1 /* 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /* 26 * This file is available under and governed by the GNU General Public 27 * License version 2 only, as published by the Free Software Foundation. 28 * However, the following notice accompanied the original version of this 29 * file: 30 * 31 * Written by Doug Lea with assistance from members of JCP JSR-166 32 * Expert Group and released to the public domain, as explained at 33 * http://creativecommons.org/publicdomain/zero/1.0/ 34 */ 35 36 package java.util.concurrent; 37 38 import java.security.AccessControlContext; 39 import java.security.AccessControlException; 40 import java.security.AccessController; 41 import java.security.PrivilegedAction; 42 import java.security.PrivilegedActionException; 43 import java.security.PrivilegedExceptionAction; 44 import java.util.Collection; 45 import java.util.List; 46 import java.util.concurrent.atomic.AtomicInteger; 47 import sun.security.util.SecurityConstants; 48 49 // BEGIN android-note 50 // removed security manager docs 51 // END android-note 52 53 /** 54 * Factory and utility methods for {@link Executor}, {@link 55 * ExecutorService}, {@link ScheduledExecutorService}, {@link 56 * ThreadFactory}, and {@link Callable} classes defined in this 57 * package. This class supports the following kinds of methods: 58 * 59 * <ul> 60 * <li>Methods that create and return an {@link ExecutorService} 61 * set up with commonly useful configuration settings. 62 * <li>Methods that create and return a {@link ScheduledExecutorService} 63 * set up with commonly useful configuration settings. 64 * <li>Methods that create and return a "wrapped" ExecutorService, that 65 * disables reconfiguration by making implementation-specific methods 66 * inaccessible. 67 * <li>Methods that create and return a {@link ThreadFactory} 68 * that sets newly created threads to a known state. 69 * <li>Methods that create and return a {@link Callable} 70 * out of other closure-like forms, so they can be used 71 * in execution methods requiring {@code Callable}. 72 * </ul> 73 * 74 * @since 1.5 75 * @author Doug Lea 76 */ 77 public class Executors { 78 79 /** 80 * Creates a thread pool that reuses a fixed number of threads 81 * operating off a shared unbounded queue. At any point, at most 82 * {@code nThreads} threads will be active processing tasks. 83 * If additional tasks are submitted when all threads are active, 84 * they will wait in the queue until a thread is available. 85 * If any thread terminates due to a failure during execution 86 * prior to shutdown, a new one will take its place if needed to 87 * execute subsequent tasks. The threads in the pool will exist 88 * until it is explicitly {@link ExecutorService#shutdown shutdown}. 89 * 90 * @param nThreads the number of threads in the pool 91 * @return the newly created thread pool 92 * @throws IllegalArgumentException if {@code nThreads <= 0} 93 */ newFixedThreadPool(int nThreads)94 public static ExecutorService newFixedThreadPool(int nThreads) { 95 return new ThreadPoolExecutor(nThreads, nThreads, 96 0L, TimeUnit.MILLISECONDS, 97 new LinkedBlockingQueue<Runnable>()); 98 } 99 100 /** 101 * Creates a thread pool that maintains enough threads to support 102 * the given parallelism level, and may use multiple queues to 103 * reduce contention. The parallelism level corresponds to the 104 * maximum number of threads actively engaged in, or available to 105 * engage in, task processing. The actual number of threads may 106 * grow and shrink dynamically. A work-stealing pool makes no 107 * guarantees about the order in which submitted tasks are 108 * executed. 109 * 110 * @param parallelism the targeted parallelism level 111 * @return the newly created thread pool 112 * @throws IllegalArgumentException if {@code parallelism <= 0} 113 * @since 1.8 114 */ newWorkStealingPool(int parallelism)115 public static ExecutorService newWorkStealingPool(int parallelism) { 116 return new ForkJoinPool 117 (parallelism, 118 ForkJoinPool.defaultForkJoinWorkerThreadFactory, 119 null, true); 120 } 121 122 /** 123 * Creates a work-stealing thread pool using the number of 124 * {@linkplain Runtime#availableProcessors available processors} 125 * as its target parallelism level. 