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

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()      

}