You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
192 lines
5.2 KiB
192 lines
5.2 KiB
package nodes
|
|
|
|
import (
|
|
"math/rand"
|
|
"strconv"
|
|
"sync"
|
|
"time"
|
|
|
|
"go.uber.org/zap"
|
|
)
|
|
|
|
type RequestVoteArgs struct {
|
|
Term int // 候选人的当前任期
|
|
CandidateId string // 候选人 ID
|
|
LastLogIndex int // 候选人最后一条日志的索引
|
|
LastLogTerm int // 候选人最后一条日志的任期
|
|
}
|
|
|
|
type RequestVoteReply struct {
|
|
Term int // 当前节点的最新任期
|
|
VoteGranted bool // 是否同意投票
|
|
}
|
|
|
|
func (n *Node) startElection() {
|
|
n.Mu.Lock()
|
|
defer n.Mu.Unlock()
|
|
// 增加当前任期，转换为 Candidate
|
|
n.CurrTerm++
|
|
n.State = Candidate
|
|
n.VotedFor = n.SelfId // 自己投自己
|
|
n.Storage.SetTermAndVote(n.CurrTerm, n.VotedFor)
|
|
|
|
log.Sugar().Infof("[%s] 开始选举，当前任期: %d", n.SelfId, n.CurrTerm)
|
|
|
|
// 重新设置选举超时，防止重复选举
|
|
n.resetElectionTimer()
|
|
|
|
// 构造 RequestVote 请求
|
|
var lastLogIndex int
|
|
var lastLogTerm int
|
|
|
|
if len(n.Log) == 0 {
|
|
lastLogIndex = 0
|
|
lastLogTerm = 0 // 论文中定义，空日志时 Term 设为 0
|
|
} else {
|
|
lastLogIndex = len(n.Log) - 1
|
|
lastLogTerm = n.Log[lastLogIndex].Term
|
|
}
|
|
args := RequestVoteArgs{
|
|
Term: n.CurrTerm,
|
|
CandidateId: n.SelfId,
|
|
LastLogIndex: lastLogIndex,
|
|
LastLogTerm: lastLogTerm,
|
|
}
|
|
|
|
// 并行向其他节点发送请求投票
|
|
var Mu sync.Mutex
|
|
totalNodes := len(n.Nodes)
|
|
grantedVotes := 1 // 自己的票
|
|
|
|
for _, peerId := range n.Nodes {
|
|
go func(peerId string) {
|
|
reply := RequestVoteReply{}
|
|
if n.sendRequestVote(peerId, &args, &reply) {
|
|
Mu.Lock()
|
|
|
|
if reply.Term > n.CurrTerm {
|
|
// 发现更高任期，回退为 Follower
|
|
log.Sugar().Infof("[%s] 发现更高的 Term (%d)，回退为 Follower", n.SelfId, reply.Term)
|
|
n.CurrTerm = reply.Term
|
|
n.State = Follower
|
|
n.VotedFor = ""
|
|
n.Storage.SetTermAndVote(n.CurrTerm, n.VotedFor)
|
|
n.resetElectionTimer()
|
|
Mu.Unlock()
|
|
return
|
|
}
|
|
|
|
if reply.VoteGranted {
|
|
grantedVotes++
|
|
}
|
|
|
|
if grantedVotes == totalNodes / 2 + 1 {
|
|
n.State = Leader
|
|
log.Sugar().Infof("[%s] 当选 Leader!", n.SelfId)
|
|
n.initLeaderState()
|
|
}
|
|
|
|
Mu.Unlock()
|
|
}
|
|
}(peerId)
|
|
}
|
|
|
|
// 等待选举结果
|
|
time.Sleep(300 * time.Millisecond)
|
|
Mu.Lock()
|
|
if n.State == Candidate {
|
|
log.Sugar().Infof("[%s] 选举超时，重新发起选举", n.SelfId)
|
|
// n.State = Follower 这里不修改，如果appendentries收到term合理的心跳，再变回follower
|
|
n.resetElectionTimer()
|
|
}
|
|
Mu.Unlock()
|
|
}
|
|
|
|
func (node *Node) sendRequestVote(peerId string, args *RequestVoteArgs, reply *RequestVoteReply) bool {
