Golang roachpb.NewScan函數代碼示例

// TestMultiRangeScanWithMaxResults tests that commands which access multiple
// ranges with MaxResults parameter are carried out properly.
func TestMultiRangeScanWithMaxResults(t *testing.T) {
	defer leaktest.AfterTest(t)()
	testCases := []struct {
		splitKeys []roachpb.Key
		keys      []roachpb.Key
	}{
		{[]roachpb.Key{roachpb.Key("m")},
			[]roachpb.Key{roachpb.Key("a"), roachpb.Key("z")}},
		{[]roachpb.Key{roachpb.Key("h"), roachpb.Key("q")},
			[]roachpb.Key{roachpb.Key("b"), roachpb.Key("f"), roachpb.Key("k"),
				roachpb.Key("r"), roachpb.Key("w"), roachpb.Key("y")}},
	}

	for i, tc := range testCases {
		s, _, _ := serverutils.StartServer(t, base.TestServerArgs{})
		defer s.Stopper().Stop()
		ts := s.(*TestServer)
		retryOpts := base.DefaultRetryOptions()
		retryOpts.Closer = ts.stopper.ShouldDrain()
		ds := kv.NewDistSender(&kv.DistSenderContext{
			Clock:           s.Clock(),
			RPCContext:      s.RPCContext(),
			RPCRetryOptions: &retryOpts,
		}, ts.Gossip())
		tds := kv.NewTxnCoordSender(ds, ts.Clock(), ts.Ctx.Linearizable, tracing.NewTracer(),
			ts.stopper, kv.NewTxnMetrics(metric.NewRegistry()))

		for _, sk := range tc.splitKeys {
			if err := ts.node.ctx.DB.AdminSplit(sk); err != nil {
				t.Fatal(err)
			}
		}

		for _, k := range tc.keys {
			put := roachpb.NewPut(k, roachpb.MakeValueFromBytes(k))
			if _, err := client.SendWrapped(tds, nil, put); err != nil {
				t.Fatal(err)
			}
		}

		// Try every possible ScanRequest startKey.
		for start := 0; start < len(tc.keys); start++ {
			// Try every possible maxResults, from 1 to beyond the size of key array.
			for maxResults := 1; maxResults <= len(tc.keys)-start+1; maxResults++ {
				scan := roachpb.NewScan(tc.keys[start], tc.keys[len(tc.keys)-1].Next(),
					int64(maxResults))
				reply, err := client.SendWrapped(tds, nil, scan)
				if err != nil {
					t.Fatal(err)
				}
				rows := reply.(*roachpb.ScanResponse).Rows
				if start+maxResults <= len(tc.keys) && len(rows) != maxResults {
					t.Errorf("%d: start=%s: expected %d rows, but got %d", i, tc.keys[start], maxResults, len(rows))
				} else if start+maxResults == len(tc.keys)+1 && len(rows) != maxResults-1 {
					t.Errorf("%d: expected %d rows, but got %d", i, maxResults-1, len(rows))
				}
			}
		}
	}
}

// TestMultiRangeScanReverseScanInconsistent verifies that a Scan/ReverseScan
// across ranges that doesn't require read consistency will set a timestamp
// using the clock local to the distributed sender.
func TestMultiRangeScanReverseScanInconsistent(t *testing.T) {
	defer leaktest.AfterTest(t)
	s, db := setupMultipleRanges(t, "b")
	defer s.Stop()

	// Write keys "a" and "b", the latter of which is the first key in the
	// second range.
	keys := []string{"a", "b"}
	ts := []time.Time{}
	for i, key := range keys {
		b := &client.Batch{}
		b.Put(key, "value")
		if err := db.Run(b); err != nil {
			t.Fatal(err)
		}
		ts = append(ts, b.Results[0].Rows[0].Timestamp())
		log.Infof("%d: %s", i, b.Results[0].Rows[0].Timestamp())
	}

	// Do an inconsistent Scan/ReverseScan from a new DistSender and verify
	// it does the read at its local clock and doesn't receive an
	// OpRequiresTxnError. We set the local clock to the timestamp of
	// the first key to verify it's used to read only key "a".
	manual := hlc.NewManualClock(ts[1].UnixNano() - 1)
	clock := hlc.NewClock(manual.UnixNano)
	ds := kv.NewDistSender(&kv.DistSenderContext{Clock: clock}, s.Gossip())

