sharding

Documentation

Index

• Variables
• func IDs(shards []shard.Shard) []uint32
• func NewShards(ids []uint32, state shard.State) []shard.Shard
• type HashFn
  • func DefaultHashFn(length int) HashFn
  • func NewHashFn(length int, seed uint32) HashFn
• type HashGen
  • func NewHashGenWithSeed(seed uint32) HashGen
• type ShardSet
  • func NewEmptyShardSet(fn HashFn) ShardSet
  • func NewShardSet(shards []shard.Shard, fn HashFn) (ShardSet, error)

Variables

var (
	// ErrDuplicateShards returned when shard set is empty
	ErrDuplicateShards = errors.New("duplicate shards")

	// ErrInvalidShardID is returned on an invalid shard ID
	ErrInvalidShardID = errors.New("no shard with given ID")
)

Functions

func IDs

func IDs(shards []shard.Shard) []uint32

IDs returns a new slice of shard IDs for a set of shards

func NewShards

func NewShards(ids []uint32, state shard.State) []shard.Shard

NewShards returns a new slice of shards with a specified state

Types

type HashFn

type HashFn func(id ident.ID) uint32

HashFn is a sharding hash function.

func DefaultHashFn

func DefaultHashFn(length int) HashFn

DefaultHashFn generates a HashFn based on murmur32

func NewHashFn

func NewHashFn(length int, seed uint32) HashFn

NewHashFn generates a HashFN based on murmur32 with a given seed

type HashGen

type HashGen func(length int) HashFn

HashGen generates HashFn based on the length of shards.

func NewHashGenWithSeed

func NewHashGenWithSeed(seed uint32) HashGen

NewHashGenWithSeed generates a HashFnGen based on murmur32 with a given seed

type ShardSet

type ShardSet interface {
	// All returns a slice to the shards in this set.
	All() []shard.Shard

	// AllIDs returns a slice to the shard IDs in this set.
	AllIDs() []uint32

	// Lookup will return a shard for a given identifier.
	Lookup(id ident.ID) uint32

	// LookupStateByID returns the state of the shard with a given ID.
	LookupStateByID(shardID uint32) (shard.State, error)

	// Min returns the smallest shard owned by this shard set.
	Min() uint32

	// Max returns the largest shard owned by this shard set.
	Max() uint32

	// HashFn returns the sharding hash function.
	HashFn() HashFn
}

ShardSet contains a sharding function and a set of shards, this interface allows for potentially out of order shard sets.

func NewEmptyShardSet

func NewEmptyShardSet(fn HashFn) ShardSet

NewEmptyShardSet creates a new sharding scheme with an empty set of shards

func NewShardSet

func NewShardSet(shards []shard.Shard, fn HashFn) (ShardSet, error)

NewShardSet creates a new sharding scheme with a set of shards