hi folks!
I'm right now cleaning up old code in our enhancer. Like removing java5 hacks,
etc
This is also triggered by our recent discussion about _transform and other
pieces.
Slowly getting my head into the right space for it. This is way more complex
than I remembered ;)
So here is my next puzzle:
I've created a new example with 2 classes: Person and Employee extends Person
Plus a persistence.xml with enlisting those 2 classes (makes a difference!) and
essentially
<property name="openjpa.DynamicEnhancementAgent" value="true"/>
<property name="openjpa.RuntimeUnenhancedClasses" value="supported"/>
The reason I switched on RuntimeUnenhancedClasses is that this check is
performed when the BrokerFactory gets created.
And if the classes are not build-time enhanced, then it fails in
org.apache.openjpa.enhance.ManagedClassSubclasser#prepareUnenhancedClasses
if (conf.getRuntimeUnenhancedClassesConstant() !=
RuntimeUnenhancedClassesModes.SUPPORTED) { ..
And if you switch to supported, then it will create a new subclass and replaces
field access to the getters/setters. Sadly
java.lang.instrument.Instrumentation#retransform cannot be used to add new
fields or methods. Otherwise we could do a direct full replacement of this
class.
Fun thing is that later on in
org.apache.openjpa.persistence.PersistenceProviderImpl#createEntityManagerFactory(java.lang.String,
java.lang.String, java.util.Map)
we call loadAgent(factory);
But what is it supposed to do? Which cases does it serve?
If the classes did not have been already enhanced at build time nor via
javaagent they will now be subclassed by ManagedClassSubclasser.
And if we do not set RuntimeUnenhancedClasses=supported then we will never make
it so far but blow up way earlier.
Also: it is nice to have that agent attached. But why? All the entity classe
already have been loaded already during BrokerFactory startup. There is no more
entity class left over which needs enhancement, isn't?
This is the log I get which reflects what I mean. Happy to share the code in a
playground branch.
1261 test-classtransform INFO [main] openjpa.Enhance - Creating subclass
and redefining methods for "[class
org.apache.openjpa.examples.dynenhance.Employee, class
org.apache.openjpa.examples.dynenhance.Person]". This means that your
application will be less efficient than it would if you ran the OpenJPA
enhancer.
1412 test-classtransform INFO [main] openjpa.Runtime - OpenJPA dynamically
loaded the class enhancer. Any classes that were not enhanced at build time
will be enhanced when they are loaded by the JVM.
LieGrue,
strub
