串行端口和AutoResetEvent问题 [英] Problem with Serial Port and AutoResetEvent

问题描述

亲爱的所有人

我有一个通讯类，它确实使用 SerialPort 进行通讯.我的第一个实现对端口进行了轮询，并且非常高效.因为我讨厌投票，所以我试图替换它.

我的想法:
-我迷上了 SerialPort.DataReceived . DataReceived 将从 SerialPort 线程中调用
-我的 DataReceived 检查条件，并将 AutoResetEvent 设置为发出信号，表明条件是否符合条件
-主线程使用 AutoResetEvent.WaitOne ()等待.

问题:
即使 DataReceived 发出 AutoResetEvent 信号，主线程也会冻结.

提前谢谢.
问候


代码片段:

Dear all

I have a communication class which does use SerialPort to communicate. My first implementation polled the port and was very efficient. Because I hate polling I tried to replace it.

My idea:
- I hook into SerialPort.DataReceived. DataReceived will be called from a the SerialPort thread
- My DataReceived checks the condition and set an AutoResetEvent to signaled if the condition meats the criterion
- The main thread waits using AutoResetEvent.WaitOne().

Problem:
Even while DataReceived signales AutoResetEvent, the main thread freezes.

Thanks in advance.
Regards


code fragments:

class CommunicationDeviceSerialPort : CommunicationDevice
{
  System.IO.Ports.SerialPort  serialPort  = new System.IO.Ports.SerialPort();
  AutoResetEvent              recSynchObj = new AutoResetEvent(false)
	
  // Hook for SerialPort.DataReceived. Called by the SerialPort receiver thread
  private void SerialDataReceivedEvent(object sender, SerialDataReceivedEventArgs e)
  {
    // Acoording to MSN docu, this will be called from a background thread


    // read in pending SerialPort data into deviceBuffer
    ... deviceBuffer

    // Check condition
    if (deviceBuffer meats my condition)
       recSynchObj.Set();
  }

  // Communicate will be called from the main thread 
  public int Communicate(String Command, int TimeoutMS, out Data)
  {
    // Some Cleanup
    ...

    // Send the command
    serialPort.Write(Command);

    // Ininite timeou for tests
    bool xSignaled= recSynchObj.WaitOne();  

    //************************************
    //****It never comes out of WaitOne one line above. Why???*****
    //************************************

    if (xSignaled)
    {
        // Read data from devicebuffer
        ...
    }

    // With Progress in final version
    /*
    while(true)
    {
      bool xSignaled= recSynchObj.WaitOne(250);
      if (xSignaled)
      {
        // Read data from devicebuffer
        ...
        break;
      }
      // ShowProgress();
      // CheckTimeout()
    }
    */
  }
}

class FormMain
{
  CommunicationDevice commDevice= new CommunicationDeviceSerialPort();

  private void DoCommunicate
  {
    // Send somthing
    commDevice.Communicate(cmd, 2000, );	
  }	
}

推荐答案

不要等待主线程.这可能会导致消息泵被完全阻止，这意味着WaitHandles永远不会收到通知它们已经完成到应用程序以及锁定UI的通知.

Don''t wait on the main thread. That can cause the message pump to be completely blocked and that means WaitHandles never get the notification that they''re done through to the application, as well as locking the UI.

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