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Optimize Matcher.String()

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Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
This commit is contained in:
Oleg Zaytsev 2024-05-08 17:05:27 +02:00
parent dabd789fd5
commit 6ebda5a7bc
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GPG Key ID: 7E9FE9FD48F512EF
1 changed files with 15 additions and 4 deletions
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19
model/labels/matcher.go
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@ -14,7 +14,8 @@
package labels
import (
"fmt"
"strconv"
"unsafe"
)
// MatchType is an enum for label matching types.
@ -78,10 +79,20 @@ func MustNewMatcher(mt MatchType, name, val string) *Matcher {
}
func (m *Matcher) String() string {
if !m.shouldQuoteName() {
return fmt.Sprintf("%s%s%q", m.Name, m.Type, m.Value)
const quote = 1
const matcher = 2
// As we're not on go1.22 yet and we don't have the new fancy AvailableBuffer method on strings.Builder,
// we'll use a plain byte slice and then do the unsafe conversion to string just like strings.Builder does.
// We pre-allocate pessimistically for quoting the label name, and optimistically for not having to escape any quotes.
b := make([]byte, 0, quote+len(m.Name)+quote+matcher+quote+len(m.Value)+quote)
if m.shouldQuoteName() {
b = strconv.AppendQuote(b, m.Name)
} else {
b = append(b, m.Name...)
}
return fmt.Sprintf("%q%s%q", m.Name, m.Type, m.Value)
b = append(b, m.Type.String()...)
b = strconv.AppendQuote(b, m.Value)
return *((*string)(unsafe.Pointer(&b)))
}
func (m *Matcher) shouldQuoteName() bool {