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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.48 by dl, Thu May 27 16:46:48 2010 UTC vs.
Revision 1.77 by jsr166, Tue Mar 15 19:47:02 2011 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Doug Lea with assistance from members of JCP JSR-166
3		* Expert Group and released to the public domain, as explained at
4	<	* http://creativecommons.org/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6
7		package jsr166y;
8
9	–	import java.util.concurrent.*;
10	–
9		import java.io.Serializable;
10		import java.util.Collection;
11		import java.util.Collections;
12		import java.util.List;
13		import java.util.RandomAccess;
14		import java.util.Map;
15	<	import java.util.WeakHashMap;
15	>	import java.lang.ref.WeakReference;
16	>	import java.lang.ref.ReferenceQueue;
17	>	import java.util.concurrent.Callable;
18	>	import java.util.concurrent.CancellationException;
19	>	import java.util.concurrent.ExecutionException;
20	>	import java.util.concurrent.Executor;
21	>	import java.util.concurrent.ExecutorService;
22	>	import java.util.concurrent.Future;
23	>	import java.util.concurrent.RejectedExecutionException;
24	>	import java.util.concurrent.RunnableFuture;
25	>	import java.util.concurrent.TimeUnit;
26	>	import java.util.concurrent.TimeoutException;
27	>	import java.util.concurrent.locks.ReentrantLock;
28	>	import java.lang.reflect.Constructor;
29
30		/**
31		* Abstract base class for tasks that run within a {@link ForkJoinPool}.
#	Line 28 | Line 39 | import java.util.WeakHashMap;
39		* start other subtasks.  As indicated by the name of this class,
40		* many programs using {@code ForkJoinTask} employ only methods
41		* {@link #fork} and {@link #join}, or derivatives such as {@link
42	<	* #invokeAll}.  However, this class also provides a number of other
43	<	* methods that can come into play in advanced usages, as well as
44	<	* extension mechanics that allow support of new forms of fork/join
45	<	* processing.
42	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
43	>	* provides a number of other methods that can come into play in
44	>	* advanced usages, as well as extension mechanics that allow
45	>	* support of new forms of fork/join processing.
46		*
47		* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
48		* The efficiency of {@code ForkJoinTask}s stems from a set of
#	Line 58 | Line 69 | import java.util.WeakHashMap;
69		* rethrown to callers attempting to join them. These exceptions may
70		* additionally include {@link RejectedExecutionException} stemming
71		* from internal resource exhaustion, such as failure to allocate
72	<	* internal task queues.
72	>	* internal task queues. Rethrown exceptions behave in the same way as
73	>	* regular exceptions, but, when possible, contain stack traces (as
74	>	* displayed for example using {@code ex.printStackTrace()}) of both
75	>	* the thread that initiated the computation as well as the thread
76	>	* actually encountering the exception; minimally only the latter.
77		*
78		* <p>The primary method for awaiting completion and extracting
79		* results of a task is {@link #join}, but there are several variants:
80		* The {@link Future#get} methods support interruptible and/or timed
81		* waits for completion and report results using {@code Future}
82	<	* 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
82	>	* conventions. Method {@link #invoke} is semantically
83		* equivalent to {@code fork(); join()} but always attempts to begin
84		* execution in the current thread. The "<em>quiet</em>" forms of
85		* these methods do not extract results or report exceptions. These
#	Line 103 | Line 115 | import java.util.WeakHashMap;
115		* ForkJoinTasks (as may be determined using method {@link
116		* #inForkJoinPool}).  Attempts to invoke them in other contexts
117		* result in exceptions or errors, possibly including
118	<	* ClassCastException.
118	>	* {@code ClassCastException}.
119	>	*
120	>	* <p>Method {@link #join} and its variants are appropriate for use
121	>	* only when completion dependencies are acyclic; that is, the
122	>	* parallel computation can be described as a directed acyclic graph
123	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
124	>	* tasks cyclically wait for each other.  However, this framework
125	>	* supports other methods and techniques (for example the use of
126	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
127	>	* may be of use in constructing custom subclasses for problems that
128	>	* are not statically structured as DAGs.
129		*
130		* <p>Most base support methods are {@code final}, to prevent
131		* overriding of implementations that are intrinsically tied to the
#	Line 119 | Line 141 | import java.util.WeakHashMap;
141		* computation. Large tasks should be split into smaller subtasks,
142		* usually via recursive decomposition. As a very rough rule of thumb,
143		* a task should perform more than 100 and less than 10000 basic
144	<	* computational steps. If tasks are too big, then parallelism cannot
145	<	* improve throughput. If too small, then memory and internal task
146	<	* maintenance overhead may overwhelm processing.
144	>	* computational steps, and should avoid indefinite looping. If tasks
145	>	* are too big, then parallelism cannot improve throughput. If too
146	>	* small, then memory and internal task maintenance overhead may
147	>	* overwhelm processing.
148		*
149		* <p>This class provides {@code adapt} methods for {@link Runnable}
150		* and {@link Callable}, that may be of use when mixing execution of
151	<	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks
152	<	* are of this form, consider using a pool in
130	<	* {@linkplain ForkJoinPool#setAsyncMode async mode}.
151	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
152	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
153		*
154		* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
155		* used in extensions such as remote execution frameworks. It is
#	Line 151 | Line 173 | public abstract class ForkJoinTask<V> im
173		* in a way that flows well in javadocs.
174		*/
175
176	<	/**
177	<	* Run control status bits packed into a single int to minimize
178	<	* footprint and to ensure atomicity (via CAS).  Status is
179	<	* initially zero, and takes on nonnegative values until
180	<	* completed, upon which status holds COMPLETED. CANCELLED, or
181	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
182	<	* blocking waits by other threads have the SIGNAL bit set.
183	<	*
184	<	* Completion of a stolen task with SIGNAL set awakens any waiters
163	<	* via notifyAll. Even though suboptimal for some purposes, we use
176	>	/*
177	>	* The status field holds run control status bits packed into a
178	>	* single int to minimize footprint and to ensure atomicity (via
179	>	* CAS).  Status is initially zero, and takes on nonnegative
180	>	* values until completed, upon which status holds value
181	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
182	>	* waits by other threads have the SIGNAL bit set.  Completion of
183	>	* a stolen task with SIGNAL set awakens any waiters via
184	>	* notifyAll. Even though suboptimal for some purposes, we use
185		* basic builtin wait/notify to take advantage of "monitor
186		* inflation" in JVMs that we would otherwise need to emulate to
187		* avoid adding further per-task bookkeeping overhead.  We want
188		* these monitors to be "fat", i.e., not use biasing or thin-lock
189		* techniques, so use some odd coding idioms that tend to avoid
190		* them.
