Fix hang for TestCTE.Concurrent test

[xzhangxian1008]

What problem does this PR solve?

Issue Number: close #10636

Problem Summary:

What is changed and how it works?

In `waitForBlockAvailableForTest`, CTEReader will wait the wake of `cv_for_test`. However, we need to check if there are any available blocks before entering the wait or it will wait forever when there is no more block to be pushed.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix the issue that TestCTE.Concurrent may hang forever

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[coderabbitai]

📝 Walkthrough

Walkthrough

The pull request refactors synchronization primitives in the CTE (Common Table Expression) operator to prevent deadlocks. A shared read-write lock replaces per-partition mutexes for protecting a broader set of state variables. Lock acquisition order is carefully adjusted during blocking waits to avoid circular wait conditions.

Changes

Cohort / File(s)	Summary
Synchronization primitive refactoring dbms/src/Operators/CTE.h	Added public getRWLockForTest() accessor and private std::shared_mutex rw_lock field to protect multiple state variables (next_cte_reader_id, is_eof, is_cancelled, get_resp, resp, err_msg, sink_exit_num, source_exit_num, registered_sink_num). Removed per-partition test mutex initialization.
Partition test mutex removal dbms/src/Operators/CTEPartition.h	Removed mu_for_test public member field (unique_ptrstd::mutex) from struct. Other synchronization primitives (mu, cv_for_test) retained.
Lock acquisition pattern updates dbms/src/Operators/CTEReader.cpp	Updated to use shared rw-lock from CTE with careful lock ordering during blocking waits. Replaced checkBlockAvailable call with checkBlockAvailableNoLock to avoid holding partition lock during availability checks. Adjusted waiting loop to release rw-lock before condition variable wait, then re-acquire locks in deadlock-safe order.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested labels

approved, lgtm

Suggested reviewers

• JaySon-Huang
• wshwsh12
• JinheLin

Poem

🐰 A lock for each partition caused a tangled mess,
But shared mutexes bring harmony and blessed access,
TSAN's complaints fade as deadlocks take their final bow,
CTE's symphony plays in perfect order now! 🎼

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ 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%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main objective of the PR: fixing a hang issue in the TestCTE.Concurrent test.
Linked Issues check	✅ Passed	The PR addresses the hang issue in TestCTE.Concurrent by implementing synchronization mechanism improvements: replacing per-partition mutex with shared read-write lock in CTE, and adjusting lock acquisition/release patterns to prevent deadlocks.
Out of Scope Changes check	✅ Passed	All code changes (CTE.h, CTEPartition.h, CTEReader.cpp) directly relate to fixing the TestCTE.Concurrent hang issue through improved synchronization logic, with no unrelated modifications detected.
Description check	✅ Passed	The PR description follows the template with all required sections completed, including issue reference, problem summary, code changes explanation, test checklist, side effects assessment, and release note.

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✨ Finishing touches

• 📝 Generate docstrings

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[xzhangxian1008]

/cc @windtalker @gengliqi

[xzhangxian1008]

/run-check-issue-triage-complete

[gengliqi]

How about using a reference instead of a pointer?

[gengliqi]

Maybe add a sleep above this line of code?