Struct TxnWalEntry 

pub struct TxnWalEntry {
    pub record_type: WalRecordType,
    pub txn_id: TxnId,
    pub timestamp_us: u64,
    pub key: Option<Vec<u8>>,
    pub value: Option<Vec<u8>>,
    pub table: Option<String>,
    pub checksum: u32,
    pub lsn: Lsn,
    pub prev_lsn: Option<Lsn>,
    pub page_id: Option<PageId>,
    pub undo_info: Option<Vec<u8>>,
    pub undo_next_lsn: Option<Lsn>,
}

WAL entry with ARIES transaction support

Extends standard WAL entries with ARIES-specific fields:

• LSN: Log Sequence Number for ordering and idempotent recovery
• prev_lsn: Previous LSN for this transaction (undo chain)
• undo_info: Before-image for undo operations
• page_id: Page affected by this operation

Fields

record_type: WalRecordType

Type of this WAL record

txn_id: TxnId

Transaction ID

timestamp_us: u64

Timestamp in microseconds

key: Option<Vec<u8>>

Optional key for data records

value: Option<Vec<u8>>

Optional value for data records (after-image)

table: Option<String>

Optional table name

checksum: u32

CRC32 checksum

lsn: Lsn

ARIES: Log Sequence Number (assigned when appended to WAL)

prev_lsn: Option<Lsn>

ARIES: Previous LSN in this transaction’s chain (for undo)

page_id: Option<PageId>

ARIES: Page ID affected by this record

undo_info: Option<Vec<u8>>

ARIES: Before-image for undo (original value before update)

undo_next_lsn: Option<Lsn>

ARIES: For CLRs, the next LSN to undo (skips compensated operations)

Implementations

impl TxnWalEntry

pub const FORMAT_VERSION: u8 = 0x01

Wire format version for forward/backward compatibility.

• V0 (0x00): Legacy 6-field format (record_type, txn_id, timestamp_us, key, value, table, checksum). ARIES fields are NOT serialized; from_bytes() defaults them to zero/None.
• V1 (0x01): Full ARIES format. All fields serialized including lsn, prev_lsn, page_id, undo_info, undo_next_lsn. Checksum covers ALL fields.

pub fn new_begin(txn_id: TxnId, timestamp_us: u64) -> Self

pub fn new_commit(txn_id: TxnId, timestamp_us: u64) -> Self

pub fn new_abort(txn_id: TxnId, timestamp_us: u64) -> Self

pub fn new_data( txn_id: TxnId, timestamp_us: u64, table: String, key: Vec<u8>, value: Option<Vec<u8>>, ) -> Self

pub fn new_aries_data( txn_id: TxnId, timestamp_us: u64, table: String, key: Vec<u8>, value: Option<Vec<u8>>, page_id: PageId, prev_lsn: Option<Lsn>, undo_info: Option<Vec<u8>>, ) -> Self

Create a new ARIES-style data record with before-image for undo

pub fn new_clr( txn_id: TxnId, timestamp_us: u64, table: String, key: Vec<u8>, value: Option<Vec<u8>>, page_id: PageId, prev_lsn: Lsn, undo_next_lsn: Lsn, ) -> Self

Create a Compensation Log Record (CLR) for ARIES undo

CLRs are redo-only records that describe undo operations. They include undo_next_lsn which points to the next record to undo, skipping the compensated operation.

pub fn new_checkpoint_end( timestamp_us: u64, checkpoint_data: AriesCheckpointData, ) -> Result<Self, String>

Create a checkpoint end record with recovery data

pub fn get_checkpoint_data(&self) -> Option<AriesCheckpointData>

Extract checkpoint data from a CheckpointEnd record

pub fn compute_checksum(&mut self)

Calculate and set checksum

pub fn verify_checksum(&self) -> bool

Verify checksum

pub fn to_bytes(&self) -> Vec<u8>

Serialize to bytes (versioned wire format)

Format V1 layout:

[version:1] [serialize_for_checksum payload] [crc32:4]

pub fn from_bytes(data: &[u8]) -> Result<Self, String>

Deserialize from bytes with proper error propagation

Supports both wire format versions:

• V0 (legacy): No version byte; first byte is a valid WalRecordType discriminant. ARIES fields default to zero/None.
• V1: First byte is 0x01 (FORMAT_VERSION). All ARIES fields deserialized.

Returns an error if:

• Data is too short
• Record type is invalid
• Data is truncated mid-field
• UTF-8 encoding is invalid for table name
• Checksum validation fails

Trait Implementations

impl Clone for TxnWalEntry

fn clone(&self) -> TxnWalEntry

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TxnWalEntry

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for TxnWalEntry

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for TxnWalEntry

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.