ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

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

Comparing jsr166/src/jsr166y/ForkJoinTask.java (file contents):
Revision 1.1 by dl, Tue Jan 6 14:30:31 2009 UTC vs.
Revision 1.69 by dl, Mon Nov 22 12:24:34 2010 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	+
9		import java.io.Serializable;
10	<	import java.util.*;
11	<	import java.util.concurrent.*;
12	<	import java.util.concurrent.atomic.*;
13	<	import sun.misc.Unsafe;
14	<	import java.lang.reflect.*;
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;
16	>	import java.util.concurrent.Callable;
17	>	import java.util.concurrent.CancellationException;
18	>	import java.util.concurrent.ExecutionException;
19	>	import java.util.concurrent.Executor;
20	>	import java.util.concurrent.ExecutorService;
21	>	import java.util.concurrent.Future;
22	>	import java.util.concurrent.RejectedExecutionException;
23	>	import java.util.concurrent.RunnableFuture;
24	>	import java.util.concurrent.TimeUnit;
25	>	import java.util.concurrent.TimeoutException;
26
27		/**
28	<	* Abstract base class for tasks that run within a ForkJoinPool.  A
29	<	* ForkJoinTask is a thread-like entity that is much lighter weight
30	<	* than a normal thread.  Huge numbers of tasks and subtasks may be
31	<	* hosted by a small number of actual threads in a ForkJoinPool,
32	<	* at the price of some usage limitations.
33	<	*
34	<	* <p> ForkJoinTasks are forms of <tt>Futures</tt> supporting a
35	<	* limited range of use.  The "lightness" of ForkJoinTasks is due to a
36	<	* set of restrictions (that are only partially statically
37	<	* enforceable) reflecting their intended use as computational tasks
38	<	* calculating pure functions or operating on purely isolated objects.
39	<	* The primary coordination mechanisms supported for ForkJoinTasks are
40	<	* <tt>fork</tt>, that arranges asynchronous execution, and
41	<	* <tt>join</tt>, that doesn't proceed until the task's result has
42	<	* been computed. (Cancellation is also supported).  The computation
43	<	* defined in the <tt>compute</tt> method should avoid
44	<	* <tt>synchronized</tt> methods or blocks, and should minimize
45	<	* blocking synchronization apart from joining other tasks or using
46	<	* synchronizers such as Phasers that are advertised to cooperate with
47	<	* fork/join scheduling. Tasks should also not perform blocking IO,
48	<	* and should ideally access variables that are completely independent
49	<	* of those accessed by other running tasks. Minor breaches of these
50	<	* restrictions, for example using shared output streams, may be
51	<	* tolerable in practice, but frequent use may result in poor
52	<	* performance, and the potential to indefinitely stall if the number
53	<	* of threads not waiting for external synchronization becomes
54	<	* exhausted. This usage restriction is in part enforced by not
55	<	* permitting checked exceptions such as IOExceptions to be
56	<	* thrown. However, computations may still encounter unchecked
57	<	* exceptions, that are rethrown to callers attempting join
58	<	* them. These exceptions may additionally include
59	<	* RejectedExecutionExceptions stemming from internal resource
60	<	* exhaustion such as failure to allocate internal task queues.
61	<	*
62	<	* <p> The <tt>ForkJoinTask</tt> class is not usually directly
63	<	* subclassed.  Instead, you subclass one of the abstract classes that
64	<	* support different styles of fork/join processing.  Normally, a
65	<	* concrete ForkJoinTask subclass declares fields comprising its
66	<	* parameters, established in a constructor, and then defines a
67	<	* <tt>compute</tt> method that somehow uses the control methods
68	<	* supplied by this base class. While these methods have
69	<	* <tt>public</tt> access, some of them may only be called from within
70	<	* other ForkJoinTasks. Attempts to invoke them in other contexts
71	<	* result in exceptions or errors including ClassCastException.  The
72	<	* only way to invoke a "main" driver task is to submit it to a
73	<	* ForkJoinPool. Once started, this will usually in turn start other
74	<	* subtasks.
75	<	*
76	<	* <p>Most base support methods are <tt>final</tt> because their
77	<	* implementations are intrinsically tied to the underlying
78	<	* lightweight task scheduling framework, and so cannot be overridden.
79	<	* Developers creating new basic styles of fork/join processing should
80	<	* minimally implement protected methods <tt>exec</tt>,
81	<	* <tt>setRawResult</tt>, and <tt>getRawResult</tt>, while also
82	<	* introducing an abstract computational method that can be
83	<	* implemented in its subclasses. To support such extensions,
84	<	* instances of ForkJoinTasks maintain an atomically updated
85	<	* <tt>short</tt> representing user-defined control state.  Control
86	<	* state is guaranteed initially to be zero, and to be negative upon
87	<	* completion, but may otherwise be used for any other control
88	<	* purposes, such as maintaining join counts.  The {@link
89	<	* ForkJoinWorkerThread} class supports additional inspection and
90	<	* tuning methods that can be useful when developing extensions.
28	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
29	>	* A {@code ForkJoinTask} is a thread-like entity that is much
30	>	* lighter weight than a normal thread.  Huge numbers of tasks and
31	>	* subtasks may be hosted by a small number of actual threads in a
32	>	* ForkJoinPool, at the price of some usage limitations.
33	>	*
34	>	* <p>A "main" {@code ForkJoinTask} begins execution when submitted
35	>	* to a {@link ForkJoinPool}.  Once started, it will usually in turn
36	>	* start other subtasks.  As indicated by the name of this class,
37	>	* many programs using {@code ForkJoinTask} employ only methods
38	>	* {@link #fork} and {@link #join}, or derivatives such as {@link
39	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
40	>	* provides a number of other methods that can come into play in
41	>	* advanced usages, as well as extension mechanics that allow
42	>	* support of new forms of fork/join processing.
43	>	*
44	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
45	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
46	>	* restrictions (that are only partially statically enforceable)
47	>	* reflecting their intended use as computational tasks calculating
48	>	* pure functions or operating on purely isolated objects.  The
49	>	* primary coordination mechanisms are {@link #fork}, that arranges
50	>	* asynchronous execution, and {@link #join}, that doesn't proceed
51	>	* until the task's result has been computed.  Computations should
52	>	* avoid {@code synchronized} methods or blocks, and should minimize
53	>	* other blocking synchronization apart from joining other tasks or
54	>	* using synchronizers such as Phasers that are advertised to
55	>	* cooperate with fork/join scheduling. Tasks should also not perform
56	>	* blocking IO, and should ideally access variables that are
57	>	* completely independent of those accessed by other running
58	>	* tasks. Minor breaches of these restrictions, for example using
59	>	* shared output streams, may be tolerable in practice, but frequent
60	>	* use may result in poor performance, and the potential to
61	>	* indefinitely stall if the number of threads not waiting for IO or
62	>	* other external synchronization becomes exhausted. This usage
63	>	* restriction is in part enforced by not permitting checked
64	>	* exceptions such as {@code IOExceptions} to be thrown. However,
65	>	* computations may still encounter unchecked exceptions, that are
66	>	* rethrown to callers attempting to join them. These exceptions may
67	>	* additionally include {@link RejectedExecutionException} stemming
68	>	* from internal resource exhaustion, such as failure to allocate
69	>	* internal task queues.
70	>	*
71	>	* <p>The primary method for awaiting completion and extracting
72	>	* results of a task is {@link #join}, but there are several variants:
73	>	* The {@link Future#get} methods support interruptible and/or timed
74	>	* waits for completion and report results using {@code Future}
75	>	* conventions. Method {@link #invoke} is semantically
76	>	* equivalent to {@code fork(); join()} but always attempts to begin
77	>	* execution in the current thread. The "<em>quiet</em>" forms of
78	>	* these methods do not extract results or report exceptions. These
79	>	* may be useful when a set of tasks are being executed, and you need
80	>	* to delay processing of results or exceptions until all complete.
81	>	* Method {@code invokeAll} (available in multiple versions)
82	>	* performs the most common form of parallel invocation: forking a set
83	>	* of tasks and joining them all.
84	>	*
85	>	* <p>The execution status of tasks may be queried at several levels
86	>	* of detail: {@link #isDone} is true if a task completed in any way
87	>	* (including the case where a task was cancelled without executing);
88	>	* {@link #isCompletedNormally} is true if a task completed without
89	>	* cancellation or encountering an exception; {@link #isCancelled} is
90	>	* true if the task was cancelled (in which case {@link #getException}
91	>	* returns a {@link java.util.concurrent.CancellationException}); and
92	>	* {@link #isCompletedAbnormally} is true if a task was either
93	>	* cancelled or encountered an exception, in which case {@link
94	>	* #getException} will return either the encountered exception or
95	>	* {@link java.util.concurrent.CancellationException}.
96	>	*
97	>	* <p>The ForkJoinTask class is not usually directly subclassed.
98	>	* Instead, you subclass one of the abstract classes that support a
99	>	* particular style of fork/join processing, typically {@link
100	>	* RecursiveAction} for computations that do not return results, or
101	>	* {@link RecursiveTask} for those that do.  Normally, a concrete
102	>	* ForkJoinTask subclass declares fields comprising its parameters,
103	>	* established in a constructor, and then defines a {@code compute}
104	>	* method that somehow uses the control methods supplied by this base
105	>	* class. While these methods have {@code public} access (to allow
106	>	* instances of different task subclasses to call each other's
107	>	* methods), some of them may only be called from within other
108	>	* ForkJoinTasks (as may be determined using method {@link
109	>	* #inForkJoinPool}).  Attempts to invoke them in other contexts
110	>	* result in exceptions or errors, possibly including
111	>	* {@code ClassCastException}.
