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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.24 by jsr166, Mon Jul 27 21:41:53 2009 UTC vs.
Revision 1.48 by dl, Thu May 27 16:46:48 2010 UTC

#	Line 12 | Line 12 | import java.io.Serializable;
12		import java.util.Collection;
13		import java.util.Collections;
14		import java.util.List;
15	+	import java.util.RandomAccess;
16		import java.util.Map;
17		import java.util.WeakHashMap;
18
19		/**
20	<	* Abstract base class for tasks that run within a {@link
21	<	* ForkJoinPool}.  A ForkJoinTask is a thread-like entity that is much
20	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
21	>	* A {@code ForkJoinTask} is a thread-like entity that is much
22		* lighter weight than a normal thread.  Huge numbers of tasks and
23		* subtasks may be hosted by a small number of actual threads in a
24		* ForkJoinPool, at the price of some usage limitations.
25		*
26	<	* <p> A "main" ForkJoinTask begins execution when submitted to a
27	<	* {@link ForkJoinPool}. Once started, it will usually in turn start
28	<	* other subtasks.  As indicated by the name of this class, many
29	<	* programs using ForkJoinTasks employ only methods {@code fork} and
30	<	* {@code join}, or derivatives such as {@code invokeAll}.  However,
31	<	* this class also provides a number of other methods that can come
32	<	* into play in advanced usages, as well as extension mechanics that
33	<	* allow support of new forms of fork/join processing.
26	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
27	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
28	>	* start other subtasks.  As indicated by the name of this class,
29	>	* many programs using {@code ForkJoinTask} employ only methods
30	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
31	>	* #invokeAll}.  However, this class also provides a number of other
32	>	* methods that can come into play in advanced usages, as well as
33	>	* extension mechanics that allow support of new forms of fork/join
34	>	* processing.
35		*
36	<	* <p>A ForkJoinTask is a lightweight form of {@link Future}.  The
37	<	* efficiency of ForkJoinTasks stems from a set of restrictions (that
38	<	* are only partially statically enforceable) reflecting their
39	<	* intended use as computational tasks calculating pure functions or
40	<	* operating on purely isolated objects.  The primary coordination
41	<	* mechanisms are {@link #fork}, that arranges asynchronous execution,
42	<	* and {@link #join}, that doesn't proceed until the task's result has
43	<	* been computed.  Computations should avoid {@code synchronized}
44	<	* methods or blocks, and should minimize other blocking
45	<	* synchronization apart from joining other tasks or using
46	<	* synchronizers such as Phasers that are advertised to cooperate with
47	<	* fork/join scheduling. Tasks should also not perform blocking IO,
48	<	* and should ideally access variables that are completely independent
49	<	* of those accessed by other running tasks. Minor breaches of these
50	<	* restrictions, for example using shared output streams, may be
51	<	* tolerable in practice, but frequent use may result in poor
52	<	* performance, and the potential to indefinitely stall if the number
53	<	* of threads not waiting for IO or other external synchronization
54	<	* becomes exhausted. This usage restriction is in part enforced by
55	<	* not permitting checked exceptions such as {@code IOExceptions}
56	<	* to be thrown. However, computations may still encounter unchecked
57	<	* exceptions, that are rethrown to callers attempting join
58	<	* them. These exceptions may additionally include
59	<	* RejectedExecutionExceptions stemming from internal resource
60	<	* exhaustion such as failure to allocate internal task queues.
36	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
37	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
38	>	* restrictions (that are only partially statically enforceable)
39	>	* reflecting their intended use as computational tasks calculating
40	>	* pure functions or operating on purely isolated objects.  The
41	>	* primary coordination mechanisms are {@link #fork}, that arranges
42	>	* asynchronous execution, and {@link #join}, that doesn't proceed
43	>	* until the task's result has been computed.  Computations should
44	>	* avoid {@code synchronized} methods or blocks, and should minimize
45	>	* other blocking synchronization apart from joining other tasks or
46	>	* using synchronizers such as Phasers that are advertised to
47	>	* cooperate with fork/join scheduling. Tasks should also not perform
48	>	* blocking IO, and should ideally access variables that are
49	>	* completely independent of those accessed by other running
50	>	* tasks. Minor breaches of these restrictions, for example using
51	>	* shared output streams, may be tolerable in practice, but frequent
52	>	* use may result in poor performance, and the potential to
53	>	* indefinitely stall if the number of threads not waiting for IO or
54	>	* other external synchronization becomes exhausted. This usage
55	>	* restriction is in part enforced by not permitting checked
56	>	* exceptions such as {@code IOExceptions} to be thrown. However,
57	>	* computations may still encounter unchecked exceptions, that are
58	>	* rethrown to callers attempting to join them. These exceptions may
59	>	* additionally include {@link RejectedExecutionException} stemming
60	>	* from internal resource exhaustion, such as failure to allocate
61	>	* internal task queues.
62		*
63		* <p>The primary method for awaiting completion and extracting
64		* results of a task is {@link #join}, but there are several variants:
#	Line 65 | Line 68 | import java.util.WeakHashMap;
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
71	<	* equivalent to {@code fork(); join()} but always attempts to
72	<	* begin execution in the current thread. The "<em>quiet</em>" forms
73	<	* of these methods do not extract results or report exceptions. These
71	>	* equivalent to {@code fork(); join()} but always attempts to begin
72	>	* execution in the current thread. The "<em>quiet</em>" forms of
73	>	* these methods do not extract results or report exceptions. These
74		* may be useful when a set of tasks are being executed, and you need
75		* to delay processing of results or exceptions until all complete.
76		* Method {@code invokeAll} (available in multiple versions)
77		* performs the most common form of parallel invocation: forking a set
78		* of tasks and joining them all.
79		*
80	<	* <p> The ForkJoinTask class is not usually directly subclassed.
80	>	* <p>The execution status of tasks may be queried at several levels
81	>	* of detail: {@link #isDone} is true if a task completed in any way
82	>	* (including the case where a task was cancelled without executing);
83	>	* {@link #isCompletedNormally} is true if a task completed without
84	>	* cancellation or encountering an exception; {@link #isCancelled} is
85	>	* true if the task was cancelled (in which case {@link #getException}
86	>	* returns a {@link java.util.concurrent.CancellationException}); and
87	>	* {@link #isCompletedAbnormally} is true if a task was either
88	>	* cancelled or encountered an exception, in which case {@link
89	>	* #getException} will return either the encountered exception or
90	>	* {@link java.util.concurrent.CancellationException}.
91	>	*
92	>	* <p>The ForkJoinTask class is not usually directly subclassed.
93		* Instead, you subclass one of the abstract classes that support a
94	<	* particular style of fork/join processing.  Normally, a concrete
94	>	* particular style of fork/join processing, typically {@link
95	>	* RecursiveAction} for computations that do not return results, or
96	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
97		* ForkJoinTask subclass declares fields comprising its parameters,
98		* established in a constructor, and then defines a {@code compute}
99		* method that somehow uses the control methods supplied by this base
100		* class. While these methods have {@code public} access (to allow
101	<	* instances of different task subclasses to call each others
101	>	* instances of different task subclasses to call each other's
102		* methods), some of them may only be called from within other
103		* ForkJoinTasks (as may be determined using method {@link
104		* #inForkJoinPool}).  Attempts to invoke them in other contexts
105		* result in exceptions or errors, possibly including
106		* ClassCastException.
107		*
108	<	* <p>Most base support methods are {@code final} because their
109	<	* implementations are intrinsically tied to the underlying
110	<	* lightweight task scheduling framework, and so cannot be overridden.
