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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.42 by dl, Thu Aug 6 23:08:50 2009 UTC vs.
Revision 1.52 by dl, Sat Jul 24 20:28:18 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
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
#	Line 125 | Line 122 | import java.util.WeakHashMap;
122		*
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
126	<	* are of this form, consider using a pool in
130	<	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
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 139 | 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.
148	>	*/
149	>
150	>	/*
151	>	* The status field holds run control status bits packed into a
152	>	* single int to minimize footprint and to ensure atomicity (via
153	>	* CAS).  Status is initially zero, and takes on nonnegative
154	>	* values until completed, upon which status holds value
155	>	* COMPLETED. CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
156	>	* waits by other threads have the SIGNAL bit set.  Completion of
157	>	* a stolen task with SIGNAL set awakens any waiters via
158	>	* notifyAll. Even though suboptimal for some purposes, we use
159	>	* basic builtin wait/notify to take advantage of "monitor
160	>	* inflation" in JVMs that we would otherwise need to emulate to
161	>	* avoid adding further per-task bookkeeping overhead.  We want
162	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
163	>	* techniques, so use some odd coding idioms that tend to avoid
164	>	* them.
165		*/
166	+
167	+	/** Run status of this task */
168		volatile int status; // accessed directly by pool and workers
169
170	<	static final int COMPLETION_MASK      = 0xe0000000;
171	<	static final int NORMAL               = 0xe0000000; // == mask
172	<	static final int CANCELLED            = 0xc0000000;
173	<	static final int EXCEPTIONAL          = 0xa0000000;
166	<	static final int SIGNAL_MASK          = 0x0000ffff;
167	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
168	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
170	>	private static final int NORMAL      = -1;
171	>	private static final int CANCELLED   = -2;
172	>	private static final int EXCEPTIONAL = -3;
173	>	private static final int SIGNAL      =  1;
174
175		/**
176		* Table of exceptions thrown by tasks, to enable reporting by
#	Line 179 | Line 184 | public abstract class ForkJoinTask<V> im
184		Collections.synchronizedMap
185		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
186
187	<	// within-package utilities
183	<
184	<	/**
185	<	* Gets current worker thread, or null if not a worker thread.
186	<	*/
187	<	static ForkJoinWorkerThread getWorker() {
188	<	Thread t = Thread.currentThread();
189	<	return ((t instanceof ForkJoinWorkerThread) ?
190	<	(ForkJoinWorkerThread) t : null);
191	<	}
192	<
193	<	final boolean casStatus(int cmp, int val) {
194	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
195	<	}
187	>	// Maintaining completion status
188
189		/**
190	<	* Workaround for not being able to rethrow unchecked exceptions.
191	<	*/
200	<	static void rethrowException(Throwable ex) {
201	<	if (ex != null)
202	<	UNSAFE.throwException(ex);
203	<	}
204	<
205	<	// Setting completion status
206	<
207	<	/**
208	<	* Marks completion and wakes up threads waiting to join this task.
190	>	* Marks completion and wakes up threads waiting to join this task,
191	>	* also clearing signal request bits.
192		*
193		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
194	+	* @return status on exit
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) {
219	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
220	<	pool.updateRunningCount(s);
221	<	synchronized (this) { notifyAll(); }
196	>	private int 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	>	return completion;
203		}
204		}
205	<	else
225	<	externallySetCompletion(completion);
226	<	}
227	<
228	<	/**
229	<	* Version of setCompletion for non-FJ threads.  Leaves signal
230	<	* bits for unblocked threads to adjust, and always notifies.
231	<	*/
232	<	private void externallySetCompletion(int completion) {
233	<	int s;
234	<	do {} while ((s = status) >= 0 &&
235	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
236	<	synchronized (this) { notifyAll(); }
237	<	}
238	<
239	<	/**
240	<	* Sets status to indicate normal completion.
241	<	*/
242	<	final void setNormalCompletion() {
243	<	// Try typical fast case -- single CAS, no signal, not already done.
244	<	// Manually expand casStatus to improve chances of inlining it
245	<	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
246	<	setCompletion(NORMAL);
205	>	return s;
206		}
207
249	–	// internal waiting and notification
250	–
208		/**
209	<	* Performs the actual monitor wait for awaitDone.
