>iterate through all it's parents to check if there is a cycle,which seems pretty inefficient to do for something that should never happen The number of parent

>iterate through all it's parents to check if there is a cycle,which seems pretty inefficient to do for something that should never happen The number of parents is almost always under 3 or 4 and never over 100. Writes occur a few times a second at peak. You are prematurely optimizing.