111	<	* Developers creating new basic styles of fork/join processing should
112	<	* minimally implement {@code protected} methods
113	<	* {@link #exec}, {@link #setRawResult}, and
114	<	* {@link #getRawResult}, while also introducing an abstract
115	<	* computational method that can be implemented in its subclasses,
116	<	* possibly relying on other {@code protected} methods provided
100	<	* by this class.
108	>	* <p>Most base support methods are {@code final}, to prevent
109	>	* overriding of implementations that are intrinsically tied to the
110	>	* underlying lightweight task scheduling framework.  Developers
111	>	* creating new basic styles of fork/join processing should minimally
112	>	* implement {@code protected} methods {@link #exec}, {@link
113	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
114	>	* an abstract computational method that can be implemented in its
115	>	* subclasses, possibly relying on other {@code protected} methods
116	>	* provided by this class.
117		*
118		* <p>ForkJoinTasks should perform relatively small amounts of
119	<	* computations, otherwise splitting into smaller tasks. As a very
120	<	* rough rule of thumb, a task should perform more than 100 and less
121	<	* than 10000 basic computational steps. If tasks are too big, then
122	<	* parallelism cannot improve throughput. If too small, then memory
123	<	* and internal task maintenance overhead may overwhelm processing.
119	>	* computation. Large tasks should be split into smaller subtasks,
120	>	* usually via recursive decomposition. As a very rough rule of thumb,
121	>	* a task should perform more than 100 and less than 10000 basic
122	>	* computational steps. If tasks are too big, then parallelism cannot
123	>	* improve throughput. If too small, then memory and internal task
124	>	* maintenance overhead may overwhelm processing.
125	>	*
126	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
127	>	* and {@link Callable}, that may be of use when mixing execution of
128	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
129	>	* are of this form, consider using a pool in
130	>	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
131		*
132	<	* <p>ForkJoinTasks are {@code Serializable}, which enables them
133	<	* to be used in extensions such as remote execution frameworks. It is
134	<	* in general sensible to serialize tasks only before or after, but
135	<	* not during execution. Serialization is not relied on during
113	<	* execution itself.
132	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
133	>	* used in extensions such as remote execution frameworks. It is
134	>	* sensible to serialize tasks only before or after, but not during,
135	>	* execution. Serialization is not relied on during execution itself.
136		*
137		* @since 1.7
138		* @author Doug Lea
139		*/
140		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
141
142	+	/*
143	+	* See the internal documentation of class ForkJoinPool for a
144	+	* general implementation overview.  ForkJoinTasks are mainly
145	+	* responsible for maintaining their "status" field amidst relays
146	+	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
147	+	* methods of this class are more-or-less layered into (1) basic
148	+	* status maintenance (2) execution and awaiting completion (3)
149	+	* user-level methods that additionally report results. This is
150	+	* sometimes hard to see because this file orders exported methods
151	+	* in a way that flows well in javadocs.
152	+	*/
153	+
154		/**
155		* Run control status bits packed into a single int to minimize
156		* footprint and to ensure atomicity (via CAS).  Status is
157		* initially zero, and takes on nonnegative values until
158		* completed, upon which status holds COMPLETED. CANCELLED, or
159		* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
160	<	* blocking waits by other threads have SIGNAL_MASK bits set --
161	<	* bit 15 for external (nonFJ) waits, and the rest a count of
162	<	* waiting FJ threads.  (This representation relies on
163	<	* ForkJoinPool max thread limits). Completion of a stolen task
164	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
165	<	* though suboptimal for some purposes, we use basic builtin
166	<	* wait/notify to take advantage of "monitor inflation" in JVMs
167	<	* that we would otherwise need to emulate to avoid adding further
168	<	* per-task bookkeeping overhead. Note that bits 16-28 are
169	<	* currently unused. Also value 0x80000000 is available as spare
170	<	* completion value.
160	>	* blocking waits by other threads have the SIGNAL bit set.
161	>	*
162	>	* Completion of a stolen task with SIGNAL set awakens any waiters
163	>	* via notifyAll. Even though suboptimal for some purposes, we use
164	>	* basic builtin wait/notify to take advantage of "monitor
165	>	* inflation" in JVMs that we would otherwise need to emulate to
166	>	* avoid adding further per-task bookkeeping overhead.  We want
167	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
168	>	* techniques, so use some odd coding idioms that tend to avoid
169	>	* them.
170	>	*
171	>	* Note that bits 1-28 are currently unused. Also value
172	>	* 0x80000000 is available as spare completion value.
173		*/
174		volatile int status; // accessed directly by pool and workers
175
176	<	static final int COMPLETION_MASK      = 0xe0000000;
177	<	static final int NORMAL               = 0xe0000000; // == mask
178	<	static final int CANCELLED            = 0xc0000000;
179	<	static final int EXCEPTIONAL          = 0xa0000000;
180	<	static final int SIGNAL_MASK          = 0x0000ffff;
145	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
146	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
176	>	private static final int COMPLETION_MASK      = 0xe0000000;
177	>	private static final int NORMAL               = 0xe0000000; // == mask
178	>	private static final int CANCELLED            = 0xc0000000;
179	>	private static final int EXCEPTIONAL          = 0xa0000000;
180	>	private static final int SIGNAL               = 0x00000001;
181
182		/**
183		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 157 | Line 191 | public abstract class ForkJoinTask<V> im
191		Collections.synchronizedMap
192		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
193
194	<	// within-package utilities
161	<
162	<	/**
163	<	* Gets current worker thread, or null if not a worker thread.
164	<	*/
165	<	static ForkJoinWorkerThread getWorker() {
166	<	Thread t = Thread.currentThread();
167	<	return ((t instanceof ForkJoinWorkerThread) ?
168	<	(ForkJoinWorkerThread) t : null);
169	<	}
170	<
171	<	final boolean casStatus(int cmp, int val) {
172	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
173	<	}
174	<
175	<	/**
176	<	* Workaround for not being able to rethrow unchecked exceptions.
177	<	*/
178	<	static void rethrowException(Throwable ex) {
179	<	if (ex != null)
180	<	UNSAFE.throwException(ex);
181	<	}
182	<
183	<	// Setting completion status
194	>	// Maintaining completion status
195
196		/**
197	<	* Marks completion and wakes up threads waiting to join this task.
197	>	* Marks completion and wakes up threads waiting to join this task,
198	>	* also clearing signal request bits.
199		*
200		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
201	+	* @return status on exit
202		*/
203	<	final void setCompletion(int completion) {
191	<	ForkJoinPool pool = getPool();
192	<	if (pool != null) {
193	<	int s; // Clear signal bits while setting completion status
194	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
195	<
196	<	if ((s & SIGNAL_MASK) != 0) {
197	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
198	<	pool.updateRunningCount(s);
199	<	synchronized (this) { notifyAll(); }
200	<	}
201	<	}
202	<	else
203	<	externallySetCompletion(completion);
204	<	}
205	<
206	<	/**
207	<	* Version of setCompletion for non-FJ threads.  Leaves signal
208	<	* bits for unblocked threads to adjust, and always notifies.
209	<	*/
210	<	private void externallySetCompletion(int completion) {
203	>	private int setCompletion(int completion) {
204		int s;
205	<	do {} while ((s = status) >= 0 &&
206	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
207	<	synchronized (this) { notifyAll(); }
208	<	}
209	<
217	<	/**
218	<	* Sets status to indicate normal completion.
219	<	*/
220	<	final void setNormalCompletion() {
221	<	// Try typical fast case -- single CAS, no signal, not already done.
