Build your own Redis in Ruby

Sibling to the Python, Go, Node.js, and Rust workshops. Same architectural progression, idiomatic Ruby with socket, Thread, Mutex, Queue, and ConditionVariable.

The build

#	Step	Ruby idiom
01	TCP echo	TCPServer + Thread per connection
02	RESP parser	byteslice + tagged-array sum type
03	GET / SET	Hash + Mutex.synchronize + case/when
04	Expiry	sidecar Hash + Time.now.to_f deadlines
05	AOF persistence	File.open('ab') + log_to_aof: false
06	RDB snapshots	JSON.dump + File.rename atomic
07	Pub/Sub	per-subscriber Queue + write-pump Thread
08	Replication	master/replica via ARGV + SYNC
09	Graceful shutdown	Signal.trap + ConditionVariable + RDB on exit
10	Capstone benchmark	sequential RESP load + percentile report

Each step folder ships with server.rb, README.md, GUIDE.md, EXERCISES.md.

Getting started

Requires Ruby 3.0+.

git clone https://github.com/learnwithparam/build-your-own-redis-ruby.git
cd build-your-own-redis-ruby
make 01-tcp-echo

In another terminal:

nc localhost 6380
> hello
< hello

Run any step

make 01-tcp-echo
make 02-resp-parser
make 03-get-set
make 04-expiry
make 05-aof-persistence
make 06-rdb-snapshots
make 07-pubsub
make 08-replication             # master on 6380; replica with: ruby 08-replication/server.rb replica 6381 127.0.0.1 6380
make 09-graceful-shutdown
make 10-capstone                # benchmark vs real Redis on 6379
make test                       # ruby -c every server file + doc check

Why Ruby

• Threads + GIL: enough for an IO-bound server; honest about its CPU ceiling
• Mutex.synchronize: block-scoped lock acquisition, exception-safe by design
• Queue and ConditionVariable: lock-free coordination primitives shipped in stdlib
• Signal.trap: clean signal handling without sigaction(2) ceremony
• Fiber.schedule (Ruby 3+): bonus path to a single-threaded event loop in exercise 1.4

Sibling workshops

• Build your own Redis in Python
• Build your own Redis in Go
• Build your own Redis in Node.js
• Build your own Redis in Rust

Concept	Python	Go	Node	Rust	Ruby
Concurrency	Threads or selectors	Goroutines	Event loop	tokio tasks	Threads (+ Fiber 3+)
Shared state	dict + lock	sync.RWMutex	Map (no lock)	Arc<Mutex>	Hash + Mutex
Pub/Sub fan-out	Connection list	Buffered chan	Set	broadcast channel	Queue per subscriber
Sum type	duck typing	interface{}	discriminated objects	enum	tagged array

License

MIT.