ActionController::Caching
Caching is a cheap way of speeding up slow applications by keeping the result of calculations, renderings, and database calls around for subsequent requests. Action Controller affords you three approaches in varying levels of granularity: Page, Action, Fragment.
You can read more about each approach and the sweeping assistance by clicking the modules below.
Note: To turn off all caching and sweeping, set Base.perform_caching = false.
Files
- actionpack/lib/action_controller/caching.rb
Nested classes and modules
- ActionController::Caching::Actions
- ActionController::Caching::Fragments
- ActionController::Caching::Pages
- ActionController::Caching::Sweeper
- ActionController::Caching::Sweeping
3Notes
Using sweepers in script/runner
If you need to use some of your sweepers in a script/runner script or some rake task you can use this snipped:
require 'action_controller/test_process'
sweepers = [ProductSweeper, UserSweeper]
ActiveRecord::Base.observers = sweepers
ActiveRecord::Base.instantiate_observers
controller = ActionController::Base.new
controller.request = ActionController::TestRequest.new
controller.instance_eval do
@url = ActionController::UrlRewriter.new(request, {})
end
sweepers.each do |sweeper|
sweeper.instance.controller = controller
end
Your script will fire the ActiveRecord callbacks defined in that sweepers and you can use +expire_cache+, +expire_fragment+ and also the routing helpers you have defined (+hash_for_user_path+, +hash_for_product_path+, etc.).
Rails 2.1 caching internals
Rails 2.1 caching features are pretty much undocumented. Rob Anderton has documented some internal stuff here:
http://www.thewebfellas.com/blog/2008/6/9/rails-2-1-now-with-better-integrated-caching
Video tutorial
If you want to get up to speed with Rails' caching and haven't seen it already, definitely check out this video series on Scaling Rails: