func (r *RegionInfo) GetFollowers() map[uint64]*metapb.Peer {
	peers := r.GetVoters()
	followers := make(map[uint64]*metapb.Peer, len(peers))
	for _, peer := range peers {
		if r.leader == nil || r.leader.GetId() != peer.GetId() {
			followers[peer.GetStoreId()] = peer
		}
	}
	return followers
}
GetFollowers returns a map indicate the follow peers distributed.
package core
import (
	"bytes"
	"encoding/hex"
	"fmt"
	"reflect"
	"sort"
	"strings"
	"unsafe"
	"github.com/gogo/protobuf/proto"
	"github.com/pingcap/errors"
	"github.com/pingcap/kvproto/pkg/metapb"
	"github.com/pingcap/kvproto/pkg/pdpb"
	"github.com/pingcap/kvproto/pkg/replication_modepb"
	"github.com/pingcap/log"
	"github.com/tikv/pd/pkg/logutil"
	"go.uber.org/zap"
)
func errRegionIsStale(region *metapb.Region, origin *metapb.Region) error {
	return errors.Errorf("region is stale: region %v origin %v", region, origin)
}
type RegionInfo struct {
	term              uint64
	meta              *metapb.Region
	learners          []*metapb.Peer
	voters            []*metapb.Peer
	leader            *metapb.Peer
	downPeers         []*pdpb.PeerStats
	pendingPeers      []*metapb.Peer
	writtenBytes      uint64
	writtenKeys       uint64
	readBytes         uint64
	readKeys          uint64
	approximateSize   int64
	approximateKeys   int64
	interval          *pdpb.TimeInterval
	replicationStatus *replication_modepb.RegionReplicationStatus
	QueryStats        *pdpb.QueryStats
	flowRoundDivisor  uint64
}
func NewRegionInfo(region *metapb.Region, leader *metapb.Peer, opts ...RegionCreateOption) *RegionInfo {
	regionInfo := &RegionInfo{
		meta:   region,
		leader: leader,
	}
	for _, opt := range opts {
		opt(regionInfo)
	}
	classifyVoterAndLearner(regionInfo)
	return regionInfo
}
func classifyVoterAndLearner(region *RegionInfo) {
	learners := make([]*metapb.Peer, 0, 1)
	voters := make([]*metapb.Peer, 0, len(region.meta.Peers))
	for _, p := range region.meta.Peers {
		if IsLearner(p) {
			learners = append(learners, p)
		} else {
			voters = append(voters, p)
		}
	}
	sort.Sort(peerSlice(learners))
	sort.Sort(peerSlice(voters))
	region.learners = learners
	region.voters = voters
}
const (
	EmptyRegionApproximateSize = 1
	ImpossibleFlowSize = 1 << 50
	statsReportMinInterval = 3       
	statsReportMaxInterval = 5 * 60  
)
func RegionFromHeartbeat(heartbeat *pdpb.RegionHeartbeatRequest, opts ...RegionCreateOption) *RegionInfo {
	regionSize := heartbeat.GetApproximateSize() / (1 << 20)
	if regionSize < EmptyRegionApproximateSize {
		regionSize = EmptyRegionApproximateSize
	}
	region := &RegionInfo{
		term:              heartbeat.GetTerm(),
		meta:              heartbeat.GetRegion(),
		leader:            heartbeat.GetLeader(),
		downPeers:         heartbeat.GetDownPeers(),
		pendingPeers:      heartbeat.GetPendingPeers(),
		writtenBytes:      heartbeat.GetBytesWritten(),
		writtenKeys:       heartbeat.GetKeysWritten(),
		readBytes:         heartbeat.GetBytesRead(),
		readKeys:          heartbeat.GetKeysRead(),
		approximateSize:   int64(regionSize),
		approximateKeys:   int64(heartbeat.GetApproximateKeys()),
		interval:          heartbeat.GetInterval(),
		replicationStatus: heartbeat.GetReplicationStatus(),
		QueryStats:        heartbeat.GetQueryStats(),
	}
	for _, opt := range opts {
		opt(region)
	}
	if region.writtenKeys >= ImpossibleFlowSize || region.writtenBytes >= ImpossibleFlowSize {
		region.writtenKeys = 0
		region.writtenBytes = 0
	}
	if region.readKeys >= ImpossibleFlowSize || region.readBytes >= ImpossibleFlowSize {
