2 {-# OPTIONS_GHC -fno-implicit-prelude #-}
3 -----------------------------------------------------------------------------
6 -- Copyright : (c) The University of Glasgow, 1994-2002
7 -- License : see libraries/base/LICENSE
9 -- Maintainer : cvs-ghc@haskell.org
10 -- Stability : internal
11 -- Portability : non-portable (GHC extensions)
13 -- Basic concurrency stuff.
15 -----------------------------------------------------------------------------
20 -- Forking and suchlike
21 , myThreadId -- :: IO ThreadId
22 , killThread -- :: ThreadId -> IO ()
23 , throwTo -- :: ThreadId -> Exception -> IO ()
24 , par -- :: a -> b -> b
25 , pseq -- :: a -> b -> b
27 , labelThread -- :: ThreadId -> String -> IO ()
30 , threadDelay -- :: Int -> IO ()
31 , threadWaitRead -- :: Int -> IO ()
32 , threadWaitWrite -- :: Int -> IO ()
36 , newMVar -- :: a -> IO (MVar a)
37 , newEmptyMVar -- :: IO (MVar a)
38 , takeMVar -- :: MVar a -> IO a
39 , putMVar -- :: MVar a -> a -> IO ()
40 , tryTakeMVar -- :: MVar a -> IO (Maybe a)
41 , tryPutMVar -- :: MVar a -> a -> IO Bool
42 , isEmptyMVar -- :: MVar a -> IO Bool
43 , addMVarFinalizer -- :: MVar a -> IO () -> IO ()
47 , atomically -- :: STM a -> IO a
49 , orElse -- :: STM a -> STM a -> STM a
50 , catchSTM -- :: STM a -> (Exception -> STM a) -> STM a
52 , newTVar -- :: a -> STM (TVar a)
53 , readTVar -- :: TVar a -> STM a
54 , writeTVar -- :: a -> TVar a -> STM ()
55 , unsafeIOToSTM -- :: IO a -> STM a
57 #ifdef mingw32_HOST_OS
58 , asyncRead -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
59 , asyncWrite -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
60 , asyncDoProc -- :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
62 , asyncReadBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
63 , asyncWriteBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
67 import System.Posix.Types
68 import System.Posix.Internals
76 import GHC.Num ( Num(..) )
77 import GHC.Real ( fromIntegral, quot )
78 import GHC.Base ( Int(..) )
79 import GHC.Exception ( Exception(..), AsyncException(..) )
80 import GHC.Pack ( packCString# )
81 import GHC.Ptr ( Ptr(..), plusPtr, FunPtr(..) )
86 infixr 0 `par`, `pseq`
89 %************************************************************************
91 \subsection{@ThreadId@, @par@, and @fork@}
93 %************************************************************************
96 data ThreadId = ThreadId ThreadId#
97 -- ToDo: data ThreadId = ThreadId (Weak ThreadId#)
98 -- But since ThreadId# is unlifted, the Weak type must use open
101 A 'ThreadId' is an abstract type representing a handle to a thread.
102 'ThreadId' is an instance of 'Eq', 'Ord' and 'Show', where
103 the 'Ord' instance implements an arbitrary total ordering over
104 'ThreadId's. The 'Show' instance lets you convert an arbitrary-valued
105 'ThreadId' to string form; showing a 'ThreadId' value is occasionally
106 useful when debugging or diagnosing the behaviour of a concurrent
109 /Note/: in GHC, if you have a 'ThreadId', you essentially have
110 a pointer to the thread itself. This means the thread itself can\'t be
111 garbage collected until you drop the 'ThreadId'.
112 This misfeature will hopefully be corrected at a later date.
114 /Note/: Hugs does not provide any operations on other threads;
115 it defines 'ThreadId' as a synonym for ().
118 INSTANCE_TYPEABLE0(ThreadId,threadIdTc,"ThreadId")
121 --forkIO has now been hoisted out into the Concurrent library.
123 {- | 'killThread' terminates the given thread (GHC only).
124 Any work already done by the thread isn\'t
125 lost: the computation is suspended until required by another thread.
126 The memory used by the thread will be garbage collected if it isn\'t
127 referenced from anywhere. The 'killThread' function is defined in
130 > killThread tid = throwTo tid (AsyncException ThreadKilled)
133 killThread :: ThreadId -> IO ()
134 killThread tid = throwTo tid (AsyncException ThreadKilled)
136 {- | 'throwTo' raises an arbitrary exception in the target thread (GHC only).
