miniRedis

miniRedis is a simplified, in-memory, asynchronous Redis-like server built with Rust and Tokio. It's a learning project that demonstrates how to build a high-performance TCP server that can handle multiple clients concurrently, parse the RESP (REdis Serialization Protocol), and execute a subset of Redis commands.

Overview

The server listens for incoming TCP connections on 127.0.0.1:6379. For each connection, it spawns a new asynchronous task to handle client communication. The server uses a shared, thread-safe, in-memory HashMap to store data.

The server's core logic is as follows:

1. Read data from the client.
2. Parse the data into a RESP message.
3. Parse the RESP message into a command.
4. Execute the command.
5. Write the response back to the client.

Features

The following commands are supported:

• PING: Returns PONG. Used to test if the connection is still alive.
• GET <key>: Returns the value of <key>. If the key does not exist, nil is returned.
• SET <key> <value>: Sets <key> to hold the string <value>.
• DEL <key> [key ...] : Removes the specified keys. A key is ignored if it does not exist.
• EXISTS <key> [key ...] : Returns the number of <key>s that exist.

RESP Implementation

The server implements a parser for the following RESP data types:

• Simple Strings (+)
• Simple Errors (-)
• Integers (:)
• Bulk Strings ($)
• Arrays (*)

Getting Started

Prerequisites

• Rust and Cargo
• A Redis client, like redis-cli

Running the server

1. Clone the repository:

   git clone <repository-url>
   cd miniRedis

2. Build and run the server:

   cargo run

The server will start and listen on 127.0.0.1:6379.

Usage

You can interact with the server using redis-cli in a separate terminal:

# Set a key
$ redis-cli SET mykey "Hello, world!"
OK

# Get a key
$ redis-cli GET mykey
"Hello, world!"

# Check if a key exists
$ redis-cli EXISTS mykey
(integer) 1

# Delete a key
$ redis-cli DEL mykey
(integer) 1

# Check if the key still exists
$ redis-cli GET mykey
(nil)

Project Structure

├── src
│   ├── main.rs            # Entry point, sets up the TCP listener and shared state
│   ├── handle_client.rs   # Main loop for handling a client connection
│   ├── model
│   │   └── types.rs       # Core data structures (DB, Command, RESP)
│   ├── parser
│   │   ├── mod.rs         # Exports the parser modules
│   │   ├── parse_resp     # Low-level RESP parsing functions
│   │   └── parse_command  # High-level command parsing from RESP Arrays
│   ├── controllers
│   │   ├── mod.rs         # Exports the command controller modules
│   │   ├── get.rs         # GET command implementation
│   │   ├── set.rs         # SET command implementation
│   │   ├── del.rs         # DEL command implementation
│   │   └── exists.rs      # EXISTS command implementation
│   └── util               # Utility functions
├── Cargo.toml             # Project dependencies and metadata
└── README.md              # This file