Add wrapper for TimingHistogram

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

Kubernetes-commit: 68d92494907ae1d8a87b2e29cc9cc2a2709ca3a9

metrics/histogram.go

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

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)
@@ -218,20 +248,20 @@ 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,
 			},
 		},
 		{
 			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)
 				}
 			}

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{}
 

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