工作程式碼片段-epoll

測試的執行個體：

        int fd =  open("a.txt", 'r');        epoll_event ev;        int efd = epoll_create(1);        ev.events = EPOLLIN | EPOLLOUT;        ev.data.fd = fd;        epoll_ctl(efd, EPOLL_CTL_ADD, fd, &ev);        epoll_event evs[3];        int r = epoll_wait(efd, evs, 1, 0);        if(r == -1) {            std::cout << "error" << std::endl;        }        for(int i =0; i < 1; ++i) {            std::cout << " >>>"<< evs[i].data.fd << std::endl;            std::cout << "===" << evs[i].events << std::endl;            char buff[300];            read(fd, buff, 12);            std::cout << buff<< std::endl;        }        epoll_ctl(efd, EPOLL_CTL_MOD, fd, &ev);       int m = epoll_wait(efd, evs, 1, 0);       if(m == -1) {             std::cout << "error" << std::endl;        }       for(int i =0; i < 1; ++i) {           std::cout << " >>>"<< evs[i].data.fd << std::endl;           std::cout << "===" << evs[i].events << std::endl;       }       close(sfd);