	// Scan.
	sa := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("c"), 0).(*roachpb.ScanRequest)
	reply, err := client.SendWrappedWith(ds, nil, roachpb.BatchRequest_Header{
		ReadConsistency: roachpb.INCONSISTENT,
	}, sa)
	if err != nil {
		t.Fatal(err)
	}
	sr := reply.(*roachpb.ScanResponse)

	if l := len(sr.Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
	if key := string(sr.Rows[0].Key); keys[0] != key {
		t.Errorf("expected key %q; got %q", keys[0], key)
	}

	// ReverseScan.
	rsa := roachpb.NewReverseScan(roachpb.Key("a"), roachpb.Key("c"), 0).(*roachpb.ReverseScanRequest)
	reply, err = client.SendWrappedWith(ds, nil, roachpb.BatchRequest_Header{
		ReadConsistency: roachpb.INCONSISTENT,
	}, rsa)
	if err != nil {
		t.Fatal(err)
	}
	rsr := reply.(*roachpb.ReverseScanResponse)
	if l := len(rsr.Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
	if key := string(rsr.Rows[0].Key); keys[0] != key {
		t.Errorf("expected key %q; got %q", keys[0], key)
	}
}

// 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)
	}
}

// TestRetryOnWrongReplicaError sets up a DistSender on a minimal gossip
// network and a mock of rpc.Send, and verifies that the DistSender correctly
// retries upon encountering a stale entry in its range descriptor cache.
func TestRetryOnWrongReplicaError(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	// Updated below, after it has first been returned.
	badStartKey := roachpb.RKey("m")
	newRangeDescriptor := testRangeDescriptor
	goodStartKey := newRangeDescriptor.StartKey
	newRangeDescriptor.StartKey = badStartKey
	descStale := true

	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) {
		ba := getArgs(testAddress).(*roachpb.BatchRequest)
		rs := keys.Range(*ba)
		if _, ok := ba.GetArg(roachpb.RangeLookup); ok {
			if !descStale && bytes.HasPrefix(rs.Key, keys.Meta2Prefix) {
				t.Errorf("unexpected extra lookup for non-stale replica descriptor at %s",
					rs.Key)
			}

			br := getReply().(*roachpb.BatchResponse)
			r := &roachpb.RangeLookupResponse{}
			r.Ranges = append(r.Ranges, newRangeDescriptor)
			br.Add(r)
			// If we just returned the stale descriptor, set up returning the
			// good one next time.
			if bytes.HasPrefix(rs.Key, keys.Meta2Prefix) {
				if newRangeDescriptor.StartKey.Equal(badStartKey) {
					newRangeDescriptor.StartKey = goodStartKey
				} else {
					descStale = false
				}
			}
			return []proto.Message{br}, nil
		}
		// When the Scan first turns up, update the descriptor for future
		// range descriptor lookups.
		if !newRangeDescriptor.StartKey.Equal(goodStartKey) {
			return nil, &roachpb.RangeKeyMismatchError{RequestStartKey: rs.Key.AsRawKey(),
				RequestEndKey: rs.EndKey.AsRawKey()}
		}
		return []proto.Message{ba.CreateReply()}, nil
	}

	ctx := &DistSenderContext{
		RPCSend: testFn,
	}
	ds := NewDistSender(ctx, g)
	scan := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("d"), 0)
	if _, err := client.SendWrapped(ds, nil, scan); err != nil {
		t.Errorf("scan encountered error: %s", err)
	}
}

// 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)
	}
}

// TestMultiRangeScanWithMaxResults tests that commands which access multiple
// ranges with MaxResults parameter are carried out properly.
func TestMultiRangeScanWithMaxResults(t *testing.T) {
	defer leaktest.AfterTest(t)
	testCases := []struct {
		splitKeys []roachpb.Key
		keys      []roachpb.Key
	}{
		{[]roachpb.Key{roachpb.Key("m")},
			[]roachpb.Key{roachpb.Key("a"), roachpb.Key("z")}},
		{[]roachpb.Key{roachpb.Key("h"), roachpb.Key("q")},
			[]roachpb.Key{roachpb.Key("b"), roachpb.Key("f"), roachpb.Key("k"),
				roachpb.Key("r"), roachpb.Key("w"), roachpb.Key("y")}},
	}

