Struct UndoBuffer 

pub struct UndoBuffer { /* private fields */ }

Accumulates undo records for a single write transaction.

Implementations

impl UndoBuffer

pub fn new() -> Self

pub fn record( &mut self, table_id: u64, row_id: u64, column: u32, old_data: Vec<u8>, )

Record the old value of a cell before it is overwritten.

pub fn len(&self) -> usize

Number of undo records accumulated.

pub fn is_empty(&self) -> bool

Whether the buffer is empty.

pub fn clear(&mut self)

Clear all records (called on successful commit).

pub fn drain(&mut self) -> Vec<UndoRecord>

Drain all records out of the buffer (consuming). Used when the caller needs to take ownership of the records for rollback application.

pub fn rollback<F>(&mut self, apply_fn: F) -> Result<(), StorageError>

where F: FnMut(&UndoRecord) -> Result<(), StorageError>,

Apply all undo records in reverse order.

The apply_fn callback receives each undo record and should write old_data back to the appropriate table/row/column. Records are applied in reverse order (LIFO) so that the last write is undone first — preserving intermediate states.

Trait Implementations

impl Debug for UndoBuffer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for UndoBuffer

fn default() -> UndoBuffer

Returns the “default value” for a type.