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root/jsr166/jsr166/src/jsr166y/ForkJoinTask.java

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.1 by dl, Tue Jan 6 14:30:31 2009 UTC vs.
Revision 1.27 by dl, Sun Aug 2 11:54:31 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import java.io.Serializable;
9	<	import java.util.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.atomic.*;
11	<	import sun.misc.Unsafe;
12	<	import java.lang.reflect.*;
10	>
11	>	import java.io.Serializable;
12	>	import java.util.Collection;
13	>	import java.util.Collections;
14	>	import java.util.List;
15	>	import java.util.Map;
16	>	import java.util.WeakHashMap;
17
18		/**
19	<	* Abstract base class for tasks that run within a ForkJoinPool.  A
20	<	* ForkJoinTask is a thread-like entity that is much lighter weight
21	<	* than a normal thread.  Huge numbers of tasks and subtasks may be
22	<	* hosted by a small number of actual threads in a ForkJoinPool,
23	<	* at the price of some usage limitations.
19	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
20	>	* A {@code ForkJoinTask} is a thread-like entity that is much
21	>	* lighter weight than a normal thread.  Huge numbers of tasks and
22	>	* subtasks may be hosted by a small number of actual threads in a
23	>	* ForkJoinPool, at the price of some usage limitations.
24		*
25	<	* <p> ForkJoinTasks are forms of <tt>Futures</tt> supporting a
26	<	* limited range of use.  The "lightness" of ForkJoinTasks is due to a
27	<	* set of restrictions (that are only partially statically
28	<	* enforceable) reflecting their intended use as computational tasks
29	<	* calculating pure functions or operating on purely isolated objects.
30	<	* The primary coordination mechanisms supported for ForkJoinTasks are
31	<	* <tt>fork</tt>, that arranges asynchronous execution, and
32	<	* <tt>join</tt>, that doesn't proceed until the task's result has
33	<	* been computed. (Cancellation is also supported).  The computation
34	<	* defined in the <tt>compute</tt> method should avoid
35	<	* <tt>synchronized</tt> methods or blocks, and should minimize
36	<	* blocking synchronization apart from joining other tasks or using
25	>	* <p> A "main" ForkJoinTask begins execution when submitted to a
26	>	* {@link ForkJoinPool}. Once started, it will usually in turn start
27	>	* other subtasks.  As indicated by the name of this class, many
28	>	* programs using ForkJoinTasks employ only methods {@code fork} and
29	>	* {@code join}, or derivatives such as {@code invokeAll}.  However,
30	>	* this class also provides a number of other methods that can come
31	>	* into play in advanced usages, as well as extension mechanics that
32	>	* allow support of new forms of fork/join processing.
33	>	*
34	>	* <p>A ForkJoinTask is a lightweight form of {@link Future}.  The
35	>	* efficiency of ForkJoinTasks stems from a set of restrictions (that
36	>	* are only partially statically enforceable) reflecting their
37	>	* intended use as computational tasks calculating pure functions or
38	>	* operating on purely isolated objects.  The primary coordination
39	>	* mechanisms are {@link #fork}, that arranges asynchronous execution,
40	>	* and {@link #join}, that doesn't proceed until the task's result has
41	>	* been computed.  Computations should avoid {@code synchronized}
42	>	* methods or blocks, and should minimize other blocking
43	>	* synchronization apart from joining other tasks or using
44		* synchronizers such as Phasers that are advertised to cooperate with
45		* fork/join scheduling. Tasks should also not perform blocking IO,
46		* and should ideally access variables that are completely independent
#	Line 38 | Line 48 | import java.lang.reflect.*;
48		* restrictions, for example using shared output streams, may be
49		* tolerable in practice, but frequent use may result in poor
50		* performance, and the potential to indefinitely stall if the number
51	<	* of threads not waiting for external synchronization becomes
52	<	* exhausted. This usage restriction is in part enforced by not
53	<	* permitting checked exceptions such as IOExceptions to be
54	<	* thrown. However, computations may still encounter unchecked
51	>	* of threads not waiting for IO or other external synchronization
52	>	* becomes exhausted. This usage restriction is in part enforced by
53	>	* not permitting checked exceptions such as {@code IOExceptions}
54	>	* to be thrown. However, computations may still encounter unchecked
55		* exceptions, that are rethrown to callers attempting join
56		* them. These exceptions may additionally include
57		* RejectedExecutionExceptions stemming from internal resource
58		* exhaustion such as failure to allocate internal task queues.
59		*
60	<	* <p> The <tt>ForkJoinTask</tt> class is not usually directly
61	<	* subclassed.  Instead, you subclass one of the abstract classes that
62	<	* support different styles of fork/join processing.  Normally, a
63	<	* concrete ForkJoinTask subclass declares fields comprising its
64	<	* parameters, established in a constructor, and then defines a
65	<	* <tt>compute</tt> method that somehow uses the control methods
66	<	* supplied by this base class. While these methods have
67	<	* <tt>public</tt> access, some of them may only be called from within
68	<	* other ForkJoinTasks. Attempts to invoke them in other contexts
69	<	* result in exceptions or errors including ClassCastException.  The
70	<	* only way to invoke a "main" driver task is to submit it to a
71	<	* ForkJoinPool. Once started, this will usually in turn start other
72	<	* subtasks.
60	>	* <p>The primary method for awaiting completion and extracting
61	>	* results of a task is {@link #join}, but there are several variants:
62	>	* The {@link Future#get} methods support interruptible and/or timed
63	>	* waits for completion and report results using {@code Future}
64	>	* conventions. Method {@link #helpJoin} enables callers to actively
65	>	* execute other tasks while awaiting joins, which is sometimes more
66	>	* efficient but only applies when all subtasks are known to be
67	>	* strictly tree-structured. Method {@link #invoke} is semantically
68	>	* equivalent to {@code fork(); join()} but always attempts to
69	>	* begin execution in the current thread. The "<em>quiet</em>" forms
70	>	* of these methods do not extract results or report exceptions. These
71	>	* may be useful when a set of tasks are being executed, and you need
72	>	* to delay processing of results or exceptions until all complete.
73	>	* Method {@code invokeAll} (available in multiple versions)
74	>	* performs the most common form of parallel invocation: forking a set
75	>	* of tasks and joining them all.
76	>	*
77	>	* <p> The ForkJoinTask class is not usually directly subclassed.
78	>	* Instead, you subclass one of the abstract classes that support a
79	>	* particular style of fork/join processing, typically {@link
80	>	* RecursiveAction} for computations that do not return results, or
81	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
82	>	* ForkJoinTask subclass declares fields comprising its parameters,
83	>	* established in a constructor, and then defines a {@code compute}
84	>	* method that somehow uses the control methods supplied by this base
85	>	* class. While these methods have {@code public} access (to allow
86	>	* instances of different task subclasses to call each others
87	>	* methods), some of them may only be called from within other
88	>	* ForkJoinTasks (as may be determined using method {@link
89	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
90	>	* result in exceptions or errors, possibly including
91	>	* ClassCastException.
