Merge pull request kubernetes#87923 from ingvagabund/move-direct-prometheus-metrics-under-component-base-metrics

Collect some of scheduling metrics and scheduling throughput (vol. 2)

Author: k8s-ci-robot

staging/src/k8s.io/component-base/metrics/testutil/BUILD

@@ -13,6 +13,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/version:go_default_library",
         "//staging/src/k8s.io/component-base/metrics:go_default_library",
         "//vendor/github.com/prometheus/client_golang/prometheus/testutil:go_default_library",
+        "//vendor/github.com/prometheus/client_model/go:go_default_library",
         "//vendor/github.com/prometheus/common/expfmt:go_default_library",
         "//vendor/github.com/prometheus/common/model:go_default_library",
     ],
@@ -34,7 +35,14 @@ filegroup(
 
 go_test(
     name = "go_default_test",
-    srcs = ["testutil_test.go"],
+    srcs = [
+        "metrics_test.go",
+        "testutil_test.go",
+    ],
     embed = [":go_default_library"],
-    deps = ["//staging/src/k8s.io/component-base/metrics:go_default_library"],
+    deps = [
+        "//staging/src/k8s.io/component-base/metrics:go_default_library",
+        "//vendor/github.com/prometheus/client_model/go:go_default_library",
+        "//vendor/k8s.io/utils/pointer:go_default_library",
+    ],
 )

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

@@ -19,11 +19,16 @@ package testutil
 import (
 	"fmt"
 	"io"
+	"math"
 	"reflect"
+	"sort"
 	"strings"
 
+	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/expfmt"
 	"github.com/prometheus/common/model"
+
+	"k8s.io/component-base/metrics"
 )
 
 var (
@@ -178,3 +183,140 @@ func ValidateMetrics(metrics Metrics, metricName string, expectedLabels ...strin
 	}
 	return nil
 }
+
+// Histogram wraps prometheus histogram DTO (data transfer object)
+type Histogram struct {
+	*dto.Histogram
+}
+
+// GetHistogramFromGatherer collects a metric from a gatherer implementing k8s.io/component-base/metrics.Gatherer interface.
+// Used only for testing purposes where we need to gather metrics directly from a running binary (without metrics endpoint).
+func GetHistogramFromGatherer(gatherer metrics.Gatherer, metricName string) (Histogram, error) {
+	var metricFamily *dto.MetricFamily
+	m, err := gatherer.Gather()
+	if err != nil {
+		return Histogram{}, err
+	}
+	for _, mFamily := range m {
+		if mFamily.Name != nil && *mFamily.Name == metricName {
+			metricFamily = mFamily
+			break
+		}
+	}
+
+	if metricFamily == nil {
+		return Histogram{}, fmt.Errorf("Metric %q not found", metricName)
+	}
+
+	if metricFamily.GetMetric() == nil {
+		return Histogram{}, fmt.Errorf("Metric %q is empty", metricName)
+	}
+
+	if len(metricFamily.GetMetric()) == 0 {
+		return Histogram{}, fmt.Errorf("Metric %q is empty", metricName)
+	}
+
+	return Histogram{
+		// Histograms are stored under the first index (based on observation).
+		// Given there's only one histogram registered per each metric name, accessing
+		// the first index is sufficient.
+		metricFamily.GetMetric()[0].GetHistogram(),
+	}, nil
+}
+
+func uint64Ptr(u uint64) *uint64 {
+	return &u
+}
+
+// Bucket of a histogram
+type bucket struct {
+	upperBound float64
+	count      float64
+}
+
+func bucketQuantile(q float64, buckets []bucket) float64 {
+	if q < 0 {
+		return math.Inf(-1)
+	}
+	if q > 1 {
+		return math.Inf(+1)
+	}
+
+	if len(buckets) < 2 {
+		return math.NaN()
+	}
+
+	rank := q * buckets[len(buckets)-1].count
+	b := sort.Search(len(buckets)-1, func(i int) bool { return buckets[i].count >= rank })
+
+	if b == 0 {
+		return buckets[0].upperBound * (rank / buckets[0].count)
+	}
+
+	// linear approximation of b-th bucket
+	brank := rank - buckets[b-1].count
+	bSize := buckets[b].upperBound - buckets[b-1].upperBound
+	bCount := buckets[b].count - buckets[b-1].count
+
+	return buckets[b-1].upperBound + bSize*(brank/bCount)
+}
+
+// Quantile computes q-th quantile of a cumulative histogram.
+// It's expected the histogram is valid (by calling Validate)
+func (hist *Histogram) Quantile(q float64) float64 {
+	buckets := []bucket{}
+
+	for _, bckt := range hist.Bucket {
+		buckets = append(buckets, bucket{
+			count:      float64(*bckt.CumulativeCount),
+			upperBound: *bckt.UpperBound,
+		})
+	}
+
+	// bucketQuantile expects the upper bound of the last bucket to be +inf
+	// buckets[len(buckets)-1].upperBound = math.Inf(+1)
+
+	return bucketQuantile(q, buckets)
+}
+
+// Average computes histogram's average value
+func (hist *Histogram) Average() float64 {
+	return *hist.SampleSum / float64(*hist.SampleCount)
+}
+
+// Clear clears all fields of the wrapped histogram
+func (hist *Histogram) Clear() {
+	if hist.SampleCount != nil {
+		*hist.SampleCount = 0
+	}
+	if hist.SampleSum != nil {
+		*hist.SampleSum = 0
+	}
+	for _, b := range hist.Bucket {
+		if b.CumulativeCount != nil {
+			*b.CumulativeCount = 0
+		}
+	}
+}
+
+// Validate makes sure the wrapped histogram has all necessary fields set and with valid values.
+func (hist *Histogram) Validate() error {
+	if hist.SampleCount == nil || *hist.SampleCount == 0 {
+		return fmt.Errorf("nil or empty histogram SampleCount")
+	}
+
+	if hist.SampleSum == nil || *hist.SampleSum == 0 {
+		return fmt.Errorf("nil or empty histogram SampleSum")
+	}
+
+	for _, bckt := range hist.Bucket {
+		if bckt == nil {
+			return fmt.Errorf("empty histogram bucket")
+		}
+		if bckt.UpperBound == nil || *bckt.UpperBound < 0 {
+			return fmt.Errorf("nil or negative histogram bucket UpperBound")
+		}
+	}
+
+	return nil
+}