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我有 2001、2002、2003 和 2004 的 4nodes 集群。它们使用 goraft 绑定。假设 2001 是主服务器。现在，当它失败时，另一个节点成为服务器。现在我想要的是，成为当前服务器的节点应该发送我是新领导者的消息。那么如何实现呢？我正在使用带有 GORAFD 实现的 GORAFT。我在这里附上源代码。

main.go - 对于客户端

package main

import (
    "flag"
    "fmt"
    "github.com/goraft/raft"
    "github.com/goraft/raftd/command"
    "github.com/goraft/raftd/server"
    "log"
    "math/rand"
    "os"
    "time"
    "strconv"
)

var verbose bool
var trace bool
var debug bool
var host string
var port int
var join string

func init() {
    flag.Parse()
    flag.BoolVar(&verbose, "v", false, "verbose logging")
    flag.BoolVar(&trace, "trace", false, "Raft trace debugging")
    flag.BoolVar(&debug, "debug", false, "Raft debugging")
    flag.StringVar(&host, "h", "localhost", "hostname")
    p,_:=strconv.Atoi(flag.Arg(1))
    flag.IntVar(&port, "p", p, "port")
    flag.StringVar(&join, "join", "", "host:port of leader to join")
    flag.Usage = func() {
        fmt.Fprintf(os.Stderr, "Usage: %s [arguments] <data-path> \n", os.Args[0])
        flag.PrintDefaults()
    }
}

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 {
        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.SetFlags(log.LstdFlags)
    s := server.New(path, host, port)
    log.Fatal(s.ListenAndServe("localhost:2001"))
    fmt.Println("I am changing my status");
}

Main.go - 用于服务器，即 2001

package main

import (
    "flag"
    "fmt"
    "github.com/goraft/raft"
    "github.com/goraft/raftd/command"
    "github.com/goraft/raftd/server"
    "log"
    "math/rand"
    "os"
    "time"
    "strconv"
)

var verbose bool
var trace bool
var debug bool
var host string
var port int
var join string

func init() {
    flag.Parse()
    flag.BoolVar(&verbose, "v", false, "verbose logging")
    flag.BoolVar(&trace, "trace", false, "Raft trace debugging")
    flag.BoolVar(&debug, "debug", false, "Raft debugging")
    flag.StringVar(&host, "h", "localhost", "hostname")
    p,_:=strconv.Atoi(flag.Arg(1))
    flag.IntVar(&port, "p", p, "port")
    flag.StringVar(&join, "join", "", "host:port of leader to join")
    flag.Usage = func() {
        fmt.Fprintf(os.Stderr, "Usage: %s [arguments] <data-path> \n", os.Args[0])
        flag.PrintDefaults()
    }
}

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

通用 Server.go 代码

package server

import (
    "bytes"
    "encoding/json"
    "fmt"
    "github.com/goraft/raft"
    "github.com/goraft/raftd/command"
    "github.com/goraft/raftd/db"
    "github.com/gorilla/mux"
    "io/ioutil"
    "log"
    "math/rand"
    "net/http"
    "path/filepath"
    "sync"
    "time"
)

// The raftd server is a combination of the Raft server and an HTTP
// server which acts as the transport.
type Server struct {
    name       string
    host       string
    port       int
    path       string
    router     *mux.Router
    raftServer raft.Server
    httpServer *http.Server
    db         *db.DB
    mutex      sync.RWMutex
}

// Creates a new server.
func New(path string, host string, port int) *Server {
    s := &Server{
        host:   host,
        port:   port,
        path:   path,
        db:     db.New(),
        router: mux.NewRouter(),
    }

    // Read existing name or generate a new one.
    if b, err := ioutil.ReadFile(filepath.Join(path, "name")); err == nil {
        s.name = string(b)
    } else {
        s.name = fmt.Sprintf("%07x", rand.Int())[0:7]
        if err = ioutil.WriteFile(filepath.Join(path, "name"), []byte(s.name), 0644); err != nil {
            panic(err)
        }
    }

    return s
}

// Returns the connection string.
func (s *Server) connectionString() string {
    return fmt.Sprintf("http://%s:%d", s.host, s.port)
}

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

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

    // Initialize and start Raft server.
    transporter := raft.NewHTTPTransporter("/raft", 200*time.Millisecond)
    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()

    if leader != "" {
        // Join to leader if specified.

