Golang roachpb.RKey函數代碼示例

// TestRangeCacheClearOverlappingMeta prevents regression of a bug which caused
// a panic when clearing overlapping descriptors for [KeyMin, Meta2Key). The
// issue was that when attempting to clear out descriptors which were subsumed
// by the above range, an iteration over the corresponding meta keys was
// performed, with the left endpoint excluded. This exclusion was incorrect: it
// first incremented the start key (KeyMin) and then formed the meta key; for
// KeyMin this leads to Meta2Prefix\x00. For the above EndKey, the meta key is
// a Meta1key which sorts before Meta2Prefix\x00, causing a panic. The fix was
// simply to increment the meta key for StartKey, not StartKey itself.
func TestRangeCacheClearOverlappingMeta(t *testing.T) {
	defer leaktest.AfterTest(t)()

	firstDesc := &roachpb.RangeDescriptor{
		StartKey: roachpb.RKeyMin,
		EndKey:   roachpb.RKey("zzz"),
	}
	restDesc := &roachpb.RangeDescriptor{
		StartKey: firstDesc.StartKey,
		EndKey:   roachpb.RKeyMax,
	}

	cache := newRangeDescriptorCache(nil, 2<<10)
	cache.rangeCache.cache.Add(rangeCacheKey(keys.RangeMetaKey(firstDesc.EndKey)),
		firstDesc)
	cache.rangeCache.cache.Add(rangeCacheKey(keys.RangeMetaKey(restDesc.EndKey)),
		restDesc)

	// Add new range, corresponding to splitting the first range at a meta key.
	metaSplitDesc := &roachpb.RangeDescriptor{
		StartKey: roachpb.RKeyMin,
		EndKey:   mustMeta(roachpb.RKey("foo")),
	}
	func() {
		defer func() {
			if r := recover(); r != nil {
				t.Fatalf("invocation of clearOverlappingCachedRangeDescriptors panicked: %v", r)
			}
		}()
		if err := cache.clearOverlappingCachedRangeDescriptors(metaSplitDesc); err != nil {
			t.Fatal(err)
		}
	}()
}

// TestRangeSplitMeta executes various splits (including at meta addressing)
// and checks that all created intents are resolved. This includes both intents
// which are resolved synchronously with EndTransaction and via RPC.
func TestRangeSplitMeta(t *testing.T) {
	defer leaktest.AfterTest(t)
	s := createTestDB(t)
	defer s.Stop()

	splitKeys := []roachpb.RKey{roachpb.RKey("G"), meta(roachpb.RKey("F")),
		meta(roachpb.RKey("K")), meta(roachpb.RKey("H"))}

	// Execute the consecutive splits.
	for _, splitKey := range splitKeys {
		log.Infof("starting split at key %q...", splitKey)
		if err := s.DB.AdminSplit(roachpb.Key(splitKey)); err != nil {
			t.Fatal(err)
		}
		log.Infof("split at key %q complete", splitKey)
	}

	if err := util.IsTrueWithin(func() bool {
		if _, _, err := engine.MVCCScan(s.Eng, keys.LocalMax, roachpb.KeyMax, 0, roachpb.MaxTimestamp, true, nil); err != nil {
			log.Infof("mvcc scan should be clean: %s", err)
			return false
		}
		return true
	}, 500*time.Millisecond); err != nil {
		t.Error("failed to verify no dangling intents within 500ms")
	}
}

// newTestRangeSet creates a new range set that has the count number of ranges.
func newTestRangeSet(count int, t *testing.T) *testRangeSet {
	rs := &testRangeSet{replicasByKey: btree.New(64 /* degree */)}
	for i := 0; i < count; i++ {
		desc := &roachpb.RangeDescriptor{
			RangeID:  roachpb.RangeID(i),
			StartKey: roachpb.RKey(fmt.Sprintf("%03d", i)),
			EndKey:   roachpb.RKey(fmt.Sprintf("%03d", i+1)),
		}
		// Initialize the range stat so the scanner can use it.
		rng := &Replica{
			RangeID: desc.RangeID,
		}
		rng.mu.state.Stats = enginepb.MVCCStats{
			KeyBytes:  1,
			ValBytes:  2,
			KeyCount:  1,
			LiveCount: 1,
		}

		if err := rng.setDesc(desc); err != nil {
			t.Fatal(err)
		}
		if exRngItem := rs.replicasByKey.ReplaceOrInsert(rng); exRngItem != nil {
			t.Fatalf("failed to insert range %s", rng)
		}
	}
	return rs
}

