/* ------------------------------------------------------------------------- * This program simulates a single-server FIFO service node using arrival * times and service times read from a text file.  The server is assumed * to be idle when the first job arrives.  All jobs are processed completely * so that the server is again idle at the end of the simulation.   The * output statistics are the average interarrival time, average service * time, the average delay in the queue, and the average wait in the service  * node.  * * Name              : ssq1.c  (Single Server Queue, version 1) * Authors           : Steve Park & Dave Geyer * Language          : ANSI C * Latest Revision   : 9-01-98 * Compile with      : gcc ssq1.c  * -------------------------------------------------------------------------  */#include <stdio.h>                              #define FILENAME   "ssq1.dat"                  /* input data file */#define START      0.0/* =========================== */   double GetArrival(FILE *fp)                 /* read an arrival time *//* =========================== */{   double a;  fscanf(fp, "%lf", &a);  return (a);}/* =========================== */   double GetService(FILE *fp)                 /* read a service time *//* =========================== */{   double s;  fscanf(fp, "%lf\n", &s);  return (s);}/* ============== */   int main(void)/* ============== */{  FILE   *fp;                                  /* input data file      */  long   index     = 0;                        /* job index            */  double arrival   = START;                    /* arrival time         */  double delay;                                /* delay in queue       */  double service;                              /* service time         */  double wait;                                 /* delay + service      */  double departure = START;                    /* departure time       */  struct {                                     /* sum of ...           */    double delay;                              /*   delay times        */    double wait;                               /*   wait times         */    double service;                            /*   service times      */    double interarrival;                       /*   interarrival times */  } sum = {0.0, 0.0, 0.0};  fp = fopen(FILENAME, "r");  if (fp == NULL) {    fprintf(stderr, "Cannot open input file %s\n", FILENAME);    return (1);  }  while (!feof(fp)) {    index++;    arrival      = GetArrival(fp);    if (arrival < departure)       delay      = departure - arrival;        /* delay in queue    */    else       delay      = 0.0;                        /* no delay          */    service      = GetService(fp);    wait         = delay + service;    departure    = arrival + wait;             /* time of departure */    sum.delay   += delay;    sum.wait    += wait;    sum.service += service;  }  sum.interarrival = arrival - START;  printf("\nfor %ld jobs\n", index);  printf("   average interarrival time = %6.2f\n", sum.interarrival / index);  printf("   average service time .... = %6.2f\n", sum.service / index);  printf("   average delay ........... = %6.2f\n", sum.delay / index);  printf("   average wait ............ = %6.2f\n", sum.wait / index);  fclose(fp);  return (0);}