupt();
285		}
409	–	return getRawResult();
286		}
287
288		/**
289	<	* Returns result or throws exception using j.u.c.Future conventions
414	<	* with timeouts.
289	>	* Blocks a non-worker-thread until completion or interruption or timeout.
290		*/
291	<	private V reportTimedFutureResult()
292	<	throws InterruptedException, ExecutionException, TimeoutException {
291	>	private void externalInterruptibleAwaitDone(boolean timed, long nanos)
292	>	throws InterruptedException {
293		if (Thread.interrupted())
294		throw new InterruptedException();
420	–	Throwable ex;
421	–	int s = status & COMPLETION_MASK;
422	–	if (s == NORMAL)
423	–	return getRawResult();
424	–	else if (s == CANCELLED)
425	–	throw new CancellationException();
426	–	else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
427	–	throw new ExecutionException(ex);
428	–	else
429	–	throw new TimeoutException();
430	–	}
431	–
432	–	// internal execution methods
433	–
434	–	/**
435	–	* Calls exec, recording completion, and rethrowing exception if
436	–	* encountered. Caller should normally check status before calling.
437	–	*
438	–	* @return true if completed normally
439	–	*/
440	–	private boolean tryExec() {
441	–	try { // try block must contain only call to exec
442	–	if (!exec())
443	–	return false;
444	–	} catch (Throwable rex) {
445	–	setDoneExceptionally(rex);
446	–	rethrowException(rex);
447	–	return false; // not reached
448	–	}
449	–	setNormalCompletion();
450	–	return true;
451	–	}
452	–
453	–	/**
454	–	* Main execution method used by worker threads. Invokes
455	–	* base computation unless already complete.
456	–	*/
457	–	final void quietlyExec() {
295		if (status >= 0) {
296	<	try {
297	<	if (!exec())
298	<	return;
299	<	} catch (Throwable rex) {
300	<	setDoneExceptionally(rex);
301	<	return;
296	>	long startTime = timed ? System.nanoTime() : 0L;
297	>	synchronized (this) {
298	>	for (;;) {
299	>	long nt;
300	>	int s = status;
301	>	if (s == 0)
302	>	UNSAFE.compareAndSwapInt(this, statusOffset,
303	>	0, SIGNAL);
304	>	else if (s < 0) {
305	>	notifyAll();
306	>	break;
307	>	}
308	>	else if (!timed)
309	>	wait();
310	>	else if ((nt = nanos - (System.nanoTime()-startTime)) > 0L)
311	>	wait(nt / 1000000, (int)(nt % 1000000));
312	>	else
313	>	break;
314	>	}
315		}
466	–	setNormalCompletion();
316		}
317		}
318
319		/**
320	<	* Calls exec(), recording but not rethrowing exception.
321	<	* Caller should normally check status before calling.
322	<	*
474	<	* @return true if completed normally
320	>	* Unless done, calls exec and records status if completed, but
321	>	* doesn't wait for completion otherwise. Primary execution method
322	>	* for ForkJoinWorkerThread.
323		*/
324	<	private boolean tryQuietlyInvoke() {
324	>	final void quietlyExec() {
325		try {
326	<	if (!exec())
327	<	return false;
326	>	if (status < 0 || !exec())
327	>	return;
328		} catch (Throwable rex) {
329	<	setDoneExceptionally(rex);
330	<	return false;
483	<	}
484	<	setNormalCompletion();
485	<	return true;
486	<	}
487	<
488	<	/**
489	<	* Cancels, ignoring any exceptions it throws.
490	<	*/
491	<	final void cancelIgnoringExceptions() {
492	<	try {
493	<	cancel(false);
494	<	} catch (Throwable ignore) {
329	>	setExceptionalCompletion(rex);
330	>	return;
331		}
332	<	}
497	<
498	<	/**
499	<	* Main implementation of helpJoin
500	<	*/
501	<	private int busyJoin(ForkJoinWorkerThread w) {
502	<	int s;
503	<	ForkJoinTask<?> t;
504	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
505	<	t.quietlyExec();
506	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
332	>	setCompletion(NORMAL); // must be outside try block
333		}
334
335		// public methods
#	Line 512 | Line 338 | public abstract class ForkJoinTask<V> im
338		* Arranges to asynchronously execute this task.  While it is not
339		* necessarily enforced, it is a usage error to fork a task more
340		* than once unless it has completed and been reinitialized.
