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[英]C# UWP Socket: using ReceiveAsync / SendAsync and handling a timeout without closing the socket
[英]C#: Trouble with socket ReceiveAsync and SendAsync on Remote Host
首先,我想说的是,带有服务器/客户端的代码在我的PC上运行正常(客户端和服务器都在同一台PC上运行)
当我在专用服务器上托管服务器时,问题开始。 第二次我尝试与客户端发送或接收时,客户端将花费大量时间来完成操作(谈论接收1个字节的数据需要花费超过1个小时的时间!)
**我可以通过在每次发送/接收命令后再次简单地断开并重新连接套接字来避免此问题
我不明白为什么如果我要在同一连接会话中执行多于1个发送/接收操作的时间,那么要花那么多时间。
这是一个例子:
连接服务器:
RC_Server = new SocketConnection_Client(RC_IpEndPoint);
现在客户端已连接到服务器,并且我可以正常开始发送/接收。
我第一次尝试发送或接收它时,它的工作原理非常完美且快速(无论缓冲区长度如何)。
RC_Server.sendCompleted = false;
RC_Server.Send(buffer); //in this case buffer size is 1024
while (!RC_Server.sendCompleted) { } //here thread is waiting for the send to complete
现在,如果我想开始与服务器的接收会话
RC_Server.receiveCompleted = false;
RC_Server.Receive(buffer.Length); //in this case byffer needs to get 4 bytes from server
while (!RC_Server.receiveCompleted) { } // <<- Here it will take VERY long time for the operation to complete
buffer = RC_Server.buffer;
第二个接收操作永远不会到达socket_receiveCompleted_Completed事件。
但是..如果我将在第一个发送/接收会话后关闭与服务器的连接,然后打开与服务器的新连接,然后执行下一个发送/接收会话,那么一切都会正常进行。 (并多次重复此方法以进行多次发送/接收)
再次,该问题不会在我的工作站中发生(如果我在同一台PC上运行服务器和客户端)。 仅当我将服务器托管在远程主机上时,它才会发生。
这是我的套接字类的一部分:
class SocketConnection_Client
{
public string errorMsg = string.Empty;
public bool receiveCompleted = false;
public bool sendCompleted = false;
int bytesReceived = 0;
public byte[] buffer;
Socket socket;
public SocketConnection_Client(IPEndPoint ipEP)
{
socket = new Socket(ipEP.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
try
{
socket.Connect(ipEP);
}
catch (Exception ex)
{
errorMsg = ex.Message;
socket.Dispose();
socket = null;
}
}
public void Send(byte[] sBuffer)
{
buffer = null;
if (socket == null)
{
sendCompleted = true;
return;
}
sendCompleted = false;
SocketAsyncEventArgs socket_sendCompleted = new SocketAsyncEventArgs();
socket_sendCompleted.SetBuffer(sBuffer, 0, sBuffer.Length);
socket_sendCompleted.Completed += socket_sendCompleted_Completed;
socket.SendAsync(socket_sendCompleted);
}
void socket_sendCompleted_Completed(object sender, SocketAsyncEventArgs e)
{
sendCompleted = true;
}
public void Receive(int bLength)
{
bytesReceived = 0;
buffer = null;
if (socket == null)
{
receiveCompleted = true;
return;
}
receiveCompleted = false;
buffer = new byte[bLength];
SocketAsyncEventArgs socket_receiveCompleted = new SocketAsyncEventArgs();
socket_receiveCompleted.SetBuffer(buffer, 0, buffer.Length);
socket_receiveCompleted.Completed += socket_receiveCompleted_Completed;
socket.ReceiveAsync(socket_receiveCompleted);
}
private void Receive_Continue()
{
SocketAsyncEventArgs socket_receiveCompleted = new SocketAsyncEventArgs();
socket_receiveCompleted.SetBuffer(buffer, bytesReceived, buffer.Length - bytesReceived);
socket_receiveCompleted.Completed += socket_receiveCompleted_Completed;
socket.ReceiveAsync(socket_receiveCompleted);
}
void socket_receiveCompleted_Completed(object sender, SocketAsyncEventArgs e)
{
bytesReceived += e.BytesTransferred;
if (e.BytesTransferred == 0 && bytesReceived == 0)
{
socket.Dispose();
socket = null;
receiveCompleted = true;
throw new Exception("Server Disconnected");
}
else if (bytesReceived != buffer.Length)
Receive_Continue();
else
receiveCompleted = true;
}
}
赞赏。 谢谢。
您将忽略ReceiveAsync
的返回值。 请注意文档 -有两种可能的行为,您必须检查返回值以区别它们:
如果I / O操作未决,则返回true。 操作完成后,将引发
e
参数上的SocketAsyncEventArgs.Completed
事件。如果I / O操作同步完成,则返回false。 在这种情况下,不会引发
e
参数上的SocketAsyncEventArgs.Completed
事件,并且在方法调用返回以检索操作结果之后,可以立即检查作为参数传递的e
对象。
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