ARROW-17836: [C++] Allow specifying alignment of buffers

[save-buffer]

[github-actions[bot]]

https://issues.apache.org/jira/browse/ARROW-17836

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[save-buffer]

Seems like the only CI issue is

`actual$x`:   "2018-10-07T19:04:05" NA
[24011](https://github.com/apache/arrow/actions/runs/3147572706/jobs/5117455486#step:11:24012)
`expected$x`: "2018-10-07 19:04:05" NA
[24012](https://github.com/apache/arrow/actions/runs/3147572706/jobs/5117455486#step:11:24013)

I see this issue on some other PRs and also I don't touch this test at all in my code, so I think this is fine.

[save-buffer]

Rebasing, the R errors are gone but the scanner test seems to be failing:

terminate called after throwing an instance of 'std::system_error'
[263](https://github.com/apache/arrow/actions/runs/3176058214/jobs/5174896904#step:11:264)
  what():  Resource temporarily unavailable
[264](https://github.com/apache/arrow/actions/runs/3176058214/jobs/5174896904#step:11:265)
terminate called recursively
[265](https://github.com/apache/arrow/actions/runs/3176058214/jobs/5174896904#step:11:266)

Again, probably not me. I'd guess related to Weston's scanner refactor.

[pitrou]

@westonpace ^^

[pitrou]

Also opened https://issues.apache.org/jira/browse/ARROW-17927 for a similar issue on scanner tests.

[pitrou]

@save-buffer I added some tests for the random array generator and it turns out that list arrays may not end up aligned due to ListArray::FromArrays. That can be for a later PR though. What do you think?

[pitrou]

@github-actions crossbow submit -g cpp

[github-actions[bot]]

Revision: 3948cb21109ce715fd83fb762f63833805f8e009

Submitted crossbow builds: ursacomputing/crossbow @ actions-0ee166c579

Task	Status
test-alpine-linux-cpp
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-cuda-cpp
test-debian-10-cpp-amd64
test-debian-10-cpp-i386
test-debian-11-cpp-amd64
test-debian-11-cpp-i386
test-fedora-35-cpp
test-ubuntu-18.04-cpp
test-ubuntu-18.04-cpp-release
test-ubuntu-18.04-cpp-static
test-ubuntu-20.04-cpp
test-ubuntu-20.04-cpp-20
test-ubuntu-20.04-cpp-bundled
test-ubuntu-20.04-cpp-thread-sanitizer
test-ubuntu-22.04-cpp

[save-buffer]

Thanks for adding those, yes I agree this PR is big enough for now. Adding support for Lists the issue is that the buffers passed in may not be aligned, right? This may be more convenient to do after we have a utility that will reallocate/copy to a specific alignment if needed (I think Sanjiban is working on something like that?)

[sanjibansg]

Thanks for adding those, yes I agree this PR is big enough for now. Adding support for Lists the issue is that the buffers passed in may not be aligned, right? This may be more convenient to do after we have a utility that will reallocate/copy to a specific alignment if needed (I think Sanjiban is working on something like that?)

Yes, I already have that utility ready. I am waiting for this PR to get merged and I will then make a PR for ensuring alignment.

[pitrou]

Adding support for Lists the issue is that the buffers passed in may not be aligned, right?

No, it's just that random generation for lists calls ListArray::FromArrays, which can allocate new buffers in some cases, and that method doesn't take the alignment parameter yet.

[ursabot]

Benchmark runs are scheduled for baseline = 63f013cdb36d05f6f96a145aff3c6232470f2d02 and contender = 2078af7c710d688c14313b9486b99c981550a7b7. 2078af7c710d688c14313b9486b99c981550a7b7 is a master commit associated with this PR. Results will be available as each benchmark for each run completes. Conbench compare runs links: [Finished :arrow_down:0.0% :arrow_up:0.0%] ec2-t3-xlarge-us-east-2 [Finished :arrow_down:0.84% :arrow_up:0.57%] test-mac-arm [Finished :arrow_down:0.82% :arrow_up:0.0%] ursa-i9-9960x [Finished :arrow_down:1.12% :arrow_up:0.98%] ursa-thinkcentre-m75q Buildkite builds: [Finished] 2078af7c ec2-t3-xlarge-us-east-2 [Finished] 2078af7c test-mac-arm [Finished] 2078af7c ursa-i9-9960x [Finished] 2078af7c ursa-thinkcentre-m75q [Finished] 63f013cd ec2-t3-xlarge-us-east-2 [Finished] 63f013cd test-mac-arm [Finished] 63f013cd ursa-i9-9960x [Finished] 63f013cd ursa-thinkcentre-m75q Supported benchmarks: ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True test-mac-arm: Supported benchmark langs: C++, Python, R ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java