prometheus/promql/histogram_stats_iterator.go

143 lines
4.2 KiB
Go

// 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 promql
import (
"github.com/prometheus/prometheus/model/histogram"
"github.com/prometheus/prometheus/model/value"
"github.com/prometheus/prometheus/tsdb/chunkenc"
)
type histogramStatsIterator struct {
chunkenc.Iterator
currentH *histogram.Histogram
lastH *histogram.Histogram
currentFH *histogram.FloatHistogram
lastFH *histogram.FloatHistogram
}
// NewHistogramStatsIterator creates an iterator which returns histogram objects
// which have only their sum and count values populated. The iterator handles
// counter reset detection internally and sets the counter reset hint accordingly
// in each returned histogram objects.
func NewHistogramStatsIterator(it chunkenc.Iterator) chunkenc.Iterator {
return &histogramStatsIterator{
Iterator: it,
currentH: &histogram.Histogram{},
currentFH: &histogram.FloatHistogram{},
}
}
// AtHistogram returns the next timestamp/histogram pair. The counter reset
// detection is guaranteed to be correct only when the caller does not switch
// between AtHistogram and AtFloatHistogram calls.
func (f *histogramStatsIterator) AtHistogram(h *histogram.Histogram) (int64, *histogram.Histogram) {
var t int64
t, f.currentH = f.Iterator.AtHistogram(f.currentH)
if value.IsStaleNaN(f.currentH.Sum) {
h = &histogram.Histogram{Sum: f.currentH.Sum}
return t, h
}
if h == nil {
h = &histogram.Histogram{
CounterResetHint: f.getResetHint(f.currentH),
Count: f.currentH.Count,
Sum: f.currentH.Sum,
}
f.setLastH(f.currentH)
return t, h
}
h.CounterResetHint = f.getResetHint(f.currentH)
h.Count = f.currentH.Count
h.Sum = f.currentH.Sum
f.setLastH(f.currentH)
return t, h
}
// AtFloatHistogram returns the next timestamp/float histogram pair. The counter
// reset detection is guaranteed to be correct only when the caller does not
// switch between AtHistogram and AtFloatHistogram calls.
func (f *histogramStatsIterator) AtFloatHistogram(fh *histogram.FloatHistogram) (int64, *histogram.FloatHistogram) {
var t int64
t, f.currentFH = f.Iterator.AtFloatHistogram(f.currentFH)
if value.IsStaleNaN(f.currentFH.Sum) {
return t, &histogram.FloatHistogram{Sum: f.currentFH.Sum}
}
if fh == nil {
fh = &histogram.FloatHistogram{
CounterResetHint: f.getFloatResetHint(f.currentFH.CounterResetHint),
Count: f.currentFH.Count,
Sum: f.currentFH.Sum,
}
f.setLastFH(f.currentFH)
return t, fh
}
fh.CounterResetHint = f.getFloatResetHint(f.currentFH.CounterResetHint)
fh.Count = f.currentFH.Count
fh.Sum = f.currentFH.Sum
f.setLastFH(f.currentFH)
return t, fh
}
func (f *histogramStatsIterator) setLastH(h *histogram.Histogram) {
if f.lastH == nil {
f.lastH = h.Copy()
} else {
h.CopyTo(f.lastH)
}
}
func (f *histogramStatsIterator) setLastFH(fh *histogram.FloatHistogram) {
if f.lastFH == nil {
f.lastFH = fh.Copy()
} else {
fh.CopyTo(f.lastFH)
}
}
func (f *histogramStatsIterator) getFloatResetHint(hint histogram.CounterResetHint) histogram.CounterResetHint {
if hint != histogram.UnknownCounterReset {
return hint
}
if f.lastFH == nil {
return histogram.NotCounterReset
}
if f.currentFH.DetectReset(f.lastFH) {
return histogram.CounterReset
}
return histogram.NotCounterReset
}
func (f *histogramStatsIterator) getResetHint(h *histogram.Histogram) histogram.CounterResetHint {
if h.CounterResetHint != histogram.UnknownCounterReset {
return h.CounterResetHint
}
if f.lastH == nil {
return histogram.NotCounterReset
}
fh, prevFH := h.ToFloat(nil), f.lastH.ToFloat(nil)
if fh.DetectReset(prevFH) {
return histogram.CounterReset
}
return histogram.NotCounterReset
}