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Finish making Gauge and TimingHistogram implement the same interface

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This commit is contained in:
Mike Spreitzer 2022-05-11 09:04:17 -04:00
parent 4df968ae1c
commit c87cd36d3e
6 changed files with 128 additions and 73 deletions
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17
staging/src/k8s.io/component-base/metrics/counter.go
View File

@ -18,6 +18,7 @@ package metrics
import (
"context"
"github.com/blang/semver/v4"
"github.com/prometheus/client_golang/prometheus"
dto "github.com/prometheus/client_model/go"
@ -106,9 +107,14 @@ type CounterVec struct {
originalLabels []string
}
// NewCounterVec returns an object which satisfies the kubeCollector and CounterVecMetric interfaces.
var _ kubeCollector = &CounterVec{}
// TODO: make this true: var _ CounterVecMetric = &CounterVec{}
// NewCounterVec returns an object which satisfies the kubeCollector and (almost) CounterVecMetric interfaces.
// However, the object returned will not measure anything unless the collector is first
// registered, since the metric is lazily instantiated.
// registered, since the metric is lazily instantiated, and only members extracted after
// registration will actually measure anything.
func NewCounterVec(opts *CounterOpts, labels []string) *CounterVec {
opts.StabilityLevel.setDefaults()
@ -149,13 +155,16 @@ func (v *CounterVec) initializeDeprecatedMetric() {
v.initializeMetric()
}
// Default Prometheus behavior actually results in the creation of a new metric
// if a metric with the unique label values is not found in the underlying stored metricMap.
// Default Prometheus Vec behavior is that member extraction results in creation of a new element
// if one with the unique label values is not found in the underlying stored metricMap.
// This means that if this function is called but the underlying metric is not registered
// (which means it will never be exposed externally nor consumed), the metric will exist in memory
// for perpetuity (i.e. throughout application lifecycle).
//
// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/counter.go#L179-L197
//
// In contrast, the Vec behavior in this package is that member extraction before registration
// returns a permanent noop object.
// WithLabelValues returns the Counter for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of

