https://blog.csdn.net/answer3y/article/details/48276687
https://blog.csdn.net/zmzsoftware/article/details/17356199
epoll EPOLLONESHOT
https://blog.csdn.net/linuxheik/article/details/73294658
https://www.cnblogs.com/charlesblc/p/5538363.html
https://blog.csdn.net/liuhengxiao/article/details/46911129