222	<	// Manually expand casStatus to improve chances of inlining it
223	<	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
224	<	setCompletion(NORMAL);
225	<	}
226	<
227	<	// internal waiting and notification
228	<
229	<	/**
230	<	* Performs the actual monitor wait for awaitDone.
231	<	*/
232	<	private void doAwaitDone() {
233	<	// Minimize lock bias and in/de-flation effects by maximizing
234	<	// chances of waiting inside sync
235	<	try {
236	<	while (status >= 0)
237	<	synchronized (this) { if (status >= 0) wait(); }
238	<	} catch (InterruptedException ie) {
239	<	onInterruptedWait();
240	<	}
241	<	}
242	<
243	<	/**
244	<	* Performs the actual timed monitor wait for awaitDone.
245	<	*/
246	<	private void doAwaitDone(long startTime, long nanos) {
247	<	synchronized (this) {
248	<	try {
249	<	while (status >= 0) {
250	<	long nt = nanos - System.nanoTime() - startTime;
251	<	if (nt <= 0)
252	<	break;
253	<	wait(nt / 1000000, (int) (nt % 1000000));
254	<	}
255	<	} catch (InterruptedException ie) {
256	<	onInterruptedWait();
205	>	while ((s = status) >= 0) {
206	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
207	>	if ((s & SIGNAL) != 0)
208	>	synchronized (this) { notifyAll(); }
209	>	return completion;
210		}
211		}
212	+	return s;
213		}
214
261	–	// Awaiting completion
262	–
215		/**
216	<	* Sets status to indicate there is joiner, then waits for join,
217	<	* surrounded with pool notifications.
266	<	*
267	<	* @return status upon exit
216	>	* Record exception and set exceptional completion
217	>	* @return status on exit
218		*/
219	<	private int awaitDone(ForkJoinWorkerThread w,
220	<	boolean maintainParallelism) {
221	<	ForkJoinPool pool = (w == null) ? null : w.pool;
272	<	int s;
273	<	while ((s = status) >= 0) {
274	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
275	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
276	<	doAwaitDone();
277	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
278	<	adjustPoolCountsOnUnblock(pool);
279	<	break;
280	<	}
281	<	}
282	<	return s;
219	>	private int setExceptionalCompletion(Throwable rex) {
220	>	exceptionMap.put(this, rex);
221	>	return setCompletion(EXCEPTIONAL);
222		}
223
224		/**
225	<	* Timed version of awaitDone
287	<	*
288	<	* @return status upon exit
225	>	* Blocks a worker thread until completion. Called only by pool.
226		*/
227	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
291	<	ForkJoinPool pool = (w == null) ? null : w.pool;
227	>	final void internalAwaitDone() {
228		int s;
229		while ((s = status) >= 0) {
230	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
231	<	long startTime = System.nanoTime();
232	<	if (pool == null || !pool.preJoin(this, false))
233	<	doAwaitDone(startTime, nanos);
234	<	if ((s = status) >= 0) {
235	<	adjustPoolCountsOnCancelledWait(pool);
236	<	s = status;
230	>	synchronized(this) {
231	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){
232	>	do {
233	>	try {
234	>	wait();
235	>	} catch (InterruptedException ie) {
236	>	cancelIfTerminating();
237	>	}
238	>	} while (status >= 0);
239	>	break;
240		}
302	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
303	–	adjustPoolCountsOnUnblock(pool);
304	–	break;
241		}
242		}
307	–	return s;
243		}
244
245		/**
246	<	* Notifies pool that thread is unblocked. Called by signalled
247	<	* threads when woken by non-FJ threads (which is atypical).
246	>	* Blocks a non-worker-thread until completion.
247	>	* @return status on exit
248		*/
249	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
249	>	private int externalAwaitDone() {
250		int s;
251	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
252	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
253	<	pool.updateRunningCount(s);
254	<	}
255	<
256	<	/**
257	<	* Notifies pool to adjust counts on cancelled or timed out wait.
258	<	*/
259	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
260	<	if (pool != null) {
261	<	int s;
262	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
263	<	if (casStatus(s, s - 1)) {
329	<	pool.updateRunningCount(1);
251	>	while ((s = status) >= 0) {
252	>	synchronized(this) {
253	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){
254	>	boolean interrupted = false;
255	>	do {
256	>	try {
257	>	wait();
258	>	} catch (InterruptedException ie) {
259	>	interrupted = true;
260	>	}
261	>	} while ((s = status) >= 0);
262	>	if (interrupted)
263	>	Thread.currentThread().interrupt();
264		break;
265		}
266		}
267		}
268	+	return s;
269		}
270
271		/**
272	<	* Handles interruptions during waits.
273	<	*/
339	<	private void onInterruptedWait() {
340	<	ForkJoinWorkerThread w = getWorker();
341	<	if (w == null)
342	<	Thread.currentThread().interrupt(); // re-interrupt
343	<	else if (w.isTerminating())
344	<	cancelIgnoringExceptions();
345	<	// else if FJworker, ignore interrupt
346	<	}
347	<
348	<	// Recording and reporting exceptions
349	<
350	<	private void setDoneExceptionally(Throwable rex) {
351	<	exceptionMap.put(this, rex);
352	<	setCompletion(EXCEPTIONAL);
353	<	}
354	<
355	<	/**
356	<	* Throws the exception associated with status s.
357	<	*
358	<	* @throws the exception
359	<	*/
360	<	private void reportException(int s) {
361	<	if ((s &= COMPLETION_MASK) < NORMAL) {
362	<	if (s == CANCELLED)
363	<	throw new CancellationException();
364	<	else
365	<	rethrowException(exceptionMap.get(this));
366	<	}
367	<	}
368	<
369	<	/**
370	<	* Returns result or throws exception using j.u.c.Future conventions.
371	<	* Only call when {@code isDone} known to be true.
372	<	*/
373	<	private V reportFutureResult()
374	<	throws ExecutionException, InterruptedException {
375	<	int s = status & COMPLETION_MASK;
376	<	if (s < NORMAL) {
377	<	Throwable ex;
378	<	if (s == CANCELLED)
379	<	throw new CancellationException();
380	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
381	<	throw new ExecutionException(ex);
382	<	if (Thread.interrupted())
383	<	throw new InterruptedException();
384	<	}
385	<	return getRawResult();
386	<	}
387	<
388	<	/**
389	<	* Returns result or throws exception using j.u.c.Future conventions
390	<	* with timeouts.
391	<	*/
392	<	private V reportTimedFutureResult()
393	<	throws InterruptedException, ExecutionException, TimeoutException {
394	<	Throwable ex;
395	<	int s = status & COMPLETION_MASK;
396	<	if (s == NORMAL)
397	<	return getRawResult();
398	<	if (s == CANCELLED)
399	<	throw new CancellationException();
400	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
401	<	throw new ExecutionException(ex);
402	<	if (Thread.interrupted())
403	<	throw new InterruptedException();
404	<	throw new TimeoutException();
405	<	}
406	<
407	<	// internal execution methods
408	<
409	<	/**
410	<	* Calls exec, recording completion, and rethrowing exception if
411	<	* encountered. Caller should normally check status before calling.
412	<	*
413	<	* @return true if completed normally
272	>	* Unless done, calls exec and records status if completed, but
273	>	* doesn't wait for completion otherwise.
274		*/
275	<	private boolean tryExec() {
276	<	try { // try block must contain only call to exec
277	<	if (!exec())
278	<	return false;
275	>	final void tryExec() {
276	>	try {
277	>	if (status < 0 || !exec())
278	>	return;
279		} catch (Throwable rex) {
280	<	setDoneExceptionally(rex);
281	<	rethrowException(rex);
422	<	return false; // not reached
280	>	setExceptionalCompletion(rex);
281	>	return;
282		}
283	<	setNormalCompletion();
425	<	return true;
283	>	setCompletion(NORMAL); // must be outside try block
284		}
285
286		/**
287	<	* Main execution method used by worker threads. Invokes
288	<	* base computation unless already complete.
