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https://issues.apache.org/jira/browse/HADOOP-13010?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15246922#comment-15246922
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Colin Patrick McCabe commented on HADOOP-13010:
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{{ErasureCoderConf#setCoderOption}} / {{ErasureCoderConf#getCoderOption}}: I
don't see why we need to have these. If these options are generic to all
erasure encoders, then they can just go as "regular java fields" like
{{ErasureCoderConf#numDataUnits}}, etc. On the other hand, if these options
only apply to one type of Coder, then they should be stored in the particular
type of coder they apply to.
The usual way to do this is to have your Encoder / Decoder class take a
Configuration object as an argument, and pull out whatever values it needs.
For example, you might have code like this:
{code}
FoobarEncoder(Configuration conf) {
this.coderConf = new ErasureCoderConf(conf);
this.foobarity = conf.getLong("foobarity", 123);
}
{code}
The idea is that things that are specific to a class go in that class, rather
than trying to handle it with casts to and from Object.
Also, mutable configuration is unpleasant (what happens if you call
{{ErasureCoderConf#setCoderOption}} when the Encoder / Decoder has already been
created? It seems like what we actually want to do in this case is not modify
the configuration, but build a new Encoder / Decoder with a new configuration.
> Refactor raw erasure coders
> ---------------------------
>
> Key: HADOOP-13010
> URL: https://issues.apache.org/jira/browse/HADOOP-13010
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: Kai Zheng
> Fix For: 3.0.0
>
> Attachments: HADOOP-13010-v1.patch, HADOOP-13010-v2.patch,
> HADOOP-13010-v3.patch
>
>
> This will refactor raw erasure coders according to some comments received so
> far.
> * As discussed in HADOOP-11540 and suggested by [~cmccabe], better not to
> rely class inheritance to reuse the codes, instead they can be moved to some
> utility.
> * Suggested by [~jingzhao] somewhere quite some time ago, better to have a
> state holder to keep some checking results for later reuse during an
> encode/decode call.
> This would not get rid of some inheritance levels as doing so isn't clear yet
> for the moment and also incurs big impact. I do wish the end result by this
> refactoring will make all the levels more clear and easier to follow.
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