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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.18 by dl, Sat Jul 25 15:50:57 2009 UTC vs.
Revision 1.69 by dl, Mon Nov 22 12:24:34 2010 UTC

#	Line 6 | Line 6
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;
16	+	import java.util.concurrent.Callable;
17	+	import java.util.concurrent.CancellationException;
18	+	import java.util.concurrent.ExecutionException;
19	+	import java.util.concurrent.Executor;
20	+	import java.util.concurrent.ExecutorService;
21	+	import java.util.concurrent.Future;
22	+	import java.util.concurrent.RejectedExecutionException;
23	+	import java.util.concurrent.RunnableFuture;
24	+	import java.util.concurrent.TimeUnit;
25	+	import java.util.concurrent.TimeoutException;
26
27		/**
28	<	* Abstract base class for tasks that run within a {@link
29	<	* ForkJoinPool}.  A ForkJoinTask is a thread-like entity that is much
28	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
29	>	* A {@code ForkJoinTask} is a thread-like entity that is much
30		* lighter weight than a normal thread.  Huge numbers of tasks and
31		* subtasks may be hosted by a small number of actual threads in a
32		* ForkJoinPool, at the price of some usage limitations.
33		*
34	<	* <p> A "main" ForkJoinTask begins execution when submitted to a
35	<	* {@link ForkJoinPool}. Once started, it will usually in turn start
36	<	* other subtasks.  As indicated by the name of this class, many
37	<	* programs using ForkJoinTasks employ only methods {@code fork}
38	<	* and {@code join}, or derivatives such as
39	<	* {@code invokeAll}.  However, this class also provides a number
40	<	* of other methods that can come into play in advanced usages, as
41	<	* well as extension mechanics that allow support of new forms of
42	<	* fork/join processing.
34	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
35	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
36	>	* start other subtasks.  As indicated by the name of this class,
37	>	* many programs using {@code ForkJoinTask} employ only methods
38	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
39	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
40	>	* provides a number of other methods that can come into play in
41	>	* advanced usages, as well as extension mechanics that allow
42	>	* support of new forms of fork/join processing.
43		*
44	<	* <p>A ForkJoinTask is a lightweight form of {@link Future}.  The
45	<	* efficiency of ForkJoinTasks stems from a set of restrictions (that
46	<	* are only partially statically enforceable) reflecting their
47	<	* intended use as computational tasks calculating pure functions or
48	<	* operating on purely isolated objects.  The primary coordination
49	<	* mechanisms are {@link #fork}, that arranges asynchronous execution,
50	<	* and {@link #join}, that doesn't proceed until the task's result has
51	<	* been computed.  Computations should avoid {@code synchronized}
52	<	* methods or blocks, and should minimize other blocking
53	<	* synchronization apart from joining other tasks or using
54	<	* synchronizers such as Phasers that are advertised to cooperate with
55	<	* fork/join scheduling. Tasks should also not perform blocking IO,
56	<	* and should ideally access variables that are completely independent
57	<	* of those accessed by other running tasks. Minor breaches of these
58	<	* restrictions, for example using shared output streams, may be
59	<	* tolerable in practice, but frequent use may result in poor
60	<	* performance, and the potential to indefinitely stall if the number
61	<	* of threads not waiting for IO or other external synchronization
62	<	* becomes exhausted. This usage restriction is in part enforced by
63	<	* not permitting checked exceptions such as {@code IOExceptions}
64	<	* to be thrown. However, computations may still encounter unchecked
65	<	* exceptions, that are rethrown to callers attempting join
66	<	* them. These exceptions may additionally include
67	<	* RejectedExecutionExceptions stemming from internal resource
68	<	* exhaustion such as failure to allocate internal task queues.
44	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
45	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
46	>	* restrictions (that are only partially statically enforceable)
47	>	* reflecting their intended use as computational tasks calculating
48	>	* pure functions or operating on purely isolated objects.  The
49	>	* primary coordination mechanisms are {@link #fork}, that arranges
50	>	* asynchronous execution, and {@link #join}, that doesn't proceed
51	>	* until the task's result has been computed.  Computations should
52	>	* avoid {@code synchronized} methods or blocks, and should minimize
53	>	* other blocking synchronization apart from joining other tasks or
54	>	* using synchronizers such as Phasers that are advertised to
55	>	* cooperate with fork/join scheduling. Tasks should also not perform
56	>	* blocking IO, and should ideally access variables that are
57	>	* completely independent of those accessed by other running
58	>	* tasks. Minor breaches of these restrictions, for example using
59	>	* shared output streams, may be tolerable in practice, but frequent
60	>	* use may result in poor performance, and the potential to
61	>	* indefinitely stall if the number of threads not waiting for IO or
62	>	* other external synchronization becomes exhausted. This usage
63	>	* restriction is in part enforced by not permitting checked
64	>	* exceptions such as {@code IOExceptions} to be thrown. However,
65	>	* computations may still encounter unchecked exceptions, that are
66	>	* rethrown to callers attempting to join them. These exceptions may
67	>	* additionally include {@link RejectedExecutionException} stemming
68	>	* from internal resource exhaustion, such as failure to allocate
69	>	* internal task queues.
70		*
71		* <p>The primary method for awaiting completion and extracting
72		* results of a task is {@link #join}, but there are several variants:
73		* The {@link Future#get} methods support interruptible and/or timed
74		* waits for completion and report results using {@code Future}
75	<	* conventions. Method {@link #helpJoin} enables callers to actively
76	<	* execute other tasks while awaiting joins, which is sometimes more
77	<	* efficient but only applies when all subtasks are known to be
78	<	* 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
75	>	* conventions. Method {@link #invoke} is semantically
76	>	* equivalent to {@code fork(); join()} but always attempts to begin
77	>	* execution in the current thread. The "<em>quiet</em>" forms of
78	>	* these methods do not extract results or report exceptions. These
79		* may be useful when a set of tasks are being executed, and you need
80		* to delay processing of results or exceptions until all complete.
81		* Method {@code invokeAll} (available in multiple versions)
82		* performs the most common form of parallel invocation: forking a set
83		* of tasks and joining them all.
84		*
85	<	* <p> The ForkJoinTask class is not usually directly subclassed.
85	>	* <p>The execution status of tasks may be queried at several levels
86	>	* of detail: {@link #isDone} is true if a task completed in any way
87	>	* (including the case where a task was cancelled without executing);
88	>	* {@link #isCompletedNormally} is true if a task completed without
89	>	* cancellation or encountering an exception; {@link #isCancelled} is
90	>	* true if the task was cancelled (in which case {@link #getException}
91	>	* returns a {@link java.util.concurrent.CancellationException}); and
92	>	* {@link #isCompletedAbnormally} is true if a task was either
93	>	* cancelled or encountered an exception, in which case {@link
94	>	* #getException} will return either the encountered exception or
95	>	* {@link java.util.concurrent.CancellationException}.
96	>	*
97	>	* <p>The ForkJoinTask class is not usually directly subclassed.
98		* Instead, you subclass one of the abstract classes that support a
99	<	* particular style of fork/join processing.  Normally, a concrete
99	>	* particular style of fork/join processing, typically {@link
100	>	* RecursiveAction} for computations that do not return results, or
101	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
102		* ForkJoinTask subclass declares fields comprising its parameters,
103		* established in a constructor, and then defines a {@code compute}
104		* method that somehow uses the control methods supplied by this base
105		* class. While these methods have {@code public} access (to allow
106	<	* instances of different task subclasses to call each others
106	>	* instances of different task subclasses to call each other's
107		* methods), some of them may only be called from within other
108		* ForkJoinTasks (as may be determined using method {@link
109		* #inForkJoinPool}).  Attempts to invoke them in other contexts
110		* result in exceptions or errors, possibly including
111	<	* ClassCastException.
111	>	* {@code ClassCastException}.
112	>	*
113	>	* <p>Method {@link #join} and its variants are appropriate for use
114	>	* only when completion dependencies are acyclic; that is, the
115	>	* parallel computation can be described as a directed acyclic graph
116	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
117	>	* tasks cyclically wait for each other.  However, this framework
118	>	* supports other methods and techniques (for example the use of
119	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
120	>	* may be of use in constructing custom subclasses for problems that
121	>	* are not statically structured as DAGs.
