彻底解决关于CSocket类的Receive超时的问题

网上有一些相关的东西，但经自己测试后，并没有实现功能。OnMessagePending没有监测到WM_TIMER消息。

然后我对类进行了调整，一来使得封装更好，二来外部调用基本不用做任何变化，三来希望能使OnMessagePending能够起作用。

其实修改很简单，就是将SetTimeOut和KillTimeOut都修改为私有函数，并重载CSocket基类的Receive和Send函数，在收发前后启动和关闭定时器。

注意：原文中 if(::PeekMessage(&msg, NULL, WM_TIMER, WM_TIMER, PM_NOREMOVE))语句并没有实现获取WM_TIMER消息的功能，后来，经过网上查找资料

PM_NOREMOVE 修改为PM_REMOVE

头文件 ClientSocket.h

#pragma once

#include "afxwin.h"

#include <afxsock.h>  

// CClientSocket 命令目标

class CTimeOutSocket : public CSocket

{
// Attributes

public:
CTimeOutSocket();
virtual~CTimeOutSocket();

public:
virtual BOOL OnMessagePending();
virtual int Receive(void* lpBuf, int nBufLen, int nFlags =0);
virtual int Send(const void* lpBuf, int nBufLen, int nFlags =0);
virtual int SendTo(const void* lpBuf, int nBufLen,UINT nHostPort, LPCTSTR lpszHostAddress , int nFlags);
virtual int ReceiveFrom(void* lpBuf, int nBufLen,CString& rSocketAddress, UINT& rSocketPort, int nFlags);
int m_nTimerID;

private:
BOOL KillTimeOut();
BOOL SetTimeOut(int nTimeOut);

};

以下为ClientSocket.c文件

#include "stdafx.h"

#include "ClientSocket.h"

CTimeOutSocket::CTimeOutSocket()

{

}

CTimeOutSocket::~CTimeOutSocket()

{

}

BOOL CTimeOutSocket::OnMessagePending() 

{
MSG msg;
if(::PeekMessage(&msg, NULL, WM_TIMER, WM_TIMER, PM_REMOVE))//PM_NOREMOVE
{
if (msg.wParam == (UINT) m_nTimerID)
{
// Remove the message and call CancelBlockingCall.
::PeekMessage(&msg, NULL, WM_TIMER, WM_TIMER, PM_REMOVE);
CancelBlockingCall();
return FALSE;  // No need for idle time processing.
};
};
return CSocket::OnMessagePending();

}

int CTimeOutSocket::Receive(void* lpBuf, int nBufLen, int nFlags) 

{
SetTimeOut(5000);
int nRecv = CSocket::Receive(lpBuf, nBufLen, nFlags);
KillTimeOut();
return nRecv;

}

int CTimeOutSocket::ReceiveFrom(void* lpBuf, int nBufLen,CString& rSocketAddress, UINT& rSocketPort, int nFlags)

{
SetTimeOut(10000);
int nRecv = CSocket::ReceiveFrom(lpBuf,  nBufLen, rSocketAddress, rSocketPort,nFlags);
KillTimeOut();
return nRecv;

}

int CTimeOutSocket::Send(const void* lpBuf, int nBufLen, int nFlags) 

{
SetTimeOut(10000);
int nSend = CSocket::Send(lpBuf, nBufLen, nFlags);
KillTimeOut();
return nSend; 

}

int CTimeOutSocket::SendTo(const void* lpBuf, int nBufLen,UINT nHostPort, LPCTSTR lpszHostAddress, int nFlags )

{
SetTimeOut(10000);
int nSend = CSocket::SendTo(lpBuf, nBufLen, nHostPort,lpszHostAddress,nFlags);
KillTimeOut();
return nSend; 

}

BOOL CTimeOutSocket::SetTimeOut(int nTimeOut)

{
m_nTimerID = SetTimer(NULL,0,nTimeOut,NULL);
return m_nTimerID;

}

BOOL CTimeOutSocket::KillTimeOut()

{
return KillTimer(NULL,m_nTimerID);

}

经过修改的代码，运行后OnMessagePending得到了WM_TIMER消息，正确解决了Receive的阻塞问题，同时我只需将原来的CSocket对象改为CTimeOutSocket对象就可以了，以上代码经测试可直接使用。