fix: transaction commit fails when indexes are dropped mid-transaction

[robfrank]

Summary

• TransactionIndexContext: commit() and addFilesToLock() threw SchemaException when iterating index entries that referenced indexes dropped during the same transaction (e.g., via dropType()). Now pruned before processing.
• MCPConfiguration: isUserAllowed() threw NPE when called with a null username. Added null guard.

Test plan

• DropIndexTest.dropAndRecreateTypeWithIndex — passes (was failing)
• TruncateClassStatementExecutionTest.truncateClass — passes (was failing)
• MCPPermissionsTest.mcpNullUserNotAllowed — passes (was failing)
• All other tests in those classes still pass

🤖 Generated with Claude Code

[gemini-code-assist]

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 critical stability issues related to transaction management and user permission checks. It ensures that database transactions can commit successfully even when indexes are dropped mid-transaction, and it fortifies the user permission system against null input, thereby enhancing the overall robustness and reliability of the system.

Highlights

• Transaction Index Handling: Modified TransactionIndexContext to correctly handle index entries and file locking when indexes are dropped within the same transaction, preventing SchemaException.
• Null Username Handling: Added a null guard to MCPConfiguration.isUserAllowed() to prevent NullPointerException when a null username is provided.

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Changelog

• engine/src/main/java/com/arcadedb/database/TransactionIndexContext.java
  • Added a step in commit() to remove entries for indexes that no longer exist in the schema, preventing errors during transaction finalization.
  • Introduced a check in addFilesToLock() to skip indexes that were dropped during the transaction, avoiding attempts to lock non-existent indexes.
• server/src/main/java/com/arcadedb/server/mcp/MCPConfiguration.java
  • Implemented a null check at the beginning of isUserAllowed() to gracefully handle cases where a null username is passed, returning false instead of throwing a NullPointerException.

Activity

• Verified DropIndexTest.dropAndRecreateTypeWithIndex now passes.
• Confirmed TruncateClassStatementExecutionTest.truncateClass now passes.
• Ensured MCPPermissionsTest.mcpNullUserNotAllowed now passes.
• Validated that all other tests within the affected classes continue to pass.

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[claude]

Code Review

Good, targeted fix for two independent bugs. The changes are minimal, defensive, and well-tested. A few observations:

TransactionIndexContext — commit() (line 168)

indexEntries.keySet().removeIf(indexName -> !database.getSchema().existsIndex(indexName));

Correct placement. The prune happens before checkUniqueIndexKeys(), which calls database.getSchema().getIndexByName(...) without null/existence guards — so this ordering is load-bearing. If the order were reversed, those private methods could still throw SchemaException.

Alternative worth considering: removeIndex(String indexName) already exists (line 147) as a public method to clean up stale entries. If the schema's dropType()/dropIndex() were made to call it proactively, the defensive removeIf in commit() wouldn't be needed. That said, the current defensive approach is safe and handles cases where callers forget to do so, so it's a fine solution.

Minor: The removeIf modifies indexEntries as a side-effect of commit(). It's harmless since indexEntries.clear() is called at the end of commit() regardless, but worth being aware of.

TransactionIndexContext — addFilesToLock() (line 230)

if (!schema.existsIndex(indexName))
    continue;

Correct. Independently prevents SchemaException in this method, which is called on a separate code path from commit(). The redundancy between this guard and the removeIf in commit() is fine — addFilesToLock() may be called before commit().

MCPConfiguration — isUserAllowed() (line 174)

if (username == null)
    return false;

Correct. Without this, username.startsWith("apitoken:") at line 180 would throw NPE. Note: CopyOnWriteArrayList.contains(null) would not itself throw, so the NPE was only triggered when the wildcard check failed and execution reached the startsWith call — making it a latent bug rather than an always-crash. The fix is correct and follows the security principle of denying access on ambiguous/invalid input.

Test Coverage

All three fixes have regression tests (dropAndRecreateTypeWithIndex, TruncateClassStatementExecutionTest.truncateClass, mcpNullUserNotAllowed). The MCP test is minimal but sufficient. The dropAndRecreateTypeWithIndex test exercises the real scenario (insert records → commit → drop sub-type → continue in same transaction), which is good.

Summary

The PR is correct and well-scoped. The two bug categories (transaction lifecycle and null-safety) are unrelated but grouping minor fixes together is pragmatic. No issues blocking merge.

[gemini-code-assist]

Code Review

This pull request effectively addresses two critical issues. The TransactionIndexContext now correctly handles scenarios where indexes are dropped mid-transaction, preventing SchemaException during commit and file locking operations. Additionally, a NullPointerException in MCPConfiguration.isUserAllowed() has been resolved by adding a null check for the username parameter. These changes significantly improve the stability and robustness of the system.

[gemini-code-assist]

While the logic is correct, it is generally considered best practice in Java to always use curly braces {} with if statements, even for single-line bodies. This improves readability and prevents potential bugs if more statements are added later.

For example:

if (!schema.existsIndex(indexName)) {
  // INDEX WAS DROPPED DURING THE TRANSACTION (e.g. TYPE DROP), SKIP IT
  continue;
}

Suggested change

	if (!schema.existsIndex(indexName))
	// INDEX WAS DROPPED DURING THE TRANSACTION (e.g. TYPE DROP), SKIP IT
	continue;
	if (!schema.existsIndex(indexName)) {
	// INDEX WAS DROPPED DURING THE TRANSACTION (e.g. TYPE DROP), SKIP IT
	continue;
	}

[gemini-code-assist]

Similar to the previous comment, it's a good practice to use curly braces {} with if statements for consistency and to prevent future errors, even for single-line conditions.

For example:

if (username == null) {
  return false;
}

Suggested change

	if (username == null)
	return false;
	if (username == null) {
	return false;
	}

[mergify]

🧪 CI Insights

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[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ -8.83%	✅ 100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (4b82425)	109877	81322	74.01%
Head commit (01c2058)	140832 (+30955)	91794 (+10472)	65.18% (-8.83%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#3673)	5	5	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.73%. Comparing base (4b82425) to head (01c2058).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3673      +/-   ##
==========================================
+ Coverage   65.20%   65.73%   +0.52%     
==========================================
  Files        1550     1550              
  Lines      109877   109888      +11     
  Branches    22936    22940       +4     
==========================================
+ Hits        71645    72231     +586     
+ Misses      28581    27948     -633     
- Partials     9651     9709      +58     

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