class Semaphore

A classic semaphore synchronization primitive.

A semaphore manages an internal counter which is decremented by each acquire() call and incremented by each release() call. The counter can never go below zero; when acquire() finds that it is zero, it blocks, waiting until some other thread calls release().

Inheritance diagram

Inheritance diagram of Semaphore

__init__(initial_count: int) → None
acquire() → None

Decrements the internal count. If the count was already at zero, blocks until the count is nonzero, then decrements it.

getCount() → int

Returns the current semaphore count. Note that this call is not thread- safe (the count may change at any time).

output(out: ostream) → None
release() → int

Increments the semaphore’s internal count. This may wake up another thread blocked on acquire().

Returns the count of the semaphore upon release.

tryAcquire() → bool

If the semaphore can be acquired without blocking, does so and returns true. Otherwise, returns false.