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Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.1 by dl, Tue Jan 6 14:30:31 2009 UTC vs.
Revision 1.48 by dl, Thu May 27 16:46:48 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	>
11	>	import java.io.Serializable;
12	>	import java.util.Collection;
13	>	import java.util.Collections;
14	>	import java.util.List;
15	>	import java.util.RandomAccess;
16	>	import java.util.Map;
17	>	import java.util.WeakHashMap;
18
19		/**
20	<	* Abstract base class for tasks that run within a ForkJoinPool.  A
21	<	* ForkJoinTask is a thread-like entity that is much lighter weight
22	<	* than a normal thread.  Huge numbers of tasks and subtasks may be
23	<	* hosted by a small number of actual threads in a ForkJoinPool,
24	<	* at the price of some usage limitations.
20	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
21	>	* A {@code ForkJoinTask} is a thread-like entity that is much
22	>	* lighter weight than a normal thread.  Huge numbers of tasks and
23	>	* subtasks may be hosted by a small number of actual threads in a
24	>	* ForkJoinPool, at the price of some usage limitations.
25		*
26	<	* <p> ForkJoinTasks are forms of <tt>Futures</tt> supporting a
27	<	* limited range of use.  The "lightness" of ForkJoinTasks is due to a
28	<	* set of restrictions (that are only partially statically
29	<	* enforceable) reflecting their intended use as computational tasks
30	<	* calculating pure functions or operating on purely isolated objects.
31	<	* The primary coordination mechanisms supported for ForkJoinTasks are
32	<	* <tt>fork</tt>, that arranges asynchronous execution, and
33	<	* <tt>join</tt>, that doesn't proceed until the task's result has
34	<	* been computed. (Cancellation is also supported).  The computation
31	<	* defined in the <tt>compute</tt> method should avoid
32	<	* <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.
26	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
27	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
28	>	* start other subtasks.  As indicated by the name of this class,
29	>	* many programs using {@code ForkJoinTask} employ only methods
30	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
31	>	* #invokeAll}.  However, this class also provides a number of other
32	>	* methods that can come into play in advanced usages, as well as
33	>	* extension mechanics that allow support of new forms of fork/join
34	>	* processing.
35		*
36	<	* <p> The <tt>ForkJoinTask</tt> class is not usually directly
37	<	* subclassed.  Instead, you subclass one of the abstract classes that
38	<	* support different styles of fork/join processing.  Normally, a
39	<	* concrete ForkJoinTask subclass declares fields comprising its
40	<	* parameters, established in a constructor, and then defines a
41	<	* <tt>compute</tt> method that somehow uses the control methods
42	<	* supplied by this base class. While these methods have
43	<	* <tt>public</tt> access, some of them may only be called from within
44	<	* other ForkJoinTasks. Attempts to invoke them in other contexts
45	<	* result in exceptions or errors including ClassCastException.  The
46	<	* only way to invoke a "main" driver task is to submit it to a
47	<	* ForkJoinPool. Once started, this will usually in turn start other
48	<	* subtasks.
36	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
37	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
38	>	* restrictions (that are only partially statically enforceable)
39	>	* reflecting their intended use as computational tasks calculating
40	>	* pure functions or operating on purely isolated objects.  The
41	>	* primary coordination mechanisms are {@link #fork}, that arranges
42	>	* asynchronous execution, and {@link #join}, that doesn't proceed
43	>	* until the task's result has been computed.  Computations should
44	>	* avoid {@code synchronized} methods or blocks, and should minimize
45	>	* other blocking synchronization apart from joining other tasks or
46	>	* using synchronizers such as Phasers that are advertised to
47	>	* cooperate with fork/join scheduling. Tasks should also not perform
48	>	* blocking IO, and should ideally access variables that are
49	>	* completely independent of those accessed by other running
50	>	* tasks. Minor breaches of these restrictions, for example using
51	>	* shared output streams, may be tolerable in practice, but frequent
52	>	* use may result in poor performance, and the potential to
53	>	* indefinitely stall if the number of threads not waiting for IO or
54	>	* other external synchronization becomes exhausted. This usage
55	>	* restriction is in part enforced by not permitting checked
56	>	* exceptions such as {@code IOExceptions} to be thrown. However,
57	>	* computations may still encounter unchecked exceptions, that are
58	>	* rethrown to callers attempting to join them. These exceptions may
59	>	* additionally include {@link RejectedExecutionException} stemming
60	>	* from internal resource exhaustion, such as failure to allocate
61	>	* internal task queues.
62		*
63	<	* <p>Most base support methods are <tt>final</tt> because their
64	<	* implementations are intrinsically tied to the underlying
65	<	* lightweight task scheduling framework, and so cannot be overridden.
66	<	* Developers creating new basic styles of fork/join processing should
67	<	* minimally implement protected methods <tt>exec</tt>,
68	<	* <tt>setRawResult</tt>, and <tt>getRawResult</tt>, while also
69	<	* introducing an abstract computational method that can be
70	<	* implemented in its subclasses. To support such extensions,
71	<	* instances of ForkJoinTasks maintain an atomically updated
72	<	* <tt>short</tt> representing user-defined control state.  Control
73	<	* state is guaranteed initially to be zero, and to be negative upon
74	<	* completion, but may otherwise be used for any other control
75	<	* purposes, such as maintaining join counts.  The {@link
76	<	* ForkJoinWorkerThread} class supports additional inspection and
77	<	* tuning methods that can be useful when developing extensions.
63	>	* <p>The primary method for awaiting completion and extracting
64	>	* results of a task is {@link #join}, but there are several variants:
65	>	* The {@link Future#get} methods support interruptible and/or timed
66	>	* waits for completion and report results using {@code Future}
67	>	* conventions. Method {@link #helpJoin} enables callers to actively
68	>	* execute other tasks while awaiting joins, which is sometimes more
69	>	* efficient but only applies when all subtasks are known to be
70	>	* strictly tree-structured. Method {@link #invoke} is semantically
71	>	* equivalent to {@code fork(); join()} but always attempts to begin
72	>	* execution in the current thread. The "<em>quiet</em>" forms of
73	>	* these methods do not extract results or report exceptions. These
74	>	* may be useful when a set of tasks are being executed, and you need
75	>	* to delay processing of results or exceptions until all complete.
76	>	* Method {@code invokeAll} (available in multiple versions)
77	>	* performs the most common form of parallel invocation: forking a set
78	>	* of tasks and joining them all.
79	>	*
80	>	* <p>The execution status of tasks may be queried at several levels
81	>	* of detail: {@link #isDone} is true if a task completed in any way
82	>	* (including the case where a task was cancelled without executing);
83	>	* {@link #isCompletedNormally} is true if a task completed without
84	>	* cancellation or encountering an exception; {@link #isCancelled} is
85	>	* true if the task was cancelled (in which case {@link #getException}
86	>	* returns a {@link java.util.concurrent.CancellationException}); and
87	>	* {@link #isCompletedAbnormally} is true if a task was either
88	>	* cancelled or encountered an exception, in which case {@link
89	>	* #getException} will return either the encountered exception or
90	>	* {@link java.util.concurrent.CancellationException}.
91	>	*
92	>	* <p>The ForkJoinTask class is not usually directly subclassed.
93	>	* Instead, you subclass one of the abstract classes that support a
94	>	* particular style of fork/join processing, typically {@link
95	>	* RecursiveAction} for computations that do not return results, or
96	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
97	>	* ForkJoinTask subclass declares fields comprising its parameters,
98	>	* established in a constructor, and then defines a {@code compute}
99	>	* method that somehow uses the control methods supplied by this base
100	>	* class. While these methods have {@code public} access (to allow
101	>	* instances of different task subclasses to call each other's
102	>	* methods), some of them may only be called from within other
103	>	* ForkJoinTasks (as may be determined using method {@link
104	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
105	>	* result in exceptions or errors, possibly including
106	>	* ClassCastException.
107	>	*
108	>	* <p>Most base support methods are {@code final}, to prevent
109	>	* overriding of implementations that are intrinsically tied to the
110	>	* underlying lightweight task scheduling framework.  Developers
111	>	* creating new basic styles of fork/join processing should minimally
112	>	* implement {@code protected} methods {@link #exec}, {@link
113	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
114	>	* an abstract computational method that can be implemented in its
115	>	* subclasses, possibly relying on other {@code protected} methods
116	>	* provided by this class.
