Merge pull request #15220 from prometheus/nhcb-scrape-optimize

perf(nhcb): scrape optimize

model/textparse/nhcbparse.go

@@ -283,18 +283,18 @@ func (p *NHCBParser) handleClassicHistogramSeries(lset labels.Labels) bool {
 		le, err := strconv.ParseFloat(lset.Get(labels.BucketLabel), 64)
 		if err == nil && !math.IsNaN(le) {
 			p.processClassicHistogramSeries(lset, "_bucket", func(hist *convertnhcb.TempHistogram) {
-				hist.BucketCounts[le] = p.value
+				_ = hist.SetBucketCount(le, p.value)
 			})
 			return true
 		}
 	case strings.HasSuffix(mName, "_count"):
 		p.processClassicHistogramSeries(lset, "_count", func(hist *convertnhcb.TempHistogram) {
-			hist.Count = p.value
+			_ = hist.SetCount(p.value)
 		})
 		return true
 	case strings.HasSuffix(mName, "_sum"):
 		p.processClassicHistogramSeries(lset, "_sum", func(hist *convertnhcb.TempHistogram) {
-			hist.Sum = p.value
+			_ = hist.SetSum(p.value)
 		})
 		return true
 	}
@@ -306,8 +306,8 @@ func (p *NHCBParser) processClassicHistogramSeries(lset labels.Labels, suffix st
 		p.storeClassicLabels()
 		p.tempCT = p.parser.CreatedTimestamp()
 		p.state = stateCollecting
+		p.tempLsetNHCB = convertnhcb.GetHistogramMetricBase(lset, suffix)
 	}
-	p.tempLsetNHCB = convertnhcb.GetHistogramMetricBase(lset, suffix)
 	p.storeExemplars()
 	updateHist(&p.tempNHCB)
 }
@@ -335,7 +335,6 @@ func (p *NHCBParser) nextExemplarPtr() *exemplar.Exemplar {
 func (p *NHCBParser) swapExemplars() {
 	p.exemplars = p.tempExemplars[:p.tempExemplarCount]
 	p.tempExemplars = p.tempExemplars[:0]
-	p.tempExemplarCount = 0
 }
 
 // processNHCB converts the collated classic histogram series to NHCB and caches the info
@@ -344,33 +343,32 @@ func (p *NHCBParser) processNHCB() bool {
 	if p.state != stateCollecting {
 		return false
 	}
-	ub := make([]float64, 0, len(p.tempNHCB.BucketCounts))
-	for b := range p.tempNHCB.BucketCounts {
-		ub = append(ub, b)
-	}
-	upperBounds, hBase := convertnhcb.ProcessUpperBoundsAndCreateBaseHistogram(ub, false)
-	fhBase := hBase.ToFloat(nil)
-	h, fh := convertnhcb.NewHistogram(p.tempNHCB, upperBounds, hBase, fhBase)
-	if h != nil {
-		if err := h.Validate(); err != nil {
-			return false
+	h, fh, err := p.tempNHCB.Convert()
+	if err == nil {
+		if h != nil {
+			if err := h.Validate(); err != nil {
+				return false
+			}
+			p.hNHCB = h
+			p.fhNHCB = nil
+		} else if fh != nil {
+			if err := fh.Validate(); err != nil {
+				return false
+			}
+			p.hNHCB = nil
+			p.fhNHCB = fh
 		}
-		p.hNHCB = h
-		p.fhNHCB = nil
-	} else if fh != nil {
-		if err := fh.Validate(); err != nil {
-			return false
-		}
-		p.hNHCB = nil
-		p.fhNHCB = fh
+		p.metricStringNHCB = p.tempLsetNHCB.Get(labels.MetricName) + strings.ReplaceAll(p.tempLsetNHCB.DropMetricName().String(), ", ", ",")
+		p.bytesNHCB = []byte(p.metricStringNHCB)
+		p.lsetNHCB = p.tempLsetNHCB
+		p.swapExemplars()
+		p.ctNHCB = p.tempCT
+		p.state = stateEmitting
+	} else {
+		p.state = stateStart
 	}
-	p.metricStringNHCB = p.tempLsetNHCB.Get(labels.MetricName) + strings.ReplaceAll(p.tempLsetNHCB.DropMetricName().String(), ", ", ",")
-	p.bytesNHCB = []byte(p.metricStringNHCB)
-	p.lsetNHCB = p.tempLsetNHCB
-	p.swapExemplars()
-	p.ctNHCB = p.tempCT
-	p.tempNHCB = convertnhcb.NewTempHistogram()
-	p.state = stateEmitting
+	p.tempNHCB.Reset()
+	p.tempExemplarCount = 0
 	p.tempCT = nil
-	return true
+	return err == nil
 }

