// recordJoinEvent begins an asynchronous task which attempts to log a "node
// join" or "node restart" event. This query will retry until it succeeds or the
// server stops.
func (n *Node) recordJoinEvent() {
	if !n.ctx.LogRangeEvents {
		return
	}

	logEventType := sql.EventLogNodeRestart
	if n.initialBoot {
		logEventType = sql.EventLogNodeJoin
	}

	n.stopper.RunWorker(func() {
		retryOpts := base.DefaultRetryOptions()
		retryOpts.Closer = n.stopper.ShouldStop()
		for r := retry.Start(retryOpts); r.Next(); {
			if err := n.ctx.DB.Txn(func(txn *client.Txn) error {
				return n.eventLogger.InsertEventRecord(txn,
					logEventType,
					int32(n.Descriptor.NodeID),
					int32(n.Descriptor.NodeID),
					struct {
						Descriptor roachpb.NodeDescriptor
						ClusterID  uuid.UUID
						StartedAt  int64
					}{n.Descriptor, n.ClusterID, n.startedAt},
				)
			}); err != nil {
				log.Warningc(n.context(context.TODO()), "unable to log %s event for node %d: %s", logEventType, n.Descriptor.NodeID, err)
			} else {
				return
			}
		}
	})
}

// 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))
				}
			}
		}
	}
}

// NewDistSender returns a batch.Sender instance which connects to the
// Cockroach cluster via the supplied gossip instance. Supplying a
// DistSenderContext or the fields within is optional. For omitted values, sane
// defaults will be used.
func NewDistSender(ctx *DistSenderContext, gossip *gossip.Gossip) *DistSender {
	if ctx == nil {
		ctx = &DistSenderContext{}
	}
	clock := ctx.Clock
	if clock == nil {
		clock = hlc.NewClock(hlc.UnixNano)
	}
	ds := &DistSender{
		clock:  clock,
		gossip: gossip,
	}
	if ctx.nodeDescriptor != nil {
		atomic.StorePointer(&ds.nodeDescriptor, unsafe.Pointer(ctx.nodeDescriptor))
	}
	rcSize := ctx.RangeDescriptorCacheSize
	if rcSize <= 0 {
		rcSize = defaultRangeDescriptorCacheSize
	}
	rdb := ctx.RangeDescriptorDB
	if rdb == nil {
		rdb = ds
	}
	ds.rangeCache = newRangeDescriptorCache(rdb, int(rcSize))
	lcSize := ctx.LeaderCacheSize
	if lcSize <= 0 {
		lcSize = defaultLeaderCacheSize
	}
	ds.leaderCache = newLeaderCache(int(lcSize))
	if ctx.RangeLookupMaxRanges <= 0 {
		ds.rangeLookupMaxRanges = defaultRangeLookupMaxRanges
	}
	if ctx.TransportFactory != nil {
		ds.transportFactory = ctx.TransportFactory
	}
	ds.rpcRetryOptions = base.DefaultRetryOptions()
	if ctx.RPCRetryOptions != nil {
		ds.rpcRetryOptions = *ctx.RPCRetryOptions
	}
	if ctx.RPCContext != nil {
		ds.rpcContext = ctx.RPCContext
		if ds.rpcRetryOptions.Closer == nil {
			ds.rpcRetryOptions.Closer = ds.rpcContext.Stopper.ShouldDrain()
		}
	}
	if ctx.Tracer != nil {
		ds.Tracer = ctx.Tracer
	} else {
		ds.Tracer = tracing.NewTracer()
	}
	if ctx.SendNextTimeout != 0 {
		ds.sendNextTimeout = ctx.SendNextTimeout
	} else {
		ds.sendNextTimeout = defaultSendNextTimeout
	}

