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 1.12 by jsr166, Wed Jul 22 01:36:51 2009 UTC vs.
Revision 1.103 by jsr166, Tue Oct 13 19:45:34 2015 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.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.List;
12	>	import java.util.RandomAccess;
13	>	import java.lang.ref.WeakReference;
14	>	import java.lang.ref.ReferenceQueue;
15	>	import java.util.concurrent.Callable;
16	>	import java.util.concurrent.CancellationException;
17	>	import java.util.concurrent.ExecutionException;
18	>	import java.util.concurrent.Future;
19	>	import java.util.concurrent.RejectedExecutionException;
20	>	import java.util.concurrent.RunnableFuture;
21	>	import java.util.concurrent.TimeUnit;
22	>	import java.util.concurrent.TimeoutException;
23	>	import java.util.concurrent.locks.ReentrantLock;
24	>	import java.lang.reflect.Constructor;
25
26		/**
27	<	* Abstract base class for tasks that run within a {@link
28	<	* ForkJoinPool}.  A ForkJoinTask is a thread-like entity that is much
27	>	* Abstract base class for tasks that run within a {@link ForkJoinPool}.
28	>	* A {@code ForkJoinTask} is a thread-like entity that is much
29		* lighter weight than a normal thread.  Huge numbers of tasks and
30		* subtasks may be hosted by a small number of actual threads in a
31		* ForkJoinPool, at the price of some usage limitations.
32		*
33	<	* <p> A "main" ForkJoinTask begins execution when submitted to a
34	<	* {@link ForkJoinPool}. Once started, it will usually in turn start
35	<	* other subtasks.  As indicated by the name of this class, many
36	<	* programs using ForkJoinTasks employ only methods {@code fork}
37	<	* and {@code join}, or derivatives such as
38	<	* {@code invokeAll}.  However, this class also provides a number
39	<	* of other methods that can come into play in advanced usages, as
40	<	* well as extension mechanics that allow support of new forms of
41	<	* fork/join processing.
33	>	* <p>A "main" {@code ForkJoinTask} begins execution when it is
34	>	* explicitly submitted to a {@link ForkJoinPool}, or, if not already
35	>	* engaged in a ForkJoin computation, commenced in the {@link
36	>	* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or
37	>	* related methods.  Once started, it will usually in turn start other
38	>	* subtasks.  As indicated by the name of this class, many programs
39	>	* using {@code ForkJoinTask} employ only methods {@link #fork} and
40	>	* {@link #join}, or derivatives such as {@link
41	>	* #invokeAll(ForkJoinTask...) invokeAll}.  However, this class also
42	>	* provides a number of other methods that can come into play in
43	>	* advanced usages, as well as extension mechanics that allow support
44	>	* of new forms of fork/join processing.
45	>	*
46	>	* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
47	>	* The efficiency of {@code ForkJoinTask}s stems from a set of
48	>	* restrictions (that are only partially statically enforceable)
49	>	* reflecting their main use as computational tasks calculating pure
50	>	* functions or operating on purely isolated objects.  The primary
51	>	* coordination mechanisms are {@link #fork}, that arranges
52	>	* asynchronous execution, and {@link #join}, that doesn't proceed
53	>	* until the task's result has been computed.  Computations should
54	>	* ideally avoid {@code synchronized} methods or blocks, and should
55	>	* minimize other blocking synchronization apart from joining other
56	>	* tasks or using synchronizers such as Phasers that are advertised to
57	>	* cooperate with fork/join scheduling. Subdividable tasks should also
58	>	* not perform blocking I/O, and should ideally access variables that
59	>	* are completely independent of those accessed by other running
60	>	* tasks. These guidelines are loosely enforced by not permitting
61	>	* checked exceptions such as {@code IOExceptions} to be
62	>	* thrown. However, computations may still encounter unchecked
63	>	* exceptions, that are rethrown to callers attempting to join
64	>	* them. These exceptions may additionally include {@link
65	>	* RejectedExecutionException} stemming from internal resource
66	>	* exhaustion, such as failure to allocate internal task
67	>	* queues. Rethrown exceptions behave in the same way as regular
68	>	* exceptions, but, when possible, contain stack traces (as displayed
69	>	* for example using {@code ex.printStackTrace()}) of both the thread
70	>	* that initiated the computation as well as the thread actually
71	>	* encountering the exception; minimally only the latter.
72		*
73	<	* <p>A ForkJoinTask is a lightweight form of {@link Future}.  The
74	<	* efficiency of ForkJoinTasks stems from a set of restrictions (that
75	<	* are only partially statically enforceable) reflecting their
76	<	* intended use as computational tasks calculating pure functions or
77	<	* operating on purely isolated objects.  The primary coordination
78	<	* mechanisms are {@link #fork}, that arranges asynchronous execution,
79	<	* and {@link #join}, that doesn't proceed until the task's result has
80	<	* been computed.  Computations should avoid {@code synchronized}
81	<	* methods or blocks, and should minimize other blocking
82	<	* synchronization apart from joining other tasks or using
83	<	* synchronizers such as Phasers that are advertised to cooperate with
84	<	* fork/join scheduling. Tasks should also not perform blocking IO,
85	<	* and should ideally access variables that are completely independent
45	<	* of those accessed by other running tasks. Minor breaches of these
46	<	* restrictions, for example using shared output streams, may be
47	<	* tolerable in practice, but frequent use may result in poor
48	<	* performance, and the potential to indefinitely stall if the number
49	<	* of threads not waiting for IO or other external synchronization
50	<	* becomes exhausted. This usage restriction is in part enforced by
51	<	* not permitting checked exceptions such as {@code IOExceptions}
52	<	* to be thrown. However, computations may still encounter unchecked
53	<	* exceptions, that are rethrown to callers attempting join
54	<	* them. These exceptions may additionally include
55	<	* RejectedExecutionExceptions stemming from internal resource
56	<	* exhaustion such as failure to allocate internal task queues.
73	>	* <p>It is possible to define and use ForkJoinTasks that may block,
74	>	* but doing do requires three further considerations: (1) Completion
75	>	* of few if any <em>other</em> tasks should be dependent on a task
76	>	* that blocks on external synchronization or I/O. Event-style async
77	>	* tasks that are never joined (for example, those subclassing {@link
78	>	* CountedCompleter}) often fall into this category.  (2) To minimize
79	>	* resource impact, tasks should be small; ideally performing only the
80	>	* (possibly) blocking action. (3) Unless the {@link
81	>	* ForkJoinPool.ManagedBlocker} API is used, or the number of possibly
82	>	* blocked tasks is known to be less than the pool's {@link
83	>	* ForkJoinPool#getParallelism} level, the pool cannot guarantee that
84	>	* enough threads will be available to ensure progress or good
85	>	* performance.
86		*
87		* <p>The primary method for awaiting completion and extracting
88		* results of a task is {@link #join}, but there are several variants:
89		* The {@link Future#get} methods support interruptible and/or timed
90		* waits for completion and report results using {@code Future}
91	<	* conventions. Method {@link #helpJoin} enables callers to actively
92	<	* execute other tasks while awaiting joins, which is sometimes more
93	<	* efficient but only applies when all subtasks are known to be
94	<	* strictly tree-structured. Method {@link #invoke} is semantically
66	<	* equivalent to {@code fork(); join()} but always attempts to
67	<	* begin execution in the current thread. The "<em>quiet</em>" forms
68	<	* of these methods do not extract results or report exceptions. These
91	>	* conventions. Method {@link #invoke} is semantically
92	>	* equivalent to {@code fork(); join()} but always attempts to begin
93	>	* execution in the current thread. The "<em>quiet</em>" forms of
94	>	* these methods do not extract results or report exceptions. These
95		* may be useful when a set of tasks are being executed, and you need
96		* to delay processing of results or exceptions until all complete.
97		* Method {@code invokeAll} (available in multiple versions)
98		* performs the most common form of parallel invocation: forking a set
99		* of tasks and joining them all.
100		*
101	<	* <p> The ForkJoinTask class is not usually directly subclassed.
101	>	* <p>In the most typical usages, a fork-join pair act like a call
102	>	* (fork) and return (join) from a parallel recursive function. As is
103	>	* the case with other forms of recursive calls, returns (joins)
104	>	* should be performed innermost-first. For example, {@code a.fork();
105	>	* b.fork(); b.join(); a.join();} is likely to be substantially more
106	>	* efficient than joining {@code a} before {@code b}.
107	>	*
108	>	* <p>The execution status of tasks may be queried at several levels
109	>	* of detail: {@link #isDone} is true if a task completed in any way
110	>	* (including the case where a task was cancelled without executing);
111	>	* {@link #isCompletedNormally} is true if a task completed without
112	>	* cancellation or encountering an exception; {@link #isCancelled} is
113	>	* true if the task was cancelled (in which case {@link #getException}
114	>	* returns a {@link java.util.concurrent.CancellationException}); and
115	>	* {@link #isCompletedAbnormally} is true if a task was either
116	>	* cancelled or encountered an exception, in which case {@link
117	>	* #getException} will return either the encountered exception or
118	>	* {@link java.util.concurrent.CancellationException}.
119	>	*
120	>	* <p>The ForkJoinTask class is not usually directly subclassed.
121		* Instead, you subclass one of the abstract classes that support a
122	<	* particular style of fork/join processing.  Normally, a concrete
123	<	* ForkJoinTask subclass declares fields comprising its parameters,
124	<	* established in a constructor, and then defines a {@code compute}
125	<	* method that somehow uses the control methods supplied by this base
126	<	* class. While these methods have {@code public} access (to allow
127	<	* instances of different task subclasses to call each others
128	<	* methods), some of them may only be called from within other
129	<	* ForkJoinTasks. Attempts to invoke them in other contexts result in
130	<	* exceptions or errors possibly including ClassCastException.
122	>	* particular style of fork/join processing, typically {@link
123	>	* RecursiveAction} for most computations that do not return results,
124	>	* {@link RecursiveTask} for those that do, and {@link
125	>	* CountedCompleter} for those in which completed actions trigger
126	>	* other actions.  Normally, a concrete ForkJoinTask subclass declares
127	>	* fields comprising its parameters, established in a constructor, and
128	>	* then defines a {@code compute} method that somehow uses the control
129	>	* methods supplied by this base class.
130	>	*
131	>	* <p>Method {@link #join} and its variants are appropriate for use
132	>	* only when completion dependencies are acyclic; that is, the
133	>	* parallel computation can be described as a directed acyclic graph
134	>	* (DAG). Otherwise, executions may encounter a form of deadlock as
135	>	* tasks cyclically wait for each other.  However, this framework
136	>	* supports other methods and techniques (for example the use of
137	>	* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
138	>	* may be of use in constructing custom subclasses for problems that
139	>	* are not statically structured as DAGs. To support such usages a
140	>	* ForkJoinTask may be atomically <em>tagged</em> with a {@code short}
141	>	* value using {@link #setForkJoinTaskTag} or {@link
142	>	* #compareAndSetForkJoinTaskTag} and checked using {@link
143	>	* #getForkJoinTaskTag}. The ForkJoinTask implementation does not use
144	>	* these {@code protected} methods or tags for any purpose, but they
145	>	* may be of use in the construction of specialized subclasses.  For
146	>	* example, parallel graph traversals can use the supplied methods to
147	>	* avoid revisiting nodes/tasks that have already been processed.
