codel-queue-disc.h

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/*
 * 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 "queue-disc.h"
 
#include "ns3/nstime.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/trace-source-accessor.h"
#include "ns3/traced-value.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();
 
    CoDelQueueDisc();
 
    ~CoDelQueueDisc() override;
 
    Time GetTarget();
 
    Time GetInterval();
 
    uint32_t GetDropNext();
 
    // Reasons for dropping packets
    static constexpr const char* TARGET_EXCEEDED_DROP =
        "Target exceeded drop";                                     
    static constexpr const char* OVERLIMIT_DROP = "Overlimit drop"; 
    // Reasons for marking packets
    static constexpr const char* TARGET_EXCEEDED_MARK =
        "Target exceeded mark"; 
    static constexpr const char* CE_THRESHOLD_EXCEEDED_MARK =
        "CE threshold exceeded mark"; 
 
  private:
    friend class ::CoDelQueueDiscNewtonStepTest; // Test code
    friend class ::CoDelQueueDiscControlLawTest; // Test code
    bool DoEnqueue(Ptr<QueueDiscItem> item) override;
 
    Ptr<QueueDiscItem> DoDequeue() override;
 
    bool CheckConfig() override;
 
    static uint16_t NewtonStep(uint16_t recInvSqrt, uint32_t count);
 
    static uint32_t ControlLaw(uint32_t t, uint32_t interval, uint32_t recInvSqrt);
 
    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);
 
    void InitializeParams() override;
 
    bool m_useEcn;       
    bool m_useL4s;       
    uint32_t m_minBytes; 
    Time m_interval;     
    Time m_target;       
    Time m_ceThreshold;  
    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;  
};
 
} // namespace ns3
 
#endif /* CODEL_H */