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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.34 by dl, Tue Aug 4 11:44:33 2009 UTC vs.
Revision 1.53 by dl, Wed Aug 11 18:45:12 2010 UTC

#	Line 56 | Line 56 | import java.util.WeakHashMap;
56		* exceptions such as {@code IOExceptions} to be thrown. However,
57		* computations may still encounter unchecked exceptions, that are
58		* rethrown to callers attempting to join them. These exceptions may
59	<	* additionally include RejectedExecutionExceptions stemming from
60	<	* internal resource exhaustion such as failure to allocate internal
61	<	* task queues.
59	>	* additionally include {@link RejectedExecutionException} stemming
60	>	* from internal resource exhaustion, such as failure to allocate
61	>	* internal task queues.
62		*
63		* <p>The primary method for awaiting completion and extracting
64		* results of a task is {@link #join}, but there are several variants:
65		* The {@link Future#get} methods support interruptible and/or timed
66		* waits for completion and report results using {@code Future}
67	<	* conventions. Method {@link #helpJoin} enables callers to actively
68	<	* execute other tasks while awaiting joins, which is sometimes more
69	<	* efficient but only applies when all subtasks are known to be
70	<	* strictly tree-structured. Method {@link #invoke} is semantically
71	<	* equivalent to {@code fork(); join()} but always attempts to
72	<	* begin execution in the current thread. The "<em>quiet</em>" forms
73	<	* of these methods do not extract results or report exceptions. These
67	>	* conventions. Method {@link #invoke} is semantically
68	>	* equivalent to {@code fork(); join()} but always attempts to begin
69	>	* execution in the current thread. The "<em>quiet</em>" forms of
70	>	* 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 execution status of tasks may be queried at several levels
78	+	* of detail: {@link #isDone} is true if a task completed in any way
79	+	* (including the case where a task was cancelled without executing);
80	+	* {@link #isCompletedNormally} is true if a task completed without
81	+	* cancellation or encountering an exception; {@link #isCancelled} is
82	+	* true if the task was cancelled (in which case {@link #getException}
83	+	* returns a {@link java.util.concurrent.CancellationException}); and
84	+	* {@link #isCompletedAbnormally} is true if a task was either
85	+	* cancelled or encountered an exception, in which case {@link
86	+	* #getException} will return either the encountered exception or
87	+	* {@link java.util.concurrent.CancellationException}.
88	+	*
89		* <p>The ForkJoinTask class is not usually directly subclassed.
90		* Instead, you subclass one of the abstract classes that support a
91		* particular style of fork/join processing, typically {@link
#	Line 111 | Line 120 | import java.util.WeakHashMap;
120		* improve throughput. If too small, then memory and internal task
121		* maintenance overhead may overwhelm processing.
122		*
123	<	* <p>This class provides {@code adapt} methods for {@link
124	<	* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that
125	<	* may be of use when mixing execution of ForkJoinTasks with other
126	<	* kinds of tasks. When all tasks are of this form, consider using a
118	<	* pool in {@link ForkJoinPool#setAsyncMode async mode}.
123	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
124	>	* and {@link Callable}, that may be of use when mixing execution of
125	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
126	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
127		*
128		* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
129		* used in extensions such as remote execution frameworks. It is
#	Line 127 | Line 135 | import java.util.WeakHashMap;
135		*/
136		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
137
138	<	/**
139	<	* Run control status bits packed into a single int to minimize
140	<	* footprint and to ensure atomicity (via CAS).  Status is
141	<	* initially zero, and takes on nonnegative values until
142	<	* completed, upon which status holds COMPLETED. CANCELLED, or
143	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
144	<	* blocking waits by other threads have SIGNAL_MASK bits set --
145	<	* bit 15 for external (nonFJ) waits, and the rest a count of
146	<	* waiting FJ threads.  (This representation relies on
147	<	* ForkJoinPool max thread limits). Completion of a stolen task
148	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
149	<	* though suboptimal for some purposes, we use basic builtin
150	<	* wait/notify to take advantage of "monitor inflation" in JVMs
151	<	* that we would otherwise need to emulate to avoid adding further
152	<	* per-task bookkeeping overhead. Note that bits 16-28 are
153	<	* currently unused. Also value 0x80000000 is available as spare
154	<	* completion value.