model/textparse/nhcbparse_test.go

@@ -500,8 +500,8 @@ something_bucket{a="b",le="+Inf"} 9 # {id="something-test"} 2e100 123.000
 				Schema:          histogram.CustomBucketsSchema,
 				Count:           9,
 				Sum:             42123.0,
-				PositiveSpans:   []histogram.Span{{Offset: 0, Length: 1}, {Offset: 1, Length: 1}},
-				PositiveBuckets: []int64{8, -7},
+				PositiveSpans:   []histogram.Span{{Offset: 0, Length: 3}},
+				PositiveBuckets: []int64{8, -8, 1},
 				CustomValues:    []float64{0.0, 1.0}, // We do not store the +Inf boundary.
 			},
 			lset: labels.FromStrings("__name__", "something", "a", "b"),
@@ -937,3 +937,48 @@ test_histogram1_bucket{le="-0.0003899999999999998"} 4 1234568
 test_histogram1_bucket{le="-0.0002899999999999998"} 16 1234568
 test_histogram1_bucket{le="+Inf"} 175 1234568`
 }
+
+func TestNHCBParserErrorHandling(t *testing.T) {
+	input := `# HELP something Histogram with non cumulative buckets
+# TYPE something histogram
+something_count 18
+something_sum 324789.4
+something_created 1520430001
+something_bucket{le="0.0"} 18
+something_bucket{le="+Inf"} 1
+something_count{a="b"} 9
+something_sum{a="b"} 42123
+something_created{a="b"} 1520430002
+something_bucket{a="b",le="0.0"} 1
+something_bucket{a="b",le="+Inf"} 9
+# EOF`
+	exp := []parsedEntry{
+		{
+			m:    "something",
+			help: "Histogram with non cumulative buckets",
+		},
+		{
+			m:   "something",
+			typ: model.MetricTypeHistogram,
+		},
+		// The parser should skip the series with non-cumulative buckets.
+		{
+			m: `something{a="b"}`,
+			shs: &histogram.Histogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Count:           9,
+				Sum:             42123.0,
+				PositiveSpans:   []histogram.Span{{Offset: 0, Length: 2}},
+				PositiveBuckets: []int64{1, 7},
+				CustomValues:    []float64{0.0}, // We do not store the +Inf boundary.
+			},
+			lset: labels.FromStrings("__name__", "something", "a", "b"),
+			ct:   int64p(1520430002000),
+		},
+	}
+
+	p := NewOpenMetricsParser([]byte(input), labels.NewSymbolTable(), WithOMParserCTSeriesSkipped())
+	p = NewNHCBParser(p, labels.NewSymbolTable(), false)
+	got := testParse(t, p)
+	requireEntries(t, exp, got)
+}

promql/promqltest/test.go

@@ -482,18 +482,16 @@ func (cmd *loadCmd) append(a storage.Appender) error {
 
 type tempHistogramWrapper struct {
 	metric        labels.Labels
-	upperBounds   []float64
 	histogramByTs map[int64]convertnhcb.TempHistogram
 }
 
 func newTempHistogramWrapper() tempHistogramWrapper {
 	return tempHistogramWrapper{
-		upperBounds:   []float64{},
 		histogramByTs: map[int64]convertnhcb.TempHistogram{},
 	}
 }
 
