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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 1.63 by dl, Sat Sep 18 12:10:21 2010 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import java.io.Serializable;
9	<	import java.util.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.atomic.*;
11	<	import sun.misc.Unsafe;
12	<	import java.lang.reflect.*;
10	>	import java.io.Serializable;
11	>	import java.util.Collection;
12	>	import java.util.Collections;
13	>	import java.util.List;
14	>	import java.util.RandomAccess;
15	>	import java.util.Map;
16	>	import java.util.WeakHashMap;
17
18		/**
19	<	* Abstract base class for tasks that run within a ForkJoinPool.  A
20	<	* ForkJoinTask is a thread-like entity that is much lighter weight
21	<	* than a normal thread.  Huge numbers of tasks and subtasks may be
22	<	* hosted by a small number of actual threads in a ForkJoinPool,
23	<	* at the price of some usage limitations.
19	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
20	>	* A {@code ForkJoinTask} is a thread-like entity that is much
21	>	* lighter weight than a normal thread.  Huge numbers of tasks and
22	>	* subtasks may be hosted by a small number of actual threads in a
23	>	* ForkJoinPool, at the price of some usage limitations.
24	>	*
25	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
26	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
27	>	* start other subtasks.  As indicated by the name of this class,
28	>	* many programs using {@code ForkJoinTask} employ only methods
29	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
30	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
31	>	* provides a number of other methods that can come into play in
32	>	* advanced usages, as well as extension mechanics that allow
33	>	* support of new forms of fork/join processing.
34		*
35	<	* <p> ForkJoinTasks are forms of <tt>Futures</tt> supporting a
36	<	* limited range of use.  The "lightness" of ForkJoinTasks is due to a
37	<	* set of restrictions (that are only partially statically
38	<	* enforceable) reflecting their intended use as computational tasks
39	<	* calculating pure functions or operating on purely isolated objects.
40	<	* The primary coordination mechanisms supported for ForkJoinTasks are
41	<	* <tt>fork</tt>, that arranges asynchronous execution, and
42	<	* <tt>join</tt>, that doesn't proceed until the task's result has
43	<	* been computed. (Cancellation is also supported).  The computation
44	<	* defined in the <tt>compute</tt> method should avoid
45	<	* <tt>synchronized</tt> methods or blocks, and should minimize
46	<	* blocking synchronization apart from joining other tasks or using
47	<	* synchronizers such as Phasers that are advertised to cooperate with
48	<	* fork/join scheduling. Tasks should also not perform blocking IO,
49	<	* and should ideally access variables that are completely independent
50	<	* of those accessed by other running tasks. Minor breaches of these
51	<	* restrictions, for example using shared output streams, may be
52	<	* tolerable in practice, but frequent use may result in poor
53	<	* performance, and the potential to indefinitely stall if the number
54	<	* of threads not waiting for external synchronization becomes
55	<	* exhausted. This usage restriction is in part enforced by not
56	<	* permitting checked exceptions such as IOExceptions to be
57	<	* thrown. However, computations may still encounter unchecked
58	<	* exceptions, that are rethrown to callers attempting join
59	<	* them. These exceptions may additionally include
60	<	* RejectedExecutionExceptions stemming from internal resource
48	<	* exhaustion such as failure to allocate internal task queues.
35	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
36	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
37	>	* restrictions (that are only partially statically enforceable)
38	>	* reflecting their intended use as computational tasks calculating
39	>	* pure functions or operating on purely isolated objects.  The
40	>	* primary coordination mechanisms are {@link #fork}, that arranges
41	>	* asynchronous execution, and {@link #join}, that doesn't proceed
42	>	* until the task's result has been computed.  Computations should
43	>	* avoid {@code synchronized} methods or blocks, and should minimize
44	>	* other blocking synchronization apart from joining other tasks or
45	>	* using synchronizers such as Phasers that are advertised to
46	>	* cooperate with fork/join scheduling. Tasks should also not perform
47	>	* blocking IO, and should ideally access variables that are
48	>	* completely independent of those accessed by other running
49	>	* tasks. Minor breaches of these restrictions, for example using
50	>	* shared output streams, may be tolerable in practice, but frequent
51	>	* use may result in poor performance, and the potential to
52	>	* indefinitely stall if the number of threads not waiting for IO or
53	>	* other external synchronization becomes exhausted. This usage
54	>	* restriction is in part enforced by not permitting checked
55	>	* exceptions such as {@code IOExceptions} to be thrown. However,
56	>	* computations may still encounter unchecked exceptions, that are
57	>	* rethrown to callers attempting to join them. These exceptions may
58	>	* additionally include {@link RejectedExecutionException} stemming
59	>	* from internal resource exhaustion, such as failure to allocate
60	>	* internal task queues.
61		*
62	<	* <p> The <tt>ForkJoinTask</tt> class is not usually directly
63	<	* subclassed.  Instead, you subclass one of the abstract classes that
64	<	* support different styles of fork/join processing.  Normally, a
65	<	* concrete ForkJoinTask subclass declares fields comprising its
66	<	* parameters, established in a constructor, and then defines a
67	<	* <tt>compute</tt> method that somehow uses the control methods
68	<	* supplied by this base class. While these methods have
69	<	* <tt>public</tt> access, some of them may only be called from within
70	<	* other ForkJoinTasks. Attempts to invoke them in other contexts
71	<	* result in exceptions or errors including ClassCastException.  The
72	<	* only way to invoke a "main" driver task is to submit it to a
73	<	* ForkJoinPool. Once started, this will usually in turn start other
74	<	* subtasks.
62	>	* <p>The primary method for awaiting completion and extracting
63	>	* results of a task is {@link #join}, but there are several variants:
64	>	* The {@link Future#get} methods support interruptible and/or timed
65	>	* waits for completion and report results using {@code Future}
66	>	* conventions. Method {@link #invoke} is semantically
67	>	* equivalent to {@code fork(); join()} but always attempts to begin
68	>	* execution in the current thread. The "<em>quiet</em>" forms of
69	>	* these methods do not extract results or report exceptions. These
70	>	* may be useful when a set of tasks are being executed, and you need
71	>	* to delay processing of results or exceptions until all complete.
72	>	* Method {@code invokeAll} (available in multiple versions)
73	>	* performs the most common form of parallel invocation: forking a set
74	>	* of tasks and joining them all.
75		*
76	<	* <p>Most base support methods are <tt>final</tt> because their
77	<	* implementations are intrinsically tied to the underlying
78	<	* lightweight task scheduling framework, and so cannot be overridden.
79	<	* Developers creating new basic styles of fork/join processing should
80	<	* minimally implement protected methods <tt>exec</tt>,
81	<	* <tt>setRawResult</tt>, and <tt>getRawResult</tt>, while also
82	<	* introducing an abstract computational method that can be
83	<	* implemented in its subclasses. To support such extensions,
84	<	* instances of ForkJoinTasks maintain an atomically updated
85	<	* <tt>short</tt> representing user-defined control state.  Control
86	<	* state is guaranteed initially to be zero, and to be negative upon
87	<	* completion, but may otherwise be used for any other control
88	<	* purposes, such as maintaining join counts.  The {@link
89	<	* ForkJoinWorkerThread} class supports additional inspection and
90	<	* tuning methods that can be useful when developing extensions.
76	>	* <p>The execution status of tasks may be queried at several levels
77	>	* of detail: {@link #isDone} is true if a task completed in any way
78	>	* (including the case where a task was cancelled without executing);
79	>	* {@link #isCompletedNormally} is true if a task completed without
80	>	* cancellation or encountering an exception; {@link #isCancelled} is
81	>	* true if the task was cancelled (in which case {@link #getException}
82	>	* returns a {@link java.util.concurrent.CancellationException}); and
83	>	* {@link #isCompletedAbnormally} is true if a task was either
84	>	* cancelled or encountered an exception, in which case {@link
85	>	* #getException} will return either the encountered exception or
86	>	* {@link java.util.concurrent.CancellationException}.
87	>	*
88	>	* <p>The ForkJoinTask class is not usually directly subclassed.
89	>	* Instead, you subclass one of the abstract classes that support a
90	>	* particular style of fork/join processing, typically {@link
91	>	* RecursiveAction} for computations that do not return results, or
92	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
93	>	* ForkJoinTask subclass declares fields comprising its parameters,
94	>	* established in a constructor, and then defines a {@code compute}
95	>	* method that somehow uses the control methods supplied by this base
96	>	* class. While these methods have {@code public} access (to allow
97	>	* instances of different task subclasses to call each other's
98	>	* methods), some of them may only be called from within other
99	>	* ForkJoinTasks (as may be determined using method {@link
100	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
101	>	* result in exceptions or errors, possibly including
102	>	* {@code ClassCastException}.
