LifeCycleThread


1   // ========================================================================
2   // $Id: LifeCycleThread.java,v 1.9 2005/08/13 00:01:28 gregwilkins Exp $
3   // Copyright 1999-2004 Mort Bay Consulting Pty. Ltd.
4   // ------------------------------------------------------------------------
5   // Licensed under the Apache License, Version 2.0 (the "License");
6   // you may not use this file except in compliance with the License.
7   // You may obtain a copy of the License at 
8   // http://www.apache.org/licenses/LICENSE-2.0
9   // Unless required by applicable law or agreed to in writing, software
10  // distributed under the License is distributed on an "AS IS" BASIS,
11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  // See the License for the specific language governing permissions and
13  // limitations under the License.
14  // ========================================================================
15  
16  package org.mortbay.util;
17  
18  import java.io.InterruptedIOException  ;
19  
20  import org.apache.commons.logging.Log;
21  import org.mortbay.log.LogFactory;
22  
23  /* ------------------------------------------------------------ */
24  /** Base Thread class implementing LifeCycle.
25   *
26   * @version $Revision: 1.9 $
27   * @author Greg Wilkins (gregw)
28   */
29  public abstract class LifeCycleThread implements LifeCycle, Runnable  
30  {
31      private static Log log = LogFactory.getLog(LifeCycleThread.class);
32  
33      private boolean _running;
34      private boolean _daemon ;
35      private Thread   _thread;
36      
37      /* ------------------------------------------------------------ */
38      public boolean isDaemon()
39      {
40          return _daemon;
41      }
42      
43      /* ------------------------------------------------------------ */
44      public void setDaemon(boolean d)
45      {
46          _daemon = d;
47      }
48      
49      /* ------------------------------------------------------------ */
50      public Thread   getThread()
51      {
52          return _thread;
53      }
54      
55      /* ------------------------------------------------------------ */
56      public boolean isStarted()
57      {
58          return _running;
59      }
60  
61      /* ------------------------------------------------------------ */
62      public synchronized void start()
63          throws Exception  
64      {
65          if (_running)
66          {
67              log.debug("Already started");
68              return;
69          }
70          _running=true;
71          if (_thread==null)
72          {
73              _thread=new Thread  (this);
74              _thread.setDaemon(_daemon);
75          }
76          _thread.start();
77      }
78      
79      /* ------------------------------------------------------------ */
80      /** 
81       */
82      public synchronized void stop()
83          throws InterruptedException  
84      {
85          _running=false;
86          if (_thread!=null)
87          {
88              _thread.interrupt();
89              _thread.join();
90          }
91      }
92      
93  
94      /* ------------------------------------------------------------ */
95      /** 
96       */
97      public final void run()
98      {
99          try
100         {
101             while(_running)
102             {
103                 try
104                 {
105                     loop();
106                 }
107                 catch(InterruptedException   e)
108                 {
109                     LogSupport.ignore(log,e);
110                 }
111                 catch(InterruptedIOException   e)
112                 {
113                     LogSupport.ignore(log,e);
114                 }
115                 catch(Exception   e)
116                 {
117                     if (exception(e))
118                         break;
119                 } 
120                 catch(Error   e)
121                 {
122                     if (error(e))
123                         break;
124                 }   
125             }
126         }
127         finally
128         {
129             _running=false;
130         }
131     }
132 
133     /* ------------------------------------------------------------ */
134     /** Handle exception from loop.
135      * @param e The exception
136      * @return True of the loop should continue;
137      */
138     public boolean exception(Exception   e)
139     {
140         log.warn(LogSupport.EXCEPTION,e);
141         return true;
142     }
143     
144     /* ------------------------------------------------------------ */
145     /** Handle error from loop.
146      * @param e The exception
147      * @return True of the loop should continue;
148      */
149     public boolean error(Error   e)
150     {
151         log.warn(LogSupport.EXCEPTION,e);
152         return true;
153     }
154     
155     /* ------------------------------------------------------------ */
156     /** 
157      * @exception InterruptedException 
158      * @exception InterruptedIOException 
159      */
160     public abstract void loop()
161     throws InterruptedException  ,
162            InterruptedIOException  ,
163            Exception  ;
164     
165 }
166
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