feat(bigtable): Support last_scanned_row_key in emulator (#8343)

Co-authored-by: Steve Niemitz <sniemitz@google.com>

bigtable/bttest/inmem.go

@@ -33,6 +33,7 @@ package bttest // import "cloud.google.com/go/bigtable/bttest"
 import (
 	"bytes"
 	"context"
+	"encoding/base64"
 	"encoding/binary"
 	"fmt"
 	"log"
@@ -45,6 +46,9 @@ import (
 	"sync"
 	"time"
 
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/protobuf/proto"
+
 	longrunning "cloud.google.com/go/longrunning/autogen/longrunningpb"
 	emptypb "github.com/golang/protobuf/ptypes/empty"
 	"github.com/golang/protobuf/ptypes/wrappers"
@@ -423,7 +427,31 @@ func (s *server) DeleteSnapshot(context.Context, *btapb.DeleteSnapshotRequest) (
 	return nil, status.Errorf(codes.Unimplemented, "the emulator does not currently support snapshots")
 }
 
+func featureFlagsFromContext(context context.Context) *btpb.FeatureFlags {
+	ff := &btpb.FeatureFlags{}
+
+	var md, ok = metadata.FromIncomingContext(context)
+	if !ok {
+		return ff
+	}
+
+	features := md.Get("bigtable-features")
+	if len(features) == 0 {
+		return ff
+	}
+
+	dec, err := base64.URLEncoding.DecodeString(features[0])
+	if err != nil {
+		return ff
+	}
+
+	_ = proto.Unmarshal(dec, ff)
+	return ff
+}
+
 func (s *server) ReadRows(req *btpb.ReadRowsRequest, stream btpb.Bigtable_ReadRowsServer) error {
+	featureFlags := featureFlagsFromContext(stream.Context())
+
 	start := time.Now()
 	s.mu.Lock()
 	tbl, ok := s.tables[req.TableName]
@@ -500,6 +528,10 @@ func (s *server) ReadRows(req *btpb.ReadRowsRequest, stream btpb.Bigtable_ReadRo
 		}
 	}
 	if req.Reversed {
+		if !featureFlags.ReverseScans {
+			return status.Errorf(codes.Unimplemented, "Client doesn't support reverse scans yet")
+		}
+
 		sort.Sort(sort.Reverse(byRowKey(rows)))
 	} else {
 		sort.Sort(byRowKey(rows))
@@ -517,7 +549,7 @@ func (s *server) ReadRows(req *btpb.ReadRowsRequest, stream btpb.Bigtable_ReadRo
 			break
 		}
 
-		if err := streamRow(stream, r, req.Filter, iterStats); err != nil {
+		if err := streamRow(stream, r, req.Filter, iterStats, featureFlags); err != nil {
 			return err
 		}
 	}
@@ -543,7 +575,7 @@ func (s *server) ReadRows(req *btpb.ReadRowsRequest, stream btpb.Bigtable_ReadRo
 
 // streamRow filters the given row and sends it via the given stream.
 // Returns true if at least one cell matched the filter and was streamed, false otherwise.
-func streamRow(stream btpb.Bigtable_ReadRowsServer, r *row, f *btpb.RowFilter, s *btpb.ReadIterationStats) error {
+func streamRow(stream btpb.Bigtable_ReadRowsServer, r *row, f *btpb.RowFilter, s *btpb.ReadIterationStats, ff *btpb.FeatureFlags) error {
 	r.mu.Lock()
 	nr := r.copy()
 	r.mu.Unlock()
@@ -562,6 +594,14 @@ func streamRow(stream btpb.Bigtable_ReadRowsServer, r *row, f *btpb.RowFilter, s
 		return err
 	}
 	if !match {
+		// if the client requested it, send last_scanned_row responses for rows that didn't match a filter
+		if ff.LastScannedRowResponses {
+			rrr := &btpb.ReadRowsResponse{
+				LastScannedRowKey: []byte(r.key),
+			}
+			return stream.Send(rrr)
+		}
+
 		return nil
 	}
 

bigtable/bttest/inmem_test.go

@@ -27,6 +27,9 @@ import (
 	"testing"
 	"time"
 