103	>	*
104	>	* <p>Most base support methods are {@code final}, to prevent
105	>	* overriding of implementations that are intrinsically tied to the
106	>	* underlying lightweight task scheduling framework.  Developers
107	>	* creating new basic styles of fork/join processing should minimally
108	>	* implement {@code protected} methods {@link #exec}, {@link
109	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
110	>	* an abstract computational method that can be implemented in its
111	>	* subclasses, possibly relying on other {@code protected} methods
112	>	* provided by this class.
113		*
114		* <p>ForkJoinTasks should perform relatively small amounts of
115	<	* computations, othewise splitting into smaller tasks. As a very
116	<	* rough rule of thumb, a task should perform more than 100 and less
117	<	* than 10000 basic computational steps. If tasks are too big, then
118	<	* parellelism cannot improve throughput. If too small, then memory
119	<	* and internal task maintenance overhead may overwhelm processing.
115	>	* computation. Large tasks should be split into smaller subtasks,
116	>	* usually via recursive decomposition. As a very rough rule of thumb,
117	>	* a task should perform more than 100 and less than 10000 basic
118	>	* computational steps. If tasks are too big, then parallelism cannot
119	>	* improve throughput. If too small, then memory and internal task
120	>	* maintenance overhead may overwhelm processing.
121	>	*
122	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
123	>	* and {@link Callable}, that may be of use when mixing execution of
124	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
125	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
126	>	*
127	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
128	>	* used in extensions such as remote execution frameworks. It is
129	>	* sensible to serialize tasks only before or after, but not during,
130	>	* execution. Serialization is not relied on during execution itself.
131		*
132	<	* <p>ForkJoinTasks are <tt>Serializable</tt>, which enables them to
133	<	* be used in extensions such as remote execution frameworks. However,
89	<	* it is in general safe to serialize tasks only before or after, but
90	<	* not during execution. Serialization is not relied on during
91	<	* execution itself.
132	>	* @since 1.7
133	>	* @author Doug Lea
134		*/
135		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
136	<	/**
137	<	* Status field holding all run status. We pack this into a single
138	<	* int both to minimize footprint overhead and to ensure atomicity
139	<	* (updates are via CAS).
140	<	*
141	<	* Status is initially zero, and takes on nonnegative values until
142	<	* completed, upon which status holds COMPLETED. CANCELLED, or
143	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
144	<	* blocking waits by other threads have SIGNAL_MASK bits set --
145	<	* bit 15 for external (nonFJ) waits, and the rest a count of
146	<	* waiting FJ threads.  (This representation relies on
147	<	* ForkJoinPool max thread limits). Completion of a stolen task
148	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
149	<	* though suboptimal for some purposes, we use basic builtin
150	<	* wait/notify to take advantage of "monitor inflation" in JVMs
151	<	* that we would otherwise need to emulate to avoid adding further
152	<	* per-task bookkeeping overhead. Note that bits 16-28 are
153	<	* currently unused. Also value 0x80000000 is available as spare
154	<	* completion value.
155	<	*/
156	<	volatile int status; // accessed directy by pool and workers
157	<
158	<	static final int COMPLETION_MASK      = 0xe0000000;
159	<	static final int NORMAL               = 0xe0000000; // == mask
160	<	static final int CANCELLED            = 0xc0000000;
161	<	static final int EXCEPTIONAL          = 0xa0000000;
162	<	static final int SIGNAL_MASK          = 0x0000ffff;
163	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
164	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
136	>
137	>	/*
138	>	* See the internal documentation of class ForkJoinPool for a
139	>	* general implementation overview.  ForkJoinTasks are mainly
140	>	* responsible for maintaining their "status" field amidst relays
141	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
142	>	* methods of this class are more-or-less layered into (1) basic
143	>	* status maintenance (2) execution and awaiting completion (3)
144	>	* user-level methods that additionally report results. This is
145	>	* sometimes hard to see because this file orders exported methods
146	>	* in a way that flows well in javadocs. In particular, most
147	>	* join mechanics are in method quietlyJoin, below.
148	>	*/
149	>
150	>	/*
151	>	* The status field holds run control status bits packed into a
152	>	* single int to minimize footprint and to ensure atomicity (via
153	>	* CAS).  Status is initially zero, and takes on nonnegative
154	>	* values until completed, upon which status holds value
155	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
156	>	* waits by other threads have the SIGNAL bit set.  Completion of
157	>	* a stolen task with SIGNAL set awakens any waiters via
158	>	* notifyAll. Even though suboptimal for some purposes, we use
159	>	* basic builtin wait/notify to take advantage of "monitor
160	>	* inflation" in JVMs that we would otherwise need to emulate to
161	>	* avoid adding further per-task bookkeeping overhead.  We want
162	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
163	>	* techniques, so use some odd coding idioms that tend to avoid
164	>	* them.
165	>	*/
166	>
167	>	/** The run status of this task */
168	>	volatile int status; // accessed directly by pool and workers
169	>
170	>	private static final int NORMAL      = -1;
171	>	private static final int CANCELLED   = -2;
172	>	private static final int EXCEPTIONAL = -3;
173	>	private static final int SIGNAL      =  1;
174
175		/**
176		* Table of exceptions thrown by tasks, to enable reporting by
177		* callers. Because exceptions are rare, we don't directly keep
178	<	* them with task objects, but instead us a weak ref table.  Note
178	>	* them with task objects, but instead use a weak ref table.  Note
179		* that cancellation exceptions don't appear in the table, but are
180		* instead recorded as status values.
181	<	* Todo: Use ConcurrentReferenceHashMap
181	>	* TODO: Use ConcurrentReferenceHashMap
182		*/
183		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
184		Collections.synchronizedMap
185		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
186
187	<	// within-package utilities
137	<
138	<	/**
139	<	* Get current worker thread, or null if not a worker thread
140	<	*/
141	<	static ForkJoinWorkerThread getWorker() {
142	<	Thread t = Thread.currentThread();
143	<	return ((t instanceof ForkJoinWorkerThread)?
144	<	(ForkJoinWorkerThread)t : null);
145	<	}
146	<
147	<	/**
148	<	* Get pool of current worker thread, or null if not a worker thread
149	<	*/
150	<	static ForkJoinPool getWorkerPool() {
151	<	Thread t = Thread.currentThread();
152	<	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);
158	<	}
187	>	// Maintaining completion status
188
189		/**
190	<	* Workaround for not being able to rethrow unchecked exceptions.
191	<	*/
192	<	static void rethrowException(Throwable ex) {
164	<	if (ex != null)
165	<	_unsafe.throwException(ex);
166	<	}
167	<
168	<	// Setting completion status
169	<
170	<	/**
171	<	* Mark completion and wake up threads waiting to join this task.
190	>	* Marks completion and wakes up threads waiting to join this task,
191	>	* also clearing signal request bits.
192	>	*
193		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
194		*/
195	<	final void setCompletion(int completion) {
196	<	ForkJoinPool pool = getWorkerPool();
197	<	if (pool != null) {
198	<	int s; // Clear signal bits while setting completion status
199	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
200	<
201	<	if ((s & SIGNAL_MASK) != 0) {
181	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
182	<	pool.updateRunningCount(s);
183	<	synchronized(this) { notifyAll(); }
195	>	private void setCompletion(int completion) {
196	>	int s;
197	>	while ((s = status) >= 0) {
198	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
199	>	if (s != 0)
200	>	synchronized (this) { notifyAll(); }
201	>	break;
202		}
203		}
186	–	else
187	–	externallySetCompletion(completion);
188	–	}
189	–
190	–	/**
191	–	* Version of setCompletion for non-FJ threads.  Leaves signal
192	–	* bits for unblocked threads to adjust, and always notifies.
193	–	*/
194	–	private void externallySetCompletion(int completion) {
195	–	int s;
196	–	do;while ((s = status) >= 0 &&
197	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
198	–	synchronized(this) { notifyAll(); }
204		}
205
206		/**
207	<	* Sets status to indicate normal completion
208	<	*/
209	<	final void setNormalCompletion() {
205	<	// Try typical fast case -- single CAS, no signal, not already done.