	return ds
}

// createTestNode creates an rpc server using the specified address,
// gossip instance, KV database and a node using the specified slice
// of engines. The server, clock and node are returned. If gossipBS is
// not nil, the gossip bootstrap address is set to gossipBS.
func createTestNode(addr net.Addr, engines []engine.Engine, gossipBS net.Addr, t *testing.T) (
	*grpc.Server, net.Addr, *hlc.Clock, *Node, *stop.Stopper) {
	ctx := storage.StoreContext{}

	stopper := stop.NewStopper()
	ctx.Clock = hlc.NewClock(hlc.UnixNano)
	nodeRPCContext := rpc.NewContext(nodeTestBaseContext, ctx.Clock, stopper)
	ctx.ScanInterval = 10 * time.Hour
	ctx.ConsistencyCheckInterval = 10 * time.Hour
	grpcServer := rpc.NewServer(nodeRPCContext)
	serverCtx := makeTestContext()
	g := gossip.New(
		context.Background(),
		nodeRPCContext,
		grpcServer,
		serverCtx.GossipBootstrapResolvers,
		stopper,
		metric.NewRegistry())
	ln, err := netutil.ListenAndServeGRPC(stopper, grpcServer, addr)
	if err != nil {
		t.Fatal(err)
	}
	if gossipBS != nil {
		// Handle possibility of a :0 port specification.
		if gossipBS.Network() == addr.Network() && gossipBS.String() == addr.String() {
			gossipBS = ln.Addr()
		}
		r, err := resolver.NewResolverFromAddress(gossipBS)
		if err != nil {
			t.Fatalf("bad gossip address %s: %s", gossipBS, err)
		}
		g.SetResolvers([]resolver.Resolver{r})
		g.Start(ln.Addr())
	}
	ctx.Gossip = g
	retryOpts := base.DefaultRetryOptions()
	retryOpts.Closer = stopper.ShouldQuiesce()
	distSender := kv.NewDistSender(&kv.DistSenderConfig{
		Clock:           ctx.Clock,
		RPCContext:      nodeRPCContext,
		RPCRetryOptions: &retryOpts,
	}, g)
	ctx.Ctx = tracing.WithTracer(context.Background(), tracing.NewTracer())
	sender := kv.NewTxnCoordSender(ctx.Ctx, distSender, ctx.Clock, false, stopper,
		kv.MakeTxnMetrics())
	ctx.DB = client.NewDB(sender)
	ctx.Transport = storage.NewDummyRaftTransport()
	node := NewNode(ctx, status.NewMetricsRecorder(ctx.Clock), metric.NewRegistry(), stopper,
		kv.MakeTxnMetrics(), sql.MakeEventLogger(nil))
	roachpb.RegisterInternalServer(grpcServer, node)
	return grpcServer, ln.Addr(), ctx.Clock, node, stopper
}

// execSchemaChanges releases schema leases and runs the queued
// schema changers. This needs to be run after the transaction
// scheduling the schema change has finished.
//
// The list of closures is cleared after (attempting) execution.
//
// Args:
//  results: The results from all statements in the group that scheduled the
//    schema changes we're about to execute. Results corresponding to the
//    schema change statements will be changed in case an error occurs.
func (scc *schemaChangerCollection) execSchemaChanges(
	e *Executor, planMaker *planner, results ResultList,
) {
	if planMaker.txn != nil {
		panic("trying to execute schema changes while still in a transaction")
	}
	// Release the leases once a transaction is complete.
	planMaker.releaseLeases()
	if e.ctx.TestingKnobs.SyncSchemaChangersFilter != nil {
		e.ctx.TestingKnobs.SyncSchemaChangersFilter(TestingSchemaChangerCollection{scc})
	}
	// Execute any schema changes that were scheduled, in the order of the
	// statements that scheduled them.
	for _, scEntry := range scc.schemaChangers {
		sc := &scEntry.sc
		sc.db = *e.ctx.DB
		for r := retry.Start(base.DefaultRetryOptions()); r.Next(); {
			if done, err := sc.IsDone(); err != nil {
				log.Warning(e.ctx.Context, err)
				break
			} else if done {
				break
			}
			if err := sc.exec(
				e.ctx.TestingKnobs.SchemaChangersStartBackfillNotification,
				e.ctx.TestingKnobs.SyncSchemaChangersRenameOldNameNotInUseNotification,
			); err != nil {
				if isSchemaChangeRetryError(err) {
					// Try again
					continue
				}
				// All other errors can be reported; we report it as the result
				// corresponding to the statement that enqueued this changer.
				// There's some sketchiness here: we assume there's a single result
				// per statement and we clobber the result/error of the corresponding
				// statement.
				// There's also another subtlety: we can only report results for
				// statements in the current batch; we can't modify the results of older
				// statements.
				if scEntry.epoch == scc.curGroupNum {
					results[scEntry.idx] = Result{Err: err}
				}
				log.Warningf(e.ctx.Context, "Error executing schema change: %s", err)
			}
			break
		}
	}
	scc.schemaChangers = scc.schemaChangers[:0]
}

