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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.20 by jsr166, Sun Jul 26 05:55:34 2009 UTC vs.
Revision 1.56 by jsr166, Sat Sep 4 00:21:31 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}
30	<	* and {@code join}, or derivatives such as
31	<	* {@code invokeAll}.  However, this class also provides a number
32	<	* of other methods that can come into play in advanced usages, as
33	<	* well as extension mechanics that allow support of new forms of
34	<	* 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:
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
69	<	* equivalent to {@code fork(); join()} but always attempts to
70	<	* begin execution in the current thread. The "<em>quiet</em>" forms
71	<	* 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.  Normally, a concrete
91	>	* particular style of fork/join processing, typically {@link
92	>	* RecursiveAction} for computations that do not return results, or
93	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
94		* ForkJoinTask subclass declares fields comprising its parameters,
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.
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	<	* {@code exec}, {@code setRawResult}, and
111	<	* {@code 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
101	<	* 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 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
114	<	* 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	>	* COMPLETED. 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;
145	<	static final int SIGNAL_MASK          = 0x0000ffff;
146	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
147	<	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 158 | Line 185 | public abstract class ForkJoinTask<V> im
185		Collections.synchronizedMap
186		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
187
188	<	// within-package utilities
162	<
163	<	/**
164	<	* Gets current worker thread, or null if not a worker thread.
165	<	*/
166	<	static ForkJoinWorkerThread getWorker() {
167	<	Thread t = Thread.currentThread();
168	<	return ((t instanceof ForkJoinWorkerThread) ?
169	<	(ForkJoinWorkerThread) t : null);
170	<	}
171	<
172	<	final boolean casStatus(int cmp, int val) {
173	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
174	<	}
175	<
176	<	/**
177	<	* Workaround for not being able to rethrow unchecked exceptions.
178	<	*/
179	<	static void rethrowException(Throwable ex) {
180	<	if (ex != null)
181	<	UNSAFE.throwException(ex);
182	<	}
183	<
184	<	// 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) {
198	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
199	<	pool.updateRunningCount(s);
200	<	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		}
203	–	else
204	–	externallySetCompletion(completion);
205	–	}
206	–
207	–	/**
208	–	* Version of setCompletion for non-FJ threads.  Leaves signal
209	–	* bits for unblocked threads to adjust, and always notifies.
210	–	*/
211	–	private void externallySetCompletion(int completion) {
212	–	int s;
213	–	do {} while ((s = status) >= 0 &&
214	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
215	–	synchronized (this) { notifyAll(); }
205		}
206
207		/**
208	<	* Sets status to indicate normal completion.
208	>	* Records exception and sets exceptional completion.
209	>	*
210	>	* @return status on exit
211		*/
212	<	final void setNormalCompletion() {
213	<	// Try typical fast case -- single CAS, no signal, not already done.
214	<	// Manually expand casStatus to improve chances of inlining it
224	<	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
225	<	setCompletion(NORMAL);
226	<	}
227	<
228	<	// internal waiting and notification
229	<
230	<	/**
231	<	* Performs the actual monitor wait for awaitDone.
232	<	*/
233	<	private void doAwaitDone() {
234	<	// Minimize lock bias and in/de-flation effects by maximizing
235	<	// chances of waiting inside sync
236	<	try {
237	<	while (status >= 0)
238	<	synchronized (this) { if (status >= 0) wait(); }
239	<	} catch (InterruptedException ie) {
240	<	onInterruptedWait();
241	<	}
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)
253	<	break;
254	<	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();
258	<	}
259	<	}
260	<	}
261	<
262	<	// Awaiting completion
263	<
264	<	/**
265	<	* Sets status to indicate there is joiner, then waits for join,
266	<	* surrounded with pool notifications.
267	<	*
268	<	* @return status upon exit
269	<	*/
270	<	private int awaitDone(ForkJoinWorkerThread w,
271	<	boolean maintainParallelism) {
272	<	ForkJoinPool pool = (w == null) ? null : w.pool;
273	<	int s;
274	<	while ((s = status) >= 0) {
275	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
276	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
277	<	doAwaitDone();
278	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
279	<	adjustPoolCountsOnUnblock(pool);
280	<	break;
231	>	cancelIfTerminating();
232		}
233		}
283	–	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) {
292	<	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);
299	<	if ((s = status) >= 0) {
300	<	adjustPoolCountsOnCancelledWait(pool);
301	<	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);
305	<	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
313	<	* 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)) {
330	<	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 335 | Line 280 | public abstract class ForkJoinTask<V> im
280		}
281
282		/**
283	<	* Handles interruptions during waits.
284	<	*/
285	<	private void onInterruptedWait() {
341	<	ForkJoinWorkerThread w = getWorker();
342	<	if (w == null)
343	<	Thread.currentThread().interrupt(); // re-interrupt
344	<	else if (w.isTerminating())
345	<	cancelIgnoringExceptions();
346	<	// else if FJworker, ignore interrupt
347	<	}
348	<
349	<	// Recording and reporting exceptions
350	<
351	<	private void setDoneExceptionally(Throwable rex) {
352	<	exceptionMap.put(this, rex);
353	<	setCompletion(EXCEPTIONAL);
354	<	}
355	<
356	<	/**
357	<	* Throws the exception associated with status s.
358	<	*
359	<	* @throws the exception
360	<	*/
361	<	private void reportException(int s) {
362	<	if ((s &= COMPLETION_MASK) < NORMAL) {
363	<	if (s == CANCELLED)
364	<	throw new CancellationException();
365	<	else
366	<	rethrowException(exceptionMap.get(this));
367	<	}
368	<	}
369	<
370	<	/**
371	<	* Returns result or throws exception using j.u.c.Future conventions.