138 'throwTo' does not return until the exception has been raised in the
139 target thread. The calling thread can thus be certain that the target
140 thread has received the exception. This is a useful property to know
141 when dealing with race conditions: eg. if there are two threads that
142 can kill each other, it is guaranteed that only one of the threads
143 will get to kill the other. -}
144 throwTo :: ThreadId -> Exception -> IO ()
145 throwTo (ThreadId id) ex = IO $ \ s ->
146 case (killThread# id ex s) of s1 -> (# s1, () #)
148 -- | Returns the 'ThreadId' of the calling thread (GHC only).
149 myThreadId :: IO ThreadId
150 myThreadId = IO $ \s ->
151 case (myThreadId# s) of (# s1, id #) -> (# s1, ThreadId id #)
154 -- |The 'yield' action allows (forces, in a co-operative multitasking
155 -- implementation) a context-switch to any other currently runnable
156 -- threads (if any), and is occasionally useful when implementing
157 -- concurrency abstractions.
160 case (yield# s) of s1 -> (# s1, () #)
162 {- | 'labelThread' stores a string as identifier for this thread if
163 you built a RTS with debugging support. This identifier will be used in
164 the debugging output to make distinction of different threads easier
165 (otherwise you only have the thread state object\'s address in the heap).
167 Other applications like the graphical Concurrent Haskell Debugger
168 (<http://www.informatik.uni-kiel.de/~fhu/chd/>) may choose to overload
169 'labelThread' for their purposes as well.
172 labelThread :: ThreadId -> String -> IO ()
173 labelThread (ThreadId t) str = IO $ \ s ->
174 let ps = packCString# str
175 adr = byteArrayContents# ps in
176 case (labelThread# t adr s) of s1 -> (# s1, () #)
178 -- Nota Bene: 'pseq' used to be 'seq'
179 -- but 'seq' is now defined in PrelGHC
181 -- "pseq" is defined a bit weirdly (see below)
183 -- The reason for the strange "lazy" call is that
184 -- it fools the compiler into thinking that pseq and par are non-strict in
185 -- their second argument (even if it inlines pseq at the call site).
186 -- If it thinks pseq is strict in "y", then it often evaluates
187 -- "y" before "x", which is totally wrong.
191 pseq x y = x `seq` lazy y
195 par x y = case (par# x) of { _ -> lazy y }
199 %************************************************************************
201 \subsection[stm]{Transactional heap operations}
203 %************************************************************************
205 TVars are shared memory locations which support atomic memory
209 newtype STM a = STM (State# RealWorld -> (# State# RealWorld, a #))
211 INSTANCE_TYPEABLE1(STM,stmTc,"STM" )
213 unSTM :: STM a -> (State# RealWorld -> (# State# RealWorld, a #))
216 instance Functor STM where
217 fmap f x = x >>= (return . f)
219 instance Monad STM where
220 {-# INLINE return #-}
224 return x = returnSTM x
225 m >>= k = bindSTM m k
227 bindSTM :: STM a -> (a -> STM b) -> STM b
228 bindSTM (STM m) k = STM ( \s ->
230 (# new_s, a #) -> unSTM (k a) new_s
233 thenSTM :: STM a -> STM b -> STM b
234 thenSTM (STM m) k = STM ( \s ->
236 (# new_s, a #) -> unSTM k new_s
239 returnSTM :: a -> STM a
240 returnSTM x = STM (\s -> (# s, x #))
242 -- | Unsafely performs IO in the STM monad.
243 unsafeIOToSTM :: IO a -> STM a
244 unsafeIOToSTM (IO m) = STM m
246 -- |Perform a series of STM actions atomically.
247 atomically :: STM a -> IO a
248 atomically (STM m) = IO (\s -> (atomically# m) s )
250 -- |Retry execution of the current memory transaction because it has seen
251 -- values in TVars which mean that it should not continue (e.g. the TVars
252 -- represent a shared buffer that is now empty). The implementation may
253 -- block the thread until one of the TVars that it has read from has been
256 retry = STM $ \s# -> retry# s#
258 -- |Compose two alternative STM actions. If the first action completes without
259 -- retrying then it forms the result of the orElse. Otherwise, if the first
260 -- action retries, then the second action is tried in its place. If both actions
261 -- retry then the orElse as a whole retries.