287	>	* If not done and this task is next in worker queue, runs it,
288	>	* else waits for it.
289	>	* @return status on exit
290		*/
291	<	final void quietlyExec() {
292	<	if (status >= 0) {
293	<	try {
294	<	if (!exec())
295	<	return;
296	<	} catch (Throwable rex) {
297	<	setDoneExceptionally(rex);
298	<	return;
291	>	private int waitingJoin() {
292	>	int s = status;
293	>	if (s < 0)
294	>	return s;
295	>	Thread t = Thread.currentThread();
296	>	if (t instanceof ForkJoinWorkerThread) {
297	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
298	>	if (w.unpushTask(this)) {
299	>	boolean completed;
300	>	try {
301	>	completed = exec();
302	>	} catch (Throwable rex) {
303	>	return setExceptionalCompletion(rex);
304	>	}
305	>	if (completed)
306	>	return setCompletion(NORMAL);
307		}
308	<	setNormalCompletion();
308	>	return w.pool.awaitJoin(this);
309		}
310	+	else
311	+	return externalAwaitDone();
312		}
313
314		/**
315	<	* Calls exec(), recording but not rethrowing exception.
316	<	* Caller should normally check status before calling.
317	<	*
449	<	* @return true if completed normally
315	>	* Unless done, calls exec and records status if completed, or
316	>	* waits for completion otherwise.
317	>	* @return status on exit
318		*/
319	<	private boolean tryQuietlyInvoke() {
319	>	private int waitingInvoke() {
320	>	int s = status;
321	>	if (s < 0)
322	>	return s;
323	>	boolean completed;
324		try {
325	<	if (!exec())
454	<	return false;
325	>	completed = exec();
326		} catch (Throwable rex) {
327	<	setDoneExceptionally(rex);
457	<	return false;
327	>	return setExceptionalCompletion(rex);
328		}
329	<	setNormalCompletion();
330	<	return true;
329	>	if (completed)
330	>	return setCompletion(NORMAL);
331	>	return waitingJoin();
332		}
333
334		/**
335	<	* Cancels, ignoring any exceptions it throws.
335	>	* If this task is next in worker queue, runs it, else processes other
336	>	* tasks until complete.
337	>	* @return status on exit
338		*/
339	<	final void cancelIgnoringExceptions() {
340	<	try {
341	<	cancel(false);
342	<	} catch (Throwable ignore) {
339	>	private int busyJoin() {
340	>	int s = status;
341	>	if (s < 0)
342	>	return s;
343	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
344	>	if (w.unpushTask(this)) {
345	>	boolean completed;
346	>	try {
347	>	completed = exec();
348	>	} catch (Throwable rex) {
349	>	return setExceptionalCompletion(rex);
350	>	}
351	>	if (completed)
352	>	return setCompletion(NORMAL);
353		}
354	+	return w.execWhileJoining(this);
355		}
356
357		/**
358	<	* Main implementation of helpJoin
358	>	* Returns result or throws exception associated with given status.
359	>	* @param s the status
360		*/
361	<	private int busyJoin(ForkJoinWorkerThread w) {
362	<	int s;
363	<	ForkJoinTask<?> t;
364	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
365	<	t.quietlyExec();
481	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
361	>	private V reportResult(int s) {
362	>	Throwable ex;
363	>	if (s < NORMAL && (ex = getException()) != null)
364	>	UNSAFE.throwException(ex);
365	>	return getRawResult();
366		}
367
368		// public methods
#	Line 486 | Line 370 | public abstract class ForkJoinTask<V> im
370		/**
371		* Arranges to asynchronously execute this task.  While it is not
372		* necessarily enforced, it is a usage error to fork a task more
373	<	* than once unless it has completed and been reinitialized.  This
374	<	* method may be invoked only from within ForkJoinTask
375	<	* computations (as may be determined using method {@link
376	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
377	<	* in exceptions or errors, possibly including ClassCastException.
373	>	* than once unless it has completed and been reinitialized.
374	>	* Subsequent modifications to the state of this task or any data
375	>	* it operates on are not necessarily consistently observable by
376	>	* any thread other than the one executing it unless preceded by a
377	>	* call to {@link #join} or related methods, or a call to {@link
378	>	* #isDone} returning {@code true}.
379	>	*
380	>	* <p>This method may be invoked only from within {@code
381	>	* ForkJoinTask} computations (as may be determined using method
382	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
383	>	* result in exceptions or errors, possibly including {@code
384	>	* ClassCastException}.
385		*
386	<	* @return {@code this}, to simplify usage.
386	>	* @return {@code this}, to simplify usage
387		*/
388		public final ForkJoinTask<V> fork() {
389		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 501 | Line 392 | public abstract class ForkJoinTask<V> im
392		}
393
394		/**
395	<	* Returns the result of the computation when it is ready.
396	<	* This method differs from {@code get} in that abnormal
397	<	* completion results in RuntimeExceptions or Errors, not
398	<	* ExecutionExceptions.
395	>	* Returns the result of the computation when it {@link #isDone is done}.
396	>	* This method differs from {@link #get()} in that
397	>	* abnormal completion results in {@code RuntimeException} or
398	>	* {@code Error}, not {@code ExecutionException}.
399		*
400		* @return the computed result
401		*/
402		public final V join() {
403	<	ForkJoinWorkerThread w = getWorker();
513	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
514	<	reportException(awaitDone(w, true));
515	<	return getRawResult();
403	>	return reportResult(waitingJoin());
404		}
405
406		/**
407		* Commences performing this task, awaits its completion if
408	<	* necessary, and return its result.
408	>	* necessary, and return its result, or throws an (unchecked)
409	>	* exception if the underlying computation did so.
410		*
522	–	* @throws Throwable (a RuntimeException, Error, or unchecked
523	–	* exception) if the underlying computation did so
411		* @return the computed result
412		*/
413		public final V invoke() {
414	<	if (status >= 0 && tryExec())
528	<	return getRawResult();
529	<	else
530	<	return join();
414	>	return reportResult(waitingInvoke());
415		}
416
417		/**
418	<	* Forks both tasks, returning when {@code isDone} holds for
419	<	* both of them or an exception is encountered. This method may be
420	<	* invoked only from within ForkJoinTask computations (as may be
421	<	* determined using method {@link #inForkJoinPool}). Attempts to
422	<	* invoke in other contexts result in exceptions or errors,
423	<	* possibly including ClassCastException.
418	>	* Forks the given tasks, returning when {@code isDone} holds for
419	>	* each task or an (unchecked) exception is encountered, in which
420	>	* case the exception is rethrown.  If either task encounters an
421	>	* exception, the other one may be, but is not guaranteed to be,
422	>	* cancelled.  If both tasks throw an exception, then this method
423	>	* throws one of them.  The individual status of each task may be
424	>	* checked using {@link #getException()} and related methods.
425		*
426	<	* @param t1 one task
427	<	* @param t2 the other task
428	<	* @throws NullPointerException if t1 or t2 are null
429	<	* @throws RuntimeException or Error if either task did so
426	>	* <p>This method may be invoked only from within {@code
427	>	* ForkJoinTask} computations (as may be determined using method
428	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
429	>	* result in exceptions or errors, possibly including {@code
430	>	* ClassCastException}.
