Making ROS TF Transactional

TF library is a frequently used package in ROS, which manages transformations between coordinate systems as a directed tree structure, and enables registrations and calculation of coordinate transformation information. TF tree access is not scalable due to a giant lock and does not provide the latest data. The proposed method solves these problems by applying the fine-grained locking method and the two phase locing. We show that the proposed method achieves up to 143 times faster throughput, up to 208 times shorter latency, and up to 132 times data freshness than the existing methods.