262 orElse :: STM a -> STM a -> STM a
263 orElse (STM m) e = STM $ \s -> catchRetry# m (unSTM e) s
265 -- |Exception handling within STM actions.
266 catchSTM :: STM a -> (Exception -> STM a) -> STM a
267 catchSTM (STM m) k = STM $ \s -> catchSTM# m (\ex -> unSTM (k ex)) s
269 data TVar a = TVar (TVar# RealWorld a)
271 INSTANCE_TYPEABLE1(TVar,tvarTc,"TVar" )
273 instance Eq (TVar a) where
274 (TVar tvar1#) == (TVar tvar2#) = sameTVar# tvar1# tvar2#
276 -- |Create a new TVar holding a value supplied
277 newTVar :: a -> STM (TVar a)
278 newTVar val = STM $ \s1# ->
279 case newTVar# val s1# of
280 (# s2#, tvar# #) -> (# s2#, TVar tvar# #)
282 -- |Return the current value stored in a TVar
283 readTVar :: TVar a -> STM a
284 readTVar (TVar tvar#) = STM $ \s# -> readTVar# tvar# s#
286 -- |Write the supplied value into a TVar
287 writeTVar :: TVar a -> a -> STM ()
288 writeTVar (TVar tvar#) val = STM $ \s1# ->
289 case writeTVar# tvar# val s1# of
294 %************************************************************************
296 \subsection[mvars]{M-Structures}
298 %************************************************************************
300 M-Vars are rendezvous points for concurrent threads. They begin
301 empty, and any attempt to read an empty M-Var blocks. When an M-Var
302 is written, a single blocked thread may be freed. Reading an M-Var
303 toggles its state from full back to empty. Therefore, any value
304 written to an M-Var may only be read once. Multiple reads and writes
305 are allowed, but there must be at least one read between any two
309 --Defined in IOBase to avoid cycle: data MVar a = MVar (SynchVar# RealWorld a)
311 INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
313 -- |Create an 'MVar' which is initially empty.
314 newEmptyMVar :: IO (MVar a)
315 newEmptyMVar = IO $ \ s# ->
317 (# s2#, svar# #) -> (# s2#, MVar svar# #)
319 -- |Create an 'MVar' which contains the supplied value.
320 newMVar :: a -> IO (MVar a)
322 newEmptyMVar >>= \ mvar ->
323 putMVar mvar value >>
326 -- |Return the contents of the 'MVar'. If the 'MVar' is currently
327 -- empty, 'takeMVar' will wait until it is full. After a 'takeMVar',
328 -- the 'MVar' is left empty.
330 -- If several threads are competing to take the same 'MVar', one is chosen
331 -- to continue at random when the 'MVar' becomes full.
332 takeMVar :: MVar a -> IO a
333 takeMVar (MVar mvar#) = IO $ \ s# -> takeMVar# mvar# s#
335 -- |Put a value into an 'MVar'. If the 'MVar' is currently full,
336 -- 'putMVar' will wait until it becomes empty.
338 -- If several threads are competing to fill the same 'MVar', one is
339 -- chosen to continue at random when the 'MVar' becomes empty.
340 putMVar :: MVar a -> a -> IO ()
341 putMVar (MVar mvar#) x = IO $ \ s# ->
342 case putMVar# mvar# x s# of
345 -- |A non-blocking version of 'takeMVar'. The 'tryTakeMVar' function
346 -- returns immediately, with 'Nothing' if the 'MVar' was empty, or
347 -- @'Just' a@ if the 'MVar' was full with contents @a@. After 'tryTakeMVar',
348 -- the 'MVar' is left empty.
349 tryTakeMVar :: MVar a -> IO (Maybe a)
350 tryTakeMVar (MVar m) = IO $ \ s ->
351 case tryTakeMVar# m s of
352 (# s, 0#, _ #) -> (# s, Nothing #) -- MVar is empty
353 (# s, _, a #) -> (# s, Just a #) -- MVar is full
355 -- |A non-blocking version of 'putMVar'. The 'tryPutMVar' function
356 -- attempts to put the value @a@ into the 'MVar', returning 'True' if
357 -- it was successful, or 'False' otherwise.
358 tryPutMVar :: MVar a -> a -> IO Bool
359 tryPutMVar (MVar mvar#) x = IO $ \ s# ->
360 case tryPutMVar# mvar# x s# of
361 (# s, 0# #) -> (# s, False #)
362 (# s, _ #) -> (# s, True #)
364 -- |Check whether a given 'MVar' is empty.
