vtorc: store cells in backend and periodically refresh

go/vt/vtorc/db/generate_base.go

@@ -29,9 +29,10 @@ var TableNames = []string{
 	"global_recovery_disable",
 	"topology_recovery_steps",
 	"database_instance_stale_binlog_coordinates",
-	"vitess_tablet",
+	"vitess_cell",
 	"vitess_keyspace",
 	"vitess_shard",
+	"vitess_tablet",
 }
 
 // vtorcBackend is a list of SQL statements required to build the vtorc backend
@@ -307,6 +308,14 @@ CREATE TABLE vitess_shard (
 	PRIMARY KEY (keyspace, shard)
 )`,
 	`
+DROP TABLE IF EXISTS vitess_cell
+`,
+	`
+CREATE TABLE vitess_cell (
+	cell varchar(128) NOT NULL,
+	PRIMARY KEY (cell)
+)`,
+	`
 CREATE INDEX source_host_port_idx_database_instance_database_instance on database_instance (source_host, source_port)
 	`,
 	`

go/vt/vtorc/inst/cell_dao.go

@@ -0,0 +1,45 @@
+/*
+Copyright 2025 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package inst
+
+import (
+	"vitess.io/vitess/go/vt/external/golib/sqlutils"
+	"vitess.io/vitess/go/vt/vtorc/db"
+)
+
+// ReadCells reads all the vitess cell names.
+func ReadCells() ([]string, error) {
+	cells := make([]string, 0)
+	query := `SELECT cell FROM vitess_cell`
+	err := db.QueryVTOrc(query, nil, func(row sqlutils.RowMap) error {
+		cells = append(cells, row.GetString("cell"))
+		return nil
+	})
+	return cells, err
+}
+
+// SaveCell saves the keyspace record against the keyspace name.
+func SaveCell(cell string) error {
+	_, err := db.ExecVTOrc(`REPLACE INTO vitess_cell (cell) VALUES(?)`, cell)
+	return err
+}
+
+// DeleteCell deletes a cell.
+func DeleteCell(cell string) (err error) {
+	_, err = db.ExecVTOrc(`DELETE FROM vitess_cell WHERE cell = ?`, cell)
+	return err
+}

go/vt/vtorc/inst/cell_dao_test.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2025 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package inst
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"vitess.io/vitess/go/vt/vtorc/db"
+)
+
+func TestSaveReadAndDeleteCells(t *testing.T) {
+	db.ClearVTOrcDatabase()
+	defer db.ClearVTOrcDatabase()
+
+	cells := []string{"zone1", "zone2", "zone3"}
+	for _, cell := range cells {
+		require.NoError(t, SaveCell(cell))
+	}
+	cellsRead, err := ReadCells()
+	require.NoError(t, err)
+	require.Equal(t, cells, cellsRead)
+
+	require.NoError(t, DeleteCell("zone3"))
+	cellsRead, err = ReadCells()
+	require.NoError(t, err)
+	require.Equal(t, []string{"zone1", "zone2"}, cellsRead)
+}

go/vt/vtorc/logic/cell_discovery.go

@@ -0,0 +1,77 @@
+/*
+Copyright 2025 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package logic
+
+import (
+	"context"
+	"sync"
+
+	"vitess.io/vitess/go/vt/log"
+	"vitess.io/vitess/go/vt/topo"
+	"vitess.io/vitess/go/vt/vtorc/inst"
+)
+
+var saveAllCellsMu sync.Mutex
+
+// RefreshCells refreshes the list of cells.
+func RefreshCells(ctx context.Context) error {
+	cellsCtx, cellsCancel := context.WithTimeout(ctx, topo.RemoteOperationTimeout)
+	defer cellsCancel()
+	cells, err := ts.GetKnownCells(cellsCtx)
+	if err != nil {
+		return err
+	}
+	return saveAllCells(cells)
+}
+
+// saveAllCells saves a slice representing all cells
+// and removes stale cells that were not updated.
+func saveAllCells(allCells []string) (err error) {
+	saveAllCellsMu.Lock()
+	defer saveAllCellsMu.Unlock()
+
+	// save cells.
+	updated := make(map[string]bool, len(allCells))
+	for _, cell := range allCells {
+		if err = inst.SaveCell(cell); err != nil {
+			log.Errorf("Failed to save cell %s: %+v", cell, err)
+			return err
+		}
+		updated[cell] = true
+	}
+
+	// read all saved cells. the values should not be changing
+	// because we are holding a lock and updates originate
+	// from this func only.
+	cells, err := inst.ReadCells()
+	if err != nil {
+		log.Errorf("Failed to read all cells: %+v", err)
+		return err
+	}
+
+	// delete cells that are stale.
+	for _, cell := range cells {
+		if updated[cell] {
+			continue
+		}
+		log.Infof("Forgetting stale cell %s", cell)
+		if err = inst.DeleteCell(cell); err != nil {
+			log.Errorf("Failed to delete cell %s: %+v", cell, err)
+		}
+	}
+	return nil
+}

