util/concurrent/ExecutorService.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain. Use, modify, and
 * redistribute this code in any way without acknowledgement.
 */

package java.util.concurrent;

import java.util.List;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;

/**
 * An <tt>Executor</tt> that provides methods to manage termination
 * and those that can produce a {@link Future} for tracking
 * progress of one or more asynchronous tasks.
 * 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.
 *
 * <p>The {@link Executors} class provides factory methods for the
 * executor services provided in this package.
 *
 * @since 1.5
 * @author Doug Lea
 */
public interface ExecutorService extends Executor {

    /**
     * Submits a Runnable task for execution and returns a Future 
     * representing that task.
     *
     * @param task the task to submit
     * @return a Future representing pending completion of the task,
     * and whose <tt>get()</tt> method will return an arbitrary value 
     * upon completion
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     */
    Future<?> submit(Runnable task);

    /**
     * Submits a value-returning task for execution and returns a Future
     * representing the pending results of the task.
     *
     * @param task the task to submit
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     */
    <T> Future<T> submit(Callable<T> task);

    /**
     * Executes a Runnable task and blocks until it completes normally
     * or throws an exception.
     *
     * @param task the task to submit
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     * @throws ExecutionException if the task encountered an exception
     * while executing
     */
    void invoke(Runnable task) throws ExecutionException, InterruptedException;

    /**
     * Executes a value-returning task and blocks until it returns a
     * value or throws an exception.
     *
     * @param task the task to submit
     * @return a Future representing pending completion of the task
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     * @throws InterruptedException if interrupted while waiting for
     * completion
     * @throws ExecutionException if the task encountered an exception
     * while executing
     */
    <T> T invoke(Callable<T> task) throws ExecutionException, InterruptedException;


    /**
     * Submits a privileged action for execution under the current 
     * access control context and returns a Future representing the 
     * pending result object of that action.
     *
     * @param action the action to submit
     * @return a Future representing pending completion of the action
     * @throws RejectedExecutionException if action cannot be scheduled
     * for execution
     */
    Future<Object> submit(PrivilegedAction action);

    /**
     * Submits a privileged exception action for execution under the current 
     * access control context and returns a Future representing the pending 
     * result object of that action.
     *
     * @param action the action to submit
     * @return a Future representing pending completion of the action
     * @throws RejectedExecutionException if action cannot be scheduled
     * for execution
     */
    Future<Object> submit(PrivilegedExceptionAction action);
    

    /**
     * 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.
     *
     */
    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 if any
     * tasks mask or fail to respond to interrupts, they may never terminate.
     *
     * @return list of tasks that never commenced execution
     */
    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;


    /**
     * Arranges for execution of the given tasks, returning when at
     * least one of them has completed. 
     * 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.
     * @param tasks the collection of tasks
     * @return A list of Futures representing the tasks, in the same
     * sequential order as the given task list. If the task list is
     * non-empty, at least one element of this list is known to have
     * completed. Other tasks may or may not have also 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
     */
    List<Future<?>> runAny(List<Runnable> tasks)
        throws InterruptedException;

    /**
     * Arranges for execution of the given tasks, returning when at
     * least one of them has completed or the given timeout expires.
     * 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.
     * @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 the given task list. If the task list is
     * non-empty and the operation did not time out, at least one
     * element of this list is known to have completed. Other tasks
     * may or may not have also completed.
     * @throws InterruptedException if interrupted while waiting, in
     * which case unfinished tasks are cancelled.
     * @throws NullPointerException if tasks, any or its elements, or unit are <tt>null</tt>
     * @throws RejectedExecutionException if any task cannot be scheduled
     * for execution
     */
    List<Future<?>> runAny(List<Runnable> tasks, 
                           long timeout, TimeUnit unit) 
        throws InterruptedException;


    /**
     * Arranges for execution of the given tasks, returning when
     * all of them complete. 
     * Note that a <em>completed</em> task could have
     * terminated either normally or by throwing an exception.
     * @param tasks the collection of tasks
     * @return A list of Futures representing the tasks, in the same
     * sequential order as 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
     */
    List<Future<?>> runAll(List<Runnable> tasks)
        throws InterruptedException;

