You're mostly on the right track.
The one thing you have to watch out for is concurrent access to the publishable data, because you don't want one thread clobbering it while another is trying to read it. To prevent that, use a pair of buffers and a mutex-protected pointer to whichever one is considered current. When process_data() has something ready, it should dump its results in the non-current buffer, lock the pointer mutex, repoint the pointer to the buffer containing the new data and then release the mutex. Similarly, the publisher should lock the pointer mutex while it reads the current data, which will force anything that might want to clobber it to wait. This is a bit more complex than having a single, mutex-protected buffer but will assure that you always have something current to publish while new data is being prepared.
If your processing step takes long enough that you could get multiple sets of data to read, you might split the read/process thread into two and let the reader make sure the processor only ever gets the latest and greatest so you don't end up processing stuff you won't ever publish.
Excellent first question, by the way. Have an upvote.