+	"google.golang.org/grpc/metadata"
+
+	"cloud.google.com/go/bigtable/internal/option"
 	"cloud.google.com/go/internal/testutil"
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/protobuf/ptypes/wrappers"
@@ -597,6 +600,7 @@ func TestDropRowRange(t *testing.T) {
 
 type MockReadRowsServer struct {
 	responses []*btpb.ReadRowsResponse
+	ctx       context.Context
 	grpc.ServerStream
 }
 
@@ -605,6 +609,13 @@ func (s *MockReadRowsServer) Send(resp *btpb.ReadRowsResponse) error {
 	return nil
 }
 
+func (s *MockReadRowsServer) Context() context.Context {
+	if s.ctx == nil {
+		return context.Background()
+	}
+	return s.ctx
+}
+
 func TestCheckTimestampMaxValue(t *testing.T) {
 	// Test that max Timestamp value can be passed in TimestampMicros without error
 	// and that max Timestamp is the largest valid value in Millis.
@@ -706,6 +717,64 @@ func TestReadRows(t *testing.T) {
 	}
 }
 
+func TestReadRowsLastScannedRow(t *testing.T) {
+	ctx := context.Background()
+	s := &server{
+		tables: make(map[string]*table),
+	}
+	newTbl := btapb.Table{
+		ColumnFamilies: map[string]*btapb.ColumnFamily{
+			"cf0": {GcRule: &btapb.GcRule{Rule: &btapb.GcRule_MaxNumVersions{MaxNumVersions: 1}}},
+		},
+	}
+	tblInfo, err := s.CreateTable(ctx, &btapb.CreateTableRequest{Parent: "cluster", TableId: "t", Table: &newTbl})
+	if err != nil {
+		t.Fatalf("Creating table: %v", err)
+	}
+	mreq := &btpb.MutateRowRequest{
+		TableName: tblInfo.Name,
+		RowKey:    []byte("row"),
+		Mutations: []*btpb.Mutation{{
+			Mutation: &btpb.Mutation_SetCell_{SetCell: &btpb.Mutation_SetCell{
+				FamilyName:      "cf0",
+				ColumnQualifier: []byte("col"),
+				TimestampMicros: 1000,
+				Value:           []byte{},
+			}},
+		}},
+	}
+	if _, err := s.MutateRow(ctx, mreq); err != nil {
+		t.Fatalf("Populating table: %v", err)
+	}
+
+	for _, rowset := range []*btpb.RowSet{
+		{RowKeys: [][]byte{[]byte("row")}},
+		{RowRanges: []*btpb.RowRange{{StartKey: &btpb.RowRange_StartKeyClosed{StartKeyClosed: []byte("")}}}},
+		{RowRanges: []*btpb.RowRange{{StartKey: &btpb.RowRange_StartKeyClosed{StartKeyClosed: []byte("r")}}}},
+		{RowRanges: []*btpb.RowRange{{
+			StartKey: &btpb.RowRange_StartKeyClosed{StartKeyClosed: []byte("")},
+			EndKey:   &btpb.RowRange_EndKeyOpen{EndKeyOpen: []byte("s")},
+		}}},
+	} {
+		featureFlags := option.WithFeatureFlags()
+		ctx := metadata.NewIncomingContext(context.Background(), featureFlags)
+
+		mock := &MockReadRowsServer{ctx: ctx}
+		filter := &btpb.RowFilter{Filter: &btpb.RowFilter_BlockAllFilter{BlockAllFilter: true}}
+		req := &btpb.ReadRowsRequest{TableName: tblInfo.Name, Rows: rowset, Filter: filter}
+		if err = s.ReadRows(req, mock); err != nil {
+			t.Fatalf("ReadRows error: %v", err)
+		}
+		if got, want := len(mock.responses), 1; got != want {
+			t.Errorf("%+v: response count: got %d, want %d", rowset, got, want)
+		}
+		expect := &btpb.ReadRowsResponse{LastScannedRowKey: []byte("row")}
+		if !proto.Equal(mock.responses[0], expect) {
+			t.Errorf("%+v: response: got %+v, want %+v", rowset, mock.responses[0], expect)
+		}
+	}
+}
+
 func TestReadRowsError(t *testing.T) {
 	ctx := context.Background()
 	s := &server{
@@ -1093,7 +1162,8 @@ func TestReadRowsReversed(t *testing.T) {
 		}
 	}
 