// TestStoreRangeUpReplicate verifies that the replication queue will notice
// under-replicated ranges and replicate them.
func TestStoreRangeUpReplicate(t *testing.T) {
	defer leaktest.AfterTest(t)
	mtc := startMultiTestContext(t, 3)
	defer mtc.Stop()

	// Initialize the gossip network.
	var wg sync.WaitGroup
	wg.Add(len(mtc.stores))
	key := gossip.MakePrefixPattern(gossip.KeyStorePrefix)
	mtc.stores[0].Gossip().RegisterCallback(key, func(_ string, _ roachpb.Value) { wg.Done() })
	for _, s := range mtc.stores {
		s.GossipStore()
	}
	wg.Wait()

	// Once we know our peers, trigger a scan.
	mtc.stores[0].ForceReplicationScanAndProcess()

	// The range should become available on every node.
	if err := util.IsTrueWithin(func() bool {
		for _, s := range mtc.stores {
			r := s.LookupReplica(roachpb.RKey("a"), roachpb.RKey("b"))
			if r == nil {
				return false
			}
		}
		return true
	}, replicationTimeout); err != nil {
		t.Fatal(err)
	}
}

// Addr returns the address for the key, used to lookup the range containing
// the key. In the normal case, this is simply the key's value. However, for
// local keys, such as transaction records, range-spanning binary tree node
// pointers, the address is the inner encoded key, with the local key prefix
// and the suffix and optional detail removed. This address unwrapping is
// performed repeatedly in the case of doubly-local keys. In this way, local
// keys address to the same range as non-local keys, but are stored separately
// so that they don't collide with user-space or global system keys.
//
// However, not all local keys are addressable in the global map. Only range
// local keys incorporating a range key (start key or transaction key) are
// addressable (e.g. range metadata and txn records). Range local keys
// incorporating the Range ID are not (e.g. abort cache entries, and range
// stats).
func Addr(k roachpb.Key) (roachpb.RKey, error) {
	if !bytes.HasPrefix(k, localPrefix) {
		return roachpb.RKey(k), nil
	}

	for {
		if bytes.HasPrefix(k, localStorePrefix) {
			return nil, errors.Errorf("store-local key %q is not addressable", k)
		}
		if bytes.HasPrefix(k, LocalRangeIDPrefix) {
			return nil, errors.Errorf("local range ID key %q is not addressable", k)
		}
		if !bytes.HasPrefix(k, LocalRangePrefix) {
			return nil, errors.Errorf("local key %q malformed; should contain prefix %q",
				k, LocalRangePrefix)
		}
		k = k[len(LocalRangePrefix):]
		var err error
		// Decode the encoded key, throw away the suffix and detail.
		if _, k, err = encoding.DecodeBytesAscending(k, nil); err != nil {
			return nil, err
		}
		if !bytes.HasPrefix(k, localPrefix) {
			break
		}
	}
	return roachpb.RKey(k), nil
}

// TestStoreRangeUpReplicate verifies that the replication queue will notice
// under-replicated ranges and replicate them.
func TestStoreRangeUpReplicate(t *testing.T) {
	defer leaktest.AfterTest(t)()
	mtc := startMultiTestContext(t, 3)
	defer mtc.Stop()

	// Initialize the gossip network.
	var wg sync.WaitGroup
	wg.Add(len(mtc.stores))
	key := gossip.MakePrefixPattern(gossip.KeyStorePrefix)
	mtc.stores[0].Gossip().RegisterCallback(key, func(_ string, _ roachpb.Value) { wg.Done() })
	for _, s := range mtc.stores {
		s.GossipStore()
	}
	wg.Wait()

	// Once we know our peers, trigger a scan.
	mtc.stores[0].ForceReplicationScanAndProcess()

	// The range should become available on every node.
	util.SucceedsSoon(t, func() error {
		for _, s := range mtc.stores {
			r := s.LookupReplica(roachpb.RKey("a"), roachpb.RKey("b"))
			if r == nil {
				return util.Errorf("expected replica for keys \"a\" - \"b\"")
			}
		}
		return nil
	})
}

func TestComputeStatsForKeySpan(t *testing.T) {
	defer leaktest.AfterTest(t)()
	mtc := startMultiTestContext(t, 3)
	defer mtc.Stop()

	// Create a number of ranges using splits.
	splitKeys := []string{"a", "c", "e", "g", "i"}
	for _, k := range splitKeys {
		key := []byte(k)
		repl := mtc.stores[0].LookupReplica(key, roachpb.RKeyMin)
		args := adminSplitArgs(key, key)
		header := roachpb.Header{
			RangeID: repl.RangeID,
		}
		if _, err := client.SendWrappedWith(mtc.stores[0], nil, header, &args); err != nil {
			t.Fatal(err)
		}
	}

	// Wait for splits to finish.
	util.SucceedsSoon(t, func() error {
		repl := mtc.stores[0].LookupReplica(roachpb.RKey("z"), nil)
		if actualRSpan := repl.Desc().RSpan(); !actualRSpan.Key.Equal(roachpb.RKey("i")) {
			return errors.Errorf("expected range %s to begin at key 'i'", repl)
		}
		return nil
	})

	// Create some keys across the ranges.
	incKeys := []string{"b", "bb", "bbb", "d", "dd", "h"}
	for _, k := range incKeys {
		if _, err := mtc.dbs[0].Inc([]byte(k), 5); err != nil {
			t.Fatal(err)
		}
	}

	// Verify stats across different spans.
	for _, tcase := range []struct {
		startKey       string
		endKey         string
		expectedRanges int
		expectedKeys   int64
	}{
		{"a", "i", 4, 6},
		{"a", "c", 1, 3},
		{"b", "e", 2, 5},
		{"e", "i", 2, 1},
	} {
		start, end := tcase.startKey, tcase.endKey
		stats, count := mtc.stores[0].ComputeStatsForKeySpan(
			roachpb.RKey(start), roachpb.RKey(end))
		if a, e := count, tcase.expectedRanges; a != e {
			t.Errorf("Expected %d ranges in span [%s - %s], found %d", e, start, end, a)
		}
		if a, e := stats.LiveCount, tcase.expectedKeys; a != e {
			t.Errorf("Expected %d keys in span [%s - %s], found %d", e, start, end, a)
		}
	}
}

// TestSendRPCRetry verifies that sendRPC failed on first address but succeed on
// second address, the second reply should be successfully returned back.
func TestSendRPCRetry(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	g.SetNodeID(1)
	if err := g.SetNodeDescriptor(&roachpb.NodeDescriptor{NodeID: 1}); err != nil {
		t.Fatal(err)
	}
	// Fill RangeDescriptor with 2 replicas
	var descriptor = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKey("z"),
	}
	for i := 1; i <= 2; i++ {
		addr := util.MakeUnresolvedAddr("tcp", fmt.Sprintf("node%d", i))
		nd := &roachpb.NodeDescriptor{
			NodeID:  roachpb.NodeID(i),
			Address: util.MakeUnresolvedAddr(addr.Network(), addr.String()),
		}
		if err := g.AddInfoProto(gossip.MakeNodeIDKey(roachpb.NodeID(i)), nd, time.Hour); err != nil {
			t.Fatal(err)
		}

		descriptor.Replicas = append(descriptor.Replicas, roachpb.ReplicaDescriptor{
			NodeID:  roachpb.NodeID(i),
			StoreID: roachpb.StoreID(i),
		})
	}
	// Define our rpcSend stub which returns success on the second address.
	var testFn rpcSendFn = func(_ rpc.Options, method string, addrs []net.Addr, getArgs func(addr net.Addr) proto.Message, getReply func() proto.Message, _ *rpc.Context) ([]proto.Message, error) {
		if method == "Node.Batch" {
			// reply from first address failed
			_ = getReply()
			// reply from second address succeed
			batchReply := getReply().(*roachpb.BatchResponse)
			reply := &roachpb.ScanResponse{}
			batchReply.Add(reply)
			reply.Rows = append([]roachpb.KeyValue{}, roachpb.KeyValue{Key: roachpb.Key("b"), Value: roachpb.Value{}})
			return []proto.Message{batchReply}, nil
		}
		return nil, util.Errorf("unexpected method %v", method)
	}
	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(_ roachpb.RKey, _, _ bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			return []roachpb.RangeDescriptor{descriptor}, nil
		}),
	}
	ds := NewDistSender(ctx, g)
	scan := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("d"), 1)
	sr, err := client.SendWrapped(ds, nil, scan)
	if err != nil {
		t.Fatal(err)
	}
	if l := len(sr.(*roachpb.ScanResponse).Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
}

