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

🧩 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.