- A listening socket blocked on accept() can be unblocked by calling shutdown(socket_fd, SHUT_RD) on Linux. On Mac, calling shutdown(socket_fd, SHUT_RD) on a listening socket that is blocked on accept() will return an error ENOTCONN. To unblock a listening socket blocked on accept() on Mac requires calling close(socket_fd), which will cause the blocking accept() call to return an error EBADF.
Therefore, in order to unblock a socket on accept() on both Mac/Linux, shutdown() should not be relied on. Rather, an async cancellation scheme (such as cancellation tokens in .NET) should be used instead to unblock the call to accept().
- When a socket is instantiated and subsequently registered to epoll, or when a socket is shut down (via. shutdown() or setsockopt(SO_LINGER)) on Linux, epoll will be notified with EPOLLHUP on the socket. On Mac, kqueue will only notify when a socket is shut down (via. shutdown() or setsockopt(SO_LINGER)) by sending a EV_EOF notification on filters EVFILT_READ, and EVFILT_WRITE.
Thi
