gitee.com/liuxuezhan/go-micro-v1.18.0@v1.0.0/client/selector/selector.go (about)

     1  // Package selector is a way to pick a list of service nodes
     2  package selector
     3  
     4  import (
     5  	"errors"
     6  
     7  	"gitee.com/liuxuezhan/go-micro-v1.18.0/registry"
     8  )
     9  
    10  // Selector builds on the registry as a mechanism to pick nodes
    11  // and mark their status. This allows host pools and other things
    12  // to be built using various algorithms.
    13  type Selector interface {
    14  	Init(opts ...Option) error
    15  	Options() Options
    16  	// Select returns a function which should return the next node
    17  	Select(service string, opts ...SelectOption) (Next, error)
    18  	// Mark sets the success/error against a node
    19  	Mark(service string, node *registry.Node, err error)
    20  	// Reset returns state back to zero for a service
    21  	Reset(service string)
    22  	// Close renders the selector unusable
    23  	Close() error
    24  	// Name of the selector
    25  	String() string
    26  }
    27  
    28  // Next is a function that returns the next node
    29  // based on the selector's strategy
    30  type Next func() (*registry.Node, error)
    31  
    32  // Filter is used to filter a service during the selection process
    33  type Filter func([]*registry.Service) []*registry.Service
    34  
    35  // Strategy is a selection strategy e.g random, round robin
    36  type Strategy func([]*registry.Service) Next
    37  
    38  var (
    39  	DefaultSelector = NewSelector()
    40  
    41  	ErrNotFound      = errors.New("not found")
    42  	ErrNoneAvailable = errors.New("none available")
    43  )