// Run starts listening for RPC and HTTP requests,
// and blocks until it the process gets a signal.
// It may also listen on a secure port, or on a unix socket.
func Run() {
	onRunHooks.Fire()
	ServeRPC()

	l, err := proc.Listen(fmt.Sprintf("%v", *Port))
	if err != nil {
		log.Fatal(err)
	}

	host, err := netutil.FullyQualifiedHostname()
	if err != nil {
		host, err = os.Hostname()
		if err != nil {
			log.Fatalf("os.Hostname() failed: %v", err)
		}
	}
	ListeningURL = url.URL{
		Scheme: "http",
		Host:   fmt.Sprintf("%v:%v", host, *Port),
		Path:   "/",
	}

	go http.Serve(l, nil)
	serveSecurePort()
	serveSocketFile()

	proc.Wait()
	l.Close()
	log.Info("Entering lameduck mode")
	go onTermHooks.Fire()
	time.Sleep(*LameduckPeriod)
	log.Info("Shutting down")
	Close()
}

// Run starts listening for RPC and HTTP requests,
// and blocks until it the process gets a signal.
// It may also listen on a secure port, or on a unix socket.
func Run() {
	onRunHooks.Fire()
	ServeRPC()

	l, err := proc.Listen(fmt.Sprintf("%v", *Port))
	if err != nil {
		log.Fatal(err)
	}

	host, err := netutil.FullyQualifiedHostname()
	if err != nil {
		host, err = os.Hostname()
		if err != nil {
			log.Fatalf("os.Hostname() failed: %v", err)
		}
	}
	ListeningURL = url.URL{
		Scheme: "http",
		Host:   fmt.Sprintf("%v:%v", host, *Port),
		Path:   "/",
	}

	go http.Serve(l, nil)
	serveSecurePort()
	serveSocketFile()

	proc.Wait()
	l.Close()
	Close()
}

// RunSecure is like Run, but it additionally listens for RPC and HTTP
// requests using TLS on securePort, using the passed certificate,
// key, and CA certificate.
func RunSecure(port int, securePort int, cert, key, caCert string) {
	onRunHooks.Fire()
	ServeRPC()

	l, err := proc.Listen(fmt.Sprintf("%v", port))
	if err != nil {
		log.Fatal(err)
	}

	host, err := netutil.FullyQualifiedHostname()
	if err != nil {
		host, err = os.Hostname()
		if err != nil {
			log.Fatalf("os.Hostname() failed: %v", err)
		}
	}
	ListeningURL = url.URL{
		Scheme: "http",
		Host:   fmt.Sprintf("%v:%v", host, port),
		Path:   "/",
	}

	go http.Serve(l, nil)

	if securePort != 0 {
		log.Infof("listening on secure port %v", securePort)
		SecureServe(fmt.Sprintf(":%d", securePort), cert, key, caCert)
	}
	proc.Wait()
	l.Close()
	Close()
}

func populateListeningURL() {
	host, err := netutil.FullyQualifiedHostname()
	if err != nil {
		host, err = os.Hostname()
		if err != nil {
			log.Fatalf("os.Hostname() failed: %v", err)
		}
	}
	ListeningURL = url.URL{
		Scheme: "http",
		Host:   fmt.Sprintf("%v:%v", host, *Port),
		Path:   "/",
	}
}

func populateListeningURL() {
	host, err := netutil.FullyQualifiedHostname()
	if err != nil {
		host, err = os.Hostname()
		if err != nil {
			log.Fatalf("os.Hostname() failed: %v", err)
		}
	}
	ListeningURL = url.URL{
		Scheme: "http",
		Host:   netutil.JoinHostPort(host, int32(*Port)),
		Path:   "/",
	}
}

//.........这里部分代码省略.........
		lockPath, err := actionNode.LockShard(ctx, agent.TopoServer, *initKeyspace, shard)
		if err != nil {
			return fmt.Errorf("LockShard(%v/%v) failed: %v", *initKeyspace, shard, err)
		}

