1 |
jsr166 |
1.1 |
/* |
2 |
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
|
|
* Expert Group and released to the public domain, as explained at |
4 |
jsr166 |
1.48 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
5 |
jsr166 |
1.1 |
*/ |
6 |
|
|
|
7 |
|
|
package java.util.concurrent; |
8 |
|
|
|
9 |
|
|
import java.io.Serializable; |
10 |
dl |
1.109 |
import java.lang.invoke.MethodHandles; |
11 |
|
|
import java.lang.invoke.VarHandle; |
12 |
jsr166 |
1.90 |
import java.lang.ref.ReferenceQueue; |
13 |
|
|
import java.lang.ref.WeakReference; |
14 |
|
|
import java.lang.reflect.Constructor; |
15 |
jsr166 |
1.1 |
import java.util.Collection; |
16 |
|
|
import java.util.List; |
17 |
jsr166 |
1.7 |
import java.util.RandomAccess; |
18 |
dl |
1.124 |
import java.util.concurrent.locks.LockSupport; |
19 |
jsr166 |
1.1 |
|
20 |
|
|
/** |
21 |
jsr166 |
1.6 |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
22 |
|
|
* A {@code ForkJoinTask} is a thread-like entity that is much |
23 |
jsr166 |
1.1 |
* lighter weight than a normal thread. Huge numbers of tasks and |
24 |
|
|
* subtasks may be hosted by a small number of actual threads in a |
25 |
|
|
* ForkJoinPool, at the price of some usage limitations. |
26 |
|
|
* |
27 |
dl |
1.64 |
* <p>A "main" {@code ForkJoinTask} begins execution when it is |
28 |
|
|
* explicitly submitted to a {@link ForkJoinPool}, or, if not already |
29 |
|
|
* engaged in a ForkJoin computation, commenced in the {@link |
30 |
dl |
1.67 |
* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or |
31 |
dl |
1.64 |
* related methods. Once started, it will usually in turn start other |
32 |
|
|
* subtasks. As indicated by the name of this class, many programs |
33 |
|
|
* using {@code ForkJoinTask} employ only methods {@link #fork} and |
34 |
|
|
* {@link #join}, or derivatives such as {@link |
35 |
jsr166 |
1.27 |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
36 |
|
|
* provides a number of other methods that can come into play in |
37 |
dl |
1.64 |
* advanced usages, as well as extension mechanics that allow support |
38 |
|
|
* of new forms of fork/join processing. |
39 |
jsr166 |
1.1 |
* |
40 |
jsr166 |
1.6 |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
41 |
|
|
* The efficiency of {@code ForkJoinTask}s stems from a set of |
42 |
|
|
* restrictions (that are only partially statically enforceable) |
43 |
dl |
1.54 |
* reflecting their main use as computational tasks calculating pure |
44 |
|
|
* functions or operating on purely isolated objects. The primary |
45 |
|
|
* coordination mechanisms are {@link #fork}, that arranges |
46 |
jsr166 |
1.6 |
* asynchronous execution, and {@link #join}, that doesn't proceed |
47 |
|
|
* until the task's result has been computed. Computations should |
48 |
dl |
1.54 |
* ideally avoid {@code synchronized} methods or blocks, and should |
49 |
|
|
* minimize other blocking synchronization apart from joining other |
50 |
|
|
* tasks or using synchronizers such as Phasers that are advertised to |
51 |
|
|
* cooperate with fork/join scheduling. Subdividable tasks should also |
52 |
jsr166 |
1.68 |
* not perform blocking I/O, and should ideally access variables that |
53 |
dl |
1.54 |
* are completely independent of those accessed by other running |
54 |
|
|
* tasks. These guidelines are loosely enforced by not permitting |
55 |
|
|
* checked exceptions such as {@code IOExceptions} to be |
56 |
|
|
* thrown. However, computations may still encounter unchecked |
57 |
|
|
* exceptions, that are rethrown to callers attempting to join |
58 |
|
|
* them. These exceptions may additionally include {@link |
59 |
|
|
* RejectedExecutionException} stemming from internal resource |
60 |
|
|
* exhaustion, such as failure to allocate internal task |
61 |
|
|
* queues. Rethrown exceptions behave in the same way as regular |
62 |
|
|
* exceptions, but, when possible, contain stack traces (as displayed |
63 |
|
|
* for example using {@code ex.printStackTrace()}) of both the thread |
64 |
|
|
* that initiated the computation as well as the thread actually |
65 |
|
|
* encountering the exception; minimally only the latter. |
66 |
|
|
* |
67 |
|
|
* <p>It is possible to define and use ForkJoinTasks that may block, |
68 |
jsr166 |
1.110 |
* but doing so requires three further considerations: (1) Completion |
69 |
dl |
1.54 |
* of few if any <em>other</em> tasks should be dependent on a task |
70 |
jsr166 |
1.68 |
* that blocks on external synchronization or I/O. Event-style async |
71 |
dl |
1.63 |
* tasks that are never joined (for example, those subclassing {@link |
72 |
|
|
* CountedCompleter}) often fall into this category. (2) To minimize |
73 |
|
|
* resource impact, tasks should be small; ideally performing only the |
74 |
|
|
* (possibly) blocking action. (3) Unless the {@link |
75 |
dl |
1.54 |
* ForkJoinPool.ManagedBlocker} API is used, or the number of possibly |
76 |
|
|
* blocked tasks is known to be less than the pool's {@link |
77 |
|
|
* ForkJoinPool#getParallelism} level, the pool cannot guarantee that |
78 |
|
|
* enough threads will be available to ensure progress or good |
79 |
|
|
* performance. |
80 |
jsr166 |
1.1 |
* |
81 |
|
|
* <p>The primary method for awaiting completion and extracting |
82 |
|
|
* results of a task is {@link #join}, but there are several variants: |
83 |
|
|
* The {@link Future#get} methods support interruptible and/or timed |
84 |
|
|
* waits for completion and report results using {@code Future} |
85 |
dl |
1.16 |
* conventions. Method {@link #invoke} is semantically |
86 |
jsr166 |
1.8 |
* equivalent to {@code fork(); join()} but always attempts to begin |
87 |
|
|
* execution in the current thread. The "<em>quiet</em>" forms of |
88 |
|
|
* these methods do not extract results or report exceptions. These |
89 |
jsr166 |
1.1 |
* may be useful when a set of tasks are being executed, and you need |
90 |
|
|
* to delay processing of results or exceptions until all complete. |
91 |
|
|
* Method {@code invokeAll} (available in multiple versions) |
92 |
|
|
* performs the most common form of parallel invocation: forking a set |
93 |
|
|
* of tasks and joining them all. |
94 |
|
|
* |
95 |
jsr166 |
1.57 |
* <p>In the most typical usages, a fork-join pair act like a call |
96 |
dl |
1.54 |
* (fork) and return (join) from a parallel recursive function. As is |
97 |
|
|
* the case with other forms of recursive calls, returns (joins) |
98 |
|
|
* should be performed innermost-first. For example, {@code a.fork(); |
99 |
|
|
* b.fork(); b.join(); a.join();} is likely to be substantially more |
100 |
|
|
* efficient than joining {@code a} before {@code b}. |
101 |
|
|
* |
102 |
jsr166 |
1.8 |
* <p>The execution status of tasks may be queried at several levels |
103 |
|
|
* of detail: {@link #isDone} is true if a task completed in any way |
104 |
|
|
* (including the case where a task was cancelled without executing); |
105 |
|
|
* {@link #isCompletedNormally} is true if a task completed without |
106 |
jsr166 |
1.10 |
* cancellation or encountering an exception; {@link #isCancelled} is |
107 |
|
|
* true if the task was cancelled (in which case {@link #getException} |
108 |
jsr166 |
1.115 |
* returns a {@link CancellationException}); and |
109 |
jsr166 |
1.10 |
* {@link #isCompletedAbnormally} is true if a task was either |
110 |
|
|
* cancelled or encountered an exception, in which case {@link |
111 |
|
|
* #getException} will return either the encountered exception or |
112 |
jsr166 |
1.115 |
* {@link CancellationException}. |
113 |
jsr166 |
1.8 |
* |
114 |
jsr166 |
1.6 |
* <p>The ForkJoinTask class is not usually directly subclassed. |
115 |
jsr166 |
1.1 |
* Instead, you subclass one of the abstract classes that support a |
116 |
jsr166 |
1.6 |
* particular style of fork/join processing, typically {@link |
117 |
dl |
1.62 |
* RecursiveAction} for most computations that do not return results, |
118 |
|
|
* {@link RecursiveTask} for those that do, and {@link |
119 |
|
|
* CountedCompleter} for those in which completed actions trigger |
120 |
|
|
* other actions. Normally, a concrete ForkJoinTask subclass declares |
121 |
|
|
* fields comprising its parameters, established in a constructor, and |
122 |
|
|
* then defines a {@code compute} method that somehow uses the control |
123 |
dl |
1.64 |
* methods supplied by this base class. |
124 |
jsr166 |
1.1 |
* |
125 |
dl |
1.38 |
* <p>Method {@link #join} and its variants are appropriate for use |
126 |
|
|
* only when completion dependencies are acyclic; that is, the |
127 |
|
|
* parallel computation can be described as a directed acyclic graph |
128 |
|
|
* (DAG). Otherwise, executions may encounter a form of deadlock as |
129 |
|
|
* tasks cyclically wait for each other. However, this framework |
130 |
|
|
* supports other methods and techniques (for example the use of |
131 |
|
|
* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
132 |
|
|
* may be of use in constructing custom subclasses for problems that |
133 |
jsr166 |
1.79 |
* are not statically structured as DAGs. To support such usages, a |
134 |
dl |
1.63 |
* ForkJoinTask may be atomically <em>tagged</em> with a {@code short} |
135 |
|
|
* value using {@link #setForkJoinTaskTag} or {@link |
136 |
dl |
1.60 |
* #compareAndSetForkJoinTaskTag} and checked using {@link |
137 |
dl |
1.63 |
* #getForkJoinTaskTag}. The ForkJoinTask implementation does not use |
138 |
|
|
* these {@code protected} methods or tags for any purpose, but they |
139 |
|
|
* may be of use in the construction of specialized subclasses. For |
140 |
|
|
* example, parallel graph traversals can use the supplied methods to |
141 |
|
|
* avoid revisiting nodes/tasks that have already been processed. |
142 |
|
|
* (Method names for tagging are bulky in part to encourage definition |
143 |
|
|
* of methods that reflect their usage patterns.) |
144 |
dl |
1.38 |
* |
145 |
jsr166 |
1.7 |
* <p>Most base support methods are {@code final}, to prevent |
146 |
|
|
* overriding of implementations that are intrinsically tied to the |
147 |
|
|
* underlying lightweight task scheduling framework. Developers |
148 |
|
|
* creating new basic styles of fork/join processing should minimally |
149 |
|
|
* implement {@code protected} methods {@link #exec}, {@link |
150 |
|
|
* #setRawResult}, and {@link #getRawResult}, while also introducing |
151 |
|
|
* an abstract computational method that can be implemented in its |
152 |
|
|
* subclasses, possibly relying on other {@code protected} methods |
153 |
|
|
* provided by this class. |
154 |
jsr166 |
1.1 |
* |
155 |
|
|
* <p>ForkJoinTasks should perform relatively small amounts of |
156 |
jsr166 |
1.7 |
* computation. Large tasks should be split into smaller subtasks, |
157 |
|
|
* usually via recursive decomposition. As a very rough rule of thumb, |
158 |
|
|
* a task should perform more than 100 and less than 10000 basic |
159 |
dl |
1.40 |
* computational steps, and should avoid indefinite looping. If tasks |
160 |
|
|
* are too big, then parallelism cannot improve throughput. If too |
161 |
|
|
* small, then memory and internal task maintenance overhead may |
162 |
|
|
* overwhelm processing. |
163 |
jsr166 |
1.1 |
* |
164 |
jsr166 |
1.8 |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
165 |
|
|
* and {@link Callable}, that may be of use when mixing execution of |
166 |
dl |
1.16 |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
167 |
|
|
* of this form, consider using a pool constructed in <em>asyncMode</em>. |
168 |
jsr166 |
1.6 |
* |
169 |
jsr166 |
1.7 |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
170 |
|
|
* used in extensions such as remote execution frameworks. It is |
171 |
|
|
* sensible to serialize tasks only before or after, but not during, |
172 |
|
|
* execution. Serialization is not relied on during execution itself. |
173 |
jsr166 |
1.1 |
* |
174 |
|
|
* @since 1.7 |
175 |
|
|
* @author Doug Lea |
176 |
|
|
*/ |
177 |
|
|
public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
178 |
|
|
|
179 |
dl |
1.13 |
/* |
180 |
|
|
* See the internal documentation of class ForkJoinPool for a |
181 |
|
|
* general implementation overview. ForkJoinTasks are mainly |
182 |
|
|
* responsible for maintaining their "status" field amidst relays |
183 |
jsr166 |
1.51 |
* to methods in ForkJoinWorkerThread and ForkJoinPool. |
184 |
|
|
* |
185 |
|
|
* The methods of this class are more-or-less layered into |
186 |
|
|
* (1) basic status maintenance |
187 |
|
|
* (2) execution and awaiting completion |
188 |
|
|
* (3) user-level methods that additionally report results. |
189 |
|
|
* This is sometimes hard to see because this file orders exported |
190 |
|
|
* methods in a way that flows well in javadocs. |
191 |
dl |
1.118 |
* |
192 |
dl |
1.124 |
* Revision notes: The use of "Aux" field replaces previous |
193 |
|
|
* reliance on a table to hold exceptions and synchronized blocks |
194 |
|
|
* and monitors to wait for completion. |
195 |
dl |
1.118 |
*/ |
196 |
jsr166 |
1.1 |
|
197 |
|
|
/** |
198 |
dl |
1.124 |
* Nodes for threads waiting for completion, or holding a thrown |
199 |
|
|
* exception (never both). Waiting threads prepend nodes |
200 |
|
|
* Treiber-stack-style. Signallers detach and unpark |
201 |
|
|
* waiters. Cancelled waiters try to unsplice. |
202 |
|
|
*/ |
203 |
|
|
static final class Aux { |
204 |
|
|
final Thread thread; |
205 |
|
|
final Throwable ex; // null if a waiter |
206 |
|
|
Aux next; // accessed only via memory-acquire chains |
207 |
|
|
Aux(Thread thread, Throwable ex) { |
208 |
|
|
this.thread = thread; |
209 |
|
|
this.ex = ex; |
210 |
|
|
} |
211 |
|
|
final boolean casNext(Aux c, Aux v) { // used only in cancellation |
212 |
|
|
return NEXT.compareAndSet(this, c, v); |
213 |
|
|
} |
214 |
|
|
private static final VarHandle NEXT; |
215 |
|
|
static { |
216 |
|
|
try { |
217 |
|
|
NEXT = MethodHandles.lookup() |
218 |
|
|
.findVarHandle(Aux.class, "next", Aux.class); |
219 |
|
|
} catch (ReflectiveOperationException e) { |
220 |
|
|
throw new ExceptionInInitializerError(e); |
221 |
dl |
1.13 |
} |
222 |
|
|
} |
223 |
jsr166 |
1.1 |
} |
224 |
|
|
|
225 |
dl |
1.124 |
/* |
226 |
|
|
* The status field holds bits packed into a single int to ensure |
227 |
|
|
* atomicity. Status is initially zero, and takes on nonnegative |
228 |
|
|
* values until completed, upon which it holds (sign bit) DONE, |
229 |
|
|
* possibly with ABNORMAL (cancelled or exceptional) and THROWN |
230 |
dl |
1.128 |
* (in which case an exception has been stored). A value of |
231 |
|
|
* ABNORMAL without DONE signifies an interrupted wait. These |
232 |
|
|
* control bits occupy only (some of) the upper half (16 bits) of |
233 |
|
|
* status field. The lower bits are used for user-defined tags. |
234 |
jsr166 |
1.1 |
*/ |
235 |
dl |
1.124 |
private static final int DONE = 1 << 31; // must be negative |
236 |
dl |
1.128 |
private static final int ABNORMAL = 1 << 16; |
237 |
|
|
private static final int THROWN = 1 << 17; |
238 |
dl |
1.124 |
private static final int SMASK = 0xffff; // short bits for tags |
239 |
|
|
// sentinels can be any positive upper half value: |
240 |
|
|
static final int ADJUST = 1 << 16; // uncompensate after block |
241 |
|
|
|
242 |
|
|
// Fields |
243 |
|
|
volatile int status; // accessed directly by pool and workers |
244 |
|
|
private transient volatile Aux aux; // either waiters or thrown Exception |
245 |
dl |
1.128 |
|
246 |
dl |
1.124 |
// Support for atomic operations |
247 |
|
|
private static final VarHandle STATUS; |
248 |
|
|
private static final VarHandle AUX; |
249 |
|
|
private int getAndBitwiseOrStatus(int v) { |
250 |
|
|
return (int)STATUS.getAndBitwiseOr(this, v); |
251 |
|
|
} |
252 |
|
|
private boolean casStatus(int c, int v) { |
253 |
|
|
return STATUS.weakCompareAndSet(this, c, v); |
254 |
|
|
} |
255 |
|
|
private boolean casAux(Aux c, Aux v) { |
256 |
|
|
return AUX.compareAndSet(this, c, v); |
257 |
|
|
} |
258 |
|
|
|
259 |
|
|
/** Removes and unparks waiters */ |
260 |
|
|
private void signalWaiters() { |
261 |
|
|
for (Aux a; (a = aux) != null && a.ex == null; ) { |
262 |
|
|
if (casAux(a, null)) { // detach entire list |
263 |
|
|
for (Thread t; a != null; a = a.next) { |
264 |
|
|
if ((t = a.thread) != Thread.currentThread() && t != null) |
265 |
|
|
LockSupport.unpark(t); // don't self-signal |
266 |
|
|
} |
267 |
|
|
break; |
268 |
dl |
1.54 |
} |
269 |
jsr166 |
1.1 |
} |
270 |
|
|
} |
271 |
|
|
|
272 |
|
|
/** |
273 |
dl |
1.124 |
* Possibly blocks until task is done or interrupted or timed out. |
274 |
dl |
1.87 |
* |
275 |
dl |
1.124 |
* @param interruptible true if wait can be cancelled by interrupt |
276 |
|
|
* @param deadline if non-zero use timed waits and possibly timeout |
277 |
dl |
1.128 |
* @param adjust if true, uncompensate pool after unblocking |
278 |
|
|
* @param pool if nonull, current pool (possibly comonPool if unknown) |
279 |
|
|
* @return status on exit, or ABNORMAL if interrupted while waiting |
280 |
dl |
1.124 |
*/ |
281 |
dl |
1.128 |
private int awaitDone(boolean interruptible, long deadline, boolean adjust, |
282 |
dl |
1.126 |
ForkJoinPool pool) { |
283 |
dl |
1.128 |
int s; Aux node = null; boolean interrupted = false, queued = false; |
284 |
|
|
long nanos = 0L; |
285 |
dl |
1.126 |
try { |
286 |
dl |
1.128 |
for (Aux a;;) { |
287 |
dl |
1.126 |
if ((s = status) < 0) |
288 |
dl |
1.124 |
break; |
289 |
dl |
1.126 |
else if (node == null) |
290 |
|
|
node = new Aux(Thread.currentThread(), null); |
291 |
|
|
else if (!queued) { |
292 |
|
|
if ((a = aux) != null && a.ex != null) |
293 |
|
|
Thread.onSpinWait(); // exception in progress |
294 |
|
|
else if (queued = casAux(node.next = a, node)) |
295 |
|
|
LockSupport.setCurrentBlocker(this); |
296 |
dl |
1.124 |
} |
297 |
dl |
1.128 |
else if (Thread.interrupted()) { |
298 |
|
|
if (interruptible) { |
299 |
|
|
s = ABNORMAL; |
300 |
dl |
1.126 |
break; |
301 |
|
|
} |
302 |
dl |
1.128 |
interrupted = true; |
303 |
dl |
1.124 |
} |