-func processClassicHistogramSeries(m labels.Labels, suffix string, histogramMap map[uint64]tempHistogramWrapper, smpls []promql.Sample, updateHistogramWrapper func(*tempHistogramWrapper), updateHistogram func(*convertnhcb.TempHistogram, float64)) {
+func processClassicHistogramSeries(m labels.Labels, suffix string, histogramMap map[uint64]tempHistogramWrapper, smpls []promql.Sample, updateHistogram func(*convertnhcb.TempHistogram, float64)) {
 	m2 := convertnhcb.GetHistogramMetricBase(m, suffix)
 	m2hash := m2.Hash()
 	histogramWrapper, exists := histogramMap[m2hash]
@@ -501,9 +499,6 @@ func processClassicHistogramSeries(m labels.Labels, suffix string, histogramMap
 		histogramWrapper = newTempHistogramWrapper()
 	}
 	histogramWrapper.metric = m2
-	if updateHistogramWrapper != nil {
-		updateHistogramWrapper(&histogramWrapper)
-	}
 	for _, s := range smpls {
 		if s.H != nil {
 			continue
@@ -534,18 +529,16 @@ func (cmd *loadCmd) appendCustomHistogram(a storage.Appender) error {
 			if err != nil || math.IsNaN(le) {
 				continue
 			}
-			processClassicHistogramSeries(m, "_bucket", histogramMap, smpls, func(histogramWrapper *tempHistogramWrapper) {
-				histogramWrapper.upperBounds = append(histogramWrapper.upperBounds, le)
-			}, func(histogram *convertnhcb.TempHistogram, f float64) {
-				histogram.BucketCounts[le] = f
+			processClassicHistogramSeries(m, "_bucket", histogramMap, smpls, func(histogram *convertnhcb.TempHistogram, f float64) {
+				_ = histogram.SetBucketCount(le, f)
 			})
 		case strings.HasSuffix(mName, "_count"):
-			processClassicHistogramSeries(m, "_count", histogramMap, smpls, nil, func(histogram *convertnhcb.TempHistogram, f float64) {
-				histogram.Count = f
+			processClassicHistogramSeries(m, "_count", histogramMap, smpls, func(histogram *convertnhcb.TempHistogram, f float64) {
+				_ = histogram.SetCount(f)
 			})
 		case strings.HasSuffix(mName, "_sum"):
-			processClassicHistogramSeries(m, "_sum", histogramMap, smpls, nil, func(histogram *convertnhcb.TempHistogram, f float64) {
-				histogram.Sum = f
+			processClassicHistogramSeries(m, "_sum", histogramMap, smpls, func(histogram *convertnhcb.TempHistogram, f float64) {
+				_ = histogram.SetSum(f)
 			})
 		}
 	}
@@ -553,11 +546,12 @@ func (cmd *loadCmd) appendCustomHistogram(a storage.Appender) error {
 	// Convert the collated classic histogram data into native histograms
 	// with custom bounds and append them to the storage.
 	for _, histogramWrapper := range histogramMap {
-		upperBounds, hBase := convertnhcb.ProcessUpperBoundsAndCreateBaseHistogram(histogramWrapper.upperBounds, true)
-		fhBase := hBase.ToFloat(nil)
 		samples := make([]promql.Sample, 0, len(histogramWrapper.histogramByTs))
 		for t, histogram := range histogramWrapper.histogramByTs {
-			h, fh := convertnhcb.NewHistogram(histogram, upperBounds, hBase, fhBase)
+			h, fh, err := histogram.Convert()
+			if err != nil {
+				return err
+			}
 			if fh == nil {
 				if err := h.Validate(); err != nil {
 					return err

util/convertnhcb/convertnhcb.go

@@ -14,6 +14,7 @@
 package convertnhcb
 
 import (
+	"errors"
 	"fmt"
 	"math"
 	"sort"
@@ -23,129 +24,212 @@ import (
 	"github.com/prometheus/prometheus/model/labels"
 )
 
+var (
+	errNegativeBucketCount = errors.New("bucket count must be non-negative")
+	errNegativeCount       = errors.New("count must be non-negative")
+	errCountMismatch       = errors.New("count mismatch")
+	errCountNotCumulative  = errors.New("count is not cumulative")
+)
+
+type tempHistogramBucket struct {
+	le    float64
+	count float64
+}
+
 // TempHistogram is used to collect information about classic histogram
 // samples incrementally before creating a histogram.Histogram or
 // histogram.FloatHistogram based on the values collected.
 type TempHistogram struct {
-	BucketCounts map[float64]float64
-	Count        float64
-	Sum          float64
-	HasFloat     bool
+	buckets  []tempHistogramBucket
+	count    float64
+	sum      float64
+	err      error
+	hasCount bool
 }
 
