util/concurrent/Executors.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain. Use, modify, and
 * redistribute this code in any way without acknowledgement.
 */

package java.util.concurrent;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;

/**
 * Factory and utility methods for {@link Executor}, {@link
 * ExecutorService}, {@link ThreadFactory}, and {@link Future}
 * classes defined in this package.
 *
 * @since 1.5
 * @author Doug Lea
 */
public class Executors {

    /**
     * A wrapper class that exposes only the ExecutorService methods
     * of an implementation.
     */
    private static class DelegatedExecutorService implements ExecutorService {
        private final ExecutorService e;
        DelegatedExecutorService(ExecutorService executor) { e = executor; }
        public void execute(Runnable command) { e.execute(command); }
        public void shutdown() { e.shutdown(); }
        public List shutdownNow() { return e.shutdownNow(); }
        public boolean isShutdown() { return e.isShutdown(); }
        public boolean isTerminated() { return e.isTerminated(); }
        public boolean awaitTermination(long timeout, TimeUnit unit)
            throws InterruptedException {
            return e.awaitTermination(timeout, unit);
        }
    }
    
    /**
     * A wrapper class that exposes only the ExecutorService and 
     * ScheduleExecutor methods of a ScheduledThreadPoolExecutor.
     */
    private static class DelegatedScheduledExecutorService
            extends DelegatedExecutorService 
            implements ScheduledExecutorService {
        private final ScheduledExecutor e;
        DelegatedScheduledExecutorService(ScheduledExecutorService executor) {
            super(executor);
            e = executor;
        }
        public ScheduledFuture<Boolean> schedule(Runnable command, long delay,  TimeUnit unit) {
            return e.schedule(command, delay, unit);
        }
        public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) {
            return e.schedule(callable, delay, unit);
        }
        public ScheduledFuture<Boolean> scheduleAtFixedRate(Runnable command, long initialDelay,  long period, TimeUnit unit) {
            return e.scheduleAtFixedRate(command, initialDelay, period, unit);
        }
        public ScheduledFuture<Boolean> scheduleWithFixedDelay(Runnable command, long initialDelay,  long delay, TimeUnit unit) {
            return e.scheduleWithFixedDelay(command, initialDelay, delay, unit);
        }
    }

    /**
     * Creates a thread pool that reuses a fixed set of threads
     * operating off a shared unbounded queue. If any thread
     * terminates due to a failure during execution prior to shutdown,
     * a new one will take its place if needed to execute subsequent
     * tasks.
     *
     * @param nThreads the number of threads in the pool
     * @return the newly created thread pool
     */
    public static ExecutorService newFixedThreadPool(int nThreads) {
        return new DelegatedExecutorService
            (new ThreadPoolExecutor(nThreads, nThreads,
                                    0L, TimeUnit.MILLISECONDS,
                                    new LinkedBlockingQueue<Runnable>()));
    }

    /**
     * Creates a thread pool that reuses a fixed set of threads
     * operating off a shared unbounded queue, using the provided
     * ThreadFactory to create new threads when needed.
     *
     * @param nThreads the number of threads in the pool
     * @param threadFactory the factory to use when creating new threads
     * @return the newly created thread pool
     */
    public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {
        return new DelegatedExecutorService
            (new ThreadPoolExecutor(nThreads, nThreads,
                                    0L, TimeUnit.MILLISECONDS,
                                    new LinkedBlockingQueue<Runnable>(),
                                    threadFactory));
    }

    /**
     * Creates an Executor that uses a single worker thread operating
     * off an unbounded queue. (Note however that if this single
     * thread terminates due to a failure during execution prior to
     * shutdown, a new one will take its place if needed to execute
     * subsequent tasks.)  Tasks are guaranteed to execute
     * sequentially, and no more than one task will be active at any
     * given time. This method is equivalent in effect to
     *<tt>new FixedThreadPool(1)</tt>.
     *
     * @return the newly-created single-threaded Executor
     */
    public static ExecutorService newSingleThreadExecutor() {
        return new DelegatedExecutorService
            (new ThreadPoolExecutor(1, 1,
                                    0L, TimeUnit.MILLISECONDS,
                                    new LinkedBlockingQueue<Runnable>()));
    }

    /**
     * Creates an Executor that uses a single worker thread operating
     * off an unbounded queue, and uses the provided ThreadFactory to
     * create new threads when needed.
     * @param threadFactory the factory to use when creating new
     * threads
     *
     * @return the newly-created single-threaded Executor
     */
    public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) {
        return new DelegatedExecutorService
            (new ThreadPoolExecutor(1, 1,
                                    0L, TimeUnit.MILLISECONDS,
                                    new LinkedBlockingQueue<Runnable>(),
                                    threadFactory));
    }

