[atomics.types.int] (original) (raw)

There are specializations of the atomicclass template for the integral typeschar,signed char,unsigned char,short,unsigned short,int,unsigned int,long,unsigned long,long long,unsigned long long,char8_t,char16_t,char32_t,wchar_t, and any other types needed by the typedefs in the header <cstdint> ([cstdint.syn]).

For each such type integral, the specializationatomic<integral> provides additional atomic operations appropriate to integral types.

namespace std { template<> struct atomic { using value_type = integral; using difference_type = value_type;

static constexpr bool is_always_lock_free = implementation-defined;
bool is_lock_free() const volatile noexcept;
bool is_lock_free() const noexcept;

constexpr atomic() noexcept;
constexpr atomic(integral) noexcept;
atomic(const atomic&) = delete;
atomic& operator=(const atomic&) = delete;
atomic& operator=(const atomic&) volatile = delete;

void store(integral, memory_order = memory_order::seq_cst) volatile noexcept;
void store(integral, memory_order = memory_order::seq_cst) noexcept;
integral operator=(integral) volatile noexcept;
integral operator=(integral) noexcept;
integral load(memory_order = memory_order::seq_cst) const volatile noexcept;
integral load(memory_order = memory_order::seq_cst) const noexcept;
operator integral() const volatile noexcept;
operator integral() const noexcept;

integral exchange(integral, memory_order = memory_order::seq_cst) volatile noexcept;
integral exchange(integral, memory_order = memory_order::seq_cst) noexcept;
bool compare_exchange_weak(integral&, integral,
                           memory_order, memory_order) volatile noexcept;
bool compare_exchange_weak(integral&, integral,
                           memory_order, memory_order) noexcept;
bool compare_exchange_strong(integral&, integral,
                             memory_order, memory_order) volatile noexcept;
bool compare_exchange_strong(integral&, integral,
                             memory_order, memory_order) noexcept;
bool compare_exchange_weak(integral&, integral,
                           memory_order = memory_order::seq_cst) volatile noexcept;
bool compare_exchange_weak(integral&, integral,
                           memory_order = memory_order::seq_cst) noexcept;
bool compare_exchange_strong(integral&, integral,
                             memory_order = memory_order::seq_cst) volatile noexcept;
bool compare_exchange_strong(integral&, integral,
                             memory_order = memory_order::seq_cst) noexcept;

integral fetch_add(integral, memory_order = memory_order::seq_cst) volatile noexcept;
integral fetch_add(integral, memory_order = memory_order::seq_cst) noexcept;
integral fetch_sub(integral, memory_order = memory_order::seq_cst) volatile noexcept;
integral fetch_sub(integral, memory_order = memory_order::seq_cst) noexcept;
integral fetch_and(integral, memory_order = memory_order::seq_cst) volatile noexcept;
integral fetch_and(integral, memory_order = memory_order::seq_cst) noexcept;
integral fetch_or(integral, memory_order = memory_order::seq_cst) volatile noexcept;
integral fetch_or(integral, memory_order = memory_order::seq_cst) noexcept;
integral fetch_xor(integral, memory_order = memory_order::seq_cst) volatile noexcept;
integral fetch_xor(integral, memory_order = memory_order::seq_cst) noexcept;

integral operator++(int) volatile noexcept;
integral operator++(int) noexcept;
integral operator--(int) volatile noexcept;
integral operator--(int) noexcept;
integral operator++() volatile noexcept;
integral operator++() noexcept;
integral operator--() volatile noexcept;
integral operator--() noexcept;
integral operator+=(integral) volatile noexcept;
integral operator+=(integral) noexcept;
integral operator-=(integral) volatile noexcept;
integral operator-=(integral) noexcept;
integral operator&=(integral) volatile noexcept;
integral operator&=(integral) noexcept;
integral operator|=(integral) volatile noexcept;
integral operator|=(integral) noexcept;
integral operator^=(integral) volatile noexcept;
integral operator^=(integral) noexcept;

void wait(integral, memory_order = memory_order::seq_cst) const volatile noexcept;
void wait(integral, memory_order = memory_order::seq_cst) const noexcept;
void notify_one() volatile noexcept;
void notify_one() noexcept;
void notify_all() volatile noexcept;
void notify_all() noexcept;

}; }

The atomic integral specializations are standard-layout structs.

They each have a trivial destructor.

Descriptions are provided below only for members that differ from the primary template.

The following operations perform arithmetic computations.

The key, operator, and computation correspondence is:

Table 144: Atomic arithmetic computations [tab:atomic.types.int.comp]

key	Op	Computation	key	Op	Computation
add	+	addition	sub	-	subtraction
or	\|	bitwise inclusive or	xor	^	bitwise exclusive or
and	&	bitwise and

Constraints:For the volatile overload of this function,is_always_lock_free is true.

Effects:Atomically replaces the value pointed to bythis with the result of the computation applied to the value pointed to by this and the given operand.

Memory is affected according to the value of order.

These operations are atomic read-modify-write operations ([intro.multithread]).

Returns:Atomically, the value pointed to by this immediately before the effects.

Remarks:For signed integer types, the result is as if the object value and parameters were converted to their corresponding unsigned types, the computation performed on those types, and the result converted back to the signed type.

[ Note

There are no undefined results arising from the computation.

— end note

]

Constraints:For the volatile overload of this function,is_always_lock_free is true.

Effects:Equivalent to: return fetch_key(operand) op operand;