Function writeOpenMetricsSample

expfmt/openmetrics_create.go:397–453

writeOpenMetricsSample writes a single sample in OpenMetrics text format to w, given the metric name, the metric proto message itself, optionally an additional label name with a float64 value (use empty string as label name if not required), the value (optionally as float64 or uint64, determined by

(
	w enhancedWriter,
	name, suffix string,
	metric *dto.Metric,
	additionalLabelName string, additionalLabelValue float64,
	floatValue float64, intValue uint64, useIntValue bool,
	exemplar *dto.Exemplar,
)

// useIntValue), and optionally an exemplar (use nil if not required). The
// function returns the number of bytes written and any error encountered.
func writeOpenMetricsSample(
	w enhancedWriter,
	name, suffix string,
	metric *dto.Metric,
	additionalLabelName string, additionalLabelValue float64,
	floatValue float64, intValue uint64, useIntValue bool,
	exemplar *dto.Exemplar,
) (int, error) {
	written := 0
	n, err := writeOpenMetricsNameAndLabelPairs(
		w, name+suffix, metric.Label, additionalLabelName, additionalLabelValue,
	)
	written += n
	if err != nil {
		return written, err
	}
	err = w.WriteByte(' ')
	written++
	if err != nil {
		return written, err
	}
	if useIntValue {
		n, err = writeUint(w, intValue)
	} else {
		n, err = writeOpenMetricsFloat(w, floatValue)
	}
	written += n
	if err != nil {
		return written, err
	}
	if metric.TimestampMs != nil {
		err = w.WriteByte(' ')
		written++
		if err != nil {
			return written, err
		}
		// TODO(beorn7): Format this directly without converting to a float first.
		n, err = writeOpenMetricsFloat(w, float64(*metric.TimestampMs)/1000)
		written += n
		if err != nil {
			return written, err
		}
	}
	if exemplar != nil && len(exemplar.Label) > 0 {
		n, err = writeExemplar(w, exemplar)
		written += n
		if err != nil {
			return written, err
		}
	}
	err = w.WriteByte('\n')
	written++
	if err != nil {
		return written, err
	}
	return written, nil
}