 // NewTempHistogram creates a new TempHistogram to
 // collect information about classic histogram samples.
 func NewTempHistogram() TempHistogram {
 	return TempHistogram{
-		BucketCounts: map[float64]float64{},
+		buckets: make([]tempHistogramBucket, 0, 10),
 	}
 }
 
-func (h TempHistogram) getIntBucketCounts() (map[float64]int64, error) {
-	bucketCounts := map[float64]int64{}
-	for le, count := range h.BucketCounts {
-		intCount := int64(math.Round(count))
-		if float64(intCount) != count {
-			return nil, fmt.Errorf("bucket count %f for le %g is not an integer", count, le)
+func (h TempHistogram) Err() error {
+	return h.err
+}
+
+func (h *TempHistogram) Reset() {
+	h.buckets = h.buckets[:0]
+	h.count = 0
+	h.sum = 0
+	h.err = nil
+	h.hasCount = false
+}
+
+func (h *TempHistogram) SetBucketCount(boundary, count float64) error {
+	if h.err != nil {
+		return h.err
+	}
+	if count < 0 {
+		h.err = fmt.Errorf("%w: le=%g, count=%g", errNegativeBucketCount, boundary, count)
+		return h.err
+	}
+	// Assume that the elements are added in order.
+	switch {
+	case len(h.buckets) == 0:
+		h.buckets = append(h.buckets, tempHistogramBucket{le: boundary, count: count})
+	case h.buckets[len(h.buckets)-1].le < boundary:
+		// Happy case is "<".
+		if count < h.buckets[len(h.buckets)-1].count {
+			h.err = fmt.Errorf("%w: %g < %g", errCountNotCumulative, count, h.buckets[len(h.buckets)-1].count)
+			return h.err
 		}
-		bucketCounts[le] = intCount
-	}
-	return bucketCounts, nil
-}
-
-// ProcessUpperBoundsAndCreateBaseHistogram prepares an integer native
-// histogram with custom buckets based on the provided upper bounds.
-// Everything is set except the bucket counts.
-// The sorted upper bounds are also returned.
-func ProcessUpperBoundsAndCreateBaseHistogram(upperBounds0 []float64, needsDedup bool) ([]float64, *histogram.Histogram) {
-	sort.Float64s(upperBounds0)
-	var upperBounds []float64
-	if needsDedup {
-		upperBounds = make([]float64, 0, len(upperBounds0))
-		prevLE := math.Inf(-1)
-		for _, le := range upperBounds0 {
-			if le != prevLE {
-				upperBounds = append(upperBounds, le)
-				prevLE = le
-			}
+		h.buckets = append(h.buckets, tempHistogramBucket{le: boundary, count: count})
+	case h.buckets[len(h.buckets)-1].le == boundary:
+		// Ignore this, as it is a duplicate sample.
+	default:
+		// Find the correct position to insert.
+		i := sort.Search(len(h.buckets), func(i int) bool {
+			return h.buckets[i].le >= boundary
+		})
+		if h.buckets[i].le == boundary {
