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.
 * 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 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;

}
Revision:	1.8
Committed:	Wed Dec 10 01:51:11 2003 UTC (20 years, 5 months ago) by tim
Branch:	MAIN
CVS Tags:	JSR166_DEC9_POST_ES_SUBMIT
Changes since 1.7:	+79 -0 lines
Log Message:	Move and rename static Executors.execute/invoke to ExecutorService.submit/invoke, providing implementations in AbstractExecutorService (which TPE extends).
#	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	* An <tt>ExecutorService</tt> can be shut down, which will cause it
16	* to stop accepting new tasks. After being shut down, the executor
17	* will eventually terminate, at which point no tasks are actively
18	* executing, no tasks are awaiting execution, and no new tasks can be
19	* submitted.
20	*
21	* <p>The {@link Executors} class provides factory methods for the
22	* executor services provided in this package.
23	*
24	* @since 1.5
25	* @author Doug Lea
26	*/
27	public interface ExecutorService extends Executor {
28
29	/**
30	* Submits a Runnable task for execution and returns a Future
31	* representing that task.
32	*
33	* @param task the task to submit
34	* @return a Future representing pending completion of the task,
35	* and whose <tt>get()</tt> method will return an arbitrary value
36	* upon completion
37	* @throws RejectedExecutionException if task cannot be scheduled
38	* for execution
39	*/
40	Future<?> submit(Runnable task);
41
42	/**
43	* Submits a value-returning task for execution and returns a Future
44	* representing the pending results of the task.
45	*
46	* @param task the task to submit
47	* @return a Future representing pending completion of the task
48	* @throws RejectedExecutionException if task cannot be scheduled
49	* for execution
50	*/
51	<T> Future<T> submit(Callable<T> task);
52
53	/**
54	* Executes a Runnable task and blocks until it completes normally
55	* or throws an exception.
56	*
57	* @param task the task to submit
58	* @throws RejectedExecutionException if task cannot be scheduled
59	* for execution
60	* @throws ExecutionException if the task encountered an exception
61	* while executing
62	*/
63	void invoke(Runnable task) throws ExecutionException, InterruptedException;
64
65	/**
66	* Executes a value-returning task and blocks until it returns a
67	* value or throws an exception.
68	*
69	* @param task the task to submit
70	* @return a Future representing pending completion of the task
71	* @throws RejectedExecutionException if task cannot be scheduled
72	* for execution
73	* @throws InterruptedException if interrupted while waiting for
74	* completion
75	* @throws ExecutionException if the task encountered an exception
76	* while executing
77	*/
78	<T> T invoke(Callable<T> task) throws ExecutionException, InterruptedException;
79
80
81	/**
82	* Submits a privileged action for execution under the current
83	* access control context and returns a Future representing the
84	* pending result object of that action.
85	*
86	* @param action the action to submit
87	* @return a Future representing pending completion of the action
88	* @throws RejectedExecutionException if action cannot be scheduled
89	* for execution
90	*/
91	Future<Object> submit(PrivilegedAction action);
92
93	/**
94	* Submits a privileged exception action for execution under the current
95	* access control context and returns a Future representing the pending
96	* result object of that action.
97	*
98	* @param action the action to submit
99	* @return a Future representing pending completion of the action
100	* @throws RejectedExecutionException if action cannot be scheduled
101	* for execution
102	*/
103	Future<Object> submit(PrivilegedExceptionAction action);
104
105
106	/**
107	* Initiates an orderly shutdown in which previously submitted
108	* tasks are executed, but no new tasks will be
109	* accepted. Invocation has no additional effect if already shut
110	* down.
111	*
112	*/
113	void shutdown();
114
115	/**
116	* Attempts to stop all actively executing tasks, halts the
117	* processing of waiting tasks, and returns a list of the tasks that were
118	* awaiting execution.
119	*
120	* <p>There are no guarantees beyond best-effort attempts to stop
121	* processing actively executing tasks. For example, typical
122	* implementations will cancel via {@link Thread#interrupt}, so if any
123	* tasks mask or fail to respond to interrupts, they may never terminate.
124	*
125	* @return list of tasks that never commenced execution
126	*/
127	List shutdownNow();
128
129	/**
130	* Returns <tt>true</tt> if this executor has been shut down.
131	*
132	* @return <tt>true</tt> if this executor has been shut down
133	*/
134	boolean isShutdown();
135
136	/**
137	* Returns <tt>true</tt> if all tasks have completed following shut down.
138	* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
139	* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
140	*
141	* @return <tt>true</tt> if all tasks have completed following shut down
142	*/
143	boolean isTerminated();
144
145	/**
146	* Blocks until all tasks have completed execution after a shutdown
147	* request, or the timeout occurs, or the current thread is
148	* interrupted, whichever happens first.
149	*
150	* @param timeout the maximum time to wait
151	* @param unit the time unit of the timeout argument
152	* @return <tt>true</tt> if this executor terminated and <tt>false</tt>
153	* if the timeout elapsed before termination
154	* @throws InterruptedException if interrupted while waiting
155	*/
156	boolean awaitTermination(long timeout, TimeUnit unit)
157	throws InterruptedException;
158
159	}