下面代码是对I/O复用接口函数的基本使用。

回顾上篇文章：事件监控管理模块

这个模块是将触发事件的描述符，给到外面，让外面去做对应的处理。

#define MAX_EPOLLEVENTS 1024
class Poller {private:int _epfd;struct epoll_event _evs[MAX_EPOLLEVENTS];std::unordered_map<int, Channel *> _channels;private://对epoll的直接操作void Update(Channel *channel, int op) {// int epoll_ctl(int epfd, int op,  int fd,  struct epoll_event *ev);int fd = channel->Fd();struct epoll_event ev;ev.data.fd = fd;ev.events = channel->Events();int ret = epoll_ctl(_epfd, op, fd, &ev);if (ret < 0) {ERR_LOG("EPOLLCTL FAILED!");}return;}//判断一个Channel是否已经添加了事件监控bool HasChannel(Channel *channel) {auto it = _channels.find(channel->Fd());if (it == _channels.end()) {return false;}return true;}public:Poller() {_epfd = epoll_create(MAX_EPOLLEVENTS);if (_epfd < 0) {ERR_LOG("EPOLL CREATE FAILED!!");abort();//退出程序}}//添加或修改监控事件void UpdateEvent(Channel *channel) {bool ret = HasChannel(channel);if (ret == false) {//不存在则添加_channels.insert(std::make_pair(channel->Fd(), channel));return Update(channel, EPOLL_CTL_ADD);}return Update(channel, EPOLL_CTL_MOD);}//移除监控void RemoveEvent(Channel *channel) {auto it = _channels.find(channel->Fd());if (it != _channels.end()) {_channels.erase(it);}Update(channel, EPOLL_CTL_DEL);}//开始监控，返回活跃连接void Poll(std::vector<Channel*> *active) {// int epoll_wait(int epfd, struct epoll_event *evs, int maxevents, int timeout)int nfds = epoll_wait(_epfd, _evs, MAX_EPOLLEVENTS, -1);if (nfds < 0) {if (errno == EINTR) {return ;}ERR_LOG("EPOLL WAIT ERROR:%s\n", strerror(errno));abort();//退出程序}for (int i = 0; i < nfds; i++) {auto it = _channels.find(_evs[i].data.fd);assert(it != _channels.end());it->second->SetREvents(_evs[i].events);//设置实际就绪的事件active->push_back(it->second);}return;}
};