[jboss-jira] [JBoss JIRA] (WFLY-3661) PluggableMBeanServerImpl.findDelegateForNewObject() rejects null ObjectName arg

[Kabir Khan (JIRA)]

    [ https://issues.jboss.org/browse/WFLY-3661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12987818#comment-12987818 ] 

Kabir Khan edited comment on WFLY-3661 at 7/24/14 12:29 PM:
------------------------------------------------------------

I'm travelling with intermittent WiFi access, so I only really read the introduction. So apologies if I am about to miss something. Basically the PluggableMBeanServer has a set of delegates. One of these is the real underlying MBeanServer, the others are various read-only facades for things like the jmx representation of our management APIs, JSR77 etc. None of these facades allow registering anything.

So, I think it would be safe in this case to do something like
{code}
    @Override
    public ObjectInstance registerMBean(Object object, ObjectName name) throws InstanceAlreadyExistsException,
            MBeanRegistrationException, NotCompliantMBeanException {
        --SNIP--
            //Your explanation here :-)
            delegate = name == null ? rootMBeanServer : findDelegateForNewObject(name);
        --SNIP--
    }
{code}
I am on PTO for the next week or so, but if you feel like opening a pull request, please go ahead.


was (Author: kabirkhan):
I'm travelling with intermittent WiFi access, so I only really read the introduction. So apologies if I am about to miss something. Basically the PluggableMBeanServer has a set of delegates. One of these is the real underlying MBeanServer, the others are various read-only facades for things like the jmx representation of our management APIs, JSR77 etc. None of these facades allow registering anything.

So, I think it would be safe in this case to do something like
{code}
    @Override
    public ObjectInstance registerMBean(Object object, ObjectName name) throws InstanceAlreadyExistsException,
            MBeanRegistrationException, NotCompliantMBeanException {
        --SNIP--
            //Your explanation here :-)
            delegate = name == null ? rootMBeanServer : findDelegateForNewObject(name);
        --SNIP--
    }
{code}

> PluggableMBeanServerImpl.findDelegateForNewObject() rejects null ObjectName arg
> -------------------------------------------------------------------------------
>
>                 Key: WFLY-3661
>                 URL: https://issues.jboss.org/browse/WFLY-3661
>             Project: WildFly
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: JMX
>    Affects Versions: 8.0.0.Final
>            Reporter: Jess Holle
>            Assignee: Kabir Khan
>
> According to the Javadoc on MBeanRegistration.preRegister(), one may register an MBean with a null ObjectName and let the MBean's preRegister() method compute the ObjectName.
> Unfortunately, org.jboss.as.jmx.PluggableMBeanServerImpl.findDelegateForNewObject() violates this contract -- throwing an exception when the incoming ObjectName is null.
> This is a clear bug which breaks numerous JMX MBeans I've authored, which compute their own ObjectNames within preRegister().
> Ideally the result of preRegister would be used as an input to findDelegateForNewObject(), but unfortunately one of the inputs to preRegister() is the MBeanServer, which is, of course, what findDelegateForNewObject() is looking up.  Given this circularity, it would seem that findDelegateForNewObject() should simply return rootMBeanServer for null ObjectName inputs.  In any case it should not entirely fail to register such MBeans.
> Fortunately, I have a utility wrapper around MBean registration, so I've added the following hack immediately prior to actually registering the MBean to workaround this issue:
>       /* Hack to work around JBoss Wildfly bug (https://issues.jboss.org/browse/WFLY-3661).
>          This isn't really quite correct, of course, since this means preRegister() will get called twice,
>          but it appears to be about the best we can do.
>       */
>       if ( objectName == null )
>         if ( mbean instanceof MBeanRegistration )
>           if ( "org.jboss.as.jmx.PluggableMBeanServerImpl".equals( mbeanserver.getClass().getName() ) )
>             objectName = ((MBeanRegistration)mbean).preRegister( mbeanserver, objectName );
> where mbeanserver is obtained via ManagementFactory.getPlatformMBeanServer().



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