cloudflared-mirror/vendor/github.com/prometheus/common/model/metric.go

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// Copyright 2013 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 model
import (
"fmt"
"regexp"
"sort"
"strings"
"unicode/utf8"
dto "github.com/prometheus/client_model/go"
"google.golang.org/protobuf/proto"
)
var (
// NameValidationScheme determines the method of name validation to be used by
// all calls to IsValidMetricName() and LabelName IsValid(). Setting UTF-8 mode
// in isolation from other components that don't support UTF-8 may result in
// bugs or other undefined behavior. This value is intended to be set by
// UTF-8-aware binaries as part of their startup. To avoid need for locking,
// this value should be set once, ideally in an init(), before multiple
// goroutines are started.
NameValidationScheme = LegacyValidation
// NameEscapingScheme defines the default way that names will be
// escaped when presented to systems that do not support UTF-8 names. If the
// Content-Type "escaping" term is specified, that will override this value.
NameEscapingScheme = ValueEncodingEscaping
)
// ValidationScheme is a Go enum for determining how metric and label names will
// be validated by this library.
type ValidationScheme int
const (
// LegacyValidation is a setting that requirets that metric and label names
// conform to the original Prometheus character requirements described by
// MetricNameRE and LabelNameRE.
LegacyValidation ValidationScheme = iota
// UTF8Validation only requires that metric and label names be valid UTF-8
// strings.
UTF8Validation
)
type EscapingScheme int
const (
// NoEscaping indicates that a name will not be escaped. Unescaped names that
// do not conform to the legacy validity check will use a new exposition
// format syntax that will be officially standardized in future versions.
NoEscaping EscapingScheme = iota
// UnderscoreEscaping replaces all legacy-invalid characters with underscores.
UnderscoreEscaping
// DotsEscaping is similar to UnderscoreEscaping, except that dots are
// converted to `_dot_` and pre-existing underscores are converted to `__`.
DotsEscaping
// ValueEncodingEscaping prepends the name with `U__` and replaces all invalid
// characters with the unicode value, surrounded by underscores. Single
// underscores are replaced with double underscores.
ValueEncodingEscaping
)
const (
// EscapingKey is the key in an Accept or Content-Type header that defines how
// metric and label names that do not conform to the legacy character
// requirements should be escaped when being scraped by a legacy prometheus
// system. If a system does not explicitly pass an escaping parameter in the
// Accept header, the default NameEscapingScheme will be used.
EscapingKey = "escaping"
// Possible values for Escaping Key:
AllowUTF8 = "allow-utf-8" // No escaping required.
EscapeUnderscores = "underscores"
EscapeDots = "dots"
EscapeValues = "values"
)
// MetricNameRE is a regular expression matching valid metric
// names. Note that the IsValidMetricName function performs the same
// check but faster than a match with this regular expression.
var MetricNameRE = regexp.MustCompile(`^[a-zA-Z_:][a-zA-Z0-9_:]*$`)
// A Metric is similar to a LabelSet, but the key difference is that a Metric is
// a singleton and refers to one and only one stream of samples.
type Metric LabelSet
// Equal compares the metrics.
func (m Metric) Equal(o Metric) bool {
return LabelSet(m).Equal(LabelSet(o))
}
// Before compares the metrics' underlying label sets.
func (m Metric) Before(o Metric) bool {
return LabelSet(m).Before(LabelSet(o))
}
// Clone returns a copy of the Metric.
func (m Metric) Clone() Metric {
clone := make(Metric, len(m))
for k, v := range m {
clone[k] = v
}
return clone
}
func (m Metric) String() string {
metricName, hasName := m[MetricNameLabel]
numLabels := len(m) - 1
if !hasName {
numLabels = len(m)
}
labelStrings := make([]string, 0, numLabels)
for label, value := range m {
if label != MetricNameLabel {
labelStrings = append(labelStrings, fmt.Sprintf("%s=%q", label, value))
}
}
switch numLabels {
case 0:
if hasName {
return string(metricName)
}
return "{}"
default:
sort.Strings(labelStrings)
return fmt.Sprintf("%s{%s}", metricName, strings.Join(labelStrings, ", "))
}
}
// Fingerprint returns a Metric's Fingerprint.
