Improve efficiency of vtorc topo calls

go/flags/endtoend/vtorc.txt

@@ -99,6 +99,7 @@ Flags:
       --topo_global_root string                                     the path of the global topology data in the global topology server
       --topo_global_server_address string                           the address of the global topology server
       --topo_implementation string                                  the topology implementation to use
+      --topo_read_concurrency int                                   Concurrency of topo reads. (default 32)
       --topo_zk_auth_file string                                    auth to use when connecting to the zk topo server, file contents should be <scheme>:<auth>, e.g., digest:user:pass
       --topo_zk_base_timeout duration                               zk base timeout (see zk.Connect) (default 30s)
       --topo_zk_max_concurrency int                                 maximum number of pending requests to send to a Zookeeper server. (default 64)

go/vt/topo/keyspace.go

@@ -57,6 +57,7 @@ func init() {
 	servenv.OnParseFor("vtcombo", registerFlags)
 	servenv.OnParseFor("vtctld", registerFlags)
 	servenv.OnParseFor("vtgate", registerFlags)
+	servenv.OnParseFor("vtorc", registerFlags)
 }
 
 // KeyspaceInfo is a meta struct that contains metadata to give the

go/vt/topo/shard.go

@@ -20,28 +20,27 @@ import (
 	"context"
 	"encoding/hex"
 	"errors"
-	"fmt"
 	"path"
 	"slices"
 	"sort"
 	"strings"
 	"sync"
 	"time"
 
-	"vitess.io/vitess/go/constants/sidecar"
-	"vitess.io/vitess/go/protoutil"
-	"vitess.io/vitess/go/vt/proto/vtrpc"
-	"vitess.io/vitess/go/vt/vterrors"
+	"golang.org/x/sync/errgroup"
 
+	"vitess.io/vitess/go/constants/sidecar"
 	"vitess.io/vitess/go/event"
+	"vitess.io/vitess/go/protoutil"
 	"vitess.io/vitess/go/trace"
 	"vitess.io/vitess/go/vt/concurrency"
 	"vitess.io/vitess/go/vt/key"
 	"vitess.io/vitess/go/vt/log"
+	topodatapb "vitess.io/vitess/go/vt/proto/topodata"
+	"vitess.io/vitess/go/vt/proto/vtrpc"
 	"vitess.io/vitess/go/vt/topo/events"
 	"vitess.io/vitess/go/vt/topo/topoproto"
-
-	topodatapb "vitess.io/vitess/go/vt/proto/topodata"
+	"vitess.io/vitess/go/vt/vterrors"
 )
 
 const (
@@ -553,7 +552,6 @@ func (ts *Server) FindAllTabletAliasesInShardByCell(ctx context.Context, keyspac
 	span.Annotate("shard", shard)
 	span.Annotate("num_cells", len(cells))
 	defer span.Finish()
-	ctx = trace.NewContext(ctx, span)
 	var err error
 
 	// The caller intents to all cells
@@ -597,7 +595,7 @@ func (ts *Server) FindAllTabletAliasesInShardByCell(ctx context.Context, keyspac
 			case IsErrType(err, NoNode):
 				// There is no shard replication for this shard in this cell. NOOP
 			default:
-				rec.RecordError(vterrors.Wrap(err, fmt.Sprintf("GetShardReplication(%v, %v, %v) failed.", cell, keyspace, shard)))
+				rec.RecordError(vterrors.Wrapf(err, "GetShardReplication(%v, %v, %v) failed.", cell, keyspace, shard))
 				return
 			}
 		}(cell)
@@ -616,6 +614,76 @@ func (ts *Server) FindAllTabletAliasesInShardByCell(ctx context.Context, keyspac
 	return result, err
 }
 
