// standardHttp starts serving standard HTTP (api/web) requests, to be used by normal clients
func standardHttp(discovery bool) {
	m := martini.Classic()

	switch strings.ToLower(config.Config.AuthenticationMethod) {
	case "basic":
		{
			if config.Config.HTTPAuthUser == "" {
				// Still allowed; may be disallowed in future versions
				log.Warning("AuthenticationMethod is configured as 'basic' but HTTPAuthUser undefined. Running without authentication.")
			}
			m.Use(auth.Basic(config.Config.HTTPAuthUser, config.Config.HTTPAuthPassword))
		}
	case "multi":
		{
			if config.Config.HTTPAuthUser == "" {
				// Still allowed; may be disallowed in future versions
				log.Fatal("AuthenticationMethod is configured as 'multi' but HTTPAuthUser undefined")
			}

			m.Use(auth.BasicFunc(func(username, password string) bool {
				if username == "readonly" {
					// Will be treated as "read-only"
					return true
				}
				return auth.SecureCompare(username, config.Config.HTTPAuthUser) && auth.SecureCompare(password, config.Config.HTTPAuthPassword)
			}))
		}
	default:
		{
			// We inject a dummy User object because we have function signatures with User argument in api.go
			m.Map(auth.User(""))
		}
	}

	m.Use(gzip.All())
	// Render html templates from templates directory
	m.Use(render.Renderer(render.Options{
		Directory:       "resources",
		Layout:          "templates/layout",
		HTMLContentType: "text/html",
	}))
	m.Use(martini.Static("resources/public"))

	inst.SetMaintenanceOwner(logic.ThisHostname)

	log.Info("Starting HTTP")

	if discovery {
		go logic.ContinuousDiscovery()
	}
	inst.ReadClusterAliases()

	http.API.RegisterRequests(m)
	http.Web.RegisterRequests(m)

	// Serve
	if err := nethttp.ListenAndServe(config.Config.ListenAddress, m); err != nil {
		log.Fatale(err)
	}
}

// ForceRead reads configuration from given file name or bails out if it fails
func ForceRead(file_name string) *Configuration {
	_, err := read(file_name)
	if err != nil {
		log.Fatal("Cannot read config file:", file_name, err)
	}
	return Config
}

// Common code to deduce the instance's instanceKey if not defined.
func deduceInstanceKeyIfNeeded(instance string, instanceKey *inst.InstanceKey) *inst.InstanceKey {
	if instanceKey == nil {
		instanceKey = assignThisInstanceKey()
	}
	if instanceKey == nil {
		log.Fatal("Cannot deduce instance:", instance)
	}
	return instanceKey
}

func getInstanceKey(instanceKey *inst.InstanceKey) *inst.InstanceKey {
	if instanceKey == nil {
		instanceKey = thisInstanceKey
	}
	if instanceKey == nil {
		log.Fatal("Cannot deduce instance key")
	}
	return instanceKey
}

// Common code to deduce the instance's instanceKey if not defined.
func deduceInstanceKeyIfNeeded(instance string, instanceKey *inst.InstanceKey, allowFuzzyMatch bool) *inst.InstanceKey {
	if allowFuzzyMatch {
		instanceKey = inst.ReadFuzzyInstanceKeyIfPossible(instanceKey)
	}
	if instanceKey == nil {
		instanceKey = assignThisInstanceKey()
	}
	if instanceKey == nil {
		log.Fatal("Cannot deduce instance:", instance)
	}
	return instanceKey
}

// read reads configuration from given file, or silently skips if the file does not exist.
// If the file does exist, then it is expected to be in valid JSON format or the function bails out.
func read(file_name string) (*Configuration, error) {
	file, err := os.Open(file_name)
	if err == nil {
		decoder := json.NewDecoder(file)
		err := decoder.Decode(Config)
		if err == nil {
			log.Infof("Read config: %s", file_name)
		} else {
			log.Fatal("Cannot read config file:", file_name, err)
		}
	}
	return Config, err
}

