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lib: add return value for DC channel.unsubscribe
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PR-URL: #40433
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
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simon-id authored and danielleadams committed Jan 29, 2022
1 parent a9826b0 commit 594fe55
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Showing 3 changed files with 18 additions and 8 deletions.
5 changes: 5 additions & 0 deletions doc/api/diagnostics_channel.md
Original file line number Diff line number Diff line change
Expand Up @@ -264,9 +264,14 @@ channel.subscribe((message, name) => {
added:
- v15.1.0
- v14.17.0
changes:
- version: REPLACEME
pr-url: https://github.com/nodejs/node/pull/40433
description: Added return value.
-->

* `onMessage` {Function} The previous subscribed handler to remove
* Returns: {boolean} `true` if the handler was found, `false` otherwise.

Remove a message handler previously registered to this channel with
[`channel.subscribe(onMessage)`][].
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16 changes: 9 additions & 7 deletions lib/diagnostics_channel.js
Original file line number Diff line number Diff line change
Expand Up @@ -32,15 +32,17 @@ class ActiveChannel {

unsubscribe(subscription) {
const index = ArrayPrototypeIndexOf(this._subscribers, subscription);
if (index >= 0) {
ArrayPrototypeSplice(this._subscribers, index, 1);
if (index === -1) return false;

// When there are no more active subscribers, restore to fast prototype.
if (!this._subscribers.length) {
// eslint-disable-next-line no-use-before-define
ObjectSetPrototypeOf(this, Channel.prototype);
}
ArrayPrototypeSplice(this._subscribers, index, 1);

// When there are no more active subscribers, restore to fast prototype.
if (!this._subscribers.length) {
// eslint-disable-next-line no-use-before-define
ObjectSetPrototypeOf(this, Channel.prototype);
}

return true;
}

get hasSubscribers() {
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Original file line number Diff line number Diff line change
Expand Up @@ -35,9 +35,12 @@ assert.ok(channel instanceof Channel);
channel.publish(input);

// Should not publish after subscriber is unsubscribed
channel.unsubscribe(subscriber);
assert.ok(channel.unsubscribe(subscriber));
assert.ok(!channel.hasSubscribers);

// unsubscribe() should return false when subscriber is not found
assert.ok(!channel.unsubscribe(subscriber));

assert.throws(() => {
channel.subscribe(null);
}, { code: 'ERR_INVALID_ARG_TYPE' });

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