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{- Transactional sets
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-}
module Utility.TSet where
import Common
import Control.Concurrent.STM
type TSet = TChan
runTSet :: STM a -> IO a
runTSet = atomically
newTSet :: IO (TSet a)
newTSet = atomically newTChan
{- Gets the contents of the TSet. Blocks until at least one item is
- present. -}
getTSet :: TSet a -> IO [a]
getTSet tset = runTSet $ do
c <- readTChan tset
go [c]
where
go l = do
v <- tryReadTChan tset
case v of
Nothing -> return l
Just c -> go (c:l)
{- Puts items into a TSet. -}
putTSet :: TSet a -> [a] -> IO ()
putTSet tset vs = runTSet $ mapM_ (writeTChan tset) vs
{- Put a single item into a TSet. -}
putTSet1 :: TSet a -> a -> IO ()
putTSet1 tset v = void $ runTSet $ writeTChan tset v
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