roundrobin

Documentation

Overview

package roundrobin implements dynamic weighted round robin load balancer http handler

Index

• Constants
• type LBOption
  • func ErrorHandler(h utils.ErrorHandler) LBOption
• type Meter
• type NewMeterFn
• type Rebalancer
  • func NewRebalancer(handler balancerHandler, opts ...RebalancerOption) (*Rebalancer, error)
  • func (rb *Rebalancer) RemoveServer(u *url.URL) error
  • func (rb *Rebalancer) ServeHTTP(w http.ResponseWriter, req *http.Request)
  • func (rb *Rebalancer) Servers() []*url.URL
  • func (rb *Rebalancer) UpsertServer(u *url.URL, options ...ServerOption) error
  • func (rb *Rebalancer) Wrap(next balancerHandler) error
• type RebalancerOption
  • func RebalancerBackoff(d time.Duration) RebalancerOption
  • func RebalancerClock(clock timetools.TimeProvider) RebalancerOption
  • func RebalancerErrorHandler(h utils.ErrorHandler) RebalancerOption
  • func RebalancerLogger(log utils.Logger) RebalancerOption
  • func RebalancerMeter(newMeter NewMeterFn) RebalancerOption
• type RoundRobin
  • func New(next http.Handler, opts ...LBOption) (*RoundRobin, error)
  • func (r *RoundRobin) Next() http.Handler
  • func (r *RoundRobin) NextServer() (*url.URL, error)
  • func (r *RoundRobin) RemoveServer(u *url.URL) error
  • func (r *RoundRobin) ServeHTTP(w http.ResponseWriter, req *http.Request)
  • func (rr *RoundRobin) ServerWeight(u *url.URL) (int, bool)
  • func (rr *RoundRobin) Servers() []*url.URL
  • func (rr *RoundRobin) UpsertServer(u *url.URL, options ...ServerOption) error
• type ServerOption
  • func Weight(w int) ServerOption

Constants

const (
	// This is the maximum weight that handler will set for the server
	FSMMaxWeight = 4096
	// Multiplier for the server weight
	FSMGrowFactor = 4
)

Types

type LBOption

type LBOption func(*RoundRobin) error

LBOption provides options for load balancer

func ErrorHandler

func ErrorHandler(h utils.ErrorHandler) LBOption

ErrorHandler is a functional argument that sets error handler of the server

type Meter

type Meter interface {
	Rating() float64
	Record(int, time.Duration)
	IsReady() bool
}

Meter measures server peformance and returns it's relative value via rating

type NewMeterFn

type NewMeterFn func() (Meter, error)

type Rebalancer

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

Rebalancer increases weights on servers that perform better than others. It also rolls back to original weights if the servers have changed. It is designed as a wrapper on top of the roundrobin.

func NewRebalancer

func NewRebalancer(handler balancerHandler, opts ...RebalancerOption) (*Rebalancer, error)

func (*Rebalancer) RemoveServer

func (rb *Rebalancer) RemoveServer(u *url.URL) error

func (*Rebalancer) ServeHTTP

func (rb *Rebalancer) ServeHTTP(w http.ResponseWriter, req *http.Request)

func (*Rebalancer) Servers

func (rb *Rebalancer) Servers() []*url.URL

func (*Rebalancer) UpsertServer

func (rb *Rebalancer) UpsertServer(u *url.URL, options ...ServerOption) error

func (*Rebalancer) Wrap

func (rb *Rebalancer) Wrap(next balancerHandler) error

type RebalancerOption

type RebalancerOption func(*Rebalancer) error

RebalancerOption - functional option setter for rebalancer

func RebalancerBackoff

func RebalancerBackoff(d time.Duration) RebalancerOption

func RebalancerClock

func RebalancerClock(clock timetools.TimeProvider) RebalancerOption

func RebalancerErrorHandler

func RebalancerErrorHandler(h utils.ErrorHandler) RebalancerOption

RebalancerErrorHandler is a functional argument that sets error handler of the server

func RebalancerLogger

func RebalancerLogger(log utils.Logger) RebalancerOption

func RebalancerMeter

func RebalancerMeter(newMeter NewMeterFn) RebalancerOption

type RoundRobin

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

func New

func New(next http.Handler, opts ...LBOption) (*RoundRobin, error)

func (*RoundRobin) Next

func (r *RoundRobin) Next() http.Handler

func (*RoundRobin) NextServer

func (r *RoundRobin) NextServer() (*url.URL, error)

func (*RoundRobin) RemoveServer

func (r *RoundRobin) RemoveServer(u *url.URL) error

func (*RoundRobin) ServeHTTP

func (r *RoundRobin) ServeHTTP(w http.ResponseWriter, req *http.Request)

func (*RoundRobin) ServerWeight

func (rr *RoundRobin) ServerWeight(u *url.URL) (int, bool)

func (*RoundRobin) Servers

func (rr *RoundRobin) Servers() []*url.URL

func (*RoundRobin) UpsertServer

func (rr *RoundRobin) UpsertServer(u *url.URL, options ...ServerOption) error

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

type ServerOption

type ServerOption func(*server) error

ServerOption provides various options for server, e.g. weight

func Weight

func Weight(w int) ServerOption

Weight is an optional functional argument that sets weight of the server