func localRangeIDKeyParse(input string) (remainder string, key roachpb.Key) {
	var rangeID int64
	var err error
	input = mustShiftSlash(input)
	if endPos := strings.Index(input, "/"); endPos > 0 {
		rangeID, err = strconv.ParseInt(input[:endPos], 10, 64)
		if err != nil {
			panic(err)
		}
		input = input[endPos:]
	} else {
		panic(errors.Errorf("illegal RangeID: %q", input))
	}
	input = mustShiftSlash(input)
	var infix string
	infix, input = mustShift(input)
	var replicated bool
	switch {
	case bytes.Equal(localRangeIDUnreplicatedInfix, []byte(infix)):
	case bytes.Equal(localRangeIDReplicatedInfix, []byte(infix)):
		replicated = true
	default:
		panic(errors.Errorf("invalid infix: %q", infix))
	}

	input = mustShiftSlash(input)
	// Get the suffix.
	var suffix roachpb.RKey
	for _, s := range rangeIDSuffixDict {
		if strings.HasPrefix(input, s.name) {
			input = input[len(s.name):]
			if s.psFunc != nil {
				remainder, key = s.psFunc(roachpb.RangeID(rangeID), input)
				return
			}
			suffix = roachpb.RKey(s.suffix)
			break
		}
	}
	maker := MakeRangeIDUnreplicatedKey
	if replicated {
		maker = MakeRangeIDReplicatedKey
	}
	if suffix != nil {
		if input != "" {
			panic(&errUglifyUnsupported{errors.New("nontrivial detail")})
		}
		var detail roachpb.RKey
		// TODO(tschottdorf): can't do this, init cycle:
		// detail, err := UglyPrint(input)
		// if err != nil {
		// 	return "", nil, err
		// }
		remainder = ""
		key = maker(roachpb.RangeID(rangeID), suffix, roachpb.RKey(detail))
		return
	}
	panic(&errUglifyUnsupported{errors.New("unhandled general range key")})
}

// TestUpdateRangeAddressingSplitMeta1 verifies that it's an error to
// attempt to update range addressing records that would allow a split
// of meta1 records.
func TestUpdateRangeAddressingSplitMeta1(t *testing.T) {
	defer leaktest.AfterTest(t)
	left := &roachpb.RangeDescriptor{StartKey: roachpb.RKeyMin, EndKey: meta1Key(roachpb.RKey("a"))}
	right := &roachpb.RangeDescriptor{StartKey: meta1Key(roachpb.RKey("a")), EndKey: roachpb.RKeyMax}
	if err := splitRangeAddressing(&client.Batch{}, left, right); err == nil {
		t.Error("expected failure trying to update addressing records for meta1 split")
	}
}

// TestChangeReplicasDuplicateError tests that a replica change aborts if
// another change has been made to the RangeDescriptor since it was initiated.
func TestChangeReplicasDescriptorInvariant(t *testing.T) {
	defer leaktest.AfterTest(t)
	mtc := startMultiTestContext(t, 3)
	defer mtc.Stop()

	repl, err := mtc.stores[0].GetReplica(1)
	if err != nil {
		t.Fatal(err)
	}

	addReplica := func(storeNum int, desc *roachpb.RangeDescriptor) error {
		return repl.ChangeReplicas(roachpb.ADD_REPLICA,
			roachpb.ReplicaDescriptor{
				NodeID:  mtc.stores[storeNum].Ident.NodeID,
				StoreID: mtc.stores[storeNum].Ident.StoreID,
			},
			desc)
	}

	// Retain the descriptor for the range at this point.
	origDesc := repl.Desc()

