ParallelJob


1   package org.oddjob.jobs.structural;
2   
3   import java.util.Enumeration  ;
4   import java.util.Vector  ;
5   
6   import org.oddjob.Stoppable;
7   import org.oddjob.framework.StructuralJob;
8   
9   /**
10   * @oddjob.description
11   * 
12   * A job which contains many child jobs and executes 
13   * them all in parallel each on a separate thread.
14   * <p>
15   * The return state for this job depends on the return
16   * states of all the children - Complete if all the 
17   * children complete, exception if there are any exceptions
18   * in the chilren, 
19   * or not complete if any of the children fail to complete. 
20   * 
21   * @oddjob.example
22   * 
23   * <pre>
24   * &lt;parallel&gt;
25   *   &lt;echo message="This runs in parallel,"&gt;/>
26   *   &lt;echo message="with this."&gt;/>
27   * &lt;/parallel&gt;
28   * </pre>
29   * 
30   * @author Rob Gordon
31   */
32  
33  public class ParallelJob extends StructuralJob
34              implements Stoppable {
35  
36      /**
37       * Called by framework after parsing. 
38       *
39       */
40      public void init() {
41          childHelper.initialise();
42      }
43          
44      /**
45       * Add a child job.
46       * 
47       * @oddjob.element <i>Any</i>
48       * @oddjob.description The child jobs.
49       * @oddjob.required No, but pointless if missing.
50       * 
51       * @param child A child
52       */
53      public void addComponent(Object   child) {
54          logger().debug("Adding child [" + child + "]");
55          childHelper.addChild(child);
56      }
57  
58      /*
59       *  (non-Javadoc)
60       * @see org.oddjob.jobs.AbstractJob#execute()
61       */
62      protected void execute() throws InterruptedException   {
63          Vector   jobThreads = new Vector  ();
64          Object  [] children = childHelper.getChildren();
65  
66          for (int i = 0; i < children.length; ++i) {
67              if (children[i] instanceof Runnable  ) {
68                  Thread   t = new Thread  ((Runnable  ) children[i]);
69                  jobThreads.add(t);
70                  t.start();
71              }
72          }
73          
74          for (Enumeration   elements = jobThreads.elements(); 
75                  elements.hasMoreElements() ;) {
76              Thread   t = (Thread  )elements.nextElement();
77              t.join();
78          }
79      }       
80  }
81
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