431	>	*
432	>	* @param t1 the first task
433	>	* @param t2 the second task
434	>	* @throws NullPointerException if any task is null
435		*/
436	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
436	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
437		t2.fork();
438		t1.invoke();
439		t2.join();
440		}
441
442		/**
443	<	* Forks the given tasks, returning when {@code isDone} holds
444	<	* for all of them. If any task encounters an exception, others
445	<	* may be cancelled.  This method may be invoked only from within
446	<	* ForkJoinTask computations (as may be determined using method
447	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
448	<	* result in exceptions or errors, possibly including
449	<	* ClassCastException.
443	>	* Forks the given tasks, returning when {@code isDone} holds for
444	>	* each task or an (unchecked) exception is encountered, in which
445	>	* case the exception is rethrown. If any task encounters an
446	>	* exception, others may be, but are not guaranteed to be,
447	>	* cancelled.  If more than one task encounters an exception, then
448	>	* this method throws any one of these exceptions.  The individual
449	>	* status of each task may be checked using {@link #getException()}
450	>	* and related methods.
451	>	*
452	>	* <p>This method may be invoked only from within {@code
453	>	* ForkJoinTask} computations (as may be determined using method
454	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
455	>	* result in exceptions or errors, possibly including {@code
456	>	* ClassCastException}.
457		*
458	<	* @param tasks the array of tasks
459	<	* @throws NullPointerException if tasks or any element are null
563	<	* @throws RuntimeException or Error if any task did so
458	>	* @param tasks the tasks
459	>	* @throws NullPointerException if any task is null
460		*/
461		public static void invokeAll(ForkJoinTask<?>... tasks) {
462		Throwable ex = null;
#	Line 573 | Line 469 | public abstract class ForkJoinTask<V> im
469		}
470		else if (i != 0)
471		t.fork();
472	<	else {
473	<	t.quietlyInvoke();
578	<	if (ex == null)
579	<	ex = t.getException();
580	<	}
472	>	else if (t.waitingInvoke() < NORMAL && ex == null)
473	>	ex = t.getException();
474		}
475		for (int i = 1; i <= last; ++i) {
476		ForkJoinTask<?> t = tasks[i];
477		if (t != null) {
478		if (ex != null)
479		t.cancel(false);
480	<	else {
481	<	t.quietlyJoin();
589	<	if (ex == null)
590	<	ex = t.getException();
591	<	}
480	>	else if (t.waitingJoin() < NORMAL && ex == null)
481	>	ex = t.getException();
482		}
483		}
484		if (ex != null)
485	<	rethrowException(ex);
485	>	UNSAFE.throwException(ex);
486		}
487
488		/**
489	<	* Forks all tasks in the collection, returning when
490	<	* {@code isDone} holds for all of them. If any task
491	<	* encounters an exception, others may be cancelled.  This method
492	<	* may be invoked only from within ForkJoinTask computations (as
493	<	* may be determined using method {@link
494	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
495	<	* in exceptions or errors, possibly including ClassCastException.
489	>	* Forks all tasks in the specified collection, returning when
490	>	* {@code isDone} holds for each task or an (unchecked) exception
491	>	* is encountered.  If any task encounters an exception, others
492	>	* may be, but are not guaranteed to be, cancelled.  If more than
493	>	* one task encounters an exception, then this method throws any
494	>	* one of these exceptions.  The individual status of each task
495	>	* may be checked using {@link #getException()} and related
496	>	* methods.  The behavior of this operation is undefined if the
497	>	* specified collection is modified while the operation is in
498	>	* progress.
499	>	*
500	>	* <p>This method may be invoked only from within {@code
501	>	* ForkJoinTask} computations (as may be determined using method
502	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
503	>	* result in exceptions or errors, possibly including {@code
504	>	* ClassCastException}.
505		*
506		* @param tasks the collection of tasks
507		* @return the tasks argument, to simplify usage
508		* @throws NullPointerException if tasks or any element are null
610	–	* @throws RuntimeException or Error if any task did so
509		*/
510		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
511	<	if (!(tasks instanceof List<?>)) {
511	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
512		invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
513		return tasks;
514		}
#	Line 627 | Line 525 | public abstract class ForkJoinTask<V> im
525		}
526		else if (i != 0)
527		t.fork();
528	<	else {
529	<	t.quietlyInvoke();
632	<	if (ex == null)
633	<	ex = t.getException();
634	<	}
528	>	else if (t.waitingInvoke() < NORMAL && ex == null)
529	>	ex = t.getException();
530		}
531		for (int i = 1; i <= last; ++i) {
532		ForkJoinTask<?> t = ts.get(i);
533		if (t != null) {
534		if (ex != null)
535		t.cancel(false);
536	<	else {
537	<	t.quietlyJoin();
643	<	if (ex == null)
644	<	ex = t.getException();
645	<	}
536	>	else if (t.waitingJoin() < NORMAL && ex == null)
537	>	ex = t.getException();
538		}
539		}
540		if (ex != null)
541	<	rethrowException(ex);
541	>	UNSAFE.throwException(ex);
542		return tasks;
543		}
544
545		/**
546	<	* Returns {@code true} if the computation performed by this task
547	<	* has completed (or has been cancelled).
548	<	*
549	<	* @return {@code true} if this computation has completed
550	<	*/
551	<	public final boolean isDone() {
552	<	return status < 0;
661	<	}
662	<
663	<	/**
664	<	* Returns {@code true} if this task was cancelled.
665	<	*
666	<	* @return {@code true} if this task was cancelled
667	<	*/
668	<	public final boolean isCancelled() {
669	<	return (status & COMPLETION_MASK) == CANCELLED;
670	<	}
671	<
672	<	/**
673	<	* Asserts that the results of this task's computation will not be
674	<	* used. If a cancellation occurs before attempting to execute this
675	<	* task, execution will be suppressed, {@link #isCancelled}
676	<	* will report true, and {@link #join} will result in a
677	<	* {@code CancellationException} being thrown. Otherwise, when
678	<	* cancellation races with completion, there are no guarantees
679	<	* about whether {@code isCancelled} will report {@code true},
680	<	* whether {@code join} will return normally or via an exception,
681	<	* or whether these behaviors will remain consistent upon repeated
682	<	* invocation.
546	>	* Attempts to cancel execution of this task. This attempt will
547	>	* fail if the task has already completed, has already been
548	>	* cancelled, or could not be cancelled for some other reason. If
549	>	* successful, and this task has not started when cancel is
550	>	* called, execution of this task is suppressed, {@link
551	>	* #isCancelled} will report true, and {@link #join} will result
552	>	* in a {@code CancellationException} being thrown.
553		*
554		* <p>This method may be overridden in subclasses, but if so, must
555		* still ensure that these minimal properties hold. In particular,
556	<	* the cancel method itself must not throw exceptions.
556	>	* the {@code cancel} method itself must not throw exceptions.
557		*
558	<	* <p> This method is designed to be invoked by <em>other</em>
558	>	* <p>This method is designed to be invoked by <em>other</em>
559		* tasks. To terminate the current task, you can just return or
560		* throw an unchecked exception from its computation method, or
561		* invoke {@link #completeExceptionally}.
562		*
563		* @param mayInterruptIfRunning this value is ignored in the
564	<	* default implementation because tasks are not in general
564	>	* default implementation because tasks are not
565		* cancelled via interruption
566		*
567		* @return {@code true} if this task is now cancelled
#	Line 702 | Line 572 | public abstract class ForkJoinTask<V> im
572		}
573
574		/**
575	+	* Cancels, ignoring any exceptions it throws. Used during worker
576	+	* and pool shutdown.
