Here's the C++ changes

https://github.com/apache/arrow/pull/5211

I'm going to create a integration branch where we can merge each patch
before merging to master

On Fri, Aug 23, 2019 at 9:03 AM Wes McKinney <wesmck...@gmail.com> wrote:
>
> It isn't implemented in C++ yet but I will try to get a patch up for
> that soon (today maybe). I think we should create a branch where we
> can stack the patches that implement this for each language.
>
> On Fri, Aug 23, 2019 at 4:04 AM Paul Taylor <ptaylor.apa...@gmail.com> wrote:
> >
> > I'll do the JS updates. Is it safe to validate against the Arrow C++
> > integration tests?
> >
> >
> > On 8/22/19 7:28 PM, Micah Kornfield wrote:
> > > I created https://issues.apache.org/jira/browse/ARROW-6313 as a tracking
> > > issue with sub-issues on the development work.  So far no-one has claimed
> > > Java and Javascript tasks.
> > >
> > > Would it make sense to have a separate dev branch for this work?
> > >
> > > Thanks,
> > > Micah
> > >
> > > On Thu, Aug 22, 2019 at 3:24 PM Wes McKinney <wesmck...@gmail.com> wrote:
> > >
> > >> The vote carries with 4 binding +1 votes and 1 non-binding +1
> > >>
> > >> I'll merge the specification patch later today and we can begin
> > >> working on implementations so we can get this done for 0.15.0
> > >>
> > >> On Tue, Aug 20, 2019 at 12:30 PM Bryan Cutler <cutl...@gmail.com> wrote:
> > >>> +1 (non-binding)
> > >>>
> > >>> On Tue, Aug 20, 2019, 7:43 AM Antoine Pitrou <solip...@pitrou.net>
> > >> wrote:
> > >>>> Sorry, had forgotten to send my vote on this.
> > >>>>
> > >>>> +1 from me.
> > >>>>
> > >>>> Regards
> > >>>>
> > >>>> Antoine.
> > >>>>
> > >>>>
> > >>>> On Wed, 14 Aug 2019 17:42:33 -0500
> > >>>> Wes McKinney <wesmck...@gmail.com> wrote:
> > >>>>> hi all,
> > >>>>>
> > >>>>> As we've been discussing [1], there is a need to introduce 4 bytes of
> > >>>>> padding into the preamble of the "encapsulated IPC message" format to
> > >>>>> ensure that the Flatbuffers metadata payload begins on an 8-byte
> > >>>>> aligned memory offset. The alternative to this would be for Arrow
> > >>>>> implementations where alignment is important (e.g. C or C++) to copy
> > >>>>> the metadata (which is not always small) into memory when it is
> > >>>>> unaligned.
> > >>>>>
> > >>>>> Micah has proposed to address this by adding a
> > >>>>> 4-byte "continuation" value at the beginning of the payload
> > >>>>> having the value 0xFFFFFFFF. The reason to do it this way is that
> > >>>>> old clients will see an invalid length (what is currently the
> > >>>>> first 4 bytes of the message -- a 32-bit little endian signed
> > >>>>> integer indicating the metadata length) rather than potentially
> > >>>>> crashing on a valid length. We also propose to expand the "end of
> > >>>>> stream" marker used in the stream and file format from 4 to 8
> > >>>>> bytes. This has the additional effect of aligning the file footer
> > >>>>> defined in File.fbs.
> > >>>>>
> > >>>>> This would be a backwards incompatible protocol change, so older
> > >> Arrow
> > >>>>> libraries would not be able to read these new messages. Maintaining
> > >>>>> forward compatibility (reading data produced by older libraries)
> > >> would
> > >>>>> be possible as we can reason that a value other than the continuation
> > >>>>> value was produced by an older library (and then validate the
> > >>>>> Flatbuffer message of course). Arrow implementations could offer a
> > >>>>> backward compatibility mode for the sake of old readers if they
> > >> desire
> > >>>>> (this may also assist with testing).
> > >>>>>
> > >>>>> Additionally with this vote, we want to formally approve the change
> > >> to
> > >>>>> the Arrow "file" format to always write the (new 8-byte)
> > >> end-of-stream
> > >>>>> marker, which enables code that processes Arrow streams to safely
> > >> read
> > >>>>> the file's internal messages as though they were a normal stream.
> > >>>>>
> > >>>>> The PR making these changes to the IPC documentation is here
> > >>>>>
> > >>>>> https://github.com/apache/arrow/pull/4951
> > >>>>>
> > >>>>> Please vote to accept these changes. This vote will be open for at
> > >>>>> least 72 hours
> > >>>>>
> > >>>>> [ ] +1 Adopt these Arrow protocol changes
> > >>>>> [ ] +0
> > >>>>> [ ] -1 I disagree because...
> > >>>>>
> > >>>>> Here is my vote: +1
> > >>>>>
> > >>>>> Thanks,
> > >>>>> Wes
> > >>>>>
> > >>>>> [1]:
> > >> https://lists.apache.org/thread.html/8440be572c49b7b2ffb76b63e6d935ada9efd9c1c2021369b6d27786@%3Cdev.arrow.apache.org%3E
> > >>>>
> > >>>>
> > >>>>

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