util/concurrent/ExecutorService.java

/*
 * 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/licenses/publicdomain
 */

package java.util.concurrent;
import java.util.List;
import java.util.Collection;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;

/**
 * An {@link Executor} that provides methods to manage termination and
 * methods that can produce a {@link Future} for tracking progress of
 * one or more asynchronous tasks.
 *
 * <p> An <tt>ExecutorService</tt> can be shut down, which will cause
 * it to reject new tasks.  Two different methods are provided for
 * shutting down an <tt>ExecutorService</tt>. The {@link #shutdown}
 * method will allow previously submitted tasks to execute before
 * terminating, while the {@link #shutdownNow} method prevents waiting
 * tasks from starting and attempts to stop currently executing tasks.
 * Upon termination, an executor has no tasks actively executing, no
 * tasks awaiting execution, and no new tasks can be submitted.  An
 * unused <tt>ExecutorService</tt> should be shut down to allow
 * reclamation of its resources.
 *
 * <p> Method <tt>submit</tt> extends base method {@link
 * Executor#execute} by creating and returning a {@link Future} that
 * can be used to cancel execution and/or wait for completion.
 * Methods <tt>invokeAny</tt> and <tt>invokeAll</tt> perform the most
 * commonly useful forms of bulk execution, executing a collection of
 * tasks and then waiting for at least one, or all, to
 * complete. (Class {@link ExecutorCompletionService} can be used to
 * write customized variants of these methods.)
 *
 * <p>The {@link Executors} class provides factory methods for the
 * executor services provided in this package.
 *
 * <h3>Usage Examples</h3>
 *
 * Here is a sketch of a network service in which threads in a thread
 * pool service incoming requests. It uses the preconfigured {@link
 * Executors#newFixedThreadPool} factory method:
 *
 * <pre>
 * class NetworkService implements Runnable {
 *   private final ServerSocket serverSocket;
 *   private final ExecutorService pool;
 *
 *   public NetworkService(int port, int poolSize)
 *       throws IOException {
 *     serverSocket = new ServerSocket(port);
 *     pool = Executors.newFixedThreadPool(poolSize);
 *   }
 *
 *   public void run() { // run the service
 *     try {
 *       for (;;) {
 *         pool.execute(new Handler(serverSocket.accept()));
 *       }
 *     } catch (IOException ex) {
 *       pool.shutdown();
 *     }
 *   }
 * }
 *
 * class Handler implements Runnable {
 *   private final Socket socket;
 *   Handler(Socket socket) { this.socket = socket; }
 *   public void run() {
 *     // read and service request on socket
 *   }
 * }
 * </pre>
 *
 * The following method shuts down an <tt>ExecutorService</tt> in two phases,
 * first by calling <tt>shutdown</tt> to reject incoming tasks, and then
 * calling <tt>shutdownNow</tt>, if necessary, to cancel any lingering tasks:
 *
 * <pre>
 * void shutdownAndAwaitTermination(ExecutorService pool) {
 *   pool.shutdown(); // Disable new tasks from being submitted
 *   try {
 *     // Wait a while for existing tasks to terminate
 *     if (!pool.awaitTermination(60, TimeUnit.SECONDS)) {
 *       pool.shutdownNow(); // Cancel currently executing tasks
 *       // Wait a while for tasks to respond to being cancelled
 *       if (!pool.awaitTermination(60, TimeUnit.SECONDS))
 *           System.err.println("Pool did not terminate");
 *     }
 *   } catch (InterruptedException ie) {
 *     pool.shutdownNow(); // (Re-)Cancel if current thread also interrupted
 *     Thread.currentThread().interrupt(); // Preserve interrupt status
 *   }
 * }
 * </pre>
 *
 * <p>Memory consistency effects: Actions in a thread prior to the
 * submission of a {@code Runnable} or {@code Callable} task to an
 * {@code ExecutorService}
 * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
 * any actions taken by that task, which in turn <i>happen-before</i> the
 * result is retrieved via {@code Future.get()}.
 *
 * @since 1.5
 * @author Doug Lea
 */
public interface ExecutorService extends Executor {

    /**
     * Initiates an orderly shutdown in which previously submitted
     * tasks are executed, but no new tasks will be accepted.
     * Invocation has no additional effect if already shut down.
     *
     * @throws SecurityException if a security manager exists and
     *         shutting down this ExecutorService may manipulate
     *         threads that the caller is not permitted to modify
     *         because it does not hold {@link
     *         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
     *         or the security manager's <tt>checkAccess</tt> method
     *         denies access.
     */
    void shutdown();

    /**
     * Attempts to stop all actively executing tasks, halts the
     * processing of waiting tasks, and returns a list of the tasks that were
     * awaiting execution.
     *
     * <p>There are no guarantees beyond best-effort attempts to stop
     * processing actively executing tasks.  For example, typical
     * implementations will cancel via {@link Thread#interrupt}, so any
     * task that fails to respond to interrupts may never terminate.
     *
     * @return list of tasks that never commenced execution
     * @throws SecurityException if a security manager exists and
     *         shutting down this ExecutorService may manipulate
     *         threads that the caller is not permitted to modify
     *         because it does not hold {@link
     *         java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
     *         or the security manager's <tt>checkAccess</tt> method
     *         denies access.
     */
    List<Runnable> shutdownNow();

    /**
     * Returns <tt>true</tt> if this executor has been shut down.
     *
     * @return <tt>true</tt> if this executor has been shut down
     */
    boolean isShutdown();

    /**
     * Returns <tt>true</tt> if all tasks have completed following shut down.
     * Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
     * either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
     *
     * @return <tt>true</tt> if all tasks have completed following shut down
     */
    boolean isTerminated();

    /**
     * Blocks until all tasks have completed execution after a shutdown
     * request, or the timeout occurs, or the current thread is
     * interrupted, whichever happens first.
     *
     * @param timeout the maximum time to wait
     * @param unit the time unit of the timeout argument
     * @return <tt>true</tt> if this executor terminated and
     *         <tt>false</tt> if the timeout elapsed before termination
     * @throws InterruptedException if interrupted while waiting
     */
    boolean awaitTermination(long timeout, TimeUnit unit)
        throws InterruptedException;


    /**
     * Submits a value-returning task for execution and returns a
     * Future representing the pending results of the task. The
     * Future's <tt>get</tt> method will return the task's result upon
     * successful completion.
     *
     * <p>
     * If you would like to immediately block waiting
     * for a task, you can use constructions of the form
     * <tt>result = exec.submit(aCallable).get();</tt>
     *
     * <p> Note: The {@link Executors} class includes a set of methods
     * that can convert some other common closure-like objects,
     * for example, {@link java.security.PrivilegedAction} to
     * {@link Callable} form so they can be submitted.
     *
     * @param task the task to submit
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if the task cannot be
     *         scheduled for execution
     * @throws NullPointerException if the task is null
     */
    <T> Future<T> submit(Callable<T> task);

    /**
     * Submits a Runnable task for execution and returns a Future
     * representing that task. The Future's <tt>get</tt> method will
     * return the given result upon successful completion.
     *
     * @param task the task to submit
     * @param result the result to return
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if the task cannot be
     *         scheduled for execution
     * @throws NullPointerException if the task is null
     */
    <T> Future<T> submit(Runnable task, T result);

    /**
     * Submits a Runnable task for execution and returns a Future
     * representing that task. The Future's <tt>get</tt> method will
     * return <tt>null</tt> upon <em>successful</em> completion.
     *
     * @param task the task to submit
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if the task cannot be
     *         scheduled for execution
     * @throws NullPointerException if the task is null
     */
    Future<?> submit(Runnable task);

    /**
     * Executes the given tasks, returning a list of Futures holding
     * their status and results when all complete.
     * {@link Future#isDone} is <tt>true</tt> for each
     * element of the returned list.
     * Note that a <em>completed</em> task could have
     * terminated either normally or by throwing an exception.
     * The results of this method are undefined if the given
     * collection is modified while this operation is in progress.
     *
     * @param tasks the collection of tasks
     * @return A list of Futures representing the tasks, in the same
     *         sequential order as produced by the iterator for the
     *         given task list, each of which has completed.
     * @throws InterruptedException if interrupted while waiting, in
     *         which case unfinished tasks are cancelled.
     * @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
     * @throws RejectedExecutionException if any task cannot be
     *         scheduled for execution
     */

    <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
        throws InterruptedException;

