fix: race that causes LocalParticipant to show up as RemoteParticipant (#619)

* fix: race that causes LocalParticipant to show up as RemoteParticipant

RTCEngine.JoinContext starts SignalClient's dispatch loop. If there's an
update to the local participant (in the form of ParticipantUpdate) before
PeerConnection is established, then we would incorrectly categorize the
LocalParticipant as a RemoteParticipant.

* actually call it

* fix staticcheck

Author: davidzhao

engine.go

@@ -83,6 +83,7 @@ type RTCEngine struct {
 	OnResuming              func()
 	OnResumed               func()
 	OnTranscription         func(*livekit.Transcription)
+	OnSignalClientConnected func(*livekit.JoinResponse)
 
 	// callbacks to get data
 	CbGetLocalParticipantSID func() string
@@ -160,6 +161,10 @@ func (e *RTCEngine) JoinContext(ctx context.Context, url string, token string, p
 		return nil, err
 	}
 
+	if e.OnSignalClientConnected != nil {
+		e.OnSignalClientConnected(res)
+	}
+
 	e.client.Start()
 
 	// send offer

regionurlprovider.go

@@ -78,14 +78,19 @@ func (r *regionURLProvider) RefreshRegionSettings(cloudHostname, token string) e
 		return errors.New("refreshRegionSettings failed to decode region settings: " + err.Error())
 	}
 
-	r.mutex.Lock()
-	r.hostnameSettingsCache[cloudHostname] = &hostnameSettingsCacheItem{
+	item := &hostnameSettingsCacheItem{
 		regionSettings:    regions,
 		updatedAt:         time.Now(),
 		regionURLAttempts: map[string]int{},
 	}
+	r.mutex.Lock()
+	r.hostnameSettingsCache[cloudHostname] = item
 	r.mutex.Unlock()
 
+	if len(item.regionSettings.Regions) == 0 {
+		logger.Warnw("no regions returned", nil, "cloudHostname", cloudHostname)
+	}
+
 	return nil
 }
 

room.go

@@ -189,6 +189,7 @@ func NewRoom(callback *RoomCallback) *Room {
 	r.LocalParticipant = newLocalParticipant(engine, r.callback)
 
 	// callbacks from engine
+	engine.OnSignalClientConnected = r.handleSignalClientConnected
 	engine.OnMediaTrack = r.handleMediaTrack
 	engine.OnDisconnected = r.handleDisconnect
 	engine.OnParticipantUpdate = r.handleParticipantUpdate
@@ -328,6 +329,7 @@ func (r *Room) JoinWithToken(url, token string, opts ...ConnectOption) error {
 					d := time.Duration(1<<min(tries, 6)) * time.Second // max 64 seconds
 					logger.Errorw("failed to join room", err,
 						"retrying in", d,
+						"url", bestURL,
 					)
 					time.Sleep(d)
 					continue
@@ -338,32 +340,12 @@ func (r *Room) JoinWithToken(url, token string, opts ...ConnectOption) error {
 
 	if joinRes == nil {
 		var err error
-		joinRes, err = r.engine.JoinContext(ctx, url, token, params)
+		_, err = r.engine.JoinContext(ctx, url, token, params)
 		if err != nil {
 			return err
 		}
 	}
 
-	r.lock.Lock()
-	r.name = joinRes.Room.Name
-	r.metadata = joinRes.Room.Metadata
-	r.serverInfo = joinRes.ServerInfo
-	r.connectionState = ConnectionStateConnected
-	r.sifTrailer = make([]byte, len(joinRes.SifTrailer))
-	copy(r.sifTrailer, joinRes.SifTrailer)
-	r.lock.Unlock()
-
-	r.setSid(joinRes.Room.Sid, false)
-
-	r.LocalParticipant.updateInfo(joinRes.Participant)
-	r.LocalParticipant.updateSubscriptionPermission()
-
-	for _, pi := range joinRes.OtherParticipants {
-		rp := r.addRemoteParticipant(pi, true)
-		r.clearParticipantDefers(livekit.ParticipantID(pi.Sid), pi)
-		r.runParticipantDefers(livekit.ParticipantID(pi.Sid), rp)
-	}
-
 	return nil
 }
 
@@ -552,6 +534,28 @@ func (r *Room) handleMediaTrack(track *webrtc.TrackRemote, receiver *webrtc.RTPR
 	r.runParticipantDefers(livekit.ParticipantID(participantID), rp)
 }
 
+func (r *Room) handleSignalClientConnected(joinRes *livekit.JoinResponse) {
+	r.lock.Lock()
+	r.name = joinRes.Room.Name
+	r.metadata = joinRes.Room.Metadata
+	r.serverInfo = joinRes.ServerInfo
+	r.connectionState = ConnectionStateConnected
+	r.sifTrailer = make([]byte, len(joinRes.SifTrailer))
+	copy(r.sifTrailer, joinRes.SifTrailer)
+	r.lock.Unlock()
+
+	r.setSid(joinRes.Room.Sid, false)
+
+	r.LocalParticipant.updateInfo(joinRes.Participant)
+	r.LocalParticipant.updateSubscriptionPermission()
+
+	for _, pi := range joinRes.OtherParticipants {
+		r.addRemoteParticipant(pi, true)
+		r.clearParticipantDefers(livekit.ParticipantID(pi.Sid), pi)
+		// no need to run participant defers here, since we are connected for the first time
+	}
+}
+
 func (r *Room) handleDisconnect(reason DisconnectionReason) {
 	r.callback.OnDisconnected()
 	r.callback.OnDisconnectedWithReason(reason)