pub fn plan_rewind(log_path: &Path, to_turn: usize) -> Result<RewindPlan>Expand description
Compute a RewindPlan for rewinding to_turn.
to_turn is the turn index whose start state we want to
restore. So to_turn = 0 undoes everything; to_turn = 3
preserves turns 0..=2 and undoes 3 and later.
Goal 284: with on-demand checkpoints, the target checkpoint is
the id field of the most recent log entry with turn < to_turn,
or the pre field of the entry for to_turn (old auto-snapshot
sessions). If neither is available, returns an error.
Returns an error if the log doesn’t reach to_turn or if no
suitable checkpoint was recorded.