12 |
|
import java.util.Collection; |
13 |
|
import java.util.Collections; |
14 |
|
import java.util.List; |
15 |
+ |
import java.util.RandomAccess; |
16 |
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import java.util.Map; |
17 |
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import java.util.WeakHashMap; |
18 |
|
|
55 |
|
* restriction is in part enforced by not permitting checked |
56 |
|
* exceptions such as {@code IOExceptions} to be thrown. However, |
57 |
|
* computations may still encounter unchecked exceptions, that are |
58 |
< |
* rethrown to callers attempting join them. These exceptions may |
59 |
< |
* additionally include RejectedExecutionExceptions stemming from |
60 |
< |
* internal resource exhaustion such as failure to allocate internal |
61 |
< |
* task queues. |
58 |
> |
* rethrown to callers attempting to join them. These exceptions may |
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 |
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* results of a task is {@link #join}, but there are several variants: |
65 |
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* The {@link Future#get} methods support interruptible and/or timed |
66 |
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* 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 |
70 |
< |
* equivalent to {@code fork(); join()} but always attempts to |
71 |
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* begin execution in the current thread. The "<em>quiet</em>" forms |
72 |
< |
* of these methods do not extract results or report exceptions. These |
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 |
71 |
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* may be useful when a set of tasks are being executed, and you need |
72 |
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* to delay processing of results or exceptions until all complete. |
73 |
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* Method {@code invokeAll} (available in multiple versions) |
74 |
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* performs the most common form of parallel invocation: forking a set |
75 |
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* of tasks and joining them all. |
76 |
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* |
77 |
+ |
* <p>The execution status of tasks may be queried at several levels |
78 |
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* of detail: {@link #isDone} is true if a task completed in any way |
79 |
+ |
* (including the case where a task was cancelled without executing); |
80 |
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* {@link #isCompletedNormally} is true if a task completed without |
81 |
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* cancellation or encountering an exception; {@link #isCancelled} is |
82 |
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* true if the task was cancelled (in which case {@link #getException} |
83 |
+ |
* returns a {@link java.util.concurrent.CancellationException}); and |
84 |
+ |
* {@link #isCompletedAbnormally} is true if a task was either |
85 |
+ |
* cancelled or encountered an exception, in which case {@link |
86 |
+ |
* #getException} will return either the encountered exception or |
87 |
+ |
* {@link java.util.concurrent.CancellationException}. |
88 |
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* |
89 |
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* <p>The ForkJoinTask class is not usually directly subclassed. |
90 |
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* Instead, you subclass one of the abstract classes that support a |
91 |
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* particular style of fork/join processing, typically {@link |
95 |
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* established in a constructor, and then defines a {@code compute} |
96 |
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* method that somehow uses the control methods supplied by this base |
97 |
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* class. While these methods have {@code public} access (to allow |
98 |
< |
* instances of different task subclasses to call each others |
98 |
> |
* instances of different task subclasses to call each other's |
99 |
|
* methods), some of them may only be called from within other |
100 |
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* ForkJoinTasks (as may be determined using method {@link |
101 |
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* #inForkJoinPool}). Attempts to invoke them in other contexts |
102 |
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* result in exceptions or errors, possibly including |
103 |
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* ClassCastException. |
104 |
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* |
105 |
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* <p>Most base support methods are {@code final} because their |
106 |
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* implementations are intrinsically tied to the underlying |
107 |
< |
* lightweight task scheduling framework, and so cannot be overridden. |
108 |
< |
* Developers creating new basic styles of fork/join processing should |
109 |
< |
* minimally implement {@code protected} methods |
110 |
< |
* {@link #exec}, {@link #setRawResult}, and |
111 |
< |
* {@link #getRawResult}, while also introducing an abstract |
112 |
< |
* computational method that can be implemented in its subclasses, |
113 |
< |
* possibly relying on other {@code protected} methods provided |
104 |
< |
* by this class. |
105 |
> |
* <p>Most base support methods are {@code final}, to prevent |
106 |
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* overriding of implementations that are intrinsically tied to the |
107 |
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* underlying lightweight task scheduling framework. Developers |
108 |
> |
* creating new basic styles of fork/join processing should minimally |
109 |
> |
* implement {@code protected} methods {@link #exec}, {@link |
110 |
> |
* #setRawResult}, and {@link #getRawResult}, while also introducing |
111 |
> |
* an abstract computational method that can be implemented in its |
112 |
> |
* subclasses, possibly relying on other {@code protected} methods |
113 |
> |
* provided by this class. |
114 |
|
* |
115 |
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* <p>ForkJoinTasks should perform relatively small amounts of |
116 |
< |
* computations, otherwise splitting into smaller tasks. As a very |
117 |
< |
* rough rule of thumb, a task should perform more than 100 and less |
118 |
< |
* than 10000 basic computational steps. If tasks are too big, then |
119 |
< |
* parallelism cannot improve throughput. If too small, then memory |
120 |
< |
* and internal task maintenance overhead may overwhelm processing. |
116 |
> |
* computation. Large tasks should be split into smaller subtasks, |