577	+	*/
578	+	final void cancelIgnoringExceptions() {
579	+	try {
580	+	cancel(false);
581	+	} catch (Throwable ignore) {
582	+	}
583	+	}
584	+
585	+	/**
586	+	* Cancels ignoring exceptions if worker is terminating
587	+	*/
588	+	private void cancelIfTerminating() {
589	+	Thread t = Thread.currentThread();
590	+	if ((t instanceof ForkJoinWorkerThread) &&
591	+	((ForkJoinWorkerThread) t).isTerminating()) {
592	+	try {
593	+	cancel(false);
594	+	} catch (Throwable ignore) {
595	+	}
596	+	}
597	+	}
598	+
599	+	public final boolean isDone() {
600	+	return status < 0;
601	+	}
602	+
603	+	public final boolean isCancelled() {
604	+	return (status & COMPLETION_MASK) == CANCELLED;
605	+	}
606	+
607	+	/**
608		* Returns {@code true} if this task threw an exception or was cancelled.
609		*
610		* @return {@code true} if this task threw an exception or was cancelled
#	Line 711 | Line 614 | public abstract class ForkJoinTask<V> im
614		}
615
616		/**
617	+	* Returns {@code true} if this task completed without throwing an
618	+	* exception and was not cancelled.
619	+	*
620	+	* @return {@code true} if this task completed without throwing an
621	+	* exception and was not cancelled
622	+	*/
623	+	public final boolean isCompletedNormally() {
624	+	return (status & COMPLETION_MASK) == NORMAL;
625	+	}
626	+
627	+	/**
628		* Returns the exception thrown by the base computation, or a
629	<	* CancellationException if cancelled, or null if none or if the
630	<	* method has not yet completed.
629	>	* {@code CancellationException} if cancelled, or {@code null} if
630	>	* none or if the method has not yet completed.
631		*
632		* @return the exception, or {@code null} if none
633		*/
634		public final Throwable getException() {
635		int s = status & COMPLETION_MASK;
636	<	if (s >= NORMAL)
637	<	return null;
638	<	if (s == CANCELLED)
725	<	return new CancellationException();
726	<	return exceptionMap.get(this);
636	>	return ((s >= NORMAL)    ? null :
637	>	(s == CANCELLED) ? new CancellationException() :
638	>	exceptionMap.get(this));
639		}
640
641		/**
#	Line 732 | Line 644 | public abstract class ForkJoinTask<V> im
644		* {@code join} and related operations. This method may be used
645		* to induce exceptions in asynchronous tasks, or to force
646		* completion of tasks that would not otherwise complete.  Its use
647	<	* in other situations is likely to be wrong.  This method is
647	>	* in other situations is discouraged.  This method is
648		* overridable, but overridden versions must invoke {@code super}
649		* implementation to maintain guarantees.
650		*
651	<	* @param ex the exception to throw. If this exception is
652	<	* not a RuntimeException or Error, the actual exception thrown
653	<	* will be a RuntimeException with cause ex.
651	>	* @param ex the exception to throw. If this exception is not a
652	>	* {@code RuntimeException} or {@code Error}, the actual exception
653	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
654		*/
655		public void completeExceptionally(Throwable ex) {
656	<	setDoneExceptionally((ex instanceof RuntimeException) ||
657	<	(ex instanceof Error) ? ex :
658	<	new RuntimeException(ex));
656	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
657	>	(ex instanceof Error) ? ex :
658	>	new RuntimeException(ex));
659		}
660
661		/**
#	Line 752 | Line 664 | public abstract class ForkJoinTask<V> im
664		* operations. This method may be used to provide results for
665		* asynchronous tasks, or to provide alternative handling for
666		* tasks that would not otherwise complete normally. Its use in
667	<	* other situations is likely to be wrong. This method is
667	>	* other situations is discouraged. This method is
668		* overridable, but overridden versions must invoke {@code super}
669		* implementation to maintain guarantees.
670		*
#	Line 762 | Line 674 | public abstract class ForkJoinTask<V> im
674		try {
675		setRawResult(value);
676		} catch (Throwable rex) {
677	<	setDoneExceptionally(rex);
677	>	setExceptionalCompletion(rex);
678		return;
679		}
680	<	setNormalCompletion();
680	>	setCompletion(NORMAL);
681		}
682
683		public final V get() throws InterruptedException, ExecutionException {
684	<	ForkJoinWorkerThread w = getWorker();
685	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
686	<	awaitDone(w, true);
687	<	return reportFutureResult();
684	>	int s = waitingJoin() & COMPLETION_MASK;
685	>	if (Thread.interrupted())
686	>	throw new InterruptedException();
687	>	if (s < NORMAL) {
688	>	Throwable ex;
689	>	if (s == CANCELLED)
690	>	throw new CancellationException();
691	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
692	>	throw new ExecutionException(ex);
693	>	}
694	>	return getRawResult();
695		}
696
697		public final V get(long timeout, TimeUnit unit)
698		throws InterruptedException, ExecutionException, TimeoutException {
699	<	ForkJoinWorkerThread w = getWorker();
700	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
701	<	awaitDone(w, unit.toNanos(timeout));
702	<	return reportTimedFutureResult();
699	>	Thread t = Thread.currentThread();
700	>	ForkJoinPool pool;
701	>	if (t instanceof ForkJoinWorkerThread) {
702	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
703	>	if (status >= 0 && w.unpushTask(this))
704	>	tryExec();
705	>	pool = w.pool;
706	>	}
707	>	else
708	>	pool = null;
709	>	/*
710	>	* Timed wait loop intermixes cases for fj (pool != null) and
711	>	* non FJ threads. For FJ, decrement pool count but don't try
712	>	* for replacement; increment count on completion. For non-FJ,
713	>	* deal with interrupts. This is messy, but a little less so
714	>	* than is splitting the FJ and nonFJ cases.
715	>	*/
716	>	boolean interrupted = false;
717	>	boolean dec = false; // true if pool count decremented
718	>	for (;;) {
719	>	if (Thread.interrupted() && pool == null) {
720	>	interrupted = true;
721	>	break;
722	>	}
723	>	int s = status;
724	>	if (s < 0)
725	>	break;
726	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
727	>	s, s | SIGNAL)) {
728	>	long startTime = System.nanoTime();
729	>	long nanos = unit.toNanos(timeout);
730	>	long nt; // wait time
731	>	while (status >= 0 &&
732	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
733	>	if (pool != null && !dec)
734	>	dec = pool.tryDecrementRunningCount();
735	>	else {
736	>	long ms = nt / 1000000;
737	>	int ns = (int) (nt % 1000000);
738	>	try {
739	>	synchronized(this) {
740	>	if (status >= 0)
741	>	wait(ms, ns);
742	>	}
743	>	} catch (InterruptedException ie) {
744	>	if (pool != null)
745	>	cancelIfTerminating();
746	>	else {
747	>	interrupted = true;
748	>	break;
749	>	}
750	>	}
751	>	}
752	>	}
753	>	break;
754	>	}
755	>	}
756	>	if (pool != null && dec)
757	>	pool.updateRunningCount(1);
758	>	if (interrupted)
759	>	throw new InterruptedException();
760	>	int es = status & COMPLETION_MASK;
761	>	if (es != NORMAL) {
762	>	Throwable ex;
763	>	if (es == CANCELLED)
764	>	throw new CancellationException();
765	>	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
766	>	throw new ExecutionException(ex);
767	>	throw new TimeoutException();
768	>	}
769	>	return getRawResult();
770		}
771
772		/**
773	<	* Possibly executes other tasks until this task is ready, then
774	<	* returns the result of the computation.  This method may be more
775	<	* efficient than {@code join}, but is only applicable when
776	<	* there are no potential dependencies between continuation of the
777	<	* current task and that of any other task that might be executed
778	<	* while helping. (This usually holds for pure divide-and-conquer
779	<	* tasks). This method may be invoked only from within
780	<	* ForkJoinTask computations (as may be determined using method
781	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
782	<	* result in exceptions or errors, possibly including
783	<	* ClassCastException.
