# File lib/mongo/cluster.rb, line 548
    def update_cluster_time(result)
      if cluster_time_doc = result.cluster_time
        @cluster_time_lock.synchronize do
          if @cluster_time.nil?
            @cluster_time = cluster_time_doc
          elsif cluster_time_doc[CLUSTER_TIME] > @cluster_time[CLUSTER_TIME]
            @cluster_time = cluster_time_doc
          end
        end
      end
    end