base/model/set.go代码优化

[laijinhang]

base/model/set.go

// Len returns the number of items in a set.
func (s *Set) Len() int {
	return len(s.List())
}

改成下面效率会更高

// Len returns the number of items in a set.
func (s *Set) Len() int {
	s.RLock()
	defer s.RUnlock()
	return len(s.m)
}

[dk-lockdown]

you can fix it