WPF 等待来自 UI 线程的切换

Question

I have a function called from the UI thread, I'm double checking if that's so by

System.Windows.Threading.Dispatcher.FromThread(System.Threading.Thread.CurrentThread)

everything is called from a void method, which can't be async void because it has an out parameter (method from 3rd party API).

So in this void method I make a call to an async method, the main method doesn't have to wait, so I just run it and forget (planning to handle exceptions in the ContinueWith method, but I'm not there yet).

Problem is, that when in the method chain an await is performed on the ExecuteTaskAsync method of the RestSharp client, after that line, the thread is witched to MTA, the SynchronizationContext.Current is different too.

Why is this happening? Shouldn't the await keyword return to the orginal SynchronizationContext? Why is the SynchronizationContext.Current changing during that call?

Sorry for no code snippets, it's a part of a bigger app and it's hard to snippet it out, but I'm doing it right now, so code snippets will be added.

Answer 1

Ok, resolved it, the mentioned void method from the 3rd party API, was running with a thread that has a dispatcher, because

System.Windows.Threading.Dispatcher.FromThread(System.Threading.Thread.CurrentThread)

Returned a dispatcher, I don't know why, but that didn't matter, I had to run my async method in an Invoke like

Application.Current.Dispatcher.Invoke(() => myAsyncMethod());

and then the await in my method didn't switched the SynchronizationContext . It looks like my assumption that when there is a dispatcher it's the proper context was wrong, don't know why :)