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Optimise labels.Compare (#6539)

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strings.Compare isn't meant to be used, and this way we save one
comparison which is thus very slightly cheaper.

benchmark                                     old ns/op     new ns/op delta
BenchmarkPostingsForMatchers/Head/n="1"-4     236305440     233515705 -1.18%

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>
This commit is contained in:
Brian Brazil 2020-01-01 15:45:01 +00:00 committed by GitHub
parent edf8f135bc
commit a9ed3b980d
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1 changed files with 12 additions and 5 deletions
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17
pkg/labels/labels.go
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@ -18,7 +18,6 @@ import (
"encoding/json"
"sort"
"strconv"
"strings"
"github.com/cespare/xxhash"
)
@ -285,11 +284,19 @@ func Compare(a, b Labels) int {
}
for i := 0; i < l; i++ {
if d := strings.Compare(a[i].Name, b[i].Name); d != 0 {
return d
if a[i].Name != b[i].Name {
if a[i].Name < b[i].Name {
return -1
} else {
return 1
}
}
if a[i].Value != b[i].Value {
if a[i].Value < b[i].Value {
return -1
} else {
return 1
}
if d := strings.Compare(a[i].Value, b[i].Value); d != 0 {
return d
}
}
// If all labels so far were in common, the set with fewer labels comes first.