92		*
93	<	* <p>Most base support methods are <tt>final</tt> because their
93	>	* <p>Most base support methods are {@code final} because their
94		* implementations are intrinsically tied to the underlying
95		* lightweight task scheduling framework, and so cannot be overridden.
96		* Developers creating new basic styles of fork/join processing should
97	<	* minimally implement protected methods <tt>exec</tt>,
98	<	* <tt>setRawResult</tt>, and <tt>getRawResult</tt>, while also
99	<	* introducing an abstract computational method that can be
100	<	* implemented in its subclasses. To support such extensions,
101	<	* instances of ForkJoinTasks maintain an atomically updated
102	<	* <tt>short</tt> representing user-defined control state.  Control
74	<	* state is guaranteed initially to be zero, and to be negative upon
75	<	* completion, but may otherwise be used for any other control
76	<	* purposes, such as maintaining join counts.  The {@link
77	<	* ForkJoinWorkerThread} class supports additional inspection and
78	<	* tuning methods that can be useful when developing extensions.
97	>	* minimally implement {@code protected} methods
98	>	* {@link #exec}, {@link #setRawResult}, and
99	>	* {@link #getRawResult}, while also introducing an abstract
100	>	* computational method that can be implemented in its subclasses,
101	>	* possibly relying on other {@code protected} methods provided
102	>	* by this class.
103		*
104		* <p>ForkJoinTasks should perform relatively small amounts of
105	<	* computations, othewise splitting into smaller tasks. As a very
105	>	* computations, otherwise splitting into smaller tasks. As a very
106		* rough rule of thumb, a task should perform more than 100 and less
107		* than 10000 basic computational steps. If tasks are too big, then
108	<	* parellelism cannot improve throughput. If too small, then memory
108	>	* parallelism cannot improve throughput. If too small, then memory
109		* and internal task maintenance overhead may overwhelm processing.
110		*
111	<	* <p>ForkJoinTasks are <tt>Serializable</tt>, which enables them to
112	<	* be used in extensions such as remote execution frameworks. However,
113	<	* it is in general safe to serialize tasks only before or after, but
111	>	* <p>This class provides {@code adapt} methods for {@link
112	>	* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that
113	>	* may be of use when mixing execution of ForkJoinTasks with other
114	>	* kinds of tasks. When all tasks are of this form, consider using a
115	>	* pool in {@link ForkJoinPool#setAsyncMode}.
116	>	*
117	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them
118	>	* to be used in extensions such as remote execution frameworks. It is
119	>	* in general sensible to serialize tasks only before or after, but
120		* not during execution. Serialization is not relied on during
121		* execution itself.
122	+	*
123	+	* @since 1.7
124	+	* @author Doug Lea
125		*/
126		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
127	+
128		/**
129	<	* Status field holding all run status. We pack this into a single
130	<	* int both to minimize footprint overhead and to ensure atomicity
131	<	* (updates are via CAS).
98	<	*
99	<	* Status is initially zero, and takes on nonnegative values until
129	>	* Run control status bits packed into a single int to minimize
130	>	* footprint and to ensure atomicity (via CAS).  Status is
131	>	* initially zero, and takes on nonnegative values until
132		* completed, upon which status holds COMPLETED. CANCELLED, or
133		* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
134		* blocking waits by other threads have SIGNAL_MASK bits set --
#	Line 111 | Line 143 | public abstract class ForkJoinTask<V> im
143		* currently unused. Also value 0x80000000 is available as spare
144		* completion value.
145		*/
146	<	volatile int status; // accessed directy by pool and workers
146	>	volatile int status; // accessed directly by pool and workers
147
148		static final int COMPLETION_MASK      = 0xe0000000;
149		static final int NORMAL               = 0xe0000000; // == mask
#	Line 124 | Line 156 | public abstract class ForkJoinTask<V> im
156		/**
157		* Table of exceptions thrown by tasks, to enable reporting by
158		* callers. Because exceptions are rare, we don't directly keep
159	<	* them with task objects, but instead us a weak ref table.  Note
159	>	* them with task objects, but instead use a weak ref table.  Note
160		* that cancellation exceptions don't appear in the table, but are
161		* instead recorded as status values.
162	<	* Todo: Use ConcurrentReferenceHashMap
162	>	* TODO: Use ConcurrentReferenceHashMap
163		*/
164		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
165		Collections.synchronizedMap
#	Line 136 | Line 168 | public abstract class ForkJoinTask<V> im
168		// within-package utilities
169
170		/**
171	<	* Get current worker thread, or null if not a worker thread
171	>	* Gets current worker thread, or null if not a worker thread.
172		*/
173		static ForkJoinWorkerThread getWorker() {
174		Thread t = Thread.currentThread();
175	<	return ((t instanceof ForkJoinWorkerThread)?
176	<	(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);
175	>	return ((t instanceof ForkJoinWorkerThread) ?
176	>	(ForkJoinWorkerThread) t : null);
177		}
178
179		final boolean casStatus(int cmp, int val) {
180	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
180	>	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
181		}
182
183		/**
#	Line 162 | Line 185 | public abstract class ForkJoinTask<V> im
185		*/
186		static void rethrowException(Throwable ex) {
187		if (ex != null)
188	<	_unsafe.throwException(ex);
188	>	UNSAFE.throwException(ex);
189		}
190
191		// Setting completion status
192
193		/**
194	<	* Mark completion and wake up threads waiting to join this task.
194	>	* Marks completion and wakes up threads waiting to join this task.
195	>	*
196		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
197		*/
198		final void setCompletion(int completion) {
199	<	ForkJoinPool pool = getWorkerPool();
199	>	ForkJoinPool pool = getPool();
200		if (pool != null) {
201		int s; // Clear signal bits while setting completion status
202	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
202	>	do {} while ((s = status) >= 0 && !casStatus(s, completion));
203
204		if ((s & SIGNAL_MASK) != 0) {
205		if ((s &= INTERNAL_SIGNAL_MASK) != 0)
206		pool.updateRunningCount(s);
207	<	synchronized(this) { notifyAll(); }
207	>	synchronized (this) { notifyAll(); }
208		}
209		}
210		else
#	Line 193 | Line 217 | public abstract class ForkJoinTask<V> im
217		*/
218		private void externallySetCompletion(int completion) {
219		int s;
220	<	do;while ((s = status) >= 0 &&
221	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
222	<	synchronized(this) { notifyAll(); }
220	>	do {} while ((s = status) >= 0 &&
221	>	!casStatus(s, (s & SIGNAL_MASK) | completion));
222	>	synchronized (this) { notifyAll(); }
223		}
224
225		/**
226	<	* Sets status to indicate normal completion
226	>	* Sets status to indicate normal completion.
227		*/
228		final void setNormalCompletion() {
229		// Try typical fast case -- single CAS, no signal, not already done.
230		// Manually expand casStatus to improve chances of inlining it
231	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
231	>	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
232		setCompletion(NORMAL);
233		}
234
235		// internal waiting and notification
236
237		/**
238	<	* Performs the actual monitor wait for awaitDone
238	>	* Performs the actual monitor wait for awaitDone.
