[yuxin00j]

Summary

Follow-up to #1102. googleapis/google-cloud-python#18641 (merged) exposes write preconditions on AsyncAppendableObjectWriter as preconditions=Preconditions(...); the if_generation_match= keyword that init_aaow passes today never shipped. This passes Preconditions(if_generation_match=N) instead, so zonal compare-and-swap writes work once that change is in a google-cloud-storage release. Older releases keep the current behavior: if_generation_match > 0 on zonal buckets raises NotImplementedError.

Changes

• gcsfs/zb_hns_utils.py:
  • Import Preconditions from google.cloud.storage.asyncio.async_appendable_object_writer, falling back to None on older releases.
  • Keep mapping if_generation_match == 0 to generation=0 so exclusive create works with every google-cloud-storage version.
  • For if_generation_match > 0, raise NotImplementedError when Preconditions is unavailable and pass preconditions=Preconditions(if_generation_match=...) otherwise.
• gcsfs/tests/test_zb_hns_utils.py, gcsfs/tests/test_core.py: update the init_aaow tests and the zonal CAS skip message.

Test plan

• pytest gcsfs/tests/test_zb_hns_utils.py gcsfs/tests/test_zonal_unit.py gcsfs/tests/test_zonal_file.py gcsfs/tests/test_zonal.py gcsfs/tests/test_retry.py gcsfs/tests/test_core.py (548 passed, 40 skipped)
• Against the merged feat(storage): add Preconditions to AsyncAppendableObjectWriter googleapis/google-cloud-python#18641: init_aaow sends WriteObjectSpec(if_generation_match=7) and WriteObjectSpec(if_generation_match=0), and maps FailedPrecondition to GenerationMismatchError.

[gemini-code-assist]

Code Review

This pull request updates the init_aaow function in gcsfs/zb_hns_utils.py to use the Preconditions class from the google-cloud-storage SDK for handling if_generation_match preconditions, rather than passing it directly as a keyword argument to AsyncAppendableObjectWriter. The unit tests have been updated to mock the Preconditions class and cover cases where the SDK does or does not support it. I have no feedback to provide as there are no review comments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.24%. Comparing base (c783299) to head (9d517c1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1131   +/-   ##
=======================================
  Coverage   92.24%   92.24%           
=======================================
  Files          20       20           
  Lines        4047     4048    +1     
=======================================
+ Hits         3733     3734    +1     
  Misses        314      314           

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