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31  package org.apache.commons.httpclient.util;
32  
33  /**
34   * <p>
35   * Executes a task with a specified timeout.
36   * </p>
37   * @author Ortwin Glueck
38   * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
39   * @version $Revision: 480424 $
40   * @since 2.0
41   */
42  public final class TimeoutController {
43  
44      /**
45       * Do not instantiate objects of this class. Methods are static.
46       */
47      private TimeoutController() {
48      }
49  
50      /**
51       * Executes <code>task</code>. Waits for <code>timeout</code>
52       * milliseconds for the task to end and returns. If the task does not return
53       * in time, the thread is interrupted and an Exception is thrown.
54       * The caller should override the Thread.interrupt() method to something that
55       * quickly makes the thread die or use Thread.isInterrupted().
56       * @param task The thread to execute
57       * @param timeout The timeout in milliseconds. 0 means to wait forever.
58       * @throws TimeoutException if the timeout passes and the thread does not return.
59       */
60      public static void execute(Thread task, long timeout) throws TimeoutException {
61          task.start();
62          try {
63              task.join(timeout);
64          } catch (InterruptedException e) {
65              
66          }
67          if (task.isAlive()) {
68              task.interrupt();
69              throw new TimeoutException();
70          }
71      }
72  
73      /**
74       * Executes <code>task</code> in a new deamon Thread and waits for the timeout.
75       * @param task The task to execute
76       * @param timeout The timeout in milliseconds. 0 means to wait forever.
77       * @throws TimeoutException if the timeout passes and the thread does not return.
78       */
79      public static void execute(Runnable task, long timeout) throws TimeoutException {
80          Thread t = new Thread(task, "Timeout guard");
81          t.setDaemon(true);
82          execute(t, timeout);
83      }
84  
85      /**
86       * Signals that the task timed out.
87       */
88      public static class TimeoutException extends Exception {
89          /** Create an instance */
90          public TimeoutException() {
91          }
92      }
93  }