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From Andrew Purtell <apurt...@apache.org>
Subject Re: [DISCUSS] Increase stability on o.a.h.h.Tag?
Date Fri, 22 Sep 2017 17:09:10 GMT
In my opinion that's a valid use case we should support with appropriate
changes to interface annotations and, therefore, stability. I don't believe
the interfaces have been changing much, so this shouldn't represent a
problem other than maybe we want to review what we have before promoting
them. The security coprocessors do the same: they use tags to add special
metadata to cells, then apply additional logic/filtering while overriding
some scanner behavior.


On Fri, Sep 22, 2017 at 9:54 AM, Vrushali C <vrushalic2016@gmail.com> wrote:

> For what it's worth, Yarn Timeline Service v2 makes use of Tags only in the
> coprocessor code in the custom Scanner that is invoked during
> get/scan/compact and at the PrePut step.
>
> thanks
> Vrushali
>
>
> On Fri, Sep 22, 2017 at 9:20 AM, Andrew Purtell <andrew.purtell@gmail.com>
> wrote:
>
> > I think not making the relevant APIs LP(Coprocessor) was an oversight. In
> > my opinion we should do that. I'm not sure about Public. We could do that
> > too but somewhere we need to call out that coprocessors have access to
> > tags, but not clients. (Tags are removed at RPC except for replication.)
> LP
> > doesn't imply what Public might.
> >
> > > On Sep 22, 2017, at 9:11 AM, Andrew Purtell <andrew.purtell@gmail.com>
> > wrote:
> > >
> > > Tags are server side internal metadata. Some carry sensitive
> information
> > like labels. I guess this could appear odd if not around for discussion
> > when they were introduced. So what documentation can be improved to
> lessen
> > the surprise? Javadoc? Online book? A JIRA with suggestions welcome.
> > >
> > >
> > >> On Sep 22, 2017, at 9:07 AM, Josh Elser <elserj@apache.org> wrote:
> > >>
> > >> I can appreciate how we've gotten to this point, it just struck me
> > extremely odd that the contents of a Tag weren't expected to be accessed
> by
> > users. "Arbitrary metadata that rides along with a cell, you just can't
> see
> > that metadata" ;)
> > >>
> > >> I totally understand not wanting to let another thing come into 2.0.
> > Like MikeD said, let's hope for a faster 3.0 and we can slate this for
> that
> > time.
> > >>
> > >> Thanks for entertaining the discussion. We'll just deal with the
> > "downstream pain" for 2.0.
> > >>
> > >>> On 9/22/17 1:32 AM, ramkrishna vasudevan wrote:
> > >>> CellUtil  similar type of methods. Coming to Tags yes there are not
> > much
> > >>> cases where clients can directly set Tags. And I think we don't
> expose
> > any
> > >>> APIs which allow you to use mutations with Tags. So probably moving
> to
> > >>> LimitedPrivate is better and mark with Evolving if there are some
> users
> > >>> depending on the internals of Tags and its impl. But this will be a
> > One of
> > >>> case.
> > >>> And also since Tags are internal ideally the CellUtil#getTAgs()
> should
> > have
> > >>> been in another Util method that is exposed with LimitedPrivate and
> > also
> > >>> Tags if tags should be made LimitedPRivate. So this may help in not
> > having
> > >>> a PRivate interface like Tag in a public CellUtil class.
> > >>> 3.0 is fine but need some clean up in 2.0? Indicating what could
> happen
> > >>> going forward from 2.0?
> > >>> Regards
