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From Ilkka Priha <impr...@surfeu.fi>
Subject Re: [PATCH] StackOverflowException in DescriptorRepository
Date Fri, 30 Jan 2004 15:42:22 GMT
Thanks Armin,

OJB has potential for really powerful solutions. Some additional dynamics based 
the decriptor repository, reflection and run-time byte code generation enable 
development of wonderful design patterns :-)

-- Ilkka


Armin Waibel wrote:

> Hi Ilkka,
> 
> I checked in your patch in CVS head (not in 1.0_branch).
> Many thanks!
> 
> By the way, your solution for localized resource bundles is really 
> impressive. Maybe we need a rubric "best practices".
> 
> regards,
> Armin
> 
> Ilkka Priha wrote:
> 
>> Hi,
>>
>> The attached class descriptor causes a stack overflow during a query 
>> if there are not separate class descriptors for all extent classes, 
>> too. This is because in such case they inherit the class descriptor of 
>> their parent, which causes an infinite recursion when 
>> DescriptorRepository resolves extent classes of the parent. However, 
>> this descriptor is very useful, e.g. when maintaining localized 
>> resource bundles in a database. It would be redundant to redefine the 
>> same descriptor for all supported locales.
>>
>> The following simple patch tests cyclic references and enables this 
>> kind of descriptors without side effects to current behavior.
>>
>> -- Ilkka
>>
>>
>> Index: DescriptorRepository.java
>> ===================================================================
>> retrieving revision 1.45
>> diff -u -r1.45 DescriptorRepository.java
>> --- DescriptorRepository.java    7 Jan 2004 19:11:10 -0000    1.45
>> +++ DescriptorRepository.java    29 Jan 2004 12:16:41 -0000
>> @@ -362,6 +362,12 @@
>>          {
>>              Class extentClass = (Class) iter.next();
>>              ClassDescriptor extCld = getDescriptorFor(extentClass);
>> +            if (aCld.equals(extCld))
>> +            {
>> +                // prevent infinite recursion caused by cyclic 
>> references
>> +                continue;
>> +            }
>> +
>>              if (!extCld.isInterface())
>>              {
>>                  concreteSubclasses.add(extentClass);
>> @@ -391,6 +397,12 @@
>>          {
>>              Class extentClass = (Class) iter.next();
>>              ClassDescriptor extCld = getDescriptorFor(extentClass);
>> +            if (aCld.equals(extCld))
>> +            {
>> +                // prevent infinite recursion caused by cyclic 
>> references
>> +                continue;
>> +            }
>> +
>>              if (!extCld.isInterface())
>>              {
>>                  concreteSubclassClds.add(extCld);
>>
>>
>> <class-descriptor class="org.norther.tammi.Dictionary"
>>     table="RESOURCE_LOCALE">
>>     <extent-class class-ref="tammi.manual.Dictionary_en"/>
>>     <extent-class class-ref="tammi.manual.Dictionary_fi"/>
>>     <extent-class class-ref="tammi.manual.Dictionary_sv"/>
>>     <extent-class class-ref="tammi.manual.Dictionary_fr"/>
>>     <extent-class class-ref="tammi.manual.Dictionary_de"/>
>>     <extent-class class-ref="tammi.manual.Dictionary_ru"/>
>>     <field-descriptor
>>         name="Id"
>>         column="ID"
>>         jdbc-type="BIGINT"
>>         primarykey="true"
>>         autoincrement="true"/>
>>     <field-descriptor
>>         name="Language"
>>         column="LANGUAGE"
>>         jdbc-type="VARCHAR"/>
>>     <field-descriptor
>>         name="Country"
>>         column="COUNTRY"
>>         jdbc-type="VARCHAR"/>
>>     <field-descriptor
>>         name="Variant"
>>         column="VARIANT"
>>         jdbc-type="VARCHAR"/>
>>     <collection-descriptor
>>         name="Resources"
>>         element-class-ref="fi.simsoft.tammi.LocalizedValue"
>>         refresh="true"
>>         auto-retrieve="true"
>>         auto-update="true"
>>         auto-delete="true">
>>         <inverse-foreignkey field-ref="LocaleId"/>
>>     </collection-descriptor>
>> </class-descriptor>
>>
>>
>>
>>
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>>
>>
> 
> 
> 
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> 
> .
> 



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