Tokio Chat Server Implementations

This repository contains two async chat server implementations in Rust using Tokio:

Implementation	Source
Single-threaded	server.rs
Multi-threaded	server.rs

Originally developed when I self-studied the Programming in Rust course at FEI VŠB-TUO. No solutions were available to me, I completely wrote the server.rs in both cases. I also added a simple terminal client.

Approaches

Single-threaded Version

Uses non-Send futures and internal channels for message routing. The internal channels are stored like this:

type ClientChannel = mpsc::Sender<ServerToClientMsg>;
type ClientMap = Rc<RefCell<HashMap<String, ClientChannel>>>;

Each client handler owns both reader and writer halves of the TCP stream. Messages are routed through channels before being written to the socket, ensuring sequential message processing on a single thread.

Multi-threaded Version

Uses Tokio's thread pool with locks and avoid internal channels. Per client there is one writer over the TCP stream stored in a map:

type SharedWriter = Mutex<MessageWriter<ServerToClientMsg, OwnedWriteHalf>>;
type ClientMap = Arc<RwLock<HashMap<String, SharedWriter>>>;

The writer half of the TCP stream is shared via the ClientMap, while each client handler future owns its reader.

How to use

Starting the server

From the project directory, run:

# Start the server (it will print the port number)
cargo run --bin server
# Example output: Server listening on port 46521

Connecting with a client

In another terminal, connect using:

cargo run --bin client -- --username <your_name> --port <server_port>

# Example:
cargo run --bin client -- --username alice --port 46521

Available chat commands

Once connected, you can use these commands:

• /h - Show help menu
• /l - List connected users
• /d <user> <message> - Send private message
• /b <message> - Broadcast message to all users
• /q - Quit the chat

Features

• Client name choice via Join messages
• Direct messaging between clients
• Broadcast messages to all connected clients
• User listing