raft算法中选主的流程用伪代码描述出来,包括任期和索引
时间: 2024-02-19 22:01:18 浏览: 57
基本算法的伪代码
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以下是Raft算法中选主的流程的伪代码:
```
1. 初始化
currentTerm = 0
votedFor = null
state = "follower"
electionTimeout = random(electionTimeoutMin, electionTimeoutMax)
2. 当follower接收到来自leader的心跳时:
reset electionTimeout
3. 当follower的electionTimeout时间到期时:
state = "candidate"
currentTerm += 1
votedFor = self
reset electionTimeout
send RequestVote RPCs to all other servers
4. 当收到其他server的RequestVote RPC时:
if request.term < currentTerm
return false
else if request.term > currentTerm
currentTerm = request.term
votedFor = null
state = "follower"
if (votedFor is null or votedFor == candidateId) and candidate's log is at least as up-to-date as receiver’s log
votedFor = candidateId
return true
else
return false
5. 当candidate获得majority的票数时:
state = "leader"
nextIndex[] = [index of the next log entry to send to each server]
matchIndex[] = [index of highest log entry known to be replicated on server]
6. 当leader需要发送日志时:
for each server in cluster
send AppendEntries RPC with log entries starting at nextIndex[server]
if successful
update nextIndex and matchIndex for server
else
decrement nextIndex for server
```
其中,`currentTerm` 表示当前的任期,`votedFor` 表示该任期中投票的候选人,`state` 表示当前节点的状态("follower"、"candidate" 或 "leader"),`electionTimeout` 表示选举超时时间。在第3步中,如果节点未在 `electionTimeout` 时间内接收到来自leader的心跳,就会转变为候选人("candidate"),并向其他节点发送投票请求。在第4步中,当收到其他server的RequestVote RPC时,节点会比较该节点的日志和自己的日志,如果该节点的日志比自己的日志新,就会投票给该节点。在第5步中,当候选人获得majority的票数时,就会成为leader,并开始发送日志。在第6步中,leader会不断发送日志,直到所有节点都同步了该日志。
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