366 -- Notice that the boolean value returned is just a snapshot of
367 -- the state of the MVar. By the time you get to react on its result,
368 -- the MVar may have been filled (or emptied) - so be extremely
369 -- careful when using this operation. Use 'tryTakeMVar' instead if possible.
370 isEmptyMVar :: MVar a -> IO Bool
371 isEmptyMVar (MVar mv#) = IO $ \ s# ->
372 case isEmptyMVar# mv# s# of
373 (# s2#, flg #) -> (# s2#, not (flg ==# 0#) #)
375 -- |Add a finalizer to an 'MVar' (GHC only). See "Foreign.ForeignPtr" and
376 -- "System.Mem.Weak" for more about finalizers.
377 addMVarFinalizer :: MVar a -> IO () -> IO ()
378 addMVarFinalizer (MVar m) finalizer =
379 IO $ \s -> case mkWeak# m () finalizer s of { (# s1, w #) -> (# s1, () #) }
383 %************************************************************************
385 \subsection{Thread waiting}
387 %************************************************************************
390 #ifdef mingw32_HOST_OS
392 -- Note: threadDelay, threadWaitRead and threadWaitWrite aren't really functional
393 -- on Win32, but left in there because lib code (still) uses them (the manner
394 -- in which they're used doesn't cause problems on a Win32 platform though.)
396 asyncRead :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
397 asyncRead (I# fd) (I# isSock) (I# len) (Ptr buf) =
398 IO $ \s -> case asyncRead# fd isSock len buf s of
399 (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
401 asyncWrite :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
402 asyncWrite (I# fd) (I# isSock) (I# len) (Ptr buf) =
403 IO $ \s -> case asyncWrite# fd isSock len buf s of
404 (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
406 asyncDoProc :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
407 asyncDoProc (FunPtr proc) (Ptr param) =
408 -- the 'length' value is ignored; simplifies implementation of
409 -- the async*# primops to have them all return the same result.
410 IO $ \s -> case asyncDoProc# proc param s of
411 (# s, len#, err# #) -> (# s, I# err# #)
413 -- to aid the use of these primops by the IO Handle implementation,
414 -- provide the following convenience funs:
416 -- this better be a pinned byte array!
417 asyncReadBA :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int,Int)
418 asyncReadBA fd isSock len off bufB =
419 asyncRead fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
421 asyncWriteBA :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int,Int)
422 asyncWriteBA fd isSock len off bufB =
423 asyncWrite fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
427 -- -----------------------------------------------------------------------------
430 -- | Block the current thread until data is available to read on the
431 -- given file descriptor (GHC only).
432 threadWaitRead :: Fd -> IO ()
434 #ifndef mingw32_HOST_OS
435 | threaded = waitForReadEvent fd
437 | otherwise = IO $ \s ->
438 case fromIntegral fd of { I# fd# ->
439 case waitRead# fd# s of { s -> (# s, () #)
442 -- | Block the current thread until data can be written to the
443 -- given file descriptor (GHC only).
444 threadWaitWrite :: Fd -> IO ()
446 #ifndef mingw32_HOST_OS
447 | threaded = waitForWriteEvent fd
449 | otherwise = IO $ \s ->
450 case fromIntegral fd of { I# fd# ->
451 case waitWrite# fd# s of { s -> (# s, () #)
454 -- | Suspends the current thread for a given number of microseconds
457 -- Note that the resolution used by the Haskell runtime system's
458 -- internal timer is 1\/50 second, and 'threadDelay' will round its
459 -- argument up to the nearest multiple of this resolution.
461 -- There is no guarantee that the thread will be rescheduled promptly
462 -- when the delay has expired, but the thread will never continue to
463 -- run /earlier/ than specified.
465 threadDelay :: Int -> IO ()
467 #ifndef mingw32_HOST_OS
468 | threaded = waitForDelayEvent time
470 | threaded = c_Sleep (fromIntegral (time `quot` 1000))
472 | otherwise = IO $ \s ->
473 case fromIntegral time of { I# time# ->
474 case delay# time# s of { s -> (# s, () #)
477 -- On Windows, we just make a safe call to 'Sleep' to implement threadDelay.