		region.readKeys = 0
		region.readBytes = 0
	}
	sort.Sort(peerStatsSlice(region.downPeers))
	sort.Sort(peerSlice(region.pendingPeers))
	classifyVoterAndLearner(region)
	return region
}
func (r *RegionInfo) Clone(opts ...RegionCreateOption) *RegionInfo {
	downPeers := make([]*pdpb.PeerStats, 0, len(r.downPeers))
	for _, peer := range r.downPeers {
		downPeers = append(downPeers, proto.Clone(peer).(*pdpb.PeerStats))
	}
	pendingPeers := make([]*metapb.Peer, 0, len(r.pendingPeers))
	for _, peer := range r.pendingPeers {
		pendingPeers = append(pendingPeers, proto.Clone(peer).(*metapb.Peer))
	}
	region := &RegionInfo{
		term:              r.term,
		meta:              proto.Clone(r.meta).(*metapb.Region),
		leader:            proto.Clone(r.leader).(*metapb.Peer),
		downPeers:         downPeers,
		pendingPeers:      pendingPeers,
		writtenBytes:      r.writtenBytes,
		writtenKeys:       r.writtenKeys,
		readBytes:         r.readBytes,
		readKeys:          r.readKeys,
		approximateSize:   r.approximateSize,
		approximateKeys:   r.approximateKeys,
		interval:          proto.Clone(r.interval).(*pdpb.TimeInterval),
		replicationStatus: r.replicationStatus,
	}
	for _, opt := range opts {
		opt(region)
	}
	classifyVoterAndLearner(region)
	return region
}
func (r *RegionInfo) GetTerm() uint64 {
	return r.term
}
func (r *RegionInfo) GetLearners() []*metapb.Peer {
	return r.learners
}
func (r *RegionInfo) GetVoters() []*metapb.Peer {
	return r.voters
}
func (r *RegionInfo) GetPeer(peerID uint64) *metapb.Peer {
	for _, peer := range r.meta.GetPeers() {
		if peer.GetId() == peerID {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetDownPeer(peerID uint64) *metapb.Peer {
	for _, down := range r.downPeers {
		if down.GetPeer().GetId() == peerID {
			return down.GetPeer()
		}
	}
	return nil
}
func (r *RegionInfo) GetDownVoter(peerID uint64) *metapb.Peer {
	for _, down := range r.downPeers {
		if down.GetPeer().GetId() == peerID && !IsLearner(down.GetPeer()) {
			return down.GetPeer()
		}
	}
	return nil
}
func (r *RegionInfo) GetDownLearner(peerID uint64) *metapb.Peer {
	for _, down := range r.downPeers {
		if down.GetPeer().GetId() == peerID && IsLearner(down.GetPeer()) {
			return down.GetPeer()
		}
	}
	return nil
}
func (r *RegionInfo) GetPendingPeer(peerID uint64) *metapb.Peer {
	for _, peer := range r.pendingPeers {
		if peer.GetId() == peerID {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetPendingVoter(peerID uint64) *metapb.Peer {
	for _, peer := range r.pendingPeers {
		if peer.GetId() == peerID && !IsLearner(peer) {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetPendingLearner(peerID uint64) *metapb.Peer {
	for _, peer := range r.pendingPeers {
		if peer.GetId() == peerID && IsLearner(peer) {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetStorePeer(storeID uint64) *metapb.Peer {
	for _, peer := range r.meta.GetPeers() {
		if peer.GetStoreId() == storeID {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetStoreVoter(storeID uint64) *metapb.Peer {
	for _, peer := range r.voters {
		if peer.GetStoreId() == storeID {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetStoreLearner(storeID uint64) *metapb.Peer {
	for _, peer := range r.learners {
		if peer.GetStoreId() == storeID {
			return peer
		}
	}
	return nil
}
func (r *RegionInfo) GetStoreIds() map[uint64]struct{} {
	peers := r.meta.GetPeers()
	stores := make(map[uint64]struct{}, len(peers))
	for _, peer := range peers {
		stores[peer.GetStoreId()] = struct{}{}
	}
	return stores
}