非线程安全的单例模式

type Singleton struct {
   
}
var instance *Singleton
func GetInstance() *Singleton {
   
	if instance == nil {
   
		instance = &Singleton{
   }
	}
	return instance
}

基于互斥锁的单例模式

type Singleton struct {
   
}
var (
	instance *Singleton
	mu sync.Mutex
)
func GetInstance() *Singleton