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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.1 by dl, Tue Jan 6 14:30:31 2009 UTC vs.
Revision 1.67 by dl, Sun Nov 21 14:43:27 2010 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	+
9		import java.io.Serializable;
10	<	import java.util.*;
11	<	import java.util.concurrent.*;
12	<	import java.util.concurrent.atomic.*;
13	<	import sun.misc.Unsafe;
14	<	import java.lang.reflect.*;
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 ForkJoinPool.  A
29	<	* ForkJoinTask is a thread-like entity that is much lighter weight
30	<	* than a normal thread.  Huge numbers of tasks and subtasks may be
31	<	* hosted by a small number of actual threads in a ForkJoinPool,
32	<	* at the price of some usage limitations.
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" {@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 {@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 #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> ForkJoinTasks are forms of <tt>Futures</tt> supporting a
86	<	* limited range of use.  The "lightness" of ForkJoinTasks is due to a
87	<	* set of restrictions (that are only partially statically
88	<	* enforceable) reflecting their intended use as computational tasks
89	<	* calculating pure functions or operating on purely isolated objects.
90	<	* The primary coordination mechanisms supported for ForkJoinTasks are
91	<	* <tt>fork</tt>, that arranges asynchronous execution, and
92	<	* <tt>join</tt>, that doesn't proceed until the task's result has
93	<	* been computed. (Cancellation is also supported).  The computation
94	<	* defined in the <tt>compute</tt> method should avoid
95	<	* <tt>synchronized</tt> methods or blocks, and should minimize
33	<	* blocking synchronization apart from joining other tasks or using
34	<	* synchronizers such as Phasers that are advertised to cooperate with
35	<	* fork/join scheduling. Tasks should also not perform blocking IO,
36	<	* and should ideally access variables that are completely independent
37	<	* of those accessed by other running tasks. Minor breaches of these
38	<	* restrictions, for example using shared output streams, may be
39	<	* tolerable in practice, but frequent use may result in poor
40	<	* performance, and the potential to indefinitely stall if the number
41	<	* of threads not waiting for external synchronization becomes
42	<	* exhausted. This usage restriction is in part enforced by not
43	<	* permitting checked exceptions such as IOExceptions to be
44	<	* thrown. However, computations may still encounter unchecked
45	<	* exceptions, that are rethrown to callers attempting join
46	<	* them. These exceptions may additionally include
47	<	* RejectedExecutionExceptions stemming from internal resource
48	<	* exhaustion such as failure to allocate internal task queues.
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 <tt>ForkJoinTask</tt> class is not usually directly
98	<	* subclassed.  Instead, you subclass one of the abstract classes that
99	<	* support different styles of fork/join processing.  Normally, a
100	<	* concrete ForkJoinTask subclass declares fields comprising its
101	<	* parameters, established in a constructor, and then defines a
102	<	* <tt>compute</tt> method that somehow uses the control methods
103	<	* supplied by this base class. While these methods have
104	<	* <tt>public</tt> access, some of them may only be called from within
105	<	* other ForkJoinTasks. Attempts to invoke them in other contexts
106	<	* result in exceptions or errors including ClassCastException.  The
107	<	* only way to invoke a "main" driver task is to submit it to a
108	<	* ForkJoinPool. Once started, this will usually in turn start other
109	<	* subtasks.
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, 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 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	>	* {@code ClassCastException}.
112		*
113	<	* <p>Most base support methods are <tt>final</tt> because their
114	<	* implementations are intrinsically tied to the underlying
115	<	* lightweight task scheduling framework, and so cannot be overridden.
116	<	* Developers creating new basic styles of fork/join processing should
117	<	* minimally implement protected methods <tt>exec</tt>,
118	<	* <tt>setRawResult</tt>, and <tt>getRawResult</tt>, while also
119	<	* introducing an abstract computational method that can be
120	<	* implemented in its subclasses. To support such extensions,
121	<	* instances of ForkJoinTasks maintain an atomically updated
73	<	* <tt>short</tt> representing user-defined control state.  Control
74	<	* state is guaranteed initially to be zero, and to be negative upon
75	<	* completion, but may otherwise be used for any other control
76	<	* purposes, such as maintaining join counts.  The {@link
77	<	* ForkJoinWorkerThread} class supports additional inspection and
78	<	* tuning methods that can be useful when developing extensions.
113	>	* <p>Most base support methods are {@code final}, to prevent
114	>	* overriding of implementations that are intrinsically tied to the
115	>	* underlying lightweight task scheduling framework.  Developers
116	>	* creating new basic styles of fork/join processing should minimally
117	>	* implement {@code protected} methods {@link #exec}, {@link
118	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
119	>	* an abstract computational method that can be implemented in its
120	>	* subclasses, possibly relying on other {@code protected} methods
121	>	* provided by this class.
122		*
123		* <p>ForkJoinTasks should perform relatively small amounts of
124	<	* computations, othewise splitting into smaller tasks. As a very
125	<	* rough rule of thumb, a task should perform more than 100 and less
126	<	* than 10000 basic computational steps. If tasks are too big, then
127	<	* parellelism cannot improve throughput. If too small, then memory
128	<	* and internal task maintenance overhead may overwhelm processing.
124	>	* computation. Large tasks should be split into smaller subtasks,
125	>	* usually via recursive decomposition. As a very rough rule of thumb,
126	>	* a task should perform more than 100 and less than 10000 basic
127	>	* computational steps. If tasks are too big, then parallelism cannot
128	>	* improve throughput. If too small, then memory and internal task
129	>	* maintenance overhead may overwhelm processing.
130		*
131	<	* <p>ForkJoinTasks are <tt>Serializable</tt>, which enables them to
132	<	* be used in extensions such as remote execution frameworks. However,
133	<	* it is in general safe to serialize tasks only before or after, but
134	<	* not during execution. Serialization is not relied on during
135	<	* execution itself.
131	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
132	>	* and {@link Callable}, that may be of use when mixing execution of
133	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
134	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
135	>	*
136	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
137	>	* used in extensions such as remote execution frameworks. It is
138	>	* sensible to serialize tasks only before or after, but not during,
139	>	* execution. Serialization is not relied on during execution itself.
140	>	*
141	>	* @since 1.7
142	>	* @author Doug Lea
143		*/
144		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
145	<	/**
146	<	* Status field holding all run status. We pack this into a single
147	<	* int both to minimize footprint overhead and to ensure atomicity
148	<	* (updates are via CAS).
149	<	*
150	<	* Status is initially zero, and takes on nonnegative values until
151	<	* completed, upon which status holds COMPLETED. CANCELLED, or
152	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
153	<	* blocking waits by other threads have SIGNAL_MASK bits set --
154	<	* bit 15 for external (nonFJ) waits, and the rest a count of
155	<	* waiting FJ threads.  (This representation relies on
156	<	* ForkJoinPool max thread limits). Completion of a stolen task
157	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
158	<	* though suboptimal for some purposes, we use basic builtin
159	<	* wait/notify to take advantage of "monitor inflation" in JVMs
160	<	* that we would otherwise need to emulate to avoid adding further
161	<	* per-task bookkeeping overhead. Note that bits 16-28 are
162	<	* currently unused. Also value 0x80000000 is available as spare
163	<	* completion value.
164	<	*/
165	<	volatile int status; // accessed directy by pool and workers
166	<
167	<	static final int COMPLETION_MASK      = 0xe0000000;
168	<	static final int NORMAL               = 0xe0000000; // == mask
169	<	static final int CANCELLED            = 0xc0000000;
170	<	static final int EXCEPTIONAL          = 0xa0000000;
171	<	static final int SIGNAL_MASK          = 0x0000ffff;
172	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
173	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
145	>
146	>	/*
147	>	* See the internal documentation of class ForkJoinPool for a
148	>	* general implementation overview.  ForkJoinTasks are mainly
149	>	* responsible for maintaining their "status" field amidst relays
150	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
151	>	* methods of this class are more-or-less layered into (1) basic
152	>	* status maintenance (2) execution and awaiting completion (3)
153	>	* user-level methods that additionally report results. This is
154	>	* sometimes hard to see because this file orders exported methods
155	>	* in a way that flows well in javadocs. In particular, most
156	>	* join mechanics are in method quietlyJoin, below.