		// re-read the shard with the lock
		si, err = agent.TopoServer.GetShard(ctx, *initKeyspace, shard)
		if err != nil {
			return actionNode.UnlockShard(ctx, agent.TopoServer, *initKeyspace, shard, lockPath, err)
		}

		// see if we really need to update it now
		if !si.HasCell(agent.TabletAlias.Cell) {
			si.Cells = append(si.Cells, agent.TabletAlias.Cell)

			// write it back
			if err := agent.TopoServer.UpdateShard(ctx, si); err != nil {
				return actionNode.UnlockShard(ctx, agent.TopoServer, *initKeyspace, shard, lockPath, err)
			}
		}

		// and unlock
		if err := actionNode.UnlockShard(ctx, agent.TopoServer, *initKeyspace, shard, lockPath, nil); err != nil {
			return err
		}
	}
	log.Infof("Initializing the tablet for type %v", tabletType)

	// figure out the hostname
	hostname := *tabletHostname
	if hostname != "" {
		log.Infof("Using hostname: %v from -tablet_hostname flag.", hostname)
	} else {
		hostname, err := netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
		log.Infof("Using detected machine hostname: %v To change this, fix your machine network configuration or override it with -tablet_hostname.", hostname)
	}

	// create and populate tablet record
	tablet := &topodatapb.Tablet{
		Alias:          agent.TabletAlias,
		Hostname:       hostname,
		PortMap:        make(map[string]int32),
		Keyspace:       *initKeyspace,
		Shard:          *initShard,
		Type:           tabletType,
		DbNameOverride: *initDbNameOverride,
		Tags:           initTags,
	}
	if port != 0 {
		tablet.PortMap["vt"] = port
	}
	if gRPCPort != 0 {
		tablet.PortMap["grpc"] = gRPCPort
	}
	if err := topo.TabletComplete(tablet); err != nil {
		return fmt.Errorf("InitTablet TabletComplete failed: %v", err)
	}

	// now try to create the record
	err = agent.TopoServer.CreateTablet(ctx, tablet)
	switch err {
	case nil:
		// it worked, we're good, can update the replication graph

// Start validates and updates the topology records for the tablet, and performs
// the initial state change callback to start tablet services.
func (agent *ActionAgent) Start(ctx context.Context, mysqlPort, vtPort, vtsPort, gRPCPort int) error {
	var err error
	if _, err = agent.readTablet(ctx); err != nil {
		return err
	}

	// find our hostname as fully qualified, and IP
	hostname := *tabletHostname
	if hostname == "" {
		hostname, err = netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
	}
	ipAddrs, err := net.LookupHost(hostname)
	if err != nil {
		return err
	}
	ipAddr := ipAddrs[0]

	// Update bind addr for mysql and query service in the tablet node.
	f := func(tablet *topo.Tablet) error {
		tablet.Hostname = hostname
		tablet.IPAddr = ipAddr
		if tablet.Portmap == nil {
			tablet.Portmap = make(map[string]int)
		}
		if mysqlPort != 0 {
			// only overwrite mysql port if we know it, otherwise
			// leave it as is.
			tablet.Portmap["mysql"] = mysqlPort
		}
		tablet.Portmap["vt"] = vtPort
		if vtsPort != 0 {
			tablet.Portmap["vts"] = vtsPort
		} else {
			delete(tablet.Portmap, "vts")
		}
		if gRPCPort != 0 {
			tablet.Portmap["grpc"] = gRPCPort
		} else {
			delete(tablet.Portmap, "grpc")
		}
		return nil
	}
	if err := agent.TopoServer.UpdateTabletFields(ctx, agent.Tablet().Alias, f); err != nil {
		return err
	}

	// Reread to get the changes we just made
	if _, err := agent.readTablet(ctx); err != nil {
		return err
	}

	if err = agent.verifyTopology(ctx); err != nil {
		return err
	}

	if err = agent.verifyServingAddrs(ctx); err != nil {
		return err
	}

	oldTablet := &topo.Tablet{}
	if err = agent.updateState(ctx, oldTablet, "Start"); err != nil {
		log.Warningf("Initial updateState failed, will need a state change before running properly: %v", err)
	}
	return nil
}

