每隔60秒向RoR应用发送http put请求的问题

时间：2013-08-13 20:28:24

标签： c# http networking

客户端代码存在一个奇怪的问题，应该每隔60秒向我的RoR网站/应用程序发送HTTP Put请求。

问题在于客户端应用程序向网站推送了一些请求（从2到9请求）。然后客户端代码在几次初始成功推送后停止发送http put请求。

信息：客户端应用程序是C＃windows应用程序。网站正在运行RoR 3.2。

c＃代码发送http put 

    static void HttpPutRequest(string Json)
    {
        Logger("Sending JSON: " + Json);
        try
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create("https://miningmonitor.herokuapp.com/workers/update");
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = "PUT";
            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
                Logger("To URL: " + httpWebRequest.Address.ToString());
                streamWriter.WriteLine(Json);
                streamWriter.Flush();
                streamWriter.Close();
                try
                {
                    var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                    var wRespStatusCode = httpResponse.StatusCode;
                    Logger("Website return code: " + wRespStatusCode.ToString());
                }
                catch (WebException we)
                {
                    var wRespStatusCode = ((HttpWebResponse)we.Response).StatusCode;
                    Logger(" Exception and Website return code: " + wRespStatusCode.ToString());
                }
            }
        }
        catch (WebException we2)
        {
            var GetRequestStreamExp = ((HttpWebResponse)we2.Response).StatusCode;
            Logger(" Exception trying to setup httpWebRequest.GetRequestStream: " + GetRequestStreamExp.ToString());
        }
    }

客户端C＃日志记录语句

Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5953","rejected":"152","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5956","rejected":"152","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.62"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5964","rejected":"152","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5970","rejected":"152","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5978","rejected":"152","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5989","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5995","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
To URL: https://miningmonitor.herokuapp.com/workers/update
Website return code: OK
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"5999","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.63","74.00","0.63"]}
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"6009","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"6015","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.63","73.00","0.64","74.00","0.63"]}
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"6021","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.63"]}
Sending JSON: {"worker_user_name":"test:worker1","hashrate":"1.91","accepted":"6029","rejected":"153","hw_errors":"0","num_gpu":"3","gpus":["72.00","0.64","73.00","0.64","74.00","0.64"]}

从那时起它只创造了json没有发送它。

显示put请求的服务器日志

 Aug 13 10:31:52 miningmonitor heroku/router: at=info method=PUT path=/workers/update host=miningmonitor.herokuapp.com fwd="198.244.99.204" dyno=web.1 connect=8ms service=101ms status=200 bytes=2005

我每隔60秒运行一次是如何在c＃中使用计时器。但我只是困惑为什么代码停止输入using语句，因此停止发送JSON字符串。您可以通过C＃代码中的日志记录语句来说明这一点。我不确定using语句是如何工作的我只是从我在网上发现的一个例子中修改了该语句来发送http请求。因此，如果有人也可以解释那个很棒的使用声明。

添加计时器代码。

    public void update(string user_worker)
    {

      System.Timers.Timer timer = new System.Timers.Timer(60000);
      timer.Elapsed += (sender, e) =>
      {
          //query the miner for summary and gpucount information
          String SummaryQuery = QueryMiner("summary");
          String gpuNum = FindKey(QueryMiner("gpucount"), "Count");
          //String PoolQuery = QueryMiner("pools");
          int numgpus = Convert.ToInt32(gpuNum);
          //Array of strings to hold each gpu query
          String[] gpuQueries = new String[numgpus];
          //add the GPU queries into the array
          for (int i = 0; i < numgpus; i++)
              gpuQueries[i] = QueryMiner("gpu|" + i);

          //now add information specific to each gpu to a list
          List<string> gpuList = new List<string>();
          for (int i = 0; i + 1 <= gpuQueries.Length; i++)
          {
              gpuList.Add(FindKey(gpuQueries[i], "Temperature"));
              gpuList.Add(FindKey(gpuQueries[i], "MHS 5s"));
          }
          //set all the values that we have gotten from the queries
          this.worker_user_name = user_worker;
          this.hashrate = FindKey(SummaryQuery, "MHS av");
          this.accepted = FindKey(SummaryQuery, "Accepted");
          this.rejected = FindKey(SummaryQuery, "Rejected");
          this.hw_errors = FindKey(SummaryQuery, "Hardware Errors");
          this.num_gpu = gpuNum;
          this.gpus = gpuList.ToArray();
          //create JSON from the workerUpdate object
          string JSON = JsonConvert.SerializeObject(this);
          //send to website
          HttpPutRequest(JSON);
      };
     timer.Start();
    }

