DatasetDao: map JDBC driver NPE on versionSchema column read to NotFound - #3258
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DatasetDao: map JDBC driver NPE on versionSchema column read to NotFound#3258nicolaslopezbravo wants to merge 4 commits into
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In prod, GET /named/<account>/<container>/<dataset> returned HTTP 500 because mysql-connector-java 8.0.21 threw NPE from ResultSetImpl.findColumn -> getInt while reading the dataset row, and the exception bubbled past executeGetDatasetStatement uncaught. Wrap the column-read block with a narrow NPE catch and translate it to AccountServiceException(NotFound), which AccountAndContainerInjector already maps to RestServiceErrorCode.NotFound (HTTP 404). Add DatasetDaoTest covering the NPE -> NotFound mapping. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
- Narrow the NullPointerException catch in DatasetDao.executeGetDatasetStatement to only the resultSet.getInt(VERSION_SCHEMA) call (the call observed in the prod stack trace). The previous wider catch could also swallow NPEs from Jackson's objectMapper.readValue and from enum-ordinal array indexing, masking unrelated bugs as NotFound. - Add a class logger to DatasetDao and emit a warn log with account/container/ dataset identifiers when the NPE fires, so on-call has a grep target. - Add MySqlMetrics.datasetRowReadNpeCount, incremented in the catch, so the failure mode is visible on dashboards even after it surfaces as a 404. - Test: drop unused @RunWith(MockitoJUnitRunner.class), assert the exception message carries the dataset identifiers, and verify the new counter increments by 1. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…he dataset The frontend's setTargetDatasetAndVersionInRestRequestIfNeeded already emits an error log with accountName/containerName/datasetName whenever the AccountServiceException propagates up, so the warn log inside the catch just duplicates the same identifiers a layer down. The new datasetRowReadNpeCount counter is the dedicated signal for the JDBC NPE path; the existing frontend log identifies which dataset. Drop the warn log, the SLF4J Logger field, and the slf4j imports. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The fix in executeGetDatasetStatement guards only the GET dataset path, but executeGetVersionSchema makes the same resultSet.getInt(VERSION_SCHEMA) call from the version mutation paths (deleteDatasetVersion, deleteDatasetVersionForDatasetDelete, getAllValidVersionForDatasetDeletion, listAllValidDatasetVersions). The mysql-connector-java 8.0.21 NPE has not been observed there in prod, but the call shape is identical so guard it symmetrically. Reuse datasetRowReadNpeCount for the metric. Add DatasetDaoTest case driving deleteDatasetVersion to verify the same NotFound mapping and counter increment. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
A dataset GET request returned HTTP 500 in prod (2026-04-29) because mysql-connector-java 8.0.21 threw
NullPointerExceptionfromResultSetImpl.findColumn -> getIntwhile reading theversionSchemacolumn, and the exception bubbled pastexecuteGetDatasetStatementuncaught.resultSet.getInt(VERSION_SCHEMA)call with a narrowNullPointerExceptioncatch and translate it toAccountServiceException(NotFound).AccountAndContainerInjectoralready mapsAccountServiceErrorCode.NotFound->RestServiceErrorCode.NotFound(HTTP 404).executeGetVersionSchema, which makes the identical JDBC call from the version-mutation paths (deleteDatasetVersion,deleteDatasetVersionForDatasetDelete,getAllValidVersionForDatasetDeletion,listAllValidDatasetVersions). Not observed in prod on those paths, but the call shape is identical -- guard symmetrically.MySqlMetrics.datasetRowReadNpeCountso on-call can distinguish JDBC-driver NotFounds from legitimate ones on dashboards.getInt(VERSION_SCHEMA), notobjectMapper.readValueor enum-ordinal indexing) so unrelated NPEs aren't masked as NotFound.gradle/dependency-versions.gradleand asks the next person bumping mysql-connector-java to revisit.Durability Risk
Read-only / metadata-mutation paths; no blob data is at risk and no replication semantics change. Mapping a transient driver NPE to NotFound is semantically slightly off (the row exists) but the GET dataset caller (
AccountAndContainerInjector.setTargetDatasetAndVersionInRestRequestIfNeeded) does not branch on the response to do destructive create-if-missing. On the version-mutation paths, a transient NPE surfacing as NotFound is the same outcome a genuinely missing version would produce.Testing Done
DatasetDaoTest.testGetDatasetMapsJdbcNpeOnVersionSchemaToNotFound-- drivesgetDataset, asserts NotFound, identifier propagation in the exception message, anddatasetRowReadNpeCountincrement.DatasetDaoTest.testDeleteDatasetVersionMapsJdbcNpeOnVersionSchemaToNotFound-- drivesdeleteDatasetVersion, asserts the same on theexecuteGetVersionSchemapath../gradlew :ambry-account:test --tests DatasetDaoTest-- 2/2 PASSED.