122		*
123	<	* <p>Most base support methods are {@code final} because their
124	<	* implementations are intrinsically tied to the underlying
125	<	* lightweight task scheduling framework, and so cannot be overridden.
126	<	* Developers creating new basic styles of fork/join processing should
127	<	* minimally implement {@code protected} methods
128	<	* {@code exec}, {@code setRawResult}, and
129	<	* {@code getRawResult}, while also introducing an abstract
130	<	* computational method that can be implemented in its subclasses,
131	<	* possibly relying on other {@code protected} methods provided
101	<	* by this class.
123	>	* <p>Most base support methods are {@code final}, to prevent
124	>	* overriding of implementations that are intrinsically tied to the
125	>	* underlying lightweight task scheduling framework.  Developers
126	>	* creating new basic styles of fork/join processing should minimally
127	>	* implement {@code protected} methods {@link #exec}, {@link
128	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
129	>	* an abstract computational method that can be implemented in its
130	>	* subclasses, possibly relying on other {@code protected} methods
131	>	* provided by this class.
132		*
133		* <p>ForkJoinTasks should perform relatively small amounts of
134	<	* computations, otherwise splitting into smaller tasks. As a very
135	<	* rough rule of thumb, a task should perform more than 100 and less
136	<	* than 10000 basic computational steps. If tasks are too big, then
137	<	* parallelism cannot improve throughput. If too small, then memory
138	<	* and internal task maintenance overhead may overwhelm processing.
134	>	* computation. Large tasks should be split into smaller subtasks,
135	>	* usually via recursive decomposition. As a very rough rule of thumb,
136	>	* a task should perform more than 100 and less than 10000 basic
137	>	* computational steps. If tasks are too big, then parallelism cannot
138	>	* improve throughput. If too small, then memory and internal task
139	>	* maintenance overhead may overwhelm processing.
140		*
141	<	* <p>ForkJoinTasks are {@code Serializable}, which enables them
142	<	* to be used in extensions such as remote execution frameworks. It is
143	<	* in general sensible to serialize tasks only before or after, but
144	<	* not during execution. Serialization is not relied on during
145	<	* execution itself.
141	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
142	>	* and {@link Callable}, that may be of use when mixing execution of
143	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
144	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
145	>	*
146	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
147	>	* used in extensions such as remote execution frameworks. It is
148	>	* sensible to serialize tasks only before or after, but not during,
149	>	* execution. Serialization is not relied on during execution itself.
150		*
151		* @since 1.7
152		* @author Doug Lea
153		*/
154		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
155
156	<	/**
157	<	* Run control status bits packed into a single int to minimize
158	<	* footprint and to ensure atomicity (via CAS).  Status is
159	<	* initially zero, and takes on nonnegative values until
160	<	* completed, upon which status holds COMPLETED. CANCELLED, or
161	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
162	<	* blocking waits by other threads have SIGNAL_MASK bits set --
163	<	* bit 15 for external (nonFJ) waits, and the rest a count of
164	<	* waiting FJ threads.  (This representation relies on
165	<	* ForkJoinPool max thread limits). Completion of a stolen task
166	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
167	<	* though suboptimal for some purposes, we use basic builtin
168	<	* wait/notify to take advantage of "monitor inflation" in JVMs
169	<	* that we would otherwise need to emulate to avoid adding further
170	<	* per-task bookkeeping overhead. Note that bits 16-28 are
171	<	* currently unused. Also value 0x80000000 is available as spare
172	<	* completion value.
156	>	/*
157	>	* See the internal documentation of class ForkJoinPool for a
158	>	* general implementation overview.  ForkJoinTasks are mainly
159	>	* responsible for maintaining their "status" field amidst relays
160	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
161	>	* methods of this class are more-or-less layered into (1) basic
162	>	* status maintenance (2) execution and awaiting completion (3)
163	>	* user-level methods that additionally report results. This is
164	>	* sometimes hard to see because this file orders exported methods
165	>	* in a way that flows well in javadocs. In particular, most
166	>	* join mechanics are in method quietlyJoin, below.
167	>	*/
168	>
169	>	/*
170	>	* The status field holds run control status bits packed into a
171	>	* single int to minimize footprint and to ensure atomicity (via
172	>	* CAS).  Status is initially zero, and takes on nonnegative
173	>	* values until completed, upon which status holds value
174	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
175	>	* waits by other threads have the SIGNAL bit set.  Completion of
176	>	* a stolen task with SIGNAL set awakens any waiters via
177	>	* notifyAll. Even though suboptimal for some purposes, we use
178	>	* basic builtin wait/notify to take advantage of "monitor
179	>	* inflation" in JVMs that we would otherwise need to emulate to
180	>	* avoid adding further per-task bookkeeping overhead.  We want
181	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
182	>	* techniques, so use some odd coding idioms that tend to avoid
183	>	* them.
184		*/
185	+
186	+	/** The run status of this task */
187		volatile int status; // accessed directly by pool and workers
188
189	<	static final int COMPLETION_MASK      = 0xe0000000;
190	<	static final int NORMAL               = 0xe0000000; // == mask
191	<	static final int CANCELLED            = 0xc0000000;
192	<	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
189	>	private static final int NORMAL      = -1;
190	>	private static final int CANCELLED   = -2;
191	>	private static final int EXCEPTIONAL = -3;
192	>	private static final int SIGNAL      =  1;
193
194		/**
195		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 158 | Line 203 | public abstract class ForkJoinTask<V> im
203		Collections.synchronizedMap
204		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
205
206	<	// 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	<	}
206	>	// Maintaining completion status
207
208		/**
209	<	* Workaround for not being able to rethrow unchecked exceptions.
210	<	*/
179	<	static void rethrowException(Throwable ex) {
180	<	if (ex != null)
181	<	UNSAFE.throwException(ex);
182	<	}
183	<
184	<	// Setting completion status
185	<
186	<	/**
187	<	* Marks completion and wakes up threads waiting to join this task.
209	>	* Marks completion and wakes up threads waiting to join this task,
210	>	* also clearing signal request bits.
211		*
212		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
213		*/
214	<	final void setCompletion(int completion) {
215	<	ForkJoinPool pool = getPool();
216	<	if (pool != null) {
217	<	int s; // Clear signal bits while setting completion status
218	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
219	<
220	<	if ((s & SIGNAL_MASK) != 0) {
198	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
199	<	pool.updateRunningCount(s);
200	<	synchronized (this) { notifyAll(); }
214	>	private void setCompletion(int completion) {
215	>	int s;
216	>	while ((s = status) >= 0) {
217	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
218	>	if (s != 0)
219	>	synchronized (this) { notifyAll(); }
220	>	break;
221		}
222		}
203	–	else
204	–	externallySetCompletion(completion);
223		}
224
225		/**
226	<	* Version of setCompletion for non-FJ threads.  Leaves signal
227	<	* bits for unblocked threads to adjust, and always notifies.
228	<	*/
211	<	private void externallySetCompletion(int completion) {
212	<	int s;
213	<	do {} while ((s = status) >= 0 &&
214	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
215	<	synchronized (this) { notifyAll(); }
216	<	}
217	<
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.
226	>	* Records exception and sets exceptional completion.
227	>	*
228	>	* @return status on exit
229		*/
230	<	private void doAwaitDone() {
231	<	// Minimize lock bias and in/de-flation effects by maximizing
232	<	// 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	<	}
230	>	private void setExceptionalCompletion(Throwable rex) {
231	>	exceptionMap.put(this, rex);
232	>	setCompletion(EXCEPTIONAL);
233		}
234
235		/**
236	<	* Performs the actual timed monitor wait for awaitDone.
236	>	* Blocks a worker thread until completion. Called only by
237	>	* pool. Currently unused -- pool-based waits use timeout
238	>	* version below.
