libevent库源码学习-devpoll（/dev/poll）（ linux）

1.初始化
使用
fd = open(“/dev/poll”, flags, (mode_t)mode);获得文件描述符

2.增加事件
struct pollfd *events;
pwrite(fd, events,sizeof(struct pollfd) * eventsnum, 0) 直接往里边写

3.删除事件
使用 POLLREMOVE 事件，然后把这个时间用增加时间的方法写入/dev/poll，系统会自动将我们要删除的描述符时间删除


4.监听事件

struct dvpoll {
        struct pollfd *dp_fds;
        int dp_nfds;
        int dp_timeout;
    }

struct dvpoll dvp;
res = ioctl(devpollop->dpfd, DP_POLL, &dvp);返回事件发生的个数

用个for遍历一遍即可
for (i = 0; i < res; i++) {
int which = 0;
int what = dvp.dp_fds[i].revents;

if (what & POLLHUP)
what |= POLLIN | POLLOUT;
else if (what & POLLERR)
what |= POLLIN | POLLOUT;

if (what & POLLIN)
which |= EV_READ;
if (what & POLLOUT)
which |= EV_WRITE;


if (!which)
continue;
。。。
}