239		*/
240		private void doAwaitDone() {
241		// Minimize lock bias and in/de-flation effects by maximizing
242		// chances of waiting inside sync
243		try {
244		while (status >= 0)
245	<	synchronized(this) { if (status >= 0) wait(); }
245	>	synchronized (this) { if (status >= 0) wait(); }
246		} catch (InterruptedException ie) {
247		onInterruptedWait();
248		}
249		}
250
251		/**
252	<	* Performs the actual monitor wait for awaitDone
252	>	* Performs the actual timed monitor wait for awaitDone.
253		*/
254		private void doAwaitDone(long startTime, long nanos) {
255	<	synchronized(this) {
255	>	synchronized (this) {
256		try {
257		while (status >= 0) {
258	<	long nt = nanos - System.nanoTime() - startTime;
258	>	long nt = nanos - (System.nanoTime() - startTime);
259		if (nt <= 0)
260		break;
261	<	wait(nt / 1000000, (int)(nt % 1000000));
261	>	wait(nt / 1000000, (int) (nt % 1000000));
262		}
263		} catch (InterruptedException ie) {
264		onInterruptedWait();
#	Line 247 | Line 271 | public abstract class ForkJoinTask<V> im
271		/**
272		* Sets status to indicate there is joiner, then waits for join,
273		* surrounded with pool notifications.
274	+	*
275		* @return status upon exit
276		*/
277	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
278	<	ForkJoinPool pool = w == null? null : w.pool;
277	>	private int awaitDone(ForkJoinWorkerThread w,
278	>	boolean maintainParallelism) {
279	>	ForkJoinPool pool = (w == null) ? null : w.pool;
280		int s;
281		while ((s = status) >= 0) {
282	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
282	>	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
283		if (pool == null || !pool.preJoin(this, maintainParallelism))
284		doAwaitDone();
285		if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
#	Line 266 | Line 292 | public abstract class ForkJoinTask<V> im
292
293		/**
294		* Timed version of awaitDone
295	+	*
296		* @return status upon exit
297		*/
298	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
299	<	ForkJoinPool pool = w == null? null : w.pool;
298	>	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
299	>	ForkJoinPool pool = (w == null) ? null : w.pool;
300		int s;
301		while ((s = status) >= 0) {
302	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
302	>	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
303		long startTime = System.nanoTime();
304		if (pool == null || !pool.preJoin(this, false))
305		doAwaitDone(startTime, nanos);
#	Line 289 | Line 316 | public abstract class ForkJoinTask<V> im
316		}
317
318		/**
319	<	* Notify pool that thread is unblocked. Called by signalled
319	>	* Notifies pool that thread is unblocked. Called by signalled
320		* threads when woken by non-FJ threads (which is atypical).
321		*/
322		private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
323		int s;
324	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
324	>	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
325		if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
326		pool.updateRunningCount(s);
327		}
328
329		/**
330	<	* Notify pool to adjust counts on cancelled or timed out wait
330	>	* Notifies pool to adjust counts on cancelled or timed out wait.
331		*/
332		private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
333		if (pool != null) {
#	Line 314 | Line 341 | public abstract class ForkJoinTask<V> im
341		}
342		}
343
344	+	/**
345	+	* Handles interruptions during waits.
346	+	*/
347		private void onInterruptedWait() {
348	<	Thread t = Thread.currentThread();
349	<	if (t instanceof ForkJoinWorkerThread) {
350	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)t;
351	<	if (w.isTerminating())
352	<	cancelIgnoreExceptions();
353	<	}
324	<	else { // re-interrupt
325	<	try {
326	<	t.interrupt();
327	<	} catch (SecurityException ignore) {
328	<	}
329	<	}
348	>	ForkJoinWorkerThread w = getWorker();
349	>	if (w == null)
350	>	Thread.currentThread().interrupt(); // re-interrupt
351	>	else if (w.isTerminating())
352	>	cancelIgnoringExceptions();
353	>	// else if FJworker, ignore interrupt
354		}
355
356		// Recording and reporting exceptions
#	Line 337 | Line 361 | public abstract class ForkJoinTask<V> im
361		}
362
363		/**
364	<	* Throws the exception associated with status s;
364	>	* Throws the exception associated with status s.
365	>	*
366		* @throws the exception
367		*/
368		private void reportException(int s) {
#	Line 350 | Line 375 | public abstract class ForkJoinTask<V> im
375		}
376
377		/**
378	<	* Returns result or throws exception using j.u.c.Future conventions
379	<	* Only call when isDone known to be true.
378	>	* Returns result or throws exception using j.u.c.Future conventions.
379	>	* Only call when {@code isDone} known to be true.
380		*/
381		private V reportFutureResult()
382		throws ExecutionException, InterruptedException {
#	Line 370 | Line 395 | public abstract class ForkJoinTask<V> im
395
396		/**
397		* Returns result or throws exception using j.u.c.Future conventions
398	<	* with timeouts
398	>	* with timeouts.
399		*/
400		private V reportTimedFutureResult()
401		throws InterruptedException, ExecutionException, TimeoutException {
#	Line 391 | Line 416 | public abstract class ForkJoinTask<V> im
416
417		/**
418		* Calls exec, recording completion, and rethrowing exception if
419	<	* encountered. Caller should normally check status before calling
419	>	* encountered. Caller should normally check status before calling.
420	>	*
421		* @return true if completed normally
422		*/
423		private boolean tryExec() {
#	Line 409 | Line 435 | public abstract class ForkJoinTask<V> im
435
436		/**
437		* Main execution method used by worker threads. Invokes
438	<	* base computation unless already complete
438	>	* base computation unless already complete.
439		*/
440		final void quietlyExec() {
441		if (status >= 0) {
442		try {
443		if (!exec())
444		return;
445	<	} catch(Throwable rex) {
445	>	} catch (Throwable rex) {
446		setDoneExceptionally(rex);
447		return;
448		}
#	Line 425 | Line 451 | public abstract class ForkJoinTask<V> im
451		}
452
453		/**
454	<	* Calls exec, recording but not rethrowing exception
455	<	* Caller should normally check status before calling
454	>	* Calls exec(), recording but not rethrowing exception.
455	>	* Caller should normally check status before calling.
456	>	*
457		* @return true if completed normally
458		*/
459		private boolean tryQuietlyInvoke() {
#	Line 442 | Line 469 | public abstract class ForkJoinTask<V> im
469		}
470
471		/**
472	<	* Cancel, ignoring any exceptions it throws
472	>	* Cancels, ignoring any exceptions it throws.
473		*/
474	<	final void cancelIgnoreExceptions() {
474	>	final void cancelIgnoringExceptions() {
475		try {
476		cancel(false);
477	<	} catch(Throwable ignore) {
477	>	} catch (Throwable ignore) {
478		}
479		}
480
481	+	/**
482	+	* Main implementation of helpJoin
483	+	*/
484	+	private int busyJoin(ForkJoinWorkerThread w) {
485	+	int s;
486	+	ForkJoinTask<?> t;
487	+	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
488	+	t.quietlyExec();
489	+	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
490	+	}
491	+
492		// public methods
493
494		/**
495		* Arranges to asynchronously execute this task.  While it is not
496		* necessarily enforced, it is a usage error to fork a task more
497		* than once unless it has completed and been reinitialized.  This
498	<	* method may be invoked only from within other ForkJoinTask
499	<	* computations. Attempts to invoke in other contexts result in
500	<	* exceptions or errors including ClassCastException.
