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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.38 by dl, Tue Aug 4 22:47:08 2009 UTC vs.
Revision 1.51 by dl, Fri Jul 23 16:49:11 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 80 | Line 77 | import java.util.WeakHashMap;
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);
83	–	* {@link #isCancelled} is true if completion was due to cancellation;
80		* {@link #isCompletedNormally} is true if a task completed without
81	<	* cancellation or encountering an exception; {@link
82	<	* #isCompletedExceptionally} is true if if the task encountered an
83	<	* exception (in which case {@link #getException} returns the
84	<	* exception); {@link #isCancelled} is true if the task was cancelled
85	<	* (in which case {@link #getException} returns a {@link
86	<	* java.util.concurrent.CancellationException}); and {@link
87	<	* #isCompletedAbnormally} is true if a task was either cancelled or
92	<	* encountered an exception.
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
#	Line 127 | 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
132	<	* {@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 141 | 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;
168	<	static final int SIGNAL_MASK          = 0x0000ffff;
169	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
170	<	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 181 | Line 184 | public abstract class ForkJoinTask<V> im
184		Collections.synchronizedMap
185		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
186
187	<	// within-package utilities
185	<
186	<	/**
187	<	* Gets current worker thread, or null if not a worker thread.
188	<	*/
189	<	static ForkJoinWorkerThread getWorker() {
190	<	Thread t = Thread.currentThread();
191	<	return ((t instanceof ForkJoinWorkerThread) ?
192	<	(ForkJoinWorkerThread) t : null);
193	<	}
194	<
195	<	final boolean casStatus(int cmp, int val) {
196	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
197	<	}
198	<
199	<	/**
200	<	* Workaround for not being able to rethrow unchecked exceptions.
201	<	*/
202	<	static void rethrowException(Throwable ex) {
203	<	if (ex != null)
204	<	UNSAFE.throwException(ex);
205	<	}
206	<
207	<	// Setting completion status
187	>	// Maintaining completion status
188
189		/**
190	<	* 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) {
221	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
222	<	pool.updateRunningCount(s);
223	<	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
227	<	externallySetCompletion(completion);
228	<	}
229	<
230	<	/**
231	<	* Version of setCompletion for non-FJ threads.  Leaves signal
232	<	* bits for unblocked threads to adjust, and always notifies.
233	<	*/
234	<	private void externallySetCompletion(int completion) {
235	<	int s;
236	<	do {} while ((s = status) >= 0 &&
237	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
238	<	synchronized (this) { notifyAll(); }
239	<	}
240	<
241	<	/**
242	<	* Sets status to indicate normal completion.
243	<	*/
244	<	final void setNormalCompletion() {
245	<	// Try typical fast case -- single CAS, no signal, not already done.
246	<	// Manually expand casStatus to improve chances of inlining it
247	<	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
248	<	setCompletion(NORMAL);
205	>	return s;
206		}
207
251	–	// internal waiting and notification
252	–
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
259	<	try {
260	<	while (status >= 0)
261	<	synchronized (this) { if (status >= 0) wait(); }
262	<	} catch (InterruptedException ie) {
263	<	onInterruptedWait();
264	<	}
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)
276	<	break;
277	<	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();
229	>	cancelIfTerminating();
230		}
231		}
232		}
233
285	–	// Awaiting completion
286	–
234		/**
235	<	* Sets status to indicate there is joiner, then waits for join,
236	<	* surrounded with pool notifications.
290	<	*
291	<	* @return status upon exit
235	>	* Blocks a non-worker-thread until completion.
