41 lines
845 B
Haskell
41 lines
845 B
Haskell
{- Transactional sets
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-
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- Copyright 2012, 2013 Joey Hess <joey@kitenet.net>
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-}
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module Utility.TSet where
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import Common
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import Control.Concurrent.STM
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type TSet = TChan
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newTSet :: STM (TSet a)
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newTSet = newTChan
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{- Gets the contents of the TSet. Blocks until at least one item is
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- present. -}
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getTSet :: TSet a -> STM [a]
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getTSet tset = do
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c <- readTChan tset
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l <- readTSet tset
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return $ c:l
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{- Gets anything currently in the TSet, without blocking. -}
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readTSet :: TSet a -> STM [a]
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readTSet tset = go []
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where
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go l = do
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v <- tryReadTChan tset
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case v of
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Nothing -> return l
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Just c -> go (c:l)
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{- Puts items into a TSet. -}
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putTSet :: TSet a -> [a] -> STM ()
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putTSet tset vs = mapM_ (writeTChan tset) vs
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{- Put a single item into a TSet. -}
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putTSet1 :: TSet a -> a -> STM ()
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putTSet1 tset v = void $ writeTChan tset v
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