Пример #1
0
// UpdateSrvShard creates the SrvShard object based on the global ShardInfo,
// and writes it to the given cell.
func UpdateSrvShard(ctx context.Context, ts topo.Server, cell string, si *topo.ShardInfo) error {
	srvShard := &topo.SrvShard{
		Name:       si.ShardName(),
		KeyRange:   si.KeyRange,
		MasterCell: si.MasterAlias.Cell,
	}
	return ts.UpdateSrvShard(ctx, cell, si.Keyspace(), si.ShardName(), srvShard)
}
Пример #2
0
func CheckServingGraph(t *testing.T, ts topo.Server) {
	cell := getLocalCell(t, ts)

	// test individual cell/keyspace/shard/type entries
	if _, err := ts.GetSrvTabletTypesPerShard(cell, "test_keyspace", "-10"); err != topo.ErrNoNode {
		t.Errorf("GetSrvTabletTypesPerShard(invalid): %v", err)
	}
	if _, err := ts.GetEndPoints(cell, "test_keyspace", "-10", topo.TYPE_MASTER); err != topo.ErrNoNode {
		t.Errorf("GetEndPoints(invalid): %v", err)
	}

	endPoints := topo.EndPoints{
		Entries: []topo.EndPoint{
			topo.EndPoint{
				Uid:          1,
				Host:         "host1",
				NamedPortMap: map[string]int{"_vt": 1234, "_mysql": 1235, "_vts": 1236},
			},
		},
	}

	if err := ts.UpdateEndPoints(cell, "test_keyspace", "-10", topo.TYPE_MASTER, &endPoints); err != nil {
		t.Errorf("UpdateEndPoints(master): %v", err)
	}
	if types, err := ts.GetSrvTabletTypesPerShard(cell, "test_keyspace", "-10"); err != nil || len(types) != 1 || types[0] != topo.TYPE_MASTER {
		t.Errorf("GetSrvTabletTypesPerShard(1): %v %v", err, types)
	}

	addrs, err := ts.GetEndPoints(cell, "test_keyspace", "-10", topo.TYPE_MASTER)
	if err != nil {
		t.Errorf("GetEndPoints: %v", err)
	}
	if len(addrs.Entries) != 1 || addrs.Entries[0].Uid != 1 {
		t.Errorf("GetEndPoints(1): %v", addrs)
	}
	if pm := addrs.Entries[0].NamedPortMap; pm["_vt"] != 1234 || pm["_mysql"] != 1235 || pm["_vts"] != 1236 {
		t.Errorf("GetSrcTabletType(1).NamedPortmap: want %v, got %v", endPoints.Entries[0].NamedPortMap, pm)
	}

	if err := ts.UpdateTabletEndpoint(cell, "test_keyspace", "-10", topo.TYPE_REPLICA, &topo.EndPoint{Uid: 2, Host: "host2"}); err != nil {
		t.Errorf("UpdateTabletEndpoint(invalid): %v", err)
	}
	if err := ts.UpdateTabletEndpoint(cell, "test_keyspace", "-10", topo.TYPE_MASTER, &topo.EndPoint{Uid: 1, Host: "host2"}); err != nil {
		t.Errorf("UpdateTabletEndpoint(master): %v", err)
	}
	if addrs, err := ts.GetEndPoints(cell, "test_keyspace", "-10", topo.TYPE_MASTER); err != nil || len(addrs.Entries) != 1 || addrs.Entries[0].Uid != 1 {
		t.Errorf("GetEndPoints(2): %v %v", err, addrs)
	}
	if err := ts.UpdateTabletEndpoint(cell, "test_keyspace", "-10", topo.TYPE_MASTER, &topo.EndPoint{Uid: 3, Host: "host3"}); err != nil {
		t.Errorf("UpdateTabletEndpoint(master): %v", err)
	}
	if addrs, err := ts.GetEndPoints(cell, "test_keyspace", "-10", topo.TYPE_MASTER); err != nil || len(addrs.Entries) != 2 {
		t.Errorf("GetEndPoints(2): %v %v", err, addrs)
	}

	if err := ts.DeleteSrvTabletType(cell, "test_keyspace", "-10", topo.TYPE_REPLICA); err != topo.ErrNoNode {
		t.Errorf("DeleteSrvTabletType(unknown): %v", err)
	}
	if err := ts.DeleteSrvTabletType(cell, "test_keyspace", "-10", topo.TYPE_MASTER); err != nil {
		t.Errorf("DeleteSrvTabletType(master): %v", err)
	}