209	>	* Record exception and set exceptional completion
210	>	* @return status on exit
211		*/
212	<	private void doAwaitDone() {
213	<	// Minimize lock bias and in/de-flation effects by maximizing
214	<	// chances of waiting inside sync
257	<	try {
258	<	while (status >= 0)
259	<	synchronized (this) { if (status >= 0) wait(); }
260	<	} catch (InterruptedException ie) {
261	<	onInterruptedWait();
262	<	}
212	>	private int setExceptionalCompletion(Throwable rex) {
213	>	exceptionMap.put(this, rex);
214	>	return setCompletion(EXCEPTIONAL);
215		}
216
217		/**
218	<	* Performs the actual timed monitor wait for awaitDone.
218	>	* Blocks a worker thread until completion. Called only by pool.
219		*/
220	<	private void doAwaitDone(long startTime, long nanos) {
221	<	synchronized (this) {
220	>	final void internalAwaitDone() {
221	>	int s;         // the odd construction reduces lock bias effects
222	>	while ((s = status) >= 0) {
223		try {
224	<	while (status >= 0) {
225	<	long nt = nanos - (System.nanoTime() - startTime);
226	<	if (nt <= 0)
274	<	break;
275	<	wait(nt / 1000000, (int) (nt % 1000000));
224	>	synchronized(this) {
225	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
226	>	wait();
227		}
228		} catch (InterruptedException ie) {
229	<	onInterruptedWait();
279	<	}
280	<	}
281	<	}
282	<
283	<	// Awaiting completion
284	<
285	<	/**
286	<	* Sets status to indicate there is joiner, then waits for join,
287	<	* surrounded with pool notifications.
288	<	*
289	<	* @return status upon exit
290	<	*/
291	<	private int awaitDone(ForkJoinWorkerThread w,
292	<	boolean maintainParallelism) {
293	<	ForkJoinPool pool = (w == null) ? null : w.pool;
294	<	int s;
295	<	while ((s = status) >= 0) {
296	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
297	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
298	<	doAwaitDone();
299	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
300	<	adjustPoolCountsOnUnblock(pool);
301	<	break;
229	>	cancelIfTerminating();
230		}
231		}
304	–	return s;
232		}
233
234		/**
235	<	* Timed version of awaitDone
236	<	*
310	<	* @return status upon exit
235	>	* Blocks a non-worker-thread until completion.
236	>	* @return status on exit
237		*/
238	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
313	<	ForkJoinPool pool = (w == null) ? null : w.pool;
238	>	private int externalAwaitDone() {
239		int s;
240		while ((s = status) >= 0) {
241	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
242	<	long startTime = System.nanoTime();
243	<	if (pool == null || !pool.preJoin(this, false))
244	<	doAwaitDone(startTime, nanos);
245	<	if ((s = status) >= 0) {
246	<	adjustPoolCountsOnCancelledWait(pool);
247	<	s = status;
241	>	synchronized(this) {
242	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){
243	>	boolean interrupted = false;
244	>	while ((s = status) >= 0) {
245	>	try {
246	>	wait();
247	>	} catch (InterruptedException ie) {
248	>	interrupted = true;
249	>	}
250	>	}
251	>	if (interrupted)
252	>	Thread.currentThread().interrupt();
253	>	break;
254		}
324	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
325	–	adjustPoolCountsOnUnblock(pool);
326	–	break;
255		}
256		}
257		return s;
258		}
259
260		/**
261	<	* Notifies pool that thread is unblocked. Called by signalled
262	<	* threads when woken by non-FJ threads (which is atypical).
261	>	* Unless done, calls exec and records status if completed, but
262	>	* doesn't wait for completion otherwise. Primary execution method
263	>	* for ForkJoinWorkerThread.
264		*/
265	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
266	<	int s;
267	<	do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
268	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
269	<	pool.updateRunningCount(s);
265	>	final void tryExec() {
266	>	try {
267	>	if (status < 0 || !exec())
268	>	return;
269	>	} catch (Throwable rex) {
270	>	setExceptionalCompletion(rex);
271	>	return;
272	>	}
273	>	setCompletion(NORMAL); // must be outside try block
274		}
275
276		/**
277	<	* Notifies pool to adjust counts on cancelled or timed out wait.
