DedicatedTaskRunner


1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one or more
4    * contributor license agreements.  See the NOTICE file distributed with
5    * this work for additional information regarding copyright ownership.
6    * The ASF licenses this file to You under the Apache License, Version 2.0
7    * (the "License"); you may not use this file except in compliance with
8    * the License.  You may obtain a copy of the License at
9    *
10   * http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.activemq.thread;
19  
20  
21  /**
22   *
23   * @version $Revision: 1.1 $
24   */
25  class DedicatedTaskRunner implements TaskRunner {
26  
27      private final Task task;
28      private final Thread   thread;
29      
30      private final Object   mutex = new Object  ();
31      private boolean threadTerminated;
32      private boolean pending;
33      private boolean shutdown;
34      
35      public DedicatedTaskRunner(Task task, String   name, int priority, boolean daemon) {
36          this.task = task;
37          thread = new Thread  (name) {
38              public void run() {
39                  runTask();
40              }
41          };
42          thread.setDaemon(daemon);
43          thread.setName(name);
44          thread.setPriority(priority);
45          thread.start();
46      }
47      
48      /**
49       */
50      public void wakeup() throws InterruptedException   {
51          synchronized( mutex ) {
52              if( shutdown )
53                  return;
54              pending=true;            
55              mutex.notifyAll();
56          }
57      }
58  
59      /**
60       * shut down the task
61       * @param timeout 
62       * @throws InterruptedException 
63       */
64      public void shutdown(long timeout) throws InterruptedException  {
65          synchronized(mutex){
66              shutdown=true;
67              pending=true;
68              mutex.notifyAll();
69  
70              // Wait till the thread stops.
71              if(!threadTerminated){
72                  mutex.wait(timeout);
73              }
74          }
75      }      
76      
77      /**
78       * shut down the task
79       * @throws InterruptedException 
80       */
81      public void shutdown() throws InterruptedException  {
82          shutdown(0);
83      }
84      
85      private void runTask() {
86          
87          try {
88              while( true ) {
89               
90                  synchronized (mutex) {   
91                      pending=false;
92                      if( shutdown ) {
93                          return;
94                      }
95                  }
96                  
97                  if( !task.iterate() ) {
98                      // wait to be notified.
99                      synchronized (mutex) {
100                         while( !pending ) {
101                             mutex.wait();
102                         }
103                     }
104                 }
105                 
106             }
107             
108         } catch (InterruptedException   e) {
109             // Someone really wants this thread to die off.
110             Thread.currentThread().interrupt();
111         } finally {
112             // Make sure we notify any waiting threads that thread 
113             // has terminated.
114             synchronized (mutex) {
115                 threadTerminated=true;
116                 mutex.notifyAll();
117             }            
118         }
119     }
120 }
121
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