/
translator.go
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/
translator.go
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// Copyright 2022 Cockroach Labs Inc.
//
// 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 translator provides the utilites to convert a HDR histogram to a log linear histogram.
package translator
import (
"context"
"io"
"math"
"regexp"
"github.com/cockroachlabs/visus/internal/store"
dto "github.com/prometheus/client_model/go"
"github.com/prometheus/common/expfmt"
log "github.com/sirupsen/logrus"
)
// Translator translate histograms to a log linear format.
type Translator interface {
// Translate histograms to a log linear format, and write the result to a writer.
Translate(ctx context.Context, family *dto.MetricFamily, out io.Writer) error
}
// Translator defines the property of a histogram filter.
type translator struct {
histogram store.Histogram
include *regexp.Regexp
}
// New instantiate a new translator from a histogram definition.
func New(h store.Histogram) (Translator, error) {
include, err := regexp.Compile(h.Regex)
if err != nil {
return nil, err
}
return &translator{
histogram: h,
include: include,
}, nil
}
func (t *translator) Translate(ctx context.Context, family *dto.MetricFamily, out io.Writer) error {
if family.GetType() == dto.MetricType_HISTOGRAM {
if t.include.MatchString(family.GetName()) {
log.Debugf("Translating %v", family.GetName())
t.translate(family)
_, err := expfmt.MetricFamilyToText(out, family)
if err != nil {
return err
}
}
}
return nil
}
// TranslateHistogram translates the HDR Histogram into a Log10 linear histogram
func (t *translator) translate(mf *dto.MetricFamily) {
histogram := t.histogram
log.Debugf("Translating %+v", histogram)
bins := histogram.Bins
for _, m := range mf.Metric {
var prev *dto.Bucket = nil
requiredBuckets := 1
max := 0.0
if len(m.Histogram.Bucket) >= 2 {
if histogram.End > 0 {
max = float64(histogram.End)
} else {
for _, b := range m.Histogram.Bucket {
u := b.GetUpperBound()
if u != math.Inf(1) && u > max {
max = u
}
}
}
requiredBuckets = requiredBuckets + int(math.Ceil(math.Log10(float64(max))))*bins
}
newBuckets := make([]*dto.Bucket, 0, requiredBuckets)
currLog10Bucket := createLog10Bucket(float64(histogram.Start), max, bins)
for _, curr := range m.GetHistogram().GetBucket() {
newBuckets = currLog10Bucket.addLog10Buckets(curr, prev, newBuckets)
prev = curr
}
m.Histogram.Bucket = newBuckets
}
}