snowflake

README

snowflake

Here is the twitter blog about snowflake.

• The first bit is an unused assigned bit.
• The second part consists of a 41-bit timestamp (milliseconds) whose value is the offset of the current time relative to a certain time.
• The 5 bits of the third and fourth parts represent the data center and worker node, and the max value is
  2^5-1 = 31.
• The last part consists of 8 bits, which means the length of the serial number generated per millisecond per working node, a maximum of 2^8-1 = 4095 IDs can be generated in the same millisecond.
• In a distributed environment, a five-bit data center and worker mean that can deploy 31 data centers. Each data center can deploy up to 31 nodes.
• The binary length of 41 bits is at most 2^41-1 millisecond = 69 years. So the snowflake algorithm can be used for up to 69 years.

Usage

• Check the example program.

   // Create a node
   n, err := snowflake.NewNode(30, 3)
   if err != nil {
      fmt.Println(err)
   }
    
   // Then, generate a id
   id, err := n.Generate()
   if err != nil {
      fmt.Println(err)
   }

   fmt.Printf("ID: %d\n", id)
   fmt.Printf("String: %s\n", id.String())
   fmt.Printf("Uint64: %d\n", id.UInt64())
   
   fmt.Printf("DecomposeID: %v\n", snowflake.DecomposeID(id))

Test and Benchmarking

• Test:

  go test -v . 

• Benchmark:

  go test -bench=. -count=10 -benchtime=2s . 

Attention

• If you need to handle IDs in Javascript, use a string instead of uint64. Because Javascript's maximum integer value you can safely store 53 bits.

Documentation

Index

• func DecomposeID(id ID) map[string]uint64
• type ID
  • func (f ID) String() string
  • func (f ID) UInt64() uint64
• type Node
  • func NewNode(nodeID, dataCenterID int64) (*Node, error)
  • func (w *Node) Generate() (ID, error)

Functions

func DecomposeID

func DecomposeID(id ID) map[string]uint64

Types

type ID

type ID uint64

func (ID) String

func (f ID) String() string

String returns a string of the snowflake ID

func (ID) UInt64

func (f ID) UInt64() uint64

UInt64 returns a uint64 of the snowflake ID

type Node

type Node struct {

	// Record the time stamp of the last ID
	LastStamp int64

	// ID of the node
	NodeID int64

	// DataCenterID of the node
	DataCenterID int64

	// ID sequence numbers that have been generated in the current millisecond
	// (accumulated from 0)A maximum of 4096 IDs are generated within 1 millisecond
	Sequence int64
	// contains filtered or unexported fields
}

func NewNode

func NewNode(nodeID, dataCenterID int64) (*Node, error)

func (*Node) Generate

func (w *Node) Generate() (ID, error)