Add wrapper for TimingHistogram

Do not bother wrapping WeightedHistogram because it is not used
in k/k.

hack/verify-prometheus-imports.sh

@@ -66,6 +66,7 @@ allowed_prometheus_importers=(
   ./staging/src/k8s.io/component-base/metrics/testutil/metrics_test.go
   ./staging/src/k8s.io/component-base/metrics/testutil/promlint.go
   ./staging/src/k8s.io/component-base/metrics/testutil/testutil.go
+  ./staging/src/k8s.io/component-base/metrics/timing_histogram_test.go
   ./staging/src/k8s.io/component-base/metrics/value.go
   ./staging/src/k8s.io/component-base/metrics/wrappers.go
   ./test/e2e/apimachinery/flowcontrol.go

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

@@ -18,6 +18,7 @@ package metrics
 
 import (
 	"context"
+
 	"github.com/blang/semver/v4"
 	"github.com/prometheus/client_golang/prometheus"
 )

staging/src/k8s.io/component-base/metrics/histogram_test.go

@@ -87,6 +87,19 @@ func TestHistogram(t *testing.T) {
 			})
 			c := NewHistogram(test.HistogramOpts)
 			registry.MustRegister(c)
+			cm := c.ObserverMetric.(prometheus.Metric)
+
+			metricChan := make(chan prometheus.Metric, 2)
+			c.Collect(metricChan)
+			close(metricChan)
+			m1 := <-metricChan
+			if m1 != cm {
+				t.Error("Unexpected metric", m1, cm)
+			}
+			m2, ok := <-metricChan
+			if ok {
+				t.Error("Unexpected second metric", m2)
+			}
 
 			ms, err := registry.Gather()
 			assert.Equalf(t, test.expectedMetricCount, len(ms), "Got %v metrics, Want: %v metrics", len(ms), test.expectedMetricCount)
@@ -179,7 +192,24 @@ func TestHistogramVec(t *testing.T) {
 			})
 			c := NewHistogramVec(test.HistogramOpts, test.labels)
 			registry.MustRegister(c)
-			c.WithLabelValues("1", "2").Observe(1.0)
+			ov12 := c.WithLabelValues("1", "2")
+			cm1 := ov12.(prometheus.Metric)
+			ov12.Observe(1.0)
+
+			if test.expectedMetricCount > 0 {
+				metricChan := make(chan prometheus.Metric, 2)
+				c.Collect(metricChan)
+				close(metricChan)
+				m1 := <-metricChan
+				if m1 != cm1 {
+					t.Error("Unexpected metric", m1, cm1)
+				}
+				m2, ok := <-metricChan
+				if ok {
+					t.Error("Unexpected second metric", m2)
+				}
+			}
+
 			ms, err := registry.Gather()
 			assert.Equalf(t, test.expectedMetricCount, len(ms), "Got %v metrics, Want: %v metrics", len(ms), test.expectedMetricCount)
 			assert.Nil(t, err, "Gather failed %v", err)
@@ -218,12 +248,12 @@ func TestHistogramWithLabelValueAllowList(t *testing.T) {
 	var tests = []struct {
 		desc               string
 		labelValues        [][]string
-		expectMetricValues map[string]int
+		expectMetricValues map[string]uint64
 	}{
 		{
 			desc:        "Test no unexpected input",
 			labelValues: [][]string{{"allowed", "b1"}, {"allowed", "b2"}},
-			expectMetricValues: map[string]int{
+			expectMetricValues: map[string]uint64{
 				"allowed b1": 1.0,
 				"allowed b2": 1.0,
 			},
@@ -231,7 +261,7 @@ func TestHistogramWithLabelValueAllowList(t *testing.T) {
 		{
 			desc:        "Test unexpected input",
 			labelValues: [][]string{{"allowed", "b1"}, {"not_allowed", "b1"}},
-			expectMetricValues: map[string]int{
+			expectMetricValues: map[string]uint64{
 				"allowed b1":    1.0,
 				"unexpected b1": 1.0,
 			},
@@ -274,7 +304,7 @@ func TestHistogramWithLabelValueAllowList(t *testing.T) {
 					labelValuePair := aValue + " " + bValue
 					expectedValue, ok := test.expectMetricValues[labelValuePair]
 					assert.True(t, ok, "Got unexpected label values, lable_a is %v, label_b is %v", aValue, bValue)
-					actualValue := int(m.GetHistogram().GetSampleCount())
+					actualValue := m.GetHistogram().GetSampleCount()
 					assert.Equalf(t, expectedValue, actualValue, "Got %v, wanted %v as the count while setting label_a to %v and label b to %v", actualValue, expectedValue, aValue, bValue)
 				}
 			}

staging/src/k8s.io/component-base/metrics/metric.go

@@ -22,6 +22,7 @@ import (
 	"github.com/blang/semver/v4"
 	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
+	promext "k8s.io/component-base/metrics/prometheusextension"
 
