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>
This commit is contained in:
Eli Lindsey
2022-10-09 16:12:39 -04:00
committed by Gopher Robot
parent c877839975
commit a1278a7f7e
2 changed files with 14 additions and 6 deletions

View File

@@ -95,3 +95,11 @@ func lowerHeader(v string) (lower string, ascii bool) {
}
return asciiToLower(v)
}
func canonicalHeader(v string) string {
buildCommonHeaderMapsOnce()
if s, ok := commonCanonHeader[v]; ok {
return s
}
return http.CanonicalHeaderKey(v)
}

View File

@@ -1075,7 +1075,7 @@ var errRequestCanceled = errors.New("net/http: request canceled")
func commaSeparatedTrailers(req *http.Request) (string, error) {
keys := make([]string, 0, len(req.Trailer))
for k := range req.Trailer {
k = http.CanonicalHeaderKey(k)
k = canonicalHeader(k)
switch k {
case "Transfer-Encoding", "Trailer", "Content-Length":
return "", fmt.Errorf("invalid Trailer key %q", k)
@@ -1915,7 +1915,7 @@ func (cc *ClientConn) encodeHeaders(req *http.Request, addGzipHeader bool, trail
// Header list size is ok. Write the headers.
enumerateHeaders(func(name, value string) {
name, ascii := asciiToLower(name)
name, ascii := lowerHeader(name)
if !ascii {
// Skip writing invalid headers. Per RFC 7540, Section 8.1.2, header
// field names have to be ASCII characters (just as in HTTP/1.x).
@@ -1968,7 +1968,7 @@ func (cc *ClientConn) encodeTrailers(trailer http.Header) ([]byte, error) {
}
for k, vv := range trailer {
lowKey, ascii := asciiToLower(k)
lowKey, ascii := lowerHeader(k)
if !ascii {
// Skip writing invalid headers. Per RFC 7540, Section 8.1.2, header
// field names have to be ASCII characters (just as in HTTP/1.x).
@@ -2301,7 +2301,7 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
Status: status + " " + http.StatusText(statusCode),
}
for _, hf := range regularFields {
key := http.CanonicalHeaderKey(hf.Name)
key := canonicalHeader(hf.Name)
if key == "Trailer" {
t := res.Trailer
if t == nil {
@@ -2309,7 +2309,7 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
res.Trailer = t
}
foreachHeaderElement(hf.Value, func(v string) {
t[http.CanonicalHeaderKey(v)] = nil
t[canonicalHeader(v)] = nil
})
} else {
vv := header[key]
@@ -2414,7 +2414,7 @@ func (rl *clientConnReadLoop) processTrailers(cs *clientStream, f *MetaHeadersFr
trailer := make(http.Header)
for _, hf := range f.RegularFields() {
key := http.CanonicalHeaderKey(hf.Name)
key := canonicalHeader(hf.Name)
trailer[key] = append(trailer[key], hf.Value)
}
cs.trailer = trailer