52 lines
1.5 KiB
Go
52 lines
1.5 KiB
Go
/*
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The Selector package provides a way to algorithmically filter and return
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nodes required by the client or any other system. Selector's implemented
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by Micro build on the registry but it's of optional use. One could
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provide a static Selector that has a fixed pool.
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*/
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package selector
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import (
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"errors"
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"github.com/micro/go-micro/registry"
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)
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// Selector builds on the registry as a mechanism to pick nodes
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// and mark their status. This allows host pools and other things
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// to be built using various algorithms.
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type Selector interface {
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Init(opts ...Option) error
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Options() Options
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// Select returns a function which should return the next node
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Select(service string, opts ...SelectOption) (Next, error)
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// Mark sets the success/error against a node
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Mark(service string, node *registry.Node, err error)
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// Reset returns state back to zero for a service
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Reset(service string)
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// Close renders the selector unusable
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Close() error
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// Name of the selector
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String() string
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}
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// Next is a function that returns the next node
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// based on the selector's strategy
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type Next func() (*registry.Node, error)
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// Filter is used to filter a service during the selection process
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type Filter func([]*registry.Service) []*registry.Service
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// Strategy is a selection strategy e.g random, round robin
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type Strategy func([]*registry.Service) Next
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var (
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DefaultSelector = newDefaultSelector()
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ErrNotFound = errors.New("not found")
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ErrNoneAvailable = errors.New("none available")
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)
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func NewSelector(opts ...Option) Selector {
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return newDefaultSelector(opts...)
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}
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