011fc8be2d
Summary: Adding some stats that would be helpful to monitor if the DB has gone to unlikely stats that would hurt the performance. These are mostly when we end up needing to acquire a mutex. Closes https://github.com/facebook/rocksdb/pull/3683 Differential Revision: D7529393 Pulled By: maysamyabandeh fbshipit-source-id: f7d36279a8f39bd84d8ddbf64b5c97f670c5d6d9