117		*
118		* <p>ForkJoinTasks should perform relatively small amounts of
119	<	* computations, othewise splitting into smaller tasks. As a very
120	<	* rough rule of thumb, a task should perform more than 100 and less
121	<	* than 10000 basic computational steps. If tasks are too big, then
122	<	* parellelism cannot improve throughput. If too small, then memory
123	<	* and internal task maintenance overhead may overwhelm processing.
119	>	* computation. Large tasks should be split into smaller subtasks,
120	>	* usually via recursive decomposition. As a very rough rule of thumb,
121	>	* a task should perform more than 100 and less than 10000 basic
122	>	* computational steps. If tasks are too big, then parallelism cannot
123	>	* improve throughput. If too small, then memory and internal task
124	>	* maintenance overhead may overwhelm processing.
125	>	*
126	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
127	>	* and {@link Callable}, that may be of use when mixing execution of
128	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
129	>	* are of this form, consider using a pool in
130	>	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
131		*
132	<	* <p>ForkJoinTasks are <tt>Serializable</tt>, which enables them to
133	<	* be used in extensions such as remote execution frameworks. However,
134	<	* it is in general safe to serialize tasks only before or after, but
135	<	* not during execution. Serialization is not relied on during
136	<	* execution itself.
132	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
133	>	* used in extensions such as remote execution frameworks. It is
134	>	* sensible to serialize tasks only before or after, but not during,
135	>	* execution. Serialization is not relied on during execution itself.
136	>	*
137	>	* @since 1.7
138	>	* @author Doug Lea
139		*/
140		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
141	+
142	+	/*
143	+	* See the internal documentation of class ForkJoinPool for a
144	+	* general implementation overview.  ForkJoinTasks are mainly
145	+	* responsible for maintaining their "status" field amidst relays
146	+	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
147	+	* methods of this class are more-or-less layered into (1) basic
148	+	* status maintenance (2) execution and awaiting completion (3)
149	+	* user-level methods that additionally report results. This is
150	+	* sometimes hard to see because this file orders exported methods
151	+	* in a way that flows well in javadocs.
152	+	*/
153	+
154		/**
155	<	* Status field holding all run status. We pack this into a single
156	<	* int both to minimize footprint overhead and to ensure atomicity
157	<	* (updates are via CAS).
98	<	*
99	<	* Status is initially zero, and takes on nonnegative values until
155	>	* Run control status bits packed into a single int to minimize
156	>	* footprint and to ensure atomicity (via CAS).  Status is
157	>	* initially zero, and takes on nonnegative values until
158		* completed, upon which status holds COMPLETED. CANCELLED, or
159		* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
160	<	* blocking waits by other threads have SIGNAL_MASK bits set --
161	<	* bit 15 for external (nonFJ) waits, and the rest a count of
162	<	* waiting FJ threads.  (This representation relies on
163	<	* ForkJoinPool max thread limits). Completion of a stolen task
164	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
165	<	* though suboptimal for some purposes, we use basic builtin
166	<	* wait/notify to take advantage of "monitor inflation" in JVMs
167	<	* that we would otherwise need to emulate to avoid adding further
168	<	* per-task bookkeeping overhead. Note that bits 16-28 are
169	<	* currently unused. Also value 0x80000000 is available as spare
170	<	* completion value.
171	<	*/
172	<	volatile int status; // accessed directy by pool and workers
173	<
174	<	static final int COMPLETION_MASK      = 0xe0000000;
175	<	static final int NORMAL               = 0xe0000000; // == mask
176	<	static final int CANCELLED            = 0xc0000000;
177	<	static final int EXCEPTIONAL          = 0xa0000000;
178	<	static final int SIGNAL_MASK          = 0x0000ffff;
179	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
180	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
160	>	* blocking waits by other threads have the SIGNAL bit set.
161	>	*
162	>	* Completion of a stolen task with SIGNAL set awakens any waiters
163	>	* via notifyAll. Even though suboptimal for some purposes, we use
164	>	* basic builtin wait/notify to take advantage of "monitor
165	>	* inflation" in JVMs that we would otherwise need to emulate to
166	>	* avoid adding further per-task bookkeeping overhead.  We want
167	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
168	>	* techniques, so use some odd coding idioms that tend to avoid
169	>	* them.
170	>	*
171	>	* Note that bits 1-28 are currently unused. Also value
172	>	* 0x80000000 is available as spare completion value.
173	>	*/
174	>	volatile int status; // accessed directly by pool and workers
175	>
176	>	private static final int COMPLETION_MASK      = 0xe0000000;
177	>	private static final int NORMAL               = 0xe0000000; // == mask
178	>	private static final int CANCELLED            = 0xc0000000;
179	>	private static final int EXCEPTIONAL          = 0xa0000000;
180	>	private static final int SIGNAL               = 0x00000001;
181
182		/**
183		* Table of exceptions thrown by tasks, to enable reporting by
184		* callers. Because exceptions are rare, we don't directly keep
185	<	* them with task objects, but instead us a weak ref table.  Note
185	>	* them with task objects, but instead use a weak ref table.  Note
186		* that cancellation exceptions don't appear in the table, but are
187		* instead recorded as status values.
188	<	* Todo: Use ConcurrentReferenceHashMap
188	>	* TODO: Use ConcurrentReferenceHashMap
189		*/
190		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
191		Collections.synchronizedMap
192		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
193
194	<	// within-package utilities
194	>	// Maintaining completion status
195
196		/**
197	<	* Get current worker thread, or null if not a worker thread
197	>	* Marks completion and wakes up threads waiting to join this task,
198	>	* also clearing signal request bits.
199	>	*
200	>	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
201	>	* @return status on exit
202		*/
203	<	static ForkJoinWorkerThread getWorker() {
204	<	Thread t = Thread.currentThread();
205	<	return ((t instanceof ForkJoinWorkerThread)?
206	<	(ForkJoinWorkerThread)t : null);
203	>	private int setCompletion(int completion) {
204	>	int s;
205	>	while ((s = status) >= 0) {
206	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
207	>	if ((s & SIGNAL) != 0)
208	>	synchronized (this) { notifyAll(); }
209	>	return completion;
210	>	}
211	>	}
212	>	return s;
213		}
214
215		/**
216	<	* Get pool of current worker thread, or null if not a worker thread
216	>	* Record exception and set exceptional completion
217	>	* @return status on exit
218		*/
219	<	static ForkJoinPool getWorkerPool() {
220	<	Thread t = Thread.currentThread();
221	<	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);
219	>	private int setExceptionalCompletion(Throwable rex) {
220	>	exceptionMap.put(this, rex);
221	>	return setCompletion(EXCEPTIONAL);
222		}
223
224		/**
225	<	* Workaround for not being able to rethrow unchecked exceptions.
225	>	* Blocks a worker thread until completion. Called only by pool.
226		*/
227	<	static void rethrowException(Throwable ex) {
228	<	if (ex != null)
229	<	_unsafe.throwException(ex);
227	>	final void internalAwaitDone() {
228	>	int s;
229	>	while ((s = status) >= 0) {
230	>	synchronized(this) {
231	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){
232	>	do {
233	>	try {
234	>	wait();
235	>	} catch (InterruptedException ie) {
236	>	cancelIfTerminating();
237	>	}
238	>	} while (status >= 0);
239	>	break;
240	>	}
241	>	}
242	>	}
243		}
244
168	–	// Setting completion status
169	–
245		/**
246	<	* Mark completion and wake up threads waiting to join this task.
247	<	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
246	>	* Blocks a non-worker-thread until completion.
247	>	* @return status on exit
248		*/
249	<	final void setCompletion(int completion) {
250	<	ForkJoinPool pool = getWorkerPool();
251	<	if (pool != null) {
252	<	int s; // Clear signal bits while setting completion status
253	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
254	<
255	<	if ((s & SIGNAL_MASK) != 0) {
256	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
257	<	pool.updateRunningCount(s);
258	<	synchronized(this) { notifyAll(); }
249	>	private int externalAwaitDone() {
250	>	int s;
251	>	while ((s = status) >= 0) {
252	>	synchronized(this) {
253	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){
254	>	boolean interrupted = false;
255	>	do {
256	>	try {
257	>	wait();
258	>	} catch (InterruptedException ie) {
259	>	interrupted = true;
260	>	}
261	>	} while ((s = status) >= 0);
262	>	if (interrupted)
263	>	Thread.currentThread().interrupt();
264	>	break;
265	>	}
266		}
267		}
268	<	else
187	<	externallySetCompletion(completion);
268	>	return s;
269		}
270
271		/**
272	<	* Version of setCompletion for non-FJ threads.  Leaves signal
273	<	* bits for unblocked threads to adjust, and always notifies.