112	>	*
113	>	* <p>Method {@link #join} and its variants are appropriate for use
114	>	* only when completion dependencies are acyclic; that is, the
115	>	* parallel computation can be described as a directed acyclic graph
116	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
117	>	* tasks cyclically wait for each other.  However, this framework
118	>	* supports other methods and techniques (for example the use of
119	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
120	>	* may be of use in constructing custom subclasses for problems that
121	>	* are not statically structured as DAGs.
122	>	*
123	>	* <p>Most base support methods are {@code final}, to prevent
124	>	* overriding of implementations that are intrinsically tied to the
125	>	* underlying lightweight task scheduling framework.  Developers
126	>	* creating new basic styles of fork/join processing should minimally
127	>	* implement {@code protected} methods {@link #exec}, {@link
128	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
129	>	* an abstract computational method that can be implemented in its
130	>	* subclasses, possibly relying on other {@code protected} methods
131	>	* provided by this class.
132		*
133		* <p>ForkJoinTasks should perform relatively small amounts of
134	<	* computations, othewise splitting into smaller tasks. As a very
135	<	* rough rule of thumb, a task should perform more than 100 and less
136	<	* than 10000 basic computational steps. If tasks are too big, then
137	<	* parellelism cannot improve throughput. If too small, then memory
138	<	* and internal task maintenance overhead may overwhelm processing.
139	<	*
140	<	* <p>ForkJoinTasks are <tt>Serializable</tt>, which enables them to
141	<	* be used in extensions such as remote execution frameworks. However,
142	<	* it is in general safe to serialize tasks only before or after, but
143	<	* not during execution. Serialization is not relied on during
144	<	* execution itself.
134	>	* computation. Large tasks should be split into smaller subtasks,
135	>	* usually via recursive decomposition. As a very rough rule of thumb,
136	>	* a task should perform more than 100 and less than 10000 basic
137	>	* computational steps. If tasks are too big, then parallelism cannot
138	>	* improve throughput. If too small, then memory and internal task
139	>	* maintenance overhead may overwhelm processing.
140	>	*
141	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
142	>	* and {@link Callable}, that may be of use when mixing execution of
143	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
144	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
145	>	*
146	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
147	>	* used in extensions such as remote execution frameworks. It is
148	>	* sensible to serialize tasks only before or after, but not during,
149	>	* execution. Serialization is not relied on during execution itself.
150	>	*
151	>	* @since 1.7
152	>	* @author Doug Lea
153		*/
154		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
155	<	/**
156	<	* Status field holding all run status. We pack this into a single
157	<	* int both to minimize footprint overhead and to ensure atomicity
158	<	* (updates are via CAS).
159	<	*
160	<	* Status is initially zero, and takes on nonnegative values until
161	<	* completed, upon which status holds COMPLETED. CANCELLED, or
162	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
163	<	* blocking waits by other threads have SIGNAL_MASK bits set --
164	<	* bit 15 for external (nonFJ) waits, and the rest a count of
165	<	* waiting FJ threads.  (This representation relies on
166	<	* ForkJoinPool max thread limits). Completion of a stolen task
167	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
168	<	* though suboptimal for some purposes, we use basic builtin
169	<	* wait/notify to take advantage of "monitor inflation" in JVMs
170	<	* that we would otherwise need to emulate to avoid adding further
171	<	* per-task bookkeeping overhead. Note that bits 16-28 are
172	<	* currently unused. Also value 0x80000000 is available as spare
173	<	* completion value.
174	<	*/
175	<	volatile int status; // accessed directy by pool and workers
176	<
177	<	static final int COMPLETION_MASK      = 0xe0000000;
178	<	static final int NORMAL               = 0xe0000000; // == mask
179	<	static final int CANCELLED            = 0xc0000000;
180	<	static final int EXCEPTIONAL          = 0xa0000000;
181	<	static final int SIGNAL_MASK          = 0x0000ffff;
182	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
183	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
155	>
156	>	/*
157	>	* See the internal documentation of class ForkJoinPool for a
158	>	* general implementation overview.  ForkJoinTasks are mainly
159	>	* responsible for maintaining their "status" field amidst relays
160	>	* to methods in ForkJoinWorkerThread and ForkJoinPool. The
161	>	* methods of this class are more-or-less layered into (1) basic
162	>	* status maintenance (2) execution and awaiting completion (3)
163	>	* user-level methods that additionally report results. This is
164	>	* sometimes hard to see because this file orders exported methods
165	>	* in a way that flows well in javadocs. In particular, most
166	>	* join mechanics are in method quietlyJoin, below.
167	>	*/
168	>
169	>	/*
170	>	* The status field holds run control status bits packed into a
171	>	* single int to minimize footprint and to ensure atomicity (via
172	>	* CAS).  Status is initially zero, and takes on nonnegative
173	>	* values until completed, upon which status holds value
174	>	* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking
175	>	* waits by other threads have the SIGNAL bit set.  Completion of
176	>	* a stolen task with SIGNAL set awakens any waiters via
177	>	* notifyAll. Even though suboptimal for some purposes, we use
178	>	* basic builtin wait/notify to take advantage of "monitor
179	>	* inflation" in JVMs that we would otherwise need to emulate to
180	>	* avoid adding further per-task bookkeeping overhead.  We want
181	>	* these monitors to be "fat", i.e., not use biasing or thin-lock
182	>	* techniques, so use some odd coding idioms that tend to avoid
183	>	* them.
184	>	*/
185	>
186	>	/** The run status of this task */
187	>	volatile int status; // accessed directly by pool and workers
188	>
189	>	private static final int NORMAL      = -1;
190	>	private static final int CANCELLED   = -2;
191	>	private static final int EXCEPTIONAL = -3;
192	>	private static final int SIGNAL      =  1;
193
194		/**
195		* Table of exceptions thrown by tasks, to enable reporting by
196		* callers. Because exceptions are rare, we don't directly keep
197	<	* them with task objects, but instead us a weak ref table.  Note
197	>	* them with task objects, but instead use a weak ref table.  Note
198		* that cancellation exceptions don't appear in the table, but are
199		* instead recorded as status values.
200	<	* Todo: Use ConcurrentReferenceHashMap
200	>	* TODO: Use ConcurrentReferenceHashMap
201		*/
202		static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
203		Collections.synchronizedMap
204		(new WeakHashMap<ForkJoinTask<?>, Throwable>());
205
206	<	// within-package utilities
206	>	// Maintaining completion status
207
208		/**
209	<	* Get current worker thread, or null if not a worker thread
209	>	* Marks completion and wakes up threads waiting to join this task,
210	>	* also clearing signal request bits.
211	>	*
212	>	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
213		*/
214	<	static ForkJoinWorkerThread getWorker() {
215	<	Thread t = Thread.currentThread();
216	<	return ((t instanceof ForkJoinWorkerThread)?
217	<	(ForkJoinWorkerThread)t : null);
214	>	private void setCompletion(int completion) {
215	>	int s;
216	>	while ((s = status) >= 0) {
217	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) {
218	>	if (s != 0)
219	>	synchronized (this) { notifyAll(); }
220	>	break;
221	>	}
222	>	}
223		}
224
225		/**
226	<	* Get pool of current worker thread, or null if not a worker thread
226	>	* Records exception and sets exceptional completion.
227	>	*
228	>	* @return status on exit
229		*/
230	<	static ForkJoinPool getWorkerPool() {
231	<	Thread t = Thread.currentThread();
232	<	return ((t instanceof ForkJoinWorkerThread)?
153	<	((ForkJoinWorkerThread)t).pool : null);
154	<	}
155	<
156	<	final boolean casStatus(int cmp, int val) {
157	<	return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val);
230	>	private void setExceptionalCompletion(Throwable rex) {
231	>	exceptionMap.put(this, rex);
232	>	setCompletion(EXCEPTIONAL);
233		}
234
235		/**
236	<	* Workaround for not being able to rethrow unchecked exceptions.
236	>	* Blocks a worker thread until completion. Called only by
237	>	* pool. Currently unused -- pool-based waits use timeout
238	>	* version below.
239		*/
240	<	static void rethrowException(Throwable ex) {
241	<	if (ex != null)
242	<	_unsafe.throwException(ex);
240	>	final void internalAwaitDone() {
241	>	int s;         // the odd construction reduces lock bias effects
242	>	while ((s = status) >= 0) {
243	>	try {
244	>	synchronized (this) {
245	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
246	>	wait();
247	>	}
248	>	} catch (InterruptedException ie) {
249	>	cancelIfTerminating();
250	>	}
251	>	}
252		}
253
168	–	// Setting completion status
169	–
254		/**
255	<	* Mark completion and wake up threads waiting to join this task.
256	<	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
255	>	* Blocks a worker thread until completed or timed out.  Called
256	>	* only by pool.
