Glossary
- activation
Moving an object from the
GHOST
state to theUPTODATE
state, load its pickled data from its jar.- data manager
The object responsible for storing and loading an object’s pickled data in a backing store. Also called a jar.
- deactivation
Moving an object from the
UPTODATE
state to theGHOST
state, discarding its pickled data.- ghost
An object whose pickled data has not yet been loaded from its jar. Accessing or mutating any of its attributes causes that data to be loaded, which is referred to as activation.
- invalidation
Moving an object from either the
UPTODATE
state or theCHANGED
state to theGHOST
state, discarding its pickled data.- jar
Alias for data manager: short for “pickle jar”, because it traditionally holds the pickled data of persistent objects.
- object cache
An MRU cache for objects associated with a given data manager.
- object id
The stable identifier that uniquely names a particular object. This is analogous to Python’s id, but unlike id, object ids remain the same for a given object across different processes.
- pickled data
The serialized data of a persistent object, stored in and retrieved from a backing store by a data manager.
- volatile attribute
Attributes of a persistent object which are not captured as part of its pickled data. These attributes thus disappear during deactivation or invalidation.