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package jsr166y; |
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import java.util.concurrent.*; |
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import java.io.Serializable; |
11 |
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import java.util.Collection; |
12 |
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import java.util.Collections; |
27 |
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* start other subtasks. As indicated by the name of this class, |
28 |
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* many programs using {@code ForkJoinTask} employ only methods |
29 |
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* {@link #fork} and {@link #join}, or derivatives such as {@link |
30 |
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* #invokeAll}. However, this class also provides a number of other |
31 |
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* methods that can come into play in advanced usages, as well as |
32 |
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* extension mechanics that allow support of new forms of fork/join |
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* processing. |
30 |
> |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
31 |
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* provides a number of other methods that can come into play in |
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* advanced usages, as well as extension mechanics that allow |
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* support of new forms of fork/join processing. |
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* |
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* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
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* The efficiency of {@code ForkJoinTask}s stems from a set of |
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* results of a task is {@link #join}, but there are several variants: |
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* The {@link Future#get} methods support interruptible and/or timed |
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* waits for completion and report results using {@code Future} |
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* conventions. Method {@link #helpJoin} enables callers to actively |
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* execute other tasks while awaiting joins, which is sometimes more |
69 |
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* efficient but only applies when all subtasks are known to be |
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* strictly tree-structured. Method {@link #invoke} is semantically |
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* conventions. Method {@link #invoke} is semantically |
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* equivalent to {@code fork(); join()} but always attempts to begin |
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* execution in the current thread. The "<em>quiet</em>" forms of |
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* these methods do not extract results or report exceptions. These |
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* ForkJoinTasks (as may be determined using method {@link |
100 |
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* #inForkJoinPool}). Attempts to invoke them in other contexts |
101 |
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* result in exceptions or errors, possibly including |
102 |
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* ClassCastException. |
102 |
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* {@code ClassCastException}. |
103 |
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* |
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* <p>Most base support methods are {@code final}, to prevent |
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* overriding of implementations that are intrinsically tied to the |
121 |
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* |
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* <p>This class provides {@code adapt} methods for {@link Runnable} |
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* and {@link Callable}, that may be of use when mixing execution of |
124 |
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* {@code ForkJoinTasks} with other kinds of tasks. When all tasks |
125 |
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* are of this form, consider using a pool in |
130 |
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* {@linkplain ForkJoinPool#setAsyncMode async mode}. |
124 |
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* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
125 |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
126 |
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* |
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* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
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* used in extensions such as remote execution frameworks. It is |
143 |
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* status maintenance (2) execution and awaiting completion (3) |
144 |
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* user-level methods that additionally report results. This is |
