Add values to correct bucket

Signed-off-by: William Perron <[email protected]>

prometheus/examples_test.go

@@ -16,13 +16,14 @@ package prometheus_test
 import (
  "bytes"
  "fmt"
- "google.golang.org/protobuf/types/known/timestamppb"
  "math"
  "net/http"
  "runtime"
  "strings"
  "time"
 
+ "google.golang.org/protobuf/types/known/timestamppb"
+
  //nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
  "github.com/golang/protobuf/proto"
  "github.com/prometheus/common/expfmt"
@@ -556,12 +557,12 @@ func ExampleNewConstHistogram() {
  lp := dto.LabelPair{Name: &n, Value: &v}
  var labelPairs []*dto.LabelPair
  labelPairs = append(labelPairs, &lp)
- val := float64(42)
+ vals := []float64{24.0, 42.0, 89.0, 157.0}
  t, _ := time.Parse("unix", "Mon Jan _2 15:04:05 MST 2006")
  ts := timestamppb.New(t)
 
  for i := 0; i < 4; i++ {
- e := dto.Exemplar{Label: labelPairs, Value: &val, Timestamp: ts}
+ e := dto.Exemplar{Label: labelPairs, Value: &vals[i], Timestamp: ts}
  exemplars = append(exemplars, &e)
  }
 
@@ -605,7 +606,7 @@ func ExampleNewConstHistogram() {
  // name: "testName"
  // value: "testVal"
  // >
- // value: 42
+ // value: 24
  // timestamp: <
  // seconds: -62135596800
  // >
@@ -633,7 +634,7 @@ func ExampleNewConstHistogram() {
  // name: "testName"
  // value: "testVal"
  // >
- // value: 42
+ // value: 89
  // timestamp: <
  // seconds: -62135596800
  // >
@@ -647,7 +648,7 @@ func ExampleNewConstHistogram() {
  // name: "testName"
  // value: "testVal"
  // >
- // value: 42
+ // value: 157
  // timestamp: <
  // seconds: -62135596800
  // >

prometheus/histogram.go

@@ -582,7 +582,9 @@ func (h *constHistogram) Desc() *Desc {
 
 func (h *constHistogram) Write(out *dto.Metric) error {
  his := &dto.Histogram{}
+ // h.buckets, buckets and bounds are all the same length
  buckets := make([]*dto.Bucket, 0, len(h.buckets))
+ bounds := make([]float64, 0)
 
  his.SampleCount = proto.Uint64(h.count)
  his.SampleSum = proto.Float64(h.sum)
@@ -591,15 +593,24 @@ func (h *constHistogram) Write(out *dto.Metric) error {
  CumulativeCount: proto.Uint64(count),
  UpperBound: proto.Float64(upperBound),
  })
+ bounds = append(bounds, upperBound)
  }
 
+ // make sure that both bounds and buckets have the same ordering
  if len(buckets) > 0 {
  sort.Sort(buckSort(buckets))
  }
+ sort.Float64s(bounds)
 
  if len(h.exemplars) > 0 {
- for i := 0; i < len(buckets); i++ {
- buckets[i].Exemplar = h.exemplars[i]
+ r := len(buckets)
+ for i := 0; i < r; i++ {
+ bound := sort.SearchFloat64s(bounds, *h.exemplars[i].Value)
+ // Only append the exemplar if it's within the bounds defined in the
+ // buckets.
+ if bound < r {
+ buckets[bound].Exemplar = h.exemplars[i]
+ }
  }
  }