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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.27 by dl, Sun Aug 2 11:54:31 2009 UTC vs.
Revision 1.62 by dl, Fri Sep 17 14:24:56 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
#	Line 22 | Line 23 | import java.util.WeakHashMap;
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(ForkJoinTask...) invokeAll}.  However, this class also
32	>	* provides a number of other methods that can come into play in
33	>	* advanced usages, as well as extension mechanics that allow
34	>	* support of new forms of fork/join 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:
65		* The {@link Future#get} methods support interruptible and/or timed
66		* waits for completion and report results using {@code Future}
67	<	* 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
68	<	* equivalent to {@code fork(); join()} but always attempts to
69	<	* begin execution in the current thread. The "<em>quiet</em>" forms
70	<	* of these methods do not extract results or report exceptions. These
67	>	* conventions. Method {@link #invoke} is semantically
68	>	* equivalent to {@code fork(); join()} but always attempts to begin
69	>	* execution in the current thread. The "<em>quiet</em>" forms of
70	>	* these methods do not extract results or report exceptions. These
71		* may be useful when a set of tasks are being executed, and you need
72		* to delay processing of results or exceptions until all complete.
73		* Method {@code invokeAll} (available in multiple versions)
74		* performs the most common form of parallel invocation: forking a set
75		* of tasks and joining them all.
76		*
77	<	* <p> The ForkJoinTask class is not usually directly subclassed.
77	>	* <p>The execution status of tasks may be queried at several levels
78	>	* of detail: {@link #isDone} is true if a task completed in any way
79	>	* (including the case where a task was cancelled without executing);
80	>	* {@link #isCompletedNormally} is true if a task completed without
81	>	* cancellation or encountering an exception; {@link #isCancelled} is
82	>	* true if the task was cancelled (in which case {@link #getException}
83	>	* returns a {@link java.util.concurrent.CancellationException}); and
84	>	* {@link #isCompletedAbnormally} is true if a task was either
85	>	* cancelled or encountered an exception, in which case {@link
86	>	* #getException} will return either the encountered exception or
87	>	* {@link java.util.concurrent.CancellationException}.
88	>	*
89	>	* <p>The ForkJoinTask class is not usually directly subclassed.
90		* Instead, you subclass one of the abstract classes that support a
91		* particular style of fork/join processing, typically {@link
92		* RecursiveAction} for computations that do not return results, or
#	Line 83 | Line 95 | import java.util.WeakHashMap;
95		* established in a constructor, and then defines a {@code compute}
96		* method that somehow uses the control methods supplied by this base
97		* class. While these methods have {@code public} access (to allow
98	<	* instances of different task subclasses to call each others
98	>	* instances of different task subclasses to call each other's
99		* methods), some of them may only be called from within other
100		* ForkJoinTasks (as may be determined using method {@link
101		* #inForkJoinPool}).  Attempts to invoke them in other contexts
102		* result in exceptions or errors, possibly including
103	<	* ClassCastException.
103	>	* {@code ClassCastException}.
104		*
105	<	* <p>Most base support methods are {@code final} because their
106	<	* implementations are intrinsically tied to the underlying
107	<	* lightweight task scheduling framework, and so cannot be overridden.
108	<	* Developers creating new basic styles of fork/join processing should
109	<	* minimally implement {@code protected} methods
110	<	* {@link #exec}, {@link #setRawResult}, and
111	<	* {@link #getRawResult}, while also introducing an abstract
112	<	* computational method that can be implemented in its subclasses,
113	<	* possibly relying on other {@code protected} methods provided
102	<	* by this class.
105	>	* <p>Most base support methods are {@code final}, to prevent
106	>	* overriding of implementations that are intrinsically tied to the
107	>	* underlying lightweight task scheduling framework.  Developers
108	>	* creating new basic styles of fork/join processing should minimally
109	>	* implement {@code protected} methods {@link #exec}, {@link
110	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
111	>	* an abstract computational method that can be implemented in its
112	>	* subclasses, possibly relying on other {@code protected} methods
113	>	* provided by this class.
114		*
115		* <p>ForkJoinTasks should perform relatively small amounts of
116	<	* computations, otherwise splitting into smaller tasks. As a very
117	<	* rough rule of thumb, a task should perform more than 100 and less
118	<	* than 10000 basic computational steps. If tasks are too big, then
119	<	* parallelism cannot improve throughput. If too small, then memory
120	<	* and internal task maintenance overhead may overwhelm processing.
116	>	* computation. Large tasks should be split into smaller subtasks,
117	>	* usually via recursive decomposition. As a very rough rule of thumb,
118	>	* a task should perform more than 100 and less than 10000 basic
119	>	* computational steps. If tasks are too big, then parallelism cannot
120	>	* improve throughput. If too small, then memory and internal task
121	>	* maintenance overhead may overwhelm processing.
122		*
123	<	* <p>This class provides {@code adapt} methods for {@link
124	<	* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that
125	<	* may be of use when mixing execution of ForkJoinTasks with other
126	<	* kinds of tasks. When all tasks are of this form, consider using a
115	<	* pool in {@link ForkJoinPool#setAsyncMode}.
123	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
124	>	* and {@link Callable}, that may be of use when mixing execution of
125	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
126	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
127		*
128	<	* <p>ForkJoinTasks are {@code Serializable}, which enables them
129	<	* to be used in extensions such as remote execution frameworks. It is
130	<	* in general sensible to serialize tasks only before or after, but
131	<	* not during execution. Serialization is not relied on during
121	<	* execution itself.
128	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
129	>	* used in extensions such as remote execution frameworks. It is
130	>	* sensible to serialize tasks only before or after, but not during,
131	>	* execution. Serialization is not relied on during execution itself.
132		*
133		* @since 1.7
134		* @author Doug Lea
135		*/
136		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
137
138	<	/**
139	<	* Run control status bits packed into a single int to minimize
140	<	* footprint and to ensure atomicity (via CAS).  Status is
141	<	* initially zero, and takes on nonnegative values until
142	<	* completed, upon which status holds COMPLETED. CANCELLED, or
143	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
144	<	* blocking waits by other threads have SIGNAL_MASK bits set --
145	<	* bit 15 for external (nonFJ) waits, and the rest a count of
146	<	* waiting FJ threads.  (This representation relies on
147	<	* ForkJoinPool max thread limits). Completion of a stolen task
148	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
149	<	* though suboptimal for some purposes, we use basic builtin
150	<	* wait/notify to take advantage of "monitor inflation" in JVMs
151	<	* that we would otherwise need to emulate to avoid adding further
152	<	* per-task bookkeeping overhead. Note that bits 16-28 are
153	<	* currently unused. Also value 0x80000000 is available as spare
154	<	* completion value.
