syncer: add region syncer client status

pkg/syncer/client.go

@@ -19,6 +19,8 @@ import (
 	"time"
 
 	"github.com/docker/go-units"
+	"github.com/pingcap/errors"
+	"github.com/pingcap/failpoint"
 	"github.com/pingcap/kvproto/pkg/metapb"
 	"github.com/pingcap/kvproto/pkg/pdpb"
 	"github.com/pingcap/log"
@@ -77,6 +79,11 @@ func (s *RegionSyncer) syncRegion(ctx context.Context, conn *grpc.ClientConn) (C
 
 var regionGuide = core.GenerateRegionGuideFunc(false)
 
+// IsRunning returns whether the region syncer client is running.
+func (s *RegionSyncer) IsRunning() bool {
+	return s.streamingRunning.Load()
+}
+
 // StartSyncWithLeader starts to sync with leader.
 func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 	s.wg.Add(1)
@@ -89,6 +96,7 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 	go func() {
 		defer logutil.LogPanic()
 		defer s.wg.Done()
+		defer s.streamingRunning.Store(false)
 		// used to load region from kv storage to cache storage.
 		bc := s.server.GetBasicCluster()
 		regionStorage := s.server.GetStorage()
@@ -132,6 +140,9 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 			}
 
 			stream, err := s.syncRegion(ctx, conn)
+			failpoint.Inject("disableClientStreaming", func() {
+				err = errors.Errorf("no stream")
+			})
 			if err != nil {
 				if ev, ok := status.FromError(err); ok {
 					if ev.Code() == codes.Canceled {
@@ -142,11 +153,11 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 				time.Sleep(time.Second)
 				continue
 			}
-
 			log.Info("server starts to synchronize with leader", zap.String("server", s.server.Name()), zap.String("leader", s.server.GetLeader().GetName()), zap.Uint64("request-index", s.history.GetNextIndex()))
 			for {
 				resp, err := stream.Recv()
 				if err != nil {
+					s.streamingRunning.Store(false)
 					log.Error("region sync with leader meet error", errs.ZapError(errs.ErrGRPCRecv, err))
 					if err = stream.CloseSend(); err != nil {
 						log.Error("failed to terminate client stream", errs.ZapError(errs.ErrGRPCCloseSend, err))
@@ -212,6 +223,8 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 						_ = regionStorage.DeleteRegion(old.GetMeta())
 					}
 				}
+				// mark the client as running status when it finished the first history region sync.
+				s.streamingRunning.Store(true)
 			}
 		}
 	}()

pkg/syncer/server.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"io"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/docker/go-units"
@@ -83,6 +84,8 @@ type RegionSyncer struct {
 	history   *historyBuffer
 	limit     *ratelimit.RateLimiter
 	tlsConfig *grpcutil.TLSConfig
+	// status when as client
+	streamingRunning atomic.Bool
 }
 
 // NewRegionSyncer returns a region syncer.
@@ -228,7 +231,16 @@ func (s *RegionSyncer) syncHistoryRegion(ctx context.Context, request *pdpb.Sync
 		if s.history.GetNextIndex() == startIndex {
 			log.Info("requested server has already in sync with server",
 				zap.String("requested-server", name), zap.String("server", s.server.Name()), zap.Uint64("last-index", startIndex))
-			return nil
+			// still send a response to follower to show the history region sync.
+			resp := &pdpb.SyncRegionResponse{
+				Header:        &pdpb.ResponseHeader{ClusterId: s.server.ClusterID()},
+				Regions:       nil,
+				StartIndex:    startIndex,
+				RegionStats:   nil,
+				RegionLeaders: nil,
+				Buckets:       nil,
+			}
+			return stream.Send(resp)
 		}
 		// do full synchronization
 		if startIndex == 0 {

server/server.go

@@ -1363,6 +1363,12 @@ func (s *Server) GetRaftCluster() *cluster.RaftCluster {
 	return s.cluster
 }
 
+// DirectlyGetRaftCluster returns raft cluster directly.
+// Only used for test.
+func (s *Server) DirectlyGetRaftCluster() *cluster.RaftCluster {
+	return s.cluster
+}
+
 // GetCluster gets cluster.
 func (s *Server) GetCluster() *metapb.Cluster {
 	return &metapb.Cluster{

tests/server/region_syncer/region_syncer_test.go

@@ -47,21 +47,34 @@ func (i *idAllocator) alloc() uint64 {
 func TestRegionSyncer(t *testing.T) {
 	re := require.New(t)
 	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
 	re.NoError(failpoint.Enable("github.com/tikv/pd/pkg/storage/regionStorageFastFlush", `return(true)`))
 	re.NoError(failpoint.Enable("github.com/tikv/pd/pkg/syncer/noFastExitSync", `return(true)`))
+	re.NoError(failpoint.Enable("github.com/tikv/pd/pkg/syncer/disableClientStreaming", `return(true)`))
 
 	cluster, err := tests.NewTestCluster(ctx, 3, func(conf *config.Config, serverName string) { conf.PDServerCfg.UseRegionStorage = true })
-	defer cluster.Destroy()
+	defer func() {
+		cluster.Destroy()
+		cancel()
+	}()
 	re.NoError(err)
 
 	re.NoError(cluster.RunInitialServers())
 	cluster.WaitLeader()
 	leaderServer := cluster.GetLeaderServer()
+
 	re.NoError(leaderServer.BootstrapCluster())
 	rc := leaderServer.GetServer().GetRaftCluster()
 	re.NotNil(rc)
+	followerServer := cluster.GetServer(cluster.GetFollower())
+
+	testutil.Eventually(re, func() bool {
+		return !followerServer.GetServer().DirectlyGetRaftCluster().GetRegionSyncer().IsRunning()
+	})
+	re.NoError(failpoint.Disable("github.com/tikv/pd/pkg/syncer/disableClientStreaming"))
 	re.True(cluster.WaitRegionSyncerClientsReady(2))
+	testutil.Eventually(re, func() bool {
+		return followerServer.GetServer().DirectlyGetRaftCluster().GetRegionSyncer().IsRunning()
+	})
 
 	regionLen := 110
 	regions := initRegions(regionLen)
@@ -119,7 +132,6 @@ func TestRegionSyncer(t *testing.T) {
 	time.Sleep(4 * time.Second)
 
 	// test All regions have been synchronized to the cache of followerServer
-	followerServer := cluster.GetServer(cluster.GetFollower())
 	re.NotNil(followerServer)
 	cacheRegions := leaderServer.GetServer().GetBasicCluster().GetRegions()
 	re.Len(cacheRegions, regionLen)
@@ -141,6 +153,9 @@ func TestRegionSyncer(t *testing.T) {
 	re.NoError(err)
 	cluster.WaitLeader()
 	leaderServer = cluster.GetLeaderServer()
+	testutil.Eventually(re, func() bool {
+		return !leaderServer.GetServer().GetRaftCluster().GetRegionSyncer().IsRunning()
+	})
 	re.NotNil(leaderServer)
 	loadRegions := leaderServer.GetServer().GetRaftCluster().GetRegions()
 	re.Len(loadRegions, regionLen)