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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.21 by jsr166, Sun Jul 26 06:26:37 2009 UTC vs.
Revision 1.49 by dl, Wed Jul 7 19:52:31 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	+	* 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.
148	+	*/
149	+
150		/**
151		* Run control status bits packed into a single int to minimize
152		* footprint and to ensure atomicity (via CAS).  Status is
153		* initially zero, and takes on nonnegative values until
154	<	* completed, upon which status holds COMPLETED. CANCELLED, or
155	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
156	<	* blocking waits by other threads have SIGNAL_MASK bits set --
157	<	* bit 15 for external (nonFJ) waits, and the rest a count of
158	<	* waiting FJ threads.  (This representation relies on
159	<	* ForkJoinPool max thread limits). Completion of a stolen task
160	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
161	<	* though suboptimal for some purposes, we use basic builtin
162	<	* wait/notify to take advantage of "monitor inflation" in JVMs
163	<	* that we would otherwise need to emulate to avoid adding further
135	<	* per-task bookkeeping overhead. Note that bits 16-28 are
136	<	* currently unused. Also value 0x80000000 is available as spare
137	<	* completion value.
154	>	* completed, upon which status holds value COMPLETED. CANCELLED,
155	>	* or EXCEPTIONAL. Tasks undergoing blocking waits by other
156	>	* threads have the SIGNAL bit set.  Completion of a stolen task
157	>	* with SIGNAL set awakens any waiters via notifyAll. Even though
158	>	* suboptimal for some purposes, we use basic builtin wait/notify
159	>	* to take advantage of "monitor inflation" in JVMs that we would
160	>	* otherwise need to emulate to avoid adding further per-task
161	>	* bookkeeping overhead.  We want these monitors to be "fat",
162	>	* i.e., not use biasing or thin-lock techniques, so use some odd
163	>	* coding idioms that tend to avoid them.
164		*/
165		volatile int status; // accessed directly by pool and workers
166
167	<	static final int COMPLETION_MASK      = 0xe0000000;
168	<	static final int NORMAL               = 0xe0000000; // == mask
169	<	static final int CANCELLED            = 0xc0000000;
170	<	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
167	>	private static final int NORMAL      = -1;
168	>	private static final int CANCELLED   = -2;
169	>	private static final int EXCEPTIONAL = -3;
170	>	private static final int SIGNAL      =  1;
171
172		/**
173		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 158 | Line 181 | public abstract class ForkJoinTask<V> im
181		Collections.synchronizedMap
182		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
183
184	<	// 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
184	>	// Maintaining completion status
185
186		/**
187	<	* Marks completion and wakes up threads waiting to join this task.
187	>	* Marks completion and wakes up threads waiting to join this task,
188	>	* also clearing signal request bits.
189		*
190		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
191	+	* @return status on exit
192		*/
193	<	final void setCompletion(int completion) {
192	<	ForkJoinPool pool = getPool();
193	<	if (pool != null) {
194	<	int s; // Clear signal bits while setting completion status
195	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
196	<
197	<	if ((s & SIGNAL_MASK) != 0) {
198	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
199	<	pool.updateRunningCount(s);
200	<	synchronized (this) { notifyAll(); }
201	<	}
202	<	}
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) {
193	>	private int setCompletion(int completion) {
194		int s;
195	<	do {} while ((s = status) >= 0 &&
196	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
197	<	synchronized (this) { notifyAll(); }
198	<	}
199	<
218	<	/**
219	<	* Sets status to indicate normal completion.
220	<	*/
221	<	final void setNormalCompletion() {
222	<	// Try typical fast case -- single CAS, no signal, not already done.
223	<	// 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	<	}
242	<	}
243	<
244	<	/**
245	<	* Performs the actual timed monitor wait for awaitDone.
246	<	*/
247	<	private void doAwaitDone(long startTime, long nanos) {
248	<	synchronized (this) {
249	<	try {
250	<	while (status >= 0) {
251	<	long nt = nanos - System.nanoTime() - startTime;
252	<	if (nt <= 0)
253	<	break;
254	<	wait(nt / 1000000, (int) (nt % 1000000));
255	<	}
256	<	} catch (InterruptedException ie) {
257	<	onInterruptedWait();
195	>	while ((s = status) >= 0) {
196	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
197	>	if (s == SIGNAL)
198	>	synchronized (this) { notifyAll(); }
199	>	return completion;
200		}
201		}
202	+	return s;
203		}
204
262	–	// Awaiting completion
263	–
205		/**
206	<	* Sets status to indicate there is joiner, then waits for join,
207	<	* surrounded with pool notifications.
267	<	*
268	<	* @return status upon exit
206	>	* Record exception and set exceptional completion
207	>	* @return status on exit
208		*/
209	<	private int awaitDone(ForkJoinWorkerThread w,
210	<	boolean maintainParallelism) {
211	<	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;
281	<	}
282	<	}
283	<	return s;
209	>	private int setExceptionalCompletion(Throwable rex) {
210	>	exceptionMap.put(this, rex);
211	>	return setCompletion(EXCEPTIONAL);
212		}
213
214		/**
215	<	* Timed version of awaitDone
288	<	*
289	<	* @return status upon exit
215	>	* Blocks a worker thread until completion. Called only by pool.
216		*/
217	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
292	<	ForkJoinPool pool = (w == null) ? null : w.pool;
217	>	final int internalAwaitDone() {
218		int s;
219		while ((s = status) >= 0) {
220	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
221	<	long startTime = System.nanoTime();
222	<	if (pool == null || !pool.preJoin(this, false))
223	<	doAwaitDone(startTime, nanos);
224	<	if ((s = status) >= 0) {
225	<	adjustPoolCountsOnCancelledWait(pool);
226	<	s = status;
220	>	synchronized(this) {
221	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
222	>	do {
223	>	try {
224	>	wait();
225	>	} catch (InterruptedException ie) {
226	>	cancelIfTerminating();
227	>	}
228	>	} while ((s = status) >= 0);
229	>	break;
230		}
303	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
304	–	adjustPoolCountsOnUnblock(pool);
305	–	break;
231		}
232		}
233		return s;
234		}
235
236		/**
237	<	* Notifies pool that thread is unblocked. Called by signalled
238	<	* threads when woken by non-FJ threads (which is atypical).
