[serve][SessionManager] Rename a variable based on the class name.
[server][SessionManager] Add a timeout mechanism.
[server][SessionManager] Make this class MT-safe.
[server][SessionManager] Write a more specific reason.
[server][SessionManager] Use a constant: NO_TIMEOUT instead of a raw number: 0.
[server][testSessionManager] Rename a variable to improve readability by specifying itself..

instance ->
sessionMgr
[server][SessionManager] Remove an assertion that is not directly related with the test case.
[server][SessionManager] Add a new test: test_createWithoutTimeout().
[mlpl][SmartTime] Implement a copy constructor.
[server][testSessionManager] Add a new test: test_update().