func (ia *idAllocator) start() {
	ia.stopper.RunWorker(func() {
		defer close(ia.ids)

		for {
			var newValue int64
			for newValue <= int64(ia.minID) {
				var (
					err error
					res client.KeyValue
				)
				for r := retry.Start(base.DefaultRetryOptions()); r.Next(); {
					idKey := ia.idKey.Load().(roachpb.Key)
					if !ia.stopper.RunTask(func() {
						res, err = ia.db.Inc(idKey, int64(ia.blockSize))
					}) {
						return
					}
					if err == nil {
						newValue = res.ValueInt()
						break
					}

					log.Warningf("unable to allocate %d ids from %s: %s", ia.blockSize, idKey, err)
				}
				if err != nil {
					panic(fmt.Sprintf("unexpectedly exited id allocation retry loop: %s", err))
				}
			}

			end := newValue + 1
			start := end - int64(ia.blockSize)

			if start < int64(ia.minID) {
				start = int64(ia.minID)
			}

			// Add all new ids to the channel for consumption.
			for i := start; i < end; i++ {
				select {
				case ia.ids <- uint32(i):
				case <-ia.stopper.ShouldStop():
					return
				}
			}
		}
	})
}

// InitSenderForLocalTestCluster initializes a TxnCoordSender that can be used
// with LocalTestCluster.
func InitSenderForLocalTestCluster(
	nodeDesc *roachpb.NodeDescriptor,
	tracer opentracing.Tracer,
	clock *hlc.Clock,
	latency time.Duration,
	stores client.Sender,
	stopper *stop.Stopper,
	gossip *gossip.Gossip,
) client.Sender {
	retryOpts := base.DefaultRetryOptions()
	retryOpts.Closer = stopper.ShouldQuiesce()
	senderTransportFactory := SenderTransportFactory(tracer, stores)
	distSender := NewDistSender(&DistSenderConfig{
		Clock: clock,
		RangeDescriptorCacheSize: defaultRangeDescriptorCacheSize,
		RangeLookupMaxRanges:     defaultRangeLookupMaxRanges,
		LeaseHolderCacheSize:     defaultLeaseHolderCacheSize,
		RPCRetryOptions:          &retryOpts,
		nodeDescriptor:           nodeDesc,
		TransportFactory: func(
			opts SendOptions,
			rpcContext *rpc.Context,
			replicas ReplicaSlice,
			args roachpb.BatchRequest,
		) (Transport, error) {
			transport, err := senderTransportFactory(opts, rpcContext, replicas, args)
			if err != nil {
				return nil, err
			}
			return &localTestClusterTransport{transport, latency}, nil
		},
		RangeDescriptorDB: stores.(RangeDescriptorDB), // for descriptor lookup
	}, gossip)

	ctx := tracing.WithTracer(context.Background(), tracer)
	return NewTxnCoordSender(ctx, distSender, clock, false, /* !linearizable */
		stopper, MakeTxnMetrics())
}

