Hi,
If you trigger the new optional NetBSD CI task, the oauthvalidator
tests implode[1]. Apparently that OS's kevent() doesn't like zero
relative timeouts for EVFILT_TIMER[2]. I see that you worked around
the same problem for Linux timerfd already by rounding 0 up to 1, so
we could just do the same here, and it passes with the attached. A
cute alternative, not tested, might be to put NOTE_ABSTIME into fflag
if timeout == 0 (then it's an absolute time in the past, which should
fire immediately).
But I'm curious, how hard would it be to do this ↓ instead and not
have that problem on any OS?
* There might be an optimization opportunity here: if timeout == 0, we
* could signal drive_request to immediately call
* curl_multi_socket_action, rather than returning all the way up the
* stack only to come right back. But it's not clear that the additional
* code complexity is worth it.
[1] https://cirrus-ci.com/task/6354435774873600
[2] https://github.com/NetBSD/src/blob/67c7c4658e77aa4534b6aac8c041d77097c5e722/sys/kern/kern_event.c#L1375