498	>	* method may be invoked only from within ForkJoinTask
499	>	* computations (as may be determined using method {@link
500	>	* #inForkJoinPool}). Attempts to invoke in other contexts result
501	>	* in exceptions or errors, possibly including ClassCastException.
502	>	*
503	>	* @return {@code this}, to simplify usage.
504		*/
505	<	public final void fork() {
506	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
505	>	public final ForkJoinTask<V> fork() {
506	>	((ForkJoinWorkerThread) Thread.currentThread())
507	>	.pushTask(this);
508	>	return this;
509		}
510
511		/**
512		* Returns the result of the computation when it is ready.
513	<	* This method differs from <tt>get</tt> in that abnormal
513	>	* This method differs from {@code get} in that abnormal
514		* completion results in RuntimeExceptions or Errors, not
515		* ExecutionExceptions.
516		*
#	Line 480 | Line 523 | public abstract class ForkJoinTask<V> im
523		return getRawResult();
524		}
525
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();
496	–	}
497	–
498	–	/**
499	–	* Possibly executes other tasks until this task is ready, then
500	–	* returns the result of the computation.  This method may be more
501	–	* efficient than <tt>join</tt>, but is only applicable when there
502	–	* are no potemtial dependencies between continuation of the
503	–	* current task and that of any other task that might be executed
504	–	* while helping. (This usually holds for pure divide-and-conquer
505	–	* tasks).
506	–	* @return the computed result
507	–	*/
508	–	public final V helpJoin() {
509	–	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
510	–	if (status < 0 || !w.unpushTask(this) || !tryExec())
511	–	reportException(w.helpJoinTask(this));
512	–	return getRawResult();
513	–	}
514	–
526		/**
527	<	* Performs this task, awaits its completion if necessary, and
528	<	* return its result.
527	>	* Commences performing this task, awaits its completion if
528	>	* necessary, and return its result.
529	>	*
530		* @throws Throwable (a RuntimeException, Error, or unchecked
531	<	* exception) if the underlying computation did so.
531	>	* exception) if the underlying computation did so
532		* @return the computed result
533		*/
534		public final V invoke() {
#	Line 527 | Line 539 | public abstract class ForkJoinTask<V> im
539		}
540
541		/**
542	<	* Joins this task, without returning its result or throwing an
543	<	* exception. This method may be useful when processing
544	<	* collections of tasks when some have been cancelled or otherwise
545	<	* known to have aborted.
542	>	* Forks the given tasks, returning when {@code isDone} holds for
543	>	* each task or an exception is encountered. This method may be
544	>	* invoked only from within ForkJoinTask computations (as may be
545	>	* determined using method {@link #inForkJoinPool}). Attempts to
546	>	* invoke in other contexts result in exceptions or errors,
547	>	* possibly including ClassCastException.
548	>	*
549	>	* @param t1 the first task
550	>	* @param t2 the second task
551	>	* @throws NullPointerException if any task is null
552	>	* @throws RuntimeException or Error if a task did so
553		*/
554	<	public final void quietlyJoin() {
555	<	if (status >= 0) {
556	<	ForkJoinWorkerThread w = getWorker();
557	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
539	<	awaitDone(w, true);
540	<	}
554	>	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
555	>	t2.fork();
556	>	t1.invoke();
557	>	t2.join();
558		}
559
560		/**
561	<	* Possibly executes other tasks until this task is ready.
561	>	* Forks the given tasks, returning when {@code isDone} holds for
562	>	* each task or an exception is encountered. If any task
563	>	* encounters an exception, others may be, but are not guaranteed
564	>	* to be, cancelled.  This method may be invoked only from within
565	>	* ForkJoinTask computations (as may be determined using method
566	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
567	>	* result in exceptions or errors, possibly including
568	>	* ClassCastException.
569	>	*
570	>	* Overloadings of this method exist for the special cases
571	>	* of one to four arguments.
572	>	*
573	>	* @param tasks the tasks
574	>	* @throws NullPointerException if tasks or any element are null
575	>	* @throws RuntimeException or Error if any task did so
576		*/
577	<	public final void quietlyHelpJoin() {
578	<	if (status >= 0) {
579	<	ForkJoinWorkerThread w =
580	<	(ForkJoinWorkerThread)(Thread.currentThread());
581	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
582	<	w.helpJoinTask(this);
577	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
578	>	Throwable ex = null;
579	>	int last = tasks.length - 1;
580	>	for (int i = last; i >= 0; --i) {
581	>	ForkJoinTask<?> t = tasks[i];
582	>	if (t == null) {
583	>	if (ex == null)
584	>	ex = new NullPointerException();
585	>	}
586	>	else if (i != 0)
587	>	t.fork();
588	>	else {
589	>	t.quietlyInvoke();
590	>	if (ex == null)
591	>	ex = t.getException();
592	>	}
593	>	}
594	>	for (int i = 1; i <= last; ++i) {
595	>	ForkJoinTask<?> t = tasks[i];
596	>	if (t != null) {
597	>	if (ex != null)
598	>	t.cancel(false);
599	>	else {
600	>	t.quietlyJoin();
601	>	if (ex == null)
602	>	ex = t.getException();
603	>	}
604	>	}
605		}
606	+	if (ex != null)
607	+	rethrowException(ex);
608		}
609
610		/**
611	<	* Performs this task and awaits its completion if necessary,
612	<	* without returning its result or throwing an exception. This
613	<	* method may be useful when processing collections of tasks when
614	<	* some have been cancelled or otherwise known to have aborted.
615	<	*/
616	<	public final void quietlyInvoke() {
617	<	if (status >= 0 && !tryQuietlyInvoke())
618	<	quietlyJoin();
611	>	* Forks all tasks in the collection, returning when {@code
612	>	* isDone} holds for each task or an exception is encountered. If
613	>	* any task encounters an exception, others may be, but are not
614	>	* guaranteed to be, cancelled.  This method may be invoked only
615	>	* from within ForkJoinTask computations (as may be determined
616	>	* using method {@link #inForkJoinPool}). Attempts to invoke in
617	>	* other contexts result in exceptions or errors, possibly
618	>	* including ClassCastException.
