consistenthash

A Go library that implements Consistent Hashing (+Block Partitioning)

Programming language: Go

License: MIT License

Tags: Distributed Systems    

README

Consistent Hashing

A Go library that implements Consistent Hashing
This package is implemented based on golang/groupcache package with some improvements

Definitions in this README:
node: Refers to the key which is going to be stored in the hash ring or hash table
rKey: Refers to the request hash which is not going to be stored, it's used to find the upper closest node in the hash ring to the rKey

Improvements:

• Remove function added - sort and remove a node from the hash ring
  
• int hashes replaced with uint32
  
• Number of replicas is now configurable while adding new node
  Note: This is useful when capacity is not the same for all nodes
  

Usage

import (
    chash "github.com/mbrostami/consistenthash"
)

// Create ConsistentHash with 2 replicas
ch := chash.NewConsistentHash(2, nil)
ch.Add("127.0.0.1:1001") // node 1
ch.Add("127.0.0.1:1002") // node 2
ch.AddReplicas("127.0.0.1:1003", 4) // node3 has more capacity so possibility to get assigned request is higher than other nodes 

rKey := "something like request url"
node := ch.Get(rKey) // find upper closest node
fmt.println(node) // this will print out one of the nodes  

Test

Benchmark
go test -bench=.

Race Condition go test --race
Thanks to Mohammad Rajabloo for reporting the race issue

Tests
go test