    /**
     * Creates a thread pool that creates new threads as needed, but
     * will reuse previously constructed threads when they are
     * available.  These pools will typically improve the performance
     * of programs that execute many short-lived asynchronous tasks.
     * Calls to <tt>execute</tt> will reuse previously constructed
     * threads if available. If no existing thread is available, a new
     * thread will be created and added to the pool. Threads that have
     * not been used for sixty seconds are terminated and removed from
     * the cache. Thus, a pool that remains idle for long enough will
     * not consume any resources. Note that pools with similar
     * properties but different details (for example, timeout parameters)
     * may be created using {@link ThreadPoolExecutor} constructors.
     *
     * @return the newly created thread pool
     */
    public static ExecutorService newCachedThreadPool() {
        return new DelegatedExecutorService
            (new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                                    60, TimeUnit.SECONDS,
                                    new SynchronousQueue<Runnable>()));
    }

    /**
     * Creates a thread pool that creates new threads as needed, but
     * will reuse previously constructed threads when they are
     * available, and uses the provided
     * ThreadFactory to create new threads when needed.
     * @param threadFactory the factory to use when creating new threads
     * @return the newly created thread pool
     */
    public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
        return new DelegatedExecutorService
            (new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                                    60, TimeUnit.SECONDS,
                                    new SynchronousQueue<Runnable>(),
                                    threadFactory));
    }
   
    /**
     * Creates a thread pool that can schedule commands to run after a 
     * given delay, or to execute periodically.
     * @return a <tt>ScheduledExecutor</tt> that may safely be cast to
     * an <tt>ExecutorService</tt>.
     */
    public static ScheduledExecutorService newScheduledThreadPool() {
        return newScheduledThreadPool(1);
    }
    
    /**
     * Creates a thread pool that can schedule commands to run after a 
     * given delay, or to execute periodically.
     * @param corePoolSize the number of threads to keep in the pool,
     * even if they are idle.
     * @return a <tt>ScheduledExecutor</tt> that may safely be cast to
     * an <tt>ExecutorService</tt>.
     */
    public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
        return new DelegatedScheduledExecutorService
            (new ScheduledThreadPoolExecutor(corePoolSize));
    }

    /**
     * Creates a thread pool that can schedule commands to run after a 
     * given delay, or to execute periodically.
     * @param corePoolSize the number of threads to keep in the pool,
     * even if they are idle.
     * @param threadFactory the factory to use when the executor
     * creates a new thread. 
     * @return a <tt>ScheduledExecutor</tt> that may safely be cast to
     * an <tt>ExecutorService</tt>.
     */
    public static ScheduledExecutorService newScheduledThreadPool(
            int corePoolSize, ThreadFactory threadFactory) {
        return new DelegatedScheduledExecutorService
            (new ScheduledThreadPoolExecutor(corePoolSize, threadFactory));
    }

    /**
     * Executes a Runnable task and returns a Future representing that
     * task.
     *
     * @param executor the Executor to which the task will be submitted
     * @param task the task to submit
     * @return a Future representing pending completion of the task,
     * and whose <tt>get()</tt> method will return <tt>Boolean.TRUE</tt>
     * upon completion
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     */
    public static Future<Boolean> execute(Executor executor, Runnable task) {
        FutureTask<Boolean> ftask = new FutureTask<Boolean>(task, Boolean.TRUE);
        executor.execute(ftask);
        return ftask;
    }

    /**
     * Executes a Runnable task and returns a Future representing that
     * task.
     *
     * @param executor the Executor to which the task will be submitted
     * @param task the task to submit
     * @param value the value which will become the return value of
     * the task upon task completion
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     */
    public static <T> Future<T> execute(Executor executor, Runnable task, T value) {
        FutureTask<T> ftask = new FutureTask<T>(task, value);
        executor.execute(ftask);
        return ftask;
    }

    /**
     * Executes a value-returning task and returns a Future
     * representing the pending results of the task.
     *
     * @param executor the Executor to which the task will be submitted
     * @param task the task to submit
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     */
    public static <T> Future<T> execute(Executor executor, Callable<T> task) {
        FutureTask<T> ftask = new FutureTask<T>(task);
        executor.execute(ftask);
        return ftask;
    }

