Monaco editor webworker fixes (microsoft#254951)

Author: hediet

src/vs/base/browser/webWorkerFactory.ts

@@ -129,13 +129,14 @@ class WebWorker extends Disposable implements IWebWorker {
 	private readonly _onError = this._register(new Emitter<any>());
 	public readonly onError = this._onError.event;
 
-	constructor(descriptorOrWorker: IWebWorkerDescriptor | Worker) {
+	constructor(descriptorOrWorker: IWebWorkerDescriptor | Worker | Promise<Worker>) {
 		super();
 		this.id = ++WebWorker.LAST_WORKER_ID;
 		const workerOrPromise = (
 			descriptorOrWorker instanceof Worker
-				? descriptorOrWorker
-				: getWorker(descriptorOrWorker, this.id)
+				? descriptorOrWorker :
+				'then' in descriptorOrWorker ? descriptorOrWorker
+					: getWorker(descriptorOrWorker, this.id)
 		);
 		if (isPromiseLike(workerOrPromise)) {
 			this.worker = workerOrPromise;
@@ -197,8 +198,8 @@ export class WebWorkerDescriptor implements IWebWorkerDescriptor {
 }
 
 export function createWebWorker<T extends object>(esmModuleLocation: URI, label: string | undefined): IWebWorkerClient<T>;
-export function createWebWorker<T extends object>(workerDescriptor: IWebWorkerDescriptor | Worker): IWebWorkerClient<T>;
-export function createWebWorker<T extends object>(arg0: URI | IWebWorkerDescriptor | Worker, arg1?: string | undefined): IWebWorkerClient<T> {
+export function createWebWorker<T extends object>(workerDescriptor: IWebWorkerDescriptor | Worker | Promise<Worker>): IWebWorkerClient<T>;
+export function createWebWorker<T extends object>(arg0: URI | IWebWorkerDescriptor | Worker | Promise<Worker>, arg1?: string | undefined): IWebWorkerClient<T> {
 	const workerDescriptorOrWorker = (URI.isUri(arg0) ? new WebWorkerDescriptor(arg0, arg1) : arg0);
 	return new WebWorkerClient<T>(new WebWorker(workerDescriptorOrWorker));
 }

src/vs/editor/browser/services/editorWorkerService.ts

@@ -427,7 +427,7 @@ export class EditorWorkerClient extends Disposable implements IEditorWorkerClien
 	private _disposed = false;
 
 	constructor(
-		private readonly _workerDescriptorOrWorker: IWebWorkerDescriptor | Worker,
+		private readonly _workerDescriptorOrWorker: IWebWorkerDescriptor | Worker | Promise<Worker>,
 		keepIdleModels: boolean,
 		@IModelService modelService: IModelService,
 	) {

src/vs/editor/common/services/editorWebWorker.ts

@@ -38,7 +38,7 @@ export interface IMirrorModel extends IMirrorTextModel {
 	getValue(): string;
 }
 
-export interface IWorkerContext<H = undefined> {
+export interface IWorkerContext<H = {}> {
 	/**
 	 * A proxy to the main thread host object.
 	 */

src/vs/editor/editor.worker.start.ts

@@ -12,24 +12,37 @@ import { EditorWorkerHost } from './common/services/editorWorkerHost.js';
  * @skipMangle
  * @internal
  */
-export function start<THost extends object, TClient extends object>(client: TClient): IWorkerContext<THost> {
-	const webWorkerServer = initialize(() => new EditorWorker(client));
-	const editorWorkerHost = EditorWorkerHost.getChannel(webWorkerServer);
-	const host = new Proxy({}, {
-		get(target, prop, receiver) {
-			if (typeof prop !== 'string') {
-				throw new Error(`Not supported`);
+export function start<THost extends object, TClient extends object>(createClient: (ctx: IWorkerContext<THost>) => TClient): TClient {
+	let client: TClient | undefined;
+	const webWorkerServer = initialize((workerServer) => {
+		const editorWorkerHost = EditorWorkerHost.getChannel(workerServer);
+
+		const host = new Proxy({}, {
+			get(target, prop, receiver) {
+				if (prop === 'then') {
+					// Don't forward the call when the proxy is returned in an async function and the runtime tries to .then it.
+					return undefined;
+				}
+				if (typeof prop !== 'string') {
+					throw new Error(`Not supported`);
+				}
+				return (...args: unknown[]) => {
+					return editorWorkerHost.$fhr(prop, args);
+				};
+			}
+		});
+
+		const ctx: IWorkerContext<THost> = {
+			host: host as THost,
+			getMirrorModels: () => {
+				return webWorkerServer.requestHandler.getModels();
 			}
-			return (...args: unknown[]) => {
-				return editorWorkerHost.$fhr(prop, args);
-			};
-		}
+		};
+
+		client = createClient(ctx);
+
+		return new EditorWorker(client);
 	});
 
-	return {
-		host: host as THost,
-		getMirrorModels: () => {
-			return webWorkerServer.requestHandler.getModels();
-		}
-	};
+	return client!;
 }

src/vs/editor/standalone/browser/standaloneWebWorker.ts

@@ -38,7 +38,7 @@ export interface IInternalWebWorkerOptions {
 	/**
 	 * The worker.
 	 */
-	worker: Worker;
+	worker: Worker | Promise<Worker>;
 	/**
 	 * An object that can be used by the web worker to make calls back to the main thread.
 	 */
@@ -61,6 +61,10 @@ class MonacoWebWorkerImpl<T extends object> extends EditorWorkerClient implement
 		this._foreignProxy = this._getProxy().then(proxy => {
 			return new Proxy({}, {
 				get(target, prop, receiver) {
+					if (prop === 'then') {
+						// Don't forward the call when the proxy is returned in an async function and the runtime tries to .then it.
+						return undefined;
+					}
 					if (typeof prop !== 'string') {
 						throw new Error(`Not supported`);
 					}

src/vs/monaco.d.ts

@@ -1223,7 +1223,7 @@ declare namespace monaco.editor {
 		/**
 		 * The worker.
 		 */
-		worker: Worker;
+		worker: Worker | Promise<Worker>;
 		/**
 		 * An object that can be used by the web worker to make calls back to the main thread.
 		 */
@@ -8542,7 +8542,7 @@ declare namespace monaco.worker {
 		getValue(): string;
 	}
 
-	export interface IWorkerContext<H = undefined> {
+	export interface IWorkerContext<H = {}> {
 		/**
 		 * A proxy to the main thread host object.
 		 */