 	"k8s.io/klog/v2"
 )
@@ -203,6 +204,7 @@ func (c *selfCollector) Collect(ch chan<- prometheus.Metric) {
 // no-op vecs for convenience
 var noopCounterVec = &prometheus.CounterVec{}
 var noopHistogramVec = &prometheus.HistogramVec{}
+var noopTimingHistogramVec = &promext.TimingHistogramVec{}
 var noopGaugeVec = &prometheus.GaugeVec{}
 var noopObserverVec = &noopObserverVector{}
 
@@ -211,17 +213,18 @@ var noop = &noopMetric{}
 
 type noopMetric struct{}
 
-func (noopMetric) Inc()                             {}
-func (noopMetric) Add(float64)                      {}
-func (noopMetric) Dec()                             {}
-func (noopMetric) Set(float64)                      {}
-func (noopMetric) Sub(float64)                      {}
-func (noopMetric) Observe(float64)                  {}
-func (noopMetric) SetToCurrentTime()                {}
-func (noopMetric) Desc() *prometheus.Desc           { return nil }
-func (noopMetric) Write(*dto.Metric) error          { return nil }
-func (noopMetric) Describe(chan<- *prometheus.Desc) {}
-func (noopMetric) Collect(chan<- prometheus.Metric) {}
+func (noopMetric) Inc()                              {}
+func (noopMetric) Add(float64)                       {}
+func (noopMetric) Dec()                              {}
+func (noopMetric) Set(float64)                       {}
+func (noopMetric) Sub(float64)                       {}
+func (noopMetric) Observe(float64)                   {}
+func (noopMetric) ObserveWithWeight(float64, uint64) {}
+func (noopMetric) SetToCurrentTime()                 {}
+func (noopMetric) Desc() *prometheus.Desc            { return nil }
+func (noopMetric) Write(*dto.Metric) error           { return nil }
+func (noopMetric) Describe(chan<- *prometheus.Desc)  {}
+func (noopMetric) Collect(chan<- prometheus.Metric)  {}
 
 type noopObserverVector struct{}
 

staging/src/k8s.io/component-base/metrics/opts.go

@@ -24,6 +24,7 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus"
 	"k8s.io/apimachinery/pkg/util/sets"
+	promext "k8s.io/component-base/metrics/prometheusextension"
 )
 
 var (
@@ -189,6 +190,54 @@ func (o *HistogramOpts) toPromHistogramOpts() prometheus.HistogramOpts {
 	}
 }
 
+// TimingHistogramOpts bundles the options for creating a TimingHistogram metric. It is
+// mandatory to set Name to a non-empty string. All other fields are optional
+// and can safely be left at their zero value, although it is strongly
+// encouraged to set a Help string.
+type TimingHistogramOpts struct {
+	Namespace            string
+	Subsystem            string
+	Name                 string
+	Help                 string
+	ConstLabels          map[string]string
+	Buckets              []float64
+	InitialValue         float64
+	DeprecatedVersion    string
+	deprecateOnce        sync.Once
+	annotateOnce         sync.Once
+	StabilityLevel       StabilityLevel
+	LabelValueAllowLists *MetricLabelAllowList
+}
+
+// Modify help description on the metric description.
+func (o *TimingHistogramOpts) markDeprecated() {
+	o.deprecateOnce.Do(func() {
+		o.Help = fmt.Sprintf("(Deprecated since %v) %v", o.DeprecatedVersion, o.Help)
+	})
+}
+
+// annotateStabilityLevel annotates help description on the metric description with the stability level
+// of the metric
+func (o *TimingHistogramOpts) annotateStabilityLevel() {
+	o.annotateOnce.Do(func() {
+		o.Help = fmt.Sprintf("[%v] %v", o.StabilityLevel, o.Help)
+	})
+}
+
+// convenience function to allow easy transformation to the prometheus
+// counterpart. This will do more once we have a proper label abstraction
+func (o *TimingHistogramOpts) toPromHistogramOpts() promext.TimingHistogramOpts {
+	return promext.TimingHistogramOpts{
+		Namespace:    o.Namespace,
+		Subsystem:    o.Subsystem,
+		Name:         o.Name,
+		Help:         o.Help,
+		ConstLabels:  o.ConstLabels,
+		Buckets:      o.Buckets,
+		InitialValue: o.InitialValue,
+	}
+}
+
 // SummaryOpts bundles the options for creating a Summary metric. It is
 // mandatory to set Name to a non-empty string. While all other fields are
 // optional and can safely be left at their zero value, it is recommended to set

