Go语言实现单例模式的多种方法

package main
 
import (
	"fmt"
	"sync"
)
 
var wg sync.WaitGroup
 
// Singleton 结构体定义
type Singleton struct{}
 
var instance *Singleton
var once sync.Once
 
// GetInstance 返回全局唯一的实例
func GetInstance() *Singleton {
	once.Do(func() {
		instance = &Singleton{}
	})
	return instance
}
 
func main() {
	// 获取单例实例并打印内存地址
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(index int) {
			defer wg.Done()
			s1 := GetInstance()
			fmt.Printf("index %d, memory address: %p\n", index, s1)
		}(i)
	}
	wg.Wait()
}

package main
 
import (
	"fmt"
	"sync"
)
 
var wg sync.WaitGroup
 
// Singleton 结构体定义
type Singleton struct{}
 
var instance *Singleton
var lock sync.Mutex
 
func GetInstance() *Singleton {
	if instance == nil {
		lock.Lock()
		defer lock.Unlock()
		if instance == nil {
			instance = &Singleton{}
		}
	}
	return instance
}
 
func main() {
	// 获取单例实例并打印内存地址
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(index int) {
			defer wg.Done()
			s1 := GetInstance()
			fmt.Printf("index %d, memory address: %p\n", index, s1)
		}(i)
	}
	wg.Wait()
}

package main
 
import (
	"fmt"
	"sync"
	"sync/atomic"
	"unsafe"
)
 
var wg sync.WaitGroup
 
// Singleton 结构体定义
type Singleton struct{}
 
var instance unsafe.Pointer
 
func GetInstance() *Singleton {
	// 使用原子操作获取实例
	if atomic.LoadPointer(&instance) == nil {
		newInstance := &Singleton{}
		atomic.StorePointer(&instance, unsafe.Pointer(newInstance))
	}
	return (*Singleton)(atomic.LoadPointer(&instance))
}
 
func main() {
	// 获取单例实例并打印内存地址
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(index int) {
			defer wg.Done()
			s1 := GetInstance()
			fmt.Printf("index %d, memory address: %p\n", index, s1)
		}(i)
	}
	wg.Wait()
}