239		*/
240	<	private void doAwaitDone(long startTime, long nanos) {
241	<	synchronized (this) {
240	>	final void internalAwaitDone() {
241	>	int s;         // the odd construction reduces lock bias effects
242	>	while ((s = status) >= 0) {
243		try {
244	<	while (status >= 0) {
245	<	long nt = nanos - System.nanoTime() - startTime;
246	<	if (nt <= 0)
253	<	break;
254	<	wait(nt / 1000000, (int) (nt % 1000000));
244	>	synchronized (this) {
245	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
246	>	wait();
247		}
248		} catch (InterruptedException ie) {
249	<	onInterruptedWait();
249	>	cancelIfTerminating();
250		}
251		}
252		}
253
262	–	// Awaiting completion
263	–
264	–	/**
265	–	* Sets status to indicate there is joiner, then waits for join,
266	–	* surrounded with pool notifications.
267	–	*
268	–	* @return status upon exit
269	–	*/
270	–	private int awaitDone(ForkJoinWorkerThread w,
271	–	boolean maintainParallelism) {
272	–	ForkJoinPool pool = (w == null) ? null : w.pool;
273	–	int s;
274	–	while ((s = status) >= 0) {
275	–	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
276	–	if (pool == null || !pool.preJoin(this, maintainParallelism))
277	–	doAwaitDone();
278	–	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
279	–	adjustPoolCountsOnUnblock(pool);
280	–	break;
281	–	}
282	–	}
283	–	return s;
284	–	}
285	–
254		/**
255	<	* Timed version of awaitDone
255	>	* Blocks a worker thread until completed or timed out.  Called
256	>	* only by pool.
257		*
258	<	* @return status upon exit
258	>	* @return status on exit
259		*/
260	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
292	<	ForkJoinPool pool = (w == null) ? null : w.pool;
260	>	final int internalAwaitDone(long millis, int nanos) {
261		int s;
262	<	while ((s = status) >= 0) {
263	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
264	<	long startTime = System.nanoTime();
265	<	if (pool == null || !pool.preJoin(this, false))
266	<	doAwaitDone(startTime, nanos);
299	<	if ((s = status) >= 0) {
300	<	adjustPoolCountsOnCancelledWait(pool);
301	<	s = status;
262	>	if ((s = status) >= 0) {
263	>	try {
264	>	synchronized (this) {
265	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
266	>	wait(millis, nanos);
267		}
268	<	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
269	<	adjustPoolCountsOnUnblock(pool);
305	<	break;
268	>	} catch (InterruptedException ie) {
269	>	cancelIfTerminating();
270		}
271	+	s = status;
272		}
273		return s;
274		}
275
276		/**
277	<	* Notifies pool that thread is unblocked. Called by signalled
313	<	* threads when woken by non-FJ threads (which is atypical).
277	>	* Blocks a non-worker-thread until completion.
278		*/
279	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
279	>	private void externalAwaitDone() {
280		int s;
281	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
282	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
283	<	pool.updateRunningCount(s);
284	<	}
285	<
286	<	/**
287	<	* Notifies pool to adjust counts on cancelled or timed out wait.
288	<	*/
289	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
290	<	if (pool != null) {
291	<	int s;
292	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
293	<	if (casStatus(s, s - 1)) {
330	<	pool.updateRunningCount(1);
281	>	while ((s = status) >= 0) {
282	>	synchronized (this) {
283	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
284	>	boolean interrupted = false;
285	>	while (status >= 0) {
286	>	try {
287	>	wait();
288	>	} catch (InterruptedException ie) {
289	>	interrupted = true;
290	>	}
291	>	}
292	>	if (interrupted)
293	>	Thread.currentThread().interrupt();
294		break;
295		}
296		}
#	Line 335 | Line 298 | public abstract class ForkJoinTask<V> im
298		}
299
300		/**
301	<	* Handles interruptions during waits.
302	<	*/
303	<	private void onInterruptedWait() {
341	<	ForkJoinWorkerThread w = getWorker();
342	<	if (w == null)
343	<	Thread.currentThread().interrupt(); // re-interrupt
344	<	else if (w.isTerminating())
345	<	cancelIgnoringExceptions();
346	<	// else if FJworker, ignore interrupt
347	<	}
348	<
349	<	// Recording and reporting exceptions
350	<
351	<	private void setDoneExceptionally(Throwable rex) {
352	<	exceptionMap.put(this, rex);
353	<	setCompletion(EXCEPTIONAL);
354	<	}
355	<
356	<	/**
357	<	* Throws the exception associated with status s.
358	<	*
359	<	* @throws the exception
360	<	*/
361	<	private void reportException(int s) {
362	<	if ((s &= COMPLETION_MASK) < NORMAL) {
363	<	if (s == CANCELLED)
364	<	throw new CancellationException();
365	<	else
366	<	rethrowException(exceptionMap.get(this));
367	<	}
368	<	}
369	<
370	<	/**
371	<	* Returns result or throws exception using j.u.c.Future conventions.
372	<	* Only call when {@code isDone} known to be true.
373	<	*/
374	<	private V reportFutureResult()
375	<	throws ExecutionException, InterruptedException {
376	<	int s = status & COMPLETION_MASK;
377	<	if (s < NORMAL) {
378	<	Throwable ex;
379	<	if (s == CANCELLED)
380	<	throw new CancellationException();
381	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
382	<	throw new ExecutionException(ex);
383	<	if (Thread.interrupted())
384	<	throw new InterruptedException();
385	<	}
386	<	return getRawResult();
387	<	}
388	<
389	<	/**
390	<	* Returns result or throws exception using j.u.c.Future conventions
391	<	* with timeouts.
392	<	*/
393	<	private V reportTimedFutureResult()
394	<	throws InterruptedException, ExecutionException, TimeoutException {
395	<	Throwable ex;
396	<	int s = status & COMPLETION_MASK;
397	<	if (s == NORMAL)
398	<	return getRawResult();
399	<	if (s == CANCELLED)
400	<	throw new CancellationException();
401	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
402	<	throw new ExecutionException(ex);
403	<	if (Thread.interrupted())
404	<	throw new InterruptedException();
405	<	throw new TimeoutException();
406	<	}
407	<
408	<	// internal execution methods
409	<
410	<	/**
411	<	* Calls exec, recording completion, and rethrowing exception if
412	<	* encountered. Caller should normally check status before calling.
413	<	*
414	<	* @return true if completed normally
415	<	*/
416	<	private boolean tryExec() {
417	<	try { // try block must contain only call to exec
418	<	if (!exec())
419	<	return false;
420	<	} catch (Throwable rex) {
421	<	setDoneExceptionally(rex);
422	<	rethrowException(rex);
423	<	return false; // not reached
424	<	}
425	<	setNormalCompletion();
426	<	return true;
427	<	}
428	<
429	<	/**
430	<	* Main execution method used by worker threads. Invokes
431	<	* base computation unless already complete.
301	>	* Unless done, calls exec and records status if completed, but
302	>	* doesn't wait for completion otherwise. Primary execution method
303	>	* for ForkJoinWorkerThread.
304		*/
305		final void quietlyExec() {
434	–	if (status >= 0) {
435	–	try {
436	–	if (!exec())
437	–	return;
438	–	} catch (Throwable rex) {
439	–	setDoneExceptionally(rex);
440	–	return;
441	–	}
442	–	setNormalCompletion();
443	–	}
444	–	}
445	–
446	–	/**
447	–	* Calls exec(), recording but not rethrowing exception.
448	–	* Caller should normally check status before calling.
449	–	*
450	–	* @return true if completed normally
451	–	*/
452	–	private boolean tryQuietlyInvoke() {
306		try {
307	<	if (!exec())
308	<	return false;
307	>	if (status < 0 || !exec())
308	>	return;
309		} catch (Throwable rex) {
310	<	setDoneExceptionally(rex);
311	<	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) {
310	>	setExceptionalCompletion(rex);
311	>	return;
312		}
313	<	}
473	<
474	<	/**
475	<	* Main implementation of helpJoin
476	<	*/
477	<	private int busyJoin(ForkJoinWorkerThread w) {
478	<	int s;
479	<	ForkJoinTask<?> t;
480	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
481	<	t.quietlyExec();
482	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
313	>	setCompletion(NORMAL); // must be outside try block
314		}
315
316		// public methods
#	Line 487 | Line 318 | public abstract class ForkJoinTask<V> im
318		/**
319		* Arranges to asynchronously execute this task.  While it is not
320		* necessarily enforced, it is a usage error to fork a task more
321	<	* than once unless it has completed and been reinitialized.  This
322	<	* method may be invoked only from within ForkJoinTask
323	<	* computations (as may be determined using method {@link
324	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
325	<	* in exceptions or errors, possibly including ClassCastException.
