gcj & JMX

Thu Feb 15 11:15:00 GMT 2007

Andrew Haley wrote:
> Andrew John Hughes writes:
> > On Wed, 2007年02月14日 at 18:14 +0000, Andrew Haley wrote:
> > > With Classpath, none of this ever happens. Instead,
> > > gnu.javax.management.registerMBean(Object, ObjectName) does not
> > > call MBeanRegistration.preRegister() unless ObjectName == null.
> > > 
> > > So, the preRegister method is never called.
> > > 
> > > The spec for MBeanServer.registerMBean() says "If the object
> > > name given is null, the MBean must provide its own name by
> > > implementing the MBeanRegistration interface and returning the
> > > name from the preRegister method."
> > > 
> > > I suspect, however, that if the MBean is implements the
> > > MBeanRegistration interface we should call the preRegister
> > > method regardless.
> > > 
> > > I'm going to try it.
> > 
> > Sounds good to me; I hope this fixes the problem. Maybe I
> > shouldn't stick to the specs and just go with common sense in
> > future... ;)
>> Maybe, although the spec doesn't actually say that regstration
> should only be done if there is no name, it just very strongly
> implies it. :-)

My reading of the various specs is that there's an unspoken assumption
that MBeans _may_ implement the MBeanRegistration interface _if_ they
want to do things before and after registration and/or deregistration
time, and that the spec for MBeanServer.registerMBean() merely changes
the "may" to a "must" for MBeans without a name.
Ok if I commit something like the attached patch?
Cheers,
Gary
-------------- next part --------------
Index: classpath/gnu/javax/management/Server.java
===================================================================

--- classpath/gnu/javax/management/Server.java	(revision 121990)
+++ classpath/gnu/javax/management/Server.java	(working copy)
@@ -1657,19 +1657,27 @@
 MBeanRegistration register = null;
 if (obj instanceof MBeanRegistration)
 register = (MBeanRegistration) obj;
- if (name == null)
+ if (name == null && register == null)
 {
-	if (register == null)
-	 {
-	 RuntimeException e =
-	 new IllegalArgumentException("The name was null and " +
-					 "the bean does not implement " +
-					 "MBeanRegistration.");
-	 throw new RuntimeOperationsException(e);
-	 }
+	RuntimeException e =
+	 new IllegalArgumentException("The name was null and " +
+				 "the bean does not implement " +
+				 "MBeanRegistration.");
+	throw new RuntimeOperationsException(e);
+ }
+ if (register != null)
+ {
 	try
 	 {
-	 name = register.preRegister(this, null);
+	 name = register.preRegister(this, name);
+	 if (name == null)
+	 {
+		RuntimeException e =
+		 new NullPointerException("The name returned by " +
+					 "MBeanRegistration.preRegister() " +
+					 "was null");
+		throw e;
+	 }
 	 if (sm != null)
 	 sm.checkPermission(new MBeanPermission(className, null, name,
 						 "registerMBean"));