619	>	*
620	>	* @param tasks the collection of tasks
621	>	* @return the tasks argument, to simplify usage
622	>	* @throws NullPointerException if tasks or any element are null
623	>	* @throws RuntimeException or Error if any task did so
624	>	*/
625	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
626	>	if (!(tasks instanceof List<?>)) {
627	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
628	>	return tasks;
629	>	}
630	>	@SuppressWarnings("unchecked")
631	>	List<? extends ForkJoinTask<?>> ts =
632	>	(List<? extends ForkJoinTask<?>>) tasks;
633	>	Throwable ex = null;
634	>	int last = ts.size() - 1;
635	>	for (int i = last; i >= 0; --i) {
636	>	ForkJoinTask<?> t = ts.get(i);
637	>	if (t == null) {
638	>	if (ex == null)
639	>	ex = new NullPointerException();
640	>	}
641	>	else if (i != 0)
642	>	t.fork();
643	>	else {
644	>	t.quietlyInvoke();
645	>	if (ex == null)
646	>	ex = t.getException();
647	>	}
648	>	}
649	>	for (int i = 1; i <= last; ++i) {
650	>	ForkJoinTask<?> t = ts.get(i);
651	>	if (t != null) {
652	>	if (ex != null)
653	>	t.cancel(false);
654	>	else {
655	>	t.quietlyJoin();
656	>	if (ex == null)
657	>	ex = t.getException();
658	>	}
659	>	}
660	>	}
661	>	if (ex != null)
662	>	rethrowException(ex);
663	>	return tasks;
664		}
665
666		/**
667	<	* Returns true if the computation performed by this task has
668	<	* completed (or has been cancelled).
669	<	* @return true if this computation has completed
667	>	* Returns {@code true} if the computation performed by this task
668	>	* has completed (or has been cancelled).
669	>	*
670	>	* @return {@code true} if this computation has completed
671		*/
672		public final boolean isDone() {
673		return status < 0;
674		}
675
676		/**
677	<	* Returns true if this task was cancelled.
678	<	* @return true if this task was cancelled
677	>	* Returns {@code true} if this task was cancelled.
678	>	*
679	>	* @return {@code true} if this task was cancelled
680		*/
681		public final boolean isCancelled() {
682		return (status & COMPLETION_MASK) == CANCELLED;
683		}
684
685		/**
584	–	* Returns true if this task threw an exception or was cancelled
585	–	* @return true if this task threw an exception or was cancelled
586	–	*/
587	–	public final boolean completedAbnormally() {
588	–	return (status & COMPLETION_MASK) < NORMAL;
589	–	}
590	–
591	–	/**
592	–	* Returns the exception thrown by the base computation, or a
593	–	* CancellationException if cancelled, or null if none or if the
594	–	* method has not yet completed.
595	–	* @return the exception, or null if none
596	–	*/
597	–	public final Throwable getException() {
598	–	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);
604	–	}
605	–
606	–	/**
686		* Asserts that the results of this task's computation will not be
687	<	* used. If a cancellation occurs before this task is processed,
688	<	* then its <tt>compute</tt> method will not be executed,
689	<	* <tt>isCancelled</tt> will report true, and <tt>join</tt> will
690	<	* result in a CancellationException being thrown. Otherwise, when
687	>	* used. If a cancellation occurs before attempting to execute this
688	>	* task, execution will be suppressed, {@link #isCancelled}
689	>	* will report true, and {@link #join} will result in a
690	>	* {@code CancellationException} being thrown. Otherwise, when
691		* cancellation races with completion, there are no guarantees
692	<	* about whether <tt>isCancelled</tt> will report true, whether
693	<	* <tt>join</tt> will return normally or via an exception, or
694	<	* whether these behaviors will remain consistent upon repeated
692	>	* about whether {@code isCancelled} will report {@code true},
693	>	* whether {@code join} will return normally or via an exception,
694	>	* or whether these behaviors will remain consistent upon repeated
695		* invocation.
696		*
697		* <p>This method may be overridden in subclasses, but if so, must
#	Line 622 | Line 701 | public abstract class ForkJoinTask<V> im
701		* <p> This method is designed to be invoked by <em>other</em>
702		* tasks. To terminate the current task, you can just return or
703		* throw an unchecked exception from its computation method, or
704	<	* invoke <tt>completeExceptionally(someException)</tt>.
704	>	* invoke {@link #completeExceptionally}.
705		*
706		* @param mayInterruptIfRunning this value is ignored in the
707		* default implementation because tasks are not in general
708	<	* cancelled via interruption.
708	>	* cancelled via interruption
709		*
710	<	* @return true if this task is now cancelled
710	>	* @return {@code true} if this task is now cancelled
711		*/
712		public boolean cancel(boolean mayInterruptIfRunning) {
713		setCompletion(CANCELLED);
#	Line 636 | Line 715 | public abstract class ForkJoinTask<V> im
715		}
716
717		/**
718	+	* Returns {@code true} if this task threw an exception or was cancelled.
719	+	*
720	+	* @return {@code true} if this task threw an exception or was cancelled
721	+	*/
722	+	public final boolean isCompletedAbnormally() {
723	+	return (status & COMPLETION_MASK) < NORMAL;
724	+	}
725	+
726	+	/**
727	+	* Returns the exception thrown by the base computation, or a
728	+	* CancellationException if cancelled, or null if none or if the
729	+	* method has not yet completed.
730	+	*
731	+	* @return the exception, or {@code null} if none
732	+	*/
733	+	public final Throwable getException() {
734	+	int s = status & COMPLETION_MASK;
735	+	if (s >= NORMAL)
736	+	return null;
737	+	if (s == CANCELLED)
738	+	return new CancellationException();
739	+	return exceptionMap.get(this);
740	+	}
741	+
742	+	/**
743		* Completes this task abnormally, and if not already aborted or
744		* cancelled, causes it to throw the given exception upon
745	<	* <tt>join</tt> and related operations. This method may be used
745	>	* {@code join} and related operations. This method may be used
746		* to induce exceptions in asynchronous tasks, or to force
747	<	* completion of tasks that would not otherwise complete.  This
748	<	* method is overridable, but overridden versions must invoke
749	<	* <tt>super</tt> implementation to maintain guarantees.
747	>	* completion of tasks that would not otherwise complete.  Its use
748	>	* in other situations is discouraged.  This method is
749	>	* overridable, but overridden versions must invoke {@code super}
750	>	* implementation to maintain guarantees.
751	>	*
752		* @param ex the exception to throw. If this exception is
753		* not a RuntimeException or Error, the actual exception thrown
754		* will be a RuntimeException with cause ex.
755		*/
756		public void completeExceptionally(Throwable ex) {
757		setDoneExceptionally((ex instanceof RuntimeException) ||
758	<	(ex instanceof Error)? ex :
758	>	(ex instanceof Error) ? ex :
759		new RuntimeException(ex));
760		}
761
762		/**
763		* Completes this task, and if not already aborted or cancelled,
764	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
764	>	* returning a {@code null} result upon {@code join} and related
765		* operations. This method may be used to provide results for
766		* asynchronous tasks, or to provide alternative handling for
767	<	* tasks that would not otherwise complete normally.
767	>	* tasks that would not otherwise complete normally. Its use in
768	>	* other situations is discouraged. This method is
769	>	* overridable, but overridden versions must invoke {@code super}
770	>	* implementation to maintain guarantees.
771		*
772	<	* @param value the result value for this task.