773	>	* Possibly executes other tasks until this task {@link #isDone is
774	>	* done}, then returns the result of the computation.  This method
775	>	* may be more efficient than {@code join}, but is only applicable
776	>	* when there are no potential dependencies between continuation
777	>	* of the current task and that of any other task that might be
778	>	* executed while helping. (This usually holds for pure
779	>	* divide-and-conquer tasks).
780	>	*
781	>	* <p>This method may be invoked only from within {@code
782	>	* ForkJoinTask} computations (as may be determined using method
783	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
784	>	* result in exceptions or errors, possibly including {@code
785	>	* ClassCastException}.
786		*
787		* @return the computed result
788		*/
789		public final V helpJoin() {
790	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
803	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
804	<	reportException(busyJoin(w));
805	<	return getRawResult();
790	>	return reportResult(busyJoin());
791		}
792
793		/**
794	<	* Possibly executes other tasks until this task is ready.  This
795	<	* method may be invoked only from within ForkJoinTask
796	<	* computations (as may be determined using method {@link
797	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
798	<	* in exceptions or errors, possibly including ClassCastException.
794	>	* Possibly executes other tasks until this task {@link #isDone is
795	>	* done}.  This method may be useful when processing collections
796	>	* of tasks when some have been cancelled or otherwise known to
797	>	* have aborted.
798	>	*
799	>	* <p>This method may be invoked only from within {@code
800	>	* ForkJoinTask} computations (as may be determined using method
801	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
802	>	* result in exceptions or errors, possibly including {@code
803	>	* ClassCastException}.
804		*/
805		public final void quietlyHelpJoin() {
806	<	if (status >= 0) {
817	<	ForkJoinWorkerThread w =
818	<	(ForkJoinWorkerThread) Thread.currentThread();
819	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
820	<	busyJoin(w);
821	<	}
806	>	busyJoin();
807		}
808
809		/**
#	Line 828 | Line 813 | public abstract class ForkJoinTask<V> im
813		* known to have aborted.
814		*/
815		public final void quietlyJoin() {
816	<	if (status >= 0) {
832	<	ForkJoinWorkerThread w = getWorker();
833	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
834	<	awaitDone(w, true);
835	<	}
816	>	waitingJoin();
817		}
818
819		/**
#	Line 843 | Line 824 | public abstract class ForkJoinTask<V> im
824		* known to have aborted.
825		*/
826		public final void quietlyInvoke() {
827	<	if (status >= 0 && !tryQuietlyInvoke())
847	<	quietlyJoin();
827	>	waitingInvoke();
828		}
829
830		/**
831		* Possibly executes tasks until the pool hosting the current task
832	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
833	<	* designs in which many tasks are forked, but none are explicitly
834	<	* joined, instead executing them until all are processed.
832	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
833	>	* be of use in designs in which many tasks are forked, but none
834	>	* are explicitly joined, instead executing them until all are
835	>	* processed.
836	>	*
837	>	* <p>This method may be invoked only from within {@code
838	>	* ForkJoinTask} computations (as may be determined using method
839	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
840	>	* result in exceptions or errors, possibly including {@code
841	>	* ClassCastException}.
842		*/
843		public static void helpQuiesce() {
844		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 864 | Line 851 | public abstract class ForkJoinTask<V> im
851		* this task, but only if reuse occurs when this task has either
852		* never been forked, or has been forked, then completed and all
853		* outstanding joins of this task have also completed. Effects
854	<	* under any other usage conditions are not guaranteed, and are
855	<	* almost surely wrong. This method may be useful when executing
854	>	* under any other usage conditions are not guaranteed.
855	>	* This method may be useful when executing
856		* pre-constructed trees of subtasks in loops.
857		*/
858		public void reinitialize() {
#	Line 878 | Line 865 | public abstract class ForkJoinTask<V> im
865		* Returns the pool hosting the current task execution, or null
866		* if this task is executing outside of any ForkJoinPool.
867		*
868	+	* @see #inForkJoinPool
869		* @return the pool, or {@code null} if none
870		*/
871		public static ForkJoinPool getPool() {
#	Line 903 | Line 891 | public abstract class ForkJoinTask<V> im
891		* by the current thread, and has not commenced executing in
892		* another thread.  This method may be useful when arranging
893		* alternative local processing of tasks that could have been, but
894	<	* were not, stolen. This method may be invoked only from within
895	<	* ForkJoinTask computations (as may be determined using method
896	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
897	<	* result in exceptions or errors, possibly including
898	<	* ClassCastException.
894	>	* were not, stolen.
895	>	*
896	>	* <p>This method may be invoked only from within {@code
897	>	* ForkJoinTask} computations (as may be determined using method
898	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
899	>	* result in exceptions or errors, possibly including {@code
900	>	* ClassCastException}.
901		*
902		* @return {@code true} if unforked
903		*/
#	Line 922 | Line 912 | public abstract class ForkJoinTask<V> im
912		* value may be useful for heuristic decisions about whether to
913		* fork other tasks.
914		*
915	+	* <p>This method may be invoked only from within {@code
916	+	* ForkJoinTask} computations (as may be determined using method
917	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
918	+	* result in exceptions or errors, possibly including {@code
919	+	* ClassCastException}.
920	+	*
921		* @return the number of tasks
922		*/
923		public static int getQueuedTaskCount() {
#	Line 939 | Line 935 | public abstract class ForkJoinTask<V> im
935		* tasks, and to process computations locally if this threshold is
936		* exceeded.
937		*
938	+	* <p>This method may be invoked only from within {@code
939	+	* ForkJoinTask} computations (as may be determined using method
940	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
941	+	* result in exceptions or errors, possibly including {@code
942	+	* ClassCastException}.
943	+	*
944		* @return the surplus number of tasks, which may be negative
945		*/
946		public static int getSurplusQueuedTaskCount() {
#	Line 974 | Line 976 | public abstract class ForkJoinTask<V> im
976		* called otherwise. The return value controls whether this task
977		* is considered to be done normally. It may return false in
978		* asynchronous actions that require explicit invocations of
979	<	* {@link #complete} to become joinable. It may throw exceptions
980	<	* to indicate abnormal exit.
979	>	* {@link #complete} to become joinable. It may also throw an
980	>	* (unchecked) exception to indicate abnormal exit.
981		*
982		* @return {@code true} if completed normally
981	–	* @throws Error or RuntimeException if encountered during computation
983		*/
984		protected abstract boolean exec();
985
986		/**
987	<	* Returns, but does not unschedule or execute, the task queued by
988	<	* the current thread but not yet executed, if one is
987	>	* Returns, but does not unschedule or execute, a task queued by
988	>	* the current thread but not yet executed, if one is immediately
989		* available. There is no guarantee that this task will actually
990	<	* be polled or executed next.  This method is designed primarily
991	<	* to support extensions, and is unlikely to be useful otherwise.
992	<	* This method may be invoked only from within ForkJoinTask
993	<	* computations (as may be determined using method {@link
994	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
995	<	* in exceptions or errors, possibly including ClassCastException.
