5 |
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*/ |
6 |
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|
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package jsr166y; |
8 |
< |
import java.io.Serializable; |
9 |
< |
import java.util.*; |
8 |
> |
|
9 |
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import java.util.concurrent.*; |
10 |
< |
import java.util.concurrent.atomic.*; |
11 |
< |
import sun.misc.Unsafe; |
12 |
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import java.lang.reflect.*; |
10 |
> |
|
11 |
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import java.io.Serializable; |
12 |
> |
import java.util.Collection; |
13 |
> |
import java.util.Collections; |
14 |
> |
import java.util.List; |
15 |
> |
import java.util.Map; |
16 |
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import java.util.WeakHashMap; |
17 |
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|
18 |
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/** |
19 |
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* Abstract base class for tasks that run within a {@link |
20 |
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* ForkJoinPool}. A ForkJoinTask is a thread-like entity that is much |
19 |
> |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
20 |
> |
* A {@code ForkJoinTask} is a thread-like entity that is much |
21 |
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* lighter weight than a normal thread. Huge numbers of tasks and |
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* subtasks may be hosted by a small number of actual threads in a |
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* ForkJoinPool, at the price of some usage limitations. |
24 |
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* |
25 |
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* <p> A "main" ForkJoinTask begins execution when submitted to a |
26 |
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* {@link ForkJoinPool}. Once started, it will usually in turn start |
27 |
< |
* other subtasks. As indicated by the name of this class, many |
28 |
< |
* programs using ForkJoinTasks employ only methods {@code fork} |
29 |
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* and {@code join}, or derivatives such as |
30 |
< |
* {@code invokeAll}. However, this class also provides a number |
31 |
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* of other methods that can come into play in advanced usages, as |
32 |
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* well as extension mechanics that allow support of new forms of |
33 |
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* fork/join processing. |
25 |
> |
* <p>A "main" {@code ForkJoinTask} begins execution when submitted |
26 |
> |
* to a {@link ForkJoinPool}. Once started, it will usually in turn |
27 |
> |
* start other subtasks. As indicated by the name of this class, |
28 |
> |
* many programs using {@code ForkJoinTask} employ only methods |
29 |
> |
* {@link #fork} and {@link #join}, or derivatives such as {@link |
30 |
> |
* #invokeAll}. However, this class also provides a number of other |
31 |
> |
* methods that can come into play in advanced usages, as well as |
32 |
> |
* extension mechanics that allow support of new forms of fork/join |
33 |
> |
* processing. |
34 |
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* |
35 |
< |
* <p>A ForkJoinTask is a lightweight form of {@link Future}. The |
36 |
< |
* efficiency of ForkJoinTasks stems from a set of restrictions (that |
37 |
< |
* are only partially statically enforceable) reflecting their |
38 |
< |
* intended use as computational tasks calculating pure functions or |
39 |
< |
* operating on purely isolated objects. The primary coordination |
40 |
< |
* mechanisms are {@link #fork}, that arranges asynchronous execution, |
41 |
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* and {@link #join}, that doesn't proceed until the task's result has |
42 |
< |
* been computed. Computations should avoid {@code synchronized} |
43 |
< |
* methods or blocks, and should minimize other blocking |
44 |
< |
* synchronization apart from joining other tasks or using |
45 |
< |
* synchronizers such as Phasers that are advertised to cooperate with |
46 |
< |
* fork/join scheduling. Tasks should also not perform blocking IO, |
47 |
< |
* and should ideally access variables that are completely independent |
48 |
< |
* of those accessed by other running tasks. Minor breaches of these |
49 |
< |
* restrictions, for example using shared output streams, may be |
50 |
< |
* tolerable in practice, but frequent use may result in poor |
51 |
< |
* performance, and the potential to indefinitely stall if the number |
52 |
< |
* of threads not waiting for IO or other external synchronization |
53 |
< |
* becomes exhausted. This usage restriction is in part enforced by |
54 |
< |
* not permitting checked exceptions such as {@code IOExceptions} |
55 |
< |
* to be thrown. However, computations may still encounter unchecked |
56 |
< |
* exceptions, that are rethrown to callers attempting join |
57 |
< |
* them. These exceptions may additionally include |
58 |
< |
* RejectedExecutionExceptions stemming from internal resource |
59 |
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* exhaustion such as failure to allocate internal task queues. |
35 |
> |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
36 |
> |
* The efficiency of {@code ForkJoinTask}s stems from a set of |
37 |
> |
* restrictions (that are only partially statically enforceable) |
38 |
> |
* reflecting their intended use as computational tasks calculating |
39 |
> |
* pure functions or operating on purely isolated objects. The |
40 |
> |
* primary coordination mechanisms are {@link #fork}, that arranges |
41 |
> |
* asynchronous execution, and {@link #join}, that doesn't proceed |
42 |
> |
* until the task's result has been computed. Computations should |
43 |
> |
* avoid {@code synchronized} methods or blocks, and should minimize |
44 |
> |
* other blocking synchronization apart from joining other tasks or |
45 |
> |
* using synchronizers such as Phasers that are advertised to |
46 |
> |
* cooperate with fork/join scheduling. Tasks should also not perform |
47 |
> |
* blocking IO, and should ideally access variables that are |
48 |
> |
* completely independent of those accessed by other running |
49 |
> |
* tasks. Minor breaches of these restrictions, for example using |
50 |
> |
* shared output streams, may be tolerable in practice, but frequent |
51 |
> |
* use may result in poor performance, and the potential to |
