Struct WalWriter 

pub struct WalWriter { /* private fields */ }

Append-only WAL writer.

Implementations

impl WalWriter

pub fn open(path: &Path, config: WalWriterConfig) -> Result<Self>

Open or create a WAL file at the given path.

pub fn set_encryption_key(&mut self, key: WalEncryptionKey) -> Result<()>

Set the encryption key. When set, all subsequent records will have their payloads encrypted with AES-256-GCM.

Writes the 16-byte WAL segment preamble at the current file offset. Must be called before the first append. Calling it after records have already been written to this file returns an error.

pub fn set_encryption_ring(&mut self, ring: KeyRing) -> Result<()>

Set the key ring directly (for key rotation with dual-key reads).

Writes the 16-byte WAL segment preamble at the current file offset. Must be called before the first append. Calling it after records have already been written to this file returns an error.

pub fn encryption_ring(&self) -> Option<&KeyRing>

Access the key ring (for decryption during replay).

pub fn segment_preamble(&self) -> Option<&SegmentPreamble>

The preamble for this segment, if encryption was enabled.

pub fn open_with_start_lsn( path: &Path, config: WalWriterConfig, start_lsn: u64, ) -> Result<Self>

Open a new WAL segment file with a specific starting LSN.

Used by SegmentedWal when rolling to a new segment. The file must not already exist (or be empty). The writer will assign LSNs starting from start_lsn.

pub fn open_without_direct_io(path: &Path) -> Result<Self>

Open a WAL writer with O_DIRECT disabled (for testing on tmpfs, etc.).

pub fn append( &mut self, record_type: u32, tenant_id: u64, vshard_id: u32, database_id: u64, payload: &[u8], ) -> Result<u64>

Append a record to the WAL. Returns the assigned LSN.

The record is written to the in-memory buffer. Call sync() to flush to disk and make the write durable.

database_id is stored in header bytes 34-41. Pass 0 for the default database (backward-compatible with pre-existing records).

pub fn sync(&mut self) -> Result<()>

Flush the write buffer to disk (group commit).

This issues a single write + fsync for all records accumulated since the last flush. The DWB is also fsynced (one fsync for all deferred DWB writes in this batch).

pub fn seal(&mut self) -> Result<()>

Seal the WAL — no more writes will be accepted.

Flushes any buffered data before sealing.

pub fn next_lsn(&self) -> u64

The next LSN that will be assigned.

pub fn file_offset(&self) -> u64

Current file size (bytes written to disk).