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

@@ -0,0 +1,268 @@
+/*
+Copyright 2019 The Kubernetes 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 metrics
+
+import (
+	"context"
+	"time"
+
+	"github.com/blang/semver/v4"
+	promext "k8s.io/component-base/metrics/prometheusextension"
+)
+
+// TimingHistogram is our internal representation for our wrapping struct around timing
+// histograms. It implements both kubeCollector and GaugeMetric
+type TimingHistogram struct {
+	GaugeMetric
+	*TimingHistogramOpts
+	nowFunc func() time.Time
+	lazyMetric
+	selfCollector
+}
+
+// NewTimingHistogram returns an object which is TimingHistogram-like. However, nothing
+// will be measured until the histogram is registered somewhere.
+func NewTimingHistogram(opts *TimingHistogramOpts) *TimingHistogram {
+	return NewTestableTimingHistogram(time.Now, opts)
+}
+
+// NewTestableTimingHistogram adds injection of the clock
+func NewTestableTimingHistogram(nowFunc func() time.Time, opts *TimingHistogramOpts) *TimingHistogram {
+	opts.StabilityLevel.setDefaults()
+
+	h := &TimingHistogram{
+		TimingHistogramOpts: opts,
+		nowFunc:             nowFunc,
+		lazyMetric:          lazyMetric{},
+	}
+	h.setPrometheusHistogram(noopMetric{})
+	h.lazyInit(h, BuildFQName(opts.Namespace, opts.Subsystem, opts.Name))
+	return h
+}
+
+// setPrometheusHistogram sets the underlying KubeGauge object, i.e. the thing that does the measurement.
+func (h *TimingHistogram) setPrometheusHistogram(histogram promext.TimingHistogram) {
+	h.GaugeMetric = histogram
+	h.initSelfCollection(histogram)
+}
+
+// DeprecatedVersion returns a pointer to the Version or nil
+func (h *TimingHistogram) DeprecatedVersion() *semver.Version {
+	return parseSemver(h.TimingHistogramOpts.DeprecatedVersion)
+}
+
+// initializeMetric invokes the actual prometheus.Histogram object instantiation
+// and stores a reference to it
+func (h *TimingHistogram) initializeMetric() {
+	h.TimingHistogramOpts.annotateStabilityLevel()
+	// this actually creates the underlying prometheus gauge.
+	histogram, err := promext.NewTestableTimingHistogram(h.nowFunc, h.TimingHistogramOpts.toPromHistogramOpts())
+	if err != nil {
+		panic(err) // handle as for regular histograms
+	}
+	h.setPrometheusHistogram(histogram)
+}
+
+// initializeDeprecatedMetric invokes the actual prometheus.Histogram object instantiation
+// but modifies the Help description prior to object instantiation.
+func (h *TimingHistogram) initializeDeprecatedMetric() {
+	h.TimingHistogramOpts.markDeprecated()
+	h.initializeMetric()
+}
+
+// WithContext allows the normal TimingHistogram metric to pass in context. The context is no-op now.
+func (h *TimingHistogram) WithContext(ctx context.Context) GaugeMetric {
+	return h.GaugeMetric
+}
+
+// timingHistogramVec is the internal representation of our wrapping struct around prometheus
+// TimingHistogramVecs.
+type timingHistogramVec struct {
+	*promext.TimingHistogramVec
+	*TimingHistogramOpts
+	nowFunc func() time.Time
+	lazyMetric
+	originalLabels []string
+}
+
+// NewTimingHistogramVec returns an object which satisfies kubeCollector and
+// wraps the promext.timingHistogramVec object.  Note well the way that
+// behavior depends on registration and whether this is hidden.
+func NewTimingHistogramVec(opts *TimingHistogramOpts, labels []string) PreContextAndRegisterableGaugeMetricVec {
+	return NewTestableTimingHistogramVec(time.Now, opts, labels)
+}
+
+// NewTestableTimingHistogramVec adds injection of the clock.
+func NewTestableTimingHistogramVec(nowFunc func() time.Time, opts *TimingHistogramOpts, labels []string) PreContextAndRegisterableGaugeMetricVec {
+	opts.StabilityLevel.setDefaults()
+
+	fqName := BuildFQName(opts.Namespace, opts.Subsystem, opts.Name)
+	allowListLock.RLock()
+	if allowList, ok := labelValueAllowLists[fqName]; ok {
+		opts.LabelValueAllowLists = allowList
+	}
+	allowListLock.RUnlock()
+
+	v := &timingHistogramVec{
+		TimingHistogramVec:  noopTimingHistogramVec,
+		TimingHistogramOpts: opts,
+		nowFunc:             nowFunc,
+		originalLabels:      labels,
+		lazyMetric:          lazyMetric{},
+	}
+	v.lazyInit(v, fqName)
+	return v
+}
+
+// DeprecatedVersion returns a pointer to the Version or nil
+func (v *timingHistogramVec) DeprecatedVersion() *semver.Version {
