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quantile: if the last upper bound is +Inf, return the previous upper bound

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In case the last upper bound is +Inf, computed quantile is +Inf as well.
Given there's no restriction on how far individual upper bounds are from each other,
cut the last interval and consider the second last upper bound as the final one.
This commit is contained in:
Jan Chaloupka 2020-03-31 18:41:42 +02:00
parent 7b1a531976
commit e410b837dc
2 changed files with 37 additions and 21 deletions
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4
staging/src/k8s.io/component-base/metrics/testutil/metrics.go
View File

@ -262,6 +262,10 @@ func bucketQuantile(q float64, buckets []bucket) float64 {
return buckets[0].upperBound * (rank / buckets[0].count)
}
if b == len(buckets)-1 && math.IsInf(buckets[b].upperBound, 1) {
return buckets[len(buckets)-2].upperBound
}
// linear approximation of b-th bucket
brank := rank - buckets[b-1].count
bSize := buckets[b].upperBound - buckets[b-1].upperBound

54
staging/src/k8s.io/component-base/metrics/testutil/metrics_test.go
View File

@ -18,6 +18,7 @@ package testutil
import (
"fmt"
"math"
"testing"
"k8s.io/utils/pointer"
@ -54,6 +55,7 @@ func samples2Histogram(samples []float64, upperBounds []float64) Histogram {
func TestHistogramQuantile(t *testing.T) {
tests := []struct {
name string
samples []float64
bounds []float64
q50 float64
@ -61,7 +63,7 @@ func TestHistogramQuantile(t *testing.T) {
q99 float64
}{
{
// repeating numbers
name: "Repeating numbers",
samples: []float64{0.5, 0.5, 0.5, 0.5, 1.5, 1.5, 1.5, 1.5, 3, 3, 3, 3, 6, 6, 6, 6},
bounds: []float64{1, 2, 4, 8},
q50: 2,
@ -69,7 +71,7 @@ func TestHistogramQuantile(t *testing.T) {
q99: 7.84,
},
{
// random numbers
name: "Random numbers",
samples: []float64{11, 67, 61, 21, 40, 36, 52, 63, 8, 3, 67, 35, 61, 1, 36, 58},
bounds: []float64{10, 20, 40, 80},
q50: 40,
@ -77,35 +79,45 @@ func TestHistogramQuantile(t *testing.T) {
q99: 79.2,
},
{
// the last bucket is empty
name: "The last bucket is empty",
samples: []float64{6, 34, 30, 10, 20, 18, 26, 31, 4, 2, 33, 17, 30, 1, 18, 29},
bounds: []float64{10, 20, 40, 80},
q50: 20,
q90: 36,
q99: 39.6,
},
{
name: "The last bucket has positive infinity upper bound",
samples: []float64{5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 500},
bounds: []float64{10, 20, 40, math.Inf(1)},
q50: 5.3125,
q90: 9.5625,
q99: 40,
},
}
for _, test := range tests {
h := samples2Histogram(test.samples, test.bounds)
q50 := h.Quantile(0.5)
q90 := h.Quantile(0.9)
q99 := h.Quantile(0.99)
q999999 := h.Quantile(0.999999)
t.Run(test.name, func(t *testing.T) {
h := samples2Histogram(test.samples, test.bounds)
q50 := h.Quantile(0.5)
q90 := h.Quantile(0.9)
q99 := h.Quantile(0.99)
q999999 := h.Quantile(0.999999)
if q50 != test.q50 {
t.Errorf("Expected q50 to be %v, got %v instead", test.q50, q50)
}
if q90 != test.q90 {
t.Errorf("Expected q90 to be %v, got %v instead", test.q90, q90)
}
if q99 != test.q99 {
t.Errorf("Expected q99 to be %v, got %v instead", test.q99, q99)
}
lastUpperBound := test.bounds[len(test.bounds)-1]
if !(q999999 < lastUpperBound) {
t.Errorf("Expected q999999 to be less than %v, got %v instead", lastUpperBound, q999999)
}
if q50 != test.q50 {
t.Errorf("Expected q50 to be %v, got %v instead", test.q50, q50)
}
if q90 != test.q90 {
t.Errorf("Expected q90 to be %v, got %v instead", test.q90, q90)
}
if q99 != test.q99 {
t.Errorf("Expected q99 to be %v, got %v instead", test.q99, q99)
}
lastUpperBound := test.bounds[len(test.bounds)-1]
if !(q999999 < lastUpperBound) {
t.Errorf("Expected q999999 to be less than %v, got %v instead", lastUpperBound, q999999)
}
})
}
}