Resolving Autofac components in background Tasks in ASP.NET

Question

Using Autofac in ASP.NET along with the ContainerDisposalModule, how can i support fire and forget calls that have component dependencies that need to be resolved? The prob

Answer 1

Answer posted by Alex adapted to current Autofac and MVC versions:

• Use InstancePerRequest for a database context
• Add ILifetimeScope as dependency to get to the container
• SingleInstance ensures it's the root lifetime scope
• Use HostingEnvironment.QueueBackgroundWorkItem to reliably run something in the background
• Use MatchingScopeLifetimeTags.RequestLifetimeScopeTag to avoid having to know the tagname autofac uses for PerRequest lifetimes

https://groups.google.com/forum/#!topic/autofac/gJYDDls981A https://groups.google.com/forum/#!topic/autofac/yGQWjVbPYGM

Gist: https://gist.github.com/janv8000/35e6250c8efc00288d21

Global.asax.cs:

protected void Application_Start() {
  //Other registrations
  builder.RegisterType();
  builder.RegisterType().As().InstancePerRequest();  //WebsiteContext is a EF DbContext
  builder.RegisterType().As().SingleInstance();
}

AsyncRunner.cs

public interface IAsyncRunner
{
    void Run(Action action);
}

public class AsyncRunner : IAsyncRunner
{
    public ILifetimeScope LifetimeScope { get; set; }

    public AsyncRunner(ILifetimeScope lifetimeScope)
    {
        Guard.NotNull(() => lifetimeScope, lifetimeScope);
        LifetimeScope = lifetimeScope;
    }

    public void Run(Action action)
    {
        HostingEnvironment.QueueBackgroundWorkItem(ct =>
        {
            // Create a nested container which will use the same dependency
            // registrations as set for HTTP request scopes.
            using (var container = LifetimeScope.BeginLifetimeScope(MatchingScopeLifetimeTags.RequestLifetimeScopeTag))
            {
                var service = container.Resolve();
                action(service);
            }
        });
    }
}

Controller

public Controller(IAsyncRunner asyncRunner)
{
  Guard.NotNull(() => asyncRunner, asyncRunner);
  AsyncRunner = asyncRunner;
}

public ActionResult Index()
{
  //Snip
  AsyncRunner.Run(listingService => listingService.RenderListing(listingGenerationArguments, Thread.CurrentThread.CurrentCulture));
  //Snip
}

ListingService

public class ListingService : IListingService
{
  public ListingService(IWebsiteContext context)
  {
    Guard.NotNull(() => context, context);
    Context = context;
  }
}