[libevent]event_set()

voidevent_set(struct event *ev, int fd, short events,  void (*callback)(int, short, void *), void *arg){/* Take the current base - caller needs to set the real base later */ev->ev_base = current_base;//current_base为一个全局变量，生成一个event_base默认会被赋值给它，默认的event会与这个全局变量关联</span>ev->ev_callback = callback;ev->ev_arg = arg;ev->ev_fd = fd;ev->ev_events = events;ev->ev_res = 0;ev->ev_flags = EVLIST_INIT;ev->ev_ncalls = 0;ev->ev_pncalls = NULL;min_heap_elem_init(ev);初始化min_heap_idx为-1/* by default, we put new events into the middle priority */if(current_base)ev->ev_pri = current_base->nactivequeues/2;//默认event的优先级是最高优先级的一半}