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

/**
 * An <tt>Executor</tt> 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.
 *
 * <p> Method <tt>submit</tt> extends base method <tt>execute</tt> 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 customizable
 * versions of such methods.)
 *
 * <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 {


    /**
     * 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 if any
     * tasks mask or fail to respond to interrupts, they 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. 
     *
     * <p>
     * Note that 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>
     * @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);

    /**
     * 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 <tt>null</tt>
     * upon completion.
     * @throws RejectedExecutionException if task cannot be scheduled
     * for execution
     */
    Future<?> submit(Runnable task);

    /**
     * Executes 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 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<Callable<T>> tasks)
        throws InterruptedException;

    /**
     * Executes 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 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 thiese 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<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.
     * @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 empty
     * @throws ExecutionException if no task successfully completes
     * @throws RejectedExecutionException if tasks cannot be scheduled
     * for execution
     */
    <T> T invokeAny(Collection<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.
     * @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<Callable<T>> tasks, 
                    long timeout, TimeUnit unit) 
        throws InterruptedException, ExecutionException, TimeoutException;

}
Revision:	1.19
Committed:	Sat Dec 20 14:00:05 2003 UTC (20 years, 5 months ago) by dl
Branch:	MAIN
Changes since 1.18:	+5 -16 lines
Log Message:	Replace PrivilegedFutureTask with Executors.privilegedCallable
#	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.util.Collection;
11	import java.security.PrivilegedAction;
12	import java.security.PrivilegedExceptionAction;
13
14	/**
15	* An <tt>Executor</tt> that provides methods to manage termination
16	* and methods that can produce a {@link Future} for tracking
17	* progress of one or more asynchronous tasks.
18	* <p>
19	*
20	* An <tt>ExecutorService</tt> can be shut down, which will cause it
21	* to stop accepting new tasks. After being shut down, the executor
22	* will eventually terminate, at which point no tasks are actively
23	* executing, no tasks are awaiting execution, and no new tasks can be
24	* submitted.
25	*
26	* <p> Method <tt>submit</tt> extends base method <tt>execute</tt> by
27	* creating and returning a {@link Future} that can be used to cancel
28	* execution and/or wait for completion. Methods <tt>invokeAny</tt>
29	* and <tt>invokeAll</tt> perform the most commonly useful forms of
30	* bulk execution, executing a collection of tasks and then waiting
31	* for at least one, or all to complete. (Class {@link
32	* ExecutorCompletionService} can be used to write customizable
33	* versions of such methods.)
34	*
35	* <p>The {@link Executors} class provides factory methods for the
36	* executor services provided in this package.
37	*
38	* @since 1.5
39	* @author Doug Lea
40	*/
41	public interface ExecutorService extends Executor {
42
43
44	/**
45	* Initiates an orderly shutdown in which previously submitted
46	* tasks are executed, but no new tasks will be
47	* accepted. Invocation has no additional effect if already shut
48	* down.
49	* @throws SecurityException if a security manager exists and
50	* shutting down this ExecutorService may manipulate threads that
51	* the caller is not permitted to modify because it does not hold
52	* {@link java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
53	* or the security manager's <tt>checkAccess</tt> method denies access.
54	*/
55	void shutdown();
56
57	/**
58	* Attempts to stop all actively executing tasks, halts the
59	* processing of waiting tasks, and returns a list of the tasks that were
60	* awaiting execution.
61	*
62	* <p>There are no guarantees beyond best-effort attempts to stop
63	* processing actively executing tasks. For example, typical
64	* implementations will cancel via {@link Thread#interrupt}, so if any
65	* tasks mask or fail to respond to interrupts, they may never terminate.
66	*
67	* @return list of tasks that never commenced execution
68	* @throws SecurityException if a security manager exists and
69	* shutting down this ExecutorService may manipulate threads that
70	* the caller is not permitted to modify because it does not hold
71	* {@link java.lang.RuntimePermission}<tt>("modifyThread")</tt>,
72	* or the security manager's <tt>checkAccess</tt> method denies access.
73	*/
74	List<Runnable> shutdownNow();
75
76	/**
77	* Returns <tt>true</tt> if this executor has been shut down.
78	*
79	* @return <tt>true</tt> if this executor has been shut down
80	*/
81	boolean isShutdown();
82
83	/**
84	* Returns <tt>true</tt> if all tasks have completed following shut down.
85	* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
86	* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
87	*
88	* @return <tt>true</tt> if all tasks have completed following shut down
89	*/
90	boolean isTerminated();
91
92	/**
