原子操作

针对整数数据类型（int32、uint32、int64、uint64）我们还可以使用原子操作来保证并发安全，通常直接使用原子操作比使用锁操作效率更高。Go语言中原子操作由内置的标准库sync/atomic提供。

atomic包

 

方法	解释
func LoadInt32(addr *int32) (val int32) func LoadInt64(addr *int64) (val int64) func LoadUint32(addr *uint32) (val uint32) func LoadUint64(addr *uint64) (val uint64) func LoadUintptr(addr *uintptr) (val uintptr) func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)	读取操作
func StoreInt32(addr *int32, val int32) func StoreInt64(addr *int64, val int64) func StoreUint32(addr *uint32, val uint32) func StoreUint64(addr *uint64, val uint64) func StoreUintptr(addr *uintptr, val uintptr) func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer)	写入操作
func AddInt32(addr *int32, delta int32) (new int32) func AddInt64(addr *int64, delta int64) (new int64) func AddUint32(addr *uint32, delta uint32) (new uint32) func AddUint64(addr *uint64, delta uint64) (new uint64) func AddUintptr(addr *uintptr, delta uintptr) (new uintptr)	修改操作
func SwapInt32(addr *int32, new int32) (old int32) func SwapInt64(addr *int64, new int64) (old int64) func SwapUint32(addr *uint32, new uint32) (old uint32) func SwapUint64(addr *uint64, new uint64) (old uint64) func SwapUintptr(addr *uintptr, new uintptr) (old uintptr) func SwapPointer(addr *unsafe.Pointer, new unsafe.Pointer) (old unsafe.Pointer)	交换操作
func CompareAndSwapInt32(addr *int32, old, new int32) (swapped bool) func CompareAndSwapInt64(addr *int64, old, new int64) (swapped bool) func CompareAndSwapUint32(addr *uint32, old, new uint32) (swapped bool) func CompareAndSwapUint64(addr *uint64, old, new uint64) (swapped bool) func CompareAndSwapUintptr(addr *uintptr, old, new uintptr) (swapped bool) func CompareAndSwapPointer(addr *unsafe.Pointer, old, new unsafe.Pointer) (swapped bool)	比较并交换操作

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package main   import (     "fmt"     "sync"     "sync/atomic"     "time" )   type Counter interface {     Inc()     Load() int64 }   // 普通版 type CommonCounter struct {     counter int64 }   func (c CommonCounter) Inc() {     c.counter++ }   func (c CommonCounter) Load() int64 {     return c.counter }   // 互斥锁版 type MutexCounter struct {     counter int64     lock    sync.Mutex }   func (m *MutexCounter) Inc() {     m.lock.Lock()     defer m.lock.Unlock()     m.counter++ }   func (m *MutexCounter) Load() int64 {     m.lock.Lock()     defer m.lock.Unlock()     return m.counter }   // 原子操作版 type AtomicCounter struct {     counter int64 }   func (a *AtomicCounter) Inc() {     atomic.AddInt64(&a.counter, 1) }   func (a *AtomicCounter) Load() int64 {     return atomic.LoadInt64(&a.counter) }   func test(c Counter) {     var wg sync.WaitGroup     start := time.Now()     for i := 0; i < 1000; i++ {         wg.Add(1)         go func() {             c.Inc()             wg.Done()         }()     }     wg.Wait()     end := time.Now()     fmt.Println(c.Load(), end.Sub(start)) }   func main() {     c1 := CommonCounter{} // 非并发安全     test(c1)     c2 := MutexCounter{} // 使用互斥锁实现并发安全     test(&c2)     c3 := AtomicCounter{} // 并发安全且比互斥锁效率更高     test(&c3) }

　　atomic包提供了底层的原子级内存操作，对于同步算法的实现很有用。这些函数必须谨慎地保证正确使用。除了某些特殊的底层应用，使用通道或者 sync 包的函数/类型实现同步更好。

参考：Go语言基础之并发 | 李文周的博客 (liwenzhou.com)