Module semaphore

Thread-safe, asynchronous counting semaphore.

A Semaphore instance holds a set of permits. Permits are used to synchronize access to a shared resource.

Before accessing the shared resource, callers acquire a permit from the semaphore. Once the permit is acquired, the caller then enters the critical section. If no permits are available, then acquiring the semaphore returns NotReady. The task is notified once a permit becomes available.

Structs

• AcquireError
  Error returned by Permit::poll_acquire.
• Permit
  A semaphore permit
• Semaphore
  Futures-aware semaphore.
• TryAcquireError
  Error returned by Permit::try_acquire.