// read reads configuration from given file, or silently skips if the file does not exist.
// If the file does exist, then it is expected to be in valid JSON format or the function bails out.
func read(file_name string) (*Configuration, error) {
	file, err := os.Open(file_name)
	if err == nil {
		decoder := json.NewDecoder(file)
		err := decoder.Decode(Config)
		if err == nil {
			log.Infof("Read config: %s", file_name)
		} else {
			log.Fatal("Cannot read config file:", file_name, err)
		}
		if Config.MySQLOrchestratorCredentialsConfigFile != "" {
			mySQLConfig := struct {
				Client struct {
					User     string
					Password string
				}
			}{}
			err := gcfg.ReadFileInto(&mySQLConfig, Config.MySQLOrchestratorCredentialsConfigFile)
			if err != nil {
				log.Fatalf("Failed to parse gcfg data from file: %+v", err)
			} else {
				log.Debugf("Parsed orchestrator credentials from %s", Config.MySQLOrchestratorCredentialsConfigFile)
				Config.MySQLOrchestratorUser = mySQLConfig.Client.User
				Config.MySQLOrchestratorPassword = mySQLConfig.Client.Password
			}
		}
		if Config.MySQLTopologyCredentialsConfigFile != "" {
			mySQLConfig := struct {
				Client struct {
					User     string
					Password string
				}
			}{}
			err := gcfg.ReadFileInto(&mySQLConfig, Config.MySQLTopologyCredentialsConfigFile)
			if err != nil {
				log.Fatalf("Failed to parse gcfg data from file: %+v", err)
			} else {
				log.Debugf("Parsed topology credentials from %s", Config.MySQLTopologyCredentialsConfigFile)
				Config.MySQLTopologyUser = mySQLConfig.Client.User
				Config.MySQLTopologyPassword = mySQLConfig.Client.Password
			}
		}

	}
	return Config, err
}

// main is the application's entry point. It will either spawn a CLI or HTTP itnerfaces.
func main() {
	configFile := flag.String("config", "", "config file name")
	verbose := flag.Bool("verbose", false, "verbose")
	debug := flag.Bool("debug", false, "debug mode (very verbose)")
	stack := flag.Bool("stack", false, "add stack trace upon error")
	flag.Parse()

	log.SetLevel(log.ERROR)
	if *verbose {
		log.SetLevel(log.INFO)
	}
	if *debug {
		log.SetLevel(log.DEBUG)
	}
	if *stack {
		log.SetPrintStackTrace(*stack)
	}

	log.Info("starting")

	if len(*configFile) > 0 {
		config.ForceRead(*configFile)
	} else {
		config.Read("/etc/orchestrator-agent.conf.json", "conf/orchestrator-agent.conf.json", "orchestrator-agent.conf.json")
	}

	if len(config.Config.AgentsServer) == 0 {
		log.Fatal("AgentsServer unconfigured. Please set to the HTTP address orchestrator serves agents (port is by default 3001)")
	}

	log.Debugf("Process token: %s", agent.ProcessToken.Hash)

	go acceptSignal()

	app.Http()
}

// Cli initiates a command line interface, executing requested command.
func Cli(command string, strict bool, instance string, destination string, owner string, reason string, duration string, pattern string, clusterAlias string, pool string, hostnameFlag string) {
	if instance != "" && !strings.Contains(instance, ":") {
		instance = fmt.Sprintf("%s:%d", instance, config.Config.DefaultInstancePort)
	}
	instanceKey, err := inst.ParseInstanceKey(instance)
	if err != nil {
		instanceKey = nil
	}
	rawInstanceKey, err := inst.NewRawInstanceKey(instance)
	if err != nil {
		rawInstanceKey = nil
	}

	if destination != "" && !strings.Contains(destination, ":") {
		destination = fmt.Sprintf("%s:%d", destination, config.Config.DefaultInstancePort)
	}
	destinationKey, err := inst.ParseInstanceKey(destination)
	if err != nil {
		destinationKey = nil
	}

	if hostname, err := os.Hostname(); err == nil {
		thisInstanceKey = &inst.InstanceKey{Hostname: hostname, Port: int(config.Config.DefaultInstancePort)}
	}
	postponedFunctionsContainer := inst.NewPostponedFunctionsContainer()

	if len(owner) == 0 {
		// get os username as owner
		usr, err := user.Current()
		if err != nil {
			log.Fatale(err)
		}
		owner = usr.Username
	}
	inst.SetMaintenanceOwner(owner)

	skipDatabaseCommands := false
	switch command {
	case "reset-internal-db-deployment":
		skipDatabaseCommands = true
	case "help":
		skipDatabaseCommands = true
	}

	if !skipDatabaseCommands {
		process.ContinuousRegistration(string(process.OrchestratorExecutionCliMode), command)
	}
	// begin commands
	switch command {
	// smart mode
	case registerCliCommand("relocate", "Smart relocation", `Relocate a slave beneath another instance`), registerCliCommand("relocate-below", "Smart relocation", `Synonym to 'relocate', will be deprecated`):
		{
			instanceKey = deduceInstanceKeyIfNeeded(instance, instanceKey)
			if destinationKey == nil {
				log.Fatal("Cannot deduce destination:", destination)
			}
			_, err := inst.RelocateBelow(instanceKey, destinationKey)
			if err != nil {
				log.Fatale(err)
			}
			fmt.Println(fmt.Sprintf("%s<%s", instanceKey.DisplayString(), destinationKey.DisplayString()))
		}
	case registerCliCommand("relocate-slaves", "Smart relocation", `Relocates all or part of the slaves of a given instance under another instance`):
		{
			instanceKey = deduceInstanceKeyIfNeeded(instance, instanceKey)
			if destinationKey == nil {
				log.Fatal("Cannot deduce destination:", destination)
			}
			slaves, _, err, errs := inst.RelocateSlaves(instanceKey, destinationKey, pattern)
			if err != nil {
				log.Fatale(err)
			} else {
				for _, e := range errs {
					log.Errore(e)
				}
				for _, slave := range slaves {
					fmt.Println(slave.Key.DisplayString())
				}
			}
		}
	case registerCliCommand("regroup-slaves", "Smart relocation", `Given an instance, pick one of its slave and make it local master of its siblings`):
		{
			if instanceKey == nil {
				log.Fatal("Cannot deduce instance:", instance)
			}

			lostSlaves, equalSlaves, aheadSlaves, promotedSlave, err := inst.RegroupSlaves(instanceKey, false, func(candidateSlave *inst.Instance) { fmt.Println(candidateSlave.Key.DisplayString()) }, postponedFunctionsContainer)
			postponedFunctionsContainer.InvokePostponed()
			if promotedSlave == nil {
				log.Fatalf("Could not regroup slaves of %+v; error: %+v", *instanceKey, err)
			}
			fmt.Println(fmt.Sprintf("%s lost: %d, trivial: %d, pseudo-gtid: %d",
				promotedSlave.Key.DisplayString(), len(lostSlaves), len(equalSlaves), len(aheadSlaves)))
			if err != nil {
				log.Fatale(err)
			}
		}
		// General replication commands
		// move, binlog file:pos
//.........这里部分代码省略.........

// Cli initiates a command line interface, executing requested command.
func Cli(command string, strict bool, instance string, destination string, owner string, reason string, duration string, pattern string, clusterAlias string, pool string, hostnameFlag string) {

	if instance != "" && !strings.Contains(instance, ":") {
		instance = fmt.Sprintf("%s:%d", instance, config.Config.DefaultInstancePort)
	}
	instanceKey, err := inst.ParseInstanceKey(instance)
	if err != nil {
		instanceKey = nil
	}
	rawInstanceKey, err := inst.NewRawInstanceKey(instance)
	if err != nil {
		rawInstanceKey = nil
	}

	if destination != "" && !strings.Contains(destination, ":") {
		destination = fmt.Sprintf("%s:%d", destination, config.Config.DefaultInstancePort)
	}
	destinationKey, err := inst.ParseInstanceKey(destination)
	if err != nil {
		destinationKey = nil
	}

	if hostname, err := os.Hostname(); err == nil {
		thisInstanceKey = &inst.InstanceKey{Hostname: hostname, Port: int(config.Config.DefaultInstancePort)}
	}

	if len(owner) == 0 {
		// get os username as owner
		usr, err := user.Current()
		if err != nil {
			log.Fatale(err)
		}
		owner = usr.Username
	}
	inst.SetMaintenanceOwner(owner)

