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 stop accepting new tasks.  After being shut down, the executor
 * will eventually terminate, at which point no tasks are actively
 * executing, no tasks are 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 Example</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 {
 *   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 serve() {
 *     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
 *   }
 * }
 * </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:	1.45
Committed:	Tue Mar 21 00:22:43 2006 UTC (18 years, 2 months ago) by dl
Branch:	MAIN
Changes since 1.44:	+2 -1 lines
Log Message:	Document and better support finalization
#	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	1.25	* <p>
19	dl	1.7	* An <tt>ExecutorService</tt> can be shut down, which will cause it
20			* to stop accepting new tasks. After being shut down, the executor
21			* will eventually terminate, at which point no tasks are actively
22	dl	1.1	* executing, no tasks are awaiting execution, and no new tasks can be
23	dl	1.45	* submitted. An unused <tt>ExecutorService</tt> should be shut down
24			* to allow reclamation of its resources.
25	dl	1.1	*
26	dl	1.20	* <p> Method <tt>submit</tt> extends base method {@link
27			* Executor#execute} by creating and returning a {@link Future} that
28			* can be used to cancel execution and/or wait for completion.
29			* Methods <tt>invokeAny</tt> and <tt>invokeAll</tt> perform the most
30			* commonly useful forms of bulk execution, executing a collection of
31			* tasks and then waiting for at least one, or all, to
32			* complete. (Class {@link ExecutorCompletionService} can be used to
33			* write customized variants of these methods.)
34	dl	1.17	*
35	dl	1.7	* <p>The {@link Executors} class provides factory methods for the
36			* executor services provided in this package.
37	dl	1.1	*
38	dl	1.23	* <h3>Usage Example</h3>
39			*
40			* Here is a sketch of a network service in which threads in a thread
41			* pool service incoming requests. It uses the preconfigured {@link
42			* Executors#newFixedThreadPool} factory method:
43			*
44			* <pre>
45			* class NetworkService {
46	jsr166	1.37	* private final ServerSocket serverSocket;
47			* private final ExecutorService pool;
48	dl	1.23	*
49	jsr166	1.37	* public NetworkService(int port, int poolSize)
50			* throws IOException {
51			* serverSocket = new ServerSocket(port);
52			* pool = Executors.newFixedThreadPool(poolSize);
53			* }
54	jsr166	1.33	*
55	jsr166	1.37	* public void serve() {
56			* try {
57			* for (;;) {
58			* pool.execute(new Handler(serverSocket.accept()));
59			* }
60			* } catch (IOException ex) {
61			* pool.shutdown();
62			* }
63			* }
64			* }
65	dl	1.23	*
66	jsr166	1.37	* class Handler implements Runnable {
67			* private final Socket socket;
68			* Handler(Socket socket) { this.socket = socket; }
69			* public void run() {
70			* // read and service request
71			* }
72	dl	1.23	* }
73			* </pre>
74	brian	1.40	*
75	jsr166	1.43	* <p>Memory consistency effects: Actions in a thread prior to the
76			* submission of a {@code Runnable} or {@code Callable} task to an
77			* {@code ExecutorService}
78			* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
79			* any actions taken by that task, which in turn <i>happen-before</i> the
80			* result is retrieved via {@code Future.get()}.
81	brian	1.40	*
82	dl	1.1	* @since 1.5
83	dl	1.5	* @author Doug Lea
84	dl	1.1	*/
85			public interface ExecutorService extends Executor {
86	tim	1.8
87	dl	1.17	/**
88			* Initiates an orderly shutdown in which previously submitted
89	jsr166	1.37	* tasks are executed, but no new tasks will be accepted.
90			* Invocation has no additional effect if already shut down.
91			*
92	dl	1.17	* @throws SecurityException if a security manager exists and
93	jsr166	1.37	* shutting down this ExecutorService may manipulate
94			* threads that the caller is not permitted to modify
95			* because it does not hold {@link
96			* java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
97			* or the security manager's <tt>checkAccess</tt> method
98			* denies access.
99	dl	1.17	*/
100			void shutdown();
101
102			/**
103			* Attempts to stop all actively executing tasks, halts the
104			* processing of waiting tasks, and returns a list of the tasks that were
105	jsr166	1.33	* awaiting execution.
