第五周作业

package consistent_hash
import (	"fmt"	"hash/crc32"	"sort"	"sync")
const (	VirtualNodesFactor = 150)
type node struct {	key  string	Data interface{}}
type ConsistentHash struct {	sync.RWMutex	virtualNodes map[uint32]*node	actNodes     map[string]*node	sortRing     []uint32}
func NewConsistentHash() *ConsistentHash {	return &ConsistentHash{		virtualNodes: make(map[uint32]*node),		actNodes:     make(map[string]*node),		sortRing:     []uint32{},	}}
func (c *ConsistentHash) Add(nk string, nd interface{}) bool {	c.Lock()	defer c.Unlock()
	if _, ok := c.actNodes[nk]; ok {		return false	}
	n := &node{		key:  nk,		Data: nd,	}
	for i := 0; i < VirtualNodesFactor; i++ {		c.virtualNodes[c.hashStr(fmt.Sprintf("%s#%d", nk, i))] = n	}
	c.actNodes[nk] = n	c.sortHashRing()
	return true}
func (c *ConsistentHash) Get(key string) *node {	hash := c.hashStr(key)
	c.RLock()	defer c.RUnlock()
	if len(c.virtualNodes) == 0 {		return nil	}
	i := c.search(hash)
	return c.virtualNodes[c.sortRing[i]]}
func (c *ConsistentHash) search(hash uint32) int {	i := sort.Search(len(c.sortRing), func(i int) bool { return c.sortRing[i] >= hash })	if i < len(c.sortRing) {		if i == len(c.sortRing)-1 {			return 0		} else {			return i		}	} else {		return len(c.sortRing) - 1	}}
func (c *ConsistentHash) Remove(key string) {	c.Lock()	defer c.Unlock()
	_, ok := c.actNodes[key]	if !ok {		return	}
	delete(c.actNodes, key)
	for i := 0; i < VirtualNodesFactor; i++ {		delete(c.virtualNodes, c.hashStr(fmt.Sprintf("%s#%d", key, i)))	}
	c.sortHashRing()}
func (c *ConsistentHash) hashStr(key string) uint32 {	return crc32.ChecksumIEEE([]byte(key))}
func (c *ConsistentHash) sortHashRing() {	c.sortRing = []uint32{}	for k := range c.virtualNodes {		c.sortRing = append(c.sortRing, k)	}	sort.Slice(c.sortRing, func(i, j int) bool {		return c.sortRing[i] < c.sortRing[j]	})}