117 |
> |
* usually via recursive decomposition. As a very rough rule of thumb, |
118 |
> |
* a task should perform more than 100 and less than 10000 basic |
119 |
> |
* computational steps. If tasks are too big, then parallelism cannot |
120 |
> |
* improve throughput. If too small, then memory and internal task |
121 |
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* maintenance overhead may overwhelm processing. |
122 |
|
* |
123 |
< |
* <p>This class provides {@code adapt} methods for {@link |
124 |
< |
* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that |
125 |
< |
* may be of use when mixing execution of ForkJoinTasks with other |
126 |
< |
* kinds of tasks. When all tasks are of this form, consider using a |
117 |
< |
* pool in {@link ForkJoinPool#setAsyncMode}. |
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 are |
126 |
> |
* of this form, consider using a pool constructed in <em>asyncMode</em>. |
127 |
|
* |
128 |
< |
* <p>ForkJoinTasks are {@code Serializable}, which enables them |
129 |
< |
* to be used in extensions such as remote execution frameworks. It is |
130 |
< |
* in general sensible to serialize tasks only before or after, but |
131 |
< |
* not during execution. Serialization is not relied on during |
123 |
< |
* execution itself. |
128 |
> |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
129 |
> |
* used in extensions such as remote execution frameworks. It is |
130 |
> |
* sensible to serialize tasks only before or after, but not during, |
131 |
> |
* execution. Serialization is not relied on during execution itself. |
132 |
|
* |
133 |
|
* @since 1.7 |
134 |
|
* @author Doug Lea |
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 |
> |
* COMPLETED. 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; |
154 |
< |
static final int SIGNAL_MASK = 0x0000ffff; |
155 |
< |
static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
156 |
< |
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 |
171 |
< |
|
172 |
< |
/** |
173 |
< |
* Gets current worker thread, or null if not a worker thread. |
174 |
< |
*/ |
175 |
< |
static ForkJoinWorkerThread getWorker() { |
176 |
< |
Thread t = Thread.currentThread(); |
177 |
< |
return ((t instanceof ForkJoinWorkerThread) ? |
178 |
< |
(ForkJoinWorkerThread) t : null); |
179 |
< |
} |
180 |
< |
|
181 |
< |
final boolean casStatus(int cmp, int val) { |
182 |
< |
return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val); |
183 |
< |
} |
188 |
> |
// Maintaining completion status |
189 |
|
|
190 |
|
/** |
191 |
< |
* Workaround for not being able to rethrow unchecked exceptions. |
192 |
< |
*/ |
188 |
< |
static void rethrowException(Throwable ex) { |
189 |
< |
if (ex != null) |
190 |
< |
UNSAFE.throwException(ex); |
191 |
< |
} |
192 |
< |
|
193 |
< |
// Setting completion status |
194 |
< |
|
195 |
< |
/** |
196 |
< |
* 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) { |
207 |
< |
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
208 |
< |
pool.updateRunningCount(s); |
209 |
< |
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 |
|
} |
212 |
– |
else |
213 |
– |
externallySetCompletion(completion); |
205 |
|
} |
206 |
|
|
207 |
|
/** |
208 |
< |
* Version of setCompletion for non-FJ threads. Leaves signal |
209 |
< |
* bits for unblocked threads to adjust, and always notifies. |
219 |
< |
*/ |
220 |
< |
private void externallySetCompletion(int completion) { |
221 |
< |
int s; |
222 |
< |
do {} while ((s = status) >= 0 && |
223 |
< |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
224 |
< |
synchronized (this) { notifyAll(); } |
225 |
< |
} |
226 |
< |
|
227 |
< |
/** |
228 |
< |
* Sets status to indicate normal completion. |
229 |
< |
*/ |
230 |
< |
final void setNormalCompletion() { |
231 |
< |
// Try typical fast case -- single CAS, no signal, not already done. |
232 |
< |
// Manually expand casStatus to improve chances of inlining it |
233 |
< |
if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
234 |
< |
setCompletion(NORMAL); |
235 |
< |
} |
236 |
< |
|
237 |
< |
// internal waiting and notification |
238 |
< |
|
239 |
< |
/** |
240 |
< |
* Performs the actual monitor wait for awaitDone. |
208 |
> |
* Record exception and set exceptional completion |
209 |
> |
* @return status on exit |
210 |
|
*/ |
211 |
< |
private void doAwaitDone() { |
212 |
< |
// Minimize lock bias and in/de-flation effects by maximizing |
213 |
< |
// chances of waiting inside sync |
245 |
< |
try { |
246 |
< |
while (status >= 0) |
247 |
< |
synchronized (this) { if (status >= 0) wait(); } |
248 |
< |
} catch (InterruptedException ie) { |
249 |
< |
onInterruptedWait(); |
250 |
< |
} |
211 |
> |
private void setExceptionalCompletion(Throwable rex) { |
212 |
> |
exceptionMap.put(this, rex); |
213 |
> |
setCompletion(EXCEPTIONAL); |
214 |
|
} |
215 |
|
|
216 |
|
/** |
217 |
< |
* Performs the actual timed monitor wait for awaitDone. |
217 |
> |
* Blocks a worker thread until completion. Called only by pool. |
218 |
|
*/ |
219 |
< |
private void doAwaitDone(long startTime, long nanos) { |
220 |
< |
synchronized (this) { |
219 |
> |
final void internalAwaitDone() { |
220 |
> |
int s; // the odd construction reduces lock bias effects |
221 |
> |
while ((s = status) >= 0) { |
222 |
|
try { |
223 |
< |
while (status >= 0) { |
224 |
< |
long nt = nanos - (System.nanoTime() - startTime); |
225 |
< |
if (nt <= 0) |
262 |
< |
break; |
263 |
< |
wait(nt / 1000000, (int) (nt % 1000000)); |
223 |
> |
synchronized(this) { |
224 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
225 |
> |
wait(); |
226 |
|
} |
227 |
|
} catch (InterruptedException ie) { |
228 |
< |
onInterruptedWait(); |
228 |
> |
cancelIfTerminating(); |
229 |
|
} |
230 |
|
} |
231 |
|
} |
232 |
|
|
271 |
– |
// Awaiting completion |
272 |
– |
|
233 |
|
/** |
234 |
< |
* Sets status to indicate there is joiner, then waits for join, |
275 |
< |
* surrounded with pool notifications. |
276 |
< |
* |
277 |
< |
* @return status upon exit |
234 |
> |
* Blocks a non-worker-thread until completion. |
235 |
|
*/ |
236 |
< |
private int awaitDone(ForkJoinWorkerThread w, |
280 |
< |
boolean maintainParallelism) { |
281 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
236 |
> |
private void externalAwaitDone() { |
237 |
|
int s; |
238 |
|
while ((s = status) >= 0) { |
239 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
240 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
241 |
< |
doAwaitDone(); |
242 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
243 |
< |
adjustPoolCountsOnUnblock(pool); |
244 |
< |
break; |
245 |
< |
} |
246 |
< |
} |
247 |
< |
return s; |
248 |
< |
} |
249 |
< |
|
250 |
< |
/** |
296 |
< |
* Timed version of awaitDone |
297 |
< |
* |
298 |
< |
* @return status upon exit |
299 |
< |
*/ |
300 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
301 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
302 |
< |
int s; |
303 |
< |
while ((s = status) >= 0) { |
