doublejump - 又快又简洁的一致性哈希库，Google Jump 算法的改进版

# Overview ***doublejump*** 的核心是 Google Jump 一致性哈希算法，这个实现弥补了该算法的最大缺点：不能删除节点。 # Benchmark ``` BenchmarkDoubleJumpWithoutLock/10-nodes 50000000 27.6 ns/op BenchmarkDoubleJumpWithoutLock/100-nodes 30000000 42.7 ns/op BenchmarkDoubleJumpWithoutLock/1000-nodes 30000000 54.1 ns/op BenchmarkDoubleJump/10-nodes 20000000 72.9 ns/op BenchmarkDoubleJump/100-nodes 20000000 86.1 ns/op BenchmarkDoubleJump/1000-nodes 20000000 97.9 ns/op BenchmarkStathatConsistent/10-nodes 5000000 301 ns/op BenchmarkStathatConsistent/100-nodes 5000000 334 ns/op BenchmarkStathatConsistent/1000-nodes 3000000 444 ns/op BenchmarkSerialxHashring/10-nodes 5000000 280 ns/op BenchmarkSerialxHashring/100-nodes 5000000 340 ns/op BenchmarkSerialxHashring/1000-nodes 3000000 427 ns/op ``` # Example ``` h := NewHash() for i := 0; i < 10; i++ { h.Add(fmt.Sprintf("node%d", i)) } fmt.Println(h.Len()) fmt.Println(h.LooseLen()) fmt.Println(h.Get(1000)) fmt.Println(h.Get(2000)) fmt.Println(h.Get(3000)) h.Remove("node3") fmt.Println(h.Len()) fmt.Println(h.LooseLen()) fmt.Println(h.Get(1000)) fmt.Println(h.Get(2000)) fmt.Println(h.Get(3000)) // Output: // 10 // 10 // node9 // node2 // node3 // 9 // 10 // node9 // node2 // node0 ```