From 455cf1743f70cb12025e36b3c4eb9a213fe77199 Mon Sep 17 00:00:00 2001
From: Satya Rohith <me@satyarohith.com>
Date: Mon, 29 Apr 2024 14:23:54 +0530
Subject: [PATCH] fix(ext/node): add support for MessagePort.removeListener/off
 (#23598)

Closes https://github.com/denoland/deno/issues/23564
---
 ext/node/polyfills/worker_threads.ts          | 24 +++++++++++++++++++
 ext/web/13_message_port.js                    |  5 ++++
 .../specs/node/worker_threads/__test__.jsonc  |  8 +++++++
 .../message_port_removelistener.mjs           |  9 +++++++
 .../message_port_removelistener.mjs.out       |  1 +
 5 files changed, 47 insertions(+)
 create mode 100644 tests/specs/node/worker_threads/__test__.jsonc
 create mode 100644 tests/specs/node/worker_threads/message_port_removelistener.mjs
 create mode 100644 tests/specs/node/worker_threads/message_port_removelistener.mjs.out

diff --git a/ext/node/polyfills/worker_threads.ts b/ext/node/polyfills/worker_threads.ts
index 8f531368ae..e88e6368b5 100644
--- a/ext/node/polyfills/worker_threads.ts
+++ b/ext/node/polyfills/worker_threads.ts
@@ -473,6 +473,12 @@ class NodeMessageChannel {
   }
 }
 
+const listeners = new SafeWeakMap<
+  // deno-lint-ignore no-explicit-any
+  (...args: any[]) => void,
+  // deno-lint-ignore no-explicit-any
+  (ev: any) => any
+>();
 function webMessagePortToNodeMessagePort(port: MessagePort) {
   port.on = port.addListener = function (this: MessagePort, name, listener) {
     // deno-lint-ignore no-explicit-any
@@ -486,6 +492,24 @@ function webMessagePortToNodeMessagePort(port: MessagePort) {
     } else {
       throw new Error(`Unknown event: "${name}"`);
     }
+    listeners.set(listener, _listener);
+    return this;
+  };
+  port.off = port.removeListener = function (
+    this: MessagePort,
+    name,
+    listener,
+  ) {
+    if (name == "message") {
+      port.removeEventListener("message", listeners.get(listener)!);
+    } else if (name == "messageerror") {
+      port.removeEventListener("messageerror", listeners.get(listener)!);
+    } else if (name == "close") {
+      port.removeEventListener("close", listeners.get(listener)!);
+    } else {
+      throw new Error(`Unknown event: "${name}"`);
+    }
+    listeners.delete(listener);
     return this;
   };
   port[nodeWorkerThreadCloseCb] = () => {
diff --git a/ext/web/13_message_port.js b/ext/web/13_message_port.js
index 4e4184f2a3..93145e8f74 100644
--- a/ext/web/13_message_port.js
+++ b/ext/web/13_message_port.js
@@ -190,6 +190,11 @@ class MessagePort extends EventTarget {
       this[_enabled] = true;
       while (true) {
         if (this[_id] === null) break;
+        // Exit if no message event listeners are present in Node compat mode.
+        if (
+          typeof this[nodeWorkerThreadCloseCb] == "function" &&
+          messageEventListenerCount === 0
+        ) break;
         let data;
         try {
           data = await op_message_port_recv_message(
diff --git a/tests/specs/node/worker_threads/__test__.jsonc b/tests/specs/node/worker_threads/__test__.jsonc
new file mode 100644
index 0000000000..adcb9a85d6
--- /dev/null
+++ b/tests/specs/node/worker_threads/__test__.jsonc
@@ -0,0 +1,8 @@
+{
+  "steps": [{
+    "args": "run message_port_removelistener.mjs",
+    "output": "message_port_removelistener.mjs.out",
+    // Note: successful exit asserts that the test passed
+    "exitCode": 0
+  }]
+}
diff --git a/tests/specs/node/worker_threads/message_port_removelistener.mjs b/tests/specs/node/worker_threads/message_port_removelistener.mjs
new file mode 100644
index 0000000000..e0cac6ce93
--- /dev/null
+++ b/tests/specs/node/worker_threads/message_port_removelistener.mjs
@@ -0,0 +1,9 @@
+import { MessageChannel } from "node:worker_threads";
+
+const { port1, port2 } = new MessageChannel();
+const listener = (message) => {
+  console.log(message);
+  port1.off("message", listener);
+};
+port1.on("message", listener);
+port2.postMessage("Hello World!");
diff --git a/tests/specs/node/worker_threads/message_port_removelistener.mjs.out b/tests/specs/node/worker_threads/message_port_removelistener.mjs.out
new file mode 100644
index 0000000000..980a0d5f19
--- /dev/null
+++ b/tests/specs/node/worker_threads/message_port_removelistener.mjs.out
@@ -0,0 +1 @@
+Hello World!