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http/httpguts: speed up ValidHeaderFieldName
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Eliminate bounds checks and eschews UTF-8 decoding in ValidHeaderFieldName,
thereby doubling its speed without introducing any allocations.
Also eliminate bounds checks in IsTokenRune.

Add tests and benchmarks for both ValidHeaderFieldName and IsTokenRune.

goos: darwin
goarch: amd64
pkg: golang.org/x/net/http/httpguts
cpu: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
                       │   before    │                after                │
                       │   sec/op    │   sec/op     vs base                │
IsTokenRune-8            315.2n ± 0%   316.2n ± 1%        ~ (p=0.245 n=20)
ValidHeaderFieldName-8   62.77n ± 0%   29.16n ± 0%  -53.55% (p=0.000 n=20)
geomean                  140.7n        96.02n       -31.73%

                       │    before    │                after               │
                       │     B/op     │    B/op     vs base                │
IsTokenRune-8            0.000 ± 0%     0.000 ± 0%       ~ (p=1.000 n=20)
ValidHeaderFieldName-8   0.000 ± 0%     0.000 ± 0%       ~ (p=1.000 n=20)
geomean                             ²               +0.00%

                       │    before    │                after               │
                       │  allocs/op   │ allocs/op   vs base                │
IsTokenRune-8            0.000 ± 0%     0.000 ± 0%       ~ (p=1.000 n=20)
ValidHeaderFieldName-8   0.000 ± 0%     0.000 ± 0%       ~ (p=1.000 n=20)
geomean                             ²               +0.00%

Fixes golang/go#66700

Change-Id: Ia3ea80e5f0d173e3a69eb7429023587fd7bc5933
GitHub-Last-Rev: 1f1d25d
GitHub-Pull-Request: #207
Reviewed-on: https://go-review.googlesource.com/c/net/+/578075
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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Julien Cretel authored and neild committed Apr 15, 2024
1 parent ec05fdc commit 0a24555
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Showing 2 changed files with 52 additions and 10 deletions.
13 changes: 4 additions & 9 deletions http/httpguts/httplex.go
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ import (
"golang.org/x/net/idna"
)

var isTokenTable = [127]bool{
var isTokenTable = [256]bool{
'!': true,
'#': true,
'$': true,
Expand Down Expand Up @@ -93,12 +93,7 @@ var isTokenTable = [127]bool{
}

func IsTokenRune(r rune) bool {
i := int(r)
return i < len(isTokenTable) && isTokenTable[i]
}

func isNotToken(r rune) bool {
return !IsTokenRune(r)
return r < utf8.RuneSelf && isTokenTable[byte(r)]
}

// HeaderValuesContainsToken reports whether any string in values
Expand Down Expand Up @@ -202,8 +197,8 @@ func ValidHeaderFieldName(v string) bool {
if len(v) == 0 {
return false
}
for _, r := range v {
if !IsTokenRune(r) {
for i := 0; i < len(v); i++ {
if !isTokenTable[v[i]] {
return false
}
}
Expand Down
49 changes: 48 additions & 1 deletion http/httpguts/httplex_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ func isSeparator(c rune) bool {
return false
}

func TestIsToken(t *testing.T) {
func TestIsTokenRune(t *testing.T) {
for i := 0; i <= 130; i++ {
r := rune(i)
expected := isChar(r) && !isCtl(r) && !isSeparator(r)
Expand All @@ -30,6 +30,15 @@ func TestIsToken(t *testing.T) {
}
}

func BenchmarkIsTokenRune(b *testing.B) {
for i := 0; i < b.N; i++ {
var r rune
for ; r < 1024; r++ {
IsTokenRune(r)
}
}
}

func TestHeaderValuesContainsToken(t *testing.T) {
tests := []struct {
vals []string
Expand Down Expand Up @@ -100,6 +109,44 @@ func TestHeaderValuesContainsToken(t *testing.T) {
}
}

func TestValidHeaderFieldName(t *testing.T) {
tests := []struct {
in string
want bool
}{
{"", false},
{"Accept Charset", false},
{"Accept-Charset", true},
{"AccepT-EncodinG", true},
{"CONNECTION", true},
{"résumé", false},
}
for _, tt := range tests {
got := ValidHeaderFieldName(tt.in)
if tt.want != got {
t.Errorf("ValidHeaderFieldName(%q) = %t; want %t", tt.in, got, tt.want)
}
}
}

func BenchmarkValidHeaderFieldName(b *testing.B) {
names := []string{
"",
"Accept Charset",
"Accept-Charset",
"AccepT-EncodinG",
"CONNECTION",
"résumé",
}
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
for _, name := range names {
ValidHeaderFieldName(name)
}
}
}

func TestPunycodeHostPort(t *testing.T) {
tests := []struct {
in, want string
Expand Down

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