Fix cache flush

[houjun]

Related Issues / Pull Requests

#223

Description

Add mutex protection to pointer operation to fix the race condition that may cause memory error when larger than cache max size data is transferred to the server.

What changes are proposed in this pull request?

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality not to work as expected; for instance, examples in this repository must be updated too)
• This change requires a documentation update

Checklist:

• My code modifies existing public API, or introduces new public API, and I updated or wrote docstrings
• I have commented my code
• My code requires documentation updates, and I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes