ThreadPool


1   /*
2    * Copyright 1999,2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.catalina.cluster.tcp;
18  import java.util.List  ;
19  import java.util.LinkedList  ;
20  
21  /**
22   * @author not attributable
23   * @version 1.0
24   */
25  
26  public class ThreadPool
27  {
28      /**
29       * A very simple thread pool class.  The pool size is set at
30       * construction time and remains fixed.  Threads are cycled
31       * through a FIFO idle queue.
32       */
33  
34      List   idle = new LinkedList  ();
35      Object   mutex = new Object  ();
36      Object   interestOpsMutex = null;
37  
38      ThreadPool (int poolSize, Class   threadClass, Object   interestOpsMutex) throws Exception   {
39          // fill up the pool with worker threads
40          this.interestOpsMutex = interestOpsMutex;
41          for (int i = 0; i < poolSize; i++) {
42              WorkerThread thread = (WorkerThread)threadClass.newInstance();
43              thread.setPool(this);
44  
45              // set thread name for debugging, start it
46              thread.setName (threadClass.getName()+"[" + (i + 1)+"]");
47              thread.setDaemon(true);
48              thread.setPriority(Thread.MAX_PRIORITY);
49              thread.start();
50  
51              idle.add (thread);
52          }
53      }
54  
55      /**
56       * Find an idle worker thread, if any.  Could return null.
57       */
58      WorkerThread getWorker()
59      {
60          WorkerThread worker = null;
61  
62          
63          synchronized (mutex) {
64              while ( worker == null ) {
65                  if (idle.size() > 0) {
66                      try {
67                          worker = (WorkerThread) idle.remove(0);
68                      } catch (java.util.NoSuchElementException   x) {
69                          //this means that there are no available workers
70                          worker = null;
71                      }
72                  } else {
73                      try { mutex.wait(); } catch ( java.lang.InterruptedException   x ) {}
74                  }
75              }
76          }
77  
78          return (worker);
79      }
80  
81      /**
82       * Called by the worker thread to return itself to the
83       * idle pool.
84       */
85      void returnWorker (WorkerThread worker)
86      {
87          synchronized (mutex) {
88              idle.add (worker);
89              mutex.notify();
90          }
91      }
92      public Object   getInterestOpsMutex() {
93          return interestOpsMutex;
94      }
95  }
96
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags