So basically I get a stackoverflow with these two exceptions. I have to
stop/kill the server to stop them.
I think the problem is in ValueProxyCategory. It calls the function
hashCode() and this calls
AutoBeanUtils.getAllProperties(bean).hashCode();This retrieves all
properties as a Map and then calculates the hashcode for
each element. However because I have a cyclic dependency between Term and
Term2Term it will go into an infinite loop.
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor88.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at
com.google.web.bindery.autobean.vm.impl.BeanMethod$5.invoke(BeanMethod.java:155)
at
com.google.web.bindery.autobean.vm.impl.BeanMethod$1.invoke(BeanMethod.java:44)
at
com.google.web.bindery.autobean.vm.impl.SimpleBeanHandler.invoke(SimpleBeanHandler.java:43)
at
com.google.web.bindery.autobean.vm.impl.ShimHandler.hashCode(ShimHandler.java:66)
at sun.reflect.GeneratedMethodAccessor77.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at
com.google.web.bindery.autobean.vm.impl.ShimHandler.invoke(ShimHandler.java:76)
at java.util.HashMap$Entry.hashCode(HashMap.java:818)
at java.util.AbstractMap.hashCode(AbstractMap.java:494)
at
com.google.web.bindery.requestfactory.shared.impl.ValueProxyCategory.hashCode(ValueProxyCategory.java:55)
On Wed, Nov 28, 2012 at 11:24 AM, Thomas Broyer <[email protected]> wrote:
> Is there a "Caused by" for this UndeclaredThrowableException?
>
>
> On Wednesday, November 28, 2012 10:41:34 AM UTC+1, Ümit Seren wrote:
>>
>> I am not sure if this is a known issue. But I recently tried to map some JPA2
>> Entities to ValueProxy's and run into a weird issue.
>>
>> In the database I have a table (Term) which references itself using an
>> intermediate/mapping table (basically building a graph like structure).
>>
>> Term ---> Term2Term.parent
>> Term <--- Term2Term.child
>>
>> Basically a record from table A can have n childrin and exactly one
>> parent (DAG).
>>
>> The ValueProxy's look like this:
>>
>>
>> @ProxyForName(value="xxxxx")
>> public interface TermProxy extends ValueProxy {
>> public Integer getId();
>> ......
>> public Set<Term2TermProxy> getParents();
>> public Set<Term2TermProxy> getChilds();
>> }
>>
>>
>> @ProxyForName(value="xxxx")
>> public interface Term2TermProxy extends ValueProxy {
>>
>> public Integer getId();
>> public TermProxy getParent();
>>
>> public TermProxy getChild();
>>
>> }
>>
>> Furthermore I have an EntityProxy in which one Term is embedded:
>>
>>
>> @ProxyForName(xxx)
>> public interface SomeEntityProxy extends EntityProxy{
>> TermProxy getTraitOntologyTerm();
>>
>> }
>>
>> When I load the SomeEntityProxy object and also load the TermProxy I run
>> into an infinite loop on the backend/server when serializing the payload
>> with following exception:
>>
>> java.lang.reflect.**UndeclaredThrowableException
>> at $Proxy118.hashCode(Unknown Source)
>> at
>> com.google.web.bindery.**autobean.vm.impl.ShimHandler.**hashCode(ShimHandler.java:66)
>> at sun.reflect.**NativeMethodAccessorImpl.**invoke0(Native Method)
>> at
>> sun.reflect.**NativeMethodAccessorImpl.**invoke(**NativeMethodAccessorImpl.java:**57)
>> at
>> sun.reflect.**DelegatingMethodAccessorImpl.**invoke(**DelegatingMethodAccessorImpl.**java:43)
>> at java.lang.reflect.Method.**invoke(Method.java:601)
>> at
>> com.google.web.bindery.**autobean.vm.impl.ShimHandler.**invoke(ShimHandler.java:76)
>> at $Proxy118.hashCode(Unknown Source)
>> at java.util.HashMap.hash(**HashMap.java:351)
>> at java.util.HashMap.put(HashMap.**java:471)
>> at java.util.HashSet.add(HashSet.**java:217)
>> at
>> com.google.web.bindery.**requestfactory.server.**Resolver.resolveClientValue(**Resolver.java:637)
>> at
>> com.google.web.bindery.**requestfactory.server.**Resolver.access$400(Resolver.**java:51)
>> at
>> com.google.web.bindery.**requestfactory.server.**Resolver$PropertyResolver.**visitReferenceProperty(**Resolver.java:140)
>> at
>> com.google.web.bindery.**autobean.shared.**AutoBeanVisitor.**visitCollectionProperty(**AutoBeanVisitor.java:229)
>> at
>> com.google.web.bindery.**autobean.vm.impl.**ProxyAutoBean.**traverseProperties(**ProxyAutoBean.java:300)
>> at
>> com.google.web.bindery.**autobean.shared.impl.**AbstractAutoBean.traverse(**AbstractAutoBean.java:166)
>> at
>> com.google.web.bindery.**autobean.shared.impl.**AbstractAutoBean.accept(**AbstractAutoBean.java:101)
>> at
>> com.google.web.bindery.**requestfactory.server.**Resolver.resolveClientValue(**Resolver.java:414)
>>
>> I suspect that this is due to the fact that ValueProxy's don't have an
>> identity and on the backend it traverse through all properties of my
>> entity. However by having a reference from Term2Term back to Term I can
>> end up with a cyclic dependency.
>>
>> i.e. Term A -> Term2Term.parent -> Term B -> Term2Term.child -> Term A
>>
>> If I break one of the relationships (parent or child) from Term to
>> Term2Term it serializes fine. However when I adda nother ValueProxy (Term A
>> -> SomeValueProxy -> Term A ) that contains a property which maps back to
>> the Term, I again get a stackoverflow however this time on the client.
>>
>> I guess switching to EntityProxy would solve the problem as the
>> properties don't automatically get serialized and for identity the
>> stableId is used.
>>
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