// Start validates and updates the topology records for the tablet, and performs
// the initial state change callback to start tablet services.
// If initUpdateStream is set, update stream service will also be registered.
func (agent *ActionAgent) Start(ctx context.Context, mysqlPort, vtPort, gRPCPort int32, initUpdateStream bool) error {
	var err error
	if _, err = agent.updateTabletFromTopo(ctx); err != nil {
		return err
	}

	// find our hostname as fully qualified, and IP
	hostname := *tabletHostname
	if hostname == "" {
		hostname, err = netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
	}
	ipAddrs, err := net.LookupHost(hostname)
	if err != nil {
		return err
	}
	ipAddr := ipAddrs[0]

	// Update bind addr for mysql and query service in the tablet node.
	f := func(tablet *pb.Tablet) error {
		tablet.Hostname = hostname
		tablet.Ip = ipAddr
		if tablet.PortMap == nil {
			tablet.PortMap = make(map[string]int32)
		}
		if mysqlPort != 0 {
			// only overwrite mysql port if we know it, otherwise
			// leave it as is.
			tablet.PortMap["mysql"] = mysqlPort
		}
		if vtPort != 0 {
			tablet.PortMap["vt"] = vtPort
		} else {
			delete(tablet.PortMap, "vt")
		}
		delete(tablet.PortMap, "vts")
		if gRPCPort != 0 {
			tablet.PortMap["grpc"] = gRPCPort
		} else {
			delete(tablet.PortMap, "grpc")
		}
		return nil
	}
	if err := agent.TopoServer.UpdateTabletFields(ctx, agent.Tablet().Alias, f); err != nil {
		return err
	}

	// Reread to get the changes we just made
	tablet, err := agent.updateTabletFromTopo(ctx)
	if err != nil {
		return err
	}

	if err = agent.verifyTopology(ctx); err != nil {
		return err
	}

	if err = agent.verifyServingAddrs(ctx); err != nil {
		return err
	}

	// get and fix the dbname if necessary
	if !agent.DBConfigs.IsZero() {
		// Only for real instances
		// Update our DB config to match the info we have in the tablet
		if agent.DBConfigs.App.DbName == "" {
			agent.DBConfigs.App.DbName = topoproto.TabletDbName(tablet.Tablet)
		}
		agent.DBConfigs.App.Keyspace = tablet.Keyspace
		agent.DBConfigs.App.Shard = tablet.Shard
	}

	// create and register the RPC services from UpdateStream
	// (it needs the dbname, so it has to be delayed up to here,
	// but it has to be before updateState below that may use it)
	if initUpdateStream {
		us := binlog.NewUpdateStream(agent.MysqlDaemon, agent.DBConfigs.App.DbName)
		us.RegisterService()
		agent.UpdateStream = us
	}

	// initialize tablet server
	if err := agent.QueryServiceControl.InitDBConfig(pbq.Target{
		Keyspace:   tablet.Keyspace,
		Shard:      tablet.Shard,
		TabletType: tablet.Type,
	}, agent.DBConfigs, agent.SchemaOverrides, agent.MysqlDaemon); err != nil {
		return fmt.Errorf("failed to InitDBConfig: %v", err)
	}

	// export a few static variables
	if agent.exportStats {
		statsKeyspace := stats.NewString("TabletKeyspace")
		statsShard := stats.NewString("TabletShard")
		statsKeyRangeStart := stats.NewString("TabletKeyRangeStart")
//.........这里部分代码省略.........

