libevent使用event来封装网络事件回调，参数、fd。。。等1些信息,函数很简单
void
event_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; //设置成默许的current_base,如果
ev->ev_callback = callback; //设置事件回调callback;
ev->ev_arg = arg; //设置参数
ev->ev_fd = fd; //设置句柄
ev->ev_events = events; //设置当前的事件
/*
* EV_TIMEOUT 0x01
* EV_READ 0x02
* EV_WRITE 0x04
* EV_SIGNAL 0x08
* EV_PERSIST 0x10
*/
ev->ev_res = 0; //记录当前激活事件的类型
ev->ev_flags = EVLIST_INIT; //设置事件标志，用于表示当前的事件处于甚么阶段
/*
* EVLIST_TIMEOUT 0x01 //代表event在time堆中
* EVLIST_INSERTED 0x02 //代表event在已注册时间链表中
* EVLIST_SIGNAL 0x04 //未见使用
* EVLIST_ACTIVE 0x08 //代表event在激活链表中
* EVLIST_INTERNAL 0x10 //内部使用标记
* EVLIST_INIT 0x80 //代表event已被初始化
*/
ev->ev_ncalls = 0; //代表callback被履行多少次
ev->ev_pncalls = NULL; //指向ev_ncallsor指向NULL
min_heap_elem_init(ev); //初始化时间堆中的索引值
/* by default, we put new events into the middle priority */
if(current_base)
ev->ev_pri = current_base->nactivequeues/2;//设置事件的权限为中间权限为默许值
}
使用libevent在多线程中，就会存在多个event_base来进行reactor事件模型, 就需要对struct event设置所归属的event_base
调用的函数以下：
int
event_base_set(struct event_base *base, struct event *ev)
{
/* Only innocent events may be assigned to a different base */
if (ev->ev_flags != EVLIST_INIT)//仅仅处在初始化中的事件对象才可以设置base,用于更新ev_base
return (⑴);
ev->ev_base = base;
ev->ev_pri = base->nactivequeues/2;
return (0);
}
这样当每一个线程都存在1个event_base的时候，那末就能够根据event所属的线程来设置当前的event_base,
如果不设置event_base而使用默许,那末会使用current_base,current_base设置成最后1个创建的event_base对象
设置事件权限，这个函数1般都是刚创建完event_base的使用，由于它使用的是current_base
int
event_priority_init(int npriorities)
{
return event_base_priority_init(current_base, npriorities);
}
//重新设置event_base权限，1维是最高的。。。
int
event_base_priority_init(struct event_base *base, int npriorities)
{
int i;
if (base->event_count_active)
return (⑴);
if (base->nactivequeues && npriorities != base->nactivequeues) {
for (i = 0; i < base->nactivequeues; ++i) {
free(base->activequeues[i]);
}
free(base->activequeues);
}
/* Allocate our priority queues */
base->nactivequeues = npriorities;
base->activequeues = (struct event_list **)calloc(base->nactivequeues,
npriorities * sizeof(struct event_list *));
if (base->activequeues == NULL)
event_err(1, "%s: calloc", __func__);
for (i = 0; i < base->nactivequeues; ++i) {
base->activequeues[i] = malloc(sizeof(struct event_list));
if (base->activequeues[i] == NULL)
event_err(1, "%s: malloc", __func__);
TAILQ_INIT(base->activequeues[i]);
}
return (0);
}
libeven 全部源码分析和sample都在我的 githup