    /**
     * Executes a Runnable task and blocks until it completes normally
     * or throws an exception.
     *
     * @param executor the Executor to which the task will be submitted
     * @param task the task to submit
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     * @throws ExecutionException if the task encountered an exception
     * while executing
     */
    public static void invoke(Executor executor, Runnable task)
            throws ExecutionException, InterruptedException {
        FutureTask<Boolean> ftask = new FutureTask<Boolean>(task, Boolean.TRUE);
        executor.execute(ftask);
        ftask.get();
    }

    /**
     * Executes a value-returning task and blocks until it returns a
     * value or throws an exception.
     *
     * @param executor the Executor to which the task will be submitted
     * @param task the task to submit
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     * @throws InterruptedException if interrupted while waiting for
     * completion
     * @throws ExecutionException if the task encountered an exception
     * while executing
     */
    public static <T> T invoke(Executor executor, Callable<T> task)
            throws ExecutionException, InterruptedException {
        FutureTask<T> ftask = new FutureTask<T>(task);
        executor.execute(ftask);
        return ftask.get();
    }


    /**
     * Executes a privileged action under the current access control 
     * context and returns a Future representing the pending result 
     * object of that action.
     *
     * @param executor the Executor to which the task will be submitted
     * @param action the action to submit
     * @return a Future representing pending completion of the action
     * @throws RejectedExecutionException if action cannot be scheduled
     * for execution
     */
    public static Future<Object> execute(Executor executor, PrivilegedAction action) {
        Callable<Object> task = new PrivilegedActionAdapter(action);
        FutureTask<Object> future = new PrivilegedFutureTask<Object>(task);
        executor.execute(future);
        return future;
    }

    /**
     * Executes a privileged exception action under the current access control 
     * context and returns a Future representing the pending result 
     * object of that action.
     *
     * @param executor the Executor to which the task will be submitted
     * @param action the action to submit
     * @return a Future representing pending completion of the action
     * @throws RejectedExecutionException if action cannot be scheduled
     * for execution
     */
    public static Future<Object> execute(Executor executor, PrivilegedExceptionAction action) {
        Callable<Object> task = new PrivilegedExceptionActionAdapter(action);
        FutureTask<Object> future = new PrivilegedFutureTask<Object>(task);
        executor.execute(future);
        return future;
    }

    private static class PrivilegedActionAdapter implements Callable<Object> {
        PrivilegedActionAdapter(PrivilegedAction action) {
            this.action = action;
        }
        public Object call () {
            return action.run();
        }
        private final PrivilegedAction action;
    }
    
    private static class PrivilegedExceptionActionAdapter implements Callable<Object> {
        PrivilegedExceptionActionAdapter(PrivilegedExceptionAction action) {
            this.action = action;
        }
        public Object call () throws Exception {
            return action.run();
        }
        private final PrivilegedExceptionAction action;
    }
        
    /**
     * Return a default thread factory used to create new threads.
     * This factory creates all new threads used by an Executor in the
     * same {@link ThreadGroup}. If there is a {@link
     * java.lang.SecurityManager}, it uses the group of {@link
     * System#getSecurityManager}, else the group of the thread
     * invoking this <tt>defaultThreadFactory</tt> method. Each new
     * thread is created as a non-daemon thread with priority
     * <tt>Thread.NORM_PRIORITY</tt>. New threads have names
     * accessible via {@link Thread#getName} of
     * <em>pool-N-thread-M</em>, where <em>N</em> is the sequence
     * number of this factory, and <em>M</em> is the sequence number
     * of the thread created by this factory.
     * @return the thread factory
     */
    public static ThreadFactory defaultThreadFactory() {
        return new DefaultThreadFactory();
    }

    /**
     * Return a thread factory used to create new threads that
     * have the same permissions as the current thread.
     * This factory creates threads with the same settings as {@link
     * Executors#defaultThreadFactory}, additionally setting the
     * AccessControlContext and contextClassLoader of new threads to
     * be the same as the thread invoking this
     * <tt>privilegedThreadFactory</tt> method.  A new
     * <tt>privilegedThreadFactory</tt> can be created within an
     * {@link AccessController#doPrivileged} action setting the
     * current thread's access control context to create threads with
     * the selected permission settings holding within that action.
     *
     * <p> Note that while tasks running within such threads will have
     * the same access control and class loader settings as the
     * current thread, they need not have the same {@link
     * java.lang.ThreadLocal} or {@link
     * java.lang.InheritableThreadLocal} values. If necessary,
     * particular values of thread locals can be set or reset before
     * any task runs in {@link ThreadPoolExecutor} subclasses using
     * {@link ThreadPoolExecutor#beforeExecute}. Also, if it is
     * necessary to initialize worker threads to have the same
     * InheritableThreadLocal settings as some other designated
     * thread, you can create a custom ThreadFactory in which that
     * thread waits for and services requests to create others that
     * will inherit its values.
     *
     * @return the thread factory
     * @throws AccessControlException if the current access control
     * context does not have permission to both get and set context
     * class loader.
     * @see PrivilegedFutureTask
     */
    public static ThreadFactory privilegedThreadFactory() {
        return new PrivilegedThreadFactory();
    }