257	>	*
258	>	* @return status on exit
259		*/
260	<	final void setCompletion(int completion) {
261	<	ForkJoinPool pool = getWorkerPool();
262	<	if (pool != null) {
263	<	int s; // Clear signal bits while setting completion status
264	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
265	<
266	<	if ((s & SIGNAL_MASK) != 0) {
267	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
268	<	pool.updateRunningCount(s);
269	<	synchronized(this) { notifyAll(); }
260	>	final int internalAwaitDone(long millis, int nanos) {
261	>	int s;
262	>	if ((s = status) >= 0) {
263	>	try {
264	>	synchronized (this) {
265	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL))
266	>	wait(millis, nanos);
267	>	}
268	>	} catch (InterruptedException ie) {
269	>	cancelIfTerminating();
270		}
271	+	s = status;
272		}
273	<	else
187	<	externallySetCompletion(completion);
273	>	return s;
274		}
275
276		/**
277	<	* Version of setCompletion for non-FJ threads.  Leaves signal
192	<	* bits for unblocked threads to adjust, and always notifies.
277	>	* Blocks a non-worker-thread until completion.
278		*/
279	<	private void externallySetCompletion(int completion) {
279	>	private void externalAwaitDone() {
280		int s;
281	<	do;while ((s = status) >= 0 &&
282	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
283	<	synchronized(this) { notifyAll(); }
281	>	while ((s = status) >= 0) {
282	>	synchronized (this) {
283	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) {
284	>	boolean interrupted = false;
285	>	while (status >= 0) {
286	>	try {
287	>	wait();
288	>	} catch (InterruptedException ie) {
289	>	interrupted = true;
290	>	}
291	>	}
292	>	if (interrupted)
293	>	Thread.currentThread().interrupt();
294	>	break;
295	>	}
296	>	}
297	>	}
298		}
299
300		/**
301	<	* Sets status to indicate normal completion
301	>	* Unless done, calls exec and records status if completed, but
302	>	* doesn't wait for completion otherwise. Primary execution method
303	>	* for ForkJoinWorkerThread.
304		*/
305	<	final void setNormalCompletion() {
306	<	// Try typical fast case -- single CAS, no signal, not already done.
307	<	// Manually expand casStatus to improve chances of inlining it
308	<	if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL))
309	<	setCompletion(NORMAL);
305	>	final void quietlyExec() {
306	>	try {
307	>	if (status < 0 || !exec())
308	>	return;
309	>	} catch (Throwable rex) {
310	>	setExceptionalCompletion(rex);
311	>	return;
312	>	}
313	>	setCompletion(NORMAL); // must be outside try block
314		}
315
316	<	// internal waiting and notification
316	>	// public methods
317
318		/**
319	<	* Performs the actual monitor wait for awaitDone
319	>	* Arranges to asynchronously execute this task.  While it is not
320	>	* necessarily enforced, it is a usage error to fork a task more
321	>	* than once unless it has completed and been reinitialized.
322	>	* Subsequent modifications to the state of this task or any data
323	>	* it operates on are not necessarily consistently observable by
324	>	* any thread other than the one executing it unless preceded by a
325	>	* call to {@link #join} or related methods, or a call to {@link
326	>	* #isDone} returning {@code true}.
327	>	*
328	>	* <p>This method may be invoked only from within {@code
329	>	* ForkJoinTask} computations (as may be determined using method
330	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
331	>	* result in exceptions or errors, possibly including {@code
332	>	* ClassCastException}.
333	>	*
334	>	* @return {@code this}, to simplify usage
335		*/
336	<	private void doAwaitDone() {
337	<	// Minimize lock bias and in/de-flation effects by maximizing
338	<	// chances of waiting inside sync
339	<	try {
220	<	while (status >= 0)
221	<	synchronized(this) { if (status >= 0) wait(); }
222	<	} catch (InterruptedException ie) {
223	<	onInterruptedWait();
224	<	}
336	>	public final ForkJoinTask<V> fork() {
337	>	((ForkJoinWorkerThread) Thread.currentThread())
338	>	.pushTask(this);
339	>	return this;
340		}
341
342		/**
343	<	* Performs the actual monitor wait for awaitDone
343	>	* Returns the result of the computation when it {@link #isDone is
344	>	* done}.  This method differs from {@link #get()} in that
345	>	* abnormal completion results in {@code RuntimeException} or
346	>	* {@code Error}, not {@code ExecutionException}, and that
347	>	* interrupts of the calling thread do <em>not</em> cause the
348	>	* method to abruptly return by throwing {@code
349	>	* InterruptedException}.
350	>	*
351	>	* @return the computed result
352		*/
353	<	private void doAwaitDone(long startTime, long nanos) {
354	<	synchronized(this) {
355	<	try {
356	<	while (status >= 0) {
357	<	long nt = nanos - System.nanoTime() - startTime;
358	<	if (nt <= 0)
236	<	break;
237	<	wait(nt / 1000000, (int)(nt % 1000000));
238	<	}
239	<	} catch (InterruptedException ie) {
240	<	onInterruptedWait();
241	<	}
242	<	}
353	>	public final V join() {
354	>	quietlyJoin();
355	>	Throwable ex;
356	>	if (status < NORMAL && (ex = getException()) != null)
357	>	UNSAFE.throwException(ex);
358	>	return getRawResult();
359		}
360
361	<	// Awaiting completion
361	>	/**
362	>	* Commences performing this task, awaits its completion if
363	>	* necessary, and returns its result, or throws an (unchecked)
364	>	* {@code RuntimeException} or {@code Error} if the underlying
365	>	* computation did so.
366	>	*
367	>	* @return the computed result
368	>	*/
369	>	public final V invoke() {
370	>	quietlyInvoke();
371	>	Throwable ex;
372	>	if (status < NORMAL && (ex = getException()) != null)
373	>	UNSAFE.throwException(ex);
374	>	return getRawResult();
375	>	}
376
377		/**
378	<	* Sets status to indicate there is joiner, then waits for join,
379	<	* surrounded with pool notifications.
380	<	* @return status upon exit
378	>	* Forks the given tasks, returning when {@code isDone} holds for
379	>	* each task or an (unchecked) exception is encountered, in which
380	>	* case the exception is rethrown. If more than one task
381	>	* encounters an exception, then this method throws any one of
382	>	* these exceptions. If any task encounters an exception, the
383	>	* other may be cancelled. However, the execution status of
384	>	* individual tasks is not guaranteed upon exceptional return. The
385	>	* status of each task may be obtained using {@link
386	>	* #getException()} and related methods to check if they have been
387	>	* cancelled, completed normally or exceptionally, or left
388	>	* unprocessed.
389	>	*
390	>	* <p>This method may be invoked only from within {@code
391	>	* ForkJoinPool} computations (as may be determined using method
392	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
393	>	* result in exceptions or errors, possibly including {@code
394	>	* ClassCastException}.
395	>	*
396	>	* @param t1 the first task
397	>	* @param t2 the second task
398	>	* @throws NullPointerException if any task is null
399		*/
400	<	final int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
401	<	ForkJoinPool pool = w == null? null : w.pool;
402	<	int s;
403	<	while ((s = status) >= 0) {
404	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
405	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
406	<	doAwaitDone();
407	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
408	<	adjustPoolCountsOnUnblock(pool);
409	<	break;
400	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
401	>	t2.fork();
402	>	t1.invoke();
403	>	t2.join();
404	>	}
405	>
406	>	/**
407	>	* Forks the given tasks, returning when {@code isDone} holds for
408	>	* each task or an (unchecked) exception is encountered, in which
409	>	* case the exception is rethrown. If more than one task
410	>	* encounters an exception, then this method throws any one of
411	>	* these exceptions. If any task encounters an exception, others
412	>	* may be cancelled. However, the execution status of individual
413	>	* tasks is not guaranteed upon exceptional return. The status of
414	>	* each task may be obtained using {@link #getException()} and
415	>	* related methods to check if they have been cancelled, completed
416	>	* normally or exceptionally, or left unprocessed.
417	>	*
418	>	* <p>This method may be invoked only from within {@code
419	>	* ForkJoinPool} computations (as may be determined using method
420	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
421	>	* result in exceptions or errors, possibly including {@code
422	>	* ClassCastException}.
423	>	*
424	>	* @param tasks the tasks
425	>	* @throws NullPointerException if any task is null
426	>	*/
427	>	public static void invokeAll(ForkJoinTask<?>... tasks) {
428	>	Throwable ex = null;
429	>	int last = tasks.length - 1;
430	>	for (int i = last; i >= 0; --i) {
431	>	ForkJoinTask<?> t = tasks[i];
432	>	if (t == null) {
433	>	if (ex == null)
434	>	ex = new NullPointerException();
435	>	}
436	>	else if (i != 0)
437	>	t.fork();
438	>	else {
439	>	t.quietlyInvoke();
440	>	if (ex == null && t.status < NORMAL)
441	>	ex = t.getException();
442		}
443		}
444	<	return s;
444	>	for (int i = 1; i <= last; ++i) {
445	>	ForkJoinTask<?> t = tasks[i];
446	>	if (t != null) {
447	>	if (ex != null)
448	>	t.cancel(false);
449	>	else {
450	>	t.quietlyJoin();
451	>	if (ex == null && t.status < NORMAL)
452	>	ex = t.getException();
453	>	}
454	>	}
455	>	}
456	>	if (ex != null)
457	>	UNSAFE.throwException(ex);
458		}
459
460		/**
461	<	* Timed version of awaitDone
462	<	* @return status upon exit
461	>	* Forks all tasks in the specified collection, returning when
462	>	* {@code isDone} holds for each task or an (unchecked) exception
463	>	* is encountered, in which case the exception is rethrown. If
464	>	* more than one task encounters an exception, then this method
465	>	* throws any one of these exceptions. If any task encounters an
466	>	* exception, others may be cancelled. However, the execution
467	>	* status of individual tasks is not guaranteed upon exceptional
468	>	* return. The status of each task may be obtained using {@link
469	>	* #getException()} and related methods to check if they have been
470	>	* cancelled, completed normally or exceptionally, or left
471	>	* unprocessed.