170	–	*
171	–	* Note that bits 1-28 are currently unused. Also value
172	–	* 0x80000000 is available as spare completion value.
191		*/
174	–	volatile int status; // accessed directly by pool and workers
192
193	<	private static final int COMPLETION_MASK      = 0xe0000000;
194	<	private static final int NORMAL               = 0xe0000000; // == mask
195	<	private static final int CANCELLED            = 0xc0000000;
196	<	private static final int EXCEPTIONAL          = 0xa0000000;
197	<	private static final int SIGNAL               = 0x00000001;
198	<
182	<	/**
183	<	* Table of exceptions thrown by tasks, to enable reporting by
184	<	* callers. Because exceptions are rare, we don't directly keep
185	<	* them with task objects, but instead use a weak ref table.  Note
186	<	* that cancellation exceptions don't appear in the table, but are
187	<	* instead recorded as status values.
188	<	* TODO: Use ConcurrentReferenceHashMap
189	<	*/
190	<	static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
191	<	Collections.synchronizedMap
192	<	(new WeakHashMap<ForkJoinTask<?>, Throwable>());
193	<
194	<	// Maintaining completion status
193	>	/** The run status of this task */
194	>	volatile int status; // accessed directly by pool and workers
195	>	private static final int NORMAL      = -1;
196	>	private static final int CANCELLED   = -2;
197	>	private static final int EXCEPTIONAL = -3;
198	>	private static final int SIGNAL      =  1;
199
200		/**
201		* Marks completion and wakes up threads waiting to join this task,
202		* also clearing signal request bits.
203		*
204		* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
205	<	* @return status on exit
205	>	* @return completion status on exit
206		*/
207		private int setCompletion(int completion) {
208	<	int s;
209	<	while ((s = status) >= 0) {
208	>	for (int s;;) {
209	>	if ((s = status) < 0)
210	>	return s;
211		if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
212	<	if ((s & SIGNAL) != 0)
212	>	if (s != 0)
213		synchronized (this) { notifyAll(); }
214		return completion;
215		}
216		}
212	–	return s;
217		}
218
219		/**
220	<	* Record exception and set exceptional completion
221	<	* @return status on exit
220	>	* Tries to block a worker thread until completed or timed out.
221	>	* Uses Object.wait time argument conventions.
222	>	* May fail on contention or interrupt.
223	>	*
224	>	* @param millis if > 0, wait time.
225		*/
226	<	private int setExceptionalCompletion(Throwable rex) {
227	<	exceptionMap.put(this, rex);
228	<	return setCompletion(EXCEPTIONAL);
226	>	final void tryAwaitDone(long millis) {
227	>	int s;
228	>	try {
229	>	if (((s = status) > 0 ||
230	>	(s == 0 &&
231	>	UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) &&
232	>	status > 0) {
233	>	synchronized (this) {
234	>	if (status > 0)
235	>	wait(millis);
236	>	}
237	>	}
238	>	} catch (InterruptedException ie) {
239	>	// caller must check termination
240	>	}
241		}
242
243		/**
244	<	* Blocks a worker thread until completion. Called only by pool.
244	>	* Blocks a non-worker-thread until completion.
245	>	* @return status upon completion
246		*/
247	<	final void internalAwaitDone() {
247	>	private int externalAwaitDone() {
248		int s;
249	<	while ((s = status) >= 0) {
250	<	synchronized(this) {
251	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){
252	<	do {
249	>	if ((s = status) >= 0) {
250	>	boolean interrupted = false;
251	>	synchronized (this) {
252	>	while ((s = status) >= 0) {
253	>	if (s == 0)
254	>	UNSAFE.compareAndSwapInt(this, statusOffset,
255	>	0, SIGNAL);
256	>	else {
257		try {
258		wait();
259		} catch (InterruptedException ie) {
260	<	cancelIfTerminating();
260	>	interrupted = true;
261		}
262	<	} while (status >= 0);
239	<	break;
262	>	}
263		}
264		}
265	+	if (interrupted)
266	+	Thread.currentThread().interrupt();
267		}
268	+	return s;
269		}
270
271		/**
272	<	* Blocks a non-worker-thread until completion.
247	<	* @return status on exit
272	>	* Blocks a non-worker-thread until completion or interruption or timeout.
273		*/
274	<	private int externalAwaitDone() {
274	>	private int externalInterruptibleAwaitDone(long millis)
275	>	throws InterruptedException {
276		int s;
277	<	while ((s = status) >= 0) {
278	<	synchronized(this) {
279	<	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){
280	<	boolean interrupted = false;
281	<	do {
282	<	try {
283	<	wait();
284	<	} catch (InterruptedException ie) {
285	<	interrupted = true;
286	<	}
287	<	} while ((s = status) >= 0);
288	<	if (interrupted)
289	<	Thread.currentThread().interrupt();
264	<	break;
277	>	if (Thread.interrupted())
278	>	throw new InterruptedException();
279	>	if ((s = status) >= 0) {
280	>	synchronized (this) {
281	>	while ((s = status) >= 0) {
282	>	if (s == 0)
283	>	UNSAFE.compareAndSwapInt(this, statusOffset,
284	>	0, SIGNAL);
285	>	else {
286	>	wait(millis);
287	>	if (millis > 0L)
288	>	break;
289	>	}
290		}
291		}
292		}
#	Line 269 | Line 294 | public abstract class ForkJoinTask<V> im
294		}
295
296		/**
297	<	* Unless done, calls exec and records status if completed, but
298	<	* doesn't wait for completion otherwise.
297	>	* Primary execution method for stolen tasks. Unless done, calls
298	>	* exec and records status if completed, but doesn't wait for
299	>	* completion otherwise.