272	>	* Unless done, calls exec and records status if completed, but
273	>	* doesn't wait for completion otherwise.
274		*/
275	<	private void externallySetCompletion(int completion) {
276	<	int s;
277	<	do;while ((s = status) >= 0 &&
278	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
279	<	synchronized(this) { notifyAll(); }
275	>	final void tryExec() {
276	>	try {
277	>	if (status < 0 || !exec())
278	>	return;
279	>	} catch (Throwable rex) {
280	>	setExceptionalCompletion(rex);
281	>	return;
282	>	}
283	>	setCompletion(NORMAL); // must be outside try block
284		}
285
286		/**
287	<	* Sets status to indicate normal completion
287	>	* If not done and this task is next in worker queue, runs it,
288	>	* else waits for it.
289	>	* @return status on exit
290		*/
291	<	final void setNormalCompletion() {
292	<	// Try typical fast case -- single CAS, no signal, not already done.
293	<	// Manually expand casStatus to improve chances of inlining it
294	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
295	<	setCompletion(NORMAL);
291	>	private int waitingJoin() {
292	>	int s = status;
293	>	if (s < 0)
294	>	return s;
295	>	Thread t = Thread.currentThread();
296	>	if (t instanceof ForkJoinWorkerThread) {
297	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
298	>	if (w.unpushTask(this)) {
299	>	boolean completed;
300	>	try {
301	>	completed = exec();
302	>	} catch (Throwable rex) {
303	>	return setExceptionalCompletion(rex);
304	>	}
305	>	if (completed)
306	>	return setCompletion(NORMAL);
307	>	}
308	>	return w.pool.awaitJoin(this);
309	>	}
310	>	else
311	>	return externalAwaitDone();
312		}
313
211	–	// internal waiting and notification
212	–
314		/**
315	<	* Performs the actual monitor wait for awaitDone
315	>	* Unless done, calls exec and records status if completed, or
316	>	* waits for completion otherwise.
317	>	* @return status on exit
318		*/
319	<	private void doAwaitDone() {
320	<	// Minimize lock bias and in/de-flation effects by maximizing
321	<	// chances of waiting inside sync
319	>	private int waitingInvoke() {
320	>	int s = status;
321	>	if (s < 0)
322	>	return s;
323	>	boolean completed;
324		try {
325	<	while (status >= 0)
326	<	synchronized(this) { if (status >= 0) wait(); }
327	<	} catch (InterruptedException ie) {
223	<	onInterruptedWait();
325	>	completed = exec();
326	>	} catch (Throwable rex) {
327	>	return setExceptionalCompletion(rex);
328		}
329	+	if (completed)
330	+	return setCompletion(NORMAL);
331	+	return waitingJoin();
332		}
333
334		/**
335	<	* Performs the actual monitor wait for awaitDone
335	>	* If this task is next in worker queue, runs it, else processes other
336	>	* tasks until complete.
337	>	* @return status on exit
338		*/
339	<	private void doAwaitDone(long startTime, long nanos) {
340	<	synchronized(this) {
339	>	private int busyJoin() {
340	>	int s = status;
341	>	if (s < 0)
342	>	return s;
343	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
344	>	if (w.unpushTask(this)) {
345	>	boolean completed;
346		try {
347	<	while (status >= 0) {
348	<	long nt = nanos - System.nanoTime() - startTime;
349	<	if (nt <= 0)
236	<	break;
237	<	wait(nt / 1000000, (int)(nt % 1000000));
238	<	}
239	<	} catch (InterruptedException ie) {
240	<	onInterruptedWait();
347	>	completed = exec();
348	>	} catch (Throwable rex) {
349	>	return setExceptionalCompletion(rex);
350		}
351	+	if (completed)
352	+	return setCompletion(NORMAL);
353		}
354	+	return w.execWhileJoining(this);
355		}
356
245	–	// Awaiting completion
246	–
357		/**
358	<	* Sets status to indicate there is joiner, then waits for join,
359	<	* surrounded with pool notifications.
250	<	* @return status upon exit
358	>	* Returns result or throws exception associated with given status.
359	>	* @param s the status
360		*/
361	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
362	<	ForkJoinPool pool = w == null? null : w.pool;
363	<	int s;
364	<	while ((s = status) >= 0) {
365	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
257	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
258	<	doAwaitDone();
259	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
260	<	adjustPoolCountsOnUnblock(pool);
261	<	break;
262	<	}
263	<	}
264	<	return s;
361	>	private V reportResult(int s) {
362	>	Throwable ex;
363	>	if (s < NORMAL && (ex = getException()) != null)
364	>	UNSAFE.throwException(ex);
365	>	return getRawResult();
366		}
367
368	+	// public methods
369	+
370		/**
371	<	* Timed version of awaitDone
372	<	* @return status upon exit
371	>	* Arranges to asynchronously execute this task.  While it is not
372	>	* necessarily enforced, it is a usage error to fork a task more
373	>	* than once unless it has completed and been reinitialized.
374	>	* Subsequent modifications to the state of this task or any data
375	>	* it operates on are not necessarily consistently observable by
376	>	* any thread other than the one executing it unless preceded by a
377	>	* call to {@link #join} or related methods, or a call to {@link
378	>	* #isDone} returning {@code true}.
379	>	*
380	>	* <p>This method may be invoked only from within {@code
381	>	* ForkJoinTask} computations (as may be determined using method
382	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
383	>	* result in exceptions or errors, possibly including {@code
384	>	* ClassCastException}.
385	>	*
386	>	* @return {@code this}, to simplify usage
387		*/
388	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
389	<	ForkJoinPool pool = w == null? null : w.pool;
390	<	int s;
391	<	while ((s = status) >= 0) {
275	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
276	<	long startTime = System.nanoTime();
277	<	if (pool == null || !pool.preJoin(this, false))
278	<	doAwaitDone(startTime, nanos);
279	<	if ((s = status) >= 0) {
280	<	adjustPoolCountsOnCancelledWait(pool);
281	<	s = status;
282	<	}
283	<	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
284	<	adjustPoolCountsOnUnblock(pool);
285	<	break;
286	<	}
287	<	}
288	<	return s;
388	>	public final ForkJoinTask<V> fork() {
389	>	((ForkJoinWorkerThread) Thread.currentThread())
390	>	.pushTask(this);
391	>	return this;
392		}
393
394		/**
395	<	* Notify pool that thread is unblocked. Called by signalled
396	<	* threads when woken by non-FJ threads (which is atypical).
395	>	* Returns the result of the computation when it {@link #isDone is done}.
396	>	* This method differs from {@link #get()} in that
397	>	* abnormal completion results in {@code RuntimeException} or
398	>	* {@code Error}, not {@code ExecutionException}.
399	>	*
400	>	* @return the computed result
401		*/
402	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
403	<	int s;
297	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
298	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
299	<	pool.updateRunningCount(s);
402	>	public final V join() {
403	>	return reportResult(waitingJoin());
404		}
405
406		/**
407	<	* Notify pool to adjust counts on cancelled or timed out wait
407	>	* Commences performing this task, awaits its completion if
408	>	* necessary, and return its result, or throws an (unchecked)
409	>	* exception if the underlying computation did so.
410	>	*
411	>	* @return the computed result
412		*/
413	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
414	<	if (pool != null) {
307	<	int s;
308	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
309	<	if (casStatus(s, s - 1)) {
310	<	pool.updateRunningCount(1);
311	<	break;
312	<	}
313	<	}
314	<	}
315	<	}
316	<
317	<	private void onInterruptedWait() {
318	<	Thread t = Thread.currentThread();
319	<	if (t instanceof ForkJoinWorkerThread) {
320	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)t;
321	<	if (w.isTerminating())
322	<	cancelIgnoreExceptions();
323	<	}
324	<	else { // re-interrupt
325	<	try {
326	<	t.interrupt();
327	<	} catch (SecurityException ignore) {
328	<	}
329	<	}
413	>	public final V invoke() {
414	>	return reportResult(waitingInvoke());
415		}
416
417	<	// Recording and reporting exceptions
418	<
419	<	private void setDoneExceptionally(Throwable rex) {
420	<	exceptionMap.put(this, rex);
421	<	setCompletion(EXCEPTIONAL);
417	>	/**
418	>	* Forks the given tasks, returning when {@code isDone} holds for
419	>	* each task or an (unchecked) exception is encountered, in which
420	>	* case the exception is rethrown.  If either task encounters an
421	>	* exception, the other one may be, but is not guaranteed to be,
422	>	* cancelled.  If both tasks throw an exception, then this method
423	>	* throws one of them.  The individual status of each task may be
424	>	* checked using {@link #getException()} and related methods.