	// begin commands
	switch command {
	// Instance meta
	case cliCommand("discover"):
		{
			if instanceKey == nil {
				instanceKey = thisInstanceKey
			}
			if instanceKey == nil {
				log.Fatal("Cannot deduce instance:", instance)
			}
			instance, err := inst.ReadTopologyInstance(instanceKey)
			if err != nil {
				log.Fatale(err)
			}
			fmt.Println(instance.Key.DisplayString())
		}
	case cliCommand("forget"):
		{
			if rawInstanceKey == nil {
				rawInstanceKey = thisInstanceKey
			}
			if rawInstanceKey == nil {
				log.Fatal("Cannot deduce instance:", instance)
			}
			err := inst.ForgetInstance(rawInstanceKey)
			if err != nil {
				log.Fatale(err)
			}
			fmt.Println(rawInstanceKey.DisplayString())
		}
	case cliCommand("resolve"):
		{
			if instanceKey == nil {
				log.Fatal("Cannot deduce instance:", instance)
			}
			if conn, err := net.Dial("tcp", instanceKey.DisplayString()); err == nil {
				conn.Close()
			} else {
				log.Fatale(err)
			}
			fmt.Println(instanceKey.DisplayString())
		}
	case cliCommand("register-hostname-unresolve"):
		{
			if instanceKey == nil {
				instanceKey = thisInstanceKey
			}
			if instanceKey == nil {
				log.Fatal("Cannot deduce instance:", instance)
			}
			err := inst.RegisterHostnameUnresolve(instanceKey, hostnameFlag)
			if err != nil {
				log.Fatale(err)
			}
			fmt.Println(instanceKey.DisplayString())
		}
	case cliCommand("deregister-hostname-unresolve"):
		{
			if instanceKey == nil {
				instanceKey = thisInstanceKey
			}
			if instanceKey == nil {
//.........这里部分代码省略.........

// standardHttp starts serving HTTP or HTTPS (api/web) requests, to be used by normal clients
func standardHttp(discovery bool) {
	m := martini.Classic()

	switch strings.ToLower(config.Config.AuthenticationMethod) {
	case "basic":
		{
			if config.Config.HTTPAuthUser == "" {
				// Still allowed; may be disallowed in future versions
				log.Warning("AuthenticationMethod is configured as 'basic' but HTTPAuthUser undefined. Running without authentication.")
			}
			m.Use(auth.Basic(config.Config.HTTPAuthUser, config.Config.HTTPAuthPassword))
		}
	case "multi":
		{
			if config.Config.HTTPAuthUser == "" {
				// Still allowed; may be disallowed in future versions
				log.Fatal("AuthenticationMethod is configured as 'multi' but HTTPAuthUser undefined")
			}

			m.Use(auth.BasicFunc(func(username, password string) bool {
				if username == "readonly" {
					// Will be treated as "read-only"
					return true
				}
				return auth.SecureCompare(username, config.Config.HTTPAuthUser) && auth.SecureCompare(password, config.Config.HTTPAuthPassword)
			}))
		}
	default:
		{
			// We inject a dummy User object because we have function signatures with User argument in api.go
			m.Map(auth.User(""))
		}
	}

	m.Use(gzip.All())
	// Render html templates from templates directory
	m.Use(render.Renderer(render.Options{
		Directory:       "resources",
		Layout:          "templates/layout",
		HTMLContentType: "text/html",
	}))
	m.Use(martini.Static("resources/public"))
	if config.Config.UseMutualTLS {
		m.Use(ssl.VerifyOUs(config.Config.SSLValidOUs))
	}

	inst.SetMaintenanceOwner(process.ThisHostname)

	if discovery {
		log.Info("Starting Discovery")
		go logic.ContinuousDiscovery()
	}
	log.Info("Registering endpoints")
	http.API.RegisterRequests(m)
	http.Web.RegisterRequests(m)

	// Serve
	if config.Config.ListenSocket != "" {
		log.Infof("Starting HTTP listener on unix socket %v", config.Config.ListenSocket)
		unixListener, err := net.Listen("unix", config.Config.ListenSocket)
		if err != nil {
			log.Fatale(err)
		}
		defer unixListener.Close()
		if err := nethttp.Serve(unixListener, m); err != nil {
			log.Fatale(err)
		}
	} else if config.Config.UseSSL {
		log.Info("Starting HTTPS listener")
		tlsConfig, err := ssl.NewTLSConfig(config.Config.SSLCAFile, config.Config.UseMutualTLS)
		if err != nil {
			log.Fatale(err)
		}
		tlsConfig.InsecureSkipVerify = config.Config.SSLSkipVerify
		if err = ssl.AppendKeyPairWithPassword(tlsConfig, config.Config.SSLCertFile, config.Config.SSLPrivateKeyFile, sslPEMPassword); err != nil {
			log.Fatale(err)
		}
		if err = ssl.ListenAndServeTLS(config.Config.ListenAddress, m, tlsConfig); err != nil {
			log.Fatale(err)
		}
	} else {
		log.Infof("Starting HTTP listener on %+v", config.Config.ListenAddress)
		if err := nethttp.ListenAndServe(config.Config.ListenAddress, m); err != nil {
			log.Fatale(err)
		}
	}
	log.Info("Web server started")
}

// main is the application's entry point.
func main() {
	servers := flag.String("servers", "", "srv1[:port1][,srv2[:port2]...]")
	command := flag.String("c", "", "command, required (exists|get|ls|lsr|create|creater|set|delete|rm|deleter|rmr|getacl|setacl)")
	force := flag.Bool("force", false, "force operation")
	format := flag.String("format", "txt", "output format (txt|json)")
	verbose := flag.Bool("verbose", false, "verbose")
	debug := flag.Bool("debug", false, "debug mode (very verbose)")
	stack := flag.Bool("stack", false, "add stack trace upon error")
	authUser := flag.String("auth_usr", "", "optional, digest scheme, user")
	authPwd := flag.String("auth_pwd", "", "optional, digest scheme, pwd")
	acls := flag.String("acls", "31", "optional, csv list [1|,2|,4|,8|,16|,31]")
	flag.Parse()

	log.SetLevel(log.ERROR)
	if *verbose {
		log.SetLevel(log.INFO)
	}
	if *debug {
		log.SetLevel(log.DEBUG)
	}
	if *stack {
		log.SetPrintStackTrace(*stack)
	}

	log.Info("starting")

	if *servers == "" {
		log.Fatal("Expected comma delimited list of servers via --servers")
	}
	serversArray := strings.Split(*servers, ",")
	if len(serversArray) == 0 {
		log.Fatal("Expected comma delimited list of servers via --servers")
	}

	if len(*command) == 0 {
		log.Fatal("Expected command (-c) (exists|get|ls|lsr|create|creater|set|delete|rm|deleter|rmr|getacl|setacl)")
	}

	if len(flag.Args()) < 1 {
		log.Fatal("Expected path argument")
	}
	path := flag.Arg(0)
	if *command == "ls" {
	} else if strings.HasSuffix(path, "/") {
		log.Fatal("Path must not end with '/'")
	}

	rand.Seed(time.Now().UnixNano())
	zk.SetServers(serversArray)

	if *authUser != "" && *authPwd != "" {
		authExp := fmt.Sprint(*authUser, ":", *authPwd)
		zk.SetAuth("digest", []byte(authExp))
	}