236	>	* @return status on exit
237		*/
238	<	private int awaitDone(ForkJoinWorkerThread w,
294	<	boolean maintainParallelism) {
295	<	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	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
243	<	doAwaitDone();
244	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
245	<	adjustPoolCountsOnUnblock(pool);
246	<	break;
247	<	}
248	<	}
249	<	return s;
250	<	}
251	<
252	<	/**
253	<	* Timed version of awaitDone
311	<	*
312	<	* @return status upon exit
313	<	*/
314	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
315	<	ForkJoinPool pool = (w == null) ? null : w.pool;
316	<	int s;
317	<	while ((s = status) >= 0) {
318	<	if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) {
319	<	long startTime = System.nanoTime();
320	<	if (pool == null || !pool.preJoin(this, false))
321	<	doAwaitDone(startTime, nanos);
322	<	if ((s = status) >= 0) {
323	<	adjustPoolCountsOnCancelledWait(pool);
324	<	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		}
326	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
327	–	adjustPoolCountsOnUnblock(pool);
328	–	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.
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 void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
282	<	if (pool != null) {
283	<	int s;
284	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
285	<	if (casStatus(s, s - 1)) {
286	<	pool.updateRunningCount(1);
287	<	break;
281	>	private int doJoin() {
282	>	int stat;
283	>	if ((stat = status) < 0)
284	>	return stat;
285	>	Thread t = Thread.currentThread();
286	>	ForkJoinWorkerThread w;
287	>	if (t instanceof ForkJoinWorkerThread) {
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() {
364	<	ForkJoinWorkerThread w = getWorker();
365	<	if (w == null)
366	<	Thread.currentThread().interrupt(); // re-interrupt
367	<	else if (w.isTerminating())
368	<	cancelIgnoringExceptions();
369	<	// else if FJworker, ignore interrupt
370	<	}
371	<
372	<	// Recording and reporting exceptions
373	<
374	<	private void setDoneExceptionally(Throwable rex) {
375	<	exceptionMap.put(this, rex);
376	<	setCompletion(EXCEPTIONAL);
377	<	}
378	<
379	<	/**
380	<	* Throws the exception associated with status s.
381	<	*
382	<	* @throws the exception
383	<	*/
384	<	private void reportException(int s) {
385	<	if ((s &= COMPLETION_MASK) < NORMAL) {
386	<	if (s == CANCELLED)
387	<	throw new CancellationException();
388	<	else
389	<	rethrowException(exceptionMap.get(this));
390	<	}
391	<	}
392	<
393	<	/**
394	<	* Returns result or throws exception using j.u.c.Future conventions.
395	<	* Only call when {@code isDone} known to be true or thread known
396	<	* to be interrupted.
397	<	*/
398	<	private V reportFutureResult()
399	<	throws InterruptedException, ExecutionException {
400	<	if (Thread.interrupted())
401	<	throw new InterruptedException();
402	<	int s = status & COMPLETION_MASK;
403	<	if (s < NORMAL) {
404	<	Throwable ex;
405	<	if (s == CANCELLED)
406	<	throw new CancellationException();
407	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
408	<	throw new ExecutionException(ex);
409	<	}
410	<	return getRawResult();
411	<	}
412	<
413	<	/**
414	<	* Returns result or throws exception using j.u.c.Future conventions
415	<	* with timeouts.
304	>	* Unless done, calls exec and records status if completed, or
305	>	* waits for completion otherwise.
306	>	* @return status on exit
307		*/
308	<	private V reportTimedFutureResult()
309	<	throws InterruptedException, ExecutionException, TimeoutException {
310	<	if (Thread.interrupted())
311	<	throw new InterruptedException();
421	<	Throwable ex;
422	<	int s = status & COMPLETION_MASK;
423	<	if (s == NORMAL)
424	<	return getRawResult();
425	<	else if (s == CANCELLED)
426	<	throw new CancellationException();
427	<	else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
428	<	throw new ExecutionException(ex);
429	<	else
430	<	throw new TimeoutException();
431	<	}
432	<
433	<	// internal execution methods
434	<
435	<	/**
436	<	* Calls exec, recording completion, and rethrowing exception if
437	<	* encountered. Caller should normally check status before calling.