	// test cell/keyspace/shard entries (SrvShard)
	srvShard := topo.SrvShard{
		ServedTypes: []topo.TabletType{topo.TYPE_MASTER},
		TabletTypes: []topo.TabletType{topo.TYPE_REPLICA, topo.TYPE_RDONLY},
	}
	if err := ts.UpdateSrvShard(cell, "test_keyspace", "-10", &srvShard); err != nil {
		t.Errorf("UpdateSrvShard(1): %v", err)
	}
	if _, err := ts.GetSrvShard(cell, "test_keyspace", "666"); err != topo.ErrNoNode {
		t.Errorf("GetSrvShard(invalid): %v", err)
	}
	if s, err := ts.GetSrvShard(cell, "test_keyspace", "-10"); err != nil ||
		len(s.ServedTypes) != 1 ||
		s.ServedTypes[0] != topo.TYPE_MASTER ||
		len(s.TabletTypes) != 2 ||
		s.TabletTypes[0] != topo.TYPE_REPLICA ||
		s.TabletTypes[1] != topo.TYPE_RDONLY {
		t.Errorf("GetSrvShard(valid): %v", err)
	}

	// test cell/keyspace entries (SrvKeyspace)
	srvKeyspace := topo.SrvKeyspace{
		Partitions: map[topo.TabletType]*topo.KeyspacePartition{
			topo.TYPE_MASTER: &topo.KeyspacePartition{
				Shards: []topo.SrvShard{
					topo.SrvShard{
						ServedTypes: []topo.TabletType{topo.TYPE_MASTER},
					},
				},
			},
		},
		TabletTypes: []topo.TabletType{topo.TYPE_MASTER},
	}
	if err := ts.UpdateSrvKeyspace(cell, "test_keyspace", &srvKeyspace); err != nil {
		t.Errorf("UpdateSrvKeyspace(1): %v", err)
	}
	if _, err := ts.GetSrvKeyspace(cell, "test_keyspace666"); err != topo.ErrNoNode {
		t.Errorf("GetSrvKeyspace(invalid): %v", err)
	}
	if s, err := ts.GetSrvKeyspace(cell, "test_keyspace"); err != nil ||
		len(s.TabletTypes) != 1 ||
		s.TabletTypes[0] != topo.TYPE_MASTER ||
		len(s.Partitions) != 1 ||
		len(s.Partitions[topo.TYPE_MASTER].Shards) != 1 ||
		len(s.Partitions[topo.TYPE_MASTER].Shards[0].ServedTypes) != 1 ||
		s.Partitions[topo.TYPE_MASTER].Shards[0].ServedTypes[0] != topo.TYPE_MASTER {
		t.Errorf("GetSrvKeyspace(valid): %v", err)
	}
	if k, err := ts.GetSrvKeyspaceNames(cell); err != nil || len(k) != 1 || k[0] != "test_keyspace" {
		t.Errorf("GetSrvKeyspaceNames(): %v", err)
	}
}
Пример #3
0
// rebuildCellSrvShard computes and writes the serving graph data to a
// single cell
func rebuildCellSrvShard(log logutil.Logger, ts topo.Server, shardInfo *topo.ShardInfo, cell string, tablets map[topo.TabletAlias]*topo.TabletInfo) error {
	log.Infof("rebuildCellSrvShard %v/%v in cell %v", shardInfo.Keyspace(), shardInfo.ShardName(), cell)

	// Get all existing db types so they can be removed if nothing
	// had been edited.
	existingTabletTypes, err := ts.GetSrvTabletTypesPerShard(cell, shardInfo.Keyspace(), shardInfo.ShardName())
	if err != nil {
		if err != topo.ErrNoNode {
			return err
		}
	}

