[BEAM-14545] Optimize copies in dataflow v1 shuffle reader.

[steveniemitz]

The current implementation for reading from shuffle copies byte[]s out of the larger buffer returned from reading from shuffle. This changes it to instead wrap the large buffer with ByteStrings, avoiding copying them again.

R: @lukecwik

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• Choose reviewer(s) and mention them in a comment (R: @username).
• Format the pull request title like [BEAM-XXX] Fixes bug in ApproximateQuantiles, where you replace BEAM-XXX with the appropriate JIRA issue, if applicable. This will automatically link the pull request to the issue.
• Update CHANGES.md with noteworthy changes.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI.

[asf-ci]

Can one of the admins verify this patch?

[asf-ci]

Can one of the admins verify this patch?

[codecov]

Codecov Report

Merging #17802 (45bebeb) into master (c5e521a) will decrease coverage by 0.00%.
The diff coverage is n/a.

❗ Current head 45bebeb differs from pull request most recent head d250ab2. Consider uploading reports for the commit d250ab2 to get more accurate results

@@            Coverage Diff             @@
##           master   #17802      +/-   ##
==========================================
- Coverage   73.99%   73.99%   -0.01%     
==========================================
  Files         695      703       +8     
  Lines       91829    92934    +1105     
==========================================
+ Hits        67953    68769     +816     
- Misses      22630    22899     +269     
- Partials     1246     1266      +20     

Flag	Coverage Δ
go	50.96% <ø> (+0.52%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ache_beam/runners/dataflow/dataflow_job_service.py	50.00% <0.00%> (-12.17%)	⬇️
sdks/go/pkg/beam/io/filesystem/filesystem.go	42.85% <0.00%> (-11.69%)	⬇️
...s/go/pkg/beam/core/graph/window/trigger/trigger.go	48.76% <0.00%> (-10.34%)	⬇️
...s/interactive/dataproc/dataproc_cluster_manager.py	77.41% <0.00%> (-6.80%)	⬇️
sdks/go/pkg/beam/core/metrics/store.go	10.63% <0.00%> (-4.99%)	⬇️
...eam/transforms/py_dataflow_distribution_counter.py	91.42% <0.00%> (-4.87%)	⬇️
.../apache_beam/runners/interactive/dataproc/types.py	96.55% <0.00%> (-3.45%)	⬇️
sdks/python/apache_beam/dataframe/io.py	88.78% <0.00%> (-3.26%)	⬇️
...eam/runners/portability/fn_api_runner/fn_runner.py	87.51% <0.00%> (-2.50%)	⬇️
sdks/python/apache_beam/utils/interactive_utils.py	95.12% <0.00%> (-2.44%)	⬇️
... and 102 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c5e521a...d250ab2. Read the comment docs.

[steveniemitz]

sorry for the delay on this, IntelliJ was really not cooperating recently and I kept getting sidetracked trying to make the CoderUtils change.