roundrobin

Documentation

Overview

Dynamic weighted round robin load balancer

Index

• Constants
• type EndpointOptions
• type EndpointWeight
  • func (ew *EndpointWeight) GetEndpoint() *WeightedEndpoint
  • func (ew *EndpointWeight) GetWeight() int
  • func (ew *EndpointWeight) SetWeight(w int)
• type FSMHandler
  • func NewFSMHandler() (*FSMHandler, error)
  • func NewFSMHandlerWithOptions(timeProvider timetools.TimeProvider) (*FSMHandler, error)
  • func (fsm *FSMHandler) AdjustWeights() ([]SuggestedWeight, error)
  • func (fsm *FSMHandler) Init(endpoints []*WeightedEndpoint)
• type FailureHandler
• type Options
• type RoundRobin
  • func NewRoundRobin() (*RoundRobin, error)
  • func NewRoundRobinWithOptions(o Options) (*RoundRobin, error)
  • func (rr *RoundRobin) AddEndpoint(endpoint endpoint.Endpoint) error
  • func (r *RoundRobin) AddEndpointWithOptions(endpoint endpoint.Endpoint, options EndpointOptions) error
  • func (r *RoundRobin) FindEndpointById(id string) *WeightedEndpoint
  • func (r *RoundRobin) FindEndpointByUrl(url string) *WeightedEndpoint
  • func (r *RoundRobin) GetEndpoints() []*WeightedEndpoint
  • func (r *RoundRobin) NextEndpoint(req request.Request) (endpoint.Endpoint, error)
  • func (rr *RoundRobin) ObserveRequest(request.Request)
  • func (rr *RoundRobin) ObserveResponse(req request.Request, a request.Attempt)
  • func (rr *RoundRobin) ProcessRequest(request.Request) (*http.Response, error)
  • func (rr *RoundRobin) ProcessResponse(req request.Request, a request.Attempt)
  • func (r *RoundRobin) RemoveEndpoint(endpoint endpoint.Endpoint) error
• type SuggestedWeight
• type WeightedEndpoint
  • func (we *WeightedEndpoint) GetEffectiveWeight() int
  • func (we *WeightedEndpoint) GetId() string
  • func (we *WeightedEndpoint) GetMeter() metrics.FailRateMeter
  • func (we *WeightedEndpoint) GetOriginalEndpoint() endpoint.Endpoint
  • func (we *WeightedEndpoint) GetOriginalWeight() int
  • func (we *WeightedEndpoint) GetUrl() *url.URL
  • func (we *WeightedEndpoint) String() string
• type WeightedEndpoints
  • func (we WeightedEndpoints) Len() int
  • func (we WeightedEndpoints) Less(i, j int) bool
  • func (we WeightedEndpoints) Swap(i, j int)

Constants

const (
	// This is the maximum weight that handler will set for the endpoint
	FSMMaxWeight = 4096
	// Multiplier for the endpoint weight
	FSMGrowFactor = 16
)

Types

type EndpointOptions

type EndpointOptions struct {
	// Relative weight for the enpoint to other enpoints in the load balancer
	Weight int

	// Meter tracks the failure count and is used to do failover
	Meter metrics.FailRateMeter
}

Set additional parameters for the endpoint can be supplied when adding endpoint

type EndpointWeight

type EndpointWeight struct {
	Endpoint *WeightedEndpoint
	Weight   int
}

func (*EndpointWeight) GetEndpoint

func (ew *EndpointWeight) GetEndpoint() *WeightedEndpoint

func (*EndpointWeight) GetWeight

func (ew *EndpointWeight) GetWeight() int

func (*EndpointWeight) SetWeight

func (ew *EndpointWeight) SetWeight(w int)

type FSMHandler

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

This handler increases weights on endpoints that perform better than others it also rolls back to original weights if the endpoints have changed.

func NewFSMHandler

func NewFSMHandler() (*FSMHandler, error)

func NewFSMHandlerWithOptions

func NewFSMHandlerWithOptions(timeProvider timetools.TimeProvider) (*FSMHandler, error)

func (*FSMHandler) AdjustWeights

func (fsm *FSMHandler) AdjustWeights() ([]SuggestedWeight, error)

