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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 1.79 by jsr166, Fri Jun 10 18:10:53 2011 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3		* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7		package jsr166y;
8	+
9		import java.io.Serializable;
10	<	import java.util.*;
11	<	import java.util.concurrent.*;
12	<	import java.util.concurrent.atomic.*;
13	<	import sun.misc.Unsafe;
14	<	import java.lang.reflect.*;
10	>	import java.util.Collection;
11	>	import java.util.List;
12	>	import java.util.RandomAccess;
13	>	import java.lang.ref.WeakReference;
14	>	import java.lang.ref.ReferenceQueue;
15	>	import java.util.concurrent.Callable;
16	>	import java.util.concurrent.CancellationException;
17	>	import java.util.concurrent.ExecutionException;
18	>	import java.util.concurrent.Future;
19	>	import java.util.concurrent.RejectedExecutionException;
20	>	import java.util.concurrent.RunnableFuture;
21	>	import java.util.concurrent.TimeUnit;
22	>	import java.util.concurrent.TimeoutException;
23	>	import java.util.concurrent.locks.ReentrantLock;
24	>	import java.lang.reflect.Constructor;
25
26		/**
27	<	* Abstract base class for tasks that run within a ForkJoinPool.  A
28	<	* ForkJoinTask is a thread-like entity that is much lighter weight
29	<	* than a normal thread.  Huge numbers of tasks and subtasks may be
30	<	* hosted by a small number of actual threads in a ForkJoinPool,
31	<	* at the price of some usage limitations.
32	<	*
33	<	* <p> ForkJoinTasks are forms of <tt>Futures</tt> supporting a
34	<	* limited range of use.  The "lightness" of ForkJoinTasks is due to a
35	<	* set of restrictions (that are only partially statically
36	<	* enforceable) reflecting their intended use as computational tasks
37	<	* calculating pure functions or operating on purely isolated objects.
38	<	* The primary coordination mechanisms supported for ForkJoinTasks are
39	<	* <tt>fork</tt>, that arranges asynchronous execution, and
40	<	* <tt>join</tt>, that doesn't proceed until the task's result has
41	<	* been computed. (Cancellation is also supported).  The computation
42	<	* defined in the <tt>compute</tt> method should avoid
43	<	* <tt>synchronized</tt> methods or blocks, and should minimize
44	<	* blocking synchronization apart from joining other tasks or using
45	<	* synchronizers such as Phasers that are advertised to cooperate with
46	<	* fork/join scheduling. Tasks should also not perform blocking IO,
47	<	* and should ideally access variables that are completely independent
48	<	* of those accessed by other running tasks. Minor breaches of these
49	<	* restrictions, for example using shared output streams, may be
50	<	* tolerable in practice, but frequent use may result in poor
51	<	* performance, and the potential to indefinitely stall if the number
52	<	* of threads not waiting for external synchronization becomes
53	<	* exhausted. This usage restriction is in part enforced by not
54	<	* permitting checked exceptions such as IOExceptions to be
55	<	* thrown. However, computations may still encounter unchecked
56	<	* exceptions, that are rethrown to callers attempting join
57	<	* them. These exceptions may additionally include
58	<	* RejectedExecutionExceptions stemming from internal resource
59	<	* exhaustion such as failure to allocate internal task queues.
60	<	*
61	<	* <p> The <tt>ForkJoinTask</tt> class is not usually directly
62	<	* subclassed.  Instead, you subclass one of the abstract classes that
63	<	* support different styles of fork/join processing.  Normally, a
64	<	* concrete ForkJoinTask subclass declares fields comprising its
65	<	* parameters, established in a constructor, and then defines a
66	<	* <tt>compute</tt> method that somehow uses the control methods
67	<	* supplied by this base class. While these methods have
68	<	* <tt>public</tt> access, some of them may only be called from within
69	<	* other ForkJoinTasks. Attempts to invoke them in other contexts
70	<	* result in exceptions or errors including ClassCastException.  The
71	<	* only way to invoke a "main" driver task is to submit it to a
72	<	* ForkJoinPool. Once started, this will usually in turn start other
73	<	* subtasks.
74	<	*
75	<	* <p>Most base support methods are <tt>final</tt> because their
76	<	* implementations are intrinsically tied to the underlying
77	<	* lightweight task scheduling framework, and so cannot be overridden.
78	<	* Developers creating new basic styles of fork/join processing should
79	<	* minimally implement protected methods <tt>exec</tt>,
80	<	* <tt>setRawResult</tt>, and <tt>getRawResult</tt>, while also
81	<	* introducing an abstract computational method that can be
82	<	* implemented in its subclasses. To support such extensions,
83	<	* instances of ForkJoinTasks maintain an atomically updated
84	<	* <tt>short</tt> representing user-defined control state.  Control
85	<	* state is guaranteed initially to be zero, and to be negative upon
86	<	* completion, but may otherwise be used for any other control
87	<	* purposes, such as maintaining join counts.  The {@link
88	<	* ForkJoinWorkerThread} class supports additional inspection and
89	<	* tuning methods that can be useful when developing extensions.
27	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
28	>	* A {@code ForkJoinTask} is a thread-like entity that is much
29	>	* lighter weight than a normal thread.  Huge numbers of tasks and
30	>	* subtasks may be hosted by a small number of actual threads in a
31	>	* ForkJoinPool, at the price of some usage limitations.
32	>	*
33	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
34	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
35	>	* start other subtasks.  As indicated by the name of this class,
36	>	* many programs using {@code ForkJoinTask} employ only methods
37	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
38	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
39	>	* provides a number of other methods that can come into play in
40	>	* advanced usages, as well as extension mechanics that allow
41	>	* support of new forms of fork/join processing.
42	>	*
43	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
44	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
45	>	* restrictions (that are only partially statically enforceable)
46	>	* reflecting their intended use as computational tasks calculating
47	>	* pure functions or operating on purely isolated objects.  The
48	>	* primary coordination mechanisms are {@link #fork}, that arranges
49	>	* asynchronous execution, and {@link #join}, that doesn't proceed
50	>	* until the task's result has been computed.  Computations should
51	>	* avoid {@code synchronized} methods or blocks, and should minimize
52	>	* other blocking synchronization apart from joining other tasks or
53	>	* using synchronizers such as Phasers that are advertised to
54	>	* cooperate with fork/join scheduling. Tasks should also not perform
55	>	* blocking IO, and should ideally access variables that are
56	>	* completely independent of those accessed by other running
57	>	* tasks. Minor breaches of these restrictions, for example using
58	>	* shared output streams, may be tolerable in practice, but frequent
59	>	* use may result in poor performance, and the potential to
60	>	* indefinitely stall if the number of threads not waiting for IO or
61	>	* other external synchronization becomes exhausted. This usage
62	>	* restriction is in part enforced by not permitting checked
63	>	* exceptions such as {@code IOExceptions} to be thrown. However,
64	>	* computations may still encounter unchecked exceptions, that are
65	>	* rethrown to callers attempting to join them. These exceptions may
66	>	* additionally include {@link RejectedExecutionException} stemming
67	>	* from internal resource exhaustion, such as failure to allocate
68	>	* internal task queues. Rethrown exceptions behave in the same way as
69	>	* regular exceptions, but, when possible, contain stack traces (as
70	>	* displayed for example using {@code ex.printStackTrace()}) of both
71	>	* the thread that initiated the computation as well as the thread
72	>	* actually encountering the exception; minimally only the latter.
73	>	*
74	>	* <p>The primary method for awaiting completion and extracting
75	>	* results of a task is {@link #join}, but there are several variants:
76	>	* The {@link Future#get} methods support interruptible and/or timed
77	>	* waits for completion and report results using {@code Future}
78	>	* conventions. Method {@link #invoke} is semantically
79	>	* equivalent to {@code fork(); join()} but always attempts to begin
80	>	* execution in the current thread. The "<em>quiet</em>" forms of
81	>	* these methods do not extract results or report exceptions. These
82	>	* may be useful when a set of tasks are being executed, and you need
83	>	* to delay processing of results or exceptions until all complete.
84	>	* Method {@code invokeAll} (available in multiple versions)
85	>	* performs the most common form of parallel invocation: forking a set
86	>	* of tasks and joining them all.
87	>	*
88	>	* <p>The execution status of tasks may be queried at several levels
89	>	* of detail: {@link #isDone} is true if a task completed in any way
90	>	* (including the case where a task was cancelled without executing);
91	>	* {@link #isCompletedNormally} is true if a task completed without
92	>	* cancellation or encountering an exception; {@link #isCancelled} is
93	>	* true if the task was cancelled (in which case {@link #getException}
94	>	* returns a {@link java.util.concurrent.CancellationException}); and
95	>	* {@link #isCompletedAbnormally} is true if a task was either
96	>	* cancelled or encountered an exception, in which case {@link
97	>	* #getException} will return either the encountered exception or
98	>	* {@link java.util.concurrent.CancellationException}.
99	>	*
100	>	* <p>The ForkJoinTask class is not usually directly subclassed.