    static class DefaultThreadFactory implements ThreadFactory {
        static final AtomicInteger poolNumber = new AtomicInteger(1);
        final ThreadGroup group;
        final AtomicInteger threadNumber = new AtomicInteger(1);
        final String namePrefix;

        DefaultThreadFactory() {
            SecurityManager s = System.getSecurityManager();
            group = (s != null)? s.getThreadGroup() :
                                 Thread.currentThread().getThreadGroup();
            namePrefix = "pool-" + 
                          poolNumber.getAndIncrement() + 
                         "-thread-";
        }

        public Thread newThread(Runnable r) {
            Thread t = new Thread(group, r, 
                                  namePrefix + threadNumber.getAndIncrement(),
                                  0);
            if (t.isDaemon())
                t.setDaemon(false);
            if (t.getPriority() != Thread.NORM_PRIORITY)
                t.setPriority(Thread.NORM_PRIORITY);
            return t;
        }
    }

    static class PrivilegedThreadFactory extends DefaultThreadFactory {
        private final ClassLoader ccl;
        private final AccessControlContext acc;

        PrivilegedThreadFactory() {
            super();
            this.ccl = Thread.currentThread().getContextClassLoader();
            this.acc = AccessController.getContext();
            acc.checkPermission(new RuntimePermission("setContextClassLoader"));
        }
        
        public Thread newThread(final Runnable r) {
            return super.newThread(new Runnable() {
                public void run() {
                    AccessController.doPrivileged(new PrivilegedAction() {
                        public Object run() { 
                            Thread.currentThread().setContextClassLoader(ccl);
                            r.run();
                            return null; 
                        }
                    }, acc);
                }
            });
        }
        
