Interlocked equivalent on Linux

Question

In a C++ Linux app, what is the simplest way to get the functionality that the Interlocked functions on Win32 provide? Specifically, a lightweight way to atomically increment or add 32 or 64 bit integers?

Answer 1

Intel's open-source ThreadBuildingBlocks has a template, Atomic, that offers the same functionality as .NET's Interlocked class.

Unlike gcc's Atomic built-ins, it's cross platform and doesn't depend on a particular compiler. As Nemanja Trifunovic correctly points out above, it does depend on the compare-and-swap CPU instruction provided by x86 and Itanium chips. I guess you wouldn't expect anything else from an Intel library : )

Answer 2

Just few notes to clarify the issue which has nothing to do with Linux.

RWM (read-modify-write) operations and those that do not execute in a single-step need the hardware-support to execute atomically; among them increments and decrements, fetch_and_add, etc.

For some architecture (including I386, AMD_64 and IA64) gcc has a built-in support for atomic memory access, therefore no external libray is required. Here you can read some information about the API.