func (m Metric) Fingerprint() Fingerprint {
return LabelSet(m).Fingerprint()
}
// FastFingerprint returns a Metric's Fingerprint calculated by a faster hashing
// algorithm, which is, however, more susceptible to hash collisions.
func (m Metric) FastFingerprint() Fingerprint {
return LabelSet(m).FastFingerprint()
}
// IsValidMetricName returns true iff name matches the pattern of MetricNameRE
// for legacy names, and iff it's valid UTF-8 if the UTF8Validation scheme is
// selected.
func IsValidMetricName(n LabelValue) bool {
switch NameValidationScheme {
case LegacyValidation:
return IsValidLegacyMetricName(n)
case UTF8Validation:
if len(n) == 0 {
return false
}
return utf8.ValidString(string(n))
default:
panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
}
}
// IsValidLegacyMetricName is similar to IsValidMetricName but always uses the
// legacy validation scheme regardless of the value of NameValidationScheme.
// This function, however, does not use MetricNameRE for the check but a much
// faster hardcoded implementation.
func IsValidLegacyMetricName(n LabelValue) bool {
if len(n) == 0 {
return false
}
for i, b := range n {
if !isValidLegacyRune(b, i) {
return false
}
}
return true
}
// EscapeMetricFamily escapes the given metric names and labels with the given
// escaping scheme. Returns a new object that uses the same pointers to fields
// when possible and creates new escaped versions so as not to mutate the
// input.
func EscapeMetricFamily(v *dto.MetricFamily, scheme EscapingScheme) *dto.MetricFamily {
if v == nil {
return nil
}
if scheme == NoEscaping {
return v
}
out := &dto.MetricFamily{
Help: v.Help,
Type: v.Type,
}
// If the name is nil, copy as-is, don't try to escape.
if v.Name == nil || IsValidLegacyMetricName(LabelValue(v.GetName())) {
out.Name = v.Name
} else {
out.Name = proto.String(EscapeName(v.GetName(), scheme))
}
for _, m := range v.Metric {
if !metricNeedsEscaping(m) {
out.Metric = append(out.Metric, m)
continue
}
escaped := &dto.Metric{
Gauge: m.Gauge,
Counter: m.Counter,
Summary: m.Summary,
Untyped: m.Untyped,
Histogram: m.Histogram,
TimestampMs: m.TimestampMs,
}
for _, l := range m.Label {
if l.GetName() == MetricNameLabel {
if l.Value == nil || IsValidLegacyMetricName(LabelValue(l.GetValue())) {
escaped.Label = append(escaped.Label, l)
continue
}
escaped.Label = append(escaped.Label, &dto.LabelPair{
Name: proto.String(MetricNameLabel),
Value: proto.String(EscapeName(l.GetValue(), scheme)),
})
continue
}
if l.Name == nil || IsValidLegacyMetricName(LabelValue(l.GetName())) {
escaped.Label = append(escaped.Label, l)
continue
}
escaped.Label = append(escaped.Label, &dto.LabelPair{
Name: proto.String(EscapeName(l.GetName(), scheme)),
Value: l.Value,
})
}
out.Metric = append(out.Metric, escaped)
}
return out
}
func metricNeedsEscaping(m *dto.Metric) bool {
for _, l := range m.Label {
if l.GetName() == MetricNameLabel && !IsValidLegacyMetricName(LabelValue(l.GetValue())) {
return true
}
if !IsValidLegacyMetricName(LabelValue(l.GetName())) {
return true
}
}
return false
}
const (
lowerhex = "0123456789abcdef"
)
// EscapeName escapes the incoming name according to the provided escaping
// scheme. Depending on the rules of escaping, this may cause no change in the
// string that is returned. (Especially NoEscaping, which by definition is a
// noop). This function does not do any validation of the name.
func EscapeName(name string, scheme EscapingScheme) string {
if len(name) == 0 {
return name
}
var escaped strings.Builder
switch scheme {
case NoEscaping:
return name
case UnderscoreEscaping:
if IsValidLegacyMetricName(LabelValue(name)) {
return name
}
for i, b := range name {
if isValidLegacyRune(b, i) {
escaped.WriteRune(b)
} else {
escaped.WriteRune('_')
}
}
return escaped.String()
case DotsEscaping:
// Do not early return for legacy valid names, we still escape underscores.