372	<	* Only call when {@code isDone} known to be true.
373	<	*/
374	<	private V reportFutureResult()
375	<	throws ExecutionException, InterruptedException {
376	<	int s = status & COMPLETION_MASK;
377	<	if (s < NORMAL) {
378	<	Throwable ex;
379	<	if (s == CANCELLED)
380	<	throw new CancellationException();
381	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
382	<	throw new ExecutionException(ex);
383	<	if (Thread.interrupted())
384	<	throw new InterruptedException();
385	<	}
386	<	return getRawResult();
387	<	}
388	<
389	<	/**
390	<	* Returns result or throws exception using j.u.c.Future conventions
391	<	* with timeouts.
392	<	*/
393	<	private V reportTimedFutureResult()
394	<	throws InterruptedException, ExecutionException, TimeoutException {
395	<	Throwable ex;
396	<	int s = status & COMPLETION_MASK;
397	<	if (s == NORMAL)
398	<	return getRawResult();
399	<	if (s == CANCELLED)
400	<	throw new CancellationException();
401	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
402	<	throw new ExecutionException(ex);
403	<	if (Thread.interrupted())
404	<	throw new InterruptedException();
405	<	throw new TimeoutException();
406	<	}
407	<
408	<	// internal execution methods
409	<
410	<	/**
411	<	* Calls exec, recording completion, and rethrowing exception if
412	<	* encountered. Caller should normally check status before calling.
413	<	*
414	<	* @return true if completed normally
415	<	*/
416	<	private boolean tryExec() {
417	<	try { // try block must contain only call to exec
418	<	if (!exec())
419	<	return false;
420	<	} catch (Throwable rex) {
421	<	setDoneExceptionally(rex);
422	<	rethrowException(rex);
423	<	return false; // not reached
424	<	}
425	<	setNormalCompletion();
426	<	return true;
427	<	}
428	<
429	<	/**
430	<	* Main execution method used by worker threads. Invokes
431	<	* 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() {
434	–	if (status >= 0) {
435	–	try {
436	–	if (!exec())
437	–	return;
438	–	} catch (Throwable rex) {
439	–	setDoneExceptionally(rex);
440	–	return;
441	–	}
442	–	setNormalCompletion();
443	–	}
444	–	}
445	–
446	–	/**
447	–	* Calls exec(), recording but not rethrowing exception.
448	–	* Caller should normally check status before calling.
449	–	*
450	–	* @return true if completed normally
451	–	*/
452	–	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;
459	<	}
460	<	setNormalCompletion();
461	<	return true;
462	<	}
463	<
464	<	/**
465	<	* Cancels, ignoring any exceptions it throws.
466	<	*/
467	<	final void cancelIgnoringExceptions() {
468	<	try {
469	<	cancel(false);
470	<	} catch (Throwable ignore) {
292	>	setExceptionalCompletion(rex);
293	>	return;
294		}
295	<	}
473	<
474	<	/**
475	<	* Main implementation of helpJoin
476	<	*/
477	<	private int busyJoin(ForkJoinWorkerThread w) {
478	<	int s;
479	<	ForkJoinTask<?> t;
480	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
481	<	t.quietlyExec();
482	<	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 487 | 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</code>, to simplify usage.
316	>	* @return {@code this}, to simplify usage
317		*/
318		public final ForkJoinTask<V> fork() {
319		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 502 | 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	>	* exception if the underlying computation did so.
344		*
523	–	* @throws Throwable (a RuntimeException, Error, or unchecked
524	–	* exception) if the underlying computation did so
345		* @return the computed result
346		*/
347		public final V invoke() {
348	<	if (status >= 0 && tryExec())
349	<	return getRawResult();
350	<	else
351	<	return join();
348	>	quietlyInvoke();
349	>	Throwable ex;
350	>	if (status < NORMAL && (ex = getException()) != null)
351	>	UNSAFE.throwException(ex);
352	>	return getRawResult();
353		}
354
355		/**
356	<	* Forks both tasks, returning when {@code isDone} holds for
357	<	* both of them or an exception is encountered. This method may be
358	<	* invoked only from within ForkJoinTask computations (as may be
359	<	* determined using method {@link #inForkJoinPool}). Attempts to
360	<	* invoke in other contexts result in exceptions or errors,
361	<	* possibly including ClassCastException.
362	<	*
363	<	* @param t1 one task
364	<	* @param t2 the other task
365	<	* @throws NullPointerException if t1 or t2 are null
366	<	* @throws RuntimeException or Error if either task did so
356	>	* Forks the given tasks, returning when {@code isDone} holds for
357	>	* each task or an (unchecked) exception is encountered, in which
358	>	* case the exception is rethrown.  If either task encounters an
359	>	* exception, the other one may be, but is not guaranteed to be,
360	>	* cancelled.  If both tasks throw an exception, then this method
361	>	* throws one of them.  The individual status of each task may be
362	>	* checked using {@link #getException()} and related methods.
363	>	*
364	>	* <p>This method may be invoked only from within {@code
365	>	* ForkJoinTask} computations (as may be determined using method
366	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
367	>	* result in exceptions or errors, possibly including {@code
368	>	* ClassCastException}.
369	>	*
370	>	* @param t1 the first task
371	>	* @param t2 the second task
372	>	* @throws NullPointerException if any task is null
373		*/
374	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
374	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
375		t2.fork();
376		t1.invoke();
377		t2.join();
378		}
379
380		/**
381	<	* Forks the given tasks, returning when {@code isDone} holds
382	<	* for all of them. If any task encounters an exception, others
383	<	* may be cancelled.  This method may be invoked only from within
384	<	* ForkJoinTask computations (as may be determined using method
385	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
386	<	* result in exceptions or errors, possibly including
387	<	* ClassCastException.
