Skip to content

Commit

Permalink
worker: add hasRef() to MessagePort
Browse files Browse the repository at this point in the history
Since we were removing the hasRef() method before exposing the
MessagePort object, the only way of knowing if the handle was keeping
the event loop active was to parse the string returned by
util.inspect(port), which is inconvenient and inconsistent with most of
the other async resources. So this change stops removing hasRef() from
the MessagePort prototype. The reason why this is also being documented
is that while reporting active resources, async_hooks returns the same
MessagePort object as the one that is accessible by users.

Refs: #42091 (comment)
Signed-off-by: Darshan Sen <[email protected]>

PR-URL: #42849
Reviewed-By: Anna Henningsen <[email protected]>
  • Loading branch information
RaisinTen authored and targos committed May 2, 2022
1 parent 1e7479d commit bf9240a
Show file tree
Hide file tree
Showing 5 changed files with 120 additions and 3 deletions.
12 changes: 12 additions & 0 deletions doc/api/worker_threads.md
Original file line number Diff line number Diff line change
Expand Up @@ -763,6 +763,18 @@ port2.postMessage(new URL('https://example.org'));
// Prints: { }
```

### `port.hasRef()`

<!-- YAML
added: REPLACEME
-->

> Stability: 1 - Experimental
* Returns: {boolean}

If true, the `MessagePort` object will keep the Node.js event loop active.

### `port.ref()`

<!-- YAML
Expand Down
5 changes: 4 additions & 1 deletion lib/internal/worker/io.js
Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,7 @@ const messageTypes = {
// We have to mess with the MessagePort prototype a bit, so that a) we can make
// it inherit from NodeEventTarget, even though it is a C++ class, and b) we do
// not provide methods that are not present in the Browser and not documented
// on our side (e.g. hasRef).
// on our side (e.g. stopMessagePort).
// Save a copy of the original set of methods as a shallow clone.
const MessagePortPrototype = ObjectCreate(
ObjectGetPrototypeOf(MessagePort.prototype),
Expand All @@ -103,6 +103,9 @@ ObjectSetPrototypeOf(MessagePort.prototype, NodeEventTarget.prototype);
// changing the prototype of MessagePort.prototype implicitly removed them.
MessagePort.prototype.ref = MessagePortPrototype.ref;
MessagePort.prototype.unref = MessagePortPrototype.unref;
MessagePort.prototype.hasRef = function() {
return !!FunctionPrototypeCall(MessagePortPrototype.hasRef, this);
};

function validateMessagePort(port, name) {
if (!checkMessagePort(port))
Expand Down
57 changes: 57 additions & 0 deletions test/parallel/test-messageport-hasref.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,57 @@
'use strict';
const common = require('../common');

const { MessageChannel } = require('worker_threads');
const { createHook } = require('async_hooks');
const { strictEqual } = require('assert');

const handles = [];

createHook({
init(asyncId, type, triggerAsyncId, resource) {
if (type === 'MESSAGEPORT') {
handles.push(resource);
}
}
}).enable();

const { port1, port2 } = new MessageChannel();
strictEqual(handles[0], port1);
strictEqual(handles[1], port2);

strictEqual(handles[0].hasRef(), false);
strictEqual(handles[1].hasRef(), false);

port1.unref();
strictEqual(handles[0].hasRef(), false);

port1.ref();
strictEqual(handles[0].hasRef(), true);

port1.unref();
strictEqual(handles[0].hasRef(), false);

port1.on('message', () => {});
strictEqual(handles[0].hasRef(), true);

port2.unref();
strictEqual(handles[1].hasRef(), false);

port2.ref();
strictEqual(handles[1].hasRef(), true);

port2.unref();
strictEqual(handles[1].hasRef(), false);

port2.on('message', () => {});
strictEqual(handles[0].hasRef(), true);

port1.on('close', common.mustCall(() => {
strictEqual(handles[0].hasRef(), false);
strictEqual(handles[1].hasRef(), false);
}));

port2.close();

strictEqual(handles[0].hasRef(), true);
strictEqual(handles[1].hasRef(), true);
4 changes: 2 additions & 2 deletions test/parallel/test-worker-message-port.js
Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,7 @@ const { MessageChannel, MessagePort } = require('worker_threads');
assert.deepStrictEqual(
Object.getOwnPropertyNames(MessagePort.prototype).sort(),
[
'close', 'constructor', 'onmessage', 'onmessageerror', 'postMessage',
'ref', 'start', 'unref',
'close', 'constructor', 'hasRef', 'onmessage', 'onmessageerror',
'postMessage', 'ref', 'start', 'unref',
]);
}
45 changes: 45 additions & 0 deletions test/parallel/test-worker-messageport-hasref.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
'use strict';
const common = require('../common');

const { Worker } = require('worker_threads');
const { createHook } = require('async_hooks');
const { deepStrictEqual, strictEqual } = require('assert');

const m = new Map();
createHook({
init(asyncId, type, triggerAsyncId, resource) {
if (['WORKER', 'MESSAGEPORT'].includes(type)) {
m.set(asyncId, { type, resource });
}
},
destroy(asyncId) {
m.delete(asyncId);
}
}).enable();

function getActiveWorkerAndMessagePortTypes() {
const activeWorkerAndMessagePortTypes = [];
for (const asyncId of m.keys()) {
const { type, resource } = m.get(asyncId);
// Same logic as https://github.com/mafintosh/why-is-node-running/blob/24fb4c878753390a05d00959e6173d0d3c31fddd/index.js#L31-L32.
if (typeof resource.hasRef !== 'function' || resource.hasRef() === true) {
activeWorkerAndMessagePortTypes.push(type);
}
}
return activeWorkerAndMessagePortTypes;
}

const w = new Worker('', { eval: true });
deepStrictEqual(getActiveWorkerAndMessagePortTypes(), ['WORKER']);
w.unref();
deepStrictEqual(getActiveWorkerAndMessagePortTypes(), []);
w.ref();
deepStrictEqual(getActiveWorkerAndMessagePortTypes(), ['WORKER', 'MESSAGEPORT']);

w.on('exit', common.mustCall((exitCode) => {
strictEqual(exitCode, 0);
deepStrictEqual(getActiveWorkerAndMessagePortTypes(), ['WORKER']);
setTimeout(common.mustCall(() => {
deepStrictEqual(getActiveWorkerAndMessagePortTypes(), []);
}), 0);
}));

0 comments on commit bf9240a

Please sign in to comment.