138	>	/*
139	>	* See the internal documentation of class ForkJoinPool for a
140	>	* general implementation overview.  ForkJoinTasks are mainly
141	>	* responsible for maintaining their "status" field amidst relays
142	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
143	>	* methods of this class are more-or-less layered into (1) basic
144	>	* status maintenance (2) execution and awaiting completion (3)
145	>	* user-level methods that additionally report results. This is
146	>	* sometimes hard to see because this file orders exported methods
147	>	* in a way that flows well in javadocs. In particular, most
148	>	* join mechanics are in method quietlyJoin, below.
149	>	*/
150	>
151	>	/*
152	>	* The status field holds run control status bits packed into a
153	>	* single int to minimize footprint and to ensure atomicity (via
154	>	* CAS).  Status is initially zero, and takes on nonnegative
155	>	* values until completed, upon which status holds value
156	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
157	>	* waits by other threads have the SIGNAL bit set.  Completion of
158	>	* a stolen task with SIGNAL set awakens any waiters via
159	>	* notifyAll. Even though suboptimal for some purposes, we use
160	>	* basic builtin wait/notify to take advantage of "monitor
161	>	* inflation" in JVMs that we would otherwise need to emulate to
162	>	* avoid adding further per-task bookkeeping overhead.  We want
163	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
164	>	* techniques, so use some odd coding idioms that tend to avoid
165	>	* them.
166		*/
167	+
168	+	/** The run status of this task */
169		volatile int status; // accessed directly by pool and workers
170
171	<	static final int COMPLETION_MASK      = 0xe0000000;
172	<	static final int NORMAL               = 0xe0000000; // == mask
173	<	static final int CANCELLED            = 0xc0000000;
174	<	static final int EXCEPTIONAL          = 0xa0000000;
152	<	static final int SIGNAL_MASK          = 0x0000ffff;
153	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
154	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
171	>	private static final int NORMAL      = -1;
172	>	private static final int CANCELLED   = -2;
173	>	private static final int EXCEPTIONAL = -3;
174	>	private static final int SIGNAL      =  1;
175
176		/**
177		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 165 | Line 185 | public abstract class ForkJoinTask<V> im
185		Collections.synchronizedMap
186		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
187
188	<	// within-package utilities
169	<
170	<	/**
171	<	* Gets current worker thread, or null if not a worker thread.
172	<	*/
173	<	static ForkJoinWorkerThread getWorker() {
174	<	Thread t = Thread.currentThread();
175	<	return ((t instanceof ForkJoinWorkerThread) ?
176	<	(ForkJoinWorkerThread) t : null);
177	<	}
178	<
179	<	final boolean casStatus(int cmp, int val) {
180	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
181	<	}
182	<
183	<	/**
184	<	* Workaround for not being able to rethrow unchecked exceptions.
185	<	*/
186	<	static void rethrowException(Throwable ex) {
187	<	if (ex != null)
188	<	UNSAFE.throwException(ex);
189	<	}
190	<
191	<	// Setting completion status
188	>	// Maintaining completion status
189
190		/**
191	<	* Marks completion and wakes up threads waiting to join this task.
191	>	* Marks completion and wakes up threads waiting to join this task,
192	>	* also clearing signal request bits.
193		*
194		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
195		*/
196	<	final void setCompletion(int completion) {
197	<	ForkJoinPool pool = getPool();
198	<	if (pool != null) {
199	<	int s; // Clear signal bits while setting completion status
200	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
201	<
202	<	if ((s & SIGNAL_MASK) != 0) {
205	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
206	<	pool.updateRunningCount(s);
207	<	synchronized (this) { notifyAll(); }
196	>	private void setCompletion(int completion) {
197	>	int s;
198	>	while ((s = status) >= 0) {
199	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
200	>	if (s != 0)
201	>	synchronized (this) { notifyAll(); }
202	>	break;
203		}
204		}
210	–	else
211	–	externallySetCompletion(completion);
212	–	}
213	–
214	–	/**
215	–	* Version of setCompletion for non-FJ threads.  Leaves signal
216	–	* bits for unblocked threads to adjust, and always notifies.
217	–	*/
218	–	private void externallySetCompletion(int completion) {
219	–	int s;
220	–	do {} while ((s = status) >= 0 &&
221	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
222	–	synchronized (this) { notifyAll(); }
223	–	}
224	–
225	–	/**
226	–	* Sets status to indicate normal completion.
227	–	*/
228	–	final void setNormalCompletion() {
229	–	// Try typical fast case -- single CAS, no signal, not already done.
230	–	// Manually expand casStatus to improve chances of inlining it
231	–	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
232	–	setCompletion(NORMAL);
205		}
206
235	–	// internal waiting and notification
236	–
207		/**
208	<	* Performs the actual monitor wait for awaitDone.
208	>	* Records exception and sets exceptional completion.
209	>	*
210	>	* @return status on exit
211		*/
212	<	private void doAwaitDone() {
213	<	// Minimize lock bias and in/de-flation effects by maximizing
214	<	// chances of waiting inside sync
243	<	try {
244	<	while (status >= 0)
245	<	synchronized (this) { if (status >= 0) wait(); }
246	<	} catch (InterruptedException ie) {
247	<	onInterruptedWait();
248	<	}
212	>	private void setExceptionalCompletion(Throwable rex) {
213	>	exceptionMap.put(this, rex);
214	>	setCompletion(EXCEPTIONAL);
215		}
216
217		/**
218	<	* Performs the actual timed monitor wait for awaitDone.
218	>	* Blocks a worker thread until completion. Called only by
219	>	* pool. Currently unused -- pool-based waits use timeout
220	>	* version below.
221		*/
222	<	private void doAwaitDone(long startTime, long nanos) {
223	<	synchronized (this) {
222	>	final void internalAwaitDone() {
223	>	int s;         // the odd construction reduces lock bias effects
224	>	while ((s = status) >= 0) {
225		try {
226	<	while (status >= 0) {
227	<	long nt = nanos - (System.nanoTime() - startTime);
228	<	if (nt <= 0)
260	<	break;
261	<	wait(nt / 1000000, (int) (nt % 1000000));
226	>	synchronized (this) {
227	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
228	>	wait();
229		}
230		} catch (InterruptedException ie) {
231	<	onInterruptedWait();
265	<	}
266	<	}
267	<	}
268	<
269	<	// Awaiting completion
270	<
271	<	/**
272	<	* Sets status to indicate there is joiner, then waits for join,
273	<	* surrounded with pool notifications.
