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raft.go
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raft.go
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package raft
import (
"errors"
"log"
"net"
"os"
)
type LogType uint8
// 日志数据类型: 普通命令、新增节点、删除节点
const (
LOGCOMMAND LogType = iota
ADDSERVER
REMOVESERVER
)
// 日志数据
type LogEntry struct {
Index int // 索引
Term int // 当前日志所在的任期
Type LogType
Date []byte // 具体的指令数据
}
// 节点状态
type State int
const(
FOLLOWER State = iota
CANDIDATE
LEADER
)
type RaftNode struct {
// 当前状态
state State
// endpoint
config *RaftConfig
// 当前Leader的地址
leader string
// 收到的票数
voteCount int
// 当前Term
currentTerm int
// 给谁投票
votedFor string
// 提交日志的最高索引
commitIndex int
commitTerm int
lastApplied int
// 用于随机选举超时接收信号
toCh chan int
// 用于传输RPC
rpcCh chan *RaftRPC
// 用于client数据传输
reqCh chan interface{}
conn net.Conn
// 日志
Log []*LogEntry
leaderState *LeaderState
// 用于记录
logger *log.Logger
}
type LeaderState struct {
commitCh chan interface{}
// 存放follower节点最高log index
replicatedIndex map[string]int
}
func newLeaderState(members []string) *LeaderState {
ls := &LeaderState{
commitCh: make(chan interface{}, 1),
replicatedIndex: make(map[string]int),
}
for _, member := range members {
ls.replicatedIndex[member] = 0
}
return ls
}
// 初始化
func initRaft(config *RaftConfig) *RaftNode {
ls := newLeaderState(config.members)
r := &RaftNode{
state: FOLLOWER,
config: config,
logger: log.New(os.Stdout, "", log.LstdFlags),
toCh: make(chan int, 1),
rpcCh: make(chan *RaftRPC, 1),
leaderState: ls,
Log: []*LogEntry{},
}
return r
}
// 该节点以FOLLOWER状态运行,直到状态发生变化
func (r *RaftNode) runFollower() error {
go randomTimeout(r.toCh)
r.logger.Printf("[INFO] %s running as follower", r.config.addr)
for {
select {
case to := <- r.toCh:
if to == TimeRunOut{
log.Printf("时间用完了,转变为candidate")
r.state = CANDIDATE
r.currentTerm += 1
}
case rpc := <- r.rpcCh:
r.handleRPC(rpc)
}
}
}
// 该节点以CANDIDATE状态运行,直到状态发生变化
func (r *RaftNode) runCandidate() {
r.voteCount = 1
electionTimeout := 0
r.votedFor = r.config.addr
majority := len(r.config.members) / 2
for _, member := range r.config.members {
go r.SendRequestVote(member)
}
// read from rpcCh until majority is achieved
// if gets AppendEntries or VoteReq with > term revert to follower
// else keep counting votes
for r.state == CANDIDATE {
go randomTimeout(r.toCh)
select {
case rpc := <-r.rpcCh:
r.logger.Printf("[INFO] candidate received rpc")
r.handleRPC(rpc)
if r.state != CANDIDATE {
return
}
case _ = <-r.toCh:
r.logger.Printf("[INFO] %s received %d votes", r.config.addr, r.voteCount)
electionTimeout += 1
go randomTimeout(r.toCh)
}
// 转变为Leader
if r.voteCount > majority {
r.logger.Printf("[LEADER] taking power %s", r.config.addr)
r.state = LEADER
return
}
// 当前term未选出,重新开始选
if electionTimeout >= 2 {
r.currentTerm += 1
electionTimeout = 0
r.voteCount = 1
r.logger.Printf("[INFO] term is %d", r.currentTerm)
for _, member := range r.config.members {
go r.SendRequestVote(member)
}
}
}
}
// 该节点以LEADER状态运行,直到状态发生变化
func (r *RaftNode) runLeader() {
r.logger.Printf("[INFO] %s is now leader", r.config.addr)
go randomTimeout(r.toCh)
for r.state == LEADER {
// 发送心跳(存放日志信息)
for _, member := range r.config.members {
go r.SendHeartbeat(member)
}
select {
case rpc := <-r.rpcCh:
r.handleRPC(rpc)
case _ = <-r.toCh:
for _, member := range r.config.members {
go r.SendHeartbeat(member)
}
}
}
}
// 用于处理不同类型的RPC请求与响应
func (r *RaftNode) handleRPC(rpc *RaftRPC) {
switch rpc.St.(type) {
case AppendEntries:
r.HandleAppendEntries(rpc.St.(AppendEntries))
case AppendEntriesResponse:
r.HandleAppendEntriesResponse(rpc.St.(AppendEntriesResponse))
case RequestVote:
r.HandleRequestVote(rpc.St.(RequestVote))
case RequestVoteResponse:
r.HandleRequestVoteResponse(rpc.St.(RequestVoteResponse), &r.voteCount)
case ClientRequest:
r.HandleClientRequest(rpc.St.(ClientRequest))
default:
r.logger.Printf("[ERROR] 未知 RPC: %+v\n", rpc)
}
}
func (r *RaftNode) RunRaft() error {
// 监听端口
go r.RunTCPServer()
for {
if r.state == FOLLOWER {
r.runFollower()
} else if r.state == CANDIDATE {
r.runCandidate()
} else if r.state == LEADER {
r.runLeader()
} else {
return errors.New("state error")
}
}
}