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35 lines
884 B
Go
35 lines
884 B
Go
//go:build !stringlabels
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package labels
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import (
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"github.com/cespare/xxhash/v2"
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)
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// StableHash is a labels hashing implementation which is guaranteed to not change over time.
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// This function should be used whenever labels hashing backward compatibility must be guaranteed.
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func StableHash(ls Labels) uint64 {
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// Use xxhash.Sum64(b) for fast path as it's faster.
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b := make([]byte, 0, 1024)
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for i, v := range ls {
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if len(b)+len(v.Name)+len(v.Value)+2 >= cap(b) {
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// If labels entry is 1KB+ do not allocate whole entry.
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h := xxhash.New()
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_, _ = h.Write(b)
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for _, v := range ls[i:] {
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_, _ = h.WriteString(v.Name)
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_, _ = h.Write(seps)
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_, _ = h.WriteString(v.Value)
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_, _ = h.Write(seps)
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}
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return h.Sum64()
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}
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b = append(b, v.Name...)
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b = append(b, seps[0])
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b = append(b, v.Value...)
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b = append(b, seps[0])
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}
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return xxhash.Sum64(b)
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}
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