274	<	*
275	<	* @return status upon exit
276	<	*/
277	<	private int awaitDone(ForkJoinWorkerThread w,
278	<	boolean maintainParallelism) {
279	<	ForkJoinPool pool = (w == null) ? null : w.pool;
280	<	int s;
281	<	while ((s = status) >= 0) {
282	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
283	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
284	<	doAwaitDone();
285	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
286	<	adjustPoolCountsOnUnblock(pool);
287	<	break;
231	>	cancelIfTerminating();
232		}
233		}
290	–	return s;
234		}
235
236		/**
237	<	* Timed version of awaitDone
237	>	* Blocks a worker thread until completed or timed out.  Called
238	>	* only by pool.
239		*
240	<	* @return status upon exit
240	>	* @return status on exit
241		*/
242	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
299	<	ForkJoinPool pool = (w == null) ? null : w.pool;
242	>	final int internalAwaitDone(long millis) {
243		int s;
244	<	while ((s = status) >= 0) {
245	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
246	<	long startTime = System.nanoTime();
247	<	if (pool == null || !pool.preJoin(this, false))
248	<	doAwaitDone(startTime, nanos);
306	<	if ((s = status) >= 0) {
307	<	adjustPoolCountsOnCancelledWait(pool);
308	<	s = status;
244	>	if ((s = status) >= 0) {
245	>	try {
246	>	synchronized (this) {
247	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
248	>	wait(millis, 0);
249		}
250	<	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
251	<	adjustPoolCountsOnUnblock(pool);
312	<	break;
250	>	} catch (InterruptedException ie) {
251	>	cancelIfTerminating();
252		}
253	+	s = status;
254		}
255		return s;
256		}
257
258		/**
259	<	* Notifies pool that thread is unblocked. Called by signalled
320	<	* threads when woken by non-FJ threads (which is atypical).
259	>	* Blocks a non-worker-thread until completion.
260		*/
261	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
261	>	private void externalAwaitDone() {
262		int s;
263	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
264	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
265	<	pool.updateRunningCount(s);
266	<	}
267	<
268	<	/**
269	<	* Notifies pool to adjust counts on cancelled or timed out wait.
270	<	*/
271	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
272	<	if (pool != null) {
273	<	int s;
274	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
275	<	if (casStatus(s, s - 1)) {
337	<	pool.updateRunningCount(1);
263	>	while ((s = status) >= 0) {
264	>	synchronized (this) {
265	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
266	>	boolean interrupted = false;
267	>	while (status >= 0) {
268	>	try {
269	>	wait();
270	>	} catch (InterruptedException ie) {
271	>	interrupted = true;
272	>	}
273	>	}
274	>	if (interrupted)
275	>	Thread.currentThread().interrupt();
276		break;
277		}
278		}
#	Line 342 | Line 280 | public abstract class ForkJoinTask<V> im
280		}
281
282		/**
283	<	* Handles interruptions during waits.
284	<	*/
285	<	private void onInterruptedWait() {
348	<	ForkJoinWorkerThread w = getWorker();
349	<	if (w == null)
350	<	Thread.currentThread().interrupt(); // re-interrupt
351	<	else if (w.isTerminating())
352	<	cancelIgnoringExceptions();
353	<	// else if FJworker, ignore interrupt
354	<	}
355	<
356	<	// Recording and reporting exceptions
357	<
358	<	private void setDoneExceptionally(Throwable rex) {
359	<	exceptionMap.put(this, rex);
360	<	setCompletion(EXCEPTIONAL);
361	<	}
362	<
363	<	/**
364	<	* Throws the exception associated with status s.
365	<	*
366	<	* @throws the exception
367	<	*/
368	<	private void reportException(int s) {
369	<	if ((s &= COMPLETION_MASK) < NORMAL) {
370	<	if (s == CANCELLED)
371	<	throw new CancellationException();
372	<	else
373	<	rethrowException(exceptionMap.get(this));
374	<	}
375	<	}
376	<
377	<	/**
378	<	* Returns result or throws exception using j.u.c.Future conventions.
379	<	* Only call when {@code isDone} known to be true.
380	<	*/
381	<	private V reportFutureResult()
382	<	throws ExecutionException, InterruptedException {
383	<	int s = status & COMPLETION_MASK;
384	<	if (s < NORMAL) {
385	<	Throwable ex;
386	<	if (s == CANCELLED)
387	<	throw new CancellationException();
388	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
389	<	throw new ExecutionException(ex);
390	<	if (Thread.interrupted())
391	<	throw new InterruptedException();
392	<	}
393	<	return getRawResult();
394	<	}
395	<
396	<	/**
397	<	* Returns result or throws exception using j.u.c.Future conventions
398	<	* with timeouts.
399	<	*/
400	<	private V reportTimedFutureResult()
401	<	throws InterruptedException, ExecutionException, TimeoutException {
402	<	Throwable ex;
403	<	int s = status & COMPLETION_MASK;
404	<	if (s == NORMAL)
405	<	return getRawResult();
406	<	if (s == CANCELLED)
407	<	throw new CancellationException();
408	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
409	<	throw new ExecutionException(ex);
410	<	if (Thread.interrupted())
411	<	throw new InterruptedException();
412	<	throw new TimeoutException();
413	<	}
414	<
415	<	// internal execution methods
416	<
417	<	/**
418	<	* Calls exec, recording completion, and rethrowing exception if
419	<	* encountered. Caller should normally check status before calling.
420	<	*
421	<	* @return true if completed normally
422	<	*/
423	<	private boolean tryExec() {
424	<	try { // try block must contain only call to exec
425	<	if (!exec())
426	<	return false;
427	<	} catch (Throwable rex) {
428	<	setDoneExceptionally(rex);
429	<	rethrowException(rex);
430	<	return false; // not reached
431	<	}
432	<	setNormalCompletion();
433	<	return true;
434	<	}
435	<
436	<	/**
437	<	* Main execution method used by worker threads. Invokes
438	<	* base computation unless already complete.
283	>	* Unless done, calls exec and records status if completed, but
284	>	* doesn't wait for completion otherwise. Primary execution method
285	>	* for ForkJoinWorkerThread.
286		*/
287		final void quietlyExec() {
441	–	if (status >= 0) {
442	–	try {
443	–	if (!exec())
444	–	return;
445	–	} catch (Throwable rex) {
446	–	setDoneExceptionally(rex);
447	–	return;
448	–	}
449	–	setNormalCompletion();
450	–	}
451	–	}
452	–
453	–	/**
454	–	* Calls exec(), recording but not rethrowing exception.
455	–	* Caller should normally check status before calling.
456	–	*
457	–	* @return true if completed normally
458	–	*/
459	–	private boolean tryQuietlyInvoke() {
288		try {
289	<	if (!exec())
290	<	return false;
289	>	if (status < 0 || !exec())
290	>	return;
291		} catch (Throwable rex) {
292	<	setDoneExceptionally(rex);
293	<	return false;
466	<	}
467	<	setNormalCompletion();
468	<	return true;
469	<	}
470	<
471	<	/**
472	<	* Cancels, ignoring any exceptions it throws.
