func init() {
	// Register Raft Commands
	raft.RegisterCommand(&AddServiceCommand{})
	raft.RegisterCommand(&UpdateTTLCommand{})
	raft.RegisterCommand(&RemoveServiceCommand{})
	raft.RegisterCommand(&AddCallbackCommand{})
}

func init() {
	// Register Raft Commands
	raft.RegisterCommand(&AddServiceCommand{})
	raft.RegisterCommand(&UpdateTTLCommand{})
	raft.RegisterCommand(&RemoveServiceCommand{})

	expiredCount = metrics.NewCounter()
	metrics.Register("skydns-expired-entries", expiredCount)

	requestCount = metrics.NewCounter()
	metrics.Register("skydns-requests", requestCount)

	addServiceCount = metrics.NewCounter()
	metrics.Register("skydns-add-service-requests", addServiceCount)

	updateTTLCount = metrics.NewCounter()
	metrics.Register("skydns-update-ttl-requests", updateTTLCount)

	getServiceCount = metrics.NewCounter()
	metrics.Register("skydns-get-service-requests", getServiceCount)

	removeServiceCount = metrics.NewCounter()
	metrics.Register("skydns-remove-service-requests", removeServiceCount)

}

func (raftPeer *RaftPeer) ListenAndServe(router *mux.Router, httpServer raft.HTTPMuxer) error {
	var err error
	rand.Seed(time.Now().UnixNano())

	// Setup commands.
	raft.RegisterCommand(&TransactionBatchCommand{})
	raft.RegisterCommand(&SetCommand{})

	if err := os.MkdirAll(raftPeer.path, 0744); err != nil {
		log.Fatalf("Unable to create path: %v", err)
	}

	log.Printf("Initializing Raft Server: %s", raftPeer.path)

	// Initialize and start Raft server.
	transporter := raft.NewHTTPTransporter("/raft")
	//NewServer(name string, path string, transporter Transporter, stateMachine StateMachine, context interface{}, connectionString string) (*Server, error) {
	raftPeer.raftServer, err = raft.NewServer(raftPeer.name, raftPeer.path, transporter, nil, raftPeer.db, "")
	if err != nil {
		log.Fatal(err)
	}
	transporter.Install(raftPeer.raftServer, httpServer)
	raftPeer.raftServer.Start()

	// Join to leader if specified.
	if raftPeer.leaderAddress != "" {
		log.Println("Attempting to join leader:", raftPeer.leaderAddress)

		if !raftPeer.raftServer.IsLogEmpty() {
			log.Fatal("Cannot join with an existing log")
		}
		if err := raftPeer.Join(raftPeer.leaderAddress); err != nil {
			log.Fatal(err)
		}

		// Initialize the server by joining itself.
	} else if raftPeer.raftServer.IsLogEmpty() {
		log.Println("Initializing new cluster")

		_, err := raftPeer.raftServer.Do(&raft.DefaultJoinCommand{
			Name:             raftPeer.raftServer.Name(),
			ConnectionString: raftPeer.connectionString(),
		})
		if err != nil {
			log.Fatal(err)
		}

	} else {
		log.Println("Recovered from log")
	}

	router.HandleFunc("/join", raftPeer.joinHandler).Methods("POST")

	fmt.Printf("Raft listening\n")
	return nil // TODO return errors.
}

func main() {
	go func() {
		//http://localhost:6060/debug/pprof/
		log.Println(http.ListenAndServe("localhost:6060", nil))
	}()

	log.SetFlags(0)
	flag.Parse()
	if verbose {
		log.Print("Verbose logging enabled.")
	}
	if trace {
		raft.SetLogLevel(raft.Trace)
		log.Print("Raft trace debugging enabled.")
	} else if debug {
		raft.SetLogLevel(raft.Debug)
		log.Print("Raft debugging enabled.")
	}

	rand.Seed(time.Now().UnixNano())

	// Setup commands.
	raft.RegisterCommand(&command.SetCommand{})
	raft.RegisterCommand(&command.RemoveTmpDataCommand{})

	// Set the data directory.
	if flag.NArg() == 0 {
		flag.Usage()
		log.Fatal("Data path argument required")
	}
	path := flag.Arg(0)
	if err := os.MkdirAll(path, 0744); err != nil {
		log.Fatalf("Unable to create path: %v", err)
	}

	//	log.Fatalf("join: %v", join)
	//	log.Fatalf(" path: %v", path)

	log.SetFlags(log.LstdFlags)
	s := server.New(path, host, port)

	if true {
		runtime.GOMAXPROCS(runtime.NumCPU())
	}
	addr := fmt.Sprintf("%s:%d", host, tcpSerPort)

