Package dijjer.io.xfer

Source Code of dijjer.io.xfer.BlockReceiver

/*
* Dijjer - A Peer to Peer HTTP Cache
* Copyright (C) 2004,2005 Change.Tv, Inc
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
package dijjer.io.xfer;

import java.util.HashMap;
import java.util.LinkedList;
import dijjer.io.comm.DMT;
import dijjer.io.comm.Message;
import dijjer.io.comm.MessageFilter;
import dijjer.io.comm.Peer;
import dijjer.io.comm.RetrievalException;
import dijjer.io.comm.RoutingTable;
import dijjer.io.comm.UdpSocketManager;
import dijjer.util.BitArray;
import dijjer.util.Buffer;
import dijjer.util.logging.Logger;

/**
* @author ian
*
* To change the template for this generated type comment go to Window - Preferences - Java - Code Generation - Code and
* Comments
*/
public class BlockReceiver {

  public static final int RECEIPT_TIMEOUT = 5000;
  public static final int INITIAL_RECEIPT_TIMEOUT = 15000;
  // TODO: This should be proportional to the calculated round-trip-time, not a constant
  public static final int MAX_ROUND_TRIP_TIME = RECEIPT_TIMEOUT;
  public static final int MAX_CONSECUTIVE_MISSING_PACKET_REPORTS = 2;
  public static final int MAX_SEND_INTERVAL = 500;
  PartiallyReceivedBlock _prb;
  Peer _sender;
  int _uid;
  UdpSocketManager _usm;
  /** packet : Integer -> reportTime : Long * */
  HashMap _recentlyReportedMissingPackets = new HashMap();

  public BlockReceiver(UdpSocketManager usm, Peer sender, int uid, PartiallyReceivedBlock prb) {
    _sender = sender;
    _prb = prb;
    _uid = uid;
    _usm = usm;
  }

  public byte[] receive() throws RetrievalException {
    int consecutiveMissingPacketReports = 0;
    MessageFilter f = MessageFilter.create(INITIAL_RECEIPT_TIMEOUT, DMT.packetTransmit)
              .setField(DMT.UID, _uid)
              .addType(DMT.allSent)
              .addType(DMT.sendAborted);
    while (!_prb.allReceived()) {
      Message m1 = _usm.waitFor(f);
      // Get ready for the next packet
      f = MessageFilter.create(RECEIPT_TIMEOUT, DMT.packetTransmit)
        .setField(DMT.UID, _uid)
        .addType(DMT.allSent)
        .addType(DMT.sendAborted);
      // The faster we finish the rest of this loop the better!
      if ((m1 != null) && (m1.getSpec().equals(DMT.packetTransmit))) {
        consecutiveMissingPacketReports = 0;
        // packetTransmit received
        int packetNo = m1.getInt(DMT.PACKET_NO);
        BitArray sent = (BitArray) m1.getObject(DMT.SENT);
        Buffer data = (Buffer) m1.getObject(DMT.DATA);
        _prb.addPacket(packetNo, data);
        // Remove it from rrmp if its in there
        _recentlyReportedMissingPackets.remove(new Integer(packetNo));
        // Skip checks except for 1 out of 16 packets until we get to the end
        if ((_prb.numReceived() < (_prb.getNumPackets() - 16))
          && (packetNo % 16 != 0))
          continue;
        // Check that we have what the sender thinks we have
        LinkedList missing = new LinkedList();
        for (int x = 0; x < sent.getSize(); x++) {
          if (sent.bitAt(x) && !_prb.isReceived(x)) {
            // Sender thinks we have a block which we don't, but have we already
            // re-requested it recently?
            Long resendTime = (Long) _recentlyReportedMissingPackets.get(new Integer(x));
            if ((resendTime == null) || (System.currentTimeMillis() > resendTime.longValue())) {
              // Make a note of the earliest time we should resend this,
              // based on the number of other packets we are already waiting for
              long resendWait = System.currentTimeMillis()
                  + (10*MAX_ROUND_TRIP_TIME + (_recentlyReportedMissingPackets.size() * MAX_SEND_INTERVAL));
              _recentlyReportedMissingPackets.put(new Integer(x), (new Long(resendWait)));
              missing.add(new Integer(x));
            }
          }
        }
        if (missing.size() > 0) {
          Message mn = DMT.createMissingPacketNotification(_uid, missing);
          _usm.send(_sender, mn);
          consecutiveMissingPacketReports++;
          if (missing.size() > 50) {
            Logger.warning("Excessive packet loss : " + mn);
          }
        }
        continue;
      }
      if ((m1 != null) && m1.getSpec().equals(DMT.sendAborted)) {
        _prb.abort(m1.getInt(DMT.REASON), m1.getString(DMT.DESCRIPTION));
        throw new RetrievalException(m1.getInt(DMT.REASON), m1.getString(DMT.DESCRIPTION));
      }
      if ((m1 == null) || (m1.getSpec().equals(DMT.allSent))) {
        if (consecutiveMissingPacketReports >= MAX_CONSECUTIVE_MISSING_PACKET_REPORTS) {
          _prb.abort(RetrievalException.SENDER_DIED, "Sender unresponsive to resend requests");
          LinkedList rem = new LinkedList();
          rem.add(_sender);
          // TODO: This is a stupid work around for BlockTransferTest and needs to be fixed
          if (RoutingTable.getRoutingTable() != null)
          RoutingTable.getRoutingTable().removePeers(rem, "Failed to send data after acking request");
          throw new RetrievalException(RetrievalException.SENDER_DIED,
              "Sender unresponsive to resend requests");
        }
        LinkedList missing = new LinkedList();
        for (int x = 0; x < _prb.getNumPackets(); x++) {
          if (!_prb.isReceived(x)) {
            missing.addFirst(new Integer(x));
          }
        }
        Message mn = DMT.createMissingPacketNotification(_uid, missing);
        _usm.send(_sender, mn);
        consecutiveMissingPacketReports++;
        if (missing.size() > 50) {
          Logger.warning("Sending large missingPacketNotification to " + _sender
              + " due to packet receiver timeout after " + RECEIPT_TIMEOUT + "ms having received "
              + _prb.numReceived());
        }
      }
    }
    _usm.send(_sender, DMT.createAllReceived(_uid));
    return _prb.getBlock();
  }
}
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