772	>	* @param value the result value for this task
773		*/
774		public void complete(V value) {
775		try {
776		setRawResult(value);
777	<	} catch(Throwable rex) {
777	>	} catch (Throwable rex) {
778		setDoneExceptionally(rex);
779		return;
780		}
781		setNormalCompletion();
782		}
783
784	+	public final V get() throws InterruptedException, ExecutionException {
785	+	ForkJoinWorkerThread w = getWorker();
786	+	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
787	+	awaitDone(w, true);
788	+	return reportFutureResult();
789	+	}
790	+
791	+	public final V get(long timeout, TimeUnit unit)
792	+	throws InterruptedException, ExecutionException, TimeoutException {
793	+	long nanos = unit.toNanos(timeout);
794	+	ForkJoinWorkerThread w = getWorker();
795	+	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
796	+	awaitDone(w, nanos);
797	+	return reportTimedFutureResult();
798	+	}
799	+
800	+	/**
801	+	* Possibly executes other tasks until this task is ready, then
802	+	* returns the result of the computation.  This method may be more
803	+	* efficient than {@code join}, but is only applicable when
804	+	* there are no potential dependencies between continuation of the
805	+	* current task and that of any other task that might be executed
806	+	* while helping. (This usually holds for pure divide-and-conquer
807	+	* tasks). This method may be invoked only from within
808	+	* ForkJoinTask computations (as may be determined using method
809	+	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
810	+	* result in exceptions or errors, possibly including
811	+	* ClassCastException.
812	+	*
813	+	* @return the computed result
814	+	*/
815	+	public final V helpJoin() {
816	+	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
817	+	if (status < 0 || !w.unpushTask(this) || !tryExec())
818	+	reportException(busyJoin(w));
819	+	return getRawResult();
820	+	}
821	+
822	+	/**
823	+	* Possibly executes other tasks until this task is ready.  This
824	+	* method may be invoked only from within ForkJoinTask
825	+	* computations (as may be determined using method {@link
826	+	* #inForkJoinPool}). Attempts to invoke in other contexts result
827	+	* in exceptions or errors, possibly including ClassCastException.
828	+	*/
829	+	public final void quietlyHelpJoin() {
830	+	if (status >= 0) {
831	+	ForkJoinWorkerThread w =
832	+	(ForkJoinWorkerThread) Thread.currentThread();
833	+	if (!w.unpushTask(this) || !tryQuietlyInvoke())
834	+	busyJoin(w);
835	+	}
836	+	}
837	+
838	+	/**
839	+	* Joins this task, without returning its result or throwing an
840	+	* exception. This method may be useful when processing
841	+	* collections of tasks when some have been cancelled or otherwise
842	+	* known to have aborted.
843	+	*/
844	+	public final void quietlyJoin() {
845	+	if (status >= 0) {
846	+	ForkJoinWorkerThread w = getWorker();
847	+	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
848	+	awaitDone(w, true);
849	+	}
850	+	}
851	+
852	+	/**
853	+	* Commences performing this task and awaits its completion if
854	+	* necessary, without returning its result or throwing an
855	+	* exception. This method may be useful when processing
856	+	* collections of tasks when some have been cancelled or otherwise
857	+	* known to have aborted.
858	+	*/
859	+	public final void quietlyInvoke() {
860	+	if (status >= 0 && !tryQuietlyInvoke())
861	+	quietlyJoin();
862	+	}
863	+
864	+	/**
865	+	* Possibly executes tasks until the pool hosting the current task
866	+	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
867	+	* designs in which many tasks are forked, but none are explicitly
868	+	* joined, instead executing them until all are processed.  This
869	+	* method may be invoked only from within ForkJoinTask
870	+	* computations (as may be determined using method {@link
871	+	* #inForkJoinPool}). Attempts to invoke in other contexts result
872	+	* in exceptions or errors, possibly including ClassCastException.
873	+	*/
874	+	public static void helpQuiesce() {
875	+	((ForkJoinWorkerThread) Thread.currentThread())
876	+	.helpQuiescePool();
877	+	}
878	+
879		/**
880		* Resets the internal bookkeeping state of this task, allowing a
881	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
881	>	* subsequent {@code fork}. This method allows repeated reuse of
882		* this task, but only if reuse occurs when this task has either
883		* never been forked, or has been forked, then completed and all
884		* outstanding joins of this task have also completed. Effects
885		* under any other usage conditions are not guaranteed, and are
886	<	* almost surely wrong. This method may be useful when executing
886	>	* discouraged. This method may be useful when executing
887		* pre-constructed trees of subtasks in loops.
888		*/
889		public void reinitialize() {
#	Line 689 | Line 893 | public abstract class ForkJoinTask<V> im
893		}
894
895		/**
896	<	* Tries to unschedule this task for execution. This method will
897	<	* typically succeed if this task is the next task that would be
898	<	* executed by the current thread, and will typically fail (return
899	<	* false) otherwise. This method may be useful when arranging
900	<	* faster local processing of tasks that could have been, but were
697	<	* not, stolen.
698	<	* @return true if unforked
896	>	* Returns the pool hosting the current task execution, or null
897	>	* if this task is executing outside of any ForkJoinPool.
898	>	*
899	>	* @see #inForkJoinPool
900	>	* @return the pool, or {@code null} if none
901		*/
902	<	public boolean tryUnfork() {
903	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
902	>	public static ForkJoinPool getPool() {
903	>	Thread t = Thread.currentThread();
904	>	return (t instanceof ForkJoinWorkerThread) ?
905	>	((ForkJoinWorkerThread) t).pool : null;
906		}
907
908		/**
909	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
910	<	* of them or an exception is encountered. This method may be
911	<	* invoked only from within other ForkJoinTask
912	<	* computations. Attempts to invoke in other contexts result in
913	<	* exceptions or errors including ClassCastException.
710	<	* @param t1 one task
711	<	* @param t2 the other task
712	<	* @throws NullPointerException if t1 or t2 are null
713	<	* @throws RuntimeException or Error if either task did so.
909	>	* Returns {@code true} if the current thread is executing as a
910	>	* ForkJoinPool computation.
911	>	*
912	>	* @return {@code true} if the current thread is executing as a
913	>	* ForkJoinPool computation, or false otherwise
914		*/
915	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
916	<	t2.fork();
717	<	t1.invoke();
718	<	t2.join();
915	>	public static boolean inForkJoinPool() {
916	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
917		}
918
919		/**
920	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
921	<	* all of them. If any task encounters an exception, others may be
922	<	* cancelled.  This method may be invoked only from within other
923	<	* ForkJoinTask computations. Attempts to invoke in other contexts
924	<	* result in exceptions or errors including ClassCastException.
925	<	* @param tasks the array of tasks
926	<	* @throws NullPointerException if tasks or any element are null.
927	<	* @throws RuntimeException or Error if any task did so.
