如何为drools中的子类设置不同的事件@expires

Question

Let's say I have a class representing an event (drools in stream mode) and I set expiry on that event like so:

@Role(Role.Type.EVENT)
@Expires("1m")
public class EventWithShortExpiration {}

That works fine. 1 minute after I insert this event, it is automatically retracted from working memory. Now let's say I have another class (inheriting from the above class):

@Role(Role.Type.EVENT)
@Expires("10m")
public class EventWithLongExpiration extends EventWithShortExpiration {}

So I expect the EventWithLongExpiration events to be retracted after 10m. Alternatively, I could also use a solution where the sub-class has no expiry at all, or the super class has no expiry at all, all combinations tested and didn't work.

What actually happens is that the super @expires definition always takes precedence over the subclass @expires definition. If the super class does not have an expiration at all and only the subclass has one, there's no expiration at all for either classes and objects are never retracted.

Is there any way to make this work and to have 2 different expiration policies to sub-classes?

To be clear, I want to query only the super type in my DRL queries and get instances of both super and sub-class in the same statement, but I want them to get retracted after different durations.

Answer 1

Declaration inside rule works as expected.

declare EventWithShortExpiration @role (event) @expires (1m) end
declare EventWithLongExpiration @role (event) @expires (10m) end

test

@DroolsSession("classpath:/test.drl")
public class PlaygroundTest {

    @Rule
    public DroolsAssert drools = new DroolsAssert();

    @Test
    public void testIt() {
        drools.insertAndFire(new EventWithShortExpiration(1), new EventWithLongExpiration(2));
        drools.assertFactsCount(2);

        drools.advanceTime(1, MINUTES);
        drools.assertFactsCount(1);

        drools.advanceTime(9, MINUTES);
        drools.assertFactsCount(0);
    }
}

domain

public class EventWithShortExpiration {
    public int ordinal;

    public EventWithShortExpiration(int ordinal) {
        this.ordinal = ordinal;
    }
}

public class EventWithLongExpiration extends EventWithShortExpiration {

    public EventWithLongExpiration(int ordinal) {
        super(ordinal);
    }
}

rule

declare EventWithShortExpiration @role (event) @expires (1m) end
declare EventWithLongExpiration @role (event) @expires (10m) end

rule 'test rule'
    when
        $event : EventWithShortExpiration() 
    then
        System.out.println($event.ordinal);
end

test output

00:00:00 --> inserted: EventWithShortExpiration[ordinal=1]
00:00:00 --> fireAllRules
00:00:00 <-- 'test rule' has been activated by the tuple [EventWithShortExpiration]
1
00:00:00 --> inserted: EventWithLongExpiration[ordinal=2]
00:00:00 --> fireAllRules
00:00:00 <-- 'test rule' has been activated by the tuple [EventWithLongExpiration]
2

PS: there was no luck to make annotations work as expected, most likely because of the way how annotations are read and applied. I would treat this as a drools bug. Tested on 7.28.0.Final.