// Publish updates a table descriptor. It also maintains the invariant that
// there are at most two versions of the descriptor out in the wild at any time
// by first waiting for all nodes to be on the current (pre-update) version of
// the table desc.
// The update closure is called after the wait, and it provides the new version
// of the descriptor to be written. In a multi-step schema operation, this
// update should perform a single step.
// The closure may be called multiple times if retries occur; make sure it does
// not have side effects.
// Returns the updated version of the descriptor.
func (s LeaseStore) Publish(
	tableID sqlbase.ID,
	update func(*sqlbase.TableDescriptor) error,
	logEvent func(*client.Txn) error,
) (*sqlbase.Descriptor, error) {
	errLeaseVersionChanged := errors.New("lease version changed")
	// Retry while getting errLeaseVersionChanged.
	for r := retry.Start(base.DefaultRetryOptions()); r.Next(); {
		// Wait until there are no unexpired leases on the previous version
		// of the table.
		expectedVersion, err := s.waitForOneVersion(tableID, base.DefaultRetryOptions())
		if err != nil {
			return nil, err
		}

		desc := &sqlbase.Descriptor{}
		// There should be only one version of the descriptor, but it's
		// a race now to update to the next version.
		err = s.db.Txn(context.TODO(), func(txn *client.Txn) error {
			descKey := sqlbase.MakeDescMetadataKey(tableID)

			// Re-read the current version of the table descriptor, this time
			// transactionally.
			if err := txn.GetProto(descKey, desc); err != nil {
				return err
			}
			tableDesc := desc.GetTable()
			if tableDesc == nil {
				return errors.Errorf("ID %d is not a table", tableID)
			}
			if expectedVersion != tableDesc.Version {
				// The version changed out from under us. Someone else must be
				// performing a schema change operation.
				if log.V(3) {
					log.Infof(context.TODO(), "publish (version changed): %d != %d", expectedVersion, tableDesc.Version)
				}
				return errLeaseVersionChanged
			}

			// Run the update closure.
			if err := update(tableDesc); err != nil {
				return err
			}

			// Bump the version and modification time.
			tableDesc.Version++
			now := s.clock.Now()
			tableDesc.ModificationTime = now
			if log.V(3) {
				log.Infof(context.TODO(), "publish: descID=%d (%s) version=%d mtime=%s",
					tableDesc.ID, tableDesc.Name, tableDesc.Version, now.GoTime())
			}
			if err := tableDesc.ValidateTable(); err != nil {
				return err
			}

			// Write the updated descriptor.
			txn.SetSystemConfigTrigger()
			b := txn.NewBatch()
			b.Put(descKey, desc)
			if logEvent != nil {
				// If an event log is required for this update, ensure that the
				// descriptor change occurs first in the transaction. This is
				// necessary to ensure that the System configuration change is
				// gossiped. See the documentation for
				// transaction.SetSystemConfigTrigger() for more information.
				if err := txn.Run(b); err != nil {
					return err
				}
				if err := logEvent(txn); err != nil {
					return err
				}
				return txn.Commit()
			}
			// More efficient batching can be used if no event log message
			// is required.
			return txn.CommitInBatch(b)
		})

		switch err {
		case nil, errDidntUpdateDescriptor:
			return desc, nil
		case errLeaseVersionChanged:
			// will loop around to retry
		default:
			return nil, err
		}
	}

	panic("not reached")
//.........这里部分代码省略.........

