Re: [rules-users] The effect of not using shadow facts

Chris, Right on the spot. I changed other references, but this one passed unnoticed. The correct is: Class cls = null; if ( object instanceof ShadowProxy ) { cls = ((ShadowProxy)object).getShadowedObject().getClass(); } else { cls = object.getClass(); } I made a text search this time and found no other occurence of this problem. I commited the fix in revision #13637. Take a look and let me know if you still has problems. Thank you a lot, Edson 2007/7/19, Chris West < crayzfishr(a)gmail.com&gt;: > > Edson, > > I think I've discovered the problem. In the file Rete.java, in the > method "assertObject", there is a check for shadow proxy like below: > > Class cls = object.getClass(); > if ( object instanceof ShadowProxy ) { > cls = cls.getSuperclass(); > } > > If the class being proxied was final, and your new logic chose an > interface of that class to build a proxy from, then the superclass is > Object.class. > > This leads to an incorrect selection of cachedNodes further down in the > method. > > I've traced this through the debugger with my object types, and it does > show that a node for a SortieStatus is being given an object of type > LaunchRecoveryStatusShadowProxy, which is not compatible. > > Perhaps theres a different way to determine the type of object such that > type LaunchRecoveryStatusShadowProxy will return LaunchRecoveryStatus rather > than Object. > > Please take a look and let me know if I need to provide more info. > > Thanks, > -Chris West > > On 7/18/07, Edson Tirelli < tirelli(a)post.com&gt; wrote: > > > > > > Chris, > > > > What seems to be happening us that your SortieStatus interface has > > a state attribute. Drools is trying to read this attribute value and cast it > > to LaunchRecoveryStatusShadowProxy what is causing the problems... > > Best way to solve would be to have the code so I can debug. Is it > > possible to isolate it and send me? > > > > []s > > Edson > > > > > > > > 2007/7/18, Chris West < crayzfishr(a)gmail.com&gt;: > > > > > > Edson, > > > > > > It is certainly possible to create a JDK proxy with only some of the > > > interfaces that are present on the delegate object that you are proxying, > > > but in my case, my proxies have all the interfaces of the underlying object. > > > > > > > > > The top two lines of the call stack I sent shows the following: > > > > > > Exception in thread "main" java.lang.ClassCastException: > > > ascc.status.FlightOpsStatusBoard$LaunchRecoveryStatusShadowProxy > > > at > > > org.drools.base.ascc.status.AirPlanStatusBoard$SortieStatus$getState.getValue(Unknown > > > Source) > > > > > > What's strange here is that the ClassCastException seems to be > > > caused by casting an object of type SortieStatus to type > > > LaunchRecoveryStatusShadowProxy, if I'm reading that right. The types > > > SortieStatus and LaunchRecoveryStatus are both interfaces in my code, and > > > they never appear on the same fact object (so no SortieStatus will ever be a > > > LaunchRecoveryStatus and vice-versa). So I'm wondering why the cast is > > > occuring, since it is not possible to work. > > > > > > The unfortunate part is I cannot see into the class where the cast > > > is occurring, as it is a generated class created by drools. > > > > > > -Chris West > > > > > > On 7/18/07, Edson Tirelli <tirelli(a)post.com&gt; wrote: > > > > > > > > > > > > Chris, > > > > > > > > For the solution to work, it is important that a superclass or > > > > interface matches all the ObjectTypes in your rulebase that your final class > > > > (proxy) matches... I guess that is the case with JDK proxies, isn't it? > > > > > > > > []s > > > > Edson > > > > > > > > 2007/7/18, Chris West <crayzfishr(a)gmail.com >: > > > > > > > > > > Edson, > > > > > > > > > > I downloaded and built the latest from the trunk of the > > > > > repository. I applied this new build toward my test case, and it seemed to > > > > > fix the problem. However, when I applied it to my real project, it still > > > > > exhibits the problem. If I discover more information about the problem I'll > > > > > let you know. > > > > > > > > > > Thanks, > > > > > Chris West > > > > > > > > > > On 7/17/07, Edson Tirelli < tirelli(a)post.com&gt; wrote: > > > > > > > > > > > > > > > > > > Chris, > > > > > > > > > > > > I found and developed an intermediate solution that shall > > > > > > work for your proxies. > > > > > > If it is not possible to create a shadow fact for a class > > > > > > that is asserted (because the class is final or whatever), the engine goes > > > > > > up in the class hierarchy, looking for a class or interface for which is > > > > > > possible to create the proxy, but that still matches all ObjectTypes > > > > > > available in the rule base matched by the original class. The analysis is a > > > > > > bit complex, specially because new rules with new object types can be > > > > > > dynamically added to the rule base, but I believe the solution