Struct WalBuffer 

pub struct WalBuffer { /* private fields */ }

In-memory WAL buffer for replication. Primary appends records here; replicas consume from it.

Each record payload is stored behind an Arc<[u8]> so fan-out to multiple replicas shares a single heap allocation per record (issue #832): a pull clones the Arc handle, never the bytes, so adding replicas does not multiply the primary’s send-buffer memory.

Implementations

impl WalBuffer

pub fn new(max_size: usize) -> WalBuffer

pub fn append(&self, lsn: u64, data: Vec<u8>)

Append a WAL record. Called by the storage engine after each write.

pub fn read_since( &self, since_lsn: u64, max_count: usize, ) -> Vec<(u64, Vec<u8>)>

Read records since the given LSN (exclusive), copying each payload into an owned Vec<u8>. Kept for callers (WAL archiving, retention bookkeeping) that need owned bytes; the per-replica fan-out path should prefer Self::read_since_shared to avoid copying.

pub fn read_since_shared( &self, since_lsn: u64, max_count: usize, ) -> Vec<(u64, Arc<[u8]>)>

Read records since the given LSN (exclusive) sharing the stored Arc<[u8]> payloads. Fan-out to N replicas clones only the reference-counted handles, so the buffer’s bytes are never duplicated per replica (issue #832).

pub fn current_lsn(&self) -> u64

Current LSN.

pub fn set_current_lsn(&self, lsn: u64)

pub fn prune_through(&self, upto_lsn: u64)

pub fn oldest_lsn(&self) -> Option<u64>

Oldest available LSN (for gap detection).