157	>	*/
158	>
159	>	/*
160	>	* The status field holds run control status bits packed into a
161	>	* single int to minimize footprint and to ensure atomicity (via
162	>	* CAS).  Status is initially zero, and takes on nonnegative
163	>	* values until completed, upon which status holds value
164	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
165	>	* waits by other threads have the SIGNAL bit set.  Completion of
166	>	* a stolen task with SIGNAL set awakens any waiters via
167	>	* notifyAll. Even though suboptimal for some purposes, we use
168	>	* basic builtin wait/notify to take advantage of "monitor
169	>	* inflation" in JVMs that we would otherwise need to emulate to
170	>	* avoid adding further per-task bookkeeping overhead.  We want
171	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
172	>	* techniques, so use some odd coding idioms that tend to avoid
173	>	* them.
174	>	*/
175	>
176	>	/** The run status of this task */
177	>	volatile int status; // accessed directly by pool and workers
178	>
179	>	private static final int NORMAL      = -1;
180	>	private static final int CANCELLED   = -2;
181	>	private static final int EXCEPTIONAL = -3;
182	>	private static final int SIGNAL      =  1;
183
184		/**
185		* Table of exceptions thrown by tasks, to enable reporting by
186		* callers. Because exceptions are rare, we don't directly keep
187	<	* them with task objects, but instead us a weak ref table.  Note
187	>	* them with task objects, but instead use a weak ref table.  Note
188		* that cancellation exceptions don't appear in the table, but are
189		* instead recorded as status values.
190	<	* Todo: Use ConcurrentReferenceHashMap
190	>	* TODO: Use ConcurrentReferenceHashMap
191		*/
192		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
193		Collections.synchronizedMap
194		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
195
196	<	// within-package utilities
196	>	// Maintaining completion status
197
198		/**
199	<	* Get current worker thread, or null if not a worker thread
199	>	* Marks completion and wakes up threads waiting to join this task,
200	>	* also clearing signal request bits.
201	>	*
202	>	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
203		*/
204	<	static ForkJoinWorkerThread getWorker() {
205	<	Thread t = Thread.currentThread();
206	<	return ((t instanceof ForkJoinWorkerThread)?
207	<	(ForkJoinWorkerThread)t : null);
204	>	private void setCompletion(int completion) {
205	>	int s;
206	>	while ((s = status) >= 0) {
207	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
208	>	if (s != 0)
209	>	synchronized (this) { notifyAll(); }
210	>	break;
211	>	}
212	>	}
213		}
214
215		/**
216	<	* Get pool of current worker thread, or null if not a worker thread
216	>	* Records exception and sets exceptional completion.
217	>	*
218	>	* @return status on exit
219		*/
220	<	static ForkJoinPool getWorkerPool() {
221	<	Thread t = Thread.currentThread();
222	<	return ((t instanceof ForkJoinWorkerThread)?
153	<	((ForkJoinWorkerThread)t).pool : null);
154	<	}
155	<
156	<	final boolean casStatus(int cmp, int val) {
157	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
220	>	private void setExceptionalCompletion(Throwable rex) {
221	>	exceptionMap.put(this, rex);
222	>	setCompletion(EXCEPTIONAL);
223		}
224
225		/**
226	<	* Workaround for not being able to rethrow unchecked exceptions.
226	>	* Blocks a worker thread until completion. Called only by
227	>	* pool. Currently unused -- pool-based waits use timeout
228	>	* version below.
229		*/
230	<	static void rethrowException(Throwable ex) {
231	<	if (ex != null)
232	<	_unsafe.throwException(ex);
230	>	final void internalAwaitDone() {
231	>	int s;         // the odd construction reduces lock bias effects
232	>	while ((s = status) >= 0) {
233	>	try {
234	>	synchronized (this) {
235	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
236	>	wait();
237	>	}
238	>	} catch (InterruptedException ie) {
239	>	cancelIfTerminating();
240	>	}
241	>	}
242		}
243
168	–	// Setting completion status
169	–
244		/**
245	<	* Mark completion and wake up threads waiting to join this task.
246	<	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
245	>	* Blocks a worker thread until completed or timed out.  Called
246	>	* only by pool.
247	>	*
248	>	* @return status on exit
249		*/
250	<	final void setCompletion(int completion) {
251	<	ForkJoinPool pool = getWorkerPool();
252	<	if (pool != null) {
253	<	int s; // Clear signal bits while setting completion status
254	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
255	<
256	<	if ((s & SIGNAL_MASK) != 0) {
257	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
258	<	pool.updateRunningCount(s);
259	<	synchronized(this) { notifyAll(); }
250	>	final int internalAwaitDone(long millis, int nanos) {
251	>	int s;
252	>	if ((s = status) >= 0) {
253	>	try {
254	>	synchronized (this) {
255	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
256	>	wait(millis, nanos);
257	>	}
258	>	} catch (InterruptedException ie) {
259	>	cancelIfTerminating();
260		}
261	+	s = status;
262		}
263	<	else
187	<	externallySetCompletion(completion);
263	>	return s;
264		}
265
266		/**
267	<	* Version of setCompletion for non-FJ threads.  Leaves signal
192	<	* bits for unblocked threads to adjust, and always notifies.
267	>	* Blocks a non-worker-thread until completion.
268		*/
269	<	private void externallySetCompletion(int completion) {
269	>	private void externalAwaitDone() {
270		int s;
271	<	do;while ((s = status) >= 0 &&
272	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
273	<	synchronized(this) { notifyAll(); }
271	>	while ((s = status) >= 0) {
272	>	synchronized (this) {
273	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
274	>	boolean interrupted = false;
275	>	while (status >= 0) {
276	>	try {
277	>	wait();
278	>	} catch (InterruptedException ie) {
279	>	interrupted = true;
280	>	}
281	>	}
282	>	if (interrupted)
283	>	Thread.currentThread().interrupt();
284	>	break;
285	>	}
286	>	}
287	>	}
288		}
289
290		/**
291	<	* Sets status to indicate normal completion
291	>	* Unless done, calls exec and records status if completed, but
292	>	* doesn't wait for completion otherwise. Primary execution method
293	>	* for ForkJoinWorkerThread.
294		*/
295	<	final void setNormalCompletion() {
296	<	// Try typical fast case -- single CAS, no signal, not already done.
297	<	// Manually expand casStatus to improve chances of inlining it
298	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
299	<	setCompletion(NORMAL);
295	>	final void quietlyExec() {
296	>	try {
297	>	if (status < 0 || !exec())
298	>	return;
299	>	} catch (Throwable rex) {
300	>	setExceptionalCompletion(rex);
301	>	return;
302	>	}
303	>	setCompletion(NORMAL); // must be outside try block
304		}
305
306	<	// internal waiting and notification
306	>	// public methods
307
308		/**
309	<	* Performs the actual monitor wait for awaitDone
309	>	* Arranges to asynchronously execute this task.  While it is not
310	>	* necessarily enforced, it is a usage error to fork a task more
311	>	* than once unless it has completed and been reinitialized.
312	>	* Subsequent modifications to the state of this task or any data
313	>	* it operates on are not necessarily consistently observable by
314	>	* any thread other than the one executing it unless preceded by a
315	>	* call to {@link #join} or related methods, or a call to {@link
316	>	* #isDone} returning {@code true}.
317	>	*
318	>	* <p>This method may be invoked only from within {@code
319	>	* ForkJoinTask} computations (as may be determined using method
320	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
321	>	* result in exceptions or errors, possibly including {@code
322	>	* ClassCastException}.
323	>	*
324	>	* @return {@code this}, to simplify usage
325		*/
326	<	private void doAwaitDone() {
327	<	// Minimize lock bias and in/de-flation effects by maximizing
328	<	// chances of waiting inside sync
329	<	try {
220	<	while (status >= 0)
221	<	synchronized(this) { if (status >= 0) wait(); }
222	<	} catch (InterruptedException ie) {
223	<	onInterruptedWait();
224	<	}
326	>	public final ForkJoinTask<V> fork() {
327	>	((ForkJoinWorkerThread) Thread.currentThread())
328	>	.pushTask(this);
329	>	return this;
330		}
331
332		/**
333	<	* Performs the actual monitor wait for awaitDone
333	>	* Returns the result of the computation when it {@link #isDone is done}.
334	>	* This method differs from {@link #get()} in that
335	>	* abnormal completion results in {@code RuntimeException} or
336	>	* {@code Error}, not {@code ExecutionException}.