	for i, tc := range testCases {
		s := StartTestServer(t)
		ds := kv.NewDistSender(&kv.DistSenderContext{Clock: s.Clock()}, s.Gossip())
		tds := kv.NewTxnCoordSender(ds, s.Clock(), testContext.Linearizable, nil, s.stopper)

		for _, sk := range tc.splitKeys {
			if err := s.node.ctx.DB.AdminSplit(sk); err != nil {
				t.Fatal(err)
			}
		}

		for _, k := range tc.keys {
			put := roachpb.NewPut(k, roachpb.Value{Bytes: k})
			if _, err := client.SendWrapped(tds, nil, put); err != nil {
				t.Fatal(err)
			}
		}

		// Try every possible ScanRequest startKey.
		for start := 0; start < len(tc.keys); start++ {
			// Try every possible maxResults, from 1 to beyond the size of key array.
			for maxResults := 1; maxResults <= len(tc.keys)-start+1; maxResults++ {
				scan := roachpb.NewScan(tc.keys[start], tc.keys[len(tc.keys)-1].Next(),
					int64(maxResults))
				reply, err := client.SendWrapped(tds, nil, scan)
				if err != nil {
					t.Fatal(err)
				}
				rows := reply.(*roachpb.ScanResponse).Rows
				if start+maxResults <= len(tc.keys) && len(rows) != maxResults {
					t.Errorf("%d: start=%s: expected %d rows, but got %d", i, tc.keys[start], maxResults, len(rows))
				} else if start+maxResults == len(tc.keys)+1 && len(rows) != maxResults-1 {
					t.Errorf("%d: expected %d rows, but got %d", i, maxResults-1, len(rows))
				}
			}
		}
		defer s.Stop()
	}
}

func (b *Batch) scan(s, e interface{}, maxRows int64, isReverse bool) {
	begin, err := marshalKey(s)
	if err != nil {
		b.initResult(0, 0, err)
		return
	}
	end, err := marshalKey(e)
	if err != nil {
		b.initResult(0, 0, err)
		return
	}
	if !isReverse {
		b.reqs = append(b.reqs, roachpb.NewScan(roachpb.Key(begin), roachpb.Key(end), maxRows))
	} else {
		b.reqs = append(b.reqs, roachpb.NewReverseScan(roachpb.Key(begin), roachpb.Key(end), maxRows))
	}
	b.initResult(1, 0, nil)
}

func (b *Batch) scan(s, e interface{}, isReverse bool) {
	begin, err := marshalKey(s)
	if err != nil {
		b.initResult(0, 0, notRaw, err)
		return
	}
	end, err := marshalKey(e)
	if err != nil {
		b.initResult(0, 0, notRaw, err)
		return
	}
	if !isReverse {
		b.appendReqs(roachpb.NewScan(begin, end))
	} else {
		b.appendReqs(roachpb.NewReverseScan(begin, end))
	}
	b.initResult(1, 0, notRaw, nil)
}

// TestMultiRangeMergeStaleDescriptor simulates the situation in which the
// DistSender executes a multi-range scan which encounters the stale descriptor
// of a range which has since incorporated its right neighbor by means of a
// merge. It is verified that the DistSender scans the correct keyrange exactly
// once.
func TestMultiRangeMergeStaleDescriptor(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	// Assume we have two ranges, [a-b) and [b-KeyMax).
	merged := false
	// The stale first range descriptor which is unaware of the merge.
	var FirstRange = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKey("b"),
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}
	// The merged descriptor, which will be looked up after having processed
	// the stale range [a,b).
	var mergedRange = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKeyMax,
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}
	// Assume we have two key-value pairs, a=1 and c=2.
	existingKVs := []roachpb.KeyValue{
		{Key: roachpb.Key("a"), Value: roachpb.MakeValueFromString("1")},
		{Key: roachpb.Key("c"), Value: roachpb.MakeValueFromString("2")},
	}
	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" {
			t.Fatalf("unexpected method:%s", method)
		}
		ba := getArgs(testAddress).(*roachpb.BatchRequest)
		rs := keys.Range(*ba)
		batchReply := getReply().(*roachpb.BatchResponse)
		reply := &roachpb.ScanResponse{}
		batchReply.Add(reply)
		results := []roachpb.KeyValue{}
		for _, curKV := range existingKVs {
			if rs.Key.Less(keys.Addr(curKV.Key).Next()) && keys.Addr(curKV.Key).Less(rs.EndKey) {
				results = append(results, curKV)
			}
		}
		reply.Rows = results
		return []proto.Message{batchReply}, nil
	}
	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(key roachpb.RKey, _, _ bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			if !merged {
				// Assume a range merge operation happened.
				merged = true
				return []roachpb.RangeDescriptor{FirstRange}, nil
			}
			return []roachpb.RangeDescriptor{mergedRange}, nil
		}),
	}
	ds := NewDistSender(ctx, g)
	scan := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("d"), 10).(*roachpb.ScanRequest)
	// Set the Txn info to avoid an OpRequiresTxnError.
	reply, err := client.SendWrappedWith(ds, nil, roachpb.Header{
		Txn: &roachpb.Transaction{},
	}, scan)
	if err != nil {
		t.Fatalf("scan encountered error: %s", err)
	}
	sr := reply.(*roachpb.ScanResponse)
	if !reflect.DeepEqual(existingKVs, sr.Rows) {
		t.Fatalf("expect get %v, actual get %v", existingKVs, sr.Rows)
	}
}

// TestMultiRangeScanDeleteRange tests that commands which access multiple
// ranges are carried out properly.
func TestMultiRangeScanDeleteRange(t *testing.T) {
	defer leaktest.AfterTest(t)
	s := StartTestServer(t)
	defer s.Stop()
	ds := kv.NewDistSender(&kv.DistSenderContext{Clock: s.Clock()}, s.Gossip())
	tds := kv.NewTxnCoordSender(ds, s.Clock(), testContext.Linearizable, nil, s.stopper)

	if err := s.node.ctx.DB.AdminSplit("m"); err != nil {
		t.Fatal(err)
	}
	writes := []roachpb.Key{roachpb.Key("a"), roachpb.Key("z")}
	get := &roachpb.GetRequest{
		Span: roachpb.Span{Key: writes[0]},
	}
	get.EndKey = writes[len(writes)-1]
	if _, err := client.SendWrapped(tds, nil, get); err == nil {
		t.Errorf("able to call Get with a key range: %v", get)
	}
	var delTS roachpb.Timestamp
	for i, k := range writes {
		put := roachpb.NewPut(k, roachpb.MakeValueFromBytes(k))
		reply, err := client.SendWrapped(tds, nil, put)
		if err != nil {
			t.Fatal(err)
		}
		scan := roachpb.NewScan(writes[0], writes[len(writes)-1].Next(), 0).(*roachpb.ScanRequest)
		// The Put ts may have been pushed by tsCache,
		// so make sure we see their values in our Scan.
		delTS = reply.(*roachpb.PutResponse).Timestamp
		reply, err = client.SendWrappedWith(tds, nil, roachpb.Header{Timestamp: delTS}, scan)
		if err != nil {
			t.Fatal(err)
		}
		sr := reply.(*roachpb.ScanResponse)
		if sr.Txn != nil {
			// This was the other way around at some point in the past.
			// Same below for Delete, etc.
			t.Errorf("expected no transaction in response header")
		}
		if rows := sr.Rows; len(rows) != i+1 {
			t.Fatalf("expected %d rows, but got %d", i+1, len(rows))
		}
	}

	del := &roachpb.DeleteRangeRequest{
		Span: roachpb.Span{
			Key:    writes[0],
			EndKey: roachpb.Key(writes[len(writes)-1]).Next(),
		},
	}
	reply, err := client.SendWrappedWith(tds, nil, roachpb.Header{Timestamp: delTS}, del)
	if err != nil {
		t.Fatal(err)
	}
	dr := reply.(*roachpb.DeleteRangeResponse)
	if dr.Txn != nil {
		t.Errorf("expected no transaction in response header")
	}
	if n := dr.NumDeleted; n != int64(len(writes)) {
		t.Errorf("expected %d keys to be deleted, but got %d instead",
			len(writes), n)
	}

