Send async e-mails

Question

I am using ASP.NET MVC 3 with MVCMailer, I tried to send e-mails using SendAsync, but actually it still take longer.

So I am trying to use Task.Factory like the code bellow:

   var task1 = Task.Factory.StartNew(
            state =>
            {
                var mail = new UserMailer();
                var msg = mail.Welcome("My Name", "[email protected]");
                msg.SendAsync(); 
            });

   task1.Wait();

The problem is, MVCMailer needs HttpContext, but inside this task I got HttpContext Null.

How can I send Async e-mails?

Answer 1

A small addition to this. Here is an extension method to help some.

using Mvc.Mailer; 
using System.Threading.Tasks;
public static void SendEmailAsync(this MvcMailMessage msg, HttpContext currContext)
{
      //make this process a little cleaner
      Task.Factory.StartNew(() =>
      {
           System.Web.HttpContext.Current = currContext;
           msg.SendAsync();
       });
}

Use it like follows from your controller methods.

Mailers.UserMailer um = new Mailers.UserMailer();
um.SendWelcomeEmail(dataObject).SendEmailAsync(ControllerContext.HttpContext.ApplicationInstance.Context);

Answer 2

Task.Factory.StartNew will create a new thread.
If you want to access HttpContext which is in the main thread you have to do this:

var task1 = Task.Factory.StartNew(() =>
    {
    System.Web.HttpContext.Current = ControllerContext.HttpContext.ApplicationInstance.Context;
    var mail = new UserMailer();
    var msg = mail.Welcome("My Name", "[email protected]");
    msg.SendAsync();
    });

task1.Wait();

There a long debate if it's better to use TPL or QueueUserWorkItem.
Someone has tried to address the issue.
This is the QueueUserWorkItem version:

public class HomeController : Controller
{
    private AutoResetEvent s_reset = new AutoResetEvent(false);

    public ActionResult Index()
    {
        var state = new WorkerState() { HttpContextReference = System.Web.HttpContext.Current };
        ThreadPool.QueueUserWorkItem(new WaitCallback(EmaiSenderWorker), state);

        try
        {
        s_reset.WaitOne();
        }
        finally
        {
        s_reset.Close();
        }

        return View();
    }

    void EmaiSenderWorker(object state)
    {
        var mystate = state as WorkerState;

        if (mystate != null && mystate.HttpContextReference != null)
        {
        System.Web.HttpContext.Current = mystate.HttpContextReference;
        }

        var mail = new UserMailer();
        var msg = mail.Welcome();
        msg.SendAsync();

        s_reset.Set();
    }

    private class WorkerState
    {
        public HttpContext HttpContextReference { get; set; }
    }

}