Lazy References
Lazy Loading is an essential part of EclipseStore.
The basic mechanism is best explained in the EclipseStore-Docs.
In essence java objects which are wrapped in a Lazy-Reference are not loaded with the startup of the EclipseStore-Storage but only if get() is called on them.
Lazy References are essential for big data sets that can’t get loaded into memory.
Since Spring-Data-Eclipse-Store operates with working copies using the EclipseStore-Lazy-References is not possible.
If you are using the EclipseStore-Lazy-References, all references would be resolved and loaded into memory as soon as a working copy is created, because the get()-Method is called to create a full working copy.
That’s why we implemented SpringDataEclipseStoreLazy.
The usage is the same as with the EclipseStore-Lazies, but they are handled very differently.
Simply wrap any kind of java object in the SpringDataEclipseStoreLazy-Wrapper and the wrapped object has a lazy loading behaviour.
| Lazy-References are not only loaded when needed, but also cleared when they are no longer needed! |
Example: SpringDataEclipseStoreLazy.build(new HashMap<String, Pet>())
package software.xdev.spring.data.eclipse.store.demo.complex.owner;
//...
import software.xdev.spring.data.eclipse.store.repository.lazy.SpringDataEclipseStoreLazy;
public class Owner extends Person
{
private String address;
private Lazy<List<Pet>> pets = SpringDataEclipseStoreLazy.build(new ArrayList<>());
//...Internals
SpringDataEclipseStoreLazies work as a proxy for the EclipseStore-Lazies. As far as EclipseStore is concerned, a SpringDataEclipseStoreLazy-Object is a normal Java object that contains a Lazy-Reference.
But when Spring-Data-Eclipse-Store creates the working copy, the SpringDataEclipseStoreLazy-Reference is not resolved but instead only a reference to the original Lazy-Object in EclipseStore is loaded.
As soon as get() is called on the SpringDataEclipseStoreLazy, a new working copy of the lazy object is created.