Optimise sanitize with string builder

filters/builtin/stripquery.go

@@ -51,7 +51,8 @@ func validHeaderFieldByte(b byte) bool {
 }
 
 // make sure we don't generate invalid headers
-func sanitize(input string) string {
+// temporary public function to benchmark it
+func Sanitize(input string) string {
 	toAscii := strconv.QuoteToASCII(input)
 	var b bytes.Buffer
 	for _, i := range toAscii {
@@ -62,6 +63,18 @@ func sanitize(input string) string {
 	return b.String()
 }
 
+// temporary public function to benchmark it
+func NewSanitize(input string) string {
+	toAscii := strconv.QuoteToASCII(input)
+	var s strings.Builder
+	for _, i := range toAscii {
+		if validHeaderFieldByte(byte(i)) {
+			s.WriteRune(i)
+		}
+	}
+	return s.String()
+}
+
 // Strips the query parameters and optionally preserves them in the X-Query-Param-xyz headers.
 func (f *stripQuery) Request(ctx filters.FilterContext) {
 	r := ctx.Request()
@@ -85,7 +98,7 @@ func (f *stripQuery) Request(ctx filters.FilterContext) {
 			if r.Header == nil {
 				r.Header = http.Header{}
 			}
-			r.Header.Add(fmt.Sprintf("X-Query-Param-%s", sanitize(k)), v)
+			r.Header.Add(fmt.Sprintf("X-Query-Param-%s", Sanitize(k)), v)
 		}
 	}
 

filters/builtin/stripquery_test.go

@@ -15,11 +15,13 @@
 package builtin
 
 import (
-	"github.com/zalando/skipper/filters/filtertest"
+	"fmt"
 	"net/http"
 	"net/url"
 	"strings"
 	"testing"
+
+	"github.com/zalando/skipper/filters/filtertest"
 )
 
 func TestCreateStripQueryFilter(t *testing.T) {
@@ -91,3 +93,38 @@ func TestPreserveQuery(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkStripQuery(b *testing.B) {
+	var table = []struct {
+		url string
+	}{
+		{url: "http://example.org/foo?bar=baz"},
+		{url: "http://example.org/foo?query=cXVlcnkgewogIG5hbWUKfQo%253D&variables=&apiEndpoint=https%253A%252F%252Fwww.zalando.de%252Fapi%252Fgraphql%252Fpreview&frontendType=web&zalandoFeature=manual"},
+		{url: "http://example.org/foo?馬鹿=123"},
+		{url: "http://example.org/foo?a%20b=123"},
+	}
+
+	for i, v := range table {
+		url, _ := url.ParseRequestURI(v.url)
+		q := url.Query()
+		b.Run(fmt.Sprintf("[old sanitize] url %d", i+1), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				for k := range q {
+					Sanitize(k)
+				}
+			}
+		})
+	}
+
+	for i, v := range table {
+		url, _ := url.ParseRequestURI(v.url)
+		q := url.Query()
+		b.Run(fmt.Sprintf("[new sanitize] url %d", i + 1), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				for k := range q {
+					NewSanitize(k)
+				}
+			}
+		})
+	}
+}

results.md

@@ -0,0 +1,14 @@
+`go test -benchmem -run=^$ -bench ^BenchmarkStripQuery$ -benchtime=10s  github.com/zalando/skipper/filters/builtin`
+
+```
+BenchmarkStripQuery/[old_sanitize]_url_1-8              85732707               118.6 ns/op            80 B/op          4 allocs/op
+BenchmarkStripQuery/[old_sanitize]_url_2-8              14885370               808.2 ns/op           472 B/op         15 allocs/op
+BenchmarkStripQuery/[old_sanitize]_url_3-8              73297474               162.9 ns/op           120 B/op          4 allocs/op
+BenchmarkStripQuery/[old_sanitize]_url_4-8              100000000              114.1 ns/op            80 B/op          4 allocs/op
+
+
+BenchmarkStripQuery/[new_sanitize]_url_1-8              100000000              103.5 ns/op            24 B/op          3 allocs/op
+BenchmarkStripQuery/[new_sanitize]_url_2-8              15854868               778.5 ns/op           192 B/op         14 allocs/op
+BenchmarkStripQuery/[new_sanitize]_url_3-8              71689101               166.3 ns/op            64 B/op          4 allocs/op
+BenchmarkStripQuery/[new_sanitize]_url_4-8              100000000              102.0 ns/op            24 B/op          3 allocs/op
+```