928	<	*/
929	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
930	<	Throwable ex = null;
931	<	int last = tasks.length - 1;
734	<	for (int i = last; i >= 0; --i) {
735	<	ForkJoinTask<?> t = tasks[i];
736	<	if (t == null) {
737	<	if (ex == null)
738	<	ex = new NullPointerException();
739	<	}
740	<	else if (i != 0)
741	<	t.fork();
742	<	else {
743	<	t.quietlyInvoke();
744	<	if (ex == null)
745	<	ex = t.getException();
746	<	}
747	<	}
748	<	for (int i = 1; i <= last; ++i) {
749	<	ForkJoinTask<?> t = tasks[i];
750	<	if (t != null) {
751	<	if (ex != null)
752	<	t.cancel(false);
753	<	else {
754	<	t.quietlyJoin();
755	<	if (ex == null)
756	<	ex = t.getException();
757	<	}
758	<	}
759	<	}
760	<	if (ex != null)
761	<	rethrowException(ex);
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.
920	>	* Tries to unschedule this task for execution. This method will
921	>	* typically succeed if this task is the most recently forked task
922	>	* by the current thread, and has not commenced executing in
923	>	* another thread.  This method may be useful when arranging
924	>	* alternative local processing of tasks that could have been, but
925	>	* were not, stolen. This method may be invoked only from within
926	>	* ForkJoinTask computations (as may be determined using method
927	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
928	>	* result in exceptions or errors, possibly including
929	>	* ClassCastException.
930	>	*
931	>	* @return {@code true} if unforked
932		*/
933	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
934	<	if (!(tasks instanceof List)) {
935	<	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);
933	>	public boolean tryUnfork() {
934	>	return ((ForkJoinWorkerThread) Thread.currentThread())
935	>	.unpushTask(this);
936		}
937
938		/**
939	<	* Possibly executes tasks until the pool hosting the current task
940	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
941	<	* designs in which many tasks are forked, but none are explicitly
942	<	* joined, instead executing them until all are processed.
939	>	* Returns an estimate of the number of tasks that have been
940	>	* forked by the current worker thread but not yet executed. This
941	>	* value may be useful for heuristic decisions about whether to
942	>	* fork other tasks.  This method may be invoked only from within
943	>	* ForkJoinTask computations (as may be determined using method
944	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
945	>	* result in exceptions or errors, possibly including
946	>	* ClassCastException.
947	>	* @return the number of tasks
948		*/
949	<	public static void helpQuiesce() {
950	<	((ForkJoinWorkerThread)(Thread.currentThread())).
951	<	helpQuiescePool();
949	>	public static int getQueuedTaskCount() {
950	>	return ((ForkJoinWorkerThread) Thread.currentThread())
951	>	.getQueueSize();
952		}
953
954		/**
955	<	* Returns a estimate of how many more locally queued tasks are
955	>	* Returns an estimate of how many more locally queued tasks are
956		* held by the current worker thread than there are other worker
957	<	* threads that might want to steal them.  This value may be
958	<	* useful for heuristic decisions about whether to fork other
959	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
960	<	* worker should aim to maintain a small constant surplus (for
961	<	* example, 3) of tasks, and to process computations locally if
962	<	* this threshold is exceeded.
957	>	* threads that might steal them.  This value may be useful for
958	>	* heuristic decisions about whether to fork other tasks. In many
959	>	* usages of ForkJoinTasks, at steady state, each worker should
960	>	* aim to maintain a small constant surplus (for example, 3) of
961	>	* tasks, and to process computations locally if this threshold is
962	>	* exceeded.  This method may be invoked only from within
963	>	* ForkJoinTask computations (as may be determined using method
964	>	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
965	>	* result in exceptions or errors, possibly including
966	>	* ClassCastException.  *
967		* @return the surplus number of tasks, which may be negative
968		*/
969	<	public static int surplus() {
970	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
969	>	public static int getSurplusQueuedTaskCount() {
970	>	return ((ForkJoinWorkerThread) Thread.currentThread())
971		.getEstimatedSurplusTaskCount();
972		}
973
974	<	// Extension kit
974	>	// Extension methods
975
976		/**
977	<	* Returns the result that would be returned by <tt>join</tt>, or
978	<	* null if this task is not known to have been completed.  This
979	<	* method is designed to aid debugging, as well as to support
980	<	* extensions. Its use in any other context is discouraged.
977	>	* Returns the result that would be returned by {@link #join}, even
978	>	* if this task completed abnormally, or {@code null} if this task
979	>	* is not known to have been completed.  This method is designed
980	>	* to aid debugging, as well as to support extensions. Its use in
981	>	* any other context is discouraged.
982		*
983	<	* @return the result, or null if not completed.
983	>	* @return the result, or {@code null} if not completed
984		*/
985		public abstract V getRawResult();
986
#	Line 865 | Line 999 | public abstract class ForkJoinTask<V> im
999		* called otherwise. The return value controls whether this task
1000		* is considered to be done normally. It may return false in
1001		* asynchronous actions that require explicit invocations of
1002	<	* <tt>complete</tt> to become joinable. It may throw exceptions
1002	>	* {@link #complete} to become joinable. It may throw exceptions
1003		* to indicate abnormal exit.
1004	<	* @return true if completed normally
1004	>	*
1005	>	* @return {@code true} if completed normally
1006		* @throws Error or RuntimeException if encountered during computation
1007		*/
1008		protected abstract boolean exec();
1009
1010	+	/**
1011	+	* Returns, but does not unschedule or execute, a task queued by
1012	+	* the current thread but not yet executed, if one is immediately
1013	+	* available. There is no guarantee that this task will actually
1014	+	* be polled or executed next. Conversely, this method may return
1015	+	* null even if a task exists but cannot be accessed without
1016	+	* contention with other threads.  This method is designed
1017	+	* primarily to support extensions, and is unlikely to be useful
1018	+	* otherwise.  This method may be invoked only from within
1019	+	* ForkJoinTask computations (as may be determined using method
1020	+	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1021	+	* result in exceptions or errors, possibly including
1022	+	* ClassCastException.
1023	+	*
1024	+	* @return the next task, or {@code null} if none are available
1025	+	*/
1026	+	protected static ForkJoinTask<?> peekNextLocalTask() {
1027	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1028	+	.peekTask();
1029	+	}
1030	+
1031	+	/**
1032	+	* Unschedules and returns, without executing, the next task
1033	+	* queued by the current thread but not yet executed.  This method
1034	+	* is designed primarily to support extensions, and is unlikely to
1035	+	* be useful otherwise.  This method may be invoked only from
1036	+	* within ForkJoinTask computations (as may be determined using
1037	+	* method {@link #inForkJoinPool}). Attempts to invoke in other
1038	+	* contexts result in exceptions or errors, possibly including
1039	+	* ClassCastException.
1040	+	*
1041	+	* @return the next task, or {@code null} if none are available
1042	+	*/
1043	+	protected static ForkJoinTask<?> pollNextLocalTask() {
1044	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1045	+	.pollLocalTask();
1046	+	}
1047	+
1048	+	/**
1049	+	* Unschedules and returns, without executing, the next task
1050	+	* queued by the current thread but not yet executed, if one is
1051	+	* available, or if not available, a task that was forked by some
1052	+	* other thread, if available. Availability may be transient, so a
1053	+	* {@code null} result does not necessarily imply quiescence
1054	+	* of the pool this task is operating in.  This method is designed
1055	+	* primarily to support extensions, and is unlikely to be useful
1056	+	* otherwise.  This method may be invoked only from within
1057	+	* ForkJoinTask computations (as may be determined using method
1058	+	* {@link #inForkJoinPool}). Attempts to invoke in other contexts
1059	+	* result in exceptions or errors, possibly including
1060	+	* ClassCastException.