304 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
305 |
< |
long startTime = System.nanoTime(); |
306 |
< |
if (pool == null || !pool.preJoin(this, false)) |
307 |
< |
doAwaitDone(startTime, nanos); |
308 |
< |
if ((s = status) >= 0) { |
309 |
< |
adjustPoolCountsOnCancelledWait(pool); |
310 |
< |
s = status; |
311 |
< |
} |
312 |
< |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
313 |
< |
adjustPoolCountsOnUnblock(pool); |
314 |
< |
break; |
315 |
< |
} |
316 |
< |
} |
317 |
< |
return s; |
318 |
< |
} |
319 |
< |
|
320 |
< |
/** |
321 |
< |
* Notifies pool that thread is unblocked. Called by signalled |
322 |
< |
* threads when woken by non-FJ threads (which is atypical). |
323 |
< |
*/ |
324 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
325 |
< |
int s; |
326 |
< |
do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
327 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
328 |
< |
pool.updateRunningCount(s); |
329 |
< |
} |
330 |
< |
|
331 |
< |
/** |
332 |
< |
* Notifies pool to adjust counts on cancelled or timed out wait. |
333 |
< |
*/ |
334 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
335 |
< |
if (pool != null) { |
336 |
< |
int s; |
337 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
338 |
< |
if (casStatus(s, s - 1)) { |
339 |
< |
pool.updateRunningCount(1); |
239 |
> |
synchronized(this) { |
240 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){ |
241 |
> |
boolean interrupted = false; |
242 |
> |
while (status >= 0) { |
243 |
> |
try { |
244 |
> |
wait(); |
245 |
> |
} catch (InterruptedException ie) { |
246 |
> |
interrupted = true; |
247 |
> |
} |
248 |
> |
} |
249 |
> |
if (interrupted) |
250 |
> |
Thread.currentThread().interrupt(); |
251 |
|
break; |
252 |
|
} |
253 |
|
} |
255 |
|
} |
256 |
|
|
257 |
|
/** |
258 |
< |
* Handles interruptions during waits. |
259 |
< |
*/ |
260 |
< |
private void onInterruptedWait() { |
350 |
< |
ForkJoinWorkerThread w = getWorker(); |
351 |
< |
if (w == null) |
352 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
353 |
< |
else if (w.isTerminating()) |
354 |
< |
cancelIgnoringExceptions(); |
355 |
< |
// else if FJworker, ignore interrupt |
356 |
< |
} |
357 |
< |
|
358 |
< |
// Recording and reporting exceptions |
359 |
< |
|
360 |
< |
private void setDoneExceptionally(Throwable rex) { |
361 |
< |
exceptionMap.put(this, rex); |
362 |
< |
setCompletion(EXCEPTIONAL); |
363 |
< |
} |
364 |
< |
|
365 |
< |
/** |
366 |
< |
* Throws the exception associated with status s. |
367 |
< |
* |
368 |
< |
* @throws the exception |
369 |
< |
*/ |
370 |
< |
private void reportException(int s) { |
371 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
372 |
< |
if (s == CANCELLED) |
373 |
< |
throw new CancellationException(); |
374 |
< |
else |
375 |
< |
rethrowException(exceptionMap.get(this)); |
376 |
< |
} |
377 |
< |
} |
378 |
< |
|
379 |
< |
/** |
380 |
< |
* Returns result or throws exception using j.u.c.Future conventions. |
381 |
< |
* Only call when {@code isDone} known to be true. |
382 |
< |
*/ |
383 |
< |
private V reportFutureResult() |
384 |
< |
throws ExecutionException, InterruptedException { |
385 |
< |
int s = status & COMPLETION_MASK; |
386 |
< |
if (s < NORMAL) { |
387 |
< |
Throwable ex; |
388 |
< |
if (s == CANCELLED) |
389 |
< |
throw new CancellationException(); |
390 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
391 |
< |
throw new ExecutionException(ex); |
392 |
< |
if (Thread.interrupted()) |
393 |
< |
throw new InterruptedException(); |
394 |
< |
} |
395 |
< |
return getRawResult(); |
396 |
< |
} |
397 |
< |
|
398 |
< |
/** |
399 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
400 |
< |
* with timeouts. |
401 |
< |
*/ |
402 |
< |
private V reportTimedFutureResult() |
403 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
404 |
< |
Throwable ex; |
405 |
< |
int s = status & COMPLETION_MASK; |
406 |
< |
if (s == NORMAL) |
407 |
< |
return getRawResult(); |
408 |
< |
if (s == CANCELLED) |
409 |
< |
throw new CancellationException(); |
410 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
411 |
< |
throw new ExecutionException(ex); |
412 |
< |
if (Thread.interrupted()) |
413 |
< |
throw new InterruptedException(); |
414 |
< |
throw new TimeoutException(); |
415 |
< |
} |
416 |
< |
|
417 |
< |
// internal execution methods |
418 |
< |
|
419 |
< |
/** |
420 |
< |
* Calls exec, recording completion, and rethrowing exception if |
421 |
< |
* encountered. Caller should normally check status before calling. |
422 |
< |
* |
423 |
< |
* @return true if completed normally |
424 |
< |
*/ |
425 |
< |
private boolean tryExec() { |
426 |
< |
try { // try block must contain only call to exec |
427 |
< |
if (!exec()) |
428 |
< |
return false; |
429 |
< |
} catch (Throwable rex) { |
430 |
< |
setDoneExceptionally(rex); |
431 |
< |
rethrowException(rex); |
432 |
< |
return false; // not reached |
433 |
< |
} |
434 |
< |
setNormalCompletion(); |
435 |
< |
return true; |
436 |
< |
} |
437 |
< |
|
438 |
< |
/** |
439 |
< |
* Main execution method used by worker threads. Invokes |
440 |
< |
* base computation unless already complete. |
258 |
> |
* Unless done, calls exec and records status if completed, but |
259 |
> |
* doesn't wait for completion otherwise. Primary execution method |
260 |
> |
* for ForkJoinWorkerThread. |
261 |
|
*/ |
262 |
|
final void quietlyExec() { |
443 |
– |
if (status >= 0) { |
444 |
– |
try { |
445 |
– |
if (!exec()) |
446 |
– |
return; |
447 |
– |
} catch (Throwable rex) { |
448 |
– |
setDoneExceptionally(rex); |
449 |
– |
return; |
450 |
– |
} |
451 |
– |
setNormalCompletion(); |
452 |
– |
} |
453 |
– |
} |
454 |
– |
|
455 |
– |
/** |
456 |
– |
* Calls exec(), recording but not rethrowing exception. |
457 |
– |
* Caller should normally check status before calling. |
458 |
– |
* |
459 |
– |
* @return true if completed normally |
460 |
– |
*/ |
461 |
– |
private boolean tryQuietlyInvoke() { |
263 |
|
try { |
264 |
< |
if (!exec()) |
265 |
< |
return false; |
264 |
> |
if (status < 0 || !exec()) |
265 |
> |
return; |
266 |
|
} catch (Throwable rex) { |
267 |
< |
setDoneExceptionally(rex); |
268 |
< |
return false; |
468 |
< |
} |
469 |
< |
setNormalCompletion(); |
470 |
< |
return true; |
471 |
< |
} |
472 |
< |
|
473 |
< |
/** |
474 |
< |
* Cancels, ignoring any exceptions it throws. |
475 |
< |
*/ |
476 |
< |
final void cancelIgnoringExceptions() { |
477 |
< |
try { |
478 |
< |
cancel(false); |
479 |
< |
} catch (Throwable ignore) { |
267 |
> |
setExceptionalCompletion(rex); |
268 |
> |
return; |
269 |
|
} |
270 |
< |
} |
482 |
< |
|
483 |
< |
/** |
484 |
< |
* Main implementation of helpJoin |
485 |
< |
*/ |
486 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
487 |
< |
int s; |
488 |
< |
ForkJoinTask<?> t; |
489 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
490 |
< |
t.quietlyExec(); |
491 |
< |
return (s >= 0) ? awaitDone(w, false) : s; // block if no work |
270 |
> |
setCompletion(NORMAL); // must be outside try block |
271 |
|
} |
272 |
|
|