138	>	/*
139	>	* See the internal documentation of class ForkJoinPool for a
140	>	* general implementation overview.  ForkJoinTasks are mainly
141	>	* responsible for maintaining their "status" field amidst relays
142	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
143	>	* methods of this class are more-or-less layered into (1) basic
144	>	* status maintenance (2) execution and awaiting completion (3)
145	>	* user-level methods that additionally report results. This is
146	>	* sometimes hard to see because this file orders exported methods
147	>	* in a way that flows well in javadocs. In particular, most
148	>	* join mechanics are in method quietlyJoin, below.
149	>	*/
150	>
151	>	/*
152	>	* The status field holds run control status bits packed into a
153	>	* single int to minimize footprint and to ensure atomicity (via
154	>	* CAS).  Status is initially zero, and takes on nonnegative
155	>	* values until completed, upon which status holds value
156	>	* COMPLETED. CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
157	>	* waits by other threads have the SIGNAL bit set.  Completion of
158	>	* a stolen task with SIGNAL set awakens any waiters via
159	>	* notifyAll. Even though suboptimal for some purposes, we use
160	>	* basic builtin wait/notify to take advantage of "monitor
161	>	* inflation" in JVMs that we would otherwise need to emulate to
162	>	* avoid adding further per-task bookkeeping overhead.  We want
163	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
164	>	* techniques, so use some odd coding idioms that tend to avoid
165	>	* them.
166		*/
167	+
168	+	/** The run status of this task */
169		volatile int status; // accessed directly by pool and workers
170
171	<	static final int COMPLETION_MASK      = 0xe0000000;
172	<	static final int NORMAL               = 0xe0000000; // == mask
173	<	static final int CANCELLED            = 0xc0000000;
174	<	static final int EXCEPTIONAL          = 0xa0000000;
154	<	static final int SIGNAL_MASK          = 0x0000ffff;
155	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
156	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
171	>	private static final int NORMAL      = -1;
172	>	private static final int CANCELLED   = -2;
173	>	private static final int EXCEPTIONAL = -3;
174	>	private static final int SIGNAL      =  1;
175
176		/**
177		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 167 | Line 185 | public abstract class ForkJoinTask<V> im
185		Collections.synchronizedMap
186		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
187
188	<	// within-package utilities
188	>	// Maintaining completion status
189
190		/**
191	<	* Gets current worker thread, or null if not a worker thread.
192	<	*/
175	<	static ForkJoinWorkerThread getWorker() {
176	<	Thread t = Thread.currentThread();
177	<	return ((t instanceof ForkJoinWorkerThread) ?
178	<	(ForkJoinWorkerThread) t : null);
179	<	}
180	<
181	<	final boolean casStatus(int cmp, int val) {
182	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
183	<	}
184	<
185	<	/**
186	<	* Workaround for not being able to rethrow unchecked exceptions.
187	<	*/
188	<	static void rethrowException(Throwable ex) {
189	<	if (ex != null)
190	<	UNSAFE.throwException(ex);
191	<	}
192	<
193	<	// Setting completion status
194	<
195	<	/**
196	<	* Marks completion and wakes up threads waiting to join this task.
191	>	* Marks completion and wakes up threads waiting to join this task,
192	>	* also clearing signal request bits.
193		*
194		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
195		*/
196	<	final void setCompletion(int completion) {
197	<	ForkJoinPool pool = getPool();
198	<	if (pool != null) {
199	<	int s; // Clear signal bits while setting completion status
200	<	do {} while ((s = status) >= 0 && !casStatus(s, completion));
201	<
202	<	if ((s & SIGNAL_MASK) != 0) {
207	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
208	<	pool.updateRunningCount(s);
209	<	synchronized (this) { notifyAll(); }
196	>	private void setCompletion(int completion) {
197	>	int s;
198	>	while ((s = status) >= 0) {
199	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
200	>	if (s != 0)
201	>	synchronized (this) { notifyAll(); }
202	>	break;
203		}
204		}
212	–	else
213	–	externallySetCompletion(completion);
214	–	}
215	–
216	–	/**
217	–	* Version of setCompletion for non-FJ threads.  Leaves signal
218	–	* bits for unblocked threads to adjust, and always notifies.
219	–	*/
220	–	private void externallySetCompletion(int completion) {
221	–	int s;
222	–	do {} while ((s = status) >= 0 &&
223	–	!casStatus(s, (s & SIGNAL_MASK) | completion));
224	–	synchronized (this) { notifyAll(); }
225	–	}
226	–
227	–	/**
228	–	* Sets status to indicate normal completion.
