The files in this directory originally come from https://github.com/percona/PerconaFT/. This directory only includes the "locktree" part of PerconaFT, and its dependencies. The following modifications were made: - Make locktree usable outside of PerconaFT library - Add shared read-only lock support The files named *_subst.* are substitutes of the PerconaFT's files, they contain replacements of PerconaFT's functionality.