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*/ |
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package jsr166y; |
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import java.io.Serializable; |
9 |
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import java.util.*; |
8 |
> |
|
9 |
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import java.util.concurrent.*; |
10 |
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import java.util.concurrent.atomic.*; |
11 |
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import sun.misc.Unsafe; |
12 |
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import java.lang.reflect.*; |
10 |
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|
11 |
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import java.io.Serializable; |
12 |
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import java.util.Collection; |
13 |
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import java.util.Collections; |
14 |
> |
import java.util.List; |
15 |
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import java.util.RandomAccess; |
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import java.util.Map; |
17 |
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import java.util.WeakHashMap; |
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|
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/** |
20 |
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* Abstract base class for tasks that run within a {@link |
21 |
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* ForkJoinPool}. A ForkJoinTask is a thread-like entity that is much |
20 |
> |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
21 |
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* A {@code ForkJoinTask} is a thread-like entity that is much |
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* lighter weight than a normal thread. Huge numbers of tasks and |
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* subtasks may be hosted by a small number of actual threads in a |
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* ForkJoinPool, at the price of some usage limitations. |
25 |
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* |
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* <p> A "main" ForkJoinTask begins execution when submitted to a |
27 |
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* {@link ForkJoinPool}. Once started, it will usually in turn start |
28 |
< |
* other subtasks. As indicated by the name of this class, many |
29 |
< |
* programs using ForkJoinTasks employ only methods {@code fork} |
30 |
< |
* and {@code join}, or derivatives such as |
31 |
< |
* {@code invokeAll}. However, this class also provides a number |
32 |
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* of other methods that can come into play in advanced usages, as |
33 |
< |
* well as extension mechanics that allow support of new forms of |
34 |
< |
* fork/join processing. |
26 |
> |
* <p>A "main" {@code ForkJoinTask} begins execution when submitted |
27 |
> |
* to a {@link ForkJoinPool}. Once started, it will usually in turn |
28 |
> |
* start other subtasks. As indicated by the name of this class, |
29 |
> |
* many programs using {@code ForkJoinTask} employ only methods |
30 |
> |
* {@link #fork} and {@link #join}, or derivatives such as {@link |
31 |
> |
* #invokeAll}. However, this class also provides a number of other |
32 |
> |
* methods that can come into play in advanced usages, as well as |
33 |
> |
* extension mechanics that allow support of new forms of fork/join |
34 |
> |
* processing. |
35 |
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* |
36 |
< |
* <p>A ForkJoinTask is a lightweight form of {@link Future}. The |
37 |
< |
* efficiency of ForkJoinTasks stems from a set of restrictions (that |
38 |
< |
* are only partially statically enforceable) reflecting their |
39 |
< |
* intended use as computational tasks calculating pure functions or |
40 |
< |
* operating on purely isolated objects. The primary coordination |
41 |
< |
* mechanisms are {@link #fork}, that arranges asynchronous execution, |
42 |
< |
* and {@link #join}, that doesn't proceed until the task's result has |
43 |
< |
* been computed. Computations should avoid {@code synchronized} |
44 |
< |
* methods or blocks, and should minimize other blocking |
45 |
< |
* 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 IO or other external synchronization |
54 |
< |
* becomes exhausted. This usage restriction is in part enforced by |
55 |
< |
* not permitting checked exceptions such as {@code IOExceptions} |
56 |
< |
* to be 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. |
36 |
> |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
37 |
> |
* The efficiency of {@code ForkJoinTask}s stems from a set of |
38 |
> |
* restrictions (that are only partially statically enforceable) |
39 |
> |
* reflecting their intended use as computational tasks calculating |
40 |
> |
* pure functions or operating on purely isolated objects. The |
41 |
> |
* primary coordination mechanisms are {@link #fork}, that arranges |
42 |
> |
* asynchronous execution, and {@link #join}, that doesn't proceed |
43 |
> |
* until the task's result has been computed. Computations should |
44 |
> |
* avoid {@code synchronized} methods or blocks, and should minimize |
45 |
> |
* other blocking synchronization apart from joining other tasks or |
46 |
> |
* using synchronizers such as Phasers that are advertised to |
47 |
> |
* cooperate with fork/join scheduling. Tasks should also not perform |
48 |
> |
* blocking IO, and should ideally access variables that are |
49 |
> |
* completely independent of those accessed by other running |
50 |
> |
* tasks. Minor breaches of these restrictions, for example using |
51 |
> |
* shared output streams, may be tolerable in practice, but frequent |
52 |
> |
* use may result in poor performance, and the potential to |
53 |
> |
* indefinitely stall if the number of threads not waiting for IO or |
54 |
> |
* other external synchronization becomes exhausted. This usage |
55 |
> |
* restriction is in part enforced by not permitting checked |
56 |
> |
* exceptions such as {@code IOExceptions} to be thrown. However, |
57 |
> |
* computations may still encounter unchecked exceptions, that are |
58 |
> |
* rethrown to callers attempting to join them. These exceptions may |
59 |
> |
* additionally include RejectedExecutionExceptions stemming from |
60 |
> |
* internal resource exhaustion such as failure to allocate internal |
61 |
> |
* task queues. |
62 |
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* |
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* <p>The primary method for awaiting completion and extracting |
64 |
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* results of a task is {@link #join}, but there are several variants: |
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* performs the most common form of parallel invocation: forking a set |
78 |
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* of tasks and joining them all. |
79 |
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* |
80 |
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* <p> The ForkJoinTask class is not usually directly subclassed. |
80 |
> |
* <p>The ForkJoinTask class is not usually directly subclassed. |
81 |
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* Instead, you subclass one of the abstract classes that support a |
82 |
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* particular style of fork/join processing. Normally, a concrete |
82 |
> |
* particular style of fork/join processing, typically {@link |
83 |
> |
* RecursiveAction} for computations that do not return results, or |
84 |
> |
* {@link RecursiveTask} for those that do. Normally, a concrete |
85 |
|
* ForkJoinTask subclass declares fields comprising its parameters, |
86 |
|
* established in a constructor, and then defines a {@code compute} |
87 |
|
* method that somehow uses the control methods supplied by this base |
88 |
|
* class. While these methods have {@code public} access (to allow |
89 |
< |
* instances of different task subclasses to call each others |
89 |
> |
* instances of different task subclasses to call each other's |
90 |
|
* methods), some of them may only be called from within other |
91 |
< |
* ForkJoinTasks. Attempts to invoke them in other contexts result in |
92 |
< |
* exceptions or errors possibly including ClassCastException. |
91 |
> |
* ForkJoinTasks (as may be determined using method {@link |
92 |
> |
* #inForkJoinPool}). Attempts to invoke them in other contexts |
93 |
> |
* result in exceptions or errors, possibly including |
94 |
> |
* ClassCastException. |
95 |
|
* |
96 |
< |
* <p>Most base support methods are {@code final} because their |
97 |
< |
* implementations are intrinsically tied to the underlying |
98 |
< |
* lightweight task scheduling framework, and so cannot be overridden. |
99 |
< |
* Developers creating new basic styles of fork/join processing should |
100 |
< |
* minimally implement {@code protected} methods |
101 |
< |
* {@code exec}, {@code setRawResult}, and |
102 |
< |
* {@code getRawResult}, while also introducing an abstract |
103 |
< |
* computational method that can be implemented in its subclasses, |
104 |
< |
* possibly relying on other {@code protected} methods provided |
96 |
< |
* by this class. |
96 |
> |
* <p>Most base support methods are {@code final}, to prevent |
97 |
> |
* overriding of implementations that are intrinsically tied to the |
98 |
> |
* underlying lightweight task scheduling framework. Developers |
99 |
> |
* creating new basic styles of fork/join processing should minimally |
100 |
> |
* implement {@code protected} methods {@link #exec}, {@link |
101 |
> |
* #setRawResult}, and {@link #getRawResult}, while also introducing |
102 |
> |
* an abstract computational method that can be implemented in its |
103 |
> |
* subclasses, possibly relying on other {@code protected} methods |
104 |
> |
* provided by this class. |
105 |
|
* |
106 |
|
* <p>ForkJoinTasks should perform relatively small amounts of |
107 |
< |
* computations, otherwise splitting into smaller tasks. As a very |
108 |
< |
* rough rule of thumb, a task should perform more than 100 and less |
109 |
< |
* than 10000 basic computational steps. If tasks are too big, then |
110 |
< |
* parallelism cannot improve throughput. If too small, then memory |
111 |
< |
* and internal task maintenance overhead may overwhelm processing. |
107 |
> |
* computation. Large tasks should be split into smaller subtasks, |
108 |
> |
* usually via recursive decomposition. As a very rough rule of thumb, |
109 |
> |
* a task should perform more than 100 and less than 10000 basic |
110 |
> |
* computational steps. If tasks are too big, then parallelism cannot |
111 |
> |
* improve throughput. If too small, then memory and internal task |
112 |
> |
* maintenance overhead may overwhelm processing. |
113 |
|
* |
114 |
< |
* <p>ForkJoinTasks are {@code Serializable}, which enables them |
115 |
< |
* to be used in extensions such as remote execution frameworks. It is |
116 |
< |
* in general sensible to serialize tasks only before or after, but |
117 |
< |
* not during execution. Serialization is not relied on during |
118 |
< |
* execution itself. |
114 |
> |
* <p>This class provides {@code adapt} methods for {@link |
115 |
> |
* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that |
116 |
> |
* may be of use when mixing execution of ForkJoinTasks with other |
117 |
> |
* kinds of tasks. When all tasks are of this form, consider using a |
118 |
> |
* pool in {@link ForkJoinPool#setAsyncMode async mode}. |
119 |
> |
* |
120 |
> |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
121 |
> |
* used in extensions such as remote execution frameworks. It is |
122 |
> |
* sensible to serialize tasks only before or after, but not during, |
123 |
> |
* execution. Serialization is not relied on during execution itself. |
124 |
> |
* |
125 |
> |
* @since 1.7 |
126 |
> |
* @author Doug Lea |
127 |
|
*/ |
128 |
|
public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
129 |
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|
174 |
|
*/ |
175 |
|
static ForkJoinWorkerThread getWorker() { |
176 |
|
Thread t = Thread.currentThread(); |
177 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
178 |
< |
(ForkJoinWorkerThread)t : null); |
177 |
> |
return ((t instanceof ForkJoinWorkerThread) ? |
178 |
> |
(ForkJoinWorkerThread) t : null); |
179 |
|
} |
180 |
|
|
181 |
|
final boolean casStatus(int cmp, int val) { |
201 |
|
ForkJoinPool pool = getPool(); |
202 |
|
if (pool != null) { |
203 |
|
int s; // Clear signal bits while setting completion status |
204 |
< |
do;while ((s = status) >= 0 && !casStatus(s, completion)); |
204 |
> |
do {} while ((s = status) >= 0 && !casStatus(s, completion)); |
205 |
|
|
206 |
|
if ((s & SIGNAL_MASK) != 0) { |
207 |
|
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
208 |
|
pool.updateRunningCount(s); |
209 |
< |
synchronized(this) { notifyAll(); } |
209 |
> |
synchronized (this) { notifyAll(); } |
210 |
|
} |
211 |
|
} |
212 |
|
else |
219 |
|
*/ |
220 |
|
private void externallySetCompletion(int completion) { |
221 |
|
int s; |
222 |
< |
do;while ((s = status) >= 0 && |
223 |
< |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
224 |
< |
synchronized(this) { notifyAll(); } |
222 |
> |
do {} while ((s = status) >= 0 && |
223 |
> |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
224 |
> |
synchronized (this) { notifyAll(); } |
225 |
|
} |
226 |
|
|
227 |
|
/** |
228 |
< |
* Sets status to indicate normal completion |
228 |
> |
* Sets status to indicate normal completion. |
229 |
|
*/ |
230 |
|
final void setNormalCompletion() { |
231 |
|
// Try typical fast case -- single CAS, no signal, not already done. |
237 |
|
// internal waiting and notification |
238 |
|
|
239 |
|
/** |
240 |
< |
* Performs the actual monitor wait for awaitDone |
240 |
> |
* Performs the actual monitor wait for awaitDone. |
241 |
|
*/ |
242 |
|
private void doAwaitDone() { |
243 |
|
// Minimize lock bias and in/de-flation effects by maximizing |
244 |
|
// chances of waiting inside sync |
245 |
|
try { |
246 |
|
while (status >= 0) |
247 |
< |
synchronized(this) { if (status >= 0) wait(); } |
247 |
> |
synchronized (this) { if (status >= 0) wait(); } |
248 |
|
} catch (InterruptedException ie) { |
249 |
|
onInterruptedWait(); |
250 |
|
} |
251 |
|
} |
252 |
|
|
253 |
|
/** |
254 |
< |
* Performs the actual monitor wait for awaitDone |
254 |
> |
* Performs the actual timed monitor wait for awaitDone. |
255 |
|
*/ |
256 |
|
private void doAwaitDone(long startTime, long nanos) { |
257 |
< |
synchronized(this) { |
257 |
> |
synchronized (this) { |
258 |
|
try { |
259 |
|
while (status >= 0) { |
260 |
< |
long nt = nanos - System.nanoTime() - startTime; |
260 |
> |
long nt = nanos - (System.nanoTime() - startTime); |
261 |
|
if (nt <= 0) |
262 |
|
break; |
263 |
< |
wait(nt / 1000000, (int)(nt % 1000000)); |
263 |
> |
wait(nt / 1000000, (int) (nt % 1000000)); |
264 |
|
} |
265 |
|
} catch (InterruptedException ie) { |
266 |
|
onInterruptedWait(); |
276 |
|
* |
277 |
|
* @return status upon exit |
278 |
|
*/ |
279 |
< |
private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) { |
280 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
279 |
> |
private int awaitDone(ForkJoinWorkerThread w, |
280 |
> |
boolean maintainParallelism) { |
281 |
> |
ForkJoinPool pool = (w == null) ? null : w.pool; |
282 |
|
int s; |
283 |
|
while ((s = status) >= 0) { |
284 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
284 |
> |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
285 |
|
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
286 |
|
doAwaitDone(); |
287 |
|
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
294 |
|
|
295 |
|
/** |
296 |
|
* Timed version of awaitDone |
297 |
+ |
* |
298 |
|
* @return status upon exit |
299 |
|
*/ |
300 |
|
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
301 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
301 |
> |
ForkJoinPool pool = (w == null) ? null : w.pool; |
302 |
|
int s; |
303 |
|
while ((s = status) >= 0) { |
304 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
304 |
> |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
305 |
|
long startTime = System.nanoTime(); |
306 |
|
if (pool == null || !pool.preJoin(this, false)) |
307 |
|
doAwaitDone(startTime, nanos); |
323 |
|
*/ |
324 |
|
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
325 |
|
int s; |
326 |
< |
do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
326 |
> |
do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
327 |
|
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
328 |
|
pool.updateRunningCount(s); |
329 |
|
} |
378 |
|
|
379 |
|
/** |
380 |
|
* Returns result or throws exception using j.u.c.Future conventions. |
381 |
< |
* Only call when isDone known to be true. |
381 |
> |
* Only call when {@code isDone} known to be true. |
382 |
|
*/ |
383 |
|
private V reportFutureResult() |
384 |
|
throws ExecutionException, InterruptedException { |
385 |
+ |
if (Thread.interrupted()) |
386 |
+ |
throw new InterruptedException(); |
387 |
|
int s = status & COMPLETION_MASK; |
388 |
|
if (s < NORMAL) { |
389 |
|
Throwable ex; |
391 |
|
throw new CancellationException(); |
392 |
|
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
393 |
|
throw new ExecutionException(ex); |
373 |
– |
if (Thread.interrupted()) |
374 |
– |
throw new InterruptedException(); |
394 |
|
} |
395 |
|
return getRawResult(); |
396 |
|
} |
401 |
|
*/ |
402 |
|
private V reportTimedFutureResult() |
403 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
404 |
+ |
if (Thread.interrupted()) |
405 |
+ |
throw new InterruptedException(); |
406 |
|
Throwable ex; |
407 |
|
int s = status & COMPLETION_MASK; |
408 |
|
if (s == NORMAL) |
411 |
|
throw new CancellationException(); |
412 |
|
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
413 |
|
throw new ExecutionException(ex); |
393 |
– |
if (Thread.interrupted()) |
394 |
– |
throw new InterruptedException(); |
414 |
|
throw new TimeoutException(); |
415 |
|
} |
416 |
|
|
444 |
|
try { |
445 |
|
if (!exec()) |
446 |
|
return; |
447 |
< |
} catch(Throwable rex) { |
447 |
> |
} catch (Throwable rex) { |
448 |
|
setDoneExceptionally(rex); |
449 |
|
return; |
450 |
|
} |
476 |
|
final void cancelIgnoringExceptions() { |
477 |
|
try { |
478 |
|
cancel(false); |
479 |
< |
} catch(Throwable ignore) { |
479 |
> |
} catch (Throwable ignore) { |
480 |
|
} |
481 |
|
} |
482 |
|
|
488 |
|
ForkJoinTask<?> t; |
489 |
|
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
490 |
|
t.quietlyExec(); |
491 |
< |
return (s >= 0)? awaitDone(w, false) : s; // block if no work |
491 |
> |
return (s >= 0) ? awaitDone(w, false) : s; // block if no work |
492 |
|
} |
493 |
|
|
494 |
|
// public methods |
496 |
|
/** |
497 |
|
* Arranges to asynchronously execute this task. While it is not |
498 |
|
* necessarily enforced, it is a usage error to fork a task more |
499 |
< |
* than once unless it has completed and been reinitialized. This |
500 |
< |
* method may be invoked only from within ForkJoinTask |
501 |
< |
* computations. Attempts to invoke in other contexts result in |
502 |
< |
* exceptions or errors possibly including ClassCastException. |
503 |
< |
*/ |
504 |
< |
public final void fork() { |
505 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this); |
499 |
> |
* than once unless it has completed and been reinitialized. |
500 |
> |
* |
501 |
> |
* <p>This method may be invoked only from within {@code |
502 |
> |
* ForkJoinTask} computations (as may be determined using method |
503 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
504 |
> |
* result in exceptions or errors, possibly including {@code |
505 |
> |
* ClassCastException}. |
506 |
> |
* |
507 |
> |
* @return {@code this}, to simplify usage |
508 |
> |
*/ |
509 |
> |
public final ForkJoinTask<V> fork() { |
510 |
> |
((ForkJoinWorkerThread) Thread.currentThread()) |
511 |
> |
.pushTask(this); |
512 |
> |
return this; |
513 |
|
} |
514 |
|
|
515 |
|
/** |
516 |
|
* Returns the result of the computation when it is ready. |
517 |
< |
* This method differs from {@code get} in that abnormal |
518 |
< |
* completion results in RuntimeExceptions or Errors, not |
519 |
< |
* ExecutionExceptions. |
517 |
> |
* This method differs from {@link #get()} in that |
518 |
> |
* abnormal completion results in {@code RuntimeException} or |
519 |
> |
* {@code Error}, not {@code ExecutionException}. |
520 |
|
* |
521 |
|
* @return the computed result |
522 |
|
*/ |
529 |
|
|
530 |
|
/** |
531 |
|
* Commences performing this task, awaits its completion if |
532 |
< |
* necessary, and return its result. |
532 |
> |
* necessary, and return its result, or throws an (unchecked) |
533 |
> |
* exception if the underlying computation did so. |
534 |
|
* |
508 |
– |
* @throws Throwable (a RuntimeException, Error, or unchecked |
509 |
– |
* exception) if the underlying computation did so |
535 |
|
* @return the computed result |
536 |
|
*/ |
537 |
|
public final V invoke() { |
542 |
|
} |
543 |
|
|
544 |
|
/** |
545 |
< |
* Forks both tasks, returning when {@code isDone} holds for |
546 |
< |
* both of them or an exception is encountered. This method may be |
547 |
< |
* invoked only from within ForkJoinTask computations. Attempts to |
548 |
< |
* invoke in other contexts result in exceptions or errors |
549 |
< |
* possibly including ClassCastException. |
550 |
< |
* |
551 |
< |
* @param t1 one task |
552 |
< |
* @param t2 the other task |
553 |
< |
* @throws NullPointerException if t1 or t2 are null |
554 |
< |
* @throws RuntimeException or Error if either task did so |
545 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
546 |
> |
* each task or an (unchecked) exception is encountered, in which |
547 |
> |
* case the exception is rethrown. If more than one task |
548 |
> |
* encounters an exception, then this method throws any one of |
549 |
> |
* these exceptions. The individual status of each task may be |
550 |
> |
* checked using {@link #getException()} and related methods. |
551 |
> |
* |
552 |
> |
* <p>This method may be invoked only from within {@code |
553 |
> |
* ForkJoinTask} computations (as may be determined using method |
554 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
555 |
> |
* result in exceptions or errors, possibly including {@code |
556 |
> |
* ClassCastException}. |
557 |
> |
* |
558 |
> |
* @param t1 the first task |
559 |
> |
* @param t2 the second task |
560 |
> |
* @throws NullPointerException if any task is null |
561 |
|
*/ |
562 |
< |
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
562 |
> |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
563 |
|
t2.fork(); |
564 |
|
t1.invoke(); |
565 |
|
t2.join(); |
566 |
|
} |
567 |
|
|
568 |
|
/** |
569 |
< |
* Forks the given tasks, returning when {@code isDone} holds |
570 |
< |
* for all of them. If any task encounters an exception, others |
571 |
< |
* may be cancelled. This method may be invoked only from within |
572 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
573 |
< |
* result in exceptions or errors possibly including ClassCastException. |
569 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
570 |
> |
* each task or an (unchecked) exception is encountered, in which |
571 |
> |
* case the exception is rethrown. If any task encounters an |
572 |
> |
* exception, others may be, but are not guaranteed to be, |
573 |
> |
* cancelled. If more than one task encounters an exception, then |
574 |
> |
* this method throws any one of these exceptions. The individual |
575 |
> |
* status of each task may be checked using {@link #getException()} |
576 |
> |
* and related methods. |
577 |
> |
* |
578 |
> |
* <p>This method may be invoked only from within {@code |
579 |
> |
* ForkJoinTask} computations (as may be determined using method |
580 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
581 |
> |
* result in exceptions or errors, possibly including {@code |
582 |
> |
* ClassCastException}. |
583 |
|
* |
584 |
< |
* @param tasks the array of tasks |
585 |
< |
* @throws NullPointerException if tasks or any element are null |
546 |
< |
* @throws RuntimeException or Error if any task did so |
584 |
> |
* @param tasks the tasks |
585 |
> |
* @throws NullPointerException if any task is null |
586 |
|
*/ |
587 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
588 |
|
Throwable ex = null; |
618 |
|
} |
619 |
|
|
620 |
|
/** |
621 |
< |
* Forks all tasks in the collection, returning when |
622 |
< |
* {@code isDone} holds for all of them. If any task |
623 |
< |
* encounters an exception, others may be cancelled. This method |
624 |
< |
* may be invoked only from within ForkJoinTask |
625 |
< |
* computations. Attempts to invoke in other contexts result in |
626 |
< |
* exceptions or errors possibly including ClassCastException. |
621 |
> |
* Forks all tasks in the specified collection, returning when |
622 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
623 |
> |
* is encountered. If any task encounters an exception, others |
624 |
> |
* may be, but are not guaranteed to be, cancelled. If more than |
625 |
> |
* one task encounters an exception, then this method throws any |
626 |
> |
* one of these exceptions. The individual status of each task |
627 |
> |
* may be checked using {@link #getException()} and related |
628 |
> |
* methods. The behavior of this operation is undefined if the |
629 |
> |
* specified collection is modified while the operation is in |
630 |
> |
* progress. |
631 |
> |
* |
632 |
> |
* <p>This method may be invoked only from within {@code |
633 |
> |
* ForkJoinTask} computations (as may be determined using method |
634 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
635 |
> |
* result in exceptions or errors, possibly including {@code |
636 |
> |
* ClassCastException}. |
637 |
|
* |
638 |
|
* @param tasks the collection of tasks |
639 |
+ |
* @return the tasks argument, to simplify usage |
640 |
|
* @throws NullPointerException if tasks or any element are null |
591 |
– |
* @throws RuntimeException or Error if any task did so |
641 |
|
*/ |
642 |
< |
public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) { |
643 |
< |
if (!(tasks instanceof List)) { |
644 |
< |
invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()])); |
645 |
< |
return; |
642 |
> |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
643 |
> |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
644 |
> |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
645 |
> |
return tasks; |
646 |
|
} |
647 |
+ |
@SuppressWarnings("unchecked") |
648 |
|
List<? extends ForkJoinTask<?>> ts = |
649 |
< |
(List<? extends ForkJoinTask<?>>)tasks; |
649 |
> |
(List<? extends ForkJoinTask<?>>) tasks; |
650 |
|
Throwable ex = null; |
651 |
|
int last = ts.size() - 1; |
652 |
|
for (int i = last; i >= 0; --i) { |
677 |
|
} |
678 |
|
if (ex != null) |
679 |
|
rethrowException(ex); |
680 |
+ |
return tasks; |
681 |
|
} |
682 |
|
|
683 |
|
/** |
684 |
< |
* Returns true if the computation performed by this task has |
685 |
< |
* completed (or has been cancelled). |
684 |
> |
* Attempts to cancel execution of this task. This attempt will |
685 |
> |
* fail if the task has already completed, has already been |
686 |
> |
* cancelled, or could not be cancelled for some other reason. If |
687 |
> |
* successful, and this task has not started when cancel is |
688 |
> |
* called, execution of this task is suppressed, {@link |
689 |
> |
* #isCancelled} will report true, and {@link #join} will result |
690 |
> |
* in a {@code CancellationException} being thrown. |
691 |
> |
* |
692 |
> |
* <p>This method may be overridden in subclasses, but if so, must |
693 |
> |
* still ensure that these minimal properties hold. In particular, |
694 |
> |
* the {@code cancel} method itself must not throw exceptions. |
695 |
> |
* |
696 |
> |
* <p>This method is designed to be invoked by <em>other</em> |
697 |
> |
* tasks. To terminate the current task, you can just return or |
698 |
> |
* throw an unchecked exception from its computation method, or |
699 |
> |
* invoke {@link #completeExceptionally}. |
700 |
> |
* |
701 |
> |
* @param mayInterruptIfRunning this value is ignored in the |
702 |
> |
* default implementation because tasks are not |
703 |
> |
* cancelled via interruption |
704 |
|
* |
705 |
< |
* @return true if this computation has completed |
705 |
> |
* @return {@code true} if this task is now cancelled |
706 |
> |
*/ |
707 |
> |
public boolean cancel(boolean mayInterruptIfRunning) { |
708 |
> |
setCompletion(CANCELLED); |
709 |
> |
return (status & COMPLETION_MASK) == CANCELLED; |
710 |
> |
} |
711 |
> |
|
712 |
> |
/** |
713 |
> |
* Returns {@code true} if the computation performed by this task |
714 |
> |
* has completed (or has been cancelled). |
715 |
> |
* |
716 |
> |
* @return {@code true} if this computation has completed |
717 |
|
*/ |
718 |
|
public final boolean isDone() { |
719 |
|
return status < 0; |
720 |
|
} |
721 |
|
|
722 |
|
/** |
723 |
< |
* Returns true if this task was cancelled. |
723 |
> |
* Returns {@code true} if this task was cancelled. |
724 |
|
* |
725 |
< |
* @return true if this task was cancelled |
725 |
> |
* @return {@code true} if this task was cancelled |
726 |
|
*/ |
727 |
|
public final boolean isCancelled() { |
728 |
|
return (status & COMPLETION_MASK) == CANCELLED; |
729 |
|
} |
730 |
|
|
731 |
|
/** |
732 |
< |
* Asserts that the results of this task's computation will not be |
653 |
< |
* used. If a cancellation occurs before attempting to execute this |
654 |
< |
* task, then execution will be suppressed, {@code isCancelled} |
655 |
< |
* will report true, and {@code join} will result in a |
656 |
< |
* {@code CancellationException} being thrown. Otherwise, when |
657 |
< |
* cancellation races with completion, there are no guarantees |
658 |
< |
* about whether {@code isCancelled} will report true, whether |
659 |
< |
* {@code join} will return normally or via an exception, or |
660 |
< |
* whether these behaviors will remain consistent upon repeated |
661 |
< |
* invocation. |
662 |
< |
* |
663 |
< |
* <p>This method may be overridden in subclasses, but if so, must |
664 |
< |
* still ensure that these minimal properties hold. In particular, |
665 |
< |
* the cancel method itself must not throw exceptions. |
666 |
< |
* |
667 |
< |
* <p> This method is designed to be invoked by <em>other</em> |
668 |
< |
* tasks. To terminate the current task, you can just return or |
669 |
< |
* throw an unchecked exception from its computation method, or |
670 |
< |
* invoke {@code completeExceptionally}. |
732 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
733 |
|
* |
734 |
< |
* @param mayInterruptIfRunning this value is ignored in the |
735 |
< |
* default implementation because tasks are not in general |
736 |
< |
* cancelled via interruption. |
734 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
735 |
> |
*/ |
736 |
> |
public final boolean isCompletedAbnormally() { |
737 |
> |
return (status & COMPLETION_MASK) < NORMAL; |
738 |
> |
} |
739 |
> |
|
740 |
> |
/** |
741 |
> |
* Returns {@code true} if this task completed without throwing an |
742 |
> |
* exception and was not cancelled. |
743 |
|
* |
744 |
< |
* @return true if this task is now cancelled |
744 |
> |
* @return {@code true} if this task completed without throwing an |
745 |
> |
* exception and was not cancelled |
746 |
|
*/ |
747 |
< |
public boolean cancel(boolean mayInterruptIfRunning) { |
748 |
< |
setCompletion(CANCELLED); |
680 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
747 |
> |
public final boolean isCompletedNormally() { |
748 |
> |
return (status & COMPLETION_MASK) == NORMAL; |
749 |
|
} |
750 |
|
|
751 |
|
/** |
752 |
< |
* Returns true if this task threw an exception or was cancelled. |
752 |
> |
* Returns {@code true} if this task threw an exception. |
753 |
|
* |
754 |
< |
* @return true if this task threw an exception or was cancelled |
754 |
> |
* @return {@code true} if this task threw an exception |
755 |
|
*/ |
756 |
< |
public final boolean isCompletedAbnormally() { |
757 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
756 |
> |
public final boolean isCompletedExceptionally() { |
757 |
> |
return (status & COMPLETION_MASK) == EXCEPTIONAL; |
758 |
|
} |
759 |
|
|
760 |
|
/** |
761 |
|
* Returns the exception thrown by the base computation, or a |
762 |
< |
* CancellationException if cancelled, or null if none or if the |
763 |
< |
* method has not yet completed. |
762 |
> |
* {@code CancellationException} if cancelled, or {@code null} if |
763 |
> |
* none or if the method has not yet completed. |
764 |
|
* |
765 |
< |
* @return the exception, or null if none |
765 |
> |
* @return the exception, or {@code null} if none |
766 |
|
*/ |
767 |
|
public final Throwable getException() { |
768 |
|
int s = status & COMPLETION_MASK; |
779 |
|
* {@code join} and related operations. This method may be used |
780 |
|
* to induce exceptions in asynchronous tasks, or to force |
781 |
|
* completion of tasks that would not otherwise complete. Its use |
782 |
< |
* in other situations is likely to be wrong. This method is |
782 |
> |
* in other situations is discouraged. This method is |
783 |
|
* overridable, but overridden versions must invoke {@code super} |
784 |
|
* implementation to maintain guarantees. |
785 |
|
* |
789 |
|
*/ |
790 |
|
public void completeExceptionally(Throwable ex) { |
791 |
|
setDoneExceptionally((ex instanceof RuntimeException) || |
792 |
< |
(ex instanceof Error)? ex : |
792 |
> |
(ex instanceof Error) ? ex : |
793 |
|
new RuntimeException(ex)); |
794 |
|
} |
795 |
|
|
799 |
|
* operations. This method may be used to provide results for |
800 |
|
* asynchronous tasks, or to provide alternative handling for |
801 |
|
* tasks that would not otherwise complete normally. Its use in |
802 |
< |
* other situations is likely to be wrong. This method is |
802 |
> |
* other situations is discouraged. This method is |
803 |
|
* overridable, but overridden versions must invoke {@code super} |
804 |
|
* implementation to maintain guarantees. |
805 |
|
* |
808 |
|
public void complete(V value) { |
809 |
|
try { |
810 |
|
setRawResult(value); |
811 |
< |
} catch(Throwable rex) { |
811 |
> |
} catch (Throwable rex) { |
812 |
|
setDoneExceptionally(rex); |
813 |
|
return; |
814 |
|
} |
824 |
|
|
825 |
|
public final V get(long timeout, TimeUnit unit) |
826 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
827 |
+ |
long nanos = unit.toNanos(timeout); |
828 |
|
ForkJoinWorkerThread w = getWorker(); |
829 |
|
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
830 |
< |
awaitDone(w, unit.toNanos(timeout)); |
830 |
> |
awaitDone(w, nanos); |
831 |
|
return reportTimedFutureResult(); |
832 |
|
} |
833 |
|
|
838 |
|
* there are no potential dependencies between continuation of the |
839 |
|
* current task and that of any other task that might be executed |
840 |
|
* while helping. (This usually holds for pure divide-and-conquer |
841 |
< |
* tasks). This method may be invoked only from within |
842 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
843 |
< |
* result in exceptions or errors possibly including ClassCastException. |
841 |
> |
* tasks). |
842 |
> |
* |
843 |
> |
* <p>This method may be invoked only from within {@code |
844 |
> |
* ForkJoinTask} computations (as may be determined using method |
845 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
846 |
> |
* result in exceptions or errors, possibly including {@code |
847 |
> |
* ClassCastException}. |
848 |
|
* |
849 |
|
* @return the computed result |
850 |
|
*/ |
851 |
|
public final V helpJoin() { |
852 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread()); |
852 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
853 |
|
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
854 |
|
reportException(busyJoin(w)); |
855 |
|
return getRawResult(); |
857 |
|
|
858 |
|
/** |
859 |
|
* Possibly executes other tasks until this task is ready. This |
860 |
< |
* method may be invoked only from within ForkJoinTask |
861 |
< |
* computations. Attempts to invoke in other contexts result in |
862 |
< |
* exceptions or errors possibly including ClassCastException. |
860 |
> |
* method may be useful when processing collections of tasks when |
861 |
> |
* some have been cancelled or otherwise known to have aborted. |
862 |
> |
* |
863 |
> |
* <p>This method may be invoked only from within {@code |
864 |
> |
* ForkJoinTask} computations (as may be determined using method |
865 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
866 |
> |
* result in exceptions or errors, possibly including {@code |
867 |
> |
* ClassCastException}. |
868 |
|
*/ |
869 |
|
public final void quietlyHelpJoin() { |
870 |
|
if (status >= 0) { |
871 |
|
ForkJoinWorkerThread w = |
872 |
< |
(ForkJoinWorkerThread)(Thread.currentThread()); |
872 |
> |
(ForkJoinWorkerThread) Thread.currentThread(); |
873 |
|
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
874 |
|
busyJoin(w); |
875 |
|
} |
903 |
|
|
904 |
|
/** |
905 |
|
* Possibly executes tasks until the pool hosting the current task |
906 |
< |
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
907 |
< |
* designs in which many tasks are forked, but none are explicitly |
908 |
< |
* joined, instead executing them until all are processed. |
906 |
> |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
907 |
> |
* be of use in designs in which many tasks are forked, but none |
908 |
> |
* are explicitly joined, instead executing them until all are |
909 |
> |
* processed. |
910 |
> |
* |
911 |
> |
* <p>This method may be invoked only from within {@code |
912 |
> |
* ForkJoinTask} computations (as may be determined using method |
913 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
914 |
> |
* result in exceptions or errors, possibly including {@code |
915 |
> |
* ClassCastException}. |
916 |
|
*/ |
917 |
|
public static void helpQuiesce() { |
918 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())). |
919 |
< |
helpQuiescePool(); |
918 |
> |
((ForkJoinWorkerThread) Thread.currentThread()) |
919 |
> |
.helpQuiescePool(); |
920 |
|
} |
921 |
|
|
922 |
|
/** |
925 |
|
* this task, but only if reuse occurs when this task has either |
926 |
|
* never been forked, or has been forked, then completed and all |
927 |
|
* outstanding joins of this task have also completed. Effects |
928 |
< |
* under any other usage conditions are not guaranteed, and are |
929 |
< |
* almost surely wrong. This method may be useful when executing |
928 |
> |
* under any other usage conditions are not guaranteed. |
929 |
> |
* This method may be useful when executing |
930 |
|
* pre-constructed trees of subtasks in loops. |
931 |
|
*/ |
932 |
|
public void reinitialize() { |
937 |
|
|
938 |
|
/** |
939 |
|
* Returns the pool hosting the current task execution, or null |
940 |
< |
* if this task is executing outside of any pool. |
940 |
> |
* if this task is executing outside of any ForkJoinPool. |
941 |
|
* |
942 |
< |
* @return the pool, or null if none |
942 |
> |
* @see #inForkJoinPool |
943 |
> |
* @return the pool, or {@code null} if none |
944 |
|
*/ |
945 |
|
public static ForkJoinPool getPool() { |
946 |
|
Thread t = Thread.currentThread(); |
947 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
948 |
< |
((ForkJoinWorkerThread)t).pool : null); |
947 |
> |
return (t instanceof ForkJoinWorkerThread) ? |
948 |
> |
((ForkJoinWorkerThread) t).pool : null; |
949 |
> |
} |
950 |
> |
|
951 |
> |
/** |
952 |
> |
* Returns {@code true} if the current thread is executing as a |
953 |
> |
* ForkJoinPool computation. |
954 |
> |
* |
955 |
> |
* @return {@code true} if the current thread is executing as a |
956 |
> |
* ForkJoinPool computation, or false otherwise |
957 |
> |
*/ |
958 |
> |
public static boolean inForkJoinPool() { |
959 |
> |
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
960 |
|
} |
961 |
|
|
962 |
|
/** |
965 |
|
* by the current thread, and has not commenced executing in |
966 |
|
* another thread. This method may be useful when arranging |
967 |
|
* alternative local processing of tasks that could have been, but |
968 |
< |
* were not, stolen. This method may be invoked only from within |
872 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
873 |
< |
* result in exceptions or errors possibly including ClassCastException. |
968 |
> |
* were not, stolen. |
969 |
|
* |
970 |
< |
* @return true if unforked |
970 |
> |
* <p>This method may be invoked only from within {@code |
971 |
> |
* ForkJoinTask} computations (as may be determined using method |
972 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
973 |
> |
* result in exceptions or errors, possibly including {@code |
974 |
> |
* ClassCastException}. |
975 |
> |
* |
976 |
> |
* @return {@code true} if unforked |
977 |
|
*/ |
978 |
|
public boolean tryUnfork() { |
979 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this); |
979 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
980 |
> |
.unpushTask(this); |
981 |
|
} |
982 |
|
|
983 |
|
/** |
986 |
|
* value may be useful for heuristic decisions about whether to |
987 |
|
* fork other tasks. |
988 |
|
* |
989 |
+ |
* <p>This method may be invoked only from within {@code |
990 |
+ |
* ForkJoinTask} computations (as may be determined using method |
991 |
+ |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
992 |
+ |
* result in exceptions or errors, possibly including {@code |
993 |
+ |
* ClassCastException}. |
994 |
+ |
* |
995 |
|
* @return the number of tasks |
996 |
|
*/ |
997 |
|
public static int getQueuedTaskCount() { |
998 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
999 |
< |
getQueueSize(); |
998 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
999 |
> |
.getQueueSize(); |
1000 |
|
} |
1001 |
|
|
1002 |
|
/** |
1009 |
|
* tasks, and to process computations locally if this threshold is |
1010 |
|
* exceeded. |
1011 |
|
* |
1012 |
+ |
* <p>This method may be invoked only from within {@code |
1013 |
+ |
* ForkJoinTask} computations (as may be determined using method |
1014 |
+ |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1015 |
+ |
* result in exceptions or errors, possibly including {@code |
1016 |
+ |
* ClassCastException}. |
1017 |
+ |
* |
1018 |
|
* @return the surplus number of tasks, which may be negative |
1019 |
|
*/ |
1020 |
|
public static int getSurplusQueuedTaskCount() { |
1021 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())) |
1021 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1022 |
|
.getEstimatedSurplusTaskCount(); |
1023 |
|
} |
1024 |
|
|
1025 |
|
// Extension methods |
1026 |
|
|
1027 |
|
/** |
1028 |
< |
* Returns the result that would be returned by {@code join}, |
1029 |
< |
* even if this task completed abnormally, or null if this task is |
1030 |
< |
* not known to have been completed. This method is designed to |
1031 |
< |
* aid debugging, as well as to support extensions. Its use in any |
1032 |
< |
* other context is discouraged. |
1028 |
> |
* Returns the result that would be returned by {@link #join}, even |
1029 |
> |
* if this task completed abnormally, or {@code null} if this task |
1030 |
> |
* is not known to have been completed. This method is designed |
1031 |
> |
* to aid debugging, as well as to support extensions. Its use in |
1032 |
> |
* any other context is discouraged. |
1033 |
|
* |
1034 |
< |
* @return the result, or null if not completed |
1034 |
> |
* @return the result, or {@code null} if not completed |
1035 |
|
*/ |
1036 |
|
public abstract V getRawResult(); |
1037 |
|
|
1050 |
|
* called otherwise. The return value controls whether this task |
1051 |
|
* is considered to be done normally. It may return false in |
1052 |
|
* asynchronous actions that require explicit invocations of |
1053 |
< |
* {@code complete} to become joinable. It may throw exceptions |
1054 |
< |
* to indicate abnormal exit. |
1053 |
> |
* {@link #complete} to become joinable. It may also throw an |
1054 |
> |
* (unchecked) exception to indicate abnormal exit. |
1055 |
|
* |
1056 |
< |
* @return true if completed normally |
943 |
< |
* @throws Error or RuntimeException if encountered during computation |
1056 |
> |
* @return {@code true} if completed normally |
1057 |
|
*/ |
1058 |
|
protected abstract boolean exec(); |
1059 |
|
|
1060 |
|
/** |
1061 |
< |
* Returns, but does not unschedule or execute, the task queued by |
1062 |
< |
* the current thread but not yet executed, if one is |
1061 |
> |
* Returns, but does not unschedule or execute, a task queued by |
1062 |
> |
* the current thread but not yet executed, if one is immediately |
1063 |
|
* available. There is no guarantee that this task will actually |
1064 |
< |
* be polled or executed next. This method is designed primarily |
1065 |
< |
* to support extensions, and is unlikely to be useful otherwise. |
1066 |
< |
* This method may be invoked only from within ForkJoinTask |
1067 |
< |
* computations. Attempts to invoke in other contexts result in |
1068 |
< |
* exceptions or errors possibly including ClassCastException. |
1064 |
> |
* be polled or executed next. Conversely, this method may return |
1065 |
> |
* null even if a task exists but cannot be accessed without |
1066 |
> |
* contention with other threads. This method is designed |
1067 |
> |
* primarily to support extensions, and is unlikely to be useful |
1068 |
> |
* otherwise. |
1069 |
|
* |
1070 |
< |
* @return the next task, or null if none are available |
1070 |
> |
* <p>This method may be invoked only from within {@code |
1071 |
> |
* ForkJoinTask} computations (as may be determined using method |
1072 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1073 |
> |
* result in exceptions or errors, possibly including {@code |
1074 |
> |
* ClassCastException}. |
1075 |
> |
* |
1076 |
> |
* @return the next task, or {@code null} if none are available |
1077 |
|
*/ |
1078 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1079 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask(); |
1079 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1080 |
> |
.peekTask(); |
1081 |
|
} |
1082 |
|
|
1083 |
|
/** |
1084 |
|
* Unschedules and returns, without executing, the next task |
1085 |
|
* queued by the current thread but not yet executed. This method |
1086 |
|
* is designed primarily to support extensions, and is unlikely to |
1087 |
< |
* be useful otherwise. This method may be invoked only from |
1088 |
< |
* within ForkJoinTask computations. Attempts to invoke in other |
1089 |
< |
* contexts result in exceptions or errors possibly including |
1090 |
< |
* ClassCastException. |
1087 |
> |
* be useful otherwise. |
1088 |
> |
* |
1089 |
> |
* <p>This method may be invoked only from within {@code |
1090 |
> |
* ForkJoinTask} computations (as may be determined using method |
1091 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1092 |
> |
* result in exceptions or errors, possibly including {@code |
1093 |
> |
* ClassCastException}. |
1094 |
|
* |
1095 |
< |
* @return the next task, or null if none are available |
1095 |
> |
* @return the next task, or {@code null} if none are available |
1096 |
|
*/ |
1097 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1098 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask(); |
1098 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1099 |
> |
.pollLocalTask(); |
1100 |
|
} |
1101 |
|
|
1102 |
|
/** |
1107 |
|
* {@code null} result does not necessarily imply quiescence |
1108 |
|
* of the pool this task is operating in. This method is designed |
1109 |
|
* primarily to support extensions, and is unlikely to be useful |
1110 |
< |
* otherwise. This method may be invoked only from within |
987 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
988 |
< |
* result in exceptions or errors possibly including |
989 |
< |
* ClassCastException. |
1110 |
> |
* otherwise. |
1111 |
|
* |
1112 |
< |
* @return a task, or null if none are available |
1112 |
> |
* <p>This method may be invoked only from within {@code |
1113 |
> |
* ForkJoinTask} computations (as may be determined using method |
1114 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1115 |
> |
* result in exceptions or errors, possibly including {@code |
1116 |
> |
* ClassCastException}. |
1117 |
> |
* |
1118 |
> |
* @return a task, or {@code null} if none are available |
1119 |
|
*/ |
1120 |
|
protected static ForkJoinTask<?> pollTask() { |
1121 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1122 |
< |
pollTask(); |
1121 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1122 |
> |
.pollTask(); |
1123 |
> |
} |
1124 |
> |
|
1125 |
> |
/** |
1126 |
> |
* Adaptor for Runnables. This implements RunnableFuture |
1127 |
> |
* to be compliant with AbstractExecutorService constraints |
1128 |
> |
* when used in ForkJoinPool. |
1129 |
> |
*/ |
1130 |
> |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1131 |
> |
implements RunnableFuture<T> { |
1132 |
> |
final Runnable runnable; |
1133 |
> |
final T resultOnCompletion; |
1134 |
> |
T result; |
1135 |
> |
AdaptedRunnable(Runnable runnable, T result) { |
1136 |
> |
if (runnable == null) throw new NullPointerException(); |
1137 |
> |
this.runnable = runnable; |
1138 |
> |
this.resultOnCompletion = result; |
1139 |
> |
} |
1140 |
> |
public T getRawResult() { return result; } |
1141 |
> |
public void setRawResult(T v) { result = v; } |
1142 |
> |
public boolean exec() { |
1143 |
> |
runnable.run(); |
1144 |
> |
result = resultOnCompletion; |
1145 |
> |
return true; |
1146 |
> |
} |
1147 |
> |
public void run() { invoke(); } |
1148 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1149 |
> |
} |
1150 |
> |
|
1151 |
> |
/** |
1152 |
> |
* Adaptor for Callables |
1153 |
> |
*/ |
1154 |
> |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1155 |
> |
implements RunnableFuture<T> { |
1156 |
> |
final Callable<? extends T> callable; |
1157 |
> |
T result; |
1158 |
> |
AdaptedCallable(Callable<? extends T> callable) { |
1159 |
> |
if (callable == null) throw new NullPointerException(); |
1160 |
> |
this.callable = callable; |
1161 |
> |
} |
1162 |
> |
public T getRawResult() { return result; } |
1163 |
> |
public void setRawResult(T v) { result = v; } |
1164 |
> |
public boolean exec() { |
1165 |
> |
try { |
1166 |
> |
result = callable.call(); |
1167 |
> |
return true; |
1168 |
> |
} catch (Error err) { |
1169 |
> |
throw err; |
1170 |
> |
} catch (RuntimeException rex) { |
1171 |
> |
throw rex; |
1172 |
> |
} catch (Exception ex) { |
1173 |
> |
throw new RuntimeException(ex); |
1174 |
> |
} |
1175 |
> |
} |
1176 |
> |
public void run() { invoke(); } |
1177 |
> |
private static final long serialVersionUID = 2838392045355241008L; |
1178 |
> |
} |
1179 |
> |
|
1180 |
> |
/** |
1181 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1182 |
> |
* method of the given {@code Runnable} as its action, and returns |
1183 |
> |
* a null result upon {@link #join}. |
1184 |
> |
* |
1185 |
> |
* @param runnable the runnable action |
1186 |
> |
* @return the task |
1187 |
> |
*/ |
1188 |
> |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1189 |
> |
return new AdaptedRunnable<Void>(runnable, null); |
1190 |
> |
} |
1191 |
> |
|
1192 |
> |
/** |
1193 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1194 |
> |
* method of the given {@code Runnable} as its action, and returns |
1195 |
> |
* the given result upon {@link #join}. |
1196 |
> |
* |
1197 |
> |
* @param runnable the runnable action |
1198 |
> |
* @param result the result upon completion |
1199 |
> |
* @return the task |
1200 |
> |
*/ |
1201 |
> |
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1202 |
> |
return new AdaptedRunnable<T>(runnable, result); |
1203 |
> |
} |
1204 |
> |
|
1205 |
> |
/** |
1206 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1207 |
> |
* method of the given {@code Callable} as its action, and returns |
1208 |
> |
* its result upon {@link #join}, translating any checked exceptions |
1209 |
> |
* encountered into {@code RuntimeException}. |
1210 |
> |
* |
1211 |
> |
* @param callable the callable action |
1212 |
> |
* @return the task |
1213 |
> |
*/ |
1214 |
> |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1215 |
> |
return new AdaptedCallable<T>(callable); |
1216 |
|
} |
1217 |
|
|
1218 |
|
// Serialization support |
1223 |
|
* Save the state to a stream. |
1224 |
|
* |
1225 |
|
* @serialData the current run status and the exception thrown |
1226 |
< |
* during execution, or null if none |
1226 |
> |
* during execution, or {@code null} if none |
1227 |
|
* @param s the stream |
1228 |
|
*/ |
1229 |
|
private void writeObject(java.io.ObjectOutputStream s) |
1244 |
|
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1245 |
|
Object ex = s.readObject(); |
1246 |
|
if (ex != null) |
1247 |
< |
setDoneExceptionally((Throwable)ex); |
1247 |
> |
setDoneExceptionally((Throwable) ex); |
1248 |
|
} |
1249 |
|
|
1250 |
< |
// Temporary Unsafe mechanics for preliminary release |
1251 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1250 |
> |
// Unsafe mechanics |
1251 |
> |
|
1252 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1253 |
> |
private static final long statusOffset = |
1254 |
> |
objectFieldOffset("status", ForkJoinTask.class); |
1255 |
> |
|
1256 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1257 |
|
try { |
1258 |
< |
return Unsafe.getUnsafe(); |
1258 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1259 |
> |
} catch (NoSuchFieldException e) { |
1260 |
> |
// Convert Exception to corresponding Error |
1261 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1262 |
> |
error.initCause(e); |
1263 |
> |
throw error; |
1264 |
> |
} |
1265 |
> |
} |
1266 |
> |
|
1267 |
> |
/** |
1268 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1269 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1270 |
> |
* into a jdk. |
1271 |
> |
* |
1272 |
> |
* @return a sun.misc.Unsafe |
1273 |
> |
*/ |
1274 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1275 |
> |
try { |
1276 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1277 |
|
} catch (SecurityException se) { |
1278 |
|
try { |
1279 |
|
return java.security.AccessController.doPrivileged |
1280 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1281 |
< |
public Unsafe run() throws Exception { |
1282 |
< |
return getUnsafePrivileged(); |
1280 |
> |
(new java.security |
1281 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1282 |
> |
public sun.misc.Unsafe run() throws Exception { |
1283 |
> |
java.lang.reflect.Field f = sun.misc |
1284 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1285 |
> |
f.setAccessible(true); |
1286 |
> |
return (sun.misc.Unsafe) f.get(null); |
1287 |
|
}}); |
1288 |
|
} catch (java.security.PrivilegedActionException e) { |
1289 |
< |
throw e.getCause(); |
1289 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1290 |
> |
e.getCause()); |
1291 |
|
} |
1292 |
|
} |
1293 |
|
} |
1046 |
– |
|
1047 |
– |
private static Unsafe getUnsafePrivileged() |
1048 |
– |
throws NoSuchFieldException, IllegalAccessException { |
1049 |
– |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1050 |
– |
f.setAccessible(true); |
1051 |
– |
return (Unsafe) f.get(null); |
1052 |
– |
} |
1053 |
– |
|
1054 |
– |
private static long fieldOffset(String fieldName) |
1055 |
– |
throws NoSuchFieldException { |
1056 |
– |
return UNSAFE.objectFieldOffset |
1057 |
– |
(ForkJoinTask.class.getDeclaredField(fieldName)); |
1058 |
– |
} |
1059 |
– |
|
1060 |
– |
static final Unsafe UNSAFE; |
1061 |
– |
static final long statusOffset; |
1062 |
– |
|
1063 |
– |
static { |
1064 |
– |
try { |
1065 |
– |
UNSAFE = getUnsafe(); |
1066 |
– |
statusOffset = fieldOffset("status"); |
1067 |
– |
} catch (Throwable e) { |
1068 |
– |
throw new RuntimeException("Could not initialize intrinsics", e); |
1069 |
– |
} |
1070 |
– |
} |
1071 |
– |
|
1294 |
|
} |