Async.Await未捕获任务异常 [英] Async.Await not catching Task exception

问题描述

我有一个不返回任何内容的任务。您无法在此类任务上执行Async.AwaitTask，因此您需要执行Async.AwaitIAsyncTask。不幸的是，这似乎吞没了底层Task抛出的所有异常：-

  TaskFactory（）。StartNew（Action（fun _ -> failwith oops））
 |> Async.AwaitIAsyncResult 
 |>异步忽略
 |> Async.RunSynchronously 
 
 // val：unit =（）
  

打开另一方面，AwaitTask正确地级联了该异常：-

  TaskFactory（）。StartNew（fun _-> failwith oops 
 5）
 |> Async.AwaitTask 
 |>异步忽略
 |> Async.RunSynchronously 
 
 // POP！ 
  

将常规（非通用）任务视为异步但仍能传播异常的最佳方法是什么？

解决方案

来自 Xamarin F＃衬衫应用程序（我最初从戴夫·托马斯那里借来的）：

> [< AutoOpen>]
模块Async =
让内联awaitPlainTask（task：Task）=
//如果出错$ b $，则从先前任务中抛出异常b让continuation（t：Task）=如果t.IsFaulted然后引发t.Exception
task.ContinueWithcontinuation |> Async.AwaitTask


I have a Task that does not return anything. You can't do an Async.AwaitTask on such a Task, so you need to do an Async.AwaitIAsyncTask instead. Unfortunately this seems to just swallow any exceptions that the underlying Task throws out: -

TaskFactory().StartNew(Action(fun _ -> failwith "oops"))
|> Async.AwaitIAsyncResult
|> Async.Ignore
|> Async.RunSynchronously

// val it : unit = ()

On the other hand, AwaitTask correctly cascades the exception: -

TaskFactory().StartNew(fun _ -> failwith "oops"                               
                                5)
|> Async.AwaitTask
|> Async.Ignore
|> Async.RunSynchronously

// POP!

What's the best way of treating regular (non-generic) Tasks as Async yet still get propagation of exceptions?

解决方案

From the Xamarin F# Shirt App (which I originally borrowed from Dave Thomas):

[<AutoOpen>]
module Async =
     let inline awaitPlainTask (task: Task) = 
        // rethrow exception from preceding task if it faulted
        let continuation (t : Task) = if t.IsFaulted then raise t.Exception
        task.ContinueWith continuation |> Async.AwaitTask

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