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Merge pull request #803 from prometheus/beorn7/vec 

Export MetricVec (again)
This commit is contained in:
Björn Rabenstein 2020-10-15 14:41:14 +02:00 committed by GitHub
parent 6007b2b5ca 85aa957f63
commit e6ea98bdda
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 305 additions and 67 deletions
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20
prometheus/counter.go
View File

@ -163,7 +163,7 @@ func (c *counter) updateExemplar(v float64, l Labels) {
// (e.g. number of HTTP requests, partitioned by response code and
// method). Create instances with NewCounterVec.
type CounterVec struct {
*metricVec
*MetricVec
}
// NewCounterVec creates a new CounterVec based on the provided CounterOpts and
@ -176,11 +176,11 @@ func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
opts.ConstLabels,
)
return &CounterVec{
metricVec: newMetricVec(desc, func(lvs ...string) Metric {
MetricVec: NewMetricVec(desc, func(lvs ...string) Metric {
if len(lvs) != len(desc.variableLabels) {
panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels, lvs))
}
result := &counter{desc: desc, labelPairs: makeLabelPairs(desc, lvs), now: time.Now}
result := &counter{desc: desc, labelPairs: MakeLabelPairs(desc, lvs), now: time.Now}
result.init(result) // Init self-collection.
return result
}),
@ -188,7 +188,7 @@ func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
}
// GetMetricWithLabelValues returns the Counter for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of
// values (same order as the variable labels in Desc). If that combination of
// label values is accessed for the first time, a new Counter is created.
//
// It is possible to call this method without using the returned Counter to only
@ -202,7 +202,7 @@ func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
// Counter with the same label values is created later.
//
// An error is returned if the number of label values is not the same as the
// number of VariableLabels in Desc (minus any curried labels).
// number of variable labels in Desc (minus any curried labels).
//
// Note that for more than one label value, this method is prone to mistakes
// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
@ -211,7 +211,7 @@ func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
// with a performance overhead (for creating and processing the Labels map).
// See also the GaugeVec example.
func (v *CounterVec) GetMetricWithLabelValues(lvs ...string) (Counter, error) {
metric, err := v.metricVec.getMetricWithLabelValues(lvs...)
metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...)
if metric != nil {
return metric.(Counter), err
}
@ -219,19 +219,19 @@ func (v *CounterVec) GetMetricWithLabelValues(lvs ...string) (Counter, error) {
}
// GetMetricWith returns the Counter for the given Labels map (the label names
// must match those of the VariableLabels in Desc). If that label map is
// must match those of the variable labels in Desc). If that label map is
// accessed for the first time, a new Counter is created. Implications of
// creating a Counter without using it and keeping the Counter for later use are
// the same as for GetMetricWithLabelValues.
//
// An error is returned if the number and names of the Labels are inconsistent
// with those of the VariableLabels in Desc (minus any curried labels).
// with those of the variable labels in Desc (minus any curried labels).
//
// This method is used for the same purpose as
// GetMetricWithLabelValues(...string). See there for pros and cons of the two
// methods.
func (v *CounterVec) GetMetricWith(labels Labels) (Counter, error) {
metric, err := v.metricVec.getMetricWith(labels)
metric, err := v.MetricVec.GetMetricWith(labels)
if metric != nil {
return metric.(Counter), err
}
@ -275,7 +275,7 @@ func (v *CounterVec) With(labels Labels) Counter {
// registered with a given registry (usually the uncurried version). The Reset
// method deletes all metrics, even if called on a curried vector.
func (v *CounterVec) CurryWith(labels Labels) (*CounterVec, error) {
vec, err := v.curryWith(labels)
vec, err := v.MetricVec.CurryWith(labels)
if vec != nil {
return &CounterVec{vec}, err
}

2
prometheus/desc.go
View File

@ -51,7 +51,7 @@ type Desc struct {
// constLabelPairs contains precalculated DTO label pairs based on
// the constant labels.
constLabelPairs []*dto.LabelPair
// VariableLabels contains names of labels for which the metric
// variableLabels contains names of labels for which the metric
// maintains variable values.
variableLabels []string
// id is a hash of the values of the ConstLabels and fqName. This

