Re: NPE in AbstractCachingProcessingPipeline

[Unico Hommes]

The section fixes 
http://issues.apache.org/bugzilla/show_bug.cgi?id=31012 which is a 
serious bug in itself.

Anyway, I have found out why toCacheSourceValidities could be null when 
cachedResponse is not. Apparently this happens when the pipeline is not 
yet expired. I have committed a better fix.

--
Unico
Carsten Ziegeler wrote:
Hmm, this is imho not the best solutions. Preventing NPEs
by null checking smells a little bit :)
If the section has been added recently than that author
should now if a null for the object is a valid case or
not; otherwise we should better remove the section for 
the release.

Carsten 

 

-----Original Message-----
From: Unico Hommes [mailto:[EMAIL PROTECTED] 
Sent: Tuesday, November 16, 2004 4:00 PM
To: [EMAIL PROTECTED]
Subject: Re: NPE in AbstractCachingProcessingPipeline

The section that causes the NPE was added recently. If you 
say that there are situations where it causes an NPE then I 
believe you immediately. The code is rather incomprehensible 
to me as well to say the least. Lots of side effects and null 
states that are supposed to signal some sort of situation 
that are probably not even clear to the original author 
anymore. I guess I'll add a null check for this situation, 
when SVN is up again that is.

--
Unico
Jon Evans wrote:
   

Hi,
Bugzilla appears to be broken...
I've been chasing down a problem where the portal I'm 
     

developing would 
   

work fine for a few iterations, then it would break and bits of it 
would be replaced with "The coplet xxx is currently 
     

unavailable".  The 
   

NPE logged in error.log was pretty hard to track down, in the end I 
had to step through the code.

I tracked it down to the function 
     

getValidityForEventPipeline(), the 
   

first section of which reads:
     

       if (this.cachedResponse != null) {
           final AggregatedValidity validity = new 
AggregatedValidity();

           for (int i=0; i < this.toCacheSourceValidities.length;
i++) {
               validity.add(this.toCacheSourceValidities[i]);
           }
           return validity;
       

The problem seems to be that this.toCacheSourceValidities is null.  
This would point to the fact that setupValidities() has never been 
called - or it's internal state is such that 
     

setupValidities() ends up 
   

setting toCacheSourceValidities to null.  I don't know 
     

anything about 
   

the lifecycle of an AbstractCachingProcessingPipeline so I wouldn't 
know where to track that down.

If a !=null test is added to getValidityForEventPipeline():
     

       if (this.cachedResponse != null) {
           final AggregatedValidity validity = new 
AggregatedValidity();

           if (this.toCacheSourceValidities != null) {
               for (int i=0; i <
this.toCacheSourceValidities.length; i++) {
                   validity.add(this.toCacheSourceValidities[i]);
               }
           }
           return validity;
       

then it seems to work (at least, my portal doesn't seem to keep 
falling over any more).

If my patch isn't correct then I'd be happy to track this down 
further, if someone could point me in the right direction with some 
more information about how an 
     

AbstractCachingProcessingPipeline gets 
   

constructed, and at what point in its lifecycle setupValidities() 
should be called.

I'd appreciate some feedback / help on this one!
Thanks,
Jon