472	>	*
473	>	* <p>This method may be invoked only from within {@code
474	>	* ForkJoinPool} computations (as may be determined using method
475	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
476	>	* result in exceptions or errors, possibly including {@code
477	>	* ClassCastException}.
478	>	*
479	>	* @param tasks the collection of tasks
480	>	* @return the tasks argument, to simplify usage
481	>	* @throws NullPointerException if tasks or any element are null
482		*/
483	<	final int awaitDone(ForkJoinWorkerThread w, long nanos) {
484	<	ForkJoinPool pool = w == null? null : w.pool;
485	<	int s;
486	<	while ((s = status) >= 0) {
487	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
488	<	long startTime = System.nanoTime();
489	<	if (pool == null || !pool.preJoin(this, false))
490	<	doAwaitDone(startTime, nanos);
491	<	if ((s = status) >= 0) {
492	<	adjustPoolCountsOnCancelledWait(pool);
493	<	s = status;
483	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
484	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
485	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
486	>	return tasks;
487	>	}
488	>	@SuppressWarnings("unchecked")
489	>	List<? extends ForkJoinTask<?>> ts =
490	>	(List<? extends ForkJoinTask<?>>) tasks;
491	>	Throwable ex = null;
492	>	int last = ts.size() - 1;
493	>	for (int i = last; i >= 0; --i) {
494	>	ForkJoinTask<?> t = ts.get(i);
495	>	if (t == null) {
496	>	if (ex == null)
497	>	ex = new NullPointerException();
498	>	}
499	>	else if (i != 0)
500	>	t.fork();
501	>	else {
502	>	t.quietlyInvoke();
503	>	if (ex == null && t.status < NORMAL)
504	>	ex = t.getException();
505	>	}
506	>	}
507	>	for (int i = 1; i <= last; ++i) {
508	>	ForkJoinTask<?> t = ts.get(i);
509	>	if (t != null) {
510	>	if (ex != null)
511	>	t.cancel(false);
512	>	else {
513	>	t.quietlyJoin();
514	>	if (ex == null && t.status < NORMAL)
515	>	ex = t.getException();
516		}
283	–	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
284	–	adjustPoolCountsOnUnblock(pool);
285	–	break;
517		}
518		}
519	<	return s;
519	>	if (ex != null)
520	>	UNSAFE.throwException(ex);
521	>	return tasks;
522		}
523
524		/**
525	<	* Notify pool that thread is unblocked. Called by signalled
526	<	* threads when woken by non-FJ threads (which is atypical).
525	>	* Attempts to cancel execution of this task. This attempt will
526	>	* fail if the task has already completed or could not be
527	>	* cancelled for some other reason. If successful, and this task
528	>	* has not started when {@code cancel} is called, execution of
529	>	* this task is suppressed. After this method returns
530	>	* successfully, unless there is an intervening call to {@link
531	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
532	>	* {@link #isDone}, and {@code cancel} will return {@code true}
533	>	* and calls to {@link #join} and related methods will result in
534	>	* {@code CancellationException}.
535	>	*
536	>	* <p>This method may be overridden in subclasses, but if so, must
537	>	* still ensure that these properties hold. In particular, the
538	>	* {@code cancel} method itself must not throw exceptions.
539	>	*
540	>	* <p>This method is designed to be invoked by <em>other</em>
541	>	* tasks. To terminate the current task, you can just return or
542	>	* throw an unchecked exception from its computation method, or
543	>	* invoke {@link #completeExceptionally}.
544	>	*
545	>	* @param mayInterruptIfRunning this value has no effect in the
546	>	* default implementation because interrupts are not used to
547	>	* control cancellation.
548	>	*
549	>	* @return {@code true} if this task is now cancelled
550		*/
551	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
552	<	int s;
553	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
298	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
299	<	pool.updateRunningCount(s);
551	>	public boolean cancel(boolean mayInterruptIfRunning) {
552	>	setCompletion(CANCELLED);
553	>	return status == CANCELLED;
554		}
555
556		/**
557	<	* Notify pool to adjust counts on cancelled or timed out wait
557	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
558	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
559	>	* exceptions, but if it does anyway, we have no recourse during
560	>	* shutdown, so guard against this case.
561		*/
562	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
563	<	if (pool != null) {
564	<	int s;
565	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
309	<	if (casStatus(s, s - 1)) {
310	<	pool.updateRunningCount(1);
311	<	break;
312	<	}
313	<	}
562	>	final void cancelIgnoringExceptions() {
563	>	try {
564	>	cancel(false);
565	>	} catch (Throwable ignore) {
566		}
567		}
568
569	<	private void onInterruptedWait() {
569	>	/**
570	>	* Cancels if current thread is a terminating worker thread,
571	>	* ignoring any exceptions thrown by cancel.
572	>	*/
573	>	final void cancelIfTerminating() {
574		Thread t = Thread.currentThread();
575	<	if (t instanceof ForkJoinWorkerThread) {
576	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)t;
321	<	if (w.isTerminating())
322	<	cancelIgnoreExceptions();
323	<	}
324	<	else { // re-interrupt
575	>	if ((t instanceof ForkJoinWorkerThread) &&
576	>	((ForkJoinWorkerThread) t).isTerminating()) {
577		try {
578	<	t.interrupt();
579	<	} catch (SecurityException ignore) {
578	>	cancel(false);
579	>	} catch (Throwable ignore) {
580		}
581		}
582		}
583
584	<	// Recording and reporting exceptions
584	>	public final boolean isDone() {
585	>	return status < 0;
586	>	}
587
588	<	private void setDoneExceptionally(Throwable rex) {
589	<	exceptionMap.put(this, rex);
336	<	setCompletion(EXCEPTIONAL);
588	>	public final boolean isCancelled() {
589	>	return status == CANCELLED;
590		}
591
592		/**
593	<	* Throws the exception associated with status s;
594	<	* @throws the exception
593	>	* Returns {@code true} if this task threw an exception or was cancelled.
594	>	*
595	>	* @return {@code true} if this task threw an exception or was cancelled
596		*/
597	<	private void reportException(int s) {
598	<	if ((s &= COMPLETION_MASK) < NORMAL) {
345	<	if (s == CANCELLED)
346	<	throw new CancellationException();
347	<	else
348	<	rethrowException(exceptionMap.get(this));
349	<	}
597	>	public final boolean isCompletedAbnormally() {
598	>	return status < NORMAL;
599		}
600
601		/**
602	<	* Returns result or throws exception using j.u.c.Future conventions
603	<	* Only call when isDone known to be true.
602	>	* Returns {@code true} if this task completed without throwing an
603	>	* exception and was not cancelled.
604	>	*
605	>	* @return {@code true} if this task completed without throwing an
606	>	* exception and was not cancelled
607		*/
608	<	private V reportFutureResult()
609	<	throws ExecutionException, InterruptedException {
358	<	int s = status & COMPLETION_MASK;
359	<	if (s < NORMAL) {
360	<	Throwable ex;
361	<	if (s == CANCELLED)
362	<	throw new CancellationException();
363	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
364	<	throw new ExecutionException(ex);
365	<	if (Thread.interrupted())
366	<	throw new InterruptedException();
367	<	}
368	<	return getRawResult();
608	>	public final boolean isCompletedNormally() {
609	>	return status == NORMAL;
610		}
611
612		/**
613	<	* Returns result or throws exception using j.u.c.Future conventions
614	<	* with timeouts
613	>	* Returns the exception thrown by the base computation, or a
614	>	* {@code CancellationException} if cancelled, or {@code null} if
615	>	* none or if the method has not yet completed.
616	>	*
617	>	* @return the exception, or {@code null} if none
618		*/
619	<	private V reportTimedFutureResult()
620	<	throws InterruptedException, ExecutionException, TimeoutException {
621	<	Throwable ex;
622	<	int s = status & COMPLETION_MASK;
623	<	if (s == NORMAL)
380	<	return getRawResult();
381	<	if (s == CANCELLED)
382	<	throw new CancellationException();
383	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
384	<	throw new ExecutionException(ex);
385	<	if (Thread.interrupted())
386	<	throw new InterruptedException();
387	<	throw new TimeoutException();
388	<	}
389	<
390	<	// internal execution methods
391	<
392	<	/**
393	<	* Calls exec, recording completion, and rethrowing exception if
394	<	* encountered. Caller should normally check status before calling
395	<	* @return true if completed normally
396	<	*/
397	<	private boolean tryExec() {
398	<	try { // try block must contain only call to exec
399	<	if (!exec())
400	<	return false;
401	<	} catch (Throwable rex) {
402	<	setDoneExceptionally(rex);
403	<	rethrowException(rex);
404	<	return false; // not reached
405	<	}
406	<	setNormalCompletion();
407	<	return true;
619	>	public final Throwable getException() {
620	>	int s = status;
621	>	return ((s >= NORMAL)    ? null :
622	>	(s == CANCELLED) ? new CancellationException() :
623	>	exceptionMap.get(this));
624		}
625
626		/**
627	<	* Main execution method used by worker threads. Invokes
628	<	* base computation unless already complete
627	>	* Completes this task abnormally, and if not already aborted or
628	>	* cancelled, causes it to throw the given exception upon
629	>	* {@code join} and related operations. This method may be used
630	>	* to induce exceptions in asynchronous tasks, or to force
631	>	* completion of tasks that would not otherwise complete.  Its use
632	>	* in other situations is discouraged.  This method is
633	>	* overridable, but overridden versions must invoke {@code super}
634	>	* implementation to maintain guarantees.