for i, b := range name {
if b == '_' {
escaped.WriteString("__")
} else if b == '.' {
escaped.WriteString("_dot_")
} else if isValidLegacyRune(b, i) {
escaped.WriteRune(b)
} else {
escaped.WriteRune('_')
}
}
return escaped.String()
case ValueEncodingEscaping:
if IsValidLegacyMetricName(LabelValue(name)) {
return name
}
escaped.WriteString("U__")
for i, b := range name {
if isValidLegacyRune(b, i) {
escaped.WriteRune(b)
} else if !utf8.ValidRune(b) {
escaped.WriteString("_FFFD_")
} else if b < 0x100 {
escaped.WriteRune('_')
for s := 4; s >= 0; s -= 4 {
escaped.WriteByte(lowerhex[b>>uint(s)&0xF])
}
escaped.WriteRune('_')
} else if b < 0x10000 {
escaped.WriteRune('_')
for s := 12; s >= 0; s -= 4 {
escaped.WriteByte(lowerhex[b>>uint(s)&0xF])
}
escaped.WriteRune('_')
}
}
return escaped.String()
default:
panic(fmt.Sprintf("invalid escaping scheme %d", scheme))
}
}
// lower function taken from strconv.atoi
func lower(c byte) byte {
return c | ('x' - 'X')
}
// UnescapeName unescapes the incoming name according to the provided escaping
// scheme if possible. Some schemes are partially or totally non-roundtripable.
// If any error is enountered, returns the original input.
func UnescapeName(name string, scheme EscapingScheme) string {
if len(name) == 0 {
return name
}
switch scheme {
case NoEscaping:
return name
case UnderscoreEscaping:
// It is not possible to unescape from underscore replacement.
return name
case DotsEscaping:
name = strings.ReplaceAll(name, "_dot_", ".")
name = strings.ReplaceAll(name, "__", "_")
return name
case ValueEncodingEscaping:
escapedName, found := strings.CutPrefix(name, "U__")
if !found {
return name
}
var unescaped strings.Builder
TOP:
for i := 0; i < len(escapedName); i++ {
// All non-underscores are treated normally.
if escapedName[i] != '_' {
unescaped.WriteByte(escapedName[i])
continue
}
i++
if i >= len(escapedName) {
return name
}
// A double underscore is a single underscore.
if escapedName[i] == '_' {
unescaped.WriteByte('_')
continue
}
// We think we are in a UTF-8 code, process it.
var utf8Val uint
for j := 0; i < len(escapedName); j++ {
// This is too many characters for a utf8 value.
if j > 4 {
return name
}
// Found a closing underscore, convert to a rune, check validity, and append.
if escapedName[i] == '_' {
utf8Rune := rune(utf8Val)
if !utf8.ValidRune(utf8Rune) {
return name
}
unescaped.WriteRune(utf8Rune)
continue TOP
}
r := lower(escapedName[i])
utf8Val *= 16
if r >= '0' && r <= '9' {
utf8Val += uint(r) - '0'
} else if r >= 'a' && r <= 'f' {
utf8Val += uint(r) - 'a' + 10
} else {
return name
}
i++
}
// Didn't find closing underscore, invalid.
return name
}
return unescaped.String()
default:
panic(fmt.Sprintf("invalid escaping scheme %d", scheme))
}
}
func isValidLegacyRune(b rune, i int) bool {
return (b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || b == ':' || (b >= '0' && b <= '9' && i > 0)
}
func (e EscapingScheme) String() string {
switch e {
case NoEscaping:
return AllowUTF8
case UnderscoreEscaping:
return EscapeUnderscores
case DotsEscaping:
return EscapeDots
case ValueEncodingEscaping:
return EscapeValues
default:
panic(fmt.Sprintf("unknown format scheme %d", e))
}
}
func ToEscapingScheme(s string) (EscapingScheme, error) {
if s == "" {
return NoEscaping, fmt.Errorf("got empty string instead of escaping scheme")
}
switch s {
case AllowUTF8:
return NoEscaping, nil
case EscapeUnderscores:
return UnderscoreEscaping, nil
case EscapeDots:
return DotsEscaping, nil
case EscapeValues:
return ValueEncodingEscaping, nil
default:
return NoEscaping, fmt.Errorf("unknown format scheme " + s)
}
}