	//log.Fatal(s.ListenAndServe(join, addr))
	s.ListenAndServe(join, addr)
	select {}
}

func main() {
	log.SetFlags(0)
	flag.Parse()
	if verbose {
		log.Print("Verbose logging enabled.")
	}
	if trace {
		raft.SetLogLevel(raft.Trace)
		log.Print("Raft trace debugging enabled.")
	} else if debug {
		raft.SetLogLevel(raft.Debug)
		log.Print("Raft debugging enabled.")
	}

	rand.Seed(time.Now().UnixNano())

	// Setup commands.
	raft.RegisterCommand(&command.WriteCommand{})

	// Set the data directory.
	if flag.NArg() == 0 {
		log.Fatal("Data path argument required")
	}
	path := flag.Arg(0)
	if err := os.MkdirAll(path, 0744); err != nil {
		log.Fatalf("Unable to create path: %v", err)
	}

	log.SetFlags(log.LstdFlags)
	s := server.New(path, host, port)
	log.Fatal(s.ListenAndServe(join))
}

// Creates a new server.
func NewRaftServer(config *configuration.Configuration, clusterConfig *ClusterConfiguration) *RaftServer {
	if !registeredCommands {
		registeredCommands = true
		for _, command := range internalRaftCommands {
			raft.RegisterCommand(command)
		}
	}

	s := &RaftServer{
		host:          config.HostnameOrDetect(),
		port:          config.RaftServerPort,
		path:          config.RaftDir,
		clusterConfig: clusterConfig,
		router:        mux.NewRouter(),
		config:        config,
	}
	rand.Seed(time.Now().Unix())
	// Read existing name or generate a new one.
	if b, err := ioutil.ReadFile(filepath.Join(s.path, "name")); err == nil {
		s.name = string(b)
	} else {
		s.name = fmt.Sprintf("%07x", rand.Int())[0:7]
		if err = ioutil.WriteFile(filepath.Join(s.path, "name"), []byte(s.name), 0644); err != nil {
			panic(err)
		}
	}

	return s
}

// Creates a new server.
func NewRaftServer(config *configuration.Configuration, clusterConfig *cluster.ClusterConfiguration) *RaftServer {
	if !registeredCommands {
		registeredCommands = true
		for _, command := range internalRaftCommands {
			raft.RegisterCommand(command)
		}
	}

	s := &RaftServer{
		host:          config.HostnameOrDetect(),
		port:          config.RaftServerPort,
		path:          config.RaftDir,
		bind_address:  config.BindAddress,
		clusterConfig: clusterConfig,
		notLeader:     make(chan bool, 1),
		router:        mux.NewRouter(),
		config:        config,
	}
	// Read existing name or generate a new one.
	if b, err := ioutil.ReadFile(filepath.Join(s.path, "name")); err == nil {
		s.name = string(b)
	} else {
		var i uint64
		if _, err := os.Stat("/dev/random"); err == nil {
			log.Info("Using /dev/random to initialize the raft server name")
			f, err := os.Open("/dev/random")
			if err != nil {
				panic(err)
			}
			defer f.Close()
			readBytes := 0
			b := make([]byte, 8)
			for readBytes < 8 {
				n, err := f.Read(b[readBytes:])
				if err != nil {
					panic(err)
				}
				readBytes += n
			}
			err = binary.Read(bytes.NewBuffer(b), binary.BigEndian, &i)
			if err != nil {
				panic(err)
			}
		} else {
			log.Info("Using rand package to generate raft server name")
			rand.Seed(time.Now().UnixNano())
			i = uint64(rand.Int())
		}
		s.name = fmt.Sprintf("%07x", i)[0:7]
		log.Info("Setting raft name to %s", s.name)
		if err = ioutil.WriteFile(filepath.Join(s.path, "name"), []byte(s.name), 0644); err != nil {
			panic(err)
		}
	}

	return s
}

func startSer() {

	// Setup commands.
	raft.RegisterCommand(&command.SetCommand{})
	raft.RegisterCommand(&command.RemoveTmpDataCommand{})

	path := kPath
	if err := os.MkdirAll(path, 0744); err != nil {
		log.Fatalf("Unable to create path: %v", err)
	}

	log.SetFlags(log.LstdFlags)
	s := server.New(path, host, port)

	addr := fmt.Sprintf("%s:%d", host, tcpSerPort)

	s.ListenAndServe(join, addr)
}

func main() {
	log.SetFlags(0)
	flag.Parse()

	if verbose {
		log.Print("Verbose logging enabled.")
	}

	if trace {
		raft.SetLogLevel(raft.Trace)
		log.Print("Raft trace debugging enabled.")
	} else if debug {
		raft.SetLogLevel(raft.Debug)
		log.Print("Raft debugging enabled.")
	}

	rand.Seed(time.Now().UnixNano())

	raft.RegisterCommand(&WriteCommand{})