237	>	* Blocks a non-worker-thread until completion.
238	>	* @return status on exit
239		*/
240	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
240	>	private int externalAwaitDone() {
241		int s;
242	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
243	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
244	<	pool.updateRunningCount(s);
245	<	}
246	<
247	<	/**
248	<	* Notifies pool to adjust counts on cancelled or timed out wait.
249	<	*/
250	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
251	<	if (pool != null) {
252	<	int s;
253	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
254	<	if (casStatus(s, s - 1)) {
330	<	pool.updateRunningCount(1);
242	>	while ((s = status) >= 0) {
243	>	synchronized(this) {
244	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
245	>	boolean interrupted = false;
246	>	do {
247	>	try {
248	>	wait();
249	>	} catch (InterruptedException ie) {
250	>	interrupted = true;
251	>	}
252	>	} while ((s = status) >= 0);
253	>	if (interrupted)
254	>	Thread.currentThread().interrupt();
255		break;
256		}
257		}
258		}
259	+	return s;
260		}
261
262		/**
263	<	* Handles interruptions during waits.
264	<	*/
265	<	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.
263	>	* Unless done, calls exec and records status if completed, but
264	>	* doesn't wait for completion otherwise. Primary execution method
265	>	* for ForkJoinWorkerThread.
266		*/
267	<	private V reportFutureResult()
268	<	throws ExecutionException, InterruptedException {
269	<	int s = status & COMPLETION_MASK;
270	<	if (s < NORMAL) {
271	<	Throwable ex;
272	<	if (s == CANCELLED)
273	<	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();
267	>	final void tryExec() {
268	>	try {
269	>	if (status < 0 || !exec())
270	>	return;
271	>	} catch (Throwable rex) {
272	>	setExceptionalCompletion(rex);
273	>	return;
274		}
275	<	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();
275	>	setCompletion(NORMAL); // must be outside try block
276		}
277
408	–	// internal execution methods
409	–
278		/**
279	<	* Calls exec, recording completion, and rethrowing exception if
280	<	* encountered. Caller should normally check status before calling.
281	<	*
414	<	* @return true if completed normally
279	>	* If not done and this task is next in worker queue, runs it,
280	>	* else waits for it.
281	>	* @return status on exit
282		*/
283	<	private boolean tryExec() {
284	<	try { // try block must contain only call to exec
285	<	if (!exec())
286	<	return false;
287	<	} catch (Throwable rex) {
288	<	setDoneExceptionally(rex);
289	<	rethrowException(rex);
290	<	return false; // not reached
283	>	private int doJoin() {
284	>	int stat;
285	>	if ((stat = status) < 0)
286	>	return stat;
287	>	Thread t = Thread.currentThread();
288	>	ForkJoinWorkerThread w;
289	>	if (t instanceof ForkJoinWorkerThread) {
290	>	if ((w = (ForkJoinWorkerThread) t).unpushTask(this)) {
291	>	boolean completed;
292	>	try {
293	>	completed = exec();
294	>	} catch (Throwable rex) {
295	>	return setExceptionalCompletion(rex);
296	>	}
297	>	if (completed)
298	>	return setCompletion(NORMAL);
299	>	}
300	>	w.joinTask(this);
301	>	return status;
302		}
303	<	setNormalCompletion();
426	<	return true;
303	>	return externalAwaitDone();
304		}
305
306		/**
307	<	* Main execution method used by worker threads. Invokes
308	<	* base computation unless already complete.
307	>	* Unless done, calls exec and records status if completed, or
308	>	* waits for completion otherwise.
309	>	* @return status on exit
310		*/
311	<	final void quietlyExec() {
312	<	if (status >= 0) {
311	>	private int doInvoke() {
312	>	int stat;
313	>	if ((stat = status) >= 0) {
314	>	boolean completed;
315		try {
316	<	if (!exec())
437	<	return;
316	>	completed = exec();
317		} catch (Throwable rex) {
318	<	setDoneExceptionally(rex);
440	<	return;
318	>	return setExceptionalCompletion(rex);
319		}
320	<	setNormalCompletion();
321	<	}
322	<	}
323	<
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() {
453	<	try {
454	<	if (!exec())
455	<	return false;
456	<	} catch (Throwable rex) {
457	<	setDoneExceptionally(rex);
458	<	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) {
320	>	if (completed)
321	>	stat = setCompletion(NORMAL);
322	>	else
323	>	stat = doJoin();
324		}
325	+	return stat;
326		}
327
328		/**
329	<	* Main implementation of helpJoin
329	>	* Returns result or throws exception associated with given status.
330	>	* @param s the status
331		*/
332	<	private int busyJoin(ForkJoinWorkerThread w) {
333	<	int s;
334	<	ForkJoinTask<?> t;
335	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
336	<	t.quietlyExec();
482	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
332	>	private V reportResult(int s) {
333	>	Throwable ex;
334	>	if (s < NORMAL && (ex = getException()) != null)
335	>	UNSAFE.throwException(ex);
336	>	return getRawResult();
337		}
338
339		// public methods
#	Line 487 | Line 341 | public abstract class ForkJoinTask<V> im
341		/**
342		* Arranges to asynchronously execute this task.  While it is not
343		* necessarily enforced, it is a usage error to fork a task more
344	<	* than once unless it has completed and been reinitialized.  This
345	<	* method may be invoked only from within ForkJoinTask
346	<	* computations (as may be determined using method {@link
347	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
348	<	* in exceptions or errors, possibly including ClassCastException.
