http: buffer Request.Write

Fixes #1996

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4639068

src/pkg/http/client_test.go

@@ -12,6 +12,7 @@ import (
 	"http/httptest"
 	"io"
 	"io/ioutil"
+	"net"
 	"os"
 	"strconv"
 	"strings"
@@ -243,3 +244,48 @@ func TestStreamingGet(t *testing.T) {
 		t.Fatalf("at end expected EOF, got %v", err)
 	}
 }
+
+type writeCountingConn struct {
+	net.Conn
+	count *int
+}
+
+func (c *writeCountingConn) Write(p []byte) (int, os.Error) {
+	*c.count++
+	return c.Conn.Write(p)
+}
+
+// TestClientWrites verifies that client requests are buffered and we
+// don't send a TCP packet per line of the http request + body.
+func TestClientWrites(t *testing.T) {
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+	}))
+	defer ts.Close()
+
+	writes := 0
+	dialer := func(netz string, addr string) (net.Conn, os.Error) {
+		c, err := net.Dial(netz, addr)
+		if err == nil {
+			c = &writeCountingConn{c, &writes}
+		}
+		return c, err
+	}
+	c := &Client{Transport: &Transport{Dial: dialer}}
+
+	_, err := c.Get(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if writes != 1 {
+		t.Errorf("Get request did %d Write calls, want 1", writes)
+	}
+
+	writes = 0
+	_, err = c.PostForm(ts.URL, Values{"foo": {"bar"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if writes != 1 {
+		t.Errorf("Post request did %d Write calls, want 1", writes)
+	}
+}

src/pkg/http/request.go

@@ -304,10 +304,11 @@ func (req *Request) write(w io.Writer, usingProxy bool) os.Error {
 		}
 	}
 
-	fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(req.Method, "GET"), uri)
+	bw := bufio.NewWriter(w)
+	fmt.Fprintf(bw, "%s %s HTTP/1.1\r\n", valueOrDefault(req.Method, "GET"), uri)
 
 	// Header lines
-	fmt.Fprintf(w, "Host: %s\r\n", host)
+	fmt.Fprintf(bw, "Host: %s\r\n", host)
 
 	// Use the defaultUserAgent unless the Header contains one, which
 	// may be blank to not send the header.
@@ -318,7 +319,7 @@ func (req *Request) write(w io.Writer, usingProxy bool) os.Error {
 		}
 	}
 	if userAgent != "" {
-		fmt.Fprintf(w, "User-Agent: %s\r\n", userAgent)
+		fmt.Fprintf(bw, "User-Agent: %s\r\n", userAgent)
 	}
 
 	// Process Body,ContentLength,Close,Trailer
@@ -326,25 +327,25 @@ func (req *Request) write(w io.Writer, usingProxy bool) os.Error {
 	if err != nil {
 		return err
 	}
-	err = tw.WriteHeader(w)
+	err = tw.WriteHeader(bw)
 	if err != nil {
 		return err
 	}
 
 	// TODO: split long values?  (If so, should share code with Conn.Write)
-	err = req.Header.WriteSubset(w, reqWriteExcludeHeader)
+	err = req.Header.WriteSubset(bw, reqWriteExcludeHeader)
 	if err != nil {
 		return err
 	}
 
-	io.WriteString(w, "\r\n")
+	io.WriteString(bw, "\r\n")
 
 	// Write body and trailer
-	err = tw.WriteBody(w)
+	err = tw.WriteBody(bw)
 	if err != nil {
 		return err
 	}
-
+	bw.Flush()
 	return nil
 }