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. |
59 |
> |
* additionally include {@link RejectedExecutionException} stemming |
60 |
> |
* from internal resource exhaustion, such as failure to allocate |
61 |
> |
* internal task queues. |
62 |
|
* |
63 |
|
* <p>The primary method for awaiting completion and extracting |
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 |
135 |
|
*/ |
136 |
|
public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
137 |
|
|
138 |
< |
/** |
139 |
< |
* Run control status bits packed into a single int to minimize |
140 |
< |
* footprint and to ensure atomicity (via CAS). Status is |
141 |
< |
* initially zero, and takes on nonnegative values until |
142 |
< |
* completed, upon which status holds COMPLETED. CANCELLED, or |
143 |
< |
* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
144 |
< |
* blocking waits by other threads have SIGNAL_MASK bits set -- |
145 |
< |
* bit 15 for external (nonFJ) waits, and the rest a count of |
146 |
< |
* waiting FJ threads. (This representation relies on |
147 |
< |
* ForkJoinPool max thread limits). Completion of a stolen task |
148 |
< |
* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even |
149 |
< |
* though suboptimal for some purposes, we use basic builtin |
150 |
< |
* wait/notify to take advantage of "monitor inflation" in JVMs |
151 |
< |
* that we would otherwise need to emulate to avoid adding further |
152 |
< |
* per-task bookkeeping overhead. Note that bits 16-28 are |
153 |
< |
* currently unused. Also value 0x80000000 is available as spare |
154 |
< |
* completion value. |
138 |
> |
/* |
139 |
> |
* See the internal documentation of class ForkJoinPool for a |
140 |
> |
* general implementation overview. ForkJoinTasks are mainly |
141 |
> |
* responsible for maintaining their "status" field amidst relays |
142 |
> |
* to methods in ForkJoinWorkerThread and ForkJoinPool. The |
143 |
> |
* methods of this class are more-or-less layered into (1) basic |
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. In particular, most |
148 |
> |
* join mechanics are in method quietlyJoin, below. |
149 |
> |
*/ |
150 |
> |
|
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. |
166 |
|
*/ |
167 |
+ |
|
168 |
+ |
/** The run status of this task */ |
169 |
|
volatile int status; // accessed directly by pool and workers |
170 |
|
|
171 |
< |
static final int COMPLETION_MASK = 0xe0000000; |
172 |
< |
static final int NORMAL = 0xe0000000; // == mask |
173 |
< |
static final int CANCELLED = 0xc0000000; |
174 |
< |
static final int EXCEPTIONAL = 0xa0000000; |
166 |
< |
static final int SIGNAL_MASK = 0x0000ffff; |
167 |
< |
static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
168 |
< |
static final int EXTERNAL_SIGNAL = 0x00008000; // top bit of low word |
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 |
185 |
|
Collections.synchronizedMap |
186 |
|
(new WeakHashMap<ForkJoinTask<?>, Throwable>()); |
187 |
|
|
188 |
< |
// within-package utilities |
188 |
> |
// Maintaining completion status |
189 |
|
|
190 |
|
/** |
191 |
< |
* Gets current worker thread, or null if not a worker thread. |
192 |
< |
*/ |
187 |
< |
static ForkJoinWorkerThread getWorker() { |
188 |
< |
Thread t = Thread.currentThread(); |
189 |
< |
return ((t instanceof ForkJoinWorkerThread) ? |
190 |
< |
(ForkJoinWorkerThread) t : null); |
191 |
< |
} |
192 |
< |
|
193 |
< |
final boolean casStatus(int cmp, int val) { |
194 |
< |
return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val); |
195 |
< |
} |
196 |
< |
|
197 |
< |
/** |
198 |
< |
* Workaround for not being able to rethrow unchecked exceptions. |
199 |
< |
*/ |
200 |
< |
static void rethrowException(Throwable ex) { |
201 |
< |
if (ex != null) |
202 |
< |
