Modern Poller viewed as message queue

 Modern poller, including epoll, kqueue or vpp_vcl_epoll are message queues!

# Construtor

epoll: epoll_create() returns fd

kqueue: kqueue() return fd

vpp_vcl_epoll: created within struct vcl_worker, request for event_fd

# Notification

How do poller owner wait for the next message(s)?

epoll: epoll_wait()

kqueue: kevent(int kq, ..., struct kevent *eventlist,...)

vpp_vcl_epoll: vppcom_epoll_wait()

Advance: you can actually stack fd into another poller and wait.

# subscribe

epoll: epoll_ctl() to mutate the topics

kqueue: kevent(int kq, const struct kevent *changelist, ...)

vpp_vcl_epoll: vppcom_epoll_ctl()

# publish

epoll: linux kernel

kqueue: BSD kernel

vpp_vcl_epoll: struct vcl_worker_