Hold onto a ref of the read buffer to reset it

When reading we will lose reference to the start of the underlying
array because we always reassign it from left to right. Keep a reference
to the underlying full slice so that it can be reset.

frame.go

@@ -233,8 +233,8 @@ const defaultBufSize = 128
 var framerPool = sync.Pool{
 	New: func() interface{} {
 		return &framer{
-			wbuf: make([]byte, defaultBufSize),
-			rbuf: make([]byte, defaultBufSize),
+			wbuf:       make([]byte, defaultBufSize),
+			readBuffer: make([]byte, defaultBufSize),
 		}
 	},
 }
@@ -255,6 +255,10 @@ type framer struct {
 	// if tracing flag is set this is not nil
 	traceID []byte
 
+	// holds a ref to the whole byte slice for rbuf so that it can be reset to
+	// 0 after a read.
+	readBuffer []byte
+
 	rbuf []byte
 	wbuf []byte
 }
@@ -273,14 +277,17 @@ func newFramer(r io.Reader, w io.Writer, compressor Compressor, version byte) *f
 		headSize = 9
 	}
 
-	f.r = r
-	f.w = w
 	f.compres = compressor
 	f.proto = version
 	f.flags = flags
 	f.headSize = headSize
-	f.rbuf = f.rbuf[:0]
+
+	f.r = r
+	f.rbuf = f.readBuffer[:0]
+
+	f.w = w
 	f.wbuf = f.wbuf[:0]
+
 	f.header = nil
 	f.traceID = nil
 
@@ -322,13 +329,14 @@ func (f *framer) trace() {
 
 // reads a frame form the wire into the framers buffer
 func (f *framer) readFrame(head *frameHeader) error {
-	// assume the underlying reader takes care of timeouts and retries
-	if cap(f.rbuf) > head.length {
-		f.rbuf = f.rbuf[:head.length]
+	if cap(f.readBuffer) >= head.length {
+		f.rbuf = f.readBuffer[:head.length]
 	} else {
-		f.rbuf = make([]byte, head.length)
+		f.readBuffer = make([]byte, head.length)
+		f.rbuf = f.readBuffer
 	}
 
+	// assume the underlying reader takes care of timeouts and retries
 	_, err := io.ReadFull(f.r, f.rbuf)
 	if err != nil {
 		return err