187 lines
8.3 KiB
Java
187 lines
8.3 KiB
Java
/*
|
|
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
*
|
|
* This code is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 only, as
|
|
* published by the Free Software Foundation. Oracle designates this
|
|
* particular file as subject to the "Classpath" exception as provided
|
|
* by Oracle in the LICENSE file that accompanied this code.
|
|
*
|
|
* This code is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
* version 2 for more details (a copy is included in the LICENSE file that
|
|
* accompanied this code).
|
|
*
|
|
* You should have received a copy of the GNU General Public License version
|
|
* 2 along with this work; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*
|
|
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
|
|
* or visit www.oracle.com if you need additional information or have any
|
|
* questions.
|
|
*/
|
|
|
|
/*
|
|
* This file is available under and governed by the GNU General Public
|
|
* License version 2 only, as published by the Free Software Foundation.
|
|
* However, the following notice accompanied the original version of this
|
|
* file:
|
|
*
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166
|
|
* Expert Group and released to the public domain, as explained at
|
|
* http://creativecommons.org/publicdomain/zero/1.0/
|
|
*/
|
|
|
|
package java.util.concurrent;
|
|
|
|
/**
|
|
* An {@link ExecutorService} that can schedule commands to run after a given
|
|
* delay, or to execute periodically.
|
|
*
|
|
* <p>The {@code schedule} methods create tasks with various delays
|
|
* and return a task object that can be used to cancel or check
|
|
* execution. The {@code scheduleAtFixedRate} and
|
|
* {@code scheduleWithFixedDelay} methods create and execute tasks
|
|
* that run periodically until cancelled.
|
|
*
|
|
* <p>Commands submitted using the {@link Executor#execute(Runnable)}
|
|
* and {@link ExecutorService} {@code submit} methods are scheduled
|
|
* with a requested delay of zero. Zero and negative delays (but not
|
|
* periods) are also allowed in {@code schedule} methods, and are
|
|
* treated as requests for immediate execution.
|
|
*
|
|
* <p>All {@code schedule} methods accept <em>relative</em> delays and
|
|
* periods as arguments, not absolute times or dates. It is a simple
|
|
* matter to transform an absolute time represented as a {@link
|
|
* java.util.Date} to the required form. For example, to schedule at
|
|
* a certain future {@code date}, you can use: {@code schedule(task,
|
|
* date.getTime() - System.currentTimeMillis(),
|
|
* TimeUnit.MILLISECONDS)}. Beware however that expiration of a
|
|
* relative delay need not coincide with the current {@code Date} at
|
|
* which the task is enabled due to network time synchronization
|
|
* protocols, clock drift, or other factors.
|
|
*
|
|
* <p>The {@link Executors} class provides convenient factory methods for
|
|
* the ScheduledExecutorService implementations provided in this package.
|
|
*
|
|
* <h3>Usage Example</h3>
|
|
*
|
|
* Here is a class with a method that sets up a ScheduledExecutorService
|
|
* to beep every ten seconds for an hour:
|
|
*
|
|
* <pre> {@code
|
|
* import static java.util.concurrent.TimeUnit.*;
|
|
* class BeeperControl {
|
|
* private final ScheduledExecutorService scheduler =
|
|
* Executors.newScheduledThreadPool(1);
|
|
*
|
|
* public void beepForAnHour() {
|
|
* final Runnable beeper = new Runnable() {
|
|
* public void run() { System.out.println("beep"); }
|
|
* };
|
|
* final ScheduledFuture<?> beeperHandle =
|
|
* scheduler.scheduleAtFixedRate(beeper, 10, 10, SECONDS);
|
|
* scheduler.schedule(new Runnable() {
|
|
* public void run() { beeperHandle.cancel(true); }
|
|
* }, 60 * 60, SECONDS);
|
|
* }
|
|
* }}</pre>
|
|
*
|
|
* @since 1.5
|
|
* @author Doug Lea
|
|
*/
|
|
public interface ScheduledExecutorService extends ExecutorService {
|
|
|
|
/**
|
|
* Creates and executes a one-shot action that becomes enabled
|
|
* after the given delay.