344	>	* than once unless it has completed and been reinitialized.
345	>	* Subsequent modifications to the state of this task or any data
346	>	* it operates on are not necessarily consistently observable by
347	>	* any thread other than the one executing it unless preceded by a
348	>	* call to {@link #join} or related methods, or a call to {@link
349	>	* #isDone} returning {@code true}.
350	>	*
351	>	* <p>This method may be invoked only from within {@code
352	>	* ForkJoinTask} computations (as may be determined using method
353	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
354	>	* result in exceptions or errors, possibly including {@code
355	>	* ClassCastException}.
356		*
357	<	* @return {@code this}, to simplify usage.
357	>	* @return {@code this}, to simplify usage
358		*/
359		public final ForkJoinTask<V> fork() {
360		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 502 | Line 363 | public abstract class ForkJoinTask<V> im
363		}
364
365		/**
366	<	* Returns the result of the computation when it is ready.
367	<	* This method differs from {@code get} in that abnormal
368	<	* completion results in RuntimeExceptions or Errors, not
369	<	* ExecutionExceptions.
366	>	* Returns the result of the computation when it {@link #isDone is done}.
367	>	* This method differs from {@link #get()} in that
368	>	* abnormal completion results in {@code RuntimeException} or
369	>	* {@code Error}, not {@code ExecutionException}.
370		*
371		* @return the computed result
372		*/
373		public final V join() {
374	<	ForkJoinWorkerThread w = getWorker();
514	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
515	<	reportException(awaitDone(w, true));
516	<	return getRawResult();
374	>	return reportResult(doJoin());
375		}
376
377		/**
378		* Commences performing this task, awaits its completion if
379	<	* necessary, and return its result.
379	>	* necessary, and return its result, or throws an (unchecked)
380	>	* exception if the underlying computation did so.
381		*
523	–	* @throws Throwable (a RuntimeException, Error, or unchecked
524	–	* exception) if the underlying computation did so
382		* @return the computed result
383		*/
384		public final V invoke() {
385	<	if (status >= 0 && tryExec())
529	<	return getRawResult();
530	<	else
531	<	return join();
385	>	return reportResult(doInvoke());
386		}
387
388		/**
389	<	* Forks both tasks, returning when {@code isDone} holds for
390	<	* both of them or an exception is encountered. This method may be
391	<	* invoked only from within ForkJoinTask computations (as may be
392	<	* determined using method {@link #inForkJoinPool}). Attempts to
393	<	* invoke in other contexts result in exceptions or errors,
394	<	* possibly including ClassCastException.
389	>	* Forks the given tasks, returning when {@code isDone} holds for
390	>	* each task or an (unchecked) exception is encountered, in which
391	>	* case the exception is rethrown.  If either task encounters an
392	>	* exception, the other one may be, but is not guaranteed to be,
393	>	* cancelled.  If both tasks throw an exception, then this method
394	>	* throws one of them.  The individual status of each task may be
395	>	* checked using {@link #getException()} and related methods.
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 t1 one task
404	<	* @param t2 the other task
405	<	* @throws NullPointerException if t1 or t2 are null
545	<	* @throws RuntimeException or Error if either task did so
403	>	* @param t1 the first task
404	>	* @param t2 the second task
405	>	* @throws NullPointerException if any task is null
406		*/
407	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
407	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
408		t2.fork();
409		t1.invoke();
410		t2.join();
411		}
412
413		/**
414	<	* Forks the given tasks, returning when {@code isDone} holds
415	<	* for all of them. If any task encounters an exception, others
416	<	* may be cancelled.  This method may be invoked only from within
417	<	* ForkJoinTask computations (as may be determined using method
418	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
419	<	* result in exceptions or errors, possibly including
420	<	* ClassCastException.
414	>	* Forks the given tasks, returning when {@code isDone} holds for
415	>	* each task or an (unchecked) exception is encountered, in which
416	>	* case the exception is rethrown. If any task encounters an
417	>	* exception, others may be, but are not guaranteed to be,
418	>	* cancelled.  If more than one task encounters an exception, then
419	>	* this method throws any one of these exceptions.  The individual
420	>	* status of each task may be checked using {@link #getException()}
421	>	* and related methods.
422	>	*
423	>	* <p>This method may be invoked only from within {@code
424	>	* ForkJoinTask} computations (as may be determined using method
425	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
426	>	* result in exceptions or errors, possibly including {@code
427	>	* ClassCastException}.
428		*
429	<	* @param tasks the array of tasks
430	<	* @throws NullPointerException if tasks or any element are null
564	<	* @throws RuntimeException or Error if any task did so
429	>	* @param tasks the tasks
430	>	* @throws NullPointerException if any task is null
431		*/
432		public static void invokeAll(ForkJoinTask<?>... tasks) {
433		Throwable ex = null;
#	Line 574 | Line 440 | public abstract class ForkJoinTask<V> im
440		}
441		else if (i != 0)
442		t.fork();
443	<	else {
444	<	t.quietlyInvoke();
579	<	if (ex == null)
580	<	ex = t.getException();
581	<	}
443	>	else if (t.doInvoke() < NORMAL && ex == null)
444	>	ex = t.getException();
445		}
446		for (int i = 1; i <= last; ++i) {
447		ForkJoinTask<?> t = tasks[i];
448		if (t != null) {
449		if (ex != null)
450		t.cancel(false);
451	<	else {
452	<	t.quietlyJoin();
590	<	if (ex == null)
591	<	ex = t.getException();
592	<	}
451	>	else if (t.doJoin() < NORMAL && ex == null)
452	>	ex = t.getException();
453		}
454		}
455		if (ex != null)
456	<	rethrowException(ex);
456	>	UNSAFE.throwException(ex);
457		}
458
459		/**
460	<	* Forks all tasks in the collection, returning when
461	<	* {@code isDone} holds for all of them. If any task
462	<	* encounters an exception, others may be cancelled.  This method
463	<	* may be invoked only from within ForkJoinTask computations (as
464	<	* may be determined using method {@link
465	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
466	<	* in exceptions or errors, possibly including ClassCastException.