337	>	*
338	>	* @return the computed result
339		*/
340	<	private void doAwaitDone(long startTime, long nanos) {
341	<	synchronized(this) {
342	<	try {
343	<	while (status >= 0) {
344	<	long nt = nanos - System.nanoTime() - startTime;
345	<	if (nt <= 0)
236	<	break;
237	<	wait(nt / 1000000, (int)(nt % 1000000));
238	<	}
239	<	} catch (InterruptedException ie) {
240	<	onInterruptedWait();
241	<	}
242	<	}
340	>	public final V join() {
341	>	quietlyJoin();
342	>	Throwable ex;
343	>	if (status < NORMAL && (ex = getException()) != null)
344	>	UNSAFE.throwException(ex);
345	>	return getRawResult();
346		}
347
348	<	// Awaiting completion
348	>	/**
349	>	* Commences performing this task, awaits its completion if
350	>	* necessary, and returns its result, or throws an (unchecked)
351	>	* {@code RuntimeException} or {@code Error} if the underlying
352	>	* computation did so.
353	>	*
354	>	* @return the computed result
355	>	*/
356	>	public final V invoke() {
357	>	quietlyInvoke();
358	>	Throwable ex;
359	>	if (status < NORMAL && (ex = getException()) != null)
360	>	UNSAFE.throwException(ex);
361	>	return getRawResult();
362	>	}
363
364		/**
365	<	* Sets status to indicate there is joiner, then waits for join,
366	<	* surrounded with pool notifications.
367	<	* @return status upon exit
365	>	* Forks the given tasks, returning when {@code isDone} holds for
366	>	* each task or an (unchecked) exception is encountered, in which
367	>	* case the exception is rethrown. If more than one task
368	>	* encounters an exception, then this method throws any one of
369	>	* these exceptions. If any task encounters an exception, the
370	>	* other may be cancelled. However, the execution status of
371	>	* individual tasks is not guaranteed upon exceptional return. The
372	>	* status of each task may be obtained using {@link
373	>	* #getException()} and related methods to check if they have been
374	>	* cancelled, completed normally or exceptionally, or left
375	>	* unprocessed.
376	>	*
377	>	* <p>This method may be invoked only from within {@code
378	>	* ForkJoinTask} computations (as may be determined using method
379	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
380	>	* result in exceptions or errors, possibly including {@code
381	>	* ClassCastException}.
382	>	*
383	>	* @param t1 the first task
384	>	* @param t2 the second task
385	>	* @throws NullPointerException if any task is null
386		*/
387	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
388	<	ForkJoinPool pool = w == null? null : w.pool;
389	<	int s;
390	<	while ((s = status) >= 0) {
391	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
392	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
393	<	doAwaitDone();
394	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
395	<	adjustPoolCountsOnUnblock(pool);
396	<	break;
387	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
388	>	t2.fork();
389	>	t1.invoke();
390	>	t2.join();
391	>	}
392	>
393	>	/**
394	>	* Forks the given tasks, returning when {@code isDone} holds for
395	>	* each task or an (unchecked) exception is encountered, in which
396	>	* case the exception is rethrown. If more than one task
397	>	* encounters an exception, then this method throws any one of
398	>	* these exceptions. If any task encounters an exception, others
399	>	* may be cancelled. However, the execution status of individual
400	>	* tasks is not guaranteed upon exceptional return. The status of
401	>	* each task may be obtained using {@link #getException()} and
402	>	* related methods to check if they have been cancelled, completed
403	>	* normally or exceptionally, or left unprocessed.
404	>	*
405	>	* <p>This method may be invoked only from within {@code
406	>	* ForkJoinTask} computations (as may be determined using method
407	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
408	>	* result in exceptions or errors, possibly including {@code
409	>	* ClassCastException}.
410	>	*
411	>	* @param tasks the tasks
412	>	* @throws NullPointerException if any task is null
413	>	*/
414	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
415	>	Throwable ex = null;
416	>	int last = tasks.length - 1;
417	>	for (int i = last; i >= 0; --i) {
418	>	ForkJoinTask<?> t = tasks[i];
419	>	if (t == null) {
420	>	if (ex == null)
421	>	ex = new NullPointerException();
422	>	}
423	>	else if (i != 0)
424	>	t.fork();
425	>	else {
426	>	t.quietlyInvoke();
427	>	if (ex == null && t.status < NORMAL)
428	>	ex = t.getException();
429		}
430		}
431	<	return s;
431	>	for (int i = 1; i <= last; ++i) {
432	>	ForkJoinTask<?> t = tasks[i];
433	>	if (t != null) {
434	>	if (ex != null)
435	>	t.cancel(false);
436	>	else {
437	>	t.quietlyJoin();
438	>	if (ex == null && t.status < NORMAL)
439	>	ex = t.getException();
440	>	}
441	>	}
442	>	}
443	>	if (ex != null)
444	>	UNSAFE.throwException(ex);
445		}
446
447		/**
448	<	* Timed version of awaitDone
449	<	* @return status upon exit
448	>	* Forks all tasks in the specified collection, returning when
449	>	* {@code isDone} holds for each task or an (unchecked) exception
450	>	* is encountered, in which case the exception is rethrown. If
451	>	* more than one task encounters an exception, then this method
452	>	* throws any one of these exceptions. If any task encounters an
453	>	* exception, others may be cancelled. However, the execution
454	>	* status of individual tasks is not guaranteed upon exceptional
455	>	* return. The status of each task may be obtained using {@link
456	>	* #getException()} and related methods to check if they have been
457	>	* cancelled, completed normally or exceptionally, or left
458	>	* unprocessed.
459	>	*
460	>	* <p>This method may be invoked only from within {@code
461	>	* ForkJoinTask} computations (as may be determined using method
462	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
463	>	* result in exceptions or errors, possibly including {@code
464	>	* ClassCastException}.
465	>	*
466	>	* @param tasks the collection of tasks
467	>	* @return the tasks argument, to simplify usage
468	>	* @throws NullPointerException if tasks or any element are null
469		*/
470	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
471	<	ForkJoinPool pool = w == null? null : w.pool;
472	<	int s;
473	<	while ((s = status) >= 0) {
474	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
475	<	long startTime = System.nanoTime();
476	<	if (pool == null || !pool.preJoin(this, false))
477	<	doAwaitDone(startTime, nanos);
478	<	if ((s = status) >= 0) {
479	<	adjustPoolCountsOnCancelledWait(pool);
480	<	s = status;
470	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
471	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
472	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
473	>	return tasks;
474	>	}
475	>	@SuppressWarnings("unchecked")
476	>	List<? extends ForkJoinTask<?>> ts =
477	>	(List<? extends ForkJoinTask<?>>) tasks;
478	>	Throwable ex = null;
479	>	int last = ts.size() - 1;
480	>	for (int i = last; i >= 0; --i) {
481	>	ForkJoinTask<?> t = ts.get(i);
482	>	if (t == null) {
483	>	if (ex == null)
484	>	ex = new NullPointerException();
485	>	}
486	>	else if (i != 0)
487	>	t.fork();
488	>	else {
489	>	t.quietlyInvoke();
490	>	if (ex == null && t.status < NORMAL)
491	>	ex = t.getException();
492	>	}
493	>	}
494	>	for (int i = 1; i <= last; ++i) {
495	>	ForkJoinTask<?> t = ts.get(i);
496	>	if (t != null) {
497	>	if (ex != null)
498	>	t.cancel(false);
499	>	else {
500	>	t.quietlyJoin();
501	>	if (ex == null && t.status < NORMAL)
502	>	ex = t.getException();
503		}
283	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
284	–	adjustPoolCountsOnUnblock(pool);
285	–	break;
504		}
505		}
506	<	return s;
506	>	if (ex != null)
507	>	UNSAFE.throwException(ex);
508	>	return tasks;
509		}
510
511		/**
512	<	* Notify pool that thread is unblocked. Called by signalled
513	<	* threads when woken by non-FJ threads (which is atypical).
512	>	* Attempts to cancel execution of this task. This attempt will
513	>	* fail if the task has already completed, has already been
514	>	* cancelled, or could not be cancelled for some other reason. If
515	>	* successful, and this task has not started when cancel is
516	>	* called, execution of this task is suppressed, {@link
517	>	* #isCancelled} will report true, and {@link #join} will result
518	>	* in a {@code CancellationException} being thrown.