304 |
dl |
1.128 |
else if (pool != null && pool.isStopping()) |
305 |
|
|
casStatus(s, s | (DONE | ABNORMAL)); // help cancel |
306 |
|
|
else if (deadline != 0L && |
307 |
|
|
(nanos = deadline - System.nanoTime()) <= 0L) |
308 |
|
|
break; // timeout |
309 |
|
|
else if ((s = status) < 0) |
310 |
|
|
break; // recheck |
311 |
|
|
else if (nanos > 0L) |
312 |
|
|
LockSupport.parkNanos(nanos); |
313 |
|
|
else |
314 |
|
|
LockSupport.park(); |
315 |
dl |
1.87 |
} |
316 |
dl |
1.128 |
} finally { |
317 |
|
|
if (adjust && pool != null) |
318 |
|
|
pool.uncompensate(); |
319 |
|
|
} |
320 |
|
|
if (queued) { |
321 |
|
|
LockSupport.setCurrentBlocker(null); |
322 |
|
|
if (s >= 0) { // try to unsplice after cancellation |
323 |
|
|
outer: for (Aux a; (a = aux) != null && a.ex == null; ) { |
324 |
|
|
for (Aux trail = null;;) { |
325 |
|
|
Aux next = a.next; |
326 |
|
|
if (a == node) { |
327 |
|
|
if (trail != null) |
328 |
|
|
trail.casNext(trail, next); |
329 |
|
|
else if (casAux(a, next)) |
330 |
|
|
break outer; // cannot be re-encountered |
331 |
|
|
break; // restart |
332 |
|
|
} else { |
333 |
|
|
trail = a; |
334 |
|
|
if ((a = next) == null) |
335 |
|
|
break outer; |
336 |
dl |
1.126 |
} |
337 |
dl |
1.40 |
} |
338 |
dl |
1.87 |
} |
339 |
dl |
1.118 |
} |
340 |
dl |
1.128 |
else { |
341 |
|
|
signalWaiters(); // help clean or signal |
342 |
|
|
if (interrupted) |
343 |
|
|
Thread.currentThread().interrupt(); |
344 |
|
|
} |
345 |
dl |
1.19 |
} |
346 |
dl |
1.45 |
return s; |
347 |
dl |
1.19 |
} |
348 |
|
|
|
349 |
|
|
/** |
350 |
dl |
1.124 |
* Sets DONE status and wakes up threads waiting to join this task. |
351 |
|
|
* @return status on exit |
352 |
jsr166 |
1.1 |
*/ |
353 |
dl |
1.124 |
private int setDone() { |
354 |
|
|
int s = getAndBitwiseOrStatus(DONE) | DONE; |
355 |
|
|
signalWaiters(); |
356 |
dl |
1.45 |
return s; |
357 |
|
|
} |
358 |
|
|
|
359 |
|
|
/** |
360 |
dl |
1.124 |
* Sets ABNORMAL DONE status unless already done, and wakes up threads |
361 |
|
|
* waiting to join this task. |
362 |
|
|
* @return status on exit |
363 |
dl |
1.118 |
*/ |
364 |
dl |
1.124 |
private int trySetCancelled() { |
365 |
dl |
1.118 |
int s; |
366 |
dl |
1.124 |
do {} while ((s = status) >= 0 && !casStatus(s, s |= (DONE | ABNORMAL))); |
367 |
|
|
signalWaiters(); |
368 |
|
|
return s; |
369 |
dl |
1.118 |
} |
370 |
|
|
|
371 |
|
|
/** |
372 |
dl |
1.124 |
* Records exception and sets ABNORMAL THROWN DONE status unless |
373 |
|
|
* already done, and wakes up threads waiting to join this task. |
374 |
|
|
* If losing a race with setDone or trySetCancelled, the exception |
375 |
|
|
* may be recorded but not reported. |
376 |
dl |
1.54 |
* |
377 |
dl |
1.124 |
* @return status on exit |
378 |
dl |
1.45 |
*/ |
379 |
dl |
1.124 |
final int trySetThrown(Throwable ex) { |
380 |
|
|
Aux h = new Aux(Thread.currentThread(), ex), p = null; |
381 |
|
|
boolean installed = false; |
382 |
|
|
int s; |
383 |
|
|
while ((s = status) >= 0) { |
384 |
|
|
Aux a; |
385 |
|
|
if (!installed && ((a = aux) == null || a.ex == null) && |
386 |
|
|
(installed = casAux(a, h))) |
387 |
|
|
p = a; // list of waiters replaced by h |
388 |
|
|
if (installed && casStatus(s, s |= (DONE | ABNORMAL | THROWN))) |
389 |
|
|
break; |
390 |
|
|
} |
391 |
|
|
for (; p != null; p = p.next) |
392 |
|
|
LockSupport.unpark(p.thread); |
393 |
|
|
return s; |
394 |
jsr166 |
1.1 |
} |
395 |
|
|
|
396 |
|
|
/** |
397 |
dl |
1.124 |
* Records exception unless already done. Overridable in subclasses. |
398 |
dl |
1.54 |
* |
399 |
dl |
1.124 |
* @return status on exit |
400 |
jsr166 |
1.1 |
*/ |
401 |
dl |
1.124 |
int trySetException(Throwable ex) { |
402 |
|
|
return trySetThrown(ex); |
403 |
dl |
1.45 |
} |
404 |
|
|
|
405 |
dl |
1.124 |
static boolean isExceptionalStatus(int s) { // needed by subclasses |
406 |
|
|
return (s & THROWN) != 0; |
407 |
dl |
1.45 |
} |
408 |
|
|
|
409 |
|
|
/** |
410 |
dl |
1.124 |
* Unless done, calls exec and records status if completed, but |
411 |
|
|
* doesn't wait for completion otherwise. |
412 |
dl |
1.45 |
* |
413 |
dl |
1.124 |
* @return status on exit from this method |
414 |
dl |
1.45 |
*/ |
415 |
dl |
1.124 |
final int doExec() { |
416 |
|
|
int s; boolean completed; |
417 |
dl |
1.62 |
if ((s = status) >= 0) { |
418 |
|
|
try { |
419 |
dl |
1.124 |
completed = exec(); |
420 |
|
|
} catch (Throwable rex) { |
421 |
|
|
s = trySetException(rex); |
422 |
|
|
completed = false; |
423 |
dl |
1.45 |
} |
424 |
dl |
1.124 |
if (completed) |
425 |
|
|
s = setDone(); |
426 |
dl |
1.45 |
} |
427 |
dl |
1.62 |
return s; |
428 |
|
|
} |
429 |
|
|
|
430 |
|
|
/** |
431 |
dl |
1.128 |
* Helps and/or waits for completion from join, or async invoke if ran true. |
432 |
dl |
1.63 |
* |
433 |
dl |
1.128 |
* @param ran true if task known to have been exec'd |
434 |
|
|
* @return status on exit |
435 |
dl |
1.63 |
*/ |
436 |
dl |
1.128 |
private int awaitJoin(boolean ran) { |
437 |
|
|
boolean adjust = false, owned; |
438 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread wt; |
439 |
dl |
1.128 |
ForkJoinPool p; ForkJoinPool.WorkQueue q; int s; |
440 |
dl |
1.126 |
if (owned = ((t = Thread.currentThread()) |
441 |
|
|
instanceof ForkJoinWorkerThread)) { |
442 |
dl |
1.124 |
p = (wt = (ForkJoinWorkerThread)t).pool; |
443 |
|
|
q = wt.workQueue; |
444 |
|
|
} |
445 |
dl |
1.126 |
else { |
446 |
|
|
p = ForkJoinPool.common; |
447 |
|
|
q = ForkJoinPool.commonQueue(); |
448 |
dl |
1.124 |
} |
449 |
dl |
1.128 |
if (q != null && p != null) { |
450 |
|
|
if ((this instanceof CountedCompleter) ? |
451 |
|
|
(s = p.helpComplete(this, q, owned)) < 0 : |
452 |
|
|
(!ran && q.tryRemove(this, owned) && (s = doExec()) < 0)) |
453 |
|
|
return s; |
454 |
|
|
else if (owned) { |
455 |
|
|
if ((s = p.helpJoin(this, q)) < 0) |
456 |
|
|
return s; |
457 |
|
|
else if (s == ADJUST) |
458 |
|
|
adjust = true; |
459 |
|
|
} |
460 |
|
|
} |
461 |
|
|
return awaitDone(false, 0L, adjust, p); |
462 |
|
|
} |
463 |
|
|
|
464 |
|
|
/** |
465 |
|
|
* Helps and/or waits for completion from get. |
466 |
|
|
* |
467 |
|
|
* @param timed if true use timed wait |
468 |
|
|
* @param nanos wait time |
469 |
|
|
* @return status on exit, or ABNORMAL if interruptible and interrupted |
470 |
|
|
*/ |
471 |
|
|
private int awaitGet(boolean timed, long nanos) { |
472 |
|
|
boolean adjust = false, owned; |
473 |
|
|
Thread t; ForkJoinWorkerThread wt; |
474 |
|
|
ForkJoinPool p; ForkJoinPool.WorkQueue q; int s; long deadline; |
475 |
|
|
if (owned = ((t = Thread.currentThread()) |
476 |
|
|
instanceof ForkJoinWorkerThread)) { |
477 |
|
|
p = (wt = (ForkJoinWorkerThread)t).pool; |
478 |
|
|
q = wt.workQueue; |
479 |
|
|
} |
480 |
|
|
else if (!Thread.interrupted()) { |
481 |
|
|
p = ForkJoinPool.common; |
482 |
|
|
q = ForkJoinPool.commonQueue(); |
483 |
|
|
} |
484 |
|
|
else |
485 |
|
|
return ABNORMAL; |
486 |
|
|
if (!timed) |
487 |
|
|
deadline = 0L; |
488 |
|
|
else if (nanos <= 0L) |
489 |
|
|
return 0; |
490 |
|
|
else if ((deadline = nanos + System.nanoTime()) == 0L) |
491 |
|
|
deadline = 1L; |
492 |
|
|
if (q != null && p != null) { |
493 |
|
|
if ((!timed || p.isSaturated()) && |
494 |
|
|
((this instanceof CountedCompleter) ? |
495 |
|
|
(s = p.helpComplete(this, q, owned)) < 0 : |
496 |
|
|
(q.tryRemove(this, owned) && (s = doExec()) < 0))) |
497 |
|
|
return s; |
498 |
|
|
else if (owned) { |
499 |
|
|
if ((s = p.helpJoin(this, q)) < 0) |
500 |
|
|
return s; |
501 |
|
|
else if (s == ADJUST) |
502 |
|
|
adjust = true; |
503 |
|
|
} |
504 |
|
|
} |
505 |
|
|
return awaitDone(!owned, deadline, adjust, p); |
506 |
dl |
1.45 |
} |
507 |
|
|
|
508 |
|
|
/** |
509 |
dl |
1.128 |
* Cancels, ignoring any exceptions thrown by cancel. Cancel is |
510 |
|
|
* spec'ed not to throw any exceptions, but if it does anyway, we |
511 |
|
|
* have no recourse, so guard against this case. |
512 |
dl |
1.54 |
*/ |
513 |
dl |
1.128 |
static final void cancelIgnoringExceptions(Future<?> t) { |
514 |
dl |
1.124 |
if (t != null) { |
515 |
dl |
1.54 |
try { |
516 |
|
|
t.cancel(false); |
517 |
|
|
} catch (Throwable ignore) { |
518 |
|
|
} |
519 |
|
|
} |
520 |
|
|
} |
521 |
|
|
|
522 |
|
|
/** |
523 |
jsr166 |
1.105 |
* Returns a rethrowable exception for this task, if available. |
524 |
|
|
* To provide accurate stack traces, if the exception was not |
525 |
|
|
* thrown by the current thread, we try to create a new exception |
526 |
|
|
* of the same type as the one thrown, but with the recorded |
527 |
|
|
* exception as its cause. If there is no such constructor, we |
528 |
|
|
* instead try to use a no-arg constructor, followed by initCause, |
529 |
|
|
* to the same effect. If none of these apply, or any fail due to |
530 |
|
|
* other exceptions, we return the recorded exception, which is |
531 |
|
|
* still correct, although it may contain a misleading stack |
532 |
|
|
* trace. |
533 |
dl |
1.45 |
* |
534 |
|
|
* @return the exception, or null if none |
535 |
|
|
*/ |
536 |
|
|
private Throwable getThrowableException() { |
