Merb Cache

The merb-cache gem provides many options for caching your data including page and action caching, and different caching strategies including flat file and memcache.

• Merbunity has a good tutorial which explains this in more detail.
• There is detailed explanation of each methods (it uses the version of merb-cache from http://github.com/benschwarz/merb-cache/ a more up-to-date version with quite a few bug fixes and small changes of api)
• A description of the different cache stores is available here
• There is also an example application that uses caching hosted at GitHub.

First you must setup the Cache stores and strategies. Put the following code into your $MERB_ROOT/config/environments/production.rb. It will setup a page store and an action store. Both of which will be cached to the disk.

Merb::BootLoader.after_app_loads do
  Merb::Cache.setup do
    register(:page_store, Merb::Cache::PageStore[Merb::Cache::FileStore], :dir => Merb.root / "public")
    register(:action_store, Merb::Cache::ActionStore[Merb::Cache::FileStore], :dir => Merb.root / "tmp")
    register(:default, Merb::Cache::AdhocStore[:page_store, :action_store])
  end
end

You will want to add the following to your development.rb and test.rb, otherwise you will get errors on your cached actions.

Merb::BootLoader.after_app_loads do
  Merb::Cache.setup do
    register(:default, Merb::Cache::AdhocStore.new)
  end
end

Now you must specify which actions you want to cache. To do this, add the following line to your controller.

cache :index, :show

It will now cache your index and show pages to the public directory where they can be served from nginx, apache or your webserver of choice.

The pages are cached based on route, so if your url is http://server/cars/1, it will be cached to $MERB_ROOT/public/cars/1.html. If you nest routes, so your url is http://server/makes/1/car_models/2, then it will be cached to $MERB_ROOT/public/cars/1/car_models/2.html. Finally, if you use friendly urls, so your url looks like http://server/makes/ford/car_models/focus, then it will be cached to $MERB_ROOT/public/makes/ford/car_models/focus.html