145 |
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* sometimes hard to see because this file orders exported methods |
146 |
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* in a way that flows well in javadocs. |
146 |
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* in a way that flows well in javadocs. In particular, most |
147 |
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* join mechanics are in method quietlyJoin, below. |
148 |
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*/ |
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|
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/** |
151 |
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* Run control status bits packed into a single int to minimize |
152 |
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* footprint and to ensure atomicity (via CAS). Status is |
153 |
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* initially zero, and takes on nonnegative values until |
154 |
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* completed, upon which status holds COMPLETED. CANCELLED, or |
155 |
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* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
156 |
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* blocking waits by other threads have SIGNAL_MASK bits set -- |
157 |
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* bit 15 for external (nonFJ) waits, and the rest a count of |
158 |
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* waiting FJ threads. (This representation relies on |
159 |
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* ForkJoinPool max thread limits). Signal counts are not directly |
160 |
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* incremented by ForkJoinTask methods, but instead via a call to |
161 |
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* requestSignal within ForkJoinPool.preJoin, once their need is |
162 |
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* established. |
163 |
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* |
164 |
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* Completion of a stolen task with SIGNAL_MASK bits set awakens |
169 |
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* any waiters via notifyAll. Even though suboptimal for some |
170 |
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* purposes, we use basic builtin wait/notify to take advantage of |
171 |
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* "monitor inflation" in JVMs that we would otherwise need to |
172 |
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* emulate to avoid adding further per-task bookkeeping overhead. |
173 |
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* We want these monitors to be "fat", i.e., not use biasing or |
174 |
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* thin-lock techniques, so use some odd coding idioms that tend |
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* to avoid them. |
176 |
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* |
177 |
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* Note that bits 16-28 are currently unused. Also value |
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* 0x80000000 is available as spare completion value. |
150 |
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/* |
151 |
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* The status field holds run control status bits packed into a |
152 |
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* single int to minimize footprint and to ensure atomicity (via |
153 |
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* CAS). Status is initially zero, and takes on nonnegative |
154 |
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* values until completed, upon which status holds value |
155 |
> |
* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
156 |
> |
* waits by other threads have the SIGNAL bit set. Completion of |
157 |
> |
* a stolen task with SIGNAL set awakens any waiters via |
158 |
> |
* notifyAll. Even though suboptimal for some purposes, we use |
159 |
> |
* basic builtin wait/notify to take advantage of "monitor |
160 |
> |
* inflation" in JVMs that we would otherwise need to emulate to |
161 |
> |
* avoid adding further per-task bookkeeping overhead. We want |
162 |
> |
* these monitors to be "fat", i.e., not use biasing or thin-lock |
163 |
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* techniques, so use some odd coding idioms that tend to avoid |
164 |
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* them. |
165 |
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*/ |
166 |
+ |
|
167 |
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/** The run status of this task */ |
168 |
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volatile int status; // accessed directly by pool and workers |
169 |
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|
170 |
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private static final int COMPLETION_MASK = 0xe0000000; |
171 |
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private static final int NORMAL = 0xe0000000; // == mask |
172 |
< |
private static final int CANCELLED = 0xc0000000; |
173 |
< |
private static final int EXCEPTIONAL = 0xa0000000; |
186 |
< |
private static final int SIGNAL_MASK = 0x0000ffff; |
187 |
< |
private static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
188 |
< |
private static final int EXTERNAL_SIGNAL = 0x00008000; |
170 |
> |
private static final int NORMAL = -1; |
171 |
> |
private static final int CANCELLED = -2; |
172 |
> |
private static final int EXCEPTIONAL = -3; |
173 |
> |
private static final int SIGNAL = 1; |
174 |
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|
175 |
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/** |
176 |
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* Table of exceptions thrown by tasks, to enable reporting by |
196 |
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int s; |
197 |
|
while ((s = status) >= 0) { |
198 |
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if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) { |
199 |
< |
if ((s & SIGNAL_MASK) != 0) { |
215 |
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Thread t = Thread.currentThread(); |
216 |
< |
if (t instanceof ForkJoinWorkerThread) |
217 |
< |
((ForkJoinWorkerThread) t).pool.updateRunningCount |
218 |
< |
(s & INTERNAL_SIGNAL_MASK); |
199 |
> |
if (s != 0) |
200 |
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synchronized (this) { notifyAll(); } |
201 |
< |
} |
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return; |
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> |
break; |
202 |
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} |
203 |
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} |
204 |
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} |
205 |
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|
206 |
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/** |
207 |
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* Record exception and set exceptional completion |
207 |
> |
* Records exception and sets exceptional completion. |
208 |
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* |
209 |
> |
* @return status on exit |
210 |
|
*/ |
211 |
< |
private void setDoneExceptionally(Throwable rex) { |
211 |
> |
private void setExceptionalCompletion(Throwable rex) { |
212 |
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exceptionMap.put(this, rex); |
213 |
|
setCompletion(EXCEPTIONAL); |
214 |
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} |
215 |
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|
216 |
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/** |
217 |
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* Main internal execution method: Unless done, calls exec and |
218 |
< |
* records completion. |
219 |
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* |
238 |
< |
* @return true if ran and completed normally |
217 |
> |
* Blocks a worker thread until completion. Called only by |
218 |
> |
* pool. Currently unused -- pool-based waits use timeout |
219 |
> |
* version below. |
220 |
|
*/ |
221 |
< |
final boolean tryExec() { |
222 |
< |
try { |
223 |
< |
if (status < 0 || !exec()) |
224 |
< |
return false; |
225 |
< |
} catch (Throwable rex) { |
226 |
< |
setDoneExceptionally(rex); |
227 |
< |
return false; |
221 |
> |
final void internalAwaitDone() { |
222 |
> |
int s; // the odd construction reduces lock bias effects |
223 |
> |
while ((s = status) >= 0) { |
224 |
> |
try { |
225 |
> |
synchronized (this) { |
226 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
227 |
> |
wait(); |
228 |
> |
} |
229 |
> |
} catch (InterruptedException ie) { |
230 |
> |
cancelIfTerminating(); |
231 |
> |
} |
232 |
|
} |
248 |
– |
setCompletion(NORMAL); // must be outside try block |
249 |
– |
return true; |
233 |
|
} |
234 |
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|
235 |
|
/** |
236 |
< |
* Increments internal signal count (thus requesting signal upon |
237 |
< |
* completion) unless already done. Call only once per join. |
255 |
< |
* Used by ForkJoinPool.preJoin. |
236 |
> |
* Blocks a worker thread until completed or timed out. Called |
237 |
> |
* only by pool. |
238 |
|
* |
239 |
< |
* @return status |
239 |
> |
* @return status on exit |
240 |
|
*/ |
241 |
< |
final int requestSignal() { |
241 |
> |
final int internalAwaitDone(long millis) { |
242 |
|
int s; |
243 |
< |
do {} while ((s = status) >= 0 && |
244 |
< |
!UNSAFE.compareAndSwapInt(this, statusOffset, s, s + 1)); |
245 |
< |
return s; |
246 |
< |
} |
247 |
< |
|
266 |
< |
/** |
267 |
< |
* Sets external signal request unless already done. |
268 |
< |
* |
269 |
< |
* @return status |
270 |
< |
*/ |
271 |
< |
private int requestExternalSignal() { |
272 |
< |
int s; |
273 |
< |
do {} while ((s = status) >= 0 && |
274 |
< |
!UNSAFE.compareAndSwapInt(this, statusOffset, |
275 |
< |
s, s | EXTERNAL_SIGNAL)); |
276 |
< |
return s; |
277 |
< |
} |
278 |
< |
|
279 |
< |
/* |
280 |
< |
* Awaiting completion. The four versions, internal vs external X |
281 |
< |
* untimed vs timed, have the same overall structure but differ |
282 |
< |
* from each other enough to defy simple integration. |
283 |
< |
*/ |
284 |
< |
|
285 |
< |
/** |
286 |
< |
* Blocks a worker until this task is done, also maintaining pool |
287 |
< |
* and signal counts |
288 |
< |
*/ |
289 |
< |
private void awaitDone(ForkJoinWorkerThread w) { |
290 |
< |
if (status >= 0) { |
291 |
< |
w.pool.preJoin(this); |
292 |
< |
while (status >= 0) { |
293 |
< |
try { // minimize lock scope |
294 |
< |
