Re: Module suggestion: Atomic operations

[Bruno Haible]

Hi Marc,

> C11 has introduced atomic types and atomic operations.  When they are not
> available, one can use locks/mutexes instead.
> 
> It would be nice if there was a Gnulib module that abstracts over this,
> much like the threadlib module and friends abstract over a specific
> threading implementation.
> 
> What I am thinking of is the following: Given a type T, a new Gnulib module
> atomic allows the declaration of an atomic version of type T.  This is
> straightforward on a platform that has <stdatomic.h>.  Otherwise the atomic
> version of T would be a struct consisting of an object of type T together
> with a lock.
> 
> The rest of the module would then provide some simple atomic primitives
> like fetch_and_add, etc. that are either mapped to the C11 stdatomic
> counterparts or are implemented using the lock.

Yes, given that the platform support for these atomic types/operations is
increasing, it would accelerate the adoption if there was a Gnulib module,
like you describe it. Program developers could then adopt <stdatomic.h>
without losing portability to a number of platforms.

Personally I'm not very motivated to work on that (because in most algorithms
I've seen, mutexes/locks are the way to go, and because I find the memory_order
stuff hard to understand). But if you want to work on that, it will be
welcome!

Bruno