query_cache.rb

require 'active_support/core_ext/object/blank'

module ActiveRecord
  class QueryCache
    module ClassMethods
      # Enable the query cache within the block if Active Record is configured.
      def cache(&block)
        if ActiveRecord::Base.configurations.blank?
          yield
        else
          connection.cache(&block)
        end
      end

      # Disable the query cache within the block if Active Record is configured.
      def uncached(&block)
        if ActiveRecord::Base.configurations.blank?
          yield
        else
          connection.uncached(&block)
        end
      end
    end

    def initialize(app)
      @app = app
    end

    def call(env)
      ActiveRecord::Base.cache do
        @app.call(env)
      end
    end
  end
end