socket.join() sometimes (!) does not work

[helios1138]

I have a system in which a lot of clients are constantly joining and leaving rooms and I see this weird behavior in which I do:

socket.join(someRoom);

and them on the next line I have:

console.log(io.of('/').adapter.rooms[someRoom][socket.id])

which prints true most of the time, but sometimes I get undefined

in Socket class source code I see this line that stops socket from joining the room:

if (~this.rooms.indexOf(room)) return this;

So I now I see that problem is that adapter.rooms and socket.rooms are out of sync for some reason.

Also in the Adapter.prototype.add() I see this:

if (fn) process.nextTick(fn.bind(null, null));

So apparently adapter.rooms and socket.rooms are updated in different event loops. Might this be causing the problem?

[fourpixels]

I was also checking this today. I have no idea why the process.nextTick is used. Any clues?
Anyways, your pull request seems legit to me.
I still don't understand why those rooms are so complicated. There is another issue suggesting simple Object mapping, which is pretty fast compared to Array search / modifications. Might wanna check it.

[darrachequesne]

Hi! This issue should be solved now, with the following merged PR:

• converted arrays to objects #2239 (object mapping)
• Trigger callback even when joining an already joined room #2325 (trigger callback on already joined room)

(should be released with the forthcoming version)