    /**
     * Executes the given tasks, returning a list of Futures holding
     * their status and results
     * when all complete or the timeout expires, whichever happens first.
     * {@link Future#isDone} is <tt>true</tt> for each
     * element of the returned list.
     * Upon return, tasks that have not completed are cancelled.
     * Note that a <em>completed</em> task could have
     * terminated either normally or by throwing an exception.
     * The results of this method are undefined if the given
     * collection is modified while this operation is in progress.
     *
     * @param tasks the collection of tasks
     * @param timeout the maximum time to wait
     * @param unit the time unit of the timeout argument
     * @return a list of Futures representing the tasks, in the same
     *         sequential order as produced by the iterator for the
     *         given task list. If the operation did not time out,
     *         each task will have completed. If it did time out, some
     *         of these tasks will not have completed.
     * @throws InterruptedException if interrupted while waiting, in
     *         which case unfinished tasks are cancelled
     * @throws NullPointerException if tasks, any of its elements, or
     *         unit are <tt>null</tt>
     * @throws RejectedExecutionException if any task cannot be scheduled
     *         for execution
     */
    <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
                                  long timeout, TimeUnit unit)
        throws InterruptedException;

    /**
     * Executes the given tasks, returning the result
     * of one that has completed successfully (i.e., without throwing
     * an exception), if any do. Upon normal or exceptional return,
     * tasks that have not completed are cancelled.
     * The results of this method are undefined if the given
     * collection is modified while this operation is in progress.
     *
     * @param tasks the collection of tasks
     * @return the result returned by one of the tasks
     * @throws InterruptedException if interrupted while waiting
     * @throws NullPointerException if tasks or any of its elements
     *         are <tt>null</tt>
     * @throws IllegalArgumentException if tasks is empty
     * @throws ExecutionException if no task successfully completes
     * @throws RejectedExecutionException if tasks cannot be scheduled
     *         for execution
     */
    <T> T invokeAny(Collection<? extends Callable<T>> tasks)
        throws InterruptedException, ExecutionException;

