feat(ext/node): ref/unref on workers (#22778)

Implements ref/unref on worker to fix part of #22629

ext/node/polyfills/worker_threads.ts

@@ -12,6 +12,7 @@ import { notImplemented } from "ext:deno_node/_utils.ts";
 import { EventEmitter, once } from "node:events";
 import { BroadcastChannel } from "ext:deno_broadcast_channel/01_broadcast_channel.js";
 import { MessageChannel, MessagePort } from "ext:deno_web/13_message_port.js";
+import { refWorker, unrefWorker } from "ext:runtime/11_workers.js";
 
 let environmentData = new Map();
 let threads = 0;
@@ -170,6 +171,14 @@ class _Worker extends EventEmitter {
     this.emit("exit", 0);
   }
 
+  ref() {
+    refWorker(this[kHandle]);
+  }
+
+  unref() {
+    unrefWorker(this[kHandle]);
+  }
+
   readonly getHeapSnapshot = () =>
     notImplemented("Worker.prototype.getHeapSnapshot");
   // fake performance

runtime/js/11_workers.js

@@ -1,6 +1,6 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
-import { primordials } from "ext:core/mod.js";
+import { core, primordials } from "ext:core/mod.js";
 import {
   op_create_worker,
   op_host_post_message,
@@ -14,6 +14,7 @@ const {
   ObjectPrototypeIsPrototypeOf,
   String,
   StringPrototypeStartsWith,
+  Symbol,
   SymbolFor,
   SymbolIterator,
   SymbolToStringTag,
@@ -72,9 +73,22 @@ function hostRecvMessage(id) {
   return op_host_recv_message(id);
 }
 
+const privateWorkerRef = Symbol();
+
+function refWorker(worker) {
+  worker[privateWorkerRef](true);
+}
+
+function unrefWorker(worker) {
+  worker[privateWorkerRef](false);
+}
+
 class Worker extends EventTarget {
   #id = 0;
   #name = "";
+  #refCount = 1;
+  #messagePromise = undefined;
+  #controlPromise = undefined;
 
   // "RUNNING" | "CLOSED" | "TERMINATED"
   // "TERMINATED" means that any controls or messages received will be
@@ -128,6 +142,30 @@ class Worker extends EventTarget {
     this.#pollMessages();
   }
 
+  [privateWorkerRef](ref) {
+    if (ref) {
+      this.#refCount++;
+    } else {
+      this.#refCount--;
+    }
+
+    if (!ref && this.#refCount == 0) {
+      if (this.#controlPromise) {
+        core.unrefOpPromise(this.#controlPromise);
+      }
+      if (this.#messagePromise) {
+        core.unrefOpPromise(this.#messagePromise);
+      }
+    } else if (ref && this.#refCount == 1) {
+      if (this.#controlPromise) {
+        core.refOpPromise(this.#controlPromise);
+      }
+      if (this.#messagePromise) {
+        core.refOpPromise(this.#messagePromise);
+      }
+    }
+  }
+
   #handleError(e) {
     const event = new ErrorEvent("error", {
       cancelable: true,
@@ -151,7 +189,11 @@ class Worker extends EventTarget {
 
   #pollControl = async () => {
     while (this.#status === "RUNNING") {
-      const { 0: type, 1: data } = await hostRecvCtrl(this.#id);
+      this.#controlPromise = hostRecvCtrl(this.#id);
+      if (this.#refCount < 1) {
+        core.unrefOpPromise(this.#controlPromise);
+      }
+      const { 0: type, 1: data } = await this.#controlPromise;
 
       // If terminate was called then we ignore all messages
       if (this.#status === "TERMINATED") {
@@ -182,7 +224,11 @@ class Worker extends EventTarget {
 
   #pollMessages = async () => {
     while (this.#status !== "TERMINATED") {
-      const data = await hostRecvMessage(this.#id);
+      this.#messagePromise = hostRecvMessage(this.#id);
+      if (this.#refCount < 1) {
+        core.unrefOpPromise(this.#messagePromise);
+      }
+      const data = await this.#messagePromise;
       if (this.#status === "TERMINATED" || data === null) {
         return;
       }
@@ -279,4 +325,4 @@ webidl.converters["WorkerType"] = webidl.createEnumConverter("WorkerType", [
   "module",
 ]);
 
-export { Worker };
+export { refWorker, unrefWorker, Worker };

tests/unit_node/worker_threads_test.ts

@@ -1,6 +1,11 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
-import { assert, assertEquals, assertObjectMatch } from "@std/assert/mod.ts";
+import {
+  assert,
+  assertEquals,
+  assertObjectMatch,
+  fail,
+} from "@std/assert/mod.ts";
 import { fromFileUrl, relative } from "@std/path/mod.ts";
 import * as workerThreads from "node:worker_threads";
 import { EventEmitter, once } from "node:events";
@@ -198,3 +203,18 @@ Deno.test({
     worker.terminate();
   },
 });
+
+Deno.test({
+  name: "[worker_threads] unref",
+  async fn() {
+    const timeout = setTimeout(() => fail("Test timed out"), 60_000);
+    const child = new Deno.Command(Deno.execPath(), {
+      args: [
+        "eval",
+        "import { Worker } from 'node:worker_threads'; new Worker('setTimeout(() => {}, 1_000_000)', {eval:true}).unref();",
+      ],
+    }).spawn();
+    await child.status;
+    clearTimeout(timeout);
+  },
+});