537 |
dl |
1.124 |
Throwable ex; Aux a; |
538 |
|
|
if ((a = aux) == null) |
539 |
|
|
ex = null; |
540 |
|
|
else if ((ex = a.ex) != null && a.thread != Thread.currentThread()) { |
541 |
dl |
1.45 |
try { |
542 |
dl |
1.124 |
Constructor<?> noArgCtor = null, oneArgCtor = null; |
543 |
jsr166 |
1.106 |
for (Constructor<?> c : ex.getClass().getConstructors()) { |
544 |
dl |
1.45 |
Class<?>[] ps = c.getParameterTypes(); |
545 |
|
|
if (ps.length == 0) |
546 |
|
|
noArgCtor = c; |
547 |
dl |
1.124 |
else if (ps.length == 1 && ps[0] == Throwable.class) { |
548 |
|
|
oneArgCtor = c; |
549 |
|
|
break; |
550 |
|
|
} |
551 |
dl |
1.45 |
} |
552 |
dl |
1.124 |
if (oneArgCtor != null) |
553 |
|
|
ex = (Throwable)oneArgCtor.newInstance(ex); |
554 |
|
|
else if (noArgCtor != null) { |
555 |
|
|
Throwable rx = (Throwable)noArgCtor.newInstance(); |
556 |
|
|
rx.initCause(ex); |
557 |
|
|
ex = rx; |
558 |
dl |
1.45 |
} |
559 |
|
|
} catch (Exception ignore) { |
560 |
|
|
} |
561 |
|
|
} |
562 |
|
|
return ex; |
563 |
|
|
} |
564 |
|
|
|
565 |
|
|
/** |
566 |
dl |
1.128 |
* Returns exception associated with the given status, or null if none. |
567 |
|
|
*/ |
568 |
|
|
private Throwable getException(int s) { |
569 |
|
|
Throwable ex = null; |
570 |
|
|
if ((s & ABNORMAL) != 0 && |
571 |
|
|
((s & THROWN) == 0 || (ex = getThrowableException()) == null)) |
572 |
|
|
ex = new CancellationException(); |
573 |
|
|
return ex; |
574 |
|
|
} |
575 |
|
|
|
576 |
|
|
/** |
577 |
dl |
1.124 |
* Throws exception associated with the given status, or |
578 |
|
|
* CancellationException if none recorded. |
579 |
dl |
1.45 |
*/ |
580 |
dl |
1.124 |
private void reportException(int s) { |
581 |
|
|
ForkJoinTask.<RuntimeException>uncheckedThrow( |
582 |
|
|
(s & THROWN) != 0 ? getThrowableException() : null); |
583 |
dl |
1.45 |
} |
584 |
|
|
|
585 |
|
|
/** |
586 |
dl |
1.124 |
* A version of "sneaky throw" to relay exceptions in other |
587 |
|
|
* contexts. |
588 |
dl |
1.65 |
*/ |
589 |
jsr166 |
1.78 |
static void rethrow(Throwable ex) { |
590 |
dl |
1.100 |
ForkJoinTask.<RuntimeException>uncheckedThrow(ex); |
591 |
dl |
1.65 |
} |
592 |
|
|
|
593 |
|
|
/** |
594 |
|
|
* The sneaky part of sneaky throw, relying on generics |
595 |
|
|
* limitations to evade compiler complaints about rethrowing |
596 |
dl |
1.124 |
* unchecked exceptions. If argument null, throws |
597 |
|
|
* CancellationException. |
598 |
dl |
1.65 |
*/ |
599 |
|
|
@SuppressWarnings("unchecked") static <T extends Throwable> |
600 |
dl |
1.100 |
void uncheckedThrow(Throwable t) throws T { |
601 |
dl |
1.124 |
if (t == null) |
602 |
|
|
t = new CancellationException(); |
603 |
|
|
throw (T)t; // rely on vacuous cast |
604 |
jsr166 |
1.1 |
} |
605 |
|
|
|
606 |
|
|
// public methods |
607 |
|
|
|
608 |
|
|
/** |
609 |
dl |
1.64 |
* Arranges to asynchronously execute this task in the pool the |
610 |
|
|
* current task is running in, if applicable, or using the {@link |
611 |
dl |
1.67 |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
612 |
dl |
1.64 |
* it is not necessarily enforced, it is a usage error to fork a |
613 |
|
|
* task more than once unless it has completed and been |
614 |
|
|
* reinitialized. Subsequent modifications to the state of this |
615 |
|
|
* task or any data it operates on are not necessarily |
616 |
|
|
* consistently observable by any thread other than the one |
617 |
|
|
* executing it unless preceded by a call to {@link #join} or |
618 |
|
|
* related methods, or a call to {@link #isDone} returning {@code |
619 |
|
|
* true}. |
620 |
jsr166 |
1.2 |
* |
621 |
jsr166 |
1.6 |
* @return {@code this}, to simplify usage |
622 |
jsr166 |
1.1 |
*/ |
623 |
jsr166 |
1.2 |
public final ForkJoinTask<V> fork() { |
624 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread w; |
625 |
dl |
1.64 |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
626 |
dl |
1.124 |
(w = (ForkJoinWorkerThread)t).workQueue.push(this, w.pool); |
627 |
dl |
1.64 |
else |
628 |
dl |
1.71 |
ForkJoinPool.common.externalPush(this); |
629 |
jsr166 |
1.2 |
return this; |
630 |
jsr166 |
1.1 |
} |
631 |
|
|
|
632 |
|
|
/** |
633 |
jsr166 |
1.115 |
* Returns the result of the computation when it |
634 |
|
|
* {@linkplain #isDone is done}. |
635 |
|
|
* This method differs from {@link #get()} in that abnormal |
636 |
|
|
* completion results in {@code RuntimeException} or {@code Error}, |
637 |
|
|
* not {@code ExecutionException}, and that interrupts of the |
638 |
|
|
* calling thread do <em>not</em> cause the method to abruptly |
639 |
|
|
* return by throwing {@code InterruptedException}. |
640 |
jsr166 |
1.1 |
* |
641 |
|
|
* @return the computed result |
642 |
|
|
*/ |
643 |
|
|
public final V join() { |
644 |
dl |
1.59 |
int s; |
645 |
dl |
1.124 |
if ((s = status) >= 0) |
646 |
dl |
1.128 |
s = awaitJoin(false); |
647 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
648 |
dl |
1.59 |
reportException(s); |
649 |
|
|
return getRawResult(); |
650 |
jsr166 |
1.1 |
} |
651 |
|
|
|
652 |
|
|
/** |
653 |
|
|
* Commences performing this task, awaits its completion if |
654 |
jsr166 |
1.21 |
* necessary, and returns its result, or throws an (unchecked) |
655 |
dl |
1.20 |
* {@code RuntimeException} or {@code Error} if the underlying |
656 |
|
|
* computation did so. |
657 |
jsr166 |
1.1 |
* |
658 |
|
|
* @return the computed result |
659 |
|
|
*/ |
660 |
|
|
public final V invoke() { |
661 |
dl |
1.59 |
int s; |
662 |
dl |
1.124 |
if ((s = doExec()) >= 0) |
663 |
dl |
1.128 |
s = awaitJoin(true); |
664 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
665 |
dl |
1.59 |
reportException(s); |
666 |
|
|
return getRawResult(); |
667 |
jsr166 |
1.1 |
} |
668 |
|
|
|
669 |
|
|
/** |
670 |
jsr166 |
1.8 |
* Forks the given tasks, returning when {@code isDone} holds for |
671 |
|
|
* each task or an (unchecked) exception is encountered, in which |
672 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
673 |
|
|
* encounters an exception, then this method throws any one of |
674 |
|
|
* these exceptions. If any task encounters an exception, the |
675 |
|
|
* other may be cancelled. However, the execution status of |
676 |
|
|
* individual tasks is not guaranteed upon exceptional return. The |
677 |
|
|
* status of each task may be obtained using {@link |
678 |
|
|
* #getException()} and related methods to check if they have been |
679 |
|
|
* cancelled, completed normally or exceptionally, or left |
680 |
|
|
* unprocessed. |
681 |
jsr166 |
1.6 |
* |
682 |
|
|
* @param t1 the first task |
683 |
|
|
* @param t2 the second task |
684 |
|
|
* @throws NullPointerException if any task is null |
685 |
jsr166 |
1.1 |
*/ |
686 |
jsr166 |
1.6 |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
687 |
dl |
1.59 |
int s1, s2; |
688 |
dl |
1.124 |
if (t1 == null || t2 == null) |
689 |
|
|
throw new NullPointerException(); |
690 |
jsr166 |
1.1 |
t2.fork(); |
691 |
dl |
1.124 |
if ((s1 = t1.doExec()) >= 0) |
692 |
dl |
1.128 |
s1 = t1.awaitJoin(true); |
693 |
|
|
if ((s1 & ABNORMAL) != 0) { |
694 |
|
|
cancelIgnoringExceptions(t2); |
695 |
dl |
1.59 |
t1.reportException(s1); |
696 |
dl |
1.128 |
} |
697 |
|
|
else { |
698 |
|
|
if ((s2 = t2.status) >= 0) |
699 |
|
|
s2 = t2.awaitJoin(false); |
700 |
|
|
if ((s2 & ABNORMAL) != 0) |
701 |
|
|
t2.reportException(s2); |
702 |
|
|
} |
703 |
jsr166 |
1.1 |
} |
704 |
|
|
|
705 |
|
|
/** |
706 |
jsr166 |
1.6 |
* Forks the given tasks, returning when {@code isDone} holds for |
707 |
jsr166 |
1.8 |
* each task or an (unchecked) exception is encountered, in which |
708 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
709 |
|
|
* encounters an exception, then this method throws any one of |
710 |
|
|
* these exceptions. If any task encounters an exception, others |
711 |
|
|
* may be cancelled. However, the execution status of individual |
712 |
|
|
* tasks is not guaranteed upon exceptional return. The status of |
713 |
|
|
* each task may be obtained using {@link #getException()} and |
714 |
|
|
* related methods to check if they have been cancelled, completed |
715 |
|
|
* normally or exceptionally, or left unprocessed. |
716 |
jsr166 |
1.6 |
* |
717 |
|
|
* @param tasks the tasks |
718 |
jsr166 |
1.8 |
* @throws NullPointerException if any task is null |
719 |
jsr166 |
1.1 |
*/ |
720 |
|
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
721 |
|
|
Throwable ex = null; |
722 |
|
|
int last = tasks.length - 1; |
723 |
dl |
1.124 |
for (int i = last, s; i >= 0; --i) { |
724 |
|
|
ForkJoinTask<?> t; |
725 |
|
|
if ((t = tasks[i]) == null) { |
726 |
|
|
ex = new NullPointerException(); |
727 |
|
|
break; |
728 |
jsr166 |
1.1 |
} |
729 |
dl |
1.124 |
if (i == 0) { |
730 |
|
|
if ((s = t.doExec()) >= 0) |
731 |
dl |
1.128 |
s = t.awaitJoin(true); |
732 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
733 |
dl |
1.128 |
ex = t.getException(s); |
734 |
dl |
1.124 |
break; |
735 |
jsr166 |
1.1 |
} |
736 |
dl |
1.124 |
t.fork(); |
737 |
jsr166 |
1.1 |
} |
738 |
dl |
1.124 |
if (ex == null) { |
739 |
|
|
for (int i = 1, s; i <= last; ++i) { |
740 |
|
|
ForkJoinTask<?> t; |
741 |
|
|
if ((t = tasks[i]) != null) { |
742 |
|
|
if ((s = t.status) >= 0) |
743 |
dl |
1.128 |
s = t.awaitJoin(false); |
744 |
|
|
if ((s & ABNORMAL) != 0 && (ex = t.getException(s)) != null) |
745 |
dl |
1.124 |
break; |
746 |
|
|
} |
747 |
|
|
} |
748 |
|
|
} |
749 |
dl |
1.128 |
if (ex != null) { |
750 |
|
|
for (int i = 1, s; i <= last; ++i) |
751 |
|
|
cancelIgnoringExceptions(tasks[i]); |
752 |
dl |
1.65 |
rethrow(ex); |
753 |
dl |
1.128 |
} |
754 |
jsr166 |
1.1 |
} |
755 |
|
|
|
756 |
|
|
/** |
757 |
jsr166 |
1.7 |
* Forks all tasks in the specified collection, returning when |
758 |
jsr166 |
1.8 |
* {@code isDone} holds for each task or an (unchecked) exception |
759 |
dl |
1.20 |
* is encountered, in which case the exception is rethrown. If |
760 |
|
|
* more than one task encounters an exception, then this method |
761 |
|
|
* throws any one of these exceptions. If any task encounters an |
762 |
|
|
* exception, others may be cancelled. However, the execution |
763 |
|
|
* status of individual tasks is not guaranteed upon exceptional |
764 |
|
|
* return. The status of each task may be obtained using {@link |
765 |
|
|
* #getException()} and related methods to check if they have been |
766 |
|
|
* cancelled, completed normally or exceptionally, or left |
767 |
|
|
* unprocessed. |
768 |
jsr166 |
1.6 |
* |
769 |
jsr166 |
1.1 |
* @param tasks the collection of tasks |
770 |
jsr166 |
1.82 |
* @param <T> the type of the values returned from the tasks |
771 |
jsr166 |
1.2 |
* @return the tasks argument, to simplify usage |
772 |
jsr166 |
1.1 |
* @throws NullPointerException if tasks or any element are null |
773 |
|
|
*/ |
774 |
jsr166 |
1.2 |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
775 |
jsr166 |
1.7 |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
776 |
jsr166 |
1.121 |
invokeAll(tasks.toArray(new ForkJoinTask<?>[0])); |
777 |
jsr166 |
1.2 |
return tasks; |
778 |
jsr166 |
1.1 |
} |
779 |
|
|
@SuppressWarnings("unchecked") |
780 |
|
|
List<? extends ForkJoinTask<?>> ts = |
781 |
|
|
(List<? extends ForkJoinTask<?>>) tasks; |
782 |
|
|
Throwable ex = null; |
783 |
dl |
1.124 |
int last = ts.size() - 1; // nearly same as array version |
784 |
|
|
for (int i = last, s; i >= 0; --i) { |
785 |
|
|
ForkJoinTask<?> t; |
786 |
|
|
if ((t = ts.get(i)) == null) { |
787 |
|
|
ex = new NullPointerException(); |
788 |
|
|
break; |
789 |
jsr166 |
1.1 |
} |
790 |
dl |
1.124 |
if (i == 0) { |
791 |
|
|
if ((s = t.doExec()) >= 0) |
792 |
dl |
1.128 |
s = t.awaitJoin(true); |
793 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
794 |
dl |
1.128 |
ex = t.getException(s); |
795 |
dl |
1.124 |
break; |
796 |
|
|
} |
797 |
|
|
t.fork(); |
798 |
|
|
} |
799 |
|
|
if (ex == null) { |
800 |
|
|
for (int i = 1, s; i <= last; ++i) { |
801 |
|
|
ForkJoinTask<?> t; |
802 |
|
|
if ((t = ts.get(i)) != null) { |
803 |
|
|
if ((s = t.status) >= 0) |
804 |
dl |
1.128 |
s = t.awaitJoin(false); |
805 |
|
|
if ((s & ABNORMAL) != 0 && (ex = t.getException(s)) != null) |
806 |
dl |
1.124 |
break; |
807 |
|
|
} |
808 |
jsr166 |
1.1 |
} |
809 |
|
|
} |
810 |
dl |
1.128 |
if (ex != null) { |
811 |
|
|
for (int i = 1, s; i <= last; ++i) |
812 |
|
|
cancelIgnoringExceptions(ts.get(i)); |
813 |
dl |
1.65 |
rethrow(ex); |
814 |
dl |
1.128 |
} |
815 |
jsr166 |
1.2 |
return tasks; |
816 |
jsr166 |
1.1 |
} |
817 |
|
|
|
818 |
|
|
/** |
819 |
jsr166 |
1.7 |
* Attempts to cancel execution of this task. This attempt will |
820 |
jsr166 |
1.36 |
* fail if the task has already completed or could not be |
821 |
|
|
* cancelled for some other reason. If successful, and this task |
822 |
|
|
* has not started when {@code cancel} is called, execution of |
823 |
dl |
1.38 |
* this task is suppressed. After this method returns |
824 |
|
|
* successfully, unless there is an intervening call to {@link |
825 |
|
|
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
826 |
|
|
* {@link #isDone}, and {@code cancel} will return {@code true} |
827 |
|
|
* and calls to {@link #join} and related methods will result in |
828 |
|
|
* {@code CancellationException}. |
829 |
jsr166 |
1.1 |
* |
830 |
|
|
* <p>This method may be overridden in subclasses, but if so, must |
831 |
dl |
1.38 |
* still ensure that these properties hold. In particular, the |
832 |
|
|
* {@code cancel} method itself must not throw exceptions. |
833 |
jsr166 |
1.1 |
* |
834 |
jsr166 |
1.6 |
* <p>This method is designed to be invoked by <em>other</em> |
835 |
jsr166 |
1.1 |
* tasks. To terminate the current task, you can just return or |
836 |
|
|
* throw an unchecked exception from its computation method, or |
837 |
jsr166 |
1.74 |
* invoke {@link #completeExceptionally(Throwable)}. |
838 |
jsr166 |
1.1 |
* |
839 |
dl |
1.38 |
* @param mayInterruptIfRunning this value has no effect in the |
840 |
|
|
* default implementation because interrupts are not used to |
841 |
|
|
* control cancellation. |
842 |
jsr166 |
1.1 |
* |
843 |
jsr166 |
1.4 |
* @return {@code true} if this task is now cancelled |
844 |
jsr166 |
1.1 |
*/ |
845 |
|
|
public boolean cancel(boolean mayInterruptIfRunning) { |
846 |
dl |
1.124 |
return (trySetCancelled() & (ABNORMAL | THROWN)) == ABNORMAL; |
847 |
jsr166 |
1.1 |
} |
848 |
|
|
|
849 |
jsr166 |
1.8 |
public final boolean isDone() { |
850 |
|
|
return status < 0; |
851 |
|
|
} |
852 |
|
|
|
853 |
|
|
public final boolean isCancelled() { |
854 |
dl |
1.118 |
return (status & (ABNORMAL | THROWN)) == ABNORMAL; |
855 |
jsr166 |
1.8 |
} |
856 |
|
|
|
857 |
|
|
/** |
858 |
jsr166 |
1.4 |
* Returns {@code true} if this task threw an exception or was cancelled. |
859 |
jsr166 |
1.1 |
* |
860 |
jsr166 |
1.4 |
* @return {@code true} if this task threw an exception or was cancelled |
861 |
jsr166 |
1.1 |
*/ |
862 |
|
|
public final boolean isCompletedAbnormally() { |
863 |
dl |
1.118 |
return (status & ABNORMAL) != 0; |
864 |
jsr166 |
1.1 |
} |
865 |
|
|
|
866 |
|
|
/** |
867 |
jsr166 |
1.8 |
* Returns {@code true} if this task completed without throwing an |
868 |
|
|
* exception and was not cancelled. |
869 |
|
|
* |
870 |
|
|
* @return {@code true} if this task completed without throwing an |
871 |
|
|
* exception and was not cancelled |
872 |
|
|
*/ |
873 |
|
|
public final boolean isCompletedNormally() { |
874 |
dl |
1.118 |
return (status & (DONE | ABNORMAL)) == DONE; |
875 |
jsr166 |
1.8 |
} |
876 |
|
|
|
877 |
|
|
/** |
878 |
jsr166 |
1.1 |
* Returns the exception thrown by the base computation, or a |
879 |
jsr166 |
1.6 |
* {@code CancellationException} if cancelled, or {@code null} if |
880 |
|
|
* none or if the method has not yet completed. |
881 |
jsr166 |
1.1 |
* |
882 |
jsr166 |
1.4 |
* @return the exception, or {@code null} if none |
883 |
jsr166 |
1.1 |
*/ |
884 |
|
|
public final Throwable getException() { |
885 |
dl |
1.128 |
return getException(status); |
886 |
jsr166 |
1.1 |
} |
887 |
|
|
|
888 |
|
|
/** |
889 |
|
|
* Completes this task abnormally, and if not already aborted or |
890 |
|
|
* cancelled, causes it to throw the given exception upon |
891 |
|
|
* {@code join} and related operations. This method may be used |
892 |
|
|
* to induce exceptions in asynchronous tasks, or to force |
893 |
|
|
* completion of tasks that would not otherwise complete. Its use |
894 |
jsr166 |
1.6 |
* in other situations is discouraged. This method is |
895 |
jsr166 |
1.1 |
* overridable, but overridden versions must invoke {@code super} |
896 |
|
|
* implementation to maintain guarantees. |
897 |
|
|
* |
898 |
jsr166 |
1.11 |
* @param ex the exception to throw. If this exception is not a |
899 |
|
|
* {@code RuntimeException} or {@code Error}, the actual exception |
900 |
|
|
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
901 |
jsr166 |
1.1 |
*/ |
902 |
|
|
public void completeExceptionally(Throwable ex) { |
903 |
dl |
1.124 |
trySetException((ex instanceof RuntimeException) || |
904 |
|
|
(ex instanceof Error) ? ex : |
905 |
|
|
new RuntimeException(ex)); |
906 |
jsr166 |
1.1 |
} |
907 |
|
|
|
908 |
|
|
/** |
909 |
|
|
* Completes this task, and if not already aborted or cancelled, |
910 |
dl |
1.22 |
* returning the given value as the result of subsequent |
911 |
|
|
* invocations of {@code join} and related operations. This method |
912 |
|
|
* may be used to provide results for asynchronous tasks, or to |
913 |
|
|
* provide alternative handling for tasks that would not otherwise |
914 |
|
|
* complete normally. Its use in other situations is |
915 |
|
|
* discouraged. This method is overridable, but overridden |
916 |
|
|
* versions must invoke {@code super} implementation to maintain |
917 |
|
|
* guarantees. |
918 |
jsr166 |
1.1 |
* |
919 |
|
|
* @param value the result value for this task |
920 |
|
|
*/ |
921 |
|
|
public void complete(V value) { |
922 |
|
|
try { |
923 |
|
|
setRawResult(value); |
924 |
|
|
} catch (Throwable rex) { |
925 |
dl |
1.124 |
trySetException(rex); |
