From 2fe8a79ea0f439c46a641f9ec5b76017be21f39d Mon Sep 17 00:00:00 2001
From: Darshan Sen <raisinten@gmail.com>
Date: Wed, 20 Apr 2022 04:57:14 +0530
Subject: [PATCH] worker: add hasRef() to the handle object

This should help projects like
https://github.com/mafintosh/why-is-node-running and
https://github.com/facebook/jest to detect if Worker instances are
keeping the event loop active correctly.

Fixes: https://github.com/nodejs/node/issues/42091
Refs: https://github.com/mafintosh/why-is-node-running/issues/59
Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/42756
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
---
 src/node_worker.cc                  |  8 +++++++
 src/node_worker.h                   |  1 +
 test/parallel/test-worker-hasref.js | 33 +++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)
 create mode 100644 test/parallel/test-worker-hasref.js

diff --git a/src/node_worker.cc b/src/node_worker.cc
index 752fc48141f5e1..02420cd6327047 100644
--- a/src/node_worker.cc
+++ b/src/node_worker.cc
@@ -676,6 +676,12 @@ void Worker::Ref(const FunctionCallbackInfo<Value>& args) {
   }
 }
 
+void Worker::HasRef(const FunctionCallbackInfo<Value>& args) {
+  Worker* w;
+  ASSIGN_OR_RETURN_UNWRAP(&w, args.This());
+  args.GetReturnValue().Set(w->has_ref_);
+}
+
 void Worker::Unref(const FunctionCallbackInfo<Value>& args) {
   Worker* w;
   ASSIGN_OR_RETURN_UNWRAP(&w, args.This());
@@ -838,6 +844,7 @@ void InitWorker(Local<Object> target,
 
     env->SetProtoMethod(w, "startThread", Worker::StartThread);
     env->SetProtoMethod(w, "stopThread", Worker::StopThread);
+    env->SetProtoMethod(w, "hasRef", Worker::HasRef);
     env->SetProtoMethod(w, "ref", Worker::Ref);
     env->SetProtoMethod(w, "unref", Worker::Unref);
     env->SetProtoMethod(w, "getResourceLimits", Worker::GetResourceLimits);
@@ -901,6 +908,7 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(Worker::New);
   registry->Register(Worker::StartThread);
   registry->Register(Worker::StopThread);
+  registry->Register(Worker::HasRef);
   registry->Register(Worker::Ref);
   registry->Register(Worker::Unref);
   registry->Register(Worker::GetResourceLimits);
diff --git a/src/node_worker.h b/src/node_worker.h
index 077d2b8390e6f8..cc3d24188ef735 100644
--- a/src/node_worker.h
+++ b/src/node_worker.h
@@ -60,6 +60,7 @@ class Worker : public AsyncWrap {
   static void SetEnvVars(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void StartThread(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void StopThread(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void HasRef(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Ref(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Unref(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void GetResourceLimits(
diff --git a/test/parallel/test-worker-hasref.js b/test/parallel/test-worker-hasref.js
new file mode 100644
index 00000000000000..51593b14725f5b
--- /dev/null
+++ b/test/parallel/test-worker-hasref.js
@@ -0,0 +1,33 @@
+'use strict';
+const common = require('../common');
+
+const { Worker } = require('worker_threads');
+const { createHook } = require('async_hooks');
+const { strictEqual } = require('assert');
+
+let handle;
+
+createHook({
+  init(asyncId, type, triggerAsyncId, resource) {
+    if (type === 'WORKER') {
+      handle = resource;
+      this.disable();
+    }
+  }
+}).enable();
+
+const w = new Worker('', { eval: true });
+
+strictEqual(handle.hasRef(), true);
+w.unref();
+strictEqual(handle.hasRef(), false);
+w.ref();
+strictEqual(handle.hasRef(), true);
+
+w.on('exit', common.mustCall((exitCode) => {
+  strictEqual(exitCode, 0);
+  strictEqual(handle.hasRef(), true);
+  setTimeout(common.mustCall(() => {
+    strictEqual(handle.hasRef(), undefined);
+  }), 0);
+}));