add a ping message to make sure worker port is alive

src/connection.ts

@@ -3,7 +3,7 @@ import { BareHeaders, TransferrableResponse } from "./baretypes";
 type SWClient = { postMessage: typeof MessagePort.prototype.postMessage };
 
 export type WorkerMessage = {
-	type: "fetch" | "websocket" | "set" | "get",
+	type: "fetch" | "websocket" | "set" | "get" | "ping",
 	fetch?: {
 		remote: string,
 		method: string,
@@ -26,7 +26,7 @@ export type WorkerRequest = {
 }
 
 export type WorkerResponse = {
-	type: "fetch" | "websocket" | "set" | "get" | "error",
+	type: "fetch" | "websocket" | "set" | "get" | "pong" | "error",
 	fetch?: TransferrableResponse,
 	name?: string,
 	error?: Error,
@@ -59,8 +59,9 @@ function tryGetPort(client: SWClient): Promise<MessagePort> {
 	});
 }
 
-function createPort(path: string, channel: BroadcastChannel): MessagePort {
+function createPort(path: string, channel: BroadcastChannel, registerHandlers: boolean): MessagePort {
 	const worker = new SharedWorker(path, "bare-mux-worker");
+	if (registerHandlers) {
 		// uv removes navigator.serviceWorker so this errors
 		if (navigator.serviceWorker) {
 			navigator.serviceWorker.addEventListener("message", event => {
@@ -77,15 +78,21 @@ function createPort(path: string, channel: BroadcastChannel): MessagePort {
 				channel.postMessage(<BroadcastMessage>{ type: "path", path: path });
 			}
 		};
+	}
 	return worker.port;
 }
 
 export class WorkerConnection {
 	channel: BroadcastChannel;
 	port: MessagePort | Promise<MessagePort>;
+	workerPath: string;
 
 	constructor(workerPath?: string) {
 		this.channel = new BroadcastChannel("bare-mux");
+		this.createChannel(workerPath, true);
+	}
+
+	createChannel(workerPath?: string, inInit?: boolean) {
 		// @ts-expect-error
 		if (self.clients) {
 			// running in a ServiceWorker
@@ -101,14 +108,14 @@ export class WorkerConnection {
 			// create the SharedWorker and help other bare-mux clients get the workerPath
 
 			if (!workerPath.startsWith("/") && !workerPath.includes("://")) throw new Error("Invalid URL. Must be absolute or start at the root.");
-			this.port = createPort(workerPath, this.channel);
+			this.port = createPort(workerPath, this.channel, inInit);
 		} else if (SharedWorker) {
 			// running in a window, was not passed a workerPath
 			// ask other bare-mux clients for the workerPath
 			this.port = new Promise(resolve => {
 				this.channel.onmessage = (event: MessageEvent) => {
 					if (event.data.type === "path") {
-						resolve(createPort(event.data.path, this.channel));
+						resolve(createPort(event.data.path, this.channel, inInit));
 					}
 				}
 				this.channel.postMessage(<BroadcastMessage>{ type: "getPath" });
@@ -121,12 +128,29 @@ export class WorkerConnection {
 
 	async sendMessage(message: WorkerMessage, transferable?: Transferable[]): Promise<WorkerResponse> {
 		if (this.port instanceof Promise) this.port = await this.port;
-		let channel = new MessageChannel();
-		let toTransfer: Transferable[] = [channel.port2, ...(transferable || [])];
 
-		this.port.postMessage(<WorkerRequest>{ message: message, port: channel.port2 }, toTransfer);
+		const pingChannel = new MessageChannel();
+		const pingPromise: Promise<void> = new Promise((resolve, reject) => {
+			pingChannel.port1.onmessage = event => {
+				if (event.data.type === "pong") {
+					resolve();
+				}
+			};
+			setTimeout(reject, 1500);
+		});
+		this.port.postMessage(<WorkerRequest>{ message: { type: "ping" }, port: pingChannel.port2 }, [pingChannel.port2]);
+		try {
+			await pingPromise;
+		} catch {
+			console.warn("Failed to get a ping response from the worker within 1.5s. Assuming port is dead.");
+			this.createChannel();
+			return await this.sendMessage(message, transferable);
+		}
 
-		return await new Promise((resolve, reject) => {
+		const channel = new MessageChannel();
+		const toTransfer: Transferable[] = [channel.port2, ...(transferable || [])];
+
+		const promise: Promise<WorkerResponse> = new Promise((resolve, reject) => {
 			channel.port1.onmessage = event => {
 				const message = event.data;
 				if (message.type === "error") {
@@ -136,5 +160,8 @@ export class WorkerConnection {
 				}
 			}
 		});
+		this.port.postMessage(<WorkerRequest>{ message: message, port: channel.port2 }, toTransfer);
+
+		return await promise;
 	}
 }

src/worker.ts

@@ -18,8 +18,9 @@ function handleConnection(port: MessagePort) {
 	port.onmessage = async (event: MessageEvent) => {
 		const port = event.data.port;
 		const message: WorkerMessage = event.data.message;
-
-		if (message.type === "set") {
+		if (message.type === "ping") {
+			port.postMessage(<WorkerResponse>{ type: "pong" });
+		} else if (message.type === "set") {
 			try {
 				const AsyncFunction = (async function() { }).constructor;
 
@@ -32,6 +33,7 @@ function handleConnection(port: MessagePort) {
 
 				port.postMessage(<WorkerResponse>{ type: "set" });
 			} catch (err) {
+				console.error(err);
 				port.postMessage(<WorkerResponse>{ type: "error", error: err });
 			}
 		} else if (message.type === "get") {
@@ -55,6 +57,7 @@ function handleConnection(port: MessagePort) {
 					port.postMessage(<WorkerResponse>{ type: "fetch", fetch: resp });
 				}
 			} catch (err) {
+				console.error(err);
 				port.postMessage(<WorkerResponse>{ type: "error", error: err });
 			}
 		} else if (message.type === "websocket") {
@@ -98,6 +101,7 @@ function handleConnection(port: MessagePort) {
 
 				port.postMessage(<WorkerResponse>{ type: "websocket" });
 			} catch (err) {
+				console.error(err);
 				port.postMessage(<WorkerResponse>{ type: "error", error: err });
 			}
 		}