/* ------------------------------------------------------------------------- * This program - an extension of program ssq1.c - simulates a single-server * FIFO service node using Exponentially distributed interarrival times and * Uniformly distributed service times (i.e. a M/U/1 queue). * * Name              : Ssq2.java  (Single Server Queue, version 2) * Authors           : Steve Park & Dave Geyer * Translated by     : Jun Wang & Richard Dutton * Language          : Java * Latest Revision   : 6-16-06 * -------------------------------------------------------------------------  */import java.io.*;import java.lang.*;import java.text.*;class Ssq2Sum {                                  /* sum of ...           */  double delay;                                  /*   delay times        */  double wait;                                   /*   wait times         */  double service;                                /*   service times      */  double interarrival;                           /*   interarrival times */  void initSumParas() {    delay = 0.0;    wait = 0.0;    service = 0.0;    interarrival = 0.0;  }}class Ssq2 {  static long LAST = 10000;                    /* number of jobs processed */  static double START = 0.0;                   /* initial time             */    static double sarrival = START;              /* Why did I do this?       */  public static void main(String[] args) {        long   index     = 0;                         /* job index            */    double arrival   = START;                     /* time of arrival      */    double delay;                                 /* delay in queue       */    double service;                               /* service time         */    double wait;                                  /* delay + service      */    double departure = START;                     /* time of departure    */    Ssq2Sum sum = new Ssq2Sum();    sum.initSumParas();          Ssq2 s = new Ssq2();    Rng r = new Rng();    r.putSeed(123456789);    while (index < LAST) {      index++;      arrival      = s.getArrival(r);      if (arrival < departure)        delay      = departure - arrival;         /* delay in queue    */      else        delay      = 0.0;                         /* no delay          */      service      = s.getService(r);      wait         = delay + service;      departure    = arrival + wait;              /* time of departure */      sum.delay   += delay;      sum.wait    += wait;      sum.service += service;    }    sum.interarrival = arrival - START;    DecimalFormat f = new DecimalFormat("###0.00");    System.out.println("\nfor " + index + " jobs");    System.out.println("   average interarrival time =   " + f.format(sum.interarrival / index));    System.out.println("   average wait ............ =   " + f.format(sum.wait / index));    System.out.println("   average delay ........... =   " + f.format(sum.delay / index));    System.out.println("   average service time .... =   " + f.format(sum.service / index));    System.out.println("   average # in the node ... =   " + f.format(sum.wait / departure));    System.out.println("   average # in the queue .. =   " + f.format(sum.delay / departure));    System.out.println("   utilization ............. =   " + f.format(sum.service / departure));  }   static double exponential(double m, Rng r) {/* --------------------------------------------------- * generate an Exponential random variate, use m > 0.0 * --------------------------------------------------- */    return (-m * Math.log(1.0 - r.random()));  }   double uniform(double a, double b, Rng r) {/* ------------------------------------------------ * generate an Uniform random variate, use a < b * ------------------------------------------------ */    return (a + (b - a) * r.random());  }   static double getArrival(Rng r) {/* ------------------------------ * generate the next arrival time * ------------------------------ *///    static double sarrival = START;    sarrival += exponential(2.0, r);    return (sarrival);  }   double getService(Rng r) {/* ------------------------------ * generate the next service time * ------------------------------ */    return (uniform(1.0, 2.0, r));  }    }