321	>	* than once unless it has completed and been reinitialized.
322	>	* Subsequent modifications to the state of this task or any data
323	>	* it operates on are not necessarily consistently observable by
324	>	* any thread other than the one executing it unless preceded by a
325	>	* call to {@link #join} or related methods, or a call to {@link
326	>	* #isDone} returning {@code true}.
327	>	*
328	>	* <p>This method may be invoked only from within {@code
329	>	* ForkJoinTask} computations (as may be determined using method
330	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
331	>	* result in exceptions or errors, possibly including {@code
332	>	* ClassCastException}.
333		*
334	<	* @return <code>this</code>, to simplify usage.
334	>	* @return {@code this}, to simplify usage
335		*/
336		public final ForkJoinTask<V> fork() {
337		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 502 | Line 340 | public abstract class ForkJoinTask<V> im
340		}
341
342		/**
343	<	* Returns the result of the computation when it is ready.
344	<	* This method differs from {@code get} in that abnormal
345	<	* completion results in RuntimeExceptions or Errors, not
346	<	* ExecutionExceptions.
343	>	* Returns the result of the computation when it {@link #isDone is
344	>	* done}.  This method differs from {@link #get()} in that
345	>	* abnormal completion results in {@code RuntimeException} or
346	>	* {@code Error}, not {@code ExecutionException}, and that
347	>	* interrupts of the calling thread do <em>not</em> cause the
348	>	* method to abruptly return by throwing {@code
349	>	* InterruptedException}.
350		*
351		* @return the computed result
352		*/
353		public final V join() {
354	<	ForkJoinWorkerThread w = getWorker();
355	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
356	<	reportException(awaitDone(w, true));
354	>	quietlyJoin();
355	>	Throwable ex;
356	>	if (status < NORMAL && (ex = getException()) != null)
357	>	UNSAFE.throwException(ex);
358		return getRawResult();
359		}
360
361		/**
362		* Commences performing this task, awaits its completion if
363	<	* necessary, and return its result.
363	>	* necessary, and returns its result, or throws an (unchecked)
364	>	* {@code RuntimeException} or {@code Error} if the underlying
365	>	* computation did so.
366		*
523	–	* @throws Throwable (a RuntimeException, Error, or unchecked
524	–	* exception) if the underlying computation did so
367		* @return the computed result
368		*/
369		public final V invoke() {
370	<	if (status >= 0 && tryExec())
371	<	return getRawResult();
372	<	else
373	<	return join();
370	>	quietlyInvoke();
371	>	Throwable ex;
372	>	if (status < NORMAL && (ex = getException()) != null)
373	>	UNSAFE.throwException(ex);
374	>	return getRawResult();
375		}
376
377		/**
378	<	* Forks both tasks, returning when {@code isDone} holds for
379	<	* both of them or an exception is encountered. This method may be
380	<	* invoked only from within ForkJoinTask computations (as may be
381	<	* determined using method {@link #inForkJoinPool}). Attempts to
382	<	* invoke in other contexts result in exceptions or errors,
383	<	* possibly including ClassCastException.
384	<	*
385	<	* @param t1 one task
386	<	* @param t2 the other task
387	<	* @throws NullPointerException if t1 or t2 are null
388	<	* @throws RuntimeException or Error if either task did so
378	>	* Forks the given tasks, returning when {@code isDone} holds for
379	>	* each task or an (unchecked) exception is encountered, in which
380	>	* case the exception is rethrown. If more than one task
381	>	* encounters an exception, then this method throws any one of
382	>	* these exceptions. If any task encounters an exception, the
383	>	* other may be cancelled. However, the execution status of
384	>	* individual tasks is not guaranteed upon exceptional return. The
385	>	* status of each task may be obtained using {@link
386	>	* #getException()} and related methods to check if they have been
387	>	* cancelled, completed normally or exceptionally, or left
388	>	* unprocessed.
389	>	*
390	>	* <p>This method may be invoked only from within {@code
391	>	* ForkJoinPool} computations (as may be determined using method
392	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
393	>	* result in exceptions or errors, possibly including {@code
394	>	* ClassCastException}.
395	>	*
396	>	* @param t1 the first task
397	>	* @param t2 the second task
398	>	* @throws NullPointerException if any task is null
399		*/
400	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
400	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
401		t2.fork();
402		t1.invoke();
403		t2.join();
404		}
405
406		/**
407	<	* Forks the given tasks, returning when {@code isDone} holds
408	<	* for all of them. If any task encounters an exception, others
409	<	* may be cancelled.  This method may be invoked only from within
410	<	* ForkJoinTask computations (as may be determined using method
411	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
412	<	* result in exceptions or errors, possibly including
413	<	* ClassCastException.
407	>	* Forks the given tasks, returning when {@code isDone} holds for
408	>	* each task or an (unchecked) exception is encountered, in which
409	>	* case the exception is rethrown. If more than one task
410	>	* encounters an exception, then this method throws any one of
411	>	* these exceptions. If any task encounters an exception, others
412	>	* may be cancelled. However, the execution status of individual
413	>	* tasks is not guaranteed upon exceptional return. The status of
414	>	* each task may be obtained using {@link #getException()} and
415	>	* related methods to check if they have been cancelled, completed
416	>	* normally or exceptionally, or left unprocessed.
417	>	*
418	>	* <p>This method may be invoked only from within {@code
419	>	* ForkJoinPool} computations (as may be determined using method
420	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
421	>	* result in exceptions or errors, possibly including {@code
422	>	* ClassCastException}.
423		*
424	<	* @param tasks the array of tasks
425	<	* @throws NullPointerException if tasks or any element are null
564	<	* @throws RuntimeException or Error if any task did so
424	>	* @param tasks the tasks
425	>	* @throws NullPointerException if any task is null
426		*/
427		public static void invokeAll(ForkJoinTask<?>... tasks) {
428		Throwable ex = null;
#	Line 576 | Line 437 | public abstract class ForkJoinTask<V> im
437		t.fork();
438		else {
439		t.quietlyInvoke();
440	<	if (ex == null)
440	>	if (ex == null && t.status < NORMAL)
441		ex = t.getException();
442		}
443		}
#	Line 587 | Line 448 | public abstract class ForkJoinTask<V> im
448		t.cancel(false);
449		else {
450		t.quietlyJoin();
451	<	if (ex == null)
451	>	if (ex == null && t.status < NORMAL)
452		ex = t.getException();
453		}
454		}
455		}
456		if (ex != null)
457	<	rethrowException(ex);
457	>	UNSAFE.throwException(ex);
458		}
459
460		/**
461	<	* Forks all tasks in the collection, returning when
462	<	* {@code isDone} holds for all of them. If any task
463	<	* encounters an exception, others may be cancelled.  This method
464	<	* may be invoked only from within ForkJoinTask computations (as
465	<	* may be determined using method {@link
466	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
467	<	* in exceptions or errors, possibly including ClassCastException.
461	>	* Forks all tasks in the specified collection, returning when
462	>	* {@code isDone} holds for each task or an (unchecked) exception
463	>	* is encountered, in which case the exception is rethrown. If
464	>	* more than one task encounters an exception, then this method
465	>	* throws any one of these exceptions. If any task encounters an
466	>	* exception, others may be cancelled. However, the execution
467	>	* status of individual tasks is not guaranteed upon exceptional
468	>	* return. The status of each task may be obtained using {@link
469	>	* #getException()} and related methods to check if they have been
470	>	* cancelled, completed normally or exceptionally, or left
471	>	* unprocessed.
472	>	*
473	>	* <p>This method may be invoked only from within {@code
474	>	* ForkJoinPool} computations (as may be determined using method
475	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
476	>	* result in exceptions or errors, possibly including {@code
477	>	* ClassCastException}.
