/* -*- 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 "sequence-number.h"

#include "ns3/nstime.h"

#include "ns3/object.h"

namespace ns3 {

/**

 * \ingroup tcp

 *

 * \brief Implements several variations of round trip time estimators

 */

class RttHistory {

public:

  RttHistory (SequenceNumber s, uint32_t c, Time t);

  RttHistory (const RttHistory& h); // Copy constructor

public:

  SequenceNumber  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 {  //  Base class for all RTT Estimators

public:

  static TypeId GetTypeId (void);

  RttEstimator();

  RttEstimator(const RttEstimator&); // Copy constructor

  virtual ~RttEstimator();

  virtual void SentSeq(SequenceNumber, uint32_t);

  virtual Time AckSeq(SequenceNumber);

  virtual void ClearSent();

  virtual void   Measurement(Time t) = 0;

  virtual Time Estimate() = 0;

  virtual Time RetransmitTimeout() = 0;

  void Init(SequenceNumber s) { next = s;}

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

  virtual void IncreaseMultiplier();

  virtual void ResetMultiplier();

  virtual void Reset();

private:

  SequenceNumber        next;    // Next expected sequence to be sent

  RttHistory_t history; // List of sent packet

  double m_maxMultiplier;

public:

  Time       est;     // Current estimate

  Time       minrto; // minimum value of the timeout

  uint32_t      nSamples;// Number of samples

  double       multiplier;   // RTO Multiplier

};

// The "Mean-Deviation" estimator, as discussed by Van Jacobson

// "Congestion Avoidance and Control", SIGCOMM 88, Appendix A

  //Doc:Class Class {\tt RttMeanDeviation} implements the "Mean--Deviation" estimator

  //Doc:Class as described by Van Jacobson 

  //Doc:Class "Congestion Avoidance and Control", SIGCOMM 88, Appendix A

class RttMeanDeviation : public RttEstimator {

public :

  static TypeId GetTypeId (void);

  RttMeanDeviation ();

  //Doc:Method

  RttMeanDeviation (const RttMeanDeviation&); // Copy constructor

    //Doc:Desc Copy constructor.

    //Doc:Arg1 {\tt RttMeanDeviation} object to copy.

  void Measurement (Time);

  Time Estimate () { return est;}

  Time Variance () { return variance;}

  Time RetransmitTimeout ();

  Ptr<RttEstimator> Copy () const;

  void Reset ();

  void Gain (double g) { gain = g;}

public:

  double       gain;       // Filter gain

  Time       variance;   // Current variance

};

}//namespace ns3

#endif