163
prometheus/example_metricvec_test.go Normal file
View File

@ -0,0 +1,163 @@
// Copyright 2020 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_test
import (
//lint:ignore SA1019 Need to keep deprecated package for compatibility.
"fmt"
"github.com/golang/protobuf/proto"
dto "github.com/prometheus/client_model/go"
"github.com/prometheus/client_golang/prometheus"
)
// Info implements an info pseudo-metric, which is modeled as a Gauge that
// always has a value of 1. In practice, you would just use a Gauge directly,
// but for this example, we pretend it would be useful to have a “native”
// implementation.
type Info struct {
desc *prometheus.Desc
labelPairs []*dto.LabelPair
}
func (i Info) Desc() *prometheus.Desc {
return i.desc
}
func (i Info) Write(out *dto.Metric) error {
out.Label = i.labelPairs
out.Gauge = &dto.Gauge{Value: proto.Float64(1)}
return nil
}
// InfoVec is the vector version for Info. As an info metric never changes, we
// wouldn't really need to wrap GetMetricWithLabelValues and GetMetricWith
// because Info has no additional methods compared to the vanilla Metric that
// the unwrapped MetricVec methods return. However, to demonstrate all there is
// to do to fully implement a vector for a custom Metric implementation, we do
// it in this example anyway.
type InfoVec struct {
*prometheus.MetricVec
}
func NewInfoVec(name, help string, labelNames []string) *InfoVec {
desc := prometheus.NewDesc(name, help, labelNames, nil)
return &InfoVec{
MetricVec: prometheus.NewMetricVec(desc, func(lvs ...string) prometheus.Metric {
if len(lvs) != len(labelNames) {
panic("inconsistent label cardinality")
}
return Info{desc: desc, labelPairs: prometheus.MakeLabelPairs(desc, lvs)}
}),
}
}
func (v *InfoVec) GetMetricWithLabelValues(lvs ...string) (Info, error) {
metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...)
return metric.(Info), err
}
func (v *InfoVec) GetMetricWith(labels prometheus.Labels) (Info, error) {
metric, err := v.MetricVec.GetMetricWith(labels)
return metric.(Info), err
}
func (v *InfoVec) WithLabelValues(lvs ...string) Info {
i, err := v.GetMetricWithLabelValues(lvs...)
if err != nil {
panic(err)
}
return i
}
func (v *InfoVec) With(labels prometheus.Labels) Info {
i, err := v.GetMetricWith(labels)
if err != nil {
panic(err)
}
return i
}
func (v *InfoVec) CurryWith(labels prometheus.Labels) (*InfoVec, error) {
vec, err := v.MetricVec.CurryWith(labels)
if vec != nil {
return &InfoVec{vec}, err
}
return nil, err
}
func (v *InfoVec) MustCurryWith(labels prometheus.Labels) *InfoVec {
vec, err := v.CurryWith(labels)
if err != nil {
panic(err)
}
return vec
}
func ExampleMetricVec() {
infoVec := NewInfoVec(
"library_version_info",
"Versions of the libraries used in this binary.",
[]string{"library", "version"},
)
infoVec.WithLabelValues("prometheus/client_golang", "1.7.1")
infoVec.WithLabelValues("k8s.io/client-go", "0.18.8")
// Just for demonstration, let's check the state of the InfoVec by
// registering it with a custom registry and then let it collect the
// metrics.
reg := prometheus.NewRegistry()
reg.MustRegister(infoVec)
metricFamilies, err := reg.Gather()
if err != nil || len(metricFamilies) != 1 {
panic("unexpected behavior of custom test registry")
}
fmt.Println(proto.MarshalTextString(metricFamilies[0]))
// Output:
// name: "library_version_info"
// help: "Versions of the libraries used in this binary."
// type: GAUGE
// metric: <
// label: <
// name: "library"
// value: "k8s.io/client-go"
// >
// label: <
// name: "version"
// value: "0.18.8"
// >
// gauge: <
// value: 1
// >
// >
// metric: <
// label: <
// name: "library"
// value: "prometheus/client_golang"
// >
// label: <
// name: "version"
// value: "1.7.1"
// >
// gauge: <
// value: 1
// >
// >
}

