handle CloneSnapshotOp DATA RACE

[qingxinhome]

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue #16331

What this PR does / why we need it:

handle CloneSnapshotOp DATA RACE

https://github.com/matrixorigin/ci-test/actions/runs/9219842701

[matrix-meow]

@qingxinhome Thanks for your contributions!

Pull Request Review:

Title:

The title of the pull request is clear and concise, indicating that the purpose of the changes is to handle a data race in the CloneSnapshotOp function.

Body:

The body of the pull request provides relevant information about the type of PR (BUG), the specific issue it fixes (issue #16331), and the reason for the changes (to handle a data race in CloneSnapshotOp).

Changes:

1. The code snippet in the pull request shows changes made to the CloneSnapshotOp function in the operator.go file.
2. A mutex (tc.mu) is introduced to protect concurrent access to the tc.children slice.
3. The mutex is locked before appending a new op to the tc.children slice to prevent data races.
4. The mutex is unlocked immediately after the append operation to allow other goroutines to access the tc.children slice.

Feedback and Suggestions:

1. Concurrency Issue:

   • The addition of the mutex (tc.mu) is a good approach to address the data race issue. However, the locking and unlocking of the mutex should encapsulate the critical section where shared data (tc.children) is accessed or modified. In this case, the mutex should ideally be locked before accessing/modifying tc.children and unlocked after the operation is complete.
   • It's important to ensure that all accesses to tc.children are properly synchronized using the mutex to avoid potential data races.

2. Optimization:

   • Consider moving the mutex locking and unlocking closer to the critical section where tc.children is accessed. This can help reduce the time the mutex is held and minimize contention.
   • If there are other operations that access tc.children in different parts of the code, ensure they also acquire the mutex to maintain consistency.

3. Code Readability:

   • Ensure that the usage of the mutex is well-documented in the code to make it clear why it is needed and how it should be used by other developers in the future.
   • Consider adding comments to explain the purpose of the mutex and why it is necessary for synchronization.

4. Testing:

   • It would be beneficial to include tests that specifically target the concurrent access to CloneSnapshotOp and verify that the mutex effectively prevents data races.

5. Security:

   • While not directly related to the changes in this PR, it's essential to review other parts of the codebase for similar concurrency issues to ensure data integrity and prevent potential security vulnerabilities.

By addressing the concurrency issues and optimizing the use of the mutex, the codebase can be made more robust and reliable in handling concurrent operations.