    /**
     * Arranges for execution of the given tasks, returning normally
     * when all complete or the given timeout expires, whichever
     * happens first.
     * 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.
     * @param tasks the collection of tasks
     * @param timeout the maximum time to wait
     * @return A list of Futures representing the tasks, in the same
     * sequential order as 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.
     * @param unit the time unit of the timeout argument
     * @throws InterruptedException if interrupted while waiting, in
     * which case unfinished tasks are cancelled.
     * @throws NullPointerException if tasks, any or its elements, or unit are <tt>null</tt>
     * @throws RejectedExecutionException if any task cannot be scheduled
     * for execution
     */
    List<Future<?>> runAll(List<Runnable> tasks, 
                              long timeout, TimeUnit unit) 
        throws InterruptedException;

    /**
     * Arranges for execution of the given tasks, returning when at
     * least one of them has completed. 
     * 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.
     * @param tasks the collection of tasks
     * @return A list of Futures representing the tasks, in the same
     * sequential order as the given task list. If the task list is
     * non-empty, at least one task on this list is known to have
     * completed. Other tasks may or may not have also 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>> callAny(List<Callable<T>> tasks)
        throws InterruptedException;

    /**
     * Arranges for execution of the given tasks, returning when at
     * least one of them has completed or the given timeout expires.
     * 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.
     * @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 the given task list. If the task list is
     * non-empty and the operation did not time out, at least one task
     * on this list is known to have completed. Other tasks may or may
     * not have also completed. If the operation timed out, none of
     * the tasks will have completed.
     * @throws InterruptedException if interrupted while waiting, in
     * which case unfinished tasks are cancelled.
     * @throws NullPointerException if tasks, any or its elements, or unit are <tt>null</tt>
     * @throws RejectedExecutionException if any task cannot be scheduled
     * for execution
     */
    <T> List<Future<T>> callAny(List<Callable<T>> tasks, 
                                long timeout, TimeUnit unit) 
        throws InterruptedException;

    /**
     * Arranges for execution of the given tasks, returning their results
     * when all complete.
     * Note that a <em>completed</em> task could have
     * terminated either normally or by throwing an exception.
     * @param tasks the collection of tasks
     * @return A list of Futures representing the tasks, in the same
     * sequential order as 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>> callAll(List<Callable<T>> tasks)
        throws InterruptedException;

    /**
     * Arranges for execution of the given tasks, returning their results
     * when all complete or the timeout expires, whichever happens first.
     * 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.
     * @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 the given task list. If the operation did
     * not time out, each task will have completed. If it did time
     * out, some of thiese tasks will not have completed.
     * @throws InterruptedException if interrupted while waiting, in
     * which case unfinished tasks are cancelled.
     * @throws NullPointerException if tasks, any or its elements, or
     * unit are <tt>null</tt>
     * @throws RejectedExecutionException if any task cannot be scheduled
     * for execution
     */
    <T> List<Future<T>> callAll(List<Callable<T>> tasks, 
                                long timeout, TimeUnit unit) 
        throws InterruptedException;