	// Update db type addresses in the serving graph
	//
	// locationAddrsMap is a map:
	//   key: tabletType
	//   value: EndPoints (list of server records)
	locationAddrsMap := make(map[topo.TabletType]*topo.EndPoints)
	for _, tablet := range tablets {
		if !tablet.IsInReplicationGraph() {
			// only valid case is a scrapped master in the
			// catastrophic reparent case
			if tablet.Parent.Uid != topo.NO_TABLET {
				log.Warningf("Tablet %v should not be in the replication graph, please investigate (it is being ignored in the rebuild)", tablet.Alias)
			}
			continue
		}

		// Check IsInServingGraph, we don't want to add tablets that
		// are not serving
		if !tablet.IsInServingGraph() {
			continue
		}

		// Check the Keyspace and Shard for the tablet are right
		if tablet.Keyspace != shardInfo.Keyspace() || tablet.Shard != shardInfo.ShardName() {
			return fmt.Errorf("CRITICAL: tablet %v is in replication graph for shard %v/%v but belongs to shard %v:%v", tablet.Alias, shardInfo.Keyspace(), shardInfo.ShardName(), tablet.Keyspace, tablet.Shard)
		}

		// Add the tablet to the list
		addrs, ok := locationAddrsMap[tablet.Type]
		if !ok {
			addrs = topo.NewEndPoints()
			locationAddrsMap[tablet.Type] = addrs
		}
		entry, err := tablet.Tablet.EndPoint()
		if err != nil {
			log.Warningf("EndPointForTablet failed for tablet %v: %v", tablet.Alias, err)
			continue
		}
		addrs.Entries = append(addrs.Entries, *entry)
	}

	// we're gonna parallelize a lot here:
	// - writing all the tabletTypes records
	// - removing the unused records
	// - writing SrvShard
	rec := concurrency.AllErrorRecorder{}
	wg := sync.WaitGroup{}

	// write all the EndPoints nodes everywhere we want them
	for tabletType, addrs := range locationAddrsMap {
		wg.Add(1)
		go func(tabletType topo.TabletType, addrs *topo.EndPoints) {
			log.Infof("saving serving graph for cell %v shard %v/%v tabletType %v", cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType)
			if err := ts.UpdateEndPoints(cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType, addrs); err != nil {
				rec.RecordError(fmt.Errorf("writing endpoints for cell %v shard %v/%v tabletType %v failed: %v", cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType, err))
			}
			wg.Done()
		}(tabletType, addrs)
	}

	// Delete any pre-existing paths that were not updated by this process.
	// That's the existingTabletTypes - locationAddrsMap
	for _, tabletType := range existingTabletTypes {
		if _, ok := locationAddrsMap[tabletType]; !ok {
			wg.Add(1)
			go func(tabletType topo.TabletType) {
				log.Infof("removing stale db type from serving graph: %v", tabletType)
				if err := ts.DeleteEndPoints(cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType); err != nil {
					log.Warningf("unable to remove stale db type %v from serving graph: %v", tabletType, err)
				}
				wg.Done()
			}(tabletType)
		}
	}

	// Update srvShard object
	wg.Add(1)
	go func() {
		log.Infof("updating shard serving graph in cell %v for %v/%v", cell, shardInfo.Keyspace(), shardInfo.ShardName())
		srvShard := &topo.SrvShard{
			Name:        shardInfo.ShardName(),
			KeyRange:    shardInfo.KeyRange,
			ServedTypes: shardInfo.ServedTypes,
			MasterCell:  shardInfo.MasterAlias.Cell,
			TabletTypes: make([]topo.TabletType, 0, len(locationAddrsMap)),
		}
		for tabletType := range locationAddrsMap {
			srvShard.TabletTypes = append(srvShard.TabletTypes, tabletType)
		}

		if err := ts.UpdateSrvShard(cell, shardInfo.Keyspace(), shardInfo.ShardName(), srvShard); err != nil {
			rec.RecordError(fmt.Errorf("writing serving data in cell %v for %v/%v failed: %v", cell, shardInfo.Keyspace(), shardInfo.ShardName(), err))
		}
		wg.Done()
	}()

	wg.Wait()
	return rec.Error()
}
Пример #4
0
// CheckServingGraph makes sure the serving graph functions work properly.
func CheckServingGraph(ctx context.Context, t *testing.T, ts topo.Server) {
	cell := getLocalCell(ctx, t, ts)

	// test individual cell/keyspace/shard/type entries
	if _, err := ts.GetSrvTabletTypesPerShard(ctx, cell, "test_keyspace", "-10"); err != topo.ErrNoNode {
		t.Errorf("GetSrvTabletTypesPerShard(invalid): %v", err)
	}
	if _, _, err := ts.GetEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER); err != topo.ErrNoNode {
		t.Errorf("GetEndPoints(invalid): %v", err)
	}

	endPoints := &pb.EndPoints{
		Entries: []*pb.EndPoint{
			&pb.EndPoint{
				Uid:  1,
				Host: "host1",
				PortMap: map[string]int32{
					"vt":    1234,
					"mysql": 1235,
					"grpc":  1236,
				},
			},
		},
	}

	if err := ts.CreateEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints); err != nil {
		t.Fatalf("CreateEndPoints(master): %v", err)
	}
	// Try to create again.
	if err := ts.CreateEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints); err != topo.ErrNodeExists {
		t.Fatalf("CreateEndPoints(master): err = %v, want topo.ErrNodeExists", err)
	}

	// Get version.
	_, version, err := ts.GetEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER)
	if err != nil {
		t.Fatalf("GetEndPoints(master): %v", err)
	}
	// Make a change.
	tmp := endPoints.Entries[0].Uid
	endPoints.Entries[0].Uid = tmp + 1
	if err := topo.UpdateEndPoints(ctx, ts, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints, -1); err != nil {
		t.Fatalf("UpdateEndPoints(master): %v", err)
	}
	endPoints.Entries[0].Uid = tmp
	// Try to delete with the wrong version.
	if err := ts.DeleteEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER, version); err != topo.ErrBadVersion {
		t.Fatalf("DeleteEndPoints: err = %v, want topo.ErrBadVersion", err)
	}
	// Delete with the correct version.
	_, version, err = ts.GetEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER)
	if err != nil {
		t.Fatalf("GetEndPoints(master): %v", err)
	}
	if err := ts.DeleteEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER, version); err != nil {
		t.Fatalf("DeleteEndPoints: %v", err)
	}
	// Recreate it with an unconditional update.
	if err := topo.UpdateEndPoints(ctx, ts, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints, -1); err != nil {
		t.Fatalf("UpdateEndPoints(master): %v", err)
	}

	if types, err := ts.GetSrvTabletTypesPerShard(ctx, cell, "test_keyspace", "-10"); err != nil || len(types) != 1 || types[0] != topo.TYPE_MASTER {
		t.Errorf("GetSrvTabletTypesPerShard(1): %v %v", err, types)
	}

	// Delete it unconditionally.
	if err := ts.DeleteEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER, -1); err != nil {
		t.Fatalf("DeleteEndPoints: %v", err)
	}

	// Delete the SrvShard.
	if err := ts.DeleteSrvShard(ctx, cell, "test_keyspace", "-10"); err != nil {
		t.Fatalf("DeleteSrvShard: %v", err)
	}
	if _, err := ts.GetSrvShard(ctx, cell, "test_keyspace", "-10"); err != topo.ErrNoNode {
		t.Errorf("GetSrvShard(deleted) got %v, want ErrNoNode", err)
	}

	// Re-add endpoints.
	if err := topo.UpdateEndPoints(ctx, ts, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints, -1); err != nil {
		t.Fatalf("UpdateEndPoints(master): %v", err)
	}

	addrs, version, err := ts.GetEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER)
	if err != nil {
		t.Errorf("GetEndPoints: %v", err)
	}
	if len(addrs.Entries) != 1 || addrs.Entries[0].Uid != 1 {
		t.Errorf("GetEndPoints(1): %v", addrs)
	}
	if pm := addrs.Entries[0].PortMap; pm["vt"] != 1234 || pm["mysql"] != 1235 || pm["grpc"] != 1236 {
		t.Errorf("GetSrcTabletType(1).PortMap: want %v, got %v", endPoints.Entries[0].PortMap, pm)
	}