+// GetTabletsByShard returns the tablets in the given shard using all cells.
+// It can return ErrPartialResult if it couldn't read all the cells, or all
+// the individual tablets, in which case the result is valid, but partial.
+func (ts *Server) GetTabletsByShard(ctx context.Context, keyspace, shard string) ([]*TabletInfo, error) {
+	return ts.GetTabletsByShardCell(ctx, keyspace, shard, nil)
+}
+
+// GetTabletsByShardCell returns the tablets in the given shard. It can return
+// ErrPartialResult if it couldn't read all the cells, or all the individual
+// tablets, in which case the result is valid, but partial.
+func (ts *Server) GetTabletsByShardCell(ctx context.Context, keyspace, shard string, cells []string) ([]*TabletInfo, error) {
+	span, ctx := trace.NewSpan(ctx, "topo.GetTabletsByShardCell")
+	span.Annotate("keyspace", keyspace)
+	span.Annotate("shard", shard)
+	span.Annotate("num_cells", len(cells))
+	defer span.Finish()
+	var err error
+
+	if len(cells) == 0 {
+		cells, err = ts.GetCellInfoNames(ctx)
+		if err != nil {
+			return nil, err
+		}
+		if len(cells) == 0 { // Nothing to do
+			return nil, nil
+		}
+	}
+
+	// Divide the concurrency limit by the number of cells. If there are more
+	// cells than the limit, default to concurrency of 1.
+	cellConcurrency := 1
+	if len(cells) < DefaultConcurrency {
+		cellConcurrency = DefaultConcurrency / len(cells)
+	}
+
+	mu := sync.Mutex{}
+	eg, ctx := errgroup.WithContext(ctx)
+	eg.SetLimit(DefaultConcurrency)
+
+	tablets := make([]*TabletInfo, 0, len(cells))
+	var kss *KeyspaceShard
+	if keyspace != "" {
+		kss = &KeyspaceShard{
+			Keyspace: keyspace,
+			Shard:    shard,
+		}
+	}
+	options := &GetTabletsByCellOptions{
+		Concurrency:   cellConcurrency,
+		KeyspaceShard: kss,
+	}
+	for _, cell := range cells {
+		eg.Go(func() error {
+			t, err := ts.GetTabletsByCell(ctx, cell, options)
+			if err != nil {
+				return vterrors.Wrapf(err, "GetTabletsByCell for %v failed.", cell)
+			}
+			mu.Lock()
+			defer mu.Unlock()
+			tablets = append(tablets, t...)
+			return nil
+		})
+	}
+	if err := eg.Wait(); err != nil {
+		log.Warningf("GetTabletsByShardCell(%v,%v): got partial result: %v", keyspace, shard, err)
+		return tablets, NewError(PartialResult, shard)
+	}
+	return tablets, nil
+}
+
 // GetTabletMapForShard returns the tablets for a shard. It can return
 // ErrPartialResult if it couldn't read all the cells, or all
 // the individual tablets, in which case the map is valid, but partial.

go/vt/topo/tablet.go

@@ -236,6 +236,9 @@ func (ts *Server) GetTabletAliasesByCell(ctx context.Context, cell string) ([]*t
 type GetTabletsByCellOptions struct {
 	// Concurrency controls the maximum number of concurrent calls to GetTablet.
 	Concurrency int
+	// KeyspaceShard is the optional keyspace/shard that tablets must match.
+	// An empty shard value will match all shards in the keyspace.
+	KeyspaceShard *KeyspaceShard
 }
 
 // GetTabletsByCell returns all the tablets in the cell.
@@ -263,15 +266,27 @@ func (ts *Server) GetTabletsByCell(ctx context.Context, cellAlias string, opt *G
 		return nil, err
 	}
 
-	tablets := make([]*TabletInfo, len(listResults))
+	var capHint int
+	if opt != nil && opt.KeyspaceShard == nil {
+		capHint = len(listResults)
+	}
+
+	tablets := make([]*TabletInfo, 0, capHint)
 	for n := range listResults {
 		tablet := &topodatapb.Tablet{}
 		if err := tablet.UnmarshalVT(listResults[n].Value); err != nil {
 			return nil, err
 		}
-		tablets[n] = &TabletInfo{Tablet: tablet, version: listResults[n].Version}
+		if opt != nil && opt.KeyspaceShard != nil && opt.KeyspaceShard.Keyspace != "" {
+			if opt.KeyspaceShard.Keyspace != tablet.Keyspace {
+				continue
+			}
+			if opt.KeyspaceShard.Shard != "" && opt.KeyspaceShard.Shard != tablet.Shard {
+				continue
+			}
+		}
+		tablets = append(tablets, &TabletInfo{Tablet: tablet, version: listResults[n].Version})
 	}
-
 	return tablets, nil
 }