66 * </ul>
67 *
68 * @since 1.5
69 * @author Doug Lea
70 */
71 public class Executors {
72
73 /**
74 * Creates a thread pool that reuses a fixed number of threads
75 * operating off a shared unbounded queue. At any point, at most
76 * <tt>nThreads</tt> threads will be active processing tasks.
77 * If additional tasks are submitted when all threads are active,
78 * they will wait in the queue until a thread is available.
79 * If any thread terminates due to a failure during execution
80 * prior to shutdown, a new one will take its place if needed to
81 * execute subsequent tasks. The threads in the pool will exist
82 * until it is explicitly {@link ExecutorService#shutdown shutdown}.
83 *
84 * @param nThreads the number of threads in the pool
85 * @return the newly created thread pool
86 * @throws IllegalArgumentException if <tt>nThreads <= 0</tt>
87 */
88 public static ExecutorService newFixedThreadPool(int nThreads) {
89 return new ThreadPoolExecutor(nThreads, nThreads,
90 0L, TimeUnit.MILLISECONDS,
91 new LinkedBlockingQueue<Runnable>());
92 }
93
94 /**
95 * Creates a thread pool that reuses a fixed number of threads
96 * operating off a shared unbounded queue, using the provided
97 * ThreadFactory to create new threads when needed. At any point,
98 * at most <tt>nThreads</tt> threads will be active processing
99 * tasks. If additional tasks are submitted when all threads are
100 * active, they will wait in the queue until a thread is
101 * available. If any thread terminates due to a failure during
102 * execution prior to shutdown, a new one will take its place if
103 * needed to execute subsequent tasks. The threads in the pool will
104 * exist until it is explicitly {@link ExecutorService#shutdown
105 * shutdown}.
106 *
107 * @param nThreads the number of threads in the pool
108 * @param threadFactory the factory to use when creating new threads
109 * @return the newly created thread pool
110 * @throws NullPointerException if threadFactory is null
111 * @throws IllegalArgumentException if <tt>nThreads <= 0</tt>
112 */
113 public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {
114 return new ThreadPoolExecutor(nThreads, nThreads,
115 0L, TimeUnit.MILLISECONDS,
116 new LinkedBlockingQueue<Runnable>(),
117 threadFactory);
118 }
119
120 /**
121 * Creates an Executor that uses a single worker thread operating
122 * off an unbounded queue. (Note however that if this single
123 * thread terminates due to a failure during execution prior to
124 * shutdown, a new one will take its place if needed to execute
125 * subsequent tasks.) Tasks are guaranteed to execute
126 * sequentially, and no more than one task will be active at any
127 * given time. Unlike the otherwise equivalent
128 * <tt>newFixedThreadPool(1)</tt> the returned executor is
129 * guaranteed not to be reconfigurable to use additional threads.
130 *
131 * @return the newly created single-threaded Executor
225 * will be active at any given time. Unlike the otherwise
226 * equivalent <tt>newScheduledThreadPool(1, threadFactory)</tt>
227 * the returned executor is guaranteed not to be reconfigurable to
228 * use additional threads.
229 * @param threadFactory the factory to use when creating new
230 * threads
231 * @return a newly created scheduled executor
232 * @throws NullPointerException if threadFactory is null
233 */
234 public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) {
235 return new DelegatedScheduledExecutorService
236 (new ScheduledThreadPoolExecutor(1, threadFactory));
237 }
238
239 /**
240 * Creates a thread pool that can schedule commands to run after a
241 * given delay, or to execute periodically.
242 * @param corePoolSize the number of threads to keep in the pool,
243 * even if they are idle.
244 * @return a newly created scheduled thread pool
245 * @throws IllegalArgumentException if <tt>corePoolSize < 0</tt>
246 */
247 public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
248 return new ScheduledThreadPoolExecutor(corePoolSize);
249 }
250
251 /**
252 * Creates a thread pool that can schedule commands to run after a
253 * given delay, or to execute periodically.
254 * @param corePoolSize the number of threads to keep in the pool,
255 * even if they are idle.
256 * @param threadFactory the factory to use when the executor
257 * creates a new thread.