	scan := roachpb.NewScan(writes[0], writes[len(writes)-1].Next(), 0).(*roachpb.ScanRequest)
	txn := &roachpb.Transaction{Name: "MyTxn"}
	reply, err = client.SendWrappedWith(tds, nil, roachpb.Header{Txn: txn}, scan)
	if err != nil {
		t.Fatal(err)
	}
	sr := reply.(*roachpb.ScanResponse)
	if txn := sr.Txn; txn == nil || txn.Name != "MyTxn" {
		t.Errorf("wanted Txn to persist, but it changed to %v", txn)
	}
	if rows := sr.Rows; len(rows) > 0 {
		t.Fatalf("scan after delete returned rows: %v", rows)
	}
}

// TestMultiRangeScanReverseScanInconsistent verifies that a Scan/ReverseScan
// across ranges that doesn't require read consistency will set a timestamp
// using the clock local to the distributed sender.
func TestMultiRangeScanReverseScanInconsistent(t *testing.T) {
	defer leaktest.AfterTest(t)

	s := server.StartTestServer(t)
	defer s.Stop()
	db := setupMultipleRanges(t, s, "b")

	// Write keys "a" and "b", the latter of which is the first key in the
	// second range.
	keys := [2]string{"a", "b"}
	ts := [2]time.Time{}
	for i, key := range keys {
		b := &client.Batch{}
		b.Put(key, "value")
		if pErr := db.Run(b); pErr != nil {
			t.Fatal(pErr)
		}
		ts[i] = b.Results[0].Rows[0].Timestamp()
		log.Infof("%d: %d.%d", i, ts[i].Unix(), ts[i].Nanosecond())
		if i == 0 {
			util.SucceedsWithin(t, time.Second, func() error {
				// Enforce that when we write the second key, it's written
				// with a strictly higher timestamp. We're dropping logical
				// ticks and the clock may just have been pushed into the
				// future, so that's necessary. See #3122.
				if !s.Clock().PhysicalTime().After(ts[0]) {
					return errors.New("time stands still")
				}
				return nil
			})
		}
	}

	// Do an inconsistent Scan/ReverseScan from a new DistSender and verify
	// it does the read at its local clock and doesn't receive an
	// OpRequiresTxnError. We set the local clock to the timestamp of
	// the first key to verify it's used to read only key "a".
	manual := hlc.NewManualClock(ts[1].UnixNano() - 1)
	clock := hlc.NewClock(manual.UnixNano)
	ds := kv.NewDistSender(&kv.DistSenderContext{Clock: clock, RPCContext: s.RPCContext()}, s.Gossip())

	// Scan.
	sa := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("c"), 0).(*roachpb.ScanRequest)
	reply, pErr := client.SendWrappedWith(ds, nil, roachpb.Header{
		ReadConsistency: roachpb.INCONSISTENT,
	}, sa)
	if pErr != nil {
		t.Fatal(pErr)
	}
	sr := reply.(*roachpb.ScanResponse)

	if l := len(sr.Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
	if key := string(sr.Rows[0].Key); keys[0] != key {
		t.Errorf("expected key %q; got %q", keys[0], key)
	}

	// ReverseScan.
	rsa := roachpb.NewReverseScan(roachpb.Key("a"), roachpb.Key("c"), 0).(*roachpb.ReverseScanRequest)
	reply, pErr = client.SendWrappedWith(ds, nil, roachpb.Header{
		ReadConsistency: roachpb.INCONSISTENT,
	}, rsa)
	if pErr != nil {
		t.Fatal(pErr)
	}
	rsr := reply.(*roachpb.ReverseScanResponse)
	if l := len(rsr.Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
	if key := string(rsr.Rows[0].Key); keys[0] != key {
		t.Errorf("expected key %q; got %q", keys[0], key)
	}
}

// TestMultiRangeScanReverseScanInconsistent verifies that a Scan/ReverseScan
// across ranges that doesn't require read consistency will set a timestamp
// using the clock local to the distributed sender.
func TestMultiRangeScanReverseScanInconsistent(t *testing.T) {
	defer leaktest.AfterTest(t)
	s, db := setupMultipleRanges(t, "b")
	defer s.Stop()