381	>	* Forks the given tasks, returning when {@code isDone} holds for
382	>	* each task or an (unchecked) exception is encountered, in which
383	>	* case the exception is rethrown. If any task encounters an
384	>	* exception, others may be, but are not guaranteed to be,
385	>	* cancelled.  If more than one task encounters an exception, then
386	>	* this method throws any one of these exceptions.  The individual
387	>	* status of each task may be checked using {@link #getException()}
388	>	* and related methods.
389	>	*
390	>	* <p>This method may be invoked only from within {@code
391	>	* ForkJoinTask} computations (as may be determined using method
392	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
393	>	* result in exceptions or errors, possibly including {@code
394	>	* ClassCastException}.
395		*
396	<	* @param tasks the array of tasks
397	<	* @throws NullPointerException if tasks or any element are null
564	<	* @throws RuntimeException or Error if any task did so
396	>	* @param tasks the tasks
397	>	* @throws NullPointerException if any task is null
398		*/
399		public static void invokeAll(ForkJoinTask<?>... tasks) {
400		Throwable ex = null;
#	Line 576 | Line 409 | public abstract class ForkJoinTask<V> im
409		t.fork();
410		else {
411		t.quietlyInvoke();
412	<	if (ex == null)
412	>	if (ex == null && t.status < NORMAL)
413		ex = t.getException();
414		}
415		}
#	Line 587 | Line 420 | public abstract class ForkJoinTask<V> im
420		t.cancel(false);
421		else {
422		t.quietlyJoin();
423	<	if (ex == null)
423	>	if (ex == null && t.status < NORMAL)
424		ex = t.getException();
425		}
426		}
427		}
428		if (ex != null)
429	<	rethrowException(ex);
429	>	UNSAFE.throwException(ex);
430		}
431
432		/**
433	<	* Forks all tasks in the collection, returning when
434	<	* {@code isDone} holds for all of them. If any task
435	<	* encounters an exception, others may be cancelled.  This method
436	<	* may be invoked only from within ForkJoinTask computations (as
437	<	* may be determined using method {@link
438	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
439	<	* in exceptions or errors, possibly including ClassCastException.
433	>	* Forks all tasks in the specified collection, returning when
434	>	* {@code isDone} holds for each task or an (unchecked) exception
435	>	* is encountered.  If any task encounters an exception, others
436	>	* may be, but are not guaranteed to be, cancelled.  If more than
437	>	* one task encounters an exception, then this method throws any
438	>	* one of these exceptions.  The individual status of each task
439	>	* may be checked using {@link #getException()} and related
440	>	* methods.  The behavior of this operation is undefined if the
441	>	* specified collection is modified while the operation is in
442	>	* progress.
443	>	*
444	>	* <p>This method may be invoked only from within {@code
445	>	* ForkJoinTask} computations (as may be determined using method
446	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
447	>	* result in exceptions or errors, possibly including {@code
448	>	* ClassCastException}.
449		*
450		* @param tasks the collection of tasks
451		* @return the tasks argument, to simplify usage
452		* @throws NullPointerException if tasks or any element are null
611	–	* @throws RuntimeException or Error if any task did so
453		*/
454		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
455	<	if (!(tasks instanceof List<?>)) {
455	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
456		invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
457		return tasks;
458		}
#	Line 630 | Line 471 | public abstract class ForkJoinTask<V> im
471		t.fork();
472		else {
473		t.quietlyInvoke();
474	<	if (ex == null)
474	>	if (ex == null && t.status < NORMAL)
475		ex = t.getException();
476		}
477		}
#	Line 641 | Line 482 | public abstract class ForkJoinTask<V> im
482		t.cancel(false);
483		else {
484		t.quietlyJoin();
485	<	if (ex == null)
485	>	if (ex == null && t.status < NORMAL)
486		ex = t.getException();
487		}
488		}
489		}
490		if (ex != null)
491	<	rethrowException(ex);
491	>	UNSAFE.throwException(ex);
492		return tasks;
493		}
494
495		/**
496	<	* Returns true if the computation performed by this task has
497	<	* completed (or has been cancelled).
498	<	*
499	<	* @return true if this computation has completed
500	<	*/
501	<	public final boolean isDone() {
502	<	return status < 0;
662	<	}
663	<
664	<	/**
665	<	* Returns true if this task was cancelled.
666	<	*
667	<	* @return true if this task was cancelled
668	<	*/
669	<	public final boolean isCancelled() {
670	<	return (status & COMPLETION_MASK) == CANCELLED;
671	<	}
672	<
673	<	/**
674	<	* Asserts that the results of this task's computation will not be
675	<	* used. If a cancellation occurs before attempting to execute this
676	<	* task, then execution will be suppressed, {@code isCancelled}
677	<	* will report true, and {@code join} will result in a
678	<	* {@code CancellationException} being thrown. Otherwise, when
679	<	* cancellation races with completion, there are no guarantees
680	<	* about whether {@code isCancelled} will report true, whether
681	<	* {@code join} will return normally or via an exception, or
682	<	* whether these behaviors will remain consistent upon repeated
683	<	* invocation.
496	>	* Attempts to cancel execution of this task. This attempt will
497	>	* fail if the task has already completed, has already been
498	>	* cancelled, or could not be cancelled for some other reason. If
499	>	* successful, and this task has not started when cancel is
500	>	* called, execution of this task is suppressed, {@link
501	>	* #isCancelled} will report true, and {@link #join} will result
502	>	* in a {@code CancellationException} being thrown.