20
prometheus/gauge.go
View File

@ -132,7 +132,7 @@ func (g *gauge) Write(out *dto.Metric) error {
// (e.g. number of operations queued, partitioned by user and operation
// type). Create instances with NewGaugeVec.
type GaugeVec struct {
*metricVec
*MetricVec
}
// NewGaugeVec creates a new GaugeVec based on the provided GaugeOpts and
@ -145,11 +145,11 @@ func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
opts.ConstLabels,
)
return &GaugeVec{
metricVec: newMetricVec(desc, func(lvs ...string) Metric {
MetricVec: NewMetricVec(desc, func(lvs ...string) Metric {
if len(lvs) != len(desc.variableLabels) {
panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels, lvs))
}
result := &gauge{desc: desc, labelPairs: makeLabelPairs(desc, lvs)}
result := &gauge{desc: desc, labelPairs: MakeLabelPairs(desc, lvs)}
result.init(result) // Init self-collection.
return result
}),
@ -157,7 +157,7 @@ func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
}
// GetMetricWithLabelValues returns the Gauge for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of
// values (same order as the variable labels in Desc). If that combination of
// label values is accessed for the first time, a new Gauge is created.
//
// It is possible to call this method without using the returned Gauge to only
@ -172,7 +172,7 @@ func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
// example.
//
// An error is returned if the number of label values is not the same as the
// number of VariableLabels in Desc (minus any curried labels).
// number of variable labels in Desc (minus any curried labels).
//
// Note that for more than one label value, this method is prone to mistakes
// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
@ -180,7 +180,7 @@ func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
// latter has a much more readable (albeit more verbose) syntax, but it comes
// with a performance overhead (for creating and processing the Labels map).
func (v *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
metric, err := v.metricVec.getMetricWithLabelValues(lvs...)
metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...)
if metric != nil {
return metric.(Gauge), err
}
@ -188,19 +188,19 @@ func (v *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
}
// GetMetricWith returns the Gauge for the given Labels map (the label names
// must match those of the VariableLabels in Desc). If that label map is
// must match those of the variable labels in Desc). If that label map is
// accessed for the first time, a new Gauge is created. Implications of
// creating a Gauge without using it and keeping the Gauge for later use are
// the same as for GetMetricWithLabelValues.
//
// An error is returned if the number and names of the Labels are inconsistent
// with those of the VariableLabels in Desc (minus any curried labels).
// with those of the variable labels in Desc (minus any curried labels).
//
// This method is used for the same purpose as
// GetMetricWithLabelValues(...string). See there for pros and cons of the two
// methods.
func (v *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
metric, err := v.metricVec.getMetricWith(labels)
metric, err := v.MetricVec.GetMetricWith(labels)
if metric != nil {
return metric.(Gauge), err
}
@ -244,7 +244,7 @@ func (v *GaugeVec) With(labels Labels) Gauge {
// registered with a given registry (usually the uncurried version). The Reset
// method deletes all metrics, even if called on a curried vector.
func (v *GaugeVec) CurryWith(labels Labels) (*GaugeVec, error) {
vec, err := v.curryWith(labels)
vec, err := v.MetricVec.CurryWith(labels)
if vec != nil {
return &GaugeVec{vec}, err
}