52 |
> |
* indefinitely stall if the number of threads not waiting for IO or |
53 |
> |
* other external synchronization becomes exhausted. This usage |
54 |
> |
* restriction is in part enforced by not permitting checked |
55 |
> |
* exceptions such as {@code IOExceptions} to be thrown. However, |
56 |
> |
* computations may still encounter unchecked exceptions, that are |
57 |
> |
* rethrown to callers attempting join them. These exceptions may |
58 |
> |
* additionally include RejectedExecutionExceptions stemming from |
59 |
> |
* internal resource exhaustion such as failure to allocate internal |
60 |
> |
* task queues. |
61 |
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* |
62 |
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* <p>The primary method for awaiting completion and extracting |
63 |
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* results of a task is {@link #join}, but there are several variants: |
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* performs the most common form of parallel invocation: forking a set |
77 |
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* of tasks and joining them all. |
78 |
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* |
79 |
< |
* <p> The ForkJoinTask class is not usually directly subclassed. |
79 |
> |
* <p>The ForkJoinTask class is not usually directly subclassed. |
80 |
|
* Instead, you subclass one of the abstract classes that support a |
81 |
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* particular style of fork/join processing. Normally, a concrete |
81 |
> |
* particular style of fork/join processing, typically {@link |
82 |
> |
* RecursiveAction} for computations that do not return results, or |
83 |
> |
* {@link RecursiveTask} for those that do. Normally, a concrete |
84 |
|
* ForkJoinTask subclass declares fields comprising its parameters, |
85 |
|
* established in a constructor, and then defines a {@code compute} |
86 |
|
* method that somehow uses the control methods supplied by this base |
87 |
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* class. While these methods have {@code public} access (to allow |
88 |
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* instances of different task subclasses to call each others |
89 |
|
* methods), some of them may only be called from within other |
90 |
< |
* ForkJoinTasks. Attempts to invoke them in other contexts result in |
91 |
< |
* exceptions or errors possibly including ClassCastException. |
90 |
> |
* ForkJoinTasks (as may be determined using method {@link |
91 |
> |
* #inForkJoinPool}). Attempts to invoke them in other contexts |
92 |
> |
* result in exceptions or errors, possibly including |
93 |
> |
* ClassCastException. |
94 |
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* |
95 |
|
* <p>Most base support methods are {@code final} because their |
96 |
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* implementations are intrinsically tied to the underlying |
97 |
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* lightweight task scheduling framework, and so cannot be overridden. |
98 |
|
* Developers creating new basic styles of fork/join processing should |
99 |
|
* minimally implement {@code protected} methods |
100 |
< |
* {@code exec}, {@code setRawResult}, and |
101 |
< |
* {@code getRawResult}, while also introducing an abstract |
100 |
> |
* {@link #exec}, {@link #setRawResult}, and |
101 |
> |
* {@link #getRawResult}, while also introducing an abstract |
102 |
|
* computational method that can be implemented in its subclasses, |
103 |
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* possibly relying on other {@code protected} methods provided |
104 |
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* by this class. |
105 |
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* |
106 |
|
* <p>ForkJoinTasks should perform relatively small amounts of |
107 |
< |
* computations, othewise splitting into smaller tasks. As a very |
107 |
> |
* computations, otherwise splitting into smaller tasks. As a very |
108 |
|
* rough rule of thumb, a task should perform more than 100 and less |
109 |
|
* than 10000 basic computational steps. If tasks are too big, then |
110 |
< |
* parellelism cannot improve throughput. If too small, then memory |
110 |
> |
* parallelism cannot improve throughput. If too small, then memory |
111 |
|
* and internal task maintenance overhead may overwhelm processing. |
112 |
|
* |
113 |
+ |
* <p>This class provides {@code adapt} methods for {@link |
114 |
+ |
* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that |
115 |
+ |
* may be of use when mixing execution of ForkJoinTasks with other |
116 |
+ |
* kinds of tasks. When all tasks are of this form, consider using a |
117 |
+ |
* pool in {@link ForkJoinPool#setAsyncMode}. |
118 |
+ |
* |
119 |
|
* <p>ForkJoinTasks are {@code Serializable}, which enables them |
120 |
|
* to be used in extensions such as remote execution frameworks. It is |
121 |
|
* in general sensible to serialize tasks only before or after, but |
122 |
|
* not during execution. Serialization is not relied on during |
123 |
|
* execution itself. |
124 |
+ |
* |
125 |
+ |
* @since 1.7 |
126 |
+ |
* @author Doug Lea |
127 |
|
*/ |
128 |
|
public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
129 |
|
|
145 |
|
* currently unused. Also value 0x80000000 is available as spare |
146 |
|
* completion value. |
147 |
|
*/ |
148 |
< |
volatile int status; // accessed directy by pool and workers |
148 |
> |
volatile int status; // accessed directly by pool and workers |
149 |
|
|
150 |
|
static final int COMPLETION_MASK = 0xe0000000; |
151 |
|
static final int NORMAL = 0xe0000000; // == mask |
158 |
|
/** |
159 |
|
* Table of exceptions thrown by tasks, to enable reporting by |
160 |
|
* callers. Because exceptions are rare, we don't directly keep |
161 |
< |
* them with task objects, but instead us a weak ref table. Note |
161 |
> |
* them with task objects, but instead use a weak ref table. Note |
162 |
|
* that cancellation exceptions don't appear in the table, but are |
163 |
|
* instead recorded as status values. |
164 |
< |
* Todo: Use ConcurrentReferenceHashMap |
164 |
> |
* TODO: Use ConcurrentReferenceHashMap |
165 |
|
*/ |
166 |
|
static final Map<ForkJoinTask<?>, Throwable> exceptionMap = |
167 |
|
Collections.synchronizedMap |
170 |
|
// within-package utilities |
171 |
|
|
172 |
|
/** |
173 |
< |
* Get current worker thread, or null if not a worker thread |
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); |
