How to handle async concurrent requests correctly?

Question

Let\'s say I have some sort of game. I have a buyItem function like this:

buyItem: function (req, res) {
    // query the users balance
    // deduct user ba         


        

Answer 1

I haven't tested this out. But as long as your not using multiple instances or clusters, you should just be able to store the status in memory. Because node is single threaded there shouldn't be any problems with atomicity.

var inProgress = {};

function buyItem(req, res) {
    if (inProgress[req.session.user.id]) {
        // send error response
        return;
    }

    inProgress[req.session.user.id] = true;

    // or whatever the function is..
    req.session.user.subtractBalance(10.00, function(err, success) {
        delete inProgress[req.session.user.id];

        // send success response
    });
}