519	>	*
520	>	* <p>This method may be overridden in subclasses, but if so, must
521	>	* still ensure that these minimal properties hold. In particular,
522	>	* the {@code cancel} method itself must not throw exceptions.
523	>	*
524	>	* <p>This method is designed to be invoked by <em>other</em>
525	>	* tasks. To terminate the current task, you can just return or
526	>	* throw an unchecked exception from its computation method, or
527	>	* invoke {@link #completeExceptionally}.
528	>	*
529	>	* @param mayInterruptIfRunning this value is ignored in the
530	>	* default implementation because tasks are not
531	>	* cancelled via interruption
532	>	*
533	>	* @return {@code true} if this task is now cancelled
534		*/
535	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
536	<	int s;
537	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
298	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
299	<	pool.updateRunningCount(s);
535	>	public boolean cancel(boolean mayInterruptIfRunning) {
536	>	setCompletion(CANCELLED);
537	>	return status == CANCELLED;
538		}
539
540		/**
541	<	* Notify pool to adjust counts on cancelled or timed out wait
541	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
542	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
543	>	* exceptions, but if it does anyway, we have no recourse during
544	>	* shutdown, so guard against this case.
545		*/
546	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
547	<	if (pool != null) {
548	<	int s;
549	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
309	<	if (casStatus(s, s - 1)) {
310	<	pool.updateRunningCount(1);
311	<	break;
312	<	}
313	<	}
546	>	final void cancelIgnoringExceptions() {
547	>	try {
548	>	cancel(false);
549	>	} catch (Throwable ignore) {
550		}
551		}
552
553	<	private void onInterruptedWait() {
553	>	/**
554	>	* Cancels if current thread is a terminating worker thread,
555	>	* ignoring any exceptions thrown by cancel.
556	>	*/
557	>	final void cancelIfTerminating() {
558		Thread t = Thread.currentThread();
559	<	if (t instanceof ForkJoinWorkerThread) {
560	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)t;
321	<	if (w.isTerminating())
322	<	cancelIgnoreExceptions();
323	<	}
324	<	else { // re-interrupt
559	>	if ((t instanceof ForkJoinWorkerThread) &&
560	>	((ForkJoinWorkerThread) t).isTerminating()) {
561		try {
562	<	t.interrupt();
563	<	} catch (SecurityException ignore) {
562	>	cancel(false);
563	>	} catch (Throwable ignore) {
564		}
565		}
566		}
567
568	<	// Recording and reporting exceptions
568	>	public final boolean isDone() {
569	>	return status < 0;
570	>	}
571
572	<	private void setDoneExceptionally(Throwable rex) {
573	<	exceptionMap.put(this, rex);
336	<	setCompletion(EXCEPTIONAL);
572	>	public final boolean isCancelled() {
573	>	return status == CANCELLED;
574		}
575
576		/**
577	<	* Throws the exception associated with status s;
578	<	* @throws the exception
577	>	* Returns {@code true} if this task threw an exception or was cancelled.
578	>	*
579	>	* @return {@code true} if this task threw an exception or was cancelled
580		*/
581	<	private void reportException(int s) {
582	<	if ((s &= COMPLETION_MASK) < NORMAL) {
345	<	if (s == CANCELLED)
346	<	throw new CancellationException();
347	<	else
348	<	rethrowException(exceptionMap.get(this));
349	<	}
581	>	public final boolean isCompletedAbnormally() {
582	>	return status < NORMAL;
583		}
584
585		/**
586	<	* Returns result or throws exception using j.u.c.Future conventions
587	<	* Only call when isDone known to be true.
586	>	* Returns {@code true} if this task completed without throwing an
587	>	* exception and was not cancelled.
588	>	*
589	>	* @return {@code true} if this task completed without throwing an
590	>	* exception and was not cancelled
591		*/
592	<	private V reportFutureResult()
593	<	throws ExecutionException, InterruptedException {
358	<	int s = status & COMPLETION_MASK;
359	<	if (s < NORMAL) {
360	<	Throwable ex;
361	<	if (s == CANCELLED)
362	<	throw new CancellationException();
363	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
364	<	throw new ExecutionException(ex);
365	<	if (Thread.interrupted())
366	<	throw new InterruptedException();
367	<	}
368	<	return getRawResult();
592	>	public final boolean isCompletedNormally() {
593	>	return status == NORMAL;
594		}
595
596		/**
597	<	* Returns result or throws exception using j.u.c.Future conventions
598	<	* with timeouts
597	>	* Returns the exception thrown by the base computation, or a
598	>	* {@code CancellationException} if cancelled, or {@code null} if
599	>	* none or if the method has not yet completed.
600	>	*
601	>	* @return the exception, or {@code null} if none
602		*/
603	<	private V reportTimedFutureResult()
604	<	throws InterruptedException, ExecutionException, TimeoutException {
605	<	Throwable ex;
606	<	int s = status & COMPLETION_MASK;
607	<	if (s == NORMAL)
380	<	return getRawResult();
381	<	if (s == CANCELLED)
382	<	throw new CancellationException();
383	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
384	<	throw new ExecutionException(ex);
385	<	if (Thread.interrupted())
386	<	throw new InterruptedException();
387	<	throw new TimeoutException();
388	<	}
389	<
390	<	// internal execution methods
391	<
392	<	/**
393	<	* Calls exec, recording completion, and rethrowing exception if
394	<	* encountered. Caller should normally check status before calling
395	<	* @return true if completed normally
396	<	*/
397	<	private boolean tryExec() {
398	<	try { // try block must contain only call to exec
399	<	if (!exec())
400	<	return false;
401	<	} catch (Throwable rex) {
402	<	setDoneExceptionally(rex);
403	<	rethrowException(rex);
404	<	return false; // not reached
405	<	}
406	<	setNormalCompletion();
407	<	return true;
603	>	public final Throwable getException() {
604	>	int s = status;
605	>	return ((s >= NORMAL)    ? null :
606	>	(s == CANCELLED) ? new CancellationException() :
607	>	exceptionMap.get(this));
608		}
609
610		/**
611	<	* Main execution method used by worker threads. Invokes
612	<	* base computation unless already complete
611	>	* Completes this task abnormally, and if not already aborted or
612	>	* cancelled, causes it to throw the given exception upon
613	>	* {@code join} and related operations. This method may be used
614	>	* to induce exceptions in asynchronous tasks, or to force
615	>	* completion of tasks that would not otherwise complete.  Its use
616	>	* in other situations is discouraged.  This method is
617	>	* overridable, but overridden versions must invoke {@code super}
618	>	* implementation to maintain guarantees.
619	>	*
620	>	* @param ex the exception to throw. If this exception is not a
621	>	* {@code RuntimeException} or {@code Error}, the actual exception
622	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
623		*/
624	<	final void quietlyExec() {
625	<	if (status >= 0) {
626	<	try {
627	<	if (!exec())
418	<	return;
419	<	} catch(Throwable rex) {
420	<	setDoneExceptionally(rex);
421	<	return;
422	<	}
423	<	setNormalCompletion();
424	<	}
624	>	public void completeExceptionally(Throwable ex) {
625	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
626	>	(ex instanceof Error) ? ex :
627	>	new RuntimeException(ex));
628		}
629
630		/**
631	<	* Calls exec, recording but not rethrowing exception
632	<	* Caller should normally check status before calling
633	<	* @return true if completed normally
631	>	* Completes this task, and if not already aborted or cancelled,
632	>	* returning the given value as the result of subsequent
633	>	* invocations of {@code join} and related operations. This method
634	>	* may be used to provide results for asynchronous tasks, or to
635	>	* provide alternative handling for tasks that would not otherwise
636	>	* complete normally. Its use in other situations is
637	>	* discouraged. This method is overridable, but overridden
638	>	* versions must invoke {@code super} implementation to maintain
639	>	* guarantees.
640	>	*
641	>	* @param value the result value for this task
642		*/
643	<	private boolean tryQuietlyInvoke() {
643	>	public void complete(V value) {
644		try {
645	<	if (!exec())
435	<	return false;
645	>	setRawResult(value);
646		} catch (Throwable rex) {
647	<	setDoneExceptionally(rex);
648	<	return false;
647	>	setExceptionalCompletion(rex);
648	>	return;
649		}
650	<	setNormalCompletion();
441	<	return true;
650	>	setCompletion(NORMAL);
651		}
652
653		/**
654	<	* Cancel, ignoring any exceptions it throws
654	>	* Waits if necessary for the computation to complete, and then
655	>	* retrieves its result.
