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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 1.47 by dl, Sun Apr 18 12:51:18 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
163	>	* ForkJoinPool max thread limits). Signal counts are not directly
164	>	* incremented by ForkJoinTask methods, but instead via a call to
165	>	* requestSignal within ForkJoinPool.preJoin, once their need is
166	>	* established.
167	>	*
168	>	* Completion of a stolen task with SIGNAL_MASK bits set awakens
169	>	* any waiters via notifyAll. Even though suboptimal for some
170	>	* purposes, we use basic builtin wait/notify to take advantage of
171	>	* "monitor inflation" in JVMs that we would otherwise need to
172	>	* emulate to avoid adding further per-task bookkeeping overhead.
173	>	* We want these monitors to be "fat", i.e., not use biasing or
174	>	* thin-lock techniques, so use some odd coding idioms that tend
175	>	* to avoid them.
176	>	*
177	>	* Note that bits 16-28 are currently unused. Also value
178	>	* 0x80000000 is available as spare completion value.
179	>	*/
180	>	volatile int status; // accessed directly by pool and workers
181	>
182	>	private static final int COMPLETION_MASK      = 0xe0000000;
183	>	private static final int NORMAL               = 0xe0000000; // == mask
184	>	private static final int CANCELLED            = 0xc0000000;
185	>	private static final int EXCEPTIONAL          = 0xa0000000;
186	>	private static final int SIGNAL_MASK          = 0x0000ffff;
187	>	private static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
188	>	private static final int EXTERNAL_SIGNAL      = 0x00008000;
189
190		/**
191		* Table of exceptions thrown by tasks, to enable reporting by
192		* callers. Because exceptions are rare, we don't directly keep
193	<	* them with task objects, but instead us a weak ref table.  Note
193	>	* them with task objects, but instead use a weak ref table.  Note
194		* that cancellation exceptions don't appear in the table, but are
195		* instead recorded as status values.
196	<	* Todo: Use ConcurrentReferenceHashMap
196	>	* TODO: Use ConcurrentReferenceHashMap
197		*/
198		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
199		Collections.synchronizedMap
200		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
201
202	<	// 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	<	}
202	>	// Maintaining completion status
203
204		/**
205	<	* Get pool of current worker thread, or null if not a worker thread
205	>	* Marks completion and wakes up threads waiting to join this task,
206	>	* also clearing signal request bits.
207	>	*
208	>	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
209		*/
210	<	static ForkJoinPool getWorkerPool() {
211	<	Thread t = Thread.currentThread();
212	<	return ((t instanceof ForkJoinWorkerThread)?
213	<	((ForkJoinWorkerThread)t).pool : null);
214	<	}
215	<
216	<	final boolean casStatus(int cmp, int val) {
217	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
210	>	private void setCompletion(int completion) {
211	>	int s;
212	>	while ((s = status) >= 0) {
213	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
214	>	if ((s & SIGNAL_MASK) != 0) {
215	>	Thread t = Thread.currentThread();
216	>	if (t instanceof ForkJoinWorkerThread)
217	>	((ForkJoinWorkerThread) t).pool.updateRunningCount
218	>	(s & INTERNAL_SIGNAL_MASK);
219	>	synchronized (this) { notifyAll(); }
220	>	}
221	>	return;
222	>	}
223	>	}
224		}
225
226		/**
227	<	* Workaround for not being able to rethrow unchecked exceptions.
227	>	* Record exception and set exceptional completion
228		*/
229	<	static void rethrowException(Throwable ex) {
230	<	if (ex != null)
231	<	_unsafe.throwException(ex);
229	>	private void setDoneExceptionally(Throwable rex) {
230	>	exceptionMap.put(this, rex);
231	>	setCompletion(EXCEPTIONAL);
232		}
233
168	–	// Setting completion status
169	–
234		/**
235	<	* Mark completion and wake up threads waiting to join this task.
236	<	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
235	>	* Main internal execution method: Unless done, calls exec and
236	>	* records completion.
237	>	*
238	>	* @return true if ran and completed normally
239		*/
240	<	final void setCompletion(int completion) {
241	<	ForkJoinPool pool = getWorkerPool();
242	<	if (pool != null) {
243	<	int s; // Clear signal bits while setting completion status
244	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
245	<
246	<	if ((s & SIGNAL_MASK) != 0) {
181	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
182	<	pool.updateRunningCount(s);
183	<	synchronized(this) { notifyAll(); }
184	<	}
240	>	final boolean tryExec() {
241	>	try {
242	>	if (status < 0 || !exec())
243	>	return false;
244	>	} catch (Throwable rex) {
245	>	setDoneExceptionally(rex);
246	>	return false;
247		}
248	<	else
249	<	externallySetCompletion(completion);
248	>	setCompletion(NORMAL); // must be outside try block
249	>	return true;
250		}
251
252		/**
253	<	* Version of setCompletion for non-FJ threads.  Leaves signal
254	<	* bits for unblocked threads to adjust, and always notifies.
253	>	* Increments internal signal count (thus requesting signal upon
254	>	* completion) unless already done.  Call only once per join.
255	>	* Used by ForkJoinPool.preJoin.
256	>	*
257	>	* @return status
258		*/
259	<	private void externallySetCompletion(int completion) {
259	>	final int requestSignal() {
260		int s;
261	<	do;while ((s = status) >= 0 &&
262	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
263	<	synchronized(this) { notifyAll(); }
261	>	do {} while ((s = status) >= 0 &&
262	>	!UNSAFE.compareAndSwapInt(this, statusOffset, s, s + 1));
263	>	return s;
264		}
265
266		/**
267	<	* Sets status to indicate normal completion
267	>	* Sets external signal request unless already done.
268	>	*
269	>	* @return status
270		*/
271	<	final void setNormalCompletion() {
272	<	// Try typical fast case -- single CAS, no signal, not already done.
273	<	// Manually expand casStatus to improve chances of inlining it
274	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
275	<	setCompletion(NORMAL);
271	>	private int requestExternalSignal() {
272	>	int s;
273	>	do {} while ((s = status) >= 0 &&
274	>	!UNSAFE.compareAndSwapInt(this, statusOffset,
275	>	s, s | EXTERNAL_SIGNAL));
276	>	return s;
277		}
278
279	<	// internal waiting and notification
280	<
281	<	/**
282	<	* Performs the actual monitor wait for awaitDone
279	>	/*
280	>	* Awaiting completion. The four versions, internal vs external X
281	>	* untimed vs timed, have the same overall structure but differ
282	>	* from each other enough to defy simple integration.