278	<	*/
279	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
280	<	if (pool != null) {
281	<	int s;
282	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
283	<	if (casStatus(s, s - 1)) {
284	<	pool.updateRunningCount(1);
285	<	break;
277	>	* If not done and this task is next in worker queue, runs it,
278	>	* else waits for it.
279	>	* @return status on exit
280	>	*/
281	>	private int doJoin() {
282	>	int stat;
283	>	Thread t;
284	>	ForkJoinWorkerThread w;
285	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
286	>	if ((stat = status) < 0)
287	>	return stat;
288	>	if ((w = (ForkJoinWorkerThread) t).unpushTask(this)) {
289	>	boolean completed;
290	>	try {
291	>	completed = exec();
292	>	} catch (Throwable rex) {
293	>	return setExceptionalCompletion(rex);
294		}
295	+	if (completed)
296	+	return setCompletion(NORMAL);
297		}
298	+	return w.joinTask(this);
299		}
300	+	return externalAwaitDone();
301		}
302
303		/**
304	<	* Handles interruptions during waits.
305	<	*/
306	<	private void onInterruptedWait() {
362	<	ForkJoinWorkerThread w = getWorker();
363	<	if (w == null)
364	<	Thread.currentThread().interrupt(); // re-interrupt
365	<	else if (w.isTerminating())
366	<	cancelIgnoringExceptions();
367	<	// else if FJworker, ignore interrupt
368	<	}
369	<
370	<	// Recording and reporting exceptions
371	<
372	<	private void setDoneExceptionally(Throwable rex) {
373	<	exceptionMap.put(this, rex);
374	<	setCompletion(EXCEPTIONAL);
375	<	}
376	<
377	<	/**
378	<	* Throws the exception associated with status s.
379	<	*
380	<	* @throws the exception
381	<	*/
382	<	private void reportException(int s) {
383	<	if ((s &= COMPLETION_MASK) < NORMAL) {
384	<	if (s == CANCELLED)
385	<	throw new CancellationException();
386	<	else
387	<	rethrowException(exceptionMap.get(this));
388	<	}
389	<	}
390	<
391	<	/**
392	<	* Returns result or throws exception using j.u.c.Future conventions.
393	<	* Only call when {@code isDone} known to be true or thread known
394	<	* to be interrupted.
395	<	*/
396	<	private V reportFutureResult()
397	<	throws InterruptedException, ExecutionException {
398	<	if (Thread.interrupted())
399	<	throw new InterruptedException();
400	<	int s = status & COMPLETION_MASK;
401	<	if (s < NORMAL) {
402	<	Throwable ex;
403	<	if (s == CANCELLED)
404	<	throw new CancellationException();
405	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
406	<	throw new ExecutionException(ex);
407	<	}
408	<	return getRawResult();
409	<	}
410	<
411	<	/**
412	<	* Returns result or throws exception using j.u.c.Future conventions
413	<	* with timeouts.
414	<	*/
415	<	private V reportTimedFutureResult()
416	<	throws InterruptedException, ExecutionException, TimeoutException {
417	<	if (Thread.interrupted())
418	<	throw new InterruptedException();
419	<	Throwable ex;
420	<	int s = status & COMPLETION_MASK;
421	<	if (s == NORMAL)
422	<	return getRawResult();
423	<	else if (s == CANCELLED)
424	<	throw new CancellationException();
425	<	else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
426	<	throw new ExecutionException(ex);
427	<	else
428	<	throw new TimeoutException();
429	<	}
430	<
431	<	// internal execution methods
432	<
433	<	/**
434	<	* Calls exec, recording completion, and rethrowing exception if
435	<	* encountered. Caller should normally check status before calling.
436	<	*
437	<	* @return true if completed normally
438	<	*/
439	<	private boolean tryExec() {
440	<	try { // try block must contain only call to exec
441	<	if (!exec())
442	<	return false;
443	<	} catch (Throwable rex) {
444	<	setDoneExceptionally(rex);
445	<	rethrowException(rex);
446	<	return false; // not reached
447	<	}
448	<	setNormalCompletion();
449	<	return true;
450	<	}
451	<
452	<	/**
453	<	* Main execution method used by worker threads. Invokes
454	<	* base computation unless already complete.
304	>	* Unless done, calls exec and records status if completed, or
305	>	* waits for completion otherwise.
306	>	* @return status on exit
307		*/
308	<	final void quietlyExec() {
309	<	if (status >= 0) {
308	>	private int doInvoke() {
309	>	int stat;
310	>	if ((stat = status) >= 0) {
311	>	boolean completed;
312		try {
313	<	if (!exec())
460	<	return;
313	>	completed = exec();
314		} catch (Throwable rex) {
315	<	setDoneExceptionally(rex);
463	<	return;
315	>	return setExceptionalCompletion(rex);
316		}
317	<	setNormalCompletion();
466	<	}
467	<	}
468	<
469	<	/**
470	<	* Calls exec(), recording but not rethrowing exception.
471	<	* Caller should normally check status before calling.
472	<	*
473	<	* @return true if completed normally
474	<	*/
475	<	private boolean tryQuietlyInvoke() {
476	<	try {
477	<	if (!exec())
478	<	return false;
479	<	} catch (Throwable rex) {
480	<	setDoneExceptionally(rex);
481	<	return false;
317	>	stat = completed ? setCompletion(NORMAL) : doJoin();
318		}
319	<	setNormalCompletion();
484	<	return true;
319	>	return stat;
320		}
321
322		/**
323	<	* Cancels, ignoring any exceptions it throws.
323	>	* Returns result or throws exception associated with given status.
324	>	* @param s the status
325		*/
326	<	final void cancelIgnoringExceptions() {
327	<	try {
328	<	cancel(false);
329	<	} catch (Throwable ignore) {
330	<	}
495	<	}
496	<
497	<	/**
498	<	* Main implementation of helpJoin
499	<	*/
500	<	private int busyJoin(ForkJoinWorkerThread w) {
501	<	int s;
502	<	ForkJoinTask<?> t;
503	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
504	<	t.quietlyExec();
505	<	return (s >= 0) ? awaitDone(w, false) : s; // block if no work
326	>	private V reportResult(int s) {
327	>	Throwable ex;
328	>	if (s < NORMAL && (ex = getException()) != null)
329	>	UNSAFE.throwException(ex);
330	>	return getRawResult();
331		}
332
333		// public methods
#	Line 511 | Line 336 | public abstract class ForkJoinTask<V> im
336		* Arranges to asynchronously execute this task.  While it is not
337		* necessarily enforced, it is a usage error to fork a task more
338		* than once unless it has completed and been reinitialized.
339	+	* Subsequent modifications to the state of this task or any data
340	+	* it operates on are not necessarily consistently observable by
341	+	* any thread other than the one executing it unless preceded by a
342	+	* call to {@link #join} or related methods, or a call to {@link
343	+	* #isDone} returning {@code true}.