148	>	* (Method names for tagging are bulky in part to encourage definition
149	>	* of methods that reflect their usage patterns.)
150		*
151	<	* <p>Most base support methods are {@code final} because their
152	<	* implementations are intrinsically tied to the underlying
153	<	* lightweight task scheduling framework, and so cannot be overridden.
154	<	* Developers creating new basic styles of fork/join processing should
155	<	* minimally implement {@code protected} methods
156	<	* {@code exec}, {@code setRawResult}, and
157	<	* {@code getRawResult}, while also introducing an abstract
158	<	* computational method that can be implemented in its subclasses,
159	<	* possibly relying on other {@code protected} methods provided
96	<	* by this class.
151	>	* <p>Most base support methods are {@code final}, to prevent
152	>	* overriding of implementations that are intrinsically tied to the
153	>	* underlying lightweight task scheduling framework.  Developers
154	>	* creating new basic styles of fork/join processing should minimally
155	>	* implement {@code protected} methods {@link #exec}, {@link
156	>	* #setRawResult}, and {@link #getRawResult}, while also introducing
157	>	* an abstract computational method that can be implemented in its
158	>	* subclasses, possibly relying on other {@code protected} methods
159	>	* provided by this class.
160		*
161		* <p>ForkJoinTasks should perform relatively small amounts of
162	<	* computations, otherwise splitting into smaller tasks. As a very
163	<	* rough rule of thumb, a task should perform more than 100 and less
164	<	* than 10000 basic computational steps. If tasks are too big, then
165	<	* parallelism cannot improve throughput. If too small, then memory
166	<	* and internal task maintenance overhead may overwhelm processing.
162	>	* computation. Large tasks should be split into smaller subtasks,
163	>	* usually via recursive decomposition. As a very rough rule of thumb,
164	>	* a task should perform more than 100 and less than 10000 basic
165	>	* computational steps, and should avoid indefinite looping. If tasks
166	>	* are too big, then parallelism cannot improve throughput. If too
167	>	* small, then memory and internal task maintenance overhead may
168	>	* overwhelm processing.
169		*
170	<	* <p>ForkJoinTasks are {@code Serializable}, which enables them
171	<	* to be used in extensions such as remote execution frameworks. It is
172	<	* in general sensible to serialize tasks only before or after, but
173	<	* not during execution. Serialization is not relied on during
174	<	* execution itself.
170	>	* <p>This class provides {@code adapt} methods for {@link Runnable}
171	>	* and {@link Callable}, that may be of use when mixing execution of
172	>	* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
173	>	* of this form, consider using a pool constructed in <em>asyncMode</em>.
174	>	*
175	>	* <p>ForkJoinTasks are {@code Serializable}, which enables them to be
176	>	* used in extensions such as remote execution frameworks. It is
177	>	* sensible to serialize tasks only before or after, but not during,
178	>	* execution. Serialization is not relied on during execution itself.
179		*
180		* @since 1.7
181		* @author Doug Lea
182		*/
183		public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
184
185	<	/**
186	<	* Run control status bits packed into a single int to minimize
187	<	* footprint and to ensure atomicity (via CAS).  Status is
188	<	* initially zero, and takes on nonnegative values until
189	<	* completed, upon which status holds COMPLETED. CANCELLED, or
190	<	* EXCEPTIONAL, which use the top 3 bits.  Tasks undergoing
191	<	* blocking waits by other threads have SIGNAL_MASK bits set --
192	<	* bit 15 for external (nonFJ) waits, and the rest a count of
193	<	* waiting FJ threads.  (This representation relies on
194	<	* ForkJoinPool max thread limits). Completion of a stolen task
195	<	* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even
196	<	* though suboptimal for some purposes, we use basic builtin
197	<	* wait/notify to take advantage of "monitor inflation" in JVMs
198	<	* that we would otherwise need to emulate to avoid adding further
199	<	* per-task bookkeeping overhead. Note that bits 16-28 are
200	<	* currently unused. Also value 0x80000000 is available as spare
201	<	* completion value.
185	>	/*
186	>	* See the internal documentation of class ForkJoinPool for a
187	>	* general implementation overview.  ForkJoinTasks are mainly
188	>	* responsible for maintaining their "status" field amidst relays
189	>	* to methods in ForkJoinWorkerThread and ForkJoinPool.
190	>	*
191	>	* The methods of this class are more-or-less layered into
192	>	* (1) basic status maintenance
193	>	* (2) execution and awaiting completion
194	>	* (3) user-level methods that additionally report results.
195	>	* This is sometimes hard to see because this file orders exported
196	>	* methods in a way that flows well in javadocs.
197	>	*/
198	>
199	>	/*
200	>	* The status field holds run control status bits packed into a
201	>	* single int to minimize footprint and to ensure atomicity (via
202	>	* CAS).  Status is initially zero, and takes on nonnegative
203	>	* values until completed, upon which status (anded with
204	>	* DONE_MASK) holds value NORMAL, CANCELLED, or EXCEPTIONAL. Tasks
205	>	* undergoing blocking waits by other threads have the SIGNAL bit
206	>	* set.  Completion of a stolen task with SIGNAL set awakens any
207	>	* waiters via notifyAll. Even though suboptimal for some
208	>	* purposes, we use basic builtin wait/notify to take advantage of
209	>	* "monitor inflation" in JVMs that we would otherwise need to
210	>	* emulate to avoid adding further per-task bookkeeping overhead.
211	>	* We want these monitors to be "fat", i.e., not use biasing or
212	>	* thin-lock techniques, so use some odd coding idioms that tend
213	>	* to avoid them, mainly by arranging that every synchronized
214	>	* block performs a wait, notifyAll or both.
215	>	*
216	>	* These control bits occupy only (some of) the upper half (16
217	>	* bits) of status field. The lower bits are used for user-defined
218	>	* tags.
219		*/
134	–	volatile int status; // accessed directly by pool and workers
220
221	<	static final int COMPLETION_MASK      = 0xe0000000;
222	<	static final int NORMAL               = 0xe0000000; // == mask
223	<	static final int CANCELLED            = 0xc0000000;
224	<	static final int EXCEPTIONAL          = 0xa0000000;
225	<	static final int SIGNAL_MASK          = 0x0000ffff;
226	<	static final int INTERNAL_SIGNAL_MASK = 0x00007fff;
227	<	static final int EXTERNAL_SIGNAL      = 0x00008000; // top bit of low word
221	>	/** The run status of this task */
222	>	volatile int status; // accessed directly by pool and workers
223	>	static final int DONE_MASK   = 0xf0000000;  // mask out non-completion bits
224	>	static final int NORMAL      = 0xf0000000;  // must be negative
225	>	static final int CANCELLED   = 0xc0000000;  // must be < NORMAL
226	>	static final int EXCEPTIONAL = 0x80000000;  // must be < CANCELLED
227	>	static final int SIGNAL      = 0x00010000;  // must be >= 1 << 16
228	>	static final int SMASK       = 0x0000ffff;  // short bits for tags
229
230		/**
231	<	* Table of exceptions thrown by tasks, to enable reporting by
232	<	* callers. Because exceptions are rare, we don't directly keep
233	<	* them with task objects, but instead use a weak ref table.  Note
234	<	* that cancellation exceptions don't appear in the table, but are
235	<	* instead recorded as status values.
150	<	* TODO: Use ConcurrentReferenceHashMap
231	>	* Marks completion and wakes up threads waiting to join this
232	>	* task.
233	>	*
234	>	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
235	>	* @return completion status on exit
236		*/
237	<	static final Map<ForkJoinTask<?>, Throwable> exceptionMap =
238	<	Collections.synchronizedMap
239	<	(new WeakHashMap<ForkJoinTask<?>, Throwable>());
237	>	private int setCompletion(int completion) {
238	>	for (int s;;) {
239	>	if ((s = status) < 0)
240	>	return s;
241	>	if (U.compareAndSwapInt(this, STATUS, s, s | completion)) {
242	>	if ((s >>> 16) != 0)
243	>	synchronized (this) { notifyAll(); }
244	>	return completion;
245	>	}
246	>	}
247	>	}
248
249	<	// within-package utilities
249	>	/**
250	>	* Primary execution method for stolen tasks. Unless done, calls
251	>	* exec and records status if completed, but doesn't wait for
252	>	* completion otherwise.
253	>	*
254	>	* @return status on exit from this method
255	>	*/
256	>	final int doExec() {
257	>	int s; boolean completed;
258	>	if ((s = status) >= 0) {
259	>	try {
260	>	completed = exec();
261	>	} catch (Throwable rex) {
262	>	return setExceptionalCompletion(rex);
263	>	}
264	>	if (completed)
265	>	s = setCompletion(NORMAL);
266	>	}
267	>	return s;
268	>	}
269
270		/**
271	<	* Gets current worker thread, or null if not a worker thread.
271	>	* Tries to set SIGNAL status unless already completed. Used by
272	>	* ForkJoinPool. Other variants are directly incorporated into
273	>	* externalAwaitDone etc.
274	>	*
275	>	* @return true if successful
276		*/
277	<	static ForkJoinWorkerThread getWorker() {
278	<	Thread t = Thread.currentThread();
279	<	return ((t instanceof ForkJoinWorkerThread)?
164	<	(ForkJoinWorkerThread)t : null);
277	>	final boolean trySetSignal() {
278	>	int s = status;
279	>	return s >= 0 && U.compareAndSwapInt(this, STATUS, s, s | SIGNAL);
280		}
281
282	<	final boolean casStatus(int cmp, int val) {
283	<	return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val);
282	>	/**
283	>	* Blocks a non-worker-thread until completion.
284	>	* @return status upon completion
285	>	*/
286	>	private int externalAwaitDone() {
287	>	int s;
288	>	ForkJoinPool.externalHelpJoin(this);
289	>	boolean interrupted = false;
290	>	while ((s = status) >= 0) {
291	>	if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
292	>	synchronized (this) {
293	>	if (status >= 0) {
294	>	try {
295	>	wait();
296	>	} catch (InterruptedException ie) {
297	>	interrupted = true;
298	>	}
299	>	}
300	>	else
301	>	notifyAll();
302	>	}
303	>	}
304	>	}
305	>	if (interrupted)
306	>	Thread.currentThread().interrupt();
307	>	return s;
308		}
309
310		/**
311	<	* Workaround for not being able to rethrow unchecked exceptions.
311	>	* Blocks a non-worker-thread until completion or interruption.
312		*/
313	<	static void rethrowException(Throwable ex) {
314	<	if (ex != null)
315	<	UNSAFE.throwException(ex);
313	>	private int externalInterruptibleAwaitDone() throws InterruptedException {
314	>	int s;
315	>	if (Thread.interrupted())
316	>	throw new InterruptedException();
317	>	ForkJoinPool.externalHelpJoin(this);
318	>	while ((s = status) >= 0) {
319	>	if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
320	>	synchronized (this) {
321	>	if (status >= 0)
322	>	wait();
323	>	else
324	>	notifyAll();
325	>	}
326	>	}
327	>	}
328	>	return s;
329		}
330
179	–	// Setting completion status
331
332		/**
333	<	* Marks completion and wakes up threads waiting to join this task.
