rselection

README

pkg/rselection

A lightweight leader election library intended for use with rsnotify. Provides an implementation for Postgresql (using pgx). Also provides an implementation for single-node use where we assume the single node is always the leader.

Provides interfaces for scheduled and persistent tasks that are run on an active leader node.

Documentation

Index

• Constants
• type GenericTask
  • func (t *GenericTask) Name() string
  • func (t *GenericTask) Schedule() Schedule
  • func (t *GenericTask) Type() uint8
• type GenericTaskHandler
  • func NewGenericTaskHandler(cfg GenericTaskHandlerConfig) *GenericTaskHandler
  • func (h *GenericTaskHandler) Handle(b broadcaster.Broadcaster)
  • func (h *GenericTaskHandler) Register(name string, task Task)
  • func (h *GenericTaskHandler) Stop()
  • func (h *GenericTaskHandler) Verify() <-chan chan bool
• type GenericTaskHandlerConfig
• type IntervalSchedule
  • func (c *IntervalSchedule) Next() <-chan time.Time
  • func (*IntervalSchedule) Type() uint8
• type Leader
• type Schedule
• type Task
• type TaskHandler

Constants

const (
	TaskTypePersistent uint8 = 0
	TaskTypeScheduled  uint8 = 1

	ScheduleTypeInterval uint8 = 0
)

Types

type GenericTask

type GenericTask struct {
	TaskName     string
	TaskType     uint8
	TaskSchedule Schedule
}

func (*GenericTask) Name

func (t *GenericTask) Name() string

func (*GenericTask) Schedule

func (t *GenericTask) Schedule() Schedule

func (*GenericTask) Type

func (t *GenericTask) Type() uint8

type GenericTaskHandler

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

func NewGenericTaskHandler

func NewGenericTaskHandler(cfg GenericTaskHandlerConfig) *GenericTaskHandler

func (*GenericTaskHandler) Handle

func (h *GenericTaskHandler) Handle(b broadcaster.Broadcaster)

func (*GenericTaskHandler) Register

func (h *GenericTaskHandler) Register(name string, task Task)

Register adds a task to the handler. It must be called before Handle(). Calling Register after Handle() or registering the same task name twice will cause the program to exit via log.Fatalf.

func (*GenericTaskHandler) Stop

func (h *GenericTaskHandler) Stop()

func (*GenericTaskHandler) Verify

func (h *GenericTaskHandler) Verify() <-chan chan bool

type GenericTaskHandlerConfig

type GenericTaskHandlerConfig struct {
}

type IntervalSchedule

type IntervalSchedule struct {
	Ticker <-chan time.Time
}

func (*IntervalSchedule) Next

func (c *IntervalSchedule) Next() <-chan time.Time

func (*IntervalSchedule) Type

func (*IntervalSchedule) Type() uint8

type Leader

type Leader interface {
	Lead() error
}

type Schedule

type Schedule interface {
	Type() uint8
	Next() <-chan time.Time
}

type Task

type Task interface {
	Name() string
	Type() uint8
	Schedule() Schedule
	Run(ctx context.Context, b broadcaster.Broadcaster)
}

type TaskHandler

type TaskHandler interface {
	Handle(b broadcaster.Broadcaster)
	Register(name string, task Task)
	Stop()
	Verify() <-chan chan bool
}

A TaskHandler runs in the context of a Leader Loop. When the leader loop ends, the TaskHandler stops. A TaskHandler can do two types of work:

• Persistent jobs that run for the duration of the TaskHandler's run loop. Persistent jobs, for instance, can monitor a channel and track heartbeats for macro transactions or in-progress queue work.
• Scheduled jobs that run periodically. Scheduled jobs have a set schedule and run per that schedule during the lifetime of the TaskHandler's run loop.