org.datanucleus.store.neodatis

Class NeoDatisPersistenceHandler

java.lang.Object

org.datanucleus.store.AbstractPersistenceHandler

org.datanucleus.store.neodatis.NeoDatisPersistenceHandler

All Implemented Interfaces:

org.datanucleus.store.StorePersistenceHandler

public class NeoDatisPersistenceHandler
extends org.datanucleus.store.AbstractPersistenceHandler

Persistence handler for persisting to NeoDatis datastores.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	neodatisDebug

Fields inherited from class org.datanucleus.store.AbstractPersistenceHandler

storeMgr

Constructor Summary

Constructors

Constructor and Description
NeoDatisPersistenceHandler(org.datanucleus.store.StoreManager storeMgr) Constructor.

Method Summary

Modifier and Type	Method and Description
void	close() Method to close the handler and release any resources.
void	deleteObject(org.datanucleus.state.ObjectProvider sm) Deletes a persistent object from the database.
void	fetchObject(org.datanucleus.state.ObjectProvider sm, int[] fieldNumbers) Fetches fields of a persistent object from the database.
Object	findObject(org.datanucleus.ExecutionContext ec, Object id) Accessor for an (at least) hollow persistable object matching the given id.
void	insertObject(org.datanucleus.state.ObjectProvider op) Inserts a persistent object into the database.
void	locateObject(org.datanucleus.state.ObjectProvider sm) Locates this object in the datastore.
void	updateObject(org.datanucleus.state.ObjectProvider op, int[] fieldNumbers) Updates a persistent object in the database.

Methods inherited from class org.datanucleus.store.AbstractPersistenceHandler

assertReadOnlyForUpdateOfObject, batchEnd, batchStart, deleteObjects, findObjects, insertObjects, locateObjects

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

neodatisDebug

public static boolean neodatisDebug

Constructor Detail

NeoDatisPersistenceHandler

public NeoDatisPersistenceHandler(org.datanucleus.store.StoreManager storeMgr)

Constructor.

Parameters:

storeMgr - Manager for the datastore

Method Detail

close

public void close()

Method to close the handler and release any resources.

insertObject

public void insertObject(org.datanucleus.state.ObjectProvider op)

Inserts a persistent object into the database. Provides persist-by-reachability using PersistFieldManager to go through all related PC fields. If this is the principal object for this thread (the object that the user invoked makePersistent on) then this will actually update the object in NeoDatis when all reachables have been processed. The reachability process means that we assign ObjectProviders down the object graph, and that object states are set up. Only a single NeoDatis "set" command is invoked per user makePersistent() call, using NeoDatis' ability to persist by reachability.

Parameters:

op - ObjectProvider of the object to be inserted.

Throws:

org.datanucleus.exceptions.NucleusDataStoreException - when an error occurs in the datastore communication

updateObject

public void updateObject(org.datanucleus.state.ObjectProvider op,
                         int[] fieldNumbers)

Updates a persistent object in the database. Provides reachability via PersistFieldManager, meaning that all PC fields that have been updated will be attached/updated too. Each call to "update" here will result in a call to NeoDatis "set".

Parameters:

op - ObjectProvider of the object to be updated.

fieldNumbers - The numbers of the fields to be updated.

Throws:

org.datanucleus.exceptions.NucleusDataStoreException - when an error occurs in the datastore communication

org.datanucleus.exceptions.NucleusOptimisticException - thrown if version checking fails

deleteObject

public void deleteObject(org.datanucleus.state.ObjectProvider sm)

Deletes a persistent object from the database. Performs delete-by-reachability ("cascade-delete") via DeleteFieldManager. If this is the primary object to be deleted (via the users deletePersistent call) then after processing the object graph will call NeoDatis "delete" for that object and use NeoDatis' delete by reachability.

Parameters:

sm - The state manager of the object to be deleted.

Throws:

org.datanucleus.exceptions.NucleusDataStoreException - when an error occurs in the datastore communication

org.datanucleus.exceptions.NucleusOptimisticException - thrown if version checking fails on an optimistic transaction for this object

fetchObject

public void fetchObject(org.datanucleus.state.ObjectProvider sm,
                        int[] fieldNumbers)

Fetches fields of a persistent object from the database. This method is called when we need to load a field. NeoDatis doesn't have a concept of "unloaded" for fields and so we may get this called when accessing an object from HOLLOW state and OM.refresh() is called, or when sm.validate() is called on it when getting it from the L1 cache.

Parameters:

sm - The state manager of the object to be fetched.

fieldNumbers - The numbers of the fields to be fetched.

Throws:

org.datanucleus.exceptions.NucleusDataStoreException - when an error occurs in the datastore communication

findObject

public Object findObject(org.datanucleus.ExecutionContext ec,
                         Object id)

Accessor for an (at least) hollow persistable object matching the given id. In this sense, the StoreManager may be seen as a kind of level-3-cache. But this methods servers an important purpose: if the StoreManager is managing the in-memory object instantiation (as part of co-managing the object lifecycle in general), then the StoreManager has to create the object during this call (if it is not already created. Most relational databases leave the in-memory object instantiation to DataNucleus, but some object databases may manage the in-memory object instantion. Implementations may simply return null, indicating that they leave the object instantiate to NeoDatis. Other implementations may instantiate the object in question (whether the implementation may trust that the object is not already instantiated has still to be determined). If an implementation believes that an object with the given ID should exist, but in fact does not exist, then the implementation should throw a RuntimeException. It should not silently return null in this case.

Parameters:

ec - execution context

id - the id of the object in question.

Returns:

a Persistable with a valid state (for example: hollow) or null, indicating that the implementation leaves the instantiation work to NeoDatis.

locateObject

public void locateObject(org.datanucleus.state.ObjectProvider sm)

Locates this object in the datastore.

Parameters:

sm - The ObjectProvider for the object to be found

Throws:

org.datanucleus.exceptions.NucleusObjectNotFoundException - if the object doesnt exist

org.datanucleus.exceptions.NucleusDataStoreException - when an error occurs in the datastore communication