5 |
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*/ |
6 |
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|
7 |
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package jsr166y; |
8 |
< |
import java.util.*; |
8 |
> |
|
9 |
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import java.util.concurrent.*; |
10 |
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import java.util.concurrent.locks.*; |
11 |
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import java.util.concurrent.atomic.*; |
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import sun.misc.Unsafe; |
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import java.lang.reflect.*; |
10 |
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|
11 |
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import java.util.ArrayList; |
12 |
> |
import java.util.Arrays; |
13 |
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import java.util.Collection; |
14 |
> |
import java.util.Collections; |
15 |
> |
import java.util.List; |
16 |
> |
import java.util.concurrent.locks.Condition; |
17 |
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import java.util.concurrent.locks.LockSupport; |
18 |
> |
import java.util.concurrent.locks.ReentrantLock; |
19 |
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import java.util.concurrent.atomic.AtomicInteger; |
20 |
> |
import java.util.concurrent.atomic.AtomicLong; |
21 |
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|
22 |
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/** |
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* An {@link ExecutorService} for running {@link ForkJoinTask}s. A |
24 |
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* ForkJoinPool provides the entry point for submissions from |
25 |
< |
* non-ForkJoinTasks, as well as management and monitoring operations. |
26 |
< |
* Normally a single ForkJoinPool is used for a large number of |
20 |
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* submitted tasks. Otherwise, use would not usually outweigh the |
21 |
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* construction and bookkeeping overhead of creating a large set of |
22 |
< |
* threads. |
23 |
> |
* An {@link ExecutorService} for running {@link ForkJoinTask}s. |
24 |
> |
* A {@code ForkJoinPool} provides the entry point for submissions |
25 |
> |
* from non-{@code ForkJoinTask}s, as well as management and |
26 |
> |
* monitoring operations. |
27 |
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* |
28 |
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* <p>ForkJoinPools differ from other kinds of Executors mainly in |
29 |
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* that they provide <em>work-stealing</em>: all threads in the pool |
30 |
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* attempt to find and execute subtasks created by other active tasks |
31 |
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* (eventually blocking if none exist). This makes them efficient when |
32 |
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* most tasks spawn other subtasks (as do most ForkJoinTasks), as well |
33 |
< |
* as the mixed execution of some plain Runnable- or Callable- based |
34 |
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* activities along with ForkJoinTasks. When setting |
35 |
< |
* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for |
36 |
< |
* use with fine-grained tasks that are never joined. Otherwise, other |
37 |
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* ExecutorService implementations are typically more appropriate |
38 |
< |
* choices. |
28 |
> |
* <p>A {@code ForkJoinPool} differs from other kinds of {@link |
29 |
> |
* ExecutorService} mainly by virtue of employing |
30 |
> |
* <em>work-stealing</em>: all threads in the pool attempt to find and |
31 |
> |
* execute subtasks created by other active tasks (eventually blocking |
32 |
> |
* waiting for work if none exist). This enables efficient processing |
33 |
> |
* when most tasks spawn other subtasks (as do most {@code |
34 |
> |
* ForkJoinTask}s). A {@code ForkJoinPool} may also be used for mixed |
35 |
> |
* execution of some plain {@code Runnable}- or {@code Callable}- |
36 |
> |
* based activities along with {@code ForkJoinTask}s. When setting |
37 |
> |
* {@linkplain #setAsyncMode async mode}, a {@code ForkJoinPool} may |
38 |
> |
* also be appropriate for use with fine-grained tasks of any form |
39 |
> |
* that are never joined. Otherwise, other {@code ExecutorService} |
40 |
> |
* implementations are typically more appropriate choices. |
41 |
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* |
42 |
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* <p>A ForkJoinPool may be constructed with a given parallelism level |
43 |
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* (target pool size), which it attempts to maintain by dynamically |
44 |
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* adding, suspending, or resuming threads, even if some tasks are |
45 |
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* waiting to join others. However, no such adjustments are performed |
46 |
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* in the face of blocked IO or other unmanaged synchronization. The |
47 |
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* nested {@code ManagedBlocker} interface enables extension of |
48 |
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* the kinds of synchronization accommodated. The target parallelism |
49 |
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* level may also be changed dynamically ({@code setParallelism}) |
50 |
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* and thread construction can be limited using methods |
51 |
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* {@code setMaximumPoolSize} and/or |
52 |
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* {@code setMaintainsParallelism}. |
42 |
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* <p>A {@code ForkJoinPool} is constructed with a given target |
43 |
> |
* parallelism level; by default, equal to the number of available |
44 |
> |
* processors. Unless configured otherwise via {@link |
45 |
> |
* #setMaintainsParallelism}, the pool attempts to maintain this |
46 |
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* number of active (or available) threads by dynamically adding, |
47 |
> |
* suspending, or resuming internal worker threads, even if some tasks |
48 |
> |
* are stalled waiting to join others. However, no such adjustments |
49 |
> |
* are performed in the face of blocked IO or other unmanaged |
50 |
> |
* synchronization. The nested {@link ManagedBlocker} interface |
51 |
> |
* enables extension of the kinds of synchronization accommodated. |
52 |
> |
* The target parallelism level may also be changed dynamically |
53 |
> |
* ({@link #setParallelism}). The total number of threads may be |
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* limited using method {@link #setMaximumPoolSize}, in which case it |
55 |
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* may become possible for the activities of a pool to stall due to |
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* the lack of available threads to process new tasks. |
57 |
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* |
58 |
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* <p>In addition to execution and lifecycle control methods, this |
59 |
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* class provides status check methods (for example |
60 |
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* {@code getStealCount}) that are intended to aid in developing, |
60 |
> |
* {@link #getStealCount}) that are intended to aid in developing, |
61 |
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* tuning, and monitoring fork/join applications. Also, method |
62 |
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* {@code toString} returns indications of pool state in a |
62 |
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* {@link #toString} returns indications of pool state in a |
63 |
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* convenient form for informal monitoring. |
64 |