229	–	*/
230	–	final void setNormalCompletion() {
231	–	// Try typical fast case -- single CAS, no signal, not already done.
232	–	// Manually expand casStatus to improve chances of inlining it
233	–	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
234	–	setCompletion(NORMAL);
205		}
206
237	–	// internal waiting and notification
238	–
207		/**
208	<	* Performs the actual monitor wait for awaitDone.
208	>	* Record exception and set exceptional completion
209	>	* @return status on exit
210		*/
211	<	private void doAwaitDone() {
212	<	// Minimize lock bias and in/de-flation effects by maximizing
213	<	// chances of waiting inside sync
245	<	try {
246	<	while (status >= 0)
247	<	synchronized (this) { if (status >= 0) wait(); }
248	<	} catch (InterruptedException ie) {
249	<	onInterruptedWait();
250	<	}
211	>	private void setExceptionalCompletion(Throwable rex) {
212	>	exceptionMap.put(this, rex);
213	>	setCompletion(EXCEPTIONAL);
214		}
215
216		/**
217	<	* Performs the actual timed monitor wait for awaitDone.
217	>	* Blocks a worker thread until completion. Called only by pool.
218		*/
219	<	private void doAwaitDone(long startTime, long nanos) {
220	<	synchronized (this) {
219	>	final void internalAwaitDone() {
220	>	int s;         // the odd construction reduces lock bias effects
221	>	while ((s = status) >= 0) {
222		try {
223	<	while (status >= 0) {
224	<	long nt = nanos - (System.nanoTime() - startTime);
225	<	if (nt <= 0)
262	<	break;
263	<	wait(nt / 1000000, (int) (nt % 1000000));
223	>	synchronized(this) {
224	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
225	>	wait();
226		}
227		} catch (InterruptedException ie) {
228	<	onInterruptedWait();
228	>	cancelIfTerminating();
229		}
230		}
231		}
232
271	–	// Awaiting completion
272	–
233		/**
234	<	* Sets status to indicate there is joiner, then waits for join,
275	<	* surrounded with pool notifications.
276	<	*
277	<	* @return status upon exit
234	>	* Blocks a non-worker-thread until completion.
235		*/
236	<	private int awaitDone(ForkJoinWorkerThread w,
280	<	boolean maintainParallelism) {
281	<	ForkJoinPool pool = (w == null) ? null : w.pool;
236	>	private void externalAwaitDone() {
237		int s;
238		while ((s = status) >= 0) {
239	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
240	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
241	<	doAwaitDone();
242	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
243	<	adjustPoolCountsOnUnblock(pool);
244	<	break;
245	<	}
246	<	}
247	<	return s;
248	<	}
249	<
250	<	/**
296	<	* Timed version of awaitDone
297	<	*
298	<	* @return status upon exit
299	<	*/
300	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
301	<	ForkJoinPool pool = (w == null) ? null : w.pool;
302	<	int s;
303	<	while ((s = status) >= 0) {
304	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
305	<	long startTime = System.nanoTime();
306	<	if (pool == null || !pool.preJoin(this, false))
307	<	doAwaitDone(startTime, nanos);
308	<	if ((s = status) >= 0) {
309	<	adjustPoolCountsOnCancelledWait(pool);
310	<	s = status;
311	<	}
312	<	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
313	<	adjustPoolCountsOnUnblock(pool);
314	<	break;
315	<	}
316	<	}
317	<	return s;
318	<	}
319	<
320	<	/**
321	<	* Notifies pool that thread is unblocked. Called by signalled
322	<	* threads when woken by non-FJ threads (which is atypical).
323	<	*/
324	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
325	<	int s;
326	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
327	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
328	<	pool.updateRunningCount(s);
329	<	}
330	<
331	<	/**
332	<	* Notifies pool to adjust counts on cancelled or timed out wait.
333	<	*/
334	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
335	<	if (pool != null) {
336	<	int s;
337	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
338	<	if (casStatus(s, s - 1)) {
339	<	pool.updateRunningCount(1);
239	>	synchronized(this) {
240	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
241	>	boolean interrupted = false;
242	>	while (status >= 0) {
243	>	try {
244	>	wait();
245	>	} catch (InterruptedException ie) {
246	>	interrupted = true;
247	>	}
248	>	}
249	>	if (interrupted)
250	>	Thread.currentThread().interrupt();
251		break;
252		}
253		}
#	Line 344 | Line 255 | public abstract class ForkJoinTask<V> im
255		}
256
257		/**
258	<	* Handles interruptions during waits.