283		*/
216	–	private void doAwaitDone() {
217	–	// Minimize lock bias and in/de-flation effects by maximizing
218	–	// 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	–	}
225	–	}
284
285		/**
286	<	* Performs the actual monitor wait for awaitDone
286	>	* Blocks a worker until this task is done, also maintaining pool
287	>	* and signal counts
288		*/
289	<	private void doAwaitDone(long startTime, long nanos) {
290	<	synchronized(this) {
291	<	try {
292	<	while (status >= 0) {
293	<	long nt = nanos - System.nanoTime() - startTime;
294	<	if (nt <= 0)
295	<	break;
296	<	wait(nt / 1000000, (int)(nt % 1000000));
289	>	private void awaitDone(ForkJoinWorkerThread w) {
290	>	if (status >= 0) {
291	>	w.pool.preJoin(this);
292	>	while (status >= 0) {
293	>	try { // minimize lock scope
294	>	synchronized(this) {
295	>	if (status >= 0)
296	>	wait();
297	>	else { // help release; also helps avoid lock-biasing
298	>	notifyAll();
299	>	break;
300	>	}
301	>	}
302	>	} catch (InterruptedException ie) {
303	>	cancelIfTerminating();
304		}
239	–	} catch (InterruptedException ie) {
240	–	onInterruptedWait();
305		}
306		}
307		}
308
245	–	// Awaiting completion
246	–
309		/**
310	<	* Sets status to indicate there is joiner, then waits for join,
249	<	* surrounded with pool notifications.
250	<	* @return status upon exit
310	>	* Blocks a non-ForkJoin thread until this task is done.
311		*/
312	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
313	<	ForkJoinPool pool = w == null? null : w.pool;
314	<	int s;
315	<	while ((s = status) >= 0) {
316	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
317	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
318	<	doAwaitDone();
319	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
320	<	adjustPoolCountsOnUnblock(pool);
321	<	break;
312	>	private void externalAwaitDone() {
313	>	if (requestExternalSignal() >= 0) {
314	>	boolean interrupted = false;
315	>	while (status >= 0) {
316	>	try {
317	>	synchronized(this) {
318	>	if (status >= 0)
319	>	wait();
320	>	else {
321	>	notifyAll();
322	>	break;
323	>	}
324	>	}
325	>	} catch (InterruptedException ie) {
326	>	interrupted = true;
327	>	}
328		}
329	+	if (interrupted)
330	+	Thread.currentThread().interrupt();
331		}
264	–	return s;
332		}
333
334		/**
335	<	* Timed version of awaitDone
269	<	* @return status upon exit
335	>	* Blocks a worker until this task is done or timeout elapses
336		*/
337	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
338	<	ForkJoinPool pool = w == null? null : w.pool;
339	<	int s;
340	<	while ((s = status) >= 0) {
341	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
342	<	long startTime = System.nanoTime();
343	<	if (pool == null || !pool.preJoin(this, false))
344	<	doAwaitDone(startTime, nanos);
345	<	if ((s = status) >= 0) {
346	<	adjustPoolCountsOnCancelledWait(pool);
347	<	s = status;
337	>	private void timedAwaitDone(ForkJoinWorkerThread w, long nanos) {
338	>	if (status >= 0) {
339	>	long startTime = System.nanoTime();
340	>	ForkJoinPool pool = w.pool;
341	>	pool.preJoin(this);
342	>	while (status >= 0) {
343	>	long nt = nanos - (System.nanoTime() - startTime);
344	>	if (nt > 0) {
345	>	long ms = nt / 1000000;
346	>	int ns = (int) (nt % 1000000);
347	>	try {
348	>	synchronized(this) { if (status >= 0) wait(ms, ns); }
349	>	} catch (InterruptedException ie) {
350	>	cancelIfTerminating();
351	>	}
352	>	}
353	>	else {
354	>	int s; // adjust running count on timeout
355	>	while ((s = status) >= 0 &&
356	>	(s & INTERNAL_SIGNAL_MASK) != 0) {
357	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
358	>	s, s - 1)) {
359	>	pool.updateRunningCount(1);
360	>	break;
361	>	}
362	>	}
363	>	break;
364		}
283	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
284	–	adjustPoolCountsOnUnblock(pool);
285	–	break;
365		}
366		}
288	–	return s;
289	–	}
290	–
291	–	/**
292	–	* Notify pool that thread is unblocked. Called by signalled
293	–	* threads when woken by non-FJ threads (which is atypical).
294	–	*/
295	–	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
296	–	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);
367		}
368
369		/**
370	<	* Notify pool to adjust counts on cancelled or timed out wait
370	>	* Blocks a non-ForkJoin thread until this task is done or timeout elapses
371		*/
372	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
373	<	if (pool != null) {
374	<	int s;
375	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
376	<	if (casStatus(s, s - 1)) {
377	<	pool.updateRunningCount(1);
372	>	private void externalTimedAwaitDone(long nanos) {
373	>	if (requestExternalSignal() >= 0) {
374	>	long startTime = System.nanoTime();
375	>	boolean interrupted = false;
376	>	while (status >= 0) {
377	>	long nt = nanos - (System.nanoTime() - startTime);
378	>	if (nt <= 0)
379		break;
380	+	long ms = nt / 1000000;
381	+	int ns = (int) (nt % 1000000);
382	+	try {
383	+	synchronized(this) { if (status >= 0) wait(ms, ns); }
384	+	} catch (InterruptedException ie) {
385	+	interrupted = true;
386		}
387		}
388	+	if (interrupted)
389	+	Thread.currentThread().interrupt();
390		}
391		}
392
393	<	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	<	}
330	<	}
331	<
332	<	// Recording and reporting exceptions
333	<
334	<	private void setDoneExceptionally(Throwable rex) {
335	<	exceptionMap.put(this, rex);
336	<	setCompletion(EXCEPTIONAL);
337	<	}
393	>	// reporting results
394
395		/**
396	<	* Throws the exception associated with status s;
397	<	* @throws the exception
396	>	* Returns result or throws the exception associated with status.
397	>	* Uses Unsafe as a workaround for javac not allowing rethrow of
398	>	* unchecked exceptions.
399		*/
400	<	private void reportException(int s) {
401	<	if ((s &= COMPLETION_MASK) < NORMAL) {
402	<	if (s == CANCELLED)
403	<	throw new CancellationException();
404	<	else
348	<	rethrowException(exceptionMap.get(this));
400	>	private V reportResult() {
401	>	if ((status & COMPLETION_MASK) < NORMAL) {
402	>	Throwable ex = getException();
403	>	if (ex != null)
404	>	UNSAFE.throwException(ex);
405		}
406	+	return getRawResult();
407		}
408
409		/**
410	<	* Returns result or throws exception using j.u.c.Future conventions
411	<	* Only call when isDone known to be true.
410	>	* Returns result or throws exception using j.u.c.Future conventions.
411	>	* Only call when {@code isDone} known to be true or thread known
412	>	* to be interrupted.
413		*/
414		private V reportFutureResult()
415	<	throws ExecutionException, InterruptedException {
415	>	throws InterruptedException, ExecutionException {
416	>	if (Thread.interrupted())
417	>	throw new InterruptedException();
418		int s = status & COMPLETION_MASK;
419		if (s < NORMAL) {
420		Throwable ex;
#	Line 362 | Line 422 | public abstract class ForkJoinTask<V> im
422		throw new CancellationException();
423		if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
424		throw new ExecutionException(ex);
365	–	if (Thread.interrupted())
366	–	throw new InterruptedException();
425		}
426		return getRawResult();
427		}
428
429		/**
430		* Returns result or throws exception using j.u.c.Future conventions
431	<	* with timeouts
431	>	* with timeouts.
