Add Close method for UpDataTrackManager and call it on participant (#4432)

* Add `Close` method for UpDataTrackManager and call it on participant
close.

* include out-of-order packets in total packets

pkg/rtc/datatrack_stats.go

@@ -65,6 +65,7 @@ func (d *dataTrackStats) Update(packet *datatrack.Packet, arrivalTime int64) {
 			return
 
 		case diff > (1 << 15): // out of order
+			d.numPackets++
 			d.numPacketsOutOfOrder++
 			if d.numPacketsLost > 0 {
 				d.numPacketsLost--

pkg/rtc/participant.go

@@ -1427,6 +1427,7 @@ func (p *ParticipantImpl) Close(sendLeave bool, reason types.ParticipantCloseRea
 	p.pendingTracksLock.Unlock()
 
 	p.UpTrackManager.Close(isExpectedToResume)
+	p.UpDataTrackManager.Close()
 
 	p.rpcLock.Lock()
 	clear(p.rpcPendingAcks)

pkg/rtc/updatatrackmanager.go

@@ -34,6 +34,7 @@ type UpDataTrackManager struct {
 
 	lock       sync.RWMutex
 	dataTracks map[uint16]types.DataTrack
+	closed     bool
 
 	onDataTrackPublished   func(types.Participant, types.DataTrack)
 	onDataTrackUnpublished func(types.Participant, types.DataTrack)
@@ -46,6 +47,24 @@ func NewUpDataTrackManager(params UpDataTrackManagerParams) *UpDataTrackManager
 	}
 }
 
+func (u *UpDataTrackManager) Close() {
+	u.lock.Lock()
+	if u.closed {
+		u.lock.Unlock()
+		return
+	}
+
+	u.closed = true
+
+	dataTracks := u.dataTracks
+	u.dataTracks = make(map[uint16]types.DataTrack)
+	u.lock.Unlock()
+
+	for _, t := range dataTracks {
+		t.Close()
+	}
+}
+
 func (u *UpDataTrackManager) AddPublishedDataTrack(dt types.DataTrack) {
 	u.lock.Lock()
 	u.dataTracks[dt.PubHandle()] = dt