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	/*
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* Written by Doug Lea with assistance from members of JCP JSR-166
	* Expert Group and released to the public domain, as explained at
	* http://creativecommons.org/publicdomain/zero/1.0/
	*/

	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;
	import java.security.PrivilegedActionException;
	import java.security.AccessControlException;
	import sun.security.util.SecurityConstants;

	/**
	* Factory and utility methods for {@link Executor}, {@link
	* ExecutorService}, {@link ScheduledExecutorService}, {@link
	* ThreadFactory}, and {@link Callable} classes defined in this
	* package. This class supports the following kinds of methods:
	*
	* <ul>
	* <li> Methods that create and return an {@link ExecutorService}
	* set up with commonly useful configuration settings.
	* <li> Methods that create and return a {@link ScheduledExecutorService}
	* set up with commonly useful configuration settings.
	* <li> Methods that create and return a "wrapped" ExecutorService, that
	* disables reconfiguration by making implementation-specific methods
	* inaccessible.
	* <li> Methods that create and return a {@link ThreadFactory}
	* that sets newly created threads to a known state.
	* <li> Methods that create and return a {@link Callable}
	* out of other closure-like forms, so they can be used
	* in execution methods requiring {@code Callable}.
	* </ul>
	*
	* @since 1.5
	* @author Doug Lea
	*/
	public class Executors {

	/**
	* Creates a thread pool that reuses a fixed number of threads
	* operating off a shared unbounded queue. At any point, at most
	* {@code nThreads} threads will be active processing tasks.
	* If additional tasks are submitted when all threads are active,
	* they will wait in the queue until a thread is available.
	* 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. The threads in the pool will exist
	* until it is explicitly {@link ExecutorService#shutdown shutdown}.
	*
	* @param nThreads the number of threads in the pool
	* @return the newly created thread pool
	* @throws IllegalArgumentException if {@code nThreads <= 0}
	*/
	public static ExecutorService newFixedThreadPool(int nThreads) {
	return new ThreadPoolExecutor(nThreads, nThreads,
	0L, TimeUnit.MILLISECONDS,
	new LinkedBlockingQueue<Runnable>());
	}

	/**
	* Creates a thread pool that maintains enough threads to support
	* the given parallelism level, and may use multiple queues to
	* reduce contention. The parallelism level corresponds to the
	* maximum number of threads actively engaged in, or available to
	* engage in, task processing. The actual number of threads may
	* grow and shrink dynamically. A work-stealing pool makes no
	* guarantees about the order in which submitted tasks are
	* executed.
	*
	* @param parallelism the targeted parallelism level
	* @return the newly created thread pool
	* @throws IllegalArgumentException if {@code parallelism <= 0}
	* @since 1.8
	*/
	public static ExecutorService newWorkStealingPool(int parallelism) {
	return new ForkJoinPool
	(parallelism,
	ForkJoinPool.defaultForkJoinWorkerThreadFactory,
	null, true);
	}

	/**
	* Creates a work-stealing thread pool using all
	* {@link Runtime#availableProcessors available processors}
	* as its target parallelism level.
	* @return the newly created thread pool
	* @see #newWorkStealingPool(int)
	* @since 1.8
	*/
	public static ExecutorService newWorkStealingPool() {
	return new ForkJoinPool
	(Runtime.getRuntime().availableProcessors(),
	ForkJoinPool.defaultForkJoinWorkerThreadFactory,
	null, true);
	}

	/**
	* Creates a thread pool that reuses a fixed number of threads
	* operating off a shared unbounded queue, using the provided
	* ThreadFactory to create new threads when needed. At any point,
	* at most {@code nThreads} threads will be active processing
	* tasks. If additional tasks are submitted when all threads are
	* active, they will wait in the queue until a thread is
	* available. 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. The threads in the pool will
	* exist until it is explicitly {@link ExecutorService#shutdown
	* shutdown}.
	*
	* @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
	* @throws NullPointerException if threadFactory is null
	* @throws IllegalArgumentException if {@code nThreads <= 0}
	*/
	public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {
	return 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. Unlike the otherwise equivalent
	* {@code newFixedThreadPool(1)} the returned executor is
	* guaranteed not to be reconfigurable to use additional threads.
	*
	* @return the newly created single-threaded Executor
	*/
	public static ExecutorService newSingleThreadExecutor() {
	return new FinalizableDelegatedExecutorService
	(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 a new thread when needed. Unlike the otherwise
	* equivalent {@code newFixedThreadPool(1, threadFactory)} the
	* returned executor is guaranteed not to be reconfigurable to use
	* additional threads.
	*
	* @param threadFactory the factory to use when creating new
	* threads
	*
	* @return the newly created single-threaded Executor
	* @throws NullPointerException if threadFactory is null
	*/
	public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) {
	return new FinalizableDelegatedExecutorService
	(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 {@code execute} 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 ThreadPoolExecutor(0, Integer.MAX_VALUE,
	60L, 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
	* @throws NullPointerException if threadFactory is null
	*/
	public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
	return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
	60L, TimeUnit.SECONDS,
	new SynchronousQueue<Runnable>(),
	threadFactory);
	}

