Add a Prometheus-compatible Histogram function, and convert the vmrange label to the le label

.gitignore

@@ -0,0 +1 @@
+.idea/

histogram.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"strings"
 	"sync"
 	"time"
 )
@@ -55,6 +56,8 @@ type Histogram struct {
 	upper uint64
 
 	sum float64
+
+	compatible bool
 }
 
 // Reset resets the given histogram.
@@ -149,7 +152,10 @@ func (h *Histogram) VisitNonZeroBuckets(f func(vmrange string, count uint64)) {
 //
 // The returned histogram is safe to use from concurrent goroutines.
 func NewHistogram(name string) *Histogram {
-	return defaultSet.NewHistogram(name)
+	return defaultSet.NewHistogram(name, false)
+}
+func NewCompatibleHistogram(name string) *Histogram {
+	return defaultSet.NewHistogram(name, true)
 }
 
 // GetOrCreateHistogram returns registered histogram with the given name
@@ -167,7 +173,10 @@ func NewHistogram(name string) *Histogram {
 //
 // Performance tip: prefer NewHistogram instead of GetOrCreateHistogram.
 func GetOrCreateHistogram(name string) *Histogram {
-	return defaultSet.GetOrCreateHistogram(name)
+	return defaultSet.GetOrCreateHistogram(name, false)
+}
+func GetOrCreateCompatibleHistogram(name string) *Histogram {
+	return defaultSet.GetOrCreateHistogram(name, true)
 }
 
 // UpdateDuration updates request duration based on the given startTime.
@@ -201,6 +210,10 @@ var (
 )
 
 func (h *Histogram) marshalTo(prefix string, w io.Writer) {
+	if h.compatible {
+		h.marshalToPrometheus(prefix, w)
+		return
+	}
 	countTotal := uint64(0)
 	h.VisitNonZeroBuckets(func(vmrange string, count uint64) {
 		tag := fmt.Sprintf("vmrange=%q", vmrange)
@@ -221,6 +234,41 @@ func (h *Histogram) marshalTo(prefix string, w io.Writer) {
 	}
 	fmt.Fprintf(w, "%s_count%s %d\n", name, labels, countTotal)
 }
+func (h *Histogram) marshalToPrometheus(prefix string, w io.Writer) {
+	countTotal := uint64(0)
+	inf := false
+	h.VisitNonZeroBuckets(func(vmrange string, count uint64) {
+		v := strings.Split(vmrange, "...")
+		if len(v) != 2 {
+			return
+		}
+		if v[1] == "+Inf" {
+			inf = true
+		}
+		tag := fmt.Sprintf("le=%q", v[1])
+		metricName := addTag(prefix, tag)
+		name, labels := splitMetricName(metricName)
+		countTotal += count
+		fmt.Fprintf(w, "%s_bucket%s %d\n", name, labels, countTotal)
+	})
+	if countTotal == 0 {
+		return
+	}
+	if !inf {
+		tag := fmt.Sprintf("le=%q", "+Inf")
+		metricName := addTag(prefix, tag)
+		name, labels := splitMetricName(metricName)
+		fmt.Fprintf(w, "%s_bucket%s %d\n", name, labels, countTotal)
+	}
+	name, labels := splitMetricName(prefix)
+	sum := h.getSum()
+	if float64(int64(sum)) == sum {
+		fmt.Fprintf(w, "%s_sum%s %d\n", name, labels, int64(sum))
+	} else {
+		fmt.Fprintf(w, "%s_sum%s %g\n", name, labels, sum)
+	}
+	fmt.Fprintf(w, "%s_count%s %d\n", name, labels, countTotal)
+}
 
 func (h *Histogram) getSum() float64 {
 	h.mu.Lock()

push.go

@@ -115,8 +115,8 @@ func InitPushExt(pushURL string, interval time.Duration, extraLabels string, wri
 	pushesTotal := pushMetrics.GetOrCreateCounter(fmt.Sprintf(`metrics_push_total{url=%q}`, pushURLRedacted))
 	pushErrorsTotal := pushMetrics.GetOrCreateCounter(fmt.Sprintf(`metrics_push_errors_total{url=%q}`, pushURLRedacted))
 	bytesPushedTotal := pushMetrics.GetOrCreateCounter(fmt.Sprintf(`metrics_push_bytes_pushed_total{url=%q}`, pushURLRedacted))
-	pushDuration := pushMetrics.GetOrCreateHistogram(fmt.Sprintf(`metrics_push_duration_seconds{url=%q}`, pushURLRedacted))
-	pushBlockSize := pushMetrics.GetOrCreateHistogram(fmt.Sprintf(`metrics_push_block_size_bytes{url=%q}`, pushURLRedacted))
+	pushDuration := pushMetrics.GetOrCreateHistogram(fmt.Sprintf(`metrics_push_duration_seconds{url=%q}`, pushURLRedacted), false)
+	pushBlockSize := pushMetrics.GetOrCreateHistogram(fmt.Sprintf(`metrics_push_block_size_bytes{url=%q}`, pushURLRedacted), false)
 	pushMetrics.GetOrCreateFloatCounter(fmt.Sprintf(`metrics_push_interval_seconds{url=%q}`, pushURLRedacted)).Set(interval.Seconds())
 	go func() {
 		ticker := time.NewTicker(interval)

set.go

@@ -65,8 +65,8 @@ func (s *Set) WritePrometheus(w io.Writer) {
 //   - foo{bar="baz",aaa="b"}
 //
 // The returned histogram is safe to use from concurrent goroutines.
-func (s *Set) NewHistogram(name string) *Histogram {
-	h := &Histogram{}
+func (s *Set) NewHistogram(name string, compatible bool) *Histogram {
+	h := &Histogram{compatible: compatible}
 	s.registerMetric(name, h)
 	return h
 }
@@ -84,7 +84,7 @@ func (s *Set) NewHistogram(name string) *Histogram {
 // The returned histogram is safe to use from concurrent goroutines.
 //
 // Performance tip: prefer NewHistogram instead of GetOrCreateHistogram.
-func (s *Set) GetOrCreateHistogram(name string) *Histogram {
+func (s *Set) GetOrCreateHistogram(name string, compatible bool) *Histogram {
 	s.mu.Lock()
 	nm := s.m[name]
 	s.mu.Unlock()
@@ -95,7 +95,7 @@ func (s *Set) GetOrCreateHistogram(name string) *Histogram {
 		}
 		nmNew := &namedMetric{
 			name:   name,
-			metric: &Histogram{},
+			metric: &Histogram{compatible: compatible},
 		}
 		s.mu.Lock()
 		nm = s.m[name]

set_test.go

@@ -29,7 +29,7 @@ func TestNewSet(t *testing.T) {
 			if sm == nil {
 				t.Fatalf("NewSummary returned nil")
 			}
-			h := s.NewHistogram(fmt.Sprintf("histogram_%d", j))
+			h := s.NewHistogram(fmt.Sprintf("histogram_%d", j), false)
 			if h == nil {
 				t.Fatalf("NewHistogram returned nil")
 			}
@@ -71,7 +71,7 @@ func TestSetUnregisterAllMetrics(t *testing.T) {
 		for i := 0; i < 10; i++ {
 			_ = s.NewCounter(fmt.Sprintf("counter_%d", i))
 			_ = s.NewSummary(fmt.Sprintf("summary_%d", i))
-			_ = s.NewHistogram(fmt.Sprintf("histogram_%d", i))
+			_ = s.NewHistogram(fmt.Sprintf("histogram_%d", i), false)
 			_ = s.NewGauge(fmt.Sprintf("gauge_%d", i), func() float64 { return 0 })
 			expectedMetricsCount += 4
 		}