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Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.7 by jsr166, Mon Jul 20 21:45:06 2009 UTC vs.
Revision 1.80 by jsr166, Fri Jul 1 18:30:14 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 {@link
28	<	* ForkJoinPool}.  A ForkJoinTask is a thread-like entity that is much
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" ForkJoinTask begins execution when submitted to a
34	<	* {@link ForkJoinPool}. Once started, it will usually in turn start
35	<	* other subtasks.  As indicated by the name of this class, many
36	<	* programs using ForkJoinTasks employ only methods <code>fork</code>
37	<	* and <code>join</code>, or derivatives such as
38	<	* <code>invokeAll</code>.  However, this class also provides a number
39	<	* of other methods that can come into play in advanced usages, as
40	<	* well as extension mechanics that allow support of new forms of
41	<	* fork/join processing.
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 ForkJoinTask is a lightweight form of {@link Future}.  The
44	<	* efficiency of ForkJoinTasks stems from a set of restrictions (that
45	<	* are only partially statically enforceable) reflecting their
46	<	* intended use as computational tasks calculating pure functions or
47	<	* operating on purely isolated objects.  The primary coordination
48	<	* mechanisms are {@link #fork}, that arranges asynchronous execution,
49	<	* and {@link #join}, that doesn't proceed until the task's result has
50	<	* been computed.  Computations should avoid <code>synchronized</code>
51	<	* methods or blocks, and should minimize other blocking
52	<	* synchronization apart from joining other tasks or using
53	<	* synchronizers such as Phasers that are advertised to cooperate with
54	<	* fork/join scheduling. Tasks should also not perform blocking IO,
55	<	* and should ideally access variables that are completely independent
56	<	* of those accessed by other running tasks. Minor breaches of these
57	<	* restrictions, for example using shared output streams, may be
58	<	* tolerable in practice, but frequent use may result in poor
59	<	* performance, and the potential to indefinitely stall if the number
60	<	* of threads not waiting for IO or other external synchronization
61	<	* becomes exhausted. This usage restriction is in part enforced by
62	<	* not permitting checked exceptions such as <code>IOExceptions</code>
63	<	* to be thrown. However, computations may still encounter unchecked
64	<	* exceptions, that are rethrown to callers attempting join
65	<	* them. These exceptions may additionally include
66	<	* RejectedExecutionExceptions stemming from internal resource
67	<	* exhaustion such as failure to allocate internal task queues.
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</code>
78	<	* conventions. Method {@link #helpJoin} enables callers to actively
79	<	* execute other tasks while awaiting joins, which is sometimes more
80	<	* efficient but only applies when all subtasks are known to be
81	<	* strictly tree-structured. Method {@link #invoke} is semantically
66	<	* equivalent to <code>fork(); join()</code> but always attempts to
67	<	* begin execution in the current thread. The "<em>quiet</em>" forms
68	<	* of these methods do not extract results or report exceptions. These
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</code> (available in multiple versions)
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 ForkJoinTask class is not usually directly subclassed.
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.  Normally, a concrete
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</code>
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</code> access (to allow
109	<	* instances of different task subclasses to call each others
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. Attempts to invoke them in other contexts result in
112	<	* exceptions or errors possibly including ClassCastException.
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</code> because their
127	<	* implementations are intrinsically tied to the underlying
128	<	* lightweight task scheduling framework, and so cannot be overridden.
129	<	* Developers creating new basic styles of fork/join processing should
130	<	* minimally implement <code>protected</code> methods
131	<	* <code>exec</code>, <code>setRawResult</code>, and
132	<	* <code>getRawResult</code>, while also introducing an abstract
133	<	* computational method that can be implemented in its subclasses,
134	<	* possibly relying on other <code>protected</code> methods provided
96	<	* by this class.
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.
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	<	* <p>ForkJoinTasks are <code>Serializable</code>, which enables them
156	<	* to be used in extensions such as remote execution frameworks. It is
107	<	* in general sensible to serialize tasks only before or after, but
108	<	* not during execution. Serialization is not relied on during
109	<	* execution itself.
155	>	* @since 1.7
156	>	* @author Doug Lea
157		*/
158		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
159
160	<	/**
161	<	* Run control status bits packed into a single int to minimize
162	<	* footprint and to ensure atomicity (via CAS).  Status is
163	<	* initially zero, and takes on nonnegative values until
164	<	* completed, upon which status holds COMPLETED. CANCELLED, or
165	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
166	<	* blocking waits by other threads have SIGNAL_MASK bits set --
167	<	* bit 15 for external (nonFJ) waits, and the rest a count of
168	<	* waiting FJ threads.  (This representation relies on
169	<	* ForkJoinPool max thread limits). Completion of a stolen task
170	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
171	<	* though suboptimal for some purposes, we use basic builtin
172	<	* wait/notify to take advantage of "monitor inflation" in JVMs
173	<	* that we would otherwise need to emulate to avoid adding further
174	<	* per-task bookkeeping overhead. Note that bits 16-28 are
175	<	* currently unused. Also value 0x80000000 is available as spare
176	<	* completion value.
177	<	*/
178	<	volatile int status; // accessed directy by pool and workers
179	<
180	<	static final int COMPLETION_MASK      = 0xe0000000;
181	<	static final int NORMAL               = 0xe0000000; // == mask
182	<	static final int CANCELLED            = 0xc0000000;
183	<	static final int EXCEPTIONAL          = 0xa0000000;
184	<	static final int SIGNAL_MASK          = 0x0000ffff;
185	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
186	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
187	<
188	<	/**
189	<	* Table of exceptions thrown by tasks, to enable reporting by
190	<	* callers. Because exceptions are rare, we don't directly keep
191	<	* them with task objects, but instead us a weak ref table.  Note
192	<	* that cancellation exceptions don't appear in the table, but are
193	<	* instead recorded as status values.
194	<	* Todo: Use ConcurrentReferenceHashMap
195	<	*/
196	<	static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
150	<	Collections.synchronizedMap
151	<	(new WeakHashMap<ForkJoinTask<?>, Throwable>());
152	<
153	<	// within-package utilities
154	<
155	<	/**
156	<	* Get current worker thread, or null if not a worker thread
157	<	*/
158	<	static ForkJoinWorkerThread getWorker() {
159	<	Thread t = Thread.currentThread();
160	<	return ((t instanceof ForkJoinWorkerThread)?
161	<	(ForkJoinWorkerThread)t : null);
162	<	}
163	<
164	<	final boolean casStatus(int cmp, int val) {
165	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
166	<	}
167	<
168	<	/**
169	<	* Workaround for not being able to rethrow unchecked exceptions.
170	<	*/
171	<	static void rethrowException(Throwable ex) {
172	<	if (ex != null)
173	<	_unsafe.throwException(ex);
174	<	}
175	<
176	<	// 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.
165	>	*
166	>	* The methods of this class are more-or-less layered into
167	>	* (1) basic status maintenance
168	>	* (2) execution and awaiting completion
169	>	* (3) user-level methods that additionally report results.
170	>	* This is sometimes hard to see because this file orders exported
171	>	* methods in a way that flows well in javadocs.
172	>	*/
173	>
174	>	/*
175	>	* The status field holds run control status bits packed into a
176	>	* single int to minimize footprint and to ensure atomicity (via
177	>	* CAS).  Status is initially zero, and takes on nonnegative
178	>	* values until completed, upon which status holds value
179	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
180	>	* waits by other threads have the SIGNAL bit set.  Completion of
181	>	* a stolen task with SIGNAL set awakens any waiters via
182	>	* notifyAll. Even though suboptimal for some purposes, we use
183	>	* basic builtin wait/notify to take advantage of "monitor
184	>	* inflation" in JVMs that we would otherwise need to emulate to
185	>	* avoid adding further per-task bookkeeping overhead.  We want
186	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
187	>	* techniques, so use some odd coding idioms that tend to avoid
188	>	* them.
189	>	*/
190	>
191	>	/** The run status of this task */
192	>	volatile int status; // accessed directly by pool and workers
193	>	private static final int NORMAL      = -1;
194	>	private static final int CANCELLED   = -2;
195	>	private static final int EXCEPTIONAL = -3;
196	>	private static final int SIGNAL      =  1;
197
198		/**
199	<	* Mark completion and wake up threads waiting to join this task.
199	>	* Marks completion and wakes up threads waiting to join this task,
200	>	* also clearing signal request bits.
