lookup_connection_handler

# File activerecord/lib/active_record/connection_handling.rb, line 259
    def lookup_connection_handler(handler_key) # :nodoc:
      if ActiveRecord::Base.legacy_connection_handling
        handler_key ||= ActiveRecord::Base.writing_role
        connection_handlers[handler_key] ||= ActiveRecord::ConnectionAdapters::ConnectionHandler.new
      else
        ActiveRecord::Base.connection_handler
      end
    end