PoissonTrafficSource.cpp

/*
 * Copyright (C) 2015 Miguel Rodríguez Pérez <miguel@det.uvigo.es>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "PoissonTrafficSource.h"

#include "Grid.h"
#include "Event.h"

#include <random>

using namespace std;

namespace {

    class PoissonTrafficSourceEvent : public Event {
    public:

        PoissonTrafficSourceEvent(const PoissonTrafficSource& poisson_source, Node::nodeid_t src, Node::nodeid_t dst, Event::evtime_t dispatch_time) : Event(dispatch_time), poisson_traffic_source_(poisson_source), src_(src), dst(dst) {            
        }

        virtual void process() {
            newEvent(poisson_traffic_source_.sendPacket(src_, dst, getDispatchTime()));
        }

#ifndef NDEBUG

        virtual ostream& dump(ostream& os) const {
            Event::dump(os);

            os << "Kind: PoissonTraffic " << " Src: " << src_ << " Dst: " << dst << ' ';

            return os;
        }
#endif

    private:
        const PoissonTrafficSource& poisson_traffic_source_;
        const Node::nodeid_t src_, dst;
    };
}

PoissonTrafficSource::PoissonTrafficSource(const Grid& grid, double rate) : TrafficSource(grid), rate_(rate) {
    auto nodes = grid.countDeployedNodes();

    for (unsigned i = 2; i <= nodes; i++) {// The first node does not send traffic        
        Calendar::getCalendar().newEvent(make_unique<PoissonTrafficSourceEvent>(*this, i, 1, getTimeToNextPacket()));
    }
}

Event::evtime_t PoissonTrafficSource::getTimeToNextPacket() const {
    exponential_distribution<Event::evtime_t> exp_distr(rate_);
    
    return exp_distr(Calendar::getCalendar().getRandomGenerator());
}

unique_ptr<Event> PoissonTrafficSource::sendPacket(Node::nodeid_t src, Node::nodeid_t dst, Event::evtime_t now) const {
    Node& src_node = getGrid().getNodeById(src);

    src_node.Route(Packet(src, dst, getGrid().getNodeLocation(dst), now), now);
    return make_unique<PoissonTrafficSourceEvent>(*this, src, dst, now + getTimeToNextPacket());   
}