kubernetes/vendor/github.com/prometheus/common/expfmt/text_create.go

type enhancedWriter …

const initialNumBufSize …

var bufPool …

var numBufPool …

// MetricFamilyToText converts a MetricFamily proto message into text format and
// writes the resulting lines to 'out'. It returns the number of bytes written
// and any error encountered. The output will have the same order as the input,
// no further sorting is performed. Furthermore, this function assumes the input
// is already sanitized and does not perform any sanity checks. If the input
// contains duplicate metrics or invalid metric or label names, the conversion
// will result in invalid text format output.
//
// If metric names conform to the legacy validation pattern, they will be placed
// outside the brackets in the traditional way, like `foo{}`. If the metric name
// fails the legacy validation check, it will be placed quoted inside the
// brackets: `{"foo"}`. As stated above, the input is assumed to be santized and
// no error will be thrown in this case.
//
// Similar to metric names, if label names conform to the legacy validation
// pattern, they will be unquoted as normal, like `foo{bar="baz"}`. If the label
// name fails the legacy validation check, it will be quoted:
// `foo{"bar"="baz"}`. As stated above, the input is assumed to be santized and
// no error will be thrown in this case.
//
// This method fulfills the type 'prometheus.encoder'.
func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err error) { … }

// writeSample writes a single sample in 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), and
// the value. The function returns the number of bytes written and any error
// encountered.
func writeSample(
	w enhancedWriter,
	name, suffix string,
	metric *dto.Metric,
	additionalLabelName string, additionalLabelValue float64,
	value float64,
) (int, error) { … }

// 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
// being written. Otherwise, the label pairs are written, escaped as required by
// the text format, and enclosed in '{...}'. The function returns the number of
// bytes written and any error encountered. If the metric name is not
// 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 escaper …

var quotedEscaper …

func writeEscapedString(w enhancedWriter, v string, includeDoubleQuote bool) (int, error) { … }

// writeFloat is equivalent to fmt.Fprint with a float64 argument but hardcodes
// a few common cases for increased efficiency. For non-hardcoded cases, it uses
// strconv.AppendFloat to avoid allocations, similar to writeInt.
func writeFloat(w enhancedWriter, f float64) (int, error) { … }

// writeInt is equivalent to fmt.Fprint with an int64 argument but uses
// strconv.AppendInt with a byte slice taken from a sync.Pool to avoid
// allocations.
func writeInt(w enhancedWriter, i int64) (int, error) { … }

// writeName writes a string as-is if it complies with the legacy naming
// scheme, or escapes it in double quotes if not.
func writeName(w enhancedWriter, name string) (int, error) { … }