300		*/
301	<	final void tryExec() {
302	<	try {
303	<	if (status < 0 || !exec())
301	>	final void doExec() {
302	>	if (status >= 0) {
303	>	boolean completed;
304	>	try {
305	>	completed = exec();
306	>	} catch (Throwable rex) {
307	>	setExceptionalCompletion(rex);
308		return;
309	<	} catch (Throwable rex) {
310	<	setExceptionalCompletion(rex);
311	<	return;
309	>	}
310	>	if (completed)
311	>	setCompletion(NORMAL); // must be outside try block
312		}
283	–	setCompletion(NORMAL); // must be outside try block
313		}
314
315		/**
316	<	* If not done and this task is next in worker queue, runs it,
317	<	* else waits for it.
289	<	* @return status on exit
316	>	* Primary mechanics for join, get, quietlyJoin.
317	>	* @return status upon completion
318		*/
319	<	private int waitingJoin() {
320	<	int s = status;
321	<	if (s < 0)
322	<	return s;
323	<	Thread t = Thread.currentThread();
324	<	if (t instanceof ForkJoinWorkerThread) {
297	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
298	<	if (w.unpushTask(this)) {
299	<	boolean completed;
319	>	private int doJoin() {
320	>	Thread t; ForkJoinWorkerThread w; int s; boolean completed;
321	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
322	>	if ((s = status) < 0)
323	>	return s;
324	>	if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) {
325		try {
326		completed = exec();
327		} catch (Throwable rex) {
#	Line 305 | Line 330 | public abstract class ForkJoinTask<V> im
330		if (completed)
331		return setCompletion(NORMAL);
332		}
333	<	return w.pool.awaitJoin(this);
333	>	return w.joinTask(this);
334		}
335		else
336		return externalAwaitDone();
337		}
338
339		/**
340	<	* Unless done, calls exec and records status if completed, or
341	<	* waits for completion otherwise.
317	<	* @return status on exit
340	>	* Primary mechanics for invoke, quietlyInvoke.
341	>	* @return status upon completion
342		*/
343	<	private int waitingInvoke() {
344	<	int s = status;
345	<	if (s < 0)
343	>	private int doInvoke() {
344	>	int s; boolean completed;
345	>	if ((s = status) < 0)
346		return s;
323	–	boolean completed;
347		try {
348		completed = exec();
349		} catch (Throwable rex) {
#	Line 328 | Line 351 | public abstract class ForkJoinTask<V> im
351		}
352		if (completed)
353		return setCompletion(NORMAL);
354	<	return waitingJoin();
354	>	else
355	>	return doJoin();
356	>	}
357	>
358	>	// Exception table support
359	>
360	>	/**
361	>	* Table of exceptions thrown by tasks, to enable reporting by
362	>	* callers. Because exceptions are rare, we don't directly keep
363	>	* them with task objects, but instead use a weak ref table.  Note
364	>	* that cancellation exceptions don't appear in the table, but are
365	>	* instead recorded as status values.
366	>	*
367	>	* Note: These statics are initialized below in static block.
368	>	*/
369	>	private static final ExceptionNode[] exceptionTable;
370	>	private static final ReentrantLock exceptionTableLock;
371	>	private static final ReferenceQueue<Object> exceptionTableRefQueue;
372	>
373	>	/**
374	>	* Fixed capacity for exceptionTable.
375	>	*/
376	>	private static final int EXCEPTION_MAP_CAPACITY = 32;
377	>
378	>	/**
379	>	* Key-value nodes for exception table.  The chained hash table
380	>	* uses identity comparisons, full locking, and weak references
381	>	* for keys. The table has a fixed capacity because it only
382	>	* maintains task exceptions long enough for joiners to access
383	>	* them, so should never become very large for sustained
384	>	* periods. However, since we do not know when the last joiner
385	>	* completes, we must use weak references and expunge them. We do
386	>	* so on each operation (hence full locking). Also, some thread in
387	>	* any ForkJoinPool will call helpExpungeStaleExceptions when its
388	>	* pool becomes isQuiescent.
389	>	*/
390	>	static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{
391	>	final Throwable ex;
392	>	ExceptionNode next;
393	>	final long thrower;  // use id not ref to avoid weak cycles
394	>	ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
395	>	super(task, exceptionTableRefQueue);
396	>	this.ex = ex;
397	>	this.next = next;
398	>	this.thrower = Thread.currentThread().getId();
399	>	}
400		}
401
402		/**
403	<	* If this task is next in worker queue, runs it, else processes other
404	<	* tasks until complete.
403	>	* Records exception and sets exceptional completion.
404	>	*
405		* @return status on exit
406		*/
407	<	private int busyJoin() {
408	<	int s = status;
409	<	if (s < 0)
410	<	return s;
411	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread();
412	<	if (w.unpushTask(this)) {
413	<	boolean completed;
414	<	try {
415	<	completed = exec();
416	<	} catch (Throwable rex) {
417	<	return setExceptionalCompletion(rex);
407	>	private int setExceptionalCompletion(Throwable ex) {
408	>	int h = System.identityHashCode(this);
409	>	final ReentrantLock lock = exceptionTableLock;
410	>	lock.lock();
411	>	try {
412	>	expungeStaleExceptions();
413	>	ExceptionNode[] t = exceptionTable;
414	>	int i = h & (t.length - 1);
415	>	for (ExceptionNode e = t[i]; ; e = e.next) {
416	>	if (e == null) {
417	>	t[i] = new ExceptionNode(this, ex, t[i]);
418	>	break;
419	>	}
420	>	if (e.get() == this) // already present
421	>	break;
422		}
423	<	if (completed)
424	<	return setCompletion(NORMAL);
423	>	} finally {
424	>	lock.unlock();
425		}
426	<	return w.execWhileJoining(this);
426	>	return setCompletion(EXCEPTIONAL);
427		}
428
429		/**
430	<	* Returns result or throws exception associated with given status.
