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Subject: Re: Error in instantiating custom Vertex class via
 InternalVertexRunner.run
From: Benjamin Heitmann <benjamin.heitmann@deri.org>
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Date: Mon, 5 Mar 2012 17:12:26 +0000
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On 2 Mar 2012, at 23:15, Avery Ching wrote:

> If I'm reading this right, you're using a public abstract class for =
the vertex.  The vertex class must be instantiable and cannot be =
abstract.
>=20
> Hope that helps,


Thanks, that was the right issue to point out. I removed the "abstract" =
keyword, which solved the issue.=20
(Of course, then I found lots of other bugs in my code... ;)=20


After adding the abstract keyword, I ran into some problems in =
overriding "package private methods" of BasicVertex.=20
Almost all of the abstract methods in BasicVertex are declared as =
public, e.g.   public abstract Iterable<M> getMessages();

However, there are two methods which do not have the public keyword:=20
abstract void putMessages(Iterable<M> messages);
abstract void releaseResources();

I am guessing that this inconsistency is just on oversight.=20

However, if I understood everything correctly, then this provides =
problems for developers who want to implement BasicVertex=20
*outside* of the Giraph source tree. As the public keyword is missing, =
it is not possible to override these two method signatures
from another package. The result, is that if I do not need =
IntIntNullIntVertex, but instead IntMyStateNullIntVertex which =
implements BasicVertex,=20
then I will need to either copy BasicVertex to my own project, or I need =
to copy IntMyStateNullIntVertex to my local Giraph source tree.=20


Is that the right reasoning, or is there some other pattern for using =
BasicVertex which I missed ?=20

Should I file a bug report somewhere ?=20


cheers, Benjamin.=20