UNSAFE.throwException(ex); |
203 |
< |
} |
204 |
< |
|
205 |
< |
// Setting completion status |
206 |
< |
|
207 |
< |
/** |
208 |
< |
* Marks completion and wakes up threads waiting to join this task. |
191 |
> |
* Marks completion and wakes up threads waiting to join this task, |
192 |
> |
* also clearing signal request bits. |
193 |
|
* |
194 |
|
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
195 |
|
*/ |
196 |
< |
final void setCompletion(int completion) { |
197 |
< |
ForkJoinPool pool = getPool(); |
198 |
< |
if (pool != null) { |
199 |
< |
int s; // Clear signal bits while setting completion status |
200 |
< |
do {} while ((s = status) >= 0 && !casStatus(s, completion)); |
201 |
< |
|
202 |
< |
if ((s & SIGNAL_MASK) != 0) { |
219 |
< |
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
220 |
< |
pool.updateRunningCount(s); |
221 |
< |
synchronized (this) { notifyAll(); } |
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 != 0) |
201 |
> |
synchronized (this) { notifyAll(); } |
202 |
> |
break; |
203 |
|
} |
204 |
|
} |
224 |
– |
else |
225 |
– |
externallySetCompletion(completion); |
226 |
– |
} |
227 |
– |
|
228 |
– |
/** |
229 |
– |
* Version of setCompletion for non-FJ threads. Leaves signal |
230 |
– |
* bits for unblocked threads to adjust, and always notifies. |
231 |
– |
*/ |
232 |
– |
private void externallySetCompletion(int completion) { |
233 |
– |
int s; |
234 |
– |
do {} while ((s = status) >= 0 && |
235 |
– |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
236 |
– |
synchronized (this) { notifyAll(); } |
205 |
|
} |
206 |
|
|
207 |
|
/** |
208 |
< |
* Sets status to indicate normal completion. |
208 |
> |
* Records exception and sets exceptional completion. |
209 |
> |
* |
210 |
> |
* @return status on exit |
211 |
|
*/ |
212 |
< |
final void setNormalCompletion() { |
213 |
< |
// Try typical fast case -- single CAS, no signal, not already done. |
214 |
< |
// Manually expand casStatus to improve chances of inlining it |
245 |
< |
if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
246 |
< |
setCompletion(NORMAL); |
247 |
< |
} |
248 |
< |
|
249 |
< |
// internal waiting and notification |
250 |
< |
|
251 |
< |
/** |
252 |
< |
* Performs the actual monitor wait for awaitDone. |
253 |
< |
*/ |
254 |
< |
private void doAwaitDone() { |
255 |
< |
// Minimize lock bias and in/de-flation effects by maximizing |
256 |
< |
// chances of waiting inside sync |
257 |
< |
try { |
258 |
< |
while (status >= 0) |
259 |
< |
synchronized (this) { if (status >= 0) wait(); } |
260 |
< |
} catch (InterruptedException ie) { |
261 |
< |
onInterruptedWait(); |
262 |
< |
} |
212 |
> |
private void setExceptionalCompletion(Throwable rex) { |
213 |
> |
exceptionMap.put(this, rex); |
214 |
> |
setCompletion(EXCEPTIONAL); |
215 |
|
} |
216 |
|
|
217 |
|
/** |
218 |
< |
* Performs the actual timed monitor wait for awaitDone. |
218 |
> |
* Blocks a worker thread until completion. Called only by |
219 |
> |
* pool. Currently unused -- pool-based waits use timeout |
220 |
> |
* version below. |
221 |
|
*/ |
222 |
< |
private void doAwaitDone(long startTime, long nanos) { |
223 |
< |
synchronized (this) { |
222 |
> |
final void internalAwaitDone() { |
223 |
> |
int s; // the odd construction reduces lock bias effects |
224 |
> |
while ((s = status) >= 0) { |
225 |
|
try { |
226 |
< |
while (status >= 0) { |
227 |
< |
long nt = nanos - (System.nanoTime() - startTime); |
228 |
< |
if (nt <= 0) |
274 |
< |
break; |
275 |
< |
wait(nt / 1000000, (int) (nt % 1000000)); |
226 |
> |
synchronized(this) { |
227 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
228 |
> |
wait(); |
229 |
|
} |
230 |
|
} catch (InterruptedException ie) { |
231 |
< |
onInterruptedWait(); |
279 |
< |
} |