258 * @return a newly created scheduled thread pool
259 * @throws IllegalArgumentException if <tt>corePoolSize < 0</tt>
260 * @throws NullPointerException if threadFactory is null
261 */
262 public static ScheduledExecutorService newScheduledThreadPool(
263 int corePoolSize, ThreadFactory threadFactory) {
264 return new ScheduledThreadPoolExecutor(corePoolSize, threadFactory);
265 }
266
267
268 /**
269 * Returns an object that delegates all defined {@link
270 * ExecutorService} methods to the given executor, but not any
271 * other methods that might otherwise be accessible using
272 * casts. This provides a way to safely "freeze" configuration and
273 * disallow tuning of a given concrete implementation.
274 * @param executor the underlying implementation
275 * @return an <tt>ExecutorService</tt> instance
276 * @throws NullPointerException if executor null
277 */
278 public static ExecutorService unconfigurableExecutorService(ExecutorService executor) {
279 if (executor == null)
545 }
546 }
547 }, acc);
548 } catch (PrivilegedActionException e) {
549 throw e.getException();
550 }
551 }
552 }
553
554 /**
555 * The default thread factory
556 */
557 static class DefaultThreadFactory implements ThreadFactory {
558 private static final AtomicInteger poolNumber = new AtomicInteger(1);
559 private final ThreadGroup group;
560 private final AtomicInteger threadNumber = new AtomicInteger(1);
561 private final String namePrefix;
562
563 DefaultThreadFactory() {
564 SecurityManager s = System.getSecurityManager();
565 group = (s != null)? s.getThreadGroup() :
566 Thread.currentThread().getThreadGroup();
567 namePrefix = "pool-" +
568 poolNumber.getAndIncrement() +
569 "-thread-";
570 }
571
572 public Thread newThread(Runnable r) {
573 Thread t = new Thread(group, r,
574 namePrefix + threadNumber.getAndIncrement(),
575 0);
576 if (t.isDaemon())
577 t.setDaemon(false);
578 if (t.getPriority() != Thread.NORM_PRIORITY)
579 t.setPriority(Thread.NORM_PRIORITY);
580 return t;
581 }
582 }
583
584 /**
585 * Thread factory capturing access control context and class loader
|
66 * </ul>
67 *
68 * @since 1.5
69 * @author Doug Lea
70 */
71 public class Executors {
72
73 /**
74 * Creates a thread pool that reuses a fixed number of threads
75 * operating off a shared unbounded queue. At any point, at most
76 * <tt>nThreads</tt> threads will be active processing tasks.
77 * If additional tasks are submitted when all threads are active,
78 * they will wait in the queue until a thread is available.
79 * If any thread terminates due to a failure during execution
80 * prior to shutdown, a new one will take its place if needed to
81 * execute subsequent tasks. The threads in the pool will exist
82 * until it is explicitly {@link ExecutorService#shutdown shutdown}.
83 *
84 * @param nThreads the number of threads in the pool
85 * @return the newly created thread pool
86 * @throws IllegalArgumentException if {@code nThreads <= 0}
87 */
88 public static ExecutorService newFixedThreadPool(int nThreads) {
89 return new ThreadPoolExecutor(nThreads, nThreads,
90 0L, TimeUnit.MILLISECONDS,
91 new LinkedBlockingQueue<Runnable>());
92 }
93
94 /**
95 * Creates a thread pool that reuses a fixed number of threads
96 * operating off a shared unbounded queue, using the provided
97 * ThreadFactory to create new threads when needed. At any point,
98 * at most <tt>nThreads</tt> threads will be active processing
99 * tasks. If additional tasks are submitted when all threads are
100 * active, they will wait in the queue until a thread is
101 * available. If any thread terminates due to a failure during
102 * execution prior to shutdown, a new one will take its place if
103 * needed to execute subsequent tasks. The threads in the pool will
104 * exist until it is explicitly {@link ExecutorService#shutdown
105 * shutdown}.