106			*
107	dl	1.17	* <p>There are no guarantees beyond best-effort attempts to stop
108			* processing actively executing tasks. For example, typical
109	jsr166	1.39	* implementations will cancel via {@link Thread#interrupt}, so any
110			* task that fails to respond to interrupts may never terminate.
111	dl	1.17	*
112			* @return list of tasks that never commenced execution
113			* @throws SecurityException if a security manager exists and
114	jsr166	1.37	* shutting down this ExecutorService may manipulate
115			* threads that the caller is not permitted to modify
116			* because it does not hold {@link
117			* java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
118			* or the security manager's <tt>checkAccess</tt> method
119			* denies access.
120	dl	1.17	*/
121			List<Runnable> shutdownNow();
122
123			/**
124			* Returns <tt>true</tt> if this executor has been shut down.
125			*
126			* @return <tt>true</tt> if this executor has been shut down
127			*/
128			boolean isShutdown();
129
130			/**
131			* Returns <tt>true</tt> if all tasks have completed following shut down.
132			* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
133			* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
134			*
135			* @return <tt>true</tt> if all tasks have completed following shut down
136			*/
137			boolean isTerminated();
138
139			/**
140			* Blocks until all tasks have completed execution after a shutdown
141			* request, or the timeout occurs, or the current thread is
142	jsr166	1.36	* interrupted, whichever happens first.
143	dl	1.17	*
144			* @param timeout the maximum time to wait
145			* @param unit the time unit of the timeout argument
146	jsr166	1.37	* @return <tt>true</tt> if this executor terminated and
147			* <tt>false</tt> if the timeout elapsed before termination
148	dl	1.17	* @throws InterruptedException if interrupted while waiting
149			*/
150			boolean awaitTermination(long timeout, TimeUnit unit)
151			throws InterruptedException;
152
153
154	tim	1.8	/**
155	dl	1.30	* Submits a value-returning task for execution and returns a
156	dl	1.31	* Future representing the pending results of the task. The
157	dl	1.32	* Future's <tt>get</tt> method will return the task's result upon
158	jsr166	1.37	* successful completion.
159	tim	1.8	*
160	dl	1.19	* <p>
161	dl	1.20	* If you would like to immediately block waiting
162	dl	1.19	* for a task, you can use constructions of the form
163			* <tt>result = exec.submit(aCallable).get();</tt>
164	dl	1.20	*
165			* <p> Note: The {@link Executors} class includes a set of methods
166			* that can convert some other common closure-like objects,
167			* for example, {@link java.security.PrivilegedAction} to
168			* {@link Callable} form so they can be submitted.
169			*
170	tim	1.8	* @param task the task to submit
171			* @return a Future representing pending completion of the task
172	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
173			* scheduled for execution
174			* @throws NullPointerException if the task is null
175	tim	1.8	*/
176			<T> Future<T> submit(Callable<T> task);
177
178			/**
179	dl	1.30	* Submits a Runnable task for execution and returns a Future
180	jsr166	1.33	* representing that task. The Future's <tt>get</tt> method will
181	dl	1.31	* return the given result upon successful completion.
182	dl	1.20	*
183			* @param task the task to submit
184			* @param result the result to return
185	dl	1.31	* @return a Future representing pending completion of the task
186	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
187			* scheduled for execution
188			* @throws NullPointerException if the task is null
189	dl	1.20	*/
190			<T> Future<T> submit(Runnable task, T result);
191
192			/**
193	jsr166	1.33	* Submits a Runnable task for execution and returns a Future
194			* representing that task. The Future's <tt>get</tt> method will
195	jsr166	1.37	* return <tt>null</tt> upon <em>successful</em> completion.
196	dl	1.1	*
197	dl	1.17	* @param task the task to submit
198	dl	1.31	* @return a Future representing pending completion of the task
199	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
200			* scheduled for execution
201			* @throws NullPointerException if the task is null
202	dl	1.1	*/
203	dl	1.18	Future<?> submit(Runnable task);
204	dl	1.15
205	dl	1.11	/**
206	dl	1.27	* Executes the given tasks, returning a list of Futures holding
207	jsr166	1.33	* their status and results when all complete.
208			* {@link Future#isDone} is <tt>true</tt> for each
209	dl	1.27	* element of the returned list.
210	dl	1.12	* Note that a <em>completed</em> task could have
211			* terminated either normally or by throwing an exception.
212	dl	1.21	* The results of this method are undefined if the given
213			* collection is modified while this operation is in progress.
