64 |
|
* results of a task is {@link #join}, but there are several variants: |
65 |
|
* The {@link Future#get} methods support interruptible and/or timed |
66 |
|
* waits for completion and report results using {@code Future} |
67 |
< |
* conventions. Method {@link #helpJoin} enables callers to actively |
68 |
< |
* execute other tasks while awaiting joins, which is sometimes more |
69 |
< |
* efficient but only applies when all subtasks are known to be |
70 |
< |
* strictly tree-structured. Method {@link #invoke} is semantically |
67 |
> |
* conventions. Method {@link #invoke} is semantically |
68 |
|
* equivalent to {@code fork(); join()} but always attempts to begin |
69 |
|
* execution in the current thread. The "<em>quiet</em>" forms of |
70 |
|
* these methods do not extract results or report exceptions. These |
100 |
|
* ForkJoinTasks (as may be determined using method {@link |
101 |
|
* #inForkJoinPool}). Attempts to invoke them in other contexts |
102 |
|
* result in exceptions or errors, possibly including |
103 |
< |
* ClassCastException. |
103 |
> |
* {@code ClassCastException}. |
104 |
|
* |
105 |
|
* <p>Most base support methods are {@code final}, to prevent |
106 |
|
* overriding of implementations that are intrinsically tied to the |
122 |
|
* |
123 |
|
* <p>This class provides {@code adapt} methods for {@link Runnable} |
124 |
|
* and {@link Callable}, that may be of use when mixing execution of |
125 |
< |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks |
126 |
< |
* are of this form, consider using a pool in |
130 |
< |
* {@linkplain ForkJoinPool#setAsyncMode async mode}. |
125 |
> |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
126 |
> |
* of this form, consider using a pool constructed in <em>asyncMode</em>. |
127 |
|
* |
128 |
|
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
129 |
|
* used in extensions such as remote execution frameworks. It is |
144 |
|
* status maintenance (2) execution and awaiting completion (3) |
145 |
|
* user-level methods that additionally report results. This is |
146 |
|
* sometimes hard to see because this file orders exported methods |
147 |
< |
* in a way that flows well in javadocs. |
147 |
> |
* in a way that flows well in javadocs. In particular, most |
148 |
> |
* join mechanics are in method quietlyJoin, below. |
149 |
|
*/ |
150 |
|
|
151 |
< |
/** |
152 |
< |
* Run control status bits packed into a single int to minimize |
153 |
< |
* footprint and to ensure atomicity (via CAS). Status is |
154 |
< |
* initially zero, and takes on nonnegative values until |
155 |
< |
* completed, upon which status holds COMPLETED. CANCELLED, or |
156 |
< |
* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
157 |
< |
* blocking waits by other threads have the SIGNAL bit set. |
158 |
< |
* |
159 |
< |
* Completion of a stolen task with SIGNAL set awakens any waiters |
163 |
< |
* via notifyAll. Even though suboptimal for some purposes, we use |
151 |
> |
/* |
152 |
> |
* The status field holds run control status bits packed into a |
153 |
> |
* single int to minimize footprint and to ensure atomicity (via |
154 |
> |
* CAS). Status is initially zero, and takes on nonnegative |
155 |
> |
* values until completed, upon which status holds value |
156 |
> |
* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
157 |
> |
* waits by other threads have the SIGNAL bit set. Completion of |
158 |
> |
* a stolen task with SIGNAL set awakens any waiters via |
159 |
> |
* notifyAll. Even though suboptimal for some purposes, we use |
160 |
|
* basic builtin wait/notify to take advantage of "monitor |