201	>	*
202		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
203	+	* @return completion status on exit
204		*/
205	<	final void setCompletion(int completion) {
206	<	ForkJoinPool pool = getPool();
207	<	if (pool != null) {
208	<	int s; // Clear signal bits while setting completion status
209	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
210	<
211	<	if ((s & SIGNAL_MASK) != 0) {
212	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
190	<	pool.updateRunningCount(s);
191	<	synchronized(this) { notifyAll(); }
205	>	private int setCompletion(int completion) {
206	>	for (int s;;) {
207	>	if ((s = status) < 0)
208	>	return s;
209	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
210	>	if (s != 0)
211	>	synchronized (this) { notifyAll(); }
212	>	return completion;
213		}
214		}
194	–	else
195	–	externallySetCompletion(completion);
215		}
216
217		/**
218	<	* Version of setCompletion for non-FJ threads.  Leaves signal
219	<	* bits for unblocked threads to adjust, and always notifies.
218	>	* Tries to block a worker thread until completed or timed out.
219	>	* Uses Object.wait time argument conventions.
220	>	* May fail on contention or interrupt.
221	>	*
222	>	* @param millis if > 0, wait time.
223		*/
224	<	private void externallySetCompletion(int completion) {
224	>	final void tryAwaitDone(long millis) {
225		int s;
204	–	do;while ((s = status) >= 0 &&
205	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
206	–	synchronized(this) { notifyAll(); }
207	–	}
208	–
209	–	/**
210	–	* Sets status to indicate normal completion
211	–	*/
212	–	final void setNormalCompletion() {
213	–	// Try typical fast case -- single CAS, no signal, not already done.
214	–	// Manually expand casStatus to improve chances of inlining it
215	–	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
216	–	setCompletion(NORMAL);
217	–	}
218	–
219	–	// internal waiting and notification
220	–
221	–	/**
222	–	* Performs the actual monitor wait for awaitDone
223	–	*/
224	–	private void doAwaitDone() {
225	–	// Minimize lock bias and in/de-flation effects by maximizing
226	–	// chances of waiting inside sync
226		try {
227	<	while (status >= 0)
228	<	synchronized(this) { if (status >= 0) wait(); }
229	<	} catch (InterruptedException ie) {
230	<	onInterruptedWait();
231	<	}
232	<	}
233	<
235	<	/**
236	<	* Performs the actual monitor wait for awaitDone
237	<	*/
238	<	private void doAwaitDone(long startTime, long nanos) {
239	<	synchronized(this) {
240	<	try {
241	<	while (status >= 0) {
242	<	long nt = nanos - System.nanoTime() - startTime;
243	<	if (nt <= 0)
244	<	break;
245	<	wait(nt / 1000000, (int)(nt % 1000000));
227	>	if (((s = status) > 0 ||
228	>	(s == 0 &&
229	>	UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) &&
230	>	status > 0) {
231	>	synchronized (this) {
232	>	if (status > 0)
233	>	wait(millis);
234		}
247	–	} catch (InterruptedException ie) {
248	–	onInterruptedWait();
235		}
236	+	} catch (InterruptedException ie) {
237	+	// caller must check termination
238		}
239		}
240
253	–	// Awaiting completion
254	–
241		/**
242	<	* Sets status to indicate there is joiner, then waits for join,
243	<	* surrounded with pool notifications.
258	<	* @return status upon exit
242	>	* Blocks a non-worker-thread until completion.
243	>	* @return status upon completion
244		*/
245	<	private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
261	<	ForkJoinPool pool = w == null? null : w.pool;
245	>	private int externalAwaitDone() {
246		int s;
247	<	while ((s = status) >= 0) {
248	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
249	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
250	<	doAwaitDone();
251	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
252	<	adjustPoolCountsOnUnblock(pool);
253	<	break;
247	>	if ((s = status) >= 0) {
248	>	boolean interrupted = false;
249	>	synchronized (this) {
250	>	while ((s = status) >= 0) {
251	>	if (s == 0)
252	>	UNSAFE.compareAndSwapInt(this, statusOffset,
253	>	0, SIGNAL);
254	>	else {
255	>	try {
256	>	wait();
257	>	} catch (InterruptedException ie) {
258	>	interrupted = true;
259	>	}
260	>	}
261	>	}
262		}
263	+	if (interrupted)
264	+	Thread.currentThread().interrupt();
265		}
266		return s;
267		}
268
269		/**
270	<	* Timed version of awaitDone
277	<	* @return status upon exit
270	>	* Blocks a non-worker-thread until completion or interruption or timeout.
271		*/
272	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
273	<	ForkJoinPool pool = w == null? null : w.pool;
272	>	private int externalInterruptibleAwaitDone(long millis)
273	>	throws InterruptedException {
274		int s;
275	<	while ((s = status) >= 0) {
276	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
277	<	long startTime = System.nanoTime();
278	<	if (pool == null || !pool.preJoin(this, false))
279	<	doAwaitDone(startTime, nanos);
280	<	if ((s = status) >= 0) {
281	<	adjustPoolCountsOnCancelledWait(pool);
282	<	s = status;
275	>	if (Thread.interrupted())
276	>	throw new InterruptedException();
277	>	if ((s = status) >= 0) {
278	>	synchronized (this) {
279	>	while ((s = status) >= 0) {
280	>	if (s == 0)
281	>	UNSAFE.compareAndSwapInt(this, statusOffset,
282	>	0, SIGNAL);
283	>	else {
284	>	wait(millis);
285	>	if (millis > 0L)
286	>	break;
287	>	}
288		}
291	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
292	–	adjustPoolCountsOnUnblock(pool);
293	–	break;
289		}
290		}
291		return s;
292		}
293
294		/**
295	<	* Notify pool that thread is unblocked. Called by signalled
296	<	* threads when woken by non-FJ threads (which is atypical).
295	>	* Primary execution method for stolen tasks. Unless done, calls
296	>	* exec and records status if completed, but doesn't wait for
297	>	* completion otherwise.
298		*/
299	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
300	<	int s;
301	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
302	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
303	<	pool.updateRunningCount(s);
299	>	final void doExec() {
300	>	if (status >= 0) {
301	>	boolean completed;
302	>	try {
303	>	completed = exec();
304	>	} catch (Throwable rex) {
305	>	setExceptionalCompletion(rex);
306	>	return;
307	>	}
308	>	if (completed)
309	>	setCompletion(NORMAL); // must be outside try block
310	>	}
311		}
312
313		/**
314	<	* Notify pool to adjust counts on cancelled or timed out wait
314	>	* Primary mechanics for join, get, quietlyJoin.
315	>	* @return status upon completion
316		*/
317	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
318	<	if (pool != null) {
319	<	int s;
320	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
321	<	if (casStatus(s, s - 1)) {
322	<	pool.updateRunningCount(1);
323	<	break;
317	>	private int doJoin() {
318	>	Thread t; ForkJoinWorkerThread w; int s; boolean completed;
319	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
320	>	if ((s = status) < 0)
321	>	return s;
322	>	if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) {
323	>	try {
324	>	completed = exec();
325	>	} catch (Throwable rex) {
326	>	return setExceptionalCompletion(rex);
327		}
328	+	if (completed)
329	+	return setCompletion(NORMAL);
330		}
331	+	return w.joinTask(this);
332		}
333	+	else
334	+	return externalAwaitDone();
335		}
336
337		/**
338	<	* Handle interruptions during waits.
338	>	* Primary mechanics for invoke, quietlyInvoke.
339	>	* @return status upon completion
340		*/
341	<	private void onInterruptedWait() {
342	<	ForkJoinWorkerThread w = getWorker();
343	<	if (w == null)
344	<	Thread.currentThread().interrupt(); // re-interrupt
345	<	else if (w.isTerminating())
346	<	cancelIgnoringExceptions();
347	<	// else if FJworker, ignore interrupt
341	>	private int doInvoke() {
342	>	int s; boolean completed;
343	>	if ((s = status) < 0)
344	>	return s;
345	>	try {
346	>	completed = exec();
347	>	} catch (Throwable rex) {
348	>	return setExceptionalCompletion(rex);
349	>	}
350	>	if (completed)
351	>	return setCompletion(NORMAL);
352	>	else
353	>	return doJoin();
354		}
355
356	<	// Recording and reporting exceptions
356	>	// Exception table support
357
358	<	private void setDoneExceptionally(Throwable rex) {
359	<	exceptionMap.put(this, rex);
360	<	setCompletion(EXCEPTIONAL);
361	<	}
358	>	/**
359	>	* Table of exceptions thrown by tasks, to enable reporting by
360	>	* callers. Because exceptions are rare, we don't directly keep
361	>	* them with task objects, but instead use a weak ref table.  Note
362	>	* that cancellation exceptions don't appear in the table, but are
363	>	* instead recorded as status values.
364	>	*
365	>	* Note: These statics are initialized below in static block.