	// Add replica to the second store, which should succeed.
	if err := addReplica(1, origDesc); err != nil {
		t.Fatal(err)
	}
	if err := util.IsTrueWithin(func() bool {
		r := mtc.stores[1].LookupReplica(roachpb.RKey("a"), roachpb.RKey("b"))
		if r == nil {
			return false
		}
		return true
	}, time.Second); err != nil {
		t.Fatal(err)
	}

	// Attempt to add replica to the third store with the original descriptor.
	// This should fail because the descriptor is stale.
	if err := addReplica(2, origDesc); err == nil {
		t.Fatal("Expected error calling ChangeReplicas with stale RangeDescriptor")
	}

	// Add to third store with fresh descriptor.
	if err := addReplica(2, repl.Desc()); err != nil {
		t.Fatal(err)
	}
	if err := util.IsTrueWithin(func() bool {
		r := mtc.stores[2].LookupReplica(roachpb.RKey("a"), roachpb.RKey("b"))
		if r == nil {
			return false
		}
		return true
	}, time.Second); err != nil {
		t.Fatal(err)
	}
}

func initTestDescriptorDB(t *testing.T) *testDescriptorDB {
	db := newTestDescriptorDB()
	for i, char := range "abcdefghijklmnopqrstuvwx" {
		db.splitRange(t, roachpb.RKey(string(char)))
		if i > 0 && i%6 == 0 {
			db.splitRange(t, mustMeta(roachpb.RKey(string(char))))
		}
	}
	db.cache = newRangeDescriptorCache(db, 2<<10)
	return db
}

// TestReplicateAfterSplit verifies that a new replica whose start key
// is not KeyMin replicating to a fresh store can apply snapshots correctly.
func TestReplicateAfterSplit(t *testing.T) {
	defer leaktest.AfterTest(t)
	mtc := startMultiTestContext(t, 2)
	defer mtc.Stop()

	rangeID := roachpb.RangeID(1)
	splitKey := roachpb.Key("m")
	key := roachpb.Key("z")

	store0 := mtc.stores[0]
	// Make the split
	splitArgs := adminSplitArgs(roachpb.KeyMin, splitKey)
	if _, err := client.SendWrapped(rg1(store0), nil, &splitArgs); err != nil {
		t.Fatal(err)
	}

	rangeID2 := store0.LookupReplica(roachpb.RKey(key), nil).RangeID
	if rangeID2 == rangeID {
		t.Errorf("got same range id after split")
	}
	// Issue an increment for later check.
	incArgs := incrementArgs(key, 11)
	if _, err := client.SendWrappedWith(rg1(store0), nil, roachpb.Header{
		RangeID: rangeID2,
	}, &incArgs); err != nil {
		t.Fatal(err)
	}
	// Now add the second replica.
	mtc.replicateRange(rangeID2, 0, 1)

	if mtc.stores[1].LookupReplica(roachpb.RKey(key), nil).GetMaxBytes() == 0 {
		t.Error("Range MaxBytes is not set after snapshot applied")
	}
	// Once it catches up, the effects of increment commands can be seen.
	if err := util.IsTrueWithin(func() bool {
		getArgs := getArgs(key)
		// Reading on non-leader replica should use inconsistent read
		reply, err := client.SendWrappedWith(rg1(mtc.stores[1]), nil, roachpb.Header{
			RangeID:         rangeID2,
			ReadConsistency: roachpb.INCONSISTENT,
		}, &getArgs)
		if err != nil {
			return false
		}
		getResp := reply.(*roachpb.GetResponse)
		if log.V(1) {
			log.Infof("read value %d", mustGetInt(getResp.Value))
		}
		return mustGetInt(getResp.Value) == 11
	}, replicaReadTimeout); err != nil {
		t.Fatal(err)
	}
}

