std::atomic_is_lock_free

template< class T >
bool atomic_is_lock_free( const volatile std::atomic<T>* obj );

template< class T >
bool atomic_is_lock_free( const std::atomic<T>* obj );

#define ATOMIC_BOOL_LOCK_FREE     /* unspecified */
#define ATOMIC_CHAR_LOCK_FREE     /* unspecified */
#define ATOMIC_CHAR16_T_LOCK_FREE /* unspecified */
#define ATOMIC_CHAR32_T_LOCK_FREE /* unspecified */
#define ATOMIC_WCHAR_T_LOCK_FREE  /* unspecified */
#define ATOMIC_SHORT_LOCK_FREE    /* unspecified */
#define ATOMIC_INT_LOCK_FREE      /* unspecified */
#define ATOMIC_LONG_LOCK_FREE     /* unspecified */
#define ATOMIC_LLONG_LOCK_FREE    /* unspecified */
#define ATOMIC_POINTER_LOCK_FREE  /* unspecified */

2) Expands to an integer constant expression with value

• ​0​ for the built-in atomic types that are never lock-free
• 1 for the built-in atomic types that are sometimes lock-free
• 2 for the built-in atomic types that are always lock-free.

Parameters

Return value

true if *obj is a lock-free atomic, false otherwise.

Exceptions

Notes

All atomic types except for std::atomic_flag may be implemented using mutexes or other locking operations, rather than using the lock-free atomic CPU instructions. Atomic types are also allowed to be sometimes lock-free, e.g. if only aligned memory accesses are naturally atomic on a given architecture, misaligned objects of the same type have to use locks.

Example

See also