126 * 127 * @return the newly created thread pool 128 * @see #newWorkStealingPool(int) 129 * @since 1.8 130 */ newWorkStealingPool()131 public static ExecutorService newWorkStealingPool() { 132 return new ForkJoinPool 133 (Runtime.getRuntime().availableProcessors(), 134 ForkJoinPool.defaultForkJoinWorkerThreadFactory, 135 null, true); 136 } 137 138 /** 139 * Creates a thread pool that reuses a fixed number of threads 140 * operating off a shared unbounded queue, using the provided 141 * ThreadFactory to create new threads when needed. At any point, 142 * at most {@code nThreads} threads will be active processing 143 * tasks. If additional tasks are submitted when all threads are 144 * active, they will wait in the queue until a thread is 145 * available. If any thread terminates due to a failure during 146 * execution prior to shutdown, a new one will take its place if 147 * needed to execute subsequent tasks. The threads in the pool will 148 * exist until it is explicitly {@link ExecutorService#shutdown 149 * shutdown}. 150 * 151 * @param nThreads the number of threads in the pool 152 * @param threadFactory the factory to use when creating new threads 153 * @return the newly created thread pool 154 * @throws NullPointerException if threadFactory is null 155 * @throws IllegalArgumentException if {@code nThreads <= 0} 156 */ newFixedThreadPool(int nThreads, ThreadFactory threadFactory)157 public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) { 158 return new ThreadPoolExecutor(nThreads, nThreads, 159 0L, TimeUnit.MILLISECONDS, 160 new LinkedBlockingQueue<Runnable>(), 161 threadFactory); 162 } 163 164 /** 165 * Creates an Executor that uses a single worker thread operating 166 * off an unbounded queue. (Note however that if this single 167 * thread terminates due to a failure during execution prior to 168 * shutdown, a new one will take its place if needed to execute 169 * subsequent tasks.) Tasks are guaranteed to execute 170 * sequentially, and no more than one task will be active at any 171 * given time. Unlike the otherwise equivalent 172 * {@code newFixedThreadPool(1)} the returned executor is 173 * guaranteed not to be reconfigurable to use additional threads. 174 * 175 * @return the newly created single-threaded Executor 176 */ newSingleThreadExecutor()177 public static ExecutorService newSingleThreadExecutor() { 178 return new FinalizableDelegatedExecutorService 179 (new ThreadPoolExecutor(1, 1, 180 0L, TimeUnit.MILLISECONDS, 181 new LinkedBlockingQueue<Runnable>())); 182 } 183 184 /** 185 * Creates an Executor that uses a single worker thread operating 186 * off an unbounded queue, and uses the provided ThreadFactory to 187 * create a new thread when needed. Unlike the otherwise 188 * equivalent {@code newFixedThreadPool(1, threadFactory)} the 189 * returned executor is guaranteed not to be reconfigurable to use 190 * additional threads. 191 * 192 * @param threadFactory the factory to use when creating new 193 * threads 194 * 195 * @return the newly created single-threaded Executor 196 * @throws NullPointerException if threadFactory is null 197 */ newSingleThreadExecutor(ThreadFactory threadFactory)198 public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) { 199 return new FinalizableDelegatedExecutorService 200 (new ThreadPoolExecutor(1, 1, 201 0L, TimeUnit.MILLISECONDS, 202 new LinkedBlockingQueue<Runnable>(), 203 threadFactory)); 204 } 205 206 /** 207 * Creates a thread pool that creates new threads as needed, but 208 * will reuse previously constructed threads when they are 209 * available. These pools will typically improve the performance 210 * of programs that execute many short-lived asynchronous tasks. 211 * Calls to {@code execute} will reuse previously constructed 212 * threads if available. If no existing thread is available, a new 213 * thread will be created and added to the pool. Threads that have 214 * not been used for sixty seconds are terminated and removed from 215 * the cache. Thus, a pool that remains idle for long enough will 216 * not consume any resources. Note that pools with similar 217 * properties but different details (for example, timeout parameters) 218 * may be created using {@link ThreadPoolExecutor} constructors. 