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root/jsr166/jsr166/src/main/java/util/concurrent/Executors.java
Revision: 1.82
Committed: Wed Jan 16 01:59:47 2013 UTC (11 years, 4 months ago) by jsr166
Branch: MAIN
Changes since 1.81: +18 -18 lines
Log Message:
<tt> -> {@code

File Contents

# Content
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 * http://creativecommons.org/publicdomain/zero/1.0/
5 */
6
7 package java.util.concurrent;
8 import java.util.*;
9 import java.util.concurrent.atomic.AtomicInteger;
10 import java.security.AccessControlContext;
11 import java.security.AccessController;
12 import java.security.PrivilegedAction;
13 import java.security.PrivilegedExceptionAction;
14 import java.security.PrivilegedActionException;
15 import java.security.AccessControlException;
16 import sun.security.util.SecurityConstants;
17
18 /**
19 * Factory and utility methods for {@link Executor}, {@link
20 * ExecutorService}, {@link ScheduledExecutorService}, {@link
21 * ThreadFactory}, and {@link Callable} classes defined in this
22 * package. This class supports the following kinds of methods:
23 *
24 * <ul>
25 * <li> Methods that create and return an {@link ExecutorService}
26 * set up with commonly useful configuration settings.
27 * <li> Methods that create and return a {@link ScheduledExecutorService}
28 * set up with commonly useful configuration settings.
29 * <li> Methods that create and return a "wrapped" ExecutorService, that
30 * disables reconfiguration by making implementation-specific methods
31 * inaccessible.
32 * <li> Methods that create and return a {@link ThreadFactory}
33 * that sets newly created threads to a known state.
34 * <li> Methods that create and return a {@link Callable}
35 * out of other closure-like forms, so they can be used
36 * in execution methods requiring {@code Callable}.
37 * </ul>
38 *
39 * @since 1.5
40 * @author Doug Lea
41 */
42 public class Executors {
43
44 /**
45 * Creates a thread pool that reuses a fixed number of threads
46 * operating off a shared unbounded queue. At any point, at most
47 * {@code nThreads} threads will be active processing tasks.
48 * If additional tasks are submitted when all threads are active,
49 * they will wait in the queue until a thread is available.
50 * If any thread terminates due to a failure during execution
51 * prior to shutdown, a new one will take its place if needed to
52 * execute subsequent tasks. The threads in the pool will exist
53 * until it is explicitly {@link ExecutorService#shutdown shutdown}.
54 *
55 * @param nThreads the number of threads in the pool
56 * @return the newly created thread pool
57 * @throws IllegalArgumentException if {@code nThreads <= 0}
58 */
59 public static ExecutorService newFixedThreadPool(int nThreads) {
60 return new ThreadPoolExecutor(nThreads, nThreads,
61 0L, TimeUnit.MILLISECONDS,
62 new LinkedBlockingQueue<Runnable>());
63 }
64
65 /**
66 * Creates a thread pool that maintains enough threads to support
67 * the given parallelism level, and may use multiple queues to
68 * reduce contention. The parallelism level corresponds to the
69 * maximum number of threads actively engaged in, or available to
70 * engage in, task processing. The actual number of threads may
71 * grow and shrink dynamically. A work-stealing pool makes no
72 * guarantees about the order in which submitted tasks are
73 * executed.
74 *
75 * @param parallelism the targeted parallelism level
76 * @return the newly created thread pool
77 * @throws IllegalArgumentException if {@code parallelism <= 0}
78 * @since 1.8
79 */
80 public static ExecutorService newWorkStealingPool(int parallelism) {
81 return new ForkJoinPool
82 (parallelism,
83 ForkJoinPool.defaultForkJoinWorkerThreadFactory,
84 null, true);
85 }
86
87 /**
88 * Creates a work-stealing thread pool using all
89 * (@link Runtime#availableProcessors available processors}
90 * as its target parallelism level.
91 * @return the newly created thread pool
92 * @since 1.8
93 */
94 public static ExecutorService newWorkStealingPool() {
95 return new ForkJoinPool
96 (Runtime.getRuntime().availableProcessors(),
97 ForkJoinPool.defaultForkJoinWorkerThreadFactory,
98 null, true);
99 }
100
101 /**
102 * Creates a thread pool that reuses a fixed number of threads
103 * operating off a shared unbounded queue, using the provided
104 * ThreadFactory to create new threads when needed. At any point,
105 * at most {@code nThreads} threads will be active processing
106 * tasks. If additional tasks are submitted when all threads are
107 * active, they will wait in the queue until a thread is
108 * available. If any thread terminates due to a failure during
109 * execution prior to shutdown, a new one will take its place if
110 * needed to execute subsequent tasks. The threads in the pool will
111 * exist until it is explicitly {@link ExecutorService#shutdown
112 * shutdown}.
