Concurrent timers in node.js with socket.io - node.js

Question

So I'm developing simple game with the following scenario:
2 users need to start a game (so I'm creating new room for 3rd user and so on)
2 users is maximum per room
When game is started, event is sent to client, after 60 seconds server needs to end the game.
Code which I wrote will work only for 1 room, but for multiple rooms, cancelling is not correct because my lastRoom variable is incorrect.
I'm new to node.js so I'm not really sure how to deal with this.
Some code:
var lastRoom = 'default'; //this is the first created room
function tryToStartGame(socket){
var clients = io.sockets.adapter.rooms[lastRoom];
console.log("Size of room "+lastRoom+" is: "+getObjectSize(clients));
//we are checking size of last room
if (getObjectSize(clients) == 2){
//players in the room should be different
games['default']= {
'leftPlayer': getFromObject(clients, 0),
'rightPlayer': getFromObject(clients, 1),
'stuff': "some data here"
'roomName': lastRoom
};
console.log("We can start the game");
//let all the people in that room
io.to(lastRoom).emit('game', games['default']);
//game to cancel
gameToCancel = lastRoom;
//client needs to be aware when game is ended
//but if we have simultaneous games this will not work
setTimeout(function(){
console.log("Cancelling game in: "+gameToCancel);
io.to(gameToCancel).emit('gameEnded', "Winner logic is todo ;) ");
}, 8000); //after 8 seconds for test
//reset the room name, so next time when this function is called in second room
//we will have something different
lastRoom = 'game'+new Date().getTime();
}
//we have less then 2 players, wait for another player
if (getObjectSize(clients)<2){
console.log("Less then 2 players");
socket.emit('waiting', 'Waiting for another user to join the game');
}
}
And tryToStartGame(socket) function is called always at connection like this:
io.on('connection', function(socket){
//when client says he wants to play
socket.on('joinGame', function(username){
//add user
addUser(socket, username);
//send list of players
io.emit('playersList', getFormatedPlayers());
//figure out in which room this player bellongs
socket.join(lastRoom);
//try to start the game
tryToStartGame(socket);
});
Problematic part is that lastRoom variable is overwritten and then setTimeout picks the wrong room, so what happens that basically last game is canceled, and the previous ones are not.
How should I correctly track and cancel the game in correct rooms ?

Answer 1

As you noted, lastRoom is a global variable and might/will change between the time you set it and the timeout
You can create a closure on the timeout function to keep the room as a locale variable:
var lastRoom = 'default'; //this has to be set in the same function than the call to setTimeout
//client needs to be aware when game is ended
//but if we have simultaneous games this will not work
setTimeout(function(){
var gameToCancel = lastRoom;
console.log("Cancelling game in: "+gameToCancel);
io.to(gameToCancel).emit('gameEnded', "Winner logic is todo ;) ");
}, 8000); //after 8 seconds for test