mirror of https://github.com/prometheus/prometheus
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
47 lines
1.5 KiB
47 lines
1.5 KiB
// 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) |
|
}
|
|
|