473	<	*/
474	<	final void cancelIgnoringExceptions() {
475	<	try {
476	<	cancel(false);
477	<	} catch (Throwable ignore) {
292	>	setExceptionalCompletion(rex);
293	>	return;
294		}
295	<	}
480	<
481	<	/**
482	<	* Main implementation of helpJoin
483	<	*/
484	<	private int busyJoin(ForkJoinWorkerThread w) {
485	<	int s;
486	<	ForkJoinTask<?> t;
487	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
488	<	t.quietlyExec();
489	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
295	>	setCompletion(NORMAL); // must be outside try block
296		}
297
298		// public methods
#	Line 494 | Line 300 | public abstract class ForkJoinTask<V> im
300		/**
301		* Arranges to asynchronously execute this task.  While it is not
302		* necessarily enforced, it is a usage error to fork a task more
303	<	* than once unless it has completed and been reinitialized.  This
304	<	* method may be invoked only from within ForkJoinTask
305	<	* computations (as may be determined using method {@link
306	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
307	<	* in exceptions or errors, possibly including ClassCastException.
303	>	* than once unless it has completed and been reinitialized.
304	>	* Subsequent modifications to the state of this task or any data
305	>	* it operates on are not necessarily consistently observable by
306	>	* any thread other than the one executing it unless preceded by a
307	>	* call to {@link #join} or related methods, or a call to {@link
308	>	* #isDone} returning {@code true}.
309	>	*
310	>	* <p>This method may be invoked only from within {@code
311	>	* ForkJoinTask} computations (as may be determined using method
312	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
313	>	* result in exceptions or errors, possibly including {@code
314	>	* ClassCastException}.
315		*
316	<	* @return {@code this}, to simplify usage.
316	>	* @return {@code this}, to simplify usage
317		*/
318		public final ForkJoinTask<V> fork() {
319		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 509 | Line 322 | public abstract class ForkJoinTask<V> im
322		}
323
324		/**
325	<	* Returns the result of the computation when it is ready.
326	<	* This method differs from {@code get} in that abnormal
327	<	* completion results in RuntimeExceptions or Errors, not
328	<	* ExecutionExceptions.
325	>	* Returns the result of the computation when it {@link #isDone is done}.
326	>	* This method differs from {@link #get()} in that
327	>	* abnormal completion results in {@code RuntimeException} or
328	>	* {@code Error}, not {@code ExecutionException}.
329		*
330		* @return the computed result
331		*/
332		public final V join() {
333	<	ForkJoinWorkerThread w = getWorker();
334	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
335	<	reportException(awaitDone(w, true));
333	>	quietlyJoin();
334	>	Throwable ex;
335	>	if (status < NORMAL && (ex = getException()) != null)
336	>	UNSAFE.throwException(ex);
337		return getRawResult();
338		}
339
340		/**
341		* Commences performing this task, awaits its completion if
342	<	* necessary, and return its result.
342	>	* necessary, and returns its result, or throws an (unchecked)
343	>	* {@code RuntimeException} or {@code Error} if the underlying
344	>	* computation did so.
345		*
530	–	* @throws Throwable (a RuntimeException, Error, or unchecked
531	–	* exception) if the underlying computation did so
346		* @return the computed result
347		*/
348		public final V invoke() {
349	<	if (status >= 0 && tryExec())
350	<	return getRawResult();
351	<	else
352	<	return join();
349	>	quietlyInvoke();
350	>	Throwable ex;
351	>	if (status < NORMAL && (ex = getException()) != null)
352	>	UNSAFE.throwException(ex);
353	>	return getRawResult();
354		}
355
356		/**
357		* Forks the given tasks, returning when {@code isDone} holds for
358	<	* each task or an exception is encountered. This method may be
359	<	* invoked only from within ForkJoinTask computations (as may be
360	<	* determined using method {@link #inForkJoinPool}). Attempts to
361	<	* invoke in other contexts result in exceptions or errors,
362	<	* possibly including ClassCastException.
358	>	* each task or an (unchecked) exception is encountered, in which
359	>	* case the exception is rethrown. If more than one task
360	>	* encounters an exception, then this method throws any one of
361	>	* these exceptions. If any task encounters an exception, the
362	>	* other may be cancelled. However, the execution status of
363	>	* individual tasks is not guaranteed upon exceptional return. The
364	>	* status of each task may be obtained using {@link
365	>	* #getException()} and related methods to check if they have been
366	>	* cancelled, completed normally or exceptionally, or left
367	>	* unprocessed.
368	>	*
369	>	* <p>This method may be invoked only from within {@code
370	>	* ForkJoinTask} computations (as may be determined using method
371	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
372	>	* result in exceptions or errors, possibly including {@code
373	>	* ClassCastException}.
374		*
375		* @param t1 the first task
376		* @param t2 the second task
377		* @throws NullPointerException if any task is null
552	–	* @throws RuntimeException or Error if a task did so
378		*/
379	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
379	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
380		t2.fork();
381		t1.invoke();
382		t2.join();
#	Line 559 | Line 384 | public abstract class ForkJoinTask<V> im
384
385		/**
386		* Forks the given tasks, returning when {@code isDone} holds for
387	<	* each task or an exception is encountered. If any task
388	<	* encounters an exception, others may be, but are not guaranteed
389	<	* to be, cancelled.  This method may be invoked only from within
390	<	* ForkJoinTask computations (as may be determined using method
391	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
392	<	* result in exceptions or errors, possibly including
393	<	* ClassCastException.
394	<	*
395	<	* Overloadings of this method exist for the special cases
396	<	* of one to four arguments.
387	>	* each task or an (unchecked) exception is encountered, in which
388	>	* case the exception is rethrown. If more than one task
389	>	* encounters an exception, then this method throws any one of
390	>	* these exceptions. If any task encounters an exception, others
391	>	* may be cancelled. However, the execution status of individual
392	>	* tasks is not guaranteed upon exceptional return. The status of
393	>	* each task may be obtained using {@link #getException()} and
394	>	* related methods to check if they have been cancelled, completed
395	>	* normally or exceptionally, or left unprocessed.
396	>	*
397	>	* <p>This method may be invoked only from within {@code
398	>	* ForkJoinTask} computations (as may be determined using method
399	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
400	>	* result in exceptions or errors, possibly including {@code
401	>	* ClassCastException}.