69
staging/src/k8s.io/component-base/metrics/gauge.go
View File

@ -18,6 +18,7 @@ package metrics
import (
"context"
"github.com/blang/semver/v4"
"github.com/prometheus/client_golang/prometheus"
@ -33,7 +34,11 @@ type Gauge struct {
selfCollector
}
// NewGauge returns an object which satisfies the kubeCollector and KubeGauge interfaces.
var _ GaugeMetric = &Gauge{}
var _ Registerable = &Gauge{}
var _ kubeCollector = &Gauge{}
// NewGauge returns an object which satisfies the kubeCollector, Registerable, and Gauge interfaces.
// However, the object returned will not measure anything unless the collector is first
// registered, since the metric is lazily instantiated.
func NewGauge(opts *GaugeOpts) *Gauge {
@ -88,9 +93,14 @@ type GaugeVec struct {
originalLabels []string
}
// NewGaugeVec returns an object which satisfies the kubeCollector and KubeGaugeVec interfaces.
var _ GaugeVecMetric = &GaugeVec{}
var _ Registerable = &GaugeVec{}
var _ kubeCollector = &GaugeVec{}
// NewGaugeVec returns an object which satisfies the kubeCollector, Registerable, and GaugeVecMetric interfaces.
// However, the object returned will not measure anything unless the collector is first
// registered, since the metric is lazily instantiated.
// registered, since the metric is lazily instantiated, and only members extracted after
// registration will actually measure anything.
func NewGaugeVec(opts *GaugeOpts, labels []string) *GaugeVec {
opts.StabilityLevel.setDefaults()
@ -130,26 +140,55 @@ func (v *GaugeVec) initializeDeprecatedMetric() {
v.initializeMetric()
}
// Default Prometheus behavior actually results in the creation of a new metric
// if a metric with the unique label values is not found in the underlying stored metricMap.
func (v *GaugeVec) WithLabelValuesChecked(lvs ...string) (GaugeMetric, error) {
if v.IsHidden() {
return noop, nil
}
if !v.IsCreated() {
return noop, errNotRegistered // return no-op gauge
}
if v.LabelValueAllowLists != nil {
v.LabelValueAllowLists.ConstrainToAllowedList(v.originalLabels, lvs)
}
elt, err := v.GaugeVec.GetMetricWithLabelValues(lvs...)
return elt, err
}
// Default Prometheus Vec behavior is that member extraction results in creation of a new element
// if one with the unique label values is not found in the underlying stored metricMap.
// This means that if this function is called but the underlying metric is not registered
// (which means it will never be exposed externally nor consumed), the metric will exist in memory
// for perpetuity (i.e. throughout application lifecycle).
//
// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/gauge.go#L190-L208
//
// In contrast, the Vec behavior in this package is that member extraction before registration
// returns a permanent noop object.
// WithLabelValues returns the GaugeMetric for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of
// label values is accessed for the first time, a new GaugeMetric is created IFF the gaugeVec
// has been registered to a metrics registry.
func (v *GaugeVec) WithLabelValues(lvs ...string) GaugeMetric {
ans, err := v.WithLabelValuesChecked(lvs...)
if err == nil || ErrIsNotRegistered(err) {
return ans
}
panic(err)
}
func (v *GaugeVec) WithChecked(labels map[string]string) (GaugeMetric, error) {
if v.IsHidden() {
return noop, nil
}
if !v.IsCreated() {
return noop // return no-op gauge
return noop, errNotRegistered // return no-op gauge
}
if v.LabelValueAllowLists != nil {
v.LabelValueAllowLists.ConstrainToAllowedList(v.originalLabels, lvs)
v.LabelValueAllowLists.ConstrainLabelMap(labels)
}
return v.GaugeVec.WithLabelValues(lvs...)
elt, err := v.GaugeVec.GetMetricWith(labels)
return elt, err
}
// With returns the GaugeMetric for the given Labels map (the label names
@ -157,13 +196,11 @@ func (v *GaugeVec) WithLabelValues(lvs ...string) GaugeMetric {
// accessed for the first time, a new GaugeMetric is created IFF the gaugeVec has
// been registered to a metrics registry.
func (v *GaugeVec) With(labels map[string]string) GaugeMetric {
if !v.IsCreated() {
return noop // return no-op gauge
ans, err := v.WithChecked(labels)
if err == nil || ErrIsNotRegistered(err) {
return ans
}
if v.LabelValueAllowLists != nil {
v.LabelValueAllowLists.ConstrainLabelMap(labels)
}
return v.GaugeVec.With(labels)
panic(err)
}
// Delete deletes the metric where the variable labels are the same as those
@ -219,6 +256,10 @@ func (v *GaugeVec) WithContext(ctx context.Context) *GaugeVecWithContext {
}
}
func (v *GaugeVec) InterfaceWithContext(ctx context.Context) GaugeVecMetric {
return v.WithContext(ctx)
}
// GaugeVecWithContext is the wrapper of GaugeVec with context.
type GaugeVecWithContext struct {
*GaugeVec

12
staging/src/k8s.io/component-base/metrics/histogram.go
View File

@ -101,7 +101,10 @@ type HistogramVec struct {
// NewHistogramVec returns an object which satisfies kubeCollector and wraps the
// prometheus.HistogramVec object. However, the object returned will not measure
// anything unless the collector is first registered, since the metric is lazily instantiated.
// anything unless the collector is first registered, since the metric is lazily instantiated,
// and only members extracted after
// registration will actually measure anything.
func NewHistogramVec(opts *HistogramOpts, labels []string) *HistogramVec {
opts.StabilityLevel.setDefaults()
@ -137,13 +140,16 @@ func (v *HistogramVec) initializeDeprecatedMetric() {
v.initializeMetric()
}
// Default Prometheus behavior actually results in the creation of a new metric
// if a metric with the unique label values is not found in the underlying stored metricMap.
// Default Prometheus Vec behavior is that member extraction results in creation of a new element
// if one with the unique label values is not found in the underlying stored metricMap.
// This means that if this function is called but the underlying metric is not registered
// (which means it will never be exposed externally nor consumed), the metric will exist in memory
// for perpetuity (i.e. throughout application lifecycle).
//
// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/histogram.go#L460-L470
//
// In contrast, the Vec behavior in this package is that member extraction before registration
// returns a permanent noop object.
// WithLabelValues returns the ObserverMetric for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of

