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;

/**
 * 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 {@code ExecutorService} can be shut down, which will cause
 * it to reject new tasks.  Two different methods are provided for
 * shutting down an {@code ExecutorService}. 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 {@code ExecutorService} should be shut down to allow
 * reclamation of its resources.
 *
 * <p>Method {@code submit} 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 {@code invokeAny} and {@code invokeAll} 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> {@code
 * 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 {@code ExecutorService} in two phases,
 * first by calling {@code shutdown} to reject incoming tasks, and then
 * calling {@code shutdownNow}, if necessary, to cancel any lingering tasks:
 *
 *  <pre> {@code
 * 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}{@code ("modifyThread")},
     *         or the security manager's {@code checkAccess} 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}{@code ("modifyThread")},
     *         or the security manager's {@code checkAccess} method
     *         denies access.
     */
    List<Runnable> shutdownNow();

    /**
     * Returns {@code true} if this executor has been shut down.
     *
     * @return {@code true} if this executor has been shut down
     */
    boolean isShutdown();

    /**
     * Returns {@code true} if all tasks have completed following shut down.
     * Note that {@code isTerminated} is never {@code true} unless
     * either {@code shutdown} or {@code shutdownNow} was called first.
     *
     * @return {@code true} 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 {@code true} if this executor terminated and
     *         {@code false} 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 {@code get} 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
     * {@code result = exec.submit(aCallable).get();}
     *
     * <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 {@code get} 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 {@code get} method will
     * return {@code null} 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 {@code true} 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 {@code null}
     * @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 {@code true} 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 {@code null}
     * @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 {@code null}
     * @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 {@code null}
     * @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:	1.58
Committed:	Wed Jan 16 01:59:47 2013 UTC (11 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.57:	+31 -31 lines
Log Message:	<tt> -> {@code
#	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	dl	1.1
11			/**
12	dl	1.25	* An {@link Executor} that provides methods to manage termination and
13	dl	1.20	* methods that can produce a {@link Future} for tracking progress of
14	jsr166	1.33	* one or more asynchronous tasks.
15	dl	1.17	*
16	jsr166	1.58	* <p>An {@code ExecutorService} can be shut down, which will cause
17	dl	1.47	* it to reject new tasks. Two different methods are provided for
18	jsr166	1.58	* shutting down an {@code ExecutorService}. The {@link #shutdown}
19	dl	1.47	* method will allow previously submitted tasks to execute before
20			* terminating, while the {@link #shutdownNow} method prevents waiting
21			* tasks from starting and attempts to stop currently executing tasks.
22			* Upon termination, an executor has no tasks actively executing, no
23			* tasks awaiting execution, and no new tasks can be submitted. An
24	jsr166	1.58	* unused {@code ExecutorService} should be shut down to allow
25	dl	1.47	* reclamation of its resources.
26	dl	1.1	*
27	jsr166	1.58	* <p>Method {@code submit} extends base method {@link
28	dl	1.20	* Executor#execute} by creating and returning a {@link Future} that
29			* can be used to cancel execution and/or wait for completion.
30	jsr166	1.58	* Methods {@code invokeAny} and {@code invokeAll} perform the most
31	dl	1.20	* commonly useful forms of bulk execution, executing a collection of
32			* tasks and then waiting for at least one, or all, to
33			* complete. (Class {@link ExecutorCompletionService} can be used to
34			* write customized variants of these methods.)
35	dl	1.17	*
36	dl	1.7	* <p>The {@link Executors} class provides factory methods for the
37			* executor services provided in this package.
