为什么不触发异步套接字 send.completed 事件？

Question

正在尝试发出 uPNP 发现请求。希望问题很简单。 SendEvent_Completed 没有被解雇是有原因的吗？

public void Send() {
  var request = $"M-SEARCH * HTTP/1.1\r\nHOST: 239.255.255.250:1900\r\nMAN: \"ssdp:discover\"\r\nMX: 1\r\nST: ssdp:all\r\n";
  var requestData = Encoding.UTF8.GetBytes(request);

  var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
  socket.SendBufferSize = requestData.Length;

  var sendEvent = new SocketAsyncEventArgs();
  sendEvent.RemoteEndPoint = new IPEndPoint(IPAddress.Parse("239.255.255.250"), 1900);
  sendEvent.SetBuffer(requestData, 0, requestData.Length);
  sendEvent.Completed += SendEvent_Completed; ;

  socket.SendToAsync(sendEvent);
}

private void SendEvent_Completed(object sender, SocketAsyncEventArgs e) {
  Console.WriteLine("SendEvent_Completed"); // never called why?!
}

Answer 1

它不会被提出的明显原因是 SendToAsync returns false:

false if the I/O operation completed synchronously. In this case, The Completed event on the e parameter will not be raised and the e object passed as a parameter may be examined immediately after the method call returns to retrieve the result of the operation.

由于您目前根本没有检查该值，因此无法知道事件 是否会 在您当前的代码中引发。

为什么不触发异步套接字 send.completed 事件？

Why is the async socket send.completed event not fired?

c#

sockets

upnp

asyncsocket