Age past which a leftover checkpoint temp file is treated as abandoned. A
committed write renames its temp file into place within microseconds of
creating it. A temp file older than this was never renamed, which means the
process that created it exited before finishing the write.
Returns whether name would produce a checkpoint file that collides with
the reserved temporary-write namespace. Such a name cannot be used because a
directory scan would treat its checkpoint as an in-progress write and ignore
it.
Remove checkpoint temp files in directory left behind by a process that
crashed between writing and renaming a checkpoint. Only entries older than
max_age are removed, leaving a temp file currently being written by
another consumer process untouched. Best-effort: a missing directory or a
per-entry failure is skipped rather than reported.