8000 perf: Replace O(n) slice scans with O(1) map lookups in NewKey() and NewSection() by Liudon · Pull Request #378 · go-ini/ini · GitHub
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perf: Replace O(n) slice scans with O(1) map lookups in NewKey() and NewSection() #378

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Merged
unknwon merged 3 commits into from
Nov 11, 2026
Merged

perf: Replace O(n) slice scans with O(1) map lookups in NewKey() and NewSection() #378

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f2ea95a
perf: use map lookup instead of slice scan in NewKey() and NewSection()
Liudon Apr 9, 2026
6b8bdec
Merge branch 'main' into fix/optimize-newkey-newsection-lookup
Liudon Aug 11, 2026
615d57e
Check errors in the new benchmarks and run gofmt
unknwon Nov 11, 2026
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45 changes: 45 additions & 0 deletions bench_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
package ini

import (
"fmt"
"testing"
)

Expand Down Expand Up @@ -115,6 +116,50 @@ func Benchmark_Key_SetValue_VisSection(b *testing.B) {
}
}

func Benchmark_NewKey_With_N_Keys(b *testing.B) {
for _, n := range []int{10, 100, 500, 1000} {
b.Run(fmt.Sprintf("keys=%d", n), func(b *testing.B) {
f := Empty()
sec, err := f.NewSection("bench")
if err != nil {
b.Fatal(err)
}
for i := 0; i < n; i++ {
if _, err := sec.NewKey(fmt.Sprintf("key%d", i), "val"); err != nil {
b.Fatal(err)
}
}
target := fmt.Sprintf("key%d", n-1)
b.ResetTimer()
for i := 0; i < b.N; i++ {
if _, err := sec.NewKey(target, "newval"); err != nil {
b.Fatal(err)
}
}
})
}
}

func Benchmark_NewSection_With_N_Sections(b *testing.B) {
for _, n := range []int{10, 100, 500, 1000} {
b.Run(fmt.Sprintf("sections=%d", n), func(b *testing.B) {
f := Empty()
for i := 0; i < n; i++ {
if _, err := f.NewSection(fmt.Sprintf("sec%d", i)); err != nil {
b.Fatal(err)
}
}
target := fmt.Sprintf("sec%d", n-1)
b.ResetTimer()
for i := 0; i < b.N; i++ {
if _, err := f.NewSection(target); err != nil {
b.Fatal(err)
}
}
})
}
}

func Benchmark_Key_Strings_LargeArray(b *testing.B) {
c, err := Load("testdata/large_array.ini")
if err != nil {
Expand Down
2 changes: 1 addition & 1 deletion file.go
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ func (f *File) NewSection(name string) (*Section, error) {
defer f.lock.Unlock()
}

if !f.options.AllowNonUniqueSections && inSlice(name, f.sectionList) {
if !f.options.AllowNonUniqueSections && f.sections[name] != nil {
return f.sections[name][0], nil
}

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24 changes: 0 additions & 24 deletions helper.go
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27 changes: 0 additions & 27 deletions helper_test.go
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2 changes: 1 addition & 1 deletion section.go
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ func (s *Section) NewKey(name, val string) (*Key, error) {
defer s.f.lock.Unlock()
}

if inSlice(name, s.keyList) {
if _, ok := s.keys[name]; ok {
if s.f.options.AllowShadows {
if err := s.keys[name].addShadow(val); err != nil {
return nil, err
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0