	if *command == "creater" {
		*command = "create"
		*force = true
	}
	switch *command {
	case "exists":
		{
			if exists, err := zk.Exists(path); err == nil && exists {
				output.PrintString([]byte("true"), *format)
			} else {
				log.Fatale(err)
			}
		}
	case "get":
		{
			if result, err := zk.Get(path); err == nil {
				output.PrintString(result, *format)
			} else {
				log.Fatale(err)
			}
		}
	case "getacl":
		{
			if result, err := zk.GetACL(path); err == nil {
				output.PrintStringArray(result, *format)
			} else {
				log.Fatale(err)
			}
		}
	case "ls":
		{
			if result, err := zk.Children(path); err == nil {
				output.PrintStringArray(result, *format)
			} else {
				log.Fatale(err)
			}
		}
	case "lsr":
		{
			if result, err := zk.ChildrenRecursive(path); err == nil {
				output.PrintStringArray(result, *format)
			} else {
				log.Fatale(err)
			}
//.........这里部分代码省略.........

// ContinuousDiscovery starts an asynchronuous infinite discovery process where instances are
// periodically investigated and their status captured, and long since unseen instances are
// purged and forgotten.
func ContinuousDiscovery() {
	if config.Config.DatabaselessMode__experimental {
		log.Fatal("Cannot execute continuous mode in databaseless mode")
	}

	log.Infof("Starting continuous discovery")
	recentDiscoveryOperationKeys = cache.New(time.Duration(config.Config.InstancePollSeconds)*time.Second, time.Second)

	inst.LoadHostnameResolveCache()
	go handleDiscoveryRequests()

	discoveryTick := time.Tick(time.Duration(config.Config.GetDiscoveryPollSeconds()) * time.Second)
	instancePollTick := time.Tick(time.Duration(config.Config.InstancePollSeconds) * time.Second)
	caretakingTick := time.Tick(time.Minute)
	recoveryTick := time.Tick(time.Duration(config.Config.RecoveryPollSeconds) * time.Second)
	var snapshotTopologiesTick <-chan time.Time
	if config.Config.SnapshotTopologiesIntervalHours > 0 {
		snapshotTopologiesTick = time.Tick(time.Duration(config.Config.SnapshotTopologiesIntervalHours) * time.Hour)
	}

	go ometrics.InitGraphiteMetrics()
	go acceptSignals()

	if *config.RuntimeCLIFlags.GrabElection {
		process.GrabElection()
	}
	for {
		select {
		case <-discoveryTick:
			go func() {
				wasAlreadyElected := atomic.LoadInt64(&isElectedNode)
				myIsElectedNode, err := process.AttemptElection()
				if err != nil {
					log.Errore(err)
				}
				if myIsElectedNode {
					atomic.StoreInt64(&isElectedNode, 1)
				} else {
					atomic.StoreInt64(&isElectedNode, 0)
				}

				if myIsElectedNode {
					instanceKeys, err := inst.ReadOutdatedInstanceKeys()
					if err != nil {
						log.Errore(err)
					}

					log.Debugf("outdated keys: %+v", instanceKeys)
					for _, instanceKey := range instanceKeys {
						instanceKey := instanceKey

						if instanceKey.IsValid() {
							discoveryQueue.Push(instanceKey)
						}
					}
					if wasAlreadyElected == 0 {
						// Just turned to be leader!
						go process.RegisterNode("", "", false)
					}
				} else {
					log.Debugf("Not elected as active node; polling")
				}
			}()
		case <-instancePollTick:
			go func() {
				// This tick does NOT do instance poll (these are handled by the oversmapling discoveryTick)
				// But rather should invoke such routinely operations that need to be as (or roughly as) frequent
				// as instance poll
				if atomic.LoadInt64(&isElectedNode) == 1 {
					go inst.UpdateInstanceRecentRelaylogHistory()
					go inst.RecordInstanceCoordinatesHistory()
				}
			}()
		case <-caretakingTick:
			// Various periodic internal maintenance tasks
			go func() {
				if atomic.LoadInt64(&isElectedNode) == 1 {
					go inst.RecordInstanceBinlogFileHistory()
					go inst.ForgetLongUnseenInstances()
					go inst.ForgetUnseenInstancesDifferentlyResolved()
					go inst.ForgetExpiredHostnameResolves()
					go inst.DeleteInvalidHostnameResolves()
					go inst.ReviewUnseenInstances()
					go inst.InjectUnseenMasters()
					go inst.ResolveUnknownMasterHostnameResolves()
					go inst.UpdateClusterAliases()
					go inst.ExpireMaintenance()
					go inst.ExpireDowntime()
					go inst.ExpireCandidateInstances()
					go inst.ExpireHostnameUnresolve()
					go inst.ExpireClusterDomainName()
					go inst.ExpireAudit()
					go inst.ExpireMasterPositionEquivalence()
					go inst.ExpirePoolInstances()
					go inst.FlushNontrivialResolveCacheToDatabase()
					go process.ExpireNodesHistory()
					go process.ExpireAccessTokens()
//.........这里部分代码省略.........