|
|
*
|
|
* @param command the task to execute
|
|
* @param delay the time from now to delay execution
|
|
* @param unit the time unit of the delay parameter
|
|
* @return a ScheduledFuture representing pending completion of
|
|
* the task and whose {@code get()} method will return
|
|
* {@code null} upon completion
|
|
* @throws RejectedExecutionException if the task cannot be
|
|
* scheduled for execution
|
|
* @throws NullPointerException if command is null
|
|
*/
|
|
public ScheduledFuture<?> schedule(Runnable command,
|
|
long delay, TimeUnit unit);
|
|
|
|
/**
|
|
* Creates and executes a ScheduledFuture that becomes enabled after the
|
|
* given delay.
|
|
*
|
|
* @param callable the function to execute
|
|
* @param delay the time from now to delay execution
|
|
* @param unit the time unit of the delay parameter
|
|
* @param <V> the type of the callable's result
|
|
* @return a ScheduledFuture that can be used to extract result or cancel
|
|
* @throws RejectedExecutionException if the task cannot be
|
|
* scheduled for execution
|
|
* @throws NullPointerException if callable is null
|
|
*/
|
|
public <V> ScheduledFuture<V> schedule(Callable<V> callable,
|
|
long delay, TimeUnit unit);
|
|
|
|
/**
|
|
* Creates and executes a periodic action that becomes enabled first
|
|
* after the given initial delay, and subsequently with the given
|
|
* period; that is executions will commence after
|
|
* {@code initialDelay} then {@code initialDelay+period}, then
|
|
* {@code initialDelay + 2 * period}, and so on.
|
|
* If any execution of the task
|
|
* encounters an exception, subsequent executions are suppressed.
|
|
* Otherwise, the task will only terminate via cancellation or
|
|
* termination of the executor. If any execution of this task
|
|
* takes longer than its period, then subsequent executions
|
|
* may start late, but will not concurrently execute.
|
|
*
|
|
* @param command the task to execute
|
|
* @param initialDelay the time to delay first execution
|
|
* @param period the period between successive executions
|
|
* @param unit the time unit of the initialDelay and period parameters
|
|
* @return a ScheduledFuture representing pending completion of
|
|
* the task, and whose {@code get()} method will throw an
|
|
* exception upon cancellation
|
|
* @throws RejectedExecutionException if the task cannot be
|
|
* scheduled for execution
|
|
* @throws NullPointerException if command is null
|
|
* @throws IllegalArgumentException if period less than or equal to zero
|
|
*/
|
|
public ScheduledFuture<?> scheduleAtFixedRate(Runnable command,
|
|
long initialDelay,
|
|
long period,
|
|
TimeUnit unit);
|
|
|
|
/**
|
|
* Creates and executes a periodic action that becomes enabled first
|
|
* after the given initial delay, and subsequently with the
|
|
* given delay between the termination of one execution and the
|
|
* commencement of the next. If any execution of the task
|
|
* encounters an exception, subsequent executions are suppressed.
|
|
* Otherwise, the task will only terminate via cancellation or
|
|
* termination of the executor.
|
|
*
|
|
* @param command the task to execute
|
|
* @param initialDelay the time to delay first execution
|
|
* @param delay the delay between the termination of one
|
|
* execution and the commencement of the next
|
|
* @param unit the time unit of the initialDelay and delay parameters
|
|
* @return a ScheduledFuture representing pending completion of
|
|
* the task, and whose {@code get()} method will throw an
|
|
* exception upon cancellation
|
|
* @throws RejectedExecutionException if the task cannot be
|
|
* scheduled for execution
|
|
* @throws NullPointerException if command is null
|
|
* @throws IllegalArgumentException if delay less than or equal to zero
|
|
*/
|
|
public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command,
|
|
long initialDelay,
|
|
long delay,
|
|
TimeUnit unit);
|
|
|
|
}
|