	// Write keys "a" and "b", the latter of which is the first key in the
	// second range.
	keys := [2]string{"a", "b"}
	ts := [2]time.Time{}
	// This outer loop may seem awkward, but we've actually had issue #3122
	// since the two timestamps ended up equal. This can happen (very rarely)
	// since both timestamps are HLC internally and then have their logical
	// component dropped. Lease changes can push the HLC ahead of the wall
	// time for short amounts of time, so that losing the logical tick matters.
	for !ts[1].After(ts[0]) {
		for i, key := range keys {
			b := &client.Batch{}
			b.Put(key, "value")
			if err := db.Run(b); err != nil {
				t.Fatal(err)
			}
			ts[i] = b.Results[0].Rows[0].Timestamp()
			log.Infof("%d: %s", i, b.Results[0].Rows[0].Timestamp())
		}
	}

	// Do an inconsistent Scan/ReverseScan from a new DistSender and verify
	// it does the read at its local clock and doesn't receive an
	// OpRequiresTxnError. We set the local clock to the timestamp of
	// the first key to verify it's used to read only key "a".
	manual := hlc.NewManualClock(ts[1].UnixNano() - 1)
	clock := hlc.NewClock(manual.UnixNano)
	ds := kv.NewDistSender(&kv.DistSenderContext{Clock: clock}, s.Gossip())

	// Scan.
	sa := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("c"), 0).(*roachpb.ScanRequest)
	reply, err := client.SendWrappedWith(ds, nil, roachpb.Header{
		ReadConsistency: roachpb.INCONSISTENT,
	}, sa)
	if err != nil {
		t.Fatal(err)
	}
	sr := reply.(*roachpb.ScanResponse)

	if l := len(sr.Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
	if key := string(sr.Rows[0].Key); keys[0] != key {
		t.Errorf("expected key %q; got %q", keys[0], key)
	}

	// ReverseScan.
	rsa := roachpb.NewReverseScan(roachpb.Key("a"), roachpb.Key("c"), 0).(*roachpb.ReverseScanRequest)
	reply, err = client.SendWrappedWith(ds, nil, roachpb.Header{
		ReadConsistency: roachpb.INCONSISTENT,
	}, rsa)
	if err != nil {
		t.Fatal(err)
	}
	rsr := reply.(*roachpb.ReverseScanResponse)
	if l := len(rsr.Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
	if key := string(rsr.Rows[0].Key); keys[0] != key {
		t.Errorf("expected key %q; got %q", keys[0], key)
	}
}

// TestMultiRangeScanDeleteRange tests that commands which access multiple
// ranges are carried out properly.
func TestMultiRangeScanDeleteRange(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, _, _ := serverutils.StartServer(t, base.TestServerArgs{})
	defer s.Stopper().Stop()
	ts := s.(*TestServer)
	retryOpts := base.DefaultRetryOptions()
	retryOpts.Closer = ts.stopper.ShouldQuiesce()
	ds := kv.NewDistSender(&kv.DistSenderConfig{
		Clock:           s.Clock(),
		RPCContext:      s.RPCContext(),
		RPCRetryOptions: &retryOpts,
	}, ts.Gossip())
	ctx := tracing.WithTracer(context.Background(), tracing.NewTracer())
	tds := kv.NewTxnCoordSender(ctx, ds, s.Clock(), ts.Ctx.Linearizable,
		ts.stopper, kv.MakeTxnMetrics())

	if err := ts.node.ctx.DB.AdminSplit("m"); err != nil {
		t.Fatal(err)
	}
	writes := []roachpb.Key{roachpb.Key("a"), roachpb.Key("z")}
	get := &roachpb.GetRequest{
		Span: roachpb.Span{Key: writes[0]},
	}
	get.EndKey = writes[len(writes)-1]
	if _, err := client.SendWrapped(tds, nil, get); err == nil {
		t.Errorf("able to call Get with a key range: %v", get)
	}
	var delTS hlc.Timestamp
	for i, k := range writes {
		put := roachpb.NewPut(k, roachpb.MakeValueFromBytes(k))
		reply, err := client.SendWrapped(tds, nil, put)
		if err != nil {
			t.Fatal(err)
		}
		scan := roachpb.NewScan(writes[0], writes[len(writes)-1].Next())
		reply, err = client.SendWrapped(tds, nil, scan)
		if err != nil {
			t.Fatal(err)
		}
		sr := reply.(*roachpb.ScanResponse)
		if sr.Txn != nil {
			// This was the other way around at some point in the past.
			// Same below for Delete, etc.
			t.Errorf("expected no transaction in response header")
		}
		if rows := sr.Rows; len(rows) != i+1 {
			t.Fatalf("expected %d rows, but got %d", i+1, len(rows))
		}
	}