113 *
114 * @param nThreads the number of threads in the pool
115 * @param threadFactory the factory to use when creating new threads
116 * @return the newly created thread pool
117 * @throws NullPointerException if threadFactory is null
118 * @throws IllegalArgumentException if {@code nThreads <= 0}
119 */
120 public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {
121 return new ThreadPoolExecutor(nThreads, nThreads,
122 0L, TimeUnit.MILLISECONDS,
123 new LinkedBlockingQueue<Runnable>(),
124 threadFactory);
125 }
126
127 /**
128 * Creates an Executor that uses a single worker thread operating
129 * off an unbounded queue. (Note however that if this single
130 * thread terminates due to a failure during execution prior to
131 * shutdown, a new one will take its place if needed to execute
132 * subsequent tasks.) Tasks are guaranteed to execute
133 * sequentially, and no more than one task will be active at any
134 * given time. Unlike the otherwise equivalent
135 * {@code newFixedThreadPool(1)} the returned executor is
136 * guaranteed not to be reconfigurable to use additional threads.
137 *
138 * @return the newly created single-threaded Executor
139 */
140 public static ExecutorService newSingleThreadExecutor() {
141 return new FinalizableDelegatedExecutorService
142 (new ThreadPoolExecutor(1, 1,
143 0L, TimeUnit.MILLISECONDS,
144 new LinkedBlockingQueue<Runnable>()));
145 }
146
147 /**
148 * Creates an Executor that uses a single worker thread operating
149 * off an unbounded queue, and uses the provided ThreadFactory to
150 * create a new thread when needed. Unlike the otherwise
151 * equivalent {@code newFixedThreadPool(1, threadFactory)} the
152 * returned executor is guaranteed not to be reconfigurable to use
153 * additional threads.
154 *
155 * @param threadFactory the factory to use when creating new
156 * threads
157 *
158 * @return the newly created single-threaded Executor
159 * @throws NullPointerException if threadFactory is null
160 */
161 public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) {
162 return new FinalizableDelegatedExecutorService
163 (new ThreadPoolExecutor(1, 1,
164 0L, TimeUnit.MILLISECONDS,
165 new LinkedBlockingQueue<Runnable>(),
166 threadFactory));
167 }
168
169 /**
170 * Creates a thread pool that creates new threads as needed, but
171 * will reuse previously constructed threads when they are
172 * available. These pools will typically improve the performance
173 * of programs that execute many short-lived asynchronous tasks.
174 * Calls to {@code execute} will reuse previously constructed
175 * threads if available. If no existing thread is available, a new
176 * thread will be created and added to the pool. Threads that have
177 * not been used for sixty seconds are terminated and removed from
178 * the cache. Thus, a pool that remains idle for long enough will
179 * not consume any resources. Note that pools with similar
180 * properties but different details (for example, timeout parameters)
181 * may be created using {@link ThreadPoolExecutor} constructors.
182 *
183 * @return the newly created thread pool
184 */
185 public static ExecutorService newCachedThreadPool() {
186 return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
187 60L, TimeUnit.SECONDS,
188 new SynchronousQueue<Runnable>());
189 }
190
191 /**
192 * Creates a thread pool that creates new threads as needed, but
193 * will reuse previously constructed threads when they are
194 * available, and uses the provided
195 * ThreadFactory to create new threads when needed.
196 * @param threadFactory the factory to use when creating new threads
197 * @return the newly created thread pool
198 * @throws NullPointerException if threadFactory is null
199 */
200 public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
201 return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
202 60L, TimeUnit.SECONDS,
203 new SynchronousQueue<Runnable>(),
204 threadFactory);
205 }
206
207 /**
208 * Creates a single-threaded executor that can schedule commands
209 * to run after a given delay, or to execute periodically.