我现在在日志中发现了异常。例外情况如下。但不确定这意味着什么。

Exception: System.NullReferenceException: Object reference not set to an instance of an object.
 at MiningMonitorClientW.WorkerUpdate.HttpPutRequest(String Json)
 at MiningMonitorClientW.WorkerUpdate.<>c__DisplayClass1.<update>b__0(Object sender, ElapsedEventArgs e)

更新： 所以我做了更多调试，我注意到当我收到错误时，我的代码会一直运行到这一行

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))

也许它试图创建一个streamwrite，当我请求Stream我得到一个null响应？不确定。但例外是说某事是空的。

2 个答案:

答案 0 :(得分：2)

你应该在整个HttpPutRequest方法体上放置一个try / catch块。 httpWebRequest.GetRequestStream()可能失败或超时。

答案 1 :(得分：1)

这不会解决您的问题，但它可以帮助您找出问题所在。

您必须向您的事件处理程序添加try / catch。否则，如果发生异常，您将永远不会知道它，因为System.Timers.Timer将禁止任何逃避处理程序的异常。在下面的代码中，我刚刚在现有代码中添加了try / catch：

public void update(string user_worker)
{

  System.Timers.Timer timer = new System.Timers.Timer(60000);
  timer.Elapsed += (sender, e) =>
  {
    try
    {
      //query the miner for summary and gpucount information
      String SummaryQuery = QueryMiner("summary");
      String gpuNum = FindKey(QueryMiner("gpucount"), "Count");
      //String PoolQuery = QueryMiner("pools");
      int numgpus = Convert.ToInt32(gpuNum);
      //Array of strings to hold each gpu query
      String[] gpuQueries = new String[numgpus];
      //add the GPU queries into the array
      for (int i = 0; i < numgpus; i++)
          gpuQueries[i] = QueryMiner("gpu|" + i);

      //now add information specific to each gpu to a list
      List<string> gpuList = new List<string>();
      for (int i = 0; i + 1 <= gpuQueries.Length; i++)
      {
          gpuList.Add(FindKey(gpuQueries[i], "Temperature"));
          gpuList.Add(FindKey(gpuQueries[i], "MHS 5s"));
      }
      //set all the values that we have gotten from the queries
      this.worker_user_name = user_worker;
      this.hashrate = FindKey(SummaryQuery, "MHS av");
      this.accepted = FindKey(SummaryQuery, "Accepted");
      this.rejected = FindKey(SummaryQuery, "Rejected");
      this.hw_errors = FindKey(SummaryQuery, "Hardware Errors");
      this.num_gpu = gpuNum;
      this.gpus = gpuList.ToArray();
      //create JSON from the workerUpdate object
      string JSON = JsonConvert.SerializeObject(this);
      //send to website
      HttpPutRequest(JSON);
    }
    catch (Exception ex)
    {
        // handle exception here
    }
  };
 timer.Start();
}

编写catch (Exception)通常是不好的做法，但System.Timers.Timer的设计强迫它。正如文档所说：

  

在.NET Framework 2.0及更早版本中， Timer组件捕获并抑制事件处理程序为Elapsed事件抛出的所有异常。此行为在将来的.NET版本中可能会发生变化框架。

从.NET 4.5开始，这种行为没有改变。

如果你没有捕获异常，那么计时器将禁止它，这意味着你永远不会知道发生了异常。

更新

在大多数情况下，您应该只捕获您知道如何处理的特定异常。例如，如果要捕获IOException和WebException，则可以写：

catch (WebException wex)
{
    // handle WebException
}
catch (IOException ioex)
{
    // handle IOException
}

正如我上面所说的那样，抓住Exception被认为是不好的做法，因为你可能不知道如何处理它，并且让你的程序因未处理的异常而崩溃，而不是盲目继续面对一个未知的错误。但是因为System.Timers.Timer会抑制异常，所以你必须捕获Elapsed处理程序中的所有异常，除非记录它们，否则你知道发生了什么。或者你可能有一些方法让你的处理程序通知主线程事情是不正常的，它需要关闭。所以在你的Elapsed处理程序中，你必须抓住你的鼻子并做你通常不应该做的事情。在所有特定的例外之后，添加：

catch (Exception ex)
{
    // handle all other exceptions
}
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