在线配置热加载配置 go-kratos.dev 监听key 通过atomic.Value支持自动热加载

paladin https://v1.go-kratos.dev/#/config-paladin

example Service（在线配置热加载配置）

# service.go
type Service struct {
    ac *paladin.Map
}

func New() *Service {
    // paladin.Map 通过atomic.Value支持自动热加载
    var ac = new(paladin.TOML)
    if err := paladin.Watch("application.toml", ac); err != nil {
        panic(err)
    }
    s := &Service{
        ac: ac,
    }
    return s
}

func (s *Service) Test() {
    sw, err := s.ac.Get("switch").Bool()
    if err != nil {
        // TODO
    }

    // or use default value
    sw := paladin.Bool(s.ac.Get("switch"), false)
}

// EventType is config event.
type EventType int
// Event is watch event.
type Event struct {
   Event EventType
   Key   string
   Value string
}
// Watcher is config watcher.
type Watcher interface {
   WatchEvent(context.Context, ...string) <-chan Event
   Close() error
}

// Watch watch on a key. The configuration implements the setter interface, which is invoked when the configuration changes.
func Watch(key string, s Setter) error {
   v := DefaultClient.Get(key)
   str, err := v.Raw()
   if err != nil {
      return err
   }
   if err := s.Set(str); err != nil {
      return err
   }
   go func() {
      for event := range WatchEvent(context.Background(), key) {
         s.Set(event.Value)
      }
   }()
   return nil
}
// WatchEvent watch on multi keys. Events are returned when the configuration changes.
func WatchEvent(ctx context.Context, keys ...string) <-chan Event {
   return DefaultClient.WatchEvent(ctx, keys...)
}
// Get return value by key.
func Get(key string) *Value {
   return DefaultClient.Get(key)
}
// GetAll return all config map.
func GetAll() *Map {
   return DefaultClient.GetAll()
}
// Keys return values key.
func Keys() []string {
   return DefaultClient.GetAll().Keys()
}
// Close close watcher.
func Close() error {
   return DefaultClient.Close()
}