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).
#	User	Rev	Content
1	dl	1.1	/*
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	tim	1.8	import java.security.PrivilegedAction;
11			import java.security.PrivilegedExceptionAction;
12	dl	1.1
13			/**
14	dl	1.7	* 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	dl	1.1	* executing, no tasks are awaiting execution, and no new tasks can be
19			* submitted.
20			*
21	dl	1.7	* <p>The {@link Executors} class provides factory methods for the
22			* executor services provided in this package.
23	dl	1.1	*
24			* @since 1.5
25	dl	1.5	* @author Doug Lea
26	dl	1.1	*/
27			public interface ExecutorService extends Executor {
28	tim	1.8
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	dl	1.1
106			/**
107	dl	1.6	* 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	dl	1.1	*
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	dl	1.3
159	dl	1.1	}