final case class GlobalLogBacking(file: File, last: Option[File], newBackingFile: () => File)
Tracks the files that persist the global logging. file is the current backing file. last is
the previous backing file, if there is one. newBackingFile creates a new temporary location for
the next backing file.
If there is a previous backing file in last, that becomes the current backing file and the
previous backing is cleared. Otherwise, no changes are made.
If there is a previous backing file in last, that becomes the current backing file and the
previous backing is cleared. Otherwise, no changes are made.