will work for > > > > > > JDK proxies and the most common proxy frameworks out there, that usually > > > > > > don't proxy multiple unrelated interfaces at once. > > > > > > > > > > > > So, I ask you please to get latest snapshot from the > > > > > > repository and try it out for your use case and report back to the list the > > > > > > results, since seems there are a few other people using similar things. > > > > > > > > > > > > Thanks, > > > > > > Edson > > > > > > > > > > > > > > > > > > 2007/7/17, Chris West < crayzfishr(a)gmail.com&gt;: > > > > > > > > > > > > > > Is that still true if the equals() and hashcode() methods > > > > > > > are only based on the identity fields of the object (which cannot change)? > > > > > > > > > > > > > > -Chris West > > > > > > > > > > > > > > On 7/17/07, Mark Proctor <mproctor(a)codehaus.org&gt; wrote: > > > > > > > > > > > > > > > > you only need to use modifyRetract if the object is > > > > > > > > inserted. The reason for this is if you change field values on your facts we > > > > > > > > will not be able to remove them from our various internal hashmaps; thus the > > > > > > > > need to remove first prior to any changes, then make the changes and then > > > > > > > > insert it again. We can't allow users to just call update() as we have no > > > > > > > > idea what the old values where, thus we cannot find the objects in our > > > > > > > > hashmaps. > > > > > > > > > > > > > > > > Mark > > > > > > > > Chris West wrote: > > > > > > > > > > > > > > > > Mark, > > > > > > > > > > > > > > > > Using modifyRetract and modifyInsert seems to fix the > > > > > > > > problem (at least in my test case I finally created). I'll try this on my > > > > > > > > real code. > > > > > > > > > > > > > > > > My only concern here is that it puts the burden on the > > > > > > > > rule author to know whether things are being shadowed or not. For shadowing > > > > > > > > that is explicitly turned off this is ok. But for implicit non-shadowing > > > > > > > > based on a class being final, this is not at all obvious to the rule auther. > > > > > > > > > > > > > > > > > > > > > > > > Is there any way to have this hidden such that I can still > > > > > > > > call "update" but have it use "modifyRetract" and "modifyInsert" instead? > > > > > > > > > > > > > > > > Also, I'm curious why I have to call modifyRetract before > > > > > > > > I start modifing the object, since the engine does not know about my > > > > > > > > modifications anyway until I call update or modifyInsert? By the way, I was > > > > > > > > unable to use the block setter approach in the rule consequence due to not > > > > > > > > having set methods for modifying my objects. > > > > > > > > > > > > > > > > Thanks, > > > > > > > > -Chris West > > > > > > > > > > > > > > > > On 7/17/07, Mark Proctor <mproctor(a)codehaus.org > wrote: > > > > > > > > > > > > > > > > > > If you do not have shadow facts you cannot use the > > > > > > > > > update() method, it will leave the working memory corrupted. Instead you > > > > > > > > > must manage this yourself, before you change any values on the object you > > > > > > > > > must call modifyRetract() and after you hvae finished your changes ot hte > > > > > > > > > object call modifyInsert() - luckily if you are doing this in the > > > > > > > > > consequence you can use the MVEL modify keyword combined with the block > > > > > > > > > setter and it does this for you: > > > > > > > > > modify ( person ) { age += 1, location = "london" } > > > > > > > > > > > > > > > > > > Mark > > > > > > > > > Chris West wrote: > > > > > > > > > > > > > > > > > > Hello, > > > > > > > > > > > > > > > > > > With prior versions of JBoss Rules (3.0.5) I have been > > > > > > > > > using JDK generated dynamic proxies as facts, and they have been working > > > > > > > > > fine. However, after upgrading to JBoss Rules 4.0.0MR3, > > > > > > > > > I cannot seem to get the dynamic proxies to work as facts. It seems that > > > > > > > > > even though a rule fires that changes a field on the proxy, a second rule > > > > > > > > > that should not be activated after the update still fires. > > > > > > > > > > > > > > > > > > According to the JDK javadoc documentation, dynamic > > > > > > > > > proxies are created as final. My assumption is that JBoss Rules is not > > > > > > > > > creating Shadow facts for these since they are final. After reading the > > > > > > > > > JIRA at http://jira.jboss.com/jira/browse/JBRULES-960, I > > > > > > > > > now am questioning what the effect of not using shadow facts is on the > > > > > > > > > engine. The relevant part of that is: > > > > > > > > > > > > > > > > > > "The problem is that SpringAOP is generating a proxy > > > > > > > > > whose methods equals() and hashCode() are "final". As drools must either > > > > > > > > > override these methods in the shadow proxy or not shadow the fact at all, > > > > > > > > > I'm disabling shadow proxy generation for this use