Rust Mini-Redis

A lightweight, blazingly-fast in-memory key-value store inspired by Redis, built with Rust and Tokio. It provides an async TCP server that handles multiple data types and automatic key expiration — all with a single external dependency.

Why I Built This

Redis is one of those tools you use daily without thinking much about how it works under the hood. I built this project to understand the internals — how keys expire, how a TCP server handles concurrent connections, and how you model different data types in memory. Rust was the natural choice: it forces you to think carefully about ownership and concurrency, which are exactly the things that matter in a storage engine.

Features

• In-memory key-value storage with automatic TTL management
• Support for three value types: strings, lists (comma-separated), and hashes (key:value pairs)
• Nine core commands for full CRUD, introspection, and server health
• Asynchronous server architecture powered by Tokio
• Single dependency — just Tokio, nothing else

Getting Started

You only need Rust installed. Clone the repo and run:

cargo run

The server starts on 127.0.0.1:6379. Connect with NetCat:

# macOS
nc 127.0.0.1 6379

# Linux
nc -q 0 127.0.0.1 6379

Or pipe single commands directly:

echo "SET name Alice" | nc 127.0.0.1 6379
echo "GET name" | nc 127.0.0.1 6379

You can also use redis-cli:

redis-cli SET name ALICE 120

Commands

Command	Syntax	Description
SET	SET <key> <value> [ttl]	Store a value with optional TTL (default 60s)
GET	GET <key>	Retrieve a value; returns Nil if absent or expired
UPDATE	UPDATE <key> <value> [ttl]	Modify an existing key; supports type changes
DEL	DEL <key>	Remove a key
EXISTS	EXISTS <key>	Returns YES or NO
RENAME	RENAME <old_key> <new_key>	Rename a key
TYPE	TYPE <key>	Returns String, VecStr, or Hash
CLEARALL	CLEARALL	Wipe all stored data
PING	PING	Health check — responds with PONG

Data Types

Strings — plain values:

SET greeting "Hello, world"

Lists — comma-separated values:

SET colors red,green,blue

Hashes — key:value pairs, comma-separated:

SET user name:Alice,age:30,city:Lagos

The UPDATE command lets you change a key’s type entirely, so you can transition a string into a hash without deleting and recreating it.

Project Structure

src/
├── main.rs      # Entry point, bootstraps the Tokio runtime
├── runner.rs    # TCP server loop and command parsing
└── state.rs     # In-memory store with TTL expiration logic

Technologies Used

• Rust — Systems programming language for performance and memory safety
• Tokio — Async runtime for handling concurrent TCP connections

Source Code

View the full source on GitHub at github.com/Aliemeka/rs-miniredis.