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From "Pinaki Poddar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (OPENJPA-1692) Add post creation callback to BrokerFactory
Date Thu, 10 Jun 2010 22:44:13 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-1692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12877608#action_12877608
] 

Pinaki Poddar commented on OPENJPA-1692:
----------------------------------------

This is an useful suggestion. The other usage of such post-initialization method hooks can
be leveraged to construct some critical internal data structures (e.g. MetaDataRepository)
that are often immutable after initialization. One can initialize these structures with thread
guards and then drop the guards for entire lifetime. This pattern will provide an opportunity
to scale/perform faster in multi-core environment.     
JPA does provide indicators such as <metadata-complete> etc to make such pattern. 

> Add post creation callback to BrokerFactory
> -------------------------------------------
>
>                 Key: OPENJPA-1692
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-1692
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: kernel
>    Affects Versions: 2.0.0, 2.1.0
>            Reporter: Rick Curtis
>            Assignee: Rick Curtis
>
> There have been a couple instances (that come to my mind) where there was the need to
do some work after creating the broker factory. Sometimes there is a necessity to ensure single
threadedness @see (PersistenceProviderImpl.postBrokerFactoryInitialization(...)), other times
we need to perform some additional configuration / initialization after the BrokerFactory
has completed (openjpa.InitializeEagerly=true). 
> I recently ran across a problem with the second case. In AbstractBrokerFactory.ctor(...)
we attempt to create a broker even though the subclassed BrokerFactory hasn't able to execute
it's constructor.
> Example pseudo code:
> abstract class AbstractBrokerFactory {
> 	AbstractBrokerFactory(Config c){
> 		// setup
> 		if(InitializeEagerly==true)
> 			this.newBroker(); <-- BAD! The subclass hasn't executed it's constructor but it
may be asked to create a new broker.
> 	}		
> }
> class ConcreteBrokerFactory extends AbstractBrokerFactory {
> 	Config _conf;
> 	ConcreteBrokerFactory (Config c){
> 		super(c);
> 		// setup
> 		_conf = c;
> 	}
> 	newBroker(){
> 		_conf.getSomething(); <-- _conf IS NULL because the constructor hasn't fully executed
yet.
> 	}
> }
> I propose that we need a postCreationCallBack method on the BrokerFactory interface.
This will be a single place that Bootstrap can drive this 'after creation ish' work.

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