460	>	* Forks all tasks in the specified collection, returning when
461	>	* {@code isDone} holds for each task or an (unchecked) exception
462	>	* is encountered.  If any task encounters an exception, others
463	>	* may be, but are not guaranteed to be, cancelled.  If more than
464	>	* one task encounters an exception, then this method throws any
465	>	* one of these exceptions.  The individual status of each task
466	>	* may be checked using {@link #getException()} and related
467	>	* methods.  The behavior of this operation is undefined if the
468	>	* specified collection is modified while the operation is in
469	>	* progress.
470	>	*
471	>	* <p>This method may be invoked only from within {@code
472	>	* ForkJoinTask} computations (as may be determined using method
473	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
474	>	* result in exceptions or errors, possibly including {@code
475	>	* ClassCastException}.
476		*
477		* @param tasks the collection of tasks
478		* @return the tasks argument, to simplify usage
479		* @throws NullPointerException if tasks or any element are null
611	–	* @throws RuntimeException or Error if any task did so
480		*/
481		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
482	<	if (!(tasks instanceof List<?>)) {
482	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
483		invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
484		return tasks;
485		}
#	Line 628 | Line 496 | public abstract class ForkJoinTask<V> im
496		}
497		else if (i != 0)
498		t.fork();
499	<	else {
500	<	t.quietlyInvoke();
633	<	if (ex == null)
634	<	ex = t.getException();
635	<	}
499	>	else if (t.doInvoke() < NORMAL && ex == null)
500	>	ex = t.getException();
501		}
502		for (int i = 1; i <= last; ++i) {
503		ForkJoinTask<?> t = ts.get(i);
504		if (t != null) {
505		if (ex != null)
506		t.cancel(false);
507	<	else {
508	<	t.quietlyJoin();
644	<	if (ex == null)
645	<	ex = t.getException();
646	<	}
507	>	else if (t.doJoin() < NORMAL && ex == null)
508	>	ex = t.getException();
509		}
510		}
511		if (ex != null)
512	<	rethrowException(ex);
512	>	UNSAFE.throwException(ex);
513		return tasks;
514		}
515
516		/**
517	<	* Returns true if the computation performed by this task has
518	<	* completed (or has been cancelled).
519	<	*
520	<	* @return true if this computation has completed
521	<	*/
522	<	public final boolean isDone() {
523	<	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.
517	>	* Attempts to cancel execution of this task. This attempt will
518	>	* fail if the task has already completed, has already been
519	>	* cancelled, or could not be cancelled for some other reason. If
520	>	* successful, and this task has not started when cancel is
521	>	* called, execution of this task is suppressed, {@link
522	>	* #isCancelled} will report true, and {@link #join} will result
523	>	* in a {@code CancellationException} being thrown.
524		*
525		* <p>This method may be overridden in subclasses, but if so, must
526		* still ensure that these minimal properties hold. In particular,
527	<	* the cancel method itself must not throw exceptions.
527	>	* the {@code cancel} method itself must not throw exceptions.
528		*
529	<	* <p> This method is designed to be invoked by <em>other</em>
529	>	* <p>This method is designed to be invoked by <em>other</em>
530		* tasks. To terminate the current task, you can just return or
531		* throw an unchecked exception from its computation method, or
532	<	* invoke {@code completeExceptionally}.
532	>	* invoke {@link #completeExceptionally}.
533		*
534		* @param mayInterruptIfRunning this value is ignored in the
535	<	* default implementation because tasks are not in general
535	>	* default implementation because tasks are not
536		* cancelled via interruption
537		*
538	<	* @return true if this task is now cancelled
538	>	* @return {@code true} if this task is now cancelled
539		*/
540		public boolean cancel(boolean mayInterruptIfRunning) {
541		setCompletion(CANCELLED);
542	<	return (status & COMPLETION_MASK) == CANCELLED;
542	>	return status == CANCELLED;
543	>	}
544	>
545	>	/**
546	>	* Cancels, ignoring any exceptions it throws. Used during worker
547	>	* and pool shutdown.
548	>	*/
549	>	final void cancelIgnoringExceptions() {
550	>	try {
551	>	cancel(false);
552	>	} catch (Throwable ignore) {
553	>	}
554		}
555
556		/**
557	<	* Returns true if this task threw an exception or was cancelled.
557	>	* Cancels ignoring exceptions if worker is terminating
558	>	*/
559	>	private void cancelIfTerminating() {
560	>	Thread t = Thread.currentThread();
561	>	if ((t instanceof ForkJoinWorkerThread) &&
562	>	((ForkJoinWorkerThread) t).isTerminating()) {
563	>	try {
564	>	cancel(false);
565	>	} catch (Throwable ignore) {
566	>	}
567	>	}
568	>	}
569	>
570	>	public final boolean isDone() {
571	>	return status < 0;
572	>	}
573	>
574	>	public final boolean isCancelled() {
575	>	return status == CANCELLED;
576	>	}
577	>
578	>	/**
579	>	* Returns {@code true} if this task threw an exception or was cancelled.
580		*
581	<	* @return true if this task threw an exception or was cancelled
581	>	* @return {@code true} if this task threw an exception or was cancelled
582		*/
583		public final boolean isCompletedAbnormally() {
584	<	return (status & COMPLETION_MASK) < NORMAL;
584	>	return status < NORMAL;
585	>	}
586	>
587	>	/**
588	>	* Returns {@code true} if this task completed without throwing an
589	>	* exception and was not cancelled.
