libns3-dev 3.27+dfsg-1 / usr / include / ns3.27 / ns3 / tcp-ledbat.h

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2016 NITK Surathkal
 *
 * 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: Ankit Deepak <adadeepak8@gmail.com>
 *
 */

#ifndef TCP_LEDBAT_H
#define TCP_LEDBAT_H

#include <vector>
#include "ns3/tcp-congestion-ops.h"
#include "ns3/event-id.h"

namespace ns3 {

/**
 * \ingroup congestionOps
 *
 * \brief An implementation of LEDBAT
 */

class TcpLedbat : public TcpNewReno
{
private:
  /**
   * \brief The slowstart types
   */
  enum SlowStartType
  {
    DO_NOT_SLOWSTART,           //!< Do not Slow Start
    DO_SLOWSTART,               //!< Do NewReno Slow Start
  };

  /**
   * \brief The state of LEDBAT. If LEDBAT is not in VALID_OWD state, it falls to
   *        default congestion ops.
   */
  enum State
  {
    LEDBAT_VALID_OWD  = (1 << 1),  //!< If valid timestamps are present
    LEDBAT_CAN_SS     = (1 << 3)   //!< If LEDBAT allows Slow Start
  };

public:
  /**
   * \brief Get the type ID.
   * \return the object TypeId
   */
  static TypeId GetTypeId (void);

  /**
   * Create an unbound tcp socket.
   */
  TcpLedbat (void);

  /**
   * \brief Copy constructor
   * \param sock the object to copy
   */
  TcpLedbat (const TcpLedbat& sock);

  /**
   * \brief Destructor
   */
  virtual ~TcpLedbat (void);

  /**
   * \brief Get the name of the TCP flavour
   *
   * \return The name of the TCP
   */
  virtual std::string GetName () const;

  /**
   * \brief Get information from the acked packet
   *
   * \param tcb internal congestion state
   * \param segmentsAcked count of segments ACKed
   * \param rtt The estimated rtt
   */
  virtual void PktsAcked (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked,
                          const Time& rtt);

  /**
   * \brief Get the slow start threshold
   *
   * \param tcb internal congestion state
   * \param bytesInFlight bytes in flight
   *
   * \return The slow start threshold
   */
  virtual uint32_t GetSsThresh (Ptr<const TcpSocketState> tcb,
                                uint32_t bytesInFlight);
  virtual Ptr<TcpCongestionOps> Fork ();

  /**
   * \brief Adjust cwnd following LEDBAT algorithm
   *
   * \param tcb internal congestion state
   * \param segmentsAcked count of segments ACKed
   */
  virtual void IncreaseWindow (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked);

  /**
   * \brief Change the Slow Start Capability
   *
   * \param doSS Slow Start Option
   */
  void SetDoSs (SlowStartType doSS);

protected:
  /**
   * \brief Reduce Congestion
   *
   * \param tcb internal congestion state
   * \param segmentsAcked count of segments ACKed
   */
  virtual void CongestionAvoidance (Ptr<TcpSocketState> tcb, uint32_t segmentsAcked);

private:
  /**
   *\brief Buffer structure to store delays
   */
  struct OwdCircBuf
  {
    std::vector<uint32_t> buffer; //!< Vector to store the delay
    uint32_t min;  //!< The index of minimum value
  };

  /**
   * \brief Initialise a new buffer
   *
   * \param buffer The buffer to be initialised
   */
  void InitCircBuf (struct OwdCircBuf &buffer);

  /// Filter function used by LEDBAT for current delay
  typedef uint32_t (*FilterFunction)(struct OwdCircBuf &);

  /**
   * \brief Return the minimum delay of the buffer
   *
   * \param b The buffer
   * \return The minimum delay
   */
  static uint32_t MinCircBuf (struct OwdCircBuf &b);

  /**
   * \brief Return the value of current delay
   *
   * \param filter The filter function
   * \return The current delay
   */
  uint32_t CurrentDelay (FilterFunction filter);

  /**
   * \brief Return the value of base delay
   *
   * \return The base delay
   */
  uint32_t BaseDelay ();

  /**
   * \brief Add new delay to the buffers
   *
   * \param cb The buffer
   * \param owd The new delay
   * \param maxlen The maximum permitted length
   */
  void AddDelay (struct OwdCircBuf &cb, uint32_t owd, uint32_t maxlen);

  /**
   * \brief Update the base delay buffer
   *
   * \param owd The delay
   */
  void UpdateBaseDelay (uint32_t owd);

  Time m_target;                     //!< Target Queue Delay
  double m_gain;                     //!< GAIN value from RFC
  SlowStartType m_doSs;              //!< Permissible Slow Start State
  uint32_t m_baseHistoLen;           //!< Length of base delay history buffer
  uint32_t m_noiseFilterLen;         //!< Length of current delay buffer
  uint64_t m_lastRollover;           //!< Timestamp of last added delay
  int32_t m_sndCwndCnt;              //!< The congestion window addition parameter
  struct OwdCircBuf m_baseHistory;   //!< Buffer to store the base delay
  struct OwdCircBuf m_noiseFilter;   //!< Buffer to store the current delay
  uint32_t m_flag;                   //!< LEDBAT Flag
};

} // namespace ns3

#endif /* TCP_LEDBAT_H */