+			// Ignore this, as it is a duplicate sample.
+			return nil
 		}
-	} else {
-		upperBounds = upperBounds0
-	}
-	var customBounds []float64
-	if upperBounds[len(upperBounds)-1] == math.Inf(1) {
-		customBounds = upperBounds[:len(upperBounds)-1]
-	} else {
-		customBounds = upperBounds
-	}
-	return upperBounds, &histogram.Histogram{
-		Count:  0,
-		Sum:    0,
-		Schema: histogram.CustomBucketsSchema,
-		PositiveSpans: []histogram.Span{
-			{Offset: 0, Length: uint32(len(upperBounds))},
-		},
-		PositiveBuckets: make([]int64, len(upperBounds)),
-		CustomValues:    customBounds,
-	}
-}
-
-// NewHistogram fills the bucket counts in the provided histogram.Histogram
-// or histogram.FloatHistogram based on the provided temporary histogram and
-// upper bounds.
-func NewHistogram(histogram TempHistogram, upperBounds []float64, hBase *histogram.Histogram, fhBase *histogram.FloatHistogram) (*histogram.Histogram, *histogram.FloatHistogram) {
-	intBucketCounts, err := histogram.getIntBucketCounts()
-	if err != nil {
-		return nil, newFloatHistogram(histogram, upperBounds, histogram.BucketCounts, fhBase)
-	}
-	return newIntegerHistogram(histogram, upperBounds, intBucketCounts, hBase), nil
-}
-
-func newIntegerHistogram(histogram TempHistogram, upperBounds []float64, bucketCounts map[float64]int64, hBase *histogram.Histogram) *histogram.Histogram {
-	h := hBase.Copy()
-	absBucketCounts := make([]int64, len(h.PositiveBuckets))
-	var prevCount, total int64
-	for i, le := range upperBounds {
-		currCount, exists := bucketCounts[le]
-		if !exists {
-			currCount = 0
+		if i > 0 && count < h.buckets[i-1].count {
+			h.err = fmt.Errorf("%w: %g < %g", errCountNotCumulative, count, h.buckets[i-1].count)
+			return h.err
 		}
-		count := currCount - prevCount
-		absBucketCounts[i] = count
-		total += count
-		prevCount = currCount
+		if count > h.buckets[i].count {
+			h.err = fmt.Errorf("%w: %g > %g", errCountNotCumulative, count, h.buckets[i].count)
+			return h.err
+		}
+		// Insert at the correct position unless duplicate.
+		h.buckets = append(h.buckets, tempHistogramBucket{})
+		copy(h.buckets[i+1:], h.buckets[i:])
+		h.buckets[i] = tempHistogramBucket{le: boundary, count: count}
 	}
-	h.PositiveBuckets[0] = absBucketCounts[0]
-	for i := 1; i < len(h.PositiveBuckets); i++ {
-		h.PositiveBuckets[i] = absBucketCounts[i] - absBucketCounts[i-1]
-	}
-	h.Sum = histogram.Sum
-	if histogram.Count != 0 {
-		total = int64(histogram.Count)
-	}
-	h.Count = uint64(total)
-	return h.Compact(0)
+	return nil
 }
 
