Sorry for the delayed response, but feel free to extend MutableVertex if
the other Vertex implementations don't meet your needs. EdgeListVertex
is probably the most commonly used simple case, but something like
IntIntNullIntVertex is very optimized for certain primitives (not
general purposed). Still, it can be nice to same more memory...
Avery
On 5/21/12 10:08 AM, Paolo Castagna wrote:
Benjamin Heitmann wrote:
On 21 May 2012, at 17:15, Paolo Castagna wrote:
A more direct question would be: are Giraph supposed to extend
BasicVertex<I,V,E,M> when they do not find a subclass of BasicVertex which
meets
their needs?
No, they are not. However this is not explicitly documented anywhere.
Or to say it more clearly: If you look in the javadoc of BasicVertex and if you
search the mailing lists,
then you will find that users are discouraged from using/extending BasicVertex,
but you will not find any suggestion of which
Vertex to extend instead. I even asked basically the same question once, and
got very indirect answers.
But that is okay, I figured it out by trial and error ;)
Users are supposed to extend HashMapVertex or EdgeListVertex (both in
org.apache.giraph.graph).
Hi Benjamin,
right, I should have seen those (this is a good sign I should stop for today
and continue tomorrow morning). I didn't because I was thinking: "I do not need
my vertexes to be mutable" (since, computing PageRank does not need to change
the topology of a graph), so I was not focusing my attention on the
MutableVertex hierarchy of classes (my mistake).
Now my question would be: why SimplePageRankVertex extends
LongDoubleFloatDoubleVertex? (But, I'll look at this tomorrow).
If you try to extend them, you will see that you can basically plug-in any kind of
existing class in the<I,V,E,M> signature,
as long as the implement the right interfaces, which are all Writable (and
WritableComparable for I).
Then you just need to add your compute() method, and you are ready to go.
Both HashMapVertex and EdgeListVertex provide implementations of all the
housekeeping that giraph needs.
Trying to work directly by extending BasicVertex will not work, as a lot of
methods are only accessibly on the same package level.
Yep.
It would probably be a good idea to submit a small javadoc patch which adds
documentation to BasicVertex, that users need to look at those other two
classes.
Yep.
Thanks again for your help and for pointing me in the right direction.
Paolo
