• Problem Conditions:
  • 1 waiting room with N chairs.
  • 1 barber room with 1 barber chair
• Barber and Customers
  • If there is no customers, the barber goes to sleep.
  • If a customer enters the shop
  • If all chairs are occupied, the customer leaves.
  • If the barber is busy and chairs are available, the customer sits in one of the free chairs.
  • If the barber is asleep, the customer wakes up the barber.

This solution uses three semaphores:

• chairs_mutex: A mutex to access chair count thread-safely.
• sem_client: Signal that a customer is ready.
• sem_barber: Check if barber is idle.