0138f51f93
fd_done_recv() used to be useful with the FD cache because it used to allow to keep a file descriptor active in the poller without being marked as ready in the cache, saving it from ringing immediately, without incurring any system call. It was a way to make it yield to wait for new events leaving a bit of time for others. The only user left was the connection accepter (listen_accept()). We used to suspect that with the FD cache removal it had become totally useless since changing its readiness or not wouldn't change its status regarding the poller itself, which would be the only one deciding to report it again. Careful tests showed that it indeed has exactly zero effect nowadays, the syscall numbers are exactly the same with and without, including when enabling edge-triggered polling. Given that there's no more API available to manipulate it and that it was directly called as an optimization from listener_accept(), it's about time to remove it.