273 |
|
// public methods |
275 |
|
/** |
276 |
|
* Arranges to asynchronously execute this task. While it is not |
277 |
|
* necessarily enforced, it is a usage error to fork a task more |
278 |
< |
* than once unless it has completed and been reinitialized. This |
279 |
< |
* method may be invoked only from within ForkJoinTask |
280 |
< |
* computations (as may be determined using method {@link |
281 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
282 |
< |
* in exceptions or errors, possibly including ClassCastException. |
278 |
> |
* than once unless it has completed and been reinitialized. |
279 |
> |
* Subsequent modifications to the state of this task or any data |
280 |
> |
* it operates on are not necessarily consistently observable by |
281 |
> |
* any thread other than the one executing it unless preceded by a |
282 |
> |
* call to {@link #join} or related methods, or a call to {@link |
283 |
> |
* #isDone} returning {@code true}. |
284 |
> |
* |
285 |
> |
* <p>This method may be invoked only from within {@code |
286 |
> |
* ForkJoinTask} computations (as may be determined using method |
287 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
288 |
> |
* result in exceptions or errors, possibly including {@code |
289 |
> |
* ClassCastException}. |
290 |
|
* |
291 |
< |
* @return {@code this}, to simplify usage. |
291 |
> |
* @return {@code this}, to simplify usage |
292 |
|
*/ |
293 |
|
public final ForkJoinTask<V> fork() { |
294 |
|
((ForkJoinWorkerThread) Thread.currentThread()) |
297 |
|
} |
298 |
|
|
299 |
|
/** |
300 |
< |
* Returns the result of the computation when it is ready. |
301 |
< |
* This method differs from {@code get} in that abnormal |
302 |
< |
* completion results in RuntimeExceptions or Errors, not |
303 |
< |
* ExecutionExceptions. |
300 |
> |
* Returns the result of the computation when it {@link #isDone is done}. |
301 |
> |
* This method differs from {@link #get()} in that |
302 |
> |
* abnormal completion results in {@code RuntimeException} or |
303 |
> |
* {@code Error}, not {@code ExecutionException}. |
304 |
|
* |
305 |
|
* @return the computed result |
306 |
|
*/ |
307 |
|
public final V join() { |
308 |
< |
ForkJoinWorkerThread w = getWorker(); |
309 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
310 |
< |
reportException(awaitDone(w, true)); |
308 |
> |
quietlyJoin(); |
309 |
> |
Throwable ex; |
310 |
> |
if (status < NORMAL && (ex = getException()) != null) |
311 |
> |
UNSAFE.throwException(ex); |
312 |
|
return getRawResult(); |
313 |
|
} |
314 |
|
|
315 |
|
/** |
316 |
|
* Commences performing this task, awaits its completion if |
317 |
< |
* necessary, and return its result. |
317 |
> |
* necessary, and return its result, or throws an (unchecked) |
318 |
> |
* exception if the underlying computation did so. |
319 |
|
* |
532 |
– |
* @throws Throwable (a RuntimeException, Error, or unchecked |
533 |
– |
* exception) if the underlying computation did so |
320 |
|
* @return the computed result |
321 |
|
*/ |
322 |
|
public final V invoke() { |
323 |
< |
if (status >= 0 && tryExec()) |
324 |
< |
return getRawResult(); |
325 |
< |
else |
326 |
< |
return join(); |
323 |
> |
quietlyInvoke(); |
324 |
> |
Throwable ex; |
325 |
> |
if (status < NORMAL && (ex = getException()) != null) |
326 |
> |
UNSAFE.throwException(ex); |
327 |
> |
return getRawResult(); |
328 |
|
} |
329 |
|
|
330 |
|
/** |
331 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
332 |
< |
* each task or an exception is encountered. This method may be |
333 |
< |
* invoked only from within ForkJoinTask computations (as may be |
334 |
< |
* determined using method {@link #inForkJoinPool}). Attempts to |
335 |
< |
* invoke in other contexts result in exceptions or errors, |
336 |
< |
* possibly including ClassCastException. |
332 |
> |
* each task or an (unchecked) exception is encountered, in which |
333 |
> |
* case the exception is rethrown. If either task encounters an |
334 |
> |
* exception, the other one may be, but is not guaranteed to be, |
335 |
> |
* cancelled. If both tasks throw an exception, then this method |
336 |
> |
* throws one of them. The individual status of each task may be |
337 |
> |
* checked using {@link #getException()} and related methods. |
338 |
> |
* |
339 |
> |
* <p>This method may be invoked only from within {@code |
340 |
> |
* ForkJoinTask} computations (as may be determined using method |
341 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
342 |
> |
* result in exceptions or errors, possibly including {@code |
343 |
> |
* ClassCastException}. |
344 |
|
* |
345 |
|
* @param t1 the first task |
346 |
|
* @param t2 the second task |
347 |
|
* @throws NullPointerException if any task is null |
554 |
– |
* @throws RuntimeException or Error if a task did so |
348 |
|
*/ |
349 |
< |
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
349 |
> |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
350 |
|
t2.fork(); |
351 |
|
t1.invoke(); |
352 |
|
t2.join(); |
354 |
|
|
355 |
|
/** |
356 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
357 |
< |
* each task or an exception is encountered. If any task |
358 |
< |
* encounters an exception, others may be, but are not guaranteed |
359 |
< |
* to be, cancelled. This method may be invoked only from within |
360 |
< |
* ForkJoinTask computations (as may be determined using method |
361 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
362 |
< |
* result in exceptions or errors, possibly including |
363 |
< |
* ClassCastException. |
364 |
< |
* |
365 |
< |
* Overloadings of this method exist for the special cases |
366 |
< |
* of one to four arguments. |
357 |
> |
* each task or an (unchecked) exception is encountered, in which |
358 |
> |
* case the exception is rethrown. If any task encounters an |
359 |
> |
* exception, others may be, but are not guaranteed to be, |
360 |
> |
* cancelled. If more than one task encounters an exception, then |
361 |
> |
* this method throws any one of these exceptions. The individual |
362 |
> |
* status of each task may be checked using {@link #getException()} |
363 |
> |
* and related methods. |
364 |
> |
* |
365 |
> |
* <p>This method may be invoked only from within {@code |
366 |
> |
* ForkJoinTask} computations (as may be determined using method |
367 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
368 |
> |
* result in exceptions or errors, possibly including {@code |
369 |
> |
* ClassCastException}. |
370 |
|
* |
371 |
|
* @param tasks the tasks |
372 |
< |
* @throws NullPointerException if tasks or any element are null |
577 |
< |
* @throws RuntimeException or Error if any task did so |
372 |
> |
* @throws NullPointerException if any task is null |
373 |
|
*/ |
374 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
375 |
|
Throwable ex = null; |
384 |
|
t.fork(); |
385 |
|
else { |
386 |
|
t.quietlyInvoke(); |
387 |
< |
if (ex == null) |
387 |
> |
if (ex == null && t.status < NORMAL) |
388 |
|
ex = t.getException(); |