366	>	*/
367	>	private static final ExceptionNode[] exceptionTable;
368	>	private static final ReentrantLock exceptionTableLock;
369	>	private static final ReferenceQueue<Object> exceptionTableRefQueue;
370
371		/**
372	<	* Throws the exception associated with status s;
346	<	* @throws the exception
372	>	* Fixed capacity for exceptionTable.
373		*/
374	<	private void reportException(int s) {
349	<	if ((s &= COMPLETION_MASK) < NORMAL) {
350	<	if (s == CANCELLED)
351	<	throw new CancellationException();
352	<	else
353	<	rethrowException(exceptionMap.get(this));
354	<	}
355	<	}
374	>	private static final int EXCEPTION_MAP_CAPACITY = 32;
375
376		/**
377	<	* Returns result or throws exception using j.u.c.Future conventions
378	<	* Only call when isDone known to be true.
377	>	* Key-value nodes for exception table.  The chained hash table
378	>	* uses identity comparisons, full locking, and weak references
379	>	* for keys. The table has a fixed capacity because it only
380	>	* maintains task exceptions long enough for joiners to access
381	>	* them, so should never become very large for sustained
382	>	* periods. However, since we do not know when the last joiner
383	>	* completes, we must use weak references and expunge them. We do
384	>	* so on each operation (hence full locking). Also, some thread in
385	>	* any ForkJoinPool will call helpExpungeStaleExceptions when its
386	>	* pool becomes isQuiescent.
387		*/
388	<	private V reportFutureResult()
389	<	throws ExecutionException, InterruptedException {
390	<	int s = status & COMPLETION_MASK;
391	<	if (s < NORMAL) {
392	<	Throwable ex;
393	<	if (s == CANCELLED)
394	<	throw new CancellationException();
395	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
396	<	throw new ExecutionException(ex);
370	<	if (Thread.interrupted())
371	<	throw new InterruptedException();
388	>	static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{
389	>	final Throwable ex;
390	>	ExceptionNode next;
391	>	final long thrower;  // use id not ref to avoid weak cycles
392	>	ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
393	>	super(task, exceptionTableRefQueue);
394	>	this.ex = ex;
395	>	this.next = next;
396	>	this.thrower = Thread.currentThread().getId();
397		}
373	–	return getRawResult();
398		}
399
400		/**
401	<	* Returns result or throws exception using j.u.c.Future conventions
402	<	* with timeouts
401	>	* Records exception and sets exceptional completion.
402	>	*
403	>	* @return status on exit
404		*/
405	<	private V reportTimedFutureResult()
406	<	throws InterruptedException, ExecutionException, TimeoutException {
407	<	Throwable ex;
408	<	int s = status & COMPLETION_MASK;
409	<	if (s == NORMAL)
410	<	return getRawResult();
411	<	if (s == CANCELLED)
412	<	throw new CancellationException();
413	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
414	<	throw new ExecutionException(ex);
415	<	if (Thread.interrupted())
416	<	throw new InterruptedException();
417	<	throw new TimeoutException();
405	>	private int setExceptionalCompletion(Throwable ex) {
406	>	int h = System.identityHashCode(this);
407	>	final ReentrantLock lock = exceptionTableLock;
408	>	lock.lock();
409	>	try {
410	>	expungeStaleExceptions();
411	>	ExceptionNode[] t = exceptionTable;
412	>	int i = h & (t.length - 1);
413	>	for (ExceptionNode e = t[i]; ; e = e.next) {
414	>	if (e == null) {
415	>	t[i] = new ExceptionNode(this, ex, t[i]);
416	>	break;
417	>	}
418	>	if (e.get() == this) // already present
419	>	break;
420	>	}
421	>	} finally {
422	>	lock.unlock();
423	>	}
424	>	return setCompletion(EXCEPTIONAL);
425		}
426
395	–	// internal execution methods
396	–
427		/**
428	<	* Calls exec, recording completion, and rethrowing exception if
399	<	* encountered. Caller should normally check status before calling
400	<	* @return true if completed normally
428	>	* Removes exception node and clears status
429		*/
430	<	private boolean tryExec() {
431	<	try { // try block must contain only call to exec
432	<	if (!exec())
433	<	return false;
434	<	} catch (Throwable rex) {
435	<	setDoneExceptionally(rex);
436	<	rethrowException(rex);
437	<	return false; // not reached
430	>	private void clearExceptionalCompletion() {
431	>	int h = System.identityHashCode(this);
432	>	final ReentrantLock lock = exceptionTableLock;
433	>	lock.lock();
434	>	try {
435	>	ExceptionNode[] t = exceptionTable;
436	>	int i = h & (t.length - 1);
437	>	ExceptionNode e = t[i];
438	>	ExceptionNode pred = null;
439	>	while (e != null) {
440	>	ExceptionNode next = e.next;
441	>	if (e.get() == this) {
442	>	if (pred == null)
443	>	t[i] = next;
444	>	else
445	>	pred.next = next;
446	>	break;
447	>	}
448	>	pred = e;
449	>	e = next;
450	>	}
451	>	expungeStaleExceptions();
452	>	status = 0;
453	>	} finally {
454	>	lock.unlock();
455		}
411	–	setNormalCompletion();
412	–	return true;
456		}
457
458		/**
459	<	* Main execution method used by worker threads. Invokes
460	<	* base computation unless already complete
459	>	* Returns a rethrowable exception for the given task, if
460	>	* available. To provide accurate stack traces, if the exception
461	>	* was not thrown by the current thread, we try to create a new
462	>	* exception of the same type as the one thrown, but with the
463	>	* recorded exception as its cause. If there is no such
464	>	* constructor, we instead try to use a no-arg constructor,
465	>	* followed by initCause, to the same effect. If none of these
466	>	* apply, or any fail due to other exceptions, we return the
467	>	* recorded exception, which is still correct, although it may
468	>	* contain a misleading stack trace.
469	>	*
470	>	* @return the exception, or null if none
471		*/
472	<	final void quietlyExec() {
473	<	if (status >= 0) {
472	>	private Throwable getThrowableException() {
473	>	if (status != EXCEPTIONAL)
474	>	return null;
475	>	int h = System.identityHashCode(this);
476	>	ExceptionNode e;
477	>	final ReentrantLock lock = exceptionTableLock;
478	>	lock.lock();
479	>	try {
480	>	expungeStaleExceptions();
481	>	ExceptionNode[] t = exceptionTable;
482	>	e = t[h & (t.length - 1)];
483	>	while (e != null && e.get() != this)
484	>	e = e.next;
485	>	} finally {
486	>	lock.unlock();
487	>	}
488	>	Throwable ex;
489	>	if (e == null || (ex = e.ex) == null)
490	>	return null;
491	>	if (e.thrower != Thread.currentThread().getId()) {
492	>	Class<? extends Throwable> ec = ex.getClass();
493		try {
494	<	if (!exec())
495	<	return;
496	<	} catch(Throwable rex) {
497	<	setDoneExceptionally(rex);
498	<	return;
494	>	Constructor<?> noArgCtor = null;
495	>	Constructor<?>[] cs = ec.getConstructors();// public ctors only
496	>	for (int i = 0; i < cs.length; ++i) {
497	>	Constructor<?> c = cs[i];
498	>	Class<?>[] ps = c.getParameterTypes();
499	>	if (ps.length == 0)
500	>	noArgCtor = c;
501	>	else if (ps.length == 1 && ps[0] == Throwable.class)
502	>	return (Throwable)(c.newInstance(ex));
503	>	}
504	>	if (noArgCtor != null) {
505	>	Throwable wx = (Throwable)(noArgCtor.newInstance());
506	>	wx.initCause(ex);
507	>	return wx;
508	>	}
509	>	} catch (Exception ignore) {
510		}
428	–	setNormalCompletion();
511		}
512	+	return ex;
513		}
514
515		/**
516	<	* Calls exec, recording but not rethrowing exception
434	<	* Caller should normally check status before calling
435	<	* @return true if completed normally
516	>	* Poll stale refs and remove them. Call only while holding lock.
517		*/
518	<	private boolean tryQuietlyInvoke() {
519	<	try {
520	<	if (!exec())
521	<	return false;
522	<	} catch (Throwable rex) {
523	<	setDoneExceptionally(rex);
524	<	return false;
518	>	private static void expungeStaleExceptions() {
519	>	for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
520	>	if (x instanceof ExceptionNode) {
521	>	ForkJoinTask<?> key = ((ExceptionNode)x).get();
522	>	ExceptionNode[] t = exceptionTable;
523	>	int i = System.identityHashCode(key) & (t.length - 1);
524	>	ExceptionNode e = t[i];
525	>	ExceptionNode pred = null;
526	>	while (e != null) {
527	>	ExceptionNode next = e.next;
528	>	if (e == x) {
529	>	if (pred == null)
530	>	t[i] = next;
531	>	else
532	>	pred.next = next;
533	>	break;
534	>	}
535	>	pred = e;
536	>	e = next;
537	>	}
538	>	}
539		}
445	–	setNormalCompletion();
446	–	return true;
540		}
541
542		/**
543	<	* Cancel, ignoring any exceptions it throws
543	>	* If lock is available, poll stale refs and remove them.