|
|
log.Sugar().Infof("[%s] 请求 [%s] 投票", node.SelfId, peerId)
|
|
client, err := node.Transport.DialHTTPWithTimeout("tcp", node.SelfId, peerId)
|
|
if err != nil {
|
|
log.Error("[" + node.SelfId + "]dialing [" + peerId + "] fail: ", zap.Error(err))
|
|
return false
|
|
}
|
|
|
|
defer func(client ClientInterface) {
|
|
err := client.Close()
|
|
if err != nil {
|
|
log.Error("client close err: ", zap.Error(err))
|
|
}
|
|
}(client)
|
|
|
|
callErr := node.Transport.CallWithTimeout(client, "Node.RequestVote", args, reply) // RPC
|
|
if callErr != nil {
|
|
log.Error("[" + node.SelfId + "]calling [" + peerId + "] fail: ", zap.Error(callErr))
|
|
}
|
|
return callErr == nil
|
|
}
|
|
|
|
func (n *Node) RequestVote(args *RequestVoteArgs, reply *RequestVoteReply) error {
|
|
n.Mu.Lock()
|
|
defer n.Mu.Unlock()
|
|
// 如果候选人的任期小于当前任期，则拒绝投票
|
|
if args.Term < n.CurrTerm {
|
|
reply.Term = n.CurrTerm
|
|
reply.VoteGranted = false
|
|
return nil
|
|
}
|
|
|
|
// 如果请求的 Term 更高，则更新当前 Term 并回退为 Follower
|
|
if args.Term > n.CurrTerm {
|
|
n.CurrTerm = args.Term
|
|
n.State = Follower
|
|
n.VotedFor = ""
|
|
n.resetElectionTimer() // 重新设置选举超时
|
|
}
|
|
|
|
// 检查是否已经投过票，且是否投给了同一个候选人
|
|
if n.VotedFor == "" || n.VotedFor == args.CandidateId {
|
|
// 检查日志是否足够新
|
|
var lastLogIndex int
|
|
var lastLogTerm int
|
|
|
|
if len(n.Log) == 0 {
|
|
lastLogIndex = -1
|
|
lastLogTerm = 0
|
|
} else {
|
|
lastLogIndex = len(n.Log) - 1
|
|
lastLogTerm = n.Log[lastLogIndex].Term
|
|
}
|
|
|
|
if args.LastLogTerm > lastLogTerm ||
|
|
(args.LastLogTerm == lastLogTerm && args.LastLogIndex >= lastLogIndex) {
|
|
// 够新就投票给候选人
|
|
n.VotedFor = args.CandidateId
|
|
log.Sugar().Infof("在term(%s), [%s]投票给[%s]", strconv.Itoa(n.CurrTerm), n.SelfId, n.VotedFor)
|
|
reply.VoteGranted = true
|
|
n.resetElectionTimer()
|
|
} else {
|
|
reply.VoteGranted = false
|
|
}
|
|
} else {
|
|
reply.VoteGranted = false
|
|
}
|
|
|
|
n.Storage.SetTermAndVote(n.CurrTerm, n.VotedFor)
|
|
reply.Term = n.CurrTerm
|
|
return nil
|
|
}
|
|
|
|
// follower 500-1000ms内没收到appendentries心跳，就变成candidate发起选举
|
|
func (node *Node) resetElectionTimer() {
|
|
if node.ElectionTimer == nil {
|
|
node.ElectionTimer = time.NewTimer(time.Duration(500+rand.Intn(500)) * time.Millisecond)
|
|
go func() {
|
|
for {
|
|
<-node.ElectionTimer.C
|
|
node.startElection()
|
|
}
|
|
}()
|
|
} else {
|
|
node.ElectionTimer.Stop()
|
|
node.ElectionTimer.Reset(time.Duration(500+rand.Intn(500)) * time.Millisecond)
|
|
}
|
|
}
|