Method try_enqueue

kernel/oswrapper/vspace.h:1115–1122

    enqueue_nowait(item);
  }
  bool try_enqueue(T item) {
    if (_bounded && _outgoing.try_wait()) {
      enqueue_nowait(item);
      return true;
    } else {
      return false;
    }
  }
  T dequeue() {
    _incoming.wait();
    return dequeue_nowait();