barrier.c

#define _XOPEN_SOURCE 600
#include <pthread.h>
#include <stdio.h>

pthread_barrier_t barrier;
#define NUM_THREADS 5

void *thread_routine(void *arg)
{
  int thd_id = (int) arg;
  int rc;
  printf("thd %d: before teh barrier\n", thd_id);

  // toate firele de executie asteapta la bariera.
  rc = pthread_barrier_wait(&barrier);
  if (rc == PTHREAD_BARRIER_SERIAL_THREAD) {
    // un singur fir de execuie (posibil ultimul) va intoarce PTHREAD_BARRIER_SERIAL_THREAD
    // restul firelor de execuie întorc 0 în caz de succes.
    printf("thd %d let the flood in\n", thd_id);
  }
  printf("thd %d: after the barrier\n", thd_id);
  return NULL;
}

int main()
{
  int i;
  pthread_t tids[NUM_THREADS];

  // bariera este initializata o singura data si folosita de toate firele de executie
  pthread_barrier_init(&barrier, NULL, NUM_THREADS);

  // firele de executie vor executa codul functiei 'thread_routine'
  // in locul unui pointer la date utile, se trimite in ultimul argument
  // un intreg - identificatorul firului de executie
  for (i = 0; i < NUM_THREADS; i++)
    pthread_create(&tids[i], NULL, thread_routine, (void *) i);

  // asteptam ca toate firele de executie sa se termine
  for (i = 0; i < NUM_THREADS; i++)
    pthread_join(tids[i], NULL);

  // eliberam resursele barierei
  pthread_barrier_destroy(&barrier);
  return 0;
}