ThreadPool


1   package org.apache.axis2.util.threadpool;
2   
3   import org.apache.axis2.engine.AxisFault;
4   import org.apache.commons.logging.Log;
5   import org.apache.commons.logging.LogFactory;
6   
7   import java.util.ArrayList  ;
8   import java.util.Iterator  ;
9   import java.util.List  ;
10  
11  /**
12   * This the thread pool for axis2. This class will be used a singleton
13   * across axis2 engine. <code>ThreadPool</code> is accepts <code>AxisWorkers</code> which has
14   * doWork method on them and execute this method, using one of the threads
15   * in the thread pool.
16   */
17  
18  public class ThreadPool {
19  
20      protected static Log log = LogFactory.getLog(ThreadPool.class.getName());
21  
22      private static int MAX_THREAD_COUNT = 10;
23      protected static long SLEEP_INTERVAL = 1000;
24      private static List   threads;
25      private static List   tasks;
26      private static boolean shoutDown;
27  
28      public ThreadPool() {
29          threads = new ArrayList  ();
30          tasks = new ArrayList  ();
31  
32          for (int i = 0; i < MAX_THREAD_COUNT; i++) {
33              ThreadWorker threadWorker = new ThreadWorker();
34              threadWorker.setPool(this);
35              threads.add(threadWorker);
36              threadWorker.start();
37          }
38  
39      }
40  
41      public void addWorker(AxisWorker worker) throws AxisFault {
42          if (shoutDown)
43              throw new AxisFault("Thread Pool is Shutting Down");
44          tasks.add(worker);
45      }
46  
47      public synchronized AxisWorker getWorker() {
48          if (!tasks.isEmpty()) {
49              AxisWorker worker = (AxisWorker) tasks.get(0);
50              tasks.remove(worker);
51              return worker;
52          } else
53              return null;
54      }
55  
56      /**
57       * This is the recommended shutdown method for the thread pool
58       * This will wait till all the workers that are already handed over to the
59       * thread pool get executed.
60       *
61       * @throws AxisFault
62       */
63      public void safeShutDown() throws AxisFault {
64          synchronized (this) {
65              shoutDown = true;
66          }
67          while (!tasks.isEmpty()) {
68              try {
69                  Thread.sleep(SLEEP_INTERVAL);
70              } catch (InterruptedException   e) {
71                  throw new AxisFault("Error while safeShutDown", e);
72              }
73          }
74          forceShutDown();
75  
76      }
77  
78      /**
79       * A forceful shutdown mechanism for thread pool.
80       */
81      public void forceShutDown() {
82          if (log.isDebugEnabled())
83              log.debug("forceShutDown called. Thread workers will be stopped");
84          Iterator   ite = threads.iterator();
85          while (ite.hasNext()) {
86              ThreadWorker worker = (ThreadWorker) ite.next();
87              worker.setStop(true);
88          }
89      }
90  }
91
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