balancer

Documentation

Overview

Package balancer implements tiered pooling behavior across resolved backends.

Index

• type Backend
  • func (b *Backend) Addr() net.Addr
  • func (b *Backend) AssignTier(latency time.Duration, tier int)
  • func (b *Backend) Disable()
  • func (b *Backend) ForcePromotionAfter() time.Duration
  • func (b *Backend) MarshalYAML() (interface{}, error)
  • func (b *Backend) MaxLoad() int
  • func (b *Backend) String() string
  • func (b *Backend) Tier() int
• type BackendToken
  • func (t *BackendToken) Balancer() *Balancer
  • func (t *BackendToken) Entry() *Backend
• type Balancer
  • func (b *Balancer) Config() *config.BackendPool
  • func (b *Balancer) Configure(ctx context.Context, cfg config.BackendPool, tolerateErrors bool) error
  • func (b *Balancer) IsOverloaded(backend *Backend) bool
  • func (b *Balancer) MarshalYAML() (interface{}, error)
  • func (b *Balancer) Pick() *BackendToken
  • func (b *Balancer) Rebalance(context.Context)
  • func (b *Balancer) String() string
  • func (b *Balancer) Wait(ctx context.Context) (*BackendToken, error)
• type Key

Types

type Backend

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

A Backend creates connections to one specific backend (e.g. a TCP connection to a specific IP address).

func (*Backend) Addr

func (b *Backend) Addr() net.Addr

Addr returns the Backend address.

func (*Backend) AssignTier

func (b *Backend) AssignTier(latency time.Duration, tier int)

AssignTier (re-)assigns a Backend to a tier based on a latency metric.

func (*Backend) Disable

func (b *Backend) Disable()

Disable takes the Backend out of rotation for the configured duration.

func (*Backend) ForcePromotionAfter

func (b *Backend) ForcePromotionAfter() time.Duration

ForcePromotionAfter indicates that clients should be forcefully disconnected from this backend if a better choice is available.

func (*Backend) MarshalYAML

func (b *Backend) MarshalYAML() (interface{}, error)

MarshalYAML implements yaml.Marshaler interfare and provides a diagnostic view of the Backend.

func (*Backend) MaxLoad

func (b *Backend) MaxLoad() int

MaxLoad implements pool.Entry and reflects the number of concurrent calls to Dial().

func (*Backend) String

func (b *Backend) String() string

func (*Backend) Tier

func (b *Backend) Tier() int

Tier implements pool.Entry and reflects the overall priority of the Backend.

type BackendToken

type BackendToken struct {
	*pool.Token
	// contains filtered or unexported fields
}

BackendToken is a typesafe wrapper around pool.Token.

func (*BackendToken) Balancer

func (t *BackendToken) Balancer() *Balancer

Balancer returns the owner.

func (*BackendToken) Entry

func (t *BackendToken) Entry() *Backend

Entry provides type safety around Token.Entry.

type Balancer

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

A Balancer implements pooling behavior across resolved backends.

func (*Balancer) Config

func (b *Balancer) Config() *config.BackendPool

Config returns the currently-active configuration.

func (*Balancer) Configure

func (b *Balancer) Configure(ctx context.Context, cfg config.BackendPool, tolerateErrors bool) error

Configure will initialize or update the pool configuration and attempt to resolve the targets.

func (*Balancer) IsOverloaded

func (b *Balancer) IsOverloaded(backend *Backend) bool

IsOverloaded returns true if the given backend should be considered to be in an overload situation (e.g. when draining).

func (*Balancer) MarshalYAML

func (b *Balancer) MarshalYAML() (interface{}, error)

MarshalYAML implements yaml.Marshaler and provides a diagnostic view of the Balancer.

func (*Balancer) Pick

func (b *Balancer) Pick() *BackendToken

Pick returns the next best choice from the pool or nil if one is not available.

func (*Balancer) Rebalance

func (b *Balancer) Rebalance(context.Context)

Rebalance will rebalance the underlying pool by assigning backends to latency buckets.

func (*Balancer) String

func (b *Balancer) String() string

func (*Balancer) Wait

func (b *Balancer) Wait(ctx context.Context) (*BackendToken, error)

Wait blocks until a Backend can be returned or the context is canceled.

type Key

type Key int

Key is a typesafe Context key.

const (
	// KeyBackendToken retrieves a *BackendToken from a Context.
	KeyBackendToken Key = iota + 1
)