Structs

Implements the virtual scheduling description of the Generic Cell Rate Algorithm, attributed to ITU-T in recommendation I.371 Traffic control and congestion control in B-ISDN; from Wikipedia.
Implements the industry-standard leaky bucket rate-limiting as-a-meter. The bucket keeps a “fill height”, pretending to drip steadily (which reduces the fill height), and increases the fill height with every cell that is found conforming. If cells would make the bucket overflow, they count as non-conforming.