210 * (Note however that if this single
211 * thread terminates due to a failure during execution prior to
212 * shutdown, a new one will take its place if needed to execute
213 * subsequent tasks.) Tasks are guaranteed to execute
214 * sequentially, and no more than one task will be active at any
215 * given time. Unlike the otherwise equivalent
216 * {@code newScheduledThreadPool(1)} the returned executor is
217 * guaranteed not to be reconfigurable to use additional threads.
218 * @return the newly created scheduled executor
219 */
220 public static ScheduledExecutorService newSingleThreadScheduledExecutor() {
221 return new DelegatedScheduledExecutorService
222 (new ScheduledThreadPoolExecutor(1));
223 }
224
225 /**
226 * Creates a single-threaded executor that can schedule commands
227 * to run after a given delay, or to execute periodically. (Note
228 * however that if this single thread terminates due to a failure
229 * during execution prior to shutdown, a new one will take its
230 * place if needed to execute subsequent tasks.) Tasks are
231 * guaranteed to execute sequentially, and no more than one task
232 * will be active at any given time. Unlike the otherwise
233 * equivalent {@code newScheduledThreadPool(1, threadFactory)}
234 * the returned executor is guaranteed not to be reconfigurable to
235 * use additional threads.
236 * @param threadFactory the factory to use when creating new
237 * threads
238 * @return a newly created scheduled executor
239 * @throws NullPointerException if threadFactory is null
240 */
241 public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) {
242 return new DelegatedScheduledExecutorService
243 (new ScheduledThreadPoolExecutor(1, threadFactory));
244 }
245
246 /**
247 * Creates a thread pool that can schedule commands to run after a
248 * given delay, or to execute periodically.
249 * @param corePoolSize the number of threads to keep in the pool,
250 * even if they are idle.
251 * @return a newly created scheduled thread pool
252 * @throws IllegalArgumentException if {@code corePoolSize < 0}
253 */
254 public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
255 return new ScheduledThreadPoolExecutor(corePoolSize);
256 }
257
258 /**
259 * Creates a thread pool that can schedule commands to run after a
260 * given delay, or to execute periodically.
261 * @param corePoolSize the number of threads to keep in the pool,
262 * even if they are idle.
263 * @param threadFactory the factory to use when the executor
264 * creates a new thread.
265 * @return a newly created scheduled thread pool
266 * @throws IllegalArgumentException if {@code corePoolSize < 0}
267 * @throws NullPointerException if threadFactory is null
268 */
269 public static ScheduledExecutorService newScheduledThreadPool(
270 int corePoolSize, ThreadFactory threadFactory) {
271 return new ScheduledThreadPoolExecutor(corePoolSize, threadFactory);
272 }
273
274 /**
275 * Returns an object that delegates all defined {@link
276 * ExecutorService} methods to the given executor, but not any
277 * other methods that might otherwise be accessible using
278 * casts. This provides a way to safely "freeze" configuration and
279 * disallow tuning of a given concrete implementation.
280 * @param executor the underlying implementation
281 * @return an {@code ExecutorService} instance
282 * @throws NullPointerException if executor null
283 */
284 public static ExecutorService unconfigurableExecutorService(ExecutorService executor) {
285 if (executor == null)
286 throw new NullPointerException();
287 return new DelegatedExecutorService(executor);
288 }
289
290 /**
291 * Returns an object that delegates all defined {@link
292 * ScheduledExecutorService} methods to the given executor, but
293 * not any other methods that might otherwise be accessible using
294 * casts. This provides a way to safely "freeze" configuration and
295 * disallow tuning of a given concrete implementation.
296 * @param executor the underlying implementation
297 * @return a {@code ScheduledExecutorService} instance
298 * @throws NullPointerException if executor null
299 */
300 public static ScheduledExecutorService unconfigurableScheduledExecutorService(ScheduledExecutorService executor) {
301 if (executor == null)
302 throw new NullPointerException();
303 return new DelegatedScheduledExecutorService(executor);
304 }
305
306 /**
307 * Returns a default thread factory used to create new threads.
308 * This factory creates all new threads used by an Executor in the
309 * same {@link ThreadGroup}. If there is a {@link
310 * java.lang.SecurityManager}, it uses the group of {@link
311 * System#getSecurityManager}, else the group of the thread
312 * invoking this {@code defaultThreadFactory} method. Each new
313 * thread is created as a non-daemon thread with priority set to
314 * the smaller of {@code Thread.NORM_PRIORITY} and the maximum
315 * priority permitted in the thread group. New threads have names
316 * accessible via {@link Thread#getName} of
317 * <em>pool-N-thread-M</em>, where <em>N</em> is the sequence
318 * number of this factory, and <em>M</em> is the sequence number
319 * of the thread created by this factory.
320 * @return a thread factory
321 */
322 public static ThreadFactory defaultThreadFactory() {
323 return new DefaultThreadFactory();
324 }
325
326 /**
327 * Returns a thread factory used to create new threads that
328 * have the same permissions as the current thread.
329 * This factory creates threads with the same settings as {@link
330 * Executors#defaultThreadFactory}, additionally setting the
331 * AccessControlContext and contextClassLoader of new threads to
332 * be the same as the thread invoking this
333 * {@code privilegedThreadFactory} method. A new
334 * {@code privilegedThreadFactory} can be created within an
335 * {@link AccessController#doPrivileged} action setting the
336 * current thread's access control context to create threads with
337 * the selected permission settings holding within that action.
338 *
339 * <p>Note that while tasks running within such threads will have
340 * the same access control and class loader settings as the
341 * current thread, they need not have the same {@link
342 * java.lang.ThreadLocal} or {@link
343 * java.lang.InheritableThreadLocal} values. If necessary,
344 * particular values of thread locals can be set or reset before
345 * any task runs in {@link ThreadPoolExecutor} subclasses using
346 * {@link ThreadPoolExecutor#beforeExecute}. Also, if it is
347 * necessary to initialize worker threads to have the same
348 * InheritableThreadLocal settings as some other designated
349 * thread, you can create a custom ThreadFactory in which that
350 * thread waits for and services requests to create others that
351 * will inherit its values.
352 *
353 * @return a thread factory
354 * @throws AccessControlException if the current access control
355 * context does not have permission to both get and set context
356 * class loader.
357 */
358 public static ThreadFactory privilegedThreadFactory() {
359 return new PrivilegedThreadFactory();
360 }
361
362 /**
363 * Returns a {@link Callable} object that, when
364 * called, runs the given task and returns the given result. This
365 * can be useful when applying methods requiring a
366 * {@code Callable} to an otherwise resultless action.
367 * @param task the task to run
368 * @param result the result to return
369 * @return a callable object
370 * @throws NullPointerException if task null
371 */
372 public static <T> Callable<T> callable(Runnable task, T result) {
373 if (task == null)
374 throw new NullPointerException();
375 return new RunnableAdapter<T>(task, result);
376 }
377
378 /**
379 * Returns a {@link Callable} object that, when
380 * called, runs the given task and returns {@code null}.
381 * @param task the task to run
382 * @return a callable object
383 * @throws NullPointerException if task null
384 */
385 public static Callable<Object> callable(Runnable task) {
386 if (task == null)
387 throw new NullPointerException();
388 return new RunnableAdapter<Object>(task, null);
389 }
390
391 /**
392 * Returns a {@link Callable} object that, when
393 * called, runs the given privileged action and returns its result.
394 * @param action the privileged action to run
395 * @return a callable object
396 * @throws NullPointerException if action null
397 */
398 public static Callable<Object> callable(final PrivilegedAction<?> action) {
399 if (action == null)
400 throw new NullPointerException();
401 return new Callable<Object>() {
402 public Object call() { return action.run(); }};
403 }
404
405 /**
406 * Returns a {@link Callable} object that, when
407 * called, runs the given privileged exception action and returns
408 * its result.
409 * @param action the privileged exception action to run
410 * @return a callable object
411 * @throws NullPointerException if action null
412 */
413 public static Callable<Object> callable(final PrivilegedExceptionAction<?> action) {
414 if (action == null)
415 throw new NullPointerException();
416 return new Callable<Object>() {
417 public Object call() throws Exception { return action.run(); }};
418 }
419
420 /**
421 * Returns a {@link Callable} object that will, when
422 * called, execute the given {@code callable} under the current
423 * access control context. This method should normally be
424 * invoked within an {@link AccessController#doPrivileged} action
425 * to create callables that will, if possible, execute under the
426 * selected permission settings holding within that action; or if
427 * not possible, throw an associated {@link
428 * AccessControlException}.