161 |
|
* inflation" in JVMs that we would otherwise need to emulate to |
162 |
|
* avoid adding further per-task bookkeeping overhead. We want |
163 |
|
* these monitors to be "fat", i.e., not use biasing or thin-lock |
164 |
|
* techniques, so use some odd coding idioms that tend to avoid |
165 |
|
* them. |
170 |
– |
* |
171 |
– |
* Note that bits 1-28 are currently unused. Also value |
172 |
– |
* 0x80000000 is available as spare completion value. |
166 |
|
*/ |
167 |
+ |
|
168 |
+ |
/** The run status of this task */ |
169 |
|
volatile int status; // accessed directly by pool and workers |
170 |
|
|
171 |
< |
private static final int COMPLETION_MASK = 0xe0000000; |
172 |
< |
private static final int NORMAL = 0xe0000000; // == mask |
173 |
< |
private static final int CANCELLED = 0xc0000000; |
174 |
< |
private static final int EXCEPTIONAL = 0xa0000000; |
180 |
< |
private static final int SIGNAL = 0x00000001; |
171 |
> |
private static final int NORMAL = -1; |
172 |
> |
private static final int CANCELLED = -2; |
173 |
> |
private static final int EXCEPTIONAL = -3; |
174 |
> |
private static final int SIGNAL = 1; |
175 |
|
|
176 |
|
/** |
177 |
|
* Table of exceptions thrown by tasks, to enable reporting by |
192 |
|
* also clearing signal request bits. |
193 |
|
* |
194 |
|
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
201 |
– |
* @return status on exit |
195 |
|
*/ |
196 |
< |
private int setCompletion(int completion) { |
196 |
> |
private void setCompletion(int completion) { |
197 |
|
int s; |
198 |
|
while ((s = status) >= 0) { |
199 |
|
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) { |
200 |
< |
if ((s & SIGNAL) != 0) |
200 |
> |
if (s != 0) |
201 |
|
synchronized (this) { notifyAll(); } |
202 |
< |
return completion; |
202 |
> |
break; |
203 |
|
} |
204 |
|
} |
212 |
– |
return s; |
205 |
|
} |
206 |
|
|
207 |
|
/** |
208 |
< |
* Record exception and set exceptional completion |
208 |
> |
* Records exception and sets exceptional completion. |
209 |
> |
* |
210 |
|
* @return status on exit |
211 |
|
*/ |
212 |
< |
private int setExceptionalCompletion(Throwable rex) { |
212 |
> |
private void setExceptionalCompletion(Throwable rex) { |
213 |
|
exceptionMap.put(this, rex); |
214 |
< |
return setCompletion(EXCEPTIONAL); |
214 |
> |
setCompletion(EXCEPTIONAL); |
215 |
|
} |
216 |
|
|
217 |
|
/** |
218 |
< |
* Blocks a worker thread until completion. Called only by pool. |
218 |
> |
* Blocks a worker thread until completion. Called only by |
219 |
> |
* pool. Currently unused -- pool-based waits use timeout |
220 |
> |
* version below. |
221 |
|
*/ |
222 |
|
final void internalAwaitDone() { |
223 |
< |
int s; |
223 |
> |
int s; // the odd construction reduces lock bias effects |
224 |
|
while ((s = status) >= 0) { |
225 |
< |
synchronized(this) { |
226 |
< |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){ |
227 |
< |
do { |
228 |
< |
try { |
234 |
< |
wait(); |
235 |
< |
} catch (InterruptedException ie) { |
236 |
< |
cancelIfTerminating(); |
237 |
< |
} |
238 |
< |
} while (status >= 0); |
239 |
< |
break; |
225 |
> |
try { |
226 |
> |
synchronized(this) { |
227 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
228 |
> |
wait(); |
229 |
|
} |
230 |
+ |
} catch (InterruptedException ie) { |
231 |
+ |
cancelIfTerminating(); |
232 |
|
} |
233 |
|
} |
234 |
|
} |
235 |
|
|
236 |
|
/** |
237 |
< |
* Blocks a non-worker-thread until completion. |
237 |
> |
* Blocks a worker thread until completed or timed out. Called |
238 |
> |
* only by pool. |
239 |
> |
* |
240 |
|
* @return status on exit |
241 |
|
*/ |