425	>	*
426	>	* <p>This method may be invoked only from within {@code
427	>	* ForkJoinTask} computations (as may be determined using method
428	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
429	>	* result in exceptions or errors, possibly including {@code
430	>	* ClassCastException}.
431	>	*
432	>	* @param t1 the first task
433	>	* @param t2 the second task
434	>	* @throws NullPointerException if any task is null
435	>	*/
436	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
437	>	t2.fork();
438	>	t1.invoke();
439	>	t2.join();
440		}
441
442		/**
443	<	* Throws the exception associated with status s;
444	<	* @throws the exception
443	>	* Forks the given tasks, returning when {@code isDone} holds for
444	>	* each task or an (unchecked) exception is encountered, in which
445	>	* case the exception is rethrown. If any task encounters an
446	>	* exception, others may be, but are not guaranteed to be,
447	>	* cancelled.  If more than one task encounters an exception, then
448	>	* this method throws any one of these exceptions.  The individual
449	>	* status of each task may be checked using {@link #getException()}
450	>	* and related methods.
451	>	*
452	>	* <p>This method may be invoked only from within {@code
453	>	* ForkJoinTask} computations (as may be determined using method
454	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
455	>	* result in exceptions or errors, possibly including {@code
456	>	* ClassCastException}.
457	>	*
458	>	* @param tasks the tasks
459	>	* @throws NullPointerException if any task is null
460		*/
461	<	private void reportException(int s) {
462	<	if ((s &= COMPLETION_MASK) < NORMAL) {
463	<	if (s == CANCELLED)
464	<	throw new CancellationException();
465	<	else
466	<	rethrowException(exceptionMap.get(this));
461	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
462	>	Throwable ex = null;
463	>	int last = tasks.length - 1;
464	>	for (int i = last; i >= 0; --i) {
465	>	ForkJoinTask<?> t = tasks[i];
466	>	if (t == null) {
467	>	if (ex == null)
468	>	ex = new NullPointerException();
469	>	}
470	>	else if (i != 0)
471	>	t.fork();
472	>	else if (t.waitingInvoke() < NORMAL && ex == null)
473	>	ex = t.getException();
474		}
475	+	for (int i = 1; i <= last; ++i) {
476	+	ForkJoinTask<?> t = tasks[i];
477	+	if (t != null) {
478	+	if (ex != null)
479	+	t.cancel(false);
480	+	else if (t.waitingJoin() < NORMAL && ex == null)
481	+	ex = t.getException();
482	+	}
483	+	}
484	+	if (ex != null)
485	+	UNSAFE.throwException(ex);
486		}
487
488		/**
489	<	* Returns result or throws exception using j.u.c.Future conventions
490	<	* Only call when isDone known to be true.
489	>	* Forks all tasks in the specified collection, returning when
490	>	* {@code isDone} holds for each task or an (unchecked) exception
491	>	* is encountered.  If any task encounters an exception, others
492	>	* may be, but are not guaranteed to be, cancelled.  If more than
493	>	* one task encounters an exception, then this method throws any
494	>	* one of these exceptions.  The individual status of each task
495	>	* may be checked using {@link #getException()} and related
496	>	* methods.  The behavior of this operation is undefined if the
497	>	* specified collection is modified while the operation is in
498	>	* progress.
499	>	*
500	>	* <p>This method may be invoked only from within {@code
501	>	* ForkJoinTask} computations (as may be determined using method
502	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
503	>	* result in exceptions or errors, possibly including {@code
504	>	* ClassCastException}.
505	>	*
506	>	* @param tasks the collection of tasks
507	>	* @return the tasks argument, to simplify usage
508	>	* @throws NullPointerException if tasks or any element are null
509		*/
510	<	private V reportFutureResult()
511	<	throws ExecutionException, InterruptedException {
512	<	int s = status & COMPLETION_MASK;
513	<	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();
510	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
511	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
512	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
513	>	return tasks;
514		}
515	<	return getRawResult();
515	>	@SuppressWarnings("unchecked")
516	>	List<? extends ForkJoinTask<?>> ts =
517	>	(List<? extends ForkJoinTask<?>>) tasks;
518	>	Throwable ex = null;
519	>	int last = ts.size() - 1;
520	>	for (int i = last; i >= 0; --i) {
521	>	ForkJoinTask<?> t = ts.get(i);
522	>	if (t == null) {
523	>	if (ex == null)
524	>	ex = new NullPointerException();
525	>	}
526	>	else if (i != 0)
527	>	t.fork();
528	>	else if (t.waitingInvoke() < NORMAL && ex == null)
529	>	ex = t.getException();
530	>	}
531	>	for (int i = 1; i <= last; ++i) {
532	>	ForkJoinTask<?> t = ts.get(i);
533	>	if (t != null) {
534	>	if (ex != null)
535	>	t.cancel(false);
536	>	else if (t.waitingJoin() < NORMAL && ex == null)
537	>	ex = t.getException();
538	>	}
539	>	}
540	>	if (ex != null)
541	>	UNSAFE.throwException(ex);
542	>	return tasks;
543		}
544
545		/**
546	<	* Returns result or throws exception using j.u.c.Future conventions
547	<	* with timeouts
546	>	* Attempts to cancel execution of this task. This attempt will
547	>	* fail if the task has already completed, has already been
548	>	* cancelled, or could not be cancelled for some other reason. If
549	>	* successful, and this task has not started when cancel is
550	>	* called, execution of this task is suppressed, {@link
551	>	* #isCancelled} will report true, and {@link #join} will result
552	>	* in a {@code CancellationException} being thrown.
553	>	*
554	>	* <p>This method may be overridden in subclasses, but if so, must
555	>	* still ensure that these minimal properties hold. In particular,
556	>	* the {@code cancel} method itself must not throw exceptions.
557	>	*
558	>	* <p>This method is designed to be invoked by <em>other</em>
559	>	* tasks. To terminate the current task, you can just return or
560	>	* throw an unchecked exception from its computation method, or
561	>	* invoke {@link #completeExceptionally}.
562	>	*
563	>	* @param mayInterruptIfRunning this value is ignored in the
564	>	* default implementation because tasks are not
565	>	* cancelled via interruption
566	>	*
567	>	* @return {@code true} if this task is now cancelled
568		*/
569	<	private V reportTimedFutureResult()
570	<	throws InterruptedException, ExecutionException, TimeoutException {
571	<	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();
569	>	public boolean cancel(boolean mayInterruptIfRunning) {
570	>	setCompletion(CANCELLED);
571	>	return (status & COMPLETION_MASK) == CANCELLED;
572		}
573
390	–	// internal execution methods
391	–
574		/**
575	<	* Calls exec, recording completion, and rethrowing exception if
576	<	* encountered. Caller should normally check status before calling
395	<	* @return true if completed normally
575	>	* Cancels, ignoring any exceptions it throws. Used during worker
576	>	* and pool shutdown.
