barrier.h

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#ifndef BARRIER_H
#define BARRIER_H
 
#include <pthread.h>            /* pthread_* */
#include "../config.h"          /* HAVE_PTHREAD_BARRIER_WAIT */
 
#ifndef HAVE_PTHREAD_BARRIER_WAIT /* If POSIX BARRIERS are not supported */
 
#define pthread_barrier_t           barrier_t
#define pthread_barrier_attr_t      barrier_attr_t
#define pthread_barrier_init(b,a,n) barrier_init(b,n)
#define pthread_barrier_destroy(b)  barrier_destroy(b)
#define pthread_barrier_wait(b)     barrier_wait(b)
 
#define PTHREAD_BARRIER_SERIAL_THREAD 1
#define BARRIER_ARRIVE(B,RV)                            \
    RV = pthread_barrier_wait(B);                       \
    if(RV !=0 && RV != PTHREAD_BARRIER_SERIAL_THREAD){  \
        printf("Couldn't wait on barrier\n");           \
        exit(EXIT_FAILURE);                             \
    }
 
typedef struct {
    int             needed;
    int             called;
    pthread_mutex_t mutex;
    pthread_cond_t  cond;
} barrier_t;
 
static int barrier_init(barrier_t *barrier,int needed);
static int barrier_destroy(barrier_t *barrier);
static int barrier_wait(barrier_t *barrier);
 
int 
barrier_init(barrier_t *barrier,int needed)
{
    barrier->needed = needed;
    barrier->called = 0;
    pthread_mutex_init(&barrier->mutex,NULL);
    pthread_cond_init(&barrier->cond,NULL);
 
    return 0;
}
 
int 
barrier_destroy(barrier_t *barrier)
{
    pthread_mutex_destroy(&barrier->mutex);
    pthread_cond_destroy(&barrier->cond);
 
    return 0;
}
 
int 
barrier_wait(barrier_t *barrier)
{
    pthread_mutex_lock(&barrier->mutex);
    barrier->called++;
 
    if (barrier->called == barrier->needed) {
        barrier->called = 0;
        pthread_cond_broadcast(&barrier->cond);
    } else {
        pthread_cond_wait(&barrier->cond,&barrier->mutex);
    }
 
    pthread_mutex_unlock(&barrier->mutex);
 
    return 0;
}
 
#endif
 
#endif /* BARRIER_H */