func srvrRunUDPPacketHandler()

in server.go [264:325]
50 lines of code
11 McCabe index (conditional complexity)

func srvrRunUDPPacketHandler(conn *net.UDPConn) {
	// This local map aids in efficiency to look up a test based on client's IP
	// address. We could use createOrGetTest but that takes a global lock.
	tests := make(map[string]*ethrTest)
	// For UDP, allocate buffer that can accomodate largest UDP datagram.
	readBuffer := make([]byte, 64*1024)
	n, remoteIP, err := 0, new(net.UDPAddr), error(nil)

	// This function handles UDP tests that came from clients that are no longer
	// sending any traffic. This is poor man's garbage collection to ensure the
	// server doesn't end up printing dormant client related statistics as UDP
	// has no reliable way to detect if client is active or not.
	go func() {
		for {
			time.Sleep(100 * time.Millisecond)
			for k, v := range tests {
				ui.printDbg("Found Test from server: %v, time: %v", k, v.lastAccess)
				// At 200ms of no activity, mark the test in-active so stats stop
				// printing.
				if time.Since(v.lastAccess) > (200 * time.Millisecond) {
					v.isDormant = true
				}
				// At 2s of no activity, delete the test by assuming that client
				// has stopped.
				if time.Since(v.lastAccess) > (2 * time.Second) {
					ui.printDbg("Deleting UDP test from server: %v, lastAccess: %v", k, v.lastAccess)
					safeDeleteTest(v)
					delete(tests, k)
				}
			}
		}
	}()
	for err == nil {
		n, remoteIP, err = conn.ReadFromUDP(readBuffer)
		if err != nil {
			ui.printDbg("Error receiving data from UDP for bandwidth test: %v", err)
			continue
		}
		ethrUnused(remoteIP)
		ethrUnused(n)
		server, port, _ := net.SplitHostPort(remoteIP.String())
		test, found := tests[server]
		if !found {
			test, isNew := createOrGetTest(server, UDP, All)
			if test != nil {
				tests[server] = test
			}
			if isNew {
				ui.printDbg("Creating UDP test from server: %v, lastAccess: %v", server, time.Now())
				ui.emitTestHdr()
			}
		}
		if test != nil {
			test.isDormant = false
			test.lastAccess = time.Now()
			atomic.AddUint64(&test.testResult.pps, 1)
			atomic.AddUint64(&test.testResult.bw, uint64(n))
		} else {
			ui.printDbg("Unable to create test for UDP traffic on port %s from %s port %s", gEthrPortStr, server, port)
		}
	}
}