206	<	// Manually expand casStatus to improve chances of inlining it
207	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
208	<	setCompletion(NORMAL);
209	<	}
210	<
211	<	// internal waiting and notification
212	<
213	<	/**
214	<	* Performs the actual monitor wait for awaitDone
207	>	* Records exception and sets exceptional completion.
208	>	*
209	>	* @return status on exit
210		*/
211	<	private void doAwaitDone() {
212	<	// Minimize lock bias and in/de-flation effects by maximizing
213	<	// chances of waiting inside sync
219	<	try {
220	<	while (status >= 0)
221	<	synchronized(this) { if (status >= 0) wait(); }
222	<	} catch (InterruptedException ie) {
223	<	onInterruptedWait();
224	<	}
211	>	private void setExceptionalCompletion(Throwable rex) {
212	>	exceptionMap.put(this, rex);
213	>	setCompletion(EXCEPTIONAL);
214		}
215
216		/**
217	<	* Performs the actual monitor wait for awaitDone
217	>	* Blocks a worker thread until completion. Called only by
218	>	* pool. Currently unused -- pool-based waits use timeout
219	>	* version below.
220		*/
221	<	private void doAwaitDone(long startTime, long nanos) {
222	<	synchronized(this) {
221	>	final void internalAwaitDone() {
222	>	int s;         // the odd construction reduces lock bias effects
223	>	while ((s = status) >= 0) {
224		try {
225	<	while (status >= 0) {
226	<	long nt = nanos - System.nanoTime() - startTime;
227	<	if (nt <= 0)
236	<	break;
237	<	wait(nt / 1000000, (int)(nt % 1000000));
225	>	synchronized (this) {
226	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
227	>	wait();
228		}
229		} catch (InterruptedException ie) {
230	<	onInterruptedWait();
230	>	cancelIfTerminating();
231		}
232		}
233		}
234
245	–	// Awaiting completion
246	–
235		/**
236	<	* Sets status to indicate there is joiner, then waits for join,
237	<	* surrounded with pool notifications.
238	<	* @return status upon exit
236	>	* Blocks a worker thread until completed or timed out.  Called
237	>	* only by pool.
238	>	*
239	>	* @return status on exit
240		*/
241	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
253	<	ForkJoinPool pool = w == null? null : w.pool;
241	>	final int internalAwaitDone(long millis) {
242		int s;
243	<	while ((s = status) >= 0) {
244	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
245	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
246	<	doAwaitDone();
247	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
248	<	adjustPoolCountsOnUnblock(pool);
249	<	break;
243	>	if ((s = status) >= 0) {
244	>	try {
245	>	synchronized (this) {
246	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
247	>	wait(millis, 0);
248	>	}
249	>	} catch (InterruptedException ie) {
250	>	cancelIfTerminating();
251		}
252	+	s = status;
253		}
254		return s;
255		}
256
257		/**
258	<	* Timed version of awaitDone
269	<	* @return status upon exit
258	>	* Blocks a non-worker-thread until completion.
259		*/
260	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
272	<	ForkJoinPool pool = w == null? null : w.pool;
260	>	private void externalAwaitDone() {
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);
267	<	if ((s = status) >= 0) {
268	<	adjustPoolCountsOnCancelledWait(pool);
269	<	s = status;
263	>	synchronized (this) {
264	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
265	>	boolean interrupted = false;
266	>	while (status >= 0) {
267	>	try {
268	>	wait();
269	>	} catch (InterruptedException ie) {
270	>	interrupted = true;
271	>	}
272	>	}
273	>	if (interrupted)
274	>	Thread.currentThread().interrupt();
275	>	break;
276		}
283	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
284	–	adjustPoolCountsOnUnblock(pool);
285	–	break;
277		}
278		}
288	–	return s;
279		}
280
281		/**
282	<	* Notify pool that thread is unblocked. Called by signalled
283	<	* threads when woken by non-FJ threads (which is atypical).
282	>	* Unless done, calls exec and records status if completed, but
283	>	* doesn't wait for completion otherwise. Primary execution method
284	>	* for ForkJoinWorkerThread.
285		*/
286	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
287	<	int s;
288	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
289	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
290	<	pool.updateRunningCount(s);
286	>	final void quietlyExec() {
287	>	try {
288	>	if (status < 0 || !exec())
289	>	return;
290	>	} catch (Throwable rex) {
291	>	setExceptionalCompletion(rex);
292	>	return;
293	>	}
294	>	setCompletion(NORMAL); // must be outside try block
295		}
296
297	+	// public methods
298	+
299		/**
300	<	* Notify pool to adjust counts on cancelled or timed out wait
300	>	* Arranges to asynchronously execute this task.  While it is not
301	>	* necessarily enforced, it is a usage error to fork a task more
302	>	* than once unless it has completed and been reinitialized.
303	>	* Subsequent modifications to the state of this task or any data
304	>	* it operates on are not necessarily consistently observable by
305	>	* any thread other than the one executing it unless preceded by a
306	>	* call to {@link #join} or related methods, or a call to {@link
307	>	* #isDone} returning {@code true}.
308	>	*
309	>	* <p>This method may be invoked only from within {@code
310	>	* ForkJoinTask} computations (as may be determined using method
311	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
312	>	* result in exceptions or errors, possibly including {@code
313	>	* ClassCastException}.
314	>	*
315	>	* @return {@code this}, to simplify usage
316		*/
317	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
318	<	if (pool != null) {
319	<	int s;
320	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
309	<	if (casStatus(s, s - 1)) {
310	<	pool.updateRunningCount(1);
311	<	break;
312	<	}
313	<	}
314	<	}
317	>	public final ForkJoinTask<V> fork() {
318	>	((ForkJoinWorkerThread) Thread.currentThread())
319	>	.pushTask(this);
320	>	return this;
321		}
322
323	<	private void onInterruptedWait() {
324	<	Thread t = Thread.currentThread();
325	<	if (t instanceof ForkJoinWorkerThread) {
326	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)t;
327	<	if (w.isTerminating())
328	<	cancelIgnoreExceptions();
329	<	}
330	<	else { // re-interrupt
331	<	try {
332	<	t.interrupt();
333	<	} catch (SecurityException ignore) {
334	<	}
335	<	}
323	>	/**
324	>	* Returns the result of the computation when it {@link #isDone is done}.
325	>	* This method differs from {@link #get()} in that
326	>	* abnormal completion results in {@code RuntimeException} or
327	>	* {@code Error}, not {@code ExecutionException}.
328	>	*
329	>	* @return the computed result
330	>	*/
331	>	public final V join() {
332	>	quietlyJoin();
333	>	Throwable ex;
334	>	if (status < NORMAL && (ex = getException()) != null)
335	>	UNSAFE.throwException(ex);
336	>	return getRawResult();
337		}
338
339	<	// Recording and reporting exceptions
339	>	/**
340	>	* Commences performing this task, awaits its completion if
341	>	* necessary, and returns its result, or throws an (unchecked)
342	>	* {@code RuntimeException} or {@code Error} if the underlying
343	>	* computation did so.
344	>	*
345	>	* @return the computed result
346	>	*/
347	>	public final V invoke() {
348	>	quietlyInvoke();
349	>	Throwable ex;
350	>	if (status < NORMAL && (ex = getException()) != null)
351	>	UNSAFE.throwException(ex);
352	>	return getRawResult();
353	>	}
354
355	<	private void setDoneExceptionally(Throwable rex) {
356	<	exceptionMap.put(this, rex);
357	<	setCompletion(EXCEPTIONAL);
355	>	/**
356	>	* Forks the given tasks, returning when {@code isDone} holds for
357	>	* each task or an (unchecked) exception is encountered, in which
358	>	* case the exception is rethrown. If more than one task
359	>	* encounters an exception, then this method throws any one of
360	>	* these exceptions. If any task encounters an exception, the
361	>	* other may be cancelled. However, the execution status of
362	>	* individual tasks is not guaranteed upon exceptional return. The
363	>	* status of each task may be obtained using {@link
364	>	* #getException()} and related methods to check if they have been
365	>	* cancelled, completed normally or exceptionally, or left
366	>	* unprocessed.
367	>	*
368	>	* <p>This method may be invoked only from within {@code
369	>	* ForkJoinTask} computations (as may be determined using method
370	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
371	>	* result in exceptions or errors, possibly including {@code
372	>	* ClassCastException}.