635	>	*
636	>	* @param ex the exception to throw. If this exception is not a
637	>	* {@code RuntimeException} or {@code Error}, the actual exception
638	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
639		*/
640	<	final void quietlyExec() {
641	<	if (status >= 0) {
642	<	try {
643	<	if (!exec())
418	<	return;
419	<	} catch(Throwable rex) {
420	<	setDoneExceptionally(rex);
421	<	return;
422	<	}
423	<	setNormalCompletion();
424	<	}
640	>	public void completeExceptionally(Throwable ex) {
641	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
642	>	(ex instanceof Error) ? ex :
643	>	new RuntimeException(ex));
644		}
645
646		/**
647	<	* Calls exec, recording but not rethrowing exception
648	<	* Caller should normally check status before calling
649	<	* @return true if completed normally
647	>	* Completes this task, and if not already aborted or cancelled,
648	>	* returning the given value as the result of subsequent
649	>	* invocations of {@code join} and related operations. This method
650	>	* may be used to provide results for asynchronous tasks, or to
651	>	* provide alternative handling for tasks that would not otherwise
652	>	* complete normally. Its use in other situations is
653	>	* discouraged. This method is overridable, but overridden
654	>	* versions must invoke {@code super} implementation to maintain
655	>	* guarantees.
656	>	*
657	>	* @param value the result value for this task
658		*/
659	<	private boolean tryQuietlyInvoke() {
659	>	public void complete(V value) {
660		try {
661	<	if (!exec())
435	<	return false;
661	>	setRawResult(value);
662		} catch (Throwable rex) {
663	<	setDoneExceptionally(rex);
664	<	return false;
663	>	setExceptionalCompletion(rex);
664	>	return;
665		}
666	<	setNormalCompletion();
441	<	return true;
666	>	setCompletion(NORMAL);
667		}
668
669		/**
670	<	* Cancel, ignoring any exceptions it throws
670	>	* Waits if necessary for the computation to complete, and then
671	>	* retrieves its result.
672	>	*
673	>	* @return the computed result
674	>	* @throws CancellationException if the computation was cancelled
675	>	* @throws ExecutionException if the computation threw an
676	>	* exception
677	>	* @throws InterruptedException if the current thread is not a
678	>	* member of a ForkJoinPool and was interrupted while waiting
679		*/
680	<	final void cancelIgnoreExceptions() {
681	<	try {
682	<	cancel(false);
683	<	} catch(Throwable ignore) {
680	>	public final V get() throws InterruptedException, ExecutionException {
681	>	int s;
682	>	if (Thread.currentThread() instanceof ForkJoinWorkerThread) {
683	>	quietlyJoin();
684	>	s = status;
685		}
686	<	}
687	<
688	<	// public methods
689	<
690	<	/**
691	<	* Arranges to asynchronously execute this task.  While it is not
692	<	* necessarily enforced, it is a usage error to fork a task more
693	<	* than once unless it has completed and been reinitialized.  This
694	<	* method may be invoked only from within other ForkJoinTask
695	<	* computations. Attempts to invoke in other contexts result in
696	<	* exceptions or errors including ClassCastException.
697	<	*/
698	<	public final void fork() {
699	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
686	>	else {
687	>	while ((s = status) >= 0) {
688	>	synchronized (this) { // interruptible form of awaitDone
689	>	if (UNSAFE.compareAndSwapInt(this, statusOffset,
690	>	s, SIGNAL)) {
691	>	while (status >= 0)
692	>	wait();
693	>	}
694	>	}
695	>	}
696	>	}
697	>	if (s < NORMAL) {
698	>	Throwable ex;
699	>	if (s == CANCELLED)
700	>	throw new CancellationException();
701	>	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
702	>	throw new ExecutionException(ex);
703	>	}
704	>	return getRawResult();
705		}
706
707		/**
708	<	* Returns the result of the computation when it is ready.
709	<	* This method differs from <tt>get</tt> in that abnormal
471	<	* completion results in RuntimeExceptions or Errors, not
472	<	* ExecutionExceptions.
708	>	* Waits if necessary for at most the given time for the computation
709	>	* to complete, and then retrieves its result, if available.
710		*
711	+	* @param timeout the maximum time to wait
712	+	* @param unit the time unit of the timeout argument
713		* @return the computed result
714	+	* @throws CancellationException if the computation was cancelled
715	+	* @throws ExecutionException if the computation threw an
716	+	* exception
717	+	* @throws InterruptedException if the current thread is not a
718	+	* member of a ForkJoinPool and was interrupted while waiting
719	+	* @throws TimeoutException if the wait timed out
720		*/
476	–	public final V join() {
477	–	ForkJoinWorkerThread w = getWorker();
478	–	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
479	–	reportException(awaitDone(w, true));
480	–	return getRawResult();
481	–	}
482	–
483	–	public final V get() throws InterruptedException, ExecutionException {
484	–	ForkJoinWorkerThread w = getWorker();
485	–	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
486	–	awaitDone(w, true);
487	–	return reportFutureResult();
488	–	}
489	–
721		public final V get(long timeout, TimeUnit unit)
722		throws InterruptedException, ExecutionException, TimeoutException {
723	<	ForkJoinWorkerThread w = getWorker();
724	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
725	<	awaitDone(w, unit.toNanos(timeout));
726	<	return reportTimedFutureResult();
727	<	}
728	<
729	<	/**
730	<	* Possibly executes other tasks until this task is ready, then
731	<	* returns the result of the computation.  This method may be more
732	<	* efficient than <tt>join</tt>, but is only applicable when there
733	<	* are no potemtial dependencies between continuation of the
734	<	* current task and that of any other task that might be executed
735	<	* while helping. (This usually holds for pure divide-and-conquer
736	<	* tasks).
737	<	* @return the computed result
738	<	*/
739	<	public final V helpJoin() {
740	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
741	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
742	<	reportException(w.helpJoinTask(this));
723	>	long nanos = unit.toNanos(timeout);
724	>	if (status >= 0) {
725	>	Thread t = Thread.currentThread();
726	>	if (t instanceof ForkJoinWorkerThread) {
727	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
728	>	boolean completed = false; // timed variant of quietlyJoin
729	>	if (w.unpushTask(this)) {
730	>	try {
731	>	completed = exec();
732	>	} catch (Throwable rex) {
733	>	setExceptionalCompletion(rex);
734	>	}
735	>	}
736	>	if (completed)
737	>	setCompletion(NORMAL);
738	>	else if (status >= 0)
739	>	w.joinTask(this, true, nanos);
740	>	}
741	>	else if (Thread.interrupted())
742	>	throw new InterruptedException();
743	>	else {
744	>	long startTime = System.nanoTime();
745	>	int s; long nt;
746	>	while ((s = status) >= 0 &&
747	>	(nt = nanos - (System.nanoTime() - startTime)) > 0) {
748	>	if (UNSAFE.compareAndSwapInt(this, statusOffset, s,
749	>	SIGNAL)) {
750	>	long ms = nt / 1000000;
751	>	int ns = (int) (nt % 1000000);
752	>	synchronized (this) {
753	>	if (status >= 0)
754	>	wait(ms, ns); // exit on IE throw
755	>	}
756	>	}
757	>	}
758	>	}
759	>	}
760	>	int es = status;
761	>	if (es != NORMAL) {
762	>	Throwable ex;
763	>	if (es == CANCELLED)
764	>	throw new CancellationException();
765	>	if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
766	>	throw new ExecutionException(ex);
767	>	throw new TimeoutException();
768	>	}
769		return getRawResult();
770		}
771
772		/**
773	<	* Performs this task, awaits its completion if necessary, and
517	<	* return its result.
518	<	* @throws Throwable (a RuntimeException, Error, or unchecked
519	<	* exception) if the underlying computation did so.
520	<	* @return the computed result
521	<	*/
522	<	public final V invoke() {
523	<	if (status >= 0 && tryExec())
524	<	return getRawResult();
525	<	else
526	<	return join();
527	<	}
528	<
529	<	/**
530	<	* Joins this task, without returning its result or throwing an
773	>	* Joins this task, without returning its result or throwing its
774		* exception. This method may be useful when processing
775		* collections of tasks when some have been cancelled or otherwise
776		* known to have aborted.
