tbf.cc

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) Xerox Corporation 1997. All rights reserved.
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 * General Public License for more details.
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 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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/* Token Bucket filter which has  3 parameters :
   a. Token Generation rate
   b. Token bucket depth
   c. Max. Queue Length (a finite length would allow this to be used as  policer as packets are dropped after queue gets full)
   */

#include "connector.h" 
#include "packet.h"
#include "queue.h"
#include "tbf.h"

TBF::TBF() :tokens_(0),tbf_timer_(this), init_(1)
{
    q_=new PacketQueue();
    bind_bw("rate_",&rate_);
    bind("bucket_",&bucket_);
    bind("qlen_",&qlen_);
}
    
TBF::~TBF()
{
    if (q_->length() != 0) {
        //Clear all pending timers
        tbf_timer_.cancel();
        //Free up the packetqueue
        for (Packet *p=q_->head();p!=0;p=p->next_) 
            Packet::free(p);
    }
    delete q_;
}


void TBF::recv(Packet *p, Handler *)
{
    //start with a full bucket
    if (init_) {
        tokens_=bucket_;
        lastupdatetime_ = Scheduler::instance().clock();
        init_=0;
    }

    
    hdr_cmn *ch=hdr_cmn::access(p);

    //enque packets appropriately if a non-zero q already exists
    if (q_->length() !=0) {
        if (q_->length() < qlen_) {
            q_->enque(p);
            return;
        }

        drop(p);
        return;
    }

    double tok;
    tok = getupdatedtokens();

    int pktsize = ch->size()<<3;
    if (tokens_ >=pktsize) {
        target_->recv(p);
        tokens_-=pktsize;
    }
    else {
        
        if (qlen_!=0) {
            q_->enque(p);
            tbf_timer_.resched((pktsize-tokens_)/rate_);
        }
        else {
            drop(p);
        }
    }
}

double TBF::getupdatedtokens(void)
{
    double now=Scheduler::instance().clock();
    
    tokens_ += (now-lastupdatetime_)*rate_;
    if (tokens_ > bucket_)
        tokens_=bucket_;
    lastupdatetime_ = Scheduler::instance().clock();
    return tokens_;
}

void TBF::timeout(int)
{
    if (q_->length() == 0) {
        fprintf (stderr,"ERROR in tbf\n");
        abort();
    }
    
    Packet *p=q_->deque();
    double tok;
    tok = getupdatedtokens();
    hdr_cmn *ch=hdr_cmn::access(p);
    int pktsize = ch->size()<<3;

    //We simply send the packet here without checking if we have enough tokens
    //because the timer is supposed to fire at the right time
    target_->recv(p);
    tokens_-=pktsize;

    if (q_->length() !=0 ) {
        p=q_->head();
        hdr_cmn *ch=hdr_cmn::access(p);
        pktsize = ch->size()<<3;
        tbf_timer_.resched((pktsize-tokens_)/rate_);
    }
}

void TBF_Timer::expire(Event* /*e*/)
{
    tbf_->timeout(0);
}


static class TBFClass : public TclClass {
public:
    TBFClass() : TclClass ("TBF") {}
    TclObject* create(int,const char*const*) {
        return (new TBF());
    }
}class_tbf;

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