org.drools.persistence.jpa

Class JpaPersistenceContextManager

java.lang.Object

org.drools.persistence.jpa.AbstractPersistenceContextManager

org.drools.persistence.jpa.JpaPersistenceContextManager

All Implemented Interfaces:

PersistenceContextManager

public class JpaPersistenceContextManager
extends AbstractPersistenceContextManager
implements PersistenceContextManager

This class manages JpaPersistenceContext objects, and the underlying persistence context (EntityManager) instances for a persistent KieSession and other infrastructure classes that use persistence in KIE projects.

(For reference in the following documentation: the EntityManager is the class used to represent a persistence context)

There are 2 issues to take into account when looking at or modifying the code here:

1. One of the features made available here is the ability for the user to supply their own (Command Scoped) persistence context for use by the KieSession
2. However, significant race-conditions arise when a Command Scoped persistence context is used in one persistent KieSession by multiple threads. In other words, when multiple threads call operations on a Singleton persistent KieSession.

This class uses ThreadLocal instances for two things:

1. The internal Command Scoped EntityManager instance.

Field Summary

Fields inherited from class org.drools.persistence.jpa.AbstractPersistenceContextManager

appScopedEntityManager, cmdScopedEntityManager, emf, env, internalAppScopedEntityManagerFlag, internalCmdScopedEntityManagerFlag, txm

Constructor Summary

Constructors

Constructor and Description
JpaPersistenceContextManager(org.kie.api.runtime.Environment env)

Method Summary

Methods

Modifier and Type	Method and Description
void	beginCommandScopedEntityManager() This method should be called at the beginning of a CommandExecutor.execute(org.kie.api.command.Command) method, when the given CommandService instance is responsible for handling persistence.
PersistenceContext	getApplicationScopedPersistenceContext()
PersistenceContext	getCommandScopedPersistenceContext()

Methods inherited from class org.drools.persistence.jpa.AbstractPersistenceContextManager

dispose, endCommandScopedEntityManager, getApplicationScopedEntityManager, getCommandScopedEntityManager, getInternalCommandScopedEntityManager

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.drools.persistence.PersistenceContextManager

dispose, endCommandScopedEntityManager

Constructor Detail

JpaPersistenceContextManager

public JpaPersistenceContextManager(org.kie.api.runtime.Environment env)

Method Detail

getApplicationScopedPersistenceContext

public PersistenceContext getApplicationScopedPersistenceContext()

Specified by:

getApplicationScopedPersistenceContext in interface PersistenceContextManager

Returns:

a PersistenceContext instance containing the Application Scoped EntityManager.

getCommandScopedPersistenceContext

public PersistenceContext getCommandScopedPersistenceContext()

Specified by:

getCommandScopedPersistenceContext in interface PersistenceContextManager

Returns:

a PersistenceContext instance containing the Command Scoped EntityManager.

beginCommandScopedEntityManager

public void beginCommandScopedEntityManager()

Description copied from interface: PersistenceContextManager

This method should be called at the beginning of a CommandExecutor.execute(org.kie.api.command.Command) method, when the given CommandService instance is responsible for handling persistence. See the SingleSessionCommandService class.

The first responsibility of this method is to make sure that the Command Scoped EntityManager (CSEM) joins the ongoing transaction.

When the CSEM is internally managed, this method is also responsible for creating a new CSEM for use during execution of the Command or operation being executed by the KieSession.

Specified by:

beginCommandScopedEntityManager in interface PersistenceContextManager