359	<	* @param s the status
430	>	* Removes exception node and clears status
431		*/
432	<	private V reportResult(int s) {
432	>	private void clearExceptionalCompletion() {
433	>	int h = System.identityHashCode(this);
434	>	final ReentrantLock lock = exceptionTableLock;
435	>	lock.lock();
436	>	try {
437	>	ExceptionNode[] t = exceptionTable;
438	>	int i = h & (t.length - 1);
439	>	ExceptionNode e = t[i];
440	>	ExceptionNode pred = null;
441	>	while (e != null) {
442	>	ExceptionNode next = e.next;
443	>	if (e.get() == this) {
444	>	if (pred == null)
445	>	t[i] = next;
446	>	else
447	>	pred.next = next;
448	>	break;
449	>	}
450	>	pred = e;
451	>	e = next;
452	>	}
453	>	expungeStaleExceptions();
454	>	status = 0;
455	>	} finally {
456	>	lock.unlock();
457	>	}
458	>	}
459	>
460	>	/**
461	>	* Returns a rethrowable exception for the given task, if
462	>	* available. To provide accurate stack traces, if the exception
463	>	* was not thrown by the current thread, we try to create a new
464	>	* exception of the same type as the one thrown, but with the
465	>	* recorded exception as its cause. If there is no such
466	>	* constructor, we instead try to use a no-arg constructor,
467	>	* followed by initCause, to the same effect. If none of these
468	>	* apply, or any fail due to other exceptions, we return the
469	>	* recorded exception, which is still correct, although it may
470	>	* contain a misleading stack trace.
471	>	*
472	>	* @return the exception, or null if none
473	>	*/
474	>	private Throwable getThrowableException() {
475	>	if (status != EXCEPTIONAL)
476	>	return null;
477	>	int h = System.identityHashCode(this);
478	>	ExceptionNode e;
479	>	final ReentrantLock lock = exceptionTableLock;
480	>	lock.lock();
481	>	try {
482	>	expungeStaleExceptions();
483	>	ExceptionNode[] t = exceptionTable;
484	>	e = t[h & (t.length - 1)];
485	>	while (e != null && e.get() != this)
486	>	e = e.next;
487	>	} finally {
488	>	lock.unlock();
489	>	}
490		Throwable ex;
491	<	if (s < NORMAL && (ex = getException()) != null)
491	>	if (e == null || (ex = e.ex) == null)
492	>	return null;
493	>	if (e.thrower != Thread.currentThread().getId()) {
494	>	Class ec = ex.getClass();
495	>	try {
496	>	Constructor<?> noArgCtor = null;
497	>	Constructor<?>[] cs = ec.getConstructors();// public ctors only
498	>	for (int i = 0; i < cs.length; ++i) {
499	>	Constructor<?> c = cs[i];
500	>	Class<?>[] ps = c.getParameterTypes();
501	>	if (ps.length == 0)
502	>	noArgCtor = c;
503	>	else if (ps.length == 1 && ps[0] == Throwable.class)
504	>	return (Throwable)(c.newInstance(ex));
505	>	}
506	>	if (noArgCtor != null) {
507	>	Throwable wx = (Throwable)(noArgCtor.newInstance());
508	>	wx.initCause(ex);
509	>	return wx;
510	>	}
511	>	} catch (Exception ignore) {
512	>	}
513	>	}
514	>	return ex;
515	>	}
516	>
517	>	/**
518	>	* Poll stale refs and remove them. Call only while holding lock.
519	>	*/
520	>	private static void expungeStaleExceptions() {
521	>	for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
522	>	if (x instanceof ExceptionNode) {
523	>	ForkJoinTask<?> key = ((ExceptionNode)x).get();
524	>	ExceptionNode[] t = exceptionTable;
525	>	int i = System.identityHashCode(key) & (t.length - 1);
526	>	ExceptionNode e = t[i];
527	>	ExceptionNode pred = null;
528	>	while (e != null) {
529	>	ExceptionNode next = e.next;
530	>	if (e == x) {
531	>	if (pred == null)
532	>	t[i] = next;
533	>	else
534	>	pred.next = next;
535	>	break;
536	>	}
537	>	pred = e;
538	>	e = next;
539	>	}
540	>	}
541	>	}
542	>	}
543	>
544	>	/**
545	>	* If lock is available, poll stale refs and remove them.
546	>	* Called from ForkJoinPool when pools become quiescent.
547	>	*/
548	>	static final void helpExpungeStaleExceptions() {
549	>	final ReentrantLock lock = exceptionTableLock;
550	>	if (lock.tryLock()) {
551	>	try {
552	>	expungeStaleExceptions();
553	>	} finally {
554	>	lock.unlock();
555	>	}
556	>	}
557	>	}
558	>
559	>	/**
560	>	* Report the result of invoke or join; called only upon
561	>	* non-normal return of internal versions.
562	>	*/
563	>	private V reportResult() {
564	>	int s; Throwable ex;
565	>	if ((s = status) == CANCELLED)
566	>	throw new CancellationException();
567	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
568		UNSAFE.throwException(ex);
569		return getRawResult();
570		}
#	Line 378 | Line 582 | public abstract class ForkJoinTask<V> im
582		* #isDone} returning {@code true}.
583		*
584		* <p>This method may be invoked only from within {@code
585	<	* ForkJoinTask} computations (as may be determined using method
585	>	* ForkJoinPool} computations (as may be determined using method
586		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
587		* result in exceptions or errors, possibly including {@code
588		* ClassCastException}.
#	Line 392 | Line 596 | public abstract class ForkJoinTask<V> im
596		}
597
598		/**
599	<	* Returns the result of the computation when it {@link #isDone is done}.
600	<	* This method differs from {@link #get()} in that
599	>	* Returns the result of the computation when it {@link #isDone is
600	>	* done}.  This method differs from {@link #get()} in that
601		* abnormal completion results in {@code RuntimeException} or
602	<	* {@code Error}, not {@code ExecutionException}.
602	>	* {@code Error}, not {@code ExecutionException}, and that
603	>	* interrupts of the calling thread do <em>not</em> cause the
604	>	* method to abruptly return by throwing {@code
605	>	* InterruptedException}.
606		*
607		* @return the computed result
608		*/
609		public final V join() {
610	<	return reportResult(waitingJoin());
610	>	if (doJoin() != NORMAL)
611	>	return reportResult();
612	>	else
613	>	return getRawResult();
614		}
615
616		/**
617		* Commences performing this task, awaits its completion if
618	<	* necessary, and return its result, or throws an (unchecked)
619	<	* exception if the underlying computation did so.
618	>	* necessary, and returns its result, or throws an (unchecked)
619	>	* {@code RuntimeException} or {@code Error} if the underlying
620	>	* computation did so.
