MineMarket State Engine

The State Engine (sometimes referred to as the Calc Engine) used in MineMarket uses light copies of the MineMarket objects. These copies of persistent objects do not have references to other persistent objects, ensuring no memory leaking.

In the past, the State Engine used full MineMarket objects loaded into memory using an initial load, with references to other objects also being loaded (for example, the reference from shipments from transactions), causing minor memory leaks that eventually resulted in out of memory errors during downstreaming.