Can you explain what is meant by atomic operations or transactions?

An atomic operation or transaction is an operation that is executed completely or not at all, without intermediate states visible to other threads or processes. In the context of multithreading and databases, this guarantees data integrity and prevents race conditions.

For example, in Java, atomic operations can be implemented using classes from the java.util.concurrent.atomic package, such as AtomicInteger, which provide increment, decrement, and compare-and-swap operations without locks.

Example of an atomic increment:

import java.util.concurrent.atomic.AtomicInteger;

AtomicInteger counter = new AtomicInteger(0);
counter.incrementAndGet(); // atomic increment

In databases, a transaction is a set of operations that are executed as a single unit following the ACID principles (Atomicity, Consistency, Isolation, Durability). If one of the operations fails, all changes are rolled back.