656	>	*
657	>	* @return the computed result
658	>	* @throws CancellationException if the computation was cancelled
659	>	* @throws ExecutionException if the computation threw an
660	>	* exception
661	>	* @throws InterruptedException if the current thread is not a
662	>	* member of a ForkJoinPool and was interrupted while waiting
663		*/
664	<	final void cancelIgnoreExceptions() {
665	<	try {
666	<	cancel(false);
667	<	} catch(Throwable ignore) {
664	>	public final V get() throws InterruptedException, ExecutionException {
665	>	int s;
666	>	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
667	>	quietlyJoin();
668	>	s = status;
669		}
670	<	}
671	<
672	<	// public methods
673	<
674	<	/**
675	<	* Arranges to asynchronously execute this task.  While it is not
676	<	* necessarily enforced, it is a usage error to fork a task more
677	<	* than once unless it has completed and been reinitialized.  This
678	<	* method may be invoked only from within other ForkJoinTask
679	<	* computations. Attempts to invoke in other contexts result in
680	<	* exceptions or errors including ClassCastException.
681	<	*/
682	<	public final void fork() {
683	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
670	>	else {
671	>	while ((s = status) >= 0) {
672	>	synchronized (this) { // interruptible form of awaitDone
673	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
674	>	s, SIGNAL)) {
675	>	while (status >= 0)
676	>	wait();
677	>	}
678	>	}
679	>	}
680	>	}
681	>	if (s < NORMAL) {
682	>	Throwable ex;
683	>	if (s == CANCELLED)
684	>	throw new CancellationException();
685	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
686	>	throw new ExecutionException(ex);
687	>	}
688	>	return getRawResult();
689		}
690
691		/**
692	<	* Returns the result of the computation when it is ready.
693	<	* This method differs from <tt>get</tt> in that abnormal
471	<	* completion results in RuntimeExceptions or Errors, not
472	<	* ExecutionExceptions.
692	>	* Waits if necessary for at most the given time for the computation
693	>	* to complete, and then retrieves its result, if available.
694		*
695	+	* @param timeout the maximum time to wait
696	+	* @param unit the time unit of the timeout argument
697		* @return the computed result
698	+	* @throws CancellationException if the computation was cancelled
699	+	* @throws ExecutionException if the computation threw an
700	+	* exception
701	+	* @throws InterruptedException if the current thread is not a
702	+	* member of a ForkJoinPool and was interrupted while waiting
703	+	* @throws TimeoutException if the wait timed out
704		*/
476	–	public final V join() {
477	–	ForkJoinWorkerThread w = getWorker();
478	–	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
479	–	reportException(awaitDone(w, true));
480	–	return getRawResult();
481	–	}
482	–
483	–	public final V get() throws InterruptedException, ExecutionException {
484	–	ForkJoinWorkerThread w = getWorker();
485	–	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
486	–	awaitDone(w, true);
487	–	return reportFutureResult();
488	–	}
489	–
705		public final V get(long timeout, TimeUnit unit)
706		throws InterruptedException, ExecutionException, TimeoutException {
707	<	ForkJoinWorkerThread w = getWorker();
708	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
709	<	awaitDone(w, unit.toNanos(timeout));
710	<	return reportTimedFutureResult();
711	<	}
712	<
713	<	/**
714	<	* Possibly executes other tasks until this task is ready, then
715	<	* returns the result of the computation.  This method may be more
716	<	* efficient than <tt>join</tt>, but is only applicable when there
717	<	* are no potemtial dependencies between continuation of the
718	<	* current task and that of any other task that might be executed
719	<	* while helping. (This usually holds for pure divide-and-conquer
720	<	* tasks).
721	<	* @return the computed result
722	<	*/
723	<	public final V helpJoin() {
724	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
725	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
726	<	reportException(w.helpJoinTask(this));
707	>	long nanos = unit.toNanos(timeout);
708	>	if (status >= 0) {
709	>	Thread t = Thread.currentThread();
710	>	if (t instanceof ForkJoinWorkerThread) {
711	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
712	>	boolean completed = false; // timed variant of quietlyJoin
713	>	if (w.unpushTask(this)) {
714	>	try {
715	>	completed = exec();
716	>	} catch (Throwable rex) {
717	>	setExceptionalCompletion(rex);
718	>	}
719	>	}
720	>	if (completed)
721	>	setCompletion(NORMAL);
722	>	else if (status >= 0)
723	>	w.joinTask(this, true, nanos);
724	>	}
725	>	else if (Thread.interrupted())
726	>	throw new InterruptedException();
727	>	else {
728	>	long startTime = System.nanoTime();
729	>	int s; long nt;
730	>	while ((s = status) >= 0 &&
731	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
732	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,
733	>	SIGNAL)) {
734	>	long ms = nt / 1000000;
735	>	int ns = (int) (nt % 1000000);
736	>	synchronized (this) {
737	>	if (status >= 0)
738	>	wait(ms, ns); // exit on IE throw
739	>	}
740	>	}
741	>	}
742	>	}
743	>	}
744	>	int es = status;
745	>	if (es != NORMAL) {
746	>	Throwable ex;
747	>	if (es == CANCELLED)
748	>	throw new CancellationException();
749	>	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
750	>	throw new ExecutionException(ex);
751	>	throw new TimeoutException();
752	>	}
753		return getRawResult();
754		}
755
756		/**
757	<	* Performs this task, awaits its completion if necessary, and
517	<	* return its result.
518	<	* @throws Throwable (a RuntimeException, Error, or unchecked
519	<	* exception) if the underlying computation did so.
520	<	* @return the computed result
521	<	*/
522	<	public final V invoke() {
523	<	if (status >= 0 && tryExec())
524	<	return getRawResult();
525	<	else
526	<	return join();
527	<	}
528	<
529	<	/**
530	<	* Joins this task, without returning its result or throwing an
757	>	* Joins this task, without returning its result or throwing its
758		* exception. This method may be useful when processing
759		* collections of tasks when some have been cancelled or otherwise
760		* known to have aborted.
761		*/
762		public final void quietlyJoin() {
763	<	if (status >= 0) {
764	<	ForkJoinWorkerThread w = getWorker();
765	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
766	<	awaitDone(w, true);
763	>	Thread t;
764	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
765	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
766	>	if (status >= 0) {
767	>	if (w.unpushTask(this)) {
768	>	boolean completed;
769	>	try {
770	>	completed = exec();
771	>	} catch (Throwable rex) {
772	>	setExceptionalCompletion(rex);
773	>	return;
774	>	}
775	>	if (completed) {
776	>	setCompletion(NORMAL);
777	>	return;
778	>	}
779	>	}
780	>	w.joinTask(this, false, 0L);
781	>	}
782		}
783	+	else
784	+	externalAwaitDone();
785		}
786
787		/**
788	<	* Possibly executes other tasks until this task is ready.
788	>	* Commences performing this task and awaits its completion if
789	>	* necessary, without returning its result or throwing its
790	>	* exception.
791		*/
792	<	public final void quietlyHelpJoin() {
792	>	public final void quietlyInvoke() {
793		if (status >= 0) {
794	<	ForkJoinWorkerThread w =
795	<	(ForkJoinWorkerThread)(Thread.currentThread());
796	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
797	<	w.helpJoinTask(this);
794	>	boolean completed;
795	>	try {
796	>	completed = exec();
797	>	} catch (Throwable rex) {
798	>	setExceptionalCompletion(rex);
799	>	return;
800	>	}
801	>	if (completed)
802	>	setCompletion(NORMAL);
803	>	else
804	>	quietlyJoin();
805		}
806		}
807
808		/**
809	<	* Performs this task and awaits its completion if necessary,
810	<	* without returning its result or throwing an exception. This
811	<	* method may be useful when processing collections of tasks when
812	<	* some have been cancelled or otherwise known to have aborted.
809	>	* Possibly executes tasks until the pool hosting the current task
810	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
811	>	* be of use in designs in which many tasks are forked, but none
812	>	* are explicitly joined, instead executing them until all are
813	>	* processed.