432		*/
433		private V reportTimedFutureResult()
434		throws InterruptedException, ExecutionException, TimeoutException {
435	+	if (Thread.interrupted())
436	+	throw new InterruptedException();
437		Throwable ex;
438		int s = status & COMPLETION_MASK;
439		if (s == NORMAL)
440		return getRawResult();
441	<	if (s == CANCELLED)
441	>	else if (s == CANCELLED)
442		throw new CancellationException();
443	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
443	>	else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
444		throw new ExecutionException(ex);
445	<	if (Thread.interrupted())
446	<	throw new InterruptedException();
387	<	throw new TimeoutException();
388	<	}
389	<
390	<	// internal execution methods
391	<
392	<	/**
393	<	* Calls exec, recording completion, and rethrowing exception if
394	<	* encountered. Caller should normally check status before calling
395	<	* @return true if completed normally
396	<	*/
397	<	private boolean tryExec() {
398	<	try { // try block must contain only call to exec
399	<	if (!exec())
400	<	return false;
401	<	} catch (Throwable rex) {
402	<	setDoneExceptionally(rex);
403	<	rethrowException(rex);
404	<	return false; // not reached
405	<	}
406	<	setNormalCompletion();
407	<	return true;
408	<	}
409	<
410	<	/**
411	<	* Main execution method used by worker threads. Invokes
412	<	* base computation unless already complete
413	<	*/
414	<	final void quietlyExec() {
415	<	if (status >= 0) {
416	<	try {
417	<	if (!exec())
418	<	return;
419	<	} catch(Throwable rex) {
420	<	setDoneExceptionally(rex);
421	<	return;
422	<	}
423	<	setNormalCompletion();
424	<	}
425	<	}
426	<
427	<	/**
428	<	* Calls exec, recording but not rethrowing exception
429	<	* Caller should normally check status before calling
430	<	* @return true if completed normally
431	<	*/
432	<	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;
442	<	}
443	<
444	<	/**
445	<	* Cancel, ignoring any exceptions it throws
446	<	*/
447	<	final void cancelIgnoreExceptions() {
448	<	try {
449	<	cancel(false);
450	<	} catch(Throwable ignore) {
451	<	}
445	>	else
446	>	throw new TimeoutException();
447		}
448
449		// public methods
#	Line 456 | Line 451 | public abstract class ForkJoinTask<V> im
451		/**
452		* Arranges to asynchronously execute this task.  While it is not
453		* necessarily enforced, it is a usage error to fork a task more
454	<	* than once unless it has completed and been reinitialized.  This
455	<	* method may be invoked only from within other ForkJoinTask
456	<	* computations. Attempts to invoke in other contexts result in
457	<	* exceptions or errors including ClassCastException.
454	>	* than once unless it has completed and been reinitialized.
455	>	* Subsequent modifications to the state of this task or any data
456	>	* it operates on are not necessarily consistently observable by
457	>	* any thread other than the one executing it unless preceded by a
458	>	* call to {@link #join} or related methods, or a call to {@link
459	>	* #isDone} returning {@code true}.
460	>	*
461	>	* <p>This method may be invoked only from within {@code
462	>	* ForkJoinTask} computations (as may be determined using method
463	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
464	>	* result in exceptions or errors, possibly including {@code
465	>	* ClassCastException}.
466	>	*
467	>	* @return {@code this}, to simplify usage
468		*/
469	<	public final void fork() {
470	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
469	>	public final ForkJoinTask<V> fork() {
470	>	((ForkJoinWorkerThread) Thread.currentThread())
471	>	.pushTask(this);
472	>	return this;
473		}
474
475		/**
476	<	* Returns the result of the computation when it is ready.
477	<	* This method differs from <tt>get</tt> in that abnormal
478	<	* completion results in RuntimeExceptions or Errors, not
479	<	* ExecutionExceptions.
476	>	* Returns the result of the computation when it {@link #isDone is done}.
477	>	* This method differs from {@link #get()} in that
478	>	* abnormal completion results in {@code RuntimeException} or
479	>	* {@code Error}, not {@code ExecutionException}.
480		*
481		* @return the computed result
482		*/
483		public final V join() {
484	<	ForkJoinWorkerThread w = getWorker();
485	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
479	<	reportException(awaitDone(w, true));
480	<	return getRawResult();
481	<	}
482	<
483	<	public final V get() throws InterruptedException, ExecutionException {
484	<	ForkJoinWorkerThread w = getWorker();
485	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
486	<	awaitDone(w, true);
487	<	return reportFutureResult();
488	<	}
489	<
490	<	public final V get(long timeout, TimeUnit unit)
491	<	throws InterruptedException, ExecutionException, TimeoutException {
492	<	ForkJoinWorkerThread w = getWorker();
493	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
494	<	awaitDone(w, unit.toNanos(timeout));
495	<	return reportTimedFutureResult();
484	>	quietlyJoin();
485	>	return reportResult();
486		}
487
488		/**
489	<	* Possibly executes other tasks until this task is ready, then
490	<	* returns the result of the computation.  This method may be more
491	<	* efficient than <tt>join</tt>, but is only applicable when there
492	<	* 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).
489	>	* Commences performing this task, awaits its completion if
490	>	* necessary, and return its result, or throws an (unchecked)
491	>	* exception if the underlying computation did so.
492	>	*
493		* @return the computed result
494		*/
495	<	public final V helpJoin() {
496	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
497	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
498	<	reportException(w.helpJoinTask(this));
512	<	return getRawResult();
495	>	public final V invoke() {
496	>	if (!tryExec())
497	>	quietlyJoin();
498	>	return reportResult();
499		}
500
501		/**
502	<	* Performs this task, awaits its completion if necessary, and
503	<	* return its result.
504	<	* @throws Throwable (a RuntimeException, Error, or unchecked
505	<	* exception) if the underlying computation did so.
506	<	* @return the computed result
502	>	* Forks the given tasks, returning when {@code isDone} holds for
503	>	* each task or an (unchecked) exception is encountered, in which
504	>	* case the exception is rethrown.  If either task encounters an
505	>	* exception, the other one may be, but is not guaranteed to be,
506	>	* cancelled.  If both tasks throw an exception, then this method
507	>	* throws one of them.  The individual status of each task may be
508	>	* checked using {@link #getException()} and related methods.
509	>	*
510	>	* <p>This method may be invoked only from within {@code
511	>	* ForkJoinTask} computations (as may be determined using method
512	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
513	>	* result in exceptions or errors, possibly including {@code
514	>	* ClassCastException}.
515	>	*
516	>	* @param t1 the first task
517	>	* @param t2 the second task
518	>	* @throws NullPointerException if any task is null
519		*/
520	<	public final V invoke() {
521	<	if (status >= 0 && tryExec())
522	<	return getRawResult();
523	<	else
526	<	return join();
520	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
521	>	t2.fork();
522	>	t1.invoke();
523	>	t2.join();
524		}
525
526		/**
527	<	* Joins this task, without returning its result or throwing an
528	<	* exception. This method may be useful when processing
529	<	* collections of tasks when some have been cancelled or otherwise
530	<	* known to have aborted.
