/*
 * compteurBOOM_v3_N_threads_mutex.c
 *
 * Version multithread utilisant un mutex pour protéger les accès à counter.
 */

#include <error.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <assert.h>

#define FINAL_COUNTER 200000000
#define NB_THREAD 8

int counter = 0;

pthread_mutex_t lock;

void *start_routine(void *arg) {
  int i;

  for (i = 0; i < FINAL_COUNTER / NB_THREAD; i++) {
    pthread_mutex_lock(&lock); // Prend le verrou
    counter ++;
    pthread_mutex_unlock(&lock); // Libère le verrou
  }
  pthread_exit(NULL);
}

int main (int argc, char *argv[]) {
  int rc;
  pthread_t thread[NB_THREAD];
  
  assert(FINAL_COUNTER % NB_THREAD == 0); // Pour verifier que, si on repartit le travail d'incrementation de counter entre NB_THREAD, on est certain d'obtenir FINAL_COUNTER.

  pthread_mutex_init(&lock, NULL); // Initialise le verrou

  for (int i = 0; i < NB_THREAD; i++) {
    rc = pthread_create(&thread[i], NULL, start_routine, NULL);
    if (rc)
      error(EXIT_FAILURE, rc, "pthread_create");
  }
  
  for (int i = 0; i < NB_THREAD; i++) {
    rc = pthread_join(thread[i], NULL);
    if (rc)
      error(EXIT_FAILURE, rc, "pthread_join");
  }

  if (counter != FINAL_COUNTER)
    printf("BOOM! counter = %d\n", counter);
  else
    printf("OK counter = %d\n", counter);

  pthread_mutex_destroy(&lock); // Detruit le verrou
  exit(EXIT_SUCCESS);
}