341	+	* Subsequent modifications to the state of this task or any data
342	+	* it operates on are not necessarily consistently observable by
343	+	* any thread other than the one executing it unless preceded by a
344	+	* call to {@link #join} or related methods, or a call to {@link
345	+	* #isDone} returning {@code true}.
346		*
347		* <p>This method may be invoked only from within {@code
348	<	* ForkJoinTask} computations (as may be determined using method
348	>	* ForkJoinPool} computations (as may be determined using method
349		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
350		* result in exceptions or errors, possibly including {@code
351		* ClassCastException}.
#	Line 528 | Line 359 | public abstract class ForkJoinTask<V> im
359		}
360
361		/**
362	<	* Returns the result of the computation when it is ready.
363	<	* This method differs from {@link #get()} in that
362	>	* Returns the result of the computation when it {@link #isDone is
363	>	* done}.  This method differs from {@link #get()} in that
364		* abnormal completion results in {@code RuntimeException} or
365	<	* {@code Error}, not {@code ExecutionException}.
365	>	* {@code Error}, not {@code ExecutionException}, and that
366	>	* interrupts of the calling thread do <em>not</em> cause the
367	>	* method to abruptly return by throwing {@code
368	>	* InterruptedException}.
369		*
370		* @return the computed result
371		*/
372		public final V join() {
373	<	ForkJoinWorkerThread w = getWorker();
374	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
375	<	reportException(awaitDone(w, true));
373	>	quietlyJoin();
374	>	Throwable ex;
375	>	if (status < NORMAL && (ex = getException()) != null)
376	>	UNSAFE.throwException(ex);
377		return getRawResult();
378		}
379
380		/**
381		* Commences performing this task, awaits its completion if
382	<	* necessary, and return its result, or throws an (unchecked)
383	<	* exception if the underlying computation did so.
382	>	* necessary, and returns its result, or throws an (unchecked)
383	>	* {@code RuntimeException} or {@code Error} if the underlying
384	>	* computation did so.
385		*
386		* @return the computed result
387		*/
388		public final V invoke() {
389	<	if (status >= 0 && tryExec())
390	<	return getRawResult();
391	<	else
392	<	return join();
389	>	quietlyInvoke();
390	>	Throwable ex;
391	>	if (status < NORMAL && (ex = getException()) != null)
392	>	UNSAFE.throwException(ex);
393	>	return getRawResult();
394		}
395
396		/**
397		* Forks the given tasks, returning when {@code isDone} holds for
398		* each task or an (unchecked) exception is encountered, in which
399	<	* case the exception is rethrown.  If more than one task
399	>	* case the exception is rethrown. If more than one task
400		* encounters an exception, then this method throws any one of
401	<	* these exceptions.  The individual status of each task may be
402	<	* checked using {@link #getException()} and related methods.
401	>	* these exceptions. If any task encounters an exception, the
402	>	* other may be cancelled. However, the execution status of
403	>	* individual tasks is not guaranteed upon exceptional return. The
404	>	* status of each task may be obtained using {@link
405	>	* #getException()} and related methods to check if they have been
406	>	* cancelled, completed normally or exceptionally, or left
407	>	* unprocessed.
408		*
409		* <p>This method may be invoked only from within {@code
410	<	* ForkJoinTask} computations (as may be determined using method
410	>	* ForkJoinPool} computations (as may be determined using method
411		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
412		* result in exceptions or errors, possibly including {@code
413		* ClassCastException}.
#	Line 583 | Line 425 | public abstract class ForkJoinTask<V> im
425		/**
426		* Forks the given tasks, returning when {@code isDone} holds for
427		* each task or an (unchecked) exception is encountered, in which
428	<	* case the exception is rethrown. If any task encounters an
429	<	* exception, others may be, but are not guaranteed to be,
430	<	* cancelled.  If more than one task encounters an exception, then
431	<	* this method throws any one of these exceptions.  The individual
432	<	* status of each task may be checked using {@link #getException()}
433	<	* and related methods.
428	>	* case the exception is rethrown. If more than one task
429	>	* encounters an exception, then this method throws any one of
430	>	* these exceptions. If any task encounters an exception, others
431	>	* may be cancelled. However, the execution status of individual
432	>	* tasks is not guaranteed upon exceptional return. The status of
433	>	* each task may be obtained using {@link #getException()} and
434	>	* related methods to check if they have been cancelled, completed
435	>	* normally or exceptionally, or left unprocessed.
