Package base defines a balancer base that can be used to build balancers with different picking algorithms.

The base balancer creates a new SubConn for each resolved address. The provided picker will only be notified about READY SubConns.

This package is the base of round_robin balancer, its purpose is to be used to build round_robin like balancers with complex picking algorithms. Balancers with more complicated logic should try to implement a balancer builder from scratch.

All APIs in this package are experimental.



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var NewErrPickerV2 = NewErrPicker

NewErrPickerV2 is temporarily defined for backward compatibility reasons.

Deprecated: use NewErrPicker instead.


func NewBalancerBuilder

func NewBalancerBuilder(name string, pb PickerBuilder, config Config) balancer.Builder

NewBalancerBuilder returns a base balancer builder configured by the provided config.

func NewErrPicker

func NewErrPicker(err error) balancer.Picker

NewErrPicker returns a Picker that always returns err on Pick().


type Config

type Config struct {
	// HealthCheck indicates whether health checking should be enabled for this specific balancer.
	HealthCheck bool

Config contains the config info about the base balancer builder.

type PickerBuildInfo

type PickerBuildInfo struct {
	// ReadySCs is a map from all ready SubConns to the Addresses used to
	// create them.
	ReadySCs map[balancer.SubConn]SubConnInfo

PickerBuildInfo contains information needed by the picker builder to construct a picker.

type PickerBuilder

type PickerBuilder interface {
	// Build returns a picker that will be used by gRPC to pick a SubConn.
	Build(info PickerBuildInfo) balancer.Picker

PickerBuilder creates balancer.Picker.

type SubConnInfo

type SubConnInfo struct {
	Address resolver.Address // the address used to create this SubConn

SubConnInfo contains information about a SubConn created by the base balancer.