增加一致性hash的简单实现

consistent_hash/consistent.go

@@ -0,0 +1,103 @@
+// Package consistent_hash...
+//
+// Description : consistent_hash...
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 2021-11-21 4:57 下午
+package consistent_hash
+
+import (
+	"sort"
+	"strconv"
+	"sync"
+)
+
+// New 获取实例
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 5:03 下午 2021/11/21
+func New(replicas int, fn HashFunc) *Consistent {
+	if nil == fn {
+		fn = DefaultHashFunc
+	}
+	return &Consistent{
+		hashFunc: fn,
+		replicas: replicas,
+		keys:     make([]int, 0),
+		hashMap:  make(map[int]string),
+		lock:     &sync.RWMutex{},
+	}
+}
+
+// Consistent ...
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 5:00 下午 2021/11/21
+type Consistent struct {
+	hashFunc HashFunc       // 哈希函数
+	replicas int            // 虚拟的数量
+	keys     []int          // 哈希环
+	hashMap  map[int]string // 虚拟节点与真实节点的映射表
+	lock     *sync.RWMutex  // 锁
+}
+
+// Add 添加节点
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 5:10 下午 2021/11/21
+func (c *Consistent) Add(keyList ...string) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	for _, key := range keyList {
+		for i := 0; i < c.replicas; i++ {
+			hash := int(c.hashFunc([]byte(strconv.Itoa(i) + key)))
+			c.keys = append(c.keys, hash)
+			c.hashMap[hash] = key
+		}
+	}
+	// 哈希值排序
+	sort.Ints(c.keys)
+}
+
+// Get 获取节点
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 5:16 下午 2021/11/21
+func (c *Consistent) Get(key string) string {
+	c.lock.RLock()
+	defer c.lock.Unlock()
+	if len(c.keys) == 0 {
+		return ""
+	}
+	hash := int(c.hashFunc([]byte(key)))
+	// 查找节点索引
+	idx := sort.Search(len(c.keys), func(i int) bool {
+		return c.keys[i] >= hash
+	})
+	return c.hashMap[c.keys[idx%len(c.keys)]]
+}
+
+// Delete 删除一个节点,本质逻辑 : 重建哈希环
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 5:35 下午 2021/11/21
+func (c *Consistent) Delete(key string) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	tmpKeyList := make([]string, 0)
+	for _, k := range c.hashMap {
+		if k == key {
+			continue
+		}
+		tmpKeyList = append(tmpKeyList, k)
+	}
+	c.hashMap = make(map[int]string)
+	c.keys = make([]int, 0)
+	c.Add(tmpKeyList...)
+}

consistent_hash/define.go

@@ -0,0 +1,22 @@
+// Package consistent_hash...
+//
+// Description : consistent_hash...
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 2021-11-21 4:49 下午
+package consistent_hash
+
+import "hash/crc32"
+
+// HashFunc 哈希函数定义
+//
+// Author : go_developer@163.com<白茶清欢>
+//
+// Date : 4:50 下午 2021/11/21
+type HashFunc func(data []byte) uint32
+
+var (
+	// DefaultHashFunc 默认的哈希函数
+	DefaultHashFunc = crc32.ChecksumIEEE
+)