case. > > > > > > > > > It is really important to note that if you are asserting > > > > > > > > > SpringAOP proxies as facts into the working memory, you will not be able to > > > > > > > > > change any field value whose field is constrained in rules or you may incur > > > > > > > > > in a memory leak and non-deterministic behavior by the rules engine. > > > > > > > > > Unfortunately there is nothing we can do about, since when SpringAOP makes > > > > > > > > > the methods equals and hashcode final, we can't override them anymore and as > > > > > > > > > so, we can't shadow them." > > > > > > > > > [ Show »<http://jira.jboss.com/jira/browse/JBRULES-960>] > > > > > > > > > Edson Tirelli<http://jira.jboss.com/jira/secure/ViewProfile.jspa?name=tirell... > > > > > > > > > [02/Jul/07 03:29 PM] The problem is that SpringAOP is > > > > > > > > > generating a proxy whose methods equals() and hashCode() are "final". As > > > > > > > > > drools must either override these methods in the shadow proxy or not shadow > > > > > > > > > the fact at all, I'm disabling shadow proxy generation for this use case. It > > > > > > > > > is really important to note that if you are asserting SpringAOP proxies as > > > > > > > > > facts into the working memory, you will not be able to change any field > > > > > > > > > value whose field is constrained in rules or you may incur in a memory leak > > > > > > > > > and non-deterministic behavior by the rules engine. Unfortunately there is > > > > > > > > > nothing we can do about, since when SpringAOP makes the methods equals and > > > > > > > > > hashcode final, we can't override them anymore and as so, we can't shadow > > > > > > > > > them. > > > > > > > > > > > > > > > > > > Although I'm not using SpringAOP, I believe my facts are > > > > > > > > > not being shadowed. > > > > > > > > > > > > > > > > > > Is it true that not using shadow facts may lead to > > > > > > > > > non-deterministic behavior? Prior to shadow facts, the engine seemed to > > > > > > > > > handle it. Any chance of reverting back to the old style of truth > > > > > > > > > maintenance in the case of not using shadow facts. > > > > > > > > > > > > > > > > > > I apologize if I'm not on the right track here. My only > > > > > > > > > test case for my problem is the entire application right now, so I cannot > > > > > > > > > offer it for discussion. Any advice would be greatly appreciated. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > -Chris West > > > > > > > > > > > > > > > > > > ------------------------------ > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > > rules-users mailing list > > > > > > > > > rules-users(a)lists.jboss.org > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > > rules-users mailing list > > > > > > > > > rules-users(a)lists.jboss.org > > > > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------ > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > rules-users mailing list > > > > > > > > rules-users(a)lists.jboss.org > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > rules-users mailing list > > > > > > > > rules-users(a)lists.jboss.org > > > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > rules-users mailing list > > > > > > > rules-users(a)lists.jboss.org > > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > Edson Tirelli > > > > > > Software Engineer - JBoss Rules Core Developer > > > > > > Office: +55 11 3529-6000 > > > > > > Mobile: +55 11 9287-5646 > > > > > > JBoss, a division of Red Hat @ www.jboss.com > > > > > > > > > > > > _______________________________________________ > > > > > > rules-users mailing list > > > > > > rules-users(a)lists.jboss.org > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > rules-users mailing list > > > > > rules-users(a)lists.jboss.org > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > > > > > > > > > -- > > > > Edson Tirelli > > > > Software Engineer - JBoss Rules Core Developer > > > > Office: +55 11 3529-6000 > > > > Mobile: +55 11 9287-5646 > > > > JBoss, a division of Red Hat @ www.jboss.com > > > > > > > > _______________________________________________ > > > > rules-users mailing list > > > > rules-users(a)lists.jboss.org > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > > > _______________________________________________ > > > rules-users mailing list > > > rules-users(a)lists.jboss.org > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > -- > > Edson Tirelli > > Software Engineer - JBoss Rules Core Developer > > Office: +55 11 3529-6000 > > Mobile: +55 11 9287-5646 > > JBoss, a division of Red Hat @ www.jboss.com > > > > _______________________________________________ > > rules-users mailing list > > rules-users(a)lists.jboss.org > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > > -- Edson Tirelli Software Engineer - JBoss Rules Core Developer Office: +55 11 3529-6000 Mobile: +55 11 9287-5646 JBoss, a division of Red Hat @ www.jboss.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users