prometheus/tsdb/tsdbutil/histogram.go
Filip Petkovski 1f69dcfa6b
Fix reusing float histograms
In https://github.com/prometheus/prometheus/pull/13276 we started reusing float histogram objects to reduce allocations in PromQL.
That PR introduces a bug where histogram pointers gets copied to the beginning of the histograms slice,
but are still kept in the end of the slice. When a new histogram is read into the last element,
it can overwrite a previous element because the pointer is the same.

This commit fixes the issue by moving outdated points to the end of the slice
so that we don't end up with duplicate pointers in the same buffer. In other words,
the slice gets rotated so that old objects can get reused.

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>
2023-12-14 11:53:58 +01:00

141 lines
3.9 KiB
Go

// Copyright 2023 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 tsdbutil
import (
"math"
"github.com/prometheus/prometheus/model/histogram"
)
func GenerateTestHistograms(n int) (r []*histogram.Histogram) {
for i := 0; i < n; i++ {
h := GenerateTestHistogram(i)
if i > 0 {
h.CounterResetHint = histogram.NotCounterReset
}
r = append(r, h)
}
return r
}
func GenerateTestHistogramsWithUnknownResetHint(n int) []*histogram.Histogram {
hs := GenerateTestHistograms(n)
for i := range hs {
hs[i].CounterResetHint = histogram.UnknownCounterReset
}
return hs
}
// GenerateTestHistogram but it is up to the user to set any known counter reset hint.
func GenerateTestHistogram(i int) *histogram.Histogram {
return &histogram.Histogram{
Count: 12 + uint64(i*9),
ZeroCount: 2 + uint64(i),
ZeroThreshold: 0.001,
Sum: 18.4 * float64(i+1),
Schema: 1,
PositiveSpans: []histogram.Span{
{Offset: 0, Length: 2},
{Offset: 1, Length: 2},
},
PositiveBuckets: []int64{int64(i + 1), 1, -1, 0},
NegativeSpans: []histogram.Span{
{Offset: 0, Length: 2},
{Offset: 1, Length: 2},
},
NegativeBuckets: []int64{int64(i + 1), 1, -1, 0},
}
}
func GenerateTestGaugeHistograms(n int) (r []*histogram.Histogram) {
for x := 0; x < n; x++ {
i := int(math.Sin(float64(x))*100) + 100
r = append(r, GenerateTestGaugeHistogram(i))
}
return r
}
func GenerateTestGaugeHistogram(i int) *histogram.Histogram {
h := GenerateTestHistogram(i)
h.CounterResetHint = histogram.GaugeType
return h
}
func GenerateTestFloatHistograms(n int) (r []*histogram.FloatHistogram) {
for i := 0; i < n; i++ {
h := GenerateTestFloatHistogram(i)
if i > 0 {
h.CounterResetHint = histogram.NotCounterReset
}
r = append(r, h)
}
return r
}
// GenerateTestFloatHistogram but it is up to the user to set any known counter reset hint.
func GenerateTestFloatHistogram(i int) *histogram.FloatHistogram {
return &histogram.FloatHistogram{
Count: 12 + float64(i*9),
ZeroCount: 2 + float64(i),
ZeroThreshold: 0.001,
Sum: 18.4 * float64(i+1),
Schema: 1,
PositiveSpans: []histogram.Span{
{Offset: 0, Length: 2},
{Offset: 1, Length: 2},
},
PositiveBuckets: []float64{float64(i + 1), float64(i + 2), float64(i + 1), float64(i + 1)},
NegativeSpans: []histogram.Span{
{Offset: 0, Length: 2},
{Offset: 1, Length: 2},
},
NegativeBuckets: []float64{float64(i + 1), float64(i + 2), float64(i + 1), float64(i + 1)},
}
}
func GenerateTestGaugeFloatHistograms(n int) (r []*histogram.FloatHistogram) {
for x := 0; x < n; x++ {
i := int(math.Sin(float64(x))*100) + 100
r = append(r, GenerateTestGaugeFloatHistogram(i))
}
return r
}
func GenerateTestGaugeFloatHistogram(i int) *histogram.FloatHistogram {
h := GenerateTestFloatHistogram(i)
h.CounterResetHint = histogram.GaugeType
return h
}
func SetHistogramNotCounterReset(h *histogram.Histogram) *histogram.Histogram {
h.CounterResetHint = histogram.NotCounterReset
return h
}
func SetHistogramCounterReset(h *histogram.Histogram) *histogram.Histogram {
h.CounterResetHint = histogram.CounterReset
return h
}
func SetFloatHistogramNotCounterReset(h *histogram.FloatHistogram) *histogram.FloatHistogram {
h.CounterResetHint = histogram.NotCounterReset
return h
}
func SetFloatHistogramCounterReset(h *histogram.FloatHistogram) *histogram.FloatHistogram {
h.CounterResetHint = histogram.CounterReset
return h
}