Method stop_wait

kernel/oswrapper/vspace.h:1173–1181

template <typename T>
void SyncVar<T>::stop_wait() {
  _lock.lock();
  if (!_sem.is_null()) {
    _sem->stop_wait();
    if (!_sem->_idle())
      _sem->post();
  }
  _lock.unlock();
}

template <typename T>
T SyncVar<T>::read() {