quorum

Documentation

Index

• Variables
• type Elector
  • func New(m Mode, opts Options) Elector
  • func NewIdleElector(opts Options) Elector
  • func NewSmartElector(opts Options) Elector
• type Mode
• type Options

Variables

var (
	ErrNoAliveFollowers = errors.New("quorum: replica set does not have any alive followers or all of them were excluded from the election")
	ErrNoCandidateFound = errors.New("quorum: no available candidate found")
)

Types

type Elector

type Elector interface {
	// ChooseMaster selects new master and returns back its uuid.
	ChooseMaster(set vshard.ReplicaSet) (vshard.InstanceUUID, error)
	// Mode returns the elector type.
	Mode() Mode
}

func New

func New(m Mode, opts Options) Elector

func NewIdleElector

func NewIdleElector(opts Options) Elector

NewIdleElector returns a new elector based on the follower's idle value.

This elector chooses the candidate to be a master selecting the follower with a minimum idle value.

func NewSmartElector

func NewSmartElector(opts Options) Elector

NewSmartElector returns a new elector based on rules:

• compare vshard configuration consistency,
• compare upstream status,
• compare LSN behind the master,
• compare when replica got last heartbeat signal or data from master,
• user promotion rules based on instance priorities.

type Mode

type Mode string

const (
	ModeIdle  Mode = "idle"
	ModeSmart Mode = "smart"
)

type Options

type Options struct {
	ReasonableFollowerLSNLag int64
	ReasonableFollowerIdle   float64
}