func()

in ptp/ptp4u/server/server.go [56:157]
81 lines of code
15 McCabe index (conditional complexity)

func (s *Server) Start() error {
	// Set clock identity
	iface, err := net.InterfaceByName(s.Config.Interface)
	if err != nil {
		return fmt.Errorf("unable to get mac address of the interface: %v", err)
	}
	s.Config.clockIdentity, err = ptp.NewClockIdentity(iface.HardwareAddr)
	if err != nil {
		return fmt.Errorf("unable to get the Clock Identity (EUI-64 address) of the interface: %v", err)
	}

	// initialize the context for the subscriptions
	s.ctx, s.cancel = context.WithCancel(context.Background())

	// Call wg.Add(1) ONLY once
	// If ANY goroutine finishes no matter how many of them we run
	// wg.Done will unblock
	var wg sync.WaitGroup
	wg.Add(1)

	// start X workers
	s.sw = make([]*sendWorker, s.Config.SendWorkers)
	for i := 0; i < s.Config.SendWorkers; i++ {
		// Each worker to monitor own queue
		s.sw[i] = newSendWorker(i, s.Config, s.Stats)
		go func(i int) {
			defer wg.Done()
			s.sw[i].Start()
		}(i)
	}

	go func() {
		defer wg.Done()
		s.startGeneralListener()
	}()
	go func() {
		defer wg.Done()
		s.startEventListener()
	}()

	// Run active metric reporting
	go func() {
		defer wg.Done()
		for {
			<-time.After(s.Config.MetricInterval)
			for _, w := range s.sw {
				w.inventoryClients()
			}
			s.Stats.SetUTCOffset(int64(s.Config.UTCOffset.Seconds()))

			s.Stats.Snapshot()
			s.Stats.Reset()
		}
	}()

	// Drain check
	go func() {
		defer wg.Done()
		ticker := time.NewTicker(s.Config.DrainInterval)
		defer ticker.Stop()
		for ; true; <-ticker.C {
			var drain bool
			for _, check := range s.Checks {
				if check.Check() {
					drain = true
					log.Warningf("%T engaged shifting traffic", check)
					break
				}
			}

			if drain {
				s.Drain()
				s.Stats.SetDrain(1)
			} else {
				s.Undrain()
				s.Stats.SetDrain(0)
			}
		}
	}()

	// Update UTC offset periodically
	go func() {
		defer wg.Done()
		for {
			<-time.After(1 * time.Minute)
			if s.Config.Leapsectz {
				if err := s.Config.SetUTCOffsetFromLeapsectz(); err != nil {
					log.Errorf("Failed to update UTC offset: %v. Keeping the last known: %s", err, s.Config.UTCOffset)
				}
			} else if s.Config.SHM {
				if err := s.Config.SetUTCOffsetFromSHM(); err != nil {
					log.Errorf("Failed to update UTC offset: %v. Keeping the last known: %s", err, s.Config.UTCOffset)
				}
			}
			log.Debugf("UTC offset is: %v", s.Config.UTCOffset.Seconds())
		}
	}()

	// Wait for ANY gorouine to finish
	wg.Wait()
	return fmt.Errorf("one of server routines finished")
}