333	>	* Implementation for join, get, quietlyJoin. Directly handles
334	>	* only cases of already-completed, external wait, and
335	>	* unfork+exec.  Others are relayed to ForkJoinPool.awaitJoin.
336		*
337	<	* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL
337	>	* @return status upon completion
338		*/
339	<	final void setCompletion(int completion) {
340	<	ForkJoinPool pool = getPool();
341	<	if (pool != null) {
342	<	int s; // Clear signal bits while setting completion status
343	<	do;while ((s = status) >= 0 && !casStatus(s, completion));
344	<
345	<	if ((s & SIGNAL_MASK) != 0) {
346	<	if ((s &= INTERNAL_SIGNAL_MASK) != 0)
194	<	pool.updateRunningCount(s);
195	<	synchronized(this) { notifyAll(); }
196	<	}
197	<	}
198	<	else
199	<	externallySetCompletion(completion);
339	>	private int doJoin() {
340	>	int s; Thread t; ForkJoinWorkerThread wt; ForkJoinPool.WorkQueue w;
341	>	return (s = status) < 0 ? s :
342	>	((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
343	>	(w = (wt = (ForkJoinWorkerThread)t).workQueue).
344	>	tryUnpush(this) && (s = doExec()) < 0 ? s :
345	>	wt.pool.awaitJoin(w, this) :
346	>	externalAwaitDone();
347		}
348
349		/**
350	<	* Version of setCompletion for non-FJ threads.  Leaves signal
351	<	* bits for unblocked threads to adjust, and always notifies.
350	>	* Implementation for invoke, quietlyInvoke.
351	>	*
352	>	* @return status upon completion
353		*/
354	<	private void externallySetCompletion(int completion) {
355	<	int s;
356	<	do;while ((s = status) >= 0 &&
357	<	!casStatus(s, (s & SIGNAL_MASK) | completion));
358	<	synchronized(this) { notifyAll(); }
354	>	private int doInvoke() {
355	>	int s; Thread t; ForkJoinWorkerThread wt;
356	>	return (s = doExec()) < 0 ? s :
357	>	((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
358	>	(wt = (ForkJoinWorkerThread)t).pool.awaitJoin(wt.workQueue, this) :
359	>	externalAwaitDone();
360		}
361
362	+	// Exception table support
363	+
364		/**
365	<	* Sets status to indicate normal completion
365	>	* Table of exceptions thrown by tasks, to enable reporting by
366	>	* callers. Because exceptions are rare, we don't directly keep
367	>	* them with task objects, but instead use a weak ref table.  Note
368	>	* that cancellation exceptions don't appear in the table, but are
369	>	* instead recorded as status values.
370	>	*
371	>	* Note: These statics are initialized below in static block.
372		*/
373	<	final void setNormalCompletion() {
374	<	// Try typical fast case -- single CAS, no signal, not already done.
375	<	// Manually expand casStatus to improve chances of inlining it
219	<	if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL))
220	<	setCompletion(NORMAL);
221	<	}
373	>	private static final ExceptionNode[] exceptionTable;
374	>	private static final ReentrantLock exceptionTableLock;
375	>	private static final ReferenceQueue<Object> exceptionTableRefQueue;
376
377	<	// internal waiting and notification
377	>	/**
378	>	* Fixed capacity for exceptionTable.
379	>	*/
380	>	private static final int EXCEPTION_MAP_CAPACITY = 32;
381
382		/**
383	<	* Performs the actual monitor wait for awaitDone
383	>	* Key-value nodes for exception table.  The chained hash table
384	>	* uses identity comparisons, full locking, and weak references
385	>	* for keys. The table has a fixed capacity because it only
386	>	* maintains task exceptions long enough for joiners to access
387	>	* them, so should never become very large for sustained
388	>	* periods. However, since we do not know when the last joiner
389	>	* completes, we must use weak references and expunge them. We do
390	>	* so on each operation (hence full locking). Also, some thread in
391	>	* any ForkJoinPool will call helpExpungeStaleExceptions when its
392	>	* pool becomes isQuiescent.
393		*/
394	<	private void doAwaitDone() {
395	<	// Minimize lock bias and in/de-flation effects by maximizing
396	<	// chances of waiting inside sync
397	<	try {
398	<	while (status >= 0)
399	<	synchronized(this) { if (status >= 0) wait(); }
400	<	} catch (InterruptedException ie) {
401	<	onInterruptedWait();
394	>	static final class ExceptionNode extends WeakReference<ForkJoinTask<?>> {
395	>	final Throwable ex;
396	>	ExceptionNode next;
397	>	final long thrower;  // use id not ref to avoid weak cycles
398	>	final int hashCode;  // store task hashCode before weak ref disappears
399	>	ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) {
400	>	super(task, exceptionTableRefQueue);
401	>	this.ex = ex;
402	>	this.next = next;
403	>	this.thrower = Thread.currentThread().getId();
404	>	this.hashCode = System.identityHashCode(task);
405		}
406		}
407
408		/**
409	<	* Performs the actual monitor wait for awaitDone
409	>	* Records exception and sets status.
410	>	*
411	>	* @return status on exit
412		*/
413	<	private void doAwaitDone(long startTime, long nanos) {
414	<	synchronized(this) {
413	>	final int recordExceptionalCompletion(Throwable ex) {
414	>	int s;
415	>	if ((s = status) >= 0) {
416	>	int h = System.identityHashCode(this);
417	>	final ReentrantLock lock = exceptionTableLock;
418	>	lock.lock();
419		try {
420	<	while (status >= 0) {
421	<	long nt = nanos - System.nanoTime() - startTime;
422	<	if (nt <= 0)
420	>	expungeStaleExceptions();
421	>	ExceptionNode[] t = exceptionTable;
422	>	int i = h & (t.length - 1);
423	>	for (ExceptionNode e = t[i]; ; e = e.next) {
424	>	if (e == null) {
425	>	t[i] = new ExceptionNode(this, ex, t[i]);
426	>	break;
427	>	}
428	>	if (e.get() == this) // already present
429		break;
249	–	wait(nt / 1000000, (int)(nt % 1000000));
430		}
431	<	} catch (InterruptedException ie) {
432	<	onInterruptedWait();
431	>	} finally {
432	>	lock.unlock();
433		}
434	+	s = setCompletion(EXCEPTIONAL);
435		}
436	+	return s;
437		}
438
257	–	// Awaiting completion
258	–
439		/**
440	<	* Sets status to indicate there is joiner, then waits for join,
261	<	* surrounded with pool notifications.
440	>	* Records exception and possibly propagates.
441		*
442	<	* @return status upon exit
442	>	* @return status on exit
443		*/
444	<	private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) {
445	<	ForkJoinPool pool = w == null? null : w.pool;
446	<	int s;
447	<	while ((s = status) >= 0) {
269	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
270	<	if (pool == null || !pool.preJoin(this, maintainParallelism))
271	<	doAwaitDone();
272	<	if (((s = status) & INTERNAL_SIGNAL_MASK) != 0)
273	<	adjustPoolCountsOnUnblock(pool);
274	<	break;
275	<	}
276	<	}
444	>	private int setExceptionalCompletion(Throwable ex) {
445	>	int s = recordExceptionalCompletion(ex);
446	>	if ((s & DONE_MASK) == EXCEPTIONAL)
447	>	internalPropagateException(ex);
448		return s;
449		}
450
451		/**
452	<	* Timed version of awaitDone
282	<	* @return status upon exit
452	>	* Hook for exception propagation support for tasks with completers.
453		*/
454	<	private int awaitDone(ForkJoinWorkerThread w, long nanos) {
285	<	ForkJoinPool pool = w == null? null : w.pool;
286	<	int s;
287	<	while ((s = status) >= 0) {
288	<	if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) {
289	<	long startTime = System.nanoTime();
290	<	if (pool == null || !pool.preJoin(this, false))
291	<	doAwaitDone(startTime, nanos);
292	<	if ((s = status) >= 0) {
293	<	adjustPoolCountsOnCancelledWait(pool);
294	<	s = status;
295	<	}
296	<	if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0)
297	<	adjustPoolCountsOnUnblock(pool);
298	<	break;
299	<	}
300	<	}
301	<	return s;
454	>	void internalPropagateException(Throwable ex) {
455		}
456
457		/**
458	<	* Notifies pool that thread is unblocked. Called by signalled
459	<	* threads when woken by non-FJ threads (which is atypical).
458	>	* Cancels, ignoring any exceptions thrown by cancel. Used during
459	>	* worker and pool shutdown. Cancel is spec'ed not to throw any
460	>	* exceptions, but if it does anyway, we have no recourse during
461	>	* shutdown, so guard against this case.
462		*/
463	<	private void adjustPoolCountsOnUnblock(ForkJoinPool pool) {
464	<	int s;
465	<	do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK));
466	<	if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0)
467	<	pool.updateRunningCount(s);
463	>	static final void cancelIgnoringExceptions(ForkJoinTask<?> t) {
464	>	if (t != null && t.status >= 0) {
465	>	try {
466	>	t.cancel(false);
467	>	} catch (Throwable ignore) {
468	>	}
469	>	}
470		}
471
472		/**
473	<	* Notifies pool to adjust counts on cancelled or timed out wait.
473	>	* Removes exception node and clears status.
474		*/
475	<	private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) {
476	<	if (pool != null) {
477	<	int s;
478	<	while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) {
479	<	if (casStatus(s, s - 1)) {
480	<	pool.updateRunningCount(1);
475	>	private void clearExceptionalCompletion() {
476	>	int h = System.identityHashCode(this);
477	>	final ReentrantLock lock = exceptionTableLock;
478	>	lock.lock();
479	>	try {
480	>	ExceptionNode[] t = exceptionTable;
481	>	int i = h & (t.length - 1);
482	>	ExceptionNode e = t[i];
483	>	ExceptionNode pred = null;
484	>	while (e != null) {
485	>	ExceptionNode next = e.next;
486	>	if (e.get() == this) {
487	>	if (pred == null)
488	>	t[i] = next;
489	>	else
490	>	pred.next = next;
491		break;
492		}
493	+	pred = e;
494	+	e = next;
495		}
496	+	expungeStaleExceptions();
497	+	status = 0;
498	+	} finally {
499	+	lock.unlock();
500		}
501		}
502
503		/**
504	<	* Handles interruptions during waits.
505	<	*/
506	<	private void onInterruptedWait() {
507	<	ForkJoinWorkerThread w = getWorker();
508	<	if (w == null)
509	<	Thread.currentThread().interrupt(); // re-interrupt
510	<	else if (w.isTerminating())
511	<	cancelIgnoringExceptions();
512	<	// else if FJworker, ignore interrupt
513	<	}
341	<
342	<	// Recording and reporting exceptions
343	<
344	<	private void setDoneExceptionally(Throwable rex) {
345	<	exceptionMap.put(this, rex);
346	<	setCompletion(EXCEPTIONAL);
347	<	}
348	<
349	<	/**
350	<	* Throws the exception associated with status s.
