FourStreamIndexCompressor

In the same way that a modern CPU manages a small number of prefetch streams, we keep object references short (ideally one byte) by managing a small array of Ints that point to recently accessed referenced objects. During serialization, an algorithm decides whether to reuse an existing pointer, adjusting it by a small offset, or jump to a new absolute position because there were no pointers close enough to produce an efficient relative adjustment. During deserialization, the pointers are used to reconstruct each offset or new absolute position, and the appropriate pointer is updated in exactly same way as occurred during serialization.

When an absolute pointer is used, a 0..3 counter indicates which of the four pointers should be replaced. That counter is then incremented (mod 4) to the next pointer that will be replaced.