+	return parseSemver(v.TimingHistogramOpts.DeprecatedVersion)
+}
+
+func (v *timingHistogramVec) initializeMetric() {
+	v.TimingHistogramOpts.annotateStabilityLevel()
+	v.TimingHistogramVec = promext.NewTestableTimingHistogramVec(v.nowFunc, v.TimingHistogramOpts.toPromHistogramOpts(), v.originalLabels...)
+}
+
+func (v *timingHistogramVec) initializeDeprecatedMetric() {
+	v.TimingHistogramOpts.markDeprecated()
+	v.initializeMetric()
+}
+
+func (v *timingHistogramVec) Set(value float64, labelValues ...string) {
+	gm, _ := v.WithLabelValues(labelValues...)
+	gm.Set(value)
+}
+
+func (v *timingHistogramVec) Inc(labelValues ...string) {
+	gm, _ := v.WithLabelValues(labelValues...)
+	gm.Inc()
+}
+
+func (v *timingHistogramVec) Dec(labelValues ...string) {
+	gm, _ := v.WithLabelValues(labelValues...)
+	gm.Dec()
+}
+
+func (v *timingHistogramVec) Add(delta float64, labelValues ...string) {
+	gm, _ := v.WithLabelValues(labelValues...)
+	gm.Add(delta)
+}
+func (v *timingHistogramVec) SetToCurrentTime(labelValues ...string) {
+	gm, _ := v.WithLabelValues(labelValues...)
+	gm.SetToCurrentTime()
+}
+
+func (v *timingHistogramVec) SetForLabels(value float64, labels map[string]string) {
+	gm, _ := v.With(labels)
+	gm.Set(value)
+}
+
+func (v *timingHistogramVec) IncForLabels(labels map[string]string) {
+	gm, _ := v.With(labels)
+	gm.Inc()
+}
+
+func (v *timingHistogramVec) DecForLabels(labels map[string]string) {
+	gm, _ := v.With(labels)
+	gm.Dec()
+}
+
+func (v *timingHistogramVec) AddForLabels(delta float64, labels map[string]string) {
+	gm, _ := v.With(labels)
+	gm.Add(delta)
+}
+func (v *timingHistogramVec) SetToCurrentTimeForLabels(labels map[string]string) {
+	gm, _ := v.With(labels)
+	gm.SetToCurrentTime()
+}
+
+// WithLabelValues, if called after this vector has been
+// registered in at least one registry and this vector is not
+// hidden, will return a GaugeMetric that is NOT a noop along
+// with nil error.  If called on a hidden vector then it will
+// return a noop and a nil error.  Otherwise it returns a noop
+// and an error that passes ErrIsNotReady.
+func (v *timingHistogramVec) WithLabelValues(lvs ...string) (GaugeMetric, error) {
+	if v.IsHidden() {
+		return noop, nil
+	}
+	if !v.IsCreated() {
+		return noop, errNotReady
+	}
+	if v.LabelValueAllowLists != nil {
+		v.LabelValueAllowLists.ConstrainToAllowedList(v.originalLabels, lvs)
+	}
+	return v.TimingHistogramVec.WithLabelValues(lvs...).(GaugeMetric), nil
+}
+
+// With, if called after this vector has been
+// registered in at least one registry and this vector is not
+// hidden, will return a GaugeMetric that is NOT a noop along
+// with nil error.  If called on a hidden vector then it will
+// return a noop and a nil error.  Otherwise it returns a noop
+// and an error that passes ErrIsNotReady.
+func (v *timingHistogramVec) With(labels map[string]string) (GaugeMetric, error) {
+	if v.IsHidden() {
+		return noop, nil
+	}
+	if !v.IsCreated() {
+		return noop, errNotReady
+	}
+	if v.LabelValueAllowLists != nil {
+		v.LabelValueAllowLists.ConstrainLabelMap(labels)
+	}
+	return v.TimingHistogramVec.With(labels).(GaugeMetric), nil
+}
+
+// Delete deletes the metric where the variable labels are the same as those
+// passed in as labels. It returns true if a metric was deleted.
+//
+// It is not an error if the number and names of the Labels are inconsistent
+// 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 {
+	if !v.IsCreated() {
+		return false // since we haven't created the metric, we haven't deleted a metric with the passed in values
+	}
+	return v.TimingHistogramVec.Delete(labels)
+}
+
+// Reset deletes all metrics in this vector.
+func (v *timingHistogramVec) Reset() {
+	if !v.IsCreated() {
+		return
+	}
+
+	v.TimingHistogramVec.Reset()
+}
+
+// WithContext returns wrapped timingHistogramVec with context
+func (v *timingHistogramVec) WithContext(ctx context.Context) GaugeMetricVec {
+	return &TimingHistogramVecWithContext{
+		ctx:                ctx,
+		timingHistogramVec: v,
+	}
+}
+
+// TimingHistogramVecWithContext is the wrapper of timingHistogramVec with context.
+// Currently the context is ignored.
+type TimingHistogramVecWithContext struct {
+	*timingHistogramVec
+	ctx context.Context
+}

