add waitForSubscription

.changeset/shaggy-poets-grow.md

@@ -0,0 +1,5 @@
+---
+"@livekit/rtc-node": patch
+---
+
+add waitForSubscription

packages/livekit-rtc/src/room.ts

@@ -188,6 +188,7 @@ export class Room extends (EventEmitter as new () => TypedEmitter<RoomCallbacks>
       this.emit(RoomEvent.LocalTrackUnpublished, publication, this.localParticipant);
     } else if (ev.case == 'localTrackSubscribed') {
       const publication = this.localParticipant.trackPublications.get(ev.value.trackSid);
+      publication.resolveFirstSubscription();
       this.emit(RoomEvent.LocalTrackSubscribed, publication.track);
     } else if (ev.case == 'trackPublished') {
       const participant = this.remoteParticipants.get(ev.value.participantIdentity);

packages/livekit-rtc/src/track_publication.ts

@@ -69,8 +69,26 @@ export abstract class TrackPublication {
 }
 
 export class LocalTrackPublication extends TrackPublication {
+  private firstSubscription: Promise<void>;
+  private firstSubscriptionResolver: (() => void) | null = null;
+
   constructor(ownedInfo: OwnedTrackPublication) {
     super(ownedInfo);
+    this.firstSubscription = new Promise<void>((resolve) => {
+      this.firstSubscriptionResolver = resolve;
+    });
+  }
+
+  async waitForSubscription(): Promise<void> {
+    await this.firstSubscription;
+  }
+
+  /** @internal */
+  resolveFirstSubscription(): void {
+    if (this.firstSubscriptionResolver) {
+      this.firstSubscriptionResolver();
+      this.firstSubscriptionResolver = null;
+    }
   }
 }