544	>	* Called from ForkJoinPool when pools become quiescent.
545		*/
546	<	final void cancelIgnoringExceptions() {
547	<	try {
548	<	cancel(false);
549	<	} catch(Throwable ignore) {
546	>	static final void helpExpungeStaleExceptions() {
547	>	final ReentrantLock lock = exceptionTableLock;
548	>	if (lock.tryLock()) {
549	>	try {
550	>	expungeStaleExceptions();
551	>	} finally {
552	>	lock.unlock();
553	>	}
554		}
555		}
556
557		/**
558	<	* Main implementation of helpJoin
558	>	* Report the result of invoke or join; called only upon
559	>	* non-normal return of internal versions.
560		*/
561	<	private int busyJoin(ForkJoinWorkerThread w) {
562	<	int s;
563	<	ForkJoinTask<?> t;
564	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
565	<	t.quietlyExec();
566	<	return (s >= 0)? awaitDone(w, false) : s; // block if no work
561	>	private V reportResult() {
562	>	int s; Throwable ex;
563	>	if ((s = status) == CANCELLED)
564	>	throw new CancellationException();
565	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
566	>	UNSAFE.throwException(ex);
567	>	return getRawResult();
568		}
569
570		// public methods
#	Line 472 | Line 572 | public abstract class ForkJoinTask<V> im
572		/**
573		* Arranges to asynchronously execute this task.  While it is not
574		* necessarily enforced, it is a usage error to fork a task more
575	<	* than once unless it has completed and been reinitialized.  This
576	<	* method may be invoked only from within ForkJoinTask
577	<	* computations. Attempts to invoke in other contexts result in
578	<	* exceptions or errors possibly including ClassCastException.
575	>	* than once unless it has completed and been reinitialized.
576	>	* Subsequent modifications to the state of this task or any data
577	>	* it operates on are not necessarily consistently observable by
578	>	* any thread other than the one executing it unless preceded by a
579	>	* call to {@link #join} or related methods, or a call to {@link
580	>	* #isDone} returning {@code true}.
581	>	*
582	>	* <p>This method may be invoked only from within {@code
583	>	* ForkJoinPool} computations (as may be determined using method
584	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
585	>	* result in exceptions or errors, possibly including {@code
586	>	* ClassCastException}.
587	>	*
588	>	* @return {@code this}, to simplify usage
589		*/
590	<	public final void fork() {
591	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
590	>	public final ForkJoinTask<V> fork() {
591	>	((ForkJoinWorkerThread) Thread.currentThread())
592	>	.pushTask(this);
593	>	return this;
594		}
595
596		/**
597	<	* Returns the result of the computation when it is ready.
598	<	* This method differs from <code>get</code> in that abnormal
599	<	* completion results in RuntimeExceptions or Errors, not
600	<	* ExecutionExceptions.
597	>	* Returns the result of the computation when it {@link #isDone is
598	>	* done}.  This method differs from {@link #get()} in that
599	>	* abnormal completion results in {@code RuntimeException} or
600	>	* {@code Error}, not {@code ExecutionException}, and that
601	>	* interrupts of the calling thread do <em>not</em> cause the
602	>	* method to abruptly return by throwing {@code
603	>	* InterruptedException}.
604		*
605		* @return the computed result
606		*/
607		public final V join() {
608	<	ForkJoinWorkerThread w = getWorker();
609	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
610	<	reportException(awaitDone(w, true));
611	<	return getRawResult();
608	>	if (doJoin() != NORMAL)
609	>	return reportResult();
610	>	else
611	>	return getRawResult();
612		}
613
614		/**
615		* Commences performing this task, awaits its completion if
616	<	* necessary, and return its result.
617	<	* @throws Throwable (a RuntimeException, Error, or unchecked
618	<	* exception) if the underlying computation did so.
616	>	* necessary, and returns its result, or throws an (unchecked)
617	>	* {@code RuntimeException} or {@code Error} if the underlying
618	>	* computation did so.
619	>	*
620		* @return the computed result
621		*/
622		public final V invoke() {
623	<	if (status >= 0 && tryExec())
624	<	return getRawResult();
623	>	if (doInvoke() != NORMAL)
624	>	return reportResult();
625		else
626	<	return join();
626	>	return getRawResult();
627		}
628
629		/**
630	<	* Forks both tasks, returning when <code>isDone</code> holds for
631	<	* both of them or an exception is encountered. This method may be
632	<	* invoked only from within ForkJoinTask computations. Attempts to
633	<	* invoke in other contexts result in exceptions or errors
634	<	* possibly including ClassCastException.
635	<	* @param t1 one task
636	<	* @param t2 the other task
637	<	* @throws NullPointerException if t1 or t2 are null
638	<	* @throws RuntimeException or Error if either task did so.
630	>	* Forks the given tasks, returning when {@code isDone} holds for
631	>	* each task or an (unchecked) exception is encountered, in which
632	>	* case the exception is rethrown. If more than one task
633	>	* encounters an exception, then this method throws any one of
634	>	* these exceptions. If any task encounters an exception, the
635	>	* other may be cancelled. However, the execution status of
636	>	* individual tasks is not guaranteed upon exceptional return. The
637	>	* status of each task may be obtained using {@link
638	>	* #getException()} and related methods to check if they have been
639	>	* cancelled, completed normally or exceptionally, or left
640	>	* unprocessed.
641	>	*
642	>	* <p>This method may be invoked only from within {@code
643	>	* ForkJoinPool} computations (as may be determined using method
644	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
645	>	* result in exceptions or errors, possibly including {@code
646	>	* ClassCastException}.
647	>	*
648	>	* @param t1 the first task
649	>	* @param t2 the second task
650	>	* @throws NullPointerException if any task is null
651		*/
652	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
652	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
653		t2.fork();
654		t1.invoke();
655		t2.join();
656		}
657
658		/**
659	<	* Forks the given tasks, returning when <code>isDone</code> holds
660	<	* for all of them. If any task encounters an exception, others
661	<	* may be cancelled.  This method may be invoked only from within
662	<	* ForkJoinTask computations. Attempts to invoke in other contexts
663	<	* result in exceptions or errors possibly including ClassCastException.
664	<	* @param tasks the array of tasks
665	<	* @throws NullPointerException if tasks or any element are null.
666	<	* @throws RuntimeException or Error if any task did so.
659	>	* Forks the given tasks, returning when {@code isDone} holds for
660	>	* each task or an (unchecked) exception is encountered, in which
661	>	* case the exception is rethrown. If more than one task
662	>	* encounters an exception, then this method throws any one of
663	>	* these exceptions. If any task encounters an exception, others
664	>	* may be cancelled. However, the execution status of individual
665	>	* tasks is not guaranteed upon exceptional return. The status of
666	>	* each task may be obtained using {@link #getException()} and
667	>	* related methods to check if they have been cancelled, completed
668	>	* normally or exceptionally, or left unprocessed.
669	>	*
670	>	* <p>This method may be invoked only from within {@code
671	>	* ForkJoinPool} computations (as may be determined using method
672	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
673	>	* result in exceptions or errors, possibly including {@code
674	>	* ClassCastException}.
675	>	*
676	>	* @param tasks the tasks
677	>	* @throws NullPointerException if any task is null
678		*/
679		public static void invokeAll(ForkJoinTask<?>... tasks) {
680		Throwable ex = null;
#	Line 548 | Line 687 | public abstract class ForkJoinTask<V> im
687		}
688		else if (i != 0)
689		t.fork();
690	<	else {
691	<	t.quietlyInvoke();
553	<	if (ex == null)
554	<	ex = t.getException();
555	<	}
690	>	else if (t.doInvoke() < NORMAL && ex == null)
691	>	ex = t.getException();
692		}
693		for (int i = 1; i <= last; ++i) {
694		ForkJoinTask<?> t = tasks[i];
695		if (t != null) {
696		if (ex != null)
697		t.cancel(false);
698	<	else {
699	<	t.quietlyJoin();
564	<	if (ex == null)
565	<	ex = t.getException();
566	<	}
698	>	else if (t.doJoin() < NORMAL)
699	>	ex = t.getException();
700		}
701		}
702		if (ex != null)
703	<	rethrowException(ex);
703	>	UNSAFE.throwException(ex);
704		}
705
706		/**
707	<	* Forks all tasks in the collection, returning when
708	<	* <code>isDone</code> holds for all of them. If any task
709	<	* encounters an exception, others may be cancelled.  This method
710	<	* may be invoked only from within ForkJoinTask
711	<	* computations. Attempts to invoke in other contexts resul!t in
712	<	* exceptions or errors possibly including ClassCastException.
707	>	* Forks all tasks in the specified collection, returning when
708	>	* {@code isDone} holds for each task or an (unchecked) exception
709	>	* is encountered, in which case the exception is rethrown. If
710	>	* more than one task encounters an exception, then this method
711	>	* throws any one of these exceptions. If any task encounters an
712	>	* exception, others may be cancelled. However, the execution
713	>	* status of individual tasks is not guaranteed upon exceptional
714	>	* return. The status of each task may be obtained using {@link
715	>	* #getException()} and related methods to check if they have been
716	>	* cancelled, completed normally or exceptionally, or left
717	>	* unprocessed.
718	>	*
719	>	* <p>This method may be invoked only from within {@code
720	>	* ForkJoinPool} computations (as may be determined using method
721	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
722	>	* result in exceptions or errors, possibly including {@code
723	>	* ClassCastException}.
724	>	*
725		* @param tasks the collection of tasks
726	<	* @throws NullPointerException if tasks or any element are null.
727	<	* @throws RuntimeException or Error if any task did so.
726	>	* @return the tasks argument, to simplify usage
727	>	* @throws NullPointerException if tasks or any element are null
728		*/
729	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
730	<	if (!(tasks instanceof List)) {
731	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
732	<	return;
729	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
730	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
731	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
732	>	return tasks;
733		}
734	+	@SuppressWarnings("unchecked")
735		List<? extends ForkJoinTask<?>> ts =
736	<	(List<? extends ForkJoinTask<?>>)tasks;
736	>	(List<? extends ForkJoinTask<?>>) tasks;
737		Throwable ex = null;
738		int last = ts.size() - 1;
739		for (int i = last; i >= 0; --i) {
#	Line 598 | Line 744 | public abstract class ForkJoinTask<V> im
744		}
745		else if (i != 0)
746		t.fork();
747	<	else {
748	<	t.quietlyInvoke();
603	<	if (ex == null)
604	<	ex = t.getException();
605	<	}
747	>	else if (t.doInvoke() < NORMAL && ex == null)
748	>	ex = t.getException();
749		}
750		for (int i = 1; i <= last; ++i) {
751		ForkJoinTask<?> t = ts.get(i);
752		if (t != null) {
753		if (ex != null)
754		t.cancel(false);
755	<	else {
756	<	t.quietlyJoin();
614	<	if (ex == null)
615	<	ex = t.getException();
616	<	}
755	>	else if (t.doJoin() < NORMAL)
756	>	ex = t.getException();
757		}
758		}
759		if (ex != null)
760	<	rethrowException(ex);
760	>	UNSAFE.throwException(ex);
761	>	return tasks;
762		}
763
764		/**
765	<	* Returns true if the computation performed by this task has
766	<	* completed (or has been cancelled).
767	<	* @return true if this computation has completed
765	>	* Attempts to cancel execution of this task. This attempt will
766	>	* fail if the task has already completed or could not be
767	>	* cancelled for some other reason. If successful, and this task
768	>	* has not started when {@code cancel} is called, execution of
769	>	* this task is suppressed. After this method returns
770	>	* successfully, unless there is an intervening call to {@link
771	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
772	>	* {@link #isDone}, and {@code cancel} will return {@code true}
773	>	* and calls to {@link #join} and related methods will result in
774	>	* {@code CancellationException}.
775	>	*
776	>	* <p>This method may be overridden in subclasses, but if so, must
777	>	* still ensure that these properties hold. In particular, the
778	>	* {@code cancel} method itself must not throw exceptions.
779	>	*
780	>	* <p>This method is designed to be invoked by <em>other</em>
781	>	* tasks. To terminate the current task, you can just return or
782	>	* throw an unchecked exception from its computation method, or
783	>	* invoke {@link #completeExceptionally}.
784	>	*
785	>	* @param mayInterruptIfRunning this value has no effect in the
786	>	* default implementation because interrupts are not used to
787	>	* control cancellation.
788	>	*
789	>	* @return {@code true} if this task is now cancelled
790		*/
791	<	public final boolean isDone() {
792	<	return status < 0;
791	>	public boolean cancel(boolean mayInterruptIfRunning) {
792	>	return setCompletion(CANCELLED) == CANCELLED;
793		}
794
795		/**
796	<	* Returns true if this task was cancelled.
797	<	* @return true if this task was cancelled
796	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
797	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
798	>	* exceptions, but if it does anyway, we have no recourse during
799	>	* shutdown, so guard against this case.
800		*/
801	+	final void cancelIgnoringExceptions() {
802	+	try {
803	+	cancel(false);
804	+	} catch (Throwable ignore) {
805	+	}
806	+	}
807	+
808	+	public final boolean isDone() {
809	+	return status < 0;
810	+	}
811	+
812		public final boolean isCancelled() {
813	<	return (status & COMPLETION_MASK) == CANCELLED;
813	>	return status == CANCELLED;
814		}
815
816		/**
817	<	* Asserts that the results of this task's computation will not be
642	<	* used. If a cancellation occurs before atempting to execute this
643	<	* task, then execution will be suppressed, <code>isCancelled</code>
644	<	* will report true, and <code>join</code> will result in a
645	<	* <code>CancellationException</code> being thrown. Otherwise, when
646	<	* cancellation races with completion, there are no guarantees
647	<	* about whether <code>isCancelled</code> will report true, whether
648	<	* <code>join</code> will return normally or via an exception, or
649	<	* whether these behaviors will remain consistent upon repeated
650	<	* invocation.
817	>	* Returns {@code true} if this task threw an exception or was cancelled.
818		*
819	<	* <p>This method may be overridden in subclasses, but if so, must
653	<	* still ensure that these minimal properties hold. In particular,
654	<	* the cancel method itself must not throw exceptions.
655	<	*
656	<	* <p> This method is designed to be invoked by <em>other</em>
657	<	* tasks. To terminate the current task, you can just return or
658	<	* throw an unchecked exception from its computation method, or
659	<	* invoke <code>completeExceptionally</code>.
660	<	*
661	<	* @param mayInterruptIfRunning this value is ignored in the
662	<	* default implementation because tasks are not in general
663	<	* cancelled via interruption.
664	<	*
665	<	* @return true if this task is now cancelled
819	>	* @return {@code true} if this task threw an exception or was cancelled
820		*/
821	<	public boolean cancel(boolean mayInterruptIfRunning) {
822	<	setCompletion(CANCELLED);
669	<	return (status & COMPLETION_MASK) == CANCELLED;
821	>	public final boolean isCompletedAbnormally() {
822	>	return status < NORMAL;
823		}
824
825		/**
826	<	* Returns true if this task threw an exception or was cancelled
827	<	* @return true if this task threw an exception or was cancelled
826	>	* Returns {@code true} if this task completed without throwing an
827	>	* exception and was not cancelled.
828	>	*
829	>	* @return {@code true} if this task completed without throwing an
830	>	* exception and was not cancelled
831		*/
832	<	public final boolean isCompletedAbnormally() {
833	<	return (status & COMPLETION_MASK) < NORMAL;
832	>	public final boolean isCompletedNormally() {
833	>	return status == NORMAL;
834		}
835
836		/**
837		* Returns the exception thrown by the base computation, or a
838	<	* CancellationException if cancelled, or null if none or if the
839	<	* method has not yet completed.
840	<	* @return the exception, or null if none
838	>	* {@code CancellationException} if cancelled, or {@code null} if
839	>	* none or if the method has not yet completed.
840	>	*
841	>	* @return the exception, or {@code null} if none
842		*/
843		public final Throwable getException() {
844	<	int s = status & COMPLETION_MASK;
845	<	if (s >= NORMAL)
846	<	return null;
847	<	if (s == CANCELLED)
691	<	return new CancellationException();
692	<	return exceptionMap.get(this);
844	>	int s = status;
845	>	return ((s >= NORMAL)    ? null :
846	>	(s == CANCELLED) ? new CancellationException() :
847	>	getThrowableException());
848		}
849
850		/**
851		* Completes this task abnormally, and if not already aborted or
852		* cancelled, causes it to throw the given exception upon
853	<	* <code>join</code> and related operations. This method may be used
853	>	* {@code join} and related operations. This method may be used
854		* to induce exceptions in asynchronous tasks, or to force
855		* completion of tasks that would not otherwise complete.  Its use
856	<	* in other situations is likely to be wrong.  This method is
857	<	* overridable, but overridden versions must invoke <code>super</code>
856	>	* in other situations is discouraged.  This method is
857	>	* overridable, but overridden versions must invoke {@code super}
858		* implementation to maintain guarantees.