staging/src/k8s.io/component-base/metrics/timing_histogram_test.go

@@ -0,0 +1,370 @@
+/*
+Copyright 2019 The Kubernetes 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 metrics
+
+import (
+	"testing"
+	"time"
+
+	"github.com/blang/semver/v4"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/assert"
+
+	apimachineryversion "k8s.io/apimachinery/pkg/version"
+	testclock "k8s.io/utils/clock/testing"
+)
+
+func TestTimingHistogram(t *testing.T) {
+	v115 := semver.MustParse("1.15.0")
+	var tests = []struct {
+		desc string
+		*TimingHistogramOpts
+		registryVersion     *semver.Version
+		expectedMetricCount int
+		expectedHelp        string
+	}{
+		{
+			desc: "Test non deprecated",
+			TimingHistogramOpts: &TimingHistogramOpts{
+				Namespace:    "namespace",
+				Name:         "metric_test_name",
+				Subsystem:    "subsystem",
+				Help:         "histogram help message",
+				Buckets:      DefBuckets,
+				InitialValue: 13,
+			},
+			registryVersion:     &v115,
+			expectedMetricCount: 1,
+			expectedHelp:        "EXPERIMENTAL: [ALPHA] histogram help message",
+		},
+		{
+			desc: "Test deprecated",
+			TimingHistogramOpts: &TimingHistogramOpts{
+				Namespace:         "namespace",
+				Name:              "metric_test_name",
+				Subsystem:         "subsystem",
+				Help:              "histogram help message",
+				DeprecatedVersion: "1.15.0",
+				Buckets:           DefBuckets,
+				InitialValue:      3,
+			},
+			registryVersion:     &v115,
+			expectedMetricCount: 1,
+			expectedHelp:        "EXPERIMENTAL: [ALPHA] (Deprecated since 1.15.0) histogram help message",
+		},
+		{
+			desc: "Test hidden",
+			TimingHistogramOpts: &TimingHistogramOpts{
+				Namespace:         "namespace",
+				Name:              "metric_test_name",
+				Subsystem:         "subsystem",
+				Help:              "histogram help message",
+				DeprecatedVersion: "1.14.0",
+				Buckets:           DefBuckets,
+				InitialValue:      5,
+			},
+			registryVersion:     &v115,
+			expectedMetricCount: 0,
+			expectedHelp:        "EXPERIMENTAL: histogram help message",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			registry := newKubeRegistry(apimachineryversion.Info{
+				Major:      "1",
+				Minor:      "15",
+				GitVersion: "v1.15.0-alpha-1.12345",
+			})
+			t0 := time.Now()
+			clk := testclock.NewFakePassiveClock(t0)
+			c := NewTestableTimingHistogram(clk.Now, test.TimingHistogramOpts)
+			registry.MustRegister(c)
+
+			metricChan := make(chan prometheus.Metric)
+			go func() {
+				c.Collect(metricChan)
+				close(metricChan)
+			}()
+			m1 := <-metricChan
+			gm1, ok := m1.(GaugeMetric)
+			if !ok || gm1 != c.GaugeMetric {
+				t.Error("Unexpected metric", m1, c.GaugeMetric)
+			}
+			m2, ok := <-metricChan
+			if ok {
+				t.Error("Unexpected second metric", m2)
+			}
+
+			ms, err := registry.Gather()
+			assert.Equalf(t, test.expectedMetricCount, len(ms), "Got %v metrics, Want: %v metrics", len(ms), test.expectedMetricCount)
+			assert.Nil(t, err, "Gather failed %v", err)
+
+			for _, metric := range ms {
+				assert.Equalf(t, test.expectedHelp, metric.GetHelp(), "Got %s as help message, want %s", metric.GetHelp(), test.expectedHelp)
+			}
+
+			// let's exercise the metric and check that it still works
+			v0 := test.TimingHistogramOpts.InitialValue
+			dt1 := time.Nanosecond
+			t1 := t0.Add(dt1)
+			clk.SetTime(t1)
+			var v1 float64 = 10
+			c.Set(v1)
+			dt2 := time.Hour
+			t2 := t1.Add(dt2)
+			clk.SetTime(t2)
+			var v2 float64 = 1e6
+			c.Add(v2 - v1)
+			dt3 := time.Microsecond
+			t3 := t2.Add(dt3)
+			clk.SetTime(t3)
+			c.Set(0)
+			expectedCount := uint64(dt1 + dt2 + dt3)
+			expectedSum := float64(dt1)*v0 + float64(dt2)*v1 + float64(dt3)*v2
+			ms, err = registry.Gather()
+			assert.Nil(t, err, "Gather failed %v", err)
+
+			for _, mf := range ms {
