Defer publishing until signal is connected (#1465)

lukasIO · web-flow · commit 1a5a96638f42 · 2025-04-08T20:54:15.000+02:00
diff --git a/.changeset/eight-horses-raise.md b/.changeset/eight-horses-raise.md
@@ -0,0 +1,5 @@
+---
+"livekit-client": minor
+---
+
+Defer publishing until signal is connected
diff --git a/examples/demo/demo.ts b/examples/demo/demo.ts
@@ -235,11 +235,6 @@ const appActions = {
         appendLog(`signal connection established in ${signalConnectionTime}ms`);
         // speed up publishing by starting to publish before it's fully connected
         // publishing is accepted as soon as signal connection has established
-        if (shouldPublish) {
-          await room.localParticipant.enableCameraAndMicrophone();
-          appendLog(`tracks published in ${Date.now() - startTime}ms`);
-          updateButtonsForPublishState();
-        }
       })
       .on(RoomEvent.ParticipantEncryptionStatusChanged, () => {
         updateButtonsForPublishState();
@@ -353,8 +348,19 @@ const appActions = {
       if ((<HTMLInputElement>$('e2ee')).checked) {
         await room.setE2EEEnabled(true);
       }
-
-      await room.connect(url, token, connectOptions);
+      const publishPromise = new Promise<void>(async (resolve, reject) => {
+        try {
+          if (shouldPublish) {
+            await room.localParticipant.enableCameraAndMicrophone();
+            appendLog(`tracks published in ${Date.now() - startTime}ms`);
+            updateButtonsForPublishState();
+          }
+          resolve();
+        } catch (error) {
+          reject(error);
+        }
+      });
+      await Promise.all([room.connect(url, token, connectOptions), publishPromise]);
       const elapsed = Date.now() - startTime;
       appendLog(
         `successfully connected to ${room.name} in ${Math.round(elapsed)}ms`,
diff --git a/src/room/RTCEngine.ts b/src/room/RTCEngine.ts
@@ -248,6 +248,10 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
       }
 
       this.clientConfiguration = joinResponse.clientConfiguration;
+      // emit signal connected event after a short delay to allow for join response to be processed on room
+      setTimeout(() => {
+        this.emit(EngineEvent.SignalConnected);
+      }, 10);
       return joinResponse;
     } catch (e) {
       if (e instanceof ConnectionError) {
@@ -1500,6 +1504,7 @@ export type EngineEventCallbacks = {
   remoteMute: (trackSid: string, muted: boolean) => void;
   offline: () => void;
   signalRequestResponse: (response: RequestResponse) => void;
+  signalConnected: () => void;
 };
 
 function supportOptionalDatachannel(protocol: number | undefined): boolean {
diff --git a/src/room/events.ts b/src/room/events.ts
@@ -562,6 +562,7 @@ export enum EngineEvent {
   LocalTrackSubscribed = 'localTrackSubscribed',
   Offline = 'offline',
   SignalRequestResponse = 'signalRequestResponse',
+  SignalConnected = 'signalConnected',
 }
 
 export enum TrackEvent {
diff --git a/src/room/participant/LocalParticipant.ts b/src/room/participant/LocalParticipant.ts
@@ -28,6 +28,7 @@ import {
   UserPacket,
   protoInt64,
 } from '@livekit/protocol';
+import { SignalConnectionState } from '../../api/SignalClient';
 import type { InternalRoomOptions } from '../../options';
 import { PCTransportState } from '../PCTransportManager';
 import type RTCEngine from '../RTCEngine';
@@ -866,7 +867,37 @@ export default class LocalParticipant extends Participant {
     if (opts.source) {
       track.source = opts.source;
     }
-    const publishPromise = this.publish(track, opts, isStereo);
+    const publishPromise = new Promise<LocalTrackPublication>(async (resolve, reject) => {
+      try {
+        if (this.engine.client.currentState !== SignalConnectionState.CONNECTED) {
+          this.log.debug('deferring track publication until signal is connected', {
+            ...this.logContext,
+            track: getLogContextFromTrack(track),
+          });
+          const onSignalConnected = async () => {
+            return this.publish(track, opts, isStereo).then(resolve).catch(reject);
+          };
+          setTimeout(() => {
+            this.engine.off(EngineEvent.SignalConnected, onSignalConnected);
+            reject(
+              new PublishTrackError(
+                'publishing rejected as engine not connected within timeout',
+                408,
+              ),
+            );
+          }, 15_000);
+          this.engine.once(EngineEvent.SignalConnected, onSignalConnected);
+          this.engine.on(EngineEvent.Closing, () => {
+            this.engine.off(EngineEvent.SignalConnected, onSignalConnected);
+            reject(new PublishTrackError('publishing rejected as engine closed', 499));
+          });
+        } else {
+          return await this.publish(track, opts, isStereo);
+        }
+      } catch (e) {
+        reject(e);
+      }
+    });
     this.pendingPublishPromises.set(track, publishPromise);
     try {
       const publication = await publishPromise;

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"livekit-client": minor
 +---
++
 +Defer publishing until signal is connected
Original file line number	Diff line number	Diff line change
`@@ -562,6 +562,7 @@ export enum EngineEvent {`
`562`	`562`	`LocalTrackSubscribed = 'localTrackSubscribed',`
`563`	`563`	`Offline = 'offline',`
`564`	`564`	`SignalRequestResponse = 'signalRequestResponse',`
	`565`	`+ SignalConnected = 'signalConnected',`
`565`	`566`	`}`
`566`	`567`
`567`	`568`	`export enum TrackEvent {`