func invokePingRequest()

in agent/heartbeat/heartbeat.go [87:177]
83 lines of code
15 McCabe index (conditional complexity)

func invokePingRequest(isHttpScheme bool, urlWithoutScheme string, willSwitchScheme bool) (response string, err error) {
	defer func() {
		errMsg := extractErrMsg(response)
		if errMsg != "" {
			log.GetLogger().Error("heart-beat: ", errMsg)
			if miss, fieldName, fieldType := checkFieldsdMissErr(errMsg); miss {
				_useFullFields.Store(true)
				log.GetLogger().Errorf("heart-beat request miss field[%s:%s] ", fieldName, fieldType)
				err = fmt.Errorf("request field missing")
			}
		}
	}()

	httpRequestURL := "http://" + urlWithoutScheme
	httpsRequestURL := "https://" + urlWithoutScheme
	var requestURL, switchedRequestUrl *string
	if isHttpScheme {
		requestURL = &httpRequestURL
		switchedRequestUrl = &httpsRequestURL
	} else {
		requestURL = &httpsRequestURL
		switchedRequestUrl = &httpRequestURL
	}
	err, response = util.HttpGet(*requestURL)
	if err != nil {
		tmp_err, ok := err.(*httpbase.StatusCodeError)
		if !(ok && tmp_err.StatusCode() < 500) {
			_retryMutex.Lock()
			defer _retryMutex.Unlock()
			Gap := time.Since(_startTime)
			//more than 1h than reset counter and start time.
			if Gap.Minutes() >= 60 {
				_retryCounter = 0
				_startTime = time.Now()
			}
			//less than 1h and counter more than 3.
			if _retryCounter >= 3 {
				log.GetLogger().WithFields(log.Fields{
					"requestURL": *requestURL,
					"response":   response,
				}).WithError(err).Errorln("Retry too frequent")
			} else {
				//do retry
				time.Sleep(3 * time.Second)
				_retryCounter++
				err, response = util.HttpGet(*requestURL)
				if err == nil {
					// Keep use current scheme next time
					if isHttpScheme {
						_tryHttp = true
					} else {
						_tryHttp = false
						_lastHttpFailedSendCounter = _sendCounter
					}
					return response, nil
				}
				log.GetLogger().WithFields(log.Fields{
					"requestURL": *requestURL,
					"response":   response,
				}).WithError(err).Errorln("Retry failed")
				if willSwitchScheme {
					err, response = util.HttpGet(*switchedRequestUrl)
					if err == nil {
						// Use another scheme next time
						if isHttpScheme {
							_tryHttp = false
							_lastHttpFailedSendCounter = _sendCounter
						} else {
							_tryHttp = true
						}
						return response, nil
					}
					log.GetLogger().WithFields(log.Fields{
						"switchedRequestURL": *switchedRequestUrl,
						"response":           response,
					}).WithError(err).Errorln("Retry failed with switched requestURL")
				}
			}
		}
		// Use another scheme next time
		if isHttpScheme {
			_tryHttp = false
			_lastHttpFailedSendCounter = _sendCounter
		} else {
			_tryHttp = true
		}

		return "", err
	}
	return response, nil
}