chore(core): fix broadcast race condition

[NathanFlurry]

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Project	Deployment	Preview	Comments	Updated (UTC)
rivetkit-serverless	Error			Sep 18, 2025 6:10am

[NathanFlurry]

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This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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• chore(core): fix missing transport for inline tests #1287 : 2 dependent PRs (#1250 , #1289 )
• chore(core): fix test for sending message to specific connection sse race condition #1286
• fix(cloudflare-workers): fix alarms #1285
• chore(core): fix broadcast race condition #1284 👈 (View in Graphite)
• chore: list sideEffects #1283
• chore(core): fix connection tests to support sse #1282
• fix(cloudflare-workers): fix aborts on sse streams on cloudflare workers #1281
• fix(cloudflare-workers): fix aborting sse streams #1280
• chore: remove unused FakeEventSource #1279
• main

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[claude]

Claude finished @NathanFlurry's task —— View job

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Code Review Complete

Reviewing the broadcast race condition fix:

• Read and analyze the changed file
• Evaluate the race condition fix implementation
• Check for code quality and best practices
• Look for potential bugs or issues
• Assess performance and security considerations
• Provide comprehensive feedback

Analysis of Changes

The changes address a race condition in the "should receive events via broadcast" test (lines 127-134). The fix moves the event-triggering actions (setCount) inside the vi.waitFor callback to ensure proper synchronization between event subscription and event publishing in SSE (Server-Sent Events).

Changes Made:

• Moved await connection.setCount(5) and await connection.setCount(8) inside the vi.waitFor async callback
• Changed from increment to setCount operations
• Added a comment acknowledging the SSE subscription/event race condition
• Changed waitFor callback from sync to async

Code Review Feedback

✅ Positive Aspects:

1. Consistent Pattern: This fix follows the same pattern used in other tests in the file (lines 93-97, 182-185) that also address SSE race conditions
2. Proper Async Handling: Correctly made the waitFor callback async to handle the asynchronous setCount operations
3. Clear Documentation: Added a helpful comment explaining the race condition being addressed
4. Maintains Test Intent: The test still validates broadcast event functionality while fixing the timing issue

⚠️ Areas for Improvement:

1. API Inconsistency: Changed from increment() to setCount() - while this works, it changes the test's focus from testing incremental operations to absolute value setting. Consider if this affects test coverage.

2. Repeated Pattern: This is the third instance of similar race condition fixes in the same file. Consider:

   • Creating a helper function to encapsulate this pattern
   • Adding more robust synchronization mechanisms in the actual implementation
   • Documenting this as a known issue with SSE event ordering

3. Error Handling: The vi.waitFor doesn't specify timeout or interval options like other tests in the file (see lines 273-277). Consider adding explicit timeout configuration for consistency.

🐛 Potential Issues:

• Test Values: Changed from testing values 5, 8 (via increment) to 5, 8 (via setCount). This coincidentally works but could mask issues if the previous test state isn't properly reset.

🔧 Suggestions:

// Consider this more explicit pattern:
await vi.waitFor(async () => {
    await connection.setCount(5);
    await connection.setCount(8);
    expect(receivedEvents).toContain(5);
    expect(receivedEvents).toContain(8);
}, {
    timeout: 5000,
    interval: 100
});

📊 Overall Assessment:

This is a good fix that addresses a real race condition issue. The solution is consistent with other similar fixes in the codebase and properly handles the async nature of SSE event broadcasting. The main concern is the accumulation of these workarounds suggests a deeper architectural issue that might benefit from a more systematic solution.

Recommendation: ✅ Approve - This fix resolves the immediate issue and follows established patterns in the codebase.

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commit: b4196e5

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Merge activity

• Sep 24, 6:06 AM UTC: NathanFlurry added this pull request to the Graphite merge queue.
• Sep 24, 6:07 AM UTC: CI is running for this pull request on a draft pull request (#1294) due to your merge queue CI optimization settings.
• Sep 24, 6:08 AM UTC: Merged by the Graphite merge queue via draft PR: #1294.