refactor(countrw): move to iout

iout/tee_closer.go

@@ -0,0 +1,28 @@
+package iout
+
+import "io"
+
+type teeCloser struct {
+	r io.ReadCloser
+	w io.WriteCloser
+}
+
+func NewTeeCloser(r io.ReadCloser, w io.WriteCloser) io.ReadCloser {
+	return &teeCloser{r, w}
+}
+
+func (t *teeCloser) Read(p []byte) (int, error) {
+	n, err := t.r.Read(p)
+	if n > 0 {
+		if n, err := t.w.Write(p[:n]); err != nil {
+			return n, err
+		}
+	}
+	return n, err
+}
+
+func (t *teeCloser) Close() error {
+	t.r.Close()
+	t.w.Close()
+	return nil
+}