Using HttpContext.Current in WebApi is dangerous because of async

Question

My question is a bit related to this: WebApi equivalent for HttpContext.Items with Dependency Injection.

We want to inject a class using HttpContext.Current in We

Answer 1

I found very good article describing exactly this problem: http://byterot.blogspot.cz/2012/04/aspnet-web-api-series-part-3-async-deep.html?m=1

author investigated deeply, how the ExecuteAsync method is called in the WebApi framework and came to this conclusion:

ASP.NET Web API actions (and all the pipeline methods) will be called asynchronously only if you return a Task or Task. This might sound obvious but none of the pipeline methods with Async suffix will run in their own threads. Using blanket Async could be a misnomer. [UPDATE: ASP.NET team indeed have confirmed that the Async is used to denote methods that return Task and can run asynchronously but do not have to]

What I understood from the article is, that the Action methods are called synchronously, but it is the caller decision.

I created a small test app for this purpose, something like this:

public class ValuesController : ApiController
{
    public object Get(string clientId, string specialValue)
    {
        HttpRequest staticContext = HttpContext.Current.Request;
        string staticUrl = staticContext.Url.ToString();

        HttpRequestMessage dynamicContext = Request;
        string dynamicUrl = dynamicContext.RequestUri.ToString();

        return new {one = staticUrl, two = dynamicUrl};
    }
}

and one Async version returning async Task