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Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.24 by jsr166, Mon Jul 27 21:41:53 2009 UTC vs.
Revision 1.77 by jsr166, Tue Mar 15 19:47:02 2011 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3		* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7		package jsr166y;
8
9	–	import java.util.concurrent.*;
10	–
9		import java.io.Serializable;
10		import java.util.Collection;
11		import java.util.Collections;
12		import java.util.List;
13	+	import java.util.RandomAccess;
14		import java.util.Map;
15	<	import java.util.WeakHashMap;
15	>	import java.lang.ref.WeakReference;
16	>	import java.lang.ref.ReferenceQueue;
17	>	import java.util.concurrent.Callable;
18	>	import java.util.concurrent.CancellationException;
19	>	import java.util.concurrent.ExecutionException;
20	>	import java.util.concurrent.Executor;
21	>	import java.util.concurrent.ExecutorService;
22	>	import java.util.concurrent.Future;
23	>	import java.util.concurrent.RejectedExecutionException;
24	>	import java.util.concurrent.RunnableFuture;
25	>	import java.util.concurrent.TimeUnit;
26	>	import java.util.concurrent.TimeoutException;
27	>	import java.util.concurrent.locks.ReentrantLock;
28	>	import java.lang.reflect.Constructor;
29
30		/**
31	<	* Abstract base class for tasks that run within a {@link
32	<	* ForkJoinPool}.  A ForkJoinTask is a thread-like entity that is much
31	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
32	>	* A {@code ForkJoinTask} is a thread-like entity that is much
33		* lighter weight than a normal thread.  Huge numbers of tasks and
34		* subtasks may be hosted by a small number of actual threads in a
35		* ForkJoinPool, at the price of some usage limitations.
36		*
37	<	* <p> A "main" ForkJoinTask begins execution when submitted to a
38	<	* {@link ForkJoinPool}. Once started, it will usually in turn start
39	<	* other subtasks.  As indicated by the name of this class, many
40	<	* programs using ForkJoinTasks employ only methods {@code fork} and
41	<	* {@code join}, or derivatives such as {@code invokeAll}.  However,
42	<	* this class also provides a number of other methods that can come
43	<	* into play in advanced usages, as well as extension mechanics that
44	<	* allow support of new forms of fork/join processing.
37	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
38	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
39	>	* start other subtasks.  As indicated by the name of this class,
40	>	* many programs using {@code ForkJoinTask} employ only methods
41	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
42	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
43	>	* provides a number of other methods that can come into play in
44	>	* advanced usages, as well as extension mechanics that allow
45	>	* support of new forms of fork/join processing.
46		*
47	<	* <p>A ForkJoinTask is a lightweight form of {@link Future}.  The
48	<	* efficiency of ForkJoinTasks stems from a set of restrictions (that
49	<	* are only partially statically enforceable) reflecting their
50	<	* intended use as computational tasks calculating pure functions or
51	<	* operating on purely isolated objects.  The primary coordination
52	<	* mechanisms are {@link #fork}, that arranges asynchronous execution,
53	<	* and {@link #join}, that doesn't proceed until the task's result has
54	<	* been computed.  Computations should avoid {@code synchronized}
55	<	* methods or blocks, and should minimize other blocking
56	<	* synchronization apart from joining other tasks or using
57	<	* synchronizers such as Phasers that are advertised to cooperate with
58	<	* fork/join scheduling. Tasks should also not perform blocking IO,
59	<	* and should ideally access variables that are completely independent
60	<	* of those accessed by other running tasks. Minor breaches of these
61	<	* restrictions, for example using shared output streams, may be
62	<	* tolerable in practice, but frequent use may result in poor
63	<	* performance, and the potential to indefinitely stall if the number
64	<	* of threads not waiting for IO or other external synchronization
65	<	* becomes exhausted. This usage restriction is in part enforced by
66	<	* not permitting checked exceptions such as {@code IOExceptions}
67	<	* to be thrown. However, computations may still encounter unchecked
68	<	* exceptions, that are rethrown to callers attempting join
69	<	* them. These exceptions may additionally include
70	<	* RejectedExecutionExceptions stemming from internal resource
71	<	* exhaustion such as failure to allocate internal task queues.
47	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
48	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
49	>	* restrictions (that are only partially statically enforceable)
50	>	* reflecting their intended use as computational tasks calculating
51	>	* pure functions or operating on purely isolated objects.  The
52	>	* primary coordination mechanisms are {@link #fork}, that arranges
53	>	* asynchronous execution, and {@link #join}, that doesn't proceed
54	>	* until the task's result has been computed.  Computations should
55	>	* avoid {@code synchronized} methods or blocks, and should minimize
56	>	* other blocking synchronization apart from joining other tasks or
57	>	* using synchronizers such as Phasers that are advertised to
58	>	* cooperate with fork/join scheduling. Tasks should also not perform
59	>	* blocking IO, and should ideally access variables that are
60	>	* completely independent of those accessed by other running
61	>	* tasks. Minor breaches of these restrictions, for example using
62	>	* shared output streams, may be tolerable in practice, but frequent
63	>	* use may result in poor performance, and the potential to
64	>	* indefinitely stall if the number of threads not waiting for IO or
65	>	* other external synchronization becomes exhausted. This usage
66	>	* restriction is in part enforced by not permitting checked
67	>	* exceptions such as {@code IOExceptions} to be thrown. However,
68	>	* computations may still encounter unchecked exceptions, that are
69	>	* rethrown to callers attempting to join them. These exceptions may
70	>	* additionally include {@link RejectedExecutionException} stemming
71	>	* from internal resource exhaustion, such as failure to allocate
72	>	* internal task queues. Rethrown exceptions behave in the same way as
73	>	* regular exceptions, but, when possible, contain stack traces (as
74	>	* displayed for example using {@code ex.printStackTrace()}) of both
75	>	* the thread that initiated the computation as well as the thread
76	>	* actually encountering the exception; minimally only the latter.
77		*
78		* <p>The primary method for awaiting completion and extracting
79		* results of a task is {@link #join}, but there are several variants:
80		* The {@link Future#get} methods support interruptible and/or timed
81		* waits for completion and report results using {@code Future}
82	<	* conventions. Method {@link #helpJoin} enables callers to actively
83	<	* execute other tasks while awaiting joins, which is sometimes more
84	<	* efficient but only applies when all subtasks are known to be
85	<	* strictly tree-structured. Method {@link #invoke} is semantically
68	<	* equivalent to {@code fork(); join()} but always attempts to
69	<	* begin execution in the current thread. The "<em>quiet</em>" forms
70	<	* of these methods do not extract results or report exceptions. These
82	>	* conventions. Method {@link #invoke} is semantically
83	>	* equivalent to {@code fork(); join()} but always attempts to begin
84	>	* execution in the current thread. The "<em>quiet</em>" forms of
85	>	* these methods do not extract results or report exceptions. These
86		* may be useful when a set of tasks are being executed, and you need
87		* to delay processing of results or exceptions until all complete.
88		* Method {@code invokeAll} (available in multiple versions)
89		* performs the most common form of parallel invocation: forking a set
90		* of tasks and joining them all.
91		*
92	<	* <p> The ForkJoinTask class is not usually directly subclassed.
92	>	* <p>The execution status of tasks may be queried at several levels
93	>	* of detail: {@link #isDone} is true if a task completed in any way
94	>	* (including the case where a task was cancelled without executing);
95	>	* {@link #isCompletedNormally} is true if a task completed without
96	>	* cancellation or encountering an exception; {@link #isCancelled} is
97	>	* true if the task was cancelled (in which case {@link #getException}
98	>	* returns a {@link java.util.concurrent.CancellationException}); and
99	>	* {@link #isCompletedAbnormally} is true if a task was either
100	>	* cancelled or encountered an exception, in which case {@link
101	>	* #getException} will return either the encountered exception or
102	>	* {@link java.util.concurrent.CancellationException}.
103	>	*
104	>	* <p>The ForkJoinTask class is not usually directly subclassed.
105		* Instead, you subclass one of the abstract classes that support a
106	<	* particular style of fork/join processing.  Normally, a concrete
106	>	* particular style of fork/join processing, typically {@link
107	>	* RecursiveAction} for computations that do not return results, or
108	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
109		* ForkJoinTask subclass declares fields comprising its parameters,
110		* established in a constructor, and then defines a {@code compute}
111		* method that somehow uses the control methods supplied by this base
112		* class. While these methods have {@code public} access (to allow
113	<	* instances of different task subclasses to call each others
113	>	* instances of different task subclasses to call each other's
114		* methods), some of them may only be called from within other
115		* ForkJoinTasks (as may be determined using method {@link
116		* #inForkJoinPool}).  Attempts to invoke them in other contexts
117		* result in exceptions or errors, possibly including
118	<	* ClassCastException.
118	>	* {@code ClassCastException}.
119		*
120	<	* <p>Most base support methods are {@code final} because their
121	<	* implementations are intrinsically tied to the underlying
122	<	* lightweight task scheduling framework, and so cannot be overridden.
