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.
 *
 * License is granted to copy, to use, and to make and to use derivative
 * works for research and evaluation purposes, provided that Xerox is
 * acknowledged in all documentation pertaining to any such copy or
 * derivative work. Xerox grants no other licenses expressed or
 * implied. The Xerox trade name should not be used in any advertising
 * without its written permission. 
 *
 * XEROX CORPORATION MAKES NO REPRESENTATIONS CONCERNING EITHER THE
 * MERCHANTABILITY OF THIS SOFTWARE OR THE SUITABILITY OF THIS SOFTWARE
 * FOR ANY PARTICULAR PURPOSE.  The software is provided "as is" without
 * express or implied warranty of any kind.
 *
 * These notices must be retained in any copies of any part of this
 * software. 
 */

/* 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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