balancer

Documentation

Index

• Constants
• Variables
• type ConsistentHashringBalancer
  • func (b *ConsistentHashringBalancer) Close()
  • func (b *ConsistentHashringBalancer) ResolverError(err error)
  • func (b *ConsistentHashringBalancer) UpdateClientConnState(s balancer.ClientConnState) error
  • func (b *ConsistentHashringBalancer) UpdateSubConnState(sc balancer.SubConn, state balancer.SubConnState)
• type ConsistentHashringBalancerConfig
  • func (c *ConsistentHashringBalancerConfig) MustToServiceConfigJSON() string
  • func (c *ConsistentHashringBalancerConfig) ToServiceConfigJSON() (string, error)
• type ConsistentHashringBuilder
  • func NewConsistentHashringBuilder(hasher consistent.HasherFunc) *ConsistentHashringBuilder
  • func (b *ConsistentHashringBuilder) Build(cc balancer.ClientConn, _ balancer.BuildOptions) balancer.Balancer
  • func (b *ConsistentHashringBuilder) Name() string
  • func (b *ConsistentHashringBuilder) ParseConfig(js json.RawMessage) (serviceconfig.LoadBalancingConfig, error)

Constants

const (
	// BalancerName is the name of consistent-hashring balancer.
	BalancerName = "consistent-hashring"

	// CtxKey is the key for the grpc request's context.Context which points to
	// the key to hash for the request. The value it points to must be []byte
	CtxKey ctxKey = "requestKey"
)

Variables

var DefaultBalancerServiceConfigJSON = defaultBalancerServiceConfig.MustToServiceConfigJSON()

DefaultBalancerServiceConfigJSON is a grpc Service Config JSON with the defaults for the ConsstentHashringBalancer configured.

Types

type ConsistentHashringBalancer

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

ConsistentHashringBalancer implements balancer.Balancer and uses a consistent hashring to pick a backend for a request.

func (*ConsistentHashringBalancer) Close

func (b *ConsistentHashringBalancer) Close()

Close is a no-op because base balancer doesn't have internal state to clean up, and it doesn't need to call RemoveSubConn for the SubConns.

func (*ConsistentHashringBalancer) ResolverError

func (b *ConsistentHashringBalancer) ResolverError(err error)

ResolverError satisfies balancer.Balancer and is called when there is a an error in the resolver.

func (*ConsistentHashringBalancer) UpdateClientConnState

func (b *ConsistentHashringBalancer) UpdateClientConnState(s balancer.ClientConnState) error

UpdateClientConnState satisfies balancer.Balancer and is called when there are changes in the Address set or Service Config that the balancer may want to react to. In this case, the hashring is updated and a new picker using that hashring is generated.

func (*ConsistentHashringBalancer) UpdateSubConnState

func (b *ConsistentHashringBalancer) UpdateSubConnState(sc balancer.SubConn, state balancer.SubConnState)

UpdateSubConnState satisfies balancer.Balancer and is called when there is a change in a subconnection state. Subconnection state can affect the overall state of the balancer. This also attempts to reconnect any idle connections.

type ConsistentHashringBalancerConfig

type ConsistentHashringBalancerConfig struct {
	serviceconfig.LoadBalancingConfig `json:"-"`
	ReplicationFactor                 uint16 `json:"replicationFactor,omitempty"`
	Spread                            uint8  `json:"spread,omitempty"`
}

ConsistentHashringBalancerConfig supports common settings for the balancer. It should be converted to json with ToServiceConfigJSON or MustToServiceConfigJSON and passed to the grpc.WithDefaultServiceConfig option on grpc.Dial.

func (*ConsistentHashringBalancerConfig) MustToServiceConfigJSON

func (c *ConsistentHashringBalancerConfig) MustToServiceConfigJSON() string

MustToServiceConfigJSON calls ToServiceConfigJSON but panics if there is an error.

func (*ConsistentHashringBalancerConfig) ToServiceConfigJSON

func (c *ConsistentHashringBalancerConfig) ToServiceConfigJSON() (string, error)

ToServiceConfigJSON converts the config into the standard grpc Service Config json format.

type ConsistentHashringBuilder

type ConsistentHashringBuilder struct {
	sync.Mutex
	// contains filtered or unexported fields
}

ConsistentHashringBuilder stamps out new ConsistentHashringBalancer when requested by grpc.

func NewConsistentHashringBuilder

func NewConsistentHashringBuilder(hasher consistent.HasherFunc) *ConsistentHashringBuilder

NewConsistentHashringBuilder creates a new balancer.Builder that will create a consistent hashring balancer. Before making a connection, register it with grpc with: `balancer.Register(consistent.NewConsistentHashringBuilder(hasher))`

func (*ConsistentHashringBuilder) Build

func (b *ConsistentHashringBuilder) Build(cc balancer.ClientConn, _ balancer.BuildOptions) balancer.Balancer

Build satisfies balancer.Builder and returns a new ConsistentHashringBalancer.

func (*ConsistentHashringBuilder) Name

func (b *ConsistentHashringBuilder) Name() string

Name satisfies balancer.Builder and returns the name of the balancer for use in Service Config files.

func (*ConsistentHashringBuilder) ParseConfig

func (b *ConsistentHashringBuilder) ParseConfig(js json.RawMessage) (serviceconfig.LoadBalancingConfig, error)

ParseConfig satisfies balancer.ConfigParser and is used to parse new Service Config json. The results are stored on the builder so that subsequently built Balancers use the config.