-	rrss := new(MockReadRowsServer)
+	serverCtx := metadata.NewIncomingContext(context.Background(), option.WithFeatureFlags())
+	rrss := &MockReadRowsServer{ctx: serverCtx}
 	rreq := &btpb.ReadRowsRequest{TableName: tbl.Name, Reversed: true}
 	if err := srv.ReadRows(rreq, rrss); err != nil {
 		t.Fatalf("Failed to read rows: %v", err)

bigtable/bttest/validation_test.go

@@ -164,7 +164,8 @@ func TestValidateReadRowsRequestSendsRPCError(t *testing.T) {
 			},
 		}
 
-		err := srv.ReadRows(badReq, nil)
+		stream := &MockReadRowsServer{}
+		err := srv.ReadRows(badReq, stream)
 		if err == nil {
 			t.Errorf("#%d: unexpectedly returned nil error", i)
 			continue

bigtable/go.mod

@@ -3,31 +3,31 @@ module cloud.google.com/go/bigtable
 go 1.19
 
 require (
-	cloud.google.com/go v0.110.2
-	cloud.google.com/go/iam v1.1.0
-	cloud.google.com/go/longrunning v0.5.0
+	cloud.google.com/go v0.110.4
+	cloud.google.com/go/iam v1.1.1
+	cloud.google.com/go/longrunning v0.5.1
 	github.com/golang/protobuf v1.5.3
 	github.com/google/btree v1.1.2
 	github.com/google/go-cmp v0.5.9
 	github.com/googleapis/cloud-bigtable-clients-test v0.0.0-20230505150253-16eeee810d3a
 	github.com/googleapis/gax-go/v2 v2.11.0
 	google.golang.org/api v0.126.0
-	google.golang.org/genproto v0.0.0-20230629202037-9506855d4529
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20230629202037-9506855d4529
-	google.golang.org/grpc v1.55.0
-	google.golang.org/protobuf v1.30.0
+	google.golang.org/genproto v0.0.0-20230726155614-23370e0ffb3e
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20230706204954-ccb25ca9f130
+	google.golang.org/grpc v1.56.2
+	google.golang.org/protobuf v1.31.0
 	rsc.io/binaryregexp v0.2.0
 )
 
 require (
-	cloud.google.com/go/compute v1.19.3 // indirect
+	cloud.google.com/go/compute v1.20.1 // indirect
 	cloud.google.com/go/compute/metadata v0.2.3 // indirect
 	github.com/census-instrumentation/opencensus-proto v0.4.1 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/cncf/udpa/go v0.0.0-20220112060539-c52dc94e7fbe // indirect
-	github.com/cncf/xds/go v0.0.0-20230310173818-32f1caf87195 // indirect
-	github.com/envoyproxy/go-control-plane v0.11.0 // indirect
-	github.com/envoyproxy/protoc-gen-validate v0.10.0 // indirect
+	github.com/cncf/xds/go v0.0.0-20230607035331-e9ce68804cb4 // indirect
+	github.com/envoyproxy/go-control-plane v0.11.1-0.20230524094728-9239064ad72f // indirect
+	github.com/envoyproxy/protoc-gen-validate v0.10.1 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/google/s2a-go v0.1.4 // indirect
 	github.com/google/uuid v1.3.0 // indirect
@@ -40,5 +40,5 @@ require (
 	golang.org/x/text v0.9.0 // indirect
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
-	google.golang.org/genproto/googleapis/api v0.0.0-20230629202037-9506855d4529 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20230706204954-ccb25ca9f130 // indirect
 )

