針對多個客戶端的C＃.NET UDP套接字異步

Question

我一直在環顧四周，無法真正找到我需要的東西，特別是對於UDP。

我試圖做一個基本的系統日誌服務器偵聽端口514（UDP）。

我一直在關注微軟的MSDN上的指南：https://msdn.microsoft.com/en-us/library/system.net.sockets.udpclient.beginreceive(v=vs.110).aspx

它不明確狀態（或者我瞎了）如何重新打開更多的數據包的連接被收到。

這裏是我的代碼（也就是從鏈路都相同）

 static void Main(string[] args) 
    { 
     try 
     { 
      ReceiveMessages(); 

      Console.ReadLine(); 

     }catch(SocketException ex) 
     { 
      if(ex.SocketErrorCode.ToString() == "AddressAlreadyInUse") 
      { 
       MessageBox.Show("Port already in use!"); 
      } 
     } 

    } 

    public static void ReceiveMessages() 
    { 
     // Receive a message and write it to the console. 



     UdpState s = new UdpState(); 

     Console.WriteLine("listening for messages"); 
     s.u.BeginReceive(new AsyncCallback(ReceiveCallback), s); 
     RecieveMoreMessages(s); 
    } 

    public static void RecieveMoreMessages(UdpState s) 
    { 
     s.u.BeginReceive(new AsyncCallback(ReceiveCallback), s); 
    } 

    public static void ReceiveCallback(IAsyncResult ar) 
    { 
     UdpClient u = (UdpClient)((UdpState)(ar.AsyncState)).u; 
     IPEndPoint e = (IPEndPoint)((UdpState)(ar.AsyncState)).e; 

     Byte[] receiveBytes = u.EndReceive(ar, ref e); 
     string receiveString = Encoding.ASCII.GetString(receiveBytes); 

     Console.WriteLine("Received: {0}", receiveString); 
    } 

我試圖重申，但我後2個交易運行到「暗戰的緩衝空間」從插座中的錯誤。

任何想法？

Answer 1

如果您堅持使用過時的APM模式，則需要撥打ReceiveCallback發出下一個BeginReceive呼叫。

由於UDP是無連接的異步IO似乎毫無意義。可能應該使用同步接收循環：

while (true) { 
client.Receive(...); 
ProcessReceivedData(); 
} 

刪除所有異步代碼。

如果你堅持異步IO至少使用ReceiveAsync。

Answer 2

msdn代碼有一個你消除的睡眠。你不需要睡覺，但你需要一個塊。嘗試這些更改

 public static void ReceiveMessages() 
     { 
      // Receive a message and write it to the console. 



      UdpState s = new UdpState(); 

      Console.WriteLine("listening for messages"); 
      s.u.BeginReceive(new AsyncCallback(ReceiveCallback), s); 
      //block 
      while (true) ; 
     } 

     public static void RecieveMoreMessages(UdpState s) 
     { 
      s.u.BeginReceive(new AsyncCallback(ReceiveCallback), s); 
     } 

     public static void ReceiveCallback(IAsyncResult ar) 
     { 
      UdpClient u = (UdpClient)((UdpState)(ar.AsyncState)).u; 
      IPEndPoint e = (IPEndPoint)((UdpState)(ar.AsyncState)).e; 

      Byte[] receiveBytes = u.EndReceive(ar, ref e); 
      string receiveString = Encoding.ASCII.GetString(receiveBytes); 

      Console.WriteLine("Received: {0}", receiveString); 
      RecieveMoreMessages(ar.AsyncState); 
     }​