/**
* Copyright (C) 2006, Laboratorio di Valutazione delle Prestazioni - Politecnico di Milano
* 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 2 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* Created on 11-mar-2004
*
*/
package jmt.jmarkov.Queues;
import java.util.Random;
import jmt.jmarkov.Queues.Exceptions.NoJobsException;
import jmt.jmarkov.Queues.Exceptions.NonErgodicException;
/**
* Contains the algorithm of the queue M/M/1 where lambda represent the arrival of the job
* in second and s as service time of the job in the processor.
* M/M/1 is the poisson process of arrival and service time.
*
*/
public class MM1Logic implements QueueLogic {
/**
* arrival rate [job/ms]
*/
protected double lambda;
/**
* service time in the processor[ms]
*/
protected double s;
/**
* random number generator
*/
protected Random rnd;
/**
* Initialize the queue
* @param lambda represent the medium of arrival of <i>Poisson process</i> <b>[job/s]</b>
* @param s represent the medium of the service time of <i>Poisson process</i> <b>[ms]</b>
*/
public MM1Logic(double lambda, double s) {
this.lambda = lambda;
this.s = s;
rnd = new Random();
}
/* (non-Javadoc)
* @see Queues.QueueLogic#getArrivalTime()
*/
public double getArrivalTime() throws NoJobsException {
if (lambda == 0) {
throw new NoJobsException();
}
return (this.getTime(1000.0 / lambda));
}
/* (non-Javadoc)
* @see Queues.QueueLogic#getRunTime()
*/
public double getRunTime() {
return (this.getTime(s * 1000.0));
}
/* (non-Javadoc)
* @see Queues.QueueLogic#getStatusProbability(int)
*/
public double getStatusProbability(int status) throws NonErgodicException {
return ((1 - utilization()) * Math.pow(utilization(), status));
}
/**
* Calculate the interarrival time of poisson distribution with given medium
*/
private double getTime(double media) {
//forma esplicita della legge di distribuzione Poisson
return ((-media * Math.log(rnd.nextDouble())));
}
/**
* setting the value of <b>lambda</b>
* @param lambda new value <b>[job/s]</b>
*/
public void setLambda(double lambda) {
this.lambda = lambda;
}
/**
* setting the value of <b>s</b>
* @param s new value <b>[s]</b>
*/
public void setS(double s) {
this.s = s;
}
/**
* Calculate the average jobs in the station
* with respect to lambda and s
*
* @return number of average jobs in the station
*
* @exception NonErgodicException queue is not ergodic (U > 1 o U < 0)
*/
public double mediaJobs() throws NonErgodicException {
return (utilization()) / (1.0 - utilization());
}
/**
* Calculate the utilizaion of the server
* with respect to parameters lambda and s
*
* @return utilization
*
* @exception NonErgodicException queue is not ergodic (U > 1 o U < 0)
*/
public double utilization() throws NonErgodicException {
if ((lambda * s) > 1) {
throw new NonErgodicException();
} else {
return (lambda * s);
}
}
/* (non-Javadoc)
* @see Queues.QueueLogic#getMaxStates()
*/
public int getMaxStates() {
return 0;
}
/**
* @param buffer
*/
public void setMaxStates(int buffer) {
// the maximum queue length is infinite
}
/* (non-Javadoc)
* @see Queues.QueueLogic#throughput()
*/
public double throughput() throws NonErgodicException {
return mediaJobs() / responseTime();
}
/* (non-Javadoc)
* @see Queues.QueueLogic#responseTime()
*/
public double responseTime() throws NonErgodicException {
return s / (1.0 - utilization());
}
public double getLambda() {
return lambda;
}
public double getS() {
return s;
}
public int getNumberServer() {
return 1;
}
}