kv-concurrent 🚀

A small, educational concurrent key-value TCP server in Rust.

This project implements a simple in-memory key-value store that accepts plain-text commands over TCP. It's designed to demonstrate basic concurrency (thread-per-connection) using an Arc<Mutex<HashMap<_, _>>> and a minimal custom protocol for GET/SET/DEL operations.

Features ✅

• Simple, human-readable line-based protocol
• Concurrent clients handled with threads
• In-memory storage using HashMap protected by Mutex
• Minimal dependency surface (std only)

Protocol & Commands 🔧

All commands are single-line and terminated by a newline (\n). Arguments are separated by whitespace.

• GET <key> — returns the value or not found if missing
• SET <key> <value> — sets a key to a value and responds with OK
• DEL <key> — deletes a key and responds with the deleted value or not found

Note: Commands are case-sensitive (expect GET, SET, DEL).

Build & Run ⚡

Requirements: Rust (stable) toolchain.

Build and run locally:

# from the project root
cargo run

By default the server listens on 127.0.0.1:7978 and prints a message on startup:

concurrent server listening on port localhost:7978

Example Usage (with netcat) 🧪

Open a new terminal and run:

# set a key
printf "SET mykey hello\n" | nc 127.0.0.1 7978
# => OK

# get the key
printf "GET mykey\n" | nc 127.0.0.1 7978
# => hello

# delete the key
printf "DEL mykey\n" | nc 127.0.0.1 7978
# => deleted hello

You can also connect with telnet or any TCP client and issue newline-terminated commands interactively.

Limitations & Notes ⚠️

• This is an educational example, not intended for production use.
• The server uses a global Mutex, so concurrent access is serialized.
• No persistence — data is lost when the process exits.
• Error messages and command validation are intentionally minimal.

Contributing 🤝

Contributions and improvements are welcome. Open an issue or submit a pull request with changes or ideas.

License 📄

MIT — see LICENSE (or add one) for details.

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Thanks for checking out kv-concurrent! If you'd like, I can also:

• add example client scripts, or
• add a small test harness that exercises commands concurrently.