DELAY


1   // $Id: DELAY.java,v 1.5 2004/07/05 14:17:15 belaban Exp $
2   
3   package org.jgroups.protocols;
4   
5   import org.jgroups.Event;
6   import org.jgroups.stack.Protocol;
7   import org.jgroups.util.Util;
8   
9   import java.util.Properties  ;
10  
11  
12  /**
13   * Delays incoming/outgoing messages by a random number of milliseconds (range between 0 and n
14   * where n is determined by the user). Incoming messages can be delayed independently from
15   * outgoing messages (or not delayed at all).<p>
16   * This protocol should be inserted directly above the bottommost protocol (e.g. UDP).
17   */
18  
19  public class DELAY extends Protocol {
20      int in_delay=0, out_delay=0;
21  
22      /**
23       * All protocol names have to be unique !
24       */
25      public String   getName() {
26          return "DELAY";
27      }
28  
29  
30      public boolean setProperties(Properties   props) {
31          String   str;
32  
33          super.setProperties(props);
34  
35          str=props.getProperty("in_delay");
36          if(str != null) {
37              in_delay=Integer.parseInt(str);
38              props.remove("in_delay");
39          }
40  
41          str=props.getProperty("out_delay");
42          if(str != null) {
43              out_delay=Integer.parseInt(str);
44              props.remove("out_delay");
45          }
46  
47          if(props.size() > 0) {
48              System.err.println("DELAY.setProperties(): these properties are not recognized:");
49              props.list(System.out);
50              return false;
51          }
52          return true;
53      }
54  
55  
56      public void up(Event evt) {
57          int delay=in_delay > 0 ? computeDelay(in_delay) : 0;
58  
59  
60          switch(evt.getType()) {
61              case Event.MSG:         // Only delay messages, not other events !
62  
63                  if(log.isInfoEnabled()) log.info("delaying incoming message for " + delay + " milliseconds");
64                  Util.sleep(delay);
65                  break;
66          }
67  
68          passUp(evt);            // Pass up to the layer above us
69      }
70  
71  
72      public void down(Event evt) {
73          int delay=out_delay > 0 ? computeDelay(out_delay) : 0;
74  
75          switch(evt.getType()) {
76  
77              case Event.MSG:         // Only delay messages, not other events !
78  
79                  if(log.isInfoEnabled()) log.info("delaying outgoing message for " + delay + " milliseconds");
80                  Util.sleep(delay);
81                  break;
82          }
83  
84          passDown(evt);          // Pass on to the layer below us
85      }
86  
87  
88      /**
89       * Compute a random number between 0 and n
90       */
91      int computeDelay(int n) {
92          return (int)((Math.random() * 1000000) % n);
93      }
94  
95  
96  }
97
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags