worker: make transfer list behave like web MessagePort

Allow generic iterables as transfer list arguments, as well
as an options object with a `transfer` option, for web compatibility.

PR-URL: https://github.com/nodejs/node/pull/29319
Refs: https://github.com/nodejs/node/pull/28033#discussion_r289964991
Reviewed-By: James M Snell <jasnell@gmail.com>

2 files changed, 87 insertions, 2 deletions

diff --git a/test/parallel/test-worker-message-port-terminate-transfer-list.js b/test/parallel/test-worker-message-port-terminate-transfer-list.js
new file mode 100644
index 0000000000..a066405d9d
--- /dev/null
+++ b/test/parallel/test-worker-message-port-terminate-transfer-list.js
@@ -0,0 +1,26 @@
+'use strict';
+const common = require('../common');
+
+const { parentPort, MessageChannel, Worker } = require('worker_threads');
+
+// Do not use isMainThread so that this test itself can be run inside a Worker.
+if (!process.env.HAS_STARTED_WORKER) {
+  process.env.HAS_STARTED_WORKER = 1;
+  const w = new Worker(__filename);
+  w.once('message', common.mustCall(() => {
+    w.once('message', common.mustNotCall());
+    setTimeout(() => w.terminate(), 100);
+  }));
+} else {
+  const { port1 } = new MessageChannel();
+
+  parentPort.postMessage('ready');
+
+  // Make sure we don’t end up running JS after the infinite loop is broken.
+  port1.postMessage({}, {
+    transfer: (function*() { while (true); })()
+  });
+
+  parentPort.postMessage('UNREACHABLE');
+  process.kill(process.pid, 'SIGINT');
+}
diff --git a/test/parallel/test-worker-message-port.js b/test/parallel/test-worker-message-port.js
index d1c58216fd..d128dc7edb 100644
--- a/test/parallel/test-worker-message-port.js
+++ b/test/parallel/test-worker-message-port.js
@@ -72,22 +72,81 @@ const { MessageChannel, MessagePort } = require('worker_threads');
 
 {
   const { port1, port2 } = new MessageChannel();
-  port2.on('message', common.mustCall(4));
+  port2.on('message', common.mustCall(6));
   port1.postMessage(1, null);
   port1.postMessage(2, undefined);
   port1.postMessage(3, []);
   port1.postMessage(4, {});
+  port1.postMessage(5, { transfer: undefined });
+  port1.postMessage(6, { transfer: [] });
 
   const err = {
     constructor: TypeError,
     code: 'ERR_INVALID_ARG_TYPE',
-    message: 'Optional transferList argument must be an array'
+    message: 'Optional transferList argument must be an iterable'
   };
 
   assert.throws(() => port1.postMessage(5, 0), err);
   assert.throws(() => port1.postMessage(5, false), err);
   assert.throws(() => port1.postMessage(5, 'X'), err);
   assert.throws(() => port1.postMessage(5, Symbol('X')), err);
+
+  const err2 = {
+    constructor: TypeError,
+    code: 'ERR_INVALID_ARG_TYPE',
+    message: 'Optional options.transfer argument must be an iterable'
+  };
+
+  assert.throws(() => port1.postMessage(5, { transfer: null }), err2);
+  assert.throws(() => port1.postMessage(5, { transfer: 0 }), err2);
+  assert.throws(() => port1.postMessage(5, { transfer: false }), err2);
+  assert.throws(() => port1.postMessage(5, { transfer: {} }), err2);
+  assert.throws(() => port1.postMessage(5, {
+    transfer: { [Symbol.iterator]() { return {}; } }
+  }), err2);
+  assert.throws(() => port1.postMessage(5, {
+    transfer: { [Symbol.iterator]() { return { next: 42 }; } }
+  }), err2);
+  assert.throws(() => port1.postMessage(5, {
+    transfer: { [Symbol.iterator]() { return { next: null }; } }
+  }), err2);
+  port1.close();
+}
+
+{
+  // Make sure these ArrayBuffers end up detached, i.e. are actually being
+  // transferred because the transfer list provides them.
+  const { port1, port2 } = new MessageChannel();
+  port2.on('message', common.mustCall((msg) => {
+    assert.strictEqual(msg.ab.byteLength, 10);
+  }, 4));
+
+  {
+    const ab = new ArrayBuffer(10);
+    port1.postMessage({ ab }, [ ab ]);
+    assert.strictEqual(ab.byteLength, 0);
+  }
+
+  {
+    const ab = new ArrayBuffer(10);
+    port1.postMessage({ ab }, { transfer: [ ab ] });
+    assert.strictEqual(ab.byteLength, 0);
+  }
+
+  {
+    const ab = new ArrayBuffer(10);
+    port1.postMessage({ ab }, (function*() { yield ab; })());
+    assert.strictEqual(ab.byteLength, 0);
+  }
+
+  {
+    const ab = new ArrayBuffer(10);
+    port1.postMessage({ ab }, {
+      transfer: (function*() { yield ab; })()
+    });
+    assert.strictEqual(ab.byteLength, 0);
+  }
+
   port1.close();
 }