bigtable/go.sum

@@ -1,15 +1,15 @@
 cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
-cloud.google.com/go v0.110.2 h1:sdFPBr6xG9/wkBbfhmUz/JmZC7X6LavQgcrVINrKiVA=
-cloud.google.com/go v0.110.2/go.mod h1:k04UEeEtb6ZBRTv3dZz4CeJC3jKGxyhl0sAiVVquxiw=
-cloud.google.com/go/compute v1.19.3 h1:DcTwsFgGev/wV5+q8o2fzgcHOaac+DKGC91ZlvpsQds=
-cloud.google.com/go/compute v1.19.3/go.mod h1:qxvISKp/gYnXkSAD1ppcSOveRAmzxicEv/JlizULFrI=
+cloud.google.com/go v0.110.4 h1:1JYyxKMN9hd5dR2MYTPWkGUgcoxVVhg0LKNKEo0qvmk=
+cloud.google.com/go v0.110.4/go.mod h1:+EYjdK8e5RME/VY/qLCAtuyALQ9q67dvuum8i+H5xsI=
+cloud.google.com/go/compute v1.20.1 h1:6aKEtlUiwEpJzM001l0yFkpXmUVXaN8W+fbkb2AZNbg=
+cloud.google.com/go/compute v1.20.1/go.mod h1:4tCnrn48xsqlwSAiLf1HXMQk8CONslYbdiEZc9FEIbM=
 cloud.google.com/go/compute/metadata v0.2.3 h1:mg4jlk7mCAj6xXp9UJ4fjI9VUI5rubuGBW5aJ7UnBMY=
 cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=
-cloud.google.com/go/iam v1.1.0 h1:67gSqaPukx7O8WLLHMa0PNs3EBGd2eE4d+psbO/CO94=
-cloud.google.com/go/iam v1.1.0/go.mod h1:nxdHjaKfCr7fNYx/HJMM8LgiMugmveWlkatear5gVyk=
-cloud.google.com/go/longrunning v0.5.0 h1:DK8BH0+hS+DIvc9a2TPnteUievsTCH4ORMAASSb7JcQ=
-cloud.google.com/go/longrunning v0.5.0/go.mod h1:0JNuqRShmscVAhIACGtskSAWtqtOoPkwP0YF1oVEchc=
+cloud.google.com/go/iam v1.1.1 h1:lW7fzj15aVIXYHREOqjRBV9PsH0Z6u8Y46a1YGvQP4Y=
+cloud.google.com/go/iam v1.1.1/go.mod h1:A5avdyVL2tCppe4unb0951eI9jreack+RJ0/d+KUZOU=
+cloud.google.com/go/longrunning v0.5.1 h1:Fr7TXftcqTudoyRJa113hyaqlGdiBQkp0Gq7tErFDWI=
+cloud.google.com/go/longrunning v0.5.1/go.mod h1:spvimkwdz6SPWKEt/XBij79E9fiTkHSQl/fRUUQJYJc=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
@@ -27,20 +27,20 @@ github.com/cncf/udpa/go v0.0.0-20220112060539-c52dc94e7fbe/go.mod h1:6pvJx4me5XP
 github.com/cncf/xds/go v0.0.0-20210805033703-aa0b78936158/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20210922020428-25de7278fc84/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
-github.com/cncf/xds/go v0.0.0-20230310173818-32f1caf87195 h1:58f1tJ1ra+zFINPlwLWvQsR9CzAKt2e+EWV2yX9oXQ4=
-github.com/cncf/xds/go v0.0.0-20230310173818-32f1caf87195/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
+github.com/cncf/xds/go v0.0.0-20230607035331-e9ce68804cb4 h1:/inchEIKaYC1Akx+H+gqO04wryn5h75LSazbRlnya1k=
+github.com/cncf/xds/go v0.0.0-20230607035331-e9ce68804cb4/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=
 github.com/envoyproxy/go-control-plane v0.9.9-0.20201210154907-fd9021fe5dad/go.mod h1:cXg6YxExXjJnVBQHBLXeUAgxn2UodCpnH306RInaBQk=
 github.com/envoyproxy/go-control-plane v0.9.10-0.20210907150352-cf90f659a021/go.mod h1:AFq3mo9L8Lqqiid3OhADV3RfLJnjiw63cSpi+fDTRC0=
-github.com/envoyproxy/go-control-plane v0.11.0 h1:jtLewhRR2vMRNnq2ZZUoCjUlgut+Y0+sDDWPOfwOi1o=
-github.com/envoyproxy/go-control-plane v0.11.0/go.mod h1:VnHyVMpzcLvCFt9yUz1UnCwHLhwx1WguiVDV7pTG/tI=
+github.com/envoyproxy/go-control-plane v0.11.1-0.20230524094728-9239064ad72f h1:7T++XKzy4xg7PKy+bM+Sa9/oe1OC88yz2hXQUISoXfA=
+github.com/envoyproxy/go-control-plane v0.11.1-0.20230524094728-9239064ad72f/go.mod h1:sfYdkwUW4BA3PbKjySwjJy+O4Pu0h62rlqCMHNk+K+Q=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
-github.com/envoyproxy/protoc-gen-validate v0.10.0 h1:oIfnZFdC0YhpNNEX+SuIqko4cqqVZeN9IGTrhZje83Y=
-github.com/envoyproxy/protoc-gen-validate v0.10.0/go.mod h1:DRjgyB0I43LtJapqN6NiRwroiAU2PaFuvk/vjgh61ss=
+github.com/envoyproxy/protoc-gen-validate v0.10.1 h1:c0g45+xCJhdgFGw7a5QAfdS4byAbud7miNWJ1WwEVf8=