777		*/
778		public final void quietlyJoin() {
779	<	if (status >= 0) {
780	<	ForkJoinWorkerThread w = getWorker();
781	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
782	<	awaitDone(w, true);
779	>	Thread t;
780	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
781	>	ForkJoinWorkerThread w = (ForkJoinWorkerThread) t;
782	>	if (status >= 0) {
783	>	if (w.unpushTask(this)) {
784	>	boolean completed;
785	>	try {
786	>	completed = exec();
787	>	} catch (Throwable rex) {
788	>	setExceptionalCompletion(rex);
789	>	return;
790	>	}
791	>	if (completed) {
792	>	setCompletion(NORMAL);
793	>	return;
794	>	}
795	>	}
796	>	w.joinTask(this, false, 0L);
797	>	}
798		}
799	+	else
800	+	externalAwaitDone();
801		}
802
803		/**
804	<	* Possibly executes other tasks until this task is ready.
804	>	* Commences performing this task and awaits its completion if
805	>	* necessary, without returning its result or throwing its
806	>	* exception.
807		*/
808	<	public final void quietlyHelpJoin() {
808	>	public final void quietlyInvoke() {
809		if (status >= 0) {
810	<	ForkJoinWorkerThread w =
811	<	(ForkJoinWorkerThread)(Thread.currentThread());
812	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
813	<	w.helpJoinTask(this);
810	>	boolean completed;
811	>	try {
812	>	completed = exec();
813	>	} catch (Throwable rex) {
814	>	setExceptionalCompletion(rex);
815	>	return;
816	>	}
817	>	if (completed)
818	>	setCompletion(NORMAL);
819	>	else
820	>	quietlyJoin();
821		}
822		}
823
824		/**
825	<	* Performs this task and awaits its completion if necessary,
826	<	* without returning its result or throwing an exception. This
827	<	* method may be useful when processing collections of tasks when
828	<	* some have been cancelled or otherwise known to have aborted.
825	>	* Possibly executes tasks until the pool hosting the current task
826	>	* {@link ForkJoinPool#isQuiescent is quiescent}. This method may
827	>	* be of use in designs in which many tasks are forked, but none
828	>	* are explicitly joined, instead executing them until all are
829	>	* processed.
830	>	*
831	>	* <p>This method may be invoked only from within {@code
832	>	* ForkJoinPool} computations (as may be determined using method
833	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
834	>	* result in exceptions or errors, possibly including {@code
835	>	* ClassCastException}.
836		*/
837	<	public final void quietlyInvoke() {
838	<	if (status >= 0 && !tryQuietlyInvoke())
839	<	quietlyJoin();
837	>	public static void helpQuiesce() {
838	>	((ForkJoinWorkerThread) Thread.currentThread())
839	>	.helpQuiescePool();
840		}
841
842		/**
843	<	* Returns true if the computation performed by this task has
844	<	* completed (or has been cancelled).
845	<	* @return true if this computation has completed
843	>	* Resets the internal bookkeeping state of this task, allowing a
844	>	* subsequent {@code fork}. This method allows repeated reuse of
845	>	* this task, but only if reuse occurs when this task has either
846	>	* never been forked, or has been forked, then completed and all
847	>	* outstanding joins of this task have also completed. Effects
848	>	* under any other usage conditions are not guaranteed.
849	>	* This method may be useful when executing
850	>	* pre-constructed trees of subtasks in loops.
851	>	*
852	>	* <p>Upon completion of this method, {@code isDone()} reports
853	>	* {@code false}, and {@code getException()} reports {@code
854	>	* null}. However, the value returned by {@code getRawResult} is
855	>	* unaffected. To clear this value, you can invoke {@code
856	>	* setRawResult(null)}.
857		*/
858	<	public final boolean isDone() {
859	<	return status < 0;
858	>	public void reinitialize() {
859	>	if (status == EXCEPTIONAL)
860	>	exceptionMap.remove(this);
861	>	status = 0;
862		}
863
864		/**
865	<	* Returns true if this task was cancelled.
866	<	* @return true if this task was cancelled
865	>	* Returns the pool hosting the current task execution, or null
866	>	* if this task is executing outside of any ForkJoinPool.
867	>	*
868	>	* @see #inForkJoinPool
869	>	* @return the pool, or {@code null} if none
870		*/
871	<	public final boolean isCancelled() {
872	<	return (status & COMPLETION_MASK) == CANCELLED;
871	>	public static ForkJoinPool getPool() {
872	>	Thread t = Thread.currentThread();
873	>	return (t instanceof ForkJoinWorkerThread) ?
874	>	((ForkJoinWorkerThread) t).pool : null;
875		}
876
877		/**
878	<	* Returns true if this task threw an exception or was cancelled
879	<	* @return true if this task threw an exception or was cancelled
878	>	* Returns {@code true} if the current thread is executing as a
879	>	* ForkJoinPool computation.
880	>	*
881	>	* @return {@code true} if the current thread is executing as a
882	>	* ForkJoinPool computation, or false otherwise
883		*/
884	<	public final boolean completedAbnormally() {
885	<	return (status & COMPLETION_MASK) < NORMAL;
884	>	public static boolean inForkJoinPool() {
885	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
886		}
887
888		/**
889	<	* Returns the exception thrown by the base computation, or a
890	<	* CancellationException if cancelled, or null if none or if the
891	<	* method has not yet completed.
892	<	* @return the exception, or null if none
889	>	* Tries to unschedule this task for execution. This method will
890	>	* typically succeed if this task is the most recently forked task
891	>	* by the current thread, and has not commenced executing in
892	>	* another thread.  This method may be useful when arranging
893	>	* alternative local processing of tasks that could have been, but
894	>	* were not, stolen.
895	>	*
896	>	* <p>This method may be invoked only from within {@code
897	>	* ForkJoinPool} computations (as may be determined using method
898	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
899	>	* result in exceptions or errors, possibly including {@code
900	>	* ClassCastException}.
901	>	*
902	>	* @return {@code true} if unforked
903		*/
904	<	public final Throwable getException() {
905	<	int s = status & COMPLETION_MASK;
906	<	if (s >= NORMAL)
600	<	return null;
601	<	if (s == CANCELLED)
602	<	return new CancellationException();
603	<	return exceptionMap.get(this);
904	>	public boolean tryUnfork() {
905	>	return ((ForkJoinWorkerThread) Thread.currentThread())
906	>	.unpushTask(this);
907		}
908
909		/**
910	<	* Asserts that the results of this task's computation will not be
911	<	* used. If a cancellation occurs before this task is processed,
912	<	* then its <tt>compute</tt> method will not be executed,
913	<	* <tt>isCancelled</tt> will report true, and <tt>join</tt> will
611	<	* result in a CancellationException being thrown. Otherwise, when
612	<	* cancellation races with completion, there are no guarantees
613	<	* about whether <tt>isCancelled</tt> will report true, whether
614	<	* <tt>join</tt> will return normally or via an exception, or
615	<	* whether these behaviors will remain consistent upon repeated
616	<	* invocation.
910	>	* Returns an estimate of the number of tasks that have been
911	>	* forked by the current worker thread but not yet executed. This
912	>	* value may be useful for heuristic decisions about whether to
913	>	* fork other tasks.
914		*
915	<	* <p>This method may be overridden in subclasses, but if so, must
916	<	* still ensure that these minimal properties hold. In particular,
917	<	* the cancel method itself must not throw exceptions.
915	>	* <p>This method may be invoked only from within {@code
916	>	* ForkJoinPool} computations (as may be determined using method
917	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
918	>	* result in exceptions or errors, possibly including {@code
919	>	* ClassCastException}.
920		*
921	<	* <p> This method is designed to be invoked by <em>other</em>
922	<	* tasks. To terminate the current task, you can just return or
923	<	* throw an unchecked exception from its computation method, or
924	<	* invoke <tt>completeExceptionally(someException)</tt>.
921	>	* @return the number of tasks
922	>	*/
923	>	public static int getQueuedTaskCount() {
924	>	return ((ForkJoinWorkerThread) Thread.currentThread())
925	>	.getQueueSize();
926	>	}
927	>
928	>	/**
929	>	* Returns an estimate of how many more locally queued tasks are
930	>	* held by the current worker thread than there are other worker
931	>	* threads that might steal them.  This value may be useful for
932	>	* heuristic decisions about whether to fork other tasks. In many
933	>	* usages of ForkJoinTasks, at steady state, each worker should
934	>	* aim to maintain a small constant surplus (for example, 3) of
935	>	* tasks, and to process computations locally if this threshold is
936	>	* exceeded.
937		*
938	<	* @param mayInterruptIfRunning this value is ignored in the
939	<	* default implementation because tasks are not in general
940	<	* cancelled via interruption.
938	>	* <p>This method may be invoked only from within {@code
939	>	* ForkJoinPool} computations (as may be determined using method
940	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
941	>	* result in exceptions or errors, possibly including {@code
942	>	* ClassCastException}.
943		*
944	<	* @return true if this task is now cancelled
944	>	* @return the surplus number of tasks, which may be negative
945		*/
946	<	public boolean cancel(boolean mayInterruptIfRunning) {
947	<	setCompletion(CANCELLED);
948	<	return (status & COMPLETION_MASK) == CANCELLED;
946	>	public static int getSurplusQueuedTaskCount() {
947	>	return ((ForkJoinWorkerThread) Thread.currentThread())
948	>	.getEstimatedSurplusTaskCount();
949		}
950
951	+	// Extension methods
952	+
953		/**
954	<	* Completes this task abnormally, and if not already aborted or
955	<	* cancelled, causes it to throw the given exception upon
956	<	* <tt>join</tt> and related operations. This method may be used
957	<	* to induce exceptions in asynchronous tasks, or to force
958	<	* completion of tasks that would not otherwise complete.  This
959	<	* method is overridable, but overridden versions must invoke
960	<	* <tt>super</tt> implementation to maintain guarantees.