// bindAddr: the address for the query service advertised by this agent
func (agent *ActionAgent) Start(mysqlPort, vtPort, vtsPort int) error {
	var err error
	if err = agent.readTablet(); err != nil {
		return err
	}

	if err = agent.resolvePaths(); err != nil {
		return err
	}

	// find our hostname as fully qualified, and IP
	hostname, err := netutil.FullyQualifiedHostname()
	if err != nil {
		return err
	}
	ipAddrs, err := net.LookupHost(hostname)
	if err != nil {
		return err
	}
	ipAddr := ipAddrs[0]

	// Update bind addr for mysql and query service in the tablet node.
	f := func(tablet *topo.Tablet) error {
		// the first four values are for backward compatibility
		tablet.Addr = fmt.Sprintf("%v:%v", hostname, vtPort)
		if vtsPort != 0 {
			tablet.SecureAddr = fmt.Sprintf("%v:%v", hostname, vtsPort)
		}
		tablet.MysqlAddr = fmt.Sprintf("%v:%v", hostname, mysqlPort)
		tablet.MysqlIpAddr = fmt.Sprintf("%v:%v", ipAddr, mysqlPort)

		// new values
		tablet.Hostname = hostname
		tablet.IPAddr = ipAddr
		if tablet.Portmap == nil {
			tablet.Portmap = make(map[string]int)
		}
		tablet.Portmap["mysql"] = mysqlPort
		tablet.Portmap["vt"] = vtPort
		if vtsPort != 0 {
			tablet.Portmap["vts"] = vtsPort
		} else {
			delete(tablet.Portmap, "vts")
		}
		return nil
	}
	if err := agent.TopoServer.UpdateTabletFields(agent.Tablet().Alias, f); err != nil {
		return err
	}

	// Reread to get the changes we just made
	if err := agent.readTablet(); err != nil {
		return err
	}

	data := fmt.Sprintf("host:%v\npid:%v\n", hostname, os.Getpid())

	if err := agent.TopoServer.CreateTabletPidNode(agent.TabletAlias, data, agent.done); err != nil {
		return err
	}

	if err = agent.verifyTopology(); err != nil {
		return err
	}

	if err = agent.verifyServingAddrs(); err != nil {
		return err
	}

	oldTablet := &topo.Tablet{}
	agent.runChangeCallbacks(oldTablet, "Start")

	go agent.actionEventLoop()
	go agent.executeCallbacksLoop()
	return nil
}

// InitTablet initializes the tablet record if necessary.
func (agent *ActionAgent) InitTablet(port, gRPCPort int32) error {
	// it should be either we have all three of init_keyspace,
	// init_shard and init_tablet_type, or none.
	if *initKeyspace == "" && *initShard == "" && *initTabletType == "" {
		// not initializing the record
		return nil
	}
	if *initKeyspace == "" || *initShard == "" || *initTabletType == "" {
		return fmt.Errorf("either need all of init_keyspace, init_shard and init_tablet_type, or none")
	}

	// parse init_tablet_type
	tabletType, err := topoproto.ParseTabletType(*initTabletType)
	if err != nil {
		return fmt.Errorf("invalid init_tablet_type %v: %v", *initTabletType, err)
	}
	if tabletType == topodatapb.TabletType_MASTER {
		// We disallow MASTER, so we don't have to change
		// shard.MasterAlias, and deal with the corner cases.
		return fmt.Errorf("init_tablet_type cannot be master, use replica instead")
	}

	// parse and validate shard name
	shard, _, err := topo.ValidateShardName(*initShard)
	if err != nil {
		return fmt.Errorf("cannot validate shard name %v: %v", *initShard, err)
	}

	// create a context for this whole operation
	ctx, cancel := context.WithTimeout(agent.batchCtx, *initTimeout)
	defer cancel()

	// read the shard, create it if necessary
	log.Infof("Reading shard record %v/%v", *initKeyspace, shard)
	si, err := agent.TopoServer.GetOrCreateShard(ctx, *initKeyspace, shard)
	if err != nil {
		return fmt.Errorf("InitTablet cannot GetOrCreateShard shard: %v", err)
	}
	if si.MasterAlias != nil && topoproto.TabletAliasEqual(si.MasterAlias, agent.TabletAlias) {
		// We're marked as master in the shard record, which could mean the master
		// tablet process was just restarted. However, we need to check if a new
		// master is in the process of taking over. In that case, it will let us
		// know by forcibly updating the old master's tablet record.
		oldTablet, err := agent.TopoServer.GetTablet(ctx, agent.TabletAlias)
		switch err {
		case topo.ErrNoNode:
			// There's no existing tablet record, so we can assume
			// no one has left us a message to step down.
			tabletType = topodatapb.TabletType_MASTER
		case nil:
			if oldTablet.Type == topodatapb.TabletType_MASTER {
				// We're marked as master in the shard record,
				// and our existing tablet record agrees.
				tabletType = topodatapb.TabletType_MASTER
			}
		default:
			return fmt.Errorf("InitTablet failed to read existing tablet record: %v", err)
		}
	}