22
prometheus/histogram.go
View File

@ -192,7 +192,7 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
h := &histogram{
desc: desc,
upperBounds: opts.Buckets,
labelPairs: makeLabelPairs(desc, labelValues),
labelPairs: MakeLabelPairs(desc, labelValues),
counts: [2]*histogramCounts{{}, {}},
now: time.Now,
}
@ -409,7 +409,7 @@ func (h *histogram) updateExemplar(v float64, bucket int, l Labels) {
// (e.g. HTTP request latencies, partitioned by status code and method). Create
// instances with NewHistogramVec.
type HistogramVec struct {
*metricVec
*MetricVec
}
// NewHistogramVec creates a new HistogramVec based on the provided HistogramOpts and
@ -422,14 +422,14 @@ func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec {
opts.ConstLabels,
)
return &HistogramVec{
metricVec: newMetricVec(desc, func(lvs ...string) Metric {
MetricVec: NewMetricVec(desc, func(lvs ...string) Metric {
return newHistogram(desc, opts, lvs...)
}),
}
}
// GetMetricWithLabelValues returns the Histogram for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of
// values (same order as the variable labels in Desc). If that combination of
// label values is accessed for the first time, a new Histogram is created.
//
// It is possible to call this method without using the returned Histogram to only
@ -444,7 +444,7 @@ func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec {
// example.
//
// An error is returned if the number of label values is not the same as the
// number of VariableLabels in Desc (minus any curried labels).
// number of variable labels in Desc (minus any curried labels).
//
// Note that for more than one label value, this method is prone to mistakes
// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
@ -453,7 +453,7 @@ func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec {
// with a performance overhead (for creating and processing the Labels map).
// See also the GaugeVec example.
func (v *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
metric, err := v.metricVec.getMetricWithLabelValues(lvs...)
metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...)
if metric != nil {
return metric.(Observer), err
}
@ -461,19 +461,19 @@ func (v *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Observer, error)
}
// GetMetricWith returns the Histogram for the given Labels map (the label names
// must match those of the VariableLabels in Desc). If that label map is
// must match those of the variable labels in Desc). If that label map is
// accessed for the first time, a new Histogram is created. Implications of
// creating a Histogram without using it and keeping the Histogram for later use
// are the same as for GetMetricWithLabelValues.
//
// An error is returned if the number and names of the Labels are inconsistent
// with those of the VariableLabels in Desc (minus any curried labels).
// with those of the variable labels in Desc (minus any curried labels).
//
// This method is used for the same purpose as
// GetMetricWithLabelValues(...string). See there for pros and cons of the two
// methods.
func (v *HistogramVec) GetMetricWith(labels Labels) (Observer, error) {
metric, err := v.metricVec.getMetricWith(labels)
metric, err := v.MetricVec.GetMetricWith(labels)
if metric != nil {
return metric.(Observer), err
}
@ -517,7 +517,7 @@ func (v *HistogramVec) With(labels Labels) Observer {
// registered with a given registry (usually the uncurried version). The Reset
// method deletes all metrics, even if called on a curried vector.
func (v *HistogramVec) CurryWith(labels Labels) (ObserverVec, error) {
vec, err := v.curryWith(labels)
vec, err := v.MetricVec.CurryWith(labels)
if vec != nil {
return &HistogramVec{vec}, err
}
@ -602,7 +602,7 @@ func NewConstHistogram(
count: count,
sum: sum,
buckets: buckets,
labelPairs: makeLabelPairs(desc, labelValues),
labelPairs: MakeLabelPairs(desc, labelValues),
}, nil
}