// NewDistSender returns a batch.Sender instance which connects to the
// Cockroach cluster via the supplied gossip instance. Supplying a
// DistSenderContext or the fields within is optional. For omitted values, sane
// defaults will be used.
func NewDistSender(cfg *DistSenderConfig, g *gossip.Gossip) *DistSender {
	if cfg == nil {
		cfg = &DistSenderConfig{}
	}

	ds := &DistSender{gossip: g}

	ds.Ctx = cfg.Ctx
	if ds.Ctx == nil {
		ds.Ctx = context.Background()
	}

	if ds.Ctx.Done() != nil {
		panic("context with cancel or deadline")
	}

	if tracing.TracerFromCtx(ds.Ctx) == nil {
		ds.Ctx = tracing.WithTracer(ds.Ctx, tracing.NewTracer())
	}

	ds.clock = cfg.Clock
	if ds.clock == nil {
		ds.clock = hlc.NewClock(hlc.UnixNano)
	}

	if cfg.nodeDescriptor != nil {
		atomic.StorePointer(&ds.nodeDescriptor, unsafe.Pointer(cfg.nodeDescriptor))
	}
	rcSize := cfg.RangeDescriptorCacheSize
	if rcSize <= 0 {
		rcSize = defaultRangeDescriptorCacheSize
	}
	rdb := cfg.RangeDescriptorDB
	if rdb == nil {
		rdb = ds
	}
	ds.rangeCache = newRangeDescriptorCache(rdb, int(rcSize))
	lcSize := cfg.LeaseHolderCacheSize
	if lcSize <= 0 {
		lcSize = defaultLeaseHolderCacheSize
	}
	ds.leaseHolderCache = newLeaseHolderCache(int(lcSize))
	if cfg.RangeLookupMaxRanges <= 0 {
		ds.rangeLookupMaxRanges = defaultRangeLookupMaxRanges
	}
	if cfg.TransportFactory != nil {
		ds.transportFactory = cfg.TransportFactory
	}
	ds.rpcRetryOptions = base.DefaultRetryOptions()
	if cfg.RPCRetryOptions != nil {
		ds.rpcRetryOptions = *cfg.RPCRetryOptions
	}
	if cfg.RPCContext != nil {
		ds.rpcContext = cfg.RPCContext
		if ds.rpcRetryOptions.Closer == nil {
			ds.rpcRetryOptions.Closer = ds.rpcContext.Stopper.ShouldQuiesce()
		}
	}
	if cfg.SendNextTimeout != 0 {
		ds.sendNextTimeout = cfg.SendNextTimeout
	} else {
		ds.sendNextTimeout = defaultSendNextTimeout
	}

	if g != nil {
		g.RegisterCallback(gossip.KeyFirstRangeDescriptor,
			func(_ string, value roachpb.Value) {
				if log.V(1) {
					var desc roachpb.RangeDescriptor
					if err := value.GetProto(&desc); err != nil {
						log.Errorf(ds.Ctx, "unable to parse gossipped first range descriptor: %s", err)
					} else {
						log.Infof(ds.Ctx,
							"gossipped first range descriptor: %+v", desc.Replicas)
					}
				}
				err := ds.rangeCache.EvictCachedRangeDescriptor(roachpb.RKeyMin, nil, false)
				if err != nil {
					log.Warningf(ds.Ctx, "failed to evict first range descriptor: %s", err)
				}
			})
	}
	return ds
}

// DefaultDBContext returns (a copy of) the default options for
// NewDBWithContext.
func DefaultDBContext() DBContext {
	return DBContext{
		UserPriority:    roachpb.NormalUserPriority,
		TxnRetryOptions: base.DefaultRetryOptions(),
	}
}

// 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)
	}
}

// NewServer creates a Server from a server.Context.
func NewServer(srvCtx Context, stopper *stop.Stopper) (*Server, error) {
	if _, err := net.ResolveTCPAddr("tcp", srvCtx.Addr); err != nil {
		return nil, errors.Errorf("unable to resolve RPC address %q: %v", srvCtx.Addr, err)
	}

	if srvCtx.Ctx == nil {
		srvCtx.Ctx = context.Background()
	}
	if srvCtx.Ctx.Done() != nil {
		panic("context with cancel or deadline")
	}
	if tracing.TracerFromCtx(srvCtx.Ctx) == nil {
		// TODO(radu): instead of modifying srvCtx.Ctx, we should have a separate
		// context.Context inside Server. We will need to rename server.Context
		// though.
		srvCtx.Ctx = tracing.WithTracer(srvCtx.Ctx, tracing.NewTracer())
	}