436		*
437		* <p>This method may be invoked only from within {@code
438	<	* ForkJoinTask} computations (as may be determined using method
438	>	* ForkJoinPool} computations (as may be determined using method
439		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
440		* result in exceptions or errors, possibly including {@code
441		* ClassCastException}.
#	Line 612 | Line 456 | public abstract class ForkJoinTask<V> im
456		t.fork();
457		else {
458		t.quietlyInvoke();
459	<	if (ex == null)
459	>	if (ex == null && t.status < NORMAL)
460		ex = t.getException();
461		}
462		}
#	Line 623 | Line 467 | public abstract class ForkJoinTask<V> im
467		t.cancel(false);
468		else {
469		t.quietlyJoin();
470	<	if (ex == null)
470	>	if (ex == null && t.status < NORMAL)
471		ex = t.getException();
472		}
473		}
474		}
475		if (ex != null)
476	<	rethrowException(ex);
476	>	UNSAFE.throwException(ex);
477		}
478
479		/**
480		* Forks all tasks in the specified collection, returning when
481		* {@code isDone} holds for each task or an (unchecked) exception
482	<	* is encountered.  If any task encounters an exception, others
483	<	* may be, but are not guaranteed to be, cancelled.  If more than
484	<	* one task encounters an exception, then this method throws any
485	<	* one of these exceptions.  The individual status of each task
486	<	* may be checked using {@link #getException()} and related
487	<	* methods.  The behavior of this operation is undefined if the
488	<	* specified collection is modified while the operation is in
489	<	* progress.
482	>	* is encountered, in which case the exception is rethrown. If
483	>	* more than one task encounters an exception, then this method
484	>	* throws any one of these exceptions. If any task encounters an
485	>	* exception, others may be cancelled. However, the execution
486	>	* status of individual tasks is not guaranteed upon exceptional
487	>	* return. The status of each task may be obtained using {@link
488	>	* #getException()} and related methods to check if they have been
489	>	* cancelled, completed normally or exceptionally, or left
490	>	* unprocessed.
491		*
492		* <p>This method may be invoked only from within {@code
493	<	* ForkJoinTask} computations (as may be determined using method
493	>	* ForkJoinPool} computations (as may be determined using method
494		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
495		* result in exceptions or errors, possibly including {@code
496		* ClassCastException}.
#	Line 674 | Line 519 | public abstract class ForkJoinTask<V> im
519		t.fork();
520		else {
521		t.quietlyInvoke();
522	<	if (ex == null)
522	>	if (ex == null && t.status < NORMAL)
523		ex = t.getException();
524		}
525		}
#	Line 685 | Line 530 | public abstract class ForkJoinTask<V> im
530		t.cancel(false);
531		else {
532		t.quietlyJoin();
533	<	if (ex == null)
533	>	if (ex == null && t.status < NORMAL)
534		ex = t.getException();
535		}
536		}
537		}
538		if (ex != null)
539	<	rethrowException(ex);
539	>	UNSAFE.throwException(ex);
540		return tasks;
541		}
542
543		/**
544		* Attempts to cancel execution of this task. This attempt will
545	<	* fail if the task has already completed, has already been
546	<	* cancelled, or could not be cancelled for some other reason. If
547	<	* successful, and this task has not started when cancel is
548	<	* called, execution of this task is suppressed, {@link
549	<	* #isCancelled} will report true, and {@link #join} will result
550	<	* in a {@code CancellationException} being thrown.
545	>	* fail if the task has already completed or could not be
546	>	* cancelled for some other reason. If successful, and this task
547	>	* has not started when {@code cancel} is called, execution of
548	>	* this task is suppressed. After this method returns
549	>	* successfully, unless there is an intervening call to {@link
550	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
551	>	* {@link #isDone}, and {@code cancel} will return {@code true}
552	>	* and calls to {@link #join} and related methods will result in
553	>	* {@code CancellationException}.
554		*
555		* <p>This method may be overridden in subclasses, but if so, must
556	<	* still ensure that these minimal properties hold. In particular,
557	<	* the {@code cancel} method itself must not throw exceptions.