14
staging/src/k8s.io/component-base/metrics/summary.go
View File

@ -18,6 +18,7 @@ package metrics
import (
"context"
"github.com/blang/semver/v4"
"github.com/prometheus/client_golang/prometheus"
)
@ -93,7 +94,9 @@ type SummaryVec struct {
// NewSummaryVec returns an object which satisfies kubeCollector and wraps the
// prometheus.SummaryVec object. However, the object returned will not measure
// anything unless the collector is first registered, since the metric is lazily instantiated.
// anything unless the collector is first registered, since the metric is lazily instantiated,
// and only members extracted after
// registration will actually measure anything.
//
// DEPRECATED: as per the metrics overhaul KEP
func NewSummaryVec(opts *SummaryOpts, labels []string) *SummaryVec {
@ -130,13 +133,16 @@ func (v *SummaryVec) initializeDeprecatedMetric() {
v.initializeMetric()
}
// Default Prometheus behavior actually results in the creation of a new metric
// if a metric with the unique label values is not found in the underlying stored metricMap.
// Default Prometheus Vec behavior is that member extraction results in creation of a new element
// if one with the unique label values is not found in the underlying stored metricMap.
// This means that if this function is called but the underlying metric is not registered
// (which means it will never be exposed externally nor consumed), the metric will exist in memory
// for perpetuity (i.e. throughout application lifecycle).
//
// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/summary.go#L485-L495
// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/histogram.go#L460-L470
//
// In contrast, the Vec behavior in this package is that member extraction before registration
// returns a permanent noop object.
// WithLabelValues returns the ObserverMetric for the given slice of label
// values (same order as the VariableLabels in Desc). If that combination of

