为啥对 recv 的重叠调用会返回 ERROR_NO_MORE_ITEMS(259)？

Posted 2023-02-21

【中文标题】为啥对 recv 的重叠调用会返回 ERROR_NO_MORE_ITEMS(259)？

【英文标题】：Why would an Overlapped call to recv return ERROR_NO_MORE_ITEMS(259)?为什么对 recv 的重叠调用会返回 ERROR_NO_MORE_ITEMS(259)？

【发布时间】：2011-09-30 14:04:03

【问题描述】：

我使用 I/O 完成端口和 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调用 WSARecv 后，它会立即返回错误 259 (ERROR_NO_MORE_ITEMS)。

我想知道为什么系统用这个错误标记重叠事务，而不是让 recv 调用阻塞/等待传入数据。

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;

                

减少错误检查...

Recv-member-function 是 WSARecv-call 的简单包装器，它创建 WSABUF 和接收缓冲区本身（需要用户通过 freewsabuf 清理 - 只是提一下）...

【问题讨论】：

没什么意义，没什么可看的。请注意，等待肯定不能保证，重叠的调用可以立即完成。

你需要展示一些代码，最好是一个最小的可编译示例。请注意，即使您将重叠结构传递给 API 函数，操作仍然可以同步完成。

另外，您是否使用 WSAGetLastError（而不是 GetLastError）？

@Avakar WSAGetLastError 返回 0（无错误/成功）

【参考方案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 连接接收一小部分请求的垃圾会触发完成指示，并显示错误 ERROR_NO_MORE_ITEMS，这意味着没有什么比它已经拥有的要接收的了。