259	<	*/
260	<	private void onInterruptedWait() {
350	<	ForkJoinWorkerThread w = getWorker();
351	<	if (w == null)
352	<	Thread.currentThread().interrupt(); // re-interrupt
353	<	else if (w.isTerminating())
354	<	cancelIgnoringExceptions();
355	<	// else if FJworker, ignore interrupt
356	<	}
357	<
358	<	// Recording and reporting exceptions
359	<
360	<	private void setDoneExceptionally(Throwable rex) {
361	<	exceptionMap.put(this, rex);
362	<	setCompletion(EXCEPTIONAL);
363	<	}
364	<
365	<	/**
366	<	* Throws the exception associated with status s.
367	<	*
368	<	* @throws the exception
369	<	*/
370	<	private void reportException(int s) {
371	<	if ((s &= COMPLETION_MASK) < NORMAL) {
372	<	if (s == CANCELLED)
373	<	throw new CancellationException();
374	<	else
375	<	rethrowException(exceptionMap.get(this));
376	<	}
377	<	}
378	<
379	<	/**
380	<	* Returns result or throws exception using j.u.c.Future conventions.
381	<	* Only call when {@code isDone} known to be true.
382	<	*/
383	<	private V reportFutureResult()
384	<	throws ExecutionException, InterruptedException {
385	<	if (Thread.interrupted())
386	<	throw new InterruptedException();
387	<	int s = status & COMPLETION_MASK;
388	<	if (s < NORMAL) {
389	<	Throwable ex;
390	<	if (s == CANCELLED)
391	<	throw new CancellationException();
392	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
393	<	throw new ExecutionException(ex);
394	<	}
395	<	return getRawResult();
396	<	}
397	<
398	<	/**
399	<	* Returns result or throws exception using j.u.c.Future conventions
400	<	* with timeouts.
401	<	*/
402	<	private V reportTimedFutureResult()
403	<	throws InterruptedException, ExecutionException, TimeoutException {
404	<	if (Thread.interrupted())
405	<	throw new InterruptedException();
406	<	Throwable ex;
407	<	int s = status & COMPLETION_MASK;
408	<	if (s == NORMAL)
409	<	return getRawResult();
410	<	if (s == CANCELLED)
411	<	throw new CancellationException();
412	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
413	<	throw new ExecutionException(ex);
414	<	throw new TimeoutException();
415	<	}
416	<
417	<	// internal execution methods
418	<
419	<	/**
420	<	* Calls exec, recording completion, and rethrowing exception if
421	<	* encountered. Caller should normally check status before calling.
422	<	*
423	<	* @return true if completed normally
424	<	*/
425	<	private boolean tryExec() {
426	<	try { // try block must contain only call to exec
427	<	if (!exec())
428	<	return false;
429	<	} catch (Throwable rex) {
430	<	setDoneExceptionally(rex);
431	<	rethrowException(rex);
432	<	return false; // not reached
433	<	}
434	<	setNormalCompletion();
435	<	return true;
436	<	}
437	<
438	<	/**
439	<	* Main execution method used by worker threads. Invokes
440	<	* base computation unless already complete.
258	>	* Unless done, calls exec and records status if completed, but
259	>	* doesn't wait for completion otherwise. Primary execution method
260	>	* for ForkJoinWorkerThread.
261		*/
262		final void quietlyExec() {
443	–	if (status >= 0) {
444	–	try {
445	–	if (!exec())
446	–	return;
447	–	} catch (Throwable rex) {
448	–	setDoneExceptionally(rex);
449	–	return;
450	–	}
451	–	setNormalCompletion();
452	–	}
453	–	}
454	–
455	–	/**
456	–	* Calls exec(), recording but not rethrowing exception.
457	–	* Caller should normally check status before calling.
458	–	*
459	–	* @return true if completed normally
460	–	*/
461	–	private boolean tryQuietlyInvoke() {
263		try {
264	<	if (!exec())
265	<	return false;
264	>	if (status < 0 || !exec())
265	>	return;
266		} catch (Throwable rex) {
267	<	setDoneExceptionally(rex);
268	<	return false;
468	<	}
469	<	setNormalCompletion();
470	<	return true;
471	<	}
472	<
473	<	/**
474	<	* Cancels, ignoring any exceptions it throws.
