mirror of https://github.com/prometheus/prometheus
This reduces bulk and should avoid issues if a fix is made in one file and not the other. A few methods now call `Range()` instead of `range`, but nothing performance-sensitive. Signed-off-by: Bryan Boreham <bjboreham@gmail.com>pull/13159/head
Bryan Boreham
1 year ago
parent
f997c72f29
commit
a3e02f35d6
@ -0,0 +1,235 @@
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// Copyright 2017 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package labels
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import (
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"bytes"
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"encoding/json"
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"strconv"
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"github.com/prometheus/common/model"
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"golang.org/x/exp/slices"
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)
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const (
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MetricName = "__name__"
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AlertName = "alertname"
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BucketLabel = "le"
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InstanceName = "instance"
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labelSep = '\xfe'
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)
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var seps = []byte{'\xff'}
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// Label is a key/value pair of strings.
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type Label struct {
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Name, Value string
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}
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func (ls Labels) String() string {
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var b bytes.Buffer
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b.WriteByte('{')
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i := 0
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ls.Range(func(l Label) {
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if i > 0 {
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b.WriteByte(',')
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b.WriteByte(' ')
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}
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b.WriteString(l.Name)
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b.WriteByte('=')
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b.WriteString(strconv.Quote(l.Value))
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i++
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})
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b.WriteByte('}')
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return b.String()
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}
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// MarshalJSON implements json.Marshaler.
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func (ls Labels) MarshalJSON() ([]byte, error) {
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return json.Marshal(ls.Map())
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}
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// UnmarshalJSON implements json.Unmarshaler.
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func (ls *Labels) UnmarshalJSON(b []byte) error {
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var m map[string]string
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if err := json.Unmarshal(b, &m); err != nil {
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return err
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}
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*ls = FromMap(m)
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return nil
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}
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// MarshalYAML implements yaml.Marshaler.
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func (ls Labels) MarshalYAML() (interface{}, error) {
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return ls.Map(), nil
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}
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// UnmarshalYAML implements yaml.Unmarshaler.
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func (ls *Labels) UnmarshalYAML(unmarshal func(interface{}) error) error {
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var m map[string]string
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if err := unmarshal(&m); err != nil {
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return err
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}
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*ls = FromMap(m)
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return nil
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}
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// IsValid checks if the metric name or label names are valid.
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func (ls Labels) IsValid() bool {
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err := ls.Validate(func(l Label) error {
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if l.Name == model.MetricNameLabel && !model.IsValidMetricName(model.LabelValue(l.Value)) {
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return strconv.ErrSyntax
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}
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if !model.LabelName(l.Name).IsValid() || !model.LabelValue(l.Value).IsValid() {
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return strconv.ErrSyntax
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}
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return nil
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})
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return err == nil
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}
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// Map returns a string map of the labels.
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func (ls Labels) Map() map[string]string {
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m := make(map[string]string)
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ls.Range(func(l Label) {
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m[l.Name] = l.Value
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})
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return m
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}
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// FromMap returns new sorted Labels from the given map.
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func FromMap(m map[string]string) Labels {
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l := make([]Label, 0, len(m))
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for k, v := range m {
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l = append(l, Label{Name: k, Value: v})
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}
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return New(l...)
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}
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// Builder allows modifying Labels.
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type Builder struct {
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base Labels
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del []string
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add []Label
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}
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// NewBuilder returns a new LabelsBuilder.
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func NewBuilder(base Labels) *Builder {
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b := &Builder{
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del: make([]string, 0, 5),
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add: make([]Label, 0, 5),
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}
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b.Reset(base)
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return b
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}
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// Reset clears all current state for the builder.
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func (b *Builder) Reset(base Labels) {
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b.base = base
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b.del = b.del[:0]
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b.add = b.add[:0]
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b.base.Range(func(l Label) {
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if l.Value == "" {
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b.del = append(b.del, l.Name)
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}
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})
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}
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// Del deletes the label of the given name.
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func (b *Builder) Del(ns ...string) *Builder {
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for _, n := range ns {
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for i, a := range b.add {
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if a.Name == n {
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b.add = append(b.add[:i], b.add[i+1:]...)
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}
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}
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b.del = append(b.del, n)
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}
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return b
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}
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// Keep removes all labels from the base except those with the given names.
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func (b *Builder) Keep(ns ...string) *Builder {
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b.base.Range(func(l Label) {
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for _, n := range ns {
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if l.Name == n {
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return
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}
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}
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b.del = append(b.del, l.Name)
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})
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return b
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}
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// Set the name/value pair as a label. A value of "" means delete that label.
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func (b *Builder) Set(n, v string) *Builder {
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if v == "" {
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// Empty labels are the same as missing labels.
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return b.Del(n)
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}
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for i, a := range b.add {
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if a.Name == n {
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b.add[i].Value = v
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return b
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}
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}
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b.add = append(b.add, Label{Name: n, Value: v})
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return b
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}
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func (b *Builder) Get(n string) string {
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// Del() removes entries from .add but Set() does not remove from .del, so check .add first.
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for _, a := range b.add {
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if a.Name == n {
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return a.Value
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}
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}
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if slices.Contains(b.del, n) {
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return ""
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}
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return b.base.Get(n)
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}
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// Range calls f on each label in the Builder.
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func (b *Builder) Range(f func(l Label)) {
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// Stack-based arrays to avoid heap allocation in most cases.
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var addStack [128]Label
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var delStack [128]string
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// Take a copy of add and del, so they are unaffected by calls to Set() or Del().
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origAdd, origDel := append(addStack[:0], b.add...), append(delStack[:0], b.del...)
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b.base.Range(func(l Label) {
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if !slices.Contains(origDel, l.Name) && !contains(origAdd, l.Name) {
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f(l)
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}
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})
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for _, a := range origAdd {
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f(a)
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}
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}
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func contains(s []Label, n string) bool {
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for _, a := range s {
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if a.Name == n {
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return true
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}
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}
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return false
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}
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