527	>	* Forks the given tasks, returning when {@code isDone} holds for
528	>	* each task or an (unchecked) exception is encountered, in which
529	>	* case the exception is rethrown. If any task encounters an
530	>	* exception, others may be, but are not guaranteed to be,
531	>	* cancelled.  If more than one task encounters an exception, then
532	>	* this method throws any one of these exceptions.  The individual
533	>	* status of each task may be checked using {@link #getException()}
534	>	* and related methods.
535	>	*
536	>	* <p>This method may be invoked only from within {@code
537	>	* ForkJoinTask} computations (as may be determined using method
538	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
539	>	* result in exceptions or errors, possibly including {@code
540	>	* ClassCastException}.
541	>	*
542	>	* @param tasks the tasks
543	>	* @throws NullPointerException if any task is null
544		*/
545	<	public final void quietlyJoin() {
546	<	if (status >= 0) {
547	<	ForkJoinWorkerThread w = getWorker();
548	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
549	<	awaitDone(w, true);
545	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
546	>	Throwable ex = null;
547	>	int last = tasks.length - 1;
548	>	for (int i = last; i >= 0; --i) {
549	>	ForkJoinTask<?> t = tasks[i];
550	>	if (t == null) {
551	>	if (ex == null)
552	>	ex = new NullPointerException();
553	>	}
554	>	else if (i != 0)
555	>	t.fork();
556	>	else {
557	>	t.quietlyInvoke();
558	>	if (ex == null)
559	>	ex = t.getException();
560	>	}
561	>	}
562	>	for (int i = 1; i <= last; ++i) {
563	>	ForkJoinTask<?> t = tasks[i];
564	>	if (t != null) {
565	>	if (ex != null)
566	>	t.cancel(false);
567	>	else {
568	>	t.quietlyJoin();
569	>	if (ex == null)
570	>	ex = t.getException();
571	>	}
572	>	}
573		}
574	+	if (ex != null)
575	+	UNSAFE.throwException(ex);
576		}
577
578		/**
579	<	* Possibly executes other tasks until this task is ready.
579	>	* Forks all tasks in the specified collection, returning when
580	>	* {@code isDone} holds for each task or an (unchecked) exception
581	>	* is encountered.  If any task encounters an exception, others
582	>	* may be, but are not guaranteed to be, cancelled.  If more than
583	>	* one task encounters an exception, then this method throws any
584	>	* one of these exceptions.  The individual status of each task
585	>	* may be checked using {@link #getException()} and related
586	>	* methods.  The behavior of this operation is undefined if the
587	>	* specified collection is modified while the operation is in
588	>	* progress.
589	>	*
590	>	* <p>This method may be invoked only from within {@code
591	>	* ForkJoinTask} computations (as may be determined using method
592	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
593	>	* result in exceptions or errors, possibly including {@code
594	>	* ClassCastException}.
595	>	*
596	>	* @param tasks the collection of tasks
597	>	* @return the tasks argument, to simplify usage
598	>	* @throws NullPointerException if tasks or any element are null
599		*/
600	<	public final void quietlyHelpJoin() {
601	<	if (status >= 0) {
602	<	ForkJoinWorkerThread w =
603	<	(ForkJoinWorkerThread)(Thread.currentThread());
550	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
551	<	w.helpJoinTask(this);
600	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
601	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
602	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
603	>	return tasks;
604		}
605	+	@SuppressWarnings("unchecked")
606	+	List<? extends ForkJoinTask<?>> ts =
607	+	(List<? extends ForkJoinTask<?>>) tasks;
608	+	Throwable ex = null;
609	+	int last = ts.size() - 1;
610	+	for (int i = last; i >= 0; --i) {
611	+	ForkJoinTask<?> t = ts.get(i);
612	+	if (t == null) {
613	+	if (ex == null)
614	+	ex = new NullPointerException();
615	+	}
616	+	else if (i != 0)
617	+	t.fork();
618	+	else {
619	+	t.quietlyInvoke();
620	+	if (ex == null)
621	+	ex = t.getException();
622	+	}
623	+	}
624	+	for (int i = 1; i <= last; ++i) {
625	+	ForkJoinTask<?> t = ts.get(i);
626	+	if (t != null) {
627	+	if (ex != null)
628	+	t.cancel(false);
629	+	else {
630	+	t.quietlyJoin();
631	+	if (ex == null)
632	+	ex = t.getException();
633	+	}
634	+	}
635	+	}
636	+	if (ex != null)
637	+	UNSAFE.throwException(ex);
638	+	return tasks;
639	+	}
640	+
641	+	/**
642	+	* Attempts to cancel execution of this task. This attempt will
643	+	* fail if the task has already completed, has already been
644	+	* cancelled, or could not be cancelled for some other reason. If
645	+	* successful, and this task has not started when cancel is
646	+	* called, execution of this task is suppressed, {@link
647	+	* #isCancelled} will report true, and {@link #join} will result
648	+	* in a {@code CancellationException} being thrown.
649	+	*
650	+	* <p>This method may be overridden in subclasses, but if so, must
651	+	* still ensure that these minimal properties hold. In particular,
652	+	* the {@code cancel} method itself must not throw exceptions.
653	+	*
654	+	* <p>This method is designed to be invoked by <em>other</em>
655	+	* tasks. To terminate the current task, you can just return or
656	+	* throw an unchecked exception from its computation method, or
657	+	* invoke {@link #completeExceptionally}.
658	+	*
659	+	* @param mayInterruptIfRunning this value is ignored in the
660	+	* default implementation because tasks are not
661	+	* cancelled via interruption
662	+	*
663	+	* @return {@code true} if this task is now cancelled
664	+	*/
665	+	public boolean cancel(boolean mayInterruptIfRunning) {
666	+	setCompletion(CANCELLED);
667	+	return (status & COMPLETION_MASK) == CANCELLED;
668		}
669
670		/**
671	<	* Performs this task and awaits its completion if necessary,
672	<	* without returning its result or throwing an exception. This
558	<	* method may be useful when processing collections of tasks when
559	<	* some have been cancelled or otherwise known to have aborted.
671	>	* Cancels, ignoring any exceptions it throws. Used during worker
672	>	* and pool shutdown.
673		*/
674	<	public final void quietlyInvoke() {
675	<	if (status >= 0 && !tryQuietlyInvoke())
676	<	quietlyJoin();
674	>	final void cancelIgnoringExceptions() {
675	>	try {
676	>	cancel(false);
677	>	} catch (Throwable ignore) {
678	>	}
679		}
680
681		/**
682	<	* Returns true if the computation performed by this task has
568	<	* completed (or has been cancelled).