	// Update with the wrong version.
	if err := topo.UpdateEndPoints(ctx, ts, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints, version+1); err != topo.ErrBadVersion {
		t.Fatalf("UpdateEndPoints(master): err = %v, want topo.ErrBadVersion", err)
	}
	// Update with the right version.
	if err := topo.UpdateEndPoints(ctx, ts, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints, version); err != nil {
		t.Fatalf("UpdateEndPoints(master): %v", err)
	}
	// Update existing EndPoints unconditionally.
	if err := topo.UpdateEndPoints(ctx, ts, cell, "test_keyspace", "-10", topo.TYPE_MASTER, endPoints, -1); err != nil {
		t.Fatalf("UpdateEndPoints(master): %v", err)
	}

	if err := ts.DeleteEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_REPLICA, -1); err != topo.ErrNoNode {
		t.Errorf("DeleteEndPoints(unknown): %v", err)
	}
	if err := ts.DeleteEndPoints(ctx, cell, "test_keyspace", "-10", topo.TYPE_MASTER, -1); err != nil {
		t.Errorf("DeleteEndPoints(master): %v", err)
	}

	// test cell/keyspace/shard entries (SrvShard)
	srvShard := &pb.SrvShard{
		Name:       "-10",
		KeyRange:   newKeyRange3("-10"),
		MasterCell: "test",
	}
	if err := ts.UpdateSrvShard(ctx, cell, "test_keyspace", "-10", srvShard); err != nil {
		t.Fatalf("UpdateSrvShard(1): %v", err)
	}
	if _, err := ts.GetSrvShard(ctx, cell, "test_keyspace", "666"); err != topo.ErrNoNode {
		t.Errorf("GetSrvShard(invalid): %v", err)
	}
	if s, err := ts.GetSrvShard(ctx, cell, "test_keyspace", "-10"); err != nil ||
		s.Name != "-10" ||
		!key.KeyRangeEqual(s.KeyRange, newKeyRange3("-10")) ||
		s.MasterCell != "test" {
		t.Errorf("GetSrvShard(valid): %v", err)
	}

	// test cell/keyspace entries (SrvKeyspace)
	srvKeyspace := topo.SrvKeyspace{
		Partitions: map[topo.TabletType]*topo.KeyspacePartition{
			topo.TYPE_MASTER: &topo.KeyspacePartition{
				ShardReferences: []topo.ShardReference{
					topo.ShardReference{
						Name:     "-80",
						KeyRange: newKeyRange("-80"),
					},
				},
			},
		},
		ShardingColumnName: "video_id",
		ShardingColumnType: key.KIT_UINT64,
		ServedFrom: map[topo.TabletType]string{
			topo.TYPE_REPLICA: "other_keyspace",
		},
	}
	if err := ts.UpdateSrvKeyspace(ctx, cell, "test_keyspace", &srvKeyspace); err != nil {
		t.Errorf("UpdateSrvKeyspace(1): %v", err)
	}
	if _, err := ts.GetSrvKeyspace(ctx, cell, "test_keyspace666"); err != topo.ErrNoNode {
		t.Errorf("GetSrvKeyspace(invalid): %v", err)
	}
	if k, err := ts.GetSrvKeyspace(ctx, cell, "test_keyspace"); err != nil ||
		len(k.Partitions) != 1 ||
		len(k.Partitions[topo.TYPE_MASTER].ShardReferences) != 1 ||
		k.Partitions[topo.TYPE_MASTER].ShardReferences[0].Name != "-80" ||
		k.Partitions[topo.TYPE_MASTER].ShardReferences[0].KeyRange != newKeyRange("-80") ||
		k.ShardingColumnName != "video_id" ||
		k.ShardingColumnType != key.KIT_UINT64 ||
		k.ServedFrom[topo.TYPE_REPLICA] != "other_keyspace" {
		t.Errorf("GetSrvKeyspace(valid): %v %v", err, k)
	}
	if k, err := ts.GetSrvKeyspaceNames(ctx, cell); err != nil || len(k) != 1 || k[0] != "test_keyspace" {
		t.Errorf("GetSrvKeyspaceNames(): %v", err)
	}