123	<	* Developers creating new basic styles of fork/join processing should
124	<	* minimally implement {@code protected} methods
125	<	* {@link #exec}, {@link #setRawResult}, and
126	<	* {@link #getRawResult}, while also introducing an abstract
127	<	* computational method that can be implemented in its subclasses,
128	<	* possibly relying on other {@code protected} methods provided
129	<	* by this class.
120	>	* <p>Method {@link #join} and its variants are appropriate for use
121	>	* only when completion dependencies are acyclic; that is, the
122	>	* parallel computation can be described as a directed acyclic graph
123	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
124	>	* tasks cyclically wait for each other.  However, this framework
125	>	* supports other methods and techniques (for example the use of
126	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
127	>	* may be of use in constructing custom subclasses for problems that
128	>	* are not statically structured as DAGs.
129	>	*
130	>	* <p>Most base support methods are {@code final}, to prevent
131	>	* overriding of implementations that are intrinsically tied to the
132	>	* underlying lightweight task scheduling framework.  Developers
133	>	* creating new basic styles of fork/join processing should minimally
134	>	* implement {@code protected} methods {@link #exec}, {@link
135	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
136	>	* an abstract computational method that can be implemented in its
137	>	* subclasses, possibly relying on other {@code protected} methods
138	>	* provided by this class.
139		*
140		* <p>ForkJoinTasks should perform relatively small amounts of
141	<	* computations, otherwise splitting into smaller tasks. As a very
142	<	* rough rule of thumb, a task should perform more than 100 and less
143	<	* than 10000 basic computational steps. If tasks are too big, then
144	<	* parallelism cannot improve throughput. If too small, then memory
145	<	* and internal task maintenance overhead may overwhelm processing.
141	>	* computation. Large tasks should be split into smaller subtasks,
142	>	* usually via recursive decomposition. As a very rough rule of thumb,
143	>	* a task should perform more than 100 and less than 10000 basic
144	>	* computational steps, and should avoid indefinite looping. If tasks
145	>	* are too big, then parallelism cannot improve throughput. If too
146	>	* small, then memory and internal task maintenance overhead may
147	>	* overwhelm processing.
148	>	*
149	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
150	>	* and {@link Callable}, that may be of use when mixing execution of
151	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
152	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
153		*
154	<	* <p>ForkJoinTasks are {@code Serializable}, which enables them
155	<	* to be used in extensions such as remote execution frameworks. It is
156	<	* in general sensible to serialize tasks only before or after, but
157	<	* not during execution. Serialization is not relied on during
113	<	* execution itself.
154	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
155	>	* used in extensions such as remote execution frameworks. It is
156	>	* sensible to serialize tasks only before or after, but not during,
157	>	* execution. Serialization is not relied on during execution itself.
158		*
159		* @since 1.7
160		* @author Doug Lea
161		*/
162		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
163
164	<	/**
165	<	* Run control status bits packed into a single int to minimize
166	<	* footprint and to ensure atomicity (via CAS).  Status is
167	<	* initially zero, and takes on nonnegative values until
168	<	* completed, upon which status holds COMPLETED. CANCELLED, or
169	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
170	<	* blocking waits by other threads have SIGNAL_MASK bits set --
171	<	* bit 15 for external (nonFJ) waits, and the rest a count of
172	<	* waiting FJ threads.  (This representation relies on
173	<	* ForkJoinPool max thread limits). Completion of a stolen task
174	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
175	<	* though suboptimal for some purposes, we use basic builtin
176	<	* wait/notify to take advantage of "monitor inflation" in JVMs
177	<	* that we would otherwise need to emulate to avoid adding further
178	<	* per-task bookkeeping overhead. Note that bits 16-28 are
179	<	* currently unused. Also value 0x80000000 is available as spare
180	<	* completion value.
181	<	*/
182	<	volatile int status; // accessed directly by pool and workers
183	<
184	<	static final int COMPLETION_MASK      = 0xe0000000;
185	<	static final int NORMAL               = 0xe0000000; // == mask
186	<	static final int CANCELLED            = 0xc0000000;
187	<	static final int EXCEPTIONAL          = 0xa0000000;
188	<	static final int SIGNAL_MASK          = 0x0000ffff;
189	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
190	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
147	<
148	<	/**
149	<	* Table of exceptions thrown by tasks, to enable reporting by
150	<	* callers. Because exceptions are rare, we don't directly keep
151	<	* them with task objects, but instead use a weak ref table.  Note
152	<	* that cancellation exceptions don't appear in the table, but are
153	<	* instead recorded as status values.
154	<	* TODO: Use ConcurrentReferenceHashMap
164	>	/*
165	>	* See the internal documentation of class ForkJoinPool for a
166	>	* general implementation overview.  ForkJoinTasks are mainly
167	>	* responsible for maintaining their "status" field amidst relays
168	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
169	>	* methods of this class are more-or-less layered into (1) basic
170	>	* status maintenance (2) execution and awaiting completion (3)
171	>	* user-level methods that additionally report results. This is
172	>	* sometimes hard to see because this file orders exported methods
173	>	* in a way that flows well in javadocs.
174	>	*/
175	>
176	>	/*
177	>	* The status field holds run control status bits packed into a
178	>	* single int to minimize footprint and to ensure atomicity (via
179	>	* CAS).  Status is initially zero, and takes on nonnegative
180	>	* values until completed, upon which status holds value
181	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
182	>	* waits by other threads have the SIGNAL bit set.  Completion of
183	>	* a stolen task with SIGNAL set awakens any waiters via
184	>	* notifyAll. Even though suboptimal for some purposes, we use
185	>	* basic builtin wait/notify to take advantage of "monitor
186	>	* inflation" in JVMs that we would otherwise need to emulate to
187	>	* avoid adding further per-task bookkeeping overhead.  We want
188	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
189	>	* techniques, so use some odd coding idioms that tend to avoid
190	>	* them.
191		*/
156	–	static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
157	–	Collections.synchronizedMap
158	–	(new WeakHashMap<ForkJoinTask<?>, Throwable>());
159	–
160	–	// within-package utilities
192
193	<	/**
194	<	* Gets current worker thread, or null if not a worker thread.
195	<	*/
196	<	static ForkJoinWorkerThread getWorker() {
197	<	Thread t = Thread.currentThread();
198	<	return ((t instanceof ForkJoinWorkerThread) ?
168	<	(ForkJoinWorkerThread) t : null);
169	<	}
170	<
171	<	final boolean casStatus(int cmp, int val) {
172	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
173	<	}
174	<
175	<	/**
176	<	* Workaround for not being able to rethrow unchecked exceptions.
177	<	*/
178	<	static void rethrowException(Throwable ex) {
179	<	if (ex != null)
180	<	UNSAFE.throwException(ex);
181	<	}
182	<
183	<	// Setting completion status
193	>	/** The run status of this task */
194	>	volatile int status; // accessed directly by pool and workers
195	>	private static final int NORMAL      = -1;
196	>	private static final int CANCELLED   = -2;
197	>	private static final int EXCEPTIONAL = -3;
198	>	private static final int SIGNAL      =  1;
199
200		/**
201	<	* Marks completion and wakes up threads waiting to join this task.
201	>	* Marks completion and wakes up threads waiting to join this task,
202	>	* also clearing signal request bits.
203		*
204		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
205	+	* @return completion status on exit
206		*/
207	<	final void setCompletion(int completion) {
208	<	ForkJoinPool pool = getPool();
209	<	if (pool != null) {
210	<	int s; // Clear signal bits while setting completion status
211	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
212	<
213	<	if ((s & SIGNAL_MASK) != 0) {
214	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
198	<	pool.updateRunningCount(s);
199	<	synchronized (this) { notifyAll(); }
207	>	private int setCompletion(int completion) {
208	>	for (int s;;) {
209	>	if ((s = status) < 0)
210	>	return s;
211	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
212	>	if (s != 0)
213	>	synchronized (this) { notifyAll(); }
214	>	return completion;
215		}
216		}
202	–	else
203	–	externallySetCompletion(completion);
217		}
218
219		/**
220	<	* Version of setCompletion for non-FJ threads.  Leaves signal
221	<	* bits for unblocked threads to adjust, and always notifies.
220	>	* Tries to block a worker thread until completed or timed out.
221	>	* Uses Object.wait time argument conventions.
222	>	* May fail on contention or interrupt.
223	>	*
224	>	* @param millis if > 0, wait time.
225		*/
226	<	private void externallySetCompletion(int completion) {
226	>	final void tryAwaitDone(long millis) {
227		int s;
212	–	do {} while ((s = status) >= 0 &&
213	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
214	–	synchronized (this) { notifyAll(); }
215	–	}
216	–
217	–	/**
218	–	* Sets status to indicate normal completion.
219	–	*/
220	–	final void setNormalCompletion() {
221	–	// Try typical fast case -- single CAS, no signal, not already done.
222	–	// Manually expand casStatus to improve chances of inlining it
223	–	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
224	–	setCompletion(NORMAL);
225	–	}
226	–
227	–	// internal waiting and notification
228	–
229	–	/**
230	–	* Performs the actual monitor wait for awaitDone.