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* |
65 |
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* <p><b>Sample Usage.</b> Normally a single {@code ForkJoinPool} is |
66 |
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* used for all parallel task execution in a program or subsystem. |
67 |
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* Otherwise, use would not usually outweigh the construction and |
68 |
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* bookkeeping overhead of creating a large set of threads. For |
69 |
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* example, a common pool could be used for the {@code SortTasks} |
70 |
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* illustrated in {@link RecursiveAction}. Because {@code |
71 |
+ |
* ForkJoinPool} uses threads in {@linkplain java.lang.Thread#isDaemon |
72 |
+ |
* daemon} mode, there is typically no need to explicitly {@link |
73 |
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* #shutdown} such a pool upon program exit. |
74 |
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* |
75 |
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* <pre> |
76 |
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* static final ForkJoinPool mainPool = new ForkJoinPool(); |
77 |
+ |
* ... |
78 |
+ |
* public void sort(long[] array) { |
79 |
+ |
* mainPool.invoke(new SortTask(array, 0, array.length)); |
80 |
+ |
* } |
81 |
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* </pre> |
82 |
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* |
83 |
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* <p><b>Implementation notes</b>: This implementation restricts the |
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* maximum number of running threads to 32767. Attempts to create |
85 |
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* pools with greater than the maximum result in |
86 |
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* IllegalArgumentExceptions. |
86 |
> |
* {@code IllegalArgumentException}. |
87 |
> |
* |
88 |
> |
* @since 1.7 |
89 |
> |
* @author Doug Lea |
90 |
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*/ |
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public class ForkJoinPool extends AbstractExecutorService { |
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|
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private static final int MAX_THREADS = 0x7FFF; |
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|
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/** |
105 |
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* Factory for creating new ForkJoinWorkerThreads. A |
106 |
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* ForkJoinWorkerThreadFactory must be defined and used for |
107 |
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* ForkJoinWorkerThread subclasses that extend base functionality |
108 |
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* or initialize threads with different contexts. |
105 |
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* Factory for creating new {@link ForkJoinWorkerThread}s. |
106 |
> |
* A {@code ForkJoinWorkerThreadFactory} must be defined and used |
107 |
> |
* for {@code ForkJoinWorkerThread} subclasses that extend base |
108 |
> |
* functionality or initialize threads with different contexts. |
109 |
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*/ |
110 |
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public static interface ForkJoinWorkerThreadFactory { |
111 |
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/** |
112 |
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* Returns a new worker thread operating in the given pool. |
113 |
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* |
114 |
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* @param pool the pool this thread works in |
115 |
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* @throws NullPointerException if pool is null; |
115 |
> |
* @throws NullPointerException if pool is null |
116 |
|
*/ |
117 |
|
public ForkJoinWorkerThread newThread(ForkJoinPool pool); |
118 |
|
} |
119 |
|
|
120 |
|
/** |
121 |
< |
* Default ForkJoinWorkerThreadFactory implementation, creates a |
121 |
> |
* Default ForkJoinWorkerThreadFactory implementation; creates a |
122 |
|
* new ForkJoinWorkerThread. |
123 |
|
*/ |
124 |
|
static class DefaultForkJoinWorkerThreadFactory |
212 |
|
private final LinkedTransferQueue<ForkJoinTask<?>> submissionQueue; |
213 |
|
|
214 |
|
/** |
215 |
< |
* Head of Treiber stack for barrier sync. See below for explanation |
215 |
> |
* Head of Treiber stack for barrier sync. See below for explanation. |
216 |
|
*/ |
217 |
|
private volatile WaitQueueNode syncStack; |
218 |
|
|
247 |
|
* threads, packed into one int to ensure consistent snapshot when |
248 |
|
* making decisions about creating and suspending spare |
249 |
|
* threads. Updated only by CAS. Note: CASes in |
250 |
< |
* updateRunningCount and preJoin running active count is in low |
251 |
< |
* word, so need to be modified if this changes |
250 |
> |
* updateRunningCount and preJoin assume that running active count |
251 |
> |
* is in low word, so need to be modified if this changes. |
252 |
|
*/ |
253 |
|
private volatile int workerCounts; |
254 |
|
|
260 |
|
* Adds delta (which may be negative) to running count. This must |
261 |
|
* be called before (with negative arg) and after (with positive) |
262 |
|
* any managed synchronization (i.e., mainly, joins). |
263 |
+ |
* |
264 |
|
* @param delta the number to add |
265 |
|
*/ |
266 |
|
final void updateRunningCount(int delta) { |
267 |
|
int s; |
268 |
< |
do;while (!casWorkerCounts(s = workerCounts, s + delta)); |
268 |
> |
do {} while (!casWorkerCounts(s = workerCounts, s + delta)); |
269 |
|
} |
270 |
|
|
271 |
|
/** |
272 |
|
* Adds delta (which may be negative) to both total and running |
273 |
|
* count. This must be called upon creation and termination of |
274 |
|
* worker threads. |
275 |
+ |
* |
276 |
|
* @param delta the number to add |
277 |
|
*/ |
278 |
|
private void updateWorkerCount(int delta) { |
279 |
|
int d = delta + (delta << 16); // add to both lo and hi parts |
280 |
|
int s; |
281 |
< |
do;while (!casWorkerCounts(s = workerCounts, s + d)); |
281 |
> |
do {} while (!casWorkerCounts(s = workerCounts, s + d)); |
282 |
|
} |
283 |
|
|
284 |
|
/** |
304 |
|
private static int runControlFor(int r, int a) { return (r << 16) + a; } |
305 |
|
|
306 |
|
/** |
307 |
< |
* Try incrementing active count; fail on contention. Called by |
308 |
< |
* workers before/during executing tasks. |
309 |
< |
* @return true on success; |
307 |
> |
* Tries incrementing active count; fails on contention. |
308 |
> |
* Called by workers before/during executing tasks. |
309 |
> |
* |
310 |
> |
* @return true on success |
311 |
|
*/ |
312 |
|
final boolean tryIncrementActiveCount() { |
313 |
|
int c = runControl; |
318 |
|
* Tries decrementing active count; fails on contention. |
319 |
|
* Possibly triggers termination on success. |
320 |
|
* Called by workers when they can't find tasks. |
321 |
+ |
* |
322 |
|
* @return true on success |
323 |
|
*/ |
324 |
|
final boolean tryDecrementActiveCount() { |
332 |
|
} |
333 |
|
|
334 |
|
/** |
335 |
< |
* Returns true if argument represents zero active count and |
336 |
< |
* nonzero runstate, which is the triggering condition for |
335 |
> |
* Returns {@code true} if argument represents zero active count |
336 |
> |
* and nonzero runstate, which is the triggering condition for |
337 |
|
* terminating on shutdown. |
338 |
|
*/ |
339 |
|
private static boolean canTerminateOnShutdown(int c) { |
340 |
< |
return ((c & -c) >>> 16) != 0; // i.e. least bit is nonzero runState bit |
340 |
> |
// i.e. least bit is nonzero runState bit |
341 |
> |
return ((c & -c) >>> 16) != 0; |
342 |
|
} |
343 |
|
|
344 |
|
/** |
363 |
|
// Constructors |
364 |
|
|
365 |
|
/** |
366 |
< |
* Creates a ForkJoinPool with a pool size equal to the number of |
367 |
< |
* processors available on the system and using the default |
368 |
< |
* ForkJoinWorkerThreadFactory, |
366 |
> |
* Creates a {@code ForkJoinPool} with parallelism equal to {@link |
367 |
> |
* java.lang.Runtime#availableProcessors}, and using the {@linkplain |
368 |
> |
* #defaultForkJoinWorkerThreadFactory default thread factory}. |
369 |
> |
* |
370 |
|
* @throws SecurityException if a security manager exists and |
371 |
|
* the caller is not permitted to modify threads |
372 |
|
* because it does not hold {@link |
373 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
373 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
374 |
|
*/ |
375 |
|
public ForkJoinPool() { |
376 |
|
this(Runtime.getRuntime().availableProcessors(), |
378 |
|
} |
379 |
|
|
380 |
|
/** |
381 |
< |
* Creates a ForkJoinPool with the indicated parallelism level |
382 |
< |
* threads, and using the default ForkJoinWorkerThreadFactory, |
383 |
< |
* @param parallelism the number of worker threads |
381 |
> |
* Creates a {@code ForkJoinPool} with the indicated parallelism |
382 |
> |
* level and using the {@linkplain |
383 |
> |
* #defaultForkJoinWorkerThreadFactory default thread factory}. |
384 |
> |
* |
385 |
> |
* @param parallelism the parallelism level |
386 |
|
* @throws IllegalArgumentException if parallelism less than or |
387 |
|
* equal to zero |
388 |
|
* @throws SecurityException if a security manager exists and |
389 |
|
* the caller is not permitted to modify threads |
390 |
|
* because it does not hold {@link |
391 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
391 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
392 |
|
*/ |
393 |
|
public ForkJoinPool(int parallelism) { |
394 |
|
this(parallelism, defaultForkJoinWorkerThreadFactory); |
395 |
|
} |
396 |
|
|
397 |
|
/** |
398 |
< |
* Creates a ForkJoinPool with parallelism equal to the number of |
399 |
< |
* processors available on the system and using the given |
400 |
< |
* ForkJoinWorkerThreadFactory, |
398 |
> |
* Creates a {@code ForkJoinPool} with parallelism equal to {@link |
399 |
> |
* java.lang.Runtime#availableProcessors}, and using the given |
400 |
> |
* thread factory. |
401 |
> |
* |
402 |
|
* @param factory the factory for creating new threads |
403 |
|
* @throws NullPointerException if factory is null |
404 |
|
* @throws SecurityException if a security manager exists and |
405 |
|
* the caller is not permitted to modify threads |
406 |
|
* because it does not hold {@link |
407 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
407 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
408 |
|
*/ |
409 |
|
public ForkJoinPool(ForkJoinWorkerThreadFactory factory) { |
410 |
|
this(Runtime.getRuntime().availableProcessors(), factory); |
411 |
|
} |
412 |
|
|
413 |
|
/** |
414 |
< |
* Creates a ForkJoinPool with the given parallelism and factory. |
414 |
> |
* Creates a {@code ForkJoinPool} with the given parallelism and |
415 |
> |
* thread factory. |
416 |
|
* |
417 |
< |
* @param parallelism the targeted number of worker threads |
417 |
> |
* @param parallelism the parallelism level |
418 |
|
* @param factory the factory for creating new threads |
419 |
|
* @throws IllegalArgumentException if parallelism less than or |
420 |
< |
* equal to zero, or greater than implementation limit. |
420 |
> |
* equal to zero, or greater than implementation limit |
421 |
|
* @throws NullPointerException if factory is null |
422 |
|
* @throws SecurityException if a security manager exists and |
423 |
|
* the caller is not permitted to modify threads |
424 |
|
* because it does not hold {@link |
425 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
425 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
426 |
|
*/ |
427 |
|
public ForkJoinPool(int parallelism, ForkJoinWorkerThreadFactory factory) { |
428 |
|
if (parallelism <= 0 || parallelism > MAX_THREADS) |
443 |
|
} |
444 |
|
|
445 |
|
/** |
446 |
< |
* Create new worker using factory. |
446 |
> |
* Creates a new worker thread using factory. |
447 |
> |
* |
448 |
|
* @param index the index to assign worker |
449 |
< |
* @return new worker, or null of factory failed |
449 |
> |
* @return new worker, or null if factory failed |
450 |
|
*/ |
451 |
|
private ForkJoinWorkerThread createWorker(int index) { |
452 |
|
Thread.UncaughtExceptionHandler h = ueh; |
466 |
|
* Returns a good size for worker array given pool size. |
467 |
|
* Currently requires size to be a power of two. |
468 |
|
*/ |
469 |
< |
private static int arraySizeFor(int ps) { |
470 |
< |
return ps <= 1? 1 : (1 << (32 - Integer.numberOfLeadingZeros(ps-1))); |
469 |
> |
private static int arraySizeFor(int poolSize) { |
470 |
> |
if (poolSize <= 1) |
471 |
> |
return 1; |
472 |
> |
// See Hackers Delight, sec 3.2 |
473 |
> |
int c = poolSize >= MAX_THREADS ? MAX_THREADS : (poolSize - 1); |
474 |
> |
c |= c >>> 1; |
475 |
> |
c |= c >>> 2; |
476 |
> |
c |= c >>> 4; |
477 |
> |
c |= c >>> 8; |
478 |
> |
c |= c >>> 16; |
479 |
> |
return c + 1; |
480 |
|
} |
481 |
|
|
482 |
|
/** |
483 |
|
* Creates or resizes array if necessary to hold newLength. |
484 |
< |
* Call only under exclusion or lock. |
484 |
> |
* Call only under exclusion. |
485 |
> |
* |
486 |
|
* @return the array |
487 |
|
*/ |
488 |
|
private ForkJoinWorkerThread[] ensureWorkerArrayCapacity(int newLength) { |
496 |
|
} |
497 |
|
|
498 |
|
/** |
499 |
< |
* Try to shrink workers into smaller array after one or more terminate |
499 |
> |
* Tries to shrink workers into smaller array after one or more terminate. |
500 |
|
*/ |
501 |
|
private void tryShrinkWorkerArray() { |
502 |
|
ForkJoinWorkerThread[] ws = workers; |
512 |
|
} |
513 |
|
|
514 |
|
/** |
515 |
< |
* Initialize workers if necessary |
515 |
> |
* Initializes workers if necessary. |
516 |
|
*/ |
517 |
|
final void ensureWorkerInitialization() { |
518 |
|
ForkJoinWorkerThread[] ws = workers; |
579 |
|
* Common code for execute, invoke and submit |
580 |
|
*/ |
581 |
|
private <T> void doSubmit(ForkJoinTask<T> task) { |
582 |
+ |
if (task == null) |
583 |
+ |
throw new NullPointerException(); |
584 |
|
if (isShutdown()) |
585 |
|
throw new RejectedExecutionException(); |
586 |
|
if (workers == null) |
590 |
|
} |
591 |
|
|
592 |
|
/** |
593 |
< |
* Performs the given task; returning its result upon completion |
593 |
> |
* Performs the given task, returning its result upon completion. |
594 |
> |
* |
595 |
|
* @param task the task |
596 |
|
* @return the task's result |
597 |
|
* @throws NullPointerException if task is null |
604 |
|
|
605 |
|
/** |
606 |
|
* Arranges for (asynchronous) execution of the given task. |
607 |
+ |
* |
608 |
|
* @param task the task |
609 |
|
* @throws NullPointerException if task is null |
610 |
|
* @throws RejectedExecutionException if pool is shut down |
611 |
|
*/ |
612 |
< |
public <T> void execute(ForkJoinTask<T> task) { |
612 |
> |
public void execute(ForkJoinTask<?> task) { |
613 |
|
doSubmit(task); |
614 |
|
} |
615 |
|
|
616 |
|
// AbstractExecutorService methods |
617 |
|
|
618 |
|
public void execute(Runnable task) { |
619 |
< |
doSubmit(new AdaptedRunnable<Void>(task, null)); |
619 |
> |
ForkJoinTask<?> job; |
620 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
621 |
> |
job = (ForkJoinTask<?>) task; |
622 |
> |
else |
623 |
> |
job = ForkJoinTask.adapt(task, null); |
624 |
> |
doSubmit(job); |
625 |
|
} |
626 |
|
|
627 |
|
public <T> ForkJoinTask<T> submit(Callable<T> task) { |
628 |
< |
ForkJoinTask<T> job = new AdaptedCallable<T>(task); |
628 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task); |
629 |
|
doSubmit(job); |
630 |
|
return job; |
631 |
|
} |
632 |
|
|
633 |
|
public <T> ForkJoinTask<T> submit(Runnable task, T result) { |
634 |
< |
ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result); |
634 |
> |
ForkJoinTask<T> job = ForkJoinTask.adapt(task, result); |
635 |
|
doSubmit(job); |
636 |
|
return job; |
637 |
|
} |
638 |
|
|
639 |
|
public ForkJoinTask<?> submit(Runnable task) { |
640 |
< |
ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null); |
640 |
> |
ForkJoinTask<?> job; |
641 |
> |
if (task instanceof ForkJoinTask<?>) // avoid re-wrap |
642 |
> |
job = (ForkJoinTask<?>) task; |
643 |
> |
else |
644 |
> |
job = ForkJoinTask.adapt(task, null); |
645 |
|
doSubmit(job); |
646 |
|
return job; |
647 |
|
} |
648 |
|
|
649 |
|
/** |
650 |
< |
* Adaptor for Runnables. This implements RunnableFuture |
651 |
< |
* to be compliant with AbstractExecutorService constraints |
650 |
> |
* Submits a ForkJoinTask for execution. |
651 |
> |
* |
652 |
> |
* @param task the task to submit |
653 |
> |
* @return the task |
654 |
> |
* @throws RejectedExecutionException if the task cannot be |
655 |
> |
* scheduled for execution |
656 |
> |
* @throws NullPointerException if the task is null |
657 |
|
*/ |
658 |
< |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
659 |
< |
implements RunnableFuture<T> { |
660 |
< |
final Runnable runnable; |
591 |
< |
final T resultOnCompletion; |
592 |
< |
T result; |
593 |
< |
AdaptedRunnable(Runnable runnable, T result) { |
594 |
< |
if (runnable == null) throw new NullPointerException(); |
595 |
< |
this.runnable = runnable; |
596 |
< |
this.resultOnCompletion = result; |
597 |
< |
} |
598 |
< |
public T getRawResult() { return result; } |
599 |
< |
public void setRawResult(T v) { result = v; } |
600 |
< |
public boolean exec() { |
601 |
< |
runnable.run(); |
602 |
< |
result = resultOnCompletion; |
603 |
< |
return true; |
604 |
< |
} |
605 |
< |
public void run() { invoke(); } |
658 |
> |
public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) { |
659 |
> |
doSubmit(task); |
660 |
> |
return task; |
661 |
|
} |
662 |
|
|
608 |
– |
/** |
609 |
– |
* Adaptor for Callables |
610 |
– |
*/ |
611 |
– |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
612 |
– |
implements RunnableFuture<T> { |
613 |
– |
final Callable<T> callable; |
614 |
– |
T result; |
615 |
– |
AdaptedCallable(Callable<T> callable) { |
616 |
– |
if (callable == null) throw new NullPointerException(); |
617 |
– |
this.callable = callable; |
618 |
– |
} |
619 |
– |
public T getRawResult() { return result; } |
620 |
– |
public void setRawResult(T v) { result = v; } |
621 |
– |
public boolean exec() { |
622 |
– |
try { |
623 |
– |
result = callable.call(); |
624 |
– |
return true; |
625 |
– |
} catch (Error err) { |
626 |
– |
throw err; |
627 |
– |
} catch (RuntimeException rex) { |
628 |
– |
throw rex; |
629 |
– |
} catch (Exception ex) { |
630 |
– |
throw new RuntimeException(ex); |
631 |
– |
} |
632 |
– |
} |
633 |
– |
public void run() { invoke(); } |
634 |
– |
} |
663 |
|
|
664 |
|
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) { |
665 |
< |
ArrayList<ForkJoinTask<T>> ts = |
665 |
> |
ArrayList<ForkJoinTask<T>> forkJoinTasks = |
666 |
|
new ArrayList<ForkJoinTask<T>>(tasks.size()); |
667 |
< |
for (Callable<T> c : tasks) |
668 |
< |
ts.add(new AdaptedCallable<T>(c)); |
669 |
< |
invoke(new InvokeAll<T>(ts)); |
670 |
< |
return (List<Future<T>>)(List)ts; |
667 |
> |
for (Callable<T> task : tasks) |
668 |
> |
forkJoinTasks.add(ForkJoinTask.adapt(task)); |
669 |
> |
invoke(new InvokeAll<T>(forkJoinTasks)); |
670 |
> |
|
671 |
> |
@SuppressWarnings({"unchecked", "rawtypes"}) |
672 |
> |
List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks; |
673 |
> |
return futures; |
674 |
|
} |
675 |
|
|
676 |
|
static final class InvokeAll<T> extends RecursiveAction { |
677 |
|
final ArrayList<ForkJoinTask<T>> tasks; |
678 |
|
InvokeAll(ArrayList<ForkJoinTask<T>> tasks) { this.tasks = tasks; } |
679 |
|
public void compute() { |
680 |
< |
try { invokeAll(tasks); } catch(Exception ignore) {} |
680 |
> |
try { invokeAll(tasks); } |
681 |
> |
catch (Exception ignore) {} |
682 |
|
} |
683 |
+ |
private static final long serialVersionUID = -7914297376763021607L; |
684 |
|
} |
685 |
|
|
686 |
|
// Configuration and status settings and queries |
687 |
|
|
688 |
|
/** |
689 |
< |
* Returns the factory used for constructing new workers |
689 |
> |
* Returns the factory used for constructing new workers. |
690 |
|
* |
691 |
|
* @return the factory used for constructing new workers |
692 |
|
*/ |
697 |
|
/** |
698 |
|
* Returns the handler for internal worker threads that terminate |
699 |
|
* due to unrecoverable errors encountered while executing tasks. |
700 |
< |
* @return the handler, or null if none |
700 |
> |
* |
701 |
> |
* @return the handler, or {@code null} if none |
702 |
|
*/ |
703 |
|
public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() { |
704 |
|
Thread.UncaughtExceptionHandler h; |
719 |
|
* as handler. |
720 |
|
* |
721 |
|
* @param h the new handler |
722 |
< |
* @return the old handler, or null if none |
722 |
> |
* @return the old handler, or {@code null} if none |
723 |
|
* @throws SecurityException if a security manager exists and |
724 |
|
* the caller is not permitted to modify threads |
725 |
|
* because it does not hold {@link |
726 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
726 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
727 |
|
*/ |
728 |
|
public Thread.UncaughtExceptionHandler |
729 |
|
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler h) { |
751 |
|
|
752 |
|
/** |
753 |
|
* Sets the target parallelism level of this pool. |
754 |
+ |
* |
755 |
|
* @param parallelism the target parallelism |
756 |
|
* @throws IllegalArgumentException if parallelism less than or |
757 |
< |
* equal to zero or greater than maximum size bounds. |
757 |
> |
* equal to zero or greater than maximum size bounds |
758 |
|
* @throws SecurityException if a security manager exists and |
759 |
|
* the caller is not permitted to modify threads |
760 |
|
* because it does not hold {@link |
761 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
761 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
762 |
|
*/ |
763 |
|
public void setParallelism(int parallelism) { |
764 |
|
checkPermission(); |
767 |
|
final ReentrantLock lock = this.workerLock; |
768 |
|
lock.lock(); |
769 |
|
try { |
770 |
< |
if (!isTerminating()) { |
770 |
> |
if (isProcessingTasks()) { |
771 |
|
int p = this.parallelism; |
772 |
|
this.parallelism = parallelism; |
773 |
|
if (parallelism > p) |
782 |
|
} |
783 |
|
|
784 |
|
/** |
785 |
< |
* Returns the targeted number of worker threads in this pool. |
785 |
> |
* Returns the targeted parallelism level of this pool. |
786 |
|
* |
787 |
< |
* @return the targeted number of worker threads in this pool |
787 |
> |
* @return the targeted parallelism level of this pool |
788 |
|
*/ |
789 |
|
public int getParallelism() { |
790 |
|
return parallelism; |
793 |
|
/** |
794 |
|
* Returns the number of worker threads that have started but not |
795 |
|
* yet terminated. This result returned by this method may differ |
796 |
< |
* from {@code getParallelism} when threads are created to |
796 |
> |
* from {@link #getParallelism} when threads are created to |
797 |
|
* maintain parallelism when others are cooperatively blocked. |
798 |
|
* |
799 |
|
* @return the number of worker threads |
804 |
|
|
805 |
|
/** |
806 |
|
* Returns the maximum number of threads allowed to exist in the |
807 |
< |
* pool, even if there are insufficient unblocked running threads. |
807 |
> |
* pool. Unless set using {@link #setMaximumPoolSize}, the |
808 |
> |
* maximum is an implementation-defined value designed only to |
809 |
> |
* prevent runaway growth. |
810 |
> |
* |
811 |
|
* @return the maximum |
812 |
|
*/ |
813 |
|
public int getMaximumPoolSize() { |
816 |
|
|
817 |
|
/** |
818 |
|
* Sets the maximum number of threads allowed to exist in the |
819 |
< |
* pool, even if there are insufficient unblocked running threads. |
820 |
< |
* Setting this value has no effect on current pool size. It |
821 |
< |
* controls construction of new threads. |
822 |
< |
* @throws IllegalArgumentException if negative or greater then |
823 |
< |
* internal implementation limit. |
819 |
> |
* pool. Setting this value has no effect on current pool |
820 |
> |
* size. It controls construction of new threads. |
821 |
> |
* |
822 |
> |
* @throws IllegalArgumentException if negative or greater than |
823 |
> |
* internal implementation limit |
824 |
|
*/ |
825 |
|
public void setMaximumPoolSize(int newMax) { |
826 |
|
if (newMax < 0 || newMax > MAX_THREADS) |
830 |
|
|
831 |
|
|
832 |
|
/** |
833 |
< |
* Returns true if this pool dynamically maintains its target |
834 |
< |
* parallelism level. If false, new threads are added only to |
835 |
< |
* avoid possible starvation. |
836 |
< |
* This setting is by default true; |
837 |
< |
* @return true if maintains parallelism |
833 |
> |
* Returns {@code true} if this pool dynamically maintains its |
834 |
> |
* target parallelism level. If false, new threads are added only |
835 |
> |
* to avoid possible starvation. This setting is by default true. |
836 |
> |
* |
837 |
> |
* @return {@code true} if maintains parallelism |
838 |
|
*/ |
839 |
|
public boolean getMaintainsParallelism() { |
840 |
|
return maintainsParallelism; |
844 |
|
* Sets whether this pool dynamically maintains its target |
845 |
|
* parallelism level. If false, new threads are added only to |
846 |
|
* avoid possible starvation. |
847 |
< |
* @param enable true to maintains parallelism |
847 |
> |
* |
848 |
> |
* @param enable {@code true} to maintain parallelism |
849 |
|
*/ |
850 |
|
public void setMaintainsParallelism(boolean enable) { |
851 |
|
maintainsParallelism = enable; |
856 |
|
* tasks that are never joined. This mode may be more appropriate |
857 |
|
* than default locally stack-based mode in applications in which |
858 |
|
* worker threads only process asynchronous tasks. This method is |
859 |
< |
* designed to be invoked only when pool is quiescent, and |
859 |
> |
* designed to be invoked only when the pool is quiescent, and |
860 |
|
* typically only before any tasks are submitted. The effects of |
861 |
|
* invocations at other times may be unpredictable. |
862 |
|
* |
863 |
< |
* @param async if true, use locally FIFO scheduling |
864 |
< |
* @return the previous mode. |
863 |
> |
* @param async if {@code true}, use locally FIFO scheduling |
864 |
> |
* @return the previous mode |
865 |
> |
* @see #getAsyncMode |
866 |
|
*/ |
867 |
|
public boolean setAsyncMode(boolean async) { |
868 |
|
boolean oldMode = locallyFifo; |
879 |
|
} |
880 |
|
|
881 |
|
/** |
882 |
< |
* Returns true if this pool uses local first-in-first-out |
882 |
> |
* Returns {@code true} if this pool uses local first-in-first-out |
883 |
|
* scheduling mode for forked tasks that are never joined. |
884 |
|
* |
885 |
< |
* @return true if this pool uses async mode. |
885 |
> |
* @return {@code true} if this pool uses async mode |
886 |
> |
* @see #setAsyncMode |
887 |
|
*/ |
888 |
|
public boolean getAsyncMode() { |
889 |
|
return locallyFifo; |
904 |
|
* Returns an estimate of the number of threads that are currently |
905 |
|
* stealing or executing tasks. This method may overestimate the |
906 |
|
* number of active threads. |
907 |
< |
* @return the number of active threads. |
907 |
> |
* |
908 |
> |
* @return the number of active threads |
909 |
|
*/ |
910 |
|
public int getActiveThreadCount() { |
911 |
|
return activeCountOf(runControl); |
915 |
|
* Returns an estimate of the number of threads that are currently |
916 |
|
* idle waiting for tasks. This method may underestimate the |
917 |
|
* number of idle threads. |
918 |
< |
* @return the number of idle threads. |
918 |
> |
* |
919 |
> |
* @return the number of idle threads |
920 |
|
*/ |
921 |
|
final int getIdleThreadCount() { |
922 |
|
int c = runningCountOf(workerCounts) - activeCountOf(runControl); |
923 |
< |
return (c <= 0)? 0 : c; |
923 |
> |
return (c <= 0) ? 0 : c; |
924 |
|
} |
925 |
|
|
926 |
|
/** |
927 |
< |
* Returns true if all worker threads are currently idle. An idle |
928 |
< |
* worker is one that cannot obtain a task to execute because none |
929 |
< |
* are available to steal from other threads, and there are no |
930 |
< |
* pending submissions to the pool. This method is conservative: |
931 |
< |
* It might not return true immediately upon idleness of all |
932 |
< |
* threads, but will eventually become true if threads remain |
933 |
< |
* inactive. |
934 |
< |
* @return true if all threads are currently idle |
927 |
> |
* Returns {@code true} if all worker threads are currently idle. |
928 |
> |
* An idle worker is one that cannot obtain a task to execute |
929 |
> |
* because none are available to steal from other threads, and |
930 |
> |
* there are no pending submissions to the pool. This method is |
931 |
> |
* conservative; it might not return {@code true} immediately upon |
932 |
> |
* idleness of all threads, but will eventually become true if |
933 |
> |
* threads remain inactive. |
934 |
> |
* |
935 |
> |
* @return {@code true} if all threads are currently idle |
936 |
|
*/ |
937 |
|
public boolean isQuiescent() { |
938 |
|
return activeCountOf(runControl) == 0; |
943 |
|
* one thread's work queue by another. The reported value |
944 |
|
* underestimates the actual total number of steals when the pool |
945 |
|
* is not quiescent. This value may be useful for monitoring and |
946 |
< |
* tuning fork/join programs: In general, steal counts should be |
946 |
> |
* tuning fork/join programs: in general, steal counts should be |
947 |
|
* high enough to keep threads busy, but low enough to avoid |
948 |
|
* overhead and contention across threads. |
949 |
< |
* @return the number of steals. |
949 |
> |
* |
950 |
> |
* @return the number of steals |
951 |
|
*/ |
952 |
|
public long getStealCount() { |
953 |
|
return stealCount.get(); |
954 |
|
} |
955 |
|
|
956 |
|
/** |
957 |
< |
* Accumulate steal count from a worker. Call only |
958 |
< |
* when worker known to be idle. |
957 |
> |
* Accumulates steal count from a worker. |
958 |
> |
* Call only when worker known to be idle. |
959 |
|
*/ |
960 |
|
private void updateStealCount(ForkJoinWorkerThread w) { |
961 |
|
int sc = w.getAndClearStealCount(); |
970 |
|
* an approximation, obtained by iterating across all threads in |
971 |
|
* the pool. This method may be useful for tuning task |
972 |
|
* granularities. |
973 |
< |
* @return the number of queued tasks. |
973 |
> |
* |
974 |
> |
* @return the number of queued tasks |
975 |
|
*/ |
976 |
|
public long getQueuedTaskCount() { |
977 |
|
long count = 0; |
987 |
|
} |
988 |
|
|
989 |
|
/** |
990 |
< |
* Returns an estimate of the number tasks submitted to this pool |
991 |
< |
* that have not yet begun executing. This method takes time |
990 |
> |
* Returns an estimate of the number of tasks submitted to this |
991 |
> |
* pool that have not yet begun executing. This method takes time |
992 |
|
* proportional to the number of submissions. |
993 |
< |
* @return the number of queued submissions. |
993 |
> |
* |
994 |
> |
* @return the number of queued submissions |
995 |
|
*/ |
996 |
|
public int getQueuedSubmissionCount() { |
997 |
|
return submissionQueue.size(); |
998 |
|
} |
999 |
|
|
1000 |
|
/** |
1001 |
< |
* Returns true if there are any tasks submitted to this pool |
1002 |
< |
* that have not yet begun executing. |
1003 |
< |
* @return {@code true} if there are any queued submissions. |
1001 |
> |
* Returns {@code true} if there are any tasks submitted to this |
1002 |
> |
* pool that have not yet begun executing. |
1003 |
> |
* |
1004 |
> |
* @return {@code true} if there are any queued submissions |
1005 |
|
*/ |
1006 |
|
public boolean hasQueuedSubmissions() { |
1007 |
|
return !submissionQueue.isEmpty(); |
1011 |
|
* Removes and returns the next unexecuted submission if one is |
1012 |
|
* available. This method may be useful in extensions to this |
1013 |
|
* class that re-assign work in systems with multiple pools. |
1014 |
< |
* @return the next submission, or null if none |
1014 |
> |
* |
1015 |
> |
* @return the next submission, or {@code null} if none |
1016 |
|
*/ |
1017 |
|
protected ForkJoinTask<?> pollSubmission() { |
1018 |
|
return submissionQueue.poll(); |
1022 |
|
* Removes all available unexecuted submitted and forked tasks |
1023 |
|
* from scheduling queues and adds them to the given collection, |
1024 |
|
* without altering their execution status. These may include |
1025 |
< |
* artificially generated or wrapped tasks. This method is designed |
1026 |
< |
* to be invoked only when the pool is known to be |
1025 |
> |
* artificially generated or wrapped tasks. This method is |
1026 |
> |
* designed to be invoked only when the pool is known to be |
1027 |
|
* quiescent. Invocations at other times may not remove all |
1028 |
|
* tasks. A failure encountered while attempting to add elements |
1029 |
|
* to collection {@code c} may result in elements being in |
1031 |
|
* exception is thrown. The behavior of this operation is |
1032 |
|
* undefined if the specified collection is modified while the |
1033 |
|
* operation is in progress. |
1034 |
+ |
* |
1035 |
|
* @param c the collection to transfer elements into |
1036 |
|
* @return the number of elements transferred |
1037 |
|
*/ |
1038 |
< |
protected int drainTasksTo(Collection<ForkJoinTask<?>> c) { |
1038 |
> |
protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) { |
1039 |
|
int n = submissionQueue.drainTo(c); |
1040 |
|
ForkJoinWorkerThread[] ws = workers; |
