selector

Documentation

Overview

Package selector is a way to pick a list of service nodes

Index

• Variables
• type Filter
  • func FilterEndpoint(name string) Filter
  • func FilterLabel(key, val string) Filter
  • func FilterVersion(version string) Filter
• type Next
  • func Random(services []*registry.Service) Next
  • func RoundRobin(services []*registry.Service) Next
• type Option
  • func Registry(r registry.Registry) Option
  • func SetStrategy(fn Strategy) Option
  • func WithLogger(l logger.Logger) Option
• type Options
• type SelectOption
  • func WithFilter(fn ...Filter) SelectOption
  • func WithStrategy(fn Strategy) SelectOption
• type SelectOptions
• type Selector
  • func NewSelector(opts ...Option) Selector
• type Strategy

Variables

var (
	DefaultSelector = NewSelector()

	ErrNotFound      = errors.New("not found")
	ErrNoneAvailable = errors.New("none available")
)

Types

type Filter

type Filter func([]*registry.Service) []*registry.Service

Filter is used to filter a service during the selection process.

func FilterEndpoint

func FilterEndpoint(name string) Filter

FilterEndpoint is an endpoint based Select Filter which will only return services with the endpoint specified.

func FilterLabel

func FilterLabel(key, val string) Filter

FilterLabel is a label based Select Filter which will only return services with the label specified.

func FilterVersion

func FilterVersion(version string) Filter

FilterVersion is a version based Select Filter which will only return services with the version specified.

type Next

type Next func() (*registry.Node, error)

Next is a function that returns the next node based on the selector's strategy.

func Random

func Random(services []*registry.Service) Next

Random is a random strategy algorithm for node selection.

func RoundRobin

func RoundRobin(services []*registry.Service) Next

RoundRobin is a roundrobin strategy algorithm for node selection.

type Option

type Option func(*Options)

func Registry

func Registry(r registry.Registry) Option

Registry sets the registry used by the selector.

func SetStrategy

func SetStrategy(fn Strategy) Option

SetStrategy sets the default strategy for the selector.

func WithLogger

func WithLogger(l logger.Logger) Option

WithLogger sets the underline logger.

type Options

type Options struct {
	Registry registry.Registry
	Strategy Strategy

	// Other options for implementations of the interface
	// can be stored in a context
	Context context.Context
	// Logger is the underline logger
	Logger logger.Logger
}

type SelectOption

type SelectOption func(*SelectOptions)

SelectOption used when making a select call.

func WithFilter

func WithFilter(fn ...Filter) SelectOption

WithFilter adds a filter function to the list of filters used during the Select call.

func WithStrategy

func WithStrategy(fn Strategy) SelectOption

Strategy sets the selector strategy.

type SelectOptions

type SelectOptions struct {

	// Other options for implementations of the interface
	// can be stored in a context
	Context  context.Context
	Strategy Strategy

	Filters []Filter
}

type Selector

type Selector interface {
	Init(opts ...Option) error
	Options() Options
	// Select returns a function which should return the next node
	Select(service string, opts ...SelectOption) (Next, error)
	// Mark sets the success/error against a node
	Mark(service string, node *registry.Node, err error)
	// Reset returns state back to zero for a service
	Reset(service string)
	// Close renders the selector unusable
	Close() error
	// Name of the selector
	String() string
}

Selector builds on the registry as a mechanism to pick nodes and mark their status. This allows host pools and other things to be built using various algorithms.

func NewSelector

func NewSelector(opts ...Option) Selector

NewSelector creates a new default selector.

type Strategy

type Strategy func([]*registry.Service) Next

Strategy is a selection strategy e.g random, round robin.