C # ForEach Loop With ASync Tasks and Dependent Messages ASync Tasks

Question

I am having trouble trying to correctly design the most efficient way to repeat several asynchronous tasks launched from the request object, and then perform some other async tasks that depend on both the request object and the result of the first async task. I am running the C # lambda function in AWS. I tried this model (error handling is omitted for brevity):

public async Task MyAsyncWrapper()
{
  List<Task> Tasks = new List<Task>();
  foreach (var Request in Requests) 
  {
    var Continuation = this.ExecuteAsync(Request).ContinueWith(async x => {
      var KeyValuePair<bool, string> Result = x.Result;
      if (Result.Key == true)
      {
        await this.DoSomethingElseAsync(Request.Id, Request.Name, Result.Value);
        Console.WriteLine("COMPLETED");
      }
    }

    Tasks.Add(Continuation);
  }

  Task.WaitAll(Tasks.ToArray());
}

This approach makes the method DoSomethingElseAsync()not really come to life, and in many of my calls to Lambda Function, I never get the output "COMPLETED". I also approached this method:

public async Task MyAsyncWrapper()
{
  foreach (var Request in Requests) 
  {
    KeyValuePair<bool, string> Result = await this.ExecuteAsync(Request);

    if (Result.Key == true)
    {
      await this.DoSomethingElseAsync(Request.Id, Request.Name, Result.Value);
      Console.WriteLine("COMPLETED");
    }
  }
}

, , , asnyc. Interleaved Tasks, , , , - , ', Request. , :

List<Task<KeyValuePair<bool, string>>> Tasks = new List<Task<KeyValuePair<bool, string>>>();

foreach (var Request in Requests)
{
  Tasks.Add(ths.ExecuteAsync(Request);
}

foreach (Task<KeyValuePair<bool, string>> ResultTask in Tasks.Interleaved())
{
  KeyValuePair<bool, string> Result = ResultTask.Result;
  //Can't access the original request for this method parameters
  await this.DoSomethingElseAsync(???, ???, Result.Value);
}

foreach? , ExecuteAsync(), , .

Answer 1

, "" , Task.WhenAll .

public async Task MyAsyncWrapper()
{
  var allTasks = Requests.Select(ProcessRequest);

  await Task.WhenAll(allTasks);
}

private async Task ProcessRequest(Request request)
{
    KeyValuePair<bool, string> Result = await this.ExecuteAsync(request);

    if (Result.Key == true)
    {
      await this.DoSomethingElseAsync(request.Id, request.Name, Result.Value);
      Console.WriteLine("COMPLETED");
    }
}

Answer 2

TPL:

var a = new TransformBlock<Input, OutputA>(async Input i=>
{
    // do something async.
    return new OutputA();
});

var b = new TransformBlock<OutputA, OutputB>(async OutputA i =>
{
    // do more async.
    return new OutputB();
});

var c = new ActionBlock<OutputB>(async OutputB i =>
{
    // do some final async.
});

a.LinkTo(b, new DataflowLinkOptions { PropogateCompletion = true });
b.LinkTo(c, new DataflowLinkOptions { PropogateCompletion = true });

// push all of the items into the dataflow.
a.Post(new Input());
a.Complete();

// wait for it all to complete.
await c.Completion;