Lockless patterns: an introduction to compare-and-swap

In the first part of this series, I showed you the theory behind concurrent memory models and how that theory can be applied to simple loads and stores. However, loads and stores alone are not a practical tool for the building of higher-level synchronization primitives such as spinlocks, mutexes, and condition variables. Even though it is possible to synchronize two threads using the full memory-barrier pattern that was introduced last week (Dekker's algorithm), modern processors provide a way that is easier, more generic, and faster—yes, all three of them—the compare-and-swap operation.

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