Calls epoll_ctl() using the current epoll file descriptor to modify the
registration of fd for events with obj as user data.
Creates the epoll_event_t instance passed to epoll_ctl() from events and
obj where data.obj is set to obj.
The current epoll file descriptor should have been sucessfully obtained
by create() or epoll_create1() and not already been closed, otherwise
epoll_ctl() will fail so that this method returns -1.
Calls epoll_ctl() using the current epoll file descriptor to modify the registration of fd for events with obj as user data.
Creates the epoll_event_t instance passed to epoll_ctl() from events and obj where data.obj is set to obj.
The current epoll file descriptor should have been sucessfully obtained by create() or epoll_create1() and not already been closed, otherwise epoll_ctl() will fail so that this method returns -1.