Raft算法中选主的流程用伪代码描述出来

Raft算法中的Leader选举流程可以用以下伪代码来描述：

1. 初始化状态
   currentTerm = 0
   votedFor = null
   state = follower

2. 当收到来自candidate的请求时，执行以下操作：
   if (request.term < currentTerm) {
       return false
   } 
   if (request.term > currentTerm) {
       currentTerm = request.term
       votedFor = null
   }
   if (votedFor is null or votedFor = request.candidateId) {
       grant vote to candidate
       votedFor = request.candidateId
       reset election timer
       state = follower
       return true
   }

3. 当收到来自leader的请求时，执行以下操作：
   if (request.term < currentTerm) {
       return false
   }
   currentTerm = request.term
   leaderId = request.leaderId
   reset election timer
   state = follower
   return true

4. 检查选举超时
   if (election timer expires) {
       start new election
   }

5. 发起新的选举
   currentTerm++
   votedFor = self
   state = candidate
   send RequestVote RPCs to all other servers
   reset election timer

6. 当收到来自其他服务器的投票请求时，执行以下操作：
   if (request.term < currentTerm) {
       return false
   }
   if (votedFor is null or votedFor = request.candidateId) {
       grant vote to candidate
       votedFor = request.candidateId
       reset election timer
       state = follower
       return true
   }
   return false

以上伪代码描述了Raft算法中选主的流程，其中包括了follower、candidate和leader三种状态的转换，以及投票和超时等情况的处理。