814	>	*
815	>	* <p>This method may be invoked only from within {@code
816	>	* ForkJoinTask} computations (as may be determined using method
817	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
818	>	* result in exceptions or errors, possibly including {@code
819	>	* ClassCastException}.
820		*/
821	<	public final void quietlyInvoke() {
822	<	if (status >= 0 && !tryQuietlyInvoke())
823	<	quietlyJoin();
821	>	public static void helpQuiesce() {
822	>	((ForkJoinWorkerThread) Thread.currentThread())
823	>	.helpQuiescePool();
824		}
825
826		/**
827	<	* Returns true if the computation performed by this task has
828	<	* completed (or has been cancelled).
829	<	* @return true if this computation has completed
827	>	* Resets the internal bookkeeping state of this task, allowing a
828	>	* subsequent {@code fork}. This method allows repeated reuse of
829	>	* this task, but only if reuse occurs when this task has either
830	>	* never been forked, or has been forked, then completed and all
831	>	* outstanding joins of this task have also completed. Effects
832	>	* under any other usage conditions are not guaranteed.
833	>	* This method may be useful when executing
834	>	* pre-constructed trees of subtasks in loops.
835	>	*
836	>	* <p>Upon completion of this method, {@code isDone()} reports
837	>	* {@code false}, and {@code getException()} reports {@code
838	>	* null}. However, the value returned by {@code getRawResult} is
839	>	* unaffected. To clear this value, you can invoke {@code
840	>	* setRawResult(null)}.
841		*/
842	<	public final boolean isDone() {
843	<	return status < 0;
842	>	public void reinitialize() {
843	>	if (status == EXCEPTIONAL)
844	>	exceptionMap.remove(this);
845	>	status = 0;
846		}
847
848		/**
849	<	* Returns true if this task was cancelled.
850	<	* @return true if this task was cancelled
849	>	* Returns the pool hosting the current task execution, or null
850	>	* if this task is executing outside of any ForkJoinPool.
851	>	*
852	>	* @see #inForkJoinPool
853	>	* @return the pool, or {@code null} if none
854		*/
855	<	public final boolean isCancelled() {
856	<	return (status & COMPLETION_MASK) == CANCELLED;
855	>	public static ForkJoinPool getPool() {
856	>	Thread t = Thread.currentThread();
857	>	return (t instanceof ForkJoinWorkerThread) ?
858	>	((ForkJoinWorkerThread) t).pool : null;
859		}
860
861		/**
862	<	* Returns true if this task threw an exception or was cancelled
863	<	* @return true if this task threw an exception or was cancelled
862	>	* Returns {@code true} if the current thread is executing as a
863	>	* ForkJoinPool computation.
864	>	*
865	>	* @return {@code true} if the current thread is executing as a
866	>	* ForkJoinPool computation, or false otherwise
867		*/
868	<	public final boolean completedAbnormally() {
869	<	return (status & COMPLETION_MASK) < NORMAL;
868	>	public static boolean inForkJoinPool() {
869	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
870		}
871
872		/**
873	<	* Returns the exception thrown by the base computation, or a
874	<	* CancellationException if cancelled, or null if none or if the
875	<	* method has not yet completed.
876	<	* @return the exception, or null if none
873	>	* Tries to unschedule this task for execution. This method will
874	>	* typically succeed if this task is the most recently forked task
875	>	* by the current thread, and has not commenced executing in
876	>	* another thread.  This method may be useful when arranging
877	>	* alternative local processing of tasks that could have been, but
878	>	* were not, stolen.
879	>	*
880	>	* <p>This method may be invoked only from within {@code
881	>	* ForkJoinTask} computations (as may be determined using method
882	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
883	>	* result in exceptions or errors, possibly including {@code
884	>	* ClassCastException}.
885	>	*
886	>	* @return {@code true} if unforked
887		*/
888	<	public final Throwable getException() {
889	<	int s = status & COMPLETION_MASK;
890	<	if (s >= NORMAL)
600	<	return null;
601	<	if (s == CANCELLED)
602	<	return new CancellationException();
603	<	return exceptionMap.get(this);
888	>	public boolean tryUnfork() {
889	>	return ((ForkJoinWorkerThread) Thread.currentThread())
890	>	.unpushTask(this);
891		}
892
893		/**
894	<	* Asserts that the results of this task's computation will not be
895	<	* used. If a cancellation occurs before this task is processed,
896	<	* then its <tt>compute</tt> method will not be executed,
897	<	* <tt>isCancelled</tt> will report true, and <tt>join</tt> will
611	<	* result in a CancellationException being thrown. Otherwise, when
612	<	* cancellation races with completion, there are no guarantees
613	<	* about whether <tt>isCancelled</tt> will report true, whether
614	<	* <tt>join</tt> will return normally or via an exception, or
615	<	* whether these behaviors will remain consistent upon repeated
616	<	* invocation.
894	>	* Returns an estimate of the number of tasks that have been
895	>	* forked by the current worker thread but not yet executed. This
896	>	* value may be useful for heuristic decisions about whether to
897	>	* fork other tasks.
898		*
899	<	* <p>This method may be overridden in subclasses, but if so, must
900	<	* still ensure that these minimal properties hold. In particular,
901	<	* the cancel method itself must not throw exceptions.
899	>	* <p>This method may be invoked only from within {@code
900	>	* ForkJoinTask} computations (as may be determined using method
901	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
902	>	* result in exceptions or errors, possibly including {@code
903	>	* ClassCastException}.
904		*
905	<	* <p> This method is designed to be invoked by <em>other</em>
906	<	* tasks. To terminate the current task, you can just return or
907	<	* throw an unchecked exception from its computation method, or
908	<	* invoke <tt>completeExceptionally(someException)</tt>.
905	>	* @return the number of tasks
906	>	*/
907	>	public static int getQueuedTaskCount() {
908	>	return ((ForkJoinWorkerThread) Thread.currentThread())
909	>	.getQueueSize();
910	>	}
911	>
912	>	/**
913	>	* Returns an estimate of how many more locally queued tasks are
914	>	* held by the current worker thread than there are other worker
915	>	* threads that might steal them.  This value may be useful for
916	>	* heuristic decisions about whether to fork other tasks. In many
917	>	* usages of ForkJoinTasks, at steady state, each worker should
918	>	* aim to maintain a small constant surplus (for example, 3) of
919	>	* tasks, and to process computations locally if this threshold is
920	>	* exceeded.
921		*
922	<	* @param mayInterruptIfRunning this value is ignored in the
923	<	* default implementation because tasks are not in general
924	<	* cancelled via interruption.
922	>	* <p>This method may be invoked only from within {@code
923	>	* ForkJoinTask} computations (as may be determined using method
924	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
925	>	* result in exceptions or errors, possibly including {@code
926	>	* ClassCastException}.
927		*
928	<	* @return true if this task is now cancelled
928	>	* @return the surplus number of tasks, which may be negative
929		*/
930	<	public boolean cancel(boolean mayInterruptIfRunning) {
931	<	setCompletion(CANCELLED);
932	<	return (status & COMPLETION_MASK) == CANCELLED;
930	>	public static int getSurplusQueuedTaskCount() {
931	>	return ((ForkJoinWorkerThread) Thread.currentThread())
932	>	.getEstimatedSurplusTaskCount();
933		}
934
935	+	// Extension methods
936	+
937		/**
938	<	* Completes this task abnormally, and if not already aborted or
939	<	* cancelled, causes it to throw the given exception upon
940	<	* <tt>join</tt> and related operations. This method may be used
941	<	* to induce exceptions in asynchronous tasks, or to force
942	<	* completion of tasks that would not otherwise complete.  This
943	<	* method is overridable, but overridden versions must invoke
944	<	* <tt>super</tt> implementation to maintain guarantees.
646	<	* @param ex the exception to throw. If this exception is
647	<	* not a RuntimeException or Error, the actual exception thrown
648	<	* will be a RuntimeException with cause ex.
938	>	* Returns the result that would be returned by {@link #join}, even
939	>	* if this task completed abnormally, or {@code null} if this task
940	>	* is not known to have been completed.  This method is designed
941	>	* to aid debugging, as well as to support extensions. Its use in
942	>	* any other context is discouraged.
