queue.cc

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1996-1997 The Regents of the University of California.
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 *      This product includes software developed by the Network Research
 *      Group at Lawrence Berkeley National Laboratory.
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#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/queue/queue.cc,v 1.27 2003/01/28 23:31:03 sfloyd Exp $ (LBL)";
#endif

#include "queue.h"
#include <math.h>
#include <stdio.h>

void PacketQueue::remove(Packet* target)
{
        for (Packet *pp= 0, *p= head_; p; pp= p, p= p->next_) {
                if (p == target) {
                        if (!pp) deque();
                        else {
                                if (p == tail_) 
                                        tail_= pp;
                                pp->next_= p->next_;
                                --len_;
                                bytes_ -= hdr_cmn::access(p)->size();
                        }
                        return;
                }
        }
        fprintf(stderr, "PacketQueue:: remove() couldn't find target\n");
        abort();
}

/*
 * Remove packet pkt located after packet prev on the queue.  Either p or prev
 * could be NULL.  If prev is NULL then pkt must be the head of the queue.
 */
void PacketQueue::remove(Packet* pkt, Packet *prev) //XXX: screwy
{
        if (pkt) {
                if (head_ == pkt)
                        PacketQueue::deque(); /* decrements len_ internally */
                else {
                        prev->next_ = pkt->next_;
                        if (tail_ == pkt)
                                tail_ = prev;
                        --len_;
                        bytes_ -= hdr_cmn::access(pkt)->size();
                }
        }
        return;
}

void QueueHandler::handle(Event*)
{
        queue_.resume();
}

Queue::~Queue() {
}

Queue::Queue() : Connector(), blocked_(0), unblock_on_resume_(1), qh_(*this),
        pq_(0), last_change_(0), /* temporarily NULL */
        old_util_(0)
{
        bind("limit_", &qlim_);
        bind("util_weight_", &util_weight_);
        bind_bool("blocked_", &blocked_);
        bind_bool("unblock_on_resume_", &unblock_on_resume_);
}

void Queue::recv(Packet* p, Handler*)
{
        double now = Scheduler::instance().clock();
        enque(p);
        if (!blocked_) {
                /*
                 * We're not blocked.  Get a packet and send it on.
                 * We perform an extra check because the queue
                 * might drop the packet even if it was
                 * previously empty!  (e.g., RED can do this.)
                 */
                p = deque();
                if (p != 0) {
                        utilUpdate(last_change_, now, blocked_);
                        last_change_ = now;
                        blocked_ = 1;
                        target_->recv(p, &qh_);
                }
        }
}

void Queue::utilUpdate(double int_begin, double int_end, int link_state) {
double decay;

        decay = exp(-util_weight_ * (int_end - int_begin));
        old_util_ = link_state + (old_util_ - link_state) * decay;

}

double Queue::utilization(void) 
{
        double now = Scheduler::instance().clock();
        
        utilUpdate(last_change_, now, blocked_);
        last_change_ = now;

        return old_util_;
                        
}

void Queue::updateStats(int queuesize)
{
        double now = Scheduler::instance().clock();
        double newtime = now - total_time_;
        if (newtime > 0.0) {
                double oldave = true_ave_;
                double oldtime = total_time_;
                double newtime = now - total_time_;
                true_ave_ = (oldtime * oldave + newtime * queuesize) /now;
                total_time_ = now;
        }
}

void Queue::resume()
{
        double now = Scheduler::instance().clock();
        Packet* p = deque();
        if (p != 0) {
                target_->recv(p, &qh_);
        } else {
                if (unblock_on_resume_) {
                        utilUpdate(last_change_, now, blocked_);
                        last_change_ = now;
                        blocked_ = 0;
                }
                else {
                        utilUpdate(last_change_, now, blocked_);
                        last_change_ = now;
                        blocked_ = 1;
                }
        }
}

void Queue::reset()
{
        Packet* p;
        total_time_ = 0.0;
        true_ave_ = 0.0;
        while ((p = deque()) != 0)
                drop(p);
}

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