LOCK.md

Lock

Named locks live in serenade-lock (#185, #190, #191).

Symfony Lock analogue for critical sections (cron, inventory, mail blast). Apps own lock key naming.

Types

Type	Role
LockStore	Persist ownership (save / delete / exists / put_off_expiration)
LockFactory / Lock	Create handles; acquire / release / refresh / is_acquired
LockKey	Resource name + opaque owner token
LockError	Invalid key, conflict, not held, generation, store failures

Stores

Store	Role
InMemoryLockStore	Process-local (default DI)
FilesystemLockStore	Disk files under {directory}/{prefix}/{hex}.lock
RedisLockStore	Redis via redis-rs + r2d2 (Cargo feature redis)

DI

FrameworkExtension adds [RegisterDefaultLockPass], which registers service id lock.store (DEFAULT_LOCK_STORE_SERVICE) tagged lock.store with an InMemoryLockStore when missing. Resolve LockStoreService and call factory().

Apps replace the default by registering filesystem or Redis stores under the same id before compile.

Example

use std::sync::Arc;
use std::time::Duration;
use serenade_lock::{InMemoryLockStore, LockFactory, LockStore};

let store = Arc::new(InMemoryLockStore::new());
let factory = LockFactory::new(store);
let lock = factory.create_lock("cron:mail-blast", Some(Duration::from_secs(30)), true)?;
if lock.acquire()? {
    // critical section
    lock.release()?;
}

Filesystem:

use serenade_lock::{FilesystemLockStore, FilesystemLockStoreConfig};

let store = FilesystemLockStore::open(
    FilesystemLockStoreConfig::new("var/lock").with_prefix("serenade"),
)?;

Redis (feature redis):

use serenade_lock::{RedisLockStore, RedisLockStoreConfig};

let store = RedisLockStore::connect(
    RedisLockStoreConfig::new("redis://127.0.0.1:6379/0").with_prefix("serenade:lock:"),
)?;

Related

• Parent epic: #185
• Cache Redis patterns: CACHE.md