chore: optimize getRoomsWithSingleOwner to stop cursor iteration after assigning new owner

[abhinavkrin]

Proposed changes (including videos or screenshots)

This PR improves the performance of the getRoomsWithSingleOwner function by ensuring the cursor iteration stops immediately after a new owner is assigned.

Current Behavior

The existing implementation continues to iterate through all room members, even after assigning ownership to the oldest eligible member.
For rooms with many members, this leads to unnecessary processing and performance overhead.

Expected Behavior

Once a new owner is successfully assigned, the iteration should stop immediately.

Issue(s)

Steps to test or reproduce

Further comments

CORE-1504

Summary by CodeRabbit

• Bug Fixes
  • Improved room owner reassignment: the selection now more quickly picks a suitable replacement and stops searching once found, and it no longer skips candidates unless they are the departing user. This reduces redundant checks and speeds up ownership transfers.

[dionisio-bot]

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[changeset-bot]

⚠️ No Changeset found

Latest commit: 301815d

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[coderabbitai]

Walkthrough

The loop in getRoomsWithSingleOwner now stops iterating subscribers immediately after assigning a new owner by setting roomData.shouldChangeOwner and breaking out, and the subscriber-skip condition was narrowed to only skip when the subscriber is the target user (uid === userId).

Changes

Cohort / File(s)	Summary
Loop Optimization apps/meteor/app/lib/server/functions/getRoomsWithSingleOwner.ts	Narrowed the skip condition to uid === userId, set roomData.shouldChangeOwner = true when a new owner is chosen, and added an early break to stop subscriber iteration immediately after assignment.

Sequence Diagram(s)

sequenceDiagram
  participant Runner as getRoomsWithSingleOwner
  participant Cursor as Subscribers Cursor
  participant Member as Subscriber (uid)
  participant Room as RoomData

  Note over Runner,Cursor: Iterate subscribers
  Runner->>Cursor: fetch next member
  Cursor->>Runner: member (uid)
  alt member.uid == targetUser
    Runner->>Runner: continue (skip)
  else suitable member found
    Runner->>Room: set newOwner, roomData.shouldChangeOwner = true
    Runner-->>Cursor: break (stop iteration)
  end

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A cursor that loops without end?
Not anymore, my coding friend!
We break early when owners are set,
Fewer iterations—that's our bet!
Swift rooms now dance, no more delay.

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The PR title "chore: optimize getRoomsWithSingleOwner to stop cursor iteration after assigning new owner" is specific, concise, and directly describes the main change in the changeset. The title accurately reflects the core optimization: implementing an early exit from the loop once a new owner is successfully assigned. This aligns perfectly with the raw summary showing that the code now breaks out of the subscribers iteration after finding and assigning a new owner, rather than continuing to evaluate remaining subscribers.
Linked Issues Check	✅ Passed	The code changes in this PR directly address all objectives outlined in linked issue CORE-1504. The implementation now breaks out of the subscribers iteration immediately after assigning a new owner, which fixes the loop behavior that was previously consuming the cursor through all remaining members. The narrowed skip condition and the introduction of the break statement after newOwner assignment fulfill the requirement to stop cursor traversal once the oldest eligible member is assigned, thereby reducing unnecessary processing especially for large rooms with thousands of members.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chore/optimize-getRoomsWithSingleOwner-loop

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• apps/meteor/app/lib/server/functions/getRoomsWithSingleOwner.ts (2 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• apps/meteor/app/lib/server/functions/getRoomsWithSingleOwner.ts

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Actionable comments posted: 0

🧹 Nitpick comments (1)

apps/meteor/app/lib/server/functions/getRoomsWithSingleOwner.ts (1)

57-60: Consider breaking immediately after assignment for optimal performance.

The current implementation stops iteration after finding a new owner, which is a significant improvement. However, the break occurs on the next iteration, meaning one additional document is fetched from the cursor unnecessarily.

Apply this diff to break immediately after assigning the owner:

-					if (roomData.shouldChangeOwner) {
-						break;
-					}
-
 					const newOwner = await Users.findOneActiveById(uid, { projection: { _id: 1 } });
 					if (!newOwner) {
 						continue;
 					}
 
 					roomData.newOwner = uid;
 					roomData.shouldChangeOwner = true;
+					break;
 				}

This eliminates even that one extra cursor fetch, fully optimizing the loop termination.

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📒 Files selected for processing (1)

• apps/meteor/app/lib/server/functions/getRoomsWithSingleOwner.ts (1 hunks)

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🔇 Additional comments (1)

apps/meteor/app/lib/server/functions/getRoomsWithSingleOwner.ts (1)

54-56: LGTM! Simplified skip condition.

Correctly skips only the subscriber being removed. The separation from the shouldChangeOwner check improves clarity and sets up the early-exit optimization below.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.94%. Comparing base (9a18288) to head (301815d).
⚠️ Report is 2 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #37292      +/-   ##
===========================================
+ Coverage    66.88%   67.94%   +1.05%     
===========================================
  Files         3411     3357      -54     
  Lines       117029   114906    -2123     
  Branches     21490    20765     -725     
===========================================
- Hits         78274    78072     -202     
+ Misses       36071    34149    -1922     
- Partials      2684     2685       +1     

Flag	Coverage Δ
e2e	57.46% <ø> (ø)
unit	72.01% <ø> (+<0.01%)	⬆️

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