inspektor-gadget

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// Copyright 2023 The Inspektor Gadget authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//     http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package prometheus
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import (
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	"math"
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	"strings"
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	"github.com/shopspring/decimal"
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	log "github.com/sirupsen/logrus"
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	"github.com/inspektor-gadget/inspektor-gadget/pkg/prometheus/config"
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)
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type BucketType string
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const (
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	BucketTypeExp2   BucketType = "exp2"
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	BucketTypeLinear BucketType = "linear"
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)
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var AllBucketTypes = map[string]struct{}{
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	string(BucketTypeExp2):   {},
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	string(BucketTypeLinear): {},
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}
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type BucketConfig struct {
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	Type       BucketType
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	Min        int
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	Max        int
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	Multiplier float64
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}
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func bucketConfigsFromConfig(c *config.Config) map[string]*BucketConfig {
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	buckets := make(map[string]*BucketConfig)
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	for _, m := range c.Metrics {
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		if strings.ToLower(m.Type) == "histogram" {
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			buckets[m.Name] = &BucketConfig{
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				Type:       BucketType(m.Bucket.Type),
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				Min:        m.Bucket.Min,
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				Max:        m.Bucket.Max,
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				Multiplier: m.Bucket.Multiplier,
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			}
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		}
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	}
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	return buckets
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}
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func (c *BucketConfig) buckets() []float64 {
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	switch c.Type {
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	case BucketTypeExp2:
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		return exp2Buckets(c.Min, c.Max, c.Multiplier)
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	case BucketTypeLinear:
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		return linearBuckets(c.Min, c.Max, c.Multiplier)
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	default:
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		log.Warnf("unknown bucket type: %s", c.Type)
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		return nil
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	}
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}
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func exp2Buckets(min, max int, multiplier float64) []float64 {
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	buckets := make([]float64, 0, max-min)
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	for i := min; i < max; i++ {
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		buckets = append(buckets, math.Pow(2, float64(i))*multiplier)
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	}
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	return buckets
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}
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func linearBuckets(min, max int, multiplier float64) []float64 {
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	buckets := make([]float64, 0, max-min)
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	for i := min; i < max; i++ {
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		bucketId := decimal.NewFromInt(int64(i))
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		bucketValue, _ := bucketId.Mul(decimal.NewFromFloat(multiplier)).Float64()
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		buckets = append(buckets, bucketValue)
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	}
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	return buckets
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}
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