In-depth understanding of distributed algorithms and protocols of Go language

import (
    "hash/crc32"
    "sort"
    "strconv"
)

//哈希环
type HashRing []uint32
 
//哈希环的长度
func (hr HashRing) Len() int {
    return len(hr)
}
 
//哈希环上 两个元素的比较规则
func (hr HashRing) Less(i, j int) bool {
    return hr[i] < hr[j]
}
 
//哈希环上两个元素交换规则
func (hr HashRing) Swap(i, j int) {
    hr[i], hr[j] = hr[j], hr[i]
}
 
// 获取哈希值
func hashKey(key string) uint32 {
    return crc32.ChecksumIEEE([]byte(key))
}
 
//向哈希环中添加节点
func (hr *HashRing) AddNode(node ...uint32) {
    *hr = append(*hr, node...)
    sort.Sort(hr)
}
 
//从哈希环中删除节点
func (hr *HashRing) RemoveNode(node uint32) {
    i := hr.search(node)
    if i < len(*hr) && (*hr)[i] == node {
        *hr = append((*hr)[:i], (*hr)[i+1:]...)
    }
}
 
// 查找哈希环上对应的节点
func (hr HashRing) search(key uint32) int {
    i := sort.Search(len(hr), func(i int) bool { return hr[i] >= key })
    if i < len(hr) {
        return i
    } else {
        return 0
    }
}
 
// 根据数据的键值，返回对应的节点，实现数据的负载均衡
func (hr HashRing) GetNode(key string) uint32 {
    if len(hr) == 0 {
        return 0
    }
    k := hashKey(key)
    i := hr.search(k)
    return hr[i%len(hr)]
}

import "github.com/hashicorp/raft"
import "github.com/hashicorp/raft-boltdb"

// 创建raft节点
func createRaftNode(dataDir string, bindAddr string) (*raft.Raft, error) {
    // 初始化raft配置
    config := raft.DefaultConfig()
    config.LocalID = raft.ServerID(bindAddr)
    config.SnapshotInterval = 20 * time.Second
    config.SnapshotThreshold = 2

    // 初始化raft存储
    store, err := raftboltdb.NewBoltStore(filepath.Join(dataDir, "raft.db"))
    if err != nil {
        return nil, err
    }

    // 初始化raft传输
    raftTransport, err := raft.NewTCPTransport(bindAddr, nil, 3, 10*time.Second, os.Stderr)
    if err != nil {
        return nil, err
    }

    // 创建raft实例
    fsm := NewRaftFSM()
    raft := raft.NewRaft(config, fsm, store, store, raftTransport)

    err = raft.SetConfiguration(raft.Configuration{
        Servers: []raft.Server{
            {ID: config.LocalID, Address: raftTransport.LocalAddr()},
        },
    })
    if err != nil {
        return nil, err
    }

    return raft, nil
}

// 创建RaftFSM
type RaftFSM struct{}

func NewRaftFSM() *RaftFSM {
    return &RaftFSM{}
}

func (r *RaftFSM) Apply(log *raft.Log) interface{} {
    return nil
}

func (r *RaftFSM) Snapshot() (raft.FSMSnapshot, error) {
    return nil, nil
}

func (r *RaftFSM) Restore(rc io.ReadCloser) error {
    return nil
}

import (
    "time"
    "github.com/samuel/go-zookeeper/zk"
)

// 创建Zookeeper会话
func createZookeeperSession() (*zk.Conn, error) {
    hosts := []string{"localhost:2181"}
    conn, _, err := zk.Connect(hosts, time.Second*5)
    if err != nil {
        return nil, err
    }
    return conn, nil
}

// 创建Zookeeper节点
func createZookeeperNode(conn *zk.Conn, path string, data string) error {
    _, err := conn.Create(path, []byte(data), 0, zk.WorldACL(zk.PermAll))
    if err != nil {
        return err
    }
    return nil
}

// 获取Zookeeper节点数据
func getZookeeperNodeData(conn *zk.Conn, path string) ([]byte, error) {
    data, _, err := conn.Get(path)
    if err != nil {
        return nil, err
    }
    return data, nil
}