Hi Claudio, answers inline:

On 1/6/12 8:25 AM, Claudio Martella wrote:

I hope somebody can shed some light on a piece of code i'm looking at
while working on GIRAPH-45 (and this code is also the object of
GIRAPH-95, so we'd probably get two birds with one stone here).

The code is taking care of vertex resolving in
[line 1091]:
            if (vertex != null) {
                 ((MutableVertex<I, V, E, M>) vertex).setVertexId(vertexIndex);
                 partition.putVertex((BasicVertex<I, V, E, M>) vertex);
             } else if (originalVertex != null) {

First, vertex cannot be null as it's resolved by vertexRevolver, but i
guess it's a sanity check. But the real question is: why would you
setVertex() considering it's been already initialized correctly in
Actually it can be null. Since user's can implement their own vertex resolver, they are allowed to return null from the javadoc.

     * A vertex may have been removed, created zero or more times and had
* zero or more messages sent to it. This method will handle all situations * excluding the normal case (a vertex already exists and has zero or more
     * messages sent it to).
     * @param vertexId Vertex id (can be used for {@link BasicVertex}'s
     *        initialize())
     * @param vertex Original vertex or null if none
* @param vertexChanges Changes that happened to this vertex or null if none * @param messages messages received in the last superstep or null if none * @return Vertex to be returned, if null, and a vertex currently exists
     *         it will be removed

Am I missing something or did I just realize that GIRAPH-95 is solved
by just removing that line? :)


Well, not sure about that. The set is done there I think to ensure safety. Here's the issue: Suppose that the resolve() doesn't set the vertex id correctly (i.e. in this partition). That would be a bug and probably cause issues. Probably this should be changed to be a check though. Something like...

        if (vertex != null) {
            if (vertex.getVertexId().equals(vertexIndex)) {
throw new IllegalStateException("BasicRPCCommunications: Illegal to set the vertex index differently from " + vertexIndex);
            if (originalVertex == null) {
                partition.putVertex((BasicVertex<I, V, E, M>) vertex);
            } else {

What do you think?


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