codel-queue-disc.h

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2012 Andrew McGregor
 *
 * 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
 *
 * Codel, the COntrolled DELay Queueing discipline
 * Based on ns2 simulation code presented by Kathie Nichols
 *
 * This port based on linux kernel code by
 * Authors: Dave Täht <d@taht.net>
 *      Eric Dumazet <edumazet@google.com>
 *
 * Ported to ns-3 by: Andrew McGregor <andrewmcgr@gmail.com>
 */

#ifndef CODEL_H
#define CODEL_H

#include "ns3/queue-disc.h"
#include "ns3/nstime.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/traced-value.h"
#include "ns3/trace-source-accessor.h"

class CoDelQueueDiscNewtonStepTest;  // Forward declaration for unit test
class CoDelQueueDiscControlLawTest;  // Forward declaration for unit test

namespace ns3 {

static const int  CODEL_SHIFT = 10;

#define DEFAULT_CODEL_LIMIT 1000
#define REC_INV_SQRT_BITS (8 * sizeof(uint16_t))
#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)

class TraceContainer;

class CoDelQueueDisc : public QueueDisc
{
public:
  static TypeId GetTypeId (void);

  CoDelQueueDisc ();

  virtual ~CoDelQueueDisc ();

  enum QueueDiscMode
  {
    QUEUE_DISC_MODE_PACKETS,     
    QUEUE_DISC_MODE_BYTES,       
  };

  void SetMode (QueueDiscMode mode);

  QueueDiscMode GetMode (void);

  uint32_t GetQueueSize (void);

  Time GetTarget (void);

  Time GetInterval (void);

  uint32_t GetDropNext (void);

  // Reasons for dropping packets
  static constexpr const char* TARGET_EXCEEDED_DROP = "Target exceeded drop";  
  static constexpr const char* OVERLIMIT_DROP = "Overlimit drop";  

private:
  friend class::CoDelQueueDiscNewtonStepTest;  // Test code
  friend class::CoDelQueueDiscControlLawTest;  // Test code
  virtual bool DoEnqueue (Ptr<QueueDiscItem> item);

  virtual Ptr<QueueDiscItem> DoDequeue (void);

  virtual Ptr<const QueueDiscItem> DoPeek (void) const;
  virtual bool CheckConfig (void);

  void NewtonStep (void);

  uint32_t ControlLaw (uint32_t t);

  bool OkToDrop (Ptr<QueueDiscItem> item, uint32_t now);

  bool CoDelTimeAfter (uint32_t a, uint32_t b);
  bool CoDelTimeAfterEq (uint32_t a, uint32_t b);
  bool CoDelTimeBefore (uint32_t a, uint32_t b);
  bool CoDelTimeBeforeEq (uint32_t a, uint32_t b);

  uint32_t Time2CoDel (Time t);

  virtual void InitializeParams (void);

  uint32_t m_maxPackets;                  
  uint32_t m_maxBytes;                    
  uint32_t m_minBytes;                    
  Time m_interval;                        
  Time m_target;                          
  TracedValue<uint32_t> m_count;          
  TracedValue<uint32_t> m_lastCount;      
  TracedValue<bool> m_dropping;           
  uint16_t m_recInvSqrt;                  
  uint32_t m_firstAboveTime;              
  TracedValue<uint32_t> m_dropNext;       
  uint32_t m_state1;                      
  uint32_t m_state2;                      
  uint32_t m_state3;                      
  uint32_t m_states;                      
  QueueDiscMode m_mode;                   
};

} // namespace ns3

#endif /* CODEL_H */