438	<	*
439	<	* @return true if completed normally
440	<	*/
441	<	private boolean tryExec() {
442	<	try { // try block must contain only call to exec
443	<	if (!exec())
444	<	return false;
445	<	} catch (Throwable rex) {
446	<	setDoneExceptionally(rex);
447	<	rethrowException(rex);
448	<	return false; // not reached
449	<	}
450	<	setNormalCompletion();
451	<	return true;
452	<	}
453	<
454	<	/**
455	<	* Main execution method used by worker threads. Invokes
456	<	* base computation unless already complete.
457	<	*/
458	<	final void quietlyExec() {
459	<	if (status >= 0) {
308	>	private int doInvoke() {
309	>	int stat;
310	>	if ((stat = status) >= 0) {
311	>	boolean completed;
312		try {
313	<	if (!exec())
462	<	return;
313	>	completed = exec();
314		} catch (Throwable rex) {
315	<	setDoneExceptionally(rex);
465	<	return;
315	>	return setExceptionalCompletion(rex);
316		}
317	<	setNormalCompletion();
317	>	stat = completed ? setCompletion(NORMAL) : doJoin();
318		}
319	+	return stat;
320		}
321
322		/**
323	<	* Calls exec(), recording but not rethrowing exception.
324	<	* Caller should normally check status before calling.
474	<	*
475	<	* @return true if completed normally
323	>	* Returns result or throws exception associated with given status.
324	>	* @param s the status
325		*/
326	<	private boolean tryQuietlyInvoke() {
327	<	try {
328	<	if (!exec())
329	<	return false;
330	<	} catch (Throwable rex) {
482	<	setDoneExceptionally(rex);
483	<	return false;
484	<	}
485	<	setNormalCompletion();
486	<	return true;
487	<	}
488	<
489	<	/**
490	<	* Cancels, ignoring any exceptions it throws.
491	<	*/
492	<	final void cancelIgnoringExceptions() {
493	<	try {
494	<	cancel(false);
495	<	} catch (Throwable ignore) {
496	<	}
497	<	}
498	<
499	<	/**
500	<	* Main implementation of helpJoin
501	<	*/
502	<	private int busyJoin(ForkJoinWorkerThread w) {
503	<	int s;
504	<	ForkJoinTask<?> t;
505	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
506	<	t.quietlyExec();
507	<	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 513 | 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 529 | Line 357 | public abstract class ForkJoinTask<V> im
357		}
358
359		/**
360	<	* Returns the result of the computation when it is ready.
360	>	* Returns the result of the computation when it {@link #isDone is done}.
361		* This method differs from {@link #get()} in that
362		* abnormal completion results in {@code RuntimeException} or
363		* {@code Error}, not {@code ExecutionException}.
#	Line 537 | Line 365 | public abstract class ForkJoinTask<V> im
365		* @return the computed result
366		*/
367		public final V join() {
368	<	ForkJoinWorkerThread w = getWorker();
541	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
542	<	reportException(awaitDone(w, true));
543	<	return getRawResult();
368	>	return reportResult(doJoin());
369		}
370
371		/**
#	Line 551 | Line 376 | public abstract class ForkJoinTask<V> im
376		* @return the computed result
377		*/
378		public final V invoke() {
379	<	if (status >= 0 && tryExec())
555	<	return getRawResult();
556	<	else
557	<	return join();
379	>	return reportResult(doInvoke());
380		}
381
382		/**
383		* Forks the given tasks, returning when {@code isDone} holds for
384		* each task or an (unchecked) exception is encountered, in which
385	<	* case the exception is rethrown.  If more than one task
386	<	* encounters an exception, then this method throws any one of
387	<	* these exceptions.  The individual status of each task may be
385	>	* case the exception is rethrown.  If either task encounters an
386	>	* exception, the other one may be, but is not guaranteed to be,
387	>	* cancelled.  If both tasks throw an exception, then this method
388	>	* throws one of them.  The individual status of each task may be
389		* checked using {@link #getException()} and related methods.
