drop-tail.cc

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1994 Regents of the University of California.
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 *    must display the following acknowledgement:
 *      This product includes software developed by the Computer Systems
 *      Engineering Group at Lawrence Berkeley Laboratory.
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#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/queue/drop-tail.cc,v 1.15 2003/01/16 19:02:54 sfloyd Exp $ (LBL)";
#endif

#include "drop-tail.h"

static class DropTailClass : public TclClass {
 public:
        DropTailClass() : TclClass("Queue/DropTail") {}
        TclObject* create(int, const char*const*) {
                return (new DropTail);
        }
} class_drop_tail;

void DropTail::reset()
{
        Queue::reset();
}

int 
DropTail::command(int argc, const char*const* argv) {

        if (argc==2) {
                if (strcmp(argv[1], "printstats") == 0) {
                        print_summarystats();
                        return (TCL_OK);
                }
        }
        if (argc == 3) {
                if (!strcmp(argv[1], "packetqueue-attach")) {
                        delete q_;
                        if (!(q_ = (PacketQueue*) TclObject::lookup(argv[2])))
                                return (TCL_ERROR);
                        else {
                                pq_ = q_;
                                return (TCL_OK);
                        }
                }
        }
        return Queue::command(argc, argv);
}

/*
 * drop-tail
 */
void DropTail::enque(Packet* p)
{
        if (summarystats) {
                Queue::updateStats(qib_?q_->byteLength():q_->length());
        }

        int qlimBytes = qlim_ * mean_pktsize_;
        if ((!qib_ && (q_->length() + 1) >= qlim_) ||
        (qib_ && (q_->byteLength() + hdr_cmn::access(p)->size()) >= qlimBytes)){
                // if the queue would overflow if we added this packet...
                if (drop_front_) { /* remove from head of queue */
                        q_->enque(p);
                        Packet *pp = q_->deque();
                        drop(pp);
                } else {
                        drop(p);
                }
        } else {
                q_->enque(p);
        }
}

Packet* DropTail::deque()
{
        if (summarystats && &Scheduler::instance() != NULL) {
                Queue::updateStats(qib_?q_->byteLength():q_->length());
        }
        return q_->deque();
}

void DropTail::print_summarystats()
{
        //double now = Scheduler::instance().clock();
        printf("True average queue: %5.3f", true_ave_);
        if (qib_)
                printf(" (in bytes)");
        printf(" time: %5.3f\n", total_time_);
}

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