	del := &roachpb.DeleteRangeRequest{
		Span: roachpb.Span{
			Key:    writes[0],
			EndKey: roachpb.Key(writes[len(writes)-1]).Next(),
		},
		ReturnKeys: true,
	}
	reply, err := client.SendWrappedWith(tds, nil, roachpb.Header{Timestamp: delTS}, del)
	if err != nil {
		t.Fatal(err)
	}
	dr := reply.(*roachpb.DeleteRangeResponse)
	if dr.Txn != nil {
		t.Errorf("expected no transaction in response header")
	}
	if !reflect.DeepEqual(dr.Keys, writes) {
		t.Errorf("expected %d keys to be deleted, but got %d instead", writes, dr.Keys)
	}

	scan := roachpb.NewScan(writes[0], writes[len(writes)-1].Next())
	txn := &roachpb.Transaction{Name: "MyTxn"}
	reply, err = client.SendWrappedWith(tds, nil, roachpb.Header{Txn: txn}, scan)
	if err != nil {
		t.Fatal(err)
	}
	sr := reply.(*roachpb.ScanResponse)
	if txn := sr.Txn; txn == nil || txn.Name != "MyTxn" {
		t.Errorf("wanted Txn to persist, but it changed to %v", txn)
	}
	if rows := sr.Rows; len(rows) > 0 {
		t.Fatalf("scan after delete returned rows: %v", rows)
	}
}

// TestMultiRangeScanReverseScanInconsistent verifies that a Scan/ReverseScan
// across ranges that doesn't require read consistency will set a timestamp
// using the clock local to the distributed sender.
func TestMultiRangeScanReverseScanInconsistent(t *testing.T) {
	defer leaktest.AfterTest(t)()

	s := server.StartTestServer(t)
	defer s.Stop()
	db := setupMultipleRanges(t, s, "b")

	// Write keys "a" and "b", the latter of which is the first key in the
	// second range.
	keys := [2]string{"a", "b"}
	ts := [2]roachpb.Timestamp{}
	for i, key := range keys {
		b := &client.Batch{}
		b.Put(key, "value")
		if err := db.Run(b); err != nil {
			t.Fatal(err)
		}
		ts[i] = s.Clock().Now()
		log.Infof("%d: %d", i, ts[i])
		if i == 0 {
			util.SucceedsSoon(t, func() error {
				// Enforce that when we write the second key, it's written
				// with a strictly higher timestamp. We're dropping logical
				// ticks and the clock may just have been pushed into the
				// future, so that's necessary. See #3122.
				if !ts[0].Less(s.Clock().Now()) {
					return errors.New("time stands still")
				}
				return nil
			})
		}
	}

	// Do an inconsistent Scan/ReverseScan from a new DistSender and verify
	// it does the read at its local clock and doesn't receive an
	// OpRequiresTxnError. We set the local clock to the timestamp of
	// just above the first key to verify it's used to read only key "a".
	for _, request := range []roachpb.Request{
		roachpb.NewScan(roachpb.Key("a"), roachpb.Key("c"), 0),
		roachpb.NewReverseScan(roachpb.Key("a"), roachpb.Key("c"), 0),
	} {
		manual := hlc.NewManualClock(ts[0].WallTime + 1)
		clock := hlc.NewClock(manual.UnixNano)
		ds := kv.NewDistSender(&kv.DistSenderContext{Clock: clock, RPCContext: s.RPCContext()}, s.Gossip())

		reply, err := client.SendWrappedWith(ds, nil, roachpb.Header{
			ReadConsistency: roachpb.INCONSISTENT,
		}, request)
		if err != nil {
			t.Fatal(err)
		}

		var rows []roachpb.KeyValue
		switch r := reply.(type) {
		case *roachpb.ScanResponse:
			rows = r.Rows
		case *roachpb.ReverseScanResponse:
			rows = r.Rows
		default:
			t.Fatalf("unexpected response %T: %v", reply, reply)
		}

		if l := len(rows); l != 1 {
			t.Fatalf("expected 1 row; got %d", l)
		}
		if key := string(rows[0].Key); keys[0] != key {
			t.Errorf("expected key %q; got %q", keys[0], key)
		}
	}
}

