Squid internal overview

Squid storage manager (ctd - last!)
Replacement policy - LRU
Least Recently Used - objects which are used frequentlystay in the cache
Represented by placing the objects in a simple double-linked list, and placing objects at the front when they are referenced

Replacement Policy - Heap
Represented by a collection of keys (heap) where a key function determines the "position" in the heap of the object. Replacement is done on the lowest keys in the heap