402		*
403		* @param tasks the tasks
404	<	* @throws NullPointerException if tasks or any element are null
575	<	* @throws RuntimeException or Error if any task did so
404	>	* @throws NullPointerException if any task is null
405		*/
406		public static void invokeAll(ForkJoinTask<?>... tasks) {
407		Throwable ex = null;
#	Line 587 | Line 416 | public abstract class ForkJoinTask<V> im
416		t.fork();
417		else {
418		t.quietlyInvoke();
419	<	if (ex == null)
419	>	if (ex == null && t.status < NORMAL)
420		ex = t.getException();
421		}
422		}
#	Line 598 | Line 427 | public abstract class ForkJoinTask<V> im
427		t.cancel(false);
428		else {
429		t.quietlyJoin();
430	<	if (ex == null)
430	>	if (ex == null && t.status < NORMAL)
431		ex = t.getException();
432		}
433		}
434		}
435		if (ex != null)
436	<	rethrowException(ex);
436	>	UNSAFE.throwException(ex);
437		}
438
439		/**
440	<	* Forks all tasks in the collection, returning when {@code
441	<	* isDone} holds for each task or an exception is encountered. If
442	<	* any task encounters an exception, others may be, but are not
443	<	* guaranteed to be, cancelled.  This method may be invoked only
444	<	* from within ForkJoinTask computations (as may be determined
445	<	* using method {@link #inForkJoinPool}). Attempts to invoke in
446	<	* other contexts result in exceptions or errors, possibly
447	<	* including ClassCastException.
440	>	* Forks all tasks in the specified collection, returning when
441	>	* {@code isDone} holds for each task or an (unchecked) exception
442	>	* is encountered, in which case the exception is rethrown. If
443	>	* more than one task encounters an exception, then this method
444	>	* throws any one of these exceptions. If any task encounters an
445	>	* exception, others may be cancelled. However, the execution
446	>	* status of individual tasks is not guaranteed upon exceptional
447	>	* return. The status of each task may be obtained using {@link
448	>	* #getException()} and related methods to check if they have been
449	>	* cancelled, completed normally or exceptionally, or left
450	>	* unprocessed.
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 collection of tasks
459		* @return the tasks argument, to simplify usage
460		* @throws NullPointerException if tasks or any element are null
623	–	* @throws RuntimeException or Error if any task did so
461		*/
462		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
463	<	if (!(tasks instanceof List<?>)) {
463	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
464		invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
465		return tasks;
466		}
#	Line 642 | Line 479 | public abstract class ForkJoinTask<V> im
479		t.fork();
480		else {
481		t.quietlyInvoke();
482	<	if (ex == null)
482	>	if (ex == null && t.status < NORMAL)
483		ex = t.getException();
484		}
485		}
#	Line 653 | Line 490 | public abstract class ForkJoinTask<V> im
490		t.cancel(false);
491		else {
492		t.quietlyJoin();
493	<	if (ex == null)
493	>	if (ex == null && t.status < NORMAL)
494		ex = t.getException();
495		}
496		}
497		}
498		if (ex != null)
499	<	rethrowException(ex);
499	>	UNSAFE.throwException(ex);
500		return tasks;
501		}
502
503		/**
504	<	* Returns {@code true} if the computation performed by this task
505	<	* has completed (or has been cancelled).
506	<	*
507	<	* @return {@code true} if this computation has completed
508	<	*/
509	<	public final boolean isDone() {
510	<	return status < 0;
674	<	}
675	<
676	<	/**
677	<	* Returns {@code true} if this task was cancelled.
678	<	*
679	<	* @return {@code true} if this task was cancelled
680	<	*/
681	<	public final boolean isCancelled() {
682	<	return (status & COMPLETION_MASK) == CANCELLED;
683	<	}
684	<
685	<	/**
686	<	* Asserts that the results of this task's computation will not be
687	<	* used. If a cancellation occurs before attempting to execute this
688	<	* task, execution will be suppressed, {@link #isCancelled}
689	<	* will report true, and {@link #join} will result in a
690	<	* {@code CancellationException} being thrown. Otherwise, when
691	<	* cancellation races with completion, there are no guarantees
692	<	* about whether {@code isCancelled} will report {@code true},
693	<	* whether {@code join} will return normally or via an exception,
694	<	* or whether these behaviors will remain consistent upon repeated
695	<	* invocation.
504	>	* Attempts to cancel execution of this task. This attempt will
505	>	* fail if the task has already completed, has already been
506	>	* cancelled, or could not be cancelled for some other reason. If
507	>	* successful, and this task has not started when cancel is
508	>	* called, execution of this task is suppressed, {@link
509	>	* #isCancelled} will report true, and {@link #join} will result
510	>	* in a {@code CancellationException} being thrown.
511		*
512		* <p>This method may be overridden in subclasses, but if so, must
513		* still ensure that these minimal properties hold. In particular,
514	<	* the cancel method itself must not throw exceptions.
514	>	* the {@code cancel} method itself must not throw exceptions.
515		*
516	<	* <p> This method is designed to be invoked by <em>other</em>
516	>	* <p>This method is designed to be invoked by <em>other</em>
517		* tasks. To terminate the current task, you can just return or
518		* throw an unchecked exception from its computation method, or
519		* invoke {@link #completeExceptionally}.
520		*
521		* @param mayInterruptIfRunning this value is ignored in the
522	<	* default implementation because tasks are not in general
522	>	* default implementation because tasks are not
523		* cancelled via interruption
524		*
525		* @return {@code true} if this task is now cancelled
526		*/
527		public boolean cancel(boolean mayInterruptIfRunning) {
528		setCompletion(CANCELLED);
529	<	return (status & COMPLETION_MASK) == CANCELLED;
529	>	return status == CANCELLED;
530	>	}
531	>
532	>	/**
533	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
534	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
535	>	* exceptions, but if it does anyway, we have no recourse during
536	>	* shutdown, so guard against this case.
537	>	*/
538	>	final void cancelIgnoringExceptions() {
539	>	try {
540	>	cancel(false);
541	>	} catch (Throwable ignore) {
542	>	}
543	>	}
544	>
545	>	/**
546	>	* Cancels if current thread is a terminating worker thread,
547	>	* ignoring any exceptions thrown by cancel.
548	>	*/
549	>	final void cancelIfTerminating() {
550	>	Thread t = Thread.currentThread();
551	>	if ((t instanceof ForkJoinWorkerThread) &&
552	>	((ForkJoinWorkerThread) t).isTerminating()) {
553	>	try {
554	>	cancel(false);
555	>	} catch (Throwable ignore) {
556	>	}
557	>	}
558	>	}
559	>
560	>	public final boolean isDone() {
561	>	return status < 0;
562	>	}
563	>
564	>	public final boolean isCancelled() {
565	>	return status == CANCELLED;
566		}
567
568		/**
#	Line 720 | Line 571 | public abstract class ForkJoinTask<V> im
571		* @return {@code true} if this task threw an exception or was cancelled
572		*/
573		public final boolean isCompletedAbnormally() {
574	<	return (status & COMPLETION_MASK) < NORMAL;
574	>	return status < NORMAL;
575	>	}
576	>
577	>	/**
578	>	* Returns {@code true} if this task completed without throwing an
579	>	* exception and was not cancelled.