	/**
	* Creates a single-threaded executor that can schedule commands
	* to run after a given delay, or to execute periodically.
	* (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. Unlike the otherwise equivalent
	* {@code newScheduledThreadPool(1)} the returned executor is
	* guaranteed not to be reconfigurable to use additional threads.
	* @return the newly created scheduled executor
	*/
	public static ScheduledExecutorService newSingleThreadScheduledExecutor() {
	return new DelegatedScheduledExecutorService
	(new ScheduledThreadPoolExecutor(1));
	}

	/**
	* Creates a single-threaded executor that can schedule commands
	* to run after a given delay, or to execute periodically. (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. Unlike the otherwise
	* equivalent {@code newScheduledThreadPool(1, threadFactory)}
	* the returned executor is guaranteed not to be reconfigurable to
	* use additional threads.
	* @param threadFactory the factory to use when creating new
	* threads
	* @return a newly created scheduled executor
	* @throws NullPointerException if threadFactory is null
	*/
	public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) {
	return new DelegatedScheduledExecutorService
	(new ScheduledThreadPoolExecutor(1, threadFactory));
	}

	/**
	* 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 newly created scheduled thread pool
	* @throws IllegalArgumentException if {@code corePoolSize < 0}
	*/
	public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
	return 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 newly created scheduled thread pool
	* @throws IllegalArgumentException if {@code corePoolSize < 0}
	* @throws NullPointerException if threadFactory is null
	*/
	public static ScheduledExecutorService newScheduledThreadPool(
	int corePoolSize, ThreadFactory threadFactory) {
	return new ScheduledThreadPoolExecutor(corePoolSize, threadFactory);
	}

	/**
	* Returns an object that delegates all defined {@link
	* ExecutorService} methods to the given executor, but not any
	* other methods that might otherwise be accessible using
	* casts. This provides a way to safely "freeze" configuration and
	* disallow tuning of a given concrete implementation.
	* @param executor the underlying implementation
	* @return an {@code ExecutorService} instance
	* @throws NullPointerException if executor null
	*/
	public static ExecutorService unconfigurableExecutorService(ExecutorService executor) {
	if (executor == null)
	throw new NullPointerException();
	return new DelegatedExecutorService(executor);
	}

	/**
	* Returns an object that delegates all defined {@link
	* ScheduledExecutorService} methods to the given executor, but
	* not any other methods that might otherwise be accessible using
	* casts. This provides a way to safely "freeze" configuration and
	* disallow tuning of a given concrete implementation.
	* @param executor the underlying implementation
	* @return a {@code ScheduledExecutorService} instance
	* @throws NullPointerException if executor null
	*/
	public static ScheduledExecutorService unconfigurableScheduledExecutorService(ScheduledExecutorService executor) {
	if (executor == null)
	throw new NullPointerException();
	return new DelegatedScheduledExecutorService(executor);
	}

	/**
	* Returns 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 {@code defaultThreadFactory} method. Each new
	* thread is created as a non-daemon thread with priority set to
	* the smaller of {@code Thread.NORM_PRIORITY} and the maximum
	* priority permitted in the thread group. 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 a thread factory
	*/
	public static ThreadFactory defaultThreadFactory() {
	return new DefaultThreadFactory();
	}

	/**
	* Returns 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
	* {@code privilegedThreadFactory} method. A new
	* {@code privilegedThreadFactory} can be created within an
	* {@link AccessController#doPrivileged 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(Thread, Runnable)}.
	* 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 a thread factory
	* @throws AccessControlException if the current access control
	* context does not have permission to both get and set context
	* class loader
	*/
	public static ThreadFactory privilegedThreadFactory() {
	return new PrivilegedThreadFactory();
	}