synchronized(this) { |
295 |
< |
if (status >= 0) |
296 |
< |
wait(); |
297 |
< |
else { // help release; also helps avoid lock-biasing |
298 |
< |
notifyAll(); |
299 |
< |
break; |
300 |
< |
} |
301 |
< |
} |
302 |
< |
} catch (InterruptedException ie) { |
303 |
< |
cancelIfTerminating(); |
243 |
> |
if ((s = status) >= 0) { |
244 |
> |
try { |
245 |
> |
synchronized (this) { |
246 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
247 |
> |
wait(millis, 0); |
248 |
|
} |
249 |
+ |
} catch (InterruptedException ie) { |
250 |
+ |
cancelIfTerminating(); |
251 |
|
} |
252 |
+ |
s = status; |
253 |
|
} |
254 |
+ |
return s; |
255 |
|
} |
256 |
|
|
257 |
|
/** |
258 |
< |
* Blocks a non-ForkJoin thread until this task is done. |
258 |
> |
* Blocks a non-worker-thread until completion. |
259 |
|
*/ |
260 |
|
private void externalAwaitDone() { |
261 |
< |
if (requestExternalSignal() >= 0) { |
262 |
< |
boolean interrupted = false; |
263 |
< |
while (status >= 0) { |
264 |
< |
try { |
265 |
< |
synchronized(this) { |
266 |
< |
if (status >= 0) |
261 |
> |
int s; |
262 |
> |
while ((s = status) >= 0) { |
263 |
> |
synchronized (this) { |
264 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) { |
265 |
> |
boolean interrupted = false; |
266 |
> |
while (status >= 0) { |
267 |
> |
try { |
268 |
|
wait(); |
269 |
< |
else { |
270 |
< |
notifyAll(); |
322 |
< |
break; |
323 |
< |
} |
324 |
< |
} |
325 |
< |
} catch (InterruptedException ie) { |
326 |
< |
interrupted = true; |
327 |
< |
} |
328 |
< |
} |
329 |
< |
if (interrupted) |
330 |
< |
Thread.currentThread().interrupt(); |
331 |
< |
} |
332 |
< |
} |
333 |
< |
|
334 |
< |
/** |
335 |
< |
* Blocks a worker until this task is done or timeout elapses |
336 |
< |
*/ |
337 |
< |
private void timedAwaitDone(ForkJoinWorkerThread w, long nanos) { |
338 |
< |
if (status >= 0) { |
339 |
< |
long startTime = System.nanoTime(); |
340 |
< |
ForkJoinPool pool = w.pool; |
341 |
< |
pool.preJoin(this); |
342 |
< |
while (status >= 0) { |
343 |
< |
long nt = nanos - (System.nanoTime() - startTime); |
344 |
< |
if (nt > 0) { |
345 |
< |
long ms = nt / 1000000; |
346 |
< |
int ns = (int) (nt % 1000000); |
347 |
< |
try { |
348 |
< |
synchronized(this) { if (status >= 0) wait(ms, ns); } |
349 |
< |
} catch (InterruptedException ie) { |
350 |
< |
cancelIfTerminating(); |
351 |
< |
} |
352 |
< |
} |
353 |
< |
else { |
354 |
< |
int s; // adjust running count on timeout |
355 |
< |
while ((s = status) >= 0 && |
356 |
< |
(s & INTERNAL_SIGNAL_MASK) != 0) { |
357 |
< |
if (UNSAFE.compareAndSwapInt(this, statusOffset, |
358 |
< |
s, s - 1)) { |
359 |
< |
pool.updateRunningCount(1); |
360 |
< |
break; |
269 |
> |
} catch (InterruptedException ie) { |
270 |
> |
interrupted = true; |
271 |
|
} |
272 |
|
} |
273 |
+ |
if (interrupted) |
274 |
+ |
Thread.currentThread().interrupt(); |
275 |
|
break; |
276 |
|
} |
277 |
|
} |
279 |
|
} |
280 |
|
|
281 |
|
/** |
282 |
< |
* Blocks a non-ForkJoin thread until this task is done or timeout elapses |
282 |
> |
* Unless done, calls exec and records status if completed, but |
283 |
> |
* doesn't wait for completion otherwise. Primary execution method |
284 |
> |
* for ForkJoinWorkerThread. |
285 |
|
*/ |
286 |
< |
private void externalTimedAwaitDone(long nanos) { |
287 |
< |
if (requestExternalSignal() >= 0) { |
288 |
< |
long startTime = System.nanoTime(); |
289 |
< |
boolean interrupted = false; |
290 |
< |
while (status >= 0) { |
291 |
< |
long nt = nanos - (System.nanoTime() - startTime); |
292 |
< |
if (nt <= 0) |
379 |
< |
break; |
380 |
< |
long ms = nt / 1000000; |
381 |
< |
int ns = (int) (nt % 1000000); |
382 |
< |
try { |
383 |
< |
synchronized(this) { if (status >= 0) wait(ms, ns); } |
384 |
< |
} catch (InterruptedException ie) { |
385 |
< |
interrupted = true; |
386 |
< |
} |
387 |
< |
} |
388 |
< |
if (interrupted) |
389 |
< |
Thread.currentThread().interrupt(); |
390 |
< |
} |
391 |
< |
} |
392 |
< |
|
393 |
< |
// reporting results |
394 |
< |
|
395 |
< |
/** |
396 |
< |
* Returns result or throws the exception associated with status. |
397 |
< |
* Uses Unsafe as a workaround for javac not allowing rethrow of |
398 |
< |
* unchecked exceptions. |
399 |
< |
*/ |
400 |
< |
private V reportResult() { |
401 |
< |
if ((status & COMPLETION_MASK) < NORMAL) { |
402 |
< |
Throwable ex = getException(); |
403 |
< |
if (ex != null) |
404 |
< |
UNSAFE.throwException(ex); |
405 |
< |
} |
406 |
< |
return getRawResult(); |
407 |
< |
} |
408 |
< |
|
409 |
< |
/** |
410 |
< |
* Returns result or throws exception using j.u.c.Future conventions. |
411 |
< |
* Only call when {@code isDone} known to be true or thread known |
412 |
< |
* to be interrupted. |
413 |
< |
*/ |
414 |
< |
private V reportFutureResult() |
415 |
< |
throws InterruptedException, ExecutionException { |
416 |
< |
if (Thread.interrupted()) |
417 |
< |
throw new InterruptedException(); |
418 |
< |
int s = status & COMPLETION_MASK; |
419 |
< |
if (s < NORMAL) { |
420 |
< |
Throwable ex; |
421 |
< |
if (s == CANCELLED) |
422 |
< |
throw new CancellationException(); |
423 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
424 |
< |
throw new ExecutionException(ex); |
286 |
> |
final void quietlyExec() { |
287 |
> |
try { |
288 |
> |
if (status < 0 || !exec()) |
289 |
> |
return; |
290 |
> |
} catch (Throwable rex) { |
291 |
> |
setExceptionalCompletion(rex); |
292 |
> |
return; |
293 |
|
} |
294 |
