c++ - who assigns event/interface id for handling in epoll_wait() -

this question bugs me long time. want know, in case of event polling mechanism. when have code in have 3 fds poll , have assigned each interface type each fd event identified. handling done using epoll_create(), reception of events using epoll_wait().

say: 3 fds.  1 timer, 1 ipc, 1 mqtt -> creation using epoll_create 

but question assigns event id or interface id external event category of events , respective interface internal.

please let me know if question clear or not.

i have found answer.

say there 3 fds created: 1 timer, 1 ipc & 1 mqtt. when these created subsequent interfaces assigned each interface fd inturn added poll fd. any event happening on each interface id read poll fd , interface happened known.

that's how known interface event meant. not case external module assigns epoll interface id, rather handled internally.