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 <[email protected]
<mailto:[email protected]>> 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.
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