US Patent 11379324 Persistent memory transactions with undo logging

Undo logging for persistent memory transactions may permit concurrent transactions to write to the same persistent object. After an undo log record has been written, a single persist barrier may be issued. The tail pointer of the undo log may be updated after the persist barrier, and without another persist barrier, so the tail update may be persisted when the next log record is written and persisted. Undo logging for persistent memory transactions may rely on inferring the tail of an undo log after a failure rather than relying on a guaranteed correct tail pointer based on persisting the tail after every append. Additionally, transaction version numbers and checksum information may be stored to the undo log enabling failure recovery.