Method Cacheable

Cache method calls and speed up your Ruby on Rails application with MethodCacheable. It's kindof like cache_method but it's more explicit about what's being cached and how.

Simplicity Rules

This is a very very small library wrapped around Rails.cache api. It's goal is to be easy to use, and flexible (can be used without Rails). Currently method_cacheable weights in at about 200 lines with documentation (not counting tests and readme)

In your Model include MethodCacheable

app/models/user.rb

  class User < ActiveRecord::Base
    include MethodCacheable

    has_many :pictures

    def expensive_method(val)
      sleep 120
      return val
    end
  end

Then use the #cache method to fetch results from cache when available

  user = User.last

  # Call User#expensive_method normally
  Benchmark.measure { user.expensive_method(22) }.real
  # => 120.00037693977356

  # Fetch User#expensive_method from cache
  Benchmark.measure { user.cache.expensive_method(22) }.real
  # => 0.000840902328491211

Install

in your Gemfile

gem 'method_cacheable'

You will also want to have a library for caching objects. Such as dalli for using memcache

gem 'dalli'

Then run

bundle install

Set up Memcache

In your app/config/application.rb set your Rails cache store to use dalli

  config.cache_store = :dalli_store

In an initializer tell MethodCacheable to use the Rails.cache backend. You can use any object here that responds to #write, #read, and #fetch.

initializers/method_cacheable.rb

  MethodCacheable.config do |config|
    config.store = Rails.cache
  end

then in your models

include MethodCacheable

Now you're good to go, just use the cache method in that class and you can write, read and fetch any method from cache.

Usage

By default the cache method will will :fetch from the cache store. This means that if the key exists it will be pulled, if not the method will be called, returned, and the key will be set.

  user.cache(:read).expensive_method("w00t") # => nil
  user.cache.expensive_method("w00t")        # => "w00t" # sets the cache via :fetch
  user.cache.expensive_method("w00t")        # => "w00t" # pulls from the cache

You can also call :fetch explicitly if you prefer

  user.cache(:fetch).expensive_method("w00t")  # => "w00t" # pulls from the cache

Explicitly write & read methods.

  user.cache(:read).pictures  # => nil
  user.cache(:write).pictures # => [<# Picture ...>, <# Picture ...>] # refreshes the cache
  user.cache(:read).pictures  # => [<# Picture ...>, <# Picture ...>]

Different method arguments to the method generate different cache objects. I.E. different input => different output, same input => same output

  user.cache.expensive_method(:schneems => :is_awesome).inspect
  # => {:schneems => :is_awesome}
  user.cache.expensive_method("j/k lol").inspect
  # => "j/k lol"

Delete An Entry

You can delete any cached method using cache.delete and passing in the name of the method and any arguements, for example:

user.cache.expensive_method("w00t")           # => "w00t"

user.cache.delete(:expensive_method, "w00t")  # => nil

Configuration

Any configuration options passed to the cache method will be passed to the cache store (default is [Rails.cache](http://api.rubyonrails.org/classes/ActionController/Caching.html#method-i-cache Rails.cache))

  user.cache(:write, :expires_in => 5.seconds).pictures # => [<# Picture ...>, #... ]
  user.cache(:read).pictures                            # => [<# Picture ...>, #... ]
  sleep 10                                              # => 2
  user.cache(:read).pictures                            # => nil

Generate Keys

You don't need to generate keys, we do that for you using a library called keytar. If you want to see a key you can call key and pass in the name of the method and any arguments into it.

  User.find(9).cache.key(:foo) # => "users:foo:9"

Contribution

Fork away. If you want to chat about a feature idea, or a question you can find me on the twitters @schneems. Put any major changes into feature branches. Make sure all tests stay green, and make sure your changes are covered.

schneems/method_cacheable