hashring

README

hashring

Implements consistent hashing that can be used when the number of server nodes can increase or decrease (like in memcached). The hashing ring is built using the same algorithm as libketama.

This is a port of Python hash_ring library https://pypi.python.org/pypi/hash_ring/ in Go with the extra methods to add and remove nodes.

Using

Importing ::

import "github.com/serialx/hashring"

Basic example usage ::

memcacheServers := []string{"192.168.0.246:11212",
                            "192.168.0.247:11212",
                            "192.168.0.249:11212"}

ring := hashring.New(memcacheServers)
server, _ := ring.GetNode("my_key")

To fulfill replication requirements, you can also get a list of servers that should store your key.

serversInRing := []string{"192.168.0.246:11212",
                          "192.168.0.247:11212",
                          "192.168.0.248:11212",
                          "192.168.0.249:11212",
                          "192.168.0.250:11212",
                          "192.168.0.251:11212",
                          "192.168.0.252:11212"}

replicaCount := 3
ring := hashring.New(serversInRing)
server, _ := ring.GetNodes("my_key", replicaCount)

Using weights example ::

weights := make(map[string]int)
weights["192.168.0.246:11212"] = 1
weights["192.168.0.247:11212"] = 2
weights["192.168.0.249:11212"] = 1

ring := hashring.NewWithWeights(weights)
server, _ := ring.GetNode("my_key")

Adding and removing nodes example ::

memcacheServers := []string{"192.168.0.246:11212",
                            "192.168.0.247:11212",
                            "192.168.0.249:11212"}

ring := hashring.New(memcacheServers)
ring = ring.RemoveNode("192.168.0.246:11212")
ring = ring.AddNode("192.168.0.250:11212")
server, _ := ring.GetNode("my_key")

Documentation

Index

• type HashKey
• type HashKeyOrder
  • func (h HashKeyOrder) Len() int
  • func (h HashKeyOrder) Less(i, j int) bool
  • func (h HashKeyOrder) Swap(i, j int)
• type HashRing
  • func New(nodes []string) *HashRing
  • func NewWithWeights(weights map[string]int) *HashRing
  • func (h *HashRing) AddNode(node string) *HashRing
  • func (h *HashRing) AddWeightedNode(node string, weight int) *HashRing
  • func (h *HashRing) GenKey(key string) HashKey
  • func (h *HashRing) GetNode(stringKey string) (node string, ok bool)
  • func (h *HashRing) GetNodePos(stringKey string) (pos int, ok bool)
  • func (h *HashRing) GetNodes(stringKey string, size int) (nodes []string, ok bool)
  • func (h *HashRing) RemoveNode(node string) *HashRing
  • func (h *HashRing) Size() int
  • func (h *HashRing) UpdateWeightedNode(node string, weight int) *HashRing
  • func (h *HashRing) UpdateWithWeights(weights map[string]int)
• type HashRingCluster
  • func NewHashRingCluster(numberOfVirtualNodes int) *HashRingCluster
  • func (hc *HashRingCluster) AddServer(name string, rangeString string) error
  • func (hc *HashRingCluster) GetServer(key string) string
  • func (hc *HashRingCluster) GetServerInfo(serverName string) *ServerInfo
  • func (hc *HashRingCluster) Split(serverName string, newServerName string) error
• type ServerInfo
• type VirtualNodeInfo

Types

type HashKey

type HashKey uint32

type HashKeyOrder

type HashKeyOrder []HashKey

func (HashKeyOrder) Len

func (h HashKeyOrder) Len() int

func (HashKeyOrder) Less

func (h HashKeyOrder) Less(i, j int) bool

func (HashKeyOrder) Swap

func (h HashKeyOrder) Swap(i, j int)

type HashRing

type HashRing struct {
	// contains filtered or unexported fields
}

func New

func New(nodes []string) *HashRing

func NewWithWeights

func NewWithWeights(weights map[string]int) *HashRing

func (*HashRing) AddNode

func (h *HashRing) AddNode(node string) *HashRing

func (*HashRing) AddWeightedNode

func (h *HashRing) AddWeightedNode(node string, weight int) *HashRing

func (*HashRing) GenKey

func (h *HashRing) GenKey(key string) HashKey

func (*HashRing) GetNode

func (h *HashRing) GetNode(stringKey string) (node string, ok bool)

func (*HashRing) GetNodePos

func (h *HashRing) GetNodePos(stringKey string) (pos int, ok bool)

func (*HashRing) GetNodes

func (h *HashRing) GetNodes(stringKey string, size int) (nodes []string, ok bool)

func (*HashRing) RemoveNode

func (h *HashRing) RemoveNode(node string) *HashRing

func (*HashRing) Size

func (h *HashRing) Size() int

func (*HashRing) UpdateWeightedNode

func (h *HashRing) UpdateWeightedNode(node string, weight int) *HashRing

func (*HashRing) UpdateWithWeights

func (h *HashRing) UpdateWithWeights(weights map[string]int)

type HashRingCluster

type HashRingCluster struct {
	// contains filtered or unexported fields
}

func NewHashRingCluster

func NewHashRingCluster(numberOfVirtualNodes int) *HashRingCluster

func (*HashRingCluster) AddServer

func (hc *HashRingCluster) AddServer(name string, rangeString string) error

AddServer

rangeString: a-b where a and b are integers >= 0

func (*HashRingCluster) GetServer

func (hc *HashRingCluster) GetServer(key string) string

func (*HashRingCluster) GetServerInfo

func (hc *HashRingCluster) GetServerInfo(serverName string) *ServerInfo

func (*HashRingCluster) Split

func (hc *HashRingCluster) Split(serverName string, newServerName string) error

type ServerInfo

type ServerInfo struct {
	// contains filtered or unexported fields
}

type VirtualNodeInfo

type VirtualNodeInfo struct {
	// contains filtered or unexported fields
}