    /**
     * Executes the given tasks, returning the result
     * of one that has completed successfully (i.e., without throwing
     * an exception), if any do before the given timeout elapses.
     * Upon normal or exceptional return, tasks that have not
     * completed are cancelled.
     * The results of this method are undefined if the given
     * collection is modified while this operation is in progress.
     *
     * @param tasks the collection of tasks
     * @param timeout the maximum time to wait
     * @param unit the time unit of the timeout argument
     * @return the result returned by one of the tasks.
     * @throws InterruptedException if interrupted while waiting
     * @throws NullPointerException if tasks, any of its elements, or
     *         unit are <tt>null</tt>
     * @throws TimeoutException if the given timeout elapses before
     *         any task successfully completes
     * @throws ExecutionException if no task successfully completes
     * @throws RejectedExecutionException if tasks cannot be scheduled
     *         for execution
     */
    <T> T invokeAny(Collection<? extends Callable<T>> tasks,
                    long timeout, TimeUnit unit)
        throws InterruptedException, ExecutionException, TimeoutException;
}
Revision:	1.47
Committed:	Fri Jul 14 11:01:44 2006 UTC (17 years, 10 months ago) by dl
Branch:	MAIN
Changes since 1.46:	+36 -11 lines
Log Message:	Improve documentation about shutdown
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3	dl	1.22	* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/licenses/publicdomain
5	dl	1.1	*/
6
7			package java.util.concurrent;
8			import java.util.List;
9	dl	1.15	import java.util.Collection;
10	tim	1.8	import java.security.PrivilegedAction;
11			import java.security.PrivilegedExceptionAction;
12	dl	1.1
13			/**
14	dl	1.25	* An {@link Executor} that provides methods to manage termination and
15	dl	1.20	* methods that can produce a {@link Future} for tracking progress of
16	jsr166	1.33	* one or more asynchronous tasks.
17	dl	1.17	*
18	dl	1.47	* <p> An <tt>ExecutorService</tt> can be shut down, which will cause
19			* it to reject new tasks. Two different methods are provided for
20			* shutting down an <tt>ExecutorService</tt>. The {@link #shutdown}
21			* method will allow previously submitted tasks to execute before
22			* terminating, while the {@link #shutdownNow} method prevents waiting
23			* tasks from starting and attempts to stop currently executing tasks.
24			* Upon termination, an executor has no tasks actively executing, no
25			* tasks awaiting execution, and no new tasks can be submitted. An
26			* unused <tt>ExecutorService</tt> should be shut down to allow
27			* reclamation of its resources.
28	dl	1.1	*
29	dl	1.20	* <p> Method <tt>submit</tt> extends base method {@link
30			* Executor#execute} by creating and returning a {@link Future} that
31			* can be used to cancel execution and/or wait for completion.
32			* Methods <tt>invokeAny</tt> and <tt>invokeAll</tt> perform the most
33			* commonly useful forms of bulk execution, executing a collection of
34			* tasks and then waiting for at least one, or all, to
35			* complete. (Class {@link ExecutorCompletionService} can be used to
36			* write customized variants of these methods.)
37	dl	1.17	*
38	dl	1.7	* <p>The {@link Executors} class provides factory methods for the
39			* executor services provided in this package.
40	dl	1.1	*
41	dl	1.47	* <h3>Usage Examples</h3>
42	dl	1.23	*
43			* Here is a sketch of a network service in which threads in a thread
44			* pool service incoming requests. It uses the preconfigured {@link
45			* Executors#newFixedThreadPool} factory method:
46			*
47			* <pre>
48	dl	1.47	* class NetworkService implements Runnable {
49	jsr166	1.37	* private final ServerSocket serverSocket;
50			* private final ExecutorService pool;
51	dl	1.23	*
52	jsr166	1.37	* public NetworkService(int port, int poolSize)
53			* throws IOException {
54			* serverSocket = new ServerSocket(port);
55			* pool = Executors.newFixedThreadPool(poolSize);
56			* }
57	jsr166	1.33	*
58	dl	1.47	* public void run() { // run the service
59	jsr166	1.37	* try {
60			* for (;;) {
61			* pool.execute(new Handler(serverSocket.accept()));
62			* }
63			* } catch (IOException ex) {
64			* pool.shutdown();
65			* }
66			* }
67			* }
68	dl	1.23	*
69	jsr166	1.37	* class Handler implements Runnable {
70			* private final Socket socket;
71			* Handler(Socket socket) { this.socket = socket; }
72			* public void run() {
73	dl	1.47	* // read and service request on socket
74			* }
75			* }
76			* </pre>
77			*
78			* The following method shuts down an <tt>ExecutorService</tt> in two phases,
79			* first by calling <tt>shutdown</tt> to reject incoming tasks, and then
80			* calling <tt>shutdownNow</tt>, if necessary, to cancel any lingering tasks:
81			*
82			* <pre>
83			* void shutdownAndAwaitTermination(ExecutorService pool) {
84			* pool.shutdown(); // Disable new tasks from being submitted
85			* try {
86			* // Wait a while for existing tasks to terminate
87			* if (!pool.awaitTermination(60, TimeUnit.SECONDS)) {
88			* pool.shutdownNow(); // Cancel currently executing tasks
89			* // Wait a while for tasks to respond to being cancelled
90			* if (!pool.awaitTermination(60, TimeUnit.SECONDS))
91			* System.err.println("Pool did not terminate");
92			* }
93			* } catch (InterruptedException ie) {
94			* pool.shutdownNow(); // (Re-)Cancel if current thread also interrupted
95			* Thread.currentThread().interrupt(); // Preserve interrupt status
