org.datanucleus.store

Interface ObjectReferencingStoreManager

public interface ObjectReferencingStoreManager

Interface to be implemented by any StoreManager that provides objects that are actually created by the underlying datastore. This is the case with ODBMS in general where they hand out objects and those are the objects that should be managed.

Method Summary

Methods

Modifier and Type	Method and Description
void	notifyObjectIsOutdated(ObjectProvider sm) Notifies this store manager that the main memory (RAM, heap) copy of the PC object of the supplied ObjectProvider may not be regarded as valid anymore.

Method Detail

notifyObjectIsOutdated

void notifyObjectIsOutdated(ObjectProvider sm)

Notifies this store manager that the main memory (RAM, heap) copy of the PC object of the supplied ObjectProvider may not be regarded as valid anymore. (The most common case is that the state of the PC becomes HOLLOW). This is especially important for object databases employing implicit storing from the main memory to the database (like DB4O). These databases may stop tracking the main memory copy and linking it with its on-disk copy, thus releasing memory. More importantly, these databases then know that the object should be reloaded when it is (maybe even implicitly) accessed again. To be clear: There may be multiple copies of the data of one PC object (from the user perspective), namely a copy in main memory (on the Java heap) and a copy in the database (usually on disk). As there may be multiple copies, some of these copies may be outdated or invalid. In case such a copy is to be accessed, its contents should not be used. Rather than that, the outdated copy should be overwritten by an authorative copy. This method marks the main memory copy of the object (on the Java heap) to be outdated in that sense.