580	>	*
581	>	* @return {@code true} if this task completed without throwing an
582	>	* exception and was not cancelled
583	>	*/
584	>	public final boolean isCompletedNormally() {
585	>	return status == NORMAL;
586		}
587
588		/**
589		* Returns the exception thrown by the base computation, or a
590	<	* CancellationException if cancelled, or null if none or if the
591	<	* method has not yet completed.
590	>	* {@code CancellationException} if cancelled, or {@code null} if
591	>	* none or if the method has not yet completed.
592		*
593		* @return the exception, or {@code null} if none
594		*/
595		public final Throwable getException() {
596	<	int s = status & COMPLETION_MASK;
597	<	if (s >= NORMAL)
598	<	return null;
599	<	if (s == CANCELLED)
738	<	return new CancellationException();
739	<	return exceptionMap.get(this);
596	>	int s = status;
597	>	return ((s >= NORMAL)    ? null :
598	>	(s == CANCELLED) ? new CancellationException() :
599	>	exceptionMap.get(this));
600		}
601
602		/**
#	Line 749 | Line 609 | public abstract class ForkJoinTask<V> im
609		* overridable, but overridden versions must invoke {@code super}
610		* implementation to maintain guarantees.
611		*
612	<	* @param ex the exception to throw. If this exception is
613	<	* not a RuntimeException or Error, the actual exception thrown
614	<	* will be a RuntimeException with cause ex.
612	>	* @param ex the exception to throw. If this exception is not a
613	>	* {@code RuntimeException} or {@code Error}, the actual exception
614	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
615		*/
616		public void completeExceptionally(Throwable ex) {
617	<	setDoneExceptionally((ex instanceof RuntimeException) ||
618	<	(ex instanceof Error) ? ex :
619	<	new RuntimeException(ex));
617	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
618	>	(ex instanceof Error) ? ex :
619	>	new RuntimeException(ex));
620		}
621
622		/**
623		* Completes this task, and if not already aborted or cancelled,
624	<	* returning a {@code null} result upon {@code join} and related
625	<	* operations. This method may be used to provide results for
626	<	* asynchronous tasks, or to provide alternative handling for
627	<	* tasks that would not otherwise complete normally. Its use in
628	<	* other situations is discouraged. This method is
629	<	* overridable, but overridden versions must invoke {@code super}
630	<	* implementation to maintain guarantees.
624	>	* returning the given value as the result of subsequent
625	>	* invocations of {@code join} and related operations. This method
626	>	* may be used to provide results for asynchronous tasks, or to
627	>	* provide alternative handling for tasks that would not otherwise
628	>	* complete normally. Its use in other situations is
629	>	* discouraged. This method is overridable, but overridden
630	>	* versions must invoke {@code super} implementation to maintain
631	>	* guarantees.
632		*
633		* @param value the result value for this task
634		*/
#	Line 775 | Line 636 | public abstract class ForkJoinTask<V> im
636		try {
637		setRawResult(value);
638		} catch (Throwable rex) {
639	<	setDoneExceptionally(rex);
639	>	setExceptionalCompletion(rex);
640		return;
641		}
642	<	setNormalCompletion();
782	<	}
783	<
784	<	public final V get() throws InterruptedException, ExecutionException {
785	<	ForkJoinWorkerThread w = getWorker();
786	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
787	<	awaitDone(w, true);
788	<	return reportFutureResult();
789	<	}
790	<
791	<	public final V get(long timeout, TimeUnit unit)
792	<	throws InterruptedException, ExecutionException, TimeoutException {
793	<	long nanos = unit.toNanos(timeout);
794	<	ForkJoinWorkerThread w = getWorker();
795	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
796	<	awaitDone(w, nanos);
797	<	return reportTimedFutureResult();
642	>	setCompletion(NORMAL);
643		}
644
645		/**
646	<	* Possibly executes other tasks until this task is ready, then
802	<	* returns the result of the computation.  This method may be more
803	<	* efficient than {@code join}, but is only applicable when
804	<	* there are no potential dependencies between continuation of the
805	<	* current task and that of any other task that might be executed
806	<	* while helping. (This usually holds for pure divide-and-conquer
807	<	* tasks). This method may be invoked only from within
808	<	* ForkJoinTask computations (as may be determined using method
809	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
810	<	* result in exceptions or errors, possibly including
811	<	* ClassCastException.
812	<	*
813	<	* @return the computed result
646	>	* @throws CancellationException {@inheritDoc}
647		*/
648	<	public final V helpJoin() {
649	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
650	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
651	<	reportException(busyJoin(w));
648	>	public final V get() throws InterruptedException, ExecutionException {
649	>	int s;
650	>	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
651	>	quietlyJoin();
652	>	s = status;
653	>	}
654	>	else {
655	>	while ((s = status) >= 0) {
656	>	synchronized (this) { // interruptible form of awaitDone
657	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
658	>	s, SIGNAL)) {
659	>	while (status >= 0)
660	>	wait();
661	>	}
662	>	}
663	>	}
664	>	}
665	>	if (s < NORMAL) {
666	>	Throwable ex;
667	>	if (s == CANCELLED)
668	>	throw new CancellationException();
669	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
670	>	throw new ExecutionException(ex);
671	>	}
672		return getRawResult();
673		}
674
675		/**
676	<	* Possibly executes other tasks until this task is ready.  This
824	<	* method may be invoked only from within ForkJoinTask
825	<	* computations (as may be determined using method {@link
826	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
827	<	* in exceptions or errors, possibly including ClassCastException.
676	>	* @throws CancellationException {@inheritDoc}
677		*/
678	<	public final void quietlyHelpJoin() {
679	<	if (status >= 0) {
680	<	ForkJoinWorkerThread w =
681	<	(ForkJoinWorkerThread) Thread.currentThread();
682	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
683	<	busyJoin(w);
678	>	public final V get(long timeout, TimeUnit unit)
679	>	throws InterruptedException, ExecutionException, TimeoutException {
680	>	Thread t = Thread.currentThread();
681	>	ForkJoinPool pool;
682	>	if (t instanceof ForkJoinWorkerThread) {
683	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
684	>	if (status >= 0 && w.unpushTask(this))
685	>	quietlyExec();
686	>	pool = w.pool;
687		}
688	+	else
689	+	pool = null;
690	+	/*
691	+	* Timed wait loop intermixes cases for FJ (pool != null) and
692	+	* non FJ threads. For FJ, decrement pool count but don't try
693	+	* for replacement; increment count on completion. For non-FJ,
694	+	* deal with interrupts. This is messy, but a little less so
695	+	* than is splitting the FJ and nonFJ cases.