280 |
< |
} |
281 |
< |
} |
282 |
< |
|
283 |
< |
// Awaiting completion |
284 |
< |
|
285 |
< |
/** |
286 |
< |
* Sets status to indicate there is joiner, then waits for join, |
287 |
< |
* surrounded with pool notifications. |
288 |
< |
* |
289 |
< |
* @return status upon exit |
290 |
< |
*/ |
291 |
< |
private int awaitDone(ForkJoinWorkerThread w, |
292 |
< |
boolean maintainParallelism) { |
293 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
294 |
< |
int s; |
295 |
< |
while ((s = status) >= 0) { |
296 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
297 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
298 |
< |
doAwaitDone(); |
299 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
300 |
< |
adjustPoolCountsOnUnblock(pool); |
301 |
< |
break; |
231 |
> |
cancelIfTerminating(); |
232 |
|
} |
233 |
|
} |
304 |
– |
return s; |
234 |
|
} |
235 |
|
|
236 |
|
/** |
237 |
< |
* Timed version of awaitDone |
237 |
> |
* Blocks a worker thread until completed or timed out. Called |
238 |
> |
* only by pool. |
239 |
|
* |
240 |
< |
* @return status upon exit |
240 |
> |
* @return status on exit |
241 |
|
*/ |
242 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
313 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
242 |
> |
final int internalAwaitDone(long millis) { |
243 |
|
int s; |
244 |
< |
while ((s = status) >= 0) { |
245 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
246 |
< |
long startTime = System.nanoTime(); |
247 |
< |
if (pool == null || !pool.preJoin(this, false)) |
248 |
< |
doAwaitDone(startTime, nanos); |
320 |
< |
if ((s = status) >= 0) { |
321 |
< |
adjustPoolCountsOnCancelledWait(pool); |
322 |
< |
s = status; |
244 |
> |
if ((s = status) >= 0) { |
245 |
> |
try { |
246 |
> |
synchronized(this) { |
247 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
248 |
> |
wait(millis, 0); |
249 |
|
} |
250 |
< |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
251 |
< |
adjustPoolCountsOnUnblock(pool); |
326 |
< |
break; |
250 |
> |
} catch (InterruptedException ie) { |
251 |
> |
cancelIfTerminating(); |
252 |
|
} |
253 |
+ |
s = status; |
254 |
|
} |
255 |
|
return s; |
256 |
|
} |
257 |
|
|
258 |
|
/** |
259 |
< |
* Notifies pool that thread is unblocked. Called by signalled |
334 |
< |
* threads when woken by non-FJ threads (which is atypical). |
259 |
> |
* Blocks a non-worker-thread until completion. |
260 |
|
*/ |
261 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
261 |
> |
private void externalAwaitDone() { |
262 |
|
int s; |
263 |
< |
do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
264 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
265 |
< |
pool.updateRunningCount(s); |
266 |
< |
} |
267 |
< |
|
268 |
< |
/** |
269 |
< |
* Notifies pool to adjust counts on cancelled or timed out wait. |
270 |
< |
*/ |
271 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
272 |
< |
if (pool != null) { |
273 |
< |
int s; |
274 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
275 |
< |
if (casStatus(s, s - 1)) { |
351 |
< |
pool.updateRunningCount(1); |
263 |
> |
while ((s = status) >= 0) { |
264 |
> |
synchronized(this) { |
265 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){ |
266 |
> |
boolean interrupted = false; |
267 |
> |
while (status >= 0) { |
268 |
> |
try { |
269 |
> |
wait(); |
270 |
> |
} catch (InterruptedException ie) { |
271 |
> |
interrupted = true; |
272 |
> |
} |
273 |
> |
} |
274 |
> |
if (interrupted) |
275 |
> |
Thread.currentThread().interrupt(); |
276 |
|
break; |
277 |
|
} |
278 |
|
} |
280 |
|
} |
281 |
|
|
282 |
|
/** |
283 |
< |
* Handles interruptions during waits. |
284 |
< |
*/ |
285 |
< |
private void onInterruptedWait() { |
362 |
< |
ForkJoinWorkerThread w = getWorker(); |
363 |
< |