}
Revision:	1.13
Committed:	Mon Dec 15 00:29:49 2003 UTC (20 years, 5 months ago) by dl
Branch:	MAIN
Changes since 1.12:	+65 -44 lines
Log Message:	Added CompletionService; Executor any/all methods now require lists
#	Content
1	/*
2	* Written by Doug Lea with assistance from members of JCP JSR-166
3	* Expert Group and released to the public domain. Use, modify, and
4	* redistribute this code in any way without acknowledgement.
5	*/
6
7	package java.util.concurrent;
8
9	import java.util.List;
10	import java.security.PrivilegedAction;
11	import java.security.PrivilegedExceptionAction;
12
13	/**
14	* An <tt>Executor</tt> that provides methods to manage termination
15	* and those that can produce a {@link Future} for tracking
16	* progress of one or more asynchronous tasks.
17	* An <tt>ExecutorService</tt> can be shut down, which will cause it
18	* to stop accepting new tasks. After being shut down, the executor
19	* will eventually terminate, at which point no tasks are actively
20	* executing, no tasks are awaiting execution, and no new tasks can be
21	* submitted.
22	*
23	* <p>The {@link Executors} class provides factory methods for the
24	* executor services provided in this package.
25	*
26	* @since 1.5
27	* @author Doug Lea
28	*/
29	public interface ExecutorService extends Executor {
30
31	/**
32	* Submits a Runnable task for execution and returns a Future
33	* representing that task.
34	*
35	* @param task the task to submit
36	* @return a Future representing pending completion of the task,
37	* and whose <tt>get()</tt> method will return an arbitrary value
38	* upon completion
39	* @throws RejectedExecutionException if task cannot be scheduled
40	* for execution
41	*/
42	Future<?> submit(Runnable task);
43
44	/**
45	* Submits a value-returning task for execution and returns a Future
46	* representing the pending results of the task.
47	*
48	* @param task the task to submit
49	* @return a Future representing pending completion of the task
50	* @throws RejectedExecutionException if task cannot be scheduled
51	* for execution
52	*/
53	<T> Future<T> submit(Callable<T> task);
54
55	/**
56	* Executes a Runnable task and blocks until it completes normally
57	* or throws an exception.
58	*
59	* @param task the task to submit
60	* @throws RejectedExecutionException if task cannot be scheduled
61	* for execution
62	* @throws ExecutionException if the task encountered an exception
63	* while executing
64	*/
65	void invoke(Runnable task) throws ExecutionException, InterruptedException;
66
67	/**
68	* Executes a value-returning task and blocks until it returns a
69	* value or throws an exception.
70	*
71	* @param task the task to submit
72	* @return a Future representing pending completion of the task
73	* @throws RejectedExecutionException if task cannot be scheduled
74	* for execution
75	* @throws InterruptedException if interrupted while waiting for
76	* completion
77	* @throws ExecutionException if the task encountered an exception
78	* while executing
79	*/
80	<T> T invoke(Callable<T> task) throws ExecutionException, InterruptedException;
81
82
83	/**
84	* Submits a privileged action for execution under the current
85	* access control context and returns a Future representing the
86	* pending result object of that action.
87	*
88	* @param action the action to submit
89	* @return a Future representing pending completion of the action
90	* @throws RejectedExecutionException if action cannot be scheduled
91	* for execution
92	*/
93	Future<Object> submit(PrivilegedAction action);
94
95	/**
96	* Submits a privileged exception action for execution under the current
97	* access control context and returns a Future representing the pending
98	* result object of that action.
99	*
100	* @param action the action to submit
101	* @return a Future representing pending completion of the action
102	* @throws RejectedExecutionException if action cannot be scheduled
103	* for execution
104	*/
105	Future<Object> submit(PrivilegedExceptionAction action);
106
107
108	/**
109	* Initiates an orderly shutdown in which previously submitted
110	* tasks are executed, but no new tasks will be
111	* accepted. Invocation has no additional effect if already shut
112	* down.
113	*
114	*/
115	void shutdown();
116
117	/**
118	* Attempts to stop all actively executing tasks, halts the
119	* processing of waiting tasks, and returns a list of the tasks that were
120	* awaiting execution.
121	*
122	* <p>There are no guarantees beyond best-effort attempts to stop
123	* processing actively executing tasks. For example, typical
124	* implementations will cancel via {@link Thread#interrupt}, so if any
125	* tasks mask or fail to respond to interrupts, they may never terminate.
126	*