231	–	*/
232	–	private void doAwaitDone() {
233	–	// Minimize lock bias and in/de-flation effects by maximizing
234	–	// chances of waiting inside sync
228		try {
229	<	while (status >= 0)
230	<	synchronized (this) { if (status >= 0) wait(); }
231	<	} catch (InterruptedException ie) {
232	<	onInterruptedWait();
233	<	}
234	<	}
235	<
243	<	/**
244	<	* Performs the actual timed monitor wait for awaitDone.
245	<	*/
246	<	private void doAwaitDone(long startTime, long nanos) {
247	<	synchronized (this) {
248	<	try {
249	<	while (status >= 0) {
250	<	long nt = nanos - System.nanoTime() - startTime;
251	<	if (nt <= 0)
252	<	break;
253	<	wait(nt / 1000000, (int) (nt % 1000000));
229	>	if (((s = status) > 0 ||
230	>	(s == 0 &&
231	>	UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) &&
232	>	status > 0) {
233	>	synchronized (this) {
234	>	if (status > 0)
235	>	wait(millis);
236		}
255	–	} catch (InterruptedException ie) {
256	–	onInterruptedWait();
237		}
238	+	} catch (InterruptedException ie) {
239	+	// caller must check termination
240		}
241		}
242
261	–	// Awaiting completion
262	–
243		/**
244	<	* Sets status to indicate there is joiner, then waits for join,
245	<	* surrounded with pool notifications.
266	<	*
267	<	* @return status upon exit
244	>	* Blocks a non-worker-thread until completion.
245	>	* @return status upon completion
246		*/
247	<	private int awaitDone(ForkJoinWorkerThread w,
270	<	boolean maintainParallelism) {
271	<	ForkJoinPool pool = (w == null) ? null : w.pool;
247	>	private int externalAwaitDone() {
248		int s;
249	<	while ((s = status) >= 0) {
250	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
251	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
252	<	doAwaitDone();
253	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
254	<	adjustPoolCountsOnUnblock(pool);
255	<	break;
249	>	if ((s = status) >= 0) {
250	>	boolean interrupted = false;
251	>	synchronized (this) {
252	>	while ((s = status) >= 0) {
253	>	if (s == 0)
254	>	UNSAFE.compareAndSwapInt(this, statusOffset,
255	>	0, SIGNAL);
256	>	else {
257	>	try {
258	>	wait();
259	>	} catch (InterruptedException ie) {
260	>	interrupted = true;
261	>	}
262	>	}
263	>	}
264		}
265	+	if (interrupted)
266	+	Thread.currentThread().interrupt();
267		}
268		return s;
269		}
270
271		/**
272	<	* Timed version of awaitDone
287	<	*
288	<	* @return status upon exit
272	>	* Blocks a non-worker-thread until completion or interruption or timeout.
273		*/
274	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
275	<	ForkJoinPool pool = (w == null) ? null : w.pool;
274	>	private int externalInterruptibleAwaitDone(long millis)
275	>	throws InterruptedException {
276		int s;
277	<	while ((s = status) >= 0) {
278	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
279	<	long startTime = System.nanoTime();
280	<	if (pool == null || !pool.preJoin(this, false))
281	<	doAwaitDone(startTime, nanos);
282	<	if ((s = status) >= 0) {
283	<	adjustPoolCountsOnCancelledWait(pool);
284	<	s = status;
277	>	if (Thread.interrupted())
278	>	throw new InterruptedException();
279	>	if ((s = status) >= 0) {
280	>	synchronized (this) {
281	>	while ((s = status) >= 0) {
282	>	if (s == 0)
283	>	UNSAFE.compareAndSwapInt(this, statusOffset,
284	>	0, SIGNAL);
285	>	else {
286	>	wait(millis);
287	>	if (millis > 0L)
288	>	break;
289	>	}
290		}
302	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
303	–	adjustPoolCountsOnUnblock(pool);
304	–	break;
291		}
292		}
293		return s;
294		}
295
296		/**
297	<	* Notifies pool that thread is unblocked. Called by signalled
298	<	* threads when woken by non-FJ threads (which is atypical).
297	>	* Primary execution method for stolen tasks. Unless done, calls
298	>	* exec and records status if completed, but doesn't wait for
299	>	* completion otherwise.
300		*/
301	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
302	<	int s;
303	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
304	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
305	<	pool.updateRunningCount(s);
301	>	final void doExec() {
302	>	if (status >= 0) {
303	>	boolean completed;
304	>	try {
305	>	completed = exec();
306	>	} catch (Throwable rex) {
307	>	setExceptionalCompletion(rex);
308	>	return;
309	>	}
310	>	if (completed)
311	>	setCompletion(NORMAL); // must be outside try block
312	>	}
313		}
314
315		/**
316	<	* Notifies pool to adjust counts on cancelled or timed out wait.
316	>	* Primary mechanics for join, get, quietlyJoin.
317	>	* @return status upon completion
318		*/
319	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
320	<	if (pool != null) {
321	<	int s;
322	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
323	<	if (casStatus(s, s - 1)) {
324	<	pool.updateRunningCount(1);
325	<	break;
319	>	private int doJoin() {
320	>	Thread t; ForkJoinWorkerThread w; int s; boolean completed;
321	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
322	>	if ((s = status) < 0)
323	>	return s;
324	>	if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) {
325	>	try {
326	>	completed = exec();
327	>	} catch (Throwable rex) {
328	>	return setExceptionalCompletion(rex);
329		}
330	+	if (completed)
331	+	return setCompletion(NORMAL);
332		}
333	+	return w.joinTask(this);
334		}
335	+	else
336	+	return externalAwaitDone();
337		}
338
339		/**
340	<	* Handles interruptions during waits.
340	>	* Primary mechanics for invoke, quietlyInvoke.
341	>	* @return status upon completion
342		*/
343	<	private void onInterruptedWait() {
344	<	ForkJoinWorkerThread w = getWorker();
345	<	if (w == null)
346	<	Thread.currentThread().interrupt(); // re-interrupt
347	<	else if (w.isTerminating())
348	<	cancelIgnoringExceptions();
349	<	// else if FJworker, ignore interrupt
343	>	private int doInvoke() {
344	>	int s; boolean completed;
345	>	if ((s = status) < 0)
346	>	return s;
347	>	try {
348	>	completed = exec();
349	>	} catch (Throwable rex) {
350	>	return setExceptionalCompletion(rex);
351	>	}
352	>	if (completed)
353	>	return setCompletion(NORMAL);
354	>	else
355	>	return doJoin();
356		}
357
358	<	// Recording and reporting exceptions
349	<
350	<	private void setDoneExceptionally(Throwable rex) {
351	<	exceptionMap.put(this, rex);
352	<	setCompletion(EXCEPTIONAL);
353	<	}
358	>	// Exception table support
359
360		/**
361	<	* Throws the exception associated with status s.
361	>	* Table of exceptions thrown by tasks, to enable reporting by
362	>	* callers. Because exceptions are rare, we don't directly keep
363	>	* them with task objects, but instead use a weak ref table.  Note
364	>	* that cancellation exceptions don't appear in the table, but are
365	>	* instead recorded as status values.
366		*
367	<	* @throws the exception
367	>	* Note: These statics are initialized below in static block.
368		*/
369	<	private void reportException(int s) {
370	<	if ((s &= COMPLETION_MASK) < NORMAL) {
371	<	if (s == CANCELLED)
363	<	throw new CancellationException();
364	<	else
365	<	rethrowException(exceptionMap.get(this));
366	<	}
367	<	}
369	>	private static final ExceptionNode[] exceptionTable;
370	>	private static final ReentrantLock exceptionTableLock;
371	>	private static final ReferenceQueue<Object> exceptionTableRefQueue;
372
373		/**
374	<	* Returns result or throws exception using j.u.c.Future conventions.
371	<	* Only call when {@code isDone} known to be true.
374	>	* Fixed capacity for exceptionTable.
375		*/
376	<	private V reportFutureResult()
374	<	throws ExecutionException, InterruptedException {
375	<	int s = status & COMPLETION_MASK;
376	<	if (s < NORMAL) {
377	<	Throwable ex;
378	<	if (s == CANCELLED)
379	<	throw new CancellationException();
380	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
381	<	throw new ExecutionException(ex);
382	<	if (Thread.interrupted())
383	<	throw new InterruptedException();
384	<	}
385	<	return getRawResult();
386	<	}
376	>	private static final int EXCEPTION_MAP_CAPACITY = 32;
377
378		/**
379	<	* Returns result or throws exception using j.u.c.Future conventions
380	<	* with timeouts.
379	>	* Key-value nodes for exception table.  The chained hash table
380	>	* uses identity comparisons, full locking, and weak references
381	>	* for keys. The table has a fixed capacity because it only
382	>	* maintains task exceptions long enough for joiners to access
383	>	* them, so should never become very large for sustained
384	>	* periods. However, since we do not know when the last joiner
385	>	* completes, we must use weak references and expunge them. We do
386	>	* so on each operation (hence full locking). Also, some thread in
387	>	* any ForkJoinPool will call helpExpungeStaleExceptions when its
388	>	* pool becomes isQuiescent.
