[eatitraw]

I understand the problem with non-atomicity, but it has nothing to do with thread-safety of calc().

Executing non-threadsafe function, and threadsafe function simultaneously is not a threadsafe operation. But the article says nothing about such situations, it places no restrictions on such situations. The thread-safe requirenment is for const-functions.

I am probably not a good explainer, so here is the link: http://stackoverflow.com/questions/14127379/does-const-mean-...