646	<	* @param ex the exception to throw. If this exception is
647	<	* not a RuntimeException or Error, the actual exception thrown
648	<	* will be a RuntimeException with cause ex.
954	>	* Returns the result that would be returned by {@link #join}, even
955	>	* if this task completed abnormally, or {@code null} if this task
956	>	* is not known to have been completed.  This method is designed
957	>	* to aid debugging, as well as to support extensions. Its use in
958	>	* any other context is discouraged.
959	>	*
960	>	* @return the result, or {@code null} if not completed
961		*/
962	<	public void completeExceptionally(Throwable ex) {
651	<	setDoneExceptionally((ex instanceof RuntimeException) ||
652	<	(ex instanceof Error)? ex :
653	<	new RuntimeException(ex));
654	<	}
962	>	public abstract V getRawResult();
963
964		/**
965	<	* Completes this task, and if not already aborted or cancelled,
966	<	* returning a <tt>null</tt> result upon <tt>join</tt> and related
967	<	* operations. This method may be used to provide results for
660	<	* asynchronous tasks, or to provide alternative handling for
661	<	* tasks that would not otherwise complete normally.
965	>	* Forces the given value to be returned as a result.  This method
966	>	* is designed to support extensions, and should not in general be
967	>	* called otherwise.
968		*
969	<	* @param value the result value for this task.
969	>	* @param value the value
970		*/
971	<	public void complete(V value) {
666	<	try {
667	<	setRawResult(value);
668	<	} catch(Throwable rex) {
669	<	setDoneExceptionally(rex);
670	<	return;
671	<	}
672	<	setNormalCompletion();
673	<	}
971	>	protected abstract void setRawResult(V value);
972
973		/**
974	<	* Resets the internal bookkeeping state of this task, allowing a
975	<	* subsequent <tt>fork</tt>. This method allows repeated reuse of
976	<	* this task, but only if reuse occurs when this task has either
977	<	* never been forked, or has been forked, then completed and all
978	<	* outstanding joins of this task have also completed. Effects
979	<	* under any other usage conditions are not guaranteed, and are
980	<	* almost surely wrong. This method may be useful when executing
981	<	* pre-constructed trees of subtasks in loops.
974	>	* Immediately performs the base action of this task.  This method
975	>	* is designed to support extensions, and should not in general be
976	>	* called otherwise. The return value controls whether this task
977	>	* is considered to be done normally. It may return false in
978	>	* asynchronous actions that require explicit invocations of
979	>	* {@link #complete} to become joinable. It may also throw an
980	>	* (unchecked) exception to indicate abnormal exit.
981	>	*
982	>	* @return {@code true} if completed normally
983		*/
984	<	public void reinitialize() {
686	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
687	<	exceptionMap.remove(this);
688	<	status = 0;
689	<	}
984	>	protected abstract boolean exec();
985
986		/**
987	<	* Tries to unschedule this task for execution. This method will
988	<	* typically succeed if this task is the next task that would be
989	<	* executed by the current thread, and will typically fail (return
990	<	* false) otherwise. This method may be useful when arranging
991	<	* faster local processing of tasks that could have been, but were
992	<	* not, stolen.
993	<	* @return true if unforked
987	>	* Returns, but does not unschedule or execute, a task queued by
988	>	* the current thread but not yet executed, if one is immediately
989	>	* available. There is no guarantee that this task will actually
990	>	* be polled or executed next. Conversely, this method may return
991	>	* null even if a task exists but cannot be accessed without
992	>	* contention with other threads.  This method is designed
993	>	* primarily to support extensions, and is unlikely to be useful
994	>	* otherwise.
995	>	*
996	>	* <p>This method may be invoked only from within {@code
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}.
1001	>	*
1002	>	* @return the next task, or {@code null} if none are available
1003		*/
1004	<	public boolean tryUnfork() {
1005	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
1004	>	protected static ForkJoinTask<?> peekNextLocalTask() {
1005	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1006	>	.peekTask();
1007		}
1008
1009		/**
1010	<	* Forks both tasks, returning when <tt>isDone</tt> holds for both
1011	<	* of them or an exception is encountered. This method may be
1012	<	* invoked only from within other ForkJoinTask
1013	<	* computations. Attempts to invoke in other contexts result in
1014	<	* exceptions or errors including ClassCastException.
1015	<	* @param t1 one task
1016	<	* @param t2 the other task
1017	<	* @throws NullPointerException if t1 or t2 are null
1018	<	* @throws RuntimeException or Error if either task did so.
1010	>	* Unschedules and returns, without executing, the next task
1011	>	* queued by the current thread but not yet executed.  This method
1012	>	* is designed primarily to support extensions, and is unlikely to
1013	>	* be useful otherwise.
1014	>	*
1015	>	* <p>This method may be invoked only from within {@code
1016	>	* ForkJoinPool} computations (as may be determined using method
1017	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1018	>	* result in exceptions or errors, possibly including {@code
1019	>	* ClassCastException}.
1020	>	*
1021	>	* @return the next task, or {@code null} if none are available
1022		*/
1023	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
1024	<	t2.fork();
1025	<	t1.invoke();
718	<	t2.join();
1023	>	protected static ForkJoinTask<?> pollNextLocalTask() {
1024	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1025	>	.pollLocalTask();
1026		}
1027
1028		/**
1029	<	* Forks the given tasks, returning when <tt>isDone</tt> holds for
1030	<	* all of them. If any task encounters an exception, others may be
1031	<	* cancelled.  This method may be invoked only from within other
1032	<	* ForkJoinTask computations. Attempts to invoke in other contexts
1033	<	* result in exceptions or errors including ClassCastException.
1034	<	* @param tasks the array of tasks
1035	<	* @throws NullPointerException if tasks or any element are null.
1036	<	* @throws RuntimeException or Error if any task did so.
1029	>	* Unschedules and returns, without executing, the next task
1030	>	* queued by the current thread but not yet executed, if one is
1031	>	* available, or if not available, a task that was forked by some
1032	>	* other thread, if available. Availability may be transient, so a
1033	>	* {@code null} result does not necessarily imply quiescence
1034	>	* of the pool this task is operating in.  This method is designed
1035	>	* primarily to support extensions, and is unlikely to be useful
1036	>	* otherwise.
1037	>	*
1038	>	* <p>This method may be invoked only from within {@code
1039	>	* ForkJoinPool} computations (as may be determined using method
1040	>	* {@link #inForkJoinPool}).  Attempts to invoke in other contexts
1041	>	* result in exceptions or errors, possibly including {@code
1042	>	* ClassCastException}.
1043	>	*
1044	>	* @return a task, or {@code null} if none are available
1045		*/
1046	<	public static void invokeAll(ForkJoinTask<?>... tasks) {
1047	<	Throwable ex = null;
1048	<	int last = tasks.length - 1;
734	<	for (int i = last; i >= 0; --i) {
735	<	ForkJoinTask<?> t = tasks[i];
736	<	if (t == null) {
737	<	if (ex == null)
738	<	ex = new NullPointerException();
739	<	}
740	<	else if (i != 0)
741	<	t.fork();
742	<	else {
743	<	t.quietlyInvoke();
744	<	if (ex == null)
745	<	ex = t.getException();
746	<	}
747	<	}
748	<	for (int i = 1; i <= last; ++i) {
749	<	ForkJoinTask<?> t = tasks[i];
750	<	if (t != null) {
751	<	if (ex != null)
752	<	t.cancel(false);
753	<	else {
754	<	t.quietlyJoin();
755	<	if (ex == null)
756	<	ex = t.getException();
757	<	}
758	<	}
759	<	}
760	<	if (ex != null)
761	<	rethrowException(ex);
1046	>	protected static ForkJoinTask<?> pollTask() {
1047	>	return ((ForkJoinWorkerThread) Thread.currentThread())
1048	>	.pollTask();
1049		}
1050
1051		/**
1052	<	* Forks all tasks in the collection, returning when
1053	<	* <tt>isDone</tt> holds for all of them. If any task encounters
1054	<	* an exception, others may be cancelled.  This method may be
768	<	* invoked only from within other ForkJoinTask
769	<	* computations. Attempts to invoke in other contexts result in
770	<	* exceptions or errors including ClassCastException.
771	<	* @param tasks the collection of tasks
772	<	* @throws NullPointerException if tasks or any element are null.
773	<	* @throws RuntimeException or Error if any task did so.
1052	>	* Adaptor for Runnables. This implements RunnableFuture
1053	>	* to be compliant with AbstractExecutorService constraints
1054	>	* when used in ForkJoinPool.