1041 |
|
if (ws != null) { |
1092 |
|
* Invocation has no additional effect if already shut down. |
1093 |
|
* Tasks that are in the process of being submitted concurrently |
1094 |
|
* during the course of this method may or may not be rejected. |
1095 |
+ |
* |
1096 |
|
* @throws SecurityException if a security manager exists and |
1097 |
|
* the caller is not permitted to modify threads |
1098 |
|
* because it does not hold {@link |
1099 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
1099 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1100 |
|
*/ |
1101 |
|
public void shutdown() { |
1102 |
|
checkPermission(); |
1103 |
|
transitionRunStateTo(SHUTDOWN); |
1104 |
< |
if (canTerminateOnShutdown(runControl)) |
1104 |
> |
if (canTerminateOnShutdown(runControl)) { |
1105 |
> |
if (workers == null) { // shutting down before workers created |
1106 |
> |
final ReentrantLock lock = this.workerLock; |
1107 |
> |
lock.lock(); |
1108 |
> |
try { |
1109 |
> |
if (workers == null) { |
1110 |
> |
terminate(); |
1111 |
> |
transitionRunStateTo(TERMINATED); |
1112 |
> |
termination.signalAll(); |
1113 |
> |
} |
1114 |
> |
} finally { |
1115 |
> |
lock.unlock(); |
1116 |
> |
} |
1117 |
> |
} |
1118 |
|
terminateOnShutdown(); |
1119 |
+ |
} |
1120 |
|
} |
1121 |
|
|
1122 |
|
/** |
1123 |
< |
* Attempts to stop all actively executing tasks, and cancels all |
1124 |
< |
* waiting tasks. Tasks that are in the process of being |
1125 |
< |
* submitted or executed concurrently during the course of this |
1126 |
< |
* method may or may not be rejected. Unlike some other executors, |
1127 |
< |
* this method cancels rather than collects non-executed tasks |
1128 |
< |
* upon termination, so always returns an empty list. However, you |
1129 |
< |
* can use method {@code drainTasksTo} before invoking this |
1130 |
< |
* method to transfer unexecuted tasks to another collection. |
1123 |
> |
* Attempts to cancel and/or stop all tasks, and reject all |
1124 |
> |
* subsequently submitted tasks. Tasks that are in the process of |
1125 |
> |
* being submitted or executed concurrently during the course of |
1126 |
> |
* this method may or may not be rejected. This method cancels |
1127 |
> |
* both existing and unexecuted tasks, in order to permit |
1128 |
> |
* termination in the presence of task dependencies. So the method |
1129 |
> |
* always returns an empty list (unlike the case for some other |
1130 |
> |
* Executors). |
1131 |
> |
* |
1132 |
|
* @return an empty list |
1133 |
|
* @throws SecurityException if a security manager exists and |
1134 |
|
* the caller is not permitted to modify threads |
1135 |
|
* because it does not hold {@link |
1136 |
< |
* java.lang.RuntimePermission}{@code ("modifyThread")}, |
1136 |
> |
* java.lang.RuntimePermission}{@code ("modifyThread")} |
1137 |
|
*/ |
1138 |
|
public List<Runnable> shutdownNow() { |
1139 |
|
checkPermission(); |
1152 |
|
|
1153 |
|
/** |
1154 |
|
* Returns {@code true} if the process of termination has |
1155 |
< |
* commenced but possibly not yet completed. |
1155 |
> |
* commenced but not yet completed. This method may be useful for |
1156 |
> |
* debugging. A return of {@code true} reported a sufficient |
1157 |
> |
* period after shutdown may indicate that submitted tasks have |
1158 |
> |
* ignored or suppressed interruption, causing this executor not |
1159 |
> |
* to properly terminate. |
1160 |
|
* |
1161 |
< |
* @return {@code true} if terminating |
1161 |
> |
* @return {@code true} if terminating but not yet terminated |
1162 |
|
*/ |
1163 |
|
public boolean isTerminating() { |
1164 |
< |
return runStateOf(runControl) >= TERMINATING; |
1164 |
> |
return runStateOf(runControl) == TERMINATING; |
1165 |
|
} |
1166 |
|
|
1167 |
|
/** |
1174 |
|
} |
1175 |
|
|
1176 |
|
/** |
1177 |
+ |
* Returns true if pool is not terminating or terminated. |
1178 |
+ |
* Used internally to suppress execution when terminating. |
1179 |
+ |
*/ |
1180 |
+ |
final boolean isProcessingTasks() { |
1181 |
+ |
return runStateOf(runControl) < TERMINATING; |
1182 |
+ |
} |
1183 |
+ |
|
1184 |
+ |
/** |
1185 |
|
* Blocks until all tasks have completed execution after a shutdown |
1186 |
|
* request, or the timeout occurs, or the current thread is |
1187 |
|
* interrupted, whichever happens first. |
1213 |
|
// Shutdown and termination support |
1214 |
|
|
1215 |
|
/** |
1216 |
< |
* Callback from terminating worker. Null out the corresponding |
1217 |
< |
* workers slot, and if terminating, try to terminate, else try to |
1218 |
< |
* shrink workers array. |
1216 |
> |
* Callback from terminating worker. Nulls out the corresponding |
1217 |
> |
* workers slot, and if terminating, tries to terminate; else |
1218 |
> |
* tries to shrink workers array. |
1219 |
> |
* |
1220 |
|
* @param w the worker |
1221 |
|
*/ |
1222 |
|
final void workerTerminated(ForkJoinWorkerThread w) { |
1235 |
|
transitionRunStateTo(TERMINATED); |
1236 |
|
termination.signalAll(); |
1237 |
|
} |
1238 |
< |
else if (!isTerminating()) { |
1238 |
> |
else if (isProcessingTasks()) { |
1239 |
|
tryShrinkWorkerArray(); |
1240 |
|
tryResumeSpare(true); // allow replacement |
1241 |
|
} |
1247 |
|
} |
1248 |
|
|
1249 |
|
/** |
1250 |
< |
* Initiate termination. |
1250 |
> |
* Initiates termination. |
1251 |
|
*/ |
1252 |
|
private void terminate() { |
1253 |
|
if (transitionRunStateTo(TERMINATING)) { |
1424 |
|
* Ensures that no thread is waiting for count to advance from the |
1425 |
|
* current value of eventCount read on entry to this method, by |
1426 |
|
* releasing waiting threads if necessary. |
1427 |
+ |
* |
1428 |
|
* @return the count |
1429 |
|
*/ |
1430 |
|
final long ensureSync() { |
1446 |
|
*/ |
1447 |
|
private void signalIdleWorkers() { |
1448 |
|
long c; |
1449 |
< |
do;while (!casEventCount(c = eventCount, c+1)); |
1449 |
> |
do {} while (!casEventCount(c = eventCount, c+1)); |
1450 |
|
ensureSync(); |
1451 |
|
} |
1452 |
|
|
1470 |
|
* Waits until event count advances from last value held by |
1471 |
|
* caller, or if excess threads, caller is resumed as spare, or |
1472 |
|
* caller or pool is terminating. Updates caller's event on exit. |
1473 |
+ |
* |
1474 |
|
* @param w the calling worker thread |
1475 |
|
*/ |
1476 |
|
final void sync(ForkJoinWorkerThread w) { |
1477 |
|
updateStealCount(w); // Transfer w's count while it is idle |
1478 |
|
|
1479 |
< |
while (!w.isShutdown() && !isTerminating() && !suspendIfSpare(w)) { |
1479 |
> |
while (!w.isShutdown() && isProcessingTasks() && !suspendIfSpare(w)) { |
1480 |
|
long prev = w.lastEventCount; |
1481 |
|
WaitQueueNode node = null; |
1482 |
|
WaitQueueNode h; |
1498 |
|
} |
1499 |
|
|
1500 |
|
/** |
1501 |
< |
* Returns true if worker waiting on sync can proceed: |
1501 |
> |
* Returns {@code true} if worker waiting on sync can proceed: |
1502 |
|
* - on signal (thread == null) |
1503 |
|
* - on event count advance (winning race to notify vs signaller) |
1504 |
< |
* - on Interrupt |
1504 |
> |
* - on interrupt |
1505 |
|
* - if the first queued node, we find work available |
1506 |
|
* If node was not signalled and event count not advanced on exit, |
1507 |
|
* then we also help advance event count. |
1508 |
< |
* @return true if node can be released |
1508 |
> |
* |
1509 |
> |
* @return {@code true} if node can be released |
1510 |
|
*/ |
1511 |
|
final boolean syncIsReleasable(WaitQueueNode node) { |
1512 |
|
long prev = node.count; |
1525 |
|
} |
1526 |
|
|
1527 |
|
/** |
1528 |
< |
* Returns true if a new sync event occurred since last call to |
1529 |
< |
* sync or this method, if so, updating caller's count. |
1528 |
> |
* Returns {@code true} if a new sync event occurred since last |
1529 |
> |
* call to sync or this method, if so, updating caller's count. |
1530 |
|
*/ |
1531 |
|
final boolean hasNewSyncEvent(ForkJoinWorkerThread w) { |
1532 |
|
long lc = w.lastEventCount; |
1546 |
|
* spare thread when one is about to block (and remove or |
1547 |
|
* suspend it later when unblocked -- see suspendIfSpare). |
1548 |
|
* However, implementing this idea requires coping with |
1549 |
< |
* several problems: We have imperfect information about the |
1549 |
> |
* several problems: we have imperfect information about the |
1550 |
|
* states of threads. Some count updates can and usually do |
1551 |
|
* lag run state changes, despite arrangements to keep them |
