等待.NET 4.0:有意义的堆栈跟踪

Question

我有一个使用.NET 4.0的C#控制台应用程序项目,安装了Microsoft.Bcl.Async软件包.我用这个代码:

internal class Program
{
    private static void Main(string[] args)
    {
        Foo().Wait();
    }

    static void Log(Exception ex)
    {

    }

    private static async Task Foo()
    {
        try
        {
            await DoSomething();
        }
        catch (Exception ex)
        {
            Log(ex);
        }
    }

    private static async Task DoSomething()
    {
        throw new DivideByZeroException();
    }
}

如果我在Log方法中放置一个断点,我得到了DivideByZero异常,但我看到的堆栈跟踪是:

at Microsoft.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at Microsoft.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccess(Task task)
at Microsoft.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
at Microsoft.Runtime.CompilerServices.TaskAwaiter.GetResult()
at AsyncStacks.Program.<Foo>d__0.MoveNext() in p:\Sandbox\AsyncStacks\AsyncStacks\Program.cs:line 25

这个堆栈跟踪几乎没用,因为它没有告诉我实际抛出异常的位置.

如果我将项目更改为目标.NET 4.5,我会得到一个更有用的异常:

at AsyncStacks.Program.<DoSomething>d__3.MoveNext() in p:\Sandbox\AsyncStacks\AsyncStacks\Program.cs:line 35
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at AsyncStacks.Program.<Foo>d__0.MoveNext() in p:\Sandbox\AsyncStacks\AsyncStacks\Program.cs:line 25

如何在使用时从.NET 4.0项目中获取有用的堆栈跟踪await？

更新

"旧的" AsyncTargetingPack确实抛出了更好的堆栈跟踪.这个问题似乎已在"新" Microsoft.Bcl.Async中引入.

Answer 1

改变Foo这种似乎得到一个更好的结果:

private static async Task Foo()
{
    await DoSomething().ContinueWith(t => Log(t.Exception), TaskContinuationOptions.OnlyOnFaulted);
}

更新:但是,缺点是.ContinueWith每次使用await关键字时都必须使用相同的内容.也就是说,如果你等待着等待的东西,你也需要这样做.ContinueWith.