+github.com/envoyproxy/protoc-gen-validate v0.10.1/go.mod h1:DRjgyB0I43LtJapqN6NiRwroiAU2PaFuvk/vjgh61ss=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
@@ -181,12 +181,12 @@ google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoA
 google.golang.org/genproto v0.0.0-20190819201941-24fa4b261c55/go.mod h1:DMBHOl98Agz4BDEuKkezgsaosCRResVns1a3J2ZsMNc=
 google.golang.org/genproto v0.0.0-20200513103714-09dca8ec2884/go.mod h1:55QSHmfGQM9UVYDPBsyGGes0y52j32PQ3BqQfXhyH3c=
 google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013/go.mod h1:NbSheEEYHJ7i3ixzK3sjbqSGDJWnxyFXZblF3eUsNvo=
-google.golang.org/genproto v0.0.0-20230629202037-9506855d4529 h1:9JucMWR7sPvCxUFd6UsOUNmA5kCcWOfORaT3tpAsKQs=
-google.golang.org/genproto v0.0.0-20230629202037-9506855d4529/go.mod h1:xZnkP7mREFX5MORlOPEzLMr+90PPZQ2QWzrVTWfAq64=
-google.golang.org/genproto/googleapis/api v0.0.0-20230629202037-9506855d4529 h1:s5YSX+ZH5b5vS9rnpGymvIyMpLRJizowqDlOuyjXnTk=
-google.golang.org/genproto/googleapis/api v0.0.0-20230629202037-9506855d4529/go.mod h1:vHYtlOoi6TsQ3Uk2yxR7NI5z8uoV+3pZtR4jmHIkRig=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20230629202037-9506855d4529 h1:DEH99RbiLZhMxrpEJCZ0A+wdTe0EOgou/poSLx9vWf4=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20230629202037-9506855d4529/go.mod h1:66JfowdXAEgad5O9NnYcsNPLCPZJD++2L9X0PCMODrA=
+google.golang.org/genproto v0.0.0-20230726155614-23370e0ffb3e h1:xIXmWJ303kJCuogpj0bHq+dcjcZHU+XFyc1I0Yl9cRg=
+google.golang.org/genproto v0.0.0-20230726155614-23370e0ffb3e/go.mod h1:0ggbjUrZYpy1q+ANUS30SEoGZ53cdfwtbuG7Ptgy108=
+google.golang.org/genproto/googleapis/api v0.0.0-20230706204954-ccb25ca9f130 h1:XVeBY8d/FaK4848myy41HBqnDwvxeV3zMZhwN1TvAMU=
+google.golang.org/genproto/googleapis/api v0.0.0-20230706204954-ccb25ca9f130/go.mod h1:mPBs5jNgx2GuQGvFwUvVKqtn6HsUw9nP64BedgvqEsQ=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20230706204954-ccb25ca9f130 h1:2FZP5XuJY9zQyGM5N0rtovnoXjiMUEIUMvw0m9wlpLc=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20230706204954-ccb25ca9f130/go.mod h1:8mL13HKkDa+IuJ8yruA3ci0q+0vsUz4m//+ottjwS5o=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.23.0/go.mod h1:Y5yQAOtifL1yxbo5wqy6BxZv8vAUGQwXBOALyacEbxg=
 google.golang.org/grpc v1.25.1/go.mod h1:c3i+UQWmh7LiEpx4sFZnkU36qjEYZ0imhYfXVyQciAY=
@@ -195,8 +195,8 @@ google.golang.org/grpc v1.33.1/go.mod h1:fr5YgcSWrqhRRxogOsw7RzIpsmvOZ6IcH4kBYTp
 google.golang.org/grpc v1.33.2/go.mod h1:JMHMWHQWaTccqQQlmk3MJZS+GWXOdAesneDmEnv2fbc=
 google.golang.org/grpc v1.36.0/go.mod h1:qjiiYl8FncCW8feJPdyg3v6XW24KsRHe+dy9BAGRRjU=
 google.golang.org/grpc v1.45.0/go.mod h1:lN7owxKUQEqMfSyQikvvk5tf/6zMPsrK+ONuO11+0rQ=
-google.golang.org/grpc v1.55.0 h1:3Oj82/tFSCeUrRTg/5E/7d/W5A1tj6Ky1ABAuZuv5ag=
-google.golang.org/grpc v1.55.0/go.mod h1:iYEXKGkEBhg1PjZQvoYEVPTDkHo1/bjTnfwTeGONTY8=
+google.golang.org/grpc v1.56.2 h1:fVRFRnXvU+x6C4IlHZewvJOVHoOv1TUuQyoRsYnB4bI=
+google.golang.org/grpc v1.56.2/go.mod h1:I9bI3vqKfayGqPUAwGdOSu7kt6oIJLixfffKrpXqQ9s=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
 google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQJ+fmap5saPgwCLgHXTUD7jkjRqWcaiX5VyM=
@@ -208,8 +208,8 @@ google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpAD
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
-google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+google.golang.org/protobuf v1.31.0 h1:g0LDEJHgrBl9N9r17Ru3sqWhkIx2NB67okBHPwC7hs8=
+google.golang.org/protobuf v1.31.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.3/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

