//================================================== file = measureUtil.c =====
//=  A CSIM simulation of an M/D/1 with explicit utilization measurement      =
//=============================================================================
//=  Notes: 1) Values for lambda and mu are set in the main program           =
//=         2) Determines utilization in three different ways                 =
//=---------------------------------------------------------------------------=
//= Example execution:                                                        =
//=                                                                           =
//=  *** BEGIN SIMULATION ***                                                 =
//=  =============================================================            =
//=  ==     *** CSIM M/D/1 queueing system simulation ***       ==            =
//=  =============================================================            =
//=  = Lambda   = 1.000000 cust/sec                                           =
//=  = Mu       = 3.000000 cust/sec                                           =
//=  =============================================================            =
//=  = Total CPU time     = 0.967000 sec                                      =
//=  = Total sim time     = 1000000.000000 sec                                =
//=  = Total completions  = 1001211 cust                                      =
//=  =------------------------------------------------------------            =
//=  = >>> Simulation results                                    -            =
//=  =------------------------------------------------------------            =
//=  = Utilization #1     = 33.333333 %                                       =
//=  = Utilization #2     = 33.373700 %                                       =
//=  = Utilization #3     = 33.373700 %                                       =
//=  = Mean num in system = 0.417360 cust                                     =
//=  = Mean response time = 0.416855 sec                                      =
//=  = Mean service time  = 0.333333 sec                                      =
//=  = Mean throughput    = 1.001211 cust/sec                                 =
//=  =============================================================            =
//=  *** END SIMULATION ***                                                   =
//=---------------------------------------------------------------------------=
//=  Build: standard CSIM build                                               =
//=---------------------------------------------------------------------------=
//=  Execute: measureUtil                                                     =
//=---------------------------------------------------------------------------=
//=  Author: Ken Christensen                                                  =
//=          University of South Florida                                      =
//=          WWW: http://www.csee.usf.edu/~christen                           =
//=          Email: christen@csee.usf.edu                                     =
//=---------------------------------------------------------------------------=
//=  History: KJC (07/01/13) - Genesis (from mm1_csim.c)                      =
//=============================================================================
//----- Includes --------------------------------------------------------------
#include <stdio.h>      // Needed for printf()
#include "csim.h"       // Needed for CSIM stuff

//----- Defines ---------------------------------------------------------------
#define SIM_TIME 1.0e6  // Total simulation time in seconds

//----- Globals ---------------------------------------------------------------
FACILITY Server;        // Declaration of CSIM Server facility
int      DepartCount;   // Departures counter

//----- Prototypes ------------------------------------------------------------
void generate(double lambda, double mu);  // Customer generator
void queue1(double service_time);         // Single server queue

//=============================================================================
//==  Main program                                                           ==
//=============================================================================
void sim(void)
{
  double   lambda;      // Mean arrival rate (cust/sec)
  double   mu;          // Mean service rate (cust/sec)
  double   util1;       // Utilization #1
  double   util2;       // Utilization #2
  double   util3;       // Utilization #3

  // Create the simulation
  create("sim");

  // CSIM and variable initializations
  Server = facility("Server");
  DepartCount = 0;

  // Parameter initializations
  lambda = 1.0;
  mu = 3.0;

  // Output begin-of-simulation banner
  printf("*** BEGIN SIMULATION *** \n");

  // Initiate generate function and hold for SIM_TIME
  generate(lambda, mu);
  hold(SIM_TIME);

  // Compute the utilization in three ways
  util1 = lambda / mu;
  util2 = util(Server);
  util3 = DepartCount * (1.0 / mu) / clock;

  // Output results
  printf("============================================================= \n");
  printf("==     *** CSIM M/D/1 queueing system simulation ***       == \n");
  printf("============================================================= \n");
  printf("= Lambda   = %f cust/sec   \n", lambda);
  printf("= Mu       = %f cust/sec   \n", mu);
  printf("============================================================= \n");
  printf("= Total CPU time     = %f sec      \n", cputime());
  printf("= Total sim time     = %f sec      \n", clock);
  printf("= Total completions  = %d cust     \n", completions(Server));
  printf("=------------------------------------------------------------ \n");
  printf("= >>> Simulation results                                    - \n");
  printf("=------------------------------------------------------------ \n");
  printf("= Utilization #1     = %f %%       \n", 100.0 * util1);
  printf("= Utilization #2     = %f %%       \n", 100.0 * util2);
  printf("= Utilization #3     = %f %%       \n", 100.0 * util3);
  printf("= Mean num in system = %f cust     \n", qlen(Server));
  printf("= Mean response time = %f sec      \n", resp(Server));
  printf("= Mean service time  = %f sec      \n", serv(Server));
  printf("= Mean throughput    = %f cust/sec \n", tput(Server));
  printf("============================================================= \n");

  // Output end-of-simulation banner
  printf("*** END SIMULATION *** \n");
}

//=============================================================================
//==  Function to generate Poisson customers                                 ==
//=============================================================================
void generate(double lambda, double mu)
{
  double   interarrival_time;    // Interarrival time to next send
  double   service_time;         // Service time for this customer

  create("generate");

  // Loop forever to create customers
  while(1)
  {
    // Pull an interarrival time and hold for it
    interarrival_time = exponential(1.0 / lambda);
    hold(interarrival_time);

    // Pull a service time and then send the customer to the queue
    service_time = 1.0 / mu;
    queue1(service_time);
  }
}

//=============================================================================
//==  Function for single server queue                                       ==
//=============================================================================
void queue1(double service_time)
{
  create("queue1");

  // Reserve, hold, and release server
  reserve(Server);
  hold(service_time);
  release(Server);

  // Increment the departure counter
  DepartCount++;
}