go/vt/vtorc/logic/cell_discovery_test.go

@@ -0,0 +1,53 @@
+/*
+Copyright 2025 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package logic
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"vitess.io/vitess/go/vt/topo/memorytopo"
+	"vitess.io/vitess/go/vt/vtorc/db"
+	"vitess.io/vitess/go/vt/vtorc/inst"
+)
+
+func TestRefreshCells(t *testing.T) {
+	db.ClearVTOrcDatabase()
+	oldTs := ts
+	defer func() {
+		db.ClearVTOrcDatabase()
+		ts = oldTs
+	}()
+
+	cells := []string{"zone1", "zone2", "zone3"}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	ts = memorytopo.NewServer(ctx, cells...)
+
+	require.NoError(t, RefreshCells(ctx))
+	cellsRead, err := inst.ReadCells()
+	require.NoError(t, err)
+	require.Equal(t, cells, cellsRead)
+
+	require.NoError(t, ts.DeleteCellInfo(ctx, "zone3", true))
+	require.NoError(t, RefreshCells(ctx))
+	cellsRead, err = inst.ReadCells()
+	require.NoError(t, err)
+	require.Equal(t, []string{"zone1", "zone2"}, cellsRead)
+}

go/vt/vtorc/logic/tablet_discovery.go

@@ -181,13 +181,14 @@ func refreshAllTablets(ctx context.Context) error {
 
 // refreshTabletsUsing refreshes tablets using a provided loader.
 func refreshTabletsUsing(ctx context.Context, loader func(tabletAlias string), forceRefresh bool) error {
-	// Get all cells.
-	ctx, cancel := context.WithTimeout(ctx, topo.RemoteOperationTimeout)
-	defer cancel()
-	cells, err := ts.GetKnownCells(ctx)
+	cells, err := inst.ReadCells()
 	if err != nil {
 		return err
 	}
+	if len(cells) == 0 {
+		log.Error("Found no cells")
+		return nil
+	}
 
 	// Get all tablets from all cells.
 	getTabletsCtx, getTabletsCancel := context.WithTimeout(ctx, topo.RemoteOperationTimeout)
@@ -236,7 +237,12 @@ func refreshTabletInfoOfShard(ctx context.Context, keyspace, shard string) {
 }
 
 func refreshTabletsInKeyspaceShard(ctx context.Context, keyspace, shard string, loader func(tabletAlias string), forceRefresh bool, tabletsToIgnore []string) {
-	tablets, err := ts.GetTabletsByShard(ctx, keyspace, shard)
+	cells, err := inst.ReadCells()
+	if err != nil {
+		log.Errorf("Error fetching cells: %v", err)
+		return
+	}
+	tablets, err := ts.GetTabletsByShardCell(ctx, keyspace, shard, cells)
 	if err != nil {
 		log.Errorf("Error fetching tablets for keyspace/shard %v/%v: %v", keyspace, shard, err)
 		return

go/vt/vtorc/logic/vtorc.go

@@ -321,6 +321,11 @@ func refreshAllInformation(ctx context.Context) error {
 	// Create an errgroup
 	eg, ctx := errgroup.WithContext(ctx)
 
+	// Refresh all cells.
+	eg.Go(func() error {
+		return RefreshCells(ctx)
+	})
+
 	// Refresh all keyspace information.
 	eg.Go(func() error {
 		return RefreshAllKeyspacesAndShards(ctx)