101	>	* Instead, you subclass one of the abstract classes that support a
102	>	* particular style of fork/join processing, typically {@link
103	>	* RecursiveAction} for computations that do not return results, or
104	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
105	>	* ForkJoinTask subclass declares fields comprising its parameters,
106	>	* established in a constructor, and then defines a {@code compute}
107	>	* method that somehow uses the control methods supplied by this base
108	>	* class. While these methods have {@code public} access (to allow
109	>	* instances of different task subclasses to call each other's
110	>	* methods), some of them may only be called from within other
111	>	* ForkJoinTasks (as may be determined using method {@link
112	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
113	>	* result in exceptions or errors, possibly including
114	>	* {@code ClassCastException}.
115	>	*
116	>	* <p>Method {@link #join} and its variants are appropriate for use
117	>	* only when completion dependencies are acyclic; that is, the
118	>	* parallel computation can be described as a directed acyclic graph
119	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
120	>	* tasks cyclically wait for each other.  However, this framework
121	>	* supports other methods and techniques (for example the use of
122	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
123	>	* may be of use in constructing custom subclasses for problems that
124	>	* are not statically structured as DAGs.
125	>	*
126	>	* <p>Most base support methods are {@code final}, to prevent
127	>	* overriding of implementations that are intrinsically tied to the
128	>	* underlying lightweight task scheduling framework.  Developers
129	>	* creating new basic styles of fork/join processing should minimally
130	>	* implement {@code protected} methods {@link #exec}, {@link
131	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
132	>	* an abstract computational method that can be implemented in its
133	>	* subclasses, possibly relying on other {@code protected} methods
134	>	* provided by this class.
135		*
136		* <p>ForkJoinTasks should perform relatively small amounts of
137	<	* computations, othewise splitting into smaller tasks. As a very
138	<	* rough rule of thumb, a task should perform more than 100 and less
139	<	* than 10000 basic computational steps. If tasks are too big, then
140	<	* parellelism cannot improve throughput. If too small, then memory
141	<	* and internal task maintenance overhead may overwhelm processing.
142	<	*
143	<	* <p>ForkJoinTasks are <tt>Serializable</tt>, which enables them to
144	<	* be used in extensions such as remote execution frameworks. However,
145	<	* it is in general safe to serialize tasks only before or after, but
146	<	* not during execution. Serialization is not relied on during
147	<	* execution itself.
137	>	* computation. Large tasks should be split into smaller subtasks,
138	>	* usually via recursive decomposition. As a very rough rule of thumb,
139	>	* a task should perform more than 100 and less than 10000 basic
140	>	* computational steps, and should avoid indefinite looping. If tasks
141	>	* are too big, then parallelism cannot improve throughput. If too
142	>	* small, then memory and internal task maintenance overhead may
143	>	* overwhelm processing.
144	>	*
145	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
146	>	* and {@link Callable}, that may be of use when mixing execution of
147	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
148	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
149	>	*
150	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
151	>	* used in extensions such as remote execution frameworks. It is
152	>	* sensible to serialize tasks only before or after, but not during,
153	>	* execution. Serialization is not relied on during execution itself.
154	>	*
155	>	* @since 1.7
156	>	* @author Doug Lea
157		*/
158		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
94	–	/**
95	–	* Status field holding all run status. We pack this into a single
96	–	* int both to minimize footprint overhead and to ensure atomicity
97	–	* (updates are via CAS).
98	–	*
99	–	* Status is initially zero, and takes on nonnegative values until
100	–	* completed, upon which status holds COMPLETED. CANCELLED, or
101	–	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
102	–	* blocking waits by other threads have SIGNAL_MASK bits set --
103	–	* bit 15 for external (nonFJ) waits, and the rest a count of
104	–	* waiting FJ threads.  (This representation relies on
105	–	* ForkJoinPool max thread limits). Completion of a stolen task
106	–	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
107	–	* though suboptimal for some purposes, we use basic builtin
108	–	* wait/notify to take advantage of "monitor inflation" in JVMs
109	–	* that we would otherwise need to emulate to avoid adding further
110	–	* per-task bookkeeping overhead. Note that bits 16-28 are
111	–	* currently unused. Also value 0x80000000 is available as spare
112	–	* completion value.
113	–	*/
114	–	volatile int status; // accessed directy by pool and workers
115	–
116	–	static final int COMPLETION_MASK      = 0xe0000000;
117	–	static final int NORMAL               = 0xe0000000; // == mask
118	–	static final int CANCELLED            = 0xc0000000;
119	–	static final int EXCEPTIONAL          = 0xa0000000;
120	–	static final int SIGNAL_MASK          = 0x0000ffff;
121	–	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
122	–	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
123	–
124	–	/**
125	–	* Table of exceptions thrown by tasks, to enable reporting by
126	–	* callers. Because exceptions are rare, we don't directly keep
127	–	* them with task objects, but instead us a weak ref table.  Note
128	–	* that cancellation exceptions don't appear in the table, but are
129	–	* instead recorded as status values.
130	–	* Todo: Use ConcurrentReferenceHashMap
131	–	*/
132	–	static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
133	–	Collections.synchronizedMap
134	–	(new WeakHashMap<ForkJoinTask<?>, Throwable>());
135	–
136	–	// within-package utilities
137	–
138	–	/**
139	–	* Get current worker thread, or null if not a worker thread
140	–	*/
141	–	static ForkJoinWorkerThread getWorker() {
142	–	Thread t = Thread.currentThread();
143	–	return ((t instanceof ForkJoinWorkerThread)?
144	–	(ForkJoinWorkerThread)t : null);
145	–	}
146	–
147	–	/**
148	–	* Get pool of current worker thread, or null if not a worker thread
149	–	*/
150	–	static ForkJoinPool getWorkerPool() {
151	–	Thread t = Thread.currentThread();
152	–	return ((t instanceof ForkJoinWorkerThread)?
153	–	((ForkJoinWorkerThread)t).pool : null);
154	–	}
155	–
156	–	final boolean casStatus(int cmp, int val) {
157	–	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
158	–	}
159	–
160	–	/**
161	–	* Workaround for not being able to rethrow unchecked exceptions.
162	–	*/
163	–	static void rethrowException(Throwable ex) {
164	–	if (ex != null)
165	–	_unsafe.throwException(ex);
166	–	}
159
160	<	// Setting completion status
160	>	/*
161	>	* See the internal documentation of class ForkJoinPool for a
162	>	* general implementation overview.  ForkJoinTasks are mainly
163	>	* responsible for maintaining their "status" field amidst relays
164	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
165	>	* methods of this class are more-or-less layered into (1) basic
166	>	* status maintenance (2) execution and awaiting completion (3)
167	>	* user-level methods that additionally report results. This is
168	>	* sometimes hard to see because this file orders exported methods
169	>	* in a way that flows well in javadocs.
170	>	*/
171	>
172	>	/*
173	>	* The status field holds run control status bits packed into a
174	>	* single int to minimize footprint and to ensure atomicity (via
175	>	* CAS).  Status is initially zero, and takes on nonnegative
176	>	* values until completed, upon which status holds value
177	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
178	>	* waits by other threads have the SIGNAL bit set.  Completion of
179	>	* a stolen task with SIGNAL set awakens any waiters via
180	>	* notifyAll. Even though suboptimal for some purposes, we use
181	>	* basic builtin wait/notify to take advantage of "monitor
182	>	* inflation" in JVMs that we would otherwise need to emulate to
183	>	* avoid adding further per-task bookkeeping overhead.  We want
184	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
185	>	* techniques, so use some odd coding idioms that tend to avoid
186	>	* them.
187	>	*/
188	>
189	>	/** The run status of this task */
190	>	volatile int status; // accessed directly by pool and workers
191	>	private static final int NORMAL      = -1;
192	>	private static final int CANCELLED   = -2;
193	>	private static final int EXCEPTIONAL = -3;
194	>	private static final int SIGNAL      =  1;
195
196		/**
197	<	* Mark completion and wake up threads waiting to join this task.
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 completion status on exit
202		*/
203	<	final void setCompletion(int completion) {
204	<	ForkJoinPool pool = getWorkerPool();
205	<	if (pool != null) {
206	<	int s; // Clear signal bits while setting completion status
207	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
208	<
209	<	if ((s & SIGNAL_MASK) != 0) {
210	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
182	<	pool.updateRunningCount(s);
183	<	synchronized(this) { notifyAll(); }
203	>	private int setCompletion(int completion) {
204	>	for (int s;;) {
205	>	if ((s = status) < 0)
206	>	return s;
207	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
208	>	if (s != 0)
209	>	synchronized (this) { notifyAll(); }
210	>	return completion;
211		}
212		}
186	–	else
187	–	externallySetCompletion(completion);
213		}
214
215		/**
216	<	* Version of setCompletion for non-FJ threads.  Leaves signal
217	<	* bits for unblocked threads to adjust, and always notifies.
216	>	* Tries to block a worker thread until completed or timed out.
217	>	* Uses Object.wait time argument conventions.
218	>	* May fail on contention or interrupt.
219	>	*
220	>	* @param millis if > 0, wait time.