478		*
479		* @param tasks the collection of tasks
480	+	* @return the tasks argument, to simplify usage
481		* @throws NullPointerException if tasks or any element are null
610	–	* @throws RuntimeException or Error if any task did so
482		*/
483	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
484	<	if (!(tasks instanceof List<?>)) {
483	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
484	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
485		invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
486	<	return;
486	>	return tasks;
487		}
488		@SuppressWarnings("unchecked")
489		List<? extends ForkJoinTask<?>> ts =
#	Line 629 | Line 500 | public abstract class ForkJoinTask<V> im
500		t.fork();
501		else {
502		t.quietlyInvoke();
503	<	if (ex == null)
503	>	if (ex == null && t.status < NORMAL)
504		ex = t.getException();
505		}
506		}
#	Line 640 | Line 511 | public abstract class ForkJoinTask<V> im
511		t.cancel(false);
512		else {
513		t.quietlyJoin();
514	<	if (ex == null)
514	>	if (ex == null && t.status < NORMAL)
515		ex = t.getException();
516		}
517		}
518		}
519		if (ex != null)
520	<	rethrowException(ex);
520	>	UNSAFE.throwException(ex);
521	>	return tasks;
522		}
523
524		/**
525	<	* Returns true if the computation performed by this task has
526	<	* completed (or has been cancelled).
525	>	* Attempts to cancel execution of this task. This attempt will
526	>	* fail if the task has already completed or could not be
527	>	* cancelled for some other reason. If successful, and this task
528	>	* has not started when {@code cancel} is called, execution of
529	>	* this task is suppressed. After this method returns
530	>	* successfully, unless there is an intervening call to {@link
531	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
532	>	* {@link #isDone}, and {@code cancel} will return {@code true}
533	>	* and calls to {@link #join} and related methods will result in
534	>	* {@code CancellationException}.
535	>	*
536	>	* <p>This method may be overridden in subclasses, but if so, must
537	>	* still ensure that these properties hold. In particular, the
538	>	* {@code cancel} method itself must not throw exceptions.
539	>	*
540	>	* <p>This method is designed to be invoked by <em>other</em>
541	>	* tasks. To terminate the current task, you can just return or
542	>	* throw an unchecked exception from its computation method, or
543	>	* invoke {@link #completeExceptionally}.
544	>	*
545	>	* @param mayInterruptIfRunning this value has no effect in the
546	>	* default implementation because interrupts are not used to
547	>	* control cancellation.
548		*
549	<	* @return true if this computation has completed
549	>	* @return {@code true} if this task is now cancelled
550		*/
551	<	public final boolean isDone() {
552	<	return status < 0;
551	>	public boolean cancel(boolean mayInterruptIfRunning) {
552	>	setCompletion(CANCELLED);
553	>	return status == CANCELLED;
554		}
555
556		/**
557	<	* Returns true if this task was cancelled.
558	<	*
559	<	* @return true if this task was cancelled
557	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
558	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
559	>	* exceptions, but if it does anyway, we have no recourse during
560	>	* shutdown, so guard against this case.
561		*/
562	+	final void cancelIgnoringExceptions() {
563	+	try {
564	+	cancel(false);
565	+	} catch (Throwable ignore) {
566	+	}
567	+	}
568	+
569	+	/**
570	+	* Cancels if current thread is a terminating worker thread,
571	+	* ignoring any exceptions thrown by cancel.
572	+	*/
573	+	final void cancelIfTerminating() {
574	+	Thread t = Thread.currentThread();
575	+	if ((t instanceof ForkJoinWorkerThread) &&
576	+	((ForkJoinWorkerThread) t).isTerminating()) {
577	+	try {
578	+	cancel(false);
579	+	} catch (Throwable ignore) {
580	+	}
581	+	}
582	+	}
583	+
584	+	public final boolean isDone() {
585	+	return status < 0;
586	+	}
587	+
588		public final boolean isCancelled() {
589	<	return (status & COMPLETION_MASK) == CANCELLED;
589	>	return status == CANCELLED;
590		}
591
592		/**
593	<	* Asserts that the results of this task's computation will not be
673	<	* used. If a cancellation occurs before attempting to execute this
674	<	* task, then execution will be suppressed, {@code isCancelled}
675	<	* will report true, and {@code join} will result in a
676	<	* {@code CancellationException} being thrown. Otherwise, when
677	<	* cancellation races with completion, there are no guarantees
678	<	* about whether {@code isCancelled} will report true, whether
679	<	* {@code join} will return normally or via an exception, or
680	<	* whether these behaviors will remain consistent upon repeated
681	<	* invocation.
682	<	*
683	<	* <p>This method may be overridden in subclasses, but if so, must
684	<	* still ensure that these minimal properties hold. In particular,
685	<	* the cancel method itself must not throw exceptions.
593	>	* Returns {@code true} if this task threw an exception or was cancelled.
594		*
595	<	* <p> This method is designed to be invoked by <em>other</em>
688	<	* tasks. To terminate the current task, you can just return or
689	<	* throw an unchecked exception from its computation method, or
690	<	* invoke {@code completeExceptionally}.
691	<	*
692	<	* @param mayInterruptIfRunning this value is ignored in the
693	<	* default implementation because tasks are not in general
694	<	* cancelled via interruption
695	<	*
696	<	* @return true if this task is now cancelled
595	>	* @return {@code true} if this task threw an exception or was cancelled
596		*/
597	<	public boolean cancel(boolean mayInterruptIfRunning) {
598	<	setCompletion(CANCELLED);
700	<	return (status & COMPLETION_MASK) == CANCELLED;
597	>	public final boolean isCompletedAbnormally() {
598	>	return status < NORMAL;
599		}
600
601		/**
602	<	* Returns true if this task threw an exception or was cancelled.
602	>	* Returns {@code true} if this task completed without throwing an
603	>	* exception and was not cancelled.
604		*
605	<	* @return true if this task threw an exception or was cancelled
605	>	* @return {@code true} if this task completed without throwing an
606	>	* exception and was not cancelled
607		*/
608	<	public final boolean isCompletedAbnormally() {
609	<	return (status & COMPLETION_MASK) < NORMAL;
608	>	public final boolean isCompletedNormally() {
609	>	return status == NORMAL;
610		}
611
612		/**
613		* Returns the exception thrown by the base computation, or a
614	<	* CancellationException if cancelled, or null if none or if the
615	<	* method has not yet completed.
614	>	* {@code CancellationException} if cancelled, or {@code null} if
615	>	* none or if the method has not yet completed.
616		*
617	<	* @return the exception, or null if none
617	>	* @return the exception, or {@code null} if none
618		*/
619		public final Throwable getException() {
620	<	int s = status & COMPLETION_MASK;
621	<	if (s >= NORMAL)
622	<	return null;
623	<	if (s == CANCELLED)
724	<	return new CancellationException();
725	<	return exceptionMap.get(this);
620	>	int s = status;
621	>	return ((s >= NORMAL)    ? null :
622	>	(s == CANCELLED) ? new CancellationException() :
623	>	exceptionMap.get(this));
624		}
625
626		/**
#	Line 731 | Line 629 | public abstract class ForkJoinTask<V> im
629		* {@code join} and related operations. This method may be used
630		* to induce exceptions in asynchronous tasks, or to force
631		* completion of tasks that would not otherwise complete.  Its use
632	<	* in other situations is likely to be wrong.  This method is
632	>	* in other situations is discouraged.  This method is
633		* overridable, but overridden versions must invoke {@code super}
634		* implementation to maintain guarantees.
635		*
636	<	* @param ex the exception to throw. If this exception is
637	<	* not a RuntimeException or Error, the actual exception thrown
638	<	* will be a RuntimeException with cause ex.
636	>	* @param ex the exception to throw. If this exception is not a
637	>	* {@code RuntimeException} or {@code Error}, the actual exception
638	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
639		*/
640		public void completeExceptionally(Throwable ex) {
641	<	setDoneExceptionally((ex instanceof RuntimeException) ||
642	<	(ex instanceof Error) ? ex :
643	<	new RuntimeException(ex));
641	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
642	>	(ex instanceof Error) ? ex :
643	>	new RuntimeException(ex));
644		}
645
646		/**
647		* Completes this task, and if not already aborted or cancelled,
648	<	* returning a {@code null} result upon {@code join} and related
649	<	* operations. This method may be used to provide results for
650	<	* asynchronous tasks, or to provide alternative handling for
651	<	* tasks that would not otherwise complete normally. Its use in
652	<	* other situations is likely to be wrong. This method is
653	<	* overridable, but overridden versions must invoke {@code super}
654	<	* implementation to maintain guarantees.