503		*
504		* <p>This method may be overridden in subclasses, but if so, must
505		* still ensure that these minimal properties hold. In particular,
506	<	* the cancel method itself must not throw exceptions.
506	>	* the {@code cancel} method itself must not throw exceptions.
507		*
508	<	* <p> This method is designed to be invoked by <em>other</em>
508	>	* <p>This method is designed to be invoked by <em>other</em>
509		* tasks. To terminate the current task, you can just return or
510		* throw an unchecked exception from its computation method, or
511	<	* invoke {@code completeExceptionally}.
511	>	* invoke {@link #completeExceptionally}.
512		*
513		* @param mayInterruptIfRunning this value is ignored in the
514	<	* default implementation because tasks are not in general
514	>	* default implementation because tasks are not
515		* cancelled via interruption
516		*
517	<	* @return true if this task is now cancelled
517	>	* @return {@code true} if this task is now cancelled
518		*/
519		public boolean cancel(boolean mayInterruptIfRunning) {
520		setCompletion(CANCELLED);
521	<	return (status & COMPLETION_MASK) == CANCELLED;
521	>	return status == CANCELLED;
522		}
523
524		/**
525	<	* Returns true if this task threw an exception or was cancelled.
525	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
526	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
527	>	* exceptions, but if it does anyway, we have no recourse during
528	>	* shutdown, so guard against this case.
529	>	*/
530	>	final void cancelIgnoringExceptions() {
531	>	try {
532	>	cancel(false);
533	>	} catch (Throwable ignore) {
534	>	}
535	>	}
536	>
537	>	/**
538	>	* Cancels if current thread is a terminating worker thread,
539	>	* ignoring any exceptions thrown by cancel.
540	>	*/
541	>	final void cancelIfTerminating() {
542	>	Thread t = Thread.currentThread();
543	>	if ((t instanceof ForkJoinWorkerThread) &&
544	>	((ForkJoinWorkerThread) t).isTerminating()) {
545	>	try {
546	>	cancel(false);
547	>	} catch (Throwable ignore) {
548	>	}
549	>	}
550	>	}
551	>
552	>	public final boolean isDone() {
553	>	return status < 0;
554	>	}
555	>
556	>	public final boolean isCancelled() {
557	>	return status == CANCELLED;
558	>	}
559	>
560	>	/**
561	>	* Returns {@code true} if this task threw an exception or was cancelled.
562		*
563	<	* @return true if this task threw an exception or was cancelled
563	>	* @return {@code true} if this task threw an exception or was cancelled
564		*/
565		public final boolean isCompletedAbnormally() {
566	<	return (status & COMPLETION_MASK) < NORMAL;
566	>	return status < NORMAL;
567	>	}
568	>
569	>	/**
570	>	* Returns {@code true} if this task completed without throwing an
571	>	* exception and was not cancelled.
572	>	*
573	>	* @return {@code true} if this task completed without throwing an
574	>	* exception and was not cancelled
575	>	*/
576	>	public final boolean isCompletedNormally() {
577	>	return status == NORMAL;
578		}
579
580		/**
581		* Returns the exception thrown by the base computation, or a
582	<	* CancellationException if cancelled, or null if none or if the
583	<	* method has not yet completed.
582	>	* {@code CancellationException} if cancelled, or {@code null} if
583	>	* none or if the method has not yet completed.
584		*
585	<	* @return the exception, or null if none
585	>	* @return the exception, or {@code null} if none
586		*/
587		public final Throwable getException() {
588	<	int s = status & COMPLETION_MASK;
589	<	if (s >= NORMAL)
590	<	return null;
591	<	if (s == CANCELLED)
726	<	return new CancellationException();
727	<	return exceptionMap.get(this);
588	>	int s = status;
589	>	return ((s >= NORMAL)    ? null :
590	>	(s == CANCELLED) ? new CancellationException() :
591	>	exceptionMap.get(this));
592		}
593
594		/**
#	Line 733 | Line 597 | public abstract class ForkJoinTask<V> im
597		* {@code join} and related operations. This method may be used
598		* to induce exceptions in asynchronous tasks, or to force
599		* completion of tasks that would not otherwise complete.  Its use
600	<	* in other situations is likely to be wrong.  This method is
600	>	* in other situations is discouraged.  This method is
601		* overridable, but overridden versions must invoke {@code super}
602		* implementation to maintain guarantees.
603		*
604	<	* @param ex the exception to throw. If this exception is
605	<	* not a RuntimeException or Error, the actual exception thrown
606	<	* will be a RuntimeException with cause ex.
604	>	* @param ex the exception to throw. If this exception is not a
605	>	* {@code RuntimeException} or {@code Error}, the actual exception
606	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
607		*/
608		public void completeExceptionally(Throwable ex) {
609	<	setDoneExceptionally((ex instanceof RuntimeException) ||
610	<	(ex instanceof Error) ? ex :
611	<	new RuntimeException(ex));
609	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
610	>	(ex instanceof Error) ? ex :
611	>	new RuntimeException(ex));
612		}
613
614		/**
#	Line 753 | Line 617 | public abstract class ForkJoinTask<V> im
617		* operations. This method may be used to provide results for
618		* asynchronous tasks, or to provide alternative handling for
619		* tasks that would not otherwise complete normally. Its use in
620	<	* other situations is likely to be wrong. This method is
620	>	* other situations is discouraged. This method is
621		* overridable, but overridden versions must invoke {@code super}
622		* implementation to maintain guarantees.