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); |
182 |
> |
return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val); |
183 |
|
} |
184 |
|
|
185 |
|
/** |
187 |
|
*/ |
188 |
|
static void rethrowException(Throwable ex) { |
189 |
|
if (ex != null) |
190 |
< |
_unsafe.throwException(ex); |
190 |
> |
UNSAFE.throwException(ex); |
191 |
|
} |
192 |
|
|
193 |
|
// Setting completion status |
194 |
|
|
195 |
|
/** |
196 |
< |
* Mark completion and wake up threads waiting to join this task. |
196 |
> |
* Marks completion and wakes up threads waiting to join this task. |
197 |
> |
* |
198 |
|
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
199 |
|
*/ |
200 |
|
final void setCompletion(int completion) { |
201 |
|
ForkJoinPool pool = getPool(); |
202 |
|
if (pool != null) { |
203 |
|
int s; // Clear signal bits while setting completion status |
204 |
< |
do;while ((s = status) >= 0 && !casStatus(s, completion)); |
204 |
> |
do {} while ((s = status) >= 0 && !casStatus(s, completion)); |
205 |
|
|
206 |
|
if ((s & SIGNAL_MASK) != 0) { |
207 |
|
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
208 |
|
pool.updateRunningCount(s); |
209 |
< |
synchronized(this) { notifyAll(); } |
209 |
> |
synchronized (this) { notifyAll(); } |
210 |
|
} |
211 |
|
} |
212 |
|
else |
219 |
|
*/ |
220 |
|
private void externallySetCompletion(int completion) { |
221 |
|
int s; |
222 |
< |
do;while ((s = status) >= 0 && |
223 |
< |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
224 |
< |
synchronized(this) { notifyAll(); } |
222 |
> |
do {} while ((s = status) >= 0 && |
223 |
> |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
224 |
> |
synchronized (this) { notifyAll(); } |
225 |
|
} |
226 |
|
|
227 |
|
/** |
228 |
< |
* Sets status to indicate normal completion |
228 |
> |
* Sets status to indicate normal completion. |
229 |
|
*/ |
230 |
|
final void setNormalCompletion() { |
231 |
|
// Try typical fast case -- single CAS, no signal, not already done. |
232 |
|
// Manually expand casStatus to improve chances of inlining it |
233 |
< |
if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
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 |
240 |
> |
* Performs the actual monitor wait for awaitDone. |
241 |
|
*/ |
242 |
|
private void doAwaitDone() { |
243 |
|
// Minimize lock bias and in/de-flation effects by maximizing |
244 |
|
// chances of waiting inside sync |
245 |
|
try { |
246 |
|
while (status >= 0) |
247 |
< |
synchronized(this) { if (status >= 0) wait(); } |
247 |
> |
synchronized (this) { if (status >= 0) wait(); } |
248 |
|
} catch (InterruptedException ie) { |
249 |
|
onInterruptedWait(); |
250 |
|
} |
251 |
|
} |
252 |
|
|
253 |
|
/** |
254 |
< |
* Performs the actual monitor wait for awaitDone |
254 |
> |
* Performs the actual timed monitor wait for awaitDone. |
255 |
|
*/ |
256 |
|
private void doAwaitDone(long startTime, long nanos) { |
257 |
< |
synchronized(this) { |
257 |
> |
synchronized (this) { |
258 |
|
try { |
259 |
|
while (status >= 0) { |
260 |
< |
long nt = nanos - System.nanoTime() - startTime; |
260 |
> |
long nt = nanos - (System.nanoTime() - startTime); |
261 |
|
if (nt <= 0) |
262 |
|
break; |
263 |
< |
wait(nt / 1000000, (int)(nt % 1000000)); |
263 |
> |
wait(nt / 1000000, (int) (nt % 1000000)); |
264 |
|
} |
265 |
|
} catch (InterruptedException ie) { |
266 |
|
onInterruptedWait(); |
273 |
|
/** |
274 |
|
* Sets status to indicate there is joiner, then waits for join, |
275 |
|
* surrounded with pool notifications. |
276 |
+ |
* |
277 |
|
* @return status upon exit |
278 |
|
*/ |
279 |
< |
private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) { |
280 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
279 |
> |
private int awaitDone(ForkJoinWorkerThread w, |
280 |
> |
boolean maintainParallelism) { |
281 |
> |
ForkJoinPool pool = (w == null) ? null : w.pool; |
282 |
|
int s; |
283 |
|
while ((s = status) >= 0) { |
284 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
284 |
> |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
285 |
|
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
286 |
|
doAwaitDone(); |
287 |
|
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
294 |
|
|
295 |
|
/** |
296 |
|
* Timed version of awaitDone |
297 |
+ |
* |
298 |
|
* @return status upon exit |
299 |
|
*/ |
300 |
|
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
301 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
301 |
> |
ForkJoinPool pool = (w == null) ? null : w.pool; |
302 |
|
int s; |
303 |
|
while ((s = status) >= 0) { |
304 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
304 |
> |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
305 |
|
long startTime = System.nanoTime(); |
306 |
|
if (pool == null || !pool.preJoin(this, false)) |
307 |
|
doAwaitDone(startTime, nanos); |
318 |
|
} |
319 |
|
|
320 |
|
/** |
321 |
< |
* Notify pool that thread is unblocked. Called by signalled |
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)); |
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 |
< |
* Notify pool to adjust counts on cancelled or timed out wait |
332 |
> |
* Notifies pool to adjust counts on cancelled or timed out wait. |
333 |
|
*/ |
334 |
|
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
335 |
|
if (pool != null) { |
344 |
|
} |
345 |
|
|
346 |
|
/** |
347 |
< |
* Handle interruptions during waits. |
347 |
> |
* Handles interruptions during waits. |
348 |
|
*/ |
349 |
|
private void onInterruptedWait() { |
350 |
|
ForkJoinWorkerThread w = getWorker(); |
363 |
|
} |
364 |
|
|
365 |
|
/** |
366 |
< |
* Throws the exception associated with status s; |
366 |
> |
* Throws the exception associated with status s. |
367 |
> |
* |
368 |
|
* @throws the exception |
369 |
|
*/ |
370 |
|
private void reportException(int s) { |
377 |
|
} |
378 |
|
|
379 |
|
/** |
380 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
381 |
< |
* Only call when isDone known to be true. |
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 { |
397 |
|
|
398 |
|
/** |
399 |
|
* Returns result or throws exception using j.u.c.Future conventions |
400 |
< |
* with timeouts |
400 |
> |
* with timeouts. |
401 |
|
*/ |
402 |
|
private V reportTimedFutureResult() |
403 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
418 |
|
|
419 |
|
/** |
420 |
|
* Calls exec, recording completion, and rethrowing exception if |
421 |
< |
* encountered. Caller should normally check status before calling |
421 |
> |
* encountered. Caller should normally check status before calling. |
422 |
> |
* |
423 |
|
* @return true if completed normally |
424 |
|
*/ |
425 |
|