429 * @param callable the underlying task
430 * @return a callable object
431 * @throws NullPointerException if callable null
432 */
433 public static <T> Callable<T> privilegedCallable(Callable<T> callable) {
434 if (callable == null)
435 throw new NullPointerException();
436 return new PrivilegedCallable<T>(callable);
437 }
438
439 /**
440 * Returns a {@link Callable} object that will, when
441 * called, execute the given {@code callable} under the current
442 * access control context, with the current context class loader
443 * as the context class loader. This method should normally be
444 * invoked within an {@link AccessController#doPrivileged} action
445 * to create callables that will, if possible, execute under the
446 * selected permission settings holding within that action; or if
447 * not possible, throw an associated {@link
448 * AccessControlException}.
449 * @param callable the underlying task
450 *
451 * @return a callable object
452 * @throws NullPointerException if callable null
453 * @throws AccessControlException if the current access control
454 * context does not have permission to both set and get context
455 * class loader.
456 */
457 public static <T> Callable<T> privilegedCallableUsingCurrentClassLoader(Callable<T> callable) {
458 if (callable == null)
459 throw new NullPointerException();
460 return new PrivilegedCallableUsingCurrentClassLoader<T>(callable);
461 }
462
463 // Non-public classes supporting the public methods
464
465 /**
466 * A callable that runs given task and returns given result
467 */
468 static final class RunnableAdapter<T> implements Callable<T> {
469 final Runnable task;
470 final T result;
471 RunnableAdapter(Runnable task, T result) {
472 this.task = task;
473 this.result = result;
474 }
475 public T call() {
476 task.run();
477 return result;
478 }
479 }
480
481 /**
482 * A callable that runs under established access control settings
483 */
484 static final class PrivilegedCallable<T> implements Callable<T> {
485 private final Callable<T> task;
486 private final AccessControlContext acc;
487
488 PrivilegedCallable(Callable<T> task) {
489 this.task = task;
490 this.acc = AccessController.getContext();
491 }
492
493 public T call() throws Exception {
494 try {
495 return AccessController.doPrivileged(
496 new PrivilegedExceptionAction<T>() {
497 public T run() throws Exception {
498 return task.call();
499 }
500 }, acc);
501 } catch (PrivilegedActionException e) {
502 throw e.getException();
503 }
504 }
505 }
506
507 /**
508 * A callable that runs under established access control settings and
509 * current ClassLoader
510 */
511 static final class PrivilegedCallableUsingCurrentClassLoader<T> implements Callable<T> {
512 private final Callable<T> task;
513 private final AccessControlContext acc;
514 private final ClassLoader ccl;
515
516 PrivilegedCallableUsingCurrentClassLoader(Callable<T> task) {
517 SecurityManager sm = System.getSecurityManager();
518 if (sm != null) {
519 // Calls to getContextClassLoader from this class
520 // never trigger a security check, but we check
521 // whether our callers have this permission anyways.
522 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
523
524 // Whether setContextClassLoader turns out to be necessary
525 // or not, we fail fast if permission is not available.
526 sm.checkPermission(new RuntimePermission("setContextClassLoader"));
527 }
528 this.task = task;
529 this.acc = AccessController.getContext();
530 this.ccl = Thread.currentThread().getContextClassLoader();
531 }
532
533 public T call() throws Exception {
534 try {
535 return AccessController.doPrivileged(
536 new PrivilegedExceptionAction<T>() {
537 public T run() throws Exception {
538 Thread t = Thread.currentThread();
539 ClassLoader cl = t.getContextClassLoader();
540 if (ccl == cl) {
541 return task.call();
542 } else {
543 t.setContextClassLoader(ccl);
544 try {
545 return task.call();
546 } finally {
547 t.setContextClassLoader(cl);
548 }
549 }
550 }
551 }, acc);
552 } catch (PrivilegedActionException e) {
553 throw e.getException();
554 }
555 }
556 }
557
558 /**
559 * The default thread factory
560 */
561 static class DefaultThreadFactory implements ThreadFactory {
562 private static final AtomicInteger poolNumber = new AtomicInteger(1);
563 private final ThreadGroup group;
564 private final AtomicInteger threadNumber = new AtomicInteger(1);
565 private final String namePrefix;
566
567 DefaultThreadFactory() {
568 SecurityManager s = System.getSecurityManager();
569 group = (s != null) ? s.getThreadGroup() :
570 Thread.currentThread().getThreadGroup();
571 namePrefix = "pool-" +
572 poolNumber.getAndIncrement() +
573 "-thread-";
574 }
575
576 public Thread newThread(Runnable r) {
577 Thread t = new Thread(group, r,
578 namePrefix + threadNumber.getAndIncrement(),
579 0);
580 if (t.isDaemon())
581 t.setDaemon(false);
582 if (t.getPriority() != Thread.NORM_PRIORITY)
583 t.setPriority(Thread.NORM_PRIORITY);
584 return t;
585 }
586 }
587
588 /**
589 * Thread factory capturing access control context and class loader
590 */
591 static class PrivilegedThreadFactory extends DefaultThreadFactory {
592 private final AccessControlContext acc;
593 private final ClassLoader ccl;
594
595 PrivilegedThreadFactory() {
596 super();
597 SecurityManager sm = System.getSecurityManager();
598 if (sm != null) {
599 // Calls to getContextClassLoader from this class
600 // never trigger a security check, but we check
601 // whether our callers have this permission anyways.
