atomic Structure

Article
01/02/2018

The latest version of this topic can be found at atomic Structure.

Describes an object that performs atomic operations on a stored value of type Ty.

Syntax

template <class Ty>
struct atomic;

Members

Public Constructors

Name	Description
atomic::atomic Constructor	Constructs an atomic object.

Public Operators

Name	Description
atomic::operator Ty Operator	Reads and returns the stored value. (atomic::load Method)
atomic::operator= Operator	Uses a specified value to replace the stored value. (atomic::store Method)

atomic::operator++ Operator	Increments the stored value. Used only by integral and pointer specializations.
atomic::operator+= Operator	Adds a specified value to the stored value. Used only by integral and pointer specializations.
atomic::operator-- Operator	Decrements the stored value. Used only by integral and pointer specializations.
atomic::operator-= Operator	Subtracts a specified value from the stored value. Used only by integral and pointer specializations.
atomic::operator&= Operator	Performs a bitwise `and` on a specified value and the stored value. Used only by integral specializations.
atomic::operator\|= Operator	Performs a bitwise `or` on a specified value and the stored value. Used only by integral specializations.
atomic::operator^= Operator	Performs a bitwise `exclusive or` on a specified value and the stored value. Used only by integral specializations.

Public Methods

Name	Description
atomic::compare_exchange_strong Method	Performs an `atomic_compare_and_exchange` operation on `this` and returns the result.
atomic::compare_exchange_weak Method	Performs a `weak_atomic_compare_and_exchange` operation on `this` and returns the result.
atomic::fetch_add Method	Adds a specified value to the stored value.
atomic::fetch_and Method	Performs a bitwise `and` on a specified value and the stored value.
atomic::fetch_or Method	Performs a bitwise `or` on a specified value and the stored value.
atomic::fetch_sub Method	Subtracts a specified value from the stored value.
atomic::fetch_xor Method	Performs a bitwise `exclusive or` on a specified value and the stored value.
atomic::is_lock_free Method	Specifies whether atomic operations on `this` are lock free. An atomic type is lock free if no atomic operations on that type use locks.
atomic::load Method	Reads and returns the stored value.
atomic::store Method	Uses a specified value to replace the stored value.

Remarks

The type Ty must be trivially copyable. That is, using memcpy to copy its bytes must produce a valid Ty object that compares equal to the original object. The compare_exchange_weak and compare_exchange_strong member functions use memcmp to determine whether two Ty values are equal. These functions will not use a Ty-defined operator==. The member functions of atomic use memcpy to copy values of type Ty.

A partial specialization, atomic<Ty *>, exists for all pointer types. The specialization enables the addition of an offset to the managed pointer value or the subtraction of an offset from it. The arithmetic operations take an argument of type ptrdiff_t and adjust that argument according to the size of Ty to be consistent with ordinary address arithmetic.

A specialization exists for every integral type except bool. Each specialization provides a rich set of methods for atomic arithmetic and logical operations.

`atomic<char>`	`atomic<signed char>`	`atomic<unsigned char>`
`atomic<char16_t>`	`atomic<char32_t>`	`atomic<wchar_t>`
`atomic<short>`	`atomic<unsigned short>`	`atomic<int>`
`atomic<unsigned int>`	`atomic<long>`	`atomic<unsigned long>`
`atomic<long long>`	`atomic<unsigned long long>`

Integral specializations are derived from corresponding atomic_``integral types. For example, atomic<unsigned int> is derived from atomic_uint.

Requirements

Header: atomic

Namespace: std

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