696	+	*/
697	+	boolean interrupted = false;
698	+	boolean dec = false; // true if pool count decremented
699	+	long nanos = unit.toNanos(timeout);
700	+	for (;;) {
701	+	if (pool == null && Thread.interrupted()) {
702	+	interrupted = true;
703	+	break;
704	+	}
705	+	int s = status;
706	+	if (s < 0)
707	+	break;
708	+	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
709	+	long startTime = System.nanoTime();
710	+	long nt; // wait time
711	+	while (status >= 0 &&
712	+	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
713	+	if (pool != null && !dec)
714	+	dec = pool.tryDecrementRunningCount();
715	+	else {
716	+	long ms = nt / 1000000;
717	+	int ns = (int) (nt % 1000000);
718	+	try {
719	+	synchronized (this) {
720	+	if (status >= 0)
721	+	wait(ms, ns);
722	+	}
723	+	} catch (InterruptedException ie) {
724	+	if (pool != null)
725	+	cancelIfTerminating();
726	+	else {
727	+	interrupted = true;
728	+	break;
729	+	}
730	+	}
731	+	}
732	+	}
733	+	break;
734	+	}
735	+	}
736	+	if (pool != null && dec)
737	+	pool.incrementRunningCount();
738	+	if (interrupted)
739	+	throw new InterruptedException();
740	+	int es = status;
741	+	if (es != NORMAL) {
742	+	Throwable ex;
743	+	if (es == CANCELLED)
744	+	throw new CancellationException();
745	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
746	+	throw new ExecutionException(ex);
747	+	throw new TimeoutException();
748	+	}
749	+	return getRawResult();
750		}
751
752		/**
753	<	* Joins this task, without returning its result or throwing an
753	>	* Joins this task, without returning its result or throwing its
754		* exception. This method may be useful when processing
755		* collections of tasks when some have been cancelled or otherwise
756		* known to have aborted.
757		*/
758		public final void quietlyJoin() {
759	<	if (status >= 0) {
760	<	ForkJoinWorkerThread w = getWorker();
761	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
762	<	awaitDone(w, true);
759	>	Thread t;
760	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
761	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
762	>	if (status >= 0) {
763	>	if (w.unpushTask(this)) {
764	>	boolean completed;
765	>	try {
766	>	completed = exec();
767	>	} catch (Throwable rex) {
768	>	setExceptionalCompletion(rex);
769	>	return;
770	>	}
771	>	if (completed) {
772	>	setCompletion(NORMAL);
773	>	return;
774	>	}
775	>	}
776	>	w.joinTask(this);
777	>	}
778		}
779	+	else
780	+	externalAwaitDone();
781		}
782
783		/**
784		* Commences performing this task and awaits its completion if
785	<	* necessary, without returning its result or throwing an
786	<	* exception. This method may be useful when processing
856	<	* collections of tasks when some have been cancelled or otherwise
857	<	* known to have aborted.
785	>	* necessary, without returning its result or throwing its
786	>	* exception.
787		*/
788		public final void quietlyInvoke() {
789	<	if (status >= 0 && !tryQuietlyInvoke())
790	<	quietlyJoin();
789	>	if (status >= 0) {
790	>	boolean completed;
791	>	try {
792	>	completed = exec();
793	>	} catch (Throwable rex) {
794	>	setExceptionalCompletion(rex);
795	>	return;
796	>	}
797	>	if (completed)
798	>	setCompletion(NORMAL);
799	>	else
800	>	quietlyJoin();
801	>	}
802		}
803
804		/**
805		* Possibly executes tasks until the pool hosting the current task
806	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
807	<	* designs in which many tasks are forked, but none are explicitly
808	<	* joined, instead executing them until all are processed.  This
809	<	* method may be invoked only from within ForkJoinTask
810	<	* computations (as may be determined using method {@link
811	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
812	<	* in exceptions or errors, possibly including ClassCastException.
806	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
807	>	* be of use in designs in which many tasks are forked, but none
808	>	* are explicitly joined, instead executing them until all are
809	>	* processed.
810	>	*
811	>	* <p>This method may be invoked only from within {@code
812	>	* ForkJoinTask} computations (as may be determined using method
813	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
814	>	* result in exceptions or errors, possibly including {@code
815	>	* ClassCastException}.
816		*/
817		public static void helpQuiesce() {
818		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 882 | Line 825 | public abstract class ForkJoinTask<V> im
825		* this task, but only if reuse occurs when this task has either
826		* never been forked, or has been forked, then completed and all
827		* outstanding joins of this task have also completed. Effects
828	<	* under any other usage conditions are not guaranteed, and are
829	<	* discouraged. This method may be useful when executing
828	>	* under any other usage conditions are not guaranteed.
829	>	* This method may be useful when executing
830		* pre-constructed trees of subtasks in loops.
831		*/
832		public void reinitialize() {
833	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
833	>	if (status == EXCEPTIONAL)
834		exceptionMap.remove(this);
835		status = 0;
836		}
#	Line 922 | Line 865 | public abstract class ForkJoinTask<V> im
865		* by the current thread, and has not commenced executing in
866		* another thread.  This method may be useful when arranging
867		* alternative local processing of tasks that could have been, but
868	<	* were not, stolen. This method may be invoked only from within
869	<	* ForkJoinTask computations (as may be determined using method
870	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
871	<	* result in exceptions or errors, possibly including
872	<	* ClassCastException.
868	>	* were not, stolen.
869	>	*
870	>	* <p>This method may be invoked only from within {@code
871	>	* ForkJoinTask} computations (as may be determined using method
872	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
873	>	* result in exceptions or errors, possibly including {@code
874	>	* ClassCastException}.
875		*
876		* @return {@code true} if unforked
877		*/
#	Line 939 | Line 884 | public abstract class ForkJoinTask<V> im
884		* Returns an estimate of the number of tasks that have been
885		* forked by the current worker thread but not yet executed. This
886		* value may be useful for heuristic decisions about whether to
887	<	* fork other tasks.  This method may be invoked only from within
888	<	* ForkJoinTask computations (as may be determined using method
889	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
890	<	* result in exceptions or errors, possibly including
891	<	* ClassCastException.
887	>	* fork other tasks.
888	>	*
889	>	* <p>This method may be invoked only from within {@code
890	>	* ForkJoinTask} computations (as may be determined using method
891	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
892	>	* result in exceptions or errors, possibly including {@code
893	>	* ClassCastException}.
894	>	*
895		* @return the number of tasks
896		*/
897		public static int getQueuedTaskCount() {
#	Line 959 | Line 907 | public abstract class ForkJoinTask<V> im
907		* usages of ForkJoinTasks, at steady state, each worker should
908		* aim to maintain a small constant surplus (for example, 3) of
909		* tasks, and to process computations locally if this threshold is
910	<	* exceeded.  This method may be invoked only from within
911	<	* ForkJoinTask computations (as may be determined using method
912	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
913	<	* result in exceptions or errors, possibly including
914	<	* ClassCastException.  *
910	>	* exceeded.
911	>	*
912	>	* <p>This method may be invoked only from within {@code
913	>	* ForkJoinTask} computations (as may be determined using method
914	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
915	>	* result in exceptions or errors, possibly including {@code
916	>	* ClassCastException}.
917	>	*
918		* @return the surplus number of tasks, which may be negative
919		*/
920		public static int getSurplusQueuedTaskCount() {
#	Line 999 | Line 950 | public abstract class ForkJoinTask<V> im
950		* called otherwise. The return value controls whether this task
951		* is considered to be done normally. It may return false in
952		* asynchronous actions that require explicit invocations of
953	<	* {@link #complete} to become joinable. It may throw exceptions
954	<	* to indicate abnormal exit.
953	>	* {@link #complete} to become joinable. It may also throw an
954	>	* (unchecked) exception to indicate abnormal exit.
955		*
956		* @return {@code true} if completed normally
1006	–	* @throws Error or RuntimeException if encountered during computation
957		*/
958		protected abstract boolean exec();
959
#	Line 1015 | Line 965 | public abstract class ForkJoinTask<V> im
965		* null even if a task exists but cannot be accessed without
966		* contention with other threads.  This method is designed
967		* primarily to support extensions, and is unlikely to be useful
968	<	* otherwise.  This method may be invoked only from within
969	<	* ForkJoinTask computations (as may be determined using method
970	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
971	<	* result in exceptions or errors, possibly including
972	<	* ClassCastException.
968	>	* otherwise.
969	>	*
970	>	* <p>This method may be invoked only from within {@code
971	>	* ForkJoinTask} computations (as may be determined using method
972	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
973	>	* result in exceptions or errors, possibly including {@code
974	>	* ClassCastException}.
975		*
976		* @return the next task, or {@code null} if none are available
977		*/
#	Line 1032 | Line 984 | public abstract class ForkJoinTask<V> im
984		* Unschedules and returns, without executing, the next task
985		* queued by the current thread but not yet executed.  This method
986		* is designed primarily to support extensions, and is unlikely to
987	<	* be useful otherwise.  This method may be invoked only from
988	<	* within ForkJoinTask computations (as may be determined using
989	<	* method {@link #inForkJoinPool}). Attempts to invoke in other
990	<	* contexts result in exceptions or errors, possibly including
991	<	* ClassCastException.
987	>	* be useful otherwise.
988	>	*
989	>	* <p>This method may be invoked only from within {@code
990	>	* ForkJoinTask} computations (as may be determined using method
991	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
992	>	* result in exceptions or errors, possibly including {@code
993	>	* ClassCastException}.
994		*
995		* @return the next task, or {@code null} if none are available
996		*/
#	Line 1053 | Line 1007 | public abstract class ForkJoinTask<V> im
1007		* {@code null} result does not necessarily imply quiescence
1008		* of the pool this task is operating in.  This method is designed
1009		* primarily to support extensions, and is unlikely to be useful
1010	<	* otherwise.  This method may be invoked only from within
1011	<	* ForkJoinTask computations (as may be determined using method
1012	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1013	<	* result in exceptions or errors, possibly including
1014	<	* ClassCastException.
1010	>	* otherwise.
1011	>	*
1012	>	* <p>This method may be invoked only from within {@code
1013	>	* ForkJoinTask} computations (as may be determined using method
1014	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1015	>	* result in exceptions or errors, possibly including {@code
1016	>	* ClassCastException}.
1017		*
1018		* @return a task, or {@code null} if none are available
1019		*/
#	Line 1122 | Line 1078 | public abstract class ForkJoinTask<V> im
1078		}
1079
1080		/**
1081	<	* Returns a new ForkJoinTask that performs the {@code run}
1082	<	* method of the given Runnable as its action, and returns a null
1083	<	* result upon {@code join}.
1081	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1082	>	* method of the given {@code Runnable} as its action, and returns
1083	>	* a null result upon {@link #join}.
1084		*
1085		* @param runnable the runnable action
1086		* @return the task
#	Line 1134 | Line 1090 | public abstract class ForkJoinTask<V> im
1090		}
1091
1092		/**
1093	<	* Returns a new ForkJoinTask that performs the {@code run}
1094	<	* method of the given Runnable as its action, and returns the
1095	<	* given result upon {@code join}.
1093	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1094	>	* method of the given {@code Runnable} as its action, and returns
1095	>	* the given result upon {@link #join}.
1096		*
1097		* @param runnable the runnable action
1098		* @param result the result upon completion
#	Line 1147 | Line 1103 | public abstract class ForkJoinTask<V> im
1103		}
1104
1105		/**
1106	<	* Returns a new ForkJoinTask that performs the {@code call}
1107	<	* method of the given Callable as its action, and returns its
1108	<	* result upon {@code join}, translating any checked
1109	<	* exceptions encountered into {@code RuntimeException}.
1106	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1107	>	* method of the given {@code Callable} as its action, and returns
1108	>	* its result upon {@link #join}, translating any checked exceptions
1109	>	* encountered into {@code RuntimeException}.
1110		*
1111		* @param callable the callable action
1112		* @return the task
#	Line 1164 | Line 1120 | public abstract class ForkJoinTask<V> im
1120		private static final long serialVersionUID = -7721805057305804111L;
1121
1122		/**
1123	<	* Save the state to a stream.
1123	>	* Saves the state to a stream (that is, serializes it).
1124		*
1125		* @serialData the current run status and the exception thrown
1126		* during execution, or {@code null} if none
#	Line 1177 | Line 1133 | public abstract class ForkJoinTask<V> im
1133		}
1134
1135		/**
1136	<	* Reconstitute the instance from a stream.
1136	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1137		*
1138		* @param s the stream
1139		*/
1140		private void readObject(java.io.ObjectInputStream s)
1141		throws java.io.IOException, ClassNotFoundException {
1142		s.defaultReadObject();
1187	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1188	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1143		Object ex = s.readObject();
1144		if (ex != null)
1145	<	setDoneExceptionally((Throwable) ex);
1145	>	setExceptionalCompletion((Throwable) ex);
1146		}
1147
1148		// Unsafe mechanics

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