#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <pthread.h>

static int num_ops;
static pthread_t *thr_array;


static void *
thr_main(void *arg)
{
  int i;
  int sum = 0;

  for (i = 0; i < num_ops; i++) {
    sum += i;
  }

  return (void *)(intptr_t)sum;
}

static void
spawn_thread(int thr)
{
  int ret;

  ret = pthread_create(&thr_array[thr], NULL, thr_main, NULL);
  if (ret != 0) {
    fprintf(stderr, "pthread_create: %s\n", strerror(ret));
    exit(1);
  }
}

static void
join_thread(int thr)
{
  int ret;

  ret = pthread_join(thr_array[thr], NULL);
  if (ret != 0) {
    fprintf(stderr, "pthread_join: %s\n", strerror(ret));
    exit(1);
  }
}

int
main(int argc, char *argv[])
{
  int num_spawns;
  int num_threads;
  int thr;
  int thr_saved;
  int ret;
  int spawn_count;

  if (argc != 4) {
    fprintf(stderr, "Usage: oprofile_multithread_test <number of spawns> <number of threads> <number of operations per thread>\n");
    exit(1);
  }

  num_spawns = atoi(argv[1]);
  num_threads = atoi(argv[2]);
  num_ops = atoi(argv[3]);
  if (num_threads < 1) {
    fprintf(stderr, "Number of threads must be positive.\n");
    exit(1);
  }

  thr_array = malloc(sizeof(pthread_t) * num_threads);
  if (thr_array == NULL) {
    fprintf(stderr, "Cannot allocate thr_array\n");
    exit(1);
  }

  spawn_count = 0;
  for (thr = 0; thr < num_threads; thr++) {
    spawn_thread(thr);
    spawn_count++;
  }

  thr = 0;
  while  (num_spawns < 0 ? 1 /* infinite loop */ : spawn_count < num_spawns) {
    join_thread(thr);
    spawn_thread(thr);
    thr = (thr + 1) % num_threads;
    spawn_count++;
  }

  thr_saved = thr;
  do {
    join_thread(thr);
    thr = (thr + 1) % num_threads;    
  } while (thr != thr_saved);

  free(thr_array);
}