556	>	* still ensure that these properties hold. In particular, the
557	>	* {@code cancel} method itself must not throw exceptions.
558		*
559		* <p>This method is designed to be invoked by <em>other</em>
560		* tasks. To terminate the current task, you can just return or
561		* throw an unchecked exception from its computation method, or
562		* invoke {@link #completeExceptionally}.
563		*
564	<	* @param mayInterruptIfRunning this value is ignored in the
565	<	* default implementation because tasks are not
566	<	* cancelled via interruption
564	>	* @param mayInterruptIfRunning this value has no effect in the
565	>	* default implementation because interrupts are not used to
566	>	* control cancellation.
567		*
568		* @return {@code true} if this task is now cancelled
569		*/
570		public boolean cancel(boolean mayInterruptIfRunning) {
571		setCompletion(CANCELLED);
572	<	return (status & COMPLETION_MASK) == CANCELLED;
572	>	return status == CANCELLED;
573		}
574
575		/**
576	<	* Returns {@code true} if the computation performed by this task
577	<	* has completed (or has been cancelled).
578	<	*
579	<	* @return {@code true} if this computation has completed
576	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
577	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
578	>	* exceptions, but if it does anyway, we have no recourse during
579	>	* shutdown, so guard against this case.
580		*/
581	<	public final boolean isDone() {
582	<	return status < 0;
581	>	final void cancelIgnoringExceptions() {
582	>	try {
583	>	cancel(false);
584	>	} catch (Throwable ignore) {
585	>	}
586		}
587
588		/**
589	<	* Returns {@code true} if this task was cancelled.
590	<	*
740	<	* @return {@code true} if this task was cancelled
589	>	* Cancels if current thread is a terminating worker thread,
590	>	* ignoring any exceptions thrown by cancel.
591		*/
592	+	final void cancelIfTerminating() {
593	+	Thread t = Thread.currentThread();
594	+	if ((t instanceof ForkJoinWorkerThread) &&
595	+	((ForkJoinWorkerThread) t).isTerminating()) {
596	+	try {
597	+	cancel(false);
598	+	} catch (Throwable ignore) {
599	+	}
600	+	}
601	+	}
602	+
603	+	public final boolean isDone() {
604	+	return status < 0;
605	+	}
606	+
607		public final boolean isCancelled() {
608	<	return (status & COMPLETION_MASK) == CANCELLED;
608	>	return status == CANCELLED;
609		}
610
611		/**
#	Line 749 | Line 614 | public abstract class ForkJoinTask<V> im
614		* @return {@code true} if this task threw an exception or was cancelled
615		*/
616		public final boolean isCompletedAbnormally() {
617	<	return (status & COMPLETION_MASK) < NORMAL;
617	>	return status < NORMAL;
618		}
619
620		/**
#	Line 760 | Line 625 | public abstract class ForkJoinTask<V> im
625		* exception and was not cancelled
626		*/
627		public final boolean isCompletedNormally() {
628	<	return (status & COMPLETION_MASK) == NORMAL;
764	<	}
765	<
766	<	/**
767	<	* Returns {@code true} if this task threw an exception.
768	<	*
769	<	* @return {@code true} if this task threw an exception
770	<	*/
771	<	public final boolean isCompletedExceptionally() {
772	<	return (status & COMPLETION_MASK) == EXCEPTIONAL;
628	>	return status == NORMAL;
629		}
630
631		/**
#	Line 780 | Line 636 | public abstract class ForkJoinTask<V> im
636		* @return the exception, or {@code null} if none
637		*/
638		public final Throwable getException() {
639	<	int s = status & COMPLETION_MASK;
639	>	int s = status;
640		return ((s >= NORMAL)    ? null :
641		(s == CANCELLED) ? new CancellationException() :
642		exceptionMap.get(this));
#	Line 796 | Line 652 | public abstract class ForkJoinTask<V> im
652		* overridable, but overridden versions must invoke {@code super}
653		* implementation to maintain guarantees.
654		*
655	<	* @param ex the exception to throw. If this exception is
656	<	* not a RuntimeException or Error, the actual exception thrown
657	<	* will be a RuntimeException with cause ex.