389 |
|
} |
390 |
|
} |
395 |
|
t.cancel(false); |
396 |
|
else { |
397 |
|
t.quietlyJoin(); |
398 |
< |
if (ex == null) |
398 |
> |
if (ex == null && t.status < NORMAL) |
399 |
|
ex = t.getException(); |
400 |
|
} |
401 |
|
} |
402 |
|
} |
403 |
|
if (ex != null) |
404 |
< |
rethrowException(ex); |
404 |
> |
UNSAFE.throwException(ex); |
405 |
|
} |
406 |
|
|
407 |
|
/** |
408 |
< |
* Forks all tasks in the collection, returning when {@code |
409 |
< |
* isDone} holds for each task or an exception is encountered. If |
410 |
< |
* any task encounters an exception, others may be, but are not |
411 |
< |
* guaranteed to be, cancelled. This method may be invoked only |
412 |
< |
* from within ForkJoinTask computations (as may be determined |
413 |
< |
* using method {@link #inForkJoinPool}). Attempts to invoke in |
414 |
< |
* other contexts result in exceptions or errors, possibly |
415 |
< |
* including ClassCastException. |
408 |
> |
* Forks all tasks in the specified collection, returning when |
409 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
410 |
> |
* is encountered. If any task encounters an exception, others |
411 |
> |
* may be, but are not guaranteed to be, cancelled. If more than |
412 |
> |
* one task encounters an exception, then this method throws any |
413 |
> |
* one of these exceptions. The individual status of each task |
414 |
> |
* may be checked using {@link #getException()} and related |
415 |
> |
* methods. The behavior of this operation is undefined if the |
416 |
> |
* specified collection is modified while the operation is in |
417 |
> |
* progress. |
418 |
> |
* |
419 |
> |
* <p>This method may be invoked only from within {@code |
420 |
> |
* ForkJoinTask} computations (as may be determined using method |
421 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
422 |
> |
* result in exceptions or errors, possibly including {@code |
423 |
> |
* ClassCastException}. |
424 |
|
* |
425 |
|
* @param tasks the collection of tasks |
426 |
|
* @return the tasks argument, to simplify usage |
427 |
|
* @throws NullPointerException if tasks or any element are null |
625 |
– |
* @throws RuntimeException or Error if any task did so |
428 |
|
*/ |
429 |
|
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
430 |
< |
if (!(tasks instanceof List<?>)) { |
430 |
> |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
431 |
|
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
432 |
|
return tasks; |
433 |
|
} |
446 |
|
t.fork(); |
447 |
|
else { |
448 |
|
t.quietlyInvoke(); |
449 |
< |
if (ex == null) |
449 |
> |
if (ex == null && t.status < NORMAL) |
450 |
|
ex = t.getException(); |
451 |
|
} |
452 |
|
} |
457 |
|
t.cancel(false); |
458 |
|
else { |
459 |
|
t.quietlyJoin(); |
460 |
< |
if (ex == null) |
460 |
> |
if (ex == null && t.status < NORMAL) |
461 |
|
ex = t.getException(); |
462 |
|
} |
463 |
|
} |
464 |
|
} |
465 |
|
if (ex != null) |
466 |
< |
rethrowException(ex); |
466 |
> |
UNSAFE.throwException(ex); |
467 |
|
return tasks; |
468 |
|
} |
469 |
|
|
470 |
|
/** |
471 |
< |
* Returns {@code true} if the computation performed by this task |
472 |
< |
* has completed (or has been cancelled). |
473 |
< |
* |
474 |
< |
* @return {@code true} if this computation has completed |
475 |
< |
*/ |
476 |
< |
public final boolean isDone() { |
477 |
< |
return status < 0; |
676 |
< |
} |
677 |
< |
|
678 |
< |
/** |
679 |
< |
* Returns {@code true} if this task was cancelled. |
680 |
< |
* |
681 |
< |
* @return {@code true} if this task was cancelled |
682 |
< |
*/ |
683 |
< |
public final boolean isCancelled() { |
684 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
685 |
< |
} |
686 |
< |
|
687 |
< |
/** |
688 |
< |
* Asserts that the results of this task's computation will not be |
689 |
< |
* used. If a cancellation occurs before attempting to execute this |
690 |
< |
* task, execution will be suppressed, {@link #isCancelled} |
691 |
< |
* will report true, and {@link #join} will result in a |
692 |
< |
* {@code CancellationException} being thrown. Otherwise, when |
693 |
< |
* cancellation races with completion, there are no guarantees |
694 |
< |
* about whether {@code isCancelled} will report {@code true}, |
695 |
< |
* whether {@code join} will return normally or via an exception, |
696 |
< |
* or whether these behaviors will remain consistent upon repeated |
697 |
< |
* invocation. |
471 |
> |
* Attempts to cancel execution of this task. This attempt will |
472 |
> |
* fail if the task has already completed, has already been |
473 |
> |
* cancelled, or could not be cancelled for some other reason. If |
474 |
> |
* successful, and this task has not started when cancel is |
475 |
> |
* called, execution of this task is suppressed, {@link |
476 |
> |
* #isCancelled} will report true, and {@link #join} will result |
477 |
> |
* in a {@code CancellationException} being thrown. |
478 |
|
* |
479 |
|
* <p>This method may be overridden in subclasses, but if so, must |
480 |
|
* still ensure that these minimal properties hold. In particular, |
486 |
|
* invoke {@link #completeExceptionally}. |
487 |
|
* |
488 |
|
* @param mayInterruptIfRunning this value is ignored in the |
489 |
< |
* default implementation because tasks are not in general |
489 |
> |
* default implementation because tasks are not |
490 |
|
* cancelled via interruption |
491 |
|
* |
492 |
|
* @return {@code true} if this task is now cancelled |
493 |
|
*/ |
494 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
495 |
|
setCompletion(CANCELLED); |
496 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
496 |
> |
return status == CANCELLED; |
497 |
> |
} |
498 |
> |
|
499 |
> |
/** |
500 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
501 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
502 |
> |
* exceptions, but if it does anyway, we have no recourse during |
503 |
> |
* shutdown, so guard against this case. |
504 |
> |
*/ |
505 |
> |
final void cancelIgnoringExceptions() { |
506 |
> |
try { |
507 |
> |
cancel(false); |
508 |
> |
} catch (Throwable ignore) { |
509 |
> |
} |
510 |
> |
} |
511 |
> |
|
512 |
> |
/** |
513 |
> |
* Cancels ignoring exceptions if worker is terminating |
514 |
> |
*/ |
515 |
> |
final void cancelIfTerminating() { |
516 |
> |
Thread t = Thread.currentThread(); |
517 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
518 |
> |
((ForkJoinWorkerThread) t).isTerminating()) { |
519 |
> |
try { |
520 |
> |
cancel(false); |
521 |
> |
} catch (Throwable ignore) { |
522 |
> |
} |
523 |
> |
} |
524 |
> |
} |
525 |
> |
|
526 |
> |
public final boolean isDone() { |
527 |
> |
return status < 0; |
528 |
> |
} |
529 |
> |
|
530 |
> |
public final boolean isCancelled() { |
531 |
> |
return status == CANCELLED; |
532 |
|
} |
533 |
|
|
534 |
|
/** |
537 |
|
* @return {@code true} if this task threw an exception or was cancelled |
538 |
|
*/ |
539 |
|
public final boolean isCompletedAbnormally() { |
540 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
540 |
