32 Concurrency support library [thread]

32.5 Atomic operations [atomics]

32.5.7 Class template atomic_ref [atomics.ref.generic]

32.5.7.5 Partial specialization for pointers [atomics.ref.pointer]

namespace std { template<class T> struct atomic_ref<T*> { private: T** ptr; // exposition only public: using value_type = T*; using difference_type = ptrdiff_t; static constexpr size_t required_alignment = implementation-defined; static constexpr bool is_always_lock_free = implementation-defined; bool is_lock_free() const noexcept; explicit atomic_ref(T*&); atomic_ref(const atomic_ref&) noexcept; atomic_ref& operator=(const atomic_ref&) = delete; void store(T*, memory_order = memory_order::seq_cst) const noexcept; T* operator=(T*) const noexcept; T* load(memory_order = memory_order::seq_cst) const noexcept; operator T*() const noexcept; T* exchange(T*, memory_order = memory_order::seq_cst) const noexcept; bool compare_exchange_weak(T*&, T*, memory_order, memory_order) const noexcept; bool compare_exchange_strong(T*&, T*, memory_order, memory_order) const noexcept; bool compare_exchange_weak(T*&, T*, memory_order = memory_order::seq_cst) const noexcept; bool compare_exchange_strong(T*&, T*, memory_order = memory_order::seq_cst) const noexcept; T* fetch_add(difference_type, memory_order = memory_order::seq_cst) const noexcept; T* fetch_sub(difference_type, memory_order = memory_order::seq_cst) const noexcept; T* fetch_max(T*, memory_order = memory_order::seq_cst) const noexcept; T* fetch_min(T*, memory_order = memory_order::seq_cst) const noexcept; T* operator++(int) const noexcept; T* operator--(int) const noexcept; T* operator++() const noexcept; T* operator--() const noexcept; T* operator+=(difference_type) const noexcept; T* operator-=(difference_type) const noexcept; void wait(T*, memory_order = memory_order::seq_cst) const noexcept; void notify_one() const noexcept; void notify_all() const noexcept; }; }
1
#
Descriptions are provided below only for members that differ from the primary template.
2
#
The following operations perform arithmetic computations.
The correspondence among key, operator, and computation is specified in Table 151.
🔗
T* fetch_key(difference_type operand, memory_order order = memory_order::seq_cst) const noexcept;
3
#
Mandates: T is a complete object type.
4
#
Effects: Atomically replaces the value referenced by *ptr with the result of the computation applied to the value referenced by *ptr and the given operand.
Memory is affected according to the value of order.
These operations are atomic read-modify-write operations ([intro.races]).
5
#
Returns: Atomically, the value referenced by *ptr immediately before the effects.
6
#
Remarks: The result may be an undefined address, but the operations otherwise have no undefined behavior.
7
#
For fetch_max and fetch_min, the maximum and minimum computation is performed as if by max and min algorithms ([alg.min.max]), respectively, with the object value and the first parameter as the arguments.
[Note 1: 
If the pointers point to different complete objects (or subobjects thereof), the < operator does not establish a strict weak ordering (Table 29, [expr.rel]).
— end note]
🔗
T* operator op=(difference_type operand) const noexcept;
8
#
Effects: Equivalent to: return fetch_key(operand) op operand;