1552 |
|
* accurate (for example, when possible, updating counts |
1569 |
|
* target counts, else create only to avoid starvation |
1570 |
|
* @return true if joinMe known to be done |
1571 |
|
*/ |
1572 |
< |
final boolean preJoin(ForkJoinTask<?> joinMe, boolean maintainParallelism) { |
1572 |
> |
final boolean preJoin(ForkJoinTask<?> joinMe, |
1573 |
> |
boolean maintainParallelism) { |
1574 |
|
maintainParallelism &= maintainsParallelism; // overrride |
1575 |
|
boolean dec = false; // true when running count decremented |
1576 |
|
while (spareStack == null || !tryResumeSpare(dec)) { |
1577 |
|
int counts = workerCounts; |
1578 |
< |
if (dec || (dec = casWorkerCounts(counts, --counts))) { // CAS cheat |
1578 |
> |
if (dec || (dec = casWorkerCounts(counts, --counts))) { |
1579 |
> |
// CAS cheat |
1580 |
|
if (!needSpare(counts, maintainParallelism)) |
1581 |
|
break; |
1582 |
|
if (joinMe.status < 0) |
1591 |
|
/** |
1592 |
|
* Same idea as preJoin |
1593 |
|
*/ |
1594 |
< |
final boolean preBlock(ManagedBlocker blocker, boolean maintainParallelism){ |
1594 |
> |
final boolean preBlock(ManagedBlocker blocker, |
1595 |
> |
boolean maintainParallelism) { |
1596 |
|
maintainParallelism &= maintainsParallelism; |
1597 |
|
boolean dec = false; |
1598 |
|
while (spareStack == null || !tryResumeSpare(dec)) { |
1610 |
|
} |
1611 |
|
|
1612 |
|
/** |
1613 |
< |
* Returns true if a spare thread appears to be needed. If |
1614 |
< |
* maintaining parallelism, returns true when the deficit in |
1613 |
> |
* Returns {@code true} if a spare thread appears to be needed. |
1614 |
> |
* If maintaining parallelism, returns true when the deficit in |
1615 |
|
* running threads is more than the surplus of total threads, and |
1616 |
|
* there is apparently some work to do. This self-limiting rule |
1617 |
|
* means that the more threads that have already been added, the |
1618 |
|
* less parallelism we will tolerate before adding another. |
1619 |
+ |
* |
1620 |
|
* @param counts current worker counts |
1621 |
|
* @param maintainParallelism try to maintain parallelism |
1622 |
|
*/ |
1636 |
|
/** |
1637 |
|
* Adds a spare worker if lock available and no more than the |
1638 |
|
* expected numbers of threads exist. |
1639 |
+ |
* |
1640 |
|
* @return true if successful |
1641 |
|
*/ |
1642 |
|
private boolean tryAddSpare(int expectedCounts) { |
1681 |
|
for (k = 0; k < len && ws[k] != null; ++k) |
1682 |
|
; |
1683 |
|
} |
1684 |
< |
if (k < len && !isTerminating() && (w = createWorker(k)) != null) { |
1684 |
> |
if (k < len && isProcessingTasks() && (w = createWorker(k)) != null) { |
1685 |
|
ws[k] = w; |
1686 |
|
w.start(); |
1687 |
|
} |
1696 |
|
* the same WaitQueueNodes as barriers. They are resumed mainly |
1697 |
|
* in preJoin, but are also woken on pool events that require all |
1698 |
|
* threads to check run state. |
1699 |
+ |
* |
1700 |
|
* @param w the caller |
1701 |
|
*/ |
1702 |
|
private boolean suspendIfSpare(ForkJoinWorkerThread w) { |
1707 |
|
node = new WaitQueueNode(0, w); |
1708 |
|
if (casWorkerCounts(s, s-1)) { // representation-dependent |
1709 |
|
// push onto stack |
1710 |
< |
do;while (!casSpareStack(node.next = spareStack, node)); |
1710 |
> |
do {} while (!casSpareStack(node.next = spareStack, node)); |
1711 |
|
// block until released by resumeSpare |
1712 |
|
node.awaitSpareRelease(); |
1713 |
|
return true; |
1718 |
|
|
1719 |
|
/** |
1720 |
|
* Tries to pop and resume a spare thread. |
1721 |
+ |
* |
1722 |
|
* @param updateCount if true, increment running count on success |
1723 |
|
* @return true if successful |
1724 |
|
*/ |
1737 |
|
|
1738 |
|
/** |
1739 |
|
* Pops and resumes all spare threads. Same idea as ensureSync. |
1740 |
+ |
* |
1741 |
|
* @return true if any spares released |
1742 |
|
*/ |
1743 |
|
private boolean resumeAllSpares() { |
1779 |
|
|
1780 |
|
/** |
1781 |
|
* Interface for extending managed parallelism for tasks running |
1782 |
< |
* in ForkJoinPools. A ManagedBlocker provides two methods. |
1783 |
< |
* Method {@code isReleasable} must return true if blocking is not |
1784 |
< |
* necessary. Method {@code block} blocks the current thread |
1785 |
< |
* if necessary (perhaps internally invoking isReleasable before |
1786 |
< |
* actually blocking.). |
1782 |
> |
* in {@link ForkJoinPool}s. |
1783 |
> |
* |
1784 |
> |
* <p>A {@code ManagedBlocker} provides two methods. |
1785 |
> |
* Method {@code isReleasable} must return {@code true} if |
1786 |
> |
* blocking is not necessary. Method {@code block} blocks the |
1787 |
> |
* current thread if necessary (perhaps internally invoking |
1788 |
> |
* {@code isReleasable} before actually blocking). |
1789 |
> |
* |
1790 |
|
* <p>For example, here is a ManagedBlocker based on a |
1791 |
|
* ReentrantLock: |
1792 |
< |
* <pre> |
1793 |
< |
* class ManagedLocker implements ManagedBlocker { |
1794 |
< |
* final ReentrantLock lock; |
1795 |
< |
* boolean hasLock = false; |
1796 |
< |
* ManagedLocker(ReentrantLock lock) { this.lock = lock; } |
1797 |
< |
* public boolean block() { |
1798 |
< |
* if (!hasLock) |
1799 |
< |
* lock.lock(); |
1800 |
< |
* return true; |
1801 |
< |
* } |
1802 |
< |
* public boolean isReleasable() { |
1803 |
< |
* return hasLock || (hasLock = lock.tryLock()); |
1711 |
< |
* } |
1792 |
> |
* <pre> {@code |
1793 |
> |
* class ManagedLocker implements ManagedBlocker { |
1794 |
> |
* final ReentrantLock lock; |
1795 |
> |
* boolean hasLock = false; |
1796 |
> |
* ManagedLocker(ReentrantLock lock) { this.lock = lock; } |
1797 |
> |
* public boolean block() { |
1798 |
> |
* if (!hasLock) |
1799 |
> |
* lock.lock(); |
1800 |
> |
* return true; |
1801 |
> |
* } |
1802 |
> |
* public boolean isReleasable() { |
1803 |
> |
* return hasLock || (hasLock = lock.tryLock()); |
1804 |
|
* } |
1805 |
< |
* </pre> |
1805 |
> |
* }}</pre> |
1806 |
|
*/ |
1807 |
|
public static interface ManagedBlocker { |
1808 |
|
/** |
1809 |
|
* Possibly blocks the current thread, for example waiting for |
1810 |
|
* a lock or condition. |
1811 |
< |
* @return true if no additional blocking is necessary (i.e., |
1812 |
< |
* if isReleasable would return true). |
1811 |
> |
* |
1812 |
> |
* @return {@code true} if no additional blocking is necessary |
1813 |
> |
* (i.e., if isReleasable would return true) |
1814 |
|
* @throws InterruptedException if interrupted while waiting |
1815 |
< |
* (the method is not required to do so, but is allowed to). |
1815 |
> |
* (the method is not required to do so, but is allowed to) |
1816 |
|
*/ |
1817 |
|
boolean block() throws InterruptedException; |
1818 |
|
|
1819 |
|
/** |
1820 |
< |
* Returns true if blocking is unnecessary. |
1820 |
> |
* Returns {@code true} if blocking is unnecessary. |
1821 |
|
*/ |
1822 |
|
boolean isReleasable(); |
1823 |
|
} |
1824 |
|
|
1825 |
|
/** |
1826 |
|
* Blocks in accord with the given blocker. If the current thread |
1827 |
< |
* is a ForkJoinWorkerThread, this method possibly arranges for a |
1828 |
< |
* spare thread to be activated if necessary to ensure parallelism |
1829 |
< |
* while the current thread is blocked. If |
1830 |
< |
* {@code maintainParallelism} is true and the pool supports |
1831 |
< |
* it ({@link #getMaintainsParallelism}), this method attempts to |
1832 |
< |
* maintain the pool's nominal parallelism. Otherwise if activates |
1833 |
< |
* a thread only if necessary to avoid complete starvation. This |
1834 |
< |
* option may be preferable when blockages use timeouts, or are |
1835 |
< |
* almost always brief. |
1836 |
< |
* |
1837 |
< |
* <p> If the caller is not a ForkJoinTask, this method is behaviorally |
1838 |
< |
* equivalent to |
1839 |
< |
* <pre> |
1840 |
< |
* while (!blocker.isReleasable()) |
1841 |
< |
* if (blocker.block()) |
1842 |
< |
* return; |
1843 |
< |
* </pre> |
1844 |
< |
* If the caller is a ForkJoinTask, then the pool may first |
1845 |
< |
* be expanded to ensure parallelism, and later adjusted. |
1827 |
> |
* is a {@link ForkJoinWorkerThread}, this method possibly |
1828 |
> |
* arranges for a spare thread to be activated if necessary to |
1829 |
> |
* ensure parallelism while the current thread is blocked. |
1830 |
> |
* |
1831 |
> |
* <p>If {@code maintainParallelism} is {@code true} and the pool |
1832 |
> |
* supports it ({@link #getMaintainsParallelism}), this method |
1833 |
> |
