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- // Copyright 2018 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 prometheus
-
- import (
- "errors"
- "fmt"
- "strings"
- "unicode/utf8"
-
- "github.com/prometheus/common/model"
- )
-
- // Labels represents a collection of label name -> value mappings. This type is
- // commonly used with the With(Labels) and GetMetricWith(Labels) methods of
- // metric vector Collectors, e.g.:
- //
- // myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
- //
- // The other use-case is the specification of constant label pairs in Opts or to
- // create a Desc.
- type Labels map[string]string
-
- // ConstrainedLabels represents a label name and its constrain function
- // to normalize label values. This type is commonly used when constructing
- // metric vector Collectors.
- type ConstrainedLabel struct {
- Name string
- Constraint func(string) string
- }
-
- func (cl ConstrainedLabel) Constrain(v string) string {
- if cl.Constraint == nil {
- return v
- }
- return cl.Constraint(v)
- }
-
- // ConstrainableLabels is an interface that allows creating of labels that can
- // be optionally constrained.
- //
- // prometheus.V2().NewCounterVec(CounterVecOpts{
- // CounterOpts: {...}, // Usual CounterOpts fields
- // VariableLabels: []ConstrainedLabels{
- // {Name: "A"},
- // {Name: "B", Constraint: func(v string) string { ... }},
- // },
- // })
- type ConstrainableLabels interface {
- constrainedLabels() ConstrainedLabels
- labelNames() []string
- }
-
- // ConstrainedLabels represents a collection of label name -> constrain function
- // to normalize label values. This type is commonly used when constructing
- // metric vector Collectors.
- type ConstrainedLabels []ConstrainedLabel
-
- func (cls ConstrainedLabels) constrainedLabels() ConstrainedLabels {
- return cls
- }
-
- func (cls ConstrainedLabels) labelNames() []string {
- names := make([]string, len(cls))
- for i, label := range cls {
- names[i] = label.Name
- }
- return names
- }
-
- // UnconstrainedLabels represents collection of label without any constraint on
- // their value. Thus, it is simply a collection of label names.
- //
- // UnconstrainedLabels([]string{ "A", "B" })
- //
- // is equivalent to
- //
- // ConstrainedLabels {
- // { Name: "A" },
- // { Name: "B" },
- // }
- type UnconstrainedLabels []string
-
- func (uls UnconstrainedLabels) constrainedLabels() ConstrainedLabels {
- constrainedLabels := make([]ConstrainedLabel, len(uls))
- for i, l := range uls {
- constrainedLabels[i] = ConstrainedLabel{Name: l}
- }
- return constrainedLabels
- }
-
- func (uls UnconstrainedLabels) labelNames() []string {
- return uls
- }
-
- // reservedLabelPrefix is a prefix which is not legal in user-supplied
- // label names.
- const reservedLabelPrefix = "__"
-
- var errInconsistentCardinality = errors.New("inconsistent label cardinality")
-
- func makeInconsistentCardinalityError(fqName string, labels, labelValues []string) error {
- return fmt.Errorf(
- "%w: %q has %d variable labels named %q but %d values %q were provided",
- errInconsistentCardinality, fqName,
- len(labels), labels,
- len(labelValues), labelValues,
- )
- }
-
- func validateValuesInLabels(labels Labels, expectedNumberOfValues int) error {
- if len(labels) != expectedNumberOfValues {
- return fmt.Errorf(
- "%w: expected %d label values but got %d in %#v",
- errInconsistentCardinality, expectedNumberOfValues,
- len(labels), labels,
- )
- }
-
- for name, val := range labels {
- if !utf8.ValidString(val) {
- return fmt.Errorf("label %s: value %q is not valid UTF-8", name, val)
- }
- }
-
- return nil
- }
-
- func validateLabelValues(vals []string, expectedNumberOfValues int) error {
- if len(vals) != expectedNumberOfValues {
- return fmt.Errorf(
- "%w: expected %d label values but got %d in %#v",
- errInconsistentCardinality, expectedNumberOfValues,
- len(vals), vals,
- )
- }
-
- for _, val := range vals {
- if !utf8.ValidString(val) {
- return fmt.Errorf("label value %q is not valid UTF-8", val)
- }
- }
-
- return nil
- }
-
- func checkLabelName(l string) bool {
- return model.LabelName(l).IsValid() && !strings.HasPrefix(l, reservedLabelPrefix)
- }
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