    }

        
    /** Cannot instantiate. */
    private Executors() {}
}
Revision:	1.28
Committed:	Sun Dec 7 14:57:46 2003 UTC (20 years, 6 months ago) by tim
Branch:	MAIN
Changes since 1.27:	+7 -6 lines
Log Message:	ScheduledExecutorService for Executors factory method return type
#	User	Rev	Content
1	tim	1.1	/*
2	dl	1.2	* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain. Use, modify, and
4			* redistribute this code in any way without acknowledgement.
5	tim	1.1	*/
6
7			package java.util.concurrent;
8	dl	1.2	import java.util.*;
9	dl	1.22	import java.util.concurrent.atomic.AtomicInteger;
10	tim	1.20	import java.security.AccessControlContext;
11			import java.security.AccessController;
12			import java.security.PrivilegedAction;
13			import java.security.PrivilegedExceptionAction;
14	tim	1.1
15			/**
16	dl	1.18	* Factory and utility methods for {@link Executor}, {@link
17	dl	1.25	* ExecutorService}, {@link ThreadFactory}, and {@link Future}
18			* classes defined in this package.
19	tim	1.1	*
20			* @since 1.5
21	dl	1.12	* @author Doug Lea
22	tim	1.1	*/
23			public class Executors {
24
25			/**
26	dl	1.2	* A wrapper class that exposes only the ExecutorService methods
27			* of an implementation.
28	tim	1.6	*/
29	jozart	1.11	private static class DelegatedExecutorService implements ExecutorService {
30	dl	1.2	private final ExecutorService e;
31			DelegatedExecutorService(ExecutorService executor) { e = executor; }
32			public void execute(Runnable command) { e.execute(command); }
33			public void shutdown() { e.shutdown(); }
34			public List shutdownNow() { return e.shutdownNow(); }
35			public boolean isShutdown() { return e.isShutdown(); }
36			public boolean isTerminated() { return e.isTerminated(); }
37			public boolean awaitTermination(long timeout, TimeUnit unit)
38			throws InterruptedException {
39			return e.awaitTermination(timeout, unit);
40			}
41			}
42	tim	1.26
43			/**
44			* A wrapper class that exposes only the ExecutorService and
45			* ScheduleExecutor methods of a ScheduledThreadPoolExecutor.
46			*/
47	tim	1.27	private static class DelegatedScheduledExecutorService
48	tim	1.28	extends DelegatedExecutorService
49			implements ScheduledExecutorService {
50	tim	1.26	private final ScheduledExecutor e;
51	tim	1.28	DelegatedScheduledExecutorService(ScheduledExecutorService executor) {
52	tim	1.26	super(executor);
53			e = executor;
54			}
55			public ScheduledFuture<Boolean> schedule(Runnable command, long delay, TimeUnit unit) {
56			return e.schedule(command, delay, unit);
57			}
58			public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) {
59			return e.schedule(callable, delay, unit);
60			}
61			public ScheduledFuture<Boolean> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) {
62			return e.scheduleAtFixedRate(command, initialDelay, period, unit);
63			}
64			public ScheduledFuture<Boolean> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) {
65			return e.scheduleWithFixedDelay(command, initialDelay, delay, unit);
66			}
67			}
68	dl	1.2
69			/**
70	tim	1.1	* Creates a thread pool that reuses a fixed set of threads
71	dl	1.16	* operating off a shared unbounded queue. If any thread
72			* terminates due to a failure during execution prior to shutdown,
73			* a new one will take its place if needed to execute subsequent
74			* tasks.
75	tim	1.1	*
76			* @param nThreads the number of threads in the pool
77			* @return the newly created thread pool
78			*/
79	dl	1.2	public static ExecutorService newFixedThreadPool(int nThreads) {
80			return new DelegatedExecutorService
81			(new ThreadPoolExecutor(nThreads, nThreads,
82			0L, TimeUnit.MILLISECONDS,
83	dl	1.3	new LinkedBlockingQueue<Runnable>()));
84	dl	1.2	}
85
86			/**
87			* Creates a thread pool that reuses a fixed set of threads
88			* operating off a shared unbounded queue, using the provided
89			* ThreadFactory to create new threads when needed.
90			*
91			* @param nThreads the number of threads in the pool
92	dl	1.12	* @param threadFactory the factory to use when creating new threads
93	dl	1.2	* @return the newly created thread pool
94			*/
95			public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {
96			return new DelegatedExecutorService
97			(new ThreadPoolExecutor(nThreads, nThreads,
98			0L, TimeUnit.MILLISECONDS,
99	dl	1.3	new LinkedBlockingQueue<Runnable>(),
100	dl	1.14	threadFactory));
101	dl	1.2	}
102
103			/**
104			* Creates an Executor that uses a single worker thread operating
105			* off an unbounded queue. (Note however that if this single
106			* thread terminates due to a failure during execution prior to
107			* shutdown, a new one will take its place if needed to execute
108			* subsequent tasks.) Tasks are guaranteed to execute
109			* sequentially, and no more than one task will be active at any
110	dl	1.16	* given time. This method is equivalent in effect to
111			*<tt>new FixedThreadPool(1)</tt>.
112	dl	1.2	*
113			* @return the newly-created single-threaded Executor
114			*/
