domain: report min start timestamp of TiDB server

domain/domain.go

@@ -420,8 +420,12 @@ func (do *Domain) topNSlowQueryLoop() {
 func (do *Domain) infoSyncerKeeper() {
 	defer do.wg.Done()
 	defer recoverInDomain("infoSyncerKeeper", false)
+	ticker := time.NewTicker(time.Second * time.Duration(InfoSessionTTL) / 2)
+	defer ticker.Stop()
 	for {
 		select {
+		case <-ticker.C:
+			do.info.ReportMinStartTS()
 		case <-do.info.Done():
 			logutil.BgLogger().Info("server info syncer need to restart")
 			if err := do.info.Restart(context.Background()); err != nil {
@@ -547,6 +551,7 @@ func (do *Domain) Close() {
 	}
 	if do.info != nil {
 		do.info.RemoveServerInfo()
+		do.info.RemoveMinStartTS()
 	}
 	close(do.exit)
 	if do.etcdClient != nil {

domain/info.go

@@ -17,6 +17,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"math"
+	"strconv"
 	"time"
 
 	"github.com/coreos/etcd/clientv3"
@@ -26,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl/util"
 	"github.com/pingcap/tidb/owner"
+	util2 "github.com/pingcap/tidb/util"
 	"github.com/pingcap/tidb/util/hack"
 	"github.com/pingcap/tidb/util/logutil"
 	"github.com/pingcap/tidb/util/printer"
@@ -35,6 +38,8 @@ import (
 const (
 	// ServerInformationPath store server information such as IP, port and so on.
 	ServerInformationPath = "/tidb/server/info"
+	// ServerMinStartTSPath store the server min start timestamp.
+	ServerMinStartTSPath = "/tidb/server/minstartts"
 	// keyOpDefaultRetryCnt is the default retry count for etcd store.
 	keyOpDefaultRetryCnt = 2
 	// keyOpDefaultTimeout is the default time out for etcd store.
@@ -49,6 +54,9 @@ type InfoSyncer struct {
 	etcdCli        *clientv3.Client
 	info           *ServerInfo
 	serverInfoPath string
+	minStartTS     uint64
+	minStartTSPath string
+	manager        util2.SessionManager
 	session        *concurrency.Session
 }
 
@@ -75,6 +83,7 @@ func NewInfoSyncer(id string, etcdCli *clientv3.Client) *InfoSyncer {
 		etcdCli:        etcdCli,
 		info:           getServerInfo(id),
 		serverInfoPath: fmt.Sprintf("%s/%s", ServerInformationPath, id),
+		minStartTSPath: fmt.Sprintf("%s/%s", ServerMinStartTSPath, id),
 	}
 }
 
@@ -83,6 +92,11 @@ func (is *InfoSyncer) Init(ctx context.Context) error {
 	return is.newSessionAndStoreServerInfo(ctx, owner.NewSessionDefaultRetryCnt)
 }
 
+// SetSessionManager set the session manager for InfoSyncer.
+func (is *InfoSyncer) SetSessionManager(manager util2.SessionManager) {
+	is.manager = manager
+}
+
 // GetServerInfo gets self server static information.
 func (is *InfoSyncer) GetServerInfo() *ServerInfo {
 	return is.info
@@ -144,6 +158,47 @@ func (is *InfoSyncer) RemoveServerInfo() {
 	}
 }
 
+// storeMinStartTS stores self server min start timestamp to etcd.
+func (is *InfoSyncer) storeMinStartTS(ctx context.Context) error {
+	if is.etcdCli == nil {
+		return nil
+	}
+	return util.PutKVToEtcd(ctx, is.etcdCli, keyOpDefaultRetryCnt, is.minStartTSPath,
+		strconv.FormatUint(is.minStartTS, 10),
+		clientv3.WithLease(is.session.Lease()))
+}
+
+// RemoveMinStartTS removes self server min start timestamp from etcd.
+func (is *InfoSyncer) RemoveMinStartTS() {
+	if is.etcdCli == nil {
+		return
+	}
+	err := util.DeleteKeyFromEtcd(is.minStartTSPath, is.etcdCli, keyOpDefaultRetryCnt, keyOpDefaultTimeout)
+	if err != nil {
+		logutil.BgLogger().Error("remove minStartTS failed", zap.Error(err))
+	}
+}
+
+// ReportMinStartTS reports self server min start timestamp to ETCD.
+func (is *InfoSyncer) ReportMinStartTS() {
+	if is.manager == nil {
+		// Server may not start in time.
+		return
+	}
+	pl := is.manager.ShowProcessList()
+	var minStartTS uint64 = math.MaxUint64
+	for _, info := range pl {
+		if info.CurTxnStartTS < minStartTS {
+			minStartTS = info.CurTxnStartTS
+		}
+	}
+	is.minStartTS = minStartTS
+	err := is.storeMinStartTS(context.Background())
+	if err != nil {
+		logutil.BgLogger().Error("update minStartTS failed", zap.Error(err))
+	}
+}
+
 // Done returns a channel that closes when the info syncer is no longer being refreshed.
 func (is InfoSyncer) Done() <-chan struct{} {
 	if is.etcdCli == nil {

tidb-server/main.go

@@ -554,6 +554,7 @@ func createServer() {
 	// Both domain and storage have started, so we have to clean them before exiting.
 	terror.MustNil(err, closeDomainAndStorage)
 	go dom.ExpensiveQueryHandle().SetSessionManager(svr).Run()
+	dom.InfoSyncer().SetSessionManager(svr)
 }
 
 func serverShutdown(isgraceful bool) {