	if srvCtx.Insecure {
		log.Warning(srvCtx.Ctx, "running in insecure mode, this is strongly discouraged. See --insecure.")
	}
	// Try loading the TLS configs before anything else.
	if _, err := srvCtx.GetServerTLSConfig(); err != nil {
		return nil, err
	}
	if _, err := srvCtx.GetClientTLSConfig(); err != nil {
		return nil, err
	}

	s := &Server{
		mux:     http.NewServeMux(),
		clock:   hlc.NewClock(hlc.UnixNano),
		stopper: stopper,
	}
	// Add a dynamic log tag value for the node ID.
	//
	// We need to pass the server's Ctx as a base context for the various server
	// components, but we won't know the node ID until we Start(). At that point
	// it's too late to change the contexts in the components (various background
	// processes will have already started using the contexts).
	//
	// The dynamic value allows us to add the log tag to the context now and
	// update the value asynchronously. It's not significantly more expensive than
	// a regular tag since it's just doing an (atomic) load when a log/trace
	// message is constructed.
	s.nodeLogTagVal.Set(log.DynamicIntValueUnknown)
	srvCtx.Ctx = log.WithLogTag(srvCtx.Ctx, "n", &s.nodeLogTagVal)
	s.ctx = srvCtx

	s.clock.SetMaxOffset(srvCtx.MaxOffset)

	s.rpcContext = rpc.NewContext(srvCtx.Context, s.clock, s.stopper)
	s.rpcContext.HeartbeatCB = func() {
		if err := s.rpcContext.RemoteClocks.VerifyClockOffset(); err != nil {
			log.Fatal(s.Ctx(), err)
		}
	}
	s.grpc = rpc.NewServer(s.rpcContext)

	s.registry = metric.NewRegistry()
	s.gossip = gossip.New(
		s.Ctx(), s.rpcContext, s.grpc, s.ctx.GossipBootstrapResolvers, s.stopper, s.registry)
	s.storePool = storage.NewStorePool(
		s.gossip,
		s.clock,
		s.rpcContext,
		srvCtx.ReservationsEnabled,
		srvCtx.TimeUntilStoreDead,
		s.stopper,
	)

	// A custom RetryOptions is created which uses stopper.ShouldQuiesce() as
	// the Closer. This prevents infinite retry loops from occurring during
	// graceful server shutdown
	//
	// Such a loop loop occurs with the DistSender attempts a connection to the
	// local server during shutdown, and receives an internal server error (HTTP
	// Code 5xx). This is the correct error for a server to return when it is
	// shutting down, and is normally retryable in a cluster environment.
	// However, on a single-node setup (such as a test), retries will never
	// succeed because the only server has been shut down; thus, thus the
	// DistSender needs to know that it should not retry in this situation.
	retryOpts := base.DefaultRetryOptions()
	retryOpts.Closer = s.stopper.ShouldQuiesce()
	distSenderCfg := kv.DistSenderConfig{
		Ctx:             s.Ctx(),
		Clock:           s.clock,
		RPCContext:      s.rpcContext,
		RPCRetryOptions: &retryOpts,
	}
	s.distSender = kv.NewDistSender(&distSenderCfg, s.gossip)

	txnMetrics := kv.MakeTxnMetrics()
	s.registry.AddMetricStruct(txnMetrics)
	s.txnCoordSender = kv.NewTxnCoordSender(s.Ctx(), s.distSender, s.clock, srvCtx.Linearizable,
		s.stopper, txnMetrics)
	s.db = client.NewDB(s.txnCoordSender)

	s.raftTransport = storage.NewRaftTransport(storage.GossipAddressResolver(s.gossip), s.grpc, s.rpcContext)
//.........这里部分代码省略.........