> |
return status < NORMAL; |
541 |
> |
} |
542 |
> |
|
543 |
> |
/** |
544 |
> |
* Returns {@code true} if this task completed without throwing an |
545 |
> |
* exception and was not cancelled. |
546 |
> |
* |
547 |
> |
* @return {@code true} if this task completed without throwing an |
548 |
> |
* exception and was not cancelled |
549 |
> |
*/ |
550 |
> |
public final boolean isCompletedNormally() { |
551 |
> |
return status == NORMAL; |
552 |
|
} |
553 |
|
|
554 |
|
/** |
559 |
|
* @return the exception, or {@code null} if none |
560 |
|
*/ |
561 |
|
public final Throwable getException() { |
562 |
< |
int s = status & COMPLETION_MASK; |
563 |
< |
if (s >= NORMAL) |
564 |
< |
return null; |
565 |
< |
if (s == CANCELLED) |
740 |
< |
return new CancellationException(); |
741 |
< |
return exceptionMap.get(this); |
562 |
> |
int s = status; |
563 |
> |
return ((s >= NORMAL) ? null : |
564 |
> |
(s == CANCELLED) ? new CancellationException() : |
565 |
> |
exceptionMap.get(this)); |
566 |
|
} |
567 |
|
|
568 |
|
/** |
575 |
|
* overridable, but overridden versions must invoke {@code super} |
576 |
|
* implementation to maintain guarantees. |
577 |
|
* |
578 |
< |
* @param ex the exception to throw. If this exception is |
579 |
< |
* not a RuntimeException or Error, the actual exception thrown |
580 |
< |
* will be a RuntimeException with cause ex. |
578 |
> |
* @param ex the exception to throw. If this exception is not a |
579 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
580 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
581 |
|
*/ |
582 |
|
public void completeExceptionally(Throwable ex) { |
583 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
584 |
< |
(ex instanceof Error) ? ex : |
585 |
< |
new RuntimeException(ex)); |
583 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
584 |
> |
(ex instanceof Error) ? ex : |
585 |
> |
new RuntimeException(ex)); |
586 |
|
} |
587 |
|
|
588 |
|
/** |
601 |
|
try { |
602 |
|
setRawResult(value); |
603 |
|
} catch (Throwable rex) { |
604 |
< |
setDoneExceptionally(rex); |
604 |
> |
setExceptionalCompletion(rex); |
605 |
|
return; |
606 |
|
} |
607 |
< |
setNormalCompletion(); |
607 |
> |
setCompletion(NORMAL); |
608 |
|
} |
609 |
|
|
610 |
|
public final V get() throws InterruptedException, ExecutionException { |
611 |
< |
ForkJoinWorkerThread w = getWorker(); |
612 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
613 |
< |
awaitDone(w, true); |
614 |
< |
return reportFutureResult(); |
611 |
> |
quietlyJoin(); |
612 |
> |
if (Thread.interrupted()) |
613 |
> |
throw new InterruptedException(); |
614 |
> |
int s = status; |
615 |
> |
if (s < NORMAL) { |
616 |
> |
Throwable ex; |
617 |
> |
if (s == CANCELLED) |
618 |
> |
throw new CancellationException(); |
619 |
> |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
620 |
> |
throw new ExecutionException(ex); |
621 |
> |
} |
622 |
> |
return getRawResult(); |
623 |
|
} |
624 |
|
|
625 |
|
public final V get(long timeout, TimeUnit unit) |
626 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
627 |
< |
long nanos = unit.toNanos(timeout); |
628 |
< |
ForkJoinWorkerThread w = getWorker(); |
629 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
630 |
< |
awaitDone(w, nanos); |
631 |
< |
return reportTimedFutureResult(); |
632 |
< |
} |
633 |
< |
|
802 |
< |
/** |
803 |
< |
* Possibly executes other tasks until this task is ready, then |
804 |
< |
* returns the result of the computation. This method may be more |
805 |
< |
* efficient than {@code join}, but is only applicable when |
806 |
< |
* there are no potential dependencies between continuation of the |
807 |
< |
* current task and that of any other task that might be executed |
808 |
< |
* while helping. (This usually holds for pure divide-and-conquer |
809 |
< |
* tasks). This method may be invoked only from within |
810 |
< |
* ForkJoinTask computations (as may be determined using method |
811 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
812 |
< |
* result in exceptions or errors, possibly including |
813 |
< |
* ClassCastException. |
814 |
< |
* |
815 |
< |
* @return the computed result |
816 |
< |
*/ |
817 |
< |
public final V helpJoin() { |
818 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
819 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
820 |
< |
reportException(busyJoin(w)); |
821 |
< |
return getRawResult(); |
822 |
< |
} |
823 |
< |
|
824 |
< |
/** |
825 |
< |
* Possibly executes other tasks until this task is ready. This |
826 |
< |
* method may be invoked only from within ForkJoinTask |
827 |
< |
* computations (as may be determined using method {@link |
828 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
829 |
< |
* in exceptions or errors, possibly including ClassCastException. |
830 |
< |
*/ |
831 |
< |
public final void quietlyHelpJoin() { |
832 |
< |
if (status >= 0) { |
833 |
< |
ForkJoinWorkerThread w = |
834 |
< |
(ForkJoinWorkerThread) Thread.currentThread(); |
835 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
836 |
< |
busyJoin(w); |
627 |
> |
Thread t = Thread.currentThread(); |
628 |
> |
ForkJoinPool pool; |
629 |
> |
if (t instanceof ForkJoinWorkerThread) { |
630 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
631 |
> |
if (status >= 0 && w.unpushTask(this)) |
632 |
> |
quietlyExec(); |
633 |
> |
pool = w.pool; |
634 |
|
} |
635 |
+ |
else |
636 |
+ |
pool = null; |
637 |
+ |
/* |
638 |
+ |
* Timed wait loop intermixes cases for FJ (pool != null) and |
639 |
+ |
* non FJ threads. For FJ, decrement pool count but don't try |
640 |
+ |
* for replacement; increment count on completion. For non-FJ, |
641 |
+ |
* deal with interrupts. This is messy, but a little less so |
642 |
+ |
* than is splitting the FJ and nonFJ cases. |
643 |
+ |
*/ |
644 |
+ |
boolean interrupted = false; |
645 |
+ |
boolean dec = false; // true if pool count decremented |
646 |
+ |
for (;;) { |
647 |
+ |
if (Thread.interrupted() && pool == null) { |
648 |
+ |
interrupted = true; |
649 |
+ |
break; |
650 |
+ |
} |
651 |
+ |
int s = status; |
652 |
+ |
if (s < 0) |
653 |
+ |
break; |
654 |
+ |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) { |
655 |
+ |
long startTime = System.nanoTime(); |
656 |
+ |
long nanos = unit.toNanos(timeout); |
657 |
+ |
long nt; // wait time |
658 |
+ |
while (status >= 0 && |
659 |
+ |
(nt = nanos - (System.nanoTime() - startTime)) > 0) { |
660 |
+ |
if (pool != null && !dec) |
661 |
+ |
dec = pool.tryDecrementRunningCount(); |
662 |
+ |
else { |
663 |
+ |
long ms = nt / 1000000; |
664 |
+ |
int ns = (int) (nt % 1000000); |
665 |
+ |
try { |
666 |
+ |
synchronized(this) { |
667 |
+ |
if (status >= 0) |
668 |
+ |
wait(ms, ns); |
669 |
+ |
} |
670 |
+ |
} catch (InterruptedException ie) { |
671 |
+ |
if (pool != null) |
672 |
+ |
cancelIfTerminating(); |
673 |
+ |
else { |
674 |
+ |
interrupted = true; |
675 |
+ |
break; |
676 |
+ |
} |
677 |
+ |
} |
678 |
+ |
} |
679 |
+ |
} |
680 |
+ |
break; |
681 |
+ |
} |
682 |
+ |
} |
683 |
+ |