38	dl	1.1	*
39	dl	1.47	* <h3>Usage Examples</h3>
40	dl	1.23	*
41			* Here is a sketch of a network service in which threads in a thread
42			* pool service incoming requests. It uses the preconfigured {@link
43			* Executors#newFixedThreadPool} factory method:
44			*
45	jsr166	1.53	* <pre> {@code
46	dl	1.47	* class NetworkService implements Runnable {
47	jsr166	1.37	* private final ServerSocket serverSocket;
48			* private final ExecutorService pool;
49	dl	1.23	*
50	jsr166	1.37	* public NetworkService(int port, int poolSize)
51			* throws IOException {
52			* serverSocket = new ServerSocket(port);
53			* pool = Executors.newFixedThreadPool(poolSize);
54			* }
55	jsr166	1.33	*
56	dl	1.47	* public void run() { // run the service
57	jsr166	1.37	* try {
58			* for (;;) {
59			* pool.execute(new Handler(serverSocket.accept()));
60			* }
61			* } catch (IOException ex) {
62			* pool.shutdown();
63			* }
64			* }
65			* }
66	dl	1.23	*
67	jsr166	1.37	* class Handler implements Runnable {
68			* private final Socket socket;
69			* Handler(Socket socket) { this.socket = socket; }
70			* public void run() {
71	dl	1.47	* // read and service request on socket
72			* }
73	jsr166	1.53	* }}</pre>
74	dl	1.47	*
75	jsr166	1.58	* The following method shuts down an {@code ExecutorService} in two phases,
76			* first by calling {@code shutdown} to reject incoming tasks, and then
77			* calling {@code shutdownNow}, if necessary, to cancel any lingering tasks:
78	dl	1.47	*
79	jsr166	1.53	* <pre> {@code
80	dl	1.47	* void shutdownAndAwaitTermination(ExecutorService pool) {
81			* pool.shutdown(); // Disable new tasks from being submitted
82			* try {
83			* // Wait a while for existing tasks to terminate
84			* if (!pool.awaitTermination(60, TimeUnit.SECONDS)) {
85			* pool.shutdownNow(); // Cancel currently executing tasks
86			* // Wait a while for tasks to respond to being cancelled
87			* if (!pool.awaitTermination(60, TimeUnit.SECONDS))
88			* System.err.println("Pool did not terminate");
89			* }
90			* } catch (InterruptedException ie) {
91	jsr166	1.48	* // (Re-)Cancel if current thread also interrupted
92			* pool.shutdownNow();
93			* // Preserve interrupt status
94			* Thread.currentThread().interrupt();
95	jsr166	1.37	* }
96	jsr166	1.53	* }}</pre>
97	brian	1.40	*
98	jsr166	1.43	* <p>Memory consistency effects: Actions in a thread prior to the
99			* submission of a {@code Runnable} or {@code Callable} task to an
100			* {@code ExecutorService}
101			* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
102			* any actions taken by that task, which in turn <i>happen-before</i> the
103			* result is retrieved via {@code Future.get()}.
104	brian	1.40	*
105	dl	1.1	* @since 1.5
106	dl	1.5	* @author Doug Lea
107	dl	1.1	*/
108			public interface ExecutorService extends Executor {
109	tim	1.8
110	dl	1.17	/**
111			* Initiates an orderly shutdown in which previously submitted
112	jsr166	1.37	* tasks are executed, but no new tasks will be accepted.
113			* Invocation has no additional effect if already shut down.
114			*
115	jsr166	1.49	* <p>This method does not wait for previously submitted tasks to
116			* complete execution. Use {@link #awaitTermination awaitTermination}
117			* to do that.
118			*
119	dl	1.17	* @throws SecurityException if a security manager exists and
120	jsr166	1.37	* shutting down this ExecutorService may manipulate
121			* threads that the caller is not permitted to modify
122			* because it does not hold {@link
123	jsr166	1.58	* java.lang.RuntimePermission}{@code ("modifyThread")},
124			* or the security manager's {@code checkAccess} method
125	jsr166	1.37	* denies access.
126	dl	1.17	*/
127			void shutdown();
128
129			/**
130			* Attempts to stop all actively executing tasks, halts the
131	jsr166	1.49	* processing of waiting tasks, and returns a list of the tasks
132			* that were awaiting execution.
133			*
134			* <p>This method does not wait for actively executing tasks to
135			* terminate. Use {@link #awaitTermination awaitTermination} to
136			* do that.
137	jsr166	1.33	*
138	dl	1.17	* <p>There are no guarantees beyond best-effort attempts to stop
139			* processing actively executing tasks. For example, typical
140	jsr166	1.39	* implementations will cancel via {@link Thread#interrupt}, so any
141			* task that fails to respond to interrupts may never terminate.
142	dl	1.17	*
143			* @return list of tasks that never commenced execution
144			* @throws SecurityException if a security manager exists and
145	jsr166	1.37	* shutting down this ExecutorService may manipulate
146			* threads that the caller is not permitted to modify
147			* because it does not hold {@link
148	jsr166	1.58	* java.lang.RuntimePermission}{@code ("modifyThread")},
149			* or the security manager's {@code checkAccess} method
150	jsr166	1.37	* denies access.
151	dl	1.17	*/
152			List<Runnable> shutdownNow();
153
154			/**
155	jsr166	1.58	* Returns {@code true} if this executor has been shut down.
