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| [CDO] ClassCastException when setting transaction on a new branch [message #1755356] |
Thu, 02 March 2017 10:38  |
Eclipse User |
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Hello Eike,
I am updating our framework dependencies from CDO 4.4 to CDO 4.6. I now have some ClassCastExceptions on a JUnit manipulating CDO branches. I have not been able to reproduce the issue on a CDO JUnit so far. However, I have a fix but I would like to know if you see any issue with it. If the fix is acceptable to you, I will open a bugzilla and push it to gerrit.
The ClassCastException happens because the transaction.setBranch call end up creating a notification using CDONotificationBuilder.createPrimitiveNotification(int, EStructuralFeature, Class<?>, Object, Object) and the oldValue is not a Boolean or a Number as expected but CDOFeatureDelta.UNKNOWN_VALUE instead (I do not know why). This causes ClassCastException obviously.
However, If I add the 2 following instructions I do not have the exception anymore:
- In CDONotificationBuilder.createPrimitiveNotification(int, EStructuralFeature, Class<?>, Object, Object) start the method by
if(CDOFeatureDelta.UNKNOWN_VALUE.equals(oldValue)){
return new CDODeltaNotificationImpl(object, eventType, feature, oldValue, newValue);
}
- In createNotification(int, EStructuralFeature, Object, Object, int) update the third "if instruction" from "if (oldValue != null)" to
"if (oldValue != null && !CDOFeatureDelta.UNKNOWN_VALUE.equals(oldValue))"
So far I have not been able to reproduce the scenario in a CDO JUnit, because with our framework when setBranch is called, in the method CDOViewImpl.doInvalidateSynced(ViewInvalidationData), "deltas" is not empty and then it calls sendDeltaNotifications. I do not know why I have deltas in my case.
Do you have an opinion? Should I open a bugzilla even if I do not have a JUnit to reproduce the issue?
Regards,
Steve
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| Re: [CDO] ClassCastException when setting transaction on a new branch [message #1756222 is a reply to message #1755430] |
Tue, 14 March 2017 05:42  |
| Eclipse User |
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Hi Eike, Steve,
This seems to come from
http://git.eclipse.org/c/cdo/cdo.git/commit/?id=de192b0abbde6c721f376da4c747cd74f2a053c9 done for
https://bugs.eclipse.org/bugs/show_bug.cgi?id=503564
I will take one of the failing objects in our case as a sample: we have an EClass Car with an EAttribute brokenDown (default value: false).
On my current branch, I have a car CarOne with brokenDown=false.
When I call setBranch(myOtherBranch):
- I have a CDOFeatureDelta[brokendown, SET, value=false, index=0, oldValue=UNSPECIFIED]
- the old revision values are [4, [OID10], [], [], null, [], car1, null, null, [], [], []] , null correspond to brokenDown=false: default value so no value in the revision
In CDO 4.4:
- CDONotificationBuilder.getOldValue(feature) : null
- CDONotificationBuilder.createNotification: isPrimitive: oldValue==null > defaultValue
In CDO 4.6:
- ClassCasstException in CDONotificationBuilder.createNotification > CDONotificationBuilder. createPrimitiveNotification > oldValue == org.eclipse.emf.cdo.common.revision.delta.CDOFeatureDelta.UNKNOWN_VALUE, it cannot be cast in Boolean.
Looking at the code here is the difference:
In CDO 4.4:
org.eclipse.emf.internal.cdo.object.CDONotificationBuilder.visit(CDOSetFeatureDelta) {
EStructuralFeature feature = delta.getFeature();
Object oldValue = getOldValue(feature);
...
org.eclipse.emf.internal.cdo.object.CDONotificationBuilder.visit(CDOSetFeatureDelta) {
EStructuralFeature feature = delta.getFeature();
Object oldValue = delta.getOldValue();
if (oldValue == null)
{
oldValue = getOldValue(feature);
}
...
Second difference between CDO 4.4 and 4.6: UNSPECIFIED -> UNKNOWN_VALUE, but this seems to have no impact here.
I will try to create a JUnit.
Regards
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| Re: [CDO] ClassCastException when setting transaction on a new branch [message #1756249 is a reply to message #1756222] |
Tue, 14 March 2017 10:12 |
| Eclipse User |
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Eike,
I submitted a draft tests which show the ClassCastException: https://git.eclipse.org/r/#/c/93011/
Note that:
- The ClassCastException occurs with CDO native and legacy metamodels (the second test use Ecore as the branching test suite are configured to use the NATIVE model config)
- There is no Exception with MEMStore (AllTestMEMBranches) as only the resource appears to be changed.
- The ClassCastException occurs at least with AllTestDBH2Branching
- The ClassCastException does not occur with CDO 4.4.
The difference between MEMStore and DBStore is that DBStore seems to indicate that all attributes with default value have been changed (see allChangedObjects list after the call to sessionProtocol.switchTarget in CDOViewImpl.setBranchPoint)
Eike, I let you see if you want to reopen Bug 503564 or to create a new Bugzilla.
Regards
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