Paul Irofti wrote:
> > What do you think?
>
> I think this diff is even safer: it checks for threads entering and
> exiting the barrier while holding the mutex, and if both values are 0 it
> proceeds to destroy the barrier.
>
> I also renamed sofar to in so that the relationship between threads is
> more obvious.
where did this go?
>
>
> Index: rthread.h
> ===================================================================
> RCS file: /cvs/src/lib/librthread/rthread.h,v
> retrieving revision 1.55
> diff -u -p -r1.55 rthread.h
> --- rthread.h 27 Jan 2016 08:40:05 -0000 1.55
> +++ rthread.h 16 Mar 2016 12:36:39 -0000
> @@ -141,7 +141,8 @@ struct pthread_barrier {
> pthread_mutex_t mutex;
> pthread_cond_t cond;
> int threshold;
> - int sofar;
> + int in;
> + int out;
> int generation;
> };
>
> Index: rthread_barrier.c
> ===================================================================
> RCS file: /cvs/src/lib/librthread/rthread_barrier.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 rthread_barrier.c
> --- rthread_barrier.c 23 Apr 2012 08:30:33 -0000 1.2
> +++ rthread_barrier.c 16 Mar 2016 12:36:39 -0000
> @@ -74,12 +74,18 @@ pthread_barrier_destroy(pthread_barrier_
> if (barrier == NULL || *barrier == NULL)
> return (EINVAL);
>
> + if (pthread_mutex_trylock(&(*barrier)->mutex))
> + return (EBUSY);
> +
> b = *barrier;
>
> - if (b->sofar > 0)
> + if (b->out > 0 || b->in > 0) {
> + pthread_mutex_unlock(&b->mutex);
> return (EBUSY);
> + }
>
> *barrier = NULL;
> + pthread_mutex_unlock(&b->mutex);
> pthread_mutex_destroy(&b->mutex);
> pthread_cond_destroy(&b->cond);
> free(b);
> @@ -103,9 +109,10 @@ pthread_barrier_wait(pthread_barrier_t *
> if ((rc = pthread_mutex_lock(&b->mutex)))
> goto cancel;
>
> - _rthread_debug(6, "sofar: %d, threshold: %d\n", b->sofar, b->threshold);
> - if (++b->sofar == b->threshold) {
> - b->sofar = 0;
> + _rthread_debug(6, "in: %d, threshold: %d\n", b->in, b->threshold);
> + if (++b->in == b->threshold) {
> + b->out = b->in - 1; /* mark thread exit */
> + b->in = 0;
> b->generation++;
> if ((rc = pthread_cond_broadcast(&b->cond)))
> goto err;
> @@ -118,6 +125,7 @@ pthread_barrier_wait(pthread_barrier_t *
> if ((rc = pthread_cond_wait(&b->cond, &b->mutex)))
> goto err;
> } while (gen == b->generation);
> + b->out--; /* mark thread exit */
> }
>
> err:
>