156	dl	1.17	*
157	jsr166	1.58	* @return {@code true} if this executor has been shut down
158	dl	1.17	*/
159			boolean isShutdown();
160
161			/**
162	jsr166	1.58	* Returns {@code true} if all tasks have completed following shut down.
163			* Note that {@code isTerminated} is never {@code true} unless
164			* either {@code shutdown} or {@code shutdownNow} was called first.
165	dl	1.17	*
166	jsr166	1.58	* @return {@code true} if all tasks have completed following shut down
167	dl	1.17	*/
168			boolean isTerminated();
169
170			/**
171			* Blocks until all tasks have completed execution after a shutdown
172			* request, or the timeout occurs, or the current thread is
173	jsr166	1.36	* interrupted, whichever happens first.
174	dl	1.17	*
175			* @param timeout the maximum time to wait
176			* @param unit the time unit of the timeout argument
177	jsr166	1.58	* @return {@code true} if this executor terminated and
178			* {@code false} if the timeout elapsed before termination
179	dl	1.17	* @throws InterruptedException if interrupted while waiting
180			*/
181			boolean awaitTermination(long timeout, TimeUnit unit)
182			throws InterruptedException;
183
184	tim	1.8	/**
185	dl	1.30	* Submits a value-returning task for execution and returns a
186	dl	1.31	* Future representing the pending results of the task. The
187	jsr166	1.58	* Future's {@code get} method will return the task's result upon
188	jsr166	1.37	* successful completion.
189	tim	1.8	*
190	dl	1.19	* <p>
191	dl	1.20	* If you would like to immediately block waiting
192	dl	1.19	* for a task, you can use constructions of the form
193	jsr166	1.58	* {@code result = exec.submit(aCallable).get();}
194	dl	1.20	*
195	jsr166	1.56	* <p>Note: The {@link Executors} class includes a set of methods
196	dl	1.20	* that can convert some other common closure-like objects,
197			* for example, {@link java.security.PrivilegedAction} to
198			* {@link Callable} form so they can be submitted.
199			*
200	tim	1.8	* @param task the task to submit
201			* @return a Future representing pending completion of the task
202	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
203			* scheduled for execution
204			* @throws NullPointerException if the task is null
205	tim	1.8	*/
206			<T> Future<T> submit(Callable<T> task);
207
208			/**
209	dl	1.30	* Submits a Runnable task for execution and returns a Future
210	jsr166	1.58	* representing that task. The Future's {@code get} method will
211	dl	1.31	* return the given result upon successful completion.
212	dl	1.20	*
213			* @param task the task to submit
214			* @param result the result to return
215	dl	1.31	* @return a Future representing pending completion of the task
216	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
217			* scheduled for execution
218			* @throws NullPointerException if the task is null
219	dl	1.20	*/
220			<T> Future<T> submit(Runnable task, T result);
221
222			/**
223	jsr166	1.33	* Submits a Runnable task for execution and returns a Future
224	jsr166	1.58	* representing that task. The Future's {@code get} method will
225			* return {@code null} upon <em>successful</em> completion.
226	dl	1.1	*
227	dl	1.17	* @param task the task to submit
228	dl	1.31	* @return a Future representing pending completion of the task
229	jsr166	1.37	* @throws RejectedExecutionException if the task cannot be
230			* scheduled for execution
231			* @throws NullPointerException if the task is null
232	dl	1.1	*/
233	dl	1.18	Future<?> submit(Runnable task);
234	dl	1.15
235	dl	1.11	/**
236	dl	1.27	* Executes the given tasks, returning a list of Futures holding
237	jsr166	1.33	* their status and results when all complete.
238	jsr166	1.58	* {@link Future#isDone} is {@code true} for each
239	dl	1.27	* element of the returned list.
240	dl	1.12	* Note that a <em>completed</em> task could have
241			* terminated either normally or by throwing an exception.
242	dl	1.21	* The results of this method are undefined if the given
243			* collection is modified while this operation is in progress.
244	jsr166	1.37	*
245	dl	1.11	* @param tasks the collection of tasks
246	dl	1.13	* @return A list of Futures representing the tasks, in the same
247	jsr166	1.37	* sequential order as produced by the iterator for the
248			* given task list, each of which has completed.
249	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
250	jsr166	1.37	* which case unfinished tasks are cancelled.
