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raft_fsm_follower.go
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raft_fsm_follower.go
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package raft
import (
"math"
"github.com/tiglabs/raft/logger"
"github.com/tiglabs/raft/proto"
)
func (r *raftFsm) becomeFollower(term, lead uint64) {
r.step = stepFollower
r.reset(term, 0, false)
r.tick = r.tickElection
r.leader = lead
r.state = stateFollower
if logger.IsEnableDebug() {
logger.Debug("[raft][%v] became follower at term[%d] leader[%d].", r.id, r.term, r.leader)
}
}
func stepFollower(r *raftFsm, m *proto.Message) {
switch m.Type {
case proto.LocalMsgProp:
if r.leader == NoLeader {
if logger.IsEnableWarn() {
logger.Warn("raft[%v] no leader at term %d; dropping proposal.", r.id, r.term)
}
return
}
m.To = r.leader
r.send(m)
return
case proto.ReqMsgAppend:
r.electionElapsed = 0
r.leader = m.From
r.handleAppendEntries(m)
proto.ReturnMessage(m)
return
case proto.ReqMsgHeartBeat:
r.electionElapsed = 0
r.leader = m.From
return
case proto.ReqMsgElectAck:
r.electionElapsed = 0
r.leader = m.From
nmsg := proto.GetMessage()
nmsg.Type = proto.RespMsgElectAck
nmsg.To = m.From
r.send(nmsg)
proto.ReturnMessage(m)
return
case proto.ReqMsgVote:
fpri, lpri := uint16(math.MaxUint16), uint16(0)
if pr, ok := r.replicas[m.From]; ok {
fpri = pr.peer.Priority
}
if pr, ok := r.replicas[r.config.NodeID]; ok {
lpri = pr.peer.Priority
}
if (!r.config.LeaseCheck || r.leader == NoLeader) && (r.vote == NoLeader || r.vote == m.From) && r.raftLog.isUpToDate(m.Index, m.LogTerm, fpri, lpri) {
r.electionElapsed = 0
if logger.IsEnableDebug() {
logger.Debug("raft[%v] [logterm: %d, index: %d, vote: %v] voted for %v [logterm: %d, index: %d] at term %d.", r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.vote, m.From, m.LogTerm, m.Index, r.term)
}
r.vote = m.From
nmsg := proto.GetMessage()
nmsg.Type = proto.RespMsgVote
nmsg.To = m.From
r.send(nmsg)
} else {
if logger.IsEnableDebug() {
logger.Debug("raf[%v] [logterm: %d, index: %d, vote: %v] rejected vote from %v [logterm: %d, index: %d] at term %d.", r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.vote, m.From, m.LogTerm, m.Index, r.term)
}
nmsg := proto.GetMessage()
nmsg.Type = proto.RespMsgVote
nmsg.To = m.From
nmsg.Reject = true
r.send(nmsg)
}
proto.ReturnMessage(m)
return
case proto.LeaseMsgTimeout:
if r.leader == m.From {
r.electionElapsed = 0
nmsg := proto.GetMessage()
nmsg.Type = proto.LocalMsgHup
nmsg.From = r.config.NodeID
r.Step(nmsg)
}
proto.ReturnMessage(m)
return
}
}
func (r *raftFsm) tickElection() {
if !r.promotable() {
r.electionElapsed = 0
return
}
r.electionElapsed++
timeout := false
// check follower lease (2 * electiontimeout)
if r.config.LeaseCheck && r.leader != NoLeader && r.state == stateFollower {
timeout = (r.electionElapsed >= (r.config.ElectionTick << 1))
} else {
timeout = r.pastElectionTimeout()
}
if timeout {
r.electionElapsed = 0
m := proto.GetMessage()
m.Type = proto.LocalMsgHup
m.From = r.config.NodeID
r.Step(m)
}
}
func (r *raftFsm) handleAppendEntries(m *proto.Message) {
if m.Index < r.raftLog.committed {
nmsg := proto.GetMessage()
nmsg.Type = proto.RespMsgAppend
nmsg.To = m.From
nmsg.Index = r.raftLog.committed
nmsg.Commit = r.raftLog.committed
r.send(nmsg)
return
}
if mlastIndex, ok := r.raftLog.maybeAppend(m.Index, m.LogTerm, m.Commit, m.Entries...); ok {
nmsg := proto.GetMessage()
nmsg.Type = proto.RespMsgAppend
nmsg.To = m.From
nmsg.Index = mlastIndex
nmsg.Commit = r.raftLog.committed
r.send(nmsg)
} else {
if logger.IsEnableDebug() {
logger.Debug("raft[%v logterm: %d, index: %d] rejected msgApp [logterm: %d, index: %d] from %v",
r.id, r.raftLog.zeroTermOnErrCompacted(r.raftLog.term(m.Index)), m.Index, m.LogTerm, m.Index, m.From)
}
nmsg := proto.GetMessage()
nmsg.Type = proto.RespMsgAppend
nmsg.To = m.From
nmsg.Index = m.Index
nmsg.Commit = r.raftLog.committed
nmsg.Reject = true
nmsg.RejectIndex = r.raftLog.lastIndex()
r.send(nmsg)
}
}
func (r *raftFsm) promotable() bool {
_, ok := r.replicas[r.config.NodeID]
return ok
}