while cycle with promise inside and boolean as control variable

Question

I have a function inside a angular js controller. I try to do a while cycle but the stop condition is a result of a promise that I execute in a service. The result is that the cycle is infinity.

My code:

$scope.origin = "table_name";
$scope.start = 1;
$scope.end = new Date().getTime();

$scope.setData = function () {
    var flag = true;
    while(flag)
    {
        service.getData($scope.origin, $scope.start, $scope.end, 0, 100)
                .then(
                        function(res)
                        {
                            if(res.length == 100)
                            {
                                $scope.start = res[res.length - 1].timestamp;
                            }
                            else
                            {
                                flag = false;
                            }
                        },
                        function(err)
                        {
                            flag = false;
                        }
                );
    }
}