So, I've been looking over these atomic structure algorithms (the ones I didn't implement already) again, now that I've got some relatively free time. I'm really having a hard time deciding whether to implement the wait-free variable.
The wait-free variable does exactly what the atomic variable does, only better: allow load/store with reserve, exchange, unconditional set, etc. The problem is that, like all the other atomic structures, the atomic variable is implemented with compare/exchange loops. This means that if there are a large number of threads setting that variable within a short period of time, a thread may have to spin for a while before it gets its turn to read the variable (one spin per thread that writes to the variable).
The wait-free variable partially circumvents this, allowing reads to be performed in constant time, regardless of how many other threads are trying to write to the variable. Writes, however, must still use compare/exchange loops (no way around that).
So, is it worth doing, or not?