B站图文讲解，必看: https://www.bilibili.com/video/BV1yJ411P76f?from=search&seid=8328232223355833905
raft: https://blog.csdn.net/bandaoyu/article/details/108907388
zab:
https://www.sohu.com/a/304145871_120103006
https://blog.csdn.net/fu123123fu/article/details/81208847