859		*
860	<	* @param ex the exception to throw. If this exception is
861	<	* not a RuntimeException or Error, the actual exception thrown
862	<	* will be a RuntimeException with cause ex.
860	>	* @param ex the exception to throw. If this exception is not a
861	>	* {@code RuntimeException} or {@code Error}, the actual exception
862	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
863		*/
864		public void completeExceptionally(Throwable ex) {
865	<	setDoneExceptionally((ex instanceof RuntimeException) ||
866	<	(ex instanceof Error)? ex :
867	<	new RuntimeException(ex));
865	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
866	>	(ex instanceof Error) ? ex :
867	>	new RuntimeException(ex));
868		}
869
870		/**
871		* Completes this task, and if not already aborted or cancelled,
872	<	* returning a <code>null</code> result upon <code>join</code> and related
873	<	* operations. This method may be used to provide results for
874	<	* asynchronous tasks, or to provide alternative handling for
875	<	* tasks that would not otherwise complete normally. Its use in
876	<	* other situations is likely to be wrong. This method is
877	<	* overridable, but overridden versions must invoke <code>super</code>
878	<	* implementation to maintain guarantees.
872	>	* returning the given value as the result of subsequent
873	>	* invocations of {@code join} and related operations. This method
874	>	* may be used to provide results for asynchronous tasks, or to
875	>	* provide alternative handling for tasks that would not otherwise
876	>	* complete normally. Its use in other situations is
877	>	* discouraged. This method is overridable, but overridden
878	>	* versions must invoke {@code super} implementation to maintain
879	>	* guarantees.
880		*
881	<	* @param value the result value for this task.
881	>	* @param value the result value for this task
882		*/
883		public void complete(V value) {
884		try {
885		setRawResult(value);
886	<	} catch(Throwable rex) {
887	<	setDoneExceptionally(rex);
886	>	} catch (Throwable rex) {
887	>	setExceptionalCompletion(rex);
888		return;
889		}
890	<	setNormalCompletion();
735	<	}
736	<
737	<	public final V get() throws InterruptedException, ExecutionException {
738	<	ForkJoinWorkerThread w = getWorker();
739	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
740	<	awaitDone(w, true);
741	<	return reportFutureResult();
742	<	}
743	<
744	<	public final V get(long timeout, TimeUnit unit)
745	<	throws InterruptedException, ExecutionException, TimeoutException {
746	<	ForkJoinWorkerThread w = getWorker();
747	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
748	<	awaitDone(w, unit.toNanos(timeout));
749	<	return reportTimedFutureResult();
890	>	setCompletion(NORMAL);
891		}
892
893		/**
894	<	* Possibly executes other tasks until this task is ready, then
895	<	* returns the result of the computation.  This method may be more
896	<	* efficient than <code>join</code>, but is only applicable when
756	<	* there are no potemtial dependencies between continuation of the
757	<	* current task and that of any other task that might be executed
758	<	* while helping. (This usually holds for pure divide-and-conquer
759	<	* tasks). This method may be invoked only from within
760	<	* ForkJoinTask computations. Attempts to invoke in other contexts
761	<	* resul!t in exceptions or errors possibly including ClassCastException.
894	>	* Waits if necessary for the computation to complete, and then
895	>	* retrieves its result.
896	>	*
897		* @return the computed result
898	+	* @throws CancellationException if the computation was cancelled
899	+	* @throws ExecutionException if the computation threw an
900	+	* exception
901	+	* @throws InterruptedException if the current thread is not a
902	+	* member of a ForkJoinPool and was interrupted while waiting
903		*/
904	<	public final V helpJoin() {
905	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
906	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
907	<	reportException(busyJoin(w));
904	>	public final V get() throws InterruptedException, ExecutionException {
905	>	int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ?
906	>	doJoin() : externalInterruptibleAwaitDone(0L);
907	>	Throwable ex;
908	>	if (s == CANCELLED)
909	>	throw new CancellationException();
910	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
911	>	throw new ExecutionException(ex);
912		return getRawResult();
913		}
914
915		/**
916	<	* Possibly executes other tasks until this task is ready.  This
917	<	* method may be invoked only from within ForkJoinTask
918	<	* computations. Attempts to invoke in other contexts resul!t in
919	<	* exceptions or errors possibly including ClassCastException.
916	>	* Waits if necessary for at most the given time for the computation
917	>	* to complete, and then retrieves its result, if available.
918	>	*
919	>	* @param timeout the maximum time to wait
920	>	* @param unit the time unit of the timeout argument
921	>	* @return the computed result
922	>	* @throws CancellationException if the computation was cancelled
923	>	* @throws ExecutionException if the computation threw an
924	>	* exception
925	>	* @throws InterruptedException if the current thread is not a
926	>	* member of a ForkJoinPool and was interrupted while waiting
927	>	* @throws TimeoutException if the wait timed out
928		*/
929	<	public final void quietlyHelpJoin() {
930	<	if (status >= 0) {
931	<	ForkJoinWorkerThread w =
932	<	(ForkJoinWorkerThread)(Thread.currentThread());
933	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
934	<	busyJoin(w);
929	>	public final V get(long timeout, TimeUnit unit)
930	>	throws InterruptedException, ExecutionException, TimeoutException {
931	>	Thread t = Thread.currentThread();
932	>	if (t instanceof ForkJoinWorkerThread) {
933	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
934	>	long nanos = unit.toNanos(timeout);
935	>	if (status >= 0) {
936	>	boolean completed = false;
937	>	if (w.unpushTask(this)) {
938	>	try {
939	>	completed = exec();
940	>	} catch (Throwable rex) {
941	>	setExceptionalCompletion(rex);
942	>	}
943	>	}
944	>	if (completed)
945	>	setCompletion(NORMAL);
946	>	else if (status >= 0 && nanos > 0)
947	>	w.pool.timedAwaitJoin(this, nanos);
948	>	}
949	>	}
950	>	else {
951	>	long millis = unit.toMillis(timeout);
952	>	if (millis > 0)
953	>	externalInterruptibleAwaitDone(millis);
954	>	}
955	>	int s = status;
956	>	if (s != NORMAL) {
957	>	Throwable ex;
958	>	if (s == CANCELLED)
959	>	throw new CancellationException();
960	>	if (s != EXCEPTIONAL)
961	>	throw new TimeoutException();
962	>	if ((ex = getThrowableException()) != null)
963	>	throw new ExecutionException(ex);
964		}
965	+	return getRawResult();
966		}
967
968		/**
969	<	* Joins this task, without returning its result or throwing an
969	>	* Joins this task, without returning its result or throwing its
970		* exception. This method may be useful when processing
971		* collections of tasks when some have been cancelled or otherwise
972		* known to have aborted.
973		*/
974		public final void quietlyJoin() {
975	<	if (status >= 0) {
794	<	ForkJoinWorkerThread w = getWorker();
795	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
796	<	awaitDone(w, true);
797	<	}
975	>	doJoin();
976		}
977
978		/**
979		* Commences performing this task and awaits its completion if
980	<	* necessary, without returning its result or throwing an
981	<	* exception. This method may be useful when processing
804	<	* collections of tasks when some have been cancelled or otherwise
805	<	* known to have aborted.
980	>	* necessary, without returning its result or throwing its
981	>	* exception.
982		*/
983		public final void quietlyInvoke() {
984	<	if (status >= 0 && !tryQuietlyInvoke())
809	<	quietlyJoin();
984	>	doInvoke();
985		}
986
987		/**
988		* Possibly executes tasks until the pool hosting the current task
989	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
990	<	* designs in which many tasks are forked, but none are explicitly
991	<	* joined, instead executing them until all are processed.
989	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
990	>	* be of use in designs in which many tasks are forked, but none
991	>	* are explicitly joined, instead executing them until all are
992	>	* processed.
993	>	*
994	>	* <p>This method may be invoked only from within {@code
995	>	* ForkJoinPool} computations (as may be determined using method
996	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
997	>	* result in exceptions or errors, possibly including {@code
998	>	* ClassCastException}.
999		*/
1000		public static void helpQuiesce() {
1001	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1002	<	helpQuiescePool();
1001	>	((ForkJoinWorkerThread) Thread.currentThread())
1002	>	.helpQuiescePool();
1003		}
1004
1005		/**
1006		* Resets the internal bookkeeping state of this task, allowing a
1007	<	* subsequent <code>fork</code>. This method allows repeated reuse of
1007	>	* subsequent {@code fork}. This method allows repeated reuse of
1008		* this task, but only if reuse occurs when this task has either
1009		* never been forked, or has been forked, then completed and all
1010		* outstanding joins of this task have also completed. Effects
1011	<	* under any other usage conditions are not guaranteed, and are
1012	<	* almost surely wrong. This method may be useful when executing
1011	>	* under any other usage conditions are not guaranteed.
1012	>	* This method may be useful when executing
1013		* pre-constructed trees of subtasks in loops.
1014	+	*
1015	+	* <p>Upon completion of this method, {@code isDone()} reports
1016	+	* {@code false}, and {@code getException()} reports {@code
1017	+	* null}. However, the value returned by {@code getRawResult} is
1018	+	* unaffected. To clear this value, you can invoke {@code
1019	+	* setRawResult(null)}.
1020		*/
1021		public void reinitialize() {
1022	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
1023	<	exceptionMap.remove(this);
1024	<	status = 0;
1022	>	if (status == EXCEPTIONAL)
1023	>	clearExceptionalCompletion();
1024	>	else
1025	>	status = 0;
1026		}
1027
1028		/**
1029		* Returns the pool hosting the current task execution, or null
1030	<	* if this task is executing outside of any pool.
1031	<	* @return the pool, or null if none.
1030	>	* if this task is executing outside of any ForkJoinPool.
1031	>	*
1032	>	* @see #inForkJoinPool
1033	>	* @return the pool, or {@code null} if none
1034		*/
1035		public static ForkJoinPool getPool() {
1036		Thread t = Thread.currentThread();
1037	<	return ((t instanceof ForkJoinWorkerThread)?
1038	<	((ForkJoinWorkerThread)t).pool : null);
1037	>	return (t instanceof ForkJoinWorkerThread) ?
1038	>	((ForkJoinWorkerThread) t).pool : null;
1039	>	}
1040	>
1041	>	/**
1042	>	* Returns {@code true} if the current thread is a {@link
1043	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
1044	>	*
1045	>	* @return {@code true} if the current thread is a {@link
1046	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
1047	>	* or {@code false} otherwise
1048	>	*/
1049	>	public static boolean inForkJoinPool() {
1050	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
1051		}
1052
1053		/**
#	Line 853 | Line 1056 | public abstract class ForkJoinTask<V> im
1056		* by the current thread, and has not commenced executing in
1057		* another thread.  This method may be useful when arranging
1058		* alternative local processing of tasks that could have been, but
1059	<	* were not, stolen. This method may be invoked only from within
1060	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1061	<	* result in exceptions or errors possibly including ClassCastException.
1062	<	* @return true if unforked
1059	>	* were not, stolen.
1060	>	*
1061	>	* <p>This method may be invoked only from within {@code
1062	>	* ForkJoinPool} computations (as may be determined using method
1063	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1064	>	* result in exceptions or errors, possibly including {@code
1065	>	* ClassCastException}.
1066	>	*
1067	>	* @return {@code true} if unforked
1068		*/
1069		public boolean tryUnfork() {
1070	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
1070	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1071	>	.unpushTask(this);
1072		}
1073
1074		/**
#	Line 867 | Line 1076 | public abstract class ForkJoinTask<V> im
1076		* forked by the current worker thread but not yet executed. This
1077		* value may be useful for heuristic decisions about whether to
1078		* fork other tasks.
1079	+	*
1080	+	* <p>This method may be invoked only from within {@code
1081	+	* ForkJoinPool} computations (as may be determined using method
1082	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1083	+	* result in exceptions or errors, possibly including {@code
1084	+	* ClassCastException}.
1085	+	*
1086		* @return the number of tasks
1087		*/
1088		public static int getQueuedTaskCount() {
1089	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).
1090	<	getQueueSize();
1089	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1090	>	.getQueueSize();
1091		}
1092
1093		/**
1094	<	* Returns a estimate of how many more locally queued tasks are
1094	>	* Returns an estimate of how many more locally queued tasks are
1095		* held by the current worker thread than there are other worker
1096		* threads that might steal them.  This value may be useful for
1097		* heuristic decisions about whether to fork other tasks. In many
#	Line 883 | Line 1099 | public abstract class ForkJoinTask<V> im
1099		* aim to maintain a small constant surplus (for example, 3) of
1100		* tasks, and to process computations locally if this threshold is
1101		* exceeded.
1102	+	*
1103	+	* <p>This method may be invoked only from within {@code
1104	+	* ForkJoinPool} computations (as may be determined using method
1105	+	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1106	+	* result in exceptions or errors, possibly including {@code
1107	+	* ClassCastException}.
1108	+	*
1109		* @return the surplus number of tasks, which may be negative
1110		*/
1111		public static int getSurplusQueuedTaskCount() {
1112	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
1112	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1113		.getEstimatedSurplusTaskCount();
1114		}
1115
1116		// Extension methods
1117
1118		/**
1119	<	* Returns the result that would be returned by <code>join</code>,
1120	<	* even if this task completed abnormally, or null if this task is
1121	<	* not known to have been completed.  This method is designed to
1122	<	* aid debugging, as well as to support extensions. Its use in any
1123	<	* other context is discouraged.
1119	>	* Returns the result that would be returned by {@link #join}, even
1120	>	* if this task completed abnormally, or {@code null} if this task
1121	>	* is not known to have been completed.  This method is designed
1122	>	* to aid debugging, as well as to support extensions. Its use in
1123	>	* any other context is discouraged.
1124		*
1125	<	* @return the result, or null if not completed.
1125	>	* @return the result, or {@code null} if not completed
1126		*/
1127		public abstract V getRawResult();
1128
#	Line 918 | Line 1141 | public abstract class ForkJoinTask<V> im
1141		* called otherwise. The return value controls whether this task
1142		* is considered to be done normally. It may return false in
1143		* asynchronous actions that require explicit invocations of
1144	<	* <code>complete</code> to become joinable. It may throw exceptions
1145	<	* to indicate abnormal exit.
1146	<	* @return true if completed normally
1147	<	* @throws Error or RuntimeException if encountered during computation
1144	>	* {@link #complete} to become joinable. It may also throw an
1145	>	* (unchecked) exception to indicate abnormal exit.
1146	>	*
1147	>	* @return {@code true} if completed normally
1148		*/
1149		protected abstract boolean exec();
1150
1151		/**
1152	<	* Returns, but does not unschedule or execute, the task queued by
1153	<	* the current thread but not yet executed, if one is
1152	>	* Returns, but does not unschedule or execute, a task queued by
1153	>	* the current thread but not yet executed, if one is immediately
1154		* available. There is no guarantee that this task will actually
1155	<	* be polled or executed next.  This method is designed primarily
1156	<	* to support extensions, and is unlikely to be useful otherwise.
1157	<	* This method may be invoked only from within ForkJoinTask
1158	<	* computations. Attempts to invoke in other contexts result in
1159	<	* exceptions or errors possibly including ClassCastException.
1155	>	* be polled or executed next. Conversely, this method may return
1156	>	* null even if a task exists but cannot be accessed without
1157	>	* contention with other threads.  This method is designed
1158	>	* primarily to support extensions, and is unlikely to be useful
1159	>	* otherwise.
1160	>	*
1161	>	* <p>This method may be invoked only from within {@code
1162	>	* ForkJoinPool} computations (as may be determined using method
1163	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1164	>	* result in exceptions or errors, possibly including {@code
1165	>	* ClassCastException}.
1166		*
1167	<	* @return the next task, or null if none are available
1167	>	* @return the next task, or {@code null} if none are available
1168		*/
1169		protected static ForkJoinTask<?> peekNextLocalTask() {
1170	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask();
1170	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1171	>	.peekTask();
1172		}
1173
1174		/**
1175		* Unschedules and returns, without executing, the next task
1176		* queued by the current thread but not yet executed.  This method
1177		* is designed primarily to support extensions, and is unlikely to
1178	<	* be useful otherwise.  This method may be invoked only from
949	<	* within ForkJoinTask computations. Attempts to invoke in other
950	<	* contexts result in exceptions or errors possibly including
951	<	* ClassCastException.
1178	>	* be useful otherwise.
1179		*
1180	<	* @return the next task, or null if none are available
1180	>	* <p>This method may be invoked only from within {@code
1181	>	* ForkJoinPool} computations (as may be determined using method
1182	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1183	>	* result in exceptions or errors, possibly including {@code
1184	>	* ClassCastException}.
