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WinSock Tips

1. WSAEWOULDBLOCK 错误说明

在非锁定套接字上

函数名	说明
WSAAccept, accept	应用程序没有收到连接请求，再次调用，便可检查连接情况
closesocket	大多数情况下，这个错误意味着已随SO_LINGER选项一道调用了 setsockopt，而且已设定了一个非零的超时值
WSAConnect, connect	应用程序已初始化，再次调用，便可检查是否完成
WSARecv,recv WSARecvFrom, recvfrom	没有收到数据，销后再次检查
WSASend, send WSASendTo, sendto	外出数据无缓冲区可用，销后再试

2. FD_WRITE 触发条件

只有在三种条件下，才会发出 FD_WRITE 通知
. connect, WSAConnect ，一个套接字首次建立了连接
. accept, WSAAccept, 套接字被接受以后
. send, WSASend, sendto, WSASendTo操作失败，返回了 WSAEWOULDBLOCK 错误，而且缓冲
再次变得可用时

[@more@]If no incoming data is available at the socket, the recv call blocks and waits for data to arrive according to the blocking rules defined for WSARecv with the MSG_PARTIAL flag not set unless the socket is nonblocking. In this case, a value of SOCKET_ERROR is returned with the error code set to WSAEWOULDBLOCK. The select, WSAAsyncSelect, or WSAEventSelect functions can be used to determine when more data arrives.

ITPub博客

(zz)WSAEWOULDBLOCK 与 FD_WRITE 说明

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