Called on every load balancer NextEndpoint call, returns the suggested weights on every call, can adjust weights if needed.

func (*FSMHandler) Init

func (fsm *FSMHandler) Init(endpoints []*WeightedEndpoint)

type FailureHandler

type FailureHandler interface {
	// Returns error if something bad happened, returns suggested weights
	AdjustWeights() ([]SuggestedWeight, error)
	// Initializes handler with current set of endpoints. Will be called
	// each time endpoints are added or removed from the load balancer
	// to give failure handler a chance to set it's itenral state
	Init(endpoints []*WeightedEndpoint)
}

type Options

type Options struct {
	// Control time in tests
	TimeProvider timetools.TimeProvider
	// Algorithm that reacts on the failures and can adjust weights
	FailureHandler FailureHandler
}

type RoundRobin

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

Dynamic weighted round robin load balancer.

func NewRoundRobin

func NewRoundRobin() (*RoundRobin, error)

func NewRoundRobinWithOptions

func NewRoundRobinWithOptions(o Options) (*RoundRobin, error)

func (*RoundRobin) AddEndpoint

func (rr *RoundRobin) AddEndpoint(endpoint endpoint.Endpoint) error

func (*RoundRobin) AddEndpointWithOptions

func (r *RoundRobin) AddEndpointWithOptions(endpoint endpoint.Endpoint, options EndpointOptions) error

In case if endpoint is already present in the load balancer, returns error

func (*RoundRobin) FindEndpointById

func (r *RoundRobin) FindEndpointById(id string) *WeightedEndpoint

func (*RoundRobin) FindEndpointByUrl

func (r *RoundRobin) FindEndpointByUrl(url string) *WeightedEndpoint

func (*RoundRobin) GetEndpoints

func (r *RoundRobin) GetEndpoints() []*WeightedEndpoint

func (*RoundRobin) NextEndpoint

func (r *RoundRobin) NextEndpoint(req request.Request) (endpoint.Endpoint, error)

func (*RoundRobin) ObserveRequest

func (rr *RoundRobin) ObserveRequest(request.Request)

func (*RoundRobin) ObserveResponse

func (rr *RoundRobin) ObserveResponse(req request.Request, a request.Attempt)

func (*RoundRobin) ProcessRequest

func (rr *RoundRobin) ProcessRequest(request.Request) (*http.Response, error)

func (*RoundRobin) ProcessResponse

func (rr *RoundRobin) ProcessResponse(req request.Request, a request.Attempt)

func (*RoundRobin) RemoveEndpoint

func (r *RoundRobin) RemoveEndpoint(endpoint endpoint.Endpoint) error

type SuggestedWeight

type SuggestedWeight interface {
	GetEndpoint() *WeightedEndpoint
	GetWeight() int
	SetWeight(int)
}

type WeightedEndpoint

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

WeightedEndpoint wraps the endpoint and adds support for weights and failure detection.

func (*WeightedEndpoint) GetEffectiveWeight

func (we *WeightedEndpoint) GetEffectiveWeight() int

func (*WeightedEndpoint) GetId

func (we *WeightedEndpoint) GetId() string

func (*WeightedEndpoint) GetMeter

func (we *WeightedEndpoint) GetMeter() metrics.FailRateMeter

func (*WeightedEndpoint) GetOriginalEndpoint

func (we *WeightedEndpoint) GetOriginalEndpoint() endpoint.Endpoint

func (*WeightedEndpoint) GetOriginalWeight

func (we *WeightedEndpoint) GetOriginalWeight() int

func (*WeightedEndpoint) GetUrl

func (we *WeightedEndpoint) GetUrl() *url.URL

func (*WeightedEndpoint) String

func (we *WeightedEndpoint) String() string

type WeightedEndpoints

type WeightedEndpoints []*WeightedEndpoint

func (WeightedEndpoints) Len

func (we WeightedEndpoints) Len() int

func (WeightedEndpoints) Less

func (we WeightedEndpoints) Less(i, j int) bool

func (WeightedEndpoints) Swap

func (we WeightedEndpoints) Swap(i, j int)