instance method with_role_and_shard

# File activerecord/lib/active_record/connection_handling.rb, line 376
      def with_role_and_shard(role, shard, prevent_writes)
        prevent_writes = true if role == reading_role

        if ActiveRecord::Base.legacy_connection_handling
          with_handler(role.to_sym) do
            connection_handler.while_preventing_writes(prevent_writes) do
              self.connected_to_stack << { shard: shard, klasses: [self] }
              yield
            end
          end
        else
          self.connected_to_stack << { role: role, shard: shard, prevent_writes: prevent_writes, klasses: [self] }
          return_value = yield
          return_value.load if return_value.is_a? ActiveRecord::Relation
          return_value
        end
      ensure
        self.connected_to_stack.pop
      end