96	jsr166	1.37	* }
97	dl	1.23	* }
98			* </pre>
99	brian	1.40	*
100	jsr166	1.43	* <p>Memory consistency effects: Actions in a thread prior to the
101			* submission of a {@code Runnable} or {@code Callable} task to an
102			* {@code ExecutorService}
103			* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
104			* any actions taken by that task, which in turn <i>happen-before</i> the
105			* result is retrieved via {@code Future.get()}.
106	brian	1.40	*
107	dl	1.1	* @since 1.5
108	dl	1.5	* @author Doug Lea
109	dl	1.1	*/
110			public interface ExecutorService extends Executor {
111	tim	1.8
112	dl	1.17	/**
113			* Initiates an orderly shutdown in which previously submitted
114	jsr166	1.37	* tasks are executed, but no new tasks will be accepted.
115			* Invocation has no additional effect if already shut down.
116			*
117	dl	1.17	* @throws SecurityException if a security manager exists and
118	jsr166	1.37	* shutting down this ExecutorService may manipulate
119			* threads that the caller is not permitted to modify
120			* because it does not hold {@link
121			* java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
122			* or the security manager's <tt>checkAccess</tt> method
123			* denies access.
124	dl	1.17	*/
125			void shutdown();
126
127			/**
128			* Attempts to stop all actively executing tasks, halts the
129			* processing of waiting tasks, and returns a list of the tasks that were
130	jsr166	1.33	* awaiting execution.
131			*
132	dl	1.17	* <p>There are no guarantees beyond best-effort attempts to stop
133			* processing actively executing tasks. For example, typical
134	jsr166	1.39	* implementations will cancel via {@link Thread#interrupt}, so any
135			* task that fails to respond to interrupts may never terminate.
136	dl	1.17	*
137			* @return list of tasks that never commenced execution
138			* @throws SecurityException if a security manager exists and
139	jsr166	1.37	* shutting down this ExecutorService may manipulate
140			* threads that the caller is not permitted to modify
141			* because it does not hold {@link
142			* java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
143			* or the security manager's <tt>checkAccess</tt> method
144			* denies access.
145	dl	1.17	*/
146			List<Runnable> shutdownNow();
147
148			/**
149			* Returns <tt>true</tt> if this executor has been shut down.
150			*
151			* @return <tt>true</tt> if this executor has been shut down
152			*/
153			boolean isShutdown();
154
155			/**
156			* Returns <tt>true</tt> if all tasks have completed following shut down.
157			* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
158			* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
159			*
160			* @return <tt>true</tt> if all tasks have completed following shut down
161			*/
162			boolean isTerminated();
163
164			/**
165			* Blocks until all tasks have completed execution after a shutdown
166			* request, or the timeout occurs, or the current thread is
167	jsr166	1.36	* interrupted, whichever happens first.
168	dl	1.17	*
169			* @param timeout the maximum time to wait
170			* @param unit the time unit of the timeout argument
171	jsr166	1.37	* @return <tt>true</tt> if this executor terminated and
172			* <tt>false</tt> if the timeout elapsed before termination
173	dl	1.17	* @throws InterruptedException if interrupted while waiting
174			*/
175			boolean awaitTermination(long timeout, TimeUnit unit)
176			throws InterruptedException;
177
178
179	tim	1.8	/**
180	dl	1.30	* Submits a value-returning task for execution and returns a
181	dl	1.31	* Future representing the pending results of the task. The
182	dl	1.32	* Future's <tt>get</tt> method will return the task's result upon
183	jsr166	1.37	* successful completion.
184	tim	1.8	*
185	dl	1.19	* <p>
186	dl	1.20	* If you would like to immediately block waiting
187	dl	1.19	* for a task, you can use constructions of the form
188			* <tt>result = exec.submit(aCallable).get();</tt>
189	dl	1.20	*
190			* <p> Note: The {@link Executors} class includes a set of methods
191			* that can convert some other common closure-like objects,
192			* for example, {@link java.security.PrivilegedAction} to
193			* {@link Callable} form so they can be submitted.
194			*
195	tim	1.8	* @param task the task to submit
196			* @return a Future representing pending completion of the task
197	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
198			* scheduled for execution
199			* @throws NullPointerException if the task is null
200	tim	1.8	*/
201			<T> Future<T> submit(Callable<T> task);
202
203			/**
204	dl	1.30	* Submits a Runnable task for execution and returns a Future
205	jsr166	1.33	* representing that task. The Future's <tt>get</tt> method will
206	dl	1.31	* return the given result upon successful completion.
207	dl	1.20	*
208			* @param task the task to submit
209			* @param result the result to return
210	dl	1.31	* @return a Future representing pending completion of the task
211	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
212			* scheduled for execution
213			* @throws NullPointerException if the task is null
214	dl	1.20	*/
215			<T> Future<T> submit(Runnable task, T result);
216
217			/**
218	jsr166	1.33	* Submits a Runnable task for execution and returns a Future
219			* representing that task. The Future's <tt>get</tt> method will
220	jsr166	1.37	* return <tt>null</tt> upon <em>successful</em> completion.
221	dl	1.1	*
222	dl	1.17	* @param task the task to submit
223	dl	1.31	* @return a Future representing pending completion of the task