389		*/
390	<	private V reportTimedFutureResult()
391	<	throws InterruptedException, ExecutionException, TimeoutException {
392	<	Throwable ex;
393	<	int s = status & COMPLETION_MASK;
394	<	if (s == NORMAL)
395	<	return getRawResult();
396	<	if (s == CANCELLED)
397	<	throw new CancellationException();
398	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
399	<	throw new ExecutionException(ex);
402	<	if (Thread.interrupted())
403	<	throw new InterruptedException();
404	<	throw new TimeoutException();
390	>	static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{
391	>	final Throwable ex;
392	>	ExceptionNode next;
393	>	final long thrower;  // use id not ref to avoid weak cycles
394	>	ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
395	>	super(task, exceptionTableRefQueue);
396	>	this.ex = ex;
397	>	this.next = next;
398	>	this.thrower = Thread.currentThread().getId();
399	>	}
400		}
401
407	–	// internal execution methods
408	–
402		/**
403	<	* Calls exec, recording completion, and rethrowing exception if
411	<	* encountered. Caller should normally check status before calling.
403	>	* Records exception and sets exceptional completion.
404		*
405	<	* @return true if completed normally
405	>	* @return status on exit
406		*/
407	<	private boolean tryExec() {
408	<	try { // try block must contain only call to exec
409	<	if (!exec())
410	<	return false;
411	<	} catch (Throwable rex) {
412	<	setDoneExceptionally(rex);
413	<	rethrowException(rex);
414	<	return false; // not reached
407	>	private int setExceptionalCompletion(Throwable ex) {
408	>	int h = System.identityHashCode(this);
409	>	final ReentrantLock lock = exceptionTableLock;
410	>	lock.lock();
411	>	try {
412	>	expungeStaleExceptions();
413	>	ExceptionNode[] t = exceptionTable;
414	>	int i = h & (t.length - 1);
415	>	for (ExceptionNode e = t[i]; ; e = e.next) {
416	>	if (e == null) {
417	>	t[i] = new ExceptionNode(this, ex, t[i]);
418	>	break;
419	>	}
420	>	if (e.get() == this) // already present
421	>	break;
422	>	}
423	>	} finally {
424	>	lock.unlock();
425		}
426	<	setNormalCompletion();
425	<	return true;
426	>	return setCompletion(EXCEPTIONAL);
427		}
428
429		/**
430	<	* Main execution method used by worker threads. Invokes
430	<	* base computation unless already complete.
430	>	* Removes exception node and clears status
431		*/
432	<	final void quietlyExec() {
433	<	if (status >= 0) {
434	<	try {
435	<	if (!exec())
436	<	return;
437	<	} catch (Throwable rex) {
438	<	setDoneExceptionally(rex);
439	<	return;
432	>	private void clearExceptionalCompletion() {
433	>	int h = System.identityHashCode(this);
434	>	final ReentrantLock lock = exceptionTableLock;
435	>	lock.lock();
436	>	try {
437	>	ExceptionNode[] t = exceptionTable;
438	>	int i = h & (t.length - 1);
439	>	ExceptionNode e = t[i];
440	>	ExceptionNode pred = null;
441	>	while (e != null) {
442	>	ExceptionNode next = e.next;
443	>	if (e.get() == this) {
444	>	if (pred == null)
445	>	t[i] = next;
446	>	else
447	>	pred.next = next;
448	>	break;
449	>	}
450	>	pred = e;
451	>	e = next;
452		}
453	<	setNormalCompletion();
453	>	expungeStaleExceptions();
454	>	status = 0;
455	>	} finally {
456	>	lock.unlock();
457		}
458		}
459
460		/**
461	<	* Calls exec(), recording but not rethrowing exception.
462	<	* Caller should normally check status before calling.
461	>	* Returns a rethrowable exception for the given task, if
462	>	* available. To provide accurate stack traces, if the exception
463	>	* was not thrown by the current thread, we try to create a new
464	>	* exception of the same type as the one thrown, but with the
465	>	* recorded exception as its cause. If there is no such
466	>	* constructor, we instead try to use a no-arg constructor,
467	>	* followed by initCause, to the same effect. If none of these
468	>	* apply, or any fail due to other exceptions, we return the
469	>	* recorded exception, which is still correct, although it may
470	>	* contain a misleading stack trace.
471		*
472	<	* @return true if completed normally
472	>	* @return the exception, or null if none
473		*/
474	<	private boolean tryQuietlyInvoke() {
474	>	private Throwable getThrowableException() {
475	>	if (status != EXCEPTIONAL)
476	>	return null;
477	>	int h = System.identityHashCode(this);
478	>	ExceptionNode e;
479	>	final ReentrantLock lock = exceptionTableLock;
480	>	lock.lock();
481		try {
482	<	if (!exec())
483	<	return false;
484	<	} catch (Throwable rex) {
485	<	setDoneExceptionally(rex);
486	<	return false;
482	>	expungeStaleExceptions();
483	>	ExceptionNode[] t = exceptionTable;
484	>	e = t[h & (t.length - 1)];
485	>	while (e != null && e.get() != this)
486	>	e = e.next;
487	>	} finally {
488	>	lock.unlock();
489		}
490	<	setNormalCompletion();
491	<	return true;
490	>	Throwable ex;
491	>	if (e == null || (ex = e.ex) == null)
492	>	return null;
493	>	if (e.thrower != Thread.currentThread().getId()) {
494	>	Class ec = ex.getClass();
495	>	try {
496	>	Constructor<?> noArgCtor = null;
497	>	Constructor<?>[] cs = ec.getConstructors();// public ctors only
498	>	for (int i = 0; i < cs.length; ++i) {
499	>	Constructor<?> c = cs[i];
500	>	Class<?>[] ps = c.getParameterTypes();
501	>	if (ps.length == 0)
502	>	noArgCtor = c;
503	>	else if (ps.length == 1 && ps[0] == Throwable.class)
504	>	return (Throwable)(c.newInstance(ex));
505	>	}
506	>	if (noArgCtor != null) {
507	>	Throwable wx = (Throwable)(noArgCtor.newInstance());
508	>	wx.initCause(ex);
509	>	return wx;
510	>	}
511	>	} catch (Exception ignore) {
512	>	}
513	>	}
514	>	return ex;
515		}
516
517		/**
518	<	* Cancels, ignoring any exceptions it throws.
518	>	* Poll stale refs and remove them. Call only while holding lock.
519		*/
520	<	final void cancelIgnoringExceptions() {
521	<	try {
522	<	cancel(false);
523	<	} catch (Throwable ignore) {
520	>	private static void expungeStaleExceptions() {
521	>	for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
522	>	if (x instanceof ExceptionNode) {
523	>	ForkJoinTask<?> key = ((ExceptionNode)x).get();
524	>	ExceptionNode[] t = exceptionTable;
525	>	int i = System.identityHashCode(key) & (t.length - 1);
526	>	ExceptionNode e = t[i];
527	>	ExceptionNode pred = null;
528	>	while (e != null) {
529	>	ExceptionNode next = e.next;
530	>	if (e == x) {
531	>	if (pred == null)
532	>	t[i] = next;
533	>	else
534	>	pred.next = next;
535	>	break;
536	>	}
537	>	pred = e;
538	>	e = next;
539	>	}
540	>	}
541		}
542		}
543
544		/**
545	<	* Main implementation of helpJoin
545	>	* If lock is available, poll stale refs and remove them.
546	>	* Called from ForkJoinPool when pools become quiescent.
547		*/
548	<	private int busyJoin(ForkJoinWorkerThread w) {
549	<	int s;
550	<	ForkJoinTask<?> t;
551	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
552	<	t.quietlyExec();
553	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
548	>	static final void helpExpungeStaleExceptions() {
549	>	final ReentrantLock lock = exceptionTableLock;
550	>	if (lock.tryLock()) {
551	>	try {
552	>	expungeStaleExceptions();
553	>	} finally {
554	>	lock.unlock();
555	>	}
556	>	}
557	>	}
558	>
559	>	/**
560	>	* Report the result of invoke or join; called only upon
561	>	* non-normal return of internal versions.
562	>	*/
563	>	private V reportResult() {
564	>	int s; Throwable ex;
565	>	if ((s = status) == CANCELLED)
566	>	throw new CancellationException();
567	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
568	>	UNSAFE.throwException(ex);
569	>	return getRawResult();
570		}
571
572		// public methods
#	Line 486 | Line 574 | public abstract class ForkJoinTask<V> im
574		/**
575		* Arranges to asynchronously execute this task.  While it is not
576		* necessarily enforced, it is a usage error to fork a task more
577	<	* than once unless it has completed and been reinitialized.  This
578	<	* method may be invoked only from within ForkJoinTask
579	<	* computations (as may be determined using method {@link
580	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
581	<	* in exceptions or errors, possibly including ClassCastException.
577	>	* than once unless it has completed and been reinitialized.