115			public static ExecutorService newSingleThreadExecutor() {
116			return new DelegatedExecutorService
117	tim	1.6	(new ThreadPoolExecutor(1, 1,
118	dl	1.2	0L, TimeUnit.MILLISECONDS,
119	dl	1.3	new LinkedBlockingQueue<Runnable>()));
120	dl	1.2	}
121
122			/**
123			* Creates an Executor that uses a single worker thread operating
124			* off an unbounded queue, and uses the provided ThreadFactory to
125			* create new threads when needed.
126	dl	1.12	* @param threadFactory the factory to use when creating new
127	dl	1.2	* threads
128			*
129			* @return the newly-created single-threaded Executor
130			*/
131			public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) {
132			return new DelegatedExecutorService
133	tim	1.6	(new ThreadPoolExecutor(1, 1,
134	dl	1.2	0L, TimeUnit.MILLISECONDS,
135	dl	1.3	new LinkedBlockingQueue<Runnable>(),
136	dl	1.14	threadFactory));
137	tim	1.1	}
138
139			/**
140			* Creates a thread pool that creates new threads as needed, but
141			* will reuse previously constructed threads when they are
142			* available. These pools will typically improve the performance
143			* of programs that execute many short-lived asynchronous tasks.
144			* Calls to <tt>execute</tt> will reuse previously constructed
145			* threads if available. If no existing thread is available, a new
146			* thread will be created and added to the pool. Threads that have
147			* not been used for sixty seconds are terminated and removed from
148			* the cache. Thus, a pool that remains idle for long enough will
149	dl	1.16	* not consume any resources. Note that pools with similar
150			* properties but different details (for example, timeout parameters)
151			* may be created using {@link ThreadPoolExecutor} constructors.
152	tim	1.1	*
153			* @return the newly created thread pool
154			*/
155	dl	1.2	public static ExecutorService newCachedThreadPool() {
156			return new DelegatedExecutorService
157			(new ThreadPoolExecutor(0, Integer.MAX_VALUE,
158			60, TimeUnit.SECONDS,
159	dl	1.3	new SynchronousQueue<Runnable>()));
160	tim	1.1	}
161
162			/**
163	dl	1.2	* Creates a thread pool that creates new threads as needed, but
164			* will reuse previously constructed threads when they are
165	tim	1.6	* available, and uses the provided
166	dl	1.2	* ThreadFactory to create new threads when needed.
167	dl	1.12	* @param threadFactory the factory to use when creating new threads
168	tim	1.1	* @return the newly created thread pool
169			*/
170	dl	1.2	public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
171			return new DelegatedExecutorService
172			(new ThreadPoolExecutor(0, Integer.MAX_VALUE,
173			60, TimeUnit.SECONDS,
174	dl	1.3	new SynchronousQueue<Runnable>(),
175	dl	1.14	threadFactory));
176	tim	1.1	}
177	tim	1.27
178	tim	1.26	/**
179			* Creates a thread pool that can schedule commands to run after a
180			* given delay, or to execute periodically.
181			* @return a <tt>ScheduledExecutor</tt> that may safely be cast to
182			* an <tt>ExecutorService</tt>.
183			*/
184	tim	1.28	public static ScheduledExecutorService newScheduledThreadPool() {
185	tim	1.27	return newScheduledThreadPool(1);
186	tim	1.26	}
187
188			/**
189			* Creates a thread pool that can schedule commands to run after a
190			* given delay, or to execute periodically.
191			* @param corePoolSize the number of threads to keep in the pool,
192			* even if they are idle.
193			* @return a <tt>ScheduledExecutor</tt> that may safely be cast to
194			* an <tt>ExecutorService</tt>.
195			*/
196	tim	1.28	public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
197	tim	1.27	return new DelegatedScheduledExecutorService
198			(new ScheduledThreadPoolExecutor(corePoolSize));
199	tim	1.26	}
200
201			/**
202			* Creates a thread pool that can schedule commands to run after a
203			* given delay, or to execute periodically.
204			* @param corePoolSize the number of threads to keep in the pool,
205			* even if they are idle.
206			* @param threadFactory the factory to use when the executor
207			* creates a new thread.
208			* @return a <tt>ScheduledExecutor</tt> that may safely be cast to
209			* an <tt>ExecutorService</tt>.
210			*/
211	tim	1.28	public static ScheduledExecutorService newScheduledThreadPool(
212			int corePoolSize, ThreadFactory threadFactory) {
213	tim	1.27	return new DelegatedScheduledExecutorService
214			(new ScheduledThreadPoolExecutor(corePoolSize, threadFactory));
215	tim	1.26	}
216	tim	1.1
217			/**
218	dl	1.25	* Executes a Runnable task and returns a Future representing that
219	tim	1.15	* task.
220			*
221			* @param executor the Executor to which the task will be submitted
222			* @param task the task to submit
223	dl	1.25	* @return a Future representing pending completion of the task,
224			* and whose <tt>get()</tt> method will return <tt>Boolean.TRUE</tt>
225			* upon completion
226	tim	1.15	* @throws RejectedExecutionException if task cannot be scheduled
227			* for execution
228			*/
229	dl	1.25	public static Future<Boolean> execute(Executor executor, Runnable task) {