	// See if we need to add the tablet's cell to the shard's cell list.
	if !si.HasCell(agent.TabletAlias.Cell) {
		si, err = agent.TopoServer.UpdateShardFields(ctx, *initKeyspace, shard, func(si *topo.ShardInfo) error {
			if si.HasCell(agent.TabletAlias.Cell) {
				// Someone else already did it.
				return topo.ErrNoUpdateNeeded
			}
			si.Cells = append(si.Cells, agent.TabletAlias.Cell)
			return nil
		})
		if err != nil {
			return fmt.Errorf("couldn't add tablet's cell to shard record: %v", err)
		}
	}
	log.Infof("Initializing the tablet for type %v", tabletType)

	// figure out the hostname
	hostname := *tabletHostname
	if hostname != "" {
		log.Infof("Using hostname: %v from -tablet_hostname flag.", hostname)
	} else {
		hostname, err := netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
		log.Infof("Using detected machine hostname: %v To change this, fix your machine network configuration or override it with -tablet_hostname.", hostname)
	}

	// create and populate tablet record
	tablet := &topodatapb.Tablet{
		Alias:          agent.TabletAlias,
		Hostname:       hostname,
		PortMap:        make(map[string]int32),
		Keyspace:       *initKeyspace,
		Shard:          *initShard,
		Type:           tabletType,
		DbNameOverride: *initDbNameOverride,
		Tags:           initTags,
	}
//.........这里部分代码省略.........

// Start validates and updates the topology records for the tablet, and performs
// the initial state change callback to start tablet services.
// If initUpdateStream is set, update stream service will also be registered.
func (agent *ActionAgent) Start(ctx context.Context, mysqlPort, vtPort, gRPCPort int32, initUpdateStream bool) error {
	// find our hostname as fully qualified, and IP
	hostname := *tabletHostname
	if hostname == "" {
		var err error
		hostname, err = netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
	}
	ipAddrs, err := net.LookupHost(hostname)
	if err != nil {
		return err
	}
	ipAddr := ipAddrs[0]

	// Update bind addr for mysql and query service in the tablet node.
	f := func(tablet *topodatapb.Tablet) error {
		tablet.Hostname = hostname
		tablet.Ip = ipAddr
		if tablet.PortMap == nil {
			tablet.PortMap = make(map[string]int32)
		}
		if mysqlPort != 0 {
			// only overwrite mysql port if we know it, otherwise
			// leave it as is.
			tablet.PortMap["mysql"] = mysqlPort
		}
		if vtPort != 0 {
			tablet.PortMap["vt"] = vtPort
		} else {
			delete(tablet.PortMap, "vt")
		}
		delete(tablet.PortMap, "vts")
		if gRPCPort != 0 {
			tablet.PortMap["grpc"] = gRPCPort
		} else {
			delete(tablet.PortMap, "grpc")
		}

		// Save the original tablet for ownership tests later.
		agent.initialTablet = tablet
		return nil
	}
	if _, err := agent.TopoServer.UpdateTabletFields(ctx, agent.TabletAlias, f); err != nil {
		return err
	}

	// Verify the topology is correct.
	agent.verifyTopology(ctx)

	// Get and fix the dbname if necessary, only for real instances.
	if !agent.DBConfigs.IsZero() {
		dbname := topoproto.TabletDbName(agent.initialTablet)

		// Update our DB config to match the info we have in the tablet
		if agent.DBConfigs.App.DbName == "" {
			agent.DBConfigs.App.DbName = dbname
		}
		if agent.DBConfigs.Filtered.DbName == "" {
			agent.DBConfigs.Filtered.DbName = dbname
		}
	}

	// create and register the RPC services from UpdateStream
	// (it needs the dbname, so it has to be delayed up to here,
	// but it has to be before updateState below that may use it)
	if initUpdateStream {
		us := binlog.NewUpdateStream(agent.MysqlDaemon, agent.DBConfigs.App.DbName)
		agent.UpdateStream = us
		servenv.OnRun(func() {
			us.RegisterService()
		})
	}
	servenv.OnTerm(func() {
		// Disable UpdateStream (if any) upon entering lameduck.
		// We do this regardless of initUpdateStream, since agent.UpdateStream
		// may have been set from elsewhere.
		if agent.UpdateStream != nil {
			agent.UpdateStream.Disable()
		}
	})

	// initialize tablet server
	if err := agent.QueryServiceControl.InitDBConfig(querypb.Target{
		Keyspace:   agent.initialTablet.Keyspace,
		Shard:      agent.initialTablet.Shard,
		TabletType: agent.initialTablet.Type,
	}, agent.DBConfigs, agent.MysqlDaemon); err != nil {
		return fmt.Errorf("failed to InitDBConfig: %v", err)
	}

	// export a few static variables
	if agent.exportStats {
		statsKeyspace := stats.NewString("TabletKeyspace")
		statsShard := stats.NewString("TabletShard")
		statsKeyRangeStart := stats.NewString("TabletKeyRangeStart")
//.........这里部分代码省略.........

// Start validates and updates the topology records for the tablet, and performs
// the initial state change callback to start tablet services.
func (agent *ActionAgent) Start(ctx context.Context, mysqlPort, vtPort, gRPCPort int32) error {
	var err error
	if _, err = agent.readTablet(ctx); err != nil {
		return err
	}

	// find our hostname as fully qualified, and IP
	hostname := *tabletHostname
	if hostname == "" {
		hostname, err = netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
	}
	ipAddrs, err := net.LookupHost(hostname)
	if err != nil {
		return err
	}
	ipAddr := ipAddrs[0]

	// Update bind addr for mysql and query service in the tablet node.
	f := func(tablet *pb.Tablet) error {
		tablet.Hostname = hostname
		tablet.Ip = ipAddr
		if tablet.PortMap == nil {
			tablet.PortMap = make(map[string]int32)
		}
		if mysqlPort != 0 {
			// only overwrite mysql port if we know it, otherwise
			// leave it as is.
			tablet.PortMap["mysql"] = mysqlPort
		}
		if vtPort != 0 {
			tablet.PortMap["vt"] = vtPort
		} else {
			delete(tablet.PortMap, "vt")
		}
		delete(tablet.PortMap, "vts")
		if gRPCPort != 0 {
			tablet.PortMap["grpc"] = gRPCPort
		} else {
			delete(tablet.PortMap, "grpc")
		}
		return nil
	}
	if err := agent.TopoServer.UpdateTabletFields(ctx, agent.Tablet().Alias, f); err != nil {
		return err
	}

	// Reread to get the changes we just made
	tablet, err := agent.readTablet(ctx)
	if err != nil {
		return err
	}

	if err = agent.verifyTopology(ctx); err != nil {
		return err
	}

	if err = agent.verifyServingAddrs(ctx); err != nil {
		return err
	}

	// initialize tablet server
	if !agent.DBConfigs.IsZero() {
		// Only for real instances
		// Update our DB config to match the info we have in the tablet
		if agent.DBConfigs.App.DbName == "" {
			agent.DBConfigs.App.DbName = topoproto.TabletDbName(tablet.Tablet)
		}
		agent.DBConfigs.App.Keyspace = tablet.Keyspace
		agent.DBConfigs.App.Shard = tablet.Shard
	}
	if err := agent.QueryServiceControl.InitDBConfig(pbq.Target{
		Keyspace:   tablet.Keyspace,
		Shard:      tablet.Shard,
		TabletType: tablet.Type,
	}, agent.DBConfigs, agent.SchemaOverrides, agent.MysqlDaemon); err != nil {
		return fmt.Errorf("failed to InitDBConfig: %v", err)
	}