623		*
#	Line 763 | Line 627 | public abstract class ForkJoinTask<V> im
627		try {
628		setRawResult(value);
629		} catch (Throwable rex) {
630	<	setDoneExceptionally(rex);
630	>	setExceptionalCompletion(rex);
631		return;
632		}
633	<	setNormalCompletion();
633	>	setCompletion(NORMAL);
634		}
635
636		public final V get() throws InterruptedException, ExecutionException {
637	<	ForkJoinWorkerThread w = getWorker();
638	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
639	<	awaitDone(w, true);
640	<	return reportFutureResult();
637	>	quietlyJoin();
638	>	if (Thread.interrupted())
639	>	throw new InterruptedException();
640	>	int s = status;
641	>	if (s < NORMAL) {
642	>	Throwable ex;
643	>	if (s == CANCELLED)
644	>	throw new CancellationException();
645	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
646	>	throw new ExecutionException(ex);
647	>	}
648	>	return getRawResult();
649		}
650
651		public final V get(long timeout, TimeUnit unit)
652		throws InterruptedException, ExecutionException, TimeoutException {
653	<	ForkJoinWorkerThread w = getWorker();
654	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
655	<	awaitDone(w, unit.toNanos(timeout));
656	<	return reportTimedFutureResult();
657	<	}
658	<
659	<	/**
660	<	* Possibly executes other tasks until this task is ready, then
661	<	* returns the result of the computation.  This method may be more
662	<	* efficient than {@code join}, but is only applicable when
663	<	* there are no potential dependencies between continuation of the
664	<	* current task and that of any other task that might be executed
665	<	* while helping. (This usually holds for pure divide-and-conquer
666	<	* tasks). This method may be invoked only from within
667	<	* ForkJoinTask computations (as may be determined using method
668	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
669	<	* result in exceptions or errors, possibly including
670	<	* ClassCastException.
671	<	*
672	<	* @return the computed result
673	<	*/
674	<	public final V helpJoin() {
675	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
676	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
677	<	reportException(busyJoin(w));
678	<	return getRawResult();
679	<	}
680	<
681	<	/**
682	<	* Possibly executes other tasks until this task is ready.  This
683	<	* method may be invoked only from within ForkJoinTask
684	<	* computations (as may be determined using method {@link
685	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
686	<	* in exceptions or errors, possibly including ClassCastException.
687	<	*/
688	<	public final void quietlyHelpJoin() {
689	<	if (status >= 0) {
690	<	ForkJoinWorkerThread w =
691	<	(ForkJoinWorkerThread) Thread.currentThread();
692	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
693	<	busyJoin(w);
653	>	Thread t = Thread.currentThread();
654	>	ForkJoinPool pool;
655	>	if (t instanceof ForkJoinWorkerThread) {
656	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
657	>	if (status >= 0 && w.unpushTask(this))
658	>	quietlyExec();
659	>	pool = w.pool;
660	>	}
661	>	else
662	>	pool = null;
663	>	/*
664	>	* Timed wait loop intermixes cases for FJ (pool != null) and
665	>	* non FJ threads. For FJ, decrement pool count but don't try
666	>	* for replacement; increment count on completion. For non-FJ,
667	>	* deal with interrupts. This is messy, but a little less so
668	>	* than is splitting the FJ and nonFJ cases.
669	>	*/
670	>	boolean interrupted = false;
671	>	boolean dec = false; // true if pool count decremented
672	>	long nanos = unit.toNanos(timeout);
673	>	for (;;) {
674	>	if (Thread.interrupted() && pool == null) {
675	>	interrupted = true;
676	>	break;
677	>	}
678	>	int s = status;
679	>	if (s < 0)
680	>	break;
681	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
682	>	long startTime = System.nanoTime();
683	>	long nt; // wait time
684	>	while (status >= 0 &&
685	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
686	>	if (pool != null && !dec)
687	>	dec = pool.tryDecrementRunningCount();
688	>	else {
689	>	long ms = nt / 1000000;
690	>	int ns = (int) (nt % 1000000);
691	>	try {
692	>	synchronized(this) {
693	>	if (status >= 0)
694	>	wait(ms, ns);
695	>	}
696	>	} catch (InterruptedException ie) {
697	>	if (pool != null)
698	>	cancelIfTerminating();
699	>	else {
700	>	interrupted = true;
701	>	break;
702	>	}
703	>	}
704	>	}
705	>	}
706	>	break;
707	>	}
708		}
709	+	if (pool != null && dec)
710	+	pool.incrementRunningCount();
711	+	if (interrupted)
712	+	throw new InterruptedException();
713	+	int es = status;
714	+	if (es != NORMAL) {
715	+	Throwable ex;
716	+	if (es == CANCELLED)
717	+	throw new CancellationException();
718	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
719	+	throw new ExecutionException(ex);
720	+	throw new TimeoutException();
721	+	}
722	+	return getRawResult();
723		}
724
725		/**
726	<	* Joins this task, without returning its result or throwing an
726	>	* Joins this task, without returning its result or throwing its
727		* exception. This method may be useful when processing
728		* collections of tasks when some have been cancelled or otherwise
729		* known to have aborted.
730		*/
731		public final void quietlyJoin() {
732	<	if (status >= 0) {
733	<	ForkJoinWorkerThread w = getWorker();
734	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
735	<	awaitDone(w, true);
732	>	Thread t;
733	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
734	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
735	>	if (status >= 0) {
736	>	if (w.unpushTask(this)) {
737	>	boolean completed;
738	>	try {
739	>	completed = exec();
740	>	} catch (Throwable rex) {
741	>	setExceptionalCompletion(rex);
742	>	return;
743	>	}
744	>	if (completed) {
745	>	setCompletion(NORMAL);
746	>	return;
747	>	}
748	>	}
749	>	w.joinTask(this);
750	>	}
751		}
752	+	else
753	+	externalAwaitDone();
754		}
755
756		/**
757		* Commences performing this task and awaits its completion if
758	<	* necessary, without returning its result or throwing an
758	>	* necessary, without returning its result or throwing its
759		* exception. This method may be useful when processing
760		* collections of tasks when some have been cancelled or otherwise
761		* known to have aborted.
