how to use epoll with data->ptr, instead of data.fd?

Question

I'm writing an application using epoll and large amount of fd's. in order to improve the searches of fd to application relevant DB, I want to pass to epoll application info, such as index in DB array. I thought of using the data->ptr (epoll_data_t --> *ptr), as far as I understood, I can give pointer that holds the fd and private information from the application layer, but couldn't found any documents or examples.

I found this post, which seems to be relevant, but there is no implementation example... How to use epoll_event data.ptr

Thanks

Answer 1

You can put whatever you want in data. It's not used by epoll itself, it just returns it when the event occurs on the fd specified in the argument list.