24
prometheus/summary.go
View File

@ -208,7 +208,7 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
// Use the lock-free implementation of a Summary without objectives.
s := &noObjectivesSummary{
desc: desc,
labelPairs: makeLabelPairs(desc, labelValues),
labelPairs: MakeLabelPairs(desc, labelValues),
counts: [2]*summaryCounts{{}, {}},
}
s.init(s) // Init self-collection.
@ -221,7 +221,7 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
objectives: opts.Objectives,
sortedObjectives: make([]float64, 0, len(opts.Objectives)),
labelPairs: makeLabelPairs(desc, labelValues),
labelPairs: MakeLabelPairs(desc, labelValues),
hotBuf: make([]float64, 0, opts.BufCap),
coldBuf: make([]float64, 0, opts.BufCap),
@ -513,7 +513,7 @@ func (s quantSort) Less(i, j int) bool {
// (e.g. HTTP request latencies, partitioned by status code and method). Create
// instances with NewSummaryVec.
type SummaryVec struct {
*metricVec
*MetricVec
}
// NewSummaryVec creates a new SummaryVec based on the provided SummaryOpts and
@ -535,14 +535,14 @@ func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec {
opts.ConstLabels,
)
return &SummaryVec{
metricVec: newMetricVec(desc, func(lvs ...string) Metric {
MetricVec: NewMetricVec(desc, func(lvs ...string) Metric {
return newSummary(desc, opts, lvs...)
}),
}
}
// GetMetricWithLabelValues returns the Summary for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of
// values (same order as the variable labels in Desc). If that combination of
// label values is accessed for the first time, a new Summary is created.
//
// It is possible to call this method without using the returned Summary to only
@ -557,7 +557,7 @@ func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec {
// example.
//
// An error is returned if the number of label values is not the same as the
// number of VariableLabels in Desc (minus any curried labels).
// number of variable labels in Desc (minus any curried labels).
//
// Note that for more than one label value, this method is prone to mistakes
// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
@ -566,7 +566,7 @@ func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec {
// with a performance overhead (for creating and processing the Labels map).
// See also the GaugeVec example.
func (v *SummaryVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
metric, err := v.metricVec.getMetricWithLabelValues(lvs...)
metric, err := v.MetricVec.GetMetricWithLabelValues(lvs...)
if metric != nil {
return metric.(Observer), err
}
@ -574,19 +574,19 @@ func (v *SummaryVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
}
// GetMetricWith returns the Summary for the given Labels map (the label names
// must match those of the VariableLabels in Desc). If that label map is
// must match those of the variable labels in Desc). If that label map is
// accessed for the first time, a new Summary is created. Implications of
// creating a Summary without using it and keeping the Summary for later use are
// the same as for GetMetricWithLabelValues.
//
// An error is returned if the number and names of the Labels are inconsistent
// with those of the VariableLabels in Desc (minus any curried labels).
// with those of the variable labels in Desc (minus any curried labels).
//
// This method is used for the same purpose as
// GetMetricWithLabelValues(...string). See there for pros and cons of the two
// methods.
func (v *SummaryVec) GetMetricWith(labels Labels) (Observer, error) {
metric, err := v.metricVec.getMetricWith(labels)
metric, err := v.MetricVec.GetMetricWith(labels)
if metric != nil {
return metric.(Observer), err
}
@ -630,7 +630,7 @@ func (v *SummaryVec) With(labels Labels) Observer {
// registered with a given registry (usually the uncurried version). The Reset
// method deletes all metrics, even if called on a curried vector.
func (v *SummaryVec) CurryWith(labels Labels) (ObserverVec, error) {
vec, err := v.curryWith(labels)
vec, err := v.MetricVec.CurryWith(labels)
if vec != nil {
return &SummaryVec{vec}, err
}
@ -716,7 +716,7 @@ func NewConstSummary(
count: count,
sum: sum,
quantiles: quantiles,
labelPairs: makeLabelPairs(desc, labelValues),
labelPairs: MakeLabelPairs(desc, labelValues),
}, nil
}

13
prometheus/value.go
View File

@ -63,7 +63,7 @@ func newValueFunc(desc *Desc, valueType ValueType, function func() float64) *val
desc: desc,
valType: valueType,
function: function,
labelPairs: makeLabelPairs(desc, nil),
labelPairs: MakeLabelPairs(desc, nil),
}
result.init(result)
return result
@ -95,7 +95,7 @@ func NewConstMetric(desc *Desc, valueType ValueType, value float64, labelValues
desc: desc,
valType: valueType,
val: value,
labelPairs: makeLabelPairs(desc, labelValues),
labelPairs: MakeLabelPairs(desc, labelValues),
}, nil
}
@ -145,7 +145,14 @@ func populateMetric(
return nil
}
func makeLabelPairs(desc *Desc, labelValues []string) []*dto.LabelPair {
// MakeLabelPairs is a helper function to create protobuf LabelPairs from the
// variable and constant labels in the provided Desc. The values for the
// variable labels are defined by the labelValues slice, which must be in the
// same order as the corresponding variable labels in the Desc.
//
// This function is only needed for custom Metric implementations. See MetricVec
// example.
func MakeLabelPairs(desc *Desc, labelValues []string) []*dto.LabelPair {
totalLen := len(desc.variableLabels) + len(desc.constLabelPairs)
if totalLen == 0 {
// Super fast path.

