func runTCPLatencyTest()

in client.go [297:354]
56 lines of code
11 McCabe index (conditional complexity)

func runTCPLatencyTest(test *ethrTest, g time.Duration, toStop chan int) {
	ui.printMsg("Running latency test: %v, %v", test.clientParam.RttCount, test.clientParam.BufferSize)
	conn, err := ethrDial(TCP, test.dialAddr)
	if err != nil {
		ui.printErr("Error dialing the latency connection: %v", err)
		return
	}
	defer conn.Close()
	err = handshakeWithServer(test, conn)
	if err != nil {
		ui.printErr("Failed in handshake with the server. Error: %v", err)
		return
	}
	ui.emitLatencyHdr()
	buffSize := test.clientParam.BufferSize
	buff := make([]byte, buffSize)
	for i := uint32(0); i < buffSize; i++ {
		buff[i] = byte(i)
	}
	blen := len(buff)
	rttCount := test.clientParam.RttCount
	latencyNumbers := make([]time.Duration, rttCount)
ExitForLoop:
	for {
	ExitSelect:
		select {
		case <-test.done:
			break ExitForLoop
		default:
			t0 := time.Now()
			for i := uint32(0); i < rttCount; i++ {
				s1 := time.Now()
				n, err := conn.Write(buff)
				if err != nil || n < blen {
					ui.printDbg("Error sending/receiving data on a connection for latency test: %v", err)
					toStop <- disconnect
					break ExitSelect
				}
				_, err = io.ReadFull(conn, buff)
				if err != nil {
					ui.printDbg("Error sending/receiving data on a connection for latency test: %v", err)
					toStop <- disconnect
					break ExitSelect
				}
				e2 := time.Since(s1)
				latencyNumbers[i] = e2
			}
			// TODO temp code, fix it better, this is to allow server to do
			// server side latency measurements as well.
			_, _ = conn.Write(buff)
			calcAndPrintLatency(test, rttCount, latencyNumbers)
			t1 := time.Since(t0)
			if t1 < g {
				time.Sleep(g - t1)
			}
		}
	}
}