	/**
	* Returns a {@link Callable} object that, when
	* called, runs the given task and returns the given result. This
	* can be useful when applying methods requiring a
	* {@code Callable} to an otherwise resultless action.
	* @param task the task to run
	* @param result the result to return
	* @param <T> the type of the result
	* @return a callable object
	* @throws NullPointerException if task null
	*/
	public static <T> Callable<T> callable(Runnable task, T result) {
	if (task == null)
	throw new NullPointerException();
	return new RunnableAdapter<T>(task, result);
	}

	/**
	* Returns a {@link Callable} object that, when
	* called, runs the given task and returns {@code null}.
	* @param task the task to run
	* @return a callable object
	* @throws NullPointerException if task null
	*/
	public static Callable<Object> callable(Runnable task) {
	if (task == null)
	throw new NullPointerException();
	return new RunnableAdapter<Object>(task, null);
	}

	/**
	* Returns a {@link Callable} object that, when
	* called, runs the given privileged action and returns its result.
	* @param action the privileged action to run
	* @return a callable object
	* @throws NullPointerException if action null
	*/
	public static Callable<Object> callable(final PrivilegedAction<?> action) {
	if (action == null)
	throw new NullPointerException();
	return new Callable<Object>() {
	public Object call() { return action.run(); }};
	}

	/**
	* Returns a {@link Callable} object that, when
	* called, runs the given privileged exception action and returns
	* its result.
	* @param action the privileged exception action to run
	* @return a callable object
	* @throws NullPointerException if action null
	*/
	public static Callable<Object> callable(final PrivilegedExceptionAction<?> action) {
	if (action == null)
	throw new NullPointerException();
	return new Callable<Object>() {
	public Object call() throws Exception { return action.run(); }};
	}

	/**
	* Returns a {@link Callable} object that will, when called,
	* execute the given {@code callable} under the current access
	* control context. This method should normally be invoked within
	* an {@link AccessController#doPrivileged AccessController.doPrivileged}
	* action to create callables that will, if possible, execute
	* under the selected permission settings holding within that
	* action; or if not possible, throw an associated {@link
	* AccessControlException}.
	* @param callable the underlying task
	* @param <T> the type of the callable's result
	* @return a callable object
	* @throws NullPointerException if callable null
	*/
	public static <T> Callable<T> privilegedCallable(Callable<T> callable) {
	if (callable == null)
	throw new NullPointerException();
	return new PrivilegedCallable<T>(callable);
	}

	/**
	* Returns a {@link Callable} object that will, when called,
	* execute the given {@code callable} under the current access
	* control context, with the current context class loader as the
	* context class loader. This method should normally be invoked
	* within an
	* {@link AccessController#doPrivileged AccessController.doPrivileged}
	* action to create callables that will, if possible, execute
	* under the selected permission settings holding within that
	* action; or if not possible, throw an associated {@link
	* AccessControlException}.
	*
	* @param callable the underlying task
	* @param <T> the type of the callable's result
	* @return a callable object
	* @throws NullPointerException if callable null
	* @throws AccessControlException if the current access control
	* context does not have permission to both set and get context
	* class loader
	*/
	public static <T> Callable<T> privilegedCallableUsingCurrentClassLoader(Callable<T> callable) {
	if (callable == null)
	throw new NullPointerException();
	return new PrivilegedCallableUsingCurrentClassLoader<T>(callable);
	}

	// Non-public classes supporting the public methods

	/**
	* A callable that runs given task and returns given result
	*/
	static final class RunnableAdapter<T> implements Callable<T> {
	final Runnable task;
	final T result;
	RunnableAdapter(Runnable task, T result) {
	this.task = task;
	this.result = result;
	}
	public T call() {
	task.run();
	return result;
	}
	}

	/**
	* A callable that runs under established access control settings
	*/
	static final class PrivilegedCallable<T> implements Callable<T> {
	private final Callable<T> task;
	private final AccessControlContext acc;

	PrivilegedCallable(Callable<T> task) {
	this.task = task;
	this.acc = AccessController.getContext();
	}

	public T call() throws Exception {
	try {
	return AccessController.doPrivileged(
	new PrivilegedExceptionAction<T>() {
	public T run() throws Exception {
	return task.call();
	}
	}, acc);
	} catch (PrivilegedActionException e) {
	throw e.getException();
	}
	}
	}

	/**
	* A callable that runs under established access control settings and
	* current ClassLoader
	*/
	static final class PrivilegedCallableUsingCurrentClassLoader<T> implements Callable<T> {
	private final Callable<T> task;
	private final AccessControlContext acc;
	private final ClassLoader ccl;

	PrivilegedCallableUsingCurrentClassLoader(Callable<T> task) {
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	// Calls to getContextClassLoader from this class
	// never trigger a security check, but we check
	// whether our callers have this permission anyways.
	sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);

	// Whether setContextClassLoader turns out to be necessary
	// or not, we fail fast if permission is not available.
	sm.checkPermission(new RuntimePermission("setContextClassLoader"));
	}
	this.task = task;
	this.acc = AccessController.getContext();
	this.ccl = Thread.currentThread().getContextClassLoader();
	}

	public T call() throws Exception {
	try {
	return AccessController.doPrivileged(
	new PrivilegedExceptionAction<T>() {
	public T run() throws Exception {
	Thread t = Thread.currentThread();
	ClassLoader cl = t.getContextClassLoader();
	if (ccl == cl) {
	return task.call();
	} else {
	t.setContextClassLoader(ccl);
	try {
	return task.call();
	} finally {
	t.setContextClassLoader(cl);
	}
	}
	}
	}, acc);
	} catch (PrivilegedActionException e) {
	throw e.getException();
	}
	}
	}

	/**
	* The default thread factory
	*/
	static class DefaultThreadFactory implements ThreadFactory {
	private static final AtomicInteger poolNumber = new AtomicInteger(1);
	private final ThreadGroup group;
	private final AtomicInteger threadNumber = new AtomicInteger(1);
	private 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;
	}
	}

	/**
	* Thread factory capturing access control context and class loader
	*/
	static class PrivilegedThreadFactory extends DefaultThreadFactory {
	private final AccessControlContext acc;
	private final ClassLoader ccl;

	PrivilegedThreadFactory() {
	super();
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	// Calls to getContextClassLoader from this class
	// never trigger a security check, but we check
	// whether our callers have this permission anyways.
	sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);

	// Fail fast
	sm.checkPermission(new RuntimePermission("setContextClassLoader"));
	}
	this.acc = AccessController.getContext();
	this.ccl = Thread.currentThread().getContextClassLoader();
	}

	public Thread newThread(final Runnable r) {
	return super.newThread(new Runnable() {
	public void run() {
	AccessController.doPrivileged(new PrivilegedAction<Void>() {
	public Void run() {
	Thread.currentThread().setContextClassLoader(ccl);
	r.run();
	return null;
	}
	}, acc);
	}
	});
	}
	}

	/**
	* A wrapper class that exposes only the ExecutorService methods
	* of an ExecutorService implementation.
	*/
	static class DelegatedExecutorService extends AbstractExecutorService {
	private final ExecutorService e;
	DelegatedExecutorService(ExecutorService executor) { e = executor; }
	public void execute(Runnable command) { e.execute(command); }
	public void shutdown() { e.shutdown(); }
	public List<Runnable> 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);
	}
	public Future<?> submit(Runnable task) {
	return e.submit(task);
	}
	public <T> Future<T> submit(Callable<T> task) {
	return e.submit(task);
	}
	public <T> Future<T> submit(Runnable task, T result) {
	return e.submit(task, result);
	}
	public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
	throws InterruptedException {
	return e.invokeAll(tasks);
	}
	public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
	long timeout, TimeUnit unit)
	throws InterruptedException {
	return e.invokeAll(tasks, timeout, unit);
	}
	public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
	throws InterruptedException, ExecutionException {
	return e.invokeAny(tasks);
	}
	public <T> T invokeAny(Collection<? extends Callable<T>> tasks,
	long timeout, TimeUnit unit)
	throws InterruptedException, ExecutionException, TimeoutException {
	return e.invokeAny(tasks, timeout, unit);
	}
	}

	static class FinalizableDelegatedExecutorService
	extends DelegatedExecutorService {
	FinalizableDelegatedExecutorService(ExecutorService executor) {
	super(executor);
	}
	protected void finalize() {
	super.shutdown();
	}
	}

	/**
	* A wrapper class that exposes only the ScheduledExecutorService
	* methods of a ScheduledExecutorService implementation.
	*/
	static class DelegatedScheduledExecutorService
	extends DelegatedExecutorService
	implements ScheduledExecutorService {
	private final ScheduledExecutorService e;
	DelegatedScheduledExecutorService(ScheduledExecutorService executor) {
	super(executor);
	e = executor;
	}
	public ScheduledFuture<?> 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<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) {
	return e.scheduleAtFixedRate(command, initialDelay, period, unit);
	}
	public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) {
	return e.scheduleWithFixedDelay(command, initialDelay, delay, unit);
	}
	}

	/** Cannot instantiate. */
	private Executors() {}
	}

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