private boolean tryExec() { |
437 |
|
|
438 |
|
/** |
439 |
|
* Main execution method used by worker threads. Invokes |
440 |
< |
* base computation unless already complete |
440 |
> |
* base computation unless already complete. |
441 |
|
*/ |
442 |
|
final void quietlyExec() { |
443 |
|
if (status >= 0) { |
444 |
|
try { |
445 |
|
if (!exec()) |
446 |
|
return; |
447 |
< |
} catch(Throwable rex) { |
447 |
> |
} catch (Throwable rex) { |
448 |
|
setDoneExceptionally(rex); |
449 |
|
return; |
450 |
|
} |
453 |
|
} |
454 |
|
|
455 |
|
/** |
456 |
< |
* Calls exec, recording but not rethrowing exception |
457 |
< |
* Caller should normally check status before calling |
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() { |
471 |
|
} |
472 |
|
|
473 |
|
/** |
474 |
< |
* Cancel, ignoring any exceptions it throws |
474 |
> |
* Cancels, ignoring any exceptions it throws. |
475 |
|
*/ |
476 |
|
final void cancelIgnoringExceptions() { |
477 |
|
try { |
478 |
|
cancel(false); |
479 |
< |
} catch(Throwable ignore) { |
479 |
> |
} catch (Throwable ignore) { |
480 |
|
} |
481 |
|
} |
482 |
|
|
488 |
|
ForkJoinTask<?> t; |
489 |
|
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
490 |
|
t.quietlyExec(); |
491 |
< |
return (s >= 0)? awaitDone(w, false) : s; // block if no work |
491 |
> |
return (s >= 0) ? awaitDone(w, false) : s; // block if no work |
492 |
|
} |
493 |
|
|
494 |
|
// public methods |
498 |
|
* necessarily enforced, it is a usage error to fork a task more |
499 |
|
* than once unless it has completed and been reinitialized. This |
500 |
|
* method may be invoked only from within ForkJoinTask |
501 |
< |
* computations. Attempts to invoke in other contexts result in |
502 |
< |
* exceptions or errors possibly including ClassCastException. |
501 |
> |
* computations (as may be determined using method {@link |
502 |
> |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
503 |
> |
* in exceptions or errors, possibly including ClassCastException. |
504 |
> |
* |
505 |
> |
* @return {@code this}, to simplify usage. |
506 |
|
*/ |
507 |
< |
public final void fork() { |
508 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this); |
507 |
> |
public final ForkJoinTask<V> fork() { |
508 |
> |
((ForkJoinWorkerThread) Thread.currentThread()) |
509 |
> |
.pushTask(this); |
510 |
> |
return this; |
511 |
|
} |
512 |
|
|
513 |
|
/** |
528 |
|
/** |
529 |
|
* Commences performing this task, awaits its completion if |
530 |
|
* necessary, and return its result. |
531 |
+ |
* |
532 |
|
* @throws Throwable (a RuntimeException, Error, or unchecked |
533 |
< |
* exception) if the underlying computation did so. |
533 |
> |
* exception) if the underlying computation did so |
534 |
|
* @return the computed result |
535 |
|
*/ |
536 |
|
public final V invoke() { |
541 |
|
} |
542 |
|
|
543 |
|
/** |
544 |
< |
* Forks both tasks, returning when {@code isDone} holds for |
545 |
< |
* both of them or an exception is encountered. This method may be |
546 |
< |
* invoked only from within ForkJoinTask computations. Attempts to |
547 |
< |
* invoke in other contexts result in exceptions or errors |
544 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
545 |
> |
* each task or an exception is encountered. This method may be |
546 |
> |
* invoked only from within ForkJoinTask computations (as may be |
547 |
> |
* determined using method {@link #inForkJoinPool}). Attempts to |
548 |
> |
* invoke in other contexts result in exceptions or errors, |
549 |
|
* possibly including ClassCastException. |
550 |
< |
* @param t1 one task |
551 |
< |
* @param t2 the other task |
552 |
< |
* @throws NullPointerException if t1 or t2 are null |
553 |
< |
* @throws RuntimeException or Error if either task did so. |
550 |
> |
* |
551 |
> |
* @param t1 the first task |
552 |
> |
* @param t2 the second task |
553 |
> |
* @throws NullPointerException if any task is null |
554 |
> |
* @throws RuntimeException or Error if a task did so |
555 |
|
*/ |
556 |
|
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
557 |
|
t2.fork(); |
560 |
|
} |
561 |
|
|
562 |
|
/** |
563 |
< |
* Forks the given tasks, returning when {@code isDone} holds |
564 |
< |
* for all of them. If any task encounters an exception, others |
565 |
< |
* may be cancelled. This method may be invoked only from within |
566 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
567 |
< |
* result in exceptions or errors possibly including ClassCastException. |
568 |
< |
* @param tasks the array of tasks |
569 |
< |
* @throws NullPointerException if tasks or any element are null. |
570 |
< |
* @throws RuntimeException or Error if any task did so. |
563 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
564 |
> |
* each task or an exception is encountered. If any task |
565 |
> |
* encounters an exception, others may be, but are not guaranteed |
566 |
> |
* to be, cancelled. This method may be invoked only from within |
567 |
> |
* ForkJoinTask computations (as may be determined using method |
568 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
569 |
> |
* result in exceptions or errors, possibly including |
570 |
> |
* ClassCastException. |
571 |
> |
* |
572 |
> |
* Overloadings of this method exist for the special cases |
573 |
> |
* of one to four arguments. |
574 |
> |
* |
575 |
> |
* @param tasks the tasks |
576 |
> |
* @throws NullPointerException if tasks or any element are null |
577 |
> |
* @throws RuntimeException or Error if any task did so |
578 |
|
*/ |
579 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
580 |
|
Throwable ex = null; |
610 |
|
} |
611 |
|
|
612 |
|
/** |
613 |
< |
* Forks all tasks in the collection, returning when |
614 |
< |
* {@code isDone} holds for all of them. If any task |
615 |
< |
* encounters an exception, others may be cancelled. This method |
616 |
< |
* may be invoked only from within ForkJoinTask |
617 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
618 |
< |
* exceptions or errors possibly including ClassCastException. |
613 |
> |
* Forks all tasks in the collection, returning when {@code |
614 |
> |
* isDone} holds for each task or an exception is encountered. If |
615 |
> |
* any task encounters an exception, others may be, but are not |
616 |
> |
* guaranteed to be, cancelled. This method may be invoked only |
617 |
> |
* from within ForkJoinTask computations (as may be determined |
618 |
> |
* using method {@link #inForkJoinPool}). Attempts to invoke in |
619 |
> |
* other contexts result in exceptions or errors, possibly |
620 |
> |
* including ClassCastException. |
621 |
> |
* |
622 |
|
* @param tasks the collection of tasks |
623 |
< |
* @throws NullPointerException if tasks or any element are null. |
624 |
< |
* @throws RuntimeException or Error if any task did so. |
625 |
< |
*/ |
626 |
< |
public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) { |
627 |
< |
if (!(tasks instanceof List)) { |
628 |
< |
invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()])); |
629 |
< |
return; |
623 |
> |
* @return the tasks argument, to simplify usage |
624 |
> |
* @throws NullPointerException if tasks or any element are null |
625 |
> |
* @throws RuntimeException or Error if any task did so |
626 |
> |
*/ |
627 |
> |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
628 |
> |
if (!(tasks instanceof List<?>)) { |
629 |
> |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
630 |
> |
return tasks; |
631 |
|
} |
632 |
+ |
@SuppressWarnings("unchecked") |
633 |
|
List<? extends ForkJoinTask<?>> ts = |
634 |
< |
(List<? extends ForkJoinTask<?>>)tasks; |
634 |
> |
(List<? extends ForkJoinTask<?>>) tasks; |
635 |
|
Throwable ex = null; |
636 |
|
int last = ts.size() - 1; |
637 |
|
for (int i = last; i >= 0; --i) { |
662 |
|
} |
663 |
|
if (ex != null) |
664 |
|
rethrowException(ex); |
665 |
+ |
return tasks; |
666 |
|
} |
667 |
|
|
668 |
|
/** |
669 |
< |
* Returns true if the computation performed by this task has |
670 |
< |
* completed (or has been cancelled). |
671 |
< |
* @return true if this computation has completed |
669 |
> |
* Returns {@code true} if the computation performed by this task |
670 |
> |
* has completed (or has been cancelled). |
671 |
> |
* |
672 |
> |
* @return {@code true} if this computation has completed |
673 |
|
*/ |
674 |
|
public final boolean isDone() { |
675 |
|
return status < 0; |
676 |
|
} |
677 |
|
|
678 |
|
/** |
679 |
< |
* Returns true if this task was cancelled. |
680 |
< |
* @return true if this task was cancelled |
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; |
686 |
|
|
687 |
|
/** |
688 |
|
* Asserts that the results of this task's computation will not be |
689 |
< |
* used. If a cancellation occurs before atempting to execute this |
690 |
< |
* task, then execution will be suppressed, {@code isCancelled} |
691 |
< |
* will report true, and {@code join} will result in a |
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 true, whether |
695 |
< |
* {@code join} will return normally or via an exception, or |
696 |
< |
* whether these behaviors will remain consistent upon repeated |
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. |
698 |
|
* |
699 |
|
* <p>This method may be overridden in subclasses, but if so, must |
700 |
|
* still ensure that these minimal properties hold. In particular, |
701 |
|
* the cancel method itself must not throw exceptions. |
702 |
|
* |
703 |
< |
* <p> This method is designed to be invoked by <em>other</em> |
703 |
> |
* <p>This method is designed to be invoked by <em>other</em> |
704 |
|
* tasks. To terminate the current task, you can just return or |
705 |
|
* throw an unchecked exception from its computation method, or |
706 |
< |
* invoke {@code completeExceptionally}. |
706 |
> |
* invoke {@link #completeExceptionally}. |
707 |
|
* |
708 |
|
* @param mayInterruptIfRunning this value is ignored in the |
709 |
|
* default implementation because tasks are not in general |
710 |
< |
* cancelled via interruption. |
710 |
> |
* cancelled via interruption |
711 |
|
* |
712 |
< |
* @return true if this task is now cancelled |
712 |
> |
* @return {@code true} if this task is now cancelled |
713 |
|
*/ |
714 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
715 |
|
setCompletion(CANCELLED); |
717 |
|
} |
718 |
|
|
719 |
|
/** |
720 |
< |
* Returns true if this task threw an exception or was cancelled |
721 |
< |
* @return true if this task threw an exception or was cancelled |
720 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
721 |
> |
* |
722 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
723 |
|
*/ |
724 |
|
public final boolean isCompletedAbnormally() { |
725 |
|
return (status & COMPLETION_MASK) < NORMAL; |
729 |
|
* Returns the exception thrown by the base computation, or a |
730 |
|
* CancellationException if cancelled, or null if none or if the |
731 |
|
* method has not yet completed. |
732 |
< |
* @return the exception, or null if none |
732 |
> |
* |
733 |
> |
* @return the exception, or {@code null} if none |
734 |
|
*/ |
735 |
|
public final Throwable getException() { |
736 |
|
int s = status & COMPLETION_MASK; |
747 |
|
* {@code join} and related operations. This method may be used |
748 |
|
* to induce exceptions in asynchronous tasks, or to force |
749 |
|
* completion of tasks that would not otherwise complete. Its use |
750 |
< |
* in other situations is likely to be wrong. This method is |
750 |
> |
* in other situations is discouraged. This method is |
751 |
|
* overridable, but overridden versions must invoke {@code super} |
752 |
|
* implementation to maintain guarantees. |
753 |
|
* |
757 |
|
*/ |
758 |
|
public void completeExceptionally(Throwable ex) { |
759 |
|
setDoneExceptionally((ex instanceof RuntimeException) || |
760 |
< |
(ex instanceof Error)? ex : |
760 |
> |
(ex instanceof Error) ? ex : |
761 |
|
new RuntimeException(ex)); |
762 |
|
} |
763 |
|
|
767 |
|
* operations. This method may be used to provide results for |
768 |
|
* asynchronous tasks, or to provide alternative handling for |
769 |
|
* tasks that would not otherwise complete normally. Its use in |
770 |
< |
* other situations is likely to be wrong. This method is |
770 |
> |
* other situations is discouraged. This method is |
771 |
|
* overridable, but overridden versions must invoke {@code super} |
772 |
|
* implementation to maintain guarantees. |
773 |
|
* |
774 |
< |
* @param value the result value for this task. |
774 |
> |
* @param value the result value for this task |
775 |
|
*/ |
776 |
|
public void complete(V value) { |
777 |
|
try { |
778 |
|
setRawResult(value); |
779 |
< |
} catch(Throwable rex) { |
779 |
> |
} catch (Throwable rex) { |
780 |
|
setDoneExceptionally(rex); |
781 |
|
return; |
782 |
|
} |
792 |
|
|
793 |
|
public final V get(long timeout, TimeUnit unit) |
794 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
795 |
+ |
long nanos = unit.toNanos(timeout); |
796 |
|
ForkJoinWorkerThread w = getWorker(); |
797 |
|
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
798 |
< |
awaitDone(w, unit.toNanos(timeout)); |
798 |
> |
awaitDone(w, nanos); |
799 |
|
return reportTimedFutureResult(); |
800 |
|
} |
801 |
|
|
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 potemtial dependencies between continuation of the |
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. Attempts to invoke in other contexts |
811 |
< |
* resul!t in exceptions or errors possibly including ClassCastException. |
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()); |
818 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
819 |
|
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
820 |
|
reportException(busyJoin(w)); |
821 |
|
return getRawResult(); |
824 |
|
/** |
825 |
|
* Possibly executes other tasks until this task is ready. This |
826 |
|
* method may be invoked only from within ForkJoinTask |
827 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
828 |
< |
* exceptions or errors possibly including ClassCastException. |
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()); |
834 |
> |
(ForkJoinWorkerThread) Thread.currentThread(); |
835 |
|
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
836 |
|
busyJoin(w); |
837 |
|
} |
867 |
|
* Possibly executes tasks until the pool hosting the current task |
868 |
|
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
869 |
|
* designs in which many tasks are forked, but none are explicitly |
870 |
< |
* joined, instead executing them until all are processed. |
870 |
> |
* joined, instead executing them until all are processed. This |
871 |
> |
* method may be invoked only from within ForkJoinTask |
872 |
> |
* computations (as may be determined using method {@link |
873 |
> |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
874 |
> |
* in exceptions or errors, possibly including ClassCastException. |
875 |
|
*/ |
876 |
|
public static void helpQuiesce() { |
877 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())). |
878 |
< |
helpQuiescePool(); |
877 |
> |
((ForkJoinWorkerThread) Thread.currentThread()) |
878 |
> |
.helpQuiescePool(); |
879 |
|
} |
880 |
|
|
881 |
|
/** |
885 |
|
* never been forked, or has been forked, then completed and all |
886 |
|
* outstanding joins of this task have also completed. Effects |
887 |
|
* under any other usage conditions are not guaranteed, and are |
888 |
< |
* almost surely wrong. This method may be useful when executing |
888 |
> |
* discouraged. This method may be useful when executing |
889 |
|
* pre-constructed trees of subtasks in loops. |
890 |
|
*/ |
891 |
|
public void reinitialize() { |
896 |
|
|
897 |
|
/** |
898 |
|
* Returns the pool hosting the current task execution, or null |
899 |
< |
* if this task is executing outside of any pool. |
900 |
< |
* @return the pool, or null if none. |
899 |
> |
* if this task is executing outside of any ForkJoinPool. |
900 |
> |
* |
901 |
> |
* @see #inForkJoinPool |
902 |
> |
* @return the pool, or {@code null} if none |
903 |
|
*/ |
904 |
|
public static ForkJoinPool getPool() { |
905 |
|
Thread t = Thread.currentThread(); |
906 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
907 |
< |
((ForkJoinWorkerThread)t).pool : null); |
906 |
> |
return (t instanceof ForkJoinWorkerThread) ? |
907 |
> |
((ForkJoinWorkerThread) t).pool : null; |
908 |
> |
} |
909 |
> |
|
910 |
> |
/** |
911 |
> |
* Returns {@code true} if the current thread is executing as a |
912 |
> |
* ForkJoinPool computation. |
913 |
> |
* |
914 |
> |
* @return {@code true} if the current thread is executing as a |
915 |
> |
* ForkJoinPool computation, or false otherwise |
916 |
> |
*/ |
917 |
> |
public static boolean inForkJoinPool() { |
918 |
> |
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
919 |
|
} |
920 |
|
|
921 |
|
/** |
925 |
|
* another thread. This method may be useful when arranging |
926 |
|
* alternative local processing of tasks that could have been, but |
927 |
|
* were not, stolen. This method may be invoked only from within |
928 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
929 |
< |
* result in exceptions or errors possibly including ClassCastException. |
930 |
< |
* @return true if unforked |
928 |
> |
* ForkJoinTask computations (as may be determined using method |
929 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
930 |
> |
* result in exceptions or errors, possibly including |
931 |
> |
* ClassCastException. |
932 |
> |
* |
933 |
> |
* @return {@code true} if unforked |
934 |
|
*/ |
935 |
|
public boolean tryUnfork() { |
936 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this); |
936 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
937 |
> |
.unpushTask(this); |
938 |
|
} |
939 |
|
|
940 |
|
/** |
941 |
|
* Returns an estimate of the number of tasks that have been |
942 |
|
* forked by the current worker thread but not yet executed. This |
943 |
|
* value may be useful for heuristic decisions about whether to |
944 |
< |
* fork other tasks. |
944 |
> |
* fork other tasks. This method may be invoked only from within |
945 |
> |
* ForkJoinTask computations (as may be determined using method |
946 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
947 |
> |
* result in exceptions or errors, possibly including |
948 |
> |
* ClassCastException. |
949 |
|
* @return the number of tasks |
950 |
|
*/ |
951 |
|
public static int getQueuedTaskCount() { |
952 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
953 |
< |
getQueueSize(); |
952 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
953 |
> |
.getQueueSize(); |
954 |
|
} |
955 |
|
|
956 |
|
/** |
957 |
< |
* Returns a estimate of how many more locally queued tasks are |
957 |
> |
* Returns an estimate of how many more locally queued tasks are |
958 |
|
* held by the current worker thread than there are other worker |
959 |
|
* threads that might steal them. This value may be useful for |
960 |
|
* heuristic decisions about whether to fork other tasks. In many |
961 |
|
* usages of ForkJoinTasks, at steady state, each worker should |
962 |
|
* aim to maintain a small constant surplus (for example, 3) of |
963 |
|
* tasks, and to process computations locally if this threshold is |
964 |
< |
* exceeded. |
964 |
> |
* exceeded. This method may be invoked only from within |
965 |
> |
* ForkJoinTask computations (as may be determined using method |
966 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
967 |
> |
* result in exceptions or errors, possibly including |
968 |
> |
* ClassCastException. * |
969 |
|
* @return the surplus number of tasks, which may be negative |
970 |
|
*/ |
971 |
|
public static int getSurplusQueuedTaskCount() { |
972 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())) |
972 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
973 |
|
.getEstimatedSurplusTaskCount(); |
974 |
|
} |
975 |
|
|
976 |
|
// Extension methods |
977 |
|
|
978 |
|
/** |
979 |
< |
* Returns the result that would be returned by {@code join}, |
980 |
< |
* even if this task completed abnormally, or null if this task is |
981 |
< |
* not known to have been completed. This method is designed to |
982 |
< |
* aid debugging, as well as to support extensions. Its use in any |
983 |
< |
* other context is discouraged. |
979 |
> |
* Returns the result that would be returned by {@link #join}, even |
980 |
> |
* if this task completed abnormally, or {@code null} if this task |
981 |
> |
* is not known to have been completed. This method is designed |
982 |
> |
* to aid debugging, as well as to support extensions. Its use in |
983 |
> |
* any other context is discouraged. |
984 |
|
* |
985 |
< |
* @return the result, or null if not completed. |
985 |
> |
* @return the result, or {@code null} if not completed |
986 |
|
*/ |
987 |
|
public abstract V getRawResult(); |
988 |
|
|
1001 |
|
* called otherwise. The return value controls whether this task |
1002 |
|
* is considered to be done normally. It may return false in |
1003 |
|
* asynchronous actions that require explicit invocations of |
1004 |
< |
* {@code complete} to become joinable. It may throw exceptions |
1004 |
> |
* {@link #complete} to become joinable. It may throw exceptions |
1005 |
|
* to indicate abnormal exit. |
1006 |
< |
* @return true if completed normally |
1006 |
> |
* |
1007 |
> |
* @return {@code true} if completed normally |
1008 |
|
* @throws Error or RuntimeException if encountered during computation |
1009 |
|
*/ |
1010 |
|
protected abstract boolean exec(); |
1011 |
|
|
1012 |
|
/** |
1013 |
< |
* Returns, but does not unschedule or execute, the task queued by |
1014 |
< |
* the current thread but not yet executed, if one is |
1013 |
> |
* Returns, but does not unschedule or execute, a task queued by |
1014 |
> |
* the current thread but not yet executed, if one is immediately |
1015 |
|
* available. There is no guarantee that this task will actually |
1016 |
< |
* be polled or executed next. This method is designed primarily |
1017 |
< |
* to support extensions, and is unlikely to be useful otherwise. |
1018 |
< |
* This method may be invoked only from within ForkJoinTask |
1019 |
< |
* computations. Attempts to invoke in other contexts result in |
1020 |
< |
* exceptions or errors possibly including ClassCastException. |
1016 |
> |
* be polled or executed next. Conversely, this method may return |
1017 |
> |
* null even if a task exists but cannot be accessed without |
1018 |
> |
* contention with other threads. This method is designed |
1019 |
> |
* primarily to support extensions, and is unlikely to be useful |
1020 |
> |
* otherwise. This method may be invoked only from within |
1021 |
> |
* ForkJoinTask computations (as may be determined using method |
1022 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1023 |
> |
* result in exceptions or errors, possibly including |
1024 |
> |
* ClassCastException. |
1025 |
|
* |
1026 |
< |
* @return the next task, or null if none are available |
1026 |
> |
* @return the next task, or {@code null} if none are available |
1027 |
|
*/ |
1028 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1029 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask(); |
1029 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1030 |
> |
.peekTask(); |
1031 |
|
} |
1032 |
|
|
1033 |
|
/** |
1035 |
|
* queued by the current thread but not yet executed. This method |
1036 |
|
* is designed primarily to support extensions, and is unlikely to |
1037 |
|
* be useful otherwise. This method may be invoked only from |
1038 |
< |
* within ForkJoinTask computations. Attempts to invoke in other |
1039 |
< |
* contexts result in exceptions or errors possibly including |
1038 |
> |
* within ForkJoinTask computations (as may be determined using |
1039 |
> |
* method {@link #inForkJoinPool}). Attempts to invoke in other |
1040 |
> |
* contexts result in exceptions or errors, possibly including |
1041 |
|
* ClassCastException. |
1042 |
|
* |
1043 |
< |
* @return the next task, or null if none are available |
1043 |
> |
* @return the next task, or {@code null} if none are available |
1044 |
|
*/ |
1045 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1046 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask(); |
1046 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1047 |
> |
.pollLocalTask(); |
1048 |
|
} |
1049 |
|
|
1050 |
|
/** |
1052 |
|
* queued by the current thread but not yet executed, if one is |
1053 |
|
* available, or if not available, a task that was forked by some |
1054 |
|
* other thread, if available. Availability may be transient, so a |
1055 |
< |
* {@code null} result does not necessarily imply quiecence |
1055 |
> |
* {@code null} result does not necessarily imply quiescence |
1056 |
|
* of the pool this task is operating in. This method is designed |
1057 |
|
* primarily to support extensions, and is unlikely to be useful |
1058 |
|
* otherwise. This method may be invoked only from within |
1059 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
1060 |
< |
* result in exceptions or errors possibly including |
1059 |
> |
* ForkJoinTask computations (as may be determined using method |
1060 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1061 |
> |
* result in exceptions or errors, possibly including |
1062 |
|
* ClassCastException. |
1063 |
|
* |
1064 |
< |
* @return a task, or null if none are available |
1064 |
> |
* @return a task, or {@code null} if none are available |
1065 |
|
*/ |
1066 |
|
protected static ForkJoinTask<?> pollTask() { |
1067 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1068 |
< |
pollTask(); |
1067 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1068 |
> |
.pollTask(); |
1069 |
> |
} |
1070 |
> |
|
1071 |
> |
/** |
1072 |
> |
* Adaptor for Runnables. This implements RunnableFuture |
1073 |
> |
* to be compliant with AbstractExecutorService constraints |
1074 |
> |
* when used in ForkJoinPool. |
1075 |
> |
*/ |
1076 |
> |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1077 |
> |
implements RunnableFuture<T> { |
1078 |
> |
final Runnable runnable; |
1079 |
> |
final T resultOnCompletion; |
1080 |
> |
T result; |
1081 |
> |
AdaptedRunnable(Runnable runnable, T result) { |
1082 |
> |
if (runnable == null) throw new NullPointerException(); |
1083 |
> |
this.runnable = runnable; |
1084 |
> |
this.resultOnCompletion = result; |
1085 |
> |
} |
1086 |
> |
public T getRawResult() { return result; } |
1087 |
> |
public void setRawResult(T v) { result = v; } |
1088 |
> |
public boolean exec() { |
1089 |
> |
runnable.run(); |
1090 |
> |
