Struct MemStore 

pub struct MemStore { /* private fields */ }

An in-memory WalStore backed by a Vec<u8> behind a short lock.

Everything a FileStore does, without touching the filesystem, including the sparse-file behaviour of zero-filling a gap when a higher offset is written first. sync is a no-op — memory has no separate durable tier — so a MemStore is for tests, examples, and benchmarking the framing path in isolation, not for durability.

Examples

use wal_db::{MemStore, Wal};

let wal = Wal::with_store(MemStore::new())?;
let lsn = wal.append(b"in memory")?;
assert_eq!(lsn.get(), 0);

Implementations

impl MemStore

pub fn new() -> Self

Create an empty in-memory store.

pub fn with_capacity(capacity: usize) -> Self

Create an empty store that has pre-allocated room for capacity bytes, to avoid reallocations during a known-size workload.

pub fn from_bytes(bytes: Vec<u8>) -> Self

Create a store preloaded with bytes — for example a log image captured elsewhere, so Wal::with_store can recover it.

Trait Implementations

impl Clone for MemStore

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MemStore

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

Formats the value using the given formatter.

impl Default for MemStore

fn default() -> MemStore

Returns the “default value” for a type.

impl WalStore for MemStore

fn write_at(&self, offset: u64, bytes: &[u8]) -> Result<()>

Write bytes at byte offset, growing the store and zero-filling any gap if offset is beyond the current end.

fn read_at(&self, offset: u64, buf: &mut [u8]) -> Result<usize>

Read into buf starting at byte offset, returning the number of bytes read.

fn truncate(&self, len: u64) -> Result<()>

Discard every byte at or after len, shrinking the store to exactly len bytes.

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

Flush every preceding write_at to stable storage.

fn len(&self) -> Result<u64>

The current size of the store in bytes.

fn is_empty(&self) -> Result<bool>

Whether the store holds no bytes.

fn head(&self) -> Result<u64>

The lowest offset that still holds data.

fn truncate_before(&self, _offset: u64) -> Result<u64>

Discard storage entirely below offset, if the backend can, returning the new head.