FindCache

It is simply an ActiveRecord object caching gem using Rails.cache methods.

It makes “ActiveRecord ‘find_by_id, find_by_(attr)’ methods and ‘has_one, belongs_to’ relations” cacheable by id or any referenced columns using Rails.cache methods. It also supports fetching multiple records using ids with find_all_cache method(if cache store supports multiple reads [hint: memcached_store, dalli_store supports.]).

Installation

Add this line to your application’s Gemfile:

gem 'find_cache'

And then execute:

$ bundle

Or install it yourself as:

$ gem install find_cache

For has_one and belongs_to relations

### Sample Models:

class User < ActiveRecord::Base
  has_one :user_detail

  # to enable has_one caching
  find_cache_has_one :user_detail, UserDetail, :user_id 
end

class UserDetail < ActiveRecord::Base
  belongs_to :user

  # to enable belongs_to caching
  find_cache_belongs_to :user, User, :user_id 
end

For finding a record

user = User.find_cache(id) # fetches from cache
user.user_detail
# fetches from cache if the User model has
# 'find_cache_has_one :user_detail, UserDetail, :user_id'

user = User.find_by_id(id) # fetches from DB
user.user_detail # fetches from DB

For fetching multiple ids

users = User.find_all_cache([1,2,3,4,5])

For fetching a record by attribute

user_detail = UserDetail.find_by_user_id(1) # from db
user_detail = UserDetail.find_cache_by_ref(:user_id, 1) # from cache store

For counter_cache ‘cache invalidation’

### Create a ruby file under config/initializers and add the following codes:

module ActiveRecord
  module CounterCache
    def increment_counter(counter_name, id)
      expire_find_cache(name, id)
      update_counters(id, counter_name => 1)
    end

    def decrement_counter(counter_name, id)
      expire_find_cache(name, id)
      update_counters(id, counter_name => -1)
    end

    def expire_find_cache(name, id)
      key = FindCache::KeyGen.cache_key(name, id)
      Rails.cache.delete(key)
      $find_cache_store[FindCache::KeyGen.global_cache_key].delete(key)
    end
  end
end

Notes

If your worker thread does not kill itself after execution you should clean the find_cache_store manually. It can be done simple in ApplicationController of your rails app adding this method as after_filter

after_filter :clear_find_cache_store

def clear_find_cache_store
  FindCache::KeyGen.clear_find_cache_store
end

Tested with dalli (github.com/mperham/dalli).

Credits

FindCache is part of videofork.com project.

Contributing

1. Fork it

2. Create your feature branch (‘git checkout -b my-new-feature`)

3. Commit your changes (‘git commit -am ’Added some feature’‘)

4. Push to the branch (‘git push origin my-new-feature`)

5. Create new Pull Request