Method rollback_memtable_inserts

nodedb-columnar/src/mutation/engine.rs:216–238

Roll back in-memory inserts to `row_count_before`. Undoes the effect of one or more inserts that appended rows starting at `row_count_before`. For each inserted row: - The corresponding PK entry is removed from the PK index. - If the insert displaced a prior row (upsert tombstone), that prior row's PK index entry is restored and its tombstone bit cleared. The memtable is then truncated to `row_c

(
        &mut self,
        row_count_before: usize,
        inserted_pks: &[Vec<u8>],
        displaced: &[(Vec<u8>, crate::pk_index::RowLocation)],
    )

    /// The memtable is then truncated to `row_count_before`. Used exclusively
    /// by the transaction undo log; never called on the normal write path.
    pub fn rollback_memtable_inserts(
        &mut self,
        row_count_before: usize,
        inserted_pks: &[Vec<u8>],
        displaced: &[(Vec<u8>, crate::pk_index::RowLocation)],
    ) {
        // 1. Remove newly inserted PK entries.
        for pk in inserted_pks {
            self.pk_index.remove(pk);
        }
        // 2. Restore displaced prior-row PK entries and clear tombstones.
        for (pk, prior_location) in displaced {
            self.pk_index.upsert(pk.clone(), *prior_location);
            // Clear the tombstone bit that the insert set on the prior row.
            if let Some(bm) = self.delete_bitmaps.get_mut(&prior_location.segment_id) {
                bm.unmark_deleted(prior_location.row_index);
            }
        }
        // 3. Truncate memtable and surrogate list.
        self.memtable.truncate_to(row_count_before);
        self.memtable_surrogates.truncate(row_count_before);
        self.memtable_row_counter = row_count_before as u32;
    }

    /// The segment ID that will be assigned to the next flushed segment.
    ///