373	>	*
374	>	* @param t1 the first task
375	>	* @param t2 the second task
376	>	* @throws NullPointerException if any task is null
377	>	*/
378	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
379	>	t2.fork();
380	>	t1.invoke();
381	>	t2.join();
382		}
383
384		/**
385	<	* Throws the exception associated with status s;
386	<	* @throws the exception
385	>	* Forks the given tasks, returning when {@code isDone} holds for
386	>	* each task or an (unchecked) exception is encountered, in which
387	>	* case the exception is rethrown. If more than one task
388	>	* encounters an exception, then this method throws any one of
389	>	* these exceptions. If any task encounters an exception, others
390	>	* may be cancelled. However, the execution status of individual
391	>	* tasks is not guaranteed upon exceptional return. The status of
392	>	* each task may be obtained using {@link #getException()} and
393	>	* related methods to check if they have been cancelled, completed
394	>	* normally or exceptionally, or left unprocessed.
395	>	*
396	>	* <p>This method may be invoked only from within {@code
397	>	* ForkJoinTask} computations (as may be determined using method
398	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
399	>	* result in exceptions or errors, possibly including {@code
400	>	* ClassCastException}.
401	>	*
402	>	* @param tasks the tasks
403	>	* @throws NullPointerException if any task is null
404		*/
405	<	private void reportException(int s) {
406	<	if ((s &= COMPLETION_MASK) < NORMAL) {
407	<	if (s == CANCELLED)
408	<	throw new CancellationException();
409	<	else
410	<	rethrowException(exceptionMap.get(this));
405	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
406	>	Throwable ex = null;
407	>	int last = tasks.length - 1;
408	>	for (int i = last; i >= 0; --i) {
409	>	ForkJoinTask<?> t = tasks[i];
410	>	if (t == null) {
411	>	if (ex == null)
412	>	ex = new NullPointerException();
413	>	}
414	>	else if (i != 0)
415	>	t.fork();
416	>	else {
417	>	t.quietlyInvoke();
418	>	if (ex == null && t.status < NORMAL)
419	>	ex = t.getException();
420	>	}
421	>	}
422	>	for (int i = 1; i <= last; ++i) {
423	>	ForkJoinTask<?> t = tasks[i];
424	>	if (t != null) {
425	>	if (ex != null)
426	>	t.cancel(false);
427	>	else {
428	>	t.quietlyJoin();
429	>	if (ex == null && t.status < NORMAL)
430	>	ex = t.getException();
431	>	}
432	>	}
433		}
434	+	if (ex != null)
435	+	UNSAFE.throwException(ex);
436		}
437
438		/**
439	<	* Returns result or throws exception using j.u.c.Future conventions
440	<	* Only call when isDone known to be true.
439	>	* Forks all tasks in the specified collection, returning when
440	>	* {@code isDone} holds for each task or an (unchecked) exception
441	>	* is encountered, in which case the exception is rethrown. If
442	>	* more than one task encounters an exception, then this method
443	>	* throws any one of these exceptions. If any task encounters an
444	>	* exception, others may be cancelled. However, the execution
445	>	* status of individual tasks is not guaranteed upon exceptional
446	>	* return. The status of each task may be obtained using {@link
447	>	* #getException()} and related methods to check if they have been
448	>	* cancelled, completed normally or exceptionally, or left
449	>	* unprocessed.
450	>	*
451	>	* <p>This method may be invoked only from within {@code
452	>	* ForkJoinTask} computations (as may be determined using method
453	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
454	>	* result in exceptions or errors, possibly including {@code
455	>	* ClassCastException}.
456	>	*
457	>	* @param tasks the collection of tasks
458	>	* @return the tasks argument, to simplify usage
459	>	* @throws NullPointerException if tasks or any element are null
460		*/
461	<	private V reportFutureResult()
462	<	throws ExecutionException, InterruptedException {
463	<	int s = status & COMPLETION_MASK;
464	<	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();
461	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
462	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
463	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
464	>	return tasks;
465		}
466	<	return getRawResult();
466	>	@SuppressWarnings("unchecked")
467	>	List<? extends ForkJoinTask<?>> ts =
468	>	(List<? extends ForkJoinTask<?>>) tasks;
469	>	Throwable ex = null;
470	>	int last = ts.size() - 1;
471	>	for (int i = last; i >= 0; --i) {
472	>	ForkJoinTask<?> t = ts.get(i);
473	>	if (t == null) {
474	>	if (ex == null)
475	>	ex = new NullPointerException();
476	>	}
477	>	else if (i != 0)
478	>	t.fork();
479	>	else {
480	>	t.quietlyInvoke();
481	>	if (ex == null && t.status < NORMAL)
482	>	ex = t.getException();
483	>	}
484	>	}
485	>	for (int i = 1; i <= last; ++i) {
486	>	ForkJoinTask<?> t = ts.get(i);
487	>	if (t != null) {
488	>	if (ex != null)
489	>	t.cancel(false);
490	>	else {
491	>	t.quietlyJoin();
492	>	if (ex == null && t.status < NORMAL)
493	>	ex = t.getException();
494	>	}
495	>	}
496	>	}
497	>	if (ex != null)
498	>	UNSAFE.throwException(ex);
499	>	return tasks;
500		}
501
502		/**
503	<	* Returns result or throws exception using j.u.c.Future conventions
504	<	* with timeouts
503	>	* Attempts to cancel execution of this task. This attempt will
504	>	* fail if the task has already completed, has already been
505	>	* cancelled, or could not be cancelled for some other reason. If
506	>	* successful, and this task has not started when cancel is
507	>	* called, execution of this task is suppressed, {@link
508	>	* #isCancelled} will report true, and {@link #join} will result
509	>	* in a {@code CancellationException} being thrown.
510	>	*
511	>	* <p>This method may be overridden in subclasses, but if so, must
512	>	* still ensure that these minimal properties hold. In particular,
513	>	* the {@code cancel} method itself must not throw exceptions.
514	>	*
515	>	* <p>This method is designed to be invoked by <em>other</em>
516	>	* tasks. To terminate the current task, you can just return or
517	>	* throw an unchecked exception from its computation method, or
518	>	* invoke {@link #completeExceptionally}.
519	>	*
520	>	* @param mayInterruptIfRunning this value is ignored in the
521	>	* default implementation because tasks are not
522	>	* cancelled via interruption
523	>	*
524	>	* @return {@code true} if this task is now cancelled
525		*/
526	<	private V reportTimedFutureResult()
527	<	throws InterruptedException, ExecutionException, TimeoutException {
528	<	Throwable ex;
378	<	int s = status & COMPLETION_MASK;
379	<	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();
526	>	public boolean cancel(boolean mayInterruptIfRunning) {
527	>	setCompletion(CANCELLED);
528	>	return status == CANCELLED;
529		}
530
390	–	// internal execution methods
391	–
531		/**
532	<	* Calls exec, recording completion, and rethrowing exception if
533	<	* encountered. Caller should normally check status before calling
534	<	* @return true if completed normally
532	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
533	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
534	>	* exceptions, but if it does anyway, we have no recourse during
535	>	* shutdown, so guard against this case.
536		*/
537	<	private boolean tryExec() {
538	<	try { // try block must contain only call to exec
539	<	if (!exec())
540	<	return false;
401	<	} catch (Throwable rex) {
402	<	setDoneExceptionally(rex);
403	<	rethrowException(rex);
404	<	return false; // not reached
537	>	final void cancelIgnoringExceptions() {
538	>	try {
539	>	cancel(false);
540	>	} catch (Throwable ignore) {
541		}
406	–	setNormalCompletion();
407	–	return true;
542		}
543
544		/**
545	<	* Main execution method used by worker threads. Invokes
546	<	* base computation unless already complete
545	>	* Cancels if current thread is a terminating worker thread,
546	>	* ignoring any exceptions thrown by cancel.
