Fix: Publisher re-enable tracks after room connected in case of timout

src/state/CallViewModel/localMember/Publisher.test.ts

@@ -12,6 +12,8 @@ import {
   type LocalTrack,
   type LocalTrackPublication,
   ParticipantEvent,
+  PublishTrackError,
+  RoomEvent,
   Track,
 } from "livekit-client";
 import { BehaviorSubject } from "rxjs";
@@ -357,4 +359,50 @@ describe("Bug fix", () => {
       expect(track!.isMuted).toBe(true);
     }
   });
+
+  // When the connection is created, we call createAndSetupTracks immediately.
+  // But the livekit room connection is not yet established: `Connection#start` must
+  // first get the sfu config, and then connect to the livekit room.
+  // Livekit has support for this case by queuing publications until the room is connected,
+  // but this can time out if the room connection takes too long (15s)
+  it("Recovers failed publication due to room connection timeout", async () => {
+    // setLogLevel(`debug`);
+    const publisher = new Publisher(
+      scope,
+      connection,
+      mockMediaDevices({}),
+      muteStates,
+      constant({ supported: false, processor: undefined }),
+      logger,
+    );
+    audioEnabled$.next(true);
+    videoEnabled$.next(true);
+
+    const enableCameraAndMicrophoneSpy = vi.spyOn(
+      localParticipant,
+      "enableCameraAndMicrophone",
+    );
+
+    enableCameraAndMicrophoneSpy
+      .mockImplementationOnce(() => {
+        throw new PublishTrackError(
+          "publishing rejected as engine not connected within timeout",
+          408,
+        );
+      })
+      .mockImplementationOnce(async () => {
+        return Promise.resolve();
+      });
+
+    // call createAndSetupTracks which will attempt to publish and fail with the simulated timeout
+    await publisher.createAndSetupTracks();
+
+    // Now simulate the connection finally beeing connected
+    connection.livekitRoom.emit(RoomEvent.Connected);
+
+    await flushPromises();
+
+    // Should have called enableCameraAndMicrophone again to retry publication
+    expect(enableCameraAndMicrophoneSpy).toHaveBeenCalledTimes(2);
+  });
 });

src/state/CallViewModel/localMember/Publisher.ts

@@ -11,6 +11,7 @@ import {
   LocalVideoTrack,
   ParticipantEvent,
   type Room as LivekitRoom,
+  RoomEvent as LivekitRoomEvent,
   Track,
 } from "livekit-client";
 import {
@@ -89,6 +90,23 @@ export class Publisher {
       ParticipantEvent.LocalTrackPublished,
       this.onLocalTrackPublished.bind(this),
     );
+
+    this.connection.livekitRoom.once(LivekitRoomEvent.Connected, () => {
+      // When `createAndSetupTracks` is called before the connection is established,
+      // there is an internal timeout in livekit that could be triggered if it takes
+      // too long to connect.
+      // It is no-op if tracks are already created, so it is safe to call it again.
+      const audio = this.muteStates.audio.enabled$.value;
+      const video = this.muteStates.video.enabled$.value;
+      this.enableTracks(audio, video, this.connection.livekitRoom).catch(
+        (e) => {
+          this.logger.error(
+            "Failed to enable tracks after connection established",
+            e,
+          );
+        },
+      );
+    });
   }
 
   // LiveKit will publish the tracks as soon as they are created
@@ -157,18 +175,31 @@ export class Publisher {
     // We are using the `ParticipantEvent.LocalTrackPublished` to be notified
     // when tracks are actually published, and at that point
     // we can pause upstream if needed (depending on if startPublishing has been called).
-    if (audio && video) {
-      // Enable both at once in order to have a single permission prompt!
-      void lkRoom.localParticipant.enableCameraAndMicrophone();
-    } else if (audio) {
-      void lkRoom.localParticipant.setMicrophoneEnabled(true);
-    } else if (video) {
-      void lkRoom.localParticipant.setCameraEnabled(true);
-    }
+    this.enableTracks(audio, video, lkRoom).catch((e) => {
+      // If it is PublisherTrackError (408), i.e the publishing timed out,
+      // because it took too long to connet to the room, we are safe because
+      // we registered to the RoomEvent.Connected to create the tracks once connected.
+      this.logger.error("Failed to enable tracks", e);
+    });
 
     return Promise.resolve();
   }
 
+  private async enableTracks(
+    audio: boolean,
+    video: boolean,
+    lkRoom: LivekitRoom,
+  ): Promise<void> {
+    if (audio && video) {
+      // Enable both at once in order to have a single permission prompt!
+      await lkRoom.localParticipant.enableCameraAndMicrophone();
+    } else if (audio) {
+      await lkRoom.localParticipant.setMicrophoneEnabled(true);
+    } else if (video) {
+      await lkRoom.localParticipant.setCameraEnabled(true);
+    }
+  }
+
   private async pauseUpstreams(
     lkRoom: LivekitRoom,
     sources: Track.Source[],

src/utils/test.ts

@@ -176,6 +176,7 @@ export function withTestScheduler(
 interface EmitterMock<T> {
   on: (...args: unknown[]) => T;
   off: (...args: unknown[]) => T;
+  once: (...args: unknown[]) => T;
   addListener: (...args: unknown[]) => T;
   removeListener: (...args: unknown[]) => T;
   emit: (event: string | symbol, ...args: unknown[]) => boolean;
@@ -186,6 +187,7 @@ export function mockEmitter<T>(): EmitterMock<T> {
   return {
     on: ee.on.bind(ee) as unknown as (...args: unknown[]) => T,
     off: ee.off.bind(ee) as unknown as (...args: unknown[]) => T,
+    once: ee.once.bind(ee) as unknown as (...args: unknown[]) => T,
     addListener: ee.addListener.bind(ee) as unknown as (
       ...args: unknown[]
     ) => T,