655	>	* @param ex the exception to throw. If this exception is not a
656	>	* {@code RuntimeException} or {@code Error}, the actual exception
657	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
658		*/
659		public void completeExceptionally(Throwable ex) {
660	<	setDoneExceptionally((ex instanceof RuntimeException) ||
661	<	(ex instanceof Error) ? ex :
662	<	new RuntimeException(ex));
660	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
661	>	(ex instanceof Error) ? ex :
662	>	new RuntimeException(ex));
663		}
664
665		/**
666		* Completes this task, and if not already aborted or cancelled,
667	<	* returning a {@code null} result upon {@code join} and related
668	<	* operations. This method may be used to provide results for
669	<	* asynchronous tasks, or to provide alternative handling for
670	<	* tasks that would not otherwise complete normally. Its use in
671	<	* other situations is discouraged. This method is
672	<	* overridable, but overridden versions must invoke {@code super}
673	<	* implementation to maintain guarantees.
667	>	* returning the given value as the result of subsequent
668	>	* invocations of {@code join} and related operations. This method
669	>	* may be used to provide results for asynchronous tasks, or to
670	>	* provide alternative handling for tasks that would not otherwise
671	>	* complete normally. Its use in other situations is
672	>	* discouraged. This method is overridable, but overridden
673	>	* versions must invoke {@code super} implementation to maintain
674	>	* guarantees.
675		*
676		* @param value the result value for this task
677		*/
#	Line 822 | Line 679 | public abstract class ForkJoinTask<V> im
679		try {
680		setRawResult(value);
681		} catch (Throwable rex) {
682	<	setDoneExceptionally(rex);
682	>	setExceptionalCompletion(rex);
683		return;
684		}
685	<	setNormalCompletion();
829	<	}
830	<
831	<	public final V get() throws InterruptedException, ExecutionException {
832	<	ForkJoinWorkerThread w = getWorker();
833	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
834	<	awaitDone(w, true);
835	<	return reportFutureResult();
836	<	}
837	<
838	<	public final V get(long timeout, TimeUnit unit)
839	<	throws InterruptedException, ExecutionException, TimeoutException {
840	<	long nanos = unit.toNanos(timeout);
841	<	ForkJoinWorkerThread w = getWorker();
842	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
843	<	awaitDone(w, nanos);
844	<	return reportTimedFutureResult();
685	>	setCompletion(NORMAL);
686		}
687
688		/**
689	<	* Possibly executes other tasks until this task is ready, then
690	<	* returns the result of the computation.  This method may be more
850	<	* efficient than {@code join}, but is only applicable when
851	<	* there are no potential dependencies between continuation of the
852	<	* current task and that of any other task that might be executed
853	<	* while helping. (This usually holds for pure divide-and-conquer
854	<	* tasks).
855	<	*
856	<	* <p>This method may be invoked only from within {@code
857	<	* ForkJoinTask} computations (as may be determined using method
858	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
859	<	* result in exceptions or errors, possibly including {@code
860	<	* ClassCastException}.
689	>	* Waits if necessary for the computation to complete, and then
690	>	* retrieves its result.
691		*
692		* @return the computed result
693	+	* @throws CancellationException if the computation was cancelled
694	+	* @throws ExecutionException if the computation threw an
695	+	* exception
696	+	* @throws InterruptedException if the current thread is not a
697	+	* member of a ForkJoinPool and was interrupted while waiting
698		*/
699	<	public final V helpJoin() {
700	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
701	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
702	<	reportException(busyJoin(w));
699	>	public final V get() throws InterruptedException, ExecutionException {
700	>	Thread t = Thread.currentThread();
701	>	if (t instanceof ForkJoinWorkerThread)
702	>	quietlyJoin();
703	>	else
704	>	externalInterruptibleAwaitDone(false, 0L);
705	>	int s = status;
706	>	if (s != NORMAL) {
707	>	Throwable ex;
708	>	if (s == CANCELLED)
709	>	throw new CancellationException();
710	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
711	>	throw new ExecutionException(ex);
712	>	}
713		return getRawResult();
714		}
715
716		/**
717	<	* Possibly executes other tasks until this task is ready.  This
718	<	* method may be useful when processing collections of tasks when
874	<	* some have been cancelled or otherwise known to have aborted.
717	>	* Waits if necessary for at most the given time for the computation
718	>	* to complete, and then retrieves its result, if available.
