The problem as stated seems ill posed to me. If Santa wakes up when
either quorum is ready, then it's never true that both are waiting
unless they arrive simultaneously. Either that's a zero probability
event that can be safely ignored, or it needs to be handled by
arbitration in some form. Attempting to resolve contention by giving
preference to one or the other shifts the problem to that of
determining whether they're close enough to be considered
simultaneous, with edge cases needing to be resolved by arbitration,
and so on.
alt Hacker News
The problem as stated seems ill posed to me. If Santa wakes up when either quorum is ready, then it's never true that both are waiting unless they arrive simultaneously. Either that's a zero probability event that can be safely ignored, or it needs to be handled by arbitration in some form. Attempting to resolve contention by giving preference to one or the other shifts the problem to that of determining whether they're close enough to be considered simultaneous, with edge cases needing to be resolved by arbitration, and so on.