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|
-----------------------------------------------------------------------------
-- |
-- Module : Control.Concurrent
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
-- Portability : non-portable
--
-- A common interface to a collection of useful concurrency
-- abstractions.
--
-----------------------------------------------------------------------------
module Control.Concurrent (
module Control.Concurrent.Chan,
module Control.Concurrent.CVar,
module Control.Concurrent.MVar,
module Control.Concurrent.QSem,
module Control.Concurrent.QSemN,
module Control.Concurrent.SampleVar,
forkIO, -- :: IO () -> IO ()
yield, -- :: IO ()
#ifdef __GLASGOW_HASKELL__
ThreadId,
-- Forking and suchlike
myThreadId, -- :: IO ThreadId
killThread, -- :: ThreadId -> IO ()
throwTo, -- :: ThreadId -> Exception -> IO ()
threadDelay, -- :: Int -> IO ()
threadWaitRead, -- :: Int -> IO ()
threadWaitWrite, -- :: Int -> IO ()
#endif
-- merging of streams
mergeIO, -- :: [a] -> [a] -> IO [a]
nmergeIO -- :: [[a]] -> IO [a]
) where
import Prelude
import Control.Exception as Exception
#ifdef __GLASGOW_HASKELL__
import GHC.Conc
import GHC.TopHandler ( reportStackOverflow, reportError )
import GHC.IOBase ( IO(..) )
import GHC.IOBase ( unsafeInterleaveIO )
import GHC.Base
#endif
#ifdef __HUGS__
import IOExts ( unsafeInterleaveIO )
import ConcBase
#endif
import Control.Concurrent.MVar
import Control.Concurrent.CVar
import Control.Concurrent.Chan
import Control.Concurrent.QSem
import Control.Concurrent.QSemN
import Control.Concurrent.SampleVar
-- Thread Ids, specifically the instances of Eq and Ord for these things.
-- The ThreadId type itself is defined in std/PrelConc.lhs.
-- Rather than define a new primitve, we use a little helper function
-- cmp_thread in the RTS.
#ifdef __GLASGOW_HASKELL__
foreign import ccall unsafe "cmp_thread" cmp_thread :: Addr# -> Addr# -> Int
-- Returns -1, 0, 1
cmpThread :: ThreadId -> ThreadId -> Ordering
cmpThread (ThreadId t1) (ThreadId t2) =
case cmp_thread (unsafeCoerce# t1) (unsafeCoerce# t2) of
-1 -> LT
0 -> EQ
_ -> GT -- must be 1
instance Eq ThreadId where
t1 == t2 =
case t1 `cmpThread` t2 of
EQ -> True
_ -> False
instance Ord ThreadId where
compare = cmpThread
foreign import ccall unsafe "rts_getThreadId" getThreadId :: Addr# -> Int
instance Show ThreadId where
showsPrec d (ThreadId t) =
showString "ThreadId " .
showsPrec d (getThreadId (unsafeCoerce# t))
forkIO :: IO () -> IO ThreadId
forkIO action = IO $ \ s ->
case (fork# action_plus s) of (# s1, id #) -> (# s1, ThreadId id #)
where
action_plus = Exception.catch action childHandler
childHandler :: Exception -> IO ()
childHandler err = Exception.catch (real_handler err) childHandler
real_handler :: Exception -> IO ()
real_handler ex =
case ex of
-- ignore thread GC and killThread exceptions:
BlockedOnDeadMVar -> return ()
AsyncException ThreadKilled -> return ()
-- report all others:
AsyncException StackOverflow -> reportStackOverflow False
ErrorCall s -> reportError False s
other -> reportError False (showsPrec 0 other "\n")
#endif /* __GLASGOW_HASKELL__ */
max_buff_size :: Int
max_buff_size = 1
mergeIO :: [a] -> [a] -> IO [a]
nmergeIO :: [[a]] -> IO [a]
mergeIO ls rs
= newEmptyMVar >>= \ tail_node ->
newMVar tail_node >>= \ tail_list ->
newQSem max_buff_size >>= \ e ->
newMVar 2 >>= \ branches_running ->
let
buff = (tail_list,e)
in
forkIO (suckIO branches_running buff ls) >>
forkIO (suckIO branches_running buff rs) >>
takeMVar tail_node >>= \ val ->
signalQSem e >>
return val
type Buffer a
= (MVar (MVar [a]), QSem)
suckIO :: MVar Int -> Buffer a -> [a] -> IO ()
suckIO branches_running buff@(tail_list,e) vs
= case vs of
[] -> takeMVar branches_running >>= \ val ->
if val == 1 then
takeMVar tail_list >>= \ node ->
putMVar node [] >>
putMVar tail_list node
else
putMVar branches_running (val-1)
(x:xs) ->
waitQSem e >>
takeMVar tail_list >>= \ node ->
newEmptyMVar >>= \ next_node ->
unsafeInterleaveIO (
takeMVar next_node >>= \ y ->
signalQSem e >>
return y) >>= \ next_node_val ->
putMVar node (x:next_node_val) >>
putMVar tail_list next_node >>
suckIO branches_running buff xs
nmergeIO lss
= let
len = length lss
in
newEmptyMVar >>= \ tail_node ->
newMVar tail_node >>= \ tail_list ->
newQSem max_buff_size >>= \ e ->
newMVar len >>= \ branches_running ->
let
buff = (tail_list,e)
in
mapIO (\ x -> forkIO (suckIO branches_running buff x)) lss >>
takeMVar tail_node >>= \ val ->
signalQSem e >>
return val
where
mapIO f xs = sequence (map f xs)
|
