net/http: avoid a bunch of unnecessary CanonicalHeaderKey calls

CanonicalHeaderKey didn't allocate, but it did use unnecessary
CPU in the hot path, deciding it didn't need to allocate.

I considered using constants for all these common header keys
but I didn't think it would be prettier. "Content-Length" looks
better than contentLength or hdrContentLength, etc.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/6255053

diff --git a/src/pkg/net/http/header.go b/src/pkg/net/http/header.go
index 7987036222c9623339a9593976c8cc42b1a14d2d..95bfa141504924af3c49f4607ec4046deb576163 100644 (file)
--- a/src/pkg/net/http/header.go
+++ b/src/pkg/net/http/header.go
@@ -36,6 +36,14 @@ func (h Header) Get(key string) string {
        return textproto.MIMEHeader(h).Get(key)
 }
 
+// get is like Get, but key must already be in CanonicalHeaderKey form.
+func (h Header) get(key string) string {
+       if v := h[key]; len(v) > 0 {
+               return v[0]
+       }
+       return ""
+}
+
 // Del deletes the values associated with key.
 func (h Header) Del(key string) {
        textproto.MIMEHeader(h).Del(key)

diff --git a/src/pkg/net/http/request.go b/src/pkg/net/http/request.go
index 784dd6b3224e33a242859f3fbd49d0ba3aecf080..f42d43e404831d098ba78a9be1e665ae739c9a89 100644 (file)
--- a/src/pkg/net/http/request.go
+++ b/src/pkg/net/http/request.go
@@ -513,7 +513,7 @@ func ReadRequest(b *bufio.Reader) (req *Request, err error) {
        // the same.  In the second case, any Host line is ignored.
        req.Host = req.URL.Host
        if req.Host == "" {
-               req.Host = req.Header.Get("Host")
+               req.Host = req.Header.get("Host")
        }
        req.Header.Del("Host")
 
@@ -732,16 +732,16 @@ func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, e
 }
 
 func (r *Request) expectsContinue() bool {
-       return hasToken(r.Header.Get("Expect"), "100-continue")
+       return hasToken(r.Header.get("Expect"), "100-continue")
 }
 
 func (r *Request) wantsHttp10KeepAlive() bool {
        if r.ProtoMajor != 1 || r.ProtoMinor != 0 {
                return false
        }
-       return hasToken(r.Header.Get("Connection"), "keep-alive")
+       return hasToken(r.Header.get("Connection"), "keep-alive")
 }
 
 func (r *Request) wantsClose() bool {
-       return hasToken(r.Header.Get("Connection"), "close")
+       return hasToken(r.Header.get("Connection"), "close")
 }

diff --git a/src/pkg/net/http/server.go b/src/pkg/net/http/server.go
index 0b97de3c219c84523bb10a1b45cd7096bc1d3366..a0cdb7c5698198b4298b1948bef0e6fe568c1283 100644 (file)
--- a/src/pkg/net/http/server.go
+++ b/src/pkg/net/http/server.go
@@ -287,7 +287,7 @@ func (w *response) WriteHeader(code int) {
        // Check for a explicit (and valid) Content-Length header.
        var hasCL bool
        var contentLength int64
-       if clenStr := w.header.Get("Content-Length"); clenStr != "" {
+       if clenStr := w.header.get("Content-Length"); clenStr != "" {
                var err error
                contentLength, err = strconv.ParseInt(clenStr, 10, 64)
                if err == nil {
@@ -307,7 +307,7 @@ func (w *response) WriteHeader(code int) {
                w.closeAfterReply = true
        }
 
-       if w.header.Get("Connection") == "close" {
+       if w.header.get("Connection") == "close" {
                w.closeAfterReply = true
        }
 
@@ -331,7 +331,7 @@ func (w *response) WriteHeader(code int) {
        if code == StatusNotModified {
                // Must not have body.
                for _, header := range []string{"Content-Type", "Content-Length", "Transfer-Encoding"} {
-                       if w.header.Get(header) != "" {
+                       if w.header.get(header) != "" {
                                // TODO: return an error if WriteHeader gets a return parameter
                                // or set a flag on w to make future Writes() write an error page?
                                // for now just log and drop the header.
@@ -341,7 +341,7 @@ func (w *response) WriteHeader(code int) {
                }
        } else {
                // If no content type, apply sniffing algorithm to body.
-               if w.header.Get("Content-Type") == "" && w.req.Method != "HEAD" {
+               if w.header.get("Content-Type") == "" && w.req.Method != "HEAD" {
                        w.needSniff = true
                }
        }
@@ -350,7 +350,7 @@ func (w *response) WriteHeader(code int) {
                w.Header().Set("Date", time.Now().UTC().Format(TimeFormat))
        }
 
