add observer

stats/wrapper/io.go

@@ -0,0 +1,38 @@
+package wrapper
+
+import (
+	"io"
+
+	"github.com/go-gost/x/stats"
+)
+
+// readWriter is an io.ReadWriter with Stats.
+type readWriter struct {
+	io.ReadWriter
+	stats *stats.Stats
+}
+
+func WrapReadWriter(rw io.ReadWriter, stats *stats.Stats) io.ReadWriter {
+	if stats == nil {
+		return rw
+	}
+
+	return &readWriter{
+		ReadWriter: rw,
+		stats:      stats,
+	}
+}
+
+func (p *readWriter) Read(b []byte) (n int, err error) {
+	n, err = p.ReadWriter.Read(b)
+	p.stats.Add(stats.KindInputBytes, int64(n))
+
+	return
+}
+
+func (p *readWriter) Write(b []byte) (n int, err error) {
+	n, err = p.ReadWriter.Write(b)
+	p.stats.Add(stats.KindOutputBytes, int64(n))
+
+	return
+}