504	>	* Returns a rethrowable exception for the given task, if
505	>	* available. To provide accurate stack traces, if the exception
506	>	* was not thrown by the current thread, we try to create a new
507	>	* exception of the same type as the one thrown, but with the
508	>	* recorded exception as its cause. If there is no such
509	>	* constructor, we instead try to use a no-arg constructor,
510	>	* followed by initCause, to the same effect. If none of these
511	>	* apply, or any fail due to other exceptions, we return the
512	>	* recorded exception, which is still correct, although it may
513	>	* contain a misleading stack trace.
514		*
515	<	* @throws the exception
353	<	*/
354	<	private void reportException(int s) {
355	<	if ((s &= COMPLETION_MASK) < NORMAL) {
356	<	if (s == CANCELLED)
357	<	throw new CancellationException();
358	<	else
359	<	rethrowException(exceptionMap.get(this));
360	<	}
361	<	}
362	<
363	<	/**
364	<	* Returns result or throws exception using j.u.c.Future conventions.
365	<	* Only call when isDone known to be true.
515	>	* @return the exception, or null if none
516		*/
517	<	private V reportFutureResult()
518	<	throws ExecutionException, InterruptedException {
519	<	int s = status & COMPLETION_MASK;
520	<	if (s < NORMAL) {
521	<	Throwable ex;
522	<	if (s == CANCELLED)
523	<	throw new CancellationException();
524	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
525	<	throw new ExecutionException(ex);
526	<	if (Thread.interrupted())
527	<	throw new InterruptedException();
517	>	private Throwable getThrowableException() {
518	>	if ((status & DONE_MASK) != EXCEPTIONAL)
519	>	return null;
520	>	int h = System.identityHashCode(this);
521	>	ExceptionNode e;
522	>	final ReentrantLock lock = exceptionTableLock;
523	>	lock.lock();
524	>	try {
525	>	expungeStaleExceptions();
526	>	ExceptionNode[] t = exceptionTable;
527	>	e = t[h & (t.length - 1)];
528	>	while (e != null && e.get() != this)
529	>	e = e.next;
530	>	} finally {
531	>	lock.unlock();
532		}
379	–	return getRawResult();
380	–	}
381	–
382	–	/**
383	–	* Returns result or throws exception using j.u.c.Future conventions
384	–	* with timeouts.
385	–	*/
386	–	private V reportTimedFutureResult()
387	–	throws InterruptedException, ExecutionException, TimeoutException {
533		Throwable ex;
534	<	int s = status & COMPLETION_MASK;
535	<	if (s == NORMAL)
536	<	return getRawResult();
537	<	if (s == CANCELLED)
538	<	throw new CancellationException();
539	<	if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null)
540	<	throw new ExecutionException(ex);
541	<	if (Thread.interrupted())
542	<	throw new InterruptedException();
543	<	throw new TimeoutException();
534	>	if (e == null || (ex = e.ex) == null)
535	>	return null;
536	>	if (false && e.thrower != Thread.currentThread().getId()) {
537	>	Class<? extends Throwable> ec = ex.getClass();
538	>	try {
539	>	Constructor<?> noArgCtor = null;
540	>	Constructor<?>[] cs = ec.getConstructors();// public ctors only
541	>	for (int i = 0; i < cs.length; ++i) {
542	>	Constructor<?> c = cs[i];
543	>	Class<?>[] ps = c.getParameterTypes();
544	>	if (ps.length == 0)
545	>	noArgCtor = c;
546	>	else if (ps.length == 1 && ps[0] == Throwable.class)
547	>	return (Throwable)(c.newInstance(ex));
548	>	}
549	>	if (noArgCtor != null) {
550	>	Throwable wx = (Throwable)(noArgCtor.newInstance());
551	>	wx.initCause(ex);
552	>	return wx;
553	>	}
554	>	} catch (Exception ignore) {
555	>	}
556	>	}
557	>	return ex;
558		}
559
401	–	// internal execution methods
402	–
560		/**
561	<	* Calls exec, recording completion, and rethrowing exception if
405	<	* encountered. Caller should normally check status before calling.
406	<	*
407	<	* @return true if completed normally
561	>	* Poll stale refs and remove them. Call only while holding lock.
562		*/
563	<	private boolean tryExec() {
564	<	try { // try block must contain only call to exec
565	<	if (!exec())
566	<	return false;
567	<	} catch (Throwable rex) {
568	<	setDoneExceptionally(rex);
569	<	rethrowException(rex);
570	<	return false; // not reached
563	>	private static void expungeStaleExceptions() {
564	>	for (Object x; (x = exceptionTableRefQueue.poll()) != null;) {
565	>	if (x instanceof ExceptionNode) {
566	>	int hashCode = ((ExceptionNode)x).hashCode;
567	>	ExceptionNode[] t = exceptionTable;
568	>	int i = hashCode & (t.length - 1);
569	>	ExceptionNode e = t[i];
570	>	ExceptionNode pred = null;
571	>	while (e != null) {
572	>	ExceptionNode next = e.next;
573	>	if (e == x) {
574	>	if (pred == null)
575	>	t[i] = next;
576	>	else
577	>	pred.next = next;
578	>	break;
579	>	}
580	>	pred = e;
581	>	e = next;
582	>	}
583	>	}
584		}
418	–	setNormalCompletion();
419	–	return true;
585		}
586
587		/**
588	<	* Main execution method used by worker threads. Invokes
589	<	* base computation unless already complete.
588	>	* If lock is available, poll stale refs and remove them.
589	>	* Called from ForkJoinPool when pools become quiescent.
590		*/
591	<	final void quietlyExec() {
592	<	if (status >= 0) {
591	>	static final void helpExpungeStaleExceptions() {
592	>	final ReentrantLock lock = exceptionTableLock;
593	>	if (lock.tryLock()) {
594		try {
595	<	if (!exec())
596	<	return;
597	<	} catch(Throwable rex) {
432	<	setDoneExceptionally(rex);
433	<	return;
595	>	expungeStaleExceptions();
596	>	} finally {
597	>	lock.unlock();
598		}
435	–	setNormalCompletion();
599		}
600		}
601
602		/**
603	<	* Calls exec(), recording but not rethrowing exception.
441	<	* Caller should normally check status before calling.
442	<	*
443	<	* @return true if completed normally
603	>	* A version of "sneaky throw" to relay exceptions
604		*/
605	<	private boolean tryQuietlyInvoke() {
606	<	try {
607	<	if (!exec())
608	<	return false;
609	<	} catch (Throwable rex) {
610	<	setDoneExceptionally(rex);
611	<	return false;
605	>	static void rethrow(final Throwable ex) {
606	>	if (ex != null) {
607	>	if (ex instanceof Error)
608	>	throw (Error)ex;
609	>	if (ex instanceof RuntimeException)
610	>	throw (RuntimeException)ex;
611	>	ForkJoinTask.<RuntimeException>uncheckedThrow(ex);
612		}
453	–	setNormalCompletion();
454	–	return true;
613		}
614
615		/**
616	<	* Cancels, ignoring any exceptions it throws.
616	>	* The sneaky part of sneaky throw, relying on generics
617	>	* limitations to evade compiler complaints about rethrowing
618	>	* unchecked exceptions
619		*/
620	<	final void cancelIgnoringExceptions() {
621	<	try {
622	<	cancel(false);
623	<	} catch(Throwable ignore) {
464	<	}
620	>	@SuppressWarnings("unchecked") static <T extends Throwable>
621	>	void uncheckedThrow(Throwable t) throws T {
622	>	if (t != null)
623	>	throw (T)t; // rely on vacuous cast
624		}
625
626		/**
627	<	* Main implementation of helpJoin
627	>	* Throws exception, if any, associated with the given status.
628		*/
629	<	private int busyJoin(ForkJoinWorkerThread w) {
630	<	int s;
631	<	ForkJoinTask<?> t;
632	<	while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null)
633	<	t.quietlyExec();
475	<	return (s >= 0)? awaitDone(w, false) : s; // block if no work
629	>	private void reportException(int s) {
630	>	if (s == CANCELLED)
631	>	throw new CancellationException();
632	>	if (s == EXCEPTIONAL)
633	>	rethrow(getThrowableException());
634		}
635
636		// public methods
637
638		/**
639	<	* Arranges to asynchronously execute this task.  While it is not
640	<	* necessarily enforced, it is a usage error to fork a task more
641	<	* than once unless it has completed and been reinitialized.  This
642	<	* method may be invoked only from within ForkJoinTask
643	<	* computations. Attempts to invoke in other contexts result in
644	<	* exceptions or errors possibly including ClassCastException.
645	<	*/
646	<	public final void fork() {
647	<	((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this);
639	>	* Arranges to asynchronously execute this task in the pool the
640	>	* current task is running in, if applicable, or using the {@link
641	>	* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}.  While
642	>	* it is not necessarily enforced, it is a usage error to fork a
643	>	* task more than once unless it has completed and been
644	>	* reinitialized.  Subsequent modifications to the state of this
645	>	* task or any data it operates on are not necessarily
646	>	* consistently observable by any thread other than the one
647	>	* executing it unless preceded by a call to {@link #join} or
648	>	* related methods, or a call to {@link #isDone} returning {@code
649	>	* true}.
650	>	*
651	>	* @return {@code this}, to simplify usage
652	>	*/
653	>	public final ForkJoinTask<V> fork() {
654	>	Thread t;
655	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)
656	>	((ForkJoinWorkerThread)t).workQueue.push(this);
657	>	else
658	>	ForkJoinPool.common.externalPush(this);
659	>	return this;
660		}
661
662		/**
663	<	* Returns the result of the computation when it is ready.
664	<	* This method differs from {@code get} in that abnormal
665	<	* completion results in RuntimeExceptions or Errors, not
666	<	* ExecutionExceptions.
663	>	* Returns the result of the computation when it {@link #isDone is
664	>	* done}.  This method differs from {@link #get()} in that
665	>	* abnormal completion results in {@code RuntimeException} or
666	>	* {@code Error}, not {@code ExecutionException}, and that
667	>	* interrupts of the calling thread do <em>not</em> cause the
668	>	* method to abruptly return by throwing {@code
669	>	* InterruptedException}.
670		*
671		* @return the computed result
672		*/
673		public final V join() {
674	<	ForkJoinWorkerThread w = getWorker();
675	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryExec())
676	<	reportException(awaitDone(w, true));
674	>	int s;
675	>	if ((s = doJoin() & DONE_MASK) != NORMAL)
676	>	reportException(s);
677		return getRawResult();
678		}
679
680		/**
681		* Commences performing this task, awaits its completion if
682	<	* necessary, and return its result.
682	>	* necessary, and returns its result, or throws an (unchecked)
683	>	* {@code RuntimeException} or {@code Error} if the underlying
684	>	* computation did so.
