我可以摆脱这个可怕的阻止代码吗? [英] Can I get rid of this horrible blocking code?

问题描述

我需要一些帮助，在Web api服务调用中，我需要在dll中调用一个异步执行的函数，然后在回调函数中给出响应.现在通常这会很好，但是现在有了Web api，其想法是执行命令，然后返回响应.

I need some help, In a web api service call, I need to call a function in a dll that executes asynchronously, and then gives the response in a call back function. Now normally this would be good , but now with a web api the idea is to execute the command and then return the response.

下面是我当前可以使用的代码，但是我认为它的代码很糟糕，它是您不想执行的所有操作.尤其是在Web服务器上，对于每个请求都将运行此代码时.

Below is my current code which works, but I think its terrible code, its everything you don't want to do. Especially on a web server when this code is going to run for every request.

[HttpGet]
    public HttpResponseMessage Off(string id)
    {
        APNLink.Link link = LinkProvider.getDeviceLink(id, User.Identity.Name);

        if (link.LinkConnectionStatus == APNLink.ConnectionStatus.Connected)
        {
            link.RelayCommand(APNLink.RelayNumber.Relay1, APNLink.RelayCommand.OFF, test);
            BlockForResponse();
            var msg = Request.CreateResponse(HttpStatusCode.OK);
            return msg;
        }
        else
        {
            if (link.Connect())
            {
                var status = link.LinkConnectionStatus;
                int timeout = 0;
                while (status != APNLink.ConnectionStatus.Connected)
                {
                    Thread.Sleep(500);
                    status = link.LinkConnectionStatus;
                    if (status == APNLink.ConnectionStatus.Connected)
                    {
                        break;
                    }                        
                    if (timeout++ > 16)
                    {
                        var msg1 = Request.CreateResponse(HttpStatusCode.RequestTimeout);
                        return msg1;
                    }
                }
                link.RelayCommand(APNLink.RelayNumber.Relay1, APNLink.RelayCommand.OFF, test);
                BlockForResponse();
                var msg = Request.CreateResponse(HttpStatusCode.OK);
                return msg;
            }
            else
            {
                var msg2 = Request.CreateResponse(HttpStatusCode.BadRequest);
                return msg2;
            }
        }

    }

    bool flag = false;

    public void test(bool var)
    {
    flag = true;
    }

     private static bool BlockForResponse()
    {
        int count = 0;
        while (!flag)
        {
            Thread.Sleep(500);
            if (count > 10)
            {
                //timeout
                return false;
            }
        }
        return true;
    }

现在的问题是，我在等待dll，连接连接时必须阻塞，然后才可以执行命令.一旦我执行了命令.然后，我必须再次阻止以获取响应.

now the thing is I have to block when waiting for the dll, Connection to be connected, only then can I execute the command. once I have executed the command. I then have to block again for the response.

另一方面是，我可以实际阻止asp.net线程吗?当然每个请求都不会在自己的线程上处理吗?

Another aspect is, Can I actually block on an asp.net thread? Surely each request is not handled on its own thread?

有什么方法可以使这段代码更整洁，最重要的是更有效吗?

Is there any way I can make this code neater and most importantly more efficient?

推荐答案

回答问题:

在Web api服务调用中，我需要在dll中调用一个函数 异步执行，然后在回调中给出响应 功能.

In a web api service call, I need to call a function in a dll that executes asynchronously, and then gives the response in a call back function.

IMO，执行此操作的最佳方法是使控制器方法异步并使用TaskCompletionSource包装DLL的回调.一些不错的附加读物:

IMO, the best way of doing this is to make your controller method asynchronous and use TaskCompletionSource to wrap the callback of your DLL. Some good additional reads:

• 在ASP.NET MVC 4 .
• TaskCompletionSource<TResult>的性质.

• Using Asynchronous Methods in ASP.NET MVC 4.
• The Nature of TaskCompletionSource<TResult>.

代码可能看起来像这样:

The code may look something like this:

[HttpGet]
public async Task<HttpResponseMessage> Off(string id)
{
    APNLink.Link link = LinkProvider.getDeviceLink(id, User.Identity.Name);

    if (link.LinkConnectionStatus == APNLink.ConnectionStatus.Connected)
    {
        var tcs = new TaskCompletionSource<object>();

        CallbackType test = delegate {           
           tcs.SetResult(null);
        };

        link.RelayCommand(
            APNLink.RelayNumber.Relay1, 
            APNLink.RelayCommand.OFF,
            test);

        // BlockForResponse();
        await tcs.Task; // non-blocking

        var msg = Request.CreateResponse(HttpStatusCode.OK);
        return msg;
    }

    // ...
}

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