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/publicdomain/zero/1.0/
 */

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) {
 *     // (Re-)Cancel if current thread also interrupted
 *     pool.shutdownNow();
 *     // Preserve interrupt status
 *     Thread.currentThread().interrupt();
 *   }
 * }
 * </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.
     *
     * <p>This method does not wait for previously submitted tasks to
     * complete execution.  Use {@link #awaitTermination awaitTermination}
     * to do that.
     *
     * @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>This method does not wait for actively executing tasks to
     * terminate.  Use {@link #awaitTermination awaitTermination} to
     * do that.
     *
     * <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 element task
     *         subject to execution is <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, or unit, or any element
     *         task subject to execution is <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:	1.51
Committed:	Tue Mar 15 19:47:03 2011 UTC (13 years, 2 months ago) by jsr166
Branch:	MAIN
CVS Tags:	release-1_7_0
Changes since 1.50:	+1 -1 lines
Log Message:	Update Creative Commons license URL in legal notices
#	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	jsr166	1.51	* http://creativecommons.org/publicdomain/zero/1.0/
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	jsr166	1.48	* // (Re-)Cancel if current thread also interrupted
95			* pool.shutdownNow();
96			* // Preserve interrupt status
97			* Thread.currentThread().interrupt();
98	jsr166	1.37	* }
99	dl	1.23	* }
100			* </pre>
101	brian	1.40	*
102	jsr166	1.43	* <p>Memory consistency effects: Actions in a thread prior to the
103			* submission of a {@code Runnable} or {@code Callable} task to an
104			* {@code ExecutorService}
105			* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
106			* any actions taken by that task, which in turn <i>happen-before</i> the
107			* result is retrieved via {@code Future.get()}.
108	brian	1.40	*
109	dl	1.1	* @since 1.5
110	dl	1.5	* @author Doug Lea
111	dl	1.1	*/
112			public interface ExecutorService extends Executor {
113	tim	1.8
114	dl	1.17	/**
115			* Initiates an orderly shutdown in which previously submitted
116	jsr166	1.37	* tasks are executed, but no new tasks will be accepted.
117			* Invocation has no additional effect if already shut down.
118			*
119	jsr166	1.49	* <p>This method does not wait for previously submitted tasks to
120			* complete execution. Use {@link #awaitTermination awaitTermination}
121			* to do that.
122			*
123	dl	1.17	* @throws SecurityException if a security manager exists and
124	jsr166	1.37	* shutting down this ExecutorService may manipulate
125			* threads that the caller is not permitted to modify
126			* because it does not hold {@link
127			* java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
128			* or the security manager's <tt>checkAccess</tt> method
129			* denies access.
130	dl	1.17	*/
131			void shutdown();
132
133			/**
134			* Attempts to stop all actively executing tasks, halts the
135	jsr166	1.49	* processing of waiting tasks, and returns a list of the tasks
136			* that were awaiting execution.
137			*
138			* <p>This method does not wait for actively executing tasks to
139			* terminate. Use {@link #awaitTermination awaitTermination} to
140			* do that.
141	jsr166	1.33	*
142	dl	1.17	* <p>There are no guarantees beyond best-effort attempts to stop
143			* processing actively executing tasks. For example, typical
144	jsr166	1.39	* implementations will cancel via {@link Thread#interrupt}, so any
145			* task that fails to respond to interrupts may never terminate.
146	dl	1.17	*
147			* @return list of tasks that never commenced execution
148			* @throws SecurityException if a security manager exists and
149	jsr166	1.37	* shutting down this ExecutorService may manipulate
150			* threads that the caller is not permitted to modify
151			* because it does not hold {@link
152			* java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
153			* or the security manager's <tt>checkAccess</tt> method
154			* denies access.
155	dl	1.17	*/
156			List<Runnable> shutdownNow();
157
158			/**
159			* Returns <tt>true</tt> if this executor has been shut down.
160			*
161			* @return <tt>true</tt> if this executor has been shut down
162			*/
163			boolean isShutdown();
164
165			/**
166			* Returns <tt>true</tt> if all tasks have completed following shut down.
167			* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
168			* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
169			*
170			* @return <tt>true</tt> if all tasks have completed following shut down
171			*/
172			boolean isTerminated();
173
174			/**
175			* Blocks until all tasks have completed execution after a shutdown
176			* request, or the timeout occurs, or the current thread is
177	jsr166	1.36	* interrupted, whichever happens first.
178	dl	1.17	*
179			* @param timeout the maximum time to wait
180			* @param unit the time unit of the timeout argument
181	jsr166	1.37	* @return <tt>true</tt> if this executor terminated and
182			* <tt>false</tt> if the timeout elapsed before termination
183	dl	1.17	* @throws InterruptedException if interrupted while waiting
184			*/
185			boolean awaitTermination(long timeout, TimeUnit unit)
186			throws InterruptedException;
187
188
189	tim	1.8	/**
190	dl	1.30	* Submits a value-returning task for execution and returns a
191	dl	1.31	* Future representing the pending results of the task. The
192	dl	1.32	* Future's <tt>get</tt> method will return the task's result upon
193	jsr166	1.37	* successful completion.
194	tim	1.8	*
195	dl	1.19	* <p>
196	dl	1.20	* If you would like to immediately block waiting
197	dl	1.19	* for a task, you can use constructions of the form
198			* <tt>result = exec.submit(aCallable).get();</tt>
199	dl	1.20	*
200			* <p> Note: The {@link Executors} class includes a set of methods
201			* that can convert some other common closure-like objects,
202			* for example, {@link java.security.PrivilegedAction} to
203			* {@link Callable} form so they can be submitted.
204			*
205	tim	1.8	* @param task the task to submit
206			* @return a Future representing pending completion of the task
207	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
208			* scheduled for execution
209			* @throws NullPointerException if the task is null
210	tim	1.8	*/
211			<T> Future<T> submit(Callable<T> task);
212
213			/**
214	dl	1.30	* Submits a Runnable task for execution and returns a Future
215	jsr166	1.33	* representing that task. The Future's <tt>get</tt> method will
216	dl	1.31	* return the given result upon successful completion.
217	dl	1.20	*
218			* @param task the task to submit
219			* @param result the result to return
220	dl	1.31	* @return a Future representing pending completion of the task
221	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
222			* scheduled for execution
223			* @throws NullPointerException if the task is null
224	dl	1.20	*/
225			<T> Future<T> submit(Runnable task, T result);
226
227			/**
228	jsr166	1.33	* Submits a Runnable task for execution and returns a Future
229			* representing that task. The Future's <tt>get</tt> method will
230	jsr166	1.37	* return <tt>null</tt> upon <em>successful</em> completion.
231	dl	1.1	*
232	dl	1.17	* @param task the task to submit
233	dl	1.31	* @return a Future representing pending completion of the task
234	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
235			* scheduled for execution
236			* @throws NullPointerException if the task is null
237	dl	1.1	*/
238	dl	1.18	Future<?> submit(Runnable task);
239	dl	1.15
240	dl	1.11	/**
241	dl	1.27	* Executes the given tasks, returning a list of Futures holding
242	jsr166	1.33	* their status and results when all complete.
243			* {@link Future#isDone} is <tt>true</tt> for each
244	dl	1.27	* element of the returned list.
245	dl	1.12	* Note that a <em>completed</em> task could have
246			* terminated either normally or by throwing an exception.
247	dl	1.21	* The results of this method are undefined if the given
248			* collection is modified while this operation is in progress.
249	jsr166	1.37	*
250	dl	1.11	* @param tasks the collection of tasks
251	dl	1.13	* @return A list of Futures representing the tasks, in the same
252	jsr166	1.37	* sequential order as produced by the iterator for the
253			* given task list, each of which has completed.
254	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
255	jsr166	1.37	* which case unfinished tasks are cancelled.
256	dl	1.13	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
257	jsr166	1.37	* @throws RejectedExecutionException if any task cannot be
258			* scheduled for execution
259	dl	1.11	*/
260	jsr166	1.38
261			<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
262	dl	1.11	throws InterruptedException;
263
264			/**
265	dl	1.27	* Executes the given tasks, returning a list of Futures holding
266	jsr166	1.33	* their status and results
267	dl	1.15	* when all complete or the timeout expires, whichever happens first.