926 |
jsr166 |
1.1 |
return; |
927 |
|
|
} |
928 |
dl |
1.118 |
setDone(); |
929 |
jsr166 |
1.1 |
} |
930 |
|
|
|
931 |
jsr166 |
1.25 |
/** |
932 |
dl |
1.62 |
* Completes this task normally without setting a value. The most |
933 |
|
|
* recent value established by {@link #setRawResult} (or {@code |
934 |
|
|
* null} by default) will be returned as the result of subsequent |
935 |
|
|
* invocations of {@code join} and related operations. |
936 |
|
|
* |
937 |
|
|
* @since 1.8 |
938 |
dl |
1.60 |
*/ |
939 |
|
|
public final void quietlyComplete() { |
940 |
dl |
1.118 |
setDone(); |
941 |
dl |
1.60 |
} |
942 |
|
|
|
943 |
|
|
/** |
944 |
dl |
1.29 |
* Waits if necessary for the computation to complete, and then |
945 |
|
|
* retrieves its result. |
946 |
|
|
* |
947 |
|
|
* @return the computed result |
948 |
|
|
* @throws CancellationException if the computation was cancelled |
949 |
|
|
* @throws ExecutionException if the computation threw an |
950 |
|
|
* exception |
951 |
|
|
* @throws InterruptedException if the current thread is not a |
952 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
953 |
jsr166 |
1.25 |
*/ |
954 |
jsr166 |
1.1 |
public final V get() throws InterruptedException, ExecutionException { |
955 |
dl |
1.128 |
int s; Throwable ex; |
956 |
|
|
if ((s = status) >= 0 && (s = awaitGet(false, 0L)) >= 0) |
957 |
dl |
1.124 |
throw new InterruptedException(); |
958 |
dl |
1.128 |
else if ((s & ABNORMAL) == 0) |
959 |
|
|
return getRawResult(); |
960 |
|
|
else if ((s & THROWN) == 0 || (ex = getThrowableException()) == null) |
961 |
dl |
1.45 |
throw new CancellationException(); |
962 |
dl |
1.118 |
else |
963 |
dl |
1.128 |
throw new ExecutionException(ex); |
964 |
jsr166 |
1.1 |
} |
965 |
dl |
1.14 |
|
966 |
jsr166 |
1.25 |
/** |
967 |
dl |
1.29 |
* Waits if necessary for at most the given time for the computation |
968 |
|
|
* to complete, and then retrieves its result, if available. |
969 |
|
|
* |
970 |
|
|
* @param timeout the maximum time to wait |
971 |
|
|
* @param unit the time unit of the timeout argument |
972 |
|
|
* @return the computed result |
973 |
|
|
* @throws CancellationException if the computation was cancelled |
974 |
|
|
* @throws ExecutionException if the computation threw an |
975 |
|
|
* exception |
976 |
|
|
* @throws InterruptedException if the current thread is not a |
977 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
978 |
|
|
* @throws TimeoutException if the wait timed out |
979 |
jsr166 |
1.25 |
*/ |
980 |
jsr166 |
1.1 |
public final V get(long timeout, TimeUnit unit) |
981 |
|
|
throws InterruptedException, ExecutionException, TimeoutException { |
982 |
dl |
1.128 |
int s; Throwable ex; |
983 |
dl |
1.124 |
long nanos = unit.toNanos(timeout); |
984 |
dl |
1.128 |
if ((s = status) >= 0 && (s = awaitGet(true, nanos)) >= 0) { |
985 |
|
|
if (s == ABNORMAL) |
986 |
|
|
throw new InterruptedException(); |
987 |
|
|
else |
988 |
|
|
throw new TimeoutException(); |
989 |
dl |
1.45 |
} |
990 |
dl |
1.128 |
else if ((s & ABNORMAL) == 0) |
991 |
|
|
return getRawResult(); |
992 |
|
|
else if ((s & THROWN) == 0 || (ex = getThrowableException()) == null) |
993 |
dl |
1.118 |
throw new CancellationException(); |
994 |
|
|
else |
995 |
dl |
1.128 |
throw new ExecutionException(ex); |
996 |
jsr166 |
1.1 |
} |
997 |
|
|
|
998 |
|
|
/** |
999 |
dl |
1.17 |
* Joins this task, without returning its result or throwing its |
1000 |
jsr166 |
1.1 |
* exception. This method may be useful when processing |
1001 |
|
|
* collections of tasks when some have been cancelled or otherwise |
1002 |
|
|
* known to have aborted. |
1003 |
|
|
*/ |
1004 |
|
|
public final void quietlyJoin() { |
1005 |
dl |
1.124 |
if (status >= 0) |
1006 |
dl |
1.128 |
awaitJoin(false); |
1007 |
jsr166 |
1.1 |
} |
1008 |
|
|
|
1009 |
|
|
/** |
1010 |
|
|
* Commences performing this task and awaits its completion if |
1011 |
dl |
1.17 |
* necessary, without returning its result or throwing its |
1012 |
dl |
1.22 |
* exception. |
1013 |
jsr166 |
1.1 |
*/ |
1014 |
|
|
public final void quietlyInvoke() { |
1015 |
dl |
1.124 |
if (doExec() >= 0) |
1016 |
dl |
1.128 |
awaitJoin(true); |
1017 |
jsr166 |
1.1 |
} |
1018 |
|
|
|
1019 |
|
|
/** |
1020 |
|
|
* Possibly executes tasks until the pool hosting the current task |
1021 |
jsr166 |
1.104 |
* {@linkplain ForkJoinPool#isQuiescent is quiescent}. This |
1022 |
|
|
* method may be of use in designs in which many tasks are forked, |
1023 |
|
|
* but none are explicitly joined, instead executing them until |
1024 |
|
|
* all are processed. |
1025 |
jsr166 |
1.1 |
*/ |
1026 |
|
|
public static void helpQuiesce() { |
1027 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread w; ForkJoinPool p; |
1028 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread && |
1029 |
|
|
(p = (w = (ForkJoinWorkerThread)t).pool) != null) |
1030 |
dl |
1.128 |
p.helpQuiescePool(w.workQueue, Long.MAX_VALUE, false); |
1031 |
dl |
1.64 |
else |
1032 |
dl |
1.128 |
ForkJoinPool.common.externalHelpQuiescePool(Long.MAX_VALUE, false); |
1033 |
jsr166 |
1.1 |
} |
1034 |
|
|
|
1035 |
|
|
/** |
1036 |
|
|
* Resets the internal bookkeeping state of this task, allowing a |
1037 |
|
|
* subsequent {@code fork}. This method allows repeated reuse of |
1038 |
|
|
* this task, but only if reuse occurs when this task has either |
1039 |
|
|
* never been forked, or has been forked, then completed and all |
1040 |
|
|
* outstanding joins of this task have also completed. Effects |
1041 |
jsr166 |
1.6 |
* under any other usage conditions are not guaranteed. |
1042 |
|
|
* This method may be useful when executing |
1043 |
jsr166 |
1.1 |
* pre-constructed trees of subtasks in loops. |
1044 |
jsr166 |
1.34 |
* |
1045 |
dl |
1.33 |
* <p>Upon completion of this method, {@code isDone()} reports |
1046 |
|
|
* {@code false}, and {@code getException()} reports {@code |
1047 |
|
|
* null}. However, the value returned by {@code getRawResult} is |
1048 |
|
|
* unaffected. To clear this value, you can invoke {@code |
1049 |
|
|
* setRawResult(null)}. |
1050 |
jsr166 |
1.1 |
*/ |
1051 |
|
|
public void reinitialize() { |
1052 |
dl |
1.124 |
aux = null; |
1053 |
|
|
status = 0; |
1054 |
jsr166 |
1.1 |
} |
1055 |
|
|
|
1056 |
|
|
/** |
1057 |
jsr166 |
1.103 |
* Returns the pool hosting the current thread, or {@code null} |
1058 |
|
|
* if the current thread is executing outside of any ForkJoinPool. |
1059 |
|
|
* |
1060 |
|
|
* <p>This method returns {@code null} if and only if {@link |
1061 |
|
|
* #inForkJoinPool} returns {@code false}. |
1062 |
jsr166 |
1.1 |
* |
1063 |
jsr166 |
1.97 |
* @return the pool, or {@code null} if none |
1064 |
jsr166 |
1.1 |
*/ |
1065 |
|
|
public static ForkJoinPool getPool() { |
1066 |
dl |
1.124 |
Thread t; |
1067 |
|
|
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1068 |
|
|
((ForkJoinWorkerThread) t).pool : null); |
1069 |
jsr166 |
1.1 |
} |
1070 |
|
|
|
1071 |
|
|
/** |
1072 |
dl |
1.42 |
* Returns {@code true} if the current thread is a {@link |
1073 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1074 |
jsr166 |
1.1 |
* |
1075 |
dl |
1.42 |
* @return {@code true} if the current thread is a {@link |
1076 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1077 |
|
|
* or {@code false} otherwise |
1078 |
jsr166 |
1.1 |
*/ |
1079 |
|
|
public static boolean inForkJoinPool() { |
1080 |
|
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1081 |
|
|
} |
1082 |
|
|
|
1083 |
|
|
/** |
1084 |
|
|
* Tries to unschedule this task for execution. This method will |
1085 |
dl |
1.64 |
* typically (but is not guaranteed to) succeed if this task is |
1086 |
|
|
* the most recently forked task by the current thread, and has |
1087 |
|
|
* not commenced executing in another thread. This method may be |
1088 |
|
|
* useful when arranging alternative local processing of tasks |
1089 |
|
|
* that could have been, but were not, stolen. |
1090 |
jsr166 |
1.1 |
* |
1091 |
jsr166 |
1.4 |
* @return {@code true} if unforked |
1092 |
jsr166 |
1.1 |
*/ |
1093 |
|
|
public boolean tryUnfork() { |
1094 |
dl |
1.126 |
Thread t; boolean owned; |
1095 |
|
|
ForkJoinPool.WorkQueue q = ((owned = (t = Thread.currentThread()) |
1096 |
|
|
instanceof ForkJoinWorkerThread) ? |
1097 |
|
|
((ForkJoinWorkerThread)t).workQueue : |
1098 |
|
|
ForkJoinPool.commonQueue()); |
1099 |
|
|
return q != null && q.tryUnpush(this, owned); |
1100 |
jsr166 |
1.1 |
} |
1101 |
|
|
|
1102 |
|
|
/** |
1103 |
|
|
* Returns an estimate of the number of tasks that have been |
1104 |
|
|
* forked by the current worker thread but not yet executed. This |
1105 |
|
|
* value may be useful for heuristic decisions about whether to |
1106 |
|
|
* fork other tasks. |
1107 |
|
|
* |
1108 |
|
|
* @return the number of tasks |
1109 |
|
|
*/ |
1110 |
|
|
public static int getQueuedTaskCount() { |
1111 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1112 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1113 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1114 |
