Meteor - Cancelling a Server Method from the Client

Question

I'm performing a database count through a server method. Users can select how they want the count to be performed and then invoke the method.

My problem is that the count can take some time and a user might change their mind while the method is running and request a different count. Is there any way for me to cancel the invoked method and run a new count?

I've thought this.unblock() might work; it will allow a new method to be run, but it won't cancel the old method. I've also considered pre-counting and then just using a lookup, but there are too many selector combinations.

Here's my code, it's fairly simple:

//Server
Meteor.methods({
    getFilterCount: function(oFilterSelector) {
        return clMaBldgs.find(oFilterSelector, {}).count();
    }
});

//Client
Meteor.call('getFilterCount', oFilterSelector, function (error, result) {
    //do some stuff
});

Answer 1

Cancelling an already-made method call to server from client is not possible.

But if your method are called multiple times in a short interval, and you only care about the last call's result. You could use debounce to delay execution for some times. This will help reduce unnecessary calls to server.

Answer 2

More of a work around, but if you had a reactive variable (could be an entry in the DB) that is a status of the method, and in the method itself, you check for that flag every chance you get for the status.

{
    _id: "some id for the method", running: true
}

Pseudocode for method

Meteor.methods({
    method: (_id) => {
        status = getStatusForId(_id);
        while(status) {
            status = getStatusForId(_id);
        }
    }
});

Then to stop it, you just update that flag to be false and the method will stop as soon as it can.