Files
golang.net/http2/headermap.go
Eli Lindsey a1278a7f7e http2: add common header caching to Transport to reduce allocations
Currently Server builds two process-global maps to cut down allocations
due to lower-casing and canonicalization of common headers.

Lower-casing/canonicalization has also been a significant source of
garbage in Transport - this change extends use of the same
process-global maps to the client.

Change-Id: I2324c9567a61f28d4dd633a2c0618f08ddbf457c
Reviewed-on: https://go-review.googlesource.com/c/net/+/442175
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Damien Neil <dneil@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
2022-11-02 18:17:56 +00:00

106 lines
2.2 KiB
Go

// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package http2
import (
"net/http"
"sync"
)
var (
commonBuildOnce sync.Once
commonLowerHeader map[string]string // Go-Canonical-Case -> lower-case
commonCanonHeader map[string]string // lower-case -> Go-Canonical-Case
)
func buildCommonHeaderMapsOnce() {
commonBuildOnce.Do(buildCommonHeaderMaps)
}
func buildCommonHeaderMaps() {
common := []string{
"accept",
"accept-charset",
"accept-encoding",
"accept-language",
"accept-ranges",
"age",
"access-control-allow-credentials",
"access-control-allow-headers",
"access-control-allow-methods",
"access-control-allow-origin",
"access-control-expose-headers",
"access-control-max-age",
"access-control-request-headers",
"access-control-request-method",
"allow",
"authorization",
"cache-control",
"content-disposition",
"content-encoding",
"content-language",
"content-length",
"content-location",
"content-range",
"content-type",
"cookie",
"date",
"etag",
"expect",
"expires",
"from",
"host",
"if-match",
"if-modified-since",
"if-none-match",
"if-unmodified-since",
"last-modified",
"link",
"location",
"max-forwards",
"origin",
"proxy-authenticate",
"proxy-authorization",
"range",
"referer",
"refresh",
"retry-after",
"server",
"set-cookie",
"strict-transport-security",
"trailer",
"transfer-encoding",
"user-agent",
"vary",
"via",
"www-authenticate",
"x-forwarded-for",
"x-forwarded-proto",
}
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
}
}
func lowerHeader(v string) (lower string, ascii bool) {
buildCommonHeaderMapsOnce()
if s, ok := commonLowerHeader[v]; ok {
return s, true
}
return asciiToLower(v)
}
func canonicalHeader(v string) string {
buildCommonHeaderMapsOnce()
if s, ok := commonCanonHeader[v]; ok {
return s
}
return http.CanonicalHeaderKey(v)
}