在try / catch语句进行的await一个好的解决方案/最后？ [英] A good solution for await in try/catch/finally?

问题描述

我需要重新抛出异常（与它的堆栈跟踪之前调用一个异步方法在抓块）是这样的：

I need to call an async method in a catch block before throwing again the exception (with its stack trace) like this :

try
{
    // Do something
}
catch
{
    // <- Clean things here with async methods
    throw;
}

但不幸的是你不能使用等待在抓或最后块。我了解到这是因为编译器没有任何办法回去了抓块来执行你是什么的await 指令或类似的东西...

But unfortunately you can't use await in a catch or finally block. I learned it's because the compiler doesn't have any way to go back in a catch block to execute what is after your await instruction or something like that...

我试图用 Task.Wait（）来代替等待，我得到了一个僵局。我搜索在网络上我怎么能避免这种情况，发现<一个href=\"http://www.tugberkugurlu.com/archive/the-perfect-recipe-to-shoot-yourself-in-the-foot-ending-up-with-a-deadlock-using-the-c-sharp-5-0-asynchronous-language-features\">this网站。

I tried to use Task.Wait() to replace await and I got a deadlock. I searched on the Web how I could avoid this and found this site.

既然不能改变异步方法，我也不知道，如果他们使用 ConfigureAwait（假），我创建了这些方法，它采取了 Func键＆LT;任务＆GT; 启动异步方法，一旦我们在不同的线程（以避免死锁），并为其完成等待：

Since I can't change the async methods nor do I know if they use ConfigureAwait(false), I created these methods which take a Func<Task> that starts an async method once we are on a different thread (to avoid a deadlock) and waits for its completion:

public static void AwaitTaskSync(Func<Task> action)
{
    Task.Run(async () => await action().ConfigureAwait(false)).Wait();
}

public static TResult AwaitTaskSync<TResult>(Func<Task<TResult>> action)
{
    return Task.Run(async () => await action().ConfigureAwait(false)).Result;
}

public static void AwaitSync(Func<IAsyncAction> action)
{
    AwaitTaskSync(() => action().AsTask());
}

public static TResult AwaitSync<TResult>(Func<IAsyncOperation<TResult>> action)
{
    return AwaitTaskSync(() => action().AsTask());
}

所以我的问题是：你认为这个code是好

So my questions is: Do you think this code is okay?

当然，如果你有一些改进或知道一个更好的方法，我在听！ ：）

Of course, if you have some enhancements or know a better approach, I'm listening! :)

推荐答案

您可以将逻辑抓块外后重新抛出异常，如果需要的话，由使用<一个href=\"http://msdn.microsoft.com/en-us/library/system.runtime.exceptionservices.exceptiondispatchinfo.aspx\"><$c$c>ExceptionDispatchInfo.

You can move the logic outside of the catch block and rethrow the exception after, if needed, by using ExceptionDispatchInfo.

static async Task f()
{
    ExceptionDispatchInfo capturedException = null;
    try
    {
        await TaskThatFails();
    }
    catch (MyException ex)
    {
        capturedException = ExceptionDispatchInfo.Capture(ex);
    }

    if (capturedException != null)
    {
        await ExceptionHandler();

        capturedException.Throw();
    }
}

这样，当主叫检查异常的堆栈跟踪属性，在 TaskThatFails 它仍然记录在那里被扔

This way, when the caller inspects the exception's StackTrace property, it still records where inside TaskThatFails it was thrown.

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