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Java > Open Source Codes > com > tc > net > protocol > delivery > ReceiveStateMachine


1 /*
2  * All content copyright (c) 2003-2006 Terracotta, Inc., except as may otherwise be noted in a separate copyright notice. All rights reserved.
3  */
4 package com.tc.net.protocol.delivery;
5
6 import EDU.oswego.cs.dl.util.concurrent.SynchronizedLong;
7
8 import com.tc.util.Assert;
9
10 /**
11  *
12  */
13 public class ReceiveStateMachine extends AbstractStateMachine {
14   private final State MESSAGE_WAIT_STATE = new MessageWaitState();
15
16   private final SynchronizedLong received = new SynchronizedLong(-1);
17   private final OOOProtocolMessageDelivery delivery;
18
19   public ReceiveStateMachine(OOOProtocolMessageDelivery delivery) {
20     this.delivery = delivery;
21   }
22
23   public void execute(OOOProtocolMessage msg) {
24     getCurrentState().execute(msg);
25   }
26
27   protected State initialState() {
28     return MESSAGE_WAIT_STATE;
29   }
30
31   private class MessageWaitState extends AbstractState {
32
33     public void execute(OOOProtocolMessage protocolMessage) {
34       if (protocolMessage.isAckRequest()) {
35         delivery.sendAck(received.get());
36         return;
37       }
38
39       final long r = protocolMessage.getSent();
40       final long curRecv = received.get();
41       Assert.eval(r >= curRecv);
42       if (r == curRecv) {
43         //do nothing we already got it
44 } else {
45         putMessage(protocolMessage);
46         final long next = received.increment();
47         delivery.sendAck(next);
48       }
49     }
50   }
51
52   private void putMessage(OOOProtocolMessage msg) {
53     this.delivery.receiveMessage(msg);
54   }
55
56 }
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