221		*/
222	<	private void externallySetCompletion(int completion) {
222	>	final void tryAwaitDone(long millis) {
223		int s;
196	–	do;while ((s = status) >= 0 &&
197	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
198	–	synchronized(this) { notifyAll(); }
199	–	}
200	–
201	–	/**
202	–	* Sets status to indicate normal completion
203	–	*/
204	–	final void setNormalCompletion() {
205	–	// Try typical fast case -- single CAS, no signal, not already done.
206	–	// Manually expand casStatus to improve chances of inlining it
207	–	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
208	–	setCompletion(NORMAL);
209	–	}
210	–
211	–	// internal waiting and notification
212	–
213	–	/**
214	–	* Performs the actual monitor wait for awaitDone
215	–	*/
216	–	private void doAwaitDone() {
217	–	// Minimize lock bias and in/de-flation effects by maximizing
218	–	// chances of waiting inside sync
224		try {
225	<	while (status >= 0)
226	<	synchronized(this) { if (status >= 0) wait(); }
227	<	} catch (InterruptedException ie) {
228	<	onInterruptedWait();
229	<	}
230	<	}
231	<
227	<	/**
228	<	* Performs the actual monitor wait for awaitDone
229	<	*/
230	<	private void doAwaitDone(long startTime, long nanos) {
231	<	synchronized(this) {
232	<	try {
233	<	while (status >= 0) {
234	<	long nt = nanos - System.nanoTime() - startTime;
235	<	if (nt <= 0)
236	<	break;
237	<	wait(nt / 1000000, (int)(nt % 1000000));
225	>	if (((s = status) > 0 ||
226	>	(s == 0 &&
227	>	UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) &&
228	>	status > 0) {
229	>	synchronized (this) {
230	>	if (status > 0)
231	>	wait(millis);
232		}
239	–	} catch (InterruptedException ie) {
240	–	onInterruptedWait();
233		}
234	+	} catch (InterruptedException ie) {
235	+	// caller must check termination
236		}
237		}
238
245	–	// Awaiting completion
246	–
239		/**
240	<	* Sets status to indicate there is joiner, then waits for join,
241	<	* surrounded with pool notifications.
250	<	* @return status upon exit
240	>	* Blocks a non-worker-thread until completion.
241	>	* @return status upon completion
242		*/
243	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
253	<	ForkJoinPool pool = w == null? null : w.pool;
243	>	private int externalAwaitDone() {
244		int s;
245	<	while ((s = status) >= 0) {
246	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
247	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
248	<	doAwaitDone();
249	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
250	<	adjustPoolCountsOnUnblock(pool);
251	<	break;
245	>	if ((s = status) >= 0) {
246	>	boolean interrupted = false;
247	>	synchronized (this) {
248	>	while ((s = status) >= 0) {
249	>	if (s == 0)
250	>	UNSAFE.compareAndSwapInt(this, statusOffset,
251	>	0, SIGNAL);
252	>	else {
253	>	try {
254	>	wait();
255	>	} catch (InterruptedException ie) {
256	>	interrupted = true;
257	>	}
258	>	}
259	>	}
260		}
261	+	if (interrupted)
262	+	Thread.currentThread().interrupt();
263		}
264		return s;
265		}
266
267		/**
268	<	* Timed version of awaitDone
269	<	* @return status upon exit
268	>	* Blocks a non-worker-thread until completion or interruption or timeout.
269		*/
270	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
271	<	ForkJoinPool pool = w == null? null : w.pool;
270	>	private int externalInterruptibleAwaitDone(long millis)
271	>	throws InterruptedException {
272		int s;
273	<	while ((s = status) >= 0) {
274	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
275	<	long startTime = System.nanoTime();
276	<	if (pool == null || !pool.preJoin(this, false))
277	<	doAwaitDone(startTime, nanos);
278	<	if ((s = status) >= 0) {
279	<	adjustPoolCountsOnCancelledWait(pool);
280	<	s = status;
273	>	if (Thread.interrupted())
274	>	throw new InterruptedException();
275	>	if ((s = status) >= 0) {
276	>	synchronized (this) {
277	>	while ((s = status) >= 0) {
278	>	if (s == 0)
279	>	UNSAFE.compareAndSwapInt(this, statusOffset,
280	>	0, SIGNAL);
281	>	else {
282	>	wait(millis);
283	>	if (millis > 0L)
284	>	break;
285	>	}
286		}
283	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
284	–	adjustPoolCountsOnUnblock(pool);
285	–	break;
287		}
288		}
289		return s;
290		}
291
292		/**
293	<	* Notify pool that thread is unblocked. Called by signalled
294	<	* threads when woken by non-FJ threads (which is atypical).
293	>	* Primary execution method for stolen tasks. Unless done, calls
294	>	* exec and records status if completed, but doesn't wait for
295	>	* completion otherwise.
296		*/
297	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
298	<	int s;
299	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
300	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
301	<	pool.updateRunningCount(s);
297	>	final void doExec() {
298	>	if (status >= 0) {
299	>	boolean completed;
300	>	try {
301	>	completed = exec();
302	>	} catch (Throwable rex) {
303	>	setExceptionalCompletion(rex);
304	>	return;
305	>	}
306	>	if (completed)
307	>	setCompletion(NORMAL); // must be outside try block
308	>	}
309		}
310
311		/**
312	<	* Notify pool to adjust counts on cancelled or timed out wait
312	>	* Primary mechanics for join, get, quietlyJoin.
313	>	* @return status upon completion
314		*/
315	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
316	<	if (pool != null) {
317	<	int s;
318	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
319	<	if (casStatus(s, s - 1)) {
320	<	pool.updateRunningCount(1);
321	<	break;
315	>	private int doJoin() {
316	>	Thread t; ForkJoinWorkerThread w; int s; boolean completed;
317	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
318	>	if ((s = status) < 0)
319	>	return s;
320	>	if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) {
321	>	try {
322	>	completed = exec();
323	>	} catch (Throwable rex) {
324	>	return setExceptionalCompletion(rex);
325		}
326	+	if (completed)
327	+	return setCompletion(NORMAL);
328		}
329	+	return w.joinTask(this);
330		}
331	+	else
332	+	return externalAwaitDone();
333		}
334
335	<	private void onInterruptedWait() {
336	<	Thread t = Thread.currentThread();
337	<	if (t instanceof ForkJoinWorkerThread) {
338	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)t;
339	<	if (w.isTerminating())
340	<	cancelIgnoreExceptions();
341	<	}
342	<	else { // re-interrupt
343	<	try {
344	<	t.interrupt();
345	<	} catch (SecurityException ignore) {
346	<	}
335	>	/**
336	>	* Primary mechanics for invoke, quietlyInvoke.
337	>	* @return status upon completion
338	>	*/
339	>	private int doInvoke() {
340	>	int s; boolean completed;
341	>	if ((s = status) < 0)
342	>	return s;
343	>	try {
344	>	completed = exec();
345	>	} catch (Throwable rex) {
346	>	return setExceptionalCompletion(rex);
347		}
348	+	if (completed)
349	+	return setCompletion(NORMAL);
350	+	else
351	+	return doJoin();
352		}
353
354	<	// Recording and reporting exceptions
354	>	// Exception table support
355
356	<	private void setDoneExceptionally(Throwable rex) {
357	<	exceptionMap.put(this, rex);
358	<	setCompletion(EXCEPTIONAL);
359	<	}
356	>	/**
357	>	* Table of exceptions thrown by tasks, to enable reporting by
358	>	* callers. Because exceptions are rare, we don't directly keep
359	>	* them with task objects, but instead use a weak ref table.  Note
360	>	* that cancellation exceptions don't appear in the table, but are
361	>	* instead recorded as status values.
362	>	*
363	>	* Note: These statics are initialized below in static block.
364	>	*/
365	>	private static final ExceptionNode[] exceptionTable;
366	>	private static final ReentrantLock exceptionTableLock;
367	>	private static final ReferenceQueue<Object> exceptionTableRefQueue;
368
369		/**
370	<	* Throws the exception associated with status s;
341	<	* @throws the exception
370	>	* Fixed capacity for exceptionTable.
371		*/
372	<	private void reportException(int s) {
344	<	if ((s &= COMPLETION_MASK) < NORMAL) {
345	<	if (s == CANCELLED)
346	<	throw new CancellationException();
347	<	else
348	<	rethrowException(exceptionMap.get(this));
349	<	}
350	<	}
372	>	private static final int EXCEPTION_MAP_CAPACITY = 32;
373
374		/**
375	<	* Returns result or throws exception using j.u.c.Future conventions
376	<	* Only call when isDone known to be true.
375	>	* Key-value nodes for exception table.  The chained hash table
376	>	* uses identity comparisons, full locking, and weak references
377	>	* for keys. The table has a fixed capacity because it only
378	>	* maintains task exceptions long enough for joiners to access
379	>	* them, so should never become very large for sustained
380	>	* periods. However, since we do not know when the last joiner
381	>	* completes, we must use weak references and expunge them. We do
382	>	* so on each operation (hence full locking). Also, some thread in
383	>	* any ForkJoinPool will call helpExpungeStaleExceptions when its
384	>	* pool becomes isQuiescent.
385		*/
386	<	private V reportFutureResult()
387	<	throws ExecutionException, InterruptedException {
388	<	int s = status & COMPLETION_MASK;
389	<	if (s < NORMAL) {
390	<	Throwable ex;
391	<	if (s == CANCELLED)
392	<	throw new CancellationException();
393	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
394	<	throw new ExecutionException(ex);
365	<	if (Thread.interrupted())
366	<	throw new InterruptedException();
386	>	static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{
387	>	final Throwable ex;
388	>	ExceptionNode next;
389	>	final long thrower;  // use id not ref to avoid weak cycles
390	>	ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
391	>	super(task, exceptionTableRefQueue);
392	>	this.ex = ex;
393	>	this.next = next;
394	>	this.thrower = Thread.currentThread().getId();
395		}
368	–	return getRawResult();
396		}
397
398		/**
399	<	* Returns result or throws exception using j.u.c.Future conventions
400	<	* with timeouts
399	>	* Records exception and sets exceptional completion.
400	>	*
401	>	* @return status on exit
402		*/
403	<	private V reportTimedFutureResult()
404	<	throws InterruptedException, ExecutionException, TimeoutException {
405	<	Throwable ex;
406	<	int s = status & COMPLETION_MASK;
407	<	if (s == NORMAL)
408	<	return getRawResult();
409	<	if (s == CANCELLED)
410	<	throw new CancellationException();
411	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
412	<	throw new ExecutionException(ex);
413	<	if (Thread.interrupted())
414	<	throw new InterruptedException();
415	<	throw new TimeoutException();
403	>	private int setExceptionalCompletion(Throwable ex) {
404	>	int h = System.identityHashCode(this);
405	>	final ReentrantLock lock = exceptionTableLock;
406	>	lock.lock();
407	>	try {
408	>	expungeStaleExceptions();
409	>	ExceptionNode[] t = exceptionTable;
410	>	int i = h & (t.length - 1);
411	>	for (ExceptionNode e = t[i]; ; e = e.next) {
412	>	if (e == null) {
413	>	t[i] = new ExceptionNode(this, ex, t[i]);
414	>	break;
415	>	}
416	>	if (e.get() == this) // already present
417	>	break;
418	>	}
419	>	} finally {
420	>	lock.unlock();
421	>	}
422	>	return setCompletion(EXCEPTIONAL);
423		}
424
390	–	// internal execution methods
391	–
425		/**
426	<	* Calls exec, recording completion, and rethrowing exception if
394	<	* encountered. Caller should normally check status before calling
395	<	* @return true if completed normally
426	>	* Removes exception node and clears status
427		*/
428	<	private boolean tryExec() {
429	<	try { // try block must contain only call to exec
430	<	if (!exec())
431	<	return false;
432	<	} catch (Throwable rex) {
433	<	setDoneExceptionally(rex);
434	<	rethrowException(rex);
435	<	return false; // not reached
428	>	private void clearExceptionalCompletion() {
429	>	int h = System.identityHashCode(this);
430	>	final ReentrantLock lock = exceptionTableLock;
431	>	lock.lock();
432	>	try {
433	>	ExceptionNode[] t = exceptionTable;
434	>	int i = h & (t.length - 1);
435	>	ExceptionNode e = t[i];
436	>	ExceptionNode pred = null;
437	>	while (e != null) {
438	>	ExceptionNode next = e.next;
439	>	if (e.get() == this) {
440	>	if (pred == null)
441	>	t[i] = next;
442	>	else
443	>	pred.next = next;
444	>	break;
445	>	}
446	>	pred = e;
447	>	e = next;
448	>	}
449	>	expungeStaleExceptions();
450	>	status = 0;
451	>	} finally {
452	>	lock.unlock();
453		}
406	–	setNormalCompletion();
407	–	return true;
454		}
455
456		/**
457	<	* Main execution method used by worker threads. Invokes
458	<	* base computation unless already complete
457	>	* Returns a rethrowable exception for the given task, if
458	>	* available. To provide accurate stack traces, if the exception
459	>	* was not thrown by the current thread, we try to create a new
460	>	* exception of the same type as the one thrown, but with the
461	>	* recorded exception as its cause. If there is no such
462	>	* constructor, we instead try to use a no-arg constructor,
463	>	* followed by initCause, to the same effect. If none of these
464	>	* apply, or any fail due to other exceptions, we return the
465	>	* recorded exception, which is still correct, although it may
466	>	* contain a misleading stack trace.
467	>	*
468	>	* @return the exception, or null if none
469		*/
470	<	final void quietlyExec() {
471	<	if (status >= 0) {
470	>	private Throwable getThrowableException() {
471	>	if (status != EXCEPTIONAL)
472	>	return null;
473	>	int h = System.identityHashCode(this);
474	>	ExceptionNode e;
475	>	final ReentrantLock lock = exceptionTableLock;
476	>	lock.lock();
477	>	try {
478	>	expungeStaleExceptions();
479	>	ExceptionNode[] t = exceptionTable;
480	>	e = t[h & (t.length - 1)];
481	>	while (e != null && e.get() != this)
482	>	e = e.next;
483	>	} finally {
484	>	lock.unlock();
485	>	}
486	>	Throwable ex;
487	>	if (e == null || (ex = e.ex) == null)
488	>	return null;
489	>	if (e.thrower != Thread.currentThread().getId()) {
490	>	Class<? extends Throwable> ec = ex.getClass();
491		try {
492	<	if (!exec())
493	<	return;
494	<	} catch(Throwable rex) {
495	<	setDoneExceptionally(rex);
496	<	return;
492	>	Constructor<?> noArgCtor = null;
493	>	Constructor<?>[] cs = ec.getConstructors();// public ctors only
494	>	for (int i = 0; i < cs.length; ++i) {
495	>	Constructor<?> c = cs[i];
496	>	Class<?>[] ps = c.getParameterTypes();
497	>	if (ps.length == 0)
498	>	noArgCtor = c;
499	>	else if (ps.length == 1 && ps[0] == Throwable.class)
500	>	return (Throwable)(c.newInstance(ex));
501	>	}
502	>	if (noArgCtor != null) {
503	>	Throwable wx = (Throwable)(noArgCtor.newInstance());
504	>	wx.initCause(ex);
505	>	return wx;
506	>	}
507	>	} catch (Exception ignore) {
508		}
423	–	setNormalCompletion();
509		}
510	+	return ex;
511		}
512
513		/**
514	<	* Calls exec, recording but not rethrowing exception
429	<	* Caller should normally check status before calling
430	<	* @return true if completed normally
514	>	* Poll stale refs and remove them. Call only while holding lock.
515		*/
516	<	private boolean tryQuietlyInvoke() {
517	<	try {
518	<	if (!exec())
519	<	return false;
520	<	} catch (Throwable rex) {
521	<	setDoneExceptionally(rex);
522	<	return false;
516	>	private static void expungeStaleExceptions() {
517	>	for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
518	>	if (x instanceof ExceptionNode) {
519	>	ForkJoinTask<?> key = ((ExceptionNode)x).get();
520	>	ExceptionNode[] t = exceptionTable;
521	>	int i = System.identityHashCode(key) & (t.length - 1);
522	>	ExceptionNode e = t[i];
523	>	ExceptionNode pred = null;
524	>	while (e != null) {
525	>	ExceptionNode next = e.next;
526	>	if (e == x) {
527	>	if (pred == null)
528	>	t[i] = next;
529	>	else
530	>	pred.next = next;
531	>	break;
532	>	}
533	>	pred = e;
534	>	e = next;
535	>	}
536	>	}
537		}
440	–	setNormalCompletion();
441	–	return true;
538		}
539
540		/**
541	<	* Cancel, ignoring any exceptions it throws
541	>	* If lock is available, poll stale refs and remove them.
542	>	* Called from ForkJoinPool when pools become quiescent.
543		*/
544	<	final void cancelIgnoreExceptions() {
545	<	try {
546	<	cancel(false);
547	<	} catch(Throwable ignore) {
544	>	static final void helpExpungeStaleExceptions() {
545	>	final ReentrantLock lock = exceptionTableLock;
546	>	if (lock.tryLock()) {
547	>	try {
548	>	expungeStaleExceptions();
549	>	} finally {
550	>	lock.unlock();
551	>	}
552		}
553		}
554
555	+	/**
556	+	* Report the result of invoke or join; called only upon
557	+	* non-normal return of internal versions.
558	+	*/
559	+	private V reportResult() {
560	+	int s; Throwable ex;
561	+	if ((s = status) == CANCELLED)
562	+	throw new CancellationException();
563	+	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
564	+	UNSAFE.throwException(ex);
565	+	return getRawResult();
566	+	}
567	+
568		// public methods
569
570		/**
571		* Arranges to asynchronously execute this task.  While it is not
572		* necessarily enforced, it is a usage error to fork a task more
573	<	* than once unless it has completed and been reinitialized.  This
574	<	* method may be invoked only from within other ForkJoinTask
575	<	* computations. Attempts to invoke in other contexts result in
576	<	* exceptions or errors including ClassCastException.
573	>	* than once unless it has completed and been reinitialized.
574	>	* Subsequent modifications to the state of this task or any data
575	>	* it operates on are not necessarily consistently observable by
576	>	* any thread other than the one executing it unless preceded by a
577	>	* call to {@link #join} or related methods, or a call to {@link
578	>	* #isDone} returning {@code true}.
579	>	*
580	>	* <p>This method may be invoked only from within {@code
581	>	* ForkJoinPool} computations (as may be determined using method
582	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
583	>	* result in exceptions or errors, possibly including {@code
584	>	* ClassCastException}.
585	>	*
586	>	* @return {@code this}, to simplify usage
587		*/
588	<	public final void fork() {
589	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
588	>	public final ForkJoinTask<V> fork() {
589	>	((ForkJoinWorkerThread) Thread.currentThread())
590	>	.pushTask(this);
591	>	return this;
592		}
593
594		/**
595	<	* Returns the result of the computation when it is ready.
596	<	* This method differs from <tt>get</tt> in that abnormal
597	<	* completion results in RuntimeExceptions or Errors, not
598	<	* ExecutionExceptions.
595	>	* Returns the result of the computation when it {@link #isDone is
596	>	* done}.  This method differs from {@link #get()} in that
597	>	* abnormal completion results in {@code RuntimeException} or
598	>	* {@code Error}, not {@code ExecutionException}, and that
599	>	* interrupts of the calling thread do <em>not</em> cause the
600	>	* method to abruptly return by throwing {@code
601	>	* InterruptedException}.
602		*
603		* @return the computed result
604		*/
605		public final V join() {
606	<	ForkJoinWorkerThread w = getWorker();
607	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
608	<	reportException(awaitDone(w, true));
609	<	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();
606	>	if (doJoin() != NORMAL)
607	>	return reportResult();
608	>	else
609	>	return getRawResult();
610		}
611
612		/**
613	<	* Possibly executes other tasks until this task is ready, then
614	<	* returns the result of the computation.  This method may be more
615	<	* efficient than <tt>join</tt>, but is only applicable when there
616	<	* are no potemtial dependencies between continuation of the
617	<	* 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).
613	>	* Commences performing this task, awaits its completion if
614	>	* necessary, and returns its result, or throws an (unchecked)
615	>	* {@code RuntimeException} or {@code Error} if the underlying
616	>	* computation did so.
617	>	*
618		* @return the computed result
619		*/
620	<	public final V helpJoin() {
621	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
622	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
623	<	reportException(w.helpJoinTask(this));
624	<	return getRawResult();
620	>	public final V invoke() {
621	>	if (doInvoke() != NORMAL)
622	>	return reportResult();
623	>	else
624	>	return getRawResult();
625		}
626
627		/**
628	<	* Performs this task, awaits its completion if necessary, and
629	<	* return its result.
630	<	* @throws Throwable (a RuntimeException, Error, or unchecked
631	<	* exception) if the underlying computation did so.
632	<	* @return the computed result
628	>	* Forks the given tasks, returning when {@code isDone} holds for
629	>	* each task or an (unchecked) exception is encountered, in which
630	>	* case the exception is rethrown. If more than one task
631	>	* encounters an exception, then this method throws any one of
632	>	* these exceptions. If any task encounters an exception, the
633	>	* other may be cancelled. However, the execution status of
634	>	* individual tasks is not guaranteed upon exceptional return. The
635	>	* status of each task may be obtained using {@link
636	>	* #getException()} and related methods to check if they have been
637	>	* cancelled, completed normally or exceptionally, or left
638	>	* unprocessed.
639	>	*
640	>	* <p>This method may be invoked only from within {@code
641	>	* ForkJoinPool} computations (as may be determined using method
642	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
643	>	* result in exceptions or errors, possibly including {@code
644	>	* ClassCastException}.
645	>	*
646	>	* @param t1 the first task
647	>	* @param t2 the second task
648	>	* @throws NullPointerException if any task is null
649		*/
650	<	public final V invoke() {
651	<	if (status >= 0 && tryExec())
652	<	return getRawResult();
653	<	else
526	<	return join();
650	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
651	>	t2.fork();
652	>	t1.invoke();
653	>	t2.join();
654		}
655
656		/**
657	<	* Joins this task, without returning its result or throwing an
658	<	* exception. This method may be useful when processing
659	<	* collections of tasks when some have been cancelled or otherwise
660	<	* known to have aborted.
657	>	* Forks the given tasks, returning when {@code isDone} holds for
658	>	* each task or an (unchecked) exception is encountered, in which
659	>	* case the exception is rethrown. If more than one task
660	>	* encounters an exception, then this method throws any one of
661	>	* these exceptions. If any task encounters an exception, others
662	>	* may be cancelled. However, the execution status of individual
663	>	* tasks is not guaranteed upon exceptional return. The status of
664	>	* each task may be obtained using {@link #getException()} and
665	>	* related methods to check if they have been cancelled, completed
666	>	* normally or exceptionally, or left unprocessed.
667	>	*
668	>	* <p>This method may be invoked only from within {@code
669	>	* ForkJoinPool} computations (as may be determined using method
670	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
671	>	* result in exceptions or errors, possibly including {@code
672	>	* ClassCastException}.
673	>	*
674	>	* @param tasks the tasks
675	>	* @throws NullPointerException if any task is null
676		*/
677	<	public final void quietlyJoin() {
678	<	if (status >= 0) {
679	<	ForkJoinWorkerThread w = getWorker();
680	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
681	<	awaitDone(w, true);
677	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
678	>	Throwable ex = null;
679	>	int last = tasks.length - 1;
680	>	for (int i = last; i >= 0; --i) {
681	>	ForkJoinTask<?> t = tasks[i];
682	>	if (t == null) {
683	>	if (ex == null)
684	>	ex = new NullPointerException();
685	>	}
686	>	else if (i != 0)
687	>	t.fork();
688	>	else if (t.doInvoke() < NORMAL && ex == null)
689	>	ex = t.getException();
690		}
691	+	for (int i = 1; i <= last; ++i) {
692	+	ForkJoinTask<?> t = tasks[i];
693	+	if (t != null) {
694	+	if (ex != null)
695	+	t.cancel(false);
696	+	else if (t.doJoin() < NORMAL && ex == null)
697	+	ex = t.getException();
698	+	}
699	+	}
700	+	if (ex != null)
701	+	UNSAFE.throwException(ex);
702		}
703
704		/**
705	<	* Possibly executes other tasks until this task is ready.
705	>	* Forks all tasks in the specified collection, returning when
706	>	* {@code isDone} holds for each task or an (unchecked) exception
707	>	* is encountered, in which case the exception is rethrown. If
708	>	* more than one task encounters an exception, then this method
709	>	* throws any one of these exceptions. If any task encounters an
710	>	* exception, others may be cancelled. However, the execution
711	>	* status of individual tasks is not guaranteed upon exceptional
712	>	* return. The status of each task may be obtained using {@link
713	>	* #getException()} and related methods to check if they have been
714	>	* cancelled, completed normally or exceptionally, or left
715	>	* unprocessed.
716	>	*
717	>	* <p>This method may be invoked only from within {@code
718	>	* ForkJoinPool} computations (as may be determined using method
719	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
720	>	* result in exceptions or errors, possibly including {@code
721	>	* ClassCastException}.
722	>	*
723	>	* @param tasks the collection of tasks
724	>	* @return the tasks argument, to simplify usage
725	>	* @throws NullPointerException if tasks or any element are null
726		*/
727	<	public final void quietlyHelpJoin() {
728	<	if (status >= 0) {
729	<	ForkJoinWorkerThread w =
730	<	(ForkJoinWorkerThread)(Thread.currentThread());
550	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
551	<	w.helpJoinTask(this);
727	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
728	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
729	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
730	>	return tasks;
731		}
732	+	@SuppressWarnings("unchecked")
733	+	List<? extends ForkJoinTask<?>> ts =
734	+	(List<? extends ForkJoinTask<?>>) tasks;
735	+	Throwable ex = null;
736	+	int last = ts.size() - 1;
737	+	for (int i = last; i >= 0; --i) {
738	+	ForkJoinTask<?> t = ts.get(i);
739	+	if (t == null) {
740	+	if (ex == null)
741	+	ex = new NullPointerException();
742	+	}
743	+	else if (i != 0)
744	+	t.fork();
745	+	else if (t.doInvoke() < NORMAL && ex == null)
746	+	ex = t.getException();
747	+	}
748	+	for (int i = 1; i <= last; ++i) {
749	+	ForkJoinTask<?> t = ts.get(i);
750	+	if (t != null) {
751	+	if (ex != null)
752	+	t.cancel(false);
753	+	else if (t.doJoin() < NORMAL && ex == null)
754	+	ex = t.getException();
755	+	}
756	+	}
757	+	if (ex != null)
758	+	UNSAFE.throwException(ex);
759	+	return tasks;
760		}
761
762		/**
763	<	* Performs this task and awaits its completion if necessary,
764	<	* without returning its result or throwing an exception. This
765	<	* method may be useful when processing collections of tasks when
766	<	* some have been cancelled or otherwise known to have aborted.
