saarons/redlock-rb

Redlock Redis-based distributed locks implementation in Ruby

Redlock - A ruby distributed lock using redis.

Distributed locks are a very useful primitive in many environments where different processes require to operate with shared resources in a mutually exclusive way.

There are a number of libraries and blog posts describing how to implement a DLM (Distributed Lock Manager) with Redis, but every library uses a different approach, and many use a simple approach with lower guarantees compared to what can be achieved with slightly more complex designs.

This is an implementation of a proposed distributed lock algorithm with Redis. It started as a fork from antirez implementation.

Installation

Add this line to your application's Gemfile:

gem 'redlock'

And then execute:

$ bundle

Or install it yourself as:

$ gem install redlock

Documentation

RubyDoc

Usage example

  # Locking
  lock_manager = Redlock::Client.new([ "redis://127.0.0.1:7777", "redis://127.0.0.1:7778", "redis://127.0.0.1:7779" ])
  first_try_lock_info = lock_manager.lock("resource_key", 2000)
  second_try_lock_info = lock_manager.lock("resource_key", 2000)

  # it prints lock info {validity: 1987, resource: "resource_key", value: "generated_uuid4"}
  p first_try_lock_info
  # it prints false
  p second_try_lock_info

  # Unlocking
  lock_manager.unlock(first_try_lock_info)
  second_try_lock_info = lock_manager.lock("resource_key", 2000)

  # now it prints lock info
  p second_try_lock_info

There's also a block version that automatically unlocks the lock:

lock_manager.lock("resource_key", 2000) do |locked|
  if locked
    # critical code
  else
    # error handling
  end
end

Run tests

Make sure you have at least 1 redis instances up.

$ rspec

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request