685		*
511	–	* @throws Throwable (a RuntimeException, Error, or unchecked
512	–	* exception) if the underlying computation did so
686		* @return the computed result
687		*/
688		public final V invoke() {
689	<	if (status >= 0 && tryExec())
690	<	return getRawResult();
691	<	else
692	<	return join();
689	>	int s;
690	>	if ((s = doInvoke() & DONE_MASK) != NORMAL)
691	>	reportException(s);
692	>	return getRawResult();
693		}
694
695		/**
696	<	* Forks both tasks, returning when {@code isDone} holds for
697	<	* both of them or an exception is encountered. This method may be
698	<	* invoked only from within ForkJoinTask computations. Attempts to
699	<	* invoke in other contexts result in exceptions or errors
700	<	* possibly including ClassCastException.
701	<	*
702	<	* @param t1 one task
703	<	* @param t2 the other task
704	<	* @throws NullPointerException if t1 or t2 are null
705	<	* @throws RuntimeException or Error if either task did so
696	>	* Forks the given tasks, returning when {@code isDone} holds for
697	>	* each task or an (unchecked) exception is encountered, in which
698	>	* case the exception is rethrown. If more than one task
699	>	* encounters an exception, then this method throws any one of
700	>	* these exceptions. If any task encounters an exception, the
701	>	* other may be cancelled. However, the execution status of
702	>	* individual tasks is not guaranteed upon exceptional return. The
703	>	* status of each task may be obtained using {@link
704	>	* #getException()} and related methods to check if they have been
705	>	* cancelled, completed normally or exceptionally, or left
706	>	* unprocessed.
707	>	*
708	>	* @param t1 the first task
709	>	* @param t2 the second task
710	>	* @throws NullPointerException if any task is null
711		*/
712	<	public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) {
712	>	public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) {
713	>	int s1, s2;
714		t2.fork();
715	<	t1.invoke();
716	<	t2.join();
715	>	if ((s1 = t1.doInvoke() & DONE_MASK) != NORMAL)
716	>	t1.reportException(s1);
717	>	if ((s2 = t2.doJoin() & DONE_MASK) != NORMAL)
718	>	t2.reportException(s2);
719		}
720
721		/**
722	<	* Forks the given tasks, returning when {@code isDone} holds
723	<	* for all of them. If any task encounters an exception, others
724	<	* may be cancelled.  This method may be invoked only from within
725	<	* ForkJoinTask computations. Attempts to invoke in other contexts
726	<	* result in exceptions or errors possibly including ClassCastException.
722	>	* Forks the given tasks, returning when {@code isDone} holds for
723	>	* each task or an (unchecked) exception is encountered, in which
724	>	* case the exception is rethrown. If more than one task
725	>	* encounters an exception, then this method throws any one of
726	>	* these exceptions. If any task encounters an exception, others
727	>	* may be cancelled. However, the execution status of individual
728	>	* tasks is not guaranteed upon exceptional return. The status of
729	>	* each task may be obtained using {@link #getException()} and
730	>	* related methods to check if they have been cancelled, completed
731	>	* normally or exceptionally, or left unprocessed.
732		*
733	<	* @param tasks the array of tasks
734	<	* @throws NullPointerException if tasks or any element are null
549	<	* @throws RuntimeException or Error if any task did so
733	>	* @param tasks the tasks
734	>	* @throws NullPointerException if any task is null
735		*/
736		public static void invokeAll(ForkJoinTask<?>... tasks) {
737		Throwable ex = null;
#	Line 559 | Line 744 | public abstract class ForkJoinTask<V> im
744		}
745		else if (i != 0)
746		t.fork();
747	<	else {
748	<	t.quietlyInvoke();
564	<	if (ex == null)
565	<	ex = t.getException();
566	<	}
747	>	else if (t.doInvoke() < NORMAL && ex == null)
748	>	ex = t.getException();
749		}
750		for (int i = 1; i <= last; ++i) {
751		ForkJoinTask<?> t = tasks[i];
752		if (t != null) {
753		if (ex != null)
754		t.cancel(false);
755	<	else {
756	<	t.quietlyJoin();
575	<	if (ex == null)
576	<	ex = t.getException();
577	<	}
755	>	else if (t.doJoin() < NORMAL)
756	>	ex = t.getException();
757		}
758		}
759		if (ex != null)
760	<	rethrowException(ex);
760	>	rethrow(ex);
761		}
762
763		/**
764	<	* Forks all tasks in the collection, returning when
765	<	* {@code isDone} holds for all of them. If any task
766	<	* encounters an exception, others may be cancelled.  This method
767	<	* may be invoked only from within ForkJoinTask
768	<	* computations. Attempts to invoke in other contexts result in
769	<	* exceptions or errors possibly including ClassCastException.
764	>	* Forks all tasks in the specified collection, returning when
765	>	* {@code isDone} holds for each task or an (unchecked) exception
766	>	* is encountered, in which case the exception is rethrown. If
767	>	* more than one task encounters an exception, then this method
768	>	* throws any one of these exceptions. If any task encounters an
769	>	* exception, others may be cancelled. However, the execution
770	>	* status of individual tasks is not guaranteed upon exceptional
771	>	* return. The status of each task may be obtained using {@link
772	>	* #getException()} and related methods to check if they have been
773	>	* cancelled, completed normally or exceptionally, or left
774	>	* unprocessed.
775		*
776		* @param tasks the collection of tasks
777	+	* @return the tasks argument, to simplify usage
778		* @throws NullPointerException if tasks or any element are null
594	–	* @throws RuntimeException or Error if any task did so
779		*/
780	<	public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) {
781	<	if (!(tasks instanceof List)) {
782	<	invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()]));
783	<	return;
780	>	public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) {
781	>	if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) {
782	>	invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()]));
783	>	return tasks;
784		}
785	+	@SuppressWarnings("unchecked")
786		List<? extends ForkJoinTask<?>> ts =
787	<	(List<? extends ForkJoinTask<?>>)tasks;
787	>	(List<? extends ForkJoinTask<?>>) tasks;
788		Throwable ex = null;
789		int last = ts.size() - 1;
790		for (int i = last; i >= 0; --i) {
#	Line 610 | Line 795 | public abstract class ForkJoinTask<V> im
795		}
796		else if (i != 0)
797		t.fork();
798	<	else {
799	<	t.quietlyInvoke();
615	<	if (ex == null)
616	<	ex = t.getException();
617	<	}
798	>	else if (t.doInvoke() < NORMAL && ex == null)
799	>	ex = t.getException();
800		}
801		for (int i = 1; i <= last; ++i) {
802		ForkJoinTask<?> t = ts.get(i);
803		if (t != null) {
804		if (ex != null)
805		t.cancel(false);
806	<	else {
807	<	t.quietlyJoin();
626	<	if (ex == null)
627	<	ex = t.getException();
628	<	}
806	>	else if (t.doJoin() < NORMAL)
807	>	ex = t.getException();
808		}
809		}
810		if (ex != null)
811	<	rethrowException(ex);
811	>	rethrow(ex);
812	>	return tasks;
813		}
814
815		/**
816	<	* Returns true if the computation performed by this task has
817	<	* completed (or has been cancelled).
816	>	* Attempts to cancel execution of this task. This attempt will
817	>	* fail if the task has already completed or could not be
818	>	* cancelled for some other reason. If successful, and this task
819	>	* has not started when {@code cancel} is called, execution of
820	>	* this task is suppressed. After this method returns
821	>	* successfully, unless there is an intervening call to {@link
822	>	* #reinitialize}, subsequent calls to {@link #isCancelled},
823	>	* {@link #isDone}, and {@code cancel} will return {@code true}
824	>	* and calls to {@link #join} and related methods will result in
825	>	* {@code CancellationException}.
826		*
827	<	* @return true if this computation has completed
827	>	* <p>This method may be overridden in subclasses, but if so, must
828	>	* still ensure that these properties hold. In particular, the
829	>	* {@code cancel} method itself must not throw exceptions.
830	>	*
831	>	* <p>This method is designed to be invoked by <em>other</em>
832	>	* tasks. To terminate the current task, you can just return or
833	>	* throw an unchecked exception from its computation method, or
834	>	* invoke {@link #completeExceptionally}.
835	>	*
836	>	* @param mayInterruptIfRunning this value has no effect in the
837	>	* default implementation because interrupts are not used to
838	>	* control cancellation.
839	>	*
840	>	* @return {@code true} if this task is now cancelled
841		*/
842	+	public boolean cancel(boolean mayInterruptIfRunning) {
843	+	return (setCompletion(CANCELLED) & DONE_MASK) == CANCELLED;
844	+	}
845	+
846		public final boolean isDone() {
847		return status < 0;
848		}
849
645	–	/**
646	–	* Returns true if this task was cancelled.
647	–	*
648	–	* @return true if this task was cancelled
649	–	*/
850		public final boolean isCancelled() {
851	<	return (status & COMPLETION_MASK) == CANCELLED;
851	>	return (status & DONE_MASK) == CANCELLED;
852		}
853
854		/**
855	<	* Asserts that the results of this task's computation will not be
656	<	* used. If a cancellation occurs before attempting to execute this
657	<	* task, then execution will be suppressed, {@code isCancelled}
658	<	* will report true, and {@code join} will result in a
659	<	* {@code CancellationException} being thrown. Otherwise, when
660	<	* cancellation races with completion, there are no guarantees
661	<	* about whether {@code isCancelled} will report true, whether
662	<	* {@code join} will return normally or via an exception, or
663	<	* whether these behaviors will remain consistent upon repeated
664	<	* invocation.
855	>	* Returns {@code true} if this task threw an exception or was cancelled.
856		*
857	<	* <p>This method may be overridden in subclasses, but if so, must
667	<	* still ensure that these minimal properties hold. In particular,
668	<	* the cancel method itself must not throw exceptions.
669	<	*
670	<	* <p> This method is designed to be invoked by <em>other</em>
671	<	* tasks. To terminate the current task, you can just return or
672	<	* throw an unchecked exception from its computation method, or
673	<	* invoke {@code completeExceptionally}.
674	<	*
675	<	* @param mayInterruptIfRunning this value is ignored in the
676	<	* default implementation because tasks are not in general
677	<	* cancelled via interruption.
678	<	*
679	<	* @return true if this task is now cancelled
857	>	* @return {@code true} if this task threw an exception or was cancelled
858		*/
859	<	public boolean cancel(boolean mayInterruptIfRunning) {
860	<	setCompletion(CANCELLED);
683	<	return (status & COMPLETION_MASK) == CANCELLED;
859	>	public final boolean isCompletedAbnormally() {
860	>	return status < NORMAL;
861		}
862
863		/**
864	<	* Returns true if this task threw an exception or was cancelled.
864	>	* Returns {@code true} if this task completed without throwing an
865	>	* exception and was not cancelled.
866		*
867	<	* @return true if this task threw an exception or was cancelled
867	>	* @return {@code true} if this task completed without throwing an
868	>	* exception and was not cancelled
869		*/
870	<	public final boolean isCompletedAbnormally() {
871	<	return (status & COMPLETION_MASK) < NORMAL;
870	>	public final boolean isCompletedNormally() {
871	>	return (status & DONE_MASK) == NORMAL;
872		}
873
874		/**
875		* Returns the exception thrown by the base computation, or a
876	<	* CancellationException if cancelled, or null if none or if the
877	<	* method has not yet completed.
