c++ - Linux 上的异​​步套接字发送

Question

当在异步套接字上发送时返回 EAGAIN，这是否意味着:当前调用刚刚成功排队，或者由于系统仍在处理之前的发送而未执行任何操作？

提前谢谢你。

Answer 1

来自 man 2 send:

The socket is marked nonblocking and the requested operation would block. POSIX.1-2001 allows either error to be returned for this case, and does not require this constants [EAGAIN EWOULDBLOCK] to have the same value, so a portable application should check for both possibilities.

所以，我认为 EAGAIN 的意思是:小心，消息不适合发送缓冲区，此调用将在正常(阻塞)模式下被阻塞。使用select(2)判断是否可以发送更多数据。

附言实际上，看起来调用失败了，什么也没做。