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https://issues.apache.org/jira/browse/OAK-2411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14282368#comment-14282368
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Marcel Reutegger commented on OAK-2411:
---------------------------------------
While {{NodeStateDiff.childNodeChanged()}} mentions that the method may be
called even though the child node did not change, the method
{{Editor.childNodeChanged()}} does not say anything about this.
Created OAK-2413 to clarify {{Editor.childNodeChanged()}}.
As an immediate fix, I will change the initializer implementations to squeeze
the base state for the MemoryNodeStore. This will avoid the issue where
MemoryNodeStates are compared with ModifiedNodeStates.
> Upgrade may fail with constraint exception
> ------------------------------------------
>
> Key: OAK-2411
> URL: https://issues.apache.org/jira/browse/OAK-2411
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: core
> Affects Versions: 1.0.9, 1.1.4
> Reporter: Marcel Reutegger
> Assignee: Marcel Reutegger
> Priority: Minor
> Fix For: 1.0.10, 1.1.5
>
>
> A repository upgrade to MongoMK sometimes fails with a constraint exception
> in PrivilegeValidator.childNodeChanged():
> {noformat}
> 18074 [main] ERROR org.apache.jackrabbit.oak.security.user.UserInitializer -
> Failed to initialize user content.
> org.apache.jackrabbit.oak.api.CommitFailedException: OakConstraint0041:
> Attempt to modify existing privilege definition jcr:nodeTypeManagement
> at
> org.apache.jackrabbit.oak.security.privilege.PrivilegeValidator.childNodeChanged(PrivilegeValidator.java:109)
> at
> org.apache.jackrabbit.oak.security.privilege.PrivilegeValidator.childNodeChanged(PrivilegeValidator.java:47)
> at
> org.apache.jackrabbit.oak.spi.commit.EditorDiff.childNodeChanged(EditorDiff.java:143)
> at
> org.apache.jackrabbit.oak.plugins.memory.MemoryNodeState.compareAgainstBaseState(MemoryNodeState.java:155)
> {noformat}
> The problem is related to the way {{NodeStateDiff.childNodeChanged()}} is
> specified:
> bq. Called for all child nodes that *may* contain changes between the before
> and after states. The comparison implementation is expected to make an effort
> to avoid calling this method on child nodes under which nothing has changed.
> When the upgrade runs, {{PriviledgeValidator.childNodeChanged()}} is called
> even though there isn't actually a difference between the before and after
> state.
> On merge() the MemoryNodeStore squeezes the current NodeState (in
> {{MemoryNodeStoreBranch.setRoot()}}). This operation turns ModifiedNodeStates
> into equivalent MemoryNodeStates. When the hooks later process the changes,
> the node state comparison happens for a state that was squeezed with one that
> wasn't. This leads to {{MemoryNodeState.compareAgainstBaseState()}} calls
> where {{after != before}} and therefore {{diff.childNodeChanged()}} is
> called, even though the actual data of the states are equal.
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