Question

Is there such a thing as an atomic |= or and atomic or? If no what is the recommended technique for setting a bit in an variable that needs to be threadsafe? (I am avoiding locks)

Answer 1

There is not such thing in C++03, but you can use your vendor specific features. For example you can use InterlockedOr on windows. In C++0x you can use atomic_fetch_or.

Note that atomic operations also require locking, although it’s on the hardware level it’s still expensive.