//
// Copyright Š 2014 PRISTINE Consortium (http://ict-pristine.eu)
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program. If not, see http://www.gnu.org/licenses/.
//
#include "REDDropper.h"
Define_Module(REDDropper);
void REDDropper::onPolicyInit()
{
monitor = dynamic_cast<REDMonitor*>(qMonPolicy);
if (monitor == NULL)
{
EV << "!!! REDDropper has to be used in conjecture with REDMonitor!" << endl;
}
}
/**
* Either drops or marks the last PDU in given queue (depending on the NED setting).
*
* @param queue target queue
* @return true for PDU drop, false for PDU mark
*/
bool REDDropper::dropOrMark(RMTQueue* queue)
{
if (par("marking").boolValue() == true)
{
EV << "REDDropper: Marking the last message in " << queue->getFullName()
<< " with an ECN bit." << endl;
queue->markCongestionOnLast();
return false;
}
else
{
EV << "REDDropper: executing tail drop in " << queue->getFullName() << endl;
return true;
}
}
/**
* Decides whether to mark/drop last incoming packet in a queue.
*
* @param queue target queue
* @return true for PDU drop, false for PDU mark
*/
bool REDDropper::run(RMTQueue* queue)
{
if (monitor == NULL)
{
return false;
}
// gather some variables from the queue, the monitoring policy and the NED module
const char* qname = queue->getFullName();
int length = queue->getLength();
int minThresh = queue->getThreshLength();
int maxThresh = queue->getMaxLength();
double avr = monitor->qAvgLengths[queue];
int count = monitor->qCounters[queue];
double maxP = par("dropProbability").doubleValue();
bool dropped = false;
if (minThresh <= avr && avr < maxThresh)
{
monitor->qCounters[queue] += 1;
const double pb = maxP * (avr - minThresh) / (maxThresh - minThresh);
const double pa = pb / (1 - count * pb);
const double rand = dblrand();
if (rand < pa)
{
EV << "REDDropper: rand < pa (" << rand << " < " << pa << ")" << endl;
monitor->qCounters[queue] = 0;
dropped = dropOrMark(queue);
}
}
else if (avr >= maxThresh)
{
EV << "REDDropper: Average queue length in " << qname << " exceeds the maximum threshold." << endl;
monitor->qCounters[queue] = 0;
dropped = dropOrMark(queue);
}
else if (length >= maxThresh)
{
EV << "REDDropper: Queue length in " << qname << " exceeds the maximum threshold." << endl;
monitor->qCounters[queue] = 0;
dropped = dropOrMark(queue);
}
else
{
monitor->qCounters[queue] = -1;
}
return dropped;
}