-func newFloatHistogram(histogram TempHistogram, upperBounds []float64, bucketCounts map[float64]float64, fhBase *histogram.FloatHistogram) *histogram.FloatHistogram {
-	fh := fhBase.Copy()
-	var prevCount, total float64
-	for i, le := range upperBounds {
-		currCount, exists := bucketCounts[le]
-		if !exists {
-			currCount = 0
+func (h *TempHistogram) SetCount(count float64) error {
+	if h.err != nil {
+		return h.err
+	}
+	if count < 0 {
+		h.err = fmt.Errorf("%w: count=%g", errNegativeCount, count)
+		return h.err
+	}
+	h.count = count
+	h.hasCount = true
+	return nil
+}
+
+func (h *TempHistogram) SetSum(sum float64) error {
+	if h.err != nil {
+		return h.err
+	}
+	h.sum = sum
+	return nil
+}
+
+func (h TempHistogram) Convert() (*histogram.Histogram, *histogram.FloatHistogram, error) {
+	if h.err != nil {
+		return nil, nil, h.err
+	}
+
+	if len(h.buckets) == 0 || h.buckets[len(h.buckets)-1].le != math.Inf(1) {
+		// No +Inf bucket.
+		if !h.hasCount && len(h.buckets) > 0 {
+			// No count either, so set count to the last known bucket's count.
+			h.count = h.buckets[len(h.buckets)-1].count
 		}
-		count := currCount - prevCount
-		fh.PositiveBuckets[i] = count
-		total += count
-		prevCount = currCount
+		// Let the last bucket be +Inf with the overall count.
+		h.buckets = append(h.buckets, tempHistogramBucket{le: math.Inf(1), count: h.count})
 	}
-	fh.Sum = histogram.Sum
-	if histogram.Count != 0 {
-		total = histogram.Count
+
+	if !h.hasCount {
+		h.count = h.buckets[len(h.buckets)-1].count
+		h.hasCount = true
 	}
-	fh.Count = total
-	return fh.Compact(0)
+
+	for _, b := range h.buckets {
+		intCount := int64(math.Round(b.count))
+		if b.count != float64(intCount) {
+			return h.convertToFloatHistogram()
+		}
+	}
+
+	intCount := uint64(math.Round(h.count))
+	if h.count != float64(intCount) {
+		return h.convertToFloatHistogram()
+	}
+	return h.convertToIntegerHistogram(intCount)
+}
+
+func (h TempHistogram) convertToIntegerHistogram(count uint64) (*histogram.Histogram, *histogram.FloatHistogram, error) {
+	rh := &histogram.Histogram{
+		Schema:          histogram.CustomBucketsSchema,
+		Count:           count,
+		Sum:             h.sum,
+		PositiveSpans:   []histogram.Span{{Length: uint32(len(h.buckets))}},
+		PositiveBuckets: make([]int64, len(h.buckets)),
+	}
+
+	if len(h.buckets) > 1 {
+		rh.CustomValues = make([]float64, len(h.buckets)-1) // Not storing the last +Inf bucket.
+	}
+
+	prevCount := int64(0)
+	prevDelta := int64(0)
+	for i, b := range h.buckets {
+		// delta is the actual bucket count as the input is cumulative.
+		delta := int64(b.count) - prevCount
+		rh.PositiveBuckets[i] = delta - prevDelta
+		prevCount = int64(b.count)
+		prevDelta = delta
+		if b.le != math.Inf(1) {
+			rh.CustomValues[i] = b.le
+		}
+	}
+
+	if count != uint64(h.buckets[len(h.buckets)-1].count) {
+		h.err = fmt.Errorf("%w: count=%d != le=%g count=%g", errCountMismatch, count, h.buckets[len(h.buckets)-1].le, h.buckets[len(h.buckets)-1].count)
+		return nil, nil, h.err
+	}
+
+	return rh.Compact(2), nil, nil
+}
+
+func (h TempHistogram) convertToFloatHistogram() (*histogram.Histogram, *histogram.FloatHistogram, error) {
+	rh := &histogram.FloatHistogram{
+		Schema:          histogram.CustomBucketsSchema,
+		Count:           h.count,
+		Sum:             h.sum,
+		PositiveSpans:   []histogram.Span{{Length: uint32(len(h.buckets))}},
+		PositiveBuckets: make([]float64, len(h.buckets)),
+	}
+
+	if len(h.buckets) > 1 {
+		rh.CustomValues = make([]float64, len(h.buckets)-1) // Not storing the last +Inf bucket.
+	}
+
+	prevCount := 0.0
+	for i, b := range h.buckets {
+		rh.PositiveBuckets[i] = b.count - prevCount
+		prevCount = b.count
+		if b.le != math.Inf(1) {
+			rh.CustomValues[i] = b.le
+		}
+	}
+
+	if h.count != h.buckets[len(h.buckets)-1].count {
+		h.err = fmt.Errorf("%w: count=%g != le=%g count=%g", errCountMismatch, h.count, h.buckets[len(h.buckets)-1].le, h.buckets[len(h.buckets)-1].count)
+		return nil, nil, h.err
+	}
+
+	return nil, rh.Compact(0), nil
 }
 
