1 //
2 // ========================================================================
3 // Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.util.thread;
20
21 import java.util.Arrays;
22 import java.util.List;
23 import java.util.concurrent.CopyOnWriteArrayList;
24
25 import org.eclipse.jetty.util.component.LifeCycle;
26 import org.eclipse.jetty.util.log.Log;
27 import org.eclipse.jetty.util.log.Logger;
28
29
30 /* ------------------------------------------------------------ */
31 /**
32 * ShutdownThread is a shutdown hook thread implemented as
33 * singleton that maintains a list of lifecycle instances
34 * that are registered with it and provides ability to stop
35 * these lifecycles upon shutdown of the Java Virtual Machine
36 */
37 public class ShutdownThread extends Thread
38 {
39 private static final Logger LOG = Log.getLogger(ShutdownThread.class);
40 private static final ShutdownThread _thread = new ShutdownThread();
41
42 private boolean _hooked;
43 private final List<LifeCycle> _lifeCycles = new CopyOnWriteArrayList<LifeCycle>();
44
45 /* ------------------------------------------------------------ */
46 /**
47 * Default constructor for the singleton
48 *
49 * Registers the instance as shutdown hook with the Java Runtime
50 */
51 private ShutdownThread()
52 {
53 }
54
55 /* ------------------------------------------------------------ */
56 private synchronized void hook()
57 {
58 try
59 {
60 if (!_hooked)
61 Runtime.getRuntime().addShutdownHook(this);
62 _hooked=true;
63 }
64 catch(Exception e)
65 {
66 LOG.ignore(e);
67 LOG.info("shutdown already commenced");
68 }
69 }
70
71 /* ------------------------------------------------------------ */
72 private synchronized void unhook()
73 {
74 try
75 {
76 _hooked=false;
77 Runtime.getRuntime().removeShutdownHook(this);
78 }
79 catch(Exception e)
80 {
81 LOG.ignore(e);
82 LOG.info("shutdown already commenced");
83 }
84 }
85
86 /* ------------------------------------------------------------ */
87 /**
88 * Returns the instance of the singleton
89 *
90 * @return the singleton instance of the {@link ShutdownThread}
91 */
92 public static ShutdownThread getInstance()
93 {
94 return _thread;
95 }
96
97 /* ------------------------------------------------------------ */
98 public static synchronized void register(LifeCycle... lifeCycles)
99 {
100 _thread._lifeCycles.addAll(Arrays.asList(lifeCycles));
101 if (_thread._lifeCycles.size()>0)
102 _thread.hook();
103 }
104
105 /* ------------------------------------------------------------ */
106 public static synchronized void register(int index, LifeCycle... lifeCycles)
107 {
108 _thread._lifeCycles.addAll(index,Arrays.asList(lifeCycles));
109 if (_thread._lifeCycles.size()>0)
110 _thread.hook();
111 }
112
113 /* ------------------------------------------------------------ */
114 public static synchronized void deregister(LifeCycle lifeCycle)
115 {
116 _thread._lifeCycles.remove(lifeCycle);
117 if (_thread._lifeCycles.size()==0)
118 _thread.unhook();
119 }
120
121 /* ------------------------------------------------------------ */
122 @Override
123 public void run()
124 {
125 for (LifeCycle lifeCycle : _thread._lifeCycles)
126 {
127 try
128 {
129 if (lifeCycle.isStarted())
130 {
131 lifeCycle.stop();
132 LOG.debug("Stopped {}",lifeCycle);
133 }
134 }
135 catch (Exception ex)
136 {
137 LOG.debug(ex);
138 }
139 }
140 }
141 }