if (pool != null && dec) |
684 |
+ |
pool.incrementRunningCount(); |
685 |
+ |
if (interrupted) |
686 |
+ |
throw new InterruptedException(); |
687 |
+ |
int es = status; |
688 |
+ |
if (es != NORMAL) { |
689 |
+ |
Throwable ex; |
690 |
+ |
if (es == CANCELLED) |
691 |
+ |
throw new CancellationException(); |
692 |
+ |
if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
693 |
+ |
throw new ExecutionException(ex); |
694 |
+ |
throw new TimeoutException(); |
695 |
+ |
} |
696 |
+ |
return getRawResult(); |
697 |
|
} |
698 |
|
|
699 |
|
/** |
700 |
< |
* Joins this task, without returning its result or throwing an |
700 |
> |
* Joins this task, without returning its result or throwing its |
701 |
|
* exception. This method may be useful when processing |
702 |
|
* collections of tasks when some have been cancelled or otherwise |
703 |
|
* known to have aborted. |
704 |
|
*/ |
705 |
|
public final void quietlyJoin() { |
706 |
< |
if (status >= 0) { |
707 |
< |
ForkJoinWorkerThread w = getWorker(); |
708 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
709 |
< |
awaitDone(w, true); |
706 |
> |
Thread t; |
707 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
708 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
709 |
> |
if (status >= 0) { |
710 |
> |
if (w.unpushTask(this)) { |
711 |
> |
boolean completed; |
712 |
> |
try { |
713 |
> |
completed = exec(); |
714 |
> |
} catch (Throwable rex) { |
715 |
> |
setExceptionalCompletion(rex); |
716 |
> |
return; |
717 |
> |
} |
718 |
> |
if (completed) { |
719 |
> |
setCompletion(NORMAL); |
720 |
> |
return; |
721 |
> |
} |
722 |
> |
} |
723 |
> |
w.joinTask(this); |
724 |
> |
} |
725 |
|
} |
726 |
+ |
else |
727 |
+ |
externalAwaitDone(); |
728 |
|
} |
729 |
|
|
730 |
|
/** |
731 |
|
* Commences performing this task and awaits its completion if |
732 |
< |
* necessary, without returning its result or throwing an |
732 |
> |
* necessary, without returning its result or throwing its |
733 |
|
* exception. This method may be useful when processing |
734 |
|
* collections of tasks when some have been cancelled or otherwise |
735 |
|
* known to have aborted. |
736 |
|
*/ |
737 |
|
public final void quietlyInvoke() { |
738 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
739 |
< |
quietlyJoin(); |
738 |
> |
if (status >= 0) { |
739 |
> |
boolean completed; |
740 |
> |
try { |
741 |
> |
completed = exec(); |
742 |
> |
} catch (Throwable rex) { |
743 |
> |
setExceptionalCompletion(rex); |
744 |
> |
return; |
745 |
> |
} |
746 |
> |
if (completed) |
747 |
> |
setCompletion(NORMAL); |
748 |
> |
else |
749 |
> |
quietlyJoin(); |
750 |
> |
} |
751 |
|
} |
752 |
|
|
753 |
|
/** |
754 |
|
* Possibly executes tasks until the pool hosting the current task |
755 |
< |
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
756 |
< |
* designs in which many tasks are forked, but none are explicitly |
757 |
< |
* joined, instead executing them until all are processed. This |
758 |
< |
* method may be invoked only from within ForkJoinTask |
759 |
< |
* computations (as may be determined using method {@link |
760 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
761 |
< |
* in exceptions or errors, possibly including ClassCastException. |
755 |
> |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
756 |
> |
* be of use in designs in which many tasks are forked, but none |
757 |
> |
* are explicitly joined, instead executing them until all are |
758 |
> |
* processed. |
759 |
> |
* |
760 |
> |
* <p>This method may be invoked only from within {@code |
761 |
> |
* ForkJoinTask} computations (as may be determined using method |
762 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
763 |
> |
* result in exceptions or errors, possibly including {@code |
764 |
> |
* ClassCastException}. |
765 |
|
*/ |
766 |
|
public static void helpQuiesce() { |
767 |
|
((ForkJoinWorkerThread) Thread.currentThread()) |
774 |
|
* this task, but only if reuse occurs when this task has either |
775 |
|
* never been forked, or has been forked, then completed and all |
776 |
|
* outstanding joins of this task have also completed. Effects |
777 |
< |
* under any other usage conditions are not guaranteed, and are |
778 |
< |
* discouraged. This method may be useful when executing |
777 |
> |
* under any other usage conditions are not guaranteed. |
778 |
> |
* This method may be useful when executing |
779 |
|
* pre-constructed trees of subtasks in loops. |
780 |
|
*/ |
781 |
|
public void reinitialize() { |
782 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
782 |
> |
if (status == EXCEPTIONAL) |
783 |
|
exceptionMap.remove(this); |
784 |
|
status = 0; |
785 |
|
} |
814 |
|
* by the current thread, and has not commenced executing in |
815 |
|
* another thread. This method may be useful when arranging |
816 |
|
* alternative local processing of tasks that could have been, but |
817 |
< |
* were not, stolen. This method may be invoked only from within |
818 |
< |
* ForkJoinTask computations (as may be determined using method |
819 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
820 |
< |
* result in exceptions or errors, possibly including |
821 |
< |
* ClassCastException. |
817 |
> |
* were not, stolen. |
818 |
> |
* |
819 |
> |
* <p>This method may be invoked only from within {@code |
820 |
> |
* ForkJoinTask} computations (as may be determined using method |
821 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
822 |
> |
* result in exceptions or errors, possibly including {@code |
823 |
> |
* ClassCastException}. |
824 |
|
* |
825 |
|
* @return {@code true} if unforked |
826 |
|
*/ |
833 |
|
* Returns an estimate of the number of tasks that have been |
834 |
|
* forked by the current worker thread but not yet executed. This |
835 |
|
* value may be useful for heuristic decisions about whether to |
836 |
< |
* fork other tasks. This method may be invoked only from within |
837 |
< |
* ForkJoinTask computations (as may be determined using method |
838 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
839 |
< |
* result in exceptions or errors, possibly including |
840 |
< |
* ClassCastException. |
836 |
> |
* fork other tasks. |
837 |
> |
* |
838 |
> |
* <p>This method may be invoked only from within {@code |
839 |
> |
* ForkJoinTask} computations (as may be determined using method |
840 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
841 |
> |
* result in exceptions or errors, possibly including {@code |
842 |
> |
* ClassCastException}. |
843 |
> |
* |
844 |
|
* @return the number of tasks |
845 |
|
*/ |
846 |
|
public static int getQueuedTaskCount() { |
856 |
|
* usages of ForkJoinTasks, at steady state, each worker should |
857 |
|
* aim to maintain a small constant surplus (for example, 3) of |
858 |
|
* tasks, and to process computations locally if this threshold is |
859 |
< |
* exceeded. This method may be invoked only from within |
860 |
< |
* ForkJoinTask computations (as may be determined using method |
