Struct WriteAheadLog 

pub struct WriteAheadLog { /* private fields */ }

Implementations

impl WriteAheadLog

pub fn new(store: Arc<dyn ObjectStore>, prefix: Path) -> Self

pub fn with_local_root(self, local_root: Option<PathBuf>) -> Self

Set the local filesystem root backing the object store, enabling fsync-on-flush. See the field docs on local_root.

pub async fn initialize(&self) -> Result<u64>

Initialize WAL state from existing segments (called on startup)

pub fn append(&self, mutation: Mutation) -> Result<()>

pub async fn flush(&self) -> Result<u64>

Flush buffered mutations to a WAL segment. Returns the LSN of the flushed segment.

pub fn flushed_lsn(&self) -> Result<u64, LockPoisonedError>

Get the highest LSN that has been flushed.

Errors

Returns error if the WAL state lock is poisoned (see issue #18/#150).

pub async fn replay_since(&self, high_water_mark: u64) -> Result<Vec<Mutation>>

Replay WAL segments with LSN > high_water_mark. Returns mutations from segments that haven’t been applied yet. Optimized to skip downloading segments with LSN <= high_water_mark (parsed from filename).

Corruption policy: a corrupt (bad checksum / unparseable / empty) segment at the tail of the log is the classic torn write from a crash — it is logged prominently and treated as end-of-WAL, since the commit it belonged to was never acknowledged. A corrupt segment with valid segments after it is real data loss and fails recovery with an error naming the file.

pub async fn replay(&self) -> Result<Vec<Mutation>>

Replay all WAL segments.

pub async fn truncate_before(&self, high_water_mark: u64) -> Result<()>

Deletes WAL segments with LSN <= high_water_mark by parsing filenames. Only downloads segments if filename parsing fails (fallback).

pub async fn has_segments(&self) -> Result<bool>

Check if any WAL segments exist (for detecting database with lost manifest).

pub async fn truncate(&self) -> Result<()>