Slide 16 : Persistent Object Store
The Persistent Object Store (POS) is a layer on top of the LSS. In Ceda2 it supports multiple, independent PSpaces.
A PSpace is essentially a CSpace that supports persistence.
The programmer doesn’t need to be concerned with manually loading objects from disk. Instead objects are faulted into memory automatically as smart pointers (implemented using C++ templates) are dereferenced. In the literature this is called software swizzling.
Each PSpace contains a Dirty Object Set (DOS) to record all the objects that have been marked as dirty and need to be written to the LSS. The Resident Object Table (ROT) records all the persistent objects that have been faulted into memory. These are evicted on a Least Recently Used (LRU) basis.
