circonus-gometrics.go
func New(cfg *Config) (*CirconusMetrics, error) {

	if cfg == nil {
		return nil, errors.New("invalid configuration (nil)")
	}

	cm := &CirconusMetrics{
		counters:     make(map[string]uint64),
		counterFuncs: make(map[string]func() uint64),
		gauges:       make(map[string]interface{}),
		gaugeFuncs:   make(map[string]func() int64),
		histograms:   make(map[string]*Histogram),
		text:         make(map[string]string),
		textFuncs:    make(map[string]func() string),
		lastMetrics:  &prevMetrics{},
	}

	// Logging
	{
		cm.Debug = cfg.Debug
		cm.Log = cfg.Log

		if cm.Debug && cm.Log == nil {
			cm.Log = log.New(os.Stderr, "", log.LstdFlags)
		}
		if cm.Log == nil {
			cm.Log = log.New(ioutil.Discard, "", log.LstdFlags)
		}
	}

	// Flush Interval
	{
		fi := defaultFlushInterval
		if cfg.Interval != "" {
			fi = cfg.Interval
		}

		dur, err := time.ParseDuration(fi)
		if err != nil {
			return nil, errors.Wrap(err, "parsing flush interval")
		}
		cm.flushInterval = dur
	}

	// metric resets

	cm.resetCounters = true
	if cfg.ResetCounters != "" {
		setting, err := strconv.ParseBool(cfg.ResetCounters)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset counters")
		}
		cm.resetCounters = setting
	}

	cm.resetGauges = true
	if cfg.ResetGauges != "" {
		setting, err := strconv.ParseBool(cfg.ResetGauges)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset gauges")
		}
		cm.resetGauges = setting
	}

	cm.resetHistograms = true
	if cfg.ResetHistograms != "" {
		setting, err := strconv.ParseBool(cfg.ResetHistograms)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset histograms")
		}
		cm.resetHistograms = setting
	}

	cm.resetText = true
	if cfg.ResetText != "" {
		setting, err := strconv.ParseBool(cfg.ResetText)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset text")
		}
		cm.resetText = setting
	}

	// check manager
	{
		cfg.CheckManager.Debug = cm.Debug
		cfg.CheckManager.Log = cm.Log

		check, err := checkmgr.New(&cfg.CheckManager)
		if err != nil {
			return nil, errors.Wrap(err, "creating new check manager")
		}
		cm.check = check
	}

	// start background initialization
	cm.check.Initialize()

	// if automatic flush is enabled, start it.
	// NOTE: submit will jettison metrics until initialization has completed.
	if cm.flushInterval > time.Duration(0) {
		go func() {
			for range time.NewTicker(cm.flushInterval).C {
				cm.Flush()
			}
		}()
	}

	return cm, nil
}
func New(cfg *Config) (*CirconusMetrics, error) {

	if cfg == nil {
		return nil, errors.New("invalid configuration (nil)")
	}

	cm := &CirconusMetrics{
		counters:     make(map[string]uint64),
		counterFuncs: make(map[string]func() uint64),
		gauges:       make(map[string]interface{}),
		gaugeFuncs:   make(map[string]func() int64),
		histograms:   make(map[string]*Histogram),
		text:         make(map[string]string),
		textFuncs:    make(map[string]func() string),
		lastMetrics:  &prevMetrics{},
	}

	// Logging
	{
		cm.Debug = cfg.Debug
		cm.Log = cfg.Log

		if cm.Debug && cm.Log == nil {
			cm.Log = log.New(os.Stderr, "", log.LstdFlags)
		}
		if cm.Log == nil {
			cm.Log = log.New(ioutil.Discard, "", log.LstdFlags)
		}
	}

	// Flush Interval
	{
		fi := defaultFlushInterval
		if cfg.Interval != "" {
			fi = cfg.Interval
		}

		dur, err := time.ParseDuration(fi)
		if err != nil {
			return nil, errors.Wrap(err, "parsing flush interval")
		}
		cm.flushInterval = dur
	}

	// metric resets

	cm.resetCounters = true
	if cfg.ResetCounters != "" {
		setting, err := strconv.ParseBool(cfg.ResetCounters)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset counters")
		}
		cm.resetCounters = setting
	}

	cm.resetGauges = true
	if cfg.ResetGauges != "" {
		setting, err := strconv.ParseBool(cfg.ResetGauges)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset gauges")
		}
		cm.resetGauges = setting
	}

	cm.resetHistograms = true
	if cfg.ResetHistograms != "" {
		setting, err := strconv.ParseBool(cfg.ResetHistograms)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset histograms")
		}
		cm.resetHistograms = setting
	}

	cm.resetText = true
	if cfg.ResetText != "" {
		setting, err := strconv.ParseBool(cfg.ResetText)
		if err != nil {
			return nil, errors.Wrap(err, "parsing reset text")
		}
		cm.resetText = setting
	}

	// check manager
	{
		cfg.CheckManager.Debug = cm.Debug
		cfg.CheckManager.Log = cm.Log

		check, err := checkmgr.New(&cfg.CheckManager)
		if err != nil {
			return nil, errors.Wrap(err, "creating new check manager")
		}
		cm.check = check
	}

	// start background initialization
	cm.check.Initialize()

	// if automatic flush is enabled, start it.
	// NOTE: submit will jettison metrics until initialization has completed.
	if cm.flushInterval > time.Duration(0) {
		go func() {
			for range time.NewTicker(cm.flushInterval).C {
				cm.Flush()
			}
		}()
	}

	return cm, nil
}
// New returns a CirconusMetrics instance