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https://issues.apache.org/jira/browse/GIRAPH-277?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jaeho Shin updated GIRAPH-277:
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Attachment: GIRAPH-277-2.patch
Ok, here's a new patch without the noises.
The correct reviewboard link: https://reviews.apache.org/r/6402/
(Jakob, sorry I couldn't update diff to the above, so created a new one)
In addition to minor fixes, there's a crucial one line change to the signature
of {{TextVertexWriterToEachLine#writeVertex}}.
Using wildcard type here works fine when compiled together as source at the
same time. But if I try to extend it from my own project depending on Giraph
classes as jar, then I get strange compilation error saying I'm not
implementing {{writeVertex(Vertex<I, V, E, ?>)}} even though it's already there
on the superclass even marked final. Removing the generics type variables
solves this problem so included the fix in this patch. Maybe this is another
thing we should watch out when separating message types from I/O formats.
> Text Vertex Input/Output Format base classes overhaul
> -----------------------------------------------------
>
> Key: GIRAPH-277
> URL: https://issues.apache.org/jira/browse/GIRAPH-277
> Project: Giraph
> Issue Type: Improvement
> Components: examples, lib
> Reporter: Jaeho Shin
> Attachments: GIRAPH-277-2.patch, GIRAPH-277.patch
>
>
> The current way of implementing {{VertexInputFormat}} and {{VertexReader}}
> had bad smell. It required users to understand how these two classes are
> glued together, and forced similar codes to be duplicated in every new input
> format. (Similarly for the VertexOutputFormat and VertexWriter.) Anyone who
> wants to create a new format should create an underlying record reader or
> writer at the right moment and delegate some calls to it, which seemed
> unnecessary detail being exposed. Besides, type parameters had to appear all
> over every new format code, which was extremely annoying for both reading
> existing code and writing a new one. I was very frustrated writing my first
> format code especially when I compared it to writing a new vertex code. I
> thought writing a new input/output format should be as simple as vertex.
> So, I have refactored {{TextVertexInputFormat}} and {{OutputFormat}} into new
> forms that have no difference in their interfaces, but remove a lot of burden
> for subclassing. Instead of providing static VertexReader base classes, I
> made it a non-static inner-class of its format class, which helps eliminate
> the repeated code for gluing these two, already tightly coupled classes.
> This has additional advantage of eliminating all the Generics type variables
> on the VertexReader side, which makes overall code much more concise. I
> added several useful TextVertexReader base classes that can save efforts for
> implementing line-oriented formats.
> Please comment if you see my proposed change have any impact on other
> aspects. I'm unsure of how these additional layers of abstraction could
> affect performance.
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