Garbage Collection

For garbage collection of bricks, we use a method seen in generational garbage collectors [7]. For simplicity, earlier we described each brick as having one hash table. In reality, it has a set of hash tables; each hash table has an expiration. A brick handles writes by putting state into the table with the closest expiration time after the state's expiration time. For a read, because the stub sends the key's expiration time, the brick knows which table to look in. When a table's expiration has elapsed, it is discarded, and a new one is added in its place with a new expiration.