forked from mirror/client_golang
98 lines
2.2 KiB
Go
98 lines
2.2 KiB
Go
// Copyright 2014 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 (
|
|
"bytes"
|
|
"hash"
|
|
"hash/fnv"
|
|
)
|
|
|
|
// SeparatorByte is a byte that cannot occur in valid UTF-8 sequences and is
|
|
// used to separate label names, label values, and other strings from each other
|
|
// when calculating their combined hash value (aka signature aka fingerprint).
|
|
const SeparatorByte byte = 255
|
|
|
|
var (
|
|
// cache the signature of an empty label set.
|
|
emptyLabelSignature = fnv.New64a().Sum64()
|
|
|
|
hashAndBufPool = make(chan *hashAndBuf, 1024)
|
|
)
|
|
|
|
type hashAndBuf struct {
|
|
h hash.Hash64
|
|
b bytes.Buffer
|
|
}
|
|
|
|
func getHashAndBuf() *hashAndBuf {
|
|
select {
|
|
case hb := <-hashAndBufPool:
|
|
return hb
|
|
default:
|
|
return &hashAndBuf{h: fnv.New64a()}
|
|
}
|
|
}
|
|
|
|
func putHashAndBuf(hb *hashAndBuf) {
|
|
select {
|
|
case hashAndBufPool <- hb:
|
|
default:
|
|
}
|
|
}
|
|
|
|
// LabelsToSignature returns a unique signature (i.e., fingerprint) for a given
|
|
// label set.
|
|
func LabelsToSignature(labels map[string]string) uint64 {
|
|
if len(labels) == 0 {
|
|
return emptyLabelSignature
|
|
}
|
|
|
|
var result uint64
|
|
hb := getHashAndBuf()
|
|
defer putHashAndBuf(hb)
|
|
|
|
for k, v := range labels {
|
|
hb.b.WriteString(k)
|
|
hb.b.WriteByte(SeparatorByte)
|
|
hb.b.WriteString(v)
|
|
hb.h.Write(hb.b.Bytes())
|
|
result ^= hb.h.Sum64()
|
|
hb.h.Reset()
|
|
hb.b.Reset()
|
|
}
|
|
return result
|
|
}
|
|
|
|
// LabelValuesToSignature returns a unique signature (i.e., fingerprint) for the
|
|
// values of a given label set.
|
|
func LabelValuesToSignature(labels map[string]string) uint64 {
|
|
if len(labels) == 0 {
|
|
return emptyLabelSignature
|
|
}
|
|
|
|
var result uint64
|
|
hb := getHashAndBuf()
|
|
defer putHashAndBuf(hb)
|
|
|
|
for _, v := range labels {
|
|
hb.b.WriteString(v)
|
|
hb.h.Write(hb.b.Bytes())
|
|
result ^= hb.h.Sum64()
|
|
hb.h.Reset()
|
|
hb.b.Reset()
|
|
}
|
|
return result
|
|
}
|