godis ⚡

godis is a lightweight Redis clone implemented from scratch in Go, designed to explore TCP servers, concurrency safety, correct Redis semantics and clean internal architecture.

It implements a meaningful subset of Redis commands while preserving correct semantics such as FIFO ordering, blocking behaviour, and safe concurrent access.

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🚀 Features

Core

• Built as a TCP server
• Redis-compatible RESP protocol
• Concurrent client handling
• Safe access using mutexes, condition variables, and sync.Map
• Redis-style command dispatch

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📦 Supported Data Types & Commands

🔑 Strings

• SET
  • Supports expiration:
    • EX (seconds)
    • PX (milliseconds)
• GET

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📃 Lists

• LPUSH
• RPUSH
• LPOP
• BLPOP (blocking with timeout, FIFO-safe)
• LLEN
• LRANGE

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🌊 Streams

• XADD
• XRANGE
• XREAD

Streams are implemented with:

• Blocking reads where applicable
• Auto-generated IDs (*)
• Strict ID ordering enforcement

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⚙️ Server / Utility Commands

• TYPE
• CONFIG GET / SET
• PING, ECHO, QUIT

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🧠 Concurrency Model

godis is built to handle multiple concurrent clients safely and efficiently.

Techniques Used:

• sync.Map for the global keyspace (read-heavy workload)
• Fine-grained mutexes per data structure:
  • Lists & Streams have their own locks
• Blocking commands (BLPOP, XREAD) use:
  • Waiter queues
  • Condition variables
• FIFO fairness guaranteed for blocked clients

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📜 Demo

This project is fully compatible with the official Redis CLI, allowing it to be demonstrated exactly like a real Redis server. First, ensure that redis-cli is installed on your system. For Windows, unfortunately, there is no direct way to use it other than WSL or a VM.

Once that's taken care of, start the server with

go run ./cmd/server/

Then, in another terminal window, connect using Redis CLI and use the server:

redis-cli -p 6379

Or run the demo script using

./demo.sh