datastore: Same key in mutation batch

[noseglid]

We flush all pending mutations then we encounter a key which already exists in the pending batch.

The indication to when a duplicate key is encountered is that we fail to insert into a HashSet. It will then proceed to flush the batch and add the current element to mutations. However, this element is not added to the unique HashSet.

This means that if there's a duplicate on the key which triggered the early flush in the next batch, that will go unnoticed and cause datastore writes to fail.

This is addressed in this commit so we always keep the HashSet populated with all pending datastore changes.

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Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a subtle bug in the Datastore writer where duplicate entity keys within a mutation batch could be missed if an early flush was triggered. The fix ensures that the internal tracking mechanism for unique keys remains accurate across batch flushes, preventing potential write failures due to undetected duplicates. A new test case has been added to specifically cover this scenario.

Highlights

• Duplicate Key Handling: Corrected an issue where duplicate keys in Datastore mutation batches were not always detected after an early flush, potentially leading to write failures.
• uniqueMutationKeys Set Update: Ensured that the uniqueMutationKeys set is consistently updated with all pending mutations, even after an intermediate batch flush, to maintain accurate tracking of unique keys.
• New Test Case: Introduced testDatastoreWriterFnWithTripleDuplicateEntities to validate the fix by asserting that commit requests do not contain multiple mutations for the same entity key, even with repeated duplicates.

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Changelog

• sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/datastore/DatastoreV1.java
  • Ensured that a key is re-added to the unique mutation keys set after a batch flush if it was the cause of the flush.
• sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/datastore/DatastoreV1Test.java
  • Added testDatastoreWriterFnWithTripleDuplicateEntities to verify correct handling of multiple duplicate keys across batches.

Activity

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