examples/bittorrent/Tracker.java

   1 package bittorrent;
   2 import java.util.ArrayList;
   3 import java.util.Iterator;
   4
   5 import org.simgrid.msg.Comm;
   6 import org.simgrid.msg.Host;
   7 import org.simgrid.msg.Process;
   8 import org.simgrid.msg.Msg;
   9 import org.simgrid.msg.MsgException;
  10 import org.simgrid.msg.Task;
  11
  12 import org.simgrid.msg.RngStream;
  13 /**
  14  * Tracker, handle requests from peers.
  15  */
  16 public class Tracker extends Process {
  17         protected RngStream stream;
  18         /**
  19          * Peers list
  20          */
  21         protected ArrayList<Integer> peersList;
  22         /**
  23          * End time for the simulation
  24          */
  25         protected double deadline;
  26         /**
  27          * Current comm received
  28          */
  29         protected Comm commReceived = null;
  30
  31         public Tracker(Host host, String name, String[]args) {
  32                 super(host,name,args);
  33         }
  34
  35         @Override
  36         public void main(String[] args) throws MsgException {
  37                 if (args.length != 1) {
  38                         Msg.info("Wrong number of arguments for the tracker.");
  39                         return;
  40                 }
  41                 //Build the RngStream object for randomness
  42                 stream = new RngStream("tracker");
  43                 //Retrieve the end time
  44                 deadline = Double.valueOf(args[0]);
  45                 //Building peers array
  46                 peersList = new ArrayList<Integer>();
  47
  48                 Msg.info("Tracker launched.");
  49                 while (Msg.getClock() < deadline) {
  50                         if (commReceived == null) {
  51                                 commReceived = Task.irecv(Common.TRACKER_MAILBOX);
  52                         }
  53                         try {
  54                                 if (commReceived.test()) {
  55                                         Task task = commReceived.getTask();
  56                                         if (task instanceof TrackerTask) {
  57                                                 TrackerTask tTask = (TrackerTask)task;
  58                                                 //Sending peers to the peer
  59                                                 //TODO: Send RANDOM pairs using RngStreams.
  60                                                 int nbPeers = 0;
  61                                                 while (nbPeers < Common.MAXIMUM_PAIRS && nbPeers < peersList.size()) {
  62                                                         int nextPeer;
  63                                                         do {
  64                                                                 nextPeer = stream.randInt(0, peersList.size() - 1);
  65                                                         } while (tTask.peers.contains(nextPeer));
  66                                                         tTask.peers.add(peersList.get(nextPeer));
  67                                                         nbPeers++;
  68                                                 }
  69                                                 //Adding the peer to our list
  70                                                 peersList.add(tTask.peerId);
  71                                                 tTask.type = TrackerTask.Type.ANSWER;
  72                                                 //Setting the interval
  73                                                 tTask.interval = Common.TRACKER_QUERY_INTERVAL;
  74                                                 //Sending the task back to the peer
  75                                                 tTask.dsend(tTask.mailbox);
  76                                         }
  77                                         commReceived = null;
  78                                 }
  79                                 else {
  80                                         waitFor(1);
  81                                 }
  82                         }
  83                         catch (MsgException e) {
  84                                 commReceived = null;
  85                         }
  86                 }
  87                 Msg.info("Tracker is leaving");
  88         }
  89
  90 }