net/http: support WriteString on the ResponseWriter

Fixes #5377

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12991046

diff --git a/src/pkg/net/http/serve_test.go b/src/pkg/net/http/serve_test.go
index df4367e2b2215b5cca3a698c2d836eadea7a06c7..5d08d2facab75f7cb62d95cf8cabafd643d98284 100644 (file)
--- a/src/pkg/net/http/serve_test.go
+++ b/src/pkg/net/http/serve_test.go
@@ -1994,6 +1994,21 @@ func TestNoContentTypeOnNotModified(t *testing.T) {
        }
 }
 
+func TestResponseWriterWriteStringAllocs(t *testing.T) {
+       ht := newHandlerTest(HandlerFunc(func(w ResponseWriter, r *Request) {
+               if r.URL.Path == "/s" {
+                       io.WriteString(w, "Hello world")
+               } else {
+                       w.Write([]byte("Hello world"))
+               }
+       }))
+       before := testing.AllocsPerRun(25, func() { ht.rawResponse("GET / HTTP/1.0") })
+       after := testing.AllocsPerRun(25, func() { ht.rawResponse("GET /s HTTP/1.0") })
+       if int(after) >= int(before) {
+               t.Errorf("WriteString allocs of %v >= Write allocs of %v", after, before)
+       }
+}
+
 func BenchmarkClientServer(b *testing.B) {
        b.ReportAllocs()
        b.StopTimer()

diff --git a/src/pkg/net/http/server.go b/src/pkg/net/http/server.go
index 9702aee2742c29b4901e4a84463be9de5d503484..3c327839cbb12a8bcfa7950c1045b3217ce4d3c2 100644 (file)
--- a/src/pkg/net/http/server.go
+++ b/src/pkg/net/http/server.go
@@ -953,6 +953,15 @@ func (w *response) bodyAllowed() bool {
 // bufferBeforeChunkingSize smaller and having bufio's fast-paths deal
 // with this instead.
 func (w *response) Write(data []byte) (n int, err error) {
+       return w.write(len(data), data, "")
+}
+
+func (w *response) WriteString(data string) (n int, err error) {
+       return w.write(len(data), nil, data)
+}
+
+// either dataB or dataS is non-zero.
+func (w *response) write(lenData int, dataB []byte, dataS string) (n int, err error) {
        if w.conn.hijacked() {
                log.Print("http: response.Write on hijacked connection")
                return 0, ErrHijacked
@@ -960,18 +969,22 @@ func (w *response) Write(data []byte) (n int, err error) {
        if !w.wroteHeader {
                w.WriteHeader(StatusOK)
        }
-       if len(data) == 0 {
+       if lenData == 0 {
                return 0, nil
        }
        if !w.bodyAllowed() {
                return 0, ErrBodyNotAllowed
        }
 
-       w.written += int64(len(data)) // ignoring errors, for errorKludge
+       w.written += int64(lenData) // ignoring errors, for errorKludge
        if w.contentLength != -1 && w.written > w.contentLength {
                return 0, ErrContentLength
        }
-       return w.w.Write(data)
+       if dataB != nil {
+               return w.w.Write(dataB)
+       } else {
+               return w.w.WriteString(dataS)
+       }
 }
 
 func (w *response) finishRequest() {