refactor

common/buf/buffered_reader.go

@@ -40,8 +40,7 @@ func (v *BufferedReader) Read(b []byte) (int, error) {
 		return v.reader.Read(b)
 	}
 	if v.buffer.IsEmpty() {
-		err := v.buffer.AppendSupplier(ReadFrom(v.reader))
-		if err != nil {
+		if err := v.buffer.Reset(ReadFrom(v.reader)); err != nil {
 			return 0, err
 		}
 	}

common/buf/buffered_writer.go

@@ -28,8 +28,7 @@ func (v *BufferedWriter) Write(b []byte) (int, error) {
 		return 0, err
 	}
 	if v.buffer.IsFull() {
-		err := v.Flush()
-		if err != nil {
+		if err := v.Flush(); err != nil {
 			return 0, err
 		}
 		if nBytes < len(b) {