32 Concurrency support library [thread]

Semaphores are lightweight synchronization primitives used to constrain concurrent access to a shared resource.

They are widely used to implement other synchronization primitives and, whenever both are applicable, can be more efficient than condition variables.

A counting semaphore is a semaphore object that models a non-negative resource count.

A binary semaphore is a semaphore object that has only two states.

A binary semaphore should be more efficient than the default implementation of a counting semaphore with a unit resource count.