[Boost-users] [thread] UpgradeLockable Concept & Writer Starvation

Hello *, I was reading through the docs of boost::thread lib and I can't find any guarantees that when using upgrade_lock the writer (upgrader) starvation is prevented. Are there any ordering guarantees, that if some thread is going to upgrade the lock the threads which acquire the shared lock after the upgrade request will not be able to acquire the lock until the upgrade request was accomplished and released the lock? Many thanks for help, Ovanes