直接上代码,windows7,go1.7下直接运行。
package main
import (
"fmt"
"sort"
"strconv"
"hash/crc32"
"sync"
)
const DEFAULT_REPLICAS = 160
type HashRing []uint32
func (c HashRing) Len() int {
return len(c)
}
func (c HashRing) Less(i,j int) bool {
return c[i] < c[j]
}
func (c HashRing) Swap(i,j int) {
c[i],c[j] = c[j],c[i]
}
type Node struct {
Id int
Ip string
Port int
HostName string
Weight int
}
func NewNode(id int,ip string,port int,name string,weight int) *Node {
return &Node{
Id: id,Ip: ip,Port: port,HostName: name,Weight: weight,}
}
type Consistent struct {
Nodes map[uint32]Node
numReps int
Resources map[int]bool
ring HashRing
sync.RWMutex
}
func NewConsistent() *Consistent {
return &Consistent{
Nodes: make(map[uint32]Node),numReps: DEFAULT_REPLICAS,Resources: make(map[int]bool),ring: HashRing{},}
}
func (c *Consistent) Add(node *Node) bool {
c.Lock()
defer c.Unlock()
if _,ok := c.Resources[node.Id]; ok {
return false
}
count := c.numReps * node.Weight
for i := 0; i < count; i++ {
str := c.joinStr(i,node)
c.Nodes[c.hashStr(str)] = *(node)
}
c.Resources[node.Id] = true
c.sortHashRing()
return true
}
func (c *Consistent) sortHashRing() {
c.ring = HashRing{}
for k := range c.Nodes {
c.ring = append(c.ring,k)
}
sort.Sort(c.ring)
}
func (c *Consistent) joinStr(i int,node *Node) string {
return node.Ip + "*" + strconv.Itoa(node.Weight) +
"-" + strconv.Itoa(i) +
"-" + strconv.Itoa(node.Id)
}
// MurMurHash算法 :https://github.com/spaolacci/murmur3
func (c *Consistent) hashStr(key string) uint32 {
return crc32.ChecksumIEEE([]byte(key))
}
func (c *Consistent) Get(key string) Node {
c.RLock()
defer c.RUnlock()
hash := c.hashStr(key)
i := c.search(hash)
return c.Nodes[c.ring[i]]
}
func (c *Consistent) search(hash uint32) int {
i := sort.Search(len(c.ring),func(i int) bool { return c.ring[i] >= hash })
if i < len(c.ring) {
if i == len(c.ring)-1 {
return 0
} else {
return i
}
} else {
return len(c.ring) - 1
}
}
func (c *Consistent) Remove(node *Node) {
c.Lock()
defer c.Unlock()
if _,ok := c.Resources[node.Id]; !ok {
return
}
delete(c.Resources,node.Id)
count := c.numReps * node.Weight
for i := 0; i < count; i++ {
str := c.joinStr(i,node)
delete(c.Nodes,c.hashStr(str))
}
c.sortHashRing()
}
func main() {
cHashRing := NewConsistent()
for i := 0; i < 10; i++ {
si := fmt.Sprintf("%d",i)
cHashRing.Add(NewNode(i,"172.18.1."+si, 8080,"host_"+si, 1))
}
for k,v := range cHashRing.Nodes {
fmt.Println("Hash:",k," IP:",v.Ip)
}
ipMap := make(map[string]int, 0)
for i := 0; i < 1000; i++ {
si := fmt.Sprintf("key%d",i)
k := cHashRing.Get(si)
if _,ok := ipMap[k.Ip]; ok {
ipMap[k.Ip] += 1
} else {
ipMap[k.Ip] = 1
}
}
for k,v := range ipMap {
fmt.Println("Node IP:"," count:",v)
}
}