如何将安全主体从我的请求传递到asp.net MVC中的线程

Question

In my ASP.net MVC application I have a request that does a lot of calculations to return the result. This works fine on my own servers, but when I move to Azure the connection/request gets closed after 4 minutes so I don't ever get the results back I just get an error.

To resolve this I was planning to run the long calculation in a thread and have the client poll to see when it is done.

I have tried all sorts of ways of doing this (threads, thread pools, tasks and hangfire) but i can't get the security context/principal/identity to pass from my request to my new thread.

Here is some sudo code for what I am doing. (I realize that there should be some better synchronization for multiple requests, but this is sudo code)

    public static void SlowCalculation(params)
    {
        _calculationIsRunning = true;
        var principal = System.Security.Principal.GenericPrincipal.Current;
        if (principal?.IsInRole("MySecurityGroup") ?? false)
        {
            // lots of long calculations
            _resutsAreReady = true;
            _calculationIsRunning = true;
        }
    }

    //
    // POST: /Get/
    public ActionResult GetResults(params)
    {
        if (_calculationIsRunning)
            return View("InProgress");
        else if (_resutsAreReady)
            return View("Results", results);
        else            
            // start the calcualtion on a new thread to avoiding having very long running connection that azure will close
            System.Threading.Tasks.Task.Run(() => SlowCalculation(params));
     }

The security check that I show in SlowCalculation is actually berried way down in some libraries I use, so I don't really want to change that if I can help it. I just want to get the principal from my request into my thread.

I have tried passing the identity into the thread function, but it gets disposed when the request completes.

Answer 1

Why are you trying to check the security principal in each thread. You only need to check the security principal before running the SlowCalculation method.

Or if you really want to

public static void SlowCalculation(params, System.Security.Principal.GenericPrincipal principal)
{
    _calculationIsRunning = true;
    if (principal.IsInRole("MySecurityGroup") ?? false)
    {
        // lots of long calculations
        _resutsAreReady = true;
        _calculationIsRunning = true;
    }
}

//
// POST: /Get/
public ActionResult GetResults(params)
{
    if (_calculationIsRunning)
        return View("InProgress");
    else if (_resutsAreReady)
        return View("Results", results);
    else            
    {
        // start the calcualtion on a new thread to avoiding having very long running connection that azure will close
        var principal = System.Security.Principal.GenericPrincipal.Current;
        System.Threading.Tasks.Task.Run(() => SlowCalculation(params, principal));
    }
 }

Answer 2

It's not a good idea to have long running background threads in an ASP.NET process. The proper way to solve this is to put a calculation request on the Azure service bus for example and have some worker process be notified of this and run the calculation.

You can do your authorization check in the web application and have the worker process execute the calculation without authorization check. If the calculation depends on the user's identity, things get a little more difficult as you'll need to deal with the possibility of session/token expiration. See my question here for how to deal with that.