1185	>	*
1186	>	* @return the next task, or {@code null} if none are available
1187		*/
1188		protected static ForkJoinTask<?> pollNextLocalTask() {
1189	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask();
1189	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1190	>	.pollLocalTask();
1191		}
1192
1193		/**
#	Line 961 | Line 1195 | public abstract class ForkJoinTask<V> im
1195		* queued by the current thread but not yet executed, if one is
1196		* available, or if not available, a task that was forked by some
1197		* other thread, if available. Availability may be transient, so a
1198	<	* <code>null</code> result does not necessarily imply quiecence
1198	>	* {@code null} result does not necessarily imply quiescence
1199		* of the pool this task is operating in.  This method is designed
1200		* primarily to support extensions, and is unlikely to be useful
1201	<	* otherwise.  This method may be invoked only from within
1202	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1203	<	* result in exceptions or errors possibly including
1204	<	* ClassCastException.
1201	>	* otherwise.
1202	>	*
1203	>	* <p>This method may be invoked only from within {@code
1204	>	* ForkJoinPool} computations (as may be determined using method
1205	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1206	>	* result in exceptions or errors, possibly including {@code
1207	>	* ClassCastException}.
1208		*
1209	<	* @return a task, or null if none are available
1209	>	* @return a task, or {@code null} if none are available
1210		*/
1211		protected static ForkJoinTask<?> pollTask() {
1212	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).
1213	<	pollTask();
1212	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1213	>	.pollTask();
1214	>	}
1215	>
1216	>	/**
1217	>	* Adaptor for Runnables. This implements RunnableFuture
1218	>	* to be compliant with AbstractExecutorService constraints
1219	>	* when used in ForkJoinPool.
1220	>	*/
1221	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1222	>	implements RunnableFuture<T> {
1223	>	final Runnable runnable;
1224	>	final T resultOnCompletion;
1225	>	T result;
1226	>	AdaptedRunnable(Runnable runnable, T result) {
1227	>	if (runnable == null) throw new NullPointerException();
1228	>	this.runnable = runnable;
1229	>	this.resultOnCompletion = result;
1230	>	}
1231	>	public T getRawResult() { return result; }
1232	>	public void setRawResult(T v) { result = v; }
1233	>	public boolean exec() {
1234	>	runnable.run();
1235	>	result = resultOnCompletion;
1236	>	return true;
1237	>	}
1238	>	public void run() { invoke(); }
1239	>	private static final long serialVersionUID = 5232453952276885070L;
1240	>	}
1241	>
1242	>	/**
1243	>	* Adaptor for Callables
1244	>	*/
1245	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1246	>	implements RunnableFuture<T> {
1247	>	final Callable<? extends T> callable;
1248	>	T result;
1249	>	AdaptedCallable(Callable<? extends T> callable) {
1250	>	if (callable == null) throw new NullPointerException();
1251	>	this.callable = callable;
1252	>	}
1253	>	public T getRawResult() { return result; }
1254	>	public void setRawResult(T v) { result = v; }
1255	>	public boolean exec() {
1256	>	try {
1257	>	result = callable.call();
1258	>	return true;
1259	>	} catch (Error err) {
1260	>	throw err;
1261	>	} catch (RuntimeException rex) {
1262	>	throw rex;
1263	>	} catch (Exception ex) {
1264	>	throw new RuntimeException(ex);
1265	>	}
1266	>	}
1267	>	public void run() { invoke(); }
1268	>	private static final long serialVersionUID = 2838392045355241008L;
1269	>	}
1270	>
1271	>	/**
1272	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1273	>	* method of the given {@code Runnable} as its action, and returns
1274	>	* a null result upon {@link #join}.
1275	>	*
1276	>	* @param runnable the runnable action
1277	>	* @return the task
1278	>	*/
1279	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1280	>	return new AdaptedRunnable<Void>(runnable, null);
1281	>	}
1282	>
1283	>	/**
1284	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1285	>	* method of the given {@code Runnable} as its action, and returns
1286	>	* the given result upon {@link #join}.
1287	>	*
1288	>	* @param runnable the runnable action
1289	>	* @param result the result upon completion
1290	>	* @return the task
1291	>	*/
1292	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1293	>	return new AdaptedRunnable<T>(runnable, result);
1294	>	}
1295	>
1296	>	/**
1297	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1298	>	* method of the given {@code Callable} as its action, and returns
1299	>	* its result upon {@link #join}, translating any checked exceptions
1300	>	* encountered into {@code RuntimeException}.
1301	>	*
1302	>	* @param callable the callable action
1303	>	* @return the task
1304	>	*/
1305	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1306	>	return new AdaptedCallable<T>(callable);
1307		}
1308
1309		// Serialization support
#	Line 981 | Line 1311 | public abstract class ForkJoinTask<V> im
1311		private static final long serialVersionUID = -7721805057305804111L;
1312
1313		/**
1314	<	* Save the state to a stream.
1314	>	* Saves the state to a stream (that is, serializes it).
1315		*
1316		* @serialData the current run status and the exception thrown
1317	<	* during execution, or null if none.
1317	>	* during execution, or {@code null} if none
1318		* @param s the stream
1319		*/
1320		private void writeObject(java.io.ObjectOutputStream s)
#	Line 994 | Line 1324 | public abstract class ForkJoinTask<V> im
1324		}
1325
1326		/**
1327	<	* Reconstitute the instance from a stream.
1327	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1328	>	*
1329		* @param s the stream
1330		*/
1331		private void readObject(java.io.ObjectInputStream s)
1332		throws java.io.IOException, ClassNotFoundException {
1333		s.defaultReadObject();
1003	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1004	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1334		Object ex = s.readObject();
1335		if (ex != null)
1336	<	setDoneExceptionally((Throwable)ex);
1336	>	setExceptionalCompletion((Throwable)ex);
1337		}
1338
1339	<	// Temporary Unsafe mechanics for preliminary release
1340	<	private static Unsafe getUnsafe() throws Throwable {
1339	>	// Unsafe mechanics
1340	>	private static final sun.misc.Unsafe UNSAFE;
1341	>	private static final long statusOffset;
1342	>	static {
1343	>	exceptionTableLock = new ReentrantLock();
1344	>	exceptionTableRefQueue = new ReferenceQueue<Object>();
1345	>	exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY];
1346		try {
1347	<	return Unsafe.getUnsafe();
1347	>	UNSAFE = getUnsafe();
1348	>	statusOffset = UNSAFE.objectFieldOffset
1349	>	(ForkJoinTask.class.getDeclaredField("status"));
1350	>	} catch (Exception e) {
1351	>	throw new Error(e);
1352	>	}
1353	>	}
1354	>
1355	>	/**
1356	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1357	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1358	>	* into a jdk.
1359	>	*
1360	>	* @return a sun.misc.Unsafe
1361	>	*/
1362	>	private static sun.misc.Unsafe getUnsafe() {
1363	>	try {
1364	>	return sun.misc.Unsafe.getUnsafe();
1365		} catch (SecurityException se) {
1366		try {
1367		return java.security.AccessController.doPrivileged
1368	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1369	<	public Unsafe run() throws Exception {
1370	<	return getUnsafePrivileged();
1368	>	(new java.security
1369	>	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1370	>	public sun.misc.Unsafe run() throws Exception {
1371	>	java.lang.reflect.Field f = sun.misc
1372	>	.Unsafe.class.getDeclaredField("theUnsafe");
1373	>	f.setAccessible(true);
1374	>	return (sun.misc.Unsafe) f.get(null);
1375		}});
1376		} catch (java.security.PrivilegedActionException e) {
1377	<	throw e.getCause();
1377	>	throw new RuntimeException("Could not initialize intrinsics",
1378	>	e.getCause());
1379		}
1380		}
1381		}
1026	–
1027	–	private static Unsafe getUnsafePrivileged()
1028	–	throws NoSuchFieldException, IllegalAccessException {
1029	–	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1030	–	f.setAccessible(true);
1031	–	return (Unsafe) f.get(null);
1032	–	}
1033	–
1034	–	private static long fieldOffset(String fieldName)
1035	–	throws NoSuchFieldException {
1036	–	return _unsafe.objectFieldOffset
1037	–	(ForkJoinTask.class.getDeclaredField(fieldName));
1038	–	}
1039	–
1040	–	static final Unsafe _unsafe;
1041	–	static final long statusOffset;
1042	–
1043	–	static {
1044	–	try {
1045	–	_unsafe = getUnsafe();
1046	–	statusOffset = fieldOffset("status");
1047	–	} catch (Throwable e) {
1048	–	throw new RuntimeException("Could not initialize intrinsics", e);
1049	–	}
1050	–	}
1051	–
1382		}

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