127	* @return list of tasks that never commenced execution
128	*/
129	List<Runnable> shutdownNow();
130
131	/**
132	* Returns <tt>true</tt> if this executor has been shut down.
133	*
134	* @return <tt>true</tt> if this executor has been shut down
135	*/
136	boolean isShutdown();
137
138	/**
139	* Returns <tt>true</tt> if all tasks have completed following shut down.
140	* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
141	* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
142	*
143	* @return <tt>true</tt> if all tasks have completed following shut down
144	*/
145	boolean isTerminated();
146
147	/**
148	* Blocks until all tasks have completed execution after a shutdown
149	* request, or the timeout occurs, or the current thread is
150	* interrupted, whichever happens first.
151	*
152	* @param timeout the maximum time to wait
153	* @param unit the time unit of the timeout argument
154	* @return <tt>true</tt> if this executor terminated and <tt>false</tt>
155	* if the timeout elapsed before termination
156	* @throws InterruptedException if interrupted while waiting
157	*/
158	boolean awaitTermination(long timeout, TimeUnit unit)
159	throws InterruptedException;
160
161
162	/**
163	* Arranges for execution of the given tasks, returning when at
164	* least one of them has completed.
165	* Upon return, tasks that have not completed are cancelled.
166	* Note that a <em>completed</em> task could have
167	* terminated either normally or by throwing an exception.
168	* @param tasks the collection of tasks
169	* @return A list of Futures representing the tasks, in the same
170	* sequential order as the given task list. If the task list is
171	* non-empty, at least one element of this list is known to have
172	* completed. Other tasks may or may not have also completed.
173	* @throws InterruptedException if interrupted while waiting, in
174	* which case unfinished tasks are cancelled.
175	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
176	* @throws RejectedExecutionException if any task cannot be scheduled
177	* for execution
178	*/
179	List<Future<?>> runAny(List<Runnable> tasks)
180	throws InterruptedException;
181
182	/**
183	* Arranges for execution of the given tasks, returning when at
184	* least one of them has completed or the given timeout expires.
185	* Upon return, tasks that have not completed are cancelled.
186	* Note that a <em>completed</em> task could have
187	* terminated either normally or by throwing an exception.
188	* @param tasks the collection of tasks
189	* @param timeout the maximum time to wait
190	* @param unit the time unit of the timeout argument
191	* @return A list of Futures representing the tasks, in the same
192	* sequential order as the given task list. If the task list is
193	* non-empty and the operation did not time out, at least one
194	* element of this list is known to have completed. Other tasks
195	* may or may not have also completed.
196	* @throws InterruptedException if interrupted while waiting, in
197	* which case unfinished tasks are cancelled.
198	* @throws NullPointerException if tasks, any or its elements, or unit are <tt>null</tt>
199	* @throws RejectedExecutionException if any task cannot be scheduled
200	* for execution
201	*/
202	List<Future<?>> runAny(List<Runnable> tasks,
203	long timeout, TimeUnit unit)
204	throws InterruptedException;
205
206
207	/**
208	* Arranges for execution of the given tasks, returning when
209	* all of them complete.
210	* Note that a <em>completed</em> task could have
211	* terminated either normally or by throwing an exception.
212	* @param tasks the collection of tasks
213	* @return A list of Futures representing the tasks, in the same
214	* sequential order as the given task list, each of which has
215	* completed.
216	* @throws InterruptedException if interrupted while waiting, in
217	* which case unfinished tasks are cancelled.
218	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
219	* @throws RejectedExecutionException if any task cannot be scheduled
220	* for execution
221	*/
222	List<Future<?>> runAll(List<Runnable> tasks)
223	throws InterruptedException;
224
225	/**
226	* Arranges for execution of the given tasks, returning normally
227	* when all complete or the given timeout expires, whichever
228	* happens first.
229	* Upon return, tasks that have not completed are cancelled.
230	* Note that a <em>completed</em> task could have
231	* terminated either normally or by throwing an exception.
232	* @param tasks the collection of tasks
233	* @param timeout the maximum time to wait
234	* @return A list of Futures representing the tasks, in the same
235	* sequential order as the given task list. If the operation did
236	* not time out, each task will have completed. If it did time
237	* out, some of these tasks will not have completed.
238	* @param unit the time unit of the timeout argument
239	* @throws InterruptedException if interrupted while waiting, in
240	* which case unfinished tasks are cancelled.
241	* @throws NullPointerException if tasks, any or its elements, or unit are <tt>null</tt>
242	* @throws RejectedExecutionException if any task cannot be scheduled
243	* for execution
244	*/
245	List<Future<?>> runAll(List<Runnable> tasks,
246	long timeout, TimeUnit unit)
247	throws InterruptedException;
248
249	/**
250	* Arranges for execution of the given tasks, returning when at
251	* least one of them has completed.
252	* Upon return, tasks that have not completed are cancelled.
253	* Note that a <em>completed</em> task could have
254	* terminated either normally or by throwing an exception.
255	* @param tasks the collection of tasks
256	* @return A list of Futures representing the tasks, in the same
257	* sequential order as the given task list. If the task list is
258	* non-empty, at least one task on this list is known to have
259	* completed. Other tasks may or may not have also completed.
260	* @throws InterruptedException if interrupted while waiting, in
261	* which case unfinished tasks are cancelled.
262	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
263	* @throws RejectedExecutionException if any task cannot be scheduled
264	* for execution
265	*/
266
267	<T> List<Future<T>> callAny(List<Callable<T>> tasks)
268	throws InterruptedException;
269
270	/**
271	* Arranges for execution of the given tasks, returning when at
272	* least one of them has completed or the given timeout expires.
273	* Upon return, tasks that have not completed are cancelled.
274	* Note that a <em>completed</em> task could have
275	* terminated either normally or by throwing an exception.
276	* @param tasks the collection of tasks
277	* @param timeout the maximum time to wait
278	* @param unit the time unit of the timeout argument
279	* @return A list of Futures representing the tasks, in the same
280	* sequential order as the given task list. If the task list is
281	* non-empty and the operation did not time out, at least one task
282	* on this list is known to have completed. Other tasks may or may
283	* not have also completed. If the operation timed out, none of
284	* the tasks will have completed.
285	* @throws InterruptedException if interrupted while waiting, in
286	* which case unfinished tasks are cancelled.
287	* @throws NullPointerException if tasks, any or its elements, or unit are <tt>null</tt>
288	* @throws RejectedExecutionException if any task cannot be scheduled
289	* for execution
290	*/
291	<T> List<Future<T>> callAny(List<Callable<T>> tasks,
292	long timeout, TimeUnit unit)
293	throws InterruptedException;
294
295	/**
296	* Arranges for execution of the given tasks, returning their results
297	* when all complete.
298	* Note that a <em>completed</em> task could have
299	* terminated either normally or by throwing an exception.
300	* @param tasks the collection of tasks
301	* @return A list of Futures representing the tasks, in the same
302	* sequential order as the given task list, each of which has
303	* completed.
304	* @throws InterruptedException if interrupted while waiting, in
305	* which case unfinished tasks are cancelled.
306	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
307	* @throws RejectedExecutionException if any task cannot be scheduled
308	* for execution
309	*/
310
311	<T> List<Future<T>> callAll(List<Callable<T>> tasks)
312	throws InterruptedException;
313
314	/**
315	* Arranges for execution of the given tasks, returning their results
316	* when all complete or the timeout expires, whichever happens first.
317	* Upon return, tasks that have not completed are cancelled.
318	* Note that a <em>completed</em> task could have
319	* terminated either normally or by throwing an exception.
320	* @param tasks the collection of tasks
321	* @param timeout the maximum time to wait
322	* @param unit the time unit of the timeout argument
323	* @return A list of Futures representing the tasks, in the same
324	* sequential order as the given task list. If the operation did
325	* not time out, each task will have completed. If it did time
326	* out, some of thiese tasks will not have completed.
327	* @throws InterruptedException if interrupted while waiting, in
328	* which case unfinished tasks are cancelled.
329	* @throws NullPointerException if tasks, any or its elements, or
330	* unit are <tt>null</tt>
331	* @throws RejectedExecutionException if any task cannot be scheduled
332	* for execution
333	*/
334	<T> List<Future<T>> callAll(List<Callable<T>> tasks,
335	long timeout, TimeUnit unit)
336	throws InterruptedException;
337
338	}