+				t.Logf("Considering metric family %s", mf.GetName())
+				for _, m := range mf.GetMetric() {
+					assert.Equalf(t, expectedCount, m.GetHistogram().GetSampleCount(), "Got %v, want %v as the sample count of metric %s", m.GetHistogram().GetSampleCount(), expectedCount, m.String())
+					assert.Equalf(t, expectedSum, m.GetHistogram().GetSampleSum(), "Got %v, want %v as the sample sum of metric %s", m.GetHistogram().GetSampleSum(), expectedSum, m.String())
+				}
+			}
+		})
+	}
+}
+
+func TestTimingHistogramVec(t *testing.T) {
+	v115 := semver.MustParse("1.15.0")
+	var tests = []struct {
+		desc string
+		*TimingHistogramOpts
+		labels              []string
+		registryVersion     *semver.Version
+		expectedMetricCount int
+		expectedHelp        string
+	}{
+		{
+			desc: "Test non deprecated",
+			TimingHistogramOpts: &TimingHistogramOpts{
+				Namespace:    "namespace",
+				Name:         "metric_test_name",
+				Subsystem:    "subsystem",
+				Help:         "histogram help message",
+				Buckets:      DefBuckets,
+				InitialValue: 5,
+			},
+			labels:              []string{"label_a", "label_b"},
+			registryVersion:     &v115,
+			expectedMetricCount: 1,
+			expectedHelp:        "EXPERIMENTAL: [ALPHA] histogram help message",
+		},
+		{
+			desc: "Test deprecated",
+			TimingHistogramOpts: &TimingHistogramOpts{
+				Namespace:         "namespace",
+				Name:              "metric_test_name",
+				Subsystem:         "subsystem",
+				Help:              "histogram help message",
+				DeprecatedVersion: "1.15.0",
+				Buckets:           DefBuckets,
+				InitialValue:      13,
+			},
+			labels:              []string{"label_a", "label_b"},
+			registryVersion:     &v115,
+			expectedMetricCount: 1,
+			expectedHelp:        "EXPERIMENTAL: [ALPHA] (Deprecated since 1.15.0) histogram help message",
+		},
+		{
+			desc: "Test hidden",
+			TimingHistogramOpts: &TimingHistogramOpts{
+				Namespace:         "namespace",
+				Name:              "metric_test_name",
+				Subsystem:         "subsystem",
+				Help:              "histogram help message",
+				DeprecatedVersion: "1.14.0",
+				Buckets:           DefBuckets,
+				InitialValue:      42,
+			},
+			labels:              []string{"label_a", "label_b"},
+			registryVersion:     &v115,
+			expectedMetricCount: 0,
+			expectedHelp:        "EXPERIMENTAL: histogram help message",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			registry := newKubeRegistry(apimachineryversion.Info{
+				Major:      "1",
+				Minor:      "15",
+				GitVersion: "v1.15.0-alpha-1.12345",
+			})
+			t0 := time.Now()
+			clk := testclock.NewFakePassiveClock(t0)
+			c := NewTestableTimingHistogramVec(clk.Now, test.TimingHistogramOpts, test.labels)
+			registry.MustRegister(c)
+			var v0 float64 = 3
+			cm1, err := c.WithLabelValues("1", "2")
+			if err != nil {
+				t.Error(err)
+			}
+			cm1.Set(v0)
+
+			if test.expectedMetricCount > 0 {
+				metricChan := make(chan prometheus.Metric, 2)
+				c.Collect(metricChan)
+				close(metricChan)
+				m1 := <-metricChan
+				if m1 != cm1.(prometheus.Metric) {
+					t.Error("Unexpected metric", m1, cm1)
+				}
+				m2, ok := <-metricChan
+				if ok {
+					t.Error("Unexpected second metric", m2)
+				}
+			}
+
+			ms, err := registry.Gather()
+			assert.Equalf(t, test.expectedMetricCount, len(ms), "Got %v metrics, Want: %v metrics", len(ms), test.expectedMetricCount)
+			assert.Nil(t, err, "Gather failed %v", err)
+			for _, metric := range ms {
+				if metric.GetHelp() != test.expectedHelp {
+					assert.Equalf(t, test.expectedHelp, metric.GetHelp(), "Got %s as help message, want %s", metric.GetHelp(), test.expectedHelp)
+				}
+			}
+
+			// let's exercise the metric and verify it still works
+			c.Set(v0, "1", "3")
+			c.Set(v0, "2", "3")
+			dt1 := time.Nanosecond
+			t1 := t0.Add(dt1)
+			clk.SetTime(t1)