569	<	* @return true if this computation has completed
682	>	* Cancels ignoring exceptions if worker is terminating
683		*/
684	+	private void cancelIfTerminating() {
685	+	Thread t = Thread.currentThread();
686	+	if ((t instanceof ForkJoinWorkerThread) &&
687	+	((ForkJoinWorkerThread) t).isTerminating()) {
688	+	try {
689	+	cancel(false);
690	+	} catch (Throwable ignore) {
691	+	}
692	+	}
693	+	}
694	+
695		public final boolean isDone() {
696		return status < 0;
697		}
698
575	–	/**
576	–	* Returns true if this task was cancelled.
577	–	* @return true if this task was cancelled
578	–	*/
699		public final boolean isCancelled() {
700		return (status & COMPLETION_MASK) == CANCELLED;
701		}
702
703		/**
704	<	* Returns true if this task threw an exception or was cancelled
705	<	* @return true if this task threw an exception or was cancelled
704	>	* Returns {@code true} if this task threw an exception or was cancelled.
705	>	*
706	>	* @return {@code true} if this task threw an exception or was cancelled
707		*/
708	<	public final boolean completedAbnormally() {
708	>	public final boolean isCompletedAbnormally() {
709		return (status & COMPLETION_MASK) < NORMAL;
710		}
711
712		/**
713	<	* Returns the exception thrown by the base computation, or a
714	<	* CancellationException if cancelled, or null if none or if the
715	<	* method has not yet completed.
716	<	* @return the exception, or null if none
713	>	* Returns {@code true} if this task completed without throwing an
714	>	* exception and was not cancelled.
715	>	*
716	>	* @return {@code true} if this task completed without throwing an
717	>	* exception and was not cancelled
718		*/
719	<	public final Throwable getException() {
720	<	int s = status & COMPLETION_MASK;
599	<	if (s >= NORMAL)
600	<	return null;
601	<	if (s == CANCELLED)
602	<	return new CancellationException();
603	<	return exceptionMap.get(this);
719	>	public final boolean isCompletedNormally() {
720	>	return (status & COMPLETION_MASK) == NORMAL;
721		}
722
723		/**
724	<	* Asserts that the results of this task's computation will not be
725	<	* used. If a cancellation occurs before this task is processed,
726	<	* then its <tt>compute</tt> method will not be executed,
610	<	* <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.
617	<	*
618	<	* <p>This method may be overridden in subclasses, but if so, must
619	<	* still ensure that these minimal properties hold. In particular,
620	<	* the cancel method itself must not throw exceptions.
621	<	*
622	<	* <p> This method is designed to be invoked by <em>other</em>
623	<	* tasks. To terminate the current task, you can just return or
624	<	* throw an unchecked exception from its computation method, or
625	<	* invoke <tt>completeExceptionally(someException)</tt>.
626	<	*
627	<	* @param mayInterruptIfRunning this value is ignored in the
628	<	* default implementation because tasks are not in general
629	<	* cancelled via interruption.
724	>	* Returns the exception thrown by the base computation, or a
725	>	* {@code CancellationException} if cancelled, or {@code null} if
726	>	* none or if the method has not yet completed.
727		*
728	<	* @return true if this task is now cancelled
728	>	* @return the exception, or {@code null} if none
729		*/
730	<	public boolean cancel(boolean mayInterruptIfRunning) {
731	<	setCompletion(CANCELLED);
732	<	return (status & COMPLETION_MASK) == CANCELLED;
730	>	public final Throwable getException() {
731	>	int s = status & COMPLETION_MASK;
732	>	return ((s >= NORMAL)    ? null :
733	>	(s == CANCELLED) ? new CancellationException() :
734	>	exceptionMap.get(this));
735		}
736
737		/**
738		* Completes this task abnormally, and if not already aborted or
739		* cancelled, causes it to throw the given exception upon
740	<	* <tt>join</tt> and related operations. This method may be used
740	>	* {@code join} and related operations. This method may be used
741		* to induce exceptions in asynchronous tasks, or to force
742	<	* completion of tasks that would not otherwise complete.  This
743	<	* method is overridable, but overridden versions must invoke
744	<	* <tt>super</tt> implementation to maintain guarantees.
745	<	* @param ex the exception to throw. If this exception is
746	<	* not a RuntimeException or Error, the actual exception thrown
747	<	* will be a RuntimeException with cause ex.
742	>	* completion of tasks that would not otherwise complete.  Its use
743	>	* in other situations is discouraged.  This method is
744	>	* overridable, but overridden versions must invoke {@code super}
745	>	* implementation to maintain guarantees.
746	>	*
747	>	* @param ex the exception to throw. If this exception is not a
748	>	* {@code RuntimeException} or {@code Error}, the actual exception
749	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
750		*/
751		public void completeExceptionally(Throwable ex) {
752		setDoneExceptionally((ex instanceof RuntimeException) ||
753	<	(ex instanceof Error)? ex :
753	>	(ex instanceof Error) ? ex :
754		new RuntimeException(ex));
755		}
756
757		/**
758		* Completes this task, and if not already aborted or cancelled,
759	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
759	>	* returning a {@code null} result upon {@code join} and related
760		* operations. This method may be used to provide results for
761		* asynchronous tasks, or to provide alternative handling for
762	<	* tasks that would not otherwise complete normally.
762	>	* tasks that would not otherwise complete normally. Its use in
763	>	* other situations is discouraged. This method is
764	>	* overridable, but overridden versions must invoke {@code super}
765	>	* implementation to maintain guarantees.
766		*
767	<	* @param value the result value for this task.
767	>	* @param value the result value for this task
768		*/
769		public void complete(V value) {
770		try {
771		setRawResult(value);
772	<	} catch(Throwable rex) {
772	>	} catch (Throwable rex) {
773		setDoneExceptionally(rex);
774		return;
775		}
776	<	setNormalCompletion();
776	>	setCompletion(NORMAL);
777	>	}
778	>
779	>	public final V get() throws InterruptedException, ExecutionException {
780	>	quietlyJoin();
781	>	return reportFutureResult();
782	>	}
783	>
784	>	public final V get(long timeout, TimeUnit unit)
785	>	throws InterruptedException, ExecutionException, TimeoutException {
786	>	long nanos = unit.toNanos(timeout);
787	>	Thread t = Thread.currentThread();
788	>	if (t instanceof ForkJoinWorkerThread) {
789	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
790	>	if (!w.unpushTask(this) || !tryExec())
791	>	timedAwaitDone(w, nanos);
792	>	}
793	>	else
794	>	externalTimedAwaitDone(nanos);
795	>	return reportTimedFutureResult();
796	>	}
797	>
798	>	/**
799	>	* Possibly executes other tasks until this task {@link #isDone is
800	>	* done}, then returns the result of the computation.  This method
801	>	* may be more efficient than {@code join}, but is only applicable
802	>	* when there are no potential dependencies between continuation
803	>	* of the current task and that of any other task that might be
804	>	* executed while helping. (This usually holds for pure
805	>	* divide-and-conquer tasks).
806	>	*
807	>	* <p>This method may be invoked only from within {@code
808	>	* ForkJoinTask} computations (as may be determined using method
809	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
810	>	* result in exceptions or errors, possibly including {@code
811	>	* ClassCastException}.
