sonyflake

Documentation

Overview

Package sonyflake implements Sonyflake, a distributed unique ID generator inspired by Twitter's Snowflake.

A Sonyflake ID is composed of

39 bits for time in units of 10 msec
 8 bits for a sequence number
16 bits for a machine id

Index

• Constants
• func Decompose(id uint64) map[string]uint64
• func ElapsedTime(id uint64) time.Duration
• func Lower16BitPrivateIP() (uint16, error)
• func MachineID(id uint64) uint64
• func SequenceNumber(id uint64) uint64
• type Settings
• type Sonyflake
  • func NewSonyflake(st Settings) *Sonyflake
  • func (sf *Sonyflake) NextID() (uint64, error)

Constants

const (
	BitLenTime      = 39                               // bit length of time
	BitLenSequence  = 8                                // bit length of sequence number
	BitLenMachineID = 63 - BitLenTime - BitLenSequence // bit length of machine id
)

These constants are the bit lengths of Sonyflake ID parts.

Functions

func Decompose

func Decompose(id uint64) map[string]uint64

Decompose returns a set of Sonyflake ID parts.

func ElapsedTime

func ElapsedTime(id uint64) time.Duration

ElapsedTime returns the elapsed time when the given Sonyflake ID was generated.

func Lower16BitPrivateIP

func Lower16BitPrivateIP() (uint16, error)

func MachineID

func MachineID(id uint64) uint64

MachineID returns the machine ID of a Sonyflake ID.

func SequenceNumber

func SequenceNumber(id uint64) uint64

SequenceNumber returns the sequence number of a Sonyflake ID.

Types

type Settings

type Settings struct {
	StartTime      time.Time
	MachineID      func() (uint16, error)
	CheckMachineID func(uint16) bool
}

Settings configures Sonyflake:

StartTime is the time since which the Sonyflake time is defined as the elapsed time. If StartTime is 0, the start time of the Sonyflake is set to "2014-09-01 00:00:00 +0000 UTC". If StartTime is ahead of the current time, Sonyflake is not created.

MachineID returns the unique ID of the Sonyflake instance. If MachineID returns an error, Sonyflake is not created. If MachineID is nil, default MachineID is used. Default MachineID returns the lower 16 bits of the private IP address.

CheckMachineID validates the uniqueness of the machine ID. If CheckMachineID returns false, Sonyflake is not created. If CheckMachineID is nil, no validation is done.

type Sonyflake

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

Sonyflake is a distributed unique ID generator.

func NewSonyflake

func NewSonyflake(st Settings) *Sonyflake

NewSonyflake returns a new Sonyflake configured with the given Settings. NewSonyflake returns nil in the following cases: - Settings.StartTime is ahead of the current time. - Settings.MachineID returns an error. - Settings.CheckMachineID returns false.

func (*Sonyflake) NextID

func (sf *Sonyflake) NextID() (uint64, error)

NextID generates a next unique ID. After the Sonyflake time overflows, NextID returns an error.