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The simplest and probably most widely used method to swap two variables is to use a third temporary variable: define swap (x, y) temp := x x := y y := temp While this is conceptually simple and in many cases the only convenient way to swap two variables, it uses extra memory.
Many C compilers support using compare-and-swap either with the C11 <stdatomic.h> functions, [8] or some non-standard C extension of that particular C compiler, [9] or by calling a function written directly in assembly language using the compare-and-swap instruction. The following C function shows the basic behavior of a compare-and-swap ...
In the C++ Standard Library, several algorithms use unqualified calls to swap from within the std namespace. As a result, the generic std::swap function is used if nothing else is found, but if these algorithms are used with a third-party class, Foo, found in another namespace that also contains swap(Foo&, Foo&), that overload of swap will be used.
Using the XOR swap algorithm to exchange nibbles between variables without the use of temporary storage. In computer programming, the exclusive or swap (sometimes shortened to XOR swap) is an algorithm that uses the exclusive or bitwise operation to swap the values of two variables without using the temporary variable which is normally required.
Because in this program, swap operates on pointers and cannot change the pointers themselves, but only the values the pointers point to, this view holds that C's main evaluation strategy is more similar to call-by-sharing. C++ confuses the issue further by allowing swap to be declared and used with a very lightweight "reference" syntax: [50]
In a 2001 paper, Harris gives a solution to concurrent maintenance of ordered linked list that is non-blocking, using a compare-and-swap (cas) primitive. [1] Insertion of n after p is simple: next ← p.next
Copy-on-write (COW), also called implicit sharing [1] or shadowing, [2] is a resource-management technique [3] used in programming to manage shared data efficiently. Instead of copying data right away when multiple programs use it, the same data is shared between programs until one tries to modify it.
Any lock-free data structure that uses the compare-and-swap primitive must deal with the ABA problem. For example, in a lock-free stack represented as an intrusively linked list, one thread may be attempting to pop an item from the front of the stack (A → B → C).