< |
return getRawResult(); |
427 |
< |
} |
428 |
< |
|
429 |
< |
/** |
430 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
431 |
< |
* with timeouts. |
432 |
< |
*/ |
433 |
< |
private V reportTimedFutureResult() |
434 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
435 |
< |
if (Thread.interrupted()) |
436 |
< |
throw new InterruptedException(); |
437 |
< |
Throwable ex; |
438 |
< |
int s = status & COMPLETION_MASK; |
439 |
< |
if (s == NORMAL) |
440 |
< |
return getRawResult(); |
441 |
< |
else if (s == CANCELLED) |
442 |
< |
throw new CancellationException(); |
443 |
< |
else if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
444 |
< |
throw new ExecutionException(ex); |
445 |
< |
else |
446 |
< |
throw new TimeoutException(); |
294 |
> |
setCompletion(NORMAL); // must be outside try block |
295 |
|
} |
296 |
|
|
297 |
|
// public methods |
330 |
|
*/ |
331 |
|
public final V join() { |
332 |
|
quietlyJoin(); |
333 |
< |
return reportResult(); |
333 |
> |
Throwable ex; |
334 |
> |
if (status < NORMAL && (ex = getException()) != null) |
335 |
> |
UNSAFE.throwException(ex); |
336 |
> |
return getRawResult(); |
337 |
|
} |
338 |
|
|
339 |
|
/** |
340 |
|
* Commences performing this task, awaits its completion if |
341 |
< |
* necessary, and return its result, or throws an (unchecked) |
342 |
< |
* exception if the underlying computation did so. |
341 |
> |
* necessary, and returns its result, or throws an (unchecked) |
342 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
343 |
> |
* computation did so. |
344 |
|
* |
345 |
|
* @return the computed result |
346 |
|
*/ |
347 |
|
public final V invoke() { |
348 |
< |
if (!tryExec()) |
349 |
< |
quietlyJoin(); |
350 |
< |
return reportResult(); |
348 |
> |
quietlyInvoke(); |
349 |
> |
Throwable ex; |
350 |
> |
if (status < NORMAL && (ex = getException()) != null) |
351 |
> |
UNSAFE.throwException(ex); |
352 |
> |
return getRawResult(); |
353 |
|
} |
354 |
|
|
355 |
|
/** |
356 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
357 |
|
* each task or an (unchecked) exception is encountered, in which |
358 |
< |
* case the exception is rethrown. If either task encounters an |
359 |
< |
* exception, the other one may be, but is not guaranteed to be, |
360 |
< |
* cancelled. If both tasks throw an exception, then this method |
361 |
< |
* throws one of them. The individual status of each task may be |
362 |
< |
* checked using {@link #getException()} and related methods. |
358 |
> |
* case the exception is rethrown. If more than one task |
359 |
> |
* encounters an exception, then this method throws any one of |
360 |
> |
* these exceptions. If any task encounters an exception, the |
361 |
> |
* other may be cancelled. However, the execution status of |
362 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
363 |
> |
* status of each task may be obtained using {@link |
364 |
> |
* #getException()} and related methods to check if they have been |
365 |
> |
* cancelled, completed normally or exceptionally, or left |
366 |
> |
* unprocessed. |
367 |
|
* |
368 |
|
* <p>This method may be invoked only from within {@code |
369 |
|
* ForkJoinTask} computations (as may be determined using method |
384 |
|
/** |
385 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
386 |
|
* each task or an (unchecked) exception is encountered, in which |
387 |
< |
* case the exception is rethrown. If any task encounters an |
388 |
< |
* exception, others may be, but are not guaranteed to be, |
389 |
< |
* cancelled. If more than one task encounters an exception, then |
390 |
< |
* this method throws any one of these exceptions. The individual |
391 |
< |
* status of each task may be checked using {@link #getException()} |
392 |
< |
* and related methods. |
387 |
> |
* case the exception is rethrown. If more than one task |
388 |
> |
* encounters an exception, then this method throws any one of |
389 |
> |
* these exceptions. If any task encounters an exception, others |
390 |
> |
* may be cancelled. However, the execution status of individual |
391 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
392 |
> |
* each task may be obtained using {@link #getException()} and |
393 |
> |
* related methods to check if they have been cancelled, completed |
394 |
> |
* normally or exceptionally, or left unprocessed. |
395 |
|
* |
396 |
|
* <p>This method may be invoked only from within {@code |
397 |
|
* ForkJoinTask} computations (as may be determined using method |
415 |
|
t.fork(); |
416 |
|
else { |
417 |
|
t.quietlyInvoke(); |
418 |
< |
if (ex == null) |
418 |
> |
if (ex == null && t.status < NORMAL) |
419 |
|
ex = t.getException(); |
420 |
|
} |
421 |
|
} |
426 |
|
t.cancel(false); |
427 |
|
else { |
428 |
|
t.quietlyJoin(); |
429 |
< |
if (ex == null) |
429 |
> |
if (ex == null && t.status < NORMAL) |
430 |
|
ex = t.getException(); |
431 |
|
} |
432 |
|
} |
438 |
|
/** |
439 |
|
* Forks all tasks in the specified collection, returning when |
440 |
|
* {@code isDone} holds for each task or an (unchecked) exception |
441 |
< |
* is encountered. If any task encounters an exception, others |
442 |
< |
* may be, but are not guaranteed to be, cancelled. If more than |
443 |
< |
* one task encounters an exception, then this method throws any |
444 |
< |
* one of these exceptions. The individual status of each task |
445 |
< |
* may be checked using {@link #getException()} and related |
