[jboss-user] [JBoss AOP Development] New message: "Re: ClassPool Refactoring"

[Flavia Rainone]

User development,

A new message was posted in the thread "ClassPool Refactoring":

http://community.jboss.org/message/527265#527265

Author  : Flavia Rainone
Profile : http://community.jboss.org/people/flavia.rainone@jboss.com

Message:
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> mailto:flavia.rainone at jboss.com wrote:
>  
> My fix has never been comitted and consists of adding a check on the classes cache to BaseClassPool.get:
>  
> *public* *class* BaseClassPool *extends* AbstractClassPool
> {
>  ...
>  @Override
>    *public* *final* CtClass get(String classname) *throws* NotFoundException 
>    {
>       *boolean* trace = logger.isTraceEnabled();
>       *if* (trace) logger.trace(*this* + " initiating get of " + classname);
>  
>       *if* (this.getClassLoader() == *null*)
>       {
>          *throw* *new* IllegalStateException("Illegal call. " + " A class cannot be retrieved from ClassPool " +
>                                          *this* + " because the corresponding ClassLoader is garbage collected");
>       }
>       *try*
>       {
> >>>         *if* (this.classes.containsKey(classname))
> >>>         {
> >>>            *return* (CtClass) classes.get(classname); 
> >>>         }
>          CtClass clazz = super.get(classname);
>          *if* (trace)
>             logger.trace(*this* + " completed get of " + classname + " " + getClassPoolLogStringForClass(clazz));
>  
>          *return* clazz;
>       }
>       *catch* (NotFoundException e)
>       {
>          *if* (trace)
>             logger.trace(classname + " could not be found from " + this, e);
>          *throw* e;
>       }
>    }
> }
> 
> 
>  
> [....]
> 
>  
> 
> While working with Kabir to fix the AOP tests for AS, he pointed out that there could be an issue related to my fix. It seemed obviously right to me to look in the classes cache (a cache declared in ScopedClassPool that contains all classes created by the current class pool) before doing anything else. To me, if we have a hit in the cache, it means that the current pool is the one that is supposed to load the class, and that there is no need to look further by calling super.get method. But Kabir raised the following possibility. What if the class pool scenario (a reflection of the class loader/domain scenario) changes after the current class pool loaded the class, in a way that this class pool is no longer the one responsible for loading that class? In that case, looking for the class in the classes cache would be a serious mistake. Is this scenario possible?
Does anybody know the answer to this question? I can't commit it without knowing the answer.

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