随机挑选目标服务器
package load_balanceimport ( 'errors' 'math/rand')//随机负载均衡type RandomBalance struct { curIndex int rss []string}func (r *RandomBalance) Add(params ...string) error { if len(params) == 0 { return errors.New('params len 1 at least') } addr := params[0] r.rss = append(r.rss, addr) return nil}func (r *RandomBalance) Next() string { if len(r.rss) == 0 { return '' } r.curIndex = rand.Intn(len(r.rss)) return r.rss[r.curIndex]}func (r *RandomBalance) Get(string) (string, error) { return r.Next(), nil}轮询负载
服务器依次轮询
package load_balanceimport 'errors'//轮询负载均衡type RoundRobinBalance struct { curIndex int rss []string}func (r *RoundRobinBalance) Add(params ...string) error { if len(params) == 0 { return errors.New('params len 1 at least') } addr := params[0] r.rss = append(r.rss, addr) return nil}func (r *RoundRobinBalance) Next() string { if len(r.rss) == 0 { return '' } lens := len(r.rss) if r.curIndex >= lens { r.curIndex = 0 } curAddr := r.rss[r.curIndex] r.curIndex = (r.curIndex + 1) % lens return curAddr}func (r *RoundRobinBalance) Get(string) (string, error) { return r.Next(), nil}加权轮询负载
给目标设置访问权重，按照权重轮询
package load_balanceimport ( 'errors' 'strconv')type WeightRoundRobinBalance struct { curIndex int rss []*WeightNode rsw []int}type WeightNode struct { addr string Weight int //初始化时对节点约定的权重 currentWeight int //节点临时权重，每轮都会变化 effectiveWeight int //有效权重, 默认与weight相同 , totalWeight = sum(effectiveWeight) //出现故障就-1}//1, currentWeight = currentWeight + effectiveWeight//2, 选中最大的currentWeight节点为选中节点//3, currentWeight = currentWeight - totalWeightfunc (r *WeightRoundRobinBalance) Add(params ...string) error { if len(params) != 2 { return errors.New('params len need 2') } parInt, err := strconv.ParseInt(params[1], 10, 64) if err != nil { return err } node := &WeightNode{ addr: params[0], Weight: int(parInt), } node.effectiveWeight = node.Weight r.rss = append(r.rss, node) return nil}func (r *WeightRoundRobinBalance) Next() string { var best *WeightNode total := 0 for i := 0; i < len(r.rss); i++ { w := r.rss[i] //1 计算所有有效权重 total += w.effectiveWeight //2 修改当前节点临时权重 w.currentWeight += w.effectiveWeight //3 有效权重默认与权重相同，通讯异常时-1, 通讯成功+1，直到恢复到weight大小 if w.effectiveWeight < w.Weight { w.effectiveWeight++ } //4 选中最大临时权重节点 if best == nil || w.currentWeight > best.currentWeight { best = w } } if best == nil { return '' } //5 变更临时权重为 临时权重-有效权重之和 best.currentWeight -= total return best.addr}func (r *WeightRoundRobinBalance) Get(string) (string, error) { return r.Next(), nil}func (r *WeightRoundRobinBalance) Update() {}一致性hash
请求固定的URL访问指定的IP
package load_balanceimport ( 'errors' 'hash/crc32' 'sort' 'strconv' 'sync')//1 单调性（唯一） 2平衡性 (数据 目标元素均衡) 3分散性(散列)type Hash func(data []byte) uint32type UInt32Slice []uint32func (s UInt32Slice) Len() int { return len(s)}func (s UInt32Slice) Less(i, j int) bool { return s[i] < s[j]}func (s UInt32Slice) Swap(i, j int) { s[i], s[j] = s[j], s[i]}type ConsistentHashBalance struct { mux sync.RWMutex hash Hash replicas int //复制因子 keys UInt32Slice //已排序的节点hash切片 hashMap map[uint32]string //节点哈希和key的map, 键是hash值，值是节点key}func NewConsistentHashBalance(replicas int, fn Hash) *ConsistentHashBalance { m := &ConsistentHashBalance{ replicas: replicas, hash: fn, hashMap: make(map[uint32]string), } if m.hash == nil { //最多32位，保证是一个2^32-1环 m.hash = crc32.ChecksumIEEE } return m}func (c *ConsistentHashBalance) IsEmpty() bool { return len(c.keys) == 0}// Add 方法用来添加缓存节点，参数为节点key，比如使用IPfunc (c *ConsistentHashBalance) Add(params ...string) error { if len(params) == 0 { return errors.New('param len 1 at least') } addr := params[0] c.mux.Lock() defer c.mux.Unlock() // 结合复制因子计算所有虚拟节点的hash值，并存入m.keys中，同时在m.hashMap中保存哈希值和key的映射 for i := 0; i < c.replicas; i++ { hash := c.hash([]byte(strconv.Itoa(i) + addr)) c.keys = append(c.keys, hash) c.hashMap[hash] = addr } // 对所有虚拟节点的哈希值进行排序，方便之后进行二分查找 sort.Sort(c.keys) return nil}// Get 方法根据给定的对象获取最靠近它的那个节点func (c *ConsistentHashBalance) Get(key string) (string, error) { if c.IsEmpty() { return '', errors.New('node is empty') } hash := c.hash([]byte(key)) // 通过二分查找获取最优节点，第一个'服务器hash'值大于'数据hash'值的就是最优'服务器节点' idx := sort.Search(len(c.keys), func(i int) bool { return c.keys[i] >= hash }) // 如果查找结果 大于 服务器节点哈希数组的最大索引，表示此时该对象哈希值位于最后一个节点之后，那么放入第一个节点中 if idx == len(c.keys) { idx = 0 } c.mux.RLock() defer c.mux.RUnlock() return c.hashMap[c.keys[idx]], nil}封装
定义LoadBalance接口
package load_balancetype LoadBalance interface { Add(...string) error Get(string)(string, error)}工厂方法
package load_balancetype LbType intconst ( LbRandom LbType = iota LbRoundRobin LbWeightRoundRobin LbConsistentHash)func LoadBalanceFactory(lbType LbType) LoadBalance { switch lbType { case LbRandom: return &RandomBalance{} case LbConsistentHash: return NewConsistentHashBalance(10, nil) case LbRoundRobin: return &RoundRobinBalance{} case LbWeightRoundRobin: return &WeightRoundRobinBalance{} default: return &RandomBalance{} }}
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