client_golang/prometheus/signature.go

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// Copyright (c) 2013, Prometheus Team
// All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package prometheus
import (
"fmt"
"hash/fnv"
"sort"
"github.com/prometheus/client_golang/model"
)
// cache the signature of an empty label set.
var emptyLabelSignature = fnv.New64a().Sum64()
// LabelsToSignature provides a way of building a unique signature
// (i.e., fingerprint) for a given label set sequence.
func labelsToSignature(labels map[string]string) uint64 {
if len(labels) == 0 {
return emptyLabelSignature
}
names := make(model.LabelNames, 0, len(labels))
for name := range labels {
names = append(names, model.LabelName(name))
}
sort.Sort(names)
hasher := fnv.New64a()
for _, name := range names {
fmt.Fprintf(hasher, string(name), labels[string(name)])
}
return hasher.Sum64()
}