http2: reduce init-time work & allocations
Updates golang/go#26775
Change-Id: Iea95ea07bb0fed42410efb4e8420d8e9a17704fe
Reviewed-on: https://go-review.googlesource.com/127664
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/http2/headermap.go b/http2/headermap.go
index c2805f6..c3ff3fa 100644
--- a/http2/headermap.go
+++ b/http2/headermap.go
@@ -7,15 +7,21 @@
import (
"net/http"
"strings"
+ "sync"
)
var (
- commonLowerHeader = map[string]string{} // Go-Canonical-Case -> lower-case
- commonCanonHeader = map[string]string{} // lower-case -> Go-Canonical-Case
+ commonBuildOnce sync.Once
+ commonLowerHeader map[string]string // Go-Canonical-Case -> lower-case
+ commonCanonHeader map[string]string // lower-case -> Go-Canonical-Case
)
-func init() {
- for _, v := range []string{
+func buildCommonHeaderMapsOnce() {
+ commonBuildOnce.Do(buildCommonHeaderMaps)
+}
+
+func buildCommonHeaderMaps() {
+ common := []string{
"accept",
"accept-charset",
"accept-encoding",
@@ -63,7 +69,10 @@
"vary",
"via",
"www-authenticate",
- } {
+ }
+ commonLowerHeader = make(map[string]string, len(common))
+ commonCanonHeader = make(map[string]string, len(common))
+ for _, v := range common {
chk := http.CanonicalHeaderKey(v)
commonLowerHeader[chk] = v
commonCanonHeader[v] = chk
@@ -71,6 +80,7 @@
}
func lowerHeader(v string) string {
+ buildCommonHeaderMapsOnce()
if s, ok := commonLowerHeader[v]; ok {
return s
}
diff --git a/http2/http2.go b/http2/http2.go
index c824282..bdaba1d 100644
--- a/http2/http2.go
+++ b/http2/http2.go
@@ -201,19 +201,12 @@
return true
}
-var httpCodeStringCommon = map[int]string{} // n -> strconv.Itoa(n)
-
-func init() {
- for i := 100; i <= 999; i++ {
- if v := http.StatusText(i); v != "" {
- httpCodeStringCommon[i] = strconv.Itoa(i)
- }
- }
-}
-
func httpCodeString(code int) string {
- if s, ok := httpCodeStringCommon[code]; ok {
- return s
+ switch code {
+ case 200:
+ return "200"
+ case 404:
+ return "404"
}
return strconv.Itoa(code)
}
diff --git a/http2/server.go b/http2/server.go
index 9862dad..56859d1 100644
--- a/http2/server.go
+++ b/http2/server.go
@@ -663,6 +663,7 @@
func (sc *serverConn) canonicalHeader(v string) string {
sc.serveG.check()
+ buildCommonHeaderMapsOnce()
cv, ok := commonCanonHeader[v]
if ok {
return cv