621		*
622		* @return the computed result
623		*/
624		public final V invoke() {
625	<	return reportResult(waitingInvoke());
625	>	if (doInvoke() != NORMAL)
626	>	return reportResult();
627	>	else
628	>	return getRawResult();
629		}
630
631		/**
632		* Forks the given tasks, returning when {@code isDone} holds for
633		* each task or an (unchecked) exception is encountered, in which
634	<	* case the exception is rethrown.  If either task encounters an
635	<	* exception, the other one may be, but is not guaranteed to be,
636	<	* cancelled.  If both tasks throw an exception, then this method
637	<	* throws one of them.  The individual status of each task may be
638	<	* checked using {@link #getException()} and related methods.
634	>	* case the exception is rethrown. If more than one task
635	>	* encounters an exception, then this method throws any one of
636	>	* these exceptions. If any task encounters an exception, the
637	>	* other may be cancelled. However, the execution status of
638	>	* individual tasks is not guaranteed upon exceptional return. The
639	>	* status of each task may be obtained using {@link
640	>	* #getException()} and related methods to check if they have been
641	>	* cancelled, completed normally or exceptionally, or left
642	>	* unprocessed.
643		*
644		* <p>This method may be invoked only from within {@code
645	<	* ForkJoinTask} computations (as may be determined using method
645	>	* ForkJoinPool} computations (as may be determined using method
646		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
647		* result in exceptions or errors, possibly including {@code
648		* ClassCastException}.
#	Line 442 | Line 660 | public abstract class ForkJoinTask<V> im
660		/**
661		* Forks the given tasks, returning when {@code isDone} holds for
662		* each task or an (unchecked) exception is encountered, in which
663	<	* case the exception is rethrown. If any task encounters an
664	<	* exception, others may be, but are not guaranteed to be,
665	<	* cancelled.  If more than one task encounters an exception, then
666	<	* this method throws any one of these exceptions.  The individual
667	<	* status of each task may be checked using {@link #getException()}
668	<	* and related methods.
663	>	* case the exception is rethrown. If more than one task
664	>	* encounters an exception, then this method throws any one of
665	>	* these exceptions. If any task encounters an exception, others
666	>	* may be cancelled. However, the execution status of individual
667	>	* tasks is not guaranteed upon exceptional return. The status of
668	>	* each task may be obtained using {@link #getException()} and
669	>	* related methods to check if they have been cancelled, completed
670	>	* normally or exceptionally, or left unprocessed.
671		*
672		* <p>This method may be invoked only from within {@code
673	<	* ForkJoinTask} computations (as may be determined using method
673	>	* ForkJoinPool} computations (as may be determined using method
674		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
675		* result in exceptions or errors, possibly including {@code
676		* ClassCastException}.
#	Line 469 | Line 689 | public abstract class ForkJoinTask<V> im
689		}
690		else if (i != 0)
691		t.fork();
692	<	else if (t.waitingInvoke() < NORMAL && ex == null)
692	>	else if (t.doInvoke() < NORMAL && ex == null)
693		ex = t.getException();
694		}
695		for (int i = 1; i <= last; ++i) {
#	Line 477 | Line 697 | public abstract class ForkJoinTask<V> im
697		if (t != null) {
698		if (ex != null)
699		t.cancel(false);
700	<	else if (t.waitingJoin() < NORMAL && ex == null)
700	>	else if (t.doJoin() < NORMAL && ex == null)
701		ex = t.getException();
702		}
703		}
#	Line 488 | Line 708 | public abstract class ForkJoinTask<V> im
708		/**
709		* Forks all tasks in the specified collection, returning when
710		* {@code isDone} holds for each task or an (unchecked) exception
711	<	* is encountered.  If any task encounters an exception, others
712	<	* may be, but are not guaranteed to be, cancelled.  If more than
713	<	* one task encounters an exception, then this method throws any
714	<	* one of these exceptions.  The individual status of each task
715	<	* may be checked using {@link #getException()} and related
716	<	* methods.  The behavior of this operation is undefined if the
717	<	* specified collection is modified while the operation is in
718	<	* progress.
711	>	* is encountered, in which case the exception is rethrown. If
712	>	* more than one task encounters an exception, then this method
713	>	* throws any one of these exceptions. If any task encounters an
714	>	* exception, others may be cancelled. However, the execution
715	>	* status of individual tasks is not guaranteed upon exceptional
716	>	* return. The status of each task may be obtained using {@link
717	>	* #getException()} and related methods to check if they have been
718	>	* cancelled, completed normally or exceptionally, or left
719	>	* unprocessed.
720		*
721		* <p>This method may be invoked only from within {@code
722	<	* ForkJoinTask} computations (as may be determined using method
722	>	* ForkJoinPool} computations (as may be determined using method
723		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
724		* result in exceptions or errors, possibly including {@code
725		* ClassCastException}.
#	Line 525 | Line 746 | public abstract class ForkJoinTask<V> im
746		}
747		else if (i != 0)
748		t.fork();
749	<	else if (t.waitingInvoke() < NORMAL && ex == null)
749	>	else if (t.doInvoke() < NORMAL && ex == null)
750		ex = t.getException();
751		}
752		for (int i = 1; i <= last; ++i) {
#	Line 533 | Line 754 | public abstract class ForkJoinTask<V> im
754		if (t != null) {
755		if (ex != null)
756		t.cancel(false);
757	<	else if (t.waitingJoin() < NORMAL && ex == null)
757	>	else if (t.doJoin() < NORMAL && ex == null)
758		ex = t.getException();
759		}
760		}
#	Line 544 | Line 765 | public abstract class ForkJoinTask<V> im
765
766		/**
767		* Attempts to cancel execution of this task. This attempt will
768	<	* fail if the task has already completed, has already been
769	<	* cancelled, or could not be cancelled for some other reason. If
770	<	* successful, and this task has not started when cancel is
771	<	* called, execution of this task is suppressed, {@link
772	<	* #isCancelled} will report true, and {@link #join} will result
773	<	* in a {@code CancellationException} being thrown.
