angularjs share data state between service and controller

gistfile1.js

var myApp = angular.module('myApp', []);

myApp.factory('srv', function ($rootScope) {
    srv = {
        arr: []
    };

    var val = 1
    setInterval(function () {
        $rootScope.$apply(function () {
            srv.arr.push(val++);
            if (srv.arr.length > 3) {
                srv.arr.shift()
            }
        });
    }, 500);
    return srv

});

function MyCtrl($scope, srv) {
    $scope.arr = srv.arr
}