Portable Compare And Swap (atomic operations) C/C++ library?

c++ c multithreading portability lock-free
anon picture anon · Jul 21, 2009 · Viewed 31.9k times · Source

Is there any small library, that wrapps various processors' CAS-like operations into macros or functions, that are portable across multiple compilers?

PS. The atomic.hpp library is inside boost::interprocess::detail namespace. The author refuses to make it a public, well maintained library.

Lets reopen the question, and see if there are any other options?

Answer

Dave Goodell picture Dave Goodell · Aug 20, 2009

OPA (Open Portable Atomics) could be a good fit for your needs. https://trac.mcs.anl.gov/projects/openpa/

It provides a consistent C API to common atomic operations across multiple platforms under an MIT-style license. The library is small and certainly meets your size requirements. The current platform list is:

  • GCC inline assembly for x86, x86_64, ia64, PPC 440, and MIPS 5K processors. Several compilers with GCC-compatible-ish front-ends are also supported on the same architectures, such as icc, PGI, and IBM's xlc.
  • GCC atomic intrinsics, so most GCC-4.1+ installations are supported.
  • The SUN Solaris atomic operations library.
  • Windows NT intrinsics (although you currently have to do a little bit of extra work to build on Windows).
  • Two pseudo-platforms, pthread mutex based emulation for portability to otherwise unsupported platforms (while sacrificing some performance), and an "unsafe" implementation for use in code that is conditionally compiled to be single-threaded code.

I've never used it in a C++ program, although it ought to work with little or no changes. I'd be happy to tweak it if you run into trouble (just mail [email protected]).

Related questions

Mutex example / tutorial?

I'm new to multithreading, and was trying to understand how mutexes work. Did a lot of Googling but it still left some doubts of how it works because I created my own program in which locking didn't work. One absolutely …

Read More
Programmatically find the number of cores on a machine

Is there a way to determine how many cores a machine has from C/C++ in a platform-independent way? If no such thing exists, what about determining it per-platform (Windows/*nix/Mac)?

Read More
Windows threading: _beginthread vs _beginthreadex vs CreateThread C++

What's a better way to start a thread, _beginthread, _beginthreadx or CreateThread? I'm trying to determine what are the advantages/disadvantages of _beginthread, _beginthreadex and CreateThread. All of these functions return a thread handle to a newly created thread, I …

Read More