590	>	*
591	>	* @return {@code true} if this task completed without throwing an
592	>	* exception and was not cancelled
593	>	*/
594	>	public final boolean isCompletedNormally() {
595	>	return status == NORMAL;
596		}
597
598		/**
599		* Returns the exception thrown by the base computation, or a
600	<	* CancellationException if cancelled, or null if none or if the
601	<	* method has not yet completed.
600	>	* {@code CancellationException} if cancelled, or {@code null} if
601	>	* none or if the method has not yet completed.
602		*
603	<	* @return the exception, or null if none
603	>	* @return the exception, or {@code null} if none
604		*/
605		public final Throwable getException() {
606	<	int s = status & COMPLETION_MASK;
607	<	if (s >= NORMAL)
608	<	return null;
609	<	if (s == CANCELLED)
726	<	return new CancellationException();
727	<	return exceptionMap.get(this);
606	>	int s = status;
607	>	return ((s >= NORMAL)    ? null :
608	>	(s == CANCELLED) ? new CancellationException() :
609	>	exceptionMap.get(this));
610		}
611
612		/**
#	Line 733 | Line 615 | public abstract class ForkJoinTask<V> im
615		* {@code join} and related operations. This method may be used
616		* to induce exceptions in asynchronous tasks, or to force
617		* completion of tasks that would not otherwise complete.  Its use
618	<	* in other situations is likely to be wrong.  This method is
618	>	* in other situations is discouraged.  This method is
619		* overridable, but overridden versions must invoke {@code super}
620		* implementation to maintain guarantees.
621		*
622	<	* @param ex the exception to throw. If this exception is
623	<	* not a RuntimeException or Error, the actual exception thrown
624	<	* will be a RuntimeException with cause ex.
622	>	* @param ex the exception to throw. If this exception is not a
623	>	* {@code RuntimeException} or {@code Error}, the actual exception
624	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
625		*/
626		public void completeExceptionally(Throwable ex) {
627	<	setDoneExceptionally((ex instanceof RuntimeException) ||
628	<	(ex instanceof Error) ? ex :
629	<	new RuntimeException(ex));
627	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
628	>	(ex instanceof Error) ? ex :
629	>	new RuntimeException(ex));
630		}
631
632		/**
#	Line 753 | Line 635 | public abstract class ForkJoinTask<V> im
635		* operations. This method may be used to provide results for
636		* asynchronous tasks, or to provide alternative handling for
637		* tasks that would not otherwise complete normally. Its use in
638	<	* other situations is likely to be wrong. This method is
638	>	* other situations is discouraged. This method is
639		* overridable, but overridden versions must invoke {@code super}
640		* implementation to maintain guarantees.
641		*
#	Line 763 | Line 645 | public abstract class ForkJoinTask<V> im
645		try {
646		setRawResult(value);
647		} catch (Throwable rex) {
648	<	setDoneExceptionally(rex);
648	>	setExceptionalCompletion(rex);
649		return;
650		}
651	<	setNormalCompletion();
651	>	setCompletion(NORMAL);
652		}
653
654		public final V get() throws InterruptedException, ExecutionException {
655	<	ForkJoinWorkerThread w = getWorker();
656	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
657	<	awaitDone(w, true);
658	<	return reportFutureResult();
655	>	int s = doJoin();
656	>	if (Thread.interrupted())
657	>	throw new InterruptedException();
658	>	if (s < NORMAL) {
659	>	Throwable ex;
660	>	if (s == CANCELLED)
661	>	throw new CancellationException();
662	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
663	>	throw new ExecutionException(ex);
664	>	}
665	>	return getRawResult();
666		}
667
668		public final V get(long timeout, TimeUnit unit)
669		throws InterruptedException, ExecutionException, TimeoutException {
670	<	ForkJoinWorkerThread w = getWorker();
671	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
672	<	awaitDone(w, unit.toNanos(timeout));
673	<	return reportTimedFutureResult();
674	<	}
675	<
676	<	/**
677	<	* Possibly executes other tasks until this task is ready, then
678	<	* returns the result of the computation.  This method may be more
679	<	* efficient than {@code join}, but is only applicable when
680	<	* there are no potential dependencies between continuation of the
681	<	* current task and that of any other task that might be executed
682	<	* while helping. (This usually holds for pure divide-and-conquer
683	<	* tasks). This method may be invoked only from within
684	<	* ForkJoinTask computations (as may be determined using method
685	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
686	<	* result in exceptions or errors, possibly including
687	<	* ClassCastException.
688	<	*
689	<	* @return the computed result
690	<	*/
691	<	public final V helpJoin() {
692	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
693	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
694	<	reportException(busyJoin(w));
695	<	return getRawResult();
696	<	}
697	<
698	<	/**
699	<	* Possibly executes other tasks until this task is ready.  This
700	<	* method may be invoked only from within ForkJoinTask
701	<	* computations (as may be determined using method {@link
702	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
703	<	* in exceptions or errors, possibly including ClassCastException.
704	<	*/
705	<	public final void quietlyHelpJoin() {
706	<	if (status >= 0) {
707	<	ForkJoinWorkerThread w =
708	<	(ForkJoinWorkerThread) Thread.currentThread();
709	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
710	<	busyJoin(w);
670	>	Thread t = Thread.currentThread();
671	>	ForkJoinPool pool;
672	>	if (t instanceof ForkJoinWorkerThread) {
673	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
674	>	if (status >= 0 && w.unpushTask(this))
675	>	tryExec();
676	>	pool = w.pool;
677	>	}
678	>	else
679	>	pool = null;
680	>	/*
681	>	* Timed wait loop intermixes cases for fj (pool != null) and
682	>	* non FJ threads. For FJ, decrement pool count but don't try
683	>	* for replacement; increment count on completion. For non-FJ,
684	>	* deal with interrupts. This is messy, but a little less so
685	>	* than is splitting the FJ and nonFJ cases.
