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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:
Removefunction 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
go get github.com/mbrostami/consistenthash
import (
"github.com/mbrostami/consistenthash"
)
// Create ConsistentHash with 2 replicas
ch := consistenthash.New(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
Documentation
¶
Overview ¶
Package consistenthash provides an implementation of a ring hash.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ConsistentHash ¶
type ConsistentHash struct {
// contains filtered or unexported fields
}
ConsistentHash everything we need for CH
func New ¶ added in v1.0.0
func New(replicas int, hashFunction HashFunc) *ConsistentHash
New makes new ConsistentHash
func (*ConsistentHash) Add ¶
func (ch *ConsistentHash) Add(key string)
Add adds some keys to the hash key can be also ip:port of a replica
func (*ConsistentHash) AddReplicas ¶
func (ch *ConsistentHash) AddReplicas(key string, replicas int)
AddReplicas adds key and generates "replicas" number of hashes in ring key can be also ip:port of a replica
func (*ConsistentHash) Get ¶
func (ch *ConsistentHash) Get(key string) string
Get gets the closest item in the hash ring to the provided key e.g. key = "request url" O(log n)
func (*ConsistentHash) IsEmpty ¶
func (ch *ConsistentHash) IsEmpty() bool
IsEmpty returns true if there are no items available
func (*ConsistentHash) Remove ¶
func (ch *ConsistentHash) Remove(key string) bool
Remove removes the key from hash table
Source Files