344		*
345		* <p>This method may be invoked only from within {@code
346		* ForkJoinTask} computations (as may be determined using method
#	Line 535 | Line 365 | public abstract class ForkJoinTask<V> im
365		* @return the computed result
366		*/
367		public final V join() {
368	<	ForkJoinWorkerThread w = getWorker();
539	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
540	<	reportException(awaitDone(w, true));
541	<	return getRawResult();
368	>	return reportResult(doJoin());
369		}
370
371		/**
#	Line 549 | Line 376 | public abstract class ForkJoinTask<V> im
376		* @return the computed result
377		*/
378		public final V invoke() {
379	<	if (status >= 0 && tryExec())
553	<	return getRawResult();
554	<	else
555	<	return join();
379	>	return reportResult(doInvoke());
380		}
381
382		/**
#	Line 610 | Line 434 | public abstract class ForkJoinTask<V> im
434		}
435		else if (i != 0)
436		t.fork();
437	<	else {
438	<	t.quietlyInvoke();
615	<	if (ex == null)
616	<	ex = t.getException();
617	<	}
437	>	else if (t.doInvoke() < NORMAL && ex == null)
438	>	ex = t.getException();
439		}
440		for (int i = 1; i <= last; ++i) {
441		ForkJoinTask<?> t = tasks[i];
442		if (t != null) {
443		if (ex != null)
444		t.cancel(false);
445	<	else {
446	<	t.quietlyJoin();
626	<	if (ex == null)
627	<	ex = t.getException();
628	<	}
445	>	else if (t.doJoin() < NORMAL && ex == null)
446	>	ex = t.getException();
447		}
448		}
449		if (ex != null)
450	<	rethrowException(ex);
450	>	UNSAFE.throwException(ex);
451		}
452
453		/**
#	Line 672 | Line 490 | public abstract class ForkJoinTask<V> im
490		}
491		else if (i != 0)
492		t.fork();
493	<	else {
494	<	t.quietlyInvoke();
677	<	if (ex == null)
678	<	ex = t.getException();
679	<	}
493	>	else if (t.doInvoke() < NORMAL && ex == null)
494	>	ex = t.getException();
495		}
496		for (int i = 1; i <= last; ++i) {
497		ForkJoinTask<?> t = ts.get(i);
498		if (t != null) {
499		if (ex != null)
500		t.cancel(false);
501	<	else {
502	<	t.quietlyJoin();
688	<	if (ex == null)
689	<	ex = t.getException();
690	<	}
501	>	else if (t.doJoin() < NORMAL && ex == null)
502	>	ex = t.getException();
503		}
504		}
505		if (ex != null)
506	<	rethrowException(ex);
506	>	UNSAFE.throwException(ex);
507		return tasks;
508		}
509
#	Line 720 | Line 532 | public abstract class ForkJoinTask<V> im
532		* @return {@code true} if this task is now cancelled
533		*/
534		public boolean cancel(boolean mayInterruptIfRunning) {
535	<	setCompletion(CANCELLED);
536	<	return (status & COMPLETION_MASK) == CANCELLED;
535	>	return setCompletion(CANCELLED) == CANCELLED;
536	>	}
537	>
538	>	/**
539	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
540	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
541	>	* exceptions, but if it does anyway, we have no recourse during
542	>	* shutdown, so guard against this case.
543	>	*/
544	>	final void cancelIgnoringExceptions() {
545	>	try {
546	>	cancel(false);
547	>	} catch (Throwable ignore) {
548	>	}
549	>	}
550	>
551	>	/**
552	>	* Cancels ignoring exceptions if worker is terminating
553	>	*/
554	>	final void cancelIfTerminating() {
555	>	Thread t = Thread.currentThread();
556	>	if ((t instanceof ForkJoinWorkerThread) &&
557	>	((ForkJoinWorkerThread) t).isTerminating()) {
558	>	try {
559	>	cancel(false);
560	>	} catch (Throwable ignore) {
561	>	}
562	>	}
563		}
564
565		public final boolean isDone() {
#	Line 729 | Line 567 | public abstract class ForkJoinTask<V> im
567		}
568
569		public final boolean isCancelled() {
570	<	return (status & COMPLETION_MASK) == CANCELLED;
570	>	return status == CANCELLED;
571		}
572
573		/**
#	Line 738 | Line 576 | public abstract class ForkJoinTask<V> im
576		* @return {@code true} if this task threw an exception or was cancelled
577		*/
578		public final boolean isCompletedAbnormally() {
579	<	return (status & COMPLETION_MASK) < NORMAL;
579	>	return status < NORMAL;
580		}
581
582		/**
#	Line 749 | Line 587 | public abstract class ForkJoinTask<V> im
587		* exception and was not cancelled
588		*/
589		public final boolean isCompletedNormally() {
590	<	return (status & COMPLETION_MASK) == NORMAL;
590	>	return status == NORMAL;
591		}
592
593		/**
#	Line 760 | Line 598 | public abstract class ForkJoinTask<V> im
598		* @return the exception, or {@code null} if none
599		*/
600		public final Throwable getException() {
601	<	int s = status & COMPLETION_MASK;
601	>	int s = status;
602		return ((s >= NORMAL)    ? null :
603		(s == CANCELLED) ? new CancellationException() :
604		exceptionMap.get(this));
#	Line 776 | Line 614 | public abstract class ForkJoinTask<V> im
614		* overridable, but overridden versions must invoke {@code super}
615		* implementation to maintain guarantees.
