2 % (c) The AQUA Project, Glasgow University, 1994-1996
5 \section[Concurrent]{Concurrent Haskell constructs}
7 A common interface to a collection of useful concurrency abstractions.
8 Currently, the collection only contains the abstractions found in the
9 {\em Concurrent Haskell} paper (presented at the Haskell Workshop
10 1995, draft available via \tr{ftp} from
11 \tr{ftp.dcs.gla.ac.uk/pub/glasgow-fp/drafts}.) plus a couple of
12 others. See the paper and the individual files containing the module
13 definitions for explanation on what they do.
24 -- Forking and suchlike
25 , forkIO -- :: IO () -> IO ThreadId
26 , myThreadId -- :: IO ThreadId
27 , killThread -- :: ThreadId -> IO ()
28 , raiseInThread -- :: ThreadId -> Exception -> IO ()
29 , par -- :: a -> b -> b
30 , seq -- :: a -> b -> b
31 , fork -- :: a -> b -> b
32 {-threadDelay, threadWaitRead, threadWaitWrite,-}
36 , newMVar -- :: a -> IO (MVar a)
37 , newEmptyMVar -- :: IO (MVar a)
38 , takeMVar -- :: MVar a -> IO a
39 , putMVar -- :: MVar a -> a -> IO ()
40 , readMVar -- :: MVar a -> IO a
41 , swapMVar -- :: MVar a -> a -> IO a
42 , isEmptyMVar -- :: MVar a -> IO Bool
45 , mergeIO -- :: [a] -> [a] -> IO [a]
46 , nmergeIO -- :: [[a]] -> IO [a]
55 import PrelHandle ( topHandler )
57 import PrelIOBase ( IO(..) )
59 import PrelAddr ( Addr )
60 import PrelArr ( ByteArray )
61 import PrelPack ( packString )
62 import PrelIOBase ( unsafePerformIO , unsafeInterleaveIO )
63 import PrelBase ( fork# )
69 forkIO :: IO () -> IO ThreadId
70 forkIO action = IO $ \ s ->
71 case (fork# action_plus s) of (# s1, id #) -> (# s1, ThreadId id #)
75 (topHandler False{-don't quit on exception raised-})
79 fork x y = unsafePerformIO (forkIO (x `seq` return ())) `seq` y
87 mergeIO :: [a] -> [a] -> IO [a]
88 nmergeIO :: [[a]] -> IO [a]
91 = newEmptyMVar >>= \ tail_node ->
92 newMVar tail_node >>= \ tail_list ->
93 newQSem max_buff_size >>= \ e ->
94 newMVar 2 >>= \ branches_running ->
98 forkIO (suckIO branches_running buff ls) >>
99 forkIO (suckIO branches_running buff rs) >>
100 takeMVar tail_node >>= \ val ->
105 = (MVar (MVar [a]), QSem)
107 suckIO :: MVar Int -> Buffer a -> [a] -> IO ()
109 suckIO branches_running buff@(tail_list,e) vs
111 [] -> takeMVar branches_running >>= \ val ->
113 takeMVar tail_list >>= \ node ->
115 putMVar tail_list node
117 putMVar branches_running (val-1)
120 takeMVar tail_list >>= \ node ->
121 newEmptyMVar >>= \ next_node ->
123 takeMVar next_node >>= \ x ->
125 return x) >>= \ next_node_val ->
126 putMVar node (x:next_node_val) >>
127 putMVar tail_list next_node >>
128 suckIO branches_running buff xs
134 newEmptyMVar >>= \ tail_node ->
135 newMVar tail_node >>= \ tail_list ->
136 newQSem max_buff_size >>= \ e ->
137 newMVar len >>= \ branches_running ->
141 mapIO (\ x -> forkIO (suckIO branches_running buff x)) lss >>
142 takeMVar tail_node >>= \ val ->
146 mapIO f xs = sequence (map f xs)