 func GetHistogramMetricBase(m labels.Labels, suffix string) labels.Labels {

util/convertnhcb/convertnhcb_test.go

@@ -0,0 +1,189 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package convertnhcb
+
+import (
+	"math"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/prometheus/prometheus/model/histogram"
+)
+
+func TestNHCBConvert(t *testing.T) {
+	tests := map[string]struct {
+		setup       func() *TempHistogram
+		expectedErr error
+		expectedH   *histogram.Histogram
+		expectedFH  *histogram.FloatHistogram
+	}{
+		"empty": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				return &h
+			},
+			expectedH: &histogram.Histogram{
+				Schema:          histogram.CustomBucketsSchema,
+				PositiveSpans:   []histogram.Span{},
+				PositiveBuckets: []int64{},
+			},
+		},
+		"sum only": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetSum(1000.25)
+				return &h
+			},
+			expectedH: &histogram.Histogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Sum:             1000.25,
+				PositiveSpans:   []histogram.Span{},
+				PositiveBuckets: []int64{},
+			},
+		},
+		"single integer bucket": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetSum(1000.25)
+				h.SetBucketCount(0.5, 1000)
+				return &h
+			},
+			expectedH: &histogram.Histogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Count:           1000,
+				Sum:             1000.25,
+				PositiveSpans:   []histogram.Span{{Length: 1}},
+				PositiveBuckets: []int64{1000},
+				CustomValues:    []float64{0.5},
+			},
+		},
+		"single float bucket": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetSum(1000.25)
+				h.SetBucketCount(0.5, 1337.42)
+				return &h
+			},
+			expectedFH: &histogram.FloatHistogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Count:           1337.42,
+				Sum:             1000.25,
+				PositiveSpans:   []histogram.Span{{Length: 1}},
+				PositiveBuckets: []float64{1337.42},
+				CustomValues:    []float64{0.5},
+			},
+		},
+		"happy case integer bucket": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetCount(1000)
+				h.SetSum(1000.25)
+				h.SetBucketCount(0.5, 50)
+				h.SetBucketCount(1.0, 950)
+				h.SetBucketCount(math.Inf(1), 1000)
+				return &h
+			},
+			expectedH: &histogram.Histogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Count:           1000,
+				Sum:             1000.25,
+				PositiveSpans:   []histogram.Span{{Length: 3}},
+				PositiveBuckets: []int64{50, 850, -850},
+				CustomValues:    []float64{0.5, 1.0},
+			},
+		},
+		"happy case float bucket": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetCount(1000)
+				h.SetSum(1000.25)
+				h.SetBucketCount(0.5, 50)
+				h.SetBucketCount(1.0, 950.5)
+				h.SetBucketCount(math.Inf(1), 1000)
+				return &h
+			},
+			expectedFH: &histogram.FloatHistogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Count:           1000,
+				Sum:             1000.25,
+				PositiveSpans:   []histogram.Span{{Length: 3}},
+				PositiveBuckets: []float64{50, 900.5, 49.5},
+				CustomValues:    []float64{0.5, 1.0},
+			},
+		},
+		"non cumulative bucket": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetCount(1000)
+				h.SetSum(1000.25)
+				h.SetBucketCount(0.5, 50)
+				h.SetBucketCount(1.0, 950)
+				h.SetBucketCount(math.Inf(1), 900)
+				return &h
+			},
+			expectedErr: errCountNotCumulative,
+		},
+		"negative count": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetCount(-1000)
+				h.SetSum(1000.25)
+				h.SetBucketCount(0.5, 50)
+				h.SetBucketCount(1.0, 950)
+				h.SetBucketCount(math.Inf(1), 900)
+				return &h
+			},
+			expectedErr: errNegativeCount,
+		},
+		"mixed order": {
+			setup: func() *TempHistogram {
+				h := NewTempHistogram()
+				h.SetBucketCount(0.5, 50)
+				h.SetBucketCount(math.Inf(1), 1000)
+				h.SetBucketCount(1.0, 950)
+				h.SetCount(1000)
+				h.SetSum(1000.25)
+				return &h
+			},
+			expectedH: &histogram.Histogram{
+				Schema:          histogram.CustomBucketsSchema,
+				Count:           1000,
+				Sum:             1000.25,
+				PositiveSpans:   []histogram.Span{{Length: 3}},
+				PositiveBuckets: []int64{50, 850, -850},
+				CustomValues:    []float64{0.5, 1.0},
+			},
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			th := test.setup()
+			h, fh, err := th.Convert()
+			if test.expectedErr != nil {
+				require.ErrorIs(t, err, test.expectedErr)
+				return
+			}
+			require.Equal(t, test.expectedH, h)
+			if h != nil {
+				require.NoError(t, h.Validate())
+			}
+			require.Equal(t, test.expectedFH, fh)
+			if fh != nil {
+				require.NoError(t, fh.Validate())
+			}
+		})
+	}
+}