Remove CloseNotifier for go 1.8+

http.CloseNotifier is deprecated as of Go 1.11, with a note that "the
CloseNotifier interface predates Go's context package. New code should
use Request.Context instead."

Signed-off-by: Maxim Eremenko <moeryomenko@gmail.com>

web/mutil/writer_proxy.go

@@ -1,3 +1,5 @@
+// +build !go1.8
+
 package mutil
 
 import (
@@ -62,6 +64,7 @@ func (b *basicWriter) WriteHeader(code int) {
 		b.ResponseWriter.WriteHeader(code)
 	}
 }
+
 func (b *basicWriter) Write(buf []byte) (int, error) {
 	b.WriteHeader(http.StatusOK)
 	n, err := b.ResponseWriter.Write(buf)
@@ -75,20 +78,25 @@ func (b *basicWriter) Write(buf []byte) (int, error) {
 	b.bytes += n
 	return n, err
 }
+
 func (b *basicWriter) maybeWriteHeader() {
 	if !b.wroteHeader {
 		b.WriteHeader(http.StatusOK)
 	}
 }
+
 func (b *basicWriter) Status() int {
 	return b.code
 }
+
 func (b *basicWriter) BytesWritten() int {
 	return b.bytes
 }
+
 func (b *basicWriter) Tee(w io.Writer) {
 	b.tee = w
 }
+
 func (b *basicWriter) Unwrap() http.ResponseWriter {
 	return b.ResponseWriter
 }
@@ -105,14 +113,17 @@ func (f *fancyWriter) CloseNotify() <-chan bool {
 	cn := f.basicWriter.ResponseWriter.(http.CloseNotifier)
 	return cn.CloseNotify()
 }
+
 func (f *fancyWriter) Flush() {
 	fl := f.basicWriter.ResponseWriter.(http.Flusher)
 	fl.Flush()
 }
+
 func (f *fancyWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
 	hj := f.basicWriter.ResponseWriter.(http.Hijacker)
 	return hj.Hijack()
 }
+
 func (f *fancyWriter) ReadFrom(r io.Reader) (int64, error) {
 	if f.basicWriter.tee != nil {
 		return io.Copy(&f.basicWriter, r)
@@ -122,11 +133,6 @@ func (f *fancyWriter) ReadFrom(r io.Reader) (int64, error) {
 	return rf.ReadFrom(r)
 }
 
-var _ http.CloseNotifier = &fancyWriter{}
-var _ http.Flusher = &fancyWriter{}
-var _ http.Hijacker = &fancyWriter{}
-var _ io.ReaderFrom = &fancyWriter{}
-
 type flushWriter struct {
 	basicWriter
 }
@@ -136,4 +142,10 @@ func (f *flushWriter) Flush() {
 	fl.Flush()
 }
 
-var _ http.Flusher = &flushWriter{}
+var (
+	_ http.CloseNotifier = &fancyWriter{}
+	_ http.Flusher       = &fancyWriter{}
+	_ http.Hijacker      = &fancyWriter{}
+	_ io.ReaderFrom      = &fancyWriter{}
+	_ http.Flusher       = &flushWriter{}
+)

web/mutil/writer_proxy_go1_8.go

@@ -0,0 +1,136 @@
+// +build go1.8
+
+package mutil
+
+import (
+	"bufio"
+	"io"
+	"net"
+	"net/http"
+)
+
+// WriterProxy is a proxy around an http.ResponseWriter that allows you to hook
+// into various parts of the response process.
+type WriterProxy interface {
+	http.ResponseWriter
+	// Status returns the HTTP status of the request, or 0 if one has not
+	// yet been sent.
+	Status() int
+	// BytesWritten returns the total number of bytes sent to the client.
+	BytesWritten() int
+	// Tee causes the response body to be written to the given io.Writer in
+	// addition to proxying the writes through. Only one io.Writer can be
+	// tee'd to at once: setting a second one will overwrite the first.
+	// Writes will be sent to the proxy before being written to this
+	// io.Writer. It is illegal for the tee'd writer to be modified
+	// concurrently with writes.
+	Tee(io.Writer)
+	// Unwrap returns the original proxied target.
+	Unwrap() http.ResponseWriter
+}
+
+// WrapWriter wraps an http.ResponseWriter, returning a proxy that allows you to
+// hook into various parts of the response process.
+func WrapWriter(w http.ResponseWriter) WriterProxy {
+	_, fl := w.(http.Flusher)
+	_, hj := w.(http.Hijacker)
+	_, rf := w.(io.ReaderFrom)
+
+	bw := basicWriter{ResponseWriter: w}
+	if fl && hj && rf {
+		return &fancyWriter{bw}
+	}
+	return &bw
+}
+
+// basicWriter wraps a http.ResponseWriter that implements the minimal
+// http.ResponseWriter interface.
+type basicWriter struct {
+	http.ResponseWriter
+	wroteHeader bool
+	code        int
+	bytes       int
+	tee         io.Writer
+}
+
+func (b *basicWriter) WriteHeader(code int) {
+	if !b.wroteHeader {
+		b.code = code
+		b.wroteHeader = true
+		b.ResponseWriter.WriteHeader(code)
+	}
+}
+
+func (b *basicWriter) Write(buf []byte) (int, error) {
+	b.WriteHeader(http.StatusOK)
+	n, err := b.ResponseWriter.Write(buf)
+	if b.tee != nil {
+		_, err2 := b.tee.Write(buf[:n])
+		// Prefer errors generated by the proxied writer.
+		if err == nil {
+			err = err2
+		}
+	}
+	b.bytes += n
+	return n, err
+}
+
+func (b *basicWriter) maybeWriteHeader() {
+	if !b.wroteHeader {
+		b.WriteHeader(http.StatusOK)
+	}
+}
+
+func (b *basicWriter) Status() int {
+	return b.code
+}
+
+func (b *basicWriter) BytesWritten() int {
+	return b.bytes
+}
+
+func (b *basicWriter) Tee(w io.Writer) {
+	b.tee = w
+}
+
+func (b *basicWriter) Unwrap() http.ResponseWriter {
+	return b.ResponseWriter
+}
+
+// fancyWriter is a writer that additionally satisfies http.Pusher,
+// http.Flusher, http.Hijacker, and io.ReaderFrom. It exists for the common case
+// of wrapping the http.ResponseWriter that package http gives you, in order to
+// make the proxied object support the full method set of the proxied object.
+type fancyWriter struct {
+	basicWriter
+}
+
+func (f *fancyWriter) Push(target string, opts *http.PushOptions) error {
+	return f.basicWriter.ResponseWriter.(http.Pusher).Push(target, opts)
+}
+
+func (f *fancyWriter) Flush() {
+	fl := f.basicWriter.ResponseWriter.(http.Flusher)
+	fl.Flush()
+}
+
+func (f *fancyWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hj := f.basicWriter.ResponseWriter.(http.Hijacker)
+	return hj.Hijack()
+}
+
+func (f *fancyWriter) ReadFrom(r io.Reader) (int64, error) {
+	if f.basicWriter.tee != nil {
+		return io.Copy(&f.basicWriter, r)
+	}
+	rf := f.basicWriter.ResponseWriter.(io.ReaderFrom)
+	f.basicWriter.maybeWriteHeader()
+	return rf.ReadFrom(r)
+}
+
+var (
+	_ http.Pusher   = &fancyWriter{}
+	_ http.Flusher  = &fancyWriter{}
+	_ http.Hijacker = &fancyWriter{}
+	_ io.ReaderFrom = &fancyWriter{}
+)