bigtable/internal/option/option.go

@@ -19,9 +19,13 @@ package option
 
 import (
 	"context"
+	"encoding/base64"
 	"fmt"
 	"os"
 
+	btpb "google.golang.org/genproto/googleapis/bigtable/v2"
+	"google.golang.org/protobuf/proto"
+
 	"cloud.google.com/go/internal/version"
 	gax "github.com/googleapis/gax-go/v2"
 	"google.golang.org/api/option"
@@ -59,6 +63,25 @@ func withGoogleClientInfo() metadata.MD {
 	return metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
+func makeFeatureFlags() string {
+	ff := btpb.FeatureFlags{ReverseScans: true, LastScannedRowResponses: true}
+	b, err := proto.Marshal(&ff)
+	if err != nil {
+		return ""
+	}
+
+	return base64.URLEncoding.EncodeToString(b)
+}
+
+var featureFlags = makeFeatureFlags()
+
+// WithFeatureFlags set the feature flags the client supports in the
+// `bigtable-features` header sent on each request. Intended for
+// use by Google-written clients.
+func WithFeatureFlags() metadata.MD {
+	return metadata.Pairs("bigtable-features", featureFlags)
+}
+
 // streamInterceptor intercepts the creation of ClientStream within the bigtable
 // client to inject Google client information into the context metadata for
 // streaming RPCs.