719		*
720	<	* <p>This method may be invoked only from within {@code
721	<	* ForkJoinTask} computations (as may be determined using method
722	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
723	<	* result in exceptions or errors, possibly including {@code
724	<	* ClassCastException}.
720	>	* @param timeout the maximum time to wait
721	>	* @param unit the time unit of the timeout argument
722	>	* @return the computed result
723	>	* @throws CancellationException if the computation was cancelled
724	>	* @throws ExecutionException if the computation threw an
725	>	* exception
726	>	* @throws InterruptedException if the current thread is not a
727	>	* member of a ForkJoinPool and was interrupted while waiting
728	>	* @throws TimeoutException if the wait timed out
729		*/
730	<	public final void quietlyHelpJoin() {
731	<	if (status >= 0) {
732	<	ForkJoinWorkerThread w =
733	<	(ForkJoinWorkerThread) Thread.currentThread();
734	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
735	<	busyJoin(w);
730	>	public final V get(long timeout, TimeUnit unit)
731	>	throws InterruptedException, ExecutionException, TimeoutException {
732	>	long nanos = unit.toNanos(timeout);
733	>	Thread t = Thread.currentThread();
734	>	if (t instanceof ForkJoinWorkerThread)
735	>	((ForkJoinWorkerThread)t).joinTask(this, true, nanos);
736	>	else
737	>	externalInterruptibleAwaitDone(true, nanos);
738	>	int s = status;
739	>	if (s != NORMAL) {
740	>	Throwable ex;
741	>	if (s == CANCELLED)
742	>	throw new CancellationException();
743	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
744	>	throw new ExecutionException(ex);
745	>	throw new TimeoutException();
746		}
747	+	return getRawResult();
748		}
749
750		/**
751	<	* Joins this task, without returning its result or throwing an
751	>	* Joins this task, without returning its result or throwing its
752		* exception. This method may be useful when processing
753		* collections of tasks when some have been cancelled or otherwise
754		* known to have aborted.
755		*/
756		public final void quietlyJoin() {
757	<	if (status >= 0) {
758	<	ForkJoinWorkerThread w = getWorker();
759	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
760	<	awaitDone(w, true);
757	>	Thread t;
758	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
759	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
760	>	if (status >= 0) {
761	>	if (w.unpushTask(this)) {
762	>	boolean completed;
763	>	try {
764	>	completed = exec();
765	>	} catch (Throwable rex) {
766	>	setExceptionalCompletion(rex);
767	>	return;
768	>	}
769	>	if (completed) {
770	>	setCompletion(NORMAL);
771	>	return;
772	>	}
773	>	}
774	>	w.joinTask(this, false, 0L);
775	>	}
776		}
777	+	else
778	+	externalAwaitDone();
779		}
780
781		/**
782		* Commences performing this task and awaits its completion if
783	<	* necessary, without returning its result or throwing an
784	<	* exception. This method may be useful when processing
909	<	* collections of tasks when some have been cancelled or otherwise
910	<	* known to have aborted.
783	>	* necessary, without returning its result or throwing its
784	>	* exception.
785		*/
786		public final void quietlyInvoke() {
787	<	if (status >= 0 && !tryQuietlyInvoke())
788	<	quietlyJoin();
787	>	if (status >= 0) {
788	>	boolean completed;
789	>	try {
790	>	completed = exec();
791	>	} catch (Throwable rex) {
792	>	setExceptionalCompletion(rex);
793	>	return;
794	>	}
795	>	if (completed)
796	>	setCompletion(NORMAL);
797	>	else
798	>	quietlyJoin();
799	>	}
800		}
801
802		/**
#	Line 922 | Line 807 | public abstract class ForkJoinTask<V> im
807		* processed.
808		*
809		* <p>This method may be invoked only from within {@code
810	<	* ForkJoinTask} computations (as may be determined using method
810	>	* ForkJoinPool} computations (as may be determined using method
811		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
812		* result in exceptions or errors, possibly including {@code
813		* ClassCastException}.
#	Line 941 | Line 826 | public abstract class ForkJoinTask<V> im
826		* under any other usage conditions are not guaranteed.
827		* This method may be useful when executing
828		* pre-constructed trees of subtasks in loops.
829	+	*
830	+	* <p>Upon completion of this method, {@code isDone()} reports
831	+	* {@code false}, and {@code getException()} reports {@code
832	+	* null}. However, the value returned by {@code getRawResult} is
833	+	* unaffected. To clear this value, you can invoke {@code
834	+	* setRawResult(null)}.