219 * 220 * @return the newly created thread pool 221 */ newCachedThreadPool()222 public static ExecutorService newCachedThreadPool() { 223 return new ThreadPoolExecutor(0, Integer.MAX_VALUE, 224 60L, TimeUnit.SECONDS, 225 new SynchronousQueue<Runnable>()); 226 } 227 228 /** 229 * Creates a thread pool that creates new threads as needed, but 230 * will reuse previously constructed threads when they are 231 * available, and uses the provided 232 * ThreadFactory to create new threads when needed. 233 * @param threadFactory the factory to use when creating new threads 234 * @return the newly created thread pool 235 * @throws NullPointerException if threadFactory is null 236 */ newCachedThreadPool(ThreadFactory threadFactory)237 public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) { 238 return new ThreadPoolExecutor(0, Integer.MAX_VALUE, 239 60L, TimeUnit.SECONDS, 240 new SynchronousQueue<Runnable>(), 241 threadFactory); 242 } 243 244 /** 245 * Creates a single-threaded executor that can schedule commands 246 * to run after a given delay, or to execute periodically. 247 * (Note however that if this single 248 * thread terminates due to a failure during execution prior to 249 * shutdown, a new one will take its place if needed to execute 250 * subsequent tasks.) Tasks are guaranteed to execute 251 * sequentially, and no more than one task will be active at any 252 * given time. Unlike the otherwise equivalent 253 * {@code newScheduledThreadPool(1)} the returned executor is 254 * guaranteed not to be reconfigurable to use additional threads. 255 * @return the newly created scheduled executor 256 */ newSingleThreadScheduledExecutor()257 public static ScheduledExecutorService newSingleThreadScheduledExecutor() { 258 return new DelegatedScheduledExecutorService 259 (new ScheduledThreadPoolExecutor(1)); 260 } 261 262 /** 263 * Creates a single-threaded executor that can schedule commands 264 * to run after a given delay, or to execute periodically. (Note 265 * however that if this single thread terminates due to a failure 266 * during execution prior to shutdown, a new one will take its 267 * place if needed to execute subsequent tasks.) Tasks are 268 * guaranteed to execute sequentially, and no more than one task 269 * will be active at any given time. Unlike the otherwise 270 * equivalent {@code newScheduledThreadPool(1, threadFactory)} 271 * the returned executor is guaranteed not to be reconfigurable to 272 * use additional threads. 273 * @param threadFactory the factory to use when creating new 274 * threads 275 * @return a newly created scheduled executor 276 * @throws NullPointerException if threadFactory is null 277 */ newSingleThreadScheduledExecutor(ThreadFactory threadFactory)278 public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) { 279 return new DelegatedScheduledExecutorService 280 (new ScheduledThreadPoolExecutor(1, threadFactory)); 281 } 282 283 /** 284 * Creates a thread pool that can schedule commands to run after a 285 * given delay, or to execute periodically. 286 * @param corePoolSize the number of threads to keep in the pool, 287 * even if they are idle 288 * @return a newly created scheduled thread pool 289 * @throws IllegalArgumentException if {@code corePoolSize < 0} 290 */ newScheduledThreadPool(int corePoolSize)291 public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) { 292 return new ScheduledThreadPoolExecutor(corePoolSize); 293 } 294 295 /** 296 * Creates a thread pool that can schedule commands to run after a 297 * given delay, or to execute periodically. 298 * @param corePoolSize the number of threads to keep in the pool, 299 * even if they are idle 300 * @param threadFactory the factory to use when the executor 301 * creates a new thread 302 * @return a newly created scheduled thread pool 303 * @throws IllegalArgumentException if {@code corePoolSize < 0} 304 * @throws NullPointerException if threadFactory is null 305 */ newScheduledThreadPool( int corePoolSize, ThreadFactory threadFactory)306 public static ScheduledExecutorService newScheduledThreadPool( 307 int corePoolSize, ThreadFactory threadFactory) { 308 return new ScheduledThreadPoolExecutor(corePoolSize, threadFactory); 309 } 310 311 /** 312 * Returns an object that delegates all defined {@link 313 * ExecutorService} methods to the given executor, but not any 314 * other methods that might otherwise be accessible using 315 * casts. This provides a way to safely "freeze" configuration and 316 * disallow tuning of a given concrete implementation. 