475	<	*/
476	<	final void cancelIgnoringExceptions() {
477	<	try {
478	<	cancel(false);
479	<	} catch (Throwable ignore) {
267	>	setExceptionalCompletion(rex);
268	>	return;
269		}
270	<	}
482	<
483	<	/**
484	<	* Main implementation of helpJoin
485	<	*/
486	<	private int busyJoin(ForkJoinWorkerThread w) {
487	<	int s;
488	<	ForkJoinTask<?> t;
489	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
490	<	t.quietlyExec();
491	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
270	>	setCompletion(NORMAL); // must be outside try block
271		}
272
273		// public methods
#	Line 497 | Line 276 | public abstract class ForkJoinTask<V> im
276		* Arranges to asynchronously execute this task.  While it is not
277		* necessarily enforced, it is a usage error to fork a task more
278		* than once unless it has completed and been reinitialized.
279	+	* Subsequent modifications to the state of this task or any data
280	+	* it operates on are not necessarily consistently observable by
281	+	* any thread other than the one executing it unless preceded by a
282	+	* call to {@link #join} or related methods, or a call to {@link
283	+	* #isDone} returning {@code true}.
284		*
285		* <p>This method may be invoked only from within {@code
286		* ForkJoinTask} computations (as may be determined using method
#	Line 513 | Line 297 | public abstract class ForkJoinTask<V> im
297		}
298
299		/**
300	<	* Returns the result of the computation when it is ready.
300	>	* Returns the result of the computation when it {@link #isDone is done}.
301		* This method differs from {@link #get()} in that
302		* abnormal completion results in {@code RuntimeException} or
303		* {@code Error}, not {@code ExecutionException}.
#	Line 521 | Line 305 | public abstract class ForkJoinTask<V> im
305		* @return the computed result
306		*/
307		public final V join() {
308	<	ForkJoinWorkerThread w = getWorker();
309	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
310	<	reportException(awaitDone(w, true));
308	>	quietlyJoin();
309	>	Throwable ex;
310	>	if (status < NORMAL && (ex = getException()) != null)
311	>	UNSAFE.throwException(ex);
312		return getRawResult();
313		}
314
#	Line 535 | Line 320 | public abstract class ForkJoinTask<V> im
320		* @return the computed result
321		*/
322		public final V invoke() {
323	<	if (status >= 0 && tryExec())
324	<	return getRawResult();
325	<	else
326	<	return join();
323	>	quietlyInvoke();
324	>	Throwable ex;
325	>	if (status < NORMAL && (ex = getException()) != null)
326	>	UNSAFE.throwException(ex);
327	>	return getRawResult();
328		}
329
330		/**
331		* Forks the given tasks, returning when {@code isDone} holds for
332		* each task or an (unchecked) exception is encountered, in which
333	<	* case the exception is rethrown.  If more than one task
334	<	* encounters an exception, then this method throws any one of
335	<	* these exceptions.  The individual status of each task may be
333	>	* case the exception is rethrown.  If either task encounters an
334	>	* exception, the other one may be, but is not guaranteed to be,
335	>	* cancelled.  If both tasks throw an exception, then this method
336	>	* throws one of them.  The individual status of each task may be
337		* checked using {@link #getException()} and related methods.
338		*
339		* <p>This method may be invoked only from within {@code
#	Line 597 | Line 384 | public abstract class ForkJoinTask<V> im
384		t.fork();
385		else {
386		t.quietlyInvoke();
387	<	if (ex == null)
387	>	if (ex == null && t.status < NORMAL)
388		ex = t.getException();
389		}
390		}
#	Line 608 | Line 395 | public abstract class ForkJoinTask<V> im
395		t.cancel(false);
396		else {
397		t.quietlyJoin();
398	<	if (ex == null)
398	>	if (ex == null && t.status < NORMAL)
399		ex = t.getException();
400		}
401		}
402		}
403		if (ex != null)
404	<	rethrowException(ex);
404	>	UNSAFE.throwException(ex);
405		}
406
407		/**
#	Line 659 | Line 446 | public abstract class ForkJoinTask<V> im
446		t.fork();
447		else {
448		t.quietlyInvoke();
449	<	if (ex == null)
449	>	if (ex == null && t.status < NORMAL)
450		ex = t.getException();
451		}
452		}
#	Line 670 | Line 457 | public abstract class ForkJoinTask<V> im
457		t.cancel(false);
458		else {
459		t.quietlyJoin();
460	<	if (ex == null)
460	>	if (ex == null && t.status < NORMAL)
461		ex = t.getException();
462		}
463		}
464		}
465		if (ex != null)
466	<	rethrowException(ex);
466	>	UNSAFE.throwException(ex);
467		return tasks;
468		}
469
#	Line 706 | Line 493 | public abstract class ForkJoinTask<V> im
493		*/
494		public boolean cancel(boolean mayInterruptIfRunning) {
495		setCompletion(CANCELLED);
496	<	return (status & COMPLETION_MASK) == CANCELLED;
496	>	return status == CANCELLED;
497		}
498
499		/**
500	<	* Returns {@code true} if the computation performed by this task
501	<	* has completed (or has been cancelled).
