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operator: remove empty JointConsensus steps and fix single voter demote bug (#4534) #4552

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merged 3 commits into from
Feb 21, 2022
Merged

operator: remove empty JointConsensus steps and fix single voter demote bug (#4534) #4552

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14d6a04
This is an automated cherry-pick of #4534
matchge-ca Jan 6, 2022
eb19c1d
sync code
HunDunDM Jan 6, 2022
d2aa67b
Merge branch 'release-5.3' into cherry-pick-4534-to-release-5.3
ti-chi-bot Feb 21, 2022
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64 changes: 33 additions & 31 deletions server/schedule/operator/builder.go
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,6 @@ type Builder struct {
skipOriginJointStateCheck bool

// build flags
allowDemote bool
useJointConsensus bool
lightWeight bool
forceTargetLeader bool
Expand Down Expand Up @@ -147,7 +146,6 @@ func NewBuilder(desc string, cluster opt.Cluster, region *core.RegionInfo, opts
b.unhealthyPeers = unhealthyPeers
b.originLeaderStoreID = originLeaderStoreID
b.targetPeers = originPeers.Copy()
b.allowDemote = supportJointConsensus
b.useJointConsensus = supportJointConsensus && cluster.GetOpts().IsUseJointConsensus()
b.err = err
return b
Expand Down Expand Up @@ -354,7 +352,7 @@ func (b *Builder) prepareBuild() (string, error) {
}

// Diff `originPeers` and `targetPeers` to initialize `toAdd`, `toRemove`, `toPromote`, `toDemote`.
// Note: Use `toDemote` only when `allowDemote` is true. Otherwise use `toAdd`, `toRemove` instead.
// Note: Use `toDemote` only when `useJointConsensus` is true. Otherwise use `toAdd`, `toRemove` instead.
for _, o := range b.originPeers {
n := b.targetPeers[o.GetStoreId()]
if n == nil {
Expand All @@ -372,27 +370,25 @@ func (b *Builder) prepareBuild() (string, error) {
}
}

if core.IsLearner(o) {
if !core.IsLearner(n) {
// learner -> voter
b.toPromote.Set(n)
}
} else {
if core.IsLearner(n) {
// voter -> learner
if b.allowDemote {
b.toDemote.Set(n)
} else {
b.toRemove.Set(o)
// Need to add `b.toAdd.Set(n)` in the later targetPeers loop
}
isOriginPeerLearner := core.IsLearner(o)
isTargetPeerLearner := core.IsLearner(n)
if isOriginPeerLearner && !isTargetPeerLearner {
// learner -> voter
b.toPromote.Set(n)
} else if !isOriginPeerLearner && isTargetPeerLearner {
// voter -> learner
if b.useJointConsensus {
b.toDemote.Set(n)
} else {
b.toRemove.Set(o)
// the targetPeers loop below will add `b.toAdd.Set(n)`
}
}
}
for _, n := range b.targetPeers {
// old peer not exists, or target is learner while old one is voter.
o := b.originPeers[n.GetStoreId()]
if o == nil || (!b.allowDemote && !core.IsLearner(o) && core.IsLearner(n)) {
if o == nil || (!b.useJointConsensus && !core.IsLearner(o) && core.IsLearner(n)) {
if n.GetId() == 0 {
// Allocate peer ID if need.
id, err := b.cluster.AllocID()
Expand Down Expand Up @@ -424,8 +420,8 @@ func (b *Builder) prepareBuild() (string, error) {
}
}

if len(b.toAdd)+len(b.toRemove)+len(b.toPromote)+len(b.toDemote) <= 1 {
// If only one peer changed, joint consensus is not used.
if len(b.toAdd)+len(b.toRemove)+len(b.toPromote) <= 1 && len(b.toDemote) == 0 {
// if only one peer changed and the change type is not demote, joint consensus is not used
b.useJointConsensus = false
}

Expand Down Expand Up @@ -607,9 +603,6 @@ func (b *Builder) buildStepsWithoutJointConsensus(kind OpKind) (OpKind, error) {
b.execTransferLeader(plan.leaderBeforeRemove)
kind |= OpLeader
}
if plan.demote != nil {
b.execDemoteFollower(plan.demote)
}
if plan.remove != nil {
b.execRemovePeer(plan.remove)
kind |= OpRegion
Expand Down Expand Up @@ -643,12 +636,6 @@ func (b *Builder) execPromoteLearner(peer *metapb.Peer) {
delete(b.toPromote, peer.GetStoreId())
}

func (b *Builder) execDemoteFollower(peer *metapb.Peer) {
b.steps = append(b.steps, DemoteFollower{ToStore: peer.GetStoreId(), PeerID: peer.GetId()})
b.currentPeers.Set(peer)
delete(b.toDemote, peer.GetStoreId())
}

func (b *Builder) execAddPeer(peer *metapb.Peer) {
if b.lightWeight {
b.steps = append(b.steps, AddLearner{ToStore: peer.GetStoreId(), PeerID: peer.GetId(), IsLightWeight: b.lightWeight})
Expand Down Expand Up @@ -676,6 +663,17 @@ func (b *Builder) execRemovePeer(peer *metapb.Peer) {
}

func (b *Builder) execChangePeerV2(needEnter bool, needTransferLeader bool) {
if len(b.toPromote)+len(b.toDemote) == 0 {
// No need to add empty enter / leave joint consensus step if no peer in `toPromote` and `toDemote`

// Transfer Leader
if needTransferLeader && b.originLeaderStoreID != b.targetLeaderStoreID {
b.execTransferLeader(b.targetLeaderStoreID)
}

return
}

// Enter
step := ChangePeerV2Enter{
PromoteLearners: make([]PromoteLearner, 0, len(b.toPromote)),
Expand All @@ -699,12 +697,16 @@ func (b *Builder) execChangePeerV2(needEnter bool, needTransferLeader bool) {
if needEnter {
b.steps = append(b.steps, step)
}

// Transfer Leader
if needTransferLeader && b.originLeaderStoreID != b.targetLeaderStoreID {
b.execTransferLeader(b.targetLeaderStoreID)
}
// Leave
b.steps = append(b.steps, ChangePeerV2Leave(step))

// TiKV will handle leave step if only single peer change in promote and demote when enter step is bypassed
if !(needEnter && len(step.PromoteLearners)+len(step.DemoteVoters) == 1) {
b.steps = append(b.steps, ChangePeerV2Leave(step))
}
}

// check if the peer is allowed to become the leader.
Expand Down
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