478 #ifdef mingw32_HOST_OS
479 foreign import ccall safe "Sleep" c_Sleep :: CInt -> IO ()
482 foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
484 -- ----------------------------------------------------------------------------
485 -- Threaded RTS implementation of threadWaitRead, threadWaitWrite, threadDelay
487 -- In the threaded RTS, we employ a single IO Manager thread to wait
488 -- for all outstanding IO requests (threadWaitRead,threadWaitWrite)
489 -- and delays (threadDelay).
491 -- We can do this because in the threaded RTS the IO Manager can make
492 -- a non-blocking call to select(), so we don't have to do select() in
493 -- the scheduler as we have to in the non-threaded RTS. We get performance
494 -- benefits from doing it this way, because we only have to restart the select()
495 -- when a new request arrives, rather than doing one select() each time
496 -- around the scheduler loop. Furthermore, the scheduler can be simplified
497 -- by not having to check for completed IO requests.
499 -- Issues, possible problems:
501 -- - we might want bound threads to just do the blocking
502 -- operation rather than communicating with the IO manager
503 -- thread. This would prevent simgle-threaded programs which do
504 -- IO from requiring multiple OS threads. However, it would also
505 -- prevent bound threads waiting on IO from being killed or sent
508 -- - Apprently exec() doesn't work on Linux in a multithreaded program.
509 -- I couldn't repeat this.
511 -- - How do we handle signal delivery in the multithreaded RTS?
513 -- - forkProcess will kill the IO manager thread. Let's just
514 -- hope we don't need to do any blocking IO between fork & exec.
516 #ifndef mingw32_HOST_OS
519 = Read {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
520 | Write {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
523 = Delay {-# UNPACK #-} !Int {-# UNPACK #-} !(MVar ())
525 pendingEvents :: IORef [IOReq]
526 pendingDelays :: IORef [DelayReq]
527 -- could use a strict list or array here
528 {-# NOINLINE pendingEvents #-}
529 {-# NOINLINE pendingDelays #-}
530 (pendingEvents,pendingDelays) = unsafePerformIO $ do
535 -- the first time we schedule an IO request, the service thread
536 -- will be created (cool, huh?)
538 startIOServiceThread :: IO ()
539 startIOServiceThread = do
540 allocaArray 2 $ \fds -> do
541 throwErrnoIfMinus1 "startIOServiceThread" (c_pipe fds)
542 rd_end <- peekElemOff fds 0
543 wr_end <- peekElemOff fds 1
544 writeIORef stick (fromIntegral wr_end)
546 allocaBytes sizeofFdSet $ \readfds -> do
547 allocaBytes sizeofFdSet $ \writefds -> do
548 allocaBytes sizeofTimeVal $ \timeval -> do
549 service_loop (fromIntegral rd_end) readfds writefds timeval [] []
552 -- XXX: move real forkIO here from Control.Concurrent?
553 quickForkIO action = IO $ \s ->
554 case (fork# action s) of (# s1, id #) -> (# s1, ThreadId id #)
557 :: Fd -- listen to this for wakeup calls
564 service_loop wakeup readfds writefds ptimeval old_reqs old_delays = do
566 -- pick up new IO requests
567 new_reqs <- atomicModifyIORef pendingEvents (\a -> ([],a))
568 let reqs = new_reqs ++ old_reqs
570 -- pick up new delay requests
571 new_delays <- atomicModifyIORef pendingDelays (\a -> ([],a))
572 let delays = foldr insertDelay old_delays new_delays
574 -- build the FDSets for select()
578 maxfd <- buildFdSets 0 readfds writefds reqs
580 -- check the current time and wake up any thread in threadDelay whose
581 -- timeout has expired. Also find the timeout value for the select() call.
