txop.h

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/*
 * Copyright (c) 2005 INRIA
 *
 * 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: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
 */
 
#ifndef TXOP_H
#define TXOP_H
 
#include "wifi-mac-header.h"
 
#include "ns3/nstime.h"
#include "ns3/object.h"
#include "ns3/traced-value.h"
 
#include <map>
#include <memory>
#include <vector>
 
class EmlsrUlTxopTest;
 
namespace ns3
{
 
class Packet;
class ChannelAccessManager;
class MacTxMiddle;
class WifiMode;
class WifiMacQueue;
class WifiMpdu;
class UniformRandomVariable;
class CtrlBAckResponseHeader;
class WifiMac;
enum WifiMacDropReason : uint8_t; // opaque enum declaration
 
class Txop : public Object
{
  public:
    Txop();
 
    Txop(Ptr<WifiMacQueue> queue);
 
    ~Txop() override;
 
    static TypeId GetTypeId();
 
    typedef Callback<void, WifiMacDropReason, Ptr<const WifiMpdu>> DroppedMpdu;
 
    enum ChannelAccessStatus
    {
        NOT_REQUESTED = 0,
        REQUESTED,
        GRANTED
    };
 
    virtual bool IsQosTxop() const;
 
    virtual void SetWifiMac(const Ptr<WifiMac> mac);
    void SetTxMiddle(const Ptr<MacTxMiddle> txMiddle);
 
    virtual void SetDroppedMpduCallback(DroppedMpdu callback);
 
    Ptr<WifiMacQueue> GetWifiMacQueue() const;
 
    void SetMinCw(uint32_t minCw);
    void SetMinCws(std::vector<uint32_t> minCws);
    void SetMinCw(uint32_t minCw, uint8_t linkId);
    void SetMaxCw(uint32_t maxCw);
    void SetMaxCws(std::vector<uint32_t> maxCws);
    void SetMaxCw(uint32_t maxCw, uint8_t linkId);
    void SetAifsn(uint8_t aifsn);
    void SetAifsns(std::vector<uint8_t> aifsns);
    void SetAifsn(uint8_t aifsn, uint8_t linkId);
    void SetTxopLimit(Time txopLimit);
    void SetTxopLimits(const std::vector<Time>& txopLimits);
    void SetTxopLimit(Time txopLimit, uint8_t linkId);
    uint32_t GetMinCw() const;
    std::vector<uint32_t> GetMinCws() const;
    virtual uint32_t GetMinCw(uint8_t linkId) const;
    uint32_t GetMaxCw() const;
    std::vector<uint32_t> GetMaxCws() const;
    virtual uint32_t GetMaxCw(uint8_t linkId) const;
    uint8_t GetAifsn() const;
    std::vector<uint8_t> GetAifsns() const;
    virtual uint8_t GetAifsn(uint8_t linkId) const;
    Time GetTxopLimit() const;
    std::vector<Time> GetTxopLimits() const;
    Time GetTxopLimit(uint8_t linkId) const;
    void ResetCw(uint8_t linkId);
    void UpdateFailedCw(uint8_t linkId);
 
    virtual void NotifySleep(uint8_t linkId);
    virtual void NotifyOff();
    virtual void NotifyWakeUp(uint8_t linkId);
    virtual void NotifyOn();
 
    /* Event handlers */
    virtual void Queue(Ptr<Packet> packet, const WifiMacHeader& hdr);
    virtual void Queue(Ptr<WifiMpdu> mpdu);
 
    virtual void NotifyChannelAccessed(uint8_t linkId, Time txopDuration = Seconds(0));
    virtual void NotifyChannelReleased(uint8_t linkId);
 
    int64_t AssignStreams(int64_t stream);
 
    virtual ChannelAccessStatus GetAccessStatus(uint8_t linkId) const;
 
    void StartAccessAfterEvent(uint8_t linkId, bool hadFramesToTransmit, bool checkMediumBusy);
 
    static constexpr bool HAD_FRAMES_TO_TRANSMIT =
        true; 
    static constexpr bool DIDNT_HAVE_FRAMES_TO_TRANSMIT =
        false; 
    static constexpr bool CHECK_MEDIUM_BUSY =
        true; 
    static constexpr bool DONT_CHECK_MEDIUM_BUSY =
        false; 
 
    void StartBackoffNow(uint32_t nSlots, uint8_t linkId);
 
    virtual bool HasFramesToTransmit(uint8_t linkId);
 
    void SwapLinks(std::map<uint8_t, uint8_t> links);
 
  protected:
    friend class ChannelAccessManager;
    friend class ::EmlsrUlTxopTest;
 
    void DoDispose() override;
    void DoInitialize() override;
 
    /* Txop notifications forwarded here */
    virtual void NotifyAccessRequested(uint8_t linkId);
 
    virtual void GenerateBackoff(uint8_t linkId);
    void RequestAccess(uint8_t linkId);
 
    uint32_t GetCw(uint8_t linkId) const;
    uint32_t GetBackoffSlots(uint8_t linkId) const;
    Time GetBackoffStart(uint8_t linkId) const;
    void UpdateBackoffSlotsNow(uint32_t nSlots, Time backoffUpdateBound, uint8_t linkId);
 
    struct LinkEntity
    {
        virtual ~LinkEntity() = default;
 
        uint32_t backoffSlots{0};                  
        Time backoffStart{0};                      
        uint32_t cw{0};                            
        uint32_t cwMin{0};                         
        uint32_t cwMax{0};                         
        uint8_t aifsn{0};                          
        Time txopLimit{0};                         
        ChannelAccessStatus access{NOT_REQUESTED}; 
 
        mutable class
        {
            friend void Txop::Queue(Ptr<WifiMpdu>);
            EventId event;
        } accessRequest; 
    };
 
    LinkEntity& GetLink(uint8_t linkId) const;
 
    const std::map<uint8_t, std::unique_ptr<LinkEntity>>& GetLinks() const;
 
    DroppedMpdu m_droppedMpduCallback; 
    Ptr<WifiMacQueue> m_queue;         
    Ptr<MacTxMiddle> m_txMiddle;       
    Ptr<WifiMac> m_mac;                
    Ptr<UniformRandomVariable> m_rng;  
 
    typedef TracedCallback<uint32_t /* value */, uint8_t /* linkId */> BackoffValueTracedCallback;
    typedef TracedCallback<uint32_t /* value */, uint8_t /* linkId */> CwValueTracedCallback;
 
    BackoffValueTracedCallback m_backoffTrace; 
    CwValueTracedCallback m_cwTrace;           
 
  private:
    virtual std::unique_ptr<LinkEntity> CreateLinkEntity() const;
 
    std::map<uint8_t, std::unique_ptr<LinkEntity>>
        m_links; 
};
 
} // namespace ns3
 
#endif /* TXOP_H */