[release-branch.go1.21] Revert "net/http: use Copy in ServeContent if CopyN not needed"

This reverts CL 446276.

Reason for revert: Causing surprising performance regression.

Fixes #61530

Change-Id: Ic970f2e05d875b606ce274ea621f7e4c8c337481
Reviewed-on: https://go-review.googlesource.com/c/go/+/512615
Run-TryBot: Damien Neil <dneil@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
(cherry picked from commit df0a1297899aff1c46b66523e75aa12b0ff5049f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/515795
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Damien Neil <dneil@google.com>

diff --git a/src/net/http/fs.go b/src/net/http/fs.go
index 55094400ac7f2ee68dfa7aeb0a522b68c31e3c26..41e0b43ac819bfdc22e78079fadaa6aa26813214 100644 (file)
--- a/src/net/http/fs.go
+++ b/src/net/http/fs.go
@@ -349,13 +349,8 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 
        w.WriteHeader(code)
 
-       if r.Method != MethodHead {
-               if sendSize == size {
-                       // use Copy in the non-range case to make use of WriterTo if available
-                       io.Copy(w, sendContent)
-               } else {
-                       io.CopyN(w, sendContent, sendSize)
-               }
+       if r.Method != "HEAD" {
+               io.CopyN(w, sendContent, sendSize)
        }
 }
 

diff --git a/src/net/http/fs_test.go b/src/net/http/fs_test.go
index e37e0f04c9bf0cd9ea5abe2226f83c8691f125b9..3fb9e01235e51d4c7a15bcc49df5ee12e3d82575 100644 (file)
--- a/src/net/http/fs_test.go
+++ b/src/net/http/fs_test.go
@@ -924,7 +924,6 @@ func testServeContent(t *testing.T, mode testMode) {
                wantContentType  string
                wantContentRange string
                wantStatus       int
-               wantContent      []byte
        }
        htmlModTime := mustStat(t, "testdata/index.html").ModTime()
        tests := map[string]testCase{
@@ -1140,24 +1139,6 @@ func testServeContent(t *testing.T, mode testMode) {
                        wantStatus:  412,
                        wantLastMod: htmlModTime.UTC().Format(TimeFormat),
                },
-               "uses_writeTo_if_available_and_non-range": {
-                       content:          &panicOnNonWriterTo{seekWriterTo: strings.NewReader("foobar")},
-                       serveContentType: "text/plain; charset=utf-8",
-                       wantContentType:  "text/plain; charset=utf-8",
-                       wantStatus:       StatusOK,
-                       wantContent:      []byte("foobar"),
-               },
-               "do_not_use_writeTo_for_range_requests": {
-                       content:          &panicOnWriterTo{ReadSeeker: strings.NewReader("foobar")},
-                       serveContentType: "text/plain; charset=utf-8",
-                       reqHeader: map[string]string{
-                               "Range": "bytes=0-4",
-                       },
-                       wantContentType:  "text/plain; charset=utf-8",
-                       wantContentRange: "bytes 0-4/6",
-                       wantStatus:       StatusPartialContent,
-                       wantContent:      []byte("fooba"),
-               },
        }
        for testName, tt := range tests {
                var content io.ReadSeeker
@@ -1171,8 +1152,7 @@ func testServeContent(t *testing.T, mode testMode) {
                } else {
                        content = tt.content
                }
-               contentOut := &strings.Builder{}
-               for _, method := range []string{MethodGet, MethodHead} {
+               for _, method := range []string{"GET", "HEAD"} {
                        //restore content in case it is consumed by previous method
                        if content, ok := content.(*strings.Reader); ok {
                                content.Seek(0, io.SeekStart)
@@ -1198,8 +1178,7 @@ func testServeContent(t *testing.T, mode testMode) {
                        if err != nil {
                                t.Fatal(err)
                        }
-                       contentOut.Reset()
-                       io.Copy(contentOut, res.Body)
+                       io.Copy(io.Discard, res.Body)
                        res.Body.Close()
                        if res.StatusCode != tt.wantStatus {
                                t.Errorf("test %q using %q: got status = %d; want %d", testName, method, res.StatusCode, tt.wantStatus)
@@ -1213,28 +1192,10 @@ func testServeContent(t *testing.T, mode testMode) {
                        if g, e := res.Header.Get("Last-Modified"), tt.wantLastMod; g != e {
                                t.Errorf("test %q using %q: got last-modified = %q, want %q", testName, method, g, e)
                        }
-                       if g, e := contentOut.String(), tt.wantContent; e != nil && method == MethodGet && g != string(e) {
-                               t.Errorf("test %q using %q: got unexpected content %q, want %q", testName, method, g, e)
-                       }
                }
        }
 }
 
-type seekWriterTo interface {
-       io.Seeker
-       io.WriterTo
-}
-
-type panicOnNonWriterTo struct {
-       io.Reader
-       seekWriterTo
-}
-
-type panicOnWriterTo struct {
-       io.ReadSeeker
-       io.WriterTo
-}
-
 // Issue 12991
 func TestServerFileStatError(t *testing.T) {
        rec := httptest.NewRecorder()