1055		*/
1056	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
1057	<	if (!(tasks instanceof List)) {
1058	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
1059	<	return;
1060	<	}
1061	<	List<? extends ForkJoinTask<?>> ts =
1062	<	(List<? extends ForkJoinTask<?>>)tasks;
1063	<	Throwable ex = null;
1064	<	int last = ts.size() - 1;
784	<	for (int i = last; i >= 0; --i) {
785	<	ForkJoinTask<?> t = ts.get(i);
786	<	if (t == null) {
787	<	if (ex == null)
788	<	ex = new NullPointerException();
789	<	}
790	<	else if (i != 0)
791	<	t.fork();
792	<	else {
793	<	t.quietlyInvoke();
794	<	if (ex == null)
795	<	ex = t.getException();
796	<	}
1056	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1057	>	implements RunnableFuture<T> {
1058	>	final Runnable runnable;
1059	>	final T resultOnCompletion;
1060	>	T result;
1061	>	AdaptedRunnable(Runnable runnable, T result) {
1062	>	if (runnable == null) throw new NullPointerException();
1063	>	this.runnable = runnable;
1064	>	this.resultOnCompletion = result;
1065		}
1066	<	for (int i = 1; i <= last; ++i) {
1067	<	ForkJoinTask<?> t = ts.get(i);
1068	<	if (t != null) {
1069	<	if (ex != null)
1070	<	t.cancel(false);
1071	<	else {
804	<	t.quietlyJoin();
805	<	if (ex == null)
806	<	ex = t.getException();
807	<	}
808	<	}
1066	>	public T getRawResult() { return result; }
1067	>	public void setRawResult(T v) { result = v; }
1068	>	public boolean exec() {
1069	>	runnable.run();
1070	>	result = resultOnCompletion;
1071	>	return true;
1072		}
1073	<	if (ex != null)
1074	<	rethrowException(ex);
1073	>	public void run() { invoke(); }
1074	>	private static final long serialVersionUID = 5232453952276885070L;
1075		}
1076
1077		/**
1078	<	* Possibly executes tasks until the pool hosting the current task
816	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
817	<	* designs in which many tasks are forked, but none are explicitly
818	<	* joined, instead executing them until all are processed.
1078	>	* Adaptor for Callables
1079		*/
1080	<	public static void helpQuiesce() {
1081	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1082	<	helpQuiescePool();
1080	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1081	>	implements RunnableFuture<T> {
1082	>	final Callable<? extends T> callable;
1083	>	T result;
1084	>	AdaptedCallable(Callable<? extends T> callable) {
1085	>	if (callable == null) throw new NullPointerException();
1086	>	this.callable = callable;
1087	>	}
1088	>	public T getRawResult() { return result; }
1089	>	public void setRawResult(T v) { result = v; }
1090	>	public boolean exec() {
1091	>	try {
1092	>	result = callable.call();
1093	>	return true;
1094	>	} catch (Error err) {
1095	>	throw err;
1096	>	} catch (RuntimeException rex) {
1097	>	throw rex;
1098	>	} catch (Exception ex) {
1099	>	throw new RuntimeException(ex);
1100	>	}
1101	>	}
1102	>	public void run() { invoke(); }
1103	>	private static final long serialVersionUID = 2838392045355241008L;
1104		}
1105
1106		/**
1107	<	* Returns a estimate of how many more locally queued tasks are
1108	<	* held by the current worker thread than there are other worker
1109	<	* threads that might want to steal them.  This value may be
1110	<	* useful for heuristic decisions about whether to fork other
1111	<	* tasks. In many usages of ForkJoinTasks, at steady state, each
1112	<	* worker should aim to maintain a small constant surplus (for
832	<	* example, 3) of tasks, and to process computations locally if
833	<	* this threshold is exceeded.
834	<	* @return the surplus number of tasks, which may be negative
1107	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1108	>	* method of the given {@code Runnable} as its action, and returns
1109	>	* a null result upon {@link #join}.
1110	>	*
1111	>	* @param runnable the runnable action
1112	>	* @return the task
1113		*/
1114	<	public static int surplus() {
1115	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
838	<	.getEstimatedSurplusTaskCount();
1114	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1115	>	return new AdaptedRunnable<Void>(runnable, null);
1116		}
1117
841	–	// Extension kit
842	–
1118		/**
1119	<	* Returns the result that would be returned by <tt>join</tt>, or
1120	<	* null if this task is not known to have been completed.  This
1121	<	* method is designed to aid debugging, as well as to support
847	<	* extensions. Its use in any other context is discouraged.
1119	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1120	>	* method of the given {@code Runnable} as its action, and returns
1121	>	* the given result upon {@link #join}.
1122		*
1123	<	* @return the result, or null if not completed.
1123	>	* @param runnable the runnable action
1124	>	* @param result the result upon completion
1125	>	* @return the task
1126		*/
1127	<	public abstract V getRawResult();
1127	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1128	>	return new AdaptedRunnable<T>(runnable, result);
1129	>	}
1130
1131		/**
1132	<	* Forces the given value to be returned as a result.  This method
1133	<	* is designed to support extensions, and should not in general be
1134	<	* called otherwise.
1132	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1133	>	* method of the given {@code Callable} as its action, and returns
1134	>	* its result upon {@link #join}, translating any checked exceptions
1135	>	* encountered into {@code RuntimeException}.
1136		*
1137	<	* @param value the value
1138	<	*/
860	<	protected abstract void setRawResult(V value);
861	<
862	<	/**
863	<	* Immediately performs the base action of this task.  This method
864	<	* is designed to support extensions, and should not in general be
865	<	* called otherwise. The return value controls whether this task
866	<	* is considered to be done normally. It may return false in
867	<	* asynchronous actions that require explicit invocations of
868	<	* <tt>complete</tt> to become joinable. It may throw exceptions
869	<	* to indicate abnormal exit.
870	<	* @return true if completed normally
871	<	* @throws Error or RuntimeException if encountered during computation
1137	>	* @param callable the callable action
1138	>	* @return the task
1139		*/
1140	<	protected abstract boolean exec();
1140	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1141	>	return new AdaptedCallable<T>(callable);
1142	>	}
1143
1144		// Serialization support
1145
1146		private static final long serialVersionUID = -7721805057305804111L;
1147
1148		/**
1149	<	* Save the state to a stream.
1149	>	* Saves the state to a stream (that is, serializes it).
1150		*
1151		* @serialData the current run status and the exception thrown
1152	<	* during execution, or null if none.
1152	>	* during execution, or {@code null} if none
1153		* @param s the stream
1154		*/
1155		private void writeObject(java.io.ObjectOutputStream s)
#	Line 890 | Line 1159 | public abstract class ForkJoinTask<V> im
1159		}
1160
1161		/**
1162	<	* Reconstitute the instance from a stream.
1162	>	* Reconstitutes the instance from a stream (that is, deserializes it).
1163	>	*
1164		* @param s the stream
1165		*/
1166		private void readObject(java.io.ObjectInputStream s)
1167		throws java.io.IOException, ClassNotFoundException {
1168		s.defaultReadObject();
899	–	//        status &= ~INTERNAL_SIGNAL_MASK; //  todo: define policy
1169		Object ex = s.readObject();
1170		if (ex != null)
1171	<	setDoneExceptionally((Throwable)ex);
1171	>	setExceptionalCompletion((Throwable) ex);
1172		}
1173
1174	<	// Temporary Unsafe mechanics for preliminary release
1174	>	// Unsafe mechanics
1175
1176	<	static final Unsafe _unsafe;
1177	<	static final long statusOffset;
1176	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1177	>	private static final long statusOffset =
1178	>	objectFieldOffset("status", ForkJoinTask.class);
1179
1180	<	static {
1180	>	private static long objectFieldOffset(String field, Class<?> klazz) {
1181		try {
1182	<	if (ForkJoinTask.class.getClassLoader() != null) {
1183	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1184	<	f.setAccessible(true);
1185	<	_unsafe = (Unsafe)f.get(null);
1186	<	}
1187	<	else
1188	<	_unsafe = Unsafe.getUnsafe();
919	<	statusOffset = _unsafe.objectFieldOffset
920	<	(ForkJoinTask.class.getDeclaredField("status"));
921	<	} catch (Exception ex) { throw new Error(ex); }
1182	>	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1183	>	} catch (NoSuchFieldException e) {
1184	>	// Convert Exception to corresponding Error
1185	>	NoSuchFieldError error = new NoSuchFieldError(field);
1186	>	error.initCause(e);
1187	>	throw error;
1188	>	}
1189		}
1190
1191	+	/**
1192	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1193	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1194	+	* into a jdk.
1195	+	*
1196	+	* @return a sun.misc.Unsafe
1197	+	*/
1198	+	private static sun.misc.Unsafe getUnsafe() {
1199	+	try {
1200	+	return sun.misc.Unsafe.getUnsafe();
1201	+	} catch (SecurityException se) {
1202	+	try {
1203	+	return java.security.AccessController.doPrivileged
1204	+	(new java.security
1205	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1206	+	public sun.misc.Unsafe run() throws Exception {
1207	+	java.lang.reflect.Field f = sun.misc
1208	+	.Unsafe.class.getDeclaredField("theUnsafe");
1209	+	f.setAccessible(true);
1210	+	return (sun.misc.Unsafe) f.get(null);
1211	+	}});
1212	+	} catch (java.security.PrivilegedActionException e) {
1213	+	throw new RuntimeException("Could not initialize intrinsics",
1214	+	e.getCause());
1215	+	}
1216	+	}
1217	+	}
1218		}

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines