Question

我使用I / O-Completion端口和winsock套接字进行了一些测试。我遇到过，有时在我从连接接收数据然后在该套接字上再次相邻地调用WSARecv时，它会立即返回错误259（ERROR_NO_MORE_ITEMS）。

我想知道为什么系统会用这个错误标记重叠的事务，而不是让recv调用阻塞/等待传入的数据。

你知道这是什么意思吗？

我很高兴听到你的想法。

编辑：代码

do
    {
        OVERLAPPED* pOverlapped = nullptr;
        DWORD dwBytes = 0; ULONG_PTR ulKey = 0;

        //Dequeue a completion packet
        if(!m_pIOCP->GetCompletionStatus(&dwBytes, &ulKey, &pOverlapped, INFINITE))
            DebugBreak();

        //Evaluate
        switch(((MYOVERLAPPED*)pOverlapped)->WorkType)
        {
        case ACCEPT_OVERLAPPED_TYPE:
            {
                //cast
                ACCEPT_OVERLAPPED* pAccept = (ACCEPT_OVERLAPPED*)pOverlapped;

                //Associate the newly accepted connection with the IOCP
                if(!m_pIOCP->AssociateHandle((HANDLE)(pAccept->pSockClient)->operator SOCKET(), 1))
                {
                    //Association failed: close the socket and and delte the overlapped strucuture

                }

                //Call recv
                RECV_OVERLAPPED* pRecvAction = new RECV_OVERLAPPED;
                pRecvAction->pSockClient = pAccept->pSockClient;
                short s = (pRecvAction->pSockClient)->Recv(pRecvAction->strBuf, pRecvAction->pWSABuf, 10, pRecvAction);
                if(s == Inc::REMOTECONNECTION_CLOSED)
                {
                    //Error stuff
                }


                //Call accept again (create a new ACCEPT_OVERLAPPED to ensure overlapped being zeroed out)
                ACCEPT_OVERLAPPED *pNewAccept = new ACCEPT_OVERLAPPED;
                pNewAccept->pSockListen = pAccept->pSockListen;
                pNewAccept->pSockClient = new Inc::CSocket((pNewAccept->pSockListen)->Accept(nullptr, nullptr, pNewAccept));

                //delete the old overlapped struct
                delete pAccept;
            }
            break;
        case RECV_OVERLAPPED_TYPE:
            {
                RECV_OVERLAPPED* pOldRecvAction = (RECV_OVERLAPPED*)pOverlapped;
                if(!pOldRecvAction->InternalHigh)
                {
                    //Connection has been closed: delete the socket(implicitly closes the socket)
                    Inc::CSocket::freewsabuf(pOldRecvAction->pWSABuf);      //free the wsabuf
                    delete pOldRecvAction->pSockClient;
                }
                else
                {
                    //Call recv again (create a new RECV_OVERLAPPED)
                    RECV_OVERLAPPED* pNewRecvAction = new RECV_OVERLAPPED;
                    pNewRecvAction->pSockClient = pOldRecvAction->pSockClient;
                    short sRet2 = (pNewRecvAction->pSockClient)->Recv(pNewRecvAction->strBuf, pNewRecvAction->pWSABuf, 10, pNewRecvAction);



                    //Free the old wsabuf
                    Inc::CSocket::freewsabuf(pOldRecvAction->pWSABuf);
                    delete pOldRecvAction;

                }

剪切错误检查......

Recv-member-function是一个围绕WSARecv调用的简单包装器，它创建了WSABUF和接收缓冲区本身（需要用户通过freewsabuf清理 - 只需提及）......

Answer 1

看起来我发送的数据少于接收方请求的数据。但由于它是一个重叠操作，通过TCP连接接收一小块请求的串将触发完成指示，错误为ERROR_NO_MORE_ITEMS，这意味着没有什么比它已经拥有的更多了。

为什么对recv的重叠调用会返回ERROR_NO_MORE_ITEMS（259）？

1 个答案: