`ministate`

Minimal state manager with durable WAL logging
Part of the mini-rs embeddable toolkit

ministate gives you just enough: crash-safe, in-memory state with replayable history.

🎯 Purpose

ministate provides a simple yet robust way to maintain mutable application state that survives process restarts, using an append-only Write-Ahead Log (WAL) built on ministore.

Key features:

✅ In-memory state — fast reads via RwLock, full Clone on demand.
✅ Durable mutations — every change is fsynced before being applied.
✅ Crash recovery — full state restored by replaying WAL on startup.
✅ Logical sequencing — each mutation gets a monotonically increasing sequence number.
✅ Optional snapshots — enable snapshot feature for faster recovery (via minisnap).

Perfect for:

Component/deployment registries (e.g., in Arcella)
Queue metadata (e.g., in walmq)
Local coordination primitives (leader election, locks)
Embedded/IoT apps requiring crash-safe state

📦 Quick Start

Basic (WAL-only)

[dependencies]

ministate = "0.1"

serde = { version = "1.0", features = ["derive"] }

use ministate::{Mutator, StateManager};
use serde::{Deserialize, Serialize};

#[derive(Default, Clone, Serialize, Deserialize)]
struct Counter { value: u32 }

#[derive(Serialize, Deserialize)]
struct Inc { by: u32 }

impl Mutator<Counter> for Inc {
    fn apply(&self, state: &mut Counter) {
        state.value += self.by;
    }
}

let mgr = StateManager::open("./state", "counter.wal.jsonl").await?;
mgr.apply(Inc { by: 10 }).await?;
assert_eq!(mgr.snapshot().await.value, 10);

With Snapshots (opt-in)

[dependencies]

ministate = { version = "0.1", features = ["snapshot"] }

minisnap = "0.1"

mgr.create_snapshot().await?; // saves state + sequence number

✅ Guarantees

Guarantee	Description
Durability	If `apply().await` returns `Ok`, the mutation is on disk.
Atomicity	In-memory state is updated only after WAL write succeeds.
Ordering	Mutations applied in exact WAL order.
Recoverability	Full state restored from WAL (or WAL + snapshot).

🧩 Part of `mini-rs`

ministore — durable WAL engine
minisnap — optional snapshot & log compaction support
ministate — state manager (this crate)
miniqueue — durable message queue (in development)

Used in:

Arcella — component and deployment state
walmq — message queue metadata

📄 License

Dual-licensed under:

Apache License 2.0
MIT License

Choose the one that best fits your project.

ministate — because state should be simple, durable, and recoverable.
Part of the mini-rs family: simple, embeddable, reliable.

ministate 0.1.1

ministate