//.........這裏部分代碼省略.........
		EndKey:   roachpb.RKey("b"),
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}
	var descriptor2 = roachpb.RangeDescriptor{
		RangeID:  2,
		StartKey: roachpb.RKey("b"),
		EndKey:   roachpb.RKey("c"),
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}
	var descriptor3 = roachpb.RangeDescriptor{
		RangeID:  3,
		StartKey: roachpb.RKey("c"),
		EndKey:   roachpb.RKeyMax,
		Replicas: []roachpb.ReplicaDescriptor{
			{
				NodeID:  1,
				StoreID: 1,
			},
		},
	}

	descDB := mockRangeDescriptorDB(func(key roachpb.RKey, _, _ bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
		switch {
		case !key.Less(roachpb.RKey("c")):
			return []roachpb.RangeDescriptor{descriptor3}, nil
		case !key.Less(roachpb.RKey("b")):
			return []roachpb.RangeDescriptor{descriptor2}, nil
		default:
			return []roachpb.RangeDescriptor{descriptor1}, nil
		}
	})

	// Define our rpcSend stub which checks the span of the batch
	// requests.
	requests := 0
	sendStub := func(_ SendOptions, _ ReplicaSlice, ba roachpb.BatchRequest, _ *rpc.Context) (*roachpb.BatchResponse, error) {
		h := ba.Requests[0].GetInner().Header()
		switch requests {
		case 0:
			wantStart := keys.RangeDescriptorKey(roachpb.RKey("a"))
			wantEnd := keys.MakeRangeKeyPrefix(roachpb.RKey("b"))
			if !(h.Key.Equal(wantStart) && h.EndKey.Equal(wantEnd)) {
				t.Errorf("Unexpected span [%s,%s), want [%s,%s)", h.Key, h.EndKey, wantStart, wantEnd)
			}
		case 1:
			wantStart := keys.MakeRangeKeyPrefix(roachpb.RKey("b"))
			wantEnd := keys.MakeRangeKeyPrefix(roachpb.RKey("c"))
			if !(h.Key.Equal(wantStart) && h.EndKey.Equal(wantEnd)) {
				t.Errorf("Unexpected span [%s,%s), want [%s,%s)", h.Key, h.EndKey, wantStart, wantEnd)
			}
		case 2:
			wantStart := keys.MakeRangeKeyPrefix(roachpb.RKey("c"))
			wantEnd := keys.RangeDescriptorKey(roachpb.RKey("c"))
			if !(h.Key.Equal(wantStart) && h.EndKey.Equal(wantEnd)) {
				t.Errorf("Unexpected span [%s,%s), want [%s,%s)", h.Key, h.EndKey, wantStart, wantEnd)
			}
		}
		requests++

		batchReply := &roachpb.BatchResponse{}
		reply := &roachpb.ScanResponse{}
		batchReply.Add(reply)
		return batchReply, nil
	}

	ctx := &DistSenderContext{
		RPCSend:           sendStub,
		RangeDescriptorDB: descDB,
	}
	ds := NewDistSender(ctx, g)

	// Send a batch request contains two scans. In the first
	// attempt, the range of the descriptor found in the cache is
	// ["", "b"). The request is truncated to contain only the scan
	// on local keys that address up to "b".
	//
	// In the second attempt, The range of the descriptor found in
	// the cache is ["b", "d"), The request is truncated to contain
	// only the scan on local keys that address from "b" to "d".
	ba := roachpb.BatchRequest{}
	ba.Txn = &roachpb.Transaction{Name: "test"}
	ba.Add(roachpb.NewScan(keys.RangeDescriptorKey(roachpb.RKey("a")), keys.RangeDescriptorKey(roachpb.RKey("c")), 0))

	if _, pErr := ds.Send(context.Background(), ba); pErr != nil {
		t.Fatal(pErr)
	}
	if want := 3; requests != want {
		t.Errorf("expected request to be split into %d parts, found %d", want, requests)
	}
}