251	jsr166	1.58	* @throws NullPointerException if tasks or any of its elements are {@code null}
252	jsr166	1.37	* @throws RejectedExecutionException if any task cannot be
253			* scheduled for execution
254	dl	1.11	*/
255	jsr166	1.38	<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
256	dl	1.11	throws InterruptedException;
257
258			/**
259	dl	1.27	* Executes the given tasks, returning a list of Futures holding
260	jsr166	1.33	* their status and results
261	dl	1.15	* when all complete or the timeout expires, whichever happens first.
262	jsr166	1.58	* {@link Future#isDone} is {@code true} for each
263	dl	1.27	* element of the returned list.
264	dl	1.11	* Upon return, tasks that have not completed are cancelled.
265	dl	1.12	* Note that a <em>completed</em> task could have
266			* terminated either normally or by throwing an exception.
267	dl	1.21	* The results of this method are undefined if the given
268			* collection is modified while this operation is in progress.
269	jsr166	1.37	*
270	dl	1.11	* @param tasks the collection of tasks
271			* @param timeout the maximum time to wait
272	dl	1.15	* @param unit the time unit of the timeout argument
273	jsr166	1.37	* @return a list of Futures representing the tasks, in the same
274			* sequential order as produced by the iterator for the
275			* given task list. If the operation did not time out,
276			* each task will have completed. If it did time out, some
277			* of these tasks will not have completed.
278	dl	1.11	* @throws InterruptedException if interrupted while waiting, in
279	jsr166	1.37	* which case unfinished tasks are cancelled
280	dl	1.17	* @throws NullPointerException if tasks, any of its elements, or
281	jsr166	1.58	* unit are {@code null}
282	dl	1.13	* @throws RejectedExecutionException if any task cannot be scheduled
283	jsr166	1.37	* for execution
284	dl	1.11	*/
285	jsr166	1.38	<T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
286	jsr166	1.33	long timeout, TimeUnit unit)
287	dl	1.11	throws InterruptedException;
288
289			/**
290	dl	1.17	* Executes the given tasks, returning the result
291	dl	1.15	* of one that has completed successfully (i.e., without throwing
292			* an exception), if any do. Upon normal or exceptional return,
293			* tasks that have not completed are cancelled.
294	dl	1.21	* The results of this method are undefined if the given
295			* collection is modified while this operation is in progress.
296	jsr166	1.37	*
297	dl	1.11	* @param tasks the collection of tasks
298	jsr166	1.37	* @return the result returned by one of the tasks
299	dl	1.15	* @throws InterruptedException if interrupted while waiting
300	jsr166	1.50	* @throws NullPointerException if tasks or any element task
301	jsr166	1.58	* subject to execution is {@code null}
302	jsr166	1.37	* @throws IllegalArgumentException if tasks is empty
303	dl	1.15	* @throws ExecutionException if no task successfully completes
304			* @throws RejectedExecutionException if tasks cannot be scheduled
305	jsr166	1.37	* for execution
306	dl	1.11	*/
307	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks)
308	dl	1.15	throws InterruptedException, ExecutionException;
309	dl	1.11
310			/**
311	dl	1.17	* Executes the given tasks, returning the result
312	dl	1.15	* of one that has completed successfully (i.e., without throwing
313			* an exception), if any do before the given timeout elapses.
314			* Upon normal or exceptional return, tasks that have not
315			* completed are cancelled.
316	dl	1.21	* The results of this method are undefined if the given
317			* collection is modified while this operation is in progress.
318	jsr166	1.37	*
319	dl	1.11	* @param tasks the collection of tasks
320			* @param timeout the maximum time to wait
321			* @param unit the time unit of the timeout argument
322	jsr166	1.57	* @return the result returned by one of the tasks
323	dl	1.15	* @throws InterruptedException if interrupted while waiting
324	jsr166	1.50	* @throws NullPointerException if tasks, or unit, or any element
325	jsr166	1.58	* task subject to execution is {@code null}
326	dl	1.15	* @throws TimeoutException if the given timeout elapses before
327	jsr166	1.37	* any task successfully completes
328	dl	1.15	* @throws ExecutionException if no task successfully completes
329			* @throws RejectedExecutionException if tasks cannot be scheduled
330	jsr166	1.37	* for execution
331	dl	1.11	*/
332	jsr166	1.38	<T> T invokeAny(Collection<? extends Callable<T>> tasks,
333	jsr166	1.33	long timeout, TimeUnit unit)
334	dl	1.15	throws InterruptedException, ExecutionException, TimeoutException;
335	dl	1.1	}