* feat: Add unit test for two level customization
issues: #49
* feat: Add class for statistic set and related unit test
issue: #49
* Initial commit of cell_update_record with unit tests.
* feat: Initial commit of cell_update_record with unit tests.
issue: #49
* Refactor code.
* Refactor code.
issue: #49
* Integrate logic with customization
issue: #49
* fix: adjust comments
issue: #49
* feat: add flag of incremental, will load previous metrix table if set to true
issues: #49
* fix: compilation in docker.
issues: #49
* fix: fix crash issue and add protection code
issues: #49
* Fix: Update code based on pull request's comments
issue: #49
* fix: Remove util/concurrent_set, directly define set in updater.hpp
issue: #49
* fix: Passing shared_ptr by reference.