317 * @param executor the underlying implementation 318 * @return an {@code ExecutorService} instance 319 * @throws NullPointerException if executor null 320 */ unconfigurableExecutorService(ExecutorService executor)321 public static ExecutorService unconfigurableExecutorService(ExecutorService executor) { 322 if (executor == null) 323 throw new NullPointerException(); 324 return new DelegatedExecutorService(executor); 325 } 326 327 /** 328 * Returns an object that delegates all defined {@link 329 * ScheduledExecutorService} methods to the given executor, but 330 * not any other methods that might otherwise be accessible using 331 * casts. This provides a way to safely "freeze" configuration and 332 * disallow tuning of a given concrete implementation. 333 * @param executor the underlying implementation 334 * @return a {@code ScheduledExecutorService} instance 335 * @throws NullPointerException if executor null 336 */ unconfigurableScheduledExecutorService(ScheduledExecutorService executor)337 public static ScheduledExecutorService unconfigurableScheduledExecutorService(ScheduledExecutorService executor) { 338 if (executor == null) 339 throw new NullPointerException(); 340 return new DelegatedScheduledExecutorService(executor); 341 } 342 343 /** 344 * Returns a default thread factory used to create new threads. 345 * This factory creates all new threads used by an Executor in the 346 * same {@link ThreadGroup}. Each new 347 * thread is created as a non-daemon thread with priority set to 348 * the smaller of {@code Thread.NORM_PRIORITY} and the maximum 349 * priority permitted in the thread group. New threads have names 350 * accessible via {@link Thread#getName} of 351 * <em>pool-N-thread-M</em>, where <em>N</em> is the sequence 352 * number of this factory, and <em>M</em> is the sequence number 353 * of the thread created by this factory. 354 * @return a thread factory 355 */ defaultThreadFactory()356 public static ThreadFactory defaultThreadFactory() { 357 return new DefaultThreadFactory(); 358 } 359 360 /** 361 * Legacy security code; do not use. 362 */ privilegedThreadFactory()363 public static ThreadFactory privilegedThreadFactory() { 364 return new PrivilegedThreadFactory(); 365 } 366 367 /** 368 * Returns a {@link Callable} object that, when 369 * called, runs the given task and returns the given result. This 370 * can be useful when applying methods requiring a 371 * {@code Callable} to an otherwise resultless action. 372 * @param task the task to run 373 * @param result the result to return 374 * @param <T> the type of the result 375 * @return a callable object 376 * @throws NullPointerException if task null 377 */ callable(Runnable task, T result)378 public static <T> Callable<T> callable(Runnable task, T result) { 379 if (task == null) 380 throw new NullPointerException(); 381 return new RunnableAdapter<T>(task, result); 382 } 383 384 /** 385 * Returns a {@link Callable} object that, when 386 * called, runs the given task and returns {@code null}. 387 * @param task the task to run 388 * @return a callable object 389 * @throws NullPointerException if task null 390 */ callable(Runnable task)391 public static Callable<Object> callable(Runnable task) { 392 if (task == null) 393 throw new NullPointerException(); 394 return new RunnableAdapter<Object>(task, null); 395 } 396 397 /** 398 * Returns a {@link Callable} object that, when 399 * called, runs the given privileged action and returns its result. 400 * @param action the privileged action to run 401 * @return a callable object 402 * @throws NullPointerException if action null 403 */ callable(final PrivilegedAction<?> action)404 public static Callable<Object> callable(final PrivilegedAction<?> action) { 405 if (action == null) 406 throw new NullPointerException(); 407 return new Callable<Object>() { 408 public Object call() { return action.run(); }}; 409 } 410 411 /** 412 * Returns a {@link Callable} object that, when 413 * called, runs the given privileged exception action and returns 414 * its result. 415 * @param action the privileged exception action to run 416 * @return a callable object 417 * @throws NullPointerException if action null 418 */ 419 public static Callable<Object> callable(final PrivilegedExceptionAction<?