--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/concurrent/Executor.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,141 @@
+/*
+ * 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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.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/licenses/publicdomain
+ */
+
+package java.util.concurrent;
+
+/**
+ * An object that executes submitted {@link Runnable} tasks. This
+ * interface provides a way of decoupling task submission from the
+ * mechanics of how each task will be run, including details of thread
+ * use, scheduling, etc.  An <tt>Executor</tt> is normally used
+ * instead of explicitly creating threads. For example, rather than
+ * invoking <tt>new Thread(new(RunnableTask())).start()</tt> for each
+ * of a set of tasks, you might use:
+ *
+ * <pre>
+ * Executor executor = <em>anExecutor</em>;
+ * executor.execute(new RunnableTask1());
+ * executor.execute(new RunnableTask2());
+ * ...
+ * </pre>
+ *
+ * However, the <tt>Executor</tt> interface does not strictly
+ * require that execution be asynchronous. In the simplest case, an
+ * executor can run the submitted task immediately in the caller's
+ * thread:
+ *
+ * <pre>
+ * class DirectExecutor implements Executor {
+ *     public void execute(Runnable r) {
+ *         r.run();
+ *     }
+ * }</pre>
+ *
+ * More typically, tasks are executed in some thread other
+ * than the caller's thread.  The executor below spawns a new thread
+ * for each task.
+ *
+ * <pre>
+ * class ThreadPerTaskExecutor implements Executor {
+ *     public void execute(Runnable r) {
+ *         new Thread(r).start();
+ *     }
+ * }</pre>
+ *
+ * Many <tt>Executor</tt> implementations impose some sort of
+ * limitation on how and when tasks are scheduled.  The executor below
+ * serializes the submission of tasks to a second executor,
+ * illustrating a composite executor.
+ *
+ * <pre>
+ * class SerialExecutor implements Executor {
+ *     final Queue&lt;Runnable&gt; tasks = new ArrayDeque&lt;Runnable&gt;();
+ *     final Executor executor;
+ *     Runnable active;
+ *
+ *     SerialExecutor(Executor executor) {
+ *         this.executor = executor;
+ *     }
+ *
+ *     public synchronized void execute(final Runnable r) {
+ *         tasks.offer(new Runnable() {
+ *             public void run() {
+ *                 try {
+ *                     r.run();
+ *                 } finally {
+ *                     scheduleNext();
+ *                 }
+ *             }
+ *         });
+ *         if (active == null) {
+ *             scheduleNext();
+ *         }
+ *     }
+ *
+ *     protected synchronized void scheduleNext() {
+ *         if ((active = tasks.poll()) != null) {
+ *             executor.execute(active);
+ *         }
+ *     }
+ * }</pre>
+ *
+ * The <tt>Executor</tt> implementations provided in this package
+ * implement {@link ExecutorService}, which is a more extensive
+ * interface.  The {@link ThreadPoolExecutor} class provides an
+ * extensible thread pool implementation. The {@link Executors} class
+ * provides convenient factory methods for these Executors.
+ *
+ * <p>Memory consistency effects: Actions in a thread prior to
+ * submitting a {@code Runnable} object to an {@code Executor}
+ * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
+ * its execution begins, perhaps in another thread.
+ *
+ * @since 1.5
+ * @author Doug Lea
+ */
+public interface Executor {
+
+    /**
+     * Executes the given command at some time in the future.  The command
+     * may execute in a new thread, in a pooled thread, or in the calling
+     * thread, at the discretion of the <tt>Executor</tt> implementation.
+     *
+     * @param command the runnable task
+     * @throws RejectedExecutionException if this task cannot be
+     * accepted for execution.
+     * @throws NullPointerException if command is null
+     */
+    void execute(Runnable command);
+}