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;

/**
 * An executor 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 <tt>Executors</tt> class provides factory methods for the
 * executor services provided in <tt>java.util.concurrent</tt>.
 *
 * @since 1.5
 * @see Executors
 *
 * @spec JSR-166
 * @revised $Date: 2003/06/24 14:34:48 $
 * @editor $Author: dl $
 * @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.
     *
     */
    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:	1.6
Committed:	Sun Aug 24 14:47:31 2003 UTC (20 years, 9 months ago) by dl
Branch:	MAIN
Changes since 1.5:	+5 -3 lines
Log Message:	Javadoc clarifications
#	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
11	/**
12	* An executor that provides methods to manage termination. An
13	* <tt>ExecutorService</tt> can be shut down, which will cause it to
14	* stop accepting new tasks. After being shut down, the executor will
15	* eventually terminate, at which point no tasks are actively
16	* executing, no tasks are awaiting execution, and no new tasks can be
17	* submitted.
18	*
19	* <p>The <tt>Executors</tt> class provides factory methods for the
20	* executor services provided in <tt>java.util.concurrent</tt>.
21	*
22	* @since 1.5
23	* @see Executors
24	*
25	* @spec JSR-166
26	* @revised $Date: 2003/06/24 14:34:48 $
27	* @editor $Author: dl $
28	* @author Doug Lea
29	*/
30	public interface ExecutorService extends Executor {
31
32	/**
33	* Initiates an orderly shutdown in which previously submitted
34	* tasks are executed, but no new tasks will be
35	* accepted. Invocation has no additional effect if already shut
36	* down.
37	*
38	*/
39	void shutdown();
40
41	/**
42	* Attempts to stop all actively executing tasks, halts the
43	* processing of waiting tasks, and returns a list of the tasks that were
44	* awaiting execution.
45	*
46	* <p>There are no guarantees beyond best-effort attempts to stop
47	* processing actively executing tasks. For example, typical
48	* implementations will cancel via {@link Thread#interrupt}, so if any
49	* tasks mask or fail to respond to interrupts, they may never terminate.
50	*
51	* @return list of tasks that never commenced execution
52	*/
53	List shutdownNow();
54
55	/**
56	* Returns <tt>true</tt> if this executor has been shut down.
57	*
58	* @return <tt>true</tt> if this executor has been shut down
59	*/
60	boolean isShutdown();
61
62	/**
63	* Returns <tt>true</tt> if all tasks have completed following shut down.
64	* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless
65	* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first.
66	*
67	* @return <tt>true</tt> if all tasks have completed following shut down
68	*/
69	boolean isTerminated();
70
71	/**
72	* Blocks until all tasks have completed execution after a shutdown
73	* request, or the timeout occurs, or the current thread is
74	* interrupted, whichever happens first.
75	*
76	* @param timeout the maximum time to wait
77	* @param unit the time unit of the timeout argument
78	* @return <tt>true</tt> if this executor terminated and <tt>false</tt>
79	* if the timeout elapsed before termination
80	* @throws InterruptedException if interrupted while waiting
81	*/
82	boolean awaitTermination(long timeout, TimeUnit unit)
83	throws InterruptedException;
84
85	}