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Remove Control.Parallel*, now in package parallel
[haskell-directory.git]
/
Control
/
Concurrent
/
QSem.hs
diff --git
a/Control/Concurrent/QSem.hs
b/Control/Concurrent/QSem.hs
index
04064e4
..
5a512d8
100644
(file)
--- a/
Control/Concurrent/QSem.hs
+++ b/
Control/Concurrent/QSem.hs
@@
-6,14
+6,15
@@
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
--- Portability : non-portable
+-- Portability : non-portable (concurrency)
--
--
--- General semaphores
+-- Simple quantity semaphores.
--
-----------------------------------------------------------------------------
module Control.Concurrent.QSem
--
-----------------------------------------------------------------------------
module Control.Concurrent.QSem
- ( QSem, -- abstract
+ ( -- * Simple Quantity Semaphores
+ QSem, -- abstract
newQSem, -- :: Int -> IO QSem
waitQSem, -- :: QSem -> IO ()
signalQSem -- :: QSem -> IO ()
newQSem, -- :: Int -> IO QSem
waitQSem, -- :: QSem -> IO ()
signalQSem -- :: QSem -> IO ()
@@
-21,6
+22,9
@@
module Control.Concurrent.QSem
import Prelude
import Control.Concurrent.MVar
import Prelude
import Control.Concurrent.MVar
+import Data.Typeable
+
+#include "Typeable.h"
-- General semaphores are also implemented readily in terms of shared
-- @MVar@s, only have to catch the case when the semaphore is tried
-- General semaphores are also implemented readily in terms of shared
-- @MVar@s, only have to catch the case when the semaphore is tried
@@
-29,13
+33,19
@@
import Control.Concurrent.MVar
-- representing threads currently waiting. The counter is a shared
-- variable, ensuring the mutual exclusion on its access.
-- representing threads currently waiting. The counter is a shared
-- variable, ensuring the mutual exclusion on its access.
+-- |A 'QSem' is a simple quantity semaphore, in which the available
+-- \"quantity\" is always dealt with in units of one.
newtype QSem = QSem (MVar (Int, [MVar ()]))
newtype QSem = QSem (MVar (Int, [MVar ()]))
+INSTANCE_TYPEABLE0(QSem,qSemTc,"QSem")
+
+-- |Build a new 'QSem'
newQSem :: Int -> IO QSem
newQSem init = do
sem <- newMVar (init,[])
return (QSem sem)
newQSem :: Int -> IO QSem
newQSem init = do
sem <- newMVar (init,[])
return (QSem sem)
+-- |Wait for a unit to become available
waitQSem :: QSem -> IO ()
waitQSem (QSem sem) = do
(avail,blocked) <- takeMVar sem -- gain ex. access
waitQSem :: QSem -> IO ()
waitQSem (QSem sem) = do
(avail,blocked) <- takeMVar sem -- gain ex. access
@@
-55,6
+65,7
@@
waitQSem (QSem sem) = do
putMVar sem (0, blocked++[block])
takeMVar block
putMVar sem (0, blocked++[block])
takeMVar block
+-- |Signal that a unit of the 'QSem' is available
signalQSem :: QSem -> IO ()
signalQSem (QSem sem) = do
(avail,blocked) <- takeMVar sem
signalQSem :: QSem -> IO ()
signalQSem (QSem sem) = do
(avail,blocked) <- takeMVar sem