835		*/
836		public void reinitialize() {
837	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
837	>	if (status == EXCEPTIONAL)
838		exceptionMap.remove(this);
839		status = 0;
840		}
#	Line 962 | Line 853 | public abstract class ForkJoinTask<V> im
853		}
854
855		/**
856	<	* Returns {@code true} if the current thread is executing as a
857	<	* ForkJoinPool computation.
856	>	* Returns {@code true} if the current thread is a {@link
857	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
858		*
859	<	* @return {@code true} if the current thread is executing as a
860	<	* ForkJoinPool computation, or false otherwise
859	>	* @return {@code true} if the current thread is a {@link
860	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
861	>	* or {@code false} otherwise
862		*/
863		public static boolean inForkJoinPool() {
864		return Thread.currentThread() instanceof ForkJoinWorkerThread;
#	Line 981 | Line 873 | public abstract class ForkJoinTask<V> im
873		* were not, stolen.
874		*
875		* <p>This method may be invoked only from within {@code
876	<	* ForkJoinTask} computations (as may be determined using method
876	>	* ForkJoinPool} computations (as may be determined using method
877		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
878		* result in exceptions or errors, possibly including {@code
879		* ClassCastException}.
#	Line 1000 | Line 892 | public abstract class ForkJoinTask<V> im
892		* fork other tasks.
893		*
894		* <p>This method may be invoked only from within {@code
895	<	* ForkJoinTask} computations (as may be determined using method
895	>	* ForkJoinPool} computations (as may be determined using method
896		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
897		* result in exceptions or errors, possibly including {@code
898		* ClassCastException}.
#	Line 1023 | Line 915 | public abstract class ForkJoinTask<V> im
915		* exceeded.
916		*
917		* <p>This method may be invoked only from within {@code
918	<	* ForkJoinTask} computations (as may be determined using method
918	>	* ForkJoinPool} computations (as may be determined using method
919		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
920		* result in exceptions or errors, possibly including {@code
921		* ClassCastException}.
#	Line 1081 | Line 973 | public abstract class ForkJoinTask<V> im
973		* otherwise.
974		*
975		* <p>This method may be invoked only from within {@code
976	<	* ForkJoinTask} computations (as may be determined using method
976	>	* ForkJoinPool} computations (as may be determined using method
977		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
978		* result in exceptions or errors, possibly including {@code
979		* ClassCastException}.
#	Line 1100 | Line 992 | public abstract class ForkJoinTask<V> im
992		* be useful otherwise.
993		*
994		* <p>This method may be invoked only from within {@code
995	<	* ForkJoinTask} computations (as may be determined using method
995	>	* ForkJoinPool} computations (as may be determined using method
996		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
997		* result in exceptions or errors, possibly including {@code
998		* ClassCastException}.
#	Line 1123 | Line 1015 | public abstract class ForkJoinTask<V> im
1015		* otherwise.
1016		*
1017		* <p>This method may be invoked only from within {@code
1018	<	* ForkJoinTask} computations (as may be determined using method
1018	>	* ForkJoinPool} computations (as may be determined using method
1019		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1020		* result in exceptions or errors, possibly including {@code
1021		* ClassCastException}.
#	Line 1233 | Line 1125 | public abstract class ForkJoinTask<V> im
1125		private static final long serialVersionUID = -7721805057305804111L;
1126
1127		/**
1128	<	* Save the state to a stream.
1128	>	* Saves the state to a stream (that is, serializes it).
1129		*
1130		* @serialData the current run status and the exception thrown
1131		* during execution, or {@code null} if none
#	Line 1246 | Line 1138 | public abstract class ForkJoinTask<V> im
1138		}
1139
1140		/**
1141	<	* Reconstitute the instance from a stream.
1141	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1142		*
1143		* @param s the stream
1144		*/
1145		private void readObject(java.io.ObjectInputStream s)
1146		throws java.io.IOException, ClassNotFoundException {
1147		s.defaultReadObject();
1256	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1257	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1148		Object ex = s.readObject();
1149		if (ex != null)
1150	<	setDoneExceptionally((Throwable) ex);
1150	>	setExceptionalCompletion((Throwable) ex);
1151		}
1152
1153		// Unsafe mechanics

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