MogileFS::MogFactory - singleton class for holding some common objects.
This module holds a singleton for caching objects which are common but
relatively low in number. Such as devices, compared to fids.
This singleton is to be maintained by the parent process, and
inherited to children during fork. Post-fork, the cache is updated by
natural commands, or a monitor process pushing changes through the
parent.
The purpose is to provide a fresh cache, without forcing new
children to wait for a monitoring run before becoming useful. It also should
greatly reduce the number of simple DB queries, as those should only happen
periodically directly from the monitor job.