LimitedDurationDispatcher


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3    * Institute of Technology.  All rights reserved.
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34  package org.dspace.checker;
35  
36  import java.util.Date  ;
37  
38  /**
39   * <p>
40   * A delegating dispatcher that puts a time limit on the operation of another
41   * dispatcher.
42   * </p>
43   * 
44   * <p>
45   * Unit testing this class would be possible by abstracting the system time into
46   * an abstract clock. We decided this was not worth the candle.
47   * </p>
48   * 
49   * @author Jim Downing
50   * @author Grace Carpenter
51   * @author Nathan Sarr
52   * 
53   */
54  public class LimitedDurationDispatcher implements BitstreamDispatcher
55  {
56      /**
57       * The delegate dispatcher that will actually dispatch the jobs.
58       */
59      private BitstreamDispatcher delegate;
60  
61      /**
62       * Milliseconds since epoch after which this dispatcher will stop returning
63       * values.
64       */
65      private long end;
66  
67      /**
68       * Blanked off constructor - do not use.
69       */
70      private LimitedDurationDispatcher()
71      {
72          end = 0L;
73          delegate = null;
74      }
75  
76      /**
77       * Main constructor.
78       * 
79       * @param dispatcher
80       *            Delegate dispatcher that will do the heavy lifting of the
81       *            dispatching work.
82       * @param endTime
83       *            when this dispatcher will stop returning valid bitstream ids.
84       */
85      public LimitedDurationDispatcher(BitstreamDispatcher dispatcher,
86              Date   endTime)
87      {
88          delegate = dispatcher;
89          end = endTime.getTime();
90      }
91  
92      /**
93       * @see org.dspace.checker.BitstreamDispatcher#next()
94       */
95      public int next()
96      {
97          return (System.currentTimeMillis() > end) ? SENTINEL : delegate.next();
98      }
99  }
100
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