[jboss-jira] [JBoss JIRA] Created: (JBCACHE-710) CacheLoader passivation/activation produces recursive exception when loader.remove fails

[Ben Wang (JIRA)]

CacheLoader passivation/activation produces recursive exception when loader.remove fails
----------------------------------------------------------------------------------------

                 Key: JBCACHE-710
                 URL: http://jira.jboss.com/jira/browse/JBCACHE-710
             Project: JBoss Cache
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: Cache loaders
    Affects Versions: 1.4.0
            Reporter: Ben Wang
         Assigned To: Manik Surtani
            Priority: Critical
             Fix For: 2.0.0


I have encountered this problem during ejb3 sfsb port of JBC1.4. This is what happened:

In ActivationInterceptor.java, we have:

            if (n != null && !n.containsKey(TreeCache.UNINITIALIZED)) {
               if (n.hasChildren()) {
                  if (allInitialized(n)) {
                     log.debug("children all initialized");
                     remove(fqn);
                  }
               } else if (loaderNoChildren(fqn)) {
                  log.debug("no children " + n);
                  remove(fqn);
               }
            }
         }
      }
      return retval;
   }

   private void remove(Fqn fqn) throws Exception {
      loader.remove(fqn);
      cache.notifyNodeActivate(fqn, false);
      if (cache.getUseInterceptorMbeans()&& statsEnabled)
         m_activations++;
   }

problem arises when loader.remove(fqn) fails (can be a file lock there, e.g.), then if I have a Cache listener to receive nodeActivate event, and in there, I will have to retrieve the node value, e.g.,

cache.get(fqn, key)

to process some logic, then get(fqn, key) will come back to ActivationInterceptor and attempt another .remove() and therefore the recursion.

A proposed fix is we should throw exception when removing the node fails in CacheLoader (I am using FileCacheLoader), e.g., DataNotRemovedException. That way, ActivationInterceptor can catch it here and skip event notification (since it won't be valid anyway).


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