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// Copyright 2014 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package expfmt
import (
"bufio"
"fmt"
"io"
"io/ioutil"
"math"
"strconv"
"strings"
"sync"
"github.com/prometheus/common/model"
dto "github.com/prometheus/client_model/go"
)
// enhancedWriter has all the enhanced write functions needed here. bufio.Writer
// implements it.
type enhancedWriter interface {
io.Writer
WriteRune(r rune) (n int, err error)
WriteString(s string) (n int, err error)
WriteByte(c byte) error
}
const (
initialNumBufSize = 24
)
var (
bufPool = sync.Pool{
New: func() interface{} {
return bufio.NewWriter(ioutil.Discard)
},
}
numBufPool = sync.Pool{
New: func() interface{} {
b := make([]byte, 0, initialNumBufSize)
return &b
},
}
)
// 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.
//
// This method fulfills the type 'prometheus.encoder'.
func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err error) {
// Fail-fast checks.
if len(in.Metric) == 0 {
return 0, fmt.Errorf("MetricFamily has no metrics: %s", in)
}
name := in.GetName()
if name == "" {
return 0, fmt.Errorf("MetricFamily has no name: %s", in)
}
// Try the interface upgrade. If it doesn't work, we'll use a
// bufio.Writer from the sync.Pool.
w, ok := out.(enhancedWriter)
if !ok {
b := bufPool.Get().(*bufio.Writer)
b.Reset(out)
w = b
defer func() {
bErr := b.Flush()
if err == nil {
err = bErr
}
bufPool.Put(b)
}()
}
var n int
// Comments, first HELP, then TYPE.
if in.Help != nil {
n, err = w.WriteString("# HELP ")
written += n
if err != nil {
return
}
n, err = w.WriteString(name)
written += n
if err != nil {
return
}
err = w.WriteByte(' ')
written++
if err != nil {
return
}
n, err = writeEscapedString(w, *in.Help, false)
written += n
if err != nil {
return
}
err = w.WriteByte('\n')
written++
if err != nil {
return
}
}
n, err = w.WriteString("# TYPE ")
written += n
if err != nil {
return
}
n, err = w.WriteString(name)
written += n
if err != nil {
return
}
metricType := in.GetType()
switch metricType {
case dto.MetricType_COUNTER:
n, err = w.WriteString(" counter\n")
case dto.MetricType_GAUGE:
n, err = w.WriteString(" gauge\n")
case dto.MetricType_SUMMARY:
n, err = w.WriteString(" summary\n")
case dto.MetricType_UNTYPED:
n, err = w.WriteString(" untyped\n")
case dto.MetricType_HISTOGRAM:
n, err = w.WriteString(" histogram\n")
default:
return written, fmt.Errorf("unknown metric type %s", metricType.String())
}
written += n
if err != nil {
return
}
// Finally the samples, one line for each.
for _, metric := range in.Metric {
switch metricType {
case dto.MetricType_COUNTER:
if metric.Counter == nil {
return written, fmt.Errorf(
"expected counter in metric %s %s", name, metric,
)
}
n, err = writeSample(
w, name, "", metric, "", 0,
metric.Counter.GetValue(),
)
case dto.MetricType_GAUGE:
if metric.Gauge == nil {
return written, fmt.Errorf(
"expected gauge in metric %s %s", name, metric,
)
}
n, err = writeSample(
w, name, "", metric, "", 0,
metric.Gauge.GetValue(),
)
case dto.MetricType_UNTYPED:
if metric.Untyped == nil {
return written, fmt.Errorf(
"expected untyped in metric %s %s", name, metric,
)
}
n, err = writeSample(
w, name, "", metric, "", 0,
metric.Untyped.GetValue(),
)
case dto.MetricType_SUMMARY:
if metric.Summary == nil {
return written, fmt.Errorf(
"expected summary in metric %s %s", name, metric,
)
}
for _, q := range metric.Summary.Quantile {
n, err = writeSample(
w, name, "", metric,
model.QuantileLabel, q.GetQuantile(),
q.GetValue(),
)
written += n
if err != nil {
return
}
}
n, err = writeSample(
w, name, "_sum", metric, "", 0,
metric.Summary.GetSampleSum(),
)
written += n
if err != nil {
return
}
n, err = writeSample(
w, name, "_count", metric, "", 0,
float64(metric.Summary.GetSampleCount()),
)
case dto.MetricType_HISTOGRAM:
if metric.Histogram == nil {
return written, fmt.Errorf(
"expected histogram in metric %s %s", name, metric,
)
}
infSeen := false
for _, b := range metric.Histogram.Bucket {
n, err = writeSample(
w, name, "_bucket", metric,
model.BucketLabel, b.GetUpperBound(),
