Keep congestion state only in BWE. (#3224)

pkg/sfu/bwe/bwe.go

@@ -71,6 +71,8 @@ type BWE interface {
 
 	HandleTWCCFeedback(report *rtcp.TransportLayerCC)
 
+	CongestionState() CongestionState
+
 	ProbeClusterStarting(pci ccutils.ProbeClusterInfo)
 	ProbeClusterDone(pci ccutils.ProbeClusterInfo) (bool, int64)
 }

pkg/sfu/bwe/null_bwe.go

@@ -42,6 +42,10 @@ func (n *NullBWE) HandleREMB(
 
 func (n *NullBWE) HandleTWCCFeedback(_report *rtcp.TransportLayerCC) {}
 
+func (n *NullBWE) CongestionState() CongestionState {
+	return CongestionStateNone
+}
+
 func (n *NullBWE) ProbeClusterStarting(_pci ccutils.ProbeClusterInfo) {}
 
 func (n *NullBWE) ProbeClusterDone(_pci ccutils.ProbeClusterInfo) (bool, int64) {

pkg/sfu/bwe/remotebwe/remote_bwe.go

@@ -136,6 +136,13 @@ func (r *RemoteBWE) HandleREMB(
 	}
 }
 
+func (r *RemoteBWE) CongestionState() bwe.CongestionState {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
+
+	return r.congestionState
+}
+
 func (r *RemoteBWE) congestionDetectionStateMachine() (bool, bwe.CongestionState, int64) {
 	newState := r.congestionState
 	update := false

pkg/sfu/bwe/sendsidebwe/congestion_detector.go

@@ -331,6 +331,8 @@ func newCongestionDetector(params congestionDetectorParams) *congestionDetector
 		twccFeedback:                      newTWCCFeedback(twccFeedbackParams{Logger: params.Logger}),
 		wake:                              make(chan struct{}, 1),
 		estimatedAvailableChannelCapacity: 100_000_000,
+		congestionState:                   bwe.CongestionStateNone,
+		congestionStateSwitchedAt:         mono.Now(),
 	}
 
 	c.feedbackReports.SetMinCapacity(3)
@@ -339,14 +341,6 @@ func newCongestionDetector(params congestionDetectorParams) *congestionDetector
 	return c
 }
 
-func (c *congestionDetector) Reset() {
-	// SSBWE-TODO
-	//  1. may be clear all packet groups?
-	//  2. reset congestion state to none
-	//  3. reset estimate to 100 Mbps
-	//  4. reset packet_tracker?? maybe only the probe state??
-}
-
 func (c *congestionDetector) Stop() {
 	c.stop.Break()
 }
@@ -377,6 +371,13 @@ func (c *congestionDetector) HandleTWCCFeedback(report *rtcp.TransportLayerCC) {
 	}
 }
 
+func (c *congestionDetector) CongestionState() bwe.CongestionState {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	return c.congestionState
+}
+
 func (c *congestionDetector) prunePacketGroups() {
 	if len(c.packetGroups) == 0 {
 		return

pkg/sfu/bwe/sendsidebwe/send_side_bwe.go

@@ -90,7 +90,10 @@ func (s *SendSideBWE) SetBWEListener(bweListener bwe.BWEListener) {
 }
 
 func (s *SendSideBWE) Reset() {
-	s.congestionDetector.Reset()
+	s.congestionDetector = newCongestionDetector(congestionDetectorParams{
+		Config: s.params.Config.CongestionDetector,
+		Logger: s.params.Logger,
+	})
 }
 
 func (s *SendSideBWE) Stop() {
@@ -101,4 +104,8 @@ func (s *SendSideBWE) HandleTWCCFeedback(report *rtcp.TransportLayerCC) {
 	s.congestionDetector.HandleTWCCFeedback(report)
 }
 
+func (s *SendSideBWE) CongestionState() bwe.CongestionState {
+	return s.congestionDetector.CongestionState()
+}
+
 // ------------------------------------------------

pkg/sfu/streamallocator/streamallocator.go

@@ -203,9 +203,8 @@ type StreamAllocator struct {
 	isAllocateAllPending bool
 	rembTrackingSSRC     uint32
 
-	state           streamAllocatorState
-	congestionState bwe.CongestionState
-	isHolding       bool
+	state     streamAllocatorState
+	isHolding bool
 
 	eventsQueue *utils.TypedOpsQueue[Event]
 
@@ -220,9 +219,8 @@ func NewStreamAllocator(params StreamAllocatorParams, enabled bool, allowPause b
 		enabled:    enabled,
 		allowPause: allowPause,
 		// STREAM-ALLOCATOR-DATA rateMonitor: NewRateMonitor(),
-		videoTracks:     make(map[livekit.TrackID]*Track),
-		state:           streamAllocatorStateStable,
-		congestionState: bwe.CongestionStateNone,
+		videoTracks: make(map[livekit.TrackID]*Track),
+		state:       streamAllocatorStateStable,
 		eventsQueue: utils.NewTypedOpsQueue[Event](utils.OpsQueueParams{
 			Name:    "stream-allocator",
 			MinSize: 64,
@@ -881,8 +879,6 @@ func (s *StreamAllocator) handleSignalCongestionStateChange(event Event) {
 			s.allocateAllTracks()
 		}
 	}
-
-	s.congestionState = cscd.congestionState
 }
 
 func (s *StreamAllocator) setState(state streamAllocatorState) {
@@ -1302,7 +1298,7 @@ func (s *StreamAllocator) maybeProbe() {
 		return
 	}
 
-	if s.congestionState != bwe.CongestionStateNone || !s.probeController.CanProbe() {
+	if s.params.BWE.CongestionState() != bwe.CongestionStateNone || !s.probeController.CanProbe() {
 		return
 	}