// TestBatchPrevNext tests batch.{Prev,Next}.
func TestBatchPrevNext(t *testing.T) {
	defer leaktest.AfterTest(t)()
	loc := func(s string) string {
		return string(keys.RangeDescriptorKey(roachpb.RKey(s)))
	}
	span := func(strs ...string) []roachpb.Span {
		var r []roachpb.Span
		for i, str := range strs {
			if i%2 == 0 {
				r = append(r, roachpb.Span{Key: roachpb.Key(str)})
			} else {
				r[len(r)-1].EndKey = roachpb.Key(str)
			}
		}
		return r
	}
	max, min := string(roachpb.RKeyMax), string(roachpb.RKeyMin)
	abc := span("a", "", "b", "", "c", "")
	testCases := []struct {
		spans             []roachpb.Span
		key, expFW, expBW string
	}{
		{spans: span("a", "c", "b", ""), key: "b", expFW: "b", expBW: "b"},
		{spans: span("a", "c", "b", ""), key: "a", expFW: "a", expBW: "a"},
		{spans: span("a", "c", "d", ""), key: "c", expFW: "d", expBW: "c"},
		{spans: span("a", "c\x00", "d", ""), key: "c", expFW: "c", expBW: "c"},
		{spans: abc, key: "b", expFW: "b", expBW: "b"},
		{spans: abc, key: "b\x00", expFW: "c", expBW: "b\x00"},
		{spans: abc, key: "bb", expFW: "c", expBW: "b"},
		{spans: span(), key: "whatevs", expFW: max, expBW: min},
		{spans: span(loc("a"), loc("c")), key: "c", expFW: "c", expBW: "c"},
		{spans: span(loc("a"), loc("c")), key: "c\x00", expFW: max, expBW: "c\x00"},
	}

	for i, test := range testCases {
		var ba roachpb.BatchRequest
		for _, span := range test.spans {
			args := &roachpb.ScanRequest{}
			args.Key, args.EndKey = span.Key, span.EndKey
			ba.Add(args)
		}
		if next, err := next(ba, roachpb.RKey(test.key)); err != nil {
			t.Errorf("%d: %v", i, err)
		} else if !bytes.Equal(next, roachpb.Key(test.expFW)) {
			t.Errorf("%d: next: expected %q, got %q", i, test.expFW, next)
		}
		if prev, err := prev(ba, roachpb.RKey(test.key)); err != nil {
			t.Errorf("%d: %v", i, err)
		} else if !bytes.Equal(prev, roachpb.Key(test.expBW)) {
			t.Errorf("%d: prev: expected %q, got %q", i, test.expBW, prev)
		}
	}
}

// TestSendRPCRetry verifies that sendRPC failed on first address but succeed on
// second address, the second reply should be successfully returned back.
func TestSendRPCRetry(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	g.SetNodeID(1)
	if err := g.SetNodeDescriptor(&roachpb.NodeDescriptor{NodeID: 1}); err != nil {
		t.Fatal(err)
	}
	// Fill RangeDescriptor with 2 replicas
	var descriptor = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKey("z"),
	}
	for i := 1; i <= 2; i++ {
		addr := util.MakeUnresolvedAddr("tcp", fmt.Sprintf("node%d", i))
		nd := &roachpb.NodeDescriptor{
			NodeID:  roachpb.NodeID(i),
			Address: util.MakeUnresolvedAddr(addr.Network(), addr.String()),
		}
		if err := g.AddInfoProto(gossip.MakeNodeIDKey(roachpb.NodeID(i)), nd, time.Hour); err != nil {
			t.Fatal(err)
		}

		descriptor.Replicas = append(descriptor.Replicas, roachpb.ReplicaDescriptor{
			NodeID:  roachpb.NodeID(i),
			StoreID: roachpb.StoreID(i),
		})
	}
	var testFn rpcSendFn = func(_ SendOptions, _ ReplicaSlice,
		args roachpb.BatchRequest, _ *rpc.Context) (proto.Message, error) {
		batchReply := &roachpb.BatchResponse{}
		reply := &roachpb.ScanResponse{}
		batchReply.Add(reply)
		reply.Rows = append([]roachpb.KeyValue{}, roachpb.KeyValue{Key: roachpb.Key("b"), Value: roachpb.Value{}})
		return batchReply, nil
	}
	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(_ roachpb.RKey, _, _ bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			return []roachpb.RangeDescriptor{descriptor}, nil
		}),
	}
	ds := NewDistSender(ctx, g)
	scan := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("d"), 1)
	sr, err := client.SendWrapped(ds, nil, scan)
	if err != nil {
		t.Fatal(err)
	}
	if l := len(sr.(*roachpb.ScanResponse).Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
}