Method pop

pose_graph/include/utils/ThreadSafeQueue.h:365–374

template <typename T>
bool ThreadsafeQueue<T>::pop(T& value) {
  if (shutdown_) return false;
  std::unique_lock<std::mutex> lk(mutex_);
  if (data_queue_.empty()) return false;
  value = std::move(*data_queue_.front());
  data_queue_.pop();
  lk.unlock();  // Unlock before notify.
  data_cond_.notify_one();
  return true;
}

template <typename T>
std::shared_ptr<T> ThreadsafeQueue<T>::pop() {