go语言实现一致性hash算法_语言综合

概述packagetoolimport( "errors" "hash/crc32" "sort" "strconv" "sync")//申明切片类型typeunits[]uint32//返回切片长度func(xunits)Len()int{ returnlen(x)}//比较两个值的大小func(xunits)Less(i,jint)boo

package toolimport (	"errors"	"hash/crc32"	"sort"	"strconv"	"sync")//申明切片类型type units []uint32//返回切片长度func (x units) Len() int {	return len(x)}//比较两个值的大小func (x units) Less(i, j int) bool {	return x[i] < x[j]}//切片中值交换func (x units) Swap(i, j int) {	x[i], x[j] = x[j], x[i]}//当hash环没有数据时，提示错误var emptyErr = errors.New("hash 环为空")//创建结构体，保存一致性hash信息type Consistent struct {	//hash环，key为hash值，值存放的是节点信息	circle map[uint32]string	//已经排序的节点hash切片	sortedHashes units	//虚拟节点个数，用来增加hash的平衡性	virtualNode int	//读写锁	sync.RWMutex}func NewConsistent() *Consistent {	return &Consistent{		//初始化变量		circle: make(map[uint32]string),		//设置虚拟节点个数		virtualNode: 20,	}}//自动生成key值func (c *Consistent) generateKey(element string, index int) string {	//副本key生成逻辑	return element + strconv.Itoa(index)}//获取hash位置func (c *Consistent) hashKey(key string) uint32 {	if len(key) < 64 {		var srcatch [64]byte		copy(srcatch[:], key)		//使用IEEE多项式返回数据的CRC-32校验和		return crc32.ChecksumIEEE(srcatch[:len(key)])	}	return crc32.ChecksumIEEE([]byte(key))}//更新排序，方便查找func (c *Consistent) updateSortedHashes() {	hash := c.sortedHashes[:0]	//判断切片容量是否过大，如果过大则重置	if cap(c.sortedHashes)/(c.virtualNode*4) > len(c.circle) {		hash = nil	}	//添加hash	for k := range c.circle {		hash = append(hash, k)	}	//排序	sort.sort(hash)	c.sortedHashes = hash}//向hash环添加节点func (c *Consistent) Add(element string) {	c.Lock()	defer c.Unlock()	c.add(element)}func (c *Consistent) add(element string) {	//生成虚拟节点	var (		i    int		hash uint32		key  string	)	//循环虚拟节点，设置副本	for i = 0; i < c.virtualNode; i++ {		key = c.generateKey(element, i)		hash = c.hashKey(key)		c.circle[hash] = element	}	//更新排序	c.updateSortedHashes()}func (c *Consistent) remove(element string) {	//生成虚拟节点	var (		i    int		hash uint32		key  string	)	//循环虚拟节点，设置副本	for i = 0; i < c.virtualNode; i++ {		key = c.generateKey(element, i)		hash = c.hashKey(key)		delete(c.circle, hash)	}	//更新排序	c.updateSortedHashes()}//删除节点func (c *Consistent) Remove(element string) {	c.Lock()	defer c.Unlock()	c.remove(element)}//顺时针查找最近的节点func (c *Consistent) search(key uint32) int {	f := func(x int) bool {		return c.sortedHashes[x] > key	}	i := sort.Search(len(c.sortedHashes), f)	if i > len(c.sortedHashes) {		i = 0	}	return i}//根据数据表示，获取对应的服务器节点信息func (c *Consistent)Ger(name string) (string,error){	c.Lock()	defer c.Unlock()	if len(c.circle) == 0 {		return "",emptyErr	}	key := c.hashKey(name)	i := c.search(key)	return c.circle[c.sortedHashes[i]],nil}