cache.rake

namespace :cache do
  namespace :fragment do

    desc 'Manually remove all fragment caches'
    task :delete => :environment do
      ActionController::Base.cache_store.clear
    end
  end
end

initializer.rb

    def initialize_cache
      unless defined?(RAILS_CACHE)
        silence_warnings { Object.const_set "RAILS_CACHE", ActiveSupport::Cache.lookup_store(configuration.cache_store) }

        if RAILS_CACHE.respond_to?(:middleware)
          # Insert middleware to setup and teardown local cache for each request
          configuration.middleware.insert_after(:"ActionController::Failsafe", RAILS_CACHE.middleware)
        end
      end
    end

    def initialize_framework_caches
      if configuration.frameworks.include?(:action_controller)
        ActionController::Base.cache_store ||= RAILS_CACHE
      end
    end