/*
  Test how much time is needed for a process/thread creation
  Author: Gergely Czuczy <phoemix@harmless.hu>
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>


double timeval2double(struct timeval *_tv);
void *threadfunc(void *);

/*
  ================================
  int main(int argc, char *argv[])
  ================================
 */
int main(int argc, char *argv[]) {
  unsigned int i;
  unsigned int samples;
  unsigned int forkfailures(0), threadfailures(0);
  double totalforktime(0),totalthreadtime(0), forktime, threadtime;
  struct timeval begin,end,diff;
  pid_t childpid;
  pthread_t thread;

  if ( argc != 2 ) {
    printf("Usage:\n\t%s <number of samples>\n", argv[0]);
    return EXIT_FAILURE;
  }

  // we get the number of samples to take
  samples = atoi(argv[1]);

  // test the forks
  printf("\n");
  for ( i=0; i<samples; ++i ) {
    printf("\rFork test: %u/%u (%3.2f%%)", i+1, samples, ((i+1.0)/samples)*100);fflush(0);

    gettimeofday(&begin, 0);
    childpid = fork();
    gettimeofday(&end, 0);

    if ( !childpid ) _exit(0);
    if ( childpid==-1 ) ++forkfailures;

    timersub(&end, &begin, &diff);
    totalforktime += timeval2double(&diff);
    usleep(1);
  }
  printf("\n");

  usleep(10000);

  // test the threads
  printf("\n");
  for ( i=0; i<samples; ++i ) {
    int ret;

    printf("\rThread test: %u/%u (%3.2f%%)", i+1, samples, ((i+1.0)/samples)*100);fflush(0);

    gettimeofday(&begin, 0);
    ret = pthread_create(&thread, 0, &threadfunc, 0);
    gettimeofday(&end, 0);

    if ( ret ) ++threadfailures;

    timersub(&end, &begin, &diff);
    totalthreadtime += timeval2double(&diff);
    usleep(1);
  }
  printf("\n\n");


  // print the results
  forktime = totalforktime / (samples-forkfailures);
  printf("Fork failures: %u (succes: %u)\n", forkfailures, samples-forkfailures);
  printf("Avarage fork time: %5f msecs\n", forktime);
  printf("Total fork time: %5f msecs\n", totalforktime);
  threadtime = totalthreadtime / (samples-threadfailures);
  printf("Thread failures: %u (success: %u)\n", threadfailures, samples-threadfailures);
  printf("Avarage thread time: %5f msecs\n", threadtime);
  printf("Total thread time: %5f msecs\n", totalthreadtime);
  printf("Avarage fork/thread ratio: %2f\n", forktime/threadtime);
  printf("Total fork/thread ratio: %2f\n", totalforktime/totalthreadtime);

  return EXIT_SUCCESS;
}

/*
  ============================
  void *threadfunc(void *_arg)
  ============================
 */
void *threadfunc(void *) {
  pthread_exit(0);
  return 0;
}

/*
  ==========================================
  double timeval2double(struct timeval *_tv)
  ==========================================
 */
double timeval2double(struct timeval *_tv) {
  double ret;
  ret = _tv->tv_usec;
  ret /= 1000000;
  ret += _tv->tv_sec;
  ret *= 1000;
  return ret;
}