client_golang/model/fingerprinting.go

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// Copyright 2013 Prometheus Team
// 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 model
import (
"encoding/binary"
"fmt"
"hash/fnv"
"sort"
"strconv"
)
// Fingerprint provides a hash-capable representation of a Metric.
// For our purposes, FNV-1A 64-bit is used.
type Fingerprint uint64
func (f Fingerprint) String() string {
return fmt.Sprintf("%016x", uint64(f))
}
// Less implements sort.Interface.
func (f Fingerprint) Less(o Fingerprint) bool {
return f < o
}
// Equal implements sort.Interface.
func (f Fingerprint) Equal(o Fingerprint) bool {
return f == o
}
// LoadFromString transforms a string representation into a Fingerprint.
func (f *Fingerprint) LoadFromString(s string) error {
num, err := strconv.ParseUint(s, 16, 64)
if err != nil {
return err
}
*f = Fingerprint(num)
return nil
}
// LoadFromMetric decomposes a Metric into this Fingerprint
func (f *Fingerprint) LoadFromMetric(m Metric) {
labelLength := len(m)
labelNames := make([]string, 0, labelLength)
for labelName := range m {
labelNames = append(labelNames, string(labelName))
}
sort.Strings(labelNames)
summer := fnv.New64a()
for _, labelName := range labelNames {
labelValue := m[LabelName(labelName)]
summer.Write([]byte(labelName))
summer.Write([]byte{0})
summer.Write([]byte(labelValue))
}
*f = Fingerprint(binary.LittleEndian.Uint64(summer.Sum(nil)))
}
// Fingerprints represents a collection of Fingerprint subject to a given
// natural sorting scheme. It implements sort.Interface.
type Fingerprints []Fingerprint
// Len implements sort.Interface.
func (f Fingerprints) Len() int {
return len(f)
}
// Less implements sort.Interface.
func (f Fingerprints) Less(i, j int) bool {
return f[i] < f[j]
}
// Swap implements sort.Interface.
func (f Fingerprints) Swap(i, j int) {
f[i], f[j] = f[j], f[i]
}
// FingerprintSet is a set of Fingerprints.
type FingerprintSet map[Fingerprint]struct{}
// Equal returns true if both sets contain the same elements (and not more).
func (s FingerprintSet) Equal(o FingerprintSet) bool {
if len(s) != len(o) {
return false
}
for k := range s {
if _, ok := o[k]; !ok {
return false
}
}
return true
}
// Intersection returns the elements contained in both sets.
func (s FingerprintSet) Intersection(o FingerprintSet) FingerprintSet {
myLength, otherLength := len(s), len(o)
if myLength == 0 || otherLength == 0 {
return FingerprintSet{}
}
subSet := s
superSet := o
if otherLength < myLength {
subSet = o
superSet = s
}
out := FingerprintSet{}
for k := range subSet {
if _, ok := superSet[k]; ok {
out[k] = struct{}{}
}
}
return out
}