547		*/
548	<	final void quietlyExec() {
549	<	if (status >= 0) {
548	>	final void cancelIfTerminating() {
549	>	Thread t = Thread.currentThread();
550	>	if ((t instanceof ForkJoinWorkerThread) &&
551	>	((ForkJoinWorkerThread) t).isTerminating()) {
552		try {
553	<	if (!exec())
554	<	return;
419	<	} catch(Throwable rex) {
420	<	setDoneExceptionally(rex);
421	<	return;
553	>	cancel(false);
554	>	} catch (Throwable ignore) {
555		}
423	–	setNormalCompletion();
556		}
557		}
558
559	<	/**
560	<	* Calls exec, recording but not rethrowing exception
561	<	* Caller should normally check status before calling
562	<	* @return true if completed normally
563	<	*/
564	<	private boolean tryQuietlyInvoke() {
433	<	try {
434	<	if (!exec())
435	<	return false;
436	<	} catch (Throwable rex) {
437	<	setDoneExceptionally(rex);
438	<	return false;
439	<	}
440	<	setNormalCompletion();
441	<	return true;
559	>	public final boolean isDone() {
560	>	return status < 0;
561	>	}
562	>
563	>	public final boolean isCancelled() {
564	>	return status == CANCELLED;
565		}
566
567		/**
568	<	* Cancel, ignoring any exceptions it throws
568	>	* Returns {@code true} if this task threw an exception or was cancelled.
569	>	*
570	>	* @return {@code true} if this task threw an exception or was cancelled
571		*/
572	<	final void cancelIgnoreExceptions() {
573	<	try {
449	<	cancel(false);
450	<	} catch(Throwable ignore) {
451	<	}
572	>	public final boolean isCompletedAbnormally() {
573	>	return status < NORMAL;
574		}
575
454	–	// public methods
455	–
576		/**
577	<	* Arranges to asynchronously execute this task.  While it is not
578	<	* necessarily enforced, it is a usage error to fork a task more
579	<	* than once unless it has completed and been reinitialized.  This
580	<	* method may be invoked only from within other ForkJoinTask
581	<	* computations. Attempts to invoke in other contexts result in
462	<	* exceptions or errors including ClassCastException.
577	>	* Returns {@code true} if this task completed without throwing an
578	>	* exception and was not cancelled.
579	>	*
580	>	* @return {@code true} if this task completed without throwing an
581	>	* exception and was not cancelled
582		*/
583	<	public final void fork() {
584	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
583	>	public final boolean isCompletedNormally() {
584	>	return status == NORMAL;
585		}
586
587		/**
588	<	* Returns the result of the computation when it is ready.
589	<	* This method differs from <tt>get</tt> in that abnormal
590	<	* completion results in RuntimeExceptions or Errors, not
472	<	* ExecutionExceptions.
588	>	* Returns the exception thrown by the base computation, or a
589	>	* {@code CancellationException} if cancelled, or {@code null} if
590	>	* none or if the method has not yet completed.
591		*
592	<	* @return the computed result
592	>	* @return the exception, or {@code null} if none
593		*/
594	<	public final V join() {
595	<	ForkJoinWorkerThread w = getWorker();
596	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
597	<	reportException(awaitDone(w, true));
598	<	return getRawResult();
594	>	public final Throwable getException() {
595	>	int s = status;
596	>	return ((s >= NORMAL)    ? null :
597	>	(s == CANCELLED) ? new CancellationException() :
598	>	exceptionMap.get(this));
599		}
600
601	<	public final V get() throws InterruptedException, ExecutionException {
602	<	ForkJoinWorkerThread w = getWorker();
603	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
604	<	awaitDone(w, true);
605	<	return reportFutureResult();
601	>	/**
602	>	* Completes this task abnormally, and if not already aborted or
603	>	* cancelled, causes it to throw the given exception upon
604	>	* {@code join} and related operations. This method may be used
605	>	* to induce exceptions in asynchronous tasks, or to force
606	>	* completion of tasks that would not otherwise complete.  Its use
607	>	* in other situations is discouraged.  This method is
608	>	* overridable, but overridden versions must invoke {@code super}
609	>	* implementation to maintain guarantees.
610	>	*
611	>	* @param ex the exception to throw. If this exception is not a
612	>	* {@code RuntimeException} or {@code Error}, the actual exception
613	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
614	>	*/
615	>	public void completeExceptionally(Throwable ex) {
616	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
617	>	(ex instanceof Error) ? ex :
618	>	new RuntimeException(ex));
619		}
620
621	<	public final V get(long timeout, TimeUnit unit)
622	<	throws InterruptedException, ExecutionException, TimeoutException {
623	<	ForkJoinWorkerThread w = getWorker();
624	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
625	<	awaitDone(w, unit.toNanos(timeout));
626	<	return reportTimedFutureResult();
621	>	/**
622	>	* Completes this task, and if not already aborted or cancelled,
623	>	* returning the given value as the result of subsequent
624	>	* invocations of {@code join} and related operations. This method
625	>	* may be used to provide results for asynchronous tasks, or to
626	>	* provide alternative handling for tasks that would not otherwise
627	>	* complete normally. Its use in other situations is
628	>	* discouraged. This method is overridable, but overridden
629	>	* versions must invoke {@code super} implementation to maintain
630	>	* guarantees.
631	>	*
632	>	* @param value the result value for this task
633	>	*/
634	>	public void complete(V value) {
635	>	try {
636	>	setRawResult(value);
637	>	} catch (Throwable rex) {
638	>	setExceptionalCompletion(rex);
639	>	return;
640	>	}
641	>	setCompletion(NORMAL);
642		}
643
644		/**
645	<	* Possibly executes other tasks until this task is ready, then
646	<	* returns the result of the computation.  This method may be more
647	<	* efficient than <tt>join</tt>, but is only applicable when there
502	<	* are no potemtial dependencies between continuation of the
503	<	* current task and that of any other task that might be executed
504	<	* while helping. (This usually holds for pure divide-and-conquer
505	<	* tasks).
645	>	* Waits if necessary for the computation to complete, and then
646	>	* retrieves its result.
647	>	*
648		* @return the computed result
649	+	* @throws CancellationException if the computation was cancelled
650	+	* @throws ExecutionException if the computation threw an
651	+	* exception
652	+	* @throws InterruptedException if the current thread is not a
653	+	* member of a ForkJoinPool and was interrupted while waiting
654		*/
655	<	public final V helpJoin() {
656	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
657	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
658	<	reportException(w.helpJoinTask(this));
655	>	public final V get() throws InterruptedException, ExecutionException {
656	>	int s;
657	>	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
658	>	quietlyJoin();
659	>	s = status;
660	>	}
661	>	else {
662	>	while ((s = status) >= 0) {
663	>	synchronized (this) { // interruptible form of awaitDone
664	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
665	>	s, SIGNAL)) {
666	>	while (status >= 0)
667	>	wait();
668	>	}
669	>	}
670	>	}
671	>	}
672	>	if (s < NORMAL) {
673	>	Throwable ex;
674	>	if (s == CANCELLED)
675	>	throw new CancellationException();
676	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
677	>	throw new ExecutionException(ex);
678	>	}
679		return getRawResult();
680		}
681
682		/**
683	<	* Performs this task, awaits its completion if necessary, and
684	<	* return its result.
685	<	* @throws Throwable (a RuntimeException, Error, or unchecked
686	<	* exception) if the underlying computation did so.
683	>	* Waits if necessary for at most the given time for the computation
684	>	* to complete, and then retrieves its result, if available.
685	>	*
686	>	* @param timeout the maximum time to wait
687	>	* @param unit the time unit of the timeout argument
688		* @return the computed result
689	+	* @throws CancellationException if the computation was cancelled
690	+	* @throws ExecutionException if the computation threw an
691	+	* exception
692	+	* @throws InterruptedException if the current thread is not a
693	+	* member of a ForkJoinPool and was interrupted while waiting
694	+	* @throws TimeoutException if the wait timed out
695		*/
696	<	public final V invoke() {
697	<	if (status >= 0 && tryExec())
698	<	return getRawResult();
696	>	public final V get(long timeout, TimeUnit unit)
697	>	throws InterruptedException, ExecutionException, TimeoutException {
698	>	Thread t = Thread.currentThread();
699	>	ForkJoinPool pool;
700	>	if (t instanceof ForkJoinWorkerThread) {
701	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
702	>	if (status >= 0 && w.unpushTask(this))
703	>	quietlyExec();
704	>	pool = w.pool;
705	>	}
706		else
707	<	return join();
707	>	pool = null;
708	>	/*
709	>	* Timed wait loop intermixes cases for FJ (pool != null) and
710	>	* non FJ threads. For FJ, decrement pool count but don't try
711	>	* for replacement; increment count on completion. For non-FJ,
712	>	* deal with interrupts. This is messy, but a little less so
713	>	* than is splitting the FJ and nonFJ cases.
