e240351d81
Semaphores allow for semi-persistent signals, compared to a condition variable which requires a mutex for proper detection. A semaphore can be 'post'ed after writing some data on one thread, and another thread will be able to recognize it quickly even if the post occured in between checking for data and waiting. This more correctly fixes a race condition with events since the mixer shouldn't be using mutexes, and arbitrary wake-ups just to make sure an event wasn't missed was quite inefficient.