* attempts to maintain the pool's nominal parallelism. Otherwise |
1834 |
> |
* it activates a thread only if necessary to avoid complete |
1835 |
> |
* starvation. This option may be preferable when blockages use |
1836 |
> |
* timeouts, or are almost always brief. |
1837 |
> |
* |
1838 |
> |
* <p>If the caller is not a {@link ForkJoinTask}, this method is |
1839 |
> |
* behaviorally equivalent to |
1840 |
> |
* <pre> {@code |
1841 |
> |
* while (!blocker.isReleasable()) |
1842 |
> |
* if (blocker.block()) |
1843 |
> |
* return; |
1844 |
> |
* }</pre> |
1845 |
> |
* |
1846 |
> |
* If the caller is a {@code ForkJoinTask}, then the pool may |
1847 |
> |
* first be expanded to ensure parallelism, and later adjusted. |
1848 |
|
* |
1849 |
|
* @param blocker the blocker |
1850 |
< |
* @param maintainParallelism if true and supported by this pool, |
1851 |
< |
* attempt to maintain the pool's nominal parallelism; otherwise |
1852 |
< |
* activate a thread only if necessary to avoid complete |
1853 |
< |
* starvation. |
1854 |
< |
* @throws InterruptedException if blocker.block did so. |
1850 |
> |
* @param maintainParallelism if {@code true} and supported by |
1851 |
> |
* this pool, attempt to maintain the pool's nominal parallelism; |
1852 |
> |
* otherwise activate a thread only if necessary to avoid |
1853 |
> |
* complete starvation. |
1854 |
> |
* @throws InterruptedException if blocker.block did so |
1855 |
|
*/ |
1856 |
|
public static void managedBlock(ManagedBlocker blocker, |
1857 |
|
boolean maintainParallelism) |
1858 |
|
throws InterruptedException { |
1859 |
|
Thread t = Thread.currentThread(); |
1860 |
< |
ForkJoinPool pool = (t instanceof ForkJoinWorkerThread? |
1861 |
< |
((ForkJoinWorkerThread)t).pool : null); |
1860 |
> |
ForkJoinPool pool = ((t instanceof ForkJoinWorkerThread) ? |
1861 |
> |
((ForkJoinWorkerThread) t).pool : null); |
1862 |
|
if (!blocker.isReleasable()) { |
1863 |
|
try { |
1864 |
|
if (pool == null || |
1873 |
|
|
1874 |
|
private static void awaitBlocker(ManagedBlocker blocker) |
1875 |
|
throws InterruptedException { |
1876 |
< |
do;while (!blocker.isReleasable() && !blocker.block()); |
1876 |
> |
do {} while (!blocker.isReleasable() && !blocker.block()); |
1877 |
|
} |
1878 |
|
|
1879 |
< |
// AbstractExecutorService overrides |
1879 |
> |
// AbstractExecutorService overrides. These rely on undocumented |
1880 |
> |
// fact that ForkJoinTask.adapt returns ForkJoinTasks that also |
1881 |
> |
// implement RunnableFuture. |
1882 |
|
|
1883 |
|
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { |
1884 |
< |
return new AdaptedRunnable(runnable, value); |
1884 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value); |
1885 |
|
} |
1886 |
|
|
1887 |
|
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { |
1888 |
< |
return new AdaptedCallable(callable); |
1888 |
> |
return (RunnableFuture<T>) ForkJoinTask.adapt(callable); |
1889 |
|
} |
1890 |
|
|
1891 |
+ |
// Unsafe mechanics |
1892 |
|
|
1893 |
< |
// Temporary Unsafe mechanics for preliminary release |
1894 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1895 |
< |
try { |
1896 |
< |
return Unsafe.getUnsafe(); |
1897 |
< |
} catch (SecurityException se) { |
1898 |
< |
try { |
1899 |
< |
return java.security.AccessController.doPrivileged |
1900 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1901 |
< |
public Unsafe run() throws Exception { |
1902 |
< |
return getUnsafePrivileged(); |
1903 |
< |
}}); |
1806 |
< |
} catch (java.security.PrivilegedActionException e) { |
1807 |
< |
throw e.getCause(); |
1808 |
< |
} |
1809 |
< |
} |
1810 |
< |
} |
1811 |
< |
|
1812 |
< |
private static Unsafe getUnsafePrivileged() |
1813 |
< |
throws NoSuchFieldException, IllegalAccessException { |
1814 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1815 |
< |
f.setAccessible(true); |
1816 |
< |
return (Unsafe) f.get(null); |
1817 |
< |
} |
1818 |
< |
|
1819 |
< |
private static long fieldOffset(String fieldName) |
1820 |
< |
throws NoSuchFieldException { |
1821 |
< |
return _unsafe.objectFieldOffset |
1822 |
< |
(ForkJoinPool.class.getDeclaredField(fieldName)); |
1823 |
< |
} |
1824 |
< |
|
1825 |
< |
static final Unsafe _unsafe; |
1826 |
< |
static final long eventCountOffset; |
1827 |
< |
static final long workerCountsOffset; |
1828 |
< |
static final long runControlOffset; |
1829 |
< |
static final long syncStackOffset; |
1830 |
< |
static final long spareStackOffset; |
1831 |
< |
|
1832 |
< |
static { |
1833 |
< |
try { |
1834 |
< |
_unsafe = getUnsafe(); |
1835 |
< |
eventCountOffset = fieldOffset("eventCount"); |
1836 |
< |
workerCountsOffset = fieldOffset("workerCounts"); |
1837 |
< |
runControlOffset = fieldOffset("runControl"); |
1838 |
< |
syncStackOffset = fieldOffset("syncStack"); |
1839 |
< |
spareStackOffset = fieldOffset("spareStack"); |
1840 |
< |
} catch (Throwable e) { |
1841 |
< |
throw new RuntimeException("Could not initialize intrinsics", e); |
1842 |
< |
} |
1843 |
< |
} |
1893 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1894 |
> |
private static final long eventCountOffset = |
1895 |
> |
objectFieldOffset("eventCount", ForkJoinPool.class); |
1896 |
> |
private static final long workerCountsOffset = |
1897 |
> |
objectFieldOffset("workerCounts", ForkJoinPool.class); |
1898 |
> |
private static final long runControlOffset = |
1899 |
> |
objectFieldOffset("runControl", ForkJoinPool.class); |
1900 |
> |
private static final long syncStackOffset = |
1901 |
> |
objectFieldOffset("syncStack",ForkJoinPool.class); |
1902 |
> |
private static final long spareStackOffset = |
1903 |
> |
objectFieldOffset("spareStack", ForkJoinPool.class); |
1904 |
|
|
1905 |
|
private boolean casEventCount(long cmp, long val) { |
1906 |
< |
return _unsafe.compareAndSwapLong(this, eventCountOffset, cmp, val); |
1906 |
> |
return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val); |
1907 |
|
} |
1908 |
|
private boolean casWorkerCounts(int cmp, int val) { |
1909 |
< |
return _unsafe.compareAndSwapInt(this, workerCountsOffset, cmp, val); |
1909 |
> |
return UNSAFE.compareAndSwapInt(this, workerCountsOffset, cmp, val); |
1910 |
|
} |
1911 |
|
private boolean casRunControl(int cmp, int val) { |
1912 |
< |
return _unsafe.compareAndSwapInt(this, runControlOffset, cmp, val); |
1912 |
> |
return UNSAFE.compareAndSwapInt(this, runControlOffset, cmp, val); |
1913 |
|
} |
1914 |
|
private boolean casSpareStack(WaitQueueNode cmp, WaitQueueNode val) { |
1915 |
< |
return _unsafe.compareAndSwapObject(this, spareStackOffset, cmp, val); |
1915 |
> |
return UNSAFE.compareAndSwapObject(this, spareStackOffset, cmp, val); |
1916 |
|
} |
1917 |
|
private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) { |
1918 |
< |
return _unsafe.compareAndSwapObject(this, syncStackOffset, cmp, val); |
1918 |
> |
return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val); |
1919 |
> |
} |
1920 |
> |
|
1921 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1922 |
> |
try { |
1923 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1924 |
> |
} catch (NoSuchFieldException e) { |
1925 |
> |
// Convert Exception to corresponding Error |
1926 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1927 |
> |
error.initCause(e); |
1928 |
> |
throw error; |
1929 |
> |
} |
1930 |
> |
} |
1931 |
> |
|
1932 |
> |
/** |
1933 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1934 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1935 |
> |
* into a jdk. |
1936 |
> |
* |
1937 |
> |
* @return a sun.misc.Unsafe |
1938 |
> |
*/ |
1939 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1940 |
> |
try { |
1941 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1942 |
> |
} catch (SecurityException se) { |
1943 |
> |
try { |
1944 |
> |
return java.security.AccessController.doPrivileged |
1945 |
> |
(new java.security |
1946 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1947 |
> |
public sun.misc.Unsafe run() throws Exception { |
1948 |
> |
java.lang.reflect.Field f = sun.misc |
1949 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1950 |
> |
f.setAccessible(true); |
1951 |
> |
return (sun.misc.Unsafe) f.get(null); |
1952 |
> |
}}); |
1953 |
> |
} catch (java.security.PrivilegedActionException e) { |
1954 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1955 |
> |
e.getCause()); |
1956 |
> |
} |
1957 |
> |
} |
1958 |
|
} |
1959 |
|
} |