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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "config.h"
#include "runtime.h"
#include <errno.h>
#include <stdlib.h>
#include <time.h>
#include <semaphore.h>
/* If we don't have sem_timedwait, use pthread_cond_timedwait instead.
We don't always use condition variables because on some systems
pthread_mutex_lock and pthread_mutex_unlock must be called by the
same thread. That is never true of semaphores. */
struct go_sem
{
sem_t sem;
#ifndef HAVE_SEM_TIMEDWAIT
int timedwait;
pthread_mutex_t mutex;
pthread_cond_t cond;
#endif
};
/* Create a semaphore. */
uintptr
runtime_semacreate(void)
{
struct go_sem *p;
/* Call malloc rather than runtime_malloc. This will allocate space
on the C heap. We can't call runtime_malloc here because it
could cause a deadlock. */
p = malloc (sizeof (struct go_sem));
if (sem_init (&p->sem, 0, 0) != 0)
runtime_throw ("sem_init");
#ifndef HAVE_SEM_TIMEDWAIT
if (pthread_mutex_init (&p->mutex, NULL) != 0)
runtime_throw ("pthread_mutex_init");
if (pthread_cond_init (&p->cond, NULL) != 0)
runtime_throw ("pthread_cond_init");
#endif
return (uintptr) p;
}
/* Acquire m->waitsema. */
int32
runtime_semasleep (int64 ns)
{
M *m;
struct go_sem *sem;
int r;
m = runtime_m ();
sem = (struct go_sem *) m->waitsema;
if (ns >= 0)
{
int64 abs;
struct timespec ts;
int err;
abs = ns + runtime_nanotime ();
ts.tv_sec = abs / 1000000000LL;
ts.tv_nsec = abs % 1000000000LL;
err = 0;
#ifdef HAVE_SEM_TIMEDWAIT
r = sem_timedwait (&sem->sem, &ts);
if (r != 0)
err = errno;
#else
if (pthread_mutex_lock (&sem->mutex) != 0)
runtime_throw ("pthread_mutex_lock");
while ((r = sem_trywait (&sem->sem)) != 0)
{
r = pthread_cond_timedwait (&sem->cond, &sem->mutex, &ts);
if (r != 0)
{
err = r;
break;
}
}
if (pthread_mutex_unlock (&sem->mutex) != 0)
runtime_throw ("pthread_mutex_unlock");
#endif
if (err != 0)
{
if (err == ETIMEDOUT || err == EAGAIN || err == EINTR)
return -1;
runtime_throw ("sema_timedwait");
}
return 0;
}
while (sem_wait (&sem->sem) != 0)
{
if (errno == EINTR)
continue;
runtime_throw ("sem_wait");
}
return 0;
}
/* Wake up mp->waitsema. */
void
runtime_semawakeup (M *mp)
{
struct go_sem *sem;
sem = (struct go_sem *) mp->waitsema;
if (sem_post (&sem->sem) != 0)
runtime_throw ("sem_post");
#ifndef HAVE_SEM_TIMEDWAIT
if (pthread_mutex_lock (&sem->mutex) != 0)
runtime_throw ("pthread_mutex_lock");
if (pthread_cond_broadcast (&sem->cond) != 0)
runtime_throw ("pthread_cond_broadcast");
if (pthread_mutex_unlock (&sem->mutex) != 0)
runtime_throw ("pthread_mutex_unlock");
#endif
}
void
runtime_osinit (void)
{
}
void
runtime_goenvs (void)
{
runtime_goenvs_unix ();
}
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