502	<	*
503	<	* @return {@code true} if this computation has completed
500	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
501	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
502	>	* exceptions, but if it does anyway, we have no recourse during
503	>	* shutdown, so guard against this case.
504		*/
505	<	public final boolean isDone() {
506	<	return status < 0;
505	>	final void cancelIgnoringExceptions() {
506	>	try {
507	>	cancel(false);
508	>	} catch (Throwable ignore) {
509	>	}
510		}
511
512		/**
513	<	* Returns {@code true} if this task was cancelled.
724	<	*
725	<	* @return {@code true} if this task was cancelled
513	>	* Cancels ignoring exceptions if worker is terminating
514		*/
515	+	final void cancelIfTerminating() {
516	+	Thread t = Thread.currentThread();
517	+	if ((t instanceof ForkJoinWorkerThread) &&
518	+	((ForkJoinWorkerThread) t).isTerminating()) {
519	+	try {
520	+	cancel(false);
521	+	} catch (Throwable ignore) {
522	+	}
523	+	}
524	+	}
525	+
526	+	public final boolean isDone() {
527	+	return status < 0;
528	+	}
529	+
530		public final boolean isCancelled() {
531	<	return (status & COMPLETION_MASK) == CANCELLED;
531	>	return status == CANCELLED;
532		}
533
534		/**
#	Line 734 | Line 537 | public abstract class ForkJoinTask<V> im
537		* @return {@code true} if this task threw an exception or was cancelled
538		*/
539		public final boolean isCompletedAbnormally() {
540	<	return (status & COMPLETION_MASK) < NORMAL;
540	>	return status < NORMAL;
541		}
542
543		/**
#	Line 745 | Line 548 | public abstract class ForkJoinTask<V> im
548		* exception and was not cancelled
549		*/
550		public final boolean isCompletedNormally() {
551	<	return (status & COMPLETION_MASK) == NORMAL;
749	<	}
750	<
751	<	/**
752	<	* Returns {@code true} if this task threw an exception.
753	<	*
754	<	* @return {@code true} if this task threw an exception
755	<	*/
756	<	public final boolean isCompletedExceptionally() {
757	<	return (status & COMPLETION_MASK) == EXCEPTIONAL;
551	>	return status == NORMAL;
552		}
553
554		/**
#	Line 765 | Line 559 | public abstract class ForkJoinTask<V> im
559		* @return the exception, or {@code null} if none
560		*/
561		public final Throwable getException() {
562	<	int s = status & COMPLETION_MASK;
563	<	if (s >= NORMAL)
564	<	return null;
565	<	if (s == CANCELLED)
772	<	return new CancellationException();
773	<	return exceptionMap.get(this);
562	>	int s = status;
563	>	return ((s >= NORMAL)    ? null :
564	>	(s == CANCELLED) ? new CancellationException() :
565	>	exceptionMap.get(this));
566		}
567
568		/**
#	Line 783 | Line 575 | public abstract class ForkJoinTask<V> im
575		* overridable, but overridden versions must invoke {@code super}
576		* implementation to maintain guarantees.
577		*
578	<	* @param ex the exception to throw. If this exception is
579	<	* not a RuntimeException or Error, the actual exception thrown
580	<	* will be a RuntimeException with cause ex.