242 |
< |
private int externalAwaitDone() { |
242 |
> |
final int internalAwaitDone(long millis) { |
243 |
> |
int s; |
244 |
> |
if ((s = status) >= 0) { |
245 |
> |
try { |
246 |
> |
synchronized(this) { |
247 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
248 |
> |
wait(millis, 0); |
249 |
> |
} |
250 |
> |
} catch (InterruptedException ie) { |
251 |
> |
cancelIfTerminating(); |
252 |
> |
} |
253 |
> |
s = status; |
254 |
> |
} |
255 |
> |
return s; |
256 |
> |
} |
257 |
> |
|
258 |
> |
/** |
259 |
> |
* Blocks a non-worker-thread until completion. |
260 |
> |
*/ |
261 |
> |
private void externalAwaitDone() { |
262 |
|
int s; |
263 |
|
while ((s = status) >= 0) { |
264 |
|
synchronized(this) { |
265 |
< |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, s|SIGNAL)){ |
265 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){ |
266 |
|
boolean interrupted = false; |
267 |
< |
do { |
267 |
> |
while (status >= 0) { |
268 |
|
try { |
269 |
|
wait(); |
270 |
|
} catch (InterruptedException ie) { |
271 |
|
interrupted = true; |
272 |
|
} |
273 |
< |
} while ((s = status) >= 0); |
273 |
> |
} |
274 |
|
if (interrupted) |
275 |
|
Thread.currentThread().interrupt(); |
276 |
|
break; |
277 |
|
} |
278 |
|
} |
279 |
|
} |
268 |
– |
return s; |
280 |
|
} |
281 |
|
|
282 |
|
/** |
283 |
|
* Unless done, calls exec and records status if completed, but |
284 |
< |
* doesn't wait for completion otherwise. |
284 |
> |
* doesn't wait for completion otherwise. Primary execution method |
285 |
> |
* for ForkJoinWorkerThread. |
286 |
|
*/ |
287 |
< |
final void tryExec() { |
287 |
> |
final void quietlyExec() { |
288 |
|
try { |
289 |
|
if (status < 0 || !exec()) |
290 |
|
return; |
295 |
|
setCompletion(NORMAL); // must be outside try block |
296 |
|
} |
297 |
|
|
286 |
– |
/** |
287 |
– |
* If not done and this task is next in worker queue, runs it, |
288 |
– |
* else waits for it. |
289 |
– |
* @return status on exit |
290 |
– |
*/ |
291 |
– |
private int waitingJoin() { |
292 |
– |
int s = status; |
293 |
– |
if (s < 0) |
294 |
– |
return s; |
295 |
– |
Thread t = Thread.currentThread(); |
296 |
– |
if (t instanceof ForkJoinWorkerThread) { |
297 |
– |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
298 |
– |
if (w.unpushTask(this)) { |
299 |
– |
boolean completed; |
300 |
– |
try { |
301 |
– |
completed = exec(); |
302 |
– |
} catch (Throwable rex) { |
303 |
– |
return setExceptionalCompletion(rex); |
304 |
– |
} |
305 |
– |
if (completed) |
306 |
– |
return setCompletion(NORMAL); |
307 |
– |
} |
308 |
– |
return w.pool.awaitJoin(this); |
309 |
– |
} |
310 |
– |
else |
311 |
– |
return externalAwaitDone(); |
312 |
– |
} |
313 |
– |
|
314 |
– |
/** |
315 |
– |
* Unless done, calls exec and records status if completed, or |
316 |
– |
* waits for completion otherwise. |
317 |
– |
* @return status on exit |
318 |
– |
*/ |
319 |
– |
private int waitingInvoke() { |
320 |
– |
int s = status; |
321 |
– |
if (s < 0) |
322 |
– |
return s; |
323 |
– |
boolean completed; |
324 |
– |
try { |
325 |
– |
completed = exec(); |
326 |
– |
} catch (Throwable rex) { |
327 |
– |
return setExceptionalCompletion(rex); |
328 |
– |
} |
329 |
– |
if (completed) |
330 |
– |
return setCompletion(NORMAL); |
331 |
– |
return waitingJoin(); |
332 |
– |
} |
333 |
– |
|
334 |
– |
/** |
335 |
– |
* If this task is next in worker queue, runs it, else processes other |
336 |
– |
* tasks until complete. |
337 |
– |
* @return status on exit |
338 |
– |
*/ |
339 |
– |
private int busyJoin() { |
340 |
– |
int s = status; |
341 |
– |
if (s < 0) |
342 |
– |
return s; |
343 |
