    # File lib/phusion_passenger/analytics_logger.rb, line 118
                    def close(flush_to_disk = false)
                            @connection.synchronize do
                                    begin
                                            # We need an ACK here. See abstract_request_handler.rb finalize_request.
                                            @connection.channel.write("closeTransaction", @txn_id,
                                                    AnalyticsLogger.timestamp_string, true)
                                            result = @connection.channel.read
                                            if result != ["ok"]
                                                    raise "Expected logging agent to respond with 'ok', but got #{result.inspect} instead"
                                            end
                                            if flush_to_disk
                                                    @connection.channel.write("flush")
                                                    result = @connection.channel.read
                                                    if result != ["ok"]
                                                            raise "Invalid logging agent response #{result.inspect} to the 'flush' command"
                                                    end
                                            end
                                    rescue SystemCallError, IOError => e
                                            @connection.disconnect
                                            DebugLogging.warn("Error communicating with the logging agent: #{e.message}")
                                    rescue Exception => e
                                            @connection.disconnect
                                            raise e
                                    ensure
                                            @connection.unref
                                            @connection = nil
                                    end
                            end if @connection
                    end