JBAS-4719 (JBCLUSTER-186) Invoker implementations need equal

[smarlow]

Hi,

I created JBAS-4719 yesterday for a problem that I hit in two different ways. PooledInvokerProxy doesn't have an equals method which means that comparing two instances with the same underlying address will not match.

This happens in the load balancers. A cluster membership change introduces a new arraylist of targets. After that occurs, attempts to find the current server in the new arraylist of targets will fail, even though the current server address may exist in the new arraylist of targets.

The other case is during fail-over we attempt to remove a bad server from the list of servers, but fail to remove the server for the same reason.

I attached a patch for PooledInvokerProxy to address JBAS-4719 issue.

The list of different invokers (in 4.2 branch) are:

HttpInvokerProxy
HttpInvokerProxyHA
JRMPInvoker
JRMPInvokerHA
JRMPInvokerProxy
JRMPInvokerProxyHA
LocalInvoker
UnifiedInvokerProxy
UnifiedInvokerHAProxy

Should we try to add equals/hashCode to all of the invokers?

It looks like UnifiedInvokerProxy could implement equals using its "locator" member variable. I'm not sure about the other ones.

Comments?

Scott

[brian.stansberry]

The object stored in the target list isn't the InvokerProxyHA impl. It's a:

1) RMI stub for the JRMP invoker
2) String/URL for HTTP invoker
3) ServerAddress for the PooledInvoker
4) InvokerLocator for the UnifiedInvoker EJB3

All of those implement equals/hashCode.

There was a bug in some earlier AS versions (4.0.3x, maybe 4.0.4??) where the equals/hashCode impl in ServerAddress was broken.

[smarlow]

I am seeing the issue with 4.0.4, but not for the reason that you mentioned. ServerAddress in 4.0.4 has an equals method but its not called by the PooledInvokerProxy. The PooledInvokerProxy is actually stored in the targets list (this is true for load balancing.

This would be true for anyone that switches from using RMI to org.jboss.invocation.pooled.server.PooledInvokerHA.

PooledInvokerProxy contains a ServerAddress, which should be used for the equality check.

[brian.stansberry]

OK, I see the problem. I didn't think you'd be totally off-base in a bug report; so I was scratching my head a bit. :)

Looks like this is limited to the PooledInvoker then; for the other InvokerHA impls, getStub() returns the types as I described. The value returned from that method is what populates the target list.

[smarlow]

Cool, then I don't need to worry about the other Invokers! Thanks for the feedback!

Scott

[smarlow]

4.2 + head has the fix to PooledInvokerProxy (added equals method).

Scott