if (w == null) |
364 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
365 |
< |
else if (w.isTerminating()) |
366 |
< |
cancelIgnoringExceptions(); |
367 |
< |
// else if FJworker, ignore interrupt |
368 |
< |
} |
369 |
< |
|
370 |
< |
// Recording and reporting exceptions |
371 |
< |
|
372 |
< |
private void setDoneExceptionally(Throwable rex) { |
373 |
< |
exceptionMap.put(this, rex); |
374 |
< |
setCompletion(EXCEPTIONAL); |
375 |
< |
} |
376 |
< |
|
377 |
< |
/** |
378 |
< |
* Throws the exception associated with status s. |
379 |
< |
* |
380 |
< |
* @throws the exception |
381 |
< |
*/ |
382 |
< |
private void reportException(int s) { |
383 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
384 |
< |
if (s == CANCELLED) |
385 |
< |
throw new CancellationException(); |
386 |
< |
else |
387 |
< |
rethrowException(exceptionMap.get(this)); |
388 |
< |
} |
389 |
< |
} |
390 |
< |
|
391 |
< |
/** |
392 |
< |
* Returns result or throws exception using j.u.c.Future conventions. |
393 |
< |
* Only call when {@code isDone} known to be true or thread known |
394 |
< |
* to be interrupted. |
395 |
< |
*/ |
396 |
< |
private V reportFutureResult() |
397 |
< |
throws InterruptedException, ExecutionException { |
398 |
< |
if (Thread.interrupted()) |
399 |
< |
throw new InterruptedException(); |
400 |
< |
int s = status & COMPLETION_MASK; |
401 |
< |
if (s < NORMAL) { |
402 |
< |
Throwable ex; |
403 |
< |
if (s == CANCELLED) |
404 |
< |
throw new CancellationException(); |
405 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
406 |
< |
throw new ExecutionException(ex); |
407 |
< |
} |
408 |
< |
return getRawResult(); |
409 |
< |
} |
410 |
< |
|
411 |
< |
/** |
412 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
413 |
< |
* with timeouts. |
414 |
< |
*/ |
415 |
< |
private V reportTimedFutureResult() |
416 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
417 |
< |
if (Thread.interrupted()) |
418 |
< |
throw new InterruptedException(); |
419 |
< |
Throwable ex; |
420 |
< |
int s = status & COMPLETION_MASK; |
421 |
< |
if (s == NORMAL) |
422 |
< |
return getRawResult(); |
423 |
< |
else if (s == CANCELLED) |
424 |
< |
throw new CancellationException(); |
425 |
< |
else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
426 |
< |
throw new ExecutionException(ex); |
427 |
< |
else |
428 |
< |
throw new TimeoutException(); |
429 |
< |
} |
430 |
< |
|
431 |
< |
// internal execution methods |
432 |
< |
|
433 |
< |
/** |
434 |
< |
* Calls exec, recording completion, and rethrowing exception if |
435 |
< |
* encountered. Caller should normally check status before calling. |
436 |
< |
* |
437 |
< |
* @return true if completed normally |
438 |
< |
*/ |
439 |
< |
private boolean tryExec() { |
440 |
< |
try { // try block must contain only call to exec |
441 |
< |
if (!exec()) |
442 |
< |
return false; |
443 |
< |
} catch (Throwable rex) { |
444 |
< |
setDoneExceptionally(rex); |
445 |
< |
rethrowException(rex); |
446 |
< |
return false; // not reached |
447 |
< |
} |
448 |
< |
setNormalCompletion(); |
449 |
< |
return true; |
450 |
< |
} |
451 |
< |
|
452 |
< |
/** |
453 |
< |
* Main execution method used by worker threads. Invokes |
454 |
< |
* base computation unless already complete. |
283 |
> |
* Unless done, calls exec and records status if completed, but |
284 |
> |
* doesn't wait for completion otherwise. Primary execution method |
285 |
> |
* for ForkJoinWorkerThread. |
286 |
|
*/ |
287 |
|
final void quietlyExec() { |
457 |
– |
if (status >= 0) { |
458 |
– |
try { |
459 |
– |
if (!exec()) |
460 |
– |
return; |
461 |
– |
} catch (Throwable rex) { |
462 |
– |
setDoneExceptionally(rex); |
463 |
– |
return; |
464 |
– |
} |
465 |
– |
setNormalCompletion(); |
466 |
– |
} |
467 |
– |
