UnliftIO.QSemN

QSemN is a quantity semaphore in which the resource is acquired and released in arbitrary amounts. It provides guaranteed FIFO ordering for satisfying blocked waitQSemN calls.

The pattern

bracket_ (waitQSemN n) (signalQSemN n) (...)

is safe; it never loses any of the resource.

Lifted newQSemN.

Lifted waitQSemN.

Lifted signalQSemN.

withQSemN is an exception-safe wrapper for performing the provided operation while holding N unit of value from the semaphore. It ensures the semaphore cannot be leaked if there are exceptions.