|
|
else |
1115 |
dl |
1.124 |
q = ForkJoinPool.commonQueue(); |
1116 |
dl |
1.66 |
return (q == null) ? 0 : q.queueSize(); |
1117 |
jsr166 |
1.1 |
} |
1118 |
|
|
|
1119 |
|
|
/** |
1120 |
|
|
* Returns an estimate of how many more locally queued tasks are |
1121 |
|
|
* held by the current worker thread than there are other worker |
1122 |
dl |
1.64 |
* threads that might steal them, or zero if this thread is not |
1123 |
|
|
* operating in a ForkJoinPool. This value may be useful for |
1124 |
jsr166 |
1.1 |
* heuristic decisions about whether to fork other tasks. In many |
1125 |
|
|
* usages of ForkJoinTasks, at steady state, each worker should |
1126 |
|
|
* aim to maintain a small constant surplus (for example, 3) of |
1127 |
|
|
* tasks, and to process computations locally if this threshold is |
1128 |
|
|
* exceeded. |
1129 |
|
|
* |
1130 |
|
|
* @return the surplus number of tasks, which may be negative |
1131 |
|
|
*/ |
1132 |
|
|
public static int getSurplusQueuedTaskCount() { |
1133 |
dl |
1.66 |
return ForkJoinPool.getSurplusQueuedTaskCount(); |
1134 |
jsr166 |
1.1 |
} |
1135 |
|
|
|
1136 |
|
|
// Extension methods |
1137 |
|
|
|
1138 |
|
|
/** |
1139 |
jsr166 |
1.4 |
* Returns the result that would be returned by {@link #join}, even |
1140 |
|
|
* if this task completed abnormally, or {@code null} if this task |
1141 |
|
|
* is not known to have been completed. This method is designed |
1142 |
|
|
* to aid debugging, as well as to support extensions. Its use in |
1143 |
|
|
* any other context is discouraged. |
1144 |
jsr166 |
1.1 |
* |
1145 |
jsr166 |
1.4 |
* @return the result, or {@code null} if not completed |
1146 |
jsr166 |
1.1 |
*/ |
1147 |
|
|
public abstract V getRawResult(); |
1148 |
|
|
|
1149 |
|
|
/** |
1150 |
|
|
* Forces the given value to be returned as a result. This method |
1151 |
|
|
* is designed to support extensions, and should not in general be |
1152 |
|
|
* called otherwise. |
1153 |
|
|
* |
1154 |
|
|
* @param value the value |
1155 |
|
|
*/ |
1156 |
|
|
protected abstract void setRawResult(V value); |
1157 |
|
|
|
1158 |
|
|
/** |
1159 |
dl |
1.62 |
* Immediately performs the base action of this task and returns |
1160 |
|
|
* true if, upon return from this method, this task is guaranteed |
1161 |
dl |
1.122 |
* to have completed. This method may return false otherwise, to |
1162 |
|
|
* indicate that this task is not necessarily complete (or is not |
1163 |
|
|
* known to be complete), for example in asynchronous actions that |
1164 |
|
|
* require explicit invocations of completion methods. This method |
1165 |
|
|
* may also throw an (unchecked) exception to indicate abnormal |
1166 |
|
|
* exit. This method is designed to support extensions, and should |
1167 |
|
|
* not in general be called otherwise. |
1168 |
jsr166 |
1.1 |
* |
1169 |
dl |
1.62 |
* @return {@code true} if this task is known to have completed normally |
1170 |
jsr166 |
1.1 |
*/ |
1171 |
|
|
protected abstract boolean exec(); |
1172 |
|
|
|
1173 |
|
|
/** |
1174 |
jsr166 |
1.5 |
* Returns, but does not unschedule or execute, a task queued by |
1175 |
|
|
* the current thread but not yet executed, if one is immediately |
1176 |
dl |
1.66 |
* available. There is no guarantee that this task will actually |
1177 |
|
|
* be polled or executed next. Conversely, this method may return |
1178 |
|
|
* null even if a task exists but cannot be accessed without |
1179 |
|
|
* contention with other threads. This method is designed |
1180 |
jsr166 |
1.5 |
* primarily to support extensions, and is unlikely to be useful |
1181 |
jsr166 |
1.6 |
* otherwise. |
1182 |
|
|
* |
1183 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1184 |
jsr166 |
1.1 |
*/ |
1185 |
|
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1186 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1187 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1188 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1189 |
|
|
else |
1190 |
dl |
1.124 |
q = ForkJoinPool.commonQueue(); |
1191 |
dl |
1.66 |
return (q == null) ? null : q.peek(); |
1192 |
jsr166 |
1.1 |
} |
1193 |
|
|
|
1194 |
|
|
/** |
1195 |
|
|
* Unschedules and returns, without executing, the next task |
1196 |
dl |
1.64 |
* queued by the current thread but not yet executed, if the |
1197 |
|
|
* current thread is operating in a ForkJoinPool. This method is |
1198 |
|
|
* designed primarily to support extensions, and is unlikely to be |
1199 |
|
|
* useful otherwise. |
1200 |
jsr166 |
1.1 |
* |
1201 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1202 |
jsr166 |
1.1 |
*/ |
1203 |
|
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1204 |
dl |
1.64 |
Thread t; |
1205 |
dl |
1.124 |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1206 |
|
|
((ForkJoinWorkerThread)t).workQueue.nextLocalTask() : null); |
1207 |
jsr166 |
1.1 |
} |
1208 |
|
|
|
1209 |
|
|
/** |
1210 |
dl |
1.64 |
* If the current thread is operating in a ForkJoinPool, |
1211 |
|
|
* unschedules and returns, without executing, the next task |
1212 |
jsr166 |
1.1 |
* queued by the current thread but not yet executed, if one is |
1213 |
|
|
* available, or if not available, a task that was forked by some |
1214 |
|
|
* other thread, if available. Availability may be transient, so a |
1215 |
dl |
1.64 |
* {@code null} result does not necessarily imply quiescence of |
1216 |
|
|
* the pool this task is operating in. This method is designed |
1217 |
jsr166 |
1.1 |
* primarily to support extensions, and is unlikely to be useful |
1218 |
jsr166 |
1.6 |
* otherwise. |
1219 |
|
|
* |
1220 |
jsr166 |
1.4 |
* @return a task, or {@code null} if none are available |
1221 |
jsr166 |
1.1 |
*/ |
1222 |
|
|
protected static ForkJoinTask<?> pollTask() { |
1223 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread w; |
1224 |
|
|
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1225 |
|
|
(w = (ForkJoinWorkerThread)t).pool.nextTaskFor(w.workQueue) : |
1226 |
|
|
null); |
1227 |
dl |
1.54 |
} |
1228 |
|
|
|
1229 |
dl |
1.94 |
/** |
1230 |
|
|
* If the current thread is operating in a ForkJoinPool, |
1231 |
|
|
* unschedules and returns, without executing, a task externally |
1232 |
|
|
* submitted to the pool, if one is available. Availability may be |
1233 |
|
|
* transient, so a {@code null} result does not necessarily imply |
1234 |
|
|
* quiescence of the pool. This method is designed primarily to |
1235 |
|
|
* support extensions, and is unlikely to be useful otherwise. |
1236 |
|
|
* |
1237 |
|
|
* @return a task, or {@code null} if none are available |
1238 |
jsr166 |
1.107 |
* @since 9 |
1239 |
dl |
1.94 |
*/ |
1240 |
|
|
protected static ForkJoinTask<?> pollSubmission() { |
1241 |
dl |
1.96 |
Thread t; |
1242 |
dl |
1.124 |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1243 |
|
|
((ForkJoinWorkerThread)t).pool.pollSubmission() : null); |
1244 |
dl |
1.94 |
} |
1245 |
|
|
|
1246 |
dl |
1.60 |
// tag operations |
1247 |
dl |
1.54 |
|
1248 |
|
|
/** |
1249 |
dl |
1.60 |
* Returns the tag for this task. |
1250 |
dl |
1.54 |
* |
1251 |
dl |
1.60 |
* @return the tag for this task |
1252 |
dl |
1.54 |
* @since 1.8 |
1253 |
|
|
*/ |
1254 |
dl |
1.60 |
public final short getForkJoinTaskTag() { |
1255 |
|
|
return (short)status; |
1256 |
dl |
1.54 |
} |
1257 |
|
|
|
1258 |
|
|
/** |
1259 |
jsr166 |
1.102 |
* Atomically sets the tag value for this task and returns the old value. |
1260 |
dl |
1.54 |
* |
1261 |
jsr166 |
1.102 |
* @param newValue the new tag value |
1262 |
dl |
1.60 |
* @return the previous value of the tag |
1263 |
dl |
1.54 |
* @since 1.8 |
1264 |
|
|
*/ |
1265 |
jsr166 |
1.102 |
public final short setForkJoinTaskTag(short newValue) { |
1266 |
dl |
1.54 |
for (int s;;) { |
1267 |
dl |
1.124 |
if (casStatus(s = status, (s & ~SMASK) | (newValue & SMASK))) |
1268 |
dl |
1.60 |
return (short)s; |
1269 |
dl |
1.54 |
} |
1270 |
|
|
} |
1271 |
|
|
|
1272 |
|
|
/** |
1273 |
dl |
1.60 |
* Atomically conditionally sets the tag value for this task. |
1274 |
|
|
* Among other applications, tags can be used as visit markers |
1275 |
dl |
1.61 |
* in tasks operating on graphs, as in methods that check: {@code |
1276 |
dl |
1.60 |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
1277 |
|
|
* before processing, otherwise exiting because the node has |
1278 |
|
|
* already been visited. |
1279 |
dl |
1.54 |
* |
1280 |
jsr166 |
1.102 |
* @param expect the expected tag value |
1281 |
|
|
* @param update the new tag value |
1282 |
jsr166 |
1.76 |
* @return {@code true} if successful; i.e., the current value was |
1283 |
jsr166 |
1.102 |
* equal to {@code expect} and was changed to {@code update}. |
1284 |
dl |
1.54 |
* @since 1.8 |
1285 |
|
|
*/ |
1286 |
jsr166 |
1.102 |
public final boolean compareAndSetForkJoinTaskTag(short expect, short update) { |
1287 |
dl |
1.54 |
for (int s;;) { |
1288 |
jsr166 |
1.102 |
if ((short)(s = status) != expect) |
1289 |
dl |
1.54 |
return false; |
1290 |
dl |
1.124 |
if (casStatus(s, (s & ~SMASK) | (update & SMASK))) |