578	>	* @param ex the exception to throw. If this exception is not a
579	>	* {@code RuntimeException} or {@code Error}, the actual exception
580	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
581		*/
582		public void completeExceptionally(Throwable ex) {
583	<	setDoneExceptionally((ex instanceof RuntimeException) ||
584	<	(ex instanceof Error) ? ex :
585	<	new RuntimeException(ex));
583	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
584	>	(ex instanceof Error) ? ex :
585	>	new RuntimeException(ex));
586		}
587
588		/**
#	Line 809 | Line 601 | public abstract class ForkJoinTask<V> im
601		try {
602		setRawResult(value);
603		} catch (Throwable rex) {
604	<	setDoneExceptionally(rex);
604	>	setExceptionalCompletion(rex);
605		return;
606		}
607	<	setNormalCompletion();
607	>	setCompletion(NORMAL);
608		}
609
610		public final V get() throws InterruptedException, ExecutionException {
611	<	ForkJoinWorkerThread w = getWorker();
612	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
613	<	awaitDone(w, true);
614	<	return reportFutureResult();
611	>	quietlyJoin();
612	>	if (Thread.interrupted())
613	>	throw new InterruptedException();
614	>	int s = status;
615	>	if (s < NORMAL) {
616	>	Throwable ex;
617	>	if (s == CANCELLED)
618	>	throw new CancellationException();
619	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
620	>	throw new ExecutionException(ex);
621	>	}
622	>	return getRawResult();
623		}
624
625		public final V get(long timeout, TimeUnit unit)
626		throws InterruptedException, ExecutionException, TimeoutException {
627	<	long nanos = unit.toNanos(timeout);
628	<	ForkJoinWorkerThread w = getWorker();
629	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
630	<	awaitDone(w, nanos);
631	<	return reportTimedFutureResult();
632	<	}
633	<
834	<	/**
835	<	* Possibly executes other tasks until this task is ready, then
836	<	* returns the result of the computation.  This method may be more
837	<	* efficient than {@code join}, but is only applicable when
838	<	* there are no potential dependencies between continuation of the
839	<	* current task and that of any other task that might be executed
840	<	* while helping. (This usually holds for pure divide-and-conquer
841	<	* tasks).
842	<	*
843	<	* <p>This method may be invoked only from within {@code
844	<	* ForkJoinTask} computations (as may be determined using method
845	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
846	<	* result in exceptions or errors, possibly including {@code
847	<	* ClassCastException}.
848	<	*
849	<	* @return the computed result
850	<	*/
851	<	public final V helpJoin() {
852	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
853	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
854	<	reportException(busyJoin(w));
855	<	return getRawResult();
856	<	}
857	<
858	<	/**
859	<	* Possibly executes other tasks until this task is ready.  This
860	<	* method may be useful when processing collections of tasks when
861	<	* some have been cancelled or otherwise known to have aborted.
862	<	*
863	<	* <p>This method may be invoked only from within {@code
864	<	* ForkJoinTask} computations (as may be determined using method
865	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
866	<	* result in exceptions or errors, possibly including {@code
867	<	* ClassCastException}.
868	<	*/
869	<	public final void quietlyHelpJoin() {
870	<	if (status >= 0) {
871	<	ForkJoinWorkerThread w =
872	<	(ForkJoinWorkerThread) Thread.currentThread();
873	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
874	<	busyJoin(w);
627	>	Thread t = Thread.currentThread();
628	>	ForkJoinPool pool;
629	>	if (t instanceof ForkJoinWorkerThread) {
630	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
631	>	if (status >= 0 && w.unpushTask(this))
632	>	quietlyExec();
633	>	pool = w.pool;
634		}
635	+	else
636	+	pool = null;
637	+	/*
638	+	* Timed wait loop intermixes cases for FJ (pool != null) and
639	+	* non FJ threads. For FJ, decrement pool count but don't try
640	+	* for replacement; increment count on completion. For non-FJ,
641	+	* deal with interrupts. This is messy, but a little less so
642	+	* than is splitting the FJ and nonFJ cases.
