多平台原子增量

Question

Until std::atomic is available, what is the multiplatform (windows & linux) way of atomically increment a variable ?

I am currently use boost::detail::atomic_count but it's in boost::detail namespace and I don't know if it's safe to use.

Answer 1

A multiplatform , but compiler specific way is to use GCC's __sync_fetch_and_add .

Or define such a function yourself with a bit of conditional compilation:

#ifdef __GNUC__
#define atomic_inc(ptr) __sync_fetch_and_add ((ptr), 1)
#elif defined (_WIN32)
#define atomic_inc(ptr) InterlockedIncrement ((ptr))
#else
#error "Need some more porting work here"
#endif

Answer 2

Use InterlockedExchangeAdd instead of InterlockedIncrement - it full analogue, with __sync_fetch_and_add ;

#ifdef __GNUC__
#define atomic_inc(ptr) __sync_fetch_and_add ((ptr), 1)
#elif defined (_WIN32)
#define atomic_inc(ptr) InterlockedExchangeAdd ((ptr), 1)
#else
#error "Need some more porting work here"
#endif