812	>	*
813	>	* @return the computed result
814	>	*/
815	>	public final V helpJoin() {
816	>	quietlyHelpJoin();
817	>	return reportResult();
818	>	}
819	>
820	>	/**
821	>	* Possibly executes other tasks until this task {@link #isDone is
822	>	* done}.  This method may be useful when processing collections
823	>	* of tasks when some have been cancelled or otherwise known to
824	>	* have aborted.
825	>	*
826	>	* <p>This method may be invoked only from within {@code
827	>	* ForkJoinTask} computations (as may be determined using method
828	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
829	>	* result in exceptions or errors, possibly including {@code
830	>	* ClassCastException}.
831	>	*/
832	>	public final void quietlyHelpJoin() {
833	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
834	>	if (!w.unpushTask(this) || !tryExec()) {
835	>	for (;;) {
836	>	ForkJoinTask<?> t;
837	>	if (status < 0)
838	>	return;
839	>	else if ((t = w.scanWhileJoining(this)) != null)
840	>	t.tryExec();
841	>	else if (status < 0)
842	>	return;
843	>	else if (w.pool.preBlockHelpingJoin(this)) {
844	>	while (status >= 0) { // variant of awaitDone
845	>	try {
846	>	synchronized(this) {
847	>	if (status >= 0)
848	>	wait();
849	>	else {
850	>	notifyAll();
851	>	break;
852	>	}
853	>	}
854	>	} catch (InterruptedException ie) {
855	>	cancelIfTerminating();
856	>	}
857	>	}
858	>	return;
859	>	}
860	>	}
861	>	}
862	>	}
863	>
864	>	/**
865	>	* Joins this task, without returning its result or throwing an
866	>	* exception. This method may be useful when processing
867	>	* collections of tasks when some have been cancelled or otherwise
868	>	* known to have aborted.
869	>	*/
870	>	public final void quietlyJoin() {
871	>	Thread t = Thread.currentThread();
872	>	if (t instanceof ForkJoinWorkerThread) {
873	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
874	>	if (!w.unpushTask(this) || !tryExec())
875	>	awaitDone(w);
876	>	}
877	>	else
878	>	externalAwaitDone();
879	>	}
880	>
881	>	/**
882	>	* Commences performing this task and awaits its completion if
883	>	* necessary, without returning its result or throwing an
884	>	* exception. This method may be useful when processing
885	>	* collections of tasks when some have been cancelled or otherwise
886	>	* known to have aborted.
887	>	*/
888	>	public final void quietlyInvoke() {
889	>	if (!tryExec())
890	>	quietlyJoin();
891	>	}
892	>
893	>	/**
894	>	* Possibly executes tasks until the pool hosting the current task
895	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
896	>	* be of use in designs in which many tasks are forked, but none
897	>	* are explicitly joined, instead executing them until all are
898	>	* processed.
899	>	*
900	>	* <p>This method may be invoked only from within {@code
901	>	* ForkJoinTask} computations (as may be determined using method
902	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
903	>	* result in exceptions or errors, possibly including {@code
904	>	* ClassCastException}.
905	>	*/
906	>	public static void helpQuiesce() {
907	>	((ForkJoinWorkerThread) Thread.currentThread())
908	>	.helpQuiescePool();
909		}
910
911		/**
912		* Resets the internal bookkeeping state of this task, allowing a
913	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
913	>	* subsequent {@code fork}. This method allows repeated reuse of
914		* this task, but only if reuse occurs when this task has either
915		* never been forked, or has been forked, then completed and all
916		* outstanding joins of this task have also completed. Effects
917	<	* under any other usage conditions are not guaranteed, and are
918	<	* almost surely wrong. This method may be useful when executing
917	>	* under any other usage conditions are not guaranteed.
918	>	* This method may be useful when executing
919		* pre-constructed trees of subtasks in loops.
920		*/
921		public void reinitialize() {
#	Line 689 | Line 925 | public abstract class ForkJoinTask<V> im
925		}
926
927		/**
928	<	* Tries to unschedule this task for execution. This method will
929	<	* typically succeed if this task is the next task that would be
930	<	* executed by the current thread, and will typically fail (return
931	<	* false) otherwise. This method may be useful when arranging
932	<	* faster local processing of tasks that could have been, but were
697	<	* not, stolen.
698	<	* @return true if unforked
699	<	*/
700	<	public boolean tryUnfork() {
701	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
702	<	}
703	<
704	<	/**
705	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
706	<	* of them or an exception is encountered. This method may be
707	<	* invoked only from within other ForkJoinTask
708	<	* computations. Attempts to invoke in other contexts result in
709	<	* exceptions or errors including ClassCastException.
710	<	* @param t1 one task
711	<	* @param t2 the other task
712	<	* @throws NullPointerException if t1 or t2 are null
713	<	* @throws RuntimeException or Error if either task did so.
928	>	* Returns the pool hosting the current task execution, or null
929	>	* if this task is executing outside of any ForkJoinPool.
930	>	*
931	>	* @see #inForkJoinPool
932	>	* @return the pool, or {@code null} if none
933		*/
934	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
935	<	t2.fork();
936	<	t1.invoke();
937	<	t2.join();
934	>	public static ForkJoinPool getPool() {
935	>	Thread t = Thread.currentThread();
936	>	return (t instanceof ForkJoinWorkerThread) ?
937	>	((ForkJoinWorkerThread) t).pool : null;
938		}
939
940		/**
941	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
942	<	* all of them. If any task encounters an exception, others may be
943	<	* cancelled.  This method may be invoked only from within other
944	<	* ForkJoinTask computations. Attempts to invoke in other contexts
945	<	* result in exceptions or errors including ClassCastException.
727	<	* @param tasks the array of tasks
728	<	* @throws NullPointerException if tasks or any element are null.
729	<	* @throws RuntimeException or Error if any task did so.
941	>	* Returns {@code true} if the current thread is executing as a
942	>	* ForkJoinPool computation.
943	>	*
944	>	* @return {@code true} if the current thread is executing as a
945	>	* ForkJoinPool computation, or false otherwise
946		*/
947	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
948	<	Throwable ex = null;
733	<	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);
947	>	public static boolean inForkJoinPool() {
948	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
949		}
950
951		/**
952	<	* Forks all tasks in the collection, returning when
953	<	* <tt>isDone</tt> holds for all of them. If any task encounters
954	<	* an exception, others may be cancelled.  This method may be
955	<	* invoked only from within other ForkJoinTask
956	<	* computations. Attempts to invoke in other contexts result in
957	<	* exceptions or errors including ClassCastException.
958	<	* @param tasks the collection of tasks
959	<	* @throws NullPointerException if tasks or any element are null.
960	<	* @throws RuntimeException or Error if any task did so.
952	>	* Tries to unschedule this task for execution. This method will
953	>	* typically succeed if this task is the most recently forked task
954	>	* by the current thread, and has not commenced executing in
955	>	* another thread.  This method may be useful when arranging
956	>	* alternative local processing of tasks that could have been, but
957	>	* were not, stolen.
