feat(countrw): add countrw package

countrw/cr.go

@@ -0,0 +1,26 @@
+package countrw
+
+import (
+	"io"
+	"sync/atomic"
+)
+
+type CountReader struct {
+	r io.Reader
+	c *uint64
+}
+
+func NewCountReader(r io.Reader) *CountReader {
+	return &CountReader{r: r, c: new(uint64)}
+}
+
+func (c *CountReader) Reset()        { atomic.StoreUint64(c.c, 0) }
+func (c *CountReader) Count() uint64 { return atomic.LoadUint64(c.c) }
+
+func (c *CountReader) Read(p []byte) (int, error) {
+	n, err := c.r.Read(p)
+	atomic.AddUint64(c.c, uint64(n))
+	return n, err
+}
+
+var _ io.Reader = (*CountReader)(nil)

countrw/cw.go

@@ -0,0 +1,26 @@
+package countrw
+
+import (
+	"io"
+	"sync/atomic"
+)
+
+type CountWriter struct {
+	r io.Writer
+	c *uint64
+}
+
+func NewCountWriter(r io.Writer) *CountWriter {
+	return &CountWriter{r: r, c: new(uint64)}
+}
+
+func (c *CountWriter) Reset()        { atomic.StoreUint64(c.c, 0) }
+func (c *CountWriter) Count() uint64 { return atomic.LoadUint64(c.c) }
+
+func (c *CountWriter) Write(p []byte) (int, error) {
+	n, err := c.r.Write(p)
+	atomic.AddUint64(c.c, uint64(n))
+	return n, err
+}
+
+var _ io.Writer = (*CountWriter)(nil)