超时后是否需要调用EndInvoke？

Question

在网页上,我正在呼叫第三方,它不允许我以编程方式设置超时.我调用BeginInvoke并使用AsyncWaitHandle.WaitOne等待指定的时间.

如果呼叫超时,我继续前进,忘记我开始的线程呼叫.我的问题是,在超时情况下,我是否还要以某种方式调用EndInvoke？这个MSDN页面上的"注意"注释让我想知道我是否应该:http://msdn.microsoft.com/en-us/library/2e08f6yc(VS.71).aspx

如果您认为我应该,那么接下来的问题是,如果我的网页已经完成处理并在第三方回来之前返回到客户端,那么回调方法是否会在那里听取运行代码？一旦我的请求/响应完成,服务器是否停止寻找活动？

这是我正在使用的代码:

public class RemotePaymentProcessor
{
    private delegate string SendProcessPaymentDelegate(string creditCardNumber);

    private string SendProcessPayment(string creditCardNumber)
    {
        string response = string.Empty;
        // call web service
        SlowResponseService.SlowResponseService srs = new WebServiceTimeout.SlowResponseService.SlowResponseService();
        response = srs.GetSlowResponse(creditCardNumber);
        return response;
    }

    public string ProcessPayment(string creditCardNumber, int timeoutMilliseconds)
    {
        string response = string.Empty;

        SendProcessPaymentDelegate sppd = new SendProcessPaymentDelegate(SendProcessPayment);
        IAsyncResult ar = sppd.BeginInvoke(creditCardNumber, null, new object());
        if (!ar.AsyncWaitHandle.WaitOne(timeoutMilliseconds, false))
        {
            // Async call did not return before timeout
            response = "TIMEOUT";
        }
        else
        {
            // Async call has returned - get response
            response = sppd.EndInvoke(ar);
        }
        return response;
    }
}

Answer 1

好吧，我不能忽视我到处看到的建议，如果我不确保调用 EndInvoke，我可能会泄漏一些资源，所以我不得不尝试在晚上睡觉，而不用担心我正在接近悬崖。

我找到的解决方案使用了异步回调函数。如果调用及时返回，我会在那里调用 EndInvoke。如果没有，我继续单击按钮，并让异步回调函数使用 EndInvoke 清理混乱。

为了回答我自己关于网络应用程序的问题以及“在我超时并继续前进后，是否有人会在那里听”，我发现他们会 - 即使我超时并继续前进，如果我观看了稍后的输出，那么异步即使我已经将输出返回给客户端，调用也会返回并运行回调函数。

我使用了一些我在以下位置找到的内容：http://www.eggheadcafe.com/tutorials/aspnet/847c94bf-4b8d-4a66-9ae5-5b61f049019f/basics-make-any-method-c.aspx

...以及与我在其他地方找到的回调内容相结合。这是我下面所做的一个小示例函数。它结合了我在感谢大家的意见中找到的一些内容！：

public class RemotePaymentProcessor
{    
    string currentResponse = string.Empty;

    private delegate string SendProcessPaymentDelegate(string creditCardNumber);    
    private string SendProcessPayment(string creditCardNumber)    
    {        
        SlowResponseService.SlowResponseService srs = new WebServiceTimeout.SlowResponseService.SlowResponseService();        
        string response = srs.GetSlowResponse(creditCardNumber);        
        return response;    
    }    

    public string ProcessPayment(string creditCardNumber, int timeoutMilliseconds)    
    {        
        string response = string.Empty;        
        SendProcessPaymentDelegate sppd = new SendProcessPaymentDelegate(SendProcessPayment);        
        IAsyncResult ar = sppd.BeginInvoke(creditCardNumber,  new AsyncCallback(TransactionReturned), sppd);        
        if (!ar.AsyncWaitHandle.WaitOne(timeoutMilliseconds, false))        
        {            
            // Async call did not return before timeout            
            response = "TIMEOUT";        
        }        
        else            
        {            
            // Async call has returned - get response            
            response = sppd.EndInvoke(ar);        
        }        

        currentResponse = response; // Set class variable
        return response;    
    }

    private void TransactionReturned(IAsyncResult ar)
    {
        string response = string.Empty;

        // Get delegate back out of Async object
        SendProcessPaymentDelegate sppd = (SendProcessPaymentDelegate)ar.AsyncState;

        // Check outer class response status to see if call has already timed out
        if(currentResponse.ToUpper().Equals("TIMEOUT"))
        {
            // EndInvoke has not yet been called so call it here, but do nothing with result
            response = sppd.EndInvoke(ar);
        }
        else
        {
            // Transaction must have returned on time and EndInvoke has already been called.  Do nothing.
        }       

    }
}