await Async method will create wrong IL

[jerviscui]

TestClass:

[TaskLog]
public class TaskTest
{
    public Task Test()
    {
        Console.WriteLine($"front {Thread.CurrentThread.ManagedThreadId}");

        return Task.Delay(1000);
        //Console.WriteLine("end");
    }
    
    public async Task AwaitTest()
    {
        Console.WriteLine($"front {Thread.CurrentThread.ManagedThreadId}");
        await Task.Delay(10);
        Console.WriteLine($"end {Thread.CurrentThread.ManagedThreadId}");
        //throw new ArgumentException();
    }
}

method boundary Aspect:

public class TaskLogAttribute : OnMethodBoundaryAspect
{
    /// <inheritdoc />
    public override void OnEntry(MethodExecutionArgs arg)
    {
        Console.WriteLine($"OnEntry {Thread.CurrentThread.ManagedThreadId}");
    }

    /// <inheritdoc />
    public override void OnExit(MethodExecutionArgs arg)
    {
        Console.WriteLine($"OnExit {Thread.CurrentThread.ManagedThreadId}");
    }
}

caller:

class Program
{
    static async Task Main(string[] args)
    {
        var t = new TaskTest();
        await t.AwaitTest();
    }
}

The result:

OnEntry 4 OnEntry 4 front 4 OnExit 4 OnExit 4 OnEntry 4 end 4 OnExit 4

[FerdinandBrunauer]

I think your OnExit method should look like the following:

    /// <inheritdoc />
    public override void OnExit(MethodExecutionArgs arg)
    {
        if (arg.ReturnValue is Task t)
        {
            t.ContinueWith(_ =>
            {
                Console.WriteLine($"OnExit {Thread.CurrentThread.ManagedThreadId}");
            }, TaskContinuationOptions.ExecuteSynchronously);
        }
        else
        {
            Console.WriteLine($"OnExit {Thread.CurrentThread.ManagedThreadId}");
        }
    }

[jerviscui]

It's been too long. But, I think I wan to say, OnEntry and OnExit run many times. Beacuse there is many times run OnEntry and OnExit in the TaskStateMachine.

[mjvh80]

I think the issue here is that there's a difference currently whether an aspect is applied to a class or to a method directly. If it is applied directly to an async method there is special handling of the underlying MoveNext (see e.g. https://github.com/vescon/MethodBoundaryAspect.Fody/blob/24034961ad6e358d089abf16b01ec4bf19d98d7b/src/MethodBoundaryAspect.Fody/MethodWeaverFactory.cs#L28) However, if the aspect is applied to the class (or assembly) then it is also applied to the compiler generated state machine class as well, and thus the MoveNext method contained therein.

[Ralf1108]

@mjvh80 so the solution would be to identify the compiler generated state machine class and skip weaving anything in it?