390		*
391		* <p>This method may be invoked only from within {@code
#	Line 611 | Line 434 | public abstract class ForkJoinTask<V> im
434		}
435		else if (i != 0)
436		t.fork();
437	<	else {
438	<	t.quietlyInvoke();
616	<	if (ex == null)
617	<	ex = t.getException();
618	<	}
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();
627	<	if (ex == null)
628	<	ex = t.getException();
629	<	}
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 673 | Line 490 | public abstract class ForkJoinTask<V> im
490		}
491		else if (i != 0)
492		t.fork();
493	<	else {
494	<	t.quietlyInvoke();
678	<	if (ex == null)
679	<	ex = t.getException();
680	<	}
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();
689	<	if (ex == null)
690	<	ex = t.getException();
691	<	}
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 721 | 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);
725	<	return (status & COMPLETION_MASK) == CANCELLED;
535	>	return setCompletion(CANCELLED) == CANCELLED;
536		}
537
538		/**
539	<	* Returns {@code true} if the computation performed by this task
540	<	* has completed (or has been cancelled).
731	<	*
732	<	* @return {@code true} if this computation has completed
539	>	* Cancels, ignoring any exceptions it throws. Used during worker
540	>	* and pool shutdown.
541		*/
542	<	public final boolean isDone() {
543	<	return status < 0;
542	>	final void cancelIgnoringExceptions() {
543	>	try {
544	>	cancel(false);
545	>	} catch (Throwable ignore) {
546	>	}
547		}
548
549		/**
550	<	* Returns {@code true} if this task was cancelled.
740	<	*
741	<	* @return {@code true} if this task was cancelled
550	>	* Cancels ignoring exceptions if worker is terminating
551		*/
552	+	final void cancelIfTerminating() {
553	+	Thread t = Thread.currentThread();
554	+	if ((t instanceof ForkJoinWorkerThread) &&
555	+	((ForkJoinWorkerThread) t).isTerminating()) {
556	+	try {
557	+	cancel(false);
558	+	} catch (Throwable ignore) {
559	+	}
560	+	}
561	+	}
562	+
563	+	public final boolean isDone() {
564	+	return status < 0;
565	+	}
566	+
567		public final boolean isCancelled() {
568	<	return (status & COMPLETION_MASK) == CANCELLED;
568	>	return status == CANCELLED;
569		}
570
571		/**
#	Line 750 | Line 574 | public abstract class ForkJoinTask<V> im
574		* @return {@code true} if this task threw an exception or was cancelled
575		*/
576		public final boolean isCompletedAbnormally() {
577	<	return (status & COMPLETION_MASK) < NORMAL;
577	>	return status < NORMAL;
578		}
579
580		/**
#	Line 761 | Line 585 | public abstract class ForkJoinTask<V> im
585		* exception and was not cancelled
586		*/
587		public final boolean isCompletedNormally() {
588	<	return (status & COMPLETION_MASK) == NORMAL;
765	<	}
766	<
767	<	/**
768	<	* Returns {@code true} if this task threw an exception.
769	<	*
770	<	* @return {@code true} if this task threw an exception
771	<	*/
772	<	public final boolean isCompletedExceptionally() {
773	<	return (status & COMPLETION_MASK) == EXCEPTIONAL;
588	>	return status == NORMAL;
589		}
590
591		/**
#	Line 781 | Line 596 | public abstract class ForkJoinTask<V> im
596		* @return the exception, or {@code null} if none
597		*/
598		public final Throwable getException() {
599	<	int s = status & COMPLETION_MASK;
599	>	int s = status;
600		return ((s >= NORMAL)    ? null :
601		(s == CANCELLED) ? new CancellationException() :
602		exceptionMap.get(this));
#	Line 797 | Line 612 | public abstract class ForkJoinTask<V> im
612		* overridable, but overridden versions must invoke {@code super}
613		* implementation to maintain guarantees.
614		*
615	<	* @param ex the exception to throw. If this exception is
616	<	* not a RuntimeException or Error, the actual exception thrown
617	<	* will be a RuntimeException with cause ex.