643	+	*/
644	+	boolean interrupted = false;
645	+	boolean dec = false; // true if pool count decremented
646	+	for (;;) {
647	+	if (Thread.interrupted() && pool == null) {
648	+	interrupted = true;
649	+	break;
650	+	}
651	+	int s = status;
652	+	if (s < 0)
653	+	break;
654	+	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
655	+	long startTime = System.nanoTime();
656	+	long nanos = unit.toNanos(timeout);
657	+	long nt; // wait time
658	+	while (status >= 0 &&
659	+	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
660	+	if (pool != null && !dec)
661	+	dec = pool.tryDecrementRunningCount();
662	+	else {
663	+	long ms = nt / 1000000;
664	+	int ns = (int) (nt % 1000000);
665	+	try {
666	+	synchronized(this) {
667	+	if (status >= 0)
668	+	wait(ms, ns);
669	+	}
670	+	} catch (InterruptedException ie) {
671	+	if (pool != null)
672	+	cancelIfTerminating();
673	+	else {
674	+	interrupted = true;
675	+	break;
676	+	}
677	+	}
678	+	}
679	+	}
680	+	break;
681	+	}
682	+	}
683	+	if (pool != null && dec)
684	+	pool.incrementRunningCount();
685	+	if (interrupted)
686	+	throw new InterruptedException();
687	+	int es = status;
688	+	if (es != NORMAL) {
689	+	Throwable ex;
690	+	if (es == CANCELLED)
691	+	throw new CancellationException();
692	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
693	+	throw new ExecutionException(ex);
694	+	throw new TimeoutException();
695	+	}
696	+	return getRawResult();
697		}
698
699		/**
700	<	* Joins this task, without returning its result or throwing an
700	>	* Joins this task, without returning its result or throwing its
701		* exception. This method may be useful when processing
702		* collections of tasks when some have been cancelled or otherwise
703		* known to have aborted.
704		*/
705		public final void quietlyJoin() {
706	<	if (status >= 0) {
707	<	ForkJoinWorkerThread w = getWorker();
708	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
709	<	awaitDone(w, true);
706	>	Thread t;
707	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
708	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
709	>	if (status >= 0) {
710	>	if (w.unpushTask(this)) {
711	>	boolean completed;
712	>	try {
713	>	completed = exec();
714	>	} catch (Throwable rex) {
715	>	setExceptionalCompletion(rex);
716	>	return;
717	>	}
718	>	if (completed) {
719	>	setCompletion(NORMAL);
720	>	return;
721	>	}
722	>	}
723	>	w.joinTask(this);
724	>	}
725		}
726	+	else
727	+	externalAwaitDone();
728		}
729
730		/**
731		* Commences performing this task and awaits its completion if
732	<	* necessary, without returning its result or throwing an
732	>	* necessary, without returning its result or throwing its
733		* exception. This method may be useful when processing
734		* collections of tasks when some have been cancelled or otherwise
735		* known to have aborted.
736		*/
737		public final void quietlyInvoke() {
738	<	if (status >= 0 && !tryQuietlyInvoke())
739	<	quietlyJoin();
738	>	if (status >= 0) {
739	>	boolean completed;
740	>	try {
741	>	completed = exec();
742	>	} catch (Throwable rex) {
743	>	setExceptionalCompletion(rex);
744	>	return;
745	>	}
746	>	if (completed)
747	>	setCompletion(NORMAL);
748	>	else
749	>	quietlyJoin();
750	>	}
751		}
752
753		/**
#	Line 930 | Line 779 | public abstract class ForkJoinTask<V> im
779		* pre-constructed trees of subtasks in loops.
780		*/
781		public void reinitialize() {
782	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
782	>	if (status == EXCEPTIONAL)
783		exceptionMap.remove(this);
784		status = 0;
785		}
#	Line 1220 | Line 1069 | public abstract class ForkJoinTask<V> im
1069		private static final long serialVersionUID = -7721805057305804111L;
1070
1071		/**
1072	<	* Save the state to a stream.
1072	>	* Saves the state to a stream.
1073		*
1074		* @serialData the current run status and the exception thrown
1075		* during execution, or {@code null} if none
#	Line 1233 | Line 1082 | public abstract class ForkJoinTask<V> im
1082		}
1083
1084		/**
1085	<	* Reconstitute the instance from a stream.
1085	>	* Reconstitutes the instance from a stream.
1086		*
1087		* @param s the stream
1088		*/
1089		private void readObject(java.io.ObjectInputStream s)
1090		throws java.io.IOException, ClassNotFoundException {
1091		s.defaultReadObject();
1243	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1244	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1092		Object ex = s.readObject();
1093		if (ex != null)
1094	<	setDoneExceptionally((Throwable) ex);
1094	>	setExceptionalCompletion((Throwable) ex);
1095		}
1096
1097		// Unsafe mechanics

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