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Java > Open Source Codes > org > jgroups > protocols > FLOWCONTROL


1 package org.jgroups.protocols;
2
3 import org.jgroups.Address;
4 import org.jgroups.Event;
5 import org.jgroups.Message;
6 import org.jgroups.stack.Protocol;
7
8 import java.util.Vector JavaDoc;
9
10
11
12
13 /**
14  * Title: Flow control layer
15  * Description: This layer limits the number of sent messages without a receive of an own message to MAXSENTMSGS,
16  * just put this layer above GMS and you will get a more
17  * Copyright: Copyright (c) 2000
18  * Company: Computer Network Laboratory
19  * @author Gianluca Collot
20  * @version 1.0
21  */
22 public class FLOWCONTROL extends Protocol {
23
24   final Vector JavaDoc queuedMsgs = new Vector JavaDoc();
25   int sentMsgs = 0;
26   static final int MAXSENTMSGS = 1;
27   Address myAddr;
28
29
30     public FLOWCONTROL() {
31     }
32     public String JavaDoc getName() {
33     return "FLOWCONTROL";
34     }
35
36   /**
37    * Checs if up messages are from myaddr and in the case sends down queued messages or
38    * decremnts sentMsgs if there are no queued messages
39    */
40     public void up(Event evt) {
41     Message msg;
42     switch (evt.getType()) {
43     case Event.SET_LOCAL_ADDRESS: myAddr = (Address) evt.getArg();
44         break;
45
46     case Event.MSG: msg = (Message) evt.getArg();
47          if(log.isDebugEnabled()) log.debug("Message received");
48         if (msg.getSrc().equals(myAddr)) {
49         if (queuedMsgs.size() > 0) {
50              if(log.isDebugEnabled()) log.debug("Message from me received - Queue size was " + queuedMsgs.size());
51             passDown((Event) queuedMsgs.remove(0));
52         } else {
53              if(log.isDebugEnabled()) log.debug("Message from me received - No messages in queue");
54             sentMsgs--;
55         }
56         }
57     }
58     passUp(evt);
59     }
60
61   /**
62    * Checs if it can send the message, else puts the message in the queue.
63    */
64     public void down(Event evt) {
65     Message msg;
66     if (evt.getType()==Event.MSG) {
67         msg = (Message) evt.getArg();
68         if ((msg.getDest() == null) || (msg.getDest().equals(myAddr))) {
69         if (sentMsgs < MAXSENTMSGS) {
70             sentMsgs++;
71              if(log.isDebugEnabled()) log.debug("Message " + sentMsgs + " sent");
72         } else {
73             queuedMsgs.add(evt); //queues message (we add the event to avoid creating a new event to send the message)
74 return;
75         }
76         }
77     }
78     passDown(evt);
79     }
80
81 }
82
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