.Net Async ContinueWith VS在任务中嵌入任务

Question

只是想知道异步时最好的方法.起初我的代码看起来像这样(示例简化了).

public NotificationSummary SendNotification()
{
      var response = new NotificationSummary();
      var first = FindSubscriptions(1);
      ... 
      var seventh = FindSubscriptions(7);

      Task.WaitAll(first, ... , seventh);

      response.First = first.Result;
      ...
      response.Seventh = seventh.Result;
      return response;
}


private Task<NotificationResult> FindSubscriptions(int day)
{
     return Task.Run(() => 
     {
        var subscriptions = // call to database to get list of subscriptions
        var tasks = subscriptions.Select(x =>  SendOutNotification(x))
        var results = Task.WhenAll(tasks).Result.ToList();
        return // map results to NotificationResult
     }
}


private Task<IndividualResult> SendOutNotification(Subscription subscription)
{
    return Task.Run(() => 
    {
       var response = new IndividualResult();
       foreach(var user in subscription.Users)
       {
            try
            {
                 // Send user info to EMAIL API
                 response.Worked.Add(user);
            }
            catch(Exception ex) { response.Failed.Add(user)}
       }

       return response;
    }
}

但是这种方法违反了单一责任,当他们来试图弄清楚这些代码在做什么时,可能会让其他开发人员感到困惑.我试图找到一种方法将任务链接在一起,我遇到了ContinueWith.我做了一些研究(也看了看其他stackoverflow帖子),我对ContinueWith进行了混合评论.我真的希望我的SendNotification方法看起来像这样,但我不知道这对于异步和任务是否是一个好方法.

public NotificationSummary SendNotification()
{
    var response = new NotificationSummary();
    var firstTasks = new List<IndivdualResult>();
    var first = FindSubscriptions(1).ContinueWith( x=>
                  x.Result.ForEach(r =>
                    firstTasks.Add(SendOutNotification(x).Result)));
   response.First = // map first;

   // do 2 - 7 tasks as well

   return response;
}

private Task<List<Subscription>> FindSubscriptions() {} //returns subscriptions

private Task<IndividualResults> SendOutNotication() {} // same as above

我想知道这些方法中的哪一种会被视为"正确的方法",如果有的话？

Answer 1

ContinueWith是await可用的代码味道.await基本上是附加延续的好方法.

我发现第一版代码没有结构问题.你可能应该:

• 用.替换所有Wait/Result呼叫await
• 删除Task.Run用法
• 用等待WhenAll替换WaitAll
• 用一个新的异步方法替换ContinueWith并等待

这应该清理混乱并解决效率问题.

如果您不需要并行性,您也可以使所有内容同步.