762		*/
763		public final void quietlyInvoke() {
764	<	if (status >= 0 && !tryQuietlyInvoke())
765	<	quietlyJoin();
764	>	if (status >= 0) {
765	>	boolean completed;
766	>	try {
767	>	completed = exec();
768	>	} catch (Throwable rex) {
769	>	setExceptionalCompletion(rex);
770	>	return;
771	>	}
772	>	if (completed)
773	>	setCompletion(NORMAL);
774	>	else
775	>	quietlyJoin();
776	>	}
777		}
778
779		/**
780		* Possibly executes tasks until the pool hosting the current task
781	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
782	<	* designs in which many tasks are forked, but none are explicitly
783	<	* joined, instead executing them until all are processed.
781	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
782	>	* be of use in designs in which many tasks are forked, but none
783	>	* are explicitly joined, instead executing them until all are
784	>	* processed.
785	>	*
786	>	* <p>This method may be invoked only from within {@code
787	>	* ForkJoinTask} computations (as may be determined using method
788	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
789	>	* result in exceptions or errors, possibly including {@code
790	>	* ClassCastException}.
791		*/
792		public static void helpQuiesce() {
793		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 865 | Line 800 | public abstract class ForkJoinTask<V> im
800		* this task, but only if reuse occurs when this task has either
801		* never been forked, or has been forked, then completed and all
802		* outstanding joins of this task have also completed. Effects
803	<	* under any other usage conditions are not guaranteed, and are
804	<	* almost surely wrong. This method may be useful when executing
803	>	* under any other usage conditions are not guaranteed.
804	>	* This method may be useful when executing
805		* pre-constructed trees of subtasks in loops.
806		*/
807		public void reinitialize() {
808	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
808	>	if (status == EXCEPTIONAL)
809		exceptionMap.remove(this);
810		status = 0;
811		}
#	Line 879 | Line 814 | public abstract class ForkJoinTask<V> im
814		* Returns the pool hosting the current task execution, or null
815		* if this task is executing outside of any ForkJoinPool.
816		*
817	<	* @return the pool, or null if none
817	>	* @see #inForkJoinPool
818	>	* @return the pool, or {@code null} if none
819		*/
820		public static ForkJoinPool getPool() {
821		Thread t = Thread.currentThread();
#	Line 904 | Line 840 | public abstract class ForkJoinTask<V> im
840		* by the current thread, and has not commenced executing in
841		* another thread.  This method may be useful when arranging
842		* alternative local processing of tasks that could have been, but
843	<	* were not, stolen. This method may be invoked only from within
908	<	* ForkJoinTask computations (as may be determined using method
909	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
910	<	* result in exceptions or errors, possibly including
911	<	* ClassCastException.
843	>	* were not, stolen.
844		*
845	<	* @return true if unforked
845	>	* <p>This method may be invoked only from within {@code
846	>	* ForkJoinTask} computations (as may be determined using method
847	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
848	>	* result in exceptions or errors, possibly including {@code
849	>	* ClassCastException}.
850	>	*
851	>	* @return {@code true} if unforked
852		*/
853		public boolean tryUnfork() {
854		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 923 | Line 861 | public abstract class ForkJoinTask<V> im
861		* value may be useful for heuristic decisions about whether to
862		* fork other tasks.
863		*
864	+	* <p>This method may be invoked only from within {@code
865	+	* ForkJoinTask} computations (as may be determined using method
866	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
867	+	* result in exceptions or errors, possibly including {@code
868	+	* ClassCastException}.
869	+	*
870		* @return the number of tasks
871		*/
872		public static int getQueuedTaskCount() {
#	Line 940 | Line 884 | public abstract class ForkJoinTask<V> im
884		* tasks, and to process computations locally if this threshold is
885		* exceeded.
886		*
887	+	* <p>This method may be invoked only from within {@code
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 {@code
891	+	* ClassCastException}.
892	+	*
893		* @return the surplus number of tasks, which may be negative
894		*/
895		public static int getSurplusQueuedTaskCount() {
#	Line 950 | Line 900 | public abstract class ForkJoinTask<V> im
900		// Extension methods
901
902		/**
903	<	* Returns the result that would be returned by {@code join},
904	<	* even if this task completed abnormally, or null if this task is
905	<	* not known to have been completed.  This method is designed to
906	<	* aid debugging, as well as to support extensions. Its use in any
907	<	* other context is discouraged.
903	>	* Returns the result that would be returned by {@link #join}, even
904	>	* if this task completed abnormally, or {@code null} if this task
905	>	* is not known to have been completed.  This method is designed
906	>	* to aid debugging, as well as to support extensions. Its use in
907	>	* any other context is discouraged.
908		*
909	<	* @return the result, or null if not completed
909	>	* @return the result, or {@code null} if not completed
910		*/
911		public abstract V getRawResult();
912
#	Line 975 | Line 925 | public abstract class ForkJoinTask<V> im
925		* called otherwise. The return value controls whether this task
926		* is considered to be done normally. It may return false in
927		* asynchronous actions that require explicit invocations of
928	<	* {@code complete} to become joinable. It may throw exceptions
929	<	* to indicate abnormal exit.
928	>	* {@link #complete} to become joinable. It may also throw an
929	>	* (unchecked) exception to indicate abnormal exit.
930		*
931	<	* @return true if completed normally
982	<	* @throws Error or RuntimeException if encountered during computation
931	>	* @return {@code true} if completed normally
932		*/
933		protected abstract boolean exec();
934
935		/**
936	<	* Returns, but does not unschedule or execute, the task queued by
937	<	* the current thread but not yet executed, if one is
936	>	* Returns, but does not unschedule or execute, a task queued by
937	>	* the current thread but not yet executed, if one is immediately
938		* available. There is no guarantee that this task will actually
939	<	* be polled or executed next.  This method is designed primarily
940	<	* to support extensions, and is unlikely to be useful otherwise.
941	<	* This method may be invoked only from within ForkJoinTask
942	<	* computations (as may be determined using method {@link
943	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
995	<	* in exceptions or errors, possibly including ClassCastException.
939	>	* be polled or executed next. Conversely, this method may return
940	>	* null even if a task exists but cannot be accessed without
941	>	* contention with other threads.  This method is designed
942	>	* primarily to support extensions, and is unlikely to be useful
943	>	* otherwise.
944		*
945	<	* @return the next task, or null if none are available
945	>	* <p>This method may be invoked only from within {@code
946	>	* ForkJoinTask} computations (as may be determined using method
947	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
948	>	* result in exceptions or errors, possibly including {@code
949	>	* ClassCastException}.
950	>	*
951	>	* @return the next task, or {@code null} if none are available
952		*/
953		protected static ForkJoinTask<?> peekNextLocalTask() {
954		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 1005 | Line 959 | public abstract class ForkJoinTask<V> im
959		* Unschedules and returns, without executing, the next task
960		* queued by the current thread but not yet executed.  This method
961		* is designed primarily to support extensions, and is unlikely to
962	<	* be useful otherwise.  This method may be invoked only from
963	<	* within ForkJoinTask computations (as may be determined using
964	<	* method {@link #inForkJoinPool}). Attempts to invoke in other
965	<	* contexts result in exceptions or errors, possibly including
966	<	* ClassCastException.
962	>	* be useful otherwise.
963	>	*
964	>	* <p>This method may be invoked only from within {@code
965	>	* ForkJoinTask} computations (as may be determined using method
966	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
967	>	* result in exceptions or errors, possibly including {@code
968	>	* ClassCastException}.
969		*
970	<	* @return the next task, or null if none are available
970	>	* @return the next task, or {@code null} if none are available
971		*/
972		protected static ForkJoinTask<?> pollNextLocalTask() {
973		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 1026 | Line 982 | public abstract class ForkJoinTask<V> im
982		* {@code null} result does not necessarily imply quiescence
983		* of the pool this task is operating in.  This method is designed
984		* primarily to support extensions, and is unlikely to be useful
985	<	* otherwise.  This method may be invoked only from within
1030	<	* ForkJoinTask computations (as may be determined using method
1031	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1032	<	* result in exceptions or errors, possibly including
1033	<	* ClassCastException.
985	>	* otherwise.
986		*
987	<	* @return a task, or null if none are available
987	>	* <p>This method may be invoked only from within {@code
988	>	* ForkJoinTask} computations (as may be determined using method
989	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
990	>	* result in exceptions or errors, possibly including {@code
991	>	* ClassCastException}.
992	>	*
993	>	* @return a task, or {@code null} if none are available
994		*/
995		protected static ForkJoinTask<?> pollTask() {
996		return ((ForkJoinWorkerThread) Thread.currentThread())
997		.pollTask();
998		}
999
1000	<	// adaptors
1000	>	/**
1001	>	* Adaptor for Runnables. This implements RunnableFuture
1002	>	* to be compliant with AbstractExecutorService constraints
1003	>	* when used in ForkJoinPool.
1004	>	*/
1005	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1006	>	implements RunnableFuture<T> {
1007	>	final Runnable runnable;
1008	>	final T resultOnCompletion;
1009	>	T result;
1010	>	AdaptedRunnable(Runnable runnable, T result) {
1011	>	if (runnable == null) throw new NullPointerException();
1012	>	this.runnable = runnable;
1013	>	this.resultOnCompletion = result;
1014	>	}
1015	>	public T getRawResult() { return result; }
1016	>	public void setRawResult(T v) { result = v; }
1017	>	public boolean exec() {
1018	>	runnable.run();
1019	>	result = resultOnCompletion;
1020	>	return true;
1021	>	}
1022	>	public void run() { invoke(); }
1023	>	private static final long serialVersionUID = 5232453952276885070L;
1024	>	}
1025
1026		/**
1027	<	* Returns a new ForkJoinTask that performs the <code>run</code>
1028	<	* method of the given Runnable as its action, and returns a null
1029	<	* result upon <code>join</code>.
1027	>	* Adaptor for Callables
1028	>	*/
1029	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1030	>	implements RunnableFuture<T> {
1031	>	final Callable<? extends T> callable;
1032	>	T result;
1033	>	AdaptedCallable(Callable<? extends T> callable) {
1034	>	if (callable == null) throw new NullPointerException();
1035	>	this.callable = callable;
1036	>	}
1037	>	public T getRawResult() { return result; }
1038	>	public void setRawResult(T v) { result = v; }
1039	>	public boolean exec() {
1040	>	try {
1041	>	result = callable.call();
1042	>	return true;
1043	>	} catch (Error err) {
1044	>	throw err;
1045	>	} catch (RuntimeException rex) {
1046	>	throw rex;
1047	>	} catch (Exception ex) {
1048	>	throw new RuntimeException(ex);
1049	>	}
1050	>	}
1051	>	public void run() { invoke(); }
1052	>	private static final long serialVersionUID = 2838392045355241008L;
1053	>	}
1054	>
1055	>	/**
1056	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1057	>	* method of the given {@code Runnable} as its action, and returns
1058	>	* a null result upon {@link #join}.