763	>	* Attempts to cancel execution of this task. This attempt will
764	>	* fail if the task has already completed or could not be
765	>	* cancelled for some other reason. If successful, and this task
766	>	* has not started when {@code cancel} is called, execution of
767	>	* this task is suppressed. After this method returns
768	>	* successfully, unless there is an intervening call to {@link
769	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
770	>	* {@link #isDone}, and {@code cancel} will return {@code true}
771	>	* and calls to {@link #join} and related methods will result in
772	>	* {@code CancellationException}.
773	>	*
774	>	* <p>This method may be overridden in subclasses, but if so, must
775	>	* still ensure that these properties hold. In particular, the
776	>	* {@code cancel} method itself must not throw exceptions.
777	>	*
778	>	* <p>This method is designed to be invoked by <em>other</em>
779	>	* tasks. To terminate the current task, you can just return or
780	>	* throw an unchecked exception from its computation method, or
781	>	* invoke {@link #completeExceptionally}.
782	>	*
783	>	* @param mayInterruptIfRunning this value has no effect in the
784	>	* default implementation because interrupts are not used to
785	>	* control cancellation.
786	>	*
787	>	* @return {@code true} if this task is now cancelled
788		*/
789	<	public final void quietlyInvoke() {
790	<	if (status >= 0 && !tryQuietlyInvoke())
563	<	quietlyJoin();
789	>	public boolean cancel(boolean mayInterruptIfRunning) {
790	>	return setCompletion(CANCELLED) == CANCELLED;
791		}
792
793		/**
794	<	* Returns true if the computation performed by this task has
795	<	* completed (or has been cancelled).
796	<	* @return true if this computation has completed
794	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
795	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
796	>	* exceptions, but if it does anyway, we have no recourse during
797	>	* shutdown, so guard against this case.
798		*/
799	+	final void cancelIgnoringExceptions() {
800	+	try {
801	+	cancel(false);
802	+	} catch (Throwable ignore) {
803	+	}
804	+	}
805	+
806		public final boolean isDone() {
807		return status < 0;
808		}
809
575	–	/**
576	–	* Returns true if this task was cancelled.
577	–	* @return true if this task was cancelled
578	–	*/
810		public final boolean isCancelled() {
811	<	return (status & COMPLETION_MASK) == CANCELLED;
811	>	return status == CANCELLED;
812		}
813
814		/**
815	<	* Returns true if this task threw an exception or was cancelled
816	<	* @return true if this task threw an exception or was cancelled
815	>	* Returns {@code true} if this task threw an exception or was cancelled.
816	>	*
817	>	* @return {@code true} if this task threw an exception or was cancelled
818		*/
819	<	public final boolean completedAbnormally() {
820	<	return (status & COMPLETION_MASK) < NORMAL;
819	>	public final boolean isCompletedAbnormally() {
820	>	return status < NORMAL;
821		}
822
823		/**
824	<	* Returns the exception thrown by the base computation, or a
825	<	* CancellationException if cancelled, or null if none or if the
826	<	* method has not yet completed.
827	<	* @return the exception, or null if none
824	>	* Returns {@code true} if this task completed without throwing an
825	>	* exception and was not cancelled.
826	>	*
827	>	* @return {@code true} if this task completed without throwing an
828	>	* exception and was not cancelled
829		*/
830	<	public final Throwable getException() {
831	<	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);
830	>	public final boolean isCompletedNormally() {
831	>	return status == NORMAL;
832		}
833
834		/**
835	<	* Asserts that the results of this task's computation will not be
836	<	* used. If a cancellation occurs before this task is processed,
837	<	* 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.
835	>	* Returns the exception thrown by the base computation, or a
836	>	* {@code CancellationException} if cancelled, or {@code null} if
837	>	* none or if the method has not yet completed.
838		*
839	<	* @return true if this task is now cancelled
839	>	* @return the exception, or {@code null} if none
840		*/
841	<	public boolean cancel(boolean mayInterruptIfRunning) {
842	<	setCompletion(CANCELLED);
843	<	return (status & COMPLETION_MASK) == CANCELLED;
841	>	public final Throwable getException() {
842	>	int s = status;
843	>	return ((s >= NORMAL)    ? null :
844	>	(s == CANCELLED) ? new CancellationException() :
845	>	getThrowableException());
846		}
847
848		/**
849		* Completes this task abnormally, and if not already aborted or
850		* cancelled, causes it to throw the given exception upon
851	<	* <tt>join</tt> and related operations. This method may be used
851	>	* {@code join} and related operations. This method may be used
852		* to induce exceptions in asynchronous tasks, or to force
853	<	* completion of tasks that would not otherwise complete.  This
854	<	* method is overridable, but overridden versions must invoke
855	<	* <tt>super</tt> implementation to maintain guarantees.
856	<	* @param ex the exception to throw. If this exception is
857	<	* not a RuntimeException or Error, the actual exception thrown
858	<	* will be a RuntimeException with cause ex.
853	>	* completion of tasks that would not otherwise complete.  Its use
854	>	* in other situations is discouraged.  This method is
855	>	* overridable, but overridden versions must invoke {@code super}
856	>	* implementation to maintain guarantees.
857	>	*
858	>	* @param ex the exception to throw. If this exception is not a
859	>	* {@code RuntimeException} or {@code Error}, the actual exception
860	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
861		*/
862		public void completeExceptionally(Throwable ex) {
863	<	setDoneExceptionally((ex instanceof RuntimeException) ||
864	<	(ex instanceof Error)? ex :
865	<	new RuntimeException(ex));
863	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
864	>	(ex instanceof Error) ? ex :
865	>	new RuntimeException(ex));
866		}
867
868		/**
869		* Completes this task, and if not already aborted or cancelled,
870	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
871	<	* operations. This method may be used to provide results for
872	<	* asynchronous tasks, or to provide alternative handling for
873	<	* tasks that would not otherwise complete normally.
870	>	* returning the given value as the result of subsequent
871	>	* invocations of {@code join} and related operations. This method
872	>	* may be used to provide results for asynchronous tasks, or to
873	>	* provide alternative handling for tasks that would not otherwise
874	>	* complete normally. Its use in other situations is
875	>	* discouraged. This method is overridable, but overridden
876	>	* versions must invoke {@code super} implementation to maintain
877	>	* guarantees.
878		*
879	<	* @param value the result value for this task.
879	>	* @param value the result value for this task
880		*/
881		public void complete(V value) {
882		try {
883		setRawResult(value);
884	<	} catch(Throwable rex) {
885	<	setDoneExceptionally(rex);
884	>	} catch (Throwable rex) {
885	>	setExceptionalCompletion(rex);
886		return;
887		}
888	<	setNormalCompletion();
888	>	setCompletion(NORMAL);
889	>	}
890	>
891	>	/**
892	>	* Waits if necessary for the computation to complete, and then
893	>	* retrieves its result.
894	>	*
895	>	* @return the computed result
896	>	* @throws CancellationException if the computation was cancelled
897	>	* @throws ExecutionException if the computation threw an
898	>	* exception
899	>	* @throws InterruptedException if the current thread is not a
900	>	* member of a ForkJoinPool and was interrupted while waiting
901	>	*/
902	>	public final V get() throws InterruptedException, ExecutionException {
903	>	int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ?
904	>	doJoin() : externalInterruptibleAwaitDone(0L);
905	>	Throwable ex;
906	>	if (s == CANCELLED)
907	>	throw new CancellationException();
908	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
909	>	throw new ExecutionException(ex);
910	>	return getRawResult();
911	>	}
912	>
913	>	/**
914	>	* Waits if necessary for at most the given time for the computation
915	>	* to complete, and then retrieves its result, if available.
916	>	*
917	>	* @param timeout the maximum time to wait
918	>	* @param unit the time unit of the timeout argument
919	>	* @return the computed result
920	>	* @throws CancellationException if the computation was cancelled
921	>	* @throws ExecutionException if the computation threw an
922	>	* exception
923	>	* @throws InterruptedException if the current thread is not a
924	>	* member of a ForkJoinPool and was interrupted while waiting
925	>	* @throws TimeoutException if the wait timed out
926	>	*/
927	>	public final V get(long timeout, TimeUnit unit)
928	>	throws InterruptedException, ExecutionException, TimeoutException {
929	>	Thread t = Thread.currentThread();
930	>	if (t instanceof ForkJoinWorkerThread) {
931	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
932	>	long nanos = unit.toNanos(timeout);
933	>	if (status >= 0) {
934	>	boolean completed = false;
935	>	if (w.unpushTask(this)) {
936	>	try {
937	>	completed = exec();
938	>	} catch (Throwable rex) {
939	>	setExceptionalCompletion(rex);
940	>	}
941	>	}
942	>	if (completed)
943	>	setCompletion(NORMAL);
944	>	else if (status >= 0 && nanos > 0)
945	>	w.pool.timedAwaitJoin(this, nanos);
946	>	}
947	>	}
948	>	else {
949	>	long millis = unit.toMillis(timeout);
950	>	if (millis > 0)
951	>	externalInterruptibleAwaitDone(millis);
952	>	}
953	>	int s = status;
954	>	if (s != NORMAL) {
955	>	Throwable ex;
956	>	if (s == CANCELLED)
957	>	throw new CancellationException();
958	>	if (s != EXCEPTIONAL)
959	>	throw new TimeoutException();
960	>	if ((ex = getThrowableException()) != null)
961	>	throw new ExecutionException(ex);
962	>	}
963	>	return getRawResult();
964	>	}
965	>
966	>	/**
967	>	* Joins this task, without returning its result or throwing its
968	>	* exception. This method may be useful when processing
969	>	* collections of tasks when some have been cancelled or otherwise
970	>	* known to have aborted.