686	>	*/
687	>	boolean interrupted = false;
688	>	boolean dec = false; // true if pool count decremented
689	>	for (;;) {
690	>	if (Thread.interrupted() && pool == null) {
691	>	interrupted = true;
692	>	break;
693	>	}
694	>	int s = status;
695	>	if (s < 0)
696	>	break;
697	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
698	>	s, s | SIGNAL)) {
699	>	long startTime = System.nanoTime();
700	>	long nanos = unit.toNanos(timeout);
701	>	long nt; // wait time
702	>	while (status >= 0 &&
703	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
704	>	if (pool != null && !dec)
705	>	dec = pool.tryDecrementRunningCount();
706	>	else {
707	>	long ms = nt / 1000000;
708	>	int ns = (int) (nt % 1000000);
709	>	try {
710	>	synchronized(this) {
711	>	if (status >= 0)
712	>	wait(ms, ns);
713	>	}
714	>	} catch (InterruptedException ie) {
715	>	if (pool != null)
716	>	cancelIfTerminating();
717	>	else {
718	>	interrupted = true;
719	>	break;
720	>	}
721	>	}
722	>	}
723	>	}
724	>	break;
725	>	}
726		}
727	+	if (pool != null && dec)
728	+	pool.incrementRunningCount();
729	+	if (interrupted)
730	+	throw new InterruptedException();
731	+	int es = status;
732	+	if (es != NORMAL) {
733	+	Throwable ex;
734	+	if (es == CANCELLED)
735	+	throw new CancellationException();
736	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
737	+	throw new ExecutionException(ex);
738	+	throw new TimeoutException();
739	+	}
740	+	return getRawResult();
741		}
742
743		/**
#	Line 829 | Line 747 | public abstract class ForkJoinTask<V> im
747		* known to have aborted.
748		*/
749		public final void quietlyJoin() {
750	<	if (status >= 0) {
833	<	ForkJoinWorkerThread w = getWorker();
834	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
835	<	awaitDone(w, true);
836	<	}
750	>	doJoin();
751		}
752
753		/**
#	Line 844 | Line 758 | public abstract class ForkJoinTask<V> im
758		* known to have aborted.
759		*/
760		public final void quietlyInvoke() {
761	<	if (status >= 0 && !tryQuietlyInvoke())
848	<	quietlyJoin();
761	>	doInvoke();
762		}
763
764		/**
765		* Possibly executes tasks until the pool hosting the current task
766	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
767	<	* designs in which many tasks are forked, but none are explicitly
768	<	* joined, instead executing them until all are processed.
766	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
767	>	* be of use in designs in which many tasks are forked, but none
768	>	* are explicitly joined, instead executing them until all are
769	>	* processed.
770	>	*
771	>	* <p>This method may be invoked only from within {@code
772	>	* ForkJoinTask} computations (as may be determined using method
773	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
774	>	* result in exceptions or errors, possibly including {@code
775	>	* ClassCastException}.
776		*/
777		public static void helpQuiesce() {
778		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 865 | Line 785 | public abstract class ForkJoinTask<V> im
785		* this task, but only if reuse occurs when this task has either
786		* never been forked, or has been forked, then completed and all
787		* outstanding joins of this task have also completed. Effects
788	<	* under any other usage conditions are not guaranteed, and are
789	<	* almost surely wrong. This method may be useful when executing
788	>	* under any other usage conditions are not guaranteed.
789	>	* This method may be useful when executing
790		* pre-constructed trees of subtasks in loops.
791		*/
792		public void reinitialize() {
793	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
793	>	if (status == EXCEPTIONAL)
794		exceptionMap.remove(this);
795		status = 0;
796		}
#	Line 879 | Line 799 | public abstract class ForkJoinTask<V> im
799		* Returns the pool hosting the current task execution, or null
800		* if this task is executing outside of any ForkJoinPool.
801		*
802	<	* @return the pool, or null if none
802	>	* @see #inForkJoinPool
803	>	* @return the pool, or {@code null} if none
804		*/
805		public static ForkJoinPool getPool() {
806		Thread t = Thread.currentThread();
#	Line 904 | Line 825 | public abstract class ForkJoinTask<V> im
825		* by the current thread, and has not commenced executing in
826		* another thread.  This method may be useful when arranging
827		* alternative local processing of tasks that could have been, but
828	<	* were not, stolen. This method may be invoked only from within
829	<	* ForkJoinTask computations (as may be determined using method
830	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
831	<	* result in exceptions or errors, possibly including
832	<	* ClassCastException.
828	>	* were not, stolen.
829	>	*
830	>	* <p>This method may be invoked only from within {@code
831	>	* ForkJoinTask} computations (as may be determined using method
832	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
833	>	* result in exceptions or errors, possibly including {@code
834	>	* ClassCastException}.
835		*
836	<	* @return true if unforked
836	>	* @return {@code true} if unforked
837		*/
838		public boolean tryUnfork() {
839		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 923 | Line 846 | public abstract class ForkJoinTask<V> im
846		* value may be useful for heuristic decisions about whether to
847		* fork other tasks.
848		*
849	+	* <p>This method may be invoked only from within {@code
850	+	* ForkJoinTask} computations (as may be determined using method
851	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
852	+	* result in exceptions or errors, possibly including {@code
853	+	* ClassCastException}.
854	+	*
855		* @return the number of tasks
856		*/
857		public static int getQueuedTaskCount() {
#	Line 940 | Line 869 | public abstract class ForkJoinTask<V> im
869		* tasks, and to process computations locally if this threshold is
870		* exceeded.
871		*
872	+	* <p>This method may be invoked only from within {@code
873	+	* ForkJoinTask} computations (as may be determined using method
874	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
875	+	* result in exceptions or errors, possibly including {@code
876	+	* ClassCastException}.
