rtt-estimator.h

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
//
// Copyright (c) 2006 Georgia Tech Research Corporation
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation;
//
// 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
//
// Author: Rajib Bhattacharjea<raj.b@gatech.edu>
//

// Georgia Tech Network Simulator - Round Trip Time Estimation Class
// George F. Riley.  Georgia Tech, Spring 2002


#ifndef RTT_ESTIMATOR_H
#define RTT_ESTIMATOR_H

#include <deque>
#include "ns3/sequence-number.h"
#include "ns3/nstime.h"
#include "ns3/object.h"

namespace ns3 {

class RttHistory {
public:
  RttHistory (SequenceNumber32 s, uint32_t c, Time t);
  RttHistory (const RttHistory& h); // Copy constructor
public:
  SequenceNumber32  seq;  // First sequence number in packet sent
  uint32_t        count;  // Number of bytes sent
  Time            time;   // Time this one was sent
  bool            retx;   // True if this has been retransmitted
};

typedef std::deque<RttHistory> RttHistory_t;

class RttEstimator : public Object {
public:
  static TypeId GetTypeId (void);

  RttEstimator();
  RttEstimator (const RttEstimator&); 

  virtual ~RttEstimator();

  virtual void SentSeq (SequenceNumber32 seq, uint32_t size);

  virtual Time AckSeq (SequenceNumber32 ackSeq);

  virtual void ClearSent ();

  virtual void  Measurement (Time t) = 0;

  virtual Time RetransmitTimeout () = 0;

  virtual Ptr<RttEstimator> Copy () const = 0;

  virtual void IncreaseMultiplier ();

  virtual void ResetMultiplier ();

  virtual void Reset ();

  void SetMinRto (Time minRto);

  Time GetMinRto (void) const;

  void SetCurrentEstimate (Time estimate);

  Time GetCurrentEstimate (void) const;

private:
  SequenceNumber32 m_next;    // Next expected sequence to be sent
  RttHistory_t m_history;     // List of sent packet
  uint16_t m_maxMultiplier;
  Time m_initialEstimatedRtt;

protected:
  Time         m_currentEstimatedRtt;     // Current estimate
  Time         m_minRto;                  // minimum value of the timeout
  uint32_t     m_nSamples;                // Number of samples
  uint16_t     m_multiplier;              // RTO Multiplier
};

class RttMeanDeviation : public RttEstimator {
public:
  static TypeId GetTypeId (void);

  RttMeanDeviation ();

  RttMeanDeviation (const RttMeanDeviation&);

  void Measurement (Time measure);

  Time RetransmitTimeout ();

  Ptr<RttEstimator> Copy () const;

  void Reset ();

  void Gain (double g);

private:
  double       m_gain;       // Filter gain
  Time         m_variance;   // Current variance
};
} // namespace ns3

#endif /* RTT_ESTIMATOR_H */