float64(b.GetCumulativeCount()),
)
written += n
if err != nil {
return
}
if math.IsInf(b.GetUpperBound(), +1) {
infSeen = true
}
}
if !infSeen {
n, err = writeSample(
w, name, "_bucket", metric,
model.BucketLabel, math.Inf(+1),
float64(metric.Histogram.GetSampleCount()),
)
written += n
if err != nil {
return
}
}
n, err = writeSample(
w, name, "_sum", metric, "", 0,
metric.Histogram.GetSampleSum(),
)
written += n
if err != nil {
return
}
n, err = writeSample(
w, name, "_count", metric, "", 0,
float64(metric.Histogram.GetSampleCount()),
)
default:
return written, fmt.Errorf(
"unexpected type in metric %s %s", name, metric,
)
}
written += n
if err != nil {
return
}
}
return
}
// 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) {
var written int
n, err := w.WriteString(name)
written += n
if err != nil {
return written, err
}
if suffix != "" {
n, err = w.WriteString(suffix)
written += n
if err != nil {
return written, err
}
}
n, err = writeLabelPairs(
w, metric.Label, additionalLabelName, additionalLabelValue,
)
written += n
if err != nil {
return written, err
}
err = w.WriteByte(' ')
written++
if err != nil {
return written, err
}
n, err = writeFloat(w, value)
written += n
if err != nil {
return written, err
}
if metric.TimestampMs != nil {
err = w.WriteByte(' ')
written++
if err != nil {
return written, err
}
n, err = writeInt(w, *metric.TimestampMs)
written += n
if err != nil {
return written, err
}
}
err = w.WriteByte('\n')
written++
if err != nil {
return written, err
}
return written, nil
}
// writeLabelPairs converts a slice of LabelPair proto messages plus the
// explicitly given 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.
func writeLabelPairs(
w enhancedWriter,
in []*dto.LabelPair,
additionalLabelName string, additionalLabelValue float64,
) (int, error) {
if len(in) == 0 && additionalLabelName == "" {
return 0, nil
}
var (
written int
separator byte = '{'
)
for _, lp := range in {
err := w.WriteByte(separator)
written++
if err != nil {
return written, err
}
n, err := w.WriteString(lp.GetName())
written += n
if err != nil {
return written, err
}
n, err = w.WriteString(`="`)
written += n
if err != nil {
return written, err
}
n, err = writeEscapedString(w, lp.GetValue(), true)
written += n
if err != nil {
return written, err
}
err = w.WriteByte('"')
written++
if err != nil {
return written, err
}
separator = ','
}
if additionalLabelName != "" {
err := w.WriteByte(separator)
written++
if err != nil {
return written, err
}
n, err := w.WriteString(additionalLabelName)
written += n
if err != nil {
return written, err
}
n, err = w.WriteString(`="`)
written += n
if err != nil {
return written, err
}
n, err = writeFloat(w, additionalLabelValue)
written += n
if err != nil {
return written, err
}
err = w.WriteByte('"')
written++
if err != nil {
return written, err
}
}
err := w.WriteByte('}')
written++
if err != nil {
return written, err
}
return written, nil
}
// writeEscapedString replaces '\' by '\\', new line character by '\n', and - if
// includeDoubleQuote is true - '"' by '\"'.
var (
escaper = strings.NewReplacer("\\", `\\`, "\n", `\n`)
quotedEscaper = strings.NewReplacer("\\", `\\`, "\n", `\n`, "\"", `\"`)
)
func writeEscapedString(w enhancedWriter, v string, includeDoubleQuote bool) (int, error) {
if includeDoubleQuote {
return quotedEscaper.WriteString(w, v)
}
return escaper.WriteString(w, v)
}
// 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) {
switch {
case f == 1:
return 1, w.WriteByte('1')
case f == 0:
return 1, w.WriteByte('0')
case f == -1:
return w.WriteString("-1")
case math.IsNaN(f):
return w.WriteString("NaN")
case math.IsInf(f, +1):
return w.WriteString("+Inf")
case math.IsInf(f, -1):
return w.WriteString("-Inf")
default:
bp := numBufPool.Get().(*[]byte)
*bp = strconv.AppendFloat((*bp)[:0], f, 'g', -1, 64)
written, err := w.Write(*bp)
numBufPool.Put(bp)
return written, err
}
}
// 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) {
bp := numBufPool.Get().(*[]byte)
*bp = strconv.AppendInt((*bp)[:0], i, 10)
written, err := w.Write(*bp)
numBufPool.Put(bp)
return written, err
}