1059		*
1060		* @param runnable the runnable action
1061		* @return the task
1062		*/
1063	<	public static ForkJoinTask<Void> adapt(Runnable runnable) {
1064	<	return new ForkJoinPool.AdaptedRunnable<Void>(runnable, null);
1063	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1064	>	return new AdaptedRunnable<Void>(runnable, null);
1065		}
1066
1067		/**
1068	<	* Returns a new ForkJoinTask that performs the <code>run</code>
1069	<	* method of the given Runnable as its action, and returns the
1070	<	* given result upon <code>join</code>.
1068	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1069	>	* method of the given {@code Runnable} as its action, and returns
1070	>	* the given result upon {@link #join}.
1071		*
1072		* @param runnable the runnable action
1073		* @param result the result upon completion
1074		* @return the task
1075		*/
1076		public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1077	<	return new ForkJoinPool.AdaptedRunnable<T>(runnable, result);
1077	>	return new AdaptedRunnable<T>(runnable, result);
1078		}
1079
1080		/**
1081	<	* Returns a new ForkJoinTask that performs the <code>call</code>
1082	<	* method of the given Callable as its action, and returns its
1083	<	* result upon <code>join</code>, translating any checked
1084	<	* exceptions encountered into <code>RuntimeException<code>.
1081	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1082	>	* method of the given {@code Callable} as its action, and returns
1083	>	* its result upon {@link #join}, translating any checked exceptions
1084	>	* encountered into {@code RuntimeException}.
1085		*
1086		* @param callable the callable action
1087		* @return the task
1088		*/
1089	<	public static <T> ForkJoinTask<T> adapt(Callable<T> callable) {
1090	<	return new ForkJoinPool.AdaptedCallable<T>(callable);
1089	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1090	>	return new AdaptedCallable<T>(callable);
1091		}
1092
1093		// Serialization support
#	Line 1084 | Line 1095 | public abstract class ForkJoinTask<V> im
1095		private static final long serialVersionUID = -7721805057305804111L;
1096
1097		/**
1098	<	* Save the state to a stream.
1098	>	* Saves the state to a stream (that is, serializes it).
1099		*
1100		* @serialData the current run status and the exception thrown
1101	<	* during execution, or null if none
1101	>	* during execution, or {@code null} if none
1102		* @param s the stream
1103		*/
1104		private void writeObject(java.io.ObjectOutputStream s)
#	Line 1097 | Line 1108 | public abstract class ForkJoinTask<V> im
1108		}
1109
1110		/**
1111	<	* Reconstitute the instance from a stream.
1111	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1112		*
1113		* @param s the stream
1114		*/
1115		private void readObject(java.io.ObjectInputStream s)
1116		throws java.io.IOException, ClassNotFoundException {
1117		s.defaultReadObject();
1107	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1108	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1118		Object ex = s.readObject();
1119		if (ex != null)
1120	<	setDoneExceptionally((Throwable) ex);
1120	>	setExceptionalCompletion((Throwable) ex);
1121	>	}
1122	>
1123	>	// Unsafe mechanics
1124	>
1125	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1126	>	private static final long statusOffset =
1127	>	objectFieldOffset("status", ForkJoinTask.class);
1128	>
1129	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1130	>	try {
1131	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1132	>	} catch (NoSuchFieldException e) {
1133	>	// Convert Exception to corresponding Error
1134	>	NoSuchFieldError error = new NoSuchFieldError(field);
1135	>	error.initCause(e);
1136	>	throw error;
1137	>	}
1138		}
1139
1140	<	// Unsafe mechanics for jsr166y 3rd party package.
1140	>	/**
1141	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1142	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1143	>	* into a jdk.
1144	>	*
1145	>	* @return a sun.misc.Unsafe
1146	>	*/
1147		private static sun.misc.Unsafe getUnsafe() {
1148		try {
1149		return sun.misc.Unsafe.getUnsafe();
1150		} catch (SecurityException se) {
1151		try {
1152		return java.security.AccessController.doPrivileged
1153	<	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1153	>	(new java.security
1154	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1155		public sun.misc.Unsafe run() throws Exception {
1156	<	return getUnsafeByReflection();
1156	>	java.lang.reflect.Field f = sun.misc
1157	>	.Unsafe.class.getDeclaredField("theUnsafe");
1158	>	f.setAccessible(true);
1159	>	return (sun.misc.Unsafe) f.get(null);
1160		}});
1161		} catch (java.security.PrivilegedActionException e) {
1162		throw new RuntimeException("Could not initialize intrinsics",
#	Line 1128 | Line 1164 | public abstract class ForkJoinTask<V> im
1164		}
1165		}
1166		}
1131	–
1132	–	private static sun.misc.Unsafe getUnsafeByReflection()
1133	–	throws NoSuchFieldException, IllegalAccessException {
1134	–	java.lang.reflect.Field f =
1135	–	sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
1136	–	f.setAccessible(true);
1137	–	return (sun.misc.Unsafe) f.get(null);
1138	–	}
1139	–
1140	–	private static long fieldOffset(String fieldName, Class<?> klazz) {
1141	–	try {
1142	–	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName));
1143	–	} catch (NoSuchFieldException e) {
1144	–	// Convert Exception to Error
1145	–	NoSuchFieldError error = new NoSuchFieldError(fieldName);
1146	–	error.initCause(e);
1147	–	throw error;
1148	–	}
1149	–	}
1150	–
1151	–	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1152	–	private static final long statusOffset =
1153	–	fieldOffset("status", ForkJoinTask.class);
1154	–
1167		}

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