714	>	*/
715	>	boolean interrupted = false;
716	>	boolean dec = false; // true if pool count decremented
717	>	long nanos = unit.toNanos(timeout);
718	>	for (;;) {
719	>	if (pool == null && Thread.interrupted()) {
720	>	interrupted = true;
721	>	break;
722	>	}
723	>	int s = status;
724	>	if (s < 0)
725	>	break;
726	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
727	>	long startTime = System.nanoTime();
728	>	long nt; // wait time
729	>	while (status >= 0 &&
730	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
731	>	if (pool != null && !dec)
732	>	dec = pool.tryDecrementRunningCount();
733	>	else {
734	>	long ms = nt / 1000000;
735	>	int ns = (int) (nt % 1000000);
736	>	try {
737	>	synchronized (this) {
738	>	if (status >= 0)
739	>	wait(ms, ns);
740	>	}
741	>	} catch (InterruptedException ie) {
742	>	if (pool != null)
743	>	cancelIfTerminating();
744	>	else {
745	>	interrupted = true;
746	>	break;
747	>	}
748	>	}
749	>	}
750	>	}
751	>	break;
752	>	}
753	>	}
754	>	if (pool != null && dec)
755	>	pool.incrementRunningCount();
756	>	if (interrupted)
757	>	throw new InterruptedException();
758	>	int es = status;
759	>	if (es != NORMAL) {
760	>	Throwable ex;
761	>	if (es == CANCELLED)
762	>	throw new CancellationException();
763	>	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
764	>	throw new ExecutionException(ex);
765	>	throw new TimeoutException();
766	>	}
767	>	return getRawResult();
768		}
769
770		/**
771	<	* Joins this task, without returning its result or throwing an
771	>	* Joins this task, without returning its result or throwing its
772		* exception. This method may be useful when processing
773		* collections of tasks when some have been cancelled or otherwise
774		* known to have aborted.
775		*/
776		public final void quietlyJoin() {
777	<	if (status >= 0) {
778	<	ForkJoinWorkerThread w = getWorker();
779	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
780	<	awaitDone(w, true);
777	>	Thread t;
778	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
779	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
780	>	if (status >= 0) {
781	>	if (w.unpushTask(this)) {
782	>	boolean completed;
783	>	try {
784	>	completed = exec();
785	>	} catch (Throwable rex) {
786	>	setExceptionalCompletion(rex);
787	>	return;
788	>	}
789	>	if (completed) {
790	>	setCompletion(NORMAL);
791	>	return;
792	>	}
793	>	}
794	>	w.joinTask(this);
795	>	}
796		}
797	+	else
798	+	externalAwaitDone();
799		}
800
801		/**
802	<	* Possibly executes other tasks until this task is ready.
802	>	* Commences performing this task and awaits its completion if
803	>	* necessary, without returning its result or throwing its
804	>	* exception.
805		*/
806	<	public final void quietlyHelpJoin() {
806	>	public final void quietlyInvoke() {
807		if (status >= 0) {
808	<	ForkJoinWorkerThread w =
809	<	(ForkJoinWorkerThread)(Thread.currentThread());
810	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
811	<	w.helpJoinTask(this);
808	>	boolean completed;
809	>	try {
810	>	completed = exec();
811	>	} catch (Throwable rex) {
812	>	setExceptionalCompletion(rex);
813	>	return;
814	>	}
815	>	if (completed)
816	>	setCompletion(NORMAL);
817	>	else
818	>	quietlyJoin();
819		}
820		}
821
822		/**
823	<	* Performs this task and awaits its completion if necessary,
824	<	* without returning its result or throwing an exception. This
825	<	* method may be useful when processing collections of tasks when
826	<	* some have been cancelled or otherwise known to have aborted.
823	>	* Possibly executes tasks until the pool hosting the current task
824	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
825	>	* be of use in designs in which many tasks are forked, but none
826	>	* are explicitly joined, instead executing them until all are
827	>	* processed.
828	>	*
829	>	* <p>This method may be invoked only from within {@code
830	>	* ForkJoinTask} computations (as may be determined using method
831	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
832	>	* result in exceptions or errors, possibly including {@code
833	>	* ClassCastException}.
834		*/
835	<	public final void quietlyInvoke() {
836	<	if (status >= 0 && !tryQuietlyInvoke())
837	<	quietlyJoin();
835	>	public static void helpQuiesce() {
836	>	((ForkJoinWorkerThread) Thread.currentThread())
837	>	.helpQuiescePool();
838		}
839
840		/**
841	<	* Returns true if the computation performed by this task has
842	<	* completed (or has been cancelled).
843	<	* @return true if this computation has completed
841	>	* Resets the internal bookkeeping state of this task, allowing a
842	>	* subsequent {@code fork}. This method allows repeated reuse of
843	>	* this task, but only if reuse occurs when this task has either
844	>	* never been forked, or has been forked, then completed and all
845	>	* outstanding joins of this task have also completed. Effects
846	>	* under any other usage conditions are not guaranteed.
847	>	* This method may be useful when executing
848	>	* pre-constructed trees of subtasks in loops.
849		*/
850	<	public final boolean isDone() {
851	<	return status < 0;
850	>	public void reinitialize() {
851	>	if (status == EXCEPTIONAL)
852	>	exceptionMap.remove(this);
853	>	status = 0;
854		}
855
856		/**
857	<	* Returns true if this task was cancelled.
858	<	* @return true if this task was cancelled
857	>	* Returns the pool hosting the current task execution, or null
858	>	* if this task is executing outside of any ForkJoinPool.
859	>	*
860	>	* @see #inForkJoinPool
861	>	* @return the pool, or {@code null} if none
862		*/
863	<	public final boolean isCancelled() {
864	<	return (status & COMPLETION_MASK) == CANCELLED;
863	>	public static ForkJoinPool getPool() {
864	>	Thread t = Thread.currentThread();
865	>	return (t instanceof ForkJoinWorkerThread) ?
866	>	((ForkJoinWorkerThread) t).pool : null;
867		}
868
869		/**
870	<	* Returns true if this task threw an exception or was cancelled
871	<	* @return true if this task threw an exception or was cancelled
870	>	* Returns {@code true} if the current thread is executing as a
871	>	* ForkJoinPool computation.
872	>	*
873	>	* @return {@code true} if the current thread is executing as a
874	>	* ForkJoinPool computation, or false otherwise
875		*/
876	<	public final boolean completedAbnormally() {
877	<	return (status & COMPLETION_MASK) < NORMAL;
876	>	public static boolean inForkJoinPool() {
877	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
878		}
879
880		/**
881	<	* Returns the exception thrown by the base computation, or a
882	<	* CancellationException if cancelled, or null if none or if the
883	<	* method has not yet completed.
884	<	* @return the exception, or null if none
881	>	* Tries to unschedule this task for execution. This method will
882	>	* typically succeed if this task is the most recently forked task
883	>	* by the current thread, and has not commenced executing in
884	>	* another thread.  This method may be useful when arranging
885	>	* alternative local processing of tasks that could have been, but
886	>	* were not, stolen.
887	>	*
888	>	* <p>This method may be invoked only from within {@code
889	>	* ForkJoinTask} computations (as may be determined using method
890	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
891	>	* result in exceptions or errors, possibly including {@code
892	>	* ClassCastException}.
893	>	*
894	>	* @return {@code true} if unforked
895		*/
896	<	public final Throwable getException() {
897	<	int s = status & COMPLETION_MASK;
898	<	if (s >= NORMAL)
600	<	return null;
601	<	if (s == CANCELLED)
602	<	return new CancellationException();
603	<	return exceptionMap.get(this);
896	>	public boolean tryUnfork() {
897	>	return ((ForkJoinWorkerThread) Thread.currentThread())
898	>	.unpushTask(this);
899		}
900
901		/**
902	<	* Asserts that the results of this task's computation will not be
903	<	* used. If a cancellation occurs before this task is processed,
904	<	* then its <tt>compute</tt> method will not be executed,
905	<	* <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.
902	>	* Returns an estimate of the number of tasks that have been
903	>	* forked by the current worker thread but not yet executed. This
904	>	* value may be useful for heuristic decisions about whether to
905	>	* fork other tasks.
906		*
907	<	* <p>This method may be overridden in subclasses, but if so, must
908	<	* still ensure that these minimal properties hold. In particular,
909	<	* the cancel method itself must not throw exceptions.
907	>	* <p>This method may be invoked only from within {@code
908	>	* ForkJoinTask} computations (as may be determined using method
909	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
910	>	* result in exceptions or errors, possibly including {@code
911	>	* ClassCastException}.