106 *
107 * @param nThreads the number of threads in the pool
108 * @param threadFactory the factory to use when creating new threads
109 * @return the newly created thread pool
110 * @throws NullPointerException if threadFactory is null
111 * @throws IllegalArgumentException if {@code nThreads <= 0}
112 */
113 public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {
114 return new ThreadPoolExecutor(nThreads, nThreads,
115 0L, TimeUnit.MILLISECONDS,
116 new LinkedBlockingQueue<Runnable>(),
117 threadFactory);
118 }
119
120 /**
121 * Creates an Executor that uses a single worker thread operating
122 * off an unbounded queue. (Note however that if this single
123 * thread terminates due to a failure during execution prior to
124 * shutdown, a new one will take its place if needed to execute
125 * subsequent tasks.) Tasks are guaranteed to execute
126 * sequentially, and no more than one task will be active at any
127 * given time. Unlike the otherwise equivalent
128 * <tt>newFixedThreadPool(1)</tt> the returned executor is
129 * guaranteed not to be reconfigurable to use additional threads.
130 *
131 * @return the newly created single-threaded Executor
225 * will be active at any given time. Unlike the otherwise
226 * equivalent <tt>newScheduledThreadPool(1, threadFactory)</tt>
227 * the returned executor is guaranteed not to be reconfigurable to
228 * use additional threads.
229 * @param threadFactory the factory to use when creating new
230 * threads
231 * @return a newly created scheduled executor
232 * @throws NullPointerException if threadFactory is null
233 */
234 public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) {
235 return new DelegatedScheduledExecutorService
236 (new ScheduledThreadPoolExecutor(1, threadFactory));
237 }
238
239 /**
240 * Creates a thread pool that can schedule commands to run after a
241 * given delay, or to execute periodically.
242 * @param corePoolSize the number of threads to keep in the pool,
243 * even if they are idle.
244 * @return a newly created scheduled thread pool
245 * @throws IllegalArgumentException if {@code corePoolSize < 0}
246 */
247 public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
248 return new ScheduledThreadPoolExecutor(corePoolSize);
249 }
250
251 /**
252 * Creates a thread pool that can schedule commands to run after a
253 * given delay, or to execute periodically.
254 * @param corePoolSize the number of threads to keep in the pool,
255 * even if they are idle.
256 * @param threadFactory the factory to use when the executor
257 * creates a new thread.
258 * @return a newly created scheduled thread pool
259 * @throws IllegalArgumentException if {@code corePoolSize < 0}
260 * @throws NullPointerException if threadFactory is null
261 */
262 public static ScheduledExecutorService newScheduledThreadPool(
263 int corePoolSize, ThreadFactory threadFactory) {
264 return new ScheduledThreadPoolExecutor(corePoolSize, threadFactory);
265 }
266
267
268 /**
269 * Returns an object that delegates all defined {@link
270 * ExecutorService} methods to the given executor, but not any
271 * other methods that might otherwise be accessible using
272 * casts. This provides a way to safely "freeze" configuration and
273 * disallow tuning of a given concrete implementation.
274 * @param executor the underlying implementation
275 * @return an <tt>ExecutorService</tt> instance
276 * @throws NullPointerException if executor null
277 */
278 public static ExecutorService unconfigurableExecutorService(ExecutorService executor) {
279 if (executor == null)
545 }
546 }
547 }, acc);
548 } catch (PrivilegedActionException e) {
549 throw e.getException();
550 }
551 }
552 }
553
554 /**
555 * The default thread factory
556 */
557 static class DefaultThreadFactory implements ThreadFactory {
558 private static final AtomicInteger poolNumber = new AtomicInteger(1);
559 private final ThreadGroup group;
560 private final AtomicInteger threadNumber = new AtomicInteger(1);
561 private final String namePrefix;
562
563 DefaultThreadFactory() {
564 SecurityManager s = System.getSecurityManager();
565 group = (s != null) ? s.getThreadGroup() :
566 Thread.currentThread().getThreadGroup();
567 namePrefix = "pool-" +
568 poolNumber.getAndIncrement() +
569 "-thread-";
570 }
571
572 public Thread newThread(Runnable r) {
573 Thread t = new Thread(group, r,
574 namePrefix + threadNumber.getAndIncrement(),
575 0);
576 if (t.isDaemon())
577 t.setDaemon(false);
578 if (t.getPriority() != Thread.NORM_PRIORITY)
579 t.setPriority(Thread.NORM_PRIORITY);
580 return t;
581 }
582 }
583
584 /**
585 * Thread factory capturing access control context and class loader
|