446 |
< |
* methods. The behavior of this operation is undefined if the |
447 |
< |
* specified collection is modified while the operation is in |
448 |
< |
* progress. |
441 |
> |
* is encountered, in which case the exception is rethrown. If |
442 |
> |
* more than one task encounters an exception, then this method |
443 |
> |
* throws any one of these exceptions. If any task encounters an |
444 |
> |
* exception, others may be cancelled. However, the execution |
445 |
> |
* status of individual tasks is not guaranteed upon exceptional |
446 |
> |
* return. The status of each task may be obtained using {@link |
447 |
> |
* #getException()} and related methods to check if they have been |
448 |
> |
* cancelled, completed normally or exceptionally, or left |
449 |
> |
* unprocessed. |
450 |
|
* |
451 |
|
* <p>This method may be invoked only from within {@code |
452 |
|
* ForkJoinTask} computations (as may be determined using method |
478 |
|
t.fork(); |
479 |
|
else { |
480 |
|
t.quietlyInvoke(); |
481 |
< |
if (ex == null) |
481 |
> |
if (ex == null && t.status < NORMAL) |
482 |
|
ex = t.getException(); |
483 |
|
} |
484 |
|
} |
489 |
|
t.cancel(false); |
490 |
|
else { |
491 |
|
t.quietlyJoin(); |
492 |
< |
if (ex == null) |
492 |
> |
if (ex == null && t.status < NORMAL) |
493 |
|
ex = t.getException(); |
494 |
|
} |
495 |
|
} |
525 |
|
*/ |
526 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
527 |
|
setCompletion(CANCELLED); |
528 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
528 |
> |
return status == CANCELLED; |
529 |
|
} |
530 |
|
|
531 |
|
/** |
532 |
< |
* Cancels, ignoring any exceptions it throws. Used during worker |
533 |
< |
* and pool shutdown. |
532 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
533 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
534 |
> |
* exceptions, but if it does anyway, we have no recourse during |
535 |
> |
* shutdown, so guard against this case. |
536 |
|
*/ |
537 |
|
final void cancelIgnoringExceptions() { |
538 |
|
try { |
542 |
|
} |
543 |
|
|
544 |
|
/** |
545 |
< |
* Cancels ignoring exceptions if worker is terminating |
545 |
> |
* Cancels if current thread is a terminating worker thread, |
546 |
> |
* ignoring any exceptions thrown by cancel. |
547 |
|
*/ |
548 |
< |
private void cancelIfTerminating() { |
548 |
> |
final void cancelIfTerminating() { |
549 |
|
Thread t = Thread.currentThread(); |
550 |
|
if ((t instanceof ForkJoinWorkerThread) && |
551 |
|
((ForkJoinWorkerThread) t).isTerminating()) { |
561 |
|
} |
562 |
|
|
563 |
|
public final boolean isCancelled() { |
564 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
564 |
> |
return status == CANCELLED; |
565 |
|
} |
566 |
|
|
567 |
|
/** |
570 |
|
* @return {@code true} if this task threw an exception or was cancelled |
571 |
|
*/ |
572 |
|
public final boolean isCompletedAbnormally() { |
573 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
573 |
> |
return status < NORMAL; |
574 |
|
} |
575 |
|
|
576 |
|
/** |
581 |
|
* exception and was not cancelled |
582 |
|
*/ |
583 |
|
public final boolean isCompletedNormally() { |
584 |
< |
return (status & COMPLETION_MASK) == NORMAL; |
584 |
> |
return status == NORMAL; |
585 |
|
} |
586 |
|
|
587 |
|
/** |
592 |
|
* @return the exception, or {@code null} if none |
593 |
|
*/ |
594 |
|
public final Throwable getException() { |
595 |
< |
int s = status & COMPLETION_MASK; |
595 |
> |
int s = status; |
596 |
|
return ((s >= NORMAL) ? null : |
597 |
|
(s == CANCELLED) ? new CancellationException() : |
598 |
|
exceptionMap.get(this)); |
613 |
|
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
614 |
|
*/ |
615 |
|
public void completeExceptionally(Throwable ex) { |
616 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
617 |
< |
(ex instanceof Error) ? ex : |
618 |
< |
new RuntimeException(ex)); |
616 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
617 |
> |
(ex instanceof Error) ? ex : |
618 |
> |
new RuntimeException(ex)); |
619 |
|
} |
620 |
|
|
621 |
|
/** |
622 |
|
* Completes this task, and if not already aborted or cancelled, |
623 |
< |
* returning a {@code null} result upon {@code join} and related |
624 |
< |
* operations. This method may be used to provide results for |
625 |
< |
* asynchronous tasks, or to provide alternative handling for |
626 |
< |
* tasks that would not otherwise complete normally. Its use in |
627 |
< |
* other situations is discouraged. This method is |
628 |
< |
* overridable, but overridden versions must invoke {@code super} |
629 |
< |
* implementation to maintain guarantees. |
623 |
> |
* returning the given value as the result of subsequent |
624 |
> |
* invocations of {@code join} and related operations. This method |
625 |
> |
* may be used to provide results for asynchronous tasks, or to |
626 |
> |
* provide alternative handling for tasks that would not otherwise |
627 |
> |
* complete normally. Its use in other situations is |
628 |
> |
* discouraged. This method is overridable, but overridden |
629 |
> |
* versions must invoke {@code super} implementation to maintain |
630 |
> |
* guarantees. |
631 |
|
* |
632 |
|
* @param value the result value for this task |
633 |
|
*/ |
635 |
|
try { |
636 |
|
setRawResult(value); |
637 |
|
} catch (Throwable rex) { |
638 |
< |
setDoneExceptionally(rex); |
638 |
> |
setExceptionalCompletion(rex); |
639 |
|
return; |
640 |
|
} |
641 |
|
