/
idle.go
217 lines (185 loc) · 5.98 KB
/
idle.go
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/*
* Xenon
*
* Copyright 2018 The Xenon Authors.
* Code is licensed under the GPLv3.
*
*/
package raft
import (
"model"
)
// IDLE is a special STATE with other FOLLOWER/CANDICATE/LEADER states.
// It is usually used as READ-ONLY but does not have RAFT features, such as
// LEADER election
// FOLLOWER promotion
//
// Because of we bring IDLE state in RaftRPCResponse as vote-request response,
// the IDLE vote will be filtered out by other CANDIDATEs.
// IDLE is not one member of a RAFT cluster and without the rights to vote.
// Idle tuple.
type Idle struct {
*Raft
// idle process heartbeat request handler
processHeartbeatRequestHandler func(*model.RaftRPCRequest) *model.RaftRPCResponse
// idle process voterequest request handler
processRequestVoteRequestHandler func(*model.RaftRPCRequest) *model.RaftRPCResponse
// idle process ping request handler
processPingRequestHandler func(*model.RaftRPCRequest) *model.RaftRPCResponse
}
// NewIdle creates new Idle.
func NewIdle(r *Raft) *Idle {
I := &Idle{Raft: r}
I.initHandlers()
return I
}
// Loop used to start the loop of the state machine.
//--------------------------------------
// State Machine
//--------------------------------------
// in IDLE state, we never do leader election
//
func (r *Idle) Loop() {
// update begin
r.updateStateBegin()
r.stateInit()
for r.getState() == IDLE {
select {
case <-r.fired:
r.WARNING("state.machine.loop.got.fired")
case e := <-r.c:
switch e.Type {
// 1) Heartbeat
case MsgRaftHeartbeat:
req := e.request.(*model.RaftRPCRequest)
rsp := r.processHeartbeatRequestHandler(req)
e.response <- rsp
// 2) RequestVote
case MsgRaftRequestVote:
req := e.request.(*model.RaftRPCRequest)
rsp := r.processRequestVoteRequest(req)
e.response <- rsp
// 3) Ping
case MsgRaftPing:
req := e.request.(*model.RaftRPCRequest)
rsp := r.processPingRequestHandler(req)
e.response <- rsp
default:
r.ERROR("get.unknown.request[%v]", e.Type)
}
}
}
}
// processHeartbeatRequest
// EFFECT
// handles the heartbeat request from the leader
// In IDLE state, we only handle the master changed
//
func (r *Idle) processHeartbeatRequest(req *model.RaftRPCRequest) *model.RaftRPCResponse {
rsp := model.NewRaftRPCResponse(model.OK)
rsp.Raft.From = r.getID()
rsp.Raft.ViewID = r.getViewID()
rsp.Raft.EpochID = r.getEpochID()
rsp.Raft.State = r.state.String()
rsp.Relay_Master_Log_File = r.mysql.RelayMasterLogFile()
if !r.checkRequest(req) {
rsp.RetCode = model.ErrorInvalidRequest
return rsp
}
viewdiff := (int)(r.getViewID() - req.GetViewID())
epochdiff := (int)(r.getEpochID() - req.GetEpochID())
switch {
case viewdiff <= 0:
// MySQL1: disable master semi-sync because I am a slave
if err := r.mysql.DisableSemiSyncMaster(); err != nil {
r.ERROR("mysql.DisableSemiSyncMaster.error[%v]", err)
}
// MySQL2: set mysql readonly(mysql maybe down and up then the LEADER changes)
if err := r.mysql.SetReadOnly(); err != nil {
r.ERROR("mysql.SetReadOnly.error[%v]", err)
}
// MySQL3: start slave
if err := r.mysql.StartSlave(); err != nil {
r.ERROR("mysql.StartSlave.error[%v]", err)
}
// MySQL4: change master
if r.getLeader() != req.GetFrom() {
r.WARNING("get.heartbeat.from[N:%v, V:%v, E:%v].change.mysql.master[%+v]", req.GetFrom(), req.GetViewID(), req.GetEpochID(), req.GetGTID())
if err := r.mysql.ChangeMasterTo(&req.Repl); err != nil {
r.ERROR("change.master.to[FROM:%v, GTID:%v].error[%v]", req.GetFrom(), req.GetRepl(), err)
rsp.RetCode = model.ErrorChangeMaster
return rsp
}
r.leader = req.GetFrom()
}
// view change
if viewdiff < 0 {
r.WARNING("get.heartbeat.from[N:%v, V:%v, E:%v].update.view", req.GetFrom(), req.GetViewID(), req.GetEpochID())
r.updateView(req.GetViewID(), req.GetFrom())
}
// epoch change
if epochdiff != 0 {
r.WARNING("get.heartbeat.from[N:%v, V:%v, E:%v].update.epoch", req.GetFrom(), req.GetViewID(), req.GetEpochID())
r.updateEpoch(req.GetEpochID(), req.GetPeers(), req.GetIdlePeers())
}
}
return rsp
}
// processRequestVoteRequest
// EFFECT
// handles the requestvote request from other CANDIDATEs
// IDLE is special, it returns OK expect Request Denied
//
// RETURN
// 1. OK: give a vote, but the Candidate will abandon the Idle's vote.
func (r *Idle) processRequestVoteRequest(req *model.RaftRPCRequest) *model.RaftRPCResponse {
rsp := model.NewRaftRPCResponse(model.OK)
rsp.Raft.From = r.getID()
rsp.Raft.ViewID = r.getViewID()
rsp.Raft.EpochID = r.getEpochID()
rsp.Raft.State = r.state.String()
if !r.checkRequest(req) {
rsp.RetCode = model.ErrorInvalidRequest
return rsp
}
return rsp
}
func (r *Idle) stateInit() {
// 1. stop vip
if err := r.leaderStopShellCommand(); err != nil {
// TODO(array): what todo?
r.ERROR("stopshell.error[%v]", err)
}
// MySQL1: set readonly
if err := r.mysql.SetReadOnly(); err != nil {
r.ERROR("mysql.SetReadOnly.error[%v]", err)
}
// MySQL2. set mysql slave system variables
if err := r.mysql.SetSlaveGlobalSysVar(); err != nil {
r.ERROR("mysql.SetSlaveGlobalSysVar.error[%v]", err)
}
}
func (r *Idle) processPingRequest(req *model.RaftRPCRequest) *model.RaftRPCResponse {
rsp := model.NewRaftRPCResponse(model.OK)
rsp.Raft.From = r.getID()
rsp.Raft.ViewID = r.getViewID()
rsp.Raft.EpochID = r.getEpochID()
rsp.Raft.State = r.state.String()
return rsp
}
// handlers
func (r *Idle) initHandlers() {
r.setProcessHeartbeatRequestHandler(r.processHeartbeatRequest)
r.setProcessRequestVoteRequestHandler(r.processRequestVoteRequest)
r.setProcessPingRequestHandler(r.processPingRequest)
}
// for tests
func (r *Idle) setProcessHeartbeatRequestHandler(f func(*model.RaftRPCRequest) *model.RaftRPCResponse) {
r.processHeartbeatRequestHandler = f
}
func (r *Idle) setProcessRequestVoteRequestHandler(f func(*model.RaftRPCRequest) *model.RaftRPCResponse) {
r.processRequestVoteRequestHandler = f
}
func (r *Idle) setProcessPingRequestHandler(f func(*model.RaftRPCRequest) *model.RaftRPCResponse) {
r.processPingRequestHandler = f
}