615	>	* @param ex the exception to throw. If this exception is not a
616	>	* {@code RuntimeException} or {@code Error}, the actual exception
617	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
618		*/
619		public void completeExceptionally(Throwable ex) {
620	<	setDoneExceptionally((ex instanceof RuntimeException) ||
621	<	(ex instanceof Error) ? ex :
622	<	new RuntimeException(ex));
620	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
621	>	(ex instanceof Error) ? ex :
622	>	new RuntimeException(ex));
623		}
624
625		/**
#	Line 823 | Line 638 | public abstract class ForkJoinTask<V> im
638		try {
639		setRawResult(value);
640		} catch (Throwable rex) {
641	<	setDoneExceptionally(rex);
641	>	setExceptionalCompletion(rex);
642		return;
643		}
644	<	setNormalCompletion();
644	>	setCompletion(NORMAL);
645		}
646
647		public final V get() throws InterruptedException, ExecutionException {
648	<	ForkJoinWorkerThread w = getWorker();
649	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
650	<	awaitDone(w, true);
651	<	return reportFutureResult();
648	>	int s = doJoin();
649	>	if (Thread.interrupted())
650	>	throw new InterruptedException();
651	>	if (s < NORMAL) {
652	>	Throwable ex;
653	>	if (s == CANCELLED)
654	>	throw new CancellationException();
655	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
656	>	throw new ExecutionException(ex);
657	>	}
658	>	return getRawResult();
659		}
660
661		public final V get(long timeout, TimeUnit unit)
662		throws InterruptedException, ExecutionException, TimeoutException {
663	<	long nanos = unit.toNanos(timeout);
664	<	ForkJoinWorkerThread w = getWorker();
665	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
666	<	awaitDone(w, nanos);
667	<	return reportTimedFutureResult();
668	<	}
669	<
848	<	/**
849	<	* Possibly executes other tasks until this task is ready, then
850	<	* returns the result of the computation.  This method may be more
851	<	* efficient than {@code join}, but is only applicable when
852	<	* there are no potential dependencies between continuation of the
853	<	* current task and that of any other task that might be executed
854	<	* while helping. (This usually holds for pure divide-and-conquer
855	<	* tasks).
856	<	*
857	<	* <p>This method may be invoked only from within {@code
858	<	* ForkJoinTask} computations (as may be determined using method
859	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
860	<	* result in exceptions or errors, possibly including {@code
861	<	* ClassCastException}.
862	<	*
863	<	* @return the computed result
864	<	*/
865	<	public final V helpJoin() {
866	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
867	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
868	<	reportException(busyJoin(w));
869	<	return getRawResult();
870	<	}
871	<
872	<	/**
873	<	* Possibly executes other tasks until this task is ready.  This
874	<	* method may be useful when processing collections of tasks when
875	<	* some have been cancelled or otherwise known to have aborted.
876	<	*
877	<	* <p>This method may be invoked only from within {@code
878	<	* ForkJoinTask} computations (as may be determined using method
879	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
880	<	* result in exceptions or errors, possibly including {@code
881	<	* ClassCastException}.
882	<	*/
883	<	public final void quietlyHelpJoin() {
884	<	if (status >= 0) {
885	<	ForkJoinWorkerThread w =
886	<	(ForkJoinWorkerThread) Thread.currentThread();
887	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
888	<	busyJoin(w);
663	>	Thread t = Thread.currentThread();
664	>	ForkJoinPool pool;
665	>	if (t instanceof ForkJoinWorkerThread) {
666	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
667	>	if (status >= 0 && w.unpushTask(this))
668	>	tryExec();
669	>	pool = w.pool;
670		}
671	+	else
672	+	pool = null;
673	+	/*
674	+	* Timed wait loop intermixes cases for fj (pool != null) and
675	+	* non FJ threads. For FJ, decrement pool count but don't try
676	+	* for replacement; increment count on completion. For non-FJ,
677	+	* deal with interrupts. This is messy, but a little less so
678	+	* than is splitting the FJ and nonFJ cases.