971	>	*/
972	>	public final void quietlyJoin() {
973	>	doJoin();
974	>	}
975	>
976	>	/**
977	>	* Commences performing this task and awaits its completion if
978	>	* necessary, without returning its result or throwing its
979	>	* exception.
980	>	*/
981	>	public final void quietlyInvoke() {
982	>	doInvoke();
983	>	}
984	>
985	>	/**
986	>	* Possibly executes tasks until the pool hosting the current task
987	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
988	>	* be of use in designs in which many tasks are forked, but none
989	>	* are explicitly joined, instead executing them until all are
990	>	* processed.
991	>	*
992	>	* <p>This method may be invoked only from within {@code
993	>	* ForkJoinPool} computations (as may be determined using method
994	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
995	>	* result in exceptions or errors, possibly including {@code
996	>	* ClassCastException}.
997	>	*/
998	>	public static void helpQuiesce() {
999	>	((ForkJoinWorkerThread) Thread.currentThread())
1000	>	.helpQuiescePool();
1001		}
1002
1003		/**
1004		* Resets the internal bookkeeping state of this task, allowing a
1005	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
1005	>	* subsequent {@code fork}. This method allows repeated reuse of
1006		* this task, but only if reuse occurs when this task has either
1007		* never been forked, or has been forked, then completed and all
1008		* outstanding joins of this task have also completed. Effects
1009	<	* under any other usage conditions are not guaranteed, and are
1010	<	* almost surely wrong. This method may be useful when executing
1009	>	* under any other usage conditions are not guaranteed.
1010	>	* This method may be useful when executing
1011		* pre-constructed trees of subtasks in loops.
1012	+	*
1013	+	* <p>Upon completion of this method, {@code isDone()} reports
1014	+	* {@code false}, and {@code getException()} reports {@code
1015	+	* null}. However, the value returned by {@code getRawResult} is
1016	+	* unaffected. To clear this value, you can invoke {@code
1017	+	* setRawResult(null)}.
1018		*/
1019		public void reinitialize() {
1020	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
1021	<	exceptionMap.remove(this);
1022	<	status = 0;
1020	>	if (status == EXCEPTIONAL)
1021	>	clearExceptionalCompletion();
1022	>	else
1023	>	status = 0;
1024		}
1025
1026		/**
1027	<	* Tries to unschedule this task for execution. This method will
1028	<	* typically succeed if this task is the next task that would be
1029	<	* executed by the current thread, and will typically fail (return
1030	<	* false) otherwise. This method may be useful when arranging
1031	<	* faster local processing of tasks that could have been, but were
697	<	* not, stolen.
698	<	* @return true if unforked
1027	>	* Returns the pool hosting the current task execution, or null
1028	>	* if this task is executing outside of any ForkJoinPool.
1029	>	*
1030	>	* @see #inForkJoinPool
1031	>	* @return the pool, or {@code null} if none
1032		*/
1033	<	public boolean tryUnfork() {
1034	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
1033	>	public static ForkJoinPool getPool() {
1034	>	Thread t = Thread.currentThread();
1035	>	return (t instanceof ForkJoinWorkerThread) ?
1036	>	((ForkJoinWorkerThread) t).pool : null;
1037		}
1038
1039		/**
1040	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
1041	<	* of them or an exception is encountered. This method may be
1042	<	* invoked only from within other ForkJoinTask
1043	<	* computations. Attempts to invoke in other contexts result in
1044	<	* exceptions or errors including ClassCastException.
1045	<	* @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.
1040	>	* Returns {@code true} if the current thread is a {@link
1041	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
1042	>	*
1043	>	* @return {@code true} if the current thread is a {@link
1044	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
1045	>	* or {@code false} otherwise
1046		*/
1047	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
1048	<	t2.fork();
717	<	t1.invoke();
718	<	t2.join();
1047	>	public static boolean inForkJoinPool() {
1048	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
1049		}
1050
1051		/**
1052	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
1053	<	* all of them. If any task encounters an exception, others may be
1054	<	* cancelled.  This method may be invoked only from within other
1055	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1056	<	* result in exceptions or errors including ClassCastException.
1057	<	* @param tasks the array of tasks
1058	<	* @throws NullPointerException if tasks or any element are null.
1059	<	* @throws RuntimeException or Error if any task did so.
1060	<	*/
1061	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
1062	<	Throwable ex = null;
1063	<	int last = tasks.length - 1;
1064	<	for (int i = last; i >= 0; --i) {
1065	<	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);
762	<	}
763	<
764	<	/**
765	<	* Forks all tasks in the collection, returning when
766	<	* <tt>isDone</tt> holds for all of them. If any task encounters
767	<	* 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	>	* Tries to unschedule this task for execution. This method will
1053	>	* typically succeed if this task is the most recently forked task
1054	>	* by the current thread, and has not commenced executing in
1055	>	* another thread.  This method may be useful when arranging
1056	>	* alternative local processing of tasks that could have been, but
1057	>	* were not, stolen.
1058	>	*
1059	>	* <p>This method may be invoked only from within {@code
1060	>	* ForkJoinPool} 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 {@code true} if unforked
1066		*/
1067	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
1068	<	if (!(tasks instanceof List)) {
1069	<	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);
1067	>	public boolean tryUnfork() {
1068	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1069	>	.unpushTask(this);
1070		}
1071
1072		/**
1073	<	* Possibly executes tasks until the pool hosting the current task
1074	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
1075	<	* designs in which many tasks are forked, but none are explicitly
1076	<	* joined, instead executing them until all are processed.
1073	>	* Returns an estimate of the number of tasks that have been
1074	>	* forked by the current worker thread but not yet executed. This
1075	>	* value may be useful for heuristic decisions about whether to
1076	>	* fork other tasks.
1077	>	*
1078	>	* <p>This method may be invoked only from within {@code
1079	>	* ForkJoinPool} 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 number of tasks
1085		*/
1086	<	public static void helpQuiesce() {
1087	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1088	<	helpQuiescePool();
1086	>	public static int getQueuedTaskCount() {
1087	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1088	>	.getQueueSize();
1089		}
1090
1091		/**
1092	<	* Returns a estimate of how many more locally queued tasks are
1092	>	* Returns an estimate of how many more locally queued tasks are
1093		* held by the current worker thread than there are other worker
1094	<	* threads that might want to steal them.  This value may be
1095	<	* useful for heuristic decisions about whether to fork other
1096	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
1097	<	* worker should aim to maintain a small constant surplus (for
1098	<	* example, 3) of tasks, and to process computations locally if
1099	<	* this threshold is exceeded.
1094	>	* threads that might steal them.  This value may be useful for
1095	>	* heuristic decisions about whether to fork other tasks. In many
1096	>	* usages of ForkJoinTasks, at steady state, each worker should
1097	>	* aim to maintain a small constant surplus (for example, 3) of
1098	>	* tasks, and to process computations locally if this threshold is
1099	>	* exceeded.
1100	>	*
1101	>	* <p>This method may be invoked only from within {@code
1102	>	* ForkJoinPool} 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 the surplus number of tasks, which may be negative
1108		*/
1109	<	public static int surplus() {
1110	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
1109	>	public static int getSurplusQueuedTaskCount() {
1110	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1111		.getEstimatedSurplusTaskCount();
1112		}
1113
1114	<	// Extension kit
1114	>	// Extension methods
1115
1116		/**
1117	<	* Returns the result that would be returned by <tt>join</tt>, or
1118	<	* null if this task is not known to have been completed.  This
1119	<	* method is designed to aid debugging, as well as to support
1120	<	* extensions. Its use in any other context is discouraged.
1117	>	* Returns the result that would be returned by {@link #join}, even
1118	>	* if this task completed abnormally, or {@code null} if this task
1119	>	* is not known to have been completed.  This method is designed
1120	>	* to aid debugging, as well as to support extensions. Its use in
1121	>	* any other context is discouraged.
1122		*
1123	<	* @return the result, or null if not completed.
1123	>	* @return the result, or {@code null} if not completed
1124		*/
1125		public abstract V getRawResult();
1126
#	Line 865 | Line 1139 | public abstract class ForkJoinTask<V> im
1139		* called otherwise. The return value controls whether this task
1140		* is considered to be done normally. It may return false in
1141		* asynchronous actions that require explicit invocations of
1142	<	* <tt>complete</tt> to become joinable. It may throw exceptions
1143	<	* to indicate abnormal exit.
1144	<	* @return true if completed normally
1145	<	* @throws Error or RuntimeException if encountered during computation
1142	>	* {@link #complete} to become joinable. It may also throw an
1143	>	* (unchecked) exception to indicate abnormal exit.
