pi.h

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 *  This product includes software developed by the Computer Systems
 *  Engineering Group at Lawrence Berkeley Laboratory.
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/*
 * Based on PI controller described in:
 * C. Hollot, V. Misra, D. Towsley and W. Gong. 
 * On Designing Improved Controllers for AQM Routers
 * Supporting TCP Flows, 
 * INFOCOMM 2001. 
 */

#ifndef ns_pi_h
#define ns_pi_h

#undef setbit

#include "queue.h"
#include "trace.h"
#include "timer-handler.h"

#define DTYPE_NONE  0   /* ok, no drop */
#define DTYPE_FORCED    1   /* a "forced" drop */
#define DTYPE_UNFORCED  2   /* an "unforced" (random) drop */

// Insert APPLE specific macro here
//
#if defined( __MACH__ ) && defined( __APPLE__ )
#undef setbit
#endif

/*
 * Early drop parameters, supplied by user
 */
struct edp_pi {
    /*
     * User supplied.
     */
    int mean_pktsize;   /* avg pkt size, linked into Tcl */
    int bytes;      /* true if queue in bytes, false if packets */
    int setbit;     /* true to set congestion indication bit */
    double a, b;         /* parameters to pi controller */
    double w;               /* sampling frequency (# of times per second) */ 
    double qref;        /* desired queue size */
    edp_pi(): mean_pktsize(0), bytes(0), setbit(0), a(0.0), b(0.0), w(0.0), qref(0.0) { }
};

/*
 * Early drop variables, maintained by PI
 */
struct edv_pi {
    TracedDouble v_prob;    /* prob. of packet drop before "count". */
    int count;      /* # of packets since last drop */
    int count_bytes;    /* # of bytes since last drop */
    int qold;
    edv_pi() : v_prob(0.0), count(0), count_bytes(0), qold(0) { }
};

class LinkDelay;
class PIQueue ; 

class PICalcTimer : public TimerHandler {
public:
        PICalcTimer(PIQueue *a) : TimerHandler() { a_ = a; }
        virtual void expire(Event *e);
protected:
        PIQueue *a_;
};

class PIQueue : public Queue {
 
 friend class PICalcTimer;
 public:    
    PIQueue(const char * = "Drop");
 protected:
    int command(int argc, const char*const* argv);
    void enque(Packet* pkt);
    virtual Packet *pickPacketForECN(Packet* pkt);
    virtual Packet *pickPacketToDrop();
    Packet* deque();
    void reset();
    int drop_early(Packet* pkt, int qlen);
    double calculate_p();
    PICalcTimer CalcTimer;

    LinkDelay* link_;   /* outgoing link */
    int fifo_;      /* fifo queue? */
    PacketQueue *q_;    /* underlying (usually) FIFO queue */
        
    int qib_;   /* bool: queue measured in bytes? */
    NsObject* de_drop_; /* drop_early target */

    //added to be able to trace EDrop Objects - ratul
    //the other events - forced drop, enque and deque are traced by a different mechanism.
    NsObject * EDTrace;    //early drop trace
    char traceType[20];    //the preferred type for early drop trace. 
                           //better be less than 19 chars long
    Tcl_Channel tchan_; /* place to write trace records */
    TracedInt curq_;    /* current qlen seen by arrivals */
    void trace(TracedVar*); /* routine to write trace records */

    edp_pi edp_;    /* early-drop params */
    edv_pi edv_;        /* early-drop variables */

    int first_reset_;       /* first time reset() is called */

};

#endif

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