679	+	*/
680	+	boolean interrupted = false;
681	+	boolean dec = false; // true if pool count decremented
682	+	for (;;) {
683	+	if (Thread.interrupted() && pool == null) {
684	+	interrupted = true;
685	+	break;
686	+	}
687	+	int s = status;
688	+	if (s < 0)
689	+	break;
690	+	if (UNSAFE.compareAndSwapInt(this, statusOffset,
691	+	s, s | SIGNAL)) {
692	+	long startTime = System.nanoTime();
693	+	long nanos = unit.toNanos(timeout);
694	+	long nt; // wait time
695	+	while (status >= 0 &&
696	+	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
697	+	if (pool != null && !dec)
698	+	dec = pool.tryDecrementRunningCount();
699	+	else {
700	+	long ms = nt / 1000000;
701	+	int ns = (int) (nt % 1000000);
702	+	try {
703	+	synchronized(this) {
704	+	if (status >= 0)
705	+	wait(ms, ns);
706	+	}
707	+	} catch (InterruptedException ie) {
708	+	if (pool != null)
709	+	cancelIfTerminating();
710	+	else {
711	+	interrupted = true;
712	+	break;
713	+	}
714	+	}
715	+	}
716	+	}
717	+	break;
718	+	}
719	+	}
720	+	if (pool != null && dec)
721	+	pool.incrementRunningCount();
722	+	if (interrupted)
723	+	throw new InterruptedException();
724	+	int es = status;
725	+	if (es != NORMAL) {
726	+	Throwable ex;
727	+	if (es == CANCELLED)
728	+	throw new CancellationException();
729	+	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
730	+	throw new ExecutionException(ex);
731	+	throw new TimeoutException();
732	+	}
733	+	return getRawResult();
734		}
735
736		/**
#	Line 896 | Line 740 | public abstract class ForkJoinTask<V> im
740		* known to have aborted.
741		*/
742		public final void quietlyJoin() {
743	<	if (status >= 0) {
900	<	ForkJoinWorkerThread w = getWorker();
901	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
902	<	awaitDone(w, true);
903	<	}
743	>	doJoin();
744		}
745
746		/**
#	Line 911 | Line 751 | public abstract class ForkJoinTask<V> im
751		* known to have aborted.
752		*/
753		public final void quietlyInvoke() {
754	<	if (status >= 0 && !tryQuietlyInvoke())
915	<	quietlyJoin();
754	>	doInvoke();
755		}
756
757		/**
#	Line 944 | Line 783 | public abstract class ForkJoinTask<V> im
783		* pre-constructed trees of subtasks in loops.
784		*/
785		public void reinitialize() {
786	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
786	>	if (status == EXCEPTIONAL)
787		exceptionMap.remove(this);
788		status = 0;
789		}
#	Line 1234 | Line 1073 | public abstract class ForkJoinTask<V> im
1073		private static final long serialVersionUID = -7721805057305804111L;
1074
1075		/**
1076	<	* Save the state to a stream.
1076	>	* Saves the state to a stream.
1077		*
1078		* @serialData the current run status and the exception thrown
1079		* during execution, or {@code null} if none
#	Line 1247 | Line 1086 | public abstract class ForkJoinTask<V> im
1086		}
1087
1088		/**
1089	<	* Reconstitute the instance from a stream.
1089	>	* Reconstitutes the instance from a stream.
1090		*
1091		* @param s the stream
1092		*/
1093		private void readObject(java.io.ObjectInputStream s)
1094		throws java.io.IOException, ClassNotFoundException {
1095		s.defaultReadObject();
1257	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1258	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1096		Object ex = s.readObject();
1097		if (ex != null)
1098	<	setDoneExceptionally((Throwable) ex);
1098	>	setExceptionalCompletion((Throwable) ex);
1099		}
1100
1101		// Unsafe mechanics

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