> > >>> Ram
> > >>>> On Fri, Sep 22, 2017 at 2:59 AM, Sean Busbey <busbey@apache.org>
> > wrote:
> > >>>> Yeah. I mean, I think we should improve  the situation. Just think
> > >>>> it's too much to bite off at this stage of 2.0, we can aim for
3.0
> and
> > >>>> start working in some tooling to help us.
> > >>>>
> > >>>>> On Thu, Sep 21, 2017 at 3:35 PM, Josh Elser <elserj@apache.org>
> > wrote:
> > >>>>> That really makes me groan (we have downstream users depending
on
> > code
> > >>>> we've
> > >>>>> explicitly said "don't use"), but if that's what it is given
the
> > current
> > >>>>> state, so be it. My complaining won't fix it.
> > >>>>>
> > >>>>> Thanks.
> > >>>>>
> > >>>>>
> > >>>>>> On 9/21/17 4:25 PM, Sean Busbey wrote:
> > >>>>>>
> > >>>>>> We have lots of examples of including non-Public stuff
in Public
> > APIs.
> > >>>>>> we have docs that advise folks to be wary on relying on
them
> beyond
> > >>>>>> opaque symbols.
> > >>>>>>
> > >>>>>> ref: http://hbase.apache.org/book.html#hbase.client.api.surface
> > >>>>>>
> > >>>>>>> On Thu, Sep 21, 2017 at 3:21 PM, Josh Elser <elserj@apache.org>
> > wrote:
> > >>>>>>>
> > >>>>>>> I was going to suggest LimitedPrivate in my original,
but this
> > doesn't
> > >>>>>>> make
> > >>>>>>> sense as we're exposing Public API via CellUtil.
> > >>>>>>>
> > >>>>>>> It seems odd to me that we wouldn't treat the cell
tags as a
> > supported
> > >>>>>>> API
> > >>>>>>> call. However, I'm happy to remain "confused" if the
rest of
> folks
> > >>>> don't
> > >>>>>>> consider tags to be intended for users :)
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>> On 9/21/17 3:15 PM, Ted Yu wrote:
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> Can we mark Tag LimitedPrivate ?
> > >>>>>>>>
> > >>>>>>>> We know how ATS uses Tags so it should be straight
forward to
> keep
> > >>>> their
> > >>>>>>>> usage intact.
> > >>>>>>>>
> > >>>>>>>> On Thu, Sep 21, 2017 at 12:03 PM, Josh Elser <elserj@apache.org
> >
> > >>>> wrote:
> > >>>>>>>>
> > >>>>>>>>> Hiya,
> > >>>>>>>>>
> > >>>>>>>>> (Background, I'm starting what is likely to
be an onerous task
> of
> > >>>>>>>>> looking
> > >>>>>>>>> through downstream components and seeing what
is broken with
> the
> > >>>> latest
> > >>>>>>>>> hbase-2.0.0*)
> > >>>>>>>>>
> > >>>>>>>>> Looking at YARN's use of HBase for the Application
> > TimelineServer, I
> > >>>>>>>>> see
> > >>>>>>>>> that they're relying on the Tag interface.
> > >>>>>>>>>
> > >>>>>>>>> Presently, Tag is marked as Private, yet we
expose it via the
> > Public
> > >>>>>>>>> CellUtil.
> > >>>>>>>>>
> > >>>>>>>>> My gut reaction is that we should bump Tag
up Public since the
> > intent
> > >>>>>>>>> is
> > >>>>>>>>> for downstream users to, ya know, use those
Tags. Any
> objections?
> > >>>>>>>>>
> > >>>>>>>>> If we don't want to expose Tag, we should make
a pass over the
> > Public
> > >>>>>>>>> methods and mark them as Private (so not as
to provide a Public
> > >>>> method
> > >>>>>>>>> with
> > >>>>>>>>> Private objects). CellUtil#getTag(Cell, byte)
would be one such
> > >>>>>>>>> example.
> > >>>>>>>>>
> > >>>>>>>>> - Josh
> > >>>>>>>>>
> > >>>>>>>>
> > >>>>>>>
> > >>>>>
> > >>>>
> >
>



-- 
Best regards,
Andrew

Words like orphans lost among the crosstalk, meaning torn from truth's
decrepit hands
   - A23, Crosstalk

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