[hibernate-dev] HHH-10478 : OperationContext

[Steve Ebersole]

I do like the proposal.  Awesome job on the gist.  I'll look over the code
over the next few days.

On Thu, Mar 31, 2016 at 3:05 PM Gail Badner <gbadner at redhat.com> wrote:

> Replying for consideration for 6.0.
>
> On Mon, Feb 8, 2016 at 6:12 AM, Steve Ebersole <steve at hibernate.org>
> wrote:
>
>> 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
>>> >
>>> _______________________________________________
>>> hibernate-dev mailing list
>>> hibernate-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>
>>
>