Log RPC details. (#3991)

Seeing cases of `ConnectionTimeout` and `ResponseTimeout`.
So, logging destination identity in RPC request and also logging ACK and
response. Will pare back logs/log level of these messages after gettnig
some data.

Also a small change I noticed and had sitting in my local tree to set
the previous RTP marker on a padding packet.

pkg/rtc/participant.go

@@ -2511,11 +2511,20 @@ func (p *ParticipantImpl) handleReceivedDataMessage(kind livekit.DataPacket_Kind
 		if payload.RpcRequest == nil {
 			return
 		}
-		p.pubLogger.Infow("received RPC request data packet", "method", payload.RpcRequest.Method, "rpc_request_id", payload.RpcRequest.Id)
+		p.pubLogger.Infow(
+			"received RPC request",
+			"method", payload.RpcRequest.Method,
+			"rpc_request_id", payload.RpcRequest.Id,
+			"destinationIdentities", dp.DestinationIdentities,
+		)
 	case *livekit.DataPacket_RpcResponse:
 		if payload.RpcResponse == nil {
 			return
 		}
+		p.pubLogger.Infow(
+			"received RPC response",
+			"rpc_request_id", payload.RpcResponse.RequestId,
+		)
 
 		rpcResponse := payload.RpcResponse
 		switch res := rpcResponse.Value.(type) {
@@ -2532,6 +2541,10 @@ func (p *ParticipantImpl) handleReceivedDataMessage(kind livekit.DataPacket_Kind
 		if payload.RpcAck == nil {
 			return
 		}
+		p.pubLogger.Infow(
+			"received RPC ack",
+			"rpc_request_id", payload.RpcAck.RequestId,
+		)
 
 		shouldForwardData = !p.handleIncomingRpcAck(payload.RpcAck.GetRequestId())
 	case *livekit.DataPacket_StreamHeader:

pkg/sfu/rtpmunger.go

@@ -328,6 +328,7 @@ func (r *RTPMunger) UpdateAndGetPaddingSnTs(
 	r.tsOffset -= extLastTS - r.extLastTS
 	r.extLastTS = extLastTS
 
+	r.secondLastMarker = r.lastMarker
 	if forceMarker {
 		r.lastMarker = true
 	}