912		*
913	<	* <p> This method is designed to be invoked by <em>other</em>
914	<	* tasks. To terminate the current task, you can just return or
915	<	* throw an unchecked exception from its computation method, or
916	<	* invoke <tt>completeExceptionally(someException)</tt>.
913	>	* @return the number of tasks
914	>	*/
915	>	public static int getQueuedTaskCount() {
916	>	return ((ForkJoinWorkerThread) Thread.currentThread())
917	>	.getQueueSize();
918	>	}
919	>
920	>	/**
921	>	* Returns an estimate of how many more locally queued tasks are
922	>	* held by the current worker thread than there are other worker
923	>	* threads that might steal them.  This value may be useful for
924	>	* heuristic decisions about whether to fork other tasks. In many
925	>	* usages of ForkJoinTasks, at steady state, each worker should
926	>	* aim to maintain a small constant surplus (for example, 3) of
927	>	* tasks, and to process computations locally if this threshold is
928	>	* exceeded.
929		*
930	<	* @param mayInterruptIfRunning this value is ignored in the
931	<	* default implementation because tasks are not in general
932	<	* cancelled via interruption.
930	>	* <p>This method may be invoked only from within {@code
931	>	* ForkJoinTask} computations (as may be determined using method
932	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
933	>	* result in exceptions or errors, possibly including {@code
934	>	* ClassCastException}.
935		*
936	<	* @return true if this task is now cancelled
936	>	* @return the surplus number of tasks, which may be negative
937		*/
938	<	public boolean cancel(boolean mayInterruptIfRunning) {
939	<	setCompletion(CANCELLED);
940	<	return (status & COMPLETION_MASK) == CANCELLED;
938	>	public static int getSurplusQueuedTaskCount() {
939	>	return ((ForkJoinWorkerThread) Thread.currentThread())
940	>	.getEstimatedSurplusTaskCount();
941		}
942
943	+	// Extension methods
944	+
945		/**
946	<	* Completes this task abnormally, and if not already aborted or
947	<	* cancelled, causes it to throw the given exception upon
948	<	* <tt>join</tt> and related operations. This method may be used
949	<	* to induce exceptions in asynchronous tasks, or to force
950	<	* completion of tasks that would not otherwise complete.  This
951	<	* method is overridable, but overridden versions must invoke
952	<	* <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.
946	>	* Returns the result that would be returned by {@link #join}, even
947	>	* if this task completed abnormally, or {@code null} if this task
948	>	* is not known to have been completed.  This method is designed
949	>	* to aid debugging, as well as to support extensions. Its use in
950	>	* any other context is discouraged.
951	>	*
952	>	* @return the result, or {@code null} if not completed
953		*/
954	<	public void completeExceptionally(Throwable ex) {
651	<	setDoneExceptionally((ex instanceof RuntimeException) ||
652	<	(ex instanceof Error)? ex :
653	<	new RuntimeException(ex));
654	<	}
954	>	public abstract V getRawResult();
955
956		/**
957	<	* Completes this task, and if not already aborted or cancelled,
958	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
959	<	* 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.
957	>	* Forces the given value to be returned as a result.  This method
958	>	* is designed to support extensions, and should not in general be
959	>	* called otherwise.
960		*
961	<	* @param value the result value for this task.
961	>	* @param value the value
962		*/
963	<	public void complete(V value) {
666	<	try {
667	<	setRawResult(value);
668	<	} catch(Throwable rex) {
669	<	setDoneExceptionally(rex);
670	<	return;
671	<	}
672	<	setNormalCompletion();
673	<	}
963	>	protected abstract void setRawResult(V value);
964
965		/**
966	<	* Resets the internal bookkeeping state of this task, allowing a
967	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
968	<	* this task, but only if reuse occurs when this task has either
969	<	* never been forked, or has been forked, then completed and all
970	<	* outstanding joins of this task have also completed. Effects
971	<	* under any other usage conditions are not guaranteed, and are
972	<	* almost surely wrong. This method may be useful when executing
973	<	* pre-constructed trees of subtasks in loops.
966	>	* Immediately performs the base action of this task.  This method
967	>	* is designed to support extensions, and should not in general be
968	>	* called otherwise. The return value controls whether this task
969	>	* is considered to be done normally. It may return false in
970	>	* asynchronous actions that require explicit invocations of
971	>	* {@link #complete} to become joinable. It may also throw an
972	>	* (unchecked) exception to indicate abnormal exit.
973	>	*
974	>	* @return {@code true} if completed normally
975		*/
976	<	public void reinitialize() {
686	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
687	<	exceptionMap.remove(this);
688	<	status = 0;
689	<	}
976	>	protected abstract boolean exec();
977
978		/**
979	<	* Tries to unschedule this task for execution. This method will
980	<	* typically succeed if this task is the next task that would be
981	<	* executed by the current thread, and will typically fail (return
982	<	* false) otherwise. This method may be useful when arranging
983	<	* faster local processing of tasks that could have been, but were
984	<	* not, stolen.
985	<	* @return true if unforked
979	>	* Returns, but does not unschedule or execute, a task queued by
980	>	* the current thread but not yet executed, if one is immediately
981	>	* available. There is no guarantee that this task will actually
982	>	* be polled or executed next. Conversely, this method may return
983	>	* null even if a task exists but cannot be accessed without
984	>	* contention with other threads.  This method is designed
985	>	* primarily to support extensions, and is unlikely to be useful
986	>	* otherwise.
987	>	*
988	>	* <p>This method may be invoked only from within {@code
989	>	* ForkJoinTask} computations (as may be determined using method
990	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
991	>	* result in exceptions or errors, possibly including {@code
992	>	* ClassCastException}.
993	>	*
994	>	* @return the next task, or {@code null} if none are available
995		*/
996	<	public boolean tryUnfork() {
997	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
996	>	protected static ForkJoinTask<?> peekNextLocalTask() {
997	>	return ((ForkJoinWorkerThread) Thread.currentThread())
998	>	.peekTask();
999		}
1000
1001		/**
1002	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
1003	<	* of them or an exception is encountered. This method may be
1004	<	* invoked only from within other ForkJoinTask
1005	<	* computations. Attempts to invoke in other contexts result in
1006	<	* exceptions or errors including ClassCastException.
1007	<	* @param t1 one task
1008	<	* @param t2 the other task
1009	<	* @throws NullPointerException if t1 or t2 are null
1010	<	* @throws RuntimeException or Error if either task did so.
1002	>	* Unschedules and returns, without executing, the next task
1003	>	* queued by the current thread but not yet executed.  This method
1004	>	* is designed primarily to support extensions, and is unlikely to
1005	>	* be useful otherwise.
1006	>	*
1007	>	* <p>This method may be invoked only from within {@code
1008	>	* ForkJoinTask} computations (as may be determined using method
1009	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1010	>	* result in exceptions or errors, possibly including {@code
1011	>	* ClassCastException}.
1012	>	*
1013	>	* @return the next task, or {@code null} if none are available
1014		*/
1015	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
1016	<	t2.fork();
1017	<	t1.invoke();
718	<	t2.join();
1015	>	protected static ForkJoinTask<?> pollNextLocalTask() {
1016	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1017	>	.pollLocalTask();
1018		}
1019
1020		/**
1021	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
1022	<	* all of them. If any task encounters an exception, others may be
1023	<	* cancelled.  This method may be invoked only from within other
1024	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1025	<	* result in exceptions or errors including ClassCastException.
1026	<	* @param tasks the array of tasks
1027	<	* @throws NullPointerException if tasks or any element are null.
1028	<	* @throws RuntimeException or Error if any task did so.
1021	>	* Unschedules and returns, without executing, the next task
1022	>	* queued by the current thread but not yet executed, if one is
1023	>	* available, or if not available, a task that was forked by some
1024	>	* other thread, if available. Availability may be transient, so a
1025	>	* {@code null} result does not necessarily imply quiescence
1026	>	* of the pool this task is operating in.  This method is designed
1027	>	* primarily to support extensions, and is unlikely to be useful
1028	>	* otherwise.
1029	>	*
1030	>	* <p>This method may be invoked only from within {@code
1031	>	* ForkJoinTask} computations (as may be determined using method
1032	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1033	>	* result in exceptions or errors, possibly including {@code
1034	>	* ClassCastException}.
