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From Sean Busbey <bus...@cloudera.com>
Subject Re: Clarifying interface evolution freedom in patch releases (was: Re: [VOTE] Third release candidate for HBase 1.0.1 (RC2))
Date Thu, 23 Apr 2015 21:04:06 GMT
I'm fine with us adding methods to public APIs in patch releases so long as
we stop claiming to follow semver. We can say we take the principles of
semver as inspiration. This would reflect the current state of the world
WRT 1.0.1 and would still give us a reason keep the narrower definition of
"new features" in minor versions.


No longer claiming semver would also have the added benefit of making it
for me to easier to explain our compatibility promises to people. Right now
I have to explain the difference between the things that get proper semver
treatment (e.g. public api, wire compat) and which things are downgraded to
breaking-on-minor (e.g. LimitedPrivate, binary compatibility). Starting
with the context of "we like semver" will be easier than "we use semver".


Like Josh, my main concern is that we accurately advertise what we're
doing. There are few things I've found more frustrating than being an end
user of a project that claims to follow semver without understanding the
burden that carries (and subsequently not meeting it).

On Thu, Apr 23, 2015 at 3:48 PM, Stack <stack@duboce.net> wrote:

> I agree w/ the Enis characterization (so we need the callout on semvar) but
> think we should practice what Seans says (patch is bug fixes only).
> St.Ack
>
> On Thu, Apr 23, 2015 at 1:31 PM, Sean Busbey <busbey@cloudera.com> wrote:
>
> > Why don't we just focus development after a minor release on the next
> minor
> > release instead of the next patch release?
> >
> > We could limit backports to the patch releases to critical bugs, which
> > would cut down on how often someone has to deal with the pain of making
> > sure we don't add to public APIs. It also reduces the risk someone going
> > through an upgrade has, since there are fewer changes.
> >
> > If someone fixes a bug and doesn't want to do the work of making sure it
> > doesn't add methods in a patch release, they just don't backport to that
> > version and make a follow on e.g. "backport to 1.0.z" ticket.
> >
> >
> >
> > On Thu, Apr 23, 2015 at 1:50 PM, Enis Söztutar <enis.soz@gmail.com>
> wrote:
> >
> > > +1 to the proposal.
> > >
> > > The problem is that we have a very big API surface especially with the
> > > coprocessors included in the report. Even simple bug fixes can
> introduce
> > > protected or public methods to base classes, which makes patch releases
> > > very hard to maintain. I would not want to spend the effort to spend
> tons
> > > of time trying to make a patch not introduce new methods in order to
> > > backport. That effort can be spent elsewhere IMO.
> > >
> > > Looking at the report
> > > https://people.apache.org/~enis/1.0.0_1.0.1RC2_compat_report.html,
> > nothing
> > > strikes me as "new functionality". Going from current 1.0.0 to 1.0.1RC2
> > > should actually be as you would expect from upgrading a patch release.
> > >
> > > Yes, adding new API in patch releases will make downgrading harder,
> but I
> > > think that is an acceptable tradeoff. We can document that if your
> > > application compiles (meaning that you are not using new API) with
> 1.0.0,
> > > then you can swap your jars in a binary compat manner.
> > >
> > > Enis
> > >
> > > On Thu, Apr 23, 2015 at 10:03 AM, Andrew Purtell <apurtell@apache.org>
> > > wrote:
> > >
> > > > Anyone disagree with the point of view put forward by Josh and Sean?
> > > >
> > > >
> > > > On Wed, Apr 22, 2015 at 10:35 AM, Josh Elser <josh.elser@gmail.com>
> > > wrote:
> > > >
> > > > > Andy -- I understood your intent, but thanks for clarifying. (as
> well
> > > as
> > > > > taking the time to break this discussion out in the first place).
I
> > > agree
> > > > > with your assessment.
> > > > >
> > > > > re: Sean's comments, if it wasn't clear by me asking in the first
> > > place,
> > > > I
> > > > > also think sticking as close as possible to semver's rules is the
> > best
> > > > > approach, although I'm getting the impression that there have been
> > some
> > > > > previous reservations to doing so (especially by your comment about
> > > > > backporting features if there is demand is).
> > > > >
> > > > > I've found adhering to the bug-fix release restrictions can be a
> very
> > > > > painful and time-consuming task, so this is something to get a
> > > > > representative sampling of those who do the work to make sure
> > everyone
> > > is
> > > > > on board.
> > > > >
> > > > >
> > > > > Sean Busbey wrote:
> > > > >
> > > > >> I'd much rather we stick with the definitions used in Semantic
> > > > Versioning.
> > > > >> Our use is already confusing enough given our matrix of
> > > compatibilities
