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
34 {-threadDelay, threadWaitRead, threadWaitWrite,-}
38 , newMVar -- :: a -> IO (MVar a)
39 , newEmptyMVar -- :: IO (MVar a)
40 , takeMVar -- :: MVar a -> IO a
41 , putMVar -- :: MVar a -> a -> IO ()
42 , readMVar -- :: MVar a -> IO a
43 , swapMVar -- :: MVar a -> a -> IO a
44 , isEmptyMVar -- :: MVar a -> IO Bool
47 , mergeIO -- :: [a] -> [a] -> IO [a]
48 , nmergeIO -- :: [[a]] -> IO [a]
57 import PrelHandle ( topHandler )
59 import PrelIOBase ( IO(..) )
61 import PrelAddr ( Addr )
62 import PrelArr ( ByteArray )
63 import PrelPack ( packString )
64 import PrelIOBase ( unsafePerformIO , unsafeInterleaveIO )
65 import PrelBase ( fork# )
66 import PrelGHC ( Addr#, unsafeCoerce# )
71 Thread Ids, specifically the instances of Eq and Ord for these things.
72 The ThreadId type itself is defined in std/PrelConc.lhs.
74 Rather than define a new primitve, we use a little helper function
75 cmp_thread in the RTS.
78 foreign import ccall "cmp_thread" unsafe cmp_thread :: Addr# -> Addr# -> Int
81 cmpThread :: ThreadId -> ThreadId -> Ordering
82 cmpThread (ThreadId t1) (ThreadId t2) =
83 case cmp_thread (unsafeCoerce# t1) (unsafeCoerce# t2) of
88 instance Eq ThreadId where
90 case t1 `cmpThread` t2 of
94 instance Ord ThreadId where
99 forkIO :: IO () -> IO ThreadId
100 forkIO action = IO $ \ s ->
101 case (fork# action_plus s) of (# s1, id #) -> (# s1, ThreadId id #)
104 catchException action
105 (topHandler False{-don't quit on exception raised-})
109 fork x y = unsafePerformIO (forkIO (x `seq` return ())) `seq` y
117 mergeIO :: [a] -> [a] -> IO [a]
118 nmergeIO :: [[a]] -> IO [a]
121 = newEmptyMVar >>= \ tail_node ->
122 newMVar tail_node >>= \ tail_list ->
123 newQSem max_buff_size >>= \ e ->
124 newMVar 2 >>= \ branches_running ->
128 forkIO (suckIO branches_running buff ls) >>
129 forkIO (suckIO branches_running buff rs) >>
130 takeMVar tail_node >>= \ val ->
135 = (MVar (MVar [a]), QSem)
137 suckIO :: MVar Int -> Buffer a -> [a] -> IO ()
139 suckIO branches_running buff@(tail_list,e) vs
141 [] -> takeMVar branches_running >>= \ val ->
143 takeMVar tail_list >>= \ node ->
145 putMVar tail_list node
147 putMVar branches_running (val-1)
150 takeMVar tail_list >>= \ node ->
151 newEmptyMVar >>= \ next_node ->
153 takeMVar next_node >>= \ x ->
155 return x) >>= \ next_node_val ->
156 putMVar node (x:next_node_val) >>
157 putMVar tail_list next_node >>
158 suckIO branches_running buff xs
164 newEmptyMVar >>= \ tail_node ->
165 newMVar tail_node >>= \ tail_list ->
166 newQSem max_buff_size >>= \ e ->
167 newMVar len >>= \ branches_running ->
171 mapIO (\ x -> forkIO (suckIO branches_running buff x)) lss >>
172 takeMVar tail_node >>= \ val ->
176 mapIO f xs = sequence (map f xs)