setCompletion(NORMAL); |
642 |
|
} |
643 |
|
|
644 |
+ |
/** |
645 |
+ |
* Waits if necessary for the computation to complete, and then |
646 |
+ |
* retrieves its result. |
647 |
+ |
* |
648 |
+ |
* @return the computed result |
649 |
+ |
* @throws CancellationException if the computation was cancelled |
650 |
+ |
* @throws ExecutionException if the computation threw an |
651 |
+ |
* exception |
652 |
+ |
* @throws InterruptedException if the current thread is not a |
653 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
654 |
+ |
*/ |
655 |
|
public final V get() throws InterruptedException, ExecutionException { |
656 |
< |
quietlyJoin(); |
657 |
< |
return reportFutureResult(); |
656 |
> |
int s; |
657 |
> |
if (Thread.currentThread() instanceof ForkJoinWorkerThread) { |
658 |
> |
quietlyJoin(); |
659 |
> |
s = status; |
660 |
> |
} |
661 |
> |
else { |
662 |
> |
while ((s = status) >= 0) { |
663 |
> |
synchronized (this) { // interruptible form of awaitDone |
664 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, |
665 |
> |
s, SIGNAL)) { |
666 |
> |
while (status >= 0) |
667 |
> |
wait(); |
668 |
> |
} |
669 |
> |
} |
670 |
> |
} |
671 |
> |
} |
672 |
> |
if (s < NORMAL) { |
673 |
> |
Throwable ex; |
674 |
> |
if (s == CANCELLED) |
675 |
> |
throw new CancellationException(); |
676 |
> |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
677 |
> |
throw new ExecutionException(ex); |
678 |
> |
} |
679 |
> |
return getRawResult(); |
680 |
|
} |
681 |
|
|
682 |
+ |
/** |
683 |
+ |
* Waits if necessary for at most the given time for the computation |
684 |
+ |
* to complete, and then retrieves its result, if available. |
685 |
+ |
* |
686 |
+ |
* @param timeout the maximum time to wait |
687 |
+ |
* @param unit the time unit of the timeout argument |
688 |
+ |
* @return the computed result |
689 |
+ |
* @throws CancellationException if the computation was cancelled |
690 |
+ |
* @throws ExecutionException if the computation threw an |
691 |
+ |
* exception |
692 |
+ |
* @throws InterruptedException if the current thread is not a |
693 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
694 |
+ |
* @throws TimeoutException if the wait timed out |
695 |
+ |
*/ |
696 |
|
public final V get(long timeout, TimeUnit unit) |
697 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
786 |
– |
long nanos = unit.toNanos(timeout); |
698 |
|
Thread t = Thread.currentThread(); |
699 |
+ |
ForkJoinPool pool; |
700 |
|
if (t instanceof ForkJoinWorkerThread) { |
701 |
|
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
702 |
< |
if (!w.unpushTask(this) || !tryExec()) |
703 |
< |
timedAwaitDone(w, nanos); |
702 |
> |
if (status >= 0 && w.unpushTask(this)) |
703 |
> |
quietlyExec(); |
704 |
> |
pool = w.pool; |
705 |
|
} |
706 |
|
else |
707 |
< |
externalTimedAwaitDone(nanos); |
708 |
< |
return reportTimedFutureResult(); |
709 |
< |
} |
710 |
< |
|
711 |
< |
/** |
712 |
< |
* Possibly executes other tasks until this task {@link #isDone is |
713 |
< |
* done}, then returns the result of the computation. This method |
714 |
< |
* may be more efficient than {@code join}, but is only applicable |
715 |
< |
* when there are no potential dependencies between continuation |
716 |
< |
* of the current task and that of any other task that might be |
717 |
< |
* executed while helping. (This usually holds for pure |
718 |
< |
* divide-and-conquer tasks). |
719 |
< |
* |
720 |
< |
* <p>This method may be invoked only from within {@code |
721 |
< |
* ForkJoinTask} computations (as may be determined using method |
722 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
723 |
< |
* result in exceptions or errors, possibly including {@code |
724 |
< |
* ClassCastException}. |
725 |
< |
* |
726 |
< |
* @return the computed result |
727 |
< |
*/ |
728 |
< |
public final V helpJoin() { |
729 |
< |
quietlyHelpJoin(); |
730 |
< |
return reportResult(); |
731 |
< |
} |
732 |
< |
|
733 |
< |
/** |
734 |
< |
* Possibly executes other tasks until this task {@link #isDone is |
735 |
< |
* done}. This method may be useful when processing collections |
823 |
< |
* of tasks when some have been cancelled or otherwise known to |
824 |
< |
* have aborted. |
825 |
< |
* |
826 |
< |
* <p>This method may be invoked only from within {@code |
827 |
< |
* ForkJoinTask} computations (as may be determined using method |
828 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
829 |
< |
* result in exceptions or errors, possibly including {@code |
830 |
< |
* ClassCastException}. |
831 |
< |
*/ |
832 |
< |
public final void quietlyHelpJoin() { |
833 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
834 |
< |
if (!w.unpushTask(this) || !tryExec()) { |
835 |
< |
for (;;) { |
836 |
< |
ForkJoinTask<?> t; |
837 |
< |
if (status < 0) |
838 |
< |
return; |
839 |
< |
else if ((t = w.scanWhileJoining(this)) != null) |
840 |
< |
t.tryExec(); |
841 |
< |
else if (status < 0) |
842 |
< |
return; |
843 |
< |
else if (w.pool.preBlockHelpingJoin(this)) { |
844 |
< |
while (status >= 0) { // variant of awaitDone |
707 |
> |
pool = null; |
708 |
> |
/* |
709 |
> |
* Timed wait loop intermixes cases for FJ (pool != null) and |
710 |
> |
* non FJ threads. For FJ, decrement pool count but don't try |
711 |
> |
* for replacement; increment count on completion. For non-FJ, |
712 |
> |
* deal with interrupts. This is messy, but a little less so |
713 |
> |
* than is splitting the FJ and nonFJ cases. |
