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std::atomic_is_lock_free, ATOMIC_xxx_LOCK_FREE

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< cpp‎ | atomic
Revision as of 11:34, 17 August 2013 by P12 (Talk | contribs)

Defined in header <atomic>
(1)
template< class Atomic >
bool atomic_is_lock_free( const volatile Atomic* obj )
(since C++11)
template< class Atomic >
bool atomic_is_lock_free( const Atomic* obj )
(since C++11)
#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) (since C++11)
1) Determines if the atomic object pointed to by obj is implemented lock-free, as if by calling obj->is_lock_free()
2) Expands to an integer constant expression with value 0 for the built-in atomic types that are never lock-free, to 1 for the built-in atomic types that are sometimes lock-free, and to 2 for the built-in atomic types that are always lock-free.

Contents

Parameters

obj - pointer to the atomic object to examine

Return value

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

Exceptions

noexcept specification:  
noexcept
  

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. If the type is sometimes lock-free, then the function (1) or its member function equivalent has to be used to determine if the particular instance is lock-free.

Example

See also

checks if the atomic object is lock-free
(public member function of std::atomic) [edit]
specializes atomic operations for std::shared_ptr
(function template)
the lock-free boolean atomic type
(class) [edit]