[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-6998) Expand CustomEntityDirtinessStrategy to define findDirty

[Steve Ebersole (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-6998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=45249#comment-45249 ] 

Steve Ebersole commented on HHH-6998:
-------------------------------------

Here is an initial swag...

{code:title=CustomEntityDirtinessStrategy.java|borderStyle=solid}
public interface CustomEntityDirtinessStrategy {
    ...
    public void findDirty(DirtyCheckContext context, Object entity, Session session);
}
{code}

{code:title=DirtyCheckContext.java|borderStyle=solid}
public interface DirtyCheckContext {
    public static interface AttributeContext {
        public String getName();
        public Type getType();
        public Object getCurrentValue();
        public Object getLoadedValue();
    }

    public static interface AttributeChecker {
        public boolean isDirty(AttributeContext attributeContext);
    }

    public void doDirtyChecking(AttributeChecker attributeChecker);
}
{code}

Application code is already implementing {{CustomEntityDirtinessStrategy}}.  The only new requirement here is to implement {{AttributeChecker}}.  As an example consider a case where we hold a map of changed values on the entity itself:

{code:borderStyle=solid}
public class MyCustomEntityDirtinessStrategy implements CustomEntityDirtinessStrategy {
    ...
    public void findDirty(DirtyCheckContext context, final Object entity, final Session session) {
        context.doDirtyChecking(
                new AttributeChecker() {
                    public boolean isDirty(AttributeContext attributeContext) {
                        return ( (DirtyTrackingEntity) entity ).getChangedValueMap().containsKey( attributeContext.getName();
                    }
                }
        );
    }
}
{code}

> Expand CustomEntityDirtinessStrategy to define findDirty
> --------------------------------------------------------
>
>                 Key: HHH-6998
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-6998
>             Project: Hibernate ORM
>          Issue Type: Improvement
>            Reporter: Steve Ebersole
>            Assignee: Steve Ebersole
>             Fix For: 4.1.0
>
>
> {{CustomEntityDirtinessStrategy}} allows applications to bypass dirty checking in cases when they know an entity is not dirty.
> In some of these application, they also carry along the initial ("loaded") state.  In those cases it might be more performant to allow them to tell us which fields changed.  If we go this route though I'd like to take it as an opportunity to explore options for not exposing all these arrays to user code.  So partially this issue will be a discussion of possible approaches to that.

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