1291 |
dl |
1.54 |
return true; |
1292 |
|
|
} |
1293 |
jsr166 |
1.1 |
} |
1294 |
|
|
|
1295 |
jsr166 |
1.5 |
/** |
1296 |
jsr166 |
1.95 |
* Adapter for Runnables. This implements RunnableFuture |
1297 |
jsr166 |
1.5 |
* to be compliant with AbstractExecutorService constraints |
1298 |
|
|
* when used in ForkJoinPool. |
1299 |
|
|
*/ |
1300 |
|
|
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1301 |
|
|
implements RunnableFuture<T> { |
1302 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1303 |
jsr166 |
1.5 |
final Runnable runnable; |
1304 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1305 |
jsr166 |
1.5 |
T result; |
1306 |
|
|
AdaptedRunnable(Runnable runnable, T result) { |
1307 |
|
|
if (runnable == null) throw new NullPointerException(); |
1308 |
|
|
this.runnable = runnable; |
1309 |
dl |
1.59 |
this.result = result; // OK to set this even before completion |
1310 |
jsr166 |
1.5 |
} |
1311 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1312 |
|
|
public final void setRawResult(T v) { result = v; } |
1313 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1314 |
|
|
public final void run() { invoke(); } |
1315 |
jsr166 |
1.116 |
public String toString() { |
1316 |
|
|
return super.toString() + "[Wrapped task = " + runnable + "]"; |
1317 |
|
|
} |
1318 |
dl |
1.59 |
private static final long serialVersionUID = 5232453952276885070L; |
1319 |
|
|
} |
1320 |
|
|
|
1321 |
|
|
/** |
1322 |
jsr166 |
1.99 |
* Adapter for Runnables without results. |
1323 |
dl |
1.59 |
*/ |
1324 |
|
|
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
1325 |
|
|
implements RunnableFuture<Void> { |
1326 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1327 |
dl |
1.59 |
final Runnable runnable; |
1328 |
|
|
AdaptedRunnableAction(Runnable runnable) { |
1329 |
|
|
if (runnable == null) throw new NullPointerException(); |
1330 |
|
|
this.runnable = runnable; |
1331 |
jsr166 |
1.5 |
} |
1332 |
dl |
1.59 |
public final Void getRawResult() { return null; } |
1333 |
|
|
public final void setRawResult(Void v) { } |
1334 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1335 |
|
|
public final void run() { invoke(); } |
1336 |
jsr166 |
1.116 |
public String toString() { |
1337 |
|
|
return super.toString() + "[Wrapped task = " + runnable + "]"; |
1338 |
|
|
} |
1339 |
jsr166 |
1.5 |
private static final long serialVersionUID = 5232453952276885070L; |
1340 |
|
|
} |
1341 |
|
|
|
1342 |
|
|
/** |
1343 |
jsr166 |
1.99 |
* Adapter for Runnables in which failure forces worker exception. |
1344 |
dl |
1.73 |
*/ |
1345 |
|
|
static final class RunnableExecuteAction extends ForkJoinTask<Void> { |
1346 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1347 |
dl |
1.73 |
final Runnable runnable; |
1348 |
|
|
RunnableExecuteAction(Runnable runnable) { |
1349 |
|
|
if (runnable == null) throw new NullPointerException(); |
1350 |
|
|
this.runnable = runnable; |
1351 |
|
|
} |
1352 |
|
|
public final Void getRawResult() { return null; } |
1353 |
|
|
public final void setRawResult(Void v) { } |
1354 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1355 |
dl |
1.124 |
int trySetException(Throwable ex) { |
1356 |
dl |
1.126 |
int s; // if runnable has a handler, invoke it |
1357 |
|
|
if (isExceptionalStatus(s = trySetThrown(ex)) && |
1358 |
|
|
runnable instanceof java.lang.Thread.UncaughtExceptionHandler) { |
1359 |
|
|
try { |
1360 |
|
|
((java.lang.Thread.UncaughtExceptionHandler)runnable). |
1361 |
|
|
uncaughtException(Thread.currentThread(), ex); |
1362 |
|
|
} catch (Throwable ignore) { |
1363 |
|
|
} |
1364 |
|
|
} |
1365 |
dl |
1.124 |
return s; |
1366 |
dl |
1.73 |
} |
1367 |
|
|
private static final long serialVersionUID = 5232453952276885070L; |
1368 |
|
|
} |
1369 |
|
|
|
1370 |
|
|
/** |
1371 |
jsr166 |
1.99 |
* Adapter for Callables. |
1372 |
jsr166 |
1.5 |
*/ |
1373 |
|
|
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1374 |
|
|
implements RunnableFuture<T> { |
1375 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1376 |
jsr166 |
1.6 |
final Callable<? extends T> callable; |
1377 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1378 |
jsr166 |
1.5 |
T result; |
1379 |
jsr166 |
1.6 |
AdaptedCallable(Callable<? extends T> callable) { |
1380 |
jsr166 |
1.5 |
if (callable == null) throw new NullPointerException(); |
1381 |
|
|
this.callable = callable; |
1382 |
|
|
} |
1383 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1384 |
|
|
public final void setRawResult(T v) { result = v; } |
1385 |
|
|
public final boolean exec() { |
1386 |
jsr166 |
1.5 |
try { |
1387 |
|
|
result = callable.call(); |
1388 |
|
|
return true; |
1389 |
|
|
} catch (RuntimeException rex) { |
1390 |
|
|
throw rex; |
1391 |
|
|
} catch (Exception ex) { |
1392 |
|
|
throw new RuntimeException(ex); |
1393 |
|
|
} |
1394 |
|
|
} |
1395 |
dl |
1.59 |
public final void run() { invoke(); } |
1396 |
jsr166 |
1.116 |
public String toString() { |
1397 |
|
|
return super.toString() + "[Wrapped task = " + callable + "]"; |
1398 |
|
|
} |
1399 |
jsr166 |
1.117 |
private static final long serialVersionUID = 2838392045355241008L; |
1400 |
jsr166 |
1.5 |
} |
1401 |
jsr166 |
1.2 |
|
1402 |
|
|
/** |
1403 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1404 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1405 |
|
|
* a null result upon {@link #join}. |
1406 |
jsr166 |
1.2 |
* |
1407 |
|
|
* @param runnable the runnable action |
1408 |
|
|
* @return the task |
1409 |
|
|
*/ |
1410 |
jsr166 |
1.6 |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1411 |
dl |
1.59 |
return new AdaptedRunnableAction(runnable); |
1412 |
jsr166 |
1.2 |
} |
1413 |
|
|
|
1414 |
|
|
/** |
1415 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1416 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1417 |
|
|
* the given result upon {@link #join}. |
1418 |
jsr166 |
1.2 |
* |
1419 |
|
|
* @param runnable the runnable action |
1420 |
|
|
* @param result the result upon completion |
1421 |
jsr166 |
1.82 |
* @param <T> the type of the result |
1422 |
jsr166 |
1.2 |
* @return the task |
1423 |
|
|
*/ |
1424 |
|
|
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1425 |
jsr166 |
1.5 |
return new AdaptedRunnable<T>(runnable, result); |
1426 |
jsr166 |
1.2 |
} |
1427 |
|
|
|
1428 |
|
|
/** |
1429 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1430 |
|
|
* method of the given {@code Callable} as its action, and returns |
1431 |
|
|
* its result upon {@link #join}, translating any checked exceptions |
1432 |
|
|
* encountered into {@code RuntimeException}. |
1433 |
jsr166 |
1.2 |
* |
1434 |
|
|
* @param callable the callable action |
1435 |
jsr166 |
1.82 |
* @param <T> the type of the callable's result |
1436 |
jsr166 |
1.2 |
* @return the task |
1437 |
|
|
*/ |
1438 |
jsr166 |
1.6 |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1439 |
jsr166 |
1.5 |
return new AdaptedCallable<T>(callable); |
1440 |
jsr166 |
1.2 |
} |
1441 |
|
|
|
1442 |
jsr166 |
1.1 |
// Serialization support |
1443 |
|
|
|
1444 |
|
|
private static final long serialVersionUID = -7721805057305804111L; |
1445 |
|
|
|
1446 |
|
|
/** |
1447 |
jsr166 |
1.53 |
* Saves this task to a stream (that is, serializes it). |
1448 |
jsr166 |
1.1 |
* |
1449 |
jsr166 |
1.83 |
* @param s the stream |
1450 |
jsr166 |
1.84 |
* @throws java.io.IOException if an I/O error occurs |
1451 |
jsr166 |
1.1 |
* @serialData the current run status and the exception thrown |
1452 |
jsr166 |
1.4 |
* during execution, or {@code null} if none |
1453 |
jsr166 |
1.1 |
*/ |
1454 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1455 |
|
|
throws java.io.IOException { |
1456 |
dl |
1.124 |
Aux a; |
1457 |
jsr166 |
1.1 |
s.defaultWriteObject(); |
1458 |
dl |
1.124 |
s.writeObject((a = aux) == null ? null : a.ex); |
1459 |
jsr166 |
1.1 |
} |
1460 |
|
|
|
1461 |
|
|
/** |
1462 |
jsr166 |
1.53 |
* Reconstitutes this task from a stream (that is, deserializes it). |
1463 |
jsr166 |
1.83 |
* @param s the stream |
1464 |
jsr166 |
1.84 |
* @throws ClassNotFoundException if the class of a serialized object |
1465 |
|
|
* could not be found |
1466 |
|
|
* @throws java.io.IOException if an I/O error occurs |
1467 |
jsr166 |
1.1 |
*/ |
1468 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1469 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1470 |
|
|
s.defaultReadObject(); |
1471 |
|
|
Object ex = s.readObject(); |
1472 |
|
|
if (ex != null) |
1473 |
dl |
1.124 |
trySetThrown((Throwable)ex); |
1474 |
jsr166 |
1.1 |
} |
1475 |
|
|
|
1476 |
dl |
1.45 |
static { |
1477 |
jsr166 |
1.1 |
try { |
1478 |
dl |
1.109 |
MethodHandles.Lookup l = MethodHandles.lookup(); |
1479 |
|
|
STATUS = l.findVarHandle(ForkJoinTask.class, "status", int.class); |
1480 |
dl |
1.124 |
AUX = l.findVarHandle(ForkJoinTask.class, "aux", Aux.class); |
1481 |
jsr166 |
1.91 |
} catch (ReflectiveOperationException e) { |
1482 |
jsr166 |
1.120 |
throw new ExceptionInInitializerError(e); |
1483 |
jsr166 |
1.1 |
} |
1484 |
|
|
} |
1485 |
dl |
1.45 |
|
1486 |
jsr166 |
1.1 |
} |