1061	+	*
1062	+	* @return a task, or {@code null} if none are available
1063	+	*/
1064	+	protected static ForkJoinTask<?> pollTask() {
1065	+	return ((ForkJoinWorkerThread) Thread.currentThread())
1066	+	.pollTask();
1067	+	}
1068	+
1069	+	/**
1070	+	* Adaptor for Runnables. This implements RunnableFuture
1071	+	* to be compliant with AbstractExecutorService constraints
1072	+	* when used in ForkJoinPool.
1073	+	*/
1074	+	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1075	+	implements RunnableFuture<T> {
1076	+	final Runnable runnable;
1077	+	final T resultOnCompletion;
1078	+	T result;
1079	+	AdaptedRunnable(Runnable runnable, T result) {
1080	+	if (runnable == null) throw new NullPointerException();
1081	+	this.runnable = runnable;
1082	+	this.resultOnCompletion = result;
1083	+	}
1084	+	public T getRawResult() { return result; }
1085	+	public void setRawResult(T v) { result = v; }
1086	+	public boolean exec() {
1087	+	runnable.run();
1088	+	result = resultOnCompletion;
1089	+	return true;
1090	+	}
1091	+	public void run() { invoke(); }
1092	+	private static final long serialVersionUID = 5232453952276885070L;
1093	+	}
1094	+
1095	+	/**
1096	+	* Adaptor for Callables
1097	+	*/
1098	+	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1099	+	implements RunnableFuture<T> {
1100	+	final Callable<? extends T> callable;
1101	+	T result;
1102	+	AdaptedCallable(Callable<? extends T> callable) {
1103	+	if (callable == null) throw new NullPointerException();
1104	+	this.callable = callable;
1105	+	}
1106	+	public T getRawResult() { return result; }
1107	+	public void setRawResult(T v) { result = v; }
1108	+	public boolean exec() {
1109	+	try {
1110	+	result = callable.call();
1111	+	return true;
1112	+	} catch (Error err) {
1113	+	throw err;
1114	+	} catch (RuntimeException rex) {
1115	+	throw rex;
1116	+	} catch (Exception ex) {
1117	+	throw new RuntimeException(ex);
1118	+	}
1119	+	}
1120	+	public void run() { invoke(); }
1121	+	private static final long serialVersionUID = 2838392045355241008L;
1122	+	}
1123	+
1124	+	/**
1125	+	* Returns a new ForkJoinTask that performs the {@code run}
1126	+	* method of the given Runnable as its action, and returns a null
1127	+	* result upon {@code join}.
1128	+	*
1129	+	* @param runnable the runnable action
1130	+	* @return the task
1131	+	*/
1132	+	public static ForkJoinTask<?> adapt(Runnable runnable) {
1133	+	return new AdaptedRunnable<Void>(runnable, null);
1134	+	}
1135	+
1136	+	/**
1137	+	* Returns a new ForkJoinTask that performs the {@code run}
1138	+	* method of the given Runnable as its action, and returns the
1139	+	* given result upon {@code join}.
1140	+	*
1141	+	* @param runnable the runnable action
1142	+	* @param result the result upon completion
1143	+	* @return the task
1144	+	*/
1145	+	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1146	+	return new AdaptedRunnable<T>(runnable, result);
1147	+	}
1148	+
1149	+	/**
1150	+	* Returns a new ForkJoinTask that performs the {@code call}
1151	+	* method of the given Callable as its action, and returns its
1152	+	* result upon {@code join}, translating any checked
1153	+	* exceptions encountered into {@code RuntimeException}.
1154	+	*
1155	+	* @param callable the callable action
1156	+	* @return the task
1157	+	*/
1158	+	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1159	+	return new AdaptedCallable<T>(callable);
1160	+	}
1161	+
1162		// Serialization support
1163
1164		private static final long serialVersionUID = -7721805057305804111L;
#	Line 880 | Line 1167 | public abstract class ForkJoinTask<V> im
1167		* Save the state to a stream.
1168		*
1169		* @serialData the current run status and the exception thrown
1170	<	* during execution, or null if none.
1170	>	* during execution, or {@code null} if none
1171		* @param s the stream
1172		*/
1173		private void writeObject(java.io.ObjectOutputStream s)
#	Line 891 | Line 1178 | public abstract class ForkJoinTask<V> im
1178
1179		/**
1180		* Reconstitute the instance from a stream.
1181	+	*
1182		* @param s the stream
1183		*/
1184		private void readObject(java.io.ObjectInputStream s)
1185		throws java.io.IOException, ClassNotFoundException {
1186		s.defaultReadObject();
1187	<	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1187	>	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1188	>	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1189		Object ex = s.readObject();
1190		if (ex != null)
1191	<	setDoneExceptionally((Throwable)ex);
1191	>	setDoneExceptionally((Throwable) ex);
1192		}
1193
1194	<	// Temporary Unsafe mechanics for preliminary release
1194	>	// Unsafe mechanics
1195
1196	<	static final Unsafe _unsafe;
1197	<	static final long statusOffset;
1196	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1197	>	private static final long statusOffset =
1198	>	objectFieldOffset("status", ForkJoinTask.class);
1199
1200	<	static {
1200	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1201		try {
1202	<	if (ForkJoinTask.class.getClassLoader() != null) {
1203	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1204	<	f.setAccessible(true);
1205	<	_unsafe = (Unsafe)f.get(null);
1206	<	}
1207	<	else
1208	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
920	<	(ForkJoinTask.class.getDeclaredField("status"));
921	<	} catch (Exception ex) { throw new Error(ex); }
1202	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1203	>	} catch (NoSuchFieldException e) {
1204	>	// Convert Exception to corresponding Error
1205	>	NoSuchFieldError error = new NoSuchFieldError(field);
1206	>	error.initCause(e);
1207	>	throw error;
1208	>	}
1209		}
1210
1211	+	/**
1212	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1213	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1214	+	* into a jdk.
1215	+	*
1216	+	* @return a sun.misc.Unsafe
1217	+	*/
1218	+	private static sun.misc.Unsafe getUnsafe() {
1219	+	try {
1220	+	return sun.misc.Unsafe.getUnsafe();
1221	+	} catch (SecurityException se) {
1222	+	try {
1223	+	return java.security.AccessController.doPrivileged
1224	+	(new java.security
1225	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1226	+	public sun.misc.Unsafe run() throws Exception {
1227	+	java.lang.reflect.Field f = sun.misc
1228	+	.Unsafe.class.getDeclaredField("theUnsafe");
1229	+	f.setAccessible(true);
1230	+	return (sun.misc.Unsafe) f.get(null);
1231	+	}});
1232	+	} catch (java.security.PrivilegedActionException e) {
1233	+	throw new RuntimeException("Could not initialize intrinsics",
1234	+	e.getCause());
1235	+	}
1236	+	}
1237	+	}
1238		}

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