648	>	* returning the given value as the result of subsequent
649	>	* invocations of {@code join} and related operations. This method
650	>	* may be used to provide results for asynchronous tasks, or to
651	>	* provide alternative handling for tasks that would not otherwise
652	>	* complete normally. Its use in other situations is
653	>	* discouraged. This method is overridable, but overridden
654	>	* versions must invoke {@code super} implementation to maintain
655	>	* guarantees.
656		*
657		* @param value the result value for this task
658		*/
#	Line 761 | Line 660 | public abstract class ForkJoinTask<V> im
660		try {
661		setRawResult(value);
662		} catch (Throwable rex) {
663	<	setDoneExceptionally(rex);
663	>	setExceptionalCompletion(rex);
664		return;
665		}
666	<	setNormalCompletion();
768	<	}
769	<
770	<	public final V get() throws InterruptedException, ExecutionException {
771	<	ForkJoinWorkerThread w = getWorker();
772	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
773	<	awaitDone(w, true);
774	<	return reportFutureResult();
775	<	}
776	<
777	<	public final V get(long timeout, TimeUnit unit)
778	<	throws InterruptedException, ExecutionException, TimeoutException {
779	<	ForkJoinWorkerThread w = getWorker();
780	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
781	<	awaitDone(w, unit.toNanos(timeout));
782	<	return reportTimedFutureResult();
666	>	setCompletion(NORMAL);
667		}
668
669		/**
670	<	* Possibly executes other tasks until this task is ready, then
671	<	* returns the result of the computation.  This method may be more
788	<	* efficient than {@code join}, but is only applicable when
789	<	* there are no potential dependencies between continuation of the
790	<	* current task and that of any other task that might be executed
791	<	* while helping. (This usually holds for pure divide-and-conquer
792	<	* tasks). This method may be invoked only from within
793	<	* ForkJoinTask computations (as may be determined using method
794	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
795	<	* result in exceptions or errors, possibly including
796	<	* ClassCastException.
670	>	* Waits if necessary for the computation to complete, and then
671	>	* retrieves its result.
672		*
673		* @return the computed result
674	+	* @throws CancellationException if the computation was cancelled
675	+	* @throws ExecutionException if the computation threw an
676	+	* exception
677	+	* @throws InterruptedException if the current thread is not a
678	+	* member of a ForkJoinPool and was interrupted while waiting
679		*/
680	<	public final V helpJoin() {
681	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
682	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
683	<	reportException(busyJoin(w));
680	>	public final V get() throws InterruptedException, ExecutionException {
681	>	int s;
682	>	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
683	>	quietlyJoin();
684	>	s = status;
685	>	}
686	>	else {
687	>	while ((s = status) >= 0) {
688	>	synchronized (this) { // interruptible form of awaitDone
689	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
690	>	s, SIGNAL)) {
691	>	while (status >= 0)
692	>	wait();
693	>	}
694	>	}
695	>	}
696	>	}
697	>	if (s < NORMAL) {
698	>	Throwable ex;
699	>	if (s == CANCELLED)
700	>	throw new CancellationException();
701	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
702	>	throw new ExecutionException(ex);
703	>	}
704		return getRawResult();
705		}
706
707		/**
708	<	* Possibly executes other tasks until this task is ready.  This
709	<	* method may be invoked only from within ForkJoinTask
710	<	* computations (as may be determined using method {@link
711	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
712	<	* in exceptions or errors, possibly including ClassCastException.
708	>	* Waits if necessary for at most the given time for the computation
709	>	* to complete, and then retrieves its result, if available.
710	>	*
711	>	* @param timeout the maximum time to wait
712	>	* @param unit the time unit of the timeout argument
713	>	* @return the computed result
714	>	* @throws CancellationException if the computation was cancelled
715	>	* @throws ExecutionException if the computation threw an
716	>	* exception
717	>	* @throws InterruptedException if the current thread is not a
718	>	* member of a ForkJoinPool and was interrupted while waiting
719	>	* @throws TimeoutException if the wait timed out
720		*/
721	<	public final void quietlyHelpJoin() {
721	>	public final V get(long timeout, TimeUnit unit)
722	>	throws InterruptedException, ExecutionException, TimeoutException {
723	>	long nanos = unit.toNanos(timeout);
724		if (status >= 0) {
725	<	ForkJoinWorkerThread w =
726	<	(ForkJoinWorkerThread) Thread.currentThread();
727	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
728	<	busyJoin(w);
725	>	Thread t = Thread.currentThread();
726	>	if (t instanceof ForkJoinWorkerThread) {
727	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
728	>	boolean completed = false; // timed variant of quietlyJoin
729	>	if (w.unpushTask(this)) {
730	>	try {
731	>	completed = exec();
732	>	} catch (Throwable rex) {
733	>	setExceptionalCompletion(rex);
734	>	}
735	>	}
736	>	if (completed)
737	>	setCompletion(NORMAL);
738	>	else if (status >= 0)
739	>	w.joinTask(this, true, nanos);
740	>	}
741	>	else if (Thread.interrupted())
742	>	throw new InterruptedException();
743	>	else {
744	>	long startTime = System.nanoTime();
745	>	int s; long nt;
746	>	while ((s = status) >= 0 &&
747	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
748	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,
749	>	SIGNAL)) {
750	>	long ms = nt / 1000000;
751	>	int ns = (int) (nt % 1000000);
752	>	synchronized (this) {
753	>	if (status >= 0)
754	>	wait(ms, ns); // exit on IE throw
755	>	}
756	>	}
757	>	}
758	>	}
759	>	}
760	>	int es = status;
761	>	if (es != NORMAL) {
762	>	Throwable ex;
763	>	if (es == CANCELLED)
764	>	throw new CancellationException();
765	>	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
766	>	throw new ExecutionException(ex);
767	>	throw new TimeoutException();
768		}
769	+	return getRawResult();
770		}
771
772		/**
773	<	* Joins this task, without returning its result or throwing an
773	>	* Joins this task, without returning its result or throwing its
774		* exception. This method may be useful when processing
775		* collections of tasks when some have been cancelled or otherwise
776		* known to have aborted.
777		*/
778		public final void quietlyJoin() {
779	<	if (status >= 0) {
780	<	ForkJoinWorkerThread w = getWorker();
781	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
782	<	awaitDone(w, true);
779	>	Thread t;
780	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
781	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
782	>	if (status >= 0) {
783	>	if (w.unpushTask(this)) {
784	>	boolean completed;
785	>	try {
786	>	completed = exec();
787	>	} catch (Throwable rex) {
788	>	setExceptionalCompletion(rex);
789	>	return;
790	>	}
791	>	if (completed) {
792	>	setCompletion(NORMAL);
793	>	return;
794	>	}
795	>	}
796	>	w.joinTask(this, false, 0L);
797	>	}
798		}
799	+	else
800	+	externalAwaitDone();
801		}
802
803		/**
804		* Commences performing this task and awaits its completion if
805	<	* necessary, without returning its result or throwing an
806	<	* exception. This method may be useful when processing
841	<	* collections of tasks when some have been cancelled or otherwise
842	<	* known to have aborted.
805	>	* necessary, without returning its result or throwing its
806	>	* exception.
807		*/
808		public final void quietlyInvoke() {
809	<	if (status >= 0 && !tryQuietlyInvoke())
810	<	quietlyJoin();
809	>	if (status >= 0) {
810	>	boolean completed;
811	>	try {
812	>	completed = exec();
813	>	} catch (Throwable rex) {
814	>	setExceptionalCompletion(rex);
815	>	return;
816	>	}
817	>	if (completed)
818	>	setCompletion(NORMAL);
819	>	else
820	>	quietlyJoin();
821	>	}
822		}
823
824		/**
825		* Possibly executes tasks until the pool hosting the current task
826	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
827	<	* designs in which many tasks are forked, but none are explicitly
828	<	* joined, instead executing them until all are processed.
