Make sure client get participant info before track fired (#1147)

pkg/rtc/mediatracksubscriptions.go

@@ -212,6 +212,7 @@ func (t *MediaTrackSubscriptions) AddSubscriber(sub types.LocalParticipant, wr *
 		addTrackParams := types.AddTrackParams{
 			Stereo: info.Stereo,
 		}
+		sub.VerifySubscribeParticipantInfo(subTrack.PublisherID(), subTrack.PublisherVersion())
 		if sub.ProtocolVersion().SupportsTransceiverReuse() {
 			//
 			// AddTrack will create a new transceiver or re-use an unused one

pkg/rtc/participant.go

@@ -86,6 +86,7 @@ type ParticipantParams struct {
 	AdaptiveStream          bool
 	AllowTCPFallback        bool
 	TURNSEnabled            bool
+	GetParticipantInfo      func(pID livekit.ParticipantID) *livekit.ParticipantInfo
 }
 
 type ParticipantImpl struct {
@@ -192,7 +193,7 @@ func NewParticipant(params ParticipantParams) (*ParticipantImpl, error) {
 
 	var err error
 	// keep last participants and when updates were sent
-	if p.updateCache, err = lru.New(32); err != nil {
+	if p.updateCache, err = lru.New(128); err != nil {
 		return nil, err
 	}
 
@@ -858,6 +859,18 @@ func (p *ParticipantImpl) UpdateSubscribedTrackSettings(trackID livekit.TrackID,
 	return nil
 }
 
+func (p *ParticipantImpl) VerifySubscribeParticipantInfo(pID livekit.ParticipantID, version uint32) {
+	if v, ok := p.updateCache.Get(pID); ok && v.(uint32) >= version {
+		return
+	}
+
+	if f := p.params.GetParticipantInfo; f != nil {
+		if info := f(pID); info != nil {
+			p.SendParticipantUpdate([]*livekit.ParticipantInfo{info})
+		}
+	}
+}
+
 // AddSubscribedTrack adds a track to the participant's subscribed list
 func (p *ParticipantImpl) AddSubscribedTrack(subTrack types.SubscribedTrack) {
 	p.lock.Lock()

pkg/rtc/types/interfaces.go

@@ -273,6 +273,7 @@ type LocalParticipant interface {
 	RemoveSubscribedTrack(st SubscribedTrack)
 	UpdateSubscribedTrackSettings(trackID livekit.TrackID, settings *livekit.UpdateTrackSettings) error
 	GetSubscribedTracks() []SubscribedTrack
+	VerifySubscribeParticipantInfo(pID livekit.ParticipantID, version uint32)
 
 	// returns list of participant identities that the current participant is subscribed to
 	GetSubscribedParticipants() []livekit.ParticipantID

pkg/rtc/types/typesfakes/fake_local_participant.go

@@ -755,6 +755,12 @@ type FakeLocalParticipant struct {
 	updateVideoLayersReturnsOnCall map[int]struct {
 		result1 error
 	}
+	VerifySubscribeParticipantInfoStub        func(livekit.ParticipantID, uint32)
+	verifySubscribeParticipantInfoMutex       sync.RWMutex
+	verifySubscribeParticipantInfoArgsForCall []struct {
+		arg1 livekit.ParticipantID
+		arg2 uint32
+	}
 	invocations      map[string][][]interface{}
 	invocationsMutex sync.RWMutex
 }
@@ -4750,6 +4756,39 @@ func (fake *FakeLocalParticipant) UpdateVideoLayersReturnsOnCall(i int, result1
 	}{result1}
 }
 
+func (fake *FakeLocalParticipant) VerifySubscribeParticipantInfo(arg1 livekit.ParticipantID, arg2 uint32) {
+	fake.verifySubscribeParticipantInfoMutex.Lock()
+	fake.verifySubscribeParticipantInfoArgsForCall = append(fake.verifySubscribeParticipantInfoArgsForCall, struct {
+		arg1 livekit.ParticipantID
+		arg2 uint32
+	}{arg1, arg2})
+	stub := fake.VerifySubscribeParticipantInfoStub
+	fake.recordInvocation("VerifySubscribeParticipantInfo", []interface{}{arg1, arg2})
+	fake.verifySubscribeParticipantInfoMutex.Unlock()
+	if stub != nil {
+		fake.VerifySubscribeParticipantInfoStub(arg1, arg2)
+	}
+}
+
+func (fake *FakeLocalParticipant) VerifySubscribeParticipantInfoCallCount() int {
+	fake.verifySubscribeParticipantInfoMutex.RLock()
+	defer fake.verifySubscribeParticipantInfoMutex.RUnlock()
+	return len(fake.verifySubscribeParticipantInfoArgsForCall)
+}
+
+func (fake *FakeLocalParticipant) VerifySubscribeParticipantInfoCalls(stub func(livekit.ParticipantID, uint32)) {
+	fake.verifySubscribeParticipantInfoMutex.Lock()
+	defer fake.verifySubscribeParticipantInfoMutex.Unlock()
+	fake.VerifySubscribeParticipantInfoStub = stub
+}
+
+func (fake *FakeLocalParticipant) VerifySubscribeParticipantInfoArgsForCall(i int) (livekit.ParticipantID, uint32) {
+	fake.verifySubscribeParticipantInfoMutex.RLock()
+	defer fake.verifySubscribeParticipantInfoMutex.RUnlock()
+	argsForCall := fake.verifySubscribeParticipantInfoArgsForCall[i]
+	return argsForCall.arg1, argsForCall.arg2
+}
+
 func (fake *FakeLocalParticipant) Invocations() map[string][][]interface{} {
 	fake.invocationsMutex.RLock()
 	defer fake.invocationsMutex.RUnlock()
@@ -4923,6 +4962,8 @@ func (fake *FakeLocalParticipant) Invocations() map[string][][]interface{} {
 	defer fake.updateSubscriptionPermissionMutex.RUnlock()
 	fake.updateVideoLayersMutex.RLock()
 	defer fake.updateVideoLayersMutex.RUnlock()
+	fake.verifySubscribeParticipantInfoMutex.RLock()
+	defer fake.verifySubscribeParticipantInfoMutex.RUnlock()
 	copiedInvocations := map[string][][]interface{}{}
 	for key, value := range fake.invocations {
 		copiedInvocations[key] = value

pkg/service/roommanager.go

@@ -297,6 +297,12 @@ func (r *RoomManager) StartSession(
 		AdaptiveStream:          pi.AdaptiveStream,
 		AllowTCPFallback:        allowFallback,
 		TURNSEnabled:            r.config.IsTURNSEnabled(),
+		GetParticipantInfo: func(pID livekit.ParticipantID) *livekit.ParticipantInfo {
+			if p := room.GetParticipantBySid(pID); p != nil {
+				return p.ToProto()
+			}
+			return nil
+		},
 	})
 	if err != nil {
 		return err