ar-async-counter-cache

---

This gem allows you to update ActiveRecord counter cache columns asynchronously. You may want to do this in situations where you want really speedy inserts and have models that “belong_to” many different parents.

You use it like such:

class User < ActiveRecord::Base
  has_many :comments
  has_many :posts
end

class Post < ActiveRecord::Base
  belongs_to :user, :async_counter_cache => true
  has_many :comments
end

class Comment < ActiveRecord::Base
  belongs_to :user, :async_counter_cache => true
  belongs_to :post, :async_counter_cache => "count_of_comments"
end

Notice, you may specify the name of the counter cache column just as you can with the normal belongs_to :counter_cache option. You also may not use both the :async_counter_cache and :counter_cache options in the same belongs_to call.

All you should need to do is require this gem in your project that uses ActiveRecord and you should be good to go;

e.g. In your Gemfile:

  gem 'ar-async-counter-cache', '0.0.1'

and then in RAILS_ROOT/config/environment.rb somewhere:

  require 'ar-async-counter-cache'

This gem has built-in support for Resque (github.com/defunkt/resque). Al you need is resque in your loadpath:

e.g. In your Gemfile:

  gem 'resque', '1.9.4'

By default, the Resque job is placed on the :default queue:

@queue = :default

However, you can change this:

in RAILS_ROOT/config/environment.rb somewhere:

  ArAsyncCounterCache.resque_job_queue = :low_priority

If you don’t want to use Resque, you must define one instance method for your models using ar-async-counter-cache:

e.g.:

  Comment#async_increment_counters

That method should pass a message onto a queue for a background processor to handle later. That background processor should call:

Comment#update_async_counters(:increment)