跨平台原子操作

最新推荐文章于 2025-11-12 14:22:20 发布

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#这是gloox里的原子操作代码封装 #其实本人并不喜欢这种封装方式 #更倾向于不同平台单独封装类 #而不是几个#if #else

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本文介绍了一个名为AtomicRefCount的类的实现细节，该类用于提供跨平台的原子操作功能，如递增、递减和重置计数器值。通过使用特定于平台的原子操作或者互斥锁作为备选方案，确保了线程安全。

class AtomicRefCount
{
public:
AtomicRefCount();

int increment();
int decrement();
void reset();

private:

AtomicRefCount& operator=( const AtomicRefCount& );

volatile int m_count;
Mutex m_lock;

};

#include "atomicrefcount.h"

#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
# include <windows.h>
#elif defined( __APPLE__ )
# include <libkern/OSAtomic.h>
#elif defined( HAVE_GCC_ATOMIC_BUILTINS )
// Use intrinsic functions - no #include required.
#else
# include "mutexguard.h"
#endif

#ifdef _WIN32_WCE
# include <winbase.h>
#endif

AtomicRefCount::AtomicRefCount()
: m_count( 0 )
{
}

int AtomicRefCount::increment()
{
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
return (int) ::InterlockedIncrement( (volatile LONG*)&m_count );
#elif defined( __APPLE__ )
return (int) OSAtomicIncrement32Barrier( (volatile int32_t*)&m_count );
#elif defined( HAVE_GCC_ATOMIC_BUILTINS )
// Use the gcc intrinsic for atomic increment if supported.
return (int) __sync_add_and_fetch( &m_count, 1 );
#else
// Fallback to using a lock
MutexGuard m( m_lock );
return ++m_count;
#endif
}

int AtomicRefCount::decrement()
{
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
return (int) ::InterlockedDecrement( (volatile LONG*)&m_count );
#elif defined( __APPLE__ )
return (int) OSAtomicDecrement32Barrier( (volatile int32_t*)&m_count );
#elif defined( HAVE_GCC_ATOMIC_BUILTINS )
// Use the gcc intrinsic for atomic decrement if supported.
return (int) __sync_sub_and_fetch( &m_count, 1 );
#else
// Fallback to using a lock
MutexGuard m( m_lock );
return --m_count;
#endif
}

void AtomicRefCount::reset()
{
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
::InterlockedExchange( (volatile LONG*)&m_count, (volatile LONG)0 );
#elif defined( __APPLE__ )
OSAtomicAnd32Barrier( (int32_t)0, (volatile int32_t*)&m_count );
#elif defined( HAVE_GCC_ATOMIC_BUILTINS )
// Use the gcc intrinsic for atomic decrement if supported.
__sync_fetch_and_and( &m_count, 0 );
#else
// Fallback to using a lock
MutexGuard m( m_lock );
m_count = 0;
#endif
}