	if flag.NArg() == 0 {
		flag.Usage()

		log.Fatal("Data path argument required")
	}

	path := flag.Arg(0)

	if err := os.MkdirAll(path, 0744); err != nil {
		log.Fatalf("Unable to creater path: %s", err.Error())
	}

	log.SetFlags(log.LstdFlags)
	s := NewServer(path, host, port)
	log.Fatal(s.ListenAndServer(join))
}

func main() {
	//defer profile.Start(profile.CPUProfile).Stop()

	var raftdebug, verbose bool
	var listen, join, directory string

	flag.BoolVar(&verbose, "v", false, "Enable debug output")
	flag.BoolVar(&raftdebug, "r", false, "Enable raft debugging")
	flag.StringVar(&listen, "l", "127.0.0.1:4000", "Socket to listen on (Unix or TCP)")
	flag.StringVar(&join, "join", "", "Cluster to join")
	flag.StringVar(&directory, "d", "", "Storage directory")

	dir := filepath.Dir(os.Args[0])
	base := "./" + filepath.Base(os.Args[0])
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, `Usage: %s [options]

SQLCluster is a highly-available SQL store. It accepts commands over
HTTP, and returns the output of commands together with a
SequenceNumber which indicates the ordering in which requests are
being applied. (SequenceNumber is useful for validation, and can
otherwise be ignored.)

Run a cluster as follows:

  cd %s
  %s -d /tmp/sqlcluster/node0 &
  %s -d /tmp/sqlcluster/node1 -l 127.0.0.1:4001 --join 127.0.0.1:4000 &
  %s -d /tmp/sqlcluster/node2 -l 127.0.0.1:4002 --join 127.0.0.1:4000

You can then issue queries using your favorite HTTP client.

  curl 127.0.0.1:4000/sql -d 'CREATE TABLE hello (world int)'
  curl 127.0.0.1:4000/sql -d 'INSERT INTO hello (world) VALUES (1), (2)'
  curl 127.0.0.1:4000/sql -d 'SELECT * FROM hello'

This should return the following sequence of outputs:
  - SequenceNumber: 0

  - SequenceNumber: 1

  - SequenceNumber: 2
    1
    2

By default, SQLCluster will listen on a TCP port. However, if you
specify a listen address that begins with a / or ., that will be
interpeted as Unix path for SQLCluster to listen on. (Note that
Octopus runs using Unix sockets only, but it will probably be more
convient for you to develop using TCP.)

OPTIONS:
`, os.Args[0], dir, base, base, base)
		flag.PrintDefaults()
	}

	flag.Parse()

	if flag.NArg() != 0 {
		flag.Usage()
		os.Exit(1)
	}

	log.SetVerbose(verbose)

	if directory == "" {
		var err error
		directory, err = ioutil.TempDir("/tmp", "node")
		if err != nil {
			log.Fatalf("Could not create temporary base directory: %s", err)
		}
		defer os.RemoveAll(directory)

		log.Printf("Storing state in tmpdir %s", directory)
	} else {
		if err := os.MkdirAll(directory, os.ModeDir|0755); err != nil {
			log.Fatalf("Error while creating storage directory: %s", err)
		}
	}

	log.Printf("Changing directory to %s", directory)
	if err := os.Chdir(directory); err != nil {
		log.Fatalf("Error while changing to storage directory: %s", err)
	}

	// Make sure we don't leave stranded sqlclusters lying around
	go func() {
		for {
			time.Sleep(2 * time.Second)
			if os.Getppid() == 1 {
				log.Fatal("Parent process exited; terminating")
			}
		}
	}()

	runtime.GOMAXPROCS(4)

	rand.Seed(time.Now().UnixNano())
	raft.RegisterCommand(&server.WriteCommand{})
	if raftdebug {
//.........这里部分代码省略.........

func init() {
	raft.RegisterCommand(&AddCommand{})
}

// Starts the server.
func (s *Server) ListenAndServe(primary string) error {
	var err error

	rand.Seed(int64(time.Now().Nanosecond()))

	s.primary = primary
	s.name = "name-" + s.listen

	raft.RegisterCommand(&BatchCommand{})

	// Initialize and start HTTP server.
	s.httpServer = &http.Server{
		Handler: s.router,
	}

	httpTransport := transport.NewClient().GetHTTPClient()

