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

Mauricio Salatino salaboy at gmail.com
Mon Sep 20 18:17:53 EDT 2010 

nice, is it working? I would like to see the changes in the commits..
Greetings.

On Mon, Sep 20, 2010 at 7:09 PM, Mark Proctor <mproctor at codehaus.org> wrote:

>  On 20/09/2010 21:58, Leonardo Gomes wrote:
>
> Ok, it took me much longer that I had thought, but I think it's working
> now.. all tests passing except for ReteooWorkingMemoryTest that does:
>
>          FactHandle fd = workingMemory.insert( string );
>>
>>         assertEquals( 1,
>>                       tms.getAssertMap().size() );
>>
>
> Which is a good sign, since tms is now empty as long as you haven't done
> any logical insert :)
>
> I implemented just the first part of your suggestion, with a boolean. I
> will try to implement the solution with the counter later this week and
> maybe do some adjustments before submitting a patch.
>
> Do you have any suggestion in terms of unit tests that you would like to
> see or just the apparent lack of regressions is enough? Well, I can also
> think of some tests by taking ReteooWorkingMemoryTest as an example, in case
> you don't have anything particular in mind.
>
> When you do some insertions cast to get some of the internal data
> structures and check the equality map is null, maybe check the OT confs are
> false, do a logical insertion check it can turn on for specific OTNs and not
> all and that it correctly adds all objects for the OTN. This will be
> important for the next stage of the work.
>
> Mark
>
>
> Cheers,
> Leo.
>
>
>
>
> On Mon, Sep 20, 2010 at 5:14 PM, Mark Proctor <mproctor at codehaus.org>wrote:
>
>>  On 20/09/2010 15:53, Leonardo Gomes wrote:
>>
>> I think I wasn't quite clear in my last email, so let me try to
>> reformulate it:
>>
>> I also gave it a try to try to do what you suggested here (
>> http://blog.athico.com/2010/09/lazily-enabled-truth-maintenace.html),
>> Mark, and couldn't  make it work due to the following situation:
>>
>> 1) Current code seems to rely on the equality map to know that a logical
>> insert (insertLogical) for an object that has already been regularly
>> inserted (insert) should be ignored;
>>
>>  You would need to lazily maintain an equality map. When the first logical
>> insertion is done we will have to first populate that map from the Object
>> Type Node set of FactHandles.
>> In the "insert" one of the first lines is:
>>             ObjectTypeConf typeConf = this.typeConfReg.getObjectTypeConf(
>> this.entryPoint,
>>
>> object );
>>
>> So we get the ObjectTypeConf before we do anything with the object itself,
>> and we can check if TMS is being maintained for that Object Type.
>>
>>
>> 2) If I apply the modifications that you suggested, from what I
>> understood, things would start to be put in the equality map only when a
>> logical insert is issued;
>>
>> *Problem*: How would I handle the situation described in item 1, if I
>> don't have anything in the equality map at the moment a logical insert comes
>> in and I have to "lazily activate" TMS?
>>
>>  final Rete source = this.ruleBase.getRete();
>> ClassObjectType cot = new ClassObjectType( MyClass.class );
>> Map<ObjectType, ObjectTypeNode> map = source.getObjectTypeNodes(
>> EntryPoint.DEFAULT );
>> ObjectTypeNode node = map.get( cot );
>> final ObjectHashSet memory = (ObjectHashSet) workingMemory.getNodeMemory(
>> node );
>>
>> That "memory" is the set of currently asserted objects for that OTN. You
>> can now iterate that and populate the equality hash map. This is a one off
>> as the flag will be set on the ObjectTypeConf from then on and all objects
>> will be added to the equality map at the point of insertion.
>>
>> Does that help? All the information is there, you should have to know how
>> to retrieve it :) We don't currently maintain TMS for anything other than
>> the default entry point. Although I think that was a mistake and we will
>> probably move all entrypoints to work with same, but for now you can ignore
>> that and just focus on the default.
>>
>> Btw this should not be confused with "equality" mode where the equality
>> map has to be maintained by default from the start. Some would argue that a
>> rule engine should only under work and understand on the bases of equality
>> and thus all users must implement hashcode and equals correctly...
>>
>>
>> --
>>
>> Moreover, I'm willing to attempt to implement the left and right
>> un-linking and tried to start with this easier task to start to get familiar
>> with drools-core. I already read the article you linked and your article.
>> Would you have any document with an overview of the way drools implements
>> rete?
>>
>>  not really no, Rete has already well documented in a number of papers.
>> The best thing to do is get onto irc and talk directly to edson and I and we
>> can walk you through classes.
>> http://www.jboss.org/drools/irc.html
>>
>> Mark
>>
>>
>> Thanks in advance!
>>
>> Cheers,
>> Leo.
>>
>>
>>
>>
>>
>>
>> On Sat, Sep 18, 2010 at 3:49 AM, Leonardo Gomes <
>> leonardo.f.gomes at gmail.com> wrote:
>>
>>>  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
>>>>>
>>>>>
>>>>
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>>>
>>
>>
>
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