108
prometheus/vec.go
View File

@ -20,12 +20,20 @@ import (
"github.com/prometheus/common/model"
)
// metricVec is a Collector to bundle metrics of the same name that differ in
// their label values. metricVec is not used directly (and therefore
// unexported). It is used as a building block for implementations of vectors of
// a given metric type, like GaugeVec, CounterVec, SummaryVec, and HistogramVec.
// It also handles label currying.
type metricVec struct {
// MetricVec is a Collector to bundle metrics of the same name that differ in
// their label values. MetricVec is not used directly but as a building block
// for implementations of vectors of a given metric type, like GaugeVec,
// CounterVec, SummaryVec, and HistogramVec. It is exported so that it can be
// used for custom Metric implementations.
//
// To create a FooVec for custom Metric Foo, embed a pointer to MetricVec in
// FooVec and initialize it with NewMetricVec. Implement wrappers for
// GetMetricWithLabelValues and GetMetricWith that return (Foo, error) rather
// than (Metric, error). Similarly, create a wrapper for CurryWith that returns
// (*FooVec, error) rather than (*MetricVec, error). It is recommended to also
// add the convenience methods WithLabelValues, With, and MustCurryWith, which
// panic instead of returning errors. See also the MetricVec example.
type MetricVec struct {
*metricMap
curry []curriedLabelValue
@ -35,9 +43,9 @@ type metricVec struct {
hashAddByte func(h uint64, b byte) uint64
}
// newMetricVec returns an initialized metricVec.
func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *metricVec {
return &metricVec{
// NewMetricVec returns an initialized metricVec.
func NewMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *MetricVec {
return &MetricVec{
metricMap: &metricMap{
metrics: map[uint64][]metricWithLabelValues{},
desc: desc,
@ -63,7 +71,7 @@ func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *metricVec {
// latter has a much more readable (albeit more verbose) syntax, but it comes
// with a performance overhead (for creating and processing the Labels map).
// See also the CounterVec example.
func (m *metricVec) DeleteLabelValues(lvs ...string) bool {
func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
h, err := m.hashLabelValues(lvs)
if err != nil {
return false
@ -82,7 +90,7 @@ func (m *metricVec) DeleteLabelValues(lvs ...string) bool {
//
// This method is used for the same purpose as DeleteLabelValues(...string). See
// there for pros and cons of the two methods.
func (m *metricVec) Delete(labels Labels) bool {
func (m *MetricVec) Delete(labels Labels) bool {
h, err := m.hashLabels(labels)
if err != nil {
return false
@ -95,15 +103,32 @@ func (m *metricVec) Delete(labels Labels) bool {
// show up in GoDoc.
// Describe implements Collector.
func (m *metricVec) Describe(ch chan<- *Desc) { m.metricMap.Describe(ch) }
func (m *MetricVec) Describe(ch chan<- *Desc) { m.metricMap.Describe(ch) }
// Collect implements Collector.
func (m *metricVec) Collect(ch chan<- Metric) { m.metricMap.Collect(ch) }
func (m *MetricVec) Collect(ch chan<- Metric) { m.metricMap.Collect(ch) }
// Reset deletes all metrics in this vector.
func (m *metricVec) Reset() { m.metricMap.Reset() }
func (m *MetricVec) Reset() { m.metricMap.Reset() }
func (m *metricVec) curryWith(labels Labels) (*metricVec, error) {
// CurryWith returns a vector curried with the provided labels, i.e. the
// returned vector has those labels pre-set for all labeled operations performed
// on it. The cardinality of the curried vector is reduced accordingly. The
// order of the remaining labels stays the same (just with the curried labels
// taken out of the sequence – which is relevant for the
// (GetMetric)WithLabelValues methods). It is possible to curry a curried
// vector, but only with labels not yet used for currying before.
//
// The metrics contained in the MetricVec are shared between the curried and
// uncurried vectors. They are just accessed differently. Curried and uncurried
// vectors behave identically in terms of collection. Only one must be
// registered with a given registry (usually the uncurried version). The Reset
// method deletes all metrics, even if called on a curried vector.
//
// Note that CurryWith is usually not called directly but through a wrapper
