Function writeNameAndLabelPairs

expfmt/text_create.go:354–457

writeNameAndLabelPairs converts a slice of LabelPair proto messages plus the explicitly given metric name and additional label pair into text formatted as required by the text format and writes it to 'w'. An empty slice in combination with an empty string 'additionalLabelName' results in nothing bei

(
	w enhancedWriter,
	name string,
	in []*dto.LabelPair,
	additionalLabelName string, additionalLabelValue float64,
)

// legacy-valid, it will be put inside the brackets as well. Legacy-invalid
// label names will also be quoted.
func writeNameAndLabelPairs(
	w enhancedWriter,
	name string,
	in []*dto.LabelPair,
	additionalLabelName string, additionalLabelValue float64,
) (int, error) {
	var (
		written            int
		separator          byte = '{'
		metricInsideBraces      = false
	)

	if name != "" {
		// If the name does not pass the legacy validity check, we must put the
		// metric name inside the braces.
		if !model.LegacyValidation.IsValidMetricName(name) {
			metricInsideBraces = true
			err := w.WriteByte(separator)
			written++
			if err != nil {
				return written, err
			}
			separator = ','
		}
		n, err := writeName(w, name)
		written += n
		if err != nil {
			return written, err
		}
	}

	if len(in) == 0 && additionalLabelName == "" {
		if metricInsideBraces {
			err := w.WriteByte('}')
			written++
			if err != nil {
				return written, err
			}
		}
		return written, nil
	}

	for _, lp := range in {
		err := w.WriteByte(separator)
		written++
		if err != nil {
			return written, err
		}
		n, err := writeName(w, lp.GetName())
		written += n
		if err != nil {
			return written, err
		}
		n, err = w.WriteString(`="`)
		written += n
		if err != nil {
			return written, err
		}