990	>	* be polled or executed next. Conversely, this method may return
991	>	* null even if a task exists but cannot be accessed without
992	>	* contention with other threads.  This method is designed
993	>	* primarily to support extensions, and is unlikely to be useful
994	>	* otherwise.
995	>	*
996	>	* <p>This method may be invoked only from within {@code
997	>	* ForkJoinTask} computations (as may be determined using method
998	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
999	>	* result in exceptions or errors, possibly including {@code
1000	>	* ClassCastException}.
1001		*
1002		* @return the next task, or {@code null} if none are available
1003		*/
#	Line 1004 | Line 1010 | public abstract class ForkJoinTask<V> im
1010		* Unschedules and returns, without executing, the next task
1011		* queued by the current thread but not yet executed.  This method
1012		* is designed primarily to support extensions, and is unlikely to
1013	<	* be useful otherwise.  This method may be invoked only from
1014	<	* within ForkJoinTask computations (as may be determined using
1015	<	* method {@link #inForkJoinPool}). Attempts to invoke in other
1016	<	* contexts result in exceptions or errors, possibly including
1017	<	* ClassCastException.
1013	>	* be useful otherwise.
1014	>	*
1015	>	* <p>This method may be invoked only from within {@code
1016	>	* ForkJoinTask} computations (as may be determined using method
1017	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1018	>	* result in exceptions or errors, possibly including {@code
1019	>	* ClassCastException}.
1020		*
1021		* @return the next task, or {@code null} if none are available
1022		*/
#	Line 1025 | Line 1033 | public abstract class ForkJoinTask<V> im
1033		* {@code null} result does not necessarily imply quiescence
1034		* of the pool this task is operating in.  This method is designed
1035		* primarily to support extensions, and is unlikely to be useful
1036	<	* otherwise.  This method may be invoked only from within
1037	<	* ForkJoinTask computations (as may be determined using method
1038	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1039	<	* result in exceptions or errors, possibly including
1040	<	* ClassCastException.
1036	>	* otherwise.
1037	>	*
1038	>	* <p>This method may be invoked only from within {@code
1039	>	* ForkJoinTask} computations (as may be determined using method
1040	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1041	>	* result in exceptions or errors, possibly including {@code
1042	>	* ClassCastException}.
1043		*
1044		* @return a task, or {@code null} if none are available
1045		*/
#	Line 1038 | Line 1048 | public abstract class ForkJoinTask<V> im
1048		.pollTask();
1049		}
1050
1051	<	// adaptors
1051	>	/**
1052	>	* Adaptor for Runnables. This implements RunnableFuture
1053	>	* to be compliant with AbstractExecutorService constraints
1054	>	* when used in ForkJoinPool.
1055	>	*/
1056	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1057	>	implements RunnableFuture<T> {
1058	>	final Runnable runnable;
1059	>	final T resultOnCompletion;
1060	>	T result;
1061	>	AdaptedRunnable(Runnable runnable, T result) {
1062	>	if (runnable == null) throw new NullPointerException();
1063	>	this.runnable = runnable;
1064	>	this.resultOnCompletion = result;
1065	>	}
1066	>	public T getRawResult() { return result; }
1067	>	public void setRawResult(T v) { result = v; }
1068	>	public boolean exec() {
1069	>	runnable.run();
1070	>	result = resultOnCompletion;
1071	>	return true;
1072	>	}
1073	>	public void run() { invoke(); }
1074	>	private static final long serialVersionUID = 5232453952276885070L;
1075	>	}
1076	>
1077	>	/**
1078	>	* Adaptor for Callables
1079	>	*/
1080	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1081	>	implements RunnableFuture<T> {
1082	>	final Callable<? extends T> callable;
1083	>	T result;
1084	>	AdaptedCallable(Callable<? extends T> callable) {
1085	>	if (callable == null) throw new NullPointerException();
1086	>	this.callable = callable;
1087	>	}
1088	>	public T getRawResult() { return result; }
1089	>	public void setRawResult(T v) { result = v; }
1090	>	public boolean exec() {
1091	>	try {
1092	>	result = callable.call();
1093	>	return true;
1094	>	} catch (Error err) {
1095	>	throw err;
1096	>	} catch (RuntimeException rex) {
1097	>	throw rex;
1098	>	} catch (Exception ex) {
1099	>	throw new RuntimeException(ex);
1100	>	}
1101	>	}
1102	>	public void run() { invoke(); }
1103	>	private static final long serialVersionUID = 2838392045355241008L;
1104	>	}
1105
1106		/**
1107	<	* Returns a new ForkJoinTask that performs the {@code run}
1108	<	* method of the given Runnable as its action, and returns a null
1109	<	* result upon {@code join}.
1107	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1108	>	* method of the given {@code Runnable} as its action, and returns
1109	>	* a null result upon {@link #join}.
1110		*
1111		* @param runnable the runnable action
1112		* @return the task
1113		*/
1114	<	public static ForkJoinTask<Void> adapt(Runnable runnable) {
1115	<	return new ForkJoinPool.AdaptedRunnable<Void>(runnable, null);
1114	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1115	>	return new AdaptedRunnable<Void>(runnable, null);
1116		}
1117
1118		/**
1119	<	* Returns a new ForkJoinTask that performs the {@code run}
1120	<	* method of the given Runnable as its action, and returns the
1121	<	* given result upon {@code join}.
1119	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1120	>	* method of the given {@code Runnable} as its action, and returns
1121	>	* the given result upon {@link #join}.
1122		*
1123		* @param runnable the runnable action
1124		* @param result the result upon completion
1125		* @return the task
1126		*/
1127		public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1128	<	return new ForkJoinPool.AdaptedRunnable<T>(runnable, result);
1128	>	return new AdaptedRunnable<T>(runnable, result);
1129		}
1130
1131		/**
1132	<	* Returns a new ForkJoinTask that performs the {@code call}
1133	<	* method of the given Callable as its action, and returns its
1134	<	* result upon {@code join}, translating any checked
1135	<	* exceptions encountered into {@code RuntimeException}.
1132	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1133	>	* method of the given {@code Callable} as its action, and returns
1134	>	* its result upon {@link #join}, translating any checked exceptions
1135	>	* encountered into {@code RuntimeException}.
1136		*
1137		* @param callable the callable action
1138		* @return the task
1139		*/
1140	<	public static <T> ForkJoinTask<T> adapt(Callable<T> callable) {
1141	<	return new ForkJoinPool.AdaptedCallable<T>(callable);
1140	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1141	>	return new AdaptedCallable<T>(callable);
1142		}
1143
1144		// Serialization support
#	Line 1083 | Line 1146 | public abstract class ForkJoinTask<V> im
1146		private static final long serialVersionUID = -7721805057305804111L;
1147
1148		/**
1149	<	* Save the state to a stream.
1149	>	* Saves the state to a stream.
1150		*
1151		* @serialData the current run status and the exception thrown
1152		* during execution, or {@code null} if none
#	Line 1096 | Line 1159 | public abstract class ForkJoinTask<V> im
1159		}
1160
1161		/**
1162	<	* Reconstitute the instance from a stream.
1162	>	* Reconstitutes the instance from a stream.
1163		*
1164		* @param s the stream
1165		*/
1166		private void readObject(java.io.ObjectInputStream s)
1167		throws java.io.IOException, ClassNotFoundException {
1168		s.defaultReadObject();
1169	<	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1107	<	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1169	>	status |= SIGNAL; // conservatively set external signal
1170		Object ex = s.readObject();
1171		if (ex != null)
1172	<	setDoneExceptionally((Throwable) ex);
1172	>	setExceptionalCompletion((Throwable) ex);
1173		}
1174
1175		// Unsafe mechanics

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