– |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
344 |
– |
if (w.unpushTask(this)) { |
345 |
– |
boolean completed; |
346 |
– |
try { |
347 |
– |
completed = exec(); |
348 |
– |
} catch (Throwable rex) { |
349 |
– |
return setExceptionalCompletion(rex); |
350 |
– |
} |
351 |
– |
if (completed) |
352 |
– |
return setCompletion(NORMAL); |
353 |
– |
} |
354 |
– |
return w.execWhileJoining(this); |
355 |
– |
} |
356 |
– |
|
357 |
– |
/** |
358 |
– |
* Returns result or throws exception associated with given status. |
359 |
– |
* @param s the status |
360 |
– |
*/ |
361 |
– |
private V reportResult(int s) { |
362 |
– |
Throwable ex; |
363 |
– |
if (s < NORMAL && (ex = getException()) != null) |
364 |
– |
UNSAFE.throwException(ex); |
365 |
– |
return getRawResult(); |
366 |
– |
} |
367 |
– |
|
298 |
|
// public methods |
299 |
|
|
300 |
|
/** |
330 |
|
* @return the computed result |
331 |
|
*/ |
332 |
|
public final V join() { |
333 |
< |
return reportResult(waitingJoin()); |
333 |
> |
quietlyJoin(); |
334 |
> |
Throwable ex; |
335 |
> |
if (status < NORMAL && (ex = getException()) != null) |
336 |
> |
UNSAFE.throwException(ex); |
337 |
> |
return getRawResult(); |
338 |
|
} |
339 |
|
|
340 |
|
/** |
341 |
|
* Commences performing this task, awaits its completion if |
342 |
< |
* necessary, and return its result, or throws an (unchecked) |
343 |
< |
* exception if the underlying computation did so. |
342 |
> |
* necessary, and returns its result, or throws an (unchecked) |
343 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
344 |
> |
* computation did so. |
345 |
|
* |
346 |
|
* @return the computed result |
347 |
|
*/ |
348 |
|
public final V invoke() { |
349 |
< |
return reportResult(waitingInvoke()); |
349 |
> |
quietlyInvoke(); |
350 |
> |
Throwable ex; |
351 |
> |
if (status < NORMAL && (ex = getException()) != null) |
352 |
> |
UNSAFE.throwException(ex); |
353 |
> |
return getRawResult(); |
354 |
|
} |
355 |
|
|
356 |
|
/** |
357 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
358 |
|
* each task or an (unchecked) exception is encountered, in which |
359 |
< |
* case the exception is rethrown. If either task encounters an |
360 |
< |
* exception, the other one may be, but is not guaranteed to be, |
361 |
< |
* cancelled. If both tasks throw an exception, then this method |
362 |
< |
* throws one of them. The individual status of each task may be |
363 |
< |
* checked using {@link #getException()} and related methods. |
359 |
> |
* case the exception is rethrown. If more than one task |
360 |
> |
* encounters an exception, then this method throws any one of |
361 |
> |
* these exceptions. If any task encounters an exception, the |
362 |
> |
* other may be cancelled. However, the execution status of |
363 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
364 |
> |
* status of each task may be obtained using {@link |
365 |
> |
* #getException()} and related methods to check if they have been |
366 |
> |
* cancelled, completed normally or exceptionally, or left |
367 |
> |
* unprocessed. |
368 |
|
* |
369 |
|
* <p>This method may be invoked only from within {@code |
370 |
|
* ForkJoinTask} computations (as may be determined using method |
385 |
|
/** |
386 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
387 |
|
* each task or an (unchecked) exception is encountered, in which |
388 |
< |
* case the exception is rethrown. If any task encounters an |
389 |
< |
* exception, others may be, but are not guaranteed to be, |
390 |
< |
* cancelled. If more than one task encounters an exception, then |
391 |
< |
