[rules-users] Events do not get removed automatically

[Wolfgang Laun]

It's right here:...

On 14/08/2012, Winfried Umbrath <wumb at gameduell.de> wrote:
> Hi guys,
>
> the drools fusion documentation states that
>
> "One of the benefits of running the engine in STREAM mode is that the
> engine can detect when an event can no longer match any rule due to its
> temporal constraints.

..."due to its temporal constraints"!

There are no such temporal constraints (to be derived from temporal
operators) in your rules; hence your "events" are just like facts, and
there is no indication to the Engine that they could or should be
retracted.

-W

> When that happens, the engine can safely retract
> the event from the session without side effects and release any
> resources used by that event."
>
> I have a hard time understanding why my events do not get removed. In
> the following example I have following rules running in stream mode:
>
> ----------------------------------------------------------------------------------------------------------------------------
> package rules
>
> import java.util.logging.Logger
>
> declare GenericEvent
>      @role(event)
>      playerIndex : long
>      eventName : String
>      card : String
>      chosenSuit : String
> end
>
> declare Table
>      currentPlayerIndex : long
>      topCard : String
> end
>
> rule "new table"
> when
>      not Table()
> then
>      insert(new Table(0,"a"));
> end
>
> rule "discardChoosing"
> when
>      $event : GenericEvent(eventName=="discardCard", $playerIndex :
> playerIndex, card.equals("c")) from entry-point "my stream"
>      $table : Table(currentPlayerIndex==$playerIndex, !topCard.equals("c"))
> then
>      Logger.getLogger("####").info("discardChoosing FIRED");
>      modify($table) {setTopCard("c")};
> end
>
> rule "choosingSuit"
>      no-loop
> when
>      $event : GenericEvent(eventName=="choosingSuit", $playerIndex :
> playerIndex, $chosenSuit : chosenSuit) from entry-point "my stream"
>      $table : Table(currentPlayerIndex==$playerIndex)
>      $discardCardEvent : GenericEvent(eventName=="discardCard",
> playerIndex==$playerIndex, card.equals("c"))  from entry-point "my stream"
> then
>      Logger.getLogger("####").info("choosingSuit FIRED");
>      modify($table)
> {setCurrentPlayerIndex($table.getCurrentPlayerIndex() + 1)};
> end
>
> rule "previousPlayer"
> when
>      $event : GenericEvent(eventName=="previousPlayer") from entry-point
> "my stream"
>      $table : Table()
> then
>      Logger.getLogger("####").info("previousPlayer FIRED");
>      modify($table)
> {setCurrentPlayerIndex($table.getCurrentPlayerIndex() - 1)};
> end
> ----------------------------------------------------------------------------------------------------------------------------
>
>
> I would expect after inserting "discardCard" followed by "choosingSuit"
> event, both should be retracted as their conditions do not evaluate to
> true anymore. But even after sleeping a couple of seconds, the rule
> "choosingSuit" fires again, which means to me the events are still in
> working memory. Here is the log output:
>
>
> inserting GenericEvent( playerIndex=0, eventName=discardCard, card=c,
> chosenSuit=null )
> INFO: discardChoosing FIRED
> INFO: choosingSuit FIRED
> inserting GenericEvent( playerIndex=0, eventName=choosingSuit,
> card=null, chosenSuit=HEARTS )
> Sleeping 9 seconds...
> Sleeping done. Printing facts:
> Fact handle: [fact 0:2:1690464956:1690464956:5:DEFAULT:Table(
> currentPlayerIndex=1, topCard=c )]
> inserting GenericEvent( playerIndex=0, eventName=previousPlayer,
> card=null, chosenSuit=null )
> INFO: previousPlayer FIRED
> INFO: choosingSuit FIRED
> INFO: previousPlayer FIRED
> INFO: choosingSuit FIRED
> INFO: previousPlayer FIRED
> INFO: choosingSuit FIRED
> INFO: previousPlayer FIRED
> INFO: choosingSuit FIRED
> INFO: previousPlayer FIRED
> ...
>
>
> I'm running Drools 5.4 and inserting/executing in this way:
> List cmds = new ArrayList();
> cmds.add(CommandFactory.newInsert(discard, "event", false, "my stream"));
> cmds.add(CommandFactory.newFireAllRules(20));
> System.out.println("inserting " + discard);
> ksession.execute(CommandFactory.newBatchExecution(cmds));
>
>
> Any help is highly appreciated.
>
>