	// and update our state
	oldTablet := &pb.Tablet{}
	if err = agent.updateState(ctx, oldTablet, "Start"); err != nil {
		log.Warningf("Initial updateState failed, will need a state change before running properly: %v", err)
	}
	return nil
}

// Start validates and updates the topology records for the tablet, and performs
// the initial state change callback to start tablet services.
// If initUpdateStream is set, update stream service will also be registered.
func (agent *ActionAgent) Start(ctx context.Context, mysqlPort, vtPort, gRPCPort int32, initUpdateStream bool) error {
	var err error
	if _, err = agent.updateTabletFromTopo(ctx); err != nil {
		return err
	}

	// find our hostname as fully qualified, and IP
	hostname := *tabletHostname
	if hostname == "" {
		hostname, err = netutil.FullyQualifiedHostname()
		if err != nil {
			return err
		}
	}
	ipAddrs, err := net.LookupHost(hostname)
	if err != nil {
		return err
	}
	ipAddr := ipAddrs[0]

	// Update bind addr for mysql and query service in the tablet node.
	f := func(tablet *topodatapb.Tablet) error {
		tablet.Hostname = hostname
		tablet.Ip = ipAddr
		if tablet.PortMap == nil {
			tablet.PortMap = make(map[string]int32)
		}
		if mysqlPort != 0 {
			// only overwrite mysql port if we know it, otherwise
			// leave it as is.
			tablet.PortMap["mysql"] = mysqlPort
		}
		if vtPort != 0 {
			tablet.PortMap["vt"] = vtPort
		} else {
			delete(tablet.PortMap, "vt")
		}
		delete(tablet.PortMap, "vts")
		if gRPCPort != 0 {
			tablet.PortMap["grpc"] = gRPCPort
		} else {
			delete(tablet.PortMap, "grpc")
		}
		return nil
	}
	if _, err := agent.TopoServer.UpdateTabletFields(ctx, agent.Tablet().Alias, f); err != nil {
		return err
	}

	// Reread to get the changes we just made
	tablet, err := agent.updateTabletFromTopo(ctx)
	if err != nil {
		return err
	}

	// Save the original tablet record as it is now (at startup).
	agent.initialTablet = proto.Clone(tablet).(*topodatapb.Tablet)

	if err = agent.verifyTopology(ctx); err != nil {
		return err
	}

	// get and fix the dbname if necessary
	if !agent.DBConfigs.IsZero() {
		// Only for real instances
		// Update our DB config to match the info we have in the tablet
		if agent.DBConfigs.App.DbName == "" {
			agent.DBConfigs.App.DbName = topoproto.TabletDbName(tablet)
		}
		if agent.DBConfigs.Filtered.DbName == "" {
			agent.DBConfigs.Filtered.DbName = topoproto.TabletDbName(tablet)
		}
		agent.DBConfigs.App.Keyspace = tablet.Keyspace
		agent.DBConfigs.App.Shard = tablet.Shard
	}

	// create and register the RPC services from UpdateStream
	// (it needs the dbname, so it has to be delayed up to here,
	// but it has to be before updateState below that may use it)
	if initUpdateStream {
		us := binlog.NewUpdateStream(agent.MysqlDaemon, agent.DBConfigs.App.DbName)
		agent.UpdateStream = us
		servenv.OnRun(func() {
			us.RegisterService()
		})
	}
	servenv.OnTerm(func() {
		// Disable UpdateStream (if any) upon entering lameduck.
		// We do this regardless of initUpdateStream, since agent.UpdateStream
		// may have been set from elsewhere.
		if agent.UpdateStream != nil {
			agent.UpdateStream.Disable()
		}
	})

	// initialize tablet server
	if err := agent.QueryServiceControl.InitDBConfig(querypb.Target{
//.........这里部分代码省略.........