958	>	*
959	>	* <p>This method may be invoked only from within {@code
960	>	* ForkJoinTask} computations (as may be determined using method
961	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
962	>	* result in exceptions or errors, possibly including {@code
963	>	* ClassCastException}.
964	>	*
965	>	* @return {@code true} if unforked
966		*/
967	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
968	<	if (!(tasks instanceof List)) {
969	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
778	<	return;
779	<	}
780	<	List<? extends ForkJoinTask<?>> ts =
781	<	(List<? extends ForkJoinTask<?>>)tasks;
782	<	Throwable ex = null;
783	<	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	<	}
797	<	}
798	<	for (int i = 1; i <= last; ++i) {
799	<	ForkJoinTask<?> t = ts.get(i);
800	<	if (t != null) {
801	<	if (ex != null)
802	<	t.cancel(false);
803	<	else {
804	<	t.quietlyJoin();
805	<	if (ex == null)
806	<	ex = t.getException();
807	<	}
808	<	}
809	<	}
810	<	if (ex != null)
811	<	rethrowException(ex);
967	>	public boolean tryUnfork() {
968	>	return ((ForkJoinWorkerThread) Thread.currentThread())
969	>	.unpushTask(this);
970		}
971
972		/**
973	<	* Possibly executes tasks until the pool hosting the current task
974	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
975	<	* designs in which many tasks are forked, but none are explicitly
976	<	* joined, instead executing them until all are processed.
973	>	* Returns an estimate of the number of tasks that have been
974	>	* forked by the current worker thread but not yet executed. This
975	>	* value may be useful for heuristic decisions about whether to
976	>	* fork other tasks.
977	>	*
978	>	* <p>This method may be invoked only from within {@code
979	>	* ForkJoinTask} computations (as may be determined using method
980	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
981	>	* result in exceptions or errors, possibly including {@code
982	>	* ClassCastException}.
983	>	*
984	>	* @return the number of tasks
985		*/
986	<	public static void helpQuiesce() {
987	<	((ForkJoinWorkerThread)(Thread.currentThread())).
988	<	helpQuiescePool();
986	>	public static int getQueuedTaskCount() {
987	>	return ((ForkJoinWorkerThread) Thread.currentThread())
988	>	.getQueueSize();
989		}
990
991		/**
992	<	* Returns a estimate of how many more locally queued tasks are
992	>	* Returns an estimate of how many more locally queued tasks are
993		* held by the current worker thread than there are other worker
994	<	* threads that might want to steal them.  This value may be
995	<	* useful for heuristic decisions about whether to fork other
996	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
997	<	* worker should aim to maintain a small constant surplus (for
998	<	* example, 3) of tasks, and to process computations locally if
999	<	* this threshold is exceeded.
994	>	* threads that might steal them.  This value may be useful for
995	>	* heuristic decisions about whether to fork other tasks. In many
996	>	* usages of ForkJoinTasks, at steady state, each worker should
997	>	* aim to maintain a small constant surplus (for example, 3) of
998	>	* tasks, and to process computations locally if this threshold is
999	>	* exceeded.
1000	>	*
1001	>	* <p>This method may be invoked only from within {@code
1002	>	* ForkJoinTask} computations (as may be determined using method
1003	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1004	>	* result in exceptions or errors, possibly including {@code
1005	>	* ClassCastException}.
1006	>	*
1007		* @return the surplus number of tasks, which may be negative
1008		*/
1009	<	public static int surplus() {
1010	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
1009	>	public static int getSurplusQueuedTaskCount() {
1010	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1011		.getEstimatedSurplusTaskCount();
1012		}
1013
1014	<	// Extension kit
1014	>	// Extension methods
1015
1016		/**
1017	<	* Returns the result that would be returned by <tt>join</tt>, or
1018	<	* null if this task is not known to have been completed.  This
1019	<	* method is designed to aid debugging, as well as to support
1020	<	* extensions. Its use in any other context is discouraged.
1017	>	* Returns the result that would be returned by {@link #join}, even
1018	>	* if this task completed abnormally, or {@code null} if this task
1019	>	* is not known to have been completed.  This method is designed
1020	>	* to aid debugging, as well as to support extensions. Its use in
1021	>	* any other context is discouraged.
1022		*
1023	<	* @return the result, or null if not completed.
1023	>	* @return the result, or {@code null} if not completed
1024		*/
1025		public abstract V getRawResult();
1026
#	Line 865 | Line 1039 | public abstract class ForkJoinTask<V> im
1039		* called otherwise. The return value controls whether this task
1040		* is considered to be done normally. It may return false in
1041		* asynchronous actions that require explicit invocations of
1042	<	* <tt>complete</tt> to become joinable. It may throw exceptions
1043	<	* to indicate abnormal exit.
1044	<	* @return true if completed normally
1045	<	* @throws Error or RuntimeException if encountered during computation
1042	>	* {@link #complete} to become joinable. It may also throw an
1043	>	* (unchecked) exception to indicate abnormal exit.
1044	>	*
1045	>	* @return {@code true} if completed normally
1046		*/
1047		protected abstract boolean exec();
1048
1049	+	/**
1050	+	* Returns, but does not unschedule or execute, a task queued by
1051	+	* the current thread but not yet executed, if one is immediately
1052	+	* available. There is no guarantee that this task will actually
1053	+	* be polled or executed next. Conversely, this method may return
1054	+	* null even if a task exists but cannot be accessed without
1055	+	* contention with other threads.  This method is designed
1056	+	* primarily to support extensions, and is unlikely to be useful
1057	+	* otherwise.
1058	+	*
1059	+	* <p>This method may be invoked only from within {@code
1060	+	* ForkJoinTask} computations (as may be determined using method
1061	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1062	+	* result in exceptions or errors, possibly including {@code
1063	+	* ClassCastException}.
1064	+	*
1065	+	* @return the next task, or {@code null} if none are available
1066	+	*/
1067	+	protected static ForkJoinTask<?> peekNextLocalTask() {
1068	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1069	+	.peekTask();
1070	+	}
1071	+
1072	+	/**
1073	+	* Unschedules and returns, without executing, the next task
1074	+	* queued by the current thread but not yet executed.  This method
1075	+	* is designed primarily to support extensions, and is unlikely to
1076	+	* be useful otherwise.
1077	+	*
1078	+	* <p>This method may be invoked only from within {@code
1079	+	* ForkJoinTask} computations (as may be determined using method
1080	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1081	+	* result in exceptions or errors, possibly including {@code
1082	+	* ClassCastException}.
1083	+	*
1084	+	* @return the next task, or {@code null} if none are available
1085	+	*/
1086	+	protected static ForkJoinTask<?> pollNextLocalTask() {
1087	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1088	+	.pollLocalTask();
1089	+	}
1090	+
1091	+	/**
1092	+	* Unschedules and returns, without executing, the next task
1093	+	* queued by the current thread but not yet executed, if one is
1094	+	* available, or if not available, a task that was forked by some
1095	+	* other thread, if available. Availability may be transient, so a
1096	+	* {@code null} result does not necessarily imply quiescence
1097	+	* of the pool this task is operating in.  This method is designed
1098	+	* primarily to support extensions, and is unlikely to be useful
1099	+	* otherwise.
