query_cache_.rb

gistfile1.rb

require 'rack/body_proxy'
require 'active_record/query_cache'

module ActiveRecord
  module Turntable
    module Rack
      class QueryCache < ActiveRecord::QueryCache
        def call(env)
          enabled       = ActiveRecord::Base.connection.query_cache_enabled
          connection_id = ActiveRecord::Base.connection_id
          klasses = ActiveRecord::Base.turntable_connections.values
          klasses.each do |k|
            k.connection.enable_query_cache!
          end

          response = @app.call(env)
          response[2] = ::Rack::BodyProxy.new(response[2]) do
            restore_query_cache_settings(connection_id, enabled)
          end

          response
        rescue Exception => e
          restore_query_cache_settings(connection_id, enabled)
          raise e
        end

        private

        def restore_query_cache_settings(connection_id, enabled)
          klasses = ActiveRecord::Base.turntable_connections.values
          klasses.each do |k|
            ActiveRecord::Base.connection_id = connection_id
            k.connection.clear_query_cache
            k.connection.disable_query_cache! unless enabled
          end
        end
      end
    end
  end
end