} |
468 |
– |
|
469 |
– |
/** |
470 |
– |
* Calls exec(), recording but not rethrowing exception. |
471 |
– |
* Caller should normally check status before calling. |
472 |
– |
* |
473 |
– |
* @return true if completed normally |
474 |
– |
*/ |
475 |
– |
private boolean tryQuietlyInvoke() { |
288 |
|
try { |
289 |
< |
if (!exec()) |
290 |
< |
return false; |
289 |
> |
if (status < 0 || !exec()) |
290 |
> |
return; |
291 |
|
} catch (Throwable rex) { |
292 |
< |
setDoneExceptionally(rex); |
293 |
< |
return false; |
482 |
< |
} |
483 |
< |
setNormalCompletion(); |
484 |
< |
return true; |
485 |
< |
} |
486 |
< |
|
487 |
< |
/** |
488 |
< |
* Cancels, ignoring any exceptions it throws. |
489 |
< |
*/ |
490 |
< |
final void cancelIgnoringExceptions() { |
491 |
< |
try { |
492 |
< |
cancel(false); |
493 |
< |
} catch (Throwable ignore) { |
292 |
> |
setExceptionalCompletion(rex); |
293 |
> |
return; |
294 |
|
} |
295 |
< |
} |
496 |
< |
|
497 |
< |
/** |
498 |
< |
* Main implementation of helpJoin |
499 |
< |
*/ |
500 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
501 |
< |
int s; |
502 |
< |
ForkJoinTask<?> t; |
503 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
504 |
< |
t.quietlyExec(); |
505 |
< |
return (s >= 0) ? awaitDone(w, false) : s; // block if no work |
295 |
> |
setCompletion(NORMAL); // must be outside try block |
296 |
|
} |
297 |
|
|
298 |
|
// public methods |
330 |
|
* @return the computed result |
331 |
|
*/ |
332 |
|
public final V join() { |
333 |
< |
ForkJoinWorkerThread w = getWorker(); |
334 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
335 |
< |
reportException(awaitDone(w, true)); |
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 |
< |
if (status >= 0 && tryExec()) |
350 |
< |
return getRawResult(); |
351 |
< |
else |
352 |
< |
return join(); |
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 |
416 |
|
t.fork(); |
417 |
|
else { |
418 |
|
t.quietlyInvoke(); |
419 |
< |
if (ex == null) |
419 |
> |
if (ex == null && t.status < NORMAL) |
420 |
|
ex = t.getException(); |
421 |
|
} |
422 |
|
} |
427 |
|
t.cancel(false); |
428 |
|
else { |
429 |
|
t.quietlyJoin(); |
430 |
< |
if (ex == null) |
430 |
> |
if (ex == null && t.status < NORMAL) |
431 |
|
ex = t.getException(); |
432 |
|
} |
433 |
|
} |
434 |
|
} |
435 |
|
if (ex != null) |
436 |
< |
rethrowException(ex); |
436 |
> |
UNSAFE.throwException(ex); |
437 |
|
} |
438 |
|
|
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 |
479 |
|
t.fork(); |
480 |
|
else { |
481 |
|
t.quietlyInvoke(); |
482 |
< |
if (ex == null) |
482 |
> |
if (ex == null && t.status < NORMAL) |
483 |
|
ex = t.getException(); |
484 |
|
} |
485 |
|
} |
490 |
|
t.cancel(false); |
491 |
|
else { |
492 |
|
t.quietlyJoin(); |
493 |
< |
if (ex == null) |
493 |
> |
if (ex == null && t.status < NORMAL) |
494 |
|
ex = t.getException(); |
495 |
|
} |
496 |
|
} |
497 |
|
} |
498 |
|
if (ex != null) |
499 |
< |
rethrowException(ex); |
499 |
> |
UNSAFE.throwException(ex); |
500 |
|
return tasks; |
501 |
|
} |
502 |
|
|
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 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 { |
540 |
> |
cancel(false); |
541 |
> |
} catch (Throwable ignore) { |
542 |
> |
} |
543 |
> |
} |
544 |
> |
|
545 |
> |
/** |
546 |
> |
* Cancels if current thread is a terminating worker thread, |
547 |
> |
* ignoring any exceptions thrown by cancel. |
548 |
> |
*/ |
549 |
> |
final void cancelIfTerminating() { |
550 |
> |
Thread t = Thread.currentThread(); |
551 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
552 |
> |
((ForkJoinWorkerThread) t).isTerminating()) { |
553 |
> |
try { |
554 |
> |
cancel(false); |
555 |
> |
} catch (Throwable ignore) { |
556 |
> |
} |
557 |
> |
} |
558 |
|
} |
559 |
|