943	>	*
944	>	* @return the result, or {@code null} if not completed
945		*/
946	<	public void completeExceptionally(Throwable ex) {
651	<	setDoneExceptionally((ex instanceof RuntimeException) ||
652	<	(ex instanceof Error)? ex :
653	<	new RuntimeException(ex));
654	<	}
946	>	public abstract V getRawResult();
947
948		/**
949	<	* Completes this task, and if not already aborted or cancelled,
950	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
951	<	* operations. This method may be used to provide results for
660	<	* asynchronous tasks, or to provide alternative handling for
661	<	* tasks that would not otherwise complete normally.
949	>	* Forces the given value to be returned as a result.  This method
950	>	* is designed to support extensions, and should not in general be
951	>	* called otherwise.
952		*
953	<	* @param value the result value for this task.
953	>	* @param value the value
954		*/
955	<	public void complete(V value) {
666	<	try {
667	<	setRawResult(value);
668	<	} catch(Throwable rex) {
669	<	setDoneExceptionally(rex);
670	<	return;
671	<	}
672	<	setNormalCompletion();
673	<	}
955	>	protected abstract void setRawResult(V value);
956
957		/**
958	<	* Resets the internal bookkeeping state of this task, allowing a
959	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
960	<	* this task, but only if reuse occurs when this task has either
961	<	* never been forked, or has been forked, then completed and all
962	<	* outstanding joins of this task have also completed. Effects
963	<	* under any other usage conditions are not guaranteed, and are
964	<	* almost surely wrong. This method may be useful when executing
965	<	* pre-constructed trees of subtasks in loops.
958	>	* Immediately performs the base action of this task.  This method
959	>	* is designed to support extensions, and should not in general be
960	>	* called otherwise. The return value controls whether this task
961	>	* is considered to be done normally. It may return false in
962	>	* asynchronous actions that require explicit invocations of
963	>	* {@link #complete} to become joinable. It may also throw an
964	>	* (unchecked) exception to indicate abnormal exit.
965	>	*
966	>	* @return {@code true} if completed normally
967		*/
968	<	public void reinitialize() {
686	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
687	<	exceptionMap.remove(this);
688	<	status = 0;
689	<	}
968	>	protected abstract boolean exec();
969
970		/**
971	<	* Tries to unschedule this task for execution. This method will
972	<	* typically succeed if this task is the next task that would be
973	<	* executed by the current thread, and will typically fail (return
974	<	* false) otherwise. This method may be useful when arranging
975	<	* faster local processing of tasks that could have been, but were
976	<	* not, stolen.
977	<	* @return true if unforked
971	>	* Returns, but does not unschedule or execute, a task queued by
972	>	* the current thread but not yet executed, if one is immediately
973	>	* available. There is no guarantee that this task will actually
974	>	* be polled or executed next. Conversely, this method may return
975	>	* null even if a task exists but cannot be accessed without
976	>	* contention with other threads.  This method is designed
977	>	* primarily to support extensions, and is unlikely to be useful
978	>	* otherwise.
979	>	*
980	>	* <p>This method may be invoked only from within {@code
981	>	* ForkJoinTask} computations (as may be determined using method
982	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
983	>	* result in exceptions or errors, possibly including {@code
984	>	* ClassCastException}.
985	>	*
986	>	* @return the next task, or {@code null} if none are available
987		*/
988	<	public boolean tryUnfork() {
989	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
988	>	protected static ForkJoinTask<?> peekNextLocalTask() {
989	>	return ((ForkJoinWorkerThread) Thread.currentThread())
990	>	.peekTask();
991		}
992
993		/**
994	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
995	<	* of them or an exception is encountered. This method may be
996	<	* invoked only from within other ForkJoinTask
997	<	* computations. Attempts to invoke in other contexts result in
998	<	* exceptions or errors including ClassCastException.
999	<	* @param t1 one task
1000	<	* @param t2 the other task
1001	<	* @throws NullPointerException if t1 or t2 are null
1002	<	* @throws RuntimeException or Error if either task did so.
994	>	* Unschedules and returns, without executing, the next task
995	>	* queued by the current thread but not yet executed.  This method
996	>	* is designed primarily to support extensions, and is unlikely to
997	>	* be useful otherwise.
998	>	*
999	>	* <p>This method may be invoked only from within {@code
1000	>	* ForkJoinTask} computations (as may be determined using method
1001	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1002	>	* result in exceptions or errors, possibly including {@code
1003	>	* ClassCastException}.
1004	>	*
1005	>	* @return the next task, or {@code null} if none are available
1006		*/
1007	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
1008	<	t2.fork();
1009	<	t1.invoke();
718	<	t2.join();
1007	>	protected static ForkJoinTask<?> pollNextLocalTask() {
1008	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1009	>	.pollLocalTask();
1010		}
1011
1012		/**
1013	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
1014	<	* all of them. If any task encounters an exception, others may be
1015	<	* cancelled.  This method may be invoked only from within other
1016	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1017	<	* result in exceptions or errors including ClassCastException.
1018	<	* @param tasks the array of tasks
1019	<	* @throws NullPointerException if tasks or any element are null.
1020	<	* @throws RuntimeException or Error if any task did so.
1013	>	* Unschedules and returns, without executing, the next task
1014	>	* queued by the current thread but not yet executed, if one is
1015	>	* available, or if not available, a task that was forked by some
1016	>	* other thread, if available. Availability may be transient, so a
1017	>	* {@code null} result does not necessarily imply quiescence
1018	>	* of the pool this task is operating in.  This method is designed
1019	>	* primarily to support extensions, and is unlikely to be useful
1020	>	* otherwise.
1021	>	*
1022	>	* <p>This method may be invoked only from within {@code
1023	>	* ForkJoinTask} computations (as may be determined using method
1024	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1025	>	* result in exceptions or errors, possibly including {@code
1026	>	* ClassCastException}.
1027	>	*
1028	>	* @return a task, or {@code null} if none are available
1029		*/
1030	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
1031	<	Throwable ex = null;
1032	<	int last = tasks.length - 1;
734	<	for (int i = last; i >= 0; --i) {
735	<	ForkJoinTask<?> t = tasks[i];
736	<	if (t == null) {
737	<	if (ex == null)
738	<	ex = new NullPointerException();
739	<	}
740	<	else if (i != 0)
741	<	t.fork();
742	<	else {
743	<	t.quietlyInvoke();
744	<	if (ex == null)
745	<	ex = t.getException();
746	<	}
747	<	}
748	<	for (int i = 1; i <= last; ++i) {
749	<	ForkJoinTask<?> t = tasks[i];
750	<	if (t != null) {
751	<	if (ex != null)
752	<	t.cancel(false);
753	<	else {
754	<	t.quietlyJoin();
755	<	if (ex == null)
756	<	ex = t.getException();
757	<	}
758	<	}
759	<	}
760	<	if (ex != null)
761	<	rethrowException(ex);
1030	>	protected static ForkJoinTask<?> pollTask() {
1031	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1032	>	.pollTask();
1033		}
1034
1035		/**
1036	<	* Forks all tasks in the collection, returning when
1037	<	* <tt>isDone</tt> holds for all of them. If any task encounters
1038	<	* an exception, others may be cancelled.  This method may be
768	<	* invoked only from within other ForkJoinTask
769	<	* computations. Attempts to invoke in other contexts result in
770	<	* exceptions or errors including ClassCastException.
771	<	* @param tasks the collection of tasks
772	<	* @throws NullPointerException if tasks or any element are null.
773	<	* @throws RuntimeException or Error if any task did so.
1036	>	* Adaptor for Runnables. This implements RunnableFuture
1037	>	* to be compliant with AbstractExecutorService constraints
1038	>	* when used in ForkJoinPool.