> action) { 420 if (action == null) 421 throw new NullPointerException(); 422 return new Callable<Object>() { 423 public Object call() throws Exception { return action.run(); }}; 424 } 425 426 /** 427 * Legacy security code; do not use. 428 */ 429 public static <T> Callable<T> privilegedCallable(Callable<T> callable) { 430 if (callable == null) 431 throw new NullPointerException(); 432 return new PrivilegedCallable<T>(callable); 433 } 434 435 /** 436 * Legacy security code; do not use. 437 */ 438 public static <T> Callable<T> privilegedCallableUsingCurrentClassLoader(Callable<T> callable) { 439 if (callable == null) 440 throw new NullPointerException(); 441 return new PrivilegedCallableUsingCurrentClassLoader<T>(callable); 442 } 443 444 // Non-public classes supporting the public methods 445 446 /** 447 * A callable that runs given task and returns given result. 448 */ 449 private static final class RunnableAdapter<T> implements Callable<T> { 450 private final Runnable task; 451 private final T result; 452 RunnableAdapter(Runnable task, T result) { 453 this.task = task; 454 this.result = result; 455 } 456 public T call() { 457 task.run(); 458 return result; 459 } 460 } 461 462 /** 463 * A callable that runs under established access control settings. 464 */ 465 private static final class PrivilegedCallable<T> implements Callable<T> { 466 final Callable<T> task; 467 final AccessControlContext acc; 468 469 PrivilegedCallable(Callable<T> task) { 470 this.task = task; 471 this.acc = AccessController.getContext(); 472 } 473 474 public T call() throws Exception { 475 try { 476 return AccessController.doPrivileged( 477 new PrivilegedExceptionAction<T>() { 478 public T run() throws Exception { 479 return task.call(); 480 } 481 }, acc); 482 } catch (PrivilegedActionException e) { 483 throw e.getException(); 484 } 485 } 486 } 487 488 /** 489 * A callable that runs under established access control settings and 490 * current ClassLoader. 491 */ 492 private static final class PrivilegedCallableUsingCurrentClassLoader<T> 493 implements Callable<T> { 494 final Callable<T> task; 495 final AccessControlContext acc; 496 final ClassLoader ccl; 497 498 PrivilegedCallableUsingCurrentClassLoader(Callable<T> task) { 499 // BEGIN Android-removed 500 // SecurityManager sm = System.getSecurityManager(); 501 // if (sm != null) { 502 // // Calls to getContextClassLoader from this class 503 // // never trigger a security check, but we check 504 // // whether our callers have this permission anyways. 505 // sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); 506 507 // // Whether setContextClassLoader turns out to be necessary 508 // // or not, we fail fast if permission is not available. 509 // sm.checkPermission(new RuntimePermission("setContextClassLoader")); 510 // } 511 // END Android-removed 512 this.task = task; 513 this.acc = AccessController.getContext(); 514 this.ccl = Thread.currentThread().getContextClassLoader(); 515 } 516 517 public T call() throws Exception { 518 try { 519 return AccessController.doPrivileged( 520 new PrivilegedExceptionAction<T>() { 521 public T run() throws Exception { 522 Thread t = Thread.currentThread(); 523 ClassLoader cl = t.getContextClassLoader(); 524 if (ccl == cl) { 525 return task.call(); 526 } else { 527 t.setContextClassLoader(ccl); 528 try { 529 return task.call(); 530 } finally { 531 t.setContextClassLoader(cl); 532 } 533 } 534 } 535 }, acc); 536 } catch (PrivilegedActionException e) { 537 throw e.getException(); 538 } 539 } 540 } 541 542 /** 543 * The default thread factory. 544 */ 545 private static class DefaultThreadFactory implements ThreadFactory { 546 private static final AtomicInteger poolNumber = new AtomicInteger(1); 547 private final ThreadGroup group; 548 private final AtomicInteger threadNumber = new AtomicInteger(1); 549 private final String namePrefix; 550 551 DefaultThreadFactory() { 552 SecurityManager s = System.getSecurityManager(); 553 group = (s != null) ? s.getThreadGroup() : 554 Thread.currentThread().getThreadGroup(); 555 namePrefix = "pool-" + 556 poolNumber.getAndIncrement() + 557 "-thread-"; 558 } 559 560 public Thread newThread(Runnable r) { 561 Thread t = new Thread(group, r, 562 namePrefix + threadNumber.getAndIncrement(), 563 0); 564 if (t.isDaemon()) 565 t.setDaemon(false); 566 if (t.getPriority() != Thread.NORM_PRIORITY) 567 t.setPriority(Thread.NORM_PRIORITY); 568 return t; 569 } 570 } 571 572 /** 573 * Thread factory capturing access control context and class loader. 