577		*/
578	<	private boolean tryExec() {
579	<	try { // try block must contain only call to exec
580	<	if (!exec())
581	<	return false;
401	<	} catch (Throwable rex) {
402	<	setDoneExceptionally(rex);
403	<	rethrowException(rex);
404	<	return false; // not reached
578	>	final void cancelIgnoringExceptions() {
579	>	try {
580	>	cancel(false);
581	>	} catch (Throwable ignore) {
582		}
406	–	setNormalCompletion();
407	–	return true;
583		}
584
585		/**
586	<	* Main execution method used by worker threads. Invokes
412	<	* base computation unless already complete
586	>	* Cancels ignoring exceptions if worker is terminating
587		*/
588	<	final void quietlyExec() {
589	<	if (status >= 0) {
588	>	private void cancelIfTerminating() {
589	>	Thread t = Thread.currentThread();
590	>	if ((t instanceof ForkJoinWorkerThread) &&
591	>	((ForkJoinWorkerThread) t).isTerminating()) {
592		try {
593	<	if (!exec())
594	<	return;
419	<	} catch(Throwable rex) {
420	<	setDoneExceptionally(rex);
421	<	return;
593	>	cancel(false);
594	>	} catch (Throwable ignore) {
595		}
423	–	setNormalCompletion();
596		}
597		}
598
599	+	public final boolean isDone() {
600	+	return status < 0;
601	+	}
602	+
603	+	public final boolean isCancelled() {
604	+	return (status & COMPLETION_MASK) == CANCELLED;
605	+	}
606	+
607		/**
608	<	* Calls exec, recording but not rethrowing exception
609	<	* Caller should normally check status before calling
610	<	* @return true if completed normally
608	>	* Returns {@code true} if this task threw an exception or was cancelled.
609	>	*
610	>	* @return {@code true} if this task threw an exception or was cancelled
611		*/
612	<	private boolean tryQuietlyInvoke() {
613	<	try {
434	<	if (!exec())
435	<	return false;
436	<	} catch (Throwable rex) {
437	<	setDoneExceptionally(rex);
438	<	return false;
439	<	}
440	<	setNormalCompletion();
441	<	return true;
612	>	public final boolean isCompletedAbnormally() {
613	>	return (status & COMPLETION_MASK) < NORMAL;
614		}
615
616		/**
617	<	* Cancel, ignoring any exceptions it throws
617	>	* Returns {@code true} if this task completed without throwing an
618	>	* exception and was not cancelled.
619	>	*
620	>	* @return {@code true} if this task completed without throwing an
621	>	* exception and was not cancelled
622		*/
623	<	final void cancelIgnoreExceptions() {
624	<	try {
449	<	cancel(false);
450	<	} catch(Throwable ignore) {
451	<	}
623	>	public final boolean isCompletedNormally() {
624	>	return (status & COMPLETION_MASK) == NORMAL;
625		}
626
627	<	// public methods
627	>	/**
628	>	* Returns the exception thrown by the base computation, or a
629	>	* {@code CancellationException} if cancelled, or {@code null} if
630	>	* none or if the method has not yet completed.
631	>	*
632	>	* @return the exception, or {@code null} if none
633	>	*/
634	>	public final Throwable getException() {
635	>	int s = status & COMPLETION_MASK;
636	>	return ((s >= NORMAL)    ? null :
637	>	(s == CANCELLED) ? new CancellationException() :
638	>	exceptionMap.get(this));
639	>	}
640
641		/**
642	<	* Arranges to asynchronously execute this task.  While it is not
643	<	* necessarily enforced, it is a usage error to fork a task more
644	<	* than once unless it has completed and been reinitialized.  This
645	<	* method may be invoked only from within other ForkJoinTask
646	<	* computations. Attempts to invoke in other contexts result in
647	<	* exceptions or errors including ClassCastException.
642	>	* Completes this task abnormally, and if not already aborted or
643	>	* cancelled, causes it to throw the given exception upon
644	>	* {@code join} and related operations. This method may be used
645	>	* to induce exceptions in asynchronous tasks, or to force
646	>	* completion of tasks that would not otherwise complete.  Its use
647	>	* in other situations is discouraged.  This method is
648	>	* overridable, but overridden versions must invoke {@code super}
649	>	* implementation to maintain guarantees.
650	>	*
651	>	* @param ex the exception to throw. If this exception is not a
652	>	* {@code RuntimeException} or {@code Error}, the actual exception
653	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
654		*/
655	<	public final void fork() {
656	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
655	>	public void completeExceptionally(Throwable ex) {
656	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
657	>	(ex instanceof Error) ? ex :
658	>	new RuntimeException(ex));
659		}
660
661		/**
662	<	* Returns the result of the computation when it is ready.
663	<	* This method differs from <tt>get</tt> in that abnormal
664	<	* completion results in RuntimeExceptions or Errors, not
665	<	* ExecutionExceptions.
662	>	* Completes this task, and if not already aborted or cancelled,
663	>	* returning a {@code null} result upon {@code join} and related
664	>	* operations. This method may be used to provide results for
665	>	* asynchronous tasks, or to provide alternative handling for
666	>	* tasks that would not otherwise complete normally. Its use in
667	>	* other situations is discouraged. This method is
668	>	* overridable, but overridden versions must invoke {@code super}
669	>	* implementation to maintain guarantees.
670		*
671	<	* @return the computed result
671	>	* @param value the result value for this task
672		*/
673	<	public final V join() {
674	<	ForkJoinWorkerThread w = getWorker();
675	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
676	<	reportException(awaitDone(w, true));
677	<	return getRawResult();
673	>	public void complete(V value) {
674	>	try {
675	>	setRawResult(value);
676	>	} catch (Throwable rex) {
677	>	setExceptionalCompletion(rex);
678	>	return;
679	>	}
680	>	setCompletion(NORMAL);
681		}
682
683		public final V get() throws InterruptedException, ExecutionException {
684	<	ForkJoinWorkerThread w = getWorker();
685	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
686	<	awaitDone(w, true);
687	<	return reportFutureResult();
684	>	int s = waitingJoin() & COMPLETION_MASK;
685	>	if (Thread.interrupted())
686	>	throw new InterruptedException();
687	>	if (s < NORMAL) {
688	>	Throwable ex;
689	>	if (s == CANCELLED)
690	>	throw new CancellationException();
691	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
692	>	throw new ExecutionException(ex);
693	>	}
694	>	return getRawResult();
695		}
696
697		public final V get(long timeout, TimeUnit unit)
698		throws InterruptedException, ExecutionException, TimeoutException {
699	<	ForkJoinWorkerThread w = getWorker();
700	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
701	<	awaitDone(w, unit.toNanos(timeout));
702	<	return reportTimedFutureResult();
699	>	Thread t = Thread.currentThread();
700	>	ForkJoinPool pool;
701	>	if (t instanceof ForkJoinWorkerThread) {
702	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
703	>	if (status >= 0 && w.unpushTask(this))
704	>	tryExec();
705	>	pool = w.pool;
706	>	}
707	>	else
708	>	pool = null;
709	>	/*
710	>	* Timed wait loop intermixes cases for fj (pool != null) and
711	>	* non FJ threads. For FJ, decrement pool count but don't try
712	>	* for replacement; increment count on completion. For non-FJ,
713	>	* deal with interrupts. This is messy, but a little less so
714	>	* than is splitting the FJ and nonFJ cases.
715	>	*/
716	>	boolean interrupted = false;
717	>	boolean dec = false; // true if pool count decremented
718	>	for (;;) {
719	>	if (Thread.interrupted() && pool == null) {
720	>	interrupted = true;
721	>	break;
722	>	}
723	>	int s = status;
724	>	if (s < 0)
725	>	break;
726	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
727	>	s, s | SIGNAL)) {
728	>	long startTime = System.nanoTime();
729	>	long nanos = unit.toNanos(timeout);
730	>	long nt; // wait time
731	>	while (status >= 0 &&
732	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
733	>	if (pool != null && !dec)
734	>	dec = pool.tryDecrementRunningCount();
735	>	else {
736	>	long ms = nt / 1000000;
737	>	int ns = (int) (nt % 1000000);
738	>	try {
739	>	synchronized(this) {
740	>	if (status >= 0)
741	>	wait(ms, ns);
742	>	}
743	>	} catch (InterruptedException ie) {
744	>	if (pool != null)
745	>	cancelIfTerminating();
746	>	else {
747	>	interrupted = true;
748	>	break;
749	>	}
750	>	}
751	>	}
752	>	}
753	>	break;
754	>	}
755	>	}
756	>	if (pool != null && dec)
757	>	pool.updateRunningCount(1);
758	>	if (interrupted)
759	>	throw new InterruptedException();
760	>	int es = status & COMPLETION_MASK;
761	>	if (es != NORMAL) {
762	>	Throwable ex;
763	>	if (es == CANCELLED)
764	>	throw new CancellationException();
765	>	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
766	>	throw new ExecutionException(ex);
767	>	throw new TimeoutException();
768	>	}
769	>	return getRawResult();
770		}
771
772		/**
773	<	* Possibly executes other tasks until this task is ready, then
774	<	* returns the result of the computation.  This method may be more
775	<	* efficient than <tt>join</tt>, but is only applicable when there
776	<	* are no potemtial dependencies between continuation of the
777	<	* current task and that of any other task that might be executed
778	<	* while helping. (This usually holds for pure divide-and-conquer
779	<	* tasks).
773	>	* Possibly executes other tasks until this task {@link #isDone is
774	>	* done}, then returns the result of the computation.  This method
775	>	* may be more efficient than {@code join}, but is only applicable
776	>	* when there are no potential dependencies between continuation
777	>	* of the current task and that of any other task that might be
778	>	* executed while helping. (This usually holds for pure
779	>	* divide-and-conquer tasks).
780	>	*
781	>	* <p>This method may be invoked only from within {@code
782	>	* ForkJoinTask} computations (as may be determined using method
783	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
784	>	* result in exceptions or errors, possibly including {@code
785	>	* ClassCastException}.
786	>	*
787		* @return the computed result
788		*/
789		public final V helpJoin() {
790	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
510	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
511	<	reportException(w.helpJoinTask(this));
512	<	return getRawResult();
790	>	return reportResult(busyJoin());
791		}
792
793		/**
794	<	* Performs this task, awaits its completion if necessary, and
795	<	* return its result.
796	<	* @throws Throwable (a RuntimeException, Error, or unchecked
797	<	* exception) if the underlying computation did so.
798	<	* @return the computed result
794	>	* Possibly executes other tasks until this task {@link #isDone is
795	>	* done}.  This method may be useful when processing collections
796	>	* of tasks when some have been cancelled or otherwise known to
797	>	* have aborted.
798	>	*
799	>	* <p>This method may be invoked only from within {@code
800	>	* ForkJoinTask} computations (as may be determined using method
801	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
802	>	* result in exceptions or errors, possibly including {@code
803	>	* ClassCastException}.
804		*/
805	<	public final V invoke() {
806	<	if (status >= 0 && tryExec())
524	<	return getRawResult();
525	<	else
526	<	return join();
805	>	public final void quietlyHelpJoin() {
806	>	busyJoin();
807		}
808
809		/**
#	Line 533 | Line 813 | public abstract class ForkJoinTask<V> im
813		* known to have aborted.
814		*/
815		public final void quietlyJoin() {
816	<	if (status >= 0) {
537	<	ForkJoinWorkerThread w = getWorker();
538	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
539	<	awaitDone(w, true);
540	<	}
816	>	waitingJoin();
817		}
818
819		/**
820	<	* Possibly executes other tasks until this task is ready.
820	>	* Commences performing this task and awaits its completion if
821	>	* necessary, without returning its result or throwing an
822	>	* exception. This method may be useful when processing
823	>	* collections of tasks when some have been cancelled or otherwise
824	>	* known to have aborted.
825		*/
826	<	public final void quietlyHelpJoin() {
827	<	if (status >= 0) {
548	<	ForkJoinWorkerThread w =
549	<	(ForkJoinWorkerThread)(Thread.currentThread());
550	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
551	<	w.helpJoinTask(this);
552	<	}
826	>	public final void quietlyInvoke() {
827	>	waitingInvoke();
828		}
829
830		/**
831	<	* Performs this task and awaits its completion if necessary,
832	<	* without returning its result or throwing an exception. This
833	<	* method may be useful when processing collections of tasks when
834	<	* some have been cancelled or otherwise known to have aborted.
831	>	* Possibly executes tasks until the pool hosting the current task
832	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
833	>	* be of use in designs in which many tasks are forked, but none
834	>	* are explicitly joined, instead executing them until all are
835	>	* processed.
836	>	*
837	>	* <p>This method may be invoked only from within {@code
838	>	* ForkJoinTask} computations (as may be determined using method
839	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
840	>	* result in exceptions or errors, possibly including {@code
841	>	* ClassCastException}.
842		*/
843	<	public final void quietlyInvoke() {
844	<	if (status >= 0 && !tryQuietlyInvoke())
845	<	quietlyJoin();
843	>	public static void helpQuiesce() {
844	>	((ForkJoinWorkerThread) Thread.currentThread())
845	>	.helpQuiescePool();
846		}
847
848		/**
849	<	* Returns true if the computation performed by this task has
850	<	* completed (or has been cancelled).
851	<	* @return true if this computation has completed
849	>	* Resets the internal bookkeeping state of this task, allowing a
850	>	* subsequent {@code fork}. This method allows repeated reuse of
851	>	* this task, but only if reuse occurs when this task has either
852	>	* never been forked, or has been forked, then completed and all
853	>	* outstanding joins of this task have also completed. Effects
854	>	* under any other usage conditions are not guaranteed.
855	>	* This method may be useful when executing
856	>	* pre-constructed trees of subtasks in loops.
857		*/
858	<	public final boolean isDone() {
859	<	return status < 0;
858	>	public void reinitialize() {
859	>	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
860	>	exceptionMap.remove(this);
861	>	status = 0;
862		}
863
864		/**
865	<	* Returns true if this task was cancelled.
866	<	* @return true if this task was cancelled
865	>	* Returns the pool hosting the current task execution, or null
866	>	* if this task is executing outside of any ForkJoinPool.
867	>	*
868	>	* @see #inForkJoinPool
869	>	* @return the pool, or {@code null} if none
870		*/
871	<	public final boolean isCancelled() {
872	<	return (status & COMPLETION_MASK) == CANCELLED;
871	>	public static ForkJoinPool getPool() {
872	>	Thread t = Thread.currentThread();
873	>	return (t instanceof ForkJoinWorkerThread) ?
874	>	((ForkJoinWorkerThread) t).pool : null;
875		}
876
877		/**
878	<	* Returns true if this task threw an exception or was cancelled
879	<	* @return true if this task threw an exception or was cancelled
878	>	* Returns {@code true} if the current thread is executing as a
879	>	* ForkJoinPool computation.
880	>	*
881	>	* @return {@code true} if the current thread is executing as a
882	>	* ForkJoinPool computation, or false otherwise
883		*/
884	<	public final boolean completedAbnormally() {
885	<	return (status & COMPLETION_MASK) < NORMAL;
884	>	public static boolean inForkJoinPool() {
885	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
886		}
887
888		/**
889	<	* Returns the exception thrown by the base computation, or a
890	<	* CancellationException if cancelled, or null if none or if the
891	<	* method has not yet completed.
892	<	* @return the exception, or null if none
889	>	* Tries to unschedule this task for execution. This method will
890	>	* typically succeed if this task is the most recently forked task
891	>	* by the current thread, and has not commenced executing in
892	>	* another thread.  This method may be useful when arranging
893	>	* alternative local processing of tasks that could have been, but
894	>	* were not, stolen.
895	>	*
896	>	* <p>This method may be invoked only from within {@code
897	>	* ForkJoinTask} computations (as may be determined using method
898	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
899	>	* result in exceptions or errors, possibly including {@code
900	>	* ClassCastException}.
901	>	*
902	>	* @return {@code true} if unforked
903		*/
904	<	public final Throwable getException() {
905	<	int s = status & COMPLETION_MASK;
906	<	if (s >= NORMAL)
600	<	return null;
601	<	if (s == CANCELLED)
602	<	return new CancellationException();
603	<	return exceptionMap.get(this);
904	>	public boolean tryUnfork() {
905	>	return ((ForkJoinWorkerThread) Thread.currentThread())
906	>	.unpushTask(this);
907		}
908
909		/**
910	<	* Asserts that the results of this task's computation will not be
911	<	* used. If a cancellation occurs before this task is processed,
912	<	* then its <tt>compute</tt> method will not be executed,
913	<	* <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.
910	>	* Returns an estimate of the number of tasks that have been
911	>	* forked by the current worker thread but not yet executed. This
912	>	* value may be useful for heuristic decisions about whether to
913	>	* fork other tasks.
914		*
915	<	* <p>This method may be overridden in subclasses, but if so, must
916	<	* still ensure that these minimal properties hold. In particular,
917	<	* the cancel method itself must not throw exceptions.
915	>	* <p>This method may be invoked only from within {@code
916	>	* ForkJoinTask} computations (as may be determined using method
917	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
918	>	* result in exceptions or errors, possibly including {@code
919	>	* ClassCastException}.