* this method throws any one of these exceptions. The individual |
392 |
< |
* status of each task may be checked using {@link #getException()} |
393 |
< |
* and related methods. |
388 |
> |
* case the exception is rethrown. If more than one task |
389 |
> |
* encounters an exception, then this method throws any one of |
390 |
> |
* these exceptions. If any task encounters an exception, others |
391 |
> |
* may be cancelled. However, the execution status of individual |
392 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
393 |
> |
* each task may be obtained using {@link #getException()} and |
394 |
> |
* related methods to check if they have been cancelled, completed |
395 |
> |
* normally or exceptionally, or left unprocessed. |
396 |
|
* |
397 |
|
* <p>This method may be invoked only from within {@code |
398 |
|
* ForkJoinTask} computations (as may be determined using method |
414 |
|
} |
415 |
|
else if (i != 0) |
416 |
|
t.fork(); |
417 |
< |
else if (t.waitingInvoke() < NORMAL && ex == null) |
418 |
< |
ex = t.getException(); |
417 |
> |
else { |
418 |
> |
t.quietlyInvoke(); |
419 |
> |
if (ex == null && t.status < NORMAL) |
420 |
> |
ex = t.getException(); |
421 |
> |
} |
422 |
|
} |
423 |
|
for (int i = 1; i <= last; ++i) { |
424 |
|
ForkJoinTask<?> t = tasks[i]; |
425 |
|
if (t != null) { |
426 |
|
if (ex != null) |
427 |
|
t.cancel(false); |
428 |
< |
else if (t.waitingJoin() < NORMAL && ex == null) |
429 |
< |
ex = t.getException(); |
428 |
> |
else { |
429 |
> |
t.quietlyJoin(); |
430 |
> |
if (ex == null && t.status < NORMAL) |
431 |
> |
ex = t.getException(); |
432 |
> |
} |
433 |
|
} |
434 |
|
} |
435 |
|
if (ex != null) |
439 |
|
/** |
440 |
|
* Forks all tasks in the specified collection, returning when |
441 |
|
* {@code isDone} holds for each task or an (unchecked) exception |
442 |
< |
* is encountered. If any task encounters an exception, others |
443 |
< |
* may be, but are not guaranteed to be, cancelled. If more than |
444 |
< |
* one task encounters an exception, then this method throws any |
445 |
< |
* one of these exceptions. The individual status of each task |
446 |
< |
* may be checked using {@link #getException()} and related |
447 |
< |
* methods. The behavior of this operation is undefined if the |
448 |
< |
* specified collection is modified while the operation is in |
449 |
< |
* progress. |
442 |
> |
* is encountered, in which case the exception is rethrown. If |
443 |
> |
* more than one task encounters an exception, then this method |
444 |
> |
* throws any one of these exceptions. If any task encounters an |
445 |
> |
* exception, others may be cancelled. However, the execution |
446 |
> |
* status of individual tasks is not guaranteed upon exceptional |
447 |
> |
* return. The status of each task may be obtained using {@link |
448 |
> |
* #getException()} and related methods to check if they have been |
449 |
> |
* cancelled, completed normally or exceptionally, or left |
450 |
> |
* unprocessed. |
451 |
|
* |
452 |
|
* <p>This method may be invoked only from within {@code |
453 |
|
* ForkJoinTask} computations (as may be determined using method |
477 |
|
} |
478 |
|
else if (i != 0) |
479 |
|
t.fork(); |
480 |
< |
else if (t.waitingInvoke() < NORMAL && ex == null) |
481 |
< |
ex = t.getException(); |
480 |
> |
else { |
481 |
> |
t.quietlyInvoke(); |
482 |
> |
if (ex == null && t.status < NORMAL) |
483 |
> |
ex = t.getException(); |
484 |
> |
} |
485 |
|
} |
486 |
|
for (int i = 1; i <= last; ++i) { |
487 |
|
ForkJoinTask<?> t = ts.get(i); |
488 |
|
if (t != null) { |
489 |
|
if (ex != null) |
490 |
|
t.cancel(false); |
491 |
< |
else if (t.waitingJoin() < NORMAL && ex == null) |
492 |
< |
ex = t.getException(); |
491 |
> |
else { |
492 |
> |
t.quietlyJoin(); |
493 |
> |
if (ex == null && t.status < NORMAL) |
494 |
> |
ex = t.getException(); |
495 |
> |
} |
496 |
|
} |
497 |
|
} |
498 |
|
if (ex != null) |
526 |
|
*/ |
527 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
528 |
|
setCompletion(CANCELLED); |
529 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
529 |
> |
return status == CANCELLED; |
530 |
|
} |
531 |
|
|
532 |
|
/** |
533 |
< |
* Cancels, ignoring any exceptions it throws. Used during worker |
534 |
< |
* and pool shutdown. |
533 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
534 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
535 |
> |
* exceptions, but if it does anyway, we have no recourse during |
536 |
> |
* shutdown, so guard against this case. |
537 |
|
*/ |
538 |
|
final void cancelIgnoringExceptions() { |
539 |
|
try { |
543 |
|
} |
544 |
|
|
545 |
|
/** |
546 |
< |
* Cancels ignoring exceptions if worker is terminating |
546 |
> |
* Cancels if current thread is a terminating worker thread, |
547 |
> |
* ignoring any exceptions thrown by cancel. |
548 |
|
*/ |
549 |
< |
private void cancelIfTerminating() { |
549 |
> |
final void cancelIfTerminating() { |
550 |
|
Thread t = Thread.currentThread(); |
551 |
|
if ((t instanceof ForkJoinWorkerThread) && |
552 |
|
((ForkJoinWorkerThread) t).isTerminating()) { |
562 |
|
} |
563 |
|
|
564 |
|
public final boolean isCancelled() { |
565 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
565 |
> |
return status == CANCELLED; |
566 |
|
} |
567 |
|
|
568 |
|
/** |
571 |
|
* @return {@code true} if this task threw an exception or was cancelled |
572 |
|
*/ |
573 |
|
public final boolean isCompletedAbnormally() { |
574 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
574 |
> |
return status < NORMAL; |
575 |
|
} |
576 |
|
|
577 |
|
/** |
582 |
|
* exception and was not cancelled |
583 |
|
*/ |
584 |
|
public final boolean isCompletedNormally() { |
585 |
< |
return (status & COMPLETION_MASK) == NORMAL; |
585 |
> |
return status == NORMAL; |
586 |
|
} |
587 |
|
|
588 |
|
/** |
593 |
|
* @return the exception, or {@code null} if none |
594 |
|
*/ |
595 |
|
public final Throwable getException() { |
596 |
< |
int s = status & COMPLETION_MASK; |
596 |
> |
int s = status; |
597 |
|
return ((s >= NORMAL) ? null : |
598 |
|
(s == CANCELLED) ? new CancellationException() : |
599 |
|
exceptionMap.get(this)); |
621 |
|
|
622 |
|
/** |
623 |
|
* Completes this task, and if not already aborted or cancelled, |
624 |
< |
* returning a {@code null} result upon {@code join} and related |
625 |
< |
* operations. This method may be used to provide results for |
626 |
< |
* asynchronous tasks, or to provide alternative handling for |
627 |
< |
* tasks that would not otherwise complete normally. Its use in |
628 |
< |
* other situations is discouraged. This method is |
629 |
< |
* overridable, but overridden versions must invoke {@code super} |
630 |
< |
* implementation to maintain guarantees. |
624 |
> |
* returning the given value as the result of subsequent |
625 |
> |
* invocations of {@code join} and related operations. This method |
626 |
> |
* may be used to provide results for asynchronous tasks, or to |
627 |
> |
* provide alternative handling for tasks that would not otherwise |
628 |
> |
* complete normally. Its use in other situations is |
629 |
> |
* discouraged. This method is overridable, but overridden |
630 |
> |
* versions must invoke {@code super} implementation to maintain |
631 |
> |
* guarantees. |
632 |
|
* |
633 |
|
* @param value the result value for this task |
634 |
|
*/ |
643 |
|
} |
644 |
|
|
645 |
|
public final V get() throws InterruptedException, ExecutionException { |
646 |
< |
int s = waitingJoin() & COMPLETION_MASK; |
646 |
> |
quietlyJoin(); |
647 |
|
if (Thread.interrupted()) |
648 |
|
throw new InterruptedException(); |
649 |
+ |
int s = status; |
650 |
|
if (s < NORMAL) { |
651 |
|
Throwable ex; |
652 |
|
if (s == CANCELLED) |
664 |
|
if (t instanceof ForkJoinWorkerThread) { |
665 |
|
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
666 |
|
if (status >= 0 && w.unpushTask(this)) |
667 |
< |
tryExec(); |
667 |
> |
quietlyExec(); |
668 |
|
pool = w.pool; |
669 |
|
} |
670 |
|
else |
671 |
|
pool = null; |
672 |
|
/* |
673 |
< |
* Timed wait loop intermixes cases for fj (pool != null) and |
673 |
> |
* Timed wait loop intermixes cases for FJ (pool != null) and |
674 |
|
* non FJ threads. For FJ, decrement pool count but don't try |
675 |
|
* for replacement; increment count on completion. For non-FJ, |
676 |
|
* deal with interrupts. This is messy, but a little less so |
678 |
|
*/ |
679 |
|
boolean interrupted = false; |
680 |
|
boolean dec = false; // true if pool count decremented |
681 |
+ |
long nanos = unit.toNanos(timeout); |
682 |
|
for (;;) { |
683 |
< |
if (Thread.interrupted() && pool == null) { |
683 |
> |
if (pool == null && Thread.interrupted()) { |
684 |
|
interrupted = true; |
685 |
|
break; |
686 |
|
} |
687 |
|
int s = status; |
688 |
|
if (s < 0) |
689 |
|
break; |
690 |
< |
if (UNSAFE.compareAndSwapInt(this, statusOffset, |
727 |
< |
s, s | SIGNAL)) { |
690 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) { |
691 |
|
long startTime = System.nanoTime(); |
729 |
– |
long nanos = unit.toNanos(timeout); |
692 |
|
long nt; // wait time |
693 |
|
while (status >= 0 && |
694 |
|
(nt = nanos - (System.nanoTime() - startTime)) > 0) { |
716 |
|
} |
717 |
|
} |
718 |
|
if (pool != null && dec) |
719 |
< |
pool.updateRunningCount(1); |
719 |
> |
pool.incrementRunningCount(); |
720 |
|
if (interrupted) |
721 |
|
throw new InterruptedException(); |
722 |
< |
int es = status & COMPLETION_MASK; |
722 |
> |
int es = status; |
723 |
|
if (es != NORMAL) { |
724 |
|
Throwable ex; |
725 |
|
if (es == CANCELLED) |
732 |
|
} |
733 |
|
|
734 |
|
/** |
735 |
< |
* Possibly executes other tasks until this task {@link #isDone is |
774 |
< |
* done}, then returns the result of the computation. This method |
775 |
< |
* may be more efficient than {@code join}, but is only applicable |
776 |
< |
* when there are no potential dependencies between continuation |
777 |
< |
* of the current task and that of any other task that might be |
778 |
< |
* executed while helping. (This usually holds for pure |
779 |
< |
* divide-and-conquer tasks). |
780 |
< |
* |
781 |
< |
* <p>This method may be invoked only from within {@code |
782 |
< |
* ForkJoinTask} computations (as may be determined using method |
783 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
784 |
< |
* result in exceptions or errors, possibly including {@code |
785 |
< |
* ClassCastException}. |
786 |
< |
* |
787 |
< |
* @return the computed result |
788 |
< |
*/ |
789 |
< |
public final V helpJoin() { |
790 |
< |
return reportResult(busyJoin()); |
791 |
< |
} |
792 |
< |
|
793 |
< |
/** |
794 |
< |
* Possibly executes other tasks until this task {@link #isDone is |
795 |
< |
* done}. This method may be useful when processing collections |
796 |
< |
* of tasks when some have been cancelled or otherwise known to |
797 |
< |
* have aborted. |
798 |
< |
* |
799 |
< |
* <p>This method may be invoked only from within {@code |
800 |
< |
* ForkJoinTask} computations (as may be determined using method |
801 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
802 |
< |
* result in exceptions or errors, possibly including {@code |
803 |
< |
* ClassCastException}. |
804 |
< |
*/ |
805 |
< |
public final void quietlyHelpJoin() { |
806 |
< |
busyJoin(); |
807 |
< |
} |
808 |
< |
|
809 |
< |
/** |
810 |
< |
* Joins this task, without returning its result or throwing an |
735 |
> |
* Joins this task, without returning its result or throwing its |
736 |
|
* exception. This method may be useful when processing |
737 |
|
* collections of tasks when some have been cancelled or otherwise |
738 |
|
* known to have aborted. |
739 |
|
*/ |
740 |
|
public final void quietlyJoin() { |
741 |
< |
waitingJoin(); |
741 |
> |
Thread t; |
742 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
743 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
744 |
> |
if (status >= 0) { |
745 |
> |
if (w.unpushTask(this)) { |
746 |
> |
boolean completed; |
747 |
> |
try { |
748 |
> |
completed = exec(); |
749 |
> |
} catch (Throwable rex) { |
750 |
> |
setExceptionalCompletion(rex); |
751 |
> |
return; |
752 |
> |
} |
753 |
> |
if (completed) { |
754 |
> |
setCompletion(NORMAL); |
755 |
> |
return; |
756 |
> |
} |
757 |
> |
} |
758 |
> |
w.joinTask(this); |
759 |
> |
} |
760 |
> |
} |
761 |
> |
else |
762 |
> |
externalAwaitDone(); |
763 |
|
} |
764 |
|
|
765 |
|
/** |
766 |
|
* Commences performing this task and awaits its completion if |
767 |
< |
* necessary, without returning its result or throwing an |
768 |
< |
* exception. This method may be useful when processing |
823 |
< |
* collections of tasks when some have been cancelled or otherwise |
824 |
< |
* known to have aborted. |
767 |
> |
* necessary, without returning its result or throwing its |
768 |
> |
* exception. |
769 |
|
*/ |
770 |
|
public final void quietlyInvoke() { |
771 |
< |
waitingInvoke(); |
771 |
> |
if (status >= 0) { |
772 |
> |
boolean completed; |
773 |
> |
try { |
774 |
> |
completed = exec(); |
775 |
> |
} catch (Throwable rex) { |
776 |
> |
setExceptionalCompletion(rex); |
777 |
> |
return; |
778 |
> |
} |
779 |
> |
if (completed) |
780 |
> |
setCompletion(NORMAL); |
781 |
> |
else |
782 |
> |
quietlyJoin(); |
783 |
> |
} |
784 |
|
} |
785 |
|
|
786 |
|
/** |
812 |
|
* pre-constructed trees of subtasks in loops. |
813 |
|
*/ |
814 |
|
public void reinitialize() { |
815 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
815 |
> |
if (status == EXCEPTIONAL) |
816 |
|
exceptionMap.remove(this); |
817 |
|
status = 0; |
818 |
|
} |
1102 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1103 |
|
|
1104 |
|
/** |
1105 |
< |
* Saves the state to a stream. |
1105 |
> |
* Saves the state to a stream (that is, serializes it). |
1106 |
|
* |
1107 |
|
* @serialData the current run status and the exception thrown |
1108 |
|
* during execution, or {@code null} if none |
1115 |
|
} |
1116 |
|
|
1117 |
|
/** |
1118 |
< |
* Reconstitutes the instance from a stream. |
1118 |
> |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1119 |
|
* |
1120 |
|
* @param s the stream |
1121 |
|
*/ |
1122 |
|
private void readObject(java.io.ObjectInputStream s) |
1123 |
|
throws java.io.IOException, ClassNotFoundException { |
1124 |
|
s.defaultReadObject(); |
1169 |
– |
status |= SIGNAL; // conservatively set external signal |
1125 |
|
Object ex = s.readObject(); |
1126 |
|
if (ex != null) |
1127 |
|
setExceptionalCompletion((Throwable) ex); |