Golang實現四種負載均衡的算法(隨機,輪詢等)
隨機負載
隨機挑選目標服務器
package load_balance import ( "errors" "math/rand" ) //隨機負載均衡 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 }
輪詢負載
服務器依次輪詢
package load_balance import "errors" //輪詢負載均衡 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 }
加權輪詢負載
給目標設置訪問權重,按照權重輪詢
package load_balance import ( "errors" "strconv" ) type WeightRoundRobinBalance struct { curIndex int rss []*WeightNode rsw []int } type WeightNode struct { addr string Weight int //初始化時對節點約定的權重 currentWeight int //節點臨時權重,每輪都會變化 effectiveWeight int //有效權重, 默認與weight相同 , totalWeight = sum(effectiveWeight) //出現故障就-1 } //1, currentWeight = currentWeight + effectiveWeight //2, 選中最大的currentWeight節點為選中節點 //3, currentWeight = currentWeight - totalWeight func (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 計算所有有效權重 total += w.effectiveWeight //2 修改當前節點臨時權重 w.currentWeight += w.effectiveWeight //3 有效權重默認與權重相同,通訊異常時-1, 通訊成功+1,直到恢復到weight大小 if w.effectiveWeight < w.Weight { w.effectiveWeight++ } //4 選中最大臨時權重節點 if best == nil || w.currentWeight > best.currentWeight { best = w } } if best == nil { return "" } //5 變更臨時權重為 臨時權重-有效權重之和 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
請求固定的URL訪問指定的IP
package load_balance import ( "errors" "hash/crc32" "sort" "strconv" "sync" ) //1 單調性(唯一) 2平衡性 (數據 目標元素均衡) 3分散性(散列) type Hash func(data []byte) uint32 type UInt32Slice []uint32 func (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 //復制因子 keys UInt32Slice //已排序的節點hash切片 hashMap map[uint32]string //節點哈希和key的map, 鍵是hash值,值是節點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,保證是一個2^32-1環 m.hash = crc32.ChecksumIEEE } return m } func (c *ConsistentHashBalance) IsEmpty() bool { return len(c.keys) == 0 } // Add 方法用來添加緩存節點,參數為節點key,比如使用IP func (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() // 結合復制因子計算所有虛擬節點的hash值,並存入m.keys中,同時在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 } // 對所有虛擬節點的哈希值進行排序,方便之後進行二分查找 sort.Sort(c.keys) return nil } // Get 方法根據給定的對象獲取最靠近它的那個節點 func (c *ConsistentHashBalance) Get(key string) (string, error) { if c.IsEmpty() { return "", errors.New("node is empty") } hash := c.hash([]byte(key)) // 通過二分查找獲取最優節點,第一個"服務器hash"值大於"數據hash"值的就是最優"服務器節點" idx := sort.Search(len(c.keys), func(i int) bool { return c.keys[i] >= hash }) // 如果查找結果 大於 服務器節點哈希數組的最大索引,表示此時該對象哈希值位於最後一個節點之後,那麼放入第一個節點中 if idx == len(c.keys) { idx = 0 } c.mux.RLock() defer c.mux.RUnlock() return c.hashMap[c.keys[idx]], nil }
封裝
定義LoadBalance接口
package load_balance type LoadBalance interface { Add(...string) error Get(string)(string, error) }
工廠方法
package load_balance type LbType int const ( 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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