920		*
921	<	* <p> This method is designed to be invoked by <em>other</em>
922	<	* tasks. To terminate the current task, you can just return or
923	<	* throw an unchecked exception from its computation method, or
924	<	* invoke <tt>completeExceptionally(someException)</tt>.
921	>	* @return the number of tasks
922	>	*/
923	>	public static int getQueuedTaskCount() {
924	>	return ((ForkJoinWorkerThread) Thread.currentThread())
925	>	.getQueueSize();
926	>	}
927	>
928	>	/**
929	>	* Returns an estimate of how many more locally queued tasks are
930	>	* held by the current worker thread than there are other worker
931	>	* threads that might steal them.  This value may be useful for
932	>	* heuristic decisions about whether to fork other tasks. In many
933	>	* usages of ForkJoinTasks, at steady state, each worker should
934	>	* aim to maintain a small constant surplus (for example, 3) of
935	>	* tasks, and to process computations locally if this threshold is
936	>	* exceeded.
937		*
938	<	* @param mayInterruptIfRunning this value is ignored in the
939	<	* default implementation because tasks are not in general
940	<	* cancelled via interruption.
938	>	* <p>This method may be invoked only from within {@code
939	>	* ForkJoinTask} computations (as may be determined using method
940	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
941	>	* result in exceptions or errors, possibly including {@code
942	>	* ClassCastException}.
943		*
944	<	* @return true if this task is now cancelled
944	>	* @return the surplus number of tasks, which may be negative
945		*/
946	<	public boolean cancel(boolean mayInterruptIfRunning) {
947	<	setCompletion(CANCELLED);
948	<	return (status & COMPLETION_MASK) == CANCELLED;
946	>	public static int getSurplusQueuedTaskCount() {
947	>	return ((ForkJoinWorkerThread) Thread.currentThread())
948	>	.getEstimatedSurplusTaskCount();
949		}
950
951	+	// Extension methods
952	+
953		/**
954	<	* Completes this task abnormally, and if not already aborted or
955	<	* cancelled, causes it to throw the given exception upon
956	<	* <tt>join</tt> and related operations. This method may be used
957	<	* to induce exceptions in asynchronous tasks, or to force
958	<	* completion of tasks that would not otherwise complete.  This
959	<	* method is overridable, but overridden versions must invoke
960	<	* <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.
954	>	* Returns the result that would be returned by {@link #join}, even
955	>	* if this task completed abnormally, or {@code null} if this task
956	>	* is not known to have been completed.  This method is designed
957	>	* to aid debugging, as well as to support extensions. Its use in
958	>	* any other context is discouraged.
959	>	*
960	>	* @return the result, or {@code null} if not completed
961		*/
962	<	public void completeExceptionally(Throwable ex) {
651	<	setDoneExceptionally((ex instanceof RuntimeException) ||
652	<	(ex instanceof Error)? ex :
653	<	new RuntimeException(ex));
654	<	}
962	>	public abstract V getRawResult();
963
964		/**
965	<	* Completes this task, and if not already aborted or cancelled,
966	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
967	<	* 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.
965	>	* Forces the given value to be returned as a result.  This method
966	>	* is designed to support extensions, and should not in general be
967	>	* called otherwise.
968		*
969	<	* @param value the result value for this task.
969	>	* @param value the value
970		*/
971	<	public void complete(V value) {
666	<	try {
667	<	setRawResult(value);
668	<	} catch(Throwable rex) {
669	<	setDoneExceptionally(rex);
670	<	return;
671	<	}
672	<	setNormalCompletion();
673	<	}
971	>	protected abstract void setRawResult(V value);
972
973		/**
974	<	* Resets the internal bookkeeping state of this task, allowing a
975	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
976	<	* this task, but only if reuse occurs when this task has either
977	<	* never been forked, or has been forked, then completed and all
978	<	* outstanding joins of this task have also completed. Effects
979	<	* under any other usage conditions are not guaranteed, and are
980	<	* almost surely wrong. This method may be useful when executing
981	<	* pre-constructed trees of subtasks in loops.
974	>	* Immediately performs the base action of this task.  This method
975	>	* is designed to support extensions, and should not in general be
976	>	* called otherwise. The return value controls whether this task
977	>	* is considered to be done normally. It may return false in
978	>	* asynchronous actions that require explicit invocations of
979	>	* {@link #complete} to become joinable. It may also throw an
980	>	* (unchecked) exception to indicate abnormal exit.
981	>	*
982	>	* @return {@code true} if completed normally
983		*/
984	<	public void reinitialize() {
686	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
687	<	exceptionMap.remove(this);
688	<	status = 0;
689	<	}
984	>	protected abstract boolean exec();
985
986		/**
987	<	* Tries to unschedule this task for execution. This method will
988	<	* typically succeed if this task is the next task that would be
989	<	* executed by the current thread, and will typically fail (return
990	<	* false) otherwise. This method may be useful when arranging
991	<	* faster local processing of tasks that could have been, but were
992	<	* not, stolen.
993	<	* @return true if unforked
987	>	* Returns, but does not unschedule or execute, a task queued by
988	>	* the current thread but not yet executed, if one is immediately
989	>	* available. There is no guarantee that this task will actually
990	>	* be polled or executed next. Conversely, this method may return
991	>	* null even if a task exists but cannot be accessed without
992	>	* contention with other threads.  This method is designed
993	>	* primarily to support extensions, and is unlikely to be useful
994	>	* otherwise.
995	>	*
996	>	* <p>This method may be invoked only from within {@code
997	>	* ForkJoinTask} computations (as may be determined using method
998	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
999	>	* result in exceptions or errors, possibly including {@code
1000	>	* ClassCastException}.
1001	>	*
1002	>	* @return the next task, or {@code null} if none are available
1003		*/
1004	<	public boolean tryUnfork() {
1005	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
1004	>	protected static ForkJoinTask<?> peekNextLocalTask() {
1005	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1006	>	.peekTask();
1007		}
1008
1009		/**
1010	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
1011	<	* of them or an exception is encountered. This method may be
1012	<	* invoked only from within other ForkJoinTask
1013	<	* computations. Attempts to invoke in other contexts result in
1014	<	* exceptions or errors including ClassCastException.
1015	<	* @param t1 one task
1016	<	* @param t2 the other task
1017	<	* @throws NullPointerException if t1 or t2 are null
1018	<	* @throws RuntimeException or Error if either task did so.
1010	>	* Unschedules and returns, without executing, the next task
1011	>	* queued by the current thread but not yet executed.  This method
1012	>	* is designed primarily to support extensions, and is unlikely to
1013	>	* be useful otherwise.
1014	>	*
1015	>	* <p>This method may be invoked only from within {@code
1016	>	* ForkJoinTask} computations (as may be determined using method
1017	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1018	>	* result in exceptions or errors, possibly including {@code
1019	>	* ClassCastException}.
1020	>	*
1021	>	* @return the next task, or {@code null} if none are available
1022		*/
1023	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
1024	<	t2.fork();
1025	<	t1.invoke();
718	<	t2.join();
1023	>	protected static ForkJoinTask<?> pollNextLocalTask() {
1024	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1025	>	.pollLocalTask();
1026		}
1027
1028		/**
1029	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
1030	<	* all of them. If any task encounters an exception, others may be
1031	<	* cancelled.  This method may be invoked only from within other
1032	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1033	<	* result in exceptions or errors including ClassCastException.
1034	<	* @param tasks the array of tasks
1035	<	* @throws NullPointerException if tasks or any element are null.
1036	<	* @throws RuntimeException or Error if any task did so.
1029	>	* Unschedules and returns, without executing, the next task
1030	>	* queued by the current thread but not yet executed, if one is
1031	>	* available, or if not available, a task that was forked by some
1032	>	* other thread, if available. Availability may be transient, so a
1033	>	* {@code null} result does not necessarily imply quiescence
1034	>	* of the pool this task is operating in.  This method is designed
1035	>	* primarily to support extensions, and is unlikely to be useful
1036	>	* otherwise.
1037	>	*
1038	>	* <p>This method may be invoked only from within {@code
1039	>	* ForkJoinTask} computations (as may be determined using method
1040	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1041	>	* result in exceptions or errors, possibly including {@code
1042	>	* ClassCastException}.
