hasherprovider

README

hasherprovider

The Hasher library implements a hashing algorithm on a given key string or UUID and returns the server to which the request should be sent. Consistent hashing is one such algorithm that minimizes the number of updates required to associate the request with the appropriate server. This addresses the common problem of reassigning servers that arises when using the modulo operation.

Installation

go get github.com/kounkou/hasherprovider

Usage

package main

import (
    "fmt"
    "github.com/kounkou/hasherprovider"
)

const (
	CONSISTENT_HASHING = 0
	RANDOM_HASHING     = 1
	UNIFORM_HASHING    = 2
)

func main() {
	// Create a new HasherProvider object
	hasherprovider := hasherprovider.HasherProvider{ }

	// Get the consistent hashing function
	h, err := hasherprovider.GetHasher(CONSISTENT_HASHING)

    	// Set replicas entities
	h.SetReplicas(1)

	if h == nil || err != nil {
		fmt.Println("Error getting hasher:", err)
		return
	}

	h.AddNode("server1")
	h.AddNode("server2")
	h.AddNode("server3")

	result, err := h.Hash("9", 0)

	if err != nil {
		fmt.Println("Error getting hash for some string `9` ", err)
	}

	if result != "server2" {
		fmt.Errorf("Expected replica to be assigned is server2")
		return
	}

	fmt.Println("Success... !")
}

Algorithms

HasherProvider currently supports 3 algorithms. You might want to choose your hashing algorithm based on the following characteristics :

Hashing Algorithm	Load balanced	Elastic	Fault tolerant	Decentralized
Consistent Hashing	Excellent	Excellent	Excellent	Excellent
Random Hashing	Good	Poor	Good	Poor
Uniform Hashing	Poor	Good	Poor	Excellent

Documentation

Index

• Constants
• type Hasher
• type HasherProvider
  • func (h *HasherProvider) GetHasher(hashFunction int) (Hasher, error)

Constants

const (
	CONSISTENT_HASHING = 0
	RANDOM_HASHING     = 1
	UNIFORM_HASHING    = 2
)

Types

type Hasher

type Hasher interface {
	Hash(uuid string, n int) (string, error)
	AddNode(uuid string)
	RemoveNode(uuid string)
	SetReplicas(replicas int)
}

type HasherProvider

type HasherProvider struct {
	Logger *log.Logger
}

func (*HasherProvider) GetHasher

func (h *HasherProvider) GetHasher(hashFunction int) (Hasher, error)