1100	+	*
1101	+	* <p>This method may be invoked only from within {@code
1102	+	* ForkJoinTask} computations (as may be determined using method
1103	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1104	+	* result in exceptions or errors, possibly including {@code
1105	+	* ClassCastException}.
1106	+	*
1107	+	* @return a task, or {@code null} if none are available
1108	+	*/
1109	+	protected static ForkJoinTask<?> pollTask() {
1110	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1111	+	.pollTask();
1112	+	}
1113	+
1114	+	/**
1115	+	* Adaptor for Runnables. This implements RunnableFuture
1116	+	* to be compliant with AbstractExecutorService constraints
1117	+	* when used in ForkJoinPool.
1118	+	*/
1119	+	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1120	+	implements RunnableFuture<T> {
1121	+	final Runnable runnable;
1122	+	final T resultOnCompletion;
1123	+	T result;
1124	+	AdaptedRunnable(Runnable runnable, T result) {
1125	+	if (runnable == null) throw new NullPointerException();
1126	+	this.runnable = runnable;
1127	+	this.resultOnCompletion = result;
1128	+	}
1129	+	public T getRawResult() { return result; }
1130	+	public void setRawResult(T v) { result = v; }
1131	+	public boolean exec() {
1132	+	runnable.run();
1133	+	result = resultOnCompletion;
1134	+	return true;
1135	+	}
1136	+	public void run() { invoke(); }
1137	+	private static final long serialVersionUID = 5232453952276885070L;
1138	+	}
1139	+
1140	+	/**
1141	+	* Adaptor for Callables
1142	+	*/
1143	+	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1144	+	implements RunnableFuture<T> {
1145	+	final Callable<? extends T> callable;
1146	+	T result;
1147	+	AdaptedCallable(Callable<? extends T> callable) {
1148	+	if (callable == null) throw new NullPointerException();
1149	+	this.callable = callable;
1150	+	}
1151	+	public T getRawResult() { return result; }
1152	+	public void setRawResult(T v) { result = v; }
1153	+	public boolean exec() {
1154	+	try {
1155	+	result = callable.call();
1156	+	return true;
1157	+	} catch (Error err) {
1158	+	throw err;
1159	+	} catch (RuntimeException rex) {
1160	+	throw rex;
1161	+	} catch (Exception ex) {
1162	+	throw new RuntimeException(ex);
1163	+	}
1164	+	}
1165	+	public void run() { invoke(); }
1166	+	private static final long serialVersionUID = 2838392045355241008L;
1167	+	}
1168	+
1169	+	/**
1170	+	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1171	+	* method of the given {@code Runnable} as its action, and returns
1172	+	* a null result upon {@link #join}.
1173	+	*
1174	+	* @param runnable the runnable action
1175	+	* @return the task
1176	+	*/
1177	+	public static ForkJoinTask<?> adapt(Runnable runnable) {
1178	+	return new AdaptedRunnable<Void>(runnable, null);
1179	+	}
1180	+
1181	+	/**
1182	+	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1183	+	* method of the given {@code Runnable} as its action, and returns
1184	+	* the given result upon {@link #join}.
1185	+	*
1186	+	* @param runnable the runnable action
1187	+	* @param result the result upon completion
1188	+	* @return the task
1189	+	*/
1190	+	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1191	+	return new AdaptedRunnable<T>(runnable, result);
1192	+	}
1193	+
1194	+	/**
1195	+	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1196	+	* method of the given {@code Callable} as its action, and returns
1197	+	* its result upon {@link #join}, translating any checked exceptions
1198	+	* encountered into {@code RuntimeException}.
1199	+	*
1200	+	* @param callable the callable action
1201	+	* @return the task
1202	+	*/
1203	+	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1204	+	return new AdaptedCallable<T>(callable);
1205	+	}
1206	+
1207		// Serialization support
1208
1209		private static final long serialVersionUID = -7721805057305804111L;
1210
1211		/**
1212	<	* Save the state to a stream.
1212	>	* Saves the state to a stream.
1213		*
1214		* @serialData the current run status and the exception thrown
1215	<	* during execution, or null if none.
1215	>	* during execution, or {@code null} if none
1216		* @param s the stream
1217		*/
1218		private void writeObject(java.io.ObjectOutputStream s)
#	Line 890 | Line 1222 | public abstract class ForkJoinTask<V> im
1222		}
1223
1224		/**
1225	<	* Reconstitute the instance from a stream.
1225	>	* Reconstitutes the instance from a stream.
1226	>	*
1227		* @param s the stream
1228		*/
1229		private void readObject(java.io.ObjectInputStream s)
1230		throws java.io.IOException, ClassNotFoundException {
1231		s.defaultReadObject();
1232	<	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1232	>	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1233	>	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1234		Object ex = s.readObject();
1235		if (ex != null)
1236	<	setDoneExceptionally((Throwable)ex);
1236	>	setDoneExceptionally((Throwable) ex);
1237		}
1238
1239	<	// Temporary Unsafe mechanics for preliminary release
1239	>	// Unsafe mechanics
1240
1241	<	static final Unsafe _unsafe;
1242	<	static final long statusOffset;
1241	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1242	>	private static final long statusOffset =
1243	>	objectFieldOffset("status", ForkJoinTask.class);
1244
1245	<	static {
1245	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1246		try {
1247	<	if (ForkJoinTask.class.getClassLoader() != null) {
1248	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1249	<	f.setAccessible(true);
1250	<	_unsafe = (Unsafe)f.get(null);
1251	<	}
1252	<	else
1253	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
920	<	(ForkJoinTask.class.getDeclaredField("status"));
921	<	} catch (Exception ex) { throw new Error(ex); }
1247	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1248	>	} catch (NoSuchFieldException e) {
1249	>	// Convert Exception to corresponding Error
1250	>	NoSuchFieldError error = new NoSuchFieldError(field);
1251	>	error.initCause(e);
1252	>	throw error;
1253	>	}
1254		}
1255
1256	+	/**
1257	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1258	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1259	+	* into a jdk.
1260	+	*
1261	+	* @return a sun.misc.Unsafe
1262	+	*/
1263	+	private static sun.misc.Unsafe getUnsafe() {
1264	+	try {
1265	+	return sun.misc.Unsafe.getUnsafe();
1266	+	} catch (SecurityException se) {
1267	+	try {
1268	+	return java.security.AccessController.doPrivileged
1269	+	(new java.security
1270	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1271	+	public sun.misc.Unsafe run() throws Exception {
1272	+	java.lang.reflect.Field f = sun.misc
1273	+	.Unsafe.class.getDeclaredField("theUnsafe");
1274	+	f.setAccessible(true);
1275	+	return (sun.misc.Unsafe) f.get(null);
1276	+	}});
1277	+	} catch (java.security.PrivilegedActionException e) {
1278	+	throw new RuntimeException("Could not initialize intrinsics",
1279	+	e.getCause());
1280	+	}
1281	+	}
1282	+	}
1283		}

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