578	>	* Subsequent modifications to the state of this task or any data
579	>	* it operates on are not necessarily consistently observable by
580	>	* any thread other than the one executing it unless preceded by a
581	>	* call to {@link #join} or related methods, or a call to {@link
582	>	* #isDone} returning {@code true}.
583	>	*
584	>	* <p>This method may be invoked only from within {@code
585	>	* ForkJoinPool} computations (as may be determined using method
586	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
587	>	* result in exceptions or errors, possibly including {@code
588	>	* ClassCastException}.
589		*
590	<	* @return {@code this}, to simplify usage.
590	>	* @return {@code this}, to simplify usage
591		*/
592		public final ForkJoinTask<V> fork() {
593		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 501 | Line 596 | public abstract class ForkJoinTask<V> im
596		}
597
598		/**
599	<	* Returns the result of the computation when it is ready.
600	<	* This method differs from {@code get} in that abnormal
601	<	* completion results in RuntimeExceptions or Errors, not
602	<	* ExecutionExceptions.
599	>	* Returns the result of the computation when it {@link #isDone is
600	>	* done}.  This method differs from {@link #get()} in that
601	>	* abnormal completion results in {@code RuntimeException} or
602	>	* {@code Error}, not {@code ExecutionException}, and that
603	>	* interrupts of the calling thread do <em>not</em> cause the
604	>	* method to abruptly return by throwing {@code
605	>	* InterruptedException}.
606		*
607		* @return the computed result
608		*/
609		public final V join() {
610	<	ForkJoinWorkerThread w = getWorker();
611	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
612	<	reportException(awaitDone(w, true));
613	<	return getRawResult();
610	>	if (doJoin() != NORMAL)
611	>	return reportResult();
612	>	else
613	>	return getRawResult();
614		}
615
616		/**
617		* Commences performing this task, awaits its completion if
618	<	* necessary, and return its result.
618	>	* necessary, and returns its result, or throws an (unchecked)
619	>	* {@code RuntimeException} or {@code Error} if the underlying
620	>	* computation did so.
621		*
522	–	* @throws Throwable (a RuntimeException, Error, or unchecked
523	–	* exception) if the underlying computation did so
622		* @return the computed result
623		*/
624		public final V invoke() {
625	<	if (status >= 0 && tryExec())
626	<	return getRawResult();
625	>	if (doInvoke() != NORMAL)
626	>	return reportResult();
627		else
628	<	return join();
628	>	return getRawResult();
629		}
630
631		/**
632	<	* Forks both tasks, returning when {@code isDone} holds for
633	<	* both of them or an exception is encountered. This method may be
634	<	* invoked only from within ForkJoinTask computations (as may be
635	<	* determined using method {@link #inForkJoinPool}). Attempts to
636	<	* invoke in other contexts result in exceptions or errors,
637	<	* possibly including ClassCastException.
638	<	*
639	<	* @param t1 one task
640	<	* @param t2 the other task
641	<	* @throws NullPointerException if t1 or t2 are null
642	<	* @throws RuntimeException or Error if either task did so
632	>	* Forks the given tasks, returning when {@code isDone} holds for
633	>	* each task or an (unchecked) exception is encountered, in which
634	>	* case the exception is rethrown. If more than one task
635	>	* encounters an exception, then this method throws any one of
636	>	* these exceptions. If any task encounters an exception, the
637	>	* other may be cancelled. However, the execution status of
638	>	* individual tasks is not guaranteed upon exceptional return. The
639	>	* status of each task may be obtained using {@link
640	>	* #getException()} and related methods to check if they have been
641	>	* cancelled, completed normally or exceptionally, or left
642	>	* unprocessed.
643	>	*
644	>	* <p>This method may be invoked only from within {@code
645	>	* ForkJoinPool} computations (as may be determined using method
646	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
647	>	* result in exceptions or errors, possibly including {@code
648	>	* ClassCastException}.
649	>	*
650	>	* @param t1 the first task
651	>	* @param t2 the second task
652	>	* @throws NullPointerException if any task is null
653		*/
654	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
654	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
655		t2.fork();
656		t1.invoke();
657		t2.join();
658		}
659
660		/**
661	<	* Forks the given tasks, returning when {@code isDone} holds
662	<	* for all of them. If any task encounters an exception, others
663	<	* may be cancelled.  This method may be invoked only from within
664	<	* ForkJoinTask computations (as may be determined using method
665	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
666	<	* result in exceptions or errors, possibly including
667	<	* ClassCastException.
661	>	* Forks the given tasks, returning when {@code isDone} holds for
662	>	* each task or an (unchecked) exception is encountered, in which
663	>	* case the exception is rethrown. If more than one task
664	>	* encounters an exception, then this method throws any one of
665	>	* these exceptions. If any task encounters an exception, others
666	>	* may be cancelled. However, the execution status of individual
667	>	* tasks is not guaranteed upon exceptional return. The status of
668	>	* each task may be obtained using {@link #getException()} and
669	>	* related methods to check if they have been cancelled, completed
670	>	* normally or exceptionally, or left unprocessed.
671	>	*
672	>	* <p>This method may be invoked only from within {@code
673	>	* ForkJoinPool} computations (as may be determined using method
674	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
675	>	* result in exceptions or errors, possibly including {@code
676	>	* ClassCastException}.
677		*
678	<	* @param tasks the array of tasks
679	<	* @throws NullPointerException if tasks or any element are null
563	<	* @throws RuntimeException or Error if any task did so
678	>	* @param tasks the tasks
679	>	* @throws NullPointerException if any task is null
680		*/
681		public static void invokeAll(ForkJoinTask<?>... tasks) {
682		Throwable ex = null;
#	Line 573 | Line 689 | public abstract class ForkJoinTask<V> im
689		}
690		else if (i != 0)
691		t.fork();
692	<	else {
693	<	t.quietlyInvoke();
578	<	if (ex == null)
579	<	ex = t.getException();
580	<	}
692	>	else if (t.doInvoke() < NORMAL && ex == null)
693	>	ex = t.getException();
694		}
695		for (int i = 1; i <= last; ++i) {
696		ForkJoinTask<?> t = tasks[i];
697		if (t != null) {
698		if (ex != null)
699		t.cancel(false);
700	<	else {
701	<	t.quietlyJoin();
589	<	if (ex == null)
590	<	ex = t.getException();
591	<	}
700	>	else if (t.doJoin() < NORMAL && ex == null)
701	>	ex = t.getException();
702		}
703		}
704		if (ex != null)
705	<	rethrowException(ex);
705	>	UNSAFE.throwException(ex);
706		}
707
708		/**
709	<	* Forks all tasks in the collection, returning when
710	<	* {@code isDone} holds for all of them. If any task
711	<	* encounters an exception, others may be cancelled.  This method
712	<	* may be invoked only from within ForkJoinTask computations (as
713	<	* may be determined using method {@link
714	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
715	<	* in exceptions or errors, possibly including ClassCastException.
709	>	* Forks all tasks in the specified collection, returning when
710	>	* {@code isDone} holds for each task or an (unchecked) exception
711	>	* is encountered, in which case the exception is rethrown. If
712	>	* more than one task encounters an exception, then this method
713	>	* throws any one of these exceptions. If any task encounters an
714	>	* exception, others may be cancelled. However, the execution
715	>	* status of individual tasks is not guaranteed upon exceptional
716	>	* return. The status of each task may be obtained using {@link
717	>	* #getException()} and related methods to check if they have been
718	>	* cancelled, completed normally or exceptionally, or left
719	>	* unprocessed.
720	>	*
721	>	* <p>This method may be invoked only from within {@code
722	>	* ForkJoinPool} computations (as may be determined using method
723	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
724	>	* result in exceptions or errors, possibly including {@code
725	>	* ClassCastException}.
726		*
727		* @param tasks the collection of tasks
728		* @return the tasks argument, to simplify usage
729		* @throws NullPointerException if tasks or any element are null
610	–	* @throws RuntimeException or Error if any task did so
730		*/
731		public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
732	<	if (!(tasks instanceof List<?>)) {
732	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
733		invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
734		return tasks;
735		}
#	Line 627 | Line 746 | public abstract class ForkJoinTask<V> im
746		}
747		else if (i != 0)
748		t.fork();
749	<	else {
750	<	t.quietlyInvoke();
632	<	if (ex == null)
633	<	ex = t.getException();
634	<	}
749	>	else if (t.doInvoke() < NORMAL && ex == null)
750	>	ex = t.getException();
751		}
752		for (int i = 1; i <= last; ++i) {
753		ForkJoinTask<?> t = ts.get(i);
754		if (t != null) {
755		if (ex != null)
756		t.cancel(false);
757	<	else {
758	<	t.quietlyJoin();
643	<	if (ex == null)
644	<	ex = t.getException();
645	<	}
757	>	else if (t.doJoin() < NORMAL && ex == null)
758	>	ex = t.getException();
759		}
760		}
761		if (ex != null)
762	<	rethrowException(ex);
762	>	UNSAFE.throwException(ex);
763		return tasks;
764		}
765
766		/**
767	<	* Returns {@code true} if the computation performed by this task
768	<	* has completed (or has been cancelled).
769	<	*
770	<	* @return {@code true} if this computation has completed
771	<	*/
772	<	public final boolean isDone() {
773	<	return status < 0;
774	<	}
775	<
776	<	/**
664	<	* Returns {@code true} if this task was cancelled.
665	<	*
666	<	* @return {@code true} if this task was cancelled
667	<	*/
668	<	public final boolean isCancelled() {
669	<	return (status & COMPLETION_MASK) == CANCELLED;
670	<	}
671	<
672	<	/**
673	<	* Asserts that the results of this task's computation will not be
674	<	* used. If a cancellation occurs before attempting to execute this
675	<	* task, execution will be suppressed, {@link #isCancelled}
676	<	* will report true, and {@link #join} will result in a
677	<	* {@code CancellationException} being thrown. Otherwise, when
678	<	* cancellation races with completion, there are no guarantees
679	<	* about whether {@code isCancelled} will report {@code true},
680	<	* whether {@code join} will return normally or via an exception,
681	<	* or whether these behaviors will remain consistent upon repeated
682	<	* invocation.
767	>	* Attempts to cancel execution of this task. This attempt will
768	>	* fail if the task has already completed or could not be
769	>	* cancelled for some other reason. If successful, and this task
770	>	* has not started when {@code cancel} is called, execution of
771	>	* this task is suppressed. After this method returns
772	>	* successfully, unless there is an intervening call to {@link
773	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
774	>	* {@link #isDone}, and {@code cancel} will return {@code true}
775	>	* and calls to {@link #join} and related methods will result in
776	>	* {@code CancellationException}.
777		*
778		* <p>This method may be overridden in subclasses, but if so, must
779	<	* still ensure that these minimal properties hold. In particular,
780	<	* the cancel method itself must not throw exceptions.
779	>	* still ensure that these properties hold. In particular, the
780	>	* {@code cancel} method itself must not throw exceptions.
781		*
782	<	* <p> This method is designed to be invoked by <em>other</em>
782	>	* <p>This method is designed to be invoked by <em>other</em>
783		* tasks. To terminate the current task, you can just return or
784		* throw an unchecked exception from its computation method, or
785		* invoke {@link #completeExceptionally}.
786		*
787	<	* @param mayInterruptIfRunning this value is ignored in the
788	<	* default implementation because tasks are not in general
789	<	* cancelled via interruption
787	>	* @param mayInterruptIfRunning this value has no effect in the
788	>	* default implementation because interrupts are not used to
789	>	* control cancellation.
790		*
791		* @return {@code true} if this task is now cancelled
792		*/
793		public boolean cancel(boolean mayInterruptIfRunning) {
794	<	setCompletion(CANCELLED);
795	<	return (status & COMPLETION_MASK) == CANCELLED;
794	>	return setCompletion(CANCELLED) == CANCELLED;
795	>	}
796	>
797	>	/**
798	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
799	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
800	>	* exceptions, but if it does anyway, we have no recourse during
801	>	* shutdown, so guard against this case.
802	>	*/
803	>	final void cancelIgnoringExceptions() {
804	>	try {
805	>	cancel(false);
806	>	} catch (Throwable ignore) {
807	>	}
808	>	}
809	>
810	>	public final boolean isDone() {
811	>	return status < 0;
812	>	}
813	>
814	>	public final boolean isCancelled() {
815	>	return status == CANCELLED;
816		}
817
818		/**
#	Line 707 | Line 821 | public abstract class ForkJoinTask<V> im
821		* @return {@code true} if this task threw an exception or was cancelled
822		*/
823		public final boolean isCompletedAbnormally() {
824	<	return (status & COMPLETION_MASK) < NORMAL;
824	>	return status < NORMAL;
825	>	}
826	>
827	>	/**
828	>	* Returns {@code true} if this task completed without throwing an
829	>	* exception and was not cancelled.
830	>	*
831	>	* @return {@code true} if this task completed without throwing an
832	>	* exception and was not cancelled
833	>	*/
834	>	public final boolean isCompletedNormally() {
835	>	return status == NORMAL;
836		}
837
838		/**
839		* Returns the exception thrown by the base computation, or a
840	<	* CancellationException if cancelled, or null if none or if the
841	<	* method has not yet completed.
840	>	* {@code CancellationException} if cancelled, or {@code null} if
841	>	* none or if the method has not yet completed.
842		*
843		* @return the exception, or {@code null} if none
844		*/
845		public final Throwable getException() {
846	<	int s = status & COMPLETION_MASK;
847	<	if (s >= NORMAL)
848	<	return null;
849	<	if (s == CANCELLED)
725	<	return new CancellationException();
726	<	return exceptionMap.get(this);
846	>	int s = status;
847	>	return ((s >= NORMAL)    ? null :
848	>	(s == CANCELLED) ? new CancellationException() :
849	>	getThrowableException());
850		}
851
852		/**
#	Line 732 | Line 855 | public abstract class ForkJoinTask<V> im
855		* {@code join} and related operations. This method may be used
856		* to induce exceptions in asynchronous tasks, or to force
857		* completion of tasks that would not otherwise complete.  Its use
858	<	* in other situations is likely to be wrong.  This method is
858	>	* in other situations is discouraged.  This method is
859		* overridable, but overridden versions must invoke {@code super}
860		* implementation to maintain guarantees.
861		*
862	<	* @param ex the exception to throw. If this exception is
863	<	* not a RuntimeException or Error, the actual exception thrown
864	<	* will be a RuntimeException with cause ex.
862	>	* @param ex the exception to throw. If this exception is not a
863	>	* {@code RuntimeException} or {@code Error}, the actual exception
864	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
865		*/
866		public void completeExceptionally(Throwable ex) {
867	<	setDoneExceptionally((ex instanceof RuntimeException) ||
868	<	(ex instanceof Error) ? ex :
869	<	new RuntimeException(ex));
867	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
868	>	(ex instanceof Error) ? ex :
869	>	new RuntimeException(ex));
870		}
871
872		/**
873		* Completes this task, and if not already aborted or cancelled,
874	<	* returning a {@code null} result upon {@code join} and related
875	<	* operations. This method may be used to provide results for
876	<	* asynchronous tasks, or to provide alternative handling for
877	<	* tasks that would not otherwise complete normally. Its use in
878	<	* other situations is likely to be wrong. This method is
879	<	* overridable, but overridden versions must invoke {@code super}
880	<	* implementation to maintain guarantees.
874	>	* returning the given value as the result of subsequent
875	>	* invocations of {@code join} and related operations. This method
876	>	* may be used to provide results for asynchronous tasks, or to
877	>	* provide alternative handling for tasks that would not otherwise
878	>	* complete normally. Its use in other situations is
879	>	* discouraged. This method is overridable, but overridden
880	>	* versions must invoke {@code super} implementation to maintain
881	>	* guarantees.
882		*
883		* @param value the result value for this task
884		*/
#	Line 762 | Line 886 | public abstract class ForkJoinTask<V> im
886		try {
887		setRawResult(value);
888		} catch (Throwable rex) {
889	<	setDoneExceptionally(rex);
889	>	setExceptionalCompletion(rex);
890		return;
891		}
892	<	setNormalCompletion();
769	<	}
770	<
771	<	public final V get() throws InterruptedException, ExecutionException {
772	<	ForkJoinWorkerThread w = getWorker();
773	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
774	<	awaitDone(w, true);
775	<	return reportFutureResult();
776	<	}
777	<
778	<	public final V get(long timeout, TimeUnit unit)
779	<	throws InterruptedException, ExecutionException, TimeoutException {
780	<	ForkJoinWorkerThread w = getWorker();
781	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
782	<	awaitDone(w, unit.toNanos(timeout));
783	<	return reportTimedFutureResult();
892	>	setCompletion(NORMAL);
893		}
894
895		/**
896	<	* Possibly executes other tasks until this task is ready, then
897	<	* returns the result of the computation.  This method may be more
789	<	* efficient than {@code join}, but is only applicable when
790	<	* there are no potential dependencies between continuation of the
791	<	* current task and that of any other task that might be executed
792	<	* while helping. (This usually holds for pure divide-and-conquer
793	<	* tasks). This method may be invoked only from within
794	<	* ForkJoinTask computations (as may be determined using method
795	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
796	<	* result in exceptions or errors, possibly including
797	<	* ClassCastException.
896	>	* Waits if necessary for the computation to complete, and then
897	>	* retrieves its result.
898		*
899		* @return the computed result
900	+	* @throws CancellationException if the computation was cancelled
901	+	* @throws ExecutionException if the computation threw an
902	+	* exception
903	+	* @throws InterruptedException if the current thread is not a
904	+	* member of a ForkJoinPool and was interrupted while waiting
905		*/
906	<	public final V helpJoin() {
907	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
908	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
909	<	reportException(busyJoin(w));
906	>	public final V get() throws InterruptedException, ExecutionException {
907	>	int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ?
908	>	doJoin() : externalInterruptibleAwaitDone(0L);
909	>	Throwable ex;
910	>	if (s == CANCELLED)
911	>	throw new CancellationException();
912	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
913	>	throw new ExecutionException(ex);
914		return getRawResult();
915		}
916
917		/**
918	<	* Possibly executes other tasks until this task is ready.  This
919	<	* method may be invoked only from within ForkJoinTask
920	<	* computations (as may be determined using method {@link
921	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
922	<	* in exceptions or errors, possibly including ClassCastException.
918	>	* Waits if necessary for at most the given time for the computation
919	>	* to complete, and then retrieves its result, if available.
920	>	*
921	>	* @param timeout the maximum time to wait
922	>	* @param unit the time unit of the timeout argument
923	>	* @return the computed result
924	>	* @throws CancellationException if the computation was cancelled
925	>	* @throws ExecutionException if the computation threw an
926	>	* exception
927	>	* @throws InterruptedException if the current thread is not a
928	>	* member of a ForkJoinPool and was interrupted while waiting
929	>	* @throws TimeoutException if the wait timed out
930		*/
931	<	public final void quietlyHelpJoin() {
932	<	if (status >= 0) {
933	<	ForkJoinWorkerThread w =
934	<	(ForkJoinWorkerThread) Thread.currentThread();
935	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
936	<	busyJoin(w);
931	>	public final V get(long timeout, TimeUnit unit)
932	>	throws InterruptedException, ExecutionException, TimeoutException {
933	>	Thread t = Thread.currentThread();
934	>	if (t instanceof ForkJoinWorkerThread) {
935	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
936	>	long nanos = unit.toNanos(timeout);
937	>	if (status >= 0) {
938	>	boolean completed = false;
939	>	if (w.unpushTask(this)) {
940	>	try {
941	>	completed = exec();
942	>	} catch (Throwable rex) {
943	>	setExceptionalCompletion(rex);
944	>	}
945	>	}
946	>	if (completed)
947	>	setCompletion(NORMAL);
948	>	else if (status >= 0 && nanos > 0)
949	>	w.pool.timedAwaitJoin(this, nanos);
950	>	}
951	>	}
952	>	else {
953	>	long millis = unit.toMillis(timeout);
954	>	if (millis > 0)
955	>	externalInterruptibleAwaitDone(millis);
956		}
957	+	int s = status;
958	+	if (s != NORMAL) {
959	+	Throwable ex;
960	+	if (s == CANCELLED)
961	+	throw new CancellationException();
962	+	if (s != EXCEPTIONAL)
963	+	throw new TimeoutException();
964	+	if ((ex = getThrowableException()) != null)
965	+	throw new ExecutionException(ex);
966	+	}
967	+	return getRawResult();
968		}
969
970		/**
971	<	* Joins this task, without returning its result or throwing an
971	>	* Joins this task, without returning its result or throwing its
972		* exception. This method may be useful when processing
973		* collections of tasks when some have been cancelled or otherwise
974		* known to have aborted.
975		*/
976		public final void quietlyJoin() {
977	<	if (status >= 0) {
832	<	ForkJoinWorkerThread w = getWorker();
833	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
834	<	awaitDone(w, true);
835	<	}
977	>	doJoin();
978		}
979
980		/**
981		* Commences performing this task and awaits its completion if
982	<	* necessary, without returning its result or throwing an
983	<	* exception. This method may be useful when processing
842	<	* collections of tasks when some have been cancelled or otherwise
843	<	* known to have aborted.
982	>	* necessary, without returning its result or throwing its
983	>	* exception.
984		*/
985		public final void quietlyInvoke() {
986	<	if (status >= 0 && !tryQuietlyInvoke())
847	<	quietlyJoin();
986	>	doInvoke();
987		}
988
989		/**
990		* Possibly executes tasks until the pool hosting the current task
991	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
992	<	* designs in which many tasks are forked, but none are explicitly
993	<	* joined, instead executing them until all are processed.
991	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
992	>	* be of use in designs in which many tasks are forked, but none
993	>	* are explicitly joined, instead executing them until all are
994	>	* processed.
995	>	*
996	>	* <p>This method may be invoked only from within {@code
997	>	* ForkJoinPool} computations (as may be determined using method
998	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
999	>	* result in exceptions or errors, possibly including {@code
1000	>	* ClassCastException}.
1001		*/
1002		public static void helpQuiesce() {
1003		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 864 | Line 1010 | public abstract class ForkJoinTask<V> im
1010		* this task, but only if reuse occurs when this task has either
1011		* never been forked, or has been forked, then completed and all
1012		* outstanding joins of this task have also completed. Effects
1013	<	* under any other usage conditions are not guaranteed, and are
1014	<	* almost surely wrong. This method may be useful when executing
1013	>	* under any other usage conditions are not guaranteed.
1014	>	* This method may be useful when executing
1015		* pre-constructed trees of subtasks in loops.
1016	+	*
1017	+	* <p>Upon completion of this method, {@code isDone()} reports
1018	+	* {@code false}, and {@code getException()} reports {@code
1019	+	* null}. However, the value returned by {@code getRawResult} is
1020	+	* unaffected. To clear this value, you can invoke {@code
1021	+	* setRawResult(null)}.
1022		*/
1023		public void reinitialize() {
1024	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
1025	<	exceptionMap.remove(this);
1026	<	status = 0;
1024	>	if (status == EXCEPTIONAL)
1025	>	clearExceptionalCompletion();
1026	>	else
1027	>	status = 0;
1028		}
1029
1030		/**
1031		* Returns the pool hosting the current task execution, or null
1032		* if this task is executing outside of any ForkJoinPool.
1033		*
1034	+	* @see #inForkJoinPool
1035		* @return the pool, or {@code null} if none
1036		*/
1037		public static ForkJoinPool getPool() {
#	Line 887 | Line 1041 | public abstract class ForkJoinTask<V> im
1041		}
1042
1043		/**
1044	<	* Returns {@code true} if the current thread is executing as a
1045	<	* ForkJoinPool computation.
1044	>	* Returns {@code true} if the current thread is a {@link
1045	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
1046		*
1047	<	* @return {@code true} if the current thread is executing as a
1048	<	* ForkJoinPool computation, or false otherwise
1047	>	* @return {@code true} if the current thread is a {@link
1048	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
1049	>	* or {@code false} otherwise
1050		*/
1051		public static boolean inForkJoinPool() {
1052		return Thread.currentThread() instanceof ForkJoinWorkerThread;
#	Line 903 | Line 1058 | public abstract class ForkJoinTask<V> im
1058		* by the current thread, and has not commenced executing in
1059		* another thread.  This method may be useful when arranging
1060		* alternative local processing of tasks that could have been, but
1061	<	* were not, stolen. This method may be invoked only from within
1062	<	* ForkJoinTask computations (as may be determined using method
1063	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1064	<	* result in exceptions or errors, possibly including
1065	<	* ClassCastException.
1061	>	* were not, stolen.
1062	>	*
1063	>	* <p>This method may be invoked only from within {@code
1064	>	* ForkJoinPool} computations (as may be determined using method
1065	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1066	>	* result in exceptions or errors, possibly including {@code
1067	>	* ClassCastException}.
1068		*
1069		* @return {@code true} if unforked
1070		*/
#	Line 922 | Line 1079 | public abstract class ForkJoinTask<V> im
1079		* value may be useful for heuristic decisions about whether to
1080		* fork other tasks.
1081		*
1082	+	* <p>This method may be invoked only from within {@code
1083	+	* ForkJoinPool} computations (as may be determined using method
1084	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1085	+	* result in exceptions or errors, possibly including {@code
1086	+	* ClassCastException}.
1087	+	*
1088		* @return the number of tasks
1089		*/
1090		public static int getQueuedTaskCount() {
#	Line 939 | Line 1102 | public abstract class ForkJoinTask<V> im
1102		* tasks, and to process computations locally if this threshold is
1103		* exceeded.
1104		*
1105	+	* <p>This method may be invoked only from within {@code
1106	+	* ForkJoinPool} computations (as may be determined using method
1107	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1108	+	* result in exceptions or errors, possibly including {@code
1109	+	* ClassCastException}.
1110	+	*
1111		* @return the surplus number of tasks, which may be negative
1112		*/
1113		public static int getSurplusQueuedTaskCount() {
#	Line 974 | Line 1143 | public abstract class ForkJoinTask<V> im
1143		* called otherwise. The return value controls whether this task
1144		* is considered to be done normally. It may return false in
1145		* asynchronous actions that require explicit invocations of
1146	<	* {@link #complete} to become joinable. It may throw exceptions
1147	<	* to indicate abnormal exit.
1146	>	* {@link #complete} to become joinable. It may also throw an
1147	>	* (unchecked) exception to indicate abnormal exit.
1148		*
1149		* @return {@code true} if completed normally
981	–	* @throws Error or RuntimeException if encountered during computation
1150		*/
1151		protected abstract boolean exec();
1152
1153		/**
1154	<	* Returns, but does not unschedule or execute, the task queued by
1155	<	* the current thread but not yet executed, if one is
1154	>	* Returns, but does not unschedule or execute, a task queued by
1155	>	* the current thread but not yet executed, if one is immediately
1156		* available. There is no guarantee that this task will actually
1157	<	* be polled or executed next.  This method is designed primarily
1158	<	* to support extensions, and is unlikely to be useful otherwise.
1159	<	* This method may be invoked only from within ForkJoinTask
1160	<	* computations (as may be determined using method {@link
1161	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
1162	<	* in exceptions or errors, possibly including ClassCastException.
1157	>	* be polled or executed next. Conversely, this method may return
1158	>	* null even if a task exists but cannot be accessed without
1159	>	* contention with other threads.  This method is designed
1160	>	* primarily to support extensions, and is unlikely to be useful
1161	>	* otherwise.
1162	>	*
1163	>	* <p>This method may be invoked only from within {@code
1164	>	* ForkJoinPool} computations (as may be determined using method
1165	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1166	>	* result in exceptions or errors, possibly including {@code
1167	>	* ClassCastException}.
1168		*
1169		* @return the next task, or {@code null} if none are available
1170		*/
#	Line 1004 | Line 1177 | public abstract class ForkJoinTask<V> im
1177		* Unschedules and returns, without executing, the next task
1178		* queued by the current thread but not yet executed.  This method
1179		* is designed primarily to support extensions, and is unlikely to
1180	<	* be useful otherwise.  This method may be invoked only from
1181	<	* within ForkJoinTask computations (as may be determined using
1182	<	* method {@link #inForkJoinPool}). Attempts to invoke in other
1183	<	* contexts result in exceptions or errors, possibly including
1184	<	* ClassCastException.
1180	>	* be useful otherwise.
1181	>	*
1182	>	* <p>This method may be invoked only from within {@code
1183	>	* ForkJoinPool} computations (as may be determined using method
1184	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1185	>	* result in exceptions or errors, possibly including {@code
1186	>	* ClassCastException}.
1187		*
1188		* @return the next task, or {@code null} if none are available
1189		*/
#	Line 1025 | Line 1200 | public abstract class ForkJoinTask<V> im
1200		* {@code null} result does not necessarily imply quiescence
1201		* of the pool this task is operating in.  This method is designed
1202		* primarily to support extensions, and is unlikely to be useful
1203	<	* otherwise.  This method may be invoked only from within
1204	<	* ForkJoinTask computations (as may be determined using method
1205	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1206	<	* result in exceptions or errors, possibly including
1207	<	* ClassCastException.
1203	>	* otherwise.
1204	>	*
1205	>	* <p>This method may be invoked only from within {@code
1206	>	* ForkJoinPool} computations (as may be determined using method
1207	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1208	>	* result in exceptions or errors, possibly including {@code
1209	>	* ClassCastException}.
1210		*
1211		* @return a task, or {@code null} if none are available
1212		*/
#	Line 1038 | Line 1215 | public abstract class ForkJoinTask<V> im
1215		.pollTask();
1216		}
1217
1218	<	// adaptors
1218	>	/**
1219	>	* Adaptor for Runnables. This implements RunnableFuture
1220	>	* to be compliant with AbstractExecutorService constraints
1221	>	* when used in ForkJoinPool.
1222	>	*/
1223	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1224	>	implements RunnableFuture<T> {
1225	>	final Runnable runnable;
1226	>	final T resultOnCompletion;
1227	>	T result;
1228	>	AdaptedRunnable(Runnable runnable, T result) {
1229	>	if (runnable == null) throw new NullPointerException();
1230	>	this.runnable = runnable;
1231	>	this.resultOnCompletion = result;
1232	>	}
1233	>	public T getRawResult() { return result; }
1234	>	public void setRawResult(T v) { result = v; }
1235	>	public boolean exec() {
1236	>	runnable.run();
1237	>	result = resultOnCompletion;
1238	>	return true;
1239	>	}
1240	>	public void run() { invoke(); }
1241	>	private static final long serialVersionUID = 5232453952276885070L;
1242	>	}
1243
1244		/**
1245	<	* Returns a new ForkJoinTask that performs the {@code run}
1246	<	* method of the given Runnable as its action, and returns a null
1247	<	* result upon {@code join}.
1245	>	* Adaptor for Callables
1246	>	*/
1247	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1248	>	implements RunnableFuture<T> {
1249	>	final Callable<? extends T> callable;
1250	>	T result;
1251	>	AdaptedCallable(Callable<? extends T> callable) {
1252	>	if (callable == null) throw new NullPointerException();
1253	>	this.callable = callable;
1254	>	}
1255	>	public T getRawResult() { return result; }
1256	>	public void setRawResult(T v) { result = v; }
1257	>	public boolean exec() {
1258	>	try {
1259	>	result = callable.call();
1260	>	return true;
1261	>	} catch (Error err) {
1262	>	throw err;
1263	>	} catch (RuntimeException rex) {
1264	>	throw rex;
1265	>	} catch (Exception ex) {
1266	>	throw new RuntimeException(ex);
1267	>	}
1268	>	}
1269	>	public void run() { invoke(); }
1270	>	private static final long serialVersionUID = 2838392045355241008L;
1271	>	}
1272	>
1273	>	/**
1274	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1275	>	* method of the given {@code Runnable} as its action, and returns
1276	>	* a null result upon {@link #join}.
1277		*
1278		* @param runnable the runnable action
1279		* @return the task
1280		*/
1281	<	public static ForkJoinTask<Void> adapt(Runnable runnable) {
1282	<	return new ForkJoinPool.AdaptedRunnable<Void>(runnable, null);
1281	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1282	>	return new AdaptedRunnable<Void>(runnable, null);
1283		}
1284
1285		/**
1286	<	* Returns a new ForkJoinTask that performs the {@code run}
1287	<	* method of the given Runnable as its action, and returns the
1288	<	* given result upon {@code join}.
1286	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1287	>	* method of the given {@code Runnable} as its action, and returns
1288	>	* the given result upon {@link #join}.
1289		*
1290		* @param runnable the runnable action
1291		* @param result the result upon completion
1292		* @return the task
1293		*/
1294		public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1295	<	return new ForkJoinPool.AdaptedRunnable<T>(runnable, result);
1295	>	return new AdaptedRunnable<T>(runnable, result);
1296		}
1297
1298		/**
1299	<	* Returns a new ForkJoinTask that performs the {@code call}
1300	<	* method of the given Callable as its action, and returns its
1301	<	* result upon {@code join}, translating any checked
1302	<	* exceptions encountered into {@code RuntimeException}.
1299	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1300	>	* method of the given {@code Callable} as its action, and returns
1301	>	* its result upon {@link #join}, translating any checked exceptions
1302	>	* encountered into {@code RuntimeException}.
1303		*
1304		* @param callable the callable action
1305		* @return the task
1306		*/
1307	<	public static <T> ForkJoinTask<T> adapt(Callable<T> callable) {
1308	<	return new ForkJoinPool.AdaptedCallable<T>(callable);
1307	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1308	>	return new AdaptedCallable<T>(callable);
1309		}
1310
1311		// Serialization support
#	Line 1083 | Line 1313 | public abstract class ForkJoinTask<V> im
1313		private static final long serialVersionUID = -7721805057305804111L;
1314
1315		/**
1316	<	* Save the state to a stream.
1316	>	* Saves the state to a stream (that is, serializes it).
1317		*
1318		* @serialData the current run status and the exception thrown
1319		* during execution, or {@code null} if none
#	Line 1096 | Line 1326 | public abstract class ForkJoinTask<V> im
1326		}
1327
1328		/**
1329	<	* Reconstitute the instance from a stream.
1329	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1330		*
1331		* @param s the stream
1332		*/
1333		private void readObject(java.io.ObjectInputStream s)
1334		throws java.io.IOException, ClassNotFoundException {
1335		s.defaultReadObject();
1106	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1107	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1336		Object ex = s.readObject();
1337		if (ex != null)
1338	<	setDoneExceptionally((Throwable) ex);
1338	>	setExceptionalCompletion((Throwable)ex);
1339		}
1340
1341		// Unsafe mechanics
1342	<
1343	<	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1344	<	private static final long statusOffset =
1345	<	objectFieldOffset("status", ForkJoinTask.class);
1346	<
1347	<	private static long objectFieldOffset(String field, Class<?> klazz) {
1342	>	private static final sun.misc.Unsafe UNSAFE;
1343	>	private static final long statusOffset;
1344	>	static {
1345	>	exceptionTableLock = new ReentrantLock();
1346	>	exceptionTableRefQueue = new ReferenceQueue<Object>();
1347	>	exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY];
1348		try {
1349	<	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1350	<	} catch (NoSuchFieldException e) {
1351	<	// Convert Exception to corresponding Error
1352	<	NoSuchFieldError error = new NoSuchFieldError(field);
1353	<	error.initCause(e);
1126	<	throw error;
1349	>	UNSAFE = getUnsafe();
1350	>	statusOffset = UNSAFE.objectFieldOffset
1351	>	(ForkJoinTask.class.getDeclaredField("status"));
1352	>	} catch (Exception e) {
1353	>	throw new Error(e);
1354		}
1355		}
1356

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