73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
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package etcd
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import (
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"github.com/go-kit/kit/endpoint"
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"github.com/go-kit/kit/log"
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"github.com/go-kit/kit/sd"
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"github.com/go-kit/kit/sd/cache"
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)
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// Subscriber yield endpoints stored in a certain etcd keyspace. Any kind of
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// change in that keyspace is watched and will update the Subscriber endpoints.
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type Subscriber struct {
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client Client
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prefix string
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cache *cache.Cache
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logger log.Logger
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quitc chan struct{}
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}
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var _ sd.Subscriber = &Subscriber{}
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// NewSubscriber returns an etcd subscriber. It will start watching the given
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// prefix for changes, and update the endpoints.
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func NewSubscriber(c Client, prefix string, factory sd.Factory, logger log.Logger) (*Subscriber, error) {
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s := &Subscriber{
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client: c,
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prefix: prefix,
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cache: cache.New(factory, logger),
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logger: logger,
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quitc: make(chan struct{}),
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}
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instances, err := s.client.GetEntries(s.prefix)
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if err == nil {
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logger.Log("prefix", s.prefix, "instances", len(instances))
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} else {
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logger.Log("prefix", s.prefix, "err", err)
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}
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s.cache.Update(instances)
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go s.loop()
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return s, nil
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}
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func (s *Subscriber) loop() {
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ch := make(chan struct{})
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go s.client.WatchPrefix(s.prefix, ch)
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for {
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select {
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case <-ch:
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instances, err := s.client.GetEntries(s.prefix)
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if err != nil {
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s.logger.Log("msg", "failed to retrieve entries", "err", err)
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continue
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}
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s.cache.Update(instances)
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case <-s.quitc:
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return
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}
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}
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}
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// Endpoints implements the Subscriber interface.
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func (s *Subscriber) Endpoints() ([]endpoint.Endpoint, error) {
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return s.cache.Endpoints(), nil
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}
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// Stop terminates the Subscriber.
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func (s *Subscriber) Stop() {
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close(s.quitc)
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}
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