583 (delays', timeout) <- getDelay now ptimeval delays
585 -- perform the select()
587 res <- c_select ((max wakeup maxfd)+1) readfds writefds
598 -- ToDo: check result
600 b <- takeMVar prodding
601 if b then alloca $ \p -> do c_read (fromIntegral wakeup) p 1; return ()
603 putMVar prodding False
605 reqs' <- completeRequests reqs readfds writefds []
606 service_loop wakeup readfds writefds ptimeval reqs' delays'
609 {-# NOINLINE stick #-}
610 stick = unsafePerformIO (newIORef 0)
612 prodding :: MVar Bool
613 {-# NOINLINE prodding #-}
614 prodding = unsafePerformIO (newMVar False)
616 prodServiceThread :: IO ()
617 prodServiceThread = do
618 b <- takeMVar prodding
620 then do fd <- readIORef stick
621 with 42 $ \pbuf -> do c_write (fromIntegral fd) pbuf 1; return ()
623 putMVar prodding True
625 -- -----------------------------------------------------------------------------
628 buildFdSets maxfd readfds writefds [] = return maxfd
629 buildFdSets maxfd readfds writefds (Read fd m : reqs) = do
631 buildFdSets (max maxfd fd) readfds writefds reqs
632 buildFdSets maxfd readfds writefds (Write fd m : reqs) = do
634 buildFdSets (max maxfd fd) readfds writefds reqs
636 completeRequests [] _ _ reqs' = return reqs'
637 completeRequests (Read fd m : reqs) readfds writefds reqs' = do
638 b <- fdIsSet fd readfds
640 then do putMVar m (); completeRequests reqs readfds writefds reqs'
641 else completeRequests reqs readfds writefds (Read fd m : reqs')
642 completeRequests (Write fd m : reqs) readfds writefds reqs' = do
643 b <- fdIsSet fd writefds
645 then do putMVar m (); completeRequests reqs readfds writefds reqs'
646 else completeRequests reqs readfds writefds (Write fd m : reqs')
648 waitForReadEvent :: Fd -> IO ()
649 waitForReadEvent fd = do
651 atomicModifyIORef pendingEvents (\xs -> (Read fd m : xs, ()))
655 waitForWriteEvent :: Fd -> IO ()
656 waitForWriteEvent fd = do
658 atomicModifyIORef pendingEvents (\xs -> (Write fd m : xs, ()))
662 -- XXX: move into GHC.IOBase from Data.IORef?
663 atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
664 atomicModifyIORef (IORef (STRef r#)) f = IO $ \s -> atomicModifyMutVar# r# f s
666 -- -----------------------------------------------------------------------------
669 waitForDelayEvent :: Int -> IO ()
670 waitForDelayEvent usecs = do
673 let target = now + usecs `quot` tick_usecs
674 atomicModifyIORef pendingDelays (\xs -> (Delay target m : xs, ()))
678 -- Walk the queue of pending delays, waking up any that have passed
679 -- and return the smallest delay to wait for. The queue of pending
680 -- delays is kept ordered.
681 getDelay :: Ticks -> Ptr CTimeVal -> [DelayReq] -> IO ([DelayReq], Ptr CTimeVal)
682 getDelay now ptimeval [] = return ([],nullPtr)
683 getDelay now ptimeval all@(Delay time m : rest)
686 getDelay now ptimeval rest
688 setTimevalTicks ptimeval (time - now)
689 return (all,ptimeval)
691 insertDelay :: DelayReq -> [DelayReq] -> [DelayReq]
692 insertDelay d@(Delay time m) [] = [d]
693 insertDelay d1@(Delay time m) ds@(d2@(Delay time' m') : rest)
694 | time <= time' = d1 : ds
695 | otherwise = d2 : insertDelay d1 rest
698 tick_freq = 50 :: Ticks -- accuracy of threadDelay (ticks per sec)
699 tick_usecs = 1000000 `quot` tick_freq :: Int
701 newtype CTimeVal = CTimeVal ()
703 foreign import ccall unsafe "sizeofTimeVal"
706 foreign import ccall unsafe "getTicksOfDay"
707 getTicksOfDay :: IO Ticks
709 foreign import ccall unsafe "setTimevalTicks"
710 setTimevalTicks :: Ptr CTimeVal -> Ticks -> IO ()
712 -- ----------------------------------------------------------------------------
713 -- select() interface
715 -- ToDo: move to System.Posix.Internals?
717 newtype CFdSet = CFdSet ()
719 foreign import ccall safe "select"
720 c_select :: Fd -> Ptr CFdSet -> Ptr CFdSet -> Ptr CFdSet -> Ptr CTimeVal
723 foreign import ccall unsafe "hsFD_CLR"
724 fdClr :: Fd -> Ptr CFdSet -> IO ()
726 foreign import ccall unsafe "hsFD_ISSET"
727 fdIsSet :: Fd -> Ptr CFdSet -> IO CInt
729 foreign import ccall unsafe "hsFD_SET"
730 fdSet :: Fd -> Ptr CFdSet -> IO ()
732 foreign import ccall unsafe "hsFD_ZERO"
733 fdZero :: Ptr CFdSet -> IO ()
735 foreign import ccall unsafe "sizeof_fd_set"