876	>	* {@code CancellationException} if cancelled, or {@code null} if
877	>	* none or if the method has not yet completed.
878		*
879	<	* @return the exception, or null if none
879	>	* @return the exception, or {@code null} if none
880		*/
881		public final Throwable getException() {
882	<	int s = status & COMPLETION_MASK;
883	<	if (s >= NORMAL)
884	<	return null;
885	<	if (s == CANCELLED)
707	<	return new CancellationException();
708	<	return exceptionMap.get(this);
882	>	int s = status & DONE_MASK;
883	>	return ((s >= NORMAL)    ? null :
884	>	(s == CANCELLED) ? new CancellationException() :
885	>	getThrowableException());
886		}
887
888		/**
#	Line 714 | Line 891 | public abstract class ForkJoinTask<V> im
891		* {@code join} and related operations. This method may be used
892		* to induce exceptions in asynchronous tasks, or to force
893		* completion of tasks that would not otherwise complete.  Its use
894	<	* in other situations is likely to be wrong.  This method is
894	>	* in other situations is discouraged.  This method is
895		* overridable, but overridden versions must invoke {@code super}
896		* implementation to maintain guarantees.
897		*
898	<	* @param ex the exception to throw. If this exception is
899	<	* not a RuntimeException or Error, the actual exception thrown
900	<	* will be a RuntimeException with cause ex.
898	>	* @param ex the exception to throw. If this exception is not a
899	>	* {@code RuntimeException} or {@code Error}, the actual exception
900	>	* thrown will be a {@code RuntimeException} with cause {@code ex}.
901		*/
902		public void completeExceptionally(Throwable ex) {
903	<	setDoneExceptionally((ex instanceof RuntimeException) ||
904	<	(ex instanceof Error)? ex :
905	<	new RuntimeException(ex));
903	>	setExceptionalCompletion((ex instanceof RuntimeException) ||
904	>	(ex instanceof Error) ? ex :
905	>	new RuntimeException(ex));
906		}
907
908		/**
909		* Completes this task, and if not already aborted or cancelled,
910	<	* returning a {@code null} result upon {@code join} and related
911	<	* operations. This method may be used to provide results for
912	<	* asynchronous tasks, or to provide alternative handling for
913	<	* tasks that would not otherwise complete normally. Its use in
914	<	* other situations is likely to be wrong. This method is
915	<	* overridable, but overridden versions must invoke {@code super}
916	<	* implementation to maintain guarantees.
910	>	* returning the given value as the result of subsequent
911	>	* invocations of {@code join} and related operations. This method
912	>	* may be used to provide results for asynchronous tasks, or to
913	>	* provide alternative handling for tasks that would not otherwise
914	>	* complete normally. Its use in other situations is
915	>	* discouraged. This method is overridable, but overridden
916	>	* versions must invoke {@code super} implementation to maintain
917	>	* guarantees.
918		*
919		* @param value the result value for this task
920		*/
921		public void complete(V value) {
922		try {
923		setRawResult(value);
924	<	} catch(Throwable rex) {
925	<	setDoneExceptionally(rex);
924	>	} catch (Throwable rex) {
925	>	setExceptionalCompletion(rex);
926		return;
927		}
928	<	setNormalCompletion();
928	>	setCompletion(NORMAL);
929		}
930
931	<	public final V get() throws InterruptedException, ExecutionException {
932	<	ForkJoinWorkerThread w = getWorker();
933	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
934	<	awaitDone(w, true);
935	<	return reportFutureResult();
936	<	}
937	<
938	<	public final V get(long timeout, TimeUnit unit)
939	<	throws InterruptedException, ExecutionException, TimeoutException {
940	<	ForkJoinWorkerThread w = getWorker();
763	<	if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke())
764	<	awaitDone(w, unit.toNanos(timeout));
765	<	return reportTimedFutureResult();
931	>	/**
932	>	* Completes this task normally without setting a value. The most
933	>	* recent value established by {@link #setRawResult} (or {@code
934	>	* null} by default) will be returned as the result of subsequent
935	>	* invocations of {@code join} and related operations.
936	>	*
937	>	* @since 1.8
938	>	*/
939	>	public final void quietlyComplete() {
940	>	setCompletion(NORMAL);
941		}
942
943		/**
944	<	* Possibly executes other tasks until this task is ready, then
945	<	* returns the result of the computation.  This method may be more
771	<	* efficient than {@code join}, but is only applicable when
772	<	* there are no potential dependencies between continuation of the
773	<	* current task and that of any other task that might be executed
774	<	* while helping. (This usually holds for pure divide-and-conquer
775	<	* tasks). This method may be invoked only from within
776	<	* ForkJoinTask computations. Attempts to invoke in other contexts
777	<	* result in exceptions or errors possibly including ClassCastException.
944	>	* Waits if necessary for the computation to complete, and then
945	>	* retrieves its result.
946		*
947		* @return the computed result
948	+	* @throws CancellationException if the computation was cancelled
949	+	* @throws ExecutionException if the computation threw an
950	+	* exception
951	+	* @throws InterruptedException if the current thread is not a
952	+	* member of a ForkJoinPool and was interrupted while waiting
953		*/
954	<	public final V helpJoin() {
955	<	ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread());
956	<	if (status < 0 || !w.unpushTask(this) || !tryExec())
957	<	reportException(busyJoin(w));
954	>	public final V get() throws InterruptedException, ExecutionException {
955	>	int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ?
956	>	doJoin() : externalInterruptibleAwaitDone();
957	>	Throwable ex;
958	>	if ((s &= DONE_MASK) == CANCELLED)
959	>	throw new CancellationException();
960	>	if (s == EXCEPTIONAL && (ex = getThrowableException()) != null)
961	>	throw new ExecutionException(ex);
962		return getRawResult();
963		}
964
965		/**
966	<	* Possibly executes other tasks until this task is ready.  This
967	<	* method may be invoked only from within ForkJoinTask
968	<	* computations. Attempts to invoke in other contexts result in
969	<	* exceptions or errors possibly including ClassCastException.
966	>	* Waits if necessary for at most the given time for the computation
967	>	* to complete, and then retrieves its result, if available.
968	>	*
969	>	* @param timeout the maximum time to wait
970	>	* @param unit the time unit of the timeout argument
971	>	* @return the computed result
972	>	* @throws CancellationException if the computation was cancelled
973	>	* @throws ExecutionException if the computation threw an
974	>	* exception
975	>	* @throws InterruptedException if the current thread is not a
976	>	* member of a ForkJoinPool and was interrupted while waiting
977	>	* @throws TimeoutException if the wait timed out
978		*/
979	<	public final void quietlyHelpJoin() {
980	<	if (status >= 0) {
981	<	ForkJoinWorkerThread w =
982	<	(ForkJoinWorkerThread)(Thread.currentThread());
983	<	if (!w.unpushTask(this) || !tryQuietlyInvoke())
984	<	busyJoin(w);
979	>	public final V get(long timeout, TimeUnit unit)
980	>	throws InterruptedException, ExecutionException, TimeoutException {
981	>	if (Thread.interrupted())
982	>	throw new InterruptedException();
983	>	// Messy in part because we measure in nanosecs, but wait in millisecs
984	>	int s; long ms;
985	>	long ns = unit.toNanos(timeout);
986	>	if ((s = status) >= 0 && ns > 0L) {
987	>	long deadline = System.nanoTime() + ns;
988	>	ForkJoinPool p = null;
989	>	ForkJoinPool.WorkQueue w = null;
990	>	Thread t = Thread.currentThread();
991	>	if (t instanceof ForkJoinWorkerThread) {
992	>	ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t;
993	>	p = wt.pool;
994	>	w = wt.workQueue;
995	>	p.helpJoinOnce(w, this); // no retries on failure
996	>	}
997	>	else
998	>	ForkJoinPool.externalHelpJoin(this);
999	>	boolean canBlock = false;
1000	>	boolean interrupted = false;
1001	>	try {
1002	>	while ((s = status) >= 0) {
1003	>	if (w != null && w.qlock < 0)
1004	>	cancelIgnoringExceptions(this);
1005	>	else if (!canBlock) {
1006	>	if (p == null || p.tryCompensate())
1007	>	canBlock = true;
1008	>	}
1009	>	else {
1010	>	if ((ms = TimeUnit.NANOSECONDS.toMillis(ns)) > 0L &&
1011	>	U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
1012	>	synchronized (this) {
1013	>	if (status >= 0) {
1014	>	try {
1015	>	wait(ms);
1016	>	} catch (InterruptedException ie) {
1017	>	if (p == null)
1018	>	interrupted = true;
1019	>	}
1020	>	}
1021	>	else
1022	>	notifyAll();
1023	>	}
1024	>	}
1025	>	if ((s = status) < 0 || interrupted ||
1026	>	(ns = deadline - System.nanoTime()) <= 0L)
1027	>	break;
1028	>	}
1029	>	}
1030	>	} finally {
1031	>	if (p != null && canBlock)
1032	>	p.incrementActiveCount();
1033	>	}
1034	>	if (interrupted)
1035	>	throw new InterruptedException();
1036		}
1037	+	if ((s &= DONE_MASK) != NORMAL) {
1038	+	Throwable ex;
1039	+	if (s == CANCELLED)
1040	+	throw new CancellationException();
1041	+	if (s != EXCEPTIONAL)
1042	+	throw new TimeoutException();
1043	+	if ((ex = getThrowableException()) != null)
1044	+	throw new ExecutionException(ex);
1045	+	}
1046	+	return getRawResult();
1047		}
1048
1049		/**
1050	<	* Joins this task, without returning its result or throwing an
1050	>	* Joins this task, without returning its result or throwing its
1051		* exception. This method may be useful when processing
1052		* collections of tasks when some have been cancelled or otherwise
1053		* known to have aborted.
1054		*/
1055		public final void quietlyJoin() {
1056	<	if (status >= 0) {
811	<	ForkJoinWorkerThread w = getWorker();
812	<	if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke())
813	<	awaitDone(w, true);
814	<	}
1056	>	doJoin();
1057		}
1058
1059		/**
1060		* Commences performing this task and awaits its completion if
1061	<	* necessary, without returning its result or throwing an
1062	<	* exception. This method may be useful when processing
821	<	* collections of tasks when some have been cancelled or otherwise
822	<	* known to have aborted.
1061	>	* necessary, without returning its result or throwing its
1062	>	* exception.
1063		*/
1064		public final void quietlyInvoke() {
1065	<	if (status >= 0 && !tryQuietlyInvoke())
826	<	quietlyJoin();
1065	>	doInvoke();
1066		}
1067
1068		/**
1069		* Possibly executes tasks until the pool hosting the current task
1070	<	* {@link ForkJoinPool#isQuiescent}. This method may be of use in
1071	<	* designs in which many tasks are forked, but none are explicitly
1072	<	* joined, instead executing them until all are processed.