826	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
827	>	* be of use in designs in which many tasks are forked, but none
828	>	* are explicitly joined, instead executing them until all are
829	>	* processed.
830	>	*
831	>	* <p>This method may be invoked only from within {@code
832	>	* ForkJoinPool} computations (as may be determined using method
833	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
834	>	* result in exceptions or errors, possibly including {@code
835	>	* ClassCastException}.
836		*/
837		public static void helpQuiesce() {
838		((ForkJoinWorkerThread) Thread.currentThread())
#	Line 863 | Line 845 | public abstract class ForkJoinTask<V> im
845		* this task, but only if reuse occurs when this task has either
846		* never been forked, or has been forked, then completed and all
847		* outstanding joins of this task have also completed. Effects
848	<	* under any other usage conditions are not guaranteed, and are
849	<	* almost surely wrong. This method may be useful when executing
848	>	* under any other usage conditions are not guaranteed.
849	>	* This method may be useful when executing
850		* pre-constructed trees of subtasks in loops.
851	+	*
852	+	* <p>Upon completion of this method, {@code isDone()} reports
853	+	* {@code false}, and {@code getException()} reports {@code
854	+	* null}. However, the value returned by {@code getRawResult} is
855	+	* unaffected. To clear this value, you can invoke {@code
856	+	* setRawResult(null)}.
857		*/
858		public void reinitialize() {
859	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
859	>	if (status == EXCEPTIONAL)
860		exceptionMap.remove(this);
861		status = 0;
862		}
#	Line 877 | Line 865 | public abstract class ForkJoinTask<V> im
865		* Returns the pool hosting the current task execution, or null
866		* if this task is executing outside of any ForkJoinPool.
867		*
868	<	* @return the pool, or null if none
868	>	* @see #inForkJoinPool
869	>	* @return the pool, or {@code null} if none
870		*/
871		public static ForkJoinPool getPool() {
872		Thread t = Thread.currentThread();
#	Line 902 | Line 891 | public abstract class ForkJoinTask<V> im
891		* by the current thread, and has not commenced executing in
892		* another thread.  This method may be useful when arranging
893		* alternative local processing of tasks that could have been, but
894	<	* were not, stolen. This method may be invoked only from within
906	<	* ForkJoinTask computations (as may be determined using method
907	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
908	<	* result in exceptions or errors, possibly including
909	<	* ClassCastException.
894	>	* were not, stolen.
895		*
896	<	* @return true if unforked
896	>	* <p>This method may be invoked only from within {@code
897	>	* ForkJoinPool} computations (as may be determined using method
898	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
899	>	* result in exceptions or errors, possibly including {@code
900	>	* ClassCastException}.
901	>	*
902	>	* @return {@code true} if unforked
903		*/
904		public boolean tryUnfork() {
905		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 921 | Line 912 | public abstract class ForkJoinTask<V> im
912		* value may be useful for heuristic decisions about whether to
913		* fork other tasks.
914		*
915	+	* <p>This method may be invoked only from within {@code
916	+	* ForkJoinPool} computations (as may be determined using method
917	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
918	+	* result in exceptions or errors, possibly including {@code
919	+	* ClassCastException}.
920	+	*
921		* @return the number of tasks
922		*/
923		public static int getQueuedTaskCount() {
#	Line 938 | Line 935 | public abstract class ForkJoinTask<V> im
935		* tasks, and to process computations locally if this threshold is
936		* exceeded.
937		*
938	+	* <p>This method may be invoked only from within {@code
939	+	* ForkJoinPool} computations (as may be determined using method
940	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
941	+	* result in exceptions or errors, possibly including {@code
942	+	* ClassCastException}.
943	+	*
944		* @return the surplus number of tasks, which may be negative
945		*/
946		public static int getSurplusQueuedTaskCount() {
#	Line 948 | Line 951 | public abstract class ForkJoinTask<V> im
951		// Extension methods
952
953		/**
954	<	* Returns the result that would be returned by {@code join},
955	<	* even if this task completed abnormally, or null if this task is
956	<	* not known to have been completed.  This method is designed to
957	<	* aid debugging, as well as to support extensions. Its use in any
958	<	* other context is discouraged.
954	>	* Returns the result that would be returned by {@link #join}, even
955	>	* if this task completed abnormally, or {@code null} if this task
956	>	* is not known to have been completed.  This method is designed
957	>	* to aid debugging, as well as to support extensions. Its use in
958	>	* any other context is discouraged.
959		*
960	<	* @return the result, or null if not completed
960	>	* @return the result, or {@code null} if not completed
961		*/
962		public abstract V getRawResult();
963
#	Line 973 | Line 976 | public abstract class ForkJoinTask<V> im
976		* called otherwise. The return value controls whether this task
977		* is considered to be done normally. It may return false in
978		* asynchronous actions that require explicit invocations of
979	<	* {@code complete} to become joinable. It may throw exceptions
980	<	* to indicate abnormal exit.
979	>	* {@link #complete} to become joinable. It may also throw an
980	>	* (unchecked) exception to indicate abnormal exit.
981		*
982	<	* @return true if completed normally
980	<	* @throws Error or RuntimeException if encountered during computation
982	>	* @return {@code true} if completed normally
983		*/
984		protected abstract boolean exec();
985
986		/**
987	<	* Returns, but does not unschedule or execute, the task queued by
988	<	* the current thread but not yet executed, if one is
987	>	* Returns, but does not unschedule or execute, a task queued by
988	>	* the current thread but not yet executed, if one is immediately
989		* available. There is no guarantee that this task will actually
990	<	* be polled or executed next.  This method is designed primarily
991	<	* to support extensions, and is unlikely to be useful otherwise.
992	<	* This method may be invoked only from within ForkJoinTask
993	<	* computations (as may be determined using method {@link
994	<	* #inForkJoinPool}). Attempts to invoke in other contexts result
993	<	* in exceptions or errors, possibly including ClassCastException.
990	>	* be polled or executed next. Conversely, this method may return
991	>	* null even if a task exists but cannot be accessed without
992	>	* contention with other threads.  This method is designed
993	>	* primarily to support extensions, and is unlikely to be useful
994	>	* otherwise.
995		*
996	<	* @return the next task, or null if none are available
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	>	* @return the next task, or {@code null} if none are available
1003		*/
1004		protected static ForkJoinTask<?> peekNextLocalTask() {
1005		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 1003 | Line 1010 | public abstract class ForkJoinTask<V> im
1010		* Unschedules and returns, without executing, the next task
1011		* queued by the current thread but not yet executed.  This method
1012		* is designed primarily to support extensions, and is unlikely to
1013	<	* be useful otherwise.  This method may be invoked only from
1014	<	* within ForkJoinTask computations (as may be determined using
1015	<	* method {@link #inForkJoinPool}). Attempts to invoke in other
1016	<	* contexts result in exceptions or errors, possibly including
1017	<	* ClassCastException.
1013	>	* be useful otherwise.
1014	>	*
1015	>	* <p>This method may be invoked only from within {@code
1016	>	* ForkJoinPool} computations (as may be determined using method
1017	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1018	>	* result in exceptions or errors, possibly including {@code
1019	>	* ClassCastException}.
1020		*
1021	<	* @return the next task, or null if none are available
1021	>	* @return the next task, or {@code null} if none are available
1022		*/
1023		protected static ForkJoinTask<?> pollNextLocalTask() {
1024		return ((ForkJoinWorkerThread) Thread.currentThread())
#	Line 1024 | Line 1033 | public abstract class ForkJoinTask<V> im
1033		* {@code null} result does not necessarily imply quiescence
1034		* of the pool this task is operating in.  This method is designed
1035		* primarily to support extensions, and is unlikely to be useful
1036	<	* otherwise.  This method may be invoked only from within
1028	<	* ForkJoinTask computations (as may be determined using method
1029	<	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1030	<	* result in exceptions or errors, possibly including
1031	<	* ClassCastException.
1036	>	* otherwise.
1037		*
1038	<	* @return a task, or null if none are available
1038	>	* <p>This method may be invoked only from within {@code
1039	>	* ForkJoinPool} computations (as may be determined using method
1040	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1041	>	* result in exceptions or errors, possibly including {@code
1042	>	* ClassCastException}.
1043	>	*
1044	>	* @return a task, or {@code null} if none are available
1045		*/
1046		protected static ForkJoinTask<?> pollTask() {
1047		return ((ForkJoinWorkerThread) Thread.currentThread())
1048		.pollTask();
1049		}
1050
1051	<	// adaptors
1051	>	/**
1052	>	* Adaptor for Runnables. This implements RunnableFuture
1053	>	* to be compliant with AbstractExecutorService constraints
1054	>	* when used in ForkJoinPool.
1055	>	*/
1056	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1057	>	implements RunnableFuture<T> {
1058	>	final Runnable runnable;
1059	>	final T resultOnCompletion;
1060	>	T result;
1061	>	AdaptedRunnable(Runnable runnable, T result) {
1062	>	if (runnable == null) throw new NullPointerException();
1063	>	this.runnable = runnable;
1064	>	this.resultOnCompletion = result;
1065	>	}
1066	>	public T getRawResult() { return result; }
1067	>	public void setRawResult(T v) { result = v; }
1068	>	public boolean exec() {
1069	>	runnable.run();
1070	>	result = resultOnCompletion;
1071	>	return true;
1072	>	}
1073	>	public void run() { invoke(); }
1074	>	private static final long serialVersionUID = 5232453952276885070L;
1075	>	}
1076	>
1077	>	/**
1078	>	* Adaptor for Callables
1079	>	*/
1080	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1081	>	implements RunnableFuture<T> {
1082	>	final Callable<? extends T> callable;
1083	>	T result;
1084	>	AdaptedCallable(Callable<? extends T> callable) {
1085	>	if (callable == null) throw new NullPointerException();
1086	>	this.callable = callable;
1087	>	}
1088	>	public T getRawResult() { return result; }
1089	>	public void setRawResult(T v) { result = v; }
1090	>	public boolean exec() {
1091	>	try {
1092	>	result = callable.call();
1093	>	return true;
1094	>	} catch (Error err) {
1095	>	throw err;
1096	>	} catch (RuntimeException rex) {
1097	>	throw rex;
1098	>	} catch (Exception ex) {
1099	>	throw new RuntimeException(ex);
1100	>	}
1101	>	}
1102	>	public void run() { invoke(); }
1103	>	private static final long serialVersionUID = 2838392045355241008L;
1104	>	}
1105
1106		/**
1107	<	* Returns a new ForkJoinTask that performs the <code>run</code>
1108	<	* method of the given Runnable as its action, and returns a null
1109	<	* result upon <code>join</code>.
1107	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1108	>	* method of the given {@code Runnable} as its action, and returns
1109	>	* a null result upon {@link #join}.
1110		*
1111		* @param runnable the runnable action
1112		* @return the task
1113		*/
1114	<	public static ForkJoinTask<Void> adapt(Runnable runnable) {
1115	<	return new ForkJoinPool.AdaptedRunnable<Void>(runnable, null);
1114	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1115	>	return new AdaptedRunnable<Void>(runnable, null);
1116		}
1117
1118		/**
1119	<	* Returns a new ForkJoinTask that performs the <code>run</code>
1120	<	* method of the given Runnable as its action, and returns the
1121	<	* given result upon <code>join</code>.
1119	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1120	>	* method of the given {@code Runnable} as its action, and returns
1121	>	* the given result upon {@link #join}.
1122		*
1123		* @param runnable the runnable action
1124		* @param result the result upon completion
1125		* @return the task
1126		*/
1127		public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1128	<	return new ForkJoinPool.AdaptedRunnable<T>(runnable, result);
1128	>	return new AdaptedRunnable<T>(runnable, result);
1129		}
1130
1131		/**
1132	<	* Returns a new ForkJoinTask that performs the <code>call</code>
1133	<	* method of the given Callable as its action, and returns its
1134	<	* result upon <code>join</code>, translating any checked
1135	<	* exceptions encountered into <code>RuntimeException<code>.
1132	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1133	>	* method of the given {@code Callable} as its action, and returns
1134	>	* its result upon {@link #join}, translating any checked exceptions
1135	>	* encountered into {@code RuntimeException}.
1136		*
1137		* @param callable the callable action
1138		* @return the task
1139		*/
1140	<	public static <T> ForkJoinTask<T> adapt(Callable<T> callable) {
1141	<	return new ForkJoinPool.AdaptedCallable<T>(callable);
1140	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1141	>	return new AdaptedCallable<T>(callable);
1142		}
1143
1144		// Serialization support
#	Line 1082 | Line 1146 | public abstract class ForkJoinTask<V> im
1146		private static final long serialVersionUID = -7721805057305804111L;
1147
1148		/**
1149	<	* Save the state to a stream.
1149	>	* Saves the state to a stream (that is, serializes it).
1150		*
1151		* @serialData the current run status and the exception thrown
1152	<	* during execution, or null if none
1152	>	* during execution, or {@code null} if none
1153		* @param s the stream
1154		*/
1155		private void writeObject(java.io.ObjectOutputStream s)
#	Line 1095 | Line 1159 | public abstract class ForkJoinTask<V> im
1159		}
1160
1161		/**
1162	<	* Reconstitute the instance from a stream.
1162	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1163		*
1164		* @param s the stream
1165		*/
1166		private void readObject(java.io.ObjectInputStream s)
1167		throws java.io.IOException, ClassNotFoundException {
1168		s.defaultReadObject();
1105	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1106	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1169		Object ex = s.readObject();
1170		if (ex != null)
1171	<	setDoneExceptionally((Throwable) ex);
1171	>	setExceptionalCompletion((Throwable) ex);
1172	>	}
1173	>
1174	>	// Unsafe mechanics
1175	>
1176	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1177	>	private static final long statusOffset =
1178	>	objectFieldOffset("status", ForkJoinTask.class);
1179	>
1180	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1181	>	try {
1182	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1183	>	} catch (NoSuchFieldException e) {
1184	>	// Convert Exception to corresponding Error
1185	>	NoSuchFieldError error = new NoSuchFieldError(field);
1186	>	error.initCause(e);
1187	>	throw error;
1188	>	}
1189		}
1190
1191	<	// Unsafe mechanics for jsr166y 3rd party package.
1191	>	/**
1192	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1193	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1194	>	* into a jdk.
1195	>	*
1196	>	* @return a sun.misc.Unsafe
1197	>	*/
1198		private static sun.misc.Unsafe getUnsafe() {
1199		try {
1200		return sun.misc.Unsafe.getUnsafe();
1201		} catch (SecurityException se) {
1202		try {
1203		return java.security.AccessController.doPrivileged
1204	<	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1204	>	(new java.security
1205	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1206		public sun.misc.Unsafe run() throws Exception {
1207	<	return getUnsafeByReflection();
1207	>	java.lang.reflect.Field f = sun.misc
1208	>	.Unsafe.class.getDeclaredField("theUnsafe");
1209	>	f.setAccessible(true);
1210	>	return (sun.misc.Unsafe) f.get(null);
1211		}});
1212		} catch (java.security.PrivilegedActionException e) {
1213		throw new RuntimeException("Could not initialize intrinsics",
#	Line 1126 | Line 1215 | public abstract class ForkJoinTask<V> im
1215		}
1216		}
1217		}
1129	–
1130	–	private static sun.misc.Unsafe getUnsafeByReflection()
1131	–	throws NoSuchFieldException, IllegalAccessException {
1132	–	java.lang.reflect.Field f =
1133	–	sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
1134	–	f.setAccessible(true);
1135	–	return (sun.misc.Unsafe) f.get(null);
1136	–	}
1137	–
1138	–	private static long fieldOffset(String fieldName, Class<?> klazz) {
1139	–	try {
1140	–	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName));
1141	–	} catch (NoSuchFieldException e) {
1142	–	// Convert Exception to Error
1143	–	NoSuchFieldError error = new NoSuchFieldError(fieldName);
1144	–	error.initCause(e);
1145	–	throw error;
1146	–	}
1147	–	}
1148	–
1149	–	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1150	–	static final long statusOffset =
1151	–	fieldOffset("status", ForkJoinTask.class);
1152	–
1218		}

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