IOCP之客户端及消息传递

上篇说到IOCP的精简实现，这篇来讲IOCP客户端和消息传递

在ConnectEx代码之前，CreateIoCompletionPort的第三个参数，把socket句柄+0x01000000作为传递

        sNew = ::WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, WSA_FLAG_OVERLAPPED);
        if (sNew != SOCKET_ERROR)
        {
            ::CreateIoCompletionPort((HANDLE)sNew, hCompletion, (DWORD)sNew+0x01000000, 0);
            ::bind(sNew, (sockaddr*)&Local, sizeof(Local));
            if (ConnectEx(sNew, (PSOCKADDR)&SSer, sizeof(SSer), NULL, 0, &dwRecv, &over) == FALSE)
            {
                if (::WSAGetLastError() != ERROR_IO_PENDING)
                {
                    printf("ConnectEx failed with error [%d]
", ::WSAGetLastError());
                }
            }
        }

工作线程接收到，ConnectEx异步处理结果时，通过GetQueuedCompletionStatus接收第三个参数，做响应的处理即可

char *cTmp = (char*)&SSoc;

::GetQueuedCompletionStatus(hCompletion, &dTmp,(LPDWORD)&SSoc, &OverLapped, WSA_INFINITE);

switch (cTmp[3])
{
    case 0x01:
    {
        cTmp[3] = 0;
        .....处理
    }
    break;
}

后续WSASend、WSARecv等可以使用PostQueuedCompletionStatus方式调用即可，当然消息可以自定义，CON：0x01、Send：0x02，Recv：0x03、closesocket：0x04等等,要注意后面要补齐6个0，这样就实现了SOCKET句柄带消息类型传递。

PostQueuedCompletionStatus(hCompletion, DWORD(0), (DWORD)sNew+0x01000000, NULL);

甚至还可以用WSAAsyncSelect这货的PostThreadMessage传递MSG，用之前要修改注册表设置最大消息上限。

Windows Registry Editor Version 5.00

;增加消息上限
[HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWindows]
"USERPostMessageLimit"=dword:000FFFFF