214	jsr166	1.37	*
215	dl	1.11	* @param tasks the collection of tasks
216	dl	1.13	* @return A list of Futures representing the tasks, in the same
217	jsr166	1.37	* sequential order as produced by the iterator for the
218			* given task list, each of which has completed.
219	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
220	jsr166	1.37	* which case unfinished tasks are cancelled.
221	dl	1.13	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
222	jsr166	1.37	* @throws RejectedExecutionException if any task cannot be
223			* scheduled for execution
224	dl	1.11	*/
225	jsr166	1.38
226			<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
227	dl	1.11	throws InterruptedException;
228
229			/**
230	dl	1.27	* Executes the given tasks, returning a list of Futures holding
231	jsr166	1.33	* their status and results
232	dl	1.15	* when all complete or the timeout expires, whichever happens first.
233	jsr166	1.33	* {@link Future#isDone} is <tt>true</tt> for each
234	dl	1.27	* element of the returned list.
235	dl	1.11	* Upon return, tasks that have not completed are cancelled.
236	dl	1.12	* Note that a <em>completed</em> task could have
237			* terminated either normally or by throwing an exception.
238	dl	1.21	* The results of this method are undefined if the given
239			* collection is modified while this operation is in progress.
240	jsr166	1.37	*
241	dl	1.11	* @param tasks the collection of tasks
242			* @param timeout the maximum time to wait
243	dl	1.15	* @param unit the time unit of the timeout argument
244	jsr166	1.37	* @return a list of Futures representing the tasks, in the same
245			* sequential order as produced by the iterator for the
246			* given task list. If the operation did not time out,
247			* each task will have completed. If it did time out, some
248			* of these tasks will not have completed.
249	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
250	jsr166	1.37	* which case unfinished tasks are cancelled
251	dl	1.17	* @throws NullPointerException if tasks, any of its elements, or
252	jsr166	1.37	* unit are <tt>null</tt>
253	dl	1.13	* @throws RejectedExecutionException if any task cannot be scheduled
254	jsr166	1.37	* for execution
255	dl	1.11	*/
256	jsr166	1.38	<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
257	jsr166	1.33	long timeout, TimeUnit unit)
258	dl	1.11	throws InterruptedException;
259
260			/**
261	dl	1.17	* Executes the given tasks, returning the result
262	dl	1.15	* of one that has completed successfully (i.e., without throwing
263			* an exception), if any do. Upon normal or exceptional return,
264			* tasks that have not completed are cancelled.
265	dl	1.21	* The results of this method are undefined if the given
266			* collection is modified while this operation is in progress.
267	jsr166	1.37	*
268	dl	1.11	* @param tasks the collection of tasks
269	jsr166	1.37	* @return the result returned by one of the tasks
270	dl	1.15	* @throws InterruptedException if interrupted while waiting
271			* @throws NullPointerException if tasks or any of its elements
272	jsr166	1.37	* are <tt>null</tt>
273			* @throws IllegalArgumentException if tasks is empty
274	dl	1.15	* @throws ExecutionException if no task successfully completes
275			* @throws RejectedExecutionException if tasks cannot be scheduled
276	jsr166	1.37	* for execution
277	dl	1.11	*/
278	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks)
279	dl	1.15	throws InterruptedException, ExecutionException;
280	dl	1.11
281			/**
282	dl	1.17	* Executes the given tasks, returning the result
283	dl	1.15	* of one that has completed successfully (i.e., without throwing
284			* an exception), if any do before the given timeout elapses.
285			* Upon normal or exceptional return, tasks that have not
286			* completed are cancelled.
287	dl	1.21	* The results of this method are undefined if the given
288			* collection is modified while this operation is in progress.
289	jsr166	1.37	*
290	dl	1.11	* @param tasks the collection of tasks
291			* @param timeout the maximum time to wait
292			* @param unit the time unit of the timeout argument
293	jsr166	1.37	* @return the result returned by one of the tasks.
294	dl	1.15	* @throws InterruptedException if interrupted while waiting
295	dl	1.17	* @throws NullPointerException if tasks, any of its elements, or
296	jsr166	1.37	* unit are <tt>null</tt>
297	dl	1.15	* @throws TimeoutException if the given timeout elapses before
298	jsr166	1.37	* any task successfully completes
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	jsr166	1.33	long timeout, TimeUnit unit)
305	dl	1.15	throws InterruptedException, ExecutionException, TimeoutException;
306	dl	1.1	}