768	>	* fail if the task has already completed or could not be
769	>	* cancelled for some other reason. If successful, and this task
770	>	* has not started when {@code cancel} is called, execution of
771	>	* this task is suppressed. After this method returns
772	>	* successfully, unless there is an intervening call to {@link
773	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
774	>	* {@link #isDone}, and {@code cancel} will return {@code true}
775	>	* and calls to {@link #join} and related methods will result in
776	>	* {@code CancellationException}.
777		*
778		* <p>This method may be overridden in subclasses, but if so, must
779	<	* still ensure that these minimal properties hold. In particular,
780	<	* the {@code cancel} method itself must not throw exceptions.
779	>	* still ensure that these properties hold. In particular, the
780	>	* {@code cancel} method itself must not throw exceptions.
781		*
782		* <p>This method is designed to be invoked by <em>other</em>
783		* tasks. To terminate the current task, you can just return or
784		* throw an unchecked exception from its computation method, or
785		* invoke {@link #completeExceptionally}.
786		*
787	<	* @param mayInterruptIfRunning this value is ignored in the
788	<	* default implementation because tasks are not
789	<	* cancelled via interruption
787	>	* @param mayInterruptIfRunning this value has no effect in the
788	>	* default implementation because interrupts are not used to
789	>	* control cancellation.
790		*
791		* @return {@code true} if this task is now cancelled
792		*/
793		public boolean cancel(boolean mayInterruptIfRunning) {
794	<	setCompletion(CANCELLED);
571	<	return (status & COMPLETION_MASK) == CANCELLED;
794	>	return setCompletion(CANCELLED) == CANCELLED;
795		}
796
797		/**
798	<	* Cancels, ignoring any exceptions it throws. Used during worker
799	<	* and pool shutdown.
798	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
799	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
800	>	* exceptions, but if it does anyway, we have no recourse during
801	>	* shutdown, so guard against this case.
802		*/
803		final void cancelIgnoringExceptions() {
804		try {
#	Line 582 | Line 807 | public abstract class ForkJoinTask<V> im
807		}
808		}
809
585	–	/**
586	–	* Cancels ignoring exceptions if worker is terminating
587	–	*/
588	–	private void cancelIfTerminating() {
589	–	Thread t = Thread.currentThread();
590	–	if ((t instanceof ForkJoinWorkerThread) &&
591	–	((ForkJoinWorkerThread) t).isTerminating()) {
592	–	try {
593	–	cancel(false);
594	–	} catch (Throwable ignore) {
595	–	}
596	–	}
597	–	}
598	–
810		public final boolean isDone() {
811		return status < 0;
812		}
813
814		public final boolean isCancelled() {
815	<	return (status & COMPLETION_MASK) == CANCELLED;
815	>	return status == CANCELLED;
816		}
817
818		/**
#	Line 610 | Line 821 | public abstract class ForkJoinTask<V> im
821		* @return {@code true} if this task threw an exception or was cancelled
822		*/
823		public final boolean isCompletedAbnormally() {
824	<	return (status & COMPLETION_MASK) < NORMAL;
824	>	return status < NORMAL;
825		}
826
827		/**
#	Line 621 | Line 832 | public abstract class ForkJoinTask<V> im
832		* exception and was not cancelled
833		*/
834		public final boolean isCompletedNormally() {
835	<	return (status & COMPLETION_MASK) == NORMAL;
835	>	return status == NORMAL;
836		}
837
838		/**
#	Line 632 | Line 843 | public abstract class ForkJoinTask<V> im
843		* @return the exception, or {@code null} if none
844		*/
845		public final Throwable getException() {
846	<	int s = status & COMPLETION_MASK;
846	>	int s = status;
847		return ((s >= NORMAL)    ? null :
848		(s == CANCELLED) ? new CancellationException() :
849	<	exceptionMap.get(this));
849	>	getThrowableException());
850		}
851
852		/**
#	Line 660 | Line 871 | public abstract class ForkJoinTask<V> im
871
872		/**
873		* Completes this task, and if not already aborted or cancelled,
874	<	* returning a {@code null} result upon {@code join} and related
875	<	* operations. This method may be used to provide results for
876	<	* asynchronous tasks, or to provide alternative handling for
877	<	* tasks that would not otherwise complete normally. Its use in
878	<	* other situations is discouraged. This method is
879	<	* overridable, but overridden versions must invoke {@code super}
880	<	* implementation to maintain guarantees.
874	>	* returning the given value as the result of subsequent
875	>	* invocations of {@code join} and related operations. This method
876	>	* may be used to provide results for asynchronous tasks, or to
877	>	* provide alternative handling for tasks that would not otherwise
878	>	* complete normally. Its use in other situations is
879	>	* discouraged. This method is overridable, but overridden
880	>	* versions must invoke {@code super} implementation to maintain
881	>	* guarantees.
882		*
883		* @param value the result value for this task
884		*/
#	Line 680 | Line 892 | public abstract class ForkJoinTask<V> im
892		setCompletion(NORMAL);
893		}
894
895	+	/**
896	+	* Waits if necessary for the computation to complete, and then
897	+	* retrieves its result.
898	+	*
899	+	* @return the computed result
900	+	* @throws CancellationException if the computation was cancelled
901	+	* @throws ExecutionException if the computation threw an
902	+	* exception
903	+	* @throws InterruptedException if the current thread is not a
904	+	* member of a ForkJoinPool and was interrupted while waiting
905	+	*/
906		public final V get() throws InterruptedException, ExecutionException {
907	<	int s = waitingJoin() & COMPLETION_MASK;
908	<	if (Thread.interrupted())
909	<	throw new InterruptedException();
910	<	if (s < NORMAL) {
911	<	Throwable ex;
912	<	if (s == CANCELLED)
913	<	throw new CancellationException();
691	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
692	<	throw new ExecutionException(ex);
693	<	}
907	>	int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ?
908	>	doJoin() : externalInterruptibleAwaitDone(0L);
909	>	Throwable ex;
910	>	if (s == CANCELLED)
911	>	throw new CancellationException();
912	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
913	>	throw new ExecutionException(ex);
914		return getRawResult();
915		}
916
917	+	/**
918	+	* Waits if necessary for at most the given time for the computation
919	+	* to complete, and then retrieves its result, if available.
