1/*
2 * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25package sun.jvm.hotspot.utilities;
26
27/** This class abstracts the notion of a worker thread which is fed
28    tasks in the form of Runnables. */
29
30public class WorkerThread {
31  private volatile boolean done = false;
32  private MessageQueueBackend mqb;
33  private MessageQueue mq;
34
35  public WorkerThread() {
36    mqb = new MessageQueueBackend();
37    mq = mqb.getFirstQueue();
38
39    // Enable to terminate this worker during runnning by daemonize.
40    Thread mqthread = new Thread(new MainLoop());
41    mqthread.setDaemon(true);
42    mqthread.start();
43  }
44
45  /** Runs the given Runnable in the thread represented by this
46      WorkerThread object at an unspecified later time. */
47  public void invokeLater(Runnable runnable) {
48    mq.writeMessage(runnable);
49  }
50
51  /** Can be used to dispose of the internal worker thread. Note that
52      this method may return before the internal worker thread
53      terminates. */
54  public void shutdown() {
55    done = true;
56    mq.writeMessage(new Runnable() { public void run() {} });
57  }
58
59  class MainLoop implements Runnable {
60    private MessageQueue myMq;
61
62    public MainLoop() {
63      myMq = mqb.getSecondQueue();
64    }
65
66    public void run() {
67      while (!done) {
68        Runnable runnable = (Runnable) myMq.readMessage();
69        try {
70          runnable.run();
71        } catch (Exception e) {
72          e.printStackTrace();
73        }
74      }
75    }
76  }
77}
78