value value_at(self.ring_entries) - 1 mask for indices at head and tail (don't delete masked bits! head and tail can point to the same entry, but if they are not exactly equal it implies the ring is full, and if they are exactly equal the ring is empty.)
value value_at(self.ring_entries) - 1 mask for indices at head and tail (don't delete masked bits! head and tail can point to the same entry, but if they are not exactly equal it implies the ring is full, and if they are exactly equal the ring is empty.)