[hibernate-dev] HHH-10478 : OperationContext

[Steve Ebersole]

This is going to have to wait post-5.1 as I mentioned earlier if this was
not ready prior to last week.

I have just too much on my plate to look at this over 2 days.

On Mon, Feb 8, 2016 at 12:29 AM Gail Badner <gbadner at redhat.com> wrote:

> The POC [1] assumes that we only need a single OperationContext for each
> type of operation. OperationContextManager has a Map of OperationContext by
> OperationContextType. Each OperationContext object is lazily created on the
> first occurence of the corresponding type of operation.
>
> Currently, when an operation is initiated (e.g., by Session.merge( entity
> )), OperationContextManager [2] does the following:
> - calls ManageableOperationContext#beforeOperation, which puts the
> OperationContext "in progress";
> - executes the operation, which performs cascades according to mappings;
> - calls ManageableOperationContext#afterOperation, which puts the
> OperationContext in an invalid state that is "not in progress".
>
> When an operation cascades to other entities, the same OperationContext is
> used.
>
> Obviously, OperationContextManager needs to know if an operation is
> "top-level" (meaning that the operation is on the original entity, and not
> cascaded). In the POC, if the relevant OperationContext is not in progress
> at the time that an opeation is initiated, then OperationContextManager
> assumes that the operation is top-level. If the OperationContext is "in
> progress", then OperationContextManager assumes that this is a cascaded
> operation.
>
> I am not sure this is always correct. Can anyone think of a case where this
> could break down?
>
> In the POC, the following EventSource methods that contain an argument for
> the operation cache has been deprecated and is no longer used because the
> contents of that argument has been moved into an OperationContext:
>
> public void merge(String entityName, Object object, Map copiedAlready)
> public void persist(String entityName, Object object, Map createdAlready)
> public void persistOnFlush(String entityName, Object object, Map
> copiedAlready)
> public void refresh(String entityName, Object object, Map refreshedAlready)
> public void delete(String entityName, Object child, boolean
> isCascadeDeleteEnabled, Set transientEntities)
>
> Before the POC, it was the above methods that indicated that it was not
> top-level. If it turns out that having a single OperationContext is not
> valid, then there needs to be some other way to determine if the operation
> was top-level.
>
> I had originally planned to use PersistenceContext#getCascadeLevel == 0 to
> indicate an operation was at the top-level, but I found that won't work for
> some operations. For example, the cascade level for a top-level delete can
> be > 1 when deleting orphans due to merge or save-or-update operations.
> Another example is that cascade level is not 0 on top-level save-or-update
> while flushing.
>
> I have some ideas to work around this, but I didn't want to get too far
> down that path if it wasn't an issue.
>
> Thanks,
> Gail
>
> [1]
>
> https://github.com/gbadner/hibernate-core/blob/3d0e2378cb998788b3205afb1e15c443c5ba77e8/hibernate-core/src/main/java/org/hibernate/engine/operationContext/internal/OperationContextManager.java
> [2]
>
> https://github.com/gbadner/hibernate-core/blob/3d0e2378cb998788b3205afb1e15c443c5ba77e8/hibernate-core/src/main/java/org/hibernate/engine/operationContext/internal/OperationContextManager.java#L132
>
>
> On Fri, Feb 5, 2016 at 8:17 PM, Gail Badner <gbadner at redhat.com> wrote:
>
> > I've created a gist with an overview of the design:
> > https://gist.github.com/gbadner/f0e635e8fba7b84af233 . I will add a new
> > section tomorrow about possible shortcomings.
> >
> > Here is my POC:
> >
> https://github.com/hibernate/hibernate-orm/compare/master...gbadner:HHH-10478-OperationContext
> > . Although no tests fail, the approach may be too simple to model what is
> > necessary.
> >
> > At this point the POC is squashed down to 1 commit:
> >
> https://github.com/hibernate/hibernate-orm/commit/3d0e2378cb998788b3205afb1e15c443c5ba77e8
> >
> > Have a look and feel free to comment.
> >
> > Thanks,
> > Gail
> >
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