	// check that updating a SrvKeyspace out of the blue works
	if err := ts.UpdateSrvKeyspace(ctx, cell, "unknown_keyspace_so_far", &srvKeyspace); err != nil {
		t.Fatalf("UpdateSrvKeyspace(2): %v", err)
	}
	if k, err := ts.GetSrvKeyspace(ctx, cell, "unknown_keyspace_so_far"); err != nil ||
		len(k.Partitions) != 1 ||
		len(k.Partitions[topo.TYPE_MASTER].ShardReferences) != 1 ||
		k.Partitions[topo.TYPE_MASTER].ShardReferences[0].Name != "-80" ||
		k.Partitions[topo.TYPE_MASTER].ShardReferences[0].KeyRange != newKeyRange("-80") ||
		k.ShardingColumnName != "video_id" ||
		k.ShardingColumnType != key.KIT_UINT64 ||
		k.ServedFrom[topo.TYPE_REPLICA] != "other_keyspace" {
		t.Errorf("GetSrvKeyspace(out of the blue): %v %v", err, *k)
	}

	// Delete the SrvKeyspace.
	if err := ts.DeleteSrvKeyspace(ctx, cell, "unknown_keyspace_so_far"); err != nil {
		t.Fatalf("DeleteSrvShard: %v", err)
	}
	if _, err := ts.GetSrvKeyspace(ctx, cell, "unknown_keyspace_so_far"); err != topo.ErrNoNode {
		t.Errorf("GetSrvKeyspace(deleted) got %v, want ErrNoNode", err)
	}
}
Пример #5
0
// Write serving graph data to the cells
func rebuildShardSrvGraph(ts topo.Server, shardInfo *topo.ShardInfo, tablets []*topo.TabletInfo, cells []string) error {
	log.Infof("rebuildShardSrvGraph %v/%v", shardInfo.Keyspace(), shardInfo.ShardName())

	// Get all existing db types so they can be removed if nothing
	// had been editted.  This applies to all cells, which can't
	// be determined until you walk through all the tablets.
	//
	// existingDbTypeLocations is a map:
	//   key: {cell,keyspace,shard,tabletType}
	//   value: true
	existingDbTypeLocations := make(map[cellKeyspaceShardType]bool)

	// Update db type addresses in the serving graph
	//
	// locationAddrsMap is a map:
	//   key: {cell,keyspace,shard,tabletType}
	//   value: EndPoints (list of server records)
	locationAddrsMap := make(map[cellKeyspaceShardType]*topo.EndPoints)

	// we keep track of the existingDbTypeLocations we've already looked at
	knownShardLocations := make(map[cellKeyspaceShard]bool)

	for _, tablet := range tablets {
		// only look at tablets in the cells we want to rebuild
		if !topo.InCellList(tablet.Tablet.Alias.Cell, cells) {
			continue
		}

		// this is {cell,keyspace,shard}
		// we'll get the children to find the existing types
		shardLocation := cellKeyspaceShard{tablet.Tablet.Alias.Cell, tablet.Tablet.Keyspace, tablet.Shard}
		// only need to do this once per cell
		if !knownShardLocations[shardLocation] {
			log.Infof("Getting tablet types on cell %v for %v/%v", tablet.Tablet.Alias.Cell, tablet.Tablet.Keyspace, tablet.Shard)
			tabletTypes, err := ts.GetSrvTabletTypesPerShard(tablet.Tablet.Alias.Cell, tablet.Tablet.Keyspace, tablet.Shard)
			if err != nil {
				if err != topo.ErrNoNode {
					return err
				}
			} else {
				for _, tabletType := range tabletTypes {
					existingDbTypeLocations[cellKeyspaceShardType{tablet.Tablet.Alias.Cell, tablet.Tablet.Keyspace, tablet.Shard, tabletType}] = true
				}
			}
			knownShardLocations[shardLocation] = true
		}

		// Check IsInServingGraph after we have populated
		// existingDbTypeLocations so we properly prune data
		// if the definition of serving type changes.
		if !tablet.IsInServingGraph() {
			continue
		}

		location := cellKeyspaceShardType{tablet.Tablet.Alias.Cell, tablet.Keyspace, tablet.Shard, tablet.Type}
		addrs, ok := locationAddrsMap[location]
		if !ok {
			addrs = topo.NewEndPoints()
			locationAddrsMap[location] = addrs
		}

		entry, err := tablet.Tablet.EndPoint()
		if err != nil {
			log.Warningf("EndPointForTablet failed for tablet %v: %v", tablet.Alias, err)
			continue
		}
		addrs.Entries = append(addrs.Entries, *entry)
	}