1039		*/
1040	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
1041	<	if (!(tasks instanceof List)) {
1042	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
1043	<	return;
1044	<	}
1045	<	List<? extends ForkJoinTask<?>> ts =
1046	<	(List<? extends ForkJoinTask<?>>)tasks;
1047	<	Throwable ex = null;
1048	<	int last = ts.size() - 1;
784	<	for (int i = last; i >= 0; --i) {
785	<	ForkJoinTask<?> t = ts.get(i);
786	<	if (t == null) {
787	<	if (ex == null)
788	<	ex = new NullPointerException();
789	<	}
790	<	else if (i != 0)
791	<	t.fork();
792	<	else {
793	<	t.quietlyInvoke();
794	<	if (ex == null)
795	<	ex = t.getException();
796	<	}
1040	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1041	>	implements RunnableFuture<T> {
1042	>	final Runnable runnable;
1043	>	final T resultOnCompletion;
1044	>	T result;
1045	>	AdaptedRunnable(Runnable runnable, T result) {
1046	>	if (runnable == null) throw new NullPointerException();
1047	>	this.runnable = runnable;
1048	>	this.resultOnCompletion = result;
1049		}
1050	<	for (int i = 1; i <= last; ++i) {
1051	<	ForkJoinTask<?> t = ts.get(i);
1052	<	if (t != null) {
1053	<	if (ex != null)
1054	<	t.cancel(false);
1055	<	else {
804	<	t.quietlyJoin();
805	<	if (ex == null)
806	<	ex = t.getException();
807	<	}
808	<	}
1050	>	public T getRawResult() { return result; }
1051	>	public void setRawResult(T v) { result = v; }
1052	>	public boolean exec() {
1053	>	runnable.run();
1054	>	result = resultOnCompletion;
1055	>	return true;
1056		}
1057	<	if (ex != null)
1058	<	rethrowException(ex);
1057	>	public void run() { invoke(); }
1058	>	private static final long serialVersionUID = 5232453952276885070L;
1059		}
1060
1061		/**
1062	<	* Possibly executes tasks until the pool hosting the current task
816	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
817	<	* designs in which many tasks are forked, but none are explicitly
818	<	* joined, instead executing them until all are processed.
1062	>	* Adaptor for Callables
1063		*/
1064	<	public static void helpQuiesce() {
1065	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1066	<	helpQuiescePool();
1064	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1065	>	implements RunnableFuture<T> {
1066	>	final Callable<? extends T> callable;
1067	>	T result;
1068	>	AdaptedCallable(Callable<? extends T> callable) {
1069	>	if (callable == null) throw new NullPointerException();
1070	>	this.callable = callable;
1071	>	}
1072	>	public T getRawResult() { return result; }
1073	>	public void setRawResult(T v) { result = v; }
1074	>	public boolean exec() {
1075	>	try {
1076	>	result = callable.call();
1077	>	return true;
1078	>	} catch (Error err) {
1079	>	throw err;
1080	>	} catch (RuntimeException rex) {
1081	>	throw rex;
1082	>	} catch (Exception ex) {
1083	>	throw new RuntimeException(ex);
1084	>	}
1085	>	}
1086	>	public void run() { invoke(); }
1087	>	private static final long serialVersionUID = 2838392045355241008L;
1088		}
1089
1090		/**
1091	<	* Returns a estimate of how many more locally queued tasks are
1092	<	* held by the current worker thread than there are other worker
1093	<	* threads that might want to steal them.  This value may be
1094	<	* useful for heuristic decisions about whether to fork other
1095	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
1096	<	* worker should aim to maintain a small constant surplus (for
832	<	* example, 3) of tasks, and to process computations locally if
833	<	* this threshold is exceeded.
834	<	* @return the surplus number of tasks, which may be negative
1091	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1092	>	* method of the given {@code Runnable} as its action, and returns
1093	>	* a null result upon {@link #join}.
1094	>	*
1095	>	* @param runnable the runnable action
1096	>	* @return the task
1097		*/
1098	<	public static int surplus() {
1099	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
838	<	.getEstimatedSurplusTaskCount();
1098	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1099	>	return new AdaptedRunnable<Void>(runnable, null);
1100		}
1101
841	–	// Extension kit
842	–
1102		/**
1103	<	* Returns the result that would be returned by <tt>join</tt>, or
1104	<	* null if this task is not known to have been completed.  This
1105	<	* method is designed to aid debugging, as well as to support
847	<	* extensions. Its use in any other context is discouraged.
1103	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1104	>	* method of the given {@code Runnable} as its action, and returns
1105	>	* the given result upon {@link #join}.
1106		*
1107	<	* @return the result, or null if not completed.
1107	>	* @param runnable the runnable action
1108	>	* @param result the result upon completion
1109	>	* @return the task
1110		*/
1111	<	public abstract V getRawResult();
1111	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1112	>	return new AdaptedRunnable<T>(runnable, result);
1113	>	}
1114
1115		/**
1116	<	* Forces the given value to be returned as a result.  This method
1117	<	* is designed to support extensions, and should not in general be
1118	<	* called otherwise.
1116	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1117	>	* method of the given {@code Callable} as its action, and returns
1118	>	* its result upon {@link #join}, translating any checked exceptions
1119	>	* encountered into {@code RuntimeException}.
1120		*
1121	<	* @param value the value
1122	<	*/
860	<	protected abstract void setRawResult(V value);
861	<
862	<	/**
863	<	* Immediately performs the base action of this task.  This method
864	<	* is designed to support extensions, and should not in general be
865	<	* called otherwise. The return value controls whether this task
866	<	* is considered to be done normally. It may return false in
867	<	* asynchronous actions that require explicit invocations of
868	<	* <tt>complete</tt> to become joinable. It may throw exceptions
869	<	* to indicate abnormal exit.
870	<	* @return true if completed normally
871	<	* @throws Error or RuntimeException if encountered during computation
1121	>	* @param callable the callable action
1122	>	* @return the task
1123		*/
1124	<	protected abstract boolean exec();
1124	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1125	>	return new AdaptedCallable<T>(callable);
1126	>	}
1127
1128		// Serialization support
1129
1130		private static final long serialVersionUID = -7721805057305804111L;
1131
1132		/**
1133	<	* Save the state to a stream.
1133	>	* Saves the state to a stream (that is, serializes it).
1134		*
1135		* @serialData the current run status and the exception thrown
1136	<	* during execution, or null if none.
1136	>	* during execution, or {@code null} if none
1137		* @param s the stream
1138		*/
1139		private void writeObject(java.io.ObjectOutputStream s)
#	Line 890 | Line 1143 | public abstract class ForkJoinTask<V> im
1143		}
1144
1145		/**
1146	<	* Reconstitute the instance from a stream.
1146	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1147	>	*
1148		* @param s the stream
1149		*/
1150		private void readObject(java.io.ObjectInputStream s)
1151		throws java.io.IOException, ClassNotFoundException {
1152		s.defaultReadObject();
899	–	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1153		Object ex = s.readObject();
1154		if (ex != null)
1155	<	setDoneExceptionally((Throwable)ex);
1155	>	setExceptionalCompletion((Throwable) ex);
1156		}
1157
1158	<	// Temporary Unsafe mechanics for preliminary release
1158	>	// Unsafe mechanics
1159
1160	<	static final Unsafe _unsafe;
1161	<	static final long statusOffset;
1160	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1161	>	private static final long statusOffset =
1162	>	objectFieldOffset("status", ForkJoinTask.class);
1163
1164	<	static {
1164	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1165		try {
1166	<	if (ForkJoinTask.class.getClassLoader() != null) {
1167	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1168	<	f.setAccessible(true);
1169	<	_unsafe = (Unsafe)f.get(null);
1170	<	}
1171	<	else
1172	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
920	<	(ForkJoinTask.class.getDeclaredField("status"));
921	<	} catch (Exception ex) { throw new Error(ex); }
1166	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1167	>	} catch (NoSuchFieldException e) {
1168	>	// Convert Exception to corresponding Error
1169	>	NoSuchFieldError error = new NoSuchFieldError(field);
1170	>	error.initCause(e);
1171	>	throw error;
1172	>	}
1173		}
1174
1175	+	/**
1176	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1177	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1178	+	* into a jdk.
1179	+	*
1180	+	* @return a sun.misc.Unsafe
1181	+	*/
1182	+	private static sun.misc.Unsafe getUnsafe() {
1183	+	try {
1184	+	return sun.misc.Unsafe.getUnsafe();
1185	+	} catch (SecurityException se) {
1186	+	try {
1187	+	return java.security.AccessController.doPrivileged
1188	+	(new java.security
1189	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1190	+	public sun.misc.Unsafe run() throws Exception {
1191	+	java.lang.reflect.Field f = sun.misc
1192	+	.Unsafe.class.getDeclaredField("theUnsafe");
1193	+	f.setAccessible(true);
1194	+	return (sun.misc.Unsafe) f.get(null);
1195	+	}});
1196	+	} catch (java.security.PrivilegedActionException e) {
1197	+	throw new RuntimeException("Could not initialize intrinsics",
1198	+	e.getCause());
1199	+	}
1200	+	}
1201	+	}
1202		}

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