861 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
862 |
< |
* result in exceptions or errors, possibly including |
863 |
< |
* ClassCastException. * |
859 |
> |
* exceeded. |
860 |
> |
* |
861 |
> |
* <p>This method may be invoked only from within {@code |
862 |
> |
* ForkJoinTask} computations (as may be determined using method |
863 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
864 |
> |
* result in exceptions or errors, possibly including {@code |
865 |
> |
* ClassCastException}. |
866 |
> |
* |
867 |
|
* @return the surplus number of tasks, which may be negative |
868 |
|
*/ |
869 |
|
public static int getSurplusQueuedTaskCount() { |
899 |
|
* called otherwise. The return value controls whether this task |
900 |
|
* is considered to be done normally. It may return false in |
901 |
|
* asynchronous actions that require explicit invocations of |
902 |
< |
* {@link #complete} to become joinable. It may throw exceptions |
903 |
< |
* to indicate abnormal exit. |
902 |
> |
* {@link #complete} to become joinable. It may also throw an |
903 |
> |
* (unchecked) exception to indicate abnormal exit. |
904 |
|
* |
905 |
|
* @return {@code true} if completed normally |
1008 |
– |
* @throws Error or RuntimeException if encountered during computation |
906 |
|
*/ |
907 |
|
protected abstract boolean exec(); |
908 |
|
|
914 |
|
* null even if a task exists but cannot be accessed without |
915 |
|
* contention with other threads. This method is designed |
916 |
|
* primarily to support extensions, and is unlikely to be useful |
917 |
< |
* otherwise. This method may be invoked only from within |
918 |
< |
* ForkJoinTask computations (as may be determined using method |
919 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
920 |
< |
* result in exceptions or errors, possibly including |
921 |
< |
* ClassCastException. |
917 |
> |
* otherwise. |
918 |
> |
* |
919 |
> |
* <p>This method may be invoked only from within {@code |
920 |
> |
* ForkJoinTask} computations (as may be determined using method |
921 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
922 |
> |
* result in exceptions or errors, possibly including {@code |
923 |
> |
* ClassCastException}. |
924 |
|
* |
925 |
|
* @return the next task, or {@code null} if none are available |
926 |
|
*/ |
933 |
|
* Unschedules and returns, without executing, the next task |
934 |
|
* queued by the current thread but not yet executed. This method |
935 |
|
* is designed primarily to support extensions, and is unlikely to |
936 |
< |
* be useful otherwise. This method may be invoked only from |
937 |
< |
* within ForkJoinTask computations (as may be determined using |
938 |
< |
* method {@link #inForkJoinPool}). Attempts to invoke in other |
939 |
< |
* contexts result in exceptions or errors, possibly including |
940 |
< |
* ClassCastException. |
936 |
> |
* be useful otherwise. |
937 |
> |
* |
938 |
> |
* <p>This method may be invoked only from within {@code |
939 |
> |
* ForkJoinTask} computations (as may be determined using method |
940 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
941 |
> |
* result in exceptions or errors, possibly including {@code |
942 |
> |
* ClassCastException}. |
943 |
|
* |
944 |
|
* @return the next task, or {@code null} if none are available |
945 |
|
*/ |
956 |
|
* {@code null} result does not necessarily imply quiescence |
957 |
|
* of the pool this task is operating in. This method is designed |
958 |
|
* primarily to support extensions, and is unlikely to be useful |
959 |
< |
* otherwise. This method may be invoked only from within |
960 |
< |
* ForkJoinTask computations (as may be determined using method |
961 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
962 |
< |
* result in exceptions or errors, possibly including |
963 |
< |
* ClassCastException. |
959 |
> |
* otherwise. |
960 |
> |
* |
961 |
> |
* <p>This method may be invoked only from within {@code |
962 |
> |
* ForkJoinTask} computations (as may be determined using method |
963 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
964 |
> |
* result in exceptions or errors, possibly including {@code |
965 |
> |
* ClassCastException}. |
966 |
|
* |
967 |
|
* @return a task, or {@code null} if none are available |
968 |
|
*/ |
1027 |
|
} |
1028 |
|
|
1029 |
|
/** |
1030 |
< |
* Returns a new ForkJoinTask that performs the {@code run} |
1031 |
< |
* method of the given Runnable as its action, and returns a null |
1032 |
< |
* result upon {@code join}. |
1030 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1031 |
> |
* method of the given {@code Runnable} as its action, and returns |
1032 |
> |
* a null result upon {@link #join}. |
1033 |
|
* |
1034 |
|
* @param runnable the runnable action |
1035 |
|
* @return the task |
1039 |
|
} |
1040 |
|
|
1041 |
|
/** |
1042 |
< |
* Returns a new ForkJoinTask that performs the {@code run} |
1043 |
< |
* method of the given Runnable as its action, and returns the |
1044 |
< |
* given result upon {@code join}. |
1042 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1043 |
> |
* method of the given {@code Runnable} as its action, and returns |
1044 |
> |
* the given result upon {@link #join}. |
1045 |
|
* |
1046 |
|
* @param runnable the runnable action |
1047 |
|
* @param result the result upon completion |
1052 |
|
} |
1053 |
|
|
1054 |
|
/** |
1055 |
< |
* Returns a new ForkJoinTask that performs the {@code call} |
1056 |
< |
* method of the given Callable as its action, and returns its |
1057 |
< |
* result upon {@code join}, translating any checked |
1058 |
< |
* exceptions encountered into {@code RuntimeException}. |
1055 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1056 |
> |
* method of the given {@code Callable} as its action, and returns |
1057 |
> |
* its result upon {@link #join}, translating any checked exceptions |
1058 |
> |
* encountered into {@code RuntimeException}. |
1059 |
|
* |
1060 |
|
* @param callable the callable action |
1061 |
|
* @return the task |
1069 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1070 |
|
|
1071 |
|
/** |
1072 |
< |
* Save the state to a stream. |
1072 |
> |
* Saves the state to a stream. |
1073 |
|
* |
1074 |
|
* @serialData the current run status and the exception thrown |
1075 |
|
* during execution, or {@code null} if none |
1082 |
|
} |
1083 |
|
|
1084 |
|
/** |
1085 |
< |
* Reconstitute the instance from a stream. |
1085 |
> |
* Reconstitutes the instance from a stream. |
1086 |
|
* |
1087 |
|
* @param s the stream |
1088 |
|
*/ |
1089 |
|
private void readObject(java.io.ObjectInputStream s) |
1090 |
|
throws java.io.IOException, ClassNotFoundException { |
1091 |
|
s.defaultReadObject(); |
1189 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1190 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1092 |
|
Object ex = s.readObject(); |
1093 |
|
if (ex != null) |
1094 |
< |
setDoneExceptionally((Throwable) ex); |
1094 |
> |
setExceptionalCompletion((Throwable) ex); |
1095 |
|
} |
1096 |
|
|
1097 |
|
// Unsafe mechanics |