574 */ 575 private static class PrivilegedThreadFactory extends DefaultThreadFactory { 576 final AccessControlContext acc; 577 final ClassLoader ccl; 578 579 PrivilegedThreadFactory() { 580 super(); 581 // BEGIN Android-removed 582 // SecurityManager sm = System.getSecurityManager(); 583 // if (sm != null) { 584 // // Calls to getContextClassLoader from this class 585 // // never trigger a security check, but we check 586 // // whether our callers have this permission anyways. 587 // sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); 588 589 // // Fail fast 590 // sm.checkPermission(new RuntimePermission("setContextClassLoader")); 591 // } 592 // END Android-removed 593 this.acc = AccessController.getContext(); 594 this.ccl = Thread.currentThread().getContextClassLoader(); 595 } 596 597 public Thread newThread(final Runnable r) { 598 return super.newThread(new Runnable() { 599 public void run() { 600 AccessController.doPrivileged(new PrivilegedAction<Void>() { 601 public Void run() { 602 Thread.currentThread().setContextClassLoader(ccl); 603 r.run(); 604 return null; 605 } 606 }, acc); 607 } 608 }); 609 } 610 } 611 612 /** 613 * A wrapper class that exposes only the ExecutorService methods 614 * of an ExecutorService implementation. 615 */ 616 private static class DelegatedExecutorService 617 extends AbstractExecutorService { 618 private final ExecutorService e; 619 DelegatedExecutorService(ExecutorService executor) { e = executor; } 620 public void execute(Runnable command) { e.execute(command); } 621 public void shutdown() { e.shutdown(); } 622 public List<Runnable> shutdownNow() { return e.shutdownNow(); } 623 public boolean isShutdown() { return e.isShutdown(); } 624 public boolean isTerminated() { return e.isTerminated(); } 625 public boolean awaitTermination(long timeout, TimeUnit unit) 626 throws InterruptedException { 627 return e.awaitTermination(timeout, unit); 628 } 629 public Future<?> submit(Runnable task) { 630 return e.submit(task); 631 } 632 public <T> Future<T> submit(Callable<T> task) { 633 return e.submit(task); 634 } 635 public <T> Future<T> submit(Runnable task, T result) { 636 return e.submit(task, result); 637 } 638 public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) 639 throws InterruptedException { 640 return e.invokeAll(tasks); 641 } 642 public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, 643 long timeout, TimeUnit unit) 644 throws InterruptedException { 645 return e.invokeAll(tasks, timeout, unit); 646 } 647 public <T> T invokeAny(Collection<? extends Callable<T>> tasks) 648 throws InterruptedException, ExecutionException { 649 return e.invokeAny(tasks); 650 } 651 public <T> T invokeAny(Collection<? extends Callable<T>> tasks, 652 long timeout, TimeUnit unit) 653 throws InterruptedException, ExecutionException, TimeoutException { 654 return e.invokeAny(tasks, timeout, unit); 655 } 656 } 657 658 private static class FinalizableDelegatedExecutorService 659 extends DelegatedExecutorService { 660 FinalizableDelegatedExecutorService(ExecutorService executor) { 661 super(executor); 662 } 663 protected void finalize() { 664 super.shutdown(); 665 } 666 } 667 668 /** 669 * A wrapper class that exposes only the ScheduledExecutorService 670 * methods of a ScheduledExecutorService implementation. 671 */ 672 private static class DelegatedScheduledExecutorService 673 extends DelegatedExecutorService 674 implements ScheduledExecutorService { 675 private final ScheduledExecutorService e; 676 DelegatedScheduledExecutorService(ScheduledExecutorService executor) { 677 super(executor); 678 e = executor; 679 } 680 public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) { 681 return e.schedule(command, delay, unit); 682 } 683 public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) { 684 return e.schedule(callable, delay, unit); 685 } 686 public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) { 687 return e.scheduleAtFixedRate(command, initialDelay, period, unit); 688 } 689 public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) { 690 return e.scheduleWithFixedDelay(command, initialDelay, delay, unit); 691 } 692 } 693 694 /** Cannot instantiate. */ 695 private Executors() {} 696 } 697