	//log.Printf(("Initializing Raft Server")
	transporter := NewHTTPTransporter("/raft", *httpTransport)
	s.raftServer, err = raft.NewServer(s.name, s.path, transporter, nil, s.db, "")
	if err != nil {
		log.Fatal(err)
	}
	transporter.Install(s.raftServer, s)
	s.raftServer.Start()

	s.raftServer.SetElectionTimeout(400 * time.Millisecond)

	s.raftServer.AddEventListener("addPeer", func(e raft.Event) {
		//log.Printf("Joined!")
		s.joined = true
	})

	s.raftServer.AddEventListener("leaderChange", func(e raft.Event) {
		leader := e.Value().(string)

		if leader == s.name {
			//log.Printf("Leader Changed to %v", leader)

			s.leaderNotify <- leader
		}
	})

	if primary == "" {
		cs, err := transport.Encode(s.listen)

		if err != nil {
			log.Fatal(err)
		}

		//log.Printf(("Starting as Leader")
		_, err = s.raftServer.Do(&raft.DefaultJoinCommand{
			Name:             s.raftServer.Name(),
			ConnectionString: cs,
		})
		//log.Printf(("I am Leader")

		if err != nil {
			log.Fatal(err)
		}
	} else {
		//log.Printf("Waiting 100 milliseconds to join Primary")
		time.AfterFunc(10*time.Millisecond, func() {
			maxTries := 25
			tries := 0
			for !s.joined {
				//log.Printf("Trying to Join")
				tries++
				//log.Printf("Attempting to Join")
				s.Join(primary)
				// if err != nil {
				// 	//log.Printf("Failed to join")
				// } else {
				// 	//log.Printf("Joined!")
				// 	break
				// }

				if tries > maxTries {
					log.Fatal("Could not join!")
				}

				time.Sleep(JOIN_TIMEOUT)
			}
		})
	}

	s.router.HandleFunc("/sql", s.sqlHandler).Methods("POST")
	s.router.HandleFunc("/healthcheck", s.healthcheckHandler).Methods("GET")
	s.router.HandleFunc("/join", s.joinHandler).Methods("POST")
	s.router.HandleFunc("/forward", s.forwardHandler).Methods("POST")

	// Start Unix transport
	l, err := transport.Listen(s.listen)
	if err != nil {
		log.Fatal(err)
	}

	//log.Printf(("Serving?")

//.........这里部分代码省略.........

func NewRaftServer(r *mux.Router, peers []string, httpAddr string, dataDir string, topo *topology.Topology, pulseSeconds int) *RaftServer {
	s := &RaftServer{
		peers:    peers,
		httpAddr: httpAddr,
		dataDir:  dataDir,
		router:   r,
		topo:     topo,
	}

	if glog.V(4) {
		raft.SetLogLevel(2)
	}

	//注册命令以便在Do中回调
	raft.RegisterCommand(&topology.MaxVolumeIdCommand{})

	var err error

	//Creates a new HTTP transporter with the given path prefix.
	transporter := raft.NewHTTPTransporter("/cluster", 0)
	transporter.Transport.MaxIdleConnsPerHost = 1024

	//http://godoc.org/github.com/goraft/raft#RegisterCommand
	s.raftServer, err = raft.NewServer(s.httpAddr, s.dataDir, transporter, nil, topo, "")
	if err != nil {
		glog.V(0).Infoln(err)
		return nil
	}
	transporter.Install(s.raftServer, s)
	s.raftServer.SetHeartbeatInterval(1 * time.Second)
	s.raftServer.SetElectionTimeout(time.Duration(pulseSeconds) * 1150 * time.Millisecond)
	s.raftServer.Start()

	s.router.HandleFunc("/cluster/join", s.joinHandler).Methods("POST")
	s.router.HandleFunc("/cluster/status", s.statusHandler).Methods("GET")

	// Join to leader if specified.
	if len(s.peers) > 0 {
		if !s.raftServer.IsLogEmpty() {
			glog.V(0).Infoln("Starting cluster with existing logs.")
		} else {
			glog.V(0).Infoln("Joining cluster:", strings.Join(s.peers, ","))
			time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
			firstJoinError := s.Join(s.peers)
			if firstJoinError != nil {
				glog.V(0).Infoln("No existing server found. Starting as leader in the new cluster.")
				_, err := s.raftServer.Do(&raft.DefaultJoinCommand{
					Name:             s.raftServer.Name(),
					ConnectionString: "http://" + s.httpAddr,
				})
				if err != nil {
					glog.V(0).Infoln(err)
					return nil
				}
			}
		}

		// Initialize the server by joining itself.
	} else if s.raftServer.IsLogEmpty() {
		glog.V(0).Infoln("Initializing new cluster")

		_, err := s.raftServer.Do(&raft.DefaultJoinCommand{
			Name:             s.raftServer.Name(),
			ConnectionString: "http://" + s.httpAddr,
		})

		if err != nil {
			glog.V(0).Infoln(err)
			return nil
		}

	} else {
		glog.V(0).Infoln("Recovered from log")
	}

	return s
}

func init() {
	raft.RegisterCommand(&putCommand{})
	raft.RegisterCommand(&delCommand{})
	raft.RegisterCommand(&getCommand{})
}