Redis in Rust

This started as a toy project for "Build Your Own Redis" Challenge it is now an attempt to do a complete re-write of Redis in Rust.

Commands

The following Redis commands have been implemented:

• SET [EX|PX]
• GET
• PING
• COMMAND DOCS (always returns +OK)
• ECHO
• DEL
• MGET
• STRLEN
• APPEND
• CONFIG GET
• KEYS
• INFO

Parameters

The following CLI parameters are currently supported:

• dir
• dbfilename
• replicaof

Design Overview

Supported commands

All the supported commands are defined as enums in protocol.rs.

Main loop

The main.rs tokio loop handles inbound connections:

loop {
    // Asynchronously wait for an inbound TcpStream.
    let (stream, _) = listener.accept().await?;

    // Must clone the handler because tokio::spawn move will grab everything.
    let set_command_handler_clone = set_command_actor_handle.clone();

    // Spawn our handler to be run asynchronously.
    // A new task is spawned for each inbound socket.  
    // The socket is moved to the new task and processed there.
    tokio::spawn(async move {
        process(stream, set_command_handler_clone)
            .await
            .expect("Failed to spawn process thread");
    });
}

Expiry loop

As part of the main initialization, we kick off a separate thread with an expiry channel. It listens for incoming requests to expire keys and acts accordingly.

NOTE: At the moment, this is a per redis expiry since this implementation supports a single database only.

Per-process loop

To ensure the server can handle multiple connections at the same time, every connection spawns a new thread and gets moved there immediately:

async fn process(stream: TcpStream, set_command_actor_handle: SetCommandActorHandle) -> Result<()> {}

Actor model

To avoid sharing state and dealing with mutexes, this code uses an actor model.