1144	>	*
1145	>	* @return {@code true} if completed normally
1146		*/
1147		protected abstract boolean exec();
1148
1149	+	/**
1150	+	* Returns, but does not unschedule or execute, a task queued by
1151	+	* the current thread but not yet executed, if one is immediately
1152	+	* available. There is no guarantee that this task will actually
1153	+	* be polled or executed next. Conversely, this method may return
1154	+	* null even if a task exists but cannot be accessed without
1155	+	* contention with other threads.  This method is designed
1156	+	* primarily to support extensions, and is unlikely to be useful
1157	+	* otherwise.
1158	+	*
1159	+	* <p>This method may be invoked only from within {@code
1160	+	* ForkJoinPool} computations (as may be determined using method
1161	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1162	+	* result in exceptions or errors, possibly including {@code
1163	+	* ClassCastException}.
1164	+	*
1165	+	* @return the next task, or {@code null} if none are available
1166	+	*/
1167	+	protected static ForkJoinTask<?> peekNextLocalTask() {
1168	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1169	+	.peekTask();
1170	+	}
1171	+
1172	+	/**
1173	+	* Unschedules and returns, without executing, the next task
1174	+	* queued by the current thread but not yet executed.  This method
1175	+	* is designed primarily to support extensions, and is unlikely to
1176	+	* be useful otherwise.
1177	+	*
1178	+	* <p>This method may be invoked only from within {@code
1179	+	* ForkJoinPool} computations (as may be determined using method
1180	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1181	+	* result in exceptions or errors, possibly including {@code
1182	+	* ClassCastException}.
1183	+	*
1184	+	* @return the next task, or {@code null} if none are available
1185	+	*/
1186	+	protected static ForkJoinTask<?> pollNextLocalTask() {
1187	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1188	+	.pollLocalTask();
1189	+	}
1190	+
1191	+	/**
1192	+	* Unschedules and returns, without executing, the next task
1193	+	* queued by the current thread but not yet executed, if one is
1194	+	* available, or if not available, a task that was forked by some
1195	+	* other thread, if available. Availability may be transient, so a
1196	+	* {@code null} result does not necessarily imply quiescence
1197	+	* of the pool this task is operating in.  This method is designed
1198	+	* primarily to support extensions, and is unlikely to be useful
1199	+	* otherwise.
1200	+	*
1201	+	* <p>This method may be invoked only from within {@code
1202	+	* ForkJoinPool} computations (as may be determined using method
1203	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1204	+	* result in exceptions or errors, possibly including {@code
1205	+	* ClassCastException}.
1206	+	*
1207	+	* @return a task, or {@code null} if none are available
1208	+	*/
1209	+	protected static ForkJoinTask<?> pollTask() {
1210	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1211	+	.pollTask();
1212	+	}
1213	+
1214	+	/**
1215	+	* Adaptor for Runnables. This implements RunnableFuture
1216	+	* to be compliant with AbstractExecutorService constraints
1217	+	* when used in ForkJoinPool.
1218	+	*/
1219	+	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1220	+	implements RunnableFuture<T> {
1221	+	final Runnable runnable;
1222	+	final T resultOnCompletion;
1223	+	T result;
1224	+	AdaptedRunnable(Runnable runnable, T result) {
1225	+	if (runnable == null) throw new NullPointerException();
1226	+	this.runnable = runnable;
1227	+	this.resultOnCompletion = result;
1228	+	}
1229	+	public T getRawResult() { return result; }
1230	+	public void setRawResult(T v) { result = v; }
1231	+	public boolean exec() {
1232	+	runnable.run();
1233	+	result = resultOnCompletion;
1234	+	return true;
1235	+	}
1236	+	public void run() { invoke(); }
1237	+	private static final long serialVersionUID = 5232453952276885070L;
1238	+	}
1239	+
1240	+	/**
1241	+	* Adaptor for Callables
1242	+	*/
1243	+	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1244	+	implements RunnableFuture<T> {
1245	+	final Callable<? extends T> callable;
1246	+	T result;
1247	+	AdaptedCallable(Callable<? extends T> callable) {
1248	+	if (callable == null) throw new NullPointerException();
1249	+	this.callable = callable;
1250	+	}
1251	+	public T getRawResult() { return result; }
1252	+	public void setRawResult(T v) { result = v; }
1253	+	public boolean exec() {
1254	+	try {
1255	+	result = callable.call();
1256	+	return true;
1257	+	} catch (Error err) {
1258	+	throw err;
1259	+	} catch (RuntimeException rex) {
1260	+	throw rex;
1261	+	} catch (Exception ex) {
1262	+	throw new RuntimeException(ex);
1263	+	}
1264	+	}
1265	+	public void run() { invoke(); }
1266	+	private static final long serialVersionUID = 2838392045355241008L;
1267	+	}
1268	+
1269	+	/**
1270	+	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1271	+	* method of the given {@code Runnable} as its action, and returns
1272	+	* a null result upon {@link #join}.
1273	+	*
1274	+	* @param runnable the runnable action
1275	+	* @return the task
1276	+	*/
1277	+	public static ForkJoinTask<?> adapt(Runnable runnable) {
1278	+	return new AdaptedRunnable<Void>(runnable, null);
1279	+	}
1280	+
1281	+	/**
1282	+	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1283	+	* method of the given {@code Runnable} as its action, and returns
1284	+	* the given result upon {@link #join}.
1285	+	*
1286	+	* @param runnable the runnable action
1287	+	* @param result the result upon completion
1288	+	* @return the task
1289	+	*/
1290	+	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1291	+	return new AdaptedRunnable<T>(runnable, result);
1292	+	}
1293	+
1294	+	/**
1295	+	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1296	+	* method of the given {@code Callable} as its action, and returns
1297	+	* its result upon {@link #join}, translating any checked exceptions
1298	+	* encountered into {@code RuntimeException}.
1299	+	*
1300	+	* @param callable the callable action
1301	+	* @return the task
1302	+	*/
1303	+	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1304	+	return new AdaptedCallable<T>(callable);
1305	+	}
1306	+
1307		// Serialization support
1308
1309		private static final long serialVersionUID = -7721805057305804111L;
1310
1311		/**
1312	<	* Save the state to a stream.
1312	>	* Saves the state to a stream (that is, serializes it).
1313		*
1314		* @serialData the current run status and the exception thrown
1315	<	* during execution, or null if none.
1315	>	* during execution, or {@code null} if none
1316		* @param s the stream
1317		*/
1318		private void writeObject(java.io.ObjectOutputStream s)
#	Line 890 | Line 1322 | public abstract class ForkJoinTask<V> im
1322		}
1323
1324		/**
1325	<	* Reconstitute the instance from a stream.
1325	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1326	>	*
1327		* @param s the stream
1328		*/
1329		private void readObject(java.io.ObjectInputStream s)
1330		throws java.io.IOException, ClassNotFoundException {
1331		s.defaultReadObject();
899	–	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1332		Object ex = s.readObject();
1333		if (ex != null)
1334	<	setDoneExceptionally((Throwable)ex);
1334	>	setExceptionalCompletion((Throwable)ex);
1335		}
1336
1337	<	// Temporary Unsafe mechanics for preliminary release
1338	<
1339	<	static final Unsafe _unsafe;
908	<	static final long statusOffset;
909	<
1337	>	// Unsafe mechanics
1338	>	private static final sun.misc.Unsafe UNSAFE;
1339	>	private static final long statusOffset;
1340		static {
1341	+	exceptionTableLock = new ReentrantLock();
1342	+	exceptionTableRefQueue = new ReferenceQueue<Object>();
1343	+	exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY];
1344		try {
1345	<	if (ForkJoinTask.class.getClassLoader() != null) {
1346	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
914	<	f.setAccessible(true);
915	<	_unsafe = (Unsafe)f.get(null);
916	<	}
917	<	else
918	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
1345	>	UNSAFE = getUnsafe();
1346	>	statusOffset = UNSAFE.objectFieldOffset
1347		(ForkJoinTask.class.getDeclaredField("status"));
1348	<	} catch (Exception ex) { throw new Error(ex); }
1348	>	} catch (Exception e) {
1349	>	throw new Error(e);
1350	>	}
1351		}
1352
1353	+	/**
1354	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1355	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1356	+	* into a jdk.
1357	+	*
1358	+	* @return a sun.misc.Unsafe
1359	+	*/
1360	+	private static sun.misc.Unsafe getUnsafe() {
1361	+	try {
1362	+	return sun.misc.Unsafe.getUnsafe();
1363	+	} catch (SecurityException se) {
1364	+	try {
1365	+	return java.security.AccessController.doPrivileged
1366	+	(new java.security
1367	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1368	+	public sun.misc.Unsafe run() throws Exception {
1369	+	java.lang.reflect.Field f = sun.misc
1370	+	.Unsafe.class.getDeclaredField("theUnsafe");
1371	+	f.setAccessible(true);
1372	+	return (sun.misc.Unsafe) f.get(null);
1373	+	}});
1374	+	} catch (java.security.PrivilegedActionException e) {
1375	+	throw new RuntimeException("Could not initialize intrinsics",
1376	+	e.getCause());
1377	+	}
1378	+	}
1379	+	}
1380		}

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