// waitForStoreFrozen polls the given stores until they all report having no
// unfrozen Replicas (or an error or timeout occurs).
func (s *adminServer) waitForStoreFrozen(
	stream serverpb.Admin_ClusterFreezeServer,
	stores map[roachpb.StoreID]roachpb.NodeID,
	wantFrozen bool,
) error {
	mu := struct {
		sync.Mutex
		oks map[roachpb.StoreID]bool
	}{
		oks: make(map[roachpb.StoreID]bool),
	}

	opts := base.DefaultRetryOptions()
	opts.Closer = s.server.stopper.ShouldDrain()
	opts.MaxRetries = 20
	sem := make(chan struct{}, 256)
	errChan := make(chan error, 1)
	sendErr := func(err error) {
		select {
		case errChan <- err:
		default:
		}
	}

	numWaiting := len(stores) // loop until this drops to zero
	var err error
	for r := retry.Start(opts); r.Next(); {
		mu.Lock()
		for storeID, nodeID := range stores {
			storeID, nodeID := storeID, nodeID // loop-local copies for goroutine
			var nodeDesc roachpb.NodeDescriptor
			if err := s.server.gossip.GetInfoProto(gossip.MakeNodeIDKey(nodeID), &nodeDesc); err != nil {
				sendErr(err)
				break
			}
			addr := nodeDesc.Address.String()

			if _, inflightOrSucceeded := mu.oks[storeID]; inflightOrSucceeded {
				continue
			}
			mu.oks[storeID] = false // mark as inflight
			action := func() (err error) {
				var resp *roachpb.PollFrozenResponse
				defer func() {
					message := fmt.Sprintf("node %d, store %d: ", nodeID, storeID)

					if err != nil {
						message += err.Error()
					} else {
						numMismatching := len(resp.Results)
						mu.Lock()
						if numMismatching == 0 {
							// If the Store is in the right state, mark it as such.
							// This means we won't try it again.
							message += "ready"
							mu.oks[storeID] = true
						} else {
							// Otherwise, forget that we tried the Store so that
							// the retry loop picks it up again.
							message += fmt.Sprintf("%d replicas report wrong status", numMismatching)
							if limit := 10; numMismatching > limit {
								message += " [truncated]: "
								resp.Results = resp.Results[:limit]
							} else {
								message += ": "
							}
							message += fmt.Sprintf("%+v", resp.Results)
							delete(mu.oks, storeID)
						}
						mu.Unlock()
						err = stream.Send(&serverpb.ClusterFreezeResponse{
							Message: message,
						})
					}
				}()
				conn, err := s.server.rpcContext.GRPCDial(addr)
				if err != nil {
					return err
				}
				client := roachpb.NewInternalClient(conn)
				resp, err = client.PollFrozen(context.Background(),
					&roachpb.PollFrozenRequest{
						StoreRequestHeader: roachpb.StoreRequestHeader{
							NodeID:  nodeID,
							StoreID: storeID,
						},
						// If we are looking to freeze everything, we want to
						// collect thawed Replicas, and vice versa.
						CollectFrozen: !wantFrozen,
					})
				return err
			}
			// Run a limited, non-blocking task. That means the task simply
			// won't run if the semaphore is full (or the node is draining).
			// Both are handled by the surrounding retry loop.
			if !s.server.stopper.RunLimitedAsyncTask(sem, func() {
				if err := action(); err != nil {
					sendErr(err)
//.........这里部分代码省略.........

// NewServer creates a Server from a server.Context.
func NewServer(ctx Context, stopper *stop.Stopper) (*Server, error) {
	if _, err := net.ResolveTCPAddr("tcp", ctx.Addr); err != nil {
		return nil, errors.Errorf("unable to resolve RPC address %q: %v", ctx.Addr, err)
	}

	if ctx.Insecure {
		log.Warning(context.TODO(), "running in insecure mode, this is strongly discouraged. See --insecure.")
	}
	// Try loading the TLS configs before anything else.
	if _, err := ctx.GetServerTLSConfig(); err != nil {
		return nil, err
	}
	if _, err := ctx.GetClientTLSConfig(); err != nil {
		return nil, err
	}

