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From Josh Elser <els...@apache.org>
Subject Re: [DISCUSS] Merge hbase-metrics:oahh.metrics.impl into hbase-metrics-api
Date Thu, 26 Oct 2017 21:04:33 GMT
On 10/26/17 1:55 PM, Apekshit Sharma wrote:
> bq. .....integration with metrics-library1 to support the metrics platform
> for their $business1. $business2 might want to use metrics-library2....
> Makes sense Josh.
> bq.  One final concern, bundling our "default" DropwizardMetrics 3-based
> implementation could cause headaches for users who want to build their own
> metrics-api implementation.
> Right. Do you have something in mind to avoid this?

I think the current separation of default implementation and interfaces 
as separate modules is the ideal solution.

> Thanks Josh!
> So the only remaining thing is, we should either
> - remove this (
> https://github.com/apache/hbase/blob/master/hbase-metrics-api/src/main/java/org/apache/hadoop/hbase/metrics/MetricRegistriesLoader.java#L67)
> which seems unnecessary because Service Provider will pick up
> "MetricRegistriesImpl" if it's there.

Well, the concern would be failing intuitively if the classpath is 
missing any implementation at all (unlikely, but possible).

> - Or move MetricRegistriesImpl in the same module as 'default'
> implementation. (until we have multiple implementation)
Ahh, yeah, that's not a poor idea. Took me a moment to realize there was 
both MetricRegistryImpl and MetricRegistriesImpl. I don't yet grok why 
MetricRegistries is important -- I assume the ref-counting being done 
there is important.

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