mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-28 06:59:40 -08:00
107 lines
3.3 KiB
Go
107 lines
3.3 KiB
Go
// Copyright 2015 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 ast
|
|
|
|
import (
|
|
"math"
|
|
"sort"
|
|
|
|
clientmodel "github.com/prometheus/client_golang/model"
|
|
)
|
|
|
|
// Helpers to calculate quantiles.
|
|
|
|
// excludedLabels are the labels to exclude from signature calculation for
|
|
// quantiles.
|
|
var excludedLabels = map[clientmodel.LabelName]struct{}{
|
|
clientmodel.MetricNameLabel: {},
|
|
clientmodel.BucketLabel: {},
|
|
}
|
|
|
|
type bucket struct {
|
|
upperBound float64
|
|
count clientmodel.SampleValue
|
|
}
|
|
|
|
// buckets implements sort.Interface.
|
|
type buckets []bucket
|
|
|
|
func (b buckets) Len() int { return len(b) }
|
|
func (b buckets) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
|
|
func (b buckets) Less(i, j int) bool { return b[i].upperBound < b[j].upperBound }
|
|
|
|
type metricWithBuckets struct {
|
|
metric clientmodel.COWMetric
|
|
buckets buckets
|
|
}
|
|
|
|
// quantile calculates the quantile 'q' based on the given buckets. The buckets
|
|
// will be sorted by upperBound by this function (i.e. no sorting needed before
|
|
// calling this function). The quantile value is interpolated assuming a linear
|
|
// distribution within a bucket. However, if the quantile falls into the highest
|
|
// bucket, the upper bound of the 2nd highest bucket is returned. A natural
|
|
// lower bound of 0 is assumed if the upper bound of the lowest bucket is
|
|
// greater 0. In that case, interpolation in the lowest bucket happens linearly
|
|
// between 0 and the upper bound of the lowest bucket. However, if the lowest
|
|
// bucket has an upper bound less or equal 0, this upper bound is returned if
|
|
// the quantile falls into the lowest bucket.
|
|
//
|
|
// There are a number of special cases (once we have a way to report errors
|
|
// happening during evaluations of AST functions, we should report those
|
|
// explicitly):
|
|
//
|
|
// If 'buckets' has fewer than 2 elements, NaN is returned.
|
|
//
|
|
// If the highest bucket is not +Inf, NaN is returned.
|
|
//
|
|
// If q<0, -Inf is returned.
|
|
//
|
|
// If q>1, +Inf is returned.
|
|
func quantile(q clientmodel.SampleValue, buckets buckets) float64 {
|
|
if q < 0 {
|
|
return math.Inf(-1)
|
|
}
|
|
if q > 1 {
|
|
return math.Inf(+1)
|
|
}
|
|
if len(buckets) < 2 {
|
|
return math.NaN()
|
|
}
|
|
sort.Sort(buckets)
|
|
if !math.IsInf(buckets[len(buckets)-1].upperBound, +1) {
|
|
return math.NaN()
|
|
}
|
|
|
|
rank := q * buckets[len(buckets)-1].count
|
|
b := sort.Search(len(buckets)-1, func(i int) bool { return buckets[i].count >= rank })
|
|
|
|
if b == len(buckets)-1 {
|
|
return buckets[len(buckets)-2].upperBound
|
|
}
|
|
if b == 0 && buckets[0].upperBound <= 0 {
|
|
return buckets[0].upperBound
|
|
}
|
|
var (
|
|
bucketStart float64
|
|
bucketEnd = buckets[b].upperBound
|
|
count = buckets[b].count
|
|
)
|
|
if b > 0 {
|
|
bucketStart = buckets[b-1].upperBound
|
|
count -= buckets[b-1].count
|
|
rank -= buckets[b-1].count
|
|
}
|
|
return bucketStart + (bucketEnd-bucketStart)*float64(rank/count)
|
|
}
|