230	tim	1.15	FutureTask<Boolean> ftask = new FutureTask<Boolean>(task, Boolean.TRUE);
231			executor.execute(ftask);
232			return ftask;
233			}
234
235			/**
236	tim	1.1	* Executes a Runnable task and returns a Future representing that
237			* task.
238			*
239			* @param executor the Executor to which the task will be submitted
240			* @param task the task to submit
241			* @param value the value which will become the return value of
242			* the task upon task completion
243	dl	1.5	* @return a Future representing pending completion of the task
244	jozart	1.9	* @throws RejectedExecutionException if task cannot be scheduled
245	tim	1.1	* for execution
246			*/
247	dl	1.5	public static <T> Future<T> execute(Executor executor, Runnable task, T value) {
248	dl	1.10	FutureTask<T> ftask = new FutureTask<T>(task, value);
249	tim	1.1	executor.execute(ftask);
250			return ftask;
251			}
252
253			/**
254			* Executes a value-returning task and returns a Future
255			* representing the pending results of the task.
256			*
257			* @param executor the Executor to which the task will be submitted
258			* @param task the task to submit
259			* @return a Future representing pending completion of the task
260	jozart	1.9	* @throws RejectedExecutionException if task cannot be scheduled
261			* for execution
262	tim	1.1	*/
263	tim	1.15	public static <T> Future<T> execute(Executor executor, Callable<T> task) {
264	dl	1.10	FutureTask<T> ftask = new FutureTask<T>(task);
265	tim	1.1	executor.execute(ftask);
266			return ftask;
267			}
268
269			/**
270			* Executes a Runnable task and blocks until it completes normally
271			* or throws an exception.
272			*
273			* @param executor the Executor to which the task will be submitted
274			* @param task the task to submit
275	jozart	1.9	* @throws RejectedExecutionException if task cannot be scheduled
276			* for execution
277	dl	1.19	* @throws ExecutionException if the task encountered an exception
278			* while executing
279	tim	1.1	*/
280			public static void invoke(Executor executor, Runnable task)
281			throws ExecutionException, InterruptedException {
282	tim	1.13	FutureTask<Boolean> ftask = new FutureTask<Boolean>(task, Boolean.TRUE);
283	tim	1.1	executor.execute(ftask);
284			ftask.get();
285			}
286
287			/**
288			* Executes a value-returning task and blocks until it returns a
289			* value or throws an exception.
290			*
291			* @param executor the Executor to which the task will be submitted
292			* @param task the task to submit
293			* @return a Future representing pending completion of the task
294	jozart	1.9	* @throws RejectedExecutionException if task cannot be scheduled
295			* for execution
296	dl	1.12	* @throws InterruptedException if interrupted while waiting for
297			* completion
298	dl	1.19	* @throws ExecutionException if the task encountered an exception
299			* while executing
300	tim	1.1	*/
301			public static <T> T invoke(Executor executor, Callable<T> task)
302			throws ExecutionException, InterruptedException {
303			FutureTask<T> ftask = new FutureTask<T>(task);
304			executor.execute(ftask);
305			return ftask.get();
306	tim	1.6	}
307
308	tim	1.20
309			/**
310			* Executes a privileged action under the current access control
311			* context and returns a Future representing the pending result
312			* object of that action.
313			*
314			* @param executor the Executor to which the task will be submitted
315			* @param action the action to submit
316			* @return a Future representing pending completion of the action
317			* @throws RejectedExecutionException if action cannot be scheduled
318			* for execution
319			*/
320			public static Future<Object> execute(Executor executor, PrivilegedAction action) {
321			Callable<Object> task = new PrivilegedActionAdapter(action);
322	tim	1.21	FutureTask<Object> future = new PrivilegedFutureTask<Object>(task);
323	tim	1.20	executor.execute(future);
324			return future;
325			}
326
327			/**
328			* Executes a privileged exception action under the current access control
329			* context and returns a Future representing the pending result
330			* object of that action.
331			*
332			* @param executor the Executor to which the task will be submitted
333			* @param action the action to submit
334			* @return a Future representing pending completion of the action
335			* @throws RejectedExecutionException if action cannot be scheduled
336			* for execution
337			*/
338			public static Future<Object> execute(Executor executor, PrivilegedExceptionAction action) {
339			Callable<Object> task = new PrivilegedExceptionActionAdapter(action);
340	tim	1.21	FutureTask<Object> future = new PrivilegedFutureTask<Object>(task);
341	tim	1.20	executor.execute(future);
342			return future;
343			}
344
345			private static class PrivilegedActionAdapter implements Callable<Object> {
346			PrivilegedActionAdapter(PrivilegedAction action) {
347			this.action = action;
348			}
349			public Object call () {
350			return action.run();
351			}
352			private final PrivilegedAction action;
353			}
354
355			private static class PrivilegedExceptionActionAdapter implements Callable<Object> {
356			PrivilegedExceptionActionAdapter(PrivilegedExceptionAction action) {
357			this.action = action;
358			}
359			public Object call () throws Exception {
360			return action.run();
361			}
362			private final PrivilegedExceptionAction action;
363			}
364
365	dl	1.22	/**
366			* Return a default thread factory used to create new threads.
367			* This factory creates all new threads used by an Executor in the
368			* same {@link ThreadGroup}. If there is a {@link
369			* java.lang.SecurityManager}, it uses the group of {@link
370			* System#getSecurityManager}, else the group of the thread
371			* invoking this <tt>defaultThreadFactory</tt> method. Each new
372			* thread is created as a non-daemon thread with priority
373			* <tt>Thread.NORM_PRIORITY</tt>. New threads have names
374			* accessible via {@link Thread#getName} of
375			* <em>pool-N-thread-M</em>, where <em>N</em> is the sequence
376			* number of this factory, and <em>M</em> is the sequence number
377			* of the thread created by this factory.
378			* @return the thread factory
379			*/
380			public static ThreadFactory defaultThreadFactory() {
381	tim	1.26	return new DefaultThreadFactory();
382	dl	1.22	}
383
384			/**
385	dl	1.24	* Return a thread factory used to create new threads that
386			* have the same permissions as the current thread.
387	dl	1.22	* This factory creates threads with the same settings as {@link
388			* Executors#defaultThreadFactory}, additionally setting the
389			* AccessControlContext and contextClassLoader of new threads to
390			* be the same as the thread invoking this
391			* <tt>privilegedThreadFactory</tt> method. A new
392			* <tt>privilegedThreadFactory</tt> can be created within an
393	dl	1.23	* {@link AccessController#doPrivileged} action setting the
394	dl	1.24	* current thread's access control context to create threads with
395	dl	1.23	* the selected permission settings holding within that action.
396	dl	1.22	*
397			* <p> Note that while tasks running within such threads will have
398			* the same access control and class loader settings as the
399			* current thread, they need not have the same {@link
400			* java.lang.ThreadLocal} or {@link
401			* java.lang.InheritableThreadLocal} values. If necessary,
402			* particular values of thread locals can be set or reset before
403			* any task runs in {@link ThreadPoolExecutor} subclasses using
404			* {@link ThreadPoolExecutor#beforeExecute}. Also, if it is
405			* necessary to initialize worker threads to have the same
406			* InheritableThreadLocal settings as some other designated
407			* thread, you can create a custom ThreadFactory in which that
408			* thread waits for and services requests to create others that
409			* will inherit its values.
410			*
411			* @return the thread factory
412			* @throws AccessControlException if the current access control
413			* context does not have permission to both get and set context
414			* class loader.
415			* @see PrivilegedFutureTask
416			*/
417			public static ThreadFactory privilegedThreadFactory() {
418	tim	1.26	return new PrivilegedThreadFactory();
419	dl	1.22	}
420
421			static class DefaultThreadFactory implements ThreadFactory {
422	tim	1.26	static final AtomicInteger poolNumber = new AtomicInteger(1);
423			final ThreadGroup group;
424			final AtomicInteger threadNumber = new AtomicInteger(1);
425			final String namePrefix;
426	dl	1.22
427	tim	1.26	DefaultThreadFactory() {
428	dl	1.22	SecurityManager s = System.getSecurityManager();
429			group = (s != null)? s.getThreadGroup() :
430			Thread.currentThread().getThreadGroup();
431			namePrefix = "pool-" +
432			poolNumber.getAndIncrement() +
433			"-thread-";
434			}
435
436			public Thread newThread(Runnable r) {
437			Thread t = new Thread(group, r,
438			namePrefix + threadNumber.getAndIncrement(),
439			0);
440			if (t.isDaemon())
441			t.setDaemon(false);
442			if (t.getPriority() != Thread.NORM_PRIORITY)
443			t.setPriority(Thread.NORM_PRIORITY);
444			return t;
445			}
446			}
447
448			static class PrivilegedThreadFactory extends DefaultThreadFactory {
449			private final ClassLoader ccl;
450			private final AccessControlContext acc;
451
452			PrivilegedThreadFactory() {
453			super();
454			this.ccl = Thread.currentThread().getContextClassLoader();
455			this.acc = AccessController.getContext();
456			acc.checkPermission(new RuntimePermission("setContextClassLoader"));
457			}
458
459			public Thread newThread(final Runnable r) {
460			return super.newThread(new Runnable() {
461			public void run() {
462			AccessController.doPrivileged(new PrivilegedAction() {
463			public Object run() {
464			Thread.currentThread().setContextClassLoader(ccl);
465			r.run();
466			return null;
467			}
468			}, acc);
469			}
470			});
471			}
472
473			}
474
475	tim	1.20
476	tim	1.15	/** Cannot instantiate. */
477			private Executors() {}
478	tim	1.1	}