        log.Println("Attempting to join leader:", leader)

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

    } else if s.raftServer.IsLogEmpty() {
        // Initialize the server by joining itself.

        log.Println("Initializing new cluster")

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

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

    log.Println("Initializing HTTP server")

    // Initialize and start HTTP server.
    s.httpServer = &http.Server{
        Addr:    fmt.Sprintf(":%d", s.port),
        Handler: s.router,
    }

    s.router.HandleFunc("/db/{key}", s.readHandler).Methods("GET")
    s.router.HandleFunc("/db/{key}", s.writeHandler).Methods("POST")
    s.router.HandleFunc("/join", s.joinHandler).Methods("POST")

    log.Println("Listening at:", s.connectionString())

    return s.httpServer.ListenAndServe()
}

// This is a hack around Gorilla mux not providing the correct net/http
// HandleFunc() interface.
func (s *Server) HandleFunc(pattern string, handler func(http.ResponseWriter, *http.Request)) {
    s.router.HandleFunc(pattern, handler)
}

// Joins to the leader of an existing cluster.
func (s *Server) Join(leader string) error {
    command := &raft.DefaultJoinCommand{
        Name:     s.raftServer.Name(),
        ConnectionString: s.connectionString(),
    }

    var b bytes.Buffer
    json.NewEncoder(&b).Encode(command)
    resp, err := http.Post(fmt.Sprintf("http://%s/join", leader), "application/json", &b)
    if err != nil {
        return err
    }
    resp.Body.Close()

    return nil
}

func (s *Server) joinHandler(w http.ResponseWriter, req *http.Request) {
    command := &raft.DefaultJoinCommand{}

    if err := json.NewDecoder(req.Body).Decode(&command); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }
    if _, err := s.raftServer.Do(command); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }
}

func (s *Server) readHandler(w http.ResponseWriter, req *http.Request) {
    vars := mux.Vars(req)
    value := s.db.Get(vars["key"])
    w.Write([]byte(value))
}

func (s *Server) writeHandler(w http.ResponseWriter, req *http.Request) {
    vars := mux.Vars(req)

    // Read the value from the POST body.
    b, err := ioutil.ReadAll(req.Body)
    if err != nil {
        w.WriteHeader(http.StatusBadRequest)
        return
    }
    value := string(b)

    // Execute the command against the Raft server.
    _, err = s.raftServer.Do(command.NewWriteCommand(vars["key"], value))
    if err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
    }
}

请给出一些解决方案。

4

1 回答 1

1

我做的。

我刚刚在 goraft-library 代码中插入了新行，其中发生了领导者选择。

因此，只需转到 goraft 的 server.go 文件并进行以下更改。

原始 Server.go - 行 [287-309]

// Sets the state of the server.
func (s *server) setState(state string) {
    s.mutex.Lock()
    defer s.mutex.Unlock()

    // Temporarily store previous values.
    prevState := s.state
    prevLeader := s.leader

    // Update state and leader.
    s.state = state
    if state == Leader {
        s.leader = s.Name()
        s.syncedPeer = make(map[string]bool)
    }

    // Dispatch state and leader change events.
    s.DispatchEvent(newEvent(StateChangeEventType, s.state, prevState))

    if prevLeader != s.leader {
        s.DispatchEvent(newEvent(LeaderChangeEventType, s.leader, prevLeader))
    }
}

编辑 Server.go

// Sets the state of the server.
func (s *server) setState(state string) {
    s.mutex.Lock()
    defer s.mutex.Unlock()

    // Temporarily store previous values.
    prevState := s.state
    prevLeader := s.leader

    // Update state and leader.
    s.state = state
    if state == Leader {
        s.leader = s.Name()
        s.syncedPeer = make(map[string]bool)
    }

    // Dispatch state and leader change events.
    s.DispatchEvent(newEvent(StateChangeEventType, s.state, prevState))

    if prevLeader != s.leader {
        fmt.Println("I am the Leader..!!  ",s.connectionString,"   ",s.path)
        s.DispatchEvent(newEvent(LeaderChangeEventType, s.leader, prevLeader))
    }
}

因此它将在活动主服务器的控制台上打印连接Stirng以及当前服务器的存储路径。

于 2016-02-18T05:38:15.020 回答