268	jsr166	1.33	* {@link Future#isDone} is <tt>true</tt> for each
269	dl	1.27	* element of the returned list.
270	dl	1.11	* Upon return, tasks that have not completed are cancelled.
271	dl	1.12	* Note that a <em>completed</em> task could have
272			* terminated either normally or by throwing an exception.
273	dl	1.21	* The results of this method are undefined if the given
274			* collection is modified while this operation is in progress.
275	jsr166	1.37	*
276	dl	1.11	* @param tasks the collection of tasks
277			* @param timeout the maximum time to wait
278	dl	1.15	* @param unit the time unit of the timeout argument
279	jsr166	1.37	* @return a list of Futures representing the tasks, in the same
280			* sequential order as produced by the iterator for the
281			* given task list. If the operation did not time out,
282			* each task will have completed. If it did time out, some
283			* of these tasks will not have completed.
284	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
285	jsr166	1.37	* which case unfinished tasks are cancelled
286	dl	1.17	* @throws NullPointerException if tasks, any of its elements, or
287	jsr166	1.37	* unit are <tt>null</tt>
288	dl	1.13	* @throws RejectedExecutionException if any task cannot be scheduled
289	jsr166	1.37	* for execution
290	dl	1.11	*/
291	jsr166	1.38	<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
292	jsr166	1.33	long timeout, TimeUnit unit)
293	dl	1.11	throws InterruptedException;
294
295			/**
296	dl	1.17	* Executes the given tasks, returning the result
297	dl	1.15	* of one that has completed successfully (i.e., without throwing
298			* an exception), if any do. Upon normal or exceptional return,
299			* tasks that have not completed are cancelled.
300	dl	1.21	* The results of this method are undefined if the given
301			* collection is modified while this operation is in progress.
302	jsr166	1.37	*
303	dl	1.11	* @param tasks the collection of tasks
304	jsr166	1.37	* @return the result returned by one of the tasks
305	dl	1.15	* @throws InterruptedException if interrupted while waiting
306	jsr166	1.50	* @throws NullPointerException if tasks or any element task
307			* subject to execution is <tt>null</tt>
308	jsr166	1.37	* @throws IllegalArgumentException if tasks is empty
309	dl	1.15	* @throws ExecutionException if no task successfully completes
310			* @throws RejectedExecutionException if tasks cannot be scheduled
311	jsr166	1.37	* for execution
312	dl	1.11	*/
313	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks)
314	dl	1.15	throws InterruptedException, ExecutionException;
315	dl	1.11
316			/**
317	dl	1.17	* Executes the given tasks, returning the result
318	dl	1.15	* of one that has completed successfully (i.e., without throwing
319			* an exception), if any do before the given timeout elapses.
320			* Upon normal or exceptional return, tasks that have not
321			* completed are cancelled.
322	dl	1.21	* The results of this method are undefined if the given
323			* collection is modified while this operation is in progress.
324	jsr166	1.37	*
325	dl	1.11	* @param tasks the collection of tasks
326			* @param timeout the maximum time to wait
327			* @param unit the time unit of the timeout argument
328	jsr166	1.37	* @return the result returned by one of the tasks.
329	dl	1.15	* @throws InterruptedException if interrupted while waiting
330	jsr166	1.50	* @throws NullPointerException if tasks, or unit, or any element
331			* task subject to execution is <tt>null</tt>
332	dl	1.15	* @throws TimeoutException if the given timeout elapses before
333	jsr166	1.37	* any task successfully completes
334	dl	1.15	* @throws ExecutionException if no task successfully completes
335			* @throws RejectedExecutionException if tasks cannot be scheduled
336	jsr166	1.37	* for execution
337	dl	1.11	*/
338	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks,
339	jsr166	1.33	long timeout, TimeUnit unit)
340	dl	1.15	throws InterruptedException, ExecutionException, TimeoutException;
341	dl	1.1	}