Raft

https://docs.qq.com/doc/DY0VxSkVGWHFYSlZJ
https://raft.github.io/raft.pdf
https://github.com/maemual/raft-zh_cn
https://github.com/gopherWxf/tinykv/blob/master/doc/TinyKv-Project2-PartA-RaftKV.md