1043	>	*
1044	>	* @return a task, or {@code null} if none are available
1045		*/
1046	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
1047	<	Throwable ex = null;
1048	<	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);
1046	>	protected static ForkJoinTask<?> pollTask() {
1047	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1048	>	.pollTask();
1049		}
1050
1051		/**
1052	<	* Forks all tasks in the collection, returning when
1053	<	* <tt>isDone</tt> holds for all of them. If any task encounters
1054	<	* 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.
1052	>	* Adaptor for Runnables. This implements RunnableFuture
1053	>	* to be compliant with AbstractExecutorService constraints
1054	>	* when used in ForkJoinPool.
1055		*/
1056	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
1057	<	if (!(tasks instanceof List)) {
1058	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
1059	<	return;
1060	<	}
1061	<	List<? extends ForkJoinTask<?>> ts =
1062	<	(List<? extends ForkJoinTask<?>>)tasks;
1063	<	Throwable ex = null;
1064	<	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	<	}
1056	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1057	>	implements RunnableFuture<T> {
1058	>	final Runnable runnable;
1059	>	final T resultOnCompletion;
1060	>	T result;
1061	>	AdaptedRunnable(Runnable runnable, T result) {
1062	>	if (runnable == null) throw new NullPointerException();
1063	>	this.runnable = runnable;
1064	>	this.resultOnCompletion = result;
1065		}
1066	<	for (int i = 1; i <= last; ++i) {
1067	<	ForkJoinTask<?> t = ts.get(i);
1068	<	if (t != null) {
1069	<	if (ex != null)
1070	<	t.cancel(false);
1071	<	else {
804	<	t.quietlyJoin();
805	<	if (ex == null)
806	<	ex = t.getException();
807	<	}
808	<	}
1066	>	public T getRawResult() { return result; }
1067	>	public void setRawResult(T v) { result = v; }
1068	>	public boolean exec() {
1069	>	runnable.run();
1070	>	result = resultOnCompletion;
1071	>	return true;
1072		}
1073	<	if (ex != null)
1074	<	rethrowException(ex);
1073	>	public void run() { invoke(); }
1074	>	private static final long serialVersionUID = 5232453952276885070L;
1075		}
1076
1077		/**
1078	<	* 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.
1078	>	* Adaptor for Callables
1079		*/
1080	<	public static void helpQuiesce() {
1081	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1082	<	helpQuiescePool();
1080	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1081	>	implements RunnableFuture<T> {
1082	>	final Callable<? extends T> callable;
1083	>	T result;
1084	>	AdaptedCallable(Callable<? extends T> callable) {
1085	>	if (callable == null) throw new NullPointerException();
1086	>	this.callable = callable;
1087	>	}
1088	>	public T getRawResult() { return result; }
1089	>	public void setRawResult(T v) { result = v; }
1090	>	public boolean exec() {
1091	>	try {
1092	>	result = callable.call();
1093	>	return true;
1094	>	} catch (Error err) {
1095	>	throw err;
1096	>	} catch (RuntimeException rex) {
1097	>	throw rex;
1098	>	} catch (Exception ex) {
1099	>	throw new RuntimeException(ex);
1100	>	}
1101	>	}
1102	>	public void run() { invoke(); }
1103	>	private static final long serialVersionUID = 2838392045355241008L;
1104		}
1105
1106		/**
1107	<	* Returns a estimate of how many more locally queued tasks are
1108	<	* held by the current worker thread than there are other worker
1109	<	* threads that might want to steal them.  This value may be
1110	<	* useful for heuristic decisions about whether to fork other
1111	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
1112	<	* 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
1107	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1108	>	* method of the given {@code Runnable} as its action, and returns
1109	>	* a null result upon {@link #join}.
1110	>	*
1111	>	* @param runnable the runnable action
1112	>	* @return the task
1113		*/
1114	<	public static int surplus() {
1115	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
838	<	.getEstimatedSurplusTaskCount();
1114	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1115	>	return new AdaptedRunnable<Void>(runnable, null);
1116		}
1117
841	–	// Extension kit
842	–
1118		/**
1119	<	* Returns the result that would be returned by <tt>join</tt>, or
1120	<	* null if this task is not known to have been completed.  This
1121	<	* method is designed to aid debugging, as well as to support
847	<	* extensions. Its use in any other context is discouraged.
1119	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1120	>	* method of the given {@code Runnable} as its action, and returns
1121	>	* the given result upon {@link #join}.
1122		*
1123	<	* @return the result, or null if not completed.
1123	>	* @param runnable the runnable action
1124	>	* @param result the result upon completion
1125	>	* @return the task
1126		*/
1127	<	public abstract V getRawResult();
1127	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1128	>	return new AdaptedRunnable<T>(runnable, result);
1129	>	}
1130
1131		/**
1132	<	* Forces the given value to be returned as a result.  This method
1133	<	* is designed to support extensions, and should not in general be
1134	<	* called otherwise.
1132	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1133	>	* method of the given {@code Callable} as its action, and returns
1134	>	* its result upon {@link #join}, translating any checked exceptions
1135	>	* encountered into {@code RuntimeException}.
1136		*
1137	<	* @param value the value
1138	<	*/
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
1137	>	* @param callable the callable action
1138	>	* @return the task
1139		*/
1140	<	protected abstract boolean exec();
1140	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1141	>	return new AdaptedCallable<T>(callable);
1142	>	}
1143
1144		// Serialization support
1145
1146		private static final long serialVersionUID = -7721805057305804111L;
1147
1148		/**
1149	<	* Save the state to a stream.
1149	>	* Saves the state to a stream.
1150		*
1151		* @serialData the current run status and the exception thrown
1152	<	* during execution, or null if none.
1152	>	* during execution, or {@code null} if none
1153		* @param s the stream
1154		*/
1155		private void writeObject(java.io.ObjectOutputStream s)
#	Line 890 | Line 1159 | public abstract class ForkJoinTask<V> im
1159		}
1160
1161		/**
1162	<	* Reconstitute the instance from a stream.
1162	>	* Reconstitutes the instance from a stream.
1163	>	*
1164		* @param s the stream
1165		*/
1166		private void readObject(java.io.ObjectInputStream s)
1167		throws java.io.IOException, ClassNotFoundException {
1168		s.defaultReadObject();
1169	<	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1169	>	status |= SIGNAL; // conservatively set external signal
1170		Object ex = s.readObject();
1171		if (ex != null)
1172	<	setDoneExceptionally((Throwable)ex);
1172	>	setExceptionalCompletion((Throwable) ex);
1173		}
1174
1175	<	// Temporary Unsafe mechanics for preliminary release
1175	>	// Unsafe mechanics
1176
1177	<	static final Unsafe _unsafe;
1178	<	static final long statusOffset;
1177	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1178	>	private static final long statusOffset =
1179	>	objectFieldOffset("status", ForkJoinTask.class);
1180
1181	<	static {
1181	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1182		try {
1183	<	if (ForkJoinTask.class.getClassLoader() != null) {
1184	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1185	<	f.setAccessible(true);
1186	<	_unsafe = (Unsafe)f.get(null);
1187	<	}
1188	<	else
1189	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
920	<	(ForkJoinTask.class.getDeclaredField("status"));
921	<	} catch (Exception ex) { throw new Error(ex); }
1183	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1184	>	} catch (NoSuchFieldException e) {
1185	>	// Convert Exception to corresponding Error
1186	>	NoSuchFieldError error = new NoSuchFieldError(field);
1187	>	error.initCause(e);
1188	>	throw error;
1189	>	}
1190		}
1191
1192	+	/**
1193	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1194	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1195	+	* into a jdk.
1196	+	*
1197	+	* @return a sun.misc.Unsafe
1198	+	*/
1199	+	private static sun.misc.Unsafe getUnsafe() {
1200	+	try {
1201	+	return sun.misc.Unsafe.getUnsafe();
1202	+	} catch (SecurityException se) {
1203	+	try {
1204	+	return java.security.AccessController.doPrivileged
1205	+	(new java.security
1206	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1207	+	public sun.misc.Unsafe run() throws Exception {
1208	+	java.lang.reflect.Field f = sun.misc
1209	+	.Unsafe.class.getDeclaredField("theUnsafe");
1210	+	f.setAccessible(true);
1211	+	return (sun.misc.Unsafe) f.get(null);
1212	+	}});
1213	+	} catch (java.security.PrivilegedActionException e) {
1214	+	throw new RuntimeException("Could not initialize intrinsics",
1215	+	e.getCause());
1216	+	}
1217	+	}
1218	+	}
1219		}

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