224	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
225			* scheduled for execution
226			* @throws NullPointerException if the task is null
227	dl	1.1	*/
228	dl	1.18	Future<?> submit(Runnable task);
229	dl	1.15
230	dl	1.11	/**
231	dl	1.27	* Executes the given tasks, returning a list of Futures holding
232	jsr166	1.33	* their status and results when all complete.
233			* {@link Future#isDone} is <tt>true</tt> for each
234	dl	1.27	* element of the returned list.
235	dl	1.12	* Note that a <em>completed</em> task could have
236			* terminated either normally or by throwing an exception.
237	dl	1.21	* The results of this method are undefined if the given
238			* collection is modified while this operation is in progress.
239	jsr166	1.37	*
240	dl	1.11	* @param tasks the collection of tasks
241	dl	1.13	* @return A list of Futures representing the tasks, in the same
242	jsr166	1.37	* sequential order as produced by the iterator for the
243			* given task list, each of which has completed.
244	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
245	jsr166	1.37	* which case unfinished tasks are cancelled.
246	dl	1.13	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
247	jsr166	1.37	* @throws RejectedExecutionException if any task cannot be
248			* scheduled for execution
249	dl	1.11	*/
250	jsr166	1.38
251			<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
252	dl	1.11	throws InterruptedException;
253
254			/**
255	dl	1.27	* Executes the given tasks, returning a list of Futures holding
256	jsr166	1.33	* their status and results
257	dl	1.15	* when all complete or the timeout expires, whichever happens first.
258	jsr166	1.33	* {@link Future#isDone} is <tt>true</tt> for each
259	dl	1.27	* element of the returned list.
260	dl	1.11	* Upon return, tasks that have not completed are cancelled.
261	dl	1.12	* Note that a <em>completed</em> task could have
262			* terminated either normally or by throwing an exception.
263	dl	1.21	* The results of this method are undefined if the given
264			* collection is modified while this operation is in progress.
265	jsr166	1.37	*
266	dl	1.11	* @param tasks the collection of tasks
267			* @param timeout the maximum time to wait
268	dl	1.15	* @param unit the time unit of the timeout argument
269	jsr166	1.37	* @return a list of Futures representing the tasks, in the same
270			* sequential order as produced by the iterator for the
271			* given task list. If the operation did not time out,
272			* each task will have completed. If it did time out, some
273			* of these tasks will not have completed.
274	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
275	jsr166	1.37	* which case unfinished tasks are cancelled
276	dl	1.17	* @throws NullPointerException if tasks, any of its elements, or
277	jsr166	1.37	* unit are <tt>null</tt>
278	dl	1.13	* @throws RejectedExecutionException if any task cannot be scheduled
279	jsr166	1.37	* for execution
280	dl	1.11	*/
281	jsr166	1.38	<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
282	jsr166	1.33	long timeout, TimeUnit unit)
283	dl	1.11	throws InterruptedException;
284
285			/**
286	dl	1.17	* Executes the given tasks, returning the result
287	dl	1.15	* of one that has completed successfully (i.e., without throwing
288			* an exception), if any do. Upon normal or exceptional return,
289			* tasks that have not completed are cancelled.
290	dl	1.21	* The results of this method are undefined if the given
291			* collection is modified while this operation is in progress.
292	jsr166	1.37	*
293	dl	1.11	* @param tasks the collection of tasks
294	jsr166	1.37	* @return the result returned by one of the tasks
295	dl	1.15	* @throws InterruptedException if interrupted while waiting
296			* @throws NullPointerException if tasks or any of its elements
297	jsr166	1.37	* are <tt>null</tt>
298			* @throws IllegalArgumentException if tasks is empty
299	dl	1.15	* @throws ExecutionException if no task successfully completes
300			* @throws RejectedExecutionException if tasks cannot be scheduled
301	jsr166	1.37	* for execution
302	dl	1.11	*/
303	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks)
304	dl	1.15	throws InterruptedException, ExecutionException;
305	dl	1.11
306			/**
307	dl	1.17	* Executes the given tasks, returning the result
308	dl	1.15	* of one that has completed successfully (i.e., without throwing
309			* an exception), if any do before the given timeout elapses.
310			* Upon normal or exceptional return, tasks that have not
311			* completed are cancelled.
312	dl	1.21	* The results of this method are undefined if the given
313			* collection is modified while this operation is in progress.
314	jsr166	1.37	*
315	dl	1.11	* @param tasks the collection of tasks
316			* @param timeout the maximum time to wait
317			* @param unit the time unit of the timeout argument
318	jsr166	1.37	* @return the result returned by one of the tasks.
319	dl	1.15	* @throws InterruptedException if interrupted while waiting
320	dl	1.17	* @throws NullPointerException if tasks, any of its elements, or
321	jsr166	1.37	* unit are <tt>null</tt>
322	dl	1.15	* @throws TimeoutException if the given timeout elapses before
323	jsr166	1.37	* any task successfully completes
324	dl	1.15	* @throws ExecutionException if no task successfully completes
325			* @throws RejectedExecutionException if tasks cannot be scheduled
326	jsr166	1.37	* for execution
327	dl	1.11	*/
328	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks,
329	jsr166	1.33	long timeout, TimeUnit unit)
330	dl	1.15	throws InterruptedException, ExecutionException, TimeoutException;
331	dl	1.1	}