On Wed, Aug 6, 2025 at 6:46 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > "Unlike epoll descriptors, kqueue descriptors only transition from > readable to unreadable when kevent() is called and finds nothing, > after removing level-triggered conditions that have gone away. We > therefore need a dummy kevent() call after operations might have been > performed on the monitored sockets or timer_fd. Any event returned is > ignored here, but it also remains queued (being level-triggered) and > leaves the descriptor readable. This is a no-op for epoll > descriptors."
I really like this; I'm working it into the doc comment. > FWIW I re-read the kqueue paper's discussion of the goals of making > kqueue descriptors themselves monitorable/pollable, and it seems it > was mainly intended for hierarchies of kqueues, like your timer_fd, > with the specific aim of expressing priorities. It doesn't talk about > giving them to code that doesn't know it has a kqueue fd (the client) > and never calls kevent() and infers the events instead (libcurl). Interesting! It would be nice if they papered over this for us, but I guess that's water under the bridge. > s/signalled/signaled/ (= US spelling) in a couple of places. Ah. Will fix(?) or else lobby the dictionary companies. Thank you so much for the reviews! --Jacob