920	+	*
921	+	* @param timeout the maximum time to wait
922	+	* @param unit the time unit of the timeout argument
923	+	* @return the computed result
924	+	* @throws CancellationException if the computation was cancelled
925	+	* @throws ExecutionException if the computation threw an
926	+	* exception
927	+	* @throws InterruptedException if the current thread is not a
928	+	* member of a ForkJoinPool and was interrupted while waiting
929	+	* @throws TimeoutException if the wait timed out
930	+	*/
931		public final V get(long timeout, TimeUnit unit)
932		throws InterruptedException, ExecutionException, TimeoutException {
933		Thread t = Thread.currentThread();
700	–	ForkJoinPool pool;
934		if (t instanceof ForkJoinWorkerThread) {
935		ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
936	<	if (status >= 0 && w.unpushTask(this))
937	<	tryExec();
938	<	pool = w.pool;
939	<	}
940	<	else
941	<	pool = null;
942	<	/*
943	<	* Timed wait loop intermixes cases for fj (pool != null) and
711	<	* non FJ threads. For FJ, decrement pool count but don't try
712	<	* for replacement; increment count on completion. For non-FJ,
713	<	* deal with interrupts. This is messy, but a little less so
714	<	* than is splitting the FJ and nonFJ cases.
715	<	*/
716	<	boolean interrupted = false;
717	<	boolean dec = false; // true if pool count decremented
718	<	for (;;) {
719	<	if (Thread.interrupted() && pool == null) {
720	<	interrupted = true;
721	<	break;
722	<	}
723	<	int s = status;
724	<	if (s < 0)
725	<	break;
726	<	if (UNSAFE.compareAndSwapInt(this, statusOffset,
727	<	s, s | SIGNAL)) {
728	<	long startTime = System.nanoTime();
729	<	long nanos = unit.toNanos(timeout);
730	<	long nt; // wait time
731	<	while (status >= 0 &&
732	<	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
733	<	if (pool != null && !dec)
734	<	dec = pool.tryDecrementRunningCount();
735	<	else {
736	<	long ms = nt / 1000000;
737	<	int ns = (int) (nt % 1000000);
738	<	try {
739	<	synchronized(this) {
740	<	if (status >= 0)
741	<	wait(ms, ns);
742	<	}
743	<	} catch (InterruptedException ie) {
744	<	if (pool != null)
745	<	cancelIfTerminating();
746	<	else {
747	<	interrupted = true;
748	<	break;
749	<	}
750	<	}
936	>	long nanos = unit.toNanos(timeout);
937	>	if (status >= 0) {
938	>	boolean completed = false;
939	>	if (w.unpushTask(this)) {
940	>	try {
941	>	completed = exec();
942	>	} catch (Throwable rex) {
943	>	setExceptionalCompletion(rex);
944		}
945		}
946	<	break;
946	>	if (completed)
947	>	setCompletion(NORMAL);
948	>	else if (status >= 0 && nanos > 0)
949	>	w.pool.timedAwaitJoin(this, nanos);
950		}
951		}
952	<	if (pool != null && dec)
953	<	pool.updateRunningCount(1);
954	<	if (interrupted)
955	<	throw new InterruptedException();
956	<	int es = status & COMPLETION_MASK;
957	<	if (es != NORMAL) {
952	>	else {
953	>	long millis = unit.toMillis(timeout);
954	>	if (millis > 0)
955	>	externalInterruptibleAwaitDone(millis);
956	>	}
957	>	int s = status;
958	>	if (s != NORMAL) {
959		Throwable ex;
960	<	if (es == CANCELLED)
960	>	if (s == CANCELLED)
961		throw new CancellationException();
962	<	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
962	>	if (s != EXCEPTIONAL)
963	>	throw new TimeoutException();
964	>	if ((ex = getThrowableException()) != null)
965		throw new ExecutionException(ex);
767	–	throw new TimeoutException();
966		}
967		return getRawResult();
968		}
969
970		/**
971	<	* Possibly executes other tasks until this task {@link #isDone is
774	<	* done}, then returns the result of the computation.  This method
775	<	* may be more efficient than {@code join}, but is only applicable
776	<	* when there are no potential dependencies between continuation
777	<	* of the current task and that of any other task that might be
778	<	* executed while helping. (This usually holds for pure
779	<	* divide-and-conquer tasks).
780	<	*
781	<	* <p>This method may be invoked only from within {@code
782	<	* ForkJoinTask} computations (as may be determined using method
783	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
784	<	* result in exceptions or errors, possibly including {@code
785	<	* ClassCastException}.
786	<	*
787	<	* @return the computed result
788	<	*/
789	<	public final V helpJoin() {
790	<	return reportResult(busyJoin());
791	<	}
792	<
793	<	/**
794	<	* Possibly executes other tasks until this task {@link #isDone is
795	<	* done}.  This method may be useful when processing collections
796	<	* of tasks when some have been cancelled or otherwise known to
797	<	* have aborted.
798	<	*
799	<	* <p>This method may be invoked only from within {@code
800	<	* ForkJoinTask} computations (as may be determined using method
801	<	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
802	<	* result in exceptions or errors, possibly including {@code
803	<	* ClassCastException}.
804	<	*/
805	<	public final void quietlyHelpJoin() {
806	<	busyJoin();
807	<	}
808	<
809	<	/**
810	<	* Joins this task, without returning its result or throwing an
971	>	* Joins this task, without returning its result or throwing its
972		* exception. This method may be useful when processing
973		* collections of tasks when some have been cancelled or otherwise
974		* known to have aborted.
975		*/
976		public final void quietlyJoin() {
977	<	waitingJoin();
977	>	doJoin();
978		}
979
980		/**
981		* Commences performing this task and awaits its completion if
982	<	* necessary, without returning its result or throwing an
983	<	* exception. This method may be useful when processing
823	<	* collections of tasks when some have been cancelled or otherwise
824	<	* known to have aborted.
982	>	* necessary, without returning its result or throwing its
983	>	* exception.
984		*/
985		public final void quietlyInvoke() {
986	<	waitingInvoke();
986	>	doInvoke();
987		}
988
989		/**
#	Line 835 | Line 994 | public abstract class ForkJoinTask<V> im
994		* processed.
995		*
996		* <p>This method may be invoked only from within {@code
997	<	* ForkJoinTask} computations (as may be determined using method
997	>	* ForkJoinPool} computations (as may be determined using method
998		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
999		* result in exceptions or errors, possibly including {@code
1000		* ClassCastException}.
#	Line 854 | Line 1013 | public abstract class ForkJoinTask<V> im
1013		* under any other usage conditions are not guaranteed.
1014		* This method may be useful when executing
1015		* pre-constructed trees of subtasks in loops.
1016	+	*
1017	+	* <p>Upon completion of this method, {@code isDone()} reports
1018	+	* {@code false}, and {@code getException()} reports {@code
1019	+	* null}. However, the value returned by {@code getRawResult} is
1020	+	* unaffected. To clear this value, you can invoke {@code
1021	+	* setRawResult(null)}.
1022		*/
1023		public void reinitialize() {
1024	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
1025	<	exceptionMap.remove(this);
1026	<	status = 0;
1024	>	if (status == EXCEPTIONAL)
1025	>	clearExceptionalCompletion();
1026	>	else
1027	>	status = 0;
1028		}
1029
1030		/**
#	Line 875 | Line 1041 | public abstract class ForkJoinTask<V> im
1041		}
1042
1043		/**
1044	<	* Returns {@code true} if the current thread is executing as a
1045	<	* ForkJoinPool computation.
1044	>	* Returns {@code true} if the current thread is a {@link
1045	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
1046		*
1047	<	* @return {@code true} if the current thread is executing as a
1048	<	* ForkJoinPool computation, or false otherwise
1047	>	* @return {@code true} if the current thread is a {@link
1048	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
1049	>	* or {@code false} otherwise
1050		*/
1051		public static boolean inForkJoinPool() {
1052		return Thread.currentThread() instanceof ForkJoinWorkerThread;
#	Line 894 | Line 1061 | public abstract class ForkJoinTask<V> im
1061		* were not, stolen.
1062		*
1063		* <p>This method may be invoked only from within {@code
1064	<	* ForkJoinTask} computations (as may be determined using method
1064	>	* ForkJoinPool} computations (as may be determined using method
1065		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1066		* result in exceptions or errors, possibly including {@code
1067		* ClassCastException}.
#	Line 913 | Line 1080 | public abstract class ForkJoinTask<V> im
1080		* fork other tasks.
1081		*
1082		* <p>This method may be invoked only from within {@code
1083	<	* ForkJoinTask} computations (as may be determined using method
1083	>	* ForkJoinPool} computations (as may be determined using method
1084		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1085		* result in exceptions or errors, possibly including {@code
1086		* ClassCastException}.
#	Line 936 | Line 1103 | public abstract class ForkJoinTask<V> im
1103		* exceeded.
1104		*
1105		* <p>This method may be invoked only from within {@code
1106	<	* ForkJoinTask} computations (as may be determined using method
1106	>	* ForkJoinPool} computations (as may be determined using method
1107		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1108		* result in exceptions or errors, possibly including {@code
1109		* ClassCastException}.
#	Line 994 | Line 1161 | public abstract class ForkJoinTask<V> im
1161		* otherwise.
1162		*
1163		* <p>This method may be invoked only from within {@code
1164	<	* ForkJoinTask} computations (as may be determined using method
1164	>	* ForkJoinPool} computations (as may be determined using method
1165		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1166		* result in exceptions or errors, possibly including {@code
1167		* ClassCastException}.
#	Line 1013 | Line 1180 | public abstract class ForkJoinTask<V> im
1180		* be useful otherwise.
1181		*
1182		* <p>This method may be invoked only from within {@code
1183	<	* ForkJoinTask} computations (as may be determined using method
1183	>	* ForkJoinPool} computations (as may be determined using method
1184		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1185		* result in exceptions or errors, possibly including {@code
1186		* ClassCastException}.
#	Line 1036 | Line 1203 | public abstract class ForkJoinTask<V> im
1203		* otherwise.
1204		*
1205		* <p>This method may be invoked only from within {@code
1206	<	* ForkJoinTask} computations (as may be determined using method
1206	>	* ForkJoinPool} computations (as may be determined using method
1207		* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1208		* result in exceptions or errors, possibly including {@code
1209		* ClassCastException}.
#	Line 1146 | Line 1313 | public abstract class ForkJoinTask<V> im
1313		private static final long serialVersionUID = -7721805057305804111L;
1314
1315		/**
1316	<	* Saves the state to a stream.
1316	>	* Saves the state to a stream (that is, serializes it).
1317		*
1318		* @serialData the current run status and the exception thrown
1319		* during execution, or {@code null} if none
#	Line 1159 | Line 1326 | public abstract class ForkJoinTask<V> im
1326		}
1327
1328		/**
1329	<	* Reconstitutes the instance from a stream.
1329	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1330		*
1331		* @param s the stream
1332		*/
1333		private void readObject(java.io.ObjectInputStream s)
1334		throws java.io.IOException, ClassNotFoundException {
1335		s.defaultReadObject();
1169	–	status |= SIGNAL; // conservatively set external signal
1336		Object ex = s.readObject();
1337		if (ex != null)
1338	<	setExceptionalCompletion((Throwable) ex);
1338	>	setExceptionalCompletion((Throwable)ex);
1339		}
1340
1341		// Unsafe mechanics
1342	<
1343	<	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1344	<	private static final long statusOffset =
1345	<	objectFieldOffset("status", ForkJoinTask.class);
1346	<
1347	<	private static long objectFieldOffset(String field, Class<?> klazz) {
1342	>	private static final sun.misc.Unsafe UNSAFE;
1343	>	private static final long statusOffset;
1344	>	static {
1345	>	exceptionTableLock = new ReentrantLock();
1346	>	exceptionTableRefQueue = new ReferenceQueue<Object>();
1347	>	exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY];
1348		try {
1349	<	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1350	<	} catch (NoSuchFieldException e) {
1351	<	// Convert Exception to corresponding Error
1352	<	NoSuchFieldError error = new NoSuchFieldError(field);
1353	<	error.initCause(e);
1188	<	throw error;
1349	>	UNSAFE = getUnsafe();
1350	>	statusOffset = UNSAFE.objectFieldOffset
1351	>	(ForkJoinTask.class.getDeclaredField("status"));
1352	>	} catch (Exception e) {
1353	>	throw new Error(e);
1354		}
1355		}
1356

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