877	+	*
878		* @return the surplus number of tasks, which may be negative
879		*/
880		public static int getSurplusQueuedTaskCount() {
#	Line 950 | Line 885 | public abstract class ForkJoinTask<V> im
885		// Extension methods
886
887		/**
888	<	* Returns the result that would be returned by {@code join},
889	<	* even if this task completed abnormally, or null if this task is
890	<	* not known to have been completed.  This method is designed to
891	<	* aid debugging, as well as to support extensions. Its use in any
892	<	* other context is discouraged.
888	>	* Returns the result that would be returned by {@link #join}, even
889	>	* if this task completed abnormally, or {@code null} if this task
890	>	* is not known to have been completed.  This method is designed
891	>	* to aid debugging, as well as to support extensions. Its use in
892	>	* any other context is discouraged.
893		*
894	<	* @return the result, or null if not completed
894	>	* @return the result, or {@code null} if not completed
895		*/
896		public abstract V getRawResult();
897
#	Line 975 | Line 910 | public abstract class ForkJoinTask<V> im
910		* called otherwise. The return value controls whether this task
911		* is considered to be done normally. It may return false in
912		* asynchronous actions that require explicit invocations of
913	<	* {@code complete} to become joinable. It may throw exceptions
914	<	* to indicate abnormal exit.
913	>	* {@link #complete} to become joinable. It may also throw an
914	>	* (unchecked) exception to indicate abnormal exit.
915		*
916	<	* @return true if completed normally
982	<	* @throws Error or RuntimeException if encountered during computation
916	>	* @return {@code true} if completed normally
917		*/
918		protected abstract boolean exec();
919
920		/**
921	<	* Returns, but does not unschedule or execute, the task queued by
922	<	* the current thread but not yet executed, if one is
921	>	* Returns, but does not unschedule or execute, a task queued by
922	>	* the current thread but not yet executed, if one is immediately
923		* available. There is no guarantee that this task will actually
924	<	* be polled or executed next.  This method is designed primarily
925	<	* to support extensions, and is unlikely to be useful otherwise.
926	<	* This method may be invoked only from within ForkJoinTask
927	<	* computations (as may be determined using method {@link
928	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
929	<	* in exceptions or errors, possibly including ClassCastException.
924	>	* be polled or executed next. Conversely, this method may return
925	>	* null even if a task exists but cannot be accessed without
926	>	* contention with other threads.  This method is designed
927	>	* primarily to support extensions, and is unlikely to be useful
928	>	* otherwise.
929	>	*
930	>	* <p>This method may be invoked only from within {@code
931	>	* ForkJoinTask} computations (as may be determined using method
932	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
933	>	* result in exceptions or errors, possibly including {@code
934	>	* ClassCastException}.
935		*
936	<	* @return the next task, or null if none are available
936	>	* @return the next task, or {@code null} if none are available
937		*/
938		protected static ForkJoinTask<?> peekNextLocalTask() {
939		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 1005 | Line 944 | public abstract class ForkJoinTask<V> im
944		* Unschedules and returns, without executing, the next task
945		* queued by the current thread but not yet executed.  This method
946		* is designed primarily to support extensions, and is unlikely to
947	<	* be useful otherwise.  This method may be invoked only from
1009	<	* within ForkJoinTask computations (as may be determined using
1010	<	* method {@link #inForkJoinPool}). Attempts to invoke in other
1011	<	* contexts result in exceptions or errors, possibly including
1012	<	* ClassCastException.
947	>	* be useful otherwise.
948		*
949	<	* @return the next task, or null if none are available
949	>	* <p>This method may be invoked only from within {@code
950	>	* ForkJoinTask} computations (as may be determined using method
951	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
952	>	* result in exceptions or errors, possibly including {@code
953	>	* ClassCastException}.
954	>	*
955	>	* @return the next task, or {@code null} if none are available
956		*/
957		protected static ForkJoinTask<?> pollNextLocalTask() {
958		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 1026 | Line 967 | public abstract class ForkJoinTask<V> im
967		* {@code null} result does not necessarily imply quiescence
968		* of the pool this task is operating in.  This method is designed
969		* primarily to support extensions, and is unlikely to be useful
970	<	* otherwise.  This method may be invoked only from within
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
974	<	* ClassCastException.
970	>	* otherwise.
971	>	*
972	>	* <p>This method may be invoked only from within {@code
973	>	* ForkJoinTask} computations (as may be determined using method
974	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
975	>	* result in exceptions or errors, possibly including {@code
976	>	* ClassCastException}.
977		*
978	<	* @return a task, or null if none are available
978	>	* @return a task, or {@code null} if none are available
979		*/
980		protected static ForkJoinTask<?> pollTask() {
981		return ((ForkJoinWorkerThread) Thread.currentThread())
982		.pollTask();
983		}
984
985	<	// adaptors
985	>	/**
986	>	* Adaptor for Runnables. This implements RunnableFuture
987	>	* to be compliant with AbstractExecutorService constraints
988	>	* when used in ForkJoinPool.
989	>	*/
990	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
991	>	implements RunnableFuture<T> {
992	>	final Runnable runnable;
993	>	final T resultOnCompletion;
994	>	T result;
995	>	AdaptedRunnable(Runnable runnable, T result) {
996	>	if (runnable == null) throw new NullPointerException();
997	>	this.runnable = runnable;
998	>	this.resultOnCompletion = result;
999	>	}
1000	>	public T getRawResult() { return result; }
1001	>	public void setRawResult(T v) { result = v; }
1002	>	public boolean exec() {
1003	>	runnable.run();
1004	>	result = resultOnCompletion;
1005	>	return true;
1006	>	}
1007	>	public void run() { invoke(); }
1008	>	private static final long serialVersionUID = 5232453952276885070L;
1009	>	}
1010	>
1011	>	/**
1012	>	* Adaptor for Callables
1013	>	*/
1014	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1015	>	implements RunnableFuture<T> {
1016	>	final Callable<? extends T> callable;
1017	>	T result;
1018	>	AdaptedCallable(Callable<? extends T> callable) {
1019	>	if (callable == null) throw new NullPointerException();
1020	>	this.callable = callable;
1021	>	}
1022	>	public T getRawResult() { return result; }
1023	>	public void setRawResult(T v) { result = v; }
1024	>	public boolean exec() {
1025	>	try {
1026	>	result = callable.call();
1027	>	return true;
1028	>	} catch (Error err) {
1029	>	throw err;
1030	>	} catch (RuntimeException rex) {
1031	>	throw rex;
1032	>	} catch (Exception ex) {
1033	>	throw new RuntimeException(ex);
1034	>	}
1035	>	}
1036	>	public void run() { invoke(); }
1037	>	private static final long serialVersionUID = 2838392045355241008L;
1038	>	}
1039
1040		/**
1041	<	* Returns a new ForkJoinTask that performs the {@code run}
1042	<	* method of the given Runnable as its action, and returns a null
1043	<	* result upon {@code join}.
