/* this program is to simulate a homogenerous parallel fork join queueing system */

#include "cpp.h"

#define MAX_NUM_SERVER       20


facility_set   server ("server", MAX_NUM_SERVER);
event      global_done ("global_done");
table      response_time_tbl("rt_tbl"); /* store average response time of job */
int        num_server;        /* number of parallel servers */
int        total_job;         /* number of job to simulate */
long int   N=0;               /* total number of job completed */
float      arrival_rate;      /* job arrrival rate */
float      service_rate;      /* each task's service rate */


void input();
void generate_job();
void job();
void task(int i, event *ev);

extern "C" void sim(int, char **);

void sim(int argc, char *argv[])
{

     int  m_e, m_p;

     set_model_name("fork_join");
     create("sim");

     m_e = max_events(5000);
     m_p = max_processes(5000);

     input();                 /* input information */
     generate_job();          /* create job */
     global_done.wait();
     report();


}

void input()
{

     printf("input number of parallel servers\n");
     scanf("%d", &num_server);
     printf("input job arrival rate and task service rate\n");
     scanf("%f %f", &arrival_rate, &service_rate);
     printf("input total number of jobs to simulate:\n");
     scanf("%d", &total_job);

     if (num_server >  MAX_NUM_SERVER){
       printf("num_server > MAXIMUM allowed\n");
       exit(0);
     }

     if (num_server <  1){
       printf("num_server should be >= 2\n");
       exit(1);
     }
}




void generate_job()
{

     int i;
     float rate;

     create("gen_job");

     for (i=1; i <= total_job + 50; i++) {
          hold(expntl(1.0/arrival_rate));
          job();
     }
}


void job()
{

     double t1;
     int    i, count;
         
     create("job");

     event task_done_event("task_done"); /* create event for task synchronization */
     count = 0;

     t1 = clock;             

     for (i=0; i < num_server;  i++)  /* fork tasks */
        task(i, &task_done_event);
     

     while (count != num_server) { /* wait for all task to complete */
         task_done_event.clear();
         task_done_event.wait();
         count++;
     }

     /* job is done */
     response_time_tbl.record(clock - t1);
     N++;
     if ( N == total_job)   /* tell sim() the end of simulation */
        global_done.set();

}



void task(int i, event *task_done_event)
{
    

     create("task");

     server[i].reserve() ;   /* task is assigned to server i */   
        hold (expntl(1.0/service_rate));
     server[i].release();
     task_done_event->set();
}