93	* Blocks until all tasks have completed execution after a shutdown
94	* request, or the timeout occurs, or the current thread is
95	* interrupted, whichever happens first.
96	*
97	* @param timeout the maximum time to wait
98	* @param unit the time unit of the timeout argument
99	* @return <tt>true</tt> if this executor terminated and <tt>false</tt>
100	* if the timeout elapsed before termination
101	* @throws InterruptedException if interrupted while waiting
102	*/
103	boolean awaitTermination(long timeout, TimeUnit unit)
104	throws InterruptedException;
105
106
107	/**
108	* Submits a value-returning task for execution and returns a Future
109	* representing the pending results of the task.
110	*
111	* <p>
112	* Note that if you would like to immediately block waiting
113	* for a task, you can use constructions of the form
114	* <tt>result = exec.submit(aCallable).get();</tt>
115	* @param task the task to submit
116	* @return a Future representing pending completion of the task
117	* @throws RejectedExecutionException if task cannot be scheduled
118	* for execution
119	*/
120	<T> Future<T> submit(Callable<T> task);
121
122	/**
123	* Submits a Runnable task for execution and returns a Future
124	* representing that task.
125	*
126	* @param task the task to submit
127	* @return a Future representing pending completion of the task,
128	* and whose <tt>get()</tt> method will return <tt>null</tt>
129	* upon completion.
130	* @throws RejectedExecutionException if task cannot be scheduled
131	* for execution
132	*/
133	Future<?> submit(Runnable task);
134
135	/**
136	* Executes the given tasks, returning their results
137	* when all complete.
138	* Note that a <em>completed</em> task could have
139	* terminated either normally or by throwing an exception.
140	* @param tasks the collection of tasks
141	* @return A list of Futures representing the tasks, in the same
142	* sequential order as produced by the iterator for the given task list, each of which has
143	* completed.
144	* @throws InterruptedException if interrupted while waiting, in
145	* which case unfinished tasks are cancelled.
146	* @throws NullPointerException if tasks or any of its elements are <tt>null</tt>
147	* @throws RejectedExecutionException if any task cannot be scheduled
148	* for execution
149	*/
150
151	<T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks)
152	throws InterruptedException;
153
154	/**
155	* Executes the given tasks, returning their results
156	* when all complete or the timeout expires, whichever happens first.
157	* Upon return, tasks that have not completed are cancelled.
158	* Note that a <em>completed</em> task could have
159	* terminated either normally or by throwing an exception.
160	* @param tasks the collection of tasks
161	* @param timeout the maximum time to wait
162	* @param unit the time unit of the timeout argument
163	* @return A list of Futures representing the tasks, in the same
164	* sequential order as as produced by the iterator for the given task list. If the operation did
165	* not time out, each task will have completed. If it did time
166	* out, some of thiese tasks will not have completed.
167	* @throws InterruptedException if interrupted while waiting, in
168	* which case unfinished tasks are cancelled.
169	* @throws NullPointerException if tasks, any of its elements, or
170	* unit are <tt>null</tt>
171	* @throws RejectedExecutionException if any task cannot be scheduled
172	* for execution
173	*/
174	<T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks,
175	long timeout, TimeUnit unit)
176	throws InterruptedException;
177
178	/**
179	* Executes the given tasks, returning the result
180	* of one that has completed successfully (i.e., without throwing
181	* an exception), if any do. Upon normal or exceptional return,
182	* tasks that have not completed are cancelled.
183	* @param tasks the collection of tasks
184	* @return The result returned by one of the tasks.
185	* @throws InterruptedException if interrupted while waiting
186	* @throws NullPointerException if tasks or any of its elements
187	* are <tt>null</tt>
188	* @throws IllegalArgumentException if tasks empty
189	* @throws ExecutionException if no task successfully completes
190	* @throws RejectedExecutionException if tasks cannot be scheduled
191	* for execution
192	*/
193	<T> T invokeAny(Collection<Callable<T>> tasks)
194	throws InterruptedException, ExecutionException;
195
196	/**
197	* Executes the given tasks, returning the result
198	* of one that has completed successfully (i.e., without throwing
199	* an exception), if any do before the given timeout elapses.
200	* Upon normal or exceptional return, tasks that have not
201	* completed are cancelled.
202	* @param tasks the collection of tasks
203	* @param timeout the maximum time to wait
204	* @param unit the time unit of the timeout argument
205	* @return The result returned by one of the tasks.
206	* @throws InterruptedException if interrupted while waiting
207	* @throws NullPointerException if tasks, any of its elements, or
208	* unit are <tt>null</tt>
209	* @throws TimeoutException if the given timeout elapses before
210	* any task successfully completes
211	* @throws ExecutionException if no task successfully completes
212	* @throws RejectedExecutionException if tasks cannot be scheduled
213	* for execution
214	*/
215	<T> T invokeAny(Collection<Callable<T>> tasks,
216	long timeout, TimeUnit unit)
217	throws InterruptedException, ExecutionException, TimeoutException;
218
219	}