Buffer data from database cursor while keeping UI responsive

Question

I have a database catalog that is populated, and a cursor that can be used to retrieve objects. This catalog can obviously be very large, and what I\'d like to do is use

Answer 1

Your problem is here:

           while (status == DbStatus.OK)
            {
                var dbObject= Db.Create(cursor);
                obs.OnNext(dbObject);

                status = cursor.MoveToNext();
            }

That loop runs synchronously as soon as someone subscribes, in a blocking way. Since you're creating the subscription on the UI thread (at the time you call Connect), it will run the entire thing on the UI thread. Change it to:

return Observable.Create(obs =>
{
    Observable.Start(() => {
        var cursor = Database.Instance.GetAllObjects();
        var status = cursor.MoveToFirst();

        while (status == DbStatus.OK)
        {
            var dbObject= Db.Create(cursor);
            obs.OnNext(dbObject);

            status = cursor.MoveToNext();
        }

        obs.OnCompleted();
    }, RxApp.TaskPoolScheduler);

    return Disposable.Empty;
});