Can you explain what the atomic Compare-and-Swap operation is and its application?

The Compare-and-Swap (CAS) atomic operation is a low-level operation that compares the value in memory with an expected value and, if they match, replaces it with a new value. An important property is that the operation is performed atomically, meaning it is indivisible and without interruptions.

CAS is widely used in multithreaded programming to implement lock-free algorithms and data structures, for example, in classes from the java.util.concurrent.atomic package.

Example of using CAS in Java:

AtomicInteger atomicInt = new AtomicInteger(0);
boolean updated = atomicInt.compareAndSet(0, 1); // if the current value is 0, replace it with 1

Here, compareAndSet is an implementation of CAS that guarantees the update will only occur if the value has not changed since the check.