Re: [rules-users] Removing facts from statefulknowledgeSession's memory
Just in case anybody wonders about the effort for building a mechanism for
retracting facts based on fact attributes or other data, I outline the
solution I have implemented.
My class FactWiper implements WorkingMemoryEventListener and Runnable.
- The implementation of objectInserted( ObjectInsertedEvent event )
determines whether the object needs handling and, if so, the retraction
Date, based upon whatever strategy you care to implement, e.g., reflection
method call, Map<Class,Long>, etc. If it is to be handled, it signals
Condition "change" to the thread.
- A SortedMap<Date,Object> expiry2fact keeps track of pending
retractions.
- The thread loops into an awaitUntil( x ) on the "change" condition,
where x is (generally) the first retraction Date. If reached, it retracts
according to the foremost Map entry; if signalled it reasesses the situation
and reenters the awaitUntil.
-W
2010/11/12 Michael Anstis <michael.anstis(a)gmail.com>
A time based eviction queue is simply a queue that evicts its content
based
upon time-based heuristic. So the WorkingMemoryEventListener would store
facts inserted into the WorkingMemory in an internal queue and evict them
from that queue based upon some time-based heuristic. You could use an
Executor (ScheduledExecutorService) etc to remove facts from the queue and
working memory at set intervals.
With kind regards,
Mike
On 11 November 2010 22:31, Ayush <ayush.vatsyayan(a)alcatel-lucent.com>wrote:
>
> Can you please elaborate on "Have it store each inserted object in a
> time based eviction queue and it'll remove things for you." i.e. how can I
> do it?
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