api, metrics: add number of bytes received and sent from/to all entities (#1235)

* API: number of bytes received/sent from/to RTSP connections
* API: number of bytes received/sent from/to RTSP sessions
* API: number of bytes received/sent from/to RTMP connections
* API: number of bytes sent to HLS connections
* API: number of bytes received from paths
* metrics of all the above

internal/rtmp/bytecounter/reader.go

@@ -1,42 +1,36 @@
 package bytecounter
 
 import (
-	"bufio"
 	"io"
+	"sync/atomic"
 )
 
-type readerInner struct {
-	r     io.Reader
-	count uint32
-}
-
-func (r *readerInner) Read(p []byte) (int, error) {
-	n, err := r.r.Read(p)
-	r.count += uint32(n)
-	return n, err
-}
-
 // Reader allows to count read bytes.
 type Reader struct {
-	ri *readerInner
-	*bufio.Reader
+	r     io.Reader
+	count uint64
 }
 
 // NewReader allocates a Reader.
 func NewReader(r io.Reader) *Reader {
-	ri := &readerInner{r: r}
 	return &Reader{
-		ri:     ri,
-		Reader: bufio.NewReader(ri),
+		r: r,
 	}
 }
 
-// Count returns read bytes.
-func (r Reader) Count() uint32 {
-	return r.ri.count
+// Read implements io.Reader.
+func (r *Reader) Read(p []byte) (int, error) {
+	n, err := r.r.Read(p)
+	atomic.AddUint64(&r.count, uint64(n))
+	return n, err
+}
+
+// Count returns received bytes.
+func (r *Reader) Count() uint64 {
+	return atomic.LoadUint64(&r.count)
 }
 
 // SetCount sets read bytes.
-func (r *Reader) SetCount(v uint32) {
-	r.ri.count = v
+func (r *Reader) SetCount(v uint64) {
+	atomic.StoreUint64(&r.count, v)
 }