1035	>	*
1036	>	* @return a task, or {@code null} if none are available
1037		*/
1038	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
1039	<	Throwable ex = null;
1040	<	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);
1038	>	protected static ForkJoinTask<?> pollTask() {
1039	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1040	>	.pollTask();
1041		}
1042
1043		/**
1044	<	* Forks all tasks in the collection, returning when
1045	<	* <tt>isDone</tt> holds for all of them. If any task encounters
1046	<	* 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.
1044	>	* Adaptor for Runnables. This implements RunnableFuture
1045	>	* to be compliant with AbstractExecutorService constraints
1046	>	* when used in ForkJoinPool.
1047		*/
1048	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
1049	<	if (!(tasks instanceof List)) {
1050	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
1051	<	return;
1052	<	}
1053	<	List<? extends ForkJoinTask<?>> ts =
1054	<	(List<? extends ForkJoinTask<?>>)tasks;
1055	<	Throwable ex = null;
1056	<	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	<	}
1048	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1049	>	implements RunnableFuture<T> {
1050	>	final Runnable runnable;
1051	>	final T resultOnCompletion;
1052	>	T result;
1053	>	AdaptedRunnable(Runnable runnable, T result) {
1054	>	if (runnable == null) throw new NullPointerException();
1055	>	this.runnable = runnable;
1056	>	this.resultOnCompletion = result;
1057		}
1058	<	for (int i = 1; i <= last; ++i) {
1059	<	ForkJoinTask<?> t = ts.get(i);
1060	<	if (t != null) {
1061	<	if (ex != null)
1062	<	t.cancel(false);
1063	<	else {
804	<	t.quietlyJoin();
805	<	if (ex == null)
806	<	ex = t.getException();
807	<	}
808	<	}
1058	>	public T getRawResult() { return result; }
1059	>	public void setRawResult(T v) { result = v; }
1060	>	public boolean exec() {
1061	>	runnable.run();
1062	>	result = resultOnCompletion;
1063	>	return true;
1064		}
1065	<	if (ex != null)
1066	<	rethrowException(ex);
1065	>	public void run() { invoke(); }
1066	>	private static final long serialVersionUID = 5232453952276885070L;
1067		}
1068
1069		/**
1070	<	* 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.
1070	>	* Adaptor for Callables
1071		*/
1072	<	public static void helpQuiesce() {
1073	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1074	<	helpQuiescePool();
1072	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1073	>	implements RunnableFuture<T> {
1074	>	final Callable<? extends T> callable;
1075	>	T result;
1076	>	AdaptedCallable(Callable<? extends T> callable) {
1077	>	if (callable == null) throw new NullPointerException();
1078	>	this.callable = callable;
1079	>	}
1080	>	public T getRawResult() { return result; }
1081	>	public void setRawResult(T v) { result = v; }
1082	>	public boolean exec() {
1083	>	try {
1084	>	result = callable.call();
1085	>	return true;
1086	>	} catch (Error err) {
1087	>	throw err;
1088	>	} catch (RuntimeException rex) {
1089	>	throw rex;
1090	>	} catch (Exception ex) {
1091	>	throw new RuntimeException(ex);
1092	>	}
1093	>	}
1094	>	public void run() { invoke(); }
1095	>	private static final long serialVersionUID = 2838392045355241008L;
1096		}
1097
1098		/**
1099	<	* Returns a estimate of how many more locally queued tasks are
1100	<	* held by the current worker thread than there are other worker
1101	<	* threads that might want to steal them.  This value may be
1102	<	* useful for heuristic decisions about whether to fork other
1103	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
1104	<	* 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
1099	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1100	>	* method of the given {@code Runnable} as its action, and returns
1101	>	* a null result upon {@link #join}.
1102	>	*
1103	>	* @param runnable the runnable action
1104	>	* @return the task
1105		*/
1106	<	public static int surplus() {
1107	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
838	<	.getEstimatedSurplusTaskCount();
1106	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1107	>	return new AdaptedRunnable<Void>(runnable, null);
1108		}
1109
841	–	// Extension kit
842	–
1110		/**
1111	<	* Returns the result that would be returned by <tt>join</tt>, or
1112	<	* null if this task is not known to have been completed.  This
1113	<	* method is designed to aid debugging, as well as to support
847	<	* extensions. Its use in any other context is discouraged.
1111	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1112	>	* method of the given {@code Runnable} as its action, and returns
1113	>	* the given result upon {@link #join}.
1114		*
1115	<	* @return the result, or null if not completed.
1115	>	* @param runnable the runnable action
1116	>	* @param result the result upon completion
1117	>	* @return the task
1118		*/
1119	<	public abstract V getRawResult();
1119	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1120	>	return new AdaptedRunnable<T>(runnable, result);
1121	>	}
1122
1123		/**
1124	<	* Forces the given value to be returned as a result.  This method
1125	<	* is designed to support extensions, and should not in general be
1126	<	* called otherwise.
1124	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1125	>	* method of the given {@code Callable} as its action, and returns
1126	>	* its result upon {@link #join}, translating any checked exceptions
1127	>	* encountered into {@code RuntimeException}.
1128		*
1129	<	* @param value the value
1130	<	*/
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
1129	>	* @param callable the callable action
1130	>	* @return the task
1131		*/
1132	<	protected abstract boolean exec();
1132	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1133	>	return new AdaptedCallable<T>(callable);
1134	>	}
1135
1136		// Serialization support
1137
1138		private static final long serialVersionUID = -7721805057305804111L;
1139
1140		/**
1141	<	* Save the state to a stream.
1141	>	* Saves the state to a stream (that is, serializes it).
1142		*
1143		* @serialData the current run status and the exception thrown
1144	<	* during execution, or null if none.
1144	>	* during execution, or {@code null} if none
1145		* @param s the stream
1146		*/
1147		private void writeObject(java.io.ObjectOutputStream s)
#	Line 890 | Line 1151 | public abstract class ForkJoinTask<V> im
1151		}
1152
1153		/**
1154	<	* Reconstitute the instance from a stream.
1154	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1155	>	*
1156		* @param s the stream
1157		*/
1158		private void readObject(java.io.ObjectInputStream s)
1159		throws java.io.IOException, ClassNotFoundException {
1160		s.defaultReadObject();
899	–	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1161		Object ex = s.readObject();
1162		if (ex != null)
1163	<	setDoneExceptionally((Throwable)ex);
1163	>	setExceptionalCompletion((Throwable) ex);
1164		}
1165
1166	<	// Temporary Unsafe mechanics for preliminary release
1166	>	// Unsafe mechanics
1167
1168	<	static final Unsafe _unsafe;
1169	<	static final long statusOffset;
1168	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1169	>	private static final long statusOffset =
1170	>	objectFieldOffset("status", ForkJoinTask.class);
1171
1172	<	static {
1172	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1173		try {
1174	<	if (ForkJoinTask.class.getClassLoader() != null) {
1175	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1176	<	f.setAccessible(true);
1177	<	_unsafe = (Unsafe)f.get(null);
1178	<	}
1179	<	else
1180	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
920	<	(ForkJoinTask.class.getDeclaredField("status"));
921	<	} catch (Exception ex) { throw new Error(ex); }
1174	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1175	>	} catch (NoSuchFieldException e) {
1176	>	// Convert Exception to corresponding Error
1177	>	NoSuchFieldError error = new NoSuchFieldError(field);
1178	>	error.initCause(e);
1179	>	throw error;
1180	>	}
1181		}
1182
1183	+	/**
1184	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1185	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1186	+	* into a jdk.
1187	+	*
1188	+	* @return a sun.misc.Unsafe
1189	+	*/
1190	+	private static sun.misc.Unsafe getUnsafe() {
1191	+	try {
1192	+	return sun.misc.Unsafe.getUnsafe();
1193	+	} catch (SecurityException se) {
1194	+	try {
1195	+	return java.security.AccessController.doPrivileged
1196	+	(new java.security
1197	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1198	+	public sun.misc.Unsafe run() throws Exception {
1199	+	java.lang.reflect.Field f = sun.misc
1200	+	.Unsafe.class.getDeclaredField("theUnsafe");
1201	+	f.setAccessible(true);
1202	+	return (sun.misc.Unsafe) f.get(null);
1203	+	}});
1204	+	} catch (java.security.PrivilegedActionException e) {
1205	+	throw new RuntimeException("Could not initialize intrinsics",
1206	+	e.getCause());
1207	+	}
1208	+	}
1209	+	}
1210		}

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