/Users/yzchen/ns/ns-allinone-2.33/ns-2.33/queue/semantic-packetqueue.h

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 * Copyright (c) 1996-1997 The Regents of the University of California.
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 *      This product includes software developed by the Daedalus 
 *      Research Group at the University of California, Berkeley.
 * 4. Neither the name of the University nor of the Research Group may be used
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 * @(#) $Header: /cvsroot/nsnam/ns-2/queue/semantic-packetqueue.h,v 1.9 2002/05/07 18:28:28 haldar Exp $ (UCB)
 */

#ifndef ns_semantic_packetqueue_h
#define ns_semantic_packetqueue_h

#include "object.h"
#include "connector.h"
#include "packet.h"
#include "queue.h"
#include "flags.h"
#include "random.h"
#include "tcp.h"

class AckReconsController;

/*
 * This flavor of PacketQueue includes several buffer management and
 * scheduling policies that are based on higher-layer semantics (e.g.,
 * TCP semantics) of packets.
 */
class SemanticPacketQueue : public PacketQueue {
  public:
        SemanticPacketQueue();
        int command(int argc, const char*const* argv);
        /* deque TCP acks before any other type of packet */
        Packet* deque_acksfirst();
        /* determine whether two packets belong to the same connection */
        inline int compareFlows(hdr_ip *ip1, hdr_ip *ip2) {
                return ((ip1->saddr() == ip2->saddr()) &&
                        (ip1->sport() == ip2->sport()) &&
                        (ip1->daddr() == ip2->daddr()) && 
                        (ip1->dport() == ip2->dport())); 
        }
        /*
         * When a new ack is enqued, purge older acks (as determined by the 
         * sequence number of the ack field) from the queue. The enqued ack
         * remains at the tail of the queue, unless replace_head is true, in 
         * which case the new ack takes the place of the old ack closest to
         * the head of the queue.
         */
        void filterAcks(Packet *pkt, int replace_head); 

        /* check whether packet is marked */
        int isMarked(Packet *p);
        /* pick out the index'th packet of the right kind (marked/unmarked) */
        Packet *lookup(int index, int markedFlag);
        /* pick packet for ECN notification (either marking or dropping) */
        Packet *pickPacketForECN(Packet *pkt);
        /* pick a packet to drop when the queue is full */
        Packet *pickPacketToDrop();

        /* 
         * Remove a specific packet given pointers to it and its predecessor
         * in the queue. p and/or pp may be NULL.
         */
        void remove(Packet* p, Packet* pp);

        inline Packet* head() { return head_; }

        /* count of packets of various types */
        int ack_count;          /* number of TCP acks in the queue */
        int data_count;         /* number of non-ack packets in the queue */
        int acks_to_send;       /* number of ack to send in current schedule */
        int marked_count_;      /* number of marked packets */
        int unmarked_count_;    /* number of unmarked packets */

        /* 
         * These indicator variables are bound in derived objects and
         * define queueing/scheduling polcies.
         */
        int acksfirst_;         /* deque TCP acks before any other data */
        int filteracks_;        /* purge old acks when new one arrives */
        int reconsAcks_;        /* set up queue as an ack recontructor */
        int replace_head_;      /* new ack should take the place of old ack
                                   closest to the head */
        int priority_drop_;     /* drop marked (low priority) packets first */
        int random_drop_;       /* pick packet to drop at random */
        int random_ecn_;        /* pick packet for ECN at random */
        virtual Packet* deque();
        Packet* enque(Packet *); // Returns prev tail
        virtual inline void enque_head(Packet *p) {
                if (len_ == 0)
                        PacketQueue::enque(p);
                else {
                        p->next_ = head_;
                        head_ = p;
                        ++len_;
                }
        }
        virtual void remove(Packet *);
        AckReconsController *reconsCtrl_;
};

#endif