1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/emul/compact/src/main/java/java/util/concurrent/Executor.java Sat Sep 07 13:51:24 2013 +0200
1.3 @@ -0,0 +1,141 @@
1.4 +/*
1.5 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.6 + *
1.7 + * This code is free software; you can redistribute it and/or modify it
1.8 + * under the terms of the GNU General Public License version 2 only, as
1.9 + * published by the Free Software Foundation. Oracle designates this
1.10 + * particular file as subject to the "Classpath" exception as provided
1.11 + * by Oracle in the LICENSE file that accompanied this code.
1.12 + *
1.13 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.14 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.15 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.16 + * version 2 for more details (a copy is included in the LICENSE file that
1.17 + * accompanied this code).
1.18 + *
1.19 + * You should have received a copy of the GNU General Public License version
1.20 + * 2 along with this work; if not, write to the Free Software Foundation,
1.21 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.22 + *
1.23 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.24 + * or visit www.oracle.com if you need additional information or have any
1.25 + * questions.
1.26 + */
1.27 +
1.28 +/*
1.29 + * This file is available under and governed by the GNU General Public
1.30 + * License version 2 only, as published by the Free Software Foundation.
1.31 + * However, the following notice accompanied the original version of this
1.32 + * file:
1.33 + *
1.34 + * Written by Doug Lea with assistance from members of JCP JSR-166
1.35 + * Expert Group and released to the public domain, as explained at
1.36 + * http://creativecommons.org/publicdomain/zero/1.0/
1.37 + */
1.38 +
1.39 +package java.util.concurrent;
1.40 +
1.41 +/**
1.42 + * An object that executes submitted {@link Runnable} tasks. This
1.43 + * interface provides a way of decoupling task submission from the
1.44 + * mechanics of how each task will be run, including details of thread
1.45 + * use, scheduling, etc. An <tt>Executor</tt> is normally used
1.46 + * instead of explicitly creating threads. For example, rather than
1.47 + * invoking <tt>new Thread(new(RunnableTask())).start()</tt> for each
1.48 + * of a set of tasks, you might use:
1.49 + *
1.50 + * <pre>
1.51 + * Executor executor = <em>anExecutor</em>;
1.52 + * executor.execute(new RunnableTask1());
1.53 + * executor.execute(new RunnableTask2());
1.54 + * ...
1.55 + * </pre>
1.56 + *
1.57 + * However, the <tt>Executor</tt> interface does not strictly
1.58 + * require that execution be asynchronous. In the simplest case, an
1.59 + * executor can run the submitted task immediately in the caller's
1.60 + * thread:
1.61 + *
1.62 + * <pre>
1.63 + * class DirectExecutor implements Executor {
1.64 + * public void execute(Runnable r) {
1.65 + * r.run();
1.66 + * }
1.67 + * }</pre>
1.68 + *
1.69 + * More typically, tasks are executed in some thread other
1.70 + * than the caller's thread. The executor below spawns a new thread
1.71 + * for each task.
1.72 + *
1.73 + * <pre>
1.74 + * class ThreadPerTaskExecutor implements Executor {
1.75 + * public void execute(Runnable r) {
1.76 + * new Thread(r).start();
1.77 + * }
1.78 + * }</pre>
1.79 + *
1.80 + * Many <tt>Executor</tt> implementations impose some sort of
1.81 + * limitation on how and when tasks are scheduled. The executor below
1.82 + * serializes the submission of tasks to a second executor,
1.83 + * illustrating a composite executor.
1.84 + *
1.85 + * <pre> {@code
1.86 + * class SerialExecutor implements Executor {
1.87 + * final Queue<Runnable> tasks = new ArrayDeque<Runnable>();
1.88 + * final Executor executor;
1.89 + * Runnable active;
1.90 + *
1.91 + * SerialExecutor(Executor executor) {
1.92 + * this.executor = executor;
1.93 + * }
1.94 + *
1.95 + * public synchronized void execute(final Runnable r) {
1.96 + * tasks.offer(new Runnable() {
1.97 + * public void run() {
1.98 + * try {
1.99 + * r.run();
1.100 + * } finally {
1.101 + * scheduleNext();
1.102 + * }
1.103 + * }
1.104 + * });
1.105 + * if (active == null) {
1.106 + * scheduleNext();
1.107 + * }
1.108 + * }
1.109 + *
1.110 + * protected synchronized void scheduleNext() {
1.111 + * if ((active = tasks.poll()) != null) {
1.112 + * executor.execute(active);
1.113 + * }
1.114 + * }
1.115 + * }}</pre>
1.116 + *
1.117 + * The <tt>Executor</tt> implementations provided in this package
1.118 + * implement {@link ExecutorService}, which is a more extensive
1.119 + * interface. The {@link ThreadPoolExecutor} class provides an
1.120 + * extensible thread pool implementation. The {@link Executors} class
1.121 + * provides convenient factory methods for these Executors.
1.122 + *
1.123 + * <p>Memory consistency effects: Actions in a thread prior to
1.124 + * submitting a {@code Runnable} object to an {@code Executor}
1.125 + * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
1.126 + * its execution begins, perhaps in another thread.
1.127 + *
1.128 + * @since 1.5
1.129 + * @author Doug Lea
1.130 + */
1.131 +public interface Executor {
1.132 +
1.133 + /**
1.134 + * Executes the given command at some time in the future. The command
1.135 + * may execute in a new thread, in a pooled thread, or in the calling
1.136 + * thread, at the discretion of the <tt>Executor</tt> implementation.
1.137 + *
1.138 + * @param command the runnable task
1.139 + * @throws RejectedExecutionException if this task cannot be
1.140 + * accepted for execution.
1.141 + * @throws NullPointerException if command is null
1.142 + */
1.143 + void execute(Runnable command);
1.144 +}