result = resultOnCompletion; |
1091 |
> |
return true; |
1092 |
> |
} |
1093 |
> |
public void run() { invoke(); } |
1094 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1095 |
> |
} |
1096 |
> |
|
1097 |
> |
/** |
1098 |
> |
* Adaptor for Callables |
1099 |
> |
*/ |
1100 |
> |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1101 |
> |
implements RunnableFuture<T> { |
1102 |
> |
final Callable<? extends T> callable; |
1103 |
> |
T result; |
1104 |
> |
AdaptedCallable(Callable<? extends T> callable) { |
1105 |
> |
if (callable == null) throw new NullPointerException(); |
1106 |
> |
this.callable = callable; |
1107 |
> |
} |
1108 |
> |
public T getRawResult() { return result; } |
1109 |
> |
public void setRawResult(T v) { result = v; } |
1110 |
> |
public boolean exec() { |
1111 |
> |
try { |
1112 |
> |
result = callable.call(); |
1113 |
> |
return true; |
1114 |
> |
} catch (Error err) { |
1115 |
> |
throw err; |
1116 |
> |
} catch (RuntimeException rex) { |
1117 |
> |
throw rex; |
1118 |
> |
} catch (Exception ex) { |
1119 |
> |
throw new RuntimeException(ex); |
1120 |
> |
} |
1121 |
> |
} |
1122 |
> |
public void run() { invoke(); } |
1123 |
> |
private static final long serialVersionUID = 2838392045355241008L; |
1124 |
> |
} |
1125 |
> |
|
1126 |
> |
/** |
1127 |
> |
* Returns a new ForkJoinTask that performs the {@code run} |
1128 |
> |
* method of the given Runnable as its action, and returns a null |
1129 |
> |
* result upon {@code join}. |
1130 |
> |
* |
1131 |
> |
* @param runnable the runnable action |
1132 |
> |
* @return the task |
1133 |
> |
*/ |
1134 |
> |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1135 |
> |
return new AdaptedRunnable<Void>(runnable, null); |
1136 |
> |
} |
1137 |
> |
|
1138 |
> |
/** |
1139 |
> |
* Returns a new ForkJoinTask that performs the {@code run} |
1140 |
> |
* method of the given Runnable as its action, and returns the |
1141 |
> |
* given result upon {@code join}. |
1142 |
> |
* |
1143 |
> |
* @param runnable the runnable action |
1144 |
> |
* @param result the result upon completion |
1145 |
> |
* @return the task |
1146 |
> |
*/ |
1147 |
> |
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1148 |
> |
return new AdaptedRunnable<T>(runnable, result); |
1149 |
> |
} |
1150 |
> |
|
1151 |
> |
/** |
1152 |
> |
* Returns a new ForkJoinTask that performs the {@code call} |
1153 |
> |
* method of the given Callable as its action, and returns its |
1154 |
> |
* result upon {@code join}, translating any checked |
1155 |
> |
* exceptions encountered into {@code RuntimeException}. |
1156 |
> |
* |
1157 |
> |
* @param callable the callable action |
1158 |
> |
* @return the task |
1159 |
> |
*/ |
1160 |
> |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1161 |
> |
return new AdaptedCallable<T>(callable); |
1162 |
|
} |
1163 |
|
|
1164 |
|
// Serialization support |
1169 |
|
* Save the state to a stream. |
1170 |
|
* |
1171 |
|
* @serialData the current run status and the exception thrown |
1172 |
< |
* during execution, or null if none. |
1172 |
> |
* during execution, or {@code null} if none |
1173 |
|
* @param s the stream |
1174 |
|
*/ |
1175 |
|
private void writeObject(java.io.ObjectOutputStream s) |
1180 |
|
|
1181 |
|
/** |
1182 |
|
* Reconstitute the instance from a stream. |
1183 |
+ |
* |
1184 |
|
* @param s the stream |
1185 |
|
*/ |
1186 |
|
private void readObject(java.io.ObjectInputStream s) |
1190 |
|
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1191 |
|
Object ex = s.readObject(); |
1192 |
|
if (ex != null) |
1193 |
< |
setDoneExceptionally((Throwable)ex); |
1193 |
> |
setDoneExceptionally((Throwable) ex); |
1194 |
|
} |
1195 |
|
|
1196 |
< |
// Temporary Unsafe mechanics for preliminary release |
1197 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1196 |
> |
// Unsafe mechanics |
1197 |
> |
|
1198 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1199 |
> |
private static final long statusOffset = |
1200 |
> |
objectFieldOffset("status", ForkJoinTask.class); |
1201 |
> |
|
1202 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1203 |
> |
try { |
1204 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1205 |
> |
} catch (NoSuchFieldException e) { |
1206 |
> |
// Convert Exception to corresponding Error |
1207 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1208 |
> |
error.initCause(e); |
1209 |
> |
throw error; |
1210 |
> |
} |
1211 |
> |
} |
1212 |
> |
|
1213 |
> |
/** |
1214 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1215 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1216 |
> |
* into a jdk. |
1217 |
> |
* |
1218 |
> |
* @return a sun.misc.Unsafe |
1219 |
> |
*/ |
1220 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1221 |
|
try { |
1222 |
< |
return Unsafe.getUnsafe(); |
1222 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1223 |
|
} catch (SecurityException se) { |
1224 |
|
try { |
1225 |
|
return java.security.AccessController.doPrivileged |
1226 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1227 |
< |
public Unsafe run() throws Exception { |
1228 |
< |
return getUnsafePrivileged(); |
1226 |
> |
(new java.security |
1227 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1228 |
> |
public sun.misc.Unsafe run() throws Exception { |
1229 |
> |
java.lang.reflect.Field f = sun.misc |
1230 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1231 |
> |
f.setAccessible(true); |
1232 |
> |
return (sun.misc.Unsafe) f.get(null); |
1233 |
|
}}); |
1234 |
|
} catch (java.security.PrivilegedActionException e) { |
1235 |
< |
throw e.getCause(); |
1235 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1236 |
> |
e.getCause()); |
1237 |
|
} |
1238 |
|
} |
1239 |
|
} |
1026 |
– |
|
1027 |
– |
private static Unsafe getUnsafePrivileged() |
1028 |
– |
throws NoSuchFieldException, IllegalAccessException { |
1029 |
– |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1030 |
– |
f.setAccessible(true); |
1031 |
– |
return (Unsafe) f.get(null); |
1032 |
– |
} |
1033 |
– |
|
1034 |
– |
private static long fieldOffset(String fieldName) |
1035 |
– |
throws NoSuchFieldException { |
1036 |
– |
return _unsafe.objectFieldOffset |
1037 |
– |
(ForkJoinTask.class.getDeclaredField(fieldName)); |
1038 |
– |
} |
1039 |
– |
|
1040 |
– |
static final Unsafe _unsafe; |
1041 |
– |
static final long statusOffset; |
1042 |
– |
|
1043 |
– |
static { |
1044 |
– |
try { |
1045 |
– |
_unsafe = getUnsafe(); |
1046 |
– |
statusOffset = fieldOffset("status"); |
1047 |
– |
} catch (Throwable e) { |
1048 |
– |
throw new RuntimeException("Could not initialize intrinsics", e); |
1049 |
– |
} |
1050 |
– |
} |
1051 |
– |
|
1240 |
|
} |