Copyright	(c) The University of Glasgow 2001
License	(c) The University of Glasgow 2001
Maintainer	libraries@haskell.org
Stability	experimental
Portability	non-portable (concurrency)
Safe Haskell	Trustworthy

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.

Instances

Typeable * QSemN

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.