// ContinuousDiscovery starts an asynchronuous infinite discovery process where instances are
// periodically investigated and their status captured, and long since unseen instances are
// purged and forgotten.
func ContinuousDiscovery() {
	if config.Config.DatabaselessMode__experimental {
		log.Fatal("Cannot execute continuous mode in databaseless mode")
	}

	log.Infof("Starting continuous discovery")
	inst.LoadHostnameResolveCacheFromDatabase()
	go handleDiscoveryRequests()

	discoveryTick := time.Tick(time.Duration(config.Config.DiscoveryPollSeconds) * time.Second)
	caretakingTick := time.Tick(time.Minute)
	recoveryTick := time.Tick(time.Duration(config.Config.RecoveryPollSeconds) * time.Second)
	var snapshotTopologiesTick <-chan time.Time
	if config.Config.SnapshotTopologiesIntervalHours > 0 {
		snapshotTopologiesTick = time.Tick(time.Duration(config.Config.SnapshotTopologiesIntervalHours) * time.Hour)
	}

	go ometrics.InitGraphiteMetrics()
	go acceptSignals()

	for {
		select {
		case <-discoveryTick:
			go func() {
				wasAlreadyElected := isElectedNode
				if isElectedNode, _ = process.AttemptElection(); isElectedNode {
					instanceKeys, _ := inst.ReadOutdatedInstanceKeys()
					log.Debugf("outdated keys: %+v", instanceKeys)
					for _, instanceKey := range instanceKeys {
						go func() { discoveryInstanceKeys <- instanceKey }()
					}
					if !wasAlreadyElected {
						// Just turned to be leader!
						go process.RegisterNode("", "", false)
					}
				} else {
					log.Debugf("Not elected as active node; polling")
				}
			}()
		case <-caretakingTick:
			// Various periodic internal maintenance tasks
			go func() {
				if isElectedNode {
					go inst.ForgetLongUnseenInstances()
					go inst.ForgetUnseenInstancesDifferentlyResolved()
					go inst.ForgetExpiredHostnameResolves()
					go inst.DeleteInvalidHostnameResolves()
					go inst.ReviewUnseenInstances()
					go inst.InjectUnseenMasters()
					go inst.ResolveUnknownMasterHostnameResolves()
					go inst.UpdateClusterAliases()
					go inst.ExpireMaintenance()
					go inst.ExpireDowntime()
					go inst.ExpireCandidateInstances()
					go inst.ExpireHostnameUnresolve()
					go inst.ExpireClusterDomainName()
					go inst.ExpireAudit()
					go inst.ExpireMasterPositionEquivalence()
					go inst.FlushNontrivialResolveCacheToDatabase()
					go process.ExpireNodesHistory()
				}
				if !isElectedNode {
					// Take this opportunity to refresh yourself
					go inst.LoadHostnameResolveCacheFromDatabase()
				}
				go inst.ReadClusterAliases()
			}()
		case <-recoveryTick:
			go func() {
				if isElectedNode {
					go ClearActiveFailureDetections()
					go ClearActiveRecoveries()
					go ExpireBlockedRecoveries()
					go AcknowledgeCrashedRecoveries()
					go inst.ExpireInstanceAnalysisChangelog()
					go CheckAndRecover(nil, nil, false)
				}
			}()
		case <-snapshotTopologiesTick:
			go func() {
				go inst.SnapshotTopologies()
			}()
		}
	}
}