602 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
603
604 // Fail fast
605 sm.checkPermission(new RuntimePermission("setContextClassLoader"));
606 }
607 this.acc = AccessController.getContext();
608 this.ccl = Thread.currentThread().getContextClassLoader();
609 }
610
611 public Thread newThread(final Runnable r) {
612 return super.newThread(new Runnable() {
613 public void run() {
614 AccessController.doPrivileged(new PrivilegedAction<Void>() {
615 public Void run() {
616 Thread.currentThread().setContextClassLoader(ccl);
617 r.run();
618 return null;
619 }
620 }, acc);
621 }
622 });
623 }
624 }
625
626 /**
627 * A wrapper class that exposes only the ExecutorService methods
628 * of an ExecutorService implementation.
629 */
630 static class DelegatedExecutorService extends AbstractExecutorService {
631 private final ExecutorService e;
632 DelegatedExecutorService(ExecutorService executor) { e = executor; }
633 public void execute(Runnable command) { e.execute(command); }
634 public void shutdown() { e.shutdown(); }
635 public List<Runnable> shutdownNow() { return e.shutdownNow(); }
636 public boolean isShutdown() { return e.isShutdown(); }
637 public boolean isTerminated() { return e.isTerminated(); }
638 public boolean awaitTermination(long timeout, TimeUnit unit)
639 throws InterruptedException {
640 return e.awaitTermination(timeout, unit);
641 }
642 public Future<?> submit(Runnable task) {
643 return e.submit(task);
644 }
645 public <T> Future<T> submit(Callable<T> task) {
646 return e.submit(task);
647 }
648 public <T> Future<T> submit(Runnable task, T result) {
649 return e.submit(task, result);
650 }
651 public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
652 throws InterruptedException {
653 return e.invokeAll(tasks);
654 }
655 public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
656 long timeout, TimeUnit unit)
657 throws InterruptedException {
658 return e.invokeAll(tasks, timeout, unit);
659 }
660 public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
661 throws InterruptedException, ExecutionException {
662 return e.invokeAny(tasks);
663 }
664 public <T> T invokeAny(Collection<? extends Callable<T>> tasks,
665 long timeout, TimeUnit unit)
666 throws InterruptedException, ExecutionException, TimeoutException {
667 return e.invokeAny(tasks, timeout, unit);
668 }
669 }
670
671 static class FinalizableDelegatedExecutorService
672 extends DelegatedExecutorService {
673 FinalizableDelegatedExecutorService(ExecutorService executor) {
674 super(executor);
675 }
676 protected void finalize() {
677 super.shutdown();
678 }
679 }
680
681 /**
682 * A wrapper class that exposes only the ScheduledExecutorService
683 * methods of a ScheduledExecutorService implementation.
684 */
685 static class DelegatedScheduledExecutorService
686 extends DelegatedExecutorService
687 implements ScheduledExecutorService {
688 private final ScheduledExecutorService e;
689 DelegatedScheduledExecutorService(ScheduledExecutorService executor) {
690 super(executor);
691 e = executor;
692 }
693 public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
694 return e.schedule(command, delay, unit);
695 }
696 public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) {
697 return e.schedule(callable, delay, unit);
698 }
699 public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) {
700 return e.scheduleAtFixedRate(command, initialDelay, period, unit);
701 }
702 public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) {
703 return e.scheduleWithFixedDelay(command, initialDelay, delay, unit);
704 }
705 }
706
707 /** Cannot instantiate. */
708 private Executors() {}
709 }