AngularJS应用程序初始化之前的$ http请求？

In order to determine if a user's session is authenticated, I need to make a $http request to the server before the first route is loaded. Before each route is loaded, an authentication service checks the status of the user and the access level required by the route, and if the user isn't authenticated for that route, it redirects to a login page. When the app is first loaded however, it has no knowledge of the user, so even if they have an authenticated session it will always redirect to the login page. So to fix this I'm trying to make a request to the server for the users status as a part of the app initialisation. The issue is that obviously $http calls are asynchronous, so how would I stop the app running until the request has finished?In order to determine if a user's session is au