1041	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1042	>	* method of the given {@code Runnable} as its action, and returns
1043	>	* a null result upon {@link #join}.
1044		*
1045		* @param runnable the runnable action
1046		* @return the task
1047		*/
1048	<	public static ForkJoinTask<Void> adapt(Runnable runnable) {
1049	<	return new ForkJoinPool.AdaptedRunnable<Void>(runnable, null);
1048	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1049	>	return new AdaptedRunnable<Void>(runnable, null);
1050		}
1051
1052		/**
1053	<	* Returns a new ForkJoinTask that performs the {@code run}
1054	<	* method of the given Runnable as its action, and returns the
1055	<	* given result upon {@code join}.
1053	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1054	>	* method of the given {@code Runnable} as its action, and returns
1055	>	* the given result upon {@link #join}.
1056		*
1057		* @param runnable the runnable action
1058		* @param result the result upon completion
1059		* @return the task
1060		*/
1061		public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1062	<	return new ForkJoinPool.AdaptedRunnable<T>(runnable, result);
1062	>	return new AdaptedRunnable<T>(runnable, result);
1063		}
1064
1065		/**
1066	<	* Returns a new ForkJoinTask that performs the {@code call}
1067	<	* method of the given Callable as its action, and returns its
1068	<	* result upon {@code join}, translating any checked
1069	<	* exceptions encountered into {@code RuntimeException}.
1066	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1067	>	* method of the given {@code Callable} as its action, and returns
1068	>	* its result upon {@link #join}, translating any checked exceptions
1069	>	* encountered into {@code RuntimeException}.
1070		*
1071		* @param callable the callable action
1072		* @return the task
1073		*/
1074	<	public static <T> ForkJoinTask<T> adapt(Callable<T> callable) {
1075	<	return new ForkJoinPool.AdaptedCallable<T>(callable);
1074	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1075	>	return new AdaptedCallable<T>(callable);
1076		}
1077
1078		// Serialization support
#	Line 1084 | Line 1080 | public abstract class ForkJoinTask<V> im
1080		private static final long serialVersionUID = -7721805057305804111L;
1081
1082		/**
1083	<	* Save the state to a stream.
1083	>	* Saves the state to a stream.
1084		*
1085		* @serialData the current run status and the exception thrown
1086	<	* during execution, or null if none
1086	>	* during execution, or {@code null} if none
1087		* @param s the stream
1088		*/
1089		private void writeObject(java.io.ObjectOutputStream s)
#	Line 1097 | Line 1093 | public abstract class ForkJoinTask<V> im
1093		}
1094
1095		/**
1096	<	* Reconstitute the instance from a stream.
1096	>	* Reconstitutes the instance from a stream.
1097		*
1098		* @param s the stream
1099		*/
1100		private void readObject(java.io.ObjectInputStream s)
1101		throws java.io.IOException, ClassNotFoundException {
1102		s.defaultReadObject();
1107	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1108	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1103		Object ex = s.readObject();
1104		if (ex != null)
1105	<	setDoneExceptionally((Throwable) ex);
1105	>	setExceptionalCompletion((Throwable) ex);
1106	>	if (status < 0)
1107	>	synchronized (this) { notifyAll(); }
1108	>	}
1109	>
1110	>	// Unsafe mechanics
1111	>
1112	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1113	>	private static final long statusOffset =
1114	>	objectFieldOffset("status", ForkJoinTask.class);
1115	>
1116	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1117	>	try {
1118	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1119	>	} catch (NoSuchFieldException e) {
1120	>	// Convert Exception to corresponding Error
1121	>	NoSuchFieldError error = new NoSuchFieldError(field);
1122	>	error.initCause(e);
1123	>	throw error;
1124	>	}
1125		}
1126
1127	<	// Unsafe mechanics for jsr166y 3rd party package.
1127	>	/**
1128	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1129	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1130	>	* into a jdk.
1131	>	*
1132	>	* @return a sun.misc.Unsafe
1133	>	*/
1134		private static sun.misc.Unsafe getUnsafe() {
1135		try {
1136		return sun.misc.Unsafe.getUnsafe();
1137		} catch (SecurityException se) {
1138		try {
1139		return java.security.AccessController.doPrivileged
1140	<	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1140	>	(new java.security
1141	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1142		public sun.misc.Unsafe run() throws Exception {
1143	<	return getUnsafeByReflection();
1143	>	java.lang.reflect.Field f = sun.misc
1144	>	.Unsafe.class.getDeclaredField("theUnsafe");
1145	>	f.setAccessible(true);
1146	>	return (sun.misc.Unsafe) f.get(null);
1147		}});
1148		} catch (java.security.PrivilegedActionException e) {
1149		throw new RuntimeException("Could not initialize intrinsics",
#	Line 1128 | Line 1151 | public abstract class ForkJoinTask<V> im
1151		}
1152		}
1153		}
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	–
1154		}

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