[news.eclipse.tools.jdt] Re: 3.1M7 - JDWP - Error when methodID == zero

[Kevin Barnes <krbarnes@xxxxxxxxxx>]

Lars,
I'd suggest that you file it as a bug (JDT-Debug component).

I looked quickly at org.eclipse.jdi.internal.MethodImpl. The 
isObsolete() method is implemented as:
public boolean isObsolete() {
	if (virtualMachineImpl().isJdwpVersionGreaterOrEqual(1, 4)) {
		return fMethodID.value() == 0;
	}
	return false;
}

We may be making an incorrect assumption that any method with id of 0 is 
obsolete. This should be investigated.

Kevin



Lars Even wrote:

> Hello,
>
> I am debugging a simple application on a remote VM using Eclipse 3.1.0 
> M7. My VM is a modified version of Sun's KVM.  I have also made some 
> adjustments to the debug protocal (KDWP/JDWP).
>
> My problem is the JDWP/KDWP specified "methodID" (see definition at the 
> end of this message). Eclipse does not seem to agree that zero is a 
> valid methodID.
>
> Consider the following example
>
> 1. class Foo{
> 2. 3.     public Foo(){ 4.     // Do something
> 5.     }
> 6. 7.     public Method_1(){}
> 8.     public Method_2(){}
> 9. 10.    public static void main(){ 11.        new Foo();
> 12.    }
> 13. } 
> I have set Eclipse to communicate with the VM through a 
> KDWP-proxy-server. The KDWP-proxy-server loads the Foo-class and 
> generates the following methodsIDs:
>
> method name: Foo.<init>    methodID: 0
> method name: Method_1      methodID: 1
> method name: Method_2      methodID: 2
> method name: main          methodID: 3
>
> When I set a breakpoint at line 4, Eclipse sends an EventRequest 
> JDWP-command containing the methodID "0". After having pressed resume, I 
> get to the breakpoint, and the VM sends an Event JDWP-command. The 
> methodID is also this time "0", but this causes an internal error in 
> Eclipse.
>
> Unfortunately no details on this internal error is presented.
>
> Is this a bug?
>
>
> Thanks,         Lars E.
>
>
>
>
> *) JDWP-Specification MethodID:
>
> Uniquely identifies a method in some class in the target VM. The 
> methodID must uniquely identify the method within its class/interface or 
> any of its subclasses/subinterfaces/implementors. A methodID is not 
> necessarily unique on its own; it is always paired with a 
> referenceTypeID to uniquely identify one method. The referenceTypeID can 
> identify either the declaring type of the method or a subtype.
> (http://codenewbie.com/documentation/j2sdk-1_5_0/guide/jpda/jdwp-spec.html)