	s := &Server{
		Tracer:  tracing.NewTracer(),
		ctx:     ctx,
		mux:     http.NewServeMux(),
		clock:   hlc.NewClock(hlc.UnixNano),
		stopper: stopper,
	}
	s.clock.SetMaxOffset(ctx.MaxOffset)

	s.rpcContext = rpc.NewContext(ctx.Context, s.clock, s.stopper)
	s.rpcContext.HeartbeatCB = func() {
		if err := s.rpcContext.RemoteClocks.VerifyClockOffset(); err != nil {
			log.Fatal(context.TODO(), err)
		}
	}
	s.grpc = rpc.NewServer(s.rpcContext)

	s.registry = metric.NewRegistry()
	s.gossip = gossip.New(s.rpcContext, s.grpc, s.ctx.GossipBootstrapResolvers, s.stopper, s.registry)
	s.storePool = storage.NewStorePool(
		s.gossip,
		s.clock,
		s.rpcContext,
		ctx.ReservationsEnabled,
		ctx.TimeUntilStoreDead,
		s.stopper,
	)

	// A custom RetryOptions is created which uses stopper.ShouldQuiesce() as
	// the Closer. This prevents infinite retry loops from occurring during
	// graceful server shutdown
	//
	// Such a loop loop occurs with the DistSender attempts a connection to the
	// local server during shutdown, and receives an internal server error (HTTP
	// Code 5xx). This is the correct error for a server to return when it is
	// shutting down, and is normally retryable in a cluster environment.
	// However, on a single-node setup (such as a test), retries will never
	// succeed because the only server has been shut down; thus, thus the
	// DistSender needs to know that it should not retry in this situation.
	retryOpts := base.DefaultRetryOptions()
	retryOpts.Closer = s.stopper.ShouldQuiesce()
	s.distSender = kv.NewDistSender(&kv.DistSenderContext{
		Clock:           s.clock,
		RPCContext:      s.rpcContext,
		RPCRetryOptions: &retryOpts,
	}, s.gossip)
	txnMetrics := kv.NewTxnMetrics(s.registry)
	sender := kv.NewTxnCoordSender(s.distSender, s.clock, ctx.Linearizable, s.Tracer,
		s.stopper, txnMetrics)
	s.db = client.NewDB(sender)

	s.raftTransport = storage.NewRaftTransport(storage.GossipAddressResolver(s.gossip), s.grpc, s.rpcContext)

	s.kvDB = kv.NewDBServer(s.ctx.Context, sender, s.stopper)
	roachpb.RegisterExternalServer(s.grpc, s.kvDB)

	// Set up Lease Manager
	var lmKnobs sql.LeaseManagerTestingKnobs
	if ctx.TestingKnobs.SQLLeaseManager != nil {
		lmKnobs = *ctx.TestingKnobs.SQLLeaseManager.(*sql.LeaseManagerTestingKnobs)
	}
	s.leaseMgr = sql.NewLeaseManager(0, *s.db, s.clock, lmKnobs, s.stopper)
	s.leaseMgr.RefreshLeases(s.stopper, s.db, s.gossip)

	// Set up the DistSQL server
	distSQLCtx := distsql.ServerContext{
		Context:    context.Background(),
		DB:         s.db,
		RPCContext: s.rpcContext,
	}
	s.distSQLServer = distsql.NewServer(distSQLCtx)
	distsql.RegisterDistSQLServer(s.grpc, s.distSQLServer)

	// Set up Executor
	eCtx := sql.ExecutorContext{
		Context:      context.Background(),
		DB:           s.db,
		Gossip:       s.gossip,
		LeaseManager: s.leaseMgr,
		Clock:        s.clock,
		DistSQLSrv:   s.distSQLServer,
	}
	if ctx.TestingKnobs.SQLExecutor != nil {
//.........这里部分代码省略.........