-       te := w.header.Get("Transfer-Encoding")
+       te := w.header.get("Transfer-Encoding")
        hasTE := te != ""
        if hasCL && hasTE && te != "identity" {
                // TODO: return an error if WriteHeader gets a return parameter
@@ -390,7 +390,7 @@ func (w *response) WriteHeader(code int) {
                return
        }
 
-       if w.closeAfterReply && !hasToken(w.header.Get("Connection"), "close") {
+       if w.closeAfterReply && !hasToken(w.header.get("Connection"), "close") {
                w.header.Set("Connection", "close")
        }
 
@@ -515,8 +515,8 @@ func (w *response) finishRequest() {
        // If this was an HTTP/1.0 request with keep-alive and we sent a Content-Length
        // back, we can make this a keep-alive response ...
        if w.req.wantsHttp10KeepAlive() {
-               sentLength := w.header.Get("Content-Length") != ""
-               if sentLength && w.header.Get("Connection") == "keep-alive" {
+               sentLength := w.header.get("Content-Length") != ""
+               if sentLength && w.header.get("Connection") == "keep-alive" {
                        w.closeAfterReply = false
                }
        }
@@ -628,7 +628,7 @@ func (c *conn) serve() {
                                break
                        }
                        req.Header.Del("Expect")
-               } else if req.Header.Get("Expect") != "" {
+               } else if req.Header.get("Expect") != "" {
                        // TODO(bradfitz): let ServeHTTP handlers handle
                        // requests with non-standard expectation[s]? Seems
                        // theoretical at best, and doesn't fit into the

diff --git a/src/pkg/net/http/transfer.go b/src/pkg/net/http/transfer.go
index 9e9d84172d00effda81bb0ee7e45739d5a161f8e..1fc1e63a960e33b96da3a5b6ad7f33cce301996e 100644 (file)
--- a/src/pkg/net/http/transfer.go
+++ b/src/pkg/net/http/transfer.go
@@ -432,7 +432,7 @@ func fixLength(isResponse bool, status int, requestMethod string, header Header,
        }
 
        // Logic based on Content-Length
-       cl := strings.TrimSpace(header.Get("Content-Length"))
+       cl := strings.TrimSpace(header.get("Content-Length"))
        if cl != "" {
                n, err := strconv.ParseInt(cl, 10, 64)
                if err != nil || n < 0 {
@@ -454,7 +454,7 @@ func fixLength(isResponse bool, status int, requestMethod string, header Header,
        // Logic based on media type. The purpose of the following code is just
        // to detect whether the unsupported "multipart/byteranges" is being
        // used. A proper Content-Type parser is needed in the future.
-       if strings.Contains(strings.ToLower(header.Get("Content-Type")), "multipart/byteranges") {
+       if strings.Contains(strings.ToLower(header.get("Content-Type")), "multipart/byteranges") {
                return -1, ErrNotSupported
        }
 
@@ -469,14 +469,14 @@ func shouldClose(major, minor int, header Header) bool {
        if major < 1 {
                return true
        } else if major == 1 && minor == 0 {
-               if !strings.Contains(strings.ToLower(header.Get("Connection")), "keep-alive") {
+               if !strings.Contains(strings.ToLower(header.get("Connection")), "keep-alive") {
                        return true
                }
                return false
        } else {
                // TODO: Should split on commas, toss surrounding white space,
                // and check each field.
-               if strings.ToLower(header.Get("Connection")) == "close" {
+               if strings.ToLower(header.get("Connection")) == "close" {
                        header.Del("Connection")
                        return true
                }
@@ -486,7 +486,7 @@ func shouldClose(major, minor int, header Header) bool {
 
 // Parse the trailer header
 func fixTrailer(header Header, te []string) (Header, error) {
-       raw := header.Get("Trailer")
+       raw := header.get("Trailer")
        if raw == "" {
                return nil, nil
        }