说明：  fast_tcp的源代码加上了自己对它的中文注释,由于关于这方面的资料比较少所以想把自己做的一些东西拿出来,让同样学TCP
(The source code of fast_tcp has added its own Chinese annotation to it, because there is little information about it, I would like to take out some of the things I do, so that I can learn from TCP as well.)