mirror of
https://github.com/prometheus/prometheus.git
synced 2024-11-13 17:14:05 -08:00
48 lines
1.5 KiB
Go
48 lines
1.5 KiB
Go
// Copyright 2020 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.
|
|
|
|
//go:build !stringlabels && !dedupelabels
|
|
|
|
package labels
|
|
|
|
import (
|
|
"github.com/cespare/xxhash/v2"
|
|
)
|
|
|
|
// StableHash is a labels hashing implementation which is guaranteed to not change over time.
|
|
// This function should be used whenever labels hashing backward compatibility must be guaranteed.
|
|
func StableHash(ls Labels) uint64 {
|
|
// Use xxhash.Sum64(b) for fast path as it's faster.
|
|
b := make([]byte, 0, 1024)
|
|
for i, v := range ls {
|
|
if len(b)+len(v.Name)+len(v.Value)+2 >= cap(b) {
|
|
// If labels entry is 1KB+ do not allocate whole entry.
|
|
h := xxhash.New()
|
|
_, _ = h.Write(b)
|
|
for _, v := range ls[i:] {
|
|
_, _ = h.WriteString(v.Name)
|
|
_, _ = h.Write(seps)
|
|
_, _ = h.WriteString(v.Value)
|
|
_, _ = h.Write(seps)
|
|
}
|
|
return h.Sum64()
|
|
}
|
|
|
|
b = append(b, v.Name...)
|
|
b = append(b, seps[0])
|
|
b = append(b, v.Value...)
|
|
b = append(b, seps[0])
|
|
}
|
|
return xxhash.Sum64(b)
|
|
}
|