	// we're gonna parallelize a lot here
	rec := concurrency.AllErrorRecorder{}
	wg := sync.WaitGroup{}

	// write all the {cell,keyspace,shard,type}
	// nodes everywhere we want them
	for location, addrs := range locationAddrsMap {
		wg.Add(1)
		go func(location cellKeyspaceShardType, addrs *topo.EndPoints) {
			log.Infof("saving serving graph for cell %v shard %v/%v tabletType %v", location.cell, location.keyspace, location.shard, location.tabletType)
			if err := ts.UpdateEndPoints(location.cell, location.keyspace, location.shard, location.tabletType, addrs); err != nil {
				rec.RecordError(fmt.Errorf("writing endpoints for cell %v shard %v/%v tabletType %v failed: %v", location.cell, location.keyspace, location.shard, location.tabletType, err))
			}
			wg.Done()
		}(location, addrs)
	}

	// Delete any pre-existing paths that were not updated by this process.
	// That's the existingDbTypeLocations - locationAddrsMap
	for dbTypeLocation := range existingDbTypeLocations {
		if _, ok := locationAddrsMap[dbTypeLocation]; !ok {
			cell := dbTypeLocation.cell
			if !topo.InCellList(cell, cells) {
				continue
			}

			wg.Add(1)
			go func(dbTypeLocation cellKeyspaceShardType) {
				log.Infof("removing stale db type from serving graph: %v", dbTypeLocation)
				if err := ts.DeleteEndPoints(dbTypeLocation.cell, dbTypeLocation.keyspace, dbTypeLocation.shard, dbTypeLocation.tabletType); err != nil {
					log.Warningf("unable to remove stale db type %v from serving graph: %v", dbTypeLocation, err)
				}
				wg.Done()
			}(dbTypeLocation)
		}
	}

	// wait until we're done with the background stuff to do the rest
	// FIXME(alainjobart) this wouldn't be necessary if UpdateSrvShard
	// below was creating the zookeeper nodes recursively.
	wg.Wait()
	if err := rec.Error(); err != nil {
		return err
	}

	// Update per-shard information per cell-specific serving path.
	//
	// srvShardByPath is a map:
	//   key: {cell,keyspace,shard}
	//   value: SrvShard
	// this will create all the SrvShard objects
	srvShardByPath := make(map[cellKeyspaceShard]*topo.SrvShard)
	for location := range locationAddrsMap {
		// location will be {cell,keyspace,shard,type}
		srvShardPath := cellKeyspaceShard{location.cell, location.keyspace, location.shard}
		srvShard, ok := srvShardByPath[srvShardPath]
		if !ok {
			srvShard = &topo.SrvShard{
				KeyRange:    shardInfo.KeyRange,
				ServedTypes: shardInfo.ServedTypes,
				TabletTypes: make([]topo.TabletType, 0, 2),
			}
			srvShardByPath[srvShardPath] = srvShard
		}
		foundType := false
		for _, t := range srvShard.TabletTypes {
			if t == location.tabletType {
				foundType = true
			}
		}
		if !foundType {
			srvShard.TabletTypes = append(srvShard.TabletTypes, location.tabletType)
		}
	}

	// Save the shard entries
	for cks, srvShard := range srvShardByPath {
		wg.Add(1)
		go func(cks cellKeyspaceShard, srvShard *topo.SrvShard) {
			log.Infof("updating shard serving graph in cell %v for %v/%v", cks.cell, cks.keyspace, cks.shard)
			if err := ts.UpdateSrvShard(cks.cell, cks.keyspace, cks.shard, srvShard); err != nil {
				rec.RecordError(fmt.Errorf("writing serving data in cell %v for %v/%v failed: %v", cks.cell, cks.keyspace, cks.shard, err))
			}
			wg.Done()
		}(cks, srvShard)
	}
	wg.Wait()
	return rec.Error()
}