Code review comment for lp:~robertcarr/mir/improve-input-acceptance

The code Kevin highlighted does look a bit odd - overly verbose (two tests for "appeared") and dealing with spurious wakeups strangely. The canonical form is:

while (!/*condition*/)
{
   if (cv.wait_until(lock, deadline) == st::cv_status::timeout)
     throw /* timed out */;
}