Crate cronoq_store_sqlite 

cronoq-store-sqlite

A SQLite Store for cronoq: durable state in one local file, no database server.

• Write-ahead state: every engine state transition is committed in batches, one transaction per batch, before submitters are acknowledged. The file uses SQLite’s WAL journal and, by default, syncs it on every commit.
• Leader and standbys: several processes on the same host may open the same file. One leads through a lease row in cronoq_leader that it renews; the others wait and take over once the lease runs out. Taking over bumps a fencing epoch.
• Fencing: each commit re-reads the epoch and lease holder inside its write transaction (SQLite serializes writers) and fails with StoreError::Fenced if another process took over, so a paused old leader can never write after a standby replaced it.
• Recovery: a new leader loads live tasks, recently finished ones (for key deduplication), every finished task a live task still depends on, and recurring schedules. Rows that cannot be decoded are quarantined (marked failed).
• Files: the database is created readable and writable by its owner only (on Unix). Keep it on a local filesystem: SQLite’s WAL mode does not work over network filesystems.

Times are stored as wall-clock Unix nanoseconds; strings are stored with NUL replaced by U+FFFD, as in the PostgreSQL store. Lease expiry uses the wall clock, which processes on one host share.

use bytes::Bytes;
use cronoq::{Pool, Scheduler};
use cronoq_store_sqlite::SqliteStore;

let store = SqliteStore::open("/var/lib/cronoq/state.db").await?;
let sched = Scheduler::<Bytes, Bytes>::builder()
    .pool(Pool::new("default").executor_fn(|_ctx, p: std::sync::Arc<Bytes>| async move {
        Ok::<_, cronoq::TaskError>((*p).clone())
    }))
    .store(store.clone())
    .build() // blocks until this process is the leader
    .await?;
tokio::select! {
    _ = store.leadership_lost() => { /* step down: stop serving, exit or rejoin */ }
    _ = tokio::signal::ctrl_c() => {}
}

Structs

SqliteStore

SQLite-backed Store. Cheap to clone.

SqliteStoreConfig

Store configuration.

Type Aliases

TaskRecord

Persisted view of a task, for lookups by id or key.