50
staging/src/k8s.io/component-base/metrics/timing_histogram.go
View File

@ -34,6 +34,10 @@ type TimingHistogram struct {
selfCollector
}
var _ GaugeMetric = &TimingHistogram{}
var _ Registerable = &TimingHistogram{}
var _ kubeCollector = &TimingHistogram{}
// NewTimingHistogram returns an object which is TimingHistogram-like. However, nothing
// will be measured until the histogram is registered somewhere.
func NewTimingHistogram(opts *TimingHistogramOpts) *TimingHistogram {
@ -89,9 +93,9 @@ func (h *TimingHistogram) WithContext(ctx context.Context) GaugeMetric {
return h.GaugeMetric
}
// timingHistogramVec is the internal representation of our wrapping struct around prometheus
// TimingHistogramVec is the internal representation of our wrapping struct around prometheus
// TimingHistogramVecs.
type timingHistogramVec struct {
type TimingHistogramVec struct {
*promext.TimingHistogramVec
*TimingHistogramOpts
nowFunc func() time.Time
@ -99,15 +103,19 @@ type timingHistogramVec struct {
originalLabels []string
}
// NewTimingHistogramVec returns an object which satisfies kubeCollector and
// wraps the promext.timingHistogramVec object. Note well the way that
var _ GaugeVecMetric = &TimingHistogramVec{}
var _ Registerable = &TimingHistogramVec{}
var _ kubeCollector = &TimingHistogramVec{}
// NewTimingHistogramVec returns an object which satisfies the kubeCollector, Registerable, and GaugeVecMetric interfaces
// and wraps an underlying promext.TimingHistogramVec object. Note well the way that
// behavior depends on registration and whether this is hidden.
func NewTimingHistogramVec(opts *TimingHistogramOpts, labels []string) PreContextAndRegisterableGaugeMetricVec {
func NewTimingHistogramVec(opts *TimingHistogramOpts, labels []string) *TimingHistogramVec {
return NewTestableTimingHistogramVec(time.Now, opts, labels)
}
// NewTestableTimingHistogramVec adds injection of the clock.
func NewTestableTimingHistogramVec(nowFunc func() time.Time, opts *TimingHistogramOpts, labels []string) PreContextAndRegisterableGaugeMetricVec {
func NewTestableTimingHistogramVec(nowFunc func() time.Time, opts *TimingHistogramOpts, labels []string) *TimingHistogramVec {
opts.StabilityLevel.setDefaults()
fqName := BuildFQName(opts.Namespace, opts.Subsystem, opts.Name)
@ -117,7 +125,7 @@ func NewTestableTimingHistogramVec(nowFunc func() time.Time, opts *TimingHistogr
}
allowListLock.RUnlock()
v := &timingHistogramVec{
v := &TimingHistogramVec{
TimingHistogramVec: noopTimingHistogramVec,
TimingHistogramOpts: opts,
nowFunc: nowFunc,
@ -129,16 +137,16 @@ func NewTestableTimingHistogramVec(nowFunc func() time.Time, opts *TimingHistogr
}
// DeprecatedVersion returns a pointer to the Version or nil
func (v *timingHistogramVec) DeprecatedVersion() *semver.Version {
func (v *TimingHistogramVec) DeprecatedVersion() *semver.Version {
return parseSemver(v.TimingHistogramOpts.DeprecatedVersion)
}
func (v *timingHistogramVec) initializeMetric() {
func (v *TimingHistogramVec) initializeMetric() {
v.TimingHistogramOpts.annotateStabilityLevel()
v.TimingHistogramVec = promext.NewTestableTimingHistogramVec(v.nowFunc, v.TimingHistogramOpts.toPromHistogramOpts(), v.originalLabels...)
}
func (v *timingHistogramVec) initializeDeprecatedMetric() {
func (v *TimingHistogramVec) initializeDeprecatedMetric() {
v.TimingHistogramOpts.markDeprecated()
v.initializeMetric()
}
@ -152,7 +160,7 @@ func (v *timingHistogramVec) initializeDeprecatedMetric() {
// return a noop gauge and an error about the labels.
// If none of the above apply, this method will return
// the appropriate vector member and a nil error.
func (v *timingHistogramVec) WithLabelValuesChecked(lvs ...string) (GaugeMetric, error) {
func (v *TimingHistogramVec) WithLabelValuesChecked(lvs ...string) (GaugeMetric, error) {
if v.IsHidden() {
return noop, nil
}
@ -171,7 +179,7 @@ func (v *timingHistogramVec) WithLabelValuesChecked(lvs ...string) (GaugeMetric,
// An error that passes ErrIsNotRegistered is ignored
// and the noop gauge is returned;
// all other errors cause a panic.
func (v *timingHistogramVec) WithLabelValues(lvs ...string) GaugeMetric {
func (v *TimingHistogramVec) WithLabelValues(lvs ...string) GaugeMetric {
ans, err := v.WithLabelValuesChecked(lvs...)
if err == nil || ErrIsNotRegistered(err) {
return ans
@ -188,7 +196,7 @@ func (v *timingHistogramVec) WithLabelValues(lvs ...string) GaugeMetric {
// return a noop gauge and an error about the labels.
// If none of the above apply, this method will return
// the appropriate vector member and a nil error.
func (v *timingHistogramVec) WithChecked(labels map[string]string) (GaugeMetric, error) {
func (v *TimingHistogramVec) WithChecked(labels map[string]string) (GaugeMetric, error) {
if v.IsHidden() {
return noop, nil
}
@ -206,7 +214,7 @@ func (v *timingHistogramVec) WithChecked(labels map[string]string) (GaugeMetric,
// An error that passes ErrIsNotRegistered is ignored
// and the noop gauge is returned;
// all other errors cause a panic.
func (v *timingHistogramVec) With(labels map[string]string) GaugeMetric {
func (v *TimingHistogramVec) With(labels map[string]string) GaugeMetric {
ans, err := v.WithChecked(labels)
if err == nil || ErrIsNotRegistered(err) {
return ans
@ -221,7 +229,7 @@ func (v *timingHistogramVec) With(labels map[string]string) GaugeMetric {
// with those of the VariableLabels in Desc. However, such inconsistent Labels
// can never match an actual metric, so the method will always return false in
// that case.
func (v *timingHistogramVec) Delete(labels map[string]string) bool {
func (v *TimingHistogramVec) Delete(labels map[string]string) bool {
if !v.IsCreated() {
return false // since we haven't created the metric, we haven't deleted a metric with the passed in values
}
@ -229,7 +237,7 @@ func (v *timingHistogramVec) Delete(labels map[string]string) bool {
}
// Reset deletes all metrics in this vector.
func (v *timingHistogramVec) Reset() {
func (v *TimingHistogramVec) Reset() {
if !v.IsCreated() {
return
}
@ -237,17 +245,17 @@ func (v *timingHistogramVec) Reset() {
v.TimingHistogramVec.Reset()
}
// WithContext returns wrapped timingHistogramVec with context
func (v *timingHistogramVec) WithContext(ctx context.Context) GaugeMetricVec {
// WithContext returns wrapped TimingHistogramVec with context
func (v *TimingHistogramVec) InterfaceWithContext(ctx context.Context) GaugeVecMetric {
return &TimingHistogramVecWithContext{
ctx: ctx,
timingHistogramVec: v,
TimingHistogramVec: v,
}
}
// TimingHistogramVecWithContext is the wrapper of timingHistogramVec with context.
// TimingHistogramVecWithContext is the wrapper of TimingHistogramVec with context.
// Currently the context is ignored.
type TimingHistogramVecWithContext struct {
*timingHistogramVec
*TimingHistogramVec
ctx context.Context
}

