[rules-dev] Lazily Enabled Truth Maintenace (Project Propsoal)

[Leonardo Gomes]

>
> if you look at the AbstractWorkingMemory insert method you'll see one
> argument is whether it's a logical insertion or not. You'll also see it
> check the global maintainTMS configuration and also retrieve the
> ObjectTypeConf. So between those things someone should be able to get it
> working.
>

Today, it enters a block where it operates on the equality map and also
creates a default handle based on that TMS global option and *regardless* of
whether it's a logical insert.

If I'm *not* putting things in the equality map for regular inserts, when a
logical insert comes in, but there were already stated inserts, how will I
know that? I would create a new handle for the logical insert and do the
tms.addLogicalDependency(...), even tough there were regular inserts before
and this seems to be a wrong behaviour.

Apparently, today, you can disable TMS and still use logical inserts in your
drl, what, I believe, will lead to inconsistent behaviour, but you're at
your own risk.

Ideas? I feel that I missed something :)

Cheers,
Leo.

P.S.: I reached the conclusions above based on the fact that
LogicalAssertionTest started failing after I did the changes you suggested.




On Wed, Sep 15, 2010 at 3:47 PM, Mark Proctor <mproctor at codehaus.org> wrote:

>  On 15/09/2010 14:35, Michael Anstis wrote:
>
> Is this in drools-core; or drools-compiler?
>
>  Whilst not undertaking to do the work; have a purpose to nose through the
> code makes understanding easier.
>
> It's all in DroolsCore.
>
> It's a 5 minute hack for me and then 15 minute unit writing test. But I
> thought I'd write it up in a hope to bring someone else into the fold, we
> need more help writting the core engine someone else out there must want to
> work on current edge engine design :)
>
> if you look at the AbstractWorkingMemory insert method you'll see one
> argument is whether it's a logical insertion or not. You'll also see it
> check the global maintainTMS configuration and also retrieve the
> ObjectTypeConf. So between those things someone should be able to get it
> working.
>
> Mark
>
>
> On 14 September 2010 16:47, Mark Proctor <mproctor at codehaus.org> wrote:
>
>>  Here is another project proposal, this time simpler. I think this one has
>> Wolfgang's name on it ;)
>>
>> http://blog.athico.com/2010/09/lazily-enabled-truth-maintenace.html
>>
>> Three weeks ago I posted the project idea for "Left and Right Unlinking"<http://blog.athico.com/2010/08/left-and-right-unlinking-community.html>.
>> So far there are no takers, so if you are interested let me know :)
>>
>> In the meantime I tried to think of a simpler enhancement that we would
>> like to see done.
>>
>> At the moment Drools has a user setting "MaintainTMSOption" which can be
>> true or false. It's a small optimisation that when turned off avoids using
>> the equality hashmap that is maintained for all inserted objects.
>>
>> It would be a much better idea to remove this configuration setting, thus
>> simplifying things for end users and have TMS lazily enabled on demand.
>>
>> For each object type there is an "ObjectTypeConf" configuration object
>> that is retrieved every time a working memory action, such as insert, is
>> executed. The enabledTMS boolean should be moved there, so there is one per
>> object type, by default it is false.
>>
>> When a working memory action occurs, like insert, it retrieved the
>> ObjectTypeConf and checks the maintainTms boolean there, instead of the
>> current engine scoped configuration. When a logical insertion occurs and the
>> ObjectTypeConf is retrieved if maintainTms is false it sets the value to
>> true and then iterates the associated ObjectTypeNode memory lazily adding
>> all the objects to the TMS equality map. From then on for that ObjectType
>> all inserted objects are added to that equality map.
>>
>> With this you now have the advantage of TMS being laziy enabled, so the
>> minor hashmap operation is no longer used and likewise a small memory saving
>> from not populating the map. There is a further advantage that this is now
>> fine grained and when enabled only impacts for that specific object type.
>>
>> A further enhancement could use a int counter, instead of a boolean. Each
>> logical insertion for that object type increases the counter, each
>> retraction decreases the counter; even if automatically retracted if the
>> truth is broken for that logical assertion. When the counter reaches zero,
>> TMS for that OTN can be disabled. We do not however remove the objects from
>> the equality map, as this would cause "churn" if TMS is continuously enabled
>> and disabled. Instead when TMS is disabled record the current fact counter
>> id. Then if TMS is disabled on a retraction but there is a counter id, we
>> can check that counter id to see if the fact is prior to TMS being disabled
>> and thus would need to be retracted from the equality map.
>>
>> _______________________________________________
>> rules-dev mailing list
>> rules-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-dev
>>
>>
>
> _______________________________________________
> rules-dev mailing listrules-dev at lists.jboss.orghttps://lists.jboss.org/mailman/listinfo/rules-dev
>
>
>
> _______________________________________________
> rules-dev mailing list
> rules-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-dev/attachments/20100918/2f82c24f/attachment.html