The Library Reservation System: In a busy library, students often need to reserve study rooms in advance. To facilitate this process, the library decides to implement a reservation system using threads. The system should allow students to check room availability, reserve rooms, and cancel reservations. Question: Design a multi$-$threaded reservation system for the library. Implement functions to check room availability, reserve rooms, and cancel reservations while ensuring thread safety and proper synchronization.

Restriction: You must use mutex locks and condition variables for thread synchronization and ensure that only one thread can access or modify a room's reservation status at a time to prevent race conditions.

With this restriction in place, you'll need to carefully manage access to the shared data $($room reservation status$)$ using mutex locks to ensure thread safety. Additionally, condition variables can be used to signal when a room becomes available for reservation or when a reservation is canceled.