+			c.Add(5.0, "1", "2")
+			c.Add(5.0, "1", "3")
+			c.Add(5.0, "2", "3")
+			ms, err = registry.Gather()
+			assert.Nil(t, err, "Gather failed %v", err)
+
+			for _, mf := range ms {
+				t.Logf("Considering metric family %s", mf.String())
+				assert.Equalf(t, 3, len(mf.GetMetric()), "Got %v metrics, wanted 3 as the count for family %#+v", len(mf.GetMetric()), mf)
+				for _, m := range mf.GetMetric() {
+					expectedCount := uint64(dt1)
+					expectedSum := float64(dt1) * v0
+					assert.Equalf(t, expectedCount, m.GetHistogram().GetSampleCount(), "Got %v, expected histogram sample count to equal %d for metric %s", m.GetHistogram().GetSampleCount(), expectedCount, m.String())
+					assert.Equalf(t, expectedSum, m.GetHistogram().GetSampleSum(), "Got %v, expected histogram sample sum to equal %v for metric %s", m.GetHistogram().GetSampleSum(), expectedSum, m.String())
+				}
+			}
+		})
+	}
+}
+
+func TestTimingHistogramWithLabelValueAllowList(t *testing.T) {
+	labelAllowValues := map[string]string{
+		"namespace_subsystem_metric_allowlist_test,label_a": "allowed",
+	}
+	labels := []string{"label_a", "label_b"}
+	opts := &TimingHistogramOpts{
+		Namespace:    "namespace",
+		Name:         "metric_allowlist_test",
+		Subsystem:    "subsystem",
+		InitialValue: 7,
+	}
+	var tests = []struct {
+		desc               string
+		labelValues        [][]string
+		expectMetricValues map[string]uint64
+	}{
+		{
+			desc:        "Test no unexpected input",
+			labelValues: [][]string{{"allowed", "b1"}, {"allowed", "b2"}},
+			expectMetricValues: map[string]uint64{
+				"allowed b1": 1.0,
+				"allowed b2": 1.0,
+			},
+		},
+		{
+			desc:        "Test unexpected input",
+			labelValues: [][]string{{"allowed", "b1"}, {"not_allowed", "b1"}},
+			expectMetricValues: map[string]uint64{
+				"allowed b1":    1.0,
+				"unexpected b1": 1.0,
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			SetLabelAllowListFromCLI(labelAllowValues)
+			registry := newKubeRegistry(apimachineryversion.Info{
+				Major:      "1",
+				Minor:      "15",
+				GitVersion: "v1.15.0-alpha-1.12345",
+			})
+			t0 := time.Now()
+			clk := testclock.NewFakePassiveClock(t0)
+			c := NewTestableTimingHistogramVec(clk.Now, opts, labels)
+			registry.MustRegister(c)
+			var v0 float64 = 13
+			for _, lv := range test.labelValues {
+				c.Set(v0, lv...)
+			}
+
+			dt1 := 3 * time.Hour
+			t1 := t0.Add(dt1)
+			clk.SetTime(t1)
+
+			for _, lv := range test.labelValues {
+				c.Add(1.0, lv...)
+			}
+			mfs, err := registry.Gather()
+			assert.Nil(t, err, "Gather failed %v", err)
+
+			for _, mf := range mfs {
+				if *mf.Name != BuildFQName(opts.Namespace, opts.Subsystem, opts.Name) {
+					continue
+				}
+				mfMetric := mf.GetMetric()
+				t.Logf("Consider metric family %s", mf.GetName())
+
+				for _, m := range mfMetric {
+					var aValue, bValue string
+					for _, l := range m.Label {
+						if *l.Name == "label_a" {
+							aValue = *l.Value
+						}
+						if *l.Name == "label_b" {
+							bValue = *l.Value
+						}
+					}
+					labelValuePair := aValue + " " + bValue
+					expectedCount, ok := test.expectMetricValues[labelValuePair]
+					assert.True(t, ok, "Got unexpected label values, lable_a is %v, label_b is %v", aValue, bValue)
+					expectedSum := float64(dt1) * v0 * float64(expectedCount)
+					expectedCount *= uint64(dt1)
+					actualCount := m.GetHistogram().GetSampleCount()
+					actualSum := m.GetHistogram().GetSampleSum()
+					assert.Equalf(t, expectedCount, actualCount, "Got %v, wanted %v as the count while setting label_a to %v and label b to %v", actualCount, expectedCount, aValue, bValue)
+					assert.Equalf(t, expectedSum, actualSum, "Got %v, wanted %v as the sum while setting label_a to %v and label b to %v", actualSum, expectedSum, aValue, bValue)
+				}
+			}
+		})
+	}
+}

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

@@ -17,6 +17,9 @@ limitations under the License.
 package metrics
 
 import (
+	"context"
+	"errors"
+
 	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
 )
@@ -65,6 +68,70 @@ 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 {
+	Set(value float64, labelValues ...string)
+	Inc(labelValues ...string)
+	Dec(labelValues ...string)
+	Add(delta float64, labelValues ...string)
+	SetToCurrentTime(labelValues ...string)
+
+	SetForLabels(value float64, labels map[string]string)
+	IncForLabels(labels map[string]string)
+	DecForLabels(labels map[string]string)
+	AddForLabels(delta float64, labels map[string]string)
+	SetToCurrentTimeForLabels(labels map[string]string)
+
+	// WithLabelValues, if called after this vector has been
+	// registered in at least one registry and this vector is not
+	// hidden, will return a GaugeMetric that is NOT a noop along
+	// with nil error.  If called on a hidden vector then it will
+	// return a noop and a nil error.  Otherwise it returns a noop
+	// and an error that passes ErrIsNotReady.
+	WithLabelValues(labelValues ...string) (GaugeMetric, error)
+
+	// With, if called after this vector has been
+	// registered in at least one registry and this vector is not
+	// hidden, will return a GaugeMetric that is NOT a noop along
+	// with nil error.  If called on a hidden vector then it will
+	// return a noop and a nil error.  Otherwise it returns a noop
+	// and an error that passes ErrIsNotReady.
+	With(labels map[string]string) (GaugeMetric, error)
+
+	// Delete asserts that the vec should have no member for the given label set.
+	// The returned bool indicates whether there was a change.
+	// The return will certainly be `false` if the given label set has the wrong
+	// set of label names.
+	Delete(map[string]string) bool
+
+	// Reset removes all the members
+	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)
@@ -93,3 +160,9 @@ type GaugeFunc interface {
 	Metric
 	Collector
 }
+
+func ErrIsNotReady(err error) bool {
+	return err == errNotReady
+}
+
+var errNotReady = errors.New("metric vec is not registered yet")

vendor/modules.txt

@@ -1954,6 +1954,7 @@ k8s.io/component-base/metrics/prometheus/ratelimiter
 k8s.io/component-base/metrics/prometheus/restclient
 k8s.io/component-base/metrics/prometheus/version
 k8s.io/component-base/metrics/prometheus/workqueue
+k8s.io/component-base/metrics/prometheusextension
 k8s.io/component-base/metrics/testutil
 k8s.io/component-base/term
 k8s.io/component-base/traces