atomic_compare_exchange

Defined in header <Kokkos_Atomic.hpp> which is included from <Kokkos_Core.hpp>

Usage

auto old = atomic_compare_exchange(&obj, expected, desired);

Atomically compares the current value of obj with expected, replaces its value with desired if equal, and always returns the previously stored value at the address &obj regardless of whether the exchange has happened or not.

Description

template<class T>
T atomic_compare_exchange(T *ptr, std::type_identity_t<T> expected, std::type_identity_t<T> desired);

Atomically compares *ptr with expected, and if those are bitwise-equal, replaces the former with desired, and always returns the actual value that was pointed to by ptr before the call.

{ old = *ptr; if (old == expected) *ptr = desired; return old; }

Parameters:

  • ptr – address of the object to test and to modify

  • expected – value expected to be found in the object

  • desired – the value to store in the object if as expected

Returns:

the value held previously by the object pointed to by ptr

See also

  • atomic_exchange: atomically replaces the value of the referenced object and obtains the value held previously