How to monitor an eventfd in the main thread of uWebSockets?

[cn-xuezha]

Ubuntu:
How to monitor an eventfd in the main thread of uWebSockets?

[uNetworkingAB]

That's a very good question and precisely the right approach for many integrations. Many people ask "how can I do this and that from another thread" <- that's the wrong approach. Don't mix threads, integrate things with the event loop (like you ask for).

uWebSockets is standard C++, it has no idea of FDs. uSockets does, and it's the eventing part https://github.com/uNetworking/uSockets/blob/master/src/eventing/epoll_kqueue.c

You can get the us_loop_t ptr by doing uWS::Loop::get() and casting it to us_loop_t ptr.

Then you either use us_internal_async (which are eventfds), or you simply use uWS::Loop::defer or us_loop_wakeup() or us_poll_t

You could also just link with libuv and use libuv's uv_async_t. I don't remember the exact details, but you can look at that file. Paste it into AI and ask there. Maybe we need to expose these us_internal_async_t things because those are already done with eventfds and we use those for uWS::Loop::defer already

[uNetworkingAB]

Ah shit, easiest is probably to link with libuv and use uv_async_t.

[uNetworkingAB]

Generic polling with a callback should really have been added to uSockets. The feature is already supported it just needs a documented interface and function to init with a callback.