send和recv非阻塞时如何正确处理WSAEWOULDBLOCK和设置超时

RCSocketResult RCAsyncSocket::Send(const char* pBuff, int32_t nLen, int32_t& nLenSent, DWORD dwTimeOut)
{	
    m_nLastError = 0;
    int32_t bytesSent = 0;
    int32_t sendLeft = nLen;
    nLenSent = 0;
    HANDLE arrHandles[3];

    int32_t waitCount = (m_breakEvent != NULL) ? 3 : 2;
    arrHandles[0] = m_eventNet.GetEvent();
    arrHandles[1] = m_eventStop.GetEvent();
    arrHandles[2] = m_breakEvent;
    do 
    {
        bytesSent = send(m_hSocket, pBuff, sendLeft, 0);;

        if (bytesSent == SOCKET_ERROR)
        {  
            m_nLastError = WSAGetLastError();
            if (m_nLastError != WSAEWOULDBLOCK)
            {
                //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Send Error 01 with error code %d"), m_nLastError);
                return RC_SOCKET_SOCKERR;
            }

            bytesSent = 0;

            DWORD dwWaitRes = WaitForMultipleObjects(waitCount, arrHandles, FALSE, dwTimeOut); 

            if (dwWaitRes == WAIT_OBJECT_0 + 1 || dwWaitRes == WAIT_OBJECT_0 + 2)
            {
                m_nLastError = WSAGetLastError();
                //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Send Error 02 Abort"));
                return RC_SOCKET_ABORTED;
            }
            else if (dwWaitRes != WAIT_OBJECT_0)
            {
                m_nLastError = WSAGetLastError();
                //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Send Error 03 TimeOut"));
                return RC_SOCKET_TIMEDOUT;
            }

            WSANETWORKEVENTS netEvents;
            if (WSAEnumNetworkEvents(m_hSocket, m_eventNet.GetEvent(), &netEvents) != 0)
            {
                m_nLastError = WSAGetLastError();
                //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Send Error 04 WSAEnumNetworkEvents error with ErrorCode %d"), m_nLastError);
                return RC_SOCKET_SOCKERR;
            }


            if ((netEvents.lNetworkEvents & FD_CLOSE) == FD_CLOSE)
            {
                m_nLastError = WSAGetLastError();
                //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Send Error 05 FD_CLOSE"));
                return RC_SOCKET_ABORTED;
            }

            if ((netEvents.lNetworkEvents & FD_WRITE) == FD_WRITE)
            {
                if (netEvents.iErrorCode[FD_WRITE_BIT] != 0)
                {
                    m_nLastError = WSAGetLastError();
                    //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Send Error 06 FD_WRITE_BIT error"));
                    return RC_SOCKET_SOCKERR;
                }                   
            }            
        }  
        nLenSent += bytesSent;
        pBuff += bytesSent;
        sendLeft -= bytesSent;
    }
    while (sendLeft > 0);

    return RC_SOCKET_SUCCESS;   
}

RCSocketResult RCAsyncSocket::Recv(char* pBuff, int32_t nLen, int32_t& nLenReceived, DWORD dwTimeOut)
{
    m_nLastError = 0;
    HANDLE arrHandles[3];
    int32_t waitCount = (m_breakEvent != NULL) ? 3 : 2;
    arrHandles[0] = m_eventNet.GetEvent();
    arrHandles[1] = m_eventStop.GetEvent();
    arrHandles[2] = m_breakEvent;
    int32_t recvLeft = nLen;
    int32_t bytesRecv = 0;
    nLenReceived = 0;
    do
    {
        bytesRecv = ::recv(m_hSocket, pBuff, recvLeft, 0);
        if (bytesRecv == 0)
        {
            m_nLastError = WSAGetLastError();
            WRITE_ERROR_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 01 connection closed"));
            return RC_SOCKET_ABORTED;
        }
        else if(bytesRecv == SOCKET_ERROR)
        {   
            m_nLastError = WSAGetLastError();
            if (m_nLastError != WSAEWOULDBLOCK)            
            {                
               WRITE_ERROR_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 02 with error code %d"), m_nLastError);
               return RC_SOCKET_SOCKERR;
            }            
            bytesRecv = 0;
            DWORD dwWaitRes = WaitForMultipleObjects(waitCount, arrHandles, FALSE, dwTimeOut);
            if (dwWaitRes == WAIT_OBJECT_0 + 1 || dwWaitRes == WAIT_OBJECT_0 + 2)
            {
                WRITE_ERROR_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 03 connection Abort"));
                return RC_SOCKET_ABORTED;
            }
            else if (dwWaitRes != WAIT_OBJECT_0)
            {
               WRITE_ERROR_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 04 recv timeout"));
                return RC_SOCKET_TIMEDOUT;
            }

            WSANETWORKEVENTS myNetEvents;
            if (::WSAEnumNetworkEvents(m_hSocket, m_eventNet.GetEvent(), &myNetEvents) != 0)
            {
                WRITE_ERROR_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 05 with error code %d"), m_nLastError);
                m_nLastError = WSAGetLastError();
                return RC_SOCKET_SOCKERR;
            }

            if ((myNetEvents.lNetworkEvents & FD_READ) == FD_READ)   
            {
                if (myNetEvents.iErrorCode[FD_READ_BIT] != 0)
                {
                    m_nLastError = WSAGetLastError();
                    WRITE_ERROR_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 06 with error FD_READ_BIT %d"), myNetEvents.iErrorCode[FD_READ_BIT]);
                    return RC_SOCKET_SOCKERR;
                }
                continue;
            }
            if ((myNetEvents.lNetworkEvents & FD_CLOSE) == FD_CLOSE)
            {
                //WRITE_DEBUG_LOG(RCMOBILE_MODDULE_CONNECT_GUID, _T(" RCAsyncSocket::Recv Error 07 connection receive FD_CLOSE"));
                continue;
            }
        }
        nLenReceived += bytesRecv;
        recvLeft -= bytesRecv;
        pBuff += bytesRecv;
    }  
    while (recvLeft > 0);
    return RC_SOCKET_SUCCESS;
}

关键在于，错误码是WSAEWOULDBLOCK时，设置当前发送或者接受的字节数为0，然后用

WSAEnumNetworkEvents

检测网络事件。