// This function is used by pthread_cond_broadcast and
// pthread_cond_signal to atomically decrement the counter
// then wake up 'counter' threads.
static int __pthread_cond_pulse(pthread_cond_t* cond, int counter) {
if (__predict_false(cond == NULL)) {
return EINVAL;
}
long flags = (cond->value & ~COND_COUNTER_MASK);
while (true) {
long old_value = cond->value;
long new_value = ((old_value - COND_COUNTER_INCREMENT) & COND_COUNTER_MASK) | flags;
if (__bionic_cmpxchg(old_value, new_value, &cond->value) == 0) {
break;
}
}
// Ensure that all memory accesses previously made by this thread are
// visible to the woken thread(s). On the other side, the "wait"
// code will issue any necessary barriers when locking the mutex.
//
// This may not strictly be necessary -- if the caller follows
// recommended practice and holds the mutex before signaling the cond
// var, the mutex ops will provide correct semantics. If they don't
// hold the mutex, they're subject to race conditions anyway.
ANDROID_MEMBAR_FULL();
__futex_wake_ex(&cond->value, COND_IS_SHARED(cond), counter);
return 0;
}
/* This function is used by pthread_cond_broadcast and
* pthread_cond_signal to atomically decrement the counter
* then wake-up 'counter' threads.
*/
static int
__pthread_cond_pulse(pthread_cond_t *cond, int counter)
{
long flags;
if (__unlikely(cond == NULL))
return EINVAL;
flags = (cond->value & ~COND_COUNTER_MASK);
for (;;) {
long oldval = cond->value;
long newval = ((oldval - COND_COUNTER_INCREMENT) & COND_COUNTER_MASK)
| flags;
if (__bionic_cmpxchg(oldval, newval, &cond->value) == 0)
break;
}
/*
* Ensure that all memory accesses previously made by this thread are
* visible to the woken thread(s). On the other side, the "wait"
* code will issue any necessary barriers when locking the mutex.
*
* This may not strictly be necessary -- if the caller follows
* recommended practice and holds the mutex before signaling the cond
* var, the mutex ops will provide correct semantics. If they don't
* hold the mutex, they're subject to race conditions anyway.
*/
ANDROID_MEMBAR_FULL();
__futex_wake_ex(&cond->value, COND_IS_SHARED(cond), counter);
return 0;
}
__LIBC_HIDDEN__
int __pthread_cond_timedwait_relative(pthread_cond_t* cond, pthread_mutex_t* mutex, const struct timespec* reltime) {
int old_value = cond->value;
pthread_mutex_unlock(mutex);
int status = __futex_wait_ex(&cond->value, COND_IS_SHARED(cond), old_value, reltime);
pthread_mutex_lock(mutex);
if (status == -ETIMEDOUT) {
return ETIMEDOUT;
}
return 0;
}
int pthread_condattr_getpshared(const pthread_condattr_t* attr, int* pshared) {
*pshared = static_cast<int>(COND_IS_SHARED(*attr));
return 0;
}
bool process_shared() {
return COND_IS_SHARED(atomic_load_explicit(&state, memory_order_relaxed));
}
