func waitForSerialOutput()

in step_wait_for_instances_signal.go [151:235]
76 lines of code
25 McCabe index (conditional complexity)

func waitForSerialOutput(s *Step, project, zone, name string, so *SerialOutput, interval time.Duration) DError {
	w := s.w
	msg := fmt.Sprintf("Instance %q: watching serial port %d", name, so.Port)
	if so.SuccessMatch != "" {
		msg += fmt.Sprintf(", SuccessMatch: %q", so.SuccessMatch)
	}
	if len(so.FailureMatch) > 0 {
		msg += fmt.Sprintf(", FailureMatch: %q (this is not an error)", so.FailureMatch)
	}
	if so.StatusMatch != "" {
		msg += fmt.Sprintf(", StatusMatch: %q", so.StatusMatch)
	}
	w.LogStepInfo(s.name, "WaitForInstancesSignal", msg+".")
	var start int64
	var errs int
	tailString := ""
	tick := time.Tick(interval)
	for {
		select {
		case <-s.w.Cancel:
			return nil
		case <-tick:
			resp, err := w.ComputeClient.GetSerialPortOutput(project, zone, name, so.Port, start)
			if err != nil {
				status, sErr := w.ComputeClient.InstanceStatus(project, zone, name)
				if sErr != nil {
					err = fmt.Errorf("%v, error getting InstanceStatus: %v", err, sErr)
				} else {
					err = fmt.Errorf("%v, InstanceStatus: %q", err, status)
				}

				// Wait until machine restarts to evaluate SerialOutput.
				if status == "TERMINATED" || status == "STOPPED" || status == "STOPPING" {
					continue
				}

				// Retry up to 3 times in a row on any error if we successfully got InstanceStatus.
				if errs < 3 {
					errs++
					continue
				}

				return Errf("WaitForInstancesSignal: instance %q: error getting serial port: %v", name, err)
			}
			start = resp.Next
			lines := strings.Split(resp.Contents, "\n")
			for i, ln := range lines {
				// If there is a unconsumed tail string from the previous block of content, concat it with the 1st line of the new block of content.
				if i == 0 && tailString != "" {
					ln = tailString + ln
					tailString = ""
				}

				// If the content is not ended with a "\n", we want to store the last line as tail string, so it can be concat with the next block of content.
				if i == len(lines)-1 && lines[len(lines)-1] != "" {
					tailString = ln
					break
				}

				if so.StatusMatch != "" {
					if i := strings.Index(ln, so.StatusMatch); i != -1 {
						w.LogStepInfo(s.name, "WaitForInstancesSignal", "Instance %q: StatusMatch found: %q", name, strings.TrimSpace(ln[i:]))
						extractOutputValue(w, ln)
					}
				}
				if len(so.FailureMatch) > 0 {
					for _, failureMatch := range so.FailureMatch {
						if i := strings.Index(ln, failureMatch); i != -1 {
							errMsg := strings.TrimSpace(ln[i:])
							format := "WaitForInstancesSignal FailureMatch found for %q: %q"
							return newErr(errMsg, fmt.Errorf(format, name, errMsg))
						}
					}
				}
				if so.SuccessMatch != "" {
					if i := strings.Index(ln, so.SuccessMatch); i != -1 {
						w.LogStepInfo(s.name, "WaitForInstancesSignal", "Instance %q: SuccessMatch found %q", name, strings.TrimSpace(ln[i:]))
						return nil
					}
				}
			}
			errs = 0
		}
	}
}