1070	>	* {@linkplain ForkJoinPool#isQuiescent is quiescent}.  This
1071	>	* method may be of use in designs in which many tasks are forked,
1072	>	* but none are explicitly joined, instead executing them until
1073	>	* all are processed.
1074		*/
1075		public static void helpQuiesce() {
1076	<	((ForkJoinWorkerThread)(Thread.currentThread())).
1077	<	helpQuiescePool();
1076	>	Thread t;
1077	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) {
1078	>	ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t;
1079	>	wt.pool.helpQuiescePool(wt.workQueue);
1080	>	}
1081	>	else
1082	>	ForkJoinPool.quiesceCommonPool();
1083		}
1084
1085		/**
#	Line 843 | Line 1088 | public abstract class ForkJoinTask<V> im
1088		* this task, but only if reuse occurs when this task has either
1089		* never been forked, or has been forked, then completed and all
1090		* outstanding joins of this task have also completed. Effects
1091	<	* under any other usage conditions are not guaranteed, and are
1092	<	* almost surely wrong. This method may be useful when executing
1091	>	* under any other usage conditions are not guaranteed.
1092	>	* This method may be useful when executing
1093		* pre-constructed trees of subtasks in loops.
1094	+	*
1095	+	* <p>Upon completion of this method, {@code isDone()} reports
1096	+	* {@code false}, and {@code getException()} reports {@code
1097	+	* null}. However, the value returned by {@code getRawResult} is
1098	+	* unaffected. To clear this value, you can invoke {@code
1099	+	* setRawResult(null)}.
1100		*/
1101		public void reinitialize() {
1102	<	if ((status & COMPLETION_MASK) == EXCEPTIONAL)
1103	<	exceptionMap.remove(this);
1104	<	status = 0;
1102	>	if ((status & DONE_MASK) == EXCEPTIONAL)
1103	>	clearExceptionalCompletion();
1104	>	else
1105	>	status = 0;
1106		}
1107
1108		/**
1109		* Returns the pool hosting the current task execution, or null
1110	<	* if this task is executing outside of any pool.
1110	>	* if this task is executing outside of any ForkJoinPool.
1111		*
1112	<	* @return the pool, or null if none
1112	>	* @see #inForkJoinPool
1113	>	* @return the pool, or {@code null} if none
1114		*/
1115		public static ForkJoinPool getPool() {
1116		Thread t = Thread.currentThread();
1117	<	return ((t instanceof ForkJoinWorkerThread)?
1118	<	((ForkJoinWorkerThread)t).pool : null);
1117	>	return (t instanceof ForkJoinWorkerThread) ?
1118	>	((ForkJoinWorkerThread) t).pool : null;
1119	>	}
1120	>
1121	>	/**
1122	>	* Returns {@code true} if the current thread is a {@link
1123	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation.
1124	>	*
1125	>	* @return {@code true} if the current thread is a {@link
1126	>	* ForkJoinWorkerThread} executing as a ForkJoinPool computation,
1127	>	* or {@code false} otherwise
1128	>	*/
1129	>	public static boolean inForkJoinPool() {
1130	>	return Thread.currentThread() instanceof ForkJoinWorkerThread;
1131		}
1132
1133		/**
1134		* Tries to unschedule this task for execution. This method will
1135	<	* typically succeed if this task is the most recently forked task
1136	<	* by the current thread, and has not commenced executing in
1137	<	* another thread.  This method may be useful when arranging
1138	<	* alternative local processing of tasks that could have been, but
1139	<	* were not, stolen. This method may be invoked only from within
875	<	* ForkJoinTask computations. Attempts to invoke in other contexts
876	<	* result in exceptions or errors possibly including ClassCastException.
1135	>	* typically (but is not guaranteed to) succeed if this task is
1136	>	* the most recently forked task by the current thread, and has
1137	>	* not commenced executing in another thread.  This method may be
1138	>	* useful when arranging alternative local processing of tasks
1139	>	* that could have been, but were not, stolen.
1140		*
1141	<	* @return true if unforked
1141	>	* @return {@code true} if unforked
1142		*/
1143		public boolean tryUnfork() {
1144	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this);
1144	>	Thread t;
1145	>	return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
1146	>	((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) :
1147	>	ForkJoinPool.tryExternalUnpush(this));
1148		}
1149
1150		/**
#	Line 890 | Line 1156 | public abstract class ForkJoinTask<V> im
1156		* @return the number of tasks
1157		*/
1158		public static int getQueuedTaskCount() {
1159	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).
1160	<	getQueueSize();
1159	>	Thread t; ForkJoinPool.WorkQueue q;
1160	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)
1161	>	q = ((ForkJoinWorkerThread)t).workQueue;
1162	>	else
1163	>	q = ForkJoinPool.commonSubmitterQueue();
1164	>	return (q == null) ? 0 : q.queueSize();
1165		}
1166
1167		/**
1168		* Returns an estimate of how many more locally queued tasks are
1169		* held by the current worker thread than there are other worker
1170	<	* threads that might steal them.  This value may be useful for
1170	>	* threads that might steal them, or zero if this thread is not
1171	>	* operating in a ForkJoinPool. This value may be useful for
1172		* heuristic decisions about whether to fork other tasks. In many
1173		* usages of ForkJoinTasks, at steady state, each worker should
1174		* aim to maintain a small constant surplus (for example, 3) of
#	Line 907 | Line 1178 | public abstract class ForkJoinTask<V> im
1178		* @return the surplus number of tasks, which may be negative
1179		*/
1180		public static int getSurplusQueuedTaskCount() {
1181	<	return ((ForkJoinWorkerThread)(Thread.currentThread()))
911	<	.getEstimatedSurplusTaskCount();
1181	>	return ForkJoinPool.getSurplusQueuedTaskCount();
1182		}
1183
1184		// Extension methods
1185
1186		/**
1187	<	* Returns the result that would be returned by {@code join},
1188	<	* even if this task completed abnormally, or null if this task is
1189	<	* not known to have been completed.  This method is designed to
1190	<	* aid debugging, as well as to support extensions. Its use in any
1191	<	* other context is discouraged.
1187	>	* Returns the result that would be returned by {@link #join}, even
1188	>	* if this task completed abnormally, or {@code null} if this task
1189	>	* is not known to have been completed.  This method is designed
1190	>	* to aid debugging, as well as to support extensions. Its use in
1191	>	* any other context is discouraged.
1192		*
1193	<	* @return the result, or null if not completed
1193	>	* @return the result, or {@code null} if not completed
1194		*/
1195		public abstract V getRawResult();
1196
#	Line 934 | Line 1204 | public abstract class ForkJoinTask<V> im
1204		protected abstract void setRawResult(V value);
1205
1206		/**
1207	<	* Immediately performs the base action of this task.  This method
1208	<	* is designed to support extensions, and should not in general be
1209	<	* called otherwise. The return value controls whether this task
1210	<	* is considered to be done normally. It may return false in
1207	>	* Immediately performs the base action of this task and returns
1208	>	* true if, upon return from this method, this task is guaranteed
1209	>	* to have completed normally. This method may return false
1210	>	* otherwise, to indicate that this task is not necessarily
1211	>	* complete (or is not known to be complete), for example in
1212		* asynchronous actions that require explicit invocations of
1213	<	* {@code complete} to become joinable. It may throw exceptions
1214	<	* to indicate abnormal exit.
1213	>	* completion methods. This method may also throw an (unchecked)
1214	>	* exception to indicate abnormal exit. This method is designed to
1215	>	* support extensions, and should not in general be called
1216	>	* otherwise.
1217		*
1218	<	* @return true if completed normally
946	<	* @throws Error or RuntimeException if encountered during computation
1218	>	* @return {@code true} if this task is known to have completed normally
1219		*/
1220		protected abstract boolean exec();
1221
1222		/**
1223	<	* Returns, but does not unschedule or execute, the task queued by
1224	<	* the current thread but not yet executed, if one is
1223	>	* Returns, but does not unschedule or execute, a task queued by
1224	>	* the current thread but not yet executed, if one is immediately
1225		* available. There is no guarantee that this task will actually
1226	<	* be polled or executed next.  This method is designed primarily
1227	<	* to support extensions, and is unlikely to be useful otherwise.
1228	<	* This method may be invoked only from within ForkJoinTask
1229	<	* computations. Attempts to invoke in other contexts result in
1230	<	* exceptions or errors possibly including ClassCastException.
1226	>	* be polled or executed next. Conversely, this method may return
1227	>	* null even if a task exists but cannot be accessed without
1228	>	* contention with other threads.  This method is designed
1229	>	* primarily to support extensions, and is unlikely to be useful
1230	>	* otherwise.
1231		*
1232	<	* @return the next task, or null if none are available
1232	>	* @return the next task, or {@code null} if none are available
1233		*/
1234		protected static ForkJoinTask<?> peekNextLocalTask() {
1235	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask();
1235	>	Thread t; ForkJoinPool.WorkQueue q;
1236	>	if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)
1237	>	q = ((ForkJoinWorkerThread)t).workQueue;
1238	>	else
1239	>	q = ForkJoinPool.commonSubmitterQueue();
1240	>	return (q == null) ? null : q.peek();
1241		}
1242
1243		/**
1244		* Unschedules and returns, without executing, the next task
1245	<	* queued by the current thread but not yet executed.  This method
1246	<	* is designed primarily to support extensions, and is unlikely to
1247	<	* be useful otherwise.  This method may be invoked only from
1248	<	* within ForkJoinTask computations. Attempts to invoke in other
972	<	* contexts result in exceptions or errors possibly including
973	<	* ClassCastException.
1245	>	* queued by the current thread but not yet executed, if the
1246	>	* current thread is operating in a ForkJoinPool.  This method is
1247	>	* designed primarily to support extensions, and is unlikely to be
1248	>	* useful otherwise.
1249		*
1250	<	* @return the next task, or null if none are available
1250	>	* @return the next task, or {@code null} if none are available
1251		*/
1252		protected static ForkJoinTask<?> pollNextLocalTask() {
1253	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask();
1253	>	Thread t;
1254	>	return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
1255	>	((ForkJoinWorkerThread)t).workQueue.nextLocalTask() :
1256	>	null;
1257		}
1258
1259		/**
1260	<	* Unschedules and returns, without executing, the next task
1260	>	* If the current thread is operating in a ForkJoinPool,
1261	>	* unschedules and returns, without executing, the next task
1262		* queued by the current thread but not yet executed, if one is
1263		* available, or if not available, a task that was forked by some
1264		* other thread, if available. Availability may be transient, so a
1265	<	* {@code null} result does not necessarily imply quiescence
1266	<	* of the pool this task is operating in.  This method is designed
1265	>	* {@code null} result does not necessarily imply quiescence of
1266	>	* the pool this task is operating in.  This method is designed
1267		* primarily to support extensions, and is unlikely to be useful
1268	<	* otherwise.  This method may be invoked only from within
990	<	* ForkJoinTask computations. Attempts to invoke in other contexts
991	<	* result in exceptions or errors possibly including
992	<	* ClassCastException.
1268	>	* otherwise.
1269		*
1270	<	* @return a task, or null if none are available
1270	>	* @return a task, or {@code null} if none are available
1271		*/
1272		protected static ForkJoinTask<?> pollTask() {
1273	<	return ((ForkJoinWorkerThread)(Thread.currentThread())).
1274	<	pollTask();
1273	>	Thread t; ForkJoinWorkerThread wt;
1274	>	return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
1275	>	(wt = (ForkJoinWorkerThread)t).pool.nextTaskFor(wt.workQueue) :
1276	>	null;
1277	>	}
1278	>
1279	>	// tag operations
1280	>
1281	>	/**
1282	>	* Returns the tag for this task.
1283	>	*
1284	>	* @return the tag for this task
1285	>	* @since 1.8
1286	>	*/
1287	>	public final short getForkJoinTaskTag() {
1288	>	return (short)status;
1289	>	}
1290	>
1291	>	/**
1292	>	* Atomically sets the tag value for this task.
1293	>	*
1294	>	* @param tag the tag value
1295	>	* @return the previous value of the tag
1296	>	* @since 1.8
1297	>	*/
1298	>	public final short setForkJoinTaskTag(short tag) {
1299	>	for (int s;;) {
1300	>	if (U.compareAndSwapInt(this, STATUS, s = status,
1301	>	(s & ~SMASK) | (tag & SMASK)))
1302	>	return (short)s;
1303	>	}
1304	>	}
1305	>
1306	>	/**
1307	>	* Atomically conditionally sets the tag value for this task.
1308	>	* Among other applications, tags can be used as visit markers
1309	>	* in tasks operating on graphs, as in methods that check: {@code
1310	>	* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))}
1311	>	* before processing, otherwise exiting because the node has
1312	>	* already been visited.
1313	>	*
1314	>	* @param e the expected tag value
1315	>	* @param tag the new tag value
1316	>	* @return true if successful; i.e., the current value was
1317	>	* equal to e and is now tag.
1318	>	* @since 1.8
1319	>	*/
1320	>	public final boolean compareAndSetForkJoinTaskTag(short e, short tag) {
1321	>	for (int s;;) {
1322	>	if ((short)(s = status) != e)
1323	>	return false;
1324	>	if (U.compareAndSwapInt(this, STATUS, s,
1325	>	(s & ~SMASK) | (tag & SMASK)))
1326	>	return true;
1327	>	}
1328	>	}
1329	>
1330	>	/**
1331	>	* Adapter for Runnables. This implements RunnableFuture
1332	>	* to be compliant with AbstractExecutorService constraints
1333	>	* when used in ForkJoinPool.
1334	>	*/
1335	>	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
1336	>	implements RunnableFuture<T> {
1337	>	final Runnable runnable;
1338	>	T result;
1339	>	AdaptedRunnable(Runnable runnable, T result) {
1340	>	if (runnable == null) throw new NullPointerException();
1341	>	this.runnable = runnable;
1342	>	this.result = result; // OK to set this even before completion
1343	>	}
1344	>	public final T getRawResult() { return result; }
1345	>	public final void setRawResult(T v) { result = v; }
1346	>	public final boolean exec() { runnable.run(); return true; }
1347	>	public final void run() { invoke(); }
1348	>	private static final long serialVersionUID = 5232453952276885070L;
1349	>	}
1350	>
1351	>	/**
1352	>	* Adapter for Runnables without results
1353	>	*/
1354	>	static final class AdaptedRunnableAction extends ForkJoinTask<Void>
1355	>	implements RunnableFuture<Void> {
1356	>	final Runnable runnable;
1357	>	AdaptedRunnableAction(Runnable runnable) {
1358	>	if (runnable == null) throw new NullPointerException();
1359	>	this.runnable = runnable;
1360	>	}
1361	>	public final Void getRawResult() { return null; }
1362	>	public final void setRawResult(Void v) { }
1363	>	public final boolean exec() { runnable.run(); return true; }
1364	>	public final void run() { invoke(); }
1365	>	private static final long serialVersionUID = 5232453952276885070L;
1366	>	}
1367	>
1368	>	/**
1369	>	* Adapter for Callables
1370	>	*/
1371	>	static final class AdaptedCallable<T> extends ForkJoinTask<T>
1372	>	implements RunnableFuture<T> {
1373	>	final Callable<? extends T> callable;
1374	>	T result;
1375	>	AdaptedCallable(Callable<? extends T> callable) {
1376	>	if (callable == null) throw new NullPointerException();
1377	>	this.callable = callable;
1378	>	}
1379	>	public final T getRawResult() { return result; }
1380	>	public final void setRawResult(T v) { result = v; }
1381	>	public final boolean exec() {
1382	>	try {
1383	>	result = callable.call();
1384	>	return true;
1385	>	} catch (Error err) {
1386	>	throw err;
1387	>	} catch (RuntimeException rex) {
1388	>	throw rex;
1389	>	} catch (Exception ex) {
1390	>	throw new RuntimeException(ex);
1391	>	}
1392	>	}
1393	>	public final void run() { invoke(); }
1394	>	private static final long serialVersionUID = 2838392045355241008L;
1395	>	}
1396	>
1397	>	/**
1398	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1399	>	* method of the given {@code Runnable} as its action, and returns
1400	>	* a null result upon {@link #join}.
1401	>	*
1402	>	* @param runnable the runnable action
1403	>	* @return the task
1404	>	*/
1405	>	public static ForkJoinTask<?> adapt(Runnable runnable) {
1406	>	return new AdaptedRunnableAction(runnable);
1407	>	}
1408	>
1409	>	/**
1410	>	* Returns a new {@code ForkJoinTask} that performs the {@code run}
1411	>	* method of the given {@code Runnable} as its action, and returns
1412	>	* the given result upon {@link #join}.
1413	>	*
1414	>	* @param runnable the runnable action
1415	>	* @param result the result upon completion
1416	>	* @return the task
1417	>	*/
1418	>	public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) {
1419	>	return new AdaptedRunnable<T>(runnable, result);
1420	>	}
1421	>
1422	>	/**
1423	>	* Returns a new {@code ForkJoinTask} that performs the {@code call}
1424	>	* method of the given {@code Callable} as its action, and returns
1425	>	* its result upon {@link #join}, translating any checked exceptions
1426	>	* encountered into {@code RuntimeException}.
1427	>	*
1428	>	* @param callable the callable action
1429	>	* @return the task
1430	>	*/
1431	>	public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) {
1432	>	return new AdaptedCallable<T>(callable);
1433		}
1434
1435		// Serialization support
#	Line 1003 | Line 1437 | public abstract class ForkJoinTask<V> im
1437		private static final long serialVersionUID = -7721805057305804111L;
1438
1439		/**
1440	<	* Save the state to a stream.
1440	>	* Saves this task to a stream (that is, serializes it).
1441		*
1442		* @serialData the current run status and the exception thrown
1443	<	* during execution, or null if none
1010	<	* @param s the stream
1443	>	* during execution, or {@code null} if none
1444		*/
1445		private void writeObject(java.io.ObjectOutputStream s)
1446		throws java.io.IOException {
#	Line 1016 | Line 1449 | public abstract class ForkJoinTask<V> im
1449		}
1450
1451		/**
1452	<	* Reconstitute the instance from a stream.
1020	<	*
1021	<	* @param s the stream
1452	>	* Reconstitutes this task from a stream (that is, deserializes it).
1453		*/
1454		private void readObject(java.io.ObjectInputStream s)
1455		throws java.io.IOException, ClassNotFoundException {
1456		s.defaultReadObject();
1026	–	status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts
1027	–	status |= EXTERNAL_SIGNAL; // conservatively set external signal
1457		Object ex = s.readObject();
1458		if (ex != null)
1459	<	setDoneExceptionally((Throwable)ex);
1459	>	setExceptionalCompletion((Throwable)ex);
1460		}
1461
1462	<	// Temporary Unsafe mechanics for preliminary release
1463	<	private static Unsafe getUnsafe() throws Throwable {
1462	>	// Unsafe mechanics
1463	>	private static final sun.misc.Unsafe U;
1464	>	private static final long STATUS;
1465	>
1466	>	static {
1467	>	exceptionTableLock = new ReentrantLock();
1468	>	exceptionTableRefQueue = new ReferenceQueue<Object>();
1469	>	exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY];
1470		try {
1471	<	return Unsafe.getUnsafe();
1472	<	} catch (SecurityException se) {
1473	<	try {
1474	<	return java.security.AccessController.doPrivileged
1475	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1476	<	public Unsafe run() throws Exception {
1042	<	return getUnsafePrivileged();
1043	<	}});
1044	<	} catch (java.security.PrivilegedActionException e) {
1045	<	throw e.getCause();
1046	<	}
1471	>	U = getUnsafe();
1472	>	Class<?> k = ForkJoinTask.class;
1473	>	STATUS = U.objectFieldOffset
1474	>	(k.getDeclaredField("status"));
1475	>	} catch (Exception e) {
1476	>	throw new Error(e);
1477		}
1478		}
1479
1480	<	private static Unsafe getUnsafePrivileged()
1481	<	throws NoSuchFieldException, IllegalAccessException {
1482	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1483	<	f.setAccessible(true);
1484	<	return (Unsafe) f.get(null);
1485	<	}
1486	<
1487	<	private static long fieldOffset(String fieldName)
1058	<	throws NoSuchFieldException {
1059	<	return UNSAFE.objectFieldOffset
1060	<	(ForkJoinTask.class.getDeclaredField(fieldName));
1061	<	}
1062	<
1063	<	static final Unsafe UNSAFE;
1064	<	static final long statusOffset;
1065	<
1066	<	static {
1480	>	/**
1481	>	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1482	>	* Replace with a simple call to Unsafe.getUnsafe when integrating
1483	>	* into a jdk.
1484	>	*
1485	>	* @return a sun.misc.Unsafe
1486	>	*/
1487	>	private static sun.misc.Unsafe getUnsafe() {
1488		try {
1489	<	UNSAFE = getUnsafe();
1490	<	statusOffset = fieldOffset("status");
1491	<	} catch (Throwable e) {
1492	<	throw new RuntimeException("Could not initialize intrinsics", e);
1489	>	return sun.misc.Unsafe.getUnsafe();
1490	>	} catch (SecurityException tryReflectionInstead) {}
1491	>	try {
1492	>	return java.security.AccessController.doPrivileged
1493	>	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1494	>	public sun.misc.Unsafe run() throws Exception {
1495	>	Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
1496	>	for (java.lang.reflect.Field f : k.getDeclaredFields()) {
1497	>	f.setAccessible(true);
1498	>	Object x = f.get(null);
1499	>	if (k.isInstance(x))
1500	>	return k.cast(x);
1501	>	}
1502	>	throw new NoSuchFieldError("the Unsafe");
1503	>	}});
1504	>	} catch (java.security.PrivilegedActionException e) {
1505	>	throw new RuntimeException("Could not initialize intrinsics",
1506	>	e.getCause());
1507		}
1508		}
1074	–
1509		}

Diff Legend

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