714 |
> |
*/ |
715 |
> |
boolean interrupted = false; |
716 |
> |
boolean dec = false; // true if pool count decremented |
717 |
> |
long nanos = unit.toNanos(timeout); |
718 |
> |
for (;;) { |
719 |
> |
if (pool == null && Thread.interrupted()) { |
720 |
> |
interrupted = true; |
721 |
> |
break; |
722 |
> |
} |
723 |
> |
int s = status; |
724 |
> |
if (s < 0) |
725 |
> |
break; |
726 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) { |
727 |
> |
long startTime = System.nanoTime(); |
728 |
> |
long nt; // wait time |
729 |
> |
while (status >= 0 && |
730 |
> |
(nt = nanos - (System.nanoTime() - startTime)) > 0) { |
731 |
> |
if (pool != null && !dec) |
732 |
> |
dec = pool.tryDecrementRunningCount(); |
733 |
> |
else { |
734 |
> |
long ms = nt / 1000000; |
735 |
> |
int ns = (int) (nt % 1000000); |
736 |
|
try { |
737 |
< |
synchronized(this) { |
737 |
> |
synchronized (this) { |
738 |
|
if (status >= 0) |
739 |
< |
wait(); |
849 |
< |
else { |
850 |
< |
notifyAll(); |
851 |
< |
break; |
852 |
< |
} |
739 |
> |
wait(ms, ns); |
740 |
|
} |
741 |
|
} catch (InterruptedException ie) { |
742 |
< |
cancelIfTerminating(); |
742 |
> |
if (pool != null) |
743 |
> |
cancelIfTerminating(); |
744 |
> |
else { |
745 |
> |
interrupted = true; |
746 |
> |
break; |
747 |
> |
} |
748 |
|
} |
749 |
|
} |
858 |
– |
return; |
750 |
|
} |
751 |
+ |
break; |
752 |
|
} |
753 |
|
} |
754 |
+ |
if (pool != null && dec) |
755 |
+ |
pool.incrementRunningCount(); |
756 |
+ |
if (interrupted) |
757 |
+ |
throw new InterruptedException(); |
758 |
+ |
int es = status; |
759 |
+ |
if (es != NORMAL) { |
760 |
+ |
Throwable ex; |
761 |
+ |
if (es == CANCELLED) |
762 |
+ |
throw new CancellationException(); |
763 |
+ |
if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
764 |
+ |
throw new ExecutionException(ex); |
765 |
+ |
throw new TimeoutException(); |
766 |
+ |
} |
767 |
+ |
return getRawResult(); |
768 |
|
} |
769 |
|
|
770 |
|
/** |
771 |
< |
* Joins this task, without returning its result or throwing an |
771 |
> |
* Joins this task, without returning its result or throwing its |
772 |
|
* exception. This method may be useful when processing |
773 |
|
* collections of tasks when some have been cancelled or otherwise |
774 |
|
* known to have aborted. |
775 |
|
*/ |
776 |
|
public final void quietlyJoin() { |
777 |
< |
Thread t = Thread.currentThread(); |
778 |
< |
if (t instanceof ForkJoinWorkerThread) { |
777 |
> |
Thread t; |
778 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
779 |
|
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
780 |
< |
if (!w.unpushTask(this) || !tryExec()) |
781 |
< |
awaitDone(w); |
780 |
> |
if (status >= 0) { |
781 |
> |
if (w.unpushTask(this)) { |
782 |
> |
boolean completed; |
783 |
> |
try { |
784 |
> |
completed = exec(); |
785 |
> |
} catch (Throwable rex) { |
786 |
> |
setExceptionalCompletion(rex); |
787 |
> |
return; |
788 |
> |
} |
789 |
> |
if (completed) { |
790 |
> |
setCompletion(NORMAL); |
791 |
> |
return; |
792 |
> |
} |
793 |
> |
} |
794 |
> |
w.joinTask(this); |
795 |
> |
} |
796 |
|
} |
797 |
|
else |
798 |
|
externalAwaitDone(); |
800 |
|
|
801 |
|
/** |
802 |
|
* Commences performing this task and awaits its completion if |
803 |
< |
* necessary, without returning its result or throwing an |
804 |
< |
* exception. This method may be useful when processing |
885 |
< |
* collections of tasks when some have been cancelled or otherwise |
886 |
< |
* known to have aborted. |
803 |
> |
* necessary, without returning its result or throwing its |
804 |
> |
* exception. |
805 |
|
*/ |
806 |
|
public final void quietlyInvoke() { |
807 |
< |
if (!tryExec()) |
808 |
< |
quietlyJoin(); |
807 |
> |
if (status >= 0) { |
808 |
> |
boolean completed; |
809 |
> |
try { |
810 |
> |
completed = exec(); |
811 |
> |
} catch (Throwable rex) { |
812 |
> |
setExceptionalCompletion(rex); |
813 |
> |
return; |
814 |
> |
} |
815 |
> |
if (completed) |
816 |
> |
setCompletion(NORMAL); |
817 |
> |
else |
818 |
> |
quietlyJoin(); |
819 |
> |
} |
820 |
|
} |
821 |
|
|
822 |
|
/** |
848 |
|
* pre-constructed trees of subtasks in loops. |
849 |
|
*/ |
850 |
|
public void reinitialize() { |
851 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
851 |
> |
if (status == EXCEPTIONAL) |
852 |
|
exceptionMap.remove(this); |
853 |
|
status = 0; |
854 |
|
} |
1138 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1139 |
|
|
1140 |
|
/** |
1141 |
< |
* Saves the state to a stream. |
1141 |
> |
* Saves the state to a stream (that is, serializes it). |
1142 |
|
* |
1143 |
|
* @serialData the current run status and the exception thrown |
1144 |
|
* during execution, or {@code null} if none |
1151 |
|
} |
1152 |
|
|
1153 |
|
/** |
1154 |
< |
* Reconstitutes the instance from a stream. |
1154 |
> |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1155 |
|
* |
1156 |
|
* @param s the stream |
1157 |
|
*/ |
1158 |
|
private void readObject(java.io.ObjectInputStream s) |
1159 |
|
throws java.io.IOException, ClassNotFoundException { |
1160 |
|
s.defaultReadObject(); |
1232 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1233 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1161 |
|
Object ex = s.readObject(); |
1162 |
|
if (ex != null) |
1163 |
< |
setDoneExceptionally((Throwable) ex); |
1163 |
> |
setExceptionalCompletion((Throwable) ex); |
1164 |
|
} |
1165 |
|
|
1166 |
|
// Unsafe mechanics |