The acts_as_redis_counter plugin implements high performance counters using write-back strategy with Redis key-value database.

Installation

Install Redis server (http://code.google.com/p/redis/) and redis-rb gem from http://github.com/ezmobius/redis-rb

Install acts_as_redis_counter plugin:

  script/plugin install git://github.com/vitalie/acts_as_redis_counter.git

Howto use acts_as_redis_counter

Create migrations for your counters:

  class PostsAddViewsCountColumn < ActiveRecord::Migration
    def self.up
      add_column :posts, :views_count, :integer, :default => 0
    end

    def self.down
      remove_column :posts, :views_count
    end
  end

Define your Redis global connection in config/environment.rb:

  Rails::Initializer.run do |config|
    config.gem "redis"
    ...
    config.after_initialize do
      REDIS = Redis.new :host => '127.0.0.1'
    end
  end

In your models use acts_as_redis_counter to define your Redis counters.

  # optional parametters :ttl and :hits
  # writes to database will be delayed until one of the
  # conditions are meet *ttl* seconds or new *hits* number
  # Defaults:
  #  - ttl: 5.minutes
  #  - hits: 100

  class Post < ActiveRecord::Base
    acts_as_redis_counter :views_count, :ttl => 5.minutes, :hits => 100
    ...
  end

You can specify multiple counters on the same model:

  class Post < ActiveRecord::Base
    acts_as_redis_counter :views_count, :edits_count
    ...
  end

In your controllers increment and read your counters using plugin defined methods redis_counter_#{attribute} and redis_counter_#{attribute}_inc:

  # increment counter
  @post.redis_counter_views_count_inc

  # read counter
  @post.redis_counter_views_count