// around MetricVec, implementing a vector for a specific Metric
// implementation, for example GaugeVec.
func (m *MetricVec) CurryWith(labels Labels) (*MetricVec, error) {
var (
newCurry []curriedLabelValue
oldCurry = m.curry
@ -128,7 +153,7 @@ func (m *metricVec) curryWith(labels Labels) (*metricVec, error) {
return nil, fmt.Errorf("%d unknown label(s) found during currying", l)
}
return &metricVec{
return &MetricVec{
metricMap: m.metricMap,
curry: newCurry,
hashAdd: m.hashAdd,
@ -136,7 +161,34 @@ func (m *metricVec) curryWith(labels Labels) (*metricVec, error) {
}, nil
}
func (m *metricVec) getMetricWithLabelValues(lvs ...string) (Metric, error) {
// GetMetricWithLabelValues returns the Metric for the given slice of label
// values (same order as the variable labels in Desc). If that combination of
// label values is accessed for the first time, a new Metric is created (by
// calling the newMetric function provided during construction of the
// MetricVec).
//
// It is possible to call this method without using the returned Metry to only
// create the new Metric but leave it in its intitial state.
//
// Keeping the Metric for later use is possible (and should be considered if
// performance is critical), but keep in mind that Reset, DeleteLabelValues and
// Delete can be used to delete the Metric from the MetricVec. In that case, the
// Metric will still exist, but it will not be exported anymore, even if a
// Metric with the same label values is created later.
//
// An error is returned if the number of label values is not the same as the
// number of variable labels in Desc (minus any curried labels).
//
// Note that for more than one label value, this method is prone to mistakes
// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
// an alternative to avoid that type of mistake. For higher label numbers, the
// latter has a much more readable (albeit more verbose) syntax, but it comes
// with a performance overhead (for creating and processing the Labels map).
//
// Note that GetMetricWithLabelValues is usually not called directly but through
// a wrapper around MetricVec, implementing a vector for a specific Metric
// implementation, for example GaugeVec.
func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
h, err := m.hashLabelValues(lvs)
if err != nil {
return nil, err
@ -145,7 +197,23 @@ func (m *metricVec) getMetricWithLabelValues(lvs ...string) (Metric, error) {
return m.metricMap.getOrCreateMetricWithLabelValues(h, lvs, m.curry), nil
}
func (m *metricVec) getMetricWith(labels Labels) (Metric, error) {
// GetMetricWith returns the Metric for the given Labels map (the label names
// must match those of the variable labels in Desc). If that label map is
// accessed for the first time, a new Metric is created. Implications of
// creating a Metric without using it and keeping the Metric for later use
// are the same as for GetMetricWithLabelValues.
//
// An error is returned if the number and names of the Labels are inconsistent
// with those of the variable labels in Desc (minus any curried labels).
//
// This method is used for the same purpose as
// GetMetricWithLabelValues(...string). See there for pros and cons of the two
// methods.
//
// Note that GetMetricWith is usually not called directly but through a wrapper
// around MetricVec, implementing a vector for a specific Metric implementation,
// for example GaugeVec.
func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) {
h, err := m.hashLabels(labels)
if err != nil {
return nil, err
@ -154,7 +222,7 @@ func (m *metricVec) getMetricWith(labels Labels) (Metric, error) {
return m.metricMap.getOrCreateMetricWithLabels(h, labels, m.curry), nil
}
func (m *metricVec) hashLabelValues(vals []string) (uint64, error) {
func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) {
if err := validateLabelValues(vals, len(m.desc.variableLabels)-len(m.curry)); err != nil {
return 0, err
}
@ -177,7 +245,7 @@ func (m *metricVec) hashLabelValues(vals []string) (uint64, error) {
return h, nil
}
func (m *metricVec) hashLabels(labels Labels) (uint64, error) {
func (m *MetricVec) hashLabels(labels Labels) (uint64, error) {
if err := validateValuesInLabels(labels, len(m.desc.variableLabels)-len(m.curry)); err != nil {
return 0, err
}