Punchline

Punchline is a Redis backed Minimum Priority Queue with enforced uniqueness and atomicity fuelled by lua scripts.

Motivation

At Doceo, we needed a way to atomically keep track of dirty records that needed reprocessing, whilst also avoiding doing extra work if records are marked as dirty and haven't been processed yet.

Prerequisites

Redis 2.6+

Currently tested against Ruby 2.0.0, 2.1.0 and JRuby

Installation

Add this line to your application's Gemfile:

gem 'punchline', '~> 0.1.0'

Or live on the bleeding edge

gem 'punchline', github: 'catkins/punchline'

And then execute:

$ bundle install

Usage

require 'punchline'

# optionally override Punchline with your own Redis client, eg. Redis::Namespace
redis_url = ENV["REDIS_URL"] || "redis://localhost:6379"
client = Redis.new url: redis_url
namespaced_client = Redis::Namespace.new Rails.env, client

Punchline.configure do |config|
  config.redis = namespaced_client
end

# create a queue
queue = Punchline::MinQueue.new :awesome_key
queue.length # => 0

# add a key - priority defaults to current timestamp (Time.now.to_i)
queue.enqueue 'hello!' # => true

queue.length # => 1

# shortly after... higher priority score is rejected
queue.enqueue 'hello!' # => false

queue.length # => 1

# original key is retrieved
queue.dequeue # => { :priority => 1411405014, :value => "hello!" }

# queue is now empty
queue.length # => 0

# optionally set your own priority value
queue.enqueue 'hello!', priority: 155 # => true

# fetch all without dequeuing
queue.enqueue 'hello!'
queue.enqueue 'adding values!'
queue.all # [{:value=>"hello!", :priority=>155}, {:value=>"adding values!", :priority=>1411446073}]

# clear out queue
queue.clear!
queue.all # => []
queue.length # => 0

Contributing

Fork it ( http://github.com/catkins/punchline/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

punchline