616		*
617	<	* @param ex the exception to throw. If this exception is
618	<	* not a RuntimeException or Error, the actual exception thrown
619	<	* will be a RuntimeException with cause ex.
617	>	* @param ex the exception to throw. If this exception is not a
618	>	* {@code RuntimeException} or {@code Error}, the actual exception
619	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
620		*/
621		public void completeExceptionally(Throwable ex) {
622	<	setDoneExceptionally((ex instanceof RuntimeException) ||
623	<	(ex instanceof Error) ? ex :
624	<	new RuntimeException(ex));
622	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
623	>	(ex instanceof Error) ? ex :
624	>	new RuntimeException(ex));
625		}
626
627		/**
#	Line 802 | Line 640 | public abstract class ForkJoinTask<V> im
640		try {
641		setRawResult(value);
642		} catch (Throwable rex) {
643	<	setDoneExceptionally(rex);
643	>	setExceptionalCompletion(rex);
644		return;
645		}
646	<	setNormalCompletion();
646	>	setCompletion(NORMAL);
647		}
648
649		public final V get() throws InterruptedException, ExecutionException {
650	<	ForkJoinWorkerThread w = getWorker();
651	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
652	<	awaitDone(w, true);
653	<	return reportFutureResult();
650	>	int s = doJoin();
651	>	if (Thread.interrupted())
652	>	throw new InterruptedException();
653	>	if (s < NORMAL) {
654	>	Throwable ex;
655	>	if (s == CANCELLED)
656	>	throw new CancellationException();
657	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
658	>	throw new ExecutionException(ex);
659	>	}
660	>	return getRawResult();
661		}
662
663		public final V get(long timeout, TimeUnit unit)
664		throws InterruptedException, ExecutionException, TimeoutException {
665	<	long nanos = unit.toNanos(timeout);
666	<	ForkJoinWorkerThread w = getWorker();
667	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
668	<	awaitDone(w, nanos);
669	<	return reportTimedFutureResult();
670	<	}
671	<
672	<	/**
673	<	* Possibly executes other tasks until this task {@link #isDone is
674	<	* done}, then returns the result of the computation.  This method
675	<	* may be more efficient than {@code join}, but is only applicable
676	<	* when there are no potential dependencies between continuation
677	<	* of the current task and that of any other task that might be
678	<	* executed while helping. (This usually holds for pure
679	<	* divide-and-conquer tasks).
680	<	*
681	<	* <p>This method may be invoked only from within {@code
682	<	* ForkJoinTask} computations (as may be determined using method
683	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
684	<	* result in exceptions or errors, possibly including {@code
685	<	* ClassCastException}.
686	<	*
687	<	* @return the computed result
688	<	*/
689	<	public final V helpJoin() {
690	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
691	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
692	<	reportException(busyJoin(w));
693	<	return getRawResult();
694	<	}
695	<
696	<	/**
697	<	* Possibly executes other tasks until this task {@link #isDone is
698	<	* done}.  This method may be useful when processing collections
699	<	* of tasks when some have been cancelled or otherwise known to
700	<	* have aborted.
701	<	*
702	<	* <p>This method may be invoked only from within {@code
703	<	* ForkJoinTask} computations (as may be determined using method
704	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
705	<	* result in exceptions or errors, possibly including {@code
706	<	* ClassCastException}.
707	<	*/
708	<	public final void quietlyHelpJoin() {
709	<	if (status >= 0) {
710	<	ForkJoinWorkerThread w =
711	<	(ForkJoinWorkerThread) Thread.currentThread();
712	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
713	<	busyJoin(w);
665	>	Thread t = Thread.currentThread();
666	>	ForkJoinPool pool;
667	>	if (t instanceof ForkJoinWorkerThread) {
668	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
669	>	if (status >= 0 && w.unpushTask(this))
670	>	tryExec();
671	>	pool = w.pool;
672	>	}
673	>	else
674	>	pool = null;
675	>	/*
676	>	* Timed wait loop intermixes cases for FJ (pool != null) and
677	>	* non FJ threads. For FJ, decrement pool count but don't try
678	>	* for replacement; increment count on completion. For non-FJ,
679	>	* deal with interrupts. This is messy, but a little less so
680	>	* than is splitting the FJ and nonFJ cases.
681	>	*/
682	>	boolean interrupted = false;
683	>	boolean dec = false; // true if pool count decremented
684	>	for (;;) {
685	>	if (Thread.interrupted() && pool == null) {
686	>	interrupted = true;
687	>	break;
688	>	}
689	>	int s = status;
690	>	if (s < 0)
691	>	break;
692	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
693	>	long startTime = System.nanoTime();
694	>	long nanos = unit.toNanos(timeout);
695	>	long nt; // wait time
696	>	while (status >= 0 &&
697	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
698	>	if (pool != null && !dec)
699	>	dec = pool.tryDecrementRunningCount();
700	>	else {
701	>	long ms = nt / 1000000;
702	>	int ns = (int) (nt % 1000000);
703	>	try {
704	>	synchronized(this) {
705	>	if (status >= 0)
706	>	wait(ms, ns);
707	>	}
708	>	} catch (InterruptedException ie) {
709	>	if (pool != null)
710	>	cancelIfTerminating();
711	>	else {
712	>	interrupted = true;
713	>	break;
714	>	}
715	>	}
716	>	}
717	>	}
718	>	break;
719	>	}
720		}
721	+	if (pool != null && dec)
722	+	pool.incrementRunningCount();
723	+	if (interrupted)
724	+	throw new InterruptedException();
725	+	int es = status;
726	+	if (es != NORMAL) {
727	+	Throwable ex;
728	+	if (es == CANCELLED)
729	+	throw new CancellationException();
730	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
731	+	throw new ExecutionException(ex);
732	+	throw new TimeoutException();
733	+	}
734	+	return getRawResult();
735		}
736
737		/**
#	Line 876 | Line 741 | public abstract class ForkJoinTask<V> im
741		* known to have aborted.
742		*/
743		public final void quietlyJoin() {
744	<	if (status >= 0) {
880	<	ForkJoinWorkerThread w = getWorker();
881	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
882	<	awaitDone(w, true);
883	<	}
744	>	doJoin();
745		}
746
747		/**
#	Line 891 | Line 752 | public abstract class ForkJoinTask<V> im
752		* known to have aborted.
753		*/
754		public final void quietlyInvoke() {
755	<	if (status >= 0 && !tryQuietlyInvoke())
895	<	quietlyJoin();
755	>	doInvoke();
756		}
757
758		/**
#	Line 924 | Line 784 | public abstract class ForkJoinTask<V> im
784		* pre-constructed trees of subtasks in loops.
785		*/
786		public void reinitialize() {
787	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
787	>	if (status == EXCEPTIONAL)
788		exceptionMap.remove(this);
789		status = 0;
790		}
#	Line 1214 | Line 1074 | public abstract class ForkJoinTask<V> im
1074		private static final long serialVersionUID = -7721805057305804111L;
1075
1076		/**
1077	<	* Save the state to a stream.
1077	>	* Saves the state to a stream.
1078		*
1079		* @serialData the current run status and the exception thrown
1080		* during execution, or {@code null} if none
#	Line 1227 | Line 1087 | public abstract class ForkJoinTask<V> im
1087		}
1088
1089		/**
1090	<	* Reconstitute the instance from a stream.
1090	>	* Reconstitutes the instance from a stream.
1091		*
1092		* @param s the stream
1093		*/
1094		private void readObject(java.io.ObjectInputStream s)
1095		throws java.io.IOException, ClassNotFoundException {
1096		s.defaultReadObject();
1237	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1238	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1097		Object ex = s.readObject();
1098		if (ex != null)
1099	<	setDoneExceptionally((Throwable) ex);
1099	>	setExceptionalCompletion((Throwable) ex);
1100		}
1101
1102		// Unsafe mechanics

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