|
560 |
|
public final boolean isDone() { |
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)); |
609 |
|
* overridable, but overridden versions must invoke {@code super} |
610 |
|
* implementation to maintain guarantees. |
611 |
|
* |
612 |
< |
* @param ex the exception to throw. If this exception is |
613 |
< |
* not a RuntimeException or Error, the actual exception thrown |
614 |
< |
* will be a RuntimeException with cause ex. |
612 |
> |
* @param ex the exception to throw. If this exception is not a |
613 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
614 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
615 |
|
*/ |
616 |
|
public void completeExceptionally(Throwable ex) { |
617 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
618 |
< |
(ex instanceof Error) ? ex : |
619 |
< |
new RuntimeException(ex)); |
617 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
618 |
> |
(ex instanceof Error) ? ex : |
619 |
> |
new RuntimeException(ex)); |
620 |
|
} |
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 |
|
*/ |
636 |
|
try { |
637 |
|
setRawResult(value); |
638 |
|
} catch (Throwable rex) { |
639 |
< |
setDoneExceptionally(rex); |
639 |
> |
setExceptionalCompletion(rex); |
640 |
|
return; |
641 |
|
} |
642 |
< |
setNormalCompletion(); |
642 |
> |
setCompletion(NORMAL); |
643 |
|
} |
644 |
|
|
645 |
|
public final V get() throws InterruptedException, ExecutionException { |
646 |
< |
ForkJoinWorkerThread w = getWorker(); |
647 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
648 |
< |
awaitDone(w, true); |
649 |
< |
return reportFutureResult(); |
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) |
653 |
> |
throw new CancellationException(); |
654 |
> |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
655 |
> |
throw new ExecutionException(ex); |
656 |
> |
} |
657 |
> |
return getRawResult(); |
658 |
|
} |
659 |
|
|
660 |
|
public final V get(long timeout, TimeUnit unit) |
661 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
662 |
+ |
Thread t = Thread.currentThread(); |
663 |
+ |
ForkJoinPool pool; |
664 |
+ |
if (t instanceof ForkJoinWorkerThread) { |
665 |
+ |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
666 |
+ |
if (status >= 0 && w.unpushTask(this)) |
667 |
+ |
quietlyExec(); |
668 |
+ |
pool = w.pool; |
669 |
+ |
} |
670 |
+ |
else |
671 |
+ |
pool = null; |
672 |
+ |
/* |
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 |
677 |
+ |
* than is splitting the FJ and nonFJ cases. |
678 |
+ |
*/ |
679 |
+ |
boolean interrupted = false; |
680 |
+ |
boolean dec = false; // true if pool count decremented |
681 |
|
long nanos = unit.toNanos(timeout); |
682 |
< |
ForkJoinWorkerThread w = getWorker(); |
683 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
684 |
< |
awaitDone(w, nanos); |
685 |
< |
return reportTimedFutureResult(); |
686 |
< |
} |
687 |
< |
|
688 |
< |
/** |
689 |
< |
* Possibly executes other tasks until this task {@link #isDone is |
690 |
< |
* done}, then returns the result of the computation. This method |
691 |
< |
* may be more efficient than {@code join}, but is only applicable |
692 |
< |
* when there are no potential dependencies between continuation |
693 |
< |
* of the current task and that of any other task that might be |
694 |
< |
* executed while helping. (This usually holds for pure |
695 |
< |
* divide-and-conquer tasks). |
696 |
< |
* |
697 |
< |
* <p>This method may be invoked only from within {@code |
698 |
< |
* ForkJoinTask} computations (as may be determined using method |
699 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
700 |
< |
* result in exceptions or errors, possibly including {@code |
701 |
< |
* ClassCastException}. |
702 |
< |
* |
703 |
< |
* @return the computed result |
704 |
< |
*/ |
705 |
< |
public final V helpJoin() { |
706 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
707 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
708 |
< |
reportException(busyJoin(w)); |
709 |
< |
return getRawResult(); |
710 |
< |
} |
711 |
< |
|
712 |
< |
/** |
713 |
< |
* Possibly executes other tasks until this task {@link #isDone is |
714 |
< |
* done}. This method may be useful when processing collections |
715 |
< |
* of tasks when some have been cancelled or otherwise known to |
716 |
< |
* have aborted. |
861 |
< |
* |
862 |
< |
* <p>This method may be invoked only from within {@code |
863 |
< |
* ForkJoinTask} computations (as may be determined using method |
864 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
865 |
< |
* result in exceptions or errors, possibly including {@code |
866 |
< |
* ClassCastException}. |
867 |
< |
*/ |
868 |
< |
public final void quietlyHelpJoin() { |
869 |
< |
if (status >= 0) { |
870 |
< |
ForkJoinWorkerThread w = |
871 |
< |
(ForkJoinWorkerThread) Thread.currentThread(); |
872 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
873 |
< |
busyJoin(w); |
682 |
> |
for (;;) { |
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, s, SIGNAL)) { |
691 |
> |
long startTime = System.nanoTime(); |
692 |
> |
long nt; // wait time |
693 |
> |
while (status >= 0 && |
694 |
> |
(nt = nanos - (System.nanoTime() - startTime)) > 0) { |
695 |
> |
if (pool != null && !dec) |
696 |
> |
dec = pool.tryDecrementRunningCount(); |
697 |
> |
else { |
698 |
> |
long ms = nt / 1000000; |
699 |
> |
int ns = (int) (nt % 1000000); |
700 |
> |
try { |
701 |
> |
synchronized(this) { |
702 |
> |
if (status >= 0) |
703 |
> |
wait(ms, ns); |
704 |
> |
} |
705 |
> |
} catch (InterruptedException ie) { |
706 |
> |
if (pool != null) |
707 |
> |
cancelIfTerminating(); |
708 |
> |
else { |
709 |
> |
interrupted = true; |
710 |
> |
break; |
711 |
> |
} |
712 |
> |
} |
713 |
> |
} |
714 |
> |
} |
715 |
> |
break; |
716 |
> |
} |
717 |
|
} |
718 |
+ |
if (pool != null && dec) |
719 |
+ |
pool.incrementRunningCount(); |
720 |
+ |
if (interrupted) |
721 |
+ |
throw new InterruptedException(); |
722 |
+ |
int es = status; |
723 |
+ |
if (es != NORMAL) { |
724 |
+ |
Throwable ex; |
725 |
+ |
if (es == CANCELLED) |
726 |
+ |
throw new CancellationException(); |
727 |
+ |
if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
728 |
+ |
throw new ExecutionException(ex); |
729 |
+ |
throw new TimeoutException(); |
730 |
+ |
} |
731 |
+ |
return getRawResult(); |
732 |
|
} |
733 |
|
|
734 |
|
/** |
735 |
< |
* 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 |
< |
if (status >= 0) { |
742 |
< |
ForkJoinWorkerThread w = getWorker(); |
743 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
744 |
< |
awaitDone(w, true); |
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 |
895 |
< |
* collections of tasks when some have been cancelled or otherwise |
896 |
< |
* known to have aborted. |
767 |
> |
* necessary, without returning its result or throwing its |
768 |
> |
* exception. |
769 |
|
*/ |
770 |
|
public final void quietlyInvoke() { |
771 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
772 |
< |
quietlyJoin(); |
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 |
< |
* Save 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 |
< |
* Reconstitute 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(); |
1242 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1243 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1125 |
|
Object ex = s.readObject(); |
1126 |
|
if (ex != null) |
1127 |
< |
setDoneExceptionally((Throwable) ex); |
1127 |
> |
setExceptionalCompletion((Throwable) ex); |
1128 |
|
} |
1129 |
|
|
1130 |
|
// Unsafe mechanics |