redis_clone

A small Redis-like in-memory key-value server written in Rust.

This project is a learning-focused Redis clone. It speaks the Redis Serialization Protocol (RESP), accepts TCP clients with Tokio, and supports a growing set of Redis-style commands backed by an in-memory store.

What Works Now

• Starts a TCP server on 127.0.0.1:9000.
• Accepts multiple client connections with Tokio.
• Parses RESP arrays and bulk strings.
• Keeps a per-client read buffer for partial reads and pipelined commands.
• Encodes RESP responses.
• Supports PING, ECHO, SET, GET, DEL, EXISTS, INCR, DECR, EXPIRE, and TTL.
• Supports multi-key DEL and EXISTS.
• Stores string keys and values in memory with optional expiration times.
• Shares one store across client connections.
• Has integration tests for the store, RESP parser/encoder, and command layer.

Run

cargo run

The server should print:

redis_clone listening on 127.0.0.1:9000

Test With redis-cli

redis-cli -p 9000 ping
redis-cli -p 9000 echo hello
redis-cli -p 9000 set name shady
redis-cli -p 9000 get name
redis-cli -p 9000 incr count
redis-cli -p 9000 decr count
redis-cli -p 9000 exists name count missing
redis-cli -p 9000 expire name 3
redis-cli -p 9000 ttl name
redis-cli -p 9000 del name count missing

Expected output:

PONG
"hello"
OK
"shady"
(integer) 1
(integer) 0
(integer) 2
(integer) 1
(integer) 2 or 3
(integer) 2

Test Without redis-cli

Use nc to send a raw RESP command:

printf '*1\r\n$4\r\nPING\r\n' | nc 127.0.0.1 9000

Expected output:

+PONG

Current Architecture

src/
  main.rs    # Starts the async Tokio runtime and launches the server.
  server.rs  # Accepts TCP clients, parses RESP input, and writes responses.
  resp.rs    # Defines RESP values and parses/encodes Redis-compatible bytes.
  command.rs # Converts RESP arrays into commands and executes them.
  store.rs   # Holds the shared in-memory key-value store.

Learning Notes

• Redis Protocol Notes
• Architecture
• Supported Commands
• Development Guide
• Roadmap

Next Steps

1. Add append-only persistence and startup replay.
2. Add SET key value EX seconds syntax.
3. Extract shared numeric mutation logic for INCR and DECR.
4. Add more command tests for DEL, EXISTS, DECR, EXPIRE, and TTL.
5. Add richer data types like lists, sets, and hashes.