> > > > >> that don't get "major version for breaking" protections.
> > > > >>
> > > > >> We've previously discussed how we'll do additional minor releases
> > when
> > > > >> there's sufficient interest in the new features present there.
> > What's
> > > > >> building that demand if any backwards compatible change can go
> back
> > > > into a
> > > > >> patch release?
> > > > >>
> > > > >> Would we have an easier time restraining ourselves if we had
a
> > regular
> > > > >> schedule planned around new minor versions?
> > > > >>
> > > > >>
> > > > >> On Wed, Apr 22, 2015 at 12:03 PM, Josh Elser<josh.elser@gmail.com
> >
> > > > >> wrote:
> > > > >>
> > > > >>  While I can understand the desire to want to add things, I do
> think
> > > it
> > > > >>> makes things harder for users to reliably write code against
> > versions
> > > > of
> > > > >>> HBase which (by their view) should be completely compatible
with
> > one
> > > > >>> another.
> > > > >>>
> > > > >>> Take this extremely hypothetical situation: I'm new to HBase
and
> > > start
> > > > >>> writing some code against HBase 1.0.1 which was just deployed
at
> my
> > > > >>> $job. I
> > > > >>> don't _know_ what APIs are new, I just know what exists and
treat
> > > that
> > > > as
> > > > >>> acceptable for me to be using. Meanwhile in production, some
> other
> > > > people
> > > > >>> find a bug with HBase 1.0.1 and roll back to 1.0.0 which
they had
> > > been
> > > > >>> previously using. My reaction would be "of course my code
should
> > work
> > > > >>> with
> > > > >>> HBase 1.0.0, I only used the public API" when in fact this
is not
> > > true.
> > > > >>>
> > > > >>> Personally, I think it's a little bold to say semver is even
in
> use
> > > if
> > > > >>> this principal isn't being followed as it doesn't follow
at all
> > with
> > > my
> > > > >>> understanding on the guarantees defined by semver for bug-fix
> > > releases.
> > > > >>>
> > > > >>> That being said, if the intent *is* to allow ourselves to
make
> > these
> > > > >>> sorts
> > > > >>> of changes, I just think some sort of disclaimer should be
> present:
> > > > >>>
> > > > >>> - HBase uses Semantic Versioning for its release versioning
> > > > >>> + HBase uses Semantic Versioning for its release versioning
with
> a
> > > > caveat
> > > > >>> that methods and members might be added in newer bug-fix
releases
> > > that
> > > > >>> were
> > > > >>> not present in the previous bug-fix release.
> > > > >>>
> > > > >>>
> > > > >>> Andrew Purtell wrote:
> > > > >>>
> > > > >>>  [Subject changed]
> > > > >>>>
> > > > >>>> On Tue, Apr 21, 2015 at 8:47 PM, Josh Elser<
> josh.elser@gmail.com>
> > > > >>>>  wrote:
> > > > >>>>
> > > > >>>>   I was a little surprised when I noticed method additions
to
> > > > >>>>
> > > > >>>>> InterfaceAudience.Public annotated classes. This
means that a
> > user
> > > > >>>>> could
> > > > >>>>> write code against 1.0.1 that would not work against
1.0.0
> which
> > > > seems
> > > > >>>>> undesirable for a bugfix release. I read over the
book section
> on
> > > > >>>>> compatibility and didn't see this addressed, so I
thought I'd
> > ask.
> > > > >>>>>
> > > > >>>>>
> > > > >>>> Let's clarify this. It's not the first time this question
has
> been
> > > > >>>> asked.
> > > > >>>>
> > > > >>>> To get things moving:
> > > > >>>>
> > > > >>>> I propose the following addition to the "Client API
> compatibility"
> > > > >>>> section
> > > > >>>> of Section 11.1:
> > > > >>>>
> > > > >>>> + APIs available in a patch version will be available
in all
> later
> > > > >>>> + patch versions. However, new APIs may be added which
will not
> be
> > > > >>>> + available in earlier patch versions.
> > > > >>>>
> > > > >>>> I propose the following change to the "Client Binary
> > compatibility"
> > > > >>>> section
> > > > >>>> of Section 11.1:
> > > > >>>>
> > > > >>>> - Old client code can run unchanged (no recompilation
needed)
> > > against
> > > > >>>> new
> > > > >>>> jars.
> > > > >>>> + Client code written to APIs available in a given patch
release
> > > > >>>> + can run unchanged (no recompilation needed) against
the new
> > > > >>>> + jars of later patch versions.
> > > > >>>>
> > > > >>>>
> > > > >>>> What do you think?
> > > > >>>>
> > > > >>>> If these changes are (mostly) ok, then this clarifies
in one
> > > > direction.
> > > > >>>>
> > > > >>>> If these changes are not acceptable, I will propose edits
that
> > > clarify
> > > > >>>> toward the opposite meaning. ​
> > > > >>>>
> > > > >>>>
> > > > >>>>
> > > > >>>>
> > > > >>
> > > > >>
> > > >
> > > >
> > > > --
> > > > Best regards,
> > > >
> > > >    - Andy
> > > >
> > > > Problems worthy of attack prove their worth by hitting back. - Piet
> > Hein
> > > > (via Tom White)
> > > >
> > >
> >
> >
> >
> > --
> > Sean
> >
>



-- 
Sean

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