39
staging/src/k8s.io/component-base/metrics/wrappers.go
View File

@ -17,7 +17,6 @@ limitations under the License.
package metrics
import (
"context"
"errors"
"github.com/prometheus/client_golang/prometheus"
@ -68,12 +67,18 @@ type GaugeMetric interface {
SetToCurrentTime()
}
// GaugeMetricVec is a collection of Gauges that differ only in label values.
// This is really just one Metric.
// It might be better called GaugeVecMetric, but that pattern of name is already
// taken by the other pattern --- which is treacherous. The treachery is that
// WithLabelValues can return an object that is permanently broken (i.e., a noop).
type GaugeMetricVec interface {
// GaugeVecMetric is a collection of Gauges that differ only in label values.
type GaugeVecMetric interface {
// Default Prometheus Vec behavior is that member extraction results in creation of a new element
// if one with the unique label values is not found in the underlying stored metricMap.
// This means that if this function is called but the underlying metric is not registered
// (which means it will never be exposed externally nor consumed), the metric would exist in memory
// for perpetuity (i.e. throughout application lifecycle).
//
// For reference: https://github.com/prometheus/client_golang/blob/v0.9.2/prometheus/gauge.go#L190-L208
//
// In contrast, the Vec behavior in this package is that member extraction before registration
// returns a permanent noop object.
// WithLabelValuesChecked, if called on a hidden vector,
// will return a noop gauge and a nil error.
@ -120,26 +125,6 @@ type GaugeMetricVec interface {
Reset()
}
// PreContextGaugeMetricVec is something that can construct a GaugeMetricVec
// that uses a given Context.
type PreContextGaugeMetricVec interface {
// WithContext creates a GaugeMetricVec that uses the given Context
WithContext(ctx context.Context) GaugeMetricVec
}
// RegisterableGaugeMetricVec is the intersection of Registerable and GaugeMetricVec
type RegisterableGaugeMetricVec interface {
Registerable
GaugeMetricVec
}
// PreContextAndRegisterableGaugeMetricVec is the intersection of
// PreContextGaugeMetricVec and RegisterableGaugeMetricVec
type PreContextAndRegisterableGaugeMetricVec interface {
PreContextGaugeMetricVec
RegisterableGaugeMetricVec
}
// ObserverMetric captures individual observations.
type ObserverMetric interface {
Observe(float64)