node/test/parallel/test-diagnostics-channel-pub-sub.js
Stephen Belanger 6fb74c743c
diagnostics_channel: fix ref counting bug when reaching zero subscribers
PR-URL: https://github.com/nodejs/node/pull/47520
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
2023-04-13 13:40:50 +00:00

52 lines
1.4 KiB
JavaScript

'use strict';
const common = require('../common');
const dc = require('diagnostics_channel');
const assert = require('assert');
const { Channel } = dc;
const name = 'test';
const input = {
foo: 'bar'
};
// Individual channel objects can be created to avoid future lookups
const channel = dc.channel(name);
assert.ok(channel instanceof Channel);
// No subscribers yet, should not publish
assert.ok(!channel.hasSubscribers);
const subscriber = common.mustCall((message, name) => {
assert.strictEqual(name, channel.name);
assert.deepStrictEqual(message, input);
});
// Now there's a subscriber, should publish
dc.subscribe(name, subscriber);
assert.ok(channel.hasSubscribers);
// The ActiveChannel prototype swap should not fail instanceof
assert.ok(channel instanceof Channel);
// Should trigger the subscriber once
channel.publish(input);
// Should not publish after subscriber is unsubscribed
assert.ok(dc.unsubscribe(name, subscriber));
assert.ok(!channel.hasSubscribers);
// unsubscribe() should return false when subscriber is not found
assert.ok(!dc.unsubscribe(name, subscriber));
assert.throws(() => {
dc.subscribe(name, null);
}, { code: 'ERR_INVALID_ARG_TYPE' });
// Reaching zero subscribers should not delete from the channels map as there
// will be no more weakref to incRef if another subscribe happens while the
// channel object itself exists.
channel.subscribe(subscriber);
channel.unsubscribe(subscriber);
channel.subscribe(subscriber);