Copyright	(c) The University of Glasgow 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	experimental
Portability	non-portable (concurrency)
Safe Haskell	Safe
Language	Haskell2010

Control.Concurrent.QSemN

Contents

General Quantity Semaphores

Description

Quantity semaphores in which each thread may wait for an arbitrary "amount".

Synopsis

General Quantity Semaphores

data QSemN Source

